Immune events associated with inflammatory bowel disease

Intestinal inflammation in TNBS sensitized rats as a model of chronic inflammatory bowel disease

An enteritis, based on a delayed-type hypersensitivity reaction, was induced in TNBS (2,4,4-trinitrobenzenesulphonic acid) sensitized rats by multiple intrajejunal challenge with TNBS via an implanted catheter. This treatment induced chronic inflammation of the distal small intestine characterized by intense hyperaemia, oedema and gut wall thickening as assessed by macroscopic scoring and weighing a defined part of the dissected intestine. Histologically, the inflammatory response included mucosal and submucosal cell infiltration by lymphocytes and histiocytes, transmural granulomatous inflammation with multinucleated cells and activated mesenteric lymph nodes. Ex vivo stimulated release of the inflammatory mediator LTB₄ in the dissected part of the intestine was increased following TNBS treatment. Drug treatment with sulphasalazine or 5-aminosalicylic acid improved the enteritis score and attenuated TNBS induced oedema formation and LTB₄ production. The applicability and relevance of this new model are discussed with respect to drug development and basic research of inflammatory bowel diseases.

Combination therapy using fexofenadine, disodium cromoglycate, and a hypoallergenic amino acid-based formula induced remission in a patient with steroid-dependent, chronically active ulcerative colitis

Corticosteroids and 5-aminosalicylic acid are the primary standard therapy for inflammatory bowel disease. Recent immunologic data implicate an involvement of mast cell activation followed by increased histamine secretion and elevated tissue concentrations of histamine in the pathogenesis of ulcerative colitis. In the present case, the clinical course of a 35-year-old man with steroid-dependent chronic active ulcerative colitis, who did not respond to high-dose steroids, antibiotics, or azathioprine during 3 years, is reported. Clinical disease activity and established serological markers were recorded during 6 weeks of unsuccessful therapy and during the next 6 weeks, as a new nonsedative antihistaminergic drug, a mast cell stabilizer, and an hypoallergenic diet were implemented in addition to conventional therapy. Induction of remission was achieved within 2 weeks after treatment with fexofenadine, disodium cromoglycate, and an amino acid-based formula. Clinical disease activity, stool frequency, leukocytes, c-reactive protein, and orosomucoid levels in serum decreased rapidly. Daily steroid administration could be gradually reduced along with 6 weeks of this treatment. This report suggests that histamine and mast cell activity may be important pathophysiological factors responsible for persistent clinical and mucosal inflammatory activity in ulcerative colitis despite the use of steroids. In ulcerative colitis, patients unresponsive to conventional treatment, therapeutic considerations should also include an antiallergic approach when further signs of atopy or intestinal hypersensitivity are present.

CCR4 is an up-regulated chemokine receptor of peripheral blood memory CD4+ T cells in Crohn's disease

Several chemokine receptors are expressed selectively on the surface of T cells depending on their polarization. The aim of this study was to characterize chemokine receptor expression in peripheral blood memory T cells in Crohn's disease (CD) and ulcerative colitis (UC), and to correlate the expression with disease activity. Peripheral blood mononuclear cells (PBMCs) were obtained from 24 patients with CD, 30 patients with UC, 24 normal controls and 10 disease controls. PBMCs were stained by anti-CCR3, CCR4, CCR5, CXCR3, CD4, CD8, CD45RO and beta 7 integrin, and the expression of the chemokine receptors were determined by flow cytometry. CCR4 expression on memory T cells was significantly lower in UC than in CD or normal controls, and that of memory CD4+ T and beta 7(high) memory CD4+ T cells was significantly higher in CD than in UC or normal controls. CCR4 expression on memory CD4+ T cells exhibited significant positive correlation with disease activity in CD, and this decreased significantly after treatment. Such a decrease was not found in the disease controls. CCR5 and CXCR3 expression on memory CD8+ T cells was significantly lower in CD than in normal controls. CXCR3 expression on beta 7(high) memory CD4+ T and CXCR3 expression on memory CD8+ T cells were lower in UC than in normal controls. These findings suggest that in peripheral blood memory T cells, chemokine receptor expression is different between CD and UC. Enhancement of CCR4 and suppression of CCR5 and CXCR3 seem to be the characteristic chemokine receptor profile in peripheral blood memory T cells of CD.

