Deficient interleukin 2 dependent proliferation pathway in T lymphocytes from active and inactive ulcerative colitis patients

Role of serum cytokine profile in ulcerative colitis assessment

BACKGROUND

Several cytokines are overexpressed in the colonic mucosa of patients with ulcerative colitis (UC). The measurement of these parameters in plasma could be useful in diagnosis and disease assessment.

METHODS

In all, 67 UC patients and 21 healthy controls were enrolled. At inclusion, clinical, endoscopic, and histological disease activity were assessed using the Ulcerative Colitis Activity Index (UCAI) and the Baron and Geboes scales, respectively. Serum cytokine concentrations were analyzed with a multiplex system (Bio-Plex pro, Bio-Rad) measuring interleukin (IL)-1-β, IL-2, IL-6, IL-8, IL-10, IL-13, IL-17, interferon-gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α). Multiple logistic regression was used to design a serum cytokines profile.

RESULTS

In the UC group the disease activity was moderate to severe based on clinical evaluation in 35 patients (52.2%), by endoscopic appearance in 45 (67.2%), and in 53 patients (81.6%) using histology. With respect to controls, the multivariate analysis identified that UC patients had higher IL-8 (odds ratio [OR] = 1.37; P = 0.002) and IL-10 concentrations (OR = 3.88; P = 0.012) with lower levels of IFN-γ (OR = 0.95; P = 0.002). The model had an accuracy of 77.3%, which increased to 94.6% when only newly diagnosed patients were considered. Patients with moderate to severe disease according to their clinical score showed a higher concentration of IL-8 (OR = 1.16; P = 0.012) and IL-10 (OR = 1.76; P = 0.039) with lower levels of IL-17 (OR = 0.97; P = 0.021). The IL-8 serum concentration was also related to endoscopic and histological severity (OR = 1.10; P = 0.026 and OR = 1.33, P = 0.017, respectively).

CONCLUSIONS

A serum cytokine profile may be an auxiliary tool for the diagnosis and severity assessment of UC. IL-8 seems to be a reliable biomarker, closely related to disease activity.

Cytokines in inflammatory bowel disease

Over the past decade, much has been learned regarding the role of various cytokines in the pathogenesis of inflammatory bowel disease. Several cytokine ‘knockout’ models in mice have been shown to develop colitis, while alterations in the production of various cytokines has been documented in human Crohn's disease and ulcerative colitis. In recent years, attempts have been made to treat these diseases through modulation of cytokine production or action. This review focuses on the cytokines that have been implicated in the pathogenesis of inflammatory bowel disease. The evidence for and against a role for particular cytokines in intestinal inflammation is reviewed, as is the experimental and clinical data suggesting that cytokines are rational targets for the development of new therapies.

The Vitamin D analogue TX 527 blocks NF-kappaB activation in peripheral blood mononuclear cells of patients with Crohn's disease

Crohn's disease (CD) is an inflammatory disease characterized by the activation of the immune system in the gut. Since tumor necrosis factor (TNF-alpha) plays an important role in the initiation and perpetuation of intestinal inflammation in CD, we investigated whether TX 527 [19-nor-14,20-bisepi-23-yne-1,25(OH)(2)D(3)], a Vitamin D analogue, could affect peripheral blood mononuclear cells (PBMC) proliferation and exert an immunosuppressive effect on TNF-alpha production in CD patients, and whether this immunosuppressive action could be mediated by NF-kappaB down-regulation. TX 527 significantly decreased cell proliferation and TNF-alpha levels. On activation, NF-kappaB, rapidly released from its cytoplasmatic inhibitor (IKB-alpha), transmigrates into the nucleus and binds to DNA response elements in gene promoter regions. The activation of NF-kappaB, stimulated by TNF-alpha, and its nuclear translocation together with the degradation of IKB-alpha were blocked by TX 527. At the same time, NF-kappaB protein levels present in cytoplasmic extracts decreased in the presence of TNF-alpha and increased when PBMC were incubated with TX 527. The results of our studies indicate that TX 527 inhibits TNF-alpha mediated effects on PBMC and the activation of NF-kappaB and that its action is mediated by Vitamin D receptor (VDR), which is activated when the cells are stimulated with TX 527.

