Reversible microbial colonization of germ-free mice reveals the dynamics of IgA immune responses

Impact of afatinib on intestinal and salivary IgA: Immune response alterations linked to gastrointestinal side effects

BACKGROUND

Afatinib, an oral molecular-targeted anticancer agent, is effective but causes significant gastrointestinal side effects. These effects are associated with EGFR inhibition in intestinal cells and changes in the microbiota.

OBJECTIVE

To investigate the effects of afatinib on intestinal mucosal immunity in rats, focusing on IgA levels in the intestine and saliva, and to understand the innate and acquired immune responses to these side effects.

METHODS

Male Wistar rats received afatinib (5.2 mg/kg) daily for 24 h (Day 1) and for 2 weeks (Day 14). Gene expression in the intestine was analyzed using quantitative polymerase chain reaction. IgA levels in the intestine and saliva were measured using enzyme-linked immunosorbent assay.

RESULTS

Afatinib suppressed α-defensin 5 and pIgR in the jejunum and ileum, indicating reduced innate immunity. It increased IgA levels in the intestine and saliva, suggesting altered acquired immunity. Salivary IgA levels significantly correlated with intestinal IgA levels.

CONCLUSIONS

Afatinib affects gastrointestinal mucosal immunity, suppresses innate defense, and alters IgA production. Salivary IgA could serve as a marker for monitoring these effects, aiding cancer therapy management.

Commensal resilience: ancient ecological lessons for the modern microbiota

The gut microbiota constitutes a complex ecosystem essential for host health, offering metabolic support, modulating the immune system, and protecting against pathogens. However, this community faces constant destabilizing challenges, including dietary changes, antibiotics, and enteric infection. Prolonged microbiota imbalance or dysbiosis can exacerbate intestinal disease states, including inflammatory bowel disease and colorectal cancer. Understanding the mechanisms that sustain microbiota resilience in the face of these imbalances is crucial for maintaining host health and developing effective therapeutics. This review explores microbiota resilience through the lens of an ecological model, emphasizing the interplay between microbial communities and host-driven environmental controls. We highlight two critical factors shaping microbiota resilience: oxygen tension and iron availability-challenges encountered by ancient anaerobic organisms during early evolutionary history, from which the predominant members of the microbiota have descended. Disruptions in intestinal anaerobiosis during inflammation increase luminal oxygen levels, favoring pro-inflammatory facultative anaerobes and depleting obligately anaerobic commensals. Simultaneously, host nutritional immunity restricts iron availability, further challenging commensal survival. This dual environmental challenge of rising oxygen tension and reduced iron availability is a convergent outcome of a diverse array of perturbations, from pathogen invasion to antibiotic treatment. By highlighting these conserved downstream environmental challenges rather than the specific upstream perturbations, this ecological view offers a focused framework for understanding microbiota resilience. This perspective not only enhances our understanding of host-microbiota interactions but also informs therapeutic strategies to foster resilience and support host health.

Intestinal D-amino acids content is highly related to intestinal IgA production upon soluble dietary fiber ingestion in mice

Soluble dietary fiber (SDF) induces intestinal IgA production. Mechanistically, this has primarily been explained by intestinal bacteria producing short-chain fatty acids (SCFAs) as metabolites from the SDF. Here, we aimed to identify factors other than SCFAs that contribute to SDF-induced intestinal IgA production. SDF ingestion (3 % of the diet) for 9-12 weeks induced a four-fold increase in fecal IgA production in BALB/cA mice. The total SCFA concentration in the cecum tends to show a positive correlation with fecal IgA content (ρ = 0.5734, P = 0.0513), while the content of D-amino acids (D-AAs), inducers of IgA, in the cecum and colon exhibited a strongly positive correlation with the IgA content (ρ = 0.7805, P < 0.001). Bacterial flora analysis of fecal samples revealed that certain bacterial species were highly correlated with IgA production. These findings suggest that D-AAs play an important role in SDF-induced intestinal IgA production.

Nervous system-gut microbiota-immune system axis: future directions for preventing tumor

Tumor is one of the leading causes of death worldwide. The occurrence and development of tumors are related to multiple systems and factors such as the immune system, gut microbiota, and nervous system. The immune system plays a critical role in tumor development. Studies have also found that the gut microbiota can directly or indirectly affect tumorigenesis and tumor development. With increasing attention on the tumor microenvironment in recent years, the nervous system has emerged as a novel regulator of tumor development. Some tumor therapies based on the nervous system have also been tested in clinical trials. However, the nervous system can not only directly interact with tumor cells but also indirectly affect tumor development through the gut microbiota. The nervous system-mediated gut microbiota can regulate tumorigenesis, growth, invasion, and metastasis through the immune system. Here, we mainly explore the potential effects of the nervous system-gut microbiota-immune system axis on tumorigenesis and tumor development. The effects of the nervous system-gut microbiota-immune system axis on tumors involve the nervous system regulating immune cells through the gut microbiota, which can prevent tumor development. Meanwhile, the direct effects of the gut microbiota on tumors and the regulation of the immune system by the nervous system, which can affect tumor development, are also reviewed.

Exploring the Mucosal Immune Response in Axial Spondyloarthritis Through Immunoglobulin A-Coated Microbiota

In this review, we focus on the mucosal immune response through Immunoglobulin A (IgA)-coated microbes and their role in gut dysbiosis in axial spondyloarthritis (axSpA) and associated inflammatory bowel disease. IgA-coated microbes contribute significantly to the microbial dysbiosis observed in axSpA, potentially driving gut inflammation and translocating outside of the gut and initiating systemic immune activation, thus contributing to disease pathogenesis. These insights will provide new avenues for understanding and treating axSpA and other immune-mediated inflammatory disorders by targeting specific host immune-microbe interactions.

A type 1 immune-stromal cell network mediates disease tolerance against intestinal infection

Type 1 immunity mediates host defense through pathogen elimination, but whether this pathway also impacts tissue function is unknown. Here, we demonstrate that rapid induction of interferon γ (IFNγ) signaling coordinates a multicellular response that is critical to limit tissue damage and maintain gut motility following infection of mice with a tissue-invasive helminth. IFNγ production is initiated by antigen-independent activation of lamina propria CD8+ T cells following MyD88-dependent recognition of the microbiota during helminth-induced barrier invasion. IFNγ acted directly on intestinal stromal cells to recruit neutrophils that limited parasite-induced tissue injury. IFNγ sensing also limited the expansion of smooth muscle actin-expressing cells to prevent pathological gut dysmotility. Importantly, this tissue-protective response did not impact parasite burden, indicating that IFNγ supports a disease tolerance defense strategy. Our results have important implications for managing the pathophysiological sequelae of post-infectious gut dysfunction and chronic inflammatory diseases associated with stromal remodeling.

Cross-species immune activation and immunobiotics: a new frontier in vector-borne pathogen control

The persistent global burden of vector-borne diseases (VBDs) needs innovative control strategies, as traditional methods are compromised by acaricides and drug resistance and variable vaccine efficacy. We propose a dual-action strategy using cross-species immune activation: human microbiota triggers the production of natural antibodies that directly target pathogens in the host and modulate vector immunity by interacting with vector microbiota. The human microbiota also modulates cytokine responses, enhancing immune defenses in both host and vector. These mechanisms can be further optimized by identifying immunobiotics - specific gut microbes that stimulate protective immune responses against VBDs. This approach offers a sustainable framework to bridge the gap between host and vector immunity, introducing a novel method to combat VBDs.

