Lactobacillus rhamnosus GG (LGG) is increasingly applied in functional food products and acts as a probiotic model in nutritious and clinical studies. Increasing evidences have revealed the immune modulation of LGG on macrophages. The aim of this study is to investigate the effect of LGG on macrophage polarization of murine bone marrow‐derived macrophages (BMDMs). BMDMs were treated with 10⁸ colony‐forming units (CFU)/ml LGG for 1.5, 3, and 6 hr. Results showed that LGG obviously upregulated the mRNA expression of M1‐associated cytokines (p  < .05), including interleukin‐1 beta (IL‐1β), IL‐6, tumor necrosis factor‐alpha (TNF‐α), and inducible nitric oxide synthase (iNOS), whereas had no effect on the expression of M2‐associated markers (p  > .05), including arginase 1 (Arg1), mannose receptor, and chitinase‐like protein 3 (YM1). Furthermore, LGG markedly increased the expression of pro‐inflammatory cytokines (IL‐12p40, cyclooxygenase‐2 [COX‐2], and interferon‐γ [IFN‐γ]) (p  < .05) and anti‐inflammatory cytokines (IL‐10, IL‐4, and transforming growth factor‐β [TGF‐β]) (p  < .05). In addition, we also found that TLR2/MyD88/MAPK signaling pathway was required for LGG‐induced M1 macrophage polarization and M1‐related cytokines expression. Together, these findings demonstrate that probiotic LGG facilitates M1 polarization of BMDMs, suggesting that LGG may have an immunotherapeutic potential in regulating the host defense against pathogen invasion.

中文翻译：

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鼠李糖乳杆菌 GG 通过激活 TLR2/MyD88/MAPK 信号通路促进小鼠骨髓源性巨噬细胞的 M1 极化。

鼠李糖乳杆菌GG (LGG) 越来越多地应用于功能性食品，并在营养学和临床研究中充当益生菌模型。越来越多的证据揭示了 LGG 对巨噬细胞的免疫调节作用。本研究的目的是研究 LGG 对小鼠骨髓源性巨噬细胞 (BMDM) 巨噬细胞极化的影响。^{BMDMs 用 10 8 个}菌落形成单位 (CFU)/ml LGG处理1.5、3 和 6 小时。结果表明，LGG 显着上调 M1 相关细胞因子的 mRNA 表达 ( p  < .05)，包括白介素-1β (IL-1β)、IL-6、肿瘤坏死因子-α (TNF-α) 和诱导型硝酸盐氧化物合酶 (iNOS)，而对 M2 相关标记物的表达没有影响 ( p > .05)，包括精氨酸酶 1 (Arg1)、甘露糖受体和几丁质酶样蛋白 3 (YM1)。此外，LGG 显着增加了促炎细胞因子（IL-12p40、环氧合酶-2 [COX-2] 和干扰素-γ [IFN-γ]）（p < .05）和抗炎细胞因子（  IL- 10、IL-4 和转化生长因子-β [TGF-β]) ( p  < .05)。此外，我们还发现 TLR2/MyD88/MAPK 信号通路是 LGG 诱导的 M1 巨噬细胞极化和 M1 相关细胞因子表达所必需的。总之，这些发现表明益生菌 LGG 促进 BMDM 的 M1 极化，表明 LGG 可能在调节宿主防御病原体入侵方面具有免疫治疗潜力。