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Research Articles
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Abstract
Sensing of pathogens by host pattern recognition receptors is essential for activating the immune response during infection. We used a nonlethal murine model of malaria (Plasmodium yoelii 17XNL) to assess the contribution of the pattern recognition receptor cyclic GMP-AMP synthase (cGAS) to the development of humoral immunity. Despite previous reports suggesting a critical, intrinsic role for cGAS in early B cell responses, cGAS-deficient (cGAS–/–) mice had no defect in the early expansion or differentiation of Plasmodium-specific B cells. As the infection proceeded, however, cGAS–/– mice exhibited higher parasite burdens and aberrant germinal center and memory B cell formation when compared with littermate controls. Antimalarial drugs were used to further demonstrate that the disrupted humoral response was not B cell intrinsic but instead was a secondary effect of a loss of parasite control. These findings therefore demonstrate that cGAS-mediated innate-sensing contributes to parasite control but is not intrinsically required for the development of humoral immunity. Our findings highlight the need to consider the indirect effects of pathogen burden in investigations examining how the innate immune system affects the adaptive immune response.
Authors
William O. Hahn, Noah S. Butler, Scott E. Lindner, Holly M. Akilesh, D. Noah Sather, Stefan H.I. Kappe, Jessica A. Hamerman, Michael Gale Jr., W. Conrad Liles, Marion Pepper
×Abstract
Phosphodiesterase 3 (PDE3) and PDE4 regulate levels of cyclic AMP, which are critical in various cell types involved in allergic airway inflammation. Although PDE4 inhibition attenuates allergic airway inflammation, reported side effects preclude its application as an antiasthma drug in humans. Case reports showed that enoximone, which is a smooth muscle relaxant that inhibits PDE3, is beneficial and lifesaving in status asthmaticus and is well tolerated. However, clinical observations also showed antiinflammatory effects of PDE3 inhibition. In this study, we investigated the role of PDE3 in a house dust mite–driven (HDM-driven) allergic airway inflammation (AAI) model that is characterized by T helper 2 cell activation, eosinophilia, and reduced mucosal barrier function. Compared with wild-type (WT) littermates, mice with a targeted deletion of the PDE3A or PDE3B gene showed significantly reduced HDM-driven AAI. Therapeutic intervention in WT mice showed that all hallmarks of HDM-driven AAI were abrogated by the PDE3 inhibitors enoximone and milrinone. Importantly, we found that enoximone also reduced the upregulation of the CD11b integrin on mouse and human eosinophils in vitro, which is crucial for their recruitment during allergic inflammation. This study provides evidence for a hitherto unknown antiinflammatory role of PDE3 inhibition in allergic airway inflammation and offers a potentially novel treatment approach.
Authors
Jan Beute, Melanie Lukkes, Ewout P. Koekoek, Hedwika Nastiti, Keerthana Ganesh, Marjolein J.W. de Bruijn, Steve Hockman, Menno van Nimwegen, Gert-Jan Braunstahl, Louis Boon, Bart N. Lambrecht, Vince C. Manganiello, Rudi W. Hendriks, Alex KleinJan
×Abstract
Late allograft failure is characterized by cumulative subclinical insults manifesting over many years. Although immunomodulatory therapies targeting host T cells have improved short-term survival rates, rates of chronic allograft loss remain high. We hypothesized that other immune cell types may drive subclinical injury, ultimately leading to graft failure. We collected whole-genome transcriptome profiles from 15 independent cohorts composed of 1,697 biopsy samples to assess the association of an inflammatory macrophage polarization–specific gene signature with subclinical injury. We applied penalized regression to a subset of the data sets and identified a 3-gene inflammatory macrophage–derived signature. We validated discriminatory power of the 3-gene signature in 3 independent renal transplant data sets with mean AUC of 0.91. In a longitudinal cohort, the 3-gene signature strongly correlated with extent of injury and accurately predicted progression of subclinical injury 18 months before clinical manifestation. The 3-gene signature also stratified patients at high risk of graft failure as soon as 15 days after biopsy. We found that the 3-gene signature also distinguished acute rejection (AR) accurately in 3 heart transplant data sets but not in lung transplant. Overall, we identified a parsimonious signature capable of diagnosing AR, recognizing subclinical injury, and risk-stratifying renal transplant patients. Our results strongly suggest that inflammatory macrophages may be a viable therapeutic target to improve long-term outcomes for organ transplantation patients.
