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.
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
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.
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
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.
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
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.
Timothy P. Fitzgibbons, Nancy Lee, Khanh-Van Tran, Sara Nicoloro, Mark Kelly, Stanley K.C. Tam, Michael P. Czech
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.
Selvi Celik, Mardjaneh Karbalaei Sadegh, Michael Morley, Carolina Roselli, Patrick T. Ellinor, Thomas Cappola, J. Gustav Smith, Olof Gidlof
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.
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
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.
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
Autoimmune diseases resulting from MHC class II-restricted autoantigen-specific T cell immunity include the systemic inflammatory autoimmune conditions, rheumatoid arthritis and vasculitis. While currently treated with broad-acting immunosuppressive drugs, a preferable strategy is to regulate antigen-specific effector T cells (Teff) to restore tolerance, by exploiting dendritic cell (DC) antigen presentation. We targeted draining lymph node (dLN) phagocytic DCs using liposomes encapsulating 1α,25-dihydroxyvitamin D3 (calcitriol) and antigenic peptide, to elucidate mechanisms of tolerance employed by DCs and responding T cells under resting and immunized conditions. PD-L1 expression was upregulated in dLN of immunized relative to naïve mice. Subcutaneous administration of liposomes encapsulating OVA323-339 and calcitriol targeted dLN PD-L1hi DCs of immunized mice and reduced their MHC class II expression. OVA323-339-calcitriol liposomes suppressed expansion, differentiation and function of Teff and induced Foxp3+ and IL-10+ peripheral (p)Treg in an antigen-specific manner, which was dependent on PD-L1. Peptide-calcitriol liposomes modulated CD40 expression by human DCs, and promoted Treg induction in vitro. Liposomes encapsulating calcitriol and disease-associated peptides suppressed the severity of rheumatoid arthritis and Goodpasture’s vasculitis models with suppression of antigen-specific memory T cell differentiation and function. Accordingly, peptide-calcitriol liposomes leverage DC PD-L1 for antigen-specific T cell regulation and induce antigen-specific tolerance in inflammatory autoimmune diseases.
Ryan Galea, Hendrik Nel, Meghna Talekar, Xiao Liu, Joshua D. Ooi, Megan Huynh, Sara Hadjigol, Kate J. Robson, Yi Tian Ting, Suzanne Cole, Karyn Cochlin, Shannon Hitchcock, Bijun Zeng, Suman Yekollu, Martine Boks, Natalie Goh, Helen Roberts, Jamie Rossjohn, Hugh H. Reid, Ben J. Boyd, Ravi Malaviya, David J. Shealy, Daniel G. Baker, Loui Madakamutil, A. Richard Kitching, Brendan J. O’Sullivan, Ranjeny Thomas
Nitric oxide (NO) regulates blood pressure (BP) by binding the reduced heme iron (Fe2+) in soluble guanylyl cyclase (sGC) and relaxing vascular smooth muscle cells (SMC). We previously showed that sGC heme iron reduction (Fe3+ → Fe2+) is modulated by cytochrome b5 reductase 3 (CYB5R3). However, the in vivo role of SMC CYB5R3 in BP regulation remains elusive. Here, we generated conditional smooth muscle cell-specific Cyb5r3 knockout mice (SMC CYB5R3 KO) to test if SMC CYB5R3 loss impacts systemic BP in normotension and hypertension via regulation of sGC redox state. SMC CYB5R3 KO mice exhibited a 5.84 mmHg increase in BP and impaired acetylcholine-induced vasodilation in mesenteric arteries compared to controls. To drive sGC oxidation and elevate BP, we infused mice with angiotensin-II. We found SMC CYB5R3 KO mice exhibited a 14.75 mmHg BP increase and mesenteric arteries had diminished NO-dependent vasodilation, but increased responsiveness to sGC heme-independent activator BAY 58-2667 over controls. Furthermore, acute injection of BAY 58-2667 in angiotensin-II treated SMC CYB5R3 KO mice showed greater BP reduction compared to controls. Together, these data provide the first in vivo evidence that SMC CYB5R3 is a sGC heme reductase in resistance arteries and provides resilience against systemic hypertension development.
Brittany G. Durgin, Scott A. Hahn, Heidi M. Schmidt, Megan P. Miller, Neha Hafeez, Ilka Mathar, Daniel Freitag, Peter Sandner, Adam C. Straub
We hypothesized that HIV-1 with dual-class but not single-class drug resistance mutations linked on the same viral genome, present in the virus population prior to initiation of antiretroviral therapy (ART), would be associated with failure of ART to suppress viremia. To test this hypothesis, we utilized an ultrasensitive single genome sequencing assay that detects rare HIV-1 variants with linked drug resistance mutations (DRMs). A case (ART failure) – control (non-failure) study was designed to assess whether linkage of DRMs in pre-ART plasma samples was associated with treatment outcome in the nevirapine /tenofovir/emtricitabine arm of the AIDS Clinical Trials Group A5208/OCTANE Trial 1 among women who had received prior single dose nevirapine. Ultrasensitive single genome sequencing revealed a significant association between pre-ART HIV variants with DRMs to 2 drug classes linked on the same genome (dual-class) and failure of three drug ART to suppress viremia. By contrast, linked, single-class DRMs were not associated with ART failure. We conclude that linked dual-class DRMs present before the initiation of ART are associated with ART failure, whereas linked single-class DRMs are not.
Valerie F. Boltz, Wei Shao, Michael J. Bale, Elias K. Halvas, Brian Luke, James A. McIntyre, Robert T. Schooley, Shahin Lockman, Judith S. Currier, Fred Sawe, Evelyn Hogg, Michael D. Hughes, Mary F. Kearney, John M. Coffin, John W. Mellors
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