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Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in 2012 in the Kingdom of Saudi Arabia and has caused over 2400 cases and more than 800 deaths. Epidemiological studies identified diabetes as the primary comorbidity associated with severe and/or lethal MERS-CoV infection. Understanding how diabetes affects MERS is important due to the global burden of diabetes and pandemic potential of MERS-CoV. We used a model in which mice were made susceptible to MERS-CoV by expressing human DPP4 and type 2 diabetes was induced by administering a high fat diet. Upon infection with MERS-CoV, diabetic mice had a prolonged phase of severe disease and delayed recovery which was independent of virus titers. Histological analysis revealed that diabetic mice had delayed inflammation which was then prolonged through 21 dpi. Diabetic mice had fewer inflammatory monocyte/macrophages and CD4+ T cells which correlated with lower levels of Ccl2 and Cxcl10 expression. Diabetic mice also had lower levels of Tnfa, Il6, Il12b, and Arg1 expression and higher levels of Il17a expression. These data suggest that the increased disease severity observed in individuals with MERS and comorbid type 2 diabetes is likely due to a dysregulated immune response which results in more severe and prolonged lung pathology.
Authors
Kirsten A. Kulcsar, Christopher M. Coleman, Sarah E. Beck, Matthew B. Frieman
Abstract
Increased fibrosis is a characteristic remodeling response to biomechanical and neurohumoral stress and a determinant of cardiac mechanical and electrical dysfunction in disease. Stress-induced activation of cardiac fibroblasts (CF) is a critical step in the fibrotic response, although the precise sequence of events underlying activation of these critical cells in vivo remain unclear. Here, we test the hypothesis that a βIV-spectrin/STAT3 complex is essential for maintenance of a quiescent phenotype (basal non-activated state) in CFs. We report increased fibrosis, decreased cardiac function, and electrical impulse conduction defects in genetic and acquired mouse models of βIV-spectrin deficiency. Loss of betaIV-spectrin function promotes STAT3 nuclear accumulation and transcriptional activity, altered gene expression and CF activation. Furthermore, we demonstrate that a quiescent phenotype may be restored in βIV-spectrin deficient fibroblasts by expressing a βIV-spectrin fragment including the STAT3-binding domain or through pharmacological STAT3 inhibition. We find that in vivo STAT3 inhibition abrogates fibrosis and cardiac dysfunction in the setting of global βIV-spectrin deficiency. Finally, we demonstrate that fibroblast-specific deletion of βIV-spectrin is sufficient to induce fibrosis and decreased cardiac function. We propose that the βIV-spectrin/STAT3 complex is a determinant of fibroblast phenotype and fibrosis, with implications for remodeling response in cardiovascular disease.
Authors
Nehal J. Patel, Drew M. Nassal, Amara D. Greer-Short, Sathya D. Unudurthi, Benjamin W. Scandling, Daniel Gratz, Xianyao Xu, Anuradha Kalyanasundaram, Vadim V. Fedorov, Federica Accornero, Peter J. Mohler, Keith J. Gooch, Thomas J. Hund
Abstract
Filoviruses of the genus Ebolavirus include five species with marked differences in their ability to cause disease in humans. From the highly virulent Ebola virus to the seemingly nonpathogenic Reston virus, case-fatality rates can range between 0-90%. In order to understand the molecular basis of these differences it is imperative to establish disease models that recapitulate human disease as faithfully as possible. Non-human primates are the gold-standard models for filovirus pathogenesis, but comparative studies are skewed by the fact that Reston virus infection can be lethal for NHP. Here we have used HLA-A2 transgenic, NOD-scid-interleukin 2γ receptor knockout (NSG-A2) mice reconstituted with human hematopoiesis to compare Ebola virus and Reston virus pathogenesis in a human-like environment. While significantly less pathogenic than Ebola virus, Reston virus killed 20% of infected mice, a finding that was linked to exacerbated inflammation and viral replication in the liver. In addition, ‘humanized’ mice recapitulated the case-fatality ratios of different Ebolavirus species in humans. Our findings point out at humanized mice as a putative model to test the pathogenicity of newly discovered filoviruses, and warrants further investigations on Reston virus pathogenesis in humans.
