Effects of the oral administration of the exopolysaccharide produced by Lactobacillus kefiranofaciens on the gut mucosal immunity

The probiotic effects ascribed to lactic acid bacteria (LAB) and their fermented dairy products arise not only from whole microorganisms and cell wall components but also from peptides and extracellular polysaccharides (exopolysaccharides) produced during the fermentation of milk. There is a lack of knowledge concerning the immune mechanisms induced by exopolysaccharides produced by lactic acid bacteria, which would allow a better understanding of the functional effects described to them. The aim of this study was to investigate the in vivo immunomodulating capacity of the exopolysaccharide produced by Lactobacillus kefiranofaciens by analyzing the profile of cytokines and immunoglobulins induced at the intestinal mucosa level, in the intestinal fluid and blood serum. BALB/c mice received the exopolysaccharide produced by L. kefiranofaciens for 2, 5 or 7 consecutive days. At the end of each period of administration, control and treated mice were sacrificed and the numbers of IgA+ and IgG+ cells were determined on histological slices of the small and large intestine by immunofluorescence. Cytokines (IL-4, IL-6, IL-10, IL-12, IFNgamma and TNFalpha) were also determined in the gut lamina propria as well as in the intestinal fluid and blood serum. There was an increase of IgA+ cells in the small and large intestine lamina propria, without change in the number of IgG+ cells in the small intestine. This study reports the effects of the oral administration of the exopolysaccharide produced by L. kefiranofaciens in the number of IgA+ cells in the small and large intestine, comparing simultaneously the production of cytokines by cells of the lamina propria and in the intestinal fluid and blood serum. The increase in the number of IgA+ cells was not simultaneously accompanied by an enhance of the number of IL-4+ cells in the small intestine. This finding would be in accordance with the fact that, in general, polysaccharide antigens elicit a T-independent immune response. For IL-10+, IL-6+ and IL-12+ cells, the values found were slightly increased compared to control values, while IFNgamma+ and TNFalpha+ cells did not change compared to control values. The effects observed on immunoglobulins and in all the cytokines assayed in the large intestine after kefiran administration were of greater magnitude than the ones observed in the small intestine lamina propria, which may be due to the saccharolytic action of the colonic microflora. In the intestinal fluid, only IL-4 and IL-12 increased compared to control values. In blood serum, all the cytokines assayed followed a pattern of production quite similar to the one found for them in the small intestine lamina propria. We observed that the exopolysaccharide induced a gut mucosal response and it was able to up and down regulate it for protective immunity, maintaining intestinal homeostasis, enhancing the IgA production at both the small and large intestine level and influencing the systemic immunity through the cytokines released to the circulating blood.     

Caloric restriction reduces IgA levels and modifies cytokine mRNA expression in mouse small intestine

The aim of this study was to determine the effect of caloric restriction (CR) in mouse small intestine on the production and secretion of immunoglobulin (Ig) A, the population of lymphocytes in the lamina propria, and the expression of cytokines that mediate and regulate innate and adaptive immunity. One group of young Balb/c mice was fed ad libitum, while the CR group was fed ad libitum and fasted on alternate days. When mice were six months old, IgA levels in the proximal small intestine were quantified by enzyme-linked immunosorbent assay, while the number of IgA containing cells, CD4⁺ T cells and CD8⁺ T cells in the duodenal mucosa was determined by immunohistochemistry. Furthermore, the expression of several intestinal cytokines, the genes for α-chain IgA, and the polymeric Ig receptor (pIgR) were analyzed by real-time polymerase chain reaction. CR decreased the levels of IgA in the intestine, apparently a consequence of a reduced number of IgA⁺ cells in the lamina propria that decrease the production and secretion of this Ig, and a reduced secretion of S-IgA into the bile, which in turn discharges into the proximal intestine. Contrarily, CR increased the expression of genes for α-chain IgA, and the pIgR, indicating that transport of IgA was not a key factor in the decrease of this Ig. Additionally, CR modified the expression of genes for tumor necrosis factor-α, interferon-γ, tumor growth factor-β, interleukin (IL)-2 and IL-10, all of which regulate the synthesis of IgA and pIgR, the inflammatory response, and the immune response in the intestine.     

