Peyer's Patch Cells Research Articles

Effects of oral administration of Butyrivibrio fibrisolvens MDT-1 on the development and healing of atopic dermatitis in NC/Nga mice

The purpose of this study was to evaluate the effects of oral administration of Butyrivibrio fibrisolvens MDT-1 (MDT-1) on mite antigen-induced atopic dermatitis (AD) in NC/Nga mice. When administration of the freeze-dried cells of MDT-1 was initiated one week before mite-antigen swabbing, the development of AD-like skin lesions was alleviated. The cell homogenate and membrane fraction had similar effects, showing that cell components are effective. Freeze-dried cells were found to be replaceable by the crude lipopolysaccharide extracted from MDT-1. Alleviation of AD was concomitant with a decrease in the serum IgE level. Determination of cytokines produced by Peyer's patch cells showed that MDT-1 administration increased IL-12, tended to increase IFN-γ, and tended to decrease IL-10, but did not affect IL-4. When MDT-1 was administered after the skin lesions had progressed, the symptoms were ameliorated, suggesting that MDT-1 has AD-healing effects. MDT-1 was as effective as prednisolone, but different from prednisolone in that MDT-1 showed no detectable side effects such as body weight loss. We previously reported that MDT-1 administration prevented and alleviated colorectal cancer, sarcoma, and enterocolitis in mice. Taken together, MDT-1 might be beneficial for maintaining the health of pet animals and humans.

Immunomodulatory Properties of Highly Viscous Polysaccharide Extract from the Gagome Alga (Kjellmaniella crassifolia).

Marine brown algae are rich in sulfated polysaccharides, which have the ability to form gels and viscous solution. Sulfated polysaccharides exhibit many biological activities; however, little is known whether the viscoelastic property in the polysaccharide extract is correlated with biological activities. We examined the immunomodulatory properties of highly viscous polysaccharide extract (HVPE) from Gagome Kjellmaniella crassifolia in a murine model, and the effects were compared with those of a less viscous polysaccharide extract (LVPE). HVPE or LVPE (10, 30, and 100mg/kg/day) were orally administered to C57BL/6 mice for 14days. Secretions of cytokine and IgA in Con A-stimulated spleen and Peyer's patch (PP) cells and phagocytic activity of peritoneal macrophages was determined. IFN-γ, IL-12, IL-6, and IgA secretions showed high levels in spleen cell cultures from mice administered HVPE, whereas these effects were diminished in the LVPE-administered mice. The phagocytic activity of peritoneal macrophages was enhanced by the continuous oral administration of HVPE, and these effects were higher than those of LVPE. Furthermore, an increase in IgA secretion by administration of HVPE was observed in Con A-stimulated PP cells. These results suggest that the polysaccharide extract from K. crassifolia has immunomodulatory activities, which depend on the viscosity.

Garlic extract and its selected organosulphur constituents promote ileal immune responses ex vivo

The effects of garlic extract and three organosulphur compounds of garlic on intestinal immune responses in mice were investigated. Peyer’s patch (PP) cells were isolated from mice orally administered with garlic extracts or one of three organosulphur compounds (alliin, allicin, diallyl disulphide (DADS)). PP cells isolated from mice that had been orally injected with ethanol extract significantly produced interferon (IFN)-γ and interleukin (IL)-4. IL-2 production in PP cells was significantly reduced by hot-water and ethanol extracts from garlic. PP cells from mice administered with two organosulphur compounds, alliin or DADS (5mg/kg/day), could produce IL-2, IFN-γ and IL-4, whereas allicin showed moderate activity. The enhancement activity of IL-2 and IFN-γ productions in PP cells by DADS was higher than those obtained by administration of alliin or allicin. Comprehensive analyses of genetic profiles in PP tissue from mice administered with ethanolic extracts, allicin or alliin revealed that oral administration of samples increased 68–144 genes and decreased 50–52 genes by ⩾1.8-fold. Analyses of clustering profiles of microarrays indicated that ethanol extract and alliin upregulated the expression of IFN-γ. These data showed that garlic and its organosulphur compounds stimulate de novo IFN-γ biosynthesis in PP cells, thereby promoting ileal immune responses.

