松村 貴由

IMPORTANCE: Vasospastic angina (VSA) is vasospasm of the coronary artery and is particularly prevalent in East Asian populations. However, the specific genetic architecture for VSA at genome-wide levels is not fully understood. OBJECTIVE: To identify genetic factors associated with VSA. DESIGN, SETTING, AND PARTICIPANTS: This was a case-control genome-wide association study of VSA. Data from Biobank Japan (BBJ; enrolled patients from 2002-2008 and 2013-2018) were used, and controls without coronary artery disease (CAD) were enrolled. Patients from the BBJ were genotyped using arrays or a set of arrays. Patients recruited between 2002 and 2005 were classified within the first dataset, and those recruited between 2006 and 2008 were classified within the second dataset. To replicate the genome-wide association study in the first and second datasets, VSA cases and control samples from the latest patients in the BBJ recruited between 2013 and 2018 were analyzed in a third dataset. EXPOSURES: Single-nucleotide variants associated with VSA. MAIN OUTCOMES AND MEASURES: Cases with VSA and controls without CAD. RESULTS: A total of 5720 cases (mean [SD] age, 67 [10] years; 3672 male [64.2%]) and 153 864 controls (mean [SD] age, 62 [15] years; 77 362 male [50.3%]) in 3 datasets were included in this study. The variants at the RNF213 locus showed the strongest association with VSA across the 3 datasets (odds ratio [OR], 2.34; 95% CI, 1.99-2.74; P = 4.4 × 10-25). Additionally, rs112735431, an Asian-specific rare deleterious variant (p.Arg4810Lys) experimentally shown to be associated with reduced angiogenesis and a well-known causal risk for Moyamoya disease was the most promising candidate for a causal variant explaining the association. The effect size of rs112735431 on VSA was distinct from that of other CADs. Furthermore, homozygous carriers of rs112735431 showed an association with VSA characterized by a large effect estimate (OR, 18.34; 95% CI, 5.15-65.22; P = 7.0 × 10-6), deviating from the additive model (OR, 4.35; 95% CI, 1.18-16.05; P = .03). Stratified analyses revealed that rs112735431 exhibited a stronger association in males (χ21 = 7.24; P = .007) and a younger age group (OR, 3.06; 95% CI, 2.24-4.19), corresponding to the epidemiologic features of VSA. In the registry, carriers without CAD of the risk allele rs112735431 had a strikingly high mortality rate due to acute myocardial infarction during the follow-up period (hazard ratio, 2.71; 95% CI, 1.57-4.65; P = 3.3 × 10-4). As previously reported, a possible overlap between VSA and Moyamoya disease was not found. CONCLUSIONS AND RELEVANCE: Results of this study suggest that vascular cell dysfunction mediated by variants in the RNF213 locus may promote coronary vasospasm, and the presence of the risk allele could serve as a predictive factor for the prognosis.

The genetic lesions that drive acute megakaryoblastic leukemia (AMKL) have not been fully elucidated. To search for genetic alterations in AMKL, we performed targeted deep sequencing in 34 AMKL patient samples and 8 AMKL cell lines and detected frequent genetic mutations in the NOTCH pathway in addition to previously reported alterations in GATA-1 and the JAK-STAT pathway. Pharmacological and genetic NOTCH activation, but not inhibition, significantly suppressed AMKL cell proliferation in both in vitro and in vivo assays employing a patient-derived xenograft model. These results suggest that NOTCH inactivation underlies AMKL leukemogenesis. and NOTCH activation holds the potential for therapeutic application in AMKL.

Recent evidence indicates ferroptosis is implicated in the pathophysiology of various liver diseases; however, the organ-specific regulation mechanism is poorly understood. Here, we demonstrate 7-dehydrocholesterol reductase (DHCR7), the terminal enzyme of cholesterol biosynthesis, as a regulator of ferroptosis in hepatocytes. Genetic and pharmacological inhibition (with AY9944) of DHCR7 suppress ferroptosis in human hepatocellular carcinoma Huh-7 cells. DHCR7 inhibition increases its substrate, 7-dehydrocholesterol (7-DHC). Furthermore, exogenous 7-DHC supplementation using hydroxypropyl β-cyclodextrin suppresses ferroptosis. A 7-DHC-derived oxysterol metabolite, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), is increased by the ferroptosis-inducer RSL-3 in DHCR7-deficient cells, suggesting that the ferroptosis-suppressive effect of DHCR7 inhibition is associated with the oxidation of 7-DHC. Electron spin resonance analysis reveals that 7-DHC functions as a radical trapping agent, thus protecting cells from ferroptosis. We further show that AY9944 inhibits hepatic ischemia-reperfusion injury, and genetic ablation of Dhcr7 prevents acetaminophen-induced acute liver failure in mice. These findings provide new insights into the regulatory mechanism of liver ferroptosis and suggest a potential therapeutic option for ferroptosis-related liver diseases.

Menkes disease is an X-linked disorder of copper metabolism caused by mutations in the ATP7A gene, and female carriers are usually asymptomatic. We describe a 7-month-old female patient with severe intellectual disability, epilepsy, and low levels of serum copper and ceruloplasmin. While heterozygous deletion of exons 16 and 17 of the ATP7A gene was detected in the proband, her mother, and her grandmother, only the proband suffered from Menkes disease clinically. Intriguingly, X chromosome inactivation (XCI) analysis demonstrated that the grandmother and the mother showed skewing of XCI toward the allele with the ATP7A deletion and that the proband had extremely skewed XCI toward the normal allele, resulting in exclusive expression of the pathogenic ATP7A mRNA transcripts. Expression bias analysis and recombination mapping of the X chromosome by the combination of whole genome and RNA sequencing demonstrated that meiotic recombination occurred at Xp21-p22 and Xq26-q28. Assuming that a genetic factor on the X chromosome enhanced or suppressed XCI of its allele, the factor must be on either of the two distal regions derived from her grandfather. Although we were unable to fully uncover the molecular mechanism, we concluded that unfavorable switching of skewed XCI caused Menkes disease in the proband.

