NADPH oxidase overexpression and mitochondrial OxPhos impairment are more profound in human hearts donated after circulatory death than brain death.

This study investigated cardiac stress and mitochondrial oxidative phosphorylation (OxPhos) in human donation after circulatory death (DCD) hearts regarding warm ischemic time (WIT) and subsequent cold storage and compared them with that of human brain death donor (DBD) hearts. A total of 24 human hearts were procured for the research study-6 in the DBD group and 18 in the DCD group. DCD group was divided into three groups (n = 6) based on different WITs (20, 40, and 60 min). All hearts received del Nido cardioplegia before being placed in normal saline cold storage for 6 h. Left ventricular biopsies were performed at hours 0, 2, 4, and 6. Cardiac stress [nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits: 47-kDa protein of phagocyte oxidase (p47phox), 91-kDa glycoprotein of phagocyte oxidase (gp91phox)] and mitochondrial oxidative phosphorylation [OxPhos, complex I (NADH dehydrogenase) subunit of ETC (CI)-complex V (ATP synthase) subunit of ETC (CV)] proteins were measured in cardiac tissue and mitochondria respectively. Modulation of cardiac stress and mitochondrial dysfunction were observed in both DCD and DBD hearts. However, DCD hearts suffered more cardiac stress (overexpressed NADPH oxidase subunits) and diminished mitochondrial OxPhos than DBD hearts. The severity of cardiac stress and impaired oxidative phosphorylation in DCD hearts correlated with the longer WIT and subsequent cold storage time. More drastic changes were evident in DCD hearts with a WIT of 60 min or more. Activation of NADPH oxidase via overproduction of p47phox and gp91phox proteins in cardiac tissue may be responsible for cardiac stress leading to diminished mitochondrial oxidative phosphorylation. These protein changes can be used as biomarkers for myocardium damage and might help assess DCD and DBD heart transplant suitability.NEW & NOTEWORTHY First human DCD heart research studied cardiac stress and mitochondrial dysfunction concerning WIT and the efficacy of del Nido cardioplegia as an organ procurement solution and subsequent cold storage. Mild to moderate cardiac stress and mitochondrial dysfunction were noticed in DCD hearts with WIT 20 and 40 min and cold storage for 4 and 2 h, respectively. These changes can serve as biomarkers, allowing interventions to preserve mitochondria and extend WIT in DCD hearts.

High shear induces platelet dysfunction leading to enhanced thrombotic propensity and diminished hemostatic capacity.

Thrombosis and bleeding are devastating adverse events in patients supported with blood-contacting medical devices (BCMDs). In this study, we delineated that high non-physiological shear stress (NPSS) caused platelet dysfunction that may contribute to both thrombosis and bleeding. Human blood was subjected to NPSS with short exposure time. Levels of platelet surface GPIbα and GPVI receptors as well as activation level of GPIIb/IIIa in NPSS-sheared blood were examined with flow cytometry. Adhesion of sheared platelets on fibrinogen, von Willibrand factor (VWF), and collagen was quantified with fluorescent microscopy. Ristocetin- and collagen-induced platelet aggregation was characterized by aggregometry. NPSS activated platelets in a shear and exposure time-dependent manner. The number of activated platelets increased with increasing levels of NPSS and exposure time, which corresponded well with increased adhesion of sheared platelets on fibrinogen. Concurrently, NPSS caused shedding of GPIbα and GPVI in a manner dependent on shear and exposure time. The loss of intact GPIbα and GPVI increased with increasing levels of NPSS and exposure time. The number of platelets adhered on VWF and collagen decreased with increasing levels of NPSS and exposure time, respectively. The decrease in the number of platelets adhered on VWF and collagen corresponded well with the loss in GPIbα and GPVI on platelet surface. Both ristocetin- and collagen-induced platelet aggregation in sheared blood decreased with increasing levels of NPSS and exposure time. The study clearly demonstrated that high NPSS causes simultaneous platelet activation and receptor shedding, resulting in a paradoxical effect on platelet function via two distinct mechanisms. The results from the study suggested that the NPSS could induce the concurrent propensity for both thrombosis and bleeding in patients.

