Serum LL-37 and inflammatory cytokines levels in psoriasis

Abstract

Background: Psoriasis (PsO) is a T-cell-associated inflammatory autoimmune dermatitis. Leucine leucine-37 (LL-37) is upregulated in PsO patients and correlated with the area and severity of PsO. However, the exact relation between LL-37 and T cell-associated inflammation is not well understood. It is very important to clarify the relationship between LL-37 and inflammatory response for clinical diagnosis and treatment of PsO. This study investigated the serum levels of LL-37 and inflammatory cytokines, as well as correlations between them in PsO patients, which aimed to provide new ideas for the diagnosis and treatment of PsO.

Methods: PsO patients (n = 50) and healthy volunteers (n = 33) were recruited in this study. Skin specimens were stained with hematoxylin and eosin (H&E). The serum levels of LL-37, T-helper type 1 (Th1, IFN-γ), T-helper type 17 (Th17, IL-17), T-helper type 22 (Th22, IL-22), and T-helper type 2 cytokines (Th2, IL-4) were assessed by enzyme-linked immunosorbent assay. Some of the patients were re-recruited after treatment to evaluate LL-37 and cytokines levels.

Results: Pathological changes were observed in PsO skin lesions. LL-37, IFN-γ, IL-17, and IL-22 serum levels were much higher in PsO patients than those in healthy volunteers (p < .001), and posttreatment reduction was observed in five patients. However, no remarkable difference in IL-4 level (p > .05) was found. LL-37 level was positively correlated with IFN-γ, IL-17, and IL-22 levels (p < .001) in PsO patients.

Conclusion: LL-37 expression was significantly associated with inflammatory response, which may provide us new ideas for diagnosing and monitoring disease activity of PsO.

Keywords: LL-37; inflammatory cytokines; psoriasis.

Figure 1

Representative images of H&E stained normal and psoriatic skin biopsies. Formalin‐fixed paraffin‐embedded sections were stained with H&E. Scale bar = 30 µm. H&E, hematoxylin and eosin.

Figure 2

Serum levels of LL‐37 (A) and inflammatory cytokines including IFN‐γ (B), IL‐17 (C), IL‐22 (D), and IL‐4 (E) in PsO patients (n = 50) and healthy volunteers (n = 33). Comparisons between the two groups were made using an unpaired t‐test, with error bars representing the mean ± SEM. ns, not significant, ***p < .001. LL‐37, leucine leucine‐37.

Figure 3

Correlations between serum levels of IFN‐γ (A), IL‐17 (B), IL‐22 (C), IL‐4 (D), and LL‐37 in PsO patients (n = 50). The Pearson's correlation test and linear regression were used to calculate the linear regression lines. Data are presented as mean ± SEM. ns, not significant, ***p < .001. LL‐37, leucine leucine‐37; r, correlation coefficient.

Figure 4

Comparison of serum levels of LL‐37 (A) and inflammatory cytokines including IFN‐γ (B), IL‐17 (C), and IL‐22 (D) in five psoriasis patients before and after treatment. Statistical significance was analyzed by paired t‐test. *p < .05, **p < .01. LL‐37, leucine leucine‐37; Post, posttreatment; Pre, pretreatment.