Latest issue: September 17, 2020

In the issue

Abstract

Classical dynamins are large GTPases regulating membrane and cytoskeleton dynamics, and they are linked to different pathological conditions ranging from neuromuscular diseases to encephalopathy and cancer. Dominant dynamin 2 (DNM2) mutations lead to either mild adult onset or severe autosomal dominant centronuclear myopathy (ADCNM). Our objectives were to better understand the pathomechanism of severe ADCNM and test a potential therapy. Here, we created the Dnm2SL/+ mouse line harboring the common S619L mutation found in patients with severe ADCNM and impairing the conformational switch regulating dynamin self-assembly and membrane remodeling. The Dnm2SL/+ mouse faithfully reproduces severe ADCNM hallmarks with early impaired muscle function and force, together with myofiber hypotrophy. It revealed swollen mitochondria lacking cristae as the main ultrastructural defect and potential cause of the disease. Patient analysis confirmed this structural hallmark. In addition, DNM2 reduction with antisense oligonucleotides after disease onset efficiently reverted locomotor and force defects after only 3 weeks of treatment. Most histological defects including mitochondria alteration were partially or fully rescued. Overall, this study highlights an efficient approach to revert the severe form of dynamin-related centronuclear myopathy. These data also reveal that the dynamin conformational switch is key for muscle function and should be targeted for future therapeutic developments.

Authors

Xènia Massana Muñoz, Christine Kretz, Roberto Silva-Rojas, Julien Ochala, Alexia Menuet, Norma B. Romero, Belinda S. Cowling, Jocelyn Laporte

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Abstract

Specialized proresolving mediators (SPMs) actively limit inflammation and expedite its resolution by modulating leukocyte recruitment and function. Here we profiled intramuscular lipid mediators via liquid chromatography-tandem mass spectrometry–based metabolipidomics following myofiber injury and investigated the potential role of SPMs in skeletal muscle inflammation and repair. Both proinflammatory eicosanoids and SPMs increased following myofiber damage induced by either intramuscular injection of barium chloride or synergist ablation–induced functional muscle overload. Daily systemic administration of the SPM resolvin D1 (RvD1) as an immunoresolvent limited the degree and duration of inflammation, enhanced regenerating myofiber growth, and improved recovery of muscle strength. RvD1 suppressed inflammatory cytokine expression, enhanced polymorphonuclear cell clearance, modulated the local muscle stem cell response, and polarized intramuscular macrophages to a more proregenerative subset. RvD1 had minimal direct impact on in vitro myogenesis but directly suppressed myokine production and stimulated macrophage phagocytosis, showing that SPMs can modulate both infiltrating myeloid and resident muscle cell populations. These data reveal the efficacy of immunoresolvents as a novel alternative to classical antiinflammatory interventions in the management of muscle injuries to modulate inflammation while stimulating tissue repair.

Authors

James F. Markworth, Lemuel A. Brown, Eunice Lim, Carolyn Floyd, Jacqueline Larouche, Jesus A. Castor-Macias, Kristoffer B. Sugg, Dylan C. Sarver, Peter C.D. Macpherson, Carol Davis, Carlos A. Aguilar, Krishna Rao Maddipati, Susan V. Brooks

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Abstract

BACKGROUND Tuberculosis (TB) kills more people than any other infection, and new diagnostic tests to identify active cases are required. We aimed to discover and verify novel markers for TB in nondepleted plasma.METHODS We applied an optimized quantitative proteomics discovery methodology based on multidimensional and orthogonal liquid chromatographic separation combined with high-resolution mass spectrometry to study nondepleted plasma of 11 patients with active TB compared with 10 healthy controls. Prioritized candidates were verified in independent UK (n = 118) and South African cohorts (n = 203).RESULTS We generated the most comprehensive TB plasma proteome to date, profiling 5022 proteins spanning 11 orders-of-magnitude concentration range with diverse biochemical and molecular properties. We analyzed the predominantly low–molecular weight subproteome, identifying 46 proteins with significantly increased and 90 with decreased abundance (peptide FDR ≤ 1%, q ≤ 0.05). Verification was performed for novel candidate biomarkers (CFHR5, ILF2) in 2 independent cohorts. Receiver operating characteristics analyses using a 5-protein panel (CFHR5, LRG1, CRP, LBP, and SAA1) exhibited discriminatory power in distinguishing TB from other respiratory diseases (AUC = 0.81).CONCLUSION We report the most comprehensive TB plasma proteome to date, identifying novel markers with verification in 2 independent cohorts, leading to a 5-protein biosignature with potential to improve TB diagnosis. With further development, these biomarkers have potential as a diagnostic triage test.FUNDING Colciencias, Medical Research Council, Innovate UK, NIHR, Academy of Medical Sciences, Program for Advanced Research Capacities for AIDS, Wellcome Centre for Infectious Diseases Research.

