24-h Reperfusion Research Articles

Melatonin Reduces Aggravation of Renal Ischemia-Reperfusion Injury in Obese Rats by Maintaining Mitochondrial Homeostasis and Integrity through AMPK/PGC-1α/SIRT3/SOD2 Activation.

This study examined the potential benefits of melatonin against renal ischemia and reperfusion (IR) injury in obesity and explored the underlying mechanisms. Obesity was induced in Wistar rats by feeding a high-fat diet for 16 weeks. Three obese groups that underwent renal IR induction (30-min renal ischemia followed by 24-h reperfusion) were randomly assigned to receive melatonin at ischemic onset, reperfusion onset, or pretreatment for 4 weeks before IR induction. Groups of vehicle-treated obese and normal-diet-fed rats that underwent sham or IR induction were also included in the study. The results showed that renal functional and structural impairments after IR incidence were aggravated in obese rats compared to normal-diet-fed rats. The obese-IR rats also exhibited oxidative stress, mitochondrial dysfunction, apoptosis, and mitochondrial dynamics and mitophagy imbalances, which were all considerably improved upon melatonin treatment, irrespective of the treatment time. This study suggests the prophylactic and therapeutic efficacy of melatonin in IR-induced acute kidney injury (AKI) in obese individuals, which may improve the prognosis of AKI in these populations. The benefits of melatonin are likely mediated by the modification of various signaling molecules within the mitochondria that maintain mitochondrial redox balance and lead to the protection of mitochondrial homeostasis and integrity.

Splenic monocytes mediate inflammatory response and exacerbate myocardial ischemia/reperfusion injury in a mitochondrial cell-free DNA-TLR9-NLRP3-dependent fashion.

The spleen contributes importantly to myocardial ischemia/reperfusion (MI/R) injury. Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) recruits inflammasomes, initiating inflammatory responses and mediating tissue injury. We hypothesize that myocardial cell-free DNA (cfDNA) activates the splenic NLRP3 inflammasome during early reperfusion, increases systemic inflammatory response, and exacerbates myocardial infarct. Mice were subjected to 40min of ischemia followed by 0, 1, 5, or 15min, or 24h of reperfusion. Splenic leukocyte adoptive transfer was performed by injecting isolated splenocytes to mice with splenectomy performed prior to left coronary artery occlusion. CY-09 (4mg/kg) was administered 5min before reperfusion. During post-ischemic reperfusion, splenic protein levels of NLRP3, cleaved caspase-1, and interleukin-1β (IL-1β) were significantly elevated and peaked (2.1 ± 0.2-, 3.4 ± 0.4-, and 3.2 ± 0.2-fold increase respectively, p < 0.05) within 5min of reperfusion. In myocardial tissue, NLRP3 was not upregulated until 24h after reperfusion. Suppression by CY09, a specific NLRP3 inflammasome inhibitor, or deficiency of NLRP3 significantly reduced myocardial infarct size (17.3% ± 4.2% and 33.2% ± 1.8% decrease respectively, p < 0.01). Adoptive transfer of NLRP3-/- splenocytes to WT mice significantly decreased infarct size compared to transfer of WT splenocytes (19.1% ± 2.8% decrease, p < 0.0001). NLRP3 was mainly activated at 5min after reperfusion in CD11b+ and LY6G- splenocytes, which significantly increased during reperfusion (24.8% ± 0.7% vs.14.3% ± 0.6%, p < 0.0001). The circulating cfDNA level significantly increased in patients undergoing cardiopulmonary bypass (CPB) (43.3 ± 5.3ng/mL, compared to pre-CPB 23.8 ± 3.5ng/mL, p < 0.01). Mitochondrial cfDNA (mt-cfDNA) contributed to NLRP3 activation in macrophages (2.1 ± 0.2-fold increase, p < 0.01), which was inhibited by a Toll-like receptor 9(TLR9) inhibitor. The NLRP3 inflammasome in splenic monocytes is activated and mediates the inflammatory response shortly after reperfusion onset, exacerbating MI/R injury in mt-cfDNA/TLR9-dependent fashion. The schema reveals splenic NLRP3 mediates the inflammatory response in macrophages and exacerbates MI/R in a mitochondrial cfDNA/ TLR9-dependent fashion.

CD47 blockade enhances phagocytosis of cardiac cell debris by neutrophils.

