Abstract 061: Interstitial Matrix Flow-Regulation:Myocardial Fibroblasts Respond to Colloidosmotic Pressure

Ischemia-reperfusion injury induces large differences in hydration potential between ischemic and nonischemic areas of the myocardium. They influence the rate and volume of fluid transfer in myocardial explants; temperature-dependent hydration-potential differences of approximately 100 mmHg in at-risk areas, as opposed to contiguous areas that are not at risk, suggest prompt interstitial fluid-transfer control mechanisms (Circ. Res . 2012;11:A235) . Aim: We adapted osmotic-stress techniques to determine whether myocardial fibroblasts, which are known to respond to mechanical and flow signals, also respond to hydration-potential changes. Methods: Fibroblasts were isolated from midwall regions of the left ventricles of healthy pigs using standard procedures. They were incorporated into 3-dimensional collagen gels of 500 mm 3 volume at 150 cells/mm 3 and equilibrated overnight in cultures using the nontoxic, inert polymer polyethylene glycol 8000 (molecular radius ~26.5 Å; concentration range 0-10% w/w) to adjust colloidosmotic pressure from approximately 5 to 205 mmHg . After the gels were detached from the dish, fluid flux was derived from any time-dependent changes in their dimensions. Results: The volume of gels without fibroblasts did not change significantly at any coloidosmotic pressure. In those with fibroblasts, the volume decreased, more slowly in those subjected to higher-than-plasma pressure levels. Progression curves conformed well to a two-exponential term model (R 2 >0.9) suggesting that two parallel processes contribute to matrix efflux, one relatively fast, with decay constant 0.274 ± 0.014 (n = 3) , and another ~50-fold slower. Initial rates were calculated from the fitted curves, and linear regression analysis used to examine their dependence on colloidosmotic pressure. Initial efflux rates decreased with pressure, mean slope, - 0.29 ± 0.08 µl/h/mmHg (R 2 = 0.7; P-value = 0.006). Conclusion: In vitro , fibroblasts in collagen matrices regulate fluid efflux in response to colloidosmotic stresses within the range of hydration-potential differences measured in myocardial explants after ischemia-reperfusion injury.

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Effects of Endotoxin on Neutrophil-Mediated Ischemia/Reperfusion Injury in the Rat Heart In Vivo

Experimental Biology and Medicine ◽

10.1177/153537020122600409 ◽

2001 ◽

Vol 226 (4) ◽

pp. 320-327 ◽

Cited By ~ 8

Author(s):

Brian P. Lipton ◽

Joseph B. Delcarpio ◽

Kathleen H. McDonough

Keyword(s):

At Risk ◽

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Isolated Heart ◽

Ischemia Reperfusion ◽

Left Ventricular ◽

Necrotic Area ◽

Area At Risk

We have previously shown that a nonlethal dose of lipopolysaccharide (LPS) decreases L-selectin expression of neutrophils (PMNs), thereby preventing PMN-mediated reperfusion injury in the isolated heart. In the present study we determined whether or not that dose of LPS would protect hearts during in vivo ischemia and reperfusion by preventing PMN-induced reperfusion injury. Rats receiving saline vehicle showed marked myocardial injury (necrotic area/area at risk = 82% ± 2%) and significant depression in left ventricular function as assessed in the isolated isovolumic heart preparation at constant flow rates of 5, 10, 15, and 20 ml/min. The administration of LPS (100 μg/kg body wt) 7 hr prior to ischemia resulted in a reduction in myocardial damage (necrotic area/area at risk = 42% ± 3%) and preservation of function. Myocardial function was similar to that of sham ischemic saline- and LPS-treated rats. Moreover, PMN infiltration as determined by histology was quantitatively more severe in hearts of saline-treated rats than in hearts of LPS-treated rats. Isolated hearts from vehicle- and LPS-treated animals undergoing sham ischemia in vivo recovered to the same extent after in vitro ischemia/reperfusion, suggesting that LPS did not induce protection by altering intrinsic properties of the heart. Our results indicate that LPS-induced protection of the heart from in vivo PMN-mediated ischemia/reperfusion injury may be due to decreased L-selectin expression of PMNs in LPS-treated animals.

