Inhibition of Rho kinase by fasudil hydrochloride attenuates lung injury induced by intestinal ischemia and reperfusion

AimThe aim of this study is to evaluate the role of Rho-kinase in the pathogenesis of lung injury induced by intestinal ischemia/reperfusion (I/R) and the preconditioning effects of fasudil hydrochloride. The novel therapeutic approach of using Rho-kinase inhibitors in the treatment of intestinal I/R is introduced.MethodsSprague–Dawley (SD) rats were divided into 4 groups: intestinal I/R group, two fasudil pretreatment groups (7.5 mg/kg and 15 mg/kg), and controls. Intestinal and lung histopathology was evaluated; myeloperoxidase (MPO) and superoxide dismutase (SOD) levels in lung parenchyma were determined. Serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured. eNOS and P-ERM expression were measured by Western Blot.ResultsLung and intestinal injury were induced by intestinal I/R, characterized by histological damage and a significant increase in BALF protein. Compared to controls, serum TNF-α, IL-6, and lung MPO activity increased significantly in the I/R group, while SOD activity decreased. A strongly positive P-ERM expression was observed, while eNOS expression was weak. After fasudil administration, injury was ameliorated. Serum TNF-α, IL-6, lung MPO and P-ERM expression decreased significantly as compared to the I/R group, while SOD activity and eNOS expression increased significantly.SignificanceRho-kinase plays a key role in the pathogenesis of lung injury induced by intestinal I/R. The inhibition of the Rho-kinase pathway by fasudil hydrochloride may prevent lung injury.     

Transient ureteral obstruction prevents against kidney ischemia/reperfusion injury via hypoxia-inducible factor (HIF)-2α activation

Although the protective effect of transient ureteral obstruction (UO) prior to ischemia on subsequent renal ischemia/reperfusion (I/R) injury has been documented, the underlying molecular mechanism remains to be understood. We showed in the current study that 24 h of UO led to renal tubular hypoxia in the ipsilateral kidney in mice, with the accumulation of hypoxia-inducible factor (HIF)-2α, which lasted for a week after the release of UO. To address the functions of HIF-2α in UO-mediated protection of renal IRI, we utilized the Mx-Cre/loxP recombination system to knock out target genes. Inactivation of HIF-2α, but not HIF-1α blunted the renal protective effects of UO, as demonstrated by much higher serum creatinine level and severer histological damage. UO failed to prevent postischemic neutrophil infiltration and apoptosis induction in HIF-2α knockout mice, which also diminished the postobstructive up-regulation of the protective molecule, heat shock protein (HSP)-27. The renal protective effects of UO were associated with the improvement of the postischemic recovery of intra-renal microvascular blood flow, which was also dependent on the activation of HIF-2α. Our results demonstrated that UO protected the kidney via activation of HIF-2α, which reduced tubular damages via preservation of adequate renal microvascular perfusion after ischemia. Thus, preconditional HIF-2α activation might serve as a novel therapeutic strategy for the treatment of ischemic acute renal failure.     

High mobility box 1 mediates neutrophil recruitment in myocardial ischemia-reperfusion injury through toll like receptor 4-related pathway

This study aimed to explore the role of high mobility box 1 (HMGB1) and its receptor toll like receptor 4 (TLR4) on neutrophils in myocardial ischemia reperfusion (I/R) injury. We constructed TLR4-mutant (C3H/HeJ) and control (C3H/HeN) mouse models of myocardial I/R injury and subjected the mice to 30min of ischemia and 6h of reperfusion. Light microscope was used to observe structural changes in the myocardium. HMGB1 levels were measured using quantitative real-time PCR and immunohistochemistry. Neutrophil accumulation, TNF-a expression and IL-8 levels were analyzed via myeloperoxidase (MPO) biochemical studies, quantitative real-time PCR and ELISA, respectively. The results demonstrated that fewer neutrophils infiltrated in the myocardium of TLR4-mutant mice after myocardial I/R and that TLR4 deficiency markedly decreased the ischemic injury caused by ischemia/reperfusion, and inhibited the expression of HMGB1, TNF-a, and IL-8, all of which were up-regulated by ischemia/reperfusion. These findings suggest that HMGB1 plays a central role in recruiting neutrophils during myocardial I/R leading to worsened myocardial I/R injury. This recruitment mechanism is possibly due to its inflammatory and chemokine functions based on the TLR4-dependent pathway.     

