The B-cell system in inflammatory bowel disease

Oral reovirus reshapes the gut microbiome and enhances antitumor immunity in colon cancer

The route of oncolytic virotherapy is pivotal for immunotherapeutic efficacy in advanced cancers. In this preclinical study, an oncolytic reovirus (RC402) is orally administered to induce antitumor immunity. Oral reovirus treatment shows no gross toxicities and effectively suppresses multifocal tumor lesions. Orally administered reovirus interacts with the host immune system in the Peyer's patch of the terminal ileum, increases IgA+ antibody-secreting cells in the lamina propria through MAdCAM-1+ blood vessels, and reshapes the gut microbiome. Oral reovirus promotes antigen presentation, type I/II interferons, and T cell activation within distant tumors, but does not reach or directly infect tumor cells beyond the gastrointestinal tract. In contrast to intratumoral reovirus injection, the presence of the gut microbiome, Batf3+ dendritic cells, type I interferons, and CD8+ T cells are indispensable for orally administered reovirus-induced antitumor immunity. Oral reovirus treatment is most effective when combined with αPD-1(L1) and/or αCTLA-4, leading to complete colon tumor regression and protective immune memory. Collectively, oral reovirus virotherapy is a feasible and effective immunotherapeutic strategy in preclinical studies.

New Insights and Future Perspectives of APRIL in IgA Nephropathy

IgA nephropathy (IgAN) is characterized by immune-mediated glomerulonephritis, with the accumulation of galactose-deficient IgA1 (Gd-IgA1) in the glomeruli and increased levels of circulating Gd-IgA1 and Gd-IgA1-containing immune complexes. An incomplete understanding of the underlying mechanisms and differences in clinical and pathological features between individuals and ethnicities has contributed to the lack of established treatments for IgAN. A tumor necrosis factor (TNF) family member, a proliferation-inducing ligand (APRIL), is a crucial cytokine essential for the generation and survival of plasma cells. Recent studies demonstrated that APRIL is a pivotal mediator in the production of Gd-IgA1 in IgAN. As our understanding of the autoimmune pathogenesis underlying IgAN has improved, various pharmacological therapeutic targets, including APRIL antagonists, have emerged. Preliminary results showed that APRIL-targeting agents effectively reduced proteinuria and Gd-IgA1 levels without significantly increasing adverse events, indicating their potential as novel therapeutic agents for IgAN. In the present review, we discuss the current understanding of the role of APRIL in the pathogenesis of IgAN and novel therapeutic strategies focusing on APRIL-targeting agents for IgAN. APRIL inhibitors may offer new hope to patients with IgAN.

Integrated analyses reveal the diagnostic and predictive values of COL5A2 and association with immune environment in Crohn's disease

The pathogenesis of Crohn's disease (CD) involves abnormal immune cell infiltration and dysregulated immune response. Therefore, thorough research on immune cell abnormalities in CD is crucial for improved treatment of this disease. Single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data of CD were obtained from the Gene Expression Omnibus (GEO) database. Cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT), weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) networks evaluated the proportion of immune infiltrating cells, constructed co-expression network and identified key genes, respectively. Based on the dataset (GSE134809), 15 cell clusters were defined and labeled as different cell types. Among the 11 modules, the yellow module had the closest relationship with plasma cells (cluster 5). Confirmed using RNA sequencing and IHC assay, the expression of COL5A2 in CD samples was higher than that in control samples. Furthermore, the COL5A2 protein expression remarkably decreased in the group of patients who responded to anti-tumor necrosis factor (TNF) treatments, compared to the non-response group. The comprehensive analyses described here provided novel insight into the landscape of CD-associated immune environment. In addition, COL5A2 were identified as potential diagnostic indicators for CD, as well as promising predictive markers for CD patients.

Exploring shared molecular signatures and regulatory mechanisms in nonalcoholic steatohepatitis and inflammatory bowel disease using integrative bioinformatics analysis

The co-existence of inflammatory bowel disease (IBD) and non-alcoholic steatohepatitis (NASH) has raised interest in identifying shared molecular mechanisms and potential therapeutic targets. However, the relationship between these two diseases remains unclear and effective medical treatments are still lacking. Through the bioinformatics analysis in this study, 116 shared differentially expressed genes (SDEGs) were identified between IBD and NASH datasets. GO and KEGG pathway analyses revealed significant involvement of SDEGs in apoptotic processes, cell death, defense response, cytokine and chemokine activity, and signaling pathways. Furthermore, weighted gene co-expression network analysis (WGCNA) identified five shared signature genes associated specifically with IBD and NASH, they were CXCL9, GIMAP2, ADAMTS5, GRAP, and PRF1. These five genes represented potential diagnostic biomarkers for distinguishing patients with diseases from healthy individuals by using two classifier algorithms and were positively related to autophagy, ferroptosis, angiogenesis, and immune checkpoint factors in the two diseases. Additionally, single-cell analysis of IBD and NASH samples highlighted the expression of regulatory genes in various immune cell subtypes, emphasizing their significance in disease pathogenesis. Our work elucidated the shared signature genes and regulatory mechanisms of IBD and NASH, which could provide new potential therapies for patients with IBD and NASH.

Sirtuin2 suppresses the polarization of regulatory T cells toward T helper 17 cells through repressing the expression of signal transducer and activator of transcription 3 in a mouse colitis model

INTRODUCTION

Regulatory T cells (Tregs) play an important role in inflammatory bowel diseases (IBDs) through modulating intestinal inflammation. However, the factors affecting Treg function and plasticity during IBD progression are not thoroughly disclosed. The current study aims to reveal new molecular mechanisms affecting Treg plasticity.

METHODS

A mouse strain, in which tdTomato and enhanced green fluorescent protein were under the control of the Foxp3 promoter and Il17a promoter, was established and subjected to colitis induction with dextran sulfate sodium. The existence of Tregs and IL-17-expressing Tregs (i.e., Treg/T helper 17 [Th17] cells) were observed and sorted from the spleen, mesenteric lymph nodes, and lamina propria by flow cytometry, followed by measuring Sirtuin2 (Sirt2) expression using quantitative reverse transcription polymerase chain reaction and Immunoblotting. Lentivirus-induced Sirt2 silencing was applied to determine the impact of Sirt2 on Treg polarization to Treg/Th17 cells and even Th17 cells. The effect of Sirt2 on Stat3 was analyzed by flow cytometry and immunoblotting.

RESULTS

Sirt2 was highly expressed in lamina propria Tregs and it moderately suppressed Foxp3 expression as well as the immunosuppressive function of Tregs. Surprisingly, lentivirus-mediated Sirt2 silencing promoted the generation of Treg/Th17 cells out of Tregs. Sirt2 silencing also enhanced the generation of Th17 cells out of Tregs under the Th17 induction condition. Furthermore, Sirt2 inhibited Th17 induction by suppressing the protein level of the signal transducer and activator of transcription 3.

CONCLUSION

Sirt2 suppresses Treg function but also inhibits Treg polarization toward Treg/Th17 cells and Th17 cells. The ultimate effect of Sirt2 on colitis might depend on the balance among Tregs, Treg/Th17 cells, and Th17 cells.

Kidney Diseases Associated With Inflammatory Bowel Disease: Impact of Chronic Histologic Damage, Treatments, and Outcomes

INTRODUCTION

Kidney disease is a well-known extraintestinal manifestation (EIM) associated with inflammatory bowel disease (IBD), with a variety of underlying etiologies. However, little is known about the overall outcomes and predictors.

METHODS

This is a retrospective, observational cohort study. Patients with IBD in whom a native kidney biopsy was performed at Mayo Clinic (Rochester, MN) between 1994 and 2022, were included. Demographic, clinical, and histologic characteristics of prognostic interest were collected. The main outcomes were kidney failure, disease remission, kidney function changes at last follow-up, and death.

