Ambient Air Pollution and Risk of Enterotomy, Gastrointestinal Cancer, and All-Cause Mortality among 4,708 Individuals with Inflammatory Bowel Disease: A Prospective Cohort Study

PPARγ/NF-κB axis contributes to cold-induced resolution of experimental colitis and preservation of intestinal barrier

BACKGROUND

Environmental stress is a significant contributor to the development of inflammatory bowel disease (IBD). The involvement of temperature stimulation in the development of IBD remains uncertain. Our preliminary statistical data suggest that the prevalence of IBD is slightly lower in colder regions compared to non-cold regions. The observation indicates that temperature changes may play a key role in the occurrence and progression of IBD. Here, we hypothesized that cold stress has a protective effect on IBD.

METHODS

The cold exposure model for mice was placed in a constant temperature and humidity chamber, maintained at a temperature of 4 °C. Colitis models were induced in the mice using TNBS or DSS. To promote the detection methods more clinically, fluorescence confocal endoscopy was used to observe the mucosal microcirculation status of the colon in the live model. Changes in the colonic wall of the mice were detected using 9.4 T Magnetic Resonance Imaging (MRI) imaging and in vivo fluorescence imaging. Hematoxylin and eosin (H&E) and Immunofluorescence (IF) staining confirmed the pathological alterations in the colons of sacrificed mice. Molecular changes at the protein level were assessed through Western blotting and Enzyme-Linked Immunosorbent Assay (ELISA) assays. RNA sequencing (RNA-seq) and metabolomics (n = 18) were jointly analyzed to investigate the biological changes in the colon of mice treated by cold exposure.

RESULTS

Cold exposure decreased the pathologic and disease activity index scores in a mouse model. Endomicroscopy revealed that cold exposure preserved colonic mucosal microcirculation, and 9.4 T MRI imaging revealed alleviation of intestinal wall thickness. In addition, the expression of the TLR4 and PP65 proteins was downregulated and epithelial cell junctions were strengthened after cold exposure. Intriguingly, we found that cold exposure reversed the decrease in ZO-1 and occludin protein levels in dextran sulfate sodium (DSS)- and trinitrobenzenesulfonic acid-induced colitis mouse models. Multi-omics analysis revealed the biological landscape of DSS-induced colitis under cold exposure and identified that the peroxisome proliferator-activated receptor (PPAR) signaling pathway mediates the effects of cold on colitis. Subsequent administration of rosiglitazone (PPAR agonist) enhanced the protective effect of cold exposure on colitis, whereas GW9662 (PPAR antagonist) administration mitigated these protective effects. Overall, cold exposure ameliorated the progression of mouse colitis through the PPARγ/NF-κB signaling axis and preserved the intestinal mucosal barrier.

CONCLUSION

Our study provides a mechanistic link between intestinal inflammation and cold exposure, providing a theoretical framework for understanding the differences in the prevalence of IBD between the colder regions and non-cold regions, and offering new insights into IBD therapy.

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

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

Associations of occupational exposure to micro-LiNiCoMnO2 particles with systemic inflammation and cardiac dysfunction in cathode material production for lithium batteries

Micro-LiNiCoMnO2 (MNCM), a cathode material with highest market share, has increasing demand with the growth of lithium battery industry. However, whether MNCM exposure brings adverse effects to workers remains unclear. This study aimed to explore the association between MNCM exposure with systemic inflammation and cardiac function. A cross-sectional study of 347 workers was undertaken from the MNCM production industry in Guangdong province, China in 2020. Metals in urine were measured using ICP-MS. The associations between metals, systemic inflammation, and cardiac function were appraised using a linear or logistic regression model. Bayesian kernel machine regression (BKMR) and generalized weighted quantile sum (gWQS) models were used to explore mixed metal exposures. The analysis of interaction and mediation was adopted to assess the role of inflammation in the relation between urinary metals and cardiac function. We observed that the levels of lithium (Li) and cobalt (Co) were positively associated with systemic inflammation and heart rate. The amount of Co contributed the highest weight on the increased systemic immune-inflammation index (SII) (59.8%), the system inflammation response index (SIRI) (44.3%), and heart rate (65.0%). Based on the mediation analysis, we estimated that SII mediated 32.3% and 20.9% of the associations between Li and Co with heart rate, and SIRI mediated 44.6% and 22.2% of the associations between Li and Co with heart rate, respectively. This study demonstrated for the first time that MNCM exposure increased the risk of workers' systemic inflammation and elevated heart rate, which were contributed by the excessive Li and Co exposure. Additionally, it indicates that systemic inflammation was a major mediator of the associations of Li and Co with cardiac function in MNCM production workers.

