Efficacy of a Transforming Growth Factor β2 Containing Nutritional Support Formula in a Murine Model of Inflammatory Bowel 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.

Babies, Bugs, and Barriers: Dietary Modulation of Intestinal Barrier Function in Early Life

The intestinal barrier is essential in early life to prevent infection, inflammation, and food allergies. It consists of microbiota, a mucus layer, an epithelial layer, and the immune system. Microbial metabolites, the mucus, antimicrobial peptides, and secretory immunoglobulin A (sIgA) protect the intestinal mucosa against infection. The complex interplay between these functionalities of the intestinal barrier is crucial in early life by supporting homeostasis, development of the intestinal immune system, and long-term gut health. Exclusive breastfeeding is highly recommended during the first 6 months. When breastfeeding is not possible, milk-based infant formulas are the only safe alternative. Breast milk contains many bioactive components that help to establish the intestinal microbiota and influence the development of the intestinal epithelium and the immune system. Importantly, breastfeeding lowers the risk for intestinal and respiratory tract infections. Here we review all aspects of intestinal barrier function and the nutritional components that impact its functionality in early life, such as micronutrients, bioactive milk proteins, milk lipids, and human milk oligosaccharides. These components are present in breast milk and can be added to milk-based infant formulas to support gut health and immunity. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Declining Use of Corticosteroids for Crohn's Disease Has Implications for Study Recruitment: Results of a Pilot Randomized Controlled Trial

Background

Corticosteroids (CS) have been used extensively to induce remission in Crohn’s disease (CD); however, they are associated with severe side effects. We hypothesized that the administration of an exclusive enteral nutrition (EEN) formula to CS would lead to increased CD remission rates and to decreased CS-related adverse events. We proposed to undertake a pilot study comparing EEN and CS therapy to CS alone to assess decrease symptoms and inflammatory markers over 6 weeks.

Aim

The overall aim was to assess study feasibility based on recruitment rates and acceptability of treatment in arms involving EEN

Methods

The pilot study intended to recruit 100 adult patients with active CD who had been prescribed CS to induce remission as part of their care. The patients were randomized to one of three arms: (i) standard-dose CS; (ii) standard-dose CS plus EEN (Modulen 1.5 kcal); or (iii) short-course CS plus EEN.

Results

A total of 2009 CD patients attending gastroenterology clinics were screened from October 2018 to November 2019. Prednisone was prescribed to only 6.8% (27/399) of patients with active CD attending outpatient clinics. Of the remaining 372 patients with active CD, 34.8% (139/399) started or escalated immunosuppressant or biologics, 49.6% (198/399) underwent further investigation and 8.8% (35/399) were offered an alternative treatment (e.g., antibiotics, surgery or investigational agents in clinical trials). Only three patients were enrolled in the study (recruitment rate 11%; 3/27), and the study was terminated for poor recruitment.

Conclusion

The apparent decline in use of CS for treatment of CD has implications for CS use as an entry criterion for clinical trials.

Supplementation of Bovine Colostrum in Inflammatory Bowel Disease: Benefits and Contraindications

Inflammatory bowel disease (IBD) is a group of chronic relapsing disorders whose etiology has not been fully explained. Therefore, available therapeutic approaches for IBD patients are still insufficient. Current treatment strategies are targeted to immune system dysfunctions, often associated with alternations in the microbiota, which contribute to the development of chronic intestinal inflammation. Therapeutics include anti-inflammatory drugs such as aminosalicylates and corticosteroids, immunosuppressive agents, antibiotics, and biological agents such as infliximab and vedolizumab. Auxiliary therapies involve a balanced and personalized diet, healthy lifestyle, avoiding stress, as well as dietary supplements. In this review, we discuss the use of bovine colostrum (BC) as a therapeutic agent, including its advantages and contraindications. We summarize our knowledge on well-researched BC constituents and their effects on the gastrointestinal tract as evidenced in in vitro and in vivo studies.

Breast Milk: A Source of Functional Compounds with Potential Application in Nutrition and Therapy

Breast milk is an unbeatable food that covers all the nutritional requirements of an infant in its different stages of growth up to six months after birth. In addition, breastfeeding benefits both maternal and child health. Increasing knowledge has been acquired regarding the composition of breast milk. Epidemiological studies and epigenetics allow us to understand the possible lifelong effects of breastfeeding. In this review we have compiled some of the components with clear functional activity that are present in human milk and the processes through which they promote infant development and maturation as well as modulate immunity. Milk fat globule membrane, proteins, oligosaccharides, growth factors, milk exosomes, or microorganisms are functional components to use in infant formulas, any other food products, nutritional supplements, nutraceuticals, or even for the development of new clinical therapies. The clinical evaluation of these compounds and their commercial exploitation are limited by the difficulty of isolating and producing them on an adequate scale. In this work we focus on the compounds produced using milk components from other species such as bovine, transgenic cattle capable of expressing components of human breast milk or microbial culture engineering.

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.

Effect of Oral Nutrition Supplements and TGF-β2 on Nutrition and Inflammatory Patterns in Patients With Active Crohn's Disease

BACKGROUND

Crohn's disease (CD) is often associated with nutrition disorders. Many nutrition therapeutic alternatives have been studied. Nevertheless, the actual role of nutrition therapy is still controversial. The objective of this study was to assess the effects of nutrition supplementation with and without transforming growth factor-beta 2 (TGF-β2) on inflammatory, endoscopic, histopathologic, and nutrition parameters in active CD.

MATERIALS AND METHODS

Thirty-eight patients were allocated into 3 groups: group 1 (patients who received only nutrition orientation), group 2 (nutrition orientation and a normoproteic, normocaloric nutrition supplement), and group 3 (nutrition orientation and the nutritional supplement with TGF-β2). Clinical and nutrition evaluation, C-reactive protein (CRP) levels, and assessment of endoscopic and histologic parameters in the intestinal mucosa were performed before and after nutrition intervention.

RESULTS

The mean follow-up period was 3 months. In the beginning of the study, groups were homogeneous regarding age, gender, CD behavior and localization, and medication in use. In the end of the study, the Clinical Disease Activity Index score was reduced in groups 2 and 3; in group 3, a reduction in CRP levels and an improvement in histologic findings were observed. Among patients who received nutritional supplement, some anthropometric patterns were improved.

