Elevation of HO-1 Expression Mitigates Intestinal Ischemia-Reperfusion Injury and Restores Tight Junction Function in a Rat Liver Transplantation Model

The anti-fibrotic and anti-inflammatory effects of 2,4-diamino-5-(1-hydroxynaphthalen-2-yl)-5H-chromeno[2,3-b] pyriine-3-carbonitrile in corneal fibroblasts

BACKGROUND

Although several studies had addressed the anti-inflammatory effects of derivatives of 4H-chromene and chromeno[2,3-b]pyridine in the different types of cells, whether these derivatives would exert beneficial anti-fibrotic effects during corneal fibrotic scar formation was unclear.

METHODS

We examined the cyclooxygenase-2 (COX-2) expression of 2,4-diamino-5-(1-hydroxynaphthalen-2-yl)-5H-chromeno[2,3-b]pyridine-3-carbonitrile (N1) in the human corneal fibroblasts (HCFs) under the treatment TGF-β1. Signaling pathways underlying the mechanism of the N1 effect on the HCFs were determined.

RESULTS

Application of N1 significantly decreased COX-2 expression after 2 h and 4 h in the HCFs stimulated with TGF-β1. Notably, reduced production of extracellular matrix proteins under N1 treatment was found, including fibronectin, collagen I, and matrix metallopeptidase 9. Immunoblot analysis showed that treatment with N1 significantly attenuated phosphorylation of both STAT3 and Smad 2 in the TGF-β1-stimulated HCFs. Upregulated mRNA of Smad2 and downregulated mRNA of Smad3 were observed using the quantitative real-time polymerase chain reaction. In addition, N1 induced significant increases in HO-1 and Nrf2 expression, but inhibited phosphorylation of NF-κB in the HCFs treated with TGF-β1.

CONCLUSIONS

Our findings show for the first time that N1 exerts anti-fibrotic and anti-inflammatory effects through suppression of COX-2, Smad2, STAT3, iNOS and NF-κB expressions as well as upregulation of Nrf2 and HO-1 expressions, which suggests they are potential therapeutic targets in the treatment of corneal fibrosis.

Neutrophil Elastase Inhibitors Suppress Oxidative Stress in Lung during Liver Transplantation

Background

Neutrophil infiltration plays a critical role in the pathogenesis of acute lung injury following liver transplantation (LT). Neutrophil elastase is released from neutrophils during pulmonary polymorphonuclear neutrophil activation and sequestration. The aim of the study was to investigate whether the inhibition of neutrophil elastase could lead to the restoration of pulmonary function following LT.

Methods

In in vivo experiments, lung tissue and bronchoalveolar lavage fluid (BALF) were collected at 2, 4, 8, and 24 h after rats were subjected to orthotopic autologous LT (OALT), and neutrophil infiltration was detected. Next, neutrophil elastase inhibitors, sivelestat sodium hydrate (exogenous) and serpin family B member 1 (SERPINB1) (endogenous), were administered to rats before OALT, and neutrophil infiltration, pulmonary oxidative stress, and barrier function were measured at 8 h after OALT.

Results

Obvious neutrophil infiltration occurred from 2 h and peaked at 8 h in the lungs of rats after they were subjected to OALT, as evidenced by an increase in naphthol-positive cells, BALF neutrophil elastase activity, and lung myeloperoxidase activity. Treatment with neutrophil elastase inhibitors, either sivelestat sodium hydrate or SERPINB1, effectively reduced lung naphthol-positive cells and BALF inflammatory cell content, increased expression of lung HO-1 and tight junction proteins ZO-1 and occludin, and increased the activity of superoxide dismutase.

Conclusion

Neutrophil elastase inhibitors, sivelestat sodium hydrate and SERPINB1, both reduced lung neutrophil infiltration and pulmonary oxidative stress and finally restored pulmonary barrier function.

