Mesenteric Ischemia-reperfusion Injury Research Articles

Plasma riboflavin fluorescence as a diagnostic marker of mesenteric ischemia-reperfusion injury in rats

Due to the delayed and vague symptoms, it is difficult to early diagnose mesenteric ischemia injuries in the dynamics of acute illness, leading to a 60–80 % mortality rate. Here, we found plasma fluorescence spectra can rapidly assess the severity of mesenteric ischemia injury in animal models. Ischemia-reperfusion damage of the intestine leads to multiple times increase in NADH, flavins, and porphyrin auto-fluorescence of blood. The fluorescence intensity ratio between blue-fluorophores and flavins can reflect the occurrence of shock. Using liquid chromatography and mass spectroscopy, we confirm that riboflavin is primarily responsible for the increased flavin fluorescence. Since humans absorb riboflavin from the intestine, its increase in plasma may indicate intestinal mucosa injury. Our work suggests a self-calibrated and reagent-free approach to identifying the emergence of fatal mesenteric ischemia in emergency departments or intensive care units.

Albendazole ameliorates inflammatory response in a rat model of acute mesenteric ischemia reperfusion injury

BackgroundAcute mesenteric ischemia is known as a life threatening condition. Re-establishment of blood flow in this condition can lead to mesenteric ischemia reperfusion (MIR) injury which is accompanied by inflammatory response. Still, clear blueprint of inflammatory mechanism underlying MIR injury has not been provided. Interestingly, Albendazole has exhibited notable effects on inflammation and cytokine production. In this study, we aimed to evaluate outcomes of MIR injury following pretreatment with Albendazole with respect to assessment of mesenteric inflammation and ischemia threshold. MethodsMale rats were randomly divided into sham operated, vehicle treated, Albendazole 100 mg/kg and Albendazole 200 mg/kg groups. MIR injury was induced by occlusion of superior mesenteric artery for 30 min followed by 120 min of reperfusion. Samples were utilized for assessment of epithelial survival and villous height. Immunohistochemistry study revealed intestinal expression of TNF-α and HIF-1-α. Gene expression of NF-κB/TLR4/TNF-α/IL-6 was measured using RTPCR. Also protein levels of inflammatory cytokines in serum and intestine were assessed by ELISA method. ResultsHistopathological study demonstrated that pretreatment with Albendazole could ameliorate decline in villous height and epithelial survival following MIR injury. Also, systemic inflammation was suppressed after administration of Albendazole. Analysis of possible participating inflammatory pathway could demonstrate that intestinal expression of NF-κB/TLR4/TNF-α/IL-6 is significantly attenuated in treated groups. Eventually, IHC study illustrated concordant decline in mesenteric expression of HIF-1-α/TNF-α. ConclusionSingle dose pretreatment with Albendazole could ameliorate inflammatory response and enhance ischemia threshold following induction of MIR injury. More studies would clarify existing causality in this phenomenon.

Colonization with Altered Schaedler Flora Impacts Leukocyte Adhesion in Mesenteric Ischemia-Reperfusion Injury.

The microbiota impacts mesenteric ischemia-reperfusion injury, aggravating the interaction of leukocytes with endothelial cells in mesenteric venules. The role of defined gut microbiomes in this life-threatening pathology is unknown. To investigate how a defined model microbiome affects the adhesion of leukocytes in mesenteric ischemia-reperfusion, we took advantage of gnotobiotic isolator technology and transferred altered Schaedler flora (ASF) from C3H/HeNTac to germ-free C57BL/6J mice. We were able to detect all eight bacterial taxa of ASF in fecal samples of colonized C57BL/6J mice by PCR. Applying qRT-PCR for quantification of species-specific 16S rDNA sequences of ASF bacteria, we found a major shift in the abundance of ASF 500, which was greater in C57BL/6J mice relative to the C3H/HeNTac founder breeding pair. Using high-speed epifluorescence intravital microscopy to visualize the venules of the small bowel mesentery, we found that gnotobiotic ASF-colonized mice showed reduced leukocyte adherence, both pre- and post-ischemia. Relative to germ-free mice, the counts of adhering leukocytes were increased pre-ischemia but did not significantly increase in ASF-colonized mice in the post-ischemic state. Collectively, our results suggest a protective role of the minimal microbial consortium ASF in mesenteric ischemia-reperfusion injury.