Authors
Beatriz Escudero-Pérez, Paula Ruibal, Monika Rottstegge, Anja Lüdtke, Julia R. Port, Kristin Hartmann, Sergio Gómez-Medina, Juergen Müller-Guhl, Emily V. Nelson, Susanne Krasemann, Estefanía Rodríguez, César Muñoz-Fontela
Abstract
Severe asthma with fungal sensitization (SAFS) defines a subset of human asthmatics with allergy to one or more fungal species and difficult to control asthma. We have reported that human asthmatics sensitized to fungi have worse lung function and a higher degree of atopy, which was associated with higher IL-1RA levels in bronchoalveolar lavage fluid. IL-1RA further demonstrated a significant negative association with bronchial hyperresponsiveness to methacholine. Here, we show that IL-1α and IL-1β are elevated in both bronchoalveolar lavage fluid and sputum from human asthmatics sensitized to fungi, implicating an association with IL-1α, IL-1β or IL-1RA in fungal asthma severity. In an experimental model of fungal-associated allergic airway inflammation, we demonstrate that IL-1R1 signaling promotes type 1 (IFN-γ, CXCL9, CXCL10) and type 17 (IL-17A, IL-22) responses that were associated with neutrophilic inflammation and increased airway hyperreactivity. Each of these were exacerbated in the absence of IL-1RA. Administration of human recombinant IL-1RA (Kineret/Anakinra) during fungal-associated allergic airway inflammation improved airway hyperreactivity and lowered type 1 and type 17 responses. Taken together, these data suggest that IL-1 receptor signaling contributes to fungal asthma severity via immunopathogenic type 1 and type 17 responses and can be targeted for improving allergic asthma severity.
Authors
Matthew S. Godwin, Kristen M. Reeder, Jaleesa M. Garth, Jonathan P. Blackburn, MaryJane Jones, Zhihong Yu, Sadis Matalon, Annette T. Hastie, Deborah A. Meyers, Chad Steele
Abstract
Lymphatic malformations (LMs) are congenital, non-neoplastic vascular malformations associated with post-zygotic activating PIK3CA mutations. The mutation spectrum within LMs is narrow, with the majority having one of three “hotspot” mutations. Despite this relative genetic homogeneity, clinical presentations differ dramatically. We used molecular inversion probes and droplet digital polymerase chain reaction to perform deep, targeted sequencing of PIK3CA in 271 affected and unaffected tissue samples from 81 individuals with isolated LMs and retrospectively collected clinical data. Pathogenic PIK3CA mutations were identified in affected LM tissue in 64 individuals (79%) with isolated LMs, with variant allele fractions (VAFs) ranging from 0.1 to 13%. Initial analyses revealed no correlation between VAF and phenotype variables. Recognizing that different mutations activate PI3K to varying degrees, we developed a metric, the genotype-adjusted VAF (GVAF), to account for differences in mutation strength, and found significantly higher GVAFs in LMs with more severe clinical characteristics including orofacial location or microcystic structure. In addition to providing insight into LM pathogenesis, we believe GVAF may have broad applicability for genotype-phenotype analyses in mosaic disorders.
