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The β3-adrenergic receptor agonist mirabegron improves glucose homeostasis in obese humans

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Abstract

BACKGROUND. Beige adipose tissue is associated with improved glucose homeostasis in mice. Adipose tissue contains β3 adrenergic receptors (β3-AR), and this study was intended to determine whether the treatment of obese, insulin-resistant humans with the β3AR agonist mirabegron, which stimulates beige adipose formation in subcutaneous white adipose tissue (SC WAT), would induce other beneficial changes in fat and muscle, and improve metabolic homeostasis. METHODS. Before and after β3AR agonist treatment, oral glucose tolerance tests and euglycemic clamps were performed, and histochemistry and gene expression profiling were performed from fat and muscle biopsies. PET CT scans quantified brown adipose tissue volume and activity and we conducted in vitro studies with primary cultures of differentiated human adipocytes and muscle.RESULTS. Clinical effects of mirabegron treatment included improved oral glucose tolerance (P<0.01), reduced hemoglobin A1c (P=0.01), and improved insulin sensitivity (P=0.03) and β-cell function (P=0.01). In SC WAT, mirabegron treatment stimulated lipolysis, reduced fibrotic gene expression and increased alternatively activated macrophages. Subjects with the most SC WAT beiging demonstrated the most improvement in β-cell function. In skeletal muscle, mirabegron reduced triglycerides, increased expression of PGC1A (P<0.05), and increased type I fibers (P<0.01). Conditioned media from adipocytes treated with mirabegron stimulated muscle fiber PGC1A expression in vitro (P<0.001). CONCLUSION. Mirabegron treatment significantly improves glucose tolerance in obese, insulin resistant humans. Since β-cells and skeletal muscle do not express β3-ARs, these data suggest that the beiging of SC WAT by mirabegron reduces adipose tissue dysfunction, which enhances muscle oxidative capacity and improves β-cell function. TRIAL REGISTRATION. Clinicaltrials.gov NCT02919176.FUNDING. NIH (DK112282, P30GM127211, DK 71349, and CTSA grant UL1TR001998).

Authors

Brian S. Finlin, Hasiyet Memetimin, Beibei Zhu, Amy L. Confides, Hemendra J. Vekaria, Riham H. El Khouli, Zachary R. Johnson, Philip M. Westgate, Jianzhong Chen, Andrew J. Morris, Patrick G. Sullivan, Esther E. Dupont-Versteegden, Philip A. Kern

Cystic fibrosis transmembrane conductance regulator dysfunction in platelets drives lung hyperinflammation

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Abstract

Cystic fibrosis (CF) lung disease is characterized by an inflammatory response that can lead to terminal respiratory failure. The cystic fibrosis transmembrane regulator (CFTR) is mutated in CF and we hypothesized that dysfunctional CFTR in platelets, which are key participants in immune responses, is a central determinant of CF inflammation. We found that deletion of CFTR in platelets produced exaggerated acute lung inflammation and platelet activation after intratracheal LPS or Pseudomonas aeruginosa challenge. CFTR loss of function in mouse or human platelets resulted in agonist-induced hyperactivation and increased calcium entry into platelets. Inhibition of the transient receptor potential cation channel 6 (TRPC6) reduced platelet activation and calcium flux, and reduced lung injury in CF mice after intratracheal LPS or Pseudomonas aeruginosa challenge. CF subjects receiving CFTR modulator therapy showed partial restoration of CFTR function in platelets, which may be a convenient approach to monitoring biological responses to CFTR modulators. We conclude that CFTR dysfunction in platelets produces aberrant TRPC6-dependent platelet activation, which is a major driver of CF lung inflammation and impaired bacterial clearance. Platelets, and TRPC6, are what we believe to be novel therapeutic targets in the treatment of CF lung disease.

Authors

Guadalupe Ortiz-Munoz, Michelle A. Yu, Emma Lefrançais, Benat Mallavia, Colin Valet, Jennifer J. Tian, Serena Ranucci, Kristin M. Wang, Zhe Liu, Nicholas Kwaan, Diana Dawson, Mary Ellen Kleinhenz, Fadi T. Khasawneh, Peter M. Haggie, Alan S. Verkman, Mark R. Looney

Chronic mirabegron treatment increases human brown fat, HDL cholesterol, and insulin sensitivity

