Retrospective Study of IDegLira, a New Fixed-Ratio Combination, in Japanese Patients With Type 2 Diabetes Mellitus: Analysis of Background Factors Affecting Effectiveness After 6 Months of Treatment.

Background: The aim of the study was to provide real-world data on the effectiveness and safety of a new fixed-ratio combination, insulin degludec/liraglutide (IDegLira) injection in Japanese patients with type 2 diabetes mellitus (T2DM). Methods: The primary endpoint was the change in glycated hemoglobin (HbA1c) level 6 months after the introduction of IDegLira. We also examined the rate of achievement of target HbA1c 7% and the individualized HbA1c targets set for each patient. Baseline characteristics associated with the change in HbA1c were also assessed. Seventy-five patients with T2DM were included in the analysis. Results: After the initiation of IDegLira, HbA1c decreased significantly from baseline with a change of -1.81% (baseline 9.61% and at 6 months 7.80%; P < 0.001). At baseline, the achievement rate of 7% HbA1c was 2.67% (n = 2), which increased to 36.0% (n = 27) after 6 months of IDegLira introduction (P < 0.05). The attainment rate of individualized HbA1c targets, which were set considering each patient's characteristics, improved from 2.67% (n = 2) to 49.3% (n = 37) (P < 0.001). Regardless of sex, body mass index, estimated glomerular filtration rate, duration of diabetes, or history of glucagon-like peptide-1 receptor agonist use, IDegLira significantly reduced HbA1c, but a higher C-peptide index was associated with a greater reduction in HbA1c. Conclusion: In this study, initiation of IDegLira in a real-world clinical setting was beneficial in lowering HbA1c in Japanese T2DM patients with inadequate glycemic control with existing therapy.

A Novel Missense MEN1 Mutation in a Sporadic Case of Multiple Endocrine Neoplasia Type 1 Complicated with Papillary Thyroid Carcinoma.

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic disorder, resulting from MEN1 gene abnormalities, which causes tumors mainly in the endocrine glands. We experienced a sporadic case of MEN1 complicated with papillary thyroid carcinoma (PTC) and found a novel missense mutation in the patient's MEN1 gene. Her older sister, who showed no typical symptom of MEN1, had a history of PTC, suggesting the presence of another genetic factor involved in PTC development. This case suggests the importance of an individual's genetic background in the development of MEN1 complications.

Retrospective Analysis of the Effectiveness of Oral Semaglutide in Type 2 Diabetes Mellitus and Its Effect on Cardiometabolic Parameters in Japanese Clinical Settings.

Glucagon-like peptide-1 receptor agonists (GLP-1RA) have a more potent glycated hemoglobin (HbA1c)-lowering effect than existing therapies and are widely used for treating type 2 diabetes mellitus (T2DM). Once-daily oral semaglutide is the world's first oral GLP-1RA. This study aimed to provide real-world data on oral semaglutide in Japanese patients with T2DM and its effects on cardiometabolic parameters. This was a single-center retrospective observational study. We examined changes in HbA1c and body weight (BW) and the rate of achieving HbA1c < 7% after 6 months of oral semaglutide treatment in Japanese patients with T2DM. Furthermore, we examined differences in the efficacy of oral semaglutide with multiple patient backgrounds. A total of 88 patients were included in this study. Overall, the mean (standard error of the mean) HbA1c at 6 months decreased by -1.24% (0.20%) from baseline, and BW at 6 months (n = 85) also decreased by -1.44 kg (0.26 kg) from baseline. The percentage of patients who achieved HbA1c < 7% changed significantly from 14% at baseline to 48%. HbA1c decreased from baseline regardless of age, sex, body mass index, chronic kidney disease, or diabetes duration. Additionally, alanine aminotransferase, total cholesterol, triglyceride, and non-high-density lipoprotein cholesterol were significantly reduced from baseline. Oral semaglutide may be an effective option for the intensification of therapy in Japanese patients with T2DM who have inadequate glycemic control with existing therapy. It may also reduce BW and improve cardiometabolic parameters.

Effectiveness and Safety of Once-Weekly Semaglutide in Japanese Patients with Type 2 Diabetes in Treatment Intensification: A Retrospective Observational Single-Center Study.

