Probiotic Interventions Alleviate Food Allergy Symptoms Correlated With Cesarean Section: A Murine Model

The roles of gut microbiome and metabolites associated with skin photoaging in mice by intestinal flora sequencing and metabolomics

Photoaging of skin, a chronic disease, can produce the appearance changes and cancer lesions of skin. Therefore, it is of great significance to investigate the mechanisms and explore effective methods to treat the disorder. Gut microbiota and intestinal metabolisms have critical roles in a variety of diseases. However, their roles on photoaging of skin were not well tested. In the present work, the results showed that compared with control group, the levels of MDA, SOD and CAT associated with oxidative stress, the levels of COL I, CER, and HA associated with skin function, and the mRNA levels of IL-1β, IL-6, TNF-α associated with inflammation after long-term exposure to ultraviolet radiation in mice were significantly changed. Skin pathological tissue was also seriously damaged. The protein levels of AQP3 and FLG were significantly decreased. Ultraviolet exposure also promoted skin photoaging by activating TNFR1/TRAF2-mediated MAPK pathway, in which the protein levels of P38/P-P38, c-FOS/P-c-FOS, MMP1, TNFR1 and TRAF2 were significantly increased in model mice compared with control group. In fecal microbiota transplantation (FMT) experiment, we found that the intestinal microbiome of control mice alleviated skin photoaging via adjusting the protein levels of P38/P-P38, c-FOS/P-c-FOS, MMP1, TNFR1 and TRAF2. 16S rRNA sequencing found that 1639 intestinal bacteria were found, in which 15 bacteria including norank_f_Ruminococcaceae, Lachnospirac -eae_NK4A136_group, Lachnoclostridium, etc., were significantly different at the genus level. Untargeted GC-TOF/MS and UHPLC-MS/MS metabolomics showed 72 and 188 metabolites including taurine, ornithine, L-arginine, L-histidine, sucrose with significant differences compared with control group. Then, amino acid targeting assay showed 10 amino acids including L-ornithine, L-arginine and L-citrulline with higher levels in control group compared with model group. In addition, we also found that the variation of Lachnoclostridium abundance may regulate L-arginine metabolism to affect skin photoaging. Some intestinal bacteria and metabolites including amino acids may be closely related to skin photoaging, which should provide new methods to treat skin photoaging in the future.

Sialic acid-based probiotic intervention in lactating mothers improves the neonatal gut microbiota and immune responses by regulating sialylated milk oligosaccharide synthesis via the gut-breast axis

Human milk oligosaccharides (HMOs) are vital milk carbohydrates that help promote the microbiota-dependent growth and immunity of infants. Sialic acid (SA) is a crucial component of sialylated milk oligosaccharides (S-MOs); however, the effects of SA supplementation in lactating mothers on S-MO biosynthesis and their breastfed infants are unknown. Probiotic intervention during pregnancy or lactation demonstrates promise for modulating the milk glycobiome. Here, we evaluated whether SA and a probiotic (Pro) mixture could increase S-MO synthesis in lactating mothers and promote the microbiota development of their breastfed neonates. The results showed that SA+Pro intervention modulated the gut microbiota and 6'-SL contents in milk of maternal rats more than the SA intervention, which promoted Lactobacillus reuteri colonization in neonates and immune development. Deficient 6'-SL in the maternal rat milk of St6gal1 knockouts (St6gal1-/-) disturbed intestinal microbial structures in their offspring, thereby impeding immune tolerance development. SA+Pro intervention in lactating St6gal1± rats compromised the allergic responses of neonates by promoting 6'-SL synthesis and the neonatal gut microbiota. Our findings from human mammary epithelial cells (MCF-10A) indicated that the GPR41-PI3K-Akt-PPAR pathway helped regulate 6'-SL synthesis in mammary glands after SA+Pro intervention through the gut - breast axis. We further validated our findings using a human-cohort study, confirming that providing SA+Pro to lactating Chinese mothers increased S-MO contents in their breast milk and promoted gut Bifidobacterium spp. and Lactobacillus spp. colonization in infants, which may help enhance immune responses. Collectively, our findings may help alter the routine supplementation practices of lactating mothers to modulate milk HMOs and promote the development of early-life gut microbiota and immunity.