CD47 is a cell surface protein controlling phagocytotic activity of innate immune cells. CD47 blockade was investigated as an immune checkpoint therapy in cancer treatment, enhancing phagocytosis of tumor cells by macrophages. Anti-CD47 treatment also reduced injury size during reperfused acute myocardial infarction (repAMI) by enhancing phagocytotic acitivity of macrophages. Little is known about the impact of CD47 blockade on neutrophils, representing the main portion of early infiltrating immune cells after repAMI. Therefore, we performed 45min of cardiac ischemia followed by 24h of reperfusion, observing a decreased cardiac injury size measured by triphenyl tetrazolium chloride (TTC) Evan's blue staining. We were able to detect this effect with an innovative three-dimensional method based on light sheet fluorescence microscopy (LSFM). This further allowed us a simultaneous analysis of neutrophil infiltration, showing an unaltered amount of injury-associated neutrophils with reduced cardiac injury volume from repAMI. This observation suggests modulated phagocytosis of cell debris by neutrophils. Therefore, we performed flow cytometry analysis, revealing an increased phagocytotic activity of neutrophils in vitro. These findings highlight that CD47 blockade also enhances phagocytosis of cardiac cell debris by neutrophils, which might be an additional protective effect of anti-CD47 treatment after repAMI.

Blockage of PHLPP1 protects against myocardial ischemia/reperfusion injury in diabetic mice via activation of STAT3 signaling.

Diabetes can exacerbate myocardial ischemia/reperfusion (IR) injury. However, the sensitivity to IR injury and the underlying mechanisms in diabetic hearts remain unclear. Inhibition of PH domain leucine-rich repeating protein phosphatase (PHLPP1) could reduce myocardial IR injury, our previous study demonstrated that the expression of PHLPP1 was upregulated in diabetic myocardial IR model. Thus, this study aimed to investigate the mechanism of PHLPP1 in diabetic myocardial IR injury. Nondiabetic and diabetic C57BL/6 mice underwent 45min of coronary artery occlusion followed by 2h of reperfusion. Male C57BL/6 mice were injected with streptozotocin for five consecutive days to establish a diabetes model. H9c2 cells were exposed to normal or high glucose and subjected to 4h of hypoxia followed by 4h of reoxygenation. Diabetes or hyperglycemia increased postischemic infarct size, cellular injury, release of creatine kinase-MB, apoptosis, and oxidative stress, while exacerbating mitochondrial dysfunction. This was accompanied by enhanced expression of PHLPP1 and decreased levels of p-STAT3 and p-Akt. These effects were counteracted by PHLPP1 knockdown. Moreover, PHLPP1 knockdown resulted in an increase in mitochondrial translocation of p-STAT3 Ser727 and nuclear translocation of p-STAT3 Tyr705 and p-STAT3 Ser727. However, the effect of PHLPP1 knockdown in reducing posthypoxic cellular damage was nullified by either Stattic or LY294002. Additionally, a co-immunoprecipitation assay indicated a direct interaction between PHLPP1 and p-STAT3 Ser727, but not p-STAT3 Tyr705. The abnormal expression of PHLPP1 plays a significant role in exacerbating myocardial IR injury in diabetic mice. Knockdown of PHLPP1 to activate the STAT3 signaling pathway may represent a novel strategy for alleviating myocardial IR injury in diabetes.

Crocetin Suppresses Uterine Ischemia/Reperfusion-induced Inflammation and Apoptosis through the Nrf-2/HO-1 Pathway.

Uterine ischemia/reperfusion (I/R) injury often occurs during many complex surgical procedures, such as uterus transplantation, cesarean, and myomectomy, which may lead to the loss of uterine function and failure of the operation. Crocetin (CRO), as one of the major active constituents from saffron extract, shows protective effects against reactive oxygen species, inflammation, and apoptosis. However, the role of CRO in protecting the uterus against I/R-induced injury has never been investigated. This study aims to clarify the protective role of CRO against I/R injury and the underlying mechanisms. Sprague-Dawley rats were randomly divided into five groups: the control group, I/R group, 20 mg/kg CRO-treated I/R group, 40 mg/kg CRO-treated I/R group, and 80 mg/kg CRO-treated I/R group. Rats were given daily gavages with different doses of CRO or vehicle for five consecutive days. The rat uterine I/R model was created by routine method with 1h ischemia and 3h reperfusion. The serum and uterine tissues were collected, the changes in malondialdehyde (MDA) level and superoxide dismutase (SOD) activity, the mRNA and protein levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and IL-10, the protein levels of B-cell chronic lymphocytic leukemia/lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax), caspase-3, nuclear factor erythroid 2-related factor (Nrf)-2, and heme oxygenase (HO)-1, were measured. The histological changes were examined by HE staining. The number of apoptotic cells was analyzed by flow cytometry. Uterine I/R significantly induced MDA level, suppressed SOD activity, upregulated levels of pro-inflammatory cytokines, down-regulated level of the antiinflammatory cytokine, induced caspase-3-dependent apoptosis, activated the protein expression of Nrf-2 and HO-1, and caused uterine damage. However, pre-administration of CRO effectively reversed I/R-induced above changes and further enhanced Nrf-2/HO- 1 activation in a dose-dependent manner. Pre-administration of CRO effectively alleviates I/R-induced oxidative stress, inflammation, apoptosis, and tissue injury probably through activating the Nrf- 2/HO-1 pathway, suggesting a protective role of CRO in I/R-induced uterus injury.

