Role In Mucosal Immunity Research Articles

Antimicrobial activity of human α-defensin 5 and its linear analogs: N-terminal fatty acylation results in enhanced antimicrobial activity of the linear analogs

Human α-defensin 5 (HD5) exhibits broad spectrum antimicrobial activity and plays an important role in mucosal immunity of the small intestine. Although there have been several studies, the structural requirements for activity and mechanism of bacterial killing is yet to be established unequivocally. In this study, we have investigated the antimicrobial activity of HD5 and linear analogs. Cysteine deletions attenuated the antibacterial activity considerably. Candidacidal activity was affected to a lesser extent. Fatty acid conjugated linear analogs showed antimicrobial activity comparable activity to HD5. Effective surface charge neutralization of bacteria was observed for HD5 as compared to the non-fatty acylated linear analogs. Our results show that HD5 and non-fatty acylated linear analogs enter the bacterial cytoplasm without causing damage to the bacterial inner membrane. Although fatty acylated peptides exhibited antimicrobial activity comparable to HD5, their mechanism of action involved permeabilization of the Escherichia coli inner membrane. HD5 and analogs had the ability to bind plasmid DNA. HD5 had greater binding affinity to plasmid DNA as compared to the analogs. The three dimensional structure of HD5 favors greater interaction with the bacterial cell surface and also with DNA. Antibacterial activity of HD5 involves entry into bacterial cytoplasm and binding to DNA which would result in shut down of the bacterial metabolism leading to cell death. We show how a moderately active linear peptide derived from the α-defensin HD5 can be engineered to enhance antimicrobial activity almost comparable to the native peptide.

Mesenteric Lymphatic-Perilymphatic Adipose Crosstalk: Role in Alcohol-Induced Perilymphatic Adipose Tissue Inflammation

The digestive tract lymphatics transport approximately two-thirds of all lymph produced in the body and have a key role in mucosal immunity through their contribution to antigen transport and immune cell trafficking. Mesenteric lymphatic pumping function integrity is critical for maintaining homeostasis and lipid transport. We previously demonstrated that acute alcohol intoxication (AAI) increases mesenteric lymphatic amplitude of contraction and ejection fraction, enhancing the ability of the lymphatic vessels to pump lymph. AAI has been shown to disrupt intestinal barrier integrity, which would be expected to increase the endotoxin content of mesenteric lymph. In this study, we tested the prediction that AAI increases lymphatic permeability directly affecting perilymphatic adipose tissue (PLAT) milieu. Male Sprague Dawley rats received an intragastric infusion of 2.5g/kg of alcohol. Isovolumic administration of water (vehicle) served as control. PLAT was isolated for the determination of Evans Blue extravasation (permeability), cytokine content, and immunohistochemistry for inflammatory cell infiltration at 30minutes and 24hours after alcohol administration. PLAT isolated from AAI animals had greater Evans Blue concentrations and cytokine expression (24hours post-AAI) and mast cell and neutrophil density than that isolated from controls. AAI resulted in significantly higher plasma lipopolysaccharide (endotoxin) levels, lower plasma adiponectin levels (at 30minutes), and unchanged plasma visfatin levels. The data indicate that AAI induces mesenteric lymphatic hyperpermeability, promotes PLAT inflammatory milieu and disrupts the systemic adipokine profile. These findings suggest an association between alcohol-induced lymphatic hyperpermeability and early manifestations of metabolic dysfunction as a result of alcohol abuse. We propose that crosstalk between lymph and PLAT results in adipose inflammation and adipokine dysregulation during AAI.

Primary and Chronic HIV Infection Differently Modulates Mucosal Vδ1 and Vδ2 T-Cells Differentiation Profile and Effector Functions.

