Relationship of functional and antigenic interleukin 6 to disease activity in inflammatory bowel disease

Hippuric acid alleviates dextran sulfate sodium-induced colitis via suppressing inflammatory activity and modulating gut microbiota

Inflammatory bowel disease (IBD) is a chronic inflammatory disease associated with metabolic disorder and gut dysbiosis. Decreased abundance of hippuric acid (HA) was found in patients with IBD. HA, metabolized directly from benzoic acid in the intestine and indirectly from polyphenols, serves as a marker of polyphenol catabolism. While polyphenols and benzoic acid have been shown to alleviate intestinal inflammation, the role of HA in this context remains unknown. Herein, we investigated the effects and mechanism of HA on DSS-induced colitis mice. The results revealed that HA alleviated clinical activity and intestinal barrier damage, decreased pro-inflammatory cytokine production. Metagenomic sequencing suggested that HA treatment restored the gut microbiota, including an increase in beneficial gut bacteria such as Adlercreutzia, Eubacterium, Schaedlerella and Bifidobacterium_pseudolongum. Furthermore, we identified 113 candidate genes associated with IBD that are potentially under HA regulation through network pharmacological analyses. 10 hub genes including ALB, IL-6, HSP90AA1, and others were identified using PPI analysis and validated using molecular docking and mRNA expression analysis. Additionally, KEGG analysis suggested that the renin-angiotensin system (RAS), NF-κB signaling and Rap1 signaling pathways were important pathways in the response of HA to colitis. Thus, HA may provide novel biotherapy options for IBD.

Cytokines of the interleukin-6 family as emerging targets in inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD) is an umbrella term that includes different chronic inflammatory diseases of the gastrointestinal tract, most commonly Crohn's disease and ulcerative colitis. IBD affects more than 6 million people worldwide and constitutes not only a debilitating disease for the patients, but also a significant factor for society due to costs for health care and reduced working capacity. Despite the introduction of biologicals for the treatment of IBD, the identification of novel targets that could lead to novel therapeutics is still needed.

AREAS COVERED

In this review, we summarize current knowledge about the interleukin-6 family of cytokines as potential therapeutic targets for improving the therapy of patients with IBD. We discuss cytokines like IL-6 itself for which therapeutics such as inhibitory monoclonal antibodies have already entered the clinics, but also focus on other family members whose therapeutic potential has not been explored yet.

EXPERT OPINION

The different cytokines of the IL-6 family offer multiple therapeutic targets that can potentially be used to treat patients with inflammatory bowel disease, but unwanted side effects like inhibition of epithelial regeneration have to be considered.

Serum Interleukin 6, Controlling Nutritional Status (CONUT) Score and Phase Angle in Patients with Crohn's Disease

Crohn's disease (CD) is a chronic inflammatory disorder that may occur in any segment of the gastrointestinal tract. Asymptomatic or untreated inflammation along with malnutrition can often coexist in patients with CD, impairing clinical outcomes, therefore the aim of this study was to assess the relationship between inflammation, malnutrition risk and nutritional status in CD patients. Consecutive adult CD outpatients aged 18-65 years were recruited. Disease activity was clinically defined by the Crohn's Disease Activity Index (CDAI), whilst anthropometry and phase angle (PhA) were measured. The Controlling Nutritional Status (CONUT) score was retrospectively calculated for screening malnutrition risk and blood samples were taken. A total of 140 CD patients with a mean age of 38.8 ± 13.9 years and an average weight of 64.9 ± 12.0 kg were included. Serum interleukin (IL)-6 concentration was increased in active-CD patients, unrelated to medical treatment, which was associated with CDAI and PhA. Based on the CONUT score, the prevalence of patients with moderate/severe malnutrition risk (score ≥ 5) was 10%, showing lower age, body mass index and fat mass, but higher IL-6 and IL-1β levels than subjects classified as not at risk (score 0-1). Finally, increased IL-6 levels and reduced PhA values were identified as independent predictors of moderate/severe malnutrition risk (p < 0.05). In conclusion, IL-6 increased in active-CD patients, which was inversely correlated with PhA. Although the CONUT score might be helpful for identifying CD patients at moderate/severe risk of malnutrition, larger studies are needed to verify these results in different settings.

Relationships of circulating CD4+ T cell subsets and cytokines with the risk of relapse in patients with Crohn’s disease

Background and aims

We aimed to analyze circulating CD4+ T cell subsets and cytokines during the course of Crohn’s disease (CD).

Methods and results

CD4+ T cell subsets, ultrasensitive C-reactive protein (usCRP), and various serum cytokines (IL-6, IL-8, IL-10, IL-13, IL-17A, IL-23, TNFα, IFNγ, and TGFβ) were prospectively monitored every 3 months for 1 year, using multicolor flow cytometry and an ultrasensitive Erenna method in CD patients in remission at inclusion. Relapse occurred in 35 out of the 113 consecutive patients (31%). For patients in remission within 4 months prior to relapse and at the time of relapse, there was no significant difference in Th1, Th17, Treg, and double-positive CD4+ T cell subsets co-expressing either IFNγ and FOXP3, IL-17A and FOXP3, or IFNγ and IL-17A. On the contrary, in patients who remained in remission, the mean frequency and number of double-positive IL-17A+FOXP3+ CD4+ T cells and the level of usCRP were significantly higher (p ≤ 0.01) 1 to 4 months prior to relapse. At the time of relapse, only the IL-6 and usCRP levels were significantly higher (p ≤ 0.001) compared with those patients in remission. On multivariate analysis, a high number of double-positive IL-17A+FOXP3+ CD4+ T cells (≥1.4 cells/mm3) and elevated serum usCRP (≥3.44 mg/L) were two independent factors associated with risk of relapse.

Conclusions

Detection of circulating double-positive FOXP3+IL-17A+ CD4+ T cell subsets supports that T cell plasticity may reflect the inflammatory context of Crohn’s disease. Whether this subset contributes to the pathogenesis of CD relapse needs further studies.