Evaluation of protective effect of L-carnitine and N-acetylcysteine in mesenteric ischemia-reperfusion injury model in rats

Evaluation of protective effect of L-carnitine and N-acetylcysteine in mesenteric ischemia-reperfusion injury model in rats

Eicosanoid production varies by sex in mesenteric ischemia reperfusion injury

Intestinal ischemia/reperfusion (I/R)-induced injury is an inflammatory response with significant morbidity and mortality. The early inflammatory response includes neutrophil infiltration. However, the majority of rodent studies utilize male mice despite a sexual dimorphism in intestinal I/R-related diseases. We hypothesized that sex may alter inflammation by changing neutrophil infiltration and eicosanoid production. To test this hypothesis, male and female C57Bl/6 mice were subjected to sham treatment or 30 min intestinal ischemia followed by a time course of reperfusion. We demonstrate that compared to male mice, females sustain significantly less intestinal I/R-induced tissue damage and produced significant LTB4 concentrations. Male mice release PGE2. Finally, treatment with a COX-2 specific inhibitor, NS-398, attenuated I/R-induced injury, total peroxidase level, and PGE2 production in males, but not in similarly treated female mice. Thus, I/R-induced eicosanoid production and neutrophil infiltration varies between sexes suggesting that distinct therapeutic intervention may be needed in clinical ischemic diseases.

Gut Microbiota Restricts NETosis in Acute Mesenteric Ischemia-Reperfusion Injury.

Recruitment of neutrophils and formation of neutrophil extracellular traps (NETs) contribute to lethality in acute mesenteric infarction. To study the impact of the gut microbiota in acute mesenteric infarction, we used gnotobiotic mouse models to investigate whether gut commensals prime the reactivity of neutrophils towards formation of neutrophil extracellular traps (NETosis). Approach and Results: We applied a mesenteric ischemia-reperfusion (I/R) injury model to germ-free (GF) and colonized C57BL/6J mice. By intravital imaging, we quantified leukocyte adherence and NET formation in I/R-injured mesenteric venules. Colonization with gut microbiota or monocolonization with Escherichia coli augmented the adhesion of leukocytes, which was dependent on the TLR4 (Toll-like receptor-4)/TRIF (TIR-domain-containing adapter-inducing interferon-β) pathway. Although neutrophil accumulation was decreased in I/R-injured venules of GF mice, NETosis following I/R injury was significantly enhanced compared with conventionally raised mice or mice colonized with the minimal microbial consortium altered Schaedler flora. Also ex vivo, neutrophils from GF and antibiotic-treated mice showed increased LPS (lipopolysaccharide)-induced NETosis. Enhanced TLR4 signaling in GF neutrophils was due to elevated TLR4 expression and augmented IRF3 (interferon regulatory factor-3) phosphorylation. Likewise, neutrophils from antibiotic-treated conventionally raised mice had increased NET formation before and after ischemia. Increased NETosis in I/R injury was abolished in conventionally raised mice deficient in the TLR adaptor TRIF. In support of the desensitizing influence of enteric LPS, treatment of GF mice with LPS via drinking water diminished LPS-induced NETosis in vitro and in the mesenteric I/R injury model. Collectively, our results identified that the gut microbiota suppresses NETing neutrophil hyperreactivity in mesenteric I/R injury, while ensuring immunovigilance by enhancing neutrophil recruitment.

Protection by the Eph-Ephrin System Against Mesenteric Ischemia-Reperfusion Injury.

Mesenteric ischemia-reperfusion (I/R)-induced injury targets primarily endothelial and epithelial cells, leading to a cascade of inflammatory events, eventually culminating in life-threatening syndromes. Hitherto, the role of Eph, the largest family of tyrosine kinase receptors, and of their cell-bound ephrin ligands, whose interaction generates a bidirectional signaling, is still debated in I/R injury. The aim of the present work was therefore to investigate the effects produced by unidirectional activation of forward signaling (administration of chimeric protein ephrinA1-Fc), of reverse signaling (EphA2-Fc), or inhibition of both signals (monomeric EphA2 and the protein-protein interaction inhibitor UniPR1331) on the local and systemic inflammatory responses triggered by mesenteric I/R in mice.When administered at 200 μg/kg i.v., ephrin-A1-Fc prevented intestinal and lung I/R-induced injury, decreasing in the pulmonary district leukocytes recruitment, IL-1β and TNFα levels, and EphA2 overexpression by mesenteric I/R. Blockade of Eph-ephrin signaling by equimolar EphA2 efficiently antagonized I/R-induced gut edema formation, an effect shared also by UniPR1331, mitigated lung mucosal injury, and counteracted the increase in pro-inflammatory cytokines levels. EphA2-Fc 180 μg/kg or equimolar Fc alone did not significantly modify the inflammatory responses to I/R.Our data suggest that the Eph-ephrin system is directly involved in the development of the acute inflammatory process activated in the gut by hypoxia-reoxygenation and in its amplification to distant organs, revealing that a fine pharmacological tuning of this signaling pathway may represent an attractive strategy to contain the I/R-induced inflammatory cascade.

