Expression of molecular mediators of apoptosis and their role in the pathogenesis of lower-extremity varicose veins

Purpose: In an earlier study, we observed a significant decrease in apoptos is in varicose veins, as compared with healthy veins, indicating that dereg ulated apoptosis plays a role in the pathogenesis of varicosities. In addit ion, significant differences were noted in the expression and subcellular l ocalization of the cell cycle regulatory protein, cyclin D1 in varix tissue s, as compared with controls. Because cell cycle checkpoint controls are li nked to the signaling and execution of apoptotic cascades, we examined the expression of bcl-2 family members bar and bcl-x, known molecular mediators of apoptosis, and that of poly (ADP-ribose) polymerase (PARP), a downstrea m substrate of DNA cleavage. Methods: Twenty varicose vein specimens were retrieved from 20 patients (10 men, 10 women; mean age, 53.6 +/- 4.7 years) undergoing Lower-extremity va ricose vein excision. Healthy greater saphenous vein segments (n = 27) were obtained from 27 patients (14 men, 13 women; mean age, 59.5 +/- 2.4 years) undergoing infrainguinal arterial bypass grafting surgery. All tissues wer e distal portions. As per CEAP classification for chronic lower-extremity v enous disease, most of the patients were in class 2 for clinical signs (n = 11); some patients were in class 3 (n = 4) or class 4 (n = 4), and only on e patient was in class 5. Five 5-mum thick sections from formalin-fixed, pa raffin-embedded specimens were used as a means of immunohistochemically loc alizing the expression of bar, bcl-x, and PARP, and 10 random high-power fi elds per section were evaluated by two independent reviewers blinded to the clinical findings. Statistical analyses were conducted by means of chi (2) , analysis of variance, Student and Fisher exact t tests with StatView soft ware. Results: Immunoreactivity to pro-apoptotic bar was significantly higher in the normal veins (P < .001). Cytoplasmic expression of bd-x was prominent i n the cells of the vasa vasorum in both varicose and healthy veins. PARP ex pression was diminished in the varicose vein group, with 2.8 +/- 0.7 (P = . 01) and 1.4 +/- 0.5 (P = .05) cells per high-power field in the intima and media, respectively. Neither bar nor PARP was noted in the adventitia of va ricose veins, although their expression was detected in this layer of the c ontrol group (P < .001). Conclusion: The entry of smooth muscle cells into the apoptotic pathway may be regulated by the induction of bar in this model, because there is signi ficant presence of this pro-apoptotic protein in healthy veins. Both bar an d PARP are downregulated in varicose veins, as compared with healthy veins, and this may play a significant role in the pathogenesis of varicose veins .