Potentiation of endogenous fibrinolysis and rescue from lung ischemia/reperfusion injury in interleukin (IL)-10-reconstituted IL-10 null mice

Little is known about interactions between endogenous anti-inflammatory paradigms and microvascular thrombosis in lung ischemia/reperfusion (I/R) injury. Interleukin (IL)-10 suppresses macrophage activation and down-regulates proinflammatory cytokine production, but there are no available data to suggest a link between IL-10, thrombosis, and fibrinolysis in the setting of I/R. We hypothesized that hypoxia/ischemia triggers IL-10 production, to dampen proinflammatory cytokine and adhesion receptor cascades and to restore vascular patency by fibrinolytic potentiation. Studies were performed in a mouse lung I/R model. IL-10 mRNA levels in lung were increased 43-fold over base line by 1 h of ischemia/2 h of reperfusion, with a corresponding increase in plasma IL-10. Expression was prominently localized in bronchial epithelial cells and mononuclear phagocytes. To study the link between IL-10 and fibrinolysis in vivo, the induction of plasminogen activator inhibitor-1 (PAI-1) was evaluated. Northern analysis demonstrated exaggerated pulmonary PAI-1 expression in IL-10 (-/-) mice after I/R, with a corresponding increase in plasma PAI/tissue-type plasminogen activator activity. In vivo, IL-10 (-/-) mice showed poor postischemic lung function and survival after I/R compared with IL-10 (+/+) mice. Despite a decrease in infiltration of mononuclear phagocytes in I/R lungs of IL-10 (-/-) mice, an increased intravascular pulmonary fibrin deposition was observed by immunohistochemistry and Western blotting, along with increased IL-1 expression. Recombinant IL-10 given to IL-10 (-/-) mice normalized the PAI/tissue-type plasminogen activator ratio, reduced pulmonary vascular fibrin deposition, and rescued mice from lung injury. Since recombinant hirudin (direct thrombin inhibitor) also sufficed to rescue IL-10 (-/-) mice, these data suggest a preeminent role for microvascular thrombosis in I/R lung injury. Ischemia-driven IL-10 expression confers postischemic pulmonary protection by augmenting endogenous fibrinolytic mechanisms.     

Activation of the MyD88 signaling pathway inhibits ischemia-reperfusion injury in the small intestine

Toll-like receptors (TLRs) recognize microbial components and trigger the signaling cascade that activates innate and adaptive immunity. Recent studies have shown that the activation of TLR-dependent signaling pathways plays important roles in the pathogenesis of ischemia-reperfusion (I/R) injuries in many organs. All TLRs, except TLR3, use a common adaptor protein, MyD88, to transduce activation signals. We investigated the role of MyD88 in I/R injury of the small intestine. MyD88 and cyclooxygenase-2 (COX-2) knockout and wild-type mice were subjected to intestinal I/R injury. I/R-induced small intestinal injury was characterized by infiltration of inflammatory cells, disruption of the mucosal epithelium, destruction of villi, and increases in myeloperoxidase activity and mRNA levels of TNF-α and the IL-8 homolog KC. MyD88 deficiency worsened the severity of I/R injury, as assessed using the histological grading system, measuring luminal contents of hemoglobin (a marker of intestinal bleeding), and counting apoptotic epithelial cells, while it inhibited the increase in mRNA expression of TNF-α and KC. I/R significantly enhanced COX-2 expression and increased PGE(2) concentration in the small intestine of wild-type mice, which were markedly inhibited by MyD88 deficiency. COX-2 knockout mice were also highly susceptible to intestinal I/R injury. Exogenous PGE(2) reduced the severity of injury in both MyD88 and COX-2 knockout mice to the level of wild-type mice. These findings suggest that the MyD88 signaling pathway may inhibit I/R injury in the small intestine by inducing COX-2 expression.     

