Targeted inhibition of PTPN22 is a novel approach to alleviate osteogenic responses in aortic valve interstitial cells and aortic valve lesions in mice.

backgroundCalcific aortic valve disease (CAVD) is the most prevalent valvular disease and has high morbidity and mortality. CAVD is characterized by complex pathophysiological processes, including inflammation-induced osteoblastic differentiation in aortic valve interstitial cells (AVICs). Novel anti-CAVD agents are urgently needed. Protein tyrosine phosphatase nonreceptor type 22 (PTPN22), an intracellular nonreceptor-like protein tyrosine phosphatase, is involved in several chronic inflammatory diseases, including rheumatoid arthritis and diabetes. However, it is unclear whether PTPN22 is involved in the pathogenesis of CAVD.

methodsWe obtained the aortic valve tissue from human and cultured AVICs from aortic valve. We established CAVD mice model by wire injury. Transcriptome sequencing, western bolt, qPCR, and immunofluorescence were performed to elucidate the molecular mechanisms.

resultsHere, we determined that PTPN22 expression was upregulated in calcific aortic valve tissue, AVICs treated with osteogenic medium, and a mouse model of CAVD. In vitro, overexpression of PTPN22 induced osteogenic responses, whereas siRNA-mediated PTPN22 knockdown abolished osteogenic responses and mitochondrial stress in the presence of osteogenic medium. In vivo, PTPN22 ablation ameliorated aortic valve lesions in a wire injury-induced CAVD mouse model, validating the pathogenic role of PTPN22 in CAVD. Additionally, we discovered a novel compound, 13-hydroxypiericidin A 10-O-α-D-glucose (1 → 6)-β-D-glucoside (S18), in a marine-derived Streptomyces strain that bound to PTPN22 with high affinity and acted as a novel inhibitor. Incubation with S18 suppressed osteogenic responses and mitochondrial stress in human AVICs induced by osteogenic medium. In mice with aortic valve injury, S18 administration markedly alleviated aortic valve lesions.

conclusionPTPN22 plays an essential role in the progression of CAVD, and inhibition of PTPN22 with S18 is a novel option for the further development of potent anti-CAVD drugs. Therapeutic inhibition of PTPN22 retards aortic valve calcification through modulating mitochondrial dysfunction in AVICs.