The Carcinogenic Agent Diethylnitrosamine Induces Early Oxidative Stress, Inflammation and Proliferation in Rat Liver, Stomach and Colon: Protective Effect of Ginger Extract

Background: Diethylnitrosamine (DENA), a well-known dietary carcinogen, related to cancer initiation of various organs. The present study investigated the deleterious mechanisms involved in the early destructive changes of DENA in different organs namely, liver, stomach and colon and the potential protective effect of GE against these mechanisms. Methods: Adult male albino rats were assigned into four groups. A normal control group received the vehicle, another group was injected with a single necrogenic dose of DENA (200 mg/kg, i.p) on day 21. Two groups received oral GE (108 or 216 mg/kg) daily for 28 days. Sera, liver, stomach and colon were obtained 7 days after DENA injection. Serum aspartate transaminase and alanine transaminase were detected as well as reduced glutathione (GSH), malondialdehyde, nitric oxide metabolites, interleukin 1β, tumor necrosis factor (TNF-α), alpha-fetoprotein (AFP) and nuclear factorerythroid 2-related factor2 (Nrf2) in liver, stomach and colon. Histopathological studies and immunohistochemical examination of cyclooxygenase-2 (COX2) were conducted. Results: DENA induced elevation in liver function enzymes with significant increase in oxidation and inflammation biomarkers and AFP while decreased levels of Nrf2 in liver, stomach and colon were detected. Histologically, DENA showed degenerative changes in hepatocytes and inflammatory foci. Inflammatory foci displayed increased expression of COX2 in immunohistochemical staining. GE-pretreatment improved liver function and restored normal GSH with significant mitigation of oxidative stress and inflammatory biomarkers compared to DENA-treated group. AFP was reduced by GE in both doses, while Nrf2 increased significantly. Histology and immunostaining of hepatic COX-2 were remarkably improved in GE-treated groups in a dose dependent manner. Conclusion: GE exerted a potential anti-proliferative activity against DENA in liver, stomach and colon via Nrf2 activation, whilst suppression of oxidation and inflammation.

A Protective Role of the NRF2-Keap1 Pathway in Maintaining Intestinal Barrier Function

Nrf2 (NF-E2-related factor 2) is a master regulator of cellular oxidative levels against environmental stresses. Nrf2 induces the expression of metabolic detoxification and antioxidant enzymes to eliminate reactive oxygen species (ROS). The gastrointestinal tract is a key source of ROS. Intestinal barrier is critical to maintain the healthy steady state of the human gastrointestinal tract. Nrf2 has been shown to play important roles in maintaining the integrity of intestinal mucosal barrier. Here, we made a systematic review on the roles of Nrf2 in maintaining intestinal barrier, including the following: (1) NRF2 reduced intestinal mucosal injury by suppressing oxidative stress; (2) NRF2 decreased intestinal inflammation by inhibiting the inflammatory pathway; (3) NRF2 affected intestinal tight junction proteins and apoptosis of cells to regulate intestinal permeability; (4) NRF2 affected T cell differentiation and functions; (5) the crossregulation between the KEAP1-NRF2 pathway and autophagy controlled intestinal oxidative stress.

5-ALA/SFC Attenuated Binge Alcohol-Induced Gut Leakiness and Inflammatory Liver Disease in HIV Transgenic Rats

BACKGROUND

This study aimed to investigate the protective effect of 5-aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) against binge alcohol-induced gut leakiness and inflammatory liver disease in HIV transgenic (TG) rats.

METHODS

TG rats were treated with 3 consecutive doses of binge ethanol (EtOH) with or without 5-ALA/SFC. Blood and liver tissue samples were collected at 6 hours following the last dose of EtOH.

RESULTS

Compared with the wild-type (WT) rats, the TG rats showed increased sensitivity to alcohol-mediated inflammation, as evidenced by the significantly elevated levels of serum endotoxin, AST, ALT, ED1, and ED2 staining in liver. In contrast, 5-ALA/SFC improved the above biochemical and histochemical profiles. 5-ALA/SFC also attenuated the up-regulated mRNA expression of leptin and CCL2. Furthermore, down-regulated intestinal ZO-1 protein expression was also inhibited by 5-ALA/SFC. Moreover, the expressions of HO-1, HO-2, Sirt1, and related signal transduction molecules in liver were increased by 5-ALA/SFC. These results demonstrated that 5-ALA/SFC treatment ameliorated binge alcohol exposure liver injury in a rat model of HIV-infected patients by reducing macrophage activation and expression of inflammatory cytokines/chemokines, and by inducing HO-1, HO-2, and Sirt1 expression.

CONCLUSIONS

Taken together, these findings suggested that treatment with 5-ALA/SFC has a potential therapeutic effect for binge alcohol exposure liver injury in HIV-infected patients.