Caspase-11 is an inflammatory caspase that triggers an inflammatory response by regulating non-canonical NLRP3 inflammasome activation. Although the deficiency of both caspase-11 and caspase-1, another inflammatory caspase that functions as an executor of the inflammasome, prevents the development of atherosclerosis, the effect of caspase-11 deficiency alone on the development of atherosclerosis has not been fully evaluated. In the present study, we found that caspase-11 deficiency prevented the formation of the necrotic core, whereas it did not affect the development of atherosclerosis in Apoe-deficient mice. Notably, the infiltration of neutrophils into atherosclerotic lesions was attenuated by caspase-11 deficiency. RNA-seq analysis of stage-dependent expression of atherosclerotic lesions revealed that both upregulations of caspase-11 and neutrophil migration are common features of advanced atherosclerotic lesions. Furthermore, similar expression profiles were observed in unstable human plaque. These data suggest that caspase-11 regulates neutrophil recruitment and plaque destabilization in advanced atherosclerotic lesions.

Sepsis is a life-threatening syndrome, and its associated mortality is increased when cardiac dysfunction and damage (septic cardiomyopathy [SCM]) occur. Although inflammation is involved in the pathophysiology of SCM, the mechanism of how inflammation induces SCM in vivo has remained obscure. NLRP3 inflammasome is a critical component of the innate immune system that activates caspase-1 (Casp1) and causes the maturation of IL-1β and IL-18 as well as the processing of gasdermin D (GSDMD). Here, we investigated the role of the NLRP3 inflammasome in a murine model of lipopolysaccharide (LPS)-induced SCM. LPS injection induced cardiac dysfunction, damage, and lethality, which was significantly prevented in NLRP3-/- mice, compared to wild-type (WT) mice. LPS injection upregulated mRNA levels of inflammatory cytokines (Il6, Tnfa, and Ifng) in the heart, liver, and spleen of WT mice, and this upregulation was prevented in NLRP3-/- mice. LPS injection increased plasma levels of inflammatory cytokines (IL-1β, IL-18, and TNF-α) in WT mice, and this increase was markedly inhibited in NLRP3-/- mice. LPS-induced SCM was also prevented in Casp1/11-/- mice, but not in Casp11mt, IL-1β-/-, IL-1α-/-, or GSDMD-/- mice. Notably, LPS-induced SCM was apparently prevented in IL-1β-/- mice transduced with adeno-associated virus vector expressing IL-18 binding protein (IL-18BP). Furthermore, splenectomy, irradiation, or macrophage depletion alleviated LPS-induced SCM. Our findings demonstrate that the cross-regulation of NLRP3 inflammasome-driven IL-1β and IL-18 contributes to the pathophysiology of SCM and provide new insights into the mechanism underlying the pathogenesis of SCM.

Abstract The transcription factor MYB is a crucial regulator of hematopoietic stem and progenitor cells. However, the nature of lineage-specific enhancer usage of the Myb gene is largely unknown. We identify the Myb −68 enhancer, a regulatory element which marks basophils and mast cells. Using the Myb −68 enhancer activity, we show a population of granulocyte-macrophage progenitors with higher potential to differentiate into basophils and mast cells. Single cell RNA-seq demonstrates the differentiation trajectory is continuous from progenitors to mature basophils in vivo, characterizes bone marrow cells with a gene signature of mast cells, and identifies LILRB4 as a surface marker of basophil maturation. Together, our study leads to a better understanding of how MYB expression is regulated in a lineage-associated manner, and also shows how a combination of lineage-related reporter mice and single-cell transcriptomics can overcome the rarity of target cells and enhance our understanding of gene expression programs that control cell differentiation in vivo.

Cryopyrin-associated periodic syndrome (CAPS) is an autoinflammatory syndrome caused by mutations of NLRP3 gene encoding cryopyrin. Familial cold autoinflammatory syndrome, the mildest form of CAPS, is characterized by cold-induced inflammation induced by the overproduction of IL-1β. However, the molecular mechanism of how mutated NLRP3 causes inflammasome activation in CAPS remains unclear. Here, we found that CAPS-associated NLRP3 mutants form cryo-sensitive aggregates that function as a scaffold for inflammasome activation. Cold exposure promoted inflammasome assembly and subsequent IL-1β release triggered by mutated NLRP3. While K⁺ efflux was dispensable, Ca²⁺ was necessary for mutated NLRP3-mediated inflammasome assembly. Notably, Ca²⁺ influx was induced during mutated NLRP3-mediated inflammasome assembly. Furthermore, caspase-1 inhibition prevented Ca²⁺ influx and inflammasome assembly induced by the mutated NLRP3, suggesting a feed-forward Ca²⁺ influx loop triggered by mutated NLRP3. Thus, the mutated NLRP3 forms cryo-sensitive aggregates to promote inflammasome assembly distinct from canonical NLRP3 inflammasome activation.

