Browsing by Subject "Reperfusion Injury"
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Item Open Access A novel injury site-natural antibody targeted complement inhibitor protects against lung transplant injury.(American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, 2021-06) Li, Changhai; Patel, Kunal; Tu, Zhenxiao; Yang, Xiaofeng; Kulik, Liudmila; Alawieh, Ali; Allen, Patterson; Cheng, Qi; Wallace, Caroline; Kilkenny, Jane; Kwon, Jennie; Gibney, Barry; Cantu, Edward; Sharma, Ashish; Pipkin, Mauricio; Machuca, Tiago; Emtiazjoo, Amir; Goddard, Martin; Holers, V Michael; Nadig, Satish; Christie, Jason; Tomlinson, Stephen; Atkinson, CarlComplement is known to play a role in ischemia and reperfusion injury (IRI). A general paradigm is that complement is activated by self-reactive natural IgM antibodies (nAbs), after they engage postischemic neoepitopes. However, a role for nAbs in lung transplantation (LTx) has not been explored. Using mouse models of LTx, we investigated the role of two postischemic neoepitopes, modified annexin IV (B4) and a subset of phospholipids (C2), in LTx. Antibody deficient Rag1-/- recipient mice were protected from LTx IRI. Reconstitution with either B4 or C2nAb restored IRI, with C2 significantly more effective than B4 nAb. Based on these information, we developed/characterized a novel complement inhibitor composed of single-chain antibody (scFv) derived from the C2 nAb linked to Crry (C2scFv-Crry), a murine inhibitor of C3 activation. Using an allogeneic LTx, in which recipients contain a full nAb repertoire, C2scFv-Crry targeted to the LTx, inhibited IRI, and delayed acute rejection. Finally, we demonstrate the expression of the C2 neoepitope in human donor lungs, highlighting the translational potential of this approach.Item Open Access Activation of the ATF6 (Activating Transcription Factor 6) Signaling Pathway in Neurons Improves Outcome After Cardiac Arrest in Mice.(Journal of the American Heart Association, 2021-06-11) Shen, Yuntian; Li, Ran; Yu, Shu; Zhao, Qiang; Wang, Zhuoran; Sheng, Huaxin; Yang, WeiBackground Ischemia/reperfusion injury impairs proteostasis, and triggers adaptive cellular responses, such as the unfolded protein response (UPR), which functions to restore endoplasmic reticulum homeostasis. After cardiac arrest (CA) and resuscitation, the UPR is activated in various organs including the brain. However, the role of the UPR in CA has remained largely unknown. Here we aimed to investigate effects of activation of the ATF6 (activating transcription factor 6) UPR branch in CA. Methods and Results Conditional and inducible sATF6-KI (short-form ATF6 knock-in) mice and a selective ATF6 pathway activator 147 were used. CA was induced in mice by KCl injection, followed by cardiopulmonary resuscitation. We first found that neurologic function was significantly improved, and neuronal damage was mitigated after the ATF6 pathway was activated in neurons of sATF6-KI mice subjected to CA/cardiopulmonary resuscitation. Further RNA sequencing analysis indicated that such beneficial effects were likely attributable to increased expression of pro-proteostatic genes regulated by ATF6. Especially, key components of the endoplasmic reticulum-associated degradation process, which clears potentially toxic unfolded/misfolded proteins in the endoplasmic reticulum, were upregulated in the sATF6-KI brain. Accordingly, the CA-induced increase in K48-linked polyubiquitin in the brain was higher in sATF6-KI mice relative to control mice. Finally, CA outcome, including the survival rate, was significantly improved in mice treated with compound 147. Conclusions This is the first experimental study to determine the role of the ATF6 UPR branch in CA outcome. Our data indicate that the ATF6 UPR branch is a prosurvival pathway and may be considered as a therapeutic target for CA.Item Open Access Chemogenetics-mediated acute inhibition of excitatory neuronal activity improves stroke outcome.(Experimental neurology, 2020-04) Wang, Ya-Chao; Galeffi, Francesca; Wang, Wei; Li, Xuan; Lu, Liping; Sheng, Huaxin; Hoffmann, Ulrike; Turner, Dennis A; Yang, WeiBackground and purpose
Ischemic stroke significantly perturbs neuronal homeostasis leading to a cascade of pathologic events causing brain damage. In this study, we assessed acute stroke outcome after chemogenetic inhibition of forebrain excitatory neuronal activity.Methods
