Gut IgA Research Articles

Migratory CD103+CD11b+ cDC2s in Peyer’s patches are critical for gut IgA responses following oral immunization

Induction and regulation of specific intestinal IgA responses critically depend on dendritic cell subsets and the T cells they activate in the Peyer’s patches (PP). We found that oral immunization with cholera toxin (CT) as an adjuvant resulted in migration-dependent changes in the composition and localization of PP DC subsets with increased numbers of CD103- cDC2s and LysoDCs in the subepithelial dome and of CD103+ cDC2s that expressed CD101 in the T cell zones (TZ), while oral OVA tolerization was instead associated with larger quantities of TZ cDC1s and pTregs. Decreased IgA responses were observed after CT adjuvanted immunization in huCD207DTA mice lacking CD103+ cDC2s, while oral OVA tolerization was inefficient in cDC1-deficient Batf3-/- mice. Using Ovalbumin (OVA) TCR transgenic CD4 T cell adoptive transfer models, we found that co-transferred endogenous WT CD4 T cells can hinder the induction of OVA-specific IgA responses through secretion of IL-10. CT could overcome this blocking effect, apparently through a modulating effect on peripherally induced Tregs (pTreg) while promoting an expansion of follicular helper T cells (Tfh). The data support a model where cDC1-induced pTreg normally supress PP responses for any given antigen and where CT’s oral adjuvanticity effect is dependent on promoting Tfh responses through induction of CD103+ cDC2s.

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

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

MZB1-mediated IgA secretion suppresses the development and progression of colorectal cancer triggered by gut inflammation

Colorectal cancer (CRC) ranks among the top causes of mortality globally. Gut inflammation is one crucial risk factor that augments CRC development since patients suffering from inflammatory bowel disease have an increased incidence of CRC. The role of immunoglobulin (Ig)A in maintaining gut homeostasis and preventing inflammation has been well established. Our earlier work demonstrated that the marginal zone and B1 cell-specific protein (MZB1) promotes gut IgA secretion and its absence results in pronounced dextran sulfate sodium salt (DSS)-induced colitis. In the present study, we explored the role of MZB1 in CRC development using the azoxymethane (AOM)/DSS-induced CRC model. We observed an increase in both the number and size of the tumor nodules in Mzb1-/- mice compared with Mzb1+/+ mice. The increase in CRC development and progression in Mzb1-/- mice was associated with reduced intestinal IgA levels, altered gut flora, and more severe gut and systemic inflammation. Oral administration of the monoclonal IgA, W27, alleviated both the gut inflammation and AOM/DSS-induced CRC. Notably, cohousing Mzb1+/+ and Mzb1-/- mice from the 10th day after birth led to similar CRC development. Our findings underscore the pivotal role of MZB1-mediated IgA secretion in suppressing the onset and progression of CRC triggered by gut inflammation. Moreover, our study highlights the profound impact of microbiota composition, modulated by gut IgA levels, on gut inflammation. Nonetheless, establishing a direct correlation between the severity of colitis and subsequent CRC development and the presence or absence of a particular microbiota is challenging.

The expression of immune related genes and potential regulatory mechanisms in schizophrenia