Postconditioning: “Toll-erating” mesenteric ischemia-reperfusion injury?

Postconditioning may prove to be a suitable method to decrease ischemia-reperfusion injury of intestine after mesenteric arterial occlusion. Toll-like-receptor-4 is involved in the pathophysiology of organ damage after ischemia-reperfusion; therefore, the aim of our study was to investigate the effect of postconditioning on the mucosal expression of toll-like-receptor-4. Male Wistar rats (n=10/group) underwent 60minutes of superior mesenteric artery occlusion followed by 6hours of reperfusion in 3 groups: sham-operated, ischemia-reperfusion, and a postconditioned group. Postconditioning was performed by 6 alternating cycles of 10seconds of reperfusion/reocclusion. Blood and tissue samples were collected at the end of reperfusion. Intestinal histopathologic changes and immunohistochemical expression of mucosal caspase-3, antioxidant status, and protein levels of high-mobility group box-1 and toll-like-receptor-4 were assessed. Immunofluorescent labeling and confocal microscopic analysis of toll-like-receptor-4 were performed. Mucosal and serum levels of interleukin-6 and tumor necrosis factor-α protein were measured. Histologic alterations in the postconditioned group were associated with decreased caspase-3 positivity, less toll-like-receptor-4 mRNA, and less protein expression of high-mobility group box-1 and toll-like-receptor-4 in the intestinal villi compared with the ischemia-reperfusion group. Furthermore, a significantly improved antioxidant state of the intestinal mucosa and less mucosal and serum protein levels of interleukin-6 and tumor necrosis factor-α were detected in the postconditioned group. Small intestinal ischemia-reperfusion injury in male Wistar rats caused by the occlusion of the superior mesenteric artery was ameliorated by the use of postconditioning, showing a more favorable inflammatory response, which may be attributed to the decreased mucosal expression of toll-like-receptor-4.

Evaluation of matrix metalloproteinase, myeloperoxidase, and oxidative damage in mesenteric ischemia-reperfusion injury.

In this study, we investigated the alterations of matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinases (TIMPs), acute inflammation, and oxidative damage in the circulatory system and the intestine in response to mesenteric ischemia/reperfusion (I/R). Twenty-one rats were divided randomly into the following three groups (n = 7 in each group): a sham group (CG), an ischemic group (IG), and an I/R group (I/RG). MMP-9, TIMP-1, and myeloperoxidase (MPO) were measured using the enzyme-linked immunosorbent assay method, and lipid peroxidation (quantified as thiobarbituric acid reactive substances (TBARS) content), ischemia-modified albumin, the prooxidant-antioxidant balance (PAB), and ferric-reducing antioxidant power (FRAP) were measured spectrophotometrically. The degree of intestinal injury was evaluated according to the Chiu scoring system. A significant difference between the mean serum TIMP-1 and MMP-9 levels and the alanine transaminase activity was found among the groups. Compared with the I/RG group a significant difference in the mean tissue MMP-9, MPO, and TBARS levels in addition to the PAB and FRAP was found between the CG and IG groups. The level of MMP-9 also demonstrated a strong, positive, and valid correlation with the TBA-RS levels. A significant morphological change was observed in both the IG and the I/RG groups. The degree of intestinal injury was more severe in the I/R group and was characterized by either villous denudation or villous loss. These results suggest that MMP-9, TIMP-1, MPO, and oxidative stress may be important in the intestinal injury development that is induced by acute mesenteric I/R in a rat model. MMP-9 overexpression may increase the extent of intestinal villous loss, particularly when MMP-9 is upregulated by the TBARS present in the intestinal injury.

