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The adaptive immune system of all jawed vertebrates relies on the presence of B and T cell lymphocytes that aggregate in specific body sites to form primary and secondary lymphoid structures. Secondary lymphoid organs include organized MALT (O-MALT) such as the tonsils and Peyer patches. O-MALT became progressively organized during vertebrate evolution, and the TNF superfamily of genes has been identified as essential for the formation and maintenance of O-MALT and other secondary and tertiary lymphoid structures in mammals. Yet, the molecular drivers of O-MALT structures found in ectotherms and birds remain essentially unknown. In this study, we provide evidence that TNFSFs, such as lymphotoxins, are likely not a universal mechanism to maintain O-MALT structures in adulthood of teleost fish, sarcopterygian fish, or birds. Although a role for TNFSF2 (TNF-α) cannot be ruled out, transcriptomics suggest that maintenance of O-MALT in nonmammalian vertebrates relies on expression of diverse genes with shared biological functions in neuronal signaling. Importantly, we identify that expression of many genes with olfactory function is a unique feature of mammalian Peyer patches but not the O-MALT of birds or ectotherms. These results provide a new view of O-MALT evolution in vertebrates and indicate that different genes with shared biological functions may have driven the formation of these lymphoid structures by a process of convergent evolution.

The impact of food antigens on intestinal homeostasis and immune function is poorly understood. Here, we explored the impact of dietary antigens on the phenotype and fate of intestinal T cells. Physiological uptake of dietary proteins generated a highly activated CD44(+)Helios(+)CD4(+) T cell population predominantly in Peyer patches. These cells are distinct from regulatory T cells and develop independently of the microbiota. Alimentation with a protein-free, elemental diet led to an atrophic small intestine with low numbers of activated T cells, including Tfh cells and decreased amounts of intestinal IgA and IL-10. Food-activated CD44(+)Helios(+)CD4(+) T cells in the Peyer patches are controlled by the immune checkpoint molecule PD-1. Blocking the PD-1 pathway rescued these T cells from apoptosis and triggered proinflammatory cytokine production, which in IL-10–deficient mice was associated with intestinal inflammation. In support of these findings, our study of patients with Crohn’s disease revealed significantly reduced frequencies of apoptotic CD4(+) T cells in Peyer patches as compared with healthy controls. These results suggest that apoptosis of diet-activated T cells is a hallmark of the healthy intestine.

International audience; Innate lymphoid cells (ILCs) are tissue-resident lymphocytes that lack antigen-specific receptors and exhibit innate effector functions such as cytokine production that play an important role in immediate responses to pathogens especially at mucosal sites. Mouse and human ILC subsets have been extensively characterized in various tissues and in blood. In this study, we present the first characterization of ILCs and ILC subsets in rat gut and secondary lymphoid organs using flow cytometry and single cell RNA sequencing. Our results show that phenotype and function of rat ILC subsets are conserved as compared to human and mouse ILCs. However, and in contrast to human and mouse, our study unexpectedly revealed that ILC2 and not ILC3 was the dominant ILC subset in the rat intestinal lamina propria. ILC2 predominance in the gut was independent of rat strain, sex or housing facility. In contrast, ILC3 was the predominant ILC subset in mesenteric lymph nodes and Peyer patches. In conclusion, our study demonstrates that in spite of highly conserved phenotype and function between mice, rat and humans, the distribution of ILC subsets in the intestinal mucosa is dependent on the species likely in response to both genetic and environmental factors.

Background Kabuki syndrome (KS) is commonly caused by mutations in the histone-modifying enzyme lysine methyltransferase 2D (KMT2D). Immune dysfunction is frequently observed in individuals with KS, but the role of KMT2D in immune system function has not been identified. Objective We sought to understand the mechanisms driving KS-associated immune deficiency (hypogammaglobulinemia [low IgA], splenomegaly, and diminished immunization responses). Methods We performed a comprehensive evaluation of humoral immunity and secondary lymphoid tissues in an established KS (Kmt2d+/βGeo) mouse model and validated select findings in a patient with KS. Results Compared with wild-type littermates, Kmt2d+/βGeo mice demonstrated deficiencies in multiple B-cell lineages and reduced serum IgA and elevated IgM levels across multiple ages. The bone marrow, spleen, and intestine of Kmt2d+/βGeo mice contained diminished numbers of IgA-secreting cells, while elevated germinal center B cells were found in the mesenteric lymph node and Peyer patches. Kmt2d+/βGeo mice have decreased size and numbers of Peyer patches, a finding confirmed in human samples. We identified deficiency of Itgb7 RNA and protein expression, a gene encoding an adhesion protein that mediates intestinal homing, and we demonstrated KMT2D-dependent control of ITGB7 expression in a human cell line. Conclusions Kmt2d haploinsufficiency has broad deleterious effects on B-cell differentiation, specifically hampering gut lymphocyte homing and IgA+ plasma cell differentiation. Intestinal lymphoid defects caused by ITGB7 deficiency have not previously been recognized in KS, and these results provide new mechanistic insights into the pathogenesis of KS-associated immune deficiency.

Aim: The present study was aimed to elucidate the histomorphology of ileal and jejunal Peyer’s patches in the small intestine of buffalo calves and their structural comparison. Materials and Methods: The study was conducted on neonatal (n=10) and pre-pubertal (n=10) buffalo calves. The age of the postnatal buffalo calves was estimated by their temporary and permanent dentition. Results: The study revealed that several layers of oval to elongate elliptical lymphoid follicles were observed in submucosa on the anti-mesenteric side in the ileum of early neonatal calves. However, the follicles at this age, in jejunum were of all shapes present within one layer. The interfollicular space was occupied by the interfollicular tissue, which was diffuse and wider around jejunal lymphoid follicles as compared to ileal lymphoid follicles. However, toward the pubertal stage, the number of layers of lymphoid follicles was reduced in ileum due to involution while it remained similar in number in jejunum at this stage. Conclusion: The ileal Peyer’s patches were found to have started involution more or less around reaching puberty, whereas the jejunal Peyer’s patches appear to be functional throughout the lifespan of the animal.

Zearalenone (ZEN) is one of the most active natural estrogenic compounds that induces apoptosis. This study has been prompted by the widespread occurrence of ZEN in food and feed and limited knowledge about the effects of exposure to low doses of ZEN on the immune system. The aim of the study was to verify the hypothesis that low doses of ZEN contribute to induction of apoptosis and inhibition of proliferation in lymphocytes of the germinal centers (GC) of ileal Peyer's patches (IPP) in pigs. The experiment was performed on 30 female Polish Large White pigs, aged 2 months, with body weight of 15-18 kg, divided into two groups: control (C, n=15) and experimental (Z, n=15). On days 14, 28 and 42 of exposure to ZEN (100 μg kg−1 feed day−1), apoptosis in IPP GC was evaluated histologically in HE-stained specimens, immunohistochemically by active caspase-3 staining and in mononucleosome and oligonucleosome detection-based ELISA. Proliferation was evaluated histologically by mitosis detection in HE-stained specimens, immunohistochemically by PCNA staining and in the MTT tetrazolium salt colorimetric assay detecting mitogenic responses of B cells to LPS. Exposure to low doses of ZEN for several weeks intensified apoptosis and weakened proliferation in IPP lymphocytes. ZEN influences gut-associated lymphoid tissue (GALT) by decreasing the expression of CD21+ on B cells and by increasing the percentage of B1 cell populations.

