Alcohol-induced IL-17A production in Paneth cells amplifies endoplasmic reticulum stress, apoptosis, and inflammasome-IL-18 activation in the proximal small intestine in mice

Heat stress induces calcium dyshomeostasis to subsequent cognitive impairment through ERS-mediated apoptosis via SERCA/PERK/eIF2α pathway

Heat exposure is an environmental stressor that has been associated with cognitive impairment. However, the neural mechanisms that underlie this phenomenon have yet to be extensively investigated. The Morris water maze test was utilized to assess cognitive performance. RNA sequencing was employed to discover the primary regulators and pathological pathways involved in cognitive impairment caused by heat. Before heat exposure in vivo and in vitro, activation of the sarco/endoplasmic reticulum (SR/ER) calcium (Ca2+)-ATPase (SERCA) was achieved by CDN1163. Hematoxylin-Eosin, Nissl staining, calcium imaging, transmission electron microscopy, western blot, and immunofluorescence were utilized to visualize histological changes, intracellular calcium levels, endoplasmic reticulum stress (ERS) markers, apoptosis, and synaptic proteins alterations. Heat stress (HS) significantly induced cognitive decline and neuronal damage in mice. By the transcriptome sequencing between control (n = 5) and heat stress (n = 5) mice in hippocampal tissues, we identified a reduction in the expression of the atp2a gene encoding SERCA, accompanied by a corresponding decrease in its protein level. Consequently, this dysregulation resulted in an excessive accumulation of intracellular calcium ions. Furthermore, HS exposure also activated ERS and apoptosis, as evidenced by the upregulation of p-PERK, p-eIF2α, CHOP, and caspase-3. Consistently, a reduction in postsynaptic density protein 95 (PSD95) and synaptophysin (SYN) expressions indicated modifications in synaptic function. Notably, the impacts on neurons caused by HS were found to be mitigated by CDN1163 treatment both in vivo and in vitro. Additionally, SERCA-mediated ERS-induced apoptosis was attenuated by GSK2606414 treatment via inhibiting PERK-eIF2α-CHOP axis that not only curtailed the level of caspase-3 but also elevated the levels of PSD95 and SYN. These findings highlight the significant impact of heat stress on cognitive impairment, and further elucidate the underlying mechanism involving SERCA/PERK/eIF2α pathway.

Spatial Proteomics Reveals Alcohol-Induced Damages to the Crypts and Villi of the Mouse Small Intestine

Alcohol consumption perturbs the gut immune barrier and ultimately results in alcoholic liver diseases, but little is known about how immune-related cells in the gut are perturbed in this process. In this study, we employed laser capture microdissection and a label-free proteomics approach to investigate the consequences of alcohol exposure to the proteomes of crypts and villi in the proximal small intestine. Intestinal tissues from alcohol-fed and pair-fed mice were microdissected to selectively capture cells in the crypts and villi regions, followed by one-pot protein digestion and data-independent LC-MS/MS analysis. We successfully identified over 3000 proteins from each of the crypt or villi regions equivalent to ∼3000 cells. Analysis of alcohol-treated tissues indicated an enhanced alcohol metabolism and reduced levels of α-defensins in crypts, alongside increased lipid metabolism and apoptosis in villi. Immunofluorescence imaging further corroborated the proteomic findings. Our work provides a detailed profiling of the proteomic changes in the compartments of the mouse small intestine and aids in molecular-level understanding of alcohol-induced tissue damage.

Gut-liver axis: Recent concepts in pathophysiology in alcohol-associated liver disease

The growing recognition of the role of the gut microbiome's impact on alcohol-associated diseases, especially in alcohol-associated liver disease, emphasizes the need to understand molecular mechanisms involved in governing organ-organ communication to identify novel avenues to combat alcohol-associated diseases. The gut-liver axis refers to the bidirectional communication and interaction between the gut and the liver. Intestinal microbiota plays a pivotal role in maintaining homeostasis within the gut-liver axis, and this axis plays a significant role in alcohol-associated liver disease. The intricate communication between intestine and liver involves communication between multiple cellular components in each organ that enable them to carry out their physiological functions. In this review, we focus on novel approaches to understanding how chronic alcohol exposure impacts the microbiome and individual cells within the liver and intestine, as well as the impact of ethanol on the molecular machinery required for intraorgan and interorgan communication.

Paneth cell: The missing link between obesity, MASH and portal hypertension

Obesity is a global health crisis, with its prevalence steadily rising over the past few decades. One concerning consequence of obesity is its association with metabolic associated steatohepatitis [MASH], portal hypertension and liver cirrhosis. Cirrhosis is irreversible, but stages of liver disease before the development of cirrhosis are reversible with appropriate interventions. Studies have brought into light new entities that influences the pathophysiology of portal hypertension. This review provides evidence supporting that, Paneth cells[PCs] in the intestinal epithelium, which remained enigmatic for a century, are the maneuverer of pathophysiology of portal hypertension and obesity. PC dysfunction can cause perturbation of the intestinal microbiota and changes in intestinal permeability, which are the potential triggers of systemic inflammation. Thus, it can offer unique opportunities to understand the pathophysiology of portal hypertension for intervention strategies.