Authors

Diana J. Garay-Baquero, Cory H. White, Naomi F. Walker, Marc Tebruegge, Hannah F. Schiff, Cesar Ugarte-Gil, Stephen Morris-Jones, Ben G. Marshall, Antigoni Manousopoulou, John Adamson, Andres F. Vallejo, Magdalena K. Bielecka, Robert J. Wilkinson, Liku B. Tezera, Christopher H. Woelk, Spiros D. Garbis, Paul Elkington

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Abstract

BACKGROUND Baseline expression of FCRL5, a marker of naive and memory B cells, was shown to predict response to rituximab (RTX) in rheumatoid arthritis. This study investigated baseline expression of FCRL5 as a potential biomarker of clinical response to RTX in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).METHODS A previously validated quantitative PCR–based (qPCR-based) platform was used to assess FCRL5 expression in patients with GPA/MPA (RAVE trial, NCT00104299).RESULTS Baseline FCRL5 expression was significantly higher in patients achieving complete remission (CR) at 6, 12, and 18 months, independent of other clinical and serological variables, among those randomized to RTX but not cyclophosphamide-azathioprine (CYC/AZA). Patients with baseline FCRL5 expression ≥ 0.01 expression units (termed FCRL5hi) exhibited significantly higher CR rates at 6, 12, and 18 months as compared with FCRL5lo subjects (84% versus 57% [P = 0.016], 68% versus 40% [P = 0.02], and 68% versus 29% [P = 0.0009], respectively).CONCLUSION Our data taken together suggest that FCRL5 is a biomarker of B cell lineage associated with increased achievement and maintenance of complete remission among patients treated with RTX and warrant further investigation in a prospective manner.FUNDING The analysis for this study was funded by Genentech Inc.

Authors

Kasia Owczarczyk, Matthew D. Cascino, Cecile Holweg, Gaik W. Tew, Ward Ortmann, Timothy Behrens, Thomas Schindler, Carol A. Langford, E. William St. Clair, Peter A. Merkel, Robert Spiera, Philip Seo, Cees G.M. Kallenberg, Ulrich Specks, Noha Lim, John Stone, Paul Brunetta, Marco Prunotto, the RAVE-ITN Research Group

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Abstract

Despite advances in identifying the key immunoregulatory roles of many of the human leukocyte immunoglobulin-like receptor (LILR) family members, the function of the inhibitory molecule LILRB3 (ILT5, CD85a, LIR3) remains unclear. Studies indicate a predominant myeloid expression; however, high homology within the LILR family and a relative paucity of reagents have hindered progress toward identifying the function of this receptor. To investigate its function and potential immunomodulatory capacity, a panel of LILRB3-specific monoclonal antibodies (mAbs) was generated. LILRB3-specific mAbs bound to discrete epitopes in Ig-like domain 2 or 4. LILRB3 ligation on primary human monocytes by an agonistic mAb resulted in phenotypic and functional changes, leading to potent inhibition of immune responses in vitro, including significant reduction in T cell proliferation. Importantly, agonizing LILRB3 in humanized mice induced tolerance and permitted efficient engraftment of allogeneic cells. Our findings reveal powerful immunosuppressive functions of LILRB3 and identify it as an important myeloid checkpoint receptor.

Authors

Muchaala Yeboah, Charys Papagregoriou, Des C. Jones, H.T. Claude Chan, Guangan Hu, Justine S. McPartlan, Torbjörn Schiött, Ulrika Mattson, C. Ian Mockridge, Ulla-Carin Tornberg, Björn Hambe, Anne Ljungars, Mikael Mattsson, Ivo Tews, Martin J. Glennie, Stephen M. Thirdborough, John Trowsdale, Björn Frendeus, Jianzhu Chen, Mark S. Cragg, Ali Roghanian

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Abstract

Atrial fibrillation (AF) is the most common cardiac arrhythmia, yet the molecular signature of the vulnerable atrial substrate is not well understood. Here, we delineated a distinct transcriptional signature in right versus left atrial cardiomyocytes (CMs) at baseline and identified chamber-specific gene expression changes in patients with a history of AF in the setting of end-stage heart failure (AF+HF) that are not present in heart failure alone (HF). We observed that human left atrial (LA) CMs exhibited Notch pathway activation and increased ploidy in AF+HF but not in HF alone. Transient activation of Notch signaling within adult CMs in a murine genetic model is sufficient to increase ploidy in both atrial chambers. Notch activation within LA CMs generated a transcriptomic fingerprint resembling AF, with dysregulation of transcription factor and ion channel genes, including Pitx2, Tbx5, Kcnh2, Kcnq1, and Kcnip2. Notch activation also produced distinct cellular electrophysiologic responses in LA versus right atrial CMs, prolonging the action potential duration (APD) without altering the upstroke velocity in the left atrium and reducing the maximal upstroke velocity without altering the APD in the right atrium. Our results support a shared human/murine model of increased Notch pathway activity predisposing to AF.

Authors

Catherine E. Lipovsky, Jesus Jimenez, Qiusha Guo, Gang Li, Tiankai Yin, Stephanie C. Hicks, Somya Bhatnagar, Kentaro Takahashi, David M. Zhang, Brittany D. Brumback, Uri Goldsztejn, Rangarajan D. Nadadur, Carlos Perez-Cervantez, Ivan P. Moskowitz, Shaopeng Liu, Bo Zhang, Stacey L. Rentschler