Evolution of Escherichia coli strains under competent or compromised adaptive immunity

Escherichia coli is a commensal of the intestine of most mammals, but also an important human pathogen. Within a healthy human its population structure is highly dynamic, where typically a dominant E. coli strain is accompanied by several low abundance satellite strains. However, the factors underlying E. coli strain dynamics and evolution within hosts are still poorly understood. Here, we colonised germ-free immune-competent (wild-type) or immune-compromised (Rag2KO) mice, with two phylogenetically distinct strains of E. coli, to determine if strain co-existence and within-strain evolution are shaped by the adaptive immune system. Irrespectively of the immune status of the mice one strain reaches a 100-fold larger abundance than the other. However, the abundance of the dominant strain is significantly higher in Rag2KO mice. Strains co-exist for thousands of generations and accumulate beneficial mutations in genes coding for different resource preferences. A higher rate of mutation accumulation in immune-compromised vs. immune-competent mice is observed and adaptative mutations specific to immune-competent mice are identified. Importantly, the presence of the adaptive immune system selects for mutations that increase stress resistance and the dynamics of such evolutionary events associates with the onset of an antibody response.

Innate immune system signaling and intestinal dendritic cells migration to the brain underlie behavioral changes after microbial colonization in adult mice

BACKGROUND AND AIMS

Accumulating evidence suggests the microbiota is a key factor in Disorders of Gut-Brain Interaction (DGBI), by affecting host immune and neural systems. However, the underlying mechanisms remain elusive due to their complexity and clinical heterogeneity of patients with DGBIs. We aimed to identify neuroimmune pathways that are critical in microbiota-gut-brain communication during de novo gut colonization.

METHODS

We employed a combination of gnotobiotic and state-of-the-art microbial tools, behavioral analysis, immune and pharmacological approaches. Germ-free wild type, TLR signaling-deficient MyD88-/- Ticam1-/- and lymphocyte-deficient SCID mice were studied before and after colonization with specific pathogen-free microbiota, Altered Schaedler Flora, E. coli or S. typhimurium (permanent or transient colonizers). TLR agonists and antagonists, CCR7 antagonist or immunomodulators were used to study immune pathways. We assessed brain c-Fos, brain-derived neurotrophic factor, and dendritic and glial cells by immunofluorescence, expression of neuroimmune genes by NanoString and performed brain proteomics.

RESULTS

Bacterial monocolonization, conventionalization or administration of microbial products to germ-free mice altered mouse behavior similarly, acting through Toll-like receptor or nucleotide-binding oligomerization domain signaling. The process required CD11b+CD11c+CD103+ dendritic cell activation and migration into the brain. The change in behavior did not require the continued presence of bacteria and was associated with activation of multiple neuro-immune networks in the gut and the brain.

CONCLUSIONS

Changes in neural plasticity occur rapidly upon initial gut microbial colonization and involve innate immune signaling to the brain, mediated by CD11b+CD11c+CD103+ dendritic cell migration. The results identify a new target with therapeutic potential for DGBIs developing in context of increased gut and blood-brain barrier permeability.

The impact of novel probiotics isolated from the human gut on the gut microbiota and health

The gut microbiota plays a pivotal role in influencing the metabolism and immune responses of the body. A balanced microbial composition promotes metabolic health through various mechanisms, including the production of beneficial metabolites, which help regulate inflammation and support immune functions. In contrast, imbalance in the gut microbiota, known as dysbiosis, can disrupt metabolic processes and increase the risk of developing diseases, such as obesity, type 2 diabetes, and inflammatory disorders. The composition of the gut microbiota is dynamic and can be influenced by environmental factors such as diet, medication, and the consumption of live bacteria. Since the early 1900s, bacteria isolated from food and have been used as probiotics. However, the human gut also offers an enormous reservoir of bacterial strains, and recent advances in microbiota research have led to the discovery of strains with probiotic potentials. These strains, derived from a broad spectrum of microbial taxa, differ in their ecological properties and how they interact with their hosts. For most probiotics bacterial structural components and metabolites, such as short-chain fatty acids, contribute to the maintenance of metabolic and immunological homeostasis by regulating inflammation and reinforcing gut barrier integrity. Metabolites produced by probiotic strains can also be used for bacterial cross-feeding to promote a balanced microbiota. Despite the challenges related to safety, stability, and strain-specific properties, several newly identified strains offer great potential for personalized probiotic interventions, allowing for targeted health strategies.

Intestinal mucosal immunity and type 1 diabetes: Non-negligible communication between gut and pancreas

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by T cell-mediated pancreatic β cell loss, resulting in lifelong absolute insulin deficiency and hyperglycaemia. Environmental factors are recognized as a key contributor to the development of T1D, with the gut serving as a primary interface for environmental stimuli. Recent studies have revealed that the alterations in the intestinal microenvironment profoundly affect host immune responses, contributing to the aetiology and pathogenesis of T1D. However, the dominant intestinal immune cells and the underlying mechanisms remain incompletely elucidated. In this review, we provide an overview of the possible mechanisms of the intestinal mucosal system that underpin the pathogenesis of T1D, shedding light on the roles of both non-classical and classical immune cells in T1D. Our goal is to gain insights into how modulating these immune components may hold potential implications for T1D prevention and provide novel perspectives for immune-mediated therapy.

A guide to germ-free and gnotobiotic mouse technology to study health and disease

The intestinal microbiota has major influence on human physiology and modulates health and disease. Complex host-microbe interactions regulate various homeostatic processes, including metabolism and immune function, while disturbances in microbiota composition (dysbiosis) are associated with a plethora of human diseases and are believed to modulate disease initiation, progression and therapy response. The vast complexity of the human microbiota and its metabolic output represents a great challenge in unraveling the molecular basis of host-microbe interactions in specific physiological contexts. To increase our understanding of these interactions, functional microbiota research using animal models in a reductionistic setting are essential. In the dynamic landscape of gut microbiota research, the use of germ-free and gnotobiotic mouse technology, in which causal disease-driving mechanisms can be dissected, represents a pivotal investigative tool for functional microbiota research in health and disease, in which causal disease-driving mechanisms can be dissected. A better understanding of the health-modulating functions of the microbiota opens perspectives for improved therapies in many diseases. In this review, we discuss practical considerations for the design and execution of germ-free and gnotobiotic experiments, including considerations around germ-free rederivation and housing conditions, route and timing of microbial administration, and dosing protocols. This comprehensive overview aims to provide researchers with valuable insights for improved experimental design in the field of functional microbiota research.

Correlation between gut microbiota dysbiosis, metabolic syndrome and breast cancer

Breast cancer is a widespread cancer with a high death rate globally. The incidence of breast cancer is expected to increase, particularly in low and middle-income countries due to environmental factors and lifestyle changes. Several risk factors, such as age, family history, hormonal and reproductive factors, have been identified to influence breast cancer development. Metabolic syndrome, is a metabolic disorder that has also been linked to breast cancer risk. The gut microbiome has been suggested as one of the environmental factors leading to breast cancer. The human microbiome is mainly colonized in the intestine by various bacterial species, including Lactobacillus, Bifidobacterium, and Streptococcus and protect the host against pathogenic microorganisms and regulate the immune system. This study included 50 female breast cancer patients and 50 healthy controls with matched ages. Stool fresh samples were taken from test and control groups and stored at - 20 °C until further investigations. DNA of the bacteria in stool samples was extracted using reverse transcription-quantitative polymerase chain reaction to check for the bacterial 16s rRNA gene. The exclusion criteria included other malignancies, recent intestinal surgery, infectious diarrhea, prolonged use of antibiotics, substance addiction, and pregnancy or lactation. Our findings exhibited that breast cancer patients had a higher incidence of metabolic syndrome (60%) compared to cancer-free controls (40%). Furthermore, breast cancer patients had significantly lower Bifidobacterium and Lactobacillus counts than the controls. No significant difference was found in Streptococcus counts between groups. These findings support the relationship between breast cancer and metabolic syndrome and suggest the potential involvement of Lactobacillus and Bifidobacterium in breast cancer pathophysiology. Our study supports the relation between breast cancer and disorder of metabolic syndrome and suggests the potential involvement of Lactobacillus and Bifidobacterium in breast cancer pathophysiology. Further research is necessary to investigate the complex interactions between genes, the environment, and the gut microbiome in breast cancer development. Understanding these interactions could lead to the progress of novel strategies for breast cancer prevention and treatment.

