Enterocyte Apoptosis Research Articles

Histopathological Characteristics and Distinction of Immune Checkpoint Inhibitor-Related Colitis

Abstract Introduction/Objective Immune checkpoint inhibitors (ICPIs) represent a groundbreaking class of cancer immunotherapy for patients with various advanced-stage solid cancers. ICPIs have been associated with immune- related adverse events, with ICPI-related colitis being a prominent concern due to its potential for life-threatening clinical complications. Recognizing the histopathologic characteristics specific to ICPI-related colitis is crucial for pathologists to provide an accurate diagnosis. Here we have collected and analyzed colon biopsies from patients with ICPI-related colitis following treatment of ICPIs to identify its distinctive histopathologic features and differentiate it from other colitis. Methods/Case Report Colon biopsies are collected from patients with ICPI-related colitis after receiving CTLA-4 and PD-L1 inhibitors as treatment for advanced melanoma. Histopathological features, including epithelial mucin depletion, enterocyte apoptosis, basal lymphoplasmacytosis, cryptitis, glandular architectural distortion, and granuloma, are compared with those in other colitis including ulcerative colitis, Crohn’s disease, microscopic colitis, ischemic and infectious colitis. Immunohistochemistry is employed to analyze inflammatory cell populations and specific enterocyte subtypes. Results (if a Case Study enter NA) ICPI-related colitis, following treatment with Ipilimumab and Nivolumab, commonly presents as active colitis, either with or without chronic colitis. Less frequently, it manifests as microscopic colitis, infectious or ischemic colitis. The acute active form of ICPI-related colitis resembles acute colitis in infectious or ischemic colitis; however, prominent enterocyte apoptosis and intraluminal apoptotic debris are relatively unique features to ICPI-related colitis. The chronic active form of ICPI-related colitis resembles inflammatory bowel diseases, particularly Crohn’s disease, but ICPI-related colitis exhibits an inflammatory injury more affecting surface mucosa and less basal lymphoplasmacytosis. Notably, the most distinctive feature of ICPI-related colitis is the depletion of specific mucinous epithelium observed in our cohort. Conclusion Recognizing specific histopathologic features of ICPI-related colitis, such as mucinous epithelial depletion, enterocyte apoptosis, and surface-dominant inflammation, are essential for pathologists in accurately diagnosing and distinguishing this disease to ensure proper clinical management for patients receiving ICPI treatment.

Histomorphological and Dynamical Changes in Female River Lampreys during Maturation under Controlled Conditions as a Part of Lamprey Restoration Programs.

More than 40 species of lampreys (Petromyzontiformes) are known worldwide. Some of them are parasitic and feed on the blood of fish or other aquatic animals. Lampreys spawn once in their lifetime, after which they die. One of the representatives of the ichthyofauna of European rivers is the river lamprey, Lampetra fluviatilis. The river lamprey is now an endangered species due to loss and degradation of their habitats. The present study investigated gonadal development without hormonal stimulation in female river lampreys during puberty under controlled conditions for a period of seven months. Female river lampreys were kept in conditions that mimicked the natural environment. During the November-May period, samples were taken monthly to determine the extent of gonadal development and gastrointestinal and liver changes using histological examination. From the results obtained, the dynamical changes were determined for the following: gonadosomatic index (GSI; %), hepatosomatic index (his; %), and digestivesomatic index (DSI; %). With the gonadal development of female lampreys, an increase in GSI (7-23%; November-May) and a decrease in DSI (0.4-0.1%; November-May) histological changes were observed in the gonads (oocyte development), intestines (over time, decreased lipid vacuoles and enterocyte apoptosis), and in the liver (decreased lipid vacuoles and hepatocyte apoptosis over time) and in the digestive system resulting from its degradation. Also, it was observed that there was a change in the color of the liver to green in April. This study demonstrated the key role of the liver in the oocyte maturation process in this species.

Mitochondrial Aldehyde Dehydrogenase 2 (ALDH2) Protects against Binge Alcohol-Mediated Gut and Brain Injury.

