Toll-like Receptor 4 Signaling Pathway in the Protective Effect of Pioglitazone on Experimental Immunoglobulin A Nephropathy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>In vitro experiments have revealed that toll-like receptor 4 (TLR4) pathway is involved in the progression of immunoglobulin A nephropathy (IgAN) by induction of proinflammatory cytokines. Evidence showed that, in other disease models, peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have been shown to exert anti-inflammatory effects through suppression of the expression and activity of TLR4. However, the interaction between PPAR-γ and TLR4 in IgAN has not been fully studied both in vitro and in vivo. In this study, we explored whether TLR4 pathway attributed to the progression of IgAN in experimental rats.</p><p><b>METHODS</b>Bovine gamma globulin was used to establish IgAN model. Fifty-four Lewis rats were randomly divided into six groups: ControlTAK242, IgANTAK242, toll-like receptor 4 inhibitor (TAK242) groups (rats were administrated with TLR4 inhibitor, TAK242) and ControlPio, IgANPio, Pio groups (rats were administrated with PPAR-γ agonist, pioglitazone). Urinary albumin-to-creatinine ratio (ACR), serum creatinine, and blood urea nitrogen were detected by automatic biochemical analyzer. Renal histopathological changes were observed after hematoxylin-eosin staining, and the IgA deposition in glomeruli was measured by immunofluorescence staining. Real-time polymerase chain reaction and Western blotting were used to detect TLR4 and interleukin-1 beta (IL-1β) message ribonucleic acid (mRNA) and protein expression in renal tissues. Results were presented as mean ± standard deviation. Differences between groups were analyzed by one-way analysis of variance.</p><p><b>RESULTS</b>Compared to normal rats, experimental rats showed higher ACR (4.45 ± 1.33 mg/mmol vs. 2.89 ± 0.96 mg/mmol, P < 0.05), obvious IgA deposition with mesangial hypercellularity, hyperplasia of mesangial matrix accompanied by increased serum IL-1β (48.28 ± 13.49 pg/ml vs. 35.56 ± 7.41pg/ml, P < 0.05), and renal expression of IL-1β and TLR4. The biochemical parameters and renal pathological injury were relieved in both TAK242 group and Pio group. The expressions of renal tissue TLR4, IL-1β, and serum IL-1β were decreased in rats treated with TAK242, and the expression of TLR4 mRNA and protein was significantly reduced in Pio group compared to IgANPiogroup (1.22 ± 0.28 vs. 1.72 ± 0.45, P < 0.01, and 0.12 ± 0.03 vs. 0.21 ± 0.05, P < 0.01).</p><p><b>CONCLUSIONS</b>Our study proves that inflammation mediated by TLR4 signaling pathway is involved in the progression of IgAN in rat models. Moreover, pioglitazone can inhibit the expression of TLR4 in IgAN.</p>

Renal protection of rosiglitazone in hypertensive rats and its relationship with the expression of angiotensin Ⅱ receptors / 中华肾脏病杂志

Objective To observe the role of rosiglitazone in unclipped kidneys of two-kidney- one-clip hypertensive rats and examine its relationship to angiotensinⅡreceptors.Methods Two- kidney-one-clip hypertensive rats were divided randomly into 4 groups as follows:positive control group (CONT),traditional antihypertensive drugs group (TAHD,reserpine 50?g?kg~(-1)?d~(-1), dihydralazine 6.25 mg?kg~(-1)?d~(-1) and hydrochlorothiazide 6.25 mg?kg~(-1)?d~(-1),regular-dose rosiglitazone group (RRGL,rosiglitazone 5 mg?kg~(-1)?d~(-1)),and high-dose rosiglitazone group (HRGL, rosiglitazone 20 mg?kg~(-1)?d~(-1)).Sham operation rats were as negative controls.Each group had 8 rats. Animals were monitored and sacrificed at 10th week.Results Blood systolic pressure in TAHD group and HRGL group was significantly lower than that in CONT group [TAHD(137?27 ) mm Hg and HRGL (143?16) mm Hg vs CONT (191?25 ) mm Hg,P＜0.05],but no significant difference between the former two groups was found.Nor did the blood systolic pressure between RRGL group [(176?18) mm Hg] and CONT group.At 10th week,rats in SHAM group and treated groups had lower urinary urinary protein excretion rate,glomerular injury score and wall-to-lumen ratio of arteriole than those in CONT group [vs CONT urinary protein excretion rate (44.60?17.40) mg/24 h,P＜0.05; vs CONT glomerular injury score 60.85?33.05,P＜0.05;vs CONT wall-to-lumen ratio of arteriole 2.33?1.01,P＜0.01,except TAHD group].Though with the similar level of blood pressure,blood glucose and lipid,HRGL,compared with TAHD group showed lower urinary protein excretion rate [HRGL (16.78?3.50) mg/24 h vs TAHD (27.94?12.79) mg/24 h,P＜0.05],decreased glomerular injury score (HRGL 18.04?7.76 vs TAHD 27.92?6.39,P＜0.05) and wall-to-lumen ratio of arteriole (HRGL 1.75?0.38 vs TAHD 2.16?0.90,P＜0.05) in the cortexes of unclipped right kidneys.The expression of type 1 angiotensinⅡreceptor (AT1R) mRNA was no difference in HRGL group and TAHD group,but the expression of type 2 angiotensinⅡreceptor (AT2R) mRNA was more intensive in HRGL group.Conclusion Rosiglitazone can protect the kidneys from hypertensive injury,especially in high dose.The beneficial effects seem incompletely dependent on the metabolism modulating and reduction of blood pressure,but in relationship to the upregulation of AT2R mRNA.