Dermal distribution of hyaluronan in psoriatic arthritis; coexistence of CD44, MMP3 and MMP9.

Psoriatic arthritis is a chronic systemic disease in which patients develop persistent inflammation of the skin and joints, leading to disability and joint damage. The extracellular component hyaluronan (HA) plays an important role in regulatory processes such as inflammation, wound healing and tumour progression. At any site of inflammation HA can be depolymerized to low-molecular weight fragments, which, in turn, induce an array of inflammatory mediators that can lead to chronic inflammation. This study describes the serum concentration and dermal distribution of HA, its receptor CD44 and the metalloproteinases 3 and 9 in skin biopsies from patients with different types of psoriatic arthritis. Fifty-one patients with psoriatic arthritis were included in the study and classified as oligo- or poly-arthritic PsA with and without treatment. Biopsies were obtained from both involved and non-involved skin and compared with biopsies from healthy individuals. Serum HA was analysed for estimation of the total turnover of HA. The main findings were an overall redistribution of HA in both involved and non-involved psoriatic skin and an epidermal imbalance between HA and CD44. The structurally and functionally important basement membrane zone was found to be disintegrated and devoid of HA irrespective of the type of articular involvement, treatment or skin affection.