Mucus enhances gut homeostasis and oral tolerance by delivering immunoregulatory signals

Bidirectional regulation of the brain-gut-microbiota axis following traumatic brain injury

JOURNAL/nrgr/04.03/01300535-202508000-00002/figure1/v/2024-09-30T120553Z/r/image-tiff Traumatic brain injury is a prevalent disorder of the central nervous system. In addition to primary brain parenchymal damage, the enduring biological consequences of traumatic brain injury pose long-term risks for patients with traumatic brain injury; however, the underlying pathogenesis remains unclear, and effective intervention methods are lacking. Intestinal dysfunction is a significant consequence of traumatic brain injury. Being the most densely innervated peripheral tissue in the body, the gut possesses multiple pathways for the establishment of a bidirectional "brain-gut axis" with the central nervous system. The gut harbors a vast microbial community, and alterations of the gut niche contribute to the progression of traumatic brain injury and its unfavorable prognosis through neuronal, hormonal, and immune pathways. A comprehensive understanding of microbiota-mediated peripheral neuroimmunomodulation mechanisms is needed to enhance treatment strategies for traumatic brain injury and its associated complications. We comprehensively reviewed alterations in the gut microecological environment following traumatic brain injury, with a specific focus on the complex biological processes of peripheral nerves, immunity, and microbes triggered by traumatic brain injury, encompassing autonomic dysfunction, neuroendocrine disturbances, peripheral immunosuppression, increased intestinal barrier permeability, compromised responses of sensory nerves to microorganisms, and potential effector nuclei in the central nervous system influenced by gut microbiota. Additionally, we reviewed the mechanisms underlying secondary biological injury and the dynamic pathological responses that occur following injury to enhance our current understanding of how peripheral pathways impact the outcome of patients with traumatic brain injury. This review aimed to propose a conceptual model for future risk assessment of central nervous system-related diseases while elucidating novel insights into the bidirectional effects of the "brain-gut-microbiota axis."

Harnessing the human microbiome and its impact on immuno-oncology and nanotechnology for next-generation cancer therapies

The integration of microbiome research and nanotechnology represents a significant advancement in immuno-oncology, potentially improving the effectiveness of cancer immunotherapies. Recent studies highlight the influential role of the human microbiome in modulating immune responses, presenting new opportunities to enhance immune checkpoint inhibitors (ICIs) and other cancer therapies. Nanotechnology offers precise drug delivery and immune modulation capabilities, minimizing off-target effects while maximizing therapeutic outcomes. This review consolidates current knowledge on the interactions between the microbiome and the immune system, emphasizing the microbiome's impact on ICIs, and explores the incorporation of nanotechnology in cancer treatment strategies. Additionally, it provides a forward-looking perspective on the synergistic potential of microbiome modulation and nanotechnology to overcome existing challenges in immuno-oncology. This integrated approach may enhance the personalization and effectiveness of next-generation cancer treatments, paving the way for transformative patient care.

The role and implication of rotavirus VP8∗ in viral infection and vaccine development

Rotaviruses (RVs) are major causative agents of diarrhea in both humans and animals worldwide. Despite the successful development of live attenuated vaccines, the efficacy of these vaccines remains low in developing countries and RV infections still result in more than 200,000 deaths in children under 5 years old globally each year. These viruses are also an enteric pathogen for agricultural animals and have caused substantial economic losses annually to the animal livestock industry. Frequent reassortment and the emergence of new RV strains continue to pose a significant challenge to human and agricultural animal health. Attachment to susceptible cells by recognizing cell surface glycans is the first step of the RV lifecycle, which is directed by the RV spike protein VP8∗. VP8∗-host glycan receptor interactions are thought to be strain-specific and play an important role in RV replication fitness, tropism, and cross-species transmission. This review will summarize the current understanding of the roles of VP8∗ in engagement of glycan receptors and its functional consequences in impacting RV replication fitness and host ranges. The current progress towards developing a VP8∗-based RV vaccine is also discussed in the review.

Microbiota-produced immune regulatory bile acid metabolites control central nervous system autoimmunity

The commensal gut microbiota has a role in the pathogenesis of extra-intestinal autoimmune diseases such as multiple sclerosis (MS) with unknown mechanisms. Deoxycholic acid (DCA) and lithocholic acid (LCA) are secondary bile acid metabolites (BAMs) produced from primary bile acids by gut microbiota that play key immune regulatory functions by promoting FOXP3+ regulatory T (Treg) cell differentiation at the expense of Th17 cells. Here, we show that bacteria releasing enzymes responsible for secondary BAMs production are under-represented in the gut of MS patients, resulting in significantly reduced intestinal concentration of DCA and immune dysregulation with increased percentage of Th17 cells. We validated our human findings in a preclinical model of MS by showing that DCA/LCA administration prevents experimental autoimmune encephalomyelitis (EAE) by dampening Th17 cell differentiation and the effector phenotype of myelin-reactive T cells. Our data highlight the key role of immune regulatory BAMs for the prevention of central nervous system (CNS) autoimmunity.

Antigen Uptake in the Gut: An Underappreciated Piece to the Puzzle?

The mammalian gut is a vast, diverse, and dynamic single-layer epithelial surface exposed to trillions of microbes, microbial products, and the diet. Underlying this epithelium lies the largest collection of immune cells in the body; these cells encounter luminal substances to generate antigen-specific immune responses characterized by tolerance at homeostasis and inflammation during enteric infections. How the outcomes of antigen-specific tolerance and inflammation are appropriately balanced is a central question in mucosal immunology. Furthermore, how substances large enough to generate antigen-specific responses cross the epithelium and encounter the immune system in homeostasis and during inflammation remains largely unexplored. Here we discuss the challenges presented to the gut immune system, the identified pathways by which luminal substances cross the epithelium, and insights suggesting that the pathways used by substances to cross the epithelium affect the ensuing immune response.

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.

The fungal protein Lingzhi-8 ameliorates psoriasis-like dermatitis in mice through gut CD103+ tolerogenic dendritic cells, retinaldehyde dehydrogenase 2, and Dectin-1

The gut CD103+ tolerogenic dendritic cells play a key role in maintaining immune balance by inducing oral tolerance, which has been implied in reducing autoimmunity. We recently reported that the oral administration of a fungal protein Lingzhi-8 (LZ-8) prevented autoimmune colitis in mice via maintaining barrier integrity. Here, we examined the functional effect of LZ-8 on gut CD103+ DCs and on autoimmune psoriasis in a mouse model. After orally administered LZ-8 to mice, the numbers of CD103+ DCs and their retinaldehyde dehydrogenase 2 (RALDH2) activities were increased in the mesenteric lymph nodes (mLNs), which were associated with increased regulatory T cell (Treg) in the spleen and LNs. This suggests that LZ-8 induces oral tolerance by enhancing the RALDH2 activity of CD103+ DCs. In addition, the imiquimod (IMQ)-induced psoriasis-like dermatitis was attenuated in mice after LZ-8 pretreatment. In the mechanistic study, we generated gut CD103+ DC-like cells from bone marrow (BM) of wild-type mouse and cultured them in the presence of retinoic acid (RA) in vitro. We found that LZ-8 directly enhanced the RALDH2 activity of these RA-primed CD103+ DCs, which was dependent on Dectin-1 and Syk signaling pathways but not TLR4. Together, our study demonstrated that LZ-8 facilitated gut tolerogenic CD103+ DC-mediated immunosuppression by enhancing RALDH2 activity, increasing Treg cell population, and signaling through Dectin-1 and Syk. Our findings provide a novel strategy for treating psoriasis and potentially other autoimmune diseases.