Adult erythropoiesis entails a series of well-coordinated events that produce mature red blood cells. One of such events is the mitochondria clearance that occurs cell-autonomously via autophagy-dependent mechanisms. Interestingly, recent studies have shown mitochondria transfer activities between various cell types. In the context of erythropoiesis, macrophages are known to interact closely with the early stages of erythroblasts to provide a specialized niche, termed erythroblastic islands (EBI). However, whether mitochondria transfer can occur in the EBI niche has not been explored. Here, we report that mitochondria transfer in the EBI niche occurs in vivo. We observed mitochondria transfer activities from the early stages of erythroblasts to macrophages in the reconstituted in vitro murine EBI via different modes, including tunnelling nanotubes (TNT). Moreover, we demonstrated that Wiskott-Aldrich syndrome protein (WASp) in macrophages mediates TNT formation and mitochondria transfer via the modulation of F-actin filamentation, thus promoting mitochondria clearance from erythroid cells, to potentially enhance their differentiation. Taken together, our findings provide novel insight into the mitochondria clearance machineries that mediate erythroid maturation.

Abstract Hematopoietic stem cells (HSC) rarely divide, rest in quiescence, and proliferate only upon stress hematopoiesis. The cytokine thrombopoietin (Thpo) has been perplexingly described to induce quiescence and promote self-renewal divisions in HSCs. To clarify the contradictory effect of Thpo, we conducted a detailed analysis on conventional (Thpo−/−) and liver-specific (Thpofl/fl;AlbCre+/−) Thpo-deletion models. Thpo−/− HSCs exhibited profound loss of quiescence, impaired cell cycle progression, and increased apoptosis. Thpo−/− HSCs also exhibited diminished mitochondrial mass and impaired mitochondrial bioenergetics. Abnormal HSC phenotypes in Thpo−/− mice were reversible after HSC transplantation into wild-type recipients. Moreover, Thpo−/− HSCs acquired quiescence with extended administration of a Thpo receptor agonist, romiplostim, and were prone to subsequent stem cell exhaustion during competitive bone marrow transplantation. Thpofl/fl;AlbCre+/− HSCs exhibited similar stem cell phenotypes but to a lesser degree compared with Thpo−/− HSCs. HSCs that survive Thpo deficiency acquire quiescence in a dose-dependent manner through the modification of their metabolic state.

Abstract Hematopoietic stem cells (HSCs) undergo self-renewal or differentiation to sustain lifelong hematopoiesis. HSCs are preserved in quiescence with low mitochondrial activity. Recent studies indicate that autophagy contributes to HSC quiescence through suppressing mitochondrial metabolism. However, it remains unclear whether autophagy is involved in the regulation of neonatal HSCs, which proliferate actively. In this study, we clarified the role of autophagy in neonatal HSCs using 2 types of autophagy-related gene 7 (Atg7)-conditional knockout mice: Mx1-Cre inducible system and Vav-Cre system. Atg7-deficient HSCs exhibited excess cell divisions with enhanced mitochondrial metabolism, leading to bone marrow failure at adult stage. However, Atg7 deficiency minimally affected hematopoiesis and metabolic state in HSCs at neonatal stage. In addition, Atg7-deficient neonatal HSCs exhibited long-term reconstructing activity, equivalent to wild-type neonatal HSCs. Taken together, autophagy is dispensable for stem cell function and hematopoietic homeostasis in neonates and provide a novel aspect into the role of autophagy in the HSC regulation.

Abstract RUNX1 is among the most frequently mutated genes in human leukemia, and the loss or dominant-negative suppression of RUNX1 function is found in myelodysplastic syndrome and acute myeloid leukemia (AML). How posttranslational modifications (PTMs) of RUNX1 affect its in vivo function, however, and whether PTM dysregulation of RUNX1 can cause leukemia are largely unknown. We performed targeted deep sequencing on a family with 3 occurrences of AML and identified a novel RUNX1 mutation, R237K. The mutated R237 residue is a methylation site by protein arginine methyltransferase 1, and loss of methylation reportedly impairs the transcriptional activity of RUNX1 in vitro. To explore the biologic significance of RUNX1 methylation in vivo, we used RUNX1 R233K/R237K double-mutant mice, in which 2 arginine-to-lysine mutations precluded RUNX1 methylation. Genetic ablation of RUNX1 methylation led to loss of quiescence and expansion of hematopoietic stem cells (HSCs), and it changed the genomic and epigenomic signatures of phenotypic HSCs to a poised progenitor state. Furthermore, loss of RUNX1 R233/R237 methylation suppressed endoplasmic reticulum stress–induced unfolded protein response genes, including Atf4, Ddit3, and Gadd34; the radiation-induced p53 downstream genes Bbc3, Pmaip1, and Cdkn1a; and subsequent apoptosis in HSCs. Mechanistically, activating transcription factor 4 was identified as a direct transcriptional target of RUNX1. Collectively, defects in RUNX1 methylation in HSCs confer resistance to apoptosis and survival advantage under stress conditions, a hallmark of a preleukemic clone that may predispose affected individuals to leukemia. Our study will lead to a better understanding of how dysregulation of PTMs can contribute to leukemogenesis.

Key Points HSCs can be separated based on high or low mitochondrial mass. Higher mitochondrial mass is associated with quiescence and greater reconstitution capacity of HSCs.

Significance Takayasu arteritis (TAK) is a systemic vasculitis with unknown etiology. We identified four unreported susceptibility genes to TAK through genome-wide association studies. We successfully fine-mapped HLA associations and showed that HLA-G is associated with TAK in addition to HLA-B*52. The association between PTK2B and TAK could be explained by expression regulation of PTK2B. We showed an epistasis effect of LILR3A, one of the four genes, with HLA-B52 on TAK susceptibility. Enhancer enrichment analysis of significant non-HLA markers showed natural killer cells as important cells in TAK. Not only the associations in the HLA region but also nonsignificant associations from GWAS suggest the involvement of NK cells. These findings would lead to a better understanding of TAK.

