Air pollution effects on the gut microbiota: a link between exposure and inflammatory disease

Mediation role of gut microbiota in the association between ambient fine particulate matter components and cardiovascular disease: Evidence from a China cohort

BACKGROUND

Pairwise associations among fine particulate matter (PM2.5), gut microbiota, and cardiovascular disease (CVD) have been established. However, the mediating role of gut microbiota in the relationship between PM2.5 and its components and CVD remains unclear.

METHODS

We included 1459 participants from the China Multi-Ethnic Cohort between May 2018 and September 2019. CVD was identified using ICD-10 codes based on hospital surveillance system. PM2.5 and its components were sourced from the ChinaHighAirPollutants dataset. Gut microbiota was obtained from 16S rRNA sequencing of stool samples, and five α-indexes along with 1088 gut compositions were used as mediators. Cox proportional hazards and multiple linear regression were used to explore the associations among PM2.5 and its components, gut microbiota, and CVD. Causal mediation analysis was conducted to evaluate the potential mediating role of gut microbiota between PM2.5 and its components and CVD.

RESULTS

Among all the participants, 204 (14.0 %) had developed CVD during a 5501 person-year follow-up (median, 3.8 years). The ACE, Chao1, and Obs indexes positively mediated the associations of PM2.5 and its components with both CVD and stroke, with mediation proportions ranging from 7.9 % to 8.9 % for CVD and 10.0 %-12.1 % for stroke. The ACE index had the highest mediation proportion (12.1 %) in the relationship between sulfate and stroke. The genus Pasteurella also demonstrated a mediating role, accounting for 2.6 %-3.2 % for CVD, and 2.5 %-3.6 % for stroke, exhibiting the highest mediation proportion (3.6 %) on the association between black carbon or nitrate and stroke.

CONCLUSION

Three α-indexes (ACE, Chao1, and Obs) and the Pasteurella positively mediated the association between PM2.5 and its components and CVD risk. Enhancing the richness of gut microbiota could potentially reduce the risk of CVD induced by PM2.5 and its components.

Early-life and concurrent predictors of the healthy adolescent microbiome in a cohort study

BACKGROUND

The microbiome of adolescents is poorly understood, as are factors influencing its composition. We aimed to describe the healthy adolescent microbiome and identify early-life and concurrent predictors of its composition.

METHODS

We performed metagenomic sequencing of 247 fecal specimens from 167 adolescents aged 11-14 years participating in the Health Outcomes and Measures of the Environment (HOME) Study, a longitudinal pregnancy and birth cohort (Cincinnati, OH). We described common features of the adolescent gut microbiome and applied self-organizing maps (SOMs)-a machine-learning approach-to identify distinct microbial profiles (n = 4). Using prospectively collected data on sociodemographic characteristics, lifestyle, diet, and sexual maturation, we identified early-life and concurrent factors associated with microbial diversity and phylum relative abundance with linear regression models and composition with Kruskal-Wallis and Fisher's exact tests.

RESULTS

We found that household income and other sociodemographic factors were consistent predictors of the microbiome, with higher income associated with lower diversity and differential relative abundances of Firmicutes (increased) and Actinobacteria (decreased). Sexual maturation, distinct from chronological age, was related to higher diversity in females and differences in phylum relative abundances and compositional profiles in both males and females.

CONCLUSIONS

Our study suggests that adolescence is a unique window for gut microbial composition and that it may be shaped by both early-life and concurrent exposures, highlighting its potential in future epidemiologic research.

Sex differences in the association between long-term ambient particulate air pollution and the intestinal microbiome composition of children

The intestinal microbiome is essential for gastrointestinal and overall health, yet its response to air pollution in children remains underexplored. In a study involving 412 young children from the ENVIRONAGE cohort, stool samples were analysed via Illumina Miseq sequencing to assess microbiome alpha diversity (observed richness, species evenness, and Shannon diversity) and composition. Exposure to previous year particulate air pollution (black carbon, PM2.5, coarse PM, and PM10) was modeled using high-resolution spatial-temporal interpolation models. Multiple linear regression models were adjusted for a priori selected covariables and stratified by sex. Furthermore, we performed a differential relative abundance analysis at family and genus level, while accounting for the same covariables. Statistically significant effect modification by sex was apparent for several intestinal alpha diversity indices and air pollutants. In boys, we observed negative associations between particulate air pollution exposure and intestinal microbiome richness (estimates ranging from -5.55 to -9.06 per interquartile range (IQR) increase in particulate air pollution exposure) and Shannon diversity (estimates ranging from -0.058 to -0.095 per IQR increase). Differently, in girls non-significant positive associations were observed with species evenness (estimates ranging from 0.019 to 0.020 per IQR increase) and Shannon diversity (estimate 0.065 per IQR increase in black carbon). After multiple testing correction, we reported several bacterial families and genera (Streptococcaceae, Clostridiales Incertae Sedis XIII, Coriobacteriaceae, Streptococcus, and Paraprevotella) to be oppositely associated with particulate air pollution exposure in boys and girls. Our findings show a sex-dependent association between particulate air pollution exposure and intestinal microbiome composition, highlighting boys as potentially more vulnerable to diversity loss associated with childhood exposure to particulate pollution.

Relationship between long-term exposure to fine particulate air pollution and colorectal cancer mortality in Taiwan

The International Agency for Research on Cancer classified fine particulate matter (PM2.5) air pollution as carcinogenic to humans (Group I). Although PM2.5 exposure has been associated with lung cancer occurrence, few studies investigated this association with non-lung cancer. Colorectal cancer (CRC) is the third leading cause of cancer deaths both among men and women. In Taiwan, deaths attributed to CRC vary considerably across townships, suggesting involvement of the environment. The aim of this study was to examine the association between long-term ambient PM2.5 exposure and deaths attributed to CRC in 66 municipal areas across Taiwan. Annual PM2.5 levels were compared against age-standardized CRC mortality rates in male and female residents of these municipalities from 2012 to 2021. Annual PM2.5 levels of different municipalities were sub-divided into tertiles. Adjusted risk ratio (RR) was calculated by multiple regression analyses, controlling for municipal lung cancer deaths, urbanization level, annual average household income, and density of physicians in the municipal areas. For males, adjusted RRs for CRC death were 1.1 (95% CI = 1.05-1.15) for municipalities with PM2.5 levels ranging from 18.96 to 25.19 µg/m3and 1.15 (95% CI = 1.1-1.21) for levels ranging from 25.2 to 29.48 µg/m3, respectively, compared to those areas belonging to the lowest tertiles. Our analysis of trend suggested that risk of CRC-related death paralleled increases PM2.5 levels in males. For females, adjusted RRs were 1.18 (95% CI = 1.12-1.25) and 1.12 (95% CI = 1.06-1.19), respectively. Evidence indicated that long-term exposure to PM2.5 may elevate the risk of CRC-related death in both men and women in Taiwan.

Effects of Climate Change on the Immune System: A Narrative Review

Background and Aims

Human activities have greatly influenced global temperatures, leading to climate change and global warming. This narrative review aims to explore the relationship between climate change and the immune system, focusing on how environmental stressors can affect immune regulation, leading to both hyperactivity and suppression.

Methods

A comprehensive search was conducted in PubMed and Google Scholar for peer-reviewed studies published up to June 2024. The search terms included "climate change," "human health," "infection," "immunity," and "disease." Inclusion criteria were based on relevance, originality, and accessibility.

Results

Exposure to elevated temperatures can significantly impair immune system cells, leading to an overproduction of signaling molecules that promote inflammation. Temperature fluctuations have been shown to influence various aspects of the adaptive immune response, including immune cell mobilization, antigen processing and presentation, lymphocyte trafficking and activation, and the functionality of B and T cells. Notably, some research suggests that heat stress negatively impacts B lymphocyte differentiation, replication, and proportion, resulting in decreased immunoglobulin and cytokine production, and contributing to immunosuppression. Additionally, climate change-related exposures can compromise epithelial barriers in the skin, lungs, and gut, leading to microbial dysbiosis, and immune dysregulation. Furthermore, environmental factors such as temperature variations, humidity, and air pollutant levels may exacerbate the prevalence of infectious diseases, including measles and HIV, with varying impacts on acute, chronic, and latent infections, further contributing to immune variability.

Conclusion

Climate change, particularly increased temperatures, significantly impacts immune system function, leading to both heightened inflammatory responses, and immunosuppression. Future research should focus on developing comprehensive and sustainable management strategies to enhance health resilience in the face of ongoing climatic changes.

