The role of tumor necrosis factor-alpha and interleukin-1beta in ischemia-reperfusion injury of the rat small intestine

The mechanism of intestinal stem cells differentiation after ischemia-reperfusion injury in a rat model

PURPOSE

Notch and Wnt/β-catenin signaling are responsible for regulation of intestinal stem cells (ISCs) proliferation and differentiation. The purpose of the study was to evaluate Wnt/β-catenin and Notch signaling roles in regulation of ISC differentiation following ischemia-reperfusion (IR) injury in a rat.

METHODS

Rats were assigned into two groups: Sham rats underwent laparotomy without vascular intervention and IR rats underwent occlusion of SMA and portal vein for 20 min followed by 48 h of reperfusion. Wnt/β-catenin and Notch-related gene expression were determined using Real-Time PCR. Enterocyte proliferation, differentiation and Wnt-related proteins were determined by immunohistochemistry.

RESULTS

IR rats demonstrated a significant decrease in β-catenin gene expression, a decrease in cyclin D1 and β-catenin positive cells in jejunum and ileum compared to Sham rats. IR rats demonstrated a significant increase in Notch-related gene expression in jejunum and ileum compared to Sham rats. The number of secretory cells was higher mainly in the jejunum and number of absorptive cells was significantly lower in jejunum and lower in ileum in IR rats compared to Sham rats.

CONCLUSIONS

Intestinal stem-cell differentiation is toward secretory cells 48 h after IR injury; however, Wnt/β-catenin pathway inhibition and Notch-related gene expression stimulation suggest crosstalk between pathways.

Naringin protects against inflammation and apoptosis induced by intestinal ischemia-reperfusion injury through deactivation of cGAS-STING signaling pathway

Effective amelioration of ischemia/reperfusion (I/R)-induced intestinal injury and revealing its mechanisms remain the challenges in both preclinic and clinic. Potential mechanisms of naringin in ameliorating I/R-induced intestinal injury remain unknown. Based on pre-experiments, I/R-injured rat intestine in vivo and hypoxia-reoxygenation (H/R)-injured IEC-6 cells in vitro were used to verify that naringin-alleviated I/R-induced intestinal injury was mediated via deactivating cGAS-STING signaling pathway. Naringin improved intestinal damage using hematoxylin and eosin staining and decreased alanine aminotransferase and aspartate aminotransferase contents in plasma. Naringin decreased inflammation characterized by reducing IL-6, IL-1β, TNF-α, and IFN-β contents in both plasma and IEC-6 cells. Naringin mitigated oxidative stress via recovering superoxide dismutase, glutathione, and malondialdehyde levels in the I/R-injured intestine. Naringin reduced the expression of apoptotic proteins, including Bax, caspase-3, and Bcl-2, and reduced terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling-positive cells both in vivo and in vitro, and decreased Hoechst 33342 signals in vitro. cGAS, STING, p-TBK1, p-IRF3, and NF-κB expressions were up-regulated both in vivo and in vitro respectively and the up-regulated indexes were reversed by naringin. Transfection of cGAS-siRNA and cGAS-cDNA significantly down-regulated and up-regulated cGAS-STING signaling-related protein expressions, respectively, and partially weakened naringin-induced amelioration on these indexes, suggesting that deactivation of cGAS-STING signaling is the crucial target for naringin-induced amelioration on I/R-injured intestine.

Early Growth Response-1: Friend or Foe in the Heart?

Cardiovascular disease is a major cause of mortality and morbidity worldwide. Early growth response-1 (Egr-1) plays a critical regulatory role in a range of experimental models of cardiovascular diseases. Egr-1 is an immediate-early gene and is upregulated by various stimuli including shear stress, oxygen deprivation, oxidative stress and nutrient deprivation. However, recent research suggests a new, underexplored cardioprotective side of Egr-1. The main purpose of this review is to explore and summarise the dual nature of Egr-1 in cardiovascular pathobiology.

Biomarkers of Intestinal Injury in Colic

Biomarkers are typically proteins, enzymes, or other molecular changes that are elevated or decreased in body fluids during the course of inflammation or disease. Biomarkers pose an extremely attractive tool for establishing diagnoses and prognoses of equine gastrointestinal colic, one of the most prevalent causes of morbidity and mortality in horses. This topic has received increasing attention because early diagnosis of some forms of severe colic, such as intestinal ischemia, would create opportunities for rapid interventions that would likely improve case outcomes. This review explores biomarkers currently used in equine medicine for colic, including acute phase proteins, proinflammatory cytokines, markers of endotoxemia, and tissue injury metabolites. To date, no single biomarker has been identified that is perfectly sensitive and specific for intestinal ischemia; however, L-lactate has been proven to be a very functional and highly utilized diagnostic tool. However, further exploration of other biomarkers discussed in this review may provide the key to accelerated identification, intervention, and better outcomes for horses suffering from severe colic.

Ischemic perconditioning on mesenteric ischemia/reperfusion injury in rats

Purpose:

To evaluate if the perconditioning affects the antioxidant capacity in mesenteric ischemia and reperfusion injury.

Methods:

Twenty-one Wistar rats were assigned into three groups, as follows: Sham, IR and rPER. The animals were subjected to mesenteric ischemia for 30 min. rPER consisted of three cycles of 5-min hindlimb ischemia followed by 5 min hindlimb perfusion at the same time to mesenteric ischemic period. After 5 minutes, blood and 5 cm of terminal ileum were harvested for thiobarbituric acid reactive substances (TBARS) and Trolox equivalent antioxidant capacity (TEAC) measurement.

Results:

rPER technique was able to reduce intestinal tissue TBARS levels (p<0.0001), but no statistic difference was observed in blood levels between groups, although it was verified similar results in rPER and Sham group. rPER technique also enhanced TEAC levels in both blood (p = 0.0314) and intestinal tissue (p = 0.0139), compared to IR group.

Conclusions:

rPER appears as the most promising technique to avoid IR injury. This technique reduced TBARS levels in blood and intestinal tissue and promoted the maintenance of antioxidant defense in mesenteric acute injury.

Anti-inflammatory and antioxidant effects of the nanocomposite Fullerol decrease the severity of intestinal inflammation induced by gut ischemia and reperfusion

Intestinal ischemia is a vascular emergency that arises when blood flow to the intestine is compromised. Reperfusion is necessary to restore intestinal function but might lead to local and systemic inflammatory responses and bacterial translocation, with consequent multiple organ dysfunction syndrome (MODS). During reperfusion occurs production of reactive oxygen species. These species contribute to intestinal injury through direct toxicity or activation of inflammatory pathways. Fullerol is a nanacomposite which has been shown to act as reactive oxygen species and reactive nitrogen species (RNS) scavengers. Thus, our aim was to evaluate whether Fullerol confer anti-inflammatory activity during intestinal ischemia and reperfusion (IIR). Intestinal ischemia was induced by total occlusion of the superior mesenteric artery. Groups were treated with vehicle or Fullerol 10 min before reperfusion. Mice were euthanized after 6 h of reperfusion, and small intestines were collected for evaluation of plasma extravasation, leukocyte influx, cytokine production and histological damage. Bacterial translocation to the peritoneal cavity and reactive oxygen and nitrogen species production by lamina propria cells were also evaluated. Our results showed that treatment with Fullerol inhibited bacterial translocation to the peritoneal cavity, delayed and decreased the lethality rates and diminished neutrophil influx and intestinal injury induced by IIR. Reduced severity of reperfusion injury in Fullerol-treated mice was associated with blunted reactive oxygen and nitrogen species production in leukocytes isolated from gut lamina propria and decreased production of pro-inflammatory mediators. Thus, the present study shows that Fullerol is a potential therapy to treat inflammatory bowel disorders associated with bacterial translocation, such as IIR.

