May 30th, 2022

A subset of children may be more susceptible to respiratory infections of viral and bacterial varieties based on some new research. It appears that the microbiomes of the nasopharyngeal respiratory tract and host immune defenses play a major role here. If a child has a defective innate and/or adaptive immune response, then the pathogen will have a chance to grow rapidly and infect the host well.

The immune defenses of a infection prone child are more akin to a newborn than an age matched healthy child. (Picture above from Nature Reviews Microbiology Man 2019)

Dr. Pichichero noted: Dysfunction in innate immune responses that cause an immunopathological impact in the nasopharynx have been discovered including inadequate proinflammatory cytokine response and poor epithelial cell repair. Adaptive immunity defects in B cell function and immunologic memory resulting in low levels of antibody to otopathogen-specific antigens allows repeated infections. CD4+ and CD8+ T cell function and memory defects significantly contribute. (Pichichero ME 2020) From Ren et. al.: The stringent otitis media (sOM) children exhibited significantly more Acute OM episodes per child (8.86-fold higher), viral URIs, and viral URIs followed by AOMs than the Non OP children. The sOP children had lower nasal proinflammatory levels of interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and regulated on activation, normal T-cell–expressed and –secreted (RANTES) than Non OP children during viral URIs. NOP children had higher levels of IL-6, IL-10, interferon-γ, TNF-α, IL-1β, monocyte chemoattractant protein 1, RANTES, IL-2, and IL-17 during viral URIs versus AOMs following the URIs, when compared to sOP children. (Ren Clin Inf Dis 2019)

Take home point: in these susceptible children, the immune system doesn't develop adequate immunity based on exposure or even repeated exposure. This leads to repeated infections of the ears and lungs putting the child at risk for an abnormal microbiome and lots of downstream problems. These results are very similar to other infections like SARS2 and Flu whereby some people get repeatedly infected while others never do. The variability of human immune responses is vast.

What these authors do not discuss is what are the reasons for the poor responses. I submit that I suspect that human behaviors are driving much of this immune weakness as we have seen with Covid disease burden. Many of the lifestyle choices that we have discussed ad nauseam in this newsletter are likely at play including diet, sleep, stress, toxin exposure and much more as each of these can affect immune activity.

The next big issue is the damaged lung and intestinal microbiome following infections and antibiotic exposures. From a Nature article: The respiratory tract is a complex organ system that is responsible for the exchange of oxygen and carbon dioxide. The human respiratory tract spans from the nostrils to the lung alveoli and is inhabited by niche-specific communities of bacteria. The microbiota of the respiratory tract probably acts as a gatekeeper that provides resistance to colonization by respiratory pathogens. The respiratory microbiota might also be involved in the maturation and maintenance of homeostasis of respiratory physiology and immunity. The picture above shows a nice pictorial view of the upstream risk factors to an unstable microbiome.

Dr. Pichichero further noted that children prone to infections are also at increased risk for asthma issues. They noted that the children that had the earliest colonization with a bacterial pathogen had the lowest microbial biodiversity in the lung microbiome. Increased biodiversity in any human locale is highly correlated with health in that region. For humans, it is incumbent upon us to avoid all things in nature or culture that disrupt the microbiome.

Dr. M

Pichichero J Infection
Man Nature
Chapman PLOSOne
Ren Clin Inf Disease