Hydrogen Peroxide Induced Toxicity Is Reversed by the Macrocyclic IRAP-Inhibitor HA08 in Primary Hippocampal Cell Cultures

Angiotensin IV (Ang IV), a metabolite of Angiotensin II, is a bioactive hexapeptide that inhibits the insulin-regulated aminopeptidase (IRAP). This transmembrane zinc metallopeptidase with many biological functions has in recent years emerged as a new pharmacological target. IRAP is expressed in a variety of tissues and can be found in high density in the hippocampus and neocortex, brain regions associated with cognition. Ang IV is known to improve memory tasks in experimental animals. One of the most potent IRAP inhibitors known today is the macrocyclic compound HA08 that is significantly more stable than the endogenous Ang IV. HA08 combines structural elements from Ang IV and the physiological substrates oxytocin and vasopressin, and binds to the catalytic site of IRAP. In the present study we evaluate whether HA08 can restore cell viability in rat primary cells submitted to hydrogen peroxide damage. After damaging the cells with hydrogen peroxide and subsequently treating them with HA08, the conceivable restoring effects of the IRAP inhibitor were assessed. The cellular viability was determined by measuring mitochondrial activity and lactate dehydrogenase (LDH) release. The mitochondrial activity was significantly higher in primary hippocampal cells, whereas the amount of LDH was unaffected. We conclude that the cell viability can be restored in this cell type by blocking IRAP with the potent macrocyclic inhibitor HA08, although the mechanism by which HA08 exerts its effects remains unclear

Modular multiantigen T cell epitope-enriched DNA vaccine against human leishmaniasis.

The leishmaniases are protozoal diseases that severely affect large populations in tropical and subtropical regions. There are only limited treatment options and preventative measures. Vaccines will be important for prevention, control and elimination of leishmaniasis, and could reduce the transmission and burden of disease in endemic populations. We report the development of a DNA vaccine against leishmaniasis that induced T cell-based immunity and is a candidate for clinical trials. The vaccine antigens were selected as conserved in various Leishmania species, different endemic regions, and over time. They were tested with T cells from individuals cured of leishmaniasis, and shown to be immunogenic and to induce CD4(+) and CD8(+) T cell responses in genetically diverse human populations of different endemic regions. The vaccine proved protective in a rodent model of infection. Thus, the immunogenicity of candidate vaccine antigens in human populations of endemic regions, as well as proof of principle for induction of specific immune responses and protection against Leishmania infection in mice, provides a viable strategy for T cell vaccine development