The Role of Gut Microbiota and Leaky Gut in the Pathogenesis of Food Allergy

Food allergy (FA) is a growing public health concern, with an increasing prevalence in Western countries. Increasing evidence suggests that the balance of human gut microbiota and the integrity of our intestinal barrier may play roles in the development of FA. Environmental factors, including industrialization and consumption of highly processed food, can contribute to altering the gut microbiota and the intestinal barrier, increasing the susceptibility to allergic sensitization. Compositional and functional alterations to the gut microbiome have also been associated with FA. In addition, increased permeability of the gut barrier allows the translocation of allergenic molecules, triggering Th2 immune responses. Preclinical and clinical studies have highlighted the potential of probiotics, prebiotics, and postbiotics in the prevention and treatment of FA through enhancing gut barrier function and promoting the restoration of healthy gut microbiota. Finally, fecal microbiota transplantation (FMT) is now being explored as a promising therapeutic strategy to prevent FA in both experimental and clinical studies. In this review article, we aim to explore the complex interplay between intestinal permeability and gut microbiota in the development of FA, as well as depict potential therapeutic strategies.

Alterations of milk oligosaccharides in mothers with gestational diabetes mellitus impede colonization of beneficial bacteria and development of RORγt+ Treg cell-mediated immune tolerance in neonates

Gestational diabetes mellitus (GDM) is an increasing public health concern that significantly increases the risk of early childhood allergic diseases. Altered maternal milk glycobiome may strongly affect gut microbiota and enteric-specific Treg cell-mediated development of immune tolerance in GDM infants. In this study, we found that, compared with healthy Chinese mothers, mothers with GDM had significantly lower levels of total and specific human milk oligosaccharides (HMOs) in their colostrum that subsequently increased with extension of lactation. This alteration in HMO profiles significantly delayed colonization of Lactobacillus and Bifidobacterium spp. in their breast-fed infants, resulting in a distinct gut microbial structure and metabolome. Further experiments in GDM mouse models indicated that decreased contents of milk oligosaccharides, mainly 3'-sialyllactose (3'-SL), in GDM maternal mice reduced colonization of bacteria, such as L. reuteri and L. johnsonii, in the neonatal gut, which impeded development of RORγt+ regulatory T (Treg) cell-mediated immune tolerance. Treatment of GDM neonates with 3'-SL, Lactobacillus reuteri (L. reuteri) and L. johnsonii promoted the proliferation of enteric Treg cells and expression of transcription factor RORγt, which may have contributed to compromising ovalbumin (OVA)-induced allergic responses. In vitro experiments showed that 3'-SL, metabolites of L. johnsonii, and lysates of L. reuteri stimulated differentiation of mouse RORγt+ Treg cells through multiple regulatory effects on Toll-like receptor, MAPK, p53, and NOD-like receptor signaling pathways. This study provides new ideas for the development of gut microbiota and immune tolerance in GDM newborns.

Lactobacillus-derived indole-3-lactic acid ameliorates colitis in cesarean-born offspring via activation of aryl hydrocarbon receptor

Cesarean section (CS) delivery is known to disrupt the transmission of maternal microbiota to offspring, leading to an increased risk of inflammatory bowel disease (IBD). However, the underlying mechanisms remain poorly characterized. Here, we demonstrate that CS birth renders mice susceptible to dextran sulfate sodium (DSS)-induced colitis and impairs group 3 innate lymphoid cell (ILC3) development. Additionally, CS induces a sustained decrease in Lactobacillus abundance, which subsequently contributes to the colitis progression and ILC3 deficiency. Supplementation with a probiotic strain, L. acidophilus, or its metabolite, indole-3-lactic acid (ILA), can attenuate intestinal inflammation and restore ILC3 frequency and interleukin (IL)-22 level in CS offspring. Mechanistically, we indicate that ILA activates ILC3 through the aryl hydrocarbon receptor (AhR) signaling. Overall, our findings uncover a detrimental role of CS-induced gut dysbiosis in the pathogenesis of colitis and suggest L. acidophilus and ILA as potential targets to re-establish intestinal homeostasis in CS offspring.

Probiotics and the Potential of Genetic Modification as a Possible Treatment for Food Allergy

Food allergy is a common condition that affects millions of people worldwide. It is caused by an abnormal immune response to harmless food antigens, which is influenced by genetics and environmental factors. Modulating the gut microbiota and immune system with probiotics or genetically modified probiotics confers health benefits to the host and offers a novel strategy for preventing and treating food allergy. This systematic review aims to summarize the current proof of the role of probiotics in food allergy and propose a promising future research direction of using probiotics as a possible strategy of treatment for food allergy.

Do advanced glycation end products contribute to food allergy?