Mitochondrial aldehyde dehydrogenase-2 (ALDH2) metabolizes acetaldehyde to acetate. People with ALDH2 deficiency and Aldh2-knockout (KO) mice are more susceptible to alcohol-induced tissue damage. However, the underlying mechanisms behind ALDH2-related gut-associated brain damage remain unclear. Age-matched young female Aldh2-KO and C57BL/6J wild-type (WT) mice were gavaged with binge alcohol (4 g/kg/dose, three doses) or dextrose (control) at 12 h intervals. Tissues and sera were collected 1 h after the last ethanol dose and evaluated by histological and biochemical analyses of the gut and hippocampus and their extracts. For the mechanistic study, mouse neuroblast Neuro2A cells were exposed to ethanol with or without an Aldh2 inhibitor (Daidzin). Binge alcohol decreased intestinal tight/adherens junction proteins but increased oxidative stress-mediated post-translational modifications (PTMs) and enterocyte apoptosis, leading to elevated gut leakiness and endotoxemia in Aldh2-KO mice compared to corresponding WT mice. Alcohol-exposed Aldh2-KO mice also showed higher levels of hippocampal brain injury, oxidative stress-related PTMs, and neuronal apoptosis than the WT mice. Additionally, alcohol exposure reduced Neuro2A cell viability with elevated oxidative stress-related PTMs and apoptosis, all of which were exacerbated by Aldh2 inhibition. Our results show for the first time that ALDH2 plays a protective role in binge alcohol-induced brain injury partly through the gut-brain axis, suggesting that ALDH2 is a potential target for attenuating alcohol-induced tissue injury.

Collagen hydrogel protects intestinal epithelial cells from indomethacin-induced damage: results of an in vitro experiment

INTRODUCTION. Indomethacin is a derivative of indoleacetic acid and has anti-inflammatory, analgesic and antipyretic effects. However, the results of numerous studies show that indomethacin, like many other nonsteroidal anti-inflammatory drugs (NSAIDs), have an inhibitory effect on the viability and functional activity of enterocytes. In this regard, the search for new ways to reduce the severity of side effects from the use of NSAIDs remains relevant. One of these approaches may be to enrich patients’ diets with non-drug biologically active compounds, including proteins. However, the effect of dietary proteins and biologically active peptides on NSAID-induced damage to the wall of the small intestine and stomach has not been sufficiently studied. AIM. To evaluate the ability of a collagen-containing dietary supplement to protect human duodenal epithelial cells (HuTu-80 line) from indomethacin-induced damage. MATERIALS AND METHODS. The composite collagen-containing hydrogel was provided by «FIRST ALIVE COLLAGEN» LLC (Russia) and is a registered dietary supplement. The work used a commercial culture of human skin fibroblast cells and human duodenal epithelial cells (line HuTu-80). The viability of intestinal cells and fibroblasts was assessed using light and fluorescence microscopy and flow cytometry methods. RESULTS AND DISCUSSION. It has been established that indomethacin inhibits cell growth, causes apoptosis and death of enterocytes, and also leads to the accumulation of cells in the S-phase, which indicates a disruption in the regulation of the cell cycle. It was revealed that collagen hydrogel prevents cell death caused by indomethacin and reduces the number of apoptotic cells in the population. The protective effect of collagen hydrogel is characterized by normalization of the cell cycle of enterocytes and restoration of their growth and proliferative activity. CONCLUSION. Thus, collagen hydrogel, in vitro, is able to reduce the pathogenic effect of indomethacin on human intestinal epithelial cells. The protective effect of collagen hydrogel is characterized by maintaining viability, inhibiting apoptotic processes, and maintaining cell cycle stability. The results obtained indicate the prospects of using a dietary supplement based on a composite collagen hydrogel as a prophylactic agent to reduce the risk of NSAID-associated gastrointestinal diseases. However, to confirm the therapeutic effectiveness of the dietary supplement, further research is necessary, both using experimental animal modeling of NSAID-associated diseases of the human gastrointestinal tract, and clinical studies.