Authors
Tej D. Azad, Michele Donato, Line Heylen, Andrew B. Liu, Shai S. Shen-Orr, Timothy E. Sweeney, Jonathan Scott Maltzman, Maarten Naesens, Purvesh Khatri
×Abstract
Intraocular injection of adeno-associated viral (AAV) vectors has been an evident route for delivering gene drugs into the retina. However, gaps in our understanding of AAV transduction patterns within the anatomically unique environments of the subretinal and intravitreal space of the primate eye impeded the establishment of noninvasive and efficient gene delivery to foveal cones in the clinic. Here, we establish new vector-promoter combinations to overcome the limitations associated with AAV-mediated cone transduction in the fovea with supporting studies in mouse models, human induced pluripotent stem cell–derived organoids, postmortem human retinal explants, and living macaques. We show that an AAV9 variant provides efficient foveal cone transduction when injected into the subretinal space several millimeters away from the fovea, without detaching this delicate region. An engineered AAV2 variant provides gene delivery to foveal cones with a well-tolerated dose administered intravitreally. Both delivery modalities rely on a cone-specific promoter and result in high-level transgene expression compatible with optogenetic vision restoration. The model systems described here provide insight into the behavior of AAV vectors across species to obtain safety and efficacy needed for gene therapy in neurodegenerative disorders.
Authors
Hanen Khabou, Marcela Garita-Hernandez, Antoine Chaffiol, Sacha Reichman, Céline Jaillard, Elena Brazhnikova, Stéphane Bertin, Valérie Forster, Mélissa Desrosiers, Céline Winckler, Olivier Goureau, Serge Picaud, Jens Duebel, José-Alain Sahel, Deniz Dalkara
×Abstract
Several imaging modalities have been used to assess lymphatic function, including fluorescence microscopy, near-infrared fluorescence (NIRF) imaging, and Doppler optical coherence tomography (DOCT). They vary in how the mouse is positioned, the invasiveness of the experimental setup, and the volume of contrast agent injected. Here, we present how each of these experimental parameters affects functional measurements of collecting lymphatic vessels. First, fluorescence microscopy showed that supine mice have a statistically lower contraction frequency compared with mice sitting upright. To assess the effect of different injection volumes on these endpoints, mice were injected with 4, 10, or 20 μl of dye. The lowest frequencies were observed after 20-μl injections. Interestingly, lymph-flow DOCT revealed that although there was lower contraction frequency in mice injected with 20 μl versus 4 μl, mice showed a higher volumetric flow with a 20-μl injection. This indicates that contraction frequency alone is not sufficient to understand lymphatic transport. Finally, NIRF revealed that removing the skin reduced contraction frequency. Therefore, this study reveals how sensitive these techniques are to mouse position, removal of skin, and dye volume. Care should be taken when comparing results obtained under different experimental conditions.
Authors
Echoe M. Bouta, Cedric Blatter, Thomas A. Ruggieri, Eelco F.J. Meijer, Lance L. Munn, Benjamin J. Vakoc, Timothy P. Padera
×Abstract
Signaling through IL-2/IL-15Rβ (CD122) is essential for the differentiation and function of T cells and NK cells. A mAb against CD122 has been implicated to suppress autoimmune type 1 diabetes (T1D) development in animal models. However, the mechanisms remain poorly understood. We find that in vivo administration of an anti-CD122 mAb (CD122 blockade) restores immune tolerance in nonobese diabetic (NOD) mice via multiple mechanisms. First, CD122 blockade selectively ablates pathogenic NK cells and memory phenotype CD8+ T cells from pancreatic islets. In contrast, islet CD4+Foxp3+ Tregs are only mildly affected. Second, CD122 blockade suppresses IFN-γ production in islet immune cells. Third, CD122 blockade inhibits the conversion of islet Th17 cells into diabetogenic Th1 cells. Furthermore, a combination of anti-CD122 mAb and Treg-trophic cytokines (IL-2 or IL-33) enhances the abundance and function of islet Tregs. In summary, these data provide crucial mechanistic insights into CD122 blockade–mediated immunoregulation and support therapeutic benefits of this combinational treatment in T1D.
