CXCL1 and varicose ulcer: In vitro analyses employing cell cultures, wildtype and mutant strains, and clinical isolates from venous ulcers and blood, revealed that P. aeruginosa elastase (LasB) degrades a range of pro-inflammatory cytokines (G-CSF, GM-CSF, IFN-γ, IL-1ra, IL-6, IL-12p40, IL-23, TNF-α) and chemokines (Gro-α, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β) in the extracellular milieu, without impacting cell morphology, transcription factor activation, or subsequent intracellular cytokine production.