RESULTS

From a total cohort of 318 patients, we selected a study group of 111 patients followed-up with at our institution (45 ulcerative colitis [UC] and 66 Crohn's disease [CD]), with a mean age of 48 ± 17 years (40% females). IgA nephropathy (IgAN), chronic interstitial nephritis (CIN), and acute interstitial nephritis (AIN) were the most common diagnoses (22%, 19%, 13%, respectively). Median estimated glomerular filtration rate (eGFR) at presentation was 30 ml/min per 1.73 m2 (interquartile range [IQR]: 17-54) and urinary protein-to-creatinine ratio [UPCR] 0.8 g/g (0.3-3.4), without differences between IBD types. During a median follow-up of 59 months (12-109), 29 patients (26%) reached kidney failure. By multivariable analysis, the main predictors of kidney failure were age (hazard ratio [HR]: 1.04; P = 0.002), baseline eGFR (HR: 0.94; P = 0.003) and histologic chronicity score (HR: 4.01; P < 0.001). Therapeutic management varied according to underlying etiology. Global survival (kidney failure + death) was significantly better in patients who achieved complete or partial remission, or stabilization or improvement of kidney function.

CONCLUSION

One-fourth of patients with IBD with kidney disease may reach kidney failure, and the main determinants of this outcome is age, baseline eGFR, and degree of chronicity in kidney biopsy.

Exclusive Enteral Nutrition Orchestrates Immunological Balances as Early as Week 4 in Adult Patients of Crohn's Disease: A Pilot, Open-Lable Study

BACKGROUND AND AIMS

The efficacy and underlying mechanisms of exclusive enteral nutrition (EEN) in adult patients with Crohn's disease (CD) remain controversial. This study aimed to evaluate the role of EEN in adult patients with CD and to explore the mechanisms from the perspective of immunoregulation.

METHODS

This is a prospective, open-label pilot study. Active patients with CD were enrolled and prescribed an amino-acid-rich elemental diet for 12 weeks. Dynamic changes in immune cells, including neutrophils, monocytes, T cells and B cells, were detected by flow cytometry. Plasma cytokines were evaluated by ELISA.

RESULTS

Twenty adult patients with CD were enrolled. Among them, 1 discontinued treatment due to poor compliance, and 19 patients were included for final analysis. Clinical remission was achieved in 47.37% (9/19), 63.16% (12/19), and 73.68% (14/19) patients at weeks 4, 8, and 12, respectively. Endoscopic remission and transmural healing were achieved in 52.63% (10/19) and 15.79% (3/19) patients at week 12. Notably, there was no significant difference in clinical remission between week 4 and week 8 (p = 0.33) or week 12 (p = 0.09). Furthermore, we observed a rapid reconstitution of immunologic homeostasis as early as week 4. At week 4, both the frequency and activation of neutrophils and monocytes were decreased after EEN therapy. Significant decreases in Th17 cells and naïve B cells, increases in memory B cells, and regulatory B cells were also detected. These changes remained stable at weeks 8 and 12.

CONCLUSIONS

EEN with an amino-acid-rich elemental diet orchestrated immunological balances and induces clinical remission in adult CD patients as early as week 4, suggesting a 4-week EEN therapy may be feasible and practicable in clinical practice.

Ocrelizumab-induced colitis and cytomegalovirus infection and their disadvantageous interaction with underlying multiple sclerosis

Ocrelizumab is a humanized monoclonal antibody against the B-lymphocyte antigen CD20 and the only approved treatment option in primary progressive multiple sclerosis. Herpesvirus-related infections like cytomegalovirus (CMV) infections are common in patients receiving ocrelizumab, whereas gastrointestinal side effects with inflammatory bowel disease (IBD) like esophagitis or colitis are very rare. This case report describes the challenging clinical, endoscopic, and histologic features of an ocrelizumab-induced colitis overlapping with CMV infection and their disadvantageous interaction with the underlying multiple sclerosis.

IgA nephropathy associated with Crohn's disease

The relationship between IgA nephropathy (IgAN) and Crohn’s disease was reported. IgAN is the most common primary glomerulonephritis and one of the leading causes of chronic kidney disease and end-stage renal failure, and up to 50% of cases progressed to end-stage renal disease within 25 years after IgAN diagnosis. However, specific and effective therapeutic strategies are still lacking. In this review, we discuss the possibility of the mechanism involved in IgAN associated with Crohn’s disease based on the findings of basic and clinical studies. Although the etiology of IgAN associated with Crohn’s disease is not permanent and various factors are thought to be involved, the stabilization of the disease condition of Crohn’s disease is believed to help treat IgAN.

Anti-CD20 monoclonal antibody (mAb) therapy and colitis: A case series and review

The US Food and Drug Administration (FDA) recently issued a warning regarding ocrelizumab due to reports of colitis among patients taking this medication. Since it is the only FDA-approved therapy for primary progressive multiple sclerosis (PPMS), further research on this adverse event is necessary, and healthcare professionals should be informed of potential treatment options. In this review, we summarize the available data on the incidence of inflammatory colitis associated with anti-CD20 monoclonal antibodies (mAbs), such as ocrelizumab and rituximab, used in MS treatment. Although the exact pathophysiology of anti-CD20-induced colitis remains unknown, immunological dysregulation through treatment-mediated B-cell depletion has been proposed as a possible mechanism. Our study highlights the importance of clinicians being aware of this potential side effect, and patients taking these medications should be closely monitored for any new-onset gastrointestinal symptoms or diarrheal illness. Research indicates that prompt intervention with endoscopic examination and medical or surgical therapies can ensure timely and effective management, thus improving patient outcomes. However, large-scale studies are still needed to determine the associated risk factors and to establish definitive guidelines for the clinical evaluation of MS patients on anti-CD20 medications.

Human intestinal B cells in inflammatory diseases

The intestinal lumen contains an abundance of bacteria, viruses and fungi alongside ingested material that shape the chronically active intestinal immune system from early life to maintain the integrity of the gut epithelial barrier. In health, the response is intricately balanced to provide active protection against pathogen invasion whilst tolerating food and avoiding inflammation. B cells are central to achieving this protection. Their activation and maturation generates the body's largest plasma cell population that secretes IgA, and the niches they provide support systemic immune cell specialization. For example, the gut supports the development and maturation of a splenic B cell subset - the marginal zone B cells. In addition, cells such as the T follicular helper cells, which are enriched in many autoinflammatory diseases, are intrinsically associated with the germinal centre microenvironment that is more abundant in the gut than in any other tissue in health. In this Review, we discuss intestinal B cells and their role when a loss of homeostasis results in intestinal and systemic inflammatory diseases.

Patched 1 and C-C Motif Chemokine Receptor 6 Distinguish Heterogeneous T Helper 17 Subsets in Colitic Lamina Propria

T helper 17 (Th17) cells contribute to the pathogenesis of inflammatory bowel diseases (IBD). However, their heterogeneity and regulatory mechanisms in IBD are not completely disclosed. A mouse colitis model was established. Th17 cells were enriched from the mesenteric lymph nodes (mLN) and lamina propria (LP). The phenotypes and functions of Th17 subsets were analyzed by flow cytometry, Immunoblotting, and real-time RT-PCR. The contributions of the Th17 subsets to colitis pathogenesis were evaluated by histology, ELISA, and flow cytometry after adoptive transfer. Smoothened (SMO), GLI family zinc finger 1 (Gli1), and GLI family zinc finger 3 (Gli3) were markedly up-regulated while Patched 1 (PTCH1) was down-regulated in LP Th17 cells in colitic lamina propria. Based on the expression of PTCH1 and C-C motif chemokine receptor 6 (CCR6), LP Th17 cells were divided into a PTCH1^lowCCR6^low Th17 subset and a PTCH1^highCCR6^high Th17 subset. The former expressed higher T-bet, IFN-γ, TNF-α, IL-1β, and GM-CSF but lower IL-17A, IL-22, IL-17F, and Gli3 than the latter. The PTCH1^highCCR6^high Th17 subset was more resistant to polarization towards T helper 1 (Th1) than the PTCH1^lowCCR6^low Th17 subset. Moreover, the PTCH1^highCCR6^high Th17 subset was more competent to maintain Th17 identity. The PTCH1^highCCR6^high Th17 subset induced less severe colitis than the PTCH1^lowCCR6^low Th17 subset. PTCH1^highCCR6^high Th17 cells are Th17 cells whereas PTCH1^lowCCR6^low Th17 cells are Th1-like Th17 cells. Our study deepens the understanding of Th17 heterogeneity and plasticity in colitis.