Mechanistic insight of platelet apoptosis leading to non-surgical bleeding among heart failure patients supported by continuous-flow left ventricular assist devices.

Non-surgical bleeding (NSB) is the most common clinical complication in heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). In this study, oxidative stress and alteration of signal pathways leading to platelet apoptosis were investigated. Thirty-one HF patients supported by CF-LVADs were divided into bleeder (n = 12) and non-bleeder (n = 19) groups. Multiple blood samples were collected at pre-implant (baseline) and weekly up to 1-month post-implant. A single blood sample was collected from healthy subjects (reference). Production of reactive oxygen species (ROS) in platelets, total antioxidant capacity (TAC), oxidized low-density lipoproteins (oxLDL), expression of Bcl-2 and Bcl-xL, Bax and release of cytochrome c (Cyt.c), platelet mitochondrial membrane potential (Δψ m), activation of caspases, gelsolin cleavage and platelet apoptosis were examined. Significantly elevated ROS, oxLDL and depleted TAC were evident in the bleeder group compared to non-bleeder group (p < 0.05). Platelet pro-survival proteins (Bcl-2, Bcl-xL) were significantly reduced in the bleeder group in comparison to the non-bleeder group (p < 0.05). Translocation of Bax into platelet mitochondria membrane and subsequent release of Cyt.c were more prevalent in the bleeder group. Platelet mitochondrial damage, activation of caspases, gelsolin cleavage, and ultimate platelet apoptosis in the bleeder group were observed. Oxidative stress and activation of both intrinsic and extrinsic pathways of platelet apoptosis may be linked to NSB in CF-LVAD patients. Additionally, biomarkers of oxidative stress, examination of pro-survivals and pro-apoptotic proteins in platelets, mitochondrial damage, caspase activation, and platelet apoptosis may be used to help identify HF patients at high risk of NSB post-implant.

Paradoxical Effect of Nonphysiological Shear Stress on Platelets and von Willebrand Factor.

Blood can become hypercoagulable by shear-induced platelet activation and generation of microparticles. It has been reported that nonphysiological shear stress (NPSS) could induce shedding of platelet receptor glycoprotein (GP) Ibα, which may result in an opposite effect to hemostasis. The aim of this study was to investigate the influence of the NPSS on platelets and von Willebrand factor (vWF). Human blood was exposed to two levels of NPSS (25 Pa, 125 Pa) with an exposure time of 0.5 s, generated by using a novel blood-shearing device. Platelet activation (P-selectin expression, GPIIb/IIIa activation and generation of microparticles) and shedding of three platelet receptors (GPIbα, GPVI, GPIIb/IIIa) in sheared blood were quantified using flow cytometry. Aggregation capacity of sheared blood induced by ristocetin and collagen was evaluated using an aggregometer. Shear-induced vWF damage was characterized with Western blotting. Consistent with the published data, the NPSS caused significantly more platelets to become activated with increasing NPSS level. Meanwhile, the NPSS induced the shedding of platelet receptors. The loss of the platelet receptors increased with increasing NPSS level. The aggregation capacity of sheared blood induced by ristocetin and collagen decreased. There was a loss of high molecular weight multimers (HMWMs) of vWF in sheared blood. These results suggest that the NPSS induced a paradoxical effect. More activated platelets increase the risk of thrombosis, while the reduction in platelet receptors and the loss of HMWM-vWF increased the propensity of bleeding. The finding might provide a new perspective to understand thrombosis and acquired bleeding disorder in patients supported with blood contacting medical devices.

Systemic Inflammatory Response Syndrome in End-Stage Heart Failure Patients Following Continuous-Flow Left Ventricular Assist Device Implantation: Differences in Plasma Redox Status and Leukocyte Activation.

