Sublingual immune cell clusters and dendritic cell distribution in the oral cavity
Kusumoto et al. provide detailed analysis of dendritic cell (DC) distribution in the oral mucosa and report sublingual T cell–DC clusters and their immune composition. The cover image shows YFP+ DCs (single and clustered) in the posterior part of the sublingual region in a tissue-cleared tongue of a CD11c-YFP mouse. Tongue papillae are visible with red signals.
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Research Articles
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Abstract
Despite growing recognition, neuropsychiatric diseases associated with infections are a major unsolved problem worldwide. Group A streptococcal (GAS) infections can cause autoimmune sequelae characterized by movement disorders, such as Sydenham chorea, and neuropsychiatric disorders. The molecular mechanisms underlying these diseases are not fully understood. Our previous work demonstrates that autoantibodies (AAbs) can target dopaminergic neurons and increase dopamine D2 receptor (D2R) signaling. However, AAb influence on dopamine D1 receptor (D1R) activity is underexplored. We found evidence that suggests GAS-induced cross-reactive AAbs promote autoimmune encephalitis of the basal ganglia, a region of high dopamine receptor density. Here, we report a mechanism whereby neuropsychiatric syndromes are distinguished from movement disorders by differences in D1R and D2R AAb titers, signaling, receiver operating characteristic curves, and immunoreactivity with D1R and D2R autoreactive epitopes. D1R AAb signaling was observed through patient serum AAbs and novel patient-derived monoclonal antibodies (mAbs), which induced both D1R G protein– and β-arrestin–transduced signals. Furthermore, patient AAbs and mAbs enhanced D1R signaling mechanisms mediated by the neurotransmitter dopamine. Our findings suggest that AAb-mediated D1R signaling may contribute to the pathogenesis of neuropsychiatric sequelae and inform new options for diagnosis and treatment of GAS sequelae and related disorders.
Authors
Chandra M. Menendez, Jonathan Zuccolo, Susan E. Swedo, Sean Reim, Brian Richmand, Hilla Ben-Pazi, Abraham Kovoor, Madeleine W. Cunningham
×Abstract
The oral mucosa is the first line of defense against pathogenic bacteria and plays a vital role in maintaining tolerance to food antigens and commensal bacteria. We used CD11c reporter mice to visualize dendritic cells (DCs), a key immune cell population, in the oral cavity. We identified differences in DC density in each oral tissue region. Sublingual immune cell clusters (SLICs) extended from the lamina propria to the epithelium, where DCs and T cells resided in close contact with each other and innate lymphoid cells. Targeted in situ photolabeling revealed that the SLICs comprised mostly CD11c+CD11b+ DCs and were enriched for cDC1s and Langerhans cells. Although the frequency of T cell subsets was similar within and outside the SLICs, tissue-resident memory T cells were significantly enriched within the clusters and cluster size increased in response to inflammation. Collectively, we found that SLICs form a unique microenvironment that facilitates T cell–DC interactions in the steady state and during inflammation. Since the oral mucosa is an important target for needle-free vaccination and sublingual immunotherapy to induce tolerogenic responses, the insight into the localized immunoregulation provided in this study may accelerate the development of these approaches.
Authors
Yutaka Kusumoto, Mizuki Ueda, Mayuko Hashimoto, Haruka Takeuchi, Naoko Okada, Junya Yamamoto, Akiko Nishii, Atsuki Fujino, Akiho Kurahashi, Momoka Satoh, Yuki Iwasa, Koki Okamura, Karin Obazaki, Ryoto Kumagai, Naruya Sakamoto, Yuto Tanaka, Yukika Kamiya, Tetsushi Hoshida, Tsuneyasu Kaisho, Hiroaki Hemmi, Tomoya Katakai, Tetsuya Honda, Junichi Kikuta, Kosuke Kataoka, Ryoyo Ikebuchi, Taiki Moriya, Takahiro Adachi, Takeshi Watanabe, Masaru Ishii, Atsushi Miyawaki, Kenji Kabashima, Tatyana Chtanova, Michio Tomura
×Abstract
BACKGROUND Inhibition of Bruton’s tyrosine kinase with ibrutinib blocks the function of myeloid-derived suppressor cells (MDSC). The combination of ibrutinib and nivolumab was tested in patients with metastatic solid tumors.METHODS Sixteen patients received ibrutinib 420 mg p.o. daily with nivolumab 240 mg i.v. on days 1 and 15 of a 28-day cycle. The effect of ibrutinib and nivolumab on MDSC, the immune profile, and cytokine levels were measured. Single-cell RNA-Seq and T cell receptor sequencing of immune cells was performed.RESULTS Common adverse events were fatigue and anorexia. Four patients had partial responses and 4 had stable disease at 3 months (average 6.5 months, range 3.5–14.6). Median overall survival (OS) was 10.8 months. Seven days of Bruton’s tyrosine kinase (BTK) inhibition significantly increased the proportion of monocytic-MDSC (M-MDSC) and significantly decreased chemokines associated with MDSC recruitment and accumulation (CCL2, CCL3, CCL4, CCL13). Single-cell RNA-Seq revealed ibrutinib-induced downregulation of genes associated with MDSC-suppressive function (TIMP1, CXCL8, VEGFA, HIF1A), reduced MDSC interactions with exhausted CD8+ T cells, and decreased TCR repertoire diversity. The addition of nivolumab significantly increased circulating NK and CD8+ T cells and increased CD8+ T cell proliferation. Exploratory analyses suggest that MDSC and T cell gene expression and TCR repertoire diversity were differentially affected by BTK inhibition according to patient response.CONCLUSION Ibrutinib and nivolumab were well tolerated and affected MDSC and T cell function in patients with solid metastatic tumors.TRIAL REGISTRATION ClinicalTrials.gov NCT03525925.FUNDING NIH; National Cancer Institute Cancer; National Center for Advancing Translational Sciences; Pelotonia.
