Intestinal Barrier in Post-Campylobacter jejuni Irritable Bowel Syndrome

Background: Campylobacter jejuni (C. jejuni) is one of the most common causes of bacterial gastroenteritis worldwide. One sequela of this infection is the development of post-infectious irritable bowel syndrome (PI-IBS). It has been suggested that a dysfunctional intestinal barrier may promote IBS development. We aimed to test this hypothesis against the background of the leaky gut concept for low-grade inflammation in PI-IBS. Methods: We identified patients with persistent PI-IBS symptoms after C. jejuni infection. During sigmoidoscopy, forceps biopsies were obtained for electrophysiological measurements of epithelial transport and barrier function in miniaturized Ussing devices. C. jejuni absence was checked by PCR and cytokine production with immunohistochemistry. Results: In PI-IBS, the epithelial resistance of the colon epithelium was unaltered, reflecting an intact paracellular pathway. In contrast, temperature-dependent horseradish peroxidase (HRP, 44 kDa) permeation increased. Short-circuit current (Isc) reflecting active anion secretion and ENaC-dependent electrogenic sodium absorption was unaffected. Early endosome antigen-1 (EEA1) and IL-4 levels increased. C. jejuni is not incorporated into the resident microbiota of the colon mucosa in PI-IBS. Conclusions: In PI-IBS after C. jejuni infection, macromolecule uptake via endocytosis was enhanced, leading to low-grade inflammation with pro-inflammatory cytokine release. The findings will allow C. jejuni-induced pathomechanisms to be targeted during infection and, thereafter to reduce sequelae such as PI-IBS