ObjectiveThis study aimed to investigate the role of immune dysfunction in the pathogenesis of schizophrenia through single-cell transcriptome and bulk RNA data analyses. MethodsThe single-cell RNA sequencing (scRNA-seq) was selected to assess the cellular composition and gene expression profiles of the brain tissue. Further, bulk RNA sequencing data was utilized to corroborate findings from the single-cell analyses and provide additional insights into the molecular changes associated with the disease. Gene-drug interaction data was also included to identify potential therapeutic drugs targeting these dysregulated immune-related genes in schizophrenia. ResultsWe discovered significant differences in cellular composition within schizophrenia tissue, including increased infiltration of fibroblasts, horizontal basal cells, monocytes, mesenchymal cells, and smooth muscle cells. The investigation of immune-related genes revealed significantly different expression of genes such as S100A2, CCL14, IGHA1, BPIFA1, GDF15, IL32, BPIFB2, HLA-DRA, S100A8, PTX3, TPM2, TNFRSF12A, GREM1 and others. These genes possibly contribute to the progression of schizophrenia through various pathways such as humoral immune response, IL-17 signaling pathway, adaptive immune response, antigen processing and presentation, and gut IgA production. Our findings also suggest possible transcriptional regulation in schizophrenia's immune dysfunction by transcription factors in monocytes, neutrophils, endothelial cells, and epithelial cells. Lastly, potential therapeutic drugs were identified through gene-drug interaction data, such as those targeting HLA-A and HLAB. ConclusionThe cellular heterogeneity and immune-related gene dysregulation play important roles in schizophrenia, which provides a foundation for understanding the pathogenesis and developing new treatment methods.

Effects of Dietary Microcapsule Sustained-Release Sodium Butyrate on the Growth Performance, Immunity, and Gut Microbiota of Yellow Broilers

The beneficial effects of butyric acid in poultry production are well documented, while the relationship between sodium butyrate (SB) and microcapsule sustained-release sodium butyrate (MSSB), especially in yellow broilers, remains poorly investigated. This study was designed to elucidate the function as well as the potential mechanisms of SB and MSSB in enhancing health in yellow broilers. In total, 360 one-day-old yellow broilers were allocated to three treatment groups. The control group (CON) received a basic diet, while the SB group was provided with 1000 mg/kg of sodium butyrate (SB), and the MSSB received microcapsule sustained-release sodium butyrate (MSSB), all over a period of 56 days. Compared to the CON group, the dietary supplementation of both SB and MSSB showed a lower feed:gain ratio (p < 0.01). No significant (p > 0.05) difference in antioxidant capacity was observed between the three groups. We observed significantly higher levels (p < 0.05) of immunoglobulins and a reduction in concentrations in both the SB and MSSB groups compared to the CON group. Furthermore, both SB and MSSB induced alterations in the diversity, structure, and function of gut microbiota. MSSB demonstrated even more pronounced beneficial effects than SB, particularly in regard to the serum IgA level (p = 0.05), cecal isovalerate concentration (p < 0.05), and villus height (p < 0.01). The sequencing of the gut microbiota revealed that MSSB led to a significant increase in the relative abundance of Clostridia UCG-014, Bacilli RF39, and Oscillospiraceae UCG-005. Predictions of bacterial function indicated changes in KEGG pathways, including an enrichment of tryptophan metabolism (ko00380), and a reduction in fructose and mannose metabolism (ko00051), chloroalkane and chloroalkene degradation (ko00625), and naphthalene degradation (ko00626) in yellow broilers fed with MSSB. Among these, the mediation analysis revealed a causal effect between the Clostridia UCG-014 in the gut and serum IgA, with tryptophan metabolism being a key mediator in this relationship. Our results suggest that dietary MSSB can improve the growth performance, immunity, and gut microbiota of yellow broilers. MSSB increased the abundance of Clostridia UCG-014 and activated the tryptophan metabolism pathway (ko00380), contributing to IgA levels in yellow broilers through this mechanism.

Gut IgA: Never fear, the super inducers are here.

In this issue of Cell Host & Microbe, Zhang etal. show that long-term oral administration of a pectin-derived prebiotic broadly enhanced IgA responses to commensals in the small intestine. This effect required Tcells and involved Lachnospiraceae A2, suggesting that a few symbionts promote IgA responses to many commensals.

Causal effects between gut microbiota and IgA nephropathy: a bidirectional Mendelian randomization study.

