Association of the IGF1/pregnancy-associated plasma protein-A system and adipocytokine levels with the presence and the morphology of carotid plaques in type 2 diabetes mellitus patients with stable glycaemic control

Pregnancy Associated Plasma Protein-A as a Cardiovascular Risk Marker in Patients with Stable Coronary Heart Disease During 10 Years Follow-Up-A CLARICOR Trial Sub-Study

Elevated pregnancy-associated plasma protein A (PAPP-A) is associated with mortality in acute coronary syndromes. Few studies have assessed PAPP-A in stable coronary artery disease (CAD) and results are conflicting. We assessed the 10-year prognostic relevance of PAPP-A levels in stable CAD. The CLARICOR trial was a randomized controlled clinical trial including outpatients with stable CAD, randomized to clarithromycin versus placebo. The placebo group constituted our discovery cohort (n = 1.996) and the clarithromycin group the replication cohort (n = 1.975). The composite primary outcome was first occurrence of cardiovascular event or death. In the discovery cohort, incidence rates (IR) for the composite outcome were higher in those with elevated PAPP-A (IR 12.72, 95% Confidence Interval (CI) 11.0-14.7 events/100 years) compared to lower PAPP-A (IR 8.78, 8.25-9.34), with comparable results in the replication cohort. Elevated PAPP-A was associated with increased risk of the composite outcome in both cohorts (discovery Hazard Ratio (HR) 1.45, 95% CI 1.24-1.70; replication HR 1.29, 95% CI 1.10-1.52). In models adjusted for established risk factors, these trends were attenuated. Elevated PAPP-A was associated with higher all-cause mortality in both cohorts. We conclude that elevated PAPP-A levels are associated with increased long-term mortality in stable CAD, but do not improve long-term prediction of death or cardiovascular events when added to established predictors.

Circulating adiponectin levels in relation to carotid atherosclerotic plaque presence, ischemic stroke risk, and mortality: A systematic review and meta-analyses

BACKGROUND

Low circulating levels of adiponectin, an anti-inflammatory and vasculoprotective adipokine, are associated with obesity, type 2 diabetes, and atherosclerotic disease. Presence of unstable plaques in the carotid artery is a known etiological factor causing ischemic strokes. Herein, we systematically reviewed the association between circulating adiponectin and progression of carotid atherosclerotic disease, particularly evaluating the occurrence of (1) carotid atherosclerotic plaques, (2) ischemic stroke, and (3) mortality in subjects who suffered a previous ischemic stroke.

METHODS

Medline, Embase, Biosis, Scopus, Web of Science, and Pubmed were searched for published studies and conference abstracts. The effect size and 95% confidence intervals (CIs) of the individual studies were pooled using fixed-effect or random-effect models. The quality of the eligible studies was evaluated using the Newcastle-Ottawa quality assessment scale. Sensitivity, subgroup, and meta-regression analyses were performed to address the impact of various risk factors on the association between adiponectin and ischemic stroke risk.

RESULTS

Twelve studies fulfilled the inclusion criteria for 3 independent meta-analyses. The association of increasing circulating adiponectin levels (5μg/mL-increment) with presence of carotid plaque was not conclusive (n=327; OR: 1.07; 95% CI: 0.85-1.35; 2 studies), whereas high adiponectin levels showed a significant 8% increase in risk of ischemic stroke (n=13,683; 7 studies), with a more sizable association observed among men compared to women. HDL was observed to have a marginal effect on the association between adiponectin and ischemic stroke, while other evaluated parameters were not found to be effect modifiers. A non-significant association of adiponectin with mortality was yielded (n=663; OR: 2.58; 95% CI: 0.69-9.62; 3 studies). Although no publication bias was evident, there was significant between-study heterogeneity in most analyses.

CONCLUSION

It appears that the direction of the relationship between adiponectin and carotid atherosclerotic plaque presence is dependent on the duration, severity, and nature of the underlying disease, while increased adiponectin levels were associated with an increase in risk for ischemic stroke. Lastly, the results from the mortality meta-analysis remain inconclusive. Future properly designed studies are necessary to further elucidate the role of adiponectin on atherosclerotic plaque development, and its related outcomes.