Authors
Emily Schwarz, Brooke Benner, Robert Wesolowski, Dionisia Quiroga, Logan Good, Steven H. Sun, Himanshu Savardekar, Jianying Li, Kyeong Joo Jung, Megan C. Duggan, Gabriella Lapurga, Jami Shaffer, Luke Scarberry, Bhavana Konda, Claire Verschraegen, Kari Kendra, Manisha Shah, Robert Rupert, Paul Monk, Hiral A. Shah, Anne M. Noonan, Kristin Bixel, John Hays, Lai Wei, Xueliang Pan, Gregory Behbehani, Yang Hu, Olivier Elemento, Dongjun Chung, Gang Xin, Bradley W. Blaser, William E. Carson III
×Abstract
Psoriasis is a chronic and recurrent inflammatory skin disease characterized by abnormal proliferation and differentiation of keratinocytes and activation of immune cells. However, the molecular driver that triggers this immune response in psoriatic skin remains unclear. The inflammation-related gene absent in melanoma 2 (AIM2) was identified as a susceptibility gene/locus associated with psoriasis. In this study, we investigated the role of AIM2 in the pathophysiology of psoriasis. We found elevated levels of mitochondrial DNA in patients with psoriasis, along with high expression of AIM2 in both the human psoriatic epidermis and a mouse model of psoriasis induced by topical imiquimod (IMQ) application. Genetic ablation of AIM2 reduced the development of IMQ-induced psoriasis by decreasing the production of type 3 cytokines (such as IL-17A and IL-23) and infiltration of immune cells into the inflammatory site. Furthermore, we demonstrate that IL-17A induced AIM2 expression in keratinocytes. Finally, the genetic absence of inflammasome components downstream AIM2, ASC, and caspase-1 alleviated IMQ-induced skin inflammation. Collectively, our data show that AIM2 is involved in developing psoriasis through its canonical activation.
Authors
Timna Varela Martins, Bruno Marcel Silva de Melo, Juliana Escher Toller-Kawahisa, Gabriel Victor Lucena da Silva, Conceição Elidianne Aníbal Silva, Isadora Marques Paiva, Gabriel Azevedo Públio, Marcos Henrique Rosa, Cacilda da Silva Souza, Dario Simões Zamboni, Fernando Q. Cunha, Thiago Mattar Cunha, Bernhard Ryffel, Nicolas Riteau, José C. Alves-Filho
×Abstract
Effective, reproducible, and safe delivery of therapeutics into the inner ear is required for the prevention and treatment of hearing loss. A commonly used delivery method is via the posterior semicircular canal (PSCC); however, its specific targeting within the cochlea remains unclear, impacting precision and reproducibility. To assess safety and target specificity, we conducted in vivo recordings of the pharmacological manipulations delivered through the PSCC. Measurements of auditory brainstem response (ABR), vibrometry, and vestibular behavioral and sensory-evoked potential (VsEP) revealed preserved hearing and vestibular functions after artificial perilymph injections. Injection of curare, a mechanoelectrical transducer (MET) channel blocker that affects hearing when in the endolymph, had no effect on ABR or VsEP thresholds. Conversely, injection of CNQX, an AMPA receptor blocker, or lidocaine, a Na+ channel blocker, which affects hearing when in the perilymph, significantly increased both thresholds, indicating that PSCC injections selectively target the perilymphatic space. In vivo tracking of gold nanoparticles confirmed their exclusive distribution in the perilymph during PSCC injection, supporting the pharmacological finding. Together, PSCC injection is a safe method for inner ear delivery, specifically targeting the perilymphatic space. Our findings will allow for precise delivery of therapeutics within the inner ear for therapeutic and research purposes.
Authors
Jinkyung Kim, Jesus Maldonado, Dorothy W. Pan, Patricia M. Quiñones, Samantha Zenteno, John S. Oghalai, Anthony J. Ricci
×Abstract
Recent studies have identified multiple genetic variants of SEL1L-HRD1 endoplasmic reticulum–associated degradation (ERAD) in humans with neurodevelopmental disorders and locomotor dysfunctions, including ataxia. However, the relevance and importance of SEL1L-HRD1 ERAD in the pathogenesis of ataxia remain unexplored. Here, we showed that SEL1L deficiency in Purkinje cells leads to early-onset progressive cerebellar ataxia with progressive loss of Purkinje cells with age. Mice with Purkinje cell–specific deletion of SEL1L (Sel1LPcp2Cre) exhibited motor dysfunction beginning around 9 weeks of age. Transmission electron microscopy analysis revealed dilated ER and fragmented nuclei in Purkinje cells of adult Sel1LPcp2Cre mice, indicative of altered ER homeostasis and cell death. Finally, loss of Purkinje cells was associated with a secondary neurodegeneration of granular cells, as well as robust activation of astrocytes and proliferation of microglia, in the cerebellums of Sel1LPcp2Cre mice. These data demonstrate the pathophysiological importance of SEL1L-HRD1 ERAD in Purkinje cells in the pathogenesis of cerebellar ataxia.
Authors
Mauricio Torres, Brent Pederson, Hui Wang, Liangguang Leo Lin, Huilun Helen Wang, Amara Bugarin-Lapuz, Zhen Zhao, Ling Qi
×Abstract
As the aging process progresses, age-related intervertebral disc degeneration (IVDD) is becoming an emerging public health issue. Site-1 protease (S1P) has recently been found to be associated with abnormal spinal development in patients with mutations and has multiple biological functions. Here, we discovered a reduction of S1P in degenerated and aging intervertebral discs, primarily regulated by DNA methylation. Furthermore, through drug treatment and siRNA-mediated S1P knockdown, nucleus pulposus cells were more prone to exhibit degenerative and aging phenotypes. Conditional KO of S1P in mice resulted in spinal developmental abnormalities and premature aging. Mechanistically, S1P deficiency impeded COP II–mediated transport vesicle formation, which leads to protein retention in the endoplasmic reticulum (ER) and subsequently ER distension. ER distension increased the contact between the ER and mitochondria, disrupting ER-to-mitochondria calcium flow and resulting in mitochondrial dysfunction and energy metabolism disturbance. Finally, using 2-APB to inhibit calcium ion channels and the senolytic drug dasatinib and quercetin (D + Q) partially rescued the aging and degenerative phenotypes caused by S1P deficiency. In conclusion, our findings suggest that S1P is a critical factor in causing IVDD in the process of aging and highlight the potential of targeting S1P as a therapeutic approach for age-related IVDD.