Biochemical effects of KH 1060 and anti-TNF monoclonal antibody on human peripheral blood mononuclear cells

The aim of this study was to investigate whether the vitamin D analogue KH 1060 could exert a suppressive action on Tumor necrosis factor-alpha (TNF-alpha). The chimeric anti-TNF-alpha monoclonal antibody (anti-TNF), alone or in combination with KH 1060, was also used. KH 1060 (0.01, 0.1, 1 nM) significantly inhibited cell proliferation, determined after 5 days by [3H]thymidine incorporation, when peripheral blood mononuclear cells (PBMC), obtained from healthy subjects, were stimulated with phytohaemagglutinin (PHA) and incubated for 24 h in the absence and in the presence of lipopolysaccharide (LPS). In the same experimental conditions, anti-TNF exerted a significant inhibition on PBMC proliferation, at the lowest doses (0.001, 0.01 microg/ml) in the absence of LPS, and at 0.001, 1, 10 microg/ml in its presence. A synergistic inhibition was registered combining KH 1060 and anti-TNF, at well-defined concentrations. 0.1 nM KH 1060 produced a significant decrease in TNF-alpha levels, determined by ELISA, although less remarkable than in the presence of anti-TNF. This decrease was synergistic, associating 0.1 nM KH 1060 and 0.1 microg/ml anti-TNF. VDR protein levels were increased by 0.1 nM KH 1060, 0.1 microg/ml anti-TNF or their combination. The protein levels of two oncogenes, Bax and Bcl-2, remained unchanged, when PBMC were incubated with KH 1060, anti-TNF or their combination in the absence of LPS, while, in its presence, an increase was registered. The demonstrated anti-TNF-alpha effect of KH 1060 may suggest for this compound an immunosuppressive action and the possibility to synergistically act with other drugs.

Effect of anti-TNF therapy and vitamin D derivatives on the proliferation of peripheral blood mononuclear cells in Crohn's disease

Infliximab treatment demonstrated clinical and endoscopic benefits in active refractory and fistulizing Crohn's disease. The aim of this research was to investigate the proliferative response of peripheral blood mononuclear cells (PBMC) obtained from patients with active and fistulizing Crohn's disease treated with infliximab therapy. PBMC proliferation and VDR protein levels were also studied when 1,25(OH)2D3 or its analogues (EB 1089, KH 1060) were added to cells cultures. At day 5 of culture, the proliferation of PBMC obtained from patients responsive to the therapy showed a remarkable decrease (about 60%) at T6 (after two infusions) with respect to T0 (before the first infusion). On the contrary, in the unresponsive patient, the proliferative response was four times higher at T6 in comparison with T0. Vitamin D derivatives induced a decrease in cell proliferation higher in responsive patients than in the unresponsive one. Increased VDR levels during therapy were registered only in the unresponsive patient. Our results indicate that PBMC proliferation and VDR expression may be useful indicators to predict the response of patients with Crohn's disease to the infliximab therapy.

Changes of CD8+CD28- T regulatory cells in rat model of colitis induced by 2,4-dinitrofluorobenzene

AIM: To determine the changes of CD8+ T subsets especially CD8+CD28- T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB).

METHODS: The rat model of experimental colitis was induced by enema with DNFB. Ten days later, colonic intraepithelial and splenic lymphocytes were isolated from colitis animals (n = 16) and controls (n = 8). The proportion of CD8+ T cells, CD8+CD28+ T cells and CD8+CD28- T regulatory cells were determined by flow cytometry.