INTRODUCTION: Once-weekly (OW) glucagon-like peptide 1 receptor agonist (GLP-1RA) semaglutide has been shown to have a more potent glycated hemoglobin (HbA1c)-lowering effect than other oral hypoglycemic agents and existing GLP-1RAs in global randomized controlled trials. The study aim was to evaluate the safety and effectiveness of OW semaglutide in Japanese patients with type 2 diabetes mellitus (T2DM) in a real-world clinical setting and identify pre- and post-treatment predictors of good response. METHODS: We investigated the change in HbA1c, percentage of patients achieving < 7% HbA1c, and factors contributing to the effect 6 months after OW semaglutide use in Japanese patients with T2DM. We also examined differences in effectiveness between patients with different backgrounds. RESULTS: At baseline, the 77 patients had a mean baseline HbA1c of 8.1% ± 1.23%, 74% of the patients were injecting another GLP-1RA, and 42.9% of the patients were being treated with insulin. HbA1c decreased by 0.89% and by 0.66% in the other GLP-1RA users. The rate of achievement of < 7% HbA1c increased from 21% to 43%. There were no differences in effect by age, sex, or body mass index. Higher baseline HbA1c and shorter duration of diabetes were associated with greater HbA1c reduction. OW semaglutide was tolerable for the majority of our study population. CONCLUSION: This study provided real-world evidence showing that OW semaglutide significantly reduced HbA1c in Japanese patients with T2DM who had inadequate HbA1c control.

Loss of myeloid lipoprotein lipase exacerbates adipose tissue fibrosis with collagen VI deposition and hyperlipidemia in leptin-deficient obese mice.

During obesity, tissue macrophages increase in number and become proinflammatory, thereby contributing to metabolic dysfunction. Lipoprotein lipase (LPL), which hydrolyzes triglyceride in lipoproteins, is secreted by macrophages. However, the role of macrophage-derived LPL in adipose tissue remodeling and lipoprotein metabolism is largely unknown. To clarify these issues, we crossed leptin-deficient Lepob/ob mice with mice lacking the Lpl gene in myeloid cells (Lplm-/m-) to generate Lplm-/m-;Lepob/ob mice. We found the weight of perigonadal white adipose tissue (WAT) was increased in Lplm-/m-;Lepob/ob mice compared with Lepob/ob mice due to substantial accumulation of both adipose tissue macrophages and collagen that surrounded necrotic adipocytes. In the fibrotic epidydimal WAT of Lplm-/m-;Lepob/ob mice, we observed an increase in collagen VI and high mobility group box 1, while α-smooth muscle cell actin, a marker of myofibroblasts, was almost undetectable, suggesting that the adipocytes were the major source of the collagens. Furthermore, the adipose tissue macrophages from Lplm-/m-;Lepob/ob mice showed increased expression of genes related to fibrosis and inflammation. In addition, we determined Lplm-/m-;Lepob/ob mice were more hypertriglyceridemic than Lepob/ob mice. Lplm-/m-;Lepob/ob mice also showed slower weight gain than Lepob/ob mice, which was primarily due to reduced food intake. In conclusion, we discovered that the loss of myeloid Lpl led to extensive fibrosis of perigonadal WAT and hypertriglyceridemia. In addition to illustrating an important role of macrophage LPL in regulation of circulating triglyceride levels, these data show that macrophage LPL protects against fibrosis in obese adipose tissues.

Sex-specific Association of Primary Aldosteronism With Visceral Adiposity.

Context: The association between primary aldosteronism and obesity, especially its sex difference, remains unknown. Objective: To assess the association for each subtype of primary aldosteronism with obesity parameters including visceral adipose tissue and differences between sexes. Methods: In this case-control study, 4 normotensive controls were selected for each case with primary aldosteronism. Multivariable conditional logistic regression models were used to estimate the association between each type of primary aldosteronism and obesity indicators. We used a random forest to identify which visceral or subcutaneous tissue areas had a closer association with disease status. Results: The study subjects included 42 aldosterone-producing adenoma cases (22 women) and 68 idiopathic hyperaldosteronism cases (42 women). In multivariable conditional logistic regressions, aldosterone-producing adenoma was significantly associated with body mass index only in men (odds ratio [OR] [95% CI)], 4.62 [1.98-10.80] per 2.89 kg/m2) but not in women (OR [95% CI], 1.09 [0.69-1.72] per 3.93 kg/m2) compared with the matched controls, whereas idiopathic hyperaldosteronism was associated with body mass index in both men (OR [95% CI], 3.96 [2.03-7.73] per 3.75 kg/m2) and women (OR [95% CI], 2.65 [1.77-3.96] per 3.85 kg/m2) compared with the matched controls. In random forests, visceral adipose tissue areas were the better predictor of both aldosterone-producing adenoma and idiopathic hyperaldosteronism than subcutaneous adipose tissue. Conclusions: Aldosterone-producing adenoma cases were obese among men, but not among women. Idiopathic hyperaldosteronism cases were obese among both men and women. Visceral adipose tissue may contribute to the pathophysiology of primary aldosteronism.

