THE ISSUE OF HISTOLOGICAL IDENTIFICATION OF М-CELLS IN THE PEYER'S PATCHES OF ALBINO RAT SMALL INTESTINE

OBJECTIVE

The aim: Based on the above cytological signs of M-cells, we set the goal of more detailed clarification of some of their topological relationships with other enterocytes in the follicle-associated epithelium of Peyer's patches of albino rat small intestine.

PATIENTS AND METHODS

Materials and methods: 10 mature albino male rats weighted 200,0±20,0 g were involved into the study. Anatomical dissection with the sampling of the sections of the small intestine containing Peyer's patches was carried out with subsequent embedment of the latter into paraffin blocks and making of serial histological sections of 4 μm thick in the cross-section of the small intestine, followed with hematoxylin-eosin staining. The specimens were studied and documented on the "Konus" light microscope equipped. Morphometric characteristics of the specimen tissue structures were studied using the Sigeta X 1 mm/100 Div.x0.01mm stage micrometer.

RESULTS

Results: The findings of the study revealed enterocytes with phagocytic properties found in the lymphoid-associated epithelium of Peyer's patches of the small intestine of albino rats. Moreover, if they are clearly visualized at the light-optical level, then M-cells are poorly recognizable, which is consistent with a similar assessment made by other authors.

CONCLUSION

Conclusions: Given this, the issue on the topology and functional purpose of M-cells remains uncertain to date and, thereby, the prospect of further research is being outlined, which, in our opinion, can be successful using the method of stereomorphological analysis. For this purpose, multilayer plastic reconstruction methods can be used for serial semi-thin sections of Peyer's patches embedded in epoxy resin, according to the requirements of transmission electron microscopy.

Effect of Low-Immunogenic Yogurt Drinks and Probiotic Bacteria on Immunoreactivity of Cow's Milk Proteins and Tolerance Induction-In Vitro and In Vivo Studies

There is no effective therapy for milk allergy. The role of lactic acid bacteria (LAB) and probiotics in protection against allergy-related outcomes is still under investigation. The aim of the study was to evaluate the immunomodulative and therapeutic potential of yogurt drinks in cow's milk allergy (CMA) management. We compared immunoreactivity of α-casein (α-CN), β-casein (β-CN), κ-casein (κ-CN), α-lactalbumin (α-LA), and β-lactoglobulin (β-LG) in 27 yogurt drinks fermented with different basic yogurt cultures, or yogurt cultures enriched with Lactobacillus plantarum and/or Bifidobacterium lactis strains, by competitive ELISA assay. Drinks with the lowest antigenic potential were used as allergoids for CMA therapy. BALB/c mice were sensitized via intraperitoneal injection of α-CN + β-LG mixture with aluminum adjuvant, and gavaged with increasing doses of selected low-immunogenic drinks (YM-basic, or YM-LB-enriched with L. plantarum and B. lactis) to induce tolerance. Milk- or phosphate-buffered saline (PBS)-dosed mice served as controls. Compared to milk, the immunoreactivity of proteins in drinks increased or decreased, depending on the bacterial sets applied for fermentation. Only a few sets acted synergistically in reducing immunoreactivity. The selected low-immunogenic drinks stimulated allergic mice for profiling Th2 to Th1 response and acquire tolerance, and the effect was greater with YM-LB drink, which during long-lasting interventional feeding strongly increased the secretion of regulatory cytokines, i.e., IL-10 and TGF-β, and IgA and decreased IL-4, IgE, and anti-(α-CN + β-LG) IgG1. The studies revealed variations in the potency of yogurt bacteria to change allergenicity of milk proteins and the need for their strict selection to obtain a safe product for allergy sufferers. The YM-LB drink with reduced antigenic potential may be a source of allergoids used in the immunotherapy of IgE mediated CMA, but further clinical or volunteer studies are required.

Molecular Drivers of Lymphocyte Organization in Vertebrate Mucosal Surfaces: Revisiting the TNF Superfamily Hypothesis

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.

Effect of the Lactococcus Lactis 11/19-B1 Strain on Atopic Dermatitis in a Clinical Test and Mouse Model

Some lactic acid bacteria (LAB) are known to improve atopic dermatitis (AD) through the regulation and stimulation of the host immune system. In this study, we found that ingestion of yogurt containing Lactococcus lactis 11/19-B1 strain (L. lactis 11/19-B1) daily for 8 weeks significantly improved the severity scoring of atopic dermatitis (SCORAD) system score from 38.8 ± 14.4 to 24.2 ± 12.0 in children suffering from AD. We tried to identify which LAB species among the five species contained in the test yogurt contributed to the improvement in AD pathology using an AD mouse model induced by repeated application of 1-fluoro-2, 4-dinitrobenzene (DNFB). AD-like skin lesions on the dorsal skin and ear were most improved by L. lactis 11/19-B1 intake among the five LAB species. In addition, analysis of CD4+ T cell subsets in Peyer’s patches (PPs) and cervical lymph nodes (CLNs) indicated that the intake of L. lactis 11/19-B1 generally suppressed all subsets related to inflammation, i.e., Th1, Th2 and Th17, instead of activating the suppressive system, Treg, in the AD mouse model. Histological observations showed ingestion of L. lactis 11/19-B1 significantly suppressed severe inflammatory findings, such as inflammatory cell filtration, epidermal erosion and eosinophil infiltration. These results suggest that the immunomodulatory effects of L. lactis 11/19-B1 contribute to improvements in AD pathology.

1-(4-nitrobenzenesulfonyl)-4-penylpiperazine increases the number of Peyer's patch-associated regenerating crypts in the small intestines after radiation injury

OBJECTIVE

Exposure to lethal doses of radiation has severe effects on normal tissues. Exposed individuals experience a plethora of symptoms in different organ systems including the gastrointestinal (GI) tract, summarized as Acute Radiation Syndrome (ARS). There are currently no approved drugs for mitigating GI-ARS. A recent high-throughput screen performed at the UCLA Center for Medical Countermeasures against Radiation identified compounds containing sulfonylpiperazine groups with radiation mitigation properties to the hematopoietic system and the gut. Among these 1-[(4-Nitrophenyl)sulfonyl]-4-phenylpiperazine (Compound #5) efficiently mitigated gastrointestinal ARS. However, the mechanism of action and target cells of this drug is still unknown. In this study we examined if Compound #5 affects gut-associated lymphoid tissue (GALT) with its subepithelial domes called Peyer's patches.

METHODS

C3H mice were irradiated with 0 or 12 Gy total body irradiation (TBI). A single dose of Compound #5 or solvent was administered subcutaneously 24 h later. 48 h after irradiation the mice were sacrificed, and the guts examined for changes in the number of visible Peyer's patches. In some experiments the mice received 4 daily injections of treatment and were sacrificed 96 h after TBI. For immune histochemistry gut tissues were fixed in formalin and embedded in paraffin blocks. Sections were stained with H&E, anti-Ki67 or a TUNEL assay to assess the number of regenerating crypts, mitotic and apoptotic indices. Cells isolated from Peyer's patches were subjected to immune profiling using flow cytometry.

RESULTS

Compound #5 significantly increased the number of visible Peyer's patches when compared to its control in non-irradiated and irradiated mice. Additionally, assessment of total cells per Peyer's patch isolated from these mice demonstrated an overall increase in the total number of Peyer's patch cells per mouse in Compound #5-treated mice. In non-irradiated animals the number of CD11b^high in Peyer's patches increased significantly. These Compound #5-driven increases did not coincide with a decrease in apoptosis or an increase in proliferation in the germinal centers inside Peyer's patches 24 h after drug treatment. A single dose of Compound #5 significantly increased the number of CD45⁺ cells after 12 Gy TBI. Importantly, 96 h after 12 Gy TBI Compound #5 induced a significant rise in the number of visible Peyer's patches and the number of Peyer's patch-associated regenerating crypts.

