NLRP3 inflammasome inhibition decreases <i>Schistosomiasis japonica</i> -induced granulomatous inflammation and fibrosis in BALB/c mice

To research the role of the NLRP3 inflammasome in <i>Schistosoma japonicum</i>-induced granuloma formation and liver fibrosis. In <i>in vivo</i> tests, BALB/c mice were used. shNLRP3 plasmid based on adeno-associated virus serotype 8 (AAV8-shNLRP3) was injected to block NLRP3 inflammasome via tail vein. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected to assess liver injury. H&E staining was used for routine histopathological assessment; Masson's trichrome staining was used to detect fibrous tissues and collagen fibers. Hepatic expression of NLRP3, procaspase-1, bioactive caspase-1, collagen-1, tissue inhibitor of metalloproteinases-1 (TIMP-1), and α-smooth muscle actin (α-SMA) were detected by western blot. Serum levels of IL-1β were detected by enzyme-linked immunosorbent assay (ELISA). The inflammatory cell infiltration and hepatic expression of IL-1β around the granuloma were detected by immunohistochemistry staining. Treatment of <i>S. japonicum</i> infected mice with AAV8-shNLRP3 significantly reduced the hepatic levels of bioactive caspase-1 and IL-1β, as well as circulating IL-1β concentrations, while reducing the amounts of myeloperoxidase (MPO) and F4/80 positive cells around the granuloma. Moreover, collagen deposition, TIMP-1, and α-SMA, which are markers of hepatic stellate cell (HSC) activation, were reduced around the liver granuloma. These findings highlight a therapeutic potential of AAV8-shNLRP3 in schistosomiasis cirrhosis.