背景:我们最近证明,腹泻型肠易激综合征(IBS-D)受试者具有较高的产生硫化氢(H2S)的梭菌和脱硫弧菌的相对丰度(RA),便秘为主的IBS(IBS-C)受试者的甲烷菌甲烷菌甲磺酸杆菌的RA较高。
目的:在本研究中,我们研究了产甲烷菌或H2S产生菌增加对大鼠模型粪便表型的影响.
方法:成年Sprague-Dawley大鼠饲喂高脂饮食(HFD)60天,以增加M.smithii水平,然后用水(对照)或产甲烷抑制剂灌胃10天。为了增加H2S生产商,大鼠用F.varium或D.piger灌胃。测量粪便稠度(粪便湿重(SWW))和气体产生。对粪便样品进行16SrRNA基因测序。
结果:在HFD饮食喂养的大鼠(N=30)中,52天后,粪便中的M.smithii水平增加(P<0.001),与59天SWW显著降低(P<0.0001)相关(R=-0.38,P=0.037)。在洛伐他汀内酯治疗的大鼠中,小肠M.smithii水平显着降低(P<0.0006),和SWW增加(正常)洛伐他汀羟酸处理的大鼠(P=0.0246),vs.对照(N=10/组)。在第10天,猪灌胃大鼠(N=16)的SWW显着增加(P<0.0001),在所有时间点的F.varium-gavaged大鼠(N=16)中,vs.controls,粪便H2S产量增加。16S测序显示,用H2S产生剂灌胃的大鼠粪便微生物群发生变化,其他H2S生产者的相对丰度(RA)较高,特别是在接受F.gavaged大鼠中的Lachnoshileaceae和Bilophila,和萨特雷拉在D.猪灌胃的老鼠中。
结论:这些发现表明,在大鼠模型中,M.smithii水平升高会导致便秘样表型,这在甲烷生成抑制剂的作用下是部分可逆的。而用H2S生产者D.piger或F.varium灌胃会导致其他H2S生产者和腹泻样表型的定植增加。这支持了在IBS-C和IBS-D受试者中确定的产甲烷菌和H2S生产者的RA增加的作用。分别,有助于粪便表型。
BACKGROUND: We recently demonstrated that diarrhea-predominant irritable bowel syndrome (IBS-D) subjects have higher relative abundance (RA) of hydrogen sulfide (H2S)-producing Fusobacterium and Desulfovibrio species, and constipation-predominant IBS (IBS-C) subjects have higher RA of methanogen Methanobrevibacter smithii.
OBJECTIVE: In this study, we investigate the effects of increased methanogens or H2S producers on stool phenotypes in rat models.
METHODS: Adult Sprague-Dawley rats were fed high-fat diet (HFD) for 60 days to increase M. smithii levels, then gavaged for 10 days with water (controls) or methanogenesis inhibitors. To increase H2S producers, rats were gavaged with F. varium or D. piger. Stool consistency (stool wet weight (SWW)) and gas production were measured. 16S rRNA gene sequencing was performed on stool samples.
RESULTS: In HFD diet-fed rats (N = 30), stool M. smithii levels were increased (P < 0.001) after 52 days, correlating with significantly decreased SWW (P < 0.0001) at 59 days (R = - 0.38, P = 0.037). Small bowel M. smithii levels decreased significantly in lovastatin lactone-treated rats (P < 0.0006), and SWW increased (normalized) in lovastatin hydroxyacid-treated rats (P = 0.0246), vs. controls (N = 10/group). SWW increased significantly in D. piger-gavaged rats (N = 16) on day 10 (P < 0.0001), and in F. varium-gavaged rats (N = 16) at all timepoints, vs. controls, with increased stool H2S production. 16S sequencing revealed stool microbiota alterations in rats gavaged with H2S producers, with higher relative abundance (RA) of other H2S producers, particularly Lachnospiraceae and Bilophila in F. varium-gavaged rats, and Sutterella in D. piger-gavaged rats.
CONCLUSIONS: These findings suggest that increased M. smithii levels result in a constipation-like phenotype in a rat model that is partly reversible with methanogenesis inhibitors, whereas gavage with H2S producers D. piger or F. varium results in increased colonization with other H2S producers and diarrhea-like phenotypes. This supports roles for the increased RA of methanogens and H2S producers identified in IBS-C and IBS-D subjects, respectively, in contributing to stool phenotypes.