Protective effect of Broussonetia papyrifera leaf polysaccharides on intestinal integrity in a rat model of diet-induced oxidative stress

This study aimed to investigate the effect of Broussonetia papyrifera polysaccharides (BPP) on the jejunal intestinal integrity of rats ingesting oxidized fish oil (OFO) induced oxidative stress. Polysaccharides (Mw 16,956 Da) containing carboxyl groups were extracted from Broussonetia papyrifera leaves. In vitro antioxidant assays showed that this polysaccharide possessed antioxidant capabilities. Thirty-two male weaned rats were allocated into two groups orally infused BPP solution and PBS for 26 days, respectively. From day 9 to day 26, half of the rats in each group were fed food containing OFO, where the lipid peroxidation can induce intestinal oxidative stress. OFO administration resulted in diarrhea, decreased growth performance (p < 0.01), impaired jejunal morphology (p < 0.05) and antioxidant capacity (p < 0.01), increased the levels of ROS and its related products, IL-1β and IL-17 (p < 0.01) of jejunum, as well as down-regulated Bcl-2/Bax (p < 0.01) and Nrf2 signaling (p < 0.01) of jejunum in rats. BPP gavage effectively alleviated the negative effects of OFO on growth performance, morphology, enterocyte apoptosis, antioxidant capacity and inflammation of jejunum (p < 0.05) in rats. In the oxidative stress model cell assay, the use of receptor inhibitors inhibited the enhancement of antioxidant capacity by BPP. These results suggested that BPP protected intestinal morphology, thus improving growth performance and reducing diarrhea in rats ingesting OFO. This protective effect may be attributed to scavenging free radicals and activating the Nrf2 pathway, which enhances antioxidant capacity, consequently reducing inflammation and mitigating intestinal cell death.

Bacillus amyloliquefaciens SC06 Relieving Intestinal Inflammation by Modulating Intestinal Stem Cells Proliferation and Differentiation via AhR/STAT3 Pathway in LPS-Challenged Piglets.

Bacillus amyloliquefaciens is a well-accepted probiotic, with many benefits for both humans and animals. The ability of intestinal stem cells (ISCs) to develop into several intestinal epithelial cell types helps accelerate intestinal epithelial regeneration. Limited knowledge exists on how bacteria regulated ISCs proliferation and regeneration. Our study investigated the effects of Bacillus amyloliquefaciens supplementation on ISC proliferation and regeneration and intestinal mucosal barrier functions in piglets exposed to lipopolysaccharide (LPS). Eighteen piglets (male, 21 days old) were randomly split into 3 clusters: CON cluster, LPS cluster, and SC06+LPS cluster. On day 21, 100 μg/kg body weight of LPS was intraperitoneally administered to the SC06+LPS and LPS groups. We found SC06 supplementation maintained the intestinal barrier integrity, enhanced intestinal antioxidant capacity, reduced generation of inflammatory response, and suppressed enterocyte apoptosis against the deleterious effects triggered by LPS. In addition, our research indicated that the SC06 supplementation not only improved the ISC regeneration, but also resulted in upregulation of aryl hydrocarbon receptor (AhR) in LPS-challenge piglets. Further studies showed that SC06 also induced ISC differentiation toward goblet cells and inhibited their differentiation to intestinal absorptive cells and enterocytes. The coculture system of SC06 and ileum organoids revealed that SC06 increased the growth of ISCs and repaired LPS-induced organoid damage through activating the AhR/STAT3 signaling pathway. These findings showed that SC06, possibly through the AhR/STAT3 pathway, accelerated ISC proliferation and promoted epithelial barrier healing, providing a potential clinical treatment for IBD. Our research demonstrated that SC06 is effective in preventing intestinal epithelial damage after pathological injury, restoring intestinal homeostasis, and maintaining intestinal epithelial regeneration.

Recombinant IGF-1/BP3 protects against intestinal injury in a neonatal mouse NEC model.

