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Correlations between peripheral differential leukocyte counts and carotid atherosclerosis in non-smokers
Z S Huang1, J S Jeng, C H Wang
1Department of Internal Medicine, College of Medicine, National Taiwan University Hospital, No 7. Chung-Shan South Road, Taipei 10016, Taiwan. barrat@tpts7.seed.net.tw
Insights
In male non-smokers, higher leukocyte, neutrophil, and monocyte counts correlate with carotid atherosclerosis presence and severity. Female non-smokers showed no such association, highlighting potential sex differences in atherosclerosis development.
Area of Science:
- Cardiovascular Research
- Immunology
- Atherosclerosis Pathophysiology
Background:
- Atherosclerosis is an immuno-inflammatory disease involving leukocytes.
- The link between peripheral monocyte count and atherosclerosis remains unclear, possibly due to confounding risk factors like smoking and hypercholesterolemia.
- Smoking elevates leukocyte counts, necessitating exclusion in studies investigating atherosclerosis and leukocyte counts.
Purpose of the Study:
- To investigate the association between peripheral leukocyte counts and carotid atherosclerosis in non-smokers.
- To explore potential sex differences in the relationship between leukocyte counts and atherosclerosis.
- To clarify the role of monocytes and neutrophils in atherogenesis.
Main Methods:
- Analysis of data from 1185 non-smoking individuals (571 males, 614 females) who underwent carotid duplex studies.
- Assessment of leukocyte, neutrophil, and monocyte counts.
- Correlation analysis between leukocyte counts and the presence/severity of carotid atherosclerosis, adjusted for age and body mass index.
Main Results:
- In male non-smokers, increased counts of all leukocytes, neutrophils, and monocytes were significantly associated with the presence of carotid atherosclerosis (P<0.005, P<0.001, P<0.05).
- A significant positive correlation was found between these leukocyte counts and the severity of carotid atherosclerosis in males, even after adjustments.
- No significant associations were observed between differential leukocyte counts and carotid atherosclerosis in female non-smokers.
Conclusions:
- Peripheral monocyte and neutrophil counts are linked to carotid atherosclerosis in male non-smokers.
- The absence of this association in females suggests sex-specific mechanisms in atherosclerosis development.
- Monocytes and neutrophils are likely key players in atherosclerosis, with potential sex-based differences in their involvement.
Abstract:
Substantial evidence clearly indicates the immuno-inflammatory nature of atherosclerosis and the important roles of monocytes and other leukocytes in atherogenesis. The relationship between atherosclerosis and the peripheral monocyte count, however, has been equivocal and uncertain so far. One possible reason may be an opposing effect of different major risk factors of atherosclerosis on the monocyte count, e.g. smoking increases the monocyte count while hypercholesterolemia is accompanied by a lower monocyte count. Since smoking is well shown to increase leukocyte counts prominently in weeks, our study included only non-smokers who participated in a health check program at our hospital from 1996 to 1998 and had received a carotid duplex study with extra payment. Our results revealed the followings: In male non-smokers (n=571), the presence of carotid atherosclerosis was associated with significant increases in the counts of all leukocyte, neutrophil, and monocyte (P<0.005,<0.001 and <0.05, respectively), and, after adjustments for age and body mass index, there were significant positive links between these three leukocyte counts and the severity of carotid atherosclerosis, judged by either the sum score of all carotid plaques or the score of the most severe carotid plaque. On the contrary, in female non-smokers (n=614), there was no significant link between differential leukocyte counts and either the presence or severity of carotid atherosclerosis. These results are compatible with recently recognized sex differences in the mechanism and pathophysiology of atherosclerosis, and together with relevant results in the literature, suggest that monocytes and neutrophils are the main types of leukocytes involved in atherosclerosis.