The surprising influence of gut bacteria

In a recent study published in Scientific Reports, researchers examined the role of specific gut microbes within the secretion of cytokines by peripheral blood mononuclear cells (PBMCs), monocyte-derived macrophages (MDM), and human colorectal adenocarcinoma cell line HT-29 cells and its contribution to the pathogenesis of asthma.

Study: The potential immunomodulatory role of the gut microbiota within the pathogenesis of asthma: an in vitro study. Image Credit: Rybalchenko Nadezhda/Shutterstock.com

Background

Asthma is a highly prevalent lung disease that leads to airway obstruction and chronic inflammation, generally manifesting as coughing, wheezing, tightness within the chest, and difficulty respiratory. It affects over 200 million people worldwide and contributes substantially to the economic health burden.

The multifactorial technique of asthma is related to chronic inflammation of the airways that causes hyper-reactivity within the bronchioles. A genetic predisposition, environmental aspects, weight loss program, and viral infections during childhood are some major risk aspects for asthma.

Increasing evidence shows that the gut microbiome plays a significant role in health and disease and is involved in fundamental processes of immune responses, defense against pathogens, nutrient absorption, and vitamin production.

Microbiological stimulation within the neonatal period is believed to play a crucial role within the maturation of gastrointestinal lymph tissue, the diversification of antibodies within the gastrointestinal tract, and immunoglobulin A production.

On condition that gut microbiome dysbiosis in early childhood can have an effect on the maturation of the immune system, it can be crucial to grasp the role of specific gut microbes within the pathogenesis of asthma.

Concerning the study

In the current study, the researchers examined the influence of lysates from Ruminococcus albus, Parabacteroides distasonis, Clostridium perfringens, and Bacteroides vulgatus on the secretion of chosen cytokines by PBMCs, HT-29 cells, and MDMs.

Enzyme-linked immunosorbent assays (ELISA) were conducted to research the cytokine secretion after HT-29 cells, MDMs, and PBMCs were stimulated and incubated with lysates from R. albus, P. distasonis, C. perfringens, and B. vulgatus.

Previous studies have reported that fecal samples from neonates at high risk of developing asthma showed fewer strains of  Faecalibacterium, Lachnospira, Rothia, and Veillonella.

Moreover, newborns with an increased abundance of Bacteroides and Streptococcus species and a lower abundance of Ruminococcus gnavus and Bifidobacterium species within the fecal samples were at a better risk of asthma and atopy.

Studies have also found that the gut’s decreased abundance of Akkermansia, Bifidobacteria, and Faecalibacterium species predisposes children to a better risk of asthma.

Given the evidence linking changes in gut microbial abundance to the chance of asthma, the researchers attempted to research whether lysates from R. albus, P. distasonis, C. perfringens, and B. vulgatus had an impact on the secretion of interleukins (IL) 1β, IL-10, IL-6, and tumor necrosis factor-alpha (TNF-α).

Results

The bronchial hyperresponsiveness that happens during asthma often has a changing pathogenetic basis. Chronic inflammation contributes significantly to bronchial hyperresponsiveness throughout the initial stages of asthma, while tissue remodeling within the airways is essentially responsible within the later stages.

The bronchial structural cells release inflammatory mediators akin to cytokines and chemokines required for inflammation amplification, and the epithelium within the bronchioles is actively involved in asthma pathogenesis.

Interactions with the infectious agent in asthma patients end in a decrease in interferon production by the bronchial epithelial cells, lowering the defense responses against these agents.

The findings from the current study showed that lysates from specific gut bacteria could modify the secretion of inflammatory mediators akin to IL-10, IL-6, IL-1β, and TNF-α.

The outcomes indicated that lysates from C. perfringens, and B. vulgatus significantly decreased the secretion of IL-1β by MDMs at doses of 400 micrograms. Moreover, the secretion of IL-6 by MDMs and PBMCs was significantly higher after the administration of lysates from P. distasonis and C. perfringens.

Lysates from P. distasonis, C. perfringens, and B. vulgatus at 100 micrograms were found to extend the secretion of IL-10 by PBMCs. In contrast, those from P. distasonis, C. perfringens, B. vulgatus, and R. albus caused an analogous increase in IL-10 secretion by MDMs.

Moreover, lysates from B. vulgatus and P. distasonis were found to extend the secretion of TNF-α by MDMs and HT-29 cells.

Conclusions

Overall, the findings reported that lysates from R. albus, P. distasonis, C. perfringens, and B. vulgatus could increase the secretion of cytokines akin to IL-10, IL-6, and TNF-α by PBMCs, HT-29 cells, and MDMs.

The modified secretion of pro-inflammatory cytokines through the motion of those bacterial lysates could contribute to the pathogenesis of asthma.