Epithelial barrier function of the colon in mixed type-irritable bowel syndrome

Einleitung Das Reizdarmsyndrom ist eine häufige Erkrankung, unter der fast jeder zweite Patient mit gastrointestinaler Symptomatik leidet. Die Patienten leiden unter Stuhlgangsveränderungen (Diarrhö und/oder Obstipation) und abdominellen Beschwerden (diffuse Schmerzen, Meteorismus). Bei Patienten mit Reizdarmsyndrom (RDS) scheint eine verstärkte motorische Darmaktivität und eine viszerale Hypersensitivität eine Rolle in der Pathogenese zu spielen. Ziel der vorliegenden Arbeit war die Erforschung weiterer pathophysiologischer Mechanismen der Diarrhö bzw. Verstopfungsmechanismen beim Reizdarmsyndrom vom Mischtyp (RDS-M). Methoden Es wurden Sigmabiopsien von Patienten mit Reizdarmsyndrom entnommen und in Ussing-Kammern elektrophysiologisch untersucht, um die Transport- und Barriereeigenschaften des Kolons funktionell zu charakterisieren. Auch war die Erforschung der Aktivität des epithelialen Natriumkanals (EnaC) wichtig, da eine Störung des EnaC als Diarrhö-Mechanismus bei chronisch entzündlichen Erkrankungen beschrieben wurde. Zudem wurde die Permeabilität des Darmgewebes gegenüber kleinen Makromolekülen untersucht. Mittels Western Blotting erfolgte die Expressionsanalyse von Tight Junction-Proteinen sowie die Darstellung der subzellulären Lokalisation dieser Proteine mit Hilfe der konfokalen Laser-Scanning-Mikroskopie. Für ein besseres Verständnis der Pathophysiologie wurde zuletzt mit Hilfe von Next Generation Sequencing die Analyse relevanter Genexpressionsmuster und Signalkaskaden durchgeführt. Ergebnisse Bei RDS-M-Patienten zeigte sich eine Tendenz zur Abnahme des epithe-lialen Widerstands (allerdings nicht statistisch signifikant). Bei Patienten mit RDS-M war die parazelluläre Permeabilität für Fluorescein und FITC-Dextran 4000 im Vergleich zur Kontrollgruppe erhöht. Dies weist auf strukturelle Veränderungen der parazellulären Durchlässigkeit des Epithels hin, die durch eine veränderte Expression von Tight Junction Proteinen erklärt werden kann. Tatsächlich zeigte die Western-Blot-Analyse eine Abnahme der Proteinexpression von Occludin, während andere Tight Junction-Proteine wie Claudine in ihrem Expressionslevel nicht signifikant verändert waren. Bei reduzierter Occludin-Expression im Western Blot und erhöhtem Flux für 4 kDa-FITC-Dextran und Fluorescein bot sich auch eine andere Erklärung an, nämlich eine veränderte Lokalisation von Tricellulin im Darmepithel, die durch Occludin gesteuert wird. In der Tat zeigte sich dann auch in der Folge, dass in der RDS-M-Gruppe eine geringere Co-Lokalisierung des Tricellulin-Signals mit ZO-1 in der trizellulären Tight Junction im Vergleich zu den Kontrollen vorlag und somit eine Heraussortierung von Tricellulin aus der trizellulären Tight Junction angenommen werden konnte. Schlussfolgerungen Die vorliegende Arbeit zeigt erstmalig, dass eine verminderte Expression von Occludin zu einer Umverteilung von Tricellulin aus der trizellulären Tight Junction heraus führt, die dann in einer erhöhten Makromolekülpermeabilität resultiert. Dies könnte einen wichtigen Pathomechanismus für das Reizdarmsyndrom vom gemischten Typ (RDS-M) darstellen, der zu einem Antigeneinstrom mit Entzündungsreaktionen in der Darmschleimhaut führen kann, die entlang des Leaky Gut-Konzepts pathophysiologisch zur Permission der Erkrankung beiträgt.Introduction Irritable bowel syndrome is a very common disease, affecting almost every second patient with gastrointestinal symptoms. Patients mainly suffer from bowel changes (diarrhea and/or constipation) and abdominal discomfort (diffuse pain, meteorism). In patients with irritable bowel syndrome (IBS), increased intestinal activity and visceral hypersensitivity appear to play a role in the pathogenesis. The aim of the present work was to explore further pathophysiological mechanisms of diarrhea or constipation in mixed-type irritable bowel syndrome (IBS-M). Methods To perform the study, sigmoid biopsies were obtained from patients with IBS and were electrophysiologically studied in Ussing chambers to functionally characterize the transport and barrier properties of the colon. Also, exploration of epithelial sodium channel (EnaC) activity was important, as disruption of EnaC has been described as a diarrhea mechanism in chronic inflammatory diseases. In addition, the permeability of intestinal tissue to small macromolecules was investigated. Western blot was used to analyze the expression of tight junction proteins and to visualize the subcellular localization of these proteins by confocal microscopy. Lastly, for a better understanding of the pathophysiology, analysis of relevant gene expression patterns and signaling cascades was performed using next generation sequencing. Results In IBS-M patients, there was a tendency for the epithelial resistance to be decreased, which did not reach statistical significance. Subepithelial resistance was not altered, suggesting the absence of subepithelial changes such as inflammation. In patients with IBS-M, the permeability of fluorescein and FITC-dextran was increased compared with the control group. Such an increased paracellular permeability indicates structural changes in the tight junction and may be explained by altered tight junction protein expression. Indeed, Western blot analysis showed a decrease in protein expression of occludin, whereas other claudins were not significantly altered. With reduced occludin expression in the Western blot and increased flux for 4 kDa FITC-dextran and fluorescein, we also considered an altered localization of tricellulin. In the IBS-M group, there was less co-localization of tricellulin with ZO-1 in the tricellular tight junction compared with controls indicating a redistribution of tricellulin off the tricellular tight junction. Conclusions The present work shows that decreased expression of occludin in IBS-M leads to a redistribution of tricellulin, which then results in increased macromolecular permeability. This may represent an important pathomechanism for IBS-M that leads to antigen influx with inflammatory responses in the intestinal mucosa, which pathophysiologically contributes to the permission of the disease along the leaky gut concept