Background: Takayasu arteritis (TAK) is an autoimmune systemic arteritis of unknown pathogenesis. Genome-wide association studies revealed that single-nucleotide polymorphisms in the MLX gene encoding the MLX (Max-like protein X) transcription factor are significantly associated with TAK in Japanese patients. MLX single-nucleotide polymorphism rs665268 is a missense mutation causing the Q139R substitution in the DNA-binding site of MLX. Methods: To elucidate the hypothesis that the single-nucleotide polymorphism of the MLX gene plays a critical role in the development of TAK, we conducted clinical and laboratory analyses. Results: We show that rs665268 significantly correlated with the severity of TAK, including the number of arterial lesions and morbidity of aortic regurgitation; the latter may be attributed to the fact that MLX mRNA expression was mostly detected in the aortic valve. Furthermore, the Q139R mutation caused structural changes in MLX, which resulted in enhanced formation of a heterodimer with MondoA, upregulation of TXNIP (thioredoxin-interacting protein) expression, and increase in the activity of the NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome and cellular oxidative stress. Furthermore, autophagy, which negatively regulates inflammasome activation, was suppressed by the Q139R mutation in MLX. The MLX-Q139R mutant significantly induced macrophage proliferation and macrophage–endothelium interaction, which was abolished by the treatment with SBI-477, an inhibitor of MondoA nuclear translocation. Our findings suggest that the Q139R substitution in MLX plays a crucial role in the pathogenesis of TAK. Conclusions: MLX-Q139R mutation plays a crucial role in the pathogenesis of TAK through promoting inflammasome formation.

Most of the hematopoietic stem cells (HSCs) within the bone marrow (BM) show quiescent state with a low mitochondrial membrane potential (ΔΨm). In contrast, upon stress hematopoiesis, HSCs actively start to divide. However, the underlying mechanism for the initiation of HSC division still remains unclear. To elucidate the mechanism underlying the transition of cell cycle state in HSCs, we analyzed the change of mitochondria in HSCs after BM suppression induced by 5-fluoruracil (5-FU). We found that HSCs initiate cell division after exhibiting enhanced ΔΨm as a result of increased intracellular Ca2+ level. Although further activation of Ca2+–mitochondria pathway led to loss of HSCs after cell division, the appropriate suppression of intracellular Ca2+ level by exogenous adenosine or Nifedipine, a Ca2+ channel blocker, prolonged cell division interval in HSCs, and simultaneously achieved both cell division and HSC maintenance. Collectively, our results indicate that the Ca2+–mitochondria pathway induces HSC division critically to determine HSC cell fate.

Takayasu arteritis (TAK) is an acute and chronic vasculitis of unknown etiology. Recently, our group reported that SNP rs6871626 in the IL12B region had significant association with disease susceptibility to TAK. However, association of the SNP with clinical characteristics of TAK has yet to be determined. Therefore, we assessed whether this SNP was associated with TAK disease severity as represented by early onset and/or refractoriness to medical therapy. A total of 90 patients were genotyped for rs6871626 and their clinical charts were reviewed retrospectively. By examining the relationship between genotype and clinical profiles of patients, we found a strong association between the number of risk alleles and the frequency of severe cases as defined by (1) age at onset <20 years old, (2) steroid resistance, and/or (3) a relapse of disease [p = 0.03; odds ratio 3.75 (95 % confidence interval 1.13-13.5)]. Thus, our study points to potential diagnostic use of SNP rs6871626 for predicting disease severity of TAK, with the goal of genotyping-oriented therapy in the near future.

RUNX1/AML1 is among the most commonly mutated genes in human leukemia. Haploinsufficiency of RUNX1 causes familial platelet disorder with predisposition to myeloid malignancies (FPD/MM). However, the molecular mechanism of FPD/MM remains unknown. Here we show that murine Runx1(+/-) hematopoietic cells are hypersensitive to granulocyte colony-stimulating factor (G-CSF), leading to enhanced expansion and mobilization of stem/progenitor cells and myeloid differentiation block. Upon G-CSF stimulation, Runx1(+/-) cells exhibited a more pronounced phosphorylation of STAT3 as compared with Runx1(+/+) cells, which may be due to reduced expression of Pias3, a key negative regulator of STAT3 signaling, and reduced physical sequestration of STAT3 by RUNX1. Most importantly, blood cells from a FPD patient with RUNX1 mutation exhibited similar G-CSF hypersensitivity. Taken together, Runx1 haploinsufficiency appears to predispose FPD patients to MM by expanding the pool of stem/progenitor cells and blocking myeloid differentiation in response to G-CSF.

Objective. Takayasu arteritis (TAK) is a systemic vasculitis affecting large arteries and large branches of the aorta. Ulcerative colitis (UC) is a prevalent autoimmune colitis. Since TAK and UC share HLA-B*52:01 and IL12B as genetic determinants, and since there are case reports of the co-occurrence of these diseases, we hypothesized that UC is a common complication of TAK. We undertook this study to perform a large-scale analysis of TAK, both to evaluate the prevalence of concurrent cases of TAK and UC and to identify and estimate susceptibility genes shared between the 2 diseases. Methods. We analyzed a total of 470 consecutive patients with TAK from 14 institutions. We characterized patients with TAK and UC by analyzing clinical manifestations and genetic components. Genetic overlapping of TAK and UC was evaluated with the use of UC susceptibility single-nucleotide polymorphisms by comparing risk directions and effect sizes between susceptibility to the 2 diseases. Results. Thirty of 470 patients with TAK had UC (6.4% [95% confidence interval 4.3-9.0]). This percentage was strikingly higher than that expected from the prevalence of UC in Japan. Patients with TAK complicated with UC developed TAK at an earlier stage of life (P=0.0070) and showed significant enrichment of HLA-B*52:01 compared to TAK patients without UC (P=1.0 x 10(-5)) (odds ratio 12.14 [95% confidence interval 2.96-107.23]). The 110 non-HLA markers of susceptibility to UC significantly displayed common risk directions with susceptibility to TAK (P=0.0054) and showed significant departure of permutation P values from expected P values (P &lt; 1.0 x 10(-10)). Conclusion. UC is a major complication of TAK. These 2 diseases share a significant proportion of their genetic background, and HLA-B*52:01 may play a central role in their co-occurrence.