CONCLUSION

In summary, our study provides evidence that Compound #5 leads to an influx of immune cells into GALT, thereby supporting crypt regeneration preferentially in the proximity of Peyer's patches.

Morphogenesis of Epithelial Lesions in the Lymphoid Patches of Fischer 344 Rats during Cyclosporine-A-Induced Prolonged Immunosuppression

Alterations of intestinal lymphoid patches induced by cyclosporine A (CS-A) were studied in male Fischer 344 rats. Continuous treatment with CS-A (10 mg/kg b.w. by gavage daily) resulted in lymphocyte deficiency of the intestinal lymphoid patches followed by progressive replacement of the lymphoid tissue by cystic and glandular epithelial structures and single cells positive for epithelium-associated immunohistochemical markers. Cessation of CS-A administration led to regression of the alterations and a moderate recovery of the lymphoid patches. Morphologic changes induced at the epithelial-lymphoid border may be a useful parameter to estimate immunotoxicity.

Bombesin Prevents the Atrophy of Peyer's Patches and the Dysfunction of M Cells in Rabbits Receiving Long-Term Parenteral Nutrition

BACKGROUND

Long-term parenteral nutrition (PN) induces atrophy of the gut-associated lymphoid tissue (GALT). We examined whether bombesin could ameliorate this atrophy of Peyer's patches and the down-regulation of particle transport by M cells, which was also observed in rabbits undergoing PN.

METHODS

Adult female rabbits were randomized into 6 groups to receive chow ad libitum, chow + bombesin, PN, or PN + bombesin (20 microg/kg, subcutaneously every 8 hours) for 2 or 4 weeks. At the end of each nutrition period, a laparotomy was performed under anesthesia and a suspension of 1 x 10(10)/mL of 0.5-microm fluorescent microspheres was injected into the lumen of intestinal segments containing Peyer's patches and incubated for 2 hours. After the incubation, segments were harvested and prepared for light microscopy, immunohistochemistry, fluorescent microscopy, and electron microscopy.

RESULTS

Long-term PN reduced the size of ileal Peyer's patches, the number of microspheres that was taken up into the follicle-associated epithelium of lymphoid nodules, and the area of Peyer's patch surface occupied by M cells. The number of intraepithelial lymphocytes within the follicle-associated epithelium near the perifollicular crypts of Peyer's patches was also reduced by long-term PN. These consequences were dramatically ameliorated by treatment with bombesin. No ultrastructural alteration of the M cells of Peyer's patches was found in the chow, the PN, or the PN + bombesin groups.

CONCLUSIONS

Bombesin prevents PN-induced atrophy of GALT, reduction of M cell numbers, and decrease in particulate transport by M cells during long-term PN. Bombesin may modulate the genesis of and particulate transport by M cells through stimulation of lymphoid cells in Peyer's patch epithelium near perifollicular crypts, where M cells and other constituents of lymphoid follicle epithelium are generated, thereby preserving mucosal immunity.

Effects of Cyclosporin A and Cyclophosphamide on Peyer’s Patches in Rat, Exposed in utero and Neonatally or During Adult Age

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.

Leukocyte populations and IL-6 in the tumor microenvironment of an orthotopic colorectal cancer model

Colorectal cancer (CRC) is a major health problem worldwide. It is often diagnosed late due to its asymptomatic nature. As with all cancers, an immune reaction is involved; however, in CRC, it is unknown if this immune response is favorable or unfavorable for disease progression. In this study, the immune response in mesenteric lymph nodes (MLNs) and Peyer's patches was investigated during development of CRC in an orthotopic mouse model. CRC was induced by injecting CT26 cells into the cecum wall of BALB/c mice. Flow cytometry was used to analyze leukocyte populations involved in tumor immunity in MLNs and Peyer's patches. Cryostat sections for immunohistochemistry were prepared from the caecum and colon from CRC-induced and sham-operated animals. Cytokines produced by mouse CT26 cell line were measuredin vitroandin vivo Significant increases in the number of CD8(+)/TCR(+)and CD49b(+)/TCR(-)(natural killer) cells were found in MLNs and Peyer's patches in the CRC group. In addition, γδT cells were present in the lamina propria of the colon tissues from sham-operated mice, but absent in the colon tissues from mice with CRC. Immunohistochemical analysis of tumorous tissues showed eosinophil, CD69(+)T cell, and CD11b(+)cell infiltration. Bothin vitroandin vivoCT26 tumor cells were interleukin (IL)-6 positive. In addition, tumor-infiltrating CD45(+)cells were also IL-6 positive. In summary, the kinetics of the immune response to CRC and the key effector lymphocytes that are implicated in tumor immunity are demonstrated. Furthermore, IL-6 is a key cytokine present within the tumor microenvironment.

Central Role of Core Binding Factor β2 in Mucosa-Associated Lymphoid Tissue Organogenesis in Mouse

Mucosa-associated lymphoid tissue (MALT) is a group of secondary and organized lymphoid tissue that develops at different mucosal surfaces. Peyer's patches (PPs), nasopharynx-associated lymphoid tissue (NALT), and tear duct-associated lymphoid tissue (TALT) are representative MALT in the small intestine, nasal cavity, and lacrimal sac, respectively. A recent study has shown that transcriptional regulators of core binding factor (Cbf) β2 and promotor-1-transcribed Runt-related transcription factor 1 (P1-Runx1) are required for the differentiation of CD3-CD4+CD45+ lymphoid tissue inducer (LTi) cells, which initiate and trigger the developmental program of PPs, but the involvement of this pathway in NALT and TALT development remains to be elucidated. Here we report that Cbfβ2 plays an essential role in NALT and TALT development by regulating LTi cell trafficking to the NALT and TALT anlagens. Cbfβ2 was expressed in LTi cells in all three types of MALT examined. Indeed, similar to the previous finding for PPs, we found that Cbfβ2-/- mice lacked NALT and TALT lymphoid structures. However, in contrast to PPs, NALT and TALT developed normally in the absence of P1-Runx1 or other Runx family members such as Runx2 and Runx3. LTi cells for NALT and TALT differentiated normally but did not accumulate in the respective lymphoid tissue anlagens in Cbfβ2-/- mice. These findings demonstrate that Cbfβ2 is a central regulator of the MALT developmental program, but the dependency of Runx proteins on the lymphoid tissue development would differ among PPs, NALT, and TALT.

HGF Gene Modification in Mesenchymal Stem Cells Reduces Radiation-Induced Intestinal Injury by Modulating Immunity

Background

Effective therapeutic strategies to address intestinal complications after radiation exposure are currently lacking. Mesenchymal stem cells (MSCs), which display the ability to repair the injured intestine, have been considered as delivery vehicles for repair genes. In this study, we evaluated the therapeutic effect of hepatocyte growth factor (HGF)-gene-modified MSCs on radiation-induced intestinal injury (RIII).

Methods

Female 6- to 8-week-old mice were radiated locally at the abdomen with a single 13-Gy dose of radiation and then treated with saline control, Ad-HGF or Ad-Null-modified MSCs therapy. The transient engraftment of human MSCs was detected via real-time PCR and immunostaining. The therapeutic effects of non- and HGF-modified MSCs were evaluated via FACS to determine the lymphocyte immunophenotypes; via ELISA to measure cytokine expression; via immunostaining to determine tight junction protein expression; via PCNA staining to examine intestinal epithelial cell proliferation; and via TUNEL staining to detect intestinal epithelial cell apoptosis.

