Research
Abstract
The mechanism controlling long-chain fatty acid (LCFA) mobilization from adipose tissue (AT) is not well understood. Here, we investigated how the LCFA transporter CD36 regulates this process. By using tissue-specific knockout mouse models, we show that CD36 in both adipocytes and endothelial cells mediates both LCFA deposition into and release from AT. We demonstrate the role of adipocytic and endothelial CD36 in promoting tumor growth and chemoresistance conferred by AT-derived LCFA. We show that dynamic cysteine S-acylation of CD36 in adipocytes, endothelial cells, and cancer cells mediates intercellular LCFA transport. We demonstrate that lipolysis induction in adipocytes triggers CD36 de-acylation and deglycosylation, as well as its dissociation from interacting proteins, prohibitin-1 (PHB), and annexin 2 (ANX2). Our data indicate that lipolysis triggers caveolar endocytosis and translocation of CD36 from the cell membrane to lipid droplets. This study suggests a mechanism for both outside-in and inside-out cellular LCFA transport regulated by CD36 S- acylation and its interactions with PHB and ANX2.
Authors
Alexes C. Daquinag, Zhanguo Gao, Cale Fussell, Linnet Immaraj, Renata Pasqualini, Wadih Arap, Askar M. Akimzhanov, Maria Febbraio, Mikhail G. Kolonin
Abstract
Immunotherapies are needed in the clinic that effectively suppress beta cell autoimmunity and reestablish long-term self-tolerance in type 1 diabetes. We previously demonstrated that nondepleting αCD4 and αCD8α antibodies establish rapid and indefinite remission in recent-onset diabetic NOD mice. Diabetes reversal by coreceptor therapy (CoRT) is induced by suppression of pathogenic effector T cells (Teff) and the selective egress of T cells from the pancreatic lymph nodes and islets that remain free of infiltration long-term. Here, we defined CoRT-induced events regulating early Teff function and pancreatic residency, and long-term tolerance. TCR-driven gene expression controlling autoreactive Teff expansion and proinflammatory activity was suppressed by CoRT, and islet T cell egress was sphingosine-1 phosphate-dependent. In both murine and human T cells, CoRT upregulated the Foxo1 transcriptional axis, which in turn was required for suppression and efficient pancreatic egress of Teff. Interestingly, long-term tolerance induced in late-preclinical NOD mice was marked by reseeding of the pancreas by a reduced CD8+ Teff pool exhibiting an exhausted phenotype. Notably, PD-1 blockade, which rescues exhausted Teff, resulted in diabetes onset in protected animals. These findings demonstrate that CoRT has distinct intrinsic effects on Teff that impact events early in induction and later in maintenance of self-tolerance.
Authors
Matthew Clark, Charles J. Kroger, Qi Ke, Rui Zhang, Karen Statum, J. Justin Milner, Aaron J. Martin, Bo Wang, Roland Tisch
Abstract
Hyperstimulation of the cholecystokinin receptor (CCK1R), a Gq-protein coupled receptor (GPCR), in pancreatic acinar cells is commonly used to induce pancreatitis in rodents. Human pancreatic acinar cells lack CCK1R but express cholinergic receptor muscarinic 3 (M3R), another GPCR. To test whether M3R activation is involved in pancreatitis, a mutant M3R was conditionally expressed in pancreatic acinar cells in mice. This mutant receptor loses responsiveness to its native ligand acetylcholine but can be activated by an inert small molecule, clozapine-N-oxide (CNO). Intracellular calcium and amylase were elicited by CNO in pancreatic acinar cells isolated from mutant M3R mice but not WT mice. Similarly, acute pancreatitis (AP) could be induced by a single injection of CNO in the transgenic mice but not WT mice. Compared with the cerulein-induced AP, CNO caused more widespread acinar cell death and inflammation. Furthermore, chronic pancreatitis developed at 4 weeks after 3 episodes of CNO-induced AP. In contrast, in mice with three recurrent episodes of cerulein-included AP, pancreas histology was restored in 4 weeks. Furthermore, the M3R antagonist ameliorated the severity of cerulein-induced AP in WT mice. We conclude that M3R activation can cause the pathogenesis of pancreatitis. This model may provide an alternative approach for pancreatitis research.