Effects of urban airborne particulate matter exposure on the human upper respiratory tract microbiome: a systematic review

Exposure to air pollutants has a direct impact on human health, resulting in increased mortality rates. Airborne particulate matter (PM) has major adverse effects on health and can be classified as high-risk respiratory particles (fine/PM2.5, aerodynamic diameter < 2.5 µm) or thoracic particles (coarse/PM10, aerodynamic diameter < 10 µm). In addition, airborne PM can carry microbial communities that alter the commensal microbiota and lead to dysbiosis. Our aim was to synthesize the current research evidence describing the association between air pollution exposure and the microbiome composition of the upper respiratory tract (URT) of the adult population. In this work, a systematic search of the PubMed, EMBASE and Scopus databases was conducted. A total of 9 studies published from 2018 to 2023 were included. 66.5% of the participants were exposed to PM2.5 concentrations higher than 40 µg/m3, and data showed that PM2.5 atmospheric levels were positively correlated with PM10 (rs = 0.95, p < 0.001). All the reviewed studies performed 16S rRNA sequencing of the V3-V4 region from URT samples, using different methods. Overall, evidence of URT microbiome alterations after high PM exposure was observed, with seasonal and geographical influence. Discordant findings were found about bacterial diversity, with a predominant decrease after exposure to high PM levels. Regarding microbiome composition, the relative abundance of the Actinobacteria phylum declined following exposure to high levels of PM, but that of Bacteroidetes and Fusobacteria increased. The studies showed a low-middle risk of bias due to heterogeneity regarding sample processing, sequencing methods, and confounder control. To confirm the observed evidence of an association between PM levels and alterations in the URT microbiome, we strongly recommend that future research work be conducted in accordance with standard guidelines for reporting microbiome studies. In summary, the entry of fine and coarse particles into the URT is associated with microbial dysbiosis, increasing the risk of developing respiratory diseases and allergies.Prospero registration: This systematic review was registered on PROSPERO (#CRD42023416230).

A Low Dietary Quality Index in a Newly Diagnosed Inflammatory Bowel Disease Cohort: Results from a Case-Control Study

BACKGROUND

Epidemiological evidence suggests a link between the risk of IBD and diet. Macro- and micro- nutrient intake, diet quality and dietary patterns may play a pivotal role in disease pathogenesis. We aimed to study the dietary intake of newly diagnosed IBD patients compared to non-IBD controls.

METHODS

A cohort of newly diagnosed IBD patients were invited to complete the Scottish Collaborative Group Food Frequency Questionnaire (SCGFFQ) at their first clinic visit. Controls were recruited from non-IBD ambulatory patients, university students, and healthcare workers. The SCGFFQ estimates habitual diet over a 3-month period. Component nutrient data were calculated based on previous validation studies, deriving nutrient data by comparison of the SCGFFQ to actual weighted food records. Data on age, gender, ethnicity, and disease phenotype were collected. The intake of macro- and micro-nutrients was expressed as mean and standard deviation and compared using the Kruskal-Wallis test. Dietary patterns were derived using principal component analysis. Differences in the dietary patterns for age, gender, and ethnicity were analysed by logistic regression analysis. The diet quality was compared to the dietary recommendation values (DRVs) and measured using the diet quality index.

RESULTS

We enrolled 160 IBD cases (114 UC and 46 CD) and 126 non-IBD controls, and in the study, with a median age across the groups of 40 years (IQR = 24) for UC, 34 years (IQR = 29) for CD, and 36 years (IQR = 24) for non-IBD controls. The diet quality indexes for both UC and CD were low compared to controls: 59.0% (SD 18.0) for UC, 46.0% (SD 17.7) for CD, and 63.2% (SD 17.1) controls. UC patients had excessive total energy consumption (>2500 kcal/day) compared to the DRVs. UC patients reported higher retinol, vitamin D, riboflavin, niacin, vitamin B6, vitamin B12, and panthanoic acid intake, consistent with a diet rich in animal products and low in fruit/vegetable intake. This is likely driven by higher consumption of dietary patterns 2 (rich in carbohydrates, refined sugar and low fibre) and 5 (refined sugar and saturated fat) in the UC cohort. Dietary pattern 1 (variety of food items and oily fish) was less likely to be consumed by the CD population. CD patients tended to have a lower overall intake of both macro- and micro-nutrients.

CONCLUSIONS

The dietary patterns identified here are a proof of concept, and the next phase of the study would be to ideally monitor these patterns in a case-control cohort prospectively, and to further understand the mechanisms behind which dietary patterns influence IBD. Patients with newly diagnosed CD have low dietary quality and lower overall intake of macro- and micro-nutrients. This finding supports the role for dietetic attention early in newly diagnosed CD.

Short-Term Exposure to Ambient Particulate Matter Pollution and Surgical Outcomes

INTRODUCTION

Particulate matter less than 2.5 μm in diameter (PM2.5) can activate inflammatory cascades, cause oxidative damage, and induce cell death. Short-term exposures to PM2.5 have been associated with appendicitis and inflammatory bowel disease presentations, yet it is unclear if exposures may impact surgical recovery.

METHODS

We conducted a retrospective cohort study of adult, colorectal surgery patients from 2006 to 2021. Institutional American College of Surgeons National Surgical Quality Improvement Program data were linked to Environmental Protection Agency PM2.5 concentrations on the day of admission stratified into low, moderately elevated, and high exposures. The environmental justice index chronic environmental burden and social vulnerability modules accounted for chronic stressors. The outcomes included length of stay (LOS), complications, and readmissions. After appropriate bivariate tests, multivariable regression models for the primary outcomes were constructed.

RESULTS

1038 patients were included with the majority experiencing low PM2.5 (53.4%, n = 554). Patients were similar in terms of demographic, clinical, and procedural characteristics across pollution groups, with a median age of 59.6, 53.5% female, 38.3% Black, and 74.5% American Society of Anesthesiologists class 3. The unadjusted outcomes did not differ significantly across groups; however, on adjusted models, higher PM2.5 groups had longer LOS: incident rate ratio 1.12 [95% CI 1.05-1.19] and incident rate ratio 1.37 [95% CI 1.16-1.62] for moderately elevated and high PM2.5, respectively (P < 0.001).

CONCLUSIONS

This study found a novel association between surgical outcomes and short-term ambient air pollution, with higher PM2.5 on the day of admission associated with longer LOS. Notably, this is also the first surgical study to use the environmental justice index to control for social and environmental determinants of health.

Psychological repercussions of PM air pollution in human aging: a comprehensive review of urban and rural environments

Air pollution and its effects on population health are currently among the most important public health issues. It is well established that the impact of air pollution on health is exceedingly high, although it ignores its real scope and effects on the aging process because studies on air quality have largely focused on younger age groups. Herein, we emphasize the relevance of air quality to the behavioral aging process, taking into account the place of residence - rural or urban. We raise the following question: Can air quality and residential settings modulate cognitive, emotional and social behaviors during the aging? Some studies have analyzed the role of residential settings and air pollution in the context of a behavioral frame in elderly people. Based on the analyzed literature, this revision concluded that air pollutants affect cognitive function, increasing the risk of dementia as well as depression and anxiety emotional responses. In addition, social networks and inclusion can modulate and mitigate the effects observed during the aging in rural areas that are exposed to less contamination. Although there is no consensus, it seems that some observed behavioral effects are sex-dependent, as women are more vulnerable to air pollution. Additionally, we examined why older adults are vulnerable to the health effects of Particulate Matter (PM) exposure and highlighted the importance of social health in this context. Environmental agents could be the key to understanding the susceptibility and variability observed during aging in behavioral symptoms. Although cognitive decline is related to increased age, it is not a manipulated factor. Efforts should be centered on locating factors implicated in the aging process that could be susceptible to manipulation or variation, such as the choice of the place of residence and the air that we are breathing. Given the significant societal impact of PM, research and policy regulations should be closely aligned and collaborative.

Particulate toxic elements' oxidative potential and gastrointestinal bioaccessibility features in the vicinities of coal-fired mineral processing industries, India

Particulate matter (PM) poses significant health risks due to its ability to generate reactive oxygen species (ROS) and transport toxic metal(loid)s into the human body. In this study, an in vitro physiologically based extraction test (PBET) method, allowing the simulation of the gastric phase (GPh) and intestinal phase (IPh) of human digestion, was applied to evaluate bioaccessibility of eleven potentially toxic elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in airborne particulate matter (APM) samples collected from an urban-residential area in Chhattisgarh, India. Additionally, oxidative potential (OP) was assessed using the dithiothreitol (DTT) assay for a comprehensive understanding of PM toxicity. The bioaccessibility of metal(loid)s varied significantly across phases, with gastric phase solubility upto ~ 75%, attributed to its lower pH enhancing metal dissolution. Elevated DTT responses were recorded for PM10 and PM2.5, driven primarily by Fe, Zn, and Pb, underlining their pivotal role in oxidative stress generation. Correlation analyses demonstrated strong associations between bioaccessible fractions and OP, especially in the GPh. The findings advance understanding by linking bioaccessibility with ROS generation and highlight the importance of particle size and solubility in assessing the health risks posed by PM. These insights provide a foundation for improved risk assessments and mitigation strategies targeting emissions from high-temperature processing industries, and vehicular activities, on a global scale.

The association between ambient air pollution and colorectal cancer: a Mendelian randomization study

Mounting epidemiology studies have reported the potential associations between ambient air pollution exposure and colorectal cancer (CRC). However, the genetic association between ambient air pollution and CRC remains unclear. Using the Genome-wide association study (GWAS) data from UK biobank, we explored the genetic association of CRC (5,657 cases and 372,016 controls) with four ambient air pollutants (PM2.5, PM10, NO2, NOx; n = 423,796 to 456,380) under the framework of Mendelian randomization (MR). Our results revealed a significant association between long-term NO2 exposure (per 10 µg/m3) and increased CRC risk, with an odds ratio (OR) of 1.02 (95% confidence interval [CI]: 1.00-1.03), while no statistical association was found between CRC risk and the other air pollutants. Sensitivity analysis confirmed the robustness of the results. It is imperative to consider the impact of air pollution, particularly NO2, in mitigating the risk of CRC.