RESULTS: The model of experimental colitis was successfully established by DNFB that was demonstrated by bloody diarrhea, weight loss and colonic histopathology. The proportion of CD8+ T cells in either splenic or colonic intraepithelial lymphocytes was not significantly different between colitis animals and controls (spleen: 34.6% ± 7.24% vs 33.5% ± 9.41%, colon: 14.0% ± 8.93% vs 18.0% ± 4.06%, P > 0.05). But CD8+CD28- T regulatory cells from colitis animals were significantly more than those from controls (spleen: 11.3% ± 2.26% vs 5.64% ± 1.01%, colon: 6.50% ± 5.37% vs 1.07% ± 0.65%, P < 0.05). In contrast, CD8+CD28+ T cells from colitis animals were less than those from controls (spleen: 23.3% ± 6.14% vs 27.8% ± 9.70%, P = 0.06; colon: 7.52% ± 4.18% vs 16.9% ± 4.07%, P < 0.05). The proportion of CD8+CD28- T regulatory cells in splenic and colon intraepithelial CD8+ T cells from colitis animals was higher than that from controls (spleen: 33.3% ± 5.49% vs 18.4% ± 7.26%, colon: 46.0% ± 14.3% vs 6.10% ± 3.72%, P < 0.005).

CONCLUSION: Experimental colitis of rats can be induced by DNFB with simplicity and good reproducibility. The proportion of CD8+CD28- T regulatory cells in rats with experimental colitis is increased, which may be associated with the pathogenesis of colitis.

Alteration of intestinal intraepithelial lymphocytes after massive small bowel resection

BACKGROUND

Intraepithelial lymphocytes (IEL) comprise the inner most layer of the gut immune system, and play a critical role in protecting the host from enteric organisms. Massive small bowel resection (MSBR) is one such clinical condition where patients are at particularly high risk for the development of such enteric infectious complications. Because of this, we hypothesized that the IEL may change significantly after the formation of a MSBR. To address this, a mouse model of MSBR was created and the acute phenotypic and functional characteristics of the IEL were studied.

MATERIALS AND METHODS

Mice underwent a 70% mid-small bowel resection. After 7 days, IEL were isolated and analyzed for phenotypic changes by flow cytometry. IEL cytokine expression was performed with semiquantitative polymerase chain reaction techniques. To assess the functional significance of these changes, IEL proliferative response was assessed in vitro.Results. MSBR led to significant decreases in specific IEL subpopulations: CD 44+ (used as a marker of cell maturity); CD 8alphabeta+ (marker of thymic derivation), and CD 69+ (marker of T cell activation). Compared with controls, IEL TNF-alpha mRNA expression increased 84%, while IL-2 and IL-10 mRNA expression decreased by 69 and 72%, respectively. Spontaneous proliferation of IEL in the MSBR group was significantly higher than controls, however, proliferation failed to increase with T cell stimulation.Conclusion. These changes suggest a shift to a more immature and possibly less activated cell population. It is possible that such alterations may play an important role in the increase in enterically derived infections in patients with MSBR.

Synergistic inhibitory effect of cyclosporin A and vitamin D derivatives on T-lymphocyte proliferation in active ulcerative colitis

OBJECTIVE

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the hormonal active form of vitamin D3, could represent a potentially therapeutic agent in autoimmune diseases. Cyclosporin A (CsA) shows immunoregulatory properties, which, in many respects, seem to be similar to those of 1,25(OH)2D3. Our aim was to investigate the possible synergistic effect exerted by CsA in combination with 1,25(OH)2D3 or its nonhypercalcemic analogues, EB 1089 and KH 1060, on the proliferative response of T lymphocytes obtained from active ulcerative colitis patients.

METHODS

The T lymphocyte-enriched population was treated with phytohemagglutinin and CsA (doses from 1 ng to 1000 ng/ml) alone or in association with 1,25(OH)2D3 or EB 1089 or KH 1060 (0.1, 1, 10 nM final concentration). Cell proliferation was determined by [3H]thymidine incorporation and analyzed on day 5 of culture.

