β-Carotene Attenuates Apoptosis and Autophagy via PI3K/AKT/mTOR Signaling Pathway in Necrotizing Enterocolitis Model Cells IEC-6

Vitamin A enhances PI3K/Akt signaling and mitigates enterocyte apoptosis in a mouse model of necrotizing enterocolitis

PURPOSE

This study aims to elucidate the roles of the PI3K-Akt signaling pathway and enterocyte apoptosis in necrotizing enterocolitis (NEC) pathogenesis and investigate the impact of vitamin A intervention on these factors.

METHODS

We employed an NEC mouse model and administered vitamin A treatment. Retinol levels in mouse blood were quantified using ELISA. Intestinal cell apoptosis in NEC mice was assessed via the TUNEL assay. We evaluated mRNA and protein expressions of Bcl-2, Bax, cytochrome C (CytoC), Caspase 3, and PI3K/Akt signaling pathway components using qPCR and western blotting.

RESULTS

In NEC models, PI3K, Akt, and Bcl-2 were downregulated, accompanied by upregulated Bax, CytoC, and Caspase 3 at both mRNA and protein levels. These molecular changes were associated with an increase in enterocyte apoptosis in the NEC models. Vitamin A supplementation increased PI3K, Akt, and Bcl-2 expression while decreasing Bax, CytoC, and Caspase 3 levels in the NEC models, resulting in reduced apoptosis.

CONCLUSION

Vitamin A has the potential to mitigate enterocyte apoptosis in NEC by upregulating the PI3K/Akt signaling pathway and modulating apoptotic signals, providing new insights into the inhibitory effect of vitamin A on enterocyte apoptosis in NEC.

Worldwide research tendency and collaborations on models of necrotizing enterocolitis: bibliometric exploration over the past three decades

Background

Necrotizing enterocolitis (NEC) is a devastating disease affecting the gastrointestinal tract in premature infants with high mortality and morbidity. We aimed to analyze the research tendency and collaborations on models of NEC over the past three decades.

Methods

Bibliometric variables of included articles were retrieved from the Web of Science Core Collection from 1994 to 2023. Visualized studies were performed via VOSviewer software. Statistical analysis was applied by using GraphPad Prism and Microsoft Excel.

Result

A total of 255 original articles from 17 countries were included in this study. The number of articles increased significantly from 22 (the year 1994-2003) to 161 (the year 2014-2023) (P < 0.0001). Collaborations in regions and countries have increased significantly over time (P < 0.0001). Developed regions contributed most of the research. While rat (56.08%) held the leading position in all types of models, followed by mouse (30.20%), notably, the proportion of mouse model has increased significantly from 4.55% to 41.36%.

Conclusion

This study might provide valuable insights into the model research of NEC. Research tendency has evolved to be collaborative and inclusive with more collaborations, broad model types, and studies from developing regions. However, the lack of an evident and robust pathophysiology mechanism will continue to make NEC a quite challenging case to decode, and research with strong evidence level and high quality is still required.

miR-375-3p targets YWHAB to attenuate intestine injury in neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a significant contributor to neonatal mortality. This study aimed to investigate the role of high levels of miR-375-3p in breast milk in the development of NEC and elucidate its mechanism.

METHODS

Differential expression of miR-375-3p in the intestines of breast-fed and formula-fed mice was confirmed using real-time polymerase chain reaction (RT-PCR). NEC mice models were established, and intestinal injury was assessed using HE staining. RT-PCR and Western blot were conducted to examine the expression of miR-375-3p, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB), as well as the inflammatory in IEC-6 cells, and intestinal tissues obtained from NEC mice and patients. Flow cytometry and cell counting kit-8 (CCK-8) were employed to elucidate the impact of miR-375-3p and YWHAB on cell apoptosis and proliferation.

