Compartmentalized expression of Th1 and Th17 cytokines in pediatric inflammatory bowel diseases

Gut-homing and intestinal TIGITnegCD38+ memory T cells acquire an IL-12-induced, ex-Th17 pathogenic phenotype in a subgroup of Crohn's disease patients with a severe disease course

CD4+ memory T cell (TM) reactivation drives chronicity in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis. Defects driving loss of TM regulation likely differ between patients but remain undefined. In health, approximately 40 % of circulating gut-homing CD38+TM express co-inhibitory receptor T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT). TIGIT+CD38+TM have regulatory function while TIGITnegCD38+TM are enriched in IFN-γ-producing cells. We hypothesized TIGITnegCD38+TM are inflammatory and drive disease in a subgroup of IBD patients. We characterized TIGIT+CD38+TM in a uniquely large cohort of pediatric IBD patients from time of diagnosis into adulthood. Circulating TIGITnegCD38+TM frequencies were higher in a subgroup of therapy-naïve CD patients with high plasma IFN-γ and a more severe disease course. TIGITnegCD38+TM were highly enriched in HLA-DR+ and ex-Th17/Th1-like cells, high producers of IFN-γ. Cultures of healthy-adult-stimulated TM identified IL-12 as the only IBD-related inflammatory cytokine to drive the pathogenic ex-Th17-TIGITnegCD38+ phenotype. Moreover, IL12RB2 mRNA expression was higher in TIGITnegCD38+TM than TIGIT+CD38+TM, elevated in CD biopsies compared to controls, and correlated with severity of intestinal inflammation. Overall, we argue that in a subgroup of pediatric CD, increased IL-12 signaling drives reprogramming of Th17 to inflammatory Th1-like TIGITnegCD38+TM and causes more severe disease.

Clinical effectiveness and safety of ustekinumab in youth with refractory inflammatory bowel disease: A retrospective cohort study

BACKGROUND

Inflammatory bowel disease (IBD) incidence and prevalence has been increasing worldwide. Limited data exists on the effectiveness of ustekinumab (UST) in children. We aimed to describe the effectiveness and safety of UST in pediatric patients with IBD.

METHODS

A single-center retrospective study was conducted between January 2017 and February 2022. The study included patients ≤16 years of age who were treated with UST and followed up for ≥1 year. Clinical remission was defined as a score of the Pediatric Crohn's Disease (CD) and Pediatric Ulcerative Colitis (UC) Activity Indices ≤10 at week 52.

RESULTS

Thirteen patients who had failed anti-tumor necrosis factor-α (anti-TNFα) therapy were included, eight (61.5%) with CD and five (38.5%) with UC. The median age was 13 years (interquartile range [IQR]: 11.5 to 14). UST treatment was initiated at a median age of 3 years (IQR: 2.3 to 7) after diagnosis. Ten patients (76.9%) achieved clinical remission. There were no statistically significant differences in characteristics between patients who achieved and did not achieve clinical remission. Biochemical remission (BioR) was achieved in six patients (46.2%). Body mass index (BMI) significantly improved, C-reactive protein (CRP) significantly decreased, and the need for corticosteroids significantly decreased in the remission group. Endoscopy conducted post-treatment in seven patients confirmed remission in six patients. Adverse events included two cases of infection and one of headache.

CONCLUSIONS

UST was effective as a secondary biologic therapy for the induction and maintenance of remission in patients with anti-TNFα refractory IBD. At one year, 84% of patients remained on UST with no severe adverse reactions reported.

Interleukin-10 production by innate lymphoid cells restricts intestinal inflammation in mice

Interleukin-10 (IL-10) is an immunomodulatory cytokine critical for intestinal immune homeostasis. IL-10 is produced by various immune cells but IL-10 receptor signaling in intestinal CX3CR1+ mononuclear phagocytes is necessary to prevent spontaneous colitis in mice. Here, we utilized fluorescent protein reporters and cell-specific targeting and found that Rorc-expressing innate lymphoid cells (ILCs) produce IL-10 in response to anti-CD40-mediated intestinal inflammation. Deletion of Il10 specifically in Rorc-expressing ILCs led to phenotypic changes in intestinal macrophages and exacerbated both innate and adaptive immune-mediated models of experimental colitis. The population of IL-10+ producing ILCs shared markers with both ILC2 and ILC3 with nearly all ILC3s being of the NCR+ subtype. Interestingly, Ccl26 was enriched in IL-10+ ILCs and was markedly reduced in IL-10-deficient ILC3s. Since CCL26 is a ligand for CX3CR1, we employed RNA in situ hybridization and observed increased numbers of ILCs in close proximity to Cx3cr1-expressing cells under inflammatory conditions. Finally, we generated transgenic RorctdTomato reporter mice that faithfully marked RORγt+ cells that could rescue disease pathology and aberrant macrophage phenotype following adoptive transfer into mice with selective Il10 deficiency in ILC3s. These results demonstrate that IL-10 production by a population of ILCs functions to promote immune homeostasis in the intestine possibly via direct effects on intestinal macrophages.

Combined plasma protein and memory T cell profiling discern IBD-patient-immunotypes related to intestinal disease and treatment outcomes

Inflammatory bowel disease (IBD) chronicity results from memory T helper cell (Tmem) reactivation. Identifying patient-specific immunotypes is crucial for tailored treatment. We conducted a comprehensive study integrating circulating immune proteins and circulating Tmem, with intestinal tissue histology and mRNA analysis, in therapy-naïve pediatric IBD (Crohn's disease, CD: n = 62; ulcerative colitis, UC: n = 20; age-matched controls n = 43), and after 10-12 weeks' induction therapy. At diagnosis, plasma protein profiles unveiled two UC and three CD clusters with distinct disease courses. UC patients displayed unchanged circulating Tmem, while CD exhibited increased frequencies of gut-homing ex-Th17, known for high IFN-γ production. UC#2 had elevated Th17/neutrophil-pathway-related proteins and severe disease, with higher endoscopic and histological damage and Th17/neutrophil infiltration. Although both UC#1 and UC#2 responded to therapy, UC#2 required earlier immunomodulation. CD#3 had lower plasma protein concentrations, especially IFN-γ pathway proteins, fewer gut-homing ex-Th17 and clinically milder disease, confirmed by intestinal gene expression. CD#1 and CD#2 had comparably high Th1-related immune profiles, but CD#1 exhibited higher concentrations of proteins previously associated with poorer prognosis. Both CD clusters responded to induction therapy, with similar one-year outcomes. This study highlights feasibility of discriminating patient-specific immunotypes in IBD, advancing our understanding of immune pathogenesis, needed for tailored treatment strategies.

Oral Delivery of miR146a Conjugated to Cerium Oxide Nanoparticles Improves an Established T Cell-Mediated Experimental Colitis in Mice

Background: Dysregulated inflammation and oxidative stress are strongly implicated in the pathogenesis of inflammatory bowel disease. We have developed a novel therapeutic that targets inflammation and oxidative stress. It is comprised of microRNA-146a (miR146a)-loaded cerium oxide nanoparticles (CNPs) (CNP-miR146a). We hypothesized that oral delivery of CNP-miR146a would reduce colonic inflammation in a mouse model of established, chronic, T cell-mediated colitis. Methods: The stability of CNP-miR146a and mucosal delivery was assessed in vitro with simulated gastrointestinal fluid and in vivo after oral gavage by quantitative real-time RT-PCR. The efficacy of orally administered CNP-miR146a was tested in mice with established colitis using the model of adoptive naïve T-cell transfer in recombinant activating gene 2 knockout (Rag2-/-) mice. Measured outcomes included histopathology; CD45+ immune cell infiltration; oxidative DNA damage (tissue 8-hydroxy-2'-deoxyguanosine; 8-OHdG); expression of IL-6 and TNF mRNA and protein, and flow cytometry analysis of lamina propria Th1 and Th17 cell populations. Results: miR146a expression remained stable in simulated gastric and intestinal conditions. miR146a expression increased in the intestines of mice six hours following oral gavage of CNP-miR146a. Oral delivery of CNP-miR146a in mice with colitis was associated with reduced inflammation and oxidative stress in the proximal and distal colons as evidenced by histopathology scoring, reduced immune cell infiltration, reduced IL-6 and TNF expression, and decreased populations of CD4+Tbet+IFNg+ Th1, CD4+RorgT+IL17+ Th17, as well as pathogenic double positive IFNg+IL17+ T cells. Conclusions: CNP-miR146a represents a novel orally available therapeutic with high potential to advance into clinical trials.

