Glucocorticoids probably improve outcomes in patients hospitalised for community acquired pneumonia (CAP). In this a priori planned exploratory subgroup analysis of the phase 3 randomised controlled Activated Protein C and Corticosteroids for Human Septic Shock (APROCCHSS) trial, we aimed to investigate responses to hydrocortisone plus fludrocortisone between CAP and non-CAP related septic shock.

As the COVID-19 pandemic continues, researchers seek to identify efficacious treatments. Current approaches to COVID-19 therapeutics focus on antiviral agents, convalescent plasma, monoclonal antibodies, immunomodulators and more traditional therapies such as steroids [1-6]. Reversing disturbances in coagulation has also been identified as a priority area for candidate therapies, such as through the Accelerating COVID-19 Therapeutic Interventions and Vaccines 4 adaptive clinical trial (ACTIV-4) which is currently evaluating aspirin, heparins and apixaban [7]. Since there is a clear relationship between mechanisms of coagulation and the immune response, it is possible that reversing disturbances in coagulation may diminish the dysregulated immune response observed in COVID-19. The basis for this hypothesis is described below and is followed by discussion of a proposed candidate therapy - activated protein C. By treating COVID-19 patients using a novel approach, which does not focus on immune-based or antiviral treatments, but instead which addresses both the anti-thrombotic and inflammatory consequences of infection, the hope is that new therapeutic targets can be considered and new candidate therapies, such as activated protein C, may be evaluated.

In this work, a selective and simple electrochemical aptasensor was developed for the detection of activated protein C by employing methylene blue (MB) as a redox indicator. An activated protein C aptamer (APC-apt) was covalently immobilized on the surface of a carbon paste electrode modified with gold nanoparticle - chitosan /graphene paste (AuNPs-Chi/Gr). The AuNPs-Chi/Gr paste increased electrochemical peak current and immobilized the aptamer on the electrode surface. The process of aptasensor construction and successful immobilization of the aptamer on the electrode surface was confirmed by electrochemical cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to determine the methylene blue peak current. By replacing APC instead of MB at the electrode surface, the cathodic current of the MB decreases, and this decrease corresponds to the APC concentration. Under optimum conditions, the APC concentration was detected in the range from of 0.1 ng·mL-1 to 40 μg·mL-1 with a relatively low detection limit of 0.073 ng·mL-1. This method was then applied to the determination of APC in human serum samples. The results revealed that this strategy can be used to measure other proteins in biological samples.

Activated protein C (APC) exerts diverse cell signaling pathways which results in multiple distinct cytoprotective actions. These include anti-apoptotic and anti-inflammatory activities and stabilization of endothelial and epithelial barriers. We studied the ability of APC to inhibit the leakage and the growth of newly formed as well as pre-existing choroidal neovascularization (CNV) and examined the ability of APC to stabilize the Retinal Pigmented Epithelium (RPE). We explored the contribution of Tie2 receptor to the protective effects of APC. CNV was induced by laser photocoagulation in C57BL/6J mice. APC was injected intravitreally immediately or 7 days after CNV induction. Neovascularization was evaluated on RPE-choroidal flatmounts using FITC-dextran perfusion and CD31 immunofluorescence. CNV leakage was measured by fluorescein angiography (FA). The ability of APC to stabilize the RPE barrier was evaluated in-vitro by dextran permeability and zonula occludens 1 (ZO1) immunostaining. Tie2 blocking was induced in-vivo by intraperitoneal injection of Tie2 kinase inhibitor and in-vitro by incubation with anti Tie2 antibodies. APC treatment dramatically inhibited the generation of newly formed CNV leakage sites and reversed leakage in 85% of the pre-existing CNV leaking sites. In RPE cell culture, APC induced translocation of ZO1 to the cell membrane, accompanied by reduction in permeability of the monolayer. Inhibition of Tie2 significantly decreased APC protective activities in both the mouse model and the RPE cell culture. Our results show that APC treatment significantly inhibits the leakage and growth of newly formed, as well as pre-existing CNV, and its protective activities are partially mediated via the Tie2 receptor. The data suggest that APC should be further investigated as a possible effective treatment for CNV.