Recombinant human IGF-1/binding protein-3 (rhIGF-1/BP3) is currently being tested in phase II clinical trials in premature infants to prevent bronchopulmonary dysplasia, but its impact on the neonatal intestine remains unclear. The aim of this study was to determine whether rhIGF-1/BP3 protects against necrotizing enterocolitis (NEC) in mice and to investigate the mechanisms involved. Neonatal mice were dam fed or injected intraperitoneally with rhIGF-1/BP3 (or vehicle) and submitted to an experimental NEC model. Serum IGF-1 was assessed by ELISA and intestinal vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) expression by Western blot. Intestinal endothelial cell proliferation, and enterocyte proliferation and migration were examined by immunofluorescence. Pup survival and histological intestinal injury were determined. In pups exposed to experimental NEC, serum IBP3-bound IGF-1 level was decreased. Exogenous rhIGF-1/BP3 preserved VEGF and VEGFR2 protein expression, decreased vascular permeability, and preserved endothelial cell proliferation in the small intestine. Furthermore, rhIGF-1/BP3 promoted enterocyte proliferation and migration, which effects were attenuated by inhibiting VEGFR2 signaling, decreased enterocyte apoptosis and decreased systemic and intestinal inflammation. rhIGF-1/BP3 improved survival and reduced the incidence of severe intestinal injury in experimental NEC. Exogenous rhIGF-1/BP3 protects neonatal mice against experimental NEC via multiple mechanisms. Exogenous rhIGF-1/BP3 preserves intestinal microvascular development and integrity, promotes enterocyte proliferation and migration, decreases local and systemic inflammation, and protects neonatal mice against NEC. The article adds pre-clinical evidence of a protective role for rhIGF-1/BP3 on the premature gut. It provides evidence supporting the use of rhIGF1/BP3 in premature neonates to protect against NEC.

Immune checkpoint inhibitor-related colitis in patients on immunotherapy for cancer.

Immune checkpoint inhibitors, a revolutionary class of cancer immunotherapy drugs, have transformed cancer treatment by bolstering antitumor immunity for various advanced-stage solid cancers. The US Food and Drug Administration has approved 7 immune checkpoint inhibitors that target 3 major immune checkpoint proteins: cytotoxic T-lymphocyte-associated protein 4, programmed cell death 1 protein, and programmed cell death 1 ligand 1. In addition to their remarkable efficacy, however, these inhibitors have been observed causing immune-related adverse events, particularly immune checkpoint inhibitor-related colitis, which often results in severe or life-threatening clinical issues. The diagnosis of immune checkpoint inhibitor-related colitis relies on incorporation of clinical evaluation as well as endoscopic and histopathologic examination, with exclusion of other potential etiologies. The common histopathologic manifestations of immune checkpoint inhibitor-related colitis are acute active colitis, chronic active colitis, microscopic colitis (collagenous or lymphocytic), and ischemic colitis, with patterns overlapping. Notably, enterocyte apoptosis is a unique feature of immune checkpoint inhibitor toxicity. The proposed mechanisms for the pathogenesis of immune checkpoint inhibitor-related colitis are primarily associated with autoimmune-type dysregulation and gut microbiome alteration. This review summarizes the clinical and pathologic characteristics of immune checkpoint inhibitor-related colitis and elucidates its underlying pathogenic mechanisms. Future successful management of this form of colitis relies on our comprehension of the intricate interplay between tumoral and systemic immune responses to immune checkpoint inhibitors and innovative approaches to modify these responses, along with specific immune cell populations, to preclude immune-related adverse events while achieving antitumor therapeutic outcomes.

Protective effects of Lactobacillus on heat stress-induced intestinal injury in finisher broilers by regulating gut microbiota and stimulating epithelial development

Heat stress (HS) is a critical challenge in broilers due to the high metabolic rate and lack of sweat glands. Results from this study show that implementing a cyclic chronic HS (34 °C for 7 h/d) to finisher broilers decreased the diversity of cecal microbiota and impaired intestinal barrier, resulting in gut leak and decreased body weight (both P < 0.05). These alterations might be related to inflammatory outbursts and the retarded proliferation of intestinal epithelial cells (IECs) according to the transcriptome analysis. Considering the potential beneficial properties of Lactobacillus on intestinal development and function, the protective effects of Lactobacillus rhamnosus (L. rhamnosus) on the intestine were investigated under HS conditions in this study. Orally supplemented L. rhamnosus improved the composition of cecal microbiota and upregulated the transcription of tight junction proteins in both duodenum and jejunum, with a consequent suppression in intestinal gene expressions of pro-inflammatory cytokines and facilitation in digestive capability. Meanwhile, the jejunal villus height of the birds that received L. rhamnosus was significantly higher compared with those treated with the broth (P < 0.05). The expression abundances of genes related to IECs proliferation and differentiation were increased by L. rhamnosus, along with upregulated mRNA levels of Wnt3a and β-catenin in jejunum. In addition, L. rhamnosus attenuated enterocyte apoptosis as indicated by decreased caspase-3 and caspase-9 gene expressions. The results indicated that oral administration with L. rhamnosus mitigated HS-induced dysfunction by promoting intestinal development and epithelial maturation in broilers and that the effects of L. rhamnosus might be dependent of Wnt/β-catenin signaling.