AAA-ATPase valosin-containing protein binds the transcription factor SREBP1 and promotes its proteolytic activation by rhomboid protease RHBDL4.

Valosin-containing protein (VCP) is a member of AAA-ATPase superfamily involved in various cellular functions. To investigate the pathophysiological role of VCP in metabolic disorders, we generated knock-in mice bearing an A232E mutation in VCP, a known human VCP pathogenic variant. When heterozygous mutant mice (A232E/+) were fed a high-fat diet, we observed that fatty liver was ameliorated and the proteolytic processing of the transcription factor sterol regulatory element-binding protein 1 (SREBP1) was impaired. Further co-immunoprecipitation analysis in wildtype mice revealed interactions of VCP with SREBP1 and a rhomboid protease, RHBDL4, in the liver, and these interactions were attenuated in A232E/+ mice. Consistent with these results, we show that knockdown or chemical inhibition of VCP or RHBDL4 in human hepatocytes impaired the proteolytic processing of SREBP1. Finally, we found that knockdown of E3 ligases such as glycoprotein 78 and HMG-CoA reductase degradation protein 1 disrupted the interaction of VCP with SREBP1 and impaired the proteolytic processing of SREBP1. These results suggest that VCP recognizes ubiquitinylated SREBP1 and recruits it to RHBDL4 to promote its proteolytic processing. The present study reveals a novel proteolytic processing pathway of SREBP1 and may lead to development of new therapeutic strategies to treat fatty liver diseases.

A novel mechanism of imeglimin-mediated insulin secretion via the cADPR-TRP channel pathway.

AIMS/INTRODUCTION: Imeglimin is a novel oral hypoglycemic agent that improves blood glucose levels through multiple mechanisms of action including the enhancement of glucose-stimulated insulin secretion (GSIS), however, the details of this mechanism have not been clarified. In the process of GSIS, activation of the transient receptor potential melastatin 2 (TRPM2) channel, a type of non-selective cation channel (NSCCs) in ß-cells, promotes plasma membrane depolarization. The present study aimed to examine whether imeglimin potentiates GSIS via the TRPM2 channel in ß-cells. MATERIALS AND METHODS: Pancreatic islets were isolated by collagenase digestion from male wild-type and TRPM2-knockout (KO) mice. Insulin release and nicotinamide adenine dinucleotide (NAD+ ) production in islets were measured under static incubation. NSCC currents in mouse single ß-cells were measured by patch-clamp experiments. RESULTS: Batch-incubation studies showed that imeglimin enhanced GSIS at stimulatory 16.6 mM glucose, whereas it did not affect basal insulin levels at 2.8 mM glucose. Imeglimin increased the glucose-induced production of NAD+ , a precursor of cADPR, in islets and the insulinotropic effects of imeglimin were attenuated by a cADPR inhibitor 8-Br-cADPR. Furthermore, imeglimin increased NSCC current in ß-cells, and abolished this current in TRPM2-KO mice. Imeglimin did not potentiate GSIS in the TRPM2-KO islets, suggesting that imeglimin's increase of NSCC currents through the TRPM2 channel is causally implicated in its insulin releasing effects. CONCLUSIONS: Imeglimin may activate TRPM2 channels in ß-cells via the production of NAD+ /cADPR, leading to the potentiation of GSIS. Developing approaches to stimulate cADPR-TRPM2 signaling provides a potential therapeutic tool to treat type 2 diabetes.

Leptin sensitizing effect of 1,3-butanediol and its potential mechanism.

