Ohishi Kensuke, Dora David, Han Christopher Y, Guyer Richard A, Ohkura Takahiro, Kazimierczyk Simon, Picard Nicole, Leavitt Abigail R, Ott Leah C, Rahman Ahmed A, Mueller Jessica L, Shpigel Nahum Y, Jain Nitya, Nagy Nandor, Hotta Ryo, Goldstein Allan M, Stavely Rhian
Department of Pediatric Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Drug Discovery Laboratory, Wakunaga Pharmaceutical Co., Ltd., Akitakata, Hiroshima, Japan.
Inflamm Bowel Dis. 2025 Jan 6;31(1):151-168. doi: 10.1093/ibd/izae155.
Immune cell populations in the intestinal muscularis propria during colitis are poorly resolved. Maintaining homeostasis in this niche is critical, highlighted by the poorer prognosis of inflammatory bowel disease associated with muscularis propria inflammation.
This study utilizes single-cell RNA sequencing to survey the immune cell populations within the muscularis propria of normal colon and dextran sodium sulfate-induced colitis. Findings are validated by immunohistochemistry, flow cytometry and cell-lineage tracing in vivo, and in vitro assays with muscularis macrophages (MMφ).
In naïve conditions, transcriptional duality is observed in MMφs with 2 major subpopulations: conventional resident Cx3cr1+ MMφs and Lyve1+ MMφs. The Lyve1+ population is phagocytic and expresses several known MMφ markers in mouse and human, confirming their identity as a bona fide MMφ subset. Single-cell transcriptomics indicate that resident MMφs are retained during colitis and exhibit plasticity toward an inflammatory profile. Lyve1+ MMφs, which express anti-inflammatory marker CD163, are absent during colitis, as confirmed by flow cytometry. In contrast, lineage tracing finds that resident Cx3cr1+ MMφs remain during colitis and are not completely replaced by the inflammatory infiltrating monocytes. In vitro studies provide biological evidence of the plasticity of resident Cx3cr1+ MMφs in response to lipopolysaccharide (LPS), mirroring transcriptional observations in vivo of their inflammatory plasticity. Potential markers for colitic MMφs, validated in animal models and in individuals with ulcerative colitis, are identified.
Our findings contribute to the understanding of the immune system in the muscularis propria niche during colitis by resolving the heterogeneity and origins of colitic MMφs.
结肠炎期间肠道固有肌层中的免疫细胞群体尚未得到充分解析。维持这一生态位的稳态至关重要，炎症性肠病伴固有肌层炎症时预后较差就凸显了这一点。
本研究利用单细胞RNA测序来调查正常结肠和葡聚糖硫酸钠诱导的结肠炎固有肌层内的免疫细胞群体。研究结果通过免疫组织化学、流式细胞术和体内细胞谱系追踪以及固有肌层巨噬细胞（MMφ）的体外试验进行验证。
在未感染状态下，MMφ中观察到转录二元性，有2个主要亚群：传统驻留Cx3cr1+ MMφ和Lyve1+ MMφ。Lyve1+群体具有吞噬作用，并在小鼠和人类中表达几种已知的MMφ标志物，证实它们作为真正的MMφ亚群的身份。单细胞转录组学表明，驻留MMφ在结肠炎期间得以保留，并表现出向炎症表型的可塑性。流式细胞术证实，表达抗炎标志物CD163的Lyve1+ MMφ在结肠炎期间不存在。相比之下，谱系追踪发现驻留Cx3cr1+ MMφ在结肠炎期间仍然存在，并没有被炎症浸润的单核细胞完全取代。体外研究提供了驻留Cx3cr1+ MMφ对脂多糖（LPS）反应可塑性的生物学证据，反映了其在体内炎症可塑性的转录观察结果。确定了在动物模型和溃疡性结肠炎患者中得到验证的结肠炎MMφ的潜在标志物。
我们的研究结果通过解析结肠炎MMφ的异质性和起源，有助于理解结肠炎期间固有肌层生态位中的免疫系统。
