SUMMARY The insulin receptor-related receptor (IRR), an orphan receptor tyrosine kinase of the insulin receptor family, can be activated by alkaline media both in vitro and in vivo at pH>7.9. The alkali-sensing property of IRR is conserved in frog, mouse and human. IRR activation is specific, dose-dependent, quickly reversible and demonstrates positive cooperativity. It also triggers receptor conformational changes and elicits intracellular signaling. The pH sensitivity of IRR is primarily defined by its L1F extracellular domains. IRR is predominantly expressed in organs that come in contact with mildly alkaline media. In particular, IRR is expressed in the cell subsets of the kidney that secrete bicarbonate into urine. Disruption of IRR in mice impairs the renal response to alkali loading attested by development of metabolic alkalosis and decreased urinary bicarbonate excretion in response to this challenge. We therefore postulate that IRR is an alkali sensor that functions in the kidney to manage metabolic bicarbonate excess.

In this study, we checked whether HSP70 preparations of different origins are able to protect model animals (rats) from endotoxic shock and modify the response of myeloid cells to lipopolysaccharide (LPS) challenge. It was shown that HSP70 preparations can effectively protect organisms from endotoxic shock by strongly decreasing mortality and restoring both homeostasis and various hemodynamic characteristics. At the cellular level, HSP70 preparations significantly inhibit LPS-induced reactive oxygen species production in various myeloid cells and decrease NO expression in macrophages, which is enhanced after LPS priming. In parallel, HSP70 preconditioning partially normalizes neutrophil apoptosis, which is disturbed as a result of LPS stimulation. These results suggest that the antiseptic actions of HSP70 preparations are probably realized at the level of receptor membrane complexes of myeloid cells, which represent the major target of LPS action. Taken together, our findings show that extracellular mammalian HSP70 may play an important role in innate immunity modulation and stimulation of endogenous protective mechanisms, both at the cellular and organism levels, which make this protein a promising base for the development of efficient antiseptic drugs.

It has been previously reported that pretreatment with exogenous heat shock protein 70 (Hsp70) is able to protect cells and animals from the deleterious effects of bacterial lipopolysaccharide (LPS) produced by Gramnegative bacteria. However, the effects of Hsp70 pretreatment on lipoteichoic acid (LTA) challenge resulted from Gram-positive bacteria infection have not been fully elucidated. In this study, we demonstrated that preconditioning with human recombinant Hsp70 ameliorates various manifestations of systematic inflammation, including reactive oxygen species, TNFα, and CD11b/CD18 adhesion receptor expression induction observed in different myeloid cells after LTA addition. Therefore, exogenous Hsp70 may provide a mechanism for controlling excessive inflammatory responses after macrophage activation. Furthermore, in a rat model of LTA-induced sepsis, we demonstrated that prophylactic administration of exogenous human Hsp70 significantly exacerbated numerous homeostatic and hemodynamic disturbances induced by LTA challenge and partially normalized the coagulation system and multiple biochemical blood parameters, including albumin and bilirubin concentrations, which were severely disturbed after LTA injections. Importantly, prophylactic intravenous injection of Hsp70 before LTA challenge significantly reduced mortality rates. Thus, exogenous mammalian Hsp70 may serve as a powerful cellular defense agent against the deleterious effects of bacterial pathogens, such as LTA and LPS. Taken together, our findings reveal novel functions of this protein and establish exogenous Hsp70 as a promising pharmacological agent for the prophylactic treatment of various types of sepsis.

Tuberculosis is known to be the biggest global health problem, causing the most deaths by a single infectious agent. Vaccine-development efforts are extremely important. This paper represents the results of the first-in-human trial of recombinant subunit tuberculosis vaccine GamTBvac in a Phase I study. GamTBvac is a new BCG booster candidate vaccine containing dextran-binding domain modified Ag85a and ESAT6-CFP10 MTB antigens and CpG ODN adjuvant, formulated with dextrans. Safety and immunogenicity of GamTBvac were estimated in an open-label clinical trial on 60 Mycobacterium tuberculosis uninfected (MTB-uninfected) volunteers previously-vaccinated with Bacillus Calmette—Guérin vaccine (BCG). The candidate vaccine had an acceptable safety profile and was well-tolerated. Three different vaccine doses with a double-immunization scheme were assessed for immunogenicity and induced a significant increase in IFN-γ in-house IGRA response and IgG ELISA analysis. Among them, the half dose vaccine group (containing DBD-ESAT6-CFP10, 12.5 μg; DBD-Ag85a, 12.5 μg; CpG (ODN 2216), 75 μg; DEAE-Dextran 500 kDa, 250 μg; and Dextran 500 kDa, 5 mg) provided high, early and stable in time immune response specific to both protein antigen fusions and is proposed for the further studies.

Apolipoprotein E (apoE) is the primary apolipoprotein synthesized in the brain in response to injury with known neuroprotective effects exerted through antioxidant, antiinflammatory, antiexcitotoxic, and neurotrophic mechanisms. We have previously demonstrated that COG1410, an apoE mimetic peptide, exerts neuroprotective and antiinflammatory effects in a murine model of traumatic brain injury (TBI). As in TBI, ischemia-reperfusion injury is a component of acute stroke, which displays a pharmacogenetic association with the APOE4 gene. Using an intraluminal middle cerebral occlusion (MCAO) model in rats, we found that a single intravenous injection of COG1410 at 120 min post-MCAO significantly improved vestibulomotor function, decreased poststroke locomotor asymmetry, and decreased infarct volume of the ipsilateral hemisphere. These results support further exploration of a novel apoE-mimetic peptide, COG1410, as a therapeutic treatment for stroke.