Therapeutic approaches that target the gut microbiota (GM) may be helpful in the potential prevention and treatment of IgA nephropathy (IgAN). Meanwhile, relevant studies demonstrated a correlation between GM and IgAN, however, these confounding evidence cannot prove a causal relationship between GM and IgAN. Based on the data from the GM genome-wide association study (GWAS) of MiBioGen and the IgAN GWAS data from the FinnGen research. A bi-directional Mendelian randomization (MR) study was performed to explore the causal relationship between GM and IgAN. We used inverse variance weighted (IVW) method as the primary method to determine the causal relationship between exposure and outcome in our MR study. Besides, we used additional analysis (MR-Egger, weighted median) and sensitivity analysis (Cochrane's Q test, MR-Egger and MR-PRESSO) to select significant results, followed by Bayesian model averaging (MR-BMA) to test the results of MR study. Finally, a reverse MR analysis was conducted to estimate the probability of reverse causality. At the locus-wide significance level, the results of IVW method and additional analysis showed that Genus Enterorhabdus was a protective factor for IgAN [OR: 0.456, 95% CI: 0.238-0.875, p=0.023], while Genus butyricicoccus was a risk factor for IgAN [OR: 3.471, 95% CI: 1.671-7.209, p=0.0008]. In the sensitivity analysis, no significant pleiotropy or heterogeneity of the results was found. Our study revealed the causal relationship between GM and IgAN, and expanded the variety of bacterial taxa causally related to IgAN. These bacterial taxa could become novel biomarkers to facilitate the development of targeted therapies for IgAN, developing our understanding of the "gut-kidney axis".

Microenvironment regulates antibody secretion by IgA+ plasma cells.

Abstract IgA secreting plasma cells (PCs) provide a critical supply of antibodies for barrier functions against pathogens. These cells express unique tissue-driven transcriptional profiles in their respective niches in the bone marrow (BM) and gut. We previously demonstrated that both tissues sustain long-lived IgA+ PCs, but the cell intrinsic and extrinsic signals responsible for survival and function in the gut remain largely unknown. Understanding how the microenvironment regulates tissue resident IgA+ PC functions has implications for maintaining intestinal homeostasis and protection from disease. We found that BM IgA+ PCs functionally differ from gut IgA+ PCs as they secrete significantly more antibody. To assess if this phenotype could be due to metabolic consequences, we profiled IgA+ PCs in both tissues. BM and gut IgA+ PCs have similar glucose and fatty acid uptake. However, BM IgA+ PCs have increased mitochondrial dependence, while gut IgA+ PCs have increased glycolytic capacity. We next altered the composition of the microbiome to determine the role of gut microbes in regulating tissue resident PCs. Our initial experiments used C57BL/6J mice with a well-defined low-complexity microbiome (from Jackson Labs). Co-housing Jax mice with animals containing a more diverse set of microbes led to an increase in antibody secretion. Herein, we identified that the tissue microenvironment and gut microbiome influences PC function. We aim to dissect the mechanisms involved in microbiome driven changes in PC phenotype. Ultimately, understanding how the microenvironment regulates intensity of PC antibody secretion provides a tool in targeting induction of systemic and mucosal responses and will improve vaccine design and development. Supported by grants from NIH (R35 GM147560, R03 AI156481)

Dynamics of the gut microbiome, IgA response, and plasma metabolome in the development of pediatric celiac disease

