Immunoglobulin A and the microbiome

Genistein Promotes M2 Macrophage Polarization via Aryl Hydrocarbon Receptor and Alleviates Intestinal Inflammation in Broilers with Necrotic Enteritis

The aryl hydrocarbon receptor (AhR) is a transcription factor that regulates the immune system through complicated transcriptional programs. Genistein, an AhR ligand, exhibits anti-inflammatory properties. However, its role in modulating immune responses via the AhR signaling pathway remains unclear. In this study, 360 male Arbor Acre broilers (1-day-old) were fed a basal diet supplemented with 40 or 80 mg/kg genistein and infected with or without Clostridium perfringens (Cp). Our results demonstrated that genistein ameliorated Cp-induced intestinal damage, as reflected by the reduced intestinal lesion scores and improved intestinal morphology and feed-to-gain ratio. Moreover, genistein increased intestinal sIgA, TGF-β, and IL-10, along with elevated serum IgG, IgA, and lysozyme levels. Genistein improved intestinal AhR and cytochrome P450 family 1 subfamily A member 1 (CYP1A1) protein levels and AhR+ cell numbers in Cp-challenged broilers. The increased number of AhR+CD163+ cells in the jejunum suggested a potential association between genistein-induced AhR activation and anti-inflammatory effects mediated through M2 macrophage polarization. In IL-4-treated RAW264.7 cells, genistein increased the levels of AhR, CYP1A1, CD163, and arginase (Arg)-1 proteins, as well as IL-10 mRNA levels. This increase was attenuated by the AhR antagonist CH223191. In summary, genistein activated the AhR signaling pathway in M2 macrophages, which enhanced the secretion of anti-inflammatory cytokines and attenuated intestinal damage in Cp-infected broilers Cp.

Unraveling host regulation of gut microbiota through the epigenome-microbiome axis

Recent studies of dynamic interactions between epigenetic modifications of a host organism and the composition or activity of its associated gut microbiota suggest an opportunity for the host to shape its microbiome through epigenetic alterations that lead to changes in gene expression and noncoding RNA activity. We use insights from microbiota-induced epigenetic changes to review the potential of the host to epigenetically regulate its gut microbiome, from which a bidirectional 'epigenome-microbiome axis' emerges. This axis embeds environmentally induced variation, which may influence the adaptive evolution of host-microbe interactions. We furthermore present our perspective on how the epigenome-microbiome axis can be understood and investigated within a holo-omic framework with potential applications in the applied health and food sciences.

Prebiotic fiber blend supports growth and development and favorable digestive health in puppies

Introduction

A healthy gastrointestinal (GI) microbiome has been shown to be essential for proper nutrient absorption and metabolism, maintenance of intestinal epithelial integrity and osmolarity, gut immunomodulation, and overall health. One of the most effective ways to promote a healthy GI microbiome is through dietary interventions, such as the addition of prebiotics. Prebiotics are substrates that are selectively utilized by the host GI microbiome through fermentation to confer a health benefit. However, research on prebiotics in companion animals is limited, especially in growing animals. Thus, this study was conducted to assess the effects of a novel prebiotic fiber blend on key parameters related to intestinal health and growth in puppies.

Methods

Twenty-two puppies at least 4 months of age but not older than 10 months were fed a commercially available dry food during a prefeed period, and then fed a similarly formulated test food with the addition of the prebiotic fiber blend for a minimum of 90 days. Serum and fecal samples were collected at the end of the prefeed period and throughout the test period.

Results

Puppies fed the test food grew as expected for puppies of this age. Complete blood count and serum chemistry analyses were clinically normal for all animals. Fecal score increased linearly, fecal moisture decreased linearly, and pH exhibited a cubic trend throughout the study duration. There was a linear increase in short-chain fatty acids throughout the study, which is associated with favorable digestive and overall health. The inflammatory cytokine interleukin-7 decreased linearly and interleukin-18 trended towards linear decrease.

Conclusion

This study showed that puppies continued to grow and develop normally, and experienced serum and stool characteristics indicative of improved GI health when fed a growth food fortified with a novel prebiotic fiber blend. Furthermore, these results contribute to the overall understanding of the effects of prebiotics on the GI health of growing companion animals.

Revitalizing the Gut Microbiome in Chronic Kidney Disease: A Comprehensive Exploration of the Therapeutic Potential of Physical Activity

Both physical inactivity and disruptions in the gut microbiome appear to be prevalent in patients with chronic kidney disease (CKD). Engaging in physical activity could present a novel nonpharmacological strategy for enhancing the gut microbiome and mitigating the adverse effects associated with microbial dysbiosis in individuals with CKD. This narrative review explores the underlying mechanisms through which physical activity may favorably modulate microbial health, either through direct impact on the gut or through interorgan crosstalk. Also, the development of microbial dysbiosis and its interplay with physical inactivity in patients with CKD are discussed. Mechanisms and interventions through which physical activity may restore gut homeostasis in individuals with CKD are explored.

Tlr9 deficiency in B cells leads to obesity by promoting inflammation and gut dysbiosis

Toll-like receptor 9 (TLR9) recognizes bacterial, viral and self DNA and play an important role in immunity and inflammation. However, the role of TLR9 in obesity is less well-studied. Here, we generate B-cell-specific Tlr9-deficient (Tlr9fl/fl/Cd19Cre+/-, KO) B6 mice and model obesity using a high-fat diet. Compared with control mice, B-cell-specific-Tlr9-deficient mice exhibited increased fat tissue inflammation, weight gain, and impaired glucose and insulin tolerance. Furthermore, the frequencies of IL-10-producing-B cells and marginal zone B cells were reduced, and those of follicular and germinal center B cells were increased. This was associated with increased frequencies of IFNγ-producing-T cells and increased follicular helper cells. In addition, gut microbiota from the KO mice induced a pro-inflammatory state leading to immunological and metabolic dysregulation when transferred to germ-free mice. Using 16 S rRNA gene sequencing, we identify altered gut microbial communities including reduced Lachnospiraceae, which may play a role in altered metabolism in KO mice. We identify an important network involving Tlr9, Irf4 and Il-10 interconnecting metabolic homeostasis, with the function of B and T cells, and gut microbiota in obesity.

Microbiome and infectious disease: diagnostics to therapeutics

Over 300 years of research on the microbial world has revealed their importance in human health and disease. This review explores the impact and potential of microbial-based detection methods and therapeutic interventions, integrating research of early microbiologists, current findings, and future perspectives.

Intestinal Mucosal Immune Barrier: A Powerful Firewall Against Severe Acute Pancreatitis-Associated Acute Lung Injury via the Gut-Lung Axis

The pathogenesis of severe acute pancreatitis-associated acute lung injury (SAP-ALI), which is the leading cause of mortality among hospitalized patients in the intensive care unit, remains incompletely elucidated. The intestinal mucosal immune barrier is a crucial component of the intestinal epithelial barrier, and its aberrant activation contributes to the induction of sustained pro-inflammatory immune responses, paradoxical intercellular communication, and bacterial translocation. In this review, we firstly provide a comprehensive overview of the composition of the intestinal mucosal immune barrier and its pivotal roles in the pathogenesis of SAP-ALI. Secondly, the mechanisms of its crosstalk with gut microbiota, which is called gut-lung axis, and its effect on SAP-ALI were summarized. Finally, a number of drugs that could enhance the intestinal mucosal immune barrier and exhibit potential anti-SAP-ALI activities were presented, including probiotics, glutamine, enteral nutrition, and traditional Chinese medicine (TCM). The aim is to offer a theoretical framework based on the perspective of the intestinal mucosal immune barrier to protect against SAP-ALI.

