Quantitative mRNA Analysis of IL-1 Gene System in Human Testis

Identification of IL-18RAP mRNA truncated splice variants in human testis and the other human tissues

IL-18 is a pleiotropic cytokine involved in the regulation of both innate and adaptive immunity. It plays a key role in the autoimmune, inflammatory and infectious diseases. IL-18 acts via a receptor complex that closely resembles that of IL-1, consisting of a ligand binding protein, IL-18Ralpha, and an accessory protein, IL-18RAP (IL-18Rbeta). IL-18RAP is essential for IL-18 signal transduction and ligand binding affinity to IL-18Ralpha receptor chain. mRNA of gene coding for IL-18RAP in human testicular tissue and the nucleotide sequence of splice variants was carefully examined. We have found for the first time ever, IL-18RAP mRNA in studied tissue samples of physiological testis. Using the RT-PCR technique, the whole coding sequence of this gene was amplified. An alternative splicing of mRNA for IL-18RAP was then discovered and subsequently confirmed by cDNA sequencing. The putative amino acid content was predicted and a computer modeling was performed. It might be hypothesized that the truncated forms of IL-18RAP can be involved in the complex mechanism of IL-18 activity regulation.

Interleukin-1 superfamily genes expression in normal or impaired human spermatogenesis

Interleukin-1 (IL-1) is a pleiotropic cytokine that may play a role in contributing to the specific immune environment of mammalian testis and in regulating cell differentiation. We have determined the transcription activity of the IL-1 gene family (using real-time polymerase chain reaction (PCR)) in two main functional testicular compartments (interstitial and intratubular ones), and in tissue homogenates obtained from patients with fertility disorders (spermatogenic arrest and testicular tumors). We observed the prominent expression of gene coding for IL-1 receptor antagonist (IL-1RA) in a purified fraction of gametogenic cells (normal gonad). Caspase-1 (ICE - IL-1beta-converting enzyme) was highly expressed (on mRNA level) in interstitial compartments as well in testicular tumors (immune enhancement?). In addition we found, that the activity of IL-1RA gene decreased along spermatogenic alteration in an inversely related manner with IL-1alpha (from normal gonad through spermatogenic arrest to Sertoli cell only syndrome). Therefore, the quotient value of IL-1alpha/IL-1RA could potentially serve as the diagnostic molecular probe for spermatogenesis assessment. The precise level of mRNA for IL-1-IL-18 cytokines and their receptors, and specifically of the receptor antagonist in immune privileged gonad, could be one of the main factors responsible for maintaining testicular homeostasis, thus enabling generation of the mature spermatozoa.