Functional angiotensin and bradykinin receptors are expressed on primary human mast cells

Abstract

Abstract Purpose The role of mast cells (MCs) has traditionally been recognized as an effector cell for IgE-mediated allergic diseases, involving ~20% of USA citizens. However, everyone has MCs, indicating their involvement in biologic and pathobiologic conditions beyond allergy. Angiotensin converting enzyme inhibitors (ACEI) and angiotensin II type 1 receptor (AT1R) blockers are used to treat cardiovascular disorders such as hypertension, while a bradykinin type 2 receptor (B2R) inhibitor is used to treat attacks of hereditary angioedema. We examined the expression and biological function of AT1R, B2R and B1R on primary human MCs. Methods MCs were dispersed from fresh surgical human skin obtained from CHTN, and placed into culture with SCF (100 ng/ml) for 4–8 weeks. FACS analysis, western blotting, qRT-PCR, degranulation (β-hexosaminidase release), cytokine/chemokine secretion of IL-6, IL-8 and CCL5, nitric oxide (NO) production (DAF-AM diacetate) were measured. Results FACS analysis and western blotting showed the AT1R and B2R are expressed on MCs. Angiotensin II (0.1–10 μM) and bradykinin (BK, 0.1–2 μM) stimulated MCs to release cytokines (1–4 ng/ml) which was inhibited by specific inhibitors. BK also stimulated the production of NO. Both the B2R and B1R are up-regulated by TNFα (10 ng/ml for 3 days), leading to enhanced activation of MCs by BK (1 μM) and desArg-LysBK (1 μM). Exposure of MCs to angiotensin II (2 μM), angiotensin (1–7)(10 μM) or ACEI (ramipril 1 μM) also enhanced cytokine secretion triggered by low concentration of BK (0.03–0.25 μM). Conclusion These findings suggest functional interactions of AT1R, B2R, ACE and Mas on human MCs, providing novel roles for MCs in cardiovascular, inflammatory and allergic disorders.