Authors
Kaitlyn Zenner, Chi Vicky Cheng, Dana M. Jensen, Andrew E. Timms, Giridhar Shivaram, Randall Bly, Sheila Ganti, Kathryn B. Whitlock, William B. Dobyns, Jonathan Perkins, James T. Bennett
Abstract
miR-511-3p, encoded by CD206/Mrc1, was demonstrated to reduce allergic inflammation and promote alternative (M2) macrophage polarization. Here, we sought to elucidate the fundamental mechanism by which miR-511-3p attenuates allergic inflammation and promotes macrophage polarization. Compared with wild-type mice, the allergen-challenged Mrc1-/- mice showed increased airway hyper-responsiveness (AHR) and inflammation. However, this increased AHR and inflammation were significantly attenuated when these mice were pre-transduced with adeno-associated virus (AAV)-miR-511-3p. Gene expression profiling of macrophages identified Ccl2 as one of the major genes that was highly expressed in M2 macrophages but antagonized by miR-511-3p. The interaction between miR-511-3p and Ccl2 was confirmed by in silico analysis and mRNA-miRNA pull-down assay. Further evidence for the inhibition of Ccl2 by miR-511-3p was given by reduced levels of Ccl2 in supernatants of miR-511-3p transduced macrophages and in bronchoalveolar lavage fluids of AAV-miR-511-3p-infected Mrc1-/- mice. Mechanistically, we demonstrated that Ccl2 promotes M1 macrophage polarization by activating RhoA signaling through Ccr2. The interaction between Ccr2 and RhoA was also supported by co-immunoprecipitation assay. Importantly, inhibition of RhoA signaling suppressed cockroach allergen-induced AHR and lung inflammation. These findings suggest a novel mechanism by which miR-511-3p regulates allergic inflammation and macrophage polarization by targeting Ccl2 and its downstream Ccr2/RhoA axis.
Authors
Danh C. Do, Jie Mu, Xia Ke, Karan Sachdeva, Zili Qin, Mei Wan, Faoud T. Ishmael, Peisong Gao
Abstract
The glucagon-like peptide 1 receptor agonist exenatide improves glycemic control by several and not completely understood mechanisms. Herein, we examined the effects of chronic intravenous exenatide infusion on insulin sensitivity, β- and α-cell function and relative volumes, islet cell apoptosis and replication in nondiabetic non-human primates (baboons). At baseline, baboons received a 2-step hyperglycemic clamp followed by an L-arginine bolus (HC/A). After HC/A, baboons underwent a partial pancreatectomy (tail removal) and received a continuous exenatide (n = 12) or saline (n = 12) infusion for 13 weeks. At the end of treatment, HC/A was repeated and the remnant pancreas (head-body) harvested. Insulin sensitivity increased dramatically after exenatide treatment and was accompanied by a decrease in insulin and C-peptide secretion, while the insulin secretion/insulin resistance (disposition) index increased by approximately 2-fold. β-, α-, and δ-cell relative volumes in exenatide-treated baboons were significantly increased compared to saline-treated controls, primarily as the result of increased islet cell replication. Features of cellular stress and secretory dysfunction were present in islets of saline-treated baboons and absent in islets of exenatide-treated baboons. In conclusion, chronic administration of exenatide exerts proliferative and cytoprotective effects on β-, α-, and δ-cells and produces a robust increase in insulin sensitivity in non-human primates.
Authors
Teresa Vanessa Fiorentino, Francesca Casiraghi, Alberto M. Davalli, Giovanna Finzi, Stefano La Rosa, Paul B. Higgins, Gregory A. Abrahamian, Alessandro Marando, Fausto Sessa, Carla Perego, Rodolfo Guardado- Mendoza, Subhash Kamath, Andrea Ricotti, Paolo Fiorina, Giuseppe Daniele, Ana M. Paez, Francesco Andreozzi, Raul A. Bastarrachea, Anthony G. Comuzzie, Amalia Gastaldelli, Alberto O. Chavez, Eliana S. Di Cairano, Patrice A. Frost, Livio Luzi, Edward J. Dick, Jr., Glenn A. Halff, Ralph A. DeFronzo, Franco Folli
Abstract
Itch induces scratching that removes irritants from the skin, whereas pain initiates withdrawal or avoidance of tissue damage. Whilst pain arises from both the skin and viscera, we investigated whether pruritogenic irritant mechanisms also function within visceral pathways. We show that subsets of colon-innervating sensory neurons in mice express, either individually or in combination, the pruritogenic receptors Tgr5 and the Mas-gene-related G protein-coupled receptors, Mrgpra3 and Mrgpra11. Agonists of these receptors activated subsets of colonic sensory neurons and evoked colonic afferent mechanical hypersensitivity via a TRPA1-dependent mechanism. In vivo intra-colonic administration of individual TGR5, MRGPRA3, or MRGPRC11 agonists induced pronounced visceral hypersensitivity to colorectal distension. Co-administration of these agonists as an ‘itch cocktail’ augmented hypersensitivity to colorectal distension and changed mouse behaviour. These irritant mechanisms were maintained and enhanced in a model of chronic visceral hypersensitivity relevant to irritable bowel syndrome. Neurons from human dorsal root ganglia also expressed TGR5 as well as the human ortholog MRGPRX1 and showed increased responsiveness to pruritogenic agonists in pathological states. These data support the existence of an irritant-sensing system in the colon that is a visceral representation of the itch pathways found in skin, thereby contributing to sensory disturbances accompanying common intestinal disorders.