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N6-methyladenosine demethylase FTO impairs hepatic ischemia–reperfusion injury via inhibiting Drp1-mediated mitochondrial fragmentation

Cell Death and Disease ◽

10.1038/s41419-021-03622-x ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Ying Dong Du ◽

Wen Yuan Guo ◽

Cong Hui Han ◽

Ying Wang ◽

Xiao Song Chen ◽

...

Keyword(s):

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Mitochondrial Fragmentation ◽

Hepatic Ischemia ◽

Adeno Associated Virus ◽

Downstream Target ◽

Hepatic Ischemia Reperfusion

AbstractDespite N6-methyladenosine (m6A) is functionally important in various biological processes, its role and the underlying regulatory mechanism in the liver remain largely unexplored. In the present study, we showed that fat mass and obesity-associated protein (FTO, an m6A demethylase) was involved in mitochondrial function during hepatic ischemia–reperfusion injury (HIRI). We found that the expression of m6A demethylase FTO was decreased during HIRI. In contrast, the level of m6A methylated RNA was enhanced. Adeno-associated virus-mediated liver-specific overexpression of FTO (AAV8-TBG-FTO) ameliorated the HIRI, repressed the elevated level of m6A methylated RNA, and alleviated liver oxidative stress and mitochondrial fragmentation in vivo and in vitro. Moreover, dynamin-related protein 1 (Drp1) was a downstream target of FTO in the progression of HIRI. FTO contributed to the hepatic protective effect via demethylating the mRNA of Drp1 and impairing the Drp1-mediated mitochondrial fragmentation. Collectively, our findings demonstrated the functional importance of FTO-dependent hepatic m6A methylation during HIRI and provided valuable insights into the therapeutic mechanisms of FTO.

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The Sodium-Glucose Cotransporter-2 Inhibitor Canagliflozin Alleviates Endothelial Dysfunction Following In Vitro Vascular Ischemia/Reperfusion Injury in Rats

International Journal of Molecular Sciences ◽

10.3390/ijms22157774 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7774

Author(s):

Sevil Korkmaz-Icöz ◽

Cenk Kocer ◽

Alex A. Sayour ◽

Patricia Kraft ◽

Mona I. Benker ◽

...

Keyword(s):

Endothelial Dysfunction ◽

Reperfusion Injury ◽

Vascular Function ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Artery Bypass ◽

Diabetic Rats ◽

Organ Bath ◽

Sodium Glucose Cotransporter

Vascular ischemia/reperfusion injury (IRI) contributes to graft failure and adverse clinical outcomes following coronary artery bypass grafting. Sodium-glucose-cotransporter (SGLT)-2-inhibitors have been shown to protect against myocardial IRI, irrespective of diabetes. We hypothesized that adding canagliflozin (CANA) (an SGLT-2-inhibitor) to saline protects vascular grafts from IRI. Aortic rings from non-diabetic rats were isolated and immediately mounted in organ bath chambers (control, n = 9–10 rats) or underwent cold ischemic preservation in saline, supplemented either with a DMSO vehicle (IR, n = 8–10 rats) or 50µM CANA (IR + CANA, n = 9–11 rats). Vascular function was measured, the expression of 88 genes using PCR-array was analyzed, and feature selection using machine learning was applied. Impaired maximal vasorelaxation to acetylcholine in the IR-group compared to controls was significantly ameliorated by CANA (IR 31.7 ± 3.2% vs. IR + CANA 51.9 ± 2.5%, p < 0.05). IR altered the expression of 17 genes. Ccl2, Ccl3, Ccl4, CxCr4, Fos, Icam1, Il10, Il1a and Il1b have been found to have the highest interaction. Compared to controls, IR significantly upregulated the mRNA expressions of Il1a and Il6, which were reduced by 1.5- and 1.75-fold with CANA, respectively. CANA significantly prevented the upregulation of Cd40, downregulated NoxO1 gene expression, decreased ICAM-1 and nitrotyrosine, and increased PECAM-1 immunoreactivity. CANA alleviates endothelial dysfunction following IRI.

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Overexpression of SP1 restores autophagy to alleviate acute renal injury induced by ischemia-reperfusion through the miR-205/PTEN/Akt pathway

Journal of Inflammation ◽

10.1186/s12950-021-00270-y ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Chong Huang ◽

Yan Chen ◽

Bin Lai ◽

Yan-Xia Chen ◽

Cheng-Yun Xu ◽

...