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Abstract

Tregs are crucial for maintaining maternal immunotolerance against the semiallogeneic fetus. We investigated the elusive transcriptional profile and functional adaptation of human uterine Tregs (uTregs) during pregnancy. Uterine biopsies, from placental bed (materno-fetal interface) and incision site (control) and blood were obtained from women with uncomplicated pregnancies undergoing cesarean section. Tregs and CD4+ non-Tregs were isolated for transcriptomic profiling by Cel-Seq2. Results were validated on protein and single cell levels by flow cytometry. Placental bed uTregs showed elevated expression of Treg signature markers, including FOXP3, CTLA-4, and TIGIT. Their transcriptional profile was indicative of late-stage effector Treg differentiation and chronic activation, with increased expression of immune checkpoints GITR, TNFR2, OX-40, and 4-1BB; genes associated with suppressive capacity (HAVCR2, IL10, LAYN, and PDCD1); and transcription factors MAF, PRDM1, BATF, and VDR. uTregs mirrored non-Treg Th1 polarization and tissue residency. The particular transcriptional signature of placental bed uTregs overlapped strongly with that of tumor-infiltrating Tregs and was remarkably pronounced at the placental bed compared with uterine control site. In conclusion, human uTregs acquire a differentiated effector Treg profile similar to tumor-infiltrating Tregs, specifically at the materno-fetal interface. This introduces the concept of site-specific transcriptional adaptation of Tregs within 1 organ.

Authors

Judith Wienke, Laura Brouwers, Leone M. van der Burg, Michal Mokry, Rianne C. Scholman, Peter G.J. Nikkels, Bas B. van Rijn, Femke van Wijk

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Abstract

Acute graft-versus-host disease (aGVHD) can occur after hematopoietic cell transplant in patients undergoing treatment for hematological malignancies or inborn errors. Although CD4+ T helper (Th) cells play a major role in aGVHD, the mechanisms by which they contribute, particularly within the intestines, have remained elusive. We have identified a potentially novel subset of Th cells that accumulated in the intestines and produced the serine protease granzyme A (GrA). GrA+ Th cells were distinct from other Th lineages and exhibited a noncytolytic phenotype. In vitro, GrA+ Th cells differentiated in the presence of IL-4, IL-6, and IL-21 and were transcriptionally unique from cells cultured with either IL-4 or the IL-6/IL-21 combination alone. In vivo, both STAT3 and STAT6 were required for GrA+ Th cell differentiation and played roles in maintenance of the lineage identity. Importantly, GrA+ Th cells promoted aGVHD-associated morbidity and mortality and contributed to crypt destruction within intestines but were not required for the beneficial graft-versus-leukemia effect. Our data indicate that GrA+ Th cells represent a distinct Th subset and are critical mediators of aGVHD.

Authors

Sungtae Park, Brad Griesenauer, Hua Jiang, Djamilatou Adom, Pegah Mehrpouya-Bahrami, Srishti Chakravorty, Majid Kazemian, Tanbeena Imam, Rajneesh Srivastava, Tristan A. Hayes, Julian Pardo, Sarath Chandra Janga, Sophie Paczesny, Mark H. Kaplan, Matthew R. Olson

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Abstract

Evaluation of potential immunity against the novel severe acute respiratory syndrome (SARS) coronavirus that emerged in 2019 (SARS-CoV-2) is essential for health, as well as social and economic recovery. Generation of antibody response to SARS-CoV-2 (seroconversion) may inform on acquired immunity from prior exposure, and antibodies against the SARS-CoV-2 spike protein receptor binding domain (S-RBD) are speculated to neutralize virus infection. Some serology assays rely solely on SARS-CoV-2 nucleocapsid protein (N-protein) as the antibody detection antigen; however, whether such immune responses correlate with S-RBD response and COVID-19 immunity remains unknown. Here, we generated a quantitative serological ELISA using recombinant S-RBD and N-protein for the detection of circulating antibodies in 138 serial serum samples from 30 reverse transcription PCR–confirmed, SARS-CoV-2–hospitalized patients, as well as 464 healthy and non–COVID-19 serum samples that were collected between June 2017 and June 2020. Quantitative detection of IgG antibodies against the 2 different viral proteins showed a moderate correlation. Antibodies against N-protein were detected at a rate of 3.6% in healthy and non–COVID-19 sera collected during the pandemic in 2020, whereas 1.9% of these sera were positive for S-RBD. Approximately 86% of individuals positive for S-RBD–binding antibodies exhibited neutralizing capacity, but only 74% of N-protein–positive individuals exhibited neutralizing capacity. Collectively, our studies show that detection of N-protein–binding antibodies does not always correlate with presence of S-RBD–neutralizing antibodies and caution against the extensive use of N-protein–based serology testing for determination of potential COVID-19 immunity.

Authors

Kathleen M. McAndrews, Dara P. Dowlatshahi, Jianli Dai, Lisa M. Becker, Janine Hensel, Laura M. Snowden, Jennifer M. Leveille, Michael R. Brunner, Kylie W. Holden, Nikolas S. Hopkins, Alexandria M. Harris, Jerusha Kumpati, Michael A. Whitt, J. Jack Lee, Luis L. Ostrosky-Zeichner, Ramesha Papanna, Valerie S. LeBleu, James P. Allison, Raghu Kalluri