INTESTINAL IMMUNE SYSTEM-MODULATING ACTIVITY THROUGH PEYER'S PATCH OF FLAVONOID GLYCOSIDE PURIFIED FROMCITRUS UNSHIUPEEL

After methanol extract (CUP-2) with intestinal immune system-modulating activity through Peyer's patch was prepared from Citrus unshiu peel, CUP-2C-2–2 was purified by solvent partitioning, silica gel 60 and Sephadex LH-20 chromatographies (Pharmacia Biotech, Uppsala, Sweden). Ultraviolet-visible spectral, 1H/13C-NMR, and fast atom bombardment mass spectrometry analyses suggested that CUP-2C-2–2 was identified to flavonoid glycoside (5,7,3′,4′-tetrahydroxyflavone linked by glucose) with molecular weight of 725 Da. When the active chloroform layer (CUP-2C) fractionated from CUP-2 was orally administered in mice, the potent activity was observed on the fifth day of 2.0 g/kg body weight/day (1.59-fold of the saline control). Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-6 contents in the culture medium of Peyer's patch cell were also significantly increased (1.80- and 2.20-fold, respectively) compared with the saline control. These results suggested that flavonoid glycoside from C. unshiu peel might stimulate Peyer's patch and produce the multifunctional hematopoietic growth factors such as GM-CSF and IL-6 followed by proliferation of bone marrow cells. PRACTICAL APPLICATIONS C. unshiu peel is widely used as the traditional herbal prescription or tea in East Asia. Since the early 1980s, many researchers have been studying the physiologically active substances from citrus fruit peel for the purpose of exploring their more valuable utilization. Current work is focused on low-molecular-weight constituents with intestinal immune system modulating activity through Peyer's patch from citrus peel. It is clearly shown that the purified active substance (CUP-2C-2–2) is characterized as flavonoid glycoside. When the active fraction (CUP-2C) was orally administered in mice, production of hematopoietic growth factors from Peyer's patch cells was stimulated and proliferation of bone marrow cells was induced by these growth factors influxed via systemic circulation. This conclusion supports the rationality of citrus peels as a potential source of biological response modifier for food supplementation or functional foods.

Influence of peroral application of a herbal immunomodulator on the antibody production of Peyer's patches cells.

The influence of the peroral administration of the macromolecular components of a herbal immunomodulator isolated from an aqueous-ethanolic extract of the mixed herbal drugs Thujae summitates, Baptisiae tinctoriae radix, Echinaceae purpureae radix and Echinaceae pallidae radix on the function of Peyer's patches cells was investigated in mice. Peyer's patches cells isolated from mice which had received oral administration of the macromolecular fraction of the plant extract developed a significantly enhanced plaque-forming cell (PFC) response to sheep red blood cells after incubation with these cells in the presence of lipopolysaccharide or the extract fraction for 7 days in vitro. These results show that after oral administration of the herbal immunomodulator, the immunologically active macromolecules can contact the cells of the gut-associated lymphoid tissue and modulate the mucosal immune response.

A sulfated polysaccharide, fucoidan, enhances the immunomodulatory effects of lactic acid bacteria

Fucoidan, a sulfated polysaccharide contained in brown algae, has a variety of immunomodulatory effects, including antitumor and antiviral effects. On the other hand, lactic acid bacteria (LAB) also have immunomodulatory effects such as anti-allergic effects. In this study, we demonstrated that fucoidan enhances the probiotic effects of LAB on immune functions. By using Peyer's patch cells and spleen cells in vitro, fucoidan amplified interferon (IFN)-γ production in response to a strain of LAB, Tetragenococcus halophilus KK221, and this activity was abolished by desulfation of fucoidan. Moreover, this IFN-γ response was abolished by interleukin (IL)-12 neutralization. These results indicate that fucoidan enhanced IL-12 production in response to KK221, resulting in promoting IFN-γ production. In an in vivo study, Th1/Th2 immunobalance was most improved by oral administration of both fucoidan and KK221 to ovalbumin-immunized mice. These findings suggest that fucoidan can enhance a variety of beneficial effects of LAB on immune functions.

