Spondyloarthritis in First-Degree Relatives and Spouses of Patients with Inflammatory Bowel Disease: A Nationwide Population-based Cohort Study from Sweden.

BACKGROUND AND AIMS: Register-based research suggests a shared pathophysiology between inflammatory bowel disease [IBD] and spondyloarthritis [SpA], but the role of familial [genetic and environmental] factors in this shared susceptibility is largely unknown. We aimed to compare the risk of SpA in first-degree relatives [FDRs] and spouses of IBD patients with FDRs and spouses of matched, population-based, reference individuals. METHODS: We identified 147 080 FDRs and 25 945 spouses of patients with incident IBD [N = 39 203] during 2006-2016, and 1 453 429 FDRs and 258 098 spouses of matched reference individuals [N = 390 490], by linking nationwide Swedish registers and gastrointestinal biopsy data. Study participants were followed 1987-2017. Cox regression was used to estimate hazard ratios [HRs] of SpA. RESULTS: During follow-up, 2430 FDRs of IBD patients [6.5/10 000 person-years] and 17 761 FDRs of reference individuals [4.8/10 000 person-years] were diagnosed with SpA, corresponding to an HR of 1.35 [95% CI:1.29, 1.41]. In subgroup analyses, the increased risk of SpA was most pronounced in FDRs of Crohn's disease patients [HR = 1.44; 95% CI:1.34,1.5 6] and of IBD patients aged <18 years at diagnosis [HR = 1.46; 95% CI: 1.27, 1.68]. IBD patients' spouses also had a higher SpA rate than reference individuals' spouses, but the difference was less pronounced [4.3 vs 3.5/10 000 person-years; HR = 1.22; 95% CI:1.09, 1.37]. No subgroup-specific risk pattern was identified among spouses. CONCLUSIONS: The observed shared familial risks between IBD and SpA support shared genetic factors in their pathogenesis. However, spouses of IBD patients were also at increased risk for SpA, reflecting the influence of environmental exposures or similarities in health-seeking patterns.

Association Between Inflammatory Bowel Disease and Spondyloarthritis: Findings from a Nationwide Study in Sweden.

BACKGROUND AND AIMS: Inflammatory bowel disease [IBD] has been associated with spondyloarthritis [SpA], but population-based estimates are scarce. Here we compare the occurrence of SpA before and after a diagnosis of IBD with the general population, overall and by IBD subtype and age. METHODS: We used a nationwide register-based cohort study of 39 203 patients diagnosed with IBD during 2006-2016, identified from Swedish registers and gastrointestinal biopsy data, and 390 490 matched reference individuals from the general population. Conditional logistic regression models were used to estimate odds ratios [ORs] for a prior [prevalent] SpA diagnosis and conditional Cox regression to calculate hazard ratios [HRs] for a subsequent [incident] SpA diagnosis in IBD patients. RESULTS: IBD patients were more likely to have prevalent SpA at IBD diagnosis [2.5%] compared with reference individuals [0.7%] with an OR of 3.48 [95% CI: 3.23, 3.75]. They also more often received an incident diagnosis of SpA; during 23 341 934 person-years of follow-up in IBD patients, there were 1030 SpA events [5.0/1000 person-years] compared with 1524 SpA events in the reference group [0.72/1000 person-years], corresponding to an HR of 7.15 [95% CI: 6.60, 7.75]. In subgroup analyses, associations were most pronounced among patients with Crohn's disease ([OR = 5.20; 95% CI: 4.59, 5.89], and [HR = 10.55; 95% CI: 9.16, 12.15]) and paediatric onset IBD ([OR = 3.63; 95% CI: 2.35, 5.59] and [HR = 15.03; 95% CI: 11.01, 20.53]). CONCLUSIONS: IBD patients more frequently experience SpA both before and after the diagnosis of IBD compared with the general population, supporting evidence of a shared pathophysiology. The variation in SpA comorbidity, across IBD subtypes and age groups, calls for targeted approaches to facilitate timely diagnosis and intervention.

Perfluoroalkyl substances are increased in patients with late-onset ulcerative colitis and induce intestinal barrier defects ex vivo in murine intestinal tissue.