There has been considerable interest in identifying a cis-regulatory element that targets gene expression to stem cells. Such an element, termed stem cell enhancer, holds the promise of providing important insights into the transcriptional programs responsible for inherent stem cell-specific properties such as self-renewal capacity. The element also serves as a molecular handle for stem cell-specific marking, transgenesis and gene targeting, thereby becoming invaluable to stem cell research. A series of candidate enhancers have been identified for hematopoietic stem cells (HSCs). This review summarizes currently known HSC enhancers with emphasis on an intronic enhancer in the Runx1 gene which is critical for the generation and maintenance of HSCs. The element, named eR1 (+24m), is active specifically in HSCs, but not in progenitors, and is hence the most definitive HSC enhancer.

Interrupted inferior vena cava (IVC) with azygos continuation is a rare congenital anomaly, and is frequently associated with other cardiovascular malformations and situs anomalies, such as left isomerism. These patients usually develop deep vein thrombosis (DVT), and asymptomatic patients above 60 years of age are very rare. Here we report a case of interrupted IVC which we diagnosed in a 72-year-old woman. She was admitted to our hospital suffering from heart failure and supraventricular tachycardia. Echocardiography detected secundum atrial septal defect (ASD). An abnormal paravertebral pleural line on the chest X-rays indicated the existence of venous anomaly. Anatomical images obtained by Multidetector Computed Tomography (MDCT) helped us to successfully perform right heart catheterization procedures through azygos continuation including blood sampling from pulmonary veins. Even in elderly patients, a careful examination of chest X-rays can indicate undiagnosed venous anomalies; thus, it is critically important before planning surgical or interventional procedures.

Immunoglobulin G4 (IgG4)-related systemic disease was first recognized as a clinicopathological entity about 10 years ago, and since then, it has attracted growing attention. It is an autoimmune disease which affects multiple organs including the pancreas, bile duct, salivary glands and retroperitoneum. Further, it was recently reported that it can be manifested as periarteritis, often as inflammatory abdominal aortic aneurysm. We describe the case of a 75-year-old man with autoimmune pancreatitis and parotitis who presented with angina. The serum concentration of IgG4 was significantly increased at 2,510 mg/dl. Coronary angiography showed multiple stenotic lesions and pronounced dilatation of the right coronary artery. Cardiac computed tomography disclosed increased wall thickness of the coronary arteries and focal tumorous lesions surrounding the right coronary artery. Treatment with steroids proved only marginally effective and he underwent surgical resection of the aneurysm and coronary artery bypass grafting. The diagnosis of IgG4-related systemic disease was confirmed by histological examination of the resected mass, which showed a massive infiltration of IgG4-positive plasma cells. This case emphasizes the importance of considering the diagnosis in any patient with abnormally increased wall thickness or ectatic lesions in the coronary arteries.

Abnormal transforming growth factor-beta (TGF-beta) signaling is a critical contributor to the pathogenesis of various human diseases ranging from tissue fibrosis to tumor formation. Excessive TGF-beta signaling stimulates fibrotic responses. Recent research has focused in the main on the antiproliferative effects of TGF-beta in fibroblasts, and it is presently understood that TGF-beta-stimulated cyclooxygenase-2 (COX-2) induction in fibroblasts is essential for antifibroproliferative effects of TGF-beta. Both TGF-beta and COX-2 have been implicated in tumor growth, invasion, and metastasis, and therefore tumor-associated fibroblasts are a recent topic of interest. Here we report the identification of positive and negative regulatory factors of COX-2 expression induced by TGF-beta as determined using proteomic approaches. We show that TGF-beta coordinately up-regulates three factors, heterogeneous nuclear ribonucleoprotein A/B (HNRPAB), nucleotide diphosphate kinase A (NDPK A), and nucleotide diphosphate kinase A (NDPK B). Functional pathway analysis showed that HNRPAB augments mRNA and protein levels of COX-2 and subsequent prostaglandin E(2) (PGE(2)) production by suppressing degradation of COX-2 mRNA. In contrast, NDPK A and NDPK B attenuated mRNA and protein levels of COX-2 by affecting TGF-beta-Smad2/3/4 signaling at the receptor level. Collectively, we report on a new regulatory pathway of TGF-beta in controlling expression of COX-2 in fibroblasts, which advances our understanding of pathophysiological mechanisms of TGF-beta.

Krüppel-like factor 5 (KLF5), originally isolated as a regulator of phenotypic modulation of vascular smooth muscle cells, induces pathological cell growth and is expressed in the neointima. Although induction of KLF5 up-regulates growth factors like platelet-derived growth factor-A chain, how KLF5 actually contributes to vascular remodeling, notably its direct effects on cell proliferation, had been poorly clarified. To investigate the effects of KLF5 on neointimal formation, we at first performed adenoviral overexpression of KLF5 to rats subjected to carotid balloon injury. Neointimal formation and proliferating cell nuclear antigen-positive rate were significantly increased at 14 days after injury in the KLF5-treated animals. At the cellular level, overexpression of KLF5 also resulted in markedly increased cell proliferation and cell cycle progression. As a molecular mechanism, we showed that KLF5 directly bound to the promoter and up-regulated gene expression of cyclin D1, as well as showing specific transactivation of cyclins and cyclin-dependent kinase inhibitors in cardiovascular cells. Conversely, knockdown of KLF5 by RNA interference specifically down-regulated cyclin D1 and impaired vascular smooth muscle cell proliferation. Furthermore, KLF5 attenuated cleavage of caspase-3 under conditions of apoptotic stimulation. Moreover, KLF5-administered animals exhibited a significant decrease in terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling-positive cells in the medial layer, suggesting inhibition of apoptosis in the early phase after denudation. These findings collectively suggest that KLF5 plays a central role in cardiovascular pathologies through direct and specific stimulation of cell growth as well as inhibition of apoptosis.

