Protective effects of sodium butyrate on rotavirus inducing endoplasmic reticulum stress-mediated apoptosis via PERK-eIF2α signaling pathway in IPEC-J2 cells

Butyrate Derivatives Exhibited Anti-Inflammatory Effects and Enhanced Intestinal Barrier Integrity in Porcine Cell Culture Models

Butyrate and its derivatives may influence inflammatory status and physiology in a variety of organisms and organ systems. Inflammatory conditions of the gastrointestinal tract, such as post-weaning diarrhea, negatively impact swine. Dietary intervention with butyrate-based compounds should be considered a strategy to improve disease resistance in pigs. We aimed to assess the properties of different forms of butyrate treatments using porcine cell culture experiments. This assessment may inform future in vivo feed experiments designed to determine its potential application of the dietary supplements for pigs. An intestinal porcine enterocyte cell line, IPEC-J2, was seeded at 5 × 103 cells/mL in 96-well plates to confirm cell viability by MTT assay for each dose range used in the current experiments (0, 0.5, 1, 2, 4 mM butyric acid or tributyrin; 0, 1, 2, 4, 8 mM sodium butyrate or monobutyrin). For transepithelial electrical resistance (TEER) analysis, IPEC-J2 was seeded at 5 × 105 cells/mL in 12-well transwell inserts and treated with 5 levels of each butyrate derivative after adherence (n = 5). TEER was measured at 24, 48, and 72 h post-treatment to quantify intestinal barrier integrity of IPEC-J2 monolayers. Butyric acid, sodium butyrate, and monobutyrin significantly increased (p < 0.05) TEER in IPEC-J2 at different time points compared with control. Further, porcine alveolar macrophages (PAMs) were harvested from donor weaned piglets (n = 6) via bronchoalveolar lavage and isolated for primary culture (6 × 105 cells/well, 6-well plates). PAMs were treated with five levels of each butyrate derivative with or without lipopolysaccharide (LPS, 1 μg/mL) challenge. The concentrations of TNF-α and IL-1β in cell culture supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Butyric acid and sodium butyrate treatments reduced the production of TNF-α in LPS-challenged PAMs (linear; p < 0.05). Different butyrate derivatives exerted anti-inflammatory properties and improved intestinal barrier integrity.

Effects of Portulaca oleracea L. Polysaccharide on piglets infected with porcine rotavirus

Piglet diarrhea stands as the primary cause of piglet mortality, inflicting substantial economic losses to pig farmers. Porcine rotavirus (PoRV), a member of the Reoviridae family, bears responsibility for instigating diarrhea and severe dehydration, culminating in piglet fatalities. Portulaca oleracea L. (POL), a Chinese medicinal herb commonly utilized for its antiviral properties and effectiveness in treating diarrhea, holds promise for mitigating these effects. Nevertheless, the in vivo antiviral effect of Portulaca oleracea L. polysaccharide (POL-P), a key component of POL, on PoRV infection remains obscure. This study aimed to investigate the antiviral effects of POL-P on PoRV in piglets and its impact on their intestinal flora. Studies have demonstrated that oral POL-P improves growth in both lactating mice and PoRV-infected piglets, while reducing diarrhea and mortality. It also helps to reduce intestinal damage and lower viral mRNA levels in the jejunum and ileum. Additionally, POL-P improves blood tests in piglets, boosting levels of IFN-α and IL-10, and lowering tumor necrosis factor-α and IL-6. Analysis of the intestinal flora in PoRV-infected piglets showed reduced levels of Bacteroides (18.39 %) and increased levels of Firmicutes (39.81 %), Proteobacteria (33.46 %), and Verrucomicrobia (7.42 %). After POL-P treatment, Bacteroides increased to 28.31 %, while Firmicutes, Proteobacteria, and Verrucomicrobia decreased to 34.93 %, 25.52 %, and 2.53 %, respectively. At the genus level, POL-P treatment reduced the abundance of Klebsiella, Ackermannia, and Streptococcus. In conclusion, POL-P helps reduce inflammation and intestinal damage caused by PoRV infection, prevents viral colonization, restores gut flora balance, improves piglet growth, and reduces diarrhea and mortality.