L-Theanine alleviates heat stress through modulation of gut microbiota and immunity

BACKGROUND

Heat stress (HS) damages the intestines, disrupting gut microbiota and immune balance. l-Theanine (LTA), found in tea, alleviates oxidative stress and cell apoptosis under HS; however, its effects on gut microbiota and immunity under HS remain unclear. To investigate this, we administered LTA doses of 100, 200, and 400 mg·kg-1 ·d-1 to C57BL/6J mice. On day 44, the model group and LTA intervention group were subjected to continuous 7-day HS treatment for 2 h per day.

RESULTS

The results demonstrated that LTA intervention improved food intake, body weight, and intestinal epithelium, and reduced the water intake of heat-stressed mice. It increased the abundance of Turicibacter, Faecalibaculum, Bifidobacterium, and norank_f_Muribaculaceae, while reducing that of Lachnoclostridium and Desulfovibrio. LTA intervention also increased the concentrations of amino acid and lipid metabolites, regulated macrophage differentiation stimulated by gut microbiota and metabolites, reduced the antigen presentation by macrophages to the specific immune system, promoted B-cell differentiation and sIgA secretion, inhibited pro-inflammatory factors, and enhanced intestinal defense. Mechanistically, LTA downregulated heat shock protein 70 expression and the TLR4/NF-κB/p38 MAPK signaling pathway, restoring gut microbiota and immune balance.

CONCLUSION

We suggest that LTA can alleviate HS by modulating gut microbiota, metabolites, and immunity, indicating its potential as a natural active ingredient for anti-HS food products. © 2023 Society of Chemical Industry.

Antimicrobial Properties of Colostrum and Milk

The growing number of antibiotic resistance genes is putting a strain on the ecosystem and harming human health. In addition, consumers have developed a cautious attitude towards chemical preservatives. Colostrum and milk are excellent sources of antibacterial components that help to strengthen the immunity of the offspring and accelerate the maturation of the immune system. It is possible to study these important defenses of milk and colostrum, such as lactoferrin, lysozyme, immunoglobulins, oligosaccharides, etc., as biotherapeutic agents for the prevention and treatment of numerous infections caused by microbes. Each of these components has different mechanisms and interactions in various places. The compound's mechanisms of action determine where the antibacterial activity appears. The activation of the antibacterial activity of milk and colostrum compounds can start in the infant's mouth during lactation and continue in the gastrointestinal regions. These antibacterial properties possess potential for therapeutic uses. In order to discover new perspectives and methods for the treatment of bacterial infections, additional investigations of the mechanisms of action and potential complexes are required.

A DNA vaccine against GII.4 human norovirus VP1 induces blocking antibody production and T cell responses

Human noroviruses (HuNoVs) are highly contagious and a leading cause of epidemics of acute gastroenteritis worldwide. Among the various HuNoV genotypes, GII.4 is the most prevalent cause of outbreaks. However, no vaccines have been approved for HuNoVs to date. DNA vaccines are proposed to serve as an ideal platform against HuNoV since they can be easily produced and customized to express target proteins. In this study, we constructed a CMV/R vector expressing a major structural protein, VP1, of GII.4 HuNoV (CMV/R-GII.4 HuNoV VP1). Transfection of CMV/R-GII.4 HuNoV VP1 into human embryonic kidney 293T (HEK293T) cells resulted in successful expression of VP1 proteins in vitro. Intramuscular or intradermal immunization of mice with the CMV/R-GII.4 HuNoV VP1 construct elicited the production of blocking antibodies and activation of T cell responses against GII.4 HuNoV VP1. Our collective data support the utility of CMV/R-GII.4 HuNoV VP1 as a promising DNA vaccine candidate against GII.4 HuNoV.

A new perspective on gut-lung axis affected through resident microbiome and their implications on immune response in respiratory diseases

The highly diverse microbial ecosystem of the human body colonizes the gastrointestinal tract has a profound impact on the host's immune, metabolic, endocrine, and other physiological processes, which are all interconnected. Specifically, gut microbiota has been found to play a crucial role in facilitating the adaptation and initiation of immune regulatory response through the gastrointestinal tract affecting the other distal mucosal sites such as lungs. A tightly regulated lung-gut axis during respiratory ailments may influence the various molecular patterns that instructs priming the disease severity to dysregulate the normal function. This review provides a comprehensive summary of current research on gut microbiota dysbiosis in respiratory diseases including asthma, pneumonia, bronchopneumonia, COPD during infections and cancer. A complex-interaction among gut microbiome, associated metabolites, cytokines, and chemokines regulates the protective immune response activating the mucosal humoral and cellular response. This potential mechanism bridges the regulation patterns through the gut-lung axis. This paper aims to advance the understanding of the crosstalk of gut-lung microbiome during infection, could lead to strategize to modulate the gut microbiome as a treatment plan to improve bad prognosis in various respiratory diseases.

Fecal virus transplantation has more moderate effect than fecal microbiota transplantation on changing gut microbial structure in broiler chickens

Growing evidence of fecal microbiota transplantation (FMT) and fecal virus transplantation (FVT) provides a possibility to regulate animal health, whereas little is known about the impact of the 2 methods. This study aimed to investigate the effects of gut microbes on jejunal function in healthy broiler chickens, with the objective of establishing a theoretical basis for the application of FMT and FVT. Cecal feces from 28-day-old AA broilers were collected to prepare gavage juice for FMT and FVT. FMT for Group FM, FVT for group FV and PBS gavage for group CON, continuously treated for 6 days start at 5-day-old chicks. Samples were collected at d 11 and d 21. The results showed that the treatment d 2 and the overall fecal score in treatment groups were significantly lower than CON group (P < 0.05). The jejunum morphology showed that FMT increased crypt depth, decreased villus height, V/C (P < 0.05) and FVT increased villus height (P < 0.05) at d 11. At d 21, villus height and crypt depth significantly higher (P < 0.05) in group FM and group FV. The expression of Claudin1, Occludin, ZO2, and Muc2 in the FV group was significantly increased (P < 0.05) at 11-day-old. FMT increased the secretion of sIgA at 11-day-old, and this influence lasted up to 21-day-old (P < 0.05). At 11-day-old, the expression of b0+AT of basic amino acid transport carrier and chymotrypsin activity (P < 0.05) had a significant correlation. At 21 d of age, FVT significantly increased the expression of PepT1 and SGLT1 (P < 0.05). At 11-day-old, FM group showed significantly higher faith pd index (P = 0.004) and Shannon index (P = 0.037), and separated from FV and CON according to PCoA. Among differentiating bacteria, Bacteroides significantly enriched (P < 0.05) in group FM, which positively correlated with the expression of ZO2, Muc2, Occludin, and Claudin1; R_Ruminococcus, L_Ruminococcus, Butyricicoccuss significantly enriched (P < 0.05) in group CON, which significantly higher than processing groups, R_Ruminococcus and L_Ruminococcus negatively correlated with the expression of Occludin (P < 0.05), and R_Ruminococcus, Butyricicoccus negatively correlated with the expression of Claudin1 (P < 0.05). At 21-day-old, PCoA based on Bray-Curtis shows that microbes taxa of 3 groups are isolated with each other and treatment groups were significant different with CON group based on Unweighted UniFrac and weighted UniFrac. The expression of PepT1 was significantly negatively (P < 0.05) correlated with Ruminococcus, and the expression of sIgA was significantly negatively (P < 0.05) correlated with Parabacteroides. In conclusion, FMT regulated intestinal flora rapidly, while it had little effect on intestinal function and a higher potential damaging risk on jejunal. FVT regulated intestinal flora structure softer, improved tight junction expression, but the mechanism of action needs further exploration.