We show that transcription factor Krüppel-like factor 5 (KLF5), which is important in cardiovascular remodeling, interacts with retinoic acid receptor-alpha (RARalpha) to regulate downstream gene expression. Here, we investigated whether acyclic retinoid (ACR) regulates KLF5 and inhibits vascular remodeling. Co-immunoprecipitation and pull-down binding assay showed that ACR attenuates functional interaction of KLF5 and RARalpha. ACR affects KLF5 functions by regulating transactivation of platelet-derived growth factor A (PDGF-A) chain. ACR may be a new vascular therapy to target KLF5 in cardiovascular pathology.

Regulation of chromatin in eukaryotic transcription requires histone-modifying enzymes, nucleosome remodeling complexes, and histone chaperones. Specific regulation of histone incorporation/eviction by histone chaperones on the promoter (e.g., region specific) is still poorly understood. In the present study, we show that direct and functional interaction of histone chaperone and DNA-binding transcription factor leads to promoter region-specific histone incorporation and inhibition of histone acetylation. We report here that the DNA-binding transcription factor Krüppel-like factor 5 (KLF5) interacts with the novel histone chaperone acidic nuclear phosphoprotein 32B (ANP32B), leading to transcriptional repression of a KLF5-downstream gene. We further show that recruitment of ANP32B onto the promoter region requires KLF5 and results in promoter region-specific histone incorporation and inhibition of histone acetylation by ANP32B. Extracellular stimulus (e.g., phorbol ester) regulates this mechanism in the cell. Collectively, we have identified a novel histone chaperone, ANP32B, and through analysis of the actions of this factor show a new mechanism of promoter region-specific transcriptional regulation at the chromatin level as mediated by the functional interaction between histone chaperone and DNA-binding transcription factor.

OBJECTIVES: Acyclic retinoid (ACR) is a synthetic retinoid with a high safety profile that has been pursued with high expectations for therapeutic use in prevention (recurrence) and treatment of malignancies. With the objective of addressing the therapeutic potential in the cardiovasculature, namely neointima formation, effects of ACR on neointima formation and the involved mechanisms were investigated. METHODS AND RESULTS: ACR was administered to cuff-injured mice which showed inhibition of neointima formation. Investigation of involved mechanisms at the cellular and molecular levels showed that ACR induces apoptosis of neointimal cells and this to be mediated by selective induction of retinoic-acid receptor beta (RARbeta) which shows growth inhibitory and proapoptotic effects on smooth muscle cells. CONCLUSION: We show that ACR inhibits neointima formation by inducing RARbeta which in turn inhibits cell growth and induces apoptosis. The retinoid, ACR, may be potentially exploitable for treatment and prevention of neointima formation.

Krüppel-like factor 5 (KLF5) is a transcription factor important in regulation of the cardiovascular response to external stress. KLF5 regulates pathological cell growth, and its acetylation is important for this effect. Its mechanisms of action, however, are still unclear. Analysis in KLF5-deficient mice showed that KLF5 confers apoptotic resistance in vascular lesions. Mechanistic analysis further showed that it specifically interacts with poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme important in DNA repair and apoptosis. KLF5 interacted with a proteolytic fragment of PARP-1, and acetylation of KLF5 under apoptotic conditions increased their affinity. Moreover, KLF5 wild-type (but not a non-acetylatable point mutant) inhibited apoptosis as induced by the PARP-1 fragment. Collectively, we have found that KLF5 regulates apoptosis and targets PARP-1, and further, for acetylation to regulate these effects. Our findings thus implicate functional interaction between the transcription factor KLF5 and PARP-1 in cardiovascular apoptosis.

Protein profiling would aid in better understanding the pathophysiology of metabolic disease. Here, we report on differential proteomic analysis using an animal model of diabetes mellitus and associated metabolic disorders (Otsuka Long-Evans Tokushima Fatty rat). Serum was analyzed by a new two-dimensional liquid chromatography system which separated proteins by chromatofocusing and subsequent reversed-phase chromatography. This is the first application of this approach to differential serum proteomics. Differentially expressed proteins, identified with MALDI-TOF mass spectrometry, included apolipoproteins and alpha2-HS-glycoprotein. These findings add to our understanding of the underlying pathophysiology. This new proteomic analysis is a promising tool to elucidate disease mechanisms.

Although cholesterol embolism syndrome was recognized as a clinicopathologic entity more than 50 years ago, it is attracting growing attention recently. It is a multisystemic disorder in which cholesterol crystals released from atherosclerotic plaques obstruct small arterioles, resulting in local ischemia and end-organ damage. There are no established treatments, and with the limited treatment options available, it is important to make the diagnosis as early as possible. We present the case of a 68-year-old man with cholesterol embolism who had a few fluttering atheromas in the aorta, as demonstrated by transesophageal ultrasonography. The diagnosis was confirmed by skin biopsy, and treatment with statins and steroids proved effective, as renal failure progressively improved. This case emphasizes the importance of early diagnosis and shows the possible therapeutic effects of statins and steroids for patients with this syndrome.