The role of oxidative stress and leukocyte activation has not been elucidated in developing systemic inflammatory response syndrome (SIRS) in heart failure (HF) patients after continuous-flow left ventricular assist device (CF-LVAD) implantation. The objective of this study was to investigate the change of plasma redox status and leukocyte activation in CF-LVAD implanted HF patients with or without SIRS. We recruited 31 CF-LVAD implanted HF patients (16 SIRS and 15 non-SIRS) and 11 healthy volunteers as the control. Pre- and postimplant blood samples were collected from the HF patients. Plasma levels of oxidized low-density lipoprotein (oxLDL), malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD) in erythrocyte, myeloperoxidase (MPO), and polymorphonuclear elastase (PMN-elastase) were measured. The HF patients had a preexisting condition of oxidative stress than healthy controls as evident from the higher oxLDL and MDA levels as well as depleted SOD and TAC. Leukocyte activation in terms of higher plasma MPO and PMN-elastase was also prominent in HF patients than controls. Persistent oxidative stress and reduced antioxidant status were found to be more belligerent in HF patients with SIRS after the implantation of CF-LVAD when compared with non-SIRS patients. Similar to oxidative stress, the activation of blood leukocyte was significantly highlighted in SIRS patients after implantation compared with non-SIRS. We identified that the plasma redox status and leukocyte activation became more prominent in CF-LVAD implanted HF patients who developed SIRS. Our findings suggest that plasma biomarkers of oxidative stress and leukocyte activation may be associated with the development of SIRS after CF-LVAD implant surgery.

Systemic Inflammatory Response Syndrome After Contentious-Flow Left Ventricular Assist Device Implantation and Change in Platelet Mitochondrial Membrane Potential.

BACKGROUND: The objective of this study was to investigate the change of platelet function and platelet mitochondrial membrane potential in contentious-flow left ventricular assist device (CF-LVAD)-implanted heart failure (HF) patients with or without systemic inflammatory response syndrome (SIRS). METHODS AND RESULTS: We recruited 31 CF-LVAD patients (16 SIRS and 15 non-SIRS) and 11 healthy volunteers as control. Pre- and post-implantation blood samples were collected. We used PFA-100 to test platelet functionality. Mitochondrial potential-sensitive dye was used to detect platelet dysfunction (mitochondrial membrane potential; ΔΨm) via flow cytometry. The percentage of depolarized-ΔΨm platelets was found to be a preexisting condition in all HF patients before CF-LVAD implantation compared with control subjects (10.3 ± 6.3% vs 2.8 ± 2.2%; P < .001). As evident from the PFA-100 test, the HF patients who developed SIRS after CF-LVAD implantation had significantly more qualitative platelet defects and thrombocytopathies compared with baseline. After implantation, the depolarized platelets in the SIRS patients increased by 2-fold compared with baseline (18.2 ± 8.4% vs 9.0 ± 6.6%; P < .01); whereas no change was noticed in the non-SIRS patients (10.9 ± 6.2% vs 11.7 ± 5.8%; P = .75). CONCLUSIONS: We identified that platelet function and mitochondrial damage were enhanced in CF-LVAD patients with SIRS. Our findings suggest that depolarization of mitochondrial membrane potential is associated with SIRS after CF-LVAD implantation surgery.

Activation and shedding of platelet glycoprotein IIb/IIIa under non-physiological shear stress.

