Quantitative and functional characteristics of intestinal-homing memory T cells: analysis of Crohn's disease patients and healthy controls

Epithelial barrier dysfunction and microbial dysbiosis: exploring the pathogenesis and therapeutic strategies for Crohn's disease

Crohn's disease (CD), a chronic gastrointestinal inflammatory disease, is becoming more widespread worldwide. Crohn's disease is caused by gut microbiota changes, genetics, environmental stresses, and immunological responses. Current treatments attempt to achieve long-term remission and avoid complications, delaying disease progression. Immunosuppressive measures and combination medicines should be started early for high-risk patients. These medicines monitor inflammatory indicators and adjust as needed. The epithelial barrier helps defend against physical, chemical, and immunological threats. When tissues' protective barrier breaks down, the microbiome may reach the layer underneath. Unbalanced microbial populations and inflammation impair healing and adjustment. Inflammatory cells infiltrating sensitive tissues aggravate the damage and inflammation. This approach promotes chronic inflammatory diseases. The epithelial barrier hypothesis states that hereditary and environmental variables cause epithelial tissue inflammation. This review focuses on how epithelial barrier break-down and microbial dysbiosis cause Crohn's disease and current advances in understanding the epithelial barrier, immune system, and microbiome. Additionally, investigate treatments that restore barrier integrity and promote microbial balance. Overall, it stresses the role of epithelial barrier failure and microbial dysbiosis in Crohn's disease development and discusses current advances in understanding the barrier, immunological responses, and microbiota.

Human Dendritic Cells: Ontogeny and Their Subsets in Health and Disease

Dendritic cells (DCs) are a type of cells derived from bone marrow that represent 1% or less of the total hematopoietic cells of any lymphoid organ or of the total cell count of the blood or epithelia. Dendritic cells comprise a heterogeneous population of cells localized in different tissues where they act as sentinels continuously capturing antigens to present them to T cells. Dendritic cells are uniquely capable of attracting and activating naïve CD4⁺ and CD8⁺ T cells to initiate and modulate primary immune responses. They have the ability to coordinate tolerance or immunity depending on their activation status, which is why they are also considered as the orchestrating cells of the immune response. The purpose of this review is to provide a general overview of the current knowledge on ontogeny and subsets of human dendritic cells as well as their function and different biological roles.

Compartment-specific immunity in the human gut: properties and functions of dendritic cells in the colon versus the ileum

OBJECTIVE

Dendritic cells (DC) mediate intestinal immune tolerance. Despite striking differences between the colon and the ileum both in function and bacterial load, few studies distinguish between properties of immune cells in these compartments. Furthermore, information of gut DC in humans is scarce. We aimed to characterise human colonic versus ileal DC.

DESIGN

Human DC from paired colonic and ileal samples were characterised by flow cytometry, electron microscopy or used to stimulate T cell responses in a mixed leucocyte reaction.

RESULTS

A lower proportion of colonic DC produced pro-inflammatory cytokines (tumour necrosis factor-α and interleukin (IL)-1β) compared with their ileal counterparts and exhibited an enhanced ability to generate CD4(+)FoxP3(+)IL-10(+) (regulatory) T cells. There were enhanced proportions of CD103(+)Sirpα(-) DC in the colon, with increased proportions of CD103(+)Sirpα(+) DC in the ileum. A greater proportion of colonic DC subsets analysed expressed the lymph-node-homing marker CCR7, alongside enhanced endocytic capacity, which was most striking in CD103(+)Sirpα(+) DC. Expression of the inhibitory receptor ILT3 was enhanced on colonic DC. Interestingly, endocytic capacity was associated with CD103(+) DC, in particular CD103(+)Sirpα(+) DC. However, expression of ILT3 was associated with CD103(-) DC. Colonic and ileal DC differentially expressed skin-homing marker CCR4 and small-bowel-homing marker CCR9, respectively, and this corresponded to their ability to imprint these homing markers on T cells.

CONCLUSIONS

The regulatory properties of colonic DC may represent an evolutionary adaptation to the greater bacterial load in the colon. The colon and the ileum should be regarded as separate entities, each comprising DC with distinct roles in mucosal immunity and imprinting.

