Prevention of IL-6 signaling ameliorates toluene diisocyanate-induced steroid-resistant asthma

BackgroundAccumulating evidence indicated the crucial role for interleukin 6 (IL-6) signaling in the development of allergic asthma. Yet, the role of IL-6 signaling in toluene diisocyanate (TDI)-induced mixed granulocytic airway inflammation still remains unclear. Thus, the aims of this study were to dissect the role of IL-6 signaling and to evaluate the effect of tocilizumab on TDI-induced steroid-resistant asthma.MethodsTDI-induced asthma model was prepared and asthmatic mice were respectively given IL-6 monoclonal antibody, IL-6R monoclonal antibody (tocilizumab, 5 mg/kg, i.p. after each challenge) for therapeutic purposes or isotype IgG as control.ResultsTDI exposure just elevated IL-6R expression in the infiltrated inflammatory cells around the airway, but increased glycoprotein 130 expression in the whole lung, especially in bronchial epithelium. Moreover, TDI inhalation increased airway hyperresponsiveness (AHR) to methacholine, coupled with mixed granulocytic inflammation, exaggerated epithelial denudation, airway smooth muscle thickening, goblet cell metaplasia, extensive submucosal collagen deposition, dysregulated Th2/Th17 responses, as well as innate immune responses and raised serum IgE. And almost all these responses except for raised serum IgE were markedly ameliorated by the administration of IL-6 neutralizing antibody or tocilizumab, but exhibited poor response to systemic steroid treatment. Also, TDI challenge induced nucleocytoplasm translocation of HMGB1 and promoted its release in the BALF, as well as elevated lung level of STAT3 phosphorylation, which were inhibited by anti-IL-6 and anti-IL-6R treatment.ConclusionsOur data suggested that IL-6 monoclonal antibody and tocilizumab might effectively abrogate TDI-induced airway inflammation and remodeling, which could be used as a clinical potential therapy for patients with severe asthma.     

Successful treatment of a patient with Takayasu arteritis using a humanized anti-interleukin-6 receptor antibody

Takayasu arteritis (TA) is a chronic inflammatory disease that involves the aorta and its major branches. Since overproduction of interleukin-6 (IL-6) seems to play a pathogenic role in TA, we used the anti-IL-6 receptor (IL-6R) antibody tocilizumab to treat a 20-year-old woman with refractory active TA complicated by ulcerative colitis (UC). Treatment with tocilizumab improved the clinical manifestations of TA and the abnormal laboratory findings in this patient and ameliorated the activity of UC. These results indicate that IL-6R inhibition with tocilizumab might be a future treatment option for TA.     

Influence of humanized anti-IL-6R antibody, tocilizumab on the activity of soluble gp130, natural inhibitor of IL-6 signaling

Tocilizumab, humanized anti-IL-6R antibody is a novel anti-rheumatic drug. In the present study, we examined the influence of tocilizumab on the inhibitory activity of soluble gp130 (sgp130) against IL-6 signaling. BAF-h130 cells, human gp130 transfected mouse pro-B cell line, were cultured with the mixture with IL-6, sIL-6R and sgp130 for 72 h. BAF-h130 cells proliferated by the addition of both IL-6 and sIL-6R, but not IL-6 or sIL-6R alone. The proliferation induced by IL-6/sIL-6R complex was inhibited by sgp130 concentration-dependently. Tocilizumab inhibited IL-6/sIL-6R-induced cell proliferation. On the other hand, it did not affect the suppressive property of sgp130. To examine if tocilizumab can dissociate IL-6/sIL-6R/sgp130 complex, we established an ELISA system to detect IL-6/sIL-6R/sgp130 complex using anti-IL-6R coated ELISA plate. The results clearly indicated that ELISA system established was detectable IL-6/sIL-6R/sgp130 complex in a concentration dependent manner. Tocilizumab was added to IL-6/sIL-6R/sgp130 complex-fixed plate and then remaining IL-6/sIL-6R/sgp130 complexes on the plate were measured. The amount of IL-6/sIL-6R/sgp130 complexes on the plate was not changed by the addition of tocilizumab. In conclusion, tocilizumab exerts its inhibitory effect through the inhibition of IL-6R directly without affecting natural inhibitor sgp130.     