CONCLUSION

The results of the study indicate that nutritional supplementation improved nutrition and inflammatory patterns in patients with active CD. However, only patients receiving TGF-β2-enriched formula showed improvement in histologic parameters and significant reduction in CRP levels.

Multiplex Cytokine Analysis of Aqueous Humor in Juvenile Idiopathic Arthritis-Associated Anterior Uveitis With or Without Secondary Glaucoma

Patients with juvenile idiopathic arthritis often develop chronic anterior uveitis (JIAU). JIAU patients possess a particularly high risk for developing secondary glaucoma when inflammatory inactivity has been achieved. By using multiplex bead assay analysis, we assessed levels of pro- and anti-inflammatory cytokines, chemokines, or metalloproteinases in the aqueous humor (AH) of patients with clinically inactive JIAU with (JIAUwG) or without secondary glaucoma (JIAUwoG), or from patients with senile cataract as controls. Laser-flare photometry analysis prior to surgery showed no significant differences between JIAUwG or JIAUwoG. Compared with the control group, levels of interleukin-8, matrix metalloproteinase-2, -3, -9, serum amyloid A (SAA), transforming growth factor beta-1, -2, -3 (TGFβ-1, -2, -3), and tumor necrosis factor-alpha in the AH were significantly higher in patients with clinically inactive JIAUwG or JIAUwoG. Samples from JIAwoG patients displayed significantly higher levels of SAA (P < 0.0116) than JIAUwG patients. JIAUwG patients showed an increased level of TGFβ-2 in AH samples compared with JIAUwoG (P < 0.0009). These molecules may contribute to the clinical development of glaucoma in patients with JIAU.

Cytokines in milk and the role of TGF-beta

Cytokines are required for normal growth and development of the mammary gland and TGF-β prominently represents an established effector of apoptosis, e.g., during involution of the mammary gland. By the control of intracellular signaling pathways, including JAK/STAT, MAPK, PI-3K, and NF-κB, cytokines efficiently regulate cell proliferation and inflammation in the breast. Therefore, cytokines are discussed also in a context of malignant mammary growth. As a group of tissue hormones produced by somatic cells or by cells from the immune system, cytokines are defined by their immunomodulatory potential. Over the past 40 years, multiple cytokines were identified in colostrum and milk. Importantly, cytokines derived from mammary secretions after birth are required for maturation of the immune system in the developing gastrointestinal tract from the suckling. Moreover, recent studies have further assessed the particular interactions between probiotic bacterial strains and cytokines. In light of the increasing prevalence of inflammatory diseases of the gastrointestinal system, the effects of probiotic microorganisms during milk fermentation may have immunotherapeutic potential in the future.

Nutrients, Infectious and Inflammatory Diseases

A balanced diet with sufficient essential nutritional elements is critical for maintaining a healthy body.[...].

Morphogenesis and maturation of the embryonic and postnatal intestine

The intestine is a vital organ responsible for nutrient absorption, bile and waste excretion, and a major site of host immunity. In order to keep up with daily demands, the intestine has evolved a mechanism to expand the absorptive surface area by undergoing a morphogenetic process to generate finger-like units called villi. These villi house specialized cell types critical for both absorbing nutrients from food, and for protecting the host from commensal and pathogenic microbes present in the adult gut. In this review, we will discuss mechanisms that coordinate intestinal development, growth, and maturation of the small intestine, starting from the formation of the early gut tube, through villus morphogenesis and into early postnatal life when the intestine must adapt to the acquisition of nutrients through food intake, and to interactions with microbes.

Immunopathogenesis of Crohn's Disease

This review highlights the huge advances made in the understanding of Crohn's disease in the last 15 years. The pathogenic immune response in the gut wall is a highly polarised T helper cell type 1 response, probably directed against antigens of the commensal flora. There is marked over-expression of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and increased production of matrix degrading enzymes by fibroblasts and macrophages, which are probably responsible for ulceration and fistula formation. Crohn's disease runs in families and the susceptibility genes identified so far are associated with innate recognition of microbial products (Nod2) or epithelial barrier function (OCTN cation transporter genes and DLG5). Endogenous healing pathways mediated by transforming growth factor (TGF)-beta1 are inhibited because mucosal inflammatory cells express Smad7, the endogenous intracellular inhibitor of TGF-beta signalling. This makes it unlikely that enteral feeds containing TFG-beta are therapeutic by means of direct anti-inflammatory effects, however TGF-beta may still be involved because it is a well known epithelial motogen and may promote mucosal healing, in synergy with changes in mucosal bacterial populations as a result of the change in the diet.

Co-expression of the protease furin in Nicotiana benthamiana leads to efficient processing of latent transforming growth factor-β1 into a biologically active protein

Transforming growth factor beta (TGF-β) is a signalling molecule that plays a key role in developmental and immunological processes in mammals. Three TGF-β isoforms exist in humans, and each isoform has unique therapeutic potential. Plants offer a platform for the production of recombinant proteins, which is cheap and easy to scale up and has a low risk of contamination with human pathogens. TGF-β3 has been produced in plants before using a chloroplast expression system. However, this strategy requires chemical refolding to obtain a biologically active protein. In this study, we investigated the possibility to transiently express active human TGF-β1 in Nicotiana benthamiana plants. We successfully expressed mature TGF-β1 in the absence of the latency-associated peptide (LAP) using different strategies, but the obtained proteins were inactive. Upon expression of LAP-TGF-β1, we were able to show that processing of the latent complex by a furin-like protease does not occur in planta. The use of a chitinase signal peptide enhanced the expression and secretion of LAP-TGF-β1, and co-expression of human furin enabled the proteolytic processing of latent TGF-β1. Engineering the plant post-translational machinery by co-expressing human furin also enhanced the accumulation of biologically active TGF-β1. This engineering step is quite remarkable, as furin requires multiple processing steps and correct localization within the secretory pathway to become active. Our data demonstrate that plants can be a suitable platform for the production of complex proteins that rely on specific proteolytic processing.

XP-828L in the Treatment of Mild to Moderate Psoriasis: Randomized, Double-Blind, Placebo-Controlled Study

Background:

XP-828L, a protein extract obtained from sweet whey, has demonstrated potential benefit for the treatment of mild to moderate psoriasis in an open-label study.