Probiotics such as L. plantarum WCFS1 can modulate immune responses in healthy subjects but how this occurs is still largely unknown. Immune-sampling in the Peyer Patches has been suggested to be one of the mechanisms. Here we studied the systemic and intestinal immune effects in combination with a trafficking study through the intestine of a well-established immunomodulating probiotic, i.e. L. plantarum WCFS1. We demonstrate that not more than 2–3 bacteria were sampled and in many animals not any bacterium could be found in the PP. Despite this, L. plantarum was associated with a strong increase in infiltration of regulatory CD103+ DCs and generation of regulatory T cells in the spleen. Also, a reduced splenic T helper cell cytokine response was observed after ex vivo restimulation. L. plantarum enhanced Treg cells and attenuated the T helper 2 response in healthy mice. We demonstrate that, in healthy mice, immune sampling is a rare phenomenon and not required for immunomodulation. Also in absence of any sampling immune activation was found illustrating that host-microbe interaction on the Peyer Patches was enough to induce immunomodulation of DCs and T-cells.

Introduction: The vagal network has a major potential role in the immune-life of Peyer’s patches, but there is no satisfying information if vagal ischemia causes Peyer’s patches (PP) disruption following subarachnoid hemorrhage (SAH). Methods: Twenty-two rabbits were used as control (GI, n=5), "sham" (GII, n=5), and SAH (GIII, n=12) groups in this experiment. 0.5 cc saline for GII and 0.5 cc autologous blood for GIII was injected into cisterna magna of the rabbits. Four weeks later, they were euthanized. Their brains, vagal nerves, nodose ganglia, Peyer’s patches, and intestines were examined, using stereological methods. The Peyer’s patches volumes (PPVs)/intestine volume per cubic millimeter was accepted as PP injury score based on a total of 10 points. Results: The mean degenerated neuron densities of the nodose ganglia and degenerated axon densities of vagal nerves were 5±2/mm3 and 6±2/mm2 in the GI, 13±4/mm3 and 89±16/mm2 in the GII and 321±83/mm3 and 293±88/mm2 in GIII. The mean PPVs and PP score were 8±1×106 µm3 /mm3 and 0-3 in the GI, 10±3×106 µm3 /mm3 and 4-7 in the GII, and 21±5×106 µm3 /mm3 and 8-10 in GIII. P0.05 in GI/GII were noted. Conclusion: Vagal ischemia/insult may be responsible for PP denervation, and injury-induced dangerous intestinal immunodeficiency following SAH.

Most research studies investigating the estrogenic effects of zearalenone (ZEN) focus on the mycotoxin’s effect on the reproductive system. Since estrogen receptors are present on various types of immunocompetent cells, ZEN can also modify diverse immune functions. This study analyzed immunocompetent cells isolated from Peyer’s patches in the ileum of pigs administered ZEN in the estimated daily dose of 8 μg kg-1 BW (equivalent of 100 μg kg-1 feed per day-1). The objective of the study was to determine whether long-term exposure to low ZEN doses below the NOEL threshold leads to changes in the percentages of lymphocyte subpopulations and cytokine secretion by Th1 (IL-2, IFN-γ) and Th2 (IL-4 and IL-10) lymphocytes in Peyer’s patches of the ileum after in vitro stimulation with lipopolysaccharides (LPS). Immunocompetent cells isolated from Payer’s patches on experimental days 0, 14, 28 and 42 were cultured in vitro and stimulated with LPS. The presence of IL-2, IFN-γ, IL-4 and IL-10 in culture media was determined by the ELISA method. The results of the study indicate that ZEN inhibits IL-2 and IFN-γ secretion and stimulates IL-4 and IL-10 production by Th1 and Th2 lymphocytes by shifting the Th1/Th2 balance towards the humoral immune response. The above can promote allergic responses, as demonstrated by the increase in the size of B1 cell populations producing more autoantibodies. ZEN can also lower resistance to viruses and tumors by inhibiting the proliferation of NK cells and IFN-γ secretion.

International audience; In this report we employed laser-capture microdissection (LCM) coupled to qPCR technology and bioinformatic analysis to characterize, for the first time, the response of Peyer's patches (PP) from orally infected animals to Salmonella typhimurium, in a model of non-typhoidal salmonellosis. Pathogen was highly found in the cytoplasm of phagocytes in PP and differential gene expression analysis indicated an up-regulation of proinflammatory molecules, establishment of a Th1 driven response and triggering of DC and T-cell activity. Furthermore, predictions by bioinformatic analysis pointed to an activation of processes regarding stimulation and maturation of DC, influx of leukocytes in tissue and T lymphocytes priming and differentiation. In short, the approach used in this study proved to be a promising strategy to explore infectious processes. Indeed, it revealed an effective induction of innate and adaptive immune mechanisms in swine PP which appear to be distinct from those observed in mesenteric lymph nodes and closely related to response of gut mucosa.

The ileal Peyers patches (IPP) of newborn germfree (GF) piglets were isolated into blind loops and the piglets colonized with a defined probiotic microflora. After 5 weeks, IgA levels in the intestinal lavage (IL) of loop piglets remained at GF levels and IgM comprised ∼70% while in controls, IgA levels were elevated 5-fold and comprised ∼70% of total Igs. Loop piglets also had reduced serum IgA levels suggesting the source of serum IgA had been interrupted. The isotype profile for loop contents was intermediate between that in the IL of GF and probiotic controls. Surprisingly, colonization alone did not result in repertoire diversification in the IPP. Rather, colonization promoted pronounced proliferation of fully switched IgA(+)IgM(-) B cells in the IPP that supply early, non-diversified "natural" SIgA antibodies to the gut lumen and a primary IgA response in serum.

