Cytokine gene expression in the tunica albuginea of patients with Peyronie’s disease. Pilot study with a control group

Introduction and objective: Cytokines may be involved in the pathogenesis of Peyronie’s disease (PD). In this case, biological drugs, acting on specific cytokines, could be adopted in the pharmacological treatment of the disease.
Materials and methods: Twenty PD patients and 8 patients affected by congenital recurvatum penis (control group) who underwent corporoplasty were enrolled in the study. Histological examination and measurement by Real Time PCR of the expression of the encoding genes for IL-2, IL-4, IL-6, IL-10, IL-13, TGF-β, TNF-α and IFN-γ were performed on the removed tunica albuginea (TA). For the normalization of data GAPDH (glucerldehyde-3fosfatehydrogenase) and GUSB (β-glucuronidase), housekeeping genes were used. The analysis of the data was performed using the comparative method 
of ΔCt. The results were reported with the Fold of induction (FOI) method.
Results: The histological exams of TA showed only fibrous tissue without cavernous tissue. The analysis of gene expression of IL-6, IL-10, IFN-γ and TGF-β1 showed in all samples very low levels. The levels were lower in PD patients although the differences were not statistically significant. An exception was represented by TGF-β that showed a higher level in PD patients, although not statistically significant. The expression of IL-4, IL-13 and TNF-α was undetectable.
Conclusions: The expressions of cytokines in TA of PD patients compared to those of the controls do not show any significant difference. A bias of our study is that the groups were not age-matched. This is a bias already present in similar experiences and due to the different pathogenesis of the diseases. Cytokines promoting inflammation resulted undetectable and do not seem to be involved in PD pathogenesis. The higher level of TGF-β, a pro-fibrotic cytokine, detected in PD could explain the presence of fibrotic tissue. Presently, there is no data suggesting a possible role of biological drugs in PD.