Immunopathogenesis of Crohn's Disease

The Role of TGF-β, Activin and Follistatin in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory condition predominantly affecting the gastrointestinal (GI) tract. An increasing prevalence of IBD has been observed globally. The pathogenesis of IBD includes a complex interplay between the intestinal microbiome, diet, genetic factors and immune responses. The consequent imbalance of inflammatory mediators ultimately leads to intestinal mucosal damage and defective repair. Growth factors, given their specific roles in maintaining the homeostasis and integrity of the intestinal epithelium, are of particular interest in the setting of IBD. Furthermore, direct targeting of growth factor signalling pathways involved in the regeneration of the damaged epithelium and the regulation of inflammation could be considered as therapeutic options for individuals with IBD. Several members of the transforming growth factor (TGF)-β superfamily, particularly TGF-β, activin and follistatin, are key candidates as they exhibit various roles in inflammatory processes and contribute to maintenance and homeostasis in the GI tract. This article aimed firstly to review the events involved in the pathogenesis of IBD with particular emphasis on TGF-β, activin and follistatin and secondly to outline the potential role of therapeutic manipulation of these pathways.

Inhomogeneous Diastereomeric Composition of Mongersen Antisense Phosphorothioate Oligonucleotide Preparations and Related Pharmacological Activity Impairment

Mongersen is a 21-mer antisense oligonucleotide designed to downregulate Mothers against decapentaplegic homolog 7 (SMAD7) expression to treat Crohn's disease. Mongersen was manufactured in numerous batches at different scales during several years of clinical development, which all appeared identical, using common physicochemical analytical techniques, while only phosphorous-31 nuclear magnetic resonance (³¹P-NMR) in solution showed marked differences. Close-up analysis of 27 mongersen batches revealed marked differences in SMAD7 downregulation in a cell-based assay. Principal component analysis of ³¹P-NMR profiles showed strong correlation with SMAD7 downregulation and, therefore, with pharmacological efficacy in vitro. Mongersen contains 20 phosphorothioate (PS) linkages, whose chirality (Rp/Sp) was not controlled during manufacturing. A different diastereomeric composition throughout batches would lead to superimposable analytical data, but to distinct ³¹P-NMR profiles, as indeed we found. We tentatively suggest that this may be the origin of different biological activity. As similar manifolds are expected for other PS-based oligonucleotides, the protocol described here provides a general method to identify PS chirality issues and a chemometric tool to score each preparation for this elusive feature.

Nutritional Therapy Strategies in Pediatric Crohn's Disease

The increase in incidences of pediatric Crohn's Disease (CD) worldwide has been strongly linked with dietary shifts towards a Westernized diet, ultimately leading to altered gut microbiota and disturbance in intestinal immunity and the metabolome. Multiple clinical studies in children with CD have demonstrated the high efficacy of nutritional therapy with exclusive enteral nutrition (EEN) to induce remission with an excellent safety profile. However, EEN is poorly tolerated, limiting its compliance and clinical application. This has spiked an interest in the development of alternative and better-tolerated nutritional therapy strategies. Several nutritional therapies have now been designed not only to treat the nutritional deficiencies seen in children with active CD but also to correct dysbiosis and reduce intestinal inflammation. In this review, we report the most recent insights regarding nutritional strategies in children with active CD: EEN, partial enteral nutrition (PEN), Crohn's disease exclusive diet (CDED), and CD treatment-with-eating diet (CD-TREAT). We describe their setup, efficacy, safety, and (dis)advantages as well as some of their potential mechanisms of action and perspectives. A better understanding of different nutritional therapeutic options and their mechanisms will yield better and safer management strategies for children with CD and may address the barriers and limitations of current strategies in children.