Toll-like receptors (TLRs) are key molecular sensors used by the mammalian innate immune system to detect microorganisms. Although TLR functions in colonic immune homeostasis and tolerance to commensal bacteria have been intensively researched, the precise roles of different TLRs in response to pathogen infection in the gut remain elusive. Peyer patches are the major entrance of Salmonella infection and antigen transportation in intestine. Here, we report that, in contrast to TLR5 as a "carrier of Salmonella," TLR11 works as a "blocker of Salmonella" to prevent highly invasive Salmonella from penetrating into the murine Peyer patches and spreading systemically. TLR11 plays an important role in mediating TNF-α induction and systemic inflammation in response to Salmonella infection. Remarkably, in mice lacking TLR11, apparent hemorrhages at Peyer patches are induced by highly invasive Salmonella, a phenotype resembling human Salmonella infection. Therefore, our results indicate a potentially important role for TLR11 in preventing murine intestinal infection and modulating antigen transportation in the gut and imply an important role for various TLRs in cooperation with tight control of pathogens penetrating into Peyer patches. The TLR11 knock-out mouse can serve as a good animal model to study Salmonella infection.

Modulation of host responses is an important strategy by which parasites ensure successful establishment and persistence. Host counteraction against this modulation may be required for the host to develop resistance to infection. In this pilot study, experimental infection of dogs with Echinococcus granulosus induced a strong polarization of the cytokine response towards a Th2 phenotype. Consecutive rounds of infection and cure induced resistance to infection resulting in a dramatically lower parasite burden. Repeatedly-infected resistant dogs also lost immune polarization and developed a balanced Th1/Th2 response. No major differences were observed in the production of regulatory cytokines (IL-10, TGF-β) between dogs with high parasite load and dogs with only few intestinal parasites. These results suggest that E. granulosus-driven immunomodulation contributes to successful infection in the definitive host. This information might be relevant for the development of more effective vaccines against this stage of the parasite.

We show that following oral inoculation, prions bind to ileal Peyer patch and cecal patch microfold cells (M cells) in vivo. Furthermore, we show evidence that the cecum acts a biological sump holding large concentrations of prions for relatively long periods, thus increasing the exposure time of cecal patch M cells. Our results show a critical initial step in the translocation of prions from the intestinal lumen of mammals in vivo, which is a precursor to infection.

Secondary lymphoid organs provide a unique microenvironment for generation of immune responses. Using a cell type–specific conditional knockout approach, we have dissected contributions of tumor necrosis factor (TNF) produced by B cells (B-TNF) or T cells (T-TNF) to the genesis and homeostatic organization of secondary lymphoid organs. In spleen, lymph nodes and Peyer patches, the cellular source of TNF, and its molecular form (soluble versus membrane-bound) appeared distinct. In spleen, in addition to major B-TNF signal, a complementary T-TNF signal contributed to the microstructure. In contrast, B-TNF predominantly controlled the development of follicular dendritic cells and B-cell follicles in Peyer patches. In lymph nodes, cooperation between TNF expressed by B and T cells was necessary for the maintenance of microarchitecture and for generation of an efficient humoral immune response. Unexpectedly, soluble but not membrane TNF expressed by B cells was essential for the organization of the secondary lymphoid organs. Thus, the maintenance of each type of secondary lymphoid organ is orchestrated by distinct contributions of membrane-bound and soluble TNF produced by B and T lymphocytes.

Aim This study investigated changes in the mucosal barrier of transplanted intestines with particular emphasis on antigen sampling by Peyer's patches (PPs). Methods Heterotopic small bowel transplantation (SBTx) was performed as described previously. C57BL/6 mice were used as donors and BALB/c (allogeneic) or C57BL/6 mice (syngeneic) as recipients. Tacrolimus (FK506) or saline control was administered to the recipients for 2 weeks. Four groups included in this study were: syngeneic with or without immunosuppression (SYN and SYN + FK506, respectively) and allogeneic with or without immunosuppression (ALLO and ALLO + FK506, respectively). Animals were sacrificed weekly after SBTx to evaluate microfold (M) cells within PPs and for routine histology. By the third postoperative week, recipients were subjected to an intestine loop model to examine the uptake of microbeads by M cells as well as expression of Toll-like receptor 2 (TLR2) protein in the PPs with or without a TLR2 agonist challenge. We also measured occludin expression on follicle-associated epithelium (FAE) of PPs in the grafts. Results Transportation of microbeads through the PPs of the grafts increased in the ALLO + FK506 group compared with that in the SYN or SYN + FK506 group. This finding was accompanied by increased expression of TLR2 in the PPs and a gradually increased number of M cells following SBTx. However, occludin expression patterns on the FAE of the PPs in the grafts were similar among SYN, SYN + FK506, and ALLO + FK506 groups. Nevertheless, as transportation of microbeads and TLR2 expression in the PPs of the grafts was enhanced once exposed to Pam3Cys-SKKKK, similar results were not seen in the ALLO + FK506 group. Conclusions Our study revealed that the mucosal barrier of intestinal grafts is altered under alloreactivity as evidenced by enhanced antigen sampling. Such a change may provide a pathway for translocation of microorganisms in the lumen.

Helicobacter heilmannii induces gastric lymphoid follicles in mice. However, the pathogenic mechanisms behind the induction of gastric lymphoid follicles by H. heilmannii infection have not been elucidated. The aim of this study was to investigate the roles of Peyer's patches (PP) in H. heilmannii-induced immune responses and the development of gastric lymphoid follicles. C57BL/6J and PP deficient mice were infected with H. heilmannii, and in addition to histological and immunohistological examinations, the expression levels of cytokines and chemokines in gastric mucosa were investigated. Gastric lymphoid follicle formation and the infiltration of dendritic cells, B cells, and helper T cells were milder in the PP-deficient mice 1 month after infection, but they were similar in both types of mice after 3 months. The mRNA expression levels of tumor necrosis factor α and CC chemokine ligand 2 were significantly high in the H. heilmannii-infected groups, and CXC chemokine ligand 13 expression was significantly increased in the infected C57BL/6J wild-type mice 1 month after infection. These results suggest that PP are not essential for the formation and development of gastric lymphoid follicles induced by H. heilmannii infection, although they are involved in the speed of gastric lymphoid follicle formation.

The production of B cells and the primary antibody repertoire in mammalian species other than rodents or man appears to depend on gut-associated lymphoid tissue. Bovine B cells are generated in ileal Peyer's patch from late gestational to juvenile age. However, little is known about where and when the bona fide B lymphopoiesis takes place. We analyzed bovine fetuses for signs of ongoing B lymphopoiesis using a combination of immunohistochemistry, flow cytometry, real-time quantitative PCR and RNA in situ hybridization. In fetal bone marrow and lymph node, we could demonstrate pre-B like cells positive for intracellular Ig mu but negative for membrane IgM. Strong expression of immunoglobulin lambda-like polypeptide 1 and recombination activating genes was also detected in the same tissues. Similar analyses did not reveal pre-B like cells in the corresponding adult tissues. These results suggest that bovine fetal bone marrow and lymph node support B lymphopoiesis via a pre-B cell like stage before and in parallel to the development of the ileal Peyer's patch.