Striking phenotypic and functional differences in lamina propria lymphocytes from the large and small intestine of mice

Although intraepithelial T lymphocytes of the large intestine (LI) are known to differ from those of the small intestine (SI) in phenotype and function, differences in LI and SI lamina propria (LP) lymphocyte populations have not been clearly established. In this work we found striking phenotypic differences between SI and LI LP lymphocyte populations from Balb/c mice analyzed by flow cytometry. In the LI most lymphocytes were B cells and the predominant T cells were TCR-alpha beta+, CD8+. In contrast, in the SI most T lymphocytes were CD4+ expressing TCR-alpha beta+, although a higher proportion expressed TCR-gamma delta+ than in the LI. In T cells the expression of adhesion molecules and cytokines was also different between SI and LI. The proportion of LP T cells expressing alpha4beta7 and L-selectin was higher in the LI than in the SI; whereas a greater proportion of cells expressing alpha(E)beta7 were detected in the SI than in LI. Higher proportions of T cells expressing L-selectin and alpha4beta1 were detected in the intraepithelial compartment of the LI than that of the SI, whereas the number of T cells expressing alpha(E)beta7 was much higher in the SI than in the LI. The proportion of T cells spontaneously producing IL-2, IFN gamma, and IL-4 at the intraepithelial and lamina propria, in the small and large intestine, was different indicating that distinctive functional features exist in the lymphocyte populations residing at the different intestinal compartments.     

Interaction of lipopolysaccharide with human small intestinal lamina propria fibroblasts favors neutrophil migration and peripheral blood mononuclear cell adhesion by the production of proinflammatory mediators and adhesion molecules

Fibroblasts are important effector cells having a potential role in augmenting the inflammatory responses in various diseases. In infantile diarrhea caused by enteropathogenic Escherichia coli (EPEC), the mechanism of inflammatory reactions at the mucosal site remains unknown. Although the potential involvement of fibroblasts in the pathogenesis of cryptococcus-induced diarrhea in pigs has been suggested, the precise role of lamina propria fibroblasts in the cellular pathogenesis of intestinal infection and inflammation caused by EPEC requires elucidation. Earlier we reported the lipopolysaccharide (LPS)-induced cell proliferation, and collagen synthesis and downregulation of nitric oxide in lamina propria fibroblasts. In this report, we present the profile of cytokines and adhesion molecules in the cultured and characterized human small intestinal lamina propria fibroblasts in relation to neutrophil migration and adhesion in response to lipopolysaccharide (LPS) extracted from EPEC 055:B5. Upon interaction with LPS (1-10 micrograms/ml), lamina propria fibroblasts produced a high level of proinflammatory mediators, interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, tumor necrosis factor (TNF)-alpha and cell adhesion molecules (CAM) such as intercellular cell adhesion molecule (ICAM), A-CAM, N-CAM and vitronectin in a time-dependent manner. LPS induced cell-associated IL-1alpha and IL-1beta, and IL-6, IL-8 and TNF-alpha as soluble form in the supernatant. Apart from ICAM, vitronectin, A-CAM, and N-CAM proteins were strongly induced in lamina propria fibroblasts by LPS. Adhesion of PBMC to LPS-treated lamina propria fibroblasts was ICAM-dependent. LPS-induced ICAM expression in lamina propria fibroblasts was modulated by whole blood, PBMC and neutrophils. Conditioned medium of LPS-treated lamina propria fibroblasts remarkably enhanced the neutrophil migration. The migration of neutrophils was inhibited by anti-IL-8 antibody. Co-culture of fibroblasts with neutrophils using polycarbonate membrane filters exhibited time-dependent migration of neutrophils. These findings indicate that the coordinate production of proinflammatory cytokines and adhesion molecules in lamina propria fibroblasts which do not classically belong to the immune system can influence the local inflammatory reactions at the intestinal mucosal site during bacterial infections and can influence the immune cell population residing in the lamina propria.     

Tissue distribution of immunoglobulin-secreting cells in normal and IgA-deficient chickens.