Polydeoxyribonucleotide Exerts Therapeutic Effect by Increasing VEGF and Inhibiting Inflammatory Cytokines in Ischemic Colitis Rats

Ischemic colitis is resulted from an inadequate blood supply to a segment or entire colon. Polydeoxyribonucleotide (PDRN), extracted from salmon sperm, has been reported to exert anti-inflammatory and anti-ischemic effects through the adenosine A_2A receptor (A_2AR). We investigated whether PDRN possesses therapeutic effectiveness on ischemic colitis rats. Ischemic colitis was induced by selective devascularization. The skin temperature on the ischemic colitis-induced region was determined. To assess the colonic damage score and collagen deposition, colonic tissue sections were stained with hematoxylin and eosin (H&E), and Masson trichrome staining was performed. Western blot analysis for A_2AR, vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6, Bax, Bcl-2, and extracellular signal-regulated kinase 1/2 (ERK1/2) was performed. Skin temperature was increased and mucosal damage and collagen deposition were observed in the affected colonic tissues in the ischemic colitis rats. Expressions of inflammatory cytokines (TNF-α, IL-1β, and IL-6) and inflammatory mediator (COX-2) were upregulated in the ischemic colitis rats. Apoptosis was increased by decreasing the ratio of Bcl-2 to Bax and by suppressing the phosphorylated form of ERK1/2 expression in the ischemic colitis rats. Treatment with PDRN alleviated mucosal damage reduced the expressions of inflammatory cytokines and COX-2 and inhibited apoptosis in the ischemic colitis rats. PDRN treatment more enhanced the expressions of A_2AR and VEGF in the ischemic colitis rats. PDRN showed therapeutic effectiveness on ischemic colitis by increasing VEGF expression and inhibiting inflammatory cytokines and COX-2 through enhancing A_2AR expression.

Accelerated cell turnover 48 h after intestinal ischemia is NOTCH independent

AIM OF THE STUDY

Notch signaling plays important roles in maintaining intestinal epithelial homeostasis. When Notch signaling is blocked, proliferation ceases and epithelial cells become secretory. The purpose of the present study was to evaluate the role of Notch signaling pathway following intestinal ischemia-reperfusion (IR) injury in a rat model.

MATERIALS AND METHODS

Male Sprague-Dawley rats were randomly divided into four experimental groups: Sham-24 and Sham-48 rats underwent laparotomy and were killed 24 or 48 h later, respectively; IR-24 and IR-48 rats underwent occlusion of SMA and portal vein for 30 min followed by 24 or 48 h of reperfusion, respectively. Enterocyte proliferation and enterocyte apoptosis were determined at killing. Notch-related gene and protein expression were determined using Real Time PCR, Western blotting and immunohistochemistry 48 h followed IR.

MAIN RESULTS

IR-48 rats demonstrated significantly increased rates of cell proliferation and increased cell apoptosis in both jejunum and ileum compared to Sham rats. IR-48 rats exhibited a significant decrease in Notch-1 protein expression (Western blot) that was coincided with a significant decrease in the number of Notch-1 positive cells (immunohistochemistry) in jejunum (35% decrease, p < 0.05) and ileum (twofold decrease, p < 0.05) as well as Hes-1 positive cells in jejunum (28% decrease, p < 0.05) and ileum (31% decrease, p < 0.05) compared to Sham-48 rats.

CONCLUSIONS

Forty-eight hours following intestinal IR in rats, accelerated cell turnover was associated by inhibited Notch signaling pathway. Intestinal stem cells differentiation toward secretory progenitors rather than differentiation toward absorptive cells is important at this phase of intestinal recovery.

A glucocorticoid receptor agonist improves post-weaning growth performance in segregated early-weaned pigs

While beneficial for sow reproductive efficiency and biosecurity, segregated early weaning (SEW) leads to a systemic immune response that adversely affects the digestive physiology and post-weaning growth of pigs. Two experiments were conducted to evaluate the effects of a glucocorticoid receptor agonist (GA) on growth performance, measures of immune function and intestinal integrity of SEW pigs. In both experiments, pigs were fed corn-soybean meal-based starter diets. In the first experiment, 48 pigs (initial BW 4.8 ± 0.7 kg) were weaned at 21 ± 1 days and randomly assigned to three GA treatment groups: 0, 0.2 and 0.6 mg GA/kg of BW injected intramuscularly. Treatments were administered one day before weaning. Pigs in the 0 mg GA group received sterile saline in place of GA. Body weight was measured daily from one day before to 7 days post-weaning, and then weekly until 28 days post-weaning. Piglets treated with 0.2 mg GA had a higher BW than piglets in other treatment groups during the 28-day course of the study (P <0.02). To further explore the mechanisms behind this result, a second experiment was performed in which a total of 18 gilts (BW 5.6 ± 0.85 kg) were randomly assigned into three treatment groups: suckling plus saline (UWS), weaned treated with GA (WGA; 0.2 mg GA/kg BW) and weaned plus saline (CON). Treatments were administered one day before and 3 days post-weaning. The WGA and CON groups were weaned at 23 ± 2 days, while the UWS group remained with sow for the duration of the study. Body weight was measured daily and blood plasma was collected at 0, 1, 4 and 5 days post-weaning. All gilts were euthanized 5 days after weaning and jejunum samples were collected for mucosal scrapings, histomorphological analysis and gene expression analysis. Plasma levels of interleukin-1β (IL-1β) and haptoglobin were lower in WGA pigs compared with CON (P <0.02), while plasma total antioxidant capacity was higher in WGA pigs compared with both CON and UWS groups (P <0.01). Relative to CON, GA downregulated IL-18 gene expression in the jejunum, as assessed by both tissue homogenate and mucosal scrapings, but it upregulated claudin-IV gene expression only in the tissue homogenate (P <0.01). These results suggest that GA treatment improves the growth performance of SEW pigs in part by mitigating the negative effects of systemic inflammation. However, the effect of GA on barrier integrity requires further investigation.

Sonic hedgehog signaling controls gut epithelium homeostasis following intestinal ischemia-reperfusion in a rat

PURPOSE

One of the major regulators of gastrointestinal tract development is the hedgehog signaling pathway. The purpose of this study was to evaluate the role of sonic hedgehog (SHh) signaling 24 and 48 h following intestinal ischemia-reperfusion (IR) in a rat.

MATERIALS AND METHODS

Male rats were divided into four experimental groups: (1) Sham-24 h rats underwent laparotomy and were sacrificed after 24 h, (2) Sham-48h rats underwent laparotomy and were sacrificed after 48 h, (3) IR-24h rats underwent occlusion of both superior mesenteric artery and portal vein for 20 min followed by 24 h of reperfusion, and (4) IR-48 h rats underwent ischemia for 20 min followed by 48 h of reperfusion. Intestinal structural changes, enterocyte proliferation and enterocyte apoptosis were determined by immunohistochemistry 24 and 48 h following IR. SHh-related genes and protein expression were determined using real-time PCR, Western blot and immunohistochemistry.

RESULTS

IR-24 rats demonstrated a significant decrease in Shh, Ihh, GIL and Ptch2 mRNA in jejunum and ileum compared to Sham-24 animals that was accompanied by a significant decrease in the number of SHH-positive cells (Immunohistochemistry) in jejunum (2.5-fold decrease) and ileum (37%). After 48 h, IR rats demonstrated a significant increase in Dhh, Ihh, Gil and PTCH2 mRNA in jejunum as well as in Dhh, Ihh, SMO, GIL, PTCH2 mRNA in ileum compared to IR-24 animals that was coincided with increased number of SHH-positive cells in jejunum (2.6-fold increase) and ileum (1.4-fold increase).

CONCLUSIONS

24 h following intestinal IR, inhibited cell turnover was associated with inhibited SHh signaling pathway. Signs of intestinal recovery appeared 48 h after IR and were correlated with increase in SHh signaling pathway activity.

Sitagliptin attenuates intestinal ischemia/reperfusion injury via cAMP/PKA, PI3K/Akt pathway in a glucagon-like peptide 1 receptor-dependent manner

AIMS

This study investigated the effect of sitagliptin prophylactic treatment on intestinal I/R rat model and explored the possible underlying mechanism.