RESULTS

Breastfeeding increases miR-375-3p expression in the intestines. The expression of miR-375-3p in NEC intestinal tissues exhibited a significant decrease compared to the healthy group. Additionally, the expression of interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) was higher in the NEC group compared to the control group. Down-regulation of miR-375-3p inhibited IEC-6 cell proliferation, increased apoptosis, and elevated secretion of inflammatory factors. Bioinformatics revealed that YWHAB may be a target of miR-375-3p. RT-PCR and Western blot indicated a down-regulation of YWHAB expression in intestines of NEC patients and mice. Furthermore, YWHAB was found to be positively connected with miR-375-3p. Knockdown miR-375-3p down-regulated YWHAB expression in cells. Inhibition of YWHAB exhibited similar effects to miR-375-3p in IEC-6 cells. YWHAB plasmid partially reverse cellular functional impairment induced by miR-375-3p knockdown.

CONCLUSIONS

Breastfeeding elevated miR-375-3p expression in intestines in neonatal mice. MiR-375-3p leads to a decrease in apoptosis of intestinal epithelial cells, an increase in cell proliferation, and a concomitant reduction in the expression of inflammatory factors partly through targeting YWHAB.

Akt/mTOR Pathway Agonist SC79 Inhibits Autophagy and Apoptosis of Oligodendrocyte Precursor Cells Associated with Neonatal White Matter Dysplasia

White matter dysplasia (WMD) in preterm infants due to intrauterine inflammation is caused by excessive apoptosis of oligodendrocyte precursor cells (OPCs). In recent years, studies have found that excessive autophagy and apoptosis are highly interconnected and important in infection and inflammatory diseases in general. Therefore, in this study, we aimed to confirm whether regulation of autophagy by using the Akt phosphorylation agonist SC79 can inhibit abnormal apoptosis of OPCs and promote myelin maturation and white matter development in neonatal rats with WMD. We investigated the effect of inflammation on oligodendrocyte development in P0 neonatal rats by intracerebellar injection of LPS, and collected brain tissue at P2 and P5. Immunohistochemical and immunofluorescence staining were used to evaluate white matter damage, while immunofluorescence staining, terminal deoxynucleotidyl transferase dUTP nick end labeling analysis (TUNEL), and western blotting were used to evaluate autophagy and apoptosis. First, we observed that white matter development was arrested and white matter fiber maturation was impaired in LPS-inflicted pups compared with those in the sham-operated group. Second, treatment with SC79 reduced the levels of LC3II, caspase 3, caspase 9, and Bax/Bcl-2 and increased the levels of p62, p-Akt, and p-mTOR in the brain tissue of neonatal rats. Finally, SC79 treatment inhibited OPC apoptosis by increasing the binding of Beclin 1 to Bcl-2, which promoted OPC differentiation and maturation. However, the opposite results were observed after rapamycin administration. Taken together, our results suggest that SC79 can inhibit the abnormal apoptosis of OPCs caused by excessive autophagy through the Akt/mTOR pathway and that SC79 is a potential therapeutic agent for WMD in preterm infants.

Programmed death of intestinal epithelial cells in neonatal necrotizing enterocolitis: a mini-review

Necrotizing enterocolitis (NEC) is one of the most fatal diseases in premature infants. Damage to the intestinal epithelial barrier (IEB) is an important event in the development of intestinal inflammation and the evolution of NEC. The intestinal epithelial monolayer formed by the tight arrangement of intestinal epithelial cells (IECs) constitutes the functional IEB between the organism and the extra-intestinal environment. Programmed death and regenerative repair of IECs are important physiological processes to maintain the integrity of IEB function in response to microbial invasion. However, excessive programmed death of IECs leads to increased intestinal permeability and IEB dysfunction. Therefore, one of the most fundamental questions in the field of NEC research is to reveal the pathological death process of IECs, which is essential to clarify the pathogenesis of NEC. This review focuses on the currently known death modes of IECs in NEC mainly including apoptosis, necroptosis, pyroptosis, ferroptosis, and abnormal autophagy. Furthermore, we elaborate on the prospect of targeting IECs death as a treatment for NEC based on exciting animal and clinical studies.