Kjellmaniella crassifolia Miyabe (Gagome) extract modulates intestinal and systemic immune responses.

Kjellmaniella crassifolia Miyabe (gagome) is a brown alga. Oral gagome administration (oral gagome) resulted in significant upregulation of IL-10 and IFNγ production by Peyer's patch cells. To assess the adjuvant activity of oral gagome, treated mice were subcutaneously injected with ovalbumin (OVA). The production of cytokines from antigen (Ag)-specific T cells in draining lymph nodes (dLN) and their proliferative response were significantly increased as compared with the control group. These enhancements were associated with increased CD44(hi)CD62L(-) activated/memory T cells in dLN as well as upregulation of Ag-specific IgA level in luminal contents. No upregulation of cytokine production by dLN T cells was observed in dectin-1-deficient mice, suggesting that the effect of gagome on cytokine production is largely dependent on the dectin-1 pathway despite its composite constituents. Our findings indicate that gagome is an effective immunomodulator and a potent adjuvant for both the intestinal and the systemic immune response.

The effect of orally administered glycogen on anti-tumor activity and natural killer cell activity in mice

Natural killer (NK) cells, innate immune effectors that mediate rapid responses to various antigens, play an important role in potentiating host defenses through the clearance of tumor cells and virally infected cells. By using enzymatically synthesized glycogen (ESG) with the same characteristics as natural glycogen, we examined whether orally administered glycogen enhances the innate defense of tumor-implanted mice and the cytotoxicity of NK cells. Oral administration of ESG led to the suppression of tumor proliferation and the prolongation of survival times of tumor-bearing mice. Splenic NK activities of BALB/c mice treated orally with ESG were significantly higher than those of water-treated mice, which were used as a negative control. In addition, intraduodenal injections of ESG gradually and markedly lowered splenic sympathetic nerve activity, which has an inverse correlation with NK activity. Furthermore, ESG activated Peyer's patch cells to induce the production of macrophage inflammatory protein-2 (MIP-2), interleukin-6 (IL-6), and immunoglobulin A (IgA) from these cells. These results demonstrated that orally administrated glycogen significantly enhanced the cytotoxicity of NK cells by acting on Peyer's patch cells and autonomic nerves, and eventually induced the potentiation of host defenses. We propose that glycogen functions not only as an energy source for life support but also as an oral adjuvant for immunopotentiation.

Functional Transforming Growth Factor-β Receptor Type II Expression by CD4+ T Cells in Peyer's Patches Is Essential for Oral Tolerance Induction

Our previous studies have shown that Peyer's patches (PPs) play a key role in the induction of oral tolerance. Therefore, we hypothesized that PPs are an important site for Transforming Growth Factor (TGF)- β signaling and sought to prove that this tissue is of importance in oral tolerance induction. We found that expression of TGF-β type II receptor (TGFβRII) by CD4+ T cells increases and persists in the PPs of normal C57BL/6 mice after either high- or low-dose feeding of OVA when compared to mesenteric lymph nodes (MLNs) and spleen. Approximately one-third of these TGFβRII+ CD4+ T cells express the transcription factor Foxp3. Interestingly, the number of TGFβRII+ CD4+ T cells in PPs decreased when OVA-fed mice were orally challenged with OVA plus native cholera toxin (CT). In contrast, numbers of TGFβRII+ CD4+ T cells were increased in the intestinal lamina propria (iLP) of these challenged mice. Further, these PP CD4+ TGFβRII+ T cells upregulated Foxp3 within 2 hours after OVA plus CT challenge. Mice fed PBS and challenged with OVA plus CT did not reveal any changes in TGFβRII expression by CD4+ T cells. In order to test the functional property of TGFβRII in the induction of oral tolerance, CD4dnTGFβRII transgenic mice, in which TGFβRII signaling is abrogated from all CD4+ T cells, were employed. Importantly, these mice could not develop oral tolerance to OVA. Our studies show a critical, dose-independent, role for TGFβRII expression and function by CD4+ T cells in the gut-associated lymphoid tissues, further underlining the vital role of PPs in oral tolerance.