The role of lactic acid bacteria in gut mucosal immunity was investigated by comparing the enhanced effects in the Peyer's patches and spleen of BALB/c mice fed daily with Lactobacillus paracasei subsp. paracasei NTU 101 for 3 to 9 weeks. After feeding with Lactobacillus, the percentage of CD4+ T cells in both Peyer's patches and the spleen was significantly increased; however, expression of CD 154 molecules, which play a pivotal role in cell-to-cell communication, on CD4+ T cells and the percentage of B220+ B cells increased only in Peyer's patches. Compared with systemic serum IgA, Peyer's patch-derived immunomodulation induced higher levels of intestinal IgA+-producing cells in the lamina propria. Our data also showed that feeding with Lactobacillus induced stronger CD4+ T cell-dendritic cell interaction, enhanced CD4+ T cell and B cell proliferation, and increased IL-1beta, IL-10, IL-12, IFN-gamma, and TNF-alpha mRNA expression in Peyer's patches, but not in the spleen. Here, we demonstrate that following Lactobacillus treatment, Peyer's patches exhibited a more distinct capacity to induce CD4+ T cell-dendritic cell interactions, lymphocyte proliferation, and cytokine secretion than the spleen, and thereby promoted greater intestinal IgA production that could enhance immunosurveillance to prevent intestinal infections or other intestinal pathologies.

The epithelial barrier of the intestine and the gut-associated lymphoid tissue (GALT) protects the host against luminal pathogenic micro-organisms. This is important at weaning, when animals are exposed to infectious agents and stresses. We have developed a rat model of intestinal inflammation post weaning, based on the systemic administration ofStaphylococcus aureusenterotoxin B (SEB). Since the inflammatory response obtained is mild, the food intake pattern is not affected, which makes this model useful for studies of nutritional therapies for intestinal inflammatory disease. SEB increased T-lymphocytes in Peyer's patches and the number of activated T-lymphocytes in mesenteric lymph nodes (organized GALT). In the lamina propria, SEB increased activated T-lymphocytes as well as cytotoxic and natural killer-cell populations of the diffuse GALT. It also increased pro-inflammatory cytokines and inflammatory mediators in both Peyer's patches and mucosa. Rats given SEB had higher paracellular permeability to macromolecules, which was associated with a reduction in epithelial tightness. This model was used to examine whether dietary supplementation with spray-dried animal plasma proteins affects intestinal inflammation. Results showed that dietary plasma proteins can attenuate the mucosal immune response in both organized and diffuse GALT and that these effects are mediated by a reduction in the production of pro-inflammatory cytokines.

The pharmacological mechanism of drug pair of astragali and cinnamon in shiquan dabu decoction were studied in blood deficiency and Qi deficiency modeled mice. In Qi deficiency, the drug pair of astragali and cinnamon in shiquan dabu decoction had the ability of improving the number of white blood cells and peyer patches, and T cell activity. It had no action in red blood cell number and phagocytic activity of peritoneal macrophage, and B cell activity. In blood deficiency, the drug pair of astragali and cinnamon in shiquan dabu decoction had the effect of improving the hemoglobin content and T cell activity. It did not affect the number of white blood cells and peyer patches, phagocytic activity of peritoneal macrophage and B cell activity. In conclusion, the drug pair of astragali and cinnamon in shiquan dabu decoction has different actions, the quantity of drug pair in shiquan decoction should be changed according to the symptoms in process of diseases.

Humans have evolved with oral exposure to dietary microparticles and nanoparticles as a normal occurrence but the ever-growing exploitation of nanotechnology is likely to increase exposure further, both qualitatively and quantitatively. Moreover, unlike the situation with respirable particles, relatively little is known about gastrointestinal intake and handling of nanoparticles. With a long term interest in gut exposure and responses to dietary microparticles, our group is now applying its expertise to nanoparticles in the gastrointestinal tract. Here we aim to address (i) the current challenges associated with the characterisation of particle-host or particle-cell interactions, (ii) the origin and mechanisms of uptake of particles in the gastrointestinal tract, especially via the Peyer's patch and (iii) potential cellular effects of nanoparticles in the generation of reactive oxygen species and inflammasome activation, or microparticles in their adjuvant activity in pro-inflammatory signalling and immune responsiveness.

The purpose of this study was to evaluate the possibility of lectin-coupled microspheres to improve the targeted delivery of protein antigens to the lymphoid tissues of mucosal surfaces. Bovine serum albumin containing acid phosphatase model protein and polystyrene microspheres were coupled with mouse M-cell-specific Ulex europaeus lectin. The coupling efficiency, physical characteristics and the binding capabilities of the microspheres to the follicle associated epithelium of the Peyer's patches were evaluated in vitro and ex vivo in mice intestine. The results showed that coupling of lectin to albumin microspheres did not significantly affect the bioactivity of the encapsulated acid phosphatase model protein. It was also shown that there was preferential binding of the lectin-coupled microspheres to the follicle-associated epithelium. It was concluded from the results of the study that coupling of ligands such as lectin specific to cells of the follicle associated epithelium can increase the targeting of encapsulated candidate antigens for delivery to the Peyer's patches of the intestine for improved oral delivery.

The ruminant gut-associated lymphoid tissues are broadly classified into ileal and jejunal Peyer's patches (PP). We isolated single lymphatic follicles from ileal and jejunal PP and examined mRNA expression of 13 cytokines using RT-PCR. Four patterns of differential expression were identified. In Pattern 1, the cytokines IL-7, IL-10, IL-12, and IL-18 were detected in all follicles of both ileal and jejunal PP. In Pattern 2, the cytokines IL-2, IL-4, and IL-13 were expressed in most jejunal PP follicles, but were undetectable in the ileal PP follicles. The cytokines characterizing Pattern 3 (IL-1beta, IFN-gamma, and IL-6) were detected in all follicles of the jejunal PP, but were differentially expressed in each follicle of ileal PP. In Pattern 4, the cytokines IL-8, TNF-alpha, and GM-CSF were variably expressed in follicles of both ileal and jejunal PP. More detailed knowledge about differential expression of cytokines in ileal and jejunal PP will facilitate a better understanding of the immune responses of primary and secondary lymphoid organs in the bovine small intestine.

Ileal Peyer's patches (PPs) are involved early during sheep scrapie infection. This study qualitatively and semi-quantitatively evaluated ileal tract and PP innervation in 29 Sarda ovines of different age, PrP genotype and scrapie status. A prominent network of fibres was detected within PPs, mainly located in interfollicular lymphoid and stromal components. Intrafollicular fibres were rarely observed, with no apparent differences between scrapie-free and scrapie-affected animals, or among ovines carrying different PrP genotypes. In adult sheep, independent of their scrapie status, nerve fibres could be detected infrequently, close to the follicle-associated epithelium. Fibres were also detected within newly formed follicles and intrafollicular microgranulomas.