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Abstract

BACKGROUND. Mirabegron is a β3-adrenergic receptor (β3-AR) agonist approved only for the treatment of overactive bladder. Encouraging preclinical results suggest that β3-AR agonists could also improve obesity-related metabolic disease by increasing brown adipose tissue (BAT) thermogenesis, white adipose tissue (WAT) lipolysis, and insulin sensitivity. METHODS. We treated 14 healthy women of diverse ethnicity, 27.5 ± 1.1 y, BMI 25.4 ± 1.2 kg/m2, with 100 mg mirabegron (Myrbetriq extended-release tablet, Astellas Pharma) for four weeks, open-label. The primary endpoint was the change in BAT metabolic activity as measured by [18F]-2-fluoro-D-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT). Secondary endpoints included resting energy expenditure (REE), plasma metabolites, and glucose and insulin metabolism as assessed by frequently sampled intravenous glucose tolerance test. RESULTS. Chronic mirabegron therapy increased BAT metabolic activity. Whole-body REE was higher, without changes in body weight or composition. Additionally, there were elevations in plasma levels of the beneficial lipoprotein biomarkers high-density lipoprotein (HDL) and ApoA1, as well as total bile acids. Adiponectin, a WAT-derived hormone that has anti-diabetic and anti-inflammatory capabilities, increased with acute treatment and was 35% higher at study completion. Finally, an intravenous glucose tolerance test demonstrated higher insulin sensitivity, glucose effectiveness, and insulin secretion. CONCLUSION. These findings indicate that human BAT metabolic activity can be increased after chronic pharmacological stimulation with mirabegron and support the investigation of β3-AR agonists as a treatment for metabolic disease. TRIAL REGISTRATION. Clinicaltrials.gov NCT03049462. FUNDING. This work was supported by the Intramural Research Program of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), DK075112, DK075116, DK071013, and DK071014.

Authors

Alana E. O'Mara, James W. Johnson, Joyce D. Linderman, Robert J. Brychta, Suzanne McGehee, Laura A. Fletcher, Yael A. Fink, Devika Kapuria, Thomas M. Cassimatis, Nathan Kelsey, Cheryl Cero, Zahraa Abdul-Sater, Francesca Piccinini, Alison S. Baskin, Brooks P. Leitner, Hongyi Cai, Corina M. Millo, William Dieckmann, Mary Walter, Norman B. Javitt, Yaron Rotman, Peter J. Walter, Marilyn Ader, Richard N. Bergman, Peter Herscovitch, Kong Y. Chen, Aaron M. Cypess

Gut epithelial TSC1/mTOR controls RIPK3-dependent necroptosis in intestinal inflammation and cancer

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Abstract

While the Western-diet and dysbiosis are the most prominent environmental factors associated with inflammatory bowel diseases (IBDs), the corresponding host factors and cellular mechanisms remain poorly defined. Here we report that the TSC1-mTOR pathway in the gut epithelium represents a metabolic and innate immune checkpoint for intestinal dysfunction and inflammation. mTOR hyperactivation triggered by the Western-diet or Tsc1-ablation led to epithelium necroptosis, barrier disruption, and predisposition to DSS (dextran sulfate sodium)-induced colitis and inflammation-associated colon cancer. Mechanistically, our results uncovered a critical role for TSC1-mTOR in restraining the expression and activation of RIPK3 in the gut epithelium through Trim11-mediated ubiquitination and autophagy-dependent degradation. Notably, microbiota-depletion by antibiotics or gnotobiotics attenuated RIPK3 expression and activation, thereby alleviating epithelial necroptosis and colitis driven by mTOR hyperactivation. mTOR primarily impinged on RIPK3 to potentiate TNF- and microbial PAMP-induced necroptosis, and hyperactive mTOR and aberrant necroptosis were intertwined in human IBDs. Together, our data reveal a previously unsuspected link between the Western-diet, microbiota and necroptosis, and identify the mTOR-RIPK3-necroptosis axis as a driving force for intestinal inflammation and cancer.

Authors

Yadong Xie, Yifan Zhao, Lei Shi, Wei Li, Kun Chen, Min Li, Xia Chen, Haiwei Zhang, Tiantian Li, Matsuzawa-Ishimoto Yu, Xiaomin Yao, Dianhui Shao, Zunfu Ke, Jian Li, Yan Chen, Xiaoming Zhang, Jun Cui, Shuzhong Cui, Qibin Leng, Ken Cadwell, Xiaoxia Li, Hong Wei, Haibing Zhang, Huabin Li, Hui Xiao