Authors
Joel Castro, Andrea M. Harrington, TinaMarie Lieu, Sonia Garcia-Caraballo, Jessica Maddern, Gudrun Schober, Tracey O'Donnell, Luke Grundy, Amanda L. Lumsden, Paul E. Miller, Andre Ghetti, Martin S. Steinhoff, Daniel P. Poole, Xinzhong Dong, Lin Chang, Nigel W. Bunnett, Stuart M. Brierley
Efficient ADCC- killing of meningioma by avelumab and a high-affinity natural killer cell line, haNK
Abstract
Meningiomas are the most common adult primary tumor of the central nervous system, but there are no known effective medical therapies for recurrent meningioma, particularly for WHO grade II and III tumors. Meningiomas arise from the meninges, located outside the blood-brain barrier, and therefore may be directly targeted by antibody-mediated immunotherapy. We found that PD-L1 was highly expressed in multiple human malignant meningioma cell lines and patient tumor samples. PD-L1 was targeted with the anti-PD-L1 antibody avelumab and directed natural killer cells to mediate antibody-dependent cellular cytotoxicity (ADCC) of PD-L1-expressing meningioma tumors both in vitro and in vivo. ADCC of meningioma cells was significantly increased in target cells that upregulated PD-L1 expression and, conversely, abrogated in tumor cells that were depleted of PD-L1. Additionally, the high-affinity natural killer cell line, haNK, outperformed healthy donor NK cells in meningioma ADCC. Together, these data support a clinical trial designed to target PD-L1 with avelumab and haNK cells, potentially offering a novel immunotherapeutic approach for patients with malignant meningioma.
Authors
Amber J. Giles, Shuyu Hao, Michelle R. Padget, Hua Song, Wei Zhang, John Lynes, Victoria E. Sanchez, Yang Liu, Jinkyu Jung, Xiaoyu Cao, Rika Fujii, Randy L. Jensen, David Gillespie, Jeffrey Schlom, Mark R. Gilbert, Edjah K. Nduom, Chunzhang Yang, John H. Lee, Patrick Soon-Shiong, James W. Hodge, Deric M. Park
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by pathologic T cell-B cell interactions and autoantibody production. Defining the T cell populations that drive B cell responses in SLE may enable design of therapies that specifically target pathologic cell subsets. Here we evaluated the phenotypes of CD4+ T cells in the circulation of 52 SLE patients drawn from multiple cohorts and identified a highly expanded PD-1hi CXCR5- CD4+ T cell population. Cytometric, transcriptomic, and functional assays demonstrated that PD-1hi CXCR5- CD4+ T cells from SLE patients are T peripheral helper (Tph) cells, a CXCR5- T cell population that stimulates B cell responses via IL-21. The frequency of Tph cells, but not Tfh cells, correlated with both clinical disease activity and the frequency of CD11c+ B cells in SLE patients. PD-1hi CD4+ T cells were found within lupus nephritis kidneys and correlated with B cell numbers in kidney. Both IL-21 neutralization and CRISPR-mediated deletion of MAF abrogated the ability of Tph cells to induce memory B cell differentiation into plasmablasts in vitro. These findings identify Tph cells a highly expanded T cell population in SLE and suggest a key role for Tph cells in stimulating pathologic B cell responses.