BackgroundCeliac disease (CD) is an autoimmune disorder triggered by gluten consumption. Almost all CD patients possess human leukocyte antigen (HLA) DQ2/DQ8 haplotypes; however, only a small subset of individuals carrying these alleles develop CD, indicating the role of environmental factors in CD pathogenesis. The main objective of this study was to determine the contributory role of gut microbiota and microbial metabolites in CD onset. To this end, we obtained fecal samples from a prospective cohort study (ABIS) at ages 2.5 and 5 years. Samples were collected from children who developed CD after the final sample collection (CD progressors) and healthy children matched by age, HLA genotype, breastfeeding duration, and gluten-exposure time (n=15–16). We first used 16S sequencing and immunoglobulin-A sequencing (IgA-seq) using fecal samples obtained from the same children (i) 16 controls and 15 CD progressors at age 2.5 and (ii) 13 controls and 9 CD progressors at age 5. We completed the cytokine profiling, and plasma metabolomics using plasma samples obtained at age 5 (n=7–9). We also determined the effects of one microbiota-derived metabolite, taurodeoxycholic acid (TDCA), on the small intestines and immune cell composition in vivo.ResultsCD progressors have a distinct gut microbiota composition, an increased IgA response, and unique IgA targets compared to healthy subjects. Notably, 26 plasma metabolites, five cytokines, and one chemokine were significantly altered in CD progressors at age 5. Among 26 metabolites, we identified a 2-fold increase in TDCA. TDCA treatment alone caused villous atrophy, increased CD4+ T cells, Natural Killer cells, and two important immunoregulatory proteins, Qa-1 and NKG2D expression on T cells while decreasing T-regulatory cells in intraepithelial lymphocytes (IELs) in C57BL/6J mice.ConclusionsPediatric CD progressors have a distinct gut microbiota composition, plasma metabolome, and cytokine profile before diagnosis. Furthermore, CD progressors have more IgA-coated bacteria and unique targets of IgA in their gut microbiota. TDCA feeding alone stimulates an inflammatory immune response in the small intestines of C57BJ/6 mice and causes villous atrophy, the hallmark of CD. Thus, a microbiota-derived metabolite, TDCA, enriched in CD progressors’ plasma, has the potential to drive inflammation in the small intestines and enhance CD pathogenesis.8KKUiKqzQG1iyio8Fngon2Video

A self-sustaining layer of early-life-origin B cells drives steady-state IgA responses in the adult gut.

The adult immune system consists of cells that emerged at various times during ontogeny. We aimed to define the relationship between developmental origin and composition of the adult B cell pool during unperturbed hematopoiesis. Lineage tracing stratified murine adult B cells based on the timing of output, revealing that a substantial portion originated within a restricted neonatal window. In addition to B-1a cells, early-life time-stamped B cells included clonally interrelated IgA plasma cells in the gut and bone marrow. These were actively maintained by B cell memory within gut chronic germinal centers and contained commensal microbiota reactivity. Neonatal rotavirus infection recruited recurrent IgA clones that were distinct from those arising by infection with the same antigen in adults. Finally, gut IgA plasma cells arose from the same hematopoietic progenitors as B-1a cells during ontogeny. Thus, a complex layer of neonatally imprinted B cells confer unique antibody responses later in life.

Probiotics ameliorate IgA nephropathy by improving gut dysbiosis and blunting NLRP3 signaling

BackgroundRecently, a few studies have indicated a relationship between the gut microbiota and IgA nephropathy (IgAN). Whether the gut microbiota participates in the pathogenesis of IgAN and whether probiotics are effective in treating IgAN are still controversial. Therefore, this study aimed to identify the differences in the structure of the gut microbiota between IgAN and controls and to evaluate the efficacy and mechanism of probiotics in the treatment of IgAN.MethodsTo address this question, 35 IgAN patients and 25 healthy volunteers were enrolled, and a mouse IgAN model was also constructed. The stool microbes were analyzed by 16S rRNA high-throughput sequencing to identify the differential strains between IgAN and healthy controls. The impact of probiotics on the structure of the intestinal flora and the efficacy of the probiotics in the treatment of IgAN were evaluated.ResultsAlthough the microflora structure of mice and humans was not the same, both patients and mice with IgAN exhibited gut microbiota dysbiosis, with all subjects presenting an evident decrease in Bifidobacterium levels. The Bifidobacterium proportion was negatively correlated with proteinuria and hematuria levels, indicating that the decreased Bifidobacterium abundance could be related to IgAN severity. Probiotic treatment containing Bifidobacterium in IgAN mice could significantly alleviate gut dysbiosis, specifically by increasing the proportion of beneficial bacteria and reducing the abundance of potentially pathogenic bacteria. Moreover, both probiotics and their metabolites, short-chain fatty acids (SCFAs), could attenuate IgAN clinicopathological manifestations by inhibiting the NLRP3/ASC/Caspase 1 signaling pathway.ConclusionsSupplementation with probiotics mainly containing Bifidobacterium could markedly improve gut dysbiosis in IgAN. Moreover, both probiotics and their SCFA metabolites could attenuate the clinicopathological manifestations of IgAN by inhibiting the NLRP3/ASC/Caspase 1 signaling pathway. Therefore, probiotics have potential as an adjunctive therapy for IgAN.