Human gut dendritic cells drive aberrant gut-specific t-cell responses in ulcerative colitis, characterized by increased IL-4 production and loss of IL-22 and IFNγ

: The pathogenesis of inflammatory bowel disease is incompletely understood but results from a dysregulated intestinal immune response to the luminal microbiota. CD4 T cells mediate tissue injury in the inflammatory bowel disease-associated immune response. Dendritic cells (DC) generate primary T-cell responses and mediate intestinal immune tolerance to prevent overt inflammation in response to the gut microbiota. However, most information regarding function of intestinal DC has come from mouse models, and information in humans is scarce. We show here that intestinal DC subsets are skewed in ulcerative colitis (UC) in humans, with a loss of CD103 lymph-node homing DC; this intestinal DC subset preferentially generates regulatory T cells in mice. We show infiltrates of DC negative for myeloid marker CD11c, with enhanced expression of Toll-like receptors for bacterial recognition. After mixed leukocyte reaction, DC from the inflamed UC colon had an enhanced ability to generate gut-specific CD4 T cells with enhanced production of interleukin-4 but a loss of interferon γ and interleukin-22 production. Conditioning intestinal DC with probiotic strain Lactobacillus casei Shirota in UC partially restored their normal function indicated by reduced Toll-like receptor 2/4 expression and restoration of their ability to imprint homing molecules on T cells and to generate interleukin-22 production by stimulated T cells. This study suggests that T-cell dysfunction in UC is driven by DC. T-cell responses can be manipulated indirectly through effects of bacterial conditioning on gut DC with implications for immunomodulatory effects of the commensal microbiota in vivo. Manipulation of DC to allow generation of DC-specific therapy may be beneficial in inflammatory bowel disease.

Altered intestinal microbiota and blood T cell phenotype are shared by patients with Crohn's disease and their unaffected siblings

OBJECTIVE

Crohn's disease (CD) is associated with intestinal dysbiosis, altered blood T cell populations, elevated faecal calprotectin (FC) and increased intestinal permeability (IP). CD-associated features present in siblings (increased risk of CD) but not in healthy controls, provide insight into early CD pathogenesis. We aimed to (1) Delineate the genetic, immune and microbiological profile of patients with CD, their siblings and controls and (2) Determine which factors discriminate between groups.

DESIGN

Faecal microbiology was analysed by quantitative PCR targeting 16S ribosomal RNA, FC by ELISA, blood T cell phenotype by flow cytometry and IP by differential lactulose-rhamnose absorption in 22 patients with inactive CD, 21 of their healthy siblings and 25 controls. Subject's genotype relative risk was determined by Illumina Immuno BeadChip.

RESULTS

Strikingly, siblings shared aspects of intestinal dysbiosis with patients with CD (lower concentrations of Faecalibacterium prausnitzii (p=0.048), Clostridia cluster IV (p=0.003) and Roseburia spp. (p=0.09) compared with controls). As in CD, siblings demonstrated a predominance of memory T cells (p=0.002) and elevated naïve CD4 T cell β7 integrin expression (p=0.01) compared with controls. FC was elevated (>50 μg/g) in 8/21 (38%) siblings compared with 2/25 (8%) controls (p=0.028); whereas IP did not differ between siblings and controls. Discriminant function analysis determined that combinations of these factors significantly discriminated between groups (χ(2)=80.4, df=20, p<0.001). Siblings were separated from controls by immunological and microbiological variables.

CONCLUSIONS

Healthy siblings of patients with CD manifest immune and microbiological abnormalities associated with CD distinct from their genotype-related risk and provide an excellent model in which to investigate early CD pathogenesis.

Dysregulated circulating dendritic cell function in ulcerative colitis is partially restored by probiotic strain Lactobacillus casei Shirota

BACKGROUND

Dendritic cells regulate immune responses to microbial products and play a key role in ulcerative colitis (UC) pathology. We determined the immunomodulatory effects of probiotic strain Lactobacillus casei Shirota (LcS) on human DC from healthy controls and active UC patients.

METHODS

Human blood DC from healthy controls (control-DC) and UC patients (UC-DC) were conditioned with heat-killed LcS and used to stimulate allogeneic T cells in a 5-day mixed leucocyte reaction.