Unraveling the mechanisms underlying air pollution-induced dysfunction of the oral-gut-brain axis: implications for human health and well-being

Air pollution exposure has become an international health issue that poses many risks to life and health. The bidirectional regulatory network, known as the oral-gut-brain axis connects the oral cavity, intestine, and central nervous system, as well as its influence on health outcomes from exposure to air pollution is receiving increased attention. This article systematically details the epidemiological evidence linking air pollutants to diseases affecting the oral, respiratory, intestinal, and nervous systems, while also explaining the route of air pollutants via the oral-gut-brain axis. The oral-gut-brain axis anomalies resulting from air pollution and their underlying molecular processes are also covered. The study provides a fresh viewpoint on how exposure to air pollution affects health and investigates cutting-edge preventative and therapeutic techniques.

Environmental exposures related to gut microbiota among children with asthma: a pioneer study in Taiwan

Gut microbiota plays a crucial role in human health and can be influenced by environmental factors. While past studies have examined the impact of the environment on gut microbiota, vulnerable populations have often been overlooked. This study aimed to investigate the association between environmental exposures, air pollution and greenspace, and gut microbiota in asthmatic children. Data were collected during the recovery period for 41 eligible children. Air pollution was estimated using an ensemble learning model that combined regression and machine-learning algorithms, while greenspace was quantified using the normalized difference vegetation index (NDVI) and green land-cover data. The lag effects of exposures were assessed within defined buffer zones surrounding each child's residence. A generalized additive model was applied to examine associations. Results revealed a marginally significant negative association between 1-day lag exposure to NO₂ and gut microbiota indices, such as observed bacteria (Coef.: -1.130; 95 %CI -2.287, 0.027) and bacterial richness (Coef.: -2.420; 95 %CI -4.987, 0.146). The 8-day lagged average exposure to PM2.5 and O₃ also showed negative impacts on bacterial diversity. In contrast, the 1-month lagged average exposure to greenspace was positively associated with microbiota indices. Air pollution and greenspace were also linked to specific bacterial abundances, such as Streptococcus. This study underscores the need for further research on how environmental factors may influence immunity in asthmatic children by altering gut microbiota.

The interaction between genetic predicted gut microbiome abundance and particulate matter on the risk of incident asthma in adults

Air pollution and gut microbial abundance (GMA) are both closely related with asthma incidence. This study aims to explore significant interact on the risk of incident asthma in adult exist between GMA and PM2.5 exposure based on a prospective cohort of UK Biobank. Polygenic score of GMA was calculated using 19 distinct single nucleotide polymorphisms. PM2.5 exposure was predicted using a validated Land Use Regression model. Incident asthma was identified by linking with medical encounters or first occurrence source. Cox proportional hazards regression models were used to evaluate the associations. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were calculated. During an average follow-up of 11.4 years within 390,054 participants, a total of 11,312 asthma cases occurred with an incidence density of 2.54 per 1000 person years. Participants with the highest PM2.5 and GMA exposure were associated with a 13 % (HR = 1.13, 95 % CI: 1.05, 1.22; Pfor trend < 0.001) higher and 16 % (HR = 0.84, 95 %CI: 0.74, 0.94; Pfor trend < 0.01) lower risk of incident asthma, respectively. A significant negative additive interaction between GMA and PM2.5 exposure with the risk of incident asthma in adult was found (Relative Excess Risk due to Interaction = -0.08, 95 % CI, -0.16, -0.002). Participants with very high GMA and lowest PM2.5 exposure level were associated with a 26 % (HR = 0.74, 95 % CI: 0.57, 0.96) lower risk of incident asthma. A higher level of GMA has the potential to alleviate the detrimental effect of PM2.5 exposure on the risk of asthma in adults. Strategies targeting GMA, such as modifying diet and using probiotics supplement may be helpful for preventing asthma derived from PM2.5 exposure.

Shaping oral and intestinal microbiota and the immune system during the first 1,000 days of life

The first 1, 000 days of life, from the fetal stage of a woman's pregnancy to 2 years of age after the baby is born, is a critical period for microbial colonization of the body and development of the immune system. The immune system and microbiota exhibit great plasticity at this stage and play a crucial role in subsequent development and future health. Two-way communication and interaction between immune system and microbiota is helpful to maintain human microecological balance and immune homeostasis. Currently, there is a growing interest in the important role of the microbiota in the newborn, and it is believed that the absence or dysbiosis of human commensal microbiota early in life can have lasting health consequences. Thus, this paper summarizes research advances in the establishment of the oral and intestinal microbiome and immune system in early life, emphasizing the substantial impact of microbiota diversity in the prenatal and early postnatal periods, and summarizes that maternal microbes, mode of delivery, feeding practices, antibiotics, probiotics, and the environment shape the oral and intestinal microbiota of infants in the first 1, 000 days of life and their association with the immune system.

Low-dose radiation ameliorates PM2.5-induced lung injury through non-canonical TLR1/TLR2-like receptor pathways modulated by Akkermansia muciniphila

Exposure of PM2.5 can cause different degrees of lung injury, which is referred with inflammatory response. Some evidences showed that low-dose radiation (LDR) induces hormesis in immune, however, it is unknown if LDR ameliorates the PM2.5-induced lung injury. Additionally, gut microbiota and inflammation are crucial in lung injury and the health benefits of LDR through gut microbiota need further exploration. Here, we aim to investigate the impact of LDR on PM2.5-induced lung injury in vivo and in vitro, and elucidated the potential mechanisms of anti-inflammation activated by gut microbiota. We observed that LDR ameliorated the lung damage induced by PM2.5 in mice. Additionally, after PM2.5 exposure, M1 polarization of macrophages in alveolar lavage fluid and Th1 polarization in spleen increased, pro-inflammatory cytokines (IL-1, IL-6 and TNF-α) increased and anti-inflammatory cytokines (IL-4, IL-10 and TGF-β) decreased in lung and serum. LDR could deteriorate the changes described as above. Intriguingly, Akkermansia muciniphila (Akk) differed most significantly in the gut microbiota of mice. Notably, PM2.5 activated the Toll-like receptors-induced MyD88/NF-κB pathways to mediate the pro-inflammation, and LDR could inhibited the pathway. However, the TLR1 and TLR2 continuously increased after LDR, indicating the downstream non-canonical TLR1/TLR2 pathway of Akk was activated to blunt the pro-inflammation of PM2.5. Our results strongly indicate that LDR-induced activation of gut Akk-dependent non-canonical TLR1/TLR2-like receptor pathway ameliorates lung injury and inflammation resulted from PM2.5.

DAMP-ing IBD: Extinguish the Fire and Prevent Smoldering

In inflammatory bowel diseases (IBD), the most promising therapies targeting cytokines or immune cell trafficking demonstrate around 40% efficacy. As IBD is a multifactorial inflammation of the intestinal tract, a single-target approach is unlikely to solve this problem, necessitating an alternative strategy that addresses its variability. One approach often overlooked by the pharmaceutically driven therapeutic options is to address the impact of environmental factors. This is somewhat surprising considering that IBD is increasingly viewed as a condition heavily influenced by such factors, including diet, stress, and environmental pollution-often referred to as the "Western lifestyle". In IBD, intestinal responses result from a complex interplay among the genetic background of the patient, molecules, cells, and the local inflammatory microenvironment where danger- and microbe-associated molecular patterns (D/MAMPs) provide an adjuvant-rich environment. Through activating DAMP receptors, this array of pro-inflammatory factors can stimulate, for example, the NLRP3 inflammasome-a major amplifier of the inflammatory response in IBD, and various immune cells via non-specific bystander activation of myeloid cells (e.g., macrophages) and lymphocytes (e.g., tissue-resident memory T cells). Current single-target biological treatment approaches can dampen the immune response, but without reducing exposure to environmental factors of IBD, e.g., by changing diet (reducing ultra-processed foods), the adjuvant-rich landscape is never resolved and continues to drive intestinal mucosal dysregulation. Thus, such treatment approaches are not enough to put out the inflammatory fire. The resultant smoldering, low-grade inflammation diminishes physiological resilience of the intestinal (micro)environment, perpetuating the state of chronic disease. Therefore, our hypothesis posits that successful interventions for IBD must address the complexity of the disease by simultaneously targeting all modifiable aspects: innate immunity cytokines and microbiota, adaptive immunity cells and cytokines, and factors that relate to the (micro)environment. Thus the disease can be comprehensively treated across the nano-, meso-, and microscales, rather than with a focus on single targets. A broader perspective on IBD treatment that also includes options to adapt the DAMPing (micro)environment is warranted.

Inhalation exposure to chemicals, microbiota dysbiosis and adverse effects on humans

As revealed by culture-independent methodologies, disruption of the normal lung microbiota (LM) configuration (LM dysbiosis) is a potential mediator of adverse effects from inhaled chemicals. LM, which consists of microbiota in the upper and lower respiratory tract, is influenced by various factors, including inter alia environmental exposures. LM dysbiosis has been associated with multiple respiratory pathologies such as asthma, lung cancer, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF). Chemically-induced LM dysbiosis appears to play significant roles in human respiratory diseases, as has been shown for some air pollutants, cigarette smoke and some inhalable chemical antibiotics. Lung microbiota are also linked with the central nervous system (CNS) in the so-called lung-brain axis. Inhaled chemicals that undergo mucociliary clearance may be linked to respiratory conditions through gut microbiota (GM) dysbiosis in the so-called Gut-Lung axis. However, current linkages of various disease states to LM appears to be associative, with causal linkages requiring further studies using more robust approaches, methods and techniques that are different from those applied in studies involving (GM). Most importantly, the sampling techniques determine the level of risk of cross contamination. Furthermore, the development of continuous or semi-continuous systems designed to replicate the lung microbiome will go a long way to further LM dysbiosis studies. These challenges notwithstanding, the preponderance of evidence points to the significant role of LM-mediated chemical toxicity in human disease and conditions.