Objective:

To study in a randomized, double-blind, placebo-controlled study the safety and efficacy of XP-828L in the treatment of mild to moderate psoriasis.

Design:

XP-828L 5 g/d (group A, n = 42) or placebo (group B, n = 42) was given orally for 56 days followed by XP-828L 5 g/d in group A and by XP-828L 10 g/d in group B for an additional 56 days.

Results:

Patients receiving XP-828L 5 g/d for 56 days had an improved Physician's Global Assessment (PGA) score compared with patients under placebo ( p < .05). Considering the data of group A only, the PGA score improved from day 1 to day 56 ( p < .01); the Psoriasis Area and Severity Index score improved as well, but to a lesser extent ( p < .05).

Conclusion:

Oral administration of 5 g/d XP-828L compared with a placebo significantly improved the PGA score of patients with mild to moderate psoriasis.

Breastfed at Tiffany's

The importance of breast milk for the growing infant is undisputed; breastfeeding decreases infantile mortality by tenfold and decreases the incidence of infectious diseases. Despite its recognized benefits, the structural richness of breast milk has also impeded the characterization of the multiple effects of milk components on infant physiology. However, the important roles of some components of breast milk are beginning to be dissected. For instance, molecules such as immunoglobulin A (IgA) and milk oligosaccharides protect from gastrointestinal infections and influence the development of the gut microbiota. Deciphering the complex composition of breast milk brings to light multifaceted contributions that combine to make breast milk the ultimate personalized medicine.

Clinical applications of bioactive milk components

Milk represents a unique resource for translational medicine: It contains a rich pool of biologically active molecules with demonstrated clinical benefits. The ongoing characterization of the mechanistic process through which milk components promote development and immunity has revealed numerous milk-derived compounds with potential applications as clinical therapies in infectious and inflammatory disease, cancer, and other conditions. Lactoferrin is an effective antimicrobial and antiviral agent in high-risk patient populations and a potentially potent adjuvant to chemotherapy in lung cancer. Enteric nutrition formulas supplemented with transforming growth factor β, a milk cytokine, have been shown to promote remission in pediatric Crohn's disease. A number of milk glycans, including human milk oligosaccharides, show promise in preclinical studies as antimicrobial and anti-inflammatory agents. While active preclinical investigations of human milk may soon result in large-scale production of human milk molecules, bovine milk components in many instances represent a practical source of bioactive milk compounds for use in clinical trials. This review summarizes current efforts to translate the compounds derived from human and bovine milk into effective clinical therapies. These efforts suggest a common pathway for the translation of milk-derived compounds into clinical applications.

Early microbial contact, the breast milk microbiome and child health

The significance of contact with microbes in early life for subsequent health has been the subject of intense research during the last 2 decades. Disturbances in the establishment of the indigenous intestinal microbiome caused by cesarean section delivery or antibiotic exposure in early life have been linked to the risk of immune-mediated and inflammatory conditions such as atopic disorders, inflammatory bowel disease and obesity later in life. Distinct microbial populations have recently been discovered at maternal sites including the amniotic cavity and breast milk, as well as meconium, which have previously been thought to be sterile. Our understanding of the impact of fetal microbial contact on health outcomes is still rudimentary. Breast milk is known to modulate immune and metabolic programming. The breast milk microbiome is hypothesized to guide infant gut colonization and is affected by maternal health status and mode of delivery. Immunomodulatory factors in breast milk interact with the maternal and infant gut microbiome and may mediate some of the health benefits associated with breastfeeding. The intimate connection between the mother and the fetus or the infant is a potential target for microbial therapeutic interventions aiming to support healthy microbial contact and protect against disease.

Evaluation of transforming growth factor-β2 for radiation-induced diarrhea after pelvic radiotherapy

AIMS AND BACKGROUND

Radiotherapy (RT) plays a central role in the management of cancers located in the abdomen and pelvis. However, radiation-induced toxicity remains a major concern for patients receiving RT to the abdominopelvic region. In this context, our study aims to evaluate the use of transforming growth factor (TGF)-β2-enriched formula for amelioration of radiation-induced diarrhea for patients undergoing pelvic RT.

METHODS AND STUDY DESIGN

Between September 2013 and September 2014, 86 malnourished patients undergoing RT for pelvic cancers who received oral nutritional supplementation with or without TGF-β2-enriched formula were assessed retrospectively in 3 groups. Oral diphenoxylate-atropine tablets were used at onset of diarrhea in all groups. Kruskal-Wallis and chi-square tests were used in the comparison of continuous and categorical variables, respectively.

RESULTS

Patients receiving nutritional supplemention with TGF-β2-enriched formula (groups I and II) experienced a significantly lower median number of diarrhea episodes compared to patients receiving nutritional supplementation with other products (group III), which was statistically significant (p&lt;0.05). Also, number of patients experiencing grade 2 and grade 3 diarrhea was significantly lower in groups I and II compared to group III (p&lt;0.05).

CONCLUSIONS

Nutritional supplemention with TGF-β2-enriched formula offers amelioration of radiation-induced diarrhea for patients receiving pelvic RT. Since this is the first study assessing the use of nutritional supplementation with TGF-β2-enriched formula for patients undergoing pelvic RT, future prospective studies are needed to confirm the results.

Diet in the pathogenesis and treatment of inflammatory bowel diseases

Some of the most common symptoms of the inflammatory bowel diseases (IBD, which include ulcerative colitis and Crohn's disease) are abdominal pain, diarrhea, and weight loss. It is therefore not surprising that clinicians and patients have wondered whether dietary patterns influence the onset or course of IBD. The question of what to eat is among the most commonly asked by patients, and among the most difficult to answer for clinicians. There are substantial variations in dietary behaviors of patients and recommendations for them, although clinicians do not routinely endorse specific diets for patients with IBD. Dietary clinical trials have been limited by their inability to include a placebo control, contamination of study groups, and inclusion of patients receiving medical therapies. Additional challenges include accuracy of information on dietary intake, complex interactions between foods consumed, and differences in food metabolism among individuals. We review the roles of diet in the etiology and management of IBD based on plausible mechanisms and clinical evidence. Researchers have learned much about the effects of diet on the mucosal immune system, epithelial function, and the intestinal microbiome; these findings could have significant practical implications. Controlled studies of patients receiving enteral nutrition and observations made from patients on exclusion diets have shown that components of whole foods can have deleterious effects for patients with IBD. Additionally, studies in animal models suggested that certain nutrients can reduce intestinal inflammation. In the future, engineered diets that restrict deleterious components but supplement beneficial nutrients could be used to modify the luminal intestinal environment of patients with IBD; these might be used alone or in combination with immunosuppressive agents, or as salvage therapy for patients who do not respond or lose responsiveness to medical therapies. Stricter diets might be required to induce remission, and more sustainable exclusion diets could be used to maintain long-term remission.