Authors
Alexandra V. Bocharnikov, Joshua Keegan, Vanessa S. Wacleche, Ye Cao, Chamith Y. Fonseka, Guoxing Wang, Eric Muise, Kelvin X. Zhang, Arnon Arazi, Gregory Keras, Zhihan J. Li, Yujie Qu, Michael F. Gurish, Michelle Petri, Jill P. Buyon, Chaim Putterman, David Wofsy, Judith A. James, Joel M. Guthridge, Betty Diamond, Jennifer H. Anolik, Matthew F. Mackey, Stephen E. Alves, Peter A. Nigrovic, Karen H. Costenbader, Michael B. Brenner, James A. Lederer, Deepak A. Rao
Abstract
Tissue engineering is a promising approach to address organ shortages currently limiting clinical transplantation. “Off-the-shelf” engineered vascularized organs will likely use allogeneic endothelial cells (ECs) to construct microvessels required for graft perfusion. Vasculogenic ECs can be differentiated from committed progenitors (human endothelial colony forming cells or HECFCs) without risk of mutation or teratoma formation associated with reprogrammed stem cells. Like other ECs, these cells basally express both class I and class II major histocompatibility complex (MHC) molecules, bind donor-specific antibody (DSA), activate alloreactive T effector memory cells, and initiate rejection in the absence of donor leukocytes. We report here that CRISPR/Cas9-mediated dual ablation of β2-microglobulin and CIITA in HECFC-derived ECs eliminates both class I and II MHC expression while retaining EC functions and vasculogenic potential. Importantly, dually ablated ECs no longer bind human DSA or activate allogeneic CD4+ effector memory T cells and are resistant to killing by CD8+ alloreactive cytotoxic T lymphocytes in vitro and in vivo. Despite absent class I MHC molecules, these ECs do not activate or elicit cytotoxic activity from allogeneic natural killer cells. These data suggest that HECFC-derived ECs lacking MHC molecule expression can be utilized for engineering vascularized grafts that evade allorejection.
Authors
Jonathan Merola, Melanie Reschke, Richard W. Pierce, Lingfeng Qin, Susann Spindler, Tania Baltazar, Thomas D. Manes, Francesc Lopez-Giraldez, Guangxin Li, Laura G. Bracaglia, Catherine Xie, Nancy Kirkiles-Smith, W. Mark Saltzman, Gregory T. Tietjen, George Tellides, Jordan S. Pober
Abstract
Depletion of epithelial cells after lung injury prompts proliferation and epithelial-mesenchymal transition (EMT) of progenitor cells, which repopulates the lost epithelial layer. To investigate cell proliferative function of human oncoprotein MDM2, we generated mouse models targeting human MDM2 expression in either lung Club or alveolar cells after doxycycline treatment. We report that MDM2 expression in lung Club or alveolar cells activates DNA replication specifically in lung progenitor cells only after chemical- or radiation-induced lung injury irrespective of their p53 status. Activation of DNA replication by MDM2 triggered by injury leads to the proliferation of lung progenitor cells and restoration of the lost epithelial layers. Mouse lung with no mdm2 allele loses their ability to replicate DNA, whereas, loss of one mdm2 allele compromises this function, demonstrating the requirement of endogenous MDM2. We show that the p53-independent ability of MDM2 to activate Akt signaling is essential for initiating DNA replication in lung progenitor cells. Furthermore, MDM2 activates the Notch signaling pathway and expression of EMT markers indicative of epithelial regeneration. This is the first report demonstrating direct p53-independent participation of MDM2 in progenitor cell proliferation and epithelial repair after lung injury, distinct from a p53-degrading anti-apoptotic effect preventing injury.