Altered Immunoglobulin Repertoire and Decreased IgA Somatic Hypermutation in the Gut during Chronic HIV-1 Infection.

ABSTRACTHumoral immune perturbations contribute to pathogenic outcomes in persons with HIV-1 infection (PWH). Gut barrier dysfunction in PWH is associated with microbial translocation and alterations in microbial communities (dysbiosis), and IgA, the most abundant immunoglobulin (Ig) isotype in the gut, is involved in gut homeostasis by interacting with the microbiome. We determined the impact of HIV-1 infection on the antibody repertoire in the gastrointestinal tract by comparing Ig gene utilization and somatic hypermutation (SHM) in colon biopsies from PWH (n = 19) versus age and sex-matched controls (n = 13). We correlated these Ig parameters with clinical, immunological, microbiome and virological data. Gene signatures of enhanced B cell activation were accompanied by skewed frequencies of multiple Ig Variable genes in PWH. PWH showed decreased frequencies of SHM in IgA and possibly IgG, with a substantial loss of highly mutated IgA sequences. The decline in IgA SHM in PWH correlated with gut CD4+ T cell loss and inversely correlated with mucosal inflammation and microbial translocation. Diminished gut IgA SHM in PWH was driven by transversion mutations at A or T deoxynucleotides, suggesting a defect not at the AID/APOBEC3 deamination step but at later stages of IgA SHM. These results expand our understanding of humoral immune perturbations in PWH that could have important implications in understanding mucosal immune defects in individuals with chronic HIV-1 infection.IMPORTANCE The gut is a major site of early HIV-1 replication and pathogenesis. Extensive CD4+ T cell depletion in this compartment results in a compromised epithelial barrier that facilitates the translocation of microbes into the underlying lamina propria and systemic circulation, resulting in chronic immune activation. To date, the consequences of microbial translocation on the mucosal humoral immune response (or vice versa) remains poorly integrated into the panoply of mucosal immune defects in PWH. We utilized next-generation sequencing approaches to profile the Ab repertoire and ascertain frequencies of somatic hypermutation in colon biopsies from antiretroviral therapy-naive PWH versus controls. Our findings identify perturbations in the Ab repertoire of PWH that could contribute to development or maintenance of dysbiosis. Moreover, IgA mutations significantly decreased in PWH and this was associated with adverse clinical outcomes. These data may provide insight into the mechanisms underlying impaired Ab-dependent gut homeostasis during chronic HIV-1 infection.

Ontogeny of the B Cell Receptor Repertoire and Microbiome in Mice

The immune system matures throughout childhood to achieve full functionality in protecting our bodies against threats. The immune system has a strong reciprocal symbiosis with the host bacterial population and the two systems co-develop, shaping each other. Despite their fundamental role in health physiology, the ontogeny of these systems is poorly characterized. In this study, we investigated the development of the BCR repertoire by analyzing high-throughput sequencing of their receptors in several time points of young C57BL/6J mice. In parallel, we explored the development of the gut microbiome. We discovered that the gut IgA repertoires change from birth to adolescence, including an increase in CDR3 lengths and somatic hypermutation levels. This contrasts with the spleen IgM repertoires that remain stable and distinct from the IgA repertoires in the gut. We also discovered that large clones that germinate in the gut are initially confined to a specific gut compartment, then expand to nearby compartments and later on expand also to the spleen and remain there. Finally, we explored the associations between diversity indices of the B cell repertoires and the microbiome, as well as associations between bacterial and BCR clusters. Our results shed light on the ontogeny of the adaptive immune system and the microbiome, providing a baseline for future research.