Exclusive inhibition of IL-6 trans-signaling by soluble gp130FlyRFc

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A variety of sgp130Fc muteins was generated.

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Introduction of a gp130 SNP (R281Q) into sgp130Fc increases IL-6 specificity.

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The sgp130Fc variant sgp130^FlyR exclusively affects IL-6 trans-signaling.

gp130 is the signal-transducing receptor for the Interleukin (IL)-6 type cytokines IL-6 and IL-11. To induce signaling, IL-6 forms a complex with IL-6 receptor (IL-6R) and IL-11 with IL-11 receptor (IL-11R). Membrane-bound IL-6R and IL-11R in complex with gp130 and the cytokine mediate classic-signaling, whereas trans-signaling needs soluble IL-6R and IL-11R variants. Interleukin (IL)-6 trans-signaling is of particular importance because it drives the development of autoimmune diseases, including rheumatoid arthritis and chronic inflammatory bowel diseases, whereas a role for IL-11 trans-signaling remains elusive. Soluble gp130 selectively inhibits trans-signaling of IL-6 whereas both, classic- and trans-signaling are abrogated by IL-6- and IL-6R-antibodies. Recently, we described an optimized sgp130 variant, which carries three amino acid substitutions T102Y/Q113F/N114L (sgp130^FlyFc) resulting in reduced inhibition of IL-11 trans-signaling by increasing the affinity of sgp130 for the site I of IL-6. Moreover, we described that the patient mutation R281Q in gp130 results in reduced IL-11 signaling. Here, we show that the combination of T102Y/Q113F/N114L and R281Q in the new variant sgp130^FlyRFc results in complete preservation of IL-11 mediated trans-signaling, whereas inhibition of IL-6 trans-signaling is maintained. Since sgp130Fc (olamkicept) has successfully completed a phase IIa trial in Crohn’s disease (CD) and ulcerative colitis, sgp130^FlyRFc might serve as second-generation therapeutic to diminish IL-11 trans-signaling cross-reactivity.

Utilization of physiologically-based pharmacokinetic model to assess disease-mediated therapeutic protein-disease-drug interaction in immune-mediated inflammatory diseases

It is known that interleukin-6 (IL-6) can significantly modulate some key drug-metabolizing enzymes, such as phase I cytochrome P450s (CYPs). In this study, a physiologically-based pharmacokinetic (PBPK) model was developed to assess CYPs mediated therapeutic protein drug interactions (TP-DIs) in patients with immune-mediated inflammatory diseases (IMIDs) with elevated systemic IL-6 levels when treated by anti-IL-6 therapies. Literature data of IL-6 levels in various diseases were incorporated in SimCYP to construct respective virtual patient populations. The modulation effects of systemic IL-6 level and local IL-6 level in the gastrointestinal tract (GI) on CYPs activities were assessed. Upon blockade of the IL-6 signaling pathway by an anti-IL-6 treatment, the area under plasma concentration versus time curves (AUCs) of S-warfarin, omeprazole, and midazolam were predicted to decrease by up to 40%, 42%, and 46%, respectively. In patients with Crohn's disease and ulcerative colitis treated with an anti-IL-6 therapy, the lowering of the elevated IL-6 levels in the local GI tissue were predicted to result in further decreases in AUCs of those CYP substrates. The propensity of TP-DIs under comorbidity conditions, such as in patients with cancer with IMID, were also explored. With further validation with relevant clinical data, this PBPK model may provide an in silico way to quantify the magnitude of potential TP-DI in patients with elevated IL-6 levels when an anti-IL-6 therapeutic is used with concomitant small-molecule drugs. This model may be further adapted to evaluate the CYP modulation effect by other therapeutic modalities, which would significantly alter levels of proinflammatory cytokines during the treatment period.

Selective inhibition of IL-6 trans-signaling by a miniaturized, optimized chimeric soluble gp130 inhibits TH17 cell expansion

The cytokine interleukin-6 (IL-6) signals through three mechanisms called classic signaling, trans-signaling, and trans-presentation. IL-6 trans-signaling is distinctly mediated through a soluble form of its transmembrane receptor IL-6R (sIL-6R) and the coreceptor gp130 and is implicated in multiple autoimmune diseases. Although a soluble form of gp130 (sgp130) inhibits only IL-6 trans-signaling, it also blocks an analogous trans-signaling mechanism of IL-11 and its soluble receptor sIL-11R. Here, we report miniaturized chimeric soluble gp130 variants that efficiently trap IL-6:sIL-6R but not IL-11:sIL-11R complexes. We designed a novel IL-6 trans-signaling trap by fusing a miniaturized sgp130 variant to an IL-6:sIL-6R complex-binding nanobody and the Fc portion of immunoglobulin G (IgG). This trap, called cs-130Fc, exhibited improved inhibition of as well as increased selectivity for IL-6 trans-signaling compared to the conventional fusion protein sgp130Fc. We introduced affinity-enhancing mutations in cs-130Fc and sgp130Fc that further improved selectivity toward IL-6 trans-signaling. Moreover, cs-130Fc efficiently inhibited the expansion of T helper 17 (TH17) cells in cultures of mouse CD4+ T cells treated with IL-6:sIL-6R. Thus, these variants may provide or lead to the development of more precisely targeted therapeutics for inflammatory disorders associated with IL-6 trans-signaling.

