Alternative activation of hedgehog pathway induced by ultraviolet B radiation: preliminary study.

BACKGROUND: There is still much ambiguity in studies of Sonic hedgehog (Shh) pathways and its dysregulation. Some studies concerning the role of the Shh pathway in basal cell carcinoma (BCC) have been conducted, but there is a lack of studies about Shh pathway dysregulation under the influence of ultraviolet (UV)B radiation. AIM: To evaluate skin expression of Shh, Ptch1, Ptch2, Smo and Gli1 proteins in BCCs with and without the influence of UVB radiation. METHODS: In total, 34 healthy controls (HCs) and 42 patients with nodular BCC were recruited into the study. Patients were divided into five groups (A-E), depending on UVB dose received and BCC status. In all skin specimens, expression of Shh, Ptch1, Ptch2, Smo and Gli1 protein was evaluated. RESULTS: Comparing the BCC group with the HC group, there was significantly higher expression of Shh, Ptch1, Ptch2, Smo and Gli1 proteins. Expression of Ptch2, Smo and Gli1 was increased in response to UVB doses of 3 MED (minimal erythema dose), whereas expression of Ptch1 and Shh was unaffected. CONCLUSION: The lack of change in expression of Shh and Ptch1 after exposure to UVB suggests that the Shh pathway may be activated through a noncanonical pathway under the influence of strong UVB doses.

Mast cells generate cysteinyl leukotrienes and interferon-beta as well as evince impaired IgE-dependent degranulation upon TLR7 engagement.

Mast cells are numerous at anatomical sites close to external environment, virtually at the portals of infection. A few data indicated that these cells express cytoplasmic Toll-like receptors (TLRs) recognizing virus-derived molecules. Accordingly, mast cells could participate in anti-viral defense or/and in viral-related diseases. However, data concerning the influence of viruses on mast cell activity are limited. Thus, the aim of our study was to determine mast cell response to TLR7 ligand, i.e. resiquimod (R848), a synthetic mimic of viral ssRNA. Since mast cells play a central role in allergic reactions the effect of TLR7 agonist was also investigated on FcepsilonRI-dependent mast cell response. Experiments were carried out in vitro on freshly isolated fully mature rat peritoneal mast cells. Mast cells exhibit constitutive TLR7 molecule expression and its up-regulation after the agonist challenge. TLR7-mediated mast cell stimulation resulted in cysteinyl leukotriene (cysLT) and interferon (IFN)-beta synthesis, whereas no histamine and CXCL8 secretion was stated. Moreover, mast cell priming with TLR7 ligand caused the reduction in anti-IgE-induced histamine release. The results suggest that ssRNA viruses could directly activate mast cells to alter their phenotype and to release of potent proinflammatory mediators or indirectly modulate IgE-dependent allergic processes.