Renata Nishiyama Ikegami, Joyce Tiyeko Kawakami, Dulcineia Saes Parra Abdalla, Raul Dias Santos, Roberto Kalil Filho, Jose Antônio Franchini Ramires and Maria de Lourdes Higuchi
Atherosclerosis is frequently associated with diabetes, obesity, metabolic syndrome and oxidized low density lipoproteins (oxLDL). Many studies have reported association of infection with such disorders, but with controversial results. In our view, these findings have relationship with technical differences. We showed previously, presence of infectious agents inside of ruptured plaque, using immunohistochemistry and electron microscopy. More recently, we detected Electron Lucent microparticles (ELMP) and Mycoplasma pneumoniae (Mp) lipoproteins in vulnerable plaques (VP).
However, we have interest to know if ELMPs contain Mp lipoprotein antigens and if they are related to oxLDL and plaque vulnerability.
Methods: We studied three groups of coronary arteries: VP (vulnerable plaque; n=13), stable plaques (SP; n=7), and normal arteries (NA; n=7). All cases were studied by immuno electron microscopy, and the mean numbers of ELMPs, oxLDL and Mp antigens, inside and outside ELMP, were obtained. Double colloidal immunogold particles (anti-oxLDL and anti-Mp) allowed the simultaneous localization of both antigens.
Results: There was a significant higher amount of ELMPs in VP, with positive dots for both oxLDL and Mp antigens inside them, compared to other two groups (p<0.01). Mp and oxLDL antigens were co-localized in lipidic nanoparticles intra ELMPs, showing positive correlation (r=0.60; P=0.04). High amount of oxLDL and Mp antigens extra ELMPs were seen in VP, but not in stable plaques.
Conclusion: Plaque vulnerability in atherosclerosis may be related to presence of ELMPs, containing M. pneumoniae lipoproteins and oxLDL. We hypothesized that M. pneumoniae lipoproteins oxidation could be a mechanism for this association. However, further data are necessary to prove this hypothesis.