Involvement of microRNAs in the inflammatory pathways of pulmonary sarcoidosis.

Sarcoidosis is a multi-organ disease in which affected tissues are invaded with non-necrotizing granulomatous structures, mostly consisted of T helper 1 (Th1) cells and multinucleate giant cells. However, the etiology and pathogenesis of sarcoidosis is not known and the diagnosis is usually based on clinical examination involving radiography and histopathological analysis of biopsies of affected organs. Although the knowledge on the molecular background of sarcoidosis is limited, it seems that the important pathways involve transforming growth factor-ß (TGF-ß) and JAK/STAT, which may influence the interferon-γ (IFN-γ)-mediated signaling. Additionally, recently the role of microRNAs (miRNAs), the small non-coding RNA molecules, has been emphasized in different pathological conditions including autoimmune diseases. This review summarizes the current knowledge on the molecular pathways in the pathogenesis of sarcoidosis with a special emphasis on cytokines and miRNAs controlling immune cells proliferation and differentiation. Moreover, the possible role of T regulatory cells (CD4(+) CD25(+) FoxP3(+)) in this disease has been discussed.

Long-term VEGF-A expression promotes aberrant angiogenesis and fibrosis in skeletal muscle.

Vascular endothelial growth factor A (VEGF-A) induces strong angiogenesis and it has been widely used in proangiogenic gene therapy studies. However, little is known about long-term effects of VEGF-A expression in skeletal muscle. Here the long- term effects of adeno-associated virus (AAV) encoding human VEGF-A(165) (AAV-VEGF-A) gene transfer in normal and ischemic rabbit hindlimb skeletal muscles were studied. AAV-LacZ was used as a control. In one-year follow-up, a remarkable increase in skeletal muscle perfusion compared with AAV-LacZ was observed measured with Doppler and contrast pulse sequence ultrasound. Angiogenesis was also seen in histology as enlarged and sprouting capillaries. In addition to favorable angiogenic effects, aberrant vascular structures with CD31 positive cell layers were seen inside muscle fibers after AAV-VEGF-A gene transfer. Importantly, we found increased amounts of extracellular matrix with a high number of macrophages and fibrosis in AAV-VEGF-A transduced muscles. No changes in skeletal muscle morphology were detected in AAV-LacZ transduced muscles. Our results indicate that local AAV-VEGF-A gene transfer efficiently promotes long-term angiogenesis in large animal model. However, non-regulated expression of VEGF-A causes unfavorable changes in muscle morphology, which suggests the need for regulation of the transgene expression in long-term AAV-mediated VEGF-A gene transfer applications.

Heme oxygenase-1-dependent and -independent regulation of angiogenic genes expression: effect of cobalt protoporphyrin and cobalt chloride on VEGF and IL-8 synthesis in human microvascular endothelial cells.

Induction of heme oxygenase-1 (HO-1) expression can be achieved by stimulation with cobalt protoporphyrin (CoPPIX) or cobalt chloride (CoCl2). HO-1 has been recently implicated in regulation of angiogenesis and CoCl2 is known to potently activate hypoxia inducible factor-1 (HIF-1) transcription factor, a key regulator of angiogenic response in hypoxia. Here we determined the effect of CoPPIX and CoCl2 on the expression of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8), the two major angiogenic mediators, in human microvascular endothelial cells (HMEC-1). CoPPIX induced HO-1 expression and strongly enhanced VEGF and IL-8 synthesis, through the activation of VEGF and IL-8 promoters. Inhibition of HO activity by SnPPIX decreased VEGF production, while, interestingly, it did not affect IL-8. CoCl2 activated hypoxia-responsive element (HRE) and consequently VEGF generation via the enhancement of production of reactive oxygen species (ROS). On the other hand, CoCl2 did not influence IL-8 expression, while CoPPIX did not induce ROS elevation neither it affected HRE activity in VEGF promoter. Our data show that although both CoCl2 and CoPPIX induce HO-1, the influence of CoCl2 on VEGF does not involve HO-1 and is HIF-1-dependent, while the effect of CoPPIX does not involve HIF-1 but relies on HO-1.

Effects of plant extracts on angiogenic activities of endothelial cells and keratinocytes.

Numerous bioactive chemical compounds of plant origin may influence the angiogenic activity of various cell types and may thus affect the formation of blood vessels. Here we present the angiogenic effects of extracts of edible plants collected in Crete, Southern Italy and Southern Spain. Extracts have been applied to cultured human microvascular endothelial cells (HMEC-1), human umbilical vein endothelial cells (HUVEC) and human keratinocytes (HaCaT). About half out of 96 extracts exerted an inhibitory effect on HMEC-1 proliferation. Additionally, we have noted the inhibitory effects of extracts on HUVEC differentiation on a Matrigel layer. None of the extracts showed a stimulatory activity. The extract of Thymus piperella exerted moderate inhibitory effect on cobalt-chloride induced VEGF synthesis, however, CoCl(2)-induced activation of hypoxia responsive element of VEGF promoter was significantly attenuated only by extract of Origanum heracleoticum. Our study indicates that extracts of local food plants, of potential value as nutraceuticals, contain chemical compounds which may inhibit angiogenesis. Demonstration of their real influence on human health requires, however, extensive animal studies and controlled clinical investigations.