The Interplay Between Environmental Pollutants, Gut Microbiota, and Infections: Current Concepts and Therapies

I. Introduction

Environmental pollutants (EPs) are causing widespread concern due to their ecotoxicology and potential hazards to human health, particularly in light of the pervasive and severe pollution of biotic and abiotic environmental compartments (Chen, 2021). A growing body of research shows that being exposed to these EPs is one of the many environmental factors that contribute to the emergence of many health conditions (Claus et al., 2016b). Indeed, it has been established that chronic exposure to contaminants can raise the risk of developing metabolic and cancerous disorders(Chen, 2021). The basic role of gut microbiota (GM) in the upkeep and regulation of general host health has been confirmed in recent years by accumulating research. The GM is a complex community of microbes that produces energy from digested food, controls immunological response, and defends against pathogens(Omar et al., 2022). It comprises bacteria and other microbes such as fungi, archaea, viruses, and protozoans (Omar et al., 2022). Indeed, recent research has shown a significant connection between GM and human health. Through dietary channels, which can directly contact the gut ecosystem and come into contact with the microorganisms that naturally reside there, water and food pollution promote exposure to EPs (Chen, 2021).

GM are very sensitive to drugs, diet, and EPs (Jin et al., 2017a). Indeed, the GM system is commonly targeted and driven to dysbiosis by various pollutants (Chen, 2021). It is widely recognized that a balanced commensal microbiota is essential for defending the host against a variety of infections, either directly by eradicating them or indirectly by suppressing them inside or outside the intestine (Rothschild et al., 2018). Indeed, he human GM comprises thousands of microbes, many of which fight pathogens in infectious diseases and either inhibit or stimulate inflammation in various immunological situations (Maciel-Fiuza et al., 2023). Therefore, changes in the composition, abundance, diversity, and metabolism of the gut microbial population will undermine the physiological activity and fitness of the host, as well as create an imbalance in the host's immune system and raise the risk of infections. These have been shown to influence disease susceptibility and contribute to the pathogenesis of several conditions, including diabetes, obesity, and inflammation (Chen, 2021). There is mounting evidence that the gut microbiome influences the development and progression of various inflammatory and infectious diseases. On the other hand, medical concerns about EPs' effects on animals have grown over the past few years (Jin et al., 2010, 2016; Z. Liu et al., 2016; Lv et al., 2019; Piccioni et al., 2021; Ye et al., 2010), and the subsequent gut dysbiosis associated with high risks of infection.

Considering the crucial role of the host's GM in maintaining health, its disruption (gut dysbiosis) by the effects of EPs (Chen, 2021) leads to several conditions' development. As a result, intervention aiming to restore the functions of the gut microbial population and the integrity of the gut epithelial barrier appears to be a straightforward but practical approach to combating the negative effects of EPs (Chen, 2021). Therefore, it is crucial to comprehend the interplay between intestinal microbiota and the adverse effects of EPs on its function to understand the mechanisms involved in different pathologies and search for new treatments. This chapter overviews the link between EPs and GM dysfunction, their association with infections, and some current therapeutic approaches to restore GM function.