Increased activation of isolated intestinal lamina propria mononuclear cells in inflammatory bowel disease

CD4 T-Cell Subsets and the Pathophysiology of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an umbrella term for the chronic immune-mediated idiopathic inflammation of the gastrointestinal tract, manifesting as Crohn's disease (CD) or ulcerative colitis (UC). IBD is characterized by exacerbated innate and adaptive immunity in the gut in association with microbiota dysbiosis and the disruption of the intestinal barrier, resulting in increased bacterial exposure. In response to signals from microorganisms and damaged tissue, innate immune cells produce inflammatory cytokines and factors that stimulate T and B cells of the adaptive immune system, and a prominent characteristic of IBD patients is the accumulation of inflammatory T-cells and their proinflammatory-associated cytokines in intestinal tissue. Upon antigen recognition and activation, CD4 T-cells differentiate towards a range of distinct phenotypes: T helper(h)1, Th2, Th9, Th17, Th22, T follicular helper (Tfh), and several types of T-regulatory cells (Treg). T-cells are generated according to and adapt to microenvironmental conditions and participate in a complex network of interactions among other immune cells that modulate the further progression of IBD. This review examines the role of the CD4 T-cells most relevant to IBD, highlighting how these cells adapt to the environment and interact with other cell populations to promote or inhibit the development of IBD.

Host-microbiota interaction-mediated resistance to inflammatory bowel disease in pigs

BACKGROUND

Disease resistance phenotypes are associated with immune regulatory functions and immune tolerance and have implications for both the livestock industry and human health. Microbiota plays an essential role in regulating immunity and autoimmunity in the host organism, but the influence of host-microbiota interactions on disease resistance phenotypes remains unclear. Here, multiomics analysis was performed to identify potential regulatory mechanisms of disease resistance at both the microbiome and host levels in two pig breeds.

RESULTS

Acute colitis models were established in Min pigs and Yorkshire pigs, and control and diseased individuals were compared. Compared with Yorkshire pigs under the same nutritional and management conditions, Min pigs exhibited strong disease resistance, as indicated by a low disease activity index (DAI) and a low histological activity index (HAI). Microbiota sequencing analysis showed that potentially harmful microbes Desulfovibrio, Bacteroides and Streptococcus were enriched in diseased individuals of the two breeds. Notably, potentially beneficial microbes, such as Lactobacillus, Clostridia and Eubacterium, and several genera belonging to Ruminococcaceae and Christensenellaceae were enriched in diseased Min pigs and were found to be positively associated with the microbial metabolites related to intestinal barrier function. Specifically, the concentrations of indole derivatives and short-chain fatty acids were increased in diseased Min pigs, suggesting beneficial action in protecting intestinal barrier. In addition, lower concentrations of bile acid metabolites and short-chain fatty acids were observed in diseased Yorkshire pigs, which were associated with increased potentially harmful microbes, such as Bilophila and Alistipes. Concerning enrichment of the immune response, the increase in CD4⁺ T cells in the lamina propria improved supervision of the host immunity response in diseased Min pigs, contributing to the maintenance of Th2-type immune superiority and immune tolerance patterns and control of excessive inflammation with the help of potentially beneficial microbes. In diseased Yorkshire pigs, more terms belonging to biological processes of immunity were enriched, including Toll-like receptors signalling, NF-κB signalling and Th1 and Th17-type immune responses, along with the increases of potentially harmful microbes and damaged intestinal barrier.

CONCLUSIONS

Cumulatively, the results for the two pig breeds highlight that host-microbiota crosstalk promotes a disease resistance phenotype in three ways: by maintaining partial PRR nonactivation, maintaining Th2-type immune superiority and immunological tolerance patterns and recovering gut barrier function to protect against colonic diseases. Video abstract.

Upregulation of signal transducer and activator of transcription 3 in dogs with chronic inflammatory enteropathies

Background

In inflammatory bowel disease (IBD) in humans, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is upregulated in mucosal epithelial cells and correlates with clinical severity.

Hypothesis/Objective

To investigate the expression pattern of pSTAT3 in the mucosa of dogs with chronic inflammatory enteropathy (CIE) and explore correlations between its expression and clinical and histopathological severity scoring.

Animals

Twenty‐eight canine CIE patients grouped into food‐responsive enteropathy (FRE;  9), steroid‐responsive enteropathy (SRE;  10), and protein‐losing enteropathy (PLE;  9). Ten healthy beagle dogs served as controls (CO).

Methods

Retrospective case control study. Immunohistochemistry was used to detect pSTAT3 in canine duodenal mucosa samples.

Results

Compared to CO, SRE (P < .001) and PLE (P < .001) dogs had significantly higher pSTAT3 expression in the villus epithelium. The SRE group had a significantly higher expression in the villus lamina propria (VLP) compared to controls (P = .009). In the crypt epithelium (CE), all CIE dogs had significantly higher pSTAT3 expression (FRE, P = .002; SRE, P = .003; PLE, P < .001) compared to CO. In the lamina propria crypt region (CLP), dogs with FRE (P = .04) and SRE (P = .03) had significantly upregulated pSTAT3 compared to controls. A positive correlation was found between canine chronic enteropathy clinical activity index (CCECAI) scoring and pSTAT3 expression for both epithelial (rho = .541; P < .001) and crypt regions (rho = .32; P = .02).

Conclusions and Clinical Importance

pSTAT3 is upregulated in CIE in dogs, correlates with clinical severity, and may be helpful as a clinical marker in dogs with CIE.

Gut microbiota modulation and anti-inflammatory properties of mixed lactobacilli in dextran sodium sulfate-induced colitis in mice

Correlations between gut microbiota activities and inflammatory bowel disease (IBD) treatment are gaining research interest. In our previous study, Lactobacillus acidophilus KLDS 1.0901, Lactobacillus helveticus KLDS 1.8701, and Lactobacillus plantarum KLDS 1.0318 showed antibacterial, antioxidant, and immunomodulatory activities. In the current study, we evaluated the effects of three tested strains and their mixture on dextran sulfate sodium (DSS)-induced colitis in C57BL/6J mice. The three tested strains and their mixture significantly decreased the disease activity index (DAI), colon shortening, and myeloperoxidase (MPO) activity. Additionally, the three tested strains and their mixture improved the histological damage, increased the colonic mucous layer integrity, and exhibited lower levels of prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), while up-regulating colonic anti-inflammatory cytokine IL-10 levels, tight junction proteins (E-cadherin, zonulae occludens (ZO)-1, occludin and claudin-1) and mucin (MUC1 and MUC2) mRNA expressions to some extent. In addition, mixed lactobacilli showed better anti-inflammatory effects than single-strain treatment. Our study further revealed that mixed lactobacilli increased bacterial diversity and improved gut microbiota composition, increasing short-chain fatty acid (SCFA) production. These results indicated that mixed lactobacilli supplementation could attenuate DSS-induced colitis by modulating the gut microbiota and repairing the intestinal barrier, which provided a scientific basis for its clinical application in the future.

Could Ergothioneine Aid in the Treatment of Coronavirus Patients?

Infection with SARS-CoV-2 causes the coronavirus infectious disease 2019 (COVID-19), a pandemic that has, at present, infected more than 11 million people globally. Some COVID-19 patients develop a severe and critical illness, spurred on by excessive inflammation that can lead to respiratory or multiorgan failure. Numerous studies have established the unique array of cytoprotective properties of the dietary amino acid ergothioneine. Based on studies in a range of in vitro and in vivo models, ergothioneine has exhibited the ability to modulate inflammation, scavenge free radicals, protect against acute respiratory distress syndrome, prevent endothelial dysfunction, protect against ischemia and reperfusion injury, protect against neuronal damage, counteract iron dysregulation, hinder lung and liver fibrosis, and mitigate damage to the lungs, kidneys, liver, gastrointestinal tract, and testis, amongst many others. When compiled, this evidence suggests that ergothioneine has a potential application in the treatment of the underlying pathology of COVID-19. We propose that ergothioneine could be used as a therapeutic to reduce the severity and mortality of COVID-19, especially in the elderly and those with underlying health conditions. This review presents evidence to support that proposal.

