Effects of hypoxia on iron metabolism of rat L6 skeletal muscle cells / 生理学报

The present study was aimed to investigate the effects of hypoxia on iron metabolism of skeletal muscle. Rat L6 skeletal muscle cells were randomly divided into three groups which were exposed to hypoxia (1% O(2)) for 0, 12, 24 h, respectively. Iron isotope tracing method was used to determine iron uptake and release. Iron content of labile iron pool (LIP) was investigated by flow cytometry, and the expressions of transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1), hypoxia-inducible transcription factor-1 (HIF-1) in L6 cells were observed by Western blot. The results showed that, compared with 0-hour hypoxia group, 12-hour hypoxia group exhibited significantly increased iron uptake and LIP (P < 0.05), as well as decreased iron release (P < 0.01). Not only iron uptake and release, but also LIP in 24-hour hypoxia group were significantly decreased, compared with those in 0- and 12-hour hypoxia groups (P < 0.01). The expressions of HIF-1, DMT1 (IRE), DMT1 (non-IRE) and TfR1 in 12-hour hypoxia group were significantly increased compared with those in 0-hour hypoxia group (P < 0.01). On the contrary, the expressions of DMT1 (IRE), DMT1 (non-IRE) and FPN1 in 24-hour hypoxia group were significantly decreased compared with those in the other two groups. However, TfR1 expression in 24-hour hypoxia was higher than those in 0- and 12-hour hypoxia groups (P < 0.05 or P < 0.01). These results suggest hypoxia plays an important role in iron metabolism of skeletal muscle cells. Moderate hypoxia can increase iron uptake and decrease iron release, resulting in higher LIP, but a prolonged hypoxia induces a disordered iron metabolism of skeletal cells.

Expressions of gelatinases in diffuse proliferative lupus nephritis and its clinical significance / 中华风湿病学杂志

Objective To investigate the roles and significances of MMP-2 and MMP-9 in diffuse proliferative lupus nephritis by repeated renal biopsy.Methods Seventeen patients diagnosed by renal biopsy as WHO typeⅣlupus nephritis were analyzed by immunohistochemistry staining for MMP-2 and MMP-9. Double staining for MMP-2 and MT1-MMP,MMP-9 and CD68 were also performed.Patients had repeated renal biopsy after followed up for 2.5 years.The relationship between expressions of gelatinases and pathological activity index and clinical data were studied.Results MMP-2 immunoreactivity was detected in normal controls and was increased in diffuse proliferative lupus nephritis.MMP-9 staining,which was almost negative in normal giomeruli,was increased much more significantly in diffuse proliferative lupus nephritis. The immunoreactivity of MMP-2 and MMP-9 was positive in MT1-MMP staining and CD68-positive macrophages, respectively.The expression of MMP-2 and MMP-9 was reduced by 70% and 62% in 10 patients whose clinical condition was partially alleviated,while the expressions in 7 patients whose clinical condition was not alleviated,were only reduced by 27% and 32%.The staining for MMP-2 and MMP-9 were correlated with activity index of lupus nephritis and proteinuria.Conclusion Up-regulation of gelatinases expression in diffuse proliferate lupus nephritis is correlated to activity index of the disease.