MICRORNA-10A NEGATIVELY REGULATES INTESTINAL IGA RESPONSE THROUGH SUPPRESSING REGULATORY T CELLS CONVERSION TO T FOLLICULAR REGULATOR CELLS

Abstract Intestinal IgA response is a key immune regulation between host and gut microbiota. Regulatory T cells (Tregs) have been recently shown to promote IgA responses through conversion to T follicular regulator cells (TFRs). However, how Treg converts to TFR to promote intestinal IgA response remain unclear. Tregs express microRNA (miR)-10a at high levels, however, whether it regulates TFR generation and function is unknown. We found that Treg cell-specific miR-10a deficient Foxp3YFP-cre miR-10af/f (Foxp3ΔmiR-10a) mice displayed higher levels of gut IgA compared to wild type (WT) Foxp3YFP-cre miR-10af/+ mice. TFRs in Peyer’s patches were also significantly increased while there were no differences in germinal center B cells, Tregs, and TFH cells. When orally immunized with cholera toxin (CT), Foxp3ΔmiR-10a mice showed more CT-specific fecal IgA and TFRs. miR-10a deficient Tregs induced more IgA compared to WT Tregs when co-cultured with naïve B cells in vitro. When transferred to TCRβxδ−/− mice, miR-10a deficient Tregs induced more gut IgA and higher levels of TFRs compared to WT Tregs in vivo. However, gut microbiota composition in Foxp3ΔmiR-10a mice was not altered by 16S rRNA gene sequencing. RNA-sequencing analysis showed that miR-10a was enriched in the oxidative phosphorylation (OXPHOS) process in Tregs. Consistently, miR-10a deficient Tregs displayed higher OXPHOS metabolic levels by seahorse analysis. Pretreatment of Tregs with oligomycin, which inhibits OXPHOS, inhibited Treg induction of IgA production in vitro, indicating miR-10a suppressed Tregs induction of IgA ability by inhibiting OXPHOS. Thus, miR-10a negatively regulates TFRs conversion through inhibition of OXPHOS to control intestinal IgA response.

The development of a gut-specific immune response to an oral antigen is dependent on α4β7 mediated lymphocyte trafficking

Abstract Objective Vedolizumab has been shown to reduce the antibody response to an oral cholera, but not intramuscular hepatitis B vaccine in healthy subjects (Wyant, Gut 2015). The generation of an immune response to an oral antigen (Ag) begins at inductive sites such as Peyer’s patches (PP) followed by cell migration to effector sites in the gut. The integrin α4β7 is known to play a major role in cell trafficking to gut-associated lymphoid tissues. This study assessed whether MT-102, a potent and selective small molecule α4β7 inhibitor has similar effects on immunizations to those reported in the clinic for vedolizumab. Methods An in vivo immunization model system was established to determine the effects of MT-102, dosed via osmotic minipump, on the development of a gut-specific immune response. Mice were orally immunized with cholera toxin (CTX), and anti-CTX antibodies were quantified in fecal and plasma samples. The impact of MT-102 on lymphocytes within the PP of immunized mice was determined by flow cytometry. Results MT-102 delayed the production of anti-CTX IgA and IgG antibodies as measured in fecal samples without perturbing total gut IgA levels. Furthermore, MT-102 also inhibited the levels of Ag-specific antibodies in the plasma following repeated CTX oral immunizations. Blocking α4β7 induced a decrease in the frequency of B cells in the PP of treated mice compared to the control group. Conclusion α4β7-specific inhibitor, MT-102, effectively diminished the mucosal antibody response to an orally delivered Ag in mice. These results are consistent with what has been reported clinically in vedolizumab-treated subjects and thus establishes that potent small molecule inhibitors of α4β7 can replicate the pharmacology of an antibody.