Enteral Nutrition Supplemented with Transforming Growth Factor-β, Colostrum, Probiotics, and Other Nutritional Compounds in the Treatment of Patients with Inflammatory Bowel Disease

Enteral nutrition seems to play a significant role in the treatment of both adults and children with active Crohn's disease, and to a lesser degree in the treatment of patients with active ulcerative colitis. The inclusion of some special factors in the enteral nutrition formulas might increase the rate of the efficacy. Actually, enteral nutrition enriched in Transforming Growth Factor-β reduced the activity index and maintained remission in patients with Crohn's disease. In addition, a number of experimental animal studies have shown that colostrum exerts a significantly positive result. Probiotics of a special type and a certain dosage could also reduce the inflammatory process in patients with active ulcerative colitis. Therefore, the addition of these factors in an enteral nutrition formula might increase its effectiveness. Although the use of these formulas is not supported by large clinical trials, it could be argued that their administration in selected cases as an exclusive diet or in combination with the drugs used in patients with inflammatory bowel disease could benefit the patient. In this review, the authors provide an update on the role of enteral nutrition, supplemented with Transforming Growth Factor-β, colostrum, and probiotics in patients with inflammatory bowel disease.

Exclusive enteral nutrition in Crohn's disease: Evidence and practicalities

Exclusive enteral nutrition (EEN) is the first line therapy for paediatric Crohn's disease, providing a complete nutritional feed whilst simultaneously inducing remission in up to 80% of cases. The effect of EEN on systemic/local intestinal immune function and subsequent inflammation (including barrier permeability, direct anti-inflammatory effects and cytokine signalling pathways), alongside changes in the microbiome (specific species and broad taxonomic shifts, functional changes) are becoming clearer, however the exact mechanism for induction of remission in Crohn's disease remains uncertain. The evidence of efficacy in paediatric Crohn's disease is strong, with selected adult populations also benefiting from EEN. However despite recommendations from all major societies (ECCO, ESPGHAN, NASPGHAN and ESPEN) first-line use of EEN is varied and Europe/Australasia/Canada show significantly more routine use than other parts of North America. Growth and nutritional status are significantly improved with EEN compared to corticosteroids but long-term outcomes are sparse. This review discusses the evidence underlying the use of EEN, highlighting the mechanisms thought to underlie how EEN induces remission in Crohn's disease, when and how to use EEN, including practical issues in both paediatric and adult practice (formulation, compliance, volumes and administration), and summarises the ongoing research priorities.

The role of enteral nutrition in patients with inflammatory bowel disease: current aspects

Enteral nutrition (EN) is considered to be of great importance in patients with inflammatory bowel disease (IBD) and nutritional problems. This comprehensive review is aiming to provide the reader with an update on the role of EN in IBD patients. EN can reduce Crohn's disease (CD) activity and maintain remission in both adults and children. Nutritional support using liquid formulas should be considered for CD patients and in serious cases of ulcerative colitis (UC), especially for those who may require prolonged cycles of corticosteroids. Given that the ultimate goal in the treatment of CD is mucosal healing, this advantage of EN over corticosteroid treatment is valuable in therapeutic decision-making. EN is indicated in active CD, in cases of steroid intolerance, in patient's refusal of steroids, in combination with steroids in undernourished individuals, and in patients with an inflammatory stenosis of the small intestine. No differences between the efficiency of elemental diets and nonelemental formulas have been noticed. EN must be the first choice compared to TPN. EN has a restricted value in the treatment of patients with large bowel CD. In conclusion, it seems important not to underestimate the role of nutrition as supportive care in patients with IBD.