The purpose of this study was to investigate the influence of non-physiological high shear stress on activation and shedding of platelet GP IIb/IIIa receptors. The healthy donor blood was exposed to three levels of high shear stresses (25, 75, 125 Pa) from the physiological to non-physiological status with three short exposure time (0.05, 0.5, 1.5 s), created by a specific blood shearing system. The activation and shedding of the platelet GPIIb/IIIa were analyzed using flow cytometry and enzyme-linked immunosorbent assay. In addition, platelet P-selectin expression of sheared blood, which is a marker for activated platelets, was also analyzed. The results from the present study showed that the number of activated platelets, as indicated by the surface GPIIb/IIIa activation and P-selectin expression, increased with increasing the shear stress level and exposure time. However, the mean fluorescence of GPIIb/IIIa on the platelet surface, decreased with increasing the shear stress level and exposure time. The reduction of GPIIb/IIIa on the platelet surface was further proved by the reduction of further activated platelet GPIIb/IIIa surface expression induced by ADP and the increase in GPIIb/IIIa concentration in microparticle-free plasma with increasing the applied shear stress and exposure time. It is clear that non-physiological shear stress induce a paradoxical phenomenon, in which both activation and shedding of the GPIIb/IIIa on the platelet surface occur simultaneously. This study may offer a new perspective to explain the reason of both increased thrombosis and bleeding events in patients implanted with high shear blood-contacting medical devices.

Intraplatelet reactive oxygen species, mitochondrial damage and platelet apoptosis augment non-surgical bleeding in heart failure patients supported by continuous-flow left ventricular assist device.

Non-surgical bleeding (NSB) is the most common clinical complication among heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). Understanding the role of platelet functionality contributing to NSB after CF-LVAD implantation is crucial for prevention and management of this adverse event. The aim of this study was to examine the role of intraplatelet reactive oxygen species (ROS) and platelet damage on the incidence of bleeding events after CF-LVAD implantation in HF patients. We recruited 25 HF patients implanted with CF-LVADs and 11 healthy volunteers as the control. Intraplatelet ROS generation, platelet mitochondrial damage and platelet apoptosis were quantified by flow cytometry. Among 25 patients, 8 patients developed non-surgical bleeding within one month after CF-LVAD implantation. Intraplatelet ROS, depolarized and apoptotic platelet were found to be pre-existing conditions in all baseline samples of the 25 HF patients when compared to the healthy volunteers. There was no significant difference in the levels of ROS between the non-bleeder and the bleeder groups prior to CF-LVAD implantation, although we noticed 2-fold and 1.5-fold rise in depolarized and apoptotic platelets, respectively, in the bleeder group compared to those in the non-bleeder group. Post implant levels of intraplatelet ROS, depolarized and apoptotic platelets increased and remained elevated in the bleeder group, whereas periodic decreases were noticed in the non-bleeder group, suggesting the potential role of platelet damage on bleeding incidence. ROS generation after CF-LVAD implantation positively associated with platelet apoptosis (ρ = 0.4263, p = 0.0023) and depolarized platelets (ρ = 0.4774, p = 0.0002), especially the latter. In conclusion, elevated intraplatelet ROS and platelet damage may be linked to the NSB among HF patients supported by CF-LVAD. These results provide mechanistic insights into the bleeding complication in patients with CF-LVAD support.

Quantification of Shear-Induced Platelet Activation: High Shear Stresses for Short Exposure Time.

Thrombosis and thromboembolism are the life-threatening clinical complications for patients supported or treated with prosthetic cardiovascular devices. The high mechanical shear stress within these devices is believed to be the major contributing factor to cause platelet activation (PA) and function alteration, leading to thrombotic events. There have been limited quantitative data on how the high mechanical shear stress causes platelet activation. In this study, shear-induced PA in the ranges of well-defined shear stress and exposure time relevant to cardiovascular devices was quantitatively characterized for human blood using two novel flow-through Couette-type blood shearing devices. Four markers of platelet activation-surface P-selectin (CD62p), platelet-derived microparticles (PMPs), platelet-monocyte aggregation (PMA), and soluble P-selectin-were measured by flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. The results indicated that PA induced by high shear stresses with short exposure time could be reliably detected with surface P-selectin, and, to a lesser extent, PMPs rather than soluble P-selectin. It was also verified that PMA can be a highly sensitive indirect marker of platelet activation. The quantitative relationship between percentage of activated platelets indicated by surface P-selectin expression and shear stress/exposure time follows well the power law functional form. The coefficients of the power law models of PA based on surface P-selectin expression were derived.