Results

The histopathological recovery of the radiation-injured intestine was significantly enhanced following non- or HGF-modified MSCs treatment. Importantly, the radiation-induced immunophenotypic disorders of the mesenteric lymph nodes and Peyer’s patches were attenuated in both MSCs-treated groups. Treatment with HGF-modified MSCs reduced the expression and secretion of inflammatory cytokines, including tumor necrosis factor alpha (TNF-α) and interferon-gamma (IFN-γ), increased the expression of the anti-inflammatory cytokine IL-10 and the tight junction protein ZO-1, and promoted the proliferation and reduced the apoptosis of intestinal epithelial cells.

Conclusions

Treatment of RIII with HGF-gene-modified MSCs reduces local inflammation and promotes the recovery of small intestinal histopathology in a mouse model. These findings might provide an effective therapeutic strategy for RIII.

Proliferation and apoptosis of Peyer's patches and its lymphocytes in experimental terminal ileitis

This study will provide guide for the terminal ileitis in clinical diagnosis and treatment. The animals were been done terminal ileum-cecum side to side anastomosis, terminal ileum operation line and only anesthesia treatment, respectively. The model group presented acute inflammation after surgery for 2 weeks and the inflammation was limited to the mucosal layer. Animals presented chronic inflammation to 8 weeks, mucosal membrane was given priority to with lymphocytic infiltrates. In 2 weeks and 4 weeks, the number of Peyer's patches (PP knot) and PP knot lymphocytes increased significantly in the model group (P < 0.05, P < 0.01). At 8 weeks, the suture group and the model group presented a large number of lymphocytic apoptosis (P < 0.01). Rat ileal PP knot lymphocyte small molecule DNA showed typical "trapezoid" bands. We observed apparent morphology of apoptosis and crescent-shaped nucleus. Continuous immune response in terminal ileitis plays a considerable role in the process of the disease.

Sequential development of lesions 3, 6, 9, and 12 months after experimental infection of goat kids with Mycobacterium avium subsp paratuberculosis

The development of lesions after infection with Mycobacterium avium subsp paratuberculosis (MAP) was examined in an experimental infection model. Goat kids were orally inoculated 10 times with 10 mg bacterial wet mass of MAP (total dose 2.6 × 10(8) colony-forming units). Six to 7 inoculated goats and 3 controls were autopsied 3, 6, 9, and 12 months postinoculation (mpi), lesions were documented, and samples were collected for histology, immunohistochemistry (IHC), and bacterial culture. Twenty-five of the 26 inoculated goats did not develop clinical signs. Macroscopic lesions were detected in 3 of the 7 inoculated goats as soon as 3 mpi. Jejunal Peyer's patches (JPPs) were thickened and had ulcerated surfaces and circumscribed serositis. Characteristic granulomatous infiltrates were seen in all goats in gut-associated lymphoid tissues (GALTs), especially JPPs and lymphoid tissue at the ileocecal valve and in intestinal lymph nodes. Granulomatous intestinal infiltrates not associated with GALT were seen beginning at 6 mpi and with increasing frequency thereafter. Interindividual differences in lesions were most pronounced at 12 mpi, varying from mild focal paucibacillary to severe diffuse multibacillary patterns. Bacterial culture of MAP confirmed the IHC findings but was more sensitive and revealed widespread dissemination at 3 and 12 mpi. Granulomatous arteritis was found in intestinal submucosa of several goats. This may contribute to the spreading of MAP to the intestinal wall and possibly systemically. The different lesions observed during the clinically inapparent period of paratuberculosis are most likely indicators for the later progression of infection and development of clinical disease.

Latency locus complements MicroRNA 155 deficiency in vivo

MicroRNA-155 (miR-155) is expressed in many cancers. It also executes evolutionary conserved functions in normal B cell development. We show that the Kaposi's sarcoma-associated herpesvirus (KSHV) latency locus, which contains an ortholog of miR-155, miR-K12-11, complements B cell deficiencies in miR-155 knockout mice. Germinal center (GC) formation was rescued in spleen, lymph node, and Peyer's patches. Immunoglobulin levels were restored. This demonstrates that KSHV can complement the normal, physiological function of miR-155.

Immunomodulation by Bifidobacterium infantis 35624 in the murine lamina propria requires retinoic acid-dependent and independent mechanisms

Appropriate dendritic cell processing of the microbiota promotes intestinal homeostasis and protects against aberrant inflammatory responses. Mucosal CD103⁺ dendritic cells are able to produce retinoic acid from retinal, however their role in vivo and how they are influenced by specific microbial species has been poorly described. Bifidobacterium infantis 35624 (B. infantis) feeding to mice resulted in increased numbers of CD103⁺retinaldehyde dehydrogenase (RALDH)⁺ dendritic cells within the lamina propria (LP). Foxp3⁺ lymphocytes were also increased in the LP, while T_H1 and T_H17 subsets were decreased. 3,7-dimethyl-2,6-octadienal (citral) treatment of mice blocked the increase in CD103⁺RALDH⁺ dendritic cells and the decrease in T_H1 and T_H17 lymphocytes, but not the increase in Foxp3⁺ lymphocytes. B. infantis reduced the severity of DSS-induced colitis, associated with decreased T_H1 and T_H17 cells within the LP. Citral treatment confirmed that these effects were RALDH mediated. RALDH⁺ dendritic cells decreased within the LP of control inflamed animals, while RALDH⁺ dendritic cells numbers were maintained in the LP of B. infantis-fed mice. Thus, CD103⁺RALDH⁺ LP dendritic cells are important cellular targets for microbiota-associated effects on mucosal immunoregulation.

Loss of function of the mouse Sharpin gene results in Peyer's patch regression

Peyer’s patches (PP) are an important component in the immune response against intestinal pathogens. Two independent, spontaneous mutations in the mouse Sharpin gene (Sharpin^cpdm and Sharpin^cpdm-Dem) result in the absence of PP and disrupted splenic white pulp in adult mice, although a full complement of lymph nodes is present. Here we report that rudimentary PP begin to develop in Sharpin^cpdm mice during embryogenesis, but lack the organizational patterns that are typical of this tissue. In the present study, small intestines examined at weekly intervals from birth to maturity showed spontaneous regression of PP in mutant mice with concurrent infiltration of granulocytes. At 5 to 6 weeks of age, only indistinct remnants of granulocytic accumulations remain. Transplantation of normal bone marrow into Sharpin^cpdm mice at 7 days of age did not prevent regression of PP in bone marrow chimeras examined at 7 to 8 weeks of age. These findings indicate that SHARPIN expression is required for the normal development and maintenance, but not initiation, of PP.

[Morpho functional state of the peripheral organs of the immune system in rats after the hypokinesia and in the period of rehabilitation]

Using the quantitative methods, the remodeling of the cytoarchitectonics of the morpho-functional zones in the grouped lymphoid nodules (GLN) or Peyer's patches and in the mesenteric lymph nodes (MLN) were studied in 30 rats after 30-day-long exposure to hypokinesia and during the period of rehabilitation (30 days after hypokinesia discontinuation). It was found that following the hypokinesia the germinal centers in lymphoid nodules in GLN retained the lymphocytopoiesis, while in the internodular zone the proportion of immature cells was increased and plasma cells appeared. In the similar structural zones of MLN, the complete suppression of lymphocytopoiesis and T-cell maturation was noted. During the rehabilitation period, the cytoarchitectonic indexes recovery was more pronounced in GLN than in MLN. However, the quantitative parameters of their cellular composition did not reach the values found in the group of intact of animals.