Trehalose Alleviates Myocardial Ischemia/Reperfusion Injury by Inhibiting NLRP3-Mediated Pyroptosis.

Myocardial ischemia/reperfusion (I/R) injury is a pathological damage secondary to myocardial ischemia that can further aggravate tissue and organ injuries. Therefore, there is an urgent need to develop an effective approach for alleviating myocardial I/R injury. Trehalose (TRE) is a natural bioactive substance that has been shown to have extensive physiological effects in various animals and plants. However, TRE's protective effects against myocardial I/R injury remain unclear. This study aimed to evaluate the protective effect of TRE pre-treatment in mice with acute myocardial I/R injury and to explore the role of pyroptosis in this process. Mice were pre-treated with trehalose (1mg/g) or an equivalent amount of saline solution for 7days. The left anterior descending coronary artery was ligated in mice from the I/R and I/R + TRE groups, followed by 2-h or 24-h reperfusion after 30min. Transthoracic echocardiography was performed to assess cardiac function in mice. Serum and cardiac tissue samples were obtained to examine the relevant indicators. We established an oxygen-glucose deprivation and re-oxygenation model in neonatal mouse ventricular cardiomyocytes and validated the mechanism by which trehalose affects myocardial necrosis via overexpression or silencing of NLRP3. TRE pre-treatment significantly improved cardiac dysfunction and reduced the infarct size in mice after I/R, accompanied by a decrease in the I/R-induced levels of CK-MB, cTnT, LDH, reactive oxygen species, pro-IL-1β, pro-IL-18, and TUNEL-positive cells. Furthermore, TRE intervention suppressed the expression of pyroptosis-related proteins following I/R. TRE attenuates myocardial I/R injury in mice by inhibiting NLRP3-mediated caspase-1-dependent pyroptosis in cardiomyocytes.

Alpha-pinene modulates inflammatory response and protects against brain ischemia via inducible nitric oxide synthase-nuclear factor-kappa B-cyclooxygenase-2 pathway.

Cerebral ischemia-reperfusion leads to brain tissue injury. Inflammation and apoptosis play pivotal roles in the pathology. α-Pinene is an organic compound of many aromatic plants and is known as a potent agent to possess antioxidant, and anti-inflammatory properties. Here, we sought to identify the anti-inflammatory and anti-apoptosis mechanism by which α-Pinene improves brain ischemia injury. Male Wistar rats underwent MCAO surgery for 1h and different doses of alpha-pinene (25, 50, and 100mg/kg) were intraperitoneally injected immediately after reperfusion to test this hypothesis. IV, NDS, gene and protein expression of inducible nitric oxide synthase (iNOS), cyclogenase-2 (COX-2), nuclear factor kappa B (NF-κB) p65, and caspase-3 were assessed 24h after reperfusion. Results demonstrated that NF-κB p65, iNOS, and COX-2 gene and protein expression increased in the hippocampus, cortex, and striatum after 24h of reperfusion, and alpha-pinene significantly inhibited NF-kB p65, iNOS, and COX-2 expression. Also, alpha-pinene significantly reduced the ischemia/reperfusion-induced caspase-3 activation in CA1 area of hippocampus. Results showed that alpha-pinene protects the cerebral against ischemic damage caused by MCAO, and this effect may be through the regulating iNOS -NF-kappa B- COX-2 and caspase-3 inflammatory and apoptotic pathways.

