The mucosal immune system: from specialized immune defense to inflammation and allergy

Mucosal vaccination: onward and upward

INTRODUCTION

The unique mucosal immune system allows the generation of robust protective immune responses at the front line of pathogen encounters. The needle-free delivery route and cold chain-free logistic requirements also provide additional advantages in ease and economy. However, the development of mucosal vaccines faces several challenges, and only a handful of mucosal vaccines are currently licensed. These vaccines are all in the form of live attenuated or inactivated whole organisms, whereas no subunit-based mucosal vaccine is available.

AREAS COVERED

The selection of antigen, delivery vehicle, route and adjuvants for mucosal vaccination are highly important. This is particularly crucial for subunit vaccines, as they often fail to elicit strong immune responses. Emerging research is providing new insights into the biological and immunological uniqueness of mucosal tissues. However, many aspects of the mucosal immunology still await to be investigated.

EXPERT OPINION

This article provides an overview of the current understanding of mucosal vaccination and discusses the remaining knowledge gaps. We emphasize that because of the potential benefits mucosal vaccines can bring from the biomedical, social and economic standpoints, the unmet goal to achieve mucosal vaccine success is worth the effort.

Intermittent antibiotic treatment accelerated the development of colitis in IL-10 knockout mice

BACKGROUND AND AIMS

Many epidemiological studies suggest an association between antibiotic exposure and the development of inflammatory bowel disease [IBD]. However, the majority of these studies are observational and still the question remains, "Does the specific antibiotic administration regimen play a role in the development of colitis?" This study aimed to compare the possible effects of continuous and intermittent antibiotic exposure on the development of colitis using a colitis-susceptible IL-10 knockout [IL-10-/-] mouse model.

METHODS

IL-10-/- mice [C57BL/6] were randomly assigned to a non-antibiotic group, continuous antibiotic group and intermittent antibiotic group, and observed for 30 weeks. The antibiotic cocktail was given via the drinking water. The differential response to antibiotics was assessed.

RESULTS

Intermittent antibiotic treatment resulted in severe colitis with early disease onset in IL-10-/- mice. Higher unit colon weight and spleen weight were observed in intermittent antibiotic-treated mice but not in the continuous antibiotic group. Moreover, intermittent antibiotic treatment aggravated epithelial damage and colonic inflammation, mucosal barrier dysfunction and colonic allergic sensitization in IL-10-/- mice, whereas continuous antibiotic treatment ameliorated these symptoms. Male IL-10-/- mice with intermittent antibiotic exposure were more susceptible to colonic inflammation and allergic response than females.

CONCLUSIONS

In summary, intermittent antibiotic exposure accelerated the development of severe colitis more than continuous antibiotic exposure in IL-10-/- male mice. In addition to the colonic damage and impaired barrier function, stimulation of allergic response may play a role in accelerating the development of colitis in genetically susceptible mice.

Dietary supplementation with spray-dried porcine plasma has prebiotic effects on gut microbiota in mice

In animal models of inflammation and in farm animals, dietary inclusion of spray-dried porcine plasma (SDP) reduces mucosal inflammation. Here, we study whether these effects could be mediated by changes in the intestinal microbiota and if these changes are similar to those induced by oral antibiotics. Weaned 21-day-old C57BL/6 mice were divided into 3 groups: the CTL group, fed the control diet; the COL group, administered low doses of neomycin and colistin; and the SDP group, supplemented with 8% SDP. After 14 days, analysis of the fecal microbiome showed that the microbiota profiles induced by SDP and the antibiotics were very different, thus, SDP has prebiotic rather than antibiotic effects. At the phylum level, SDP stimulated the presence of Firmicutes, considerably increasing the lactobacilli population. It also enhanced the growth of species involved in regulatory T-lymphocyte homeostasis and restoration of the mucosal barrier, as well as species negatively correlated with expression of pro-inflammatory cytokines. At the mucosal level, expression of toll-like receptors Tlr2, Tlr4 and Tlr9, and mucous-related genes Muc2 and Tff3 with regulatory and barrier stability functions, were increased. SDP also increased expression of Il-10 and Tgf-β, as well as markers of macrophages and dendritic cells eventually promoting an immune-tolerant environment.