Female PAPP-A knockout mice are resistant to metabolic dysfunction induced by high-fat/high-sucrose feeding at middle age

Longevity and aging are influenced by common intracellular signals of the insulin/insulin-like growth factor (IGF)-1 pathway. Abnormally high levels of bioactive IGF-1 increase the development of various cancers and may contribute to metabolic diseases such as insulin resistance. Enhanced availability of IGF-1 is promoted by cleavage of IGF binding proteins (IGFBPs) by proteases, including the pregnancy-associated plasma protein-A (PAPPA). In vitro, PAPP-A is regulated by pro-inflammatory cytokines (PICs) such as interleukin (IL)-6 and tumor necrosis factor (TNF). Mice born with deficiency of the Papp-a gene (PAPP-A knockout (KO) mice) live ~30-40 % longer than their normal littermates and have decreased bioactive IGF-1 on standard diets. Our objective was to elucidate how the effects of high-fat, high-sucrose diet (HFHS) promote obesity, induce metabolic dysfunction, and alter systemic cytokine expression in PAPP-A KO and normal mice. PAPP-A KO mice fed HFHS diet for 10 weeks were more glucose tolerant and had enhanced insulin sensitivity compared to normal mice fed HFHS diet. PAPP-A KO mice fed HFHS diet had lower levels of pro-inflammatory cytokines (IL-2, IL-6, and TNF-α) compared to normal mice fed the same diet. However, anti-inflammatory cytokine levels (IL-4 and adiponectin) were higher in PAPP-A KO mice fed HFHS diet compared to normal mice fed HFHS. Circulating PAPP-A levels were elevated in normal mice fed an HFHS diet compared to normal mice fed a standard, low-fat, low-sucrose (LFLS) diet. Indirect calorimetry showed, at 10 weeks of feeding HFHS diet, significantly increased oxygen consumption (VO2) in PAPP-A KO mice fed HFHS diet compared to normal mice fed the same diet. Furthermore, respiratory quotient (RQ) was significantly lower in PAPP-A KO mice fed HFHS diet compared to normal (N) mice fed HFHS diet indicating PAPP-A KO mice fed HFHS diet are able to rely on fat as their primary source of energy more so than normal controls. We conclude that PAPP-A KO mice are resistant to the HFHS diet induction of metabolic dysfunction associated with higher levels of anti-inflammatory cytokines and a remarkably metabolic flexible phenotype and that some of the effects of HFHS diet in normal animals may be due to increased levels of PAPP-A.

Association of E-selectin gene polymorphism and serum PAPP-A with carotid atherosclerosis in end-stage renal disease

BACKGROUND

Atherosclerotic vascular disease represents a significant cause of morbidity and mortality in patients with end-stage renal disease (ESRD). The endothelium plays a crucial role in vascular inflammation. E-selectin is exclusively expressed on activated endothelial cells and is upregulated following an inflammatory response and oxidative stress, while serum pregnancy-associated plasma protein-A (PAPP-A) concentrations are related to the presence and stability of carotid atherosclerotic plaques.

OBJECTIVE

The aim of this study was to investigate whether there is an association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and the presence of carotid atherosclerosis in ESRD patients.

SUBJECTS AND METHODS

Seventy subjects were recruited into this study; 40 ESRD patients [age (mean ± SD) 43.42 ± 13.94 years] and 30 age- and gender-matched healthy individuals assigned to the control group. Polymerase chain reaction-restriction fragment length polymorphism was performed for the analysis of SELE rs5355C>T gene polymorphism, while serum PAPP-A concentrations were measured using electro-chemiluminescence immunoassay. Routine laboratory tests were measured on an automated chemistry analyzer. Carotid ultrasonographic studies were performed by a bilateral high-resolution B-mode ultrasound.

RESULTS

There was no significant relationship between the SELE rs5355C>T gene polymorphism and ESRD incidence. Serum PAPP-A levels were significantly higher in ESRD patients compared with controls [median (interquartile range) 5.8 (5.1-11.6) and 5.1 (4.1-6.7), respectively; p = 0.005]. Serum PAPP-A correlated positively with urea, creatinine, systolic and diastolic blood pressure (DBP). Serum PAPP-A showed a statistically significant increase in SELE rs5355TT versus CC in both patients and controls. There was no association on comparing right intima-media thickness (IMT), left IMT, right cross-sectional area (CSA) and left CSA with the CC, CT and TT genotypes of SELE rs5355C>T. No correlation between serum PAPP-A with each of the above-mentioned carotid doppler findings was observed. There was a statistically significant increase in DBP in TT genotype carriers when compared with CC genotype carriers (p = 0.009). Serum PAPP-A levels were higher in hypertensive ESRD patients when compared with normotensive ESRD patients. There was a statistically significant decrease in high-density lipoprotein cholesterol (HDL-C) in TT genotype carriers when compared with CT genotype carriers in the whole study group (p = 0.003). Serum PAPP-A correlated negatively with HDL-C.

CONCLUSION

The lack of a direct association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and IMT suggests that their hypothesized association with carotid atherosclerosis might reflect an indirect mechanism of SELE rs5355C>T gene polymorphism and serum PAPP-A with cardiovascular risk factors such as blood pressure and HDL-C rather than a direct effect on the vasculature.