Renal transport of organic anions and cations

Organic anions and cations (OAs and OCs, respectively) comprise an extraordinarily diverse array of compounds of physiological, pharmacological, and toxicological importance. The kidney, primarily the renal proximal tubule, plays a critical role in regulating the plasma concentrations of these organic electrolytes and in clearing the body of potentially toxic xenobiotics agents, a process that involves active, transepithelial secretion. This transepithelial transport involves separate entry and exit steps at the basolateral and luminal aspects of renal tubular cells. Basolateral and luminal OA and OC transport reflects the concerted activity of a suite of separate proteins arranged in parallel in each pole of proximal tubule cells. The cloning of multiple members of several distinct transport families, the subsequent characterization of their activity, and their subcellular localization within distinct regions of the kidney, now allows the development of models describing the molecular basis of the renal secretion of OAs and OCs. New information on naturally occurring genetic variation of many of these processes provides insight into the basis of observed variability of drug efficacy and unwanted drug-drug interactions in human populations. The present review examines recent work on these issues.

Optimal use and cost-effectiveness of biologic therapies in inflammatory bowel disease

Inflammatory bowel diseases (IBD), namely Crohn's disease and ulcerative colitis, are burdened by high medical costs which are mostly dependent on hospital inpatient treatment. New biologic therapies, which target specific cytokines in the inflammatory cascade leading to the intestinal lesions, including tumor necrosis factor (TNF)-α, have revolutionized the management of IBD by offering a therapeutic chance to patients in whom conventional therapies failed. However, the relatively high costs of biologic drugs, together with their potential toxicity due to infections and malignancies, have led to debate regarding their indiscriminate use in IBD patients. The purpose of this review is to deal with the optimal use and cost-effectiveness of the two main monoclonal anti-TNF-α agents currently used in the management of IBD patients, i.e. the chimeric human/murine antibody infliximab and the fully human antibody adalimumab.

Beyond epithelial to mesenchymal transition: a novel role for the transcription factor Snail in inflammation and wound healing

INTRODUCTION

Snail, a transcription factor linked to epithelial to mesenchymal transition (EMT) during embryonic development and tumor progression, is associated with migration of cells. During inflammation and tissue injury, cell movement is also observed to provide the first line of defense against bacteria and to promote wound healing. Therefore, we studied the function of Snail in activated macrophages in a variety of inflammatory processes.

MATERIALS AND METHODS

In this study, we examined the expression and localization of Snail during inflammation and tissue injury in rats and human tissue specimens, by immunohistochemistry, Western blot, and real-time PCR. We investigated Snail expression after stimulation of macrophages with TGF-beta1, LPS, Interleukin-8, and MMP-3 in vitro. To further understand the role of Snail in activated macrophages, we used Stealth siRNA against Snail, transfected the human macrophage cell line THP-1, and measured migration of cells in an in vitro invasion assay.

RESULTS AND DISCUSSION

We found a strong, transient, and time-dependent activation of Snail in migrating macrophages at the sites of injury in vivo and in vitro, as well as in patients with inflammatory bowel disease. Furthermore, we showed that induction of Snail in macrophages is dependent on TGF-beta1 signaling pathway. Downregulation of Snail by Stealth siRNA led to impaired migration of THP-1 cells in an invasion assay after stimulation with TGF-beta1.

CONCLUSION

We conclude that TGF-beta1 induced migration of activated macrophages during inflammation and wound healing is mediated by snail. These results give insights in a novel EMT-like mechanism present in immune cell movement during tissue injury.

Subclinical intestinal inflammation in patients with Crohn's disease following bowel resection: a smoldering fire

BACKGROUND/AIMS

Fecal lactoferrin is the direct expression of intestinal inflammation in Crohn's disease (CD). The aim of this study was to analyze the in vivo intimate correlation between intestinal and systemic inflammation in CD patients in clinical remission following bowel resection. The secondary end point was to evaluate the prognostic value of lactoferrin levels and serum cytokines in terms of need of surgery for recurrence in these patients.

PATIENTS AND METHODS

Fecal lactoferrin and serum cytokine (interleukin (IL)-1beta, IL-6, IL-12, tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1) levels were assessed; hematological and biochemical investigations were carried out, and Crohn's Disease Activity Index was evaluated in the 36 patients who had undergone bowel resection. The prognostic value of lactoferrin and cytokine levels in terms of surgical recurrence was assessed by re-calling patients after 24 months from the enrolment in the study.