Ameliorative effect of Alnus japonica ethanol extract on colitis through the inhibition of inflammatory responses and attenuation of intestinal barrier disruption in vivo and in vitro

Inflammatory bowel disease (IBD) is chronic inflammation of the gastrointestinal tract caused by high levels of pro-inflammatory cytokines and epithelial barrier dysfunction. Alnus japonica Steud. (Betulaceae) has been used in traditional Asian medicine. However, the potential of A. japonica for the treatment of intestinal inflammation has not been investigated. This study investigated the effects of ethanol extract from A. japonica bark (AJE) on colonic mucosa injury in mice with dextran sodium sulfate (DSS)-induced colitis. Treatment with AJE ameliorated pathological damage and the histopathologic features of DSS-induced colitis. The administration of AJE also inhibits DSS-induced pro-inflammatory cytokines expression, including interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and cyclooxygenase (COX)-2. Notably, AJE administration attenuated the reduction of tight junction proteins, zonula occludens (ZO)-1 and occludin, in DSS-induced colitis. In addition, AJE increased heme oxygenase (HO)-1 expression and prevented DSS-induced apoptosis in colonic epithelial cells. Furthermore, in vitro studies demonstrated that AJE inhibits TNF-α-induced IL-8, IL-1β, and COX-2 expression in human intestinal epithelial HT-29 cells and tert-butyl hydroperoxide-induced reduction of ZO-1 and occludin expression in human intestinal epithelial Caco-2 cells. AJE-induced HO-1 protein expression was also found in both HT-29 and Caco-2 cells. Taken together, our findings demonstrated that AJE inhibits intestinal inflammation and protects against intestinal barrier disruption in mice with DSS-induced colitis in vivo and human intestinal epithelial cells in vitro. These results suggest that AJE might have beneficial effects for the treatment of IBD.

Pulmonary vaccine delivery

This review will discuss developments in the field of pulmonary vaccine delivery. The possibilities of adopting aerosol-generation technology and specific pharmaceutical formulations for the purpose of pulmonary immunization are described. Aerosol-generation systems might offer advantages with respect to vaccine stability and antigenicity. Adjuvants and their inclusion in vaccine-delivery systems are described. Other formulation components, such as surfactants, particulate systems and dispersion of the aerosols are detailed in this paper. The noninvasive, relatively safe and low-cost nature of pulmonary delivery may provide great benefits to the public health vaccination campaign.

Melatonin reduces bacterial translocation by preventing damage to the intestinal mucosa in an experimental severe acute pancreatitis rat model

Recent studies have demonstrated that melatonin significantly decreased all studied acute pancreatitis-associated inflammatory parameters, in addition to reducing apoptosis and necrosis associated with pancreatic injury. However, the effect of melatonin on gut barrier dysfunction and bacterial translocation has not been fully elucidated. This study aimed to investigate the protective effects of melatonin on intestinal integrity in a rat model of severe acute pancreatitis (SAP) to evaluate whether melatonin prevented intestine barrier dysfunction and reduced bacterial translocation. Forty male Sprague Dawley (SD) rats were randomly divided into three groups, with 8 rats in the sham operation (SO) group, 18 rats in the SAP group and 14 SAP rats in the melatonin treatment (MT) group. SAP was induced by retrograde injection of 4% taurocholate into the biliopancreatic duct. Melatonin was administered 30 min prior to taurocholate injection in the melatonin-treated rats. All rats were sacrificed 24 h subsequent to pancreatitis induction. Real-time fluorescence quantitative polymerase chain reaction was used to detect and quantify Escherichia coli (E. coli) O157 in postcava blood. The microvilli structure was also analyzed with transmission electron microscopy. The level of E. coli DNA in the MT group was significantly lower than in rats in the SAP group. No E. coli DNA was detected in the control group. Villus height and crypt depth in the ileum were significantly higher in the MT and control groups compared to the SAP group, and were significantly higher in the MT group than in the SAP group. These results suggested that melatonin prevented gut barrier dysfunction and reduced bacterial translocation, resulting in reduced pancreatic-associated infections and decreased early mortality rates.