Augmentation of cellular immunity and protection against influenza virus infection by bovine late colostrum in mice

ObjectiveWe investigated whether oral administration of skimmed and concentrated bovine late colostrum (SCBLC) activates the immune system and protects against influenza virus (Flu) infection. MethodsMurine Peyer's patch (PP) cells (2.5 105) were cultured in 0.1 ml RPMI-1640 supplemented with SCBLC at a concentration of 0, 0.1 or 1.0 mg/ml. To determine the levels of IL-12 and IFN-, supernatants were collected on day 3. Mice were orally administered sterile saline solution (control group), or 400 g/g body weight (SCBLC 400 group) or 2,000 g/g body weight (SCBLC 2,000 group) of SCBLC for three weeks. These mice were measured for natural killer (NK) cells activity on PP cells, splenocytes and lung cells. Also, these mice in the control and SCBLC 2,000 groups were infected with Flu and were measured for the accumulated symptom rate. ResultsIn PP cells cultured with SCBLC, the levels of IL-12 and IFN- were significantly increased in vitro. Oral administration of SCBLC to mice significantly increased NK cell activity of PP cells, splenocytes and lung cells. The accumulated symptom rate of the SCBLC 2,000 group was significantly lower than that of the control group in a mouse model of Flu infection. ConclusionThese results indicate that oral administration of SCBLC activates not only systemic cellular immunity but also local cellular immunity, such as in the respiratory tract, and that activation of cellular immunity is one of the mechanisms of amelioration of Flu infection.

XRCC1 suppresses somatic hypermutation and promotes alternative nonhomologous end joining in Igh genes

Activation-induced deaminase (AID) deaminates cytosine to uracil in immunoglobulin genes. Uracils in DNA can be recognized by uracil DNA glycosylase and abasic endonuclease to produce single-strand breaks. The breaks are repaired either faithfully by DNA base excision repair (BER) or mutagenically to produce somatic hypermutation (SHM) and class switch recombination (CSR). To unravel the interplay between repair and mutagenesis, we decreased the level of x-ray cross-complementing 1 (XRCC1), a scaffold protein involved in BER. Mice heterozygous for XRCC1 showed a significant increase in the frequencies of SHM in Igh variable regions in Peyer's patch cells, and of double-strand breaks in the switch regions during CSR. Although the frequency of CSR was normal in Xrcc1(+/-) splenic B cells, the length of microhomology at the switch junctions decreased, suggesting that XRCC1 also participates in alternative nonhomologous end joining. Furthermore, Xrcc1(+/-) B cells had reduced Igh/c-myc translocations during CSR, supporting a role for XRCC1 in microhomology-mediated joining. Our results imply that AID-induced single-strand breaks in Igh variable and switch regions become substrates simultaneously for BER and mutagenesis pathways.

A Matured Fruit Extract of Date Palm Tree (Phoenix dactylifera L.) Stimulates the Cellular Immune System in Mice

The immunomodulatory effects of a hot water extract from matured fruit of the date palm tree (Phoenix dactylifera L.) were investigated in comparison to those of prune and fig fruit in mice. The number of spleen IFN-γ(+)CD4(+), IFN-γ(+)CD49b(+) and IL-12(+)CD11b(+) cells was highest in mice given the date extract-added diet. Polyphenols identified in the date extract, such as chlorogenic acid, caffeic acid, pelargonin and ferulic acid, stimulated IFN-γ mRNA expression significantly in mouse Peyer's patch cell cultures. Chlorogenic acid and caffeic acid also increased the number of IFN-γ(+)CD4(+) cells significantly, while some polyphenols increased the number of IFN-γ(+)CD49b(+) and IL-12(+)CD11b(+) cells significantly. On the other hand, a 70% ethanol-insoluble date extract treated with trypsin increased the number of IFN-γ(+)CD49b(+) and IL-12(+)CD11b(+) cells significantly. These results indicate that some polyphenols and polysaccharides present in date fruit stimulate the cellular immune system in mice.

