Association of serum amyloid A with subclinical atherosclerosis in women with gestational diabetes

Serum amyloid A and metabolic disease: evidence for a critical role in chronic inflammatory conditions

Serum amyloid A (SAA) subtypes 1-3 are well-described acute phase reactants that are elevated in acute inflammatory conditions such as infection, tissue injury, and trauma, while SAA4 is constitutively expressed. SAA subtypes also have been implicated as playing roles in chronic metabolic diseases including obesity, diabetes, and cardiovascular disease, and possibly in autoimmune diseases such as systemic lupus erythematosis, rheumatoid arthritis, and inflammatory bowel disease. Distinctions between the expression kinetics of SAA in acute inflammatory responses and chronic disease states suggest the potential for differentiating SAA functions. Although circulating SAA levels can rise up to 1,000-fold during an acute inflammatory event, elevations are more modest (∼5-fold) in chronic metabolic conditions. The majority of acute-phase SAA derives from the liver, while in chronic inflammatory conditions SAA also derives from adipose tissue, the intestine, and elsewhere. In this review, roles for SAA subtypes in chronic metabolic disease states are contrasted to current knowledge about acute phase SAA. Investigations show distinct differences between SAA expression and function in human and animal models of metabolic disease, as well as sexual dimorphism of SAA subtype responses.

Serum amyloid A1 and pregnancy zone protein in pregnancy complications and correlation with markers of placental dysfunction

BACKGROUND

Hypertensive disorders of pregnancy (preeclampsia, gestational hypertension, and chronic hypertension), diabetes mellitus, and placental dysfunction confer an increased risk of long-term maternal cardiovascular disease. Preeclampsia is also associated with acute atherosis that involves lesions of uteroplacental spiral arteries, resembling early stages of atherosclerosis. Serum amyloid A1 is involved in hypercoagulability and atherosclerosis and may aggregate into amyloid-aggregations of misfolded proteins. Pregnancy zone protein may inhibit amyloid aggregation. Amyloid is involved in Alzheimer's disease and cardiovascular disease; it has been identified in preeclampsia, but its role in preeclampsia pathophysiology is unclear.

OBJECTIVE

We hypothesized that serum amyloid A1 would be increased and pregnancy zone protein decreased in hypertensive disorders of pregnancy and diabetic pregnancies and that serum amyloid A1 and pregnancy zone protein would correlate with placental dysfunction markers (fetal growth restriction and dysregulated angiogenic biomarkers) and acute atherosis.

STUDY DESIGN

Serum amyloid A1 is measurable in both the serum and plasma. In our study, plasma from 549 pregnancies (normotensive, euglycemic controls: 258; early-onset preeclampsia: 71; late-onset preeclampsia: 98; gestational hypertension: 30; chronic hypertension: 9; diabetes mellitus: 83) was assayed for serum amyloid A1 and pregnancy zone protein. The serum levels of angiogenic biomarkers soluble fms-like tyrosine kinase-1 and placental growth factor were available for 547 pregnancies, and the results of acute atherosis evaluation were available for 313 pregnancies. The clinical characteristics and circulating biomarkers were compared between the pregnancy groups using the Mann-Whitney U, chi-squared, or Fisher exact test as appropriate. Spearman's rho was calculated for assessing correlations.

RESULTS

In early-onset preeclampsia, serum amyloid A1 was increased compared with controls (17.1 vs 5.1 µg/mL, P<.001), whereas pregnancy zone protein was decreased (590 vs 892 µg/mL, P=.002). Pregnancy zone protein was also decreased in diabetes compared with controls (683 vs 892 µg/mL, P=.01). Serum amyloid A1 was associated with placental dysfunction (fetal growth restriction, elevated soluble fms-like tyrosine kinase-1 to placental growth factor ratio). Pregnancy zone protein correlated negatively with soluble fms-like tyrosine kinase-1 to placental growth factor ratio in all study groups. Acute atherosis was not associated with serum amyloid A1 or pregnancy zone protein.

CONCLUSION

Proteins involved in atherosclerosis, hypercoagulability, and protein misfolding are dysregulated in early-onset preeclampsia and placental dysfunction, which links them and potentially contributes to future maternal cardiovascular disease.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

The prognostic value of serum amyloid A for long-term mortality among patients with subclinical carotid atherosclerosis

BACKGROUND AND PURPOSE

Despite extensive research in the last decade, the role of serum amyloid A (SAA) in atherogenesis remains highly controversial. The aim of this study was therefore to assess whether SAA is associated with long-term mortality in patients with subclinical carotid artery disease.

