Decreased progranulin expression in Mycosis fungoides: a possible association with the high frequency of skin infections.

Progranulin (PGRN) is a multi-functional protein known to be involved in diverse biological processes, including tumourigenesis, anti-inflammation, and anti-infection. PGRN expression in sera or tissues is elevated in a variety of malignancies and is associated with poor prognosis. However, it remains to be determined whether PGRN is involved in Mycosis fungoides (MF). To investigate the roles of PGRN in MF. Serum PGRN levels were measured in patients with MF and normal controls by enzyme-linked immunosorbent assay. PGRN expression in MF and normal skin was examined by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Moreover, we analysed correlations between the expression levels of PGRN and antimicrobial peptides in lesional skin. PGRN levels were significantly lower in sera of MF patients than those of normal controls. PGRN mRNA levels in lesional skin of MF were also significantly decreased. Immunohistochemical staining revealed that PGRN was expressed in epidermal keratinocytes of normal controls, however, PGRN expression in epidermal keratinocytes was also weaker in MF skin. Furthermore, significant inverse correlations were identified between PGRN and antimicrobial peptide mRNA expression. These results suggest that low PGRN expression may contribute to the frequent occurrence of skin infections in patients with MF.