Gelatinolytic activity of autocrine matrix metalloproteinase-9 leads to endothelial de-arrangement in Moyamoya disease.

Moyamoya disease (MMD) is a rare steno-occlusive cerebrovascular disorder. Mechanisms driving the formation of aberrant MMD vessels remain elusive. We collected serum and vessel specimens from MMD and atherosclerotic cerebrovascular disease (ACVD) patients serving as controls due to the same hypoxic stimulus but substantial differences in terms of vascular features. Based on patient material and an in vitro model mimicking ACVD and MMD conditions, matrix metalloproteinase-9 (MMP-9) and vascular-endothelial growth factor (VEGF) were tested for their potential involvement in cerebrovascular disintegration. While serum concentration of both molecules did not significantly differ in both patient groups, excessive collagenase activity and lowered collagen IV protein amount in MMD vessels pointed to a focal MMP-9 activity at the affected vessel sites. We observed overexpressed and autocrinely secreted MMP-9 and VEGF along with disturbances of EC-matrix interactions in MMD but not ACVD serum-treated cEND cells. These seemingly brain-specific effects were partially attenuated by VEGF signaling inhibition suggesting its role in the MMD etiology. In conclusion, our findings support the understanding of the high incidence of hemorrhagic and ischemic events in MMD and provide the basis for novel therapeutic strategies stopping or slowing the development of fragile cerebrovasculature or micro-bleeds characterizing the disease.

De novo mutations in CBL causing early-onset paediatric moyamoya angiopathy.

BACKGROUND: Moyamoya angiopathy (MMA) is characterised by a progressive stenosis of the terminal part of the internal carotid arteries and the development of abnormal collateral deep vessels. Its pathophysiology is unknown. MMA can be the sole manifestation of the disease (moyamoya disease) or be associated with various conditions (moyamoya syndrome) including some Mendelian diseases. We aimed to investigate the genetic basis of moyamoya using a whole exome sequencing (WES) approach conducted in sporadic cases without any overt symptom suggestive of a known Mendelian moyamoya syndrome. METHODS: A WES was performed in four unrelated early-onset moyamoya sporadic cases and their parents (trios). Exome data were analysed under dominant de novo, autosomal recessive and X-linked hypotheses. A panel of 17 additional sporadic cases with early-onset moyamoya was available for mutation recurrence analysis. RESULTS: We identified two germline de novo mutations in CBL in two out of the four trio probands, two girls presenting with an infancy-onset severe MMA. Both mutations were predicted to alter the ubiquitin ligase activity of the CBL protein that acts as a negative regulator of the RAS pathway. These two germline CBL mutations have previously been described in association with a developmental Noonan-like syndrome and susceptibility to juvenile myelomonocytic leukaemia (JMML). Notably, the two mutated girls never developed JMML and presented only subtle signs of RASopathy that did not lead to evoke this diagnosis during follow-up. CONCLUSIONS: These data suggest that CBL gene screening should be considered in early-onset moyamoya, even in the absence of obvious signs of RASopathy.

Significance of cyclooxygenase-2 elevation in middle cerebral artery for patients with hemorrhagic moyamoya disease.

The etiology and pathogenesis of moyamoya disease (MMD) remain elusive. Some inflammatory proteins, such as cyclooxygenase (COX)-2, are believed to be implicated in the development of MMD. So far, the relationship between COX-2 and MMD is poorly understood and reports on the intracranial vessels of MMD patients are scanty. In this study, tiny pieces of middle cerebral artery (MCA) and superficial temporal artery (STA) from 13 MMD patients were surgically harvested. The MCA and STA samples from 5 control patients were also collected by using the same technique. The expression of COX-2 was immunohistochemically detected and the average absorbance (A) of positively-stained areas was measured. High-level COX-2 expression was found in all layers of the MCA samples from all 5 hemorrhagic MMD patients, while positive but weak expression of COX-2 was observed only in the endothelial layer of the MCA samples from most ischemic MMD patients (6/8, 75%). The average A values of COX-2 in the hemorrhagic MMD patients were substantially higher than those in their ischemic counterparts (t=4.632, P=0.001). There was no significant difference in the COX-2 expression among the "gender" groups, or "radiographic grade" groups, or "lesion location" groups (P>0.05 for all). The COX-2 expression was detected neither in the MCA samples from the controls nor in all STA specimens. Our results suggested that COX-2 was up-regulated in the MCA of MMD patients, especially in hemorrhagic MMD patients. We are led to speculate that COX-2 may be involved in the pathogenesis of MMD and even contribute to the hemorrhagic stroke of MMD patients.

Biochemical and Functional Characterization of RNF213 (Mysterin) R4810K, a Susceptibility Mutation of Moyamoya Disease, in Angiogenesis In Vitro and In Vivo.