Naïve CD4+ T cells of Peyer's patches produce more IL-6 than those of spleen in response to antigenic stimulation

Peyer's patches (PPs) are potential sites where specific mucosal immune responses and oral tolerance are induced. The unique features of these immune responses are thought to occur in micromilieu and are largely affected by antigen-presenting cells (APCs) such as dendritic cells. In this study, we investigated the cytokine profiles induced by the activation of CD4+ T cells of PPs. PP cells from TCR transgenic mice secreted greater amounts of IL-5 and IL-6 than spleen cells after antigenic stimulation. IL-5 was mainly produced by PP non-T cells, whereas IL-6 was secreted by PP CD4+ cells. PPs contained two major populations including naïve and memory/activated CD4+ cells; both populations secreted IL-6 upon activation. We also found that CD4+/CD62Lhi naïve cells from PPs secreted a greater amount of IL-6 after stimulation than those from the spleen. Furthermore, subtraction and qPCR analyses revealed that PP CD4+/CD62Lhi cells express a greater amount of transcripts of GA-binding protein β subunit 1 than those of the spleen. These results suggest that naïve T cells as well as non-T cells and activated/memory T cells from PPs are distinct from their splenic counterparts and thus cause unique immune responses the in intestine.

Lactobacillus plantarum strain YU from fermented foods activates Th1 and protective immune responses

Lactic acid bacteria (LAB) are known to have effects on immune function. From 203 strains of LAB isolated from fermented foods, we selected a beneficial strain, Lactobacillus plantarum strain YU (LpYU), which has high interleukin (IL)-12-inducing activity in mouse peritoneal macrophages. This activity of LpYU was partially mediated by Toll-like receptor (TLR) 2, but not TLR4 or TLR9. Oral administration of LpYU to ovalbumin (OVA)-immunized mice caused suppression of serum OVA-specific immunoglobulin E (IgE) levels, enhancing interferon (IFN)-γ production from spleen cells in response to OVA. Furthermore, LpYU enhanced natural killer cell activity in spleen cells and the production of IgA from Peyer's patch cells. Because activation of Th1 immune responses and IgA production induce antiviral effects, we evaluated the inhibitory effects of LpYU against the influenza A virus (A/NWS/33, H1N1) (IFV). Oral administration of LpYU suppressed viral proliferation in the lungs and in bronchoalveolar lavage fluids (BALFs). Both levels of IFV-specific secretory IgA in BALF and feces and titers of IFV-specific neutralizing antibody in BALFs and sera were increased. These results indicate that LpYU has a protective effect against IFV replication. We conclude that this strain has a beneficial effect in activating Th1 immune responses and preventing viral infection.

Leucocyte Infiltration in Lymphoid Organs and Peritoneal Cavity upon Immunization: Dependence on Circadian Rhythmicity and Melatonin 24-H Profile