A reverse hemolytic plaque assay was employed to enumerate lymphoid cells actively secreting either immunoglobulin (Ig)G, IgA, or IgM in the small intestine, lungs, and lymphoid organs of normal and IgA-deficient chickens. In normal birds, intestinal lamina propria lymphocytes were proportionately richest in cells secreting IgG and IgA whereas the bone marrow was richest in IgM-secreting cells. The highest ratio of IgA to IgG secreting cells was also found in the lamina propria lymphocytes of the intestine (0.9), followed by the IgA to IgG ratios in the intestinal epithelium (0.31), and the lungs (0.19). The IgA to IgG ratios in the bone marrow (0.08) and the spleen (0.02) were considerably lower. Thus, both the intestine and the lungs were relatively enriched in cells actively secreting IgA. These IgA-secreting cells are the likely source of the IgA found in such quantities in intestinal and respiratory secretions. The tissue distribution of Ig-secreting cells was also studied in two generations of birds with experimentally induced IgA deficiency. There was a striking diminution of IgA-secreting cells in all tissues, including the intestine and lungs, whereas cells secreting IgG and IgM were normal or increased. The lack of IgA-secreting cells in these birds represents the effects of donor suppressor T cells having specificity for IgA.     

CC chemokine ligands 25 and 28 play essential roles in intestinal extravasation of IgA antibody-secreting cells

CCL25 (also known as thymus-expressed chemokine) and CCL28 (also known as mucosae-associated epithelial chemokine) play important roles in mucosal immunity by recruiting IgA Ab-secreting cells (ASCs) into mucosal lamina propria. However, their exact roles in vivo still remain to be defined. In this study, we first demonstrated in mice that IgA ASCs in small intestine expressed CCR9, CCR10, and CXCR4 on the cell surface and migrated to their respective ligands CCL25, CCL28, and CXCL12 (also known as stromal cell-derived factor 1), whereas IgA ASCs in colon mainly expressed CCR10 and CXCR4 and migrated to CCL28 and CXCL12. Reciprocally, the epithelial cells of small intestine were immunologically positive for CCL25 and CCL28, whereas those of colon were positive for CCL28 and CXCL12. Furthermore, the venular endothelial cells in small intestine were positive for CCL25 and CCL28, whereas those in colon were positive for CCL28, suggesting their direct roles in extravasation of IgA ASCs. Consistently, in mice orally immunized with cholera toxin (CT), anti-CCL25 suppressed homing of CT-specific IgA ASCs into small intestine, whereas anti-CCL28 suppressed homing of CT-specific IgA ASCs into both small intestine and colon. Reciprocally, CT-specific ASCs and IgA titers in the blood were increased in mice treated with anti-CCL25 or anti-CCL28. Anti-CXCL12 had no such effects. Finally, both CCL25 and CCL28 were capable of enhancing alpha4 integrin-dependent adhesion of IgA ASCs to mucosal addressin cell adhesion molecule-1 and VCAM-1. Collectively, CCL25 and CCL28 play essential roles in intestinal homing of IgA ASCs primarily by mediating their extravasation into intestinal lamina propria.     

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.     

Lactobacillus gasseri SBT2055 Induces TGF-β Expression in Dendritic Cells and Activates TLR2 Signal to Produce IgA in the Small Intestine

Probiotic bacteria provide benefits in enhancing host immune responses and protecting against infection. Induction of IgA production by oral administration of probiotic bacteria in the intestine has been considered to be one reason for this beneficial effect, but the mechanisms of the effect are poorly understood. Lactobacillus gasseri SBT2055 (LG2055) is a probiotic bacterium with properties such as bile tolerance, ability to improve the intestinal environment, and it has preventive effects related to abdominal adiposity. In this study, we have found that oral administration of LG2055 induced IgA production and increased the rate of IgA⁺ cell population in Peyer''s patch and in the lamina propria of the mouse small intestine. The LG2055 markedly increased the amount of IgA in a co-culture of B cells and bone marrow derived dendritic cells (BMDC), and TLR2 signal is critical for it. In addition, it is demonstrated that LG2055 stimulates BMDC to promote the production of TGF-β, BAFF, IL-6, and IL-10, all critical for IgA production from B cells. Combined stimulation of B cells with BAFF and LG2055 enhanced the induction of IgA production. Further, TGF-β signal was shown to be critical for LG2055-induced IgA production in the B cell and BMDC co-culture system, but TGF-β did not induce IgA production in a culture of only B cells stimulated with LG2055. Furthermore, TGF-β was critical for the production of BAFF, IL-6, IL-10, and TGF-β itself from LG2055-stimulated BMDC. These results demonstrate that TGF-β was produced by BMDC stimulated with LG2055 and it has an autocrine/paracrine function essential for BMDC to induce the production of BAFF, IL-6, and IL-10.     

