Lysosomal overloading and necrotizing enterocolitis

Itaconic acid ameliorates necrotizing enterocolitis through the TFEB-mediated autophagy-lysosomal pathway

Excessive autophagy has been implicated in the pathogenesis of necrotizing enterocolitis (NEC), yet the molecular underpinnings of the autophagy-lysosomal pathway (ALP) in NEC are not well characterized. This study aimed to elucidate alterations within the ALP in NEC by employing RNA sequencing on intestinal tissues obtained from affected infants. Concurrently, we established animal and cellular models of NEC to assess the therapeutic efficacy of itaconic acid (ITA). Our results indicate that the ALP is significantly disrupted in NEC. Notably, ITA was found to modulate the ALP, enhancing autophagic flux and lysosomal function, which consequently alleviated NEC symptoms. Further analysis revealed that ITA's beneficial effects are mediated through the promotion of TFEB nuclear translocation, thereby augmenting the ALP. These findings suggest that targeting the ALP with ITA to modulate TFEB activity may represent a viable therapeutic approach for NEC.

Antenatal Ureaplasma infection induces ovine small intestinal goblet cell defects: a strong link with NEC pathology

Disruption of the intestinal mucus barrier and intestinal epithelial endoplasmic reticulum (ER) stress contribute to necrotizing enterocolitis (NEC). Previously, we observed intestinal goblet cell loss and increased intestinal epithelial ER stress following chorioamnionitis. Here, we investigated how chorioamnionitis affects goblet cells by assessing their cellular characteristics. Importantly, goblet cell features are compared with those in clinical NEC biopsies. Mucus thickness was assessed as read-out of goblet cell function. Fetal lambs were intra-amniotically (IA) infected for 7d at 122 gestational age with Ureaplasma parvum serovar-3, the main microorganism clinically associated with chorioamnionitis. After preterm delivery, mucus thickness, goblet cell numbers, gut inflammation, epithelial proliferation and apoptosis and intestinal epithelial ER stress were investigated in the terminal ileum. Next, goblet cell morphological alterations (TEM) were studied and compared to human NEC samples. Ileal mucus thickness and goblet cell numbers were elevated following IA UP exposure. Increased pro-apoptotic ER stress, detected by elevated CHOP-positive cell counts and disrupted organelle morphology of secretory cells in the intestinal epithelium, was observed in IA UP exposed animals. Importantly, comparable cellular morphological alterations were observed in the ileum from NEC patients. In conclusion, UP-driven chorioamnionitis leads to a thickened ileal mucus layer and mucus hypersecretion from goblet cells. Since this was associated with pro-apoptotic ER stress and organelle disruption, mucus barrier alterations seem to occur at the expense of goblet cell resilience and may therefore predispose to detrimental intestinal outcomes. The remarkable overlap of these in utero findings with observations in NEC patients underscores their clinical relevance.

A CRISPR screen in intestinal epithelial cells identifies novel factors for polarity and apical transport

Epithelial polarization and polarized cargo transport are highly coordinated and interdependent processes. In our search for novel regulators of epithelial polarization and protein secretion, we used a genome-wide CRISPR/Cas9 screen and combined it with an assay based on fluorescence-activated cell sorting (FACS) to measure the secretion of the apical brush-border hydrolase dipeptidyl peptidase 4 (DPP4). In this way, we performed the first CRISPR screen to date in human polarized epithelial cells. Using high-resolution microscopy, we detected polarization defects and mislocalization of DPP4 to late endosomes/lysosomes after knockout of TM9SF4, anoctamin 8, and ARHGAP33, confirming the identification of novel factors for epithelial polarization and apical cargo secretion. Thus, we provide a powerful tool suitable for studying polarization and cargo secretion in epithelial cells. In addition, we provide a dataset that serves as a resource for the study of novel mechanisms for epithelial polarization and polarized transport and facilitates the investigation of novel congenital diseases associated with these processes.

Remote ischemic conditioning causes CD4 T cells shift towards reduced cell-mediated inflammation

PURPOSE

Necrotizing enterocolitis (NEC) is a gastrointestinal disease in neonates that is associated with immune-mediated intestinal inflammation. Remote ischemic conditioning (RIC) applied to a limb has been shown to be protective against experimental NEC. In this study, we explore the immune cell-mediated response involved in NEC and the immunomodulatory effects of RIC in an experimental mouse model of the disease.

METHODS

NEC was induced in C57BL/6 mice (ethical approval #58119) pups on postnatal day5 (p5) using gavage hyperosmolar formula, lipopolysaccharide, and hypoxia. RIC consisted of 4 cycles of 5 min ischemia followed by 5 min reperfusion of the right hindlimb during NEC induction on p6 and p8. Breastfed mice were used as control. The mice were sacrificed on p9, with ileal tissue evaluated for inflammatory cytokines and by characterization of T-cell populations.

RESULTS

NEC mice had increased number of CD4⁺ cells indicating an accumulation of T-cells in the mesenchyme of the NEC ileum. Compared to control, NEC pups had upregulated expression pro-inflammatory cytokines (GATA3, IFNγ, IL1β, IL6, IL17, IL22, and TNFα) and reduced anti-inflammatory cytokine (TGFβ). In NEC, there was also a shift in the balance of Treg/Th17 cells towards Th17. Compared to NEC alone, RIC during the course of NEC resulted in reduction of pro-inflammatory cytokines (GATA3, IFNγ, IL1β, IL6, IL17, IL22, and TNFα), increase in anti-inflammatory cytokine TGFβ and concomitant shift back of Th17 cells towards Treg cells.