Protective effects of salusin-α and salusin-β on renal ischemia/reperfusion damage and their levels in ischemic acute renal failure

Salusin-α and salusin-β are expressed in many tissues including the central nervous system, vessels and kidneys; they have been shown to decrease endoplasmic reticulum stress during heart ischemia/reperfusion (I/R) and to decrease apoptosis. We investigated the relation of salusin-α and salusin-β levels to acute ischemic renal failure. We also investigated whether these peptides are protective against renal I/R damage. Fifty-three rats were divided into six groups: control, I/R, I/R + salusin-α1, I/R + salusin-α10, I/R + salusin-β1 and I/R + salusin-β10. After removing the right kidney, the left kidney was subjected to ischemia for 1 h and reperfusion for 23 h. The treatment groups were injected subcutaneously at the beginning of ischemia with 1 or 10 μg/kg salusin-α, and 1 or 10 μg/kg salusin-β. Histopathology was assessed at the end of the experiment. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX) activity and malondialdehyde (MDA) levels were measured in the kidney tissue. Serum levels of blood urea nitrogen (BUN), creatinine (Cre), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-1 beta (IL-1β) also were measured. Levels of salusin-α and salusin-β were measured in the serum and kidney tissues of the control and I/R groups. SOD, CAT and GSH-PX activities were decreased and the levels of MDA, TNF-α, IL-6, IL-1β, BUN and Cre were increased in the I/R group compared to controls. Severe glomerular and tubular damage was apparent in the I/R group compared to controls. The level of salusin-β was decreased in the serum and kidney tissue of the I/R group compared to controls, whereas the level of salusin-α was decreased in the serum and increased in the kidney tissue. Salusin-α and salusin-β administration increased SOD and GSH-PX enzyme activation and decreased the levels of MDA, TNF-α, IL-6 and IL-1β compared to the I/R group. BUN and Cre levels were decreased in the I/R + salusin-α1 group and the level of Cre was decreased in I/R + salusin-β10 group compared to the I/R group. We demonstrated a protective effect of salusin-α and salusin-β against renal I/R damage. Changes in the levels of salusin-α and salusin-β in the I/R group suggest that these peptides may be associated with acute renal failure.     

缺血后处理降低高胆固醇血症大鼠心肌对缺血/再灌注损伤的易感性及其机制

目的:探讨缺血后处理对高胆固醇血症基础上发生的心肌缺血/再灌注损伤的影响及其可能的机制。方法:建立食源性高胆固醇血症大鼠模型,运用TTC染色、酶活性检测等方法测定缺血/再灌注所致的心肌损伤,用实时定量RT-PCR方法检测心肌组织中低氧诱导因子-1α(HIF-1α)mRNA水平,用Western blot方法检测HIF-1α蛋白水平。结果:高胆固醇血症加重了缺血/再灌注造成的心肌损伤,而缺血后处理显著缩小了高胆固醇血症大鼠缺血/再灌注所致的心梗面积,降低了血清肌酸激酶(CK)的活性,减少了心肌细胞凋亡。同时,缺血后处理提高了高胆固醇血症大鼠缺血心肌组织中HIF-1α的蛋白水平。结论:缺血后处理可以降低高胆固醇血症大鼠心肌对缺血/再灌注损伤的敏感性,其效应与心肌组织中HIF-1α的蛋白水平存在着相关性。     

TGF‐β1 improves mucosal IgA dysfunction and dysbiosis following intestinal ischaemia–reperfusion in mice

