**7. Hypertension**

In PsO patients a higher occurrence of hypertension compared with controls has been reported. The underlying mechanism of hypertension in psoriasis has been discussed and multiple hypothesis have been emerged on this topic (Gottlieb A et al, 2008).

The pathogenesis of hypertension in psoriasis seems to be linked to increased production of angiotensinogen by adipose tissue, subsequently converted to angiotensin II through angiotensin converting enzyme (ACE) (Armstrong AW et al, 2011).

ACE serum levels are increased in psoriasis patients (Gottlieb A et al, 2008).

Angiotensin II not only promotes salt retention by kidney but also it regulates vascular tone, acting a vasoconstrictor and stimulates T-cell proliferation promoting inflammation and the development of atherosclerosis (Armstrong AW et al, 2011).

The association between psoriasis and hypertension may also be attributed to the increased oxidative stress in psoriasis patients. Greater levels of reactive oxygen species can damage endothelium-dependent vasodilation (Armstrong AW et al, 2011).

Other studies emphasized the role of endothelin-1 in hypertension development among PsO patients. Endothelin-1 is a protein produced by several different cell types including keratinocytes; it induces blood vessels vasoconstriction increasing blood pressure. In PsO patients endothelin-1 expression appears to be altered in lesional skin and serum and correlated to psoriasis disease severity (Armstrong AW et al, 2011).