The essential role of prebiotics in restoring gut health in long COVID

The gut microbiota (GM) plays an essential role in human health, influencing not only digestive processes but also the immune system´s functionality. The COVID-19 pandemic has highlighted the complex interaction between viral infections and the GM. Emerging evidence has demonstrated that SARS-CoV-2 can disrupt microbial homeostasis, leading to dysbiosis and compromised immune responses. The severity of COVID-19 has been associated with a reduction in the abundance of several beneficial bacteria in the gut. It has been proposed that consuming probiotics may help to re-colonize the GM. Although probiotics are important, prebiotics are essential for their metabolism, growth, and re-colonization capabilities. This chapter delves into the critical role of prebiotics in restoring GM after COVID-19 disease. The mechanisms by which prebiotics enhance the metabolism of beneficial bacteria will be described, and how prebiotics mediate the re-colonization of the gut with beneficial bacteria, thereby restoring microbial diversity and promoting the resilience of the gut-associated immune system. The benefits of consuming prebiotics from natural sources are superior to those from chemically purified commercial products.

Integrating gut and IgA-coated microbiota to identify Blautia as a probiotic for enhancing feed efficiency in chickens

This study explores the role of IgA-coated bacteria in improving feed efficiency in chickens, offering a novel perspective for probiotic screening. Chickens with high feed efficiency were found to have a greater abundance of Gram-positive bacteria, while low feed efficiency chickens exhibited higher levels of Gram-negative bacteria and potential pathogens. Through fecal microbiota transplantation (FMT) and integrating analysis of cecal and IgA-coated microbiota, we precisely identified Blautia as a key genus linked to improved feed efficiency. Further validation demonstrated that Blautia coccoides, a representative species of this genus, enhances feed efficiency and activates B cells to produce Immunoglobulin A (IgA), both in vivo and in vitro. Our findings provide new insights into the potential of IgA-coated bacteria as functional probiotics, offering a promising strategy for enhancing feed efficiency in animal production.

The Geometric Framework for Nutrition and Its Application to Rodent Models

Rodents have been the primary model for mammalian nutritional physiology for decades. Despite an extensive body of literature, controversies remain around the effects of specific nutrients and total energy intake on several aspects of nutritional biology, even in this well-studied model. One approach that is helping to bring clarity to the field is the geometric framework for nutrition (GFN). The GFN is a multidimensional paradigm that can be used to conceptualize nutrition and nutritional effects, design experiments, and interpret results. To date, more than 30 publications have applied the GFN to data from rodent models of nutrition. Here we review the major conclusions from these studies. We pay particular attention to the effects of macronutrients on satiety, glucose metabolism, lifespan and the biology of aging, reproductive function, immune function, and the microbiome. We finish by highlighting several knowledge gaps that became evident upon reviewing this literature.

Systematic evaluation of intratumoral and peripheral BCR repertoires in three cancers

The current understanding of humoral immune response in cancer patients suggests that tumors may be infiltrated with diffuse B cells of extra-tumoral origin or may develop organized lymphoid structures, where somatic hypermutation and antigen-driven selection occur locally. These processes are believed to be significantly influenced by the tumor microenvironment through secretory factors and biased cell-cell interactions. To explore the manifestation of this influence, we used deep unbiased immunoglobulin profiling and systematically characterized the relationships between B cells in circulation, draining lymph nodes (draining LNs), and tumors in 14 patients with three human cancers. We demonstrated that draining LNs are differentially involved in the interaction with the tumor site, and that significant heterogeneity exists even between different parts of a single lymph node (LN). Next, we confirmed and elaborated upon previous observations regarding intratumoral immunoglobulin heterogeneity. We identified B cell receptor (BCR) clonotypes that were expanded in tumors relative to draining LNs and blood and observed that these tumor-expanded clonotypes were less hypermutated than non-expanded (ubiquitous) clonotypes. Furthermore, we observed a shift in the properties of complementarity-determining region 3 of the BCR heavy chain (CDR-H3) towards less mature and less specific BCR repertoire in tumor-infiltrating B-cells compared to circulating B-cells, which may indicate less stringent control for antibody-producing B cell development in tumor microenvironment (TME). In addition, we found repertoire-level evidence that B-cells may be selected according to their CDR-H3 physicochemical properties before they activate somatic hypermutation (SHM). Altogether, our work outlines a broad picture of the differences in the tumor BCR repertoire relative to non-tumor tissues and points to the unexpected features of the SHM process.

Unveiling the Interplay Between the Human Microbiome and Gastric Cancer: A Review of the Complex Relationships and Therapeutic Avenues

The human microbiota plays a crucial role in maintaining overall health and well-being. The gut microbiota has been implicated in developing and progressing various diseases, including cancer. This review highlights the related mechanisms and the compositions that influence cancer pathogenesis with a highlight on gastric cancer. We provide a comprehensive overview of the mechanisms by which the microbiome influences cancer development, progression, and response to treatment, with a focus on identifying potential biomarkers for early detection, prevention strategies, and novel therapeutic interventions that leverage microbiome modulation. This comprehensive review can guide future research and clinical practices in understanding and harnessing the microbiome to optimize gastric cancer therapies.

Prenatal antibiotics reduce breast milk IgA and induce dysbiosis in mouse offspring, increasing neonatal susceptibility to bacterial sepsis

Antibiotics (Abx) are administered to 20%-30% of pregnant women, but their effects on neonatal immune development are poorly understood. We show that newborn mice born to Abx-treated dams are more susceptible to late-onset sepsis. This susceptibility is linked to lower maternal breast milk immunoglobulin A (IgA), neonatal fecal IgA, and IgA coating of intestinal bacteria, thus causing the translocation of intestinal pathobionts. Weaned young adults born to Abx-treated mothers had reduced IgA+ plasma cells in the ileum and colon, fecal secretory IgA (SIgA), colonic CD4+ T regulatory lymphocytes and T helper 17-like lymphocytes, and a less diverse fecal microbiome. However, treatment with apyrase, which restores SIgA secretion, prompted IgA production in breast milk and protected pups from sepsis. Additionally, breast milk from untreated mothers rescued the phenotypes of pups born to Abx-treated mothers. Our data highlight the impact of prenatal Abx on breast milk IgA and their long-term influence on intestinal mucosal immune function mediated by breastfeeding.

The protozoan commensal Tritrichomonas musculis is a natural adjuvant for mucosal IgA

Immunoglobulin (Ig) A supports mucosal immune homeostasis and host-microbiota interactions. While commensal bacteria are known for their ability to promote IgA, the role of non-bacterial commensal microbes in the induction of IgA remains elusive. Here, we demonstrate that permanent colonization with the protozoan commensal Tritrichomonas musculis (T.mu) promotes T cell-dependent, IgA class-switch recombination, and intestinal accumulation of IgA-secreting plasma cells (PC). T.mu colonization specifically drives the expansion of T follicular helper cells and a unique ICOS+ non-Tfh cell population, accompanied by an increase in germinal center B cells. Blockade of ICOS:ICOSL co-stimulation or MHCII-expression on B cells is central for the induction of IgA following colonization by T.mu, implicating a previously underappreciated mode of IgA induction following protozoan commensal colonization. Finally, T.mu further improves the induction of IgA-secreting PC specific to orally ingested antigens and their peripheral dissemination, identifying T.mu as a "natural adjuvant" for IgA. Collectively, these findings propose a protozoa-driven mode of IgA induction to support intestinal immune homeostasis.