Causal association between inflammatory bowel disease and IgA nephropathy: A bidirectional two-sample Mendelian randomization study

Background: An association between inflammatory bowel disease (IBD) [which includes ulcerative colitis (UC) and Crohn's disease (CD)] and IgA nephropathy (IgAN) has been discovered in observational studies, but the causal relationship is still unknown. The aim of this study was to clarify the causal link between IBD (which includes UC and CD) and IgAN via a two-sample Mendelian randomization (MR) analysis. Methods: Eligible single-nucleotide polymorphisms (SNPs) were selected as instrumental variables (IVs) for analyses and were obtained from the publicly available genome-wide association study (GWAS) summary statistics. Inverse-variance weighting (IVW), Mendelian randomization-Egger (MR-Egger) regression, the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test, and the weighted median were utilized to obtain the results. The MR-PRESSO test and MR-Egger regression were also performed to detect and correct horizontal pleiotropy. The Cochran's Q test and "leave-one-out" analysis were also conducted to assess the stability and reliability of the MR results. Results: This study found that IBD, UC, and CD all had significant positive causal effects on IgAN risk (IBD: OR = 1.58, 95% CI 1.15-2.16, p = 4.53 × 10-3; UC: OR = 1.55, 95% CI 1.14-2.11, p = 4.88 × 10-3; CD: OR = 1.57, 95% CI 1.21-2.03, p = 5.97 × 10-4). No significant horizontal pleiotropic effect was found for the causal association between IBD, UC, CD, and the risk of IgAN. Cochran's Q test identified no evidence of heterogeneity for the IV estimates. The "leave-one-out" sensitivity analysis also revealed that the MR results were robust. Conclusion: The results of this two-sample MR analysis supported that IBD, UC, and CD were causally associated with the risk of IgAN, while there was no sufficient evidence for the causal effect of IgAN on IBD, UC, or CD. Our findings provide theoretical support and a new perspective for the diagnosis and treatment of these two diseases.

Acute psychological stress increases paracellular permeability and modulates immune activity in rectal mucosa of healthy volunteers

BACKGROUND

Psychological stress and increased permeability are implicated as contributing factors in the initiation and worsening of gastrointestinal diseases. A link between stress and intestinal permeability has been shown in animal models as well as in human small intestine, but stress effects on the human colorectal mucosal barrier has not been reported.

OBJECTIVE

To investigate the potential effects of acute psychological stress on colorectal mucosal barrier function and to explore stress-induced molecular events in the rectal mucosa under healthy conditions.

METHODS

Endoscopic biopsies were taken from the rectosigmoid region of healthy volunteers, who had been subjected to dichotomous listening stress and after a control session, respectively. Paracellular and transcellular permeability were assessed in modified Ussing chambers. RNA expression (microarray technology confirmed by quantitative real-time polymerase chain reaction) and biological pathway analysis were used to investigate the local mucosal response to acute stress.

RESULTS

Dichotomous listening stress induced a subjective and objective stress response, and significantly increased paracellular but not transcellular permeability. We also identified a stress-induced reduction in RNA expression of genes related to immune cell activation and maturation (CR2, CD20, TCLA1, BANK1, CD22, FDCSP), signaling molecules of homing of immune cells to the gut (chemokines: CCL21, CXCL13, and CCL19, and receptors: CCR7, CXCR5), and innate immunity (DUOX2). Eight of the 10 top down-regulated genes are directly involved in B cell activation, signaling and migration. The systemic stress response correlated positively with paracellular permeability and negatively with DUOX2 expression.

CONCLUSION

Dichotomous listening stress increases paracellular permeability and modulates immune cell activity in the rectal mucosa. Further studies are warranted to identify the primary mechanisms of stress-mediated reduction of mucosal defensive activity and barrier dysfunction, and their potential implications for gastrointestinal disorders.

Cepharanthine ameliorates dextran sulphate sodium-induced colitis through modulating gut microbiota

Cepharanthine (CEP) is an active alkaloid isolated from Stephania Cepharantha Hayata. It is reported that the anti-inflammatory properties of CEP could be employed to treat a variety of diseases. In this study, we first found that CEP ameliorates ulcerative colitis (UC) induced by DSS. The effect of CEP on gut microbiota was further evaluated by 16S rRNA gene sequencing, antibiotic pretreatment and faecal microbiota transplantation (FMT). Results showed that the abundances of gut microbiota, such as Romboutsia, Turicibacter and Escherichia-Shigella (especially Romboutsia), were significantly reduced after CEP treatment. Additionally, we explored the mechanisms of CEP by a strategy integrating transcriptomics with network pharmacology. The transcriptome data confirmed that CEP functioned through cytokine and cytokine receptor pathways. The expression levels of 10 pro-inflammatory hub genes (such as CXCL1, CXCL9, CCL7) were positively correlated with the abundance of Romboutsia. Our data identified Romboutsia as a potential pathobiont in UC. Collectively, we confirmed that CEP relieved colon inflammation by modulating gut microbiota and pro-inflammatory cytokine expression. CEP can be adopted to design novel effective therapeutic strategies for UC.

Crohn's disease may promote inflammation in IgA nephropathy: a case-control study of patients undergoing kidney biopsy

Intestinal immunity has been closely associated with the pathogenesis and progression of renal diseases, a relationship known as the "gut-kidney axis." To determine the association between immunoglobulin A nephropathy (IgAN) and Crohn's disease (CD), a clinico-pathological study was performed on patients who had IgAN with CD (CD-IgAN) and without CD (NOS-IgAN). We enrolled 29 patients diagnosed with IgAN via renal biopsy at the Tokyo Yamate Medical Center from 2009 to 2017. The patients were divided into CD-IgAN (n = 18) and NOS-IgAN (n = 11) and evaluated for clinical and pathological findings. IgA subclasses and galactose-deficient IgA1 (Gd-IgA1) were examined via immunohistochemistry using formalin-fixed paraffin-embedded sections from renal biopsy. Our results showed no significant difference in the extent of mesangial IgA subclasses or Gd-IgA1 deposition according to the presence or absence of CD. Pathologically, however, those with CD-IgAN had remarkably higher percentage of global glomerulosclerosis and extent of interstitial fibrosis and tubular atrophy (IF/TA) compared to those with NOS-IgAN. Moreover, the extent of macrophage infiltration in the glomerulus and interstitium was significantly higher in CD-IgAN than in NOS-IgAN. Clinically, the CD-IgAN group had significantly worse responsiveness to steroid treatment compared to the NOS-IgAN group. In conclusion, the similar immunological characteristics of deposited IgA molecules in the glomeruli between the CD-IgAN and NOS-IgAN groups might suggest their etiological similarity. However, a renal pathology showing advanced glomerular and tubulointerstitial sclerosis accompanying increased macrophage infiltration and highly resistant clinical features in patients with CD-IgAN suggests that some pathophysiological factors in CD, including abnormal intestinal immunity, may promote and activate the inflammatory process in IgAN via undetermined mechanisms.

Expression characteristics of polymeric immunoglobulin receptor in Bactrian camel (Camelus bactrianus) lungs

Polymeric immunoglobulin receptor (pIgR), the transmembrane transporter of polymeric immunoglobulin A and M, has multiple immune functions. To explore the characteristics of pIgR expression in Bactrian camel lungs, twelve healthy adult (2-7 years old) Bactrian camels were systematically studied. The results showed that pIgR was mainly expressed in the cytoplasm and membrane of ciliated cells, as well as in the cytoplasm and membrane of basal cells, serous cells of bronchial glands, club cells and alveolar type 2 cells in Bactrian camel lungs. Specially, as the bronchial branches extended, the pIgR expression level in ciliated cells significantly declined (p<0.05), and the corresponding bronchial luminal areas obviously decreased (p<0.05). However, pIgR was not expressed in goblet cells, endocrine cells, alveolar type 1 cells and mucous cells of bronchial glands. The results demonstrated that ciliated cells continuously distributed throughout the whole bronchial tree mucosa were the major expression sites of pIgR, and pIgR was also expressed in basal cells, serous cells of bronchial glands, club cells and alveolar type 2 cells, which would facilitate secretory immunoglobulin A (SIgA) transmembrane transport by pIgR and form an intact protective barrier. Moreover, the pIgR expression level in ciliated cells was positively correlated with the bronchial luminal areas; but negatively correlated with the cleanliness of airflow through the bronchial cross-sections, showing that the pIgR expression level in the bronchial epithelium was inhomogeneous. Our study provided a foundation for further exploring the regulatory functions of immunoglobulins (i.e., SIgA) after transport across the membrane by pIgR in Bactrian camel lungs.