Organismal mucosal immunology: A perspective through the eyes of game theory

In complex organisms, functional units must interact cohesively to maintain homeostasis, especially within mucosal barriers that house diverse, specialized cell exposed to constant environmental challenges. Understanding how homeostasis at mucosal barriers is maintained and how its disruption can lead to autoimmune diseases or cancer, requires a holistic view. Although omics approaches and systems immunology have become powerful tools, they are not without limitations; interpretations may reflect researchers' assumptions, even if other explanations exist. In this perspective, I propose that applying game theory concepts to mucosal immunology could help interpret complex data, offering fresh perspectives and supporting the exploration of alternative scenarios. By framing the mucosal immune system as a network of strategic interactions with multiple possible outcomes, game theory, which analyzes strategic interactions and decision-making processes, could illuminate novel cell types and functions, cell interactions, and responses to pathogens and commensals, leading to a more comprehensive understanding of immune homeostasis and diseases. In addition, game theory might encourage researchers to consider a broader range of possibilities, reduce the risk of myopic thinking, and ultimately enable a more refined and comprehensive understanding of the complexity of the immune system at mucosal barriers. This perspective aims to introduce game theory as a complementary framework for mucosal immunologists, encouraging them to incorporate these concepts into data interpretation and system modeling.

How the early life microbiome shapes immune programming in childhood asthma and allergies

Despite advances in our understanding of their diagnosis and treatment, pediatric allergies impose substantial burdens on affected children, families, and healthcare systems. Further, the prevalence of allergic diseases has dramatically increased over the past half-century, leading to additional concerns and concerted efforts to identify the origins, potential predictors and preventions, and therapies of allergic diseases. Together with the increase in allergic diseases, changes in lifestyle and early-life environmental influences have corresponded with changes in colonization patterns of the infant gut microbiome. The gut microbiome plays a key role in developing the immune system, thus greatly influencing the development of allergic disease. In this review, we specifically highlight the importance of the proper maturation and composition of the gut microbiome as an essential step in healthy child development or disease progression. By exploring the intertwined development of the immune system and microbiome across pediatric allergic diseases, we provide insights into potential novel strategies for their prevention and management.

Protective effects of carnosic acid on growth performance, intestinal barrier, and cecal microbiota in yellow-feathered broilers under lipopolysaccharide challenge

This research was performed to investigate protective effects of carnosic acid on growth performance, intestinal barrier, and cecal microbiota of lipopolysaccharide-challenged broilers. Three hundred 1-day-old yellow-feathered broilers (male) were allocated randomly into 5 treatments, with 6 replicates per treatment, and 10 birds per replicate cage. Birds in both the control group (CON) and the lipopolysaccharide-challenged group were provided with a basal diet, while others were fed a basal diet supplemented with 20, 40, and 60 mg/kg carnosic acid (CA20, CA40, CA60), respectively. At 17, 19, and 21 days of age, birds were injected intraperitoneally with lipopolysaccharide (500 μg/kg body weight), except those in CON, which were injected with saline. Compared with challenged birds, the CA20, CA40, and CA60 increased (P < 0.05) the final body weight, average daily gain, and average daily feed intake, and the CA40 and CA60 also decreased diarrhea rate. Compared with challenged birds, carnosic acid reduced (P < 0.05) plasmal levels of D-lactic acid and endotoxin, increased (P < 0.05) the villus height to crypt depth ratio, and the number of goblet cells in duodenum. The CA40 and CA60 elevated (P < 0.05) relative expression of cell junction proteins (Claudin-1/-2 and ZO-1/-2/-3) and MUC-2 in duodenum, while decreased (P < 0.05) relative expression of TLR2, TLR4, and the concentrations of IL-6, IL-10, TNF-α, TGF-β1 in duodenum. CA40 also increased (P < 0.05) the α-diversity of the cecal microbiota and boosted (P < 0.05) the relative abundance of beneficial phyla and genera, particularly Firmicutes, Anaerofilum, and Papilibacter. In conclusion, dietary supplementation with carnosic acid showed protective effects on the growth performance and intestinal health in challenged broilers by down-regulating the expression of TLRs (TLR2/4) and inhibiting the production of inflammatory cytokines, strengthening the tight junction in intestinal epithelial cells, and enhancing the diversity of microbiota and the relative abundance of beneficial bacteria. When supplemented to diet of broilers, 40 mg/kg carnosic acid was recommended.

Uncovering the Beneficial Role of Limosilactobacillus fermentum E7 Exhibiting Antioxidant Activity in Ameliorating DSS-Induced Ulcerative Colitis in a Murine Model

BACKGROUND

Ulcerative colitis (UC) is a chronic intestinal disease of growing global concern. Bacteria associated with fermented food or probiotics regulate immune and inflammatory responses, playing a key role in intestinal immune homeostasis.

RESULTS

Five probiotics with relatively good antioxidant effects, namely Lactiplantibacillus plantarum H6, Latilactobacillus sakei QC9, Limosilactobacillus fermentum E7, Bacillus subtills D1, and Bacillus licheniformis Q13, were screened out from 30 strains of probiotics through in vitro antioxidant assays. The five probiotics had varying degrees of alleviating effects on UC mice and improved various physiological indicators, such as oxidative stress parameters and histopathological sections. The effects of E7, D1, and Q13 were more pronounced. Furthermore, E7 effectively regulated UC mouse intestinal microbiota composition, increased short-chain fatty acid concentration, and promoted the expression of anti-inflammatory factors, such as interleukin 10 (IL-10), while suppressing that of pro-inflammatory factors, such as interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α). Meanwhile, D1 and Q13 only exhibited partial alleviating effects. Finally, E7 increased the expression of tight junction proteins in colon tissues.

CONCLUSIONS

E7 showed superior efficacy to other probiotics in alleviating UC, offering novel therapeutic prospects for safer and effective management of UC.

A Comprehensive Review of Challenges in Oral Drug Delivery Systems and Recent Advancements in Innovative Design Strategies

The oral route of drug administration is often preferred by patients and healthcare providers due to its convenience, ease of use, non-invasiveness, and patient acceptance. However, traditional oral dosage forms have several limitations, including low bioavailability, limited drug loading capacity, and stability and storage issues, particularly with solutions and suspensions. Over the years, researchers have dedicated considerable effort to developing novel oral drug delivery systems to overcome these limitations. This review discusses various challenges associated with oral drug delivery systems, including biological, pharmaceutical, and physicochemical barriers. It also explores common delivery approaches, such as gastroretentive drug delivery, small intestine drug delivery, and colon-targeting drug delivery systems. Additionally, numerous strategies aimed at improving oral drug delivery efficiency are reviewed, including solid dispersion, absorption enhancers, lipidbased formulations, nanoparticles, polymer-based nanocarriers, liposomal formulations, microencapsulation, and micellar formulations. Furthermore, innovative approaches like orally disintegrating tablets (ODT), orally disintegrating films (ODF), layered tablets, micro particulates, self-nano emulsifying formulations (SNEF), and controlled release dosage forms are explored for their potential in enhancing oral drug delivery efficiency and promoting patients' compliance. Overall, this review highlights significant progress in addressing challenges in the pharmaceutical industry and clinical settings, offering novel approaches for the development of effective oral drug delivery systems.

The renaissance of oral tolerance: merging tradition and new insights

Oral tolerance is the process by which feeding of soluble proteins induces antigen-specific systemic immune unresponsiveness. Oral tolerance is thought to have a central role in suppressing immune responses to 'harmless' food antigens, and its failure can lead to development of pathologies such as food allergies or coeliac disease. However, on the basis of long-standing experimental observations, the relevance of oral tolerance in human health has achieved new prominence recently following the discovery that oral administration of peanut proteins prevents the development of peanut allergy in at-risk human infants. In this Review, we summarize the new mechanistic insights into three key processes necessary for the induction of tolerance to oral antigens: antigen uptake and transport across the small intestinal epithelial barrier to the underlying immune cells; the processing, transport and presentation of fed antigen by different populations of antigen-presenting cells; and the development of immunosuppressive T cell populations that mediate antigen-specific tolerance. In addition, we consider how related but distinct processes maintain tolerance to bacterial antigens in the large intestine. Finally, we outline the molecular mechanisms and functional consequences of failure of oral tolerance and how these may be modulated to enhance clinical outcomes and prevent disease.