Impaired Intestinal Permeability of Tricellular Tight Junctions in Patients with Irritable Bowel Syndrome with Mixed Bowel Habits (IBS-M)

Background: The underlying pathophysiology of irritable bowel syndrome (IBS) is still unclear. Our aim was to investigate the pathophysiological mechanisms of diarrhea, constipation, and antigen uptake in mixed-type IBS (IBS-M). Methods: Colonoscopic biopsies were obtained from IBS-M patients. Epithelial transport and barrier function of colonic mucosae were characterized in Ussing chambers using impedance spectroscopy. Mucosal permeability to macromolecules was measured. Western blotting for tight junction (TJ) proteins was performed and their subcellular localization was visualized by confocal microscopy. RNA-sequencing was performed for gene expression and signaling pathway analysis. Results: In IBS-M, epithelial resistance and ENaC-dependent sodium absorption were unchanged, while short-circuit current reflecting chloride secretion was reduced. Concomitantly, epithelial permeability for fluorescein and FITC-dextran-4000 increased. TJ protein expression of occludin decreased, whereas claudins were unaltered. Confocal microscopy revealed the de-localization of tricellulin from tricellular TJs. Involved pathways were detected as proinflammatory cytokine pathways, LPS, PGE2, NGF, and vitamin D. Conclusions: Decreased anion secretion explains constipation in IBS-M, while ion permeability and sodium absorption were unaltered. Reduced occludin expression resulted in the delocalization of tricellulin from the tricellular TJ, leading to increased macromolecular permeability that contributes to antigen influx into the mucosa and perpetuates a low-grade inflammatory process

Epithelial barrier dysfunction in lymphocytic colitis through cytokine-dependent internalization of claudin-5 and-8

Background Watery diarrhea is the cardinal symptom of lymphocytic colitis (LC). We have previously shown that colonic Na malabsorption is one of the major pathologic alterations of LC and found evidence for an epithelial barrier defect. On these grounds, this study aimed to identify the inherent mechanisms of this epithelial barrier dysfunction and its regulatory features. Methods Epithelial resistance (R-epi) was determined by one-path impedance spectroscopy and H-3-mannitol fluxes were performed on biopsies from sigmoid colon in miniaturized Ussing chambers. Tight junction proteins were analyzed by Western blot and confocal microscopy. Inflammatory signaling was characterized in HT-29/B6 cells. Apoptosis and mucosal surface parameters were quantified morphologically. Results Repi was reduced to 53% and H-3-mannitol fluxes increased 1.7-fold in LC due to lower expression of claudin-4, -5, and -8 and altered subcellular claudin-5 and -8 distributions off the tight junction. TNF alpha and IFN gamma could mimic subcellular redistribution in HT-29/B6 cells, a process which was independent on MLCK activation. Epithelial apoptosis did not contribute to barrier dysfunction in LC and mucosal surface area was unchanged. Conclusions Epithelial barrier dysfunction in LC occurs through downregulation of claudin-4, -5, and -8, and redistribution of claudin-5 and -8 off the tight junction, which contributes to diarrhea by a leak-flux mechanism. The key effector cytokines TNF alpha and IFNc gamma turned out to be the trigger for redistribution of claudin-5 and -8. Thus, alongside sodium malabsorption, leak-flux is yet another important diarrheal mechanism in LC

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care

Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021

BackgroundFuture trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050.MethodsUsing forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline.FindingsIn the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8–63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0–45·0] in 2050) and south Asia (31·7% [29·2–34·1] to 15·5% [13·7–17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4–40·3) to 41·1% (33·9–48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6–25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5–43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5–17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7–11·3) in the high-income super-region to 23·9% (20·7–27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5–6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2–26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [–0·6 to 3·6]).InterpretationGlobally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions.FundingBill & Melinda Gates Foundation.</p

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally