The discriminative role of PROX-1 immunohistochemistry between venous malformation and lymphatic malformation of the deep type with no visible diagnostic surface skin lesion

BACKGROUND

Venous malformations (VMs) are distinguished from lymphatic malformations (LMs) when specific diagnostic skin lesions are present. In the deep type, this is difficult by clinico-radiologic evaluation alone. We aimed to investigate the usefulness of lymphatic vessel endothelial cell (LEC) markers for the differential diagnosis of the deep VMs and LMs.

METHODS

A retrospective study was conducted based on the medical records of patients with VMs and LMs who underwent biopsy with both D2-40 and PROX-1 immunohistochemistry. We compared the initial clinico-radiological diagnosis with the final pathological diagnosis and identified which ones showed a difference.

RESULTS

From 261 patients who had VMs and LMs, 111 remained after the exclusion of those who showed definite surface diagnostic features. After pathological diagnosis with the expressions of D2-40 and PROX-1, 38 of 111 (34.2%) patients' final diagnoses were changed. Among these 38 cases, diagnosis was not changed by D2-40 positivity alone, but changed by PROX-1 positivity alone (52.6%) or by both (47.4%). The diagnostic changes were more frequent in the deep category (43.7%) than in the superficial category.

CONCLUSIONS

Identifying the expression of D2-40, and especially PROX-1, in the differential diagnosis of VMs and LMs may provide important treatment guidelines and understanding their natural course.

Arteriovenous malformation Map2k1 mutation affects vasculogenesis

Somatic activating MAP2K1 mutations in endothelial cells (ECs) cause extracranial arteriovenous malformation (AVM). We previously reported the generation of a mouse line allowing inducible expression of constitutively active MAP2K1 (p.K57N) from the Rosa locus (R26GT-Map2k1-GFP/+) and showed, using Tg-Cdh5CreER, that EC expression of mutant MAP2K1 is sufficient for the development of vascular malformations in the brain, ear, and intestines. To gain further insight into the mechanism by which mutant MAP2K1 drives AVM development, we induced MAP2K1 (p.K57N) expression in ECs of postnatal-day-1 pups (P1) and investigated the changes in gene expression in P9 brain ECs by RNA-seq. We found that over-expression of MAP2K1 altered the transcript abundance of > 1600 genes. Several genes had > 20-fold changes between MAP2K1 expressing and wild-type ECs; the highest were Col15a1 (39-fold) and Itgb3 (24-fold). Increased expression of COL15A1 in R26GT-Map2k1-GFP/+; Tg-Cdh5CreER+/- brain ECs was validated by immunostaining. Ontology showed that differentially expressed genes were involved in processes important for vasculogenesis (e.g., cell migration, adhesion, extracellular matrix organization, tube formation, angiogenesis). Understanding how these genes and pathways contribute to AVM formation will help identify targets for therapeutic intervention.

Microphysiological model of PIK3CA-driven vascular malformations reveals a role of dysregulated Rac1 and mTORC1/2 in lesion formation

Somatic activating mutations of PIK3CA are associated with development of vascular malformations (VMs). Here, we describe a microfluidic model of PIK3CA-driven VMs consisting of human umbilical vein endothelial cells expressing PIK3CA activating mutations embedded in three-dimensional hydrogels. We observed enlarged, irregular vessel phenotypes and the formation of cyst-like structures consistent with clinical signatures and not previously observed in cell culture models. Pathologic morphologies occurred concomitant with up-regulation of Rac1/p21-activated kinase (PAK), mitogen-activated protein kinase cascades (MEK/ERK), and mammalian target of rapamycin (mTORC1/2) signaling networks. We observed differential effects between alpelisib, a PIK3CA inhibitor, and rapamycin, an mTORC1 inhibitor, in mitigating matrix degradation and network topology. While both were effective in preventing vessel enlargement, rapamycin failed to reduce MEK/ERK and mTORC2 activity and resulted in hyperbranching, while inhibiting PAK, MEK1/2, and mTORC1/2 mitigates abnormal growth and vascular dilation. Collectively, these findings demonstrate an in vitro platform for VMs and establish a role of dysregulated Rac1/PAK and mTORC1/2 signaling in PIK3CA-driven VMs.