Targeting T cells in inflammatory bowel disease

T cells play a pivotal role in the immune response underlying inflammatory bowel disease (IBD) pathogenesis. On this basis, over the past 25 years several drugs have assessed to target T cells in IBD patients. Amongst anti-CD3 antibodies, visilizumab and foralumab did not show clinical efficacy in ulcerative colitis (UC) and Crohn's disease (CD) patients, respectively, whereas otelixizumab has been tested in vitro only. The anti-CD4 BF-5 and cM-T412, and the anti-CD25 basiliximab and daclizumab were not effective in CD and UC patients, respectively. The anti-NKG2D antibody NNC0142-0002 showed clinical benefit in CD patients, in particular in biologic naïve ones, in a randomized, double-blind, parallel-group, placebo-controlled trial. The anti-CD40L M90 and the GSK1349571A blocking calcium release-activated calcium (CRAC) channels, which are involved in the T cell activation and proliferation, were tested only in ex vivo/in vitro experiments. Apart from ustekinumab, all the other drugs targeting T cell-derived cytokines failed. The reinduction of lamina propria T cell apoptosis is a mechanism to modulate T cell survival exploited by cyclosporin A, azathioprine and anti-tumor necrosis factor-α agents, such as infliximab, adalimumab and golimumab. In this article, we review the drugs targeting T cells via surface receptors, via T cell-derived cytokines, via CRAC channels or by inducing apoptosis.

Natural Product-Based Nanomedicine in Treatment of Inflammatory Bowel Disease

: Many synthetic drugs and monoclonal antibodies are currently in use to treat Inflammatory Bowel Disease (IBD). However, they all are implicated in causing severe side effects and long-term use results in many complications. Numerous in vitro and in vivo experiments demonstrate that phytochemicals and natural macromolecules from plants and animals reduce IBD-related complications with encouraging results. Additionally, many of them modify enzymatic activity, alleviate oxidative stress, and downregulate pro-inflammatory transcriptional factors and cytokine secretion. Translational significance of natural nanomedicine and strategies to investigate future natural product-based nanomedicine is discussed. Our focus in this review is to summarize the use of phytochemicals and macromolecules encapsulated in nanoparticles for the treatment of IBD and IBD-associated colorectal cancer.

Total CD3 T Cells Are Necessary and Sufficient to Induce Colitis in Immunodeficient Mice With Dendritic Cell-Specific Deletion of TGFbR2: A Novel IBD Model to Study CD4 and CD8 T-Cell Interaction

BACKGROUND

Inflammatory bowel disease (IBD) is a multifactorial disorder, with the innate and adaptive immune cells contributing to disease initiation and progression. However, the intricate cross-talk between immune cell lineages remains incompletely understood. The role of CD8+ T cells in IBD pathogenesis has been understudied, largely due to the lack of appropriate models.

METHODS

We previously reported spontaneous colitis in mice with impaired TGFβ signaling due to dendritic cell-specific knockout of TGFbR2 (TGFβR2ΔDC). Here, we demonstrate that crossing TGFβR2ΔDC mice with a Rag1-/- background eliminates all symptoms of colitis and that adoptive transfer of unfractionated CD3+ splenocytes is sufficient to induce progressive colitis in Rag1-/-TGFβR2ΔDC mice.

RESULTS

Both CD4+ and CD8+ T cells are required for the induction of colitis accompanied by activation of both T-cell lineages and DCs, increased expression of mucosal IFNγ, TNFα, IL6, IL1β, and IL12, and decreased frequencies of CD4+FoxP3+ regulatory T cells. Development of colitis required CD40L expression in CD4+ T cells, and the disease was partially ameliorated by IFNγ neutralization.

CONCLUSIONS

This novel model provides an important tool for studying IBD pathogenesis, in particular the complex interactions among innate and adaptive immune cells in a controlled fashion, and represents a valuable tool for preclinical evaluation of novel therapeutics.

Crohn's Disease Patients in Remission Display an Enhanced Intestinal IgM⁺ B Cell Count in Concert with a Strong Activation of the Intestinal Complement System

Inflammatory bowel disease (IBD) is an umbrella term that comprises Crohn's disease (CD) and ulcerative colitis (UC). Both entities are characterized by a disturbed mucosal immune response and an imbalance of intestinal microbiota composition. The complement system (C) plays a critical role in the detection, and clearance of bacteria and dysregulation of single complement components has been linked to IBD. Here, we asked if the C contributes to distinct subtypes of inflammation observed in CD and UC. We performed systematical expression analyses of the intestinal C in IBD patients and controls. Immunohistochemistry or immunoblot experiments were performed to verify qPCR data. Activity of the three activation pathways of C was studied in sera samples. In CD patients a strong upregulation of the C was observed enabling the definition of unique expression patterns being associated either with remission or active disease. These data were reflected by an enhanced C activation in sera and fecal samples. An excessive mucosal presence of immunoglobulin M (IgM) and CR2/CD21 positive B cells in concert with decreased fecal IgA level was identified in CD patients in remission. These findings point to an exacerbated induction of the intestinal C that may potentially be involved in the etiology of CD.

Overexpression of CD98 in intestinal epithelium dysregulates miRNAs and their targeted proteins along the ileal villus-crypt axis

CD98 has been implicated in the experimental model of inflammatory bowel disease. We have previously shown that IEC-specific overexpression of CD98 mediates intestinal inflammation and intestinal epithelial barrier dysfunction. Mice overexpressing CD98 exhibited severe colitis and a greater susceptibility to CAC. Here we demonstrated CD98 overexpression to dysregulate homeostatic gradient profile of miRNA and protein expression along the ileal villus-crypt axis. Using miRNA-target gene prediction module, we observed differentially expressed miRNAs to target proteins of villus and crypt profoundly affected by CD98 overexpression. We have utilized online bioinformatics as methods to further scrutinize the biological meanings of miRNA-target data. We identified significant interactions among the differentially regulated proteins targeted by altered miRNAs in Tg mice. The biological processes affected by the predicted targets of miRNAs deviate from the homeostatic functions of the miRNA-gene-protein axis of the wildtype mice. Our results emphasize a dynamic perturbation of miRNA and protein expression in villus-crypt axis contributing to potential biological consequences of altering CD98 expression. Our findings also suggest the need for a consideration of arrays of interacting biological entities (i.e. miRNAs-mRNAs, protein-protein interaction) or a combination comparison for a better understanding of the disease pathology which is necessary for an effective therapeutic target development.

Immune Responses to Intestinal Microbes in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are characterized by chronic, T-cell-mediated inflammation of the gastrointestinal tract that can cause significant, lifelong morbidity. Data from both human and animal studies indicate that IBDs are likely caused by dysregulated immune responses to resident intestinal microbes. Certain products from mycobacteria, fungi, and Clostridia stimulate increased effector T cell responses during intestinal inflammation, whereas other bacterial products from Clostridia and Bacteroides promote anti-inflammatory regulatory T cell responses. Antibody responses to bacterial and fungal components may help predict the severity of IBDs. While most currently approved treatments for IBDs generally suppress the patient's immune system, our growing understanding of microbial influences in IBDs will likely lead to the development of new diagnostic tools and therapies that target the intestinal microbiota.

Nanoparticles with surface antibody against CD98 and carrying CD98 small interfering RNA reduce colitis in mice

BACKGROUND & AIMS

Nanoparticles have been explored as carriers of small interfering RNAs (siRNAs) and might be developed to treat patients with inflammatory bowel disease (IBD). Overexpression of CD98 on the surface of colonic epithelial cells and macrophages promotes the development and progression of IBD. We developed an orally delivered hydrogel that releases nanoparticles with single-chain CD98 antibodies on their surface (scCD98 functionalized) and loaded with CD98 siRNA (siCD98). We tested the ability of the nanoparticles to reduce levels of CD98 in the colons of mice with colitis.