Estrogen-related receptor alpha (ERRα) is a key regulator of intestinal homeostasis and protects against colitis

The estrogen-related receptor alpha (ERRα) is a primary regulator of mitochondrial energy metabolism, function and dynamics, and has been implicated in autophagy and immune regulation. ERRα is abundantly expressed in the intestine and in cells of the immune system. However, its role in inflammatory bowel disease (IBD) remains unknown. Here, we report a protective role of ERRα in the intestine. We found that mice deficient in ERRα were susceptible to experimental colitis, exhibiting increased colon inflammation and tissue damage. This phenotype was mediated by impaired compensatory proliferation of intestinal epithelial cells (IEC) following injury, enhanced IEC apoptosis and necrosis and reduced mucus-producing goblet cell counts. Longitudinal analysis of the microbiota demonstrated that loss of ERRα lead to a reduction in microbiome α-diversity and depletion of healthy gut bacterial constituents. Mechanistically, ERRα mediated its protective effects by acting within the radio-resistant compartment of the intestine. It promoted disease tolerance through transcriptional control of key genes involved in intestinal tissue homeostasis and repair. These findings provide new insights on the role of ERRα in the gut and extends our current knowledge of nuclear receptors implicated in IBD.

Phytochemicals Targeting JAK-STAT Pathways in Inflammatory Bowel Disease: Insights from Animal Models

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract that consists of Crohn’s disease (CD) and ulcerative colitis (UC). Cytokines are thought to be key mediators of inflammation-mediated pathological processes of IBD. These cytokines play a crucial role through the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) signaling pathways. Several small molecules inhibiting JAK have been used in clinical trials, and one of them has been approved for IBD treatment. Many anti-inflammatory phytochemicals have been shown to have potential as new drugs for IBD treatment. This review describes the significance of the JAK–STAT pathway as a current therapeutic target for IBD and discusses the recent findings that phytochemicals can ameliorate disease symptoms by affecting the JAK–STAT pathway in vivo in IBD disease models. Thus, we suggest that phytochemicals modulating JAK–STAT pathways are potential candidates for developing new therapeutic drugs, alternative medicines, and nutraceutical agents for the treatment of IBD.

BODY IRON STATUS INDICATORS AND INFLAMMATION INDICATORS DURING INFLAMMATORY BOWEL DISEASE THERAPY IN CHILDREN AND ADOLESCENTES

BACKGROUND

The treatment of patients with inflammatory bowel disease (IBD) consists of the induction and maintenance remission of the disease. Iron status indicators would be useful for the diagnosis of iron deficiency anemia, whereas the inflammation indicators would be for the diagnosis of chronic disease anemia.

OBJECTIVE

To assess body iron status indicators and inflammation indicators during the treatment of IBD, consisted of conventional or infliximab therapy in children and adolescents.

METHODS

A case-control study of a sample of 116 individuals, of which 81 patients with IBD, 18 of them receiving conventional therapy, 20 infliximab therapy, and 43 who were in remission of the disease, and 35 healthy (control group) children and adolescents. Iron status and inflammation indicators were investigated at baseline, and 2 and 6 months of both therapies - conventional and infliximab.

RESULTS

The mean age was 12.1±4.3 years. At baseline, both groups - conventional therapy and infliximab - presented significant differences in most markers studied compared to the control group. After 2 months of conventional therapy, hemoglobin and serum iron levels were lower than those of the control group; and red cells distribution width (RDW), total iron-binding capacity, transferrin receptor/ferritin ratio, and interleukin-6 were higher than the control group. After 2 months of infliximab treatment, hemoglobin and serum iron levels were lower than those of the control group; and RDW, soluble transferrin receptor, soluble transferrin receptor/ferritin ratio, and interleukin-6 were higher than the control group. After 6 months of conventional therapy, hemoglobin and serum iron levels were lower than those of the control group, and RDW and interleukin-6 were higher than those of the control group. After 6 months of infliximab treatment, the hemoglobin and serum iron levels were lower than the control group, and RDW, soluble transferrin receptor, soluble transferrin receptor/ferritin ratio, erythrocyte sedimentation rate, and platelets were higher than the control group. Regarding patients under treatment for at least one year (remission group), all markers studied, except transferrin, were similar to the control group.

CONCLUSION

In conclusion, there were some contradictions among the different body iron status indicators and inflammation indicators at two and 6 months of treatment with conventional and infliximab therapy, however after one year of treatment, as shown by the remission group, all indicators studied, except transferrin, were similar to healthy children and adolescents.

Effects of Mesobiliverdin IXα-Enriched Microalgae Feed on Gut Health and Microbiota of Broilers

Gut inflammatory bowel diseases (IBDs) links to animal medicinal feed and antibiotic-resistance are fueling major economic impacts in the agricultural livestock industry. New animal feeds that promote livestock gut health and control of IBDs without antibiotics are needed. This study investigates the effects of mesobiliverdin IXα (MBV)-enriched microalgae spirulina extracts on the growth performance, blood parameters, intestinal morphology, and gut microbiota of broilers. A total of 288 1-day-old broiler chicks (Arbor Acres) were randomly allotted to six dietary treatments (4 pens/treatment and 12 birds/pen). The dietary treatments comprised a basal diet as control (CON), basal diet plus 0.05 and 0.1% microalgae extract as low and high dose, respectively (SP1 and SP2), basal diet plus 0.05 and 0.1% MBV-enriched microalgae extract as low and high dose, respectively (MBV-SP1 and MBV-SP2), and basal diet plus 0.1% amoxicillin (AMX). All treated animals showed no significant differences in live weight, average daily gain, and feed efficiency compared to control animals. Histological examination showed that AMX treatment decreased the villi lengths of the duodenum and ileum below control villi length (P < 0.05) while MBV-SP1 and particularly MBV-SP2 increased villi lengths in the duodenum, jejunum, and ileum above AMX -treatment lengths (P < 0.05). The Firmicutes/Bacteroidetes ratio increased in the cecum of broilers fed AMX (P < 0.05) while SP2, MBV-SP1, and MBV-SP2-fed animals showed (in order) increasing ratios up to the AMX level. The abundance of bacterial species of the genus Lactobacillus increased in MBV-SP1 and MBV-SP2-fed groups including a striking increase in Lactobacillus salivarius abundance with MBV-SP2 (P < 0.05). Feeding MBV-SP1 and MBV-SP2 decreased the level of pro-inflammatory cytokine IL-6 in plasma of broilers to a greater extent than SP1 and SP2. These results reveal that MBV-enriched microalgae extracts improve the intestinal health and beneficial microflora composition of broilers.