Changes in the Phenotype and Metabolism of Peritoneal Macrophages in Mucin-2 Knockout Mice and Partial Restoration of Their Functions In Vitro After L-Fucose Treatment

In the development of inflammatory bowel disease (IBD), peritoneal macrophages contribute to the resident intestinal macrophage pool. Previous studies have demonstrated that oral administration of L-fucose exerts an immunomodulatory effect and repolarizes the peritoneal macrophages in vivo in mice. In this study, we analyzed the phenotype and metabolic profile of the peritoneal macrophages from Muc2-/- mice, as well as the effect of L-fucose on the metabolic and morphological characteristics of these macrophages in vitro. The investigation utilized flow cytometry, quantitative PCR (qPCR), measurement of the intracellular ATP and Ca2+ concentrations, an analysis of mitochondrial respiration and membrane potential, and transmission electron microscopy (TEM) for ultrastructural evaluations. The Muc2-/- mice exhibited lower intracellular ATP and Ca2+ levels in their peritoneal macrophages, a higher percentage of stellate macrophages, and an increased oxygen consumption rate (OCR), combined with a higher percentage of mitochondria displaying an abnormal ultrastructure. Additionally, there was a five-fold increase in condensed mitochondria compared to their level in C57BL/6 mice. The number of CD209+ peritoneal macrophages was reduced three-fold, while the number of M1-like cells increased two-fold in the Muc2-/- mice. L-fucose treatment enhanced ATP production and reduced the expression of the Parp1, Mt-Nd2, and Mt-Nd6 genes, which may suggest a reduction in pro-inflammatory factor production and a shift in the differentiation of peritoneal macrophages towards the M2 phenotype.

The Dectin-1 and Dectin-2 clusters: C-type lectin receptors with fundamental roles in immunity

The ability of myeloid cells to recognize and differentiate endogenous or exogenous ligands rely on the presence of different transmembrane protein receptors. C-type lectin receptors (CLRs), defined by the presence of a conserved structural motif called C-type lectin-like domain (CTLD), are a crucial family of receptors involved in this process, being able to recognize a diverse range of ligands from glycans to proteins or lipids and capable of initiating an immune response. The Dectin-1 and Dectin-2 clusters involve two groups of CLRs, with genes genomically linked within the natural killer cluster of genes in both humans and mice, and all characterized by the presence of a single extracellular CTLD. Fundamental immune cell functions such as antimicrobial effector mechanisms as well as internalization and presentation of antigens are induced and/or regulated through activatory, or inhibitory signalling pathways triggered by these receptors after ligand binding. In this review, we will discuss the most recent concepts regarding expression, ligands, signaling pathways and functions of each member of the Dectin clusters of CLRs, highlighting the importance and diversity of their functions.

Immunomodulatory and anti-inflammatory properties of immunoglobulin G antibodies

Antibodies provide an essential layer of protection from infection and reinfection with microbial pathogens. An impaired ability to produce antibodies results in immunodeficiency and necessitates the constant substitution with pooled serum antibodies from healthy donors. Among the five antibody isotypes in humans and mice, immunoglobulin G (IgG) antibodies are the most potent anti-microbial antibody isotype due to their long half-life, their ability to penetrate almost all tissues and due to their ability to trigger a wide variety of effector functions. Of note, individuals suffering from IgG deficiency frequently produce self-reactive antibodies, suggesting that a normal serum IgG level also may contribute to maintaining self-tolerance. Indeed, the substitution of immunodeficient patients with pooled serum IgG fractions from healthy donors, also referred to as intravenous immunoglobulin G (IVIg) therapy, not only protects the patient from infection but also diminishes autoantibody induced pathology, providing more direct evidence that IgG antibodies play an active role in maintaining tolerance during the steady state and during resolution of inflammation. The aim of this review is to discuss different conceptual models that may explain how serum IgG or IVIg can contribute to maintaining a balanced immune response. We will focus on pathways depending on the IgG fragment crystallizable (Fc) as pre-clinical data in various mouse model systems as well as human clinical data have demonstrated that the IgG Fc-domain recapitulates the ability of intact IVIg with respect to its ability to trigger resolution of inflammation. We will further discuss how the findings already have or are in the process of being translated to novel therapeutic approaches to substitute IVIg in treating autoimmune inflammation.

Wall of Resilience: How the Intestinal Epithelium Prevents Inflammatory Onslaught in the Gut

The intestinal epithelium forms the boundary between the intestinal immune system in the lamina propria and the outside world, the intestinal lumen, which contains a diverse array of microbial and environmental antigens. Composed of specialized cells, this epithelial monolayer has an exceptional turnover rate. Differentiated epithelial cells are released into the intestinal lumen within a few days, at the villus tip, a process that requires strict regulation. Dysfunction of the epithelial barrier increases the intestinal permeability and paves the way for luminal antigens to pass into the intestinal serosa. Stem cells at the bottom of Lieberkühn crypts provide a constant supply of mature epithelial cells. Differentiated intestinal epithelial cells exhibit a diverse array of mechanisms that enable communication with surrounding cells, fortification against microorganisms, and orchestration of nutrient absorption and hormonal balance. Furthermore, tight junctions regulate paracellular permeability properties, and their disruption can lead to an impairment of the intestinal barrier, allowing inflammation to develop or further progress. Intestinal epithelial cells provide a communication platform through which they maintain homeostasis with a spectrum of entities including immune cells, neuronal cells, and connective tissue cells. This homeostasis can be disrupted in disease, such as inflammatory bowel disease. Patients suffering from inflammatory bowel disease show an impaired gut barrier, dysregulated cellular communication, and aberrant proliferation and demise of cells. This review summarizes the individual cellular and molecular mechanisms pivotal for upholding the integrity of the intestinal epithelial barrier and shows how these can be disrupted in diseases, such as inflammatory bowel disease.

Dectin-1 as a therapeutic target for inflammatory bowel disease

Inflammatory bowel disease (IBD) encompasses chronic inflammatory conditions of the distal gastrointestinal tract, including Crohn's disease and ulcerative colitis. This chapter explores the potential of Dendritic cell-associated C-type lectin-1 (Dectin-1), a pattern recognition receptor, as a therapeutic target for IBD. We delve into the multifaceted roles of Dectin-1 in immune response modulation, focusing on its interactions with the gut microbiota and immune system. Key sections include an examination of intestinal dysbiosis and its impact on IBD, highlighting the critical role of fungal dysbiosis and immune responses mediated by Dectin-1. The chapter discusses the dual functions of Dectin-1 in maintaining gut homeostasis and its contribution to disease pathogenesis through interactions with the gut's fungal community. Furthermore, the genetic and molecular mechanisms underpinning Dectin-1's role in IBD susceptibility are explored, alongside its signaling pathways and their effects on immune modulation. We also present therapeutic strategies targeting Dectin-1, including innovative drug delivery systems that leverage its natural binding affinity for β-glucans, enhancing targeted delivery to inflamed tissues. The chapter underscores the potential of dietary modulation of Dectin-1 pathways to restore gut microbiota balance and suggests future research directions to fully exploit Dectin-1's therapeutic potential in managing IBD. By elucidating the complex interplay between Dectin-1 and the gut microbiota, this chapter provides insights into novel therapeutic approaches aimed at mitigating IBD symptoms and improving patient outcomes.