METHODS

scCD98-functionalized siCD98-loaded nanoparticles were fabricated using a complex coacervation technique. We investigated the cellular uptake and lysosome escape profiles of the nanoparticles in Colon-26 cells and RAW 264.7 macrophages using fluorescence microscopy. Colitis was induced by transfer of CD4(+)CD45RB(high) T cells to Rag(-/-) mice or administration of dextran sodium sulfate to C57BL/6 mice. Mice were then given hydrogel (chitosan and alginate) containing scCD98-functionalized nanoparticles loaded with siCD98 or scrambled siRNA (control) via gavage.

RESULTS

The scCD98-functionalized nanoparticles were approximately 200 nm in size and had high affinity for CD98-overexpressing cells. The scCD98-functionalized siCD98-loaded nanoparticles significantly reduced levels of CD98 in Colon-26 cells and RAW 264.7 macrophages, along with production of inflammatory cytokines (tumor necrosis factor α, interleukin-6, and interleukin-12). In mice with colitis, administration of the scCD98-functionalized siCD98-loaded nanoparticles reduced colon expression of CD98. Importantly, the severity of colitis was also reduced compared with controls (based on loss of body weight, myeloperoxidase activity, inflammatory cytokine production, and histological analysis). Approximately 24.1% of colonic macrophages (CD11b(+)CD11c(-)F4/80(+)) in the mice had taken up fluorescently labeled siRNA-loaded nanoparticles within 12 hours of administration.

CONCLUSIONS

Nanoparticles containing surface CD98 antibody and loaded with siCD98 reduce expression of this protein by colonic epithelial cells and macrophages, and oral administration decreases the severity of colitis in mice. This nanoparticle in hydrogel (chitosan/alginate) formulation might be developed to treat patients with IBD.

Glycoprotein CD98 as a receptor for colitis-targeted delivery of nanoparticle

Treatment strategies for inflammatory bowel disease have been constrained by limited therapeutic efficacy and serious adverse effects owing to a lack of receptor for targeted drug delivery to the inflamed colon. Upon inflammation, CD98 expression is highly elevated in colonic epithelial cells and infiltrating immune cells. To investigate whether CD98 can be used as a colitis-targeted delivery receptor, we constructed CD98 Fab'-bearing quantum dots (QDs)-loaded nanoparticles (Fab'-NPs). The resultant Fab'-NPs had desired particle size (~458 nm) with a narrow size distribution and zeta-potential (approximately +19 mV), low cytotoxicity, and excellent fluorescence properties. Electron microscopy images provided direct evidence for the well-dispersed distribution of QDs within spherical Fab'-NPs. Cellular uptake experiments demonstrated that Fab'-NPs were efficiently internalized into Colon-26 and RAW 264.7 cells through the CD98-mediated endocytosis pathway, and showed that the targeting effect of CD98 Fab' markedly increased their cellular uptake efficiency compared with control pegylated QDs-loaded NPs (PEG-NPs). Furthermore, ex vivo studies showed much more effective accumulation of Fab'-NPs in colitis tissue than that of PEG-NPs. These findings suggest that because of inflammation-dependent over-expression of CD98, active colitis-targeted delivery can be accomplished using NPs decorated with CD98 antibody.

Bcl-2/caspase 3 mucosal imbalance favors T cell resistance to apoptosis in dogs with inflammatory bowel disease

Canine idiopathic inflammatory bowel disease (IBD) is believed to result from complex interplay between genetic, microbial, and immunologic factors. Abnormal cell death by apoptosis may result in the persistence of activated intestinal T cells that contribute to mucosal inflammation and clinical severity. To test this hypothesis, we investigated the mucosal expression of pro- and anti-apoptotic proteins in different intestinal compartments and their association with inflammatory indices in dogs with IBD. Apoptosis of lamina propria (LP) T cells in duodenal, ileal, and colonic tissues in control and IBD dogs was analyzed by caspase 3/Bcl-2 immunohistochemistry and TUNEL assays. Densities and distributions of LP caspase 3 and Bcl-2 cells were correlated to histopathologic lesions and the clinical activity index (CIBDAI). Compared to control tissues, IBD dogs had significantly (P<0.01) fewer caspase 3 cells in colonic mucosa. Double immunostaining identified the majority of apoptotic cells as TUNEL(+)/caspase 3(+). Within intestinal mucosa of IBD dogs, there were significantly greater numbers of Bcl-2 cells at the apical and basilar villus in the duodenum as compared to the colon and to the apical and basilar villus in the ileum (P<0.001 for all comparisons). There were significantly greater numbers of Bcl-2 cells at the apical and basilar villus of the duodenum but significantly fewer numbers of Bcl-2 cells at the apical villus of the ileum in IBD dogs compared with controls (P<0.001, P<0.001, and P<0.02, respectively). There was a significant association between the number of Bcl-2 cells in the duodenum of IBD dogs and the CIBDAI (P<0.001 each for mild, moderate and severe clinical IBD). In conclusion, apoptosis of T lymphocytes varies within intestinal compartments of dogs with IBD. Mucosal imbalance of Bcl-2/caspase 3 expression favors T cell resistance to apoptosis which may contribute to T cell accumulation and chronic intestinal inflammation, similar to human IBD.

Soluble interleukin-2 receptors in ulcerative colitis

T-Cell activation results in the release or shedding of a soluble form (45 kDa) of the cellular (55 kDa) low-affinity interleukin-2 receptor (α-chain) (slL-2R). The present study was performed to investigate if the serum concentration of sIL-2R is a marker of disease activity in patients with ulcerative colitis (UC), a chronic inflammatory bowel disease. Twenty-seven UC patients (about half of them in remission) and 13 healthy volunteers were studied, sIL-2R concentrations were measured by an enzyme-linked immunosorbent assay, and significantly elevated median sIL-2R values were found in clinically active UC (150 pg/ml; range 100–420), compared to inactive UC (145 pg/ml; range 110–255), and healthy controls (110 pg/ml; range 80–165) (p < 0.01). There was no correlation between sIL-2R concentrations and extent of the disease. Due to the overlap of serum sIL-2R concentrations between different disease stages and controls, the general diagnostic value seems to be limited. However, since slL-2R release is an IL-2 dependent phenomenon, we conclude that the demonstration of increased serum sIL-2R concentrations in UC suggests the existence of an enhanced T-cell activation in vivo in this disease. Further longitudinal studies are required to elucidate if repeated measurements of sIL-2R levels provide an additional way of monitoring UC disease activity in individual patients.

The role of cytokines in inflammatory bowel disease

Cytokines play an important role in the development and persistence of the inflammatory lesions seen in Crohn's disease and ulcerative colitis. This review discusses the current thinking of the role of cytokines in chronic intestinal inflammation including the involvement of immunoregulatory cytokines within the Th1 and Th2 subsets.

Mechanism of action of 5-arninosalicylic acid

5-Aminosalicylic Acid (5-ASA) has been used for over 50 years in the treatment of inflammatory bowel disease in the pro-drug form sulphasalazine (SASP). SASP is also used to treat rheumatoid arthritis. However whether the therapeutic properties of SASP are due to the intact molecule, the 5-ASA or sulphapyridine components is unknown. Several mechanisms of action have been proposed for 5-ASA and SASP including interference in the metabolism of arachidonic acid to prostaglandins and leukotrienes, scavenging,of reactive oxygen species, effects on leucocyte function and production of cytokines. However, it is unlikely that the anti-inflammatory properties of SASP and 5-ASA are due to several different properties but more likely that a single property of 5-ASA explains the theraapeutic effects of 5-ASA and SASP. Reactive oxygen species (ROS) are involved in the metabolism of prostaglandins and leukotrienes and can act as second messengers, and so the scavenging of ROS may be the single mechanism of action of 5-ASA that gives rise to its antiinflammatory effects in both inflammatory bowel disease and rheumatoid arthritis.

Homeostatic and innate immune responses: role of the transmembrane glycoprotein CD98

The transmembrane glycoprotein CD98 is a potential regulator of multiple functions, including integrin signaling and amino acid transport. Abnormal expression or function of CD98 and disruption of the interactions between CD98 and its binding partners result in defects in cell homeostasis and immune responses. Indeed, expression of CD98 has been correlated with diseases such as inflammation and tumor metastasis. Modulation of CD98 expression and/or function therefore represents a promising therapeutic strategy for the treatment and prevention of such pathologies. Herein, we review the role of CD98 with focus on its functional importance in homeostasis and immune responses, which could help to better understand the pathogenesis of CD98-associated diseases.