Clostridium perfringens Epsilon Toxin Increases the Small Intestinal Permeability in Mice and Rats

Epsilon toxin is a potent neurotoxin produced by Clostridium perfringens types B and D, an anaerobic bacterium that causes enterotoxaemia in ruminants. In the affected animal, it causes oedema of the lungs and brain by damaging the endothelial cells, inducing physiological and morphological changes. Although it is believed to compromise the intestinal barrier, thus entering the gut vasculature, little is known about the mechanism underlying this process. This study characterizes the effects of epsilon toxin on fluid transport and bioelectrical parameters in the small intestine of mice and rats. The enteropooling and the intestinal loop tests, together with the single-pass perfusion assay and in vitro and ex vivo analysis in Ussing''s chamber, were all used in combination with histological and ultrastructural analysis of mice and rat small intestine, challenged with or without C. perfringens epsilon toxin. Luminal epsilon toxin induced a time and concentration dependent intestinal fluid accumulation and fall of the transepithelial resistance. Although no evident histological changes were observed, opening of the mucosa tight junction in combination with apoptotic changes in the lamina propria were seen with transmission electron microscopy. These results indicate that C. perfringens epsilon toxin alters the intestinal permeability, predominantly by opening the mucosa tight junction, increasing its permeability to macromolecules, and inducing further degenerative changes in the lamina propria of the bowel.     

Intraepithelial infiltration of eosinophils and their contribution to the elimination of adult intestinal nematode,Strongyloides venezuelensis in mice

Eosinophils were examined for the capacity of attacking Strongyloides venezuelensis adult worms in the intestinal mucosa by using interleukin (IL)-5 transgenic mice. In IL-5 transgenic mice, most of the subcutaneously inoculated infective larvae were killed during migration, and only a few worms could reach the small intestine. When the same number of adult worms were surgically implanted in the small intestine of IL-5 transgenic and control mice, fecal egg output as well as the number of adult worms recovered from the intestine was significantly lower in IL-5 transgenic mice. In the intestinal mucosa of IL-5 transgenic mice, large number of eosinophils was present in the lamina propria even before adult worm implantation. The number of eosinophils increased significantly as early as 24 h after implantation and tripled by day 3, whereas mucosal eosinophilia remained low in wild-type mice. Most notably, eosinophils infiltrated into the intestinal epithelium and surrounded adult worms in IL-5 transgenic mice, which was never seen in wild-type control mice. However, IL-5 transgenic mice required the same period as normal mice to completely expel implanted adult worms. The amount of specific IgA as well as total IgA in the stool was high in IL-5 transgenic mice before adult worm implantation, and dropped rapidly after adult worm implantation. The present study suggests that eosinophils are capable of attacking adult nematodes in the intestinal epithelia, probably in conjunction with secretory IgA, although they are not enough for the complete worm expulsion.     

Effect of a cocoa diet on the small intestine and gut-associated lymphoid tissue composition in an oral sensitization model in rats

Previous studies have attributed to the cocoa powder the capacity to attenuate the immune response in a rat oral sensitization model. To gain a better understanding of cocoa-induced mechanisms at small intestinal level, 3-week-old female Lewis rats were fed either a standard diet or a diet containing 10% cocoa for 4 weeks with or without concomitant oral sensitization with ovalbumin (OVA). Thereafter, we evaluated the lymphocyte composition of the Peyer's patches (PPL), small intestine epithelium (IEL) and lamina propria (LPL). Likewise, gene expression of several immune molecules was quantified in the small intestine. Moreover, histological samples were used to evaluate the proportion of goblet cells, IgA+ cells and granzyme+ cells as well. In cocoa-fed animals, we identified a five-time reduction in the percentage of IgA+ cells in intestinal tissue together with a decreased proportion of TLR4+ IEL. Analyzing the lymphocyte composition, almost a double proportion of TCRγδ+ cells and an increase of NK cell percentage in PPL and IEL were found. In addition, a rise in CD25+, CD103+ and CD62L− cell proportions was observed in CD4+ PPL from cocoa-fed animals, along with a decrease in gene expression of CD11b, CD11c and IL-10. These results suggest that changes in PPL and IEL composition and in the gene expression induced by the cocoa diet could be involved, among other mechanisms, on its tolerogenic effect.     