Keyword(s):

Reperfusion Injury ◽

Cell Apoptosis ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Renal Ischemia ◽

Akt Pathway ◽

Acute Renal Injury ◽

Injury Model ◽

Renal Ischemia Reperfusion Injury

Abstract Background Acute kidney injury (AKI) is a major kidney disease with poor clinical outcome. SP1, a well-known transcription factor, plays a critical role in AKI and subsequent kidney repair through the regulation of various cell biologic processes. However, the underlying mechanism of SP1 in these pathological processes remain largely unknown. Methods An in vitro HK-2 cells with anoxia-reoxygenation injury model (In vitro simulated ischemic injury disease) and an in vivo rat renal ischemia-reperfusion injury model were used in this study. The expression levels of SP1, miR-205 and PTEN were detected by RT-qPCR, and the protein expression levels of SP1, p62, PTEN, AKT, p-AKT, LC3II, LC3I and Beclin-1 were assayed by western blot. Cell proliferation was assessed by MTT assay, and the cell apoptosis was detected by flow cytometry. The secretions of IL-6 and TNF-α were detected by ELISA. The targeted relationship between miR-205 and PTEN was confirmed by dual luciferase report assay. The expression and positioning of LC-3 were observed by immunofluorescence staining. TUNEL staining was used to detect cell apoptosis and immunohistochemical analysis was used to evaluate the expression of SP1 in renal tissue after ischemia-reperfusion injury in rats. Results The expression of PTEN was upregulated while SP1 and miR-205 were downregulated in renal ischemia-reperfusion injury. Overexpression of SP1 protected renal tubule cell against injury induced by ischemia-reperfusion via miR-205/PTEN/Akt pathway mediated autophagy. Overexpression of SP1 attenuated renal ischemia-reperfusion injury in rats. Conclusions SP1 overexpression restored autophagy to alleviate acute renal injury induced by ischemia-reperfusion through the miR-205/PTEN/Akt pathway.

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In vivo and In vitro PPAR-y Activation Decreases M1-Macrophage Polarization and Improves Liver Ischemia Reperfusion Injury

Transplantation Journal ◽

10.1097/01.tp.0000543674.85457.9b ◽

2018 ◽

Vol 102 ◽

pp. S708

Author(s):

Ivan Linares ◽

Agata Bartczak ◽

Kaveh Farrokhi ◽

Dagmar Kollmann ◽

Moritz Kaths ◽

...

Keyword(s):

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Macrophage Polarization ◽

Liver Ischemia ◽

M1 Macrophage

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Poly-IC Preconditioning Protects against Cerebral and Renal Ischemia-Reperfusion Injury

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2011.160 ◽

2011 ◽

Vol 32 (2) ◽

pp. 242-247 ◽

Cited By ~ 29

Author(s):

Amy E B Packard ◽

Jason C Hedges ◽

Frances R Bahjat ◽

Susan L Stevens ◽

Michael J Conlin ◽

...

Keyword(s):

Reperfusion Injury ◽

Inflammatory Responses ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Renal Ischemia ◽

Cortical Cells ◽

Polycytidylic Acid ◽

Populations At Risk

Preconditioning induces ischemic tolerance, which confers robust protection against ischemic damage. We show marked protection with polyinosinic polycytidylic acid (poly-IC) preconditioning in three models of murine ischemia-reperfusion injury. Poly-IC preconditioning induced protection against ischemia modeled in vitro in brain cortical cells and in vivo in models of brain ischemia and renal ischemia. Further, unlike other Toll-like receptor (TLR) ligands, which generally induce significant inflammatory responses, poly-IC elicits only modest systemic inflammation. Results show that poly-IC is a new powerful prophylactic treatment that offers promise as a clinical therapeutic strategy to minimize damage in patient populations at risk of ischemic injury.