The distribution and function of teleost IgT

Given the uniquely close relationship between fish and aquatic environments, fish mucosal tissues are constantly exposed to a wide array of pathogenic microorganisms in the surrounding water. To maintain mucosal homeostasis, fish have evolved a distinct mucosal immune system known as mucosal-associated lymphoid tissues (MALTs). These MALTs consist of key effector cells and molecules from the adaptive immune system, such as B cells and immunoglobulins (Igs), which play crucial roles in maintaining mucosal homeostasis and defending against external pathogen infections. Until recently, three primary Ig isotypes, IgM, IgD, and IgT, have been identified in varying proportions within the mucosal secretions of teleost fish. Similar to the role of mucosal IgA in mammals and birds, teleost IgT plays a predominant role in mucosal immunity. Following the identification of the IgT gene in 2005, significant advances have been made in researching the origin, evolution, structure, and function of teleost IgT. Multiple IgT variants have been identified in various species of teleost fish, underscoring the remarkable complexity of IgT in fish. Therefore, this study provides a comprehensive review of the recent advances in various aspects of teleost IgT, including its genomic and structural features, the diverse distribution patterns within various fish mucosal tissues (the skin, gills, gut, nasal, buccal, pharyngeal, and swim bladder mucosa), its interaction with mucosal symbiotic microorganisms, and its immune responses towards diverse pathogens, including bacteria, viruses, and parasites. We also highlight the existing research gaps in the study of teleost IgT, suggesting the need for further investigation into the functional aspects of IgT and IgT+ B cells. This research is aimed at providing valuable insights into the immune functions of IgT and the mechanisms underlying the immune responses of fish against infections.

Development of Orally Ingestible IgA Antibody Drugs to Maintain Symbiosis Between Humans and Microorganisms

In recent years, dysbiosis, abnormalities in the gut microbiota, has been reported to be associated with the development of many diseases, and improving the gut microbiota is important for health maintenance. It has been shown that the host recognizes and regulates intestinal bacteria by means of IgA antibodies secreted into the gut, but the precise nature of the commensal gut bacteria recognized by each IgA antibody is unclear. We have cloned monoclonal IgA antibodies from mouse intestinal IgA-producing cells and are searching for bacterial molecules recognized by each IgA clone. Although the interaction of IgA antibodies with intestinal bacteria is still largely unknown and requires further basic research, we discuss the potential use of orally ingestible IgA antibodies as agents to improve intestinal microbiota.

Mucosal IgA immune complex induces immunomodulatory responses in allergic airway and intestinal TH2 disease

BACKGROUND

IgA is the most abundant immunoglobulin at the mucosal surface and although its role in regulating mucosal immunity is not fully understood, its presence is associated with protection from developing allergic disease.

OBJECTIVE

We sought to determine the role of IgA immune complexes for therapeutic application to mucosal allergic responses.

METHODS

Trinitrophenol (TNP)-specific IgA immune complexes were applied, using TNP-coupled ovalbumin (OVA), to airway and gut mucosal surfaces in systemically sensitized allergic animals to regulate allergen challenge responses. Animals were assessed for both pathologic and immune-mediated responses in the lung and gut, respectively, using established mouse models.

RESULTS

The mucosal application of IgA immune complexes in the lung and gut with TNP-OVA regulated TH2-driven allergic response in the lung and gut, reducing TH2 cytokines and mucus (lung) as well as diarrhea and temperature loss (gut), but increasing IL-10 and the number of regulatory T cells. The IgA-OVA immune complex did not alter peanut-induced anaphylaxis, indicating antigen specificity. Using OVA-specific DO.11-green fluorescent protein IL-4 reporter mouse-derived TH2-skewed cells in a transfer model demonstrated that mucosal IgA immune complex treatment reduced TH2-cell expansion and increased the number of regulatory T cells. To address a potential mechanism of action, TGF-β and IL-10 were induced in bone marrow-derived dendritic cells when they were exposed to IgA immune complex, suggesting a regulatory phenotype induced in dendritic cells that also led to an altered primary T-cell-mediated response in in vitro OVA-specific assays.

CONCLUSIONS

These studies highlight one possible mechanism of how allergen-specific IgA may provide a regulatory signal to reduce the development of allergic responses in the lung and gut.

Gut commensals and their metabolites in health and disease

Purpose of review

This review comprehensively discusses the role of the gut microbiome and its metabolites in health and disease and sheds light on the importance of a holistic approach in assessing the gut.

Recent findings

The gut microbiome consisting of the bacteriome, mycobiome, archaeome, and virome has a profound effect on human health. Gut dysbiosis which is characterized by perturbations in the microbial population not only results in gastrointestinal (GI) symptoms or conditions but can also give rise to extra-GI manifestations. Gut microorganisms also produce metabolites (short-chain fatty acids, trimethylamine, hydrogen sulfide, methane, and so on) that are important for several interkingdom microbial interactions and functions. They also participate in various host metabolic processes. An alteration in the microbial species can affect their respective metabolite concentrations which can have serious health implications. Effective assessment of the gut microbiome and its metabolites is crucial as it can provide insights into one's overall health.

Summary

Emerging evidence highlights the role of the gut microbiome and its metabolites in health and disease. As it is implicated in GI as well as extra-GI symptoms, the gut microbiome plays a crucial role in the overall well-being of the host. Effective assessment of the gut microbiome may provide insights into one's health status leading to more holistic care.

Microbial sensing in the intestine

The gut microbiota plays a key role in host health and disease, particularly through their interactions with the immune system. Intestinal homeostasis is dependent on the symbiotic relationships between the host and the diverse gut microbiota, which is influenced by the highly co-evolved immune-microbiota interactions. The first step of the interaction between the host and the gut microbiota is the sensing of the gut microbes by the host immune system. In this review, we describe the cells of the host immune system and the proteins that sense the components and metabolites of the gut microbes. We further highlight the essential roles of pattern recognition receptors (PRRs), the G protein-coupled receptors (GPCRs), aryl hydrocarbon receptor (AHR) and the nuclear receptors expressed in the intestinal epithelial cells (IECs) and the intestine-resident immune cells. We also discuss the mechanisms by which the disruption of microbial sensing because of genetic or environmental factors causes human diseases such as the inflammatory bowel disease (IBD).

Alterations in the gut microbiome and its metabolites are associated with the immune response to mucosal immunization with Lactiplantibacillus plantarum-displaying recombinant SARS-CoV-2 spike epitopes in mice

Lactic acid bacteria (LAB) expressing foreign antigens have great potential as mucosal vaccines. Our previous study reported that recombinant Lactiplantibacillus plantarum SK156 displaying SARS-CoV-2 spike S1 epitopes elicited humoral and cell-mediated immune responses in mice. Here, we further examined the effect of the LAB-based mucosal vaccine on gut microbiome composition and function, and gut microbiota-derived metabolites. Forty-nine (49) female BALB/c mice were orally administered L. plantarum SK156-displaying SARS-CoV-2 spike S1 epitopes thrice (at 14-day intervals). Mucosal immunization considerably altered the gut microbiome of mice by enriching the abundance of beneficial gut bacteria, such as Muribaculaceae, Mucispirillum, Ruminococcaceae, Alistipes, Roseburia, and Clostridia vadinBB60. Moreover, the predicted function of the gut microbiome showed increased metabolic pathways for amino acids, energy, carbohydrates, cofactors, and vitamins. The fecal concentration of short-chain fatty acids, especially butyrate, was also altered by mucosal immunization. Notably, alterations in gut microbiome composition, function, and butyrate levels were positively associated with the immune response to the vaccine. Our results suggest that the gut microbiome and its metabolites may have influenced the immunogenicity of the LAB-based SARS-CoV-2 vaccine.

