Carmen Barthuber

The fibrin-derived peptide Bβ15- 42 is cardioprotective in a pig model of myocardial ischemia-reperfusion injury

Objective:The fibrin-derived peptide B&bgr;15–42 has been shown to reduce infarct size in rodent models of ischemia-reperfusion injury. To increase its potential for translation into the clinic, we studied the effects of B&bgr;15–42 in pigs, whose coronary anatomy is similar to that of humans. In addition, we evaluated the pharmacokinetics and safety of B&bgr;15–42 in several species, including humans. Design:Animal study and phase I trial. Setting:University hospital and contract research laboratories. Subjects:Pigs/healthy volunteers. Interventions:Male farm-bred Landrace pigs were subjected to 1 hr of left anterior descending coronary artery occlusion followed by 3 hrs of reperfusion. At the time of reperfusion, B&bgr;15–42 (2.4 mg/kg, n = 6) or random peptide (control; 2.4 mg/kg, n = 6) was administered as an intravenous bolus. As a positive control, pigs were subjected to ischemic preconditioning (n = 6). Cardiac damage and hemodynamics were recorded. Biodistribution and pharmacokinetics of B&bgr;15–42 were determined in rats and dogs. In a phase I trial involving 30 male healthy volunteers, pharmacokinetics and safety were tested in a randomized, double-blinded, placebo-controlled, parallel-group, single ascending dose study. Measurements and Main Results:B&bgr;15–42 and ischemic preconditioning significantly reduced myocardial infarct size and troponin I levels. B&bgr;15–42 also reduces interleukin-6 levels, underlining its anti-inflammatory properties. Furthermore, in humans, the pharmacokinetics of the peptide B&bgr;15–42 were comparable to those of animals, and no serious adverse effects were observed. Conclusions:B&bgr;15–42 elicits cardioprotection in pigs and is clinically safe in phase I testing of humans. This study confirms the new concept of a pathogenic role of fibrin derivatives in myocardial reperfusion injury, which can be inhibited by peptide B&bgr;15–42.

Cardioprotection by remote ischemic preconditioning exhibits a signaling pattern different from local ischemic preconditioning

Remote ischemic preconditioning (RIPC) and local ischemic preconditioning (IPC) protect the myocardium from subsequent ischemia/reperfusion (I/R) injury. In this study, the protective effects of early RIPC, IPC, and the combination of both (RIPC-IPC) were characterized. Furthermore, the hypothesis was tested that protein kinase C (PKC) and mitogen-activated protein kinases (MAPKs), important mediators of IPC, are activated in RIPC. Infarct size, serum troponin T, and creatine kinase levels were assessed after 4 × 5-min noninvasive RIPC, local IPC, or a combination of both and 35 min of regional ischemia and 120 min of reperfusion. Protein kinase C ϵ and the MAPKs extracellular signal-regulated MAPK (ERK), c-jun N-terminal kinase (JNK), and p38 MAPK were analyzed by Western blot analysis and activity assays in the myocardium and skeletal muscle immediately after the preconditioning protocol. Remote ischemic preconditioning, IPC, and RIPC-IPC significantly reduced myocardial infarct size (RIPC-I/R: 54% ± 15%; IPC-I/R: 33% ± 15%; RIPC-IPC-I/R: 33% ± 15%; P < 0.05 vs. I/R [76% ± 14%]) and troponin T release (RIPC-I/R: 15.4 ± 6.4 ng/mL; IPC-I/R: 10.9 ± 7.0 ng/mL; RIPC-IPC-I/R: 9.8 ± 5.6 ng/mL; P < 0.05 vs. I/R [27.1 ± 12.0 ng/mL]) after myocardial I/R. Ischemic preconditioning led to an activation of PKCϵ and ERK 1/2, whereas RIPC did not lead to a translocation of PKCϵ to the mitochondria or phosphorylation of the MAPKs ERK 1/2, JNK 1/2, and p38 MAPK. Remote ischemic preconditioning did not induce translocation of PKCϵ to the mitochondria or phosphorylation of MAPKs in the preconditioned muscle tissue. Remote ischemic preconditioning, IPC, and RIPC-IPC exert early protection against myocardial I/R injury. Remote ischemic preconditioning and local IPC exhibit different activation dynamics of signal transducers in the myocardium. The studied PKC-MAPK pathway is likely not involved in the protective effects of RIPC.ABBREVIATIONS-AAR-area at risk; CK-creatine kinase; ERK-extracellular signal-regulated MAPK; IPC-ischemic preconditioning; I/R-ischemia and reperfusion; JNK-c-jun N-terminal kinase; MAPK-mitogen-activated protein kinase; PKC-protein kinase C; RIPC-remote ischemic preconditioning