Activation of HO-1 protects placental cells function in oxidative stress via regulating ZO-1/occludin

We previously confirmed that Nuclear factor erythroid 2-related factor-2 (Nrf2) and heme oxygenase (HO-1) play synergistic roles in the pathogenesis of preeclampsia. To further explore the function of HO-1 in the pathogenesis of preeclampsia, we established oxidative stress models respectively with human first-trimester trophoblast/simian virus (HTR8/SVneo) and human umbilical vein endothelial cells (HUVECs) and then assessed the effect of HO-1 on the two cell lines in oxidative stress conditions. The cell oxidative stress models were incubated with Hemin (an inducer of HO-1), then, the HTR8/SVneo cells were transfected by ZO-1 small interfering RNA (siRNA). The HTR-8/SVneo invasive abilities were detected, and the tube formation abilities of HUVECs were measured. HO-1 and tight junction proteins zonula occludens-1 (ZO-1) and occludin in the cells were detected. In both the trophoblastic and HUVEC oxidative stress models, HO-1、ZO-1 and occludin were increased incubated with Hemin. Meanwhile, HTR-8/SVneo cells incubated with Hemin showed increased invasion function against the destruction of hydrogen peroxide (H₂O₂). Similarly, the tube formation ability of HUVECs incubated with Hemin was increased. The above-mentioned effects were disappeared after HTR-8/SVneo cells were transfected by ZO-1 siRNA. These results suggest that HO-1 protects the function of placental cells in oxidative stress via regulating ZO-1/occludin.

Oxidative Stress and Nutraceuticals in the Modulation of the Immune Function: Current Knowledge in Animals of Veterinary Interest

In the veterinary sector, many papers deal with the relationships between inflammation and oxidative stress. However, few studies investigate the mechanisms of action of oxidised molecules in the regulation of immune cells. Thus, authors often assume that these events, sometime leading to oxidative stress, are conserved among species. The aim of this review is to draw the state-of-the-art of the current knowledge about the role of oxidised molecules and dietary antioxidant compounds in the regulation of the immune cell functions and suggest some perspectives for future investigations in animals of veterinary interest.

Dexmedetomidine Attenuates Orthotopic Liver Transplantation-Induced Acute Gut Injury via α 2-Adrenergic Receptor-Dependent Suppression of Oxidative Stress

Patients with orthotopic liver transplantation (OLT) frequently develop acute gut injury (AGI), and dexmedetomidine (Dex) has been reported to exert a protective effect against AGI. We investigated whether Dex protects against AGI through antioxidative stress effects by the Nrf2/HO-1 antioxidative signaling pathway. Rats were randomly allocated into a sham group and six orthotopic autologous liver transplantation (OALT) groups receiving different doses of Dex together with/without α ₂-adrenergic receptor (AR) blockers. Intestinal tissues were collected to visualize the barrier damage and to measure the indexes of oxidative stress. For in vitro studies, rat intestinal recess epithelial cells (IEC-6) underwent hypoxia/reoxygenation (H/R), and the protective role of Dex was evaluated after α _2A-AR siRNA silencing. OALT resulted in increased oxidative stress, significant intestinal injury, and barrier dysfunction. Dex attenuated OALT-induced oxidative stress and intestinal injury, which was abolished by the pretreatment with the nonspecific α _2A-AR siRNA blocker atipamezole and the specific α _2A-AR siRNA blocker BRL-44408, but not by the specific _2B/C-AR siRNA blocker ARC239. Silencing of α _2A-AR siRNA also attenuated the protective role of Dex on alleviating oxidative stress in IEC-6 cells subjected to H/R. Dex exerted its protective effects by activating Nrf2/HO-1 antioxidative signaling. Collectively, Dex attenuates OALT-induced AGI via α _2A-AR-dependent suppression of oxidative stress, which might be a novel potential therapeutic target for OALT-induced AGI.

