Environmental triggers in IBD: a review of progress and evidence

Abstract

A number of environmental factors have been associated with the development of IBD. Alteration of the gut microbiota, or dysbiosis, is closely linked to initiation or progression of IBD, but whether dysbiosis is a primary or secondary event is unclear. Nevertheless, early-life events such as birth, breastfeeding and exposure to antibiotics, as well as later childhood events, are considered potential risk factors for IBD. Air pollution, a consequence of the progressive contamination of the environment by countless compounds, is another factor associated with IBD, as particulate matter or other components can alter the host's mucosal defences and trigger immune responses. Hypoxia associated with high altitude is also a factor under investigation as a potential new trigger of IBD flares. A key issue is how to translate environmental factors into mechanisms of IBD, and systems biology is increasingly recognized as a strategic tool to unravel the molecular alterations leading to IBD. Environmental factors add a substantial level of complexity to the understanding of IBD pathogenesis but also promote the fundamental notion that complex diseases such as IBD require complex therapies that go well beyond the current single-agent treatment approach. This Review describes the current conceptualization, evidence, progress and direction surrounding the association of environmental factors with IBD.

Systematic review with meta‐analysis: association of vitamin D status with clinical outcomes in adult patients with inflammatory bowel disease

“…47,48 We performed a search of major electronic databases from inception to February 2018. The following databases were included: (1) Medline (Pubmed), (2) EMBASE, (3) Scopus and (4) Web of Science. Our search strategy included the following combinations: (1) 'Vitamin D' [and] 'Inflammatory Bowel Disease', (2) 'Vitamin D' [and] 'Ulcerative Colitis' and (3) 'Vitamin D' [and] 'Crohn's Disease'.…”

“…The incidence and prevalence of IBD is increasing worldwide and is associated with significant healthcare utilisation in the United States . Although the exact aetiology of IBD remains unclear, IBD is speculated to arise from a complex interaction between genetic susceptibility, derangements in immune homeostasis, inappropriate responses to gut microflora and various environmental triggers . Increasing evidence has proposed that vitamin D plays a protective role in the pathogenesis of inflammatory bowel disease .…”

“…2 Although the exact aetiology of IBD remains unclear, IBD is speculated to arise from a complex interaction between genetic susceptibility, derangements in immune homeostasis, inappropriate responses to gut microflora and various environmental triggers. [3][4][5][6][7] Increasing evidence has proposed that vitamin D plays a protective role in the pathogenesis of inflammatory bowel disease. 8,9 Vitamin D has been shown to maintain gut epithelial barrier integrity against inflammatory and pathogenic stimuli.…”

Probiotics Ameliorate Colon Epithelial Injury Induced by Ambient Ultrafine Particles Exposure

“…Recent studies have reported effects on the gastrointestinal tract [1,2] and with an increased risk for appendicitis, digestive tract cancers, and inflammatory bowel disease (IBD). Recent studies have reported effects on the gastrointestinal tract [1,2] and with an increased risk for appendicitis, digestive tract cancers, and inflammatory bowel disease (IBD).…”

At the Intersection of Microbiota and Circadian Clock: Are Sexual Dimorphism and Growth Hormones the Missing Link to Pathology?

“…Moreover, the development of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, are also associated with microbiota dysbiosis, sex hormones levels, as well as perturbation of GH signaling . Interestingly, IBD is also strongly associated with AHR and the environmental pollutants known to activate it . Analogously, the ovarian development of Ahr KO mice presents similarities with PCOS models and the disease is associated with exposure to environmental pollutants .…”