Non-receptor type, proline-rich protein tyrosine kinase 2 (Pyk2) is a possible therapeutic target for Kawasaki disease.

Kawasaki disease (KD) is a paediatric vasculitis whose pathogenesis remains unclear. Based on experimental studies using a mouse model for KD, we report here that proline-rich protein tyrosine kinase 2 (Pyk2) plays a critical role in the onset of KD-like murine vasculitis. The mouse model for KD was prepared by administrating a Candida albicans water-soluble fraction (CAWS). Unlike CAWS-treated WT mice, CAWS-treated Pyk2-Knockout (Pyk2-KO) mice did not develop apparent vasculitis. A sustained increase in MIG/CXCL9 and IP-10/CXCL10, both of which have potent angiostatic activity, was observed in CAWS-treated Pyk2-KO mice. CAWS-induced activation of STAT3, which negatively regulates the expression of these chemokines, was also attenuated in macrophages derived from Pyk2-KO mice. The present study suggests that defects in Pyk2 suppress KD-like experimental vasculitis, presumably through CXCL9- and CXCL10-dependent interference with neo-angiogenesis. Since Pyk2-KO mice show no life-threatening phenotype, Pyk2 may be a promising therapeutic molecular target for KD.

Oxidative stress and Kawasaki disease: how is oxidative stress involved from the acute stage to the chronic stage?

Inflammation and oxidative stress are closely related. Further, oxidative stress plays an important role in the pathology of inflammation-based Kawasaki disease. An excessive in vivo production of reactive oxygen species increases oxidative stress in the body, which triggers an endless vicious spiral of inflammation reactions and reactive oxygen metabolites. This presumably forms diffuse vasculitis in the acute phase. Acute inflammation and oxidative stress can be rapidly controlled by treatments; however, they may remain for a long time. This has recently been identified as a problem in the chronic phase of Kawasaki disease. Generally, the presence of vascular inflammation and oxidative stress impairs blood vessels, leading to the onset of atherosclerosis, which is a widely recognized risk. The current discussion focuses on whether the same is valid for blood vessels in the chronic phase of Kawasaki disease.

The Application of a Modified d-ROMs Test for Measurement of Oxidative Stress and Oxidized High-Density Lipoprotein.

Reactive oxygen species (ROS) are involved in the initiation and progression of atherosclerosis. ROS-derived hydroperoxides, as an indicator of ROS production, have been measured by using the diacron reactive oxygen metabolites (d-ROMs) test, which requires iron-containing transferrin in the reaction mixture. In this study we developed a modified d-ROMs test, termed the Fe-ROMs test, where iron ions were exogenously added to the reaction mixture. This modification is expected to exclude the assay variation that comes from different blood iron levels in individuals. In addition, this Fe-ROMs test was helpful for determining the class of plasma lipoproteins that are hydroperoxidized. Low-density lipoprotein/very low-density lipoprotein (LDL/VLDL) and high-density lipoprotein (HDL) were purified by use of an LDL/VLDL purification kit and the dextran sulfate-Mg2+ precipitation method, respectively; their hydroperoxide contents were assessed by performing the Fe-ROMs test. The majority of the hydroperoxides were detected only in the HDL fraction, not in the LDL/VLDL. Further detailed analysis of HDLs by size-exclusion high-performance liquid chromatography revealed that the hydroperoxide-containing molecules were small-sized HDLs. Because HDL was shown to be the principal vehicle for the plasma hydroperoxides, this Fe-ROMs test is a beneficial method for the assessment of oxidized-HDL levels. Indeed, Fe-ROMs levels were strongly associated with the levels of oxidized HDL, which were determined by performing the malondialdehyde-modified HDL enzyme immunoassay. In conclusion, the Fe-ROMs test using plasma itself or the HDL fraction after dextran sulfate-Mg2+ precipitation is useful to assess the functionality of HDL, because the oxidation of HDL impairs its antiatherogenic capacity.

Transcriptional Analysis of Intravenous Immunoglobulin Resistance in Kawasaki Disease Using an Induced Pluripotent Stem Cell Disease Model.

