Bishop Estelle Spear, Namkoong Hong, Aurelian Laure, McCarthy Madison, Nallagatla Pratima, Zhou Wenyu, Neshatian Leila, Gurland Brooke, Habtezion Aida, Becker Laren
Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University, Stanford, California.
Stanford University School of Medicine OFDD, Stanford, California.
Gastro Hep Adv. 2023;2(2):261-276. doi: 10.1016/j.gastha.2022.09.006. Epub 2022 Sep 29.
Muscularis macrophages (MMs) are tissue-resident macrophages in the gut muscularis externa which play a supportive role to the enteric nervous system. We have previously shown that age-dependent MM alterations drive low-grade enteric nervous system inflammation, resulting in neuronal loss and disruption of gut motility. The current studies were designed to identify the MM genetic signature involved in these changes, with particular emphasis on comparison to genes in microglia, the central nervous system macrophage population involved in age-dependent cognitive decline.
Young (3 months) and old (16-24 months) C57BL/6 mice and human tissue were studied. Immune cells from mouse small intestine, colon, and spinal cord and human colon were dissociated, immunophenotyped by flow cytometry, and examined for gene expression by single-cell RNA sequencing and quantitative real-time PCR. Phagocytosis was assessed by in vivo injections of pHrodo beads (Invitrogen). Macrophage counts were performed by immunostaining of muscularis whole mounts.
MMs from young and old mice express homeostatic microglial genes, including , , , and . An MM subpopulation that becomes more abundant with age assumes a geriatric state (GS) phenotype characterized by increased expression of disease-associated microglia genes including , , (CD11c), , , , and and diminished phagocytic activity. Acquisition of the GS phenotype is associated with clearance of -synuclein aggregates. Human MMs demonstrate a similar age-dependent acquisition of the GS phenotype associated with intracellular -synuclein accumulation.
MMs demonstrate age-dependent genetic changes that mirror the microglial disease-associated microglia phenotype and result in functional decline.
肌层巨噬细胞（MMs）是肠道外肌层中的组织驻留巨噬细胞，对肠神经系统起支持作用。我们之前已经表明，年龄依赖性的MM改变会引发低度肠神经系统炎症，导致神经元丢失和肠道运动紊乱。当前的研究旨在确定参与这些变化的MM基因特征，特别强调与小胶质细胞中的基因进行比较，小胶质细胞是参与年龄依赖性认知衰退的中枢神经系统巨噬细胞群体。
研究了年轻（3个月）和年老（16 - 24个月）的C57BL/6小鼠以及人体组织。从小鼠小肠、结肠、脊髓和人体结肠中分离免疫细胞，通过流式细胞术进行免疫表型分析，并通过单细胞RNA测序和定量实时PCR检测基因表达。通过体内注射pHrodo珠（Invitrogen）评估吞噬作用。通过对肌层整装片进行免疫染色来进行巨噬细胞计数。
来自年轻和年老小鼠的MMs表达稳态小胶质细胞基因，包括 、 、 和 。一个随着年龄增长而变得更加丰富的MM亚群呈现出老年状态（GS）表型，其特征是与疾病相关的小胶质细胞基因表达增加，包括 、 、 （CD11c）、 、 、 和 ，以及吞噬活性降低。GS表型的获得与α-突触核蛋白聚集体的清除有关。人类MMs表现出类似的与细胞内α-突触核蛋白积累相关的年龄依赖性GS表型获得。
MMs表现出年龄依赖性的基因变化，这些变化反映了与疾病相关的小胶质细胞表型，并导致功能衰退。
