A growing body of evidence shows that sildenafil (Viagra) exerts immunomodulatory effects. Its positive action was demonstrated in treating severe autoimmune diseases and cancer. In addition, anti-inflammatory and anti-aggregation effects of sildenafil have also been reported. In tumor-bearing mice, the inhibition of PDE5 activity with sildenafil prolonged the survival of the animals through augmentation of antitumor immunity.
Daily sildenafil treatment from EAE symptom onset prevented further clinical deterioration and improved neurogenesis. Sildenafil decreased the levels of proinflammatory cytokines, including TNF-α, IL-1, and reduced NK cells activity, and enhanced the action of regulatory T cells. Sildenafil markedly inhibited iROS production induced by LPS.
Type 5 phosphodiesterase (PDE5) inhibitor increased endothelial cell cGMP and promoted angiogenesis by increasing the expression of VEGF. De novo blood vessel formation is essential for embryonic vascular development and for postnatal vascular homeostasis and wound healing.
Thus, the available data suggest that sildenafil could find use in the treatment of autoimmune, neurodegenerative, and cardiovascular diseases, as well as recurrent abortions. However, the potential immunomodulatory effects of sildenafil in humans remain to be confirmed.