Leptin is an adipocyte-derived hormone that regulates appetite and energy expenditure via the hypothalamus. Since the majority of obese subjects are leptin resistant, leptin sensitizers, rather than leptin itself, are expected to be anti-obesity drugs. Endoplasmic reticulum (ER) stress in the hypothalamus plays a key role in the pathogenesis of leptin resistance. ATP-deficient cells are vulnerable to ER stress and ATP treatment protects cells against ER stress. Thus, we investigated the therapeutic effects of oral 1,3-butanediol (BD) administration, which increases plasma ß-hydroxybutyrate and hypothalamic ATP concentrations, in diet induced obese (DIO) mice with leptin resistance. BD treatment effectively decreased food intake and body weight in DIO mice. In contrast, BD treatment had no effect in leptin deficient ob/ob mice. Co-administration experiment demonstrated that BD treatment sensitizes leptin action in both DIO and ob/ob mice. We also demonstrated that BD treatment attenuates ER stress and leptin resistance at the hypothalamus level. This is the first report to confirm the leptin sensitizing effect of BD treatment in leptin resistant DIO mice. The present study provides collateral evidence suggesting that the effect of BD treatment is mediated by the elevation of hypothalamic ATP concentration. Ketone bodies and hypothalamic ATP are the potential target for the treatment of obesity and its complications.

Normal plasma apoB48 despite the virtual absence of apoB100 in a compound heterozygote with novel mutations in the MTTP gene.

"Normotriglyceridemic abetalipoproteinemia (ABL)" was originally described as a clinical entity distinct from either ABL or hypobetalipoproteinemia. Subsequent studies identified mutations in APOB gene which encoded truncated apoB longer than apoB48. Therefore, "Normotriglyceridemic ABL" can be a subtype of homozygous familial hypobetalipoproteinemia. Here, we report an atypical female case of ABL who was initially diagnosed with "normotriglyceridemic ABL", because she had normal plasma apoB48 despite the virtual absence of apoB100 and low plasma TG level. Next generation sequencing revealed that she was a compound heterozygote of two novel MTTP mutations: nonsense (p.Q272X) and missense (p.G709R). We speculate that p.G709R might confer residual triglyceride transfer activity of MTTP preferentially in the intestinal epithelium to the hepatocytes, allowing production of apoB48. Together, "normotriglyceridemic ABL" may be a heterogenous disorder which is caused by specific mutations in either APOB or MTTP gene.

A case of insulinoma with hypoglycemia that was better managed with lanreotide than octreotide.

Long-acting somatostatin analogs, including lanreotide slow release (LAN-SR) and octreotide long-acting release (OCT-LAR), can improve hypoglycemia in insulinoma. LAN-SR may be more beneficial in some patients with insulinoma than OCT-LAR.

A novel SOX10 nonsense mutation in a patient with Kallmann syndrome and Waardenburg syndrome.

SUMMARY: The underlying genetic drivers of Kallmann syndrome, a rare genetic disorder characterized by anosmia and hypogonadotropic hypogonadism due to impairment in the development of olfactory axons and in the migration of gonadotropin-releasing hormone (GNRH)-producing neurons during embryonic development, remain largely unknown. SOX10, a key transcription factor involved in the development of neural crest cells and established as one of the causative genes of Waardenburg syndrome, has been shown to be a causative gene of Kallmann syndrome. A 17-year-old male patient, who was diagnosed with Waardenburg syndrome on the basis of a hearing impairment and hypopigmented iris at childhood, was referred to our department because of anosmia and delayed puberty. As clinical examination revealed an aplastic olfactory bulb and hypogonadotropic hypogonadism, we diagnosed him as having Kallmann syndrome. Incidentally, we elucidated that he also presented with subclinical hypothyroidism without evidence of autoimmune thyroiditis. Direct sequence analysis detected a nonsense SOX10 mutation (c.373C>T, p.Glu125X) in this patient. Since this nonsense mutation has never been published as a germline variant, the SOX10 substitution is a novel mutation that results in Kallmann syndrome and Waardenburg syndrome. This case substantiates the significance of SOX10 as a genetic cause of Kallmann syndrome and Waardenburg syndrome, which possibly share a common pathway in the development of neural crest cells. LEARNING POINTS: Kallmann syndrome and Waardenburg syndrome possibly share a common pathway during neural crest cell development. SOX10, a key transcription factor involved in the development of neural crest cells, is a common causative gene of Kallmann syndrome and Waardenburg syndrome. Careful evaluation about various phenotypic features may reveal the unknown genetic drivers of Kallmann syndrome.

ß-Cell-Specific Deletion of HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) Reductase Causes Overt Diabetes due to Reduction of ß-Cell Mass and Impaired Insulin Secretion.

Inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), statins, which are used to prevent cardiovascular diseases, are associated with a modest increase in the risk of new-onset diabetes. To investigate the role of HMGCR in the development of ß-cells and glucose homeostasis, we deleted Hmgcr in a ß-cell-specific manner by using the Cre-loxP technique. Mice lacking Hmgcr in ß-cells (ß-KO) exhibited hypoinsulinemic hyperglycemia as early as postnatal day 9 (P9) due to decreases in both ß-cell mass and insulin secretion. Ki67-positive cells were reduced in ß-KO mice at P9; thus, ß-cell mass reduction was caused by proliferation disorder immediately after birth. The mRNA expression of neurogenin3 (Ngn3), which is transiently expressed in endocrine progenitors of the embryonic pancreas, was maintained despite a striking reduction in the expression of ß-cell-associated genes, such as insulin, pancreatic and duodenal homeobox 1 (Pdx1), and MAF BZIP transcription factor A (Mafa) in the islets from ß-KO mice. Histological analyses revealed dysmorphic islets with markedly reduced numbers of ß-cells, some of which were also positive for glucagon. In conclusion, HMGCR plays critical roles not only in insulin secretion but also in the development of ß-cells in mice.

Esterification of 4ß-hydroxycholesterol and other oxysterols in human plasma occurs independently of LCAT.

The acyltransferase LCAT mediates FA esterification of plasma cholesterol. In vitro studies have shown that LCAT also FA-esterifies several oxysterols, but in vivo evidence is lacking. Here, we measured both free and FA-esterified forms of sterols in 206 healthy volunteers and 8 individuals with genetic LCAT deficiency, including familial LCAT deficiency (FLD) and fish-eye disease (FED). In the healthy volunteers, the mean values of the ester-to-total molar ratios of the following sterols varied: 4ß-hydroxycholesterol (4ßHC), 0.38; 5,6α-epoxycholesterol (5,6αEC), 0.46; 5,6ß-epoxycholesterol (5,6ßEC), 0.51; cholesterol, 0.70; cholestane-3ß,5α,6ß-triol (CT), 0.70; 7-ketocholesterol (7KC), 0.75; 24S-hydroxycholesterol (24SHC), 0.80; 25-hydroxycholesterol (25HC), 0.81; 27-hydroxycholesterol (27HC), 0.86; and 7α-hydroxycholesterol (7αHC), 0.89. In the individuals with LCAT deficiency, the plasma levels of the FA-esterified forms of cholesterol, 5,6αEC, 5,6ßEC, CT, 7αHC, 7KC, 24SHC, 25HC, and 27HC, were significantly lower than those in the healthy volunteers. The individuals with FLD had significantly lower FA-esterified forms of 7αHC, 24SHC, and 27HC than those with FED. It is of note that, even in the three FLD individuals with negligible plasma cholesteryl ester, substantial amounts of the FA-esterified forms of 4ßHC, 5,6αEC, 7αHC, 7KC, and 27HC were present. We conclude that LCAT has a major role in the FA esterification of many plasma oxysterols but contributes little to the FA esterification of 4ßHC. Substantial FA esterification of 4ßHC, 5,6αEC, 7αHC, 7KC, and 27HC is independent of LCAT.

Peripheral circadian rhythms in the liver and white adipose tissue of mice are attenuated by constant light and restored by time-restricted feeding.

Disturbance of circadian rhythms underlies various metabolic diseases. Constant light exposure (LL) is known to disrupt both central and peripheral circadian rhythms. Here, we attempted to determine whether the effects of LL are different between various peripheral tissues and whether time-restricted feeding restores the circadian rhythms especially in white adipose tissue (WAT). Six-week-old mice were subjected to three feeding regimes: ad libitum feeding under light/dark phase (LD), ad libitum feeding under LL cycle, and restricted feeding at night-time under LL cycle with a normal chow. After 3 weeks, we compared body weight, food intake, plasma levels of lipids and glucose, and the expression patterns of the clock genes and the genes involved in lipid metabolism in the liver and WAT. The mice kept under LL with or without time-restricted feeding were 5.2% heavier (p<0.001, n = 16) than the mice kept under LD even though the food intakes of the two groups were the same. Food intake occurred mostly in the dark phase. LL disrupted this pattern, causing disruptions in circadian rhythms of plasma levels of triglycerides (TG) and glucose. Time-restricted feeding partially restored the rhythms. LL eliminated the circadian rhythms of the expression of the clock genes as well as most of the genes involved in lipid metabolism in both liver and WAT. More notably, LL markedly decreased not only the amplitude but also the average levels of the expression of the genes in the liver, but not in the WAT, suggesting that transcription in the liver is sensitive to constant light exposure. Time-restricted feeding restored the circadian rhythms of most of the genes to various degrees in both liver and WAT. In conclusion, LL disrupted the peripheral circadian rhythms more severely in liver than in WAT. Time-restricted feeding restored the circadian rhythms in both tissues.

