The Mechanistic Study Of TET2 Inhibited Macrophage Polarization In Pulmonary Hypertension

Pulmonary hypertension（PH）is a type of cardiovascular and pulmonary diseases with complex causes.Its main clinical feature is the progressive increase of pulmonary vascular resistance,which can lead to severe consequences,such as limitation of exercise,heart failure and even death.Pulmonary artery remodeling,characterized by abnormal muscularisation of small pulmonary arteries,thickened intima and media,is the main pathological mechanism of pulmonary hypertension.In contrast,macrophages have been shown to regulate the proliferative function of smooth muscle cells through the secretion of inflammatory cytokines,thus participating into the pathological process of vascular remodeling.Ten Eleven Translocation methylcytosine dioxygenase 2（TET2）,a member of the TET family,has been shown to regulate macrophage function in inflammatory diseases through various pathways such as regulation of histone deacetylation and production of inflammatory vesicles.However,the mechanism of TET2 action on macrophages in pulmonary hypertension remains unclear.【Objective】To investigate the role of TET2 in regulating the inflammatory process of macrophages in pulmonary arterial hypertension and the mechanism of TET2 in pulmonary arterial hypertension.【Methods】1.Using C57/BL6 mice with myeloid-specific knockout Tet2 mice to induce PH model.Right ventricular systolic pressure（RVSP）measured by right heart catheter through the jugular vein was used to determine the effect of modeling.2.The changes of macrophage function and Tet2 expression level were observed in the pathological conditions of pulmonary hypertension using ELISA and immunofluorescence techniques.3.To study the changes of macrophage function by flow cytometry and immunofluorescence and RT-q PCR.4.To study the proliferation of smooth muscle using techniques such as cell proliferation assay（Bucculit Fd U Cu-Free Cell Proliferation Fluorescence Imaging Kit,Brd U）and CCK8（Cell counting kit 8）.Thus,the possible mechanisms by which macrophages affect smooth muscle were investigated.【Results】.In the situation of pulmonary hypertension,the level of IL-1βwere significantly increased in mice,Tet2 expression was decreased in lung,and a significant increase in the number of interstitial lung macrophages and the tendency of macrophage to polarize toward M1-type macrophages was also significantly higher than the normoxic group.2.After in vivo induction of pulmonary hypertension model,right ventricular systolic pressure was higher and vascular medial hypertrophy was more pronounced in the LYZ-2Cre⁺Tet2 ^f/f group compared to the LYZ-2Cre^-Tet2^f/fgroup of mice.3.In vitro hypoxic model to simulated pulmonary hypertension,the BMDM of mice in the LYZ-2Cre⁺Tet2 ^f/f group showed a more pronounced trend of macrophage polarization to M1 type and increased IL-1βsecretion compared with mice in the LYZ-2Cre^-Tet2^f/fgroup.4.Compared with the normoxic environment,the proliferation of mouse pulmonary artery smooth muscle cells（m PASMC）was stimulated by bone marrow-derived macrophages（BMDM）culture supernatants obtained under hypoxic environment 5.5.Anakinra,an inhibitor of IL-1βreceptor,inhibited the proliferation of BMDM culture supernatant-stimulated pulmonary artery smooth muscle cells.6.The expression of IL-1R1 and MYD88 in small arterial vascular smooth muscle cells in lung tissue of LYZ-2Cre⁺Tet2 ^f/fgroup mice was significantly higher than that in LYZ-2Cre^-Tet2^f/fgroup.【Conclusions】The decrease of TET2 in myeloid cells may be involved in the formation of pulmonary hypertension by promoting M1 polarization of macrophages,leading to increased secretion of the inflammatory factor IL-1β,and by upregulating IL1-R1 and My D88 in smooth muscle cells,promoting excessive proliferation of smooth muscle cells.