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Abstract

Tumor-associated macrophages (TAMs) affect cancer progression and therapy. Ovarian carcinoma often metastasizes to the peritoneal cavity. Here, we found 2 peritoneal macrophage subsets in mice bearing ID8 ovarian cancer based on T cell immunoglobulin and mucin domain containing 4 (Tim-4) expression. Tim-4+ TAMs were embryonically originated and locally sustained while Tim-4– TAMs were replenished from circulating monocytes. Tim-4+ TAMs, but not Tim-4– TAMs, promoted tumor growth in vivo. Relative to Tim-4– TAMs, Tim-4+ TAMs manifested high oxidative phosphorylation and adapted mitophagy to alleviate oxidative stress. High levels of arginase-1 in Tim-4+ TAMs contributed to potent mitophagy activities via weakened mTORC1 activation due to low arginine resultant from arginase-1–mediated metabolism. Furthermore, genetic deficiency of autophagy element FAK family-interacting protein of 200 kDa resulted in Tim-4+ TAM loss via ROS-mediated apoptosis and elevated T cell immunity and ID8 tumor inhibition in vivo. Moreover, human ovarian cancer–associated macrophages positive for complement receptor of the immunoglobulin superfamily (CRIg) were transcriptionally, metabolically, and functionally similar to murine Tim-4+ TAMs. Thus, targeting CRIg+ (Tim-4+) TAMs may potentially treat patients with ovarian cancer with peritoneal metastasis.

Authors

Houjun Xia, Shasha Li, Xiong Li, Weichao Wang, Yingjie Bian, Shuang Wei, Sara Grove, Weimin Wang, Linda Vatan, J. Rebecca Liu, Karen McLean, Ramandeep Rattan, Adnan Munkarah, Jun-Lin Guan, Ilona Kryczek, Weiping Zou

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Abstract

Age-associated systemic, chronic inflammation is partially attributed to increased self-autoreactivity, resulting from disruption of central tolerance in the aged, involuted thymus. This involution causally results from gradually decreased expression of the transcription factor FOXN1 in thymic epithelial cells (TECs), whereas exogenous FOXN1 in TECs can partially rescue age-related thymic involution. TECs induced from FOXN1-overexpressing embryonic fibroblasts can generate an ectopic de novo thymus under the kidney capsule, and intrathymic injection of naturally young TECs can lead to middle-aged thymus regrowth. Therefore, as a thymic rejuvenation strategy, we extended these 2 findings by combining them with 2 types of promoter-driven (Rosa26CreERT and FoxN1Cre) Cre-mediated FOXN1-reprogrammed embryonic fibroblasts (FREFs). We engrafted these FREFs directly into the aged murine thymus. We found substantial regrowth of the native aged thymus with rejuvenated architecture and function in both males and females, exhibiting increased thymopoiesis and reinforced thymocyte negative selection, along with reduced senescent T cells and autoreactive T cell–mediated inflammation in old mice. Therefore, this approach has preclinical significance and presents a strategy to potentially rescue decreased thymopoiesis and perturbed negative selection to substantially, albeit partially, restore defective central tolerance and reduce subclinical autoimmune symptoms in elderly people.

Authors

Jiyoung Oh, Weikan Wang, Rachel Thomas, Dong-Ming Su

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Abstract

BACKGROUND Control of the tuberculosis (TB) pandemic remains hindered in part by a lack of simple and accurate measures of treatment efficacy, as current gold standard markers rely on sputum-based assays that are slow and challenging to implement. However, previous work identified urinary N1, N12-diacetylspermine (DiAcSpm), neopterin, hydroxykynurenine, N-acetylhexosamine, ureidopropionic acid, sialic acid, and mass-to-charge ratio (m/z) 241.0903 as potential biomarkers of active pulmonary TB (ATB). Here, we evaluated their ability to serve as biomarkers of TB treatment response and mycobacterial load.METHODS We analyzed urine samples prospectively collected from 2 cohorts with ATB. A total of 34 study participants from African countries treated with first-line TB therapy rifampin, isoniazid, pyrazinamide, and ethambutol (HRZE) were followed for 1 year, and 35 participants from Haiti treated with either HRZE or an experimental drug were followed for 14 days. Blinded samples were analyzed by untargeted HPLC-coupled high-resolution TOF-mass spectrometry.RESULTS Urinary levels of all 7 molecules significantly decreased by week 26 of successful treatment (P = 0.01 to P < 0.0001) and positively correlated with sputum mycobacterial load (P < 0.0001). Urinary DiAcSpm levels decreased significantly in participants treated with HRZE as early as 14 days (P < 0.0001) but remained unchanged in cases of ineffective therapy (P = 0.14).CONCLUSION Urinary DiAcSpm, neopterin, hydroxykynurenine, N-acetylhexosamine, ureidopropionic acid, sialic acid, and m/z 241.0903 reductions correlated with successful anti-TB treatment and sputum mycobacterial load. Urinary DiAcSpm levels exhibited reductions capable of differentiating treatment success from failure as early as 2 weeks after the initiation of chemotherapy, advocating its further development as a potentially simple, noninvasive biomarker for assessing treatment response and bacterial load.FUNDING This work was supported by the Clinical and Translational Science Center at Weill Cornell College of Medicine (NIH/NCATS 1 UL1 TR002384-02 and KL2TR000458), the Department of Defense (PR170782), the National Institute of Allergy and Infectious Disease grants (NIAID T32AI007613-16, K24 AI098627, and K23 AI131913), the NIH Fogarty International Center grants (R24 TW007988 and TW010062), NIH grant (R01 GM135926), the Abby and Howard P. Milstein Program in Chemical Biology and Translational Medicine, and the Tuberculosis Research Units Networks (TBRU-N, AI111143).