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Abstract 235: Ischemia-Reperfusion Injury Decreases Myocardial Hydration Potential Without Changing Flow Resistance in the Interstitial Matrix

Circulation Research ◽

10.1161/res.111.suppl_1.a235 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Maria P McGee ◽

Michael Morykwas ◽

James Jordan ◽

Louis Argenta

Keyword(s):

At Risk ◽

Flow Resistance ◽

Ischemia Reperfusion Injury ◽

Ex Vivo ◽

Ischemia Reperfusion ◽

P Value ◽

Mechanical Forces ◽

Interstitial Flow ◽

Elastic Recoil ◽

Fluid Accumulation

Interstitial edema is an early response to myocardial ischemia, leading to fibrosis and remodeling in several heart failure conditions. We aimed to clarify whether osmotic, frictional, or mechanical forces drive fluid accumulation. Equilibrium and dynamic interstitial hydration parameters were determined, compared, and analyzed using osmotic stress approaches in explants from ischemic and nonischemic myocardial regions of pig heart. They were isolated after injury induced by ligating 3-4 branches of the left anterior descending coronary artery, for 85 min followed by 3 hours’ reperfusion. Their volume changed (Δ V max ) linearly with colloidosmotic pressure in both ischemic and nonischemic areas, yielding interstitial compliance values of 1.04 ± 0.09 and 1.08 ± 0.05 µl/g/ mmHg , which do not differ significantly, and hydration potentials from the abscissa intercepts at Δ V max = 0, of -121.4 ± 28 and -14.7 ± 7.6 mmHg, which do (mean ± SE, n = 5 , P-value = 0.001). These hydration potential differences manifest ex-vivo influx rates 8.5 ± 2.7- fold slower in ischemic than nonischemic myocardium. Surprisingly, interstitial flow resistance values derived from net-flow rates at an imposed pressure difference of 216 mmHg were 0.23 ± 0.08 and 0.19 ± 0.01 µl -1 . g. min and did not differ significantly between the areas. The similarity in interstitial compliance and fluid resistance indicates that the more negative hydration potential and faster efflux rates in at-risk regions after reperfusion are due to increased hydrostatic pressure rather than decreased osmotic or frictional forces. Tissue distends due to interstitial fluid accumulation against matrix mechanical forces, including elastic recoil of the collagen elastin mesh and fibroblast action, consistent with impaired drainage and persistent diastolic-like conditions during reperfusion of at-risk areas in vivo . These results indicate changes in pressure gradient magnitude and may have clinical and therapeutic implications; for example, reversal of paracrine interstitial flows during early remodeling

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Abstract 193: Antithrombin Perfluorocarbon Nanoparticles Ameliorate Renal Injury Following Transient Warm Ischemia

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.34.suppl_1.193 ◽

2014 ◽

Vol 34 (suppl_1) ◽

Author(s):

Chandu Vemuri ◽

Junjie Chen ◽

Rohun U Palekar ◽

John S Allen ◽

Xiaoxia Yang ◽

...

Keyword(s):

Reperfusion Injury ◽

Renal Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Kidney Injury ◽

Warm Ischemia ◽

P Value ◽

Sprague Dawley ◽

Histologic Analysis ◽

Microvascular Thrombosis

Objective: Thrombin mediated microvascular thrombosis plays a crucial role in the pathogenesis of acute renal reperfusion injury following transient ischemia. We hypothesize that anti-thrombin nanoparticles will ameliorate acute renal injury by inhibiting microvascular thrombosis. Methods: Adult, male Sprague Dawley rats were randomized into two groups of 5 to receive tail vein injections of saline or nanoparticles loaded with Phe[D]-Pro-Arg-Chloromethylketone (NP-PPACK). Immediately following injection, all animals underwent operative bilateral renal artery occlusion to create 45 minutes of warm ischemia, followed by restoration of renal blood flow. Blood samples were drawn daily and animals were euthanized on day 1 or 7 for histologic analysis of kidney injury (H&E, TUNEL and thrombin staining). Results: Histologic analysis of renal tissue revealed significant apoptosis, necrosis and thrombin accumulation 1 day after ischemia-reperfusion, confirming acute kidney injury. The peak creatinine (mg/dl) on day 1 was significantly lower in NP-PPACK treated animals (0.57 +/- 0.07 (SEM)) than in saline treated controls (1.40 +/- 0.20 (SEM); p-value <0.01). Furthermore, animals treated with NP-PPACK continued to exhibit less renal dysfunction for 7 days after injury (Figure 1). Conclusion: Histologically confirmed intrarenal thrombosis was detected one day after ischemia-reperfusion injury. Targeted inhibition of thrombin with NP-PPACK prevented a decline in renal function following transient occlusion. Future work will focus on defining the underlying mechanisms of this effect.

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