#6496 CYCLIN D1 AMELIORATES ACUTE KIDNEY INJURY BY IMPROVING FATTY ACID OXIDATION VIA AMPK PATHWAY

Abstract Background and Aims Acute Kidney Injury (AKI) is a critical condition that is caused by the absence of oxygen during the acute ischemic phase, leading to energy metabolism disturbance and kidney tubular epithelial cell damage. Fatty Acid Oxidation (FAO) is the main source of energy production of renal proximal tubular epithelial cells. Timely promoting FAO, increasing supplies of energy, and promoting cell proliferation are essential to improve kidney injury. However, there is no clinically recognized effective treatment for this. Cyclin D1(CCND1), a member of the cell cycle family, plays a vital role in cell proliferation. Our previous study showed that CCND1 improved AKI by increasing FAO. This study aimed to investigate the role and molecular basis of CCND1 involvement in fatty acid oxidation of AKI. Method CCND1 was evaluated in human kidney proximal tubular epithelial cells (HK-2 cells) and in male C57BL/6J mice (wild type). We investigated the protective role of CCND1 in AKI using a mouse model of ischemia-reperfusion injury, which was treated by transferring CCND1-expressing plasmids in male C57BL/6J mice (wild type) by ultrasound and microbubble-mediated delivery. Eight-week-old male C57BL/6J mice (wild type) were subjected to bilateral renal artery occlusion for 30min followed by 24h of reperfusion. We evaluated FAO, proliferation, and autophagy in vitro and in vivo. In addition, we evaluated the concentrations of blood urea nitrogen and creatinine, evaluated kidney ultrastructure and so on. Results In vivo studies showed that activation of CCND1 prevented AKI-induced lipid accumulation, kidney tubule injury and kidney function declined after ischemia-reperfusion injury. Compared to test control, the treatment significantly (p&amp;lt;0.05) reduced the concentrations of blood urea nitrogen and creatinine. Kidney-specific overexpression of CCND1 increased FAO, promoted proliferation and reduced apoptosis. Mechanistically, CCND1 activated the AMPK pathway, which increased the expression of phosphorylation AMP activated protein kinase (p-AMPK) and upregulated FAO. On the other hand, inhibiting the expression of CCND1 worsened the impairment of FAO and disturbed energy metabolism. Conclusion CCND1 improved FAO and reduced lipid accumulation through the active AMPK pathway in kidney proximal tubular epithelial cells (PTECs). Hence, restoring of the expression of CCND1 may offer a novel therapeutic strategy for treating AKI.

#5349 CYCLIN D1 AMELIORATES ACUTE KIDNEY INJURY BY IMPROVING FATTY ACID OXIDATION VIA AMPK PATHWAY

Abstract Background and Aims Acute kidney injury (AKI) is a life-threatening condition. The absence of oxygen during the acute ischemic phase would disturb energy metabolism and cause kidney tubular epithelial cell damage. Fatty Acid Oxidation (FAO) is the main source of energy production of renal proximal tubular epithelial cells. Timely promoting FAO, increasing supplies of energy, and promoting cell proliferation are essential to improve kidney injury, but there is no clinically recognized effective treatment for this. Cyclin D1(CCND1), a member of the cell cycle family, plays a vital role in cell proliferation. Our previous study found that CCND1 improved AKI accompanied with increased fatty acid oxidation. Therefore, we investigated the role and molecular basis for CCND1 involvement in fatty acid oxidation of AKI. Method CCND1 was evaluated in AKI in human kidney proximal tubular epithelial cells (HK-2 cells) and male C57BL/6J mice (wild type). The protective role of CCND1 in AKI was investigated in a mouse model of ischemia-reperfusion AKI treated by ultrasound-microbubble-mediated kidney-specifically transferring CCND1-expressing plasmids in male C57BL/6J mice (wild type). Eight-week-old male C57BL/6J mice (wild type) were subjected to bilateral renal artery occlusion for 30min followed by 24h of reperfusion. We evaluated FAO, proliferation, and autophagy in vitro and in vivo. In addition, we evaluated the concentrations of blood urea nitrogen and creatinine, evaluated kidney ultrastructure and so on. Results In vivo studies had shown that activation of CCND1 can prevent AKI-induced lipid accumulation, kidney tubule injury and kidney function declined after ischemia-reperfusion injury. Compared to test control, the treatment significantly (p &amp;lt; 0.05) lowered the concentrations of blood urea nitrogen and creatinine. Kidney specific overexpression of CCND1 promoted FAO, promoted proliferation and reduced apoptosis. Mechanistically, CCND1 activated the AMPK pathway, which increased the expression of phosphorylation AMP activated protein kinase (p-AMPK) and upregulated FAO. On the contrary, inhibiting the expression of CCND1 exacerbated impairment of FAO and disturbed energy metabolism. Conclusion Thus, CCND1 improved FAO and reduced lipid accumulation via active AMPK pathway in kidney proximal tubular epithelial cells (PTECs). Hence, reconstruction of the expression of CCND1 may be a novel therapeutic strategy for treating AKI.

