An Overview on the Role of Microbial Agents in Psoriasis

Background and Psoriasis is a chronic inflammatory skin disease characterized by lesions covered with silvery-white scabs of dead skin. This autoimmune disease occurs when the immune system sends out faulty signals that speed up the growth cycle of skin cells. Prevalence of psoriasis in world populations is about 0.5-4% depending on the regions. People with psoriasis have an increased incidence of depression, obesity, diabetes, hypertension, cardiovascular disease and cancer. The exact cause of psoriasis is unknown, however, recently the role of microbial agents in triggering or exacerbating psoriasis has been considered. The main objective of this study was an overview on the role of microbial agents in psoriasis. Published articles in PubMed/MEDLINE and Iranian databases between 1961 and 2011 were reviewed for the role of microbial agents in psoriasis. The results of these studies were carefully analyzed. Microbial agents, especially Streptococcus pyogenes, Staphylococcus aureus, Candida species, Malassezia species, Enterococcus faecalis and Pseudomonas aeruginosa can alter the process of disease via change in the skin characteristic of patients with psoriasis. According to this review, it is believed that microorganisms are very important in pathogenesis of psoriasis. Microorganisms can lead to exacerbation of psoriasis via monocytes and T cells activation by Superantigens and secretion of various toxins.