J Cutan Pathol 2008 doi: 10.1111/j.1600-0560.2007.00968.x Blackwell Munksgaard. Printed in Singapore Copyright # Blackwell Munksgaard 2008 Journal of Cutaneous Pathology Distribution of Malassezia species in patients with psoriasis and healthy individuals in Tehran, Iran Background: Psoriasis is a non-contagious disorder that affects the skin as red scaly patches. Although the role of Malassezia species in the pathogenesis of psoriasis is still not fully understood, it is thought that these lipophilic yeasts might be a trigger factor in the exacerbation of psoriatic lesions. Methods: Using culture in a specific medium followed by the polymerase chain reaction-restriction fragment length polymorphism method, the presence of Malassezia species in the skin of 110 patients with psoriasis was compared with that in a control group of 123 healthy patients. Results: The recovery rate of Malassezia species from the skin of patients with psoriasis was significantly lower than that in the controls. In both psoriatic and healthy skin, Malassezia globosa was isolated as the predominant species. In psoriatic patients, the rate of colonization of Malassezia furfur and Malassezia restricta was almost twice that in the controls, whereas M. globosa was isolated more frequently from healthy individuals than from patients. Conclusions: Considering the higher lipase activity secretion by M. furfur in comparison with other Malassezia species, the enzymatic release of arachidonic acid and its metabolites by M. furfur may exacerbate the inflammatory and hyperproliferative changes observed in psoriasis. Zomorodian K, Mirhendi H, Tarazooie B, Zeraati H, Hallaji Z, Balighi K. Distribution of Malassezia species in patients with psoriasis and healthy individuals in Tehran, Iran. Kamiar Zomorodian 1 , Hosssien Mirhendi 2 , Bita Tarazooie 2 , Hojjat Zeraati 3 , Zahra Hallaji 3 and Kamran Balighi 1 1 Department of Medical Mycology & Parasitology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran and 2 Department of Medical Mycology & Parasitology and 3 Department of Biostatistics, Medical Sciences/University of Tehran, Tehran, Iran Prof. Kamiar Zomorodian, Department of Medical Mycology & Parasitology, School of Medicine, Shiraz University of Medical Sciences, Zand Boulevard, Shiraz, Fars 71345, Iran Tel: 98-711-2305884 ext. 3137 Fax: 98-711-2305291 e-mail: zomorodian@sums.ac.ir Accepted for publication November 26, 2007 Psoriasis is one of the oldest recorded skin diseases, whose etiology is unknown, but is now believed to be an immune-mediated condition. There are several factors that are thought to aggravate psoriasis, such as stress, excessive alcohol consumption and some cutaneous microflora such as Malassezia and Can- dida. 1–5 . Malassezia species are a part of the resident skin flora of humans and other warm-blooded vertebrates. 6 These yeasts are associated with various superficial diseases, including pityriasis versicolor, seborrheic dermatitis and folliculitis. 7,8 Development of psoriatic-like lesions in both humans and animals following exposure to Malassezia yeasts has previously been reported. 9,10 It has also been shown that the antifungal agent ketoconazole can potentially affect psoriasis directly by its antifungal action against Malassezia yeast 11 or indirectly by suppressing Malassezia- induced lymphocyte-mediated immune responses. 12 More recent studies have indicated that Malassezia yeasts cause exacerbation of psoriasis by triggering the release of cytokines, in particular interleukin-8, through a Toll-like receptor 2-mediated pathway; 13 upregulating transforming growth factor b1 and heat shock protein 70 expression in keratinocytes 14 and 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 C U P 0 9 6 8 Journal Name Manuscript No. B Dispatch: 20.12.07 Journal: CUP CE: Mohana Priya Author Received: No. of pages: 5 ME: Senthil