Increased Severity of Ulcerative Colitis in the Terminal Phase of the Metabolic Syndrome

Ulcerative colitis is chronic immune-mediated disorder that affects primarily colonic mucosa. The metabolic syndrome has increasing global prevalence with a significant impact on biology of chronic diseases, such as ulcerative colitis. Today it is known that the metabolic syndrome attenuates severity of ulcerative colitis. Still, there is no evidence that different stages of metabolic syndrome alter the course of the ulcerative colitis. The aim of this study was to dissect out how progression of the metabolic syndrome impacted the biology of ulcerative colitis and severity of clinical presentation. Seventy-two patients (41 men and 31 women, 22-81 years old) were enrolled in this observational cross-sectional study. Concentrations of pro- and anti-inflammatory cytokines in serum and feces samples were measured and phenotype of colon infiltrating cells was analyzed. Patients in the terminal phase of the metabolic syndrome have clinically and pathohistologically more severe form of ulcerative colitis, which is followed by decreased concentrations of systemic galectin-1, increased values of systemic pro-inflammatory mediators and increased influx of lymphocytes in affected colon tissue. Our data suggest that reduced concentrations of galectin-1 and predomination of the pro-inflammatory mediators in patients with terminal stage of the metabolic syndrome enhance local chronic inflammatory response and subsequent tissue damage, and together point on important role of galectin-1 in immune response in ulcerative colitis patients with the metabolic syndrome.

Myeloid-Derived IL-33 Limits the Severity of Dextran Sulfate Sodium-Induced Colitis

IL-33 is an IL-1 family cytokine that signals through its cognate receptor, ST2, to regulate inflammation. Whether IL-33 serves a pathogenic or protective role during inflammatory bowel disease is controversial. Herein, two different strains of cell-specific conditionally deficient mice were used to compare the role of myeloid- versus intestinal epithelial cell-derived IL-33 during dextran sodium sulfate-induced colitis. Data show that loss of CD11c-restricted IL-33 exacerbated tissue pathology, coinciding with increased tissue Il6 levels and loss of intestinal forkhead box p3⁺ regulatory T cells. Surprisingly, the lack of intestinal epithelial cell-derived IL-33 had no impact on disease severity or tissue recovery. Thus, we show that myeloid-derived IL-33 functionally restrains colitic disease, whereas intestinal epithelial cell-derived IL-33 is dispensable.

Effect of cigarette smoke extract on the intestinal microenvironment of ulcerative colitis tissue

Background and Aim

Ulcerative colitis (UC) is an autoimmune disease characterized by inflammation in the gastrointestinal tract. The severity of UC is higher in nonsmokers than smokers; however, the biological mechanisms controlling this effect remain unknown. The aim of this study was to examine the effect of cigarette smoke extract (CSE) on inflamed and noninflamed colonic tissue from UC patients and to determine if inflammatory mediators, transcription factors, and T cell phenotypes are altered by CSE.

Methods

Blood and colonic biopsies were obtained from UC patients undergoing endoscopy. Biopsies were cultured in the presence or absence of CSE. Multiplex enzyme‐linked immunosorbent assay (ELISA) measured secreted levels of inflammatory mediators. Nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) and Hypoxia‐inducible factor 1‐alpha (HIF‐1α) expression were measured by DNA‐binding ELISA. T cell phenotypes were assessed by flow cytometry in matched blood and biopsies.

Results

Secreted levels of interleukin 2 (IL‐2), interleukin 6 (IL‐6), tumor necrosis factor ‐ alpha (TNF‐α), chemokine (C‐C motif) ligand 2 (CCL2), and interleukin 10 (IL‐10) were significantly (all P < 0.05) decreased following treatment with CSE. This effect was specific to inflamed tissue and was not observed in noninflamed tissue. CSE did not alter the expression of NF‐κB or HIF‐1α. Assessment of T cell phenotypes in blood and tissue revealed that there were significantly more activated and exhausted T cells in the colonic tissue compared to matched blood. These profiles were not altered following CSE treatment.

Conclusion

These data suggest that observed effects of CSE in reducing inflammatory mediators ex vivo are specific to inflamed colonic tissue but are not due to the activation of NF‐κB or HIF‐1α and are not caused by alterations in subpopulations of T cells in these UC tissues.

Suppression of Inflammatory Cytokines Expression with Bitter Melon (Momordica Charantia) in TNBS-instigated Ulcerative Colitis

Background and Objective

This study was aimed to elucidate the molecular mechanism of Momordica charantia (MCh), along with a standard drug prednisolone, in a rat model of colitis induced by trinitrobenzene sulfonic acid (TNBS).

Methods

After the induction of the experimental colitis, the animals were treated with MCh (4 g/kg/day) for 14 consecutive days by intragastric gavage. The colonic tissue expression levels of C-C motif chemokine ligand 17 (CCL-17), interleukin (IL)-1β, IL-6, IL-23, interferon-γ (IFN-γ), nuclear factor kappa B (NF-kB), and tumor necrosis factor-α (TNF-α), were determined at both mRNA and protein levels to estimate the effect of MCh. Besides, colonic specimens were analyzed histopathologically after staining with hematoxylin and eosin.

Results

The body weights from TNBS-instigated colitis rats were found to be significantly lower than untreated animals. Also, the IFN-γ, IL-1β, IL-6, Il-23, TNF-α, CCL-17, and NF-kB mRNA and protein levels were increased significantly from 1.86-4.91-fold and 1.46-5.50-fold, respectively, in the TNBS-instigated colitis group as compared to the control. Both the MCh and prednisolone treatment significantly reduced the bodyweight loss. It also restored the induced colonic tissue levels of IL-1β, IL-6, IFN-γ, and TNF-α to normal levels seen in untreated animals. These results were also supported with the histochemical staining of the colonic tissues from both control and treated animals.