Effect of Bifidobacterium triple viable capsule on intestinal mucosal barrier function in rats with fatty liver induced by a high-fat diet

AIM: To investigate the potential preventive effect of Bifidobacterium triple viable capsule (Bifico) on intestinal microflora and the expression of IL-17 and occludin proteins in ileum mucosa in rats with non-alcoholic fatty liver disease NAFLD induced by a high-fat diet.

METHODS: Thirty-four male Sprague-Dawley rats were divided into three groups and were given a high-fat diet (group Ⅰ, n = 12), a high-fat diet and Bifico (group Ⅱ, n = 12), and an ordinary diet (group Ⅲ, n = 10). Rats of group Ⅱ were given Bifico gavage, while the other two groups were given the same amount of normal saline. Seventeen weeks later, the rats were killed for having a liver biopsy to confirm whether NAFLD was successfully induced. The 16S RNA method was used to detect the numbers of three main types of bacteria in the intestinal tract. The ultrastructure of ileum tissue was observed by electron microscopy, and the expression of occludin and IL-17 proteins was detected by immunohistochemistry.

RESULTS: Compared to group Ⅲ, there was a significant increase in the number of Escherichia coli, Lactobacillus, and Bifidobacteria, and expression of occludin in groups Ⅰ and Ⅱ (all P < 0.05). There was no significant difference in the number of Lactobacillus and expression of occludin between groups Ⅰ and Ⅱ. The expression of IL-17 differed significantly between the three groups (all P < 0.05). Electron microscopy indicated that intestinal epithelial cells in rats given a high-fat diet showed a series of pathological injuries (e.g., hydropsia and necrosis), and the use of Bifico could relieve intestinal epithelial injury.

CONCLUSION: Bifico exerts a preventive effect on non-alcoholic fatty liver disease induced by a high-fat in rats possibly by protecting the intestinal mucosal barrier.

Role of nutrition and microbiota in susceptibility to inflammatory bowel diseases

Inflammatory bowel diseases (IBDs), Crohn's disease (CD), and ulcerative colitis (UC) are chronic inflammatory conditions, which are increasing in incidence, prevalence, and severity, in many countries. While there is genetic susceptibility to IBD, the probability of disease development is modified by diet, lifestyle, and endogenous factors, including the gut microbiota. For example, high intakes of mono- and disaccharides, and total fats consistently increases the risk developing both forms of IBD. High vegetable intake reduces the risk of UC, whereas increased fruit and/or dietary fiber intake appears protective against CD. Low levels of certain micronutrients, especially vitamin D, may increase the risk of both diseases. Dietary patterns may be even more important to disease susceptibility than the levels of individual foods or nutrients. Various dietary regimes may modify disease symptoms, in part through their actions on the host microbiota. Both probiotics and prebiotics may modulate the microflora, and reduce the likelihood of IBD regression. However, other dietary factors affect the microbiota in different ways. Distinguishing cause from effect, and characterizing the relative roles of human and microbial genes, diet, age of onset, gender, life style, smoking history, ethnic background, environmental exposures, and medications, will require innovative and internationally integrated approaches.

Relationship between occludin expression in intestinal epithelial cells and tumor necrosis factor-α level in rats with nonalcoholic fatty liver disease

AIM: To investigate the expression of tight junction protein occludin in intestinal epithelial cells and to analyze its relationship with tumor necrosis factor-α (TNF-α) level in rats with nonalcoholic fatty liver disease (NAFLD).

METHODS: Thirty male Sprague-Dawley rats were divided into two groups: control group and model group. The control group was fed a normal diet while the model group was fed a high-fat diet. All the animals were sacrificed after 12 wk of feeding. Hematoxylin & eosin staining of hepatic tissue was performed to confirm if NAFLD was induced successfully. Serum TNF-α level was determined by radioimmunoassay. The expression of TNF-α in hepatic cells and occludin in intestinal epithelial cells was detected by immunohistochemistry. Intestinal epithelial tight junctions were observed by electron microscopy.