Kidney Function Trajectories and Right Heart Failure Following LVAD Implantation.

BACKGROUND: Preoperative kidney dysfunction is a risk factor for right heart failure (RHF) after implantation of a left ventricular assist device (LVAD). However, characteristic kidney function trajectories before and after post-LVAD RHF are uncertain, so we investigated this. METHODS AND RESULTS: We identified individuals who received primary continuous-flow LVAD implantation from July 1, 2014 to December 31, 2017 in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) data set. Incident RHF was ascertained using the INTERMACS definition at 1 and 3 months and classified as transient or persistent. Kidney function trajectories before and after RHF onset, and relationships of baseline kidney function with RHF risk at the different time points, were assessed. We identified 8076 LVAD recipients who met inclusion criteria. Incident RHF was present at 1 month in 26.4%. There were 4850 individuals with follow-up at 3 months, with incident RHF in 4.2%. Kidney function trajectories differed from pre-LVAD implantation to 1-month follow-up by RHF category, with those developing persistent RHF having no improvement in baseline kidney function. For trajectories before the 3-month RHF ascertainment time, the shape was similar for those with and without RHF, with lower estimated glomerular filtration rate levels among those who developed RHF. Baseline estimated glomerular filtration rate levels below the normal range were associated with higher risk of RHF at 1 and 3 months. CONCLUSIONS: In LVAD recipients, preimplantation kidney function and subsequent kidney function trajectories differed substantially by RHF at 1 and 3 months postimplantation, even after adjustment for several confounders. This may demonstrate bidirectional associations between kidney function and right ventricular function in LVAD recipients.

Myocardial edema, inflammation, and injury in human heart donated after circulatory death are sensitive to warm ischemia and subsequent cold storage.

BACKGROUND: Single-dose del Nido solution was recently used in human donation after circulatory death (DCD) heart procurement. We compared the effect of del Nido cardioplegia on myocardial edema, inflammatory response, and injury in human DCD hearts and human donation after brain death (DBD) hearts with different warm ischemic times (WIT) and subsequent cold saline storage times (CST). METHODS: A total of 24 human hearts, including 6 in the DBD group and 18 in the DCD group-were procured for the research study. The DCD group was divided into 3 subgroups based on WIT: 20, 40, and ≥60 minutes. All hearts received 1 L of del Nido cardioplegia before being placed in cold saline for 6 hours. Left ventricular biopsies were performed at 0, 2, 4, and 6 hours. Temporal changes in myocardial edema, inflammatory cytokines (TNF-α, IL-6, and IL-1ß), and histopathology injury scores were compared between the DBD and DCD groups. RESULTS: DCD hearts showed more profound changes in myocardial edema, inflammation, and injury than DBD hearts at baseline and subsequent CST. The DCD heart with WIT of 20 and 40 minutes with CST of 4 and 2 hours, respectively, appeared to have limited myocardial edema, inflammation, and injury. DCD hearts with WIT ≥60 minutes showed severe myocardial edema, inflammation, and injury at baseline and subsequent CST. CONCLUSIONS: Single-dose cold del Nido cardioplegia and subsequent cold normal saline storage can preserve both DCD and DBD hearts. DCD hearts have been shown to be able to tolerate a WIT of 20 minutes and subsequent CST of 4 hours without experiencing significant myocardial edema, inflammation, and injury.

Distinctive kidney function trajectories following left ventricular assist device implantation.