BACKGROUND: Functional mitral regurgitation (MR) is one of the common and severe complications in patients with dilated cardiomyopathy. The detailed mechanisms that cause functional MR remain to be elucidated. Using two-dimensional transthoracic echocardiography, we investigated the differences in major determinants of MR severity between ischemic cardiomyopathy (ICM) and non-ICM patients. METHODS: We enrolled 103 patients (91 males; age 64+/-12 years) with significant left ventricular (LV) dilatation. They were divided into ICM group (n=69) with significant coronary disease, and non-ICM (n=34) group without coronary disease. We devised a novel and simple parameter; the short-axis sphericity index (SI), to evaluate global LV remodeling, and used coaptation depth (CD) and tenting area (TA) to evaluate mitral deformity. RESULTS: In all cases, CD, TA and left atrium diameter (LAD) correlated positively with maximum regurgitation area (MRA) (r=0.54, 0.57, 0.57; P<0.0001). A negative correlation was observed between MRA and SI (r=-0.33, P=0.0008). There was no significant relationship between MRA and LV ejection fraction (EF). In non-ICM cases, SI tended to be lower with reduced EF. Multivariate stepwise linear regression analysis showed the following equations; ICM: MRA=-9.4+0.81CD+0.21LAD (r2=0.47, P<0.0001), non-ICM: MRA=-7.2+0.17LVDs (LV end systolic diameter) -8.7SI+0.27LAD (r2=0.63, P<0.0001). CONCLUSIONS: The strongest determinants of functional MR severity differ in ICM and non-ICM. While LV diameter and SI (global LV remodeling index) mainly determine the severity in non-ICM, CD that reflects mitral deformity is the major determinant in ICM.

AIMS: To examine the impact of pre-operative atrial fibrillation (AF) on the outcome of mitral valve repair (MVR) for degenerative mitral regurgitation (MR). METHODS AND RESULTS: Among 392 patients with moderate to severe MR who underwent MVR between 1991 and 2002, 283 patients with isolated degenerative MR were followed for 4.7+/-3.3 years. Of 27 deaths, nine were due to cardioembolic events and four were due to left ventricular (LV) dysfunction. When compared with patients with pre-operative AF, those with sinus rhythm (SR) had better survival (96+/-2.1 vs. 87+/-3.2% at 5 years, P=0.002) and higher cardiac event-free rates (96+/-2.0 vs. 75+/-4.4% at 5 years, P<0.001). In patients with pre-operative SR, observed and expected survival were similar (P=0.811). Cox multivariable regression analysis confirmed AF [P=0.027, adjusted hazard ratio (AHR) 2.9] and age as independently predictive of survival, and AF (P=0.002, AHR 3.1), New York Heart Association Class, and LV fractional shortening as independently predictive of cardiac event. CONCLUSION: Death due to LV dysfunction was not frequent and cardioembolic events due to AF were the leading cause for cardiac death. Pre-operative AF became a strong independent predictor of survival and morbidity. Patients with pre-operative SR had excellent prognosis. The benefits of preventing cardioembolic events due to AF validate the indication of MVR for patients with high risk for AF.

The Krüppel-like factor (KLF) family is a recently highlighted group of zinc finger transcription factors given their important biological roles which include the vasculature. KLF2, KLF4, KLF5, and KLF6 are notable factors that have been implicated in developmental as well as pathological vascular processes. In this brief review, we provide an up-to-date summary of the physiological functions and cellular effects as well as transcriptional regulatory mechanisms of the vascular KLFs. Through such, we aim to provide a working view for understanding the pathological actions of KLFs in the vasculature.

Transcriptional regulation in eukaryotes requires an understanding of the regulation of the chromatin structure. Chromatin is the eukaryotic-specific packaging/compaction of DNA with nucleosomal histones. This present review discusses recent advancements made in the field of chromatin-associated transcriptional regulation and their implications to the cardiovasculature.

Transcription is regulated by a network of transcription factors and related cofactors that act in concert with the general transcription machinery. Elucidating their underlying interactions is important for understanding the mechanisms regulating transcription. Recently, we have shown that Krüppel-like factor KLF5, a member of the Sp/KLF family of zinc finger factors and a key regulator of cardiovascular remodeling, is regulated positively by the acetylase p300 and negatively by the oncogenic regulator SET through coupled interaction and regulation of acetylation. Here, we have shown that the deacetylase HDAC1 can negatively regulate KLF5 through direct interaction. KLF5 interacts with HDAC1 in the cell and in vitro. Gel shift DNA binding assay showed that their interaction inhibits the DNA binding activity of KLF5, suggesting a property of HDAC1 to directly affect the DNA binding affinity of a transcription factor. Reporter assay also revealed that HDAC1 suppresses KLF5-dependent promoter activation. Additionally, overexpression of HDAC1 suppressed KLF5-dependent activation of its endogenous downstream gene, platelet-derived growth factor-A chain gene, when activated by phorbol ester. Further, HDAC1 binds to the first zinc finger of KLF5, which is the same region where p300 interacts with KLF5 and, intriguingly, HDAC1 inhibits binding of p300 to KLF5. Direct competitive interaction between acetylase and deacetylase has been hitherto unknown. Collectively, the transcription factor KLF5 is negatively regulated by the deacetylase HDAC1 through direct effects on its activities (DNA binding activity, promoter activation) and further through inhibition of interaction with p300. These findings suggest a novel role and mechanism for regulation of transcription by deacetylase.

The transcription factor Krüppel-like factor 5 (KLF5) and its genetically downstream target gene platelet-derived growth factor-A (PDGF-A) chain are key factors in regulation of cardiovascular remodeling in response to stress. We show that KLF5 mediates a novel distinct delayed persistent induction of PDGF-A chain in response to the model agonist, phorbol ester, through a cis-element previously shown to mediate phorbol ester induction on to PDGF-A chain through the early growth response factor (Egr-1). Interestingly, the nuclear factor-kappaB (NF-kappaB) p50 subunit further cooperatively activates PDGF-A chain through protein-protein interaction with KLF5 but not Egr-1. RNA interference analysis confirmed that KLF5 and p50 are important for induction of PDGF-A chain. Collectively, we identify a novel regulatory pathway in which PDGF-A chain gene expression, under the control of KLF5, is cooperatively activated by the NF-kappaB p50 subunit and a pathophysiological stimulus.