New Insights Into the Epigenetic Regulation of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the colonic mucosa. Environmental factors, genetics, intestinal microbiota, and the immune system are all involved in the pathophysiology of IBD. Lately, accumulating evidence has shown that abnormal epigenetic changes in DNA methylation, histone markers, and non-coding RNA expression greatly contribute to the development of the entire disease. Epigenetics regulates many functions, such as maintaining the homeostasis of the intestinal epithelium and regulating the immune system of the immune cells. In the present study, we systematically summarized the latest advances in epigenetic modification of IBD and how epigenetics reveals new mechanisms of IBD. Our present review provided new insights into the pathophysiology of IBD. Moreover, exploring the patterns of DNA methylation and histone modification through epigenetics can not only be used as biomarkers of IBD but also as a new target for therapeutic intervention in IBD patients.

Anti-HBV drug entecavir ameliorates DSS-induced colitis through PD-L1 induction

PD-L1-mediated signaling is one of the major processes that regulate local inflammatory responses in the gut. To date, protective effects against colitis through direct Fc-fused PD-L1 administration or indirect PD-L1 induction by probiotics have been reported. We have previously shown that the anti-HBV drug entecavir (ETV) induces PD-L1 expression in human hepatocytes. In the present study, we investigated whether ETV induces PD-L1 expression in intestinal cells and provides a protective effect against DSS-induced colitis. ETV induced PD-L1 expression in epithelial cells, rather than T and B cells, improving the symptoms of colitis. In the mechanistic analysis, Th17 cell differentiation was inhibited and B cell infiltration into the lamina propria was reduced. In addition, PD-L1 expression was positively correlated with Foxp3 or CSF1-R. In conclusion, ETV upregulated PD-L1 expression in epithelial cells and ameliorated inflammation in DSS-induced colitis. These results suggest that ETV may be a potential therapeutic agent as a PD-L1 enhancer for the treatment of human IBD.

Antibody secreting cells are critically dependent on integrin α4β7/MAdCAM-1 for intestinal recruitment and control of the microbiota during chronic colitis

T and B cells employ integrin α4β7 to migrate to intestine under homeostatic conditions. Whether those cells differentially rely on α4β7 for homing during inflammatory conditions has not been fully examined. This may have implications for our understanding of the mode of action of anti-integrin therapies in inflammatory bowel disease (IBD). Here, we examined the role of α4β7 integrin during chronic colitis using IL-10^-/- mice, β7-deficient IL-10^-/-, IgA-deficient IL-10^-/- mice, and antibody blockade of MAdCAM-1. We found that α4β7 was predominantly expressed by B cells. β7 deficiency and MAdCAM-1 blockade specifically depleted antibody secreting cells (ASC) (not T cells) from the colonic LP, leading to a fecal pan-immunoglobulin deficit, severe colitis, and alterations of microbiota composition. Colitis was not due to defective regulation, as dendritic cells (DC), regulatory T cells, retinaldehyde dehydrogenase (RALDH) expression, activity, and regulatory T/B-cell cytokines were all comparable between the strains/treatment. Finally, an IgA deficit closely recapitulated the clinical phenotype and altered microbiota composition of β7-deficient IL-10^-/- mice. Thus, a luminal IgA deficit contributes to accelerated colitis in the β7-deficient state. Given the critical/nonredundant dependence of IgA ASC on α4β7:MAdCAM-1 for intestinal homing, B cells may represent unappreciated targets of anti-integrin therapies.

Metabolites and secretory immunoglobulins: messengers and effectors of the host-microbiota intestinal equilibrium

Maintaining commensal diversity is essential to host homeostasis, because microbial species provide a range of metabolic products and continuously educate the host immune system. The mucosal immune system must actively gather information about the composition of the microbiota, while offering an appropriate response. In mammals, bacterial sensing leads to the production of specific immunoglobulins (Ig), which reach the intestinal lumen as secretory Ig (SIg). Recent work has shed more light on the mechanisms by which SIg can shape bacterial repertoires and contribute to regulating host metabolism. In parallel, bacterial metabolites modulate Ig production and secretion. Here, we present an overview of the current knowledge of the relationship between bacterial metabolites and host SIg, correlating the disruption of this balance with chronic inflammation in humans.

Hierarchical modelling of immunoglobulin coated bacteria in dogs with chronic enteropathy shows reduction in coating with disease remission but marked inter-individual and treatment-response variability

Chronic enteropathies are a common problem in dogs, but many aspects of the pathogenesis remain unknown, making the therapeutic approach challenging in some cases. Environmental factors are intimately related to the development and perpetuation of gastrointestinal disease and the gut microbiome has been identified as a contributing factor. Previous studies have identified dysbiosis and reduced bacterial diversity in the gastrointestinal microbiota of dogs with chronic enteropathies. In this case-controlled study, we use flow cytometry and 16S rRNA sequencing to characterise bacteria highly coated with IgA or IgG in faecal samples from dogs with chronic enteropathy and evaluated their correlation with disease and resolution of the clinical signs. IgA and IgG-coated faecal bacterial counts were significantly higher during active disease compared to healthy dogs and decreased with the resolution of the clinical signs. Characterisation of taxa-specific coating of the intestinal microbiota with IgA and IgG showed marked variation between dogs and disease states, and different patterns of immunoglobulin enrichment were observed in dogs with chronic enteropathy, particularly for Erysipelotrichaceae, Clostridicaceae, Enterobacteriaceae, Prevotellaceae and Bacteroidaceae, families. Although, members of these bacterial groups have been associated with strong immunogenic properties and could potentially constitute important biomarkers of disease, their significance and role need to be further investigated.

Human gut-associated lymphoid tissues (GALT); diversity, structure, and function

Gut-associated lymphoid tissues (GALT) are the key antigen sampling and adaptive immune inductive sites within the intestinal wall. Human GALT includes the multi-follicular Peyer's patches of the ileum, the vermiform appendix, and the numerous isolated lymphoid follicles (ILF) which are distributed along the length of the intestine. Our current understanding of GALT diversity and function derives primarily from studies in mice, and the relevance of many of these findings to human GALT remains unclear. Here we review our current understanding of human GALT diversity, structure, and composition as well as their potential for regulating intestinal immune responses during homeostasis and inflammatory bowel disease (IBD). Finally, we outline some key remaining questions regarding human GALT, the answers to which will advance our understanding of intestinal immune responses and provide potential opportunities to improve the treatment of intestinal diseases.

Distribution and Cytokine Profile of Peripheral B Cell Subsets Is Perturbed in Pediatric IBD and Partially Restored During a Successful IFX Therapy

BACKGROUND

The role of B cells in inflammatory bowel disease (IBD) is ambiguous, as B cells may have both pathogenic and protective functions in IBD. We studied B cell subsets before and after initiation of an anti-tumor necrosis factor alpha (anti-TNFα) therapy in pediatric IBD. The aim of the study was to examine the behavior of B cells in pediatric IBD patients undergoing an anti-TNFα therapy and, more specifically, to clarify their association with a successful or an unsuccessful infliximab (IFX) treatment.

METHODS

A total of N = 42 pediatric IBD patients (Crohn disease, n = 30; ulcerative colitis, n = 12) for whom an anti-TNFα therapy with and without a concomitant azathioprine (AZA) medication was administered were recruited. Fourteen healthy age-matched children served as control patients. Blood samples were collected before initiation of the anti-TNFα therapy, before the fourth infusion at the end of the induction phase, and after 6 and 12 months under therapy maintenance. Flow cytometry (CD20, CD27, CD38, CD138) and intracellular staining (interleukin 10 [IL10], TNFα, granzyme B) were performed. Responders to successful IFX therapy were classified exhibiting a fecal calprotectin level of below 100 µg/g or achieving levels of <10% of the baseline value at initiation than at the end of the 12-month follow-up period.

