Necrotizing enterocolitis in premature infants-A defect in the brakes? Evidence from clinical and animal studies

Different infant formulas can activate toll-like receptor 9 in vitro and inhibit interleukin 6 in human primary intestinal epithelial cells

PURPOSE

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal disease in preterm infants caused by an exaggerated intestinal epithelial immune activation. Several studies show that modulation of toll-like receptor 9 (TLR9) activity may have positive effects on preventing intestinal inflammatory mechanisms ultimately resulting in NEC development. In this study, the effect of various infant formulas (IF) and the probiotic strain Limosilactobacillus fermentum CECT5716 on TLR9 activation were analyzed in vitro.

METHODS

First, TLR4 and TLR9 expression was analyzed on human primary intestinal epithelial cells (P-IECs) by qPCR and Western blot analysis. Then genetically designed HEK-Dual™ hTLR9 (NF/IL8) reporter cells (HEK-Dual) were treated with different IFs, L. fermentum CECT5716, and different functional components to measure TLR9 activation via luminescence. Finally, the IFs were investigated in P-IECs to analyze TLR downstream signaling by Western blot analysis.

RESULTS

IFs containing intact protein and L. fermentum CECT5716 activated TLR9 in HEK-Dual cells, but the functional components lactoferrin, L-5-methyltetrahydrofolate, and hydrolyzed whey proteins failed to activate TLR9. In P-IECs, the IFs induced increased phosphorylation of MAPK8/9 of the TLR signaling pathway and significantly reduced IL6 levels. Consistently, IL6 levels were increased in P-IECs when TLR9-signaling was inhibited. Interestingly, L. fermentum CECT5716 enhanced TLR9-signaling and increased NF-kappa-B inhibitor alpha-phosphorylation.

CONCLUSION

We found out that the used control formula, prebiotic formula, prebiotic formula with hydrolyzed-protein, and L. fermentum CECT5716 reduce IL6 levels in human P-IECs through TLR9 activation. L. fermentum CECT5716 and the here tested IFs could be a promising approach for modulation of gut health in infants.

Understanding necrotizing enterocolitis endotypes and acquired intestinal injury phenotypes from a historical and artificial intelligence perspective

Necrotizing enterocolitis (NEC) remains a devastating disease in preterm and term neonates. Despite significant progress made in understanding NEC pathogenesis over the last 50 years, the inability of current definitions to discriminate the various pathophysiological processes underlying NEC has led to an umbrella term that limits clinical and research progress. In this mini review, we provide a historical perspective on how NEC definitions and pathogenesis have evolved to our current understanding of NEC endotypes. We also discuss how artificial intelligence-based approaches are influencing our knowledge of risk-factors, classification and prognosis of NEC and other neonatal intestinal injury phenotypes.

The conundrum of intestinal injury in preterm infants receiving mother's own milk

"Necrotizing enterocolitis" ("NEC") is a heterogeneous group of intestinal injuries experienced primarily in preterm infants. Risk factors include among others preterm gut microbiome alterations. Maternal milk (MM), or otherwise parent milk, is protective for the developing intestine due to its constituents, which include bioactive antimicrobials, immunomodulatory molecules, human milk oligosaccharides (HMOs), secretory immunoglobulin A (sIgA), and microorganisms. However, some preterm infants receiving exclusively mother's own milk (MOM) develop intestinal injuries. Studies showed predisposition to increased risk for "NEC", when a decreased MM HMO, disialyllacto-N-tetraose, is combined with an altered infant's gut microbiome. The intestine may also become more prone to injury with a greater amount of bacteria not bound to IgA. Variations in MM composition may alter the offspring gut microbiome, depriving protection. The different "NEC" entities should be considered to play a role as to why, in many studies, MOM does not provide absolute protection against preterm intestinal injury.

Impact of Clinical Use of Probiotics on Preterm-Related Outcomes in Infants with Extremely Low Birth Weight

Background: Preterm birth significantly contributes to mortality and morbidities, with recent studies linking these issues to gut microbiota imbalances. Probiotic supplementation shows promise in mitigating adverse outcomes in preterm infants, but optimal timing and guidelines remain unclear. This study assesses the benefits of probiotic supplementation for preterm infants without consistent guidelines. Methods: This retrospective study examined extremely low-birth-weight (ELBW) infants in neonatal intensive care units from 2017 to 2021. Mortality and preterm-related outcomes were compared between infants receiving probiotics and those not. Subgroup analyses based on probiotic initiation timing were conducted: early (≤14 days), late (>14 days), and non-probiotic groups. Results: The study included 330 ELBW infants: 206 received probiotics (60 early, 146 late), while 124 did not. Probiotic supplementation was associated with lower overall mortality (adjusted OR 0.22, 95% CI 0.09-0.48) and decreased mortality from necrotizing enterocolitis (NEC) or late-onset sepsis (LOS) (adjusted OR 0.12, 95% CI 0.03-0.45). Early probiotics reduced overall mortality, NEC/LOS-related mortality, and NEC/LOS-unrelated mortality. Late probiotics decreased overall mortality and NEC/LOS-related mortality. Early probiotic use also expedited full enteral feeding achievement. Conclusions: Probiotic supplementation reduces mortality and improves feeding tolerance in preterm infants. Establishing guidelines for probiotic use in this population is crucial.