Blocking IL-25 signalling protects against gut inflammation in a type-2 model of colitis by suppressing nuocyte and NKT derived IL-13

Background

Interleukin-25 (IL-25) is a potent activator of type-2 immune responses. Mucosal inflammation in ulcerative colitis is driven by type-2 cytokines. We have previously shown that a neutralizing anti-IL-25 antibody abrogated airways hyperreactivity in an experimental model of lung allergy. Therefore, we asked whether blocking IL-25 via neutralizing antibodies against the ligand or its receptor IL-17BR could protect against inflammation in an oxazolone-induced mouse model of colitis.

Methods

Neutralizing antibodies to IL-25 or IL-17BR were administered to mice with oxazolone-induced colitis, a model of ulcerative colitis. The disease onset was evaluated by weight loss and degree of colon ulceration. Also, lamina propria and mesenteric lymph node (MLN) infiltrates were assessed for mucosal inflammation and cultured in vitro to determine cytokine production.

Results

We found that in oxazolone colitis IL-25 production derives from intestinal epithelial cells and that IL-17BR⁺ IL-13-producing natural killer T (NKT) cells and nuocytes drive the intestinal inflammation. Blocking IL-25 signalling considerably improved the clinical aspects of the disease, including weight loss and colon ulceration, and resulted in fewer nuocytes and NKT cells infiltrating the mucosa. The improved pathology correlated with a decrease in IL-13 production by lamina propria cells, a decrease in the production of other type-2 cytokines by MLN cells, and a decrease in blood eosinophilia and IgE.

Conclusion

IL-25 plays a pro-inflammatory role in the oxazolone colitis model, and neutralizing antibodies to IL-25 or IL-17BR can slow the ongoing inflammation in this disease. Because this model mimics aspects of human ulcerative colitis, these antibodies may represent potential therapeutics for reducing gut inflammation in patients.     

Mechanisms and pathologic significances in increase in serum interleukin-6 (IL-6) and soluble IL-6 receptor after administration of an anti-IL-6 receptor antibody, tocilizumab, in patients with rheumatoid arthritis and Castleman disease

Interleukin-6 (IL-6) plays pathologic roles in immune-inflammatory diseases such as rheumatoid arthritis (RA) and Castleman disease. By inhibiting IL-6 receptors (IL-6Rs), tocilizumab (a humanized anti-IL-6R antibody) ameliorates the symptoms of these diseases and normalizes acute-phase proteins, including C-reactive protein (CRP). We found that tocilizumab treatment increased serum levels of IL-6 and soluble IL-6R (sIL-6R). To investigate the pathologic significance of these increases, we analyzed the kinetics of serum IL-6 and sIL-6R and the proportion of sIL-6R saturated with tocilizumab after tocilizumab administration in patients with RA and Castleman disease and then compared the results with the CRP values. Serum IL-6 and sIL-6R markedly increased after tocilizumab administration in both RA and Castleman disease. As long as free tocilizumab was detectable, sIL-6R was saturated with tocilizumab and IL-6 signaling was completely inhibited. We concluded that it is likely that sIL-6R increased because its elimination half-life was prolonged by the formation of tocilizumab/sIL-6R immune complex, and that free serum IL-6 increased because IL-6R-mediated consumption of IL-6 was inhibited by the unavailability of tocilizumab-free IL-6R. We also concluded that the increased level of free IL-6 during tocilizumab treatment closely reflects the actual endogenous IL-6 production and true disease activity.     