The antioxidant effects of pomegranate extract on local and remote organs in a mesenteric ischemia and reperfusion model

Objectives: We investigated whether pomegranate extract plays a protective antioxidant role against mesenteric ischemia–reperfusion injury (IR), which can lead to a systemic response and damage distant organs, such as the lung, liver, and kidney.Methods: Forty female Wistar–Albino rats were separated into four groups: laparotomy, laparotomy + PG, mesenteric IR, and mesenteric IR and pomegranate (IR + PG). In the laparotomy + PG and IR + PG groups, pomegranate (225 mg/kg) was given by oral gavage at the beginning of the study. Ischemia was induced for 30 minutes, and reperfusion was subsequently allowed for 60 minutes in the IR and IR + PG groups. The malondialdehyde (MDA) and total antioxidant activity (AOA) levels were evaluated in blood samples. Additionally, all tissues were removed for the measurement of AOA and total oxidant status as well as for subsequent histopathological evaluation. The oxidative stress index was calculated.Results: Histopathological changes in all organs were significantly higher in the IR group and significantly lower in the IR + PG group vs. the other groups. Serum MDA levels were significantly lower in the IR + PG group than in the IR group. No significant difference was found in AOA levels of the groups.Discussion: These data may explain the positive protective effects of pomegranate based on the histopathologic findings in ischemic conditions in an intestinal IR injury model.

Induced pluripotent stem cells alleviate lung injury from mesenteric ischemia-reperfusion.

Mesenteric ischemia-reperfusion (I/R) injury is a serious pathophysiologic process that can trigger the development of multiorgan dysfunction. Acute lung injury is a major cause of death among mesenteric I/R patients, as current treatments remain inadequate. Stem cell-based therapies are considered novel strategies for treating several devastating and incurable diseases. This study examined whether induced pluripotent stem cells (iPSCs) lacking c-myc (i.e., induced using only the three genes oct4, sox2, and klf4) can protect against acute lung injury in a mesenteric I/R mouse model. C57BL/6 mice were randomly divided into the following groups: sham/no treatment, vehicle treatment with phosphate-buffered saline, treatment with iPSCs, and treatment with iPSC-conditioned medium. The mice were subjected to mesenteric ischemia for 45 minutes followed by reperfusion for 24 hours. After I/R, the lungs and the ileum of the mice were harvested. Lung injury was evaluated by histology, immunohistochemistry, and analyses of the levels of inflammatory cytokines, cleaved caspase 3, and 4-hydroxynonenal. The intravenously delivered iPSCs engrafted to the lungs and the ileum in response to mesenteric I/R injury. Compared with the phosphate-buffered saline-treated group, the iPSC-treated group displayed a decreased intensity of acute lung injury 24 hours after mesenteric I/R. iPSC transplantation significantly reduced the expression of proinflammatory cytokines, oxidative stress markers, and apoptotic factors in injured lung tissue and remarkably enhanced endogenous alveolar cell proliferation. iPSC-conditioned medium treatment exerted a partial effect compared with iPSC treatment. When considering the anti-inflammatory, antioxidant, and antiapoptotic properties of iPSCs, the transplantation of iPSCs may represent an effective treatment option for mesenteric I/R-induced acute lung injury.

Protective effects of dexmedetomidine on intestinal ischemia-reperfusion injury.

Dexmedetomidine (DEX) has been hypothesized to possess anti-oxidative properties that may mitigate the damage caused by ischemia-reperfusion (IR) injury. The aim of the present study was to examine the effects of DEX on intestinal contractile activity, inflammation and apoptosis following intestinal IR injury. Intestinal IR injury was induced in rats by complete occlusion of the superior mesenteric artery for 60 min, followed by a 60-min reperfusion period. Rats received an intraperitoneal injection of 25 µg/kg DEX at 30 min prior to the mesenteric IR injury. Following reperfusion, segments of the terminal ileum were rapidly extracted and transferred into an isolated organ bath. The contractile responses to receptor-mediated acetylcholine (Ach) and non-receptor-mediated potassium chloride (KCl) were subsequently examined. Nitric oxide (NO) levels were determined and the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, Bax and Bcl-2 were measured using an enzyme-linked immunosorbent assay. The levels of telomerase and caspase-3 were determined using reverse transcription-quantitative polymerase chain reaction. The results indicated that DEX treatment produced a significant reduction in the IR-induced contractile response to Ach and KCl in the intestinal tissue. Furthermore, DEX appeared to significantly ameliorate intestinal IR injury, in addition to reducing the production of NO. Similar reductions were observed in the intestinal expression levels of TNF-α and IL-6. In addition, DEX treatment resulted in a reduction in the expression levels of Bax in the intestinal tissues, while increasing those of Bcl-2, in addition to significantly increasing the mRNA levels of telomerase and caspase-3. Therefore, the present study indicated that NO, TNF-α and IL-6 may partially contribute to the pathogenesis of intestinal IR injury in addition to the increased expression levels of Bax, Bcl-2, telomerase and caspase-3. These findings suggest that DEX possesses beneficial anti-apoptotic and anti-inflammatory effects in intestinal tissue following bowel injury.

