Inhibition Of B Cell Function By Rituximab Prevents And Reverses Pressure Overload-induced Cardiac Remodeling In Mice

Background:Cardiac remodeling is a main risk factor for heat failure(HF)and death.B lymphocytes have been shown to contribute to autoimmune diseases via producing antibodies and proinflammatory cytokines.Clinical studies show that removal of IgG3 by immunosorbent therapy improves cardiac hypertrophy.Depletion of B cells by CD20 neutralizing antibody inhibit angiotensin II(Ang II)-induced inflammation and cardiac remodeling;however,the role of B lymphocytes in cardiac remodeling and HF induced by pressure overload remains unclear.Objective:The present study aimed to examine the role of B lymphocytes in pressure overload-induced cardiac remodeling in mice with CD20 neutralizing antibody(also known Rituximab,RTX),used clinically in oncology,elucidate the underlying mechanism,and test whether Rituximab represents a potential therapeutic drug for treating HF.Methods:Cardiac remodeling was established by pressure overload induced by transverse aortic constriction(TAC).Wild-type(WT)male C57BL/6J mice(weight22-25g)were randomly divided into four groups:Sham,Sham+Rituximab,TAC,TAC+Rituximab.Echocardiography was used to evaluate cardiac systolic function.Analysis of pressure-volume relationship shown systolic and diastolic function of heart.Flow cytometery was used to examine the amount of CD45~+cells,B lymphocytes,T lymphocytes,macrophages and neutrophils in the heart.Western blot analysis was used to quantify protein involved in hypertrophy,fibrosis and inflammation signals.Real-Time PCR was used to test mRNA levels.ELISA assay was conducted to measure levels of IgG,IgA and IgM in the heart and serum.The weight of hearts were corrected by heart weight to body weight(HW/BW)and heart weight to tibia length(HW/TL);WGA staining was used to analyze the cross-sectional area of cardiomyocytes.Masson’s trichrome staining was used to analyze fibrosis.Results:(1)Compared with Ig control,administration of Rituximab significantly improves cardiac systolic and diastolic dysfunction in vivo;(2)Rituximab treatment markedly suppressed TAC-induced cardiac hypertrophy(reduced heart size,left ventricular chamber dilation,HW/BW and HW/TL ratios,cross-sectional area of myocytes and the expression of ANP and BNP);(3)Rituximab treatment remarkably attenuated TAC-induced cardiac fibrosis(decrease of collagen deposition and the expression of collagen I and III)and oxidative stress(reduction the expression level of NOX2 and NOX4);(4)Rituximab treatment markedly inhibited TAC-induced activation of inflammatory signaling(IKK/NF-κB),hypertrophic signaling(Calcineurin A,STAT3 and ERK1/2)and fibrotic signaling(TGF-β/Smad2/3)as well as the levels of proinflammatory cytokines(IL-6,IL-1β,TNF-α).Conclusions:The present study identifies that Rituximab can inhibit pressure overload-induced cardiac remodeling and dysfunction in mice.The beneficial effect is associated with inhibition of B cells,which results in reduction of IgG and proinflammatory cytokines leading to attenuation of hypertrophic and fibrotic signaling pathways.These data suggest that Rituximab may be a promising drug for treating hypertrophic disease and HF.