Consumo crónico de edulcorantes en ratones y su efecto sobre el sistema inmunitario y la microbiota del intestino delgado

Introduction:

Sweeteners are additives used in different foods. They can be natural (sucrose and stevia) or artificial (sucralose). Currently, they are routinely consumed in multiple products and their effects on the mucosa of the small intestine and its microbiota are still controversial.

Objective:

To relate the consumption of sweeteners and their effect on the immune system and the microbiota of the small intestine in CD1 mice.

Materials and methods:

We used 54 three-week-old CD1 mice divided into three groups in the experiments: 1) A group of three weeks without treatment, 2) a group treated for six weeks, and 3) a group treated for 12 weeks using sucrose, sucralose, and stevia. We obtained CD19+ B lymphocytes, IgA+ antibodies, transforming growth factor-beta (TGF-b), and interleukins 12 and 17 (IL-12 and -17) from Peyer''s patches and lamina propria cells while DNA was obtained from intestinal solids to identify bacterial species.

Results:

After 12 weeks, sucrose and sucralose consumption caused a reduction in bacterial communities with an increase in CD19+, a decrease in IgA+ and TGF-b, and an increase in IL-12 and -17 in the Peyer''s patches while in the lamina propria there was an increase in all parameters. In contrast, stevia led to an improvement in bacterial diversity and percentage of CD19+ lymphocytes with minimal increase in IgA+, TGF-b, and IL-12, and a decrease in IL-17.

Conclusion:

Sucrose and sucralose caused negative alterations in bacterial diversity and immune parameters after 12 weeks; in contrast, stevia was beneficial for the intestinal mucosa.     

IgA plasma cells express the negative regulatory co-stimulatory molecule programmed cell death 1 ligand and have a potential tolerogenic role in the intestine

To maintain immune homeostasis in the intestine, the intestinal immune system has evolved several tolerogenic mechanisms toward intestinal microflora and food antigens. Although programmed cell death-1 (PD-1) protein has been implicated in immunological tolerance in the intestine and gut-associated lymphoid tissues (GALTs), distribution of its ligands PD-L1 and PD-L2 in the small intestine lamina propria (LP) are unknown. We investigated PD-L1 expression in intestinal LP and found that IgA plasma cells (PCs) were major PD-L1 expressing cells. PD-L1 expression levels on IgA PCs were higher than that on IgG PCs in peripheral lymphoid tissues. IgA PCs expressed antigen-presenting molecule MHC class II and co-stimulatory molecules CD80, CD86, and PD-L2. IgA PCs isolated from intestinal LP exhibited antigen presentation activity, and in the presence of TGF-β induced FoxP3⁺ regulatory T cells, but not IFN-γ⁺ Th1 cells, from naïve T cells. Thus, IgA PCs in the intestine may be involved in an immune regulatory role in the intestinal immune system.     

Immunological differences in intestine and rectum of Atlantic cod (Gadus morhua L.)