METHODS

One thousand sixty-five patients with neurological asymptomatic carotid atherosclerosis as evaluated by duplex sonography were prospectively followed for cause-specific mortality.

RESULTS

During a median of 11.8 years, a total of 549 deaths, including 362 cardiovascular deaths, were recorded. Patients who died within the follow-up period had significantly higher baseline SAA serum levels compared to those who survived (12.9 vs 9.5 mg/dL; P < 0.001). In univariable Cox regression analysis, the risk of all-cause and cardiovascular mortality significantly increased in patients with elevated serum levels of SAA (crude hazard ratio for cardiovascular mortality per increase of 1 SD of SAA levels was 1.14, 95% CI 1.08-1.22], P < 0.0001). However, SAA lost its significance after adjusting for high-sensitivity C-reactive protein (hsCRP), suggesting that SAA might not be directly associated with atherogenesis, but rather be a mere reflection of the individual patient's inflammatory status.

CONCLUSIONS

Serum amyloid A is not independently associated with (cardiovascular) mortality in patients with subclinical carotid atherosclerosis.

Lipopolysaccharide-binding protein (LBP) reverses the amyloid state of fibrin seen in plasma of type 2 diabetics with cardiovascular co-morbidities

Type 2 diabetes (T2D) has many cardiovascular complications, including a thrombotic propensity. Many such chronic, inflammatory diseases are accompanied (and may be exacerbated, and possibly even largely caused) by amyloid fibril formation. Recognising that there are few strong genetic associations underpinning T2D, but that amyloidogenesis of amylin is closely involved, we have been seeking to understand what might trigger the disease. Serum levels of bacterial lipopolysaccharide are raised in T2D, and we recently showed that fibrin(ogen) polymerisation during blood clotting can be affected strongly by LPS. The selectivity was indicated by the regularisation of clotting by lipopolysaccharide-binding protein (LBP). Since coagulopathies are a hallmark of T2D, we wondered whether they might too be caused by LPS (and reversed by LBP). We show here, using SEM and confocal microscopy, that platelet-poor-plasma from subjects with T2D had a much greater propensity for hypercoagulability and for amyloidogenesis, and that these could both be reversed by LBP. These data imply that coagulopathies are an important feature of T2D, and may be driven by ‘hidden’ LPS. Given the prevalence of amyloid formation in the sequelae of diabetes, this opens up novel strategies for both the prevention and treatment of T2D.

Atherosclerosis associated with dynamic inflammation changes after multifactorial intervention in short-duration type 2 diabetes: A randomized, controlled, 10-year follow-up trial

PURPOSE

To analyze the impact of dynamic changes in inflammation on atherosclerosis in short-duration type 2 diabetes after multifactorial intervention.

METHODS

In this randomized controlled study, a total of 150 type 2 diabetes patients who had a mean age of 49.8±7.3years, 51% male, with disease duration <1year and without evidence of atherosclerosis were randomized into an intensive intervention group (IG), in which patients received multiple risk factors intervention by the special project team and tried to reach the pre-determined intervention goals, and a conventional group (CG), in which patients received standard diabetes care by the clinic doctor. All patients recieved intervention study for 7 years, then underwent a 3-year observational follow-up study. The primary endpoints were occurrence of subclinical atherosclerosis, defined as the intima-media thickness of the common carotid artery (CC-IMT)≥1.0mm or formation of atherosclerosis plaques, and the occurrence of cardiovascular events.

RESULTS

68 patients in IG and 65 patients in CG completed the 10-year study. The cumulative incidence of subclinical atherosclerosis was 30.7% vs 57.3% (IG vs CG, HR 0.36, 95% CI 0.22-0.60, P<0.0001) and that of cardiovascular events was 12.0% vs 22.7% (IG vs CG, HR 0.46, 95% CI 0.21-0.98, P=0.0516). High sensitivity C-reactive protein (hs-CRP) reduction from baseline to the 10-year follow-up was -1.54mg/L (IG) and -0.67mg/L (CG) with difference (IG minus CG) of -0.87mg/L(95% CI -0.72 to -1.02, P=0.008) and the natural logarithm of serum amyloid A (SAA) reduction was -4.04 (IG) and -1.44 (CG) with difference (IG minus CG) of -2.60 (95% CI -2.30 to -2.90, P=0.002). The decrease in general score of inflammatory markers (combination of hs-CRP and SAA) was independently associated with subclinical atherosclerosis (OR=0.65, P=0.045) and cardiovascular events (OR=0.60, P=0.042).