Most of the immunoglobulin A (IgA) in the gut is generated by B cells in the germinal centers of Peyer's patches through a process that requires the presence of CD4 + follicular B helper T(T FH ) cells. The nature of these T FH cells in Peyer's patches has been elusive. Here, we demonstrate that suppressive Foxp3 + CD4 + T cells can differentiate into T FH cells in mouse Peyer's patches. The conversion of Foxp3 + T cells into T FH cells requires the loss of Foxp3 expression and subsequent interaction with B cells. Thus, environmental cues present in gut Peyer's patches promote the selective differentiation of distinct helper T cell subsets, such as T FH cells.

OBJECTIVE: In present study, feeding effect of probiotic dahi containing Lactobacillus casei on immune system in terms of cytokine gene expression in the spleen and Peyer's patches of mice was evaluated. METHODS: Animals were divided into three groups and fed with; synthetic diet [control group (CD)], dahi containing mixed dahi culture [control dahi-fed group (CDF)]; and probiotic dahi fed group (PDF) for 28 days. The mRNA levels of IL-2, IL-4, IL-6 and IFN-γ were examined after 14 and 28 days. Total lactobacilli and lactococci counts were determined in the feces. RESULTS: The mRNA levels of IFN-γ in both spleen and Peyer's patches was found to be significantly increased in PDF animals after 14 and 28 days (P

Recurrent Crohn's disease originates with small erosions in the follicle-associated epithelium overlying the Peyer's patches. Animal studies have illustrated mucosal immune regulation by dendritic cells located in the subepithelial dome. The aim of this study was to characterize the dendritic cells at this specific site in patients with Crohn's disease. Ileal tissues were obtained after surgery performed on Crohn's patients; ileal samples from noninflammatory bowel disease and ulcerative colitis served as standard and inflammatory controls, respectively. Flow cytometry of isolated intestinal mononuclear cells showed a larger subset of dendritic cells in Crohn's samples compared with controls. This finding was corroborated by confocal microscopy, showing enhanced infiltrates of cells positive for the dendritic cell markers, DC-SIGN(+) and CD83(+), in the subepithelial dome. Moreover, the CD83(+) cells in Crohn's tissues showed reduced expression of the lymph node migratory receptor, CCR7, possibly contributing to the high numbers of dendritic cells. After exposure to nonpathogenic Escherichia coli in Ussing chambers, dendritic cells in the subepithelial dome of Crohn's disease demonstrated increased co-localization with translocated bacteria. Immunohistochemical results revealed that DC-SIGN(+) cells in Crohn's tissues were found to express toll-like receptor 4 and produce tumor necrosis factor-alpha. In conclusion, nonmigrating dendritic cells that accumulate in the subepithelial dome and internalize nonpathogenic bacteria may be important for the onset and perpetuation of mucosal inflammation in Crohn's disease.

In contrast to our understanding of murine lymphoid organogenesis, detailed knowledge on the mechanisms of human lymph node development is virtually lacking. This is mainly due to the obvious difficulties that accompany research using human fetal organs. In this review we will highlight current knowledge on human lymph node and Peyer's patch development and will temporally align observations made in humans with data available from murine studies. In the final paragraphs we will put this knowledge in the context of human malignancies in which interactions between lymphocytes and stroma, resembling those seen in lymphoid organs, are recapitulated. (c) 2008 Elsevier Ltd. All rights reserved.

Peyer's patches of the small intestine serve as inductive sites for mucosal immunity as well as targets for invasive enteropathogens, including Salmonella. Because they are innervated by catecholamine-containing enteric nerves, the hypothesis that the endogenous catecholamines dopamine and norepinephrine or sympathomimetic drugs alter Salmonella Typhimurium uptake into Peyer's patches was tested. Porcine jejunal Peyer's patch explants were mounted in Ussing chambers and inoculated with a porcine field isolate of Salmonella Typhimurium DT104. Salmonella recovery from gentamicin-treated tissues increased significantly between 30 and 90 min of bacterial exposure to the mucosal surface. Addition of the neuronal conduction blocker saxitoxin (0.1 micromol L(-1)) or dopamine (30 micromol L(-1)) to the contraluminal aspect of explants decreased bacterial recovery after 60 min of Salmonella exposure. The effects of dopamine were mimicked by cocaine and methamphetamine (30 micromol L(-1)), which act on catecholaminergic nerve terminals to increase synaptic neurotransmitter concentrations. These results suggest that enteric catecholaminergic nerves modulate Salmonella colonization of Peyer's patches at the earliest stages of infection, in part by altering epithelial uptake of bacteria.

Normal organogenesis requires co-ordinate development and interaction of multiple cell types, and is seemingly governed by tissue specific factors. Lymphoid organogenesis during embryonic life is dependent on molecules the temporal expression of which is tightly regulated. During this process, haematopoietic 'inducer' cells interact with stromal 'organizer' cells, giving rise to the lymphoid organ primordia. Here we show that the haematopoietic cells in the gut exhibit a random pattern of motility before aggregation into the primordia of Peyer's patches, a major component of the gut-associated lymphoid tissue. We further show that a CD45+CD4-CD3-Il7Ralpha-c-Kit+CD11c+ haematopoietic population expressing lymphotoxin has an important role in the formation of Peyer's patches. A subset of these cells expresses the receptor tyrosine kinase RET, which is essential for mammalian enteric nervous system formation. We demonstrate that RET signalling is also crucial for Peyer's patch formation. Functional genetic analysis revealed that Gfra3-deficiency results in impairment of Peyer's patch development, suggesting that the signalling axis RET/GFRalpha3/ARTN is involved in this process. To support this hypothesis, we show that the RET ligand ARTN is a strong attractant of gut haematopoietic cells, inducing the formation of ectopic Peyer's patch-like structures. Our work strongly suggests that the RET signalling pathway, by regulating the development of both the nervous and lymphoid system in the gut, has a key role in the molecular mechanisms that orchestrate intestine organogenesis.

The effects of cyclosporin A (CY) and cyclophosphamide (CPS) on Peyer's patches (PP) were studied in Wistar rats, exposed in utero and neonatally or during adult age. In one study, pregnant dams received 5 or 15 mg/kg bw/day CY from gestation day 6 to day 21 of lactation. In two other studies, animals were exposed at young adult age: female rats received orally 5 or 20 mg/kg/day CY or 5 or 10 mg/kg bw CPS for 4 weeks; males received orally 5 mg/kg bw CPS for 4 weeks, or a single iv injection of 50 mg/kg bw CPS. Upon in utero and neonatal exposure, the numbers of grossly observed PP were increased in male pups from the high-dose CY dams at 70 days of age. Exposure to high-dose CY at adult age only tended to decrease the numbers of PP; germinal center development was reduced in the PP from the middle segment of the small intestines, as examined microscopically. Exposure to both doses CPS at adult age reduced the numbers of PP and reduced germinal centre development and the number of lymphocytes in all compartments of PP. It was concluded that the effects of CPS and CY could be established by counting the number of grossly visible PP and by microscopic observation of PP, provided that regional differences of PP were taken into account. Moreover, the type of effects of an immunotoxic agent may vary with age of exposure. Copyright © by the Society of Toxicologic Pathology.

