Gastrointestinal problems, mechanisms and possible therapeutic directions in Gulf war illness: a mini review

Abstract

By its nature, Gulf war illness (GWI) is multisymptomatic and affects several organ systems in the body. Along with other symptoms, veterans who suffer from GWI commonly report chronic gastrointestinal issues such as constipation, pain, indigestion, etc. However, until recently, most attention has been focused on neurological disturbances such as cognitive impairments, chronic fatigue, and chronic pain among affected veterans. With such high prevalence of gastrointestinal problems among Gulf war (GW) veterans, it is surprising that there is little research to investigate the mechanisms behind these issues. This review summarizes all the available works on the mechanisms behind gastrointestinal problems in GWI that have been published to date in various databases. Generally, these studies, which were done in rodent models, in vitro and human cohorts propose that an altered microbiome, a reactive enteric nervous system or a leaky gut among other possible mechanisms are the major drivers of gastrointestinal problems reported in GWI. This review aims to draw attention to the gastrointestinal tract as an important player in GWI disease pathology and a potential therapeutic target.

Dysbiosis in gastrointestinal pathophysiology: Role of the gut microbiome in Gulf War Illness

“…Symptoms range from these related to neurologic/mood/cognition, pain, respiratory, musculoskeletal, gastrointestinal and dermatological system, to overall fatigue 4,19 . Although the range of symptoms reported is broad and diverse, gastrointestinal symptoms are highly prevalent especially in the veterans of GW 11,20 . Diarrhoea was reported by 10%–27% in the GW veterans compared to only 2%–3% in nondeployed troops, 21 indicating the extremely high prevalence of gastrointestinal problems in the GW veterans.…”

“…From the larger number of afferent fibres from gut towards the brain, the communication is considered more in a gut‐to‐brain direction rather than the other way round 24 . Interestingly, the enteric nervous system expresses similar neurotransmitter as the CNS and, presumably because of it, patients with neurodegenerative disorders like Alzheimer and Parkinson patients are reported to often have neurodegenerative pathology in the gastrointestinal system as well 11 . This might be also involved in causing neurological dysfunction and gastrointestinal symptoms in the GWI as well.…”

“…7,8 Among the broad range of the symptoms, the gastrointestinal symptoms such as diarrhoea, nausea and irritable bowel syndrome were a major group of symptoms reported by the GWI veterans. 4,[9][10][11] Even the most commonly reported symptoms, that is chronic fatigue, can also be associated with changes in the gut microbiome. 12,13 Thus, the gastrointestinal system and the gut microbiota can have a significant role in GWI, and the understanding of their roles and the development of treatments targeted to the gastrointestinal system may unravel a breakthrough in treating GWI.…”

“…GW veterans with GWI showed decrease in the gut microbiota (dysbiosis) and alteration in the bacteria species profile. 11,16,17…”

The influence of gut brain axis in neurodegenerative diseases: short review

“…Microbiota is a symbiotic population of bacteria, viruses, fungi, and other microorganisms that coexist in the gastrointestinal tract 30 . The question remains "how can microbes in the gut have an effect in the brain?"…”