Figure 6: Model explaining changes in gene expression and the gut.

Circulating lymphocytes expressed high levels of inflammatory markers (TNF-α, NF-κB, IL-1β and SP1). High amounts of innate immune mediators secreted to the bloodstream would be reaching the mucosae of the small and large intestine of VLBW infants with sepsis. This would activate master regulators TNF-α and IL-1β, inducing the expression of pro-inflammatory signaling and innate immune defense systems, such as oxidative stress pathway in the gut mucosal cells. The secretion of ROS and NOS would then correlate with bacterial profiles richer in Enterobacteriaceae and with the lower presence of Bifidobacteriaceae and Bacteroides, due to the lack in the latter of the enzymatic armor to survive in the presence of ROS, RNS and derived toxic compounds.