Augustinus H. M. Smelt

Mortality over two centuries in large pedigree with familial hypercholesterolaemia: family tree mortality study

Abstract Objective: To estimate all cause mortality from untreated familial hypercholesterolaemia free from selection for coronary artery disease. Design: Family tree mortality study. Setting: Large pedigree in Netherlands traced back to a single pair of ancestors in the 19th century. Subjects: All members of pedigree aged over 20 years with 0.5 probability of carrying a mutation for familial hypercholesterolaemia. Main outcome measure: All cause mortality. Results: A total of 70 deaths took place among 250 people analysed for 6950 person years. Mortality was not increased in carriers of the mutation during the 19th and early 20th century; it rose after 1915, reached its maximum between 1935 and 1964 (standardised mortality ratio 1.78, 95% confidence interval 1.13 to 2.76; P=0.003), and fell thereafter. Mortality differed significantly between two branches of the pedigree (relative risk 3.26, 95% confidence interval 1.74 to 6.11; P=0.001). Conclusions: Risk of death varies significantly among patients with familial hypercholesterolaemia. This large variability over time and between branches of the pedigree points to a strong interaction with environmental factors. Future research is required to identify patients with familial hypercholesterolaemia who are at extreme risk and need early and vigorous preventive measures. What is already known on this topic Familial hypercholesterolaemia is associated with excess mortality in families of patients who present with cardiovascular disease Population data are lacking What this study adds Many untreated patients with familial hypercholesterolaemia (about 40%) reach a normal life span Standardised mortality ratio was normal in the 19th century and rose to a peak in the 1930s to 1960s The variation in mortality suggests an interaction between genetic and environmental factors

Severe hypertriglyceridemia with insulin resistance is associated with systemic inflammation: reversal with bezafibrate therapy in a randomized controlled trial

PURPOSE To determine whether hypertriglyceridemia is associated with systemic inflammation, which may contribute to the increased cardiovascular risk in patients who have hypertriglyceridemia. In addition, we investigated whether fibrates reverse this inflammatory state. PATIENTS AND METHODS Serum lipid levels, body mass index, insulin resistance, and inflammatory parameters were compared between 18 patients who had severe hypertriglyceridemia without cardiovascular disease and 20 normolipidemic controls. We measured the ex vivo production capacity of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 after whole-blood stimulation with lipopolysaccharide, as well as circulating levels of C-reactive protein and fibrinogen. A randomized controlled trial was conducted to determine whether bezafibrate (400 mg administered daily for 6 weeks) affected these parameters in hypertriglyceridemic patients. RESULTS When compared with normolipidemic controls, hypertriglyceridemic patients had significantly lower high-density lipoprotein (HDL) cholesterol and higher triglyceride levels, body mass index, and insulin resistance. In addition, hypertriglyceridemic patients had a significantly higher production capacity of TNF-alpha (mean difference, 11 700 pg/mL; 95% confidence interval [CI]: 7800 to 15,700 pg/mL]) and IL-6 (mean difference, 20,400 pg/mL; 95% CI: 7800 to 32,900 pg/mL), and higher levels of C-reactive protein (mean difference, 0.8 mg/L; 95% CI: 0.1 to 2.4 mg/L) and fibrinogen (mean difference, 0.8 g/dL; 95% CI: 0.3 to 1.3 g/dL). Bezafibrate therapy significantly increased HDL cholesterol levels, reduced triglyceride and insulin resistance levels, and reduced production capacity of TNF-alpha and IL-6, as well as levels of C-reactive protein and fibrinogen. CONCLUSION Systemic inflammation is present in patients who have the clinical phenotype that is associated with severe hypertriglyceridemia, and may contribute to the increased risk of cardiovascular disease in these patients. Bezafibrate has anti-inflammatory effects in these patients.