#5330 CYCLIN D1 AMELIORATES ISCHEMIA/REPERFUSION-INDUCED ACUTE KIDNEY INJURY

Abstract Background and Aims Acute kidney injury (AKI) is a life-threatening condition. The absence of oxygen during the acute ischemic phase would disturb energy metabolism and cause kidney tubular epithelial cell damage. Fatty Acid Oxidation (FAO) is the main source of energy production of renal proximal tubular epithelial cells. Timely promoting FAO, increasing supplies of energy, and promoting cell proliferation are essential to improve kidney injury, but there is no clinically recognized effective treatment for this. Cyclin D1(CCND1), a member of the cell cycle family, plays a vital role in cell proliferation. Our previous study found that CCND1 improved AKI accompanied with increased fatty acid oxidation. Therefore, we investigated the role and molecular basis for CCND1 involvement in fatty acid oxidation of AKI. Method CCND1 was evaluated in AKI in human kidney proximal tubular epithelial cells (HK-2 cells) and male C57BL/6J mice (wild type). The protective role of CCND1 in AKI was investigated in a mouse model of ischemia-reperfusion AKI treated by ultrasound-microbubble-mediated kidney-specifically transferring CCND1-expressing plasmids in male C57BL/6J mice (wild type). Eight-week-old male C57BL/6J mice (wild type) were subjected to bilateral renal artery occlusion for 30min followed by 24h of reperfusion. We evaluated FAO, proliferation, and autophagy in vitro and in vivo. In addition, we evaluated the concentrations of blood urea nitrogen and creatinine, evaluated kidney ultrastructure and so on. Results In vivo studies had shown that activation of CCND1 can prevent AKI-induced lipid accumulation, kidney tubule injury and kidney function declined after ischemia-reperfusion injury. Compared to test control, the treatment significantly (p&amp;lt;0.05) lowered the concentrations of blood urea nitrogen and creatinine. Kidney specific overexpression of CCND1 promoted FAO, promoted proliferation and reduced apoptosis. Mechanistically, CCND1 activated the AMPK pathway, which increased the expression of phosphorylation AMP activated protein kinase (p-AMPK) and upregulated FAO. On the contrary, inhibiting the expression of CCND1 exacerbated impairment of FAO and disturbed energy metabolism. Conclusion Thus, CCND1 improved FAO and reduced lipid accumulation via active AMPK pathway in kidney proximal tubular epithelial cells (PTECs). Hence, reconstruction of the expression of CCND1 may be a novel therapeutic strategy for treating AKI.

#5885 HYPOXIA INDUCES COMPLEMENT ACTIVATION ON HUMAN KIDNEY EPITHELIAL CELLS

Abstract Background and Aims Ischemia-reperfusion injury is an inevitable event associated with kidney transplantation (Tx) and has a major impact on short- and long-term graft survival. Proximal tubular epithelial cells are both a source of complement during Tx and a target of complement activation. The normal kidney has a capacity to protect itself from complement activation through cellular expression of complement regulatory proteins. In this study we investigated whether hypoxia and reoxygenation increase C3 deposition and alter complement regulatory protein expression (CD46, CD59 and CD55). Method In vitro, HKC-8 renal proximal tubular epithelial cells were subjected to 24h of hypoxia (1% O2) and then reoxygenated for 4h (O2 = 21%) in the presence of 40% normal human serum. qRT-PCR was used to estimate the level of VEGF-A (as a positive control), C3, CD46, CD59 and CD55 expression. Similar analysis was performed in untreated, normoxic cells. Immunofluorescence staining was used to determine C3 deposition on the cell surface and intensity quantified by ImageJ. Experiments were repeated three times. Results qRT-PCR analysis of HKC-8 cells in hypoxia revealed significant increases in the expression of VEGF-A after 24h (p = 0.0113). C3 expression following hypoxia and reoxygenation increased insignificantly. Increased expression of CD59 with the presence of serum was observed in epithelial cells (p = 0.026). However, no significant change was seen in the expression of CD55 and CD46. Reoxygenation in human serum led to significantly greater deposition of C3 on hypoxic cells compared with normoxic HKC-8 cells (Figure 1, 2). Conclusion Our preliminary data suggests that hypoxia and reoxygenation significantly increases C3 deposition on the proximal tubular cell surface. CD59, as one of the regulators of complement activation is upregulated at mRNA level after hypoxia followed by 4h reperfusion in the presence of serum. These data demonstrate that hypoxia and reoxygenation activate complement system with upregulation of CD59 as a cell defence. However, expression of CD46 and CD55 do not change. Further study is needed to identify the impact of hypoxia on complement regulation in primary epithelial cells and kidney tissues.

Exosomes obtained from adipose mesenchymal stem cells prevent ischemia-reperfusion injury after torsion-detorsion in rat testes.

To investigate the effect of exosomes obtainedfrom adipose-derived mesenchymal stem cells (AD-MSCs) on testicular ischemia-reperfusion (I/R) injury. AD-MSCs from rat adipose tissue were cultured. Characterization of cells was evaluated with CD44, CD90, CD34 and CD45 antibodies. Exosomes from AD-MSCs were obtained with the miRCURYexosomeisolation kit. 21 rats were divided into 3 groups. The I/R model was created as 720° torsion for 4h and reperfusion for 4h. In the Sham group (SG), only scrotal incision was made. 100µl of medium in the torsion-control group (T-CG) and 100µl of exosome in the treatment group (TG) were injected into the testicular parenchyma after detorsion. Johnsen scores of testicles were determined. Apoptosis was evaluated by the TUNEL method. It was observed that the seminiferous tubule structures were partially disrupted in T-CG, but normal in SG and TG. Johnsen scores in SG, T-CG, and TG were 8.64 ± 0.39, 7.71 ± 0.37, and 8.57 ± 0.39, respectively. Apoptotic cell distribution was 11.28 ± 5.25%, 60.58% ± 1.68% and 17.71 ± 8.34% in SG, T-CG and TG, respectively. In both parameters, the difference between SG and TG was insignificant (p > 0.05), the difference between T-CG/TG and SG/T-CG was significant (p < 0.05). Exosomes obtainedfromAD-MSCs are effective in preventing testicular I/R injury. This effect appears to occur because of suppression of apoptotic activity.