RESULTS: Serum TNF-α level in the model group was significantly higher than that in the control group (3.21 µg/L ± 0.45 µg/Lvs 2.10 µg/L ± 0.29 µg/L, t = -6.157, P < 0.01). In the model group, TNF-α was mainly distributed in the cytoplasm of liver cells, presenting with brownish-yellow fine granules, whereas only scattered positive cells were seen in the control group. Immunohistochemistry analysis showed that occludin was localized to the apical region of the intestinal lateral plasma membrane and distributed in a continuous pattern in the control group but significantly down-regulated and distributed in a non-continuous pattern in the model group. Electron microscopy analysis demonstrated that tight junctions were significantly shorter in the model group than in the control group (0.50 µm ± 0.21 µm vs 0.78 µm ± 0.19 µm, P < 0.05).

CONCLUSION: TNF-α may inhibit the expression of tight junction protein occludin in intestinal epithelial cells, which may result in intestinal barrier dysfunction and promote the development and progression of NAFLD.

Influence of Salvia miltiorrhizae on the mesenteric lymph node of rats with severe acute pancreatitis or obstructive jaundice

Objective. To observe the effect of salvia miltiorrhizae injection on inflammatory mediator levels and mesenteric lymph nodes in severe acute pancreatitis (SAP) and obstructive jaundice (OJ) rats and explore the protective mechanism of salvia miltiorrhizae on the lymph nodes of these rats. Methods. A total of 288 rats were used in SAP-associated and OJ-associated experiments. The rats were randomly divided into sham-operated group, model control group, and treated group. At various time points after operation, the pathological changes in mesenteric lymph nodes of rats in each group were observed, respectively. Results. The pathological severity scores in lymph nodes of SAP rats in treated group were significantly lower than those in model control group (P < .05) while the pathological changes in lymph nodes of OJ rats in treated group also showed varying degrees of mitigation. Conclusion. Salvia miltiorrhizae can exert protective effects on the lymph nodes of SAP or OJ rats via a mechanism that is associated with reducing the contents of inflammatory mediators in blood.

Serologic investigations in children with inflammatory bowel disease and food allergy

The aim of the study was the evaluation of frequency and titre of IgA ASCA and IgG ASCA and p-ANCA, c-ANCA in children with IBD and occurrence of ASCA antibodies in relation to coexistence of FA. Patients and methods. The study comprised 95 children at the ages of 2 to 18 years. The diagnosis of IBD was established on the basis of Porto criteria. Tests of blood serum were performed in all children: IgA and IgG ASCA, p-ANCA, c-ANCA using ELISA method. Results. IgE-dependent FA was found in 32.5% children with UC and in 21% with CD. We did not observe any relation between the occurrence of FA and the frequency and ASCA titre. p-ANCA were significantly more frequent in the group of children with UC. The occurrence of ASCA antibodies was observed in 73.7% of children with CD, 17.5% with UC and almost 30% with allergic colitis. Conclusions. Patients with CD and the presence of ASCA revealed a significantly more frequent localization of lesions within the small bowel and a tendency towards older age. We observed a connection between the occurrence of antibodies and the examined mutations of gene NOD2/CARD15.

Study of the protective effects of dexamethasone on ileum mucosa injury in rats with severe acute pancreatitis

OBJECTIVES

To study the protecting effects of dexamethasone on ileum mucosa injury of rats with severe acute pancreatitis (SAP).

METHODS

The SAP rats were prepared by improved Aho's methods. The plasma endotoxin and inflammatory mediators in serum were determined. The rat mortality, pathological changes of terminal ileum, nuclear factor kappa B (NF-kappaB), apoptotic indexes, and apoptotic related protein expression were observed.

RESULTS

The plasma endotoxin, inflammatory mediators, and NF-kappaB protein expression as well as pathological scores of the treatment group of ileum mucosa were lower than those of the model group at different time points. P selectin in model group significantly exceeded the dexamethasone treatment group at 3 and 6 hours (P < 0.01, P < 0.05). Caspase-3 protein expression in dexamethasone treatment group significantly exceeded the model group at 3 and 6 hours (P < 0.05), and apoptotic indexes were higher than those of the model group at 6 hours (P < 0.05), but Bax protein has shown no marked difference among groups.