BACKGROUND: The aim of this study was to assess for distinct kidney function trajectories following left ventricular assist device (LVAD) placement. Cohort studies of LVAD recipients demonstrate that kidney function tends to increase early after LVAD placement, followed by decline and limited sustained improvement. Inter-individual differences in kidney function response may be obscured. METHODS: We identified continuous flow LVAD implantations in US adults (2016-2017) from INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support). Primary outcomes were estimated glomerular filtration rate (eGFR) trajectories pre-implantation to ∼12 months. Latent class mixed models were applied to primary and validation samples. Clinical differences among trajectory groups were investigated. RESULTS: Among 4,615 LVAD implantations, 5 eGFR trajectory groups were identified. The 2 largest groups (Groups 1 and 2) made up >80% of the cohort, and were similar to group average trajectories previously reported, with early eGFR rise followed by decline and stabilization. Three novel trajectory groups were found: worsening followed by sustained low kidney function (Group 3, 10.1%), sustained improvement (Group 4, 3.3%), and worsening followed by variation (Group 5, 1.7%). These groups differed in baseline characteristics and outcomes. Group 4 was younger and had more cardiogenic shock and pre-implantation dialysis; Group 3 had higher rates of pre-existing chronic kidney disease, along with older age. CONCLUSIONS: Novel eGFR trajectories were identified in a national cohort, possibly representing distinct cardiorenal processes. Type 1 cardiorenal syndrome may have been predominant in Group 4, and parenchymal kidney disease may have been predominant in Group 3.

Indoor air pollution from biomass burning activates Akt in airway cells and peripheral blood lymphocytes: a study among premenopausal women in rural India.

Biomass burning is a major source of indoor air pollution in rural India. The authors investigated in this study whether cumulative exposures to biomass smoke cause activation of the serine/threonine kinase Akt in airway cells and peripheral blood lymphocytes (PBL). For this, the authors enrolled 87 premenopausal (median age 34 years), nonsmoking women who used to cook with biomass (wood, dung, crop wastes) and 85 age-matched control women who cooked with cleaner fuel liquefied petroleum gas. Immunocytochemical and immunoblotting assays revealed significantly higher levels of phosphorylated forms of Akt protein (p-Akt(ser473) and p-Akt(thr308)) in PBL, airway epithelial cells, alveolar macrophages, and neutrophils in sputum of biomass-using women than control. Akt activation in biomass users was associated with marked rise in generation of reactive oxygen species and concomitant depletion of superoxide dismutase. Measurement of particulate matter having a diameter of less than 10 and 2.5 µm in indoor air by real-time aerosol monitor showed 2 to 4 times more particulate pollution in biomass-using households, and Akt activation was positively associated with particulate pollution after controlling potential confounders. The findings suggest that chronic exposure to biomass smoke activates Akt, possibly via generation of oxidative stress.

Management of Antiplatelet Therapy During Continuous-Flow Left Ventricular Assist Device Support After Thrombotic Hemorrhagic Events.

Hemorrhagic or thrombotic events are common complications in heart failure patients with continuous-flow left ventricular assist device (CF-LVAD) support. Aim of this study is to investigate the effect of change in antiplatelet therapy after thrombotic or hemorrhagic events in patients with CF-LVAD support. A total of 231 CF-LVAD patients were included in this study. Patients with CF-LVAD were categorized into three groups: (1) high antiplatelet regimen as control group (aspirin [ASA] 325 mg; n = 115), (2) low antiplatelet regimen (ASA 81 mg; n = 82), started after hemorrhagic complications, and (3) double antiplatelet therapy (ASA/clopidogrel; n = 34) started after thrombotic complications. In our analysis, indications for low antiplatelet therapy were gastrointestinal (GI) bleeding (36%), hemorrhagic stroke (8%), and epistaxis (9%). Freedom from major bleeding events after changing therapy was comparable at 1 year for all three groups respectively 96%, 97%, and 91% (log rank = 0.421). Major indications for double antiplatelet therapy were pump thrombosis (15%) and coronary artery stent placement (2.5%). Freedom from thrombotic events after changing therapy was comparable at 1 year for groups 1, 2, and 3, respectively, 97%, 98%, and 91% (log rank = 0.317). Logistic regression shows that Heartmate II patients required more antiplatelet therapy changes compared with HeartWare (odds ratio [OR]: 3.611, 95% confidence interval [CI]: 1.8-6.9; p = 0.0001). HeartMate II required more adjustment of antiplatelet therapy during follow-up. Reducing or increasing antithrombotic therapies in response to major thrombotic hemorrhagic events in CF-LVAD patients is a safe strategy to avoid recurrences.