Immunomolecular and reactivity landscapes of gut IgA subclasses in homeostasis and inflammatory bowel disease

The human gut includes plasma cells (PCs) expressing immunoglobulin A1 (IgA1) or IgA2, two structurally distinct IgA subclasses with elusive regulation, function, and reactivity. We show here that intestinal IgA1+ and IgA2+ PCs co-emerged early in life, comparably accumulated somatic mutations, and were enriched within short-lived CD19+ and long-lived CD19- PC subsets, respectively. IgA2+ PCs were extensively clonally related to IgA1+ PCs and a subset of them presumably emerged from IgA1+ precursors. Of note, secretory IgA1 (SIgA1) and SIgA2 dually coated a large fraction of mucus-embedded bacteria, including Akkermansia muciniphila. Disruption of homeostasis by inflammatory bowel disease (IBD) was associated with an increase in actively proliferating IgA1+ plasmablasts, a depletion in long-lived IgA2+ PCs, and increased SIgA1+SIgA2+ gut microbiota. Such increase featured enhanced IgA1 reactivity to pathobionts, including Escherichia coli, combined with depletion of beneficial A. muciniphila. Thus, gut IgA1 and IgA2 emerge from clonally related PCs and show unique changes in both frequency and reactivity in IBD.

Extraction and Identification of Polysaccharide from Lentinus edodes and Its Effect on Immunosuppression and Intestinal Barrier Injury Induced by Cyclophosphamide

Lentinus edodes serves as a significant source of both medicine and food, with its key component, lentinan (LNT), recognized as an effective immunomodulator. However, the mechanisms by which it regulates immune and intestinal functions under conditions of immunosuppression remain unclear. This study aims to investigate the components of lentinan and examine its potential effects on countering cyclophosphamide (CP)-induced immunosuppression, intestinal barrier damage, and dysregulation of gut microbiota. In this study, the effects of LNT were evaluated by serological indicators, histopathological changes in ileum, tight-junction-related protein expression, cytokine expression levels, and gut microbiota 16S rRNA gene sequencing. We found that LNT was effective in mitigating the abnormalities in body weight, immune organ index, and serum levels of IL-6, IL-2, IFN-γ, and IgG in mice induced by CP (p < 0.05). Furthermore, LNT demonstrated the ability to alleviate intestinal barrier damage induced by CP by increasing the mRNA levels of TNF-α, IL-1β, IFN-γ, Occludin, and ZO-1 (p < 0.05). Additionally, 16S rRNA gene sequencing revealed that LNT also normalized the disrupted abundance of Firmicutes, Proteobacteria, and Bacteroidets caused by CP. This restoration brought the gut microbiota back to normal levels and increased the abundance of certain tumor-inhibiting bacteria, such as Alistipes. Overall, lentinan demonstrated the ability to reverse the immunosuppressive effects induced by cyclophosphamide and modulate gut microbiota to restore a healthy microbial balance.

Microbe-binding Antibodies in the Female Genital Tract: Associations with the Vaginal Microbiome and Genital Immunology

Bacteria-Ig interactions maintain homeostasis in the gut through the clearance of pathogenic bacteria and the development of immune tolerance to inflammatory bacteria; whether similar interactions modulate inflammation and bacterial colonization in the female genital tract is uncertain. In this study, we used a flow cytometry-based assay to quantify microbe-binding IgA and IgG in the cervicovaginal secretions of 200 HIV-uninfected women from Nairobi, Kenya that were enriched for bacterial vaginosis. Total IgA and IgG were abundant and frequently demonstrated ex vivo binding to the key vaginal bacteria species Gardnerella vaginalis, Prevotella bivia, Lactobacillus iners, and Lactobacillus crispatus, which are largely microbe-specific. Microbe-binding Abs were generally not associated with the presence or abundance of their corresponding bacteria. Total and microbe-binding IgA and IgG were inversely correlated with total bacterial abundance and positively correlated with several proinflammatory cytokines (IL-6, TNF) and chemotactic chemokines (IP-10, MIG, MIP-1α, MIP-1β, MIP-3α, MCP-1, IL-8), independent of total bacterial abundance. Flow cytometry-based quantification of microbe-binding Abs provides a platform to investigate host-microbiota interactions in the female genital tract of human observational and interventional studies. In contrast to the gut, cervicovaginal microbe-binding IgA and IgG do not appear to be immunoregulatory but may indirectly mitigate bacteria-induced inflammation by reducing total bacterial abundance.

Probiotic Mixtures Consisting of Representatives of Bacteroidetes and Selenomonadales Increase Resistance of Newly Hatched Chicks to Salmonella Enteritidis Infection

There are extensive differences in the caecal microbiota of chicks from hatcheries and those inoculated with faecal material from adult hens. Besides differences in microbial composition, the latter chickens are highly resistant to Salmonella Enteritidis challenges, while the former are susceptible. In this study, we tested whether strains from genera Bacteroides, Megamonas, or Megasphaera can increase chicken resistance to Salmonella and Campylobacter jejuni when defined microbial mixtures consisting of these bacterial genera are administered. Mixtures consisting of different species and strains from the above-mentioned genera efficiently colonised the chicken caecum and increased chicken resistance to Salmonella by a factor of 50. The tested mixtures were even more effective in protecting chickens from Salmonella in a seeder model of infection (3-5 log reduction). The tested mixtures partially protected chickens from C. jejuni infection, though the effect was lower than that against Salmonella. The obtained data represent a first step for the development of a new type of probiotics for poultry.

Immunoglobulin secretion influences the composition of chicken caecal microbiota

The chicken caecum is colonised by hundreds of different bacterial species. Which of these are targeted by immunoglobulins and how immunoglobulin expression shapes chicken caecal microbiota has been addressed in this study. Using cell sorting followed by sequencing of V3/V4 variable region of 16S rRNA, bacterial species with increased or decreased immunoglobulin coating were determined. Next, we determined also caecal microbiota composition in immunoglobulin knockout chickens. We found that immunoglobulin coating was common and major taxa were coated with immunoglobulins. Similarly, more taxa required immunoglobulin production for caecum colonisation compared to those which became abundant in immunoglobulin-deficient chickens. Taxa with low immunoglobulin coating such as Lactobacillus, Blautia, [Eubacterium] hallii, Megamonas, Fusobacterium and Desulfovibrio all encode S-layer proteins which may reduce interactions with immunoglobulins. Although there were taxa which overgrew in Ig-deficient chickens (e.g. Akkermansia) indicating immunoglobulin production acted to exclude them from the chicken caecum, in most of the cases, immunoglobulin production more likely contributed to fixing the desired microbiota in the chicken caecum.

Transient infection of Euprymna scolopes with an engineered D-alanine auxotroph of Vibrio fischeri

