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

Abstract

Background: Several workers have found that Malassezia are capable of suppressing cytokine release and downregulating the phagocytic function of monocytes. But lipid-depleted Malassezia furfur (M. furfur) extracts have also been shown to induce increased production of TNF-alpha, IL-6 and IL-1beta in monocytes. We thought that the detergents in shampoos or soaps could change the composition of the lipid in the M. furfur cell wall.

Objective: We studied whether detergents affect the morphology of M. furfur and if the inflammatory cytokine profiles change in the monocytes treated with detergent-treated M. furfur.

Methods: Commonly used detergents such as sodium lauryl sulfate, ammonium lauryl sulfate and tween-80 were respectively added to the modified Leeming-Notman's media. M. furfur was cultivated in each media (detergent-added or untreated). Thereafter, the surface morphology of the yeast was evaluated by scanning and transmission electron microscopy. The cytokine profiles of monocytes, which were treated by M. furfur with or without detergents, were also evaluated.

Results: The detergent-treated M. furfur were similar to the lipid-extracted form of M. furfur on the electron microscopic study, with a recessed, withered surface and with thinner and rather electron transparent cell walls than the detergent-untreated M. furfur. The levels of TNF-alpha were higher in monocytes treated with detergent-treated Malassezia than that in the monocytes treated with the detergent-untreated Malassezia (p<0.05).

Conclusion: According to the findings in this study, it could be inferred that the detergents in shampoos or soaps affect the lipid layers of the Malassezia cell wall and these lipid-extracted Malassezia induce or aggravate some inflammatory conditions. But to correlate the relationship between detergents and Malassezia-associated diseases, in vivo experiments that will focus on short-term contact with detergents in real life conditions should be done.

Keywords: Detergent; Malassezia furfur.

Fig. 1

Flow chart of this study.

Fig. 2

Scanning and transmission electron microscopic findings of the detergent-untreated and tween-80 treated M. furfur. (A) Scanning EM of the detergent-untreated M. furfur shows a smooth, round surface with fimbriae. (B) The transmission EM shows outer lamellar layers (arrowhead), an inner plasma membrane (arrow) and intermediate multiple layers. (C) M. furfur cultured in the tween-80 added media shows recessed and withered irregular surfaces on the scanning EM. (D) As compared with the untreated M. furfur, the cell wall of the M. furfur cultured in the tween-80 added media is much thinner and more transparent on the transmission EM.

Fig. 3

Morphological alteration of the ALS-treated M. furfur. (A) Transmission electron microscopic findings of the M. furfur cultured in regular media. (B) The transmission electron microscopic findings of the M. furfur cultured in 0.2% ALS added media. As compared with the untreated M. furfur, the cell wall of the M. furfur cultured in 0.2% ALS added media is much thinner and more transparent.

Fig. 4

The effect of detergent on the M. furfur-induced TNF-α production of monocytes (as detemined by ELISA). As compared with the M. furfur from the non-treated media, the detergent-treated M. furfur induced greater TNF-α in the monocytes. MLNM: modified Leeming-Notman media, SLS: sodium lauryl sulfate, ALS: ammonium lauryl sulfate, LPS: lipopolysaccharide.