A th2 cytokine interleukin-31 signature in a case of sporadic lichen amyloidosis

Abstract

Lichen amyloidosis (LA), a variant form of primary localised cutaneous amyloidosis (PLCA), is a chronic itching skin disease, caused by the extracellular deposition of amyloid proteins in the dermis (1). This entity is clinically characterised by grouped hyperkeratotic papules with itchy lesions usually situated primarily on the shins. The upper back, forearms and thighs can also be involved. While the pathomechanism of PCLA still remains unclear, recent studies have identified in familial PLCA mutations in both the oncostatin M receptor (OSMR) gene, which encodes the OSMRβ (2) and in the interleukin (IL)-31RA gene (3), which encodes the IL-31 receptor α subunit. These 2 subunits constitute the functional receptor for IL-31, a recently discovered cytokine belonging to the IL-6 cytokine family (4). In combination with gp130, OSMRβ is a component shared with the receptor for OSM, another IL-6 family related cytokine. OSMRβ and IL-31RA are widely expressed in keratinocytes, fibroblasts and cutaneous nerves. Based on these new data it has been suggested that OSMRβ or IL-31RA mutants, when stimulated by their ligands OSM or IL-31, trigger signalling abnormalities leading to keratinocyte apoptosis and pruritus (5). Moreover, IL-31 is associated with itchy conditions and overexpression of this cytokine is observed in prurigo and atopic dermatitis (6). Whether expression of IL-31 and/or its receptor is altered in LA is still unknown. Here, we performed an analysis of the OSMR gene and cutaneous expression patterns of cytokines and anti-microbial peptides (AMP) in a 42-year-old woman with a sporadic case of LA.