Gut-associated immune system has been identified as a major battlefield during the early phases of HIV infection. γδ T-cells, deeply affected in number and function after HIV infection, are able to act as a first line of defence against invading pathogens by producing antiviral soluble factors and by killing infected cells. Despite the relevant role in mucosal immunity, few data are available on gut-associated γδ T-cells during HIV infection. Aim of this work was to evaluate how primary (P-HIV) and chronic (C-HIV) HIV infection affects differentiation profile and functionality of circulating and gut-associated Vδ1 and Vδ2 T-cells. In particular, circulating and mucosal cells were isolated from respectively whole blood and residual gut samples from HIV-infected subjects with primary and chronic infection and from healthy donors (HD). Differentiation profile and functionality were analyzed by multiparametric flow cytometry. P-HIV and C-HIV were characterized by an increase in the frequency of effector Vδ1-T cells both in circulating and mucosal compartments. Moreover, during P-HIV mucosal Vδ1 T-cells expressed high levels of CD107a, suggesting a good effector cytotoxic capability of these cells in the early phase of infection that was lost in C-HIV. P-HIV induced an increase in circulating effector Vδ2 T-cells in comparison to C-HIV and HD. Notably, P-HIV as well as HD were characterized by the ability of mucosal Vδ2 T-cells to spontaneously produce IFN-γ that was lost in C-HIV. Altogether, our data showed for the first time a functional capability of mucosal Vδ1 and Vδ2 T-cells during P-HIV that was lost in C-HIV, suggesting exhaustion mechanisms induced by persistent stimulation.

IL-15 temporally reorients IL-10 biased B-1a cells toward IL-12 expression.

Interleukin (IL)-15 is known to strongly modulate T-cell function; however, its role in controlling mucosal immunity, including its ability to modulate B-1a cell activity, remains to be elucidated. Here, we show that IL-15 upregulates activation molecules and the costimulatory molecule CD80 on viable B-1a cells. Cell activation was accompanied by the depletion of sialic acid-binding immunoglobulin-like lectin (Siglec)-G, an inhibitor of cell activation that is present on B-1a cells. The IL-15 receptor CD122 was stimulated on B-1a cells by the cytokine showing its direct involvement in IL-15-mediated responses. IL-10 is responsible for the long term survival of B-1a cells in culture, which is initially promoted by IL-15. The upregulation of IL-10 was followed by the appearance of suppressor of cytokine signaling (SOCS)1 in the presence of IL-15 and the loss of IL-10. This resulted in the cells switching to IL-12 expression. This anti-inflammatory to pro-inflammatory shift in the B-1a cell character was independent of the cell-specific marker CD5, which remained highly expressed throughout the in vitro life of the cells. The presence of the immunosuppressive receptor programmed cell death (PD)-1 and its ligand PD-L2 were features of a predominantly IL-10 response. PD-1 and PD-L2 can mediate juxtacrine signaling. However, the abrogation of PD-1 and its ligand was observed when the cells expressed IL-12. This demonstrates an inverse relationship between the receptor and ligand and the pro-inflammatory cytokine. The induction of IgM and IgA, which can play pivotal roles in mucosal immunity, was promoted in the presence of IL-15. Collectively, the data implicate IL-15 as the master cytokine that induces B-1a cells to mount a mucosal immune response.

DEFA gene variants associated with IgA nephropathy in a Chinese population.

IgA nephropathy (IgAN) is a complex syndrome with high genetic heterogeneity. More recently, a genome-wide association study (GWAS) from Southern Han population revealed that variants within 8p23.1, where the DEFA genes encoding a-defensins assembled, were associated with susceptibility to IgAN. To replicate the association and fine-map the genetic variants, a case-control genetic study from an independent Northern Han cohort was conducted. A total of 60 single-nucleotide polymorphisms in a region spanning 350 kb encompassing the DEFA genes cluster were analyzed in 2096 individuals. Copy number variations of DEFA1A3 within the loci were also checked for the independent association. Functional significance of the associated variants was further examined by the in silico method as well as by cis-acting expression quantitative trait loci analysis with mRNA. It showed that 17 out of 60 (28.3%) variants were associated with susceptibility to IgAN. Two independent signals with functional potentials were discovered (rs2738058, P=4.64 × 10(-5), odds ratio (OR)=0.76, 95% confidence interval (CI) 0.66-0.87 and rs9644778, P=4.78 × 10(-3), OR=1.21, 95% CI 1.06-1.39). Besides, marginally significant association of rs9644778 risk genotype with lower proportion of gross hematuria (CC+CA vs AA 35.2% vs 30.2%, P=0.073) was observed. In conclusion, DEFA gene polymorphisms have potentially pathogenic roles in IgAN, and the role of mucosal immunity in the pathogenesis of IgAN has to be emphasized.