Specifying the Associations between PM2.5 Constituents and Gastrointestinal Cancer Incidence: Findings from a Prospective Cohort Study in Beijing, China

This study aimed to test the association between PM2.5 and the incidence of gastrointestinal (GI) cancer, and further to detect the primary constituents on this association. A sum of 142,982 participants without GI cancer at baseline were derived from the National Urban Cancer Screening Program in Beijing (2013-2019). The 5 year averaged concentrations of PM2.5 mass and its five constituents, namely, black carbon (BC), ammonium (NH4+), nitrate (NO3-), organic matter (OM), and inorganic sulfate (SO42-), were estimated by using a hybrid machine learning model. The Cox proportional hazard model with fixed effects was used to explore the associations between PM2.5 mass and its constituents with the incidence of GI cancer. The double-exposure linear model, the mixture exposure model of quantile-based g-computation, and an explainable machine learning model were utilized to evaluate the importance of different PM2.5 constituents. Long-term exposure to PM2.5 mass and its constituents was linearly associated with GI cancer; the estimated hazard ratio and 95% confidence interval (95% CI) of per standard deviation increment were 1.367 (95% CI: 1.257 to 1.487) for PM2.5 mass, 1.434 (95% CI: 1.307 to 1.574) for BC, 1.255 (95% CI: 1.169 to 1.349) for NH4+, 1.217 (95% CI: 1.139 to 1.301) for NO3-, 1.410 (95% CI: 1.287 to 1.546) for OM, and 1.410 (95% CI: 1.288 to 1.542) for SO42-. By using multiple methods, results indicated that SO42- and BC were the most important constituents. Results indicated that long-term exposure to PM2.5 was associated with a high incidence of GI cancer, and BC and SO42- were robustly identified as the primary constituents.

Translocation of black carbon particles to human intestinal tissue

BACKGROUND

Evidence is accumulating that elevated levels of particulate air pollution, including black carbon, have been linked to gastrointestinal disorders and a lower intestinal bacterial richness and diversity. One of the hypothesized underlying mechanisms is the absorption of air pollution-related particles from the gastrointestinal tract.

METHODS

We visualized and quantified black carbon particles via white light generation under femtosecond-pulsed laser illumination in ileum and colon biopsies of five human patients. The biodistribution was assessed in three different layers (i.e., mucosa, submucosa, and muscularis propria).

FINDINGS

Black carbon particles could be identified in all three tissue layers of the ileum and colon biopsies of five participants (two men and three women; mean ± standard deviation age, 76.40 ± 7.37 years), and their carbonaceous nature was confirmed via emission fingerprinting. The median (±SD) black carbon load was borderline statistically significantly higher in the ileum compared to the colon (1.21 × 105 ± 1.68 × 104 particles/mm3 versus 9.34 × 104 ± 1.33 × 104 particles/mm3; p = 0.07) and was driven by a difference in black carbon load in the submucosa layer (p = 0.01). Regarding the three tissue layers, loads were higher in the submucosa, compared with the mucosa (ileum: +76%, p < 0.0001; colon: +70%, p = 0.0001) and muscularis propria (ileum: +88%, p < 0.0001; colon: +88%, p < 0.0001). In ileum, loads were borderline higher in the mucosa versus muscularis propria (p = 0.09).

INTERPRETATION

This explorative study provides real-life evidence that black carbon particles can reach the intestinal tissue and accumulate in different intestinal tissue layers. These findings support further research into how particulate air pollution directly affects gastrointestinal health.

FUNDING

Thessa Van Pee holds a doctoral fellowship from the Research Foundation Flanders (FWO), grant number: 11C7421N. Tim Nawrot is a Methusalem grant holder.

Association Between Chronic Pain and Fatigue Severity with Weather and Air Pollution Among Females with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Weather and air quality conditions have been anecdotally reported to be related to symptom fluctuations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), but this has never been empirically investigated. This exploratory study aims to examine the effects of weather and air quality on daily fluctuations of chronic pain and fatigue in women with ME/CFS. In an intensive longitudinal design, 58 participants with ME/CFS provided daily pain and fatigue ratings for an average of 61 days. Daily weather and air quality data were obtained from the National Oceanic and Atmospheric Administration and the US Environmental Protection Agency for the Birmingham, AL area. Linear mixed models revealed a significant relationship between days with more severe pain and worse Air Quality Indices (AQI, p < 0.001), lower wind speeds (p = 0.009), greater particulate matter (p = 0.037), and lower carbon monoxide (p = 0.004), sulfur dioxide (p = 0.003), and ozone levels (p = 0.015). Greater fatigue was associated with more particulates (p = 0.023) and lower barometric pressure (p = 0.048). These results suggest that air quality and weather can have small effects on ME/CFS symptom severity.

Dysregulated metabolic pathways associated with air pollution exposure and the risk of autism: Evidence from epidemiological studies

Autism spectrum disorder (ASD) is a developmental disorder with symptoms that range from social and communication impairments to restricted interests and repetitive behavior and is the 4th most disabling condition for children aged 5-14. Risk factors of ASD are not fully understood. Environmental risk factors are believed to play a significant role in the ASD epidemic. Research focusing on air pollution exposure as an early-life risk factor of autism is growing, with numerous studies finding associations of traffic and industrial emissions with an increased risk of ASD. One of the possible mechanisms linking autism and air pollution exposure is metabolic dysfunction. However, there were no consensus about the key metabolic pathways and corresponding metabolite signatures in mothers and children that are altered by air pollution exposure and cause the ASD. Therefore, we performed a review of published papers examining the metabolomic signatures and metabolic pathways that are associated with either air pollution exposure or ASD risk in human studies. In conclusion, we found that dysregulated lipid, fatty acid, amino acid, neurotransmitter, and microbiome metabolisms are associated with both short-term and long-term air pollution exposure and the risk of ASD. These dysregulated metabolisms may provide insights into ASD etiology related to air pollution exposure, particularly during the perinatal period in which neurodevelopment is highly susceptible to damage from oxidative stress and inflammation.

Effects of triclosan on lipid metabolism and underlying mechanisms in the cyprinid fish Squalidus argentatus

The ubiquitous presence of the disinfectant triclosan (TCS) has raised global concerns regarding its potential threat to aquatic organisms. However, the effects of TCS on lipid metabolism in fish and its underlying mechanisms remain unclear. This study investigated the effect of environmentally relevant levels of TCS on the lipid metabolism in the cyprinid fish Squalidus argentatus. Our results showed that the lipid metabolism in the cyprinid fish S. argentatus was perturbed by 28-day exposure to TCS, as evidenced by higher levels of lipid accumulation in both the liver and blood. To elucidate the mechanisms underlying toxicity, we evaluated oxidative stress, inflammatory status, and lipase activity in the liver. Our findings indicated increased ROS-specific fluorescence intensity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in the livers of S. argentatus exposed to TCS, suggesting oxidative damage. Additionally, TCS treatment induced the production of proinflammatory cytokines in the liver of S. argentatus exposed to TCS, which suppressed hepatic lipase activity. Intestinal tissue morphology, inflammation, and blood lipopolysaccharide (LPS) levels were also examined. Significant increases in goblet cell count and MDA levels were observed in the intestinal tract. After 28 days of TCS exposure, the serum LPS levels were significantly elevated. 16S rRNA sequencing was conducted to analyze the effects of TCS on the diversity and composition of the intestinal microbiota. Transcriptomic analysis was performed to reveal global molecular alterations following TCS exposure. In conclusion, our results indicate that TCS may disrupt the lipid metabolism in S. argentatus by (i) inducing hepatic oxidative stress and inflammation, which suppress lipoprotein lipase activity, (ii) affecting the production of beneficial metabolites and endotoxins by dysregulating gut microbiota composition, and (iii) altering the expression levels of lipid metabolism-related pathways.

Prenatal PM2.5 Exposure Associated with Neonatal Gut Bacterial Colonization and Early Children's Cognitive Development

Previous research indicated that fine particulate matter (PM2.5) exposure affected both offspring neurodevelopment and the colonization of gut microbiota (GM), while the underlying mechanism remained unclear. Our study aimed to evaluate the impacts of prenatal PM2.5 exposure on child cognitive development and investigate the role of neonatal GM colonization in the association. Based on the Shanghai Maternal-Child Pairs Cohort, 361 maternal-child pairs were recruited. Prenatal PM2.5 exposure concentrations were estimated using a high-spatial-resolution prediction model, and child neurodevelopment was assessed by the Ages and Stages Questionnaire. Multivariable linear regression models, logistic regression models, linear discriminant analysis effect size, and random forest model were applied to explore the associations among PM2.5 exposure, GM colonization, and children's neurodevelopment. The present study revealed a negative correlation between PM2.5 exposure throughout pregnancy and child neurodevelopment. Prenatal PM2.5 exposure was associated with an increased risk of suspected developmental delay (SDD) (OR = 1.683, 95% CI: 1.138, 2.489) in infants aged 2 months. Additionally, potential operational taxonomic unit markers were identified for PM2.5-related neurotoxicity, demonstrating promising classification potential for early SDD screening (AUC = 71.27%). Prenatal PM2.5 exposure might disrupt the composition, richness, and evenness of meconium GM, thereby influencing cognitive development and the occurrence of SDD in offspring. Seven PM2.5-related genera, Ruminococcus gnavus group, Romboutsia, Burkholderiaceae Caballeronia Paraburkholderia, Blautia, Alistipes, Parabacteroides, and Bacteroides, were validated as correlated with prenatal PM2.5 exposure and the occurrence of SDD. Moreover, alterations of GM related to PM2.5 exposure and SDD might be accompanied by changes in functional pathways of amino acid, lipid, and vitamin metabolism as indicated by differentially enriched species in the Kyoto Encyclopedia of Genes and Genomes.