The optimal timing of surgical correction of severe mitral regurgitation (MR) is important for improved morbidity and mortality. We utilized a scoring system to decide the timing of procedures. Based on clinical features and echocardiographic data, we hypothesized that preoperative semi-quantitation of MR using this scoring system may be useful for predicting prognosis after repair. The MR score was composed of 6 parameters associated with disease severity (i.e., history of heart failure, atrial fibrillation, pulmonary hypertension, left ventricular end-systolic dimension, fractional shortening, and left atrial dimension). The maximum score was 6. Of 267 patients who underwent mitral valve repair in the last 10 years, 191 patients with mitral valve prolapse were studied. Patients were categorized into 2 groups according to MR score (group low [L] : 0 to 2.5 and group high [H]: >/=3.0) irrespective of New York Heart Association functional class. A significant difference in postoperative event-free survival was observed between both groups (p = 0.0014); the adjusted risk ratio was 3.4 (95% confidence interval 1.6 to 7.2). Postoperative echocardiography showed larger left ventricular systolic dimensions (p <0.0001), lower fractional shortening (p = 0.0016), and larger left atrial dimensions (p <0.0001) in group H than group L. Thus, an MR score is a simple way to predict the prognosis of severe MR independently of subjective symptoms in patients undergoing mitral valve repair.

OBJECTIVES: This study sought to determine whether echocardiography before mitral valve repair (MVR) for mitral regurgitation (MR) was predictive of postoperative left ventricular (LV) dysfunction and useful for deciding the optimal timing of repair. BACKGROUND: Some reports have shown that the preoperative echocardiographic data of left ventricular ejection fraction (LVEF) and left ventricular end-systolic diameter (LVDs) were good predictors of postoperative LV dysfunction. However, few reports were based on long-term follow-up data of large numbers of patients who underwent MVR in the last decade. METHODS: A total of 274 patients with moderate or severe MR underwent MVR between October 1, 1991, and September 30, 2000. Among them, 171 patients who had both an operation for isolated MR due to degenerative pathology and a postoperative echocardiogram were studied. Postoperative echocardiograms were performed 3.9 +/- 2.4 years after the operation. The LVEF decreased from 66 +/- 10% before surgery to 63 +/- 11% after surgery (p < 0.0001). On univariate analysis, preoperative LVEF and LVDs correlated with postoperative LVEF (r = 0.41 and r = -0.39, respectively). Overall, postoperative LV dysfunction (defined as LVEF <50%) was not frequent (12%). However, the incidence of postoperative LV dysfunction was high in patients with preoperative LVEF <55% (38%) or LVDs > or =40 mm (23%). CONCLUSIONS: In patients with MR, the echocardiographic data of LVEF and LVDs were good predictors of postoperative LV dysfunction. When a decrease in LVEF or an increase in LVDs is detected, MVR should be considered to preserve postoperative LV function.

BACKGROUND: Recent studies on the etiology of aortic valve disease in the US showed a decrease in rheumatic valve disease and an increase in age-related degenerative disease. The purpose of this study was to describe the etiology of aortic valve disease and its temporal changes in Japan, based on a large number of cases. METHODS: The medical charts of all patients who underwent aortic valve replacement at our institute between 1977 and 1999 were reviewed. Among the 600 patients analyzed, 213 (36%) had pure aortic stenosis, 265 (44%) had pure aortic regurgitation, and 122 (20%) had combined stenosis and regurgitation. RESULTS: The causes were rheumatic change (49%), degenerative change (19%), bicuspid valves (18%), infective endocarditis (5%) and others (9%). Rheumatic disease continued to be the most common cause of aortic stenosis, but its frequency decreased from 100% in 1977-1979 to 37% in 1995-1999. In contrast, the frequency of degenerative change among stenotic valves increased recently from 11% in 1990-1994 to 30% in 1995-1999. Similarly, rheumatic disease remained to be the leading cause of aortic regurgitation, with a decline in frequency from 46% in 1985-1989 to 27% in 1995-1999. The percentage of degenerative change among regurgitant valves did not change appreciably. CONCLUSIONS: There was a shift in the causes of aortic valve disease, with a decrease in rheumatic disease and an increase in degenerative disease. This trend was similar to that observed in the US. These findings suggest the increasing importance of aortic valve disease due to degenerative change.

OBJECTIVES: Whether beta-blocker therapy changes the circulating levels of cytokines as congestive heart failure improves remains uncertain. METHODS: Nine patients with idiopathic dilated cardiomyopathy, who had previously received conventional treatment and were classified as New York Heart Association (NYHA) functional class II, received carvedilol by stepwise dose increase up to 20 mg daily, and the plasma interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) levels were measured. RESULTS: IL-6 was significantly reduced from 0.80 +/- 0.49 pg/ml before therapy to 0.21 +/- 0.08 pg/ml after carvedilol was increased to 20 mg daily (p < 0.05). Moreover, IL-6 level had already decreased significantly compared to the baseline when the dose of carvedilol had reached 10 mg daily (0.28 +/- 0.12 pg/ml, p < 0.05). TNF-alpha levels did not change significantly. CONCLUSIONS: These results demonstrate that IL-6 concentration is significantly decreased by beta-blocker therapy. The efficacy for heart failure may be related to the change of IL-6 concentration.