Soluble Mediators Potentially Involved in Pruritus Associated to Cutaneous T-Cell Lymphomas and Mastocytosis: A Cross-Sectional Study

Pruritus is a major distressing symptom, common in inflammatory diseases, like Cutaneous T-Cell Lymphoma (CTCL) and mastocytosis. We aimed to study the involvement of some molecules, namely, cytokines, neuromediators, endothelial adhesion molecules and angiogenic factors, in the severity of pruritus associated to CTCL and mastocytosis. CTCL - Mycosis Fungoides (MF, n=17) and Sézary syndrome (SS, n=10) and mastocytosis patients (n=17) were evaluated. Interleukin (IL)-8, IL-31, Vascular Endothelial Growth Factor (VEGF), E-selectin, serotonin and C-reactive protein (CRP) levels, were assessed; tryptase was measured in mastocytosis. Pruritus severity was assessed, using a Visual Analogue Scale (VAS). Compared to controls (n=29), CTCL patients presented higher CRP and IL-31. SS patients had higher IL-31, E-selectin and CRP than MF patients and controls. Itch correlated with IL- 31 and E-selectin, when considering all CTCL patients; in SS, itch correlated with E-selectin. Advanced CTCL stages revealed higher IL-31, E-selectin and CRP than early stages, and controls; itch intensity correlated with IL-31 and E-selectin, in advanced stages. Mastocytosis showed higher serotonin and VEGF, compared to controls, and itch intensity correlated with tryptase. Data suggest that in mastocytosis, serotonin is an important biomarker and that tryptase levels reflect itch intensity; IL-31 and E-selectin appear to be more important mediators in CTCL and strongly correlated with itch severity. The different involvement of studied mediators, probably due to different immune responses, suggests that different mechanisms underlie these diseases and may lead to different itch mechanisms.