Involvement of autophagy and gut dysbiosis in ambient particulate matter-induced colonic inflammation

Ambient fine particulate matter (PM2.5), a vital environmental toxicant, not only adversely affects the cardiovascular and respiratory systems but also potentially exhibits an association with intestinal inflammation and colorectal cancer (CRC). The underlying molecular mechanisms of PM2.5 impacts on CRC are still unclear. In this study, we utilized collected ambient PM2.5 and standard reference material SRM2786 to investigate the toxic effects on the colon through in vivo chronic exposure mouse and in vitro cell culture models. We employed a chronic mouse exposure model to clarify the colonic injury and gut microbiome biomarkers. Prolonged exposure to PM2.5 via oropharyngeal aspiration led to a significant rise in colonic epithelial proliferation and reduced colon length in mice. It triggered characteristics indicative of gut microbiota dysbiosis linked to inflammatory bowel disease. The gut microbiome alternations may serve as a biomarker indicating the colonic health impacts of PM2.5 exposure. PM2.5 and SRM2786-induced cytotoxicity manifested as autophagy dysregulation-mediated abnormal proliferation, IL-8 production, p62/SQSTM1 accumulation, and lysosomal membrane damage in human colon cells WiDr and Caco-2. Both PM2.5 and SRM2786 exposures led to the accumulation of p62/SQSTM1 and compromised lysosomal membrane integrity, showing impaired autophagic flux in WiDr and Caco-2 cells. Finally, we examined the correlations between atmospheric PM2.5 data and biomarkers of colonic inflammation in human population. The serum level of IL-8 was significantly correlated with regional anthropogenic pollutants. In conclusion, our findings elucidate that ambient PM2.5 exhibits adverse effects on colon health manifested as inflammation, aberrant proliferation, and gut dysbiosis, potentially mediated through autophagy dysregulation, thereby highlighting the importance of further research on the impact of environmental pollutants on gastrointestinal health.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

The influence of air pollution on skin microbiome: a link to skin barrier dysfunction

An equilibrium of skin microbiome is crucial for maintaining skin barrier function. However, external factors such as air pollution have the potential to disrupt this equilibrium. Hence, further investigation into the influence of air pollution on the skin microbiome emerges as a critical imperative. Healthy women matched for age from two different ambient air cities in Thailand: Bangkok, characterized by highly polluted air (HPA) (n = 33), and Songkhla, characterized by less polluted air (LPA) (n = 33) were recruited. Skin barrier physiological parameters were measured on the forehead skin. Microbiome samples were collected via the scraping and swabbing technique from the forehead skin and analyzed for microbiome profiles using amplicon sequencing. We found that the abundant microbiome at the phylum level was comparable between HPA- and LPA-exposed skin. However, microbiome diversity was decreased at genus level of fungus and species level of bacteria on HPA-exposed skin. Interestingly, some relatively higher enriched microbiome correlated with skin barrier physiological parameters. Specifically, a higher enrichment of Streptococcus parasanguinis on LPA-exposed skin correlated with both lower skin pH and higher stratum corneum (SC) hydration. Conversely, a higher enrichment of Malassezia spp. and Aureobasidum spp. on HPA-exposed skin was correlated with increased transepidermal water loss and decreased SC hydration, respectively. In conclusion, air pollution potentially affects the skin microbiome by reducing its diversity, disrupting its beneficial correlations with barrier physiology, and promoting the overgrowth of pathogenic microbiome, resulting in decreased hydration and increased pH levels. These factors could ultimately lead to skin barrier dysfunction.

Air-Pollution-Mediated Microbial Dysbiosis in Health and Disease: Lung-Gut Axis and Beyond

Growing evidence suggests physiological and pathological functions of lung and gut microbiomes in various pathologies. Epidemiological and experimental data associate air pollution exposure with host microbial dysbiosis in the lungs and gut. Air pollution through increased reactive oxygen species generation, the disruption of epithelial barrier integrity, and systemic inflammation modulates microbial imbalance. Microbiome balance is crucial in regulating inflammation and metabolic pathways to maintain health. Microbiome dysbiosis is proposed as a potential mechanism for the air-pollution-induced modulation of pulmonary and systemic disorders. Microbiome-based therapeutic approaches are increasingly gaining attention and could have added value in promoting lung health. This review summarizes and discusses air-pollution-mediated microbiome alterations in the lungs and gut in humans and mice and elaborates on their role in health and disease. We discuss and summarize the current literature, highlight important mechanisms that lead to microbial dysbiosis, and elaborate on pathways that potentially link lung and lung microbiomes in the context of environmental exposures. Finally, we discuss the lung-liver-gut axis and its potential pathophysiological implications in air-pollution-mediated pathologies through microbial dysbiosis.

Crohn's Disease Mortality and Ambient Air Pollution in New York City

BACKGROUND

The worldwide increase in Crohn's disease (CD) has accelerated alongside rising urbanization and accompanying decline in air quality. Air pollution affects epithelial cell function, modulates immune responses, and changes the gut microbiome composition. In epidemiologic studies, ambient air pollution has a demonstrated relationship with incident CD and hospitalizations. However, no data exist on the association of CD-related death and air pollution.

METHODS

We conducted an ecologic study comparing the number of CD-related deaths of individuals residing in given zip codes, with the level of air pollution from nitric oxide, nitrogen dioxide, sulfur dioxide (SO2), and fine particulate matter. Air pollution was measured by the New York Community Air Survey. We conducted Pearson correlations and a Poisson regression with robust standard errors. Each pollution component was modeled separately.

RESULTS

There was a higher risk of CD-related death in zip codes with higher levels of SO2 (incidence rate ratio [IRR], 1.16; 95% confidence interval [CI], 1.06-1.27). Zip codes with higher percentage of Black or Latinx residents were associated with lower CD-related death rates in the SO2 model (IRR, 0.58; 95% CI, 0.35-0.98; and IRR, 0.13; 95% CI, 0.05-0.30, respectively). There was no significant association of either population density or area-based income with the CD-related death rate.

CONCLUSIONS

In New York City from 1993 to 2010, CD-related death rates were higher among individuals from neighborhoods with higher levels of SO2 but were not associated with levels of nitric oxide, nitrogen dioxide, and fine particulate matter. These findings raise an important and timely public health issue regarding exposure of CD patients to environmental SO2, warranting further exploration.

An integrative exploration of environmental stressors on the microbiome-gut-brain axis and immune mechanisms promoting neurological disorders

The microbiome-gut-brain axis is altered by environmental stressors such as heat, diet, and pollutants as well as microbes in the air, water, and soil. These stressors might alter the host's microbiome and symbiotic relationship by modifying the microbial composition or location. Compartmentalized mutualistic microbes promote the beneficial interactions in the host leading to circulating metabolites and hormones such as insulin and leptin that affect inter-organ functions. Inflammation and oxidative stress induced by environmental stressors may alter the composition, distribution, and activities of the microbes in the microbiomes such that the resultant metabolite and hormone changes are no longer beneficial. The microbiome-gut-brain axis and immune adverse changes that may accompany environmental stressors are reviewed for effects on innate and adaptive immune cells, which may make host immunity less responsive to pathogens and more reactive to self-antigens. Cardiovascular and fluid exchanges to organs might adversely alter organ functionality. Organs, especially the brain, need a consistent supply of nutrients and clearance of debris; disruption of these exchanges by stressors, and involvement of gut microbiome are discussed regarding neural dysfunctions with Alzheimer's disease, autistic spectrum disorders, viral infections, and autoimmune diseases. The focus of this review includes the manner in which environmental stressors may disrupt gut microbiota leading to adverse immune and hormonal influences on development of neuropathology related to hyperhomocysteinemia, inflammation, and oxidative stress, and how certain therapeutics may be beneficial. Strategies are explored to lessen detrimental effects of environmental stressors on central and peripheral health navigated toward (1) understanding neurological disorders and (2) promoting environmental and public health and well-being.

Air pollution, dysbiosis and diseases: pneumonia, asthma, COPD, lung cancer and irritable bowel syndrome

With substantial effects on human health, air pollution has become a major global concern. Air pollution has been linked to numerous gastrointestinal and respiratory diseases with increasing mortalities. The gut and respiratory dysbiosis brought about by air pollution has recently received much attention. This review attempts to provide an overview of the types of air pollutants, their sources, their impact on the respiratory and gut dysbiotic patterns and their correlation with five major diseases including pneumonia, asthma, COPD, lung cancer and irritable bowel syndrome. Deeper insights into the links between pollutants, dysbiosis and disease may pave the way for novel diagnostic biomarkers for prognosis and early detection of these diseases, as well as ways to ease the disease burden.

