Histological changes and risk factor associations in type 2 atherosclerotic lesions (fatty streaks) in young adults.

OBJECTIVES: The purpose of this study was to investigate which histological changes associated with risk factors could contribute to the progression from the initial atherosclerotic lesions including fatty streaks to the advanced lesions. METHODS: We examined the associations of histomorphometric findings in the determined anatomical sites of mid-thoracic aortas (TAs) and left anterior descending coronary arteries (LADs) with major risk factors for atherosclerosis, using a young autopsied series from the the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. The histological classification by the American Heart Association was graded for 1013 TAs and 1009 LADs. Histometric study, including immunohistochemistry, was performed in type 2 lesions (fatty streaks) of TAs from 59 subjects and LADs from 45 ones. RESULTS: For the progression from the initial lesions into the advanced atherosclerotic lesions, the most effective lipid profiles were low plasma HDL-C in TA and elevated serum non-HDL-C in LAD. This lipid profile of each artery correlated with number or density of intimal smooth muscle cell-derived foam cells, respectively. The serum concentration of non-HDL-C correlated with macrophage foam cells in TAs. Hypertension and hyperglycemia were associated with increase of intimal area and/or collagen content in both arteries, but not with either types of foam cell proliferation. Smoking correlated with increased collagen content in TAs. CONCLUSION: There were histologically different ways of progressing from fatty streaks to advanced atherosclerotic lesions depending on the risk factors. For the atherosclerosis progression from type 2 lesions to advanced lesions, increase in number of smooth muscle cell-derived foam cells could be an important indicator.

Common variants in the periostin gene influence development of atherosclerosis in young persons.

OBJECTIVE: We investigated the influence of genetic variants (rare and common) in the gene encoding periostin (POSTN) on atherosclerosis as measured in arterial specimens from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. METHODS AND RESULTS: A comprehensive survey of common POSTN variants (87 single-nucleotide polymorphisms [SNPs]) in PDAY subjects (n = 2527) identified numerous SNPs associated with raised lesions in abdominal aorta and with fatty streaks in thoracic aorta. These SNPs belonged to a small number of correlation bins that spanned the entire locus. To examine effects of rare variants, we resequenced POSTN functional regions in PDAY cases with raised lesions (n = 291) and controls with no raised lesions (n = 294). However, we found no significant associations with case-control status for carriers of POSTN rare variants using the weighted-sum method for rare variant analysis. CONCLUSIONS: We identified common variants in POSTN that are associated with arterial lesions in young persons from the PDAY study. This finding strongly supports a role for periostin in atherogenesis, as suggested by recent proteomics analysis that found abundant expression of periostin in atherosclerotic lesions. Genetic variation may influence atherosclerosis via periostin's known involvement in multiple relevant pathways, including angiogenesis, vascular remodeling, and stimulation of migration and differentiation of vascular smooth muscle cells.

Heparin cofactor II in atherosclerotic lesions from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study.

Heparin cofactor II (HCII) is a serine protease inhibitor (serpin) that has been shown to be a predictor of decreased atherosclerosis in the elderly and protective against atherosclerosis in mice. HCII inhibits thrombin in vitro and HCII-thrombin complexes have been detected in human plasma. Moreover, the mechanism of protection against atherosclerosis in mice was determined to be the inhibition of thrombin. Despite this evidence, the presence of HCII in human atherosclerotic tissue has not been reported. In this study, using samples of coronary arteries obtained from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study, we explore the local relationship between HCII and (pro)thrombin in atherosclerosis. We found that HCII and (pro)thrombin are co-localized in the lipid-rich necrotic core of atheromas. A significant positive correlation between each protein and the severity of the atherosclerotic lesion was present. These results suggest that HCII is in a position to inhibit thrombin in atherosclerotic lesions where thrombin can exert a proatherogenic inflammatory response. However, these results should be tempered by the additional findings from this, and other studies, that indicate the presence of other plasma proteins (antithrombin, albumin, and alpha(1)-protease inhibitor) in the same localized region of the atheroma.

Thieno[2,3-c]isoquinolin-5-one, a potent poly(ADP-ribose) polymerase inhibitor, promotes atherosclerotic plaque regression in high-fat diet-fed apolipoprotein E-deficient mice: effects on inflammatory markers and lipid content.