Profilin1 delivery tunes cytoskeleton dynamics towards CNS axon regeneration

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Abstract

After trauma, regeneration of adult CNS axons is abortive causing devastating neurologic deficits. Despite progress in rehabilitative care, there is no effective treatment stimulating axon growth following injury. Using models with different regenerative capacities, followed by gain- and loss-of-function analysis, we identified profilin1 (Pfn1) as a coordinator of actin and microtubules (MTs), powering axon growth and regeneration. In growth cones, Pfn1 increased actin retrograde flow, MT growth speed and invasion of filopodia by MTs, orchestrating cytoskeleton dynamics towards axon growth. In vitro, active Pfn1 promoted MT growth in a formin-dependent manner, whereas localization of MTs to growth cone filopodia was facilitated by direct MT binding and interaction with formins. In vivo, Pfn1 ablation limited regeneration of growth-competent axons after sciatic nerve and spinal cord injury. Adeno-associated viral (AAV) delivery of constitutively active Pfn1 to rodents promoted axon regeneration, neuromuscular junction maturation and functional recovery of injured sciatic nerves, and increased the ability of regenerating axons to penetrate the inhibitory spinal cord glial scar. Thus, we identify Pfn1 as an important regulator of axon regeneration and suggest that AAV-mediated delivery of constitutively active Pfn1, together with the identification of modulators of Pfn1 activity, should be considered to treat the injured nervous system.

Authors

Rita Pinto-Costa, Sara Castro Sousa, Sérgio C. Leite, Joana Nogueira-Rodrigues, Tiago Ferreira da Silva, Diana Machado, Joana Beatriz Moreira Marques, Ana Catarina Costa, Márcia A. Liz, Francesca Bartolini, Pedro Brites, Mercedes Costell, Reinhard Fässler, Monica M. Sousa

Epithelial splicing regulatory protein 2-mediated alternative splicing reprograms hepatocytes in severe alcoholic hepatitis

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Abstract

Severe alcoholic hepatitis (SAH) is a deadly liver disease without an effective medical therapy. Although SAH mortality is known to correlate with hepatic accumulation of immature liver cells, why this occurs, and how it causes death is unclear. Here, we demonstrated that expression of epithelial splicing regulatory protein-2 (ESRP2), an RNA splicing factor that maintains the non-proliferative, mature phenotype of adult hepatocytes, was suppressed in both human SAH and various mouse models of SAH in parallel with the severity of alcohol consumption and liver damage. Inflammatory cytokines released by excessive alcohol ingestion reprogrammed adult hepatocytes into proliferative, fetal-like cells by suppressing ESRP2. Sustained loss of ESRP2 permitted re-emergence of a fetal RNA splicing program that attenuates the Hippo signaling pathway and thus, allows fetal transcriptional regulators to accumulate in adult liver. We further showed that depleting ESRP2 in mice exacerbated alcohol-induced steatohepatitis, enabling surviving hepatocytes to shed adult hepatocyte functions and become more regenerative but threatens overall survival by populating the liver with functionally-immature hepatocytes. Our findings revealed a novel mechanism that explains why liver failure develops in patients with the clinical syndrome of SAH, suggesting that recovery from SAH might be improved by limiting adult-to-fetal reprogramming in hepatocytes.

Authors

Jeongeun Hyun, Zhaoli Sun, Ali Reza Ahmadi, Sushant Bangru, Ullas V. Chembazhi, Kuo Du, Tianyi Chen, Hidekazu Tsukamoto, Ivan Rusyn, Auinash Kalsotra, Anna Mae Diehl

Live attenuated pertussis vaccine BPZE1 induces a broad antibody response in humans

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Abstract

BACKGROUND. The live attenuated BPZE1 vaccine candidate induces protection against B. pertussis and prevents nasal colonization in animal models. Here we report on the responses in humans receiving a single intranasal administration of BPZE1. METHODS. We performed multiple assays to dissect the immune responses induced in humans (n=12) receiving BPZE1, with particular emphasis on the magnitude and characteristics of the antibody responses. Such responses were benchmarked to adolescents (n=12) receiving the complete vaccination program of the currently used acellular pertussis vaccine (aPV). Using immunoproteomics analysis, novel immunogenic B. pertussis antigens were identified. RESULTS. All BPZE1 vaccinees showed robust B. pertussis-specific antibody responses with regard to significant increase in one or more of the parameters IgG, IgA and memory B cells to B. pertussis antigens. BPZE1-specific T cells showed a Th1 phenotype and the IgG exclusively consisted of IgG1 and IgG3. In contrast, all aPV vaccinees showed a Th2-biased response. Immunoproteomics profiling revealed that BPZE1 elicited broader and different antibody specificities to B. pertussis antigens as compared to the aPV that primarily induced antibodies to the vaccine antigens. Moreover, BPZE1 was superior at inducing opsonizing antibodies that stimulated reactive oxygen species (ROS) production in neutrophils and enhanced bactericidal function, which was in line with that antibodies against adenylate cyclase toxin were only elicited by BPZE1. CONCLUSIONS. The breadth of the antibodies, the Th1-type cellular response and killing mechanisms elicited by BPZE1 may hold prospects of improving vaccine efficacy and protection against B. pertussis transmission. TRIAL REGISTRATION. ClinicalTrials.gov NCT02453048, NCT00870350 FUNDING. ILiAD Biotechnologies, Swedish Research Council (Vetenskapsrådet), Swedish Heart-lung Foundation.

