Inflammasome Activation Aggravates Cutaneous Xanthomatosis and Atherosclerosis in ACAT1 (Acyl-CoA Cholesterol Acyltransferase 1) Deficiency in Bone Marrow.

Objective- ACAT1 (Acyl-CoA cholesterol acyltransferase 1) esterifies cellular free cholesterol, thereby converting macrophages to cholesteryl ester-laden foam cells in atherosclerotic lesions and cutaneous xanthoma. Paradoxically, however, loss of ACAT1 in bone marrow causes the aggravation of atherosclerosis and the development of severe cutaneous xanthoma in hyperlipidemic mice. Recently, it has been reported that cholesterol crystals activate NLRP3 (NACHT, LRR [leucine-rich repeats], and PYD [pyrin domain] domain-containing protein 3) inflammasomes, thereby contributing to the development of atherosclerosis. The present study aimed to clarify the role of NLRP3 inflammasomes in the worsening of atherosclerosis and cutaneous xanthoma induced by ACAT1 deficiency. Approach and Results- Ldlr-null mice were transplanted with bone marrow from WT (wild type) mice and mice lacking ACAT1, NLRP3, or both. After the 4 types of mice were fed high-cholesterol diets, we compared their atherosclerosis and skin lesions. The mice transplanted with Acat1-null bone marrow developed severe cutaneous xanthoma, which was filled with numerous macrophages and cholesterol clefts and had markedly increased expression of inflammatory cytokines, and increased atherosclerosis. Loss of NLRP3 completely reversed the cutaneous xanthoma, whereas it improved the atherosclerosis only partially. Acat1-null peritoneal macrophages showed enhanced expression of CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein) and TNF-α (tumor necrosis factor-α) but no evidence of inflammasome activation, after treatment with acetylated LDL (low-density lipoprotein). Conclusions- Elimination of ACAT1 in bone marrow-derived cells aggravates cutaneous xanthoma and atherosclerosis. The development of cutaneous xanthoma is induced mainly via the NLRP3 inflammasome activation.

[Familial hypercholesterolemia - past and present. My experiences and findings in our group of patients with familial hypercholesterolemia]. / Familiární hypercholesterolemie vcera a dnes. Vlastní zkusenosti a nálezy u naseho souboru nemocných s familiární hypercholesterolemií

Currently, the familial hypercholesterolemia (FH) rises the interest. The reason is that this genetic disorder is targeted by newly emerged and highly effective hypolipidemic agents, PCSK-9 inhibitors, lomitapid and mipomersen. Present paper discusses 2 patient study groups, before 50 years and nowadays. Although direct statistical analysis is impossible some changes in clinical features of FH might be found over the course of the time. In fact, the basic FH characteristic has not changed dramatically. Severe isolated hypercholesterolemia with total cholesterol 9-10 mmol/l, LDL-cholesterol 7-8 mmol/l and normal values of triglycerides dominates in laboratory analysis. Interestingly, the values of triglycerides increase and almost reach the pathological range in comparison to the values from the period 50 years ago. The values of HDL-cholesterol are normal. Manifestation of CHD in male patients over 40 years of age and in female patients over 50 years of age is not exceptional (rarely occur cases of myocardial infarction in third decade of age). Typical clinical manifestation of FH is xanthomatosis. The early detection and aggressive treatment in FH patients cause that xanthoma tendinosum, xanthelesma and arcus lipoides are less frequent as decades ago. Obesity, diabetes mellitus (DM) and hypertension do not belong to typical clinical sign of FH.

Late effects of childhood cancer treatment: severe hypertriglyceridaemia, central obesity, non alcoholic fatty liver disease and diabetes as complications of childhood total body irradiation.