The Effect of Silymarin on Mesenteric Ischemia-Reperfusion Injury

Objective: To examine the effect of silymarin (SM), a mixture of flavonoids and polyphenols extracted from Silybum marianum, on mesenteric ischemia-reperfusion (I-R) injury in a rat model. Materials and Methods: Fifty rats were randomly divided into 5 groups (n = 10). Group 1 was sham operated, while groups 2-5 were subjected to mesenteric I-R lasting 1 h. Group 2 received isotonic sodium chloride, group 3 received SM (100 mg/kg/day) for 7 days before I-R, group 4 received SM for 7 days after I-R, and group 5 received SM for 7 days both before and after I-R. The rats were sacrificed by exsanguination in groups 1-3 at the 24th hour and groups 4 and 5 were sacrificed on the 7th day of reperfusion. Blood and intestinal specimens were taken for biochemical and pathological evaluations. Results: Serum superoxide dismutase (SOD) and heat shock protein 70 levels were significantly higher in group 2 (5.24 ± 1.76 U/l and 261.4 ± 16.8 ng/ml) compared to the sham group (2.08 ± 1.76 U/l and 189.9 ± 28.7 ng/ml) (p < 0.001 and p < 0.0001, respectively). However, SOD activity and the extent and severity of the histopathological lesions were significantly less in groups 3 [3.11 ± 1.18 U/l, 1.0 (range 0.0-2.0)], 4 [2.15 ± 0.87 U/l, 1.0 (range 1.0-3.0)], and 5 [1.80 ± 0.61 U/l, 0.5 (range 0.0-2.0)], treated with SM, than in group 2 [5.24 ± 1.76 U/l, 2.0 (range 2.0-3.0)] (p = 0.002, p < 0.001, and p = 0.0001; p < 0.001, p = 0.007, and p = 0.0001, respectively). Also, TNF-α levels were lower in the SM-supplemented groups compared to group 2. Serum thiobarbituric acid-reactive substance concentrations were low in the pre-/posttreatment groups treated with SM compared to group 2. No statistical difference was observed for protein carbonyls between the groups. Conclusion: Our findings suggest that SM therapy may attenuate the oxidative and intestinal damage induced by I-R injuries.

Mesenteric ischemia-reperfusion injury up-regulates certain CC, CXC, and XC chemokines and results in multi-organ injury in a time-dependent manner

Trauma patients who develop multi-organ dysfunction have increased systemic levels of chemotactic cytokines. Ischemia-reperfusion (IR) injury to the gut may play a role. The purpose of this study was to examine chemokine production in a mouse model of mesenteric IR injury. Given the pre-eminent role of the neutrophil, there has been much investigation of the CXC chemokines, but very limited research on the CC and XC chemokines. We hypothesized that intestinal IR injury would induce remote organ injury and enhance serum CC and XC chemokine levels. Fasted female C57BL6 mice were anesthetized prior to laparotomy. In IR animals, the superior mesenteric artery (SMA) was occluded for 30, 45, or 75 min, while controls underwent sham laparotomy, n = 5-7 per group. After the indicated time point, the incision was closed and the mouse was allowed to recover for six hours. Following euthanasia, serum levels of 15 chemokines (10 CC, 4 CXC, and 1 XC) were assessed and histopathologic analyses performed. Seventy-five minutes of SMA occlusion was the key time frame for significant serum cytokine level up-regulation, intestinal and remote organ injury, and neutrophil influx into tissues. With 75 min of intestinal ischemia, significantly elevated serum levels, as compared to shams, were noted for seven CC chemokines: MCP-1, MCP-3, MIP-1β, MIP-3β, eotaxin, MDC, and RANTES. Levels of the XC chemokine lymphotactin also increased. Levels of MIP-2, IP-10, and KC/GRO (CXC chemokines) rose significantly. MIP-1α levels were only significantly increased at 45 min IR. We did not find any significant IR injury-induced changes in levels of MCP-5, MIP-1γ, or GCP-2, at any ischemia time frame. Serum levels of IL-6 correspondingly increased significantly with longer ischemia times. The novel finding of this study is the demonstration of significant systemic increases in the CC chemokines eotaxin, MCP-3, MDC, MIP-3β in a time-dependent manner, along with tissue injury. The data suggest a complex response to IR injury whereby chemokines that are active on a variety of leukocytes may play a role in inducing local and remote tissue injury.