Microbiota, IgA and Multiple Sclerosis.

Multiple sclerosis (MS) is a neuroinflammatory disease characterized by immune cell infiltration in the central nervous system and destruction of myelin sheaths. Alterations of gut bacteria abundances are present in MS patients. In mouse models of neuroinflammation, depletion of microbiota results in amelioration of symptoms, and gavage with MS patient microbiota exacerbates the disease and inflammation via Th17 cells. On the other hand, depletion of B cells using anti-CD20 is an efficient therapy in MS, and growing evidence shows an important deleterious role of B cells in MS pathology. However, the failure of TACI-Ig treatment in MS highlighted the potential regulatory role of plasma cells. The mechanism was recently demonstrated involving IgA+ plasma cells, specific for gut microbiota and producing IL-10. IgA-coated bacteria in MS patient gut exhibit also modifications. We will focus our review on IgA interactions with gut microbiota and IgA+ B cells in MS. These recent data emphasize new pathways of neuroinflammation regulation in MS.

Effect of dietary supplementation of Tryptophan, Arginine, and Glutamine on growth performance, gut morphology, immune response and meat quality of broiler chicken

Two experiments were conducted to evaluate the supplemental effects of Arginine (Arg), Glutamine (Gln) and Tryptophan (Trp) on growth performance, gut morphology, immune response and meat quality of broilers. In experiment 1, 312 one-day-old Ross×Ross broiler chicks with similar body weight were randomly assigned to 4 dietary treatments (C, control having no amino acids; Arg, a diet with 0.5% L-Arg; Gln, a diet with 0.5% L-Gln and Trp, a diet with 0.5% L-Trp), each containing 6 replicate cages with 13 birds per cage. For further confirmation, experiment 2 considered similar treatments as of experiment 1. Body weight and feed intake were measured weekly. At 2ndand 6thweeks of age, 12 birds per treatment were killed in both experiments to measure gut morphology, serum IgG and IgA and meat quality of broilers. In Expt 1, results showed that dietary Arg, Gln and Trpsupplementation significantly increased (P< 0.05) weight gain and feed intake of broilers than those of control group. In experiment 2, a similar performance trend was obtained compared to Experiment 1. Circulating levels of IgG and IgA were increased with supplementation of AAs in the diet. In both experiments, the breastand drumstick muscles of the group of birds feed amino acids had a higher pH and redness (a*) values, but lower lightness (L*) and yellowness (b*) values of meat. Chicks fed diet with Arg, Gln and Trp had longer villi height and villi to crypt depth ratio, and shorter crypt depth as compared with the control (P<0.05). Thus the addition of Arg, Trp and Gln each at 0.5% in the diet of broiler chicken enhanced growth performance, immunity, gut morphology and meat quality characteristics of broiler.

Effect of Impaired T Cell Receptor Signaling on the Gut Microbiota in a Mouse Model of Systemic Autoimmunity.