RESULTS

After incubation with CsA, T lymphocyte proliferation was significantly inhibited in comparison with the vehicle-treated cultures. However, T lymphocytes from ulcerative colitis patients were significantly more sensitive to CsA than those from healthy controls. The inhibition in T lymphocyte proliferation, after treatment of the cultures with CsA associated with either 1,25(OH)2D3 or EB 1089 or KH 1060, was synergistic at well-defined concentrations.

CONCLUSIONS

Taking into account the lowest CsA dose (1 ng/ml), the highest synergistic inhibition in the proliferation of T lymphocytes prepared from ulcerative colitis patients was found combining CsA and 10 nM of 1,25(OH)2D3 or 10 nM of EB 1089 or KH 1060 at the three concentrations. The results obtained, associating the lowest CsA dose and the lowest KH 1060 concentration, may suggest an alternative therapeutic approach in these patients, reducing the dose, and consequently the toxicity, of CsA.

Serum angiotensin I-converting enzyme is reduced in Crohn's disease and ulcerative colitis irrespective of genotype

OBJECTIVES

Crohn's disease (CD) is recognized to be a vascular endothelial-associated disease. Angiotensin I-converting enzyme (ACE) exists mainly in endothelial cells. There are some reports on serum ACE levels in patients with CD, but the ACE level is still controversial. Recently, genetic control of serum ACE levels by ACE gene polymorphisms (classified as II, ID, and DD) has been suggested. Although we must consider such polymorphisms to elucidate ACE levels in patients with CD, there is no report about this.

METHODS

We studied 341 healthy controls (male/female = 178/162), 39 patients with CD (31/8), 43 patients with ulcerative colitis (UC) (22/21) and 19 patients with infectious enterocolitis (8/11). The polymorphism in intron 16 of the ACE gene was examined by PCR. Serum ACE levels were measured by the method of Kasahara.

RESULTS

Serum ACE levels in patients with CD and UC were significantly lower than in healthy controls, irrespective of the genotype of ACE (genotype II: CD 7.0+/-2.5 [mean +/- SD], UC 7.1+/-3.3, controls 11.8+/-2.9, genotype ID: CD 9.7+/-4.1, UC 11.4+/-4.6, controls 15.2+/-3.6, genotype DD: CD 13.9+/-5.8, UC 10.7+/-3.6, controls 19.3+/-3.9 IU/L, controls vs CD, UC; p < 0.01, 0.05). However, there was no significant difference in serum ACE levels between CD and UC.

CONCLUSIONS

Considering ACE gene polymorphism, serum ACE levels in patients with inflammatory bowel disease are lower than in controls. Serum ACE levels reflect a part of the pathogenesis of inflammatory bowel disease.

Suppressive effect of 1,25-dihydroxyvitamin D3 and its analogues EB 1089 and KH 1060 on T lymphocyte proliferation in active ulcerative colitis

This study examined the effect exerted by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and two vitamin D analogues, EB 1089 and KH 1060, on the proliferation of T lymphocytes obtained from ulcerative colitis (UC) patients and healthy controls. The proliferative response of T lymphocytes to phytohaemagglutinin treatment was first analyzed on days three, five, and seven of culture. Cell proliferation was significantly lower in UC patients than that observed in healthy controls. The highest proliferation value, in either controls or patients, was registered on day five of culture. On day seven, a decrease in proliferation occurred, less evident in patients with respect to controls, whereas on day three, controls and patients showed the same proliferation value. The response of T lymphocytes of either healthy controls or UC patients to 1,25(OH)2D3, EB 1089, or KH 1060 was then investigated, treating the cells for three, five, and seven days with 10 nM vitamin D derivatives. In the presence of these compounds, cell proliferation was significantly inhibited in both groups, but on day seven, the inhibition of lymphocyte proliferation was remarkable in controls, whereas in patients it was similar to that registered on day five. The highest inhibition values were always obtained in the presence of KH 1060, and the time dependence was continuous in controls, but in the presence of EB 1089 only in patients. T lymphocytes prepared from healthy controls and UC patients were then cultured for five days in the presence of vitamin D derivatives at three different concentrations (0.1, 1, and 10 nM). In the two groups, a dose-dependent inhibition was registered in the presence of 1,25(OH)2D3 or EB 1089, while the inhibition of proliferation exerted by KH 1060 was not dose-dependent. The results obtained suggest an option for the use of the two non-hypercalcemic vitamin D analogues in the therapy of UC patients, perhaps in association with other immunosuppressive drugs.