Compartment-specific immunity in the human gut: properties and functions of dendritic cells in the colon versus the ileum

ObjectiveDendritic cells (DC) mediate intestinal immune tolerance. Despite striking differences between the colon and the ileum both in function and bacterial load, few studies distinguish between properties of immune cells...

Measurement of salivary Immunoglobulin A of participants with a healthy, gingivitis and chronic periodontitis conditions

Background: Secretory Immunoglobulin A (SIgA) is a subclass of Immunoglobulin A (IgA), It is an antibody that plays an important role in mucosal immunity. It is the main immunoglobulin found in mucous secretions from mammary glands, tear glands and salivary glands, every pathologic process in the body involves the immune system, and periodontal inflammation is one of them and is not an exception. Material and methods: this study was consisted of 60 healthy male participants of an age ranged between (35-50) years old ; 25 of them with generalized moderate chronic periodontists(Clinical Attachment Loss equal to 3-4mm at ≥ 30% of the sites; 20 participants with plaque induced gingivitis and 15 participants had clinically healthy periodontium as control group. oral examination include Plaque Index, Gingival Index, Probing Pocket Depth and Clinical Attachment Level were conducted for all participants four sites were examined for each tooth (labial ,lingual, mesial and distal), 2ml of unstimulated whole saliva was collected from all participants to measure Secretory Immunoglobulin A in µg /ml by Enzyme-linked immunosorbent assay technique. Results: salivary IgA(sIgA) mean was (356.3) µg /ml for the chronic periodontitis patients; while it was 202 µg /ml for plaque induced gingivitis patients and it was 129.2 µg /ml for the control group. Highly significant differences among the three group were recorded (P-value <0.001). For chronic periodontitis patients, the Plaque Index Gingival Index scores were positively highly significant correlated with Secretory Immunoglobulin A level in saliva. The Probing Pocket Depth scores were positively and significantly associated with Secretory Immunoglobulin A level. The Clinical Attachment Level scores were positively but non significant associated with Secretory Immunoglobulin A level. For the gingivitis and the control group they were positive non significant association between the periodontal parameters and the Secretory Immunoglobulin A level in saliva. Conclusion: there is a correlation between Secretory Immunoglobulin A level in saliva and the periodontal health status.

Selective IgA deficiency associated with allergy to cow's milk protein, case report

Event Abstract Back to Event Selective IgA deficiency associated with allergy to cow's milk protein, case report Catalina M. Gómez Henao1*, Cristina I. Herrera Morales1, Ana M. Celis Henao1 and Carlos F. Chinchilla Mejía1 1 Universidad de Antioquia, Colombia Background: IgA is the most abundant immunoglobulin in the human; it is found in tissues and in secretions especially from the gastrointestinal tract reflecting its role in mucosal immunity and the development of tolerance. Selective IgA deficiency (<10mg/dl) is the most common primary immunodeficiency, most patients with IgA deficiency are asymptomatic so its clinical significance is unknown, although it has been associated with increased incidence of some autoimmune and allergic diseases, being food allergy and asthma most frequently related. The protein allergy to cow's milk is one of the most prevalent and important food allergies in childhood. In patients with allergy to proteins in cow's milk have been shown a decrease in the production of TGF-β, one of the main cytokines that stimulate the production of IgA by B cells, a mechanism that could also be explaining the relationship between allergy to the protein in cow's milk with selective IgA deficiency. Objective: To report a case of protein allergy to cow's milk in the presence of IgA deficiency. Methods: Case Report Results: Patient 5 years of age, female, personal history of recurrent infections, rhinitis and Asthma, with colic pain since three years of age that is increased with cow milk intake, tolerate forms extensively cooked. Treatments: Salmeterol/Fluticasone 25-125 every 12 hours. Montelukast 4 mg daily, 100mg daily Mometasone Furoate. Paraclinical: IgA: 0.4 (20-358), IgG: 999, IgM 132.4, specific IgE for casein 4.5 IU/ml (class 3), Alpha-lactalbumin 2.98 (Class 2) Whole cow's milk 2.82 (Class 2), beta-lactoglobulin 0 (Class 0), dog dander 2.2 (Class 2). Prick test negative, albumin 4.8. Avoidance of cow's milk is recommended. During follow-up the patient gradually decreases levels of specific IgE to cow's milk protein, Tolerating lactose-free formulas to 7 years, with a slight increase in levels of IgA (13.9mg/dl). Conclusion: This case illustrates a clear association between selective IgA deficiency and food allergy which has been previously described in the literature, specifically in our patient allergic to cow's milk protein.