Long-term efficacy of the sodium-glucose cotransporter 2 inhibitor, ipragliflozin, in a case of type A insulin resistance syndrome.

Type A insulin resistance (IR) syndrome is a severe IR form caused by insulin receptor (INSR) gene defects. Antidiabetic drugs, including high-dose insulin and insulin-sensitizing agents, often fail to control associated hyperglycemia. Therapy with recombinant human insulin-like growth factor 1 can be more effective, but it is expensive. We report a case of type A IR syndrome with an in-frame INSR heterozygous deletion (ΔLeu999) that was treated with a combination of conventional therapy and ipragliflozin, a sodium-glucose cotransporter 2 inhibitor. Treatment reduced hemoglobin A1c levels (10.0-7.5%) and induced weight loss (54.4-52.0 kg) within 2 months, and the effects were sustained for >3 years. Sodium-glucose cotransporter 2 inhibitors might be useful to normalize blood glucose in type A IR syndrome by reducing bodyweight and ameliorating glucotoxicity.

Myeloid HMG-CoA Reductase Determines Adipose Tissue Inflammation, Insulin Resistance, and Hepatic Steatosis in Diet-Induced Obese Mice.

Adipose tissue macrophages (ATMs) are involved in the development of insulin resistance in obesity. We have recently shown that myeloid cell-specific reduction of HMG-CoA reductase (Hmgcr m-/m- ), which is the rate-limiting enzyme in cholesterol biosynthesis, protects against atherosclerosis by inhibiting macrophage migration in mice. We hypothesized that ATMs are harder to accumulate in Hmgcr m-/m- mice than in control Hmgcr fl/fl mice in the setting of obesity. To test this hypothesis, we fed Hmgcr m-/m- and Hmgcr fl/fl mice a high-fat diet (HFD) for 24 weeks and compared plasma glucose metabolism as well as insulin signaling and histology between the two groups. Myeloid cell-specific reduction of Hmgcr improved glucose tolerance and insulin sensitivity without altering body weight in the HFD-induced obese mice. The improvement was due to a decrease in the number of ATMs. The ATMs were reduced by decreased recruitment of macrophages as a result of their impaired chemotactic activity. These changes were associated with decreased expression of proinflammatory cytokines in adipose tissues. Myeloid cell-specific reduction of Hmgcr also attenuated hepatic steatosis. In conclusion, reducing myeloid HMGCR may be a promising strategy to improve insulin resistance and hepatic steatosis in obesity.

Loss of ACAT1 Attenuates Atherosclerosis Aggravated by Loss of NCEH1 in Bone Marrow-Derived Cells.

AIM: Acyl-CoA cholesterol acyltransferase 1 (ACAT1) esterifies free cholesterol to cholesteryl esters (CE), which are subsequently hydrolyzed by neutral cholesterol ester hydrolase 1 (NCEH1). The elimination of ACAT1 in vitro reduces the amounts of CE accumulated in Nceh1-deficient macrophages. The present study aimed at examining whether the loss of ACAT1 attenuates atherosclerosis which is aggravated by the loss of NCEH1 in vivo. METHODS: Low density lipoprotein receptor (Ldlr)-deficient mice were transplanted with bone marrow from wild-type mice and mice lacking ACAT1, NCEH1, or both. The four types of mice were fed a high-cholesterol diet and, then, were examined for atherosclerosis. RESULTS: The cross-sectional lesion size of the recipients of Nceh1-deficient bone marrow was 1.6-fold larger than that of the wild-type bone marrow. The lesions of the recipients of Nceh1-deficient bone marrow were enriched with MOMA2-positive macrophages compared with the lesions of the recipients of the wild-type bone marrow. The size and the macrophage content of the lesions of the recipients of bone marrow lacking both ACAT1 and NCEH1 were significantly smaller than the recipients of the Nceh1-deficient bone marrow, indicating that the loss of ACAT1 decreases the excess CE in the Nceh1-deficient lesions. The collagen-rich and/or mucin-rich areas and en face lesion size were enlarged in the recipients of the Acat1－/－ bone marrow compared with those of the recipients of the WT bone marrow. CONCLUSION: The loss of ACAT1 in bone marrow-derived cells attenuates atherosclerosis, which is aggravated by the loss of NCEH1, corroborating the in vitro functions of ACAT1 (formation of CE) and NCEH1 (hydrolysis of CE).

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.