Activated sympathetic nerve post stroke downregulates Toll-like receptor 5 and disrupts the gut mucosal barrier

The gut permeability significantly increases after ischemic stroke, partly due to disrupted mucosal barrier, but the mechanism remains elusive. Here, we found that the mucus disruption starts at 2 h post stroke, whereas goblet cell functions remain intact. Meanwhile, the flagellated bacteria Helicobacter thrives and penetrates in the mucus layer. Elimination of the mucosal microbiota or transplantation of Helicobacter in germ-free mice reveals an important role of the mucosal microbiota in mucus disruption. The bacterial invasion is due to downregulated Toll-like receptor 5 (TLR5) and its downstream products flagellin-specific IgA and antimicrobial peptides. Knockdown of intestinal TLR5 increases the abundance of flagellated bacteria and exacerbates mucus injury. Intestinal TLR5 is downregulated by the activation of sympathetic nerve. Serum noradrenaline level is positively associated with flagellin level in patients with stroke and patients' prognosis. These findings reveal a neural pathway in which the sympathetic nerve disrupts the mucosal barrier, providing potential therapeutic targets for stroke injury.

Teleost Muc2 and Muc5ac: Key guardians of mucosal immunity in flounder (Paralichthys olivaceus)

Mucins secreted by mucous cells constitute a core part of the defense line against the invasion of pathogens. However, mucins' structure and immunological functions remain largely unknown in teleost fish. In this study, two typical mucins, Muc2 and Muc5ac of flounder (Paralichthys olivaceus), were cloned and their physicochemical properties, structure and conservation were analyzed. Notably, specific antibodies against flounder Muc2 and Muc5ac were developed. It was verified at the gene and protein level that Muc2 was expressed in the hindgut and gills but not in the skin, while Muc5ac was expressed in the skin and gills but not in the hindgut. After flounders were immunized by immersion with inactivated Edwardsiella tarda, Muc2 and Muc5ac were significantly upregulated at both the gene expression and protein levels, and Muc2+/Muc5ac+ mucous cells proliferated and increased secretion of Muc2 and Muc5ac. Moreover, Muc2 and Muc5ac exerted retention and clearance effects on E. tarda in a short period (within 1 dpi). These results revealed the characterization of fish mucins Muc2 and Muc5ac at the protein level and clarified the role of mucins as key guardians to maintain the mucus barrier, which advanced our understanding of teleost mucosal barrier.

Inulin-gel-based oral immunotherapy remodels the small intestinal microbiome and suppresses food allergy

Despite the potential of oral immunotherapy against food allergy, adverse reactions and loss of desensitization hinder its clinical uptake. Dysbiosis of the gut microbiota is implicated in the increasing prevalence of food allergy, which will need to be regulated to enable for an effective oral immunotherapy against food allergy. Here we report an inulin gel formulated with an allergen that normalizes the dysregulated ileal microbiota and metabolites in allergic mice, establishes allergen-specific oral tolerance and achieves robust oral immunotherapy efficacy with sustained unresponsiveness in food allergy models. These positive outcomes are associated with enhanced allergen uptake by antigen-sampling dendritic cells in the small intestine, suppressed pathogenic type 2 immune responses, increased interferon-γ+ and interleukin-10+ regulatory T cell populations, and restored ileal abundances of Eggerthellaceae and Enterorhabdus in allergic mice. Overall, our findings underscore the therapeutic potential of the engineered allergen gel as a suitable microbiome-modulating platform for food allergy and other allergic diseases.

Human milk oligosaccharides in preventing food allergy: A review through gut microbiota and immune regulation

Food allergy (FA) has increasingly attracted global attention in past decades. However, the mechanism and effect of FA are complex and varied, rendering it hard to prevention and management. Most of the allergens identified so far are macromolecular proteins in food and may have potential cross-reactions. Human milk oligosaccharides (HMOs) have been regarded as an ideal nutrient component for infants, as they can enhance the immunomodulatory capacity to inhibit the progress of FA. HMOs may intervene in the development of allergies by modifying gut microbiota and increasing specific short-chain fatty acids levels. Additionally, HMOs could improve the intestinal permeability and directly or indirectly regulate the balance of T helper cells and regulatory T cells by enhancing the inflammatory signaling pathways to combat FA. This review will discuss the influence factors of FA, key species of gut microbiota involved in FA, types of FA, and profiles of HMOs and provide evidence for future research trends to advance HMOs as potential therapeutic aids in preventing the progress of FA.

"Enhancing Oral Drug Absorption: Overcoming Physiological and Pharmaceutical Barriers for Improved Bioavailability"

The oral route stands out as the most commonly used method for drug administration, prized for its non-invasive nature, patient compliance, and easy administration. Several elements influence the absorption of oral medications, including their solubility, permeability across mucosal membranes, and stability within the gastrointestinal (GI) environment. Research has delved into comprehending physicochemical, biochemical, metabolic, and biological obstacles that impact the bioavailability of a drug. To improve oral drug absorption, several pharmaceutical technologies and delivery methods have been studied, including cyclodextrins, micelles, nanocarriers, and lipid-based carriers. This review examines both traditional and innovative drug delivery methods, as well as the physiological and pharmacological barriers influencing medication bioavailability when taken orally. Additionally, it describes the challenges and advancements in developing formulations suitable for oral use.

Cassia alata's dual role in modulating MUC2 expression in Eimeria papillata-infected jejunum and assessing its anti-inflammatory effects

Coccidiosis poses significant hazards to animals, particularly in terms of compromised health, reduced productivity, and economic losses in livestock farming. The conventional treatments for coccidiosis often involve synthetic drugs, contributing to concerns about drug resistance and environmental impact. The pressing need for eco-friendly alternatives is highlighted in this study, emphasizing the importance of exploring medicinal plants like Cassia alata leaf extracts (CAE) against Eimeria papillata-induced infection in mice. The CAE exhibited significant phenolic (2.17 ± 0.03 g/100 g) and flavonoid (0.14 ± 0.01 g/100 g) content and demonstrated notable antioxidant activity. In infected mice, the CAE treatment led to a substantial reduction in oocyst output (~6 fold), ameliorating necrotic enteritis and inflammatory changes in the jejunum. Additionally, CAE treatment increased goblet cell numbers (9.3 ± 0.1 / villus) and decreased macrophage infiltration in the intestinal villi. Molecular analyses revealed CAE's positive modulation of MUC2 gene and notably reduced the levels of pro-inflammatory cytokines (specifically IL-1β, IL-10, and IFN-γ) when contrasted with the infected cohort. Furthermore, CAE treatment significantly reduced nitric oxide levels (44.03 ± 2.4 μmol/mg), showcasing its anti-inflammatory properties. The findings of this study not only contribute to the understanding of CAE's therapeutic potential but also underscore the importance of seeking eco-friendly alternatives in the face of coccidiosis challenges, addressing both the well-being of animals and the sustainability of agricultural practices. RESEARCH HIGHLIGHTS: Cassia alata extract (CAE) exhibited significant phenolic and flavonoid content, displaying notable antioxidant activity. In infected mice, CAE treatment led to a substantial reduction in oocyst output, ameliorating necrotic enteritis and inflammatory changes in the jejunum. CAE treatment increased goblet cell numbers and decreased macrophage infiltration in the intestinal villi, while molecular analyses revealed its positive modulation of the MUC2 gene and notable reduction in pro-inflammatory cytokine levels. Additionally, CAE treatment significantly reduced nitric oxide levels, showcasing its anti-inflammatory properties.

Enterococcal-host interactions in the gastrointestinal tract and beyond

The gastrointestinal tract (GIT) is typically considered the natural niche of enterococci. However, these bacteria also inhabit extraintestinal tissues, where they can disrupt organ physiology and cause life-threatening infections. Here, we discuss how enterococci, primarily Enterococcus faecalis, interact with the intestine and other host anatomical locations such as the oral cavity, heart, liver, kidney, and vaginal tract. The metabolic flexibility of these bacteria allows them to quickly adapt to new environments, promoting their persistence in diverse tissues. In transitioning from commensals to pathogens, enterococci must overcome harsh conditions such as nutrient competition, exposure to antimicrobials, and immune pressure. Therefore, enterococci have evolved multiple mechanisms to adhere, colonize, persist, and endure these challenges in the host. This review provides a comprehensive overview of how enterococci interact with diverse host cells and tissues across multiple organ systems, highlighting the key molecular pathways that mediate enterococcal adaptation, persistence, and pathogenic behavior.