Factors Influencing Reconstitution of Mucosal-Associated Invariant T Cells Following Allogeneic Hematopoietic Stem Cell Transplantation

Background: Mucosal-associated invariant T (MAIT) cells are innate-like T cells characterized by high expression of CD161 and a semi-invariant T cell receptor (TCR) comprised of a Vα7.2-Jα33 alpha chain and a limited Vβ repertoire that enables their activation by riboflavin metabolites produced by distinct bacterial and fungal species. MAIT cells are infrequent in cord blood, but undergo TCR-dependent accumulation in neonates in response to gastrointestinal (GI) commensal colonization to comprise approximately 10% of T cells in adult blood. The GI localization of MAIT cells, their capacity to secrete IL-17, and their activation by microbial metabolites suggests a role in mucosal immunity that may be particularly important after allogeneic hematopoietic stem cell transplantation (HCT) when the GI mucosal barrier is compromised and adaptive immunity is impaired. After HCT, the composition of the GI microbiota may be modified by antibiotics, mucositis and immunosuppression, yet its impact on MAIT cell reconstitution, function and post-transplant immunity remain unknown.Aims: To characterize and identify factors influencing MAIT cell reconstitution and function after HCT.Methods: Blood and stool samples were collected from healthy donors and HCT patients prior to and at distinct times after HCT. Absolute counts of MAIT cells, identified as CD3+/CD161hi/Vα7.2+events, were determined in peripheral blood using flow cytometry performed in conjunction with a complete blood count. The bacterial composition of stool was characterized using bacterial 16S rRNA gene PCR with high throughput sequencing and phylogenetic assignment of the amplified fragments. TCR signaling pathway activation in MAIT cells and conventional T cells was evaluated using flow cytometry analysis of phosphoprotein expression after stimulation through the TCR-CD3 complex with anti-CD3/anti-CD28 monoclonal antibodies. TCR Vβ repertoire assessment was performed using high throughput TCRBV gene sequencing.Results: High throughput TCRBV gene sequencing showed that MAIT cells from different donors (n = 3) shared TCRBV sequences, consistent with their capacity to be activated by common GI microbial TCR ligands. Despite GI microbial colonization, MAIT cells from adult donor blood were quiescent and did not proliferate to TCR stimulation. Phosphoprotein flow cytometry established that phosphorylation of proximal TCR signaling pathway molecules (CD3ζ, Lck, and ZAP-70) was diminished and responsible for impaired TCR signaling in adult MAIT cells compared to conventional αβ T cells. MAIT cell proliferation was restored by TCR stimulation in the presence of IL-1β, IL-12, IL-18 and IL-23, raising the possibility that the post-HCT inflammatory environment might be permissive for MAIT cell proliferation driven by GI microbial TCR ligands. We examined the kinetics of MAIT cell reconstitution in HCT patients (n = 163). MAIT cell numbers were lower in patients before conditioning compared to healthy individuals, and were further depleted on the day of stem cell infusion; however, they proliferated in the post-HCT environment in association with induction of Ki67 expression and reached a plateau after day 30 post-HCT (healthy, 56.8/μL; day 30, 6.7/μL). MAIT cell reconstitution after peripheral blood stem cell (PBSC) transplantation was similar comparing myeloablative (MA) and reduced intensity conditioning (RIC) regimens and related compared to unrelated donors, but was highly variable between individuals. Short tandem repeat PCR chimerism studies showed that MAIT cells were of donor origin early after MA and RIC PBSC transplantation. MAIT cell reconstitution was markedly impaired in recipients of cord blood, which contains few MAIT cells, compared to those receiving PBSC, in which MAIT cells are plentiful, suggesting that early MAIT cell reconstitution is primarily derived from mature cells transferred with the HCT graft. Analysis of stool samples from HCT recipients (n = 17) has shown that the relative abundance of distinct gut bacterial species is highly variable between recipients and changed during the course of HCT. Analyses of the relationship between the microbiota and MAIT cell reconstitution will be presented.Conclusions: MAIT cell recovery following HCT varies between different types of transplants and may be influenced by the transferred graft source, the post-HCT environment, and the gut microbiome. DisclosuresNo relevant conflicts of interest to declare.