BACKGROUND: Environmental factors are strongly implicated in late-onset of inflammatory bowel disease. Here, we investigate whether high levels of perfluoroalkyl substances are associated with (1) late-onset inflammatory bowel disease, and (2) disturbances of the bile acid pool. We further explore the effect of the specific perfluoroalkyl substance perfluorooctanoic acid on intestinal barrier function in murine tissue. METHODS: Serum levels of perfluoroalkyl substances and bile acids were assessed by ultra-performance liquid chromatography coupled to a triple-quadrupole mass spectrometer in matched samples from patients with ulcerative colitis (n = 20) and Crohn's disease (n = 20) diagnosed at the age of ≥55 years. Age and sex-matched blood donors (n = 20), were used as healthy controls. Ex vivo Ussing chamber experiments were performed to assess the effect of perfluorooctanoic acid on ileal and colonic murine tissue (n = 9). RESULTS: The total amount of perfluoroalkyl substances was significantly increased in patients with ulcerative colitis compared to healthy controls and patients with Crohn's disease (p < .05). Ex vivo exposure to perfluorooctanoic acid induced a significantly altered ileal and colonic barrier function. The distribution of bile acids, as well as the correlation pattern between (1) perfluoroalkyl substances and (2) bile acids, differed between patient and control groups. DISCUSSION: Our results demonstrate that perfluoroalkyl substances levels are increased in patients with late-onset ulcerative colitis and may contribute to the disease by inducing a dysfunctional intestinal barrier.

Infliximab restores colonic barrier to adherent-invasive E. coli in Crohn's disease via effects on epithelial lipid rafts.

OBJECTIVE: Infliximab is important in the therapeutic arsenal of Crohn's disease (CD). However, its effect on mucosal barrier function is not fully understood. Adherent-invasive Escherichia coli (AIEC) are important in CD pathophysiology, but the transmucosal uptake routes are partly unknown. We investigated effects of infliximab on uptake of colon-specific AIEC HM427 across CD colonic mucosa. MATERIALS AND METHODS: Endoscopic biopsies from non-inflamed colon of seven patients with CD, before and after two infliximab infusions, and eight non-inflammation controls, were mounted in Ussing chambers. Paracellular permeability (51Cr-EDTA) and transmucosal passage of GFP-expressing HM427 were studied. Mechanisms of HM427 transepithelial transport were investigated in Caco-2 monolayers treated with TNF, in the presence of infliximab and/or endocytosis inhibitors. RESULTS: Before infliximab treatment, colonic passage of HM427 [CD: 2475 CFU (450-3000); controls 1163(225-1950)] and 51Cr-EDTA permeability were increased in CD (p < .05), but were restored to control levels by infliximab (CD: 150 (18.8-1069)). In TNF-exposed Caco-2 monolayers HM427 transport and lipid rafts/HM427 co-localization was decreased by infliximab. The lipid raft inhibitor methyl-ß-cyclodextrin decreased HM427 transport. CONCLUSION: Infliximab restored the colonic barrier to AIEC in CD; an effect partially mediated by blocking lipid rafts in epithelial cells. This ability likely contributes to infliximab's clinical efficacy in colonic CD.

Gut Barrier Dysfunction-A Primary Defect in Twins with Crohn's Disease Predominantly Caused by Genetic Predisposition.