RESULTS

Before initiation of anti-TNFα therapy, flow cytometry revealed increased percentages of naïve B cells whereas transitional B cells were reduced compared with those in the healthy control patients. The IL10-producing B cells of both ulcerative colitis and Crohn disease patients were reduced at the initiation of IFX therapy, whereas TNFα-producing transitional CD24hiCD38hi B cells in ulcerative colitis patients were increased compared with those in healthy control patients. After 12 months of therapy, we detected a significant increase of IL10-producing transitional B cells in responding patients.The IFX trough levels in the responding patients showed a significant increase until 6 months after IFX initiation, attaining mean values of 9.9 µg/mL, whereas the IFX dosage was significantly lower than that in the nonresponding patients. The IFX trough levels in AZA-treated patients reached earlier therapeutic levels than in patients without AZA comedication, whereas during the course of the IFX therapy, comedication with AZA had no significant effect on the outcome.

CONCLUSIONS

Attaining a normalization of IL10 production among CD24hiCD38hi B cells after 12 months of therapy may represent additional information about the reconstitution of a patient's immune system in responding patients. The achievement of an IFX trough level of ~10 µg/mL at 6 months of treatment is associated with a successful anti-TNFα therapy. In addition, AZA comedication supports an earlier achievement of therapeutic IFX trough levels.

IgA nephropathy in association with inflammatory bowel diseases: results from a national study and systematic literature review

BACKGROUND

Little is known about clinical characteristics and kidney outcome in patients with biopsy-proven immunoglobulin A nephropathy (IgAN) in a context of inflammatory bowel disease (IBD).

METHODS

We conducted a retrospective multicenter study with centralized histological review, to analyze the presentation, therapeutic management and outcome of 24 patients suffering from IBD associated IgAN relative to a cohort of 134 patients with primary IgAN without IBD.

RESULTS

Crohn's disease and ulcerative colitis accounted for 75% and 25% of IBD-associated IgAN cases, respectively. IBD was diagnosed before IgAN in 23 cases (a mean of 9 years previously) and was considered active at IgAN onset in 23.6% of patients. Hypertension was present in 41.7% of patients. Urinary protein-to-creatinine ratio exceeded 100 mg/mmol in 70.8% of patients (mean: 254 mg/mmol). Estimated glomerular filtration rate (eGFR) exceeded 60 ml/min/1.73m2 in 13/24 patients and only one patient required dialysis. In the Oxford MEST-C classification of renal biopsies, 57% were M1, 48% E1, 76% S1, 57% T1+T2 and 38% C1+C2. Steroids were administered in 50% of cases. After a mean follow-up of 7.2 years, four patients (16.7%) had a poor kidney outcome: end-stage renal disease (n = 3) or a > 50% decrease in eGFR from initial values (n = 1). A similar evolution was observed in patients with primitive IgAN.

CONCLUSIONS

This first case series suggests that IBD-associated IgAN have frequent inflammatory lesions at onset and variable long-term outcome.

Sestrin3 enhances macrophage-mediated generation of T helper 1 and T helper 17 cells in a mouse colitis model

Intestinal macrophages participate in the pathogenesis of inflammatory bowel diseases (IBDs) through secreting pro-inflammatory and tissue-damaging factors as well as inducing the differentiation of T helper 1 (Th1) and T helper 17 (Th17) cells. Elucidating the regulatory mechanisms of intestinal macrophage activity in IBDs is important for developing new therapeutic approaches. In the current study, the expression of Sestrins in myeloid cells and lymphocytes in colonic lamina propria (LP) was evaluated in a murine acute colitis model. We found that Sestrin3 was significantly up-regulated in LP macrophages by the colonic LP microenvironment. In the in vitro experiments, lentivirus-mediated Sestrin3 knockdown significantly reduced the production of IL-12 and IL-23 in activated macrophages, in addition to decreasing the expression of classical pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. Additionally, Sestrin3 knockdown impaired macrophage-mediated generation of Th1 and Th17 cells from CD4+ T cells, probably through up-regulating the phosphorylation of mechanistic target of rapamycin complex 1 (mTORC1) in macrophages. In the in vivo experiments, adoptive transfer of Sestrin3-deficient macrophages alleviated the generation of Th1 and Th17 cells in the colonic LP and mesenteric lymph nodes. Furthermore, the adoptive transfer mitigated the severity of colitis, as demonstrated by lower production of pro-inflammatory cytokines and fewer tissue lesions in the colon. Our study suggests that Sestrin3 might be crucial for macrophage-mediated generation of pathogenic Th1 and Th17 cells in IBDs.

Ocrelizumab-Induced Severe Colitis

We report a case of severe ocrelizumab (anti-CD20 monoclonal antibody) induced colitis in a 43-year-old woman with multiple sclerosis leading to total colectomy after failing medical therapy. Histology of the colectomy was consistent with medication-induced colitis.

Identification of Immune Cell Landscape and Construction of a Novel Diagnostic Nomogram for Crohn's Disease

Crohn’s disease (CD) has an increasing incidence and prevalence worldwide. The etiology of CD remains unclear and there is no gold standard for diagnosis. The dysregulated immune response and different infiltration status of immune cells are critical for CD pathogenesis; therefore, it is important to provide an overview of immune-cell alterations in CD and explore a novel method for auxiliary diagnosis. Here we analyzed microarray datasets from Gene Expression Omnibus (GEO), and an extended version of Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORTx) was utilized to estimate the fraction of 22 types of immune cells. Differentially expressed genes (DEGs) and a protein-protein interaction (PPI) network were identified, and we performed gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) to identify differentially regulated pathways in CD. Least absolute shrinkage and selection operator (LASSO) regression was conducted to filter features, and a diagnostic nomogram based on logistic regression was built and validated in an independent validation cohort. In the derivation cohort, we found a proportion of 17 immune-cell types to be significantly altered between CD and healthy controls and a total of 150 DEGs were identified, which were mostly related to the immune response. Among the 15 hub genes based on the PPI network, C-X-C chemokine ligand 8 (CXCL8) and interleukin-1B (IL-1B) showed the highest degree of interaction. Additionally, GSEA and GSVA identified five significantly enriched pathways, among which the nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway was critical in the CD development. Furthermore, six variables comprising of CXCL8, IL-1B, M1 macrophages, regulatory T cells, CD8⁺ T cells, and plasma cells were identified by LASSO regression and incorporated into a logistic regression model. The nomogram displayed a good prediction, with a 0.915 area under the receiver operating curve (AUC) and a C-index of 0.915 [95% confidence interval (CI): 0.875–0.955]. Similar results were found in the validation cohort, with an AUC of 0.884 and a 0.884 C-index (95% CI: 0.843–0.924). These results provide novel in silico insight into cellular and molecular characteristics of CD and potential biomarkers for diagnosis and targeted therapy.

North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Position Paper on the Evaluation and Management for Patients With Very Early-onset Inflammatory Bowel Disease

The rate of pediatric inflammatory bowel disease (IBD) has been increasing over the last decade and this increase has occurred most rapidly in the youngest children diagnosed <6 years, known as very early-onset inflammatory bowel disease (VEO-IBD). These children can present with more extensive and severe disease than older children and adults. The contribution of host genetics in this population is underscored by the young age of onset and the distinct, aggressive phenotype. In fact, monogenic defects, often involving primary immunodeficiency genes, have been identified in children with VEO-IBD and have led to targeted and life-saving therapy. This position paper will discuss the phenotype of VEO-IBD and outline the approach and evaluation for these children and what factors should trigger concern for an underlying immunodeficiency. We will then review the immunological assays and genetic studies that can facilitate the identification of the underlying diagnosis in patients with VEO-IBD and how this evaluation may lead to directed therapies. The position paper will also aid the pediatric gastroenterologist in recognizing when a patient should be referred to a center specializing in the care of these patients. These guidelines are intended for pediatricians, allied health professionals caring for children, pediatric gastroenterologists, pediatric pathologists, and immunologists.

NKp46+ lamina propria natural killer cells undergo metabolic reprogramming in a mouse experimental colitis model

OBJECTIVE

Both innate and adaptive immune system play important roles in the onset and progression of inflammatory bowel diseases (IBDs). However, the significance of natural killer (NK) cells for IBDs remains unclear. To understand the biology of colonic lamina propria natural killer (LPNK) cells in IBDs, we characterized LPNK cell metabolism in a murine acute colitis model.

