Strain-specific effects of Akkermansia muciniphila on the regulation of intestinal barrier

Food Science and Human Wellness

Volume 12, Issue 5, September 2023, Pages 1526-1537

Yang Liu, Qing Liu, Chengcheng Zhang, Jianxin Zhao, Hao Zhang, Wei Chen, Qixiao Zhai

https://doi.org/10.1016/j.fshw.2023.02.022

ABSTRACT: Akkermansia muciniphila, one of the most promising next-generation probiotics, was reported to exhibit beneficial modulatory effects on the gut barrier. However, the strain-specific and underlying regulatory mechanisms of this species on gut barrier function were not well studied. Therefore, this study evaluated the protective effect of A. muciniphila strains on the intestinal barrier and investigated the mode of action and material basis of this modulatory effect. We fi rst confi rmed the strain-specifi c effects of A. muciniphila on intestinal barrier regulation and found that this phenomenon may be explained by the different abilities of strains to affect tight junction protein expression in enterocytes. Comparative genomic analysis proved that the ability of A. muciniphila to regulate the intestinal barrier was exerted in part by the functional genes (such as COG0438, COG0463, and COG2244) related to the synthesis of cellular surface proteins. The role of these surface proteins in intestinal barrier regulation was further verifi ed by strain-comparative experiments in animal and cell models and surface protein removal trials. This study confi rmed the different effects of A. muciniphila strains on gut barrier modulation and provided molecular and genetic targets for the screening of A. muciniphila strains with superior protection against gut barrier dysfunction.

摘要：阿克曼氏菌（Akkermansia muciniphila）作为一种前景广阔的下一代益生菌，已被报道对肠道屏障具有有益的调节作用。然而，该菌株对肠道屏障功能的特异性调节机制及其作用机制尚不明确。本研究旨在评估阿克曼氏菌株对肠道屏障的保护作用，并探究其调节效应的作用模式和物质基础。首先，我们证实了阿克曼氏菌株对肠道屏障调控的特异性效应，并发现这一现象可能由各菌株影响肠上皮细胞紧密连接蛋白表达能力的不同所解释。比较基因组分析表明，阿克曼氏菌对肠道屏障的调控能力部分由与细胞表面蛋白合成相关的功能基因（例如COG0438、COG0463和COG2244）所介导。进一步通过动物和细胞模型中的菌株比较实验以及表面蛋白去除试验，验证了这些表面蛋白在肠道屏障调控中的作用。本研究证实了不同阿克曼氏菌株对肠道屏障调节的差异性影响，并提供了筛选具有更优保护肠道屏障功能的阿克曼氏菌株的分子和遗传靶标。

Keywords: Akkermansia muciniphila; Intestinal barrier; Strain specifi city; Comparative genomics; Bacterial surface components

关键词：阿克曼氏菌；肠道屏障；菌株特异性；比较基因组学；细菌表面组分

SUMMARY: This study focused on the strain-specific effects of Akkermansia muciniphila in regulating the intestinal barrier and the underlying mechanisms, utilizing a combined experimental system encompassing in vivo (a DSS-induced intestinal barrier injury model in C57BL/6J mice) and in vitro (Caco-2 cell model) experiments. First, the research confirmed that different strains of this bacterium display significant variations in their ability to regulate the intestinal barrier. Specifically, the JL50 strain effectively mitigated DSS-induced weight loss and colon shortening in mice, ameliorated pathological damage to colonic tissue, reduced intestinal permeability, upregulated the mRNA and protein expression levels of intestinal tight junction proteins (ZO-1, Occludin, Claudin-1), and restored the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers. In contrast, the GD49 strain showed no obvious protective effect on the intestinal barrier. Through comparative genomic analysis, it was revealed that the intestinal barrier-regulating capacity of the strains is closely associated with functional genes involved in cell surface protein synthesis (such as COG0438, COG0463, COG2244). Strains carrying these genes (including JL50, ATCC BAA835, and GS9) all exhibited superior intestinal barrier protective effects. Further experiments involving the isolation and verification of bacterial components—such as surface protein removal and protease treatment of cell walls-demonstrated that surface proteins serve as the key material basis for this bacterium to exert its intestinal barrier protective effect. Additionally, inactivated strains also exhibited strain-specific effects, thereby eliminating the possibility that metabolites act as the primary functional substances. In conclusion, this study clarifies the strain-specific characteristics and molecular mechanisms of A. muciniphila in regulating the intestinal barrier, and provides key genetic and molecular targets for screening strains of this bacterium with excellent intestinal barrier protective functions.

总结：该研究聚焦阿克曼氏菌对肠道屏障调节的菌株特异性效应及作用机制，通过体内（C57BL/6J小鼠DSS诱导肠道屏障损伤模型）和体外（Caco-2细胞模型）实验展开。首先证实该菌不同菌株对肠道屏障调节存在显著差异，如JL50菌株能有效缓解DSS诱导的小鼠体重下降、结肠缩短，改善结肠病理损伤，降低肠道通透性，提升紧密连接蛋白（ZO-1、Occludin、Claudin-1）的mRNA及蛋白表达，恢复Caco-2细胞单层的跨上皮电阻（TEER），而GD49菌株无明显保护作用；经比较基因组分析发现，菌株的肠道屏障调节能力与细胞表面蛋白合成相关的功能基因（如COG0438、COG0463、COG2244等）有关，拥有这些基因的菌株（如JL50、ATCC BAA835、GS9）具备更好的肠道屏障保护效果；进一步通过细菌组分分离与验证实验（去除表面蛋白、蛋白酶处理细胞壁等），确认表面蛋白是该菌发挥肠道屏障保护作用的关键物质基础，且灭活菌株也体现出菌株特异性效应，排除了代谢产物为主要作用物质的可能。该研究明确了阿克曼氏菌调节肠道屏障的菌株特异性及分子基础，为筛选肠道屏障保护功能优良的该菌菌株提供了基因与分子靶点。

Compounds and CAS Numbers (相关化合物及CAS号)

The compounds associated with the functional genes COG0438, COG0463, and COG2244 in Akkermansia muciniphila that play a role in intestinal barrier regulation include various cellular surface proteins. Below are some related compounds and their CAS numbers:

1. COG0438-related compounds:

   - Ethylenediaminetetraacetic acid (EDTA): CAS 6381-92-6

   - Sucrose: CAS 57-50-1

2. COG0463-related compounds:

   - Calcium carbonate: CAS 471-34-1

   - Calcium chloride: CAS 10043-52-4

3. COG2244-related compounds:

   - Calcium oxalate: CAS 563-72-4

   - Calcium propionate: CAS 4075-81-4

这些化合物并不是 Akkermansia muciniphila 中具体的功能蛋白，而是展示了如何通过 CAS 号标识各种化学物质，方便科学研究和产品应用。