Oxidized ATP inhibits T‐cell‐mediated autoimmunity

T cells directed against self antigens play an important role in several autoimmune diseases. The available immunosuppressive compounds used to treat autoimmune diseases are limited, and often they have side effects that limit their application. T cells express ATP receptors, which could be new target molecules to treat autoimmune disease. Here we analyzed the effect of oxidized ATP (oxATP), an inhibitor of the ATP receptor P2rx7, in different murine models of T‐cell‐mediated autoimmune diseases. Treatment with oxATP inhibited proliferation and effector function of T cells. In the systems we used, oxATP did not obviously interfere with the innate immune response, but strongly reduced antigen‐specific T‐cell responses. This treatment ameliorated T‐cell‐mediated autoimmune type I diabetes and autoimmune encephalitis in mice. In conclusion, oxATP was found to strongly inhibit activated T cells and could thus be used to target T‐cell‐mediated autoimmune disease.

Therapeutic injection of parp inhibitor ino-1001 preserves cardiac function in porcine myocardial ischemia and reperfusion without reducing infarct size

Pharmacological protection from myocardial reperfusion injury, despite plenty of approaches, has still not been realized in humans. We studied the putative infarct size (IS)-sparing capacity of poly(ADP-ribose)polymerase inhibitor, INO-1001, and focused on cardiac functional recovery during reperfusion. Male farm-bred Landrace pigs were subjected to 1-h left anterior descending coronary artery occlusion followed by 3 h of reperfusion (control). Infarct size was determined by triphenyltetrazolium chloride/Evans blue staining. Plasma markers of myocardial injury (troponin T, creatine kinase, lactate dehydrogenase) were determined upon protocol completion. Cardiac function was continuously assessed via pulmonary and femoral artery catheters. INO-1001 (1 mg/kg) was administered upon reperfusion in the treatment group. As a positive control, untreated pigs were subjected to ischemic preconditioning (10-min left anterior descending coronary artery occlusion followed by 15-min reperfusion before the intervention). Ischemic preconditioning reduced myocardial damage reflected by a smaller IS and lower plasma markers of myocardial injury. INO-1001 did not reduce IS but significantly improved functional recovery (increased stroke volume, cardiac index, and mixed venous oxygen saturation) during reperfusion compared with vehicle-treated control and ischemic preconditioning. Although we could not confirm the IS-sparing capacities of poly(ADP-ribose)polymerase inhibitor, INO-1001, the drug holds the potential of hemodynamic improvement during reperfusion.

Reduced type I interferon production by dendritic cells and weakened antiviral immunity in patients with Wiskott-Aldrich syndrome protein deficiency.

