IL-17 Pathway Members as Potential Biomarkers of Effective Systemic Treatment and Cardiovascular Disease in Patients with Moderate-to-Severe Psoriasis

Abstract

Psoriasis is a chronic inflammatory condition associated with atherosclerotic cardiovascular disease (CVD). Systemic anti-psoriatic treatments mainly include methotrexate and biological therapies targeting TNF, IL-12/23 and IL-17A. We profiled plasma proteins from patients with moderate-to-severe psoriasis to explore potential biomarkers of effective systemic treatment and their relationship to CVD. We found that systemically well-treated patients (PASI < 3.0, n = 36) had lower circulating levels of IL-17 pathway proteins compared to untreated patients (PASI > 10, n = 23). Notably, IL-17C and PI3 were decreased with all four examined systemic treatment types. Furthermore, in patients without CVD, we observed strong correlations among IL-17C/PI3/PASI (r ≥ 0.82, p ≤ 1.5 × 10^-12) pairs or between IL-17A/PASI (r = 0.72, p = 9.3 × 10^-8). In patients with CVD, the IL-17A/PASI correlation was abolished (r = 0.2, p = 0.24) and the other correlations were decreased, e.g., IL-17C/PI3 (r = 0.61, p = 4.5 × 10^-5). Patients with moderate-to-severe psoriasis and CVD had lower levels of IL-17A compared to those without CVD (normalized protein expression [NPX] 2.02 vs. 2.55, p = 0.013), and lower IL-17A levels (NPX < 2.3) were associated with higher incidence of CVD (OR = 24.5, p = 0.0028, 95% CI 2.1-1425.1). As a result, in patients with moderate-to-severe psoriasis, we propose circulating IL-17C and PI3 as potential biomarkers of effective systemic anti-psoriatic treatment, and IL-17A as potential marker of CVD.

Keywords: IL-17A; IL-17C; Olink; PI3/elafin; cardiovascular disease; proteomics; psoriasis; psoriasis area and severity index.

Figure 1

Differentially expressed proteins (DEPs) in effective systemic treatment of psoriasis. (a) Proteins measured by Olink CVDII, CVDIII and Inflammation panels were compared between systemically well-treated (PASI < 3.0, n = 36) and systemically untreated (PASI > 10.0, n = 23) patients with results visualized by Volcano plot. LogFC are in Log2 scale, and adjusted p-values < 0.05 are colored and labeled in blue. (b) Gene set enrichment was performed using STRING enrichment plugin against Gene Ontology, KEGG and Reactome pathway databases. Enrichment of IL-17 signaling pathway was detected, which contained IL-17C, CCL20, TNF and MCP-3/CCL7. (c) Protein-protein interaction network analysis of DEPs was performed and visualized by Cytoscape with STRING plugin. (d) Heatmap showing median NPX values of DEPs between PASI > 10.0 no treatment (n = 23) and PASI < 3.0 with treatment groups (n = 36).

Figure 2

Differentially expressed proteins (DEPs) between various types of systemic treatment of psoriasis and no treatment. Normalized protein expressions of Olink CVDII, CVDIII and Inflammation panels were compared separately between various types of effective antipsoriatic treatment (PASI < 3.0) and no treatment (PASI > 10.0, n = 23), and visualized by Volcano plots. (a) Methotrexate (n = 11); (b) Ustekinumab (IL-12/23 antibody, n = 5); (c) Secukinumab (IL-17 antibody, n = 6); (d) Adalimumab (TNF antibody, n = 8). LogFC are in Log2 scale, and adjusted p-values < 0.05 are colored and labeled in blue. (e) Venn diagram of DEPs resulting from various types of treatment show shared PI3 and IL-17C protein changes. (f) Gene set enrichment for all 11 DEPs from each of the treatment types identified enrichment of the IL-17 signaling pathway.

Figure 3

Correlation matrix of selected differentially expressed proteins (DEPs) and PASI for all patients (n = 84). (a) Correlation matrix heatmap shows correlations between selected DEPs and PASI for all patients (n = 84); (b) Pearson correlation scatter plots between selected DEPs proteins and PASI for all patients (n = 84), and correlation between PI3 and IL-17C. Pearson correlation coefficients R are shown with associated p-values, and y-axis shows protein NPX values. (c) Pearson correlation scatter plots before (n = 84, left panel) and after (n = 77, n = 73, and n = 72, respectively, right panel) excluding the patients with paradoxically elevated levels of targeted cytokines receiving anti-IL-17A (n = 7), anti-IL-12/23 (n = 11), and anti-TNF (n = 12), respectively, from the analyses.

Figure 4

Correlations of selected differentially expressed proteins (DEPs) and PASI for patients with (n = 39) or without CVD (n = 45). (a) Correlation matrix heatmap shows correlations between selected DEPs and PASI for patients without CVD (n = 45); (b) Correlation matrix heatmap shows correlations between selected DEPs and PASI for patients with CVD (n = 39); (c) Pearson correlation scatter plots between selected DEPs and PASI for patients with psoriasis and CVD or without CVD. Pearson correlation coefficients R are shown with associated p-values, and y-axis shows protein NPX values.

Figure 4

Correlations of selected differentially expressed proteins (DEPs) and PASI for patients with (n = 39) or without CVD (n = 45). (a) Correlation matrix heatmap shows correlations between selected DEPs and PASI for patients without CVD (n = 45); (b) Correlation matrix heatmap shows correlations between selected DEPs and PASI for patients with CVD (n = 39); (c) Pearson correlation scatter plots between selected DEPs and PASI for patients with psoriasis and CVD or without CVD. Pearson correlation coefficients R are shown with associated p-values, and y-axis shows protein NPX values.

Figure 5

Comparison of IL-17A, IL-17C and PI3 protein levels in patients stratified by CVD and psoriasis severity. Boxplot comparison of IL-17A, IL-17C and PI3 protein levels in patients with CVD (n = 39) and without CVD (n = 45), y-axis shows protein NPX values. A t-test was carried out and resulting p-values are shown. In patients with PASI > 10 the mean normalized protein expression (NPX) of IL-17A was 2.55 in subjects without CVD, compared to 2.02 in those with CVD (p = 0.013). Fisher’s exact test showed that an IL-17A NPX value below 2.3 was associated with higher incidence of CVD for patients with PASI > 10 (horizontal dotted line). In patients with PASI ≤ 10, the mean IL-17C NPX was 2.82 in patients without CVD compared to 3.27 in patients with CVD (p = 0.051).