Regulatory role of CD40 in obesity-induced insulin resistance

Excessive nutrient intake in obesity triggers the accumulation of various types of immune cells in adipose tissue, particularly visceral adipose tissue (VAT). This can result in chronic inflammation which disrupts insulin effects on adipocytes and muscle cells and culminates in development of insulin resistance. The interplay between immune cells and adipose tissue is a key event for the development of insulin resistance that precedes type 2 diabetes. CD40, a well-documented costimulatory receptor, is required for efficient systemic adaptive immune responses. However, we and other groups recently showed that CD40 unexpectedly ameliorates inflammation in VAT and accordingly attenuates obesity-induced insulin resistance. Specifically, although CD40 is typically considered to play its principal immune roles on B lymphocytes and myeloid cells, we found that CD40+CD8+ T lymphocytes were major contributors to the protective effect. This unexpected inhibitory role of CD40 on CD8+ T cell activation in VAT may reflect unique features of this microenvironment. Additional knowledge gaps include whether CD40 also plays roles in mucosal immunity that control the homeostasis of gut microbiota, and human metabolic diseases. Potential therapeutic approaches, including stimulating CD40 signaling and/or manipulating specific CD40 signaling pathways in the VAT microenvironment, may open new avenues for treatment of obesity-induced insulin resistance, and prevention of type 2 diabetes.

Mucosal-associated invariant T cell deficiency in systemic lupus erythematosus.

Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections and play an important role in mucosal immunity. However, the role of MAIT cells remains enigmatic in autoimmune diseases. In this study, we examined the level and function of MAIT cells in patients with rheumatic diseases. MAIT cell, cytokine, and programmed death-1 (PD-1) levels were measured by flow cytometry. Circulating MAIT cell levels were significantly reduced in systemic lupus erythematosus (SLE) and rheumatoid arthritis patients. In particular, this MAIT cell deficiency was more prominent in CD8(+) and double-negative T cell subsets, and significantly correlated with disease activity, such as SLE disease activity index and 28-joint disease activity score. Interestingly, MAIT cell frequency was significantly correlated with NKT cell frequency in SLE patients. IFN-γ production in MAIT cells was impaired in SLE patients, which was due to an intrinsic defect in the Ca(2+)/calcineurin/NFAT1 signaling pathway. In SLE patients, MAIT cells were poorly activated by α-galactosylceramide-stimulated NKT cells, thereby showing the dysfunction between MAIT cells and NKT cells. Notably, an elevated expression of PD-1 in MAIT cells and NKT cells was associated with SLE. In rheumatoid arthritis patients, MAIT cell levels were significantly higher in synovial fluid than in peripheral blood. Our study primarily demonstrates that MAIT cells are numerically and functionally deficient in SLE. In addition, we report a novel finding that this MAIT cell deficiency is associated with NKT cell deficiency and elevated PD-1 expression. These abnormalities possibly contribute to dysregulated mucosal immunity in SLE.