MAIN METHODS

Forty-five male Sprague-Dawley rats were randomly assigned to 3 groups: Sham group (operation without clamping), I/R group (operation with clamping) and sitagliptin pretreated group (300 mg/kg/day; p.o.) for 2 weeks before I/R insult. Intestinal I/R was performed by clamping the superior mesenteric artery for 30 min, followed by 60 min reperfusion after removal of clamping. At the end of the experimental period, all rats were sacrificed for histopathological, biochemical, PCR and western blot assessment.

KEY FINDINGS

Pretreatment with sitagliptin remarkably alleviated the pathological changes induced by I/R in the jejunum, suppressed upregulated NF-κB, TNF-α, IL-1βand MPO caused by I/R. Moreover, sitagliptin decreased the Bax/Bcl-2 ratio and accordingly suppressed apoptotic tissue damage as reflected by a caspase-3 level reduction in rat intestine subjected to I/R injury. Interestingly, sitagliptin could obviously increase the active GLP-1 level and GLP-1 receptor mRNA expression in the jejunum of I/R rats. This was associated with the augmentation of the cAMP level and enhancement of PKA activity. Simultaneously, sitagliptin treatment was able to increase the protein expression levels of phosphorylated PI3K and Akt.

SIGNIFICANCE

Sitagliptin has shown protective effects against intestinal I/R injury in rats through reduction of intestinal inflammation and apoptosis. The molecular mechanisms may be partially correlated with activation of cAMP/PKA and PI3K/Akt signaling pathway by the GLP-1/GLP-1 receptor.

Mechanism underlying methyl eugenol attenuation of intestinal ischemia/reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury is associated with a high risk of mortality in the clinical situation. Many factors are involved in I/R, including reactive oxygen species, cytokine release, and apoptosis. We aimed to determine whether a pure methyl eugenol (ME) given before intestinal ischemia, protects against intestinal I/R injury and the possible mechanism involved in this protection. Rat received ME (100 mg/kg) for 30 days then underwent intestinal I/R with 30 min ischemia and 60 min reperfusion. Serum lactate dehydrogenase (LDH) level, tissue malondialdehyde (MDA), as well as some antioxidant biomarkers were assessed, while the serum level of tumor necrosis factor alpha (TNF-α) was determined by ELISA. The change in TNF-α and interleukin 6 (IL-6) gene expressions were evaluated and confirmed by assessing protein level of TNF-α in the intestinal tissue by immunohistochemistry. Apoptosis was evaluated using DNA-laddering assay and by detecting caspase-3 immunohistochemically. Administration of ME prior to I/R injury resulted in a modulation of the production of MDA, LDH, and nitric oxide and restoration of the tested oxidative stress biomarkers. Pretreatment with ME downregulated messenger RNA of TNF-α and IL-6 inflammatory cytokines and their protein expressions in I/R rats. Marked inhibition of the apoptotic DNA and improvement of the architectures of small intestine were observed after pretreatment with ME. ME exhibits a protective effect against intestinal I/R via amelioration of the oxidative stress and inflammatory cytokines gene expression. Therefore, the supplementation of ME prior to intestinal I/R might be helpful in the attenuation of I/R complications.

Europium-Doped Cerium Oxide Nanoparticles Limit Reactive Oxygen Species Formation and Ameliorate Intestinal Ischemia-Reperfusion Injury

Accumulating evidence suggests that ischemia-reperfusion-induced injury is associated with the formation of reactive oxygen species (ROS). This study demonstrates the therapeutic effectiveness of novel europium-doped cerium oxide nanoparticles (Eu-doped Ceria NPs) as ROS scavengers in a mouse model of intestinal ischemia-reperfusion-induced injury. An increased production of superoxide radicals is detected in the intestine throughout the ischemia stage and again after initiating reperfusion. These changes in superoxide radical formation are associated with the induction of inflammatory cytokines in the intestine. This study further shows that Eu-Ceria NPs exhibit superoxide scavenging activity in vitro. Importantly, administration of Eu-Ceria NPs into the intestinal lumen during the onset of ischemia effectively blocks superoxide accumulation, reduces the expression of IL-1b, and ameliorates the intestinal pathology. These results suggest that early increased production of ROS during the ischemia-reperfusion promotes intestinal pathology and that mucosal delivery of Eu-Ceria NPs may be a potential therapeutic approach to block ROS accumulation and ameliorate the severity of intestinal disease.

Protective effects of hydrogen rich water on the intestinal ischemia/reperfusion injury due to intestinal intussusception in a rat model

This study aimed to investigate the protective effects of hydrogen rich water on the intestinal ischemia/reperfusion (I/R) injury in a rat intestinal intussusception (II) model. Ninety Sprague-Dawley rats were randomly assigned into three groups (n = 30 per group). In sham group, rats received laparotomy, and the intestine was exposed for 15 minutes without II. In I/R + saline group and I/R + hydrogen group, rats received II after laparotomy and then intestine was relocated 8 hours later, followed by immediately intraperitoneal injection of normal saline and hydrogen rich water (HRW) (5 mL/kg), respectively. One hour later, the intestine was collected for hematoxylin-eosin staining and immunohistochemistry for apoptotic cells and 8-oxo-deoxyguanosine, and blood was harvested for detection of tumor necrosis factor-α, malondialdehyde and superoxide dismutase. Hematoxylin-eosin staining showed the intestinal mucosa was significantly damaged in I/R + saline group, which was markedly attenuated after HRW treatment. The serum tumor necrosis factor-α content increased significantly in I/R + saline group, but HRW treatment reduced serum tumor necrosis factor-α content as compared to I/R + saline group (P < 0.05). Serum malondialdehyde content and 8-oxo-deoxyguanosine positive cells in the intestine increased dramatically after II, but HRW significantly reduced them in I/R+hydrogen group (P < 0.05). In addition, superoxide dismutase activity reduced markedly and apoptotic cells increased in I/R + saline group as compared to sham group, but they HRW increased superoxide dismutase activity and reduced apoptotic cells significantly in I/R + hydrogen group (P < 0.05). Our results indicate hydrogen rich water is able to attenuate II induced intestinal I/R injury via inhibiting intestinal inflammation, attenuating intestinal/serum oxidative stress and reducing apoptotic intestinal cells.

Green Tea Induced Cellular Proliferation and the Expression of Transforming Growth Factor-β1 in the Jejunal Mucosa of Fasting Rats

OBJECTIVE

The aim of this study was to understand whether or not the protective effect of green tea after fasting-induced damage in the jejunal mucosa of rat is dependent on cell proliferation and the stimulation of specific growth factors.

MATERIALS AND METHODS

Sixty adult male Wistar rats were used in this study. The animals were divided randomly into 5 groups, with 12 in each group (G1-5). The animals in G1 (control group) were fed a rat chow diet and water ad libitum. The animals in G2 (fasting group) were fasted for 3 days. The animals in the G3, G4, and G5 groups were fasted for 3 days as G2, but were given water (G3), green tea (G4), or a vitamin E (G5) solution, respectively, for another 7 days. The animals were euthanized, and the jejunum was removed and processed for histological and immunohistochemical analysis.

RESULTS

Compared to the G3 group, the jejunal mucosa of G4 rats showed a 70.6% higher level (p < 0.001) of expression of proliferating cell nuclear antigen and 98% higher level (p = 0.0001) of the expression of transforming growth factor-β1 (TGF-β1), whereas the level of fibroblast growth factor-1 (FGF-1) and insulin-like growth factor-1 (IGF-1) expression was 22 and 11% lower, respectively, in G4 animals as compared to G3 rats. These differences in the expression of FGF-1 and IGF-1 in G4 animals were not statistically significant.

CONCLUSION

In this study, green tea repaired the fasting-induced damage in the jejunal mucosa of rats, mainly by inducing a significant expression of TGF-β1 in the jejunal mucosa.