Intestinal ischaemia/reperfusion (I/R) severely disrupts gut barriers and leads to high mortality in the critical care setting. Transforming growth factor (TGF)‐β1 plays a pivotal role in intestinal cellular and immune regulation. However, the effects of TGF‐β1 on intestinal I/R injury remain unclear. Thus, we aimed to investigate the effects of TGF‐β1 on gut barriers after intestinal I/R and the molecular mechanisms. Intestinal I/R model was produced in mice by clamping the superior mesenteric artery for 1 hr followed by reperfusion. Recombinant TGF‐β1 was intravenously infused at 15 min. before ischaemia. The results showed that within 2 hrs after reperfusion, intestinal I/R disturbed intestinal immunoglobulin A class switch recombination (IgA CSR), the key process of mucosal IgA synthesis, and resulted in IgA dysfunction, as evidenced by decreased production and bacteria‐binding capacity of IgA. Meanwhile, the disruptions of intestinal microflora and mucosal structure were exhibited. Transforming growth factor‐β1 activated IgA CSR as evidenced by the increased activation molecules and IgA precursors. Strikingly, TGF‐β1 improved intestinal mucosal IgA dysfunction, dysbiosis and epithelial damage at the early stage after reperfusion. In addition, SB‐431542, a specific inhibitor of activating mothers against decapentaplegic homologue (SMAD) 2/3, totally blocked the inductive effect of TGF‐β1 on IgA CSR and almost abrogated the above protective effects on intestinal barriers. Taken together, our study demonstrates that TGF‐β1 protects intestinal mucosal IgA immunity, microbiota and epithelial integrity against I/R injury mainly through TGF‐β receptor 1/SMAD 2/3 pathway. Induction of IgA CSR may be involved in the protection conferred by TGF‐β1.     

肠缺血再灌注时肠内给予不同营养物对肠粘膜ATP含量的影响

将SD大鼠分组 ,先制作空肠袋 ,分别向袋内注射不同营养物 :10mmol/L丙氨酸 ,10mmol/L葡萄糖 ,10mmol/L甘露醇或 5mmol/L丙氨酸 +5mmol/L葡萄糖的混合液 ,用动脉夹阻断肠系膜上动脉血流 6 0min后 ,再恢复灌流 6 0min。分别于阻断血流 6 0min和恢复灌注 6 0min测定肠粘膜ATP含量。研究结果显示 ,缺血再灌注能显著降低肠粘膜ATP含量 ,给予丙氨酸或葡萄糖 /丙氨酸混合液使肠粘膜ATP含量进一步降低 (P <0 .0 1) ,而给予葡萄糖能显著增加肠粘膜ATP含量 (P <0 .0 1)。结论 :缺血再灌注过程中 ,肠内给予葡萄糖能改善肠粘膜ATP含量 ,对缺血再灌注损伤的肠道提供保护作用     

内毒素移位在肠淋巴再灌注加剧SMAO休克大鼠多器官损伤中的作用

目的:探讨肠源性内毒素移位在肠淋巴再灌注(MLR)加剧肠系膜上动脉闭塞性(SMAO)休克多器官损伤中的作用与机制。方法:24只Wistar大鼠随机分为4组(n=6):假手术组(Sham,仅麻醉与手术)、MLR组(夹闭肠系膜淋巴管1 h,再灌注2 h)、SMAO组(夹闭肠系膜上动脉1 h,再灌注2 h)和SMAO+MLR组(同时夹闭肠系膜淋巴管和肠系膜上动脉1 h,再灌注2 h)。再灌注2 h后,腹主动脉取血,制备血浆;留取固定位置的肝、肾、心肌、肺组织,制备组织匀浆。应用鲎试剂动态浊度法检测血浆以及各组织匀浆内毒素(ET)含量;应用酶联免疫方法检测各器官组织匀浆脂多糖结合蛋白(LBP)、脂多糖受体(CD14)和肿瘤坏死因子(TNF-α)水平。结果:Sham组和MLR组各指标均无统计学差异;SMAO组及SMAO+MLR组的血浆、肝、肾、心肌、肺组织匀浆的ET含量均显著高于Sham组和MLR组,且SMAO+MLR组血浆及各组织匀浆的ET水平均显著高于SMAO组;SMAO组及SMAO+MLR组肝、肾、心肌、肺组织匀浆CD14、LBP和TNF-α水平显著高于Sham组及MLR组,且SMAO+MLR组各指标均高于SMAO组。结论:MLR加剧SMAO休克多器官损伤的作用机制与ET经过肠淋巴途径移位、激活内毒素增敏系统LBP/CD14、促进炎症反应有关。     