Protective effects of transforming growth factor β2 in intestinal epithelial cells by regulation of proteins associated with stress and endotoxin responses

Transforming growth factor (TGF)-β2 is an important anti-inflammatory protein in milk and colostrum. TGF-β2 supplementation appears to reduce gut inflammatory diseases in early life, such as necrotizing enterocolitis (NEC) in young mice. However, the molecular mechanisms by which TGF-β2 protects immature intestinal epithelial cells (IECs) remain to be more clearly elucidated before interventions in infants can be considered. Porcine IECs PsIc1 were treated with TGF-β2 and/or lipopolysaccharide (LPS), and changes in the cellular proteome were subsequently analyzed using two-dimensional gel electrophoresis-MS and LC-MS-based proteomics. TGF-β2 alone induced the differential expression of 13 proteins and the majority of the identified proteins were associated with stress responses, TGF-β and Toll-like receptor 4 signaling cascades. In particular, a series of heat shock proteins had similar differential trends as previously shown in the intestine of NEC-resistant preterm pigs and young mice. Furthermore, LC-MS-based proteomics and Western blot analyses revealed 20 differentially expressed proteins following treatment with TGF-β2 in LPS-challenged IECs. Thirteen of these proteins were associated with stress response pathways, among which five proteins were altered by LPS and restored by TGF-β2, whereas six were differentially expressed only by TGF-β2 in LPS-challenged IECs. Based on previously reported biological functions, these patterns indicate the anti-stress and anti-inflammatory effects of TGF-β2 in IECs. We conclude that TGF-β2 of dietary or endogenous origin may regulate the IEC responses against LPS stimuli, thereby supporting cellular homeostasis and innate immunity in response to bacterial colonization, and the first enteral feeding in early life.

Maternal breast milk transforming growth factor-beta and feeding intolerance in preterm infants

BACKGROUND

Feeding intolerance (FI) occurs commonly in the neonatal intensive care unit. Breast milk contains a large pool of transforming growth factor-beta (TGF-β). Few studies describe TGF-β levels in preterm milk, and the relationship to FI remains unexplored. We measured TGF-β levels in preterm breast milk to investigate a correlation with FI in preterm infants.

METHODS

Prospective observational trial of 100 mother-infant pairs, enrolling infants born below 32 wk gestation and less than 1,500 g, and mothers who planned to provide breast milk. TGF-β levels were measured using enzyme-linked immunosorbent assay. Infant charts were reviewed for outcomes.

RESULTS

TGF-β declined postnatally, most elevated in colostrum (P < 0.01). TGF-β2 levels were higher than TGF-β1 at all time points (P < 0.01). Colostrum TGF-β levels correlated inversely with birth weight (P < 0.01) and gestational age (P < 0.05). One-week TGF-β2 levels were reduced in growth-restricted infants with FI (P < 0.01). Of infants with necrotizing enterocolitis (NEC), TGF-β2 levels appeared to be low, but small sample size precluded meaningful statistical comparisons.

CONCLUSION

TGF-β levels decline temporally in preterm milk. TGF-β1 colostrum levels correlate inversely with birth weight and gestational age. TGF-β2 may play a role in FI in growth-restricted infants. The relationship of TGF-β2 and NEC merits future investigation.

Whey protein processing influences formula-induced gut maturation in preterm pigs

Immaturity of the gut predisposes preterm infants to nutritional challenges potentially leading to clinical complications such as necrotizing enterocolitis. Feeding milk formulas is associated with greater risk than fresh colostrum or milk, probably due to loss of bioactive proteins (e.g., immunoglobulins, lactoferrin, insulin-like growth factor, transforming growth factor-β) during industrial processing (e.g., pasteurization, filtration, spray-drying). We hypothesized that the processing method for whey protein concentrate (WPC) would affect gut maturation in formula-fed preterm pigs used as a model for preterm infants. Fifty-five caesarean-delivered preterm pigs were distributed into 4 groups given 1 of 4 isoenergetic diets: formula containing conventional WPC (filtration, multi-pasteurization, standard spray-drying) (CF); formula containing gently treated WPC (reduced filtration and pasteurization, gentle spray-drying) (GF); formula containing minimally treated WPC (rennet precipitation, reduced filtration, heat treatment <40°C, freeze-drying) (MF); and bovine colostrum (used as a positive reference group) (BC). Relative to CF, GF, and MF pigs, BC pigs had greater villus heights, lactose digestion, and absorption and lower gut permeability (P < 0.05). MF and BC pigs had greater plasma citrulline concentrations than CF and GF pigs and intestinal interleukin-8 was lower in BC pigs than in the other groups (P < 0.05). MF pigs had lower concentrations of intestinal claudin-4, cleaved caspase-3, and phosphorylated c-Jun than CF pigs (P < 0.05). The conventional and gently treated WPCs had similar efficacy in stimulating proliferation of porcine intestinal epithelial cells. We conclude that processing of WPC affects intestinal structure, function, and integrity when included in formulas for preterm pigs. Optimization of WPC processing technology may be important to preserve the bioactivity and nutritional value of formulas for sensitive newborns.

Inflammatory bowel disease therapies and gut function in a colitis mouse model

BACKGROUND

Exclusive enteral nutrition (EEN) is a well-established approach to the management of Crohn's disease. Aim. To determine effects of EEN upon inflammation and gut barrier function in a colitis mouse model.

METHODS

Interleukin-10-deficient mice (IL-10(-/-)) were inoculated with Helicobacter trogontum and then treated with EEN, metronidazole, hydrocortisone, or EEN and metronidazole combination. Blood and tissue were collected at 2 and 4 weeks with histology, mucosal integrity, tight junction integrity, inflammation, and H. trogontum load evaluated.