Ulcerative colitis: molecular insights and intervention therapy

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by abdominal pain, diarrhea, rectal bleeding, and weight loss. The pathogenesis and treatment of UC remain key areas of research interest. Various factors, including genetic predisposition, immune dysregulation, and alterations in the gut microbiota, are believed to contribute to the pathogenesis of UC. Current treatments for UC include 5-aminosalicylic acids, corticosteroids, immunosuppressants, and biologics. However, study reported that the one-year clinical remission rate is only around 40%. It is necessary to prompt the exploration of new treatment modalities. Biologic therapies, such as anti-TNF-α monoclonal antibody and JAK inhibitor, primarily consist of small molecules targeting specific pathways, effectively inducing and maintaining remission. Given the significant role of the gut microbiota, research into intestinal microecologics, such as probiotics and prebiotics, and fecal microbiota transplantation (FMT) shows promising potential in UC treatment. Additionally, medicinal herbs, such as chili pepper and turmeric, used in complementary therapy have shown promising results in UC management. This article reviews recent findings on the mechanisms of UC, including genetic susceptibility, immune cell dynamics and cytokine regulation, and gut microbiota alterations. It also discusses current applications of biologic therapy, herbal therapy, microecologics, and FMT, along with their prospects and challenges.

Unraveling Cross-Organ Impacts of Airborne Pollutants: A Multiomics Study on Respiratory Exposure and Gastrointestinal Health

Poor air quality is increasingly linked to gastrointestinal diseases, suggesting a potential correlation with human intestine health. However, this relationship remains largely unexplored due to limited research. This study used a controlled mouse model exposed to cooking oil fumes (COFs) and metagenomics, transcriptomics, and metabolomics to elucidate interactions between intestine microbiota and host metabolism under environmental stress. Our findings reveal that short-term COF inhalation induces pulmonary inflammation within 3 days and leads to gastrointestinal disturbances, elucidating a pathway connecting respiratory exposure to intestinal dysfunction. The exposure intensity significantly correlates with changes in intestinal tissue integrity, microbial composition, and metabolic function. Extended exposure of 7 days disrupts intestine microbiota and alters tryptophan metabolism, with further changes observed after 14 days, highlighting an adaptive response. These results highlight the vulnerability of intestinal health to airborne pollutants and suggest a pathway through which inhaled pollutants may affect distant organ systems.

Comparing the Effects of Anti-TNF Agent and Ustekinumab on Small Bowel Inflammation in Crohn's Disease: Inverse Probability Weighting With Stabilized Weights of Propensity Scores

Background

Endoscopic mucosal healing serves as a critical predictor for achieving long-term remission in Crohn's disease treatment. Recent data indicate that the effectiveness of healing varies based on the location of gastrointestinal inflammation. Additionally, reports suggest that antitumor necrosis factor-α (anti-TNF-α) agents exhibit reduced efficacy in treating small intestinal inflammation compared to colorectal inflammation. Conversely, limited research exists regarding the impact of the anti-IL12/23 agent ustekinumab (UST) on small intestinal inflammation. This study aimed to compare the effects of anti-TNF-α agents and UST on small intestinal inflammation using propensity score analysis.

Methods

This retrospective observational study involved 70 patients with Crohn's disease who had inflammation in the small intestine and had initiated treatment with either anti-TNF agents or UST between March 2015 and August 2021. Endoscopic findings were evaluated before treatment commencement and at 1-2 years post-treatment initiation. The propensity score was employed to compare the efficacy of TNF agents and UST on small bowel inflammation.

Results

Ustekinumab exhibited greater improvement in the small intestinal endoscopy score than anti-TNF-α antibodies according to the propensity score analysis (inverse probability weighting; P = .0448). However, no significant disparity was observed in the overall improvement of endoscopic scores between UST and anti-TNF-α antibodies (P = .5938).

Conclusions

This study suggests that UST might be more effective than anti-TNF-α agents in treating small intestinal inflammation in Crohn's disease.

Synergistic effect of berberine hydrochloride and dehydrocostus lactone in the treatment of ulcerative colitis: Take gut microbiota as the target

Ulcerative colitis (UC) is a difficult-to-cure and recurrent inflammatory bowel disease, and it is difficult to maintain long-term results with a single drug. Inspired by clinical medication in traditional Chinese medicine, we used berberine hydrochloride (BBH) and dehydrocostus lactone (DEH) in combination for the first time and focused on studying their mechanism of treating UC based on gut microbiota. Therefore, we evaluated the therapeutic effects of BBH and DEH on DSS-induced UC mice using ELISA, HE and AB-PAS staining, 16s rDNA amplicon sequencing technology, and fecal transplantation experiments (FMT). In this study, the combination of BBH and DEH significantly relieved symptoms, colonic inflammation, and intestinal barrier damage of DSS-induced UC mice, and they did not show antagonism. In addition, the co-administration of BBH and DEH altered the composition and function of gut microbiota, with BBH increasing the abundance of key beneficial bacterial genus Akkermansia and DEH aiming to enhance species diversity and supplying intestinal proteins to prevent overconsumption. Furthermore, our data showed that BBH and DEH improve the levels of short-chain fatty acids, which also proved the positive regulation of gut microbiota by BBH and DEH. Finally, the FMT confirmed the strong correlation between BBH, DEH, and the gut microbiota. In conclusion, the co-administration of BBH and DEH protected the intestinal barrier and reduced inflammatory damage by regulating gut microbiota, targeting the key beneficial bacterial genus Akkermansia, and maintaining a normal supply of intestinal proteins.

Molecular analyses of ADAMTS-1, -4, -5, and IL-17 a cytokine relationship in patients with ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that develops due to the impaired immune response in genetically susceptible individuals, and its etiopathogenesis is not fully elucidated. IL-17 A is a cytokine that is produced by a type of immune cell called Th17 cells and is involved in the immune response and inflammation. On the other hand, ADAMTS-1, -4, and - 5 are enzymes that are involved in the breakdown of extracellular matrix proteins, including proteoglycans, which are important components of the intestinal wall. This study aimed to evaluate the relationship between interleukin 17 (IL-17 A) cytokine, which plays a role in the pathogenesis of ulcerative colitis, and the inflammation-controlled a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1, -4, and - 5 protein members.

METHODS

Bowel tissue samples and blood serum from 51 patients with UC and 51 healthy controls were included in this study. mRNA expression levels of the ADAMTS-1, -4, -5, and IL-17 A were analyzed by RT-qPCR, and immunohistochemical analyses were performed to evaluate ADAMTS-1, -4, -5, and IL-17 A proteins in tissue samples. In addition, ELISA analysis determined serum levels of the ADAMTS-1, -4, -5, and IL-17 A.

RESULTS

RT-qPCR results reveal that the expression of ADAMTS-1, -4, -5, and IL-17 A genes in the UC tissue samples were significantly high according to the control tissue samples. Also, ADAMTS-1, -4, -5, and IL-17 A proteins revealed enhanced expression pattern UC groups according to the control. Also, ADAMTS-1, -4, -5, and IL-17 A protein showed cytoplasmic localization patterns in both control and UC groups. The serum levels of ADAMTS-1,-5, and IL-17 A were significantly higher in UC samples than in the control group.

CONCLUSIONS

We observed a positive correlation between the ADAMTS-1, -5 and IL17A cytokine expression in UC samples. These results provide a new understanding of controlling crucial ADAMTS family protein members by IL-17 A cytokines with UC.

Are We Ready to Reclassify Crohn's Disease Using Molecular Classification?

Crohn's disease (CD) is a type of inflammatory bowel disease. The number of IBD cases worldwide was estimated to be 4.9 million in 2019. CD exhibits heterogeneity in clinical presentation, anatomical involvement, disease behaviour, clinical course and response to treatment. The classical description of CD involves transmural inflammation with skip lesions anywhere along the entire gastrointestinal tract. The complexity and heterogeneity of Crohn's disease is not currently reflected in the conventional classification system. Though the knowledge of Crohn's pathophysiology remains far from understood, the established complex interplay of the omics-genomics, transcriptomics, proteomics, epigenomics, metagenomics, metabolomics, lipidomics and immunophenomics-provides numerous targets for potential molecular markers of disease. Advancing technology has enabled identification of small molecules within these omics, which can be extrapolated to differentiate types of Crohn's disease. The multi-omic future of Crohn's disease is promising, with potential for advancements in understanding of its pathogenesis and implementation of personalised medicine.