CONCLUSION

In experimental NEC, remote ischemic conditioning reduces the production of pro-inflammatory markers and increases the production of anti-inflammatory markers. In addition, during NEC, RIC reverses the imbalance of Treg/Th17 providing support for its effect on cell-mediated inflammation. RIC is a non-invasive physical maneuver that can have a significant beneficial effect in reducing the inflammation seen in NEC.

AMPK/PPAR-γ/NF-κB axis participates in ROS-mediated apoptosis and autophagy caused by cadmium in pig liver

The experiment was conducted to investigate the effects of Cadmium (Cd) on growth performance, blood biochemical parameters, oxidative stress, hepatocyte apoptosis and autophagy of weaned piglets. A total of 12 healthy weaned piglets were randomly assigned to the control and the Cd group, which were fed with a basal diet and the basal diet supplemented with 15 ± 0.242 mg/kg CdCl₂ for 30 d, respectively. Our results demonstrated that Cd significantly decreased final body weight, average daily feed intake (ADFI), average daily gain (ADG) and increased feed-to-gain (F/G) ratio (P < 0.05). For blood biochemical parameters, Cd treatment significantly decreased the red blood cell (RBC), hemoglobin (HGB), hematocrit (HCT), total protein, albumin, copper content and iron content (P < 0.05). In addition, liver injury was observed in the Cd-exposed group. Our results also demonstrated that Cd exposure contributed to the production of ROS, activated the AMPK/PPAR-γ/NF-κB pathway (increasing the expressions of P-AMPK/AMPK, NF-κB, I-κB-β, COX-2, and iNOS, decreasing the expressions of PPAR-γ and I-κB-α), finally induced autophagy (increasing the expressions of Beclin-1, the ratio of LC3-II/LC3-I and p62), and apoptosis (increasing the expressions of Bax, Bak, Caspase-9, and Caspase-3, decreasing the expression of Bcl-2). Overall, these findings revealed the vital role of AMPK/PPAR-γ/NF-κB pathway in Cd-induced liver apoptosis and autophagy, which provided deeper insights into a better understanding of Cd-induced hepatotoxicity.

Prenatal Immunity and Influences on Necrotizing Enterocolitis and Associated Neonatal Disorders

Prior to birth, the neonate has limited exposure to pathogens. The transition from the intra-uterine to the postnatal environment initiates a series of complex interactions between the newborn host and a variety of potential pathogens that persist over the first few weeks of life. This transition is particularly complex in the case of the premature and very low birth weight infant, who may be susceptible to many disorders as a result of an immature and underdeveloped immune system. Chief amongst these disorders is necrotizing enterocolitis (NEC), an acute inflammatory disorder that leads to necrosis of the intestine, and which can affect multiple systems and have the potential to result in long term effects if the infant is to survive. Here, we examine what is known about the interplay of the immune system with the maternal uterine environment, microbes, nutritional and other factors in the pathogenesis of neonatal pathologies such as NEC, while also taking into consideration the effects on the long-term health of affected children.

Knockdown of FAM225B inhibits the progression of the hypertrophic scar following glaucoma surgery by inhibiting autophagy

The formation of a hypertrophic scar (HS) may lead to failure of glaucoma surgery. Long non-coding RNAs (lncRNAs) are involved in the formation of HSs. Moreover, family with sequence similarity 225 member B (FAM225B) is upregulated in HS. However, the role of the lncRNA FAM225B in HS remains unknown. Thus, the present study aimed to investigate the function of FAM225B in HS. Scar fibroblasts were isolated from patients who had undergone glaucoma surgery. Western blotting was used to detect the expressions of Bax, Bcl-2, cleaved caspase 3, p62, ATG7 and Beclin 1, and reverse transcription-quantitative PCR (RT-qPCR) were conducted to determine the level of FAM225B in scar fibroblasts. Microtubule associated protein 1 light chain 3 α staining was performed to examine autophagosomes in scar fibroblasts. Furthermore, cell proliferation was evaluated via 5-ethynyl-2′-deoxyuridine staining. Flow cytometry was conducted to determine cell apoptosis and the levels of reactive oxygen species (ROS) in scar fibroblasts. The cell migratory ability was assessed using a Transwell assay. The results demonstrated that FAM225B knockdown significantly attenuated scar fibroblast proliferation and induced apoptosis. Additionally, transfection of scar fibroblasts with FAM225B small interfering RNA (siRNA) significantly increased the ROS levels and significantly decreased the migration of scar fibroblasts. The FAM225B overexpression-induced increase of scar fibroblast proliferation and migration was significantly reversed by 3-methyladenine administration. The results suggested that knockdown of FAM225B significantly inhibited the proliferation of scar fibroblasts by inhibiting autophagy. Therefore, knockdown of FAM225B could inhibit scar fibroblast proliferation after glaucoma surgery by inhibiting autophagy. These findings may provide a novel perspective of developing treatment strategy for the patients with HSs after glaucoma surgery.