Authors

Ang Lin, Danijela Apostolovic, Maja Jahnmatz, Frank Liang, Sebastian Ols, Teghesti Tecleab, Chenyan Wu, Marianne van Hage, Ken Solovay, Keith Rubin, Camille Locht, Rigmor Thorstensson, Marcel Thalen, Karin Loré

Transcription factor c-Maf is a checkpoint that programs macrophages in lung cancer

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Abstract

Macrophages have been linked to tumor initiation, progression, metastasis and treatment resistance. However, the transcriptional regulation of macrophages driving the pro-tumor function remains elusive. Here, we demonstrate that the transcription factor c-Maf is a critical controller for immunosuppressive macrophage polarization and function in cancer. c-Maf controls many M2-related genes and has direct binding sites within a conservative non-coding sequence of csf-1r gene and promotes M2-like macrophage-mediated T cell suppression and tumor progression. c-Maf also serves as a metabolic checkpoint regulating TCA cycle and UDP-GlcNAc biosynthesis thus promoting M2-like macrophage polarization and activation. Additionally, c-Maf is highly expressed in tumor-associated macrophages (TAM) and regulates TAM immunosuppressive function. Deletion of c-Maf specifically in myeloid cells results in reduced tumor burden with enhanced antitumor T cell immunity. Inhibition of c-Maf partly overcomes resistance to anti-PD-1 therapy in a subcutaneous LLC tumor model. Similarly, c-Maf is expressed in human M2 and tumor-infiltrating macrophages/monocytes as well as circulating monocytes of human non-small cell lung carcinoma (NSCLC) patients and critically regulates its immunosuppressive activity. Natural compound β-glucan downregulates c-Maf expression on macrophages leading to enhanced antitumor immunity in mice. These findings establish a paradigm for immunosuppressive macrophage polarization and transcriptional regulation by c-Maf and suggest that c-Maf is a potential target for effective tumor immunotherapy.

Authors

Min Liu, Zan Tong, Chuanlin Ding, Fengling Luo, Shouzhen Wu, Caijun Wu, Sabrin Albeituni, Liqing He, Xiaoling Hu, David Tieri, Eric C. Rouchka, Michito Hamada, Satoru Takahashi, Andrew A. Gibb, Goetz Kloecker, Huang-Ge Zhang, Michael Bousamra, Bradford G. Hill, Xiang Zhang, Jun Yan

Visceral adipose NLRP3 impairs cognition in obesity via IL1R1 on Cx3cr1⁺ cells

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Abstract

Induction of the inflammasome protein cryopyrin (NLRP3) in visceral adipose tissue (VAT) promotes release of the pro-inflammatory cytokine interleukin-1β (IL1β) in obesity. While this mechanism contributes to peripheral metabolic dysfunction, effects on the brain remain unexplored. These studies investigated whether visceral adipose NLRP3 impairs cognition by activating microglial interleukin-1 receptor 1 (IL1R1). After observing protection against obesity-induced neuroinflammation and cognitive impairment in NLRP3KO mice, we transplanted VAT from obese WT or NLRP3KO donors into lean recipients. Transplantation of VAT from a WT donor (TRANSWT) increased hippocampal IL1β and impaired cognition, but VAT transplants from comparably obese NLRP3KO donors (TRANSKO) had no effect. Visceral adipose NLRP3 was required for deficits in long-term potentiation (LTP) in transplant recipients, and LTP impairment in TRANSWT mice was IL1-dependent. Flow cytometric and gene expression analyses revealed that VAT transplantation recapitulated the effects of obesity on microglial activation and IL1β gene expression, and visualization of hippocampal microglia revealed similar effects in vivo. Inducible ablation of IL1R1 in CX3CR1-expressing cells eliminated cognitive impairment in mice with dietary obesity and in transplant recipients and restored immunoquiescence in hippocampal microglia. These results indicate that visceral adipose NLRP3 impairs memory via IL1-mediated microglial activation, and suggest that NLRP3-IL1β signaling may underlie correlations between visceral adiposity and cognitive impairment in humans.