The symbiosis between Vibrio fischeri and the Hawaiian bobtail squid, Euprymna scolopes, is a tractable and well-studied model of bacteria-animal mutualism. Here, we developed a method to transiently colonize E. scolopes using D-alanine (D-ala) auxotrophy of the symbiont, controlling the persistence of viable infection by supplying or withholding D-ala. We generated alanine racemase (alr) mutants of V. fischeri that lack avenues for mutational suppression of auxotrophy or reversion to prototrophy. Surprisingly, an ∆alr mutant did not require D-ala to grow in a minimal medium, a phenomenon requiring metC, which encodes cystathionine β-lyase. Likewise, overexpression of metC suppressed D-ala auxotrophy in a rich medium. To block potential mechanisms of suppression, we combined the ∆alr mutation with deletions of metC and/or bsrF, which encodes a broad-spectrum racemase and investigated the suppression rates of four D-ala auxotrophic strains. We then focused on ∆alr ∆bsrF mutant MC13, which has a suppression rate of <10-9. When D-ala was removed from a growing culture of MC13, cells rounded and lysed within 40 minutes. Transient colonization of E. scolopes was achieved by inoculating squid in seawater containing MC13 and D-ala, and then transferring the squid into water lacking D-ala, which resulted in loss of viable symbionts within hours. Interestingly, the symbionts within crypt 3 persisted longer than those of crypt 1, suggesting a difference in bacterial growth rate in distinct crypt environments. Our study highlights a new approach for inducing transient colonization and provides insight into the biogeography of the E. scolopes light organ.IMPORTANCEThe importance of this study is multi-faceted, providing a valuable methodological tool and insight into the biology of the symbiosis between Vibrio fischeri and Euprymna scolopes. First, the study sheds light on the critical role of D-ala for bacterial growth, and the underpinnings of D-ala synthesis. Our observations that metC obviates the need for D-ala supplementation of an alr mutant in minimal medium and that MetC-dependent growth correlates with D-ala in peptidoglycan, corroborate and extend previous findings in Escherichia coli regarding a role of MetC in D-ala production. Second, our isolation of robust D-ala auxotrophs led us to a novel method for studying the squid-Vibrio symbiosis, allowing for transient colonization without the use of antibiotics, and revealed intriguing differences in symbiont growth parameters in distinct light organ crypts. This work and the methodology developed will contribute to our understanding of the persistence and dynamics of V. fischeri within its host.

The immune interactions of gut glycans and microbiota in health and disease

The human digestive system harbors a vast diversity of commensal bacteria and maintains a symbiotic relationship with them. However, imbalances in the gut microbiota accompany various diseases, such as inflammatory bowel diseases (IBDs) and colorectal cancers (CRCs), which significantly impact the well-being of populations globally. Glycosylation of the mucus layer is a crucial factor that plays a critical role in maintaining the homeostatic environment in the gut. This review delves into how the gut microbiota, immune cells, and gut mucus layer work together to establish a balanced gut environment. Specifically, the role of glycosylation in regulating immune cell responses and mucus metabolism in this process is examined.

Gut microbiota dysbiosis and its impact on asthma and other lung diseases: potential therapeutic approaches

The emerging field of gut-lung axis research has revealed a complex interplay between the gut microbiota and respiratory health, particularly in asthma. This review comprehensively explored the intricate relationship between these two systems, focusing on their influence on immune responses, inflammation, and the pathogenesis of respiratory diseases. Recent studies have demonstrated that gut microbiota dysbiosis can contribute to asthma onset and exacerbation, prompting investigations into therapeutic strategies to correct this imbalance. Probiotics and prebiotics, known for their ability to modulate gut microbial compositions, were discussed as potential interventions to restore immune homeostasis. The impact of antibiotics and metabolites, including short-chain fatty acids produced by the gut microbiota, on immune regulation was examined. Fecal microbiota transplantation has shown promise in various diseases, but its role in respiratory disorders is not established. Innovative approaches, including mucus transplants, inhaled probiotics, and microencapsulation strategies, have been proposed as novel therapeutic avenues. Despite challenges, including the sophisticated adaptability of microbial communities and the need for mechanistic clarity, the potential for microbiota-based interventions is considerable. Collaboration between researchers, clinicians, and other experts is essential to unravel the complexities of the gut-lung axis, paving a way for innovative strategies that could transform the management of respiratory diseases.

Microbiome-Stealth Regulator of Breast Homeostasis and Cancer Metastasis

Cumulative evidence attests to the essential roles of commensal microbes in the physiology of hosts. Although the microbiome has been a major research subject since the time of Luis Pasteur and William Russell over 140 years ago, recent findings that certain intracellular bacteria contribute to the pathophysiology of healthy vs. diseased tissues have brought the field of the microbiome to a new era of investigation. Particularly, in the field of breast cancer research, breast-tumor-resident bacteria are now deemed to be essential players in tumor initiation and progression. This is a resurrection of Russel's bacterial cause of cancer theory, which was in fact abandoned over 100 years ago. This review will introduce some of the recent findings that exemplify the roles of breast-tumor-resident microbes in breast carcinogenesis and metastasis and provide mechanistic explanations for these phenomena. Such information would be able to justify the utility of breast-tumor-resident microbes as biomarkers for disease progression and therapeutic targets.

B cell academy of the gut: an update on gut associated germinal centre B cell dynamics

BACKGROUND

The gut is an environment in which the immune system closely interacts with a vast number of foreign antigens, both inert such as food and alive, from the viral, bacterial, fungal and protozoal microbiota. Within this environment, germinal centres, which are microanatomical structures where B cells affinity-mature, are chronically present and active.

MAIN BODY

The functional mechanism by which gut-associated germinal centres contribute to gut homeostasis is not well understood. Additionally, the role of T cells in class switching to immunoglobulin A and the importance of B cell affinity maturation in homeostasis remains elusive. Here, we provide a brief overview of the dynamics of gut-associated germinal centres, T cell dependency in Immunoglobulin A class switching, and the current state of research regarding the role of B cell selection in germinal centres in the gut under steady-state conditions in gnotobiotic mouse models and complex microbiota, as well as in response to immunization and microbial colonization. Furthermore, we briefly link those processes to immune system maturation and relevant diseases.

CONCLUSION

B cell response at mucosal surfaces consists of a delicate interplay of many dynamic factors, including the microbiota and continuous B cell influx. The rapid turnover within gut-associated germinal centres and potential influences of an early-life window of immune system imprinting complicate B cell dynamics in the gut.

Can fecal microbiota transplantations modulate autoimmune responses in type 1 diabetes?

Type 1 diabetes (T1D) is a chronic autoimmune disease targeting insulin-producing pancreatic beta cells. T1D is a multifactorial disease incorporating genetic and environmental factors. In recent years, the advances in high-throughput sequencing have allowed researchers to elucidate the changes in the gut microbiota taxonomy and functional capacity that accompany T1D development. An increasing number of studies have shown a role of the gut microbiota in mediating immune responses in health and disease, including autoimmunity. Fecal microbiota transplantations (FMT) have been largely used in murine models to prove a causal role of the gut microbiome in disease progression and have been shown to be a safe and effective treatment in inflammatory human diseases. In this review, we summarize and discuss recent research regarding the gut microbiota-host interactions in T1D, the current advancement in therapies for T1D, and the usefulness of FMT studies to explore microbiota-host immunity encounters in murine models and to shape the course of human type 1 diabetes.

An overview of early genetic predictors of IgA deficiency

INTRODUCTION

Inborn errors of immunity (IEIs) refer to a heterogeneous category of diseases with defects in the number and/or function of components of the immune system. Immunoglobulin A (IgA) deficiency is the most prevalent IEI characterized by low serum level of IgA and normal serum levels of IgG and/or IgM. Most of the individuals with IgA deficiency are asymptomatic and are only identified through routine laboratory tests. Others may experience a wide range of clinical features including mucosal infections, allergies, and malignancies as the most important features. IgA deficiency is a multi-complex disease, and the exact pathogenesis of it is still unknown.

AREAS COVERED

This review compiles recent research on genetic and epigenetic factors that may contribute to the development of IgA deficiency. These factors include defects in B-cell development, IgA class switch recombination, synthesis, secretion, and the long-term survival of IgA switched memory B cells and plasma cells.

EXPERT OPINION

A better and more comprehensive understanding of the cellular pathways involved in IgA deficiency could lead to personalized surveillance and potentially curative strategies for affected patients, especially those with severe symptoms.