Hibernation confers resistance to intestinal ischemia-reperfusion injury

The damaging effects of intestinal ischemia-reperfusion (I/R) on the gut and remote organs can be attenuated by subjecting the intestine to a prior, less severe I/R insult, a process known as preconditioning. Because intestines of hibernating ground squirrels experience repeated cycles of hypoperfusion and reperfusion, we examined whether hibernation serves as a model for natural preconditioning against I/R-induced injury. We induced intestinal I/R in either the entire gut or in isolated intestinal loops using rats, summer ground squirrels, and hibernating squirrels during natural interbout arousals (IBA; body temperature 37-39 degrees C). In both models, I/R induced less mucosal damage in IBA squirrels than in summer squirrels or rats. Superior mesenteric artery I/R increased MPO activity in the gut mucosa and lung of rats and summer squirrels and the liver of rats but had no effect in IBA squirrels. I/R in isolated loops increased luminal albumin levels, suggesting increased gut permeability in rats and summer squirrels but not IBA squirrels. The results suggest that the hibernation phenotype is associated with natural protection against intestinal I/R injury.     

AICAR Attenuates Organ Injury and Inflammatory Response after Intestinal Ischemia and Reperfusion

Intestinal ischemia and reperfusion (I/R) is encountered in various clinical conditions and contributes to multiorgan failure and mortality as high as 60% to 80%. Intestinal I/R not only injures the intestine, but affects remote organs such as the lung leading to acute lung injury. The development of novel and effective therapies for intestinal I/R are critical for the improvement of patient outcome. AICAR (5-aminoimidazole-4-carboxyamide ribonucleoside) is a cell-permeable compound that has been shown to possess antiinflammatory effects. The objective is to determine that treatment with AICAR attenuates intestinal I/R injury and subsequent acute lung injury (ALI). Male Sprague Dawley rats (275 to 325 g) underwent intestinal I/R injury with blockage of the superior mesenteric artery for 90 min and subsequent reperfusion. At the initiation of reperfusion, vehicle or AICAR (30 mg/kg BW) was given intravenously (IV) for 30 min. At 4 h after reperfusion, blood and tissues were collected for further analyses. Treatment with AICAR significantly decreased the gut damage score and the water content, indicating improvement in histological integrity. The treatment also attenuated tissue injury and proinflammatory cytokines, and reduced bacterial translocation to the gut. AICAR administration after intestinal I/R maintained lung integrity, attenuated neutrophil chemotaxis and infiltration to the lungs and decreased lung levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Inflammatory mediators, lung-inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins, were decreased in the lungs and lung apoptosis was significantly reduced after AICAR treatment. These data indicate that AICAR could be developed as an effective and novel therapeutic for intestinal I/R and subsequent ALI.     

Proteasome inhibition attenuates lung injury induced by intestinal ischemia reperfusion in rats

The aim of this study is to investigate the role of proteasome in the pathogenesis of lung injury induced by intestinal ischemia/reperfusion (I/R) by examining the effect of the proteasome inhibitor lactacystin on neutrophil infiltration, intracellular adhesion molecule-1 (ICAM-1) expression and nuclear factor kappa B (NF-κB) activation. Thirty-two Wistar rats were divided into (1) control, (2) intestinal I/R, (3) 0.2 mg/kg lactacystin pretreated, and (4) 0.6 mg/kg lactacystin pretreated groups (n = 8). Injuries in lung and intestine were induced by intestinal I/R, and were characterized by histological edema, hemorrhage and infiltration of inflammatory cells. The results showed a significant increase in serum creatine kinase B (CK-B) and lung water content in intestine and lung injuries. As compared with the control group, the myeloperoxidase (MPO) activity in intestine and lung as well as the serum TNF-α level increased significantly in intestinal I/R group. Simultaneously, expression of ICAM-1 and NF-κB p65 was also observed in the I/R group. Pre-treatment with lactacystin markedly reduced 20S proteasome activity in circulating white blood cells and ameliorated intestine and lung injuries. These results demonstrated that the proteasome participates in the pathogenesis of lung injury induced by intestinal I/R. Lactacystin as a proteasome inhibitor can prevent this kind of injury by decreasing ICAM-1 and TNF-α production via the inhibition of NF-κB activation.     