Not Acute but Chronic Hypertriglyceridemia Is Associated With Impaired Endothelium-Dependent Vasodilation: Reversal After Lipid-Lowering Therapy by Atorvastatin

There is controversy regarding the relation between hypertriglyceridemia (HTG) and endothelial function. This study was designed to investigate endothelial function in a patient group with chronic HTG, before and during lipid-lowering therapy by atorvastatin. In addition, the effects of acute HTG on endothelial function were studied in normolipidemic individuals. Eight male patients with chronic HTG were studied before and after 6 weeks of lipid-lowering treatment with 80 mg atorvastatin once daily. Ten age-matched control subjects were studied at baseline and immediately after a high-dose infusion of artificial triglycerides. The endothelium-dependent response to serotonin was attenuated in the HTG group, whereas the response to acetylcholine was comparable to the response in the control group. The response to the endothelium-independent vasodilator nitroprusside was comparable in both groups. In response to atorvastatin therapy, serum triglyceride and cholesterol levels decreased significantly by 43% (paired t test, P=0.017) and 38% (paired t test, P=0.012), respectively. After 6 weeks of treatment, the forearm blood flow response to serotonin improved from 63% to 106% (ANOVA, P<0.001). Induction of acute HTG in the control subjects did not affect the forearm blood flow responses to serotonin and nitroprusside; however, the response to acetylcholine was paradoxically increased. In conclusion, patients with chronic HTG have an impaired endothelium-dependent vasodilation to serotonin that is normalized after 6 weeks of lipid-lowering therapy by atorvastatin.

The prevalence of subclinical hypothyroidism at different total plasma cholesterol levels in middle aged men and women: a need for case‐finding?

In order to determine whether screening of thyroid function is justified in patients with hypercholesterolaemia, we determined the prevalence of subclinical hypothyroidism at different levels of total plasma cholesterol in middle‐aged men and women.

Additional risk factors influence excess mortality in heterozygous familial hypercholesterolaemia

Life expectancy of patients with familial hypercholesterolaemia is decreased. Some untreated patients reach a normal life span and, therefore, additional risk factors and the type of mutation in the low-density lipoprotein (LDL) receptor gene are likely to influence the clinical outcome. We determined all cause mortality in kindreds with the disorder, who were untreated, in order to study (a) additional risk factors for coronary artery disease (CAD) and (b) the types of LDL receptor gene mutations that may contribute to a poor prognosis. The mortality in all 855 first-degree relatives of 113 unrelated patients was compared to the Dutch population after standardisation for age, gender, and calendar period. Analyses restricted to affected relatives could have underestimated the mortality risk due to lack of information about severe cases, who died prematurely. Therefore, all first-degree relatives were analysed and as a result the standardised mortality ratios (SMRs) exhibit only 50% of the excess mortality from familial hypercholesterolaemia. We observed 190 deaths in 32048 person-years leading to an overall SMR of 1.34 (95% confidence interval (CI) 1. 16-1.55, P=0.001). High excess mortality occurred in males between age 40 and 54 (SMR 2.34, 95% CI 1.60-3.31, P<0.001). The excess mortality decreased during the last decades. This change of mortality over calendar time shows that additional risk factors modulate the mortality from the disorder. The SMR of 62 families referred with premature CAD was 1.62 (95% CI 1.32-1.93, P<0.001) and the SMR was 1.10 (95% CI 0.86-1.34, P=0.4) in 51 families without premature CAD. The mortality risk of kindreds with null alleles was similar to that of kindreds with other mutations. In conclusion, the burden of the untreated disorder occurred mainly among middle-aged males and was not influenced by the type of mutation. Additional risk factors increased excess mortality significantly and are highlighted by the presence of premature CAD among first-degree relatives. This underscores the need for active identification of all hypercholesterolaemic relatives of such patients.

Effects of Fish Oil on Oxidation Resistance of VLDL in Hypertriglyceridemic Patients