Authors
Jianhua Wan, Jiale Wang, Larry E. Wagner II, Oliver H. Wang, Fu Gui, Jiaxiang Chen, Xiaohui Zhu, Ashley N. Haddock, Brandy H. Edenfield, Brian Haight, Debabrata Mukhopadhyay, Ying Wang, David I. Yule, Yan Bi, Baoan Ji
Abstract
Lack of sustained response to therapeutic agents in patients with KRAS mutant lung cancer poses a major challenge and arises partly due to intratumor heterogeneity that defines phenotypically distinct tumor subpopulations. To attain better therapeutic outcomes it is important to understand the differential therapeutic sensitivities of tumor cell subsets. Epithelial-to-mesenchymal transition (EMT) is a biologic phenomenon that can alter the state of cells along a phenotypic spectrum and cause transcriptional rewiring to produce distinct tumor cell subpopulations. We utilized functional shRNA screens, in vitro and in vivo models to identify and confirm an increased dependence of mesenchymal tumor cells on CDK4 for survival, as well as a mechanism of resistance to MEK inhibitors. High ZEB1 levels in mesenchymal tumor cells repressed p21, leading to perturbed CDK4 pathway activity. Increased dependence on CDK4 rendered mesenchymal cancer cells particularly vulnerable to selective CDK4 inhibitors. Co-administration of CDK4 and MEK inhibitors in heterogeneous tumors effectively targeted different tumor subpopulations, subverting the resistance to either single agent treatment.
Authors
Aparna Padhye, Jessica M. Konen, B. Leticia Rodriguez, Jared J. Fradette, Joshua K. Ochieng, Lixia Diao, Jing Wang, Wei Lu, Luisa S. Solis, Harsh Batra, Maria G. Raso, Michael D. Peoples, Rosalba Minelli, Alessandro Carugo, Christopher A. Bristow, Don L. Gibbons
Abstract
The metabolic environment is important for neuronal cells, such as photoreceptors. When photoreceptors undergo degeneration, as occurs during retinitis pigmentosa (RP), patients have progressive loss of vision that proceeds to full blindness. Currently, there are no available treatments for the majority of RP diseases. We performed metabolic profiling of the neural retina in a preclinical model of RP and found that tricarboxylic acid (TCA) cycle intermediates were reduced during disease. We then determined that, 1) promoting citrate production within the TCA cycle in retinal neurons during disease progression protects the photoreceptors from cell death and prolongs visual function, 2) that supplementation with single metabolites within the TCA cycle can provide this therapeutic effect in vivo over time, and, 3) that this therapeutic effect is not specific to a particular genetic mutation but has broad applicability for patients with RP and other retinal degenerative diseases. Overall, targeting TCA cycle activity in the neural retina promotes photoreceptor survival and visual function during neurodegenerative disease.
Authors
Ashley A. Rowe, Pinkal D. Patel, Ruth Gordillo, Katherine J. Wert
Abstract
Aging is associated with chronic oxidative stress and inflammation that impact the tissue repair and regeneration capacity. MG53 is a TRIM family protein that facilitates repair of cell membrane injury in a redox-dependent manner. Here we demonstrate that the expression of MG53 is reduced in failing human heart and aging mouse heart, concomitant with elevated NFκB activation. We evaluate the safety and efficacy of longitudinal, systemic administration of recombinant human MG53 (rhMG53) protein in aged mice. Echocardiography and pressure-volume loop measurements reveal beneficial effects of rhMG53 treatment in improving heart function of aging mice. Biochemical and histological studies demonstrate the cardioprotective effects of rhMG53 are linked to suppression of NFκB-mediated inflammation, reducing apoptotic cell death and oxidative stress in the aged heart. Repetitive administrations of rhMG53 in aged mice do not have adverse effects on major vital organ functions. These findings support the therapeutic value of rhMG53 in treating age-related decline in cardiac function.
Authors
Xiaoliang Wang, Xiuchun Li, Hannah Ong, Tao Tan, Ki Ho Park, Zehua Bian, Xunchang Zou, Erin Haggard, Paul M. Janssen, Robert E. Merritt, Timothy M. Pawlik, Bryan A. Whitson, Nahush A. Mokadam, Lei Cao, Hua Zhu, Chuanxi Cai, Jianjie Ma
Abstract
Retinoic Acid (RA) signaling has long been speculated to regulate embryo implantation, because many enzymes and proteins responsible for maintaining RA homeostasis and transducing RA signals are tightly regulated in the endometrium during this critical period. However, due to lack of genetic data, it was unclear whether RA signaling is truly required for implantation, and which specific RA signaling cascades are at play. Herein we utilize a genetic murine model that expresses a dominant negative form of RA receptor specifically in female reproductive organs to show that functional RA signaling is fundamental to female fertility, particularly implantation and decidualization. Reduction in RA signaling activity severely affects the ability of the uterus to achieve receptive status and decidualize, partially through dampening follistatin expression and downstream activin B/BMP2 signaling. To confirm translational relevance of these findings to humans, human endometrial stromal cells (hESCs) were treated with pan-RAR antagonist to show that in vitro decidualization is impaired. RNAi perturbation of individual RAR transcripts in hESCs revealed that RARα in particular is essential for proper decidualization. These data provide direct functional evidence that uterine RAR-mediated RA signaling is crucial for mammalian embryo implantation, and its disruption leads to failure of uterine receptivity and decidualization resulting in severely compromised fertility.