RESULTS

H. trogontum induced colitis in IL-10(-/-) mice with histological changes in the cecum and colon. Elevated mucosal IL-8 mRNA in infected mice was associated with intestinal barrier dysfunction indicated by decreased transepithelial electrical resistance and mRNA of tight junction proteins and increased short-circuit current, myosin light chain kinase mRNA, paracellular permeability, and tumor necrosis factor- α and myeloperoxidase plasma levels (P < 0.01 for all comparisons). EEN and metronidazole, but not hydrocortisone, treatments restored barrier function, maintained gut barrier integrity, and reversed inflammatory changes along with reduction of H. trogontum load (versus infected controls P < 0.05).

CONCLUSION

H. trogontum infection in IL-10(-/-) mice induced typhlocolitis with intestinal barrier dysfunction. EEN and metronidazole, but not hydrocortisone, modulate barrier dysfunction and reversal of inflammatory changes.

Green Tea Polyphenols and Sulfasalazine have Parallel Anti-Inflammatory Properties in Colitis Models

Background: There is no cure for autoimmune chronic inflammatory bowel disease (IBD). IBD patients commonly use complementary and alternative medications of which the safety, efficacy, and interaction with standard-of-care therapies are not fully known. Thus the consequences can become life-threatening. Sulfasalazine commonly used in IBD, potentially has severe adverse effects, including infertility, pulmonary fibrosis, lack of response, and ultimately patients may require intestinal resection. We hypothesized that green tea polyphenols (GrTP, EGCG) and sulfasalazine have similar anti-inflammatory properties.

Methods: BALB/c mice received Dextran sodium sulfate (DSS) to induce colitis (ulcerative colitis model). Exposure of IL-10 deficient mice (BALB/c-background) to normal microbiota provoked enterocolitis (mimics Crohn’s disease). Animals were treated with agents incorporated into daily diets. Control animals received sham treatment.

Results: DSS-treated animals developed severe bloody diarrhea and colitis (score 0–4, 3.2 ± 0.27). IL-10 deficient mice developed severe enterocolitis as manifested by diarrhea, rectal prolapse, and colonic lesions. Animals tolerated regimens (GrTP, EGCG, sulfasalazine) with no major side effects, and further developed less severe colitis. IL-10 deficient animals became moribund on high dose, while tolerated low and Mid doses with significant improved symptoms of enterocolitis. GrTP, EGCG, and sulfasalazine significantly ameliorated colonic damage and histological scores in treated animals in a similar manner (GrTP vs. DSS p < 0.05; EGCG, sulfasalazine vs. DSS p < 0.01). The inflammatory markers TNFα (3-fold), IL-6 (14-fold), and serum amyloid A (40-fold) increased in colitic animals and significantly decreased with treatment regiments. In contrast, circulatory leptin levels decreased in colitic animals (twofold). EGCG additionally reduced leptin levels (p < 0.01) while GrTP and sulfasalazine had no effect on leptin levels (p < 0.05). Hepatic and colonic antioxidants were significantly depleted in colitic animals and treatment regiments significantly restored antioxidants levels.

Conclusion: GrTP and EGCG improved antioxidants levels and attenuated severity of colitis analogous to sulfasalazine. Future studies will reveal whether polyphenols can become an alternative/additive therapy for IBD therapy in humans.

TGF-β affects enterocyte turnover in correlation with TGF-β receptor expression after massive small bowel resection

OBJECTIVES

In the present study, we evaluated the effect of transforming growth factor-beta 2 (TGF-β2)-enriched diet on enterocyte turnover and correlated it with TGF-β2 receptor expression along the villus-crypt axis in a rat model of short bowel syndrome (SBS).

METHODS

CaCo-2 cells were incubated with increasing concentrations of TGF-β2. Alamar Blue reduction test was used for investigation of cell viability and evaluation of cell apoptosis was assessed by flow cytometry. Male rats were divided into 4 groups: Sham rats underwent bowel transection, Sham TGF-β rats were treated with diet enriched with TGF-β2, SBS rats underwent a 75% bowel resection, and SBS TGF-β rats were fed a diet enriched with TGF-β2 after bowel resection. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined at sacrifice. TGF-β2r expression in villus tips, lateral villi and crypts was assessed by immunohistochemistry. The effect of TGF-β2 on enterocyte turnover for each compartment was evaluated in correlation with TGF-β2r expression.

RESULTS

Incubation of CaCo-2 cells with TGF-β2 resulted in a significant decrease in cell viability and increased cell apoptosis. TGF-β2r expression in crypts increased in SBS rats (vs sham) and was accompanied by decreased cell proliferation and increased cell apoptosis following TGF-β2 administration. A significant decrease in TGF-β2r expression at villous tips in SBS rats was accompanied by a decreased cell apoptosis in this compartment following exposure to TGF-β2-enriched diet.

CONCLUSIONS

In a rat model of SBS, the inhibiting effect of TGF-β2 on enterocyte turnover correlates with TGF-β2 receptor expression along the villus-crypt axis.

Pegylated arginine deiminase downregulates colitis in murine models

Arginine deiminase (ADI), an arginine-metabolizing enzyme involved in cell signaling, is dysregulated in multiple inflammatory diseases and cancers. We hypothesized that pegylated ADI (ADI-PEG) provide protection against colitis. Methods. Dextran sodium sulfate colitis was induced in IL-10-deficient and BALB/c (WT) mice. ADI-PEG was administered i.p., and inflammatory mediators and pathology were evaluated. Results. Acute colitis in mice was manifested by increases in inflammatory biomarkers, such as serum amyloid A (SAA, P < 0.001), IL-12 p40, and disease index (3-Fold). In contrast, ADI-PEG significantly decreased clinical disease index, SAA levels, and inflammatory cytokines in blood as well as in colonic explants. Animals developed moderate (2.2 ± 0.3 WT) to severe (3.6 ± 0.5 IL-10 deficient) colonic pathology; and ADI-PEG treatment significantly improved the severity of colitis (P < 0.05). Marked infiltration of CD68⁺ macrophages and iNOS expression were detected in colonic submucosa in colitic animals but not detected in ADI-PEG-treated animals. Conclusion. ADI-PEG attenuated inflammatory responses by suppression of macrophage infiltration and iNOS expression in colitic animals. ADI-PEG can serve as a potential therapeutic value in IBD.