Fenofibrate reduces intestinal damage and improves intestinal recovery following intestinal ischemia-reperfusion injury in a rat

PURPOSE

Fenofibrate (FEN) is known as a nuclear receptor activator which regulates many pathophysiological processes, such as oxidative stress, inflammation, and leukocyte endothelium interactions. Recent studies have demonstrated an anti-oxidant, anti-inflammatory, and anti-ischemic role of FEN in the attenuation of ischemia-reperfusion (IR) injury in the kidney, liver, brain, and heart. The purpose of the present study was to examine the effect of FEN on intestinal recovery and enterocyte turnover after intestinal IR injury in rats.

METHODS

Male Sprague-Dawley rats were divided into four experimental groups: (1) sham rats underwent laparotomy, (2) sham-FEN rats underwent laparotomy and were treated with intraperitoneal (IP) FEN (20 mg/kg); (3) IR rats underwent occlusion of both the superior mesenteric artery and the portal vein for 30 min followed by 24 h of reperfusion, and (4) IR-FEN rats underwent IR and were treated with IP FEN immediately before abdominal closure. Intestinal structural changes, Park's injury score, enterocyte proliferation, and enterocyte apoptosis were determined 24 h following IR. The expression of Bax, Bcl-2, p-ERK, and caspase-3 in the intestinal mucosa was determined using real-time PCR, Western blot, and immunohistochemistry.

RESULTS

Treatment with FEN resulted in a significant decrease in Park's injury score in jejunum (32 %) and ileum (33 %) compared to IR animals. IR-FEN rats also demonstrated a significant increase in mucosal weight in jejunum (23 %) and ileum (22 %), mucosal DNA (38 %) and protein (65 %) in jejunum, villus height in jejunum (17 %) and ileum (21 %), and crypt depth in ileum (14 %) compared to IR animals. IR-FEN rats also experienced significant proliferation rates as well as lower apoptotic indices in jejunum and ileum which was accompanied with higher Bcl-2 levels compared to IR animals.

CONCLUSIONS

Treatment with fenofibrate prevents intestinal mucosal damage and stimulates intestinal epithelial cell turnover following intestinal IR in a rat model.

Semi-bionic extraction of compound turmeric protects against dextran sulfate sodium-induced acute enteritis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Compound turmeric has been widely used as a remedy for infectious diseases in China. It is a classic multi-herb prescription in traditional Chinese medicine, commonly used in the treatment of enteritis, pneumonia, and abdominal pain for hundreds of years. However, throughout this history, the powder of multi-herbs was directly swallowed, which is currently difficult to administer to patients. The extract of Chinese herbal medicine is made by semi-bionic extraction technology, which is great progress in the modernization of powders of traditional Chinese medicine. The aim of this work is to investigate the protective effects of semi-bionic extraction of compound turmeric (SET) on acute enteritis (AE) induced by dextran sulfate sodium (DSS) in rats.

MATERIALS AND METHODS

SET was extracted in artificial gastric juice or artificial intestinal juice and mixed. After vacuum drying, the SET powder was dissolved in distilled water. Adult male Sprague-Dawley rats were randomly divided into six groups. Rats were given salazosulfapyridine (SASP, 175.0mg/kg) or SET (0.42 or 0.21g/kg) before intragastric administration of 5% DSS solutions (0.75g/kg). The treatments lasted 7 days. The food intake in 24h, disease activity index (DAI), and wet/dry (W/D) weight ratios and histological changes in colon tissue were measured. The tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β, IL-8, and IL-10 in serum were determined at 1, 4, or 7 d after DSS challenge. Myeloperoxidase (MPO), malonaldehyde (MDA), diamine oxidase (DAO), and glutathione peroxidase (GSH-Px) activities in colon tissue were determined at 7 d. In addition, the nuclear factor-kappa (NF-κ B) and intercellular cell adhesion molecule-1 (ICAM-1) activations in colon tissue were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.

RESULTS

In rats with AE, SET significantly reduced DAI at 7 d after DSS treatment, increased the body weight of rats and the food intake in 24h at 3 or 6 d after DSS challenge, and reduced the colon W/D ratio. SET also reduced the TNF-α, IL-6, IL-1β, and IL-8 in serum and increased IL-10 in serum at 4 and 7 d. In addition, SET decreased MPO, MDA, DAO, and GSH-Px activities in colon and attenuated histological changes in the colon at 7 d after DSS treatment. Further studies demonstrated that SET significantly inhibited NF-κB and ICAM-1 activations in colon tissue.

CONCLUSIONS

The current study demonstrated that SET has potent protective effects on DSS-induced AE in rats through its anti-inflammatory and anti-oxidant activities.

Selenium Deficiency Attenuates Chicken Duodenal Mucosal Immunity via Activation of the NF-κb Signaling Pathway

Selenium (Se) deficiency can cause intestinal mucosal inflammation, which is related to activation of nuclear transcription factor kappa-B (NF-κB) signaling pathway. However, the mechanism of inflammatory response in chicken duodenal mucosa caused by Se deficiency and its relationship with the NF-κB signaling pathway remain elusive. In this study, we firstly obtained Se-deficient chickens bred with 0.01 mg/kg Se and the normal chickens bred with 0.4 mg/kg Se for 35 days. Then, NF-κB signaling pathway, secretory immunoglobulin A (SIgA), inflammatory cytokines, oxidized glutathione, glutathione peroxidase, and glutathione activities were determined. The results showed that Se deficiency obviously enhanced p50, p65, and p65 DNA-binding activities. The phosphorylation of IκB-α and phosphorylation of kappa-B kinase subunit alpha (IKKα) and IKKα were elevated, but IκB-α was decreased (P < 0.05). Moreover, Se deficiency reduced SIgA amount in the duodenal mucosa but increased the level of interleukin-1β (IL-1β), IL-17A, tumor necrosis factor-α (TNF-α), and interferon gamma (IFN-γ). In contrast, anti-inflammatory cytokines, such as TGF-β1 and IL-10, were significantly suppressed. Additionally, Se deficiency increased oxidized glutathione activity, whereas decreased glutathione peroxidase and glutathione activities (P < 0.05), suggesting that Se deficiency affected the regulation function of redox. Taken together, our results demonstrated that Se deficiency attenuated chicken duodenal mucosal immunity via activation of NF-κB signaling pathway regulated by redox activity, which suggested that Se is a crucial host factor involved in regulating inflammation.

Neutrophil proteomic analysis reveals the participation of antioxidant enzymes, motility and ribosomal proteins in the prevention of ischemic effects by preconditioning

Intestinal ischemia and reperfusion injury are widely used models, which result into tissue injury and multiple organ failure also observed after trauma and surgery. Ischemic preconditioning (IPC) preceding ischemia and reperfusion (IR) was shown to attenuate this injury and has a potential therapeutic application; however the exact underlying mechanism is not clear. Neutrophils play an important role in the mechanism of injuries caused by ischemia and reperfusion while IPC led to a decrease in neutrophil stimulation and activation. The effect of preconditioning on the neutrophil proteome is unclear. Proteomic analysis has been ratified as an appropriate tool for studying complex systems. In order to evaluate the effect of IPC preceding 45min of ischemia on the proteome of neutrophils we used Wistar rats divided in four experimental groups: Control, sham laparotomy, intestinal ischemia reperfusion and ischemic preconditioning. After neutrophil separation, proteins were extracted, trypsin digested and the resulting peptides were iTRAQ labeled followed by HILIC fractionation and nLC-MS/MS analysis. After database searches, normalization and statistical analysis our proteomic analysis resulted in the identification of 2437 protein groups that were assigned to five different clusters based on the relative abundance profiles among the experimental groups. The clustering followed by statistical analysis led to the identification of significantly up and downregulated proteins in IR and IPC. Cluster based KEGG pathways analysis revealed up- regulation of actin cytoskeleton, metabolism, Fc gamma R mediated phagocytosis, chemokine signaling, focal adhesion and leukocyte transendothelial migration whereas downregulation in ribosome, spliceosome, RNA transport, protein processing in endoplasmic reticulum and proteasome, after intestinal ischemic preconditioning. Furthermore, enzyme prediction analysis revealed the regulation of some important antioxidant enzymes and having their role in reactive oxygen species production. To our knowledge, this work describes the most comprehensive and detailed quantitative proteomic study of the neutrophil showing the beneficial role of ischemic preconditioning and its effects on the neutrophil proteome. This data will be helpful to understand the effect of underlying protective mechanisms modulating the role of PMNs after IPC and provide a trustworthy basis for future studies.