Authors

De-Huang Guo, Masaki Yamamoto, Caterina M. Hernandez, Hesam Khodadadi, Babak Baban, Alexis M. Stranahan

Capsular glycan recognition provides antibody-mediated immunity against tuberculosis

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Abstract

A better understanding of all immune components involved in protecting against M. tuberculosis infection is urgently needed to inform strategies for novel immunotherapy and tuberculosis (TB) vaccine development. While cell-mediated immunity is critical, increasing evidence supports that antibodies also have a protective role against TB. Yet, knowledge of protective antigens is limited. Analyzing sera from 97 US immigrants at various states of M. tuberculosis infection, we showed protective in vitro and in vivo efficacy of polyclonal IgG to the M. tuberculosis capsular polysaccharide arabinomannan (AM). Using recently developed glycan arrays, we established that anti-AM IgG induced in natural infection is highly heterogeneous in its binding specificity and differs in both its reactivity to oligosaccharide motifs within AM and its functions between BCG vaccination and/or controlled (latent) versus uncontrolled (TB) M. tuberculosis infection. We showed that anti-AM IgG from asymptomatic but not diseased individuals was protective, and provided data suggesting a potential role of IgG2 and specific AM oligosaccharides. Filling a gap in the current knowledge of protective antigens in humans, our data support the key role of the M. tuberculosis surface glycan AM and suggest the importance of targeting specific glycan epitopes within AM in antibody-mediated immunity against TB.

Authors

Tingting Chen, Caroline Blanc, Yanyan Liu, Elise Ishida, Sarah Singer, Jiayong Xu, Maju Joe, Elizabeth R. Jenny-Avital, John Chan, Todd L. Lowary, Jacqueline M. Achkar

Microbiota dependent production of butyrate is required for the bone anabolic activity of PTH

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PTH is a critical regulator of skeletal development that promotes both bone formation and bone resorption. Using microbiota depletion by wide-spectrum antibiotics and germ-free (GF) female mice we showed that the microbiota was required for PTH to stimulate bone formation and increase bone mass. Microbiota depletion lowered butyrate levels, a metabolite responsible for gut-bone communication, while reestablishment of physiologic levels of butyrate restored PTH-induced anabolism. The permissive activity of butyrate was mediated by GPR43 signaling in dendritic cells (DCs) and by GPR43-independent signaling in T cells. Butyrate was required for PTH to increase the number of bone marrow (BM) regulatory T cells (Tregs). Tregs stimulated production of the osteogenic Wnt ligand Wnt10b by BM CD8+ T cells, which activated Wnt dependent bone formation. Together, these data highlight the role that butyrate produced by gut luminal microbiota plays in triggering regulatory pathways which are critical for the anabolic action of PTH in bone.

Authors

Jau-Yi Li, Mingcan Yu, Subhashis Pal, Abdul Malik Tyagi, Hamid Dar, Jonathan Adams, M. Neale Weitzmann, Rheinallt M. Jones, Roberto Pacifici

Inhibiting the coregulator CoREST impairs Foxp3⁺ Treg function and promotes antitumor immunity

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Foxp3+ T-regulatory (Treg) cells are key to immune homeostasis, but the contributions of various large, multiprotein complexes that regulate gene expression remain unexplored. We analyzed the role in Tregs of the evolutionarily conserved CoREST complex consisting of a scaffolding protein, Rcor1 or Rcor2, plus Hdac1 or Hdac2 and Lsd1 enzymes. Rcor1, Rcor2 and Lsd1 were physically associated with Foxp3, and mice with conditional deletion of Rcor1 in Foxp3+ Tregs had decreased proportions of Tregs in peripheral lymphoid tissues, and increased Treg expression of IL-2 and IFN-γ compared to WT cells. Mice with conditional deletion of the gene encoding Rcor1 in their Tregs had reduced suppression of homeostatic proliferation, inability to maintain long-term allograft survival despite costimulation blockade, and enhanced antitumor immunity in syngeneic models. Comparable findings were seen in WT mice treated with CoREST complex bivalent inhibitors, which also altered the phenotype of human Tregs and impaired their suppressive function. Our data point to the potential for therapeutic modulation of Treg functions by pharmacologic targeting of enzymatic components of the CoREST complex, and contribute to an understanding of the biochemical and molecular mechanisms by which Foxp3 represses large gene sets and maintains the unique properties of this key immune cell.

Authors

Yan Xiong, Liqing Wang, Eros Di Giorgio, Tatiana Akimova, Ulf H. Beier, Rongxiang Han, Matteo Trevisanut, Jay H. Kalin, Philip A. Cole, Wayne W. Hancock

Type I interferon response drives neuroinflammation and synapse loss in Alzheimer disease

