Kumi Yasukawa

A genome-wide association study identifies three new risk loci for Kawasaki disease

We performed a genome-wide association study (GWAS) of Kawasaki disease in Japanese subjects using data from 428 individuals with Kawasaki disease (cases) and 3,379 controls genotyped at 473,803 SNPs. We validated the association results in two independent replication panels totaling 754 cases and 947 controls. We observed significant associations in the FAM167A-BLK region at 8p22-23 (rs2254546, P = 8.2 × 10−21), in the human leukocyte antigen (HLA) region at 6p21.3 (rs2857151, P = 4.6 × 10−11) and in the CD40 region at 20q13 (rs4813003, P = 4.8 × 10−8). We also replicated the association of a functional SNP of FCGR2A (rs1801274, P = 1.6 × 10−6) identified in a recently reported GWAS of Kawasaki disease. Our findings provide new insights into the pathogenesis and pathophysiology of Kawasaki disease.

Prognostic Impact of Vascular Leakage in Acute Kawasaki Disease

Background Increased microvascular permeability is an initial step of Kawasaki disease (KD). We reported that vascular endothelial growth factor (VEGF) might play a role in the vascular leakage of KD. In fatal KD, plasma leakage was extensively documented at VEGF‐positive microvessels. Increases in vascular leakage cause hypoalbuminemia and noncardiogenic edema. However, the prognostic impact of vascular leakage in KD remains unclear. Methods and Results We compared 76 patients who became afebrile within 5 days after starting intravenous gamma globulin (IVGG) (2 g/kg over 5 days) (IVGG‐responsive) with 27 patients who did not respond (IVGG‐resistant). Baseline levels of serum VEGF and albumin were similar between the groups. After IVGG, VEGF levels increased (P<0.0001) and albumin levels decreased (P<0.00001) in both groups. However, the IVGG‐resistant group had higher VEGF levels (P=0.029) and severe hypoalbuminemia (P<0.00001) compared with the IVGG‐responsive group. Coronary aneurysms were documented in 12 patients from the IVGG‐resistant group but not in the IVGG‐responsive group. Then IVGG‐resistant patients were divided into 2 subgroups according to the presence (n=12) or absence (n=15) of coronary aneurysms. There was no difference between subgroups in age, sex, laboratory data including albumin, and retreated doses of IVGG. However, body weight gain after IVGG was documented in patients who subsequently developed coronary aneurysms (P=0.003) but not in those who did not (P=0.967). Conclusions These results suggest that vascular leakage may be a key feature of KD pathophysiology. The present study may provide better insights into the pathogenesis and treatment of patients resistant to IVGG in acute KD. (Circulation. 2003;108:325‐330.)

Isolated noncompaction of ventricular myocardium associated with fatal ventricular fibrillation.

A female infant with isolated noncompaction of ventricular myocardium who developed ventricular tachyarrhythmia is described. Wolff-Parkinson-White syndrome was shown by electrocardiography. At 9 months of age, the patient suddenly developed cardiac arrest. Electrocardiography following resuscitation with DC cardioversion demonstrated sinus rhythm without delta wave. The QT interval was normal. Frequent premature ventricular captures caused ventricular fibrillation. DC cardioversion was necessary to terminate frequent attacks of ventricular fibrillation until the introduction of beta blockers and lidocaine. Two-dimensional echocardiogram confirmed the diagnosis of isolated non-compaction of ventricular myocardium. Three months later, the patient died of ventricular fibrillation during respiratory syncytial viral infection.

Dramatic decrease of circulating levels of monocyte chemoattractant protein-1 in Kawasaki disease after gamma globulin treatment.

Kawasaki disease (KD) is a systemic vasculitis preferentially affecting coronary arteries. Extensive monocytes/macrophages infiltrate in the vascular lesions, implying the involvement of a chemotactic cytokine in their recruitment. We investigated the role of monocyte chemoattractant protein‐1 (MCP‐1, also termed monocyte chemotactic and activating factor) in KD. In the immunohistochemical studies using the cardiac tissues of patients with fatal KD, MCP‐1 but not interleukin (IL) ‐8 or macrophage inflammatory protein‐1α was localized at the extracellular matrix associated with mononuclear cellular infiltration. The sites of MCP‐1 expression correlated with the distribution of the acute inflammation, including early coronary vasculitis. In prospectively studied patients with KD, circulating levels of MCP‐1, IL‐8, tumor necrosis factor a (TNF‐α), and IL‐1α were elevated in 73, 77, 57, and 0% of samples before gamma globulin (GG) treatment (400 mg/kg × 5 days = total 2 g/kg), respectively, compared with respective control values. GG treatment correlated with a rapid decrease in the circulating levels of MCP‐1 (P = 0.001) but not IL‐8 (P = 0.19) or TNF‐α (P = 0.33). In the sensitive Western blotting, MCP‐1 bound to GG. Furthermore, GG inhibited the MCP‐1‐induced Ca2+ influx in a human monocytic cell line in vitro. These findings suggest a role of MCP‐1 in KD, and indicate that GG treatment may block MCP‐1 activity, thus alleviating KD vasculitis. J. Leukoc. Biol. 65: 566–572; 1999.

