Cellular and molecular mechanisms of inflammation-induced angiogenesis.

Blood vessel formation is a fundamental process for the development of organism and tissue regeneration. Of importance, angiogenesis occurring during postnatal development is usually connected with inflammation. Here, we review how molecular and cellular mechanisms underlying inflammatory reactions regulate angiogenesis. Inflamed tissues are characterized by hypoxic conditions and immune cell infiltration. In this review, we describe an interplay of hypoxia-inducible factors (HIFs), HIF1 and HIF2, as well as NF-κB and nitric oxide in the regulation of angiogenesis. The mobilization of macrophages and the differential role of M1 and M2 macrophage subsets in angiogenesis are also discussed. Next, we present the current knowledge about microRNA regulation of inflammation in the context of new blood vessel formation. Finally, we describe how the mechanisms involved in inflammation influence tumor angiogenesis. We underlay and discuss the role of NF-E2-related factor 2/heme oxygenase-1 pathway as crucial in the regulation of inflammation-induced angiogenesis.