BIOLOGICAL SIGNIFICANCE

Preconditioning is a relevant strategy to overcome clinical implications from ischemia and reperfusion. Such implications have the neutrophil as a major player. Although many publications describe specific biochemical and physiological roles of the neutrophil in such conditions, there is no report of a proteomic study providing a broader view of this scenario. Here we describe a group of proteins significantly regulated by ischemia and reperfusion being such regulation prevented by preconditioning. Such finding may provide relevant information for a deeper understanding of the mechanisms involved, as well as serve as basis for future biomarker or drug target assays.

The Gastrointestinal Circulation: Physiology and Pathophysiology

The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.

Antioxidant Potential of the Methanol Extract of Parquetina nigrescens Mediates Protection Against Intestinal Ischemia-Reperfusion Injury in Rats

Parquetina nigrescens is a medicinal herb with recognized antioxidant properties and potential to alleviate conditions associated with oxidative stress, including gastric ulcers. We investigated the protective potential of methanol extract of Parquetina nigrescens (MEPN) against ischemia-reperfusion injury in the intestine of rats. Thirty (30) male Wistar albino rats were randomly assigned into five groups with Group I made up of control rats and Group II consisting of rats experimentally subjected to ischemia and reperfusion (IR) by clamping of the superior mesenteric artery (SMA) for 30 minutes and 45 minutes, respectively. Groups III and IV rats also had IR, but were initially pre-treated with MEPN at 500 mg/kg and 1000 mg/kg respectively, for seven days. Rats in Group V were also pre-treated with Vitamin C, for seven days, before induction of IR. The results showed marked reduction in intestinal epithelial lesions in groups treated with MEPN, compared to the IR group which had severe villi erosion, inflammatory cell infiltration and hemorrhages. There were significant increases in Malondialdehyde (MDA) and significant reductions in reduced glutathione (GSH) and Glutathione S-transferase (GST) activity with IR injury, while pre-treatment with either MEPN or Vitamin C prevented these effects. Increases in Glutathione peroxidase (GPX), Catalase (CAT) and Superoxide dismutase (SOD) with IR provided evidence for adaptive responses to oxidative injury during IR and preservation of enzyme activity by MEPN and Vitamin C. Taken together, Parquetina nigrescens provided considerable alleviation of intestinal injury produced by IR, at values much as effective as that offered by Vitamin C.

Protective Effect of Peroxiredoxin 6 in Ischemia/Reperfusion-Induced Damage of Small Intestine

BACKGROUND

Strong oxidative stress starting in the epithelium upon restoration of blood cell circulation is a major cause of necrosis of the intestinal epithelium in ischemia/reperfusion-induced damage.

AIM

The purpose of this study was to investigate the tissue-protective effect of exogenous peroxiredoxin 6 (Prx6) in ischemia/reperfusion-induced damage of small intestine.

METHODS

The research was carried out using a model of acute superior mesenteric artery occlusion in Wistar male rats. Exogenous Prx6 was administrated intravenously 15 min prior to small intestine ischemia. The distribution of endogenous Prx6 in the small intestine was determined by immunohistochemical analysis. The expression level of antioxidant enzymes was evaluated by RT-PCR in real time.

RESULTS

Exogenous Prx6 injected to animals intravenously was detected in blood vessel lumens, and its diffuse distribution was subsequently confirmed in the intestinal epithelium. Expression analysis of genes coding for major antioxidant enzymes demonstrated a significant activation of SOD 1, SOD 3, Prx6, GPx2, GPx7 expression during I/R-induced damage of the small intestine. Injection of exogenous Prx6 prior to induced ischemia resulted in minimization of oxidative injury by reducing necrosis and apoptosis, by normalization of gene activity of antioxidant enzyme. It eventually led to a reduction of epithelium destruction in the small intestine. By contrast, administration of a purified mutant form of Prx6 (Prx6C47S) without peroxidase activity had no protective effect.

CONCLUSION

The application of exogenous Prx6 enables normalization of the antioxidant status of the small intestine and reduction of cell destruction upon I/R-induced organ damage.

The Human Colon Is More Resistant to Ischemia-reperfusion-induced Tissue Damage Than the Small Intestine: An Observational Study

OBJECTIVE

Aim of this study was to draw comparisons between human colonic and jejunal ischemia-reperfusion sequelae in a human in vivo experimental model.

BACKGROUND

In patients, colonic ischemia-reperfusion generally has a milder course than small intestinal ischemia-reperfusion. It is unclear which pathophysiologic processes are responsible for this difference.

METHODS

In 10 patients undergoing colonic surgery and 10 patients undergoing pancreaticoduodenectomy, 6 cm colon or jejunum was isolated and exposed to 60 minutes ischemia followed by various reperfusion periods. Morphology (hematoxylin and eosin), apoptosis (M30), tight junctions (zonula occludens 1), and neutrophil influx (myeloperoxidase) were assessed using immunohistochemistry. Quantitative polymerase chain reaction and enzyme-linked immunosorbent assay were performed for interleukin-6 and tumor necrosis factor-α.

RESULTS

Hematoxylin and eosin staining revealed intact colonic epithelial lining, but extensive damage in jejunal villus tips after 60 minutes ischemia. After reperfusion, the colonic epithelial lining was not affected, whereas the jejunal epithelium was seriously damaged. Colonic apoptosis was limited to scattered cells in surface epithelium, whereas apoptosis was clearly observed in jejunal villi and crypts, (42 times more M30 positivity compared with colon, P < 0.01). Neutrophil influx and increased tumor necrosis factor-α mRNA expression were observed in jejunum after 30 and 120 minutes of reperfusion (P < 0.05). Interleukin-6 mRNA expression was increased in jejunum after 120 minutes of reperfusion (3.6-fold increase, P < 0.05), whereas interleukin-6 protein expression was increased in both colon (1.5-fold increase, P < 0.05) and small intestine (1.5-fold increase, P < 0.05) after 30 and 120 minutes of reperfusion.

CONCLUSIONS

Human colon is less susceptible to IR-induced tissue injury than small intestine.

Higenamine regulates Nrf2-HO-1-Hmgb1 axis and attenuates intestinal ischemia-reperfusion injury in mice

INTRODUCTION

Intestinal ischemia and reperfusion (IR) syndrome is a life-threatening dilemma caused by diverse events. Higenamine (HG), an active ingredient of Aconiti Lateralis Radix Praeparata, has been traditionally used as a heart stimulant and anti-inflammatory agent in oriental countries. But the function of HG on intestine IR injury has never been investigated.

MATERIALS AND METHODS

Mice underwent a 2 cm midline laparotomy, and the superior mesenteric artery (SMA) was obstructed by micro-vascular clamp to induce intestinal ischemia.

RESULTS

In our current study, HG increases mouse intestinal epithelial (IEC-6) cell viability through induced heme oxygenase-1 (HO-1) production in vitro. In our in vivo murine intestinal IR injury model, the increased HO-1 protein level and activity, decreased intestinal injury score, Myeloperoxidase (MPO) activity, and inflammatory cytokine expression induced by HG were all abolished with additional treatment of HO-1 inhibitor zinc protoporphyrin IX (ZnPPIX). Furthermore, HG reduced high mobility group box-1 (Hmgb1) expression in IR injury-performed intestine which was inhibited by additional administration of ZnPPIX. And HG treatment significantly decreased HO-1 expression in nuclear factor erythroid 2-related factor (Nrf-2) SiRNA-transfected cells but not in control SiRNA-transfected cells.

CONCLUSION

Our study provides evidence HG regulates Nrf2-HO-1-Hmgb1 axis and attenuates intestinal IR injury in mice.

