Hydroxychloroquine partially prevents endothelial dysfunction induced by anti-beta-2-GPI antibodies in an in vivo mouse model of antiphospholipid syndrome.

BACKGROUND: Antiphospholipid syndrome is associated with endothelial dysfunction, which leads to thrombosis and early atheroma. Given that hydroxychloroquine has anti-thrombotic properties in lupus, we hypothesized that it could reduce endothelial dysfunction in an animal model of antiphospholipid syndrome. We evaluated the effect of hydroxychloroquine in preventing endothelial dysfunction in a mouse model of antiphospholipid syndrome. METHODS: Antiphospholipid syndrome was induced by an injection of monoclonal anti-beta-2-GPI antibodies. Vascular reactivity was evaluated in mesenteric resistance arteries isolated from mice 3 weeks (APL3W) after receiving a single injection of anti-beta-2-GPI antibodies and after 3 weeks of daily oral hydroxychloroquine treatment (HCQ3W) compared to control mice (CT3W). We evaluated endothelial dysfunction by measuring acetylcholine-mediated vasodilation. A pharmacological approach was used to evaluate NO synthase uncoupling (tetrahydrobiopterin) and the generation of reactive oxygen species (Tempol). RESULTS: Impaired acetylcholine-mediated dilation was evidenced in mice 3 weeks after anti-beta-2-GPI antibodies injection compared to CT3W, by reduced maximal dilation (p<0.0001) and sensitivity (pKd) (p = 0.01) to acetylcholine. Hydroxychloroquine improved acetylcholine-dependent dilation, on pKd (p = 0.02) but not maximal capacity compared to untreated mice. The addition of tetrahydrobiopterin (p = 0.02) and/or Tempol (p = 0.0008) improved acetylcholine-mediated dilation in APL3W but not in HCQ3W. CONCLUSIONS: We demonstrated that endothelial dysfunction in mouse resistance arteries persisted at 3 weeks after a single injection of monoclonal anti-beta-2-GPI antibodies, and that hydroxychloroquine improved endothelium-dependent dilation at 3 weeks, through improvement of NO synthase coupling and oxidative stress reduction.

Microvascular vasodilator properties of the angiotensin II type 2 receptor in a mouse model of type 1 diabetes.

Diabetes Mellitus is associated with severe cardiovascular disorders involving the renin-angiotensin system, mainly through activation of the angiotensin II type 1 receptor (AT1R). Although the type 2 receptor (AT2R) opposes the effects of AT1R, with vasodilator and anti-trophic properties, its role in diabetes is debatable. Thus we investigated AT2R-mediated dilatation in a model of type 1 diabetes induced by streptozotocin in 5-month-old male mice lacking AT2R (AT2R-/y). Glucose tolerance was reduced and markers of inflammation and oxidative stress (cyclooxygenase-2, gp91phox p22phox and p67phox) were increased in AT2R-/y mice compared to wild-type (WT) animals. Streptozotocin-induced hyperglycaemia was higher in AT2R-/y than in WT mice. Arterial gp91phox and MnSOD expression levels in addition to blood 8-isoprostane and creatinine were further increased in diabetic AT2R-/y mice compared to diabetic WT mice. AT2R-dependent dilatation in both isolated mesenteric resistance arteries and perfused kidneys was greater in diabetic mice than in non-diabetic animals. Thus, in type 1 diabetes, AT2R may reduce glycaemia and display anti-oxidant and/or anti-inflammatory properties in association with greater vasodilatation in mesenteric arteries and in the renal vasculature, a major target of diabetes. Therefore AT2R might represent a new therapeutic target in diabetes.

Involvement of Heme Oxygenase-1 in particulate matter-induced impairment of NO-dependent relaxation in rat intralobar pulmonary arteries.

Particulate air pollution exerts deleterious effects on cardiovascular system. We previously described that exposure to urban particulate matter (SRM1648) impairs nitric oxide (NO, a major vasculoprotective factor) responsiveness in intrapulmonary arteries. As Heme Oxygenase-1 (HO-1) is induced by urban particles in some cell types and is known to alter NO-dependent signaling pathway, the objective was to characterize HO-1 involvement in SRM1648-induced impairment of NO-dependent relaxation in intrapulmonary arteries. Rat intrapulmonary artery rings were exposed or not to Co (III) Protoporphyrin IX Chloride (HO-1 inducer) or SRM1648 in the absence or presence of Cr (III) Mesoporphyrin IX Chloride (HO-1 activity inhibitor). NO-dependent relaxation was assessed with DEA-NOnoate (DEA-NO) on pre-contracted arteries. HO-1 and soluble guanylyl-cyclase (sGC) mRNA and protein expressions were assessed by qRT-PCR and Western blotting, respectively. SRM1648 or Co (III) Protoporphyrin IX Chloride exposure (24) impaired DEA-NO-dependent relaxation. The SRM-induced alteration of DEA-NO responsiveness was partially prevented by Cr (III) Mesoporphyrin IX Chloride. Co (III) Protoporphyrin IX Chloride induced HO-1 mRNA and protein expressions, whereas SRM1648 only induced HO-1 protein expression without affecting its mRNA level. Exposure to either SRM1648 or to Co (III) Protoporphyrin IX Chloride did not affect the expression levels of sGC. In conclusion, this study provides some evidence that impairment of NO signaling pathway in intrapulmonary arteries involves HO-1. Therefore it highlights the role of HO-1 in particulate matter-induced detrimental effects in pulmonary circulation.

Synthesis of new pyrrolo[1,2-a]quinoxaline derivatives as potential inhibitors of Akt kinase.

Akt kinases are attractive targets for small molecule drug discovery because of their key role in tumor cell survival/proliferation and their overexpression/activation in many human cancers. Recent efforts in the development and biological evaluation of small molecule inhibitors of Akt have led to the identification of novel Akt kinase inhibitors, based on a quinoxaline or pyrazinone scaffold. A series of new substituted pyrrolo[1,2-a]quinoxaline derivatives, structural analogues of these active quinoxaline or pyrazinone pharmacophores, was synthesized from various substituted 2-nitroanilines or 1,2-phenylenediamine via multistep heterocyclization process. These new compounds were tested for their in vitro ability to inhibit the proliferation of the human leukemic cell lines K562, U937 and HL60, and the breast cancer cell line MCF7. Three of these human cell lines (K562, U937 and MCF7) exhibited an active phosphorylated Akt form. The most promising active pyrroloquinoxalines were found to be 1a that inhibited K562 cell line proliferation with an IC(50) of 4.5 microM, and 1h that inhibited U937 and MCF7 cell lines with IC(50) of 5 and 8 microM, respectively. These two candidates exhibited more potent activities than the reference inhibitor A6730.