Toll‐like receptor ( TLR )7 expression in mycosis fungoides and psoriasis: a case–control study

Summary Background Toll‐like receptors ( TLR s) have been implicated in various dermatological diseases. TLR agonists have the capacity to potently activate the innate immune cells of patients with advanced, refractory, cutaneous T‐cell lymphoma ( CTCL ). Aim To detect TLR 7 gene expression in mycosis fungoides ( MF ) (a neoplastic skin condition) and to compare it with psoriasis (an inflammatory skin condition) in an attempt to clarify the pathogenic role played by TLR 7 in both conditions. Methods This case–control study enrolled 28 patients with MF : 30 patients with psoriasis, and 30 age‐ and sex‐matched healthy controls ( HC s). A 4‐mm punch skin biopsy was obtained from lesional skin of patients and from normal skin of HC s for detection of TLR 7 gene expression using real‐time PCR . Results Mean TLR 7 level in patients with MF (0.4 ± 0.23) was significantly lower than in patients with psoriasis (1.49 ± 0.46) and in HC s (1.22 ± 0.44) ( P < 0.001), and mean TLR 7 level in patients with psoriasis was significantly higher than in HC s ( P < 0.03). Based on MF staging, 21.4% of patients had stage Ia, 28.6% had stage Ib, 28.6% had stage II a and 21.4% had stage II b disease. Comparing the TLR 7 levels in relation to MF staging revealed the lowest mean value was in stage II b and highest mean value in stage Ia, and this was significant ( P < 0.001). Conclusion Disturbed innate immunity might play a role in the pathogenesis of neoplastic and inflammatory skin conditions. TLR 7 could be useful as a prognostic factor in MF .