CONCLUSIONS

Dexamethasone can reduce the endotoxin level and inflammatory mediators and down-regulate NF-kappaB protein expression of ileum mucosa, and ileum mucosa epithelial cell apoptosis induction was involved as well. The tissue microarrays technique is of advantage in SAP study.

Influence of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis

AIM: To study the influence and mechanisms of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis (SAP).

METHODS: The SAP rats were assigned to model, treated or sham-operated groups. The mortality, pathological changes of mesenteric lymph nodes, expression levels of NF-κB, P-selectin, Bax, Bcl-2 and caspase-3 protein and changes in apoptotic indexes in lymph nodes were observed at 3, 6 and 12 h after operation. The blood levels of endotoxin, superoxide dismutase (SOD), malondialdehyde (MDA), and endothelin-1 (ET-1) in blood were determined.

RESULTS: SOD content, expression of Bax protein and apoptotic index were significantly higher in the treated group than in the model group at different time points (P < 0.05 or P < 0.01). Other blood-detecting indexes and histopathological scores of mesenteric lymph nodes were lower in the treated than in the model group (P < 0.05, P < 0.01 or P < 0.01). NF-κB protein expression was negative in all groups. Comparing P-selectin and caspase-3 expression levels among all three groups, there was no marked difference between the model and treated group.

CONCLUSION: Dexamethasone can protect mesenteric lymph nodes. The mechanism may be by reducing the content of inflammatory mediators in the blood and inducing lymphocyte apoptosis.

Mechanism of acute pancreatitis complicated with injury of intestinal mucosa barrier

Acute pancreatitis (AP) is a common acute abdomen in clinic with a rapid onset and dangerous pathogenetic condition. AP can cause an injury of intestinal mucosa barrier, leading to translocation of bacteria or endotoxin through multiple routes, bacterial translocation (BT), gut-origin endotoxaemia, and secondary infection of pancreatic tissue, and then cause systemic inflammatory response syndrome (SIRS) or multiple organ dysfunction syndrome (MODS), which are important factors influencing AP's severity and mortality. Meanwhile, the injury of intestinal mucosa barrier plays a key role in AP's process. Therefore, it is clinically important to study the relationship between the injury of intestinal mucosa barrier and AP. In addition, many factors such as microcirculation disturbance, ischemic reperfusion injury, excessive release of inflammatory mediators and apoptosis may also play important roles in the damage of intestinal mucosa barrier. In this review, we summarize studies on mechanisms of AP.

The secretory immunoglobulin A response to Mycobacterium tuberculosis in a childhood population

We report on the measurement of saliva anti-Purified Protein Derivative sIgA and 38kDa antibodies from 127 children, of whom 31 were strong tuberculosis suspects and 96 were healthy contact children. The results concerning the percentage of children with antibody reactivity to PPD and 38kDa antigens showed that, of these 2 antigens, 38kDa induced higher reactivity in patients positive and negative for the Tuberculin Skin Test (28% and 16.6%, respectively) in comparison to controls positive and negative for the TST (11.7% and 7.1%, respectively). There was a statistically significant difference between patients positive and controls negative for the TST. In relation to the Purified Protein Derivative antigen, while 14.2% of patients positive for the TST showed antibody reactivity to the PPD antigen, no patients negative for the TST had reactivity to this antigen. The findings suggest that these two antigens seem be associated with a different development of the mucosal defence mechanisms mediated by sIgA against Mycobacterium tuberculosis.

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Eustachian tube possesses immunological characteristics as a mucosal effector site and responds to P6 outer membrane protein of nontypeable Haemophilus influenzae