Stability and heterogeneity in the antimicrobiota reactivity of human milk-derived immunoglobulin A

Immunoglobulin A (IgA) is secreted into breast milk and is critical for both protecting against enteric pathogens and shaping the infant intestinal microbiota. The efficacy of breast milk-derived maternal IgA (BrmIgA) is dependent upon its specificity; however, heterogeneity in BrmIgA binding ability to the infant microbiota is not known. Using a flow cytometric array, we analyzed the reactivity of BrmIgA against bacteria common to the infant microbiota and discovered substantial heterogeneity between all donors, independent of preterm or term delivery. Surprisingly, we also observed intradonor variability in the BrmIgA response to closely related bacterial isolates. Conversely, longitudinal analysis showed that the antibacterial BrmIgA reactivity was relatively stable through time, even between sequential infants, indicating that mammary gland IgA responses are durable. Together, our study demonstrates that the antibacterial BrmIgA reactivity displays interindividual heterogeneity but intraindividual stability. These findings have important implications for how breast milk shapes the development of the preterm infant microbiota and protects against necrotizing enterocolitis.

Microbial Reprogramming in Obsessive-Compulsive Disorders: A Review of Gut-Brain Communication and Emerging Evidence

Obsessive-compulsive disorder (OCD) is a debilitating mental health disorder characterized by intrusive thoughts (obsessions) and repetitive behaviors (compulsions). Dysbiosis, an imbalance in the gut microbial composition, has been associated with various health conditions, including mental health disorders, autism, and inflammatory diseases. While the exact mechanisms underlying OCD remain unclear, this review presents a growing body of evidence suggesting a potential link between dysbiosis and the multifaceted etiology of OCD, interacting with genetic, neurobiological, immunological, and environmental factors. This review highlights the emerging evidence implicating the gut microbiota in the pathophysiology of OCD and its potential as a target for novel therapeutic approaches. We propose a model that positions dysbiosis as the central unifying element in the neurochemical, immunological, genetic, and environmental factors leading to OCD. The potential and challenges of microbial reprogramming strategies, such as probiotics and fecal transplants in OCD therapeutics, are discussed. This review raises awareness of the importance of adopting a holistic approach that considers the interplay between the gut and the brain to develop interventions that account for the multifaceted nature of OCD and contribute to the advancement of more personalized approaches.

Bibliometric visualization analysis of gut-kidney axis from 2003 to 2022

Background: The gut-kidney axis refers to the interaction between the gastrointestinal tract and the kidneys, and its disorders have become increasingly important in the development of kidney diseases. The aim of this study is to identify current research hotspots in the field of the gut-kidney axis from 2003 to 2022 and provide guidance for future research in this field. Methods: We collected relevant literature on the gut-kidney axis from the Web of Science Core Collection (WoSCC) database and conducted bibliometric and visualization analyses using biblioshiny in R-Studio and VOSviewer (version 1.6.16). Results: A total of 3,900 documents were retrieved from the WoSCC database. The publications have shown rapid expansion since 2011, with the greatest research hotspot emerging due to the concept of the "intestinal-renal syndrome," first proposed by Meijers. The most relevant journals were in the field of diet and metabolism, such as Nutrients. The United States and China were the most influential countries, and the most active institute was the University of California San Diego. Author analysis revealed that Denise Mafra, Nosratola D. Vaziri, Fouque, and Denis made great contributions in different aspects of the field. Clustering analysis of the keywords found that important research priorities were "immunity," "inflammation," "metabolism," and "urinary toxin," reflecting the basis of research in the field. Current research frontiers in the field include "hyperuricemia," "gut microbiota," "diabetes," "trimethylamine n-oxide," "iga nephropathy," "acute kidney injury," "chronic kidney disease," "inflammation," all of which necessitate further investigation. Conclusion: This study presents a comprehensive bibliometric analysis and offers an up-to-date outlook on the research related to the gut-kidney axis, with a specific emphasis on the present state of intercommunication between gut microbiota and kidney diseases in this field. This perspective may assist researchers in selecting appropriate journals and partners, and help to gain a deeper understanding of the field's hotspots and frontiers, thereby promoting future research.

Flagellar-based motility accelerates IgA-mediated agglutination of Salmonella Typhimurium at high bacterial cell densities

Introduction

Secretory IgA (SIgA) protects the intestinal epithelium from enteric pathogens such as Salmonella enterica serovar Typhimurium (STm) through a process known as immune exclusion, where invading bacteria are aggregated via antibody cross-linking, encased in mucus, and then cleared from the intestinal tract via peristalsis. At high cell densities, the STm aggregates form a tightly packed network that is reminiscent of early bacterial biofilms. However, the underlying mechanism of how SIgA mediates this transition from a motile and invasive state to an avirulent sessile state in STm is currently unknown.

Methods

In this report, we developed and validated a methodology known as the "snow globe" assay to enable real-time imaging and quantification of STm agglutination by the mouse monoclonal IgA Sal4.

Results

We observed that agglutination in the snow globe assay was dose-dependent, antigen-specific, and influenced by antibody isotype. We determined that flagellar-based motility was a prerequisite for rapid onset of agglutination, even at high cell densities where cell-cell contacts are expected to be frequent. We also investigated the roles of individual cyclic-di-GMP metabolizing enzymes previously implicated in motility and biofilm formation in Sal4 IgA-mediated agglutination.

Discussion

Taken together, our results demonstrate that IgA-mediated agglutination is a dynamic process influenced by bacterial motility and cell-cell collisions. We conclude that the snow globe assay is a viable platform to further decipher the molecular and genetic determinants that drive this interaction.

Stability and heterogeneity in the anti-microbiota reactivity of human milk-derived Immunoglobulin A

Immunoglobulin A (IgA) is secreted into breast milk and is critical to both protecting against enteric pathogens and shaping the infant intestinal microbiota. The efficacy of breast milk-derived maternal IgA (BrmIgA) is dependent upon its specificity, however heterogeneity in BrmIgA binding ability to the infant microbiota is not known. Using a flow cytometric array, we analyzed the reactivity of BrmIgA against bacteria common to the infant microbiota and discovered substantial heterogeneity between all donors, independent of preterm or term delivery. We also observed intra-donor variability in the BrmIgA response to closely related bacterial isolates. Conversely, longitudinal analysis showed that the anti-bacterial BrmIgA reactivity was relatively stable through time, even between sequential infants, indicating that mammary gland IgA responses are durable. Together, our study demonstrates that the anti-bacterial BrmIgA reactivity displays inter-individual heterogeneity but intra-individual stability. These findings have important implications for how breast milk shapes the development of the infant microbiota and protects against Necrotizing Enterocolitis.

SUMMARY

We analyze the ability of breast milk-derived Immunoglobulin A (IgA) antibodies to bind the infant intestinal microbiota. We discover that each mother secretes into their breast milk a distinct set of IgA antibodies that are stably maintained over time.

Clec12a tempers inflammation while restricting expansion of a colitogenic commensal

Regulation of the microbiota is critical to intestinal health yet the mechanisms employed by innate immunity remain unclear. Here we show that mice deficient in the C-Type-lectin receptor, Clec12a developed severe colitis, which was dependent on the microbiota. Fecal-microbiota-transplantation (FMT) studies into germfree mice revealed a colitogenic microbiota formed within Clec12a -/- mice that was marked by expansion of the gram-positive organism, Faecalibaculum rodentium . Treatment with F. rodentium was sufficient to worsen colitis in wild-type mice. Macrophages within the gut express the highest levels of Clec12a. Cytokine and sequencing analysis in Clec12a -/- macrophages revealed heighten inflammation but marked reduction in genes associated with phagocytosis. Indeed, Clec12a -/- macrophages are impaired in their ability to uptake F. rodentium. Purified Clec12a had higher binding to gram-positive organisms such as F. rodentium . Thus, our data identifies Clec12a as an innate immune surveillance mechanism to control expansion of potentially harmful commensals without overt inflammation.