Authors
Bingjie Zheng, Xuyang Zhang, Xiangxi Kong, Jie Li, Bao Huang, Hui Li, Zhongyin Ji, Xiaoan Wei, Siyue Tao, Zhi Shan, Zemin Ling, Junhui Liu, Jian Chen, Fengdong Zhao
×Abstract
Tumor cell–derived prostaglandin E2 (PGE2) is a tumor cell–intrinsic factor that supports immunosuppression in the tumor microenvironment (TME) by acting on the immune cells, but the impact of PGE2 signaling in tumor cells on the immunosuppressive TME is unclear. We demonstrate that deleting the PGE2 synthesis enzyme or disrupting autocrine PGE2 signaling through EP4 receptors on tumor cells reverses the T cell–low, myeloid cell–rich TME, activates T cells, and suppresses tumor growth. Knockout (KO) of Ptges (the gene encoding the PGE2 synthesis enzyme mPGES-1) or the EP4 receptor gene (Ptger4) in KPCY (KrasG12D P53R172H Yfp CrePdx) pancreatic tumor cells abolished growth of implanted tumors in a T cell–dependent manner. Blockade of the EP4 receptor in combination with immunotherapy, but not immunotherapy alone, induced complete tumor regressions and immunological memory. Mechanistically, Ptges- and Ptger4-KO tumor cells exhibited altered T and myeloid cell attractant chemokines, became more susceptible to TNF-α–induced killing, and exhibited reduced adenosine synthesis. In hosts treated with an adenosine deaminase inhibitor, Ptger4-KO tumor cells accumulated adenosine and gave rise to tumors. These studies reveal an unexpected finding — a nonredundant role for the autocrine mPGES-1/PGE2/EP4 signaling axis in pancreatic cancer cells, further nominating mPGES-1 inhibition and EP4 blockade as immune-sensitizing therapy in cancer.
Authors
Nune Markosyan, Il-Kyu Kim, Charu Arora, Liz Quinones-Ware, Nikhil Joshi, Noah Cheng, Emma Y. Schechter, John W. Tobias, Joseph E. Hochberg, Emily Corse, Kang Liu, Varenka Rodriguez DiBlasi, Li-Chuan (Eric) Chan, Emer M. Smyth, Garret A. FitzGerald, Ben Z. Stanger, Robert H. Vonderheide
×Abstract
Gaucher disease, the most prevalent lysosomal storage disease, is caused by homozygous mutations at the GBA gene, which is responsible for encoding the enzyme glucocerebrosidase. Neuronopathic Gaucher disease is associated with microgliosis, astrogliosis, and neurodegeneration. However, the role that microglia, astrocytes, and neurons play in the disease remains to be determined. In the current study, we developed inducible, cell-type-specific Gba-KO mice to better understand the individual impacts of Gba deficiencies on microglia and neurons. Gba was conditionally knocked out either exclusively in microglia or neurons or throughout the body. These mouse models were developed using a tamoxifen-inducible Cre system, with tamoxifen administration commencing at weaning. Microglia-specific Gba-KO mice showed no signs of disease. However, the neuron-specific Gba KO resulted in a shortened lifespan, severe weight loss, and ataxia. These mice also had significant neurodegeneration, microgliosis, and astrogliosis accompanied by the accumulation of glucosylceramide and glucosylsphingosine, recapitulating Gaucher disease–like symptoms. These surprising findings reveal that, unlike the neuron-specific Gba deficiency, microglia-specific Gba deficiency alone does not induce disease. The neuronal Gaucher disease mouse model, with a median survival of 16 weeks, may be useful for future studies of pathogenesis and the evaluation of therapies.
Authors
Hannah B.D. Duffy, Colleen Byrnes, Hongling Zhu, Galina Tuymetova, Y. Terry Lee, Frances M. Platt, Richard L. Proia
×Abstract
Radiotherapy (RT) remains a primary treatment modality for glioblastoma (GBM), but it induces cellular senescence and is strongly implicated in GBM progression and RT-related injury. Recently, eliminating senescent cells has emerged as a promising strategy for treating cancer and for mitigating radiation-induced brain injury (RBI). Here, we investigated the impact of all-trans retinoic acid (RA) on radiation-induced senescence. The findings of this study revealed that RA effectively eliminated astrocytes, which are particularly prone to senescence after radiation, and that the removal of senescence-associated secretory phenotype factor–producing astrocytes inhibited GBM cell proliferation in vitro. Moreover, RA-mediated clearance of senescent cells improved survival in GBM-bearing mice and alleviated radiation-induced cognitive impairment. Through RNA sequencing, we found that the AKT/mTOR/PPARγ/Plin4 signaling pathway is involved in RA-mediated clearance of senescent cells. In summary, these results suggest that RA could be a potential senolytic drug for preventing GBM progression and improving RBI.
Authors
Min Fu, Yiling Zhang, Bi Peng, Na Luo, Yuanyuan Zhang, Wenjun Zhu, Feng Yang, Ziqi Chen, Qiang Zhang, Qianxia Li, Xin Chen, Yuanhui Liu, Guoxian Long, Guangyuan Hu, Xiaohong Peng
×Abstract
Mucosal melanoma (MucM) is a rare cancer with a poor prognosis and low response rate to immune checkpoint inhibition (ICI) compared with cutaneous melanoma (CM). To explore the immune microenvironment and potential drivers of MucM’s relative resistance to ICI drugs, we characterized 101 MucM tumors (43 head and neck [H&N], 31 female urogenital, 13 male urogenital, 11 anorectal, and 3 other gastrointestinal) using bulk RNA-Seq and immunofluorescence. RNA-Seq data show that MucM has a significantly lower IFN-γ signature levels than CM. MucM tumors of the H&N region show a significantly greater abundance of CD8+ T cells, cytotoxic cells, and higher IFN-γ signature levels than MucM from lower body sites. In the subcohort of 35 patients with MucM treated with ICI, hierarchical clustering reveals clusters with a high and low degree of immune infiltration, with a differential ICI response rate. Immune-associated gene sets were enriched in responders. Signatures associated with cancer-associated fibroblasts, macrophages, and TGF-β signaling may be higher in immune-infiltrated, but ICI-unresponsive tumors, suggesting a role for these resistance mechanisms in MucM. Our data show organ region–specific differences in immune infiltration and IFN-γ signature levels in MucM, with H&N MucM displaying the most favorable immune profile. Our study might offer a starting point for developing more personalized treatment strategies for this disease.
Authors
Joris L. Vos, Joleen J.H. Traets, Xiaohang Qiao, Iris M. Seignette, Dennis Peters, Michel W.J.M. Wouters, Erik Hooijberg, Annegien Broeks, Jacqueline E. van der Wal, M. Baris Karakullukcu, W. Martin C. Klop, Arash Navran, Marc van Beurden, Oscar R. Brouwer, Luc G.T. Morris, Mariette I.E. van Poelgeest, Ellen Kapiteijn, John B.A.G. Haanen, Christian U. Blank, Charlotte L. Zuur
×Abstract
The blood-brain barrier (BBB) is critical for maintaining brain homeostasis but is susceptible to inflammatory dysfunction. While transporter-dependent efflux of some lipophilic substrates across the BBB shows circadian variation due to rhythmic transporter expression, basal transporter–independent permeability and leakage is nonrhythmic. Whether daily timing influences BBB permeability in response to inflammation is unknown. Here, we induced systemic inflammation through repeated LPS injections either in the morning (ZT1) or evening (ZT13) under standard lighting conditions; we then examined BBB permeability to a polar molecule that is not a transporter substrate, sodium fluorescein. We observed clear diurnal variation in inflammatory BBB permeability, with a striking increase in paracellular leak across the BBB specifically following evening LPS injection. Evening LPS led to persisting glia activation as well as inflammation in the brain that was not observed in the periphery. The exaggerated evening neuroinflammation and BBB disruption were suppressed by microglial depletion or through keeping mice in constant darkness. Our data show that diurnal rhythms in microglial inflammatory responses to LPS drive daily variability in BBB breakdown and reveal time of day as a key regulator of inflammatory BBB disruption.
Authors
Jennifer H. Lawrence, Asha Patel, Melvin W. King, Collin J. Nadarajah, Richard Daneman, Erik S. Musiek
×Abstract
Transcriptomic analyses have advanced the understanding of complex disease pathophysiology including chronic obstructive pulmonary disease (COPD). However, identifying relevant biologic causative factors has been limited by the integration of high dimensionality data. COPD is characterized by lung destruction and inflammation, with smoke exposure being a major risk factor. To define previously unknown biological mechanisms in COPD, we utilized unsupervised and supervised interpretable machine learning analyses of single-cell RNA-Seq data from the mouse smoke-exposure model to identify significant latent factors (context-specific coexpression modules) impacting pathophysiology. The machine learning transcriptomic signatures coupled to protein networks uncovered a reduction in network complexity and new biological alterations in actin-associated gelsolin (GSN), which was transcriptionally linked to disease state. GSN was altered in airway epithelial cells in the mouse model and in human COPD. GSN was increased in plasma from patients with COPD, and smoke exposure resulted in enhanced GSN release from airway cells from patients with COPD. This method provides insights into rewiring of transcriptional networks that are associated with COPD pathogenesis and provides a translational analytical platform for other diseases.
Authors
Justin Sui, Hanxi Xiao, Ugonna Mbaekwe, Nai-Chun Ting, Kaley Murday, Qianjiang Hu, Alyssa D. Gregory, Theodore S. Kapellos, Ali Öender Yildirim, Melanie Königshoff, Yingze Zhang, Frank Sciurba, Jishnu Das, Corrine R. Kliment
×Abstract
Pneumonia is a worldwide threat to public health, demanding novel preventative and therapeutic strategies. The lung epithelium is a critical environmental interface that functions as a physical barrier to pathogen invasion while also actively sensing and responding to pathogens. We have reported that stimulating lung epithelial cells with a combination therapeutic consisting of a diacylated lipopeptide and a synthetic CpG oligodeoxynucleotide (ODN) induces synergistic pneumonia protection against a wide range of pathogens. We report here that mice deficient in TLR9, the previously described receptor for ODN, still displayed partial ODN-induced protection. This prompted us to seek an alternate ODN receptor, and we discovered by mass spectroscopy that the RNA sensor RIG-I could also bind DNA-like ODN. ODN binding by RIG-I resulted in MAVS-dependent pneumonia-protective signaling events. While RIG-I is essential to native defenses against viral infections, we report that therapeutic RIG-I activation with ODN promoted pathogen killing and host survival following both viral and bacterial challenges. These data indicate that maximal ODN-induced pneumonia protection requires activation of both the TLR9/MyD88 and RIG-I/MAVS signaling pathways. These findings not only identify what we believe to be a novel pattern recognition receptor for DNA-like molecules, but reveal a potential therapeutic strategy to protect susceptible individuals against lethal pneumonias during periods of peak vulnerability.
Authors
Yongxing Wang, Vikram V. Kulkarni, Jezreel PantaleónGarcía, Michael K. Longmire, Mathilde Lethier, Stephen Cusack, Scott E. Evans
×Abstract
In patients who progress from acute hepatitis B virus (HBV) infection to a chronic HBV (CHB) infection, CD8+ T cells fail to eliminate the virus and become impaired. A functional cure of CHB likely requires CD8+ T cell responses different from those induced by the infection. Here we report preclinical immunogenicity and efficacy of an HBV therapeutic vaccine that includes herpes simplex virus (HSV) glycoprotein D (gD), a checkpoint modifier of early T cell activation, that augments CD8+ T cell responses. The vaccine is based on a chimpanzee adenovirus serotype 6 (AdC6) vector, called AdC6-gDHBV2, which targets conserved and highly immunogenic regions of the viral polymerase and core antigens fused to HSV gD. The vaccine was tested with and without gD in mice for immunogenicity, and in an AAV8-1.3HBV vector model of antiviral efficacy. The vaccine encoding the HBV antigens within gD stimulates potent and broad CD8+ T cell responses. In a surrogate model of HBV infection, a single intramuscular injection achieved pronounced and sustained declines of circulating HBV DNA copies and HBV surface antigen; both inversely correlated with HBV-specific CD8+ T cell frequencies in spleen and liver.
Authors
Mohadeseh Hasanpourghadi, Mikhail Novikov, Robert Ambrose, Arezki Chekaoui, Dakota Newman, ZhiQuan Xiang, Andrew D. Luber, Sue L. Currie, XiangYang Zhou, Hildegund C.J. Ertl
×Abstract
Macrophages contribute to the induction and resolution of inflammation and play a central role in chronic low-grade inflammation in cardiovascular diseases caused by atherosclerosis. Human milk oligosaccharides (HMOs) are complex unconjugated glycans unique to human milk that benefit infant health and act as innate immune modulators. Here, we identify the HMO 3′sialyllactose (3′SL) as a natural inhibitor of TLR4-induced low-grade inflammation in macrophages and endothelium. Transcriptome analysis in macrophages revealed that 3′SL attenuates mRNA levels of a selected set of inflammatory genes and promotes the activity of liver X receptor (LXR) and sterol regulatory element binding protein-1 (SREBP1). These acute antiinflammatory effects of 3′SL were associated with reduced histone H3K27 acetylation at a subset of LPS-inducible enhancers distinguished by preferential enrichment for CCCTC-binding factor (CTCF), IFN regulatory factor 2 (IRF2), B cell lymphoma 6 (BCL6), and other transcription factor recognition motifs. In a murine atherosclerosis model, both s.c. and oral administration of 3′SL significantly reduced atherosclerosis development and the associated inflammation. This study provides evidence that 3′SL attenuates inflammation by a transcriptional mechanism to reduce atherosclerosis development in the context of cardiovascular disease.
Authors
Ariane R. Pessentheiner, Nathanael J. Spann, Chloe A. Autran, Tae Gyu Oh, Kaare V. Grunddal, Joanna K.C. Coker, Chelsea D. Painter, Bastian Ramms, Austin W.T. Chiang, Chen-Yi Wang, Jason Hsiao, Yiwen Wang, Anthony Quach, Laela M. Booshehri, Alexandra Hammond, Chiara Tognaccini, Joanna Latasiewicz, Lisa Willemsen, Karsten Zengler, Menno P.J. de Winther, Hal M. Hoffman, Martin Philpott, Adam P. Cribbs, Udo Oppermann, Nathan E. Lewis, Joseph L. Witztum, Ruth Yu, Annette R. Atkins, Michael Downes, Ron M. Evans, Christopher K. Glass, Lars Bode, Philip L.S.M. Gordts
×Abstract
Radiation-induced lung injury (RILI) initiates radiation pneumonitis and progresses to fibrosis as the main side effect experienced by patients with lung cancer treated with radiotherapy. There is no effective drug for RILI. Sustained vascular activation is a major contributor to the establishment of chronic disease. Here, using a whole thoracic irradiation (WTI) mouse model, we investigated the mechanisms and effectiveness of thrombopoietin mimetic (TPOm) for preventing RILI. We demonstrated that administering TPOm 24 hours before irradiation decreased histologic lung injury score, apoptosis, vascular permeability, expression of proinflammatory cytokines, and neutrophil infiltration in the lungs of mice 2 weeks after WTI. We described the expression of c-MPL, a TPO receptor, in mouse primary pulmonary microvascular endothelial cells, showing that TPOm reduced endothelial cell–neutrophil adhesion by inhibiting ICAM-1 expression. Seven months after WTI, TPOm-treated lung exhibited less collagen deposition and expression of MMP-9, TIMP-1, IL-6, TGF-β, and p21. Moreover, TPOm improved lung vascular structure, lung density, and respiration rate, leading to a prolonged survival time after WTI. Single-cell RNA sequencing analysis of lungs 2 weeks after WTI revealed that TPOm shifted populations of capillary endothelial cells toward a less activated and more homeostatic phenotype. Taken together, TPOm is protective for RILI by inhibiting endothelial cell activation.
Authors
Jeb English, Sriya Dhanikonda, Kathryn E. Tanaka, Wade Koba, Gary Eichenbaum, Weng-Lang Yang, Chandan Guha
×Abstract
Crosstalk between the microbiome and gut mucosa–resident immune cells plays a pivotal role in modulating immune responses to pathogens, including responses to HIV infection. However, how these interactions may differ between young men who have sex with men (YMSM) disproportionately impacted by HIV, as compared with older adult MSM (AMSM), is not well understood. A broad analysis of associations between the microbiome and rectal transcriptome revealed 10 microbial families/genera correlated with immunologic gene pathways. Specifically, the rectal transcriptome of YMSM was characterized by upregulation of T cell activation/differentiation pathways and signaling from multiple cytokine families compared with AMSM. The microbiome of YMSM was enriched with pathogenic genera, including Peptostreptococcus, shown to be positively correlated with type I IFN pathways important for antiviral immunity. These findings demonstrate that YMSM have a unique immune phenotype and rectal microenvironment and support further evaluation of biological factors that influence rectal HIV transmission.
Authors
Cassie G. Ackerley, S. Abigail Smith, Phillip M. Murray, Praveen K. Amancha, Vanessa E. Van Doren, Gregory K. Tharp, Robert A. Arthur, Rama R. Amara, Yi-Juan Hu, Colleen F. Kelley
×Abstract
Extracellular vesicles (EVs) have emerged as important mediators of intertissue signaling and exercise adaptations. In this human study, we provide evidence that muscle-specific microRNA-1 (miR-1) was transferred to adipose tissue via EVs following an acute bout of resistance exercise. Using a multimodel machine learning automation tool, we discovered muscle primary miR-1 transcript and CD63+ EV count in circulation as top explanatory features for changes in adipose miR-1 levels in response to resistance exercise. RNA-Seq and in-silico prediction of miR-1 target genes identified caveolin 2 (CAV2) and tripartite motif containing 6 (TRIM6) as miR-1 target genes downregulated in the adipose tissue of a subset of participants with the highest increases in miR-1 levels following resistance exercise. Overexpression of miR-1 in differentiated human adipocyte-derived stem cells downregulated these miR-1 targets and enhanced catecholamine-induced lipolysis. These data identify a potential EV-mediated mechanism by which skeletal muscle communicates with adipose tissue and modulates lipolysis via miR-1.
Authors
Benjamin I. Burke, Ahmed Ismaeel, Douglas E. Long, Lauren A. Depa, Peyton T. Coburn, Jensen Goh, Tolulope P. Saliu, Bonnie J. Walton, Ivan J. Vechetti, Bailey D. Peck, Taylor R. Valentino, C. Brooks Mobley, Hasiyet Memetimin, Dandan Wang, Brian S. Finlin, Philip A. Kern, Charlotte A. Peterson, John J. McCarthy, Yuan Wen
×Abstract
Despite their beneficial actions as immunosuppressants, glucocorticoids (GC) have devastating effects on the musculoskeletal and cardiac systems, as long-term treated patients exhibit high incidence of falls, bone fractures, and cardiovascular events. Herein, we show that GC upregulate simultaneously in bone, skeletal muscle, and the heart the expression of E3 ubiquitin ligases (atrogenes), known to stimulate the proteasomal degradation of proteins. Activation of vitamin D receptor (VDR) signaling with the VDR ligands calcitriol or eldecalcitol prevented GC-induced atrogene upregulation in vivo and ex vivo in bone/muscle organ cultures and preserved tissue structure/mass and function of the 3 tissues in vivo. Direct pharmacologic inhibition of the proteasome with carfilzomib also conferred musculoskeletal protection. Genetic loss of the atrogene MuRF1-mediated protein ubiquitination in ΔRING mice afforded temporary or sustained protection from GC excess in bone or skeletal and heart muscle. We concluded that the atrogene pathway downstream of MuRF1 underlies GC action in bone, muscle, and the heart, and it can be pharmacologically or genetically targeted to confer protection against the damaging actions of GC simultaneously in the 3 tissues.
