Xiao Zihao, Wang Yajie, Chen Yuye, Jin Ling, Shi Yuanhui, Liu Can, Fu Cong, Cao Yuhan
Department of Nephrology, Yi Ji Shan Hospital affiliated to Wannan Medical College, Wuhu, People's Republic of China.
Anesthesia Laboratory & Training Center of Wannan Medical College, Wuhu, People's Republic of China.
Am J Physiol Renal Physiol. 2025 Jan 1;328(1):F131-F151. doi: 10.1152/ajprenal.00219.2024. Epub 2024 Dec 10.
Macrophages are recognized as vital players in renal fibrosis, with a high degree of heterogeneity and plasticity, and the triggering receptor expressed on myeloid cell-2 (TREM-2) is highly expressed on macrophages and participates in the progression of tissue fibrosis. However, the mechanism by which TREM-2 mediates the progression of renal fibrosis is still unclear. Our study revealed that exosomes derived from TREM-2-deficient (TREM-2) macrophages suppressed the progression of fibrosis, as indicated by a greater matrix metalloproteinase-9 (MMP-9)/tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) ratio at the protein level in secreted exosomes than in exosomes from wild-type (WT) macrophages in the fibrotic microenvironment. In addition, renal tubular epithelial cells (TECs) engulfed these nanoscale vesicles, and the expression of collagen I and α-smooth muscle actin (α-SMA) (a fibrosis-related marker) was obviously decreased. Through RNA-seq, we found that TREM-2 macrophages increase the MMP-9/TIMP-1 ratio in their exosomes via the heat shock protein a1b (HSPa1b)/AKT pathway. Notably, renal fibrosis was effectively alleviated in the obstructed kidneys of mice that received a renal pelvis injection of an adeno-associated virus (AAV-shTREM-2) containing the sequence used to silence TREM-2. However, VER-155008 (an inhibitor of HSPa1b) and Ly294002 (an inhibitor of AKT) reversed this effect. Moreover, polyclonal antibodies against TREM-2 also effectively relieved unilateral ureteral obstruction (UUO)-induced renal fibrosis. Overall, we validated that knocking down TREM-2 expression can inhibit the progression of renal fibrosis through a macrophage exosome-dependent pathway both in vitro and in vivo. Hence, our findings suggest that TREM-2 is a potential therapeutic target for chronic kidney disease (CKD). Renal fibrosis is a common pathological feature of CKD, resulting in irreversible loss of function and structure. However, effective therapies for CKD are currently limited. We found that the deletion of TREM-2 in macrophages increased the MMP-9/TIMP-1 ratio in exosomes, shifting toward the degradation of the extracellular matrix (ECM) and the alleviation of renal fibrosis. Furthermore, polyclonal antibodies against TREM-2 effectively suppressed renal fibrosis. These findings provide evidence that TREM-2 is a potential therapeutic target for CKD.
巨噬细胞被认为是肾纤维化的关键参与者,具有高度的异质性和可塑性,髓样细胞触发受体2(TREM-2)在巨噬细胞上高表达,并参与组织纤维化的进展。然而,TREM-2介导肾纤维化进展的机制仍不清楚。我们的研究表明,来自TREM-2缺陷(TREM-2-/-)巨噬细胞的外泌体抑制了纤维化的进展,这表现为在纤维化微环境中,分泌的外泌体中基质金属蛋白酶-9(MMP-9)/基质金属蛋白酶组织抑制因子-1(TIMP-1)的蛋白水平比值,高于野生型(WT)巨噬细胞来源的外泌体。此外,肾小管上皮细胞(TECs)吞噬了这些纳米级囊泡,I型胶原蛋白和α-平滑肌肌动蛋白(α-SMA)(一种纤维化相关标志物)的表达明显降低。通过RNA测序,我们发现TREM-2-/-巨噬细胞通过热休克蛋白a1b(HSPa1b)/AKT途径增加其外泌体中的MMP-9/TIMP-1比值。值得注意的是,在接受肾盂注射含有用于沉默TREM-2序列的腺相关病毒(AAV-shTREM-2)的小鼠梗阻肾脏中,肾纤维化得到有效缓解。然而,VER-155008(一种HSPa1b抑制剂)和Ly294002(一种AKT抑制剂)逆转了这种效应。此外,抗TREM-2多克隆抗体也有效缓解了单侧输尿管梗阻(UUO)诱导的肾纤维化。总体而言,我们验证了敲低TREM-2表达可通过巨噬细胞外泌体依赖性途径在体外和体内抑制肾纤维化的进展。因此,我们的研究结果表明,TREM-2是慢性肾脏病(CKD)的一个潜在治疗靶点。肾纤维化是CKD的常见病理特征,会导致功能和结构的不可逆丧失。然而,目前CKD的有效治疗方法有限。我们发现巨噬细胞中TREM-2的缺失增加了外泌体中的MMP-9/TIMP-1比值,转向细胞外基质(ECM)的降解和肾纤维化的缓解。此外,抗TREM-2多克隆抗体有效抑制了肾纤维化。这些发现提供了证据表明TREM-2是CKD的一个潜在治疗靶点。
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