Background and Aims: The aetiology of Crohn's disease is poorly understood. By investigating twin pairs discordant for Crohn's disease, we aimed to assess whether the dysregulated barrier represents a cause or a consequence of inflammation and to evaluate the impact of genetic predisposition on barrier function. Methods: Ileal biopsies from 15 twin pairs discordant for Crohn's disease [monozygotic n = 9, dizygotic n = 6] and 10 external controls were mounted in Ussing chambers to assess paracellular permeability to 51Chromium [Cr]-EDTA and trancellular passage to non-pathogenic E. coli K-12. Experiments were performed with and without provocation with acetylsalicylic acid. Immunofluorescence and ELISA were used to quantify the expression level of tight junction proteins. Results: Healthy co-twins and affected twins displayed increased 51Cr-EDTA permeability at 120 min, both with acetylsalicylic acid [p < 0.001] and without [p < 0.001] when compared with controls. A significant increase in 51Cr-EDTA flux was already seen at 20 min in healthy monozygotic co-twins compared with controls [p≤0.05] when stratified by zygosity, but not in healthy dizygotic co-twins. No difference in E. coli passage was observed between groups. Immunofluorescence of the tight junction proteins claudin-5 and tricellulin showed lower levels in healthy co-twins [p < 0.05] and affected twins [p < 0.05] compared with external controls, while ELISA only showed lower tricellulin in Crohn's disease twins [p < 0.05]. Conclusion: Our results suggest that barrier dysfunction is a primary defect in Crohn's disease, since changes were predominantly seen in healthy monozygotic co-twins. Passage of E. coli seems to be a consequence of inflammation, rather than representing a primary defect.

A ß-Glucan-Based Dietary Fiber Reduces Mast Cell-Induced Hyperpermeability in Ileum From Patients With Crohn's Disease and Control Subjects.

Background: Administration of ß-glucan has shown immune-enhancing effects. Our aim was to investigate whether ß-glucan could attenuate mast cell (MC)-induced hyperpermeability in follicle-associated epithelium (FAE) and villus epithelium (VE) of patients with Crohn's disease (CD) and in noninflammatory bowel disease (IBD)-controls. Further, we studied mechanisms of ß-glucan uptake and effects on MCs in vitro. Methods: Segments of FAE and VE from 8 CD patients and 9 controls were mounted in Ussing chambers. Effects of the MC-degranulator compound 48/80 (C48/80) and yeast-derived ß-1,3/1,6 glucan on hyperpermeability were investigated. Translocation of ß-glucan and colocalization with immune cells were studied by immunofluorescence. Caco-2-cl1- and FAE-cultures were used to investigate ß-glucan-uptake using endocytosis inhibitors and HMC-1.1 to study effects on MCs. Results: ß-glucan significantly attenuated MC-induced paracellular hyperpermeability in CD and controls. Transcellular hyperpermeability was only significantly attenuated in VE. Baseline paracellular permeability was higher in FAE than VE in both groups, P<0.05, and exhibited a more pronounced effect by C48/80 and ß-glucan P<0.05. No difference was observed between CD and controls. In vitro studies showed increased passage, P<0.05, of ß-glucan through FAE-culture compared to Caco-2-cl1. Passage was mildly attenuated by the inhibitor methyl-ß-cyclodextrin. HMC-1.1 experiments showed a trend to decreasing MC-degranulation and levels of TNF-α but not IL-6 by ß-glucan. Immunofluorescence revealed more ß-glucan-uptake and higher percentage of macrophages and dendritic cells close to ß-glucan in VE of CD compared to controls. Conclusions: We demonstrated beneficial effects of ß-glucan on intestinal barrier function and increased ß-glucan-passage through FAE model. Our results provide important and novel knowledge on possible applications of ß-glucan in health disorders and diseases characterized by intestinal barrier dysfunction.

Targeting mitochondria-derived reactive oxygen species to reduce epithelial barrier dysfunction and colitis.

Epithelial permeability is often increased in inflammatory bowel diseases. We hypothesized that perturbed mitochondrial function would cause barrier dysfunction and hence epithelial mitochondria could be targeted to treat intestinal inflammation. Mitochondrial dysfunction was induced in human colon-derived epithelial cell lines or colonic biopsy specimens using dinitrophenol, and barrier function was assessed by transepithelial flux of Escherichia coli with or without mitochondria-targeted antioxidant (MTA) cotreatment. The impact of mitochondria-targeted antioxidants on gut permeability and dextran sodium sulfate (DSS)-induced colitis in mice was tested. Mitochondrial superoxide evoked by dinitrophenol elicited significant internalization and translocation of E. coli across epithelia and control colonic biopsy specimens, which was more striking in Crohn's disease biopsy specimens; the mitochondria-targeted antioxidant, MitoTEMPO, inhibited these barrier defects. Increased gut permeability and reduced epithelial mitochondrial voltage-dependent anion channel expression were observed 3 days after DSS. These changes and the severity of DSS-colitis were reduced by MitoTEMPO treatment. In vitro DSS-stimulated IL-8 production by epithelia was reduced by MitoTEMPO. Metabolic stress evokes significant penetration of commensal bacteria across the epithelium, which is mediated by mitochondria-derived superoxide acting as a signaling, not a cytotoxic, molecule. MitoTEMPO inhibited this barrier dysfunction and suppressed colitis in DSS-colitis, likely via enhancing barrier function and inhibiting proinflammatory cytokine production. These novel findings support consideration of MTAs in the maintenance of epithelial barrier function and the management of inflammatory bowel diseases.