Authors

Qianjing Xia, Myung Hee Lee, Kathleen F. Walsh, Kathrine McAulay, James M. Bean, Daniel W. Fitzgerald, Kathryn M. Dupnik, Warren D. Johnson, Jean W. Pape, Kyu Y. Rhee, Flonza Isa

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Abstract

Compromised muscle mitochondrial metabolism is a hallmark of peripheral arterial disease, especially in patients with the most severe clinical manifestation — critical limb ischemia (CLI). We asked whether inflexibility in metabolism is critical for the development of myopathy in ischemic limb muscles. Using Polg mtDNA mutator (D257A) mice, we reveal remarkable protection from hind limb ischemia (HLI) due to a unique and beneficial adaptive enhancement of glycolytic metabolism and elevated ischemic muscle PFKFB3. Similar to the relationship between mitochondria from CLI and claudicating patient muscles, BALB/c muscle mitochondria are uniquely dysfunctional after HLI onset as compared with the C57BL/6 (BL6) parental strain. AAV-mediated overexpression of PFKFB3 in BALB/c limb muscles improved muscle contractile function and limb blood flow following HLI. Enrichment analysis of RNA sequencing data on muscle from CLI patients revealed a unique deficit in the glucose metabolism Reactome. Muscles from these patients express lower PFKFB3 protein, and their muscle progenitor cells possess decreased glycolytic flux capacity in vitro. Here, we show supplementary glycolytic flux as sufficient to protect against ischemic myopathy in instances where reduced blood flow–related mitochondrial function is compromised preclinically. Additionally, our data reveal reduced glycolytic flux as a common characteristic of the failing CLI patient limb skeletal muscle.

Authors

Terence E. Ryan, Cameron A. Schmidt, Michael D. Tarpey, Adam J. Amorese, Dean J. Yamaguchi, Emma J. Goldberg, Melissa M.R. Iñigo, Reema Karnekar, Allison O’Rourke, James M. Ervasti, Patricia Brophy, Thomas D. Green, P. Darrell Neufer, Kelsey Fisher-Wellman, Espen E. Spangenburg, Joseph M. McClung

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Abstract

Angiogenesis is essential for cardiac functional recovery after myocardial infarction (MI). HSPA12B is predominately expressed in endothelial cells and required for angiogenesis. Yes-associated protein (YAP) plays an important role in tumor angiogenesis. This study investigated the cooperative role of HSPA12B and YAP in angiogenesis after MI. Silencing of either HSPA12B or YAP impaired hypoxia-promoted endothelial cell proliferation and angiogenesis. Deficiency of HSPA12B suppressed YAP expression and nuclear translocation after hypoxia. Knockdown of YAP attenuated hypoxia-stimulated HSPA12B nuclear translocation and abrogated HSPA12B-promoted endothelial cell angiogenesis. Mechanistically, hypoxia induced an interaction between endothelial HSPA12B and YAP. ChIP assay showed that HSPA12B is a target gene of YAP/transcriptional enhanced associated domain 4 (TEAD4) and a coactivator in YAP-associated angiogenesis. In vivo studies using the MI model showed that endothelial cell–specific deficiency of HSPA12B (eHspa12b–/–) or YAP (eYap–/–) impaired angiogenesis and exacerbated cardiac dysfunction compared with WT mice. MI increased YAP expression and nuclear translocation in WT hearts but not eHspa12b–/– hearts. HSPA12B expression and nuclear translocation were upregulated in WT MI hearts but not eYap–/– MI myocardium. Our data demonstrate that endothelial HSPA12B is a target and coactivator for YAP/TEAD4 and cooperates with YAP to regulate endothelial angiogenesis after MI.

Authors

Min Fan, Kun Yang, Xiaohui Wang, Yana Wang, Fei Tu, Tuanzhu Ha, Li Liu, David L. Williams, Chuanfu Li

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Abstract

African green monkeys (AGMs) are natural hosts of SIV that postthymically downregulate CD4 to maintain a large population of CD4–CD8aa+ virus-resistant cells with Th functionality, which can result in AGMs becoming apparently cured of SIVagm infection. To understand the mechanisms of this process, we performed genome-wide transcriptional analysis on T cells induced to downregulate CD4 in vitro from AGMs and closely related patas monkeys and T cells that maintain CD4 expression from rhesus macaques. In T cells that downregulated CD4, pathway analysis revealed an atypical regulation of the DNA methylation machinery, which was reversible when pharmacologically targeted with 5-aza-2 deoxycytidine. This signature was driven largely by the dioxygenase TET3, which became downregulated with loss of CD4 expression. CpG motifs within the AGM CD4 promoter region became methylated during CD4 downregulation in vitro and were stably imprinted in AGM CD4–CD8aa+ T cells sorted directly ex vivo. These results suggest that AGMs use epigenetic mechanisms to durably silence the CD4 gene. Manipulation of these mechanisms could provide avenues for modulating SIV and HIV-1 entry receptor expression in hosts that become progressively infected with SIV, which could lead to novel therapeutic interventions aimed to reduce HIV viremia in vivo.