The efficacy of anti-proteolytic peptide R7I in intestinal inflammation, function, microbiota, and metabolites by multi-omics analysis in murine bacterial enteritis

Increased antibiotic resistance poses a major limitation in tackling inflammatory bowel disease and presents a large challenge for global health care. Antimicrobial peptides (AMPs) are a potential class of antimicrobial agents. Here, we have designed the potential oral route for antimicrobial peptide R7I with anti-proteolytic properties to deal with bacterial enteritis in mice. The results revealed that R7I protected the liver and gut from damage caused by inflammation. RNA-Seq analysis indicated that R7I promoted digestion and absorption in the small intestine by upregulating transmembrane transporter activity, lipid and small molecule metabolic processes and other pathways, in addition to upregulating hepatic steroid biosynthesis and fatty acid degradation. For the gut microbiota, Clostridia were significantly reduced in the R7I-treated group, and Odoribacteraceae, an efficient isoalloLCA-synthesizing strain, was the main dominant strain, protecting the gut from potential pathogens. In addition, we further discovered that R7I reduced the accumulation of negative organic acid metabolites. Overall, R7I exerted better therapeutic and immunomodulatory potential in the bacterial enteritis model, greatly reduced the risk of disease onset, and provided a reference for the in vivo application of antimicrobial peptides.

Longitudinal Study of the Effects of Flammulina velutipes Stipe Wastes on the Cecal Microbiota of Laying Hens

Because antibiotics have been phased out of use in poultry feed, measures to improve intestinal health have been sought. Dietary fiber may be beneficial to intestinal health by modulating gut microbial composition, but the exact changes it induces remain unclear. In this study, we evaluated the effect of Flammulina velutipes stipe wastes (FVW) on the cecal microbiotas of laying chickens at ages spanning birth to 490 days. Using clonal sequencing and 16S rRNA high-throughput sequencing, we showed that FVW improved the microbial diversity when they under fluctuated. The evolvement of the microbiota enhanced the physiological development of laying hens. Supplementation of FVW enriched the relative abundance of Sutterella, Ruminiclostridium, Synergistes, Anaerostipes, and Rikenellaceae, strengthened the positive connection between Firmicutes and Bacteroidetes, and increased the concentration of short-chain fatty acids (SCFAs) in early life. FVW maintains gut microbiota homeostasis by regulating Th1, Th2, and Th17 balance and secretory IgA (S-IgA) level. In conclusion, we showed that FVW induces microbial changes that are potentially beneficial for intestinal immunity. IMPORTANCE Dietary fiber is popularly used in poultry farming to improve host health and metabolism. Microbial composition is known to be influenced by dietary fiber use, although the exact FVW-induced changes remain unclear. This study provided a first comparison of the effects of FVW and the most commonly used antibiotic growth promoter (flavomycin) on the cecal microbiotas of laying hens from birth to 490 days of age. We found that supplementation with FVW altered cecal microbial composition, thereby affecting the correlation network between members of the microbiota, and subsequently affecting the intestinal immune homeostasis.

The direct correlation between microbiota and SARS-CoV-2 infectious disease

The human microbiota is the good part of the human organism and is a collection of symbiotic microorganisms which aid in human physiological functions. Diseases that can be generated by an altered microbiota are continuously being studied, but it is quite evident how a damaged microbiota is involved in chronic inflammatory diseases, psychiatric diseases, and some bacterial or viral infections. However, the role of the microbiota in the host immune response to bacterial and viral infections is still not entirely understood. Metabolites or components which are produced by the microbiota are useful in mediating microbiota-host interactions, thus influencing the host's immune capacity. Recent evidence shows that the microbiota is evidently altered in patients with viral infections such as post-acute COVID-19 syndrome (PACS). In this review, the associations between microbiota and COVID-19 infection are highlighted in terms of biological and clinical significance by emphasizing the mechanisms through which metabolites produced by the microbiota modulate immune responses to COVID-19 infection.

Association between microbiota and immune response to Sars-CoV-2 infection

In recent times, the key role of the human microbiota in the body's response to infectious diseases has been increasingly demonstrated. The human microbiota is the set of symbiotic microorganisms which coexist with the human organism without harming it. However, diseases related to the microbiota occur and are being studied, and numerous publications suggest that altered microbiota composition is implicated in psychiatric diseases, chronic inflammatory diseases, and some viral infections. On the other hand, the role of the human microbiota in the host immune response to viral infections is not entirely clear. Metabolites or components produced by the microbiota are the main mediators of microbiota-host interactions that influence host immunity. It has been shown that in patients with COVID-19 and post-acute COVID-19 syndrome (PACS), the microbiota is significantly altered. In this brief review, we examine the associations between the role of the microbiota in response to COVID-19 infection in terms of molecular biology and clinical relevance. We finally discuss the mechanisms by which metabolites produced by the microbiota modulate host immune responses to SARS-CoV-2 infection.

The Mechanism of Important Components in Canine Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is a potential treatment for many intestinal diseases. In dogs, FMT has been shown to have positive regulation effects in treating Clostridioides difficile infection (CDI), inflammatory bowel disease (IBD), canine parvovirus (CPV) enteritis, acute diarrhea (AD), and acute hemorrhagic diarrhea syndrome (AHDS). FMT involves transplanting the functional components of a donor's feces into the gastrointestinal tract of the recipient. The effective components of FMT not only include commensal bacteria, but also include viruses, fungi, bacterial metabolites, and immunoglobulin A (IgA) from the donor feces. By affecting microbiota and regulating host immunity, these components can help the recipient to restore their microbial community, improve their intestinal barrier, and induce anti-inflammation in their intestines, thereby affecting the development of diseases. In addition to the above components, mucin proteins and intestinal epithelial cells (IECs) may be functional ingredients in FMT as well. In addition to the abovementioned indications, FMT is also thought to be useful in treating some other diseases in dogs. Consequently, when preparing FMT fecal material, it is important to preserve the functional components involved. Meanwhile, appropriate fecal material delivery methods should be chosen according to the mechanisms these components act by in FMT.

Interactions of Microbiota and Mucosal Immunity in the Ceca of Broiler Chickens Infected with Eimeria tenella

The purpose of the study was to investigate the effects of Eimeria tenella infection on the cecal microbiome, the protein concentration of cecal content, cecal mucosal immunity, and serum endotoxin levels in broilers. Three hundred sixty 14-day-old broilers were allocated to five infection doses with six replicates. The five infection doses were: ID0: 0, ID1: 6250, ID2: 12,500, ID3: 25,000, and ID4: 50,000 Eimeria tenella oocysts. Eimeria tenella infection significantly increased the relative abundance of the phylum Proteobacteria, which includes diverse pathogenic bacteria, and significantly decreased the relative abundance of the phylum Firmicutes. Protein concentration of the cecal content was linearly increased (p < 0.05), and the concentration of secretory immunoglobulin A (sIgA) in the cecal content was linearly decreased by Eimeria tenella infection (p < 0.05). Goblet cell density was linearly reduced in the ceca by Eimeria tenella infection (p < 0.05). Eimeria tenella infection tended to linearly decrease the relative mRNA expression of antimicrobial peptide genes such as avian beta-defensin 9 (AvBD9; p = 0.10) and liver-expressed antimicrobial peptide 2 (LEAP2; p = 0.08) in the cecal tissue. Therefore, Eimeria tenella infection negatively modulated cecal microbiota via impairing cecal mucosal immunity and increasing protein concentration in the cecal content in broilers.