Expression of CD4+ forkhead box P3 (FOXP3)+ regulatory T cells in inflammatory bowel disease

OBJECTIVE

Forkhead box P3 (FOXP3) plays an important role in the development and function of CD4(+) regulatory T (Treg) cells. In this study the percentage of CD4(+) FOXP3(+) Treg cells in peripheral blood mononuclear cells (PBMC) and the frequency of Treg cells in the colonic mucosa of patients with inflammatory bowel disease (IBD) were investigated.

METHODS

The percentage of CD4(+) FOXP3(+) Treg cells in PBMC was analyzed by flow cytometry. Immunohistochemistry was used to examine the FOXP3(+) cells in the inflamed mucosa. Real-time polymerase chain reaction and Western blot were used to detect the expressions of FOXP3 mRNA and protein in PBMC and mucosal biopsy specimens of IBD patients, respectively.

RESULTS

Together with the decrease of percentage of Treg cells in PBMC, we found that the frequency of Treg cells increased significantly in inflamed mucosa of active or inactive Crohn's disease (CD) and ulcerative colitis (UC). The expressions of FOXP3 mRNA and protein increased in inflamed mucosa when compared with those in healthy controls, especially the FOXP3 mRNA in patients with active CD or UC. Interestingly, the expression of FOXP3 protein in active UC was higher than that in active CD.

CONCLUSIONS

There was a decrease of CD4(+) FOXP3(+) Treg cells in peripheral blood and an accumulation of Treg cells in inflamed mucosa. These data suggested that the suppressive function of Treg cells may be partially inhibited and this could be an important factor in the recurrence of disease, especially in UC.

p53 antibodies, metallothioneins, and oxidative stress markers in chronic ulcerative colitis with dysplasia

AIM: To investigate the role of p53 antibodies (p53Abs), metallothioneins (MTs) and oxidative stress markers in the early detection of dysplasia in chronic ulcerative colitis (UC).

METHODS: The study included 30 UC patients, 15 without dysplasia (group II) and 15 with dysplasia (group III), in addition to 15 healthy volunteers (group I, control subjects). The enzyme-linked immunosorbent assay technique was used to measure serum p53Abs and MTs, while advanced oxidation protein products (AOPPs), and reduced glutathione (GSH) levels were measured by spectrophotometric method in all subjects.

RESULTS: In group II and group III compared to group I, there were significant increases in serum levels of AOPPs (145.94 ± 29.86 μmol/L and 192.21 ± 46.71 μmol/L vs 128.95 ± 3.06 μmol/L, P < 0.002 and P < 0.001, respectively), MTs (8.18 ± 0.35 μg/mL and 9.20 ± 0.58 μg/mL vs 6.12 ± 0.25 μg/mL, P < 0.05 and P < 0.05, respectively), and p53Abs (20.19 ± 3.20 U/mL and 34.66 ± 1.34 U/mL vs 9.42 ± 1.64 U/mL, P < 0.001 and P < 0.001, respectively). There were significantly higher levels of AOPPs (P < 0.05) and p53Abs (P < 0.001) in UC patients with dysplasia compared to those without dysplasia, while MTs showed no significant difference between the 2 groups (P > 0.096). In contrast, GSH levels showed a significant decrease in both patients’ groups (1.87 ± 0.02 μmol/mL and 1.37 ± 0.09 μmol/mL vs 2.49 ± 0.10 μmol/mL, P < 0.05 and P < 0.05 in groups II and III, respectively) compared with group I, and the levels were significantly lower in group III than group II (P < 0.05). There was a positive correlation between AOPPs and both MTs (r = 0.678, P < 0.001) and p53Abs (r = 0.547, P < 0.001), and also between p53Abs and MTs (r = 0.739, P < 0.001). There was a negative correlation between AOPPs and GSH (r = -0.385, P < 0.001), and also between GSH and both MTs (r = -0.662, P < 0.001) and p53Abs (r = -0.923, P < 0.001).

CONCLUSION: Oxidative stress and oxidative cellular damage play an important role in the pathogenesis of chronic UC and the associated carcinogenetic process. p53Abs levels could help in early detection of dysplasia in these conditions.

CD98 expression modulates intestinal homeostasis, inflammation, and colitis-associated cancer in mice

Expression of the transmembrane glycoprotein CD98 (encoded by SLC3A2) is increased in intestinal inflammatory conditions, such as inflammatory bowel disease (IBD), and in various carcinomas, yet its pathogenetic role remains unknown. By generating gain- and loss-of-function mouse models with genetically manipulated CD98 expression specifically in intestinal epithelial cells (IECs), we explored the role of CD98 in intestinal homeostasis, inflammation, and colitis-associated tumorigenesis. IEC-specific CD98 overexpression induced gut homeostatic defects and increased inflammatory responses to DSS-induced colitis, promoting colitis-associated tumorigenesis in mice. Further analysis indicated that the ability of IEC-specific CD98 overexpression to induce tumorigenesis was linked to its capacity to induce barrier dysfunction and to stimulate cell proliferation and production of proinflammatory mediators. To validate these results, we constructed mice carrying conditional floxed Slc3a2 alleles and crossed them with Villin-Cre mice such that CD98 was downregulated only in IECs. These mice exhibited attenuated inflammatory responses and resistance to both DSS-induced colitis and colitis-associated tumorigenesis. Together, our data show that intestinal CD98 expression has a crucial role in controlling homeostatic and innate immune responses in the gut. Modulation of CD98 expression in IECs therefore represents a promising therapeutic strategy for the treatment and prevention of inflammatory intestinal diseases, such as IBD and colitis-associated cancer.

KCNN4 gene variant is associated with ileal Crohn's Disease in the Australian and New Zealand population

OBJECTIVES

Crohn's disease (CD; MIM 266600) is one of the most common forms of inflammatory bowel disease (IBD), and represents a significant burden to health care in developed countries. Our aim was to determine whether a gene in the IBD linkage region on chromosome 19q13, with a role in Paneth cell secretion and T-cell activation, conferred genetic susceptibility to the development of CD.

METHODS

In total, 792 CD cases and 1,244 controls of Australian origin (Caucasian) were genotyped for seven single-nucleotide polymorphisms (SNPs) in the gene encoding the intermediate conductance calcium-activated potassium channel protein (KCNN4) at 19q13.2. CD cases were phenotyped using the Montreal classification. The replication set comprised an additional 326 CD cases and 951 population-based Caucasian controls. Analysis of the KCNN4 mRNA transcript was carried out using quantitative reverse transcriptase-PCR.

RESULTS

KCNN4 SNP rs2306801 was associated with CD (primary P=0.0008, odds ratio (OR) (95% confidence interval (CI)): 0.76 (0.65-0.89); replication P=0.01, OR (95% CI): 0.77 (0.61-0.97). Stratification by disease location identified the association between SNP rs2306801 and ileal CD (P=0.01). Non-inflamed ileal mucosa from CD patients carrying any of the common disease-predisposing NOD2 variants (R702W, G908R, 1007fs) had significantly reduced levels of KCNN4 mRNA expression (P=0.001). KCNN4 protein expression was detected in Paneth cells, and in T cells in inflamed lamina propria.

CONCLUSIONS

Our data implicate the role of KCNN4 in ileal CD. The dual roles of KCNN4 in Paneth cell secretion and T-cell activation and also its nature as a potassium channel make it an important and practical therapeutic target.