Fas/Fas ligand expression and characteristics of primed CD45RO+ T cells in the inflamed mucosa of ulcerative colitis

BACKGROUND

Chronic immune activation in the colon is characteristic of ulcerative colitis (UC). Fas/Fas ligand (FasL) system is a mechanism responsible for activation-induced cell death (AICD), which maintains homeostasis within the immune system. Thus, Fas/FasL expression on activated colonic T cells of UC patients, as well as the susceptibility of such T cells to AICD was investigated in order to determine the role of activated colonic T cells in the long lasting inflammation in UC.

METHODS

Fas, FasL, and CD45RO expression on peripheral blood and colonic T cells of UC patients were assayed by flow cytometry. Apoptosis of colonic T cells induced by anti Fas antibody was assessed using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay.

RESULTS

The majority of colonic T cells expressed both CD45RO and Fas in the colonic mucosa, a situation that was quite different from that in the peripheral blood. The number of CD45RO+CD8+ and Fas+CD8+ T cells was significantly lower in UC patients than the controls, unlike the number of Fas+CD4+ T cells. In contrast, the number of both CD45RO+CD4+ and CD45RO+CD8+ T cells in UC mucosa expressing FasL was significantly higher than in the controls. While Fas mediated apoptosis of CD45RO+CD8+ T cells was higher in UC patients than the controls, the number of apoptotic CD45RO+CD4+ T cells from UC mucosa was not.

CONCLUSIONS

In UC patients, CD45RO+CD4+ T cells are less sensitive to apoptotic signals mediated by Fas. These phenomena may contribute to the pathogenesis of UC.

Impaired mitogenic response of peripheral blood T cells in ulcerative colitis is not due to apoptosis

An abnormal immune response may play a pathogenic role in ulcerative colitis (UC). Animal models suggest that T-cell regulation may be of central importance in the inflammatory process. Our aims were the characterization of the phenotype and functional status of circulating T-cells in ulcerative colitis patients and to determine if activation-induced cell death in CD4 and CD8 lymphocytes in patients differs from healthy controls. Forty-eight patients (24 women and 24 men) fulfilling the histopathological, clinical, and immunological criteria for UC were studied. T-cell phenotype and function were studied in blood lymphocytes from patients with ulcerative colitis and healthy donors by flow cytometric analysis, as well as [3H]thymidine incorporation. There were no significant differences in the percentage of T-cell subpopulations (CD3, CD4, CD8) and NK cells in the different groups. The percentage of cells in growth phase S+G2M at two and three days of phytohemagglutinin (PHA) stimulation was significantly decreased in UC patients, but the percentage of CD4+ and CD8+ cells in UC patients that showed apoptosis was not significantly different than that in the control group. Proliferative responses to IL-4 also suggested that a reduced responsiveness to this cytokine may be involved in UC. In conclusion, the impaired proliferative response to PHA of T lymphocytes from UC patients is not associated with an in vitro increase in the apoptotic response in CD4+ or CD8+ cells. A reduced IL-4 response may be involved in this peculiar mitogenic response. These changes may be pathogenic or a favorable adaptive mechanism.