High-dimensional mass cytometry reveals systemic and local immune signatures in necrotizing enterocolitis

Mitophagy and immune cell interaction: insights into pathogenesis and potential targets for necrotizing enterocolitis

Background

Neonatal necrotizing enterocolitis (NEC) is a fatal disease in early life characterized by an inflammatory response or even necrosis of the bowel wall. NEC is one of the leading causes of preterm infant mortality. The pathogenesis of NEC is intricate and involves mitochondrial damage to intestinal cells and infiltration of immune cells. However, the specific functions of mitophagy and its association with immune cells in NEC remain unclear. The aim of this study was to explore the pivotal roles of mitophagy and the immune microenvironment in NEC and their potential interactions.

Methods

Microarray data (GSE46619) associated with NEC were obtained from the Gene Expression Omnibus (GEO) at the National Center for Biotechnology Information (NCBI). Differentially expressed genes (DEGs) were screened by GEO2R. Mitophagy gene data were downloaded from the Pathway Unification database and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Consequently, mitophagy-related differentially expressed genes (MRDEGs) were obtained. To identify hub MRDEGs that are closely associated with NEC, we used CytoHubba, Molecular Complex Detection (MCODE) and Comparative Toxicogenomics Database (CTD) scores. Cytoscape and miRWalk databases were used to predict the transcription factors (TFs) and target microRNAs (miRNAs) of hub MRDEGs, respectively, and a regulatory network was established. The ImmuCellAI was used to analyze the pattern of immune infiltration, and the Spearman correlation was used to investigate the relationship between the hub MRDEGs and the abundance of infiltrating immune cells. Finally, the expression levels of the hub MRDEGs were verified by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting in NEC animal model.

Results

A total of 14 up-regulated and 22 down-regulated MRDEGs were identified, these genes exhibited enrichment in mitophagy, and inflammation-related pathways. Furthermore, 13 hub MRDEGs closely related to NEC were identified. The increased presence of immune cells such as neutrophils, M1 macrophages, and activated mast cells were observed while adaptive immune cells including B cells and various T-cell subsets exhibited reduced infiltration. Furthermore, up-regulated MRDEGs were positively correlated with the proinflammatory immune cell infiltration, and the down-regulated MRDEGs were positively correlated with the anti-inflammatory immune cell infiltration. In vivo experiments demonstrated that the expressions of four genes Hif-1a, Acsl4, Pck2, and Aifm1 were consistent with the bioinformatics analysis results.

Conclusions

The potential interplay of mitophagy and immune cells is crucial in the onset and progression of NEC. This perspective opens the door for deeper investigations into NEC pathogenesis, presenting a possible target for disease intervention.

Therapeutic potential of human breast milk-derived exosomes in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe inflammatory and necrotizing disease of the intestine that primarily affects the neonates, particularly premature infants. It has a high incidence of approximately 8.9% in extremely preterm infants, with a mortality rate ranging from 20 to 30%. In recent years, exosomes, particularly those derived from breast milk, have emerged as potential candidates for NEC therapy. Human breast milk-derived exosomes (BME) have been shown to enhance intestinal barrier function, protect intestinal epithelial cells from oxidative stress, promote the proliferation and migration of intestinal epithelial cells, and reduce the severity of experimental NEC models. As a subset of extracellular vesicles, BME possess the membrane structure, low immunogenicity, and high permeability, making them ideal vehicles for the treatment of NEC. Additionally, exosomes derived from various sources, including stem cells, intestinal epithelial cells, plants, and bacteria, have been implicated in the development and protection of intestinal diseases. This article summarizes the mechanisms through which exosomes, particularly BME, exert their effects on NEC and discusses the feasibility and obstacles associated with this novel therapeutic strategy.

Values of serum intestinal fatty acid-binding protein, fecal calprotectin, and fecal human β-defensin 2 for predicting necrotizing enterocolitis

BACKGROUND

This study aimed to assess the diagnostic potential of serum intestinal fatty acid-binding protein (I-FABP), fecal calprotectin (FC), and fecal human β-defensin 2 (hBD2) in predicting necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A prospective cohort of neonates with a gestational age < 32 weeks, suspected of NEC, was enrolled between June 2021 and December 2022. Serum I-FABP, FC, and fecal hBD2 levels were measured upon NEC suspicion, and diagnosis was confirmed through radiological examination or surgical intervention. Diagnostic precision of serum I-FABP, FC, and fecal hBD2 was assessed using a logistic regression model with multiple variables.

RESULTS

The study included 70 neonates (45 males, 25 females), with 30 developing NEC (40% Stage III, n = 12; 60% Stage II, n = 18) and 40 in the control group. NEC patients exhibited significantly higher serum I-FABP and FC levels (4.76 ng/mL and 521.56 µg/g feces, respectively) than those with other diagnoses (1.38 ng/mL and 213.34 µg/g feces, respectively; p ˂ 0.05 for both biomarkers). Stage II NEC neonates showed elevated fecal hBD2 levels (376.44 ng/g feces) than Stage III NEC neonates and controls (336.87 ng/g and 339.86 ng/g feces, respectively; p ˂ 0.05). No such increase was observed in infants progressing to Stage III NEC. Using a serum I-FABP threshold of > 2.54 ng/mL yielded 76.7% sensitivity, 87.5% specificity, 82.1% positive predictive value (PPV), and 83.3% negative predictive value (NPV). For FC (cutoff > 428.99 µg/g feces), corresponding values were 76.7% sensitivity, 67.5% specificity, 63.9% PPV, and 79.4% NPV.

CONCLUSION

Serum I-FABP and FC levels are valuable for early NEC detection and provide insights into disease severity. Low fecal hBD2 levels suggest an inadequate response to luminal bacteria, potentially rendering these infants more susceptible to NEC development or exacerbation.