Other factors than the allergen itself may be of importance in the development of food allergy. This report describes the influence of the immunosuppressive compound bis(tributyltin)oxide (TBTO), present in the food chain, on the development of food allergy to peanut or ovalbumin in Brown Norway (BN) rats. To study these effects BN rats were sensitized to either 1 or 10 mg peanut or ovalbumin by daily oral gavage and the TBTO-groups were fed a diet containing 80 mg TBTO per kg diet. Co-exposure to TBTO not only resulted in decreased general immunologic parameters such as weights of mesenteric lymph nodes and Peyer's patches, lymphocyte proliferation rates in splenocytes, but also on allergic parameters. In the peanut allergen-model TBTO decreased allergen-specific Th2 cytokine production by spleen cells, number of eosinophilic and basophilic granulocytes in the blood and production of mast cell protease II after oral food challenge. In the ovalbumin allergen-model TBTO decreased the number of eosinophilic and basophilic granulocytes, allergen-specific IgE and production of mast cell protease II after oral food challenge. The data imply that in the process of risk assessment of food allergy attention should be given to immunomodulating compounds present in the diet. © 2007 Elsevier Ireland Ltd. All rights reserved.

The aim of the present study was to evaluate the utility of pullulan acetate microparticles (PAMs), chitosan micropaticles (CMs), and dipalmitoylphosphatidyl-serine-liposomes (PS-Lip) as oral carriers for delivery to the intestinal Peyer's patches (PPs). To monitor PP delivery after oral administration, PAMs, CMs, and PS-Lip were radiolabeled with 99mTc. Radiolabeling efficiencies of the particles were 95±2.5% (PAMs), 87±4.3% (CMs), and 77.2±5.8% (PS-Lip). In delivery studies to the PPs, the percentage of PS-Lip taken up to the PPs was 3.8 × 10−3±0.3% of the administered dose with PS-Lip group showed significantly high uptake compared to the PAM and CM groups. These results suggest that PS-Lip may be used as a potential system for developing an oral delivery carrier. Drug Dev. Res. 67:884–889, 2006. © 2007 Wiley-Liss, Inc.

The expression level of normal cellular prion protein (PrPC) is thought to influence the transmission of transmissible spongiform encephalopathies (TSEs) from the peripheral entry site to the site of pathological changes in the central nervous system. In many TSEs, the clinical disease is preceded by a period in which the agent accumulates in lymphoid organs, particularly in association with follicular dendritic cells of lymphoid follicles. As the probable route of entry of the TSE agent is via the gut, the expression profile of PrP was examined in well-developed gut-associated lymphoid tissue of lambs, the ileal Peyer's patch, by laser microdissection and real-time RT-PCR. Lymphoid follicles were found to have very low levels of expression, whilst highest levels were detected in the outer submucosa and the muscular layer. These findings were supported by in situ hybridization and immunohistochemistry, which showed specific labelling in nerve cells in ganglia of the submucosal (Meissner's) and myenteric (Auerbach's) plexi of the enteric nervous system. Based on the assumption that potential sites for conversion to the scrapie-related prion protein (PrPSc) should display high levels of expression of PrPC, this study suggests that the accumulation of PrPSc in the lymphoid follicles of the Peyer's patch is not preceded by PrP conversion in the same tissue compartment.

The design of particulate vaccine delivery systems, particularly for mucosal surfaces, has been a focus of interest in recent years. In this context, we have previously described the development and the characterization of a new nanosized delivery system, consisting of a model antigen adsorbed to chitosan particles and coated with sodium alginate. In the present work the ovalbumin release profiles from these coated nanoparticles in different pH buffers were investigated and compared to those of the uncoated particles. Cytotoxicity of the polymers and nanoparticles was assessed using the MTT assay. Finally, particle uptake studies in rat Peyer's patches were performed. It was demonstrated that the coating of the nanoparticles with sodium alginate not only avoided a burst release observed with uncoated particles but also increased the stability of the particles at pH 6.8 and 7.4 at 37 °C. At neutral pH, the release was lower than 5% after 3.5 h incubation in a low ionic strength buffer. For both, chitosan and alginate polymers, and for the nanoparticles, comparable cell viability data close to 100%, were obtained. Additionally, based on confocal laser scanning microscopy observations, it was shown that alginate coated nanoparticles were able to be taken up by rat Peyer's patches, rendering them suitable carriers for intestinal mucosal vaccination. http://www.sciencedirect.com/science/article/B6T3D-4K6CHRP-1/1/a257a285900ecde6d4747e1df67e1a82

A recently developed oral immunisation model in pigs in which F4 (K88) fimbriae of enterotoxigenic Escherichia coli are administered to induce a protective intestinal immunity, was used to determine the optimal inductive sites of the F4-specific intestinal immune response. Hereto, pigs were immunised with F4 orally, in the lumen of the mid-jejunum, ileum or mid-colon. Throughout the small intestine, the highest number of ASC was found following jejunal immunisation, followed by ileal, oral and colonic immunisation. To determine the signifance of Peyer's patches in the induced immune response, F4 was injected into the jejunal Peyer's patches (JPP), lamina propria (LP) and ileal Peyer's patches (IPP). Immunisation in the JPP induced the highest number ASC in the small intestine, whereas immunisation in the LP and IPP resulted in lower intestinal antibody responses. In conclusion, we have shown that the JPP are the major inductive sites of the F4-specific intestinal antibody response. This knowledge could be important when using the pig as an animal model for vaccination studies.

Starch microparticles, an effective adjuvant for oral vaccination in mice, are taken up over the follicle-associated epithelium (FAE) in Peyer's patches when human serum albumin is conjugated to the particles (HSAmp). When recombinant cholera toxin B subunit (rCTBmp) is conjugated, they are taken up over both the FAE and the villus epithelium. This study investigated the effects of the different targeting on the immune response by using particles with both HSA and rCTB (HSA/rCTBmp). The response induced after oral immunisation with this formulation in mice was compared with that obtained after administration of HSAmp, rCTBmp or both given concomitantly (HSAmp + rCTBmp) and after subcutaneous administration. Both the HSA- and rCTB-specific responses were followed quantitatively (as assessed by the anti-[IgM + IgG] level, the s-IgA response and the delayed-type hypersensitivity [DTH] response), or qualitatively (by the IgG subclass profile). After subcutaneous administration, the rCTB-specific IgM + IgG and DTH responses were lower after HSA/rCTBmp than after rCTBmp and the HSA-specific subclass ratio (IgG1/IgG2a + IgG2b) was lower with HSAmp + rCTBmp (but not with HSA/rCTBmp) compared to HSAmp. However, no quantitative and qualitative differences in the immune response after oral administration were detected when rCTB was added to HSAmp. The results indicate that only the uptake over the Peyer's patches decides the immune responses after oral administration and that the increased targeting to GM1 receptors of the villus epithelium does not affect the immune response. Moreover, the qualitative Th1/Th2-balance is controlled by the inherent properties of the antigens in the microparticles upon subcutaneous administration. Thus, the obtained information is important for designing oral microparticulate vaccines in order to obtain the wanted immune response.