Authors
Shilpa Singh, Catherine A. Vaughan, Christopher Rabender, Ross Mikkelsen, Sumitra Deb, Swati Palit Deb
Abstract
Aberrant activation of the NF-κB transcription factors underlies chemoresistance in various cancer types including colorectal cancer (CRC). Targeting the activating mechanisms, particularly with inhibitors to the upstream IκB kinase (IKK) complex, is a promising strategy to augment the effect of chemotherapy. However, clinical success has been limited largely due to low specificity and toxicities of tested compounds. In solid cancers, the IKK kinases is driven predominantly by the Toll-like/Interlekin-1 receptor family members, which signal through the Interleukin-1 Receptor-Associated Kinases (IRAKs), with isoform 4 (or IRAK4) being the most critical. The pathogenic role and therapeutic value of IRAK4 in CRC has not been investigated. We found that IRAK4 inhibition significantly abrogates colitis-induced neoplasm in APCMin/+ mice, and bone marrow transplant experiments showed an essential role of IRAK4 in immune cells during neoplastic progression. Chemotherapy significantly enhances IRAK4 and NF-κB activity in CRC cells through upregulating TLR9 expression, which can in turn be suppressed by IRAK4 and IKK inhibitors, suggesting a feedforward pathway that protects CRC cells from chemotherapy. Lastly, increased tumor phospho-IRAK4 staining or IRAK4 mRNA expression are associated with significantly worse survival in CRC patients. Our results support targeting IRAK4 to improve the effects of chemotherapy and outcomes in CRC.
Authors
Qiong Li, Yali Chen, Daoxiang Zhang, Julie Grossman, Lin Li, Namrata Khurana, Hongmei Jiang, Patrick Grierson, John Herndon, David G. DeNardo, Grant A. Challen, Jingxia Liu, Marianna B. Ruzinova, Ryan C. Fields, Kian-Huat Lim
Abstract
Dendritic cells (DCs) are crucial to balance protective immunity and autoimmune inflammatory processes. Expression of CD83 is a well-established marker for mature DCs although its physiological role is still not completely understood. Using a DC-specific CD83 conditional KO mouse (CD83ΔDC) we provide new insights into the function of CD83 within this cell type. Interestingly, CD83-deficient DCs produced drastically increased IL-2 levels and displayed higher expression of the co-stimulatory molecules CD25 and OX40L, which causes superior induction of antigen-specific T cell responses and compromises Treg suppressive functions. This also directly translates into accelerated immune responses in vivo. Upon Salmonella typhimurium and Listeria monocytogenes infection, CD83ΔDC mice cleared both pathogens more efficiently, and CD83-deficient DCs expressed increased IL-12 levels after bacterial encounter. Using the experimental autoimmune encephalomyelitis (EAE) model, autoimmune inflammation was dramatically aggravated in CD83ΔDC mice, while resolution of inflammation was strongly reduced. This phenotype was associated with increased cell influx into the CNS accompanied by elevated Th17 cell numbers. Concomitantly, CD83ΔDC mice had reduced Treg numbers in peripheral lymphoid organs. In summary, we show that CD83 ablation on DCs results in enhanced immune responses by dysregulating tolerance mechanisms and thereby impairing resolution of inflammation, which also demonstrates high clinical relevance.
Authors
Andreas B. Wild, Lena Krzyzak, Katrin Peckert, Lena Stich, Christine Kuhnt, Alina Butterhof, Christine Seitz, Jochen Mattner, Niklas Grüner, Maximilian Gänsbauer, Martin Purtak, Didier Soulat, Thomas H. Winkler, Lars Nitschke, Elisabeth Zinser, Alexander Steinkasserer
Abstract
Myostatin is a negative regulator of muscle growth and metabolism and its inhibition in mice improves insulin sensitivity, increases glucose uptake into skeletal muscle, and decreases total body fat. A recently described mammalian protein called Mss51 is significantly downregulated with myostatin inhibition. In vitro disruption of Mss51 results in increased levels of ATP, β-oxidation, glycolysis and oxidative phosphorylation. To determine the in vivo biological function of Mss51 in mice, we disrupted the Mss51 gene by CRISPR/Cas9 and found that Mss51 KO mice have normal muscle weights and fiber-type distribution but reduced fat pads. Myofibers isolated from Mss51 KO mice showed an increased oxygen consumption rate compared to WT controls, indicating an accelerated rate of skeletal muscle metabolism. The expression of genes related to oxidative phosphorylation and fatty acid β-oxidation were enhanced in skeletal muscle of Mss51 KO mice compared to that of WT mice. We found that mice lacking Mss51 and challenged with a high fat diet were resistant to diet-induced weight gain, had increased whole-body glucose turnover and glycolysis rate, and increased systemic insulin sensitivity and fatty acid β-oxidation. These findings demonstrate that Mss51 modulates skeletal muscle mitochondrial respiration and regulates whole-body glucose and fatty acid metabolism, making it a potential target for obesity and diabetes.