In hypertriglyceridemic (HTG) patients the addition of fish oil to the diet causes a marked reduction in the concentration of triglyceride-rich lipoproteins in the serum. To investigate the effects of fish oil on the oxidation resistance of VLDL and LDL in HTG patients, nine male patients received 1 g/d fish oil (containing 55.7% n-3 polyunsaturated fatty acids [PUFAS] and l U alpha-tocopherol/g fish oil) for 6 weeks followed by 5 g/d fish oil for an additional 6 weeks. Cu(2+)-induced oxidation of VLDL and LDL was measured by continuous monitoring of conjugated dienes. Supplementation with 1 g/d fish oil caused hardly any changes in the n-3 PUFA content of lipoproteins or lipoprotein concentrations in serum. However, supplementation with 5 g/d fish oil resulted in a significant increase of n-3 PUFA content in VLDL (from 2.5% to 6.4% of total fatty acids) and LDL (from 3.2% to 6.4% of total fatty acids), decreases in serum triglyceride, VLDL triglyceride, and VLDL cholesterol concentrations of 54%, 56%, and 40%, respectively, and an increase in LDL cholesterol of 23%. The lag times of VLDL and LDL oxidation decreased from 197 to 140 minutes (-29%) and 101 to 86 minutes (-15%), respectively. At the end of the 5 g/d fish oil supplementation the lag times of VLDL and LDL oxidation were correlated with their respective n-3 PUFA content (r = -.67; P < .05 and r = -.79; P < .02, respectively). Before and at the end of supplementation with 5 g/d fish oil the lag times and propagation rates of VLDL oxidation also correlated with the total number of double bonds in all PUFAs of VLDL. We conclude that fish oil supplementation strongly reduces serum concentrations of total triglycerides, VLDL triglycerides, and VLDL cholesterol. However, in HTG patients fish oil supplementation increased the serum LDL cholesterol concentration and the susceptibility of VLDL and LDL to oxidation.

Triglycerides and gallstone formation

Changes in bile acid (BA) metabolism and gallbladder function are critical factors in the pathogenesis of gallstones. Patients with hypertriglyceridemia (HTG) - often overweight and insulin resistant - are at risk for gallstone disease. The question arises whether HTG itself contributes to gallstone formation or whether gallstone disease only associates with this disorder. Triglycerides are formed in response to fluxes of non-esterified fatty acids and glucose. Hypertriglyceridemia results from either overproduction of triglycerides by the liver, impaired lipolysis or a combination of both. Hyperinsulinemia, as observed in the insulin resistant state, stimulates very low-density lipoprotein (VLDL)-triglyceride synthesis. Peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptor (FXR) and hepatocyte nuclear factor 4α (HNF4α) are the nuclear receptors involved in the regulation of lipogenesis. Microsomal triglyceride transfer protein (MTP) is involved in the production of VLDL and its activation is also under control of transcription factors as FXR and Forkhead box-O1 (FoxO1). Triglyceride and BA metabolism are linked. There is an inverse relationship between bile acid fluxes and pool size and VLDL production and SHP (small heterodimer partner) and FXR are the link between BAs and TG metabolism. BAs are also ligands for FXR and G-protein-coupled receptors, such as TGR5. FXR activation by BAs suppresses the expression of MTP, transcription factor sterol regulatory element binding protein (SREBP)-1c and other lipogenic genes. LXRs stimulate lipogenesis whereas FXRs inhibit the metabolic process. Synthesis of BAs from cholesterol occurs either via the classical pathway (7α-hydroxylation of cholesterol; CYP7A1) or via the alternate pathway (CYP39A1 or CYP7B1). BAs induce FXR, which inhibits CYP7A1 transcription by activation of SHP and inhibition of HNF4α transactivation. Bile composition (supersaturation with cholesterol), gallbladder dysmotility, inflammation, hypersecretion of mucin gel in the gallbladder and slow large intestinal motility and increased intestinal cholesterol absorption may contribute to the pathogenesis of cholesterol gallstones. In HTG patients supersaturated bile may be related to the presence of obesity rather than to HTG itself. Contraction and relaxation of the gallbladder are regulated by neuronal, hormonal and paracrine factors. Postprandial gallbladder emptying is regulated by cholecystokinin (CCK). Poor postprandial gallbladder contraction may be due to the magnitude of the CCK response and to the amount of CCK receptors in the gallbladder smooth muscle cells. In the fasting state gallbladder motility is associated with the intestinal migrating motor complex (MMC) activity and with elevated plasma motilin levels. Fibroblast growth factor (FGF19), produced on arrival of bile acids in the ileum, is also important for gallbladder motility. Gallbladder motility is impaired in HTG patients compared to BMI matched controls. There is evidence that the gallbladder in HTG is less sensitive to CCK and that this sensitivity improves after reversal of high serum TG levels by use of TG lowering agents. In hypertriglyceridemia TG lowering therapy (fibrates or fish-oil) is essential to prevent cardiovascular disease and pancreatitis. Fibrates, however, also increase the risk for cholelithiasis by increasing biliary cholesterol saturation and by reduction of bile acid synthesis. On the other hand fish-oil decreases biliary cholesterol saturation. Fish-oil may increase bile acid synthesis by activation of 7alpha-hydroxylase and may inhibit VLDL production and secretion through activation of nuclear factors and increased apoB degradation. In HTG patients, gallbladder motility improves during bezafibrate as well as during fish-oil therapy. The question remains whether improvement of gallbladder motility and increased lithogenicity of bile by bezafibrate therapy counteract each other or still result in gallstone formation in HTG patients.