Clostridium butyricum potentially improves inflammation and immunity through alteration of the microbiota and metabolism of gastric cancer patients after gastrectomy

Background

Gastrectomy is the most effective treatment to improve the clinical survival rate of patients with gastric cancer. However, the pathophysiological changes caused by gastrectomy have seriously affected the postoperative recovery.

Methods

In the present trial, Ataining (containing C. butyricum, CGMCC0313.1) was applied in patients after gastrectomy to investigate the effect of C. butyricum on the early postoperative recovery by monitoring the inflammatory immune response with blood indicators, detecting the gut microbiota with high-throughput sequencing, and analyzing the short-chain fatty acids (SCFAs) with targeted metabolomics. This study is registered with the number ChiCTR2000040915.

Results

Our outcomes revealed that C. butyricum had significantly reduced the number of Leucocyte (P < 0.001), the percentage of Neutrophil (P < 0.001), the expression of IL-1β (P < 0.01), IL-6 (P < 0.05), and TNF-α (P < 0.01), while markedly enhanced the immunity indexes (immunoglobulin and lymphocyte) (P < 0.05) and nutrition indexes (albumin and total protein) (P < 0.05). In addition, the use of the C. butyricum greatly enriched the relative abundance of beneficial bacteria Bacteroides, Faecalibacterium and Gemmiger, while the abundance of pathogenic Streptococcus, Desulfovibrio and Actinomyces were markedly decreased at genus level. We also observed significant up-regulation of SCFAs, including acetic acid, propionic acid, butyric acid and isobutyric acid, after C. butyricum administration in patients receiving gastrectomy.

Conclusion

Therefore, evidence supported that oral administration of C. butyricum after gastrectomy can reduce early postoperative inflammation, enhance immune ability, restore intestinal microbiota eubiosis, increase intestinal SCFAs, reduce the occurrence of postoperative complications, and ultimately promote the early recovery of the patient.

Clinical trial registration

http://www.chictr.org.cn/, identifier (ChiCTR2000040915).

Sequestration of gut pathobionts in intraluminal casts, a mechanism to avoid dysregulated T cell activation by pathobionts

T cells that express the transcription factor RORγ, regulatory (Treg), or conventional (Th17) are strongly influenced by intestinal symbionts. In a genetic approach to identify mechanisms underlying this influence, we performed a screen for microbial genes implicated, in germfree mice monocolonized with Escherichia coli Nissle. The loss of capsule-synthesis genes impaired clonal expansion and differentiation of intestinal RORγ⁺ T cells. Mechanistic exploration revealed that the capsule-less mutants remained able to induce species-specific immunoglobulin A (IgA) and were highly IgA-coated. They could still trigger myeloid cells, and more effectively damaged epithelial cells in vitro. Unlike wild-type microbes, capsule-less mutants were mostly engulfed in intraluminal casts, large agglomerates composed of myeloid cells extravasated into the gut lumen. We speculate that sequestration in luminal casts of potentially harmful microbes, favored by IgA binding, reduces the immune system's actual exposure, preserving host-microbe equilibrium. The variable immunostimulation by microbes that has been charted in recent years may not solely be conditioned by triggering molecules or metabolites but also by physical limits to immune system exposure.

Agglutination of Borreliella burgdorferi by Transmission-Blocking OspA Monoclonal Antibodies and Monovalent Fab Fragments

Lyme disease vaccines based on recombinant Outer surface protein A (OspA) elicit protective antibodies that interfere with tick-to-host transmission of the disease-causing spirochete Borreliella burgdorferi. Another hallmark of OspA antisera and certain OspA monoclonal antibodies (MAbs) is their capacity to induce B. burgdorferi agglutination in vitro, a phenomenon first reported more than 30 years ago but never studied in molecular detail. In this report, we demonstrate that transmission-blocking OspA MAbs, individually and in combination, promote dose-dependent and epitope-specific agglutination of B. burgdorferi. Agglutination occurred within minutes and persisted for hours. Spirochetes in the core of the aggregates exhibited evidence of outer membrane (OM) stress, revealed by propidium iodide uptake. The most potent agglutinator was the mouse MAb LA-2, which targets the OspA C terminus (β-strands 18 to 20). Human MAb 319-44, which also targets the OspA C terminus (β-strand 20), and 857-2, which targets the OspA central β-sheet (strands 8 to 10), were less potent agglutinators, while MAb 221-7, which targets β-strands 10 to 11, had little to no measurable agglutinating activity, even though its affinity for OspA exceeded that of LA-2. Remarkably, monovalent Fab fragments derived from LA-2, and to a lesser degree 319-44, retained the capacity to induce B. burgdorferi aggregation and OM stress, a particularly intriguing observation considering that "LA-2-like" Fabs have been shown to experimentally entrap B. burgdorferi within infected ticks and prevent transmission during feeding to a mammalian host. It is therefore tempting to speculate that B. burgdorferi aggregation triggered by OspA-specific antibodies in vitro may in fact reflect an important biological activity in vivo.

Gut microbiome and breast-feeding: Implications for early immune development

Establishment of the gut microbiome during early life is a complex process with lasting implications for an individual's health. Several factors influence microbial assembly; however, breast-feeding is recognized as one of the most influential drivers of gut microbiome composition during infancy, with potential implications for function. Differences in gut microbial communities between breast-fed and formula-fed infants have been consistently observed and are hypothesized to partially mediate the relationships between breast-feeding and decreased risk for numerous communicable and noncommunicable diseases in early life. Despite decades of research on the gut microbiome of breast-fed infants, there are large scientific gaps in understanding how human milk has evolved to support microbial and immune development. This review will summarize the evidence on how breast-feeding broadly affects the composition and function of the early-life gut microbiome and discuss mechanisms by which specific human milk components shape intestinal bacterial colonization, succession, and function.

Immunoglobulin A antibody composition is sculpted to bind the self gut microbiome

Despite being the most abundantly secreted immunoglobulin isotype, the pattern of reactivity of immunoglobulin A (IgA) antibodies toward each individual's own gut commensal bacteria still remains elusive. By colonizing germ-free mice with defined commensal bacteria, we found that the binding specificity of bulk fecal and serum IgA toward resident gut bacteria resolves well at the species level and has modest strain-level specificity. IgA hybridomas generated from lamina propria B cells of gnotobiotic mice showed that most IgA clones recognized a single bacterial species, whereas a small portion displayed cross-reactivity. Orally administered hybridoma-produced IgAs still retained bacterial antigen binding capability, implying the potential for a new class of therapeutic antibodies. Species-specific IgAs had a range of strain specificities. Given the distinctive bacterial species and strain composition found in each individual's gut, our findings suggest the IgA antibody repertoire is shaped uniquely to bind "self" gut bacteria.

B cell-mediated regulatory mechanisms control tumor-promoting intestinal inflammation

Mechanisms underlying tumor-promoting inflammatory processes in colitis-associated colorectal cancer (CAC) remain largely elusive. Here, we provide genetic evidence for distinct B cell-mediated immunoregulatory mechanisms that protect from chronic colitis versus CAC. We demonstrate an inherent capacity of interleukin-10 (IL-10)-producing B cells to differentiate into immunoglobulin A (IgA) plasma cells (PCs) upon Toll-like receptor (TLR) activation. Our data show that B cell-derived IL-10 is essential to limit pathogenic T helper type 1 (Th1)/Th17 T cell responses during chronic colitis, while IgA PCs derived from IL-10⁺ B cells are being implicated in restraining tumorigenesis during CAC. Formation of a tumor-protective intestinal environment was associated with clonal expansion of specific types of colonic IgA PCs and development of an altered microbiota that attenuated CAC. We thus propose that regulatory B cell-mediated immunomodulation entails temporal release of IL-10, which is superseded by the generation of specific IgA affecting the microbial community, thereby controlling chronic inflammation and tumorigenesis in a distinctive but interrelated manner.

