Proteinase-activated receptors (PARs) are a novel family of G-protein coupled receptors, of which PAR₂, has been implicated in inflammatory airways disease. Although fibroblasts are pathologically important in the airways, the pro-inflammatory role of PAR₂ in these cells currently remains unknown. Thus, we have assessed PAR expression and functionality in human primary bronchial fibroblasts (HPBF) before assessing PAR₂ mediated HPBF proliferation, cytokine production and adhesion molecule expression. RT-PCR and flow cytometry demonstrated that HPBF express hPAR₁, hPAR₂ and hPAR₃, but not hPAR₄. Intracellular calcium signalling in HPBF in response to PAR agonists showed that only hPAR₁ and hPAR₂ were functional receptors. Utilizing the MTT assay to assess HPBF proliferation, no PAR₂ agonist proteinases or selective PAR₂-activating peptides (PAR₂-APs) tested, stimulated HPBF proliferation, whilst thrombin was a HPBF growth factor. mRNA for IL-8 and G-CSF was upregulated following addition of SLIGKV-NH₂ when assessed by RT-PCR. However, no significant increase in G-CSF or IL-8 protein was detected. In contrast, trypsin, stimulated IL-8 and G-CSF release from HPBF in a time and dose dependent manner. Leupeptin and soya trypsin inhibitor (STI) both completely abrogated trypsin stimulated cytokine release, indicating a requirement for trypsin's proteolytic activity. Finally, both trypsin and SLIGKV-NH₂ stimulated a striking increase in VCAM-1 expression at 12 hrs post-treatment respectively, which declined thereafter. PAR₂ driven upregulation of VCAM-1 cell expression and the release of IL-8 and G-CSF release from bronchial fibroblasts may be important in promoting neutrophilic airways inflammation.