Hepatocyte-derived MANF is protective for rifampicin-induced cholestatic hepatic injury via inhibiting ATF4-CHOP signal activation.

Rifampicin (RFP) has been known to be potentially hepatotoxic and often used as an inducer of cholestatic hepatic injury. Here we found that mesencephalic astrocyte-derived neurotrophic factor (MANF), an endoplasmic reticulum (ER) stress inducible protein, is a protector in RFP-induced liver injury. In cholestatic hepatic injury mice induced by RFP, the liver/body ratio and the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bile acid (TBA), total bilirubin (TBIL), and direct bilirubin (DBIL) were significantly increased. Meanwhile, the protein and mRNA levels of MANF were remarkably elevated in the liver injury mice. In hepatocyte-specific MANF knockout (HKO) mice, an extra increase in the liver/body ratio and serum ALT, AST, ALP, TBA, TBIL, and DBIL levels was detected after treatment with RFP. In addition, recombinant human MANF (rhMANF) treatment efficiently reduced the liver/body ratio and serum ALT, AST, ALP, TBA, TBIL, and DBIL levels in RFP-induced liver injury mice. Furthermore, we found there is an increase in the number of the apoptotic cells, detected by TUNEL staining in the liver tissues of HKO mice. Meanwhile, the protein levels of C/EBP-homologous protein (CHOP), Ki67, and the proliferating cell nuclear antigen (PCNA), as well as the mRNA level of Ki67 were elevated after treated with RFP, and these parameters were increased more significantly in HKO mice than that in wild type (WT) controls in RFP-induced liver injury. The rhMANF treatment can rescue the cell apoptosis and reduce the protein and mRNA levels of CHOP, Ki67, and PCNA elevated by MANF deletion and RFP. In HKO mice, immunoglobulin heavy chain binding protein (BIP) and activating transcription factor 4 (ATF4) were predominantly increased after treatment with RFP, which were reduced by rhMANF treatment. Therefore, we conclude that hepatocyte-derived MANF is protective for RFP-induced cholestatic hepatic injury via inhibiting ATF4-CHOP signal activation and subsequent cell apoptosis.