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Abstract

Type I interferon (IFN) is a key cytokine that curbs viral infection and cell malignancy. Previously, we have demonstrated a potent IFN immunogenicity of nucleic acid (NA)-containing amyloid fibrils in the periphery. Here, we investigated whether IFN is associated with β-amyloidosis inside the brain and contributes to neuropathology. An IFN-stimulated gene (ISG) signature was detected in the brains of multiple murine Alzheimer disease (AD) models, a phenomenon also observed in wild-type mouse brain challenged with generic NA-containing amyloid fibrils. In vitro, microglia innately responded to NA-containing amyloid fibrils. In AD models, activated ISG-expressing microglia exclusively surrounded NA-positive amyloid β plaques, which accumulated in an age-dependent manner. Brain administration of rIFNβ resulted in microglial activation and complement C3-dependent synapse elimination in vivo. Conversely, selective IFN receptor blockade effectively diminished the ongoing microgliosis and synapse loss in AD models. Moreover, we detected activated ISG-expressing microglia enveloping NA-containing neuritic plaques in post-mortem brains of AD patients. Gene expression interrogation revealed that IFN pathway was grossly upregulated in clinical AD and significantly correlated with disease severity and complement activation. Therefore, IFN constitutes a pivotal element within the neuroinflammatory network of AD and critically contributes to neuropathogenic processes.

Authors

Ethan R. Roy, Baiping Wang, Ying-Wooi Wan, Gabriel S. Chiu, Allysa L. Cole, Zhuoran Yin, Nicholas E. Propson, Yin Xu, Joanna L. Jankowsky, Zhandong Liu, Virginia M.Y. Lee, John Q. Trojanowski, Stephen D. Ginsberg, Oleg Butovsky, Hui Zheng, Wei Cao

Pancreatic triglyceride lipase mediates lipotoxic systemic inflammation

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Abstract

Visceral adipose tissue plays a critical role in numerous diseases. While imaging studies often show adipose involvement in abdominal diseases, their outcomes may vary from being a mild self limited illness to one with systemic inflammation and organ failure. We therefore compared the pattern of visceral adipose injury during acute pancreatitis and acute diverticulitis to determine its role in organ failure. Acute pancreatitis-associated adipose tissue had ongoing lipolysis in the absence of adipocyte triglyceride lipase (ATGL). Pancreatic lipase injection into mouse visceral adipose tissue hydrolyzed adipose triglyceride and generated excess non-esterified fatty acids (NEFA), which caused organ failure in the absence of acute pancreatitis. Pancreatic triglyceride lipase (PNLIP) increased in adipose tissue during pancreatitis and entered adipocytes by multiple mechanisms, hydrolyzing adipose triglyceride and generating excessive NEFA. During pancreatitis, obese PNLIP knockout mice, unlike obese adipocyte-specific ATGL knockouts, had lower visceral adipose tissue lipolysis, milder inflammation, lesser organ failure, and improved survival. PNLIP knockout mice, unlike ATGL knockouts, were protected from adipocyte-induced pancreatic acinar injury without affecting NEFA signaling or acute pancreatitis induction. Therefore during pancreatitis, unlike diverticulitis, PNLIP leaked into visceral adipose tissue can cause excessive visceral adipose tissue lipolysis independent of adipocyte-autonomous ATGL, and thereby worsen organ failure.

Authors

Cristiane de Oliveira, Biswajit Khatua, Pawan Noel, Sergiy Kostenko, Arup Bag, Bijinu Balakrishnan, Krutika S. Patel, Andre A. Guerra, Melissa N. Martinez, Shubham Trivedi, Ann E. McCullough, Dora M. Lam-Himlin, Sarah Navina, Douglas O. Faigel, Norio Fukami, Rahul Pannala, Anna Evans Phillips, Georgios I. Papachristou, Erin E. Kershaw, Mark E. Lowe, Vijay P. Singh

Graft-versus-host disease reduces lymph node display of tissue-restricted self-antigens and promotes autoimmunity

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Abstract

Acute graft-versus-host disease (GVHD) is initially triggered by alloreactive T cells, which damage peripheral tissues and lymphoid organs. Subsequent transition to chronic GVHD involves the emergence of autoimmunity although the underlying mechanisms driving this process are unclear. Here, we tested the hypothesis that acute GVHD blocks peripheral tolerance of autoreactive T cells by impairing lymph node (LN) display of peripheral tissue-restricted antigens (PTA). At the initiation of GVHD, LN fibroblastic reticular cells (FRC) rapidly reduced expression of genes regulated by DEAF1, an Autoimmune Regulator-like transcription factor required for intra-nodal expression of PTA. Subsequently, GVHD led to the selective elimination of the FRC population, and blocked the repair pathways required for its regeneration. We used a transgenic mouse model to show that the loss of presentation of an intestinal PTA by FRC during GVHD resulted in the activation of auto-aggressive T cells and gut injury. Finally, we show that FRC normally expressed a unique PTA gene signature that was highly enriched for genes expressed in the target organs affected by chronic GVHD. In conclusion, acute GVHD damages and prevents repair of the FRC network, thus disabling an essential platform for purging auto-reactive T cells from the repertoire.