Intravitreally administered activated protein C in 10 eyes with ischemic central retinal vein occlusion significantly improved macular edema; in 5 eyes, the reperfusion of the retinal nonperfused areas exceeded 50% of baseline.

Thrombin aggravates ischemic stroke and activated protein C (APC) has a neuroprotective effect. Both proteases interact with protease-activated receptor 1, which exhibits functional selectivity and leads to G-protein- and β-arrestin-mediated-biased signal transduction. We focused on the effect of β-arrestin in PAR-1-biased signaling on endothelial function after stroke or high-fat diet (HFD). Thrombin had a rapid disruptive effect on endothelial function, but APC had a slow protective effect. Paralleled by prolonged MAPK 42/44 signaling activation by APC via β-arrestin-2, a lower cleavage rate of PAR-1 for APC than thrombin was quantitatively visualized by bioluminescence video imaging. HFD-fed mice showed lower β-arrestin-2 levels and more severe ischemic injury. The expression of β-arrestin-2 in capillaries and PDGF-β secretion in HFD-fed mice were reduced in penumbra lesions. These results suggested that β-arrestin-2-MAPK-PDGF-β signaling enhanced protection of endothelial function and barrier integrity after stroke.

Sepsis is a major health problem all over the world. Despite its existence since the time of Hippocrates (470 BC), sepsis is still a serious medical problem for physicians working in both pediatric and adult intensive care units. The most current US FDA-approved drug called recombinant human activated protein C or Drotrecogin-α is also failed in clinical trials and showed similar effects as placebo. The epidemiological data and studies have indicated sepsis as a major socioeconomic burden all over the world. Advances in immunology and genomic medicine have established different immunological mechanisms as major regulators of the pathogenesis of the sepsis. These immunological mechanisms come into action upon activation of several components of the immune system including innate and adaptive immunity. The activation of these immune cells in response to the pathogens or pathogen-associated molecular patterns (PAMPs) responsible for the onset of sepsis is regulated by the metabolic stage of the immune cells called immunometabolism. An alternation in the immunometabolism is responsible for the generation of dysregulated immune response during sepsis and plays a very important role in the process. Thus, it becomes vital to understand the immunometabolic reprograming during sepsis to design future target-based therapeutics depending on the severity. The current review is designed to highlight the importance of immune response and associated immunometabolism during sepsis and its targeting as a future therapeutic approach.

Disseminated intravascular coagulation (DIC) is an acquired clinicobiological syndrome characterized by widespread activation of coagulation leading to fibrin deposition in the vasculature, organ dysfunction, consumption of clotting factors and platelets, and life-threatening hemorrhage. Disseminated intravascular coagulation is provoked by several underlying disorders (sepsis, cancer, trauma, and pregnancy complicated with eclampsia or other calamities). Treatment of the underlying disease and elimination of the trigger mechanism are the cornerstone therapeutic approaches. Therapeutic strategies specific for DIC aim to control activation of blood coagulation and bleeding risk. The clinical trials using DIC as entry criterion are limited. Large randomized, phase III clinical trials have investigated the efficacy of antithrombin (AT), activated protein C (APC), tissue factor pathway inhibitor (TFPI), and thrombomodulin (TM) in patients with sepsis, but the diagnosis of DIC was not part of the inclusion criteria. Treatment with APC reduced 28-day mortality of patients with severe sepsis, including patients retrospectively assigned to a subgroup with sepsis-associated DIC. Treatment with APC did not have any positive effects in other patient groups. The APC treatment increased the bleeding risk in patients with sepsis, which led to the withdrawal of this drug from the market. Treatment with AT failed to reduce 28-day mortality in patients with severe sepsis, but a retrospective subgroup analysis suggested possible efficacy in patients with DIC. Clinical studies with recombinant TFPI or TM have been carried out showing promising results. The efficacy and safety of other anticoagulants (ie, unfractionated heparin, low-molecular-weight heparin) or transfusion of platelet concentrates or clotting factor concentrates have not been objectively assessed.