Role Of Cardiac Macrophages In Inflammation And Tissue Repair In Cardiomyopath

Association between myocardial inflammation evaluated by 68GaDOTATATE PET/CT and clinical outcomes in cardiomyopathyBackgrounds:Macrophage infiltration in the myocardium has been confirmed in patients with cardiomyopathy,which affects the therapeutic efficacy and clinical prognosis of these patients.Therefore,imaging macrophage in the myocardium might be a potential clinical prognostic indicator in patients with cardiomyopathy.68Ga-DOTATATE has been proven to be a new inflammation marker with good macrophage specificity.We aimed to explore the prognostic value of myocardial 68Ga-DOTATATE uptake in cardiomyopathy.Methods:97 patients with cardiomyopathy were enrolled.The association between myocardial 68Ga-DOTATATE uptake and clinical outcomes was evaluated,including poor prognosis of left ventricular ejection fraction(LVEF)and heart failure rehospitalization.Results:Myocardial 68Ga-DOTATATE uptake was significantly higher in patients with poor prognosis of LVEF than in those without(mean SUVbw of LV:1.20[0.93,1.60]vs.0.96[0.78,1.20],p=0.0009;maximum SUVbw of LV:2.40[1.91,3.00]vs.1.84[1.44,2.25],p<0.0001;target to background ratio(TBR)mean of LV:2.79[2.46,3.33]vs.2.25[1.78,2.81],p=0.0007;TBRmax of LV:5.66[4.60,6.27]vs.4.02[3.09,5.90],p=0.0005).Myocardial 68Ga-DOTATATE uptake was also significantly higher in patients with heart failure rehospitalization than in those without(mean SUVbw of LV:1.22[0.95,2.06]vs.0.96[0.78,1.20],p=0.0003;maximum SUVbw of LV:2.33[1.92,3.71]vs.1.89[1.51,2.35],p=0.0012;TBRmean of LV:2.79[2.22,3.33]vs.2.40[1.83,2.89],p=0.0311),while no significant difference was found in TBRmax.In the multi-variable regression analysis,high myocardial 68Ga-DOTATATE uptake was identified as an independent predictor of poor prognosis of LVEF and heart failure rehospitalization.Conclusions:Myocardial 68Ga-DOTATATE uptake is strongly associated with adverse outcomes in cardiomyopathy,including poor prognosis of LVEF and heart failure rehospitalization.This finding may provide an important prognostic biomarker indicating chronically damaged myocardium with macrophage-driven inflammation.The role of decreased repair function mediated by M2-like macrophages in the progression mechanism of LVNC under stress.Backgrounds:Left ventricular non-compaction(LVNC)is the third most common type of congenital cardiomyopathy,which is caused by abnormal embryonic heart development due to intrauterine growth retardation in the first trimester of pregnancy(during normal myocardial compaction process).As the exact etiology and pathogenesis of LVNC are still unclear,there are currently no targeted treatment plans to reverse or delay disease progression.Gestational diabetes can lead to abnormal heart development in offspring,characterized by myocardial hypertrophy,non-compaction,and other features.Under various stress conditions,poorly developed myocardium is damaged and cannot perform normal function or even die,which may be one of the mechanisms of LVNC progression.Cardiac macrophages play a crucial role in cardiac inflammation,fibrosis,remodeling,and tissue repair.Exploring the abnormal quantity and function of M2-like macrophages is of great significance for exploring the mechanisms of LVNC progression under stress conditions,based on the repairing and protective effect of M2 on the injured myocardium.Methods:In this study,we used the STZ(Streptozotocin)-induced diabetic pregnant rat model to generate offspring with LVNC in the embryonic heart.We evaluated the development of the offspring’s hearts by pathological sectioning and HE staining,and assessed the proliferation activity and apoptosis/senescence-related protein(BAX,Bcl-2,P53,P21)expression of embryonic cardiomyocytes by MTT,TUNEL staining,RT-qPCR and other methods.We also evaluated the number and function of M2-like macrophages in embryonic heart by RT-qPCR(CD206,IL-10)and CD68+CD206 double fluorescence flow cytometry.In addition,we established an in vitro co-culture system of M2-like macrophages(extracted from rat peritoneal macrophages and stimulated with IL-4 for 48h)and H9C2 myocardial cells,and evaluated the repairing function of M2 on myocardial cell damage after 48h of hypoxia stimulation,in order to verify that the decrease of repair function mediated by M2-like