Cytomegalovirus Worsens Necrotizing Enterocolitis Severity in Mice via Increased Toll-Like Receptor 4 Signaling

Background and Aims: Necrotizing enterocolitis (NEC) is a life-threatening condition in premature infants, marked by acute intestinal necrosis. NEC develops in part after activation of the lipopolysaccharide receptor toll-like receptor 4 (TLR4) by intestinal microbes in the intestinal epithelium. Previous authors have shown an increased risk of NEC in human infants after cytomegalovirus (CMV) infection, which can affect mitochondrial function. We now seek to explore the impact and the mechanisms of CMV infection on NEC severity and its relationship with TLR4 signaling and mitochondria function. Methods: NEC was induced in newborn mice with and without CMV infection. RNA sequencing and gene set enrichment analysis were performed to identify effects on inflammatory and metabolic pathways. The role of TLR4 signaling and mitochondrial function were investigated in wild-type and Tlr4-deficient mice. The adenosine receptor agonist 5'-N-ethylcarboxamido adenosine was tested for its ability to reduce CMV-induced effects on NEC severity. Results: CMV infection significantly increased NEC severity in wild-type mice. Mechanistically, CMV infection triggered proinflammatory pathways, disrupted cellular metabolism, and upregulated Tlr4 expression, leading to mitochondrial dysfunction and nuclear factor-kB translocation. These effects were notably absent in Tlr4-deficient mice. 5'-N-ethylcarboxamido adenosine treatment reversed CMV-induced NEC severity by reducing mitochondrial dysfunction and TLR4-driven nuclear factor-kB activation. Conclusions: CMV infection worsens NEC severity in mice by amplifying TLR4 signaling, inflammation, and mitochondrial dysfunction. Targeting CMV and its influence on TLR4 may offer novel therapeutic approaches for NEC.