BACKGROUND: Approximately 10-20% of Kawasaki disease (KD) patients are resistant to intravenous immunoglobulin (IVIG) treatment. Further, these patients are at a particularly high risk of having coronary artery abnormalities. The mechanisms of IVIG resistance in KD have been analyzed using patient leukocytes, but not patient vascular endothelial cells (ECs). The present study clarifies the mechanisms of IVIG resistance in KD using an induced pluripotent stem cell (iPSC) disease model.Methods and Results:Dermal fibroblasts or peripheral blood mononuclear cells from 2 IVIG-resistant and 2 IVIG-responsive KD patients were reprogrammed by the episomal vector-mediated transduction of 6 reprogramming factors. KD patient-derived iPSCs were differentiated into ECs (iPSC-ECs). The gene expression profiles of iPSC-ECs generated from IVIG-resistant and IVIG-responsive KD patients were compared by RNA-sequencing analyses. We found that the expression ofCXCL12was significantly upregulated in iPSC-ECs from IVIG-resistant KD patients. Additionally, Gene Set Enrichment Analysis (GSEA) revealed that gene sets involved in interleukin (IL)-6 signaling were also upregulated. CONCLUSIONS: The first iPSC-based model for KD is reported here. Our mechanistic analyses suggest thatCXCL12, which plays a role in leukocyte transmigration, is a key molecule candidate for IVIG resistance and KD severity. They also indicate that an upregulation of IL-6-related genes may be involved in this pathogenesis.

Platelet activation dynamics evaluated using platelet-derived microparticles in Kawasaki disease.

BACKGROUND: Little is known about the platelet dynamics and the effect of antiplatelet therapy in Kawasaki disease (KD). The aim of this study was to clarify platelet activation dynamics in acute-phase KD patients by assaying platelet-derived microparticles (PDMPs). METHODS AND RESULTS: The PDMP level in 18 patients with acute KD was measured on ELISA. Of the 18 patients, 14 were receiving oral aspirin and i.v. immunoglobulin (IVIG) and 4, oral aspirin alone. Blood samples were drawn before, immediately after, and 10-14 days after IVIG infusion; thereafter, at 1, 2, and 3 months after the onset of disease. PDMP level before aspirin treatment was significantly higher in acute-phase KD patients than in the control subjects with common febrile diseases (P<0.01). In the acute-phase KD patients, IVIG significantly decreased PDMP level; the PDMP level was not lower on the similar day of KD in the patients who did not receive IVIG. Eight patients' PDMP level rebounded after aspirin was discontinued. CONCLUSIONS: Platelets are activated during acute-phase KD, which confirms the importance of antiplatelet therapy. In addition, platelet activation continues as long as 2 or 3 months after the acute phase, the time at which aspirin is commonly discontinued, and the timing of aspirin discontinuation should therefore be evaluated in each individual patient.

Utility of whole-blood aggregometry for evaluating anti-platelet therapy for Kawasaki disease.

BACKGROUND: Anti-platelet therapy for Kawasaki disease (KD) is often done without monitoring drug efficacy. The aim of this study was to investigate the utility of whole-blood aggregometry to evaluate the efficacy of anti-platelet therapy for KD. METHODS: Of 37 late-phase KD patients included in the present study, 20 were prescribed anti-platelet drugs. Platelet-rich plasma (PRP) aggregation with collagen as the stimulus was measured using an optical aggregometer. The area under the curve of small and large size aggregations was calculated, and categorized into five classes: -2, -1, 0, 1, and 2. Whole-blood aggregation with collagen or adenosine 5'-diphosphate (ADP) as stimulus was evaluated using the platelet aggregation threshold index (PATI), which is the concentration of stimulus that induces a whole-blood aggregation rate of 50%. RESULTS: In both collagen- and ADP-induced aggregation, there was a negative correlation between PATI and class determination using the PRP technique (collagen, rs = -0.870, P < 0.0001; ADP, rs = -0.620, P < 0.0001). Moreover, the PATI in collagen- and ADP-induced aggregation was significantly higher in the anti-platelet drug therapy group than in the untreated group (collagen, P < 0.0001; ADP, P = 0.0002). The serum thromboxane B2 level in the anti-platelet drug therapy group was also significantly lower than that in the untreated group (P < 0.0001). PATI was significantly higher in those treated with thienopyridine drug combinations than those without drug therapy (P = 0.0036). CONCLUSIONS: Whole-blood aggregometry is useful for monitoring the efficacy of anti-platelet therapy for KD.

Dynamics of reactive oxygen metabolites and biological antioxidant potential in the acute stage of Kawasaki disease.

BACKGROUND: The dynamics of oxidation/reduction control system activities using reactive oxygen metabolites (ROM) and biological antioxidant potential (BAP) in acute stage patients was evaulated to understand the mechanism of vascular injury and remodeling in Kawasaki disease (KD). METHODS AND RESULTS: ROM, BAP, high-sensitivity C-reactive protein (hs-CRP), interleukin-1,2,6, and tumour necrosis factor-α in 19 KD patients were measured. ROM decreased in good correlation only with hs-CRP (P<0.05) at 2 weeks after intravenous immunoglobulin (IVIG). Patients were further classified as responding well (Group A) or responding poorly (Group B) to IVIG. Both treatment groups had significantly higher ROM values than the control group (P<0.01). ROM decreased in Group A both immediately and 2 weeks after the IVIG treatment (P<0.05), but it did not decrease in Group B until 2 weeks post-treatment (P<0.01). BAP levels were unremarkable in Group A, but were significantly lower in Group B than in both other groups (P<0.05). BAP increased in Group A 2 weeks after IVIG treatment (P<0.01), but remained low in Group B (P<0.01). CONCLUSIONS: Acute stage KD patients suffer from obvious hyperoxidant stress, and improved in response to IVIG treatment in most patients. Blood BAP level might be a useful index for predicting responsiveness to IVIG the treatment.