Authors
Yazmin I. Rovira Gonzalez, Adam L, Moyer, Nicolas J. LeTexier, August D. Bratti, Siyuan Feng, Congshan Sun, Ting Liu, Jyothi Mula, Pankhuri Jha, Shama R. Iyer, Richard M. Lovering, Brian O'Rourke, Hye Lim Noh, Sujin Suk, Jason K. Kim, George K.E. Umanah, Kathryn R. Wagner
Abstract
Perturbations in biomechanical stimuli during cardiac development contribute to congenital cardiac defects such as Hypoplastic Left Heart Syndrome (HLHS). This study sought to identify stretch-responsive pathways involved in cardiac development. microRNA (miRNA)-Sequencing identified miR-486 as being increased in cardiomyocytes exposed to cyclic stretch in vitro (63%, p<0.002). The right ventricles of HLHS patients experience increased stretch and have a trend towards higher miR-486 levels 4.9-fold (p=0.08). Sheep RVs dilated from excessive pulmonary blood flow have 60% more miR-486 vs. control RVs (p<0.05). The left ventricles of newborn mice treated with miR-486 mimic are 16.9%-24.6% larger (p<0.01) and display 2.48 fold increase in cardiomyocyte proliferation (p<0.01). miR-486 treatment decreases FoxO1 and Smad signaling, while increasing the protein levels of Stat1. Stat1 associates with Gata4 and Serum Response Factor (Srf), two key cardiac transcription factors whose protein levels increase in response to miR-486. This is the first report of a stretch-responsive miRNA that increases the growth of the ventricle in vivo.
Authors
Stephan Lange, Indroneal Banerjee, Katrina Carrion, Ricardo Serrano, Louisa Habich, Rebecca Kameny, Luisa Lengenfelder, Nancy Dalton, Rudolph Meili, Emma Börgeson, Kirk Peterson, Marco Ricci, Joy Lincoln, Majid Ghassemian, Jeffrey R. Fineman, Juan C. del Álamo, Vishal Nigam
Abstract
Background: Epicardial adipose tissue (EAT) is the visceral fat depot of the heart. Inflammation of EAT is thought to contribute to coronary artery disease (CAD). Therefore, we hypothesized that the EAT of patients with CAD would have increased inflammatory gene expression compared to controls without CAD. Methods: 26 patients referred for cardiac surgery with (n=13) or without CAD (n=13) were consented. Samples of EAT and subcutaneous adipose tissue (SAT) were obtained at the time of surgery. Gene expression analysis was performed using Affymetrix Human Gene 1.0 ST arrays. Differential regulation was defined as a 1.5 fold change (ANOVA p<0.05). Results: When comparing SAT and EAT of controls, 693 genes were differentially expressed. 805 genes were differentially expressed between SAT and EAT in cases. Expression of 326 genes was different between EAT of cases and controls; expression of 14 genes was increased in cases, while 312 were increased in controls. qRT-PCR confirmed that there was no difference in expression of major inflammatory genes (CCL2, CCR2, TNFα, IL6, IL8, PAI1) between cases and controls. Immunohistochemistry demonstrated that there were more macrophages in EAT than SAT, but that there was no difference in the number or activation state between cases and controls. Conclusion: In contrast to prior studies, we did not find increased inflammatory gene expression in the EAT of patients with CAD in comparison to controls without CAD. We conclude that specific adipose tissue organ, rather than CAD status, is responsible for the majority of differential gene expression.