Characterization and evolution of intestine injury at the anhepatic phase in portal hypertensive rats

The aim of the present study was to investigate the characteristics and progression of intestinal injury at the anhepatic phase in portal hypertensive rats. A total of 120 healthy male Wistar rats were purchased, with 15 rats in the normal control group and 105 rats were assigned to establish a prehepatic portal hypertension model. The 105 model rats were further divided into seven treatment groups following ischemia-reperfusion. Meanwhile, portal vein pressure, the area of lower esophageal mucosal vein, endotoxin levels in portal vein blood and the level of malondialdehyde (MDA) and superoxide dismutase (SOD) were measured. Morphology changes of the intestine were observed using optical microscopy and transmission electron microscopy. A portal hypertension rat model was successfully established. Furthermore, endotoxin, MDA and SOD level reached a peak at 12-24 h following reperfusion and then decreased gradually to normal levels at 1 week following reperfusion. However, cytological damage did not recover to preoperative level within 1 week. These findings suggest that intestinal injury was most severe within 12-24 h following ischemia-reperfusion and most indicators recovered to almost normal levels. Therefore, further study on the intestinal mucosal damage is required, with the aim to reduce the production of intestinal endotoxin.

Falcarinol Is a Potent Inducer of Heme Oxygenase-1 and Was More Effective than Sulforaphane in Attenuating Intestinal Inflammation at Diet-Achievable Doses

Nuclear factor- (erythroid-derived 2) like 2 (Nrf2) is a transcription factor that regulates the expression of a battery of antioxidant, anti-inflammatory, and cytoprotective enzymes including heme oxygenase-1 (Hmox1, Ho-1) and NADPH:quinone oxidoreductase-1 (Nqo1). The isothiocyanate sulforaphane (SF) is widely understood to be the most effective natural activator of the Nrf2 pathway. Falcarinol (FA) is a lesser studied natural compound abundant in medicinal plants as well as dietary plants from the Apiaceae family such as carrot. We evaluated the protective effects of FA and SF (5 mg/kg twice per day in CB57BL/6 mice) pretreatment for one week against acute intestinal and systemic inflammation. The phytochemical pretreatment effectively reduced the magnitude of intestinal proinflammatory gene expression (IL-6, Tnfα/Tnfαr, Infγ, STAT3, and IL-10/IL-10r) with FA showing more potency than SF. FA was also more effective in upregulating Ho-1 at mRNA and protein levels in both the mouse liver and the intestine. FA but not SF attenuated plasma chemokine eotaxin and white blood cell growth factor GM-CSF, which are involved in the recruitment and stabilization of first-responder immune cells. Phytochemicals generally did not attenuate plasma proinflammatory cytokines. Plasma and intestinal lipid peroxidation was also not significantly changed 4 h after LPS injection; however, FA did reduce basal lipid peroxidation in the mesentery. Both phytochemical pretreatments protected against LPS-induced reduction in intestinal barrier integrity, but FA additionally reduced inflammatory cell infiltration even below negative control.

Ferulic acid protects against heat stress-induced intestinal epithelial barrier dysfunction in IEC-6 cells via the PI3K/Akt-mediated Nrf2/HO-1 signaling pathway

PURPOSE

Intestinal epithelial barrier dysfunction is crucial in the pathogenesis of intestinal and systemic diseases. Ferulic acid (FA) possesses promising antioxidant activities. In a previous study, we demonstrated potentially protective effects of FA against heat stress-induced intestinal epithelial barrier dysfunction in IEC-6 cells. However, the underlying mechanisms are unclear. The present study aimed to elucidate whether FA protects IEC-6 cells from heat stress-induced intestinal epithelial barrier dysfunction via antioxidative mechanisms.

MATERIALS AND METHODS

IEC-6 cells were pretreated with FA prior to hyperthermia exposure at 42 °C for 6 h, and the levels of intracellular reactive oxygen species (ROS), malondialdehyde (MDA), nitrogen oxide (NO), and superoxide dismutase (SOD) activity were analyzed. The intestinal epithelial barrier function was determined by transepithelial electrical resistance (TER) values and 4-kDa fluorescein isothiocyanate-dextran (FD4) flux in IEC-6 cell monolayers. Expression of related proteins was detected by Western blotting.

RESULTS

FA suppressed heat stress-induced intestinal oxidative stress damage by reducing ROS, MDA and NO production, while enhancing SOD activity. Furthermore, FA treatment strengthened intestinal barrier function via increasing the phosphorylation levels of Akt, nuclear factor-erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) protein expression, which was reversed by zinc protoporphyrin (an HO-1 inhibitor). Additionally, LY294002, a specific PI3K/Akt inhibitor, significantly suppressed FA-induced Nrf2 nuclear translocation and HO-1 protein expression and inhibited FA-induced occludin and ZO-1 protein expression.