Circulating 25-hydroxyvitamin D concentration can predict bowel resection risk among individuals with inflammatory bowel disease in a longitudinal cohort with 13 years of follow-up

BACKGROUND

Although the beneficial properties of vitamin D in anti-inflammation and immunity-modulation are promising in the management of inflammatory bowel disease (IBD), data were limited for the critical IBD prognosis. The association between serum vitamin D levels and the risk of bowel resection in individuals with IBD remains largely unknown.

MATERIALS AND METHODS

The authors performed a longitudinal cohort study among 5474 individuals with IBD in the UK Biobank. Serum 25-hydroxyvitamin D [25(OH)D] was measured using direct competitive chemiluminescent immunoassay. Bowel resection events were ascertained via national inpatient data. Multivariable-adjusted Cox proportional hazard regression was used to examine the association between serum 25(OH)D and bowel resection risk, presented with hazard ratios (HRs) and 95% CIs. Restricted cubic spline (RCS) was used to evaluate dose-response associations.

RESULTS

During a mean follow-up of 13.1 years, the authors documented 513 incident bowel resection cases. Compared to participants with vitamin D deficiency, nondeficient participants showed a significantly reduced bowel resection risk in IBD (HR 0.72, 95% CI: 0.59-0.87, P =0.001), Crohn's disease (CD, HR 0.74, 95% CI: 0.56-0.98, P =0.038), and ulcerative colitis (UC, HR 0.73, 95% CI: 0.57-0.95, P =0.020). When comparing extreme quintiles of 25(OH)D level, participants with IBD showed a 34% reduced risk of bowel resection (95% CI: 11-51%, P =0.007) and participants with UC showed a 46% reduced risk (95% CI: 19-64%, P =0.003), while this association was not significant in CD (HR 0.93, 95% CI: 0.59-1.45, P =0.740). Linear dose-response associations were observed using the RCS curve (all P -nonlinearity>0.05).

CONCLUSION

Increased serum level of 25(OH)D is independently associated with reduced bowel resection risk in IBD. This association was significant in UC but may not be stable in CD. Vitamin D deficiency is a risk factor for bowel resection in individuals with IBD, and may be an effective metric in predicting and risk-screening surgical events.

Chronic PM2.5 exposure disrupts intestinal barrier integrity via microbial dysbiosis-triggered TLR2/5-MyD88-NLRP3 inflammasome activation

BACKGROUND

PM2.5, a known public health risk, is increasingly linked to intestinal disorders, however, the mechanisms of its impact are not fully understood.

PURPOSE

This study aimed to explore the impact of chronic PM2.5 exposure on intestinal barrier integrity and to uncover the underlying molecular mechanisms.

METHODS

C57BL/6 J mice were exposed to either concentrated ambient PM2.5 (CPM) or filtered air (FA) for six months to simulate urban pollution conditions. We evaluated intestinal barrier damage, microbial shifts, and metabolic changes through histopathology, metagenomics, and metabolomics. Analysis of the TLR signaling pathway was also conducted.

RESULTS

The mean concentration of PM2.5 in the CPM exposure chamber was consistently measured at 70.9 ± 26.8 μg/m³ throughout the study period. Our findings show that chronic CPM exposure significantly compromises intestinal barrier integrity, as indicated by reduced expression of the key tight junction proteins Occludin and Tjp1/Zo-1. Metagenomic sequencing revealed significant shifts in the microbial landscape, identifying 35 differentially abundant species. Notably, there was an increase in pro-inflammatory nongastric Helicobacter species and a decrease in beneficial bacteria, such as Lactobacillus intestinalis, Lactobacillus sp. ASF360, and Eubacterium rectale. Metabolomic analysis further identified 26 significantly altered metabolites commonly associated with intestinal diseases. A strong correlation between altered bacterial species and metabolites was also observed. For example, 4 Helicobacter species all showed positive correlations with 13 metabolites, including Lactate, Bile acids, Pyruvate and Glutamate. Additionally, increased expression levels of TLR2, TLR5, Myd88, and NLRP3 proteins were noted, and their expression patterns showed a strong correlation, suggesting a possible involvement of the TLR2/5-MyD88-NLRP3 signaling pathway.

CONCLUSIONS

Chronic CPM exposure induces intestinal barrier dysfunction, microbial dysbiosis, metabolic imbalance, and activation of the TLR2/5-MyD88-NLRP3 inflammasome. These findings highlight the urgent need for intervention strategies to mitigate the detrimental effects of air pollution on intestinal health and identify potential therapeutic targets.