Authors
Yan Yin, Meade E. Haller, Sangappa B. Chadchan, Ramakrishna Kommagani, Liang Ma
Abstract
Host genes define the severity of inflammation and immunity but specific loci doing so are unknown. Here we show that TNFRSF13B variants which enhance defense against certain pathogens, also control immune-mediated injury of transplants, by regulating innate B cells’ functions. Analysis of TNFRSF13B in human kidney transplant recipients revealed that 33% of the subjects with antibody-mediated rejection (AMR) but less than 6% of those with stable graft function had TNFRSF13B missense mutations. To explore mechanisms underlying aggressive immune responses we investigated allo-immunity and rejection in mice. Cardiac allografts in Tnfrsf13b-mutant mice underwent early and severe AMR. The dominance and precocity of AMR in Tnfrsf13b-deficient mice was not caused by increased alloantibodies. Rather, Tnfrsf13b mutations decreased “natural” IgM and compromised complement regulation leading to complement deposition in allografted hearts and autogenous kidneys. Thus, wild type TNFRSF13B and Tnfrsf13b support innate B cell functions that limit complement-associated inflammation; in contrast, common variants of these genes, intensify inflammatory responses that help clear microbial infections but allow inadvertent tissue injury to ensue. The wide variation in inflammatory reactions associated with TNFRSF13B diversity suggests polymorphisms could underlie variation in host defense and explosive inflammatory responses that sometimes enhances morbidity associated with immune responses.
Authors
Mayara Garcia de Mattos Barbosa, Adam R. Lefferts, Daniel Huynh, Hui Liu, Yu Zhang, Beverly Fu, Jenna Barnes, Milagros Samaniego, Richard J. Bram, Raif Geha, Ariella Shikanov, Eline T. Luning Prak, Evan A. Farkash, Jeffrey L. Platt, Marilia Cascalho
Abstract
Rationale. The importance of the adaptative T cell response in the control and resolution of viral infection has been well-established. However, the nature of T cell-mediated viral control mechanisms in life-threatening stages of COVID-19 has yet to be determined. Objective. The aim of the present study was to determine the function and phenotype of T cell populations associated with survival or death of COVID-19 patients under intensive care as a result of phenotypic and functional profiling by mass cytometry. Findings. Increased frequencies of circulating, polyfunctional, CD4+CXCR5+HLA-DR+ stem cell memory T cells (TSCM) and decreased proportions of Granzyme-B and Perforin-expressing effector memory T cells (TEM) were detected in recovered and deceased patients, respectively. The higher abundance of polyfunctional CD8+PD-L1+CXCR3+ T effector cells, CXCR5+HLA-DR+ TSCM, as well as anti-nucleocapsid (NC) cytokine-producing T cells permitted to differentiate between recovered and deceased patients. The results from a principal component analysis showed an imbalance in the T cell compartment allowed for the separation of recovered and deceased patients. The paucity of circulating CD8+PD-L1+CXCR3+ Teff-cells and NC-specific CD8+ T-cells accurately forecasts fatal disease outcome. Conclusion. This study provides insight into the nature of the T cell populations involved in the control of COVID-19 and therefor might impact T cell-based vaccine designs for this infectious disease.
Authors
Lucille Adam, Pierre Rosenbaum, Paul Quentric, Christophe Parizot, Olivia Bonduelle, Noëlline Guillou, Aurelien Corneau, Karim Dorgham, Makoto Miyara, Charles-Edouard Luyt, Amélie Guihot, Guy Gorochov, Christophe Combadière, Behazine Combadière
Abstract
γδ T cell is a promising candidate cell in tumor immunotherapy. However, γδ T cells polarized to CD39+γδ Tregs upon colorectal cancer (CRC) induction and the underlying mechanism remains unclear. Here, we discovered that the frequency of CD39+γδ Tregs, which positively correlated with poor prognosis, was significantly higher in right-sided CRC (RSCRC) than in the left-sided CRC (LSCRC). Interestingly, CD39+γδ Tregs from RSCRC showed stronger immunosuppressive phenotype and function than LSCRC. Further, the quantitative mass spectrometry data showed that CD39+γδ Tregs polarization was related to the abnormal activation of the PLA2G4A/AA metabolic pathway in RSCRC. Using an in vitro co-culture system and an orthotopic murine model of CRC, we proved that the overexpression of Pla2g4a in CT26 cells induced CD39+γδ Tregs inhibiting the anti-tumor immune response. Finally, we found that the overall survival of the PLA2G4Ahigh group was significantly shortened compared to PLA2G4Alow RSCRC, while the survival of LSCRC was on the contrary. Collectively, RSCRC with abnormal PLA2G4A expression educates γδ T cells into CD39+γδ Tregs to promote tumor progression and metastasis. Our work highlights the interaction between cancer cells and immune cells by distinguishing the primary tumor site and deepens the understanding of tumor microenvironment and immunosuppression.
Authors
Yang Zhan, Lei Zheng, Jia Liu, Dongzhi Hu, Junfeng Wang, Kai Liu, Jiansheng Guo, Ti Zhang, Dalu Kong
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