Conclusion

The presented data strongly suggests that MCh has the anti-inflammatory effect that might be modulated through vitamin D metabolism. It is the right candidate for the treatment of UC as an alternative and complementary therapeutics.

Cow and Human Milk-Derived Exosomes Ameliorate Colitis in DSS Murine Model

The aim of this study was to investigate the therapeutic effect of cow and human milk derived exosomes (MDEs) on colitis. We used gavage administration of fluorescent labeled MDEs to track their localization patterns in vivo and studied their therapeutic effect on colitis in a dextran sulfate sodium (DSS)-induced colitis model. MDEs attenuated the severity of colitis induced by DSS and statistically reduced the histopathological scoring grade and shortening of the colon. Likewise, treatment with MDEs reduced the expression of interleukin 6 and tumor necrosis factor-α. Moreover, miRNAs highly expressed in milk, such as miRNA-320, 375, and Let-7, were found to be more abundant in the colon of MDE-treated mice compared with untreated mice; contrastingly, the expression of their target genes, mainly DNA methyltransferase 1 (DNMT1) and DNMT3 were downregulated. Furthermore, the level of TGF-β was upregulated in the colon of MDE-treated mice. We demonstrated that MDEs have a therapeutic and anti-inflammatory effect on colitis, involving several complementary pathways in its mechanism of action. The therapeutic effects of MDEs might have implications for the possible addition of MDEs as a nutrient in enteral nutrition formulas for patients with inflammatory bowel disease.

INTERACTIONS AMONG INTERLEUKIN-6, C-REACTIVE PROTEIN AND INTERLEUKIN-6 (-174) G/C POLYMORPHISM IN THE PATHOGENESIS OF CROHN'S DISEASE AND ULCERATIVE COLITIS

Inflammatory bowel diseases are multifactorial disorders the clinical manifestation of which depends on the interaction among immune response, genetic and environmental factors. There is growing evidence that cytokines and gene polymorphisms have an important role in disease pathogenesis in various populations although molecular mechanism of their signaling and interactions is not fully understood yet. The present study aimed at exploring the effects of interleukin-6, C-reactive protein and interleukin-6 rs1800795 polymorphism on the development of Crohn’s disease, ulcerative colitis and inflammatory bowel diseases overall and at determining differences between inflammatory bowel disease patients and healthy controls. A total of 132 inflammatory bowel disease patients and 71 healthy blood donors were investigated. In order to assess the clinical relevance of interleukin-6 and C-reactive protein serum concentration and interleukin-6 rs1800795 single nucleotide polymorphism in patients with Crohn’s disease and ulcerative colitis, we performed a cross-sectional, case-control study. Quantitative assessment of serum interleukin-6 and C-reactive protein was performed with solid-phase, enzyme-labeled, chemiluminescent sequential immunometric and immunoturbidimetric assay, respectively. A real-time fluorescence resonance energy transfer-based method on a LightCyclerTM PCR 1.2 was used for genotyping of IL-6 rs1800795 polymorphism. Both interleukin-6 and C-reactive protein serum levels were elevated in Crohn’s disease and ulcerative colitis patients. Positive correlations were observed between C-reactive protein and interleukin-6 serum concentration and ulcerative colitis activity index as measured by modified Truelove-Witt’s severity index scale. C-reactive protein serum level was higher in Crohn’s disease patients without intestinal resection than in Crohn’s disease patients with prior intestinal resection. In ulcerative colitis patients, interleukin-6 and C-reactive protein serum levels were statistically significantly higher in CC interleukin-6 genotype in comparison to GG+GC genotype. Analysis of the promoter region of the interleukin-6 rs1800795 gene polymorphism showed no statistically significant difference in allele frequency either between inflammatory bowel disease patients and healthy controls or between the two inflammatory bowel disease phenotypes and healthy controls. Associations presented in this study give a potentially important insight into the role of interleukin-6 and C-reactive protein signaling and interleukin-6 polymorphism in the pathogenesis of Crohn’s disease and ulcerative colitis disease.

A diet based on cured acorn-fed ham with oleic acid content promotes anti-inflammatory gut microbiota and prevents ulcerative colitis in an animal model

Background

Diets based on meat products are not recommended in the case of ulcerative colitis (UC). The objective here is to test if some traditional cured meat products, as acorn-fed ham (high levels of oleic acid), may be useful for controlling inflammatory diseases as UC in animal models, which could represent a new dietary complementary intervention in the prevention of this inflammatory disease in humans.

Methods

Two rat cohorts have been used: conventional vegetable rat feed and acorn-fed ham. UC was induced with DSS in drinking water ad libitum for 1 week. Short-chain fatty acids (SCFAs) and 16S rRNA metagenomics from bacterial populations were analyzed in cecum samples. Colon samples were analyzed for histological parameters.

Results

Acorn-fed ham diet induced changes in gut microbiota composition, with pronounced enrichments in anti-inflammatory bacterial genera (Alistipes, Blautia, Dorea, Parabacteroides). The animals with this diet showed a strong reduction in most parameters associated to ulcerative colitis: disease activity index, macroscopic score of colitis, epitelium alteration in colon mucosa, inflammatory cell density in colon, myeloperoxidase titers in colon, proinflammatory cytokines (IL-17, IFN-γ). Also, acorn-fed ham diet animals showed increased total antioxidant activity an oleic acid levels in plasma, as well as higher short-chain fatty acid concentrations in cecum (isobutyric, isovaleric and valeric).

Conclusions

In the acorn-fed ham cohort, as a result of the dietary intake of oleic acid and low intake of omega-6 fatty acids, a strong preventive effect against UC symptoms was observed.