The Dynamic Role of Endoplasmic Reticulum Stress in Chronic Liver Disease

Chronic liver disease (CLD) is a major worldwide public health threat, with an estimated prevalence of 1.5 billion individuals with CLD in 2020. Chronic activation of endoplasmic reticulum (ER) stress-related pathways is recognized as substantially contributing to the pathologic progression of CLD. The ER is an intracellular organelle that folds proteins into their correct three-dimensional shapes. ER-associated enzymes and chaperone proteins highly regulate this process. Perturbations in protein folding lead to misfolded or unfolded protein accumulation in the ER lumen, resulting in ER stress and concomitant activation of the unfolded protein response (UPR). The adaptive UPR is a set of signal transduction pathways evolved in mammalian cells that attempts to reestablish ER protein homeostasis by reducing protein load and increasing ER-associated degradation. However, maladaptive UPR responses in CLD occur due to prolonged UPR activation, leading to concomitant inflammation and cell death. This review assesses the current understanding of the cellular and molecular mechanisms that regulate ER stress and the UPR in the progression of various liver diseases and the potential pharmacologic and biological interventions that target the UPR.

Advanced oxidation protein products induce Paneth cells defects by endoplasmic reticulum stress in Crohn's disease

Paneth cells (PC) play a key role in the innate immune response of intestine epithelium, and PC defects contribute to the pathogenesis of Crohn's disease (CD). In this study, we utilized active CD tissues and advanced oxidation protein products (AOPP)-challenged C57BL/6 mouse model to investigate the effect of AOPP on PC defects in CD. We found that AOPP accumulated in active CD tissues and was negatively associated with lysozyme expression, while positively correlated with the presence of ER stress markers. Furthermore, AOPP treatment induced PC defects mainly through excessive ER stress in vivo, and AOPP also caused mitochondria-associated ER membranes formation and mitochondrial dysfunction. In addition, the effects of AOPP could be attenuated by the administration of ER stress inhibitor, TUDCA. These findings suggest a pathogenic role of AOPP contributing to PC defects and may provide the basis for developing new strategies to managing CD.

Effects of dietary irritants on intestinal homeostasis and the intervention strategies

Abundant diet components are unexplored as vital factors in intestinal homeostasis. Dietary irritants stimulate the nervous system and provoke somatosensory responses, further inducing diarrhea, gut microbiota disorder, intestinal barrier damage or even severe gastrointestinal disease. We depicted the effects of food with piquancy, high fat, low pH, high-refined carbohydrates, and indigestible texture. The mechanism of dietary irritants on intestinal homeostasis were comprehensively summarized. Somatosensory responses to dietary irritants are palpable and have specific chemical and neural mechanisms. In contrast, even low-dose exposure to dietary irritants can involve multiple intestinal barriers. Their mechanisms in intestinal homeostasis are often overlapping and dose-dependent. Therefore, treating symptoms caused by dietary irritants requires personalized nutritional advice. The reprocessing of stimulant foods, additional supplementation with probiotics or prebiotics, and enhancement of the intestinal barrier are effective intervention strategies. This review provides promising preliminary guidelines for the treatment of symptoms and gastrointestinal injury caused by dietary irritants.

Paneth cell development in the neonatal gut: pathway regulation, development, and relevance to necrotizing enterocolitis

Paneth cells (PCs) are intestinal epithelial cells (IECs) that contain eosinophilic granules, which are located in Lieberkühn crypts. An increasing number of animal and human experiments have indicated that PCs are involved in the progression of a variety of intestinal as well as systemic inflammatory responses including necrotizing enterocolitis (NEC). NEC is an enteric acquired disease with high mortality that usually occurs in premature infants and neonates, however the underlying mechanisms remain unclear. In this review, we summarize the features of PCs, including their immune function, association with gut microbiota and intestinal stem cells, and their mechanism of regulating IEC death to explore the possible mechanisms by which PCs affect NEC.

Heat Stress-Induced Intestinal Barrier Impairment: Current Insights into the Aspects of Oxidative Stress and Endoplasmic Reticulum Stress

Heat stress (HS) occurs when the sensible temperature of animals exceeds their thermoregulatory capacity, a condition that exerts a detrimental impact on health and growth. The intestinal tract, as a highly sensitive organ, has been shown to respond to HS by exhibiting mucosal injury, intestinal leakage, and disturbances in the gut microbiota. Oxidative stress and endoplasmic reticulum stress (ERS) are both potential outcomes of long-term exposure to high temperatures and have been linked to apoptosis, autophagy, and ferroptosis. In addition, HS alters the composition of the gut microbiota accompanied by changed levels of bacterial components and metabolites, rendering the gut more vulnerable to stress-related injury. In this review, we present recent advances in mechanisms of oxidative stress-associated ERS in response to HS, which is destructive to intestinal barrier integrity. The involvement of autophagy and ferroptosis in ERS was highlighted. Further, we summarize the relevant findings regarding the engagement of gut microbiota-derived components and metabolites in modulation of intestinal mucosal injury induced by HS.