Indomethacin-induced translocation of bacteria across enteric epithelia is reactive oxygen species-dependent and reduced by vitamin C.

The enteric epithelium must absorb nutrients and water and act as a barrier to the entry of luminal material into the body; this barrier function is a key component of innate immunity. Nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy occurs via inhibition of prostaglandin synthesis and perturbed epithelial mitochondrial activity. Here, the direct effect of NSAIDs [indomethacin, piroxicam (cyclooxygenase 1 and 2 inhibitors), and SC-560 (a cyclooxygenase 1 inhibitor)] on the barrier function of human T84 epithelial cell line monolayers was assessed by transepithelial electrical resistance (TER) and internalization and translocation of a commensal Escherichia coli. Exposure to E. coli in the presence and absence of drugs for 16 h reduced TER; however, monolayers cotreated with E. coli and indomethacin, but not piroxicam or SC-560, displayed significant increases in internalization and translocation of the bacteria. This was accompanied by increased reactive oxygen species (ROS) production, which was also increased in epithelia treated with E. coli only. Colocalization revealed upregulation of superoxide synthesis by mitochondria in epithelia treated with E. coli + indomethacin. Addition of antioxidants (vitamin C or a green tea polyphenol, epigallocathechin gallate) quenched the ROS and prevented the increase in E. coli internalization and translocation evoked by indomethacin, but not the drop in TER. Evidence of increased apoptosis was not observed in this model. The data implicate epithelial-derived ROS in indomethacin-induced barrier dysfunction and show that a portion of the bacteria likely cross the epithelium via a transcellular pathway. We speculate that addition of antioxidants as dietary supplements to NSAID treatment regimens would reduce the magnitude of decreased barrier function, specifically the transepithelial passage of bacteria.

Combined polymorphisms in genes encoding the inflammasome components NALP3 and CARD8 confer susceptibility to Crohn's disease in Swedish men.

OBJECTIVES: Crohn's disease (CD) is characterized by overproduction of proinflammatory cytokines like interleukin (IL)-1beta. Production of mature IL-1beta is dependent on a caspase-1-activating protein complex called the NALP3 inflammasome, composed of NALP3, ASC, and CARD8. NALP3 shares structural similarities with Nod2, and both of these proteins are required for bacteria-induced IL-1beta secretion. The combination of the polymorphisms CARD8 (C10X)and NALP3 (Q705K) was recently shown to be associated with rheumatoid arthritis.Our aim was to investigate whether these combined polymorphisms play a role in the susceptibility to CD. METHODS: The study included 498 CD patients in two cohorts from different regions and 742 control individuals from a Swedish population. DNA was isolated from whole blood. Polymorphisms of (Q705K) NALP3 and (C10X) CARD8, as well as the Nod2 variants, R702W and G908R, were genotyped using the Taqman single nucleotide polymorphism assay. The Nod2 frameshift mutation, L1007fs, was detected by Megabace SNuPe genotyping. RESULTS: Our results show that men who have both the C10X and Q705K alleles in CARD8 and NALP3, and who express wild-type alleles of Nod2 are at an increased risk of developing CD (odds ratio, OR: 3.40 range: 1.32-8.76); P = 0.011). No association with these polymorphisms was found in women (OR: 0.89 (range: 0.44-1.77); P = 0.74). CONCLUSIONS: We suggest a role for combined polymorphisms in CARD8 and NALP3 in the development of CD in men, with obvious sex differences in the genetic susceptibility pattern. These findings give further support to the importance of innate immune responses in CD.