Lactobacillus gasseri ATCC33323 affects the intestinal mucosal barrier to ameliorate DSS-induced colitis through the NR1I3-mediated regulation of E-cadherin

Inflammatory bowel disease (IBD) is an immune system disorder primarily characterized by colitis, the exact etiology of which remains unclear. Traditional treatment approaches currently yield limited efficacy and are associated with significant side effects. Extensive research has indicated the potent therapeutic effects of probiotics, particularly Lactobacillus strains, in managing colitis. However, the mechanisms through which Lactobacillus strains ameliorate colitis require further exploration. In our study, we selected Lactobacillus gasseri ATCC33323 from the intestinal microbiota to elucidate the specific mechanisms involved in modulation of colitis. Experimental findings in a DSS-induced colitis mouse model revealed that L. gasseri ATCC33323 significantly improved physiological damage in colitic mice, reduced the severity of colonic inflammation, decreased the production of inflammatory factors, and preserved the integrity of the intestinal epithelial structure and function. It also maintained the expression and localization of adhesive proteins while improving intestinal barrier permeability and restoring dysbiosis in the gut microbiota. E-cadherin, a critical adhesive protein, plays a pivotal role in this protective mechanism. Knocking down E-cadherin expression within the mouse intestinal tract significantly attenuated the ability of L. gasseri ATCC33323 to regulate colitis, thus confirming its protective role through E-cadherin. Finally, transcriptional analysis and in vitro experiments revealed that L. gasseri ATCC33323 regulates CDH1 transcription by affecting NR1I3, thereby promoting E-cadherin expression. These findings contribute to a better understanding of the specific mechanisms by which Lactobacillus strains alleviate colitis, offering new insights for the potential use of L. gasseri as an alternative therapy for IBD, particularly in dietary supplementation.

The right educational environment: Oral tolerance in early life

Oral tolerance promotes the suppression of immune responses to innocuous antigen and is primarily mediated by regulatory T cell (Tregs). The development of oral tolerance begins in early life during a "window of tolerance," which occurs around weaning and is mediated by components in breastmilk. Herein, we review the factors dictating this window and how Tregs are uniquely educated in early life. In early life, the translocation of luminal antigen for Treg induction is primarily dictated by goblet cell-associated antigen passages (GAPs). GAPs in the colon are negatively regulated by maternally-derived epidermal growth factor and the microbiota, restricting GAP formation to the "periweaning" period (postnatal day 11-21 in mice, 4-6 months in humans). The induction of solid food also promotes the diversification of the bacteria such that bacterially-derived metabolites known to promote Tregs-short-chain fatty acids, tryptophan metabolites, and bile acids-peak during the periweaning phase. Further, breastmilk immunoglobulins-IgA and IgG-regulate both microbial diversity and the interaction of microbes with the epithelium, further controlling which antigens are presented to T cells. Overall, these elements work in conjunction to induce a long-lived population of Tregs, around weaning, that are crucial for maintaining homeostasis in adults.

The evolutionarily ancient FOXA transcription factors shape the murine gut microbiome via control of epithelial glycosylation

Evolutionary adaptation of multicellular organisms to a closed gut created an internal microbiome differing from that of the environment. Although the composition of the gut microbiome is impacted by diet and disease state, we hypothesized that vertebrates promote colonization by commensal bacteria through shaping of the apical surface of the intestinal epithelium. Here, we determine that the evolutionarily ancient FOXA transcription factors control the composition of the gut microbiome by establishing favorable glycosylation on the colonic epithelial surface. FOXA proteins bind to regulatory elements of a network of glycosylation enzymes, which become deregulated when Foxa1 and Foxa2 are deleted from the intestinal epithelium. As a direct consequence, microbial composition shifts dramatically, and spontaneous inflammatory bowel disease ensues. Microbiome dysbiosis was quickly reversed upon fecal transplant into wild-type mice, establishing a dominant role for the host epithelium, in part mediated by FOXA factors, in controlling symbiosis in the vertebrate holobiont.

The Potential Role of Plant Polysaccharides in Treatment of Ulcerative Colitis

Ulcerative colitis (UC) results in inflammation and ulceration of the colon and the rectum's inner lining. The application of herbal therapy in UC is increasing worldwide. As natural macromolecular compounds, polysaccharides have a significant role in the treatment of UC due to advantages of better biodegradation, good biocompatibility, immunomodulatory activity, and low reactogenicity. Therefore, polysaccharide drug formulation is becoming a potential candidate for UC treatment. In this review, we summarize the etiology and pathogenesis of UC and the therapeutic effects of polysaccharides on UC, such as regulating the expression of cytokines and tight junction proteins and modulating the balance of immune cells and intestinal microbiota. Polysaccharides can also serve as drug delivery carriers to enhance drug targeting and reduce side effects. This review provides a theoretical basis for applying natural plant polysaccharides in the prevention and treatment of UC.

Materials Strategies to Overcome the Foreign Body Response

The foreign body response (FBR) is an immune-mediated reaction that can occur with most biomaterials and biomedical devices. The FBR initiates a deterioration in the performance of implantable devices, representing a longstanding challenge that consistently hampers their optimal utilization. Over the last decade, significant strides are achieved based on either hydrogel design or surface modifications to mitigate the FBR. This review delves into recent material strategies aimed at mitigating the FBR. Further, the authors look forward to future novel anti-FBR materials from the perspective of clinical translation needs. Such prospective materials hold the potential to attenuate local immune responses, thereby significantly enhancing the overall performance of implantable devices.

Allergen-specific IgA and IgG antibodies as inhibitors of mast cell function in food allergy

Food allergy, a group of adverse immune responses to normally innocuous food protein antigens, is an increasingly prevalent public health issue. The most common form is IgE-mediated food allergy in which food antigen-induced crosslinking of the high-affinity IgE-receptor, FcεRI, on the surface of mast cells triggers the release of inflammatory mediators that contribute to a wide range of clinical manifestations, including systemic anaphylaxis. Mast cells also play a critical function in adaptive immunity to foods, acting as adjuvants for food-antigen driven Th2 cell responses. While the diagnosis and treatment of food allergy has improved in recent years, no curative treatments are currently available. However, there is emerging evidence to suggest that both allergen-specific IgA and IgG antibodies can counter the activating effects of IgE antibodies on mast cells. Most notably, both antigen-specific IgA and IgG antibodies are induced in the course of oral immunotherapy. In this review, we highlight the role of mast cells in food allergy, both as inducers of immediate hypersensitivity reactions and as adjuvants for type 2 adaptive immune responses. Furthermore, we summarize current understanding of the immunomodulatory effects of antigen-specific IgA and IgG antibodies on IgE-induced mast cell activation and effector function. A more comprehensive understanding of the regulatory role of IgA and IgG in food allergy may provide insights into physiologic regulation of immune responses to ingested antigens and could seed novel strategies to treat allergic disease.