CONCLUSIONS

FA protected against heat stress-induced intestinal epithelial barrier dysfunction via activating the PI3K/Akt-mediated Nrf2/HO-1 signaling pathway in IEC-6 cells.

Effect of heme oxygenase-1 on the protection of ischemia reperfusion injury of bile duct in rats after liver transplantation

OBJECTIVE

To investigate the effect of heme oxygenase-1 (HO-1) on the ischemic reperfusion injury (IRI) of bile duct in rat models after liver transplantation.

METHODS

320 SD rats were equally and randomly divided into 5 groups, which were group A receiving injection of 3×10⁸/pfu/ml adenovirus (adv), group B with donor receiving Adv-HO-1 and recipient receiving Adv-HO-1-siRNA, group C with donor and recipient both receiving Adv-HO-1, group D with donor receiving Adv-HO-1-siRNA and recipient receiving Adv-HO-1, and group E with donor and recipient both receiving Adv-HO-1-siRNA at 24h before liver transplantation. Donor liver was stored in UW liquid at 4°C followed by measuring HO-1 level by western blot before transplantation. On d1, d3, d7 and d14, serum and liver was isolated for analysis of liver function, inflammatory cell infiltration by H&E staining, ultrastructure of liver by transmission electron microscopy as well as the expression of HO-1, Bsep, Mrp2 and Ntcp by western blot.

RESULTS

Compared with group D and E, group B and C displayed improved liver function as demonstrated by lower level of ALT, AST, LDH, TBIL, ALP and GGT, increased secretion of TBA and PL as well as expression of transporter proteins (Bsep, Mrp2 and Ntcp), reduced inflammatory cells infiltration and liver injury.

CONCLUSION

Our study demonstrated that overexpression of HO-1 in donor liver can ameliorate the damage to bile duct and liver, and improved liver function, suggesting HO-1 might be a new therapeutic target in the treatment of IRI after liver transplantation.

Effects of sub-chronic exposure to atmospheric PM2.5 on fibrosis, inflammation, endoplasmic reticulum stress and apoptosis in the livers of rats

Epidemiological studies have revealed that exposure to PM2.5 is linked to liver cancer. However, the hepatic toxicity and relevant molecular mechanisms of PM2.5 have not yet been fully described. Herein, we report on our investigation of the fibrosis, inflammation, endoplasmic reticulum (ER) stress and apoptosis in the livers of rats, caused by exposure to PM2.5 during summer and winter in Taiyuan, China. Male SD rats were sub-chronically exposed to PM2.5 (in summer: 0.2, 0.6, 1.5 mg per kg of b.w.; in winter: 0.3, 1.5, 2.7 mg per kg of b.w.) via intratracheal instillation once every 3 days for 60 days. The results showed that exposure to high dosages of PM2.5 caused the following: (1) hepatic histopathological changes and liver function decline through elevating the activities of AST, ALT, CYP450 and GST; (2) triggered liver fibrosis, in which TGF-β1, Col I, Col III, and MMP13 mRNA and protein expression were significantly upregulated, and enhanced inflammation with the overexpression of TNF-α, IL-6 and HO-1 versus the control; (3) induced liver ER stress and cell apoptosis via activating the GRP78/ATF6/CHOP/TRB3/caspase 12 pathway. The data also indicated that the liver injury induced by winter PM2.5 in Taiyuan was more serious compared to that induced by summer PM2.5. This work provides new insight into the mechanisms of PM2.5-induced liver injury, and aids the understanding of the underlying mechanisms by which PM2.5 might affect liver diseases.