BACKGROUND: Childhood cancer survivors may develop a number of endocrine complications linked to organ failure, such as hypogonadism, diabetes and growth hormone deficiency. However, increasing evidence now suggests that total body irradiation treatment, specifically, is linked with future risk of insulin resistance, hepatic steatosis and dyslipidaemia, possibly because total body irradiation affects adipocyte differentiation and impairs subcutaneous adipose tissue depot expansion during times of positive energy balance. CASE REPORT: We describe a 20-year-old woman who developed pancreatitis with severe hypertriglyceridaemia (serum triglycerides > 300 mmol/l) that required plasmapheresis. She had received total body irradiation prior to her bone marrow transplant at age 6 years for relapsed acute lymphoblastic leukaemia. She developed ovarian failure at age 12 years. At age 15 years she was noted to have hyperglycaemia, increased blood pressure, hepatic steatosis and mild hypertriglyceridaemia. She presented with severe hypertriglyceridaemia and eruptive xanthoma, and developed pancreatitis 12 h after admission. She was treated with plasmapheresis and intravenous insulin and made an excellent recovery. We implicate and discuss total body irradiation as the major contributing factor to her severe hypertriglyceridaemia, compounded by worsening glycaemic control, oestrogen deficiency and a changing adult lifestyle. CONCLUSION: Children who have received total body irradiation are at risk of diabetes and an exaggerated form of the metabolic syndrome with hypertriglyceridaemia, which can be life-threatening. We suggest that survivors of total body irradiation treatment require careful lifelong monitoring of their metabolic status.

Pharmacologic suppression of hepatic ATP-binding cassette transporter 1 activity in mice reduces high-density lipoprotein cholesterol levels but promotes reverse cholesterol transport.

BACKGROUND: The role of hepatic ATP-binding cassette transporter 1 (ABCA1) in maintaining plasma high density lipoprotein cholesterol (HDL-C) levels is well established, but its role in reverse cholesterol transport (RCT) is unclear. Probucol is a compound that reduces HDL-C levels but also reduces atherosclerosis in animal models and xanthomas in humans. The aim of the present study was to test the hypothesis that probucol inhibits hepatic ABCA1 activity, thereby reducing HDL-C levels but promoting RCT from macrophages. METHODS AND RESULTS: Wild-type (WT) C57BL/6 mice and scavenger receptor class B type I (SR-BI) knockout mice were fed a chow diet containing 0.5% probucol or normal chow for 2 weeks. In WT mice, probucol, despite decreasing HDL-C by >80%, effectively maintained macrophage RCT. In SR-BI knockout mice, probucol also substantially reduced HDL-C but significantly increased macrophage RCT. Furthermore, probucol significantly enhanced the excretion of HDL-derived cholesterol into feces in both WT and SR-BI knockout mice. Probucol inhibited ABCA1-dependent cholesterol efflux from mouse primary hepatocytes, and this effect was shown to be responsible for the effect of probucol on increasing the fecal excretion of HDL-derived cholesterol in vivo. CONCLUSIONS: We demonstrate that pharmacological inhibition of hepatic ABCA1 activity with probucol reduced HDL-C levels but promoted RCT through diversion of HDL-derived cholesterol from efflux back into plasma instead to excretion in the bile. These results explain the beneficial effects of probucol on atherosclerosis and xanthomas despite its HDL-lowering effects and suggest that inactivation of hepatic ABCA1 leads to increased RCT despite reducing plasma HDL-C levels.

Practice of lipoprotein apheresis and short-term efficacy in children with homozygous familial hypercholesterolemia: Data from an international registry.