Multifaceted involvements of Paneth cells in various diseases within intestine and systemically

Serving as the guardians of small intestine, Paneth cells (PCs) play an important role in intestinal homeostasis maintenance. Although PCs uniquely exist in intestine under homeostasis, the dysfunction of PCs is involved in various diseases not only in intestine but also in extraintestinal organs, suggesting the systemic importance of PCs. The mechanisms under the participation of PCs in these diseases are multiple as well. The involvements of PCs are mostly characterized by limiting intestinal bacterial translocation in necrotizing enterocolitis, liver disease, acute pancreatitis and graft-vs-host disease. Risk genes in PCs render intestine susceptible to Crohn’s disease. In intestinal infection, different pathogens induce varied responses in PCs, and toll-like receptor ligands on bacterial surface trigger the degranulation of PCs. The increased level of bile acid dramatically impairs PCs in obesity. PCs can inhibit virus entry and promote intestinal regeneration to alleviate COVID-19. On the contrary, abundant IL-17A in PCs aggravates multi-organ injury in ischemia/reperfusion. The pro-angiogenic effect of PCs aggravates the severity of portal hypertension. Therapeutic strategies targeting PCs mainly include PC protection, PC-derived inflammatory cytokine elimination, and substituting AMP treatment. In this review, we discuss the influence and importance of Paneth cells in both intestinal and extraintestinal diseases as reported so far, as well as the potential therapeutic strategies targeting PCs.

Therapeutic Perspectives of IL1 Family Members in Liver Diseases: An Update

Interleukin (IL) 1 superfamily members are a cornerstone of a variety of inflammatory processes occurring in various organs including the liver. Progression of acute and chronic liver diseases regardless of etiology depends on the stage of hepatocyte damage, the release of inflammatory cytokines and disturbances in gut microbiota. IL1 cytokines and receptors can have pro- or anti-inflammatory roles, even dual functionalities conditioned by the microenvironment. Developing novel therapeutic strategies to block the IL1/IL1R signaling pathways seems like a reasonable option. This mode of action is now exploited by anakinra and canakinumab, which are used to treat different inflammatory illnesses, and studies in liver diseases are on the way. In this mini review, we have focused on the IL1 superfamily members, given their crucial role in liver inflammation diseases, specifically discussing their potential role in developing new treatment strategies.

Paneth cells as the cornerstones of intestinal and organismal health: a primer

Paneth cells are versatile secretory cells located in the crypts of Lieberkühn of the small intestine. In normal conditions, they function as the cornerstones of intestinal health by preserving homeostasis. They perform this function by providing niche factors to the intestinal stem cell compartment, regulating the composition of the microbiome through the production and secretion of antimicrobial peptides, performing phagocytosis and efferocytosis, taking up heavy metals, and preserving barrier integrity. Disturbances in one or more of these functions can lead to intestinal as well as systemic inflammatory and infectious diseases. This review discusses the multiple functions of Paneth cells, and the mechanisms and consequences of Paneth cell dysfunction. It also provides an overview of the tools available for studying Paneth cells.

Effects of the Gut Microbiota and Barrier Function on Melatonin Efficacy in Alleviating Liver Injury

Environmental cadmium (Cd) exposure has been associated with severe liver injury. In contrast, melatonin (Mel) is a candidate drug therapy for Cd-induced liver injury due to its diverse hepatoprotective activities. However, the precise molecular mechanism by which Mel alleviates the Cd-induced liver injury, as well as the Mel–gut microbiota interaction in liver health, remains unknown. In this study, mice were given oral gavage CdCl2 and Mel for 10 weeks before the collection of liver tissues and colonic contents. The role of the gut microbiota in Mel’s efficacy in alleviating the Cd-induced liver injury was evaluated by the gut microbiota depletion technique in the presence of antibiotic treatment and gut microbiota transplantation (GMT). Our results revealed that the oral administration of Mel supplementation mitigated liver inflammation, endoplasmic reticulum (ER) stress and mitophagy, improved the oxidation of fatty acids, and counteracted intestinal microbial dysbiosis in mice suffering from liver injury. It was interesting to find that neither Mel nor Cd administration induced any changes in the liver of antibiotic-treated mice. By adopting the GMT approach where gut microbiota collected from mice in the control (CON), Cd, or Mel + Cd treatment groups was colonized in mice, it was found that gut microbiota was involved in Cd-induced liver injury. Therefore, the gut microbiota is involved in the Mel-mediated mitigation of ER stress, liver inflammation and mitophagy, and the improved oxidation of fatty acids in mice suffering from Cd-induced liver injury.

Trehalose Attenuates Oxidative Stress and Endoplasmic Reticulum Stress-Mediated Apoptosis in IPEC-J2 Cells Subjected to Heat Stress