Sugars can bind non-enzymatically to proteins, nucleic acids or lipids and form compounds called Advanced Glycation End Products (AGEs). Although AGEs can form in vivo, factors in the Western diet such as high amounts of added sugars, processing methods such as dehydration of proteins, high temperature sterilisation to extend shelf life, and cooking methods such as frying and microwaving (and reheating), can lead to inordinate levels of dietary AGEs. Dietary AGEs (dAGEs) have the capacity to bind to the Receptor for Advanced Glycation End Products (RAGE) which is part of the endogenous threat detection network. There are persuasive epidemiological and biochemical arguments that correlate the rise in food allergy in several Western countries with increases in dAGEs. The increased consumption of dAGEs is enmeshed in current theories of the aetiology of food allergy which will be discussed.

Cordyceps militaris polysaccharide alleviates diabetic symptoms by regulating gut microbiota against TLR4/NF-κB pathway

The relationship between gut microbiota and type 2 diabetes mellitus (T2DM) has attracted increasing attention. In our work, one purified fraction a (AEPSa) was obtained from Cordyceps militaris polysaccharides, and its hypoglycemic activity and underlying mechanisms were investigated in high-fat diet (HFD)- and streptozotocin (STZ)-induced T2DM mice. The results revealed that AEPSa reshaped gut microbiota by increasing Allobaculum, Alistipes, Lachnospiraceae_NK4A136_group and norank_f_Muribaculaceae and decreasing Enterococcus and Ruminococcus_torques_group to inhibit the colonic toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway and upregulate intestinal tight junction protein expression, thereby improving glucose and serum lipid metabolism, hormone secretion and complications. Fecal microbiota transplantation (FMT) also confirmed these findings. These results indicated that symptomatic relief of T2DM might be related to AEPSa regulating the gut microbiota against the TLR4/NF-κB pathway to protect the intestinal barrier. Therefore, AEPSa might be developed as a prebiotic agent against T2DM by regulating gut microbiota.

Gut microbiome modulation by probiotics, prebiotics, synbiotics and postbiotics: a novel strategy in food allergy prevention and treatment

Food allergy has caused lots of global public health issues, particularly in developed countries. Presently, gut microbiota has been widely studied on allergy, while the role of dysbiosis in food allergy remains unknown. Scientists found that changes in gut microbial compositions and functions are strongly associated with a dramatic increase in the prevalence of food allergy. Altering microbial composition is crucial in modulating food antigens' immunogenicity. Thus, the potential roles of probiotics, prebiotics, synbiotics, and postbiotics in affecting gut bacteria communities and the immune system, as innovative strategies against food allergy, begins to attract high attention of scientists. This review briefly summarized the mechanisms of food allergy and discussed the role of the gut microbiota and the use of probiotics, prebiotics, synbiotics, and postbiotics as novel therapies for the prevention and treatment of food allergy. The perspective studies on the development of novel immunotherapy in food allergy were also described. A better understanding of these mechanisms will facilitate the development of preventive and therapeutic strategies for food allergy.

Strategies for the Identification and Assessment of Bacterial Strains with Specific Probiotic Traits

Early in the 1900s, it was proposed that health could be improved and senility delayed by manipulating gut microbiota with the host-friendly bacteria found in yogurt. Later, in 1990, the medical community reconsidered this idea and today probiotics represent a developed area of research with a billion-dollar global industry. As a result, in recent decades, increased attention has been paid to the isolation and characterization of novel probiotic bacteria from fermented foods and dairy products. Most of the identified probiotic strains belong to the lactic acid bacteria group and the genus Bifidobacterium. However, current molecular-based knowledge has allowed the identification and culture of obligatory anaerobic commensal bacteria from the human gut, such as Akkermansia spp. and Faecalibacterium spp., among other human symbionts. We are aware that the identification of new strains of these species does not guarantee their probiotic effects and that each effect must be proved through in vitro and in vivo preclinical studies before clinical trials (before even considering it as a probiotic strain). In most cases, the identification and characterization of new probiotic strain candidates may lack the appropriate set of in vitro experiments allowing the next assessment steps. Here, we address some innovative strategies reported in the literature as alternatives to classical characterization: (i) identification of alternatives using whole-metagenome shotgun sequencing, metabolomics, and multi-omics analysis; and (ii) probiotic characterization based on molecular effectors and/or traits to target specific diseases (i.e., inflammatory bowel diseases, colorectal cancer, allergies, among others).