Somatic GJA4 gain-of-function mutation in orbital cavernous venous malformations

Orbital cavernous venous malformation (OCVM) is a sporadic vascular anomaly of uncertain etiology characterized by abnormally dilated vascular channels. Here, we identify a somatic missense mutation, c.121G > T (p.Gly41Cys) in GJA4, which encodes a transmembrane protein that is a component of gap junctions and hemichannels in the vascular system, in OCVM tissues from 25/26 (96.2%) individuals with OCVM. GJA4 expression was detected in OCVM tissue including endothelial cells and the stroma, through immunohistochemistry. Within OCVM tissue, the mutation allele frequency was higher in endothelial cell-enriched fractions obtained using magnetic-activated cell sorting. Whole-cell voltage clamp analysis in Xenopus oocytes revealed that GJA4 c.121G > T (p.Gly41Cys) is a gain-of-function mutation that leads to the formation of a hyperactive hemichannel. Overexpression of the mutant protein in human umbilical vein endothelial cells led to a loss of cellular integrity, which was rescued by carbenoxolone, a non-specific gap junction/hemichannel inhibitor. Our data suggest that GJA4 c.121G > T (p.Gly41Cys) is a potential driver gene mutation for OCVM. We propose that hyperactive hemichannel plays a role in the development of this vascular phenotype.

Downregulation of microRNA-21 contributes to decreased collagen expression in venous malformations via transforming growth factor-β/Smad3/microRNA-21 signaling feedback loop

OBJECTIVE

Venous malformations (VMs) are the most frequent vascular malformations and are characterized by dilated and tortuous veins with a dysregulated vascular extracellular matrix. The purpose of the present study was to investigate the potential involvement of microRNA-21 (miR-21), a multifunctional microRNA tightly associated with extracellular matrix regulation, in the pathogenesis of VMs.

METHODS

The expression of miR-21, collagen I, III, and IV, transforming growth factor-β (TGF-β), and Smad3 (mothers against decapentaplegic homolog 3) was evaluated in VMs and normal skin tissue using in situ hybridization, immunohistochemistry, Masson trichrome staining, and real-time polymerase chain reaction. Human umbilical vein endothelial cells (HUVECs) were used to explore the underlying mechanisms.

RESULTS

miR-21 expression was markedly decreased in the VM specimens compared with normal skin, in parallel with downregulation of collagen I, III, and IV and the TGF-β/Smad3 pathway in VMs. Moreover, our data demonstrated that miR-21 positively regulated the expression of collagens in HUVECs and showed a positive association with the TGF-β/Smad3 pathway in the VM tissues. In addition, miR-21 was found to mediate TGF-β-induced upregulation of collagens in HUVECs. Our data have indicated that miR-21 and the TGF-β/Smad3 pathway could form a positive feedback loop to synergistically regulate endothelial collagen synthesis. In addition, TGF-β/Smad3/miR-21 feedback loop signaling was upregulated in bleomycin-treated HUVECs and VM specimens, which was accompanied by increased collagen deposition.

CONCLUSIONS

To the best of our knowledge, the present study has, for the first time, revealed downregulation of miR-21 in VMs, which might contribute to decreased collagen expression via the TGF-β/Smad3/miR-21 signaling feedback loop. These findings provide new information on the pathogenesis of VMs and might facilitate the development of new therapies for VMs.

Defective Flow-Migration Coupling Causes Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Activin receptor-like kinase 1 (ALK1) is an endothelial transmembrane serine threonine kinase receptor for BMP family ligands that plays a critical role in cardiovascular development and pathology. Loss-of-function mutations in the ALK1 gene cause type 2 hereditary hemorrhagic telangiectasia, a devastating disorder that leads to arteriovenous malformations. Here, we show that ALK1 controls endothelial cell polarization against the direction of blood flow and flow-induced endothelial migration from veins through capillaries into arterioles.

METHODS

Using Cre lines that recombine in different subsets of arterial, capillary-venous, or endothelial tip cells, we show that capillary-venous Alk1 deletion was sufficient to induce arteriovenous malformation formation in the postnatal retina.

RESULTS

ALK1 deletion impaired capillary-venous endothelial cell polarization against the direction of blood flow in vivo and in vitro. Mechanistically, ALK1-deficient cells exhibited increased integrin signaling interaction with vascular endothelial growth factor receptor 2, which enhanced downstream YAP/TAZ nuclear translocation. Pharmacologic inhibition of integrin or YAP/TAZ signaling rescued flow migration coupling and prevented vascular malformations in Alk1-deficient mice.

CONCLUSIONS

Our study reveals ALK1 as an essential driver of flow-induced endothelial cell migration and identifies loss of flow-migration coupling as a driver of arteriovenous malformation formation in hereditary hemorrhagic telangiectasia disease. Integrin-YAP/TAZ signaling blockers are new potential targets to prevent vascular malformations in patients with hereditary hemorrhagic telangiectasia.

Venous malformation vessels are improperly specified and hyperproliferative

Venous malformations (VMs) are slow-flow malformations of the venous vasculature and are the most common type of vascular malformation with a prevalence of 1%. Germline and somatic mutations have been shown to contribute to VM pathogenesis, but how these mutations affect VM pathobiology is not well understood. The goal of this study was to characterize VM endothelial and mural cell expression by performing a comprehensive expression analysis of VM vasculature. VM specimens (n = 16) were stained for pan-endothelial, arterial, venous, and endothelial progenitor cell proteins; proliferation was assessed with KI67. Endothelial cells in the VM vessels were abnormally orientated and improperly specified, as seen by the misexpression of both arterial and endothelial cell progenitor proteins not observed in control vessels. Consistent with arterialization of the endothelial cells, VM vessels were often surrounded by multiple layers of disorganized mural cells. VM endothelium also had a significant increase in proliferative endothelial cells, which may contribute to the dilated channels seen in VMs. Together the expression analysis indicates that the VM endothelium is misspecified and hyperproliferative, suggesting that VMs are biologically active lesions, consistent with clinical observations of VM progression over time.