BACKGROUND: P.R4810K of RNF213 (mysterin: rs112735431), which is an AAA(+) ATPase, is the susceptibility polymorphism for moyamoya disease (MMD) in East Asians. However, the role of RNF213 R4810K in the etiology of MMD is unknown. METHODS AND RESULTS: To clarify the role of RNF213 in known angiogenic pathways, RNF213 expression was analyzed in endothelial cells (ECs) treated with several angiogenic and antiangiogenic factors, including interferons (IFNs). RNF213 was upregulated by IFN-ß through signal transducer and activator of transcription x in the promoter and mediated antiangiogenic activity of IFN-ß. RNF213 wild-type (WT) overexpression could not lower angiogenesis without IFN-ß, but RNF213 R4810K overexpression could. To correlate biochemical function as ATPase and the role of RNF213 oligomer formation with antiangiogenic activity, we investigated the effects of mutations in the AAA(+) module. A mutation of the Walker B motif (WEQ), which stabilizes oligomerization, inhibited angiogenesis, but AAA(+) module deletion, which cannot initiate oligomerization, did not. Intriguingly, R4810K, similar to WEQ, decreased ATPase activity, suggesting its antiangiogenic activity through stabilizing oligomers. To confirm the antiangiogenic effect of RNF213 upregulation in vivo, vascular EC- or smooth muscle cell-specific Rnf213 R4757K (R4810K ortholog) or WT transgenic (Tg) mice were exposed to hypoxia. Cerebral angiogenesis by hypoxia was suppressed in EC-specific Rnf213 R4757K Tg mice, whereas it was not suppressed in other mice. CONCLUSIONS: This study suggests the importance of inflammatory signals as environmental factors and R4810K carriers for susceptibility to cerebral hypoxia. A specific inhibitor of ATP binding to the first AAA(+) could be a promising therapeutic candidate for MMD.

Deregulation of Retinaldehyde Dehydrogenase 2 Leads to Defective Angiogenic Function of Endothelial Colony-Forming Cells in Pediatric Moyamoya Disease.

OBJECTIVE--: Moyamoya disease (MMD) is a common cause of childhood stroke, in which the abnormal function of the endothelial colony-forming cell (ECFC) plays a key role in the pathogenesis of the disease. This study was designed to identify genes involved in MMD pathogenesis using gene expression profiling and to understand the defective function of MMD ECFCs. APPROACH AND RESULTS--: We compared gene expression profiles of ECFCs isolated from patients with MMD and normal controls. Among the differentially expressed genes, we selected a gene with the most downregulated expression, retinaldehyde dehydrogenase 2 (RALDH2). The activity of RALDH2 in MMD ECFCs was assessed by in vitro tube formation assay and in vivo Matrigel plug assay in the presence of all-trans retinoic acid. The transcriptional control of RALDH2 was tested using ChIP assays on acetyl-histone H3. In the results, MMD ECFCs inefficiently formed capillary tubes in vitro and capillaries in vivo, a defect restored by all-trans retinoic acid treatment. Knockdown of RALDH2 mRNA in normal ECFCs also induced decreased activity of capillary formation in vitro. The decreased level of RALDH2 mRNA in MMD ECFCs was attributed to defective acetyl-histone H3 binding to the promoter region. CONCLUSIONS--: From these results, we conclude that the expression of RALDH2 was epigenetically suppressed in ECFCs from patients with MMD, which may play a key role in their functional impairment.

Increased vascular MMP-9 in mice lacking RNF213: moyamoya disease susceptibility gene.

Moyamoya disease (MMD) is a chronic occlusive cerebrovascular disease with unknown etiology. Recent genetic studies have identified RNF213 as an important susceptibility gene for MMD. To evaluate the role of RNF213 in vascular remodeling, RNF213 knockout mice (RNF213-/-) and their wild-type littermates (WT) were subjected to common carotid artery ligation to induce vascular hyperplasia. We examined the vascular expression of matrix metalloproteinase (MMP)-9, known to be increased in MMD. MMP-9 expression was significantly higher in RNF213-/- mice than in wild-type mice 1 and 7 days after common carotid artery ligation. The vascular wall was significantly thinner in RNF213-/- mice at 14 days. The increased vascular expression of MMP-9 and subsequent vascular wall thinning in RNF213-/- mice could reflect the early characteristic of MMD, consistent with the recently proposed constrictive remodeling theory.

Association of a functional polymorphism in the MMP-3 gene with Moyamoya Disease in the Chinese Han population.

BACKGROUND: Moyamoya disease (MMD) is an uncommon cerebrovascular disease characterized by progressive stenosis of the intracranial internal carotid arteries and their proximal branches. The important role of genetic factors in the etiology and pathogenesis of MMD is being increasingly recognized. The study was designed to examine the association of single nucleotide polymorphisms in matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinase (TIMP) genes with MMD occurrence. METHODS: A case-control study was performed. Five functional promoter polymorphisms in the MMP-2, MMP-3, MMP-9 and MMP-13 genes and a potentially functional promoter polymorphism in the TIMP-2 gene were determined by polymerase chain reaction-restriction fragment length polymorphism. Their associations with MMD were analyzed by multivariate logistic regression. RESULTS: In total, 208 definite patients with MMD (including 31 familial MMD, FMMD, patients) and 224 healthy subjects were recruited. The frequency of the MMP-3 5A/6A and 5A/5A genotypes was significantly lower in MMD patients (OR = 0.57, 95% CI 0.38-0.86, p(corr) = 0.042) compared with healthy controls in a dominant genetic model. Significant differences of the MMP-3 5A/6A polymorphism were also detected between FMMD patients and controls both in the dominant genetic model (OR = 0.23, 95% CI 0.08-0.68, p(corr) = 0.048) and the additive genetic model (OR = 0.24, 95% CI 0.08-0.69, p(corr) = 0.048). CONCLUSION: The functional polymorphism in the MMP-3 promoter might be associated with susceptibility to both MMD and FMMD in the Chinese Han population. The findings need to be validated in further studies including more subjects from different populations.