Authors

Joseph C. Mudd, Stephen Lai, Sanjana Shah, Andrew Rahmberg, Jacob K. Flynn, Carly E. Starke, Molly R. Perkins, Amy Ransier, Sam Darko, Daniel C. Douek, Vanessa M. Hirsch, Mark Cameron, Jason M. Brenchley

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Abstract

Establishing the interactome of the cancer-associated stress protein Nuclear Protein 1 (NUPR1), we found that it binds to several hundreds of proteins, including proteins involved in nuclear translocation, DNA repair, and key factors of the SUMO pathway. We demonstrated that the NUPR1 inhibitor ZZW-115, an organic synthetic molecule, competes with importins for the binding to the NLS region of NUPR1, thereby inhibiting its nuclear translocation. We hypothesized, and then proved, that inhibition of NUPR1 by ZZW-115 sensitizes cancer cells to DNA damage induced by several genotoxic agents. Strikingly, we found that treatment with ZZW-115 reduced SUMOylation of several proteins involved in DNA damage response (DDR). We further report that the presence of recombinant NUPR1 improved the SUMOylation in a cell-free system, indicating that NUPR1 directly stimulates the SUMOylation machinery. We propose that ZZW-115 sensitizes cancer cells to genotoxic agents by inhibiting the nuclear translocation of NUPR1 and thereby decreasing the SUMOylation-dependent functions of key proteins involved in the DDR.

Authors

Wenjun Lan, Patricia Santofimia-Castaño, Mirna Swayden, Yi Xia, Zhengwei Zhou, Stephane Audebert, Luc Camoin, Can Huang, Ling Peng, Ana Jiménez-Alesanco, Adrián Velázquez-Campoy, Olga Abián, Gwen Lomberk, Raul Urrutia, Bruno Rizzuti, Vincent Geli, Philippe Soubeyran, José L. Neira, Juan Iovanna

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Abstract

Based on its clinical benefits, Trikafta — the combination of folding correctors VX-661 (tezacaftor), VX-445 (elexacaftor), and the gating potentiator VX-770 (ivacaftor) — was FDA approved for treatment of patients with cystic fibrosis (CF) carrying deletion of phenylalanine at position 508 (F508del) of the CF transmembrane conductance regulator (CFTR) on at least 1 allele. Neither the mechanism of action of VX-445 nor the susceptibility of rare CF folding mutants to Trikafta are known. Here, we show that, in human bronchial epithelial cells, VX-445 synergistically restores F508del-CFTR processing in combination with type I or II correctors that target the nucleotide binding domain 1 (NBD1) membrane spanning domains (MSDs) interface and NBD2, respectively, consistent with a type III corrector mechanism. This inference was supported by the VX-445 binding to and unfolding suppression of the isolated F508del-NBD1 of CFTR. The VX-661 plus VX-445 treatment restored F508del-CFTR chloride channel function in the presence of VX-770 to approximately 62% of WT CFTR in homozygous nasal epithelia. Substantial rescue of rare misprocessing mutations (S13F, R31C, G85E, E92K, V520F, M1101K, and N1303K), confined to MSD1, MSD2, NBD1, and NBD2 of CFTR, was also observed in airway epithelia, suggesting an allosteric correction mechanism and the possible application of Trikafta for patients with rare misfolding mutants of CFTR.

Authors

Guido Veit, Ariel Roldan, Mark A. Hancock, Dillon F. Da Fonte, Haijin Xu, Maytham Hussein, Saul Frenkiel, Elias Matouk, Tony Velkov, Gergely L. Lukacs

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Abstract

ETV6 is an ETS family transcription factor that plays a key role in hematopoiesis and megakaryocyte development. Our group and others have identified germline mutations in ETV6 resulting in autosomal dominant thrombocytopenia and predisposition to malignancy; however, molecular mechanisms defining the role of ETV6 in megakaryocyte development have not been well established. Using a combination of molecular, biochemical, and sequencing approaches in patient-derived PBMCs, we demonstrate abnormal cytoplasmic localization of ETV6 and the HDAC3/NCOR2 repressor complex that led to overexpression of HDAC3-regulated interferon response genes. This transcriptional dysregulation was also reflected in patient-derived platelet transcripts and drove aberrant proplatelet formation in megakaryocytes. Our results suggest that aberrant transcription may predispose patients with ETV6 mutations to bone marrow inflammation, dysplasia, and megakaryocyte dysfunction.

Authors

Marlie H. Fisher, Gregory D. Kirkpatrick, Brett Stevens, Courtney Jones, Michael Callaghan, Madhvi Rajpurkar, Joy Fulbright, Megan A. Cooper, Jesse Rowley, Christopher C. Porter, Arthur Gutierrez-Hartmann, Kenneth Jones, Craig Jordan, Eric M. Pietras, Jorge Di Paola

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Abstract

Arrhythmogenic cardiomyopathy (AC) is a heart disease often caused by mutations in genes coding for desmosomal proteins, including desmoglein-2 (DSG2), plakoglobin (PG), and desmoplakin (DP). Therapy is based on symptoms and limiting arrhythmia, because the mechanisms by which desmosomal components control cardiomyocyte function are largely unknown. A new paradigm could be to stabilize desmosomal cardiomyocyte adhesion and hyperadhesion, which renders desmosomal adhesion independent from Ca2+. Here, we further characterized the mechanisms behind enhanced cardiomyocyte adhesion and hyperadhesion. Dissociation assays performed in HL-1 cells and murine ventricular cardiac slice cultures allowed us to define a set of signaling pathways regulating cardiomyocyte adhesion under basal and hyperadhesive conditions. Adrenergic signaling, activation of PKC, and inhibition of p38MAPK enhanced cardiomyocyte adhesion, referred to as positive adhesiotropy, and induced hyperadhesion. Activation of ERK1/2 paralleled positive adhesiotropy, whereas adrenergic signaling induced PG phosphorylation at S665 under both basal and hyperadhesive conditions. Adrenergic signaling and p38MAPK inhibition recruited DSG2 to cell junctions. In PG-deficient mice with an AC phenotype, only PKC activation and p38MAPK inhibition enhanced cardiomyocyte adhesion. Our results demonstrate that cardiomyocyte adhesion can be stabilized by different signaling mechanisms, which are in part offset in PG-deficient AC.

