Role of Interleukin 17A in Aortic Valve Inflammation in Apolipoprotein E-deficient Mice

IL-17A induces valvular endothelial inflammation and aggravates calcific aortic valve disease

Calcific aortic valve disease (CAVD) is an aging related disease characterized by inflammation and fibrocalcific remodeling. IL-17A is a key cytokine associated with pathophysiology of inflammatory and fibrotic disease. Previous studies showed accumulation of IL-17A-producing T helper lymphocytes in human calcified aortic valves and significantly elevated IL-17RA expression in calcified valves. However, the role of IL-17A signaling in the initiation and development of CAVD is still unclear. In this study, by analyzing public transcriptome databases, we found that IL-17A-IL-17RA signaling is activated in calcified valves. Gene expression analysis revealed significantly increased IL-17A, IL-17RA, and RUNX2 expression in calcified human aortic valves compared to in non-calcified valves, and the expression of IL-17A and IL-17RA were positively correlated with RUNX2 expression. A 5/6 nephrectomy was performed in Apoe^-/- (Apoe knockout) mice to establish a CAVD mouse model. IL-17A-neutralizing antibodies significantly reduced valve calcium deposition and decreased expression of RUNX2 in aortic valves. Immunofluorescence staining of human aortic valves and qRT-PCR analysis of primary aortic valve cells revealed abundant expression of IL-17RA in valvular endothelial cells (VECs). RNA sequencing indicated that IL-17A promoted the activation of inflammatory signaling pathways in VECs. Furthermore, qRT-PCR and cytometric bead array analysis confirmed that IL-17A promoted the expression or secretion of inflammatory cytokines IL-6 and IL-1β, chemokines CXCL2 and CXCL8, and fibrosis-related gene COL16A1. Our findings indicate that elevated IL-17A in CAVD may promote valve inflammation, fibrosis, and calcification by inducing endothelial activation and inflammation. Targeting IL-17A-IL-17RA signaling may be a potential therapeutic strategy for CAVD.

MicroRNA-29b regulates pyroptosis involving calcific aortic valve disease through the STAT3/SOCS1 pathway

BACKGROUND

CAVD (calcific aortic valve disease) involves an inflammatory response similar to pyroptosis; therefore, we speculated that the progression of pyroptosis might be involved in the pathogenesis of CAVD.

METHODS

We first investigated the expression of pyroptosis related genes in human CAVD, non-CAVD control and AS (calcific aortic stenosis) tissues. We further confirmed these genes by using CAVD cell and mouse models. Finally, we explored the functional molecular mechanism in the cell model.

RESULTS

Our recent studies found that miR-29b plays an important role in CAVD, and we wanted to further address whether miR-29b is a key factor in the progression of pyroptosis related to CAVD. In this study, we found NLRP3 was highly expressed in CAVD patients and models. In contrast, SOCS1, a suppressor of NLRP3, showed reduced expression in CAVD. Furthermore, we found that ASC, Caspase-1, IL-1β, Cleaved IL-18 and p-JAK2 were all upregulated in the tissues of CAVD patients, suggesting the likelihood of activation of the inflammasome. Then, we found that miR-29b participated in the NLRP3-regulated CAVD pathway through its target gene STAT3 (signal transducer and activator of transcription 3). Finally, we found that a miR-29b inhibitor could mitigate the increases in osteogenic differentiation and pyroptosis and that SOCS1 showed negative regulation of osteogenic differentiation and pyroptosis in CAVD.

CONCLUSION

These findings suggested NLRP3 inflammasome-related genes are highly expressed in CAVD, and miR-29b reverses osteoblastic differentiation of aortic valve interstitial cells by regulating pyroptosis and inhibiting inflammation via the STAT3/SOCS1 pathway.