CD4+ cell oligoclonality in Crohn's disease: evidence for an antigen-specific response

To identify disease-specific T cell changes that occur in Crohn's disease (CD) the T-cell receptor (TCR) BV repertoires of lamina propria lymphocytes (LPL) from both disease-active and disease-inactive colonic tissue of three CD patients were compared by a quantitative polymerase chain reaction (qPCR) and CDR3 length analysis. It was observed that the BV repertoires of LPL isolated from the disease-active and disease-inactive parts of the colon of the same individual were different, and most of the differences occurred in CD4+ LPL with very few differences in the CD8+ populations of LPL. Although the pattern of BV segments that was increased in disease-active relative to disease-inactive tissue was different for all three CD patients, there was an increase in the levels of BV11, 13S2, 15, 16, and 17 segments in the disease-active tissue of all three patients. Standard CDR3 length analysis of BV11, 13S2, 15, 16, and 17 segments revealed that in two of the three CD patients there was a striking degree of TCR oligoclonality in the disease-active tissue that was absent from disease-inactive tissue of the same individual. Additional differences between the disease-active and disease-inactive tissues were observed using a more refined method of CDR3 length analysis, which employs BV- and BJ-specific primers. These observations suggest that at least some of the inflammation in CD is the result of responses by CD4+ T cells to specific antigens.

Crohn's disease is accompanied by changes in the CD4+, but not CD8+, T cell receptor BV repertoire of lamina propria lymphocytes

To identify disease-specific T cell changes that occur in Crohn's disease (CD), the T cell receptor (TCR) BV repertoires of lamina propria lymphocytes (LPL) isolated from the diseased colon of seven CD patients and eight controls were determined by semiquantitative polymerase chain reaction (qPCR). As an internal control for the effects of HLA and other genes on the TCR repertoire, the BV repertoires of peripheral blood lymphocytes (PBL) from the same individuals were similarly determined and used for comparison. It was observed that the BV repertoires of LPL and PBL within the same individual were very different in both the CD and control groups. However, the CD4+, but not CD8+, repertoires of LPL and PBL differed to a much greater extent in the CD group than in the control group. Furthermore, in each CD patient there was a unique pattern of BV segments which were increased in the CD4+ LPL repertoire relative to that in PBL. These observations suggest that the inflammatory process in CD involves responses by specific CD4+ T cells to specific antigens. The isolation of such inflammation-specific CD4+ T cells may make it possible to identify the antigens which are responsible for the inflammatory process in CD and provide a better understanding of its pathogenesis.

Evidence that CD4+, but not CD8+ T cells are responsible for murine interleukin-2-deficient colitis

Mice deficient in interleukin-2 production (IL-2null mice) develop colonic inflammation closely resembling ulcerative colitis in humans. Although this disease is marked by substantial infiltration of the colon by CD8+ and CD4+ T lymphocytes, no function has yet been assigned to these T cell subsets in the development of colitis in the IL-2null mouse. For the present study, we investigated the involvement of T lymphocytes in the onset of colitis in IL-2null mice, and examined the possible role played by cytotoxic T cells. Both lamina propria lymphocytes (LPL) and intraepithelial lymphocytes (IEL) of the colon of IL-2null mice were potently cytotoxic ex vivo in short-term redirected cytotoxic lymphocyte (CTL) assays. In contrast, colonic T cells of wild-type animals showed little or no constitutive cytotoxic T cell activity. Colonic CTL were detectable prior to the appearance of disease in IL-2null animals and CTL activity was confined to the TcR alpha beta, rather than to the TcR gamma delta IEL subset. IL-2null animals crossed with major histocompatibility complex class I-deficient mice [IL-2null x beta 2 microglobulin (beta 2mnull) mice] also developed colitis, which appeared even earlier than in most IL-2null mice. These findings suggest that neither CD8+ IEL nor LPL were causal in the onset of colitis in IL-2null animals. In IL-2null x beta 2mnull mice, an ulcerative colitis-like disease was evident from histological studies and immunohistological staining which showed very large numbers of CD4+ lymphocytes within the intestinal mucosa. Significant ex vivo killing by CD4+ T cells was observed in IL-2null x beta 2null animals, although this required an extended incubation time compared to colonic CD8+ T cells. Peripheral as well as colonic CD4+ T cells in IL-2null and IL-2null x beta 2mnull animals, were activated as judged by their cell surface phenotype (CD45RBlo, L-selectinlo and CD69+). In light of these findings, we propose that infiltrating CD4+, but not CD8+ T cells are central to the inflammation observed in the intestinal mucosa in IL-2null colitis.