Mast cell deficiency exacerbates inflammatory bowel symptoms in interleukin-10-deficient mice

AIM: To test the role of mast cells in gut inflammation and colitis using interleukin (IL)-10-deficient mice as an experimental model.METHODS: Mast cell-deficient (Kit^W-sh/W-sh) mice were crossbred with IL-10-deficient mice to obtain double knockout (DKO) mice. The growth, mucosal damage and colitis status of DKO mice were compared with their IL-10-deficient littermates.RESULTS: DKO mice exhibited exacerbated colitis compared with their IL-10-deficient littermates, as shown by increased pathological score, higher myeloperoxidase content, enhanced Th1 type pro-inflammatory cytokines and inflammatory signaling, elevated oxidative stress, as well as pronounced goblet cell loss. In addition, deficiency in mast cells resulted in enhanced mucosal damage, increased gut permeability, and impaired epithelial tight junctions. Mast cell deficiency was also linked to systemic inflammation, as demonstrated by higher serum levels of tumor necrosis factor α and interferon γ in DKO mice than that in IL-10-deficient mice.CONCLUSION: Mast cell deficiency in IL-10-deficient mice resulted in systematic and gut inflammation, impaired gut barrier function, and severer Th1-mediated colitis when compared to mice with only IL-10-deficiency. Inflammation and impaired gut epithelial barrier function likely form a vicious cycle to worsen colitis in the DKO mice.     

Inhibiting interleukin-6 in rheumatoid arthritis

Interleukin (IL)-6 is the most abundant proinflammatory cytokine in the circulation and synovial joints of patients with active rheumatoid arthritis. It has pivotal roles in the immune response and inflammation. In rheumatoid arthritis, it causes synovitis, joint destruction, and many systemic manifestations. Clinical trials of tocilizumab, a humanized anti-IL-6 receptor monoclonal antibody that blocks IL-6 signaling, have demonstrated therapeutic benefit. It heralds a new era of anticytokine therapy in rheumatoid arthritis.     

Both IL-12p70 and IL-23 are synthesized during active Crohn's disease and are down-regulated by treatment with anti-IL-12 p40 monoclonal antibody

BACKGROUND: Interleukin (IL)-12p70 and IL-23 are key T helper-1 (TH1) cytokines that drive the inflammation seen in numerous models of intestinal inflammation. These molecules contain an identical p40 chain that is bound to a p35 chain in IL-12 and a p19 chain in IL-23, making both potentially susceptible to modulation by an anti-IL-12p40 monoclonal antibody (mAb). METHODS: In the present study, we sought to determine whether active inflammation in Crohn's disease (CD) is associated with the increased synthesis of both of these cytokines and whether patients treated with an anti-IL-12p40 mAb down-regulate IL-23 as well as IL-12p70 as previous reported. RESULTS: To this end we initially determined that IL-12p70 secretion by control and CD antigen-presenting cells (macrophages) in lamina propria mononuclear populations is optimized by stimulation with CD40L and interferon-gamma. In subsequent studies using these stimulation conditions we found that patients with CD manifested both increased IL-12p70 and IL-23 secretion before anti-IL-12p40 mAb treatment and normal levels of secretion of these cytokines following cessation of treatment. Antigen-presenting cells in lamina propria mononuclear cells from ulcerative colitis patients, in contrast, produced only baseline levels of IL-23. Finally, we found that IL-23-induced T cell production of IL-17 and IL-6 are also greatly reduced after antibody treatment. The latter data are parallel to those from previous studies showing that anti-IL-12p40 down-regulates IFN-gamma and tumor necrosis factor-alpha secretion. CONCLUSIONS: We conclude that CD but not ulcerative colitis is associated with high levels of both IL-12p70 and IL-23 secretion as well as the secretion of downstream effector cytokines, and that this cytokine production is down-regulated following administration of IL-12p40 mAb.     

Remission-inducing effect of anti-TNF monoclonal antibody in TNBS colitis: mechanisms beyond neutralization?