18β-glycyrrhetinic acid delivered orally induces isolated lymphoid follicle maturation at the intestinal mucosa and attenuates rotavirus shedding

Glycyrrhizin, an abundant bioactive component of the medicinal licorice root is rapidly metabolized by gut commensal bacteria into 18β-glycyrrhetinic acid (GRA). Either or both of these compounds have been shown to have antiviral, anti-hepatotoxic, anti-ulcerative, anti-tumor, anti-allergenic and anti-inflammatory activity in vitro or in vivo. In this study, the ability of GRA to modulate immune responses at the small intestinal mucosa when delivered orally was investigated. Analysis of cytokine transcription in duodenal and ileal tissue in response to GRA treatment revealed a pattern of chemokine and chemokine receptor gene expression predictive of B cell recruitment to the gut. Consistent with this finding, GRA induced increases in CD19(+) B cells in the lamina propria and B220(+) B cell aggregates framed by CD11c(+) dendritic cells in structures resembling isolated lymphoid follicles (ILF). Using a mouse model of rotavirus infection, GRA reduced the duration of viral antigen shedding, and endpoint serum antibody titers were higher in GRA-treated animals. Together the data suggest GRA delivered orally augments lymphocyte recruitment to the intestinal mucosa and induces maturation of B cell-rich ILF independently of ectopic antigenic stimulus. These results provide further support a role for dietary ligands in modulation of dynamic intestinal lymphoid tissue.

Interactions with M cells and macrophages as key steps in the pathogenesis of enterohemorrhagic Escherichia coli infections

Enterohemorrhagic Escherichia coli (EHEC) are food-borne pathogens that can cause serious infections ranging from diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Translocation of Shiga-toxins (Stx) from the gut lumen to underlying tissues is a decisive step in the development of the infection, but the mechanisms involved remain unclear. Many bacterial pathogens target the follicle-associated epithelium, which overlies Peyer's patches (PPs), cross the intestinal barrier through M cells and are captured by mucosal macrophages. Here, translocation across M cells, as well as survival and proliferation of EHEC strains within THP-1 macrophages were investigated using EHEC O157:H7 reference strains, isogenic mutants, and 15 EHEC strains isolated from HC/HUS patients. We showed for the first time that E. coli O157:H7 strains are able to interact in vivo with murine PPs, to translocate ex vivo through murine ileal mucosa with PPs and across an in vitro human M cell model. EHEC strains are also able to survive and to produce Stx in macrophages, which induce cell apoptosis and Stx release. In conclusion, our results suggest that the uptake of EHEC by M cells and underlying macrophages in the PP may be a critical step in Stx translocation and release in vivo. A new model for EHEC infection in humans is proposed that could help in a fuller understanding of EHEC-associated diseases.

Exosome-producing follicle associated epithelium is not involved in uptake of PrPd from the gut of sheep (Ovis aries): an ultrastructural study

In natural or experimental oral scrapie infection of sheep, disease associated prion protein (PrP(d)) often first accumulates in Peyer's patch (PP) follicles. The route by which infectivity reaches the follicles is unknown, however, intestinal epithelial cells may participate in intestinal antigenic presentation by delivering exosomes as vehicles of luminal antigens. In a previous study using an intestinal loop model, following inoculation of scrapie brain homogenate, inoculum associated PrP(d) was detected by light microscopy shortly (15 minutes to 3.5 hours) after inoculation in the villous lacteals and sub-mucosal lymphatics. No PrP(d) was located within the follicle-associated epithelium (FAE), sub-FAE domes or the PP follicles. To evaluate this gut loop model and the transportation routes in more detail, we used electron microscopy (EM) to study intestinal tissues exposed to scrapie or control homogenates for 15 minutes to 10 days. In addition, immuno-EM was used to investigate whether exosomes produced in the FAE may possess small amounts of PrP(d) that were not detectable by light microscopy. This study showed that the integrity of the intestinal epithelium was sustained in the intestinal loop model. Despite prominent transcytotic activity and exosome release from the FAE of the ileal PP in sheep, these structures were not associated with transportation of PrP(d) across the mucosa. The study did not determine how infectivity reaches the follicles of PPs. The possibility that the infectious agent is transported across the FAE remains a possibility if it occurs in a form that is undetectable by the methods used in this study. Infectivity may also be transported via lymph to the blood and further to all other lymphoid tissues including the PP follicles, but the early presence of PrP(d) in the PP follicles during scrapie infection argues against such a mechanism.

The "intraendothelial canalicular formation": the route for lymphocyte diapedesis at the level of peripheral and mucosa-associated lymphoid tissue HEVs

How the lymphocyte crosses the blood endothelium during transendothelial migration is demonstrated through the study of serial sections of high endothelial venules (HEVs) of peripheral (mesenteric lymph nodes) and mucosa-associated lymphoid tissue (Peyer's patches, vermiform appendix) during normal lymphocyte homing and experimental intestinal inflammation. The sequence of serial ultrastructural features of lymphocytes englobed in the endothelial wall at different moments of transmigration made it possible to bring out that their transendothelial migration toward the extracellular matrix of lymphoid tissues occurs through an intraendothelial canalicular formation constituted by two adjacent endothelial cells that have closed interendothelial junctions. This intraendothelial canalicular formation, morphologically unlike the transcellular and paracellular migratory pathways, is an innovative model of migratory route for lymphocyte diapedesis that does not compromise the continuity of the endothelial wall. The increased presence of lymphocytes and intraendothelial canalicular formations during experimental inflammation and the metabolic hyperactivity of the spring/summer months compared to the lethargic fast in Chiropters underscores an influence on lymphocyte traffic through the HEVs of the peripheral and mucosa-associated lymphoid tissue.

The antiallergic effects and acute toxicity of Lactobacillus crispatus KT-11 cultured in food grade medium

We synthesized a medium consisting of commercial food supplements (food grade medium) that could be used to cultivate Lactobacillus crispatus KT-11 (KT-11), and investigated the antiallergic effects and acute toxicity of KT-11 cultured in this medium. We found that the growth of KT-11 in the food grade medium was comparable to that in DeMan-Rogosa-Sharpe (MRS) medium. Sneezing event was reduced in ovalbumin (OVA)-sensitized BALB/c mice given a diet supplemented with KT-11 grown in the food grade medium (FG-KT-11 group) when compared to mice given a diet supplemented with KT-11 grown in MRS medium (MRS-KT-11 group). The number of CD80(+)CD11b(+) Peyer's patch cells was significantly lower in the FG-KT-11 group than in the MRS-KT-11 group, while IL-12(+)CD11b(+) Peyer's patch cells were higher in the FG-KT-11 group. Only minimal acute toxicity was observed in ICR mice given 1000 or 2000 mg of FG-KT-11/kg body weight. These results suggest that FG-KT-11 represents a safe antiallergic food material.

[Morphological changes in lymphoid nodules of small intestine in dehydration]

Morphological, cytological, morphometric changes were studied in single lymphoid nodules and in grouped lymphoid nodules (Peyers patches) of small intestine in albino rats after the dehydration lasting 3, 6, and 10 days and correction by administration of sodium chloride isotonic solution. In was found that the dehydration resulted in the decrease of lymphoid nodule dimensions, changes in the cellular proportions, enlargement of reticular fiber loops in the nodule stroma. On days 6 and 10 of dehydration, the percentages of macrophages, lymphocytes, cells showing the mitotic figures, mast cells and plasma cells were significantly decreased by factor of 1,4-4, indicating a depression of immune reactions.