We recently showed that poly(ADP-ribose) polymerase (PARP) is activated within atherosclerotic plaques in an animal model of atherosclerosis. Pharmacological inhibition of PARP or reduced expression in heterozygous animals interferes with atherogenesis and may promote factors of plaque stability, possibly reflecting changes in inflammatory and cellular factors consistent with plaque stability. The current study addresses the hypothesis that pharmacological inhibition of PARP promotes atherosclerotic plaque regression. Using a high-fat diet-induced atherosclerosis apolipoprotein E(-/-) mouse model, we demonstrate that administration of the potent PARP inhibitor, thieno[2,3-c]isoquinolin-5-one (TIQ-A), when combined with a regular diet regimen during treatment, induced regression of established plaques. Plaque regression was associated with a reduction in total cholesterol and low-density lipoproteins. Furthermore, plaques of TIQ-A-treated mice were highly enriched with collagen and smooth muscle cells, displayed thick fibrous caps, and exhibited a marked reduction in CD68-positive macrophage recruitment and associated foam cell presence. These changes correlated with a significant decrease in expression of monocyte chemoattractant protein-1 and intercellular cell adhesion molecule-1, potentially as a result of a robust reduction in tumor necrosis factor expression. The PARP inhibitor appeared to affect cholesterol metabolism by affecting acyl-coenzymeA/cholesterol acyltransferase-1 expression but exerted no effect on cholesterol influx or efflux as assessed by an examination of the ATP-binding cassette transporter-1 and the scavenger receptor-A expression levels in the different experimental groups. In accordance, PARP inhibition may prove beneficial not only in preventing atherogenesis but also in promoting regression of preexisting plaques.

Associations of arterial tissue lipids with coronary heart disease risk factors in young people.

OBJECTIVE: To examine the associations of the coronary heart disease (CHD) risk factors with lipid composition of arterial tissue in 397 autopsied subjects 15-34 years of age from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. METHODS AND RESULTS: We measured esterified cholesterol, free cholesterol, and phospholipid in the left circumflex coronary artery and two segments of the abdominal aorta, one of which is more susceptible to advanced atherosclerosis than the other, and also measured the major CHD risk factors. Non-HDL cholesterol concentration was positively associated, and HDL cholesterol concentration was negatively associated, with tissue lipids in the left circumflex coronary artery and the abdominal aorta. Hypertension was positively associated with tissue lipids in both arteries. Hyperglycemia was associated with tissue lipids in the left circumflex coronary artery and smoking with lipids in the abdominal aorta. PDAY risk scores summarize the effects of the CHD risk factors on advanced atherosclerosis. These risk scores, computed from the mutable risk factors, were associated with tissue lipids in the left circumflex coronary artery and both segments of the abdominal aorta. CONCLUSIONS: The CHD risk factors are associated with lipids in arterial tissue just as they are associated with gross and microscopic lesions. These results support the proposal that early control of risk factors is likely to prevent or delay progression of atherosclerosis and prevent or delay the onset of CHD.

Histological topographical comparisons of atherosclerosis progression in juveniles and young adults.

BACKGROUND: The histologically topographic comparisons on atherosclerosis progression among three anatomical sites, mid-thoracic and lower abdominal aorta and left anterior descending coronary artery (LAD) were performed using a young population (age 15-34 years) from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. METHODS AND RESULTS: The histological classification based on the American Heart Association grading scheme showed that in the thoracic aorta type 2 lesions (numerous macrophage foam cells with fine particles but no pools of extracellular lipid) appeared in the first 10-year age group, with no significant change in prevalence in the next 10 years. Lesions greater than type 2 were rarely seen in the thoracic aorta. Although type 2 lesions appeared later in the LAD than in the aorta, the lesions within the LAD progressed rapidly to more advanced lesions (types 4 and 5) or atheroma. Lesion development in the abdominal aorta was intermediate to lesion development in the thoracic aorta and the LAD. CONCLUSIONS: The most striking topographic difference on lesion progression among the three anatomical sites was the vulnerability of type 2 lesions to progress into advanced lesions. The histology study, including immunohistochemistry limited to the type 2 lesions suggested that lesion progression was related to the intimal thickness and the amount of collagen but not to the number of macrophage foam cells.

Comparison of coronary heart disease risk factors in autopsied young adults from the PDAY Study with living young adults from the CARDIA study.

