Cutaneous immunohistochemical expression of interleukin-23 receptor (IL-23R) in psoriasis and psoriatic arthritis patients: Relation to musculoskeletal ultrasound findings

Aim of the workTo assess the immunohistochemical expression of cutaneous interleukin-23 receptor (IL-23R) in psoriasis and psoriatic arthritis (PsA) patients and study its relation to musculoskeletal ultrasound (MSUS) findings.Patients and methodsThe study was conducted on 40 patients: 20 with PsA and 20 with psoriasis only. The psoriasis area severity index (PASI) was estimated. Synovitis was assessed by Power Doppler ultrasound and enthesitis by Glasgow Ultrasound Enthesitis Scoring System (GUESS).ResultsThe mean age of PsA and psoriasis only patients (49.9 ± 11.6 and 44.9 ± 13 years) and gender (12 males and 8 females each) were comparable. IL-23R expression in the epidermal keratinocytes and dermal inflammatory cells of PsA patients scored 5 in 40% and 4 in 45% respectively while in psoriasis only the highest frequency of cases (40%) scored 2 in both. In psoriasis only, dermal and epidermal IL-23R were significantly associated to effusion (5 ± 0 vs 2.2 ± 0.7 and 4 ± 0 vs 1.5 ± 0.5, p < 0.001 respectively) and synovitis (5 ± 0 vs 2.4 ± 1 and 4 ± 0 vs 1.7 ± 0.8, p < 0.001 respectively) (p < 0.001) and both significantly correlated with erosions (r = 0.64, p = 0.002 and r = 0.64, p = 0.003) and GUESS (r = 0.68, p = 0.001 and r = 0.61, p = 0.005). Dermal IL-23R was significantly associated with the PASI score in PsA patients (r = 0.59, p = 0.01). On regression, IL-23R significantly predicted PsA (epidermal: p = 0.001 and dermal: p = 0.018).ConclusionIL-23R is highly expressed in psoriatic skin and strongly associated with psoriatic skin, joints and entheses findings. MSUS is valuable in the detection of subclinical arthritis. Cutaneous IL-23R expression may refer to early joint affection and with MSUS may allow early prediction and management.