The effect and potential mechanism of inulin combined with fecal microbiota transplantation on early intestinal immune function in chicks

Our previous research found that fecal microbiota transplantation (FMT) and inulin synergistically affected the intestinal barrier and immune system function in chicks. However, does it promote the early immunity of the poultry gut-associated lymphoid tissue (GALT)? How does it regulate the immunity? We evaluated immune-related indicators in the serum, cecal tonsil, and intestine to determine whether FMT synergistic inulin had a stronger impact on gut health and which gene expression regulation was affected. The results showed that FMT synergistic inulin increased TGF-β secretion and intestinal goblet cell number and MUC2 expression on day 14. Expression of BAFFR, PAX5, CXCL12, and IL-2 on day 7 and expression of CXCR4 and IL-2 on day 14 in the cecal tonsils significantly increased. The transcriptome indicated that CD28 and CTLA4 were important regulatory factors in intestinal immunity. Correlation analysis showed that differential genes were related to the immunity and development of the gut and cecal tonsil. FMT synergistic inulin promoted the development of GALT, which improved the early-stage immunity of the intestine by regulating CD28 and CTLA4. This provided new measures for replacing antibiotic use and reducing the use of therapeutic drugs while laying a technical foundation for achieving anti-antibiotic production of poultry products.

Development of systemic and mucosal immune responses against gut microbiota in early life and implications for the onset of allergies

The early microbial colonization of human mucosal surfaces is essential for the development of the host immune system. Already during pregnancy, the unborn child is prepared for the postnatal influx of commensals and pathogens via maternal antibodies, and after birth this protection is continued with antibodies in breast milk. During this critical window of time, which extends from pregnancy to the first year of life, each encounter with a microorganism can influence children's immune response and can have a lifelong impact on their life. For example, there are numerous links between the development of allergies and an altered gut microbiome. However, the exact mechanisms behind microbial influences, also extending to how viruses influence host-microbe interactions, are incompletely understood. In this review, we address the impact of infants' first microbial encounters, how the immune system develops to interact with gut microbiota, and summarize how an altered immune response could be implied in allergies.

Commensal microbiome and gastrointestinal mucosal immunity: Harmony and conflict with our closest neighbor

BACKGROUND

The gastrointestinal tract contains a wide range of microorganisms that have evolved alongside the immune system of the host. The intestinal mucosa maintains balance within the intestines by utilizing the mucosal immune system, which is controlled by the complex gut mucosal immune network.

OBJECTIVE

This review aims to comprehensively introduce current knowledge of the gut mucosal immune system, focusing on its interaction with commensal bacteria.

RESULTS

The gut mucosal immune network includes gut-associated lymphoid tissue, mucosal immune cells, cytokines, and chemokines. The connection between microbiota and the immune system occurs through the engagement of bacterial components with pattern recognition receptors found in the intestinal epithelium and antigen-presenting cells. This interaction leads to the activation of both innate and adaptive immune responses. The interaction between the microbial community and the host is vital for maintaining the balance and health of the host's mucosal system.

CONCLUSION

The gut mucosal immune network maintains a delicate equilibrium between active immunity, which defends against infections and damaging non-self antigens, and immunological tolerance, which allows for the presence of commensal microbiota and dietary antigens. This balance is crucial for the maintenance of intestinal health and homeostasis. Disturbance of gut homeostasis leads to enduring or severe gastrointestinal ailments, such as colorectal cancer and inflammatory bowel disease. Utilizing these factors can aid in the development of cutting-edge mucosal vaccines that have the ability to elicit strong protective immune responses at the primary sites of pathogen invasion.

Human milk antibodies to global pathogens reveal geographic and interindividual variations in IgA and IgG

BACKGROUNDThe use of high-throughput technologies has enabled rapid advancement in the knowledge of host immune responses to pathogens. Our objective was to compare the repertoire, protection, and maternal factors associated with human milk antibodies to infectious pathogens in different economic and geographic locations.METHODSUsing multipathogen protein microarrays, 878 milk and 94 paired serum samples collected from 695 women in 5 high and low-to-middle income countries (Bangladesh, Finland, Peru, Pakistan, and the United States) were assessed for specific IgA and IgG antibodies to 1,607 proteins from 30 enteric, respiratory, and bloodborne pathogens.RESULTSThe antibody coverage across enteric and respiratory pathogens was highest in Bangladeshi and Pakistani cohorts and lowest in the U.S. and Finland. While some pathogens induced a dominant IgA response (Campylobacter, Klebsiella, Acinetobacter, Cryptosporidium, and pertussis), others elicited both IgA and IgG antibodies in milk and serum, possibly related to the invasiveness of the infection (Shigella, enteropathogenic E. coli "EPEC", Streptococcus pneumoniae, Staphylococcus aureus, and Group B Streptococcus). Besides the differences between economic regions and decreases in concentrations over time, human milk IgA and IgG antibody concentrations were lower in mothers with high BMI and higher parity, respectively. In Bangladeshi infants, a higher specific IgA concentration in human milk was associated with delayed time to rotavirus infection, implying protective properties of antirotavirus antibodies, whereas a higher IgA antibody concentration was associated with greater incidence of Campylobacter infection.CONCLUSIONThis comprehensive assessment of human milk antibody profiles may be used to guide the development of passive protection strategies against infant morbidity and mortality.FUNDINGBill and Melinda Gates Foundation grant OPP1172222 (to KMJ); Bill and Melinda Gates Foundation grant OPP1066764 funded the MDIG trial (to DER); University of Rochester CTSI and Environmental Health Sciences Center funded the Rochester Lifestyle study (to RJL); and R01 AI043596 funded PROVIDE (to WAP).

Metabolic fitness of IgA+ plasma cells in the gut requires DOCK8

Dedicator of cytokinesis 8 (DOCK8) mutations lead to a primary immunodeficiency associated with recurrent gastrointestinal infections and poor antibody responses but, paradoxically, heightened IgE to food antigens, suggesting that DOCK8 is central to immune homeostasis in the gut. Using Dock8-deficient mice, we found that DOCK8 was necessary for mucosal IgA production to multiple T cell-dependent antigens, including peanut and cholera toxin. Yet DOCK8 was not necessary in T cells for this phenotype. Instead, B cell-intrinsic DOCK8 was required for maintenance of antigen-specific IgA-secreting plasma cells (PCs) in the gut lamina propria. Unexpectedly, DOCK8 was not required for early B cell activation, migration, or IgA class switching. An unbiased interactome screen revealed novel protein partners involved in metabolism and apoptosis. Dock8-deficient IgA+ B cells had impaired cellular respiration and failed to engage glycolysis appropriately. These results demonstrate that maintenance of the IgA+ PC compartment requires DOCK8 and suggest that gut IgA+ PCs have unique metabolic requirements for long-term survival in the lamina propria.

Advances and challenges in investigating B-cells via single-cell transcriptomics

Single-cell RNA sequencing (scRNAseq) and Variable, Diversity, Joining (VDJ) profiling have improved our understanding of B-cells. Recent scRNAseq-based approaches have led to the discovery of intermediate B-cell states, including preplasma cells and pregerminal centre B-cells, as well as unveiling protective roles for B-cells within tertiary lymphoid structures in respiratory infections and cancers. These studies have improved our understanding of transcriptional and epigenetic control of B-cell development and of atypical and memory B-cell differentiation. Advancements in temporal profiling in parallel with transcriptomic and VDJ sequencing have consolidated our understanding of the trajectory of B-cell clones over the course of infection and vaccination. Challenges remain in studying B-cell states across tissues in humans, in relating spatial location with B-cell phenotype and function, in examining antibody isotype switching events, and in unequivocal determination of clonal relationships. Nevertheless, ongoing multiomic assessments and studies of cellular interactions within tissues promise new avenues for improving humoral immunity and combatting autoimmune conditions.