This study was carried out to investigate the effects of trehalose (Tre) on antioxidant capacity, endoplasmic reticulum stress (ERS) response and apoptosis of heat-stressed intestinal porcine epithelial cells (IPEC-J2). IPEC-J2 cells were cultured at 37 °C until the end of the experiment (control, CON); exposed to heat stress for 2 h (43 °C, HS); or pretreated with 0.1, 1, 5, 10, and 15 mM trehalose at 37 °C for 4 h prior to heat stress exposure for 2 h. The optimum level of trehalose for protecting against HS-induced cell injuries was determined to be 10 mM, as evidenced by the highest cellular viability and lowest malondialdehyde (MDA) content and lactate dehydrogenase (LDH) activity. Based on these, IPEC-J2 cells were divided into three groups: the first group was cultured at 37 °C until the end of the experiment (control, CON); the second group was exposed to heat stress for 2 h (43 °C, HS); the third group was pretreated with 10 mM trehalose for 4 h at 37 °C prior to heat stress exposure for 2 h (Tre + HS). The reactive oxygen species (ROS) content, superoxide dismutase (SOD) activity, mitochondrial membrane potential (MMP) changes, and expressions of the manganese superoxide dismutase (SOD2), ERS and apoptosis-related proteins were determined. Compared to the CON group, HS significantly increased ROS generation (p < 0.01), decreased SOD activity (p < 0.05), and downregulated protein expression of SOD2 (p < 0.01). Compared to the HS group, Tre supplementation reduced ROS levels and increased SOD activity and SOD2 expression to the levels that were comparable to the control (p < 0.05). The HS-induced ERS response was evidenced by the increased protein expressions of glucose-regulated protein 78 (GRP78) (p < 0.01), eukaryotic translation initiation factor 2α (p-eif2α) (p < 0.01), transcription activator 4 (ATF4) (p < 0.01), and the protein expression of C/EBP homologous protein (CHOP) (p < 0.01), which were the four hallmarks of ERS. The Tre + HS group showed lower expressions of GRP78 (p < 0.01), p-eif2α (p < 0.01), ATF4 (p < 0.01), and CHOP (p < 0.01) than that of the HS group. Tre pretreatment attenuated HS-induced mitochondrial apoptosis in IPEC-J2 cells, demonstrated by the increased MMP and decreased proapoptotic proteins active caspase 3, Bax, and cytochrome c (Cyt c). Taken together, trehalose can protect against HS-induced oxidative damage and endoplasmic reticulum stress-mediated apoptosis in IPEC-J2 cells. These data may provide a nutritional strategy for alleviating heat stress in pig production.

Akkermansia muciniphila Colonization Alleviating High Fructose and Restraint Stress-Induced Jejunal Mucosal Barrier Disruption

Akkermansia muciniphila (A. muciniphila) is a mucin-degrading bacterium that resides in the mucus layer, but its potential in intestinal inflammatory diseases has sparked controversy. It is well known that both the consumption of fructose-containing beverages and psychological stress increase the risk of intestinal disease. Our results revealed that a high-fructose diet aggravated the damage to the jejunal mucosal barrier caused by restraint stress, reduced tight junction protein expression and the intestinal digestion and absorption capacity, disrupted the ability of Paneth cells to secrete antimicrobial peptides, and promoted the expression of inflammatory cytokines. A. muciniphila colonization enhanced the defense function of the mucosal barrier by enhancing the function of the NLRP6, promoting autophagy, maintaining the normal secretion of antimicrobial peptides in Paneth cells, promoting the expression of tight junction proteins, negatively regulating the NF-kB signaling pathway and inhibiting the expression of inflammatory cytokines. Our work indicates that A. muciniphila ameliorates the disruption of the intestinal mucosal barrier under high fructose and restraint stress. These results provided a rationale for the development of probiotic colonization for the prevention or treatment of intestinal diseases.

Gut microbiota dysbiosis: The potential mechanisms by which alcohol disrupts gut and brain functions

Alcohol use disorder (AUD) is a high-risk psychiatric disorder and a key cause of death and disability in individuals. In the development of AUD, there is a connection known as the microbiota-gut-brain axis, where alcohol use disrupts the gut barrier, resulting in changes in intestinal permeability as well as the gut microbiota composition, which in turn impairs brain function and worsens the patient’s mental status and gut activity. Potential mechanisms are explored by which alcohol alters gut and brain function through the effects of the gut microbiota and their metabolites on immune and inflammatory pathways. Alcohol and microbiota dysregulation regulating neurotransmitter release, including DA, 5-HT, and GABA, are also discussed. Thus, based on the above discussion, it is possible to speculate on the gut microbiota as an underlying target for the treatment of diseases associated with alcohol addiction. This review will focus more on how alcohol and gut microbiota affect the structure and function of the gut and brain, specific changes in the composition of the gut microbiota, and some measures to mitigate the changes caused by alcohol exposure. This leads to a potential intervention for alcohol addiction through fecal microbiota transplantation, which could normalize the disruption of gut microbiota after AUD.

Role of the Inflammasome in Liver Disease

The involvement of inflammasomes in the proinflammatory response observed in chronic liver diseases, such as alcohol-associated liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD), is widely recognized. Although there are different types of inflammasomes, most studies to date have given attention to NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3) in the pathogenesis of ALD, NAFLD/nonalcoholic steatohepatitis, and fibrosis. Canonical inflammasomes are intracellular multiprotein complexes that are assembled after the sensing of danger signals and activate caspase-1, which matures interleukin (IL)-1β, IL-18, and IL-37 and also induces a form of cell death called pyroptosis. Noncanonical inflammasomes activate caspase-11 to induce pyroptosis. We discuss the different types of inflammasomes involved in liver diseases with a focus on (a) signals and mechanisms of inflammasome activation, (b) the role of different types of inflammasomes and their products in the pathogenesis of liver diseases, and (c) potential therapeutic strategies targeting components of the inflammasomes or cytokines produced upon inflammasome activation.