Short-chain fatty acids in viral infection: the underlying mechanisms, opportunities, and challenges

Viral infections can cause cellular pathway derangements, cell death, and immunopathological responses, leading to host inflammation. Short-chain fatty acids (SCFAs), produced by the microbiota, have emerged as a potential therapeutic for viral infections due to their ability to modulate these processes. However, SCFAs have been reported to have both beneficial and detrimental effects, necessitating a comprehensive understanding of the underlying mechanisms. This review highlights the complex mechanisms underlying SCFAs' effects on viral infection outcomes. We also emphasize the importance of considering how SCFAs' activities may differ under diverse contexts, including but not limited to target cells with different metabolic wiring, different viral causes of infection, the target organism/cell's nutrient availability and/or energy balance, and hosts with varying microbiome compositions.

1α,25-hydroxyvitamin D3 alleviated rotavirus infection induced ferroptosis in IPEC-J2 cells by regulating the ATF3-SLC7A11-GPX4 axis

Rotavirus (RV) mainly infects mature intestinal epithelial cells and impairs intestinal absorption function, which leads to the death of infected cells and eventually fatal diarrhea. Ferroptosis is a novel regulatory cell death pattern, which can be caused by virus infection. 1α,25-hydroxyvitamin D3 (1,25D3) has an anti-RV infection effect and can regulate ferroptosis. However, whether RV infection can induce ferroptosis, and whether 1,25D3 can inhibit RV infection by regulating ferroptosis has not yet been studied. Present study shows that RV infection or erastin treatment induces IPEC-J2 cell death, which results in mitochondrial shrinkage, decreased mitochondrial membrane potential (MMP) and glutathione (GSH) content, increased MMP, intracellular Fe2+, reactive oxygen species (ROS), and malondialdehyde (MDA) contents. Meanwhile, ferrostatin-1 (Fer-1), liproxstatin-1 (Lip-1), and deferoxamine (DFO) treatment can effectively reverse the increase of intracellular Fe2+, ROS and MDA levels induced by RV infection. Moreover, RV infection increases activating transcription factor 3 (ATF3) mRNA and protein expressions, and inhibited SLC7A11 and glutathione peroxidase 4 (GPX4) expressions, which was partially alleviated by siATF3. 1,25D3 treatment significantly eliminates RV induced ferroptosis via ATF3-SLC7A11-GPX4 axis. Therefore, these results reveals that RV infection induces ferroptosis in IPEC-J2 cell and 1,25D3 alleviates RV induced ferroptosis by regulating the ATF3-SLC7A11-GPX4 axis.

Development of an intestinal epithelial cell line and organoids derived from the same swine and characterization of their antiviral responses

Intestinal homeostasis and integrity are important factors for maintaining host health. This study established intestinal epithelial cell lines and organoids from the same swine jejunal crypts to develop seamless swine intestinal in vitro evaluation systems. The study evaluated the proliferative capacity and tight junction formation of the epithelial cell line and characterized the cell differentiation potential of the intestinal organoids. The evaluation systems were subsequently exposed to the Toll-like receptor 3 (TLR3) agonist poly(I:C) to simulate viral infections and assess the antiviral responses. The results demonstrated no differences in the response to type I interferons. There were, however, significant differences in the expression of interferon-stimulated genes. This study collectively introduced a flexible evaluation system using cell lines and organoids and revealed notable differences in the expression of interferon-stimulated genes, highlighting the complexity of the immune responses in these in vitro systems and the importance of intestinal heterogeneity in assessing viral responses.

The protective role of prebiotics and probiotics on diarrhea and gut damage in the rotavirus-infected piglets

Rotavirus is one of the pathogenic causes that induce diarrhea in young animals, especially piglets, worldwide. However, nowadays, there is no specific drug available to treat the disease, and the related vaccines have no obvious efficiency in some countries. Via analyzing the pathogenesis of rotavirus, it inducing diarrhea is mainly due to disturb enteric nervous system, destroy gut mucosal integrity, induce intracellular electrolyte imbalance, and impair gut microbiota and immunity. Many studies have already proved that prebiotics and probiotics can mitigate the damage and diarrhea induced by rotavirus infection in hosts. Based on these, the current review summarizes and discusses the effects and mechanisms of prebiotics and probiotics on rotavirus-induced diarrhea in piglets. This information will highlight the basis for the swine production utilization of prebiotics and probiotics in the prevention or treatment of rotavirus infection in the future.