Tetrahydrocurcumin epigenetically mitigates mitochondrial dysfunction in brain vasculature during ischemic stroke.

The objectives of this study are to identify the mechanism of mitochondrial dysfunction during cerebral ischemic/reperfusion (I/R) injury and the therapeutic potential of tetrahydrocurcumin (THC) to mitigate mitochondrial dysfunction in experimental stroke model. In our study, 8-10 weeks old male C57BL/6 wild-type mice were subjected to middle cerebral artery occlusion (MCAO) for 40 min, followed by reperfusion for 72 h. THC (25mg/kg-BW/day) was injected intraperitoneally once daily for 3 days after 4 h of ischemia. The experimental groups were: (i) sham, (ii) I/R and (iii) I/R + THC. We noticed that THC treatment in ischemic mice significantly improved the functional capacity and motor co-ordination along with reduced neuroscore, infarct volume, brain edema and microvascular leakage in brain parenchyma. The study revealed that level of total homocysteine (tHcy), homocysteine metabolizing enzymes, mitochondrial oxidative stress were significantly altered in I/R mice compared to sham. We also observed alteration in mitochondrial transition pore, ATP production and O2 consumption in the ischemic brain as compared to sham. Further, elevated matrix metalloproteinases-9 (MMP-9) activity and reduced tight junction protein expressions intensified the brain vascular impairment in I/R mice compared to sham. Interestingly, we found that levels of mitophagy markers, fusion and fission proteins were significantly altered. However THC treatment in I/R mice almost normalized the above functional and molecular changes. Mechanistic study demonstrated that DNA Methyltransferase 1 (DNMT1) expression was higher and was associated with reduced mitochondrial tissue inhibitor of metalloproteinases 2 (TIMP-2) expression through hyper-methylation of CpG island of TIMP-2 promoter in I/R mice compared to sham. However, administration of epigenetic inhibitor, 5-Azacytidine (5-Aza) abrogated I/R induced hyper-methylation of TIMP-2 promoter and maintaining the extracellular matrix (ECM) integrity. In conclusion, this study suggests that THC epigenetically ameliorates mitochondrial dysfunction in brain vasculature during Ischemic Stroke.

Exercise Mitigates Alcohol Induced Endoplasmic Reticulum Stress Mediated Cognitive Impairment through ATF6-Herp Signaling.

Chronic ethanol/alcohol (AL) dosing causes an elevation in homocysteine (Hcy) levels, which leads to the condition known as Hyperhomocysteinemia (HHcy). HHcy enhances oxidative stress and blood-brain-barrier (BBB) disruption through modulation of endoplasmic reticulum (ER) stress; in part by epigenetic alternation, leading to cognitive impairment. Clinicians have recommended exercise as a therapy; however, its protective effect on cognitive functions has not been fully explored. The present study was designed to observe the protective effects of exercise (EX) against alcohol-induced epigenetic and molecular alterations leading to cerebrovascular dysfunction. Wild-type mice were subjected to AL administration (1.5 g/kg-bw) and subsequent treadmill EX for 12 weeks (5 day/week@7-11 m/min). AL affected mouse brain through increases in oxidative and ER stress markers, SAHH and DNMTs alternation, while decreases in CBS, CSE, MTHFR, tight-junction proteins and cellular H2S levels. Mechanistic study revealed that AL increased epigenetic DNA hypomethylation of Herp promoter. BBB dysfunction and cognitive impairment were observed in the AL treated mice. AL mediated transcriptional changes were abolished by administration of ER stress inhibitor DTT. In conclusion, exercise restored Hcy and H2S to basal levels while ameliorating AL-induced ER stress, diminishing BBB dysfunction and improving cognitive function via ATF6-Herp-signaling. EX showed its protective efficacy against AL-induced neurotoxicity.