RESULTS

UC-DC displayed a reduced stimulatory capacity for T cells (P < 0.05) and enhanced expression of skin-homing markers CLA and CCR4 on stimulated T cells (P < 0.05) that were negative for gut-homing marker β7. LcS treatment restored the stimulatory capacity of UC-DC, reflecting that of control-DC. LcS treatment conditioned control-DC to induce CLA on T cells in conjunction with β7, generating a multihoming profile, but had no effects on UC-DC. Finally, LcS treatment enhanced DC ability to induce TGFβ production by T cells in controls but not UC patients.

CONCLUSIONS

We demonstrate a systemic, dysregulated DC function in UC that may account for the propensity of UC patients to develop cutaneous manifestations. LcS has multifunctional immunoregulatory activities depending on the inflammatory state; therapeutic effects reported in UC may be due to promotion of homeostasis.

Skin- and gut-homing molecules on human circulating γδ T cells and their dysregulation in inflammatory bowel disease

Changes in phenotype and function of γδ T cells have been reported in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Dysregulation of lymphocyte migration plays a key role in IBD pathogenesis; however, data on migratory properties of γδ T cells are scarce. Human circulating γδ T cells from healthy controls (n = 27), patients with active CD (n = 15), active UC (n = 14) or cutaneous manifestations of IBD (n = 2) were characterized by flow cytometry. Circulating γδ T cells in healthy controls were CD3(hi) and expressed CD45RO. They expressed gut-homing molecule β7 but not gut-homing molecule corresponding chemokine receptors (CCR)9, or skin-homing molecules cutaneous lymphocyte-associated antigen (CLA) and CCR4, despite conventional T cells containing populations expressing these molecules. CCR9 expression was increased on γδ T cells in CD and UC, while skin-homing CLA was expressed aberrantly on γδ T cells in patients with cutaneous manifestations of IBD. Lower levels of CD3 expression were found on γδ T cells in CD but not in UC, and a lower proportion of γδ T cells expressed CD45RO in CD and UC. Enhanced expression of gut-homing molecules on circulating γδ T cells in IBD and skin-homing molecules in cutaneous manifestations of IBD may be of clinical relevance.

Intestinal dendritic cells: their role in intestinal inflammation, manipulation by the gut microbiota and differences between mice and men

The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota and food antigens. Dendritic cells (DC) generate primary T-cell responses, and determine whether these responses are immunogenic or tolerogenic. The regulatory role of DC is of particular importance in the gut due to the high antigenic load. Intestinal DC act as sentinels, sampling potentially pathogenic antigens but also harmless antigens including the commensal microbiota. Following antigen acquisition, intestinal DC migrate to secondary lymphoid organs to activate naive T-cells. DC also imprint specific homing properties on T-cells that they stimulate; gut DC specifically induce gut-homing properties on T-cells upon activation, enabling T-cell migration back to intestinal sites. Data regarding properties on gut DC in humans is scarce, although evidence now supports the role of DC as important players in intestinal immunity in humans. Here, we review the role of intestinal DC in shaping mucosal immune responses and directing tissue-specific T-cell responses, with a special focus on the importance of distinguishing DC subsets from macrophages at intestinal sites. We compare and contrast human DC with their murine counterparts, and discuss the ability of the gut microbiota to shape intestinal DC function, and how this may be dysregulated in inflammatory bowel disease (IBD). Lastly, we describe recent advances in the study of probiotics on intestinal DC function, including the use of soluble secreted bacterial products.

IL-6 promotes immune responses in human ulcerative colitis and induces a skin-homing phenotype in the dendritic cells and Tcells they stimulate

Dendritic cells (DCs) control the type and location of immune responses. Ulcerative colitis (UC) is considered a Th2 disease mediated by IL-13 where up to one third of patients can develop extraintestinal manifestations. Colonic biopsies from inflamed and noninflamed areas of UC patients were cultured in vitro and their supernatants were used to condition human blood enriched DCs from healthy controls. Levels of IL-13 in the culture supernatants were below the detection limit in most cases and the cytokine profile suggested a mixed profile rather than a Th2 cytokine profile. IL-6 was the predominant cytokine found in inflamed areas from UC patients and its concentration correlated with the Mayo endoscopic score for severity of disease. DCs conditioned with noninflamed culture supernatants acquired a regulatory phenotype with decreased stimulatory capacity. However, DCs conditioned with inflamed culture supernatants acquired a proinflammatory phenotype with increased expression of the skin-homing chemokine CCR8. These DCs did not have decreased T-cell stimulatory capacity and primed T cells with the skin-homing CLA molecule in an IL-6-dependent mechanism. Our results highlight the role of IL-6 in UC and question the concept of UC as a Th2 disease and the relevance of IL-13 in its etiology.

