Smith Phillip D, Ochsenbauer-Jambor Christina, Smythies Lesley E
Department of Medicine (Gastroenterology and Hepatology), University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Immunol Rev. 2005 Aug;206:149-59. doi: 10.1111/j.0105-2896.2005.00288.x.
The gastrointestinal mucosa is the largest reservoir of macrophages in the body. These important effector cells are derived from blood monocytes that are recruited to the lamina propria by endogenous chemoattractants in the non-inflamed mucosa and by inflammatory chemokines and bacterial products during inflammation. In the non-inflamed mucosa, newly recruited pro-inflammatory monocytes are exposed to lamina propria stromal (extracellular matrix) factors that induce phenotypic and functional differentiation into non-inflammatory macrophages. As a consequence of this differentiation, resident lamina propria macrophages are strikingly downregulated for the expression of innate response receptors, such as the receptors for lipopolysaccharide, immunoglobulin G (IgG), and IgA, and the production of pro-inflammatory cytokines, including interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor-alpha. Despite downregulated pro-inflammatory function, strong phagocytic and bactericidal activities remain intact. Thus, in the non-inflamed intestinal mucosa, lamina propria macrophages are non-inflammatory but retain avid scavenger and host defense functions, a unique but ideal phenotype and functional profile for effector cells in close proximity to immunostimulatory microorganisms and products.
胃肠道黏膜是体内最大的巨噬细胞储存库。这些重要的效应细胞源自血液中的单核细胞，在非炎症黏膜中，它们被内源性趋化因子募集到固有层；在炎症期间，则被炎症趋化因子和细菌产物募集到固有层。在非炎症黏膜中，新募集的促炎单核细胞会接触到固有层基质（细胞外基质）因子，这些因子会诱导其表型和功能分化为非炎症性巨噬细胞。这种分化的结果是，固有层常驻巨噬细胞表达先天反应受体（如脂多糖受体、免疫球蛋白G（IgG）和IgA受体）以及促炎细胞因子（包括白细胞介素-1（IL-1）、IL-6、IL-8和肿瘤坏死因子-α）的水平显著下调。尽管促炎功能下调，但强大的吞噬和杀菌活性仍然完好。因此，在非炎症性肠黏膜中，固有层巨噬细胞是非炎症性的，但保留了活跃的清除和宿主防御功能，这对于紧邻免疫刺激微生物及其产物的效应细胞来说，是一种独特而理想的表型和功能特征。
