Interleukin-13 Receptor in Psoriatic Keratinocytes: Overexpression of the mRNA and Underexpression of the Protein

Although several cytokines and their receptors have been involved in the development of psoriasis, the etiology is still unknown. In this study we looked for genes possibly involved in the disease by the reverse transcription–polymerase chain reaction differential display technique in lesional and nonlesional skin biopsies from psoriatic patients. We found the mRNA of the α1 chain of the interleukin-13 receptor expressed differentially in psoriatic biopsies. By reverse transcription–polymerase chain reaction, we confirmed an overexpression of the α1 chain of the IL-13 receptor and α chain of the interleukin-4 receptor mRNA in lesional skin psoriatic biopsies, when compared with skin biopsies from healthy subjects (p<0.01). The nonlesional skin obtained from a region close to a lesional zone in psoriatic patients presented also an overexpression of these mRNA in 50% of the samples. Interleukin-13 and interleukin-4 were not detected either as mRNA or as the proteins in any of the biopsies from psoriatic patients or healthy subjects. A monoclonal antibody to the α1 chain of the interleukin-13 receptor detected the receptor in the epidermal keratinocytes of psoriatic patients and of healthy subjects; however, the positive antibody reaction was stronger in skin tissue from healthy subjects than in psoriatic lesional skin tissue (p