Mesenteric Ischemia-Reperfusion (IR) Injury Enhances Mouse Chemokine Production and Results in Injury to Multiple Organs

Mesenteric Ischemia-Reperfusion (IR) Injury Enhances Mouse Chemokine Production and Results in Injury to Multiple Organs

Complement depletion protects lupus-prone mice from ischemia-reperfusion-initiated organ injury

Ischemia-reperfusion (IR) injury causes a vigorous immune response that is amplified by complement activation, leading to local and remote tissue damage. Using MRL/lpr mice, which are known to experience accelerated tissue damage after mesenteric IR injury, we sought to evaluate whether complement inhibition mitigates organ damage. We found that complement depletion with cobra venom factor protected mice from local and remote lung tissue damage. Protection from injury was associated with less complement (C3) and membrane attack complex deposition, less neutrophil infiltration, and lower levels of local proinflammatory cytokine production. In addition, complement depletion was able to decrease the level of oxidative stress as measured by glutathione peroxidase 1 mRNA levels and superoxide dismutase activity. Furthermore, blockage of C5a receptor protected MRL/lpr mice from local tissue damage, but not from remote lung tissue damage. In conclusion, although treatments with cobra venom factor and C5a receptor antagonist were able to protect mice from local tissue damage, treatment with C5a receptor antagonist was not able to protect mice from remote lung tissue damage, implying that more factors contribute to the development of remote tissue damage after IR injury. These data also suggest that complement inhibition at earlier, rather than late, stages can have clinical benefit in conditions that are complicated with IR injury.

Complement Orchestrates T cell response during Mesenteric Ischemia Reperfusion Injury in Autoimmune Prone Mice. (171.22)

Abstract Ischemia reperfusion injury is a type of injury seen in clinical conditions, such as trauma, hemorrhagic shock, organ transplantation, revascularization processes, and autoimmune diseases like systemic lupus erythematosus. MRL/lpr mice due to their autoimmune background present with accelerated mesenteric ischemia reperfusion injury (IR/I). To evaluate the effect of complement inhibition on tissue damage after mesenteric IR in MRL/lpr mice, we depleted complement using Cobra Venom factor (CVF) or blocked C5a receptor with a C5aR antagonist, and performed intestinal ischemia reperfusion. First, we confirmed that CVF treatment completely depleted C3 from the mice serum. Next, we found that the treatment with either CVF or C5aR antagonist attenuated intestinal injury following intestinal IR. Notably, depletion of complement increased the presence of IL-10 producing CD4+ cells (Tr1) and IL-10 producing Th17 cells in the intestine. These results suggest that complement may regulate the T-cell response during intestinal ischemia reperfusion injury.

Inhibition of Syk activity by R788 in platelets prevents remote lung tissue damage after mesenteric ischemia-reperfusion injury

Tissue injury following ischemia-reperfusion (I/R) occurs as a consequence of actions of soluble factors and immune cells. Growing evidence supports a role for platelets in the manifestation of tissue damage following I/R. Spleen tyrosine kinase has been well documented to be important in lymphocyte activation and more recently in platelet activation. We performed experiments to evaluate whether inhibition of platelet activation through inhibition of spleen tyrosine kinase prevents tissue damage after mesenteric I/R injury. Platelets isolated from C57BL/6J mice fed with R788 for 10 days were transfused into C57BL/6J mice depleted of platelets 2 days before mesenteric I/R injury. Platelet-depleted mice transfused with platelets from R788-treated mice before mesenteric I/R displayed a significant reduction in the degree of remote lung damage, but with little change in the degree of local intestinal damage compared with control I/R mice. Transfusion of R788-treated platelets also decreased platelet sequestration, C3 deposition, and immunoglobulin deposition in lung, but not in the intestine, compared with control groups. These findings demonstrate that platelet activation is a requisite for sequestration in the pulmonary vasculature to mediate remote tissue injury after mesenteric I/R. The use of small-molecule inhibitors may be valuable to prevent tissue damage in remote organs following I/R injury.