Autophagy and Apoptosis in Inflammatory Bowel Disease

The pathogenesis of inflammatory bowel disease (IBD) implicates several interconnecting factors. Immunity and external factors interact, and most aspects are still under investigation. Autophagy and apoptosis are two critical pathways that decide the fate of the individual cells of the intestinal mucosa. Experimental and clinical data indicate that the two are closely interconnected and usually mutually exclusive. However, despite the abundant information on their role, very limited translation into therapeutic application has been seen during recent years. In this review, research on these two pathways is presented. After a general overview of autophagy and apoptosis, their association with IBD, including the important mitophagy and ferroptosis, is discussed. The influence of autophagy- and apoptosis-related genes is also discussed. Finally, the interplay of autophagy and apoptosis in IBD is presented and the implications for treatment applications are examined. It is shown that dysregulated autophagy leads to increased apoptosis of enterocytes and impairs the tight junction proteins of the protective intestinal barrier. Dysregulated autophagy also induces the downregulation of lysozyme and the other antimicrobial proteins’ production. Mucus production by the goblet cells is also reduced due to defective autophagy and increased apoptosis.

MicroRNA-223 Inhibits Soybean Glycinin- and β-Conglycinin-Induced Apoptosis of IPEC-J2 Cells by Targeting NLRP-3 in the IEL/IPEC-J2 Co-culture System.

The apoptosis of intestinal porcine epithelial cells induced by soybean antigen protein allergy is one of the most important mechanisms responsible for enteritis. MicroRNAs (miRNAs) affect the cellular and physiological functions of all multicellular organisms. We hypothesize that microRNA-223 inhibits soybean glycinin- and β-conglycinin-induced apoptosis of intestinal porcine enterocytes (IPEC-J2) by targeting the NLR family pyrin domain containing 3 (NLRP-3). Using the intestinal interepithelial lymphocyte (IEL)/IPEC-J2 co-culture system as an in vitro model, we investigate the role of microRNA-223 in the regulation of soybean glycinin- and β-conglycinin-induced apoptosis. In co-cultured IEL/IPEC-J2 cells incubated with glycinin or β-conglycinin, microRNA-223 decreased NLRP-3, ASC, caspase-1, caspase-3, FAS, BCL-2, and APAF-1 expressions in IPEC-J2 cells; decreased cytokine and cyclooxygenase-2 levels; significantly increased cell activity; and inhibited apoptosis. These data supported a novel antiallergic mechanism to mitigate the sensitization of soybean antigenic protein, which involves the upregulation of microRNA-223-targeting NLRP-3.

MiR-200a attenuated oxidative stress, inflammation, and apoptosis in dextran sulfate sodium-induced colitis through activation of Nrf2.

Oxidative stress and inflammatory responses are critical factors in ulcerative colitis disease pathogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) modulates oxidative stress and suppresses inflammatory responses, and the protective benefits of Nrf2 activation have been associated with the therapy of ulcerative colitis. MicroRNA-200a (miR-200a) could target Kelch-like ECH-associated protein 1 (Keap1) and activate the Nrf2-regulated antioxidant pathway. Nevertheless, whether miR-200a modulates the Keap1/Nrf2 pathway in dextran sulfate sodium (DSS)-induced colonic damage is unknown. Here, our research intends to examine the impact of miR-200a in the model of DSS-induced colitis. Prior to DSS intervention, we overexpressed miR-200a in mice for four weeks using an adeno-associated viral (AAV) vector to address this problem. ELISA detected the concentration of inflammation-related cytokines. The genes involved in inflammatory reactions and oxidative stress were identified using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence. Moreover, we applied siRNAs to weakened Nrf2 expression to confirm the hypothesis that miR-200a provided protection via Nrf2. The present study discovered miR-200a down-regulation, excessive inflammatory activation, enterocyte apoptosis, colonic dysfunction, and Keap1/Nrf2 antioxidant pathway inactivation in mouse colitis and NCM460 cells under DSS induction. However, our data demonstrated that miR-200a overexpression represses Keap1 and activates the Nrf2 antioxidant pathway, thereby alleviating these adverse alterations in animal and cellular models. Significantly, following Nrf2 deficiency, we failed to observe the protective benefits of miR-200a against colonic damage. Taken together, through activating the Keap1/Nrf2 signaling pathway, miR-200a protected against DSS-induced colonic damage. These studies offer an innovative therapeutic approach for ulcerative colitis.