Evaluating tofacitinib citrate in the treatment of moderate-to-severe active ulcerative colitis: design, development and positioning of therapy

The etiology of ulcerative colitis (UC) is complex and involves a host of genetic, epigenetic and environmental factors. Over the last thirty years, signaling pathways like the Janus kinase (JAK) signaling pathway have been implicated in its pathogenesis. Pharmacologic blockade of this pathway is available through several small molecule inhibitors, including tofacitinib. Tofacitinib is an orally administered pan-JAK inhibitor that was first approved by the Food and Drug Administration (FDA) for use in rheumatologic disorders such as rheumatoid arthritis and psoriatic arthritis. The FDA approved its use in moderate-to-severe active ulcerative colitis in 2018. The aim of this review will be to discuss the role of tofacitinib in ulcerative colitis. We will discuss the role of JAK-STAT signaling, clinical data available for tofacitinib, and the safety profile for this therapy. Tofacitinib's place in the UC management algorithm is currently being debated. This effective oral therapy is poised to be a mainstay of UC therapeutics. This review will highlight the key clinical features and detail the UC experience to date.

Cellular and Molecular Therapeutic Targets in Inflammatory Bowel Disease-Focusing on Intestinal Barrier Function

The human gut relies on several cellular and molecular mechanisms to allow for an intact and dynamical intestinal barrier. Normally, only small amounts of luminal content pass the mucosa, however, if the control is broken it can lead to enhanced passage, which might damage the mucosa, leading to pathological conditions, such as inflammatory bowel disease (IBD). It is well established that genetic, environmental, and immunological factors all contribute in the pathogenesis of IBD, and a disturbed intestinal barrier function has become a hallmark of the disease. Genetical studies support the involvement of intestinal barrier as several susceptibility genes for IBD encode proteins with key functions in gut barrier and homeostasis. IBD patients are associated with loss in bacterial diversity and shifts in the microbiota, with a possible link to local inflammation. Furthermore, alterations of immune cells and several neuro-immune signaling pathways in the lamina propria have been demonstrated. An inappropriate immune activation might lead to mucosal inflammation, with elevated secretion of pro-inflammatory cytokines that can affect the epithelium and promote a leakier barrier. This review will focus on the main cells and molecular mechanisms in IBD and how these can be targeted in order to improve intestinal barrier function and reduce inflammation.

Inflammatory bowel disease therapy: blockade of cytokines and cytokine signaling pathways

PURPOSE OF REVIEW

Treatment of inflammatory bowel disease (IBD) patients can vary depending on the degree of response, lack of response or intolerance to conventional or biological agents aimed at blocking various cytokines or integrins. Recent therapies targeting several cytokines were reviewed to evaluate efficacy in IBD patients.

RECENT FINDINGS

Ustekinumab is an interleukin inhibitor which blocks the p40 subunit of IL-12 and IL-23 axis and is already approved for the treatment of Crohn's disease patients, specially those who had inadequate response or intolerance to conventional treatment with anti-TNF-α agents. Several treatments have been developed that are focused on the blockade of specific cytokines such as IL-6, IL-12, IL-13, IL-17, IL-23 and a chemokine named IFN-γ-inducible protein-10 as well as some oral small-molecule inhibitors of intracellular cytoplasmic tyrosine kinases like tofacitinib, filgotinib and upadacitinib.

SUMMARY

Several biologics blocking different and specific cytokines and oral small molecule agents have been and are being evaluated in IBD patients. A comprehensive understanding of the underlying immunological mechanisms will allow to develop effective and safe agents that inhibit one or more cytokines to improve the outcome in patients with IBD.

Evaluation of interleukin-6 and its soluble receptor components sIL-6R and sgp130 as markers of inflammation in inflammatory bowel diseases

PURPOSE

Interleukin-6 (IL-6) production and signalling are increased in the inflamed mucosa in inflammatory bowel diseases (IBD). As published serum levels of IL-6 and its soluble receptors sIL-6R and sgp130 in IBD are from small cohorts and partly contradictory, we systematically evaluated IL-6, sIL-6R and sgp130 levels as markers of disease activity in Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Consecutive adult outpatients with confirmed CD or UC were included, and their disease activity and medication were monitored. Serum from 212 CD patients (815 measurements) and 166 UC patients (514 measurements) was analysed, and 100 age-matched healthy blood donors were used as controls.

RESULTS

IL-6 serum levels were significantly elevated in active versus inactive CD and UC, also compared with healthy controls. However, only a fraction of IBD patients showed increased serum IL-6. IL-6 levels ranged up to 32.7 ng/mL in active CD (> 5000-fold higher than in controls), but also up to 6.9 ng/mL in inactive CD. Increases in active UC (up to 195 pg/mL) and inactive UC (up to 27 pg/mL) were less pronounced. Associations between IL-6 serum levels and C-reactive protein concentrations as well as leukocyte and thrombocyte counts were observed. Median sIL-6R and sgp130 levels were only increased by up to 15%, which was considered of no diagnostic significance.

CONCLUSIONS

Only a minority of IBD patients shows elevated IL-6 serum levels. However, in these patients, IL-6 is strongly associated with disease activity. Its soluble receptors sIL-6R and sgp130 do not appear useful as biomarkers in IBD.

Calcimimetic R568 inhibits tetrodotoxin-sensitive colonic electrolyte secretion and reduces c-fos expression in myenteric neurons

AIMS

Calcium-sensing receptor (CaSR) is expressed on neurons of both submucosal and myenteric plexuses of the enteric nervous system (ENS) and the CaSR agonist R568 inhibited Cl^- secretion in intestine. The purpose of this study was to localize the primary site of action of R568 in the ENS and to explore how CaSR regulates secretion through the ENS.

MATERIALS AND METHODS

Two preparations of rat proximal and distal colon were used. The full-thickness preparation contained both the submucosal and myenteric plexuses, whereas for the "stripped" preparation the myenteric plexus with the muscle layers was removed. Both preparations were mounted onto Ussing chambers and Cl^- secretory responses were compared by measuring changes in short circuit current (I_sc). Two tissue-specific CaSR knockouts (i.e., neuron-specific vs. enterocyte-specific) were generated to compare the effect of R568 on expression of c-fos protein in myenteric neurons by immunocytochemistry.

