The In Vitro Inhibitory Effect of Sivelestat on Elastase Induced Collagen and Metallopeptidase Expression in Equine Endometrium

SIMPLE SUMMARY: The protease elastase found in neutrophil extracellular traps appears to be associated with equine endometrial fibrosis by its stimulatory effect on extracellular matrix (ECM) components, leading to an increase in collagen relative abundance. Metallopeptidases (MMP-2 and -9) are enzymes involved in ECM remodeling. The modulation of elastase-induced deleterious effect on ECM and MMPs could be important for the prevention of fibrosis development. The selective inhibitor sivelestat is known to inhibit elastase activity. Our results showed that sivelestat inhibits the production of elastase-induced collagen in vitro by equine endometrial explants, and that MMP-2 and MMP-9 might be implicated in endometrium fibrotic response to elastase. By inhibiting elastase, it would be possible to prevent fibrosis development in mare’s endometrium. ABSTRACT: Neutrophil extracellular traps (NETs) fight endometritis, and elastase (ELA), a protease found in NETs, might induce collagen type I (COL1) accumulation in equine endometrium. Metallopeptidases (MMPs) are involved in extracellular matrix balance. The aim was to evaluate the effects of ELA and sivelestat (selective elastase inhibitor) on MMP-2 and MMP-9 expression and gelatinolytic activity, as well as the potential inhibitory effect of sivelestat on ELA-induced COL1 in equine endometrium. Endometrial explants from follicular (FP) and mid-luteal (MLP) phases were treated for 24 or 48 h with ELA, sivelestat, and their combination. Transcripts of COL1A2, MMP2, and MMP9 were evaluated by qPCR; COL1 protein relative abundance by Western blot, and MMP-2 and MMP-9 gelatinolytic activity by zymography. In response to ELA treatment, there was an increase in MMP2 mRNA transcription (24 h) in active MMP-2 (48 h), both in FP, and in MMP9 transcripts in FP (48 h) and MLP (24 h) (p < 0.05). Sivelestat inhibited ELA-induced COL1A2 transcripts in FP (24 h) and MLP (24 h, 48 h) (p < 0.05). The sivelestat inhibitory effect was detected in MMP9 transcripts in FP at 48 h (p < 0.05), but proteases activity was unchanged. Thus, MMP-2 and MMP-9 might be implicated in endometrium fibrotic response to ELA. In mare endometrium, sivelestat may decrease ELA-induced COL1 deposition and hinder endometrosis development.