METHODS

C57BL/6J mice were fed with 3% dextran sulfate sodium to establish the acute colitis model. Colonic LPNK cells were isolated from mice through flow cytometry. The expression of metabolic genes in LPNK cells was analyzed by transcriptome sequencing and quantitative RT-PCR. Glucose uptake, Seahorse assay, and ATP assay were conducted to assess the metabolic status of LPNK cells. Phos-flow assay was performed to evaluate cell signaling pathways in LPNK cells. In vitro stimulation and cytotoxicity assay were conducted to measure the function of LPNK cells.

RESULTS

In acute colitis, LPNK cells upregulated the expression of genes related to glycolysis and oxidative phosphorylation (oxphos), and enhanced glucose uptake capability. Intracellular ATP production, glycolysis and oxphos in LPNK cells were also promoted in acute colitis. mTORC1 signaling was essential for the metabolic reprogramming in LPNK cells in acute colitis. Although LPNK cells of diseased mice exhibited equivalent cytokine profile to normal LPNK cells upon stimulation with phorbol ester or IL-2, LPNK cells of diseased mice were more cytotoxic to target cells than normal LPNK cells.

CONCLUSIONS

LPNK cells undergo metabolic reprogramming which might be a response to upcoming microbial infection in acute colitis.

B Cells and Antibodies in Kawasaki Disease

The etiology of Kawasaki disease (KD), the leading cause of acquired heart disease in children, is currently unknown. Epidemiology supports a relationship of KD to an infectious disease. Several pathological mechanisms are being considered, including a superantigen response, direct invasion by an infectious etiology or an autoimmune phenomenon. Treating affected patients with intravenous immunoglobulin is effective at reducing the rates of coronary aneurysms. However, the role of B cells and antibodies in KD pathogenesis remains unclear. Murine models are not clear on the role for B cells and antibodies in pathogenesis. Studies on rare aneurysm specimens reveal plasma cell infiltrates. Antibodies generated from these aneurysmal plasma cell infiltrates showed cross-reaction to intracellular inclusions in the bronchial epithelium of a number of pathologic specimens from children with KD. These antibodies have not defined an etiology. Notably, a number of autoantibody responses have been reported in children with KD. Recent studies show acute B cell responses are similar in children with KD compared to children with infections, lending further support of an infectious disease cause of KD. Here, we will review and discuss the inconsistencies in the literature in relation to B cell responses, specific antibodies, and a potential role for humoral immunity in KD pathogenesis or diagnosis.

Goji Berry Modulates Gut Microbiota and Alleviates Colitis in IL-10-Deficient Mice

SCOPE

This study examines the beneficial effects of Goji berry against spontaneous colitis and its prebiotic role in IL-10-deficient mice.

METHODS

IL-10-deficient mice are assigned to a standard rodent diet (control) or a control diet supplemented with Goji (1% of dry feed weight) for 10 weeks, at which point colonic tissues and fecal contents are collected.

RESULTS

Goji supplementation decreases colonic pathobiological scores and mRNA expression of Il17a and Tgfb1, while it enhances Muc1 expression and fecal IgA content. Illumina MiSeq sequencing reveals that Goji supplementation increases Actinobacteria phylum, resulting in a bloom of Bifidobacteria in gut microbiota. Additionally, dietary Goji promotes butyrate-producing bacteria including Lachnospiraceae-Ruminococcaceae family and Roseburia spp. under Clostridium cluster XIVa. Furthermore, butyrate-producers Clostridium leptum and its dominant constituent Fecalibacterium prazusnitzii are markedly increased in the Goji group. Moreover, the gene-encoding butyryl-coenzyme A CoA transferase, a key enzyme responsible for butyrate synthesis in butyrate-producing bacteria, is increased sixfold in the fecal samples of Goji group associated with increased fecal butyrate content.

CONCLUSION

Data collectively show that dietary Goji results in the blooming of Bifidobacteria and butyrate-producing bacteria. These bacteria may cross-feed each other, conferring preventative effects against colitis in IL-10-deficient mice.

Treatment of experimental colitis by endometrial regenerative cells through regulation of B lymphocytes in mice

BACKGROUND

Endometrial regenerative cells (ERCs), a novel type of mesenchymal-like stem cell derived from menstrual blood, have been recently evaluated as an attractive candidate source in ulcerative colitis (UC); however, the mechanism is not fully understood. The present study was designed to investigate the effects of ERCs, especially on B-cell responses in UC.

METHODS

In this study, colitis was induced by administering 3% dextran sodium sulfate (DSS) via free drinking water for 7 days to BALB/c mice. In the treated group, mice were injected intravenously with 1 × 10⁶ ERCs on days 2, 5, and 8 after DSS induction. Therapeutic effects were assessed by monitoring body weight, disease activity, and pathological changes. Subpopulations of lymphocytes were determined by flow cytometry. IgG deposition in the colon was examined by immunohistochemistry staining. Cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA), Western blot, or polymerase chain reaction (PCR) analysis. Adoptive transfer of regulatory B cells (Bregs) into colitis mice was performed.

RESULTS

Here, we demonstrated that ERC treatment prolonged the survival of colitis mice and attenuated disease activity with fewer pathological changes in colon tissue. ERCs decreased the proportion of immature plasma cells in the spleen and IgG deposition in the colon. On the other hand, ERCs increased the production of Bregs and the interleukin (IL)-10 level. Additionally, adoptive transferred Bregs exhibited significant therapeutic effects on colitis mice.

CONCLUSIONS

In conclusion, our results unravel the therapeutic role of ERCs on experimental colitis through regulating the B-lymphocyte responses.

Efficient long-term depletion of CD20+ B cells by rituximab does not affect gut-resident plasma cells

The vast majority of antibody-producing B cells are located within the gastrointestinal tract and are key players in maintaining homeostasis. The failure of rituximab, a potent B cell-depleting agent, to ameliorate ulcerative colitis in a single clinical trial has dampened enthusiasm to study B cells in patients with inflammatory bowel disease (IBD). However, several lines of evidence suggest that intestinal B cells may be affected in IBD. Additionally, the pathophysiological mechanisms underlying rituximab's lack of efficacy in IBD remain unclear. Here, on the basis of detailed immunophenotyping of a patient who underwent a colonoscopy 6 months after the end of rituximab-based therapy, we observed that rituximab did not deplete colon-resident plasma cells (PCs) while ablating all CD20⁺ B cells in tissues and in the circulation. On the basis of these observations, we propose that one factor underlying the lack of efficacy of rituximab relates to the fact that it does not affect the entire B cell compartment in tissues, sparing the intestinal-resident PCs while effectively depleting CD20⁺ B cell populations. Thus, we contend that, despite the results of the Rituximab study, there is a need for more intensive B cell-oriented research in inflammatory disorders, including IBD.

Inflammatory cells implicated in neoplasia development in idiopathic inflammatory bowel disease

The inflammatory mechanisms that lead to the clinical symptoms that are grouped under the term inflammatory bowel disease have not been fully characterized. Although a specific mechanism has not been identified, inflammatory bowel disease is believed to be related to an inability by the immune system to shut active inflammation within the intestine. Many contributing factors have been implicated in the disease process. Based on population studies, patients with inflammatory bowel disease have an increased risk for neoplastic development. Although no specific immune cell has been implicated in neoplastic development within this patient population, several immune cells have been implicated as possible etiologies in inflammatory bowel disease. In this review, we will review the clinical evidence about the risk for neoplastic development in inflammatory bowel disease and the current clinical guidelines to survey this patient population. We will also review the pathologic assessment of inflammation within this patient population as well the underlying immune cells and cytokines that have been implicated in the etiology of inflammatory bowel disease.

Human Gut Microbiota: Toward an Ecology of Disease

Composed of trillions of individual microbes, the human gut microbiota has adapted to the uniquely diverse environments found in the human intestine. Quickly responding to the variances in the ingested food, the microbiota interacts with the host via reciprocal biochemical signaling to coordinate the exchange of nutrients and proper immune function. Host and microbiota function as a unit which guards its balance against invasion by potential pathogens and which undergoes natural selection. Disturbance of the microbiota composition, or dysbiosis, is often associated with human disease, indicating that, while there seems to be no unique optimal composition of the gut microbiota, a balanced community is crucial for human health. Emerging knowledge of the ecology of the microbiota-host synergy will have an impact on how we implement antibiotic treatment in therapeutics and prophylaxis and how we will consider alternative strategies of global remodeling of the microbiota such as fecal transplants. Here we examine the microbiota-human host relationship from the perspective of the microbial community dynamics.