BACKGROUND AND AIMS: Homozygous familial hypercholesterolemia (hoFH) may cause life-threatening atherosclerotic cardiovascular disease in childhood. Lipoprotein apheresis (LA) is considered a pivotal treatment option, but data on its efficacy, safety and optimal performance are limited. We therefore established an international registry on the execution and outcomes of LA in HoFH children. Here we report LA policies and short-term outcomes. METHODS: We approached centers worldwide, involved in LA in children with hoFH for participation. We collected information on clinical and treatment characteristics on patients aged 0-19 years between November 2016 and November 2018. RESULTS: We included 50 children, treated at 15 sites. Median (IQR) LDL-C levels at diagnosis, on medication and on LA were 19.2 (16.2-22.1), 14.4 (10.8-16.7) mmol/L and 4.6 mmol/L, respectively. Median (IQR) time between diagnosis and start of LA was 2.8 (1.0-4.7) years. Six (12%) patients developed cardiovascular disease during that period. Most children received LA either weekly (43%) or biweekly (37%). Seven (17%) patients reached mean LDL-C levels <3.5 mmol/L, all of them treated at least weekly. Xanthomas were present in 42 (84%) patients at diagnosis and disappeared completely in 19 (45%) on LA. Side effects of LA were minor. There were significant differences in LA conduction between sites in terms of frequency, responsible medical specialities and vascular access. CONCLUSIONS: LA is a safe treatment and may effectively lower LDL-C in children with HoFH. However, there is room for improvement with respect to time of onset and optimization of LA therapy in terms of frequency and execution.

Lapaquistat acetate, a squalene synthase inhibitor, changes macrophage/lipid-rich coronary plaques of hypercholesterolaemic rabbits into fibrous lesions.

BACKGROUND AND PURPOSE: Inhibition of squalene synthesis could transform unstable, macrophage/lipid-rich coronary plaques into stable, fibromuscular plaques. We have here treated WHHLMI rabbits, a model for coronary atherosclerosis and myocardial infarction, with a novel squalene synthase inhibitor, lapaquistat acetate (TAK-475). EXPERIMENTAL APPROACH: Young male WHHLMI rabbits were fed a diet supplemented with lapaquistat acetate (100 or 200 mg per kg body weight per day) for 32 weeks. Serum lipid levels were monitored every 4 weeks. After the treatment, lipoprotein lipid and coenzyme Q10 levels were assayed, and coronary atherosclerosis and xanthomas were examined histopathologically or immunohistochemically. From histopathological and immunohistochemical sections, the composition of the plaque was analysed quantitatively with computer-assisted image analysis. Xanthoma was evaluated grossly. KEY RESULTS: Lapaquistat acetate decreased plasma cholesterol and triglyceride levels, by lowering lipoproteins containing apoB100. Development of atherosclerosis and xanthomatosis was suppressed. Accumulation of oxidized lipoproteins, macrophages and extracellular lipid was decreased in coronary plaques of treated animals. Treatment with lapaquistat acetate increased collagen concentration and transformed coronary plaques into fibromuscular plaques. Lapaquistat acetate also suppressed the expression of matrix metalloproteinase-1 and plasminogen activator inhibitor-1 in the plaque and increased peripheral coenzyme Q10 levels. Increased coenzyme Q10 levels and decreased very low-density lipoprotein cholesterol levels were correlated with improvement of coronary plaque composition. CONCLUSION AND IMPLICATIONS: Inhibition of squalene synthase by lapaquistat acetate delayed progression of coronary atherosclerosis and changed coronary atheromatous plaques from unstable, macrophage/lipid accumulation-rich, lesions to stable fibromuscular lesions.

[Eruptive xanthomas with hypertriglyceridemia]. / Eruptive Xanthome bei Hypertriglyzeridämie.

Eruptive xanthomas are often associated with elevated plasma levels of triglyceride-rich lipoproteins and may be a marker for occult hyperlipidemia, diabetes mellitus or pancreatitis. A 42-year-old woman presented with the acute onset of disseminated eruptive xanthomas secondary to hyperlipidemia associated with diabetes and concomitant acute pancreatitis. She improved after optimized insulin therapy and intensified treatment of hyperlipidemia. Eruptive xanthomas should be diagnosed early and lead to further metabolic evaluations.

Preventive effect of pravastatin sodium, a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on coronary atherosclerosis and xanthoma in WHHL rabbits.