BACKGROUND: Disease is sometimes best studied by examination of tissue obtained from autopsied individuals. Results derived from autopsied persons are considered biased because many factors influence the decision to perform an autopsy, and variables measured postmortem may be affected by changes immediately prior to death and emergency medical treatment. METHODS: The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study measured coronary heart disease risk factors postmortem in autopsied young adults 23-34 years of age dying from external causes (accidents, homicides, suicides). The Coronary Artery Risk Development in Young Adults (CARDIA) study measured risk factors in living subjects of similar ages. RESULTS: Within sex, race, and age groups, the differences in body mass index between PDAY and CARDIA were significant but small. The prevalences of hyperglycemia/diabetes within sex, race, and age groups were similar in PDAY and CARDIA; overall, blacks in PDAY, but not in CARDIA, had a higher prevalence than whites. Serum lipoprotein concentrations were slightly and significantly higher and significantly more variable in PDAY subjects than in CARDIA subjects; the greater variability was interpreted as due primarily to emergency medical treatment. Prevalences of smoking and hypertension were substantially higher in PDAY subjects. CONCLUSIONS: Although there were statistically significant differences, the overall similarity of the risk factors in the two studies supports the validity of investigating associations of risk factors measured postmortem with anatomically determined arterial lesions in autopsied young adults dying from external causes. The greater variability in postmortem serum measurements attenuates but does not obscure associations.

PDAY risk score predicts advanced coronary artery atherosclerosis in middle-aged persons as well as youth.

A risk score formula to estimate the probability of advanced atherosclerosis using coronary heart disease (CHD) risk factors was developed for persons 15-34 years of age by the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. We applied the PDAY risk score to autopsied individuals from the Community Pathology Study (CPS), a different population that included middle-aged as well as young subjects. The PDAY risk score was associated with extent of raised lesions in the coronary arteries of CPS cases 15-34 years of age. The PDAY risk score computed from only the modifiable risk factors was associated with extent of raised lesions in the coronary arteries of subjects 35-54 years of age. The association of the PDAY risk score with lesions in 15-34 year old CPS subjects validates the PDAY risk score. The associations in both younger (15-34 years) and older (35-54 years) subjects suggest a seamless progression of the effects of the modifiable risk factors on atherosclerosis from 15 to 54 years of age. These results support the proposal that early control of risk factors is likely to prevent or delay the onset of CHD.

Pathobiological determinants of atherosclerosis in youth risk scores are associated with early and advanced atherosclerosis.

OBJECTIVES: Atherosclerosis begins in childhood and progresses during adolescence and young adulthood. The Pathobiological Determinants of Atherosclerosis in Youth Study previously reported risk scores to estimate the probability of advanced atherosclerotic lesions in young individuals aged 15 to 34 years using the coronary heart disease risk factors (gender, age, serum lipoprotein concentrations, smoking, hypertension, obesity, and hyperglycemia). In this study we investigated the relation of these risk scores to the early atherosclerotic lesions. METHODS: We measured atherosclerotic lesions in the left anterior descending coronary artery, right coronary artery, and abdominal aorta and the coronary heart disease risk factors in persons 15 to 34 years of age who died as a result of external causes and were autopsied in forensic laboratories. RESULTS: Risk scores computed from the modifiable risk factors were associated with prevalence of microscopically demonstrable lesions of atherosclerosis (American Heart Association grade 1) in the left anterior descending coronary artery and with the extent of the earliest detectable gross lesion (fatty streaks) in the right coronary artery and abdominal aorta. Risk scores computed from the modifiable risk factors also were associated with prevalence of lesions of higher degrees of microscopic severity (intermediate as well as advanced) in the left anterior descending coronary artery and with extent of lesions of higher degrees of severity (intermediate and raised lesions) in the right coronary artery and abdominal aorta. CONCLUSIONS: Risk scores calculated from traditional coronary heart disease risk factors to identify individual young persons with high probability of having advanced atherosclerotic lesions also are associated with earlier atherosclerotic lesions, including the earliest anatomically demonstrable atherosclerotic lesion. These results support lifestyle modification in youth to prevent development of the initial lesions and the subsequent progression to advanced lesions and, thereafter, to prevent or delay coronary heart disease.

Aortic rhythmic wrinkling in youth: the PDAY study.

Transverse, white-streak 'wrinkles' in the aorta were first described as Querlinien (cross lines) or Wellenlinien (wave lines) in the German literature in the early 20th century. These rhythmic structures were previously thought to be artifacts of stretching and shrinkage of the aorta. Not until the 1970s was it proposed that the areas of rhythmic wrinkling (RW) might be part of the process of atherosclerosis. We analyzed 2,650 aortas from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study for prevalence, extent, and topographical distribution of these areas of RW. Furthermore, we investigated the possible relationship of RW to atherosclerotic sudanophilic stained 'fatty streaks' and elevated intimal lesions called 'raised lesions' (RL). This study provides evidence that (1) the prevalence of RW is fairly high in the aorta and occurs in a specific distribution in both the thoracic and abdominal aorta; (2) RW seems to precede the development of RL, with RL occurring in the same topographical areas as RW; and (3) RW may be associated with the subsequent development of advanced atherosclerosis, particularly raised lesions.

