Exploring PTX3 expression in Sus scrofa cardiac tissue using RNA sequencing

The prototypic long pentraxin PTX3 is a novel vascular inflammatory marker sharing similarities with the classic short pentraxin (C-reactive protein). PTX3 is rapidly produced and released by several cell types in response to local inflammation of the cardiovascular system. Plasma PTX3 levels are very low in normal conditions and increase in heart failure (HF) patients with advancing NYHA functional class, but its exact role during HF pathogenetic mechanisms is not yet established. No data about PTX3 cardiac expression in normal and pathological conditions are currently available, either in human or in large-size animals. Of the latter, the pig has a central role in "in vivo" clinical settings but its genome has not been completely sequenced and the PTX3 gene sequence is still lacking. The aim of this study was to sequence the PTX3 in Sus scrofa, whose sequence is not yet present in GenBank. Utilizing our knowledge of this sequence, PTX3 mRNA expression was evaluated in cardiac tissue of normal (n=6) and HF pigs (n=5), obtained from the four chambers. To sequence PTX3 gene in S. scrofa, the high homology between Homo sapiens and S. scrofa was exploited. Pig PTX3 mRNA was sequenced using polymerase chain reaction primers designed from human consensus sequences. The DNA, obtained from different RT-PCR reactions, was sequenced using the Sanger method. S. scrofa PTX3 mRNA, 1-336 bp, was submitted to GenBank (ID: GQ412351). The sequence obtained from pig cardiac tissue shared an 84% sequence identity with human homolog. The presence of PTX3 mRNA expression was detected in all the cardiac chambers sharing an increase after 3 weeks of pacing compared to controls (p=0.036 HF right atrium vs. N; p=0.022, HF left ventricle vs. N). Knowledge of the PTX3 sequence could be a useful starting point for future studies devoted to better understanding the specific role of this molecule in the pathogenesis of cardiovascular diseases.