The LPS induced pyroptosis exacerbates BMPR2 signaling deficiency to potentiate SLE-PAH

Pulmonary arterial hypertension (PAH) is a common and fatal complication of systemic lupus erythematosus (SLE). Whether the BMP receptor deficiency found in the genetic form of PAH is also involved in SLE-PAH patients remains to be identified. In this study, we employed patient-derived samples from SLE-associated PAH (SLE-PAH) and established comparable mouse models to clarify the role of BMP signaling in the pathobiology of SLE-PAH. Firstly, serum levels of LPS and autoantibodies (auto-Abs) directed at BMP receptors were significantly increased in patients with SLE-PAH compared with control subjects, measured by ELISA. Mass cytometry was applied to compare peripheral blood leukocyte phenotype in patients prior to and after treatment with steroids, which demonstrated inflammatory cells alteration in SLE-PAH. Furthermore, BMPR2 signaling and pyroptotic factors were examined in human pulmonary arterial endothelial cells (PAECs) in response to LPS stimulation. Interleukin-8 (IL-8) and E-selectin (SELE) expressions were up-regulated in autologous BMPR2^+/R899X endothelial cells and siBMPR2-interfered PAECs. A SLE-PH model was established in mice induced with pristane and hypoxia. Moreover, the combination of endothelial specific BMPR2 knockout in SLE mice exacerbated pulmonary hypertension. Pyroptotic factors including gasdermin D (GSDMD) were elevated in the lungs of SLE-PH mice, and the pyroptotic effects of serum samples isolated from SLE-PAH patients on PAECs were analyzed. BMPR2 signaling upregulator (BUR1) showed anti-pyroptotic effects in SLE-PH mice and PAECs. Our results implied that deficiencies of BMPR2 signaling and proinflammatory factors together contribute to the development of PAH in SLE.