Gut microbiome and human health: Exploring how the probiotic genus Lactobacillus modulate immune responses

Abstract

The highest density of microbes resides in human gastrointestinal tract, known as “Gut microbiome”. Of note, the members of the genus Lactobacillus that belong to phyla Firmicutes are the most important probiotic bacteria of the gut microbiome. These gut-residing Lactobacillus species not only communicate with each other but also with the gut epithelial lining to balance the gut barrier integrity, mucosal barrier defence and ameliorate the host immune responses. The human body suffers from several inflammatory diseases affecting the gut, lungs, heart, bone or neural tissues. Mounting evidence supports the significant role of Lactobacillus spp. and their components (such as metabolites, peptidoglycans, and/or surface proteins) in modulatingimmune responses, primarily through exchange of immunological signals between gastrointestinal tract and distant organs. This bidirectional crosstalk which is mediated by Lactobacillus spp. promotes anti-inflammatory response, thereby supporting the improvement of symptoms pertaining to asthma, chronic obstructive pulmonary disease (COPD), neuroinflammatory diseases (such as multiple sclerosis, alzheimer’s disease, parkinson’s disease), cardiovascular diseases, inflammatory bowel disease (IBD) and chronic infections in patients. The metabolic disorders, obesity and diabetes are characterized by a low-grade inflammation. Genus Lactobacillus alleviates metabolic disorders by regulating the oxidative stress response and inflammatory pathways. Osteoporosis is also associated with bone inflammation and resorption. The Lactobacillus spp. and their metabolites act as powerful immune cell controllers and exhibit a regulatory role in bone resorption and formation, supporting bone health. Thus, this review demonstrated the mechanisms and summarized the evidence of the benefit of Lactobacillus spp. in alleviating inflammatory diseases pertaining to different organs from animal and clinical trials. The present narrative review explores in detail the complex interactions between the gut-dwelling Lactobacillus spp. and the immune components in distant organs to promote host’s health.

The effects of dairy on the gut microbiome and symptoms in gastrointestinal disease cohorts: a systematic review

“…This was shown in studies using a range of fermented dairy test foods (fermented milks, kefir, yogurt, and cheese whey protein), providing supporting evidence that fermented dairy foods can positively influence gut microbial characteristics (Kato et al, 2004; Matsumoto et al, 2010; Sprong et al, 2010; Veiga et al, 2010, 2014; Liu et al, 2015; Yilmaz et al, 2019; Li et al, 2020; Zhang et al, 2020). Lactobacillus and Bifidobacterium are considered commensal gut genera, wherein increased relative abundances have been shown to benefit the host (O’Callaghan and van Sinderen, 2016; Hidalgo-Cantabrana et al, 2017; Dempsey and Corr, 2022; Rastogi and Singh, 2022). Thus, increasing the intake of fermented dairy foods may ultimately provide part of a solution in correcting apparent gut microbial dysbiosis in such gastrointestinal disease cohorts.…”

In Vitro Evaluation of the Most Active Probiotic Strains Able to Improve the Intestinal Barrier Functions and to Prevent Inflammatory Diseases of the Gastrointestinal System

“…In recent years, great progress was achieved in the study of the mechanisms of symbiosis between lactic acid bacteria and the host. Their main beneficial effects have been shown to include the regulation of the imbalance of the intestinal flora [ 42 ], the strengthening of the intestinal barrier functions [ 23 , 27 , 36 ], the maintenance of homeostasis [ 36 , 43 ], the regulation of the immune system [ 43 ], and the production of neurotransmitters (gut–brain axis) [ 44 ]. It has been also shown that the exopolysaccharide (EPS) produced by lactobacilli has the peculiar ability to modify the microbiota [ 45 ], and to improve the colonization and growth of intestinal bacteria by acting as a carbon source [ 46 ].…”

Demonstration of safety characteristics and effects on gut microbiota of Lactobacillus gasseri HMV18

“…The genus Lactobacillus is belonged to phyla Firmicutes, and it is an important constituent of the gut microbiome [4]. These gut-residing Lactobacillus species not only contribute to microflora but also improve the gut barrier integrity [5]. Some strains of Lactobacillus gasseri were proven to be benefit to lipid metabolism [6,7], decreased the Irritable Bowel Syndrome symptom score [8] and changed the composition of intestinal microbiota [9].…”