Abstract 212: Cd4+ T-cell Activation By T-cell Receptor Engagement Contributes To Myocardial Ischemia-reperfusion Injury

Background: We have recently shown that CD4 + but not CD8 + T-cells contribute to ischemia-reperfusion injury of the myocardium. We therefore hypothesized that CD4 + T-cells become activated by autoantigen recognition via their T-cell receptor during reperfusion. Methods and Results: Infarct size as percent of the area-at-risk was determined by combined Evans` blue and triphenyltetrazolium (TTC) staining after 30 minutes of in vivo ischemia followed by 24 hours reperfusion in mice. After 24 hours of reperfusion there was a significantly increased population of CD4 + T-cells which expressed the surface protein CD40L in comparison to sham operated mice [n≥7; p<0.05; WT 10.8 ± 0.2% vs. sham 6.4 ± 0.5%]. CD40L is typically expressed in T-cells activated by T-cell receptor engagement. OT-II mice carry a transgenic T-cell receptor with specificity for an ovalbumin-derived peptide. These mice have a limited T-cell receptor repertoire, dominated by specificity for the irrelevant antigen ovalbumin. After 30 minutes of ischemia and 24 hours of reperfusion OT-II mice showed significantly reduction in infarct size [n≥4; p= 0.02; infarct/area at risk: OTII mice 38.9 ± 2.4% vs. WT mice 63.7 ± 6.6 % ]. Administration of a CD40L blocking antibody to wildtype mice also reduced infarct size when compared to administration of isotype-matched antibodies [n≥6; p = 0.03; infarct/ area at risk: anti-CD154 treatment 60.4 ± 3.4% vs. control 75.3 ± 4.1%]. CD4 + CD25 + Foxp3 + T-cells (natural T-regulatory cells) have a low activation threshold and constitute a T-cell subset with reactivity against autoantigens. Depletion of these cells by diphtheria-toxin application in a mouse model expressing the diphtheria-toxin receptor under the Foxp3 promotor also resulted in a significant reduction of infarct size when compared to diphtheria-toxin treated wildtype mice [n≥4; p=0.03; infarct/ area at risk: T reg -depleted DEREG mice 51.9± 3% vs. WT littermates 72.3± 2%]. Conclusion: Our results indicate that CD4 + T-cells that have been activated by an MHC class II/ T-cell receptor dependent mechanism, presumably by autoantigen recognition, contribute to myocardial ischemia-reperfusion injury.

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A Unique Population of Regulatory T Cells in Heart Potentiates Cardiac Protection From Myocardial Infarction

Circulation ◽

10.1161/circulationaha.120.046789 ◽

2020 ◽

Vol 142 (20) ◽

pp. 1956-1973

Author(s):

Ni Xia ◽

Yuzhi Lu ◽

Muyang Gu ◽

Nana Li ◽

Meilin Liu ◽

...

Keyword(s):

Myocardial Infarction ◽

T Cells ◽

T Cell ◽

Reperfusion Injury ◽

T Cell Receptor ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Cell Receptor ◽

Interleukin 33 ◽

Injured Myocardium

Background: Regulatory T cells (Tregs), traditionally recognized as potent suppressors of immune response, are increasingly attracting attention because of a second major function: residing in parenchymal tissues and maintaining local homeostasis. However, the existence, unique phenotype, and function of so-called tissue Tregs in the heart remain unclear. Methods: In mouse models of myocardial infarction (MI), myocardial ischemia/reperfusion injury, or cardiac cryoinjury, the dynamic accumulation of Tregs in the injured myocardium was monitored. The bulk RNA sequencing was performed to analyze the transcriptomic characteristics of Tregs from the injured myocardium after MI or ischemia/reperfusion injury. Photoconversion, parabiosis, single-cell T-cell receptor sequencing, and adoptive transfer were applied to determine the source of heart Tregs. The involvement of the interleukin-33/suppression of tumorigenicity 2 axis and Sparc (secreted acidic cysteine-rich glycoprotein), a molecule upregulated in heart Tregs, was further evaluated in functional assays. Results: We showed that Tregs were highly enriched in the myocardium of MI, ischemia/reperfusion injury, and cryoinjury mice. Transcriptomic data revealed that Tregs isolated from the injured hearts had plenty of differentially expressed transcripts in comparison with their lymphoid counterparts, including heart-draining lymphoid nodes, with a phenotype of promoting infarct repair, indicating a unique characteristic. The heart Tregs were accumulated mainly because of recruitment from the circulating Treg pool, whereas local proliferation also contributed to their expansion. Moreover, a remarkable case of repeatedly detected T-cell receptor of heart Tregs, more than that of spleen Tregs, suggests a model of clonal expansion. Besides, Helios high Nrp-1 high phenotype proved the mainly thymic origin of heart Tregs, with a small contribution of phenotypic conversion of conventional CD4 + T cells, proved by the analysis of T-cell receptor repertoires and conventional CD4 + T cells adoptive transfer experiments. The interleukin-33/suppression of tumorigenicity 2 axis was essential for sustaining heart Treg populations. Last, we demonstrated that Sparc, which was highly expressed by heart Tregs, acted as a critical factor to protect the heart against MI by increasing collagen content and boosting maturation in the infarct zone. Conclusions: We identified and characterized a phenotypically and functionally unique population of heart Tregs that may lay the foundation to harness Tregs for cardioprotection in MI and other cardiac diseases.