macrophages in the heart leads to continuous injury of myocardial cells under hypoxic stress.To observe the changes in signal transduction pathways involved in the co-culture system,we carried out transcriptome sequencing(RNA-seq)analysis on total RNA extracted from H9C2 myocardial cells in the hypoxia control group and the hypoxia+M2 co-culture group.Results:1.Compared with the control group,the blood glucose of STZ-induced gestational diabetes rats was significantly increased.The non-compaction/compacted layer(NC/C)of the embryonic myocardium in the STZ group was significantly higher than that in the control group,with a proportion of 77.0%of fetal heart NC/C>1.4,indicating that high glucose-induced by STZ leads to poor fetal heart development and the presence of LVNC.2.Compared with the control group,the number of cells with CD68+CD206 positive in the embryonic heart of the STZ-induced gestational diabetes group was significantly reduced.By RT-qPCR,the expression levels of CD206 and IL-10 in the STZ group were significantly lower than those in the control group,indicating a significant reduction in the number and function of M2-like macrophages in the embryonic heart of the STZ-induced gestational diabetes group.3.Using the MTT assay,it was found that the proliferation activity of primary embryonic cardiomyocytes in the STZ group was significantly decreased compared with the control group.In addition,the apoptosis index detected by TUNEL staining in the STZ-induced gestational diabetes group was significantly increased compared with the normal control group.According to qPCR results of primary myocardial cells,the mRNA expression levels of the pro-apoptotic factor BAX and the cell senescence-related protein P53 and P21 in the STZ-induced gestational diabetes group were significantly increased compared with those in the control group,while the mRNA expression level of the pro-survival factor Bcl-2 was significantly reduced,indicating a decrease in the proliferation activity of cardiomyocyte in the STZ group and an increase in the expression levels of apoptosis/senescence-related signaling pathways.4.In the co-culture system of M2 and H9C2 cardiomyocyte,it was found that under hypoxic conditions,the activity of H9C2 cardiomyocyte was significantly reduced compared with normal oxygen conditions,while the co-culture with M2-like macrophages under hypoxic conditions significantly increased cell proliferation activity.In addition,the mRNA expression levels of the pro-apoptotic factor BAX and the cell senescence related protein P53 and P21 were significantly increased under hypoxic conditions compared with normal oxygen conditions,while the mRNA expression level of the pro-survival factor Bcl-2 was significantly reduced.In the hypoxia+M2 co-culture group,the mRNA expression levels of BAX and P53 were significantly decreased compared with the hypoxia control group,and the expression levels of Bcl-2 and P21 showed a trend of change,but the difference was not statistically significant.The levels of cTnI and CKMB were significantly increased under hypoxic conditions compared with normal oxygen conditions,while the levels of cTnI and CKMB in hypoxia+M2 co-culture group were significantly decreased compared with the hypoxia control group.The transcriptome sequencing results showed that compared with the hypoxia control group,there were 1193 up-regulated and 392 down-regulated differential gene expressions in the hypoxia+M2 co-culture group.GO and KEGG enrichment analysis confirmed the biological functions and pathways related to cardiomyopathy and cardiomyocyte injury.Conclusion:In summary,the present study provides important insights into the mechanisms underlying LVNC progression.The findings suggest that high glucoseinduced by STZ leads to poor fetal heart development and the presence of LVNC.The decrease in the number and function of M2-like macrophages in the embryonic heart may contribute to LVNC progression under stress conditions,resulting in impaired function or even cell death.The repairing and protective effect of M2-like macrophages on injured myocardium suggests that therapies targeting these cells could be potential treatments for LVNC.The results of this study could contribute to the development of new therapeutic strategies for LVNC and improve the understanding of its pathogenesis.