Authors

Simone Dertschnig, Pamela Evans, Pedro Santos e Sousa, Teresa Manzo, Ivana R. Ferrer, Hans J. Stauss, Clare L. Bennett, Ronjon Chakraverty

Prevention of Connexin43 remodeling protects against duchenne muscular dystrophy cardiomyopathy

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Abstract

Aberrant expression of the cardiac gap junction protein connexin-43 (Cx43) has been suggested to play a role in the development of cardiac disease in the mdx mouse model of Duchenne muscular dystrophy (DMD), however a mechanistic understanding of this association is lacking. Here, we identified a reduction of phosphorylation of Cx43 serines S325/S328/S330 in human and mouse DMD hearts. We hypothesized that hypo-phosphorylation of Cx43 serine-triplet triggers pathological Cx43 redistribution to the lateral sides of cardiomyocytes (remodeling). Therefore, we generated knock-in mdx mice in which the Cx43 serine-triplet was replaced with either phospho-mimicking glutamic acids (mdxS3E) or non-phosphorylatable alanines (mdxS3A). The mdxS3E but not mdxS3A mice were resistant to Cx43 remodeling with a corresponding reduction of Cx43 hemichannel activity. MdxS3E cardiomyocytes displayed improved intracellular Ca2+ signaling and a reduction of NOX2/reactive oxygen species (ROS) production. Furthermore, mdxS3E mice were protected against inducible arrhythmias, related lethality and the development of cardiomyopathy. Inhibition of microtubule polymerization by colchicine reduced both NOX2/ROS and oxidized CaMKII, increased S325/S328/S330 phosphorylation and prevented Cx43 remodeling in mdx hearts. Together, these results demonstrate a mechanism of dystrophic Cx43-remodeling and suggest that targeting Cx43 may be a therapeutic strategy to prevent heart dysfunction and arrhythmias in DMD patients.

Authors

Eric Himelman, Mauricio A. Lillo, Julie Nouet, J. Patrick Gonzalez, Qingshi Zhao, Lai-Hua Xie, Hong Li, Tong Liu, Xander H.T. Wehrens, Paul D. Lampe, Glenn I. Fishman, Natalia Shirokova, Jorge E. Contreras, Diego Fraidenraich

HIV persists throughout deep tissues with repopulation from multiple anatomical sources

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Background. Understanding HIV dynamics across the human body is important for cure efforts. This goal has been hampered by technical difficulties and the challenge to obtain fresh tissues. Methods. This observational study evaluated 6 persons with HIV (4 virally suppressed with antiretroviral therapy and 2 with rebound viremia after stopping therapy) who provided blood serially before death and their bodies for rapid autopsy. HIV reservoirs were characterized by digital droplet PCR and single genome amplification and sequencing of full-length (FL) envelope HIV. Phylogeographic methods reconstructed HIV spread and generalized linear models tested for viral factors associated with dispersal. Results. Across participants, HIV DNA levels varied from ~0 to 659 copies/106 cells (IQR:22.9-126.5). A total of 605 intact FL env sequences were recovered in antemortem blood cells and across 28 tissues (IQR:5-9). Sequence analysis showed: 1) emergence of large, identical, intact HIV RNA populations in blood after stopping therapy, which repopulated tissues throughout the body, 2) multiple sites acted as hubs for HIV dissemination but blood and lymphoid tissues were the main source, and 3) viral exchanges occurred within brain areas and across the blood brain barrier, and 4) migration was associated with low HIV divergence between sites and higher diversity at the recipient site. Conclusion. HIV reservoirs persist in all deep tissues, and blood is the main source of dispersal. This may explain why eliminating HIV susceptibility in circulating T cells via bone marrow transplants allowed some people with HIV to have therapy free remission, even though deeper tissue reservoirs were not targeted. Trial registration. Not applicable. Funding. National Institute of Health Grants (P01 AI31385, P30 AI036214, AI131971-01, AI120009AI036214,HD094646, AI027763, AI134295, AI68636).

Authors

Antoine Chaillon, Sara Gianella, Simon Dellicour, Stephen A. Rawlings, Timothy E. Schlub, Michelli Faria De Oliveira, Caroline Ignacio, Magali Porrachia, Bram Vrancken, Davey M. Smith

Bruton tyrosine kinase deficiency augments NLRP3 inflammasome activation and causes IL-1β-mediated colitis