Peste des petits ruminants virus infection induces endoplasmic reticulum stress and apoptosis via IRE1-XBP1 and IRE1-JNK signaling pathways

BACKGROUND

Peste des petits ruminants (PPR) is a contagious and fatal disease of sheep and goats. PPR virus (PPRV) infection induces endoplasmic reticulum (ER) stress-mediated unfolded protein response (UPR). The activation of UPR signaling pathways and their impact on apoptosis and virus replication remains controversial.

OBJECTIVES

To investigate the role of PPRV-induced ER stress and the IRE1-XBP1 and IRE1-JNK pathways and their impact on apoptosis and virus replication.

METHODS

The cell viability and virus replication were assessed by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, immunofluorescence assay, and Western blot. The expression of ER stress biomarker GRP78, IRE1, and its downstream molecules, PPRV-N protein, and apoptosis-related proteins was detected by Western blot and quantitative reverse transcription-polymerase chain reaction, respectively. 4-Phenylbutyric acid (4-PBA) and STF-083010 were respectively used to inhibit ER stress and IRE1 signaling pathway.

RESULTS

The expression of GRP78, IRE1α, p-IRE1α, XBP1s, JNK, p-JNK, caspase-3, caspase-9, Bax and PPRV-N were significantly up-regulated in PPRV-infected cells, the expression of Bcl-2 was significantly down-regulated. Due to 4-PBA treatment, the expression of GRP78, p-IRE1α, XBP1s, p-JNK, caspase-3, caspase-9, Bax, and PPRV-N were significantly down-regulated, the expression of Bcl-2 was significantly up-regulated. Moreover, in PPRV-infected cells, the expression of p-IRE1α, p-JNK, Bax, and PPRV-N was significantly decreased, and the expression of Bcl-2 was increased in the presence of STF-083010.

CONCLUSIONS

PPRV infection induces ER stress and IRE1 activation, resulting in apoptosis and enhancement of virus replication through IRE1-XBP1s and IRE1-JNK pathways.

Porcine IGFBP3 promotes porcine circovirus type 2 replication via PERK/eIF2α mediated DNA damage

The infection of porcine circovirus type 2 (PCV2) triggers activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway and leads to DNA damage. Insulin-like growth factor-binding protein 3 (IGFBP3) may interact with the endoplasmic reticulum (ER). It remains unclear whether IGFBP3 regulates DNA damage via ER stress to mediate PCV2 replication. In this study, we observed an upregulation of porcine IGFBP3 expression during PCV2 infection, and overexpression of IGFBP3 enhanced the expression of PCV2 Cap protein, PCV2 DNA copy number, and viral titers in PK-15 B6 cells and 3D4/21 cells. Additionally, overexpression of IGFBP3 induced an increase in the DNA damage marker γH2AX by activating the PERK/eIF2α pathway without concomitant activation of ATF4, IRE1α, and ATF6α/GRP78 pathways in PK-15 B6 cells and 3D4/21 cells. Knockdown of IGFBP3 had a reverse effect on PCV2 replication in PK-15 B6 cells and 3D4/21 cells. Furthermore, treatment with etoposide enhanced PCV2 replication while KU57788 decreased it. GSK2606414 and salubrinal limited both DNA damage and viral replication. Therefore, our findings suggest that porcine IGFBP3 promotes PCV2 replication through the PERK/eIF2α pathway-mediated induction of DNA damage in PK-15 B6 cells and 3D4/21 cells. Our study provides a basis for exploring novel antiviral strategies via the extensive understanding of the relationships between host cellular proteins and viral replication.

Sodium butyrate protects against rotavirus-induced intestinal epithelial barrier damage by activating AMPK-Nrf2 signaling pathway in IPEC-J2 cells

Rotavirus (RV) mainly infects intestinal epithelial cells, which leads to diarrhea in newborn piglets with dysfunction in the intestinal mucosal mechanical barrier. Sodium butyrate (SB) is one of the metabolites excreted by gut microbes. However, the protective effect of SB on RV infection induced intestinal mucosal mechanical barrier injury and its potential mechanism has not been well elucidated. In the present study, IPEC-J2 cells with RV infection was a model of intestinal mucosal mechanical barrier injury. Our results demonstrated that the appropriate concentration of SB can effectively alleviate TJ structural damage and up-regulating the expression of TJ-related genes. Furthermore, the appropriate concentration of SB can effectively reverse the increase of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) level induced by RV infection. Meanwhile, the levels of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-px) and antioxidant proteins NAD(P)H dehydrogenase quinone 1 (NQO1) and heme oxygenase-1 (HO-1) were increased through SB treatment. In addition, we found that SB increased cellular antioxidant capacity by activating the adenosine monophosphate-activated protein kinase (AMPK)-nuclear factor erythroid 2-related factor (Nrf2) signaling pathway and the cytoprotective effect of SB is limited by GPR109A siRNA. Thus, our findings revealed that SB reduces oxidative stress caused by RV infection and restores the intestinal mucosal mechanical barrier function by activating the AMPK-Nrf2 signal pathway mediated by the receptor GPR109A.