Authors
Xiaomei Yuan, Yi Dong, Naoya Tsurushita, J. Yun Tso, Wenxian Fu
×Abstract
Mesenchymal stem cells (MSCs) can give rise to both adipocytes and osteoblasts, but the molecular mechanisms underlying MSC fate determination remain poorly understood. IκB kinase β (IKKβ), a central coordinator of inflammation and immune responses through activation of NF-κB, has been implicated as a critical molecular link between obesity and metabolic disorders. Here, we show that IKKβ can reciprocally regulate adipocyte and osteoblast differentiation of murine and human MSCs through an NF-κB–independent mechanism. IKKβ is a β-catenin kinase that phosphorylates the conserved degron motif of β-catenin to prime it for β-TrCP–mediated ubiquitination and degradation, thereby increasing adipogenesis and inhibiting osteogenesis in MSCs. Animal studies demonstrated that deficiency of IKKβ in BM mesenchymal stromal cells increased bone mass and decreased BM adipocyte formation in adult mice. In humans, IKKβ expression in adipose tissue was also positively associated with increased adiposity and elevated β-catenin phosphorylation. These findings suggest IKKβ as a key molecular switch that regulates MSC fate, and they provide potentially novel mechanistic insights into the understanding of the cross-regulation between the evolutionarily conserved IKKβ and Wnt/β-catenin signaling pathways. The IKKβ-Wnt axis we uncovered may also have important implications for development, homeostasis, and disease pathogenesis.
Authors
Yipeng Sui, Zun Liu, Se-Hyung Park, Sean E. Thatcher, Beibei Zhu, Joseph P. Fernandez, Henrik Molina, Philip A. Kern, Changcheng Zhou
×Abstract
A DNA methylation (DNAm) signature (the “Horvath clock”) has been proposed as a measure of human chronological and biological age. We determined peripheral blood DNAm in patients with nonalcoholic steatohepatitis (NASH) and assessed whether accelerated aging occurs in these patients. DNAm signatures were obtained in patients with biopsy-proven NASH and stage 2–3 fibrosis. The DNAm profile from one test and two validation cohorts served as controls. Age acceleration was calculated as the difference between DNAm age and the predicted age based on the linear model derived from controls. Hepatic collagen content was assessed by quantitative morphometry. The Horvath clock accurately predicts the chronological age of the entire cohort. Age acceleration was observed among NASH subjects compared with control data sets and our test controls. Age acceleration in NASH subjects did not differ by fibrosis stage but correlated with hepatic collagen content. A set of 152 differentially methylated CpG islands between NASH subjects and controls identified gene set enrichment for transcription factors and developmental pathways. Patients with NASH exhibit epigenetic age acceleration that correlates with hepatic collagen content.
Authors
Rohit Loomba, Yevgeniy Gindin, Zhaoshi Jiang, Eric Lawitz, Stephen Caldwell, C. Stephen Djedjos, Ren Xu, Chuhan Chung, Robert P. Myers, G. Mani Subramanian, Zachary Goodman, Michael Charlton, Nezam H. Afdhal, Anna Mae Diehl
×Abstract
T cell receptor (TCR) affinity is a critical factor of Treg lineage commitment, but whether self-reactivity is a determining factor in peripheral Treg function remains unknown. Here, we report that a high degree of self-reactivity is crucial for tissue-specific Treg function in autoimmunity. Based on high expression of CD5, we identified a subset of self-reactive Tregs expressing elevated levels of T-bet, GITR, CTLA-4, and ICOS, which imparted significant protection from autoimmune diabetes. We observed that T-bet expression in Tregs, necessary for control of Th1 autoimmunity, could be induced in an IFNγ-independent fashion and, unlike in conventional T cells (Tconv), was strongly correlated with the strength of TCR signaling. The level of CD5 similarly identified human Tregs with an increased functional profile, suggesting that CD5hi Tregs may constitute an efficacious subpopulation appropriate for use in adoptive Treg therapies for treatment of inflammatory conditions. Overall, this work establishes an instrumental role of high TCR self-reactivity in driving Treg function.