In this paper, we examined whether the development of atherosclerosis in the Watanabe heritable hyperlipidemic (WHHL) rabbit, an animal model of familial hypercholesterolemia in man, could be prevented by the reduction of serum cholesterol levels. Pravastatin sodium (the generic name of CS-514), a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, was used as a cholesterol-lowering drug. The drug was administered orally to 12 WHHL rabbits (2-3 months old) at a dose of 50 mg/kg per day for 24 weeks, and 13 animals were given water as control. In the treated group, serum cholesterol, phospholipid and triacylglycerol levels were significantly reduced by 28%, 32% and 16%, respectively, as compared with those of the control group. Although the prevention of development of the aortic atherosclerosis was not significant, the progression of coronary atherosclerosis was significantly prevented. The incidence of atherosclerosis in four main coronary arteries was reduced from 42% (control group) to 19% (treated group, P less than 0.01), and the development of lesion of coronary arteries evaluated by area of lesion was reduced from 19.7% (control group) to 9.1% (treated group, P less than 0.05). Histopathological findings supported the above observations. In addition, development of xanthoma in digital joints was also reduced from 90.4% (control group) to 58.3% (treated group, P less than 0.005). These results suggest that the development of coronary atherosclerosis and xanthoma in WHHL rabbit was reduced by continuous reduction of serum cholesterol levels treated with pravastatin sodium.

Combination treatment with troglitazone, an insulin action enhancer, and pravastatin, an inhibitor of HMG-CoA reductase, shows a synergistic effect on atherosclerosis of WHHL rabbits.

We examined whether improving insulin resistance augments the antiatherosclerotic effect of LDL reduction. Since WHHL rabbits show hyperinsulinemia and insulin resistance, we administered troglitazone (100 mg/kg), an insulin action enhancer, pravastatin sodium (50 mg/kg), an HMG CoA reductase inhibitor, and a combination of both drugs to 2-month-old WHHL rabbits for 32 weeks. As compared to the control, total cholesterol levels in the plasma and LDL were decreased significantly by 20% in the pravastatin and combination groups. Basal immunoreactive insulin levels and insulin index were decreased significantly by approximately 50% in the troglitazone and combination groups. Surface lesion area of atherosclerosis on the thoracic aorta was decreased significantly by 36% in the combination group and was less in the troglitazone group. Coronary atherosclerosis was decreased significantly by 39% in the combination group and was less in the pravastatin and troglitazone groups. The collagen content in the plaques was decreased in the troglitezone and combination groups and the extracellular lipid deposits were decreased in the pravastatin and combination groups. The incidence and severity of xanthomata in the digital joints were also decreased significantly in the three treated groups. In conclusion, the antiatherogenic effect of the combination treatment is stronger than that of the monotherapy.

Recurrent verruciform xanthoma of the vulva.

Verruciform xanthoma is a rare, benign, mucocutaneous, nondestructive lesion characterized by proliferation of non-Langerhans lipid-rich histiocytes. We describe the clinical and pathologic findings in a 30-year-old female with recurrent verruciform xanthoma of the vulva 8 years after initial therapy. The differential diagnosis includes seborrheic keratosis, verruca simplex, condyloma acuminatum, granular cell myoblastoma, vulvar intraepithelial neoplasia, bowenoid papulosis, erythroplasia of Queyrat, and verrucous carcinoma.

L-arginine prevents xanthoma development and inhibits atherosclerosis in LDL receptor knockout mice.