Intestinal Barrier Healing Is Superior to Endoscopic and Histologic Remission for Predicting Major Adverse Outcomes in Inflammatory Bowel Disease: The Prospective ERIca Trial

BACKGROUND & AIMS

Endoscopic and histologic remission have emerged as key therapeutic goals in the management of inflammatory bowel diseases (IBD) that are associated with favorable long-term disease outcomes. Here, we prospectively compared the predictive value of barrier healing with endoscopic and histologic remission for predicting long-term disease behavior in a large cohort of patients with IBD in clinical remission.

METHODS

At baseline, patients with IBD in clinical remission underwent ileocolonoscopy with assessment of intestinal barrier function by confocal endomicroscopy. Endoscopic and histologic disease activity, as well as barrier healing, was prospectively assessed along established scores. During subsequent follow-up, patients were closely monitored for clinical disease activity and the occurrence of major adverse outcomes (MAOs): disease flares, IBD-related hospitalization or surgery, and initiation or dose escalation of systemic steroids, immunosuppressants, small molecules, or biological therapy.

RESULTS

The final analysis included 181 patients, 100 with Crohn's disease [CD] and 81 with ulcerative colitis (UC). During a mean follow-up of 35 (CD) and 25 (UC) months, 73% of patients with CD and 69% of patients with UC experienced at least 1 MAO. The probability of MAO-free survival was significantly higher in patients with IBD with endoscopic remission compared with endoscopically active disease. In addition, histologic remission predicted MAO-free survival in patients with UC but not CD. Barrier healing on endomicroscopy was superior to endoscopic and histologic remission for predicting MAO-free survival in both UC and CD.

CONCLUSIONS

Barrier healing is associated with decreased risk of disease progression in patients with clinically remittent IBD, with superior predictive performance compared with endoscopic and histologic remission. Analysis of barrier function might be considered as a future treatment target in clinical trials.

CLINICALTRIALS

gov number, NCT05157750.

Therapeutic potential of mesenchymal stem/stromal cells (MSCs)-based cell therapy for inflammatory bowel diseases (IBD) therapy

Recently, mesenchymal stem/stromal cells (MSCs) therapy has become an emerging therapeutic modality for the treatment of inflammatory bowel disease (IBD), given their immunoregulatory and pro-survival attributes. MSCs alleviate dysregulated inflammatory responses through the secretion of a myriad of anti-inflammatory mediators, such as interleukin 10 (IL-10), transforming growth factor-β (TGFβ), prostaglandin E2 (PGE2), tumor necrosis factor-stimulated gene-6 (TSG-6), etc. Indeed, MSC treatment of IBD is largely carried out through local microcirculation construction, colonization and repair, and immunomodulation, thus alleviating diseases severity. The clinical therapeutic efficacy relies on to the marked secretion of various secretory molecules from viable MSCs via paracrine mechanisms that are required for gut immuno-microbiota regulation and the proliferation and differentiation of surrounding cells like intestinal epithelial cells (IECs) and intestinal stem cells (ISCs). For example, MSCs can induce IECs proliferation and upregulate the expression of tight junction (TJs)-associated protein, ensuring intestinal barrier integrity. Concerning the encouraging results derived from animal studies, various clinical trials are conducted or ongoing to address the safety and efficacy of MSCs administration in IBD patients. Although the safety and short-term efficacy of MSCs administration have been evinced, the long-term efficacy of MSCs transplantation has not yet been verified. Herein, we have emphasized the illumination of the therapeutic capacity of MSCs therapy, including naïve MSCs, preconditioned MSCs, and also MSCs-derived exosomes, to alleviate IBD severity in experimental models. Also, a brief overview of published clinical trials in IBD patients has been delivered.

IL-23 Blockade in Anti-TNF Refractory IBD: From Mechanisms to Clinical Reality

Increasing insights into the immunopathogenesis of inflammatory bowel diseases [IBD] have led to the advent of targeted therapies that inhibit crucial mediators of the inflammatory process, thereby widening our available therapeutic armamentarium. Anti-tumour necrosis factor [anti-TNF] agents are still a mainstay of our therapeutic endeavours and the introduction of corresponding biosimilars has further widened their use. Nevertheless, only a subgroup of treated patients benefit from the initiated treatment and there is secondary non-response in the course of therapy. Initiation of subsequent therapy often poses a challenge to the treating physician, as non-response to primary anti-TNF treatment generally characterizes a patient group that is more treatment-resistant, which may be due to the immunological impregnation by prior anti-TNF exposure. At present, there is currently no guidance for the most appropriate second-line therapy after anti-TNF failure. Here, we review the efficacy of secondary biological therapy in anti-TNF-treated patients. We focus on and assess available clinical trial data of the emerging substance class of IL-23p19 inhibitors, which have demonstrated remarkable efficacy not only in anti-TNF-naïve but also refractory patients. We present molecular mechanisms that drive IL-23-mediated resistance to ongoing anti-TNF therapy and discuss the dynamic fluidity of the mucosal cytokine network in the course of therapy that perpetuates the mucosal inflammatory reaction. Translation of these findings into clinical practice might finally lead to initiation of the most appropriate therapy at the right time of the individual disease course, which would have important implications for the patient's probability of response to treatment.

Time to Revisit Disease Classification in Inflammatory Bowel Disease: Is the Current Classification of Inflammatory Bowel Disease Good Enough for Optimal Clinical Management?

Inflammatory bowel disease (IBD), historically subdivided into Crohn's disease and ulcerative colitis, is a very heterogeneous condition. While the tendency in medicine is to try to reduce complexity, IBD is a disease that cannot justify a one-size-fits-all principle. Our current clinical classification tools are suboptimal and need further refinement to capture, at least in part, the variety of phenotypes encountered in daily clinical practice. Although these revised classification tools alone will not be sufficient and should be complemented by more detailed molecular subclassifications, optimized clinical phenotypes can contribute to improved trial designs, future translational research approaches, and better treatment outcomes. In the current review, we discuss key clinical features important in IBD disease heterogeneity, tackle limitations of the current classification systems, propose some potential improvements, and raise priorities for future research in this domain.

Therapeutic drug monitoring for biological medications in inflammatory bowel disease

Therapeutic drug monitoring (TDM) is the measurement of serum drug concentrations and anti-drug-antibodies (ADA) for biologic therapies used to treat inflammatory bowel disease (IBD). The aim of this article is to review the current literature concerning reactive and proactive TDM for both adults and children with IBD. Although optimal trough concentration windows for some of these medications are not well defined, there is mounting evidence to suggest that reactive TDM is associated with favorable therapeutic outcomes, including less immunogenicity, greater drug exposure, and a decreased risk of treatment failure. Moreover, while the exact mechanism of loss of response is not fully elucidated, the vast majority of studies have reported a decreased incidence of nonresponse and secondary loss of response when TDM is implemented. Proactive TDM, while even less understood in the literature, employs a schedule of preemptive analysis of serum trough concentrations to accordingly adjust the patient's biologic dosage. Proactive TDM may decrease the need for IBD-related surgery/hospitalization, and therefore merits future studies of investigation.

Review article: distinctions between ileal and colonic Crohn's disease: from physiology to pathology

BACKGROUND

Ileal and colonic Crohn's disease seem to be two separate entities.

AIMS

To describe the main physiological distinctions between the small and the large intestine and to analyse the differences between ileal and colonic Crohn's disease.

METHODS

The relevant literature was critically examined and synthesised.

RESULTS

The small and large intestine have fundamental distinctions (anatomy, cellular populations, immune defence, microbiota). The differences between ileal and colonic Crohn's disease are highlighted by a heterogeneous body of evidence including clinical features (natural history of the disease, efficacy of treatments, and monitoring), epidemiological data (smoking status, age, gender) and biological data (genetics, microbiota, immunity, mesenteric fat). However, the contribution of these factors to disease location remains poorly understood.

CONCLUSION

The classification of ileal and colonic Crohn's disease as distinct subphenotypes is well supported by the literature. Understanding of these differences could be exploited to develop more individualised patient care.

