Gut Microbiota and Immunity: Possible Role in Sudden Infant Death Syndrome

Abstract

The gut microbiome influences the development of the immune system of young mammals; the establishment of a normal gut microbiome is thought to be important for the health of the infant during its early development. As the role of bacteria in the causation of sudden infant death syndrome (SIDS) is backed by strong evidence, the balance between host immunity and potential bacterial pathogens is likely to be pivotal. Bacterial colonization of the infant colon is influenced by age, mode of delivery, diet, environment, and antibiotic exposure. The gut microbiome influences several systems including gut integrity and development of the immune system; therefore, gut microflora could be important in protection against bacteria and/or their toxins identified in SIDS infants. The aims of the review are to explore (1) the role of the gut microbiome in relation to the developmentally critical period in which most SIDS cases occur; (2) the mechanisms by which the gut microbiome might induce inflammation resulting in transit of bacteria from the lumen into the bloodstream; and (3) assessment of the clinical, physiological, pathological, and microbiological evidence for bacteremia leading to the final events in SIDS pathogenesis.

Escherichia coli and Sudden Infant Death Syndrome

“…If certain E. coli can cause ARDS, then it is possible that a similar mechanism occurs in SIDS given that the clinical and pathological findings in SIDS babies reflect a process consistent with sepsis and/or toxemic shock. This is supported by sterile site evidence of bacteremia ( 33 , 44 , 45 ) and the knowledge that bacteremia is a profound inducer of hypoxemia (thought to be involved in the final pathway). This model is supported by clinical evidence of fever [sweat-soaked bedding ( 46 ) and raised rectal temperature ( 47 ) and the pathological findings of intrathoracic petechiae, heavy wet lungs, and liquid heart blood and elevated fibrin degradation products ( 48 , 49 )], findings compatible with a process of bacterial sepsis.…”

“…α-hemolysin-producing E. coli needs to be considered in SIDS. The effects of HLyA and/or Ehly on the enterocyte and gut wall integrity could result in mucosal perturbation or damage promoting translocation of bacteria ( E. coli or other gut microbiota) into the bloodstream either through induced inflammation or directly [see below and the accompanying article by Goldwater ( 33 )].…”

Effect of Delivery Mode and Nutrition on Gut Microbiota in Neonates

“…The recent arrival of comprehensive analytical procedures such as 16S rRNA gene sequencing and next-generation sequencing has enabled wide-ranging analyses of species to be performed, and has accelerated the studies of gut microbiota. These revealed that the dysbiosis of gut microbiota is related to the development of various diseases not only during childhood but throughout life, including gastrointestinal diseases such as inflammatory intestinal disorder [3], irritable bowel syndrome [4], and necrotizing enterocolitis [5], as well as allergic diseases [6], obesity or metabolic syndrome [7], diabetes [8], autistic spectrum disorder [9], and sudden infant death syndrome [10].…”

Infection: the neglected paradigm in SIDS research

“…Such a mechanism could operate in SIDS wherein an inflamed gut mucosa could promote microbial translocation into the bloodstream and cause overwhelming sepsis. 74 New information showing an otherwise previously unknown microbiome of the airways and lungs could also involve predisposition to abnormal inflammatory responses. 75 …”