The Effects of Malassezia Yeasts on Cytokine Production by Human Keratinocytes

Abstract

Yeasts of Malassezia, members of the microbiologic flora of the skin, cause pityriasis versicolor and have also been implicated in the pathogenesis of other superficial dermatoses; the most important ones are seborrheic dermatitis, folliculitis, and atopic dermatitis. The mechanisms by which the yeasts cause these dermatoseş however, are not yet clear, and there have been no studies on the interaction between fungi and keratinocytes, especially the effects of fungi on the production of cytokines by human keratinocytes. Recently, the genus Malassezia has been expanded to seven species based on molecular data. In this study, we estimated the effects of Malassezia yeasts on cytokine (interleukins 1beta, 6, and 8, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) production by human keratinocytes in order to examine whether the pathogenicity of the respective Malassezia yeasts is different from each other and to elucidate the mechanism by which Malassezia yeasts cause the dermatoses with different clinical and pathologic manifestations. Variable levels of interleukin 6 and 8, and tumor necrosis factor-alpha in the supernatants in response to Malassezia yeasts (except M. furfur) increased from 1 to 24 h co-culture, but the monocyte chemotactic protein-1 was undetectable. Furthermore, cytokine levels in the supernatants were undetectable 1-24 h after the keratinocytes were harvested with only supernatants of Malassezia. These results indicate that Malassezia stimulates cytokine production by keratinocytes, the cytokine production needs the presence of Malassezia, and there are differences in ability to induce cytokine production by human keratinocytes among Malassezia yeasts. These differences may reflect the different inflammatory responses in Malassezia-associated dermatoses, resulting in different clinical and pathologic manifestations.

Dermatite seborreica

“…For example, when IL-8 is produced, neutrophils are attracted, manifested clinically in the form of Malassezia folliculitis; likewise, lack of production of monocyte chemotactic protein-1 (MCP-1) clinically determines SD. 84 No increase was found in the production of anti-Malassezia antibodies (IgM and IgG) in patients with SD. This observation was significant in patients with atopic dermatitis and suggests that there is no anti-Malassezia spp.…”

The Effect of Detergents on the Morphology and Immunomodulatory Activity ofMalassezia furfur

“…Several researchers have insisted that Malassezia is able to upregulate phagocytic cells and thus this provides enhanced protection against bacterial and tumor cell challenges in animals 1,19,20 . Yet other studies have demonstrated that…”

“…Malassezia is also capable of downregulating the immune system 7,19 . When various preparations of Malassezia were co-incubated with monocytes, the levels of IL-1β released by the monocytes were significantly lower than those of the negative control 17 .…”

Fungi on the Skin: Dermatophytes and Malassezia

“…A Malassezia lipase has been shown to split triglycerides into irritant fatty acids that can induce scaling (Troller 1971;McGrath and Murphy 1991;Parry and Sharpe 1998) or can release arachidonic acid, which is involved in the inflammation of skin (Faergemann and Fredriksson 1979;Binder and Jonelis 1983;Riciputo et al 1996). Further research may reveal to what extent the D/SD-promoting role of Malassezia is mediated by the immune system, by the enzymatic activity of the fungus, or by additional features such as secondary metabolites (Faergemann and Fredriksson 1979;Hay and GrahamBrown 1997;Watanabe et al 2001).…”