探究耗竭小鼠肾组织自然杀伤(natural killer，NK)细胞对叶酸诱导小鼠急性肾损伤(acute kidney injury，AKI)的作用。

选取C57BL/6J雄性8~10周龄小鼠，随机分为模型组(腹腔注射叶酸250 mg/kg)、模型＋抗小鼠IgG2a抗体组(建模前连续2 d腹腔注射IgG2a抗体200 μg)、模型＋抗小鼠NK1.1抗体组(建模前连续2 d腹腔注射NK1.1抗体200 μg)和对照组(腹腔注射等量0.3 M碳酸氢钠)，每组均5只。各组小鼠于造模后2 d取材，检测血清肌酐、尿素氮、肾脏/体重质量百分比及肾组织病理学改变；流式细胞术分析肾组织中CD4^＋T细胞、CD8^＋T细胞、调节性T细胞、NK细胞的比例，并检测其分泌白细胞介素-17A、干扰素-γ、肿瘤坏死因子-α的能力。模型＋抗小鼠IgG2a抗体组、模型＋抗小鼠NK1.1抗体组造模后2 d以流式细胞术检测肾组织NK细胞耗竭水平，分析肾功能变化，并观察肾脏病理改变。

与对照组相比，模型组小鼠血清肌酐、血尿素氮水平较高，肾组织损伤更严重(P均<0.05)，肾组织中NK细胞比例较高(P<0.05)，其细胞因子干扰素-γ减少、肿瘤坏死因子-α增多(P均<0.05)，而肾组织中的CD4^＋T细胞、CD8^＋T细胞和调节性T细胞比例及其细胞因子则无明显改变。与模型＋抗小鼠IgG2a抗体组相比，模型＋抗小鼠NK1.1抗体组小鼠的肾组织NK细胞显著耗竭，血清肌酐和血尿素氮水平较低，肾组织损伤较轻(P均<0.05)。

使用抗小鼠NK1.1抗体能够显著耗竭小鼠的肾组织NK细胞，减轻叶酸诱导的小鼠AKI，其保护机制与减少小鼠肾组织中的NK细胞浸润、降低促炎细胞因子分泌有关。

To investigate the effect of depleting renal natural killer (NK) cells on folic acid-induced acute kidney injury (AKI) in mice.

Male C57BL/6J mice aged 8-10 weeks old were selected and randomly divided into the following groups (n=5 per group): a model group (intraperitoneal injection of folic acid at 250 mg/kg), a model+ anti-mouse IgG2a antibody group (intraperitoneal injection of 200 μg IgG2a antibody for 2 consecutive days prior to modeling), a model+ anti-mouse NK1.1 antibody group (intraperitoneal injection of 200 μg anti-NK1.1 antibody for 2 consecutive days prior to modeling), and a control group (intraperitoneal injection of an equivalent volume of 0.3 M NaHCO₃). Mice of the control and model groups were sacrificed 2 days after modeling to evaluate serum creatinine, blood urea nitrogen, kidney-to-body weight ratio, and renal histopathological changes. Flow cytometry was performed to analyze the proportions of CD4⁺ T cells, CD8⁺ T cells, regulatory T cells, and NK cells in kidney tissues, as well as their capacity to secrete cytokines as interleukin-17A, interferon-γ, and tumor necrosis factor-α. For the model+ anti-mouse IgG2a antibody group and the model+ anti-mouse NK1.1 antibody group, the renal NK cells depletion efficiency was assessed by flow cytometry 2 days after modeling, along with the analysis of renal function and observation of renal pathological changes.

Compared with the control group, the model group showed significantly higher serum creatinine and blood urea nitrogen levels, as well as more severe renal tissue injury (all P<0.05), while the proportion of NK cells in the kidneys was also significantly increased (P<0.05), accompanied by decreased interferon-γ and increased tumor necrosis factor-α secretion (all P<0.05). In contrast, the proportions of CD4⁺ T cells, CD8⁺ T cells, and regulatory T cells, along with their associated cytokines, showed no significant changes in the renal tissues. Compared with the model+ anti-mouse IgG2a antibody group, the model + anti-mouse NK1.1 antibody group exhibited significant renal NK cells depletion, accompanied by lower serum creatinine and blood urea nitrogen levels and attenuated renal tissue injury (all P<0.05).

The use of anti-mouse NK1.1 antibody significantly depleted NK cells in renal tissues and attenuated folic acid-induced AKI in mice, suggesting that its protective mechanism is associated with reduced NK cells infiltration and decreased pro-inflammatory cytokines secretion in the kidneys.