Polyclonal B cell differentiation and loss of gastrointestinal tract germinal centers in the earliest stages of HIV-1 infection

BACKGROUND

The antibody response to HIV-1 does not appear in the plasma until approximately 2-5 weeks after transmission, and neutralizing antibodies to autologous HIV-1 generally do not become detectable until 12 weeks or more after transmission. Moreover, levels of HIV-1-specific antibodies decline on antiretroviral treatment. The mechanisms of this delay in the appearance of anti-HIV-1 antibodies and of their subsequent rapid decline are not known. While the effect of HIV-1 on depletion of gut CD4(+) T cells in acute HIV-1 infection is well described, we studied blood and tissue B cells soon after infection to determine the effect of early HIV-1 on these cells.

METHODS AND FINDINGS

In human participants, we analyzed B cells in blood as early as 17 days after HIV-1 infection, and in terminal ileum inductive and effector microenvironments beginning at 47 days after infection. We found that HIV-1 infection rapidly induced polyclonal activation and terminal differentiation of B cells in blood and in gut-associated lymphoid tissue (GALT) B cells. The specificities of antibodies produced by GALT memory B cells in acute HIV-1 infection (AHI) included not only HIV-1-specific antibodies, but also influenza-specific and autoreactive antibodies, indicating very early onset of HIV-1-induced polyclonal B cell activation. Follicular damage or germinal center loss in terminal ileum Peyer's patches was seen with 88% of follicles exhibiting B or T cell apoptosis and follicular lysis.

CONCLUSIONS

Early induction of polyclonal B cell differentiation, coupled with follicular damage and germinal center loss soon after HIV-1 infection, may explain both the high rate of decline in HIV-1-induced antibody responses and the delay in plasma antibody responses to HIV-1. Please see later in the article for Editors' Summary.

Soybean protein fraction digested with neutral protease preparation, "Peptidase R", produced by Rhizopus oryzae, stimulates innate cellular immune system in mouse

A soybean protein fraction was prepared from defatted soybean seed flour and digested with 29 kinds of commercially available protease originating from preparations of animals, plants, and microorganisms. Some digests, in particular, Ro-digest prepared using a Rhizopus oryzae neutral protease preparation (Peptidase R), displayed strong mitogenic activity toward C3H/HeN mouse spleen cells. The number of spleen CD11b+, CD49b+, interleukin (IL)-12+CD11b+, and interferon (IFN)-gamma+CD49b+ cells significantly increased when cultured with Ro-digest. Similarly, the number of spleen IFN-gamma+CD4+ cells significantly increased in the presence of Ro-digest while that of spleen IL-4+CD4+ cells was largely unchanged. Additionally, 5-week-old male C3H/HeN mice were given diets consisting of ovalbumin (OVA) alone (control diet) or a mixture of OVA and Ro-digest (Ro-digest-added diet) as a protein source for 5 weeks, and the immune properties of the mice were investigated. The number of IL-12+CD11b+ cells was greater in spleens from mice given the Ro-digest-added diet than in those given the control diet. The cytotoxic activity of spleen cells toward the human erythroleukemia cell line, K562, was significantly higher in mice given the Ro-digest-added diet than in those given the control diet. Furthermore, in a microarray analysis of mRNAs extracted from mice Peyer's patch cells, gene expression related to innate immune responses was increased in mice given the Ro-digest-added diet. These results indicate that the Ro-digest might stimulate cellular immune systems, in particular, an innate immunity in mice.

[The influence of hypoxia inducible factor-1 alpha expression on apoptosis and proliferation of T lymphocyte in the Peyer's patches after burn with delayed fluid resuscitation in rats at high altitude]

OBJECTIVE

To explore the influence of hypoxia inducible factor-1 alpha (HIF-1 alpha) expression on the apoptosis and proliferation of T lymphocyte after severe burn with delayed fluid resuscitation at different altitude in rats.

METHODS

One hundred and thirty-two Wistar rats were subjected to burn injury [30% total body surface area (TBSA), III degree], at 1,517 metres and 3,848 metres above sea level, and they were randomly divided into three groups: delayed fluid resuscitation group (DFR, n=30 at each altitude), immediate fluid resuscitation group (IFR, n=30 at each altitude), and sham group (SG, n=6). The Peyer's patches were harvested from the ileum of rats at 6, 12, 24, 48 and 72 hours after burn respectively. The levels of HIF-1 alpha, CD3(+) and the rate of apoptosis in Peyer's patches were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), tissue microarray technology and immunohistochemistry.

RESULTS

The apoptosis rate in Peyer's patches was higher in DFR group than that in IFR group. The increase in HIF-1 alpha expression was observed mainly on cell nucleus in T lymphocytes. The expression levels of HIF-1 alpha in Peyer's patches were much higher in DFR group and IFR group than those in SG, and they were higher at 3 848 metres than those at 1 517 metres, and also higher in DFR group compared with IFR group (all P<0.05). The decrease in CD3(+) expression was observed mainly on cell membrane in T lymphocytes. The expression levels of CD3(+) in Peyer's patches were much higher in DFR group and IFR group than those in SG group, and the trough value appeared at 12 hours after burn (all P<0.05).

CONCLUSION

High expression of HIF-1 alpha may be responsible for the high apoptosis rate and decrease of T lymphocyte number in Peyer's patches after severe burn with delayed fluid resuscitation in rats at high altitude.

CD83+CCR7- dendritic cells accumulate in the subepithelial dome and internalize translocated Escherichia coli HB101 in the Peyer's patches of ileal Crohn's disease

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.

Eosinophil-nerve interactions and neuronal plasticity in rat gut associated lymphoid tissue (GALT) in response to enteric parasitism

Intestinal lymphoid tissues and Peyer's patches (PP) are innervated sites of immune surveillance in the gastrointestinal tract. Following infection with F. hepatica, neuronal hyperplasia and significantly increased eosinophil and mast cell trafficking to colonic PP sites were evident in rat tissues. Nerve-eosinophil associations were significantly elevated in infected colon and colonic PP, as were colonic tissue levels of the circulatory recruitment factors IL-5 and eotaxin. Increased immunoreactivity for neuronal plasticity markers GAP-43 and neural cell adhesion molecule (NCAM) was also found in infected tissues. Such neuronal alterations in the PP during enteric parasitism may have functional consequences on particular or pathogen uptake.

[Effects of Huoxiang Zhengqi liquid on enteric mucosal immune responses in mice with Bacillus dysenteriae and Salmonella typhimurium induced diarrhea]

OBJECTIVE

To explore the effects of Huoxiang Zhengqi liquid (HXZQ) on enteric mucosal immune responses in mice with Bacillus dysenteriae and Salmonella typhimurium induced diarrhea (BSD).

METHOD

Mice were randomly divided into four groups with 10 mice in each group: control group (control), BSD group, Huoxiang Zhengqi liquid treated BSD groups at high dosage and low dosage (HXZQ high, HXZQ low). HXZQ was administrated from the day of diarrhea induction at dosage of 5.21 g kg(-1) and 0.52 g kg (-1) respectively. Peyer's patch and periphery lymphocytes were prepared for flow cytometry, and level of TNF-alpha in periphery and enteric tissue homogenate were determined with ELISA. Student's t-test was used for statistics.

RESULT

Mice in BSD group started showing continuous diarrhea at the day of induction till the fourth day when the mice were sacrificed. Diarrhea in the mice of HXZQ high and low groups lasted for 36 and 54 h respectively. There were more CD4+ and CD8+ cells in periphery, less CD4+ cells in peyer's patch in BSD mice comparing to normal mice. In peyer's patch, there were more CD8+ cells in mice in HXZQ high and low groups and more CD4+ in mice in HXZQ high group. Higher level TNF-alpha in periphery and intestinal tissue homogenate in BSD group were observed. Mice in HXZQ high group showed the decreased level TNF-alpha in periphery and enteric tissue homogenate.