Bacterial induction of proinflammatory cytokines in inflammatory bowel disease

It has become increasingly clear that inflammatory bowel disease (IBD) develops on the background of genetic defects in the host, conveying an increased susceptibility to an environmental antigen or antigens. The environmental factor implicated in the pathophysiology of gut inflammation, which is undergoing increased scrutiny, is the intestinal flora. The intestinal flora as a whole and specific bacteria and their products have been found to trigger cytokine expression in various cell types. Consistently, multiple bacterial strains were found to induce tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) in macrophage and epithelial cell systems, respectively, in particular in Crohn's disease. Interestingly, various cell types from patients with IBD display an increased susceptibility to specific bacterial products, including flagellin, pili, and lipopolysaccharides. It remains to be determined whether additional effector proteins regulate cytokine expression and the aberrant mucosal immune response in IBD.

Homing of immune cells: role in homeostasis and intestinal inflammation

Rather like a satellite navigation system directing a vehicle to a particular destination defined by post-code, immune cells have homing molecules or "immune post-codes" enabling them to be recruited to specific organs, such as the intestine or skin. An efficient system would be designed such that the site of entry of an antigen influences the homing of effector T cells back to the appropriate organ. For example, to mount an immune response against an intestinal pathogen, T cells with a propensity to home to the gut to clear the infection would be induced. In health, there is such a sophisticated and finely tuned system in operation, enabling an appropriate balance of immune activity in different anatomical compartments. In disease states such as inflammatory bowel disease (IBD), which is characterized by intestinal inflammation and often an inflammatory process involving other organs such as skin, joints, liver, and eye, there is accumulating evidence that there is malfunction of this immune cell trafficking system. The clinical importance of dysregulated immune cell trafficking in IBD is reflected in recently proven efficacious therapies that target trafficking pathways such as natalizumab, an α4 integrin antibody, and Traficet-EN, a chemokine receptor-9 (CCR9) antagonist. Here we review the mechanisms involved in the homing of immune cells to different tissues, in particular the intestine, and focus on alterations in immune cell homing pathways in IBD. Unraveling the mechanisms underlying the immune post-code system would assist in achieving the goal of tissue-specific immunotherapy.

Discrete changes in circulating regulatory T cells during infliximab treatment of Crohn's disease

Deficiency of CD4+CD25+ regulatory T cells (Tregs) may be involved in Crohn's disease (CD) pathogenesis. In rheumatoid arthritis (RA), the anti-TNF-alpha antibody infliximab increases circulating Treg numbers. We aimed to evaluate circulating Tregs in CD before and after infliximab therapy. In 20 patients with active CD, blood samples were obtained before infusion of infliximab 5 mg/kg and 1, 7, and 42 days after therapy. Clinical, biochemical, and fecal markers of inflammation were obtained. Nine healthy volunteers served as controls. We applied a novel Treg marker, the absence of CD127 expression, to identify Tregs by whole-blood flow cytometry. Treg percentages were similar among CD patients [median 7.7%, interquartile range (IQR) 5.3-10.1%] and healthy volunteers (median 7.6% IQR 6.3-8.9%) with discrete changes (median 7.3%, IQR 4.5-10.1%) throughout the study period, irrespective of the significant clinical effect of infliximab. Unlike in RA, we found no arising population of CD62L - Tregs; however, we observed a rapid recruitment of lymphocytes and upregulation of the intestinal homing marker alpha4beta7 integrin on CD4+T cells. In conclusion, our results do not support the hypothesis that the clinical effect of infliximab is mediated by a reinforcement of defective, circulating Tregs in CD.

