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Journal of Immunology Research
Volume 2017, Article ID 4541958, 8 pages
https://doi.org/10.1155/2017/4541958
Review Article

Sildenafil Can Affect Innate and Adaptive Immune System in Both Experimental Animals and Patients

Department of Clinical Immunology, Institute of Transplantology, Medical University of Warsaw, Nowogrodzka 59, 02-006 Warsaw, Poland

Correspondence should be addressed to Monika Kniotek; lp.pw@ketoinkm

Received 17 September 2016; Revised 20 November 2016; Accepted 20 December 2016; Published 20 February 2017

Academic Editor: Eyad Elkord

Copyright © 2017 Monika Kniotek and Agnieszka Boguska. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sildenafil, a type 5 phosphodiesterase inhibitor (PDE5-I), is primarily used for treating erectile dysfunction. Sildenafil inhibits the degradation of cyclic guanosine monophosphate (cGMP) by competing with cGMP for binding site of PDE5. cGMP is a secondary messenger activating protein kinases and a common regulator of ion channel conductance, glycogenolysis, and cellular apoptosis. PDE5 inhibitors (PDE-Is) found application in cardiology, nephrology, urology, dermatology, oncology, and gynecology. Positive result of sildenafil treatment is closely connected with its immunomodulatory effects. Sildenafil influences angiogenesis, platelet activation, proliferation of regulatory T cells, and production of proinflammatory cytokines and autoantibodies. Sildenafil action in humans and animals appears to be different. Surprisingly, it also acts differently in males and females organisms. Although the immunomodulatory effects of PDE5 inhibitors appear to be promising, none of them reached the point of being tested in clinical trials. Data on the influence of selective PDE5-Is on the human immune system are limited. The main objective of this review is to discuss the immunomodulatory effects of sildenafil in both patients and experimental animals. This is the first review of the current state of knowledge about the effects of sildenafil on the immune system.