ABSTRACT
Objective To investigate the effects of peptidoglycan (PGN) with different concentrations on Toll-like receptor 2 (TLR2),Toll-like receptor 4 (TLR4) expression in corneal epithelial cells of mice.Methods Corneal epithelial cells of c57 mice were cultured in vitro.Cells were divided into blank control group and 10 mg · L-1 group,30 mg · L-1 gruop and 80 mg · L-1 group (treated by different concentration of PGN for 12 hours).In the meantime,the cells in 30 mg · L-1 group were cultured for different times(named 12 hours group,24 hours group,36 hours group).Expressions of TLR2 and TLR4 mRNA and protein in different group were measured by RT-PCR and flow cytometry.Results Compared with control group (1.00 ± 0.14,1.00 ± 0.01),the expression of TLR2,LR4 mRNA in 10 mg · L-1 group (4.35 ± 0.46,3.53 ± 0.50),30 mg · L-1 group (8.06 ±0.72,5.31 ±0.34),80 mg · L-1 group (2.93 ±0.46,2.23 ±0.04) were increased,the differences were statistically significant (all P ＜ 0.05).Compared with control group,the expression of TLR2,TLR4 protein in different concentration group and 12 hour group were increased,the differences were statistically significant (all P ＜ 0.05).Conclusion PGN can up-regulate both mRNA and protein expression of TLR2 and TLR4 in corneal epithelial cells of mice,suggest that TLR2 and TLR4 in the corneal epithelial cell can recognize some exogenous pathogen and regulate the inflammatory reaction,which are closely related to the occurrence and development of infectious keratitis.
ABSTRACT
<p><b>OBJECTIVE</b>To analyze the biochemical and pathological changes in mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet combined with low-dose streptozotocin (STZ) injections.</p><p><b>METHODS</b>C57BL/6J mice were divided randomly into normal control group (NC group), high-fat diet group (HC group) and high-fat diet plus STZ group (HC+STZ group). The mice were fed on normal chow or a high-fat diet for 1 month before two introperitoneal injections of STZ (40 mg/kg) or citrate buffer with an interval of 24 h as appropriate. Fasting blood glucose (FBG) was detected every week for 4 weeks, and oral glucose tolerance test (OGTT) was performed one month after the injections, after which the biochemical profiles, islet and liver were evaluated by immunohistochemical and pathological analysis.</p><p><b>RESULTS</b>In HC+STZ group, FBG was above the cutoff value (13.89 mmol/L) in 75% of the mice at 1 week after STZ injections and in all the mice at two weeks except for the death of 1 mouse, with a success rate of modeling of 91.3%. FBG in HC group, though slightly higher than that in NC group, remained normal (6.8 mmol/L). The body weight in HC+STZ and HC groups was significantly higher than that in NC group after feeding but without obvious increases after the injections (P<0.01). Blood glucose in HC+STZ group at 0.5 to 2 h after OGTT and the area under curve (AUC) were higher than those in NC and HC groups (P<0.01); the AUC in HC group was a also higher than that in NC group (P<0.05). Plasma creatinine was significantly higher in HC+STZ group than in NC (P<0.01) and HC (P<0.05) groups. Insulin secretion by the islets decreased obviously in HC+STZ and HC group. The mice in HC+STZ group showed atrophy, fibrosis, and vacuolization in the islets with mild fatty liver but no visible renal pathologies.</p><p><b>CONCLUSION</b>High-fat diet and low-dose STZ injections can induce T2DM in mice with very similar biochemical and pathological changes to human T2DM and with such complications as fatty liver.</p>