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Abstract

Bruton tyrosine kinase (BTK) is present in a wide variety of cells and may thus have important non-B cell functions. Here we explored the function of this kinase in macrophages with studies of its regulation of the NLRP3 inflammasome. We found that bone marrow-derived macrophages (BMDMs) from BTK-deficient mice or monocytes from X-linked agammaglobulinemia patients exhibit increased NLRP3 inflammasome activity; this was also the case with BMDMs exposed to low doses of BTK inhibitor such as ibrutinib and monocytes from chronic lymphocytic leukemia patients being treated with ibrutinib. In mechanistic studies, we found that BTK binds to NLRP3 during the priming phase of inflammasome activation and in doing so inhibits LPS/nigericin-induced assembly of the NLRP3 inflammasome during the activation phase of inflammasome activation. This inhibitory effect was caused by BTK inhibition of PP2A-mediated dephosphorylation of Ser5 in the pyrin domain of NLRP3. Finally, we showed that BTK-deficient mice are subject to severe experimental colitis and such colitis is normalized by administration of anti-IL-β or an inhibitor of IL-1β signaling, anakinra. Together, these studies strongly suggest that BTK functions as a physiologic inhibitor of NLRP3 inflammasome activation; they thereby explain the fact that XLA patients are prone to develop Crohn’s disease.

Authors

Liming Mao, Atsushi Kitani, Eitaro Hiejima, Kim Montgomery-Recht, Wenchang Zhou, Ivan Fuss, Adrian Wiestner, Warren Strober

Enasidenib drives human erythroid differentiation independently of isocitrate dehydrogenase 2

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Abstract

Cancer–related anemia is present in over 60% of newly diagnosed cancer patients and is associated with substantial morbidity and high medical costs. Drugs that enhance erythropoiesis are urgently required to decrease transfusion rates and improve quality of life. Clinical studies have observed an unexpected improvement in hemoglobin and red blood cell (RBC) transfusion-independence in AML patients treated with the isocitrate dehydrogenase 2 (IDH2) mutant-specific inhibitor, enasidenib, leading to improved quality of life without a reduction in AML disease burden. Here, we demonstrate that enasidenib enhanced human erythroid differentiation of hematopoietic progenitors. The phenomenon was not observed with other IDH1/2 inhibitors and occurred in IDH2-deficient CRIPSR-engineered progenitors independently of D-2-hydroxyglutarate. The effect of enasidenib on hematopoietic progenitors was mediated by protoporphyrin accumulation, driving heme production and erythroid differentiation in committed CD71+ progenitors rather than hematopoietic stem cells. Our results position enasidenib as a promising therapeutic agent for improvement of anemia and provide the basis for a clinical trial using enasidenib to decrease transfusion dependence in a wide array of clinical contexts.

Authors

Ritika Dutta, Tian Yi Zhang, Thomas Köhnke, Daniel Thomas, Miles Linde, Eric Gars, Melissa Stafford, Satinder Kaur, Yusuke Nakauchi, Raymond Yin, Armon Azizi, Anupama Narla, Ravindra Majeti

High residual C-peptide likely contributes to glycemic control in type 1 diabetes

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Abstract

BACKGROUND. Residual C-peptide is detected in many people for years following the diagnosis of type 1 diabetes; however, the physiologic significance of low levels of detectable C-peptide is not known. METHODS. We studied sixty-three adults with type 1 diabetes classified by peak mixed-meal tolerance test (MMTT) C-peptide as negative (<0.007; n =15), low (0.017–0.200; n =16), intermediate (>0.200–0.400; n =15), or high (>0.400 pmol/mL; n =17). We compared the groups’ glycemia from continuous glucose monitoring (CGM), β-cell secretory responses from a glucose-potentiated arginine (GPA) test, insulin sensitivity from a hyperinsulinemia euglycemic (EU) clamp, and glucose counterregulatory responses from a subsequent hypoglycemic (HYPO) clamp. RESULTS. Low and intermediate MMTT C-peptide groups did not exhibit β-cell secretory responses to hyperglycemia, whereas the high C-peptide group showed increases in both C-peptide and proinsulin (P ≤0.01). All groups with detectable MMTT C-peptide demonstrated acute C-peptide and proinsulin responses to arginine that were positively correlated with peak MMTT C-peptide (P <0.0001 for both analytes). During the EU-HYPO clamp, C-peptide levels were proportionately suppressed in the low, intermediate, and high C-peptide compared to the negative group (P ≤0.0001), whereas glucagon increased from EU to HYPO only in the high C-peptide group compared to negative (P =0.01). CGM demonstrated lower mean glucose and more time-in-range for the high C-peptide group. CONCLUSION. These results indicate that in adults with type 1 diabetes, β-cell responsiveness to hyperglycemia and α-cell responsiveness to hypoglycemia are only observed at high levels of residual C-peptide that likely contribute to glycemic control.

Authors

Michael R. Rickels, Carmella Evans-Molina, Henry T. Bahnson, Alyssa Ylescupidez, Kristen J. Nadeau, Wei Hao, Mark A. Clements, Jennifer L. Sherr, Richard E. Pratley, Tamara S. Hannon, Viral N. Shah, Kellee M. Miller, Carla J. Greenbaum