Location is important: differentiation between ileal and colonic Crohn's disease

Crohn's disease can affect any part of the gastrointestinal tract; however, current European and national guidelines worldwide do not differentiate between small-intestinal and colonic Crohn's disease for medical treatment. Data from the past decade provide evidence that ileal Crohn's disease is distinct from colonic Crohn's disease in several intestinal layers. Remarkably, colonic Crohn's disease shows an overlap with regard to disease behaviour with ulcerative colitis, underlining the fact that there is more to inflammatory bowel disease than just Crohn's disease and ulcerative colitis, and that subtypes, possibly defined by location and shared pathophysiology, are also important. This Review provides a structured overview of the differentiation between ileal and colonic Crohn's disease using data in the context of epidemiology, genetics, macroscopic differences such as creeping fat and histological findings, as well as differences in regard to the intestinal barrier including gut microbiota, mucus layer, epithelial cells and infiltrating immune cell populations. We also discuss the translation of these basic findings to the clinic, emphasizing the important role of treatment decisions. Thus, this Review provides a conceptual outlook on a new mechanism-driven classification of Crohn's disease.

Innate Lymphoid Cells in Intestinal Homeostasis and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a heterogeneous state of chronic intestinal inflammation of unknown cause encompassing Crohn’s disease (CD) and ulcerative colitis (UC). IBD has been linked to genetic and environmental factors, microbiota dysbiosis, exacerbated innate and adaptive immunity and epithelial intestinal barrier dysfunction. IBD is classically associated with gut accumulation of proinflammatory Th1 and Th17 cells accompanied by insufficient Treg numbers and Tr1 immune suppression. Inflammatory T cells guide innate cells to perpetuate a constant hypersensitivity to microbial antigens, tissue injury and chronic intestinal inflammation. Recent studies of intestinal mucosal homeostasis and IBD suggest involvement of innate lymphoid cells (ILCs). These lymphoid-origin cells are innate counterparts of T cells but lack the antigen receptors expressed on B and T cells. ILCs play important roles in the first line of antimicrobial defense and contribute to organ development, tissue protection and regeneration, and mucosal homeostasis by maintaining the balance between antipathogen immunity and commensal tolerance. Intestinal homeostasis requires strict regulation of the quantity and activity of local ILC subpopulations. Recent studies demonstrated that changes to ILCs during IBD contribute to disease development. A better understanding of ILC behavior in gastrointestinal homeostasis and inflammation will provide valuable insights into new approaches to IBD treatment. This review summarizes recent research into ILCs in intestinal homeostasis and the latest advances in the understanding of the role of ILCs in IBD, with particular emphasis on the interaction between microbiota and ILC populations and functions.

Novel trends with biologics in inflammatory bowel disease: sequential and combined approaches

Inflammatory bowel disease (IBD) management has changed dramatically over the past 20 years, after the introduction of targeted biological therapies. However, the impact of these new drugs in changing the natural history of disease is still under debate. Recent evidence seems to suggest that the extent of their efficacy might be, at least partially, dependent on the timing of their introduction and on the subsequent management strategy. In this complex landscape, the potential role for a more dynamic approach with treatments based on sequencing and combining targeted therapies has been explored only minimally so far. In this review, we aim to explore the potential biological rationale behind the use of sequential and combination therapies in IBD, to summarise the current knowledge on this topic and to propose a management algorithm that combines these notions.

Predictors and Early Markers of Response to Biological Therapies in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) are chronic conditions that primarily affect the gastrointestinal tract, with a complex pathogenesis; they are characterized by a significant heterogeneity of clinical presentations and of inflammatory pathways that sustain intestinal damage. After the introduction of the first biological therapies, the pipeline of therapies for IBD has been constantly expanding, and a significant number of new molecules is expected in the next few years. Evidence from clinical trials and real-life experiences has taught us that up to 40% of patients do not respond to a specific drug. Unfortunately, to date, clinicians lack a valid tool that can predict each patient’s response to therapies and that could help them in choosing what drug to administer. Several candidate biomarkers have been investigated so far, with conflicting results: clinical, genetic, immunological, pharmacokinetic and microbial markers have been tested, but no ideal marker has been identified so far. Based on recent evidence, multiparametric models seemingly hold the greatest potential for predicting response to therapy. In this narrative review, we aim to summarize the current knowledge on predictors and early markers of response to biological therapies in IBD.

Th17 Cells in Inflammatory Bowel Disease: Cytokines, Plasticity, and Therapies

Autoimmune diseases (such as rheumatoid arthritis, asthma, autoimmune bowel disease) are a complex disease. Improper activation of the immune system or imbalance of immune cells can cause the immune system to transform into a proinflammatory state, leading to autoimmune pathological damage. Recent studies have shown that autoimmune diseases are closely related to CD4+ T helper cells (Th). The original CD4 T cells will differentiate into different T helper (Th) subgroups after activation. According to their cytokines, the types of Th cells are different to produce lineage-specific cytokines, which play a role in autoimmune homeostasis. When Th differentiation and its cytokines are not regulated, it will induce autoimmune inflammation. Autoimmune bowel disease (IBD) is an autoimmune disease of unknown cause. Current research shows that its pathogenesis is closely related to Th17 cells. This article reviews the role and plasticity of the upstream and downstream cytokines and signaling pathways of Th17 cells in the occurrence and development of autoimmune bowel disease and summarizes the new progress of IBD immunotherapy.

Induction of colitis-associated neoplasia in mice using azoxymethane and dextran sodium sulfate

Long-standing inflammatory bowel diseases (IBD) increase the risk for the development of colorectal cancer (CRC). This increase is due in large part to chronic intestinal inflammation which exposes the epithelium to pro-carcinogenic factors. Moreover, enhanced mucosal proliferation associated with repetitive wound healing events following an inflammatory episode, further enhance this pro-tumorigenic environment. Although multiple factors involved in IBD pathogenesis and its associated neoplasia have been identified, more work is needed to develop and improve therapies to ameliorate disease and thus reduce CRC risk. Murine models have served as useful tools to identify factors involved in the pathogenesis of colitis-associated neoplasia and test therapies. These include both chemically-induced and genetic engineering approaches, resulting in chronic inflammation and tumor development. Here, we present a step-by-step method of inducing inflammation-associated colon neoplasia by combining administration of azoxymethane and dextran sodium sulfate in mice. A detailed description of this methodology will facilitate its use in the scientific community with the goals of further elucidating the mechanisms underlying colitis-associated tumorigenesis and developing risk reducing interventions.

Zinc Deficiency Activates the IL-23/Th17 Axis to Aggravate Experimental Colitis in Mice

BACKGROUND AND AIMS

Patients with inflammatory bowel disease [IBD], especially Crohn's disease, often develop zinc deficiency. However, the precise mechanisms by which zinc deficiency affects IBD pathology, particularly intestinal macrophage function, remain unclear. We studied the effects of zinc deficiency on the development and progression of colitis in mice.

METHODS

To induce colitis, mice were treated with 2,4,6-trinitrobenzene sulphonic acid. Rag1-/- mice were then given injections of naïve CD4+CD62L+ T cells. The respective degrees of mucosal injury of mice that had received a zinc chelator (TPEN; N,N,N',N'-tetrakis [2-pyridylmethyl]ethylenediamine) and of control mice were subsequently compared. Colonic lamina propria mononuclear cells were isolated by enzymatic digestion and were examined using flow cytometry. To generate mouse bone marrow-derived macrophages [BMDMs], bone marrow cells were stimulated with mouse macrophage-colony stimulating factor.

RESULTS

Zinc deficiency aggravates colonic inflammation through the activation of type 17 helper T [Th17] cells in mice. Flow cytometric analysis revealed that zinc deficiency significantly increases the proportion of pro-inflammatory [M1] macrophages in colonic lamina propria mononuclear cells obtained from inflamed colon. Interferon-γ plus lipopolysaccharide-mediated M1 skewing alters the expression of zinc transporters in BMDMs and thereby decreases the intracellular free zinc. TPEN treatment mimicking the effects of the M1 skewing up-regulates IL-23p19 expression, which is strongly related to Th17 development. Furthermore, the nuclear accumulation of interferon-regulatory factor 5 is closely involved in IL-23p19 induction in zinc-deficient macrophages.

CONCLUSIONS

Zinc deficiency aggravates colonic inflammation through activation of the IL-23/Th17 axis. This activation is controlled by subcellular distribution of interferon-regulatory factor 5.

Immunomodulatory Effect of Urine-derived Stem Cells on Inflammatory Bowel Diseases via Downregulating Th1/Th17 Immune Responses in a PGE2-dependent Manner

BACKGROUND AND AIMS

Despite the therapeutic promise of stem cell therapy in the treatment of inflammatory bowel diseases [IBD], most donor cell populations have to be obtained via invasive approaches and often remain insufficiently validated. Urine-derived stem cells [USC] were recently shown to have regenerative properties and can be harvested in a safe, low-cost, and noninvasive way. This study aims to evaluate the immunomodulatory effect of USC and their efficacy in the management of IBD.