CONCLUSION

The immune regulation on peyer's patch CD4+ and CD8+ cells and suppression on TNF-alpha level in enteric homogenate might partially explain the effect of HXZQ on improvement of BSD.

Primary involvement of pharynx and peyer's patch in inhalational and intestinal anthrax

Bacillus anthracis causes three forms of anthrax: inhalational, gastrointestinal, and cutaneous. Anthrax is characterized by both toxemia, which is caused by secretion of immunomodulating toxins (lethal toxin and edema toxin), and septicemia, which is associated with bacterial encapsulation. Here we report that, contrary to the current view of B. anthracis pathogenesis, B. anthracis spores germinate and establish infections at the initial site of inoculation in both inhalational and cutaneous infections without needing to be transported to draining lymph nodes, and that inhaled spores establish initial infection in nasal-associated lymphoid tissues. Furthermore, we found that Peyer's patches in the mouse intestine are the primary site of bacterial growth after intragastric inoculation, thus establishing an animal model of gastrointestinal anthrax. All routes of infection progressed to the draining lymph nodes, spleen, lungs, and ultimately the blood. These discoveries were made possible through the development of a novel dynamic mouse model of B. anthracis infection using bioluminescent non-toxinogenic capsulated bacteria that can be visualized within the mouse in real-time, and demonstrate the value of in vivo imaging in the analysis of B. anthracis infection. Our data imply that previously unrecognized portals of bacterial entry demand more intensive investigation, and will significantly transform the current perception of inhalational, gastrointestinal, and cutaneous B. anthracis pathogenesis.

Anthrax is caused by Bacillus anthracis, a bacterial pathogen that forms spores, dormant bacteria that are highly resistant to destruction. Infections initiate from the introduction of spores into airways or damaged skin, or from the consumption of contaminated food. Within the host, spores germinate, then bacteria secrete toxins that cripple the immune response and sheath themselves in a capsule that prevents them from being phagocytosed. We strove to determine in real space and time where and when spores introduced by these three routes of infection germinate and how bacteria subsequently disseminate in a mouse model. This was achieved through the development of light-emitting B. anthracis that could be tracked inside a living mouse. Contrary to current models, our studies indicated that spores germinated in situ in the skin, the intestines, and the nasal passages without needing to be transported to lymph nodes. Furthermore, bacteria disseminate from initial sites of infection in a similar fashion, first to the draining lymph nodes, then the spleen, and finally the lungs and blood. These findings imply that spore interactions with local sites of entry are critical in the development of systemic disease and that disruption of these interactions may offer new methods of anthrax prevention.

IFN-gamma-producing dendritic cells are important for priming of gut intraepithelial lymphocyte response against intracellular parasitic infection

The importance of intraepithelial lymphocytes (IEL) in immunoprotection against orally acquired pathogens is being increasingly recognized. Recent studies have demonstrated that Ag-specific IEL can be generated and can provide an important first line of defense against pathogens acquired via oral route. However, the mechanism involved in priming of IEL remains elusive. Our current study, using a microsporidial model of infection, demonstrates that priming of IEL is dependent on IFN-gamma-producing dendritic cells (DC) from mucosal sites. DC from mice lacking the IFN-gamma gene are unable to prime IEL, resulting in failure of these cells to proliferate and lyse pathogen-infected targets. Also, treatment of wild-type DC from Peyer's patches with Ab to IFN-gamma abrogates their ability to prime an IEL response against Encephalitozoon cuniculi in vitro. Moreover, when incubated with activated DC from IFN-gamma knockout mice, splenic CD8(+) T cells are not primed efficiently and exhibit reduced ability to home to the gut compartment. These data strongly suggest that IFN-gamma-producing DC from mucosal sites play an important role in the generation of an Ag-specific IEL response in the small intestine. To our knowledge, this report is the first demonstrating a role for IFN-gamma-producing DC from Peyer's patches in the development of Ag-specific IEL population and their trafficking to the gut epithelium.

Interaction between dendritic cells and nerve fibres in lymphoid organs after oral scrapie exposure

In transmissible spongiform encephalopathies (TSEs), the infectious agent, called PrPsc, an abnormal isoform of the cellular prion protein, accumulates and replicates in lymphoid organs before affecting the nervous system. To clarify the cellular requirements for the neuroinvasion of the scrapie agent from the lymphoid organs to the central nervous system, we have studied, by confocal microscopy, the innervations within Peyer's patches, mesenteric lymph nodes and the spleen of mice in physiological conditions and after oral exposure to prion. Contacts between nerve fibres and PrPsc-associated cells, dendritic cells (DCs) and follicular dendritic cells (FDCs), were evaluated in preclinical prion-infected mice. Using a double immunolabelling strategy, we demonstrated the lack of innervation of PrPsc-accumulating cells (FDCs). Contacts between nerve fibers and PrPsc-propagating cells (DCs) were detected in T-cell zones and cell-trafficking areas. This supports, for the first time, the possible implication of dendritic cells in the prion neuroinvasion process.

Oral scrapie infection modifies the homeostasis of Peyer's patches' dendritic cells

In transmitted prion diseases the immune system supports the replication and the propagation of the pathogenic agent (PrPSc). DCs, which are mobile cells present in large numbers within lymph organs, are suspected to carry prions through the lymphoid system and to transfer them towards the peripheral nervous system. In this study, C57Bl/6 mice were orally inoculated with PrPSc (scrapie strain 139A) and sacrificed at the preclinical stages of the disease. Immunolabelled cryosections of Peyer's patches were analysed by confocal microscopy. Membrane prion protein expression was studied by flow cytometry. In Peyer's patches (PP), dissected at day one and day 105 after oral exposure to scrapie, we observed an increased population of DCs localised in the follicular-associated epithelium. On day 105, PrPSc was found in the follicles inside the PP of prion-infected mice. A subset of Peyer's patches DCs, which did not express cellular prion protein on their surface in non-infected mice conditions, was prion-positive in scrapie conditions. Within Peyer's patches oral scrapie exposure thus induced modifications of the homeostasis of DCs at the preclinical stages of the disease. These results give new arguments in favour of the implication of DCs in prion diseases.

Can a failed ileal pouch anal anastomosis be left in situ?

OBJECTIVE

Failure after ileal pouch-anal anastomosis (IPAA) is reported with a frequency of 10-20%. The failed IPAA can be excised or defunctioned. Indications for excision and further management of an indefinitely diverted pouch are poorly described. The aim of the present investigation was to investigate pouch-related problems and the histopathological pattern of the pouch mucosa in this group of patients.

METHOD

In a cohort of 620 patients having IPAA with a median follow-up of 14 years, 56 patients with failure were identified. The patients with defunctioned pouches were assessed with regard to pouch-related problems and endoscopy with biopsies was performed. Biopsies were stained with haematoxylin-eosin, PAS for neutral mucins and Alcian blue/high iron diamine for sialomucins/sulphomucins. Morphological changes were grouped into three types modified according to Veress and assessed for dysplasia.

RESULTS

Twenty-two patients with an indefinitely diverted pouch were found. The follow-up time after surgery for failure was 10 years. Thirteen patients completed the follow-up. Except for two patients with pelvic/perineal pain, there were no clinical problems. The majority of patients displayed mild to moderate macroscopic signs of inflammation. Morphologically, findings ranged from a preserved mucosal pattern to intense inflammatory reaction. No case of dysplasia or carcinoma was found.

CONCLUSION

Most patients with an indefinitely diverted pouch had no complaints regarding the pouch. There was no case of dysplasia. Indefinite diversion may be preferable to pouch excision, especially given the associated morbidity.

Bis(tributyltin)oxide (TBTO) decreases the food allergic response against peanut and ovalbumin in Brown Norway rats

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 10mg 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.