Rapid migration of thymic emigrants to the colonic mucosa in ulcerative colitis patients

Inflammatory bowel disease (IBD) is associated with imbalances of the local intestinal immune responses, with dysregulated CD4(+) T cells contributing to the chronic inflammation. Having demonstrated altered T cell maturation in the thymus in two different mouse models of colitis, we set out to investigate whether abnormalities in T cell maturation is present in patients with ulcerative colitis (UC) or Crohn's disease (CD). Specimens were obtained from peripheral blood (CD; n = 14, UC; n = 22), colon and small intestinal specimens (CD; n = 6, UC; n = 13). As controls, peripheral blood specimens were obtained from healthy volunteers, patients with adenocarcinomas (n = 18) and colonic specimens from patients with adenocarcinomas (n = 14). Recent thymic emigrants were estimated by analysis of the normalized ratio of T cell receptor excision circles (TRECs) by real-time polymerase chain reaction (PCR). The frequency of naive- and proliferating T lymphocytes and markers of extrathymic T cell maturation in the mucosa was analyzed by flow cytometry and real time-PCR. TREC levels in peripheral blood T lymphocytes were similar between IBD patients and controls. In contrast, UC patients demonstrated significantly increased levels of TRECs both in intraepithelial and lamina propria lymphocytes from the colonic mucosa compared to patients with adenocarcinomas and CD. However, markers for extrathymic T cell maturation in the mucosa were not different between controls and IBD patients. The increased TREC levels in mucosal but not peripheral blood lymphocytes in UC patients in the absence of increased extrathymic maturation in situ in the mucosa together demonstrate that recent thymic emigrants are recruited rapidly to the inflamed mucosa of these patients.

MicroRNA-7 modulates CD98 expression during intestinal epithelial cell differentiation

The transmembrane glycoprotein CD98 regulates multiple cellular functions, including extracellular signaling, epithelial cell adhesion/polarity, amino acid transport, and cell-cell interactions. MicroRNAs post-transcriptionally regulate gene expression, thereby functioning as modulators of numerous cellular processes, such as cell differentiation, proliferation, and apoptosis. Here, we investigated if microRNAs regulate CD98 expression during intestinal epithelial cell differentiation and inflammation. We found that microRNA-7 repressed CD98 expression in Caco2-BBE cells by directly targeting the 3'-untranslated region of human CD98 mRNA. Expression of CD98 was decreased, whereas that of microRNA-7 was increased in well-differentiated Caco2-BBE cells compared with undifferentiated cells. Undifferentiated crypt cells isolated from mouse jejunum showed higher CD98 levels and lower levels of mmu-microRNA-706, a murine original microRNA candidate for CD98, than well-differentiated villus cells. Importantly, microRNA-7 decreased Caco2-BBE cell attachment on laminin-1, and CD98 overexpression recovered this inhibition, suggesting that microRNA-7 modulates epithelial cell adhesion to extracellular matrix, which in turn could affect proliferation and differentiation during the migration of enterocytes across the crypt-villus axis, by regulating CD98 expression. In a pathological context, the pro-inflammatory cytokine interleukin 1-beta increased CD98 expression in Caco2-BBE cells by decreasing microRNA-7 levels. Consistent with the in vitro findings, microRNA-7 levels were decreased in actively inflamed Crohn disease colonic tissues, where CD98 expression was up-regulated, compared with normal tissues. Together, these results reveal a novel mechanism underlying regulation of CD98 expression during patho-physiological states. This study raises microRNAs as a promising target for therapeutic modulations of CD98 expression in intestinal inflammatory disorders.

Inflammatory bowel disease: a model of chronic inflammation-induced cancer

Chronic inflammation is a well-recognized risk factor for the development of human cancer. Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a typical longstanding inflammatory disease of the colon with increased risk for the development of colorectal carcinoma. Several molecular events involved in chronic inflammatory process may contribute to multistage progression of human cancer development, including the overproduction of reactive oxygen and nitrogen species, overproduction/activation of key arachidonic acid metabolites and cytokines/growth factors, and immunity system dysfunction. Multiple animal models of IBD have been established, and in general, these models can be mainly categorized into chemically induced, genetically engineered (transgenic or gene knock-out), spontaneous, and adoptive transferring animal models. This chapter mainly focuses on (1) epidemiologic and molecular evidence on IBD and risk of colorectal cancer, (2) molecular pathogenesis of IBD-induced carcinogenesis, and (3) modeling of IBD-induced carcinogenesis in rodents and its application.

Ecto-phosphorylation of CD98 regulates cell-cell interactions

Ecto-phosphorylation plays an important role in many cellular functions. The transmembrane glycoprotein CD98 contains potential phosphorylation sites in its extracellular C-terminal tail. We hypothesized that extracellular signaling through ecto-protein kinases (ePKs) might lead to ecto-phosphorylation of CD98 and influence its multiple functions, including its role in cell-cell interactions. Our results show that recombinant CD98 was phosphorylated in vitro by ePKs from Jurkat cells and by the commercial casein kinase 2 (CK2). Alanine substitutions at serines-305/307/309 or serines-426/430 attenuated CK2-mediated CD98 phosphorylation, suggesting that these residues are the dominant phosphorylation sites for CK2. Furthermore, CD98 expressed in the basolateral membranes of intestinal epithelial Caco2-BBE cells was ecto-phosphorylated by Jurkat cell-derived ePKs and ecto-CK2 was involved in this process. Importantly, cell attachment studies showed that the ecto-phosphorylation of CD98 enhanced heterotypic cell-cell interactions and that the extracellular domain of CD98, which possesses the serine phosphorylation sites, was crucial for this effect. In addition, phosphorylation of recombinant CD98 increased its interactions with Jurkat and Caco2-BBE cells, and promoted cell attachment and spreading. In conclusion, here we demonstrated the ecto-phosphorylation of CD98 by ePKs and its functional importance in cell-cell interactions. Our findings reveal a novel mechanism involved in regulating the multiple functions of CD98 and raise CD98 as a promising target for therapeutic modulations of cell-cell interactions.

Inflammation modulates fibronectin isoform expression in colonic lamina propria fibroblasts (CLPF)

BACKGROUND

Migration of colonic lamina propria fibroblasts (CLPF) plays an important role during mucosal wound healing as well as fibrosis and fistula formation in Crohn's disease (CD). Recently, we showed that the migratory potential of CD-CLPF was significantly reduced compared to control CLPF. Fistula-derived CD-CLPF migrated less and fibrosis-CLPF more than CLPF from inflamed CD mucosa. These changes in migratory behavior were associated with changes in production of the migration-inducing fibronectin (FN) isoforms ED-A and ED-B. A permanent reduction of the migratory potential of CLPF was mediated by IFN-gamma and tumor necrosis factor (TNF) modulate FN isofom expression in CLPF and thereby might regulate CLPF migration.

MATERIALS AND METHODS

Control CLPF were incubated for 72 h with IFN-gamma, TNF, IFN-gamma plus TNF, or TGF-beta1. Messenger RNA (mRNA) was isolated and expression of FN and isoforms ED-A and ED-B was quantified by real-time polymerase chain reaction. FN, ED-A, and ED-B were investigated by Western blotting. FN receptor integrin alpha5beta1 was analyzed by FACS.

RESULTS

No difference was found for the surface display of integrin alpha5beta1 between stimulated and non-stimulated cells. In TGF-beta1 incubated CLPF mRNA amount of FN and isoforms ED-A and ED-B was slightly increased. IFN-gamma only decreased FN in CLPF, TNF significantly reduced FN-mRNA by 40%, FN ED-A mRNA by 25%, and ED-B mRNA by 50%. The TNF-mediated mRNA downregulation resulted in a decreased protein amount as revealed by Western blotting.

CONCLUSION

Cytokines such as IFN-gamma, TNF, and TGF-beta1 modulate the production of fibronectin isoforms. Our data indicate that inflammation-induced modulation of FN-isoform production is involved in the alterations of migratory potential of CLPF isolated from CD mucosa.

Vitamin D derivatives induce apoptosis and downregulate ICAM-1 levels in peripheral blood mononuclear cells of inflammatory bowel disease patients

BACKGROUND

Lymphocytes are crucial in the pathogenesis of inflammatory bowel disease (IBD) and are an important target for drug development. Our aim was to verify whether 2 vitamin D derivatives, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and EB 1089, could induce cell apoptosis and affect cell-cell interaction by regulating adhesion molecule levels.