BACKGROUND: Tumor necrosis factor (TNF) plays an important role in the pathogenesis of several inflammatory diseases. Its expression is increased in inflamed mucosa of Crohn's disease patients and anti-TNF treatment improves mucosal inflammation. Besides neutralization, induction of apoptosis of monocytes/macrophages and T cells is thought to be an important mechanism of action of the anti-TNF monoclonal antibody therapy. The aim was to investigate the pathogenic role of TNF in hapten-induced colitis models and to study the relationship between apoptosis induction and disease remission. METHODS: In 2 murine colitis models (trinitrobenzene sulphonic acid, TNBS, and oxazolone colitis), mice were injected daily with anti-TNF monoclonal antibody (mAb). Macrophages were collected from lamina propria of TNBS colitis mice. 7AAD and anti-active-caspase-3 staining were used to study DNA degradation and intracellular caspase activation. A pan-caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), was given to a subgroup of the colitis mice. RESULTS: Treatment with anti-TNF effectively reduced intestinal mucosal inflammation in TNBS colitis but not in oxazolone colitis. Effectiveness was evidenced by a more rapid recovery of body weight and reduced cell infiltration, and downregulation of proinflammatory cytokines interferon-gamma (IFN-gamma), TNF, and IL-18 at the mRNA level. Apoptosis was induced in lamina propria macrophages after treatment with anti-TNF, and it was abrogated through short-term pretreatment with Z-VAD-FMK. CONCLUSION: Anti-TNF downregulates proinflammatory cytokines and decreases cell infiltration in the bowel after TNBS application. The remission-inducing effect of anti-TNF may partly rely on apoptosis induction.     

Poor diagnostic value of colonic CD44v6 expression and serum concentrations of its soluble form in the differentiation of ulcerative colitis from Crohn's disease

Background—Increased expression ofCD44v6 on colonic crypt epithelial cells in ulcerative colitis has beensuggested as a diagnostic tool to distinguish ulcerative colitis fromcolonic Crohn's disease.
Aims—To investigate colonicCD44v6 expression and serum concentrations of soluble CD44v6 (sCD44v6)in patients with ulcerative colitis and Crohn's disease.
Methods—Colonic biopsy samples wereobtained from 16 patients with ulcerative colitis, 13 with ileocolonicCrohn's disease, and 10 undergoing polypectomy. Serum samples wereobtained from 15 patients with active ulcerative colitis, 20 withactive Crohn's disease, and 20 healthy donors. Colonic CD44v6expression was evaluated immunohistochemically by monoclonal antibody2F10 and the higher affinity monoclonal antibody VFF18. Serum sCD44v6concentrations were measured by ELISA.
Results—2F10 stained colonicepithelium of inflamed ulcerative colitis and Crohn's disease samplesin 80% and 40% of cases, respectively, and VFF18 in 95% and 87%,respectively. Both monoclonal antibodies displayed a sensitivity andspecificity of 60% and 87% to differentiate ulcerative colitis fromcolonic Crohn's disease. Serum concentrations of sCD44v6 were lower inpatients with ulcerative colitis (median 153 ng/ml; interquartile range(IQR) 122-211) compared with Crohn's disease (219; IQR 180-243) andhealthy donors (221; IQR 197-241 (p=0.002)). Its sensitivity andspecificity to discriminate ulcerative colitis from Crohn's diseasewas 75% and 71%, respectively.
Conclusion—Colonic CD44v6 and serumsCD44v6 concentrations do not facilitate reliable differentialdiagnosis between ulcerative colitis and Crohn's disease.

Keywords:CD44 variant 6; differential diagnosis; immunohistochemistry; soluble CD44v6

     

Interleukin-12 and Th1 immune response in Crohn＇s disease： Pathogenetic relevance and therapeutic inplication

