A prospective study examining the expression of STAT 1, 3, 6 in prurigo nodularis lesions with its immunopathogenic and therapeutic implications

Prurigo nodularis (PN) is a chronic dermatologic condition manifesting as multiple papulonodular lesions occurring on the background of intense pruritus. PN could be primary or secondary. The exact immune pathogenesis of PN is not yet clear, and multiple pathways are proposed with the JAK-STAT pathway rarely being investigated.In this study, our aim was to assess the role of Th cells in PN by comparing the expression of STAT 1, 3, and 6 in involved and normal skin of primary prurigo nodularis.A total of 49 clinico-histopathologically proven cases of primary prurigo nodularis were included. Two skin biopsies for each patient from lesional and non-lesional skin were stained with STAT 1, 3, and 6, and the nuclear staining pattern in the epidermis was graded as strong, moderate, weak, or none.Statistically significant expression of STAT 3 and STAT 6 staining was seen in the epidermis of the lesional skin as compared to non-lesional skin.Our study showed a marked dominance of STAT 3 and STAT 6 staining in the epidermis which signifies that the keratinocytes play an important role in PN and suggest that Th2, Th17, and Th22 cytokines mediate the tissue response in PN.