METHODS

Human USC were isolated and expanded from the urine of healthy male adult volunteers [n = 3, age range 24-30 years]. USC were characterised by cell surface marker expression profile and multipotent differentiation. The in vitro immunomodulatory effect of USC was evaluated by co-culturing with human CD4+ T cells upon stimulation with phytohaemagglutinin [PHA]. The proliferation of CD4+ T was measured by fluorescence-activated cell sorting [FACS]. Cytokine array and quantitative real-time polymerase chain reaction [RT-PCR] were applied to examine cytokine levels. In vivo therapeutic value of USC was assessed using a murine colitis model induced by dextran sulphate sodium [DSS] or 2, 4, 6-trinitrobenzene sulphonic acid [TNBS]. The immunomodulatory effect of USC and bone marrow-derived mesenchymal stem cells [BMSC] was compared when co-cultured with CD4+ T cells. The therapeutic efficacy of USC and BMSC on IBD was compared when administered in an acute DSS model in vivo.

RESULTS

USC were positive for mesenchymal stem cell markers but were negative for haematopoietic stem cell markers. These cells differentiated into osteo-, adipo-, and chondrogenic cell lineages. Similar to BMSC, the proliferation of CD4+ T cells was significantly inhibited when co-cultured with USC, as a consequence of Th1/Th17 immune response inhibition. Systemic administration of USC significantly ameliorated the clinical and histopathological severity of colitis and increased the survival rate in both acute and chronic murine colitis models. Moreover, implantation of USC led to downregulation of the Th1/Th17 immune responses in a PGE2-dependent manner.

CONCLUSIONS

This study demonstrated that implantation of USC reduces inflammation in an IBD rodent model via downregulation of Th1/Th17 immune responses, indicating that USC therapy serves as a potential cell-based therapeutic candidate treatment for IBD.

Interplay between Cytokine Circuitry and Transcriptional Regulation Shaping Helper T Cell Pathogenicity and Plasticity in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic disorder manifested as Crohn’s disease (CD) and ulcerative colitis (UC) characterized by intestinal inflammation and involves a dysregulated immune response against commensal microbiota through the activation of CD4 T helper cells. T helper cell differentiation to effector or regulatory phenotypes is controlled by cytokine networks and transcriptional regulators. Distinct polarized T helper cells are able to alter their phenotypes to adapt to diverse and fluctuating physiological environments. T helper cells exhibit intrinsic instability and flexibility to express cytokines of other lineages or transdifferentiate from one T helper cell type to another in response to various perturbations from physiological cytokine milieu as a means of promoting local immunity in response to injury or ensure tissue homeostasis. Furthermore, functional plasticity and diversity of T helper cells are associated with pathogenicity and are critical for immune homeostasis and prevention of autoimmunity. In this review, we provide deeper insights into the combinatorial extrinsic and intrinsic signals that control plasticity and transdifferentiation of T helper cells and also highlight the potential of exploiting the genetic reprogramming plasticity of T helper cells in the treatment of IBD.

The early life microbiota protects neonatal mice from pathological small intestinal epithelial cell shedding

The early life gut microbiota plays a crucial role in regulating and maintaining the intestinal barrier, with disturbances in these communities linked to dysregulated renewal and replenishment of intestinal epithelial cells. Here we sought to determine pathological cell shedding outcomes throughout the postnatal developmental period, and which host and microbial factors mediate these responses. Surprisingly, neonatal mice (Day 14 and 21) were highly refractory to induction of cell shedding after intraperitoneal administration of liposaccharide (LPS), with Day 29 mice showing strong pathological responses, more similar to those observed in adult mice. These differential responses were not linked to defects in the cellular mechanisms and pathways known to regulate cell shedding responses. When we profiled microbiota and metabolites, we observed significant alterations. Neonatal mice had high relative abundances of Streptococcus, Escherichia, and Enterococcus and increased primary bile acids. In contrast, older mice were dominated by Candidatus Arthromitus, Alistipes, and Lachnoclostridium, and had increased concentrations of SCFAs and methyamines. Antibiotic treatment of neonates restored LPS-induced small intestinal cell shedding, whereas adult fecal microbiota transplant alone had no effect. Our findings further support the importance of the early life window for microbiota-epithelial interactions in the presence of inflammatory stimuli and highlights areas for further investigation.

IFN-γ and IL-17A regulate intestinal crypt production of CXCL10 in the healthy and inflamed colon

During intestinal inflammation, immature cells within the intestinal crypt are called upon to replenish lost epithelial cell populations, promote tissue regeneration, and restore barrier integrity. Inflammatory mediators including TH1/TH17-associated cytokines influence tissue health and regenerative processes, yet how these cytokines directly influence the colon crypt epithelium and whether the crypt remains responsive to these cytokines during active damage and repair, remain unclear. Here, using laser-capture microdissection and primary colon organoid culture, we show that the cytokine milieu regulates the ability of the colonic crypt epithelium to participate in proinflammatory signaling. IFN-γ induces the TH1-recruiting, proinflammatory chemokine CXCL10/IP10 in primary murine intestinal crypt epithelium. CXCL10 was also induced in colonic organoids derived from mice with active, experimentally induced colitis, suggesting that the crypt can actively secrete CXCL10 in select cytokine environments during colitis. Colon expression of cxcl10 further increased during infectious and noninfectious colitis in Il17a-/- mice, demonstrating that IL-17A exerts a negative effect on CXCL10 in vivo. Furthermore, IL-17A directly antagonized CXCL10 production in ex vivo organoid cultures derived from healthy murine colons. Interestingly, direct antagonism of CXCL10 was not observed in organoids derived from colitic mouse colons bearing active lesions. These data, highlighting the complex interplay between the cytokine milieu and crypt epithelia, demonstrate proinflammatory chemokines can be induced within the colonic crypt and suggest the crypt remains responsive to cytokine modulation during inflammation.NEW & NOTEWORTHY Upon damage, the intestinal epithelium regenerates to restore barrier function. Here we observe that the local colonic cytokine milieu controls the production of procolitic chemokines within the crypt base and colon crypts remain responsive to cytokines during inflammation. IFN-γ promotes, while IL-17 antagonizes, CXCL10 production in healthy colonic crypts, while responses to cytokines differ in inflamed colon epithelium. These data reveal novel insight into colon crypt responses and inflammation-relevant alterations in signaling.

Dissecting the Heterogeneity in T-Cell Mediated Inflammation in IBD

Infiltration of the lamina propria by inflammatory CD4+ T-cell populations is a key characteristic of chronic intestinal inflammation. Memory-phenotype CD4+ T-cell frequencies are increased in inflamed intestinal tissue of IBD patients compared to tissue of healthy controls and are associated with disease flares and a more complicated disease course. Therefore, a tightly controlled balance between regulatory and inflammatory CD4+ T-cell populations is crucial to prevent uncontrolled CD4+ T-cell responses and subsequent intestinal tissue damage. While at steady state, T-cells display mainly a regulatory phenotype, increased in Th1, Th2, Th9, Th17, and Th17.1 responses, and reduced Treg and Tr1 responses have all been suggested to play a role in IBD pathophysiology. However, it is highly unlikely that all these responses are altered in each individual patient. With the rapidly expanding plethora of therapeutic options to inhibit inflammatory T-cell responses and stimulate regulatory T-cell responses, a crucial need is emerging for a robust set of immunological assays to predict and monitor therapeutic success at an individual level. Consequently, it is crucial to differentiate dominant inflammatory and regulatory CD4+ T helper responses in patients and relate these to disease course and therapy response. In this review, we provide an overview of how intestinal CD4+ T-cell responses arise, discuss the main phenotypes of CD4+ T helper responses, and review how they are implicated in IBD.

Should We Divide Crohn's Disease Into Ileum-Dominant and Isolated Colonic Diseases?

Crohn's disease (CD) is an inflammatory bowel disease that can involve any region of the gastrointestinal tract. First described in 1932 as terminal ileitis or regional enteritis, it predominately involves the ileum with or without colonic involvement. Isolated colonic CD was first described in 1960 and since then the phenotypic classification of CD has evolved to stratify patients into isolated ileal, ileocolonic, or isolated colonic involvement. In the current review we evaluate the published literature regarding differences in epidemiology, natural history, pathogenesis, response to therapy, and disease monitoring, when stratified by disease location. Based on the available evidence consideration could be given to a new classification for CD, which splits it into ileum dominant (isolated ileal and ileocolonic) and isolated colonic disease. This may allow for a more optimized approach to clinical care and scientific research for CD.

