Role of Platelet-Activating Factor in the Pathogenesis of Chronic Spontaneous Urticaria

Abstract

Chronic spontaneous urticaria (CSU) is a debilitating condition characterized by mast cell activation. Platelet-activating factor (PAF) is produced by various immune cells, including mast cells, basophils, lymphocytes, and eosinophils, which play crucial roles in CSU pathogenesis. It induces mast cell degranulation, increases vascular permeability, and promotes the chemotaxis of inflammatory cells. These effects result in the release of inflammatory mediators, the development of edema, and the persistence of inflammation, which are key features of CSU. Notably, elevated PAF levels have been linked to heightened disease activity and resistance to antihistamine treatment in CSU patients. Despite these findings, the precise role of PAF in CSU pathogenesis remains unclear. Rupatadine, an antihistamine, and heat shock protein 10, a natural anti-inflammatory peptide that selectively inhibits PAF-induced mast cell degranulation, have demonstrated anti-PAF activity. Furthermore, with the molecular structure of the PAF receptor now identified, several experimental PAF receptor antagonists have been synthesized. However, there remains a significant need for the development of therapeutic options targeting PAF in CSU management.

Keywords: chronic spontaneous urticaria; degranulation; mast cells; platelet-activating factor.

Figure 1

Mast cell degranulation. Modified from a previous study [22].

Figure 2

Pathways of PAF synthesis and metabolism.

Figure 3

PAF-PAFR signaling.

Figure 4

Role of PAF in the pathogenesis of chronic spontaneous urticaria.