**5.1 Free radical cause nitric oxide**

Peroxynitrite converts low density lipoprotein to a form recognized by the macrophage scavenger receptor and that this process is associated with modification of the protein and lipid, and with the oxidation of alpha-tocopherol to alpha-tocopherol quinine [85]. The activated macrophages are involved in the production of large amounts of nitric oxide and indirectly diminish lymphocyte proliferation [86]. Tyrosine nitration is recognized as a prevalent and significant post-translational protein modification that serves as an indicator of nitric oxide-mediated oxidative inflammatory reactions [87]. Prolonged iNOS expression peroxynitrite may exacerbate inflammatory responses mediated by NF-kappaB due to prolonged inducible nitric oxide synthase [88].

NO regulates the structural and functional activity of many immune and inflammatory cells like macrophages, T lymphocytes, antigen-presenting cells, mast cells, neutrophils, and natural killer cells [89]. The proinflammatory nature of NO is actively involved in the process of inflammation only at higher concentrations [90]. The macrophages in active state are actively engaged in the production of not only NO production but also TNFα production [91]. Stimulatory effects of NO on integrin β1 expression and Talin phosphorylation were mediated by the cGMP signaling pathway, which is likely involved in wound healing [92].