Increased expression of serum Matrix Metalloproteinase-9 in patients with moyamoya disease.

BACKGROUND: Moyamoya disease is a chronic occlusive cerebrovascular disease with unknown etiology characterized by an abnormal vascular network at the base of the brain, which can manifest both as ischemic stroke and as cerebral hemorrhage. It was also reported that the patients with moyamoya disease are more vulnerable to cerebral hyperperfusion such as postoperative hemorrhagic complication after extracranial-intracranial bypass surgery despite its low flow revascularization. However, the underlying mechanisms of its pathologic angiogenesis and the occurrence of hemorrhage are undetermined. Excessive degradation of the vascular matrix by MMPs, proteolytic enzymes that degrade all the components of extracellular matrix, can lead to instability of the vascular structure and can thereby cause bleeding. The MMPs also play an important role in tissue remodeling including angiogenesis in both physiologic and pathologic condition. METHODS: We examined the serum levels of MMP-2 and MMP-9 in 16 cases with definitive moyamoya disease by enzyme-linked immunosorbent assay and compared them with those from healthy controls. RESULTS: The serum MMP-9 level was significantly higher in moyamoya disease (40.18 ng/mL) than in healthy controls (13.75 ng/mL, P = .0372). There was no difference in serum MMP-2 level between moyamoya disease (646.65 ng/mL) and healthy control (677.60 ng/mL). Immunohistochemistry on the surgical specimens showed significant increase in MMP-9 expression within the arachnoid membrane of moyamoya disease. CONCLUSION: The increased expression of MMP-9 may contribute to pathologic angiogenesis and/or to the instability of the vascular structure and could thereby cause hemorrhage in moyamoya disease.

Moya moya syndrome in a child with pyruvate kinase deficiency and combined prothrombotic factors.

A 13-year-old Greek girl with pyruvate kinase deficiency and moya moya angiographic pattern is reported. She also had raised serum lipoprotein (a) concentration and was homozygous for the C677T mutation of the methylenetetrahydrofolate reductase gene. She presented with neonatal onset of anemia, hemolytic and aplastic crises, especially during infections, stroke, and also progressive motor and mental deterioration. A digital cranial angiography at 13 years revealed the typical angiographic findings of moya moya angiopathy. This is likely the first patient with pyruvate kinase deficiency and moya moya syndrome and also the combination of elevated serum lipoprotein (a) concentration and the C677T mutation of the methylenetetrahydrofolate reductase gene to be reported. In patients with pyruvate kinase deficiency and moya moya syndrome, a search for raised serum lipoprotein (a) concentrations and the C677T mutation of the methylenetetrahydrofolate reductase gene should be considered.

Caspase-3-dependent apoptosis in middle cerebral arteries in patients with moyamoya disease.

OBJECTIVE: Moyamoya disease (MMD) is a cerebrovascular occlusive disease characterized by progressive stenosis or occlusion at the distal ends of bilateral internal arteries. In MMD, a decreased number of medial smooth muscle cells in these vessels was previously reported. In this study focusing on the mechanism of remodeling in intracranial arterial walls of patients with MMD, we first collected tiny pieces of the wall of the middle cerebral artery (MCA) from patients with MMD and then analyzed them by immunohistochemical methods. METHODS: Ten patients underwent surgical procedures for the treatment of standard indications of MMD at Kyoto University Hospital. Specimens of MCA were obtained from these MMD patients during the surgical procedures. MCA samples were also obtained in the same way from control patients. The samples were analyzed by immunohistochemical methods. RESULTS: MCA specimens from MMD patients had a thinner media than control specimens. Immunoreactivities indicating single-stranded DNA and cleaved caspase-3 were higher in MMD samples than in control ones and were located in the smooth muscle cells of the media. CONCLUSION: Our results indicate that apoptosis, as evidenced by activated caspase-3, occurred in the media of the MCA of MMD patients. Thus, the MCA specimens from MMD patients had thinner vascular walls than specimens from controls.

Impaired NADH-CoQ reductase activity in a child with moyamoya syndrome.

A 33-month-old boy with recurrent stroke-like episodes had angiographic features characteristic of moyamoya syndrome. Mitochondrial encephalomyopathy was suspected because of lactic acidosis and ptosis. Studies of oxidative metabolism on isolated skeletal muscle mitochondria revealed impairment of NADH-coenzyme Q reductase activity. Mitochondrial metabolic disorders may cause moyamoya syndrome when other known associated factors are absent.