A molecular biomarker for prediction of clinical outcome in children with ASD, constipation, and intestinal inflammation

In children with autism spectrum disorder (ASD) who present to the gastroenterologist with chronic constipation on a background of colonic inflammation, we have identified two distinct clinical subtypes: (1) patients who experience a sustained state of GI symptomatic remission while on maintenance anti-inflammatory therapy (fast responders) and, (2) those with recurrent right-sided fecal loading requiring regular colon cleanouts during treatment for enterocolitis (slow responders). We hypothesized that a detailed molecular analysis of tissue from the affected region of the colon would provide mechanistic insights regarding the fast versus slow response to anti-inflammatory therapy. To test this, ascending colon biopsy tissues from 35 children with ASD (20 slow responders and 15 fast responders) were analyzed by RNAseq. Hierarchical cluster analysis was performed to assign samples to clusters and gene expression analysis was performed to identify differentially expressed transcripts (DETs) between samples within the clusters. Significant differences were found between the two clusters with fast responder-predominant cluster showing an upregulation of transcripts involved in the activation of immune and inflammatory response and the slow responder-predominant cluster showing significant over-representation of pathways impacting colonic motility (e.g. genes involved in tryptophan and serotonin degradation and mitochondrial dysfunction). Regression analysis identified a single long non-coding RNA that could predict cluster assignment with a high specificity (0.88), sensitivity (0.89) and accuracy (0.89). Comparison of gene expression profiles in the ascending colon from a subset of patients with ASD, chronic right-sided fecal loading constipation and a slow versus fast response to therapy has identified molecular mechanisms that likely contribute to this differential response following the primary therapeutic intervention (i.e. treatment for colonic inflammation with brief induction immunosuppression followed by maintenance non-steroidal anti-inflammatory therapy). Importantly, we have identified a transcript that, if validated, may provide a biomarker that can predict from the outset which patients will be slow responders who would benefit from an alternate therapeutic strategy in treating their constipation.

IL-12, IL-23 and IL-17 in IBD: immunobiology and therapeutic targeting

IL-12 and IL-23 are closely related cytokines with important roles in the regulation of tissue inflammation. Converging evidence from studies in mice, human observational studies and population genetics supports the importance of these cytokines in the regulation of mucosal inflammation in the gut in particular. Ustekinumab, a therapeutic antibody targeting both cytokines is now widely licensed for the treatment of Crohn's disease, including in Europe, the USA, Canada and Japan, whilst agents targeting IL-23 specifically are in late-phase clinical trials. We review the emerging understanding of the biology of IL-12 and IL-23, as well as that of their major downstream cytokines, including IL-17. In particular, we discuss how their biology has influenced the development of clinical trials and therapeutic strategies in IBD, as well as how findings from clinical trials, at times surprising, have in turn refocused our understanding of the underlying biology.

Engineered and wild-type L. lactis promote anti-inflammatory cytokine signalling in inflammatory bowel disease patient's mucosa

Dysbiosis of intestinal microbiota and aberrant inflammatory responses in gastrointestinal mucosa plays important roles in the development of inflammatory bowel disease (IBD). The purpose of this study was to demonstrate the probiotic activity of Lactococcus lactis and the ability of TNF-α-binding by recombinant L. lactis bearing TNF-α-binding affibodies. Various concentrations of recombinant L. lactis were exposed to TNF-α and its binding measured by ELISA. Mucosal biopsies of patients with active IBD were incubated with various L. lactis strains or E. coli DH5α strain and concentrations of TNF-α, IL-23, and IL-10 in the supernatants determined by ELISA. Recombinant L. lactis, at 1 × 10⁹ and 1 × 10⁸ CFU/mL, bound 22.6% and 18.4%, respectively of TNF-α (p < 0.05). When IBD-mucosa was incubated with any L. lactis strain at 1 × 10⁹ CFU/mL, levels of TNF-α and IL-23 were significantly decreased and that of IL-10 increased relative to that for the sterile culture. Opposite trends were observed with E. coli cultures. Recombinant L. lactis at 1 × 10⁸ CFU/mL bound as much as 62.8% (p = 0.026) of TNF-α in IBD-mucosa supernatants compared with the control strain. L. lactis strains are reported, for the first time, to induce an ex vivo anti-inflammatory cytokine profile in IBD inflamed mucosa. L. lactis could therefore constitute a promising alternative approach for treating IBD.

Pediatric Crohn disease is characterized by Th1 in the terminal ileum and Th1/Th17 immune response in the colon

The aim of this study was to assess the expression of inflammatory mediators in the affected terminal ileum and colon in pediatric Crohn disease (CD) patients with different stages of disease. Additionally, we assessed the role of efflux transporters in disease pathogenesis and their correlation with immune response. The study included 26 CD patients (10 newly diagnosed (CD-new), 8 CD-treated, and 8 CD-remission) and 15 control subjects. The terminal ileum IFN-γ, IL-6, and IL-1β were elevated in CD-new, while in the colon, the IFN-γ, IL-17A, and IL-6 were elevated in both CD-new and CD-treated subgroups. SOCS3 expression was elevated in both subgroups with active inflammation at both ileum and colon, while SOCS1 was elevated only in CD-new ileum and CD-treated colon. MDR1 expression in ileum was reduced in both subgroups with active inflammation, while BCRP was reduced only in CD-new subgroup.

CONCLUSION

New onset pediatric CD is characterized by Th1 response in ileum and mixed Th1/Th17 response in the colon, with elevated expressions of innate IL-6 and IL-1β. SOCS1/SOCS3 expressions seem to be insufficient for the regulation of the immune response. The reduction in MDR1 expression points to its role in the disease pathogenesis. What is Known: • CD is characterized by an aberrant immune response What is New: • The immune response in new onset pediatric CD differs between terminal ileum and colon • MDR1 expression is downregulated at both terminal ileum and colon irrespective of the disease activity.

Cytokine production profile in intestinal mucosa of paediatric inflammatory bowel disease

In the recent years, the incidence of inflammatory bowel disease (IBD) has dramatically increased in young subjects, however, the pathogenesis of paediatric IBD is poorly investigated. In this study we aimed to evaluate the cytokine pattern and the phenotype of cytokine producing cells in the intestinal mucosa of paediatric patients affected by Crohn’s disease (CD) or ulcerative colitis (UC) and of non-IBD healthy controls (HC). Cytokine (IL-15, TNF-α, INF-γ) production was analyzed at basal condition and after mitogen stimulation either intracellularly by flow cytometry or in intestinal cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). A higher frequency of enterocytes (EpCam+ cells) was observed in UC patients compared to CD or HC. An expansion of enterocytes producing IL-15 and TNF-α were found in IBD patients compared to HC. A marked expression of IL-15 in the intestinal epithelium of IBD patients was further confirmed by immunohistochemistry. Myeloid dendritic (CD11c+) cells producing TNF-α and INF-γ were increased in IBD biopsies. Unexpectedly, only after a strong mitogen stimulus, as phytohaemagglutinin, the frequency of CD3+ cells producing IFN-γ was increased in IBD compared to control intestinal mucosa. Interestingly, functional studies performed on organ cultures of intestinal biopsies with neutralizing anti-IL-15 monoclonal antibody showed a marked reduction of mononuclear cell activation, proliferation of crypt enterocytes, as well as a reduction of TNF-α release in organ culture supernatants. In conclusion, we found that in the gut mucosa of IBD children both enterocytes and dendritic cells produce proinflammatory cytokines. The over-expression of IL-15 by enterocytes in IBD intestine and the reduced IBD inflammation by IL-15 blockage suggests that this cytokine could be a therapeutic target in IBD.

Comparison of Cytokine and Efflux Transporter Expression in Pediatric Versus Adult-onset Ulcerative Colitis

OBJECTIVES

Ulcerative colitis (UC), a chronic inflammation of the colon, is often more severe in children than adults. Identification of altered expression of efflux transporters, cytokines, and suppressor of cytokine signaling (SOCS) molecules in pediatric versus adult patients could provide insight into the differential molecular patterns related to the age and disease pathology.