We generated hM4Di-TG transgenic mice expressing the inhibitory hM4Di, a Designer Receptors Exclusively Activated by Designer Drugs (DREADD)-based chemogenetic receptor, in forebrain excitatory neurons. Clozapine-N-oxide (CNO) was used to activate hM4Di DREADD. Ischemic stroke was induced by transient occlusion of the middle cerebral artery. Neurologic function and infarct volumes were evaluated. Excitatory neuronal suppression in the hM4Di-TG mouse forebrain was assessed electrophysiologically in vitro and in vivo, based on evoked synaptic responses, and in vivo based on occurrence of potassium-induced cortical spreading depolarizations.Results
Detailed characterization of hM4Di-TG mice confirmed that evoked synaptic responses in both in vitro hippocampal slices and in vivo motor cortex were significantly reduced after CNO-mediated activation of the inhibitory hM4Di DREADD. Further, CNO treatment had no obvious effects on physiology and motor function in either control or hM4Di-TG mice. Importantly, hM4Di-TG mice treated with CNO at either 10 min before ischemia or 30 min after reperfusion exhibited significantly improved neurologic function and smaller infarct volumes compared to CNO-treated control mice. Mechanistically, we showed that potassium-induced cortical spreading depression episodes were inhibited, including frequency and duration of DC shift, in CNO-treated hM4Di-TG mice.Conclusions
Our data demonstrate that acute inhibition of a subset of excitatory neurons after ischemic stroke can prevent brain injury and improve functional outcome. This study, together with the previous work in optogenetic neuronal modulation during the chronic phase of stroke, supports the notion that targeting neuronal activity is a promising strategy in stroke therapy.Item Open Access Donor pretreatment with nebulized complement C3a receptor antagonist mitigates brain-death induced immunological injury post-lung transplant.(American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons, 2018-10) Cheng, Qi; Patel, Kunal; Lei, Biao; Rucker, Lindsay; Allen, D Patterson; Zhu, Peng; Vasu, Chentha; Martins, Paulo N; Goddard, Martin; Nadig, Satish N; Atkinson, CarlDonor brain death (BD) is an inherent part of lung transplantation (LTx) and a key contributor to ischemia-reperfusion injury (IRI). Complement activation occurs as a consequence of BD in other solid organ Tx and exacerbates IRI, but the role of complement in LTx has not been investigated. Here, we investigate the utility of delivering nebulized C3a receptor antagonist (C3aRA) pretransplant to BD donor lungs in order to reduce post-LTx IRI. BD was induced in Balb/c donors, and lungs nebulized with C3aRA or vehicle 30 minutes prior to lung procurement. Lungs were then cold stored for 18 hours before transplantation into C57Bl/6 recipients. Donor lungs from living donors (LD) were removed and similarly stored. At 6 hours and 5 days post-LTx, recipients of BD donor lungs had exacerbated IRI and acute rejection (AR), respectively, compared to recipients receiving LD lungs, as determined by increased histopathological injury, immune cells, and cytokine levels. A single pretransplant nebulized dose of C3aRA to the donor significantly reduced IRI as compared to vehicle-treated BD donors, and returned IRI and AR grades to that seen following LD LTx. These data demonstrate a role for complement inhibition in the amelioration of IRI post-LTx in the context of donor BD.Item Open Access Emphysema-associated Autoreactive Antibodies Exacerbate Post-Lung Transplant Ischemia-Reperfusion Injury.(American journal of respiratory cell and molecular biology, 2019-06) Patel, Kunal J; Cheng, Qi; Stephenson, Sarah; Allen, D Patterson; Li, Changhai; Kilkenny, Jane; Finnegan, Ryan; Montalvo-Calero, Valeria; Esckilsen, Scott; Vasu, Chentha; Goddard, Martin; Nadig, Satish N; Atkinson, CarlChronic obstructive pulmonary disease-associated chronic inflammation has been shown to lead to an autoimmune phenotype characterized in part by the presence of lung autoreactive antibodies. We hypothesized that ischemia-reperfusion injury (IRI) liberates epitopes that would facilitate preexisting autoantibody binding, thereby exacerbating lung injury after transplant. We induced emphysema in C57BL/6 mice through 6 months of cigarette smoke (CS) exposure. Mice with CS exposure had significantly elevated serum autoantibodies compared with non-smoke-exposed age-matched (NS) mice. To determine the impact of a full preexisting autoantibody repertoire on IRI, we transplanted BALB/c donor lungs into NS or CS recipients and analyzed grafts 48 hours after transplant. CS recipients had significantly increased lung injury and immune cell infiltration after transplant. Immunofluorescence staining revealed