Authors
Maran L. Sprouse, Marissa A. Scavuzzo, Samuel Blum, Ivan Shevchenko, Thomas Lee, George Makedonas, Malgorzata Borowiak, Matthew L. Bettini, Maria Bettini
×Mutant p53R270H drives altered metabolism and increased invasion in pancreatic ductal adenocarcinoma
Abstract
Pancreatic cancer is characterized by nearly universal activating mutations in KRAS. Among other somatic mutations, TP53 is mutated in more than 75% of human pancreatic tumors. Genetically engineered mice have proven instrumental in studies of the contribution of individual genes to carcinogenesis. Oncogenic Kras mutations occur early during pancreatic carcinogenesis and are considered an initiating event. In contrast, mutations in p53 occur later during tumor progression. In our model, we recapitulated the order of mutations of the human disease, with p53 mutation following expression of oncogenic Kras. Further, using an inducible and reversible expression allele for mutant p53, we inactivated its expression at different stages of carcinogenesis. Notably, the function of mutant p53 changes at different stages of carcinogenesis. Our work establishes a requirement for mutant p53 for the formation and maintenance of pancreatic cancer precursor lesions. In tumors, mutant p53 becomes dispensable for growth. However, it maintains the altered metabolism that characterizes pancreatic cancer and mediates its malignant potential. Further, mutant p53 promotes epithelial-mesenchymal transition (EMT) and cancer cell invasion. This work generates new mouse models that mimic human pancreatic cancer and expands our understanding of the role of p53 mutation, common in the majority of human malignancies.
Authors
Heather K. Schofield, Jörg Zeller, Carlos Espinoza, Christopher J. Halbrook, Annachiara del Vecchio, Brian Magnuson, Tania Fabo, Ayse Ece Cali Daylan, Ilya Kovalenko, Ho-Joon Lee, Wei Yan, Ying Feng, Saadia A. Karim, Daniel M. Kremer, Chandan Kumar-Sinha, Costas A. Lyssiotis, Mats Ljungman, Jennifer P. Morton, Stefanie Galbán, Eric R. Fearon, Marina Pasca di Magliano
×Abstract
We identify 2 homozygous mutations in the ε-subunit of the muscle acetylcholine receptor (AChR) in 3 patients with severe congenital myasthenia: εR218W in the pre-M1 region in 2 patients and εE184K in the β8-β9 linker in 1 patient. Arg218 is conserved in all eukaryotic members of the Cys-loop receptor superfamily, while Glu184 is conserved in the α-, δ-, and ε-subunits of AChRs from all species. εR218W reduces channel gating efficiency 338-fold and AChR expression on the cell surface 5-fold, whereas εE184K reduces channel gating efficiency 11-fold but does not alter AChR cell surface expression. Determinations of the effective channel gating rate constants, combined with mutant cycle analyses, demonstrate strong energetic coupling between εR218 and εE184, and between εR218 and εE45 from the β1-β2 linker, as also observed for equivalent residues in the principal coupling pathway of the α-subunit. Thus, efficient and rapid gating of the AChR channel is achieved not only by coupling between conserved residues within the principal coupling pathway of the α-subunit, but also between corresponding residues in the ε-subunit.
Authors
Xin-Ming Shen, Joan M. Brengman, Shelley Shen, Hacer Durmus, Veeramani Preethish-Kumar, Nur Yuceyar, Seena Vengalil, Atchayaram Nalini, Feza Deymeer, Steven M. Sine, Andrew G. Engel
×Abstract
The adrenal cortex undergoes remodeling during fetal and postnatal life. How zona reticularis emerges in the postnatal gland to support adrenarche, a process whereby higher primates increase prepubertal androgen secretion, is unknown. Using cell-fate mapping and gene deletion studies in mice, we show that activation of PKA has no effect on the fetal cortex, while it accelerates regeneration of the adult cortex, triggers zona fasciculata differentiation that is subsequently converted into a functional reticularis-like zone, and drives hypersecretion syndromes. Remarkably, PKA effects are influenced by sex. Indeed, testicular androgens increase WNT signaling that antagonizes PKA, leading to slower adrenocortical cell turnover and delayed phenotype whereas gonadectomy sensitizes males to hypercorticism and reticularis-like formation. Thus, reticularis results from ultimate centripetal conversion of adult cortex under the combined effects of PKA and cell turnover that dictate organ size. We show that PKA-induced progenitor recruitment is sexually dimorphic and may provide a paradigm for overrepresentation of women in adrenal diseases.