Peyer's patches constitute both an inductive immune site and an enteropathogen invasion route. Peyer's patch mucosae from porcine jejunum were mounted in Ussing chambers, and either Salmonella choleraesuis vaccine strain SC-54 or non-pathogenic rodent and porcine Escherichia coli strains contacted the Peyer's patch mucosa for 90 min. Internalized bacteria were quantified by a gentamicin resistance assay. Monodansylcadaverine (300 microM, luminal addition), an inhibitor of clathrin-mediated endocytosis, significantly inhibited internalization of both E. coli strains relative to tissues untreated with the inhibitor; internalization of SC-54 was unaffected. The actin-disrupting agent cytochalasin D (10 microM, luminal addition), inhibited internalization of pig-adapted E. coli but not that of rodent-adapted E. coli or SC-54. Internalization of SC-54 and non-pathogenic E. coli in Peyer's patches appears to occur through different cellular routes.

Triptolide is a purified component from a traditional Chinese herb Tripterygium wilfordii Hook F. It has been shown to have anti-inflammatory and immunosuppressive activities by its inhibitory effect on T cells. But the effect of triptolide on Peyer's patch cells is unknown. Enteric mucosal immune system, including Peyer's patch, is regarded as one of the sites for inducing immunity tolerance, and this intolerance effect has been used to induce oral tolerance which can considerably reduce arthritis severity in several models of experimental polyarthritis and RA patients. In this study, we investigated the effect of triptolide on the Peyer's patch cells and peripheral lymphocytes in collagen induced arthritis (CIA) in rats. CIA in rat is a widely studied animal model of inflammatory polyarthritis with similarities to rheumatoid arthritis (RA). Our data show that triptolide could lower the arthritic scores and delay the onset of CIA. There are more Peyer's patches in triptolide treated rats than in control rats, while there is no difference in Peyer's patch numbers between CIA rats and triptolide treated rats. In the Peyer's patch, more CD4+ cells are observed in CIA rats, and the numbers of CD4+ cells in triptolide treated rats and control rats are similar. While more CD8+ cells are observed in triptolide treated rats, and the numbers of CD8+ cells in CIA rats and control rats are similar. In periphery, more CD4+ cells and less CD4+ cells in CIA rats and triptolide treated rats are respectively observed. Therefore, the regulation on Peyer's patch might explain some of the immunosuppressive activities of triptolide, and enteric immune response might be actively involved in CIA pathogenesis. It is suggested that the Peyer's patch is one of the primary targets of the immunosuppressive activity of triptolide.

Background and aims: Surgical management of extrahepatic cholestasis is frequently complicated by bacterial translocation and severe liver injury. The aim of this study was to clarify the involvement of Toll-like receptors (TLRs) in the pathogenesis of bacterial translocation and liver injury in obstructive cholestasis. Methods: TLR2 deficient (TLR2 −/− ), MyD88 −/− , Jα281 −/− , gld / gld , and lpr / lpr mice, all of which have a C57BL/6 background, and C3H/HeN and TLR4 mutated C3H/HeJ mice were subjected to bile duct ligation (BDL). Faecal IgA and serum alanine aminotransferase levels were determined after BDL. Apoptosis was examined by histological and flow cytometric analyses of cells from Peyer’s patches and the liver. Results: The size and number of B cells in Peyer’s patches markedly decreased on day 3 after BDL. Increased apoptosis in Peyer’s patch B cells was evident on day 1 after BDL in control mice but not in lpr / lpr , MyD88 −/− , or C3H/HeJ mice. On the other hand, TLR2 and Fas ligand expression on intrahepatic NK1.1 + T cells increased on day 1 after BDL in C57BL/6 mice. Liver injury and apoptosis were evident on day 1 after BDL in control and C3H/HeJ mice but were significantly reduced in TLR2 −/− , Jα281 −/− , gld / gld , and lpr / lpr mice. Conclusions: TLR4 and TLR2 may play important roles in Fas dependent apoptosis in Peyer’s patch B cells and hepatocytes, respectively, at an early stage after BDL in mice.

Critical assessment of intestinal immune responses requires the ability to characterize leukocytes from different anatomic locations as leukocytes from inductive sites such as Peyer's patches and lymphoid follicles vary significantly from their effector counterparts, intraepithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL). This study describes (1) methods developed to isolate specific intestinal leukocyte populations with high yield and purity, (2) difficulties encountered in establishing a panel of monoclonal antibodies to assess phenotype, and (3) the phenotypic characterization of effector and inductive sites in the feline small intestine. We found that the phenotypic distribution of feline intestinal leukocytes was similar to that found in other species such as humans, macaques and mice. The majority of IEL were CD5(+) T-cells with less than 7% B-cells. CD8(+) T-cells comprised approximately 60% of the IEL with roughly half displaying CD8alphaalpha homodimers. Approximately 10% of IEL were CD4(+) T-cells. In the LPL, CD4(+) T-cells predominated at 42%, with 33% CD8(+) T-cells and 10% B-cells. As would be expected, B-cells predominated in Peyer's patches with 40% B-cells, 28% CD4(+) T-cells and 20% CD8(+) T-cells. Increased MHCII expression was found in the Peyer's patches as compared to the IEL and LPL. B7.1 expression was significantly higher in mucosal leukocyte populations as compared to organized lymphoid tissue in the periphery with expression detected on 65% of IEL and 53% of LPL. Plasma cells were found in all regions of small intestine examined with greater numbers in lamina propria and Peyer's patches. Lymphoblasts were only identified in inductive tissue. In general, no differences were found between the phenotype of mucosal leukocyte populations from specific pathogen free or random source cats. However, the percentage of CD4(+) CD25(+) T-cells was significantly greater in both IEL and LPL from random source animals. This study provides techniques and a baseline from which future studies of the feline intestinal immune system can be conducted.

Fluorescence imaging technology can be applied to many aspects of cell biology ranging from the analysis of specific markers in cells and tissues to the biological actions and distribution of fluorescent proteins or particles in living cells. In this review, we examine the role of fluorescence imaging, in conjunction with other microscopical techniques, to study sites of uptake of material across the gastrointestinal epithelium. We will focus primarily on intestinal M cells, specialised antigen-sampling cells in the epithelium of the gut-associated lymphoid tissue (GALT), including Peyer's patches. In addition to their importance as sites for uptake of inert material, and hence their potential as a route of delivery of vaccines, etc., M cells are also a major site of infection by a range of microbial pathogens. The application of new fluorescence imaging technologies has expanded our knowledge on the structure, development and function of these fascinating cells.

