探讨短链脂肪酸(SCFAs)对小鼠肾损伤后炎症及纤维化的影响及其作用机制。

采用双侧肾动脉夹闭25 min诱导缺血再灌注(I/R)肾损伤建立小鼠肾脏纤维化模型后，小鼠随机分为缺血再灌注组(I/R组)、短链脂肪酸组(I/R＋SCFAs组)和短链脂肪酸合并抗CD25单克隆抗体组(I/R＋SCFAs＋anti-CD25组)，并设假手术组(Sham组)，每组6只。I/R＋SCFAs组和I/R＋SCFAs＋anti-CD25组小鼠在术前1周连续饮用SCFAs溶液，且I/R＋SCFAs＋anti-CD25组小鼠在术前2 d和手术当天给予腹腔注射anti-CD25；Sham组小鼠只分离肾动脉不进行夹闭。建模28 d后收集各组小鼠肾组织，进行病理学检测，免疫组织化学检测CD68、肿瘤坏死因子-α(TNF-α)、细胞间黏附分子-1(ICAM-1)、叉头盒转录因子P3(Foxp3)和转录因子维甲酸相关孤儿受体γt(RORγt)的表达，Western印迹检测各组肾组织中Toll样受体4(TLR4)、髓样分化因子88(MyD88)和核转录因子κB p65(NF-κB p65)及α-平滑肌肌动蛋白(α-SMA)等蛋白表达水平。

与Sham组相比，I/R组小鼠病理损伤较重，肾小管间质纤维化增多，免疫组织化学检测显示肾组织CD68、TNF-α、ICAM-1表达显著升高(P均<0.05)，Western印迹检测TLR4、MyD88、NF-κB p65、α-SMA蛋白表达水平显著增多(P均<0.05)。与I/R组相比，I/R＋SCFAs组小鼠肾纤维化程度减轻，肾组织的CD68、TNF-α、ICAM-1表达降低，而且TLR4、MyD88、NF-κB p65、α-SMA蛋白表达水平亦降低(P均<0.05)。与I/R＋SCFAs组相比，I/R＋SCFAs＋anti-CD25组病理损伤加重，Foxp3表达减少，而TNF-α、ICAM-1、RORγt表达升高(P均<0.05)，TLR4、MyD88、NF-κB p65、α-SMA蛋白表达水平有所升高。

SCFAs可能通过TLR4/MyD88/NF-κB通路抑制炎症因子产生，从而减轻肾脏炎症反应和肾纤维化。

To explore the effect and mechanism of short-chain fatty acid (SCFAs) on inflammation and fibrosis of mice with renal ischemia-reperfusion (I/R) injury.

The mouse model of renal fibrosis was established by I/R injury induced by bilateral renal artery clamping for 25 minutes. The successfully modeled mice were randomly divided into I/R group, short-chain fatty acid (I/R+ SCFAs) group, SCFAs plus anti-CD25 monal clonal antibody (I/R+ SCFAs+ anti-CD25) group with 6 mice in each group. Besides, there was also a sham operation group in which renal arteries of the mice were isolated without clamping. Mice of the I/R+ SCFAs group and the I/R+ SCFAs+ anti-CD25 group began to drink SCFAs solution continuously one week before the operation, and I/R+ SCFAs+ anti-CD25 group also received intraperitoneal injection of anti-CD25 two days before operation and on the day after the operation. After 28 days of the modeling, kidney tissues of the mice in each group were collected for pathological detection. The expression of CD68, tumor necrosis factor α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), forkhead box transcription factor P3 (Foxp3), and transcription factor retinoic-related orphan receptor γt (RORγt) were detected by immunohistochemistry. Western blotting was applied to detect the expression levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), nuclear transcription factor κB p65 (NF-κB p65) and α-SMA in renal tissues of all groups.

Compared with sham operation group, the I/R group showed more serious renal pathological injury with renal tubule interstitial fibrosis being increased, and the expressions of CD68, TNF-α, and ICAM-1 in renal tissues were significantly increased in immunohistochemical detection (all P<0.05), while the expression levels of TLR4, MyD88, NF-κB p65, and α-SMA were significantly increased in Western blotting (all P<0.05). Compared with the I/R group, the I/R+ SCFAs group displayed lower level of renal fibrosis, and lower expressions of CD68, TNF-α, and ICAM-1 in renal tissues, while the protein expression levels of TLR4, MyD88, NF-κB p65, and α-SMA were also decreased (all P<0.05). Compared with the I/R+ SCFAs, the I/R+ SCFAs+ anti-CD25 group showed more serious pathological damage, with the Foxp3 expression being decreased, while the expressions of TNF-α, ICAM-1, and RORγt were increased (all P<0.05), and the expression levels of TLR4, MyD88, NF-κB p65, and α-SMA did not show a significant increase.

SCFAs may inhibit the production of inflammatory factors through the TLR4/MyD88/NF-κB pathway, thereby alleviating renal inflammation and renal fibrosis.