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Deletion of the Semaphorin, Sema4D, but Not Inhibition of Sema4D Shedding by ADAM17, Impairs Platelet Function and Reduces Infarct Size After Myocardial Ischemia.

Blood ◽

10.1182/blood.v114.22.771.771 ◽

2009 ◽

Vol 114 (22) ◽

pp. 771-771

Author(s):

Li Zhu ◽

Tao Wang ◽

Hong Jiang ◽

Timothy J. Stalker ◽

Karen P. Fong ◽

...

Keyword(s):

At Risk ◽

T Cells ◽

Endothelial Cells ◽

Reperfusion Injury ◽

Platelet Function ◽

Ischemia Reperfusion Injury ◽

Fetal Liver ◽

Ischemia Reperfusion ◽

Area At Risk ◽

Fetal Liver Cells

Abstract Abstract 771 Introduction. Platelets are activated early during the reperfusion of ischemic myocardium, potentially exacerbating the extent of ischemia/reperfusion (I/R) injury. We have recently shown (Zhu, et al., PNAS 2007) that platelets express the semaphorin family member, sema4D, as do T-cells. Sema4D is a cell surface protein whose receptors are expressed by B-cells, monocytes and endothelial cells as well as platelets. Loss of sema4D expression in mice causes a defect in signaling downstream of the platelet collagen receptor, glycoprotein (GP) VI, inhibiting platelet function in vitro and in vivo, and reducing the extent of platelet hyperresponsiveness and atherothrombosis in the setting of dyslipidemia (Zhu, et al. ATVB 2009). Because of the role played by platelets, leukocytes and endothelial cells in reperfusion injury, here we asked whether loss of sema4D expression can also protect the heart, reducing the extent of damage following temporary ischemia. Methods. The left anterior descending coronary artery of anaesthetized mice was ligated for 45 min. After reperfusion for 48 hours, the mice were re-anesthetized and perfused with 2,3,5-triphenyltetrazolium chloride to measure the area of infarction. Fluorescent microspheres were used to delineate the area at risk. Comparisons were made between sema4D(−/−) and wild type mice produced by breeding sema4D(+/−) heterozygotes. Results. Although there was no difference between the sema4D(−/−) and WT mice with respect to either heart size or area at risk, we observed a substantial (57%) decrease in infarct size in the sema4D(−/−) mice expressed as a fraction of the area at risk (N=7-9, p<0.005). Since sema4D is shed from the surface of activated platelets and T-cells by the metalloprotease, ADAM17, producing a large bioactive fragment, we next asked whether the protection against ischemia/reperfusion injury conferred by the sema4D knockout is due to the loss of cell-associated or soluble sema4D. Chimeric mice were produced in which hematopoiesis was reconstituted in irradiated sema4D(+/+) mice using fetal liver cells from mouse embryos that lack functional ADAM17. This produces mice in which sema4D is expressed as usual in the hematopoietic lineages, but unable to be shed. Chimerism, inhibition of sema4D shedding and recovery of normal cell counts were confirmed after transplantation. The ischemia/reperfusion studies were repeated comparing chimeras reconstituted with ADAM17-deficient and ADAM17-replete fetal liver cells. In contrast to the sema4D knockout, the extent of infarction was the same whether or not ADAM17 was functional and sema4D was shed. Conclusions. Although the role of sema4D and its receptors have been studied most extensively in the context of T-cell interactions with B-cells, our previous studies have made a case for the involvement of sema4D in platelet:platelet and platelet:endothelial cell interactions. We now show for the first time that 1) loss of sema4D expression in mice confers protection against ischemia/reperfusion injury in the myocardium, and 2) preventing the formation of soluble, bioactive sema4D is insufficient to recapitulate this effect. Since sema4D and its receptors are expressed on more than just platelets, it cannot be concluded that the observed protection in the knockout is solely due to the absence of platelet sema4D. However, experience with other knockouts that reduce platelet function suggests that the defects that we have observed in sema4D(−/−) platelet function are likely to contribute. Regardless of whether expression on platelets is entirely or only partly responsible for the observed phenotype, sema4D is an interesting target for therapeutic intervention. Disclosures: No relevant conflicts of interest to declare.

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Role of the T-cell receptor in kidney ischemia–reperfusion injury

Kidney International ◽

10.1038/sj.ki.5000038 ◽

2006 ◽

Vol 69 (2) ◽

pp. 233-238 ◽

Cited By ~ 66

Author(s):

V. Savransky ◽

R.R. Molls ◽

M. Burne-Taney ◽

C.-C. Chien ◽

L. Racusen ◽

...