Kiwifruit extracts inhibit cytokine production by lipopolysaccharide-activated macrophages, and intestinal epithelial cells isolated from IL10 gene deficient mice

Inflammatory bowel disease (IBD) is a chronic, inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. This study examined the effects of aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (Actinidia deliciosa) using in vitro models of IBD. These models comprised primary macrophages and intestinal epithelial cells isolated from C57BL/5J and interleukin-10 gene deficient (Il10(-/-)) mice and RAW 264.7, a murine macrophage-like cell line. All four kiwifruit extracts reduced the activation of these models after lipopolysaccharide stimulation, decreasing nitric oxide and cytokine secretion by both Il10(-/-) and wild-type cells. The ethyl acetate extracts exhibited the highest anti-inflammatory activity, with almost complete suppression of lipopolysaccharide-stimulated macrophage activation. These results suggest that kiwifruit extracts have significant anti-inflammatory activity relevant to IBD. We suggest that the Il10(-/-) mouse is a suitable model for further study of these compounds.

Nutritional supplementation with transforming growth factor-beta inhibits intestinal adaptation after massive small bowel resection in a rat

INTRODUCTION

Transforming growth factor beta (TGF-β) has been shown to affect epithelial cell differentiation and proliferation through epithelial-mesenchymal and epithelial-immune cell interaction. In the present study, we evaluated the effect of TGF-β2-enriched polymeric diet (Modulen) on enterocyte turnover in a rat model of short bowel syndrome (SBS).

METHODS

Male rats were divided into four groups: Sham rats and Sham-TGF-β rats underwent bowel transection, and were treated with TGF-β from the 4th postoperative day, SBS rats underwent a 75% bowel resection, and SBS-TGF-β rats underwent bowel resection and were treated with TGF-β-enriched diet similar to Group B. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined on day 15. Real-time PCR was used to determine Bax and Bcl-2 mRNA expression.

RESULTS

Treatment of SBS animals with TGF-β2 supplemented diet led to a significant decrease (vs. SBS rats) in bowel weight in ileum (18%, P < 0.05), mucosal DNA content in jejunum (threefold decrease, P < 0.05) and ileum (2.5-fold decrease, P < 0.05), and mucosal protein in jejunum (twofold decrease, P < 0.05) compared to SBS-untreated animals (Group B). Treatment with TGF-β resulted in a mild decrease in enterocyte proliferation in jejunum (25%, P < 0.05) and ileum (18%, P < 0.05). A decreased cell apoptosis in the SBS-TGF-β group was accompanied by a decreased Bax and increased Bcl-2 mRNA expression.

CONCLUSIONS

In a rat model of SBS, dietary TGF-β inhibits intestinal adaptation. Decreased enterocyte proliferation is responsible for this effect.

GSEA-SNP identifies genes associated with Johne's disease in cattle

SNP-based gene-set enrichment analysis from single nucleotide polymorphisms, or GSEA-SNP, is a tool to identify candidate genes based on enrichment analysis of sets of genes rather than single SNP associations. The objective of this study was to identify modest-effect genes associated with Mycobacterium avium subsp. paratuberculosis (Map) tissue infection or fecal shedding using GSEA-SNP applied to KEGG pathways or Gene Ontology (GO) gene sets. The Illumina Bovine SNP50 BeadChip was used to genotype 209 Holstein cows for the GSEA-SNP analyses. For each of 13,744 annotated genes genome-wide located within 50 kb of a Bovine SNP50 SNP, the single SNP with the highest Cochran-Armitage Max statistic was used as a proxy statistic for that gene's strength of affiliation with Map. Gene-set enrichment was tested using a weighted Kolmogorov-Smirnov-like running sum statistic with data permutation to adjust for multiple testing. For tissue infection and fecal shedding, no gene sets in KEGG pathways or in GO sets for molecular function or cellular component were enriched for signal. The GO biological process gene set for positive regulation of cell motion (GO:0051272, q = 0.039, 5/11 genes contributing to the core enrichment) was enriched for Map tissue infection, while no GO biological process gene sets were enriched for fecal shedding. GSEA-SNP complements traditional SNP association approaches to identify genes of modest effects as well as genes with larger effects as demonstrated by the identification of one locus that we previously found to be associated with Map tissue infection using a SNP-by-SNP genome-wide association study.

GREEN TEA POLYPHENOLS MEDIATED APOPTOSIS IN INTESTINAL EPITHELIAL CELLS BY A FADD-DEPENDENT PATHWAY

Colorectal cancer is the most common malignant complication in patients with chronic inflammatory bowel disease (IBD). In addition, these patients are at risk for developing painful complications during chemotherapy due to cytotoxic effects of drugs currently in use. Past studies have suggested a protective effect of tea consumption on gastrointestinal (GI) malignancies. Green tea polyphenols (GrTP) inhibited carcinogen-induced GI tumors in rodents and induced apoptosis in various carcinoma cell lines. We hypothesized that GrTP and its polyphenolic compounds regulate apoptosis in the intestinal epithelia. In this study, the effects of GrTP and its polyphenolics on apoptosis was evaluated in intestinal epithelial, IEC-6, cells grown to 85% confluency. GrTP (400-800 mg/ml) induced DNA fragmentation in a dose dependent fashion. Higher concentrations (>800 mg/ml) induced a mixed apoptosis and cytolysis. Epithelial cells exposed to GrTP and a major polyphenol, EGCG, but not EGC or EC, increased caspase activities in a time and dose dependent manner. The caspase inhibitors rescued cells from GrTP and EGCG-induced cell death. Concomitantly, GrTP resulted in activation of fatty acid synthase (Fas)-associated protein with death domain (FADD) and recruitment to Fas/CD95 domain 30 minutes following treatment. While GrTP also blocked NF-κB activation, an NFκ-B inhibitor (MG132) only promoted cytolysis. In conclusion, these data demonstrated GrTP and EGCG induced apoptosis in intestinal epithelia mediated by caspase-8 through a FADD dependent pathway. Future investigation may warrant preventive as well as therapeutic strategies for GrTP in GI malignancy.