Diminution of Circulating CD4+CD25 high T cells in naïve Crohn's disease

Crohn's disease is considered to be caused either by an excess of T-cell effector functions and/or by a defective regulatory T-cell compartment. The aim of this study was to assess in Crohn's disease the frequency of circulating CD4(+)CD25(high) T cells that possess regulatory T-cell functions and CD4(+)CD25(low) T cells that contain activated T cells. Flow cytometry of peripheral blood was used to assess CD4(+)CD25(high) and CD4(+)CD25(low) T-cell frequencies in a cohort of 66 patients with Crohn's disease in comparison to 19 patients with ulcerative colitis and 31 healthy individuals enrolled as controls. The CD4(+)CD25(high) T-cell frequency was significantly lowered in naïve Crohn's disease (P = 0.013) and in ulcerative colitis (P = 0.001). CD4(+)CD25(low) T-cell frequency was increased in Crohn's disease (P = 0.0001) and in ulcerative colitis (P = 0.0002). Both CD4(+)CD25(high) and CD4(+)CD25(low) T-cell frequencies are altered in naïve Crohn's disease resulting in an imbalance between both populations and a relative contraction of the CD4(+)CD25(high) T-cell population.

Defective IL-10 production in severe phenotypes of Crohn's disease

Loss of tolerance toward commensal bacteria has been invoked as a mechanism for Crohn's disease. IL-10 is a key anti-inflammatory cytokine that plays a role in induction and maintenance of tolerance. The aim of this study is to determine IL-10 production in response to bacterial components in Crohn's disease patients, who were classified according to their phenotypes as stricturing, penetrating, or inflammatory. Peripheral blood was obtained from Crohn's disease patients and healthy controls. Cytokine production was measured in whole blood cultures, isolated CD4(+) cells, and monocyte-derived dendritic cells (MDDCs). Under unstimulated conditions, IL-10, but not IL-12, was down-regulated significantly in blood cultures of patients with severe phenotypes, compared with inflammatory, nonpenetrating, nonstricturing Crohn's disease patients. In response to LPS, IL-10 was up-regulated more significantly in patients with no fistulae or fibrosis. Study of IL-10 production by isolated cell subsets showed that DCs, but not CD4(+) T cells, from penetrating Crohn's disease produced significantly less IL-10 in response to LPS. Differences were not associated with the 1082A/G polymorphism in the IL-10 gene promoter. We show a defect in IL-10 production in whole blood cell cultures and MDDCs in patients with severe forms of Crohn's disease. This defect in IL-10 production by a group of Crohn's disease patients may represent a mechanism mediating more severe manifestations of the disease. We propose that treatment with IL-10 or IL-10-inducing therapies could be of particular benefit to these group of patients.

Regulatory T cells in inflammatory bowel disease

PURPOSE OF REVIEW

The intestinal immune system must orchestrate a complex balance between proinflammatory and anti-inflammatory responses to luminal antigens, and disruptions in this balance can result in inflammatory bowel disease (IBD). This review explores recent data that elucidate the role of regulatory T cells (Tregs) in the pathogenesis of IBD in mice and humans.

RECENT FINDINGS

Data from murine models of colitis implicate several novel mechanisms critical to Treg function and generation including the inhibitory cytokine interleukin-35, pericellular adenosine generation and cytokine deprivation-induced apoptosis. Although Tregs are essential in mice for the maintenance of intestinal homeostasis, their role in human IBD remains unclear. Patients with IBD appear to have relatively reduced numbers of Tregs in the blood and colon; however, Tregs from these patients are functional in vitro.

SUMMARY

Tregs are important for the maintenance of intestinal self-tolerance and will likely prove to be an important avenue for therapeutic manipulation in IBD.

Crohn's disease intestinal CD4+ T cells have impaired interleukin-10 production which is not restored by probiotic bacteria

OBJECTIVE

Crohn's disease (CD) has been associated with low mucosal interleukin (IL)-10 production, but the mechanism behind this deficiency remains unclear. The aim of this study was to investigate IL-10 and interferon (IFN)-gamma production in intestinal CD4+ T cells from CD patients and healthy volunteers (HV) and to examine how this was affected by bacterial products and the presence or absence of autologous dendritic cells.

MATERIAL AND METHODS

We cultured intestinal CD4+ T cells from CD patients (n=9) and HV (n=6) and differentiated dendritic cells from their peripheral monocytes. Intestinal T cells were stimulated with Lactobacillus strains or autologous intestinal bacteria in the presence or absence of dendritic cells. IL-10 and IFN-gamma were measured on day 4.