T cell receptor (TCR) signaling abnormalities and gut dysbiosis are thought to be involved in the development of systemic lupus erythematosus (SLE). However, it is not known whether these mechanisms are interrelated. This study was undertaken to explore the impact of defective TCR signaling on microbiota-driven immune responses and the consequent triggering of systemic autoimmunity. The responses of B6SKG mice harboring a mutation in ZAP-70 leading to spontaneous development of SLE were evaluated under specific pathogen-free (SPF) and germ-free (GF) conditions. The gut microbiome was analyzed using 16S ribosomal RNA sequencing. Secretory IgA production in the gut and follicular helper T (Tfh) cell development in the spleen and Peyer's patches were analyzed. Interleukin-17 (IL-17)-deficient mice and segmented filamentous bacteria (SFB)-specific TCR-transgenic mice were used to examine the role of IL-17 and thymic selection. SLE development in B6SKG mice was significantly more attenuated under GF conditions than under SPF conditions. The gut microbiota in B6SKG mice was altered, which was associated with the expansion of SFB and consequent development of SLE by driving Th17 cell differentiation, which was in turn blunted by IL-17 deficiency. Notably, although systemic Tfh development and autoantibody IgG response were enhanced, local gut Tfh and IgA responses were impaired. Moreover, experiments in SFB-specific TCR-transgenic mice revealed that this differential response was caused by altered thymic selection of self- and microbiota-reactive TCR because of defective TCR signaling. Our findings indicate that defective TCR signaling alters the gut microbiota and promotes systemic autoimmunity by driving Th17 cell differentiation.

Effects of production system on the gut microbiota diversity and IgA distribution of Kampong chickens, Indonesia

Abstract. Susanti R, Christijanti W. 2022. Effects of production system on the gut microbiota diversity and IgA distribution of Kampong chickens. Biodiversitas 23: 1082-1090. Native chickens (Kampong chickens) are poultry in Indonesia that is raised using a traditional production system. This study aimed to analyze the differences of the Kampong chicken production system (extensive/E and semi-intensive/SI) on the diversity and abundance of gut microbiota and the distribution of IgA. Each sample of Kampong chickens was slaughtered, then their thoracic and abdominal cavities were dissected, and their intestines were collected. Furthermore, the intestinal tissue was processed to make histological preparations for immunohistochemical analysis of IgA. Gut contents of 25 g were taken aseptically and used for next-generation sequencing (NGS) and GC-MS analysis. The results showed 12 bacterial phyla in the intestines of SI and E chicken. E chickens had a higher abundance and diversity of microbiota than the SI chickens. The phylum Firmicutes dominated the E and SI chickens' gut microbiota (>50%). SI chickens have a higher Firmicutes/Bacteroidetes ratio than the E chickens. The SIgA distribution showed an IRS score of 4 (moderate), both in E and SI chickens. It was concluded that the production system affects the intestinal microbiota's abundance and diversity but not on the intestine IgA of Kampong Chickens. This study highlights that based on the Firmicutes/Bacteroidetes ratio, the semi-intensive system is more suitable for Kampong chicken meat and eggs than the extensive system.

Construction of the Enterococcal Strain Expressing Immunogenic Fragment of SARS-Cov-2 Virus

Contemporary SARS-Cov-2 pandemic, besides its dramatic global influence on the human race including health care systems, economies, and political decisions, opened a window for the global experiment with human vaccination employing novel injectable vaccines providing predominantly specific IgG response with little knowledge of their impact on the mucosal immunity. However, it is widely accepted that protection against the pathogens at the gates of the infection - on mucosal surfaces—predominantly rely on an IgA response. Some genetically modified bacteria, including probiotics, represent attractive vehicles for oral or nasal mucosal delivery of therapeutic molecules. Probiotic-based vaccines for mucous membranes are easy to produce in large quantities; they have low cost, provide quite a long T-cell memory, and gut IgA response to oral vaccines is highly synchronized and strongly oligoclonal. Here we present a study demonstrating construction of the novel SARS-Cov-2 vaccine candidate employing the gene fragment of S1 SARS-Cov-2 gene. This DNA fragment was inserted in frame into major pili protein gene with d2 domain of enterococcal operon encoding for pili. The DNA sequencing proved the presence of the insert in enterococcal genome. RNA transcription, immunoprecipitation, and immune electron microscopy with human sera obtained from the SARS-Cov-2 patients demonstrated expression of SARS-Cov-2 antigens in bacteria. Taken together the data obtained allowed considering this genetically modified probiotic strain as an interesting candidate for vaccine against SARS-Cov-2.