Membranous (M) cells are specialized epithelial cells of the Peyer's patches that sample antigens from the gut lumen, thereby enabling the host to respond immunologically. Recent studies suggest that this transport can be up-regulated within hours by de novo formation of M cells from enterocytes. To test this hypothesis, we used an in vivo model and induced the transcytosis of tracers in Peyer's patches by application of Streptococcus pneumoniae R36a into the gut lumen. Using cell-type-specific markers, we quantified M cells in the Peyer's patch domes, lymphocytes associated with M cells, and the transport rate for experimentally applied microbeads after 3 hours of exposure to R36a. The transport of latex microbeads was significantly increased by +131% in the R36a-treated patches as compared to buffer controls (P < 0.001). While in controls, each M cell was associated with 2.05 +/- 0.64 lymphocytes, a significant increase (+55.1%; P < 0.001) was determined in the R36a-treated patches. However, no statistical difference was detected in the percentage of M cells in the dome epithelia (46.0 +/- 4.6% versus 45.5 +/- 3.8%). It is concluded that bacteria-induced up-regulation of particle transport in Peyer's patch domes is due to an increased transport rate of the M cells, but not to a de novo formation of M cells. The data support the hypothesis that M cells represent a separate cell lineage that does not derive from enterocytes on the domes.

OBJETIVOS: O propósito deste estudo foi analisar experimentalmente a eficiência da suplementação alimentar da dieta do Município de Quissamã, RJ, em recuperar a desnutrição durante o período de crescimento. MÉTODOS: Foram utilizados 42 Rattus norvegicus, desmamados ao 26º dia e induzidos à desnutrição por 21 dias (ração hipoprotéica 2%, ad libitum). Os animais foram distribuídos em sete grupos, alimentados com suas respectivas dietas, todas isoprotéicas (10%) e isoenergéticas (350Kcal/100g). Foi registrado o peso dos animais e, após o sacrifício, foram coletados e pesados fígado, rins, baço e intestino. RESULTADOS: O ganho ponderal médio no 28º dia do controle suplemento alimentar (75,33g) foi significativamente inferior aos demais grupos, e o do controle suplemento alimentar e vitaminas+minerais foi o mais elevado (213,17). Quase todos os grupos diferenciaram-se estatisticamente no peso médio de fígado, rins e baço; os órgãos do controle suplemento alimentar apresentaram o menor peso (respectivamente 3,34g; 0,97g; 0,24g) sendo significativamente inferior aos demais grupos. O controle suplemento alimentar e vitaminas+minerais apresentou o maior peso médio do fígado (13,85g). O Controle vitaminas+minerais apresentou o maior peso médio dos rins (1,88g) e do baço (0,87g). O número de placas de Peyer/animal variou de nove a treze, sem diferenças entre os grupos; o tamanho das placas de Peyer do controle suplemento alimentar (2,6mm) foi significativamente inferior aos demais grupos. O Quissamã suplemento alimentar apresentou as maiores placas de Peyer (4,4mm). O controle suplemento alimentar apresentou sempre valores inferiores para todos os parâmetros estudados comparativamente, já que não foram adicionados à sua ração vitaminas e minerais. CONCLUSÃO: A dieta de Quissamã, RJ experimentalmente alcança as necessidades mínimas para promover a recuperação da desnutrição, sendo desnecessária a adição de vitaminas e minerais e/ou suplemento alimentar.

Summary Child mortality in diarrhoeal disease is increased significantly by vitamin A deficiency in poor countries. The pathological mechanisms are not known in detail. However, in this paper we report that vitamin A-deficient Wistar rats had much reduced IgA+ plasma cells in the ileal lamina propria (eightfold reduction from 470 cells/mm2, P = 0·009), as well as a prominent reduction of CD4+ cells in the parafollicular regions of ileal Peyer's patches (reduction from 7200 to 105 cells/mm2, P = 0·009). IL-2Ralpha-chain (CD25) positive lymphocytes in the ileal Peyer's patches were also reduced significantly in vitamin A deficiency (from 1400 to 300 cells/mm2, P = 0·009). The density of CD8 cells tended to be increased relative to the control animals (from 5100 to 6000 cells/mm2, not statistically significant). In conclusion, the marked decrease of lamina propria IgA+ plasma cells may be one cause of the high diarrhoeal mortality in vitamin A deficiency. This, in turn, appears to be related to reduced numbers of activated or regulatory CD4+ T cells in Peyer's patches.

Excised porcine intestinal tissue obtained from the local abattoir was studied for its suitability to examine the uptake and transport of poly(lactic-co-glycolic acid) (PLGA) nanoparticles in Peyer's (PP) and non-Peyer's patch (NPP) tissue in vitro. Incubation of such tissue with fluorescent PLGA and polystyrene particles revealed negligible uptake into the intercellular space with no noticeable difference between PP and NPP tissue. Similarly, yeast cells, which were used as a positive control for selective uptake into PP tissue, were found in the subepithelial area of both PP and NPP tissue. Therefore we examined the morphological integrity of the tissue for the duration of the experiments. For this purpose, excised intestinal tissue from the abattoir transported to the laboratory was examined for morphological changes by light microscopy and compared to intestinal tissue from freshly slaughtered piglets. Already after 25 min postmortem, we observed lysis and defoliation of the epithelial cell layer followed by a complete loss of villus architecture and, consequently, resulting in a complete loss of the integrity of the intestinal tissue. This may explain the limited and non-selective particle uptake when using excised intestinal tissue from the abattoir. It is suggested to avoid small intestine obtained from the abattoir and to use tissue from freshly sacrificed animals within a few minutes postmortem. Experiments should then be performed under adequate oxygenation of the excised intestinal tissue.

ICR:CD-1 male mice were orally administered with Nivalenol(NIV) at the dose levels of 5, 10 and 15 mg/kg body weight, and examined at 12, 24 and 48 hours after inoculation (HAI), respectively, to elucidate the process of development of apoptosis in the thymus, spleen and Peyer's patch. There were no signs of clinical disorders and no changes in body and organ weights until 48 HAI except for that the thymus weight significantly decreased at 48 HAI. Immunohistochemically, the number of apoptotic lymphocytes evaluated by in situ detection for fragmented DNA showed a dose-dependent increase at 12 HAI in both the thymus and the Peyer's patch, while it became to increase at 24 HAI in the spleen. Dead lymphocytes in the thymus, spleen and Peyer's patch showed ultrastructural characteristics of apoptosis. Moreover, the DNA ladder was first detected by agarose gel electrophoresis at 12 HAI in the thymus of 15 mg/kg-group. The results clearly indicate that NIV is able to induce apoptosis in the lymphoid tissues of mice.