Expression of serum amyloid A3 mRNA by inflammatory macrophages exposed to membrane glycoconjugates from Trypanosoma cruzi.

Differential display reverse transcriptase-polymerase chain reaction (PCR) was used to identify genes expressed by murine macrophages exposed to glycosylphosphatidylinositol-anchored mucin-like glycoproteins isolated from Trypanosoma cruzi trypomastigotes. Among the different PCR product bands identified in the differential display gel, one showed high homology with the serum amyloid A3 protein (SAA3). Northern blot assays showed augmentation of SAA3 mRNA expression by inflammatory macrophages exposed to live trypomastigotes or parasite glycolipids, as compared to unstimulated macrophages. Our results also showed the expression of SAA3 mRNA, in liver and heart from animals in the acute phase of Chagas disease. It is important that expression of SAA3 mRNA was closely associated with tissue parasitism and presence of inflammatory cells. Together, our findings indicate the possible involvement of SAA3 protein on immunopathology of Chagas disease and establish a new infectious disease model to study the pathophysiological role of this acute-phase protein.