Circadian rhythmicity and melatonin secretion influence many functions in mammals, including the immune system function. The aim of our study is to investigate the effect of suppression of melatonin synthesis (caused by constant lighting) on the quantity of leucocytes in immunized BALB/c mice. The mice were kept under different lighting conditions: (1) customary environmental lighting; (2) constant exposure to light; (3) exposure to light and daily melatonin treatment. The disrupted melatonin synthesis had no effect on the number of cells in the thymus, bone marrow, spleen, lymph nodes and Peyer's patches of immunized mice. However, the mice kept under constant light had an increased number of leucocytes in the peritoneal cavity when immunizations were performed in the evening. Melatonin treatment normalized the cell number. When the immunizations were performed in the morning, the numbers of cells in peritoneum of mice kept under constant lighting conditions were lower compared to mice exposed to normal lighting conditions. The number of cells of mice kept in normal light/dark conditions was significantly higher when the immunizations were performed in the morning. The number of peritoneal cells, however, did not depend on the immunization time when mice were kept under constant lighting. In conclusion, the amount of peritoneal cells in mice immunized with T cell-dependent antigens seems to be related to circadian rhythmicity, melatonin production and immunization timing.

Phenolic lipid ingredients from cashew nuts

Five new phenolic lipids, 2-(8"Z-eicosenoyl)-6-(8'Z-pentadecenyl) salicylic acid (3), 2-(9"Z-hexadecenoyl)-6-(8'Z, 11'Z-pentadecadienyl) methyl salicylate (5), 2-(10"Z, 13"Z-nonadecadienoyl)-6-(8'Z, 11'Z-pentadecadienyl) salicylic acid (6), 2-(16"Z-pentacosenoyl)-6-(8'Z-pentadecenyl) salicylic acid (7) and 2-(9"Z-octadecenoyl)-6-(8'Z, 11'Z-pentadecadienyl) methyl salicylate (8), and three known compounds, cardols (1), anacardic acid (2) and cardanols (4), were isolated from the nuts of the cashew, Anacardium occidentale L. The structures were established on the basis of detailed MS and NMR spectroscopic analyses. Compound 1 highly enhanced both Th-1 (IL-2, IFN-γ) and Th-2 (IL-4, IL-5) cytokine production, and compounds 7 and 8 highly increased cytokine IL-2 and IFN-γ production in response to concanavalin A in cultured murine Peyer's patch cells ex vivo. The isolated compounds showed moderate inhibitory activities on cytochrome CYP3A4 enzyme.

Ovine Serum Immunoglobulin Has Immunomodulatory Effects in Growing Rats Gavaged with Salmonella enteritidis1

AbstractIn this study, we aimed to determine whether orally administered ovine serum Ig modulate aspects of immunity and associated gut microflora in growing rats challenged with Salmonella enteritidis. The 4 groups consisted of rats fed a casein-based control diet (BD; ungavaged) and 3 groups of rats gavaged with 1 107 viable Salmonella enteritidis and fed a BD diet, a BD diet containing freeze-dried ovine Ig (FDOI), or a BD diet containing inactivated ovine Ig (IOI). The rats were randomly allocated to 1 of the 4 diets (n = 15) and consumed it for 18 d. They were orally gavaged on d 15. Phagocytic activity of peripheral blood leukocyte and lymphocyte proliferation in the presence of the concanavalin A (ConA) were greater (P < 0.05) in the ungavaged BD- and gavaged FDOI-fed rats than in the gavaged rats fed either the BD or IOI diet. ConA-stimulated Peyer's patch cells and splenocytes from the gavaged rats fed the FDOI diet produced more IFN?, IgA, and IgG than the gavaged rats fed either the BD or IOI diet (P < 0.05). The gavaged FDOI-fed rats had higher ileal and colonic digesta and plasma concentrations of anti-Salmonella secretory sIgA and secretory sIgG (P < 0.05). DNA analysis of a denatured gradient gel electrophoresis profile revealed that 6 of 10 bands had sequence similarity to probiotic strains of bacteria in the ileum and colon of the gavaged FDOI-fed rats. In conclusion, an ovine Ig fraction modulated various indices of immune function and associated gut microflora in growing rats inoculated with Salmonella.

