Researchers identify indicator of atherosclerotic progression
MedWire News: Increases in the number of smooth muscle cell (SMC)-derived foam cells could be an important indicator of atherosclerotic progression, study findings suggest.
The progression from American Heart Association (AHA)-defined type 2 lesions (fatty streaks) to AHA type 3 lesions (pre-atheromas) is the process that transforms reversible, initial lesions into those that progress to irreversible, clinically significant lesions, explain Satoki Homma (Keio University, Shinjuku-ku, Tokyo) and colleagues.
However, "the association among histomorphometric findings… and risk factors associated with the progression of atherosclerotic lesions has not been systematically explored."
The team therefore studied which histologic features of type 2 lesions of the thoracic aorta (TA) and the left anterior descending coronary artery (LAD) were associated with risk factors related to the progression of type 2 lesions to more advanced lesion types. In total, 59 sections of the TA and 45 of the LAD were included in the analysis.
In the TA, low levels of high-density lipoprotein (HDL) cholesterol showed the strongest association with lesion progression (from initial atherosclerotic lesions [≤AHA type 2] to advanced lesions [≥AHA type 3]), while in the LAD, age and male gender showed the strongest associations. Among risk factors including age and gender, elevated serum nonHDL cholesterol levels showed the most significant associations in the LAD.
In type 2 lesions, an increase in intimal SMC foam cells was associated with low levels of HDL cholesterol in the TA and with increases in nonHDL cholesterol in the LAD. In contrast, the number of macrophage foam cells correlated positively with nonHDL cholesterol in the TA and negatively with HDL cholesterol in the LAD.
Hypertension and hyperglycemia were associated with increases in intimal area and/or collagen content in both arteries, but not with either type of foam cell proliferation. Smoking correlated with increased collagen content in the TA.
Thus, "although the most effective lipid profiles for the progression from initial lesions to advanced ones were different in the TA and LAD, they are both highly associated with the proliferation of SMC foam cells in type 2 lesions of each artery," explain the authors.
Of note, "low HDL cholesterol is particularly an important risk factor for primary prevention, because it exhibits a powerful effect on the progression of early atherosclerotic lesions, even in the arterial sections such as TA, which typically are resistant to atherosclerosis progression," conclude Homma et al in the journal Atherosclerosis.
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By Nikki Withers