Hyperlipoproteinemia affects cytokine production in whole blood samples ex vivo. The influence of lipid-lowering therapy

Low-density lipoprotein (LDL)-receptor deficient mice, thus hypercholesterolemic, combine protection against infection with an ex vivo two- to threefold higher pro-inflammatory cytokine production in macrophages. A pro-inflammatory cytokine profile ex-vivo is also associated with survival of gram-negative sepsis in man. We hypothesized that high lipoprotein levels would be associated with a pro-inflammatory cytokine production and could explain the resistance to fatal infection. We treated 10 patients with familial hypercholesterolemia (FH) with HMG-CoA reductase inhibitors, and 13 patients with endogenous hypertriglyceridemia (HTG) with fibrates. Blood samples were stimulated ex vivo with lipopolysaccharide (LPS), to assess the cytokine production capacity. FH patients had significantly lower tumor necrosis factor-alpha (TNF-alpha) production, compared to normolipidemic controls (P=0. 001). Lipid lowering treatment in FH patients did not affect TNF-alpha production. HTG patients showed significantly higher TNF-alpha production at baseline than matched normolipidemic controls (P<0.001), while lowering of serum triglycerides in these patients resulted in a significant decrease in TNF-alpha production (P=0.019). The IL-10 production was not affected. These data refute our hypothesis that high LDL-cholesterol levels are associated with a pro-inflammatory cytokine production capacity. In contrast, the study suggests that very-low-density lipoprotein (VLDL) in hypertriglyceridemic patients augments TNF-alpha production.

Decreased PLTP mass but elevated PLTP activity linked to insulin resistance in HTG: effects of bezafibrate therapy

Hypertriglyceridemia (HTG) is associated with insulin resistance, increased cholesteryl ester transfer (CET), and low HDL cholesterol. Phospholipid transfer protein (PLTP) may be involved in these relationships. Associations between CET, lipids, insulin resistance, CETP and PLTP activities, and PLTP mass were investigated in 18 HTG patients and 20 controls. Effects of 6 weeks of bezafibrate treatment were studied in HTG patients. HTG patients had higher serum triglycerides, insulin resistance, free fatty acid (FFA), and CET, lower levels of HDL cholesterol (−44%) and PLTP mass (−54%), and higher CETP (+20%) and PLTP activity (+48%) than controls. Bezafibrate reduced triglycerides, CET (−37%), insulin resistance (−53%), FFA (−48%), CETP activity (−12%), PLTP activity (−8%), and increased HDL cholesterol (+27%), whereas PLTP mass remained unchanged. Regression analysis showed a positive contribution of PLTP mass (P = 0.001) but not of PLTP activity to HDL cholesterol, whereas insulin resistance positively contributed to PLTP activity (P < 0.01). Bezafibrate-induced change in CET and HDL cholesterol correlated with changes in CETP activity and FFAs, but not with change in PLTP activity. Bezafibrate-induced change in PLTP activity correlated with change in FFAs (r = 0.455, P = 0.058). We propose that elevated PLTP activity in HTG is related to insulin resistance and not to increased PLTP mass. Bezafibrate-induced diminished insulin resistance is associated with a reduction of CET and PLTP activity.

Bezafibrate reduces heart rate and blood pressure in patients with hypertriglyceridemia.

ObjectiveIn hypertriglyceridemic patients, hypertension occurs frequently and may be associated with hyperinsulinemia and elevated plasma levels of free fatty acids (FFA). Besides the lipid-lowering effects, fibrates have been shown to reduce blood pressure in hypertensive patients. The present stud