Authors
Amy Y. Sato, Meloney Cregor, Kevin McAndrews, Charles A. Schurman, Eric Schaible, Jennifer Shutter, Punit Vyas, Bhawana Adhikari, Monte S. Willis, Marjan Boerma, Tamara Alliston, Teresita Bellido
×Abstract
The dual tumor-suppressive and -promoting functions of TGF-β signaling has made its targeting challenging. We examined the effects of TGF-β depletion by AVID200/BMS-986416 (TGF-β-TRAP), a TGF-β ligand trap, on the tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) murine models with different organ-specific metastasis. Our study demonstrated that TGF-β-TRAP potentiates the efficacy of anti–programmed cell death 1 (anti–PD-1) in a PDAC orthotopic murine model with liver metastasis tropism, significantly reducing liver metastases. We further demonstrated the heterogeneous response of cytotoxic effector T cells to combination TGF-β-TRAP and anti–PD-1 treatment across several tumor models. Single-nuclear RNA sequencing suggested that TGF-β-TRAP modulates cancer-associated fibroblast (CAF) heterogeneity and suppresses neutrophil degranulation and CD4+ T cell response to neutrophil degranulation. Ligand-receptor analysis indicated that TGF-β-TRAP may modulate the CCL5/CCR5 axis as well as costimulatory and checkpoint signaling from CAFs and myeloid cells. Notably, the most highly expressed ligands of CCR5 shifted from the immunosuppressive CCL5 to CCL7 and CCL8, which may mediate the immune agonist activity of CCR5 following TGF-β-TRAP and anti–PD-1 combination treatment. This study suggested that TGF-β depletion modulates CAF heterogeneity and potentially reprograms CAFs and myeloid cells into antitumor immune agonists in PDAC, supporting the validation of such effects in human specimens.
Authors
Sophia Y. Chen, Heng-Chung Kung, Birginia Espinoza, India Washington, Kai Chen, Jianxin Wang, Haley Zlomke, Michael Loycano, Rulin Wang, Michael Pickup, William R. Burns III, Juan Fu, William L. Hwang, Lei Zheng
×Abstract
BACKGROUND The toxic accumulation of phenylalanine (Phe) in the brain underlies the neurological presentation of phenylketonuria (PKU). Solute carrier family 6 member 19 (SLC6A19) is the major transporter responsible for the (re)absorption of Phe in the kidney and intestine. Here, we describe the characterization of the first small molecule SLC6A19 inhibitor to enter clinical development for the treatment of PKU.METHODS C57Bl/6J WT and Pahenu2 mice were dosed with an inhibitor of SLC6A19 to investigate the effects on urinary amino acids and plasma Phe. In a phase 1 study, healthy human volunteers were dosed with JNT-517, an investigational oral inhibitor of SLC6A19. The primary objective of the study was safety. Secondary objectives included pharmacokinetic and pharmacodynamic studies.RESULTS Inhibition of SLC6A19 increased the urinary excretion of Phe in a mouse model of PKU, thereby reducing plasma Phe levels. JNT-517, an investigational oral SLC6A19 inhibitor, was found to be safe and well tolerated and increased the urinary excretion of Phe in a phase 1 healthy volunteer study.CONCLUSIONS These data indicate that pharmacological inhibition of SLC6A19 presents a promising approach to lower toxic elevated levels of amino acids found in PKU and related amino acid metabolism disorders by facilitating their renal elimination.TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12622001222730.FUNDING The studies in this paper were funded by Jnana Therapeutics.
Authors
Heike J. Wobst, Andreu Viader, Giovanni Muncipinto, Ryan Hollibaugh, Daniel van Kalken, Christopher T. Burkhart, Susan M. Cantin, Rachel M. Bates, Yannik Regimbald-Dumas, Liam Gross, Mitchell T. Antalek, Joshua E. Zweig, Frank Wu, T. Justin Rettenmaier, Matthew T. Labenski, Nicholas Pullen, Heather S. Blanchette, Jaclyn L. Henderson, Haoling H. Weng, Toby A. Vaughn, Dean G. Brown, John P. Throup, Joel C. Barrish
×Abstract
Grover disease is an acquired epidermal blistering disorder in which keratinocytes lose intercellular connections. While its pathologic features are well defined, its etiology remains unclear, and there is no FDA-approved therapy. Interestingly, Grover disease was a common adverse event in clinical trials for cancer using B-RAF inhibitors, but it remained unknown how B-RAF blockade compromised skin integrity. Here, we identified ERK hyperactivation as a key driver of Grover disease pathology. We leveraged a fluorescent biosensor to confirm that the B-RAF inhibitors dabrafenib and vemurafenib paradoxically activated ERK in human keratinocytes and organotypic epidermis, disrupting cell-cell junctions and weakening epithelial integrity. Consistent with clinical data showing that concomitant MEK blockade prevents Grover disease in patients receiving B-RAF inhibitors, we found that MEK inhibition suppressed ERK and rescued cohesion of B-RAF–inhibited keratinocytes. Validating these results, we demonstrated ERK hyperactivation in patient biopsies from vemurafenib-induced Grover disease and from spontaneous Grover disease, revealing a common etiology for both. Finally, in line with our recent identification of ERK hyperactivation in Darier disease, a genetic disorder with identical pathology to Grover disease, our studies uncovered that the pathogenic mechanisms of these diseases converge on ERK signaling and support MEK inhibition as a therapeutic strategy.
Authors
Cory L. Simpson, Afua Tiwaa, Shivam A. Zaver, Christopher J. Johnson, Emily Y. Chu, Paul W. Harms, Johann E. Gudjonsson
×Abstract
T follicular helper (Tfh) cells represent an important subset of CD4+ T cells that is crucial to the maturation and differentiation of B cells and the production of high-affinity antibodies. Because B cell activating–factor (BAFF), a vital B cell survival factor, is also crucial to B cell maturation and differentiation, we assessed the effects of BAFF on Tfh cell development and function. We demonstrated that deficiency of BAFF, but not of APRIL, markedly inhibited Tfh cell development, germinal center (GC) formation, and antigen-specific antibody production. The promoting effect of BAFF on Tfh cell development was dependent on expression of BR3 on T cells, and its promoting effect on GC formation was dependent on expression of BR3 on both T cells and B cells. BAFF directly promoted expression of the Tfh cell–characteristic genes via NF-κB signaling. This effect did need BR3 expression. Thus, BAFF not only has direct effects on B cells, but it also has direct effects on Tfh cell differentiation via engagement of BR3, which collectively promoted GC formation and production of high-affinity antibodies. This dual effect of BAFF on B cells and Tfh cells may help explain the clinical utility of BAFF antagonists in the management of certain autoimmune diseases.