Molecular Mechanisms of Intestinal Protection by Levilactobacillus brevis 23017 against Salmonella typhimurium C7731-Induced Damage: Role of Nrf2

The treatment and prevention of pathogenic diseases by lactic acid bacteria (LAB) has attracted more and more attention. As a special LAB, Levilactobacillus brevis (L. brevis) has relatively less research on its antibacterial infection in vivo, and its protective effect and mechanism still need to be fully studied. In this study, we selected L. brevis 23017, which can regulate the intestinal immunity of the host animal and resist pathogen infection, to evaluate its protective role and potential molecular mechanisms in the mouse model of S. typhimurium C7731 infection. As expected, we confirmed that L. brevis 23017 reduced the diarrhea rate and increased the daily weight gain and survival rate of the mouse model, and inhibited S. typhimurium colonization in the jejunum and liver. It also reduced the level of oxidative damage and protected the integrity of intestinal tissue by increasing the activity of intestinal antioxidant enzymes (SOD, GSH-Px and T-AOC). From the perspective of intestinal mucosal barrier injury and repair, it was confirmed that L. brevis 23017 could increase the expression levels of intestinal tight junction proteins (ZO-1 and OCLN). Our research results also show that L. brevis 23017 inhibits the inflammatory response and promotes the occurrence of cellular immunity in the body by promoting the increase in IL-10 and inhibiting IL-13 in serum and intestinal tissue. Notably, L. brevis 23017 increased total secretory immunoglobulin A (SIgA) levels in the intestine, which were closely associated with elevated levels of IL-5, IL-13, pIgR, j-chain, and IgAα-chain. In addition, L. brevis 23017 increased the expression of antioxidant proteins Nrf2, NQO1, and HO-1 associated with Nrf2 signaling to inhibit intestinal oxidative damage. This mechanism may be responsible for its protective effect against S. typhimurium-infected intestine. Our study provides new evidence and theoretical support for the analysis of the anti-bacterial infection effect and mechanism of L. brevis, which will contribute to the development of L. brevis and the treatment of pathogenic bacteria intestinal infection.

Recent progress on engineered micro/nanomaterials mediated modulation of gut microbiota for treating inflammatory bowel disease

Inflammatory bowel disease (IBD) is a type of chronic recurrent inflammation disease that mainly includes Crohn's disease and ulcerative colitis. Currently, the treatments for IBD remain highly challenging, with clinical treatment drugs showing limited efficacy and adverse side effects. Thus, developing drug candidates with comprehensive therapeutic effects, high efficiency, and low toxicity is urgently needed. Recently, micro/nanomaterials have attracted considerable interest because of their bioavailability, multitarget and efficient effects on IBD. In addition, gut modulation plays a substantial role in restoring intestinal homeostasis. Therefore, efficient microbiota-based strategies modulating gut microenvironment have great potential in remarkably treating IBD. With the development of micro- and nanomaterials for the treatment of IBD and more in-depth studies of their therapeutic mechanisms, it has been found that these treatments also have a tendency to positively regulate the intestinal flora, resulting in an increase in the beneficial flora and a decrease in the level of pathogenic bacteria, thus regulating the composition of the intestinal flora to a normal state. In this review, we first present the interactions among the immune system, intestinal barrier, and gut microbiome. In addition, recent advances in administration routes and methods that positively arouse the regulation of intestinal flora for IBD using probiotics, prebiotics, and redox-active micro/nanomaterials have been reviewed. Finally, the key challenges and critical perspectives of gut microbiota-based micro/nanomaterial treatment are also discussed.

Lycium barbarum polysaccharide remodels colon inflammatory microenvironment and improves gut health

Aim

Disturbed intestinal microbiota has been implicated in the inflammatory microenvironment of the colon, which usually results in ulcerative colitis (UC). Given the limitations of these drugs, it is important to explore alternative means of protecting the gut health from UC. This study aimed to investigate the potential of polysaccharides as beneficial nutrients in the regulation of the gut microbiota, which determines the inflammatory microenvironment of the colon.

Materials and methods

Mice were treated with dextran sulfate sodium (DSS) to evaluate the effects and mechanisms of Lycium barbarum polysaccharide (LBP) in remodeling the inflammatory microenvironment and improving gut health. Body weight and disease activity indices were monitored daily. Hematoxylin and eosin staining was used to analyze colon dynamics. The levels of inflammatory indicators and expression of MUC-2, claudin-1, ZO-1, and G-protein-coupled receptor 5 (TGR5) were determined using assay kits and immunohistochemistry, respectively. 16S rRNA high-throughput sequencing of the intestinal microbiota and liquid chromatography-tandem mass spectrometry for related bile acids were used.

Results

LBP significantly improved the colonic tissue structure by upregulating MUC-2, claudin-1, and ZO-1 protein expression. The bacterial genus Dubosiella was dominant in healthy mice, but significantly decreased in mice treated with DSS. LBP rehabilitated Dubosiella in the sick guts of DSS mice to a level close to that of healthy mice. The levels of other beneficial bacterial genera Akkermansia and Bifidobacterium were also increased, whereas those of the harmful bacterial genera Turicibacter, Clostridium_sensu_stricto_1, Escherichia-Shigella, and Faecalibaculum decreased. The activity of beneficial bacteria promoted the bile acids lithocholic and deoxycholic acids in mice with UC, which improved the gut barrier function through the upregulation of TGR5.

Conclusion

The inflammatory microenvironment in the gut is determined by the balance of the gut microbiota. LBP showed great potential as a beneficial nutrient for rehabilitating Dubosiella which is dominant in the gut of healthy mice. Nutrient-related LBP may play an important role in gut health management.

Roles of airway and intestinal epithelia in responding to pathogens and maintaining tissue homeostasis

Epithelial cells form a resilient barrier and orchestrate defensive and reparative mechanisms to maintain tissue stability. This review focuses on gut and airway epithelia, which are positioned where the body interfaces with the outside world. We review the many signaling pathways and mechanisms by which epithelial cells at the interface respond to invading pathogens to mount an innate immune response and initiate adaptive immunity and communicate with other cells, including resident microbiota, to heal damaged tissue and maintain homeostasis. We compare and contrast how airway and gut epithelial cells detect pathogens, release antimicrobial effectors, collaborate with macrophages, Tregs and epithelial stem cells to mount an immune response and orchestrate tissue repair. We also describe advanced research models for studying epithelial communication and behaviors during inflammation, tissue injury and disease.

β-Catenin in Dendritic Cells Negatively Regulates CD8 T Cell Immune Responses through the Immune Checkpoint Molecule Tim-3

Recent studies have demonstrated that β-catenin in dendritic cells (DCs) serves as a key mediator in promoting both CD4 and CD8 T cell tolerance, although the mechanisms underlying how β-catenin exerts its functions remain incompletely understood. Here, we report that activation of β-catenin leads to the up-regulation of inhibitory molecule T-cell immunoglobulin and mucin domain 3 (Tim-3) in type 1 conventional DCs (cDC1s). Using a cDC1-targeted vaccine model with anti-DEC-205 engineered to express the melanoma antigen human gp100 (anti-DEC-205-hgp100), we demonstrated that CD11c-β-cateninactive mice exhibited impaired cross-priming and memory responses of gp100-specific CD8 T (Pmel-1) cells upon immunization with anti-DEC-205-hgp100. Single-cell RNA sequencing (scRNA-seq) analysis revealed that β-catenin in DCs negatively regulated transcription programs for effector function and proliferation of primed Pmel-1 cells, correlating with suppressed CD8 T cell immunity in CD11c-β-cateninactive mice. Further experiments showed that treating CD11c-β-cateninactive mice with an anti-Tim-3 antibody upon anti-DEC-205-hgp100 vaccination led to restored cross-priming and memory responses of gp100-specific CD8 T cells, suggesting that anti-Tim-3 treatment likely synergizes with DC vaccines to improve their efficacy. Indeed, treating B16F10-bearing mice with DC vaccines using anti-DEC-205-hgp100 in combination with anti-Tim-3 treatment resulted in significantly reduced tumor growth compared with treatment with the DC vaccine alone. Taken together, we identified the β-catenin/Tim-3 axis as a potentially novel mechanism to inhibit anti-tumor CD8 T cell immunity and that combination immunotherapy of a DC-targeted vaccine with anti-Tim-3 treatment leads to improved anti-tumor efficacy.

Gut microbiota and acute kidney injury: immunological crosstalk link

The gut microbiota, often called the "forgotten organ," plays a crucial role in bidirectional communication with the host for optimal physiological function. This communication helps regulate the host's immunity and metabolism positively and negatively. Many factors influence microbiota homeostasis and subsequently lead to an immune system imbalance. The correlation between an unbalanced immune system and acute diseases such as acute kidney injury is not fully understood, and the role of gut microbiota in disease pathogenesis is still yet uncovered. This review summarizes our understanding of gut microbiota, focusing on the interactions between the host's immune system and the microbiome and their impact on acute kidney injury.

