B cell-derived anti-beta 2 glycoprotein I antibody mediates hyperhomocysteinemia-aggravated hypertensive glomerular lesions by triggering ferroptosis

Hyperhomocysteinemia(HHcy)is a risk factor for chronic kidney diseases(CKDs)that affects about 85%CKD patients.HHcy stimulates B cells to secrete pathological antibodies,although it is unknown whether this pathway mediates kidney injury.In HHcytreated 2-kidney,1-clip(2K1C)hypertensive murine model,HHcy-activated B cells secreted anti-beta 2 glycoprotein I(β2GPI)antibodies that deposited in glomerular endothelial cells(GECs),exacerbating glomerulosclerosis and reducing renal function.Mechanistically,HHcy 2K1C mice increased phosphatidylethanolamine(PE)(18:0/20:4,18:0/22:6,16:0/20:4)in kidney tissue,as determined by lipidomics.GECs oxidative lipidomics validated the increase of oxidized phospholipids upon Hcy-activated B cells culture medium(Hcy-B CM)treatment,including PE(18:0/20:4+3[O],PE(18:0a/22:4+1[O],PE(18:0/22:4+2[O]and PE(18:0/22:4+3[O]).PE synthases ethanolamine kinase 2(etnk2)and ethanolamine-phosphate cytidylyltransferase 2(pcyt2)were increased in the kidney GECs of HHcy 2K1C mice and facilitated polyunsaturated PE synthesis to act as lipid peroxidation substrates.In HHcy 2K1C mice and Hcy-B CM-treated GECs,the oxidative environment induced by iron accumulation and the insufficient clearance of lipid peroxides caused by transferrin receptor(TFR)elevation and down-regulation of SLC7A11/glutathione peroxidase 4(GPX4)contributed to GECs ferroptosis of the kidneys.In vivo,pharmacological depletion of B cells or inhibition of ferroptosis mitigated the HHcy-aggravated hypertensive renal injury.Consequently,our findings uncovered a novel mechanism by which B cell-derived pathogenic anti-β2GPI IgG generated by HHcy exacerbated hypertensive kidney damage by inducing GECs ferroptosis.Targeting B cells or ferroptosis may be viable therapeutic strategies for ameliorating lipid peroxidative renal injury in HHcy patients with hypertensive nephropathy.

Single-cell RNA sequencing reveals B cell-T cell interactions in vascular adventitia of hyperhomocysteinemia-accelerated atherosclerosis

Dear Editor Cardiovascular disease(CVD)is the leading cause of death around the world(Truelsen,et al.,2015).Atherosclerosis,the dominant underlying cause of CVD,is a chronic inflam-matory disease characterized by lipid accumulation and immune cell infiltration in plaques and vessels(Weber,et al.,1950).The immune microenvironment is critical for the development of atherosclerosis.Homocysteine(Hcy)is an intermediate product of methionine metabolism,and its ele-vation in plasma(>15μmol/L),known as hyperhomocys-teinemia(HHcy),is an independent risk factor for atherosclerosis.HHcy is more common in Asia because of genetic factors and dietary habits(Huo,et al.,2015).folic acid supplement is one of the most important way to treat HHcy in clinic.Although HHcy potentiates atherosclerosis mainly through endothelial injury and inflammatory activa-tion(Luo,et al.,2016),a comprehensive understanding of the immune microenvironment and potential mechanisms in HHcy-accelerated atherosclerotic aortas(HHcy-AA)is still lacking.