METHODS

Peripheral blood mononuclear cell (PBMC) proliferation was studied by [3H]thymidine incorporation and apoptosis was determined using an enzyme-linked immunosorbent assay (ELISA) kit. (Poly(ADP-ribose)polymerase (PARP) cleavage, caspase-3, and ICAM-1 protein levels were determined by Western blot analysis.

RESULTS

Our results indicate that 1,25(OH)2D3 or EB 1089 or anti-TNF-alpha (infliximab) induce apoptosis in PBMC obtained from healthy subjects. In IBD patients apoptosis is induced by vitamin D derivatives and by anti-TNF-alpha only in CD patients. Caspase-3 activation and PARP cleavage are registered when PBMC were treated with vitamin D derivatives. ICAM-1 levels remarkably increase when PBMC was incubated with lipopolysaccharide (LPS) or TNF-alpha. The treatment with the vitamin D derivatives, alone or in combination with LPS or TNF-alpha, significantly decreases ICAM-1 levels both in healthy subjects and IBD patients. In HUVEC cocultured with PBMC, previously incubated with LPS or TNF-alpha associated with 1,25(OH)2D3, ICAM-1 levels decrease both in healthy subjects and IBD patients.

CONCLUSIONS

1,25(OH)2D3 and EB 1089 inhibit PBMC proliferation, induce apoptosis in PBMC of healthy subjects and IBD patients, and affect ICAM-1 expression on PBMC and on HUVEC cocultured with PBMC, suggesting that the ICAM-1 downregulation could provide a new target for controlling the recruitment of leukocytes at the sites of inflammation in IBD.

Systematic expression profiling of innate immune genes defines a complex pattern of immunosenescence in peripheral and intestinal leukocytes

Immunosenescence is characterized by a quantitative decline of adequate immune responses, which renders the elderly individual particularly susceptible to bacterial, viral and fungal pathogens. Whereas changes of the aging adaptive immune system (for example, reduced immunoglobulin secretion) have been extensively characterized, alterations of the innate immune system are still poorly understood. The aim of the present study was to systematically examine mRNA expression levels of innate immune genes and proinflammatory cytokines in peripheral and intestinal leukocytes of subjects of different ages. In both, whole blood samples and in colonic biopsies most of the Toll-like receptors (TLRs) and nucleotide-binding and oligomerization domain-like receptors (NLRs) transcript levels were significantly downregulated in elderly subjects (90-99 years). Older individuals, when compared to the younger, exhibited an increased expression and/or secretion of proinflammatory cytokines by peripheral and intestinal leukocytes as well as an increased level of nuclear factor-kappaB activation in colonic biopsies. The observed downregulation of TLRs and NLRs during the aging process may contribute to the lack of effective recognition of invading pathogens or the commensal flora. This effect results in aberrant secondary immune cell activation and could significantly contribute to morbidity and mortality at advanced age.

Bacterial superantigens and T cell receptor beta-chain-bearing T cells in the immunopathogenesis of ulcerative colitis

Ulcerative colitis (UC) is a chronic relapsing-remitting inflammatory bowel disease (IBD) that affects the colon and the rectum producing debilitating symptoms, which impair ability to function and quality of life. The aetiology of IBD is incompletely understood, but within the lymphocyte population, specific T cell subsets are known to be major factors in the development of intestinal immune pathology while different subsets are essential regulators, controlling IBD. Hence, IBD is thought to reflect dysregulated T cell behaviour. This study was to investigate if the normal molecular configuration of the T cell receptor (TCR) repertoire is compromised in patients with UC. The percentage of T cell-bearing beta-chain 4 (TCRBV4) was high in patients with UC, and T cells showed polyclonal expansion in the presence of bacterial superantigens (SA) such as streptococcal mitogenic exotoxin Z-2 (SMEZ-2), indicating that bacterial SA promote specific TCRBV family expansion. Further, in patients with UC, the duration of UC was significantly longer in patients with skewed TCRBV4 compared with patients without TCRBV4 skewing, suggesting that long-term exposure to bacterial SA such as SMEZ-2 might promote systemic immune disorders like the remission-relapsing cycles seen in patients with UC. In conclusion, our observations in this study support the perception that the systemic activation of T cells by enteric bacterial SA might lead to a dysregulated, but exuberant immune activity causing the remission and flare-up cycle of mucosal inflammation in patients with UC. Future studies should strengthen our findings and increase understanding on the aetiology of IBD.

Oxidative DNA damage and antioxidant activity in patients with inflammatory bowel disease

Chronic inflammation may contribute to cancer risk through the accumulation of specific products as a result of DNA damage. Endogenous antioxidant enzymes prevent the formation of these harmful products. Oxidative DNA damage and endogenous antioxidant defense were determined in patients with inflammatory bowel disease (IBD). Plasma levels of 8-hydroxydeoxyguanosine (8-OHdG) and nitric oxide (NO) and plasma activities of glutathione peroxidase (G-Px) and superoxide dismutase (SOD) were determined in patients with IBD by ELISA and spectrophotometric assay, respectively. Plasma levels of 8-OHdG, SOD, and G-Px activity were found to be increased in the patient group compared to the control group (P < 0.02, P < 0.001, and P < 0.001, respectively), whereas NO was unchanged. 8-OHdG level was found to be weakly correlated with age, NO, and SOD. The results show increased DNA damage in patients with IBD. This may explain the increased risk of developing colon cancer in these patients.

Lactobacilli, bifidobacteria and E. coli nissle induce pro- and anti-inflammatory cytokines in peripheral blood mononuclear cells

AIM: To investigate whether the stimulation of peripheral blood mononuclear cells (PBMNC) with the cell debris and cell extraction of different probiotic strains is similar or species specific.

METHODS: Three strains of bifidobacteria, 4 strains of lactobacilli, and E. coli nissle were sonicated and centrifuged in order to divide them into cell extract and cell debris. PBMNC were separated by density gradient and incubated for 36 h with either the cell debris or the cell extract of single strains of probiotic bacteria in doses from 10² to 10⁸ CFU/mL. Cell supernatants were taken and interleukin (IL)-10, IL-1β, and tumor necosis factor (TNF)-α were determined by ELISA.

RESULTS: Depending on the species super-family, the strains had different stimulation patterns. Except for both L. casei strains, the cell extract of bifidobacteria and lactobacilli had less stimulating capacity than cell debris, whereas the cell extract of E. coli nissle had similar stimulating properties to that of the cell debris of the strain and significantly more stimulating capacity than that of bifidobacteria and lactobacilli. The cell debris of bifidobacteria stimulated more cytokine release than the cell debris of lactobacilli. The cell debris of lactobacilli did not have a stimulating capacity when lower concentrations were used. Neither cell extraction nor cell debris had an inhibitory effect on the production of the tested cytokines by stimulated PBMNC.

CONCLUSION: The incubation of probiotic strains, which have been used in clinical trials for inflammatory diseases, with immunocompetent cells leads to different species specific reactions. High IL-10 response to cell debris of bifidobacteria and E. coli nissle can be found. This corresponds to positive effects of bifidobacteria and E. coli nissle in clinical trials for inflammatory bowel disease compared to negative outcomes obtained with lactobacilli.

Irinotecan changes gene expression in the small intestine of the rat with breast cancer

PURPOSE

The aetiology of mucositis is complex involving change in gene expression, altered apoptosis and interaction between epithelial and subepithelial compartments. This is the first investigation using microarray to assess chemotherapy-induced changes in the gut. The aims of this study were to identify genes that are altered by irinotecan, to determine how these genes contribute to apoptosis and to identify any potential gene families and pathways that are important for mucositis development.

METHODS

Tumour-bearing female dark Agouti rats were administered twice with 150 mg/kg of irinotecan and killed 6 h after the final dose. Jejunal tissue was harvested and RNA was isolated. cDNA was synthesised and purified, prior to hybridisation and microarray analysis. A 5-K oligo clone set was used to investigate gene expression. Results from the microarray were quantified using RT-PCR.