Pregnancy-associated plasma protein A (PAPP-A) and preeclampsia

Pregnancy-associated plasma protein A (PAPP-A) is a key regulator of insulin-like growth factor bioavailability essential for normal fetal development. In maternal blood, this protein increases with gestational age and then rapidly decreases after delivery. It is routinely used for Down syndrome screening in the first trimester of pregnancy, and its decrease compared to a normal pregnancy indicates an increased risk for both chromosomal anomalies and adverse pregnancy outcomes. It belongs to a group of biomarkers that predict later preeclampsia development, primarily early onset preeclampsia; however, it should be combined with a Doppler ultrasonography of the uterine artery (pulsatile index) and other biochemical and maternal factors to achieve a higher detection rate with an acceptable false positivity rate. Some studies have demonstrated an even more pronounced decrease of PAPP-A in the early second trimester of pregnancy in women who subsequently develop preeclampsia compared with women who do not develop preeclampsia. Conversely, during the last trimester of pregnancy, its concentration increases even more in patients with preeclampsia than in patients without. It is also detectable at very low levels in nonpregnant individuals, and a higher concentration indicates an adverse effect in patients with acute coronary syndromes or stable atherosclerotic disease and in patients with end-stage renal disease who are being treated with hemodialysis.

PAPP-A in cardiac and non-cardiac conditions

Pregnancy-associated plasma protein-A (PAPP-A), a newly discovered member of insulin like growth factors (IGFs) axis, has been reported to be a biomarker in both cardiac and non-cardiac conditions. PAPP-A mainly acts as a protease cleaving IGF inhibitors - IGF binding proteins (IGFBPs), thereby setting free IGFs. In cardiac conditions, PAPP-A plays an important role in progressive atherosclerosis. As a biomarker, PAPP-A is not only sensitive, specific and early for diagnosis of acute coronary syndrome, but also an independent risk factor for all-cause mortality or combined cardiovascular events. In non-cardiac conditions, PAPP-A is a new anti-aging target. PAPP-A knock out (KO) mice have a prolonged lifespan than the wild type. In addition, PAPP-A is also a biomarker associated with malignant cancer and end stage renal disease.

The insulin-like growth factor-1 gene is associated with cerebral infarction in Japanese subjects

Atherosclerosis leads to cerebral infarction (CI) and the insulin/insulin-like growth factor-1 (IGF1) signaling pathway plays an important role in this process during adult life. The purpose of this study was to investigate the relationship between the human IGF1 gene and CI in the Japanese population via a case-control study that also included a separate analysis of the two gender groups. A total of 155 CI patients and 316 controls were genotyped for six single nucleotide polymorphisms (SNPs) of the human IGF1 gene (rs2162679, rs7956547, rs2288378, rs2072592, rs978458 and rs6218). All data were analyzed for three separate groups: the total subjects, men and women. The logistic regression analysis revealed that the GG + AG variant of rs2162679 (P = 0.047), the AA + GA variant of rs2072592 (P = 0.005) and the CC + TC variant of rs6218 (P = 0.015) exhibited a protective effect for CI in the total subject group. For the women and the total subjects groups, the overall distribution of the haplotype established by rs7956547-rs978458 was significantly different between the CI patients and the non-CI subjects. For the total subjects, the frequency of the T-G haplotype (rs7956547-rs978458) was also significantly higher (P = 0.034), whereas the frequency of the T-A haplotype (rs7956547-rs978458) was significantly lower (P = 0.008) in the CI patients versus the non-CI subjects. For women, the frequency of the T-A haplotype (rs7956547-rs978458) was significantly lower (P = 0.021) in the CI patients as compared with the non-CI subjects. The specific SNPs and haplotypes can be utilized as genetic markers for CI resistance or CI risk.

An update on markers of carotid atherosclerosis in patients with Type 2 diabetes

Carotid atherosclerosis constitutes an important cause of ischemic brain attack and stroke, accounting for up to 40% of cases of ischemic cerebrovascular disease. Type 2 diabetes mellitus is an independent risk factor for stroke and its recurrence. Thus, identifying diabetic patients who are at high risk of developing stroke is of great clinical importance. Noninvasive measurements of surrogate markers of atherosclerosis, such as novel serum biomarkers, can be helpful in detecting subclinical carotid disease, especially among individuals at the highest cardio-/cerebro-vascular risk. Previous studies have proposed an expanding body of serum biomarkers, such as C-reactive protein, fibrinogen, adipokines, cytokines and growth factors, as novel indicators of carotid atherosclerosis development that predict carotid-related clinical outcomes. Furthermore, those biomarkers are expected to assess the efficacy of both pharmaceutical and interventional strategies. Accordingly, it is increasingly clear that measuring biomarkers may improve the definition of cerebrovascular risk profile in patients with Type 2 diabetes mellitus.