Gut microbiota differences in five-year-old children that were born preterm with a history of necrotizing enterocolitis: A pilot trial

The study explores the long-term effects of necrotizing enterocolitis (NEC) on gut microbiota in preterm infants by analyzing stool samples from 5-year-old children using shotgun metagenomic sequencing. It compares children with a history of NEC, treated surgically or medically, to preterm controls without NEC. Findings reveal persistent gut microbiota dysbiosis in NEC children, with reduced species diversity and evenness, especially in those treated surgically. The surgical NEC group had a lower Shannon index, indicating less microbial diversity. Significant differences in taxonomic profiles were observed, mainly influenced by surgical treatment. These results underscore the lasting impact of NEC and its treatment on gut microbiota, suggesting a need for strategies addressing long-term dysbiosis.

Role of innate T cells in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a destructive gastrointestinal disease primarily affecting preterm babies. Despite advancements in neonatal care, NEC remains a significant cause of morbidity and mortality in neonatal intensive care units worldwide and the etiology of NEC is still unclear. Risk factors for NEC include prematurity, very low birth weight, feeding with formula, intestinal dysbiosis and bacterial infection. A review of the literature would suggest that supplementation of prebiotics and probiotics prevents NEC by altering the immune responses. Innate T cells, a highly conserved subpopulation of T cells that responds quickly to stimulation, develops differently from conventional T cells in neonates. This review aims to provide a succinct overview of innate T cells in neonates, encompassing their phenotypic characteristics, functional roles, likely involvement in the pathogenesis of NEC, and potential therapeutic implications.

Butyrate suppresses experimental necrotizing enterocolitis-induced brain injury in mice

Background

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants, and 50% of infants with surgical NEC develop neurodevelopmental defects. The mechanisms by which NEC-induced cytokine release and activation of inflammatory cells in the brain mediate neuronal injury, and whether enteral immunotherapy attenuates NEC-associated brain injury remain understudied. Based on our prior work, which demonstrated that experimental NEC-like intestinal injury is attenuated by the short-chain fatty acid, butyrate, in this study, we hypothesize that NEC-induced brain injury would be suppressed by enteral butyrate supplementation.

Methods

A standardized NEC mouse model [enteral formula feeding, lipopolysaccharide (LPS), and hypoxia] was used. Mice were randomized into the following groups: control, NEC, butyrate pretreated NEC, and butyrate control. NEC scoring (1-4 with 4 representing severe injury) was performed on ileal sections using a validated scoring system. Intestinal and brain lysates were used to assess inflammation, proinflammatory signaling, and apoptosis.

Results

NEC-induced intestinal injury was attenuated by butyrate supplementation. NEC-induced microglial activation in the cerebral cortex and hippocampus was suppressed with butyrate. NEC increased the number of activated microglial cells but decreased the number of oligodendrocytes. Butyrate pretreatment attenuated these changes. Increased activation of proinflammatory Toll-like receptor signaling, cytokine expression, and induction of GFAP and IBA1 in the cerebral cortex observed with NEC was suppressed with butyrate.

Conclusion

Experimental NEC induced inflammation and activation of microglia in several regions of the brain, most prominently in the cortex. NEC-induced neuroinflammation was suppressed with butyrate pretreatment. The addition of short-chain fatty acids to diet may be used to attenuate NEC-induced intestinal injury and neuroinflammation in preterm infants.

The Detrimental Effects of Peripartum Antibiotics on Gut Proliferation and Formula Feeding Injury in Neonatal Mice Are Alleviated with Lactobacillus rhamnosus GG

Peripartum antibiotics can negatively impact the developing gut microbiome and are associated with necrotizing enterocolitis (NEC). The mechanisms by which peripartum antibiotics increase the risk of NEC and strategies that can help mitigate this risk remain poorly understood. In this study, we determined mechanisms by which peripartum antibiotics increase neonatal gut injury and evaluated whether probiotics protect against gut injury potentiated by peripartum antibiotics. To accomplish this objective, we administered broad-spectrum antibiotics or sterile water to pregnant C57BL6 mice and induced neonatal gut injury to their pups with formula feeding. We found that pups exposed to antibiotics had reduced villus height, crypt depth, and intestinal olfactomedin 4 and proliferating cell nuclear antigen compared to the controls, indicating that peripartum antibiotics impaired intestinal proliferation. When formula feeding was used to induce NEC-like injury, more severe intestinal injury and apoptosis were observed in the pups exposed to antibiotics compared to the controls. Supplementation with the probiotic Lactobacillus rhamnosus GG (LGG) reduced the severity of formula-induced gut injury potentiated by antibiotics. Increased intestinal proliferating cell nuclear antigen and activation of the Gpr81-Wnt pathway were noted in the pups supplemented with LGG, suggesting partial restoration of intestinal proliferation by probiotics. We conclude that peripartum antibiotics potentiate neonatal gut injury by inhibiting intestinal proliferation. LGG supplementation decreases gut injury by activating the Gpr81-Wnt pathway and restoring intestinal proliferation impaired by peripartum antibiotics. Our results suggest that postnatal probiotics may be effective in mitigating the increased risk of NEC associated with peripartum antibiotic exposure in preterm infants.