RESULTS

When there were autologous dendritic cells present, CD intestinal T cells produced high levels of IFN-gamma (mean 6.4 ng/ml+/-standard error of the mean 1.1 ng/ml) but low levels of IL-10 (0.7 ng/ml+/-0.1 ng/ml). In contrast, HV intestinal T cells produced less IFN-gamma (3.9 ng/ml+/-0.8 ng/ml, p=0.06) and more IL-10 (4.6 ng/ml+/-0.9 ng/ml, p=0.0001) than CD intestinal T cells. Co-culture with Lactobacilli failed to revert this imbalance in CD, but tended to do so in HV. When there were no dendritic cells, CD intestinal T cells responded to autologous bacteria with an increased IFN-gamma production (2.3+/-1.3 ng/ml) compared with HV intestinal T cells (0.3+/-0.2 ng/ml).

CONCLUSIONS

Crohn's disease intestinal CD4+ T cells display a pro-inflammatory cytokine profile with impaired production of the regulatory cytokine IL-10. Tolerogenic bacteria (Lactobacilli) failed to restore this regulatory defect.

Transient changes of transforming growth factor-β expression in the small intestine of the pig in association with weaning

It is well known that early weaning causes marked changes in intestinal structure and function, and transforming growth factor-β (TGF-β) is believed to play an important regulatory role in post-weaning adaptation of the small intestine. The present study examined the distribution and expression intensity of TGF-β in the small intestinal mucosa of pre- and post-weaning pigs using a specific immunostaining technique and Western blot analysis. The level of TGF-β in the intestinal mucosa, as estimated by Western blot analysis, did not change significantly during weaning. However, when examined by the immunostaining technique, TGF-β1 (one of the TGF-β isoforms dominantly expressed in the tissue) at the intestinal villus epithelium, particularly at the apical membrane of the epithelium, decreased significantly 4 d after weaning, while the staining intensity increased significantly at the intestinal crypts compared with that in pre-weaning pigs. These changes were transient, with the immunostaining intensity for TGF-β1 at the intestinal villi and the crypts returning to the pre-weaning level by 8 d post-weaning. The transient decrease in TGF-β1 level at the intestinal villus epithelium was associated with obvious intestinal villus atrophy and marked reduction of mucosal digestive enzyme activities. Furthermore, the number of leucocytes staining positively for TGF-β1 increased significantly in the pig intestinal lamina propria 4 d after weaning. These findings strongly suggest that TGF-β plays an important role in the post-weaning adaptation process in the intestine of the pig.

Gut microbiota: mining for therapeutic potential

The resident microbiota of the human intestine exerts a conditioning effect on intestinal homeostasis, delivering regulatory signals to the epithelium and instructing mucosal immune responses. Pattern recognition receptors are key mediators of innate host defense, and in healthy individuals, the mucosal immune system exhibits an exquisitely regulated restrained response to the resident microbiota. However, in genetically susceptible hosts, unrestrained mucosal immune activation in response to local bacterial signals can contribute to the pathogenesis of inflammatory bowel disease. Manipulation of the microbiota to enhance its beneficial components thus represents a potential therapeutic strategy for inflammatory bowel disease. Moreover, the microbiota might be a rich repository of metabolites that can be exploited for therapeutic benefit. Modern molecular techniques are facilitating improved understanding of host-microbe dialogue in health and in several disease processes, including inflammatory bowel disease. It follows that elucidating the molecular mechanisms of host-microbial interactions is now a prerequisite for a "bugs to drugs" program of discovery.

Commensal gut bacteria: mechanisms of immune modulation

Mucosal immune responses to pathogenic gut bacteria and the mechanisms that govern disease progression and outcome have been researched intensely for decades. More recently, the influence of the resident non-pathogenic or 'commensal' microflora on mucosal immune function and gut health has emerged as an area of scientific and clinical importance. Major differences occur in the mucosal immune response to pathogens and commensals. In part, this functional dichotomy is explained by the presence of virulence factors in pathogenic species, which are generally absent in commensals. Additionally, immunological 'unresponsiveness' towards the resident commensal microflora is thought to permit their successful colonisation and co-existence within the host gut. However, evidence of an active dialogue between members of the commensal microflora and the host mucosal immune system is rapidly unfolding. This crosstalk is likely to affect immunological tolerance and homeostasis within the gut and to explain some of the differential host responses to commensal and pathogenic bacteria.