Mitochondrial complex I dysfunction alters the balance of soluble and membrane-bound TNF during chronic experimental colitis

Inflammatory bowel disease (IBD) is a complex, chronic, relapsing and heterogeneous disease induced by environmental, genomic, microbial and immunological factors. MCJ is a mitochondrial protein that regulates the metabolic status of macrophages and their response to translocated bacteria. Previously, an acute murine model of DSS-induced colitis showed increased disease severity due to MCJ deficiency. Unexpectedly, we now show that MCJ-deficient mice have augmented tumor necrosis factor α converting enzyme (TACE) activity in the context of chronic inflammation. This adaptative change likely affects the balance between soluble and transmembrane TNF and supports the association of the soluble form and a milder phenotype. Interestingly, the general shifts in microbial composition previously observed during acute inflammation were absent in the chronic model of inflammation in MCJ-deficient mice. However, the lack of the mitochondrial protein resulted in increased alpha diversity and the reduction in critical microbial members associated with inflammation, such as Ruminococcus gnavus, which could be associated with TACE activity. These results provide evidence of the dynamic metabolic adaptation of the colon tissue to chronic inflammatory changes mediated by the control of mitochondrial function.

A Meta-Analysis on the Efficacy and Safety of Bacterial Lysates in Chronic Obstructive Pulmonary Disease

Background

Chronic obstructive pulmonary disease (COPD) is a common and frequently encountered disease of respiratory apparatus and is vulnerable to infection. Increasing studies reveal that bacterial lysates play an encouraging role in preventing exacerbations in these patients. We here investigated the efficacy and safety of bacterial lysates in COPD.

Methods

We performed systematic research on PubMed, EMBASE, the Cochrane Library (CENTRAL), and Web of Science by using the keywords and their synonyms for studies published before January 11, 2022. Two researchers screened the studies of literature independently according to the inclusion and exclusion criteria and extracted data from the included studies. Another two researchers assessed the risk of bias of each included using the Cochrane risk-of-bias tool. Meta-analysis was conducted using R (version 4.1.1, The R Foundation for Statistical Computing) and Review Manager (version 5.4.0, The Cochrane Collaboration).

Results

A total of 12 studies were included in this meta-analysis, and the pooled results showed that bacterial lysates were effective to reduce exacerbation rate (overall: relative risk [RR] = 0.83, 95% confidence interval [CI] 0.72–0.96; alkaline bacterial lysate subgroup [OM-85]: RR = 0.87, 95% CI 0.77–0.98; mechanical bacterial lysate subgroup [Ismigen]: RR = 0.70, 95% CI 0.41–1.20) and mean number of exacerbations (overall: MD = −0.42, 95% CI −0.75 to −0.08; alkaline bacterial lysate subgroup [OM-85]: MD = −0.72, 95% CI −1.35 to −0.09; mechanical bacterial lysate subgroup [Ismigen]: MD = −0.02, 95% CI −0.21 to 0.17). Bacterial lysates were also found beneficial in alleviating symptoms. The side effects were acceptable and slight.

Conclusion

Bacterial lysates can benefit patients with COPD by reducing exacerbations and alleviating symptoms. OM-85 is the preferable product based on the existing evidence. Further studies are needed to validate these findings.

Systematic Review Registration

[www.crd.york.ac.uk/prospero/], identifier [CRD42022299420].

Interplay of gut microbiota and oxidative stress: Perspective on neurodegeneration and neuroprotection

Background

Recent research on the implications of gut microbiota on brain functions has helped to gather important information on the relationship between them. Pathogenesis of neurological disorders is found to be associated with dysregulation of gut-brain axis. Some gut bacteria metabolites are found to be directly associated with the increase in reactive oxygen species levels, one of the most important risk factors of neurodegeneration. Besides their morbid association, gut bacteria metabolites are also found to play a significant role in reducing the onset of these life-threatening brain disorders.

Aim of Review

Studies done in the recent past raises two most important link between gut microbiota and the brain: "gut microbiota-oxidative stress-neurodegeneration" and gut microbiota-antioxidant-neuroprotection. This review aims to gives a deep insight to our readers, of the collective studies done, focusing on the gut microbiota mediated oxidative stress involved in neurodegeneration along with a focus on those studies showing the involvement of gut microbiota and their metabolites in neuroprotection.

Key Scientific Concepts of Review

This review is focused on three main key concepts. Firstly, the mounting evidences from clinical and preclinical arenas shows the influence of gut microbiota mediated oxidative stress resulting in dysfunctional neurological processes. Therefore, we describe the potential role of gut microbiota influencing the vulnerability of brain to oxidative stress, and a budding causative in Alzheimer's and Parkinson's disease. Secondly, contributing roles of gut microbiota has been observed in attenuating oxidative stress and inflammation via its own metabolites or by producing secondary metabolites and, also modulation in gut microbiota population with antioxidative and anti-inflammatory probiotics have shown promising neuro resilience. Thirdly, high throughput in silico tools and databases also gives a correlation of gut microbiome, their metabolites and brain health, thus providing fascinating perspective and promising new avenues for therapeutic options.

The regulatory role of eosinophils in viral, bacterial, and fungal infections

Eosinophils are innate immune cells typically associated with allergic and parasitic diseases. However, in recent years, eosinophils have also been ascribed a role in keeping homeostasis and in fighting several infectious diseases. Indeed, these cells circulate as mature cells in the blood and can be quickly recruited to the infected tissue. Moreover, eosinophils have all the necessary cellular equipment such as pattern recognition receptors (PRRs), pro-inflammatory cytokines, anti-bacterial proteins, and DNA traps to fight pathogens and promote an efficient immune response. This review summarizes some of the updated information on the role of eosinophils' direct and indirect mediated interactions with pathogens.

Recent research on the effect of preeclampsia on maternal-infant intestinal flora interactions

Preeclampsia (PE) is a unique complication of pregnancy that affects the health of the mother and the infant. Intestinal flora plays an important regulatory role in human body's metabolism and immunity and is associated with many diseases. Studies have shown that the development and progression of PE can lead to alterations in intestinal flora in the mother and are even closely associated with the colonization and development of intestinal flora in the offspring. This article reviews related studies on the effect of PE on maternal-infant intestinal flora, so as to provide new ideas for the prevention and treatment of maternal and infant complications associated with PE.

[Microbiocenosis-regulating therapy of inflammatory pathology of the oropharynx]

Inflammatory pathology of the oropharynx, which does not lose its relevance, is a problem that is of interest to doctors of various specialties. As one of the main causes of inflammatory diseases of the pharynx, the influence of microorganisms, primarily viruses, on the mucous membrane of the upper respiratory tract is indicated. The authors of the article emphasize the importance of preserving the indigenous microbiota, which provides a barrier function and prevents the adhesion and colonization of pathogenic microorganisms. In this regard, the most effective and safe is local microbiocenosis-regulatory therapy using lysozyme, a natural peptide that has antiseptic, anti-inflammatory and immunoregulatory effects. As such a drug, the authors recommend the combined drug Lorolizin, which can be used in the treatment of acute pharyngitis, acute tonsillitis, and adenoiditis.

