| Objective (1) To investigate whether iNOS mediates lupus nephritis(LN) in BXSB mice. (2) To investigate whether methylprednisolone(MPS) and puerarin ameliorate LN in BXSB mice via inhibiting iNOS expression in kidneys of BXSB mice and/or relieving peroxidative damages caused by free radicals originated largely from iNOS-synthesized nitric oxide(NO). Methods Eighteen 18-week-old male BXSB mice displaying clinical symptoms of glomerulonephritis are randomly grouped into three, i.e. MPS group, puerarin group and BXSB control group,with 6 mice in each group. Mice in MPS group are treated(i.p.) with MPS (25mg/kg.d) dissolved in N.S. and mice in puerarin group are treated with puerarin (50mg/kg.d) for 3 weeks. Mice in BXSB control group are given N.S. alone. 6 age- and sex- matched BALB/c mice are used as normal mice(non-LN) controls that are treated in the same way as the BXSB controls. 24h total volume urines of all mice are collected at the end of every week's treatment, with hydrochloric acid as preservative. After three weeks' treatment, all mice are killed. Blood are collected and sera are separated immediately. Mice's kidneys are also removed and put into liguid nitrogen as soon as possible. iNOS expression is investigated by means of RT-PCR and immunohistochemistry. Urinary protein, urinary nitrite/nitrate production, serum MDA and SOD levels are also measured. Results (1) Compared with BXSB control mice, 24h total amount of urinary protein of mice in both MPS and puerarin groups significantly decrease after three weeks' treatment(p<0.01).(2) Compared with BXSB control mice, 24 total amount of urinary nitrate/nitrite production of mice in MPS group significantly decrease after treatment(p<0.05), while that of mice in puerarin group doesn't decrease(p>0.05). Urinary nitrate/nitrite excretion of mice in MPS and BXSB control group positively correlate with their urinary protein levels(r=0.537,P<0.01 and r=0.681,P<0.01 respectively).(3) In comparison with BXSB control mice, serum MDA levels of mice in both MPS and puerarin groups decrease significantly(p<0.01);Serum MDA levels of BXSB mice positively correlate with urinary protein levels(r=0.720,P<0.01).(4) Serum SOD levels of both MPS and puerarin groups are higher than that of BXSB control mice and lower than that of BALB/c mice(p<0.01). Serum SOD levels of BXSB mice negatively correlate with urinary protein levels(r=0.720,P<0.01).(5) Semi-quantative RT-PCR demonstrates that iNOS is strongly expressed in kidneys of all BXSB mice, while no signals of expression are found in kidneys of BALB/c mice. iNOS expression in kidneys of mice in MPS group dramatically reduce in comparison with that of BXSB control mice(p<0.01), but no significant iNOS expression difference is found between mice in puerarin group and BXSB control group(p>0.05).(6) Histological examination shows that kidneys of BXSB mice present various pathological alterations similar to human LN, such as mesangial cells proliferation , endothelial cells proliferation, interstitial inflammation, cellular crescent formation, etc.. Immunohistochemistry shows that, in kidneys of BXSB control mice, strong iNOS staining is found in cytoplasm of tubular epithelial cells, glomerular and interstitial infiltrating monocytes. Weaker iNOS staining is found in kidneys of mice in MPS group in the same location as the BXSB control mice. Although the number of infiltrating monocytes in the renal interstitium and glomeruli reduces, the iNOS staining in kidneys of puerarin group mice is still as strong as that of BXSB control mice. (7)No signals of iNOS expression are detected in kidneys of BALB/c mice, whether by means of RT-PCR or immunohistochemistry.Conclusion (1) iNOS and iNOS-synthesized NO may mediate LN in BXSB mice.(2) MPS can reduce urinary protein and ameliorate LN of BXSB mice, partly via inhibiting iNOS expression in kidney and thus decreasing NO production; partly via relieving peroxidative damages caused by free radicals originated largely from iNOS-synthesized NO.(3) Puer...
|
PDF Full Text Request