The phenotype and activation status of T and NK cells in porcine colostrum suggest these are central/effector memory cells

In pigs, the epitheliochorial placenta does not allow transfer of maternally derived antibodies or immune cells to the fetus. Thus, piglets are dependent on intake of colostrum for acquisition of passive immunity during the neonatal period. As well as immunoglobulin G (IgG), cellular components of colostrum, mainly lymphocytes, can enter the systemic circulation and secondary lymphoid organs of the neonate. In order to understand the function and immunological role of these cells, a flow cytometric study was undertaken to characterise the cellular profile and phenotype of T cells and NK cells present in porcine colostrum.The results indicated that the greatest numbers of lymphocytes were found on the first day of lactation. The predominant cell types in colostrum were CD8+ single positive T cells (53.6%), followed by CD4+CD8+ double positive T cells (21.1%), CD2+CD8+ γδ T cells (15.0%) and NK cells (13.5%). CD4+ single positive T cells (4.4%) and other γδ T cell subpopulations (1.8% CD2−CD8− and 0.4% CD2+CD8−) were present in colostrum at low levels. Although the profile of the T cell subpopulations during the first 3 days of lactation remained constant, the absolute numbers of T and NK cells decreased significantly in the first few hours of lactation. Expression of CCR7, CD11b, CD25, CD45RA and MHC class II was used to assess the activation status of T and NK cells in colostrum. T cell subpopulations expressed markers consistent with an effector memory phenotype, indicating that these were antigen-experienced cells. The phenotype of colostral T and NK cells suggests a role in mucosal immunity and potentially in transfer of passive immunity from sow to piglet.

Characteristics of γδ T cells in Schistosoma japonicum-infected mouse mesenteric lymph nodes

Gamma delta (γδ) T cells are mainly present in mucosa-associated lymphoid tissues, which play an important role in mucosal immunity. In this study, C57BL/6 mice were infected by Schistosoma japonicum and lymphocytes were isolated from the mesenteric lymph node (MLN) to identify changes in the phenotype and function of γδ T cells using flow cytometry. Our results indicated that the absolute number of γδ T cells from the MLNs of infected mice was significantly higher compared with normal mice (P < 0.05). In addition, the infected γδ T cells expressed a high level of the activated molecule CD69 (P < 0.01) and demonstrated an increasing population of CD4(+) γδ T cells (P < 0.05). MLN γδ T cells secrete interferon-γ (IFN-γ), interleukin (IL)-4, IL-9, and IL-17 in response to propylene glycol monomethyl acetate (PMA) plus ionomycin simulation, and the levels of IL-4, IL-9, and IL-17 increased significantly after S. japonicum infection (P < 0.05). Taken together, these findings indicated that S. japonicum infection could induce γδ T cell activation, proliferation, and differentiation in the MLN. Moreover, our results indicated that the expression of NKG2D (CD314) was not increased in γδ T cells after infection, suggesting that other mechanisms are involved in activating γδ T cells. Furthermore, higher expression of programmed death-1 (CD279) but not IL-10 was detected in the γδ T cells isolated from infected mice (P < 0.05), suggesting that the function of γδ T cells is inhibited gradually over the course of S. japonicum infection.

Downregulation of chicken interleukin-17 receptor A during Eimeria infection.

Both interleukin-17A (IL-17A) and IL-17F are proinflammatory cytokines that have an important role in intestinal homeostasis via receptor signaling. These cytokines have been characterized in chickens, but very little is known about their receptors and their functional activity. We provide here the first description of the sequence analysis, bioactivity, and comparative expression analysis of chicken IL-17RA (chIL-17RA) in chickens infected with Salmonella and Eimeria, two major infectious agents of gastrointestinal diseases of poultry of economic importance. A full-length chIL-17RA cDNA with a 2,568-bp coding region was identified from chicken thymus cDNA. chIL-17RA shares ca. 46% identity with mammalian homologues and 29.2 to 31.5% identity with its piscine counterparts. chIL-17RA transcript expression was relatively high in the thymus and in the chicken macrophage cell line HD11. The chIL-17RA-specific small interfering RNA inhibits interleukin-6 (IL-6), IL-8, and IL-1β mRNA expression in chicken embryo fibroblast cells (but not in DF-1 cells) stimulated with chIL-17A or chIL-17F. Interaction between chIL-17RA and chIL-17A was confirmed by coimmunoprecipitation. Downregulation of chIL-17RA occurred in concanavalin A- or lipopolysaccharide-activated splenic lymphocytes but not in poly(I·C)-activated splenic lymphocytes. In Salmonella- and Eimeria-infected chickens, the expression levels of the chIL-17RA transcript were downregulated in intestinal tissues from chickens infected with two Eimeria species, E. tenella or E. maxima, that preferentially infect the cecum and jejunum, respectively. However, chIL-17RA expression was generally unchanged in Salmonella infection. These results suggest that chIL-17RA has an important role in mucosal immunity to intestinal intracellular parasite infections such as Eimeria infection.