Activated marrow-infiltrating lymphocytes effectively target plasma cells and their clonogenic precursors

A major limitation of adoptive immunotherapy is the availability of T cells specific for both terminally differentiated tumor cells and their clonogenic precursors. We show here that marrow-infiltrating lymphocytes (MILs) recognize myeloma cells after activation with anti-CD3/CD28 beads with higher frequency than activated peripheral blood lymphocytes from the same patients. Furthermore, activated MILs target both the terminally differentiated CD138+ plasma cells and the myeloma precursor as shown by profound inhibition in a tumor clonogenic assay. The presence of antigen in the marrow microenvironment seems to be important for the maintenance of tumor specificity. Taken together, these results highlight the intrinsic tumor specificity of MILs and describe a novel approach for the generation of tumor-specific T-cell populations suitable for adoptive immunotherapy of multiple myeloma.

Preventive and therapeutic effects of NF-kappaB inhibitor curcumin in rats colitis induced by trinitrobenzene sulfonic acid

AIM: To ascertain the molecule mechanism of nuclear factor-κB (NF-κB) inhibitor curcumin preventive and therapeutic effects in rats’ colitis induced by trinitrobenzene sulfonic acid (TNBS).

METHODS: Sixty rats with TNBS-induced colitis were treated with 2.0% curcumin in the diet. Thirty positive control rats were treated with 0.5% sulfasalazine (SASP). Thirty negative control rats and thirty model rats were treated with general diet. Changes of body weight together with histological scores were evaluated. Survival rates were also evaluated. Cell nuclear NF-κB activity in colonic mucosa was evaluated by using electrophoretic mobility shift assay. Cytoplasmic IκB protein in colonic mucosa was detected by using Western Blot analysis. Cytokine messenger expression in colonic tissue was assessed by using semiquantitative reverse-transcription polymerase chain reaction.

RESULTS: Treatment with curcumin could prevent and treat both wasting and histopathologic signs of rats with TNBS-induced intestinal inflammation. In accordance with these findings, NF-κB activation in colonic mucosa was suppressed in the curcumin-treated groups. Degradations of cytoplasmic IκB protein in colonic mucosa were blocked by curcumin treatment. Proinflammatory cytokine messenger RNA expression in colonic mucosa was also suppressed.

CONCLUSION: This study shows that NF-κB inhibitor curcumin could prevent and improve experimental colitis in murine model with inflammatory bowel disease (IBD). The findings suggest that NF-κB inhibitor curcumin could be a potential target for the patients with IBD.

Indium-labelled human gut-derived T cells from healthy subjects with strong in vitro adhesion to MAdCAM-1 show no detectable homing to the gut in vivo

Integrin alpha4beta 7 is the principal gut-homing receptor, and it is assumed that expression of this specific integrin directs lymphocytes to the gut in vivo. Adoptive cellular immunotherapy against inflammatory bowel disease (IBD) may depend on the expression of integrin alpha4beta 7 to accomplish local delivery of intravenously injected regulatory T cells in inflamed gut mucosa. The present study aimed to investigate whether in vitro expanded human T cells from the colonic mucosa maintain integrin expression, show in vitro adhesion and retain in vivo gut-homing properties during cultivation. Whole colonic biopsies from healthy subjects were cultured in the presence of interleukin-2 (IL-2) and IL-4. The integrin expression of the cultured T cells was determined by flow cytometry and in vitro adhesion was assessed in a mucosal addressin cell adhesion molecule 1 (MAdCAM-1) adhesion assay. We studied the homing pattern after autologous infusion of 3 x 10(8 111)Indium ((111)In)-labelled T cells in five healthy subjects using scintigraphic imaging. The cultured CD4(+)CD45RO(+) gut-derived T cells express higher levels of integrin alpha4beta 7 than peripheral blood lymphocytes (PBLs) and show strong adhesion to MAdCAM-1 in vitro, even after (111)In-labelling. Scintigraphic imaging, however, showed no gut-homing in vivo. After prolonged transit through the lungs, the T cells migrated preferentially to the spleen, liver and bone marrow. In conclusion, it is feasible to infuse autologous T cells cultured from the gut mucosa, which may be of interest in adoptive immunotherapy. Despite high expression of the gut-homing integrin alpha4beta 7 and adhesion to MAdCAM-1 in vitro, evaluation by (111)In-scintigraphy demonstrated no gut-homing in healthy individuals.