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.

Endotoxin Inflammatory Action on Cells by Dysregulated-Immunological-Barrier-Linked ROS-Apoptosis Mechanisms in Gut-Liver Axis

Our study highlighted the immune changes by pro-inflammatory biomarkers in the gut-liver-axis-linked ROS-cell death mechanisms in chronic and acute inflammations when gut cells are exposed to endotoxins in patients with hepatic cirrhosis or steatosis. In duodenal tissue samples, gut immune barrier dysfunction was analyzed by pro-inflammatory biomarker expressions, oxidative stress, and cell death by flow cytometry methods. A significant innate and adaptative immune system reaction was observed as result of persistent endotoxin action in gut cells in chronic inflammation tissue samples recovered from hepatic cirrhosis with the A-B child stage. Instead, in patients with C child stage of HC, the endotoxin tolerance was installed in cells, characterized by T lymphocyte silent activation and increased Th1 cytokines expression. Interesting mechanisms of ROS-cell death were observed in chronic and acute inflammation samples when gut cells were exposed to endotoxins and immune changes in the gut-liver axis. Late apoptosis represents the chronic response to injury induction by the gut immune barrier dysfunction, oxidative stress, and liver-dysregulated barrier. Meanwhile, necrosis represents an acute and severe reply to endotoxin action on gut cells when the immune system reacts to pro-inflammatory Th1 and Th2 cytokines releasing, offering protection against PAMPs/DAMPs by monocytes and T lymphocyte activation. Flow cytometric analysis of pro-inflammatory biomarkers linked to oxidative stress-cell death mechanisms shown in our study recommends laboratory techniques in diagnostic fields.

Symbiotic Synergy from Sponges to Humans: Microflora-Host Harmony Is Crucial for Ensuring Survival and Shielding against Invading Pathogens

Gut microbiota plays several roles in the host organism's metabolism and physiology. This phenomenon holds across different species from different kingdoms and classes. Different species across various classes engage in continuous crosstalk via various mechanisms with their gut microbiota, ensuring homeostasis of the host. In this Review, the diversity of the microflora, the development of the microflora in the host, its regulations by the host, and its functional implications on the host, especially in the context of dysbiosis, are discussed across different organisms from sponges to humans. Overall, our review aims to address the indispensable nature of the microbiome in the host's survival, fitness, and protection against invading pathogens.

Brain-Gut-Microbiota Axis in Amyotrophic Lateral Sclerosis: A Historical Overview and Future Directions

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease which is strongly associated with age. The incidence of ALS increases from the age of 40 and peaks between the ages of 65 and 70. Most patients die of respiratory muscle paralysis or lung infections within three to five years of the appearance of symptoms, dealing a huge blow to patients and their families. With aging populations, improved diagnostic methods and changes in reporting criteria, the incidence of ALS is likely to show an upward trend in the coming decades. Despite extensive researches have been done, the cause and pathogenesis of ALS remains unclear. In recent decades, large quantities of studies focusing on gut microbiota have shown that gut microbiota and its metabolites seem to change the evolvement of ALS through the brain-gut-microbiota axis, and in turn, the progression of ALS will exacerbate the imbalance of gut microbiota, thereby forming a vicious cycle. This suggests that further exploration and identification of the function of gut microbiota in ALS may be crucial to break the bottleneck in the diagnosis and treatment of this disease. Hence, the current review summarizes and discusses the latest research advancement and future directions of ALS and brain-gut-microbiota axis, so as to help relevant researchers gain correlative information instantly.

Immunity to Cryptosporidium: insights into principles of enteric responses to infection

Cryptosporidium parasites replicate within intestinal epithelial cells and are an important cause of diarrhoeal disease in young children and in patients with primary and acquired defects in T cell function. This Review of immune-mediated control of Cryptosporidium highlights advances in understanding how intestinal epithelial cells detect this infection, the induction of innate resistance and the processes required for activation of T cell responses that promote parasite control. The development of a genetic tool set to modify Cryptosporidium combined with tractable mouse models provide new opportunities to understand the principles that govern the interface between intestinal epithelial cells and the immune system that mediate resistance to enteric pathogens.

Engineering Strategies to Modulate the Gut Microbiome and Immune System

The gut microbiota, predominantly residing in the colon, is a complex ecosystem with a pivotal role in the host immune system. Dysbiosis of the gut microbiota has been associated with various diseases, and there is an urgent need to develop new therapeutics that target the microbiome and restore immune functions. This Brief Review discusses emerging therapeutic strategies that focus on oral delivery systems for modulating the gut microbiome. These strategies include genetic engineering of probiotics, probiotic-biomaterial hybrids, dietary fibers, and oral delivery systems for microbial metabolites, antimicrobial peptides, RNA, and antibiotics. Engineered oral formulations have demonstrated promising outcomes in reshaping the gut microbiome and influencing immune responses in preclinical studies. By leveraging these approaches, the interplay between the gut microbiota and the immune system can be harnessed for the development of novel therapeutics against cancer, autoimmune disorders, and allergies.

Small Intestinal Goblet Cells Control Humoral Immune Responses and Mobilization During Enteric Infection

Humoral immune responses within the gut play diverse roles including pathogen clearance during enteric infections, maintaining tolerance, and facilitating the assemblage and stability of the gut microbiota. How these humoral immune responses are initiated and contribute to these processes are well studied. However, the signals promoting the expansion of these responses and their rapid mobilization to the gut mucosa are less well understood. Intestinal goblet cells form goblet cell-associated antigen passages (GAPs) to deliver luminal antigens to the underlying immune system and facilitate tolerance. GAPs are rapidly inhibited during enteric infection to prevent inflammatory responses to innocuous luminal antigens. Here we interrogate GAP inhibition as a key physiological response required for effective humoral immunity. Independent of infection, GAP inhibition resulted in enrichment of transcripts representing B cell recruitment, expansion, and differentiation into plasma cells in the small intestine (SI), which were confirmed by flow cytometry and ELISpot assays. Further we observed an expansion of isolated lymphoid follicles within the SI, as well as expansion of plasma cells in the bone marrow upon GAP inhibition. S1PR1-induced blockade of leukocyte trafficking during GAP inhibition resulted in a blunting of SI plasma cell expansion, suggesting that mobilization of plasma cells from the bone marrow contributes to their expansion in the gut. However, luminal IgA secretion was only observed in the presence of S. typhimurium infection, suggesting that although GAP inhibition mobilizes a mucosal humoral immune response, a second signal is required for full effector function. Overriding GAP inhibition during enteric infection abrogated the expansion of laminar propria IgA+ plasma cells. We conclude that GAP inhibition is a required physiological response for efficiently mobilizing mucosal humoral immunity in response to enteric infection.

Oral Administration of Cancer Vaccines: Challenges and Future Perspectives

Cancer vaccines, a burgeoning strategy in cancer treatment, are exploring innovative administration routes to enhance patient and medical staff experiences, as well as immunological outcomes. Among these, oral administration has surfaced as a particularly noteworthy approach, which is attributed to its capacity to ignite both humoral and cellular immune responses at systemic and mucosal tiers, thereby potentially bolstering vaccine efficacy comprehensively and durably. Notwithstanding this, the deployment of vaccines through the oral route in a clinical context is impeded by multifaceted challenges, predominantly stemming from the intricacy of orchestrating effective oral immunogenicity and necessitating strategic navigation through gastrointestinal barriers. Based on the immunogenicity of the gastrointestinal tract, this review critically analyses the challenges and recent advances and provides insights into the future development of oral cancer vaccines.