Intraepithelial and lamina propria leucocyte subsets in inflammatory bowel disease: an immunohistochemical study of colon and rectal biopsy specimens

AIMS

To gain new insights into the pathogenesis and differential diagnosis of ulcerative colitis and colonic Crohn's disease.

METHODS

Immunohistochemistry for different leucocyte subsets was performed in biopsy specimens of the sigmoid colon and rectum from 55 patients with inflammatory bowel disease and 11 healthy controls.

RESULTS

Colonic biopsy specimens from patients with active ulcerative colitis had significantly higher numbers of CD45+ and CD3+ leucocytes compared with those from patients with inactive disease, and higher numbers of total leucocytes and macrophages than those from patients with Crohn's disease. Rectal biopsy specimens from patients with Crohn's disease had greater numbers of intraepithelial leucocytes (CD45, CD3 and CD8 cells) than specimens from patients with active or inactive ulcerative colitis, or from healthy controls.

CONCLUSIONS

Because of the phenotypic differences in the inflammatory infiltrate in the mucosa from the sigmoid colon and the rectum, the segment of the intestine to be biopsied should be specified. Assessment of the leucocytic component of the intraepithelial infiltrate in rectal biopsy specimens was more useful than examination of colonic biopsy specimens in the differential diagnosis of ulcerative colitis and Crohn's disease.

Increase of circulating gamma/delta T lymphocytes in the peripheral blood of patients affected by active inflammatory bowel disease

In order to study the role of gamma/delta T cells in the pathogenesis of inflammatory bowel disease (IBD) in humans, we measured the percentage of these cells in the peripheral blood, assessed the ratio of the non-disulphide-linked (delta TCS1) type of T cell receptor (TCR) in the total gamma/delta T cells, studied the co-expression of gamma/delta TCR and accessory molecules CD8 and CD16, and compared these data with both the type and the activity of the disease. Percentage levels and absolute numbers of gamma/delta+ T cells were higher in active patients than in controls (P < 0.05), mainly as a result of an increase of V delta 1+ (delta TCS1) T cell subset (P < 0.05). This trend was strongly retained independently of disease activity and clinical picture. An increased percentage of TCR delta 1+/CD16+ cells was observed in our patients compared with controls (P < 0.05). In contrast, no difference was observed as far as the TCR delta 1+/CD8+ cells were concerned. These results suggest that IBD is associated with an expansion of gamma/delta T cells in peripheral blood, which may play a role in the pathogenesis of these disorders.

T cell cytotoxicity of autologous and allogeneic lymphocytes in a patient with Crohn's disease

We report a 27-year-old male with Crohn's disease (CD) of the small and large intestine, whose peripheral blood lymphocytes (PBL) showed increased cell-mediated cytotoxicity (CTL). Autologous and allogeneic effector cells from PBL and intestinal lymph nodes (LN) were isolated on a Ficoll-Hypaque gradient. Colonic cells were prepared as the target and were incubated for 6h with effector cells, after being labeled with Na(2)51CrO4. The CTL activity [effector/target (E/T) ratio, 100:1] of PBL for autologous targets was increased by 38% compared with that in normal subjects (< 10%), while that shown by LN was not increased (14%). The CTL activity of allogeneic PBL prepared from three of four other CD patients was also increased. Anti-major histocompatibility (MHC) class I and II and CD4 and CD8 monoclonal antibodies (50 micrograms/ml) significantly inhibited CTL activity. Complement-mediated depletion of CD2+ cells significantly reduced CTL activity. These results suggest that MHC-restricted CTL may play a role in mucosal damage in some patients with Crohn's disease.

