Time profiles of the expression of metalloproteinases, tissue inhibitors of metalloproteases, cytokines and collagens in hamsters infected with Opisthorchis viverrini with special reference to peribiliary fibrosis and liver injury

Abstract

The liver fluke Opisthorchis viverrini is endemic in southeastern Asia, and causes cholangiocarcinoma and liver fibrosis. We investigated the time profile of the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) in relation to peribiliary fibrosis in O. viverrini-infected hamsters. Hepatic mRNA expression of MMPs, TIMPs, cytokines and collagens I and III was assessed by quantitative reverse transcription-PCR. Zymography and immunohistochemistry were also used to examine MMPs-2 and -9 expression. After infection, an increase of peribiliary fibrosis was time-dependent. Opisthorhis viverrini-induced gene expression in hamster liver, with increased mRNA expression levels of IL-1β, TNF-α, TGF-β, and collagens I and III, was observed at 21 days p.i. Expression of MMPs-2, -13 and -14 and TIMPs-1 and -3 genes, was significantly higher at 1 month, and maximal levels of most MMPs (MMPs-2, -9, -13 and -14) were observed at 2 months p.i. The cytoplasmic levels of MMP-2 and MMP-9 were similar to mRNA expression. Immunohistochemistry revealed that MMP-9 was expressed mainly in the cytoplasm of inflammatory cells at the invasive front of the fibrous area. In contrast, the highest levels of mRNA expression of TIMPs-2 and -3, and TGF-β were observed 10 months p.i. Concentration of TIMP-2 protein in the plasma correlated with its transcriptional level ( r = 0.320, P = 0.040). Peribiliary fibrosis correlated positively with liver hydroxyproline content ( r = 0.846, P < 0.001), plasma hydroxyproline concentration ( r = 0.770, P < 0.001), plasma TIMP-2 level ( r = 0.335, P = 0.046), and mRNA expression levels of MMP-7 ( r = 0.511, P = 0.006), TIMP-1 ( r = 0.320, P = 0.040), TIMP-2 ( r = 0.428, P = 0.026), and TIMP-3 ( r = 0.553, P = 0.003). This study suggests that expression of MMPs is associated with an inflammatory reaction in the early phase and TIMPs expression at the late phase may contribute to both fibrosis and liver injury. MMPs and TIMPs may serve as diagnostic markers for the severity of O. viverrini-induced liver injury.