Cobalt-protoporphyrin enhances heme oxygenase 1 expression and attenuates liver ischemia/reperfusion injury by inhibiting apoptosis

The aim of the present study was to investigate the preconditioning effect and underlying mechanisms of cobalt-protoporphyrin (CoPP) in a mouse model of liver ischemia‑reperfusion (I/R) injury. Mice were divided into five groups: Sham‑operated (control), I/R, I/R + CoPP, I/R + CoPP and zinc‑protoporphyrin (ZnPP) and I/R + ZnPP. Serum levels of aspartate transaminase (AST) and alanine aminotransferase (ALT) were detected using commercial kits. The expression of the pro‑apoptotic protein caspase‑3 was detected by immunohistochemistry and the expression levels of the anti‑apoptotic protein B‑cell lymphoma 2 (Bcl‑2) and heme oxygenase 1 (HO‑1) were analyzed by western blotting. Sections of liver tissue were stained with hematoxylin and eosin to observe pathologic alterations. Furthermore, hepatocyte apoptosis was detected using a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. AST and ALT levels of the CoPP preconditioned group were significantly reduced compared with the IR injury group (P<0.05) and liver damage was attenuated. The expression levels of the pro‑apoptotic protein caspase3 was inhibited and those of HO‑1 and Bcl‑2 were increased in the CoPP group compared with the I/R group; the opposite results were observed in the ZnPP group. Furthermore, the percentage of apoptotic cells as detected by TUNEL was significantly decreased in the CoPP group compared with the I/R group (P<0.05); these protective effects were abrogated by ZnPP. In conclusion, the results of the present study suggested that CoPP may induce HO‑1 overexpression and produce anti‑apoptotic effects in liver I/R injury.

A causal mediation model of ischemia reperfusion injury in the retina

The goal of this study is to develop a model that explains the relationship between microRNAs, transcription factors, and their co-target genes. This relationship was previously reported in gene regulatory loops associated with 24 hour (24h) and 7 day (7d) time periods following ischemia-reperfusion injury in a rat's retina. Using a model system of retinal ischemia-reperfusion injury, we propose that microRNAs first influence transcription factors, which in turn act as mediators to influence transcription of genes via triadic regulatory loops. Analysis of the relative contributions of direct and indirect regulatory influences on genes revealed that a substantial fraction of the regulatory loops (69% for 24 hours and 77% for 7 days) could be explained by causal mediation. Over 40% of the mediated loops in both time points were regulated by transcription factors only, while about 20% of the loops were regulated entirely by microRNAs. The remaining fractions of the mediated regulatory loops were cooperatively mediated by both microRNAs and transcription factors. The results from these analyses were supported by the patterns of expression of the genes, transcription factors, and microRNAs involved in the mediated loops in both post-ischemic time points. Additionally, network motif detection for the mediated loops showed a handful of time specific motifs related to ischemia-reperfusion injury in a rat's retina. In summary, the effects of microRNAs on genes are mediated, in large part, via transcription factors.

The Protective Effect of Heme Oxygenase-1 against Intestinal Barrier Dysfunction in Cholestatic Liver Injury Is Associated with NF-κB Inhibition

Heme oxygenase-1 (HO-1) is reported to protect against liver injury, but little is known about its effect on the intestinal barrier in cholestatic liver injury. In this study, we investigated the effects of HO-1 and its enzymatic by-product on intestinal barrier dysfunction in bile duct ligation (BDL) rats and explored the possible mechanism. The HO-1 inducer cobalt protoporphyrin (CoPP) and carbon monoxide-releasing molecule-2 (CORM-2) were used; the expression levels of tight junction (TJ) proteins, intestinal inflammation and NF-κB p65 were measured. For an in vitro experiment, stable Caco-2 cell lines were constructed, one overexpressed the HO-1 gene and another with that gene knocked down, and the specific NF-κB inhibitor JSH-23 was used. CoPP and CORM-2 treatment alleviated liver and intestinal mucosa injury in BDL rats; improved ZO-1, claudin-1 and PCNA expression; and reduced cell apoptosis and intestinal interleukin-6 (IL-6) expression. In vitro studies confirmed that HO-1, ZO-1 and occludin were overexpressed in HO-1-transfected Caco-2 cells, while decreased in the sh-HO-1 group. JSH-23 significantly increased occludin expression in both the HO-1 overexpression and sh-HO-1 groups, compared with their respective controls. HO-1 overexpression also inhibited the nuclear translocation of NF-κB p65 after lipopolysaccharide (LPS) treatment. Additionally, phospho-p65 expression in sh-HO-1 cells was significantly increased compared with that of the HO-1 overexpression group. In conclusion, HO-1 and CORM-2 improved intestinal epithelial barrier function in BDL-induced cholestatic liver injury mainly by restoring TJ, reducing cell apoptosis and intestinal inflammation. HO-1 exerts a protective effect, which is partially correlated with the regulation of NF-κB.