The defence system of the distal gut (hindgut and rectum) of Atlantic cod, (Gadus morhua L.) was studied using (immuno)histochemical, electron microscopical and real-time quantitative PCR techniques. The uptake and transport of macromolecules in the intestinal epithelium was also investigated.In this study we observed that cod has many and large goblet cells in its intestinal epithelium and that IgM⁺ cells are present in the lamina propria and their number is considerably higher in the rectum than in the intestine. Myeloperoxidase staining revealed low numbers of granulocytes in and under the epithelium of the distal intestine, whereas high numbers were found clustered in the submucosa of the rectum. Electron microscopy not only confirmed these observations, but also revealed the presence of lymphoid cells and macrophages within the intestinal epithelium. Acid phosphatase staining demonstrated more positive macrophage-like cells in the rectum than in the distal intestine. Antigen uptake studies showed a diffused absorption of horse radish peroxidase (HRP) and LTB-GFP, whereas ferritin uptake could not be detected.Basal gene expression of cytokines (IL-1β, IL-8 and IL-10) and immune relevant molecules (hepcidin and BPI/LPB) were compared in both the intestine and rectum and revealed approximately 2–9 times higher expression in the rectum, of which IL-1β expression showed the most prominent difference.The present results clearly indicate that intestinal immunity is very prominent in the rectum of cod.     

Intestinal CD103+ Dendritic Cells Are Key Players in the Innate Immune Control of Cryptosporidium parvum Infection in Neonatal Mice

Cryptosporidium parvum is a zoonotic protozoan parasite found worldwide, that develops only in the gastrointestinal epithelium and causes profuse diarrhea. Using a mouse model of C. parvum infection, we demonstrated by conditional depletion of CD11c+ cells that these cells are essential for the control of the infection both in neonates and adults. Neonates are highly susceptible to C. parvum but the infection is self-limited, whereas adults are resistant unless immunocompromised. We investigated the contribution of DC to the age-dependent susceptibility to infection. We found that neonates presented a marked deficit in intestinal CD103+ DC during the first weeks of life, before weaning, due to weak production of chemokines by neonatal intestinal epithelial cells (IEC). Increasing the number of intestinal CD103+ DC in neonates by administering FLT3-L significantly reduced susceptibility to the infection. During infections in neonates, the clearance of the parasite was preceded by a rapid recruitment of CD103+ DC mediated by CXCR3-binding chemokines produced by IEC in response to IFNγ. In addition to this key role in CD103+ DC recruitment, IFNγ is known to inhibit intracellular parasite development. We demonstrated that during neonatal infection CD103+ DC produce IL-12 and IFNγ in the lamina propria and the draining lymph nodes. Thus, CD103+DC are key players in the innate immune control of C. parvum infection in the intestinal epithelium. The relative paucity of CD103+ DC in the neonatal intestine contributes to the high susceptibility to intestinal infection.

Authors Summary

Dendritic cells are central to the defense against mucosal pathogens. They are numerous and form a uniform network in the intestinal mucosa of adults, but are poorly characterized in the intestine of neonates. Young animals are more susceptible than adults to intestinal pathogens, such as Cryptosporidium parvum, a zoonotic agent distributed worldwide that develops in the epithelium of the small intestine causing profuse diarrhea. We show that dendritic cells are scarce in the small intestine of neonates until weaning and that increasing their numbers in vivo results in increased resistance to infection. Using a conditional depletion model we demonstrate that the presence of dendritic cells is necessary for the control of the infection in both neonates and adults. During infection in neonates, dendritic cells are rapidly recruited into the intestine by chemokines produced by the epithelium and produce interferon gamma, a cytokine that inhibits parasite development in epithelial cells. Thus, the low number of dendritic cells in the intestinal mucosa of neonates is responsible for their sensitivity to cryptosporidiosis, and probably contributes to the general susceptibility of neonates to intestinal diseases.     

IL-36 receptor is expressed by human blood and intestinal T lymphocytes and is dose–dependently activated via IL-36β and induces CD4+ lymphocyte proliferation

We show that IL-36R is expressed by T (CD4+ and CD8+) and B (CD19+) lymphocytes in human blood and also by CD4+ T lymphocytes in the intestinal lamina propria. IL-36R protein was mostly stored in the cytoplasm of CD4 lymphocytes and B cells, during steady state conditions and the greatest expression of IL-36R mRNA was measured in CD4+ (T helper) lymphocytes. IL-36 β, which functions via IL-36R induced rapid and significant (P < 0.05) proliferation of CD4+ lymphocytes, within 48 h. IL-36R expression was also maintained on the surface of circulating CD4+ lymphocytes which enter the intestinal lamina propria.In conclusion our study is the first to show that (1) all human blood lymphocytes express IL-36R; (2) IL-36R expression is maintained by circulating CD4+ lymphocytes which enter the intestinal lamina propria and (3) IL-36R/IL-36 β induces rapid CD4 lymphocyte proliferation. The possible significance of these results in the context of human disease is discussed.     