Peyerʼs Patches Play a Protective Role in Nonsteroidal Anti-inflammatory Drug-induced Enteropathy in Mice

Peyer's patches (PPs) play a major role in mucosal immunity. However, their roles in nonsteroidal anti-inflammatory drug-induced enteropathy are poorly understood. Wild-type (WT) and PP-null mice were injected with indomethacin. Twenty-four hours later, the cellular profiles and cytokine levels in the PPs, mesenteric lymph nodes (MLNs), and lamina propria (LP) of the small intestine were measured. WT and PP-null mice were given antibiotics before indomethacin treatment to evaluate enteropathy. Naive CD4 T cells were co-cultured with CD103 or CD103 dendritic cells (DCs) to analyze the interleukin (IL)-10 expression levels. Finally, WT mice adoptively transferred with CD103 or CD103 DCs were injected with indomethacin. The proportion of CD103 DCs in PPs and MLNs and IL-10-expressing CD4 T cells of PPs and the LP increased after indomethacin treatment. The PP-null mice showed greater indomethacin-induced enteropathy, fewer CD103 DCs in their MLNs, and lower proportion of IL-10-expressing CD4 T cells of their LP than WT mice, regardless of commensal bacteria. Naive splenic CD4 T cells co-cultured with CD103 DCs isolated from the MLNs of indomethacin-injected WT mice produced a higher amount of IL-10 compared with those co-cultured with CD103 DCs. Moreover, WT mice that received CD103 DCs showed milder enteropathy than those that received CD103 DCs. PPs play a protective role in nonsteroidal anti-inflammatory drug-induced enteropathy, and this protection is associated with an increase in CD103 DCs and IL-10-producing CD4 T cells in the intestine, independent of the commensal bacteria.

Candida Vaginitis: When Opportunism Knocks, the Host Responds

Candida Vaginitis: When Opportunism Knocks, the Host Responds

Eosinophils Promote Generation and Maintenance of Immunoglobulin-A-Expressing Plasma Cells and Contribute to Gut Immune Homeostasis

Although in normal lamina propria (LP) large numbers of eosinophils are present, little is known about their role in mucosal immunity at steady state. Here we show that eosinophils are needed to maintain immune homeostasis in gut-associated tissues. By using eosinophil-deficient ΔdblGATA-1 and PHIL mice or an eosinophil-specific depletion model, we found a reduction in immunoglobulin A(+) (IgA(+)) plasma cell numbers and in secreted IgA. Eosinophil-deficient mice also showed defects in the intestinal mucous shield and alterations in microbiota composition in the gut lumen. In addition, TGF-β-dependent events including class switching to IgA in Peyer's patches (PP), the formation of CD103(+) T cells including Foxp3(+) regulatory (Treg), and also CD103(+) dendritic cells were disturbed. In vitro cultures showed that eosinophils produce factors that promote T-independent IgA class switching. Our findings show that eosinophils are important players for immune homeostasis in gut-associated tissues and add to data suggesting that eosinophils can promote tissue integrity.

Characterization and expression pattern of a novel β-defensin in common carp (Cyprinus carpio L.): implications for its role in mucosal immunity.

