[Protective effect of breviscapine on human hepatocytes under hypoxia/re-oxygenation and its possible mechanism]

To explore the protective effect of breviscapine on human hepatocytes (L-02) under hypoxia/re-oxygenation (H/R) and elucidate its possible mechanism.

A in vitro model of H/R was employed to mimic H/R injury of graft organ. L-02 cells were randomly divided into 3 groups: control, H/R and breviscapine treatment (pre-treated with breviscapine and H/R). After a 10 h hypoxic culturing under 1% O(2), 94% N(2) and 5% CO(2), L-02 cells received oxygen for 1, 2, 4, 8, 16 and 24 h respectively. MICA mRNA and protein levels were detected by quantitative real-time polymerase chain reaction (PCR) and Western blot. And the activity of natural killer (NK) cell cytotoxicity for L-02 was measured by lactate dehydrogenase (LDH) release assay. After blocking I/R treatment with NKG2D antibody, the activity of NK cell cytotoxicity for L-02 was detected.

After 10 h hypoxia, MICA mRNA and protein levels significantly increased from 1 h, stayed up-regulated until 8 h and then went back to normal level after reoxygenation versus the control group. The activity of NK cell cytotoxicity for L-02 under the treatment of H/R increased markedly from 1 h post-reoxygenation and stayed up-regulated from 1 h to 8 h versus the control group. After hypoxia, L-02 cells were blocked with NKG2D antibody and the NK cell cytotoxicity for L-02 significantly decreased versus the I/R group. The administration of breviscapine significantly lowered the mRNA and protein levels of MICA in L-02 under I/R and then significantly decreased the NK cell cytotoxicity.

The process of I/R may mediate the NK cell cytotoxicity activity toward to L-02 by inducing a strong increase of MICA at mRNA and protein levels in L-02 cells. And the administration of Breviscapine significantly reduces the NK cell cytotoxicity for L-02 under I/R through the down-regulated expression of MICA.