Niacin Improves Intestinal Health through Up-Regulation of AQPs Expression Induced by GPR109A

(1) Background: Changes in the expression of aquaporins (AQPs) in the intestine are proved to be associated with the attenuation of diarrhea. Diarrhea is a severe problem for postweaning piglets. Therefore, this study aimed to investigate whether niacin could alleviate diarrhea in weaned piglets by regulating AQPs expression and the underlying mechanisms; (2) Methods: 72 weaned piglets (Duroc × (Landrace × Yorkshire), 21 d old, 6.60 ± 0.05 kg) were randomly allotted into 3 groups for a 14-day feeding trial. Each treatment group included 6 replicate pens and each pen included 4 barrows (n = 24/treatment). Piglets were fed a basal diet (CON), a basal diet supplemented with 20.4 mg niacin/kg diet (NA) or the basal diet administered an antagonist for the GPR109A receptor (MPN). Additionally, an established porcine intestinal epithelial cell line (IPEC-J2) was used to investigate the protective effects and underlying mechanism of niacin on AQPs expression after Escherichia coli K88 (ETEC K88) treatment; (3) Results: Piglets fed niacin-supplemented diet had significantly decreased diarrhea rate, and increased mRNA and protein level of ZO-1, AQP 1 and AQP 3 in the colon compared with those administered a fed diet supplemented with an antagonist (p < 0.05). In addition, ETEC K88 treatment significantly reduced the cell viability, cell migration, and mRNA and protein expression of AQP1, AQP3, AQP7, AQP9, AQP11, and GPR109A in IPEC-J2 cells (p < 0.05). However, supplementation with niacin significantly prevented the ETEC K88-induced decline in the cell viability, cell migration, and the expression level of AQPs mRNA and protein in IPEC-J2 cells (p < 0.05). Furthermore, siRNA GPR109A knockdown significantly abrogated the protective effect of niacin on ETEC K88-induced cell damage (p < 0.05); (4) Conclusions: Niacin supplementation increased AQPs and ZO-1 expression to reduce diarrhea and intestinal damage through GPR109A pathway in weaned piglets.

Ciclopirox targets cellular bioenergetics and activates ER stress to induce apoptosis in non-small cell lung cancer cells

Background

Lung cancer remains a major cause of cancer-related mortality throughout the world at present. Repositioning of existing drugs for other diseases is a promising strategy for cancer therapies, which may rapidly advance potentially promising agents into clinical trials and cut down the cost of drug development. Ciclopirox (CPX), an iron chelator commonly used to treat fungal infections, which has recently been shown to have antitumor activity against a variety of cancers including both solid tumors and hematological malignancies in vitro and in vivo. However, the effect of CPX on non-small cell lung cancer (NSCLC) and the underlying mechanism is still unclear.

Methods

CCK-8, clonal formation test and cell cycle detection were used to observe the effect of inhibitor on the proliferation ability of NSCLC cells. The effects of CPX on the metastasis ability of NSCLC cells were analyzed by Transwell assays. Apoptosis assay was used to observe the level of cells apoptosis. The role of CPX in energy metabolism of NSCLC cells was investigated by reactive oxygen species (ROS) detection, glucose uptake, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) experiments. Western blot was used to examine the protein changes.

Results

We report that CPX inhibits NSCLC cell migration and invasion abilities through inhibiting the epithelial-mesenchymal transition, impairing cellular bioenergetics, and promoting reactive oxygen species to activate endoplasmic reticulum (ER) stress-induced apoptotic cell death. Moreover, CPX intraperitoneal injection can significantly inhibit NSCLC growth in vivo in a xenograft model.

Conclusions

Our study revealed that CPX targets cellular bioenergetics and activates unfolded protein response in ER to drive apoptosis in NSCLC cells, indicating that CPX may be a potential therapeutic drug for the treatment of NSCLC.

Graphical Abstract