ITPKC and CASP3 polymorphisms and risks for IVIG unresponsiveness and coronary artery lesion formation in Kawasaki disease

Functional single-nucleotide polymorphisms (SNPs) in inositol 1,4,5-trisphosphate 3-kinase C (ITPKC) (rs28493229) and caspase-3 (CASP3) (rs113420705; formerly rs72689236) are associated with susceptibility to Kawasakis disease (KD). To evaluate the involvement of these 2 SNPs in the risk for intravenous immunoglobulin (IVIG) unresponsiveness, we investigated 204 Japanese KD patients who received a single IVIG dose of 2 g kg−1 (n=70) or 1 g kg−1 daily for 2 days (n=134). The susceptibility allele of both SNPs showed a trend of overrepresentation in IVIG non-responders and, in combined analysis of these SNPs, patients with at least 1 susceptible allele at both loci had a higher risk for IVIG unresponsiveness (P=0.0014). In 335 prospectively collected KD patients who were treated with IVIG (2 g kg−1), this 2-locus model showed a more significant association with resistance to initial and additional IVIG (P=0.011) compared with individual SNPs. We observed a significant association when all KD patients with coronary artery lesions were analyzed with the 2-locus model (P=0.0031). Our findings strongly suggest the existence of genetic factors affecting patients’ responses to treatment and the risk for cardiac complications, and provide clues toward understanding the pathophysiology of KD inflammation.

Elevated granulocyte colony-stimulating factor levels predict treatment failure in patients with Kawasaki disease

BACKGROUND Kawasaki disease (KD) is an acute vasculitis in young children, frequently associated with coronary artery aneurysms. The intravenous infusion of high-dose IgG (IVIG) effectively reduces the systemic inflammation and the incidence of coronary artery lesions, although the precise underlying mechanisms are unknown. OBJECTIVE We performed expression profiling of whole blood cells to investigate the mechanisms underlying the effect of IVIG and to identify biomarkers associated with unresponsiveness to IVIG. METHODS We compared the transcript abundance among pre-IVIG and post-IVIG patients and febrile control patients. Then we analyzed the mRNA levels and the protein levels among the different cohort of patients with KD who were either responsive or nonresponsive to the initial IVIG. RESULTS A total of 298 transcripts were overrepresented or underrepresented in the pre-IVIG patients compared with post-IVIG patients and febrile controls, of which 15 transcripts were differentially expressed in nonresponsive patients with KD compared with responsive patients before IVIG. The protein levels of polycythemia rubra vera 1, which was one of the most variably expressed transcripts in pre-IVIG patients, and the serum granulocyte colony-stimulating factor levels were significantly higher in nonresponsive patients than in responsive patients before the initial IVIG administration. CONCLUSION These findings suggest that the variable gene expression profiles were correlated to the responses of patients with KD to IVIG administration. Polycythemia rubra vera 1 and granulocyte colony-stimulating factor levels may be good biomarkers for predicting response to IVIG in patients with KD.

Alleviation of Myocardial Ischemia After Kawasaki Disease by Heparin and Exercise Therapy