The influence of pre- and postnatal exposure to air pollution and green spaces on infant's gut microbiota: Results from the MAMI birth cohort study

BACKGROUND

Animal and human studies indicate that exposure to air pollution and natural environments might modulate the gut microbiota, but epidemiological evidence is very scarce.

OBJECTIVES

To assess the potential impact of pre- and postnatal exposure to air pollution and green spaces on infant gut microbiota assembly and trajectories during the first year of life.

METHODS

MAMI ("MAternal MIcrobes") birth cohort (Valencia, Spain, N = 162) was used to study the impact of environmental exposure (acute and chronic) on infant gut microbiota during the first year of life (amplicon-based 16S rRNA sequencing). At 7 days and at 1, 6 and 12 months, residential pre- and postnatal exposure to air pollutants (NO2, black carbon -BC-, PM2.5 and O3) and green spaces indicators (NDVI and area of green spaces at 300, 500 and 1000 m buffers) were obtained. For the association between exposures and alpha diversity indicators linear regression models (cross-sectional analyses) and mixed models, including individual as a random effect (longitudinal analyses), were applied. For the differential taxon analysis, the ANCOM-BC package with a log count transformation and multiple-testing corrections were used.

RESULTS

Acute exposure in the first week of life and chronic postnatal exposure to NO2 were associated with a reduction in microbial alpha diversity, while the effects of green space exposure were not evident. Acute and chronic (prenatal or postnatal) exposure to NO2 resulted in increased abundance of Haemophilus, Akkermansia, Alistipes, Eggerthella, and Tyzerella populations, while increasing green space exposure associated with increased Negativicoccus, Senegalimassilia and Anaerococcus and decreased Tyzzerella and Lachnoclostridium populations.

DISCUSSION

We observed a decrease in the diversity of the gut microbiota and signs of alteration in its composition among infants exposed to higher levels of NO2. Increasing green space exposure was also associated with changes in gut microbial composition. Further research is needed to confirm these findings.

Unveiling the ecotoxicological impact of microplastics on organisms - the persistent organic pollutant (POP): A comprehensive review

Microplastics have been ubiquitous in our environment for decades, and numerous studies have revealed their extensive dispersion, reaching far beyond the surface of the land, soil, aquatic ecosystems. They have infiltrated the food-chain, the food web, even the air we breathe, as well as the water we drink. Microplastics have been detected in the food we consume, acting as vectors for hazardous chemicals that adhere to their hydrophobic surfaces. This can result in the transfer of these chemicals to the aquatic life, posing a threat to their well-being. The release of microplastics into different environmental settings can give rise to various eco-toxicological implications. The substantial body of literature has led scientists to the consensus that microplastic pollution is a global problem with the potential to impact virtually any type of ecosystem. This paper aims to discuss crucial information regarding the occurrence, accumulation, and ecological effects of microplastics on organisms. It also highlights the new and emerging disease named "Plasticosis" that is directly linked to microplastics and its toxicological effects like permanent scarring and long-term inflammation in the digestive system of the seabirds. By comprehending the behaviour of these microplastic pollutants in diverse habitats and evaluating their ecological consequences, it becomes possible to facilitate a better understanding of this toxicological issue.

Could environmental exposure and climate change Be a key factor in the rising incidence of early onset colorectal cancer?

The emergence of early onset colorectal cancer (EOCRC) is believed to result from the complex interplay between external environmental factors and internal molecular processes. This review investigates the potential association between environmental exposure to chemicals and climate change and the increased incidence of EOCRC, focusing on their effects on gut microbiota (GM) dynamics. The manuscript explores the birth cohort effect, suggesting that individuals born after 1950 may be at higher risk of developing EOCRC due to cumulative environmental exposures. Furthermore, we also reviewed the impact of environmental pollution, including particulate matter and endocrine disrupting chemicals (EDCs), as well as global warming, on GM disturbance. Environmental exposures have the potential to disrupt GM composition and diversity, leading to dysbiosis, chronic inflammation, and oxidative stress, which are known risk factors associated with EOCRC. Particulate matter can enter the gastrointestinal tract, modifying GM composition and promoting the proliferation of pathogenic bacteria while diminishing beneficial bacteria. Similarly, EDCs, can induce GM alterations and inflammation, further increasing the risk of EOCRC. Additionally, global warming can influence GM through shifts in gut environmental conditions, affecting the host's immune response and potentially increasing EOCRC risk. To summarize, environmental exposure to chemicals and climate change since 1950 has been implicated as contributing factors to the rising incidence of EOCRC. Disruptions in gut microbiota homeostasis play a crucial role in mediating these associations. Consequently, there is a pressing need for enhanced environmental policies aimed at minimizing exposure to pollutants, safeguarding public health, and mitigating the burden of EOCRC.

Characterization of microplastics in skim-milk powders

The diffusion of microplastics in the food supply chain is prompting public concern as their impact on human health is still largely unknown. The aim of this study was to qualitatively and quantitatively characterize microplastics in skim-milk powder samples (n = 16) from different European countries (n = 8) through Fourier-transform infrared microspectroscopy in attenuated total reflectance mode analysis. The present study highlights that the use of hot alkaline digestion has enabled the efficacious identification of microplastics in skim-milk powders used for cheesemaking across European countries. The adopted protocol allowed detection of 29 different types of polymeric matrices for a total of 536 plastic particles. The most abundant microplastics were polypropylene, polyethylene, polystyrene, and polyethylene terephthalate. Microplastics were found in skim-milk powders in 3 different shapes (fiber, sphere, and irregular fragments) and 6 different colors (black, blue, brown, fuchsia, green, and gray). Results demonstrate the presence of microplastics in all skim-milk powder samples, suggesting a general contamination. Results of the present study will help to evaluate the impact of microplastics intake on human health.

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.

Association of environmental polycyclic aromatic hydrocarbons exposure with periodontitis in NHANES 2009-2014: A mixtures approach

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) can invade and cause harm to the human body through various pathways, but there is currently little research on the relationship between mixed-PAHs exposure and periodontitis. The purpose of this study was to examine the effects of mixed-urinary PAHs exposure on periodontitis in adults in the United States.

METHODS

The cross-sectional study included 2749 subjects selected from the National Health and Nutrition Examination Survey (NHANES) 2009-2014 cycles. A professional examination of the periodontal status was conducted to distinguish between periodontitis and non-periodontitis based on the Centers for Disease Control and Prevention/American Academy of Periodontology (CDC/AAP) case definition. Laboratory testing of urine samples was performed to obtain the levels of urinary PAHs. Pearson correlation coefficients were utilized to determine the degree of correlation between urinary PAHs, while weighted binary logistic regression and Bayesian kernel machine regression (BKMR) were employed to evaluate the relationship between urinary PAHs and periodontitis.

RESULTS

In a single-exposure model, 3-hydroxyfluorene (OH-3F), 2-hydroxyfluorene (OH-2F), 1-hydroxyphenanthrene (OH-1Ph), and 2-hydroxyphenanthrene and 3-hydroxyphenanthrene (OH-2,3Ph) were positively associated with periodontitis risk. In the mixed-exposure model, BKMR analysis demonstrated that mixed exposure to urinary PAHs was positively associated with periodontitis, with OH-2F being the most critical factor for the overall mixed effects (posterior inclusion probability [PIP] = 0.98). Univariate exposure-response function and univariate effects analysis revealed a positive correlation between urinary OH-2F levels and periodontitis.

CONCLUSIONS

The study reveals a significant positive correlation between exposure to mixed PAHs and periodontitis, with a particular emphasis on the pivotal role of OH-2F. Mitigating PAHs in the environment may serve as a preventive measure against periodontitis and alleviate its global public health burden.

The combined exposure of polystyrene microplastics and high-fat feeding affects the intestinal pathology damage and microbiome in zebrafish

The pervasive utilization of plastics and their integration into ecosystems has resulted in significant environmental issues, particularly the pollution of microplastics (MPs). In aquaculture, high-fat feed (HFD) is frequently employed to enhance the energy intake and economic fish production. This study utilized zebrafish as a model organism to investigate the impact of concurrent exposure to HFD and MPs on fish intestinal pathology damage and intestinal microbiome. The experimental design involved the division of zebrafish into two groups: one receiving a normal diet (ND) and the other receiving HFD. The zebrafish were exposed to a control group, as well as polystyrene (PS) MPs of varying sizes (5 and 50 μm). Histopathological examination revealed that the combination of 5 μm MPs and HFD resulted in the most significant damage to the zebrafish intestinal tract. Furthermore, gut microbiome assays indicated that exposure to MPs and HFD altered the composition of the gut microbiome. This study demonstrates that in aquaculture, the issue of HFD must be considered alongside concerns about MPs contamination, as both factors appear to have a combined effect on the intestinal pathology damage and intestinal microbiome. The findings of this research offer valuable insights for the improvement of fish farming practices.