Gut commensals require Peyer's patches to induce protective systemic IgA responses

Gut educated IgA secreting plasma cells that disseminate beyond the mucosa and into systemic tissues have been described as providing beneficial effects from disease in several contexts. Several bacteria have been implicated in the induction of systemic IgA, however the mechanisms that result in differential levels of induction by each bacterial species are still unknown. Here we show, the commensal bacteria, Bacteroides fragilis (Bf), is an efficient inducer of systemic IgA responses. The ability of Bf to induce the production of bone marrow IgA plasma cells and high levels of serum IgA relied on high levels of gut colonization in a dose-dependent manner. Colonization induced Bf-specific IgA responses were severely diminished in the absence of Peyer's patches, but not the murine cecal patch. Colonization of mice with Bf, a natural human commensal, resulted in few changes within the microbiome and the host transcriptional profile in the gut, suggesting a commensal relationship with the host. Bf colonization did benefit the mice by inducing systemic IgA that led to increased protection in a bowel perforation model resulting in lower peritoneal abscess formation. These findings demonstrate a critical role for bacterial colonization and Peyer's patches in the induction of robust systemic IgA responses that confer protection from bacterial dissemination outside of the gut.

Probiotics induce intestinal IgA secretion in weanling mice potentially through promoting intestinal APRIL expression and modulating the gut microbiota composition

Intestinal infections are strongly associated with infant mortality, and intestinal immunoglobulin A (IgA) is important to protect infants from intestinal infections after weaning. This study aims to screen probiotics that can promote the production of intestinal IgA after weaning and further explore their potential mechanisms of action. In this study, probiotics promoting intestinal IgA production were screened in weanling mouse models. The results showed that oral administration of Bifidobacterium bifidum (B. bifidum) FL228.1 and Bifidobacterium bifidum (B. bifidum) FL276.1 significantly enhanced IgA levels in the small intestine and upregulated the expression of a proliferation-inducing ligand (APRIL) and its upstream regulatory factor toll-like receptor 4 (TLR4). Furthermore, B. bifidum FL228.1 upregulated the relative abundance of Lactobacillus, while B. bifidum FL276.1 increased the relative abundance of Marvinbryantia and decreased Mucispirillum, further elevating intestinal IgA levels. In summary, B. bifidum FL228.1 and B. bifidum FL276.1 can induce IgA production in the intestinal tract of weanling mice by promoting intestinal APRIL expression and mediating changes in the gut microbiota, thus playing a significant role in enhancing local intestinal immunity in infants.

The gut microbiome modulates the impact of Anaerobutyricum soehngenii supplementation on glucose homeostasis in mice

Background

There is growing interest in the development of next-generation probiotics to prevent or treat metabolic syndrome. Previous studies suggested that Anaerobutyricum soehngenii may represent a promising probiotic candidate. A recent human study showed that while A. soehngenii supplementation is well tolerated and safe, it resulted in variable responses among individuals with a subset of the subjects significantly benefiting from the treatment. We hypothesized that gut microbiome variation is linked to the heterogeneous responses to A. soehngenii treatment observed in humans.

Results

We colonized germ-free mice with fecal microbiota from human subjects that responded to A. soehngenii treatment (R65 and R55) and non-responder subjects (N96 and N40). Colonized mice were fed a high-fat diet (45% kcal from fat) to induce insulin resistance, and orally treated with either live A. soehngenii culture or heat-killed culture. We found that R65-colonized mice received a benefit in glycemic control with live A. soehngenii treatment while mice colonized with microbiota from the other donors did not. The glucose homeostasis improvements observed in R65-colonized mice were positively correlated with levels of cecal propionate, an association that was reversed in N40-colonized mice. To test whether the microbiome modulates the effects of propionate, R65- or N40-colonized mice were treated with tripropionin (TP, glycerol tripropionate), a pro-drug of propionate, or glycerol (control). TP supplementation showed a similar response pattern as that observed in live A. soehngenii treatment, suggesting that propionate may mediate the effects of A. soehngenii. We also found that TP supplementation to conventional mice reduces adiposity, improves glycemic control, and reduces plasma insulin compared to control animals supplemented with glycerol.

Conclusions

These findings highlight the importance of the microbiome on glycemic control and underscore the need to better understand personal microbiome-by-therapeutic interactions to develop more effective treatment strategies.

Self-assembled nanomicelles for oral delivery of luteolin utilizing the intestinal lymphatic pathway to target pancreatic cancer

Pancreatic cancer is one of the major cause of cancer-related deaths worldwide, and is mainly associated with carcinomas of the pancreatic tissue. Current therapies for treating pancreatic cancer have a major drawback related to their low bioavailability and non-specificity, which leads to low therapeutic efficacy and side effects. Luteolin (LUT) has been clinically used for treatment of various types of cancer, although its clinical use has declined owing to its low oral bioavailability. In this work, we prepared an effervescent-based nanocarrier (NG) that rapidly triggers an effervescent reaction and transforms into nanomicelles to modulate the oral bioavailability of the hydrophobic drug Luteolin (LUT). Furthermore, we performed tests to assess its in vitro epithelial cell permeability and cellular internalization on a Caco-2 monolayer. We also performed in vivo toxicity assessment using animal models. Further, we evaluated the nanocarrier system's in vivo efficacy in tumor xenograft pancreatic cancer models. We validated that being pH responsive, our effervescent carrier disassembles at intestinal pH and is absorbed through the intestinal lymphatic system (ILS) to further site-specifically invade the pancreatic cancer cells. Furthermore, the negative surface charge and particle size (450 ± 100 nm) of the nanomicelles helped to internalize LUT through the ILS. We observed that LUT-loaded nanomicelles have significant antipancreatic cancer efficacy by activating caspase-3 activity and downregulating VEGF-A, FAK, TNF-α, and Ki-67. Unlike other drug-delivery systems, we developed noninvasive nanocarrier system has the capability of transporting the hydrophobic drug LUT from the intestine to the tumor site by utilizing the ILS.

Microbiota from human infants consuming secretors or non-secretors mothers' milk impacts the gut and immune system in mice

Maternal secretor status is one of the determinants of human milk oligosaccharides (HMOs) composition, which, in turn, influences the gut microbiota composition of infants. To understand if this change in gut microbiota impacts immune cell composition, intestinal morphology, and gene expression, 21-day-old germ-free C57BL/6 mice were transplanted with fecal microbiota from infants whose mothers were either secretors (SMM) or non-secretors (NSM) or from infants consuming dairy-based formula (MFM). For each group, one set of mice was supplemented with HMOs. HMO supplementation did not significantly impact the microbiota diversity; however, SMM mice had a higher abundance of genus Bacteroides, Bifidobacterium, and Blautia, whereas, in the NSM group, there was a higher abundance of Akkermansia, Enterocloster, and Klebsiella. In MFM, gut microbiota was represented mainly by Parabacteroides, Ruminococcaceae_unclassified, and Clostrodium_sensu_stricto. In mesenteric lymph node, Foxp3+ T cells and innate lymphoid cells type 2 were increased in MFM mice supplemented with HMOs, while in the spleen, they were increased in SMM + HMOs mice. Similarly, serum immunoglobulin A was also elevated in MFM + HMOs group. Distinct global gene expression of the gut was observed in each microbiota group, which was enhanced with HMOs supplementation. Overall, our data show that distinct infant gut microbiota due to maternal secretor status or consumption of dairy-based formula and HMO supplementation impacts immune cell composition, antibody response, and intestinal gene expression in a mouse model.

IMPORTANCE

Early life factors like neonatal diet modulate gut microbiota, which is important for the optimal gut and immune function. One such factor, human milk oligosaccharides (HMOs), the composition of which is determined by maternal secretor status, has a profound effect on infant gut microbiota. However, how the infant gut microbiota composition determined by maternal secretor status or consumption of infant formula devoid of HMOs impacts infant intestinal ammorphology, gene expression, and immune signature is not well explored. This study provides insights into the differential establishment of infant microbiota derived from infants fed by secretor or non-secretor mothers milk or those consuming infant formula and demonstrates that the secretor status of mothers promotes Bifidobacteria and Bacteroides sps. establishment. This study also shows that supplementation of pooled HMOs in mice changed immune cell composition in the spleen and mesenteric lymph nodes and immunoglobulins in circulation. Hence, this study highlights that maternal secretor status has a role in infant gut microbiota composition, and this, in turn, can impact host gut and immune system.