Post-weaning effects of milk and milk components on the intestinal mucosa in inflammation

Many milk-derived components have immunomodulatory and anti-inflammatory properties, and some of these reduce intestinal inflammation when orally administered to animal models of colitis. However, the potential for ruminant milk or milk components to benefit people with intestinal inflammatory disorders (such as Inflammatory Bowel Disease) has not been well-researched. This review describes published research into mechanisms by which ruminant milk and its components may have beneficial effects when consumed by people who have intestinal inflammation.

Nutrition intervention: a strategy against systemic inflammatory syndrome

BACKGROUND

Sepsis and septic shock syndrome are the leading causes of death in critically ill patients. Lipopolysaccharide (LPS) released by the colonic microorganisms may translocate across a compromised lumen, leading to upregulated reactive oxidative stress, inflammation, and sepsis. The authors examined an enteral formula high in cysteine (antioxidant precursor), omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and prebiotic fructooligosaccharides (FOS) against systemic inflammatory syndrome.

METHODS

Rats were allocated to (1) standard soy-based diet high in cysteine and crude fiber and devoid of EPA-DHA (CHOW); (2) whey-peptide-based liquid diet high in cysteine, EPA-DHA, and FOS (CYSPUFA); or (3) casein-based liquid isonitrogenous diet, low in cysteine and devoid of EPA-DHA-FOS (CASN). Liquid diets provided 25% and CHOW, 23% of calories as protein. After 6 days on diets, rats received an intraperitoneal injection of LPS or saline. Animals gained weight on their respective diets and lost weight after LPS administration. The CYSPUFA group lost considerably less weight (vs CASN or CHOW, P < .05). Inflammatory cytokines significantly increased by 4 hours and subsided 18 hours after assault. The CASN group showed elevated liver enzyme alanine aminotransferase release from damaged hepatocytes and developed severe hepatic pathology with low hematocrit. The CHOW group developed more severe hepatic lesions compared with those on liquid diets. Concentration of liver enzyme and pathology were improved in rats receiving CYSPUFA.

CONCLUSIONS

Data indicate that CYSPUFA, a diet rich in EPA-DHA-FOS, protects against LPS-induced systemic inflammatory responses and warrants clinical studies in critically ill patients.

Exogenous transforming growth factor beta1 replacement and fertility in male Tgfb1 null mutant mice

Analysis of Tgfb1 null mutant mice has demonstrated that the cytokine transforming growth factor β1 (TGFB1) has essential non-redundant roles in fertility. The present study attempted to alleviate the infertility phenotype of Tgfb1 null mutant male mice by administration of exogenous TGFB1, either orally by colostrum feeding or subcutaneously by delivery of recombinant human latent TGFB1 (rhLTGFB1) via osmotic mini-pumps. Bovine colostrum and fresh unpasteurised bovine milk were found to be rich sources of TGFB1 and TGFB2; however, feeding Tgfb1 null mutant mice colostrum for 2 days failed to raise serum levels of TGFB1. Administration of rhLTGFB1 (~150 μg in total) over 14 days to Tgfb1 null mutant mice resulted in detectable TGFB1 in serum; however, mean levels remained 10-fold less than in Tgfb1 heterozygous mice. After 7 days and 14 days of rhLTGFB1 administration, serum testosterone, spontaneous non-contact erections and mating behaviour were assessed. Despite the increased serum TGFB1, administration of rhLTGFB1 to Tgfb1 null mutant mice failed to improve these fertility parameters. It is concluded that sustained restoration of circulating latent TGFB1 to levels approaching the normal physiological range does not rescue the infertility phenotype caused by TGFB1 deficiency. Reproductive function in male Tgfb1 null mutant mice may not respond to systemic TGFB1 supplementation due to a requirement for local sources of TGFB1 at the site of action in the reproductive tract, or perturbed development during the neonatal period or puberty such that adult reproductive function is permanently impaired.

Serum biomarkers in a mouse model of bacterial-induced inflammatory bowel disease

BACKGROUND

The diagnosis and classification of inflammatory bowel disease (IBD) require both clinical and histopathologic data. Serum biomarkers would be of considerable benefit to noninvasively monitor the progression of disease, assess effectiveness of therapies, and assist in understanding disease pathogenesis. Currently, there are limited noninvasive biomarkers for monitoring disease progression in animal IBD models, which are used extensively to develop new therapies and to understand IBD pathogenesis.

METHODS

Serum biomarkers of early and late IBD were identified using multianalyte profiling in mdr1a(-/-) mice with IBD triggered by infection with Helicobacter bilis. The correlation of changes in these biomarkers with histopathology scores and clinical signs in the presence and in the absence of antibiotic treatment was determined.

RESULTS

Serum levels of interleukin (IL)-11, IL-17, 10-kDa interferon-gamma-inducible protein (IP-10), lymphotactin, monocyte chemoattractant protein (MCP)-1, and vascular cell adhesion molecule (VCAM)-1 were elevated early in IBD. In late, more severe IBD, serum levels of IL-11, IP-10, haptoglobin, matrix metalloproteinase-9, macrophage inflammatory protein (MIP)-1gamma, fibrinogen, immunoglobulin A, MIP-3 beta (beta), VCAM-1, apolipoprotein (Apo) A1, and IL-18 were elevated. All late serum biomarkers except Apo A1 correlated with histopathology scores. Antibiotic treatment improved clinical signs of IBD and decreased mean serum values of many of the biomarkers. For all biomarkers, the individual pathology scores correlated significantly with individual serum analyte levels after treatment.

CONCLUSIONS

Serum analyte measurement is a useful, noninvasive method for monitoring disease in a mouse model of bacterial-induced IBD.

Application of prodrugs to inflammatory diseases of the gut

Oral delivery is the most common and preferred route of drug administration although the digestive tract exhibits several obstacles to drug delivery including motility and intraluminal pH profiles. The gut milieu represents the largest mucosal surface exposed to microorganisms with 10^10-12 colony forming bacteria/g of colonic content. Approximately, one third of fecal dry matter is made of bacteria/ bacterial components. Indeed, the normal gut microbiota is responsible for healthy digestion of dietary fibers (polysaccharides) and fermentation of short chain fatty acids such as acetate and butyrate that provide carbon sources (fuel) for these bacteria. Inflammatory bowel disease (IBD) results in breakage of the mucosal barrier, an altered microbiota and dysregulated gut immunity. Prodrugs that are chemically constructed to target colonic release or are degraded specifically by colonic bacteria, can be useful in the treatment of IBD. This review describes the progress in digestive tract prodrug design and delivery in light of gut metabolic activities.