CONCLUSIONS

Dynamic changes in inflammation act as an important factor that affects the occurrence of atherosclerosis in type 2 diabetes patients. Multifactorial intensive intervention can reduce systemic low-grade inflammation and delay the occurrence of atherosclerosis in short-duration type 2 diabetes.

Association of gestational diabetes mellitus (GDM) with subclinical atherosclerosis: a systemic review and meta-analysis

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with an elevated risk of adverse health outcomes such as type 2 diabetes and cardiovascular diseases. Carotid intima-media thickness (cIMT) is increasingly used as a noninvasive marker for subclinical atherosclerosis. Whether there is a direct correlation between GDM and elevated cIMT is still controversial.

METHODS

PubMed, Embase and reference lists of relevant papers were reviewed. Studies assessing the relationship between GDM and cIMT were included. Weighted Mean Difference (WMD) of cIMT was calculated using random-effect models.

RESULTS

Fifteen studies with a total of 2247 subjects were included in our analysis, giving a pooled WMD of 0.05 (95% confidence interval [CI] 0.03 -0.07). Furthermore, meta regression and subgroup analysis found that the association between GDM and larger cIMT already existed during pregnancy, and this relation was stronger in obese GDM patients.

CONCLUSIONS

GDM in and after pregnancy is associated with subclinical atherosclerosis. Weight control may be helpful to prevent cardiovascular diseases for GDM patients.

Gestational diabetes mellitus and cardiovascular risk after pregnancy

Gestational diabetes mellitus (GDM) affects many women in pregnancy and is enhanced by epidemic conditions of obesity, increasing age at the time of the first pregnancy, stressful life conditions, a sedentary lifestyle with less physical activity and unhealthy nutrition with highly processed, high-calorie food intake. GDM does not affect the mother and offspring in pregnancy alone, as there is compelling evidence of the long-term effects of the hyperglycemic state in pregnancy postpartum. Type 2 diabetes mellitus, cardiovascular disease and metabolic syndrome are more common in GDM women, and even the offspring of GDM women are reported to have higher obesity rates and a higher risk for noncommunicable diseases. Early prevention of risk factors seems to be key to overcoming the vicious cycle of cardiometabolic disease onset.

Increased endothelial inflammation, sTie-2 and arginase activity in umbilical cords obtained from gestational diabetic mothers

Objective

The aim of this study was to determine subclinical inflammation in umbilical vein derived endothelial cells (HUVECs) obtained from Asian Indian subjects with gestational diabetes (GDM) and to determine levels of angiogenic factors and arginase activity in their cord blood.

Methods

This case-control study included 38 control and 30 GDM subjects. Subjects were confirmed as GDM based on 75g oral glucose tolerance test (OGTT) conducted in the second trimester of pregnancy. Angiogenic markers and arginase activity were measured in cord blood by ELISA and colorimetric methods respectively. Endothelial inflammation was assessed through adhesion of PKH26-labelled leukocytes onto HUVEC monolayer obtained from the study groups. Gene and surface expression of adhesion molecules were confirmed via reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry respectively.

Results

The study revealed increased adhesion of leukocytes to HUVECs isolated from GDM subjects compared to controls. HUVECs of babies born to GDM mothers had increased surface and mRNA expression of E-selectin. sTie2 levels were significantly higher in the cord blood for GDM subjects (3869 ± 370 ng/L) compared to controls (3045 ± 296 ng/L). Furthermore, arginase activity was higher in cord blood of GDM mothers as opposed to the control group (7.75 ± 2.4 µmoles of urea/ml/hour vs 2.88 ±0.49 µmoles of urea/ml/hour; p-value= 0.019). Spearman’s correlation analysis revealed positive correlation of cord blood arginase activity with glucose intolerance (ρ=0.596, p=0.004) and post load glucose values (ρ=0.472, p=0.031) of mothers observed during the second trimester of pregnancy.

Conclusions

HUVECs derived from Asian Indian GDM mothers, exhibit signs of sub-clinical endothelial inflammation along with increased levels of sTie2 and arginase activity in their cord blood serum.