RESULTS

All patients, evaluated after a follow-up of 36 +/- 5 months, were in clinical remission. Fecal lactoferrin levels were found to be significantly correlated with IL-6 (R = 0.431, p = 0.025) and C-reactive protein (CRP; R = 0.507, p = 0.007), while no correlation was observed between lactoferrin and IL-1beta, IL-12, TNF-alpha, or TGF-beta1. Reoperation for anastomotic recurrence tended to occur significantly more frequently in patients with higher IL-6 (p = 0.10).

CONCLUSIONS

Subclinical intestinal inflammation, expressed by fecal lactoferrin, seems to keep the systemic inflammation alive in CD patients through the IL-6-CRP cascade. IL-6 seems to be predictive of the outcome of CD patients undergoing surgery.

Heat shock protein-derived T-cell epitopes contribute to autoimmune inflammation in pediatric Crohn's disease

Pediatric Crohn's disease is a chronic auto inflammatory bowel disorder affecting children under the age of 17 years. A putative etiopathogenesis of Crohn's disease (CD) is associated with disregulation of immune response to antigens commonly present in the gut microenvironment. Heat shock proteins (HSP) have been identified as ubiquitous antigens with the ability to modulate inflammatory responses associated with several autoimmune diseases. The present study tested the contribution of immune responses to HSP in the amplification of autoimmune inflammation in chronically inflamed mucosa of pediatric CD patients. Colonic biopsies obtained from normal and CD mucosa were stimulated with pairs of Pan HLA-DR binder HSP60-derived peptides (human/bacterial homologues). The modulation of RNA and protein levels of induced proinflammatory cytokines were measured. We identified two epitopes capable of sustaining proinflammatory responses, specifically TNF〈 and IFN© induction, in the inflamed intestinal mucosa in CD patients. The responses correlated positively with clinical and histological measurements of disease activity, thus suggesting a contribution of immune responses to HSP in pediatric CD site-specific mucosal inflammation.

ESPEN Guidelines on Parenteral Nutrition: gastroenterology

Undernutrition as well as specific nutrient deficiencies has been described in patients with Crohn's disease (CD), ulcerative colitis (UC) and short bowel syndrome. In the latter, water and electrolytes disturbances may be a major problem. The present guidelines provide evidence-based recommendations for the indications, application and type of parenteral formula to be used in acute and chronic phases of illness. Parenteral nutrition is not recommended as a primary treatment in CD and UC. The use of parenteral nutrition is however reliable when oral/enteral feeding is not possible. There is a lack of data supporting specific nutrients in these conditions. Parenteral nutrition is mandatory in case of intestinal failure, at least in the acute period. In patients with short bowel, specific attention should be paid to water and electrolyte supplementation. Currently, the use of growth hormone, glutamine and GLP-2 cannot be recommended in patients with short bowel.

Hydrogen mediates suppression of colon inflammation induced by dextran sodium sulfate

By its antioxidant effect, molecular hydrogen gas (H2) was reported to protect organs from tissue damage induced by ischemia reperfusion. To evaluate its anti-inflammatory effects, we established a mouse model of human inflammatory bowel disease (IBD) by supplying mice with water containing (1) dextran sodium sulfate (DSS) (5%), (2) DSS (5%) and H2, or (3) H2 only ad libitum up to 7 days. At day-7, DSS-induced pathogenic outcomes including, loss of body weight, increase of colitis score, pathogenic shortening of colon length, elevated level of IL-12, TNF-alpha and IL-1beta in colon lesion, were significantly suppressed by the addition of H2 to DSS solution. Histological analysis also revealed that the DSS-mediated colonic tissue destruction accompanied by macrophage infiltration was remarkably suppressed by H2. Therefore, the present study indicated that H2 can prevent the development of DSS-induced colitis in mice.