CARD15/NOD2 is required for Peyer's patches homeostasis in mice

Background

CARD15/NOD2 mutations are associated with susceptibility to Crohn's Disease (CD) and Graft Versus Host Disease (GVHD). CD and GVHD are suspected to be related with the dysfunction of Peyer's patches (PP) and isolated lymphoid follicles (LFs). Using a new mouse model invalidated for Card15/Nod2 (KO), we thus analysed the impact of the gene in these lymphoid formations together with the development of experimental colitis.

Methodology/Principal Findings

At weeks 4, 12 and 52, the numbers of PPs and LFs were higher in KO mice while no difference was observed at birth. At weeks 4 and 12, the size and cellular composition of PPs were analysed by flow cytometry and immunohistochemistry. PPs of KO mice were larger with an increased proportion of M cells and CD4⁺ T-cells. KO mice were also characterised by higher concentrations of TNFα, IFNγ, IL12 and IL4 measured by ELISA. In contrast, little differences were found in the PP-free ileum and the spleen of KO mice. By Ussing chamber experiments, we found that this PP phenotype is associated with an increased of both paracellular permeability and yeast/bacterial translocation. Finally, KO mice were more susceptible to the colitis induced by TNBS.

Conclusions

Card15/Nod2 deficiency induces an abnormal development and function of the PPs characterised by an exaggerated immune response and an increased permeability. These observations provide a comprehensive link between the molecular defect and the Human CARD15/NOD2 associated disorders: CD and GVHD.

Role of the GALT in scrapie agent neuroinvasion from the intestine

Following oral exposure, some transmissible spongiform encephalopathy (TSE) agents accumulate first upon follicular dendritic cells (FDCs) in the GALT. Studies in mice have shown that this accumulation is obligatory for the efficient delivery of the TSE agent to the brain. However, which GALTs are crucial for disease pathogenesis is uncertain. Mice deficient in specific GALT components were used here to determine their separate involvement in scrapie agent neuroinvasion from the intestine. In the combined absence of the GALTs and FDCs (lymphotoxin (LT)alpha(-/-) mice and LTbeta(-/-) mice), scrapie agent transmission was blocked. When FDC maturation was induced in remaining lymphoid tissues, mice that lacked both Peyer's patches (PPs) and mesenteric lymph nodes (wild-type (WT)-->LTalpha(-/-) mice) or PPs alone (WT-->LTbeta(-/-) mice) remained refractory to disease, demonstrating an important role for the PPs. Although early scrapie agent accumulation also occurs within the mesenteric lymph nodes, their presence in WT-->LTbeta(-/-) mice did not restore disease susceptibility. We have also shown that isolated lymphoid follicles (ILFs) are important novel sites of TSE agent accumulation in the intestine. Mice that lacked PPs but contained numerous FDC-containing mature ILFs succumbed to scrapie at similar times to control mice. Because the formation and maturation status of ILFs is inducible and influenced by the gut flora, our data suggest that such factors could dramatically affect susceptibility to orally acquired TSE agents. In conclusion, these data demonstrate that following oral exposure TSE agent accumulation upon FDCs within lymphoid tissue within the intestine itself is critically required for efficient neuroinvasion.

Germinal center architecture disturbance during Plasmodium berghei ANKA infection in CBA mice

Background

Immune responses to malaria blood stage infection are in general defective, with the need for long-term exposure to the parasite to achieve immunity, and with the development of immunopathology states such as cerebral malaria in many cases. One of the potential reasons for the difficulty in developing protective immunity is the poor development of memory responses. In this paper, the potential association of cellular reactivity in lymphoid organs (spleen, lymph nodes and Peyer's patches) with immunity and pathology was evaluated during Plasmodium berghei ANKA infection in CBA mice.

Methods

CBA mice were infected with 1 × 10⁶ P. berghei ANKA-parasitized erythrocytes and killed on days 3, 6–8 and 10 of infection. The spleen, lymph nodes and Peyer's patches were collected, fixed in Carson's formalin, cut in 5 μm sections, mounted in glass slides, stained with Lennert's Giemsa and haematoxylin-eosin and analysed with bright-field microscopy.

Results

Early (day 3) strong activation of T cells in secondary lymphoid organs was observed and, on days 6–8 of infection, there was overwhelming activation of B cells, with loss of conventional germinal center architecture, intense centroblast activation, proliferation and apoptosis but little differentiation to centrocytes. In the spleen, the marginal zone disappeared and the limits between the disorganized germinal center and the red pulp were blurred. Intense plasmacytogenesis was observed in the T cell zone.

Conclusion

The observed alterations, especially the germinal center architecture disturbance (GCAD) with poor centrocyte differentiation, suggest that B cell responses during P. berghei ANKA infection in mice are defective, with potential impact on B cell memory responses.

Neuroimmune connections in jejunal and ileal Peyer’s patches at various bovine ages: potential sites for prion neuroinvasion

During preclinical stages of cattle orally infected with bovine spongiform encephalopathy (BSE), the responsible agent is confined to ileal Peyer's patches (IPP), namely in nerve fibers and in lymph follicles, before reaching the peripheral and central nervous systems. No infectivity has been reported in other bovine lymphoid organs, including jejunal Peyer's patches (JPP). To determine the potential sites for prion neuroinvasion in IPP, we analyzed the mucosal innervation and the interface between nerve fibers and follicular dendritic cells (FDC), two dramatic influences on neuroinvasion. Bovine IPP were studied at three ages, viz., newborn calves, calves less than 12 months old, and bovines older than 24 months, and the parameters obtained were compared with those of JPP. No differences in innervation patterns between IPP and JPP were found. The major difference observed was that, in calves of less than 12 months, IPP were the major mucosal-associated lymphoid organ that possessed a large number of follicles with extended FDC networks. Using a panel of antibodies, we showed that PP in 24-month-old bovines were highly innervated at various strategic sites assumed to be involved in the invasion and replication of the BSE pathogen: the suprafollicular dome, T cell area, and germinal centers. In PP in calves of less than 12 months old, no nerve fibers positive for the neurofilament markers NF-L (70 kDa) and NF-H (200 kDa) were observed in contact with FDC. Thus, in view of the proportion of these protein subunits present in neurofilaments, the innervation of the germinal centers can be said to be an age-dependent dynamic process. This variation in innervation might influence the path of neuroinvasion and, thus, the susceptibility of bovines to the BSE agent.

Primary gastrointestinal tract lymphoma: diagnosis and management of common neoplasms

Primary gastrointestinal lymphoma represents the most common location of extranodal lymphoma. With the bulk of disease manifesting within the gastrointestinal tract and contiguous lymph nodes, many of the lymphomas occurring in the peripheral lymph nodes can also present with primary gastrointestinal tract involvement. Molecular biology has recently enabled significant progress in the diagnosis and management of primary gastrointestinal lymphoma. Herein, we will discuss the major lymphomas affecting the bowel and highlight their key morphological, immunophenotypical and molecular diagnostic attributes. Similarly, in keeping with recent therapeutic advances, we will briefly discuss some important treatment considerations. Thus, this review is intended to offer clinicians and pathologists an overview of primary gastrointestinal lymphomas.

