Early Microbial–Immune Interactions and Innate Immune Training of the Respiratory System during Health and Disease

Abstract

Over the past two decades, several studies have positioned early-life microbial exposure as a key factor for protection or susceptibility to respiratory diseases. Birth cohorts have identified a strong link between neonatal bacterial colonization of the nasal airway and gut with the risk for respiratory infections and childhood asthma. Translational studies have provided companion mechanistic insights on how viral and bacterial exposures in early life affect immune development at the respiratory mucosal barrier. In this review, we summarize and discuss our current understanding of how early microbial–immune interactions occur during infancy, with a particular focus on the emergent paradigm of “innate immune training”. Future human-based studies including newborns and infants are needed to inform the timing and key pathways implicated in the development, maturation, and innate training of the airway immune response, and how early microbiota and virus exposures modulate these processes in the respiratory system during health and disease.

Early childhood respiratory tract infections according to parental subfertility and conception by assisted reproductive technologies

“…The microbiome has also been shown to be associated with disease susceptibility and at the same time its development is dependent on perinatal factors and breastfeeding ( Rutayisire et al , 2016 ; Princisval et al , 2021 ). Early-life exposure to microbes is inversely associated with later susceptibility towards respiratory diseases ( Nino et al , 2021 ).…”

Dual Effect of Low-Molecular-Weight Bioregulators of Bacterial Origin in Experimental Model of Asthma

“…Proponents of the hygiene hypothesis argued that childhood infections and exposure to microbial components contribute to protection against allergic diseases, including asthma [44]. Since its inception, the hygiene hypothesis has been significantly revised, and the microbiome theory has been formed and revealed the importance of the endogenous microbiota inhabiting all mucous membranes, including human skin, for maintaining immune homeostasis as well as protecting against allergic diseases [45,46]. In this case, of course, it is necessary to take into account both genetic predisposition and violations of the barrier functions of the epithelium under the influence of environmental factors [47].…”

Microbiome First Approaches to Rescue Public Health and Reduce Human Suffering

“…In the airways, epithelial barrier status is critical in the risk of a wide array of airway diseases [88]. Additionally, early microbiota-immune interactions in the airways determine the course of airway mucosal immunity and risk of airway disease [89]. One of the considerations for the airway microimmunosome is whether the pathobiont Staph A is carried in the infant nasal passages.…”