Authors

Maria Shoykhet, Sebastian Trenz, Ellen Kempf, Tatjana Williams, Brenda Gerull, Camilla Schinner, Sunil Yeruva, Jens Waschke

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Abstract

Lynch syndrome is the most common cause of hereditary colorectal cancer (CRC), and it is characterized by DNA mismatch repair (MMR) deficiency. The term Lynch-like syndrome (LLS) is used for patients with MMR-deficient tumors and neither germline mutation in MLH1, MSH2, MSH6, PMS2, or EPCAM nor MLH1 somatic methylation. Biallelic somatic inactivation or cryptic germline MMR variants undetected during genetic testing have been proposed to be involved. Sixteen patients with early-onset LLS CRC were selected for germline and tumor whole-exome sequencing. Two potentially pathogenic germline MCM8 variants were detected in a male patient with LLS with fertility problems. A knockout cellular model for MCM8 was generated by CRISPR/Cas9 and detected genetic variants were produced by mutagenesis. DNA damage, microsatellite instability, and mutational signatures were monitored. DNA damage was evident for MCM8KO cells and the analyzed genetic variants. Microsatellite instability and mutational signatures in MCM8KO cells were compatible with the involvement of MCM8 in MMR. Replication in an independent familial cancer cohort detected additional carriers. Unexplained MMR-deficient CRC cases, even showing somatic biallelic MMR inactivation, may be caused by underlying germline defects in genes different than MMR genes. We suggest MCM8 as a gene involved in CRC germline predisposition with a recessive pattern of inheritance.

Authors

Mariano Golubicki, Laia Bonjoch, José G. Acuña-Ochoa, Marcos Díaz-Gay, Jenifer Muñoz, Miriam Cuatrecasas, Teresa Ocaña, Soledad Iseas, Guillermo Mendez, Daniel Cisterna, Stephanie A. Schubert, Maartje Nielsen, Tom van Wezel, Yael Goldberg, Eli Pikarsky, Juan Robbio, Enrique Roca, Antoni Castells, Francesc Balaguer, Marina Antelo, Sergi Castellví-Bel

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Abstract

We determined that renal proximal tubular (PT) NFκB essential modulator (NEMO) plays a direct and critical role in ischemic acute kidney injury (AKI) utilizing using mice lacking renal PT NEMO and by targeted renal PT NEMO inhibition with mesoscale nanoparticle encapsulated NEMO binding peptide (MNP NBP). We subjected renal PT NEMO deficient mice, wild type (WT) mice and C57BL/6 mice to sham surgery or 30 min renal ischemia and reperfusion (IR). C57BL/6 mice received NBP MNP or empty MNP before renal IR injury. Mice treated with MNP NBP and mice deficient in renal PT NEMO were protected against ischemic AKI with decreased renal tubular necrosis, inflammation and apoptosis compared to control MNP treated or WT mice, respectively. Recombinant peptidylarginine deiminase type-4 (rPAD4) targets kidney PT NEMO to exacerbate ischemic AKI as exogenous rPAD4 exacerbated renal IR injury in WT mice but not in renal proximal tubule NEMO deficient mice. Furthermore, rPAD4 upregulated proinflammatory cytokine mRNA and NFκB activation in freshly isolated renal proximal tubules from WT mice but not from PT NEMO deficient mice. Taken together, our studies suggest that renal PT NEMO plays a critical role in ischemic AKI by promoting renal tubular inflammation, apoptosis as well as necrosis.

Authors

Sang Jun Han, Ryan M. williams, Mihwa Kim, Daniel A. Heller, Vivette D'Agati, Marc Schmidt-Supprian, H. Thomas Lee

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Abstract

Fibrosis is the final common pathway in the pathophysiology of most forms of chronic kidney disease (CKD). As treatment of renal fibrosis still remains largely supportive, a refined understanding of the cellular and molecular mechanisms of kidney fibrosis and the development of novel compounds are urgently needed. Whether arginases play a role in development of fibrosis in CKD is unclear. We hypothesize that endothelial-arginase-2 (Arg2) promotes the development of kidney fibrosis induced by unilateral ureteral obstruction (UUO). Arg2 expression and arginase activity significantly increased following renal fibrosis. Pharmacological blockade or genetic deficiency of Arg2 conferred kidney protection following renal fibrosis as reflected by a reduction in kidney interstitial fibrosis and fibrotic markers. Selective deletion of Arg2 in endothelial cells (Tie2Cre/Arg2flox/flox) reduced the level of fibrosis after UUO. In contrast, selective deletion of Arg2 specifically in proximal tubular cells (Ggt1Cre/Arg2flox/flox) failed to reduce renal fibrosis after UUO. Furthermore, arginase inhibition restored kidney nitric oxide (NO) levels, oxidative stress, and mitochondrial function following UUO.These findings indicate that endothelial-Arg2 plays a major role in renal fibrosis via its action on NO and mitochondrial function. Blocking Arg2 activity or expression could be a novel therapeutic approach for prevention of CKD.