Polymeric formula has direct anti-inflammatory effects on enterocytes in an in vitro model of intestinal inflammation

Exclusive enteral nutrition using polymeric formula (PF) is a well-established therapeutic option for active Crohn's disease; however, its mechanisms of action are unknown. We investigated the anti-inflammatory effects of PF in an in vitro model of epithelial cell inflammation. PF did not affect cell viability over a range of dilutions, but when PF was added to the culture medium the interleukin (IL)-8 response to proinflammatory stimuli was significantly reduced. This effect was due to PF acting directly on the cells as the IL-8 response was still reduced when PF was separated from the proinflammatory stimuli in a 2-compartment system. In the presence of PF, nuclear factor (NF)-kappaB nuclear migration was not inhibited; however, IkappaBalpha degradation was delayed. PF has direct anti-inflammatory effects upon immortalized colonic enterocytes. Therefore PF may, in part, modulate gut inflammation by directly reducing the inflammatory response of the intestinal epithelium.

Comparative efficacies of 2 cysteine prodrugs and a glutathione delivery agent in a colitis model

Oxidant-mediated injury plays an important role in the pathophysiology of inflammatory bowel disease (IBD). Recently, antioxidants were shown to modulate colitis in mice. In this study, the protective effects of L-cysteine and glutathione (GSH) prodrugs are further evaluated against progression of colitis in a murine model. ICR mice were fed compounds incorporated into chow as follows: Group (A) received chow supplemented with vehicle. Group (B) was provided 2-(RS)-n-propylthiazolidine-4(R)-carboxylic-acid (PTCA), a cysteine prodrug. Group (C) received D-ribose-L-cysteine (RibCys), another cysteine prodrug that releases L-cysteine. Group (D) was fed L-cysteine-glutathione mixed sulfide (CySSG), a ubiquitous GSH derivative present in mammalian cells. After 3 days, the animals were further provided with normal drinking water or water supplemented with dextran sodium sulfate (DSS). Mice administered DSS developed severe colitis and suffered weight loss. Colonic lesions significantly improved in animals treated with PTCA and RibCys and, to a lesser extent, with CySSG therapy. Hepatic GSH levels were depleted in colitis animals (control vs DSS, P < 0.001), and normalized with prodrug therapies (control vs treatments, P > 0.05). Protein expressions of serum amyloid A and inflammatory cytokines [interleukin (IL)-6, IL-12, tumor necrosis factor-alpha (TNF-alpha), osteopontin (OPN)] were significantly increased in colitis animals and improved with therapies. Immunohistochemistry and Western blot analyses showed significant upregulation of the macrophage-specific markers, COX-2 and CD68, which suggests macrophage activation and infiltration in the colonic lamina propria in colitis animals. These abnormalities were attenuated in prodrug-treated mice. In conclusion, these data strongly support the novel action of the PTCA against colitis, which further supports a possible therapeutic application for IBD patients.

Revisiting the immunomodulators tacrolimus, methotrexate, and mycophenolate mofetil: their mechanisms of action and role in the treatment of IBD

Inflammatory bowel diseases (IBDs) are thought to result from unopposed immune responses to normal gut flora in a genetically susceptible host. A variety of immunomodulating therapies are applied for the treatment of patients with IBDs. The first-line treatment for IBDs consists of 5-aminosalicylate and/or budesonide. However, these first-line therapies are often not suitable for continuous treatment or do not suffice for the treatment of severe IBD. Recently, efforts have been made to generate novel selective drugs that are more effective and have fewer side effects. Despite promising results, most of these novel drugs are still in a developmental stage and unavailable for clinical application. Yet, another class of established immunomodulators exists that is successful in the treatment of inflammatory bowel diseases. While waiting for emerging novel therapies, the use of these more established drugs should be considered. Furthermore, one of the advantages of using established immunomodulators is the well-documented knowledge on the long-term side effects and on the mechanisms of action. In this review, the authors discuss 3 well-known immunomodulators that are being applied with increased frequency for the treatment of IBD: tacrolimus, methotrexate, and mycophenolate mofetil. These agents have been used for many years as treatment modalities for immunosuppression after organ transplantation, for the treatment of cancer, and for immunomodulation in several other immune-mediated diseases. First, this review discusses the potential targets for immunomodulating therapies in IBDs. Second, the immunomodulating mechanisms and effects of the 3 immunomodulators are discussed in relationship to these treatment targets.

The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function

The mucosal immune system fulfils the primary function of defence against potential pathogens that may enter across vulnerable surface epithelia. However, a secondary function of the intestinal immune system is to discriminate between pathogen-associated and 'harmless' antigens, expressing active responses against the former and tolerance to the latter. Control of immune responses appears to be an active process, involving local generation of IgA and of regulatory and/or regulated T lymphocytes. Two important periods of maximum exposure to novel antigens occur in the young animal, immediately after birth and at weaning. In both cases the antigenic composition of the intestinal contents can shift suddenly, as a result of a novel diet and of colonisation by novel strains and species of bacteria. Changes in lifestyles of man, and husbandry of animals, have resulted in weaning becoming much more abrupt than previously in evolution, increasing the number of antigens that must be simultaneously evaluated by neonates. Thus, birth and weaning are likely to represent hazard and critical control points in the development of appropriate responses to pathogens and harmless dietary and commensal antigens. Neonates are born with relatively undeveloped mucosal immune systems. At birth this factor may prevent both expression of active immune responses and development of tolerance. However, colonisation by intestinal flora expands the mucosal immune system in antigen-specific and non-specific ways. At weaning antibody to fed proteins can be detected, indicating active immune responses to fed proteins. It is proposed that under normal conditions the ability of the mucosal immune system to mount active responses to foreign antigens develops simultaneously with the ability to control and regulate such responses. Problems arise when one or other arm of the immune system develops inappropriately, resulting in inappropriate effector responses to harmless food proteins (allergy) or inadequate responses to pathogens (disease susceptibility).