Higher Dietary Quercetin Intake Is Associated with Lower Risk of Adverse Outcomes among Individuals with Inflammatory Bowel Disease in a Prospective Cohort Study

BACKGROUND

Cumulative preclinical evidence reported quercetin, a major flavonoid, can attenuate the disease activity of inflammatory bowel diseases (IBD). However, there is limited evidence that supports the benefits of quercetin for patients with IBD.

OBJECTIVES

To investigate whether dietary quercetin intake is associated with adverse outcomes among individuals with IBD in a prospective cohort study.

METHODS

We included 2293 participants with IBD (764 Crohn's disease [CD] and 1529 ulcerative colitis [UC]) from the UK Biobank. Dietary information was collected using validated 24-h dietary assessments, and quercetin intake was estimated based on national nutrient databases. Two outcomes, enterotomy and all-cause mortality, were obtained based on the national data. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

After a mean (standard deviation) follow-up of 9.6 (1.8) y, we documented 193 enterotomy events and 176 deaths. Compared with participants with the lowest quartile intake of quercetin, those in the highest quartiles were associated with lower risk of enterotomy (HR: 0.46; 95% CI: 0.28, 0.76) and all-cause mortality (HR: 0.53; 95% CI: 0.33, 0.83) in IBD. The inverse associations between quercetin and enterotomy were consistent in CD (HR: 0.30; 95% CI: 0.12, 0.78) but not UC (HR: 0.58; 95% CI: 0.32, 1.07), while the inverse associations between quercetin and mortality were consistent both in CD (HR: 0.37; 95% CI: 0.15, 0.92) and UC (HR: 0.55; 95% CI: 0.31, 0.95).

CONCLUSIONS

Higher dietary intake of quercetin was associated with lower risk of enterotomy and all-cause mortality in IBD. Our study provides novel evidence that further suggests the benefits of quercetin for patients with IBD, while also calling for further validation in other cohorts and clinical trials.

Causal association between air pollution and autoimmune diseases: a two-sample Mendelian randomization study

Background

In recent years, an increasing number of observational studies have reported the impact of air pollution on autoimmune diseases (ADs). However, no Mendelian randomization (MR) studies have been conducted to investigate the causal relationships. To enhance our understanding of causality, we examined the causal relationships between particulate matter (PM) and nitrogen oxides (NOx) and ADs.

Methods

We utilized genome-wide association study (GWAS) data on PM and NOx from the UK Biobank in European and East Asian populations. We also extracted integrated GWAS data from the Finnish consortium and the Japanese Biobank for two-sample MR analysis. We employed inverse variance weighted (IVW) analysis to assess the causal relationship between PM and NOx exposure and ADs. Additionally, we conducted supplementary analyses using four methods, including IVW (fixed effects), weighted median, weighted mode, and simple mode, to further investigate this relationship.

Results

In the European population, the results of MR analysis suggested a statistically significant association between PM2.5 and psoriasis only (OR = 3.86; 95% CI: 1.89-7.88; PIVW < 0.00625), while a potential association exists between PM2.5-10 and vitiligo (OR = 7.42; 95% CI: 1.02-53.94; PIVW < 0.05), as well as between PM2.5 and systemic lupus erythematosus (OR = 68.17; 95% CI: 2.17-2.1e+03; PIVW < 0.05). In East Asian populations, no causal relationship was found between air pollutants and the risk of systemic lupus erythematosus and rheumatoid arthritis (PIVW > 0.025). There was no pleiotropy in the results.

Conclusion

Our results suggest a causal association between PM2.5 and psoriasis in European populations. With the help of air pollution prevention and control, the harmful progression of psoriasis may be slowed.

Challenges of developing a green gastroenterology evidence base and how trainee research networks can fill the gaps

Trainee research networks are a collaborative effort to enable high-quality multicentre audits or research that is more widely accessible to trainees. Such networks lead, design and deliver research at a far higher scale than could be achieved locally and are carried out solely by trainees. There is an increasing focus on delivering research that is not only environmentally sustainable but also focuses on areas that can reduce the carbon footprint of service provision in gastroenterology and hepatology. In this manuscript, we performed a scoping review to understand the current evidence base of the impact of gastroenterology and hepatology services on the environment as well as exploring any association between pollution and climate change with gastrointestinal and liver disease. We further discuss the barriers that researchers face in delivering environmentally sustainable research, the limitation in clinical guidelines related to practicing environmentally sustainable gastroenterology and hepatology and how the trainee research networks are ideally placed to initiate change by developing, disseminating and implementing best practice in ‘green Gastroenterology’.

Editorial: Unravelling the fibres-low dietary fibre may lower risk of developing IBD. Authors' reply

This article is linked to Deng et al papers. To view these articles, visit https://doi.org/10.1111/apt.17649 and https://doi.org/10.1111/apt.17663