Authors
Ye Chen, Maogen Chen, Yu Liu, Qiang Li, Youqiu Xue, Liu Liu, Rongzhen Liang, Yiding Xiong, Jun Zhao, Jingrong Chen, Weidong Lin, Julie Wang, Yun Feng Pan, William Stohl, Song Guo Zheng
×Abstract
Multiple sclerosis (MS) is a complex disease with significant heterogeneity in disease course and progression. Genetic studies have identified numerous loci associated with MS risk, but the genetic basis of disease progression remains elusive. To address this, we leveraged the Collaborative Cross (CC), a genetically diverse mouse strain panel, and experimental autoimmune encephalomyelitis (EAE). The 32 CC strains studied captured a wide spectrum of EAE severity, trajectory, and presentation, including severe-progressive, monophasic, relapsing remitting, and axial rotary–EAE (AR-EAE), accompanied by distinct immunopathology. Sex differences in EAE severity were observed in 6 strains. Quantitative trait locus analysis revealed distinct genetic linkage patterns for different EAE phenotypes, including EAE severity and incidence of AR-EAE. Machine learning–based approaches prioritized candidate genes for loci underlying EAE severity (Abcc4 and Gpc6) and AR-EAE (Yap1 and Dync2h1). This work expands the EAE phenotypic repertoire and identifies potentially novel loci controlling unique EAE phenotypes, supporting the hypothesis that heterogeneity in MS disease course is driven by genetic variation.
Authors
Emily A. Nelson, Anna L. Tyler, Taylor Lakusta-Wong, Karolyn G. Lahue, Katherine C. Hankes, Cory Teuscher, Rachel M. Lynch, Martin T. Ferris, J. Matthew Mahoney, Dimitry N. Krementsov
×Abstract
End-stage liver disease is marked by portal hypertension, systemic elevations in ammonia, and development of hepatocellular carcinoma (HCC). While these clinical consequences of cirrhosis are well described, it remains poorly understood whether hepatic insufficiency and the accompanying elevations in ammonia contribute to HCC carcinogenesis. Using preclinical models, we discovered that ammonia entered the cell through the transporter SLC4A11 and served as a nitrogen source for amino acid and nucleotide biosynthesis. Elevated ammonia promoted cancer stem cell properties in vitro and tumor initiation in vivo. Enhancing ammonia clearance reduced HCC stemness and tumor growth. In patients, elevations in serum ammonia were associated with an increased incidence of HCC. Taken together, this study forms the foundation for clinical investigations using ammonia-lowering agents as potential therapies to mitigate HCC incidence and aggressiveness.
Authors
Ameer L. Elaimy, Marwa O. El-Derany, Jadyn James, Zhuwen Wang, Ashley N. Pearson, Erin A. Holcomb, Amanda K. Huber, Miguel Gijón, Hannah N. Bell, Viraj R. Sanghvi, Timothy L. Frankel, Grace L. Su, Elliot B. Tapper, Andrew W. Tai, Nithya Ramnath, Christopher P. Centonze, Irina Dobrosotskaya, Julie A. Moeller, Alex K. Bryant, David A. Elliott, Enid Choi, Joseph R. Evans, Kyle C. Cuneo, Thomas J. Fitzgerald, Daniel R. Wahl, Meredith A. Morgan, Daniel T. Chang, Max S. Wicha, Theodore S. Lawrence, Yatrik M. Shah, Michael D. Green
×Abstract
Natural killer (NK) cells respond to diseased and allogeneic cells through NKG2A/HLA-E or killer cell immunoglobulin-like receptor (KIR)/HLA-ABC interactions. Correlations between HLA/KIR disparities and kidney transplant pathology suggest an antibody-independent pathogenic role for NK cells in transplantation, but the mechanisms remain unclear. Using CyTOF to characterize recipient peripheral NK cell phenotypes and function, we observed diverse NK cell subsets among participants who responded heterogeneously to allo-stimulators. NKG2A+KIR+ NK cells responded more vigorously than other subsets, and this heightened response persisted after kidney transplantation despite immunosuppression. In test and validation sets from 2 clinical trials, pretransplant donor-induced release of cytotoxicity mediator Ksp37 by NKG2A+ NK cells correlated with reduced long-term allograft function. Separate analyses showed that Ksp37 gene expression in allograft biopsies lacking histological rejection correlated with death-censored graft loss. Our findings support an antibody-independent role for NK cells in transplant injury and support further testing of pretransplant, donor-reactive, NK cell–produced Ksp37 as a risk-assessing, transplantation biomarker.
Authors
Dan Fu Ruan, Miguel Fribourg, Yuko Yuki, Yeon-Hwa Park, Maureen P. Martin, Haocheng Yu, Geoffrey C. Kelly, Brian Lee, Ronaldo M. de Real, Rachel Lee, Daniel Geanon, Seunghee Kim-Schulze, Nicholas Chun, Paolo Cravedi, Mary Carrington, Peter S. Heeger, Amir Horowitz
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Abstract
The cytokine interleukin-18 (IL-18) has immunostimulatory effects but is negatively regulated by a secreted binding protein, IL-18BP, that limits IL-18’s anti-cancer efficacy. A “decoy-resistant” form of IL-18 (DR-18), that avoids sequestration by IL-18BP while maintaining its immunostimulatory potential, has recently been developed. Here, we investigated the therapeutic potential of DR-18 in renal cell carcinoma (RCC). Using pan-tumor transcriptomic data, we found that clear cell RCC had among the highest expression of IL-18 receptor subunits and IL18BP of tumor types in the database. In samples from RCC patients treated with immune checkpoint inhibitors, IL-18BP protein expression increased in the tumor microenvironment and circulating in plasma in non-responding patients and decreased in the majority of responding patients. We used immunocompetent RCC murine models to assess the efficacy of DR-18 in combination with single- and dual-agent anti-PD-1 and anti-CTLA-4. In contrast to preclinical models of other tumor types, in RCC models DR-18 enhanced the activity of anti-CTLA-4 but not anti-PD-1 treatment. This activity correlated with intra-tumoral enrichment and clonal expansion of effector CD8+ T cells, decreased regulatory T cell levels, and enrichment of pro-inflammatory, anti-tumor myeloid cell populations. Our findings support further clinical investigation of the combination of DR-18 and anti-CTLA-4 in RCC.