The eustachian tube (ET) plays an important role in the pathogenesis of otitis media (OM). To better understand its biology and to develop a nasal vaccine for preventing OM, mucosal lymphocytes in the ET were analyzed, and the ET's immunological function was investigated. Mononuclear cells were isolated from murine ET, and lymphocyte subsets were analyzed by flow cytometry. Antibody-producing cells were determined by enzyme-linked immunospot assay. The expression of cytokine mRNA in ET CD4(+) T cells was determined by RT-PCR. Results in naive mice showed that the ET contained many immunocompetent cells, including a relative large number of IgA-producing cells and Th2 cytokine-expressing T cells. Next, we investigated antigen-specific immune responses in the ET. Mice were immunized intranasally with the P6 outer membrane of nontypeable Haemophilus influenzae (NTHi) and cholera toxin (CT), and P6-specific immune responses in the ET were examined. P6-specific IgA producing cells markedly increased in the ET. Moreover, in vitro stimulation with P6 of purified CD4(+) T cells from immunized mice resulted in the proliferation of CD4(+) T cells that expressed Th2 cytokine mRNA. These results indicate that the ET might be characterized as a mucosal effector site and that antigen-specific IgA and Th2 immune responses could be induced in the ET by intranasal immunization. These findings suggest that the ET might be a key immunological organ in the pathogenesis of OM, and in the development of a nasal vaccine.

Tumor necrosis factor-alpha induces apoptosis of enterocytes in mice with fulminant hepatic failure

AIM: To explore the alterations of intestinal mucosa morphology, and the effects of tumor necrosis factor α (TNFα) on enterocyte apoptosis in mice with fulminant hepatic failure (FHF).

METHODS: Liver damage was induced by lipopolysaccharide (LPS)/TNF-α in D-galactosamine (GalN) sensitized BALB/c mice. There were 40 mice in normal saline (NS)-treated group, 40 mice in LPS-treated group, 40 mice in GalN-treated group, 120 mice in GalN/ LPS-treated group and 120 mice in GalN/ TNFα-treated group. Each group was divided into five subgroups of eight mice each. Serum samples and liver, intestinal tissues were respectively obtained at 2, 6, 9, 12 and 24 h after administration. Anti-TNFα monoclonal antibody was injected intravenously into GalN/LPS-treated mice. Serum TNFα levels were determined by enzyme-linked immunosorbent assays (ELISA). Serum ALT levels were determined using an automatic analyzer. The intestinal tissues were studied under light microscope and electron microscope at 2, 6, 9, 12 and 24 h in mice with fulminant hepatic failure, respectively. Enterocyte apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method. The expression of tumor necrosis factor receptor 1 (TNFR1) in intestinal tissue was tested by immunohistochemistry Envision Two Steps.

RESULTS: Gut mucosa was morphologically normal at all time points in all groups, but typical apoptotic cells could be seen in all experimental groups under electron micro-scope. Apoptosis rate of gut mucosal epithelial cells were significantly increased at 6, 9 and 12 h, peaked at 12 h in mice with fulminant hepatic failure. TNFα induced apoptosis of enterocytes in mice with FHF. The integrated OD (IOD) levels of TNFα receptor 1 protein expressed in the intestine of mice with GalN/LPS and GalN/ TNFα-induced FHF at 2, 6, 9, 12 and 24 h after GalN/LPS and GalN/TNFα administration were 169.54±52.62/905.79±111.84, 11350.67±2133.26/28160.37±4601.67, 25781.00±2277.75/122352.30±49412.40, 5241.53±3007.24/49157.93±9804.88, 7086.13±1031.15/3283.45±127.67, respectively, compared with those in control groups (with NS, LPS and GalN administration, respectively). IOD level of TNFR1 changed significantly at 6, 9 and 12 h after GalN/LPS and GalN/TNFα administration. The expression of TNFR1 protein was significantly higher at 9 h after GalN/LPS and GalN/TNFα administration than that in control groups. Protein expression of TNFR1 was positively correlated with enterocyte apoptosis.

CONCLUSION: TNFα can induce apoptosis of enterocytes in mice with FHF. Anti-TNFα IgG can inhibit this role.

Effect of TNF-α on tight junctions between the epithelial cells of intestinal mucosal barrier

AIM: To investigate the effect of TNF-α on tight junctions between the epithelial cells of the intestinal mucosal barrier.

METHODS: Colon cancer cell line (CaCo-2) was cultured. The localizations of zonula occluden-1 (ZO-1) in CaCo-2 epithelial cells were detected by immunofluorescence after exposure to TNF-α (0, 50, 100 and 200 mg/L) for 24 h and the TNF-α treatment with 100 mg/L for 0, 4, 8 and 24 h. The expression level of ZO-1 was analyzed by semi-quantitative reverse transcriptase-PCR after exposure to TNF-α with the above time and concentration.