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastrointestinal tract that share clinical and pathological characteristics. The most accredited hypothesis is that both CD and UC result from a deregulated mucosal immune response to normal constituents of the gut microflora. Evidence, however, indicates that the main pathological processes in these two diseases are distinct. In CD, the tissue-damaging inflammatory reaction is driven by activated type 1 helper T-cell (Th1), whereas a humoral response predominates in UC. Consistently, a marked accumulation of macrophages making interleukin (IL)-12, the major Th1-inducing factor, is seen in CD but not in UC mucosa. Preliminary studies also indicate that administration of a monoclonal antibody blocking the IL-12/p40 subunit can be useful to induce and maintain clinical remission in CD patients. Notably, the recently described IL-23 shares the p40 subunit with IL-12, raising the possibility that the clinical benefit of the anti-IL-12/p40 antibody in CD may also be due to the neutralization of IL-23 activity. This review summarizes the current information on the expression and functional role of IL-12 and IL-12-associated signaling pathways both in patients with CD and experimental models of colitis, thus emphasizing major differences between IL-12 and IL-23 activity on the development of intestinal inflammation.     

The combination of IL-6 and its soluble receptor is associated with the response of rheumatoid arthritis patients to tocilizumab

BackgroundIL-6 contributes significantly to the chronic inflammatory process of rheumatoid arthritis (RA). Tocilizumab, a humanized anti-human IL-6 receptor antibody that blocks the signaling originated by the IL-6/IL-6R complex, is an effective treatment. However, predictors of the response to tocilizumab are still required. We aimed to combine IL-6 and soluble IL-6R (sIL-6R) levels to identify groups of responses.MethodsHeparinized blood and clinical data from 63 RA patients were collected before treatment and after 3 and 6 months. Two-step clustering (SPSS v.18) was used to establish the relationship between IL-6 and sIL-6R. Then, we compared European League Against Rheumatism (EULAR) response criteria with remission achievement in the groups of patients.ResultsThree statistical significant clusters of RA patients (i.e., g1, g2, and g3) were defined by serum concentrations of IL-6 and sIL-6R at baseline. All groups of RA patients had higher IL-6 and sIL-6R levels than healthy donors. The levels of IL-6 expressed as median (IQR) in g1 patients were 124(90–183) pg/ml, in g2 12.3(4.4–24) pg/ml, and in g3 60.1(30–146) pg/ml (p < 0.001). The levels of sIL-6R expressed as mean ± sd in g1 patients were 250.5 ± 72 ng/ml, in g2 269.1 ± 125 ng/ml, and in g3 732.7 ± 243 ng/ml (p < 0.001). Disease activity score (DAS)28, C-reactive protein, and erythrocyte sedimentation rate were comparable in the three groups at baseline. Disease duration in g3 was the longest (median(IQR) years: g1 = 11(5–15), g2 = 12(8–20), and g3 23(16–26); p = 0.006), with years of disease evolution being correlated with sIL-6R levels (R = 0.417, p < 0.001). Simple and Clinical Disease Activity Index (SDAI and CDAI) decreased significantly in the three groups. However, EULAR response criteria and remission achievement at 6 m was different in the three groups (p = 0.03 and 0.04, respectively). In all. 17 out of the 18 patients in g1 had a good or moderate response to tocilizumab. Conversely, the percentage of patients with no response to tocilizumab was higher in g3 than in g1 and g2. We also observed different changing patterns of IL-6 and sIL-6R levels among the three groups.ConclusionsRA patients could be easily stratified prior to therapeutic intervention with two molecules related to the pathway blocked by tocilizumab. G1 patients, who had the best response to tocilizumab, had the highest level of IL-6 and the lowest level of sIL-6R.     

Signaling through interleukin-6 receptor supports blast cell proliferation in acute myeloblastic leukemia