Mesenteric ischemia-reperfusion injury: Clearly improved hemodynamics but only minor protection of the rat small intestine by (sub)therapeutic heparin sodium and enoxaparin doses

BackgroundTissue protection against ischemia (I)/reperfusion (R) injury by heparins can be due to their anticoagulant and/or non-anticoagulant properties. Here we studied the protective potential of the anticoagulant and the non-anticoagulant features of heparin sodium (HepSo) and enoxaparin (Enox) against mesenteric I/R injury in a rat model. Materials and methodsMesenteric I/R was induced in rats (n = 6 per group) by superior mesenteric artery occlusion (SMAO; 90 min) and reopening (120 min). Therapeutic/clinical and subtherapeutic/non-anticoagulant doses of HepSo (0.25 mg/kg bolus + 0.25 mg/kg × h; 0.05 mg/kg bolus + 0.1 mg/kg × h) or Enox (0.5 mg/kg bolus + 0.5 mg/kg × h; 0.05 mg/kg bolus + 0.1 mg/kg × h) were administered intravenously starting 30 min before SMAO to the end of reperfusion. Systemic/vital and intestinal microcirculatory parameters were measured during the whole experimental procedure, those of small intestine injury at the end. ResultsDuring intestinal reperfusion, mean arterial blood pressure and heart rates were significantly increased by HepSo and, less effectively, by Enox, in a dose-dependent manner. Intestinal microcirculation was only affected by the therapeutic HepSo dose, which decreased the microvascular flow and SO2 during reperfusion. The subtherapeutic Enox treatment, as opposed to any HepSo dose, most effectively diminished I/R-induced intestinal hemorrhages, myeloperoxidase activity (as a measure of neutrophil invasion), and histopathological changes. ConclusionTherapeutic but, to a lesser extent, also the subtherapeutic doses of both HepSo and Enox clearly improve hemodynamics during mesenteric reperfusion, while intestinal protection is exclusively provided by Enox, especially at its subtherapeutic dose. Alterations in intestinal microcirculation are not responsible for these effects. Thus, non-anticoagulant Enox doses and, preferably, heparin(oid)s unable to affect coagulation, could diminish clinical risks of I/R-induced gastrointestinal complications.

The study of renal ischemia remote postconditioning intervention in the rabbits acute mesenteric ischemia-reperfusion injury model

Objective To study the effect of ischemia remote postconditioning (renal) intervention in the rabbits acute mesenteric ischemia-reperfusion injury model.Methods 90 rabbits were divided randomly into Con,I/R,IRpostC group (n =30).I/R models were established by clamping-releasing the superior mesenteric artery.To detect the levels of malondialdehyde (MDA) and myeloperoxidase (MPO) in intestinal tissues by kit.To determin the pathology score of damaged intestinal mucosae by chiu-6 standared.The damage of intestinal epithelial cells were observed by electron microscopy.Results The MDA,MPO levels and pathology score in intestinal tissues was ( 14.72 ± 0.21 ) nmol/mg,( 1.65 ± 0.35 ) U/g,3.30 ± 0.69 respectively in I/R group,and in IRpost C group was (7.13 ±0.40) nmol/mg,(0.91 ±0.33) U/g,2.10 ±0.92 respectively.There were increased obviously compared with the Con group [ (3.28 ±0.26) nmol/mg,(0.52 ±0.23) U/g,0.69 ±0.52].Compared with the I/R group,the MDA,MPO levels and pathology score in intestinal tissues were decreased obviously in the IRpostC group (P ＜ O.01 ).Cells damage were reduced significantly in IRpostC group compared with the I/R group by electron microscope.Conclusion The acute mesenteric ischemia-reperfusion injury were reduced by ischemia remote postconditioning (renal) intervention in rabbits. Key words: Ischemia; Reperfusion injury; Ischemia remote postconditioning; Animals; Intestines