TIR8 receptor expression in bovine tissues

The TIR8 receptor (also called SIGIRR) is an orphan member of the TIR superfamily. Its function is still elusive, but it is believed to trigger a negative pathway of regulation of the Toll-like/IL-1 receptor system, crucial for modulating inflammation in gastrointestinal (GI) tract and in other tissues (lung and kidney). The expression pattern of TIR8 in bovine tissues is unknown. Given the importance of GI diseases in cattle, the aim of this investigation was to study the distribution of TIR8 in a wide panel of non-pathologic tissues and organs. TIR8 expression was assessed by Northern blot analysis and further confirmed and comparatively quantified by qualitative and quantitative (Real-Time) PCR. The possible presence of tissue-specific isoforms was determined by Western blot immunodetection, using an anti-human TIR8 polyclonal antibody previously validated in bovine tissues. Similarly to humans and mice, bovine TIR8 was found in the GI tract and kidney. Expression of TIR8 mRNA was also detected in lymph nodes, thymus and thyroid gland. Interestingly, several isoforms of bovine TIR8 were detected in the same organs, suggesting the occurrence of different post-translational processings.