increased IgM, IgG, and C3d deposition in CS recipients. To exclude confounding alloreactivity and confirm the role of preexisting autoantibodies in IRI, syngeneic Rag1-/- (recombination-activating protein 1-knockout) transplants were performed in which recipients were reconstituted with pooled serum from CS or NS mice. Serum from CS-exposed mice significantly increased IRI compared with control mice, with trends in antibody and C3d deposition similar to those seen in allografts. These data demonstrate that pretransplant CS exposure is associated with increased IgM/IgG autoantibodies, which, upon transplant, bind to the donor lung, activate complement, and exacerbate post-transplant IRI.Item Open Access Lack of evidence for a remote effect of renal ischemia/reperfusion acute kidney injury on outcome from temporary focal cerebral ischemia in the rat.(Journal of cardiothoracic and vascular anesthesia, 2013-02) Yates, RB; Sheng, H; Sakai, H; Kleven, DT; Desimone, NA; Stafford Smith, M; Warner, DSObjective
Acute kidney injury (AKI) and ischemic stroke may occur in the same cardiac surgical patient. It is not known if an interaction exists between these organ injuries. Isolated renal ischemia/reperfusion is associated with dysfunction in remote, otherwise normal organs, including the brain. In a rat model of simultaneous bilateral renal artery occlusion (BRAO) and middle cerebral artery occlusion (MCAO), the authors tested the hypothesis that AKI would worsen experimental stroke outcome.Design
Sixty thermoregulated anesthetized rats were randomized to (1) 40-minute BRAO, (2) 80-minute MCAO, or (3) simultaneous BRAO + MCAO. Serum creatinine was measured at baseline and 2 and 7 days after organ reperfusion. Neurologic function and brain and kidney histologies were measured on day 7. In a parallel study, serum cytokines were measured over 16 hours.Setting
Laboratory.Participants
Male Wistar rats.Interventions
Combined or isolated BRAO and MCAO.Measurements and main results
AKI was similar between the BRAO and BRAO + MCAO groups, with greater 48-hour creatinine increases (p < 0.02) and renal histopathologic scores (p < 0.001) in these groups than with MCAO alone. Neurologic scores correlated with cerebral infarct size (p = 0.0001). There were no differences in neurologic score (p = 0.53) and cerebral infarct volume (p = 0.21) between the MCAO and BRAO + MCAO groups. There was no association between cerebral infarct size or neurologic score and 48-hour creatinine increase. Interleukin-6 was increased during reperfusion (p < 0.0001), but a difference among groups was absent (p = 0.41).Conclusions
In contrast to the effects reported for AKI on normal remote organs, AKI had no influence on infarct size or neurologic function after experimental ischemic cerebral stroke.Item Open Access Neuroprotective efficacy from a lipophilic redox-modulating Mn(III) N-Hexylpyridylporphyrin, MnTnHex-2-PyP: rodent models of ischemic stroke and subarachnoid hemorrhage.(The Journal of pharmacology and experimental therapeutics, 2011-09) Sheng, Huaxin; Spasojevic, Ivan; Tse, Hubert M; Jung, Jin Yong; Hong, Jun; Zhang, Zhiquan; Piganelli, Jon D; Batinic-Haberle, Ines; Warner, David SIntracerebroventricular treatment with redox-regulating Mn(III) N-hexylpyridylporphyrin (MnPorphyrin) is remarkably efficacious in experimental central nervous system (CNS) injury. Clinical development has been arrested because of poor blood-brain barrier penetration. Mn(III) meso-tetrakis (N-hexylpyridinium-2-yl) porphyrin (MnTnHex-2-PyP) was synthesized to include four six-carbon (hexyl) side chains on the core MnPorphyrin structure. This has been shown to increase in vitro lipophilicity 13,500-fold relative to the hydrophilic ethyl analog Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP). In normal mice, we found brain MnTnHex-2-PyP accumulation to be ∼9-fold greater than MnTE-2-PyP 24 h after a single intraperitoneal dose. We then evaluated MnTnHex-2-PyP efficacy in outcome-oriented models of focal cerebral ischemia and subarachnoid hemorrhage. For focal ischemia, rats underwent 90-min middle cerebral artery occlusion. Parenteral MnTnHex-2-PyP treatment began 5 min or 6 h after reperfusion onset and continued for 7 days. Neurologic function was improved with both early (P = 0.002) and delayed (P = 0.002) treatment onset. Total infarct size was decreased with both early (P = 0.03) and delayed (P = 0.01) treatment. MnTnHex-2-PyP attenuated nuclear factor κB nuclear DNA binding activity and suppressed tumor necrosis factor-α and interleukin-6 expression. For subarachnoid