METHODS

Mucosal samples from terminal ileum and colon in pediatric (9 UC-New, 4 UC-Remission) and adult (9 UC-New, 8 UC-Remission) patients were compared with healthy subjects (15 children and 10 adults) for mRNA expressions of several efflux transporters, cytokines, and SOCS molecules.

RESULTS

The inflamed colon interleukin (IL)-6, IL-17A, and interferon-γ levels were elevated in UC-New subgroups but close to control values in UC-Remission. IL-1β expression was increased only in UC-New children. Interestingly, uninflamed ileum also showed increased IL-6 and IL-1β levels in UC-New subgroups. SOCS1/SOCS3 expression pattern followed a trend observed for inflammatory cytokines only in children. Both children and adults had decreased multidrug resistance protein 1 expression in colon, which inversely correlated with disease score, IL-6 and interferon-γ levels in UC-New children. IL-2 expression was upregulated in UC-Remission, compared with controls.

CONCLUSIONS

Efflux transporter expression varies between UC children and adults except for decreased multidrug resistance protein 1. UC is characterized by a dysregulated TH1 and TH17 cytokine response irrespective of age at disease onset, with higher cytokine levels detected in children. Increased IL-2 levels in remission imply a protective role for regulatory T cells (Tregs).

Mucosal Expression of Type 2 and Type 17 Immune Response Genes Distinguishes Ulcerative Colitis From Colon-Only Crohn's Disease in Treatment-Naive Pediatric Patients

BACKGROUND & AIMS

There is controversy regarding the role of the type 2 immune response in the pathogenesis of ulcerative colitis (UC)-few data are available from treatment-naive patients. We investigated whether genes associated with a type 2 immune response in the intestinal mucosa are up-regulated in treatment-naive pediatric patients with UC compared with patients with Crohn's disease (CD)-associated colitis or without inflammatory bowel disease (IBD), and whether expression levels are associated with clinical outcomes.

METHODS

We used a real-time reverse-transcription quantitative polymerase chain reaction array to analyze messenger RNA (mRNA) expression patterns in rectal mucosal samples from 138 treatment-naive pediatric patients with IBD and macroscopic rectal disease, as well as those from 49 children without IBD (controls), enrolled in a multicenter prospective observational study from 2008 to 2012. Results were validated in real-time reverse-transcription quantitative polymerase chain reaction analyses of rectal RNA from an independent cohort of 34 pediatric patients with IBD and macroscopic rectal disease and 17 controls from Cincinnati Children's Hospital Medical Center.

RESULTS

We measured significant increases in mRNAs associated with a type 2 immune response (interleukin [IL]5 gene, IL13, and IL13RA2) and a type 17 immune response (IL17A and IL23) in mucosal samples from patients with UC compared with patients with colon-only CD. In a regression model, increased expression of IL5 and IL17A mRNAs distinguished patients with UC from patients with colon-only CD (P = .001; area under the receiver operating characteristic curve, 0.72). We identified a gene expression pattern in rectal tissues of patients with UC, characterized by detection of IL13 mRNA, that predicted clinical response to therapy after 6 months (odds ratio [OR], 6.469; 95% confidence interval [CI], 1.553-26.94), clinical response after 12 months (OR, 6.125; 95% CI, 1.330-28.22), and remission after 12 months (OR, 5.333; 95% CI, 1.132-25.12).

CONCLUSIONS

In an analysis of rectal tissues from treatment-naive pediatric patients with IBD, we observed activation of a type 2 immune response during the early course of UC. We were able to distinguish patients with UC from those with colon-only CD based on increased mucosal expression of genes that mediate type 2 and type 17 immune responses. Increased expression at diagnosis of genes that mediate a type 2 immune response is associated with response to therapy and remission in pediatric patients with UC.

Assessment of disease activity in pediatric ulcerative colitis

To date, we encounter more and more pediatric patients with ulcerative colitis (UC). For yet unclear reasons, UC in pediatric patients seems to be a more aggressive and extensive disease than in their adult counterparts. In the majority of pediatric patients, the disease presents as pancolitis. The severity of the disease is reflected in the high use of corticosteroids and immunosuppressants and a high rate of surgery for medically refractory patients. The means by which to assess disease activity or to accurately predict its course are far from optimal. This review summarizes the current knowledge on the means for assessing UC activity in children. Research for developing new tools by which to monitor and forecast disease activity, are needed in all areas including invasive endoscopy, clinical evaluation, and treatment follow-up.

Regional Specialisation of T Cell Subsets and Apoptosis in the Human Gut Mucosa: Differences Between Ileum and Colon in Healthy Intestine and Inflammatory Bowel Diseases

BACKGROUND AND AIMS

There is very limited information regarding region-specific immunological response in human intestine. We aimed to determine differences in immune compartmentalisation between ileum and colon in healthy and inflamed mucosa.

METHODS

T cell profile and its apoptosis were measured by flow cytometry, Th1, Th17, Treg [CD4(+)CD25(+)FOXP3(+)], double positive [DP, CD3(+)CD4(+)CD8(+)] and double negative T cells [DN, CD3(+)CD4(-)CD8(-)], immunohistochemistry [FOXP3, caspase-3], and real-time polymerase chain reaction [PCR] [IFN-γ, IL-17-A, and FOXP3] on biopsies from different regions of healthy intestine and of intestine in inflammatory bowel diseases.

RESULTS

Healthy colon showed higher percentages of Treg, Th17, and DN, and lower numbers of DP T cells compared with ileum [p < 0.05]. Some but not all region-specific differences were lost in inflammatory conditions. Disease-specific patterns were found: a Th1/Th17 pattern and a Th17 pattern in Crohn's disease and ulcerative colitis respectively, whereas a reduction in Th1/Th17 was found in microscopic colitis. In colonic Crohn's disease and microscopic colitis, DN T cells had a pattern inverse to that of Th1/Th17 (increase in microscopic colitis [p < 0.05] and decrease in Crohn's disease [p < 0.005]). Higher levels of lymphocyte apoptosis were found in healthy colon compared with the ileal counterparts [p = 0.001]. All forms of colonic inflammation presented a dramatic decrease in apoptosis compared with healthy colon. By contrast ileal Crohn's disease showed higher levels of cleaved-Caspase(+) CD3(+) cells.

CONCLUSIONS

Immunological differences exist in healthy gastrointestinal tract. Inflammatory processes overwhelm some location-specific differences, whereas others are maintained. Care has to be taken when analysing immune response in intestinal inflammation, as location-specific differences may be relevant.

Obeticholic acid reduces bacterial translocation and inhibits intestinal inflammation in cirrhotic rats

BACKGROUND & AIMS

In advanced cirrhosis, gut bacterial translocation is the consequence of intestinal barrier disruption and leads to bacterial infection. Bile acid abnormalities in cirrhosis could play a role in the integrity of the intestinal barrier and the control of microbiota, mainly through the farnesoid X receptor. We investigated the long-term effects of the farnesoid X receptor agonist, obeticholic acid, on gut bacterial translocation, intestinal microbiota composition, barrier integrity and inflammation in rats with CCl4-induced cirrhosis with ascites.

METHODS

Cirrhotic rats received a 2-week course of obeticholic acid or vehicle starting once ascites developed. We then determined: bacterial translocation by mesenteric lymph node culture, ileum expression of antimicrobial peptides and tight junction proteins by qPCR, fecal albumin loss, enteric bacterial load and microbiota composition by qPCR and pyrosequencing of ileum mucosa-attached contents, and intestinal inflammation by cytometry of the inflammatory infiltrate.

RESULTS

Obeticholic acid reduced bacterial translocation from 78.3% to 33.3% (p<0.01) and upregulated the expression of the farnesoid X receptor-associated gene small heterodimer partner. Treatment improved ileum expression of antimicrobial peptides, angiogenin-1 and alpha-5-defensin, tight junction proteins zonulin-1 and occludin, and reduced fecal albumin loss and liver fibrosis. Enteric bacterial load normalized, and the distinctive mucosal microbiota of cirrhosis was reduced. Gut immune cell infiltration was reduced and inflammatory cytokine and Toll-like receptor 4 expression normalized.

CONCLUSIONS

In ascitic cirrhotic rats, obeticholic acid reduces gut bacterial translocation via several complementary mechanisms at the intestinal level. This agent could be used as an alternative to antibiotics to prevent bacterial infection in cirrhosis.