Authors
David A. Schoenfeld, Dijana Djureinovic, David G. Su, Lin Zhang, Benjamin Y. Lu, Larisa Kamga, Jacqueline E. Mann, John D. Huck, Michael Hurwitz, David A. Braun, Lucia Jilaveanu, Aaron M. Ring, Harriet M. Kluger
Abstract
The degeneration of retinal ganglion cells (RGC) due to mitochondrial dysfunctions manifests optic neuropathy. However, the molecular components of RGC linked to optic neuropathy manifestations remain largely unknown. Here, we identified a novel optic atrophy-causative CRYAB gene encoding a highly conserved major lens protein acting as mitochondrial chaperone and possessing anti-apoptotic activities. The heterozygous CRYAB mutation (c.313G>A, p. Glu105Lys) was cosegregated with autosomal dominant inheritance of optic atrophy in 3 Chinese families. The p.E105K mutation altered the structure and function of CRYAB, including decreased stability, reduced formation of oligomers and decreasing chaperone activity. Coimmunoprecipitation indicated that the p.E105K mutation reduced the interaction of CRYAB with apoptosis-associated cytochrome c and VDAC. The cell lines carrying the p.E105K mutation displayed promoting apoptosis, defective assembly, stability and activities of oxidative phosphorylation system and imbalance of mitochondrial dynamics. Involvement of CRYAB in optic atrophy was confirmed by phenotypic evaluations of Cryabp.E105K knock-in mice. These mutant mice exhibited ocular lesions including changing intra-retina layers, degeneration of RGCs, photoreceptor deficits and abnormal retinal vasculature. Furthermore, Cryab-deficient mice displayed elevated apoptosis and mitochondrial dysfunctions. Our findings provide new insight of pathophysiology of optic atrophy arising from RGC degeneration caused by CRYAB deficiency-induced elevated apoptosis and mitochondrial dysfunctions.
Authors
Chenghui Wang, Liyao Zhang, Zhipeng Nie, Min Liang, Hanqing Liu, Qiuzi Yi, Chunyan Wang, Cheng Ai, Juanjuan Zhang, Yinglong Gao, Yanchun Ji, Min-Xin Guan
Abstract
CD4+ T helper 1 (TH1) cells coordinate adaptive immune responses to intracellular pathogens, including viruses. Key to this function is the ability of TH1 cells to migrate within secondary lymphoid tissues, as well as to sites of inflammation, which relies on signals received through the chemokine receptor CXCR3. CXCR3 expression is driven by the TH1 lineage-defining transcription factor T-bet, and the cytokine-responsive Signal Transducer and Activator of Transcription (STAT) family members STAT1 and STAT4. Here, we identify the Ikaros zinc finger (IkZF) transcription factor Aiolos (Ikzf3) as an additional positive regulator of CXCR3 both in vitro and in vivo using a murine model of influenza virus infection. Mechanistically, we find that Aiolos-deficient CD4+ T cells exhibit decreased expression of key components of the IFNγ/STAT1 signaling pathway, including JAK2 and STAT1. Consequently, Aiolos deficiency results in decreased levels of STAT1 tyrosine phosphorylation and reduced STAT1 enrichment at the Cxcr3 promoter. We further find that Aiolos and STAT1 form a positive feedback loop via reciprocal regulation of each other downstream of IFNγ signaling. Collectively, our study demonstrates that Aiolos promotes CXCR3 expression on TH1 cells by propagating the IFNγ/STAT1 cytokine signaling pathway.
Authors
Melissa R. Leonard, Devin M. Jones, Kaitlin A. Read, Srijana Pokhrel, Jasmine A. Tuazon, Robert T. Warren, Jacob S. Yount, Kenneth J. Oestreich
Abstract
Hepatic macrophages and regulatory T cells (Tregs) play an important role in the maintenance of liver immune homeostasis, but the mechanism by which hepatic macrophages regulate Tregs in acute liver injury remains largely unknown. Here, we found that the hepatic Treg proportion and β-catenin expression in hepatic macrophages were associated with acetaminophen (APAP) and D-galactosamine (D-GalN)/ lipopolysaccharide (LPS)-induced acute liver injury. Interestingly, β-catenin was markedly upregulated only in infiltrating macrophages, but not in resident Kupffer cells. Myeloid-specific β-catenin knockout mice showed an increased inflammatory cell infiltration and hepatocyte apoptosis. Moreover, myeloid β-catenin deficiency decreased the hepatic Treg proportion in the injured liver. Mechanistically, in vitro co-culture experiments revealed that macrophage β-catenin modulated its exosome composition, and influenced Treg differentiation. Using mass spectrometry-based proteomics, we identified that macrophage β-catenin activation increased the level of exosomal α-SNAP, which in turn promoted Treg differentiation. Overall, our findings demonstrated a molecular mechanism that macrophage β-catenin regulated the Treg proportion in the liver by enhancing the expression of exosomal α-SNAP, providing insights into the pathophysiology of acute liver injury.
Authors
Ruobin Zong, Yujie Liu, Mengya Zhang, Buwei Liu, Wei Zhang, Hankun Hu, Changyong Li
Abstract
Bone homeostasis primarily stems from the balance between osteoblasts and osteoclasts, wherein an augmented number or heightened activity of osteoclasts is a prevalent etiological factor in the development of bone loss. Nuclear Dbf2-related kinase (NDR2), also known as STK38L, is a member of the Hippo family with serine/threonine kinase activity. We unveiled an upregulation of NDR2 expression during osteoclast differentiation. Manipulation of NDR2 levels through knockdown or overexpression facilitated or hindered osteoclast differentiation respectively, indicating a negative feedback role for NDR2 in the osteoclastogenesis. Myeloid NDR2-dificient mice (Lysm+NDR2f/f) showed lower bone mass and further exacerbated ovariectomy-induced or aging-related bone loss. Mechanically, NDR2 enhanced autophagy and mitophagy through mediating ULK1 instability. In addition, ULK1 inhibitor (ULK1-IN2) ameliorated NDR2 cKO-induced bone loss. Finally, we clarified a significant inverse association between NDR2 expression and the occurrence of osteoporosis in patients. In a word, NDR2-ULK1-mitophagy axis was a potential innovative therapeutic target for the prevention and management of bone loss.
Authors
Xiangxi Kong, Zhi Shan, Yihao Zhao, Siyue Tao, Jingyun Chen, Zhongyin Ji, Jiayan Jin, Junhui Liu, Wenlong Lin, Xiaojian Wang, Jian Wang, Fengdong Zhao, Bao Huang, Jian Chen
