Adiponectin Fails in Improving Angiogenic Repair in Streptozocin-Treated or Leprdb/db Mice after Hind Limb Ischemia

Type 1 and 2 diabetes carry risk factors for the development of microvascular diseases with associated impairment of angiogenic repair. Here, we investigated whether adiponectin, an adipocyte-specific adipocytokine with antiatherosclerotic and antidiabetic properties, regulates angiogenic repair in response to tissue ischemia in Leprdb/db and streptozocin-treated diabetic mouse models. Methods. Adenoviral vectors containing the gene for β-galactosidase, full-length mouse adiponectin, and dominant-negative AMPKα2 were used in streptozocin-treated male Leprdb/db mice, after which hind limb blood flow was measured using a laser doppler blood flow analyzer. Results. The angiogenic repair of ischemic hind limbs was impaired in both streptozocin-treated and Leprdb/db mice compared to wild-type mice as evaluated by laser doppler flow and capillary density analyses. Adenovirus-mediated administration of adiponectin accelerated angiogenic repair after hind limb ischemia in WT mice, but not in Leprdb/db mice or mice treated with streptozocin. In vitro experiments using HUVECs highlighted the antiapoptotic and proangiogenic properties of adiponectin but could not demonstrate accelerated differentiation of endothelial cells into tube- like structures at elevated glucose levels. Conclusions. External administration of adiponectin at elevated glucose levels may not be useful in the treatment of diabetes mellitus-related vascular deficiency diseases

Angiogenic-regulatory network revealed by molecular profiling heart tissue following Akt1 induction in endothelial cells

Akt is a pivotal signaling molecule involved in the regulation of angiogenesis. In order to further elucidate the role of Akt1 in blood vessel development, a tetracycline-regulated transgenic system was utilized to conditionally activate Akt1 signaling in endothelial cells to examine transcript expression changes associated with angiogenesis in the heart. Induction of Akt1 over the course of 6 weeks led to a 33% increase in capillary density without affecting overall heart growth. Transcript expression profiles in the hearts were analyzed with an Affymetrix GeneChip Mouse Expression Set 430 2.0, which represents approximately 45,000 cDNAs and ESTs. A total of 248 transcripts were differentially expressed between transgenic and control mice (fold change >/<1.8; false discovery rate < 0.1; P < 0.01). A subset of these differentially expressed transcripts included angiogenic growth factors, cytokines, and extracellular matrix proteins. More specifically, these transcripts included VEGF-receptor2, neuropilin-1, and connective tissue growth factor, each of which is implicated in blood vessel growth and the maintenance of vessel wall integrity. Furthermore, these factors may be involved in an autocrine-regulatory feedback system, one believed to promote vessel growth. Knowledge of these and other targets could be used to treat ischemic heart disease, a disease whose broad spectrum of manifestations range from patients with only effort-induced angina without myocardial damage, through stages of myocardial ischemia that are associated with reversible and irreversible impairment in left ventricular function, to states of irreversible myocardial injury and necrosis resulting in congestive heart failure (CHF). © 2008 Springer Science+Business Media B.V

Cathepsin G is differentially expressed in primary human antigen-presenting cells

Cathepsins are required for the processing of antigens in order to make them suitable for loading on major histocompatibility complex (MHC) class II molecules, for subsequent presentation to CD4(+) T cells. It was shown that antigen processing in monocyte-derived dendritic cells (DC), a commonly used DC model, is different from that of primary human DC. Here, we report that the two subsets of human myeloid DC (mDC) and plasmacytoid DC (pDC) differ in their cathepsin distribution. The serine protease cathepsin G (CatG) was detected in mDC1, mDC2, pDC, cortical thymic epithelial cells (cTEC) and high levels of CatG were determined in pDC. To address the role of CatG in the processing and presentation of a Multiple Sclerosis-associated autoantigen myelin basic protein (MBP), we used a non-CatG expressing fibroblast cell line and fibroblasts, which were preloaded with purified CatG. We find that preloading fibroblasts with CatG results in a decrease of MBP84-98-specific T cell proliferation, when compared to control cells. Our data suggest a different processing signature in primary human antigen-presenting cells and CatG may be of functional importance