Alterations in gut immunological barrier in SARS-CoV-2 infection and their prognostic potential.

Although coronavirus disease 2019 (COVID-19) is primarily associated with mild respiratory symptoms, a subset of patients may develop more complicated disease with systemic complications and multiple organ injury. The gastrointestinal tract may be directly infected by SARS-CoV-2 or secondarily affected by viremia and the release of inflammatory mediators that cause viral entry from the respiratory epithelium. Impaired intestinal barrier function in SARS-CoV-2 infection is a key factor leading to excessive microbial and endotoxin translocation, which triggers a strong systemic immune response and leads to the development of viral sepsis syndrome with severe sequelae. Multiple components of the gut immune system are affected, resulting in a diminished or dysfunctional gut immunological barrier. Antiviral peptides, inflammatory mediators, immune cell chemotaxis, and secretory immunoglobulins are important parameters that are negatively affected in SARS-CoV-2 infection. Mucosal CD4+ and CD8+ T cells, Th17 cells, neutrophils, dendritic cells, and macrophages are activated, and the number of regulatory T cells decreases, promoting an overactivated immune response with increased expression of type I and III interferons and other proinflammatory cytokines. The changes in the immunologic barrier could be promoted in part by a dysbiotic gut microbiota, through commensal-derived signals and metabolites. On the other hand, the proinflammatory intestinal environment could further compromise the integrity of the intestinal epithelium by promoting enterocyte apoptosis and disruption of tight junctions. This review summarizes the changes in the gut immunological barrier during SARS-CoV-2 infection and their prognostic potential.

Maltol attenuates polystyrene nanoplastic-induced enterotoxicity by promoting AMPK/mTOR/TFEB-mediated autophagy and modulating gut microbiota

The production and application of nanoplastics has been increased during decades, and the enterotoxicity caused by their bioaccumulation has attracted vast attention. Maltol was proved to exert a protective effect on gut damage induced by carbon tetrachloride and cisplatin, indicating its confrontation with nanoplastics-induced intestinal toxicity. To explore the ameliorative effects of maltol on polystyrene nanoplastics (PS)-mediated enterotoxicity and the underlying mechanism, the mice were exposed to PS (100 mg/kg), combining with or without the treatment of maltol treatment at 50 and 100 mg/kg. We found PS exposure caused intestinal barrier damage and enterocyte apoptosis, while lysosomal dysfunction and autophagic substrate degradation arrest in enterocytes of mice were also observed. In addition, PS exacerbated the disturbance of the intestinal microbial community, affected the abundance of lysosome and apoptosis-related bacterial genes, and decreased the number of known short-chain fatty acid (SCFA) producing bacteria. However, those alterations were improved by the maltol treatment. Maltol also protected the human intestinal Caco-2 cells from PS-induce damages. Mechanistic studies showed maltol promoted TFEB nuclear translocation through the AMPK/mTOR signaling pathway to restore lysosomal function and reduce autophagy dependent apoptosis. The findings in the present work might help to elucidate the potential molecular mechanisms of PS-induced enterotoxicity. For the first time to our knowledge, the protective effect of maltol on PS-induced intestinal injury was studied from multiple perspectives, which provided a potential therapeutic approach for diseases caused by environmental pollution.

Piwi maintains homeostasis in the Drosophila adult intestine.

PIWI genes are well known for their germline but not somatic functions. Here, we report the function of the Drosophila piwi gene in the adult gut, where intestinal stem cells (ISCs) produce enteroendocrine cells and enteroblasts that generate enterocytes. We show that piwi is expressed in ISCs and enteroblasts. Piwi deficiency reduced ISC number, compromised enteroblasts maintenance, and induced apoptosis in enterocytes, but did not affect ISC proliferation and its differentiation to enteroendocrine cells. In addition, deficiency of zygotic but not maternal piwi mildly de-silenced several retrotransposons in the adult gut. Importantly, either piwi mutations or piwi knockdown specifically in ISCs and enteroblasts shortened the Drosophila lifespan, indicating that intestinal piwi contributes to longevity. Finally, our mRNA sequencing data implied that Piwi may achieve its intestinal function by regulating diverse molecular processes involved in metabolism and oxidation-reduction reaction.

