Effect Of Tacrolimus On The Expression Of Toll-like Respectors2and4on Macrophage In The Kidney Of Early Diabetic Rats

Background and objective Diabetic nephropathy is a serious microvascularcomplication of diabetes mellitus and the major cause of chronic renal failure.Thepathogenesis of DN is very complicated and has not been fully elucidated at present.The theory of inflammation is paid more attention in recent years and inflammatorymechanism mainly mediated by macrophages is considered the key factor of sustainabledevelopment. Non-activated macrophages have no injury effect, only activatingmacrophages can be cells which have active biological function. Toll-like receptors isone of the key factor involved in the immune inflammation reaction,and thought to bethe principal part which mediated immune and inflammatory reaction.Tacrolimus（FK506） is a new type of immunosuppressant, which is mainly used for organtransplant,rheumatism immunological diseases and refractory nephrosis.Our previousstudies have shown that tacrolimus has diabetic renal protective effect by inhibitcalcineurin （CaN） and osteopontin （OPN）.Futher studies find that tacrolimus can inhibitthe activation of macrophages,but the pathogenesis is unclear.Our study will investigatethe regulation of tacrolimus on Toll-like receptor（TLR）2and TLR4expression in thekidney from diabetic rats and explore its possible renoprotection mechanisms.Methods Forty adult male Sprague-Dawley rats were separated into four groups atrandom. Control group （n=10）, model group （n=10）, model group treated withtacrolimus0.5mg·kg^-1d^-1（n=10）, model group treated with tacrolimus1.0mg·kg^-1d^-1（n=10）. Diabetes was induced with streptozotocin (65mg·kg^-1) in rats, and tacrolimus (0.5or1.0mg·kg^-1d^-1) was orally administered once a day for4weeks.Blood glucose, body weight, relative weight of kidney （RKW） and urinary albuminexcretion rate （UAER） were measured after4weeks. ED-1positive cells, NF-κB-p-p65positive cells,TLR2and ED-1double positive cells, TLR4and ED-1double positivecells were measured with immunohistochemistry and double immunohistochemistryimmunostaining in the kidney.Results Compared with the control group, model group rats showed as a bloodglucose increased, weight loss, relative kidney weight （RKW） increased.Tacrolimus didnot prevent elevated blood glucose and weight loss of the model group. Increased RKWwas only significantly reduced by tacrolimus treatment with1.0mg·kg^-1d^-1（P<0.05）.Elevated24h urinary albumin excretion was markedly attenuated by Tacrolimustreatment with0.5and1.0mg·kg^-1d^-1（P<0.05,0.01）. There were markedaccumulation of ED-1positive cells in diabetic kidney, which were not inhibited bytreatment with Tacrolimus （P<0.01）. NF-κB-p-p65positive cells, ED-1and TLR2double positive cells, ED-1and TLR4double positive cells were significantly increasedin kidneys from model group （P<0.01）, while they were significantly inhibited byTacrolimus treatment （P<0.05）.Conclusion Increased TLR2and TLR4expression on macrophage in the kidney ofearly diabetic rats may be correlated with inflammatory response caused by macrophageactivation. Tacrolimus may directly or indirectly downregulate TLR2and TLR4expression on macrophage and inhibit inflammatory response related to TLR-NF-κBsignal transduction in the kidney.