Post-hunter-gatherer era microbes’ role in allergic/autoimmune diseases         

Exploring the microbiome’s potential role in severe COVID-19: possible implications for prevention and treatment

“…Increasing evidence is showing a quite substantial effect, even when the air pollution levels are below national standards [28][29][30], indicating a direct or indirect effect on lung pathology and quite possibly the microbiome. Although there are many potential effects of air pollution, this pattern is compatible with a role for the colonization/infection of microbes associated with air pollution, as described previously [12]. Little research has been done on this so far; however, changes in the nasopharyngeal microbiota were observed after a severe haze event in China [31].…”

“…Little research has been done on this so far; however, changes in the nasopharyngeal microbiota were observed after a severe haze event in China [31]. It is also possible that hard-to-detect low-abundance microbes from the rare biosphere may also produce pro-inflammatory effects [12]. It has been observed that COPD exacerbations are often related to exposures to certain gases and particulate matter [32].…”

“…It seems possible that many of these gases and types of particulate matter, especially from the burning of fossil fuel, may have microbial strains associated with them that humans have not coevolved with. These relatively novel, potentially non-coevolved microbes (PHM) might be more prone to cause increased hypersensitivity reactions [12].…”

“…The rapid changes in diet, lifestyle, environmental exposures and medical interventions in the last 75 years has led to changes in the human microbiome that may not be optimally compatible with our evolved immune responses to pathogens. This perspective is closely related to the hygiene hypothesis [10] and its newer forms, such as the altered microflora hypothesis [11] and an extension of these earlier hypotheses that focuses on the potentially pathogenic microbes within the post-hunter-gatherer era microbiota (PHM) [12]. Throughout this review, attention will be paid to factors that might lead to the establishment of these potentially pathogenic microbes, which include environmental microbes that are less coevolved with their human hosts and thus could have greater immune suppressing/dysregulating potential.…”

“…Throughout this review, attention will be paid to factors that might lead to the establishment of these potentially pathogenic microbes, which include environmental microbes that are less coevolved with their human hosts and thus could have greater immune suppressing/dysregulating potential. healthy state is increased levels of potentially pathogenic species from a variety of endogenous or exogenous sources [12].…”