Lipidomic Analysis Reveals Specific Differences between Fibroblast and Keratinocyte Ceramide Profile of Patients with Psoriasis Vulgaris

Abstract

Ceramides are important lipid metabolites for primal skin functions. There is increasing evidence that alteration of the profile and metabolism of ceramides is associated with skin diseases, such as psoriasis vulgaris. Most studies have reported alteration in ceramide content in the stratum corneum, but these have been scarcely reported for other skin layers. In the present work, we aimed to explore changes in the ceramide profile of fibroblasts and keratinocytes in patients with psoriasis vulgaris and healthy subjects. Using the reversed-phase liquid chromatography-quadrupole-time-of-flight-tandem-mass spectrometry (RPLC-QTOF-MS/MS) platform, we identified ceramide containing non-hydroxy fatty acid ([N]), α-hydroxy fatty acid ([A]), and esterified ω-hydroxy fatty acid ([EO]) and 3 sphingoid bases, dihydrosphingosine ([DS]), sphingosine ([S]), and phytosphingosine ([P]). We found that in the keratinocytes of patients with psoriasis, CER[NS], CER[NP], CER[AS], CER[ADS], CER[AP] and CER[EOS] tended to be expressed at higher relative levels, whereas CER[NDS] tended to be expressed with lower levels than in healthy subjects. In the case of fibroblasts, significant differences were observed, mainly in the three ceramide classes (CER[AS], CER[ADS] and CER[EOS]), which were expressed at significantly higher levels in patients with psoriasis. The most significant alteration in the fibroblasts involved elevated levels of CER[EOS] that contained ester-linked fatty acids. Our findings provide insights into the ceramide profile in the dermis and epidermis of patients with psoriasis and contribute for the research in this field, focusing on the role of keratinocyte-fibroblast crosstalk in the development of psoriasis vulgaris.

Keywords: ceramides; fibroblasts; keratinocytes; lipidomics; psoriasis vulgaris; skin.

Figure 1

Major subclasses of ceramides present in epidermis.

Figure 2

The proportions of ceramide families in the keratinocytes (A) and fibroblasts (B) of healthy subjects; (non-hydroxy fatty acid [N], α-hydroxy fatty acid [A], and esterified ω-hydroxy fatty acid [EO], dihydrosphingosine [DS], sphingosine [S], and phytosphingosine [P]).

Figure 3

Total amount of ceramides in the keratinocytes (A) and fibroblasts (C) and relative content of each ceramide class in the keratinocytes (B) and fibroblasts (D) of healthy subjects and patients with psoriasis vulgaris (Ps); (values are mean ± SD *** p < 0.001; ** p < 0.01); (non-hydroxy fatty acid [N], α-hydroxy fatty acid [A], and esterified ω-hydroxy fatty acid [EO], dihydrosphingosine [DS], sphingosine [S], and phytosphingosine [P], internal standard [ISTD]).

Figure 4

Principal component analysis (PCA) (left panels) and partial least square discriminant analysis (PLS-DA) (right panels) in a two-dimensional score plot of the relative abundance of ceramide species determined by RPLC-QTOF-MS in keratinocytes (A,B) and fibroblasts (C,D) of healthy subjects and patients with psoriasis vulgaris (Ps).

Figure 5

Two-dimensional hierarchical clustering heat map of the 20 CERs selected according to the VIP list in the keratinocytes (A) and fibroblasts (B). Relative abundance levels are indicated on the colour scale, with numbers indicating the fold difference from the overall average. The clustering of the sample groups is represented by the dendrogram at the top. The clustering of individual CER species with regard to their similarity in the change of relative abundance is represented by the dendrogram on the left.