BACKGROUND: The potential antiatherosclerotic actions of NO were investigated in four groups of mice (n = 10 per group) lacking functional LDL receptor genes, an animal model of familial hypercholesterolemia. Group 1 was fed a regular chow diet. Groups 2 through 4 were fed a 1.25% high-cholesterol diet. In addition, group 3 received supplemental L-arginine and group 4 received L-arginine and N omega-nitro-L-arginine (L-NA), an inhibitor of NO synthase (NOS). METHODS AND RESULTS: Animals were killed at 6 months; aortas were stained with oil red O for planimetry and with antibodies against constitutive and inducible NOSs. Plasma cholesterol was markedly increased in the animals receiving the high-cholesterol diet. Xanthomas appeared in all mice fed the high-cholesterol diet alone but not in those receiving L-arginine. Aortic atherosclerosis was present in all mice on the high-cholesterol diet. The mean atherosclerotic lesion area was reduced significantly (P < .01) in the cholesterol-fed mice given L-arginine compared with those receiving the high-cholesterol diet alone. The mean atherosclerotic lesion area was significantly larger (P < .01) in cholesterol-fed mice receiving L-arginine + L-NA than in those on the high-cholesterol diet alone. Within the atherosclerotic plaques, endothelial cells immunoreacted for endothelial cell NOS; macrophages, foam cells, and smooth muscle cells immunostained strongly for inducible NOS and nitrotyrosine residues. CONCLUSIONS: The data indicate that L-arginine prevents xanthoma formation and reduces atherosclerosis in LDL receptor knockout mice fed a high-cholesterol diet. The abrogation of the beneficial effects of L-arginine by L-NA suggests that the antiatherosclerotic actions of L-arginine are mediated by NOS. The data suggest that L-arginine may be beneficial in familial hypercholesterolemia.

Partial ileal bypass surgery in the treatment of heterozygous familial hypercholesterolemia: a review.

Partial ileal bypass (PIB) surgery is a method in the treatment of heterozygous familial hypercholesterolemia (FH). Since the first report in 1964 about 150 cases of FH who underwent the surgical procedure have been described. This number is very low when compared to other types of cholesterol-lowering treatment. On average, PIB decreases the level of plasma total cholesterol by 35% in FH patients, and the surgical procedure can be considered the most effective, single cholesterol-lowering method. PIB-induced reduction of plasma cholesterol is permanent. Further decrease of plasma cholesterol may be obtained in combination with an inhibitor of cholesterol biosynthesis. PIB specifically lowers plasma LDL cholesterol; the concentration of HDL cholesterol is not systematically influenced. The mechanism underlying the hypocholesterolemic action of PIB is discussed. Until now there is no evidence that PIB reduces atherosclerotic coronary death in FH patients. After PIB more patients experience improvement of angina pectoris rather than deterioration (15 versus 2 out of 41), but the number of patients is too small to allow solid conclusions. In 50% of FH patients PIB may cause regression of xanthomata. Out of 209 hyperlipidemic patients described, 14 patients had postoperative complications, which caused death in 3 patients. Diarrhea is the most common side-effect of PIB; out of 99 operated patients serious diarrhea troubled 38 patients, whereas 40 patients had minor complaints during the first year postoperatively. Diarrhea may persist as long as 10 years after PIB. There is no evidence that PIB enhances gallstone formation and severely impairs liver function, but PIB may increase the incidence of renal stones. It is suggested that PIB can be considered in the treatment of FH. However, in each individual case the disadvantages and possible advantages should be carefully weighed out, and this consideration should form the basis to decide whether or not surgery is indicated.

Treatment of type III hyperlipoproteinemia with gemfibrozil to retard progression of coronary artery disease.

Eight type III hyperlipoproteinemic (type III HLP), homozygous E 2/2 patients were enrolled in two periods of long-term diet-gemfibrozil treatment. The combined therapy resulted in highly significant decreases in their low-density lipoprotein cholesterol, very-low density lipoprotein cholesterol, very-low density lipoprotein triglycerides, and increases in their high-density lipoprotein cholesterol during the first treatment period of 24 to 28 months. Type III HLP reasserted itself following an 8-week interruption of gemfibrozil therapy. Resumption of gemfibrozil therapy again lowered the high lipid-lipoprotein concentrations of these patients toward normal. Tuboeruptive xanthomata, palmar xanthoma, and xanthoma striata palmare subsided with treatment. Follow-up coronary arteriograms performed 2.5 to 3.0 years after initiation of diet-drug treatment showed stabilization of coronary arterial lesions, which was associated with improvement in exercise tolerance.