卡巴胆碱对缺血再灌注大鼠小肠组织髓过氧化物酶的影响

研究拟胆碱药卡巴胆碱对大鼠缺血再灌注损伤小肠组织髓过氧化物酶 (MPO)和丙二醛 (MDA)的影响及其与肠损伤相关指标变化的规律。Wistar大鼠被随机分为预防、治疗和对照三组。活杀后取小肠组织测MPO、MDA和肿瘤坏死因子 (TNF-α)含量。结果显示 ,治疗组及预防组MPO活性、MDA和TNF -α含量均明显低于对照组 ,治疗组与预防组之间差异不明显。提示卡巴胆碱可抑制致炎因子TNF -α的释放 ,减少中性粒细胞在肠组织的聚集 ,从而使小肠MPO活性降低     

mtDNA-STING pathway promotes necroptosis-dependent enterocyte injury in intestinal ischemia reperfusion

Intestinal ischemia reperfusion (I/R) injury is the important pathogenesis for acute intestinal barrier disruption. The STING signaling is associated with gut homeostasis and barrier integrity. However, the biological function and regulation of STING signaling in intestinal I/R injury are not yet fully understood. As the ligand of STING signaling, the mitochondrial DNA (mtDNA) has been found to be associated with necroptosis. It still remains unknown whether mtDNA-STING signaling triggers intestinal necroptosis in intestinal I/R injury. We found that circulating RIPK3 was significantly increased and had a positive correlation with markers of enterocyte injury in critically ill patients with intestinal injury. Moreover, the levels of circulating mtDNA were also associated with the levels of circulating RIPK3. To explore the relationship between mtDNA and intestinal necroptosis, mice were treated with the intraperitoneal injection of mtDNA, and necroptosis signaling was remarkably activated and the inhibition of necroptosis alleviated mtDNA-induced intestinal injury. Furthermore, STING knockout mice showed an alleviated intestinal necroptosis. In intestinal I/R injury, mtDNA was released from IECs and necroptosis was also triggered, companied with a significant decrease of RIPK3 in the intestine. STING knockout mice markedly attenuated intestinal necroptosis and intestinal I/R injury. Finally, we found that mtDNA-mediated STING signaling triggered necroptosis through synergistic IFN and TNF-α signaling in primary IECs. Our results indicated that mtDNA-STING signaling can contribute to intestinal I/R injury by promoting IEC necroptosis. STING-mediated both IFN and TNF-α signaling can trigger intestinal nercroptosis.Subject terms: Necroptosis, Cell death and immune response     

Rotenone, a mitochondrial electron transport inhibitor, ameliorates ischemia-reperfusion-induced intestinal mucosal damage in rats

In ischemia-reperfusion (I/R)-induced tissue injury, oxygen radicals can be generated by several mechanisms. One of the important sources of oxygen radicals is thought to be mitochondrial respiration. The aim of this study was to investigate the antioxidative defense effect of the mitochondrial electron transport inhibitor, rotenone using the I/R-induced rat intestinal mucosal injury model in vivo. Intestinal ischemia was induced for 30 min by applying a small clamp to the superior mesenteric artery in rats. Rotenone at a dose of 100 mg/kg was given to rats orally 2 h before the ischemia. Intraluminal hemoglobin and protein levels, the mucosal content of thiobarbituric acid-reactive substances (TBARS), the mucosal myeloperoxidase activity, and the content of inflammatory cytokines (CINC-1, TNF-alpha) were all significantly increased from mean basal levels after 60 min of reperfusion. These increases after I/R were inhibited by treatment with rotenone at a dose of 100 mg/kg. Co-administration with succinate (100 mg/kg), a substrate of the mitochondrial electron transport system, cancelled significant reduction of intraluminal hemoglobin and mucosal TBARS treated with rotenone alone. The results of the present study indicate that rotenone inhibited lipid peroxidation and reduced development of the intestinal mucosal inflammation induced by I/R in rats. This investigation suggests that rotenone has potential as a new therapeutic agent for reperfusion injury.     