Epigenetic Modulation of Class-Switch DNA Recombination to IgA by miR-146a Through Downregulation of Smad2, Smad3 and Smad4

IgA is the predominant antibody isotype at intestinal mucosae, where it plays a critical role in homeostasis and provides a first line of immune protection. Dysregulation of IgA production, however, can contribute to immunopathology, particularly in kidneys in which IgA deposition can cause nephropathy. Class-switch DNA recombination (CSR) to IgA is directed by TGF-β signaling, which activates Smad2 and Smad3. Activated Smad2/Smad3 dimers are recruited together with Smad4 to the IgH α locus Iα promoter to activate germline Iα-Cα transcription, the first step in the unfolding of CSR to IgA. Epigenetic factors, such as non-coding RNAs, particularly microRNAs, have been shown to regulate T cells, dendritic cells and other immune elements, as well as modulate the antibody response, including CSR, in a B cell-intrinsic fashion. Here we showed that the most abundant miRNA in resting B cells, miR-146a targets Smad2, Smad3 and Smad4 mRNA 3'UTRs and keeps CSR to IgA in check in resting B cells. Indeed, enforced miR-146a expression in B cells aborted induction of IgA CSR by decreasing Smad levels. By contrast, upon induction of CSR to IgA, as directed by TGF-β, B cells downregulated miR-146a, thereby reversing the silencing of Smad2, Smad3 and Smad4, which, once expressed, led to recruitment of Smad2, Smad3 and Smad4 to the Iα promoter for activation of germline Iα-Cα transcription. Deletion of miR-146a in miR-146a-/- mice significantly increased circulating levels of steady state total IgA, but not IgM, IgG or IgE, and heightened the specific IgA antibody response to OVA. In miR-146a-/- mice, the elevated systemic IgA levels were associated with increased IgA+ B cells in intestinal mucosae, increased amounts of fecal free and bacteria-bound IgA as well as kidney IgA deposition, a hallmark of IgA nephropathy. Increased germline Iα-Cα transcription and CSR to IgA in miR-146a-/- B cells in vitro proved that miR-146a-induced Smad2, Smad3 and Smad4 repression is B cell intrinsic. The B cell-intrinsic role of miR-146a in the modulation of CSR to IgA was formally confirmed in vivo by construction and OVA immunization of mixed bone marrow μMT/miR-146a-/- chimeric mice. Thus, by inhibiting Smad2, Smad3 and Smad4 expression, miR-146a plays an important and B cell intrinsic role in modulation of CSR to IgA and the IgA antibody response.

Immunoglobulin A, an Active Liaison for Host-Microbiota Homeostasis

Mucosal surfaces in the gastrointestinal tract are continually exposed to native, commensal antigens and susceptible to foreign, infectious antigens. Immunoglobulin A (IgA) provides dual humoral responses that create a symbiotic environment for the resident gut microbiota and prevent the invasion of enteric pathogens. This review features recent immunological and microbial studies that elucidate the underlying IgA and microbiota-dependent mechanisms for mutualism at physiological conditions. IgA derailment and concurrent microbiota instability in pathological diseases are also discussed in detail. Highlights of this review underscore that the source of IgA and its structural form can dictate microbiota reactivity to sustain a diverse niche where both host and bacteria benefit. Other important studies emphasize IgA insufficiency can result in the bloom of opportunistic pathogens that encroach the intestinal epithelia and disseminate into circulation. The continual growth of knowledge in these subjects can lead to the development of therapeutics targeting IgA and/or the microbiota to treat life threatening diseases.

Dose effect of bovine lactoferrin fortification on diarrhea and respiratory tract infections in weaned infants with anemia: A randomized, controlled trial

OBJECTIVE

The aim of this study was to explore the dose effect of bovine lactoferrin (bLF) fortification on the morbidity of diarrhea and respiratory tract infections in weaned infants with anemia.

METHODS

A total of 108 infants with anemia, who were exclusively breast fed at 4 to 6 mo and weaned and formula fed at 6 to 9 mo, were recruited. The eligible infants were randomly assigned to fortified group 0 (FG0), fortified group 1 (FG1), or fortified group 2 (FG2) and were given formula fortified with 0 mg/100 g, 38 mg/100 g, and 76 mg/100 g of bLF, respectively, for 3 mo. The morbidity of diarrhea and respiratory tract infections (RTIs), the duration of respiratory and diarrhea-related illnesses, and the levels of fecal human beta-defensin 2 (HBD-2), cathelicidin LL-37 (LL-37), secretory IgA (sIgA), butyrate, and calprotectin were assessed.

RESULTS

After the exclusion of 12 dropouts, the primary outcome measures, including episodes and duration of diarrhea and RTIs during the intervention, were obtained from 96 infants (35, 33, and 28 in FG0, FG1, and FG2, respectively). Compared with infants in FG0, there was a lower morbidity of rhinorrhea, wheezing, and skin rash among infants in FG1 (P < 0.05) and a lower morbidity of respiratory-related illness and wheezing among infants in FG2 (P < 0.05). Furthermore, a lower morbidity of diarrhea-related illness, diarrhea, vomiting, and nausea was observed among infants in FG2 than those in the other two groups (P < 0.05). In addition, the FG1 infants had a lower morbidity of vomiting and nausea than the FG0 infants (P < 0.05). The HBD-2, LL-37, sIgA, and calprotectin levels were significantly higher whereas the butyrate level was significantly lower in the FG2 infants than in infants in the other two groups after 3 mo of intervention (P < 0.05).

CONCLUSIONS

The bLF-fortified formula was effective in reducing the morbidity of diarrhea and RTIs in infants with anemia, with the 76 mg/100 g bLF-fortified formula exhibiting a stronger effect. The bLF fortification could be a new strategy for the prevention of diarrhea and RTIs in infants with anemia.

The Gut-Liver Axis in Cholestatic Liver Diseases

The gut-liver axis describes the physiological interplay between the gut and the liver and has important implications for the maintenance of health. Disruptions of this equilibrium are an important factor in the evolution and progression of many liver diseases. The composition of the gut microbiome, the gut barrier, bacterial translocation, and bile acid metabolism are the key features of this cycle. Chronic cholestatic liver diseases include primary sclerosing cholangitis, the generic term secondary sclerosing cholangitis implying the disease secondary sclerosing cholangitis in critically ill patients and primary biliary cirrhosis. Pathophysiology of these diseases is not fully understood but seems to be multifactorial. Knowledge about the alterations of the gut-liver axis influencing the pathogenesis and the outcome of these diseases has considerably increased. Therefore, this review aims to describe the function of the healthy gut-liver axis and to sum up the pathological changes in these cholestatic liver diseases. The review compromises the actual level of knowledge about the gut microbiome (including the mycobiome and the virome), the gut barrier and the consequences of increased gut permeability, the effects of bacterial translocation, and the influence of bile acid composition and pool size in chronic cholestatic liver diseases. Furthermore, therapeutic implications and future scientific objectives are outlined.

Searching for host immune-microbiome mechanisms in obsessive-compulsive disorder: A narrative literature review and future directions

Obsessive-compulsive disorder (OCD) is disabling and often treatment-refractory. Host immunity and gut microbiota have bidirectional communication with each other and with the brain. Perturbations to this axis have been implicated in neuropsychiatric disorders, but immune-microbiome signaling in OCD is relatively underexplored. We review support for further pursuing such investigations in OCD, including: 1) gut microbiota has been associated with OCD, but causal pathogenic mechanisms remain unclear; 2) early environmental risk factors for OCD overlap with critical periods of immune-microbiome development; 3) OCD is associated with increased risk of immune-mediated disorders and changes in immune parameters, which are separately associated with the microbiome; and 4) gut microbiome manipulations in animal models are associated with changes in immunity and some obsessive-compulsive symptoms. Theoretical pathogenic mechanisms could include microbiota programming of cytokine production, promotion of expansion and trafficking of peripheral immune cells to the CNS, and regulation of microglial function. Immune-microbiome signaling in OCD requires further exploration, and may offer novel insights into pathogenic mechanisms and potential treatment targets for this disabling disorder.