Authors
Timothy P. Fitzgibbons, Nancy Lee, Khanh-Van Tran, Sara Nicoloro, Mark Kelly, Stanley K.C. Tam, Michael P. Czech
Abstract
The cardiac hormone atrial natriuretic peptide (ANP) is a central regulator of blood volume and a therapeutic target in hypertension and heart failure. Enhanced ANP activity in such conditions through inhibition of the degradative enzyme neprilysin has shown clinical efficacy, but is complicated by consequences from simultaneous accumulation of a heterogeneous array of other hormones. Targets for specific ANP enhancement have not been available. Here, we describe a cis-acting antisense transcript (NPPA-AS1) which negatively regulates ANP expression in human cardiomyocytes. We show that NPPA-AS1 regulates ANP expression via facilitating interaction of the NPPA repressor REST (RE1-silencing transcription factor) binding to its promoter, rather than base-pairing with ANP mRNA. Expression of ANP mRNA and NPPA-AS1 was increased and correlated in isolated strained human cardiomyocytes and in hearts from patients with advanced heart failure. Further, inhibition of NPPA-AS1 in vitro and in vivo resulted in increased myocardial expression of ANP, increased circulating ANP, increased renal cGMP and lower blood pressure. The effects of NPPA-AS1 inhibition on NPPA expression in human cardiomyocytes were further marked under cell-strain conditions. Collectively, these results implicate the antisense transcript NPPA-AS1 as part of a physiologic self-regulatory ANP circuit and a viable target for specific ANP augmentation.
Authors
Selvi Celik, Mardjaneh Karbalaei Sadegh, Michael Morley, Carolina Roselli, Patrick T. Ellinor, Thomas Cappola, J. Gustav Smith, Olof Gidlof
Abstract
Atrial fibrillation (AF) is the most common heart rhythm disorder and a major cause of stroke. Unfortunately, current therapies for AF are suboptimal, largely because the molecular mechanisms underlying AF are poorly understood. Since the autonomic nervous system is thought to increase vulnerability to AF, we investigated in a rapid atrial pacing (RAP) canine model the anatomic and electrophysiological characteristics of autonomic remodeling in different regions of the left atrium. RAP led to marked hypertrophy of parent nerve bundles in the posterior left atrium (PLA), resulting in a global increase in parasympathetic and sympathetic innervation throughout the left atrium. Parasympathetic fibers were more heterogeneously distributed in the PLA when compared to other left atrial regions; this led to greater fractionation and disorganization of AF electrograms in the PLA. Computational modeling revealed that heterogeneously distributed parasympathetic activity exacerbates sympathetic substrate for wave break and reentry. We further discovered that levels of Nerve Growth Factor (NGF) were greatest in the left atrial appendage (LAA), where AF was most organized. Preferential NGF release by the LAA - likely a direct function of frequency and regularity of atrial stimulation - may have important implications for creation of a vulnerable AF substrate.
Authors
Georg Gussak, Anna Pfenniger, Lisa M. Wren, Mehul Gilani, Wenwei Zhang, Shin Yoo, David A. Johnson, Amy Burrell, Brandon Benefield, Gabriel M. Knight, Bradley P. Knight, Rod Passman, Jeffrey J. Goldberger, Gary Aistrup, J. Andrew Wasserstrom, Yohannes Shiferaw, Rishi Arora
Abstract
Clinical trials of high-dose androgen therapy for prostate cancer have shown promising efficacy but are limited by lack of criteria to identify likely responders. To elucidate factors that govern the growth-repressive effects of high-dose androgens we applied an unbiased integrative approach utilizing genetic screens and transcriptional profiling of prostate cancer cells with or without demonstrated phenotypic sensitivity to androgen-mediated growth repression. Through this comprehensive analysis, we identified genetic events and related signaling networks that determine the response to both high-dose androgen and androgen withdrawal. We applied these findings to develop a gene signature that may serve as an early indicator of treatment response and identify men with tumors amenable to high dose androgen therapy.
Authors
Michael D. Nyquist, Alexandra Corella, Osama Mohamad, Ilsa Coleman, Arja Kaipainen, Daniel A. Kuppers, Jared M. Lucas, Patrick J. Paddison, Stephen R. Plymate, Peter S. Nelson, Elahe A. Mostaghel
