Objective To study the expression and transcription of complement regulatory protein CD46 in immune liver injury of trichlorethylene (TCE) sensitized mice exacerbated by poly I:C.
Methods Thirty-six female BALB/c mice (6-8 weeks old) were randomly divided into blank control group (n=4), solvent control group (n=4), TCE treatment group (n=15), and TCE+poly I:C treatment group (n=13).Sensitization treatment was administered on day 1, 4, 7, and 10 after adaptive feeding for one week, and challenge on day 17 and 19.The mice in the TCE+poly I:C treatment group were given intraperitoneal injection of 50μg poly I:C at 3 h before last challenge treatment.Mice skin reactions were observed and scored at 24 h after the last challenge.ALT and AST were detected by commercial kit from serund liver samples at 48 h after challenge.Histological damage of liver was observed by HE staining.Expressions of CD46 and C3 fragment were observed by immunohistochemistry.mRNA expressions of CD46 were detected by RT-PCR.
Results There was no skin erythema or edema in the blank control group and the solvent control group.The sensitization rate was 33.3% (5/15) in the TCE treatment group and 38.5% (5/13) in the TCE+poly I:C treatment group, with no statistical differences.The liver/body coefficients in the TCE sensitized group and the TCE+poly I:C sensitized group were significantly higher than that in the solvent control group (P<0.01).No difference in the serum levels of ALT and AST was observed among the blank control group, the solvent control group, and the non-sensitized group.Compared with the solvent control group, the serum levels of ALT and AST in the TCE sensitized group and the TCE+poly I:C sensitized group were increased (P<0.01).Compared with the TCE sensitized group, the serum levels of ALT and AST in the TCE+poly I:C sensitized group were higher (P<0.01).Pathology examination of liver showed abnormal cell morphology and cell edema in the TCE sensitized group, and a large area of vacuolar degeneration of cells was observed in the TCE+poly I:C sensitized group, leading to liver cell cytoplasm loose and eosin staining lighter.Immunohistochemistry results showed little C3 fragment in TCE sensitized group, but largely deposited in the TCE+poly I:C group, and none in the blank control group, the solvent control group, and the non-sensitized group.The liver immunohistochemical assay results showed high expression of CD46 in liver cell surface in the blank control group, the solvent control group, and the non-sensitized group, reduced expression in the TCE sensitized group, and minimal in the TCE+poly I:C sensitized group.There was no difference in transcriptions of CD46 among the blank control group, the solvent control group, and the non-sensitized group.However, compared with the solvent control group, the transcription was decreased in the TCE sensitized group and the TCE+poly I:C sensitized group.Compared with the TCE sensitized group, the transcriptions of CD46 in the TCE+poly I:C sensitized group were decreased (P<0.01).
Conclusion CD46 may play an important role in poly I:C exacerbated immune liver injury in TCE sensitized mice.
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