Adaptation of solitary intestinal lymphoid tissue in response to microbiota and chemokine receptor CCR7 signaling

Besides Peyer's patches, solitary intestinal lymphoid tissue (SILT) provides a structural platform to efficiently initiate immune responses in the murine small intestine. SILT consists of dynamic lymphoid aggregates that are heterogeneous in size and composition, ranging from small clusters of mostly lineage-negative cells known as cryptopatches to larger isolated lymphoid follicles rich in B cells. In this study, we report that in chemokine receptor CCR7-deficient mice SILT is enlarged, although unchanged in frequency and cellular composition compared with wild-type mice. This phenotype is conferred by bone marrow-derived cells and is independent of the presence of intestinal bacteria. Remarkably, particularly small-sized SILT predominates in germfree wild-type mice. Colonization of wild-type mice with commensal bacteria provokes an adjustment of the spectrum of SILT to that observed under specific pathogen-free conditions by the conversion of pre-existing lymphoid structures into larger-sized SILT. In conclusion, our findings establish that intestinal microbes influence the manifestation of gut-associated lymphoid tissues and identify CCR7 signaling as an endogeneous factor that controls this process.

[Changes in the aggregated lymphoid nodules and in the mesenterial lymph nodes of rats after the administration of a chemotherapeutic drug complex: response similarities and differences]

Changes in the structure and cellular composition of aggregated lymphoid nodules (ALN, Peyer's patches) of the small intestine and in mesenterial lymph nodes (MLN) were studied in 82 female Wistar rats 7, 14 and 21 days following a single intraperitoneal injection of a complex of antineoplastic drugs (cyclophosphamide, adriamycine, vincristine and prednisolone). In ALN and MLN lymphoid nodules the administration of antineoplastic drugs resulted in the decrease of the number of blast cells and mitotically dividing cells, suggesting the suppression of B-cell proliferation and differentiation. At the same time, the dimensions of germinal centers in ALN lymphoid nodules were reduced, while their mantle zone size remained unchanged. On the contrary, in MLN lymphoid nodules, mantle zone was reduced, while germinal center dimensions remained constant. Possible reasons of these differences in responses of the immune organs studied to chemotherapy, are discussed.

Immunohistochemical characterization of cell types expressing the cellular prion protein in the small intestine of cattle and mice

The gastrointestinal tract is thought to be the main site of entry for the pathological isoform of the prion protein (PrP(Sc)). Prion diseases are believed to result from a conformational change of the cellular prion protein (PrP(c)) to PrP(Sc). Therefore, PrP(c) expression is a prerequisite for the infection and spread of the disease to the central nervous system. However, the distribution of PrP(c) in the gut is still a matter of controversy. We therefore investigated the localization of PrP(c) in the bovine and murine small intestine. In cattle, most PrP(c) positive epithelial cells were detected in the duodenum, while a few positive cells were found in the jejunum. PrP(c) was expressed in serotonin producing cells. In bovine Peyer's patches, PrP(c) was distributed in extrafollicular areas, but not in the germinal centre of the jejunum and ileum. PrP(c) was expressed in myeloid lineage cells such as myeloid dendritic cells and macrophages. In mice, PrP(c) was expressed in some epithelial cells throughout the small intestine as well as in cells such as follicular dendritic cell in the germinal centre of Peyer's patches. In this study, we demonstrate that there are a number of differences in the localization of PrP(c) between the murine and bovine small intestines.

Effect of FTY720 in Rat Small Bowel Transplantation: Apoptosis of Crypt Cells and Lymphocytes in Gut-Associated Lymphoid Tissues

AIM

We investigated the extent of apoptosis in crypt cells and Peyer's patches (PPs) during small bowel allograft rejection in rats to examine the effect of FTY720 during rejection.

METHODS

Orthotopic small bowel transplantations (SBTs) were performed from BN to LEW rats. Isografted animals served as controls. Three groups of SBT animals were studied on days 3, 5, and 7 after operation: isograft, untreated allograft, allograft with FTY720. FTY720 was orally administered by gavage (1 mg/kg/d) to allograft recipients on 7 consecutive days. Cryostat sections were prepared from grafts, including PPs. An in situ end-labeling (ISEL) technique was used to detect apoptotic cells. Indirect immunoperoxidase staining was also performed using monoclonal antibodies against rat Fas/Fas-L.

RESULTS

Graft survival was prolonged in the FTY720-treated group. The number of ISEL-positive enterocytes in the allografts increased significantly on days 3, 5, and 7 compared with the isograft group. In the FTY720-treated group, the number of ISEL-positive enterocytes in the allografts was down-regulated significantly on days 3, 5, and 7 compared with untreated allograft group. In the PPs, the number of ISEL-positive mononuclear cells increased significantly in the allografts compared with the isograft group. In the FTY720-treated groups, the number of ISEL-positive mononuclear cells were down-regulated significantly in the allografts compared with the untreated allograft group. The number of Fas/FasL-positive enterocytes were increased significantly in allografts compared with isograft group. In FTY720-treated groups, the number of Fas/FasL-positive enterocytes were down-regulated significantly on day 7 compared with the untreated allograft group. In the PPs, Fas/FasL-positive mononuclear cells also increased significantly on day 7 in the allografts compared with isografts. In the FTY720-treated groups, Fas/FasL-positive mononuclear cells were down-regulated significantly in the allografts compared with the untreated allograft group.

CONCLUSIONS

The number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes increased during small bowel graft rejection. FTY720 prevented up-regulation of the number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes while also prolonging small bowel allograft survival.

Absorption, accumulation and biological effects of depleted uranium in Peyer's patches of rats

The digestive tract is the entry route for radionuclides following the ingestion of contaminated food and/or water wells. It was recently characterized that the small intestine was the main area of uranium absorption throughout the gastrointestinal tract. This study was designed to determine the role played by the Peyer's patches in the intestinal absorption of uranium, as well as the possible accumulation of this radionuclide in lymphoid follicles and the toxicological or pathological consequences on the Peyer's patch function subsequent to the passage and/or accumulation of uranium. Results of experiments performed in Ussing chambers indicate that the apparent permeability to uranium in the intestine was higher (10-fold) in the mucosa than in Peyer's patches ((6.21+/-1.21 to 0.55+/-0.35)x10(-6)cm/s, respectively), demonstrating that the small intestinal epithelium was the preferential pathway for the transmucosal passage of uranium. A quantitative analysis of uranium by ICP-MS following chronic contamination with depleted uranium during 3 or 9 months showed a preferential accumulation of uranium in Peyer's patches (1355% and 1266%, respectively, at 3 and 9 months) as compared with epithelium (890% and 747%, respectively, at 3 and 9 months). Uranium was also detected in the mesenteric lymph nodes ( approximately 5-fold after contamination with DU). The biological effects of this accumulation of depleted uranium after chronic contamination were investigated in Peyer's patches. There was no induction of the apoptosis pathway after chronic DU contamination in Peyer's patches. The results indicate no change in the cytokine expression (Il-10, TGF-beta, IFN-gamma, TNF-alpha, MCP-1) in Peyer's patches and in mesenteric lymph nodes, and no modification in the uptake of yeast cells by Peyer's patches. In conclusion, this study shows that the Peyer's patches were a site of retention for uranium following the chronic ingestion of this radionuclide, without any biological consequences of such accumulation on Peyer's patch functions.

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in mice

Mice (n=20) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 18-59 days post-infection (dpi), except for two mice that died at 6 and 32 dpi, and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical examination. Apart from the two deaths, the experimental infection was inapparent, but virus was invariably recovered from faeces and several organs. The main histopathological lesions were focal interstitial pancreatitis, depletion of thymus and Peyer's patches, and interstitial pneumonia. Additionally, in the two mice that died, multifocal interstitial myocarditis was observed. EMCV antigen was detected in the cytoplasm of pancreatic acinar cells and in macrophages of the lung and the thymus. Antigen was also detected in the cytoplasm of cardiac muscle cells from three animals, including the two that died. The results support the role of mice, in addition to rats, as reservoir hosts in the epidemiology of EMCV infections on pig farms.