Authors
Typhanie Dumontet, Isabelle Sahut-Barnola, Amandine Septier, Nathanaëlle Montanier, Ingrid Plotton, Florence Roucher-Boulez, Véronique Ducros, Anne-Marie Lefrançois-Martinez, Jean-Christophe Pointud, Mohamad Zubair, Ken-Ichirou Morohashi, David T. Breault, Pierre Val, Antoine Martinez
×Abstract
Primary graft dysfunction (PGD) is acute lung injury within 72 hours of lung transplantation. We hypothesized that cell-free hemoglobin (CFH) contributes to PGD by increasing lung microvascular permeability and tested this in patients, ex vivo human lungs, and cultured human lung microvascular endothelial cells. In a nested case control study of 40 patients with severe PGD at 72 hours and 80 matched controls without PGD, elevated preoperative CFH was independently associated with increased PGD risk (odds ratio [OR] 2.75, 95%CI, 1.23–6.16, P = 0.014). The effect of CFH on PGD was magnified by reperfusion fraction of inspired oxygen (FiO2) ≥ 0.40 (OR 3.41, P = 0.031). Isolated perfused human lungs exposed to intravascular CFH (100 mg/dl) developed increased vascular permeability as measured by lung weight (CFH 14.4% vs. control 0.65%, P = 0.047) and extravasation of Evans blue–labeled albumin dye (EBD) into the airspace (P = 0.027). CFH (1 mg/dl) also increased paracellular permeability of human pulmonary microvascular endothelial cell monolayers (hPMVECs). Hyperoxia (FiO2 = 0.95) increased human lung and hPMVEC permeability compared with normoxia (FiO2 = 0.21). Treatment with acetaminophen (15 μg/ml), a specific hemoprotein reductant, prevented CFH-dependent permeability in human lungs (P = 0.046) and hPMVECs (P = 0.037). In summary, CFH may mediate PGD through oxidative effects on microvascular permeability, which are augmented by hyperoxia and abrogated by acetaminophen.
Authors
Ciara M. Shaver, Nancy Wickersham, J. Brennan McNeil, Hiromasa Nagata, Adam Miller, Stuart R. Landstreet, Jamie L. Kuck, Joshua M. Diamond, David J. Lederer, Steven M. Kawut, Scott M. Palmer, Keith M. Wille, Ann Weinacker, Vibha N. Lama, Maria M. Crespo, Jonathan B. Orens, Pali D. Shah, Chadi A. Hage, Edward Cantu III, Mary K. Porteous, Gundeep Dhillon, John McDyer, Julie A. Bastarache, Jason D. Christie, Lorraine B. Ware, the Lung Transplant Outcomes Group (LTOG)
×Abstract
Incomplete penetrance of congenital heart defects (CHDs) was observed in a mouse model. We hypothesized that the contribution of a major genetic locus modulates the manifestation of the CHDs. After genome-wide linkage mapping, fine mapping, and high-throughput targeted sequencing, a recessive frameshift mutation of the heterogeneous nuclear ribonucleoprotein A1 (Hnrnpa1) gene was confirmed (Hnrnpa1ct). Hnrnpa1 was expressed in both the first heart field (FHF) and second heart field (SHF) at the cardiac crescent stage but was only maintained in SHF progenitors after heart tube formation. Hnrnpa1ct/ct homozygous mutants displayed complete CHD penetrance, including truncated and incomplete looped heart tube at E9.5, ventricular septal defect (VSD) and persistent truncus arteriosus (PTA) at E13.5, and VSD and double outlet right ventricle at P0. Impaired development of the dorsal mesocardium and sinoatrial node progenitors was also observed. Loss of Hnrnpa1 expression leads to dysregulation of cardiac transcription networks and multiple signaling pathways, including BMP, FGF, and Notch in the SHF. Finally, two rare heterozygous mutations of HNRNPA1 were detected in human CHDs. These findings suggest a role of Hnrnpa1 in embryonic heart development in mice and humans.
Authors
Zhe Yu, Paul L.F. Tang, Jing Wang, Suying Bao, Joseph T. Shieh, Alan W.L. Leung, Zhao Zhang, Fei Gao, Sandra Y.Y. Wong, Andy L.C. Hui, Yuan Gao, Nelson Dung, Zhi-Gang Zhang, Yanhui Fan, Xueya Zhou, Yalun Zhang, Dana S.M. Wong, Pak C. Sham, Abid Azhar, Pui-Yan Kwok, Patrick P.L. Tam, Qizhou Lian, Kathryn S.E. Cheah, Binbin Wang, You-Qiang Song