KEY FINDINGS

In full-thickness colons, tetrodotoxin (TTX) inhibited I_sc, both in proximal and distal colons. A nearly identical inhibition was produced by R568. However, in stripped preparations, while the effect of TTX on I_sc largely remained, the effect of R568 was nearly completely eliminated. In keeping with this, R568 reduced c-fos protein expression only in myenteric neurons of wild type mice and mutant mice that contained CaSR in neurons (i.e., ^villinCre/Casr^flox/flox mice), but not in myenteric neurons of ^nestinCre/Casr^flox/flox mice in which neuronal cell CaSR was eliminated.

SIGNIFICANCE

These results indicate that R568 exerts its anti-secretory effects predominantly via CaSR-mediated inhibition of neuronal activity in the myenteric plexus.

The Innate and Adaptive Immune System as Targets for Biologic Therapies in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory condition causing inflammation of gastrointestinal and systemic cells, with an increasing prevalence worldwide. Many factors are known to trigger and maintain inflammation in IBD including the innate and adaptive immune systems, genetics, the gastrointestinal microbiome and several environmental factors. Our knowledge of the involvement of the immune system in the pathophysiology of IBD has advanced rapidly over the last two decades, leading to the development of several immune-targeted treatments with a biological source, known as biologic agents. The initial focus of these agents was directed against the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) leading to dramatic changes in the disease course for a proportion of patients with IBD. However, more recently, it has been shown that a significant proportion of patients do not respond to anti-TNF-α directed therapies, leading a shift to other inflammatory pathways and targets, including those of both the innate and adaptive immune systems, and targets linking both systems including anti-leukocyte trafficking agents-integrins and adhesion molecules. This review briefly describes the molecular basis of immune based gastrointestinal inflammation in IBD, and then describes how several current and future biologic agents work to manipulate these pathways, and their clinical success to date.

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.

The Innate Immune Receptor NLRX1 Functions as a Tumor Suppressor by Reducing Colon Tumorigenesis and Key Tumor-Promoting Signals

NOD-like receptor (NLR) proteins are intracellular innate immune sensors/receptors that regulate immunity. This work shows that NLRX1 serves as a tumor suppressor in colitis-associated cancer (CAC) and sporadic colon cancer by keeping key tumor promoting pathways in check. Nlrx1^−/− mice were highly susceptible to CAC, showing increases in key cancer-promoting pathways including nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK), signal transducer and activator of transcription 3 (STAT3), and interleukin 6 (IL-6). The tumor-suppressive function of NLRX1 originated primarily from the non-hematopoietic compartment. This prompted an analysis of NLRX1 function in the Apc^min/+ genetic model of sporadic gastrointestinal cancer. NLRX1 attenuated Apc^min/+ colon tumorigenesis, cellular proliferation, NF-κB, MAPK, STAT3 activation, and IL-6 levels. Application of anti-interleukin 6 receptor (IL6R) antibody therapy reduced tumor burden, increased survival, and reduced STAT3 activation in Nlrx1^−/−Apc^min/+ mice. As an important clinical correlate, human colon cancer samples expressed lower levels of NLRX1 than healthy controls in multiple patient cohorts. These data implicate anti-IL6R as a potential personalized therapy for colon cancers with reduced NLRX1.

Effect of a Medicinal Agaricus blazei Murill-Based Mushroom Extract, AndoSan™, on Symptoms, Fatigue and Quality of Life in Patients with Ulcerative Colitis in a Randomized Single-Blinded Placebo Controlled Study

Background

Ingestion of AndoSan^™, based on the mushroom Agaricus blazei Murill, has previously been shown to exhibit anti-inflammatory effects because of reduction of pro-inflammatory cytokines in healthy individuals and patients with ulcerative colitis. In this randomized single-blinded placebo controlled study we examined whether intake of AndoSan^™ also resulted in clinical effects.

Methods and Findings

50 patients with symptomatic ulcerative colitis were block-randomized and blinded for oral daily intake of AndoSan^™ or placebo for the 21 days’ experimental period. The patients reported scores for symptoms, fatigue and health related quality of life (HRQoL) at days 0, 14 and 21. Fecal calprotectin and general blood parameters were also analyzed. In the AndoSan^™ group (n = 24) symptoms improved from baseline (day 0) to days 14 and 21, with respective mean scores (95% CI) of 5.88 (4.92–6.83), 4.71 (3.90–5.52) (p = 0.002) and 4.50 (3.70–5.30) (p = 0.001). Corresponding improved mean scores (±SD) for total fatigue were 16.6 (5.59), 14.1 (4.50) (p = 0.001) and 15.1 (4.09) (p = 0.023). These scores in the placebo group (n = 26) were not improved. When comparing the two study groups using mixed model statistics, we found significant better scores for the AndoSan^™-patients. HRQoL for dimensions bodily pain, vitality, social functioning and mental health improved in the AndoSan^™ group. There were no alterations in general blood samples and fecal calprotectin.

Conclusions

Beneficiary effects on symptoms, fatigue and HRQoL from AndoSan^™ consumption were demonstrated in this per-protocol study, supporting its use as a supplement to conventional medication for patients with mild to moderate symptoms from ulcerative colitis. The patients did not report any harms or unintended effects of AndoSan^™ in this study.

Trial Registration

ClinicalTrials.gov NCT01496053

Interleukin 6 Increases Production of Cytokines by Colonic Innate Lymphoid Cells in Mice and Patients With Chronic Intestinal Inflammation

BACKGROUND & AIMS

Innate lymphoid cells (ILCs) are a heterogeneous group of mucosal inflammatory cells that participate in chronic intestinal inflammation. We investigated the role of interleukin 6 (IL6) in inducing activation of ILCs in mice and in human beings with chronic intestinal inflammation.