Pregnancy Protects against Abnormal Gut Permeability Promoted via the Consumption of a High-Fat Diet in Mice

The consumption of large amounts of dietary fats and pregnancy are independent factors that can promote changes in gut permeability and the gut microbiome landscape. However, there is limited evidence regarding the impact of pregnancy on the regulation of such parameters in females fed a high-fat diet. Here, gut permeability and microbiome landscape were evaluated in a mouse model of diet-induced obesity in pregnancy. The results show that pregnancy protected against the harmful effects of the consumption of a high-fat diet as a disruptor of gut permeability; thus, there was a two-fold reduction in FITC-dextran passage to the bloodstream compared to non-pregnant mice fed a high-fat diet (p < 0.01). This was accompanied by an increased expression of gut barrier-related transcripts, particularly in the ileum. In addition, the beneficial effect of pregnancy on female mice fed the high-fat diet was accompanied by a reduced presence of bacteria belonging to the genus Clostridia, and by increased Lactobacillus murinus in the gut (p < 0.05). Thus, this study advances the understanding of how pregnancy can act during a short window of time, protecting against the harmful effects of the consumption of a high-fat diet by promoting an increased expression of transcripts encoding proteins involved in the regulation of gut permeability, particularly in the ileum, and promoting changes in the gut microbiome.

Integrated Analysis of the Intestinal Microbiota and Transcriptome of Fenneropenaeus chinensis Response to Low-Salinity Stress

Salinity is an important environmental stress factor in mariculture. Shrimp intestines harbor dense and diverse microbial communities that maintain host health and anti-pathogen capabilities under salinity stress. In this study, 16s amplicon and transcriptome sequencing were used to analyze the intestine of Fenneropenaeus chinensis under low-salinity stress (15 ppt). This study aimed to investigate the response mechanisms of the intestinal microbiota and gene expression to acute low-salinity stress. The intestinal tissues of F. chinensis were analyzed using 16S microbiota and transcriptome sequencing. The microbiota analysis demonstrated that the relative abundances of Photobacterium and Vibrio decreased significantly, whereas Shewanella, Pseudomonas, Lactobacillus, Ralstonia, Colwellia, Cohaesibacter, Fusibacter, and Lachnospiraceae_NK4A136_group became the predominant communities. Transcriptome sequencing identified numerous differentially expressed genes (DEGs). The DEGs were clustered into many Gene Ontology terms and further enriched in some immunity- or metabolism-related Kyoto Encyclopedia of Genes and Genomes pathways, including various types of N-glycan biosynthesis, amino acid sugar and nucleotide sugar metabolism, and lysosome and fatty acid metabolism. Correlation analysis between microbiota and DEGs showed that changes in Pseudomonas, Ralstonia, Colwellia, and Cohaesibacter were positively correlated with immune-related genes such as peritrophin-1-like and mucin-2-like, and negatively correlated with caspase-1-like genes. Low-salinity stress caused changes in intestinal microorganisms and their gene expression, with a close correlation between them.

The use of benzalkonium chloride in topical glaucoma treatment: An investigation of the efficacy and safety of benzalkonium chloride-preserved intraocular pressure-lowering eye drops and their effect on conjunctival goblet cells

ENGLISH SUMMARY

Glaucoma is a leading cause of the global prevalence of irreversible blindness. The pathogenesis of glaucoma is not entirely known, but the major risk factors include advancing age, genetic predisposition, and increased intraocular pressure (IOP). The only evidence-based treatment is a lowering of IOP through the use of eye drops, laser procedures, or surgical interventions. Although laser treatment is gaining recognition as a first-choice treatment option, the most common approach for managing glaucoma is IOP-lowering eye drops. A major challenge in the treatment is the occurrence of adverse events and poor adherence. In this context, the ocular surface is an area of great concern, as most glaucoma patients have dry eye disease (DED), which is largely caused by eye drops. Preservation with benzalkonium chloride (BAK) is a controversial topic due to its potential role as a significant cause of DED. A systematic review and meta-analyses investigate potential differences in efficacy and safety between BAK-preserved and BAK-free anti-glaucomatous eye drops (I). Many of the included studies report on ocular surface damage caused by the application of BAK-preserved eye drops. However, the meta-analyses addressing hyperemia, number of ocular adverse events, and tear break-up time did not identify any significant differences. The latter is likely due to varying measurement methods, different endpoints, and study durations. It is, therefore, possible that the large variations between the studies conceal differences in the safety profiles. The efficacy meta-analysis finds that there are no differences in the IOP-lowering effect between BAK-preserved and BAK-free eye drops, indicating that BAK is not necessary for the effectiveness of eye drops. To promote more homogeneous choices of endpoints and methods when evaluating BAK-preserved and BAK-free glaucoma treatments, a Delphi consensus statement was performed. In this study, glaucoma experts and ocular surface disease experts reached consensus on the key factors to consider when designing such studies (II). The hope is to have more studies with comparable endpoints that can systematically show the potentially adverse effects of BAK. The preclinical studies in the current Ph.D. research focus on conjunctival goblet cells (GCs). GCs are important for the ocular surface because they release the mucin MUC5AC, which is an essential component of the inner layer of the tear film. BAK preservation may damage the GCs and result in a low GC density, leading to an unstable tear film and DED. The most commonly used IOP-lowering drugs are prostaglandin analogs (PGAs). Thus, the conducted studies investigate the effect of PGAs preserved in different ways on GCs. BAK-preserved latanoprost is cytotoxic to primary cultured human conjunctival GCs and results in a scattered expression of MUC5AC, in contrast to negative controls, where MUC5AC is localized around the cell nucleus (III). Preservative-free (PF) latanoprost is not cytotoxic and does not affect the MUC5AC expression pattern. Furthermore, BAK-preserved travoprost is found to be cytotoxic in a time-dependent manner, while Polyquad®-preserved travoprost does not affect GC survival at any measured time point (IV). Both Polyquad and BAK induce scattered expression of MUC5AC. The cytotoxicity of BAK-preserved PGA eye drops is higher compared to the safer profile of PF and Polyquad-preserved PGA eye drops (V). Additionally, PF latanoprost does not increase the release of the inflammatory markers interleukin (IL)-6 and IL-8, unlike BAK-preserved latanoprost. A review highlights the active and inactive components of IOP-lowering eye drops (VI). Several preclinical and clinical studies have identified adverse effects of BAK. Although other components, such as the active drug and phosphates, can also cause adverse events, the review clearly states that BAK alone is a major source of decreased tolerability. The conclusion of this thesis is that BAK preservation is unnecessary and harmful to the ocular surface. The preclinical studies demonstrate that GCs die when exposed to BAK. Furthermore, they find that BAK induces a pro-inflammatory response. The review included in the thesis concludes that BAK should be phased out of eye drops for chronic use. Overall, the inclusion of BAK poses a risk of developing DED and poor adherence, which can ultimately lead to disease progression and blindness.

Association between Dysbiosis in the Gut Microbiota of Primary Osteoporosis Patients and Bone Loss

In recent decades, gut microbiome research has experienced significant growth, driven by technological advances that enable quantifying bacterial taxa with greater precision. Age, diet, and living environment have emerged as three key factors influencing gut microbes. Dysbiosis, resulting from alterations in these factors, may lead to changes in bacterial metabolites that regulate pro- and anti-inflammatory processes and consequently impact bone health. Restoration of a healthy microbiome signature could mitigate inflammation and potentially reduce bone loss associated with osteoporosis or experienced by astronauts during spaceflight. However, current research is hindered by contradictory findings, insufficient sample sizes, and inconsistency in experimental conditions and controls. Despite progress in sequencing technology, defining a healthy gut microbiome across global populations remains elusive. Challenges persist in identifying accurate gut bacterial metabolics, specific taxa, and their effects on host physiology. We suggest greater attention be directed towards this issue in Western countries as the cost of treating osteoporosis in the United States reaches billions of dollars annually, with expenses projected to continue rising.