Intestinal immunity: to be, or not to be, induced? That is the question

The mechanism by which intestinal flora metabolites regulate ILC2s transformation and intestinal immunity through the metabolite-sensitive receptor Ffar2

OBJECTIVE

The objective of this article was to investigate how the metabolites produced by the intestinal flora regulate the transformation of ILC2s and intestinal immunity via the receptor Ffar2, which is sensitive to metabolites.

MATERIALS AND METHODS

Forty male C57BL/6 mice with wild-type characteristics (6-7 weeks in age) and 20 FFAR2-/- mice were acquired from The Jackson Laboratory. The mice were kept in a controlled environment without any disease-causing agents, with the help of air conditioning and a 12-hour cycle of light and darkness. Throughout the experiment, every mouse was provided with unrestricted availability of both food and water. All protocols were performed following the Regulations of Animal Welfare and the recommendations for Animal Testing. According to the research protocol, the mice were categorized into three groups, each consisting of 20 mice. FFAR2-/- mice in the FFAR2-/- group were reared in conventional environments. Male C57BL/6 mice with wild-type characteristics were reared in conventional conditions in the wild-type group. In the group where wild-type mice were inhibited with Ffar2, a total of 20 mice with the wild-type phenotype were chosen to receive intraperitoneal injection of an FFAR2 antagonist at a dosage of 5 mg/kg per day for a continuous period of 3 weeks. qRT-PCR was used to detect the expression of FFAR2 mRNA in the mucosal tissue of the mouse colon. High-throughput sequencing was used to conduct an examination of metabolites in the intestinal tract of mice. Flow cytometry was used to test the quantity of ILC2s. ELISA was used to measure the levels of IL-5 and IL-13 in cellular mouse intestinal mucosal tissues. Flow cytometry was used to detect the quantity of CD4+ and CD8+ T cells. CCL20 and CCL25 expression was analyzed by Western blotting. The level of FFAR2 mRNA expression was higher in the wild-type group than the FFAR2-/- group ( P < 0.05), while it was lower in the wild-type + Ffar2 inhibition group than the wild-type group ( P < 0.05). No variations were observed in the composition of metabolites and levels of major SCFAs in the gut microbiota of mice across all groups ( P > 0.05). The quantity of CRTH2+ and ST2+ cells in the wild-type category exceeded that in the FFAR2-/- category ( P < 0.05), whereas the quantity of CRTH2+ and ST2+ cells in the wild-type + Ffar2 inhibition category was lower than that in the wild-type category ( P < 0.05). The concentrations of IL-5 and IL-13 were higher in the wild-type group compared with the FFAR2-/- group ( P < 0.05), while the wild-type + Ffar2 inhibition group exhibited lower levels of IL-5 and IL-13 than the wild-type group ( P < 0.05). The count of CD4+ T cells and CD8+ T cells in the wild-type group showed an increase in comparison to the FFAR2-/- group ( P < 0.05), whereas the count of CD4+ T cells and CD8+ T cells in the wild-type + Ffar2 inhibition group exhibited a decrease in comparison to the wild-type group ( P < 0.05). The levels of protein expression for CCL20 and CCL25 were higher in the wild-type group compared with the FFAR2-/- group ( P < 0.05), whereas the wild-type + Ffar2 inhibition group exhibited lower protein expression of CCL20 and CCL25 than the wild-type group ( P < 0.05).

CONCLUSION

Ffar2 has a significant regulatory function in the conversion of ILC2s, consequently impacting the immune response in the intestines. Ffar2, a crucial receptor for metabolites produced by the intestinal flora, plays a vital function in controlling the conversion of ILC2s and the overall immune response in the intestines.

Natural Products on Inflammatory Bowel Disease: Role of Gut Microbes

Inflammatory bowel disease (IBD) refers to long-term medical conditions that involve inflammation of the digestive tract, and the global incidence and prevalence of IBD are on the rise. Gut microbes play an important role in maintaining the intestinal health of the host, and the occurrence, development, and therapeutic effects of IBD are closely related to the structural and functional changes of gut microbes. Published studies have shown that the natural products from traditional Chinese medicine have direct or indirect regulatory impacts on the composition and metabolism of the gut microbes. In this review, we summarize the research progress of several groups of natural products, i.e., flavonoids, alkaloids, saponins, polysaccharides, polyphenols, and terpenoids, for the therapeutic activities in relieving IBD symptoms. The role of gut microbes and their intestinal metabolites in managing the IBD is presented, with focusing on the mechanism of action of those natural products. Traditional Chinese medicine alleviated IBD symptoms by regulating gut microbes, providing important theoretical and practical basis for the treatment of variable inflammatory intestinal diseases.

Ascaridia galli infection in chicken: Pathobiology and immunological orchestra

BACKGROUND

Ascaridia galli is the largest gut-dwelling helminth of chickens, which confers adverse effects on meat and egg production; thus, on the animal protein supply and the economy. Both adult and immature parasites affect gut health, but larval stages play a major role in pathology.

AIMS

Here, we present immunology and pathology of A. galli in chickens.