Biotics: An emerging food supplement for health improvement in the era of immune modulation

The involvement of the commensal microbiota in immune function is a multifold process. Biotics, such as probiotics, prebiotics, synbiotics, and paraprobiotics, have been subjected to animal and human trials demonstrating the association between gut microbes and immunity biomarkers leading to improvement in overall health. In recent years, studies on human microbiome interaction have established the multifarious role of biotics in maintaining overall health. The consumption of biotics has been extensively reported to help in maintaining microbial diversity, enhancing gut-associated mucosal immune homeostasis, and providing protection against a wide range of lifestyle disorders. However, the establishment of biotics as an alternative therapy for a range of health conditions is yet to be ascertained. Despite the fact that scientific literature has demonstrated the correlation between biotics and immune modulation, most in vivo and in vitro reports are inconclusive on the dosage required. This review provides valuable insights into the immunomodulatory effects of biotics consumption based on evidence obtained from animal models and clinical trials. Furthermore, we highlight the optimal dosages of biotics that have been reported to deliver maximum health benefits. By identifying critical research gaps, we have suggested a roadmap for future investigations to advance our understanding of the intricate crosstalk between biotics and immune homeostasis.

The gut microbiome as a modulator of arterial function and age-related arterial dysfunction

The arterial system is integral to the proper function of all other organs and tissues. Arterial function is impaired with aging, and arterial dysfunction contributes to the development of numerous age-related diseases, including cardiovascular diseases. The gut microbiome has emerged as an important regulator of both normal host physiological function and impairments in function with aging. The purpose of this review is to summarize more recently published literature demonstrating the role of the gut microbiome in supporting normal arterial development and function and in modulating arterial dysfunction with aging in the absence of overt disease. The gut microbiome can be altered due to a variety of exposures, including physiological aging processes. We explore mechanisms by which the gut microbiome may contribute to age-related arterial dysfunction, with a focus on changes in various gut microbiome-related compounds in circulation. In addition, we discuss how modulating circulating levels of these compounds may be a viable therapeutic approach for improving artery function with aging. Finally, we identify and discuss various experimental considerations and research gaps/areas of future research.

Epithelial regulation of microbiota-immune cell dynamics

The mammalian gastrointestinal tract hosts a diverse community of trillions of microorganisms, collectively termed the microbiota, which play a fundamental role in regulating tissue physiology and immunity. Recent studies have sought to dissect the cellular and molecular mechanisms mediating communication between the microbiota and host immune system. Epithelial cells line the intestine and form an initial barrier separating the microbiota from underlying immune cells, and disruption of epithelial function has been associated with various conditions ranging from infection to inflammatory bowel diseases and cancer. From several studies, it is now clear that epithelial cells integrate signals from commensal microbes. Importantly, these non-hematopoietic cells also direct regulatory mechanisms that instruct the recruitment and function of microbiota-sensitive immune cells. In this review, we discuss the central role that has emerged for epithelial cells in orchestrating intestinal immunity and highlight epithelial pathways through which the microbiota can calibrate tissue-intrinsic immune responses.

Identification of Intestinal Lamina Propria Plasma Cells by Surface Transmembrane Activator and CAML Interactor Expression

Plasma cells secrete an abundance of Abs and are a crucial component of our immune system. The intestinal lamina propria harbors the largest population of plasma cells, most of which produce IgA. These Abs can bind to beneficial gut bacteria to reinforce intestinal homeostasis and provide protection against enteric pathogens. Plasma cells downregulate many cell-surface proteins commonly used to identify B cells. In mice, expression of the surface marker CD138 has been widely used to identify plasma cells in lymph nodes, bone marrow, and spleen. Intestinal plasma cells require liberation via extensive tissue processing involving treatment with collagenase. We report that detection of CD138 surface expression is reduced following collagenase treatment. Using a mouse in which yellow fluorescent protein expression is controlled by the plasma cell requisite transcription factor Blimp-1, we show that surface detection of transmembrane activator and CAML interactor captures a significant proportion of Ab-secreting plasma cells in the intestinal lamina propria and gut-draining mesenteric lymph nodes. Additionally, we describe a flow cytometry panel based on the detection of surface markers to identify murine B cell subsets in the intestinal lamina propria and, as a proof of concept, combine it with a cutting-edge fate-tracking system to characterize the fate of germinal center B cells activated in early life. By identifying plasma cells and other key intestinal B subsets in a manner compatible with several downstream applications, including sorting and culturing and in vitro manipulations, this efficient and powerful approach can enhance studies of mucosal immunity.

Efficacy and safety of gut microbiota-based therapies in autoimmune and rheumatic diseases: a systematic review and meta-analysis of 80 randomized controlled trials

BACKGROUND

Previous randomized controlled trials (RCTs) suggested that gut microbiota-based therapies may be effective in treating autoimmune diseases, but a systematic summary is lacking.

METHODS

Pubmed, EMbase, Sinomed, and other databases were searched for RCTs related to the treatment of autoimmune diseases with probiotics from inception to June 2022. RevMan 5.4 software was used for meta-analysis after 2 investigators independently screened literature, extracted data, and assessed the risk of bias of included studies.

RESULTS

A total of 80 RCTs and 14 types of autoimmune disease [celiac sprue, SLE, and lupus nephritis (LN), RA, juvenile idiopathic arthritis (JIA), spondyloarthritis, psoriasis, fibromyalgia syndrome, MS, systemic sclerosis, type 1 diabetes mellitus (T1DM), oral lichen planus (OLP), Crohn's disease, ulcerative colitis] were included. The results showed that gut microbiota-based therapies may improve the symptoms and/or inflammatory factor of celiac sprue, SLE and LN, JIA, psoriasis, PSS, MS, systemic sclerosis, Crohn's disease, and ulcerative colitis. However, gut microbiota-based therapies may not improve the symptoms and/or inflammatory factor of spondyloarthritis and RA. Gut microbiota-based therapies may relieve the pain of fibromyalgia syndrome, but the effect on fibromyalgia impact questionnaire score is not significant. Gut microbiota-based therapies may improve HbA1c in T1DM, but its effect on total insulin requirement does not seem to be significant. These RCTs showed that probiotics did not increase the incidence of adverse events.

CONCLUSIONS

Gut microbiota-based therapies may improve several autoimmune diseases (celiac sprue, SLE and LN, JIA, psoriasis, fibromyalgia syndrome, PSS, MS, T1DM, Crohn's disease, and ulcerative colitis).

Unveiling the Immunomodulatory Potential of Phenolic Compounds in Food Allergies

Food allergies are becoming ever more prevalent around the world. This pathology is characterized by the breakdown of oral tolerance to ingested food allergens, resulting in allergic reactions in subsequent exposures. Due to the possible severity of the symptoms associated with this pathology, new approaches to prevent it and reduce associated symptoms are of utmost importance. In this framework, dietary phenolic compounds appear as a tool with a not fully explored potential. Some phenolic compounds have been pointed to with the ability to modulate food allergies and possibly reduce their symptoms. These compounds can modulate food allergies through many different mechanisms, such as altering the bioaccessibility and bioavailability of potentially immunogenic peptides, by modulating the human immune system and by modulating the composition of the human microbiome that resides in the oral cavity and the gastrointestinal tract. This review deepens the state-of-the-art of the modulation of these mechanisms by phenolic compounds. While this review shows clear evidence that dietary supplementation with foods rich in phenolic compounds might constitute a new approach to the management of food allergies, it also highlights the need for further research to delve into the mechanisms of action of these compounds and decipher systematic structure/activity relationships.