Mitoprotective effect of mesenchymal stem cells-derived conditioned medium in myocardial reperfusion injury of aged rats: role of SIRT-1/PGC-1α/NRF-2 network.

The aged myocardium experiences various forms of stress that cause reduction of its tolerance to injury induced by ischemia/reperfusion (I/R). Developing effective cardioprotective modalities to prevent the amplification of I/R injury during aging is under focus of investigation. Mesenchymal stem cells (MSCs) have the ability to regenerate infarcted myocardium mostly by producing multiple secretory factors. This study aimed to explore the mechanisms of mitoprotection by MSCs-conditioned medium (CM) in myocardial I/R injury of aged rats. Male Wistar rats (n = 72, 400-450g, 22-24months old) were randomized into groups with/without I/R and/or MSCs-CM treatment. To establish myocardial I/R injury, the method of LAD occlusion and re-opening was employed. MSCs-CM was administered intramyocardially (150μl) at the onset of reperfusion in recipient group. After 24h reperfusion, myocardial infarct size, LDH level, mitochondrial functional endpoints, expression of mitochondrial biogenesis-associated genes, and the levels of pro-inflammatory cytokines were evaluated. After 28days reperfusion, echocardiographic assessment of cardiac function was performed. MSCs-CM treatment improved myocardial function and decreased infarct size and LDH level in aged I/R rats (P < .05 to P < .001). It also decreased mitochondrial ROS formation, enhanced mitochondrial membrane potential and ATP content, upregulated mitochondrial biogenesis-related genes including SIRT-1, PGC-1α, and NRF-2, and lessened TNF-α, IL-1β, and IL-6 levels (P < .05 to P < .01). MSCs-CM treatment attenuated myocardial I/R injury in aged rats, in part by improving mitochondrial function and biogenesis and restraining inflammatory reaction. the upregulation of SIRT-1/PGC-1α/NRF-2 profiles is a possible target for the mitoprotective effects of MSCs-CM following I/R injury during aging.

6-Shogaol from Dried Ginger Protects against Intestinal Ischemia/Reperfusion by Inhibiting Cell Apoptosis via the BDNF/TrkB/PI3K/AKT Pathway.

Intestinal ischemia-reperfusion (II/R) injury is a common pathological process with high morbidity and mortality. Effective prevention and treatment therapies for II/R are clinically necessary. 6-Shogaol (6-SG), the main active ingredient in dried ginger, behaviors multiple biological activities, including anti-inflammation, antioxidation, and anti-apoptosis. This study aims to elucidate the protective effects and mechanism of 6-SG against II/R-induced injury. Sprague-Dawley rats are pre-treated orally with 6-SG and subjected to II/R injury by clamping superior mesenteric artery for 1h and reperfusion for 2h. Caco-2 cells are challenged by hypoxia/reoxygenation to mimic II/R in vitro. 6-SG pre-treatment protects against II/R injury by reducing intestinal morphological damage and intestinal barrier injury via inhibiting cell apoptosis. Network pharmacology and molecular docking analyses revealthat 6-SG has a high affinity with brain-derived neurotrophic factor (BDNF) formed homodimer or heterodimer with NT4 instead of the monomer, and thus the dimer configuration is stabilized, activating BDNF/TrkB/PI3K/AKT signaling pathway and inhibiting II/R-induced cell apoptosis. The outcome is further validated both in vivo and in vitro. 6-Shogaol protects against II/R injury by inhibiting cell apoptosis through the BDNF/TrkB/PI3K/AKT pathway. This study offers a new understanding of the protection mechanism of 6-SG against II/R-induced injury.

Is aryl hydrocarbon receptor antagonism after ischemia effective in alleviating acute hepatic ischemia-reperfusion injury in rats?

Aryl hydrocarbon receptors (AhRs) have been reported to be important mediators of ischemic injury in the brain. Furthermore, the pharmacological inhibition of AhR activation after ischemia has been shown to attenuate cerebral ischemia-reperfusion (IR) injury. Here, we investigated whether AhR antagonist administration after ischemia was also effective in ameliorating hepatic IR injury. A 70% partial hepatic IR (45-min ischemia and 24-h reperfusion) injury was induced in rats. We administered 6,2′,4′-trimethoxyflavone (TMF, 5 mg/kg) intraperitoneally 10 min after ischemia. Hepatic IR injury was observed using serum, magnetic resonance imaging-based liver function indices, and liver samples. TMF-treated rats showed significantly lower relative enhancement (RE) values and serum alanine aminotransferase (ALT) and aspartate aminotransferase levels than did untreated rats at 3 h after reperfusion. After 24 h of reperfusion, TMF-treated rats had significantly lower RE values, ΔT1 values, serum ALT levels, and necrotic area percentage than did untreated rats. The expression of the apoptosis-related proteins, Bax and cleaved caspase-3, was significantly lower in TMF-treated rats than in untreated rats. This study demonstrated that inhibition of AhR activation after ischemia was effective in ameliorating IR-induced liver injury in rats.