Evaluation of the effects of ischemic preconditioning on the hematological parameters of rats subjected to intestinal ischemia and reperfusion

OBJECTIVES

Intestinal ischemia/reperfusion often leads to acute lung injury and multiple organ failure. Ischemic preconditioning is protective in nature and reduces tissue injuries in animal and human models. Although hematimetric parameters are widely used as diagnostic tools, there is no report of the influence of intestinal ischemia/reperfusion and ischemic preconditioning on such parameters. We evaluated the hematological changes during ischemia/reperfusion and preconditioning in rats.

METHODS

Forty healthy rats were divided into four groups: control, laparotomy, intestinal ischemia/reperfusion and ischemic preconditioning. The intestinal ischemia/reperfusion group received 45 min of superior mesenteric artery occlusion, while the ischemic preconditioning group received 10 min of short ischemia and reperfusion before 45 min of prolonged occlusion. A cell counter was used to analyze blood obtained from rats before and after the surgical procedures and the hematological results were compared among the groups.

RESULTS

The results showed significant differences in hematimetric parameters among the groups. The parameters that showed significant differences included lymphocyte, white blood cells and granulocyte counts; hematocrit; mean corpuscular hemoglobin concentration; red cell deviation width; platelet count; mean platelet volume; plateletcrit and platelet distribution width.

CONCLUSION

The most remarkable parameters were those related to leukocytes and platelets. Some of the data, including the lymphocyte and granulocytes counts, suggest that ischemic preconditioning attenuates the effect of intestinal ischemia/reperfusion on circulating blood cells. Our work contributes to a better understanding of the hematological responses after intestinal ischemia/reperfusion and IPC, and the present findings may also be used as predictive values.

Protective effects of terminal ileostomy against bacterial translocation in a rat model of intestinal ischemia/reperfusion injury

AIM: To investigate the effects of terminal ileostomy on bacterial translocation (BT) and systemic inflammation after intestinal ischemia/reperfusion (I/R) injury in rats.

METHODS: Thirty-two rats were assigned to either the sham-operated group, I/R group, I/R + resection and anastomosis group, or the I/R + ileostomy group. The superior mesenteric artery was occluded for 60 min. After 4 h, tissue samples were collected for analysis. BT was assessed by bacteriologic cultures, intestinal permeability and serum levels of endotoxin; systemic inflammation was assessed by serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10, as well as by the activity of myeloperoxidase (MPO) and by intestinal histopathology.

RESULTS: Intestinal I/R injury not only caused morphologic damage to ileal mucosa, but also induced BT, increased MPO activity and promoted the release of TNF-α, IL-6, and IL-10 in serum. BT and ileal mucosa injuries were significantly improved and levels of TNF-α and IL-6 in serum were decreased in the I/R + ileostomy group compared with the I/R + resection and anastomosis group.

CONCLUSION: Terminal ileostomy can prevent the detrimental effects of intestinal I/R injury on BT, intestinal tissue, and inflammation.

Antioxidant and anti-inflammatory effects of selenium in oral buccal mucosa and small intestinal mucosa during intestinal ischemia-reperfusion injury

Background

The aim of this study were to investigate whether selenium treatment attenuates lipid peroxidation and downregulates the NF-κB pathway in small intestinal mucosa and to examine whether the effect of selenium is also observed in oral buccal mucosa, during small intestinal IR injury.

Materials and methods

Eighteen rats were assigned into three groups: sham, IR, and IR + selenium. Saline or selenium was administered through a tail vein. 24 hours later, the superior mesenteric artery was exposed and clamped in the IR and IR + selenium groups. After ischemic and reperfusion period, animals were sacrificed and oral buccal mucosa and small intestinal mucosa were harvested.

Results

Glutathione peroxidase activity and cytoplasmic IκB-α expression was higher in the IR + selenium group than that in the IR group. A malondialdehyde level, cytoplasmic phosphorylated inhibitor κB-α, nuclear NF-κB p65 expressions, and NF-κB p65 DNA-binding activity were lower in the IR + selenium group than those in the IR group.

Conclusion

A selenium treatment may cause increased GPx activity, attenuated lipid peroxidation, and downregulated the NF-κB pathway during small intestinal IR injury. Furthermore, these therapeutic benefits of selenium can be observed in oral buccal mucosa as well as small intestinal mucosa.

Urinary Trypsin Inhibitor Ameliorates Seawater Immersion-Induced Intestinal Mucosa Injury via Antioxidation, Modulation of NF-κB Activity, and Its Related Cytokines in Rats with Open Abdominal Injury

Objective. To investigate the role of oxidative stress, NF-κB activity, and its related cytokines in the pathogenesis of seawater immersion after open abdominal injury (SI-OAI) and whether UTI treatment can attenuate SI-OAI induced IMI. Methods. Wistar rats were randomly divided into three groups: C group, S group, and U group. The rats in C group only suffered from anesthesia and surgical operation, whereas the rats in S group and U group received caudal vein injection of normal saline without/with 50,000 U/kg body weight of UTI. The activities of TNF-α, IL-6, SOD, MDA, ROS, NF-κB, and IκB-β were monitored by ELISA, biochemical methods, EMSA, and Western blot, respectively. Results. The plasma inflammatory mediators and the contents of MDA, ROS, and NF-κB in intestine as well as the pathological scores in ileal mucosa were significantly increased in rats after SI-OAI, accompanied by a reduction in SOD activities and IκB-β levels. UTI treatment significantly attenuated intestinal histopathological changes with evidence of a decrease in all of the parameters, except for upregulation of the levels of SOD and IκB-β protein. Conclusion. UTI can attenuate SI-OAI induced IMI via inhibition of NF-κB activity, subsequently inhibiting the expression of inflammatory cytokines and by combating oxidative stress.

Ischemic preconditioning in different times and its effect on bacterial translocation induced by intestinal ischemia and reperfusion in rats

OBJECTIVE

To evaluate the effects of different times of ischemic preconditioning (IPC) on intestinal bacterial translocation (BT).

METHODS

Thirty Wistar rats weighing 280 ± 27 g were divided into five groups. In the IR group (n = 6), laparotomy was performed and the superior mesenteric artery was occluded by an atraumatic microclamp for 30 minutes. In the four preconditioning groups (n = 6 each) before the 30 minutes of ischemia-reperfusion (I/R) rats underwent IPC for two, five, ten and 15 minutes, followed by the same time of reperfusion. In order to assess whether the time of preconditioning influenced the onset of bacterial translocation, samples of mesenteric lymph nodes, liver and spleen were collected in sterile conditions twenty-four hours after the procedures for quantification of bacterial colony forming units per gram of tissue (CFU/g). Blood was collected for measurement of cytokines.

RESULTS

In the I/R group, the total CFU/g in mesenteric lymph nodes, spleen, liver, as well as the serum TNF-á, IL-1â and IL-6 were significantly higher than in the other groups (p <0.05). Preconditioning for 15 minutes significantly attenuated BT and serum cytokines when compared to other periods of preconditioning (p <0.05).

CONCLUSION

Our data suggest preconditioning as a key factor to reduce bacterial translocation in intestinal I/R. On a scale of two to 15 minutes, the best time of ischemic preconditioning for the attenuation of bacterial translocation was 15 minutes.

Effect of ozone on intestinal recovery following intestinal ischemia-reperfusion injury in a rat

BACKGROUND

Growing evidence suggests that ozone (O3) protects the host against pathological conditions mediated by reactive oxygen species by increasing the activity of antioxidant enzymes. The purpose of the present study was to examine the effect of O3 on intestinal recovery and enterocyte turnover after intestinal ischemia-reperfusion (IR) injury in rats.

METHODS

Male Sprague-Dawley rats were divided into four experimental groups: (1) sham rats underwent laparotomy; (2) sham-O3 rats underwent laparotomy and were treated with an ozone/oxygen mixture intraperitoneally and intraluminally (50 %/50 %); (3) IR rats underwent occlusion of both superior mesenteric artery and portal vein for 20 min followed by 48 h of reperfusion, and (4) IR-O3 rats underwent IR and were treated with an ozone/oxygen mixture similar to group 2. Intestinal structural changes, Park's injury score, enterocyte proliferation and enterocyte apoptosis were determined 48 h following IR. Western blot was used to determine ERK and Bax protein levels. A non-parametric Kruskal-Wallis ANOVA test was used for statistical analysis with p < 0.05 considered statistically significant.