β-defensins are a group of cysteine-rich cationic antimicrobial peptides that play antibacterial and antiviral roles in immune systems of vertebrates. Here, we report the cloning and identification of a β-defensin 3 cDNA sequence from the common carp (Cyprinus carpio L.). Sequence alignment and phylogenetic analysis indicated that this β-defensin 3 belonged to the BD-2 group of fish. Real-time PCR showed that the β-defensin 3 mRNA was expressed in all the tissues of normal common carp that we examined and was highly expressed in the spleen and gills. When challenged with Vibrio anguillarum, the expression level of common carp β-defensin 3 mRNA was quickly upregulated in various tissues. Our results indicate that the β-defensin 3 showed markedly high constitutive expression in the gills, and significantly upregulated expression in the hindgut of the common carp after infection, suggesting it plays an important role in the innate and mucosal immunity of common carp.

The Role of T cells In Mucosal Immunity against Mycobacterium tuberculosis (Mtb) Infection: A Review of Current Understanding

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) remains one of the most important infectious diseases globally. Because Bacille Calmette-Guerin (BCG) vaccine is short of preventing transmission, the search for an efficacious vaccine to either augment that of BCG or to replace has been intensified globally. Currently, there are many candidate vaccines in different stages of clinical trials but none of these has achieved the desired efficacy to control TB. One central issue in TB immunology is lack of clear understanding as to what leads to immune protection or development of clinical disease. Tuberculosis is primarily a disease of the lungs and the main portal of entry of Mtb to the lungs and systemic organs is the respiratory tract and its mucosal surfaces. Therefore, the role of mucosal immunity against Mtb infection has been the subject of several investigations quite for some time. There is emerging evidence that mucosal immunity against TB may be critical for the control of Mtb infection and development of an efficacious vaccine. Although it is generally believed that type helper T (Th1) cells are critical for protection against Mtb infection, emerging data show that non-conventional T cells could play a vital role in protection against TB, particularly in the respiratory mucosa. In this review, current understanding on the role of various T cell subsets, with focus on lymphocytes collectively called “innate-like lymphocytes”, including gammadelta (γδ) T cells, natural killer T (NKT) cells, and mucosal-associated invariant T (MAIT) cells will be presented.

Low Levels of Peripheral CD161++CD8+ Mucosal Associated Invariant T (MAIT) Cells Are Found in HIV and HIV/TB Co-Infection

BackgroundHigh expression of CD161 on CD8+ T cells is associated with a population of cells thought to play a role in mucosal immunity. We wished to investigate this subset in an HIV and Mycobacterium tuberculosis (MTB) endemic African setting.MethodsA flow cytometric approach was used to assess the frequency and phenotype of CD161++CD8+ T cells. 80 individuals were recruited for cross-sectional analysis: controls (n = 13), latent MTB infection (LTBI) only (n = 14), pulmonary tuberculosis (TB) only (n = 9), HIV only (n = 16), HIV and LTBI co-infection (n = 13) and HIV and TB co-infection (n = 15). The impact of acute HIV infection was assessed in 5 individuals recruited within 3 weeks of infection. The frequency of CD161++CD8+ T cells was assessed prior to and during antiretroviral therapy (ART) in 14 HIV-positive patients.ResultsCD161++CD8+ T cells expressed high levels of the HIV co-receptor CCR5, the tissue-homing marker CCR6, and the Mucosal-Associated Invariant T (MAIT) cell TCR Vα7.2. Acute and chronic HIV were associated with lower frequencies of CD161++CD8+ T cells, which did not correlate with CD4 count or HIV viral load. ART was not associated with an increase in CD161++CD8+ T cell frequency. There was a trend towards lower levels of CD161++CD8+ T cells in HIV-negative individuals with active and latent TB. In those co-infected with HIV and TB, CD161++CD8+ T cells were found at low levels similar to those seen in HIV mono-infection.ConclusionsThe frequencies and phenotype of CD161++CD8+ T cells in this South African cohort are comparable to those published in European and US cohorts. Low-levels of this population were associated with acute and chronic HIV infection. Lower levels of the tissue-trophic CD161++ CD8+ T cell population may contribute to weakened mucosal immune defense, making HIV-infected subjects more susceptible to pulmonary and gastrointestinal infections and detrimentally impacting on host defense against TB.