Abstract: The role of the interleukin-6/interleukin-6 receptor (IL-6/IL-6R) system in regulating blast cell growth in 8 acute myeloblastic leukemia (AML) patient-derived cell lines was investigated. As they all expressed IL- 6R and as none of them responded to exogenous IL-6 under conventional serum-supplemented culture conditions, we investigated whether signaling through IL-6R plays any role in maintaining their spontaneous colony growth. This was done by treating the cells with monoclonal antibodies made against the ligand-specific IL-6R α-chain or the signal transducer gp130. In serum-supplemented cultures inhibition of gp 130 function did not affect the cell line growth, whereas anti-IL-6R α-chain antibody reduced colony growth. While some of the cell lines also showed similar growth characteristics in a serum-free environment, some others changed their growth pattern and stopped responding to anti-IL-6R α-chain treatment. At the same time, these cell lines also began to respond to exogenously added IL-6 and, interestingly, were stimulated by anti-gp130 antibody. Hence, in some of the blast cells, clonogenic cell growth seemed to be also negatively controlled by an endogenously produced growth-depressing cytokine or cytokines that utilize gp130. All the cell lines, whether cultured in the presence or absence of serum expressed IL-6 both at mRNA and protein level. The current results indicate that AML cells can use IL-6 as a growth stimulating factor, supplied either paracrinely or autocrinely. This could implicate the use of anti-IL-6R α-chain antagonists in AML treatment, not IL-6.     

In vitro anticolon antibody production by mucosal or peripheral blood lymphocytes from patients with ulcerative colitis.

Serum anticolon antibody and in vitro anti-colon antibody production by peripheral blood and mucosal lymphocytes was investigated in patients with ulcerative colitis. The frequency of serum anticolon antibody was 71% in 41 patients with ulcerative colitis, estimated by enzyme linked immunosorbent assay (ELISA) using isolated rat colon epithelial cells. This finding confirms our previous report on the frequency of serum anticolon antibody detected by flow cytometry analysis. The estimated frequencies of IgG anticolon antibody secreting cells were 1.5-12.5/10(6) cells in the colonic mucosa and 0.1-0.5/10(6) cells in peripheral blood, from patients with ulcerative colitis when Epstein-Barr virus (EBV) was used as a B cell polyclonal activator. Poisson analysis of limiting dilution culture showed that about one per 140 IgG cells in the colonic mucosa synthesised anticolon antibody. Two monoclonal IgG antibodies were obtained from EBV transformed anticolon antibody secreting cells by limiting dilution method. One reacted with goblet cells in the intestine, and the other reacted mainly with colonic epithelial cells. These results suggest that heterogeneous anticolon antibodies are present in patients with ulcerative colitis and that colonic mucosa may be the main source of anticolon antibody. Local autoimmune reaction might have an important role in causing the inflammation of colonic mucosa in this disease.     

Successful treatment of a patient with takayasu arteritis using a humanized anti–interleukin‐6 receptor antibody

Takayasu arteritis (TA) is a chronic inflammatory disease that involves the aorta and its major branches. Since overproduction of interleukin‐6 (IL‐6) seems to play a pathogenic role in TA, we used the anti–IL‐6 receptor (IL‐6R) antibody tocilizumab to treat a 20‐year‐old woman with refractory active TA complicated by ulcerative colitis (UC). Treatment with tocilizumab improved the clinical manifestations of TA and the abnormal laboratory findings in this patient and ameliorated the activity of UC. These results indicate that IL‐6R inhibition with tocilizumab might be a future treatment option for TA.     

Critical role of IL-17 receptor signaling in acute TNBS-induced colitis

BACKGROUND: Inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis are characterized by recurrent inflammation in the gastrointestinal tract. Infiltration of CD4 lymphocytes and neutrophils is one of the predominant features of IBD. MATERIALS AND METHODS: Recently, interleukin (IL)-23 and the downstream T cell-derived cytokine IL-17 have been found to be elevated in intestinal tissue and serum of IBD patients. However, the role of IL-17 and IL-17R signaling in gut inflammation is unknown. To examine this role, we investigated gut inflammation in wild-type or IL-17R knockout mice. RESULTS: Using a model of acute trinitrobenzenesulfonic acid (TNBS)-induced colitis, we found that IL-17 was produced in colon tissue at 24 and 48 hours and that IL-17R knockout mice were significantly protected against TNBS-induced weight loss, IL-6 production, colonic inflammation, and local macrophage inflammatory protein-2 induction. This protection occurred in the presence of equivalent induction of local IL-23 and higher levels of IL-12p70 and interferon-gamma in IL-17R knockout mice compared with wild-type mice. Moreover, IL-17R knockout mice showed reduced tissue myeloperoxidase activity. Furthermore, overexpression of an IL-17R IgG1 fusion protein significantly attenuated colonic inflammation after acute TNBS. CONCLUSIONS: These results demonstrate that IL-17R signaling plays a critical role in the development of TNBS-induced colitis and may represent a target for therapeutic intervention for IBD.     