hemorrhage, mice underwent perforation of the anterior cerebral artery and were treated with intraperitoneal MnTnHex-2-PyP or vehicle for 3 days. Neurologic function was improved (P = 0.02), and vasoconstriction of the anterior cerebral (P = 0.0005), middle cerebral (P = 0.003), and internal carotid (P = 0.015) arteries was decreased by MnTnHex-2-PyP. Side-chain elongation preserved MnPorphyrin redox activity, but improved CNS bioavailability sufficient to cause improved outcome from acute CNS injury, despite delay in parenteral treatment onset of up to 6 h. This advance now allows consideration of MnPorphyrins for treatment of cerebrovascular disease.Item Open Access Transcription factor Nrf2 hyperactivation in early-phase renal ischemia-reperfusion injury prevents tubular damage progression.(Kidney international, 2017-02) Nezu, Masahiro; Souma, Tomokazu; Yu, Lei; Suzuki, Takafumi; Saigusa, Daisuke; Ito, Sadayoshi; Suzuki, Norio; Yamamoto, MasayukiAcute kidney injury is a devastating disease with high morbidity in hospitalized patients and contributes to the pathogenesis of chronic kidney disease. An underlying mechanism of acute kidney injury involves ischemia-reperfusion injury which, in turn, induces oxidative stress and provokes organ damage. Nrf2 is a master transcription factor that regulates the cellular response to oxidative stress. Here, we examined the role of Nrf2 in the progression of ischemia-reperfusion injury-induced kidney damage in mice using genetic and pharmacological approaches. Both global and tubular-specific Nrf2 activation enhanced gene expression of antioxidant and NADPH synthesis enzymes, including glucose-6-phosphate dehydrogenase, and ameliorated both the initiation of injury in the outer medulla and the progression of tubular damage in the cortex. Myeloid-specific Nrf2 activation was ineffective. Short-term administration of the Nrf2 inducer CDDO during the initial phase of injury ameliorated the late phase of tubular damage. This inducer effectively protected the human proximal tubular cell line HK-2 from oxidative stress-mediated cell death while glucose-6-phosphate dehydrogenase knockdown increased intracellular reactive oxygen species. These findings demonstrate that tubular hyperactivation of Nrf2 in the initial phase of injury prevents the progression of reactive oxygen species-mediated tubular damage by inducing antioxidant enzymes and NADPH synthesis. Thus, Nrf2 may be a promising therapeutic target for preventing acute kidney injury to chronic kidney disease transition.Item Open Access Ubc9 overexpression and SUMO1 deficiency blunt inflammation after intestinal ischemia/reperfusion.(Laboratory investigation; a journal of technical methods and pathology, 2018-06) Karhausen, Jörn; Bernstock, Joshua D; Johnson, Kory R; Sheng, Huaxin; Ma, Qing; Shen, Yuntian; Yang, Wei; Hallenbeck, John M; Paschen, WulfThe intestinal epithelium constitutes a crucial defense to the potentially life-threatening effects of gut microbiota. However, due to a complex underlying vasculature, hypoperfusion and resultant tissue ischemia pose a particular risk to function and integrity of the epithelium. The small ubiquitin-like modifier (SUMO) conjugation pathway critically regulates adaptive responses to metabolic stress and is of particular significance in the gut, as inducible knockout of the SUMO-conjugating enzyme Ubc9 results in rapid intestinal epithelial disintegration. Here we analyzed the pattern of individual SUMO isoforms in intestinal epithelium and investigated their roles in intestinal ischemia/reperfusion (I/R) damage. Immunostaining revealed that epithelial SUMO2/3 expression was almost exclusively limited to crypt epithelial nuclei in unchallenged mice. However, intestinal I/R or overexpression of Ubc9 caused a remarkable enhancement of epithelial SUMO2/3 staining along the crypt-villus axis. Unexpectedly, a similar pattern was found in SUMO1 knockout mice. Ubc9 transgenic mice, but also SUMO1 knockout mice were protected from I/R injury as evidenced by better preserved barrier function and blunted inflammatory responses. PCR array analysis of microdissected villus-tip epithelia revealed a specific epithelial contribution to reduced inflammatory responses in Ubc9 transgenic mice, as key chemotactic signaling molecules such as IL17A were significantly downregulated. Together, our data indicate a critical role particularly of the SUMO2/3 isoforms in modulating responses to I/R and provide the first evidence that SUMO1 deletion activates a compensatory process that protects from ischemic damage.