Dexmedetomidine alleviates cerebral ischemia-reperfusion injury via inhibiting autophagy through PI3K/Akt/mTOR pathway

Dexmedetomidine has been shown to protect against cerebral ischemia-reperfusion injury (CIRI). Nevertheless, the precise mechanism is obscure. In order to explore the effect of dexmedetomidine pre-conditioning on autophagy against CIRI in rats, middle cerebral artery occlusion (MCAO) was conducted to establish cerebral ischemia-reperfusion (I/R) model in male SD rats with 2h ischemia and 24h reperfusion. Dexmedetomidine was delivered to rats at 10, 50 and 100µg/kg doses respectively, and LY294002, a PI3K/Akt/mTOR pathway inhibitor, was administered at 10mg/kg intraperitoneally 30min before MCAO. Neurological deficit score was assessed and cerebral infarct size was detected by TTC staining. Morris water maze (MWM) was performed to estimate spatial learning and memory ability. Furthermore, to detect activity of PI3K/Akt/mTOR pathway and autophagy, p-Akt, p-mTOR, Beclin-1 and LC3 were measured by western blot. Our findings revealed that 50 and 100µg/kg of dexmedetomidine pretreatment could improve the neurological deficit score and reduce cerebral infarct size after CIRI, while these effects were markedly suppressed by LY294002. In MWM test, dexmedetomidine was confirmed to shorten escape latency and increase times across platform after CIRI. Nevertheless, LY294002 pretreatment eliminated the improvement of dexmedetomidine on spatial learning and memory ability. Furthermore, dexmedetomidine pretreatment reduced ratios of Beclin-1 and LC3II/LC3I and elevated p-Akt/Akt and p-mTOR/mTOR after CIRI. However, above effects of dexmedetomidine were partly reversed by LY294002. Overall, dexmedetomidine pretreatment exerted neuroprotection against CIRI in rats by attenuating autophagy via the PI3K/Akt/mTOR pathway.

Evaluation of prophylactic efficacy of sodium thiosulfate in combating I/R injury in rat brain: exploring its efficiency further in vascular calcified brain slice model.

Cerebral ischemia reperfusion injury (CIR) is one of the clinical manifestations encountered during the management of stroke. High prevalence of intracranial arterial calcification is reported in stroke patients. However, the impact of vascular calcification (VC) in the outcome of CIR and the efficacy of mechanical preconditioning (IPC) and pharmacological conditioning with sodium thiosulphate (STS) in ameliorating IR remains unclear. Two experimental models namely carotid artery occlusion (n=36) and brain slice models (n=18) were used to evaluate the efficacy of STS in male Wistar rats. IR was inflicted in rat by occluding carotid artery for 30min followed by 24-h reperfusion after STS (100mg/kg) administration. Brain slice model was used to reconfirm the results to account blood brain barrier permeability. Further, brain slice tissue was utilised to evaluate the efficacy of STS in VC rat brain by measuring the histological alterations and biochemical parameters. Pre-treatment of STS prior to CIR in intact animal significantly reduced the IR-associated histopathological alterations in brain, declined oxidative stress and improved the mitochondrial function found to be similar to IPC. Brain slice model data also confirmed the neuroprotective effect of STS similar to IPC in IR challenged tissue slice. Higher tissue injury was noted in VC brain IR tissue than normal IR tissue. Therapeutic efficacy of STS was evident in VC rat brain tissues and normal tissues subjected to IR. On the other hand, IPC-mediated protection was noted only in IR normal and adenine-induced VC brain tissues not in high-fat diet (HFD) induced VC brain tissues. Based on the results, we concluded that similar to IPC, STS was effective in attenuating IR injury in CIR rat brain. Vascular calcification adversely affected the recovery protocol of brain tissues from ischemic insult. STS was found to be an effective agent in ameliorating the IR injury in both adenine and HFD induced vascular calcified rat brain, but IPC-mediated neuroprotection was absent in HFD-induced VC brain tissues.

Effect of the Non-steroidal Anti-inflammatory Drug Diclofenac on Ischemia-Reperfusion Injury in Rat Liver: A Nitric Oxide-Dependent Mechanism.