B-lymphocyte responses in the large intestine and mesenteric lymph nodes of mice infected with Eimeria falciformis (Apicomplexa)

B-cell responses of 3 immunoglobulin isotypes (IgA, IgG, and IgM) were investigated in the large intestine and mesenteric lymph nodes (MLN) of naive or immune mice after inoculation of oocysts of Eimeria falciformis. Primary and anamnestic IgA and IgG lymphocyte responses to E. falciformis occurred in the large intestine of nonimmune and immune mice, respectively. IgA-containing lymphocytes (IgAc) were the largest population of responding B cells in the large intestine. In infected mice, IgAc accumulated in the apical portion of the lamina propria, whereas IgG-containing lymphocytes (IgGc) were more numerous at the base of the lamina propria. No significant increase in the number of IgM-containing lymphocytes (IgMc) was observed in the lamina propria of the large intestine. Primary but no anamnestic B-cell responses occurred in the MLN, and immune mice actually had reduced numbers of IgAc and IgGc in the MLN when compared with naive mice. IgGc were the largest population of responding B cells in the MLN. Thus, IgAc appear to accumulate preferentially at the site of parasite development, whereas IgGc are primarily localized deeper in the lamina propria of the large intestine and in the draining lymph nodes of mice infected with E. falciformis.     

Prenatal blockage of lymphotoxin beta receptor and TNF receptor p55 signaling cascade resulted in the acceleration of tissue genesis for isolated lymphoid follicles in the large intestine

Signaling by lymphotoxin (LT) and TNF is essential for the organogenesis of secondary lymphoid tissues in systemic and mucosal compartments. In this study, we demonstrated that the progeny of mice treated with fusion protein of LTbetaR and IgGFc (LTbetaR-Ig) or LTbetaR-Ig plus TNFR55-Ig (double Ig) showed significantly increased numbers of isolated lymphoid follicles (ILF) in the large intestine. Interestingly, double Ig treatment accelerated the maturation of large intestinal ILF. Three-week-old progeny of double Ig-treated mice showed increased numbers of ILF in the large intestine, but not in the small intestine. Furthermore, alteration of intestinal microflora by feeding of antibiotic water did not affect the increased numbers of ILF in the large intestine of double Ig-treated mice. Most interestingly, mice that developed numerous ILF also had increased levels of activation-induced cytidine deaminase expression and numbers of IgA-expressing cells in the lamina propria of the large intestine. Taken together, these results suggest that ILF formation in the large intestine is accelerated by blockage of LTbetaR and TNFR55 signals in utero, and ILF, like colonic patches, might play a role in the induction of IgA response in the large intestine.     

Trichinella spiralis: peroxidase activity in isolated cells from the rat intestine

An understanding of physiologic events underlying resistance to parasitic worms depends on a knowledge of metabolic interactions between parasites and specific cells at the host-parasite interface. In the case of invasive intestinal parasites this interaction involves contact with epithelial cells and cells of the lamina propria. This investigation deals with the collection of epithelial cells and lamina propria cells from the small intestine of control rats and rats infected with the nematode, Trichinella spiralis, and measurement of peroxidase activity in these cells. Lamina propria cells were isolated by collagenase digestion of everted gut segments previously denuded of epithelium by treatment with hyaluronidase. Mean peroxidase activity in homogenates of lamina propria cells was equivalent to 40 nmoles H₂O₂ decomposed/min/mg of cell protein from control rats compared to 413 nmoles from infected animals. Epithelial cell peroxidase activity in homogenates of epithelial cells from both control and infected rats was less than 2 nmoles H₂O₂ decomposed/min/mg cell protein. The degree of contamination of lamina propria cells with epithelial cells was determined by measuring disaccharidase activity in both cell populations. The specific activity of maltase, sucrase, and trehalase in lamina propria cells was between 10 and 17% of that in epithelial cells. This work is a requisite for a study in which the role of intestinal cell peroxidase in resistance to Trichinella will be evaluated.