C-Peptide induces vascular smooth muscle cell proliferation: involvement of SRC-kinase, phosphatidylinositol 3-kinase, and extracellular signal-regulated kinase 1/2.

Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes mellitus. Recent data suggest a potential causal role of C-peptide in atherogenesis by promoting monocyte and T-lymphocyte recruitment into the vessel wall. The present study examined the effect of C-peptide on vascular smooth muscle cells (VSMCs) proliferation and evaluated intracellular signaling pathways involved. In early arteriosclerotic lesions of diabetic subjects, C-peptide colocalized with VSMCs in the media. In vitro, stimulation of human or rat VSMCs with C-peptide induced cell proliferation in a concentration-dependent manner with a maximal 2.6+/-0.8-fold induction at 10 nmol/L human C-peptide (P<0.05 compared with unstimulated cells; n=9) and a 1.8+/-0.2-fold induction at 0.5 nmol/L rat C-peptide (P<0.05 compared with unstimulated cells; n=7), respectively, as shown by [H3]-thymidin incorporation. The proliferative effect of C-peptide on VSMCs was inhibited by Src short interference RNA transfection, PP2, an inhibitor of Src-kinase, LY294002, an inhibitor of PI-3 kinase, and the ERK1/2 inhibitor PD98059. Moreover, C-peptide induced phosphorylation of Src, as well as activation of PI-3 kinase and ERK1/2, suggesting that these signaling molecules are involved in C-peptide-induced VSMC proliferation. Finally, C-peptide induced cyclin D1 expression as well as phosphorylation of Rb in VSMCs. Our results demonstrate that C-peptide induces VSMC proliferation through activation of Src- and PI-3 kinase as well as ERK1/2. These data suggest a novel mechanism how C-peptide may contribute to plaque development and restenosis formation in patients with insulin resistance and early type 2 diabetes mellitus.

Smoking is associated with advanced coronary atherosclerosis in youth.

Smoking is linked to atherosclerosis and coronary heart disease (CHD) in older adults. However, evidence that smoking affects coronary atherosclerosis in young people is incomplete. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Study collected arteries, blood, and other tissues from persons 15 to 34 years of age dying of external causes and autopsied in forensic laboratories. Lesions in the proximal left anterior descending coronary arteries (LAD) from 1127 subjects were graded microscopically according to the American Heart Association criteria. Among individuals with advanced lesions (Grade 4 or 5), smokers had a greater prevalence of Grade 5 lesions than non-smokers (odds ratio 9.61, 95% confidence interval 2.34-39.57), a difference suggesting that smoking accelerates the transition from Grade 4 to Grade 5 lesions. This association occurred among both men and women, and among persons with and without other CHD risk factors. The difference in qualities of advanced lesions suggests that smoking possibly accelerates the transition from Grade 4 to Grade 5 lesions by promoting thrombosis and accretion on the intimal surface of the plaque.

Comparison of coronary and aortic atherosclerosis in youth from Japan and the USA.

This paper reports the results of the largest autopsy-based comparative study of atherosclerotic lesions between young Japanese and Americans, aged 15-34 years and autopsied between 1987 and 1995, by analyzing the data from the Japanese second nation-wide study of atherosclerosis and Pathobiological Determinants of Atherosclerosis in Youth study in the USA. In the right coronary arteries, in Japanese, fatty streaks were well established in the second decade of life with very little increase in the remaining age groups up to age of 34 years. In contrast, in American subjects, the average percentage of surface involvement of fatty streaks and raised lesions proceeded steadily with age without an obvious plateau throughout the 20-year period. The extent and prevalence of the raised lesions was much greater in Americans than in Japanese in 25-29 and 30-34-year age groups. Moreover, the rate of progression of raised lesions was much more rapid in Americans. These findings are in keeping with the fact that coronary heart disease (CHD) death rates are much higher in the USA than in Japan. In light of data showing that the risk factor profiles for CHD have become very similar between the two countries, these differences need to be explained.

Risk scores predict atherosclerotic lesions in young people.

