Host/ Malassezia Interaction: A Quantitative, Non-Invasive Method Profiling Oxylipin Production Associates Human Skin Eicosanoids with Malassezia

Abstract

Malassezia are common components of human skin, and as the dominant human skin eukaryotic microbe, they take part in complex microbe-host interactions. Other phylogenetically related fungi (including within Ustilagomycotina) communicate with their plant host through bioactive oxygenated polyunsaturated fatty acids, generally known as oxylipins, by regulating the plant immune system to increase their virulence. Oxylipins are similar in structure and function to human eicosanoids, which modulate the human immune system. This study reports the development of a highly sensitive mass-spectrometry-based method to capture and quantify bioactive oxygenated polyunsaturated fatty acids from the human skin surface and in vitro Malassezia cultures. It confirms that Malassezia are capable of synthesizing eicosanoid-like lipid mediators in vitro in a species dependent manner, many of which are found on human skin. This method enables sensitive identification and quantification of bioactive lipid mediators from human skin that may be derived from metabolic pathways shared between skin and its microbial residents. This enables better cross-disciplinary and detailed studies to dissect the interaction between Malassezia and human skin, and to identify potential intervention points to promote or abrogate inflammation and to improve human skin health.

Keywords: Malassezia; eicosanoids; lipidomics; mycobiome; non-invasive; oxylipins; skin.

Figure 1

The results using scatter dot plots showing the median (bold horizontal line), interquartile range (box), and lipid mediator concentrations in the Y-axis across four different pre-selected time intervals (0, 24, 48, and 72 h without washing). The results are the mean ± S.E. *, p ≤ 0.05 **, p ≤ 0.01, *** p ≤ 0.001, and **** p ≤ 0.0001. h refers to hours.

Figure 2

Heat map clustering and orthogonal partial least square discriminant analysis (OPLS-DA) comparing lipid mediator concentrations produced on skin before and after washing. (A) Heat map clustering analysis using Ward’s algorithm of skin lipid mediator concentrations that differed significantly between pre- and post-wash conditions, based on one-way ANOVA tests. The color scale from −6 to 6 represents the z-score, with positive z-score values in red indicating increased lipid mediator concentrations and negative z-score values in blue reflecting decreased lipid mediator concentrations before and after washing. (B) OPLS-DA comparing lipid mediator concentrations before and after washing.

Figure 3

Comparative quantification of lipid mediators in the cheek samples by targeted lipidomics. (A) Pie charts showing total lipid mediators detected on the skin of individual subjects and their proportional distribution. The percentage of lipid mediators is only indicated for species that are represented by at least 10%. (B) Stacked bar charts show concentrations of lipid mediators that were quantified on the indicated 6 consecutive days, grouped by subjects. (C) sPLS-DA comparing lipid mediator concentrations between different subjects. 95% confidence region is shown for each sample group. Only the most distinct subjects are labeled.

Figure 4

Malassezia are capable of producing lipid mediators that can be detected on human skin. (A) Heat map clustering analysis using Ward’s algorithm of skin lipid mediator concentration averages from triplicate data sets that differed significantly between three different Malassezia species, based on one-way ANOVA tests. (B) OPLS-DA comparing lipid mediator concentrations between three different Malassezia species. (C) Venn diagram of overlapping lipid mediators between human skin and Malassezia. Underlined lipid mediators were detected in psoriatic skin (38). Total 54 different lipid mediator species, of which 25 are overlapping between human skin and Malassezia.