Matrix metalloproteinase-9 in vascular lesions and endothelial regulation in Kawasaki disease.

BACKGROUND: Matrix metalloproteinases (MMPs) contribute to extracellular remodeling in Kawasaki disease (KD). MMP-9 is an essential vasculature-remodeling factor but its role in the vascular lesions of KD is not understood. This study focused on MMP-9 regulation via cytokines in endothelial cells (ECs). METHODS AND RESULTS: Plasma and peripheral blood mononuclear cells were obtained from 30 KD patients, and 15 non-febrile and 25 febrile children. Plasma MMP-1, -2, -9, and tissue inhibitor of MMP (TIMP)-1 and -2 were measured by 2-step sandwich ELISA. Immunohistology was performed on coronary arterial lesions (CAL) from a patient who died of KD in the acute phase. MMP-9 mRNA expression in human umbilical ECs (HUVECs) treated with plasma or cytokines, and in mononuclear cells was measured by semi-quantitative reverse transcription-polymerase chain reaction. Plasma MMP-1, -2 and TIMP-2 levels were normal for KD. Plasma MMP-9 and TIMP-1 levels increased during the acute phase of the disease (P<0.001 vs each control). MMP-9 stained diffusely in CAL. MMP-9 mRNA levels were higher in HUVECs treated with plasma in the acute and convalescent phases. Interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha stimulated MMP-9 expression, whereas interferon (IFN)-gamma suppressed it. There was no MMP-9 mRNA elevation in mononuclear cells. CONCLUSIONS: ECs are a source of MMP-9 in the vascular lesions of KD. MMP-9 is regulated by cytokines IL-1beta, IL-6, TNF-alpha and IFN-gamma.

The involvement of the vasa vasorum in the development of vasculitis in animal model of Kawasaki disease.

BACKGROUND: Kawasaki Disease (KD) involves a diffuse and systemic vasculitis of unknown etiology that mainly affects infants and children. Although a considerable number of analyses of the clinical, histopathological and molecular biological details underlying the mechanism responsible for the development of coronary arterial lesions, it is still poorly understood.The purpose of this study was to analyze the state of angiogenesis, vasculogenesis and the distribution of blood vessels using an animal model of KD like vasculitis. We investigated the involvement of the vasa vasorum from the adventitia in the vascular involvement and the development of the disease state by performing sequential histopathology, scanning electron microscopy (SEM) and micro computed tomography (CT) studies using a murine model of vasculitis induced by the Candida albicans water-soluble fraction (CAWS). METHODS: To prepare the animal model of KD like vasculitis, CAWS was intraperitoneally injected into C57BL/6N mice for five consecutive days as reported by Ohno et al. We observed the changes of the vasa vasorum at the aorta and the orifices of the coronary arteries by SEM and micro CT, and also compared the neovascularization at the media and adventitia of the aorta by an immunohistochemical analysis. RESULTS: As previously reported, obvious inflammation was detected two weeks after the injection of CAWS, and also intimal thickening was observed three weeks after the injection. We found that the vasa vasorum in the adventitia of the aorta was increased in the model mice. The vasa vasorum started increasing one week after the injection of CAWS, before any obvious vasculitis was microscopically detected. CONCLUSION: The present results indicate that the vasculitis in Kawasaki disease starts as a disorder of the vasa vasorum.

Effects of HMG-CoA reductase inhibitors on continuous post-inflammatory vascular remodeling late after Kawasaki disease.