Association of Oxidative Stress and Platelet Receptor Glycoprotein GPIbα and GPVI Shedding During Nonsurgical Bleeding in Heart Failure Patients With Continuous-Flow Left Ventricular Assist Device Support.

Nonsurgical bleeding (NSB) in heart failure (HF) patients with continuous-flow left ventricular assist device (CF-LVAD) support is the most common clinical complication. The aim of this study was to investigate the association between oxidative stress and platelet glycoproteins GPIbα and GPVI shedding on the incidence of NSB in CF-LVAD patients. Fifty-one HF patients undergoing CF-LVAD implantation and 11 healthy volunteers were recruited. Fourteen patients developed NSB (bleeder group) during 1 month follow-up duration, while others were considered nonbleeder group (n = 37). Several biomarkers of oxidative stress were quantified at baseline and weekly intervals in all patients. Surface expression and plasma elements of platelet receptor glycoproteins GPIbα and GPVI were measured. Oxidative stress biomarkers and platelet GPIbα and GPVI receptor-shedding (decreased surface expression and higher plasma levels) were found to be preexisting conditions in baseline samples of both groups of HF patients when compared with healthy volunteers. Significantly elevated oxidative stress biomarkers and platelet glycoprotein receptor shedding were observed in postimplant bleeder group temporarily when compared with nonbleeder group. Strong significant associations between biomarkers of oxidative stress and platelet glycoprotein receptor shedding were observed, suggesting a possible role of oxidative stress in platelet integrin shedding leading to NSB in CF-LVAD patients. Receiver operating characteristic analyses of GPIbα and GPVI indicated that the likelihood of NSB had a predictive power of bleeding complication in CF-LVAD patients. In conclusion, elevated oxidative stress may play a role in GPIbα and GPVI shedding in the event of NSB. Thus, oxidative stress and GPIbα and GPVI shedding may be used as potential biomarkers for bleeding risk stratification in those patients.

Infection, Oxidative Stress, and Changes in Circulating Regulatory T Cells of Heart Failure Patients Supported by Continuous-Flow Ventricular Assist Devices.

The objective of this study was to investigate the changes in oxidative stress (OS) and circulating regulatory T cells (Tregs) of the immune system in patients supported by continuous-flow ventricular assist device (CF-VAD) with or without infection. We recruited 16 CF-VAD patients (5 with infection and 11 without infection) and 7 healthy volunteers. Generation of reactive oxygen species (ROS) from lymphocytes, superoxide dismutase (SOD) in erythrocyte, total antioxidant capacity (TAC), and oxidized low-density lipoprotein (oxLDL) in plasma were measured. Circulating Tregs were evaluated by flow cytometry. Heart failure (HF) patients had elevated OS than healthy volunteers as evident from higher lymphocyte ROS, elevated oxLDL, as well as depleted SOD and TAC levels. At baseline, HF patients had decreased percentage of Tregs (5.12 ± 1.5% vs. 8.14 ± 3.01%, p < 0.01) when compared with healthy volunteers. Postimplant patients with infection illustrated 35% and 44% rise in ROS and oxLDL, respectively, 31% decrease in TAC, and marked rise in percentage of Tregs (14.27 ± 3.17% vs. 9.38 ± 3.41%, p < 0.01) when compared with the patients without infection. Elevated OS and rise in Tregs were more prominent in CF-VAD patients with infection. In conclusion, OS and compromised immune system may be important indicators of systemic response of the body to CF-VAD among HF patients with infection.