RESULTS

Treatment of IR rats with O3 resulted in a significant increase in mucosal weight in jejunum (70 %) and ileum (32 %), mucosal DNA (twofold increase) and protein (35 %) in ileum, villus height and crypt depth in jejunum (61 and 16 %, correspondingly) and ileum (31 and 43 %, correspondingly) compared to IR animals. IR-O3 rats also had a significantly lower intestinal injury score as well as a lower apoptotic index in jejunum and ileum compared and IR animals. A significant increase in cell proliferation rates in IR-O3 animals was accompanied by increased levels of p-ERK protein.

CONCLUSIONS

Treatment with ozone prevents intestinal mucosal damage, stimulates cell proliferation and inhibits programmed cell death following intestinal IR in a rat.

Dexamethasone pretreatment alleviates intestinal ischemia-reperfusion injury

BACKGROUND

Activated mast cells are involved in the pathogenesis of intestinal ischemia-reperfusion (I/R)-related injury. Dexamethasone has been widely used to protect organs from I/R injury. This study was conducted to investigate the impact of treatment with dexamethasone at different stages of the II/R process on mast cell infiltration and activity and intestinal injury.

METHODS

Kunming mice were randomized and subjected to a sham surgery or the II/R induction by clamping the superior mesenteric artery for 30 min and then reperfusion. During the II/R induction, the mice were treated intravenously with dexamethasone (10 mg/kg) for 30 min before ischemia (pretreatment group), at 5 min after clamping the superior mesenteric artery (isc-treatment group), or at the beginning of perfusion (rep-treatment group), respectively. The levels of intestinal injury, mast cell infiltration and activity, tumor necrosis factor α (TNFα) and myeloperoxidase (MPO) activity in the intestines, and mouse survival rates were measured.

RESULTS

The death rates, levels of intestinal injury, mast cell infiltration and activity, and tumor necrosis factor α and myeloperoxidase activity in the intestinal tissues from the II/R group were similar to those from the isc-treatment and rep-treatment groups of mice and were significantly higher than those from the sham group. In contrast, pretreatment with dexamethasone significantly mitigated the II/R-induced mast cell infiltration and activity, inflammation, and intestinal injury and reduced the death rates in mice.

CONCLUSIONS

Pretreatment with dexamethasone inhibits II/R injury by reducing mast cell-related inflammation in mice.

The jagged-2/notch-1/hes-1 pathway is involved in intestinal epithelium regeneration after intestinal ischemia-reperfusion injury

Background

Notch signaling plays a critical role in the maintenance of intestinal crypt epithelial cell proliferation. The aim of this study was to investigate the role of Notch signaling in the proliferation and regeneration of intestinal epithelium after intestinal ischemia reperfusion (I/R) injury.

Methods

Male Sprague-Dawley rats were subjected to sham operation or I/R by occlusion of the superior mesenteric artery (SMA) for 20 min. Intestinal tissue samples were collected at 0, 1, 2, 4, and 6 h after reperfusion. Proliferation of the intestinal epithelium was evaluated by immunohistochemical staining of proliferating nuclear antigen (PCNA). The mRNA and protein expression levels of Notch signaling components were examined using Real-time PCR and Western blot analyses. Immunofluorescence was also performed to detect the expression and location of Jagged-2, cleaved Notch-1, and Hes-1 in the intestine. Finally, the γ-secretase inhibitor DAPT and the siRNA for Jagged-2 and Hes-1 were applied to investigate the functional role of Notch signaling in the proliferation of intestinal epithelial cells in an in vitro IEC-6 culture system.

Results

I/R injury caused increased intestinal crypt epithelial cell proliferation and increased mRNA and protein expression of Jagged-2, Notch-1, and Hes-1. The immunofluorescence results further confirmed increased protein expression of Jagged-2, cleaved Notch-1, and Hes-1 in the intestinal crypts. The inhibition of Notch signaling with DAPT and the suppression of Jagged-2 and Hes-1 expression using siRNA both significantly inhibited the proliferation of IEC-6 cells.

Conclusion

The Jagged-2/Notch-1/Hes-1 signaling pathway is involved in intestinal epithelium regeneration early after I/R injury by increasing crypt epithelial cell proliferation.

Temporal relationship of serum markers and tissue damage during acute intestinal ischemia/reperfusion

OBJECTIVE

It is essential to identify a serological marker of injury in order to study the pathophysiology of intestinal ischemia reperfusion. In this work, we studied the evolution of several serological markers after intestinal ischemia reperfusion injury in rats. The markers of non-specific cell damage were aspartate aminotransferase, alanine aminotransaminase, and lactic dehydrogenase, the markers of inflammation were tumor necrosis factor alpha, interleukin-6, and interleukin-1 beta, and the markers of intestinal mucosal damage were intestinal fatty acid binding protein and D-lactate. We used Chiús classification to grade the histopathological damage.

METHODS

We studied 35 Wistar rats divided into groups according to reperfusion time. The superior mesenteric artery was clamped for 30 minutes, and blood and biopsies were collected at 1, 3, 6, 12, 24, and 48 hours after reperfusion. We plotted the mean ± standard deviation and compared the baseline and maximum values for each marker using Student's t-test.

RESULTS

The maximum values of interleukin-1 beta and lactic dehydrogenase were present before the maximal histopathological damage. The maximum tumor necrosis factor alpha and D-lactate expressions coincided with histopathological damage. Alanine aminotransaminase and aspartate aminotransferase had a maximum expression level that increased following the histopathological damage. The maximum expressions of interluken-6 and intestinal fatty acid binding protein were not significantly different from the Sham treated group.

CONCLUSION

For the evaluation of injury secondary to acute intestinal ischemia reperfusion with a 30 minute ischemia period, we recommend performing histopathological grading, quantification of D-lactate, which is synthesized by intestinal bacteria and is considered an indicator of mucosal injury, and quantification of tumor necrosis factor alpha as indicators of acute inflammation three hours after reperfusion.

Heme oxygenase-1 and gut ischemia/reperfusion injury: A short review

Ischemia/reperfusion (I/R) injury of the gut is a significant problem in a variety of clinical settings and is associated with a high morbidity and mortality. Although the mechanisms involved in the pathogenesis of gut I/R injury have not been fully elucidated, it is generally believed that oxidative stress with subsequent inflammatory injury plays an important role. Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme, followed by production of CO, biliverdin, and free iron. The HO system is believed to confer cytoprotection by inhibiting inflammation, oxidation, and apoptosis, and maintaining microcirculation. HO-1, an inducible form of HO, serves a vital metabolic function as the rate-limiting step in the heme degradation pathway, and affords protection in models of intestinal I/R injury. HO-1 system is an important player in intestinal I/R injury condition, and may offer new targets for the management of this condition.

Lycium barbarum polysaccharides reduce intestinal ischemia/reperfusion injuries in rats

Inflammation and oxidative stress exert important roles in intestinal ischemia-reperfusion injury (IRI). Lycium barbarum polysaccharides (LBPs) have shown effective antioxidative and immunomodulatory functions in different models. The purpose of the present study was to assess the effects and potential mechanisms of LBPs in intestinal IRI. Several free radical-generating and lipid peroxidation models were used to assess the antioxidant activities of LBPs in vitro. A common IRI model was used to induce intestinal injury by clamping and unclamping the superior mesenteric artery in rats. Changes in the malondialdehyde (MDA), tumor necrosis factor (TNF)-α, activated nuclear factor (NF)-κB, intracellular adhesion molecule (ICAM)-1, E-selectin, and related antioxidant enzyme levels, polymorphonuclear neutrophil (PMN) accumulation, intestinal permeability, and intestinal histology were examined. We found that LBPs exhibited marked inhibitory action against free radicals and lipid peroxidation in vitro. LBPs increased the levels of antioxidant enzymes and reduced intestinal oxidative injury in animal models of intestinal IRI. In addition, LBPs inhibited PMN accumulation and ICAM-1 expression and ameliorated changes in the TNF-α level, NF-κB activation, intestinal permeability, and histology. Our results indicate that LBPs treatment may protect against IRI-induced intestinal damage, possibly by inhibiting IRI-induced oxidative stress and inflammation.

