Acne inversa: evaluating antimicrobial peptides and proteins

Abstract

Background: Acne inversa is a chronic, suppurative relapsing inflammatory skin disease that primarily affects the axillae, perineum and inframammary regions. Evidence suggests that the innate immune system is involved in the pathogenesis of acne inversa.

Objective: To investigate the role of the innate immune system in acne inversa.

Methods: Skin biopsies were obtained from inflammatory skin lesions (n=17) and from non-lesional skin (intraindividual control, n=17) of patients with acne inversa. Additional skin lesions were taken from patients with chronic venous leg ulcers (interindividual control, n=5). Quantitative real-time reverse transcription-polymerase chain reaction was used to determine the mRNA levels of antimicrobial peptides and proteins (AMPs), including human β-defensin (hBD)-1, hBD-2 and hBD-3, LL-37 (cathelicidin) and Ribonuclease 7 (RNase 7). mRNA levels were also determined for inflammatory and anti-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-1 (MMP1), interleukin (IL)-1β, IL-6, IL-8 and IL-10.

Results: The mRNA levels of hBD-2, LL-37, IL-1β, IL-6, IL-8, IL-10 and MMP1 were significantly higher in acne inversa lesions compared to non-lesional skin (p<0.05). A significant positive correlation expression was observed between hBD-2 mRNA expression and LL-37 (ρ=0.53, p=0.03), and between hBD-2 and RNAse 7 (ρ=0.68, p=0.006). When compared to the chronic venous leg ulcer lesions, acne inversa lesions showed a significantly higher expression of RNase 7 mRNA, while IL-1 β, IL-6, IL-8, TNF-α and MMP1 mRNA expression was significantly higher in the chronic venous leg ulcer lesions (p<0.05).

Conclusion: The AMP, cytokine milieu and tissue proteases in acne inversa lesions differ significantly from non-lesional skin and chronic venous leg ulcers. The positively correlating up-regulation of AMPs in acne inversa indicates an important role of the innate immune system in the pathogenesis of this disorder.

Keywords: Antimicrobial peptides; Hidradenitis suppurativa; Human β-defensin; LL-37; Ribonuclease 7.

Fig. 1

Human β-defensin (hBD)-2 mRNA expression in acne inversa lesional skin and non-lesional skin. Significantly higher expression in lesional skin (p<0.01).

Fig. 2

LL-37 mRNA expression in acne inversa lesional skin and non-lesional skin. Significantly higher expression in lesional skin (p<0.01).