BACKGROUND: Atherosclerosis begins in childhood and progresses through young adulthood to form the lesions that cause coronary heart disease. These preclinical lesions are associated with coronary heart disease risk factors in young persons. METHODS: The Pathobiological Determinants of Atherosclerosis in Youth study collected arteries and samples of blood and other tissues from persons aged 15 to 34 years who died of external causes and underwent autopsy in forensic laboratories. We measured the coronary heart disease risk factors and atherosclerotic lesions in the coronary arteries (CAs) (n = 1117) and the abdominal aorta (n = 1458). RESULTS: We developed risk scores, normalized so that a 1-unit increase was equivalent to a 1-year increase in age, to estimate the probability of advanced atherosclerotic lesions in the CAs and the abdominal aorta from age, sex, serum lipoprotein concentrations, smoking, hypertension, obesity, and hyperglycemia. Odds ratios for a 1-unit increase in the risk scores were 1.18 (95% confidence interval, 1.14-1.22) for the CAs and 1.29 (95% confidence interval, 1.23-1.35) for the abdominal aorta. These risk scores had good discrimination (c-indexes: 0.78 for the CAs and 0.84 for the abdominal aorta) and were calibrated. The presence of abdominal aortic lesions increased the likelihood of having CA lesions. CONCLUSION: Risk scores calculated from traditional coronary heart disease risk factors provide a tool for identifying young individuals with a high probability of having advanced atherosclerotic lesions.

Elevated serum C-reactive protein levels and advanced atherosclerosis in youth.

OBJECTIVE: To determine the associations among serum C-reactive protein (CRP) concentration, age, sex, risk factors for coronary heart disease (CHD), and atherosclerosis in young people. METHODS AND RESULTS: In 1244 subjects 15 to 34 years of age, we measured gross atherosclerotic lesions in the right coronary artery (RCA) and abdominal aorta (AA) and American Heart Association (AHA) lesion grade in the left anterior descending (LAD) coronary artery; serum CRP, lipoprotein cholesterol, and thiocyanate (for smoking) concentrations; intimal thickness of renal arteries (for hypertension); glycohemoglobin (for hyperglycemia); and body mass index (for obesity). Serum CRP levels increased with age, were higher in women than in men, and were positively related to obesity and hyperglycemia. Serum CRP > or =10 mg/L was associated with more extensive gross raised lesions in the RCA after age 25 and in the AA after age 30. Serum CRP > or =3 was associated with a greater prevalence of AHA grade 5 lesions in the proximal LAD coronary artery after age 25. The associations of CRP with lesions were independent of the traditional CHD risk factors. CONCLUSIONS: Serum CRP level is independently associated with advanced atherosclerosis in young persons.

ACE insert/delete polymorphism and atherosclerosis.

We report on the results of a large autopsy study focusing upon the hypothesis that deletion of the Alu insert in the angiotensin converting enzyme (ACE) gene is associated with: (a) greater prevalence or extent of atherosclerosis in the aorta and coronary arteries; and (b) microscopic qualities of established atherosclerotic plaques in the coronary arteries. This study was conducted in young US black (n=290) and white (n=379) males using available materials and data from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study, a multi-center cooperative autopsy study organized in 1985 to explore the relationships of known cardiovascular risk factors to atherosclerosis in victims of accidents, homicides, or suicides in the age range of 15-34 years. The results provide strong evidence that ACE genotype may not be a predictor of either the prevalence or the extent of the lesions of atherosclerosis in the right coronary artery or the aorta of young adults, an observation that confirms previous studies that estimated the prevalence and extent of atherosclerosis using coronary angiography. In addition, the results suggest that ACE genotype does not contribute to the formation of atherosclerotic lesions that have the characteristics of vulnerable plaques in the left anterior descending coronary artery of young adults.

Histiocytic sarcoma with fatal duodenal ulcers.