Symbiont coordinates stem cell proliferation, apoptosis, and morphogenesis of gut symbiotic organ in the stinkbug-Caballeronia symbiosis.

The bean bug Riptortus pedestris obtains a specific bacterial symbiont, Caballeronia insecticola (Burkholderia insecticola), from the environmental soil and harbors it in the posterior midgut region that is composed of hundreds of crypts. While newly hatched aposymbiotic insects possess primordial midgut crypts with little or no lumen, colonization of C. insecticola triggers swift development of the symbiotic organ, forming enlarged and opened crypts, and the symbiont subsequently fills the luminal cavities of those mature crypts. The cellular processes of crypt development triggered by C. insecticola colonization are poorly understood. Here we identified a fundamental mechanism of the symbiont-mediated midgut development by investigating cell cycles of intestinal epithelial cells. Intestinal stem cells of the bean bug are located and proliferate at the crypt base. Differentiated enterocytes migrate upward along the epithelial cell layer of the crypt as the midgut develops, induction of apoptosis in enterocytes primarily occurred on the tip side of the crypts, and apoptotic cells then eventually were shed from the crypts into the hemolymph. The proliferation rate of the stem cells at the base of the crypts was low while a high apoptotic rate was observed at the crypt tip in aposymbiotic insects, resulting in undeveloped short crypts. On the contrary, the gut-colonizing C. insecticola promoted the proliferation of the stem cells at the base of crypts and simultaneously inhibited apoptosis at the tip of crypts, resulting in a net growth of the crypts and the generation of a crypt lumen that becomes colonized by the bacterial symbiont. These results demonstrated that the Caballeronia symbiont colonization induces the development of the midgut crypts via finely regulating the enterocyte cell cycles, enabling it to stably and abundantly colonize the generated spacious crypts of the bean bug host.

DGAT1-ассоциированная белок-теряющая энтеропатия: первое описание клинического случая в России

DGAT1-associated protein-losing enteropathy is a rare autosomal recessive disorder related to congenital diarrhea and associated with a mutation in the DGAT1 gene that encodes the enzyme DGAT1, which is responsible for the final step of triglyceride resynthesis in enterocytes. With insufficient activity of DGAT1 enzyme, fatty acids and diacylglycerols accumulate in the enterocyte, having a cytotoxic effect and causing enterocyte apoptosis. As a result, atrophic enteropathy develops, which is manifested as protein-losing diarrhea from the first months of life, iron deficiency anemia, and vitamin D deficiency. The currently known treatment methods for DGAT1-associated enteropathy are a low-fat diet and parenteral nutrition. This article presents the first genetically confirmed clinical case of DGAT1-associated protein-losing enteropathy in the Russian Federation. Key words: DGAT1, enteropathy, congenital diarrhea, protein-losing diarrhea, children

Impaired FXR-CPT1a signaling contributes to parenteral nutrition-induced villus atrophy in short-bowel syndrome.

Parenteral nutrition (PN)-induced villus atrophy is a major cause of intestinal failure (IF) for children suffering from short bowel syndrome (SBS), but the precise mechanism remains unclear. Herein, we report a pivotal role of farnesoid X receptor (FXR) signaling and fatty acid oxidation (FAO) in PN-induced villus atrophy. A total of 14 pediatric SBS patients receiving PN were enrolled in this study. Those patients with IF showed longer PN duration and significant intestinal villus atrophy, characterized by remarkably increased enterocyte apoptosis concomitant with impaired FXR signaling and decreased FAO genes including carnitine palmitoyltransferase 1a (CPT1a). Likewise, similar changes were found in an in vivo model of neonatal Bama piglets receiving 14-day PN, including villus atrophy and particularly disturbed FAO process responding to impaired FXR signaling. Finally, in order to consolidate the role of the FXR-CPT1a axis in modulating enterocyte apoptosis, patient-derived organoids (PDOs) were used as a mini-gut model in vitro. Consequently, pharmacological inhibition of FXR by tauro-β-muricholic acid (T-βMCA) evidently suppressed CPT1a expression leading to reduced mitochondrial FAO function and inducible apoptosis. In conclusion, impaired FXR/CPT1a axis and disturbed FAO may play a pivotal role in PN-induced villus atrophy, contributing to intestinal failure in SBS patients.