Molecular mechanisms by which casein glycomacropeptide maintains internal homeostasis in mice with experimental ulcerative colitis

OBJECTIVES

The aim of this study was to elucidate the molecular mechanisms by which food-derived casein glycomacropeptide (CGMP) maintains internal homeostasis in the intestinal mucosa and to investigate the effects of CGMP on the intestinal mucosal immunological barrier and related signal transduction pathways.

METHODS

In this study, a famoxadone (OXZ)-induced mouse experimental ulcerative colitis (UC) model was built. The experimental UC mice were intragastrically administered milk-derived CGMP for four consecutive days. The molecular mechanisms by which milk-derived CGMP improved and restored the inflammatory status in UC symptoms were elucidated by H&E staining, immunohistochemical staining and western blotting.

RESULTS

The results indicated that CGMP (50 mg/(kg bw·d)) could significantly improve morphological injury to intestinal mucosa in OXZ-induced UC mice to the same extent that did sulfasalazine (SASP, 40 mg/(kg bw·d)), a medicine used to treat UC, in the control group. The study found that CGMP could significantly reduce the expression of Human mucosal addressin cell adhesion molecule-1 (MAdCAM-1), Cluster of differentiation 4 (CD4) and Cluster of differentiation 8 (CD8) in the lamina propria of the intestinal mucosa and significantly stimulate the secretion of sIgA to increase intestinal immunity. Furthermore, CGMP was found to be directly involved in inhibiting the MAPK pathway and activating the TGF-β1/Smad signal transduction cascade, which could maintain immunological regulation of the intestinal mucosa and protect the functions of the intestinal mucosal barrier.

CONCLUSIONS

This study elucidated the molecular mechanisms by which CGMP maintained homeostasis of the intestinal mucosa and further confirmed its pharmaceutical value as a food-derived functional component with promising potential for further exploration/utilization.

MDR1A deficiency restrains tumor growth in murine colitis-associated carcinogenesis

Patients with Ulcerative Colitis (UC) have an increased risk to develop colitis-associated colorectal cancer (CAC). Here, we found that protein expression of ABCB1 (ATP Binding Cassette Subfamily B Member 1) / MDR1 (multidrug resistance 1) was diminished in the intestinal mucosa of patients with active UC with or without CAC, but not in non-UC patients with sporadic colon cancer. We investigated the consequences of ABCB1/MDR1 loss-of-function in a common murine model for CAC (AOM/DSS). Mice deficient in MDR1A (MDR1A KO) showed enhanced intratumoral inflammation and cellular damage, which were associated with reduced colonic tumor size and decreased degree of dysplasia, when compared to wild-type (WT). Increased cell injury correlated with reduced capacity for growth of MDR1A KO tumor spheroids cultured ex-vivo. Gene expression analysis by microarray demonstrated that MDR1A deficiency shaped the inflammatory response towards an anti-tumorigenic microenvironment by downregulating genes known to be important mediators of cancer progression (PTGS2 (COX2), EREG, IL-11). MDR1A KO tumors showed increased gene expression of TNFSF10 (TRAIL), a known inducer of cancer cell death, and CCL12, a strong trigger of B cell chemotaxis. Abundant B220+ B lymphocyte infiltrates with interspersed CD138+ plasma cells were recruited to the MDR1A KO tumor microenvironment, concomitant with high levels of immunoglobulin light chain genes. In contrast, MDR1A deficiency in RAG2 KO mice that lack both B and T cells aggravated colonic tumor progression. MDR1A KO CD19+ B cells, but not WT CD19+ B cells, suppressed growth of colonic tumor-derived spheroids from AOM/DSS-WT mice in an ex-vivo co-culture system, implying that B-cell regulated immune responses contributed to delayed tumor development in MDR1A deficiency. In conclusion, we provide first evidence that loss of ABCB1/MDR1 function may represent an essential tumor-suppressive host defense mechanism in CAC.

Oral manifestations as the first presenting sign of Crohn's disease in a pediatric patient

Crohn’s disease (CD) is a chronic inflammatory disorder affecting the gastrointestinal (GI) tract. Although the GI tract is the primary site of involvement, many patients, particularly in pediatric cases, first present with non-intestinal manifestations, including oral lesions. Oral manifestations of CD in children occur in around 50-80% of cases, and about 30% of CD cases in children occur first in the mouth. Recognizing such oral lesions in the pediatric population, and requesting a biopsy, may expedite the diagnosis of CD. We describe a 15 year old male who presented with oral findings of multiple aphthous ulcers and plaques of pink papules of the buccal vestibule. We highlight the initial pathology findings, including non-caseating granulomas, sialadenitis, and a notable plasmacytosis, from biopsy of the left retromolar pad area, which triggered further testing for CD. We provide discussion of how CD was eventually diagnosed and treated and highlight the significance of the pathological findings in this case as they relate to the pathogenesis of CD.

Key words:Crohn’s disease, Inflammatory bowel disease, Oral manifestations, Pediatric, Granulomatous inflammation, Monotypic plasma cells.

Crohn's disease

Crohn's disease is a chronic inflammatory disease of the gastrointestinal tract, with increasing incidence worldwide. Crohn's disease might result from a complex interplay between genetic susceptibility, environmental factors, and altered gut microbiota, leading to dysregulated innate and adaptive immune responses. The typical clinical scenario is a young patient presenting with abdominal pain, chronic diarrhoea, weight loss, and fatigue. Assessment of disease extent and of prognostic factors for complications is paramount to guide therapeutic decisions. Current strategies aim for deep and long-lasting remission, with the goal of preventing complications, such as surgery, and blocking disease progression. Central to these strategies is the introduction of early immunosuppression or combination therapy with biologicals in high-risk patients, combined with a tight and frequent control of inflammation, and adjustment of therapy on the basis of that assessment (treat to target strategy). The therapeutic armamentarium for Crohn's disease is expanding, and therefore the need to develop biomarkers that can predict response to therapies will become increasingly important for personalised medicine decisions in the near future. In this Seminar, we provide a physician-oriented overview of Crohn's disease in adults, ranging from epidemiology and cause to clinical diagnosis, natural history, patient stratification and clinical management, and ending with an overview of emerging therapies and future directions for research.

The Interplay between Defensins and Microbiota in Crohn's Disease

Crohn's disease (CD) is a chronic inflammation of the intestinal mucosa, characterized by periods of acute recurrence and remission. Depending on the specific region affected, CD is classified as ileal CD or colonic CD. It is largely accepted that the intestinal microbiota is involved in the onset of the pathology. Indeed, a reduced immune tolerance to components of the intestinal commensal microbiota and inflammation of the intestinal barrier typifies patients with CD. Several studies have shown defective expression of intestinal antimicrobial peptides (AMPs) in patients with CD compared to controls, particularly defensins. A reduction in α-defensins is observed in ileal CD, while β-defensins are increased in colonic CD. In addition to an immunological basis, the disease is frequently associated with genetic alterations including mutations of NOD2 gene. Several therapeutic strategies to circumvent the dysfunction observed in CD are currently under investigation. These include the use of delivery systems to administer endogenous AMPs and the engineering of peptidomimetics that could ameliorate the severity of CD. In this review, the role defensins play in CD and the strategies aimed at overcoming bacterial resistance will be discussed.

B Cell-Activating Factor (BAFF)-Targeted B Cell Therapies in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) involve dysregulated immune responses to gut antigens in genetically predisposed individuals. While a better elucidation of IBD pathophysiology has considerably increased the number of treatment options, the need for more effective therapeutic strategies remains a pressing priority. Defects of both non-hematopoietic (epithelial and stromal) and hematopoietic (lymphoid and myeloid) cells have been described in patients with IBD. Within the lymphoid system, alterations of the T cell compartment are viewed as essential in the pathogenesis of IBD. However, growing evidence points to the additional perturbations of the B cell compartment. Indeed, the intestinal lamina propria from IBD patients shows an increased presence of antibody-secreting plasma cells, which correlates with enhanced pro-inflammatory immunoglobulin G production and changes in the quality of non-inflammatory IgA responses. These B cell abnormalities are compounded by the emergence of systemic antibody responses to various autologous and microbial antigens, which predates the clinical diagnosis of IBD and identifies patients with complicated disease. It is presently unclear whether such antibody responses play a pathogenetic role, as B cell depletion with the CD20-targeting monoclonal antibody rituximab did not ameliorate ulcerative colitis in a clinical trial. However, it must be noted that unresponsiveness to rituximab is also observed also in some patients with autoimmune disorders usually responsive to B cell-depleting therapies. In this review, we discussed mechanistic aspects of B cell-based therapies and their potential role in IBD with a special interest on BAFF and BAFF-targeting therapies buoyed by the success of anti-BAFF treatments in rheumatologic disorders.