Mucosal T-cell responses to HIV: responding at the front lines

Mucosal surfaces of the body serve as the major portal of entry for human immunodeficiency virus (HIV). These tissues also house a majority of the body's lymphocytes, including the CD4(+) T cells that are the major cellular target for HIV infection. Mucosal surfaces are defended by innate and adaptive immune mechanisms, including secreted antibodies and CD8(+) cytotoxic T cells (CTL). CTL in mucosal lymphoid tissues may serve to limit viral replication, decreasing the host's viral burden as well as reducing the likelihood of sexual transmission to a naïve host. This review summarizes recent literature on HIV-specific T-cell responses in mucosal tissues, with an emphasis on the gastrointestinal tract.

The effects of NOD2/CARD15 mutations on the function of the intestinal barrier

NOD2 variants have been identified to be a susceptibility factor for Crohn's disease. The NOD2 protein is an intracellular sensor of the bacterial wall product muramyl dipeptide (MDP) and activates the transcription factor NF-kappaB upon MDP-binding. NOD2 variants are associated with reduced NF-kappaB activation and reduced production of epithelial derived antibacterial peptides such as defensins. A reduced expression of defensins is described and found in patients with Crohn's disease and ulcerative colitis especially when NOD2 variants are present. Furthermore recent evidence from mouse models suggests that the ability of intestinal epithelial cells to activate NF-kappaB upon bacterial stimulation protects from mucosal inflammation. Taken together these data indicate that NOD2 mediated NF-kappaB activation, subsequent induction of anti-microbial peptides such as defensins and induction of cytokine expression are essential for the function of the intestinal barrier and for the prevention of bacterial translocation. The data indicate why a defect in the induction of this acute defense response is associated with chronic inflammation. Invading bacteria that cannot be readily detected and eliminated may start a backup mechanism of inflammation finally resulting in chronic inflammatory reaction followed by further impairment of the mucosal barrier.

Efficacy and safety of oral beclomethasone dipropionate for ileal or ileal-right colon Crohn's disease of mild-to-moderate activity or in remission: Retrospective study

Although conventional glucocorticosteroids are the main treatments for active Crohn's disease, several problems are associated with steroid dependence and steroid-related adverse events. To assess the efficacy and safety of oral beclomethasone dipropionate (BDP) coated tablets in adults with mild-to-moderate Crohn's disease. Thirty-four patients (age 18-70years) with a diagnosis of Crohn's disease confirmed by conventional criteria (barium enema, clinical criteria, colonoscopy, histology) were retrospectively evaluated in the study. All subjects received a treatment schedule with BDP 5-10mg/day for 24weeks. BDP significantly (p=0.005) reduced mean Crohn's Disease Activity Index (CDAI) score from 169.6 at baseline to 123.2 after 24weeks. Clinical success was evident at 24weeks in 66.7% of patients with initial active disease, and remission was maintained at week 24 in 93.8% of patients with remission at baseline. Overall, female non-smokers had the best response to treatment. BDP was well tolerated and the only adverse events observed were nausea (n=1), facial erythema (n=1) and one patient with raised fasting blood glucose level. These results clearly suggest that oral BDP coated tablets are effective and safe for treatment of mild-to-moderate Crohn's disease of ileal or ileal-right colonic localisation.

Induction of IL-13 triggers TGF-beta1-dependent tissue fibrosis in chronic 2,4,6-trinitrobenzene sulfonic acid colitis

