Targeting the Annexin A1-FPR2/ALX pathway for host-directed therapy in dengue disease.

Host immune responses contribute to dengue's pathogenesis and severity, yet the possibility that failure in endogenous inflammation resolution pathways could characterise the disease has not been contemplated. The pro-resolving protein Annexin A1 (AnxA1) is known to counterbalance overexuberant inflammation and mast cell (MC) activation. We hypothesised that inadequate AnxA1 engagement underlies the cytokine storm and vascular pathologies associated with dengue disease. Levels of AnxA1 were examined in the plasma of dengue patients and infected mice. Immunocompetent, interferon (alpha and beta) receptor one knockout (KO), AnxA1 KO, and formyl peptide receptor 2 (FPR2) KO mice were infected with dengue virus (DENV) and treated with the AnxA1 mimetic peptide Ac2-26 for analysis. In addition, the effect of Ac2-26 on DENV-induced MC degranulation was assessed in vitro and in vivo. We observed that circulating levels of AnxA1 were reduced in dengue patients and DENV-infected mice. Whilst the absence of AnxA1 or its receptor FPR2 aggravated illness in infected mice, treatment with AnxA1 agonistic peptide attenuated disease manifestationsatteanuated the symptoms of the disease. Both clinical outcomes were attributed to modulation of DENV-mediated viral load-independent MC degranulation. We have thereby identified that altered levels of the pro-resolving mediator AnxA1 are of pathological relevance in DENV infection, suggesting FPR2/ALX agonists as a therapeutic target for dengue disease.

Circulating levels of High-mobility group box 1 protein and nucleosomes are associated with outcomes after liver transplant.

BACKGROUND: Liver transplantation (LT) can be associated with early complications, such as allograft dysfunction and acute kidney injury, which contribute significantly to morbidity and mortality. High-mobility group box 1 protein (HMGB1) has been identified as mediator in ischemia-reperfusion injury. Nucleosomes are complexes formed by DNA and histone proteins, and histones contribute to organs failure and death during sepsis. METHODS: HMGB1 and nucleosome plasma levels were measured, by enzyme-linked immunosorbent assays, during LT and in the first 48 post-operative hours in 22 LT patients. The association between HMGB1 and nucleosome levels and the complications and survival within 6 months after LT were investigated. RESULTS: We observed peak HMGB1 and nucleosome levels after graft reperfusion. HMGB1 and nucleosome levels were associated with the occurrence of acute kidney injury, early allograft dysfunction, and early survival after LT. Nucleosome levels after graft reperfusion were associated with the occurrence of systemic inflammatory response syndrome. CONCLUSIONS: HMGB1 and nucleosome levels increased after liver reperfusion in human LT setting and were associated with early complications and survival. New studies are necessary to explore their role as early markers of hepatocellular injury in human LT and the risk of graft and organs dysfunction and death.

Effects of Tityus serrulatus scorpion venom on thromboelastogram in rats.

Thromboelastometry was used to evaluate blood coagulation in anesthetized rats after intravenous administration of Tityus serrulatus scorpion venom (Tx). Tracheostomy followed by catheterization of the left jugular vein and right carotid artery were performed for Tx or Ringer's lactate solution injection and blood sample harvesting, respectively. Blood samples were obtained at the beginning of the experiments (baseline) and at two, five, 15, 30, and 60 min after intoxication. The following coagulation parameters were analyzed: CT (Clotting Time), CFT (Clotting Formation Time), Alpha Angle (α), MCF (Maximum Clot Firmness) and TPI (Thrombodynamic Potential Index). Toxin-induced hypercoagulability was demonstrated at the 15 and 60 min. We hypothesize Tx-induced hypercoagulability and enhanced clot formation could be explained by catecholamine release, systemic inflammatory response, and complement system activation, at least in the first hour after envenomation. Further studies are needed to determine the molecular mechanism of Tx-induced coagulopathy.