Leptin and leptin receptors in psoriatic skin before and after PUVA: a possible marker of psoriasis severity

Background Psoriasis is a multifactorial disease in which genetic and inflammatory factors play an important role. Leptin has been shown to have proinflammmatory effects and to play a regulatory role in the T-helper cell response. Although recent studies support the relation of psoriasis with obesity and cardiovascular disease, the relation of psoriasis and leptin still remains controversial. Objective To estimate the tissue levels of leptin and leptin receptor (leptin R) mRNA in psoriatic lesions and to determine the effect of Psoralen Ultraviolet Rays (PUVA) on their levels. Patients and methods Twenty-one psoriatic patients and 15 age-matched, sex-matched and weight-matched normal individuals were recruited for this work. Skin biopsies were taken from psoriatic lesions before the initiation of PUVA therapy and at the end of 30 sessions as well as from the normal skin of controls for the detection of leptin by enzyme-linked immunosorbent assay and the detection of leptin R mRNA by reverse transcriptase PCR. Results Before PUVA therapy, leptin and leptin R mRNA were significantly higher in psoriatic tissue compared with the normal tissue of control individuals (Po0.0001). Their pretreatment values decreased significantly after therapy (Po0.0001 and P = 0.001, respectively). Pretreatment leptin and leptin R mRNA values correlated positively with the pretreatment psoriasis area and severity index score (P= 0.008 and 0.002, respectively). Conclusion We suggest that leptin plays a role in the pathogenesis of psoriasis and might be considered as a marker of severity in psoriasis. Moreover, the reduction in the tissue levels of leptin might be related to the efficacy of PUVA in the treatment of psoriasis.