Preliminary Study On Vasculitis Susceptibility In WKY Rats Stimulated By Immune Activation By Silica Combined With NETs

Objective:This study aims to explore whether repeated immune stimulation of NETs in the context of silica exposure can cause immune activation and induce the production of MPO-ANCA in rats,and further reveal the causal relationship between silica exposure and AAVMethods:A rat model of silicon exposure was established by intratracheal instillation of silicon dioxide suspension.NETs combined with Freund’s adjuvant were used to stimulate silicon exposed rats repeatedly.The rats were divided into normal control group(N,n=5),control+NETs group(N+NETs,n=5),silicon exposed group(S,n=5)and silicon exposed+NETs group(S+NETs,n=6).Renal function was measured in 4 groups,and pathological changes of lung and kidney were observed,serum myeloperoxidase ANCA,serum citrullinated histone H3(CitH3),serum tumor necrosis factor(TNF-α)and inflammatory cytokine interleukin-17(IL-17A)were detected by ELISA.The expression and localization of NETs in lung and kidney were observed by immunofluorescence staining and laser confocal microscopy.Results:(1)He staining sections of rats showed that the lung tissue of the S+NETS group showed alveolar wall thickening and inflammatory cell infiltration,and a large number of granulocytes and erythrocytes exudated in the alveolar cavity,suggesting alveolar hemorrhage.Group S showed characteristic infiltration of macrophages and neutrophils without pulmonary hemorrhage.No abnormalities were observed in the lung tissues of the N and N+NETs groups.In the S+NETS group,there was a small amount of inflammatory cell infiltration in glomeruli and renal tubules,and local congestion in renal medulla.No obvious abnormalities were observed in the kidney tissues of the S group,N+NETs group and N group.(2)The double immunofluorescence staining of NETs components including CitH3 and MPO in lung tissues of S+NETs group was significantly stronger than those in other three groups.(3)The serum levels of CitH3,IL-17A and TNF-α in the S+NETs group were significantly higher than those in other three groups(P<0.05).Although there was no significant difference in MPO-ANCA,the MPO-ANCA has shown an increasing trend in S+NETs group.(4)Pearson correlation analysis showed that serum IL-17A,CitH3 and TNF-αshowed a significant positive correlation(r>0.6,P<0.05).Conclusions:Silica exposure induces a state of immune microenvironment in rats.Repeated stimulation by NETs can activate immune inflammatory response and produce a variety of cytokines,which are involved in the body’s immune response.It provides evidence clues for exploring the relationship between silicon exposure and AAV in the future.