Mean Platelet Volume in Crohn's Disease Patients Predicts Sustained Response to a 52-Week Infliximab Therapy: A Pilot Study

BACKGROUND

The loss of response to infliximab in Crohn's disease (CD) patients is currently a major clinical problem. Recently, mean platelet volume (MPV) has been proposed as a new biomarker of CD activity. Here, we hypothesized that MPV may be used as cheap and efficient biomarker of subclinical inflammation during 52-week therapy in CD patients responding to infliximab induction treatment.

AIMS

The aim of study was to establish whether MPV at baseline and pre-infusion at week 14 are good predictors of sustained response after week 14 in CD patients undergoing 52-week infliximab therapy.

METHODS

A retrospective study of 30 adult CD patients who underwent a 52-week course of treatment with infliximab and achieved response at week 14 to induction treatment was performed. The association between MPV, baseline disease parameters and maintained clinical response or remission during infliximab therapy was assessed.

RESULTS

Higher MPV at week 14 was observed in CD patients with sustained response to infliximab after week 14 than in patients with loss of response (p = 0.0019). In patients with loss of response to maintenance infliximab treatment, lower ΔMPV between baseline and week 14 was calculated (p = 0.0003). MPV > 10.3 fl at week 14 predicts sustained response with 67 % sensitivity and 80 % specificity. ΔMPV between baseline and week 14 >0.4 fl predicts sustained response with 87 % sensitivity and 93 % specificity.

CONCLUSION

MPV at week 14 and ΔMPV between baseline and week 14 are good predictors of sustained response to infliximab maintenance treatment in CD patients.

Host response mechanisms in periodontal diseases

Periodontal diseases usually refer to common inflammatory disorders known as gingivitis and periodontitis, which are caused by a pathogenic microbiota in the subgingival biofilm, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia and Treponema denticola that trigger innate, inflammatory, and adaptive immune responses. These processes result in the destruction of the tissues surrounding and supporting the teeth, and eventually in tissue, bone and finally, tooth loss. The innate immune response constitutes a homeostatic system, which is the first line of defense, and is able to recognize invading microorganisms as non-self, triggering immune responses to eliminate them. In addition to the innate immunity, adaptive immunity cells and characteristic cytokines have been described as important players in the periodontal disease pathogenesis scenario, with a special attention to CD4⁺ T-cells (T-helper cells). Interestingly, the T cell-mediated adaptive immunity development is highly dependent on innate immunity-associated antigen presenting cells, which after antigen capture undergo into a maturation process and migrate towards the lymph nodes, where they produce distinct patterns of cytokines that will contribute to the subsequent polarization and activation of specific T CD4+ lymphocytes. Skeletal homeostasis depends on a dynamic balance between the activities of the bone-forming osteoblasts (OBLs) and bone-resorbing osteoclasts (OCLs). This balance is tightly controlled by various regulatory systems, such as the endocrine system, and is influenced by the immune system, an osteoimmunological regulation depending on lymphocyte- and macrophage-derived cytokines. All these cytokines and inflammatory mediators are capable of acting alone or in concert, to stimulate periodontal breakdown and collagen destruction via tissue-derived matrix metalloproteinases, a characterization of the progression of periodontitis as a stage that presents a significantly host immune and inflammatory response to the microbial challenge that determine of susceptibility to develop the destructive/progressive periodontitis under the influence of multiple behavioral, environmental and genetic factors.

Aedes aegypti salivary gland extract ameliorates experimental inflammatory bowel disease

Current therapies for inflammatory bowel disease (IBD) are not totally effective, resulting in persistent and recurrent disease for many patients. Mosquito saliva contains immunomodulatory molecules and therein could represent a novel therapy for IBD. Here, we demonstrated the therapeutic activity of salivary gland extract (SGE) of Aedes aegypti on dextran sulfate sodium (DSS)-induced colitis. For this purpose, C57BL/6 male mice were exposed to 3% DSS in drinking water and treated with SGE at early (days 3-5) or late (days 5-8) time points, followed by euthanasia on days 6 and 9, respectively, for sample collection. The results showed an improvement in clinical disease outcome and postmortem scores after SGE treatment, accompanied by the systemic reduction in peripheral blood lymphocytes, with no impact on bone marrow and mesenteric lymph nodes cellularity or macrophages toxicity. Moreover, a local diminishment of IFN-γ, TNF-α, IL-1β and IL-5 cytokines together with a reduction in the inflammatory area were observed in the colon of SGE-treated mice. Strikingly, early treatment with SGE led to mice protection from a late DSS re-challenging, as observed by decreased clinical and postmortem scores, besides reduced circulating lymphocytes, indicating that the mosquito saliva may present components able to prevent disease relapse. Indeed, high performance liquid chromatography (HPLC) experiments pointed to a major SGE pool fraction (F3) able to ameliorate disease signs. In conclusion, SGE and its components might represent a source of important immunomodulatory molecules with promising therapeutic activity for IBD.

Central muscarinic cholinergic activation alters interaction between splenic dendritic cell and CD4+CD25- T cells in experimental colitis

BACKGROUND

The cholinergic anti-inflammatory pathway (CAP) is based on vagus nerve (VN) activity that regulates macrophage and dendritic cell responses in the spleen through alpha-7 nicotinic acetylcholine receptor (a7nAChR) signaling. Inflammatory bowel disease (IBD) patients present dysautonomia with decreased vagus nerve activity, dendritic cell and T cell over-activation. The aim of this study was to investigate whether central activation of the CAP alters the function of dendritic cells (DCs) and sequential CD4+/CD25-T cell activation in the context of experimental colitis.

METHODS

The dinitrobenzene sulfonic acid model of experimental colitis in C57BL/6 mice was used. Central, intracerebroventricular infusion of the M1 muscarinic acetylcholine receptor agonist McN-A-343 was used to activate CAP and vagus nerve and/or splenic nerve transection were performed. In addition, the role of α7nAChR signaling and the NF-kB pathway was studied. Serum amyloid protein (SAP)-A, colonic tissue cytokines, IL-12p70 and IL-23 in isolated splenic DCs, and cytokines levels in DC-CD4+CD25-T cell co-culture were determined.

RESULTS

McN-A-343 treatment reduced colonic inflammation associated with decreased pro-inflammatory Th1/Th17 colonic and splenic cytokine secretion. Splenic DCs cytokine release was modulated through α7nAChR and the NF-kB signaling pathways. Cholinergic activation resulted in decreased CD4+CD25-T cell priming. The anti-inflammatory efficacy of central cholinergic activation was abolished in mice with vagotomy or splenic neurectomy.

CONCLUSIONS

Suppression of splenic immune cell activation and altered interaction between DCs and T cells are important aspects of the beneficial effect of brain activation of the CAP in experimental colitis. These findings may lead to improved therapeutic strategies in the treatment of IBD.

Association among genetic predisposition, gut microbiota, and host immune response in the etiopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a chronic disorder that affects thousands of people around the world. These diseases are characterized by exacerbated uncontrolled intestinal inflammation that leads to poor quality of life in affected patients. Although the exact cause of IBD still remains unknown, compelling evidence suggests that the interplay among immune deregulation, environmental factors, and genetic polymorphisms contributes to the multifactorial nature of the disease. Therefore, in this review we present classical and novel findings regarding IBD etiopathogenesis. Considering the genetic causes of the diseases, alterations in about 100 genes or allelic variants, most of them in components of the immune system, have been related to IBD susceptibility. Dysbiosis of the intestinal microbiota also plays a role in the initiation or perpetuation of gut inflammation, which develops under altered or impaired immune responses. In this context, unbalanced innate and especially adaptive immunity has been considered one of the major contributing factors to IBD development, with the involvement of the Th1, Th2, and Th17 effector population in addition to impaired regulatory responses in CD or UC. Finally, an understanding of the interplay among pathogenic triggers of IBD will improve knowledge about the immunological mechanisms of gut inflammation, thus providing novel tools for IBD control.

Cytokines in inflammatory bowel disease

Cytokines have a crucial role in the pathogenesis of inflammatory bowel diseases (IBDs), such as Crohn's disease and ulcerative colitis, where they control multiple aspects of the inflammatory response. In particular, the imbalance between pro-inflammatory and anti-inflammatory cytokines that occurs in IBD impedes the resolution of inflammation and instead leads to disease perpetuation and tissue destruction. Recent studies suggest the existence of a network of regulatory cytokines that has important implications for disease progression. In this Review, we discuss the role of cytokines produced by innate and adaptive immune cells, as well as their relevance to the future therapy of IBD.