To investigate the immunopathogenesis of inflammation-associated fibrosis, we analyzed the chronic colitis and late-developing fibrosis occurring in BALB/c mice administered weekly doses of intrarectal 2,4,6-trinitrobenzene sulfonic acid. We showed first in this model that an initial Th1 response involving IL-12p70 and IFN-gamma subsides after 3 wk to be supplanted by an IL-23/IL-25 response beginning after 4-5 wk. This evolution is followed by gradually increasing production of IL-17 and cytokines ordinarily seen in a Th2 response, particularly IL-13, which reaches a plateau at 8-9 wk. In vitro stimulation studies suggest that this IL-13 production is dependent on IL-23 and IL-25, but not on IL-12p70. We then show that IL-13 production results in the induction of an IL-13R formerly thought to function only as a decoy receptor, IL-13Ralpha(2), and this receptor is critical to the production of TGF-beta(1) and the onset of fibrosis. Thus, if IL-13 signaling through this receptor is blocked by administration of soluble IL-13Ralpha(2)-Fc, or by administration of IL-13Ralpha(2)-specific small interfering RNA, TGF-beta(1) is not produced and fibrosis does not occur. These studies show that in chronic 2,4,6-trinitrobenzene sulfonic acid colitis, fibrosis is dependent on the development of an IL-13 response that acts through a novel cell surface-expressed IL-13R to induce TGF-beta(1). A similar mechanism may obtain in certain forms of human inflammatory bowel disease.

Deficiency of invariant NK T cells in Crohn's disease and ulcerative colitis

The aim of this study was to investigate whether immunoregulatory invariant NK T cells are deficient in Crohn's disease or ulcerative colitis. Blood was collected for flow cytometry from 106 Crohn's disease, 91 ulcerative colitis, and 155 control subjects. Invariant NK T cells were assessed by Valpha24 and (alpha-galactosylceramide/CD1d tetramer markers. Intracellular cytokine was measured after in vitro anti-CD3 antibody stimulation. Valpha24+ T cells were quantified in ileocolonic biopsies as mRNA by real-time PCR and by immunofluorescence. Circulating invariant NK T cells were 5.3% of the control levels in Crohn's (P < 0.001) and 7.9% of the control levels in ulcerative colitis (P < 0.001). Interleukin-4 production was impaired in Crohn's disease and ulcerative colitis. Intestinal Valpha24 mRNA expression was 7% in Crohn's disease (P < 0.05) and 9% in ulcerative colitis (P < 0.05). Intestinal Valpha24+ T cells were 23% in Crohn's disease but not reduced in ulcerative colitis. We conclude that invariant NK T cells are deficient in Crohn's disease and in ulcerative colitis.

Sinonasal involvement as a rare extraintestinal manifestation of Crohn's disease

Crohn's disease is a chronic idiopathic slowly developing transmural inflammation of the digestive system. It usually involves the small intestine and/or the area around the anus but can also affect the entire gastrointestinal tract anywhere from the mouth to the anus. Extra intestinal manifestations occur frequently and multiple organ systems may be affected: the skin, joints, spine, eyes, liver and bile ducts. In contrast, nasal manifestations are extremely rare and only a few cases have been reported up to date in the worldwide literature. The authors report two cases with nasal manifestations concomitant to intestinal Crohn's disease and go over the relevant literature on such an association.

Omega-3 Fatty Acids as Adjunctive Therapy in Crohns Disease

Crohns disease is an inflammatory bowel disease that can have a significant impact on the health of those afflicted. The etiology of the disease is unknown, but genetic, environmental, dietary, and immunological factors are thought to be involved. Multiple nutrients can become depleted during active disease due to inadequate intake or malabsorption. Preventing these deficiencies is paramount in the care of those suffering from Crohns disease. Often the traditional treatments (medications) have limited effectiveness and negative side effects that inhibit their use. Enteral nutrition has promising therapeutic benefits, but its use is often limited to the pediatric population due to poor patient acceptability. Omega-3 fatty acids have been investigated for their anti-inflammatory properties as an alternative to traditional care. This article reviews the etiology of Crohns disease, nutritional deficiencies, traditional treatments, and the use of omega-3 fatty acids in the prevention of Crohns recurrence. The results from clinical trials have been conflicting, but a new fish oil preparation that limits the side effects of traditional fish oil therapy shows promise as an adjunctive treatment for Crohns disease. Continued research is needed to validate these findings.