Evidence for an altered T-cell receptor repertoire in Crohn's disease

We have compared the frequencies of T cells expressing each of four different T cell receptor (TCR) V beta segments in lamina propria and peripheral blood lymphocytes of 12 Crohn's disease (CD), six ulcerative colitis (UC), and 10 control patients in an attempt to identify disease-specific changes. The frequencies of CD4+ and CD8+ cells reacting with each of four fluoresceinated TCR-specific monoclonal antibodies directed against V beta 5, V beta 6.7a, V beta 8, and V beta 12 were determined by flow cytometry. There was no difference among the groups in the average frequency of any single V beta segment in either the CD4+ or CD8+ subpopulations. However, when the sum of the differences in V beta frequencies (delta score) between peripheral blood lymphocytes (PBL) and lamina propria lymphocytes (LPL) were determined for each individual, significant differences were observed between the CD4+ and CD8+ populations and among the patient groups. In all three patient groups, there were significant individual differences between LPL and PBL in the frequencies of CD8+ and CD4+ cells reacting with the four V beta-specific mAb. In Controls and UC, this difference was, on average, two-fold greater in CD8+ cells than in CD4+. In CD, however, this difference was, on average, the same for CD8+ and CD4+ cells. These observations suggest that (1) the human colonic LPL TCR repertoire is normally different from that of PBL, especially in the CD8+ population and (2) there is an alteration in the LPL TCR repertoire in CD which is not observed in Controls or UC.

Effect of methylprednisolone on small bowel, spleen and liver changes in a murine model of inflammatory bowel disease

The aim of this study was to evaluate the influence of methylprednisolone (1 mg/kg, i.p.) on inflammatory lesions in the small bowel, liver (pericholangitis) and spleen (lymphofollicular proliferation), in a model of inflammatory bowel disease induced by 2.4-dinitrofluorobenzene in previously sensitized BALB-c mice. As a parameter of corticosteroid anti-inflammatory and immunosuppressive action, we simultaneously investigated its effects on mononuclear cell accumulation within the ileal lamina propria and submucosa during the observed time period (1-30 days). We noted a significant decrease in accumulation of mononuclear cells within the lamina propria (P < 0.001). An effect on mononuclear cell infiltration within the ileal submucosa was also noted but was not statistically significant. In addition, pericholangitis in the liver and lymphofollicular proliferation in the spleen were not observed in the experimental group during treatment with methylprednisolone. The results of this study indicate that the previously described model of intestinal inflammation could be used in further research of present and new therapeutic modalities for inflammatory bowel disease.

A model of inflammatory bowel disease induced by 2,4-dinitrofluorobenzene in previously sensitized BALB-c mice

The aim of this study was to develop a model of inflammatory bowel disease (IBD) induced by colonic application of 2,4-dinitrofluorobenzene in previously sensitized BALB-c mice. During the follow-up period of 30 days we observed ulcerations, haemorrhage, necrosis, and mononuclear infiltration in the colonic mucosa of previously sensitized (experimental) and, to a lesser extent, nonsensitized (control) animals. In addition, the animals in the experimental group developed adhesions, thickening of colonic segments, stenosis, and dilatation of the colon, and some animals also developed megacolon. Oedema, mononuclear infiltration, and superficial ulcerations were observed in the ileum of experimental animals and, to a lesser extent, in the control group. In addition, the animals in the experimental group developed extraintestinal changes in the liver and spleen (that is, pericholangitis and lymphofollicular proliferation). We suggest that this model of IBD may have some value for the study of early pathogenetic mechanisms of IBD and for developing new therapeutic modalities for this condition.

Reactive oxygen metabolites and colitis: a disturbed balance between damage and protection. A selective review

Enhanced local production of reactive oxygen metabolites has been found in association with colitis, both experimentally and in humans. Cellular and biochemical systems involved have been identified, and 5-aminosalicylic acid-containing drugs but, more effectively, specific scavengers have been found to reduce the intestinal inflammatory process. The multitude of reactions in which oxygen metabolites participate provides a new area of research in intestinal inflammation. These basic studies might bring related clinical studies in an era of new anti-inflammatory drugs for inflammatory bowel disease specifically designed to scavenge toxic oxygen metabolites.