RESULTS

Many genes were significantly up- or down-regulated by irinotecan. In particular, multiple genes implicated in the mitogen-activated protein kinase (MAPK) signalling pathway were differentially regulated following treatment. These included interleukin 1 receptor, caspases, protein kinase C and dual-specificity phosphatase 6. RT-PCR was used to confirm effects of irinotecan on caspase-1 expression in jejunal tissue and was significantly increased 6 h after treatment with irinotecan.

CONCLUSIONS

This study has identified MAP kinase signalling as being involved with irinotecan-induced intestinal damage and confirms previous findings with radiation-induced oral mucosal damage, which also implicated this pathway. Microarrays are emerging as a valuable tool in mucositis research by linking such findings. The common pathway of chemotherapy- and radiotherapy-induced damage, which utilises the caspase-cascade, may be a useful target to prevent apoptosis following cancer treatment.

The influence of different management systems and age on intestinal morphology, immune cell numbers and mucin production from goblet cells in post-weaning pigs

At time of weaning, the immune system in piglets is not fully mature resulting in reduced growth and increased mortality. Early-weaned pigs transported to a segregated early weaning (SEW) facility have enhanced performance and gut development compared to conventional (CONV) pigs which may be due, in part, to decreased pathogen challenge. To gain further insight into SEW enhanced performance and gut development, gut samples from pigs weaned at 19+/-2 days were assessed during the post-weaning (PW) period. The numbers of cells expressing CD2, CD4, CD8, and CD172 (the 74-22-15 (SWC3) antibody is now known to be specific for CD172), MHC class II, and CD25 were quantified using immunohistochemistry. Additionally, samples of duodenum, jejunum, and ileum were evaluated for the production of neutral, acidic, and sulfuric mucins from goblet cells and morphological measurements were also made. No effects due to the management systems alone were observed for any of the parameters. However, there were interactive effects of age/time post-weaning and management system on the immune cells as well as on the mucin secreting goblet cells. There were no differences in gut morphology between SEW and CONV reared pigs.

Interaction among vitamin D(3) analogue KH 1060, TNF-alpha, and vitamin D receptor protein in peripheral blood mononuclear cells of inflammatory bowel disease patients

BACKGROUND

The active form of vitamin D, 1,25(OH)(2)D(3), exerts important effects on proliferation and differentiation of many cell types, and immunoregulatory activities in particular on T cell-mediated immunity.

AIM

The aim of this study was to investigate whether KH 1060, a vitamin D analogue, could decrease tumor necrosis factor-alpha (TNF-alpha) levels in patients with inflammatory bowel disease (IBD).

METHODS

PBMC proliferation was determined by [(3)H]thymidine incorporation. TNF-alpha levels were measured by ELISA kit; VDR, Bcl-2 and Bax protein levels with Western blot analysis.

RESULTS

KH 1060 inhibited PBMC proliferation and decreased TNF-alpha levels in IBD patients and this effect was synergistic with anti-TNF-alpha. VDR protein levels were significantly increased by PBMC treatment with KH 1060 or anti-TNF-alpha or their combination in ulcerative colitis (UC) patients, and decreased in Crohn's disease (CD) patients, treating the cells with KH 1060. In UC patients an increase in Bcl-2 and Bax levels was observed incubating, PBMC with KH 1060 or anti-TNF-alpha or their combination. In CD patients a slight decrease in Bcl-2 levels was registered when anti-TNF alone or in association with KH 1060 was used. Bax protein levels were slightly increased in the presence of KH 1060 alone or in combination with anti-TNF.

CONCLUSION

This study shows that KH 1060 acts as an immunomodulator on PBMC, acting as TNF-alpha inhibitor. This finding provides strong evidence that vitamin D status could be an important regulator of immunity IBD.

Intestinal macrophages: unique effector cells of the innate immune system

The gastrointestinal mucosa is the largest reservoir of macrophages in the body. These important effector cells are derived from blood monocytes that are recruited to the lamina propria by endogenous chemoattractants in the non-inflamed mucosa and by inflammatory chemokines and bacterial products during inflammation. In the non-inflamed mucosa, newly recruited pro-inflammatory monocytes are exposed to lamina propria stromal (extracellular matrix) factors that induce phenotypic and functional differentiation into non-inflammatory macrophages. As a consequence of this differentiation, resident lamina propria macrophages are strikingly downregulated for the expression of innate response receptors, such as the receptors for lipopolysaccharide, immunoglobulin G (IgG), and IgA, and the production of pro-inflammatory cytokines, including interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor-alpha. Despite downregulated pro-inflammatory function, strong phagocytic and bactericidal activities remain intact. Thus, in the non-inflamed intestinal mucosa, lamina propria macrophages are non-inflammatory but retain avid scavenger and host defense functions, a unique but ideal phenotype and functional profile for effector cells in close proximity to immunostimulatory microorganisms and products.

Activation of epithelial CD98 glycoprotein perpetuates colonic inflammation

Anomalies in the regulation and function of integrins have been implicated in the etiology of various pathologic conditions, including inflammatory disorders such as irritable bowel disease. Several classes of cell surface glycoproteins such as CD98 have been shown to play roles in integrins-mediated events. Here, we investigated the role of CD98 in intestinal inflammation using both in vivo and in vitro approaches. We found that in Caco2-BBE monolayers and colonic tissues, expression of CD98 was upregulated by the proinflammatory cytokine, interferon gamma (INF gamma). Furthermore, CD98 was highly upregulated in colonic tissues from mice with active colitis induced by dextran sodium sulfate (DSS), but not in DSS-treated INF gamma -/- mice. Administration of an anti-CD98 antibody worsened DSS-induced colitis in mice but had no effect on untreated control mice. Finally, we used Caco2-BBE cell monolayers to model intestinal epithelial wound healing, and found that activation of epithelial CD98 in DSS-treated monolayers inhibited monolayer reconstitution, but had no affect on untreated control monolayers. Our data collectively indicate that (i) CD98 upregulation is mediated by INF gamma during intestinal inflammation and (ii) activation of epithelial CD98 protein aggravates intestinal inflammation by reducing intestinal epithelial reconstitution. Overall, our data suggest that epithelial CD98 plays an important role in the perpetuation of intestinal inflammation.

Peripheral and intestinal regulatory CD4+ CD25(high) T cells in inflammatory bowel disease

BACKGROUND & AIMS

Regulatory CD25+ T cells (T(reg)) are effective in the prevention and down-regulation of inflammatory bowel disease (IBD) in animal models. Functional T(reg) cells are characterized by the expression of the transcription factor FOXP3 and show a CD4+ CD25(high) phenotype in humans. The aim of this study was to determine whether disease activity in IBD correlates with changes in frequency of T(reg) cells and their distribution in the intestinal mucosa.

METHODS

T(reg) cells were analyzed from peripheral blood and from biopsy specimens of IBD patients, inflammatory controls, and healthy volunteers by flow cytometry (CD4+ CD25(high)), immunochemistry (FOXP3), and real-time PCR (FOXP3). Regulatory properties of purified peripheral CD4+ CD25(high) T(reg) cells were determined by their suppressive effect on the proliferation of CD4+ CD25- T cells.

RESULTS

In peripheral blood, CD4+ CD25(high) T cells from IBD patients retain their suppressive activity. CD4+ CD25(high) and FOXP3+ T(reg) cells are increased during remission but decreased during active disease. This contrasts with their strong increase in peripheral blood of patients with acute diverticulitis. Different than peripheral blood, inflamed IBD mucosa contains an increased number of CD4+ CD25(high) T cells, FOXP3+ T cells, and transcripts for FOXP3 compared with noninflamed mucosa. However, the increase of FOXP3+ T cells in IBD lesions is significantly lower compared with inflammatory controls.

CONCLUSIONS

The frequency of CD4+ CD25+ T(reg) cells varies with IBD activity. Active IBD is not associated with a functional defect but with a contraction of the peripheral blood T reg pool and an only moderate expansion in intestinal lesions. Thus, compensatory mechanisms, numerically, are not successfully achieved in these diseases.