Ischemia/reperfusion injury (IRI) is an inevitable complication of liver surgery and transplantation. The purpose of this study was to examine the beneficial effects of diclofenac on hepatic IRI and the mechanism behind it. Wistar rats' livers were subjected to warm ischemia for 60min followed by 24h of reperfusion. Diclofenac was administered intravenously 15min before ischemia at 10, 20, and 40mg/kg body weight. To determine the mechanism of diclofenac protection, the NOS inhibitor L-Nitro-arginine methyl ester (L-NAME) was administered intravenously 10min after diclofenac injection (40mg/kg). Liver injury was evaluated by aminotransferases (ALT and AST) activities and histopathological analysis. Oxidative stress parameters (SOD, GPX, MPO, GSH, MDA, and PSH) were also determined. Then, eNOS gene transcription and p-eNOS and iNOS protein expressions were evaluated. The transcription factors PPAR-γ and NF-κB in addition to the regulatory protein IκBα were also investigated. Finally, the gene expression levels of inflammatory (COX-2, IL-6, IL-1β, IL-18, TNF-α, HMGB-1, and TLR-4) and apoptosis (Bcl-2 and Bax) markers were measured. Diclofenac, at the optimal dose of 40mg/kg, decreased liver injury and maintained histological integrity. It also reduced oxidative stress, inflammation, and apoptosis. Its mechanism of action essentially depended on eNOS activation rather than COX-2 inhibition, since pre-treatment with L-NAME abolished all the protective effects of diclofenac. To our knowledge, this is the first study demonstrating that diclofenac protects rat liver against warm IRI through the induction of NO-dependent pathway. Diclofenac reduced oxidative balance, attenuated the activation of the subsequent pro-inflammatory response and decreased cellular and tissue damage. Therefore, diclofenac could be a promising molecule for the prevention of liver IRI.

Low-dose sumatriptan improves the outcome of acute mesenteric ischemia in rats via downregulating kynurenine.

Mesenteric ischemia has remained without effective pharmacological management for many years. Sumatriptan, an abortive medication for migraine and cluster headaches, has potent anti-inflammatory properties and ameliorated organ ischemia in previous animal studies. Similarly, inhibition of the kynurenine pathway ameliorated renal and myocardial ischemia/reperfusion (I/R) in many preclinical studies. Herein, we assessed the effect of sumatriptan on experimental mesenteric I/R and investigated whether kynurenine pathway inhibition is a mechanism underlying its action. Ischemia was induced by ligating the origin of the superior mesenteric artery (SMA) and its anastomosis with the inferior mesenteric artery (IMA) with bulldog clamps for 30min. Ischemia was followed by 1h of reperfusion. Sumatriptan (0.1, 0.3, and 1mg/kg ip) was injected 5min before the reperfusion phase, 1-methyltryptophan (1-MT) (100mg/kg iv) was used to inhibit kynurenine production. At the end of the reperfusion phase, samples were collected from the jejunum of rats for H&E staining and molecular assessments. Sumatriptan improved the integrity of intestinal mucosa after I/R, and 0.1mg/kg was the most effective dose of sumatriptan in this study. Sumatriptan decreased the increased levels of TNF-α, kynurenine, and p-ERK but did not change the decreased levels of NO. Furthermore, sumatriptan significantly increased the decreased ratio of Bcl2/Bax. Similarly, 1-MT significantly decreased TNF-α and kynurenine and protected against mucosal damage. This study demonstrated that sumatriptan has protective effects against mesenteric ischemia and the kynurenine inhibition is potentially involved in this process. Therefore, it can be assumed that sumatriptan has the potential to be repurposed as a treatment for acute mesenteric ischemia.

Global sphingosine-1-phosphate receptor 2 deficiency attenuates neuroinflammation and ischemic-reperfusion injury after neonatal stroke

Arterial ischemic stroke is common in neonates-1 per 2,300-5,000 births-and therapeutic targets remain insufficiently defined. Sphingosine-1-phosphate receptor 2 (S1PR2), a major regulator of the CNS and immune systems, is injurious in adult stroke. Here, we assessed whether S1PR2 contributes to stroke induced by 3h transient middle cerebral artery occlusion (tMCAO) in S1PR2 heterozygous (HET), knockout (KO), and wild type (WT) postnatal day 9 pups. HET and WT of both sexes displayed functional deficits in Open Field test whereas injured KO at 24h reperfusion performed similarly to naives. S1PR2 deficiency protected neurons, attenuated infiltration of inflammatory monocytes, and altered vessel-microglia interactions without reducing increased cytokine levels in injured regions at 72 h. Pharmacologic inhibition of S1PR2 after tMCAO by JTE-013 attenuated injury 72h after tMCAO. Importantly, the lack of S1PR2 alleviated anxiety and brain atrophy during chronic injury. Altogether, we identify S1PR2 as a potential new target for mitigating neonatal stroke.