调节性T细胞在热射病相关性急性肾损伤中的作用机制研究

Mechanism of regulatory T cells in heat stroke-induced acute kidney injury

目的探讨调节性T细胞(Treg)在热射病(HS)相关性急性肾损伤(AKI)中的作用机制。方法将雄性SPF级Balb/c小鼠随机分为对照组、HS组(HS+同型对照抗体)、HS+PC61组、HS+Treg组,每组6只。在室温39.5℃、相对湿度60%环境下1 h使小鼠体温达到42.7℃建立HS小鼠模型,其中HS+PC61组在制模前连续2 d经尾静脉注射PC61抗体(抗CD25)100μg清除Treg;HS+Treg组在制模成功后立刻经尾静脉注射1×10^(6)Treg。制模成功后24 h各组小鼠取材,比较各组间肾脏局部Treg比例,血肌酐(SCr)和肾脏病理损伤情况,血清和肾脏局部γ-干扰素(IFN-γ)和肿瘤坏死因子-α(TNF-α)的表达水平以及肾脏局部浸润中性粒细胞和巨噬细胞的比例。结果HS可以加重肾脏功能和病理损伤,上调肾脏局部及血清炎症因子水平,增加肾脏局部中性粒细胞和巨噬细胞的浸润,与对照组比较,肾脏局部Treg占CD4^(+)T细胞比例(Treg/CD4^(+))减少,差异有统计学意义〔(3.40±0.46)%比(7.67±0.82)%,P<0.01〕。与HS组比较,PC61抗体几乎可以清除肾脏局部Treg〔(0.77±0.12)%比(3.40±0.46)%,P<0.01〕,加重肾脏功能〔SCr(mmol/L):348.22±35.36比254.42±27.40,P<0.01〕和病理损伤〔Paller评分(分):4.70±0.20比3.60±0.20,P<0.01〕,上调肾脏局部组织及血清IFN-γ和TNF-α的表达水平〔血清IFN-γ(ng/L):747.70±64.52比508.46±44.79,血清TNF-α(ng/L):647.41±26.62比464.53±41.80,均P<0.01〕,并增加肾脏局部中性粒细胞和巨噬细胞的浸润〔中性粒细胞比例:(6.63±0.67)%比(4.37±0.43)%,巨噬细胞比例:(38.70±1.66)%比(33.19±1.55)%,均P<0.01〕;而注射异体Treg则可增加肾脏局部Treg比例〔(10.58±1.19)%比(3.40±0.46)%,P<0.01〕,减轻肾脏功能〔SCr(mmol/L):168.24±40.56比254.42±27.40,P<0.01〕和病理损伤〔Paller评分(分):2.73±0.11比3.60±0.20,P<0.01〕,下调肾脏局部组织及血清IFN-γ和TNF-α的表达水平〔血清IFN-γ(ng/L):262.62±22.68比508.46±44.79,血清TNF-α(ng/L):206.41±22.58比464.53±41.80,均P<0.01〕,并减少肾脏局部中性粒细胞和巨噬细胞的浸润〔中性粒细胞比例:(3.04±0.33)%比(4.37±0.43)%,巨噬细胞比例:(25.68±1.93)%比(33.19±1.55)%,均P<0.01〕。结论Treg可能通过减少炎症细胞浸润、下调炎症因子水平参与HS-AKI。

Objective To investigate the mechanism of regulatory T cells(Treg)in heat stroke(HS)-induced acute kidney injury(AKI).Methods Male SPF Balb/c mice were randomly divided into control group,HS group(HS+Rat IgG),HS+PC61 group,and HS+Treg group(n=6).The HS mice model was established by making the body temperature of the mice reach 42.7℃at room temperature 39.5℃with relative humidity 60%for 1 hour.In HS+PC61 group,100μg PC61 antibody(anti-CD25)was injected through the tail vein in consecutive 2 days before the model was established to eliminate Tregs.Mice in HS+Treg group was injected with 1×10^(6)Treg via tail vein immediately after successful modeling.The proportion of Treg infiltrated in the kidney,serum creatinine(SCr)and histopathology,levels of interferon-γ(IFN-γ)and tumor necrosis factor-α(TNF-α)both in the serum and kidney tissue,as well as proportion of neutrophils and macrophages located in the kidney were observed at 24 hours after HS.Results HS dampened renal function and exaggerated kidney injury,up-regulated levels of inflammatory cytokines both in local kidney and circulation,and increased infiltration of neutrophils and macrophages to the injured kidneys.The proportion of Treg(Treg/CD4^(+))infiltrated in kidney was significantly decreased in HS group,compared with control group[(3.40±0.46)%vs.(7.67±0.82)%,P<0.01].Compared with HS group,local Tregs in kidney were almost completely depleted via PC61 antibody[(0.77±0.12)%vs.(3.40±0.46)%,P<0.01].Depletion of Tregs could exacerbate HS-AKI,indicating by increased serum creatinine[SCr(mmol/L):348.22±35.36 vs.254.42±27.40,P<0.01]and pathological injury(Paller score:4.70±0.20 vs.3.60±0.20,P<0.01),incremental levels of IFN-γand TNF-αboth in injured kidney and serum[serum IFN-γ(ng/L):747.70±64.52 vs.508.46±44.79,serum TNF-α(ng/L):647.41±26.62 vs.464.53±41.80,both P<0.01],and more infiltrated neutrophils and macrophages in the injured kidney[neutrophil proportion:(6.63±0.67)%vs.(4.37±0.43)%,macrophage proportion:(38.70±1.66)%vs.(33.19±1.55)%,both P<0.01].On the contrast,adoptive transfer of Tregs could reverse the aforementioned effects of Treg depletion,indicating by incremental proportion of Tregs in the injured kidney[(10.58±1.19)%vs.(3.40±0.46)%,P<0.01],decreased serum creatinine[SCr(mmol/L):168.24±40.56 vs.254.42±27.40,P<0.01]and pathological injury(Paller score:2.73±0.11 vs.3.60±0.20,P<0.01),reduced levels of IFN-γand TNF-αboth in injured kidney and serum[serum IFN-γ(ng/L):262.62±22.68 vs.508.46±44.79,serum TNF-α(ng/L):206.41±22.58 vs.464.53±41.80,both P<0.01],and less infiltrated neutrophils and macrophages in the injured kidney[neutrophil proportion:(3.04±0.33)%vs.(4.37±0.43)%,macrophage proportion:(25.68±1.93)%vs.(33.19±1.55)%,both P<0.01].Conclusion Treg might be involved in HS-AKI,possibly via down-regulation of pro-inflammatory cytokines and infiltration of inflammatory cells.