Crosstalk between Endoplasmic Reticulum Stress and Oxidative Stress in Heat Exposure-Induced Apoptosis Is Dependent on the ATF4-CHOP-CHAC1 Signal Pathway in IPEC-J2 Cells

The intestinal epithelium is susceptible to heat stress (HS), which leads to gut leakage and inflammation. However, the mechanisms underlying HS-induced intestine dysfunction have yet to be elucidated. We established an in vitro chronic heat exposure-induced intestinal injury of intestinal porcine epithelial cells (IPEC-J2) exposed to high temperatures (43 °C) for 12 h. The results revealed that HS increased reactive oxygen species (ROS) generation and decreased superoxide dismutase 2 (SOD2) expression, leading to oxidative stress. Western blotting analysis demonstrated that HS induced apoptosis as evidenced by increased cytochrome c (Cyt c) release in the cytoplasm and caspase 3 activation. Transcriptome sequencing analysis revealed that HS activated the endoplasmic reticulum stress (ERS) response/unfolded protein response (UPR) but inhibited glutathione metabolism. Specifically, HS triggered the pro-apoptotic activating transcription factor 4 (ATF4)/CEBP-homologous protein (CHOP) branch of the UPR. Interestingly, glutathione-specific gamma-glutamylcyclotransferase1 (CHAC1) involved in glutathione degradation was upregulated due to heat exposure and was proved to be downstream of the ATF4-CHOP signal pathway. Knockdown of CHAC1 attenuated the HS-induced decrease in glutathione level and cell apoptosis. These studies suggest that crosstalk between ERS and oxidative stress in HS-induced apoptosis might be dependent on the ATF4-CHOP-CHAC1 signal pathway in IPEC-J2 cells.

CCAAT/Enhancer-Binding Protein Homologous Protein (CHOP) Deficiency Attenuates Heatstroke-Induced Intestinal Injury

The intestine is one of the main target organs involved in the pathological process of heatstroke. CCAAT/enhancer-binding protein homologous protein (CHOP) is involved in endoplasmic reticulum (ER) stress-induced apoptosis. This study aimed to explore the role of CHOP in heatstroke-induced intestinal injury and potential therapy. An in vitro heat stress (HS) model using Caco-2 cells was employed. We observed the role of CHOP in apoptosis-mediated intestinal epithelial cell injury secondary to HS by evaluating cell viability, lactate dehydrogenase release, apoptosis levels, and GRP78, PERK, ATF4, CHOP, Bcl-2, and BAX mRNA and protein expression. To further study the role of CHOP in HS-induced intestinal barrier dysfunction, we assessed transepithelial electrical resistance, paracellular tracer flux, ultrastructure of tight junctions, and protein expression of ZO-1 and occludin. Male wild-type mice and CHOP knockout mice were used for in vivo experiments. We evaluated serum d-lactate and diamine oxidase levels, histopathological changes, intestinal ultrastructure, and ZO-1 and occludin protein expression. HS activated the PERK-CHOP pathway and promoted apoptosis by upregulating BAX and downregulating Bcl-2; these effects were prevented by CHOP silencing. Intestinal epithelial barrier function was disrupted by HS in vitro and in vivo. CHOP silencing prevented intestinal barrier dysfunction in Caco-2 cells, whereas CHOP knockout mice exhibited decreased intestinal mucosal injury. The ER stress inhibitor 4-phenylbutyrate (4-PBA) prevented HS-induced intestinal injury in vitro and in vivo. This study indicated that CHOP deficiency attenuates heatstroke-induced intestinal injury and may contribute to the identification of a novel therapy against heatstroke associated with the ER stress pathway.

Heat stress induced IPEC-J2 cells barrier dysfunction through endoplasmic reticulum stress mediated apoptosis by p-eif2α/CHOP pathway

Heat stress (HS) induced by high ambient temperatures compromises intestinal epithelial cell. However, the underlying mechanisms by which HS causes intestinal barrier dysfunction remain unclear. In this study, we established an in vitro acute-HS-induced intestinal damage using porcine small intestinal epithelial cell (IPEC-J2) that exposed to the high temperatures (43°C) for 2 h. The cell proliferation, apoptosis, tight junction (TJ) barrier integrity and transcriptomic profiles were measured. The results showed that HS decreased cell viability while increased proapoptotic signaling evidenced by Bax/bcl2 ratio, cytochrome C release to cytosol and active-caspase 3 increases (p < 0.01). HS led to decreased transepithelial electrical resistance, increased cell permeability, and downregulated TJ proteins including ZO1, occludin, and claudin 3 (p < 0.05). Transcriptome sequencing and KEGG pathway analysis revealed HS-induced cell cycle arrest and activation of endoplasmic reticulum stress (ERS) response mediated by a critical transcript eif2α and proapoptotic molecule DDIT3 (known as CHOP). Furthermore, inhibition of ERS by 4-phenylbutyrate (4-PBA) administration and knockdown of eif2α and CHOP significantly attenuated IPEC-J2 cells apoptosis (p < 0.05). Transmission electron microscopy analysis suggested that 4-PBA inhibited HS-induced increase in ER lumen diameter, indicating ultrastructural sign of ERS. In addition, HS-induced impairment of TJs was significantly attenuated by 4-PBA (p < 0.05). Collectively, HS induces ERS and activates the p-eif2α/CHOP signaling pathway to impair epithelial barrier integrity through triggering the intestinal epithelial cell apoptosis.

