Agonists of Proteinase-Activated Receptor-2 Stimulate Upregulation of Intercellular Cell Adhesion Molecule-1 in Primary Human Keratinocytes via Activation of NF-kappa B

Abstract

Proteinase-activated receptor-2 (PAR2) belongs to a new G protein-coupled receptor subfamily that is activated by various serine proteases. Recent knowledge indicates that PAR2 is involved in cutaneous inflammation and immune response. PAR2 is highly expressed by human keratinocytes (KTC). The underlying mechanisms of PAR2-mediated KTC function and cutaneous immune response are, however, still incomplete. Therefore, we investigated the activation of important signaling cascades in primary human KTC after PAR2-stimulation using specific agonists. Moreover, we compared PAR2-immunoreactivity in the epidermis of inflammatory dermatoses and normal human skin. Electrophoretic mobility shift assays and morphological transduction studies revealed PAR2-induced activation and translocation of nuclear factor kappa B (NF-kappaB) in primary human KTC with a maximum after 1 h. Supershift analysis demonstrated acivation of the p50/p65 heterodimer complex. PAR2 agonists also induced upregulation of intercellular adhesion molecule-1 (ICAM-1) RNA, as shown by RT-PCR. Use of NF-kappaB inhibitors prevented upregulation of the cell adhesion molecule ICAM-1 in KTC indicating a direct role of NF-kappaB in PAR2-mediated upregulation of ICAM-1. Fluorescence-activated cell sorter analysis confirmed PAR2-induced and NF-kappaB-mediated upregulation of ICAM-1 protein after 13 h. Moreover, increased expression of PAR2 was detected in KTC of patients with atopic dermatitis suggesting a role of PAR2 in human skin inflammation. In conclusion, PAR2 induces upregulation of cell adhesion molecules such as ICAM-1 in primary human KTC via NF-kappaB activation, and is upregulated in KTC during cutaneous inflammation. Thus, PAR2 may play an important regulatory role of human KTC during inflammation and immune response.

Protease-activated Receptor-2 (PAR-2)-mediated Nf-κB Activation Suppresses Inflammation-associated Tumor Suppressor MicroRNAs in Oral Squamous Cell Carcinoma

“…Many pro-inflammatory mRNAs, including those encoding cytokines and chemokines, are regulated downstream of PAR-2 through activation of the transcription factor Nf-B (16,(22)(23)(24)(25). We have shown previously that the secreted serine proteinase KLK5 is overexpressed in OSCC (17).…”

“…PAR-2 regulation of pro-inflammatory mediators in both tumor cells and immune cells is effected principally through the Nf-B signaling pathway (16,(23)(24)(25). Downstream of PAR-2 signaling, phosphorylation of RelA by IKK␤ and nuclear translocation of RelA-containing Nf-B dimers activate transcription of an array of pro-inflammatory cytokines and chemokines such as IL8 (CXCL8).…”

TRP Channels and Pruritus

“…Of great clinical importance, in AD patients the dysregulation of PAR2 and the activating proteases were observed both in sensory fibers and in epidermal keratinocytes [72]. In addition, kallikrein activity was also increased in pruritic papular eruptions [73].…”

Insulin Modulates Protease-Activated Receptor 2 Signaling: Implications for the Innate Immune Response

“…Because leukocyte trafficking along intestinal venules depends on endothelial function and the expression by both leukocytes and the endothelium of adhesion molecules and because PAR 2 been shown to play a role in the upregulation of ICAMs in endothelial cells (22), we hypothesized that insulin would be able to affect PAR 2 -AP signaling in HMECs (23). To test this hypothesis, we evaluated the ability of insulin to modulate PAR 2 -triggered calcium signaling in these cells.…”