BACKGROUND: In Kawasaki disease (KD), it has been clinically and experimentally reported that post-inflammatory vascular remodeling would induce the development of arteriosclerosis or early onset of atherosclerosis in the future. The effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on continuous vascular remodeling late after Kawasaki disease were clinically evaluated. PATIENTS AND METHODS: We enrolled and treated a total of 11 KD patients (age range, 7-25 years) with fluvastatin (0.5-0.7 mg/kg/day) for 12 months. All of them had significant coronary aneurysmal or stenotic lesions and more than 3 of the following 5 abnormal findings: reduced %flow-mediated dilatation (%FMD), reduced urinary NOx, elevated high-sensitivity C-reactive protein (hs-CRP), reduced urinary 8-isoprostane, and elevated brachial-ankle pulse wave velocity (baPWV; control, ≤1400 cm/s). RESULTS: A statistically significant improvement was observed in each biomarker after fluvastatin treatment: %FMD, from 9.29% (3.41)% to 10.55% (3.27)% (p=0.003) after 3 months; NOx/creatinine (cre), from 1.16 (0.54) µmol/mg cre to 1.30 (0.50) µmol/mg cre (p=0.038) after 12 months; baPWV, from 1175.4 (277.3) cm/s to 1031.8 (155.6) cm/s (p=0.009) after 3 months; hs-CRP, from 0.073 (0.035) mg/dl to 0.028 (0.014) mg/dl (p=0.0002) after 3 months; and 8-iso/cre, from 751.8 (241.8) pg/mg cre to 660.0 (198.5) pg/mg cre (p=0.018) after 3 months. No adverse events were clinically observed in the patients. CONCLUSIONS: The results of this study suggested that HMG-CoA reductase inhibitors are useful as an alternative therapeutic strategy for stabilizing continuous post-inflammatory vascular remodeling that results in the development of arteriosclerosis late after KD or early onset of atherosclerosis in the future.

Rapidly progressive IgA nephropathy.

A 14-year-old boy presented with macroscopic hematuria and a rapid deterioration in renal function. Percutaneous renal biopsy demonstrated severe crescentic IgA nephropathy (IgAN) with extensive (88%) glomerular crescent formation. After started intravenous administration of high-dose pulse methylprednisolone, severe nausea and general malaise accompanied by a rapid increase in Blood Urea Nitrogen (BUN) and serum creatinine levels appeared, however, the renal function ameliorated rapidly and fully revovered by following oral administration of corticosteroid. The clinical presentation of our case seems to be very remarkable compared to previously reported cases of rapidly progressive IgAN.

Rapidly progressive IgA nephropathy.

A 14-year-old boy presented with macroscopic hematuria and a rapid deterioration in renal function. Percutaneous renal biopsy demonstrated severe crescentic IgA nephropathy (IgAN) with extensive (88%) glomerular crescent formation. After started intravenous administration of high-dose pulse methylprednisolone, severe nausea and general malaise accompanied by a rapid increase in Blood Urea Nitrogen (BUN) and serum creatinine levels appeared, however, the renal function ameliorated rapidly and fully recovered by following oral administration of corticosteroid. The clinical presentation of our case seems to be very remarkable compared to previously reported cases of rapidly progressive IgAN.

Role of tissue interaction between pineal primordium and neighboring tissues in avian pineal morphogenesis studied by intraocular transplantation.

Tissue interactions play an essential role in organogenesis during embryonic development. However, virtually no attempts have been made to study the role of tissue interaction in pineal development. In the present study we examined the inductive role of the epidermis and mesenchyme in the morphogenesis of quail pineal glands. The pineal rudiment is first observed at embryonic day 2 (E2: 2 days of incubation) at the dorsal midline of the diencephalon as a short semi-spherical protrusion. Electron microscopic observations revealed that no mesenchymal cells are found between the epidermis and the distal end of the E2 pineal primordium but that a thin layer of mesenchymal cells separate the epidermis from the pineal primordium at E3. Small pieces containing pineal rudiment were cut off from E2 or E3 embryos. They were treated with enzymes to eliminate the epidermis and/or mesenchyme, grafted into E5 chicken eyes, and cultured there for 1 week. When E3 pineal rudiment was treated with Dispase to remove the epidermis, the pineal gland developed normally. When the rudiment was further treated with collagenase to remove the surrounding mesenchymal cells, a multi-follicular structure was still formed, but to a lesser extent than when rudiments were treated with Dispase alone. When E2 quail pineal rudiment with the epidermis was grafted without any treatment, a multi-follicular structure developed which morphologically resembled embryonic pineal organs. When the epidermis was removed from E2 rudiments by Dispase, a single large vesicular structure was formed. These results suggest that the overlying epidermis and/or mesenchymal cells play some inductive role in the initial pineal development, while the mesenchymal tissue plays an important role in pineal follicular formation later during development. Since only a few experimental studies have been done to examine pineal morphogenesis, the present study provides fundamental insights into avian pineal development.

Rapidly progressive IgA nephropathy.

A 14-year-old boy presented with macroscopic hematuria and a rapid deterioration in renal function. Percutaneous renal biopsy demonstrated severe crescentic IgA nephropathy (IgAN) with extensive (88%) glomerular crescent formation. After started intravenous administration of high-dose pulse methylprednisolone, severe nausea and general malaise accompanied by a rapid increase in Blood Urea Nitrogen (BUN) and serum creatinine levels appeared, however, the renal function ameliorated rapidly and fully recovered by following oral administration of corticosteroid. The clinical presentation of our case seems to be very remarkable compared to previously reported cases of rapidly progressive IgAN.