Selenium deficiency causes apoptosis through endoplasmic reticulum stress in swine small intestine

Selenium (Se) plays a crucial role in intestinal health. However, the specific mechanism by which deficiency of Se causes intestinal damage remains unclear. This study was to explore whether Se deficiency can cause ER stress and induce apoptosis in swine small intestine. We established the Se deficiency swine model in vivo and the intestinal epithelial (IPEC-J2) cell Se deficiency model in vitro. The results of morphological observation showed that Se deficiency caused structural damage in intestinal villi and the decrease of goblet cell structure. The apoptotic characteristics such as nucleolar condensation, mitochondrial swelling, and apoptotic bodies were observed in the IPEC-J2 cells. The results of acridine orange/ethidium bromide and mitochondrial membrane potential fluorescence staining in vitro showed that there were more apoptotic cells in the Se-deficiency group than that in the control group. The protein and/or mRNA expression levels of Bax, Bcl-2, caspase 3, caspase 8, caspase 9, cytc, PERK, ATF6, IRE, XBP1, CHOP, GRP78, which are related to ER stress-apoptosis pathway, were significantly increased in the Se-deficient group which compared with the control group in vivo and in vitro were consistent. These results indicated that Se deficiency induced ER stress and increased the apoptosis in swine small intestine and IPEC-J2 cells and then caused the damage in swine small intestinal tissue. Besides, the results of gene expressions in our experiment proved that ER stress induced by Se deficiency promoted apoptosis. These results filled the blank in the mechanism of Se deficiency-induced intestinal injury in swine.

Immune Response to an Acute Moderate Dose of Alcohol in Healthy Young Adults

Prior research on alcohol and the immune system has tended to focus on binge doses or chronic heavy drinking. The aim of this single-session preliminary study was to characterize immune response to moderate alcohol (0.60 g alcohol per kilogram body weight) in healthy, nonchronic drinkers. The sample (N = 11) averaged 26.6 years of age and was balanced in gender. Plasma samples were collected at baseline and 1, 2 and 3 hours postconsumption. Markers of microbial translocation [lipopolysaccharide (LPS)] and innate immune response [LPS-binding protein (LBP), soluble cluster of differentiation 14 (sCD14), and selected cytokines] were measured using immunoassays. Participants completed self-report questionnaires on subjective alcohol response and craving. Linear mixed models were used to assess changes in biomarkers and self-report measures. Breath alcohol concentration peaked at 0.069 ± 0.008% 1 hour postconsumption. LPS showed a significant linear decrease. LBP and sCD14 showed significant, nonlinear (U-shaped) trajectories wherein levels decreased at 1 hour then rebounded by 3 hours. Of nine cytokines tested, only MCP-1 and IL-8 were detectable in ≥50% of samples. IL-8 did not change significantly. MCP-1 showed a significant linear decrease and also accounted for significant variance in alcohol craving, with higher levels associated with stronger craving. Results offer novel evidence on acute immune response to moderate alcohol. Changes in LBP and sCD14, relative to LPS, may reflect their role in LPS clearance. Results also support further investigation into the role of MCP-1 in alcohol craving. Limitations include small sample size and lack of a placebo condition.

Secretory Sorcery: Paneth Cell Control of Intestinal Repair and Homeostasis

Paneth cells are professional secretory cells that classically play a role in the innate immune system by secreting antimicrobial factors into the lumen to control enteric bacteria. In this role, Paneth cells are able to sense cues from luminal bacteria and respond by changing production of these factors to protect the epithelial barrier. Paneth cells rely on autophagy to regulate their secretory capability and capacity. Disruption of this pathway through mutation of genes, such as Atg16L1, results in decreased Paneth cell function, dysregulated enteric microbiota, decreased barrier integrity, and increased risk of diseases such as Crohn's disease in humans. Upon differentiation Paneth cells migrate downward and intercalate among active intestinal stem cells at the base of small intestinal crypts. This localization puts them in a unique position to interact with active intestinal stem cells, and recent work shows that Paneth cells play a critical role in influencing the intestinal stem cell niche. This review discusses the numerous ways Paneth cells can influence intestinal stem cells and their niche. We also highlight the ways in which Paneth cells can alter cells and other organ systems.

Blocking the interaction between interleukin-17A and endoplasmic reticulum stress in macrophage attenuates retinal neovascularization in oxygen-induced retinopathy

BACKGROUND

Neovascularization is a leading cause of visual loss typically associated with diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Interleukin-17A (IL-17A) and endoplasmic reticulum (ER) stress both have been demonstrated to play a proangiogenic role in ischemic retinopathies. However, the relationship between IL-17A and ER stress in retinal neovascularization (RNV) under hypoxic conditions and its underlying mechanisms remain unclear.