Macrophage-derived IL-18-mediated intestinal inflammation in the murine model of Crohn's disease

BACKGROUND & AIMS: Crohn's disease (CD) is associated with an increased number of infiltrating macrophages, which release a variety of proinflammatory cytokines. Interleukin (IL)-18 has been implicated in the modulation of mucosal CD4(+) T cells towards Th1 responses, which are implicated in the pathogenesis of CD. Here we assess the role of macrophages and of IL-18 in the murine model of intestinal inflammation that mimics the immunologic characteristics of human CD. METHODS: Colitis was induced in C57BL/6 mice immunized with 2,4,6-trinitrobenzene sulfonic acid (TNBS) followed by rectal administration of TNBS in ethanol. Mice were treated with either an antibody directed against macrophages conjugated to the ribosome-inactivating protein saporin (anti-Mac-1-saporin) or with a neutralizing antibody against IL-18. In addition, we assessed whether an identical TNBS immunization/challenge protocol could induce colitis in IL-18(-/-) mice. RESULTS: The colonic mucosa of TNBS-treated mice was marked by infiltration of Mac-1-positive macrophages and up-regulation of IL-18. The administration of the anti-Mac-1-saporin antibody or the neutralizing anti-IL-18 antibody resulted in a dramatic attenuation of mucosal inflammation in this model. In addition, TNBS was unable to induce significant colitis in the IL-18(-/-) mice. CONCLUSIONS: Our data underscore the pivotal role of macrophages, and the macrophage-derived IL-18, in the establishment of TNBS-induced colitis in mice. Our results highlight the potential use of therapy directed against IL-18 in the treatment of patients with CD.     

Transgenic Expression of Vitamin D Receptor in Gut Epithelial Cells Ameliorates Spontaneous Colitis Caused by Interleukin-10 Deficiency

Background

Vitamin D deficiency is common in patients with inflammatory bowel diseases. The vitamin D receptor (VDR) is a nuclear hormone receptor mediating the activity of vitamin D hormone. Our previous studies showed that intestinal epithelial VDR signaling inhibits colitis by protecting the mucosal epithelial barrier, and this activity is independent of non-epithelial immune VDR actions. Interleukin (IL)-10-deficient mouse is a chronic colitis model that develops colitis due to aberrant immune responses. Here we used IL-10 null (IL-10KO) model to assess the anti-colitic activity of epithelial VDR in the setting of an aberrant immune system.

Methods

We crossed IL-10KO mice with villin promoter-driven human (h) VDR transgenic (Tg) mice to generate IL-10KO mice that carry the hVDR transgene in intestinal epithelial cells (IL-10KO/Tg). IL-10KO and IL-10KO/Tg littermates were studied in parallel and followed for up to 25 weeks.

Results

By 25 weeks of age, accumulatively 79 % IL-10KO mice developed prolapse, whereas only 40 % IL-10KO/Tg mice did so (P < 0.001). Compared with IL-10KO mice, IL-10KO/Tg littermates showed markedly reduced mucosal inflammation in both small and large intestines, manifested by attenuation in immune cell infiltration and histological damage and a marked decrease in pro-inflammatory cytokine production. IL-10KO/Tg mice also showed reduced intestinal epithelial cell apoptosis as a result of diminished PUMA induction and caspase 3 activation.

Conclusion

These observations demonstrate that targeting hVDR expression to intestinal epithelial cells is sufficient to attenuate spontaneous colitis caused by an ill-regulated immune system, confirming a critical role of the epithelial VDR signaling in blocking colitis development.