Authors

Michael Wetzel, Kristen Stanley, Wei Wei Wang, Soumya Maity, Muniswamy Madesh, W. Brian Reeves, Alaa S. Awad

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Abstract

Pre-existing humoral immunity to recombinant adeno-associated viral (AAV) vectors restricts the treatable patient population and efficacy of human gene therapies. Approaches to clear neutralizing antibodies (NAbs), such as plasmapheresis and immunosuppression are either ineffective or cause undesirable side effects. Here, we describe a clinically relevant strategy to rapidly and transiently degrade NAbs prior to AAV administration using an IgG degrading enzyme (IdeZ). We demonstrate that recombinant IdeZ efficiently cleaves IgG in dog, monkey and human antisera. Prophylactically administered IdeZ cleaves circulating, human IgG in mice and prevents AAV neutralization in vivo. In macaques, a single intravenous dose of IdeZ rescues AAV transduction by transiently reversing seropositivity. Importantly, IdeZ efficiently cleaves NAbs and rescues AAV transduction in mice passively immunized with individual human donor sera representing a diverse population. Our antibody clearance approach presents a new paradigm for expanding the prospective patient cohort and improving efficacy of AAV gene therapy.

Authors

Zachary C. Elmore, Daniel K. Oh, Katherine E. Simon, Marco M. Fanous, Aravind Asokan

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Abstract

Background: Physical frailty in older individuals is characterized by subjective symptoms of fatigue and exercise intolerance (EI). Objective abnormalities in skeletal muscle (SM) mitochondrial high-energy phosphate (HEP) metabolism contribute to EI in inherited myopathies, but their presence or link to EI in the frail older adult is unknown. Methods: Three groups of ambulatory, community-dwelling adults with no history of significant coronary disease were studied: frail, older individuals (FO, 81±2.7 years, mean±SEM), non-frail, older individuals (NFO, 79±2.0 years), and healthy middle-aged controls (CONT, 51±2.1 years). Lower extremity SM HEP levels and mitochondrial function were measured with 31P magnetic resonance (MR) techniques during graded, multistage plantar flexion exercise (PFE). EI was quantified by six-minute walk and peak oxygen consumption during cardiopulmonary testing (peak-VO2). Results: During graded exercise, frail older (FO), non-frail older (NFO), and healthy middle-aged individuals all fatigued at similar SM HEP levels measured by 31P MR. However, FO fatigued fastest with several-fold higher rates of PFE-induced HEP decline, which correlated closely with shorter exercise duration in the MR scanner and with six-minute walk distance and lower peak oxygen consumption on cardiopulmonary testing (p<0.001 for all). SM mitochondrial oxidative capacity was lower in older individuals and correlated with rapid HEP decline but less closely with EI. Conclusions: Several-fold faster skeletal muscle energetic decline during exercise occurs in frail older individuals and correlates closely with multiple measures of EI. Rapid energetic decline represents an objective, functional measure of SM metabolic changes and a potential new target for mitigating frailty-associated physical limitations.

Authors

Sabra C. Lewsey, Kilian Weiss, Michael Schär, Yi Zhang, Paul A. Bottomley, T. Jake Samuel, Qian-Li Xue, Angela Steinberg, Jeremy Walston, Gary Gerstenblith, Robert G. Weiss

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Abstract

Background: Patients infected with SARS-CoV-2 differ in the severity of disease. We hypothesized that characteristics of SARS-CoV-2 specific immunity correlate with disease severity. Methods: In this study, SARS-CoV-2 specific T-cells and antibodies were characterized in uninfected controls and patients with different COVID-19 related disease severity. SARS-CoV-2 specific T-cells were flow-cytometrically quantified after stimulation with SARS-CoV-2 peptide pools and analyzed for expression of cytokines (IFNγ, IL-2 and TNFα) and markers for activation, proliferation and functional anergy. SARS-CoV-2 specific IgG and IgA antibodies were quantified using ELISA. Moreover, global characteristics of lymphocyte subpopulations were compared between patient groups and uninfected controls Results: Despite severe lymphopenia affecting all major lymphocyte subpopulations, patients with severe disease mounted significantly higher levels of SARS-CoV-2 specific T-cells as compared to convalescent individuals. SARS-CoV-2 specific CD4 T-cells dominated over CD8 T-cells and closely correlated with the number of plasmablasts and SARS-CoV-2 specific IgA- and IgG-levels. Unlike in convalescents, SARS-CoV-2 specific T-cells in patients with severe disease showed marked alterations in phenotypical and functional properties, which also extended to CD4 and CD8 T-cells in general. Conclusion: Given the strong induction of specific immunity to control viral replication in patients with severe disease, the functionally altered characteristics may result from the need for contraction of specific and general immunity to counteract excessive immunopathology in the lung. Trial registration: n.a. Funding: The study was supported by institutional funds by M.S., and in part by grants of Saarland University (to M.S. and. R.B), the State of Saarland, and the Dr. Rolf M. Schwiete Stiftung to R.B.

Authors

David Schub, Verena Klemis, Sophie Schneitler, Janine Mihm, Philipp M. Lepper, Heinrike Wilkens, Robert Bals, Hermann Eichler, Barbara C. Gärtner, Sören L. Becker, Urban Sester, Martina Sester, Tina Schmidt

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