METHODS

ILCs were isolated from colons of Tbx21(-/-) × Rag2(-/-) mice (TRUC), which develop colitis; patients with inflammatory bowel disease (IBD); and patients without colon inflammation (controls). ILCs were characterized by flow cytometry; cytokine production was measured by enzyme-linked immunosorbent assay and cytokine bead arrays. Mice were given intraperitoneal injections of depleting (CD4, CD90), neutralizing (IL6), or control antibodies. Isolated colon tissues were analyzed by histology, explant organ culture, and cell culture. Bacterial DNA was extracted from mouse fecal samples to assess the intestinal microbiota.

RESULTS

IL17A- and IL22-producing, natural cytotoxicity receptor-negative, ILC3 were the major subset of ILCs detected in colons of TRUC mice. Combinations of IL23 and IL1α induced production of cytokines by these cells, which increased further after administration of IL6. Antibodies against IL6 reduced colitis in TRUC mice without significantly affecting the structure of their intestinal microbiota. Addition of IL6 increased production of IL17A, IL22, and interferon-γ by human intestinal CD3-negative, IL7-receptor-positive cells, in a dose-dependent manner.

CONCLUSIONS

IL6 contributes to activation of colonic natural cytotoxicity receptor-negative, CD4-negative, ILC3s in mice with chronic intestinal inflammation (TRUC mice) by increasing IL23- and IL1α-induced production of IL17A and IL22. This pathway might be targeted to treat patients with IBD because IL6, which is highly produced in colonic tissue by some IBD patients, also increased the production of IL17A, IL22, and interferon-γ by cultured human colon CD3-negative, IL7-receptor-positive cells.

Characterization of Serum Cytokine Profile in Predominantly Colonic Inflammatory Bowel Disease to Delineate Ulcerative and Crohn's Colitides

BACKGROUND

As accessible diagnostic approaches fail to differentiate between ulcerative colitis (UC) and Crohn’s colitis (CC) in one-third of patients with predominantly colonic inflammatory bowel disease (IBD), leading to inappropriate therapy, we aim to investigate the serum cytokine levels in these patients in search of molecular biometric markers delineating UC from CC.

METHODS

We measured 38 cytokines, chemokines, and growth factors using magnetic-bead-based multiplex immunoassay in 25 UC patients, 28 CC patients, and 30 controls. Our results are compared with those from a review of current literature regarding advances in serum cytokine profiles and associated challenges preventing their use for diagnostic/prognostic purposes.

RESULTS

Univariate analysis showed statistically significant increases of eotaxin, GRO, and TNF-α in UC patients compared to controls (Ctrl); interferon γ, interleukin (IL)-6, and IL-7 in CC group compared to Ctrl; and IL-8 in both UC and CC versus Ctrl. No cytokines were found to be different between UC and CC. A generalized linear model identified combinations of cytokines, allowing the identification of UC and CC patients, with area under the curve (AUC) = 0.936, as determined with receiver operating characteristic (ROC) analysis.

CONCLUSIONS

The current knowledge available about circulating cytokines in IBD is often contradictory. The development of an evidence-based tool using cytokines for diagnostic accuracy is still preliminary.

Selected biologic markers of inflammation and activity of Crohn's disease

The study aimed to compare the accuracy of selected biologic markers in assessing the disease activity in patients with Crohn's disease (CD). The analysis included serum IL-2, IL-6, IL-17, TNF-α, IFN-γ, hsCRP, peripheral CD4 + CD25 + FOXP3 + regulatory T cells, as well as fecal calprotectin and lactoferrin. A group of 55 adults with CD was enrolled to the study. Disease activity was assessed using Crohn's Disease Endoscopic Index of Severity (CDEIS), which currently represents the gold standard for the evaluation of endoscopic activity. For clinical activity scoring, the Crohn's Disease Activity Index (CDAI) was used. Concentrations of investigated markers were estimated by means of flow cytometry and enzyme-linked immunosorbent assays, and the results were correlated with both indices. The study demonstrated that both fecal markers, i.e. calprotectin (r = 0.827, p < 0.001) and lactoferrin (r = 0.704, p < 0.001), correlate closely with CDEIS score, and might be used to evaluate the severity of CD in clinical setting. The correlation of those markers with CDAI was also significant, with r = 0.742 for calprotectin (p < 0.001) and r = 0.675 for lactoferrin (p < 0.05). As for the other investigated markers, only hsCRP (r = 0.672, p < 0.001) and IL-17 (r = 0.296, p < 0.005) correlated closely with CDEIS. The correlation of the markers with CDAI was also significant, though weaker, with r = 0.518 for hsCRP (p < 0.001) and r = 0.296 for IL-17 (p < 0.05). The study showed that IL-17, despite its vague role in the pathogenesis of CD, might be a useful marker, comparable with hsCRP, in assessing the activity of the disease.

From physiology to disease and targeted therapy: interleukin-6 in inflammation and inflammation-associated carcinogenesis

Since its discovery in 1986, originally as B cell stimulating factor 2, the knowledge on IL-6 for immune homeostasis and its pathophysiological implications has rapidly increased. It is now clear that IL-6, alone or in combination with other cytokines, is an architect for shaping and generating immune responses which exerts profound activities on the induction of acute-phase reactions, the differentiation of B lymphocytes, the modulation of T cell apoptosis, the activation of T helper cells and the balance between regulatory T cells and Th17 cells. In parallel to the identification of these physiologic functions, IL-6 has emerged as a critical mediator for perpetuating chronic inflammation and autoimmunity and is increasingly recognized as a key cytokine for linking chronic inflammation to cancer development. In this review, we begin by briefly summarizing the molecular events of IL-6 regulation and signaling and then describe the role of IL-6 in orchestrating innate and adaptive immune responses and its immunopathological relevance for chronic inflammatory diseases. We further outline how IL-6 links chronic inflammation and cancer development and finally provide an outlook on novel therapeutic strategies targeting IL-6 signaling for the treatment of chronic inflammatory diseases and cancer.