Keyword(s):

T Cell ◽

Reperfusion Injury ◽

T Cell Receptor ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Cell Receptor ◽

Kidney Ischemia

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Abstract 714: Targeting Coagulation Factor XII to Protect from Cardiac Ischemia Reperfusion Injury

Circulation ◽

10.1161/circ.116.suppl_16.ii_134-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Stefan Frantz ◽

Johann Bauersachs ◽

Anna Adamek ◽

Nadja Blomer ◽

Georg Ertl ◽

...

Keyword(s):

At Risk ◽

Myocardial Ischemia ◽

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Factor Xii ◽

Area At Risk ◽

Infarct Area ◽

Myocardial Ischemia Reperfusion Injury ◽

Myocardial Ischemia Reperfusion

Formation of fibrin is critical for limiting blood loss at a site of blood vessel injury (hemostasis), but may also contribute to vascular thrombosis and thus exaggerate myocardial ischemia/reperfusion injury. Hereditary deficiency of factor XII (FXII), the protease that triggers the intrinsic pathway of coagulation in vitro, is not associated with spontaneous or excessive injury-related bleeding, but can reduce thrombus formation. Therefore, we studied the contribution of FXII for myocardial ischemia reperfusion injury. Following 30 minutes of ischemia and 24 hours of reperfusion infarct size in FXII deficient mice was significantly reduced as compared to wild type controls (infarct/area at risk, WT vs. FXII−/−, 73.5%±4.4% vs. 42.3±1.6%, p<0.001) despite similar area at risk (WT vs. FXII−/−, 28.3%±1.7% vs. 29.9±1.0%, p=n.s.). There was no difference in bleeding complications and bleeding time. Mice deficient in the FXII substrate factor XI were similarly protected from ischemia reperfusion injury (infarct/area at risk, FXI−/−, 16.9%±4.1%, vs. WT p<0.001). The phenotype of FXII−/−mice could be rescued by intravenous application of human FXII (infarct/area at risk, FXII−/−+FXII, 77.3%±8.4%, p<0.001 vs. FXIIKO). WT mice treated with the FXII inhibitor PCK (Pro-Phe-Arg-chloromethylketone) were similarly protected from myocardial ischemia/reperfusion injury (infarct/area at risk, 46.5% ±3.7%, vs. WT p<0.001). The data suggest that the intrinsic pathway is crucial for pathological clotting in myocardial ischemia reperfusion injury. FXII inhibition may offer a selective and safe strategy to reduce ischemic injury.

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Inhibition of Type 2 Sodium-Glucose Transporters and Na+/H+ Exchanger-1 produces similar cardioprotective effects in response to ischemiareperfusion injury

Proceedings of IMPRS ◽

10.18060/23423 ◽

2019 ◽

Vol 2 (1) ◽

Author(s):

Bianca S. Blaettner ◽

Hana E. Baker ◽

Adam G. Goodwill ◽

Hannah E. Clark ◽

Michael C. Kozlowski ◽

...

Keyword(s):

At Risk ◽

Infarct Size ◽

Reperfusion Injury ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Glucose Transporters ◽

Left Ventricular ◽

Area At Risk ◽

Cardioprotective Effects

Background and Hypothesis: Recent studies indicate that inhibition of Type 2 Sodium-Glucose Transporters (SGLT2i) augments diastolic filling volume and mitigates myocardial ischemic injury. This study tested the hypothesis that inhibition of the Na+/H+ Exchanger-1 (NHE-1) mimics the cardioprotective effects of SGLT2i in response to ischemia-reperfusion injury. Experimental Design or Project Methods: Lean swine (~50 kg) were anesthetized, a thoracotomy performed, and perivascular flow transducers placed around the left anterior descending (LAD) and circumflex coronary (LCX) arteries. A pressure-volume (PV) catheter was then inserted into the left ventricle. Swine received a 15 min infusion of vehicle (DMSO; n = 3), the SGLT2i Canagliflozin (30 µM; n = 3), or the NHE-1 inhibitor Cariporide (1µM; n = 3) prior to a 60 min total occlusion of the LCX and 2-hour reperfusion period. Following reperfusion, the LCX was re-occluded and a 2.5% Patent Blue 5 solution was administered to identify area at risk. The heart was excised, sectioned, and incubated in a 2,3,5-triphenyltetrazolium chloride (TTC) solution. Images were collected and analyzed for area at risk and infarct size. Results: In the vehicle treated group, 2 of the 3 swine studied died prematurely before the completion of the protocol; one at baseline and one during ischemia. Our initial findings support that left ventricular end diastolic volume increases in response to regional myocardial ischemia in swine that received either Canagliflozin or Cariporide. This increase in diastolic volume was associated with an increase in stroke volume (i.e. Frank-Starling effect) and a reduction in myocardial infarct size in both treatment groups. Blood pressure tended to decrease to a similar extent in all groups. Conclusion and Potential Impact: These pilot studies suggest that inhibition of SGLT2 and NHE-1 produces similar functional and protective effects in response to regional ischemia-reperfusion injury. Further experiments are needed to corroborate these findings and examine the extent to which SGLT2i directly modulates NHE-1 activity.

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