METHODS

In this study, oxygen-induced retinopathy (OIR) mice model was established and intravitreal injections were conducted. Changes of IL-17A and ER stress markers in retinas and cultured primary bone marrow derived macrophage (BMDM) under normoxic or hypoxic conditions were detected. Western blotting, Real-Time RT-PCR, Immunofluorescence assays were conducted to explore the roles and relationship of IL-17A and ER stress in RNV, as well as its underlying mechanisms.

RESULTS

Compared to that in normal controls, IL-17A and ER stress markers were all remarkably increased under hypoxic conditions both in vivo and in vitro. Neutralization or knock out of IL-17A decreased ER stress. ER stress inhibitor 4-phenylbutyrate (4-PBA), attenuated the production of IL-17A, suggesting a positive feedback loop between IL-17A and ER stress. Inhibition of IL-17A or ER stress decreased areas of nonperfusion and neovascularization in OIR retinas. As TXNIP/NLRP3 pathway activation has been demonstrated to be involved in increased retinal vascular permeability of ischemic retinopathy, we observed that TXNIP/NLRP3 pathway mediated in the interaction between IL-17A and ER stress under hypoxic conditions.

CONCLUSION

The interplay between IL-17A and ER stress contributes to RNV in macrophages via modulation of TXNIP/NLRP3 signaling pathway under hypoxic conditions. The feedback loops may become an innovative and multiple pharmacological therapeutic target for ischemic retinopathy.

Translational Approaches with Antioxidant Phytochemicals against Alcohol-Mediated Oxidative Stress, Gut Dysbiosis, Intestinal Barrier Dysfunction, and Fatty Liver Disease

Emerging data demonstrate the important roles of altered gut microbiomes (dysbiosis) in many disease states in the peripheral tissues and the central nervous system. Gut dysbiosis with decreased ratios of Bacteroidetes/Firmicutes and other changes are reported to be caused by many disease states and various environmental factors, such as ethanol (e.g., alcohol drinking), Western-style high-fat diets, high fructose, etc. It is also caused by genetic factors, including genetic polymorphisms and epigenetic changes in different individuals. Gut dysbiosis, impaired intestinal barrier function, and elevated serum endotoxin levels can be observed in human patients and/or experimental rodent models exposed to these factors or with certain disease states. However, gut dysbiosis and leaky gut can be normalized through lifestyle alterations such as increased consumption of healthy diets with various fruits and vegetables containing many different kinds of antioxidant phytochemicals. In this review, we describe the mechanisms of gut dysbiosis, leaky gut, endotoxemia, and fatty liver disease with a specific focus on the alcohol-associated pathways. We also mention translational approaches by discussing the benefits of many antioxidant phytochemicals and/or their metabolites against alcohol-mediated oxidative stress, gut dysbiosis, intestinal barrier dysfunction, and fatty liver disease.

Inhibition of Sphingosine-1-Phosphate-Induced Th17 Cells Ameliorates Alcohol-Associated Steatohepatitis in Mice

BACKGROUND AND AIMS

Chronic alcohol consumption is accompanied by intestinal inflammation. However, little is known about how alterations to the intestinal immune system and sphingolipids contribute to the pathogenesis of alcohol-associated liver disease (ALD).

APPROACH AND RESULTS

We used wild-type mice, retinoid-related orphan receptor gamma t (RORγt)-deficient mice, sphingosine kinase-deficient mice, and local gut anti-inflammatory, 5-aminosalicyclic acid-treated mice in a chronic-binge ethanol feeding model. Targeted lipidomics assessed the sphingolipids in gut and liver samples. Gut immune cell populations, the amounts of sphingolipids, and the level of liver injury were examined. Alcohol intake induces a pro-inflammatory shift in immune cell populations in the gut, including an increase in Th17 cells. Using RORγt-deficient mice, we found that Th17 cells are required for alcohol-associated gut inflammation and the development of ALD. Treatment with 5-aminosalicyclic acid decreases alcohol-induced liver injury and reverses gut inflammation by the suppression of CD4⁺ /RORγt⁺ /interleukin-17A⁺ cells. Increased Th17 cells were due to up-regulation of sphingosine kinase 1 activity and RORγt activation. We found that S1P/S1PR1 signaling is required for the development of Th17 cell-mediated ALD. Importantly, in vivo intervention blocking of S1P/S1PR1 signaling markedly attenuated alcohol-induced liver inflammation, steatosis, and damage.

CONCLUSIONS

Gut inflammation is a functional alteration of immune cells in ALD. Reducing gut Th17 cells leads to reduced liver damage. S1P signaling was crucial in the pathogenesis of ALD in a Th17 cell-dependent manner. Furthermore, our findings suggest that compounds that reduce gut inflammation locally may represent a unique targeted approach in the treatment of ALD.

