在临床前研究中,果胶及其衍生物已被证明可以调节免疫信号以及肠道微生物群。这可能构成补充特定果胶多糖赋予对病毒性呼吸道感染的保护作用的机制。在双盲中,安慰剂对照鼻病毒(RV16)攻击研究,健康志愿者随机服用安慰剂(0.0克/天)(N=46),低剂量(0.3g/天)(N=49)或高剂量(1.5g/天)(N=51)胡萝卜来源的鼠李糖半乳糖醛酸-I(cRG-I)持续八周,随后用RV-16攻击。这里,研究了8周cRG-I补充对肠道微生物群的影响。虽然这种非常低剂量的纤维通常不会改变人群中的整体肠道微生物群组成,双歧杆菌属的相对丰度。cRG-1的两种剂量均显着增加(主要是青少年芽孢杆菌和长芽孢杆菌)。此外,每日补充cRG-I导致个体间和个体内微生物群异质性的剂量依赖性减少,表明对肠道微生物群的稳定作用。呼吸道症状的严重程度与cRG-I诱导的微生物变化没有直接相关,但是,Ruminococycaceae家族的几个主要群体和微生物群的丰富度与减少的感染后反应呈正相关。因此,关于调节肠道微生物群组成的当前结果支持了cRG-I在普通感冒感染期间的免疫调节和保护作用。
Pectin and its derivatives have been shown to modulate immune signaling as well as gut microbiota in preclinical studies, which may constitute the mechanisms by which supplementation of specific pectic polysaccharides confers protection against viral respiratory infections. In a double-blind, placebo-controlled rhinovirus (RV16) challenge
study, healthy volunteers were randomized to consume placebo (0.0 g/day) (N = 46), low-dose (0.3 g/day) (N = 49) or high-dose (1.5 g/day) (N = 51) of carrot derived rhamnogalacturonan-I (cRG-I) for eight weeks and they were subsequently challenged with RV-16. Here, the effect of 8-week cRG-I supplementation on the gut microbiota was studied. While the overall gut microbiota composition in the population was generally unaltered by this very low dose of fibre, the relative abundance of Bifidobacterium spp. (mainly B. adolescentis and B. longum) was significantly increased by both doses of cRG-1. Moreover, daily supplementation of cRG-I led to a dose-dependent reduction in inter- and intra-individual microbiota heterogeneity, suggesting a stabilizing effect on the gut microbiota. The severity of respiratory symptoms did not directly correlate with the cRG-I-induced microbial changes, but several dominant groups of the Ruminococcaceae family and microbiota richness were positively associated with a reduced and hence desired post-infection response. Thus, the present results on the modulation of the gut microbiota composition support the previously demonstrated immunomodulatory and protective effect of cRG-I during a common cold infection.