Background—Heparin promotes angiogenesis. We evaluated the effects of combined treatment with heparin and exercise on myocardial ischemia in the chronic stage of Kawasaki disease. Methods and Results—This study was conducted in 7 patients (aged 6 to 19 years) who had a totally occluded coronary artery and stress-induced myocardial ischemia in the collateral-dependent areas. Twice-daily exercise using a bicycle ergometer was performed with increments of 0.5 W/kg every 3 minutes up to maximal exertion for 10 days. Heparin, which immediately increased circulating hepatocyte growth factor, was given intravenously 10 minutes before each exercise period. Newly developed myocardial infarction, ventricular tachyarrhythmia, anginal attack, or hemorrhagic complication was not observed in any patient. Dipyridamole-loading single photon emission computed tomography documented improved myocardial perfusion in the collateral-dependent areas and a significant reduction in total defect scores in all patients after the completion of 20 sessions (P =0.01). In control patients who did not receive the heparin-exercise therapy, however, stress defect scores remained unchanged (n=1) or increased (n=2) during follow-up. Computerized quantitative coronary angiography provided evidence that the heparin-exercise therapy increased the diameter of the occluded artery to which collaterals terminated (P =0.001) but not that of the reference artery with which collaterals were not connected (P =0.96). Conclusions—The findings suggest that a series of heparin and exercise treatments over 10 days may have a dramatic effect on the alleviation of myocardial ischemia in collateral-dependent regions. This may be a safe, noninvasive revascularization therapy for patients with coronary artery occlusion in the chronic stage of Kawasaki disease.

Zebrafish Gene Knockdowns Imply Roles for Human YWHAG in Infantile Spasms and Cardiomegaly

Williams‐Beuren syndrome (WBS) is a neurodevelopmental disorder presenting with an elfin‐like face, supravalvular aortic stenosis, a specific cognitive‐behavioral profile, and infantile hypercalcemia. We encountered two WBS patients presenting with infantile spasms, which is extremely rare in WBS. Array comparative genomic hybridization (aCGH) and fluorescent in situ hybridization (FISH) analyses revealed atypical 5.7‐Mb and 4.1‐Mb deletions at 7q11.23 in the two patients, including the WBS critical region and expanding into the proximal side and the telomeric side, respectively. On the proximal side, AUTS2 and CALN1 may contribute to the phenotype. On the telomeric side, there are two candidate genes HIP1 and YWHAG. Because detailed information of them was unavailable, we investigated their functions using gene knockdowns of zebrafish. When zebrafish ywhag1 was knocked down, reduced brain size and increased diameter of the heart tube were observed, indicating that the infantile spasms and cardiomegaly seen in the patient with the telomeric deletion may be derived from haploinsufficiency of YWHAG. genesis 48:233–243, 2010.

Variations in ORAI1 Gene Associated with Kawasaki Disease

Kawasaki disease (KD; MIM#61175) is a systemic vasculitis syndrome with unknown etiology which predominantly affects infants and children. Recent findings of susceptibility genes for KD suggest possible involvement of the Ca(2+)/NFAT pathway in the pathogenesis of KD. ORAI1 is a Ca(2+) release activated Ca(2+) (CRAC) channel mediating store-operated Ca(2+) entry (SOCE) on the plasma membrane. The gene for ORAI1 is located in chromosome 12q24 where a positive linkage signal was observed in our previous affected sib-pair study of KD. A common non-synonymous single nucleotide polymorphism located within exon 2 of ORAI1 (rs3741596) was significantly associated with KD (P = 0.028 in the discovery sample set (729 KD cases and 1,315 controls), P = 0.0056 in the replication sample set (1,813 KD cases vs. 1,097 controls) and P = 0.00041 in a meta-analysis by the Mantel-Haenszel method). Interestingly, frequency of the risk allele of rs3741596 is more than 20 times higher in Japanese compared to Europeans. We also found a rare 6 base-pair in-frame insertion variant associated with KD (rs141919534; 2,544 KD cases vs. 2,414 controls, P = 0.012). These data indicate that ORAI1 gene variations are associated with KD and may suggest the potential importance of the Ca(2+)/NFAT pathway in the pathogenesis of this disorder.

Clinically mild infantile encephalopathy associated with excitotoxicity

Acute infectious encephalopathy is very frequently observed in children in East Asia including Japan. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is the most common subtype in Japan; however, more than 40% of the patients remain unclassified into specific syndromes. To investigate the underlying pathomechanism in those with unclassified acute encephalopathy, we evaluated brain metabolism by MR spectroscopy. Among 20 patients with acute encephalopathy admitted to our hospital during January 2015 to May 2016, 12 could not be classified into specific syndromes. MR spectroscopy was performed in 8 of these 12 patients with unclassified encephalopathy. MR spectroscopy showed an increase of glutamine with a normal N-acetyl aspartate level on days 3 to 8 in three of the 8 patients, which had normalized by follow-up studies. The three patients clinically recovered completely. This study suggests that excitotoxicity may be the underlying pathomechanism in some patients with unclassified mild encephalopathy.