ALDH2 deficiency increases susceptibility to binge alcohol-induced gut leakiness, endotoxemia, and acute liver injury in mice through the gut-liver axis

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is the major enzyme responsible for metabolizing toxic acetaldehyde to acetate and acts as a protective or defensive protein against various disease states associated with alcohol use disorder (AUD), including alcohol-related liver disease (ARLD). We hypothesized that Aldh2-knockout (KO) mice are more susceptible to binge alcohol-mediated liver injury than wild-type (WT) mice through increased oxidative stress, gut leakiness and endotoxemia. Therefore, this study aimed to investigate the protective role of ALDH2 in binge alcohol-induced gut permeability, endotoxemia, and acute inflammatory liver injury by exposing Aldh2-KO or WT mice to a single oral dose of binge alcohol 3.5, 4.0, or 5.0 g/kg. Our findings showed for the first time that ALDH2 deficiency in Aldh2-KO mice increases their sensitivity to binge alcohol-induced oxidative and nitrative stress, enterocyte apoptosis, and nitration of gut tight junction (TJ) and adherent junction (AJ) proteins, leading to their degradation. These resulted in gut leakiness and endotoxemia in Aldh2-KO mice after exposure to a single dose of ethanol even at 3.5 g/kg, while no changes were observed in the corresponding WT mice. The elevated serum endotoxin (lipopolysaccharide, LPS) and bacterial translocation contributed to systemic inflammation, hepatocyte apoptosis, and subsequently acute liver injury through the gut-liver axis. Treatment with Daidzin, an ALDH2 inhibitor, exacerbated ethanol-induced cell permeability and reduced TJ/AJ proteins in T84 human colon cells. These changes were reversed by Alda-1, an ALDH2 activator. Furthermore, CRISPR/Cas9-mediated knockout of ALDH2 in T84 cells increased alcohol-mediated cell damage and paracellular permeability. All these findings demonstrate the critical role of ALDH2 in alcohol-induced epithelial barrier dysfunction and suggest that ALDH2 deficiency or gene mutation in humans is a risk factor for alcohol-mediated gut and liver injury, and that ALDH2 could be an important therapeutic target against alcohol-associated tissue or organ damage.

Selective targeting of MD2 attenuates intestinal inflammation and prevents neonatal necrotizing enterocolitis by suppressing TLR4 signaling.

Neonatal necrotizing enterocolitis (NEC) is an inflammatory disease that occurs in premature infants and has a high mortality rate; however, the mechanisms behind this disease remain unclear. The TLR4 signaling pathway in intestinal epithelial cells, mediated by TLR4, is important for the activation of the inflammatory storm in NEC infants. Myeloid differentiation protein 2 (MD2) is a key auxiliary component of the TLR4 signaling pathway. In this study, MD2 was found to be significantly increased in intestinal tissues of NEC patients at the acute stage. We further confirmed that MD2 was upregulated in NEC rats. MD2 inhibitor (MI) pretreatment reduced the occurrence and severity of NEC in neonatal rats, inhibited the activation of NF-κB and the release of inflammatory molecules (TNF-α and IL-6), and reduced the severity of intestinal injury. MI pretreatment significantly reduced enterocyte apoptosis while also maintaining tight junction proteins, including occludin and claudin-1, and protecting intestinal mucosal permeability in NEC rats. In addition, an NEC in vitro model was established by stimulating IEC-6 enterocytes with LPS. MD2 overexpression in IEC-6 enterocytes significantly activated NF-κB. Further, both MD2 silencing and MI pretreatment inhibited the inflammatory response. Overexpression of MD2 increased damage to the IEC-6 monolayer cell barrier, while both MD2 silencing and MI pretreatment played a protective role. In conclusion, MD2 triggers an inflammatory response through the TLR4 signaling pathway, leading to intestinal mucosal injury in NEC. In addition, MI alleviates inflammation and reduces intestinal mucosal injury caused by the inflammatory response by blocking the TLR4-MD2/NF-κB signaling axis. These results suggest that inhibiting MD2 may be an important way to prevent NEC.