RESULTS: Different expression levels of ZO-1 depended on different time and concentration of TNF-α treated on CaCo-2 epithelial cells. The integrity of tight junctions was disrupted and the expression level of ZO-1 decreased after treatment with TNF-α. The intensity of the immunofluorescent signal was less intensive after exposure to TNF-α 100 and 200 mg/L than that to 0 and 50 mg/L. The intensity of the immunofluorescent signal was less intensive after exposure to TNF-α 100 mg/L for 24 hours than those for 0 h, 4 h and 8 h. The RT-PCR results showed that after CaCo-2 cells were treated for 24h with the indicated concentrations (0, 50, 100 and 200 mg/L) of TNF-α and the TNF-α treatment with 100 mg/L for 0 h, 4 h, 8 h and 24 h, the expression levels of ZO-1 mRNA in CaCo-2 cells were decreased by TNF-α with 100 mg/L for 24 h, as compared with control (P < 0.01).

CONCLUSION: Tight junctions between the epithelial cells of the intestinal mucosal barrier can be destroyed by TNF-α, and decreased expression level of ZO-1 induced by TNF-α is one of the most important molecular mechanisms.

Therapeutic effects of a new lymphocyte homing reagent FTY720 in interleukin-10 gene-deficient mice with colitis

BACKGROUND

FTY720 is a novel reagent that possesses potent immunosuppressive activity. The immunosuppression induced by FTY720 is mediated by completely different mechanisms from those of conventional immunosuppressants, that is, by altering the tissue distribution of lymphocytes rather than inhibiting activation. In this study, we examined the efficacy of FTY720 in the treatment of chronic colitis in an interleukin-10 gene-deficient (IL-0-/-) mouse model.

METHODS

FTY720 was administered orally for 4 weeks to IL-10-/- mice with clinical signs of colitis. The gross and histologic appearance of the colon and the numbers, phenotype, cytokine production, and apoptosis of lymphocytes were compared with those characteristics in a control group.

RESULTS

Single-dose administration of FTY720 resulted in the sequestration of circulating lymphocytes within the secondary lymphoid tissues. Four-week administration resulted in a significant reduction of the CD4+ T lymphocytes subpopulation in the colonic lamina propria and IFN-gamma production of the colonic lymphocytes, accompanied by a significant decrease in the severity of colitis.

CONCLUSIONS

Treatment of established colitis in IL-10-/- mice with FTY720 ameliorated the colitis, probably as a result of decreasing the number of lymphocytes in the colonic mucosa and an associated reduction in IFN-gamma production.

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Increased serum nIgM in voluntarily physically active rats: a potential role for B-1 cells

Moderate, habitual physical activity improves health, possibly because of beneficial changes in immune function. For example, physical activity can increase natural killer cell cytotoxicity, T cell proliferation, and macrophage function but has minimal impact on antigen-driven B-2-mediated immunoglobulin (Ig) responses. The following studies tested whether physical activity selectively impacts nonantigen-driven B-1-natural IgM (nIgM) but not antigen-driven B-2 Ig. Adult male, pathogen-free Sprague-Dawley rats in a barrier facility voluntarily ran in wheels from 7 to 56 days or were housed in an enriched environment for 56 days. Rats received either no antigen or keyhole limpet hemocyanin (KLH) to assess the B-2 response. Blood samples assessed serum nIgM, total IgG, total serum protein, anti-KLH IgM, and anti-KLH IgG. Physically active rats had higher serum nIgM after 7 days of running, and nIgM remained elevated over 56 days of running. In contrast, free-wheel running produced no changes in total IgG, total serum protein, anti-KLH IgM, and anti-KLH IgG. Environmental enrichment did not alter immune measures from controls. These results suggest that B-1, not B-2, cell responses are selectively impacted by physical activity. Because nIgM is important in multiple aspects of the immune response, an elevation in this innate humoral component could contribute to improved immunity in physically active organisms.