6-Gingerol protects intestinal barrier from ischemia/reperfusion-induced damage via inhibition of p38 MAPK to NF-κB signalling

Intestinal ischemia reperfusion (I/R) injury caused by severe trauma, intestinal obstruction, and operation is one of the tough challenges in clinic. 6-Gingerol (6G), a main active ingredient of ginger, is found to have anti-microbial, anti-inflammatory, anti-oxidative, and anti-cancer activities. The present study was designed to characterize the potential protective effects of 6G on rat intestinal I/R injury and reveal the correlated mechanisms. Rat intestinal I/R model was established with clamping the superior mesenteric artery (SMA) and 6G was intragastrically administered for three consecutive days before I/R injury. Caco-2 and IEC-6 cells were incubated under hypoxia/reoxygenation (H/R) conditions to simulate I/R injury in vitro. The results showed that 6G significantly alleviated intestinal injury in I/R injured rats by reducing the generation of oxidative stress and inhibiting p38 MAPK signaling pathway. 6G significantly reduced MDA level and increased the levels of SOD, GSH, and GSH-Px in I/R injured intestinal tissues. 6G significantly decreased the production of proinflammatory cytokines including TNF-α, IL-1β, and IL-6, and inhibited the expression of inflammatory mediators iNOS/NO in I/R injured intestinal tissues. The impaired intestinal barrier function was restored by using 6G in I/R injured rats and in both Caco-2 and IEC-6 cells characterized by inhibiting p38 MAPK phosphorylation, nuclear translocation of NF-κB, and expression of myosin light chain kinase (MLCK) protein. 6G also reduced the generation of reactive oxygen species (ROS) in both Caco-2 and IEC-6 cells. In vitro transfection of p38 MAPK siRNA mitigated the impact of 6G on NF-κB and MLCK expression, and the results further corroborated the protective effects of 6G on intestinal I/R injury by repressing p38 MAPK signaling. In conclusion, the present study suggests that 6G exerts protective effects against I/R-induced intestinal mucosa injury by inhibiting the formation of ROS and p38 MAPK activation, providing novel insights into the mechanisms of this therapeutic candidate for the treatment of intestinal injury.

p-JAK2 plays a key role in catalpol-induced protection against rat intestinal ischemia/reperfusion injury

Catalpol attenuated rat intestinal I/R injury by decreasing mitochondria-mediated apoptosis through blocking the JAK2/STAT3 signaling pathwayviaselective inhibition of p-JAK2.

Lipoxin A4 Preconditioning Attenuates Intestinal Ischemia Reperfusion Injury through Keap1/Nrf2 Pathway in a Lipoxin A4 Receptor Independent Manner

Oxidative stress plays a critical role in the pathogenesis of intestinal ischemia reperfusion (IIR) injury. Enhancement in endogenous Lipoxin A4 (LXA4), a potent antioxidant and mediator, is associated with attenuation of IIR. However, the effects of LXA4 on IIR injury and the potential mechanisms are unknown. In a rat IIR (ischemia 45 minutes and subsequent reperfusion 6 hours) model, IIR caused intestinal injury, evidenced by increased serum diamine oxidase, D-lactic acid, intestinal-type fatty acid-binding protein, and the oxidative stress marker 15-F2t-Isoprostane. LXA4 treatment significantly attenuated IIR injury by reducing mucosal 15-F2t-Isoprostane and elevating endogenous antioxidant superoxide dismutase activity, accompanied with Keap1/Nrf2 pathway activation. Meanwhile, LXA4 receptor antagonist Boc-2 reversed the protective effects of LXA4 on intestinal injury but failed to affect the oxidative stress and the related Nrf2 pathway. Furthermore, Nrf2 antagonist brusatol reversed the antioxidant effects conferred by LXA4 and led to exacerbation of intestinal epithelium cells oxidative stress and apoptosis, finally resulting in a decrease of survival rate of rat. Meanwhile, LXA4 pretreatment upregulated nuclear Nrf2 level and reduced hypoxia/reoxygenation-induced IEC-6 cell damage and Nrf2 siRNA reversed this protective effect of LXA4 in vitro. In conclusion, these findings suggest that LXA4 ameliorates IIR injury by activating Keap1/Nrf2 pathway in a LXA4 receptor independent manner.