Gastrointestinal ischemia-reperfusion injury is lectin complement pathway dependent without involving C1q

Complement activation plays an important role in local and remote tissue injury associated with gastrointestinal ischemia-reperfusion (GI/R). The role of the classical and lectin complement pathways in GI/R injury was evaluated using C1q-deficient (C1q KO), MBL-A/C-deficient (MBL-null), complement factor 2- and factor B-deficient (C2/fB KO), and wild-type (WT) mice. Gastrointestinal ischemia (20 min), followed by 3-h reperfusion, induced intestinal and lung injury in C1q KO and WT mice, but not in C2/fB KO mice. Addition of human C2 to C2/fB KO mice significantly restored GI/R injury, demonstrating that GI/R injury is mediated via the lectin and/or classical pathway. Tissue C3 deposition in C1q KO and WT, but not C2/fB KO, mice after GI/R demonstrated that complement was activated in C1q KO mice. GI/R significantly increased serum alanine aminotransferase, gastrointestinal barrier dysfunction, and neutrophil infiltration into the lung and gut in C1q KO and WT, but not C2/fB KO, mice. MBL-null mice displayed little gut injury after GI/R, but lung injury was present. Addition of recombinant human MBL (rhuMBL) to MBL-null mice significantly increased injury compared with MBL-null mice after GI/R and was reversed by anti-MBL mAb treatment. However, MBL-null mice were not protected from secondary lung injury after GI/R. These data demonstrate that C2 and MBL, but not C1q, are necessary for gut injury after GI/R. Lung injury in mice after GI/R is MBL and C1q independent, but C2 dependent, suggesting a potential role for ficolins in this model.     

Dexmedetomidine alleviates cerebral ischemia-reperfusion injury in rats via inhibition of hypoxia-inducible factor-1α

Dexmedetomidine (Dex) was reported to reduce ischemia-reperfusion (I/R) injury in kidney and brain tissues. Thus, we aimed to study the role and mechanism of Dex in cerebral I/R injury by inhibiting hypoxia-inducible factor-1α (HIF-1α) and apoptosis. First, I/R injury models were established. Six groups were assigned after different treatments: sham, I/R, I/R+Dex, I/R+2-methoxyestradiol (2ME2) (HIF-1α inhibitor), I/R+CoCl ₂ (HIF-1α activator), and I/R+Dex+CoCl ₂ groups. Neurological function, cerebral infarction volume, survival, and apoptosis of brain cells were then analyzed. Besides, immunohistochemistry and Western blot analysis were used to detect the expression of HIF-1α, BCL-2[B-cell leukemia/lymphoma 2] adenovirus E1B interacting protein 3 (BNIP3), B-cell leukemia/lymphoma 2 (BCL2), BCL2[B-cell leukemia/lymphoma 2] associated X (Bax), and cleaved-caspase3 proteins in brain tissues. I/R rats showed cerebral infarction, increased neurological function score, number of terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL)-positive cells and HIF-1α–positive cells as well as decreased neurons. Inhibition of HIF-1α can reduce the apoptosis induced by I/R, and overexpression of HIF-1α can aggravate apoptosis in brain tissue of I/R rats. Furthermore, activation of HIF-1α expression blocks the inhibitory effect of Dex on neuronal apoptosis in I/R rats. Dex may inhibit the neuronal apoptosis of I/R rats by inhibiting the HIF-1α pathway and then improve the cerebral I/R injury in rats.