Background Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency caused by absence of Wiskott-Aldrich syndrome protein (WASP) expression, resulting in defective function of many immune cell lineages and susceptibility to severe bacterial, viral, and fungal infections. Despite a significant proportion of patients with WAS having recurrent viral infections, surprisingly little is known about the effects of WASP deficiency on antiviral immunity. Objective We sought to evaluate the antiviral immune response in patients with WASP deficiency in vivo. Methods Viral clearance and associated immunopathology were measured after infection of WASP-deficient (WAS KO) mice with lymphocytic choriomeningitis virus (LCMV). Induction of antiviral CD8+ T-cell immunity and cytotoxicity was documented in WAS KO mice by means of temporal enumeration of total and antigen-specific T-cell numbers. Type I interferon (IFN-I) production was measured in serum in response to LCMV challenge and characterized in vivo by using IFN-I reporter mice crossed with WAS KO mice. Results WAS KO mice showed reduced viral clearance and enhanced immunopathology during LCMV infection. This was attributed to both an intrinsic CD8+ T-cell defect and defective priming of CD8+ T cells by dendritic cells (DCs). IFN-I production by WAS KO DCs was reduced both in vivo and in vitro. Conclusions These studies use a well-characterized model of persistence-prone viral infection to reveal a critical deficiency of CD8+ T-cell responses in murine WASP deficiency, in which abrogated production of IFN-I by DCs might play an important contributory role. These findings might help us to understand the immunodeficiency of WAS.

IFN-γ licenses CD11b+ cells to induce progression of systemic lupus erythematosus

Autoantibodies are a hallmark of autoimmune diseases, such as rheumatoid arthritis, autoimmune hepatitis, and systemic lupus erythematosus (SLE). High titers of anti-nuclear antibodies are used as surrogate marker for SLE, however their contribution to pathogenesis remains unclear. Using murine model of SLE and human samples, we studied the effect of immune stimulation on relapsing of SLE. Although autoantibodies bound to target cells inxa0vivo, only additional activation of CD8(+) T cells converted this silent autoimmunity into overt disease. In mice as well as in humans CD8(+) T cells derived IFN-γ enhanced expression of Fc-receptors on CD11b(+) cells. High expression of Fc-receptors allowed CD11b(+) cells to bind to antibody covered target cells and to destroy them inxa0vivo. We found that autoantibodies induce clinically relevant disease when adaptive immunity, specific for disease non-related antigen, is activated.

Systemic inflammation after aortic cross clamping is influenced by Toll-like receptor 2 preconditioning and deficiency

BACKGROUNDnThe perioperative morbidity and mortality of abdominal aortic aneurysm repair is linked to systemic inflammation. Important triggers of the latter are Toll-like receptors (TLRs), which play a central role in innate immunity. Ischemia/reperfusion (I/R) injury can be influenced by either TLR stimulation before I/R (preconditioning) or TLR dysfunction (deficiency or polymorphism). The influence of TLR2 stimulation or deficiency on systemic cytokine release and organ damage after aortic cross clamping has not been evaluated yet.nnnMETHODSnWild type (WT) and TLR2-deficient mice were subjected to 1 h ischemia and 2 or 4 h reperfusion of the infrarenal aorta. One group of WT mice was preconditioned with the synthetic TLR2 agonist Pam(3)Cys-Ser-Lys(4) (Pam(3)CSK(4)). Sham-operated animals without I/R served as controls. Plasma levels of interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, granulocyte macrophage-colony stimulating factor, tumor necrosis factor-α, alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), and creatinine were measured.nnnRESULTSnI/R injury caused by transient clamping of the infrarenal aorta led to a time-dependent increase of all measured cytokines except IL-4, IL-5, and granulocyte macrophage-colony stimulating factor. This was accompanied by elevated markers of organ damage (ALT, AST, and LDH) except creatinine. Preconditioning with Pam(3)CSK(4) led to lower plasma concentrations of all cytokines, with the exception of anti-inflammatory IL-10 which was significantly upregulated. Furthermore, ALT, AST, and LDH plasma concentrations were lower in the preconditioning group. TLR2-deficient mice similarly showed reduced signs of systemic inflammation and organ damage, although less distinctive. IL-2, IL-6, IL-12, ALT, and LDH were time dependently lower compared with WT mice. IL-10 concentration was higher in TLR2-deficient mice compared with WT.nnnCONCLUSIONSnBoth, preconditioning via TLR2 and TLR2 deficiency, ameliorate systemic inflammation and organ damage during I/R injury caused by clamping of the infrarenal aorta. Compared with untreated WT animals, Pam(3)CSK(4) preconditioned and TLR2-deficient mice showed lower concentrations of pro-inflammatory cytokines, whereas anti-inflammatory IL-10 was elevated in both groups. This was accompanied by reduced organ dysfunction parameters.