Effects of infliximab on apoptosis and reverse signaling of monocytes from healthy individuals and patients with Crohn's disease

OBJECTIVES

Infliximab, an anti-tumor necrosis factor (TNF) monoclonal antibody, might exert some of its long-term therapeutic effects in Crohn's disease (CD) by interacting directly with cells of the immune system such as monocytes and T lymphocytes via membrane TNF and by inducing apoptosis. Accordingly, the effects of inflix-imab on monocyte apoptosis and down-regulation of proinflammatory cytokines (reverse signaling) were assessed.

METHODS

To assess apoptosis, monocytes from healthy individuals (controls) and CD patients were incubated in the presence or absence of infliximab or the apoptotic agent gliotoxin for 24 hours. Annexin V staining and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-FITC nick end labeling assay were used to measure early and late apoptosis. To measure the effects of infliximab on reverse signaling, monocytes from healthy individuals pretreated in vitro with infliximab were stimulated with lipopolysaccharide or staphylococcal enterotoxin A, and the induction of the proinflammatory cytokines, TNF-alpha, interleukin (IL)-1beta, IL-6, and IL-8 was measured by reverse transcription polymerase chain reaction. The effect of in vivo infliximab treatment of monocytes was similarly determined by comparing the responses of monocytes from CD patients before and immediately after infliximab infusion.

RESULTS

Infliximab did not induce apoptosis of monocytes from either healthy individuals or CD patients but rather stabilized them. However, monocytes from healthy individuals treated with infliximab in vitro, or from CD patients infused with infliximab, produced significantly less TNF and other proinflammatory cytokines when stimulated with the bacterial products lipopolysaccharide and staphylococcal enterotoxin A.

CONCLUSIONS

Apoptosis of monocytes is not responsible for the therapeutic effects of infliximab. However, some of the therapeutic effects of infliximab may be caused by its ability to down-regulate proinflammatory cytokines production by monocytes exposed to bacterial antigens.

Review article: exploration of the genetic aetiology of inflammatory bowel disease--implications for diagnosis and therapy

Genomic technologies offer new approaches to the investigation of the aetiology and pathophysiology of inflammatory bowel disease. An important field relevant to inflammatory bowel disease therapy is the pharmacogenetic investigation of gene variations that may predict responses to certain medications in order to target these therapeutic interventions more precisely. To date, only about 12,000 of the estimated 30,000-50,000 human genes have been characterized. Therefore, the use of techniques for a global analysis of gene expression may allow the identification of new pathways or molecules in the therapeutic mechanisms of drugs. Recently, NOD2 has been identified as the first disease gene in inflammatory bowel disease. DLGS and OCTN-1 have been named as further disease genes. Although the detection of disease-associated variants has greatly advanced our understanding of the primary events that lead to the development of inflammatory bowel disease in a subgroup of patients with Crohn's disease, the implications of the findings for diagnostic and therapeutic algorithms are less clear. However, it appears that there is a clear association between certain subphenotypes of Crohn's disease and the disease-associated variants in the NOD2 gene. It can be anticipated that genomic findings will profoundly influence the future therapy of inflammatory bowel disease.

CD40-mediated immune-nonimmune cell interactions induce mucosal fibroblast chemokines leading to T-cell transmigration

BACKGROUND AND AIMS

The CD40 pathway is a key mediator of inflammation and autoimmunity. We investigated cell adhesion molecule (CAM) up-regulation and chemokine production by CD40-positive human intestinal fibroblasts (HIF) and microvascular endothelial cells (HIMEC) induced by CD40 ligand (CD40L)-positive T cells and soluble CD40L and their effect on T-cell adhesion and transmigration.

METHODS

Expression of CD40, CD40L, and CAM was assessed by immunohistochemistry, confocal microscopy and flow cytometric analysis, and chemokine production using enzyme-linked immunosorbent assay. Calcein-labeled T cells were used to assay HIF adhesion and Transwell HIMEC transmigration.

RESULTS

Ligation of CD40-positive HIF and HIMEC by CD40L-positive T cells or soluble CD40L induced up-regulation of CAM expression as well as interleukin-8 and RANTES production. The specificity of these responses was shown by inhibition with a CD40L blocking antibody and by CD40 signaling-dependent p38 mitogen-activated protein kinase phosphorylation. On CD40 ligation, HIF increased their T-cell binding capacity and generated chemoattractants able to induce T-cell migration through HIMEC monolayers.

CONCLUSIONS

Activation of the CD40/CD40L system in the gut mucosa may trigger a self-sustaining loop of immune-nonimmune cell interactions leading to an antigen-independent influx of T cells that contributes to chronic inflammation.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Galectin-1 suppresses experimental colitis in mice

BACKGROUND & AIMS

Uncontrolled T-cell activation plays a critical role in the pathogenesis of inflammatory bowel diseases. Therefore, pharmacologic strategies directed to restore the normal responsiveness of the immune system by deleting inappropriately activated T cells could be efficacious in the treatment of these pathologic conditions. Galectin-1 is an endogenous lectin expressed in lymphoid organs that plays a role in the maintenance of central and peripheral tolerance. The aim of the present study was to evaluate the therapeutic effects of galectin-1 on T-helper cell type 1-mediated experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice.

METHODS

Cells and tissues from mice with TNBS colitis receiving treatment with several doses of human recombinant galectin-1 (hrGAL-1) were analyzed for morphology, cytokine production, and apoptosis.

RESULTS

Prophylactic and therapeutic administration of rhGAL-1 resulted in a striking improvement in the clinical and histopathologic aspects of the disease. hrGAL-1 reduced the number of hapten-activated spleen T cells, decreased inflammatory cytokine production, and profoundly reduced the ability of lamina propria T cells to produce IFN gamma in vitro. Moreover, hrGAL-1 led to the appearance of apoptotic mononuclear cells in colon tissue when administered in vivo and induced selective apoptosis of TNBS-activated lamina propria T cells in vitro.

CONCLUSION

Collectively, these data show that hrGAL-1 exerts protective and immunomodulatory activity in TNBS-induced colitis and it might be effective in the treatment of inflammatory bowel diseases.

Novel therapies in the treatment of ulcerative colitis

Ulcerative colitis is a chronic inflammatory disease of the colon of unknown cause. Its course is one of relapse and remission and requires therapy for both the induction and maintenance of remission. Progress in the fields of genetics and immunology affords important advances in our understanding of the inflammatory process. Traditional therapy for ulcerative colitis with nonspecific anti-inflammatories remains our gold standard. This review examines the most recent compounds in development for the treatment of ulcerative colitis, including data from early clinical trials and the potential clinical impact of future entities.

IL-10 producing CD14low monocytes inhibit lymphocyte-dependent activation of intestinal epithelial cells by commensal bacteria

Intestinal epithelial cell (IEC) activation by non-pathogenic, commensal bacteria was demonstrated to require the presence of immunocompetent cells. In this study, HT-29 and CaCO-2 transwell cultures, reconstituted with CD4+ and CD8+ T cells, CD19+ B cells and CD14high monocytes, were challenged with non-pathogenic Gram negative Escherichia coli and Gram positive lactobacilli. Cytokine expression was analysed by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assays (ELISA). Expression of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-8 mRNA in E. coli or L. sakei challenged IEC was promoted by lymphocyte populations predominantly CD4+ T cells, while monocytes failed to mediate an inflammatory cytokine response. The monocyte phenotype and function were further characterised by flow cytometry and mixed lymphocyte reaction (MLR). During the co-culture with IEC and bacterial stimulated IEC, CD14high peripheral blood monocytes acquired a CD14low CD16low phenotype with reduced expression co-stimulatory (CD80, CD86, CD58) cell surface molecules. Immunosuppressive functions of IEC conditioned CD14low monocytes were demonstrated by the predominant secretion of IL-10 and IL-IRa and their reduced potential to trigger an allogeneic lymphocyte response. In conclusion, IEC contribute to the development of CD14low CD16low monocytes with immunosuppressive function and antagonised a lymphocyte-mediated activation of the intestinal epithelium in response to intestinal and food derived bacteria. These results strengthen the hypothesis that the gut epithelium constitutes an important functional element in the regulation of mucosal immune homeostasis towards commensal bacteria.