Increased expression of HDJ-2 (hsp40) in carotid artery atherosclerosis: Anovel heat shock protein associated with luminal stenosis and plaque ulceration

Purpose: Evidence suggests that both humoral and cellular autoimmune proces ses directed toward heat shock proteins (hsp) contribute to the pathogenesi s of atherosclerosis. We characterized a human hsp distinct from those prev iously characterized in atherosclerotic lesions, termed HDJ-2. Methods: To determine the role of HDJ-2 in atherosclerosis, we compared the level of HDJ-2 mRNA expression with the level of hsp60 and hsp70 mRNA expr ession in 26 carotid endarterectomy specimens and 17 normal arteries. The l evel of expression of HDJ-2 mRNA was also correlated to the presence of pla que ulceration and the degree of luminal stenosis associated with the lesio n. Results: The expression of HDJ-2 and hsp70 was significantly higher in caro tid artery plaques as compared with nor mal arteries: HDJ-2, 6.7 +/- 1.6 vs 0.1 +/- 0.04, (P = .001); hsp70, 9.5 +/- 0.9 vs 3.7 +/- 0.8, (P = .002). T here was no significant difference in hsp60 expression between carotid arte ry plaques and normal arteries (21.0 +/- 0.9 vs 20.6 +/- 0.8, P = .65). Inc reased HDJ-2 expression in carotid artery plaques was independent of hsp70 (Pearson correlation, r = 0.11; Bartlett chi (2) analysis, P = .71). Within the ulcerated plaque group, there was a correlation between degree of sten osis and high HDJ-2 mRNA expression (r = 0.896, P = .016). However, there w as no correlation between degree of stenosis and high HDJ-2 mRNA expression within the nonulcerated plaque group (r = 0.530, P = .076) or within the e ntire group of patients (r = 0.0085, P = .97). Conclusion: These results demonstrate that expression of HDJ-2 is significa ntly increased in atherosclerotic carotid artery plaques as compared with h sp60 and hsp70 and correlates with luminal stenosis in ulcerated atheroscle rotic carotid artery plaques.