MATERIALS AND METHODS

Literatures were surveyed through online platforms such as PubMed, Google Scholar and Researchgate.

RESULTS

The larvae cause excessive mucus production, damage to the intestinal gland, hemorrhage, anemia, diarrhea, and malnutrition. The adult worms can cause death by intestinal obstruction and intussusception. Although both cellular and humoral immunity are involved in fighting against ascariasis, the role of naturally acquired immunity is poorly defined. In cellular immunity, Th-2 cytokines (IL-4, IL-5, IL-9, and IL-13), goblet cells (mucin), gut-associated lymphoid tissues, CD8α+ intraepithelial cells, TCRγδ + T cells, and TGF-β4 form a protective band. Type 2 immunity provides protection by forming a network of endogenous damage-associated molecular patterns, chitin, and parasitic antigens. Among antibodies, IgY is the most prominent in chickens and provides temporary humoral protection. During parasitic infection, infiltration of various immune cells is evident, especially in the intestinal epithelium, lamina propria, and crypts of the duodenum and jejunum. In chickens older than 12 weeks, gradual reduction of worm burden is more successful than the younger birds. Female chickens exert a short-lived but higher level of protection by passing IgY to chicks in the form of egg yolk antibodies. In laying conditions, immunity differs between breeds. This review provides an overview of the silent but inevitable pathological changes induced by A. galli and the interaction of host immunity with the parasite.

Efficacies of Potential Probiotic Candidates Isolated from Traditional Fermented Korean Foods in Stimulating Immunoglobulin A Secretion

The aim of this study was to evaluate efficacies of selected lactic acid bacteria (LAB) in inducing immunoglobulin A (IgA) secretion. Twenty-five different LAB isolated from traditional fermented Korean foods were characterized for their probiotic properties and screened to identify those that could stimulate lamina propria cells (LPCs) from Peyer's patch to secret IgA in vitro. Among them, four strains (Lactiplantibacillus plantarum CJW55-10, Lactiplantibacillus pentosus CJW18-6, L. pentosus CJW56-11, and Pediococcus acidilactici CJN2696) were found to be strong IgA inducers. The number of IgA positive B cells and soluble IgA level were increased when LPCs were co-cultured with these LAB. Expression levels of toll-like receptor (TLR) such as TLR2 and TLR4 and secretion of interleuckin-6 were augmented in LPCs treated with these LAB. Further, we determined whether oral intake of these LAB enhanced IgA production in vivo. After one-week of daily oral administration, these LAB feed mice increased mucosal IgA and serum IgA. In conclusion, selected strains of LAB could induce systemic IgA secretion by activating lamina propria B cells in Peyer's patch and oral intake of selected strains of LAB can enhance systemic immunity by inducing mucosal IgA secretion.

Novel Strategy for Alzheimer’s Disease Treatment through Oral Vaccine Therapy with Amyloid Beta

Alzheimer’s disease (AD) is a neuropathology characterized by progressive cognitive impairment and dementia. The disease is attributed to senile plaques, which are aggregates of amyloid beta (Aβ) outside nerve cells; neurofibrillary tangles, which are filamentous accumulations of phosphorylated tau in nerve cells; and loss of neurons in the brain tissue. Immunization of an AD mouse model with Aβ-eliminated pre-existing senile plaque amyloids and prevented new accumulation. Furthermore, its effect showed that cognitive function can be improved by passive immunity without side effects, such as lymphocyte infiltration in AD model mice treated with vaccine therapy, indicating the possibility of vaccine therapy for AD. Further, considering the possibility of side effects due to direct administration of Aβ, the practical use of the safe oral vaccine, which expressed Aβ in plants, is expected. Indeed, administration of this oral vaccine to Alzheimer’s model mice reduced Aβ accumulation in the brain. Moreover, almost no expression of inflammatory IgG was observed. Therefore, vaccination prior to Aβ accumulation or at an early stage of accumulation may prevent Aβ from causing AD.

Biological Clock and Inflammatory Bowel Disease Review: From the Standpoint of the Intestinal Barrier

Inflammatory bowel disease is a group of chronic, recurrent, nonspecific inflammatory diseases of the intestine that severely affect the quality of life of patients. The pathogenesis of this disease is caused by complex and interactive neural networks composed of factors such as genetic susceptibility, external environment, immune disorders, and intestinal barrier dysfunction. It is well known that there is a strong link between environmental stressors (also known as circadian clocks) that can influence circadian changes and inflammatory bowel disease. Among them, the biological clock is involved in the pathogenesis of inflammatory bowel disease by affecting the function of the intestinal barrier. Therefore, this review is aimed at systematically summarizing the latest research progress on the role of the circadian clock in the pathogenesis of inflammatory bowel disease by affecting intestinal barrier functions (intestinal mechanical barrier, intestinal immune barrier, intestinal microecological barrier, and intestinal chemical barrier) and the potential clinical value of clock genes in the management of inflammatory bowel disease, for the application of circadian clock therapy in the management of inflammatory bowel disease and then the benefit to the majority of patients.