A Perspective Of Intestinal Immune-Microbiome Interactions In Alcohol-Associated Liver Disease

Uncovering the intricacies of the gut microbiome and how it interacts with the host immune system has opened up pathways in the search for the treatment of disease conditions. Alcohol-associated liver disease is a major cause of death worldwide. Research has shed light on the breakdown of the protective gut barriers, translocation of gut microbes to the liver and inflammatory immune response to microbes all contributing to alcohol-associated liver disease. This knowledge has opened up avenues for alternative therapies to alleviate alcohol-associated liver disease based on the interaction of the commensal gut microbiome as a key player in the regulation of the immune response. This review describes the relevance of the intestinal immune system, the gut microbiota, and specialized and non-specialized intestinal cells in the regulation of intestinal homeostasis. It also reflects how these components are altered during alcohol-associated liver disease and discusses new approaches for potential future therapies in alcohol-associated liver disease.

Transcriptomic Profiling Identifies Novel Hepatic and Intestinal Genes Following Chronic Plus Binge Ethanol Feeding in Mice

BACKGROUND

Alcohol-associated liver disease accounts for half of cirrhosis-related deaths worldwide. The spectrum of disease varies from simple steatosis to fibrosis, cirrhosis and ultimately hepatocellular carcinoma. Understanding the disease on a molecular level helps us to develop therapeutic targets.

AIM

We performed transcriptomic analysis in liver and ileum from chronic plus binge ethanol-fed mice, and we assessed the role of selected differentially expressed genes and their association with serum bile acids and gut microbiota.

METHODS

Wild-type mice were subjected to a chronic Lieber-DeCarli diet model for 8 weeks followed by one binge of ethanol. RNA-seq analysis was performed on liver and ileum samples. Associations between selected differentially regulated genes and serum bile acid profile or fecal bacterial profiling (16S rDNA sequencing) were investigated.

RESULTS

We provide a comprehensive transcriptomic analysis to identify differentially expressed genes, KEGG pathways, and gene ontology functions in liver and ileum from chronic plus binge ethanol-fed mice. In liver, we identified solute carrier organic anion transporter family, member 1a1 (Slco1a1; encoding for organic anion transporting polypeptides (OATP) 1A1), as the most down-regulated mRNA, and it is negatively correlated with serum cholic acid level. Prokineticin 2 (Prok2) mRNA, a cytokine-like molecule associated with gastrointestinal tract inflammation, was significantly down-regulated in ethanol-fed mice. Prok2 mRNA expression was negatively correlated with abundance of Allobaculum (genus), Coprococcus (genus), Lachnospiraceae (family), Lactococcus (genus), and Cobriobacteriaceae (family), while it positively correlated with Bacteroides (genus).

CONCLUSIONS

RNA-seq analysis revealed unique transcriptomic signatures in the liver and intestine following chronic plus binge ethanol feeding.

Immunopathobiology and therapeutic targets related to cytokines in liver diseases

Chronic liver injury with any etiology can progress to fibrosis and the end-stage diseases cirrhosis and hepatocellular carcinoma. The progression of liver disease is controlled by a variety of factors, including liver injury, inflammatory cells, inflammatory mediators, cytokines, and the gut microbiome. In the current review, we discuss recent data on a large number of cytokines that play important roles in regulating liver injury, inflammation, fibrosis, and regeneration, with a focus on interferons and T helper (Th) 1, Th2, Th9, Th17, interleukin (IL)-1 family, IL-6 family, and IL-20 family cytokines. Hepatocytes can also produce certain cytokines (such as IL-7, IL-11, and IL-33), and the functions of these cytokines in the liver are briefly summarized. Several cytokines have great therapeutic potential, and some are currently being tested as therapeutic targets in clinical trials for the treatment of liver diseases, which are also described.

Paneth cell α-defensin misfolding correlates with dysbiosis and ileitis in Crohn's disease model mice

This study provides novel insight into Crohn’s disease where α-defensin misfolding resulting from excessive ER stress in Paneth cells induces dysbiosis and disease progression.

Crohn’s disease (CD) is an intractable inflammatory bowel disease, and dysbiosis, disruption of the intestinal microbiota, is associated with CD pathophysiology. ER stress, disruption of ER homeostasis in Paneth cells of the small intestine, and α-defensin misfolding have been reported in CD patients. Because α-defensins regulate the composition of the intestinal microbiota, their misfolding may cause dysbiosis. However, whether ER stress, α-defensin misfolding, and dysbiosis contribute to the pathophysiology of CD remains unknown. Here, we show that abnormal Paneth cells with markers of ER stress appear in SAMP1/YitFc, a mouse model of CD, along with disease progression. Those mice secrete reduced-form α-defensins that lack disulfide bonds into the intestinal lumen, a condition not found in normal mice, and reduced-form α-defensins correlate with dysbiosis during disease progression. Moreover, administration of reduced-form α-defensins to wild-type mice induces the dysbiosis. These data provide novel insights into CD pathogenesis induced by dysbiosis resulting from Paneth cell α-defensin misfolding and they suggest further that Paneth cells may be potential therapeutic targets.

The Role of Adaptor Protein CARD9 in Colitis-Associated Cancer

The adaptor protein CARD9 plays an important role in anti-fungal immunity responses, linking detection of fungi by surface receptors to activation of the transcription factor nuclear factor κB (NF-κB). Recent studies indicate that CARD9 also plays different but vital roles during the development of colitis-associated colorectal cancer (CAC). This review summarizes the current understanding of CARD9 functions in CAC, and we discuss its potentially carcinogenic mechanisms.