Impact of climate change on atopic dermatitis: A review by the International Eczema Council

Atopic dermatitis (AD), the most burdensome skin condition worldwide, is influenced by climatic factors and air pollution; however, the impact of increasing climatic hazards on AD remains poorly characterized. Leveraging an existing framework for 10 climatic hazards related to greenhouse gas emissions, we identified 18 studies with evidence for an impact on AD through a systematic search. Most climatic hazards had evidence for aggravation of AD the impact ranged from direct effects like particulate matter-induced AD exacerbations from wildfires to the potential for indirect effects like drought-induced food insecurity and migration. We then created maps comparing the past, present, and future projected burden of climatic hazards to global AD prevalence data. Data are lacking, especially from those regions most likely to experience more climatic hazards. We highlight gaps important for future research: understanding the synergistic impacts of climatic hazards on AD, long-term disease activity, the differential impact on vulnerable populations, and how basic mechanisms explain population-level trends.

The silent threat: Nanopolystyrene and chrysene pollutants disrupt the intestinal mucosal barrier, new insights from juvenile Siniperca chuatsi

The intestinal mucosal barrier-comprising microbial, mechanical, chemical, and immunological barriers-is critical to protection against pathogens and maintenance of host health; however, it remains unclear whether it is affected by environmental contaminants. Therefore, the present study assessed whether exposure to ambient concentrations of nanopolystyrene (NP) and chrysene (CHR)-two ubiquitous environmental pollutants in the aquatic environment-affect the intestinal mucosal barrier in juvenile Siniperca chuatsi. After exposure for 21 days, S. chuatsi exhibited intestinal oxidative stress and imbalance of intestinal microbial homeostasis. NP and/or CHR exposure also disrupted the intestinal mechanical barrier, as evidenced by the altered intestinal epithelial cell morphology, disrupted structure of intercellular tight junctions, and decreased expression of tight junction proteins. Damage to the intestinal chemical barrier manifested as thinning of the mucus layer owing to the loss and damage of goblet cells. Furthermore, the intestinal immunological barrier was impaired as indicated by the loss of intestinal intraepithelial lymphocytes and increase in pro-inflammatory cytokines, chemokines, and immunoglobulins. These findings collectively suggest that the intestinal mucosal barrier was damaged. This study is, to the best of our knowledge, the first to report that exposure to NP and/or CHR at environmentally relevant concentrations disrupts the intestinal mucosal barrier in organisms and highlight the significance of nanoplastic/CHR pollution for intestinal health.

Pollutants, microbiota and immune system: frenemies within the gut

Pollution is a critical concern of modern society for its heterogeneous effects on human health, despite a widespread lack of awareness. Environmental pollutants promote several pathologies through different molecular mechanisms. Pollutants can affect the immune system and related pathways, perturbing its regulation and triggering pro-inflammatory responses. The exposure to several pollutants also leads to alterations in gut microbiota with a decreasing abundance of beneficial microbes, such as short-chain fatty acid-producing bacteria, and an overgrowth of pro-inflammatory species. The subsequent intestinal barrier dysfunction, together with oxidative stress and increased inflammatory responses, plays a role in the pathogenesis of gastrointestinal inflammatory diseases. Moreover, pollutants encourage the inflammation-dysplasia-carcinoma sequence through various mechanisms, such as oxidative stress, dysregulation of cellular signalling pathways, cell cycle impairment and genomic instability. In this narrative review, we will describe the interplay between pollutants, gut microbiota, and the immune system, focusing on their relationship with inflammatory bowel diseases and colorectal cancer. Understanding the biological mechanisms underlying the health-to-disease transition may allow the design of public health policies aimed at reducing the burden of disease related to pollutants.

Short-term exposures to PM2.5, PM2.5 chemical components, and antenatal depression: Exploring the mediating roles of gut microbiota and fecal short-chain fatty acids

BACKGROUND

PM2.5 and its chemical components increase health risks and are associated with depression and gut microbiota. However, there is still limited evidence on whether gut microbiota and short-chain fatty acids (SCFAs) mediate the association between PM2.5, PM2.5 chemical components, and antenatal depression. The purpose of this study was to investigate the mediating role of maternal gut microbiota in correlations between short-term exposure to PM2.5, short-term exposure to PM2.5 chemical components, and antenatal depression.

METHODS

Demographic information and stool samples were collected from 75 pregnant women in their third trimester. Their exposure to PM2.5 and PM2.5 chemical components was measured. Participants were divided into the non-antenatal depression group or the antenatal depression group according to the cut-off of 10 points on the Edinburgh Postnatal Depression Scale (EPDS). The gut microbiota were analyzed using the 16 S rRNA-V3/V4 gene sequence, and the concentration of PM2.5 and its chemical components was calculated using the Tracking Air Pollution in China (TAP) database. Gas chromatography-mass spectrometry was used to analyze SCFAs in stool samples. In order to assess the mediating effects of gut microbiota and SCFAs, mediation models were utilized.

RESULTS

There were significant differences between gut microbial composition and SCFAs concentrations between the non-antenatal depression group and the antenatal depression group. PM2.5 and its chemical components were positively associated with EPDS scores and negatively associated with genera Enterococcus and Enterobacter. Genera Candidatus_Soleaferrea (β = -7.21, 95%CI -11.00 to -3.43, q = 0.01) and Enterococcus (β = -2.37, 95%CI -3.87 to -0.87, q = 0.02) were negatively associated with EPDS scores, indicating their potential protective effects against antenatal depression. There was no significant association between SCFAs and EPDS scores. The mediating role of Enterococcus between different lagged periods of PM2.5, PM2.5 chemical component exposure, and antenatal depression was revealed. For instance, Enterococcus explained 29.23% (95%CI 2.16-87.13%, p = 0.04) of associations between PM2.5 exposure level at the day of sampling (lag 0) and EPDS scores.

CONCLUSION

Our study highlights that Enterococcus may mediate the associations between PM2.5, PM2.5 chemical components, and antenatal depression. The mediating mechanism through which the gut microbiota influences PM2.5-induced depression in pregnant women still needs to be further studied.

The microbiota and T cells non-genetically modulate inherited phenotypes transgenerationally

The host-microbiota relationship has evolved to shape mammalian physiology, including immunity, metabolism, and development. Germ-free models are widely used to study microbial effects on host processes such as immunity. Here, we find that both germ-free and T cell-deficient mice exhibit a robust sebum secretion defect persisting across multiple generations despite microbial colonization and T cell repletion. These phenotypes are inherited by progeny conceived during in vitro fertilization using germ-free sperm and eggs, demonstrating that non-genetic information in the gametes is required for microbial-dependent phenotypic transmission. Accordingly, gene expression in early embryos derived from gametes from germ-free or T cell-deficient mice is strikingly and similarly altered. Our findings demonstrate that microbial- and immune-dependent regulation of non-genetic information in the gametes can transmit inherited phenotypes transgenerationally in mice. This mechanism could rapidly generate phenotypic diversity to enhance host adaptation to environmental perturbations.

Impact of ambient air pollution on colorectal cancer risk and survival: insights from a prospective cohort and epigenetic Mendelian randomization study

BACKGROUND

This study investigates the associations between air pollution and colorectal cancer (CRC) risk and survival from an epigenomic perspective.

METHODS

Using a newly developed Air Pollutants Exposure Score (APES), we utilized a prospective cohort study (UK Biobank) to investigate the associations of individual and combined air pollution exposures with CRC incidence and survival, followed by an up-to-date systematic review with meta-analysis to verify the associations. In epigenetic two-sample Mendelian randomization analyses, we examine the associations between genetically predicted DNA methylation related to air pollution and CRC risk. Further genetic colocalization and gene-environment interaction analyses provided different insights to disentangle pathogenic effects of air pollution via epigenetic modification.

FINDINGS

During a median 12.97-year follow-up, 5767 incident CRC cases among 428,632 participants free of baseline CRC and 533 deaths in 2401 patients with CRC were documented in the UK Biobank. A higher APES score was associated with an increased CRC risk (HR, 1.03, 95% CI = 1.01-1.06; P = 0.016) and poorer survival (HR, 1.13, 95% CI = 1.03-1.23; P = 0.010), particularly among participants with insufficient physical activity and ever smokers (Pinteraction > 0.05). A subsequent meta-analysis of seven observational studies, including UK Biobank data, corroborated the association between PM2.5 exposure (per 10 μg/m3 increment) and elevated CRC risk (RR,1.42, 95% CI = 1.12-1.79; P = 0.004; I2 = 90.8%). Genetically predicted methylation at PM2.5-related CpG site cg13835894 near TMBIM1/PNKD and cg16235962 near CXCR5, and NO2-related cg16947394 near TMEM110 were associated with an increased CRC risk. Gene-environment interaction analysis confirmed the epigenetic modification of aforementioned CpG sites with CRC risk and survival.

INTERPRETATION

Our study suggests the association between air pollution and CRC incidence and survival, underscoring the possible modifying roles of epigenomic factors. Methylation may partly mediate pathogenic effects of air pollution on CRC, with annotation to epigenetic alterations in protein-coding genes TMBIM1/PNKD, CXCR5 and TMEM110.

FUNDING

Xue Li is supported by the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province (LR22H260001), the National Nature Science Foundation of China (No. 82204019) and Healthy Zhejiang One Million People Cohort (K-20230085). ET is supported by a Cancer Research UK Career Development Fellowship (C31250/A22804). MGD is supported by the MRC Human Genetics Unit Centre Grant (U127527198).