Function and expression of cystic fibrosis transmembrane conductance regulator after small intestinal transplantation in mice

The secretion function of intestinal graft is one of the most important factors for successful intestinal transplantation. Cystic fibrosis transmembrane conductance regulator (CFTR) mediates HCO₃^- and Cl^- secretions in intestinal epithelial cells. In this study, we made investigation on the expression and function of CFTR in an experimental model of murine small intestinal transplantation. Heterotopic intestinal transplantations were performed in syngeneic mice. The mRNA and protein expressions of CFTR were analyzed by real time PCR and western blot. Murine intestinal mucosal HCO₃^- and Cl^- secretions were examined in vitro in Ussing chambers by the pH stat and short circuit current (I_sc) techniques. The results showed that forskolin, an activator of CFTR, stimulated jejunal mucosal epithelial HCO₃^- and Cl^- secretions in mice, but forskolin-stimulated HCO₃^- and Cl^- secretions in donor and recipient jejunal mucosae of mice after heterotopic jejunal transplantation were markedly decreased, compared with controls (P<0.001). The mRNA and protein expression levels of CFTR in donor and recipient jejunal mucosae of mice were also markedly lower than those in controls (P<0.001), and the mRNA and protein expression levels of tumor necrosis factor α (TNFα) were markedly increased in donor jejunal mucosae of mice (P<0.001), compared with controls. Further experiments showed that TNFα down-regulated the expression of CFTR mRNA in murine jejunal mucosa. In conclusion, after intestinal transplantation, the function of CFTR was impaired, and its mRNA and protein expressions were down-regulated, which may be induced by TNFα.

Bifidobacteria may be beneficial to intestinal microbiota and reduction of bacterial translocation in mice following ischaemia and reperfusion injury

The aim of the present study was to determine the effect of peroral bifidobacteria on the intestinal microbiota, barrier function and bacterial translocation (BT) in a mouse model of ischaemia and reperfusion (I/R) injury. A total of twenty-four male BALB/c mice were randomly allocated into three groups: (1) sham-operated, (2) I/R and (3) I/R injury and bifidobacteria pretreatment (109 colony-forming units/d). Bifidobacteria were administered daily intragastrically for 2 weeks before induction of I/R. Subsequently, samples of caecal content, intestinal mucosa, ileal segments, blood, mesenteric lymph nodes (MLN) and distant organs (liver, spleen and kidney) were prepared for examination. In the I/R model, barrier dysfunction (caecal microbiota dysbiosis, disruption of tight junction (TJ), increased epithelial cell apoptosis, disruption of mucosa and multiple erosions) in the intestine was observed, associated with increased BT to extraintestinal sites. The ratio of BT to MLN and distant organs in mice exposed to I/R injury was 62·5 %, which was significantly higher than the sham-operated group. However, pretreatment of animals with bifidobacteria prevented I/R-induced BT, reduced pro-inflammatory cytokine release, the levels of endotoxin, intestinal epithelial cell apoptosis, disruption of TJ and increased the concentration of SCFA, resulting in recovered microbiota and mucosal integrity. Bifidobacteria may be beneficial in reducing BT in I/R injury of mice. Therefore, peroral administration of bifidobacteria is a potential strategy to prevent I/R-induced BT and intestinal barrier dysfunction.

Suppressive effect of low-level laser therapy on tracheal hyperresponsiveness and lung inflammation in rat subjected to intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion (i-I/R) is an insult associated with acute respiratory distress syndrome (ARDS). It is not known if pro- and anti-inflammatory mediators in ARDS induced by i-I/R can be controlled by low-level laser therapy (LLLT). This study was designed to evaluate the effect of LLLT on tracheal cholinergic reactivity dysfunction and the release of inflammatory mediators from the lung after i-I/R. Anesthetized rats were subjected to superior mesenteric artery occlusion (45 min) and killed after clamp release and preestablished periods of intestinal reperfusion (30 min, 2 or 4 h). The LLLT (660 nm, 7.5 J/cm(2)) was carried out by irradiating the rats on the skin over the right upper bronchus for 15 and 30 min after initiating reperfusion and then euthanizing them 30 min, 2, or 4 h later. Lung edema was measured by the Evans blue extravasation technique, and pulmonary neutrophils were determined by myeloperoxidase (MPO) activity. Pulmonary tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), intercellular adhesion molecule-1 (ICAM-1), and isoform of NO synthase (iNOS) mRNA expression were analyzed by real-time PCR. TNF-α, IL-10, and iNOS proteins in the lung were measured by the enzyme-linked immunoassay technique. LLLT (660 nm, 7.5 J/cm(2)) restored the tracheal hyperresponsiveness and hyporesponsiveness in all the periods after intestinal reperfusion. Although LLLT reduced edema and MPO activity, it did not do so in all the postreperfusion periods. It was also observed with the ICAM-1 expression. In addition to reducing both TNF-α and iNOS, LLLT increased IL-10 in the lungs of animals subjected to i-I/R. The results indicate that LLLT can control the lung's inflammatory response and the airway reactivity dysfunction by simultaneously reducing both TNF-α and iNOS.

Mesenteric ischemia-reperfusion injury: specific impact on different cell populations within the jejunal wall in rats

The progress of jejunal damage and recovery in the course of mesenteric ischemia-reperfusion injury in rats at different time periods was investigated. Mesenteric ischemia lasting 1h followed by 1h of reperfusion caused a significant disintegration of the mucosa, reduction of the muscular layer and diminution of the wall thickness. The loss of epithelium included enterocytes, goblet cells and Paneth cells. Paradoxically, increasing numbers of serotonin-producing cells and the beginning of regenerative processes, expressed by significantly higher proliferation, were recorded in the epithelium during this period. Disintegration of connective tissue and massive degranulation of serotonin-positive cells were found in the lamina propria. After 24h of reperfusion, restitution of the mucosa was found, expressed by normal villous morphology and re-epithelialization. However, some parameters were still significantly affected even more than in the acute phase of reperfusion. In the epithelium, decreased numbers of Paneth cells and increased population of serotonin-producing cells were found. The greatest proliferation of connective tissue cells and intensified reduction of the muscular layer were also detected in this reperfusion period. After 30 days of reperfusion, moderate damage remained, but only the increased number of Paneth cells and decreased number of serotonin-producing cells in the lamina propria were significant.

Role of high mobility group box chromosomal protein 1 in ischemia-reperfusion injury in the rat small intestine

BACKGROUND

High mobility group box chromosomal protein 1 (HMGB1) has recently been shown to be an important late mediator of endotoxic shock and sepsis. The purpose of the present study was to investigate the role of HMGB1 in response to ischemia-reperfusion injury.

METHODS

Ischemia-reperfusion injury was induced in male Wistar rats by clamping the superior mesenteric artery for 60 min. Using this model, the serum concentrations and localization of HMGB1 were investigated. The histologic findings from reperfused intestines and the survival rates were compared between the anti-HMGB1 antibody treatment groups (group A treated with 6.0 mg/kg antibody and group B with 0.6 mg/kg antibody) and the control antibody treatment group (control group).

RESULTS

Serum HMGB1 concentrations increased early after reperfusion and peaked at 3 h. Immunohistochemistry for HMGB1 revealed a high degree of positive staining in the epithelial cells of the damaged villi. Anti-HMGB1 antibody treatment significantly reduced this damage (P < 0.05) and improved the 48-h survival rate (90% in group A versus 50% in the controls; P < 0.05).

CONCLUSIONS

These results suggest that HMGB1 plays a key role in small intestinal ischemia-reperfusion injury.