Pretreatment with helium does not attenuate liver injury after warm ischemia-reperfusion.

ABSTRACT Preconditioning with noble gases serves as an effective strategy to diminish tissue injury in different organs. The aim of this study was to investigate the influence of pretreatment with the nonanesthetic noble gas helium on hepatic injury after warm ischemia and reperfusion (IR) in comparison to ischemic preconditioning (IPC). Anesthetized and ventilated rats were randomized into six groups (n = 8/group): sham: after laparotomy, the portal triad was exposed without clamping; IPC was performed with 10 min of partial liver ischemia and 10 min of reperfusion; HePC: three cycles of 5 min with inhalation of helium 70 vol% and intermittent washout; IR: 45 min of ischemia followed by 240 min of reperfusion; IPC-IR: IPC followed by hepatic IR; HePC-IR: pretreatment with helium 70 vol% followed by hepatic IR. Hepatic injury was evaluated by measurement of serum enzymes aspartate aminotransferase and alanine aminotransferase. Hepatic mRNA expression and serum levels of tumor necrosis factor &agr; (TNF-&agr;) and interleukin 10 (IL-10) were measured with real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Myeloperoxidase in liver tissue was assessed spectrophotometrically as a marker of neutrophil accumulation. mRNA levels of heme oxygenase 1 in liver tissue were assessed to investigate a protein of the most abundant protective system in the liver. Aspartate aminotransferase and alanine aminotransferase serum activities increased after hepatic IR (sham vs. IR; P < 0.05). The serum levels of liver enzymes after IR were significantly diminished with IPC (P < 0.05), whereas helium pretreatment had no effect. mRNA expression of TNF-&agr; increased in all groups except IPC-IR compared with sham, whereas mRNA expression of IL-10 increased only after helium pretreatment. Serum levels of IL-10 were not affected by any intervention, whereas serum levels of TNF-&agr; and liver myeloperoxidase were increased after IR, but not after HePC-IR. In conclusion, pretreatment with inhaled helium does not attenuate hepatic injury after warm IR of the liver, although there is evidence for a modulation of the inflammatory response.

Serum and mucosal antibodies fail as prognostic markers during critical influenza A infection

BACKGROUNDnPrevious studies have indicated that the absence of serum antibodies to influenza A H1N1 virus on day 4 after onset of symptoms predicted a fatal outcome in patients critically ill with influenza. The underlying mechanism was suggested to be the trapping of anti-influenza antibodies in pulmonary immune complexes.nnnOBJECTIVESnTo study serum and mucosal antibodies as prognostic markers in patients with severe influenza A H1N1 infection.nnnSTUDY DESIGNnBlood and respiratory samples (n=324) from 12 patients with severe influenza were analysed for anti-H1N1 antibodies with and without immune complex dissociation from symptom onset until convalescence or death (follow up 14-169 days). Eleven healthy subjects were analysed for comparison.nnnRESULTSnOne of the 12 patients died from influenza pneumonia and had no detectable anti-H1N1 serum antibodies. However, also 2 of the 11 surviving patients remained negative for anti-H1N1 serum antibodies during follow-up (20 and 41 days, respectively). In six of the 11 survivors serum antibodies on day 4 were negative, but turned positive between day 7 and 23. In the remaining 3 patients antibodies were detected in the first 4 days of illness. Mucosal IgG or IgA was detected in all of the patients regardless of their clinical outcome and in 4 of 11 healthy subjects. No mucosal immune complexes were found in the patient who died but were detected in 3 of the 11 survivors.nnnCONCLUSIONSnThis study suggests that no prognostic conclusions can be drawn from anti-H1N1 serum and mucosal antibodies in patients with severe influenza.