Novel Bregs down-regulate TLR9-induced cytokine responses in sheep Peyer's patches

Regulation of TLR responses is required in the intestine to prevent unnecessary responses to commensal microorganisms and maintain tissue homeostasis. Several mechanisms have been proposed for the regulation of TLR responses in intestinal epithelial and lamina propria cells. However, whether this regulation occurs in Peyer's patches (PP) is not known. While investigating cellular responses to the TLR9 agonist CpG ODN, we observed that PP cells responded poorly to CpG ODN stimulation despite expressing TLR9. We hypothesized that PP cells produced the immunoregulatory cytokine IL-10 which suppressed TLR-induced cytokine responses. In vitro neutralization of IL-10 or depletion of CD21+ B cells from PP resulted in significant increases in IL-12, IFNγ and IFNα responses in PP cells stimulated with CpG ODN. Essentially, our investigation have identified a novel population of IL-10-secreting B cells in PP with regulatory functions (Bregs). These Bregs may play an important role in the maintenance of intestinal homeostasis.

Characterization of antigen-presenting cells induced by intragastric immunization with recombinant chimeric immunogens constructed from Streptococcus mutans AgI/II and type I or type II heat-labile enterotoxins

Intragastric (i.g.) immunization with recombinant chimeric proteins constructed from the saliva-binding region (SBR) of Streptococcus mutans surface antigen AgI/II and the A2/B subunits of enterobacterial heat-labile enterotoxins has been successfully used to induce salivary and circulating antibodies against S.mutans that have protective potential against dental caries. To investigate the mode of action of these vaccine constructs, mice were immunized i.g. with chimeric proteins constructed from SBR and cholera toxin (CT) or the type II enterotoxins of Escherichia coli, LT-IIa and LT-IIb. Antigen-presenting cells (APC) in Peyer's patches (PP) and mesenteric lymph nodes (MLN) were characterized by flow cytometry. Compared with immunization with SBR alone, chimeric proteins SBR-LTIIaA2/B and SBR-LTIIbA2/B increased the number of B cells and macrophages in PP and diminished B cell numbers in MLN, whereas SBR-CTA2/B diminished the numbers of B cells and macrophages in PP and MLN. Immunization with all three chimeric proteins led to upregulation of MHC class II molecules and co-stimulatory receptors CD40, CD80, and CD86 especially on dendritic cells in PP and also on APC in MLN. The results provide a molecular basis for the enhanced immune responses induced by chimeric proteins compared with uncoupled antigen, and for differential responses to chimeric proteins based on CT or type II enterotoxins.

P‐selectin glycoprotein ligand‐1 modulates immune inflammatory responses in the enteric lamina propria

P-selectin glycoprotein ligand-1 (PSGL-1), a leukocyte adhesion receptor that interacts with selectins, induces a tolerogenic programme in bone marrow-derived dendritic cells (DCs), which in turn promotes the generation of T regulatory (Treg) lymphocytes. In the present study, we have used a mouse model of dextran sulphate sodium (DSS)-induced colitis and studied the characteristics of the inflammatory cell infiltrate in the lamina propria (LP), mesenteric lymph nodes (mLNs) and Peyer's patches (PPs) to assess the possible role of PSGL-1 in the modulation of the enteric immune response. We have found that untreated PSGL-1-deficient mice showed an altered proportion of innate and adaptive immune cells in mLNs and PPs as well as an activated phenotype of macrophages and DCs in the colonic LP that mainly produced pro-inflammatory cytokines. Administration of an anti-PSGL-1 antibody also reduced the total numbers of macrophages, DCs and B cells in the colonic LP, and induced a lower expression of MHC-II by DCs and macrophages. After DSS treatment, PSGL-1(-/-) mice developed colitis earlier and with higher severity than wild-type (WT) mice. Accordingly, the colonic LP of these animals showed an enhanced number of Th1 and Th17 lymphocytes, with enhanced synthesis of IL-1α, IL-6 and IL-22, and increased activation of LP macrophages. Together, our data indicate that PSGL-1 has a relevant homeostatic role in the gut-associated lymphoid tissue under steady-state conditions, and that this adhesion receptor is able to down-regulate the inflammatory phenomenon in DSS-induced colitis.