Background Despite the increasing prevalence of heart failure (HF) with preserved ejection fraction (HFpEF) in humans, there remains no therapeutic options for HFpEF. Adiponectin (APN), an adipocyte-derived cytokine exerts cardioprotective actions and its deficiency is implicated in the development of hypertension and HF with reduced ejection fraction. Similarly APN deficiency in HFpEF exacerbates left ventricular hypertrophy (LVH), diastolic dysfunction and HF. However, the therapeutic effects of APN in HFpEF remain unknown. We sought to test the hypothesis that chronic APN overexpression protects against the progression of HF in a murine model of HFpEF. Methods and Results APN transgenic (APNTG) and wild-type (WT) mice underwent uninephrectomy, a continuous saline or d-aldosterone infusion and given 1.0% sodium chloride drinking water for 4-weeks. Aldosterone-infused WT mice developed HFpEF with hypertension, LVH and diastolic dysfunction. Aldosterone infusion increased myocardial oxidative stress and decreased sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) protein expression in HFpEF. Although total phospholamban (PLN) protein expression was unchanged, there was decreased expression of PKA-dependent PLN phosphorylation at Ser16 and CaMKII-dependent PLN phosphorylation at Thr17. APN overexpression in aldosterone-infused mice ameliorated LVH, diastolic dysfunction, lung congestion and myocardial oxidative stress without affecting blood pressure (BP) and LVEF. This improvement in diastolic function parameters in aldosterone-infused APNTG mice was accompanied by preserved protein expression of PKA-dependent phosphorylation of PLN at Ser16. APN replacement prevented the progression of aldosterone-induced HFpEF, independent of BP, by improving diastolic dysfunction and modulating cardiac hypertrophy. Conclusions These findings suggest that APN may have therapeutic effects in patients with HFpEF.
In obesity, IL-13 overcomes insulin resistance by promoting anti-inflammatory macrophage differentiation in adipose tissue. Endogenous IL-13 levels can be modulated by the IL-13 decoy receptor, IL-13Rα2, which inactivates and depletes the cytokine. In this study, we show that IL-13Rα2 is markedly elevated in adipose tissues of obese mice. Mice deficient in IL-13Rα2 had high expression of IL-13 response markers in adipose tissue, consistent with increased IL-13 activity at baseline. Moreover, exposure to the type 2 cytokine-inducing alarmin, IL-33, enhanced serum and tissue IL-13 concentrations and elevated tissue eosinophils, macrophages, and type 2 innate lymphoid cells. IL-33 also reduced body weight, fat mass, and fasting blood glucose levels. Strikingly, however, the IL-33-induced protection was greater in IL-13Rα2-deficient mice compared with wild-type littermates, and these changes were largely attenuated in mice lacking IL-13. Although IL-33 administration improved the metabolic profile in the context of a high fat diet, it also resulted in diarrhea and perianal irritation, which was enhanced in the IL-13Rα2-deficient mice. Weight loss in this group was associated with reduced food intake, which was likely related to the gastrointestinal effects. These findings outline both potentially advantageous and deleterious effects of a type 2-skewed immune response under conditions of metabolic stress, and identify IL-13Rα2 as a critical checkpoint in adipose tissues that limits the protective effects of the IL-33/IL-13 axis in obesity.
BackgroundRheumatoid arthritis (RA) is a common autoimmune disease characterized by chronic inflammation of the joints, leading to bone erosion and joint dysfunction. Despite the recent successes of disease-modifying anti-rheumatic drugs (DMARDs), there is still clinical need for understanding the development and molecular etiology of RA. Wnts are developmental morphogens whose roles in adult pathology are poorly characterized. Wnt5a is a member of the non-canonical family of Wnts that modulates a wide range of cell processes, including differentiation, migration, and inflammation. Wnt5a has been implicated as a possible contributor to arthritis and it is upregulated in synovial fibroblasts from RA patients.MethodsWe investigated the role of endogenous Wnt5a in RA. Tamoxifen-inducible, Wnt5a knockout (Wnt5a cKO) mice and littermate controls were monitored for arthritis development and joint pathology using the K/BxN serum transfer-induced arthritis (STIA) model. To explore a role of Wnt5a in osteoclast fusion, bone marrow-derived monocytes (BMDMs) were differentiated in vitro.ResultsWnt5a cKO mice were resistant to arthritis development compared to control littermates as assessed by ankle thickness and histologic measurements. Some parameters of inflammation were reduced in the Wnt5a cKO mice, including the extent of polymononuclear cell infiltration and extra-articular inflammation. Wnt5a cKO mice also exhibited less cartilage destruction and a reduction in osteoclast activity with concomitant reduction in tartrate-resistant acid phosphatase (TRAP), cathepsin K (CTSK), macrophage colony-stimulating factor (MCSF), matrix metalloproteinase (MMP)2 and MMP9 in the arthritic joints. Treatment of BMDMs with Wnt5a enhanced osteoclast fusion and increased the expression of dendrocyte-expressed seven transmembrane protein (DCSTAMP) and MMP9, that are necessary for osteoclast formation and activity.ConclusionsThese data suggest that Wnt5a modulates the development of arthritis by promoting inflammation and osteoclast fusion, and provide the first mouse genetic evidence of a role for endogenous Wnt5a in autoimmune disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-017-1375-0) contains supplementary material, which is available to authorized users.
BackgroundThe insulin/insulin‐like growth factor/relaxin family represents a group of structurally related but functionally diverse proteins. The family member relaxin‐2 has been evaluated in clinical trials for its efficacy in the treatment of acute heart failure. In this study, we assessed the role of insulin‐like peptide 6 (INSL6), another member of this protein family, in murine heart failure models using genetic loss‐of‐function and protein delivery methods.Methods and ResultsInsl6‐deficient and wild‐type (C57BL/6N) mice were administered angiotensin II or isoproterenol via continuous infusion with an osmotic pump or via intraperitoneal injection once a day, respectively, for 2 weeks. In both models, Insl6‐knockout mice exhibited greater cardiac systolic dysfunction and left ventricular dilatation. Cardiac dysfunction in the Insl6‐knockout mice was associated with more extensive cardiac fibrosis and greater expression of fibrosis‐associated genes. The continuous infusion of chemically synthesized INSL6 significantly attenuated left ventricular systolic dysfunction and cardiac fibrosis induced by isoproterenol infusion. Gene expression profiling suggests liver X receptor/retinoid X receptor signaling is activated in the isoproterenol‐challenged hearts treated with INSL6 protein.ConclusionsEndogenous Insl6 protein inhibits cardiac systolic dysfunction and cardiac fibrosis in angiotensin II– and isoproterenol‐induced cardiac stress models. The administration of recombinant INSL6 protein could have utility for the treatment of heart failure and cardiac fibrosis.
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