Ulcerative Colitis Is Characterized by a Decrease in Regulatory B Cells

BACKGROUND AND AIMS

Ulcerative colitis (UC) is characterized by Th2-polarized, B cell responses. However, neither size, composition, nor activity of the Breg compartment in active UC has been evaluated.

METHODS

Peripheral blood of 25 patients with UC, 5 patients with Crohn's disease (CD) and 15 control subjects was examined for Bregs subsets by flow cytometry. Intestinal tissue of 5 patients with UC, 3 patients with CD and 5 control subjects was also examined for Bregs. The levels of serum interleukin (IL)-10, immunoglobulin (Ig), and C-reactive protein (CRP), and the erythrocyte sedimentation rate (ESR) in individual subjects were measured. Interleukin-10 production in B cells isolated from patients with UC was examined. Potential associations between the values of the different measures were analysed by the Spearman correlation test.

RESULTS

Compared with controls, the UC patients had significantly reduced frequencies of CD24(high)CD38(high) and CD5(+) Bregs in peripheral blood as well as in intestinal tissues, accompanied by lower serum IL-10 levels. Interleukin-10 production was significantly decreased in stimulated B cells from patients with UC, whereas patient IL-10(+) B cells were found to be enriched in CD24(high)CD38(high) and CD5(+) B cells. However, increased percentages of CD95(+)-exhausted Bregs were encountered in subsets. Furthermore, Mayo clinic scores, CRP, and ESR in UC patients was negatively correlated with the frequency of Bregs and the IL-10 concentration, whereas these parameters were positively correlated with the frequency of CD95(+)-exhausted Bregs and the IgG levels.

CONCLUSIONS

Active UC is characterized by exhaustion of regulatory control in the B cell compartment.

B Cell-Activating Factor as a New Potential Marker in Inflammatory Bowel Disease

BACKGROUND

B cell-activating factor (BAFF) has been proposed to be a regulator of B cell and T cell immune responses and be associated with inflammatory processes in autoimmunity and B cell malignancies. No study has reported the role of BAFF in inflammatory bowel disease (IBD).

AIMS

The purpose of this study was to investigate expression and concentrations of BAFF in IBD and determine its value to discriminate patients with IBD.

METHODS

Seventy-eight ulcerative colitis (UC) patients, 37 Crohn's disease (CD) patients, 12 irritable bowel syndrome (IBS) patients and 44 healthy controls were recruited. We examined serum and faecal BAFF levels using enzyme-linked immunosorbent assay. Intestinal BAFF expression was analysed in biopsies obtained from IBD patients. Intestinal mucosa localization of BAFF was conducted by immunofluorescence.

RESULTS

The median (25th-75th percentile) serum BAFF concentration (pg/ml) was 1430 (1105-1624) in CD patients, 1472 (1018-1772) in UC patients and 977 (482-1345) in healthy controls. Serum BAFF was 64 % sensitive and 93 % specific for identifying active IBD from healthy controls. The BAFF expression was significantly increased in biopsy specimens from IBD patients. Fecal BAFF concentration was 369 (326-493) pg/ml in CD patients, 542 (358-1758) pg/ml in UC patients, 294 (287-299) pg/ml in IBS patients and 295 (284-309) pg/ml in healthy controls. Fecal BAFF was 90 % sensitive and 96 % specific for identifying active IBD from healthy controls and IBS patients.

CONCLUSION

The novel association between BAFF and IBD seems to identify that BAFF might regulate the inflammatory process in these diseases and it appears to be a potential marker of IBD.

Circulating memory B cells and plasmablasts are associated with the levels of serum immunoglobulin in patients with ulcerative colitis

Humoural immunity is crucial for the pathogenesis of ulcerative colitis (UC), but the precise perturbation of B cell immunity is poorly understood. This study is aimed at evaluating the numbers of different subsets of circulating memory B cells, plasmablasts, and the levels of serum immunoglobulin in UC patients. Total of 23 patients with active UC and 14 healthy controls (HC) were examined for the numbers of different subsets of circulating memory B cells and plasmablasts before and after treatment with mesalazine for 8-12 weeks by flow cytometry. Disease activity was evaluated by the Mayo clinic score. The levels of serum immunoglobulin, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured in individual subjects. In comparison with that in HC, significantly reduced numbers of IgG(+) IgD(-) CD27(+) CD19(+) memory B cells, increased numbers of CD20(-) CD19(+) plasmablast subsets, and higher serum IgG levels were detected in UC patients. The concentrations of serum IgG, the numbers of CD138(+) CD38(+) CD20(-) CD19(+), and IgG(+) CD38(+) CD20(-) CD19(+) plasmablasts were negatively associated with the numbers of IgG(+) IgD(-) CD27(+) CD19(+) memory B cells. Furthermore, the values of Mayo clinic score, CRP, or ESR in UC patients were negatively correlated with the numbers of IgG(+) IgD(-) CD27(+) CD19(+) memory B cells, while positively correlated with the serum IgG levels and the numbers of plasmablast subsets. Following treatment with mesalazine, the numbers of circulating IgG(+) IgD(-) CD27(+) CD19(+) memory B cells were significantly increased, while the numbers of CD138(+) CD38(+) CD20(-) CD19(+) and IgG(+) CD38(+) CD20(-) CD19(+) plasmablasts were reduced in UC patients. These decreased IgG(+) IgD(-) CD27(+) CD19(+) memory B cells and increased plasmablasts may be involved in the pathogenic process of UC.

Supplemental fermented plant product ('Manda Koso') reduces succinate and deoxycholate, as well as elevates IgA and mucin levels, in rats fed a high-fat diet

‘Manda Koso’ is a commercial fermented plant product (FPP) made from 53 types of fruits and vegetables that have been fermented for >3 years and 3 months. We hypothesized that FPP intake improves the luminal environment of rats fed a high-fat diet. Thus, the present study examined the effects of consumption of 5% FPP diet for 3 weeks on colonic luminal parameters in rats fed a 30% beef tallow diet. Food intake and body weight gain were unaffected. Consumption of the FPP diet did not influence the proportions of Bifidobacterium, Lactobacillus, Bacteroides, Prevotella or Clostridium in cecal contents. However, the FPP diet caused a significant reduction (−88%) in the level of cecal succinate, a putative inflammatory signal (P<0.01), but did not affect the levels of n-butyrate, propionate, acetate and lactate. The fecal levels of deoxycholate and hyodeoxycholate, which are toxic bile acids, were also significantly reduced by the FPP diet (P<0.05). The FPP diet significantly increased fecal immunoglobulin A and mucins responsible for intestinal immune and barrier functions (P<0.05). The results suggest that the consumption of FPP is beneficial for the colonic luminal environment in rats fed a high-fat diet.

Immune deficiency vs. immune excess in inflammatory bowel diseases-STAT3 as a rheo-STAT of intestinal homeostasis

Genome-wide association studies have provided many genetic alterations, conferring susceptibility to multifactorial polygenic diseases, such as inflammatory bowel diseases. Yet, how specific genetic alterations functionally affect intestinal inflammation often remains elusive. It is noteworthy that a large overlap of genes involved in immune deficiencies with those conferring inflammatory bowel disease risk has been noted. This has provided new arguments for the debate on whether inflammatory bowel disease arises from either an excess or a deficiency in the immune system. In this review, we highlight the functional effect of an inflammatory bowel disease-risk allele, which cannot be deduced from genome-wide association studies data alone. As exemplified by the transcription factor signal transducer and activator of transcription 3 (STAT3), we show that a single gene can have a plethora of effects in various cell types of the gut. These effects may individually contribute to the restoration of intestinal homeostasis on the one hand or pave the way for excessive immunopathology on the other, as an inflammatory "rheo-STAT".

Inflammatory bowel disease

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal's history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.