Histiocytic sarcoma is an uncommon neoplasm of mature histiocytes with very poor outcome. We report an autopsy case of a true histiocytic sarcoma with characteristic symptoms of so-called "malignant histiocytosis of the intestine". The liver and spleen were enlarged, with remarkable tumor cell infiltration in the hepatic sinusoids and splenic sinuses. Tumor cells aggregated to form sporadic nodular lesions in the liver, which often showed coagulative necrosis. Infarcted lesions also occurred at the splenic subcapsular area. In addition, tumor cell infiltration was noted in the sinuses of bone marrow and lymph node. Tumor cells often demonstrated moderate pleomorphism with multinucleated giant cells. They were positive for CD68 and negative for T- and B-cell lineage markers, megakaryocytic markers, and CD30. Various examinations were done to rule out infection-associated hemophagocytic syndrome, and the absence of infectious diseases was revealed. Thus, the diagnosis of histiocytic sarcoma was made. Apart from these lesions, multiple ulcerations, some with fatal perforation, were found in the esophagus and duodenum. They showed only non-specific inflammatory changes without tumor cell involvement. The ulcers probably derived from ischemic condition through an embolic process caused by tumor cell infiltration elsewhere in the blood vessels at the periphery of the ulcers.

C-peptide induces chemotaxis of human CD4-positive cells: involvement of pertussis toxin-sensitive G-proteins and phosphoinositide 3-kinase.

Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes, a high-risk population for the development of a diffuse and extensive pattern of arteriosclerosis. The present study examined the effect of C-peptide on CD4(+) lymphocyte migration, an important process in early atherogenesis. C-peptide stimulated CD4(+) cell chemotaxis in a concentration-dependent manner. This process involves pertussis toxin-sensitive G-proteins as well as activation of phosphoinositide 3-kinase (PI 3-K). Biochemical analysis showed that C-peptide induced recruitment of PI 3-K to the cell membrane as well as PI 3-K activation in human CD4(+) cells. In addition, antidiabetic peroxisome proliferator-activated receptor gamma-activating thiazolidinediones inhibited C-peptide-induced CD4(+) cell chemotaxis as well as PI 3-Kgamma activation. Finally, immunofluorescence staining of thoracic artery specimen of diabetic patients showed intimal CD4(+) cells in areas with C-peptide deposition. Thus, C-peptide might deposit in the arterial intima in diabetic patients during early atherogenesis and subsequently attract CD4(+) cells to migrate into the vessel wall.

C-peptide colocalizes with macrophages in early arteriosclerotic lesions of diabetic subjects and induces monocyte chemotaxis in vitro.

OBJECTIVE: Increased levels of C-peptide, a cleavage product of proinsulin, circulate in patients with insulin resistance and early type 2 diabetes, a high-risk population for the development of a diffuse and extensive pattern of arteriosclerosis. This study tested the hypothesis that C-peptide might participate in atherogenesis in these patients. METHOD AND RESULTS: We demonstrate significantly higher intimal C-peptide deposition in thoracic aorta specimens from young diabetic subjects compared with matched nondiabetic controls as determined by immunohistochemical staining. C-peptide colocalized with monocytes/macrophages in the arterial intima of artery specimen from diabetic subjects. In vitro, C-peptide stimulated monocyte chemotaxis in a concentration-dependent manner with a maximal 2.3+/-0.4-fold increase at 1 nmol/L C-peptide. Pertussis toxin, wortmannin, and LY294002 inhibited C-peptide-induced monocyte chemotaxis, suggesting the involvement of pertussis toxin-sensitive G-proteins as well as a phosphoinositide 3-kinase (PI3K)-dependent mechanism. In addition, C-peptide treatment activated PI3K in human monocytes, as demonstrated by PI3K activity assays. CONCLUSIONS: C-peptide accumulated in the vessel wall in early atherogenesis in diabetic subjects and may promote monocyte migration into developing lesions. These data support the hypothesis that C-peptide may play an active role in atherogenesis in diabetic patients and suggest a new mechanism for accelerated arterial disease in diabetes.

Removal of cholesteryl esters from diet-induced atherosclerotic lesions in two long-term studies in rhesus monkeys.

In two long-term studies of dietary-cholesterol-induced atherosclerosis lesions in rhesus monkeys, we determined the fatty acid composition of cholesteryl esters in the arterial intima-media preparations. In the first study (2-year study) monkeys were fed an atherogenic diet for 2 years; in the second study, (5-year study), monkeys were fed the atherogenic diet for about 5.4 years. Dietary cholesterol was removed from regressed animals and the regression periods in the 2-year study were 30 and 52 weeks and in the 5-year study were 20, 30, 52, 101, and 191 weeks. In both studies in thoracic and abdominal aortic segments, the percent removal of 18:2 cholesteryl ester (CE) was small, whereas percent removal of 18:1 CE and other CEs was much higher. We postulate that 18:2 CE is not hydrolyzed to the extent comparable to 18:1 and other CEs in lesions. Perhaps 18:2 CE is not a preferred substrate for arterial neutral cholesterol ester hydrolase.