Air pollutants, genetic susceptibility, and the risk of incident gastrointestinal diseases: A large prospective cohort study

A comprehensive overview of the associations between air pollution and the risk of gastrointestinal (GI) diseases has been lacking. We aimed to examine the relationships of long-term exposure to ambient particulate matter (PM) with aerodynamic diameter ≤2.5 μm (PM2.5), 2.5-10 μm (PMcoarse), ≤10 μm (PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOx), with the risk of incident GI diseases, and to explore the interplay between air pollution and genetic susceptibility. A total of 465,703 participants free of GI diseases in the UK Biobank were included at baseline. Land use regression models were employed to calculate the residential air pollutants concentrations. Cox proportional hazard models were used to evaluate the associations of air pollutants with the risk of GI diseases. The dose-response relationships of air pollutants with the risk of GI diseases were evaluated by restricted cubic spline curves. We found that long-term exposure to ambient air pollutants was positively associated with the risk of peptic ulcer (PM2.5 : Q4 vs. Q1: hazard ratio (HR) 1.272, 95% confidence interval (CI) 1.179-1.372, NO2: 1.220, 1.131-1.316, and NOx: 1.277, 1.184-1.376) and chronic gastritis (PM2.5: 1.454, 1.309-1.616, PM10 : 1.232, 1.112-1.366, NO2: 1.456, 1.311-1.617, and NOx: 1.419, 1.280-1.574) after Bonferroni correction. Participants with high genetic risk and high air pollution exposure had the highest risk of peptic ulcer, compared to those with low genetic risk and low air pollution exposure (PM2.5: HR 1.558, 95%CI 1.384-1.754, NO2: 1.762, 1.395-2.227, and NOx: 1.575, 1.403-1.769). However, no significant additive or multiplicative interaction between air pollution and genetic risk was found. In conclusion, long-term exposure to ambient air pollutants was associated with increased risk of peptic ulcer and chronic gastritis.

Effect of aerobic exercise and particulate matter exposure duration on the diversity of gut microbiota

Inhalation of ambient particulate matter (PM) can disrupt the gut microbiome, while exercise independently influences the gut microbiome by promoting beneficial bacteria. In this study, we analyzed changes in gut microbial diversity and composition in response to combined interventions of PM exposure and aerobic exercise, extending up to 12 weeks. This investigation was conducted using mice, categorized into five groups: control group (Con), exercise group (EXE), exercise group followed by 3-day exposure to PM (EXE + 3-day PM), particulate matter exposure (PM), and PM exposure with concurrent treadmill exercise (PME). Notably, the PM group exhibited markedly lower alpha diversity and richness compared to the Con group and our analysis of beta diversity revealed significant variations among the intervention groups. Members of the Lachnospiraceae family showed significant enhancement in the exercise intervention groups (EXE and PME) compared to the Con and PM groups. The biomarker Lactobacillus, Coriobacteraceae, and Anaerofustis were enriched in the EXE group, while Desulfovibrionaceae, Mucispirillum schaedleri, Lactococcus and Anaeroplasma were highly enriched in the PM group. Differential abundance analysis revealed that Paraprevotella, Bacteroides, and Blautia were less abundant in the 12-week PM exposure group than in the 3-day PM exposure group. Moreover, both the 3-day and 12-week PM exposure groups exhibited a reduced relative abundance of Bacteroides uniformis, SMB53, and Staphylococcus compared to non-PM exposure groups. These findings will help delineate the possible roles and associations of altered microbiota resulting from the studied interventions, paving the way for future mechanistic research.

Effects of inhaled fine particulate matter on the lung injury as well as gut microbiota in broilers

Fine particulate matter (PM2.5) has been widely regarded as an important environmental risk factor that has widely influenced health of both animals and humans. Lung injury is the main cause of PM2.5 affecting respiratory tract health. Gut microbiota participates in the development of lung injury in many pathological processes. However, there is still unknown the specific effects of PM2.5 on the gut-lung axis in broilers. Thus, we conducted a broiler model based on 3-wk-old male Arbor Acres broiler to explore the underlying mechanism. Our results showed that PM2.5 exposure triggered TLR4 signaling pathway and induced the increase of IL-6, IFN-γ, TNF-α expression as well as the decrease of IL-10 expression in the lung. Inhaled PM2.5 exposure significantly altered the gut microbiota diversity and community. Specifically, PM2.5 exposure decreased α diversity and altered β diversity of gut microbiota, and reduced the abundance of DTU089, Oscillospirales, Staphylococcus, and increased the Escherichia-Shigella abundance, leading to the increase of gut-derived lipopolysaccharides (LPS). Moreover, PM2.5 significantly disrupted the intestinal epithelial barrier by reducing the expression of muc2 and claudin-1 to increase intestinal permeability, which possibly facilitated the LPS translocation into the blood. Spearman analysis revealed that gut microbiota dysbiosis was positively related to TLR4, TNF-α, and IFN-γ expression in the lung. In summary, our results showed that PM2.5 exposure induced lung injury by causing inflammation and triggering TLR4 signaling pathway, and also induced gut microbiota dysbiosis resulting in the overproduction of gut-derived LPS. And gut microbiota dysbiosis may be associated with lung injury. The above results provide basis data to comprehend the potential role of gut microbiota dysbiosis in the lung injury as well as providing a new regulatory target for alleviating lung injury associated with environmental pollutants.

The hidden threat: Environmental toxins and their effects on gut microbiota

The human gut microbiota (GM), which consists of a complex and diverse ecosystem of bacteria, plays a vital role in overall wellness. However, the delicate balance of this intricate system is being compromised by the widespread presence of environmental toxins. The intricate connection between contaminants in the environment and human well-being has garnered significant attention in recent times. Although many environmental pollutants and their toxicity have been identified and studied in laboratory settings and animal models, there is insufficient data concerning their relevance to human physiology. Consequently, research on the toxicity of environmental toxins in GM has gained prominence in recent years. Various factors, such as air pollution, chemicals, heavy metals, and pesticides, have a detrimental impact on the composition and functioning of the GM. This comprehensive review aims to comprehend the toxic effects of numerous environmental pollutants, including antibiotics, endocrine-disrupting chemicals, heavy metals, and pesticides, on GM by examining recent research findings. The current analysis concludes that different types of environmental toxins can lead to GM dysbiosis and have various potential adverse effects on the well-being of animals. We investigate the alterations to the GM composition induced by contaminants and their impact on overall well-being, providing a fresh perspective on research related to pollutant exposure.

Long-term exposure to ambient fine particulate matter constituents and mortality from total and site-specific gastrointestinal cancer

BACKGROUND

Ambient fine particulate matter (PM2.5) exposure has been associated with an increased risk of gastrointestinal cancer mortality, but the attributable constituents remain unclear.

OBJECTIVES

To investigate the association of long-term exposure to PM2.5 constituents with total and site-specific gastrointestinal cancer mortality using a difference-in-differences approach in Jiangsu province, China during 2015-2020.

METHODS

We split Jiangsu into 53 spatial units and computed their yearly death number of total gastrointestinal, esophagus, stomach, colorectum, liver, and pancreas cancer. Utilizing a high-quality grid dataset on PM2.5 constituents, we estimated 10-year population-weighted exposure to black carbon (BC), organic carbon (OC), sulfate, nitrate, ammonium, and chloride in each spatial unit. The effect of constituents on gastrointestinal cancer mortality was assessed by controlling time trends, spatial differences, gross domestic product (GDP), and seasonal temperatures.

RESULTS

Overall, 524,019 gastrointestinal cancer deaths were ascertained in 84.77 million population. Each interquartile range increment of BC (0.46 μg/m3), OC (4.56 μg/m3), and nitrate (1.41 μg/m3) was significantly associated with a 27%, 26%, and 34% increased risk of total gastrointestinal cancer mortality, respectively, and these associations remained significant in PM2.5-adjusted models and constituent-residual models. We also identified robust associations of BC, OC, and nitrate exposures with site-specific gastrointestinal cancer mortality. The mortality risk generally displayed increased trends across the total exposure range and rose steeper at higher levels. We did not identify robust associations for sulfate, ammonium, or chlorine exposure. Higher mortality risk ascribed to constituent exposures was identified in total gastrointestinal and liver cancer among women, stomach cancer among men, and total gastrointestinal and stomach cancer among low-GDP regions.

CONCLUSIONS

This study offers consistent evidence that long-term exposure to PM2.5-bound BC, OC, and nitrate is associated with total and site-specific gastrointestinal cancer mortality, indicating that these constituents need to be controlled to mitigate the adverse effect of PM2.5 on gastrointestinal cancer mortality.

The potential toxicity of microplastics on human health

Microplastics are plastic particles, films, and fibers with a diameter of < 5 mm. Given their long-standing existence in the environment and terrible increase in annual emissions, concerns were raised about the potential health risk of microplastics on human beings. In particular, the increased consumption of masks during the COVID-19 pandemic has dramatically increased human contact with microplastics. To date, the emergence of microplastics in the human body, such as feces, blood, placenta, lower airway, and lungs, has been reported. Related toxicological investigations of microplastics were gradually increased. To comprehensively illuminate the interplay of microplastic exposure and human health, we systematically reviewed the updated toxicological data of microplastics and summarized their mode of action, adverse effects, and toxic mechanisms. The emerging critical issues in the current toxicological investigations were proposed and discussed. Our work would facilitate a better understanding of MPs-induced health hazards for toxicological evaluation and provide helpful information for regulatory decisions.