The Noonan Syndrome Gene Lztr1 Controls Cardiovascular Function by Regulating Vesicular Trafficking

RATIONALE

Noonan syndrome (NS) is one of the most frequent genetic disorders. Bleeding problems are among the most common, yet poorly defined complications associated with NS. A lack of consensus on the management of bleeding complications in patients with NS indicates an urgent need for new therapeutic approaches.

OBJECTIVE

Bleeding disorders have recently been described in patients with NS harboring mutations of LZTR1 (leucine zipper-like transcription regulator 1), an adaptor for CUL3 (CULLIN3) ubiquitin ligase complex. Here, we assessed the pathobiology of LZTR1-mediated bleeding disorders.

METHODS AND RESULTS

Whole-body and vascular specific knockout of Lztr1 results in perinatal lethality due to cardiovascular dysfunction. Lztr1 deletion in blood vessels of adult mice leads to abnormal vascular leakage. We found that defective adherent and tight junctions in Lztr1-depleted endothelial cells are caused by dysregulation of vesicular trafficking. LZTR1 affects the dynamics of fusion and fission of recycling endosomes by controlling ubiquitination of the ESCRT-III (endosomal sorting complex required for transport III) component CHMP1B (charged multivesicular protein 1B), whereas NS-associated LZTR1 mutations diminish CHMP1B ubiquitination. LZTR1-mediated dysregulation of CHMP1B ubiquitination triggers endosomal accumulation and subsequent activation of VEGFR2 (vascular endothelial growth factor receptor 2) and decreases blood levels of soluble VEGFR2 in Lztr1 haploinsufficient mice. Inhibition of VEGFR2 activity by cediranib rescues vascular abnormalities observed in Lztr1 knockout mice Conclusions: Lztr1 deletion phenotypically overlaps with bleeding diathesis observed in patients with NS. ELISA screening of soluble VEGFR2 in the blood of LZTR1-mutated patients with NS may predict both the severity of NS phenotypes and potential responders to anti-VEGF therapy. VEGFR inhibitors could be beneficial for the treatment of bleeding disorders in patients with NS.

Multifaced Roles of the αvβ3 Integrin in Ehlers-Danlos and Arterial Tortuosity Syndromes' Dermal Fibroblasts

The αvβ3 integrin, an endothelial cells’ receptor-binding fibronectin (FN) in the extracellular matrix (ECM) of blood vessels, regulates ECM remodeling during migration, invasion, angiogenesis, wound healing and inflammation, and is also involved in the epithelial mesenchymal transition. In vitro-grown human control fibroblasts organize a fibrillar network of FN, which is preferentially bound on the entire cell surface to its canonical α5β1 integrin receptor, whereas the αvβ3 integrin is present only in rare patches in focal contacts. We report on the preferential recruitment of the αvβ3 integrin, due to the lack of FN–ECM and its canonical integrin receptor, in dermal fibroblasts from Ehlers–Danlos syndromes (EDS) and arterial tortuosity syndrome (ATS), which are rare multisystem connective tissue disorders. We review our previous findings that unraveled different biological mechanisms elicited by the αvβ3 integrin in fibroblasts derived from patients affected with classical (cEDS), vascular (vEDS), hypermobile EDS (hEDS), hypermobility spectrum disorders (HSD), and ATS. In cEDS and vEDS, respectively, due to defective type V and type III collagens, αvβ3 rescues patients’ fibroblasts from anoikis through a paxillin-p60Src-mediated cross-talk with the EGF receptor. In hEDS and HSD, without a defined molecular basis, the αvβ3 integrin transduces to the ILK-Snail1-axis inducing a fibroblast-to-myofibroblast-transition. In ATS cells, the deficiency of the dehydroascorbic acid transporter GLUT10 leads to redox imbalance, ECM disarray together with the activation of a non-canonical αvβ3 integrin-TGFBRII signaling, involving p125FAK/p60Src/p38MAPK. The characterization of these different biological functions triggered by αvβ3 provides insights into the multifaced nature of this integrin, at least in cultured dermal fibroblasts, offering future perspectives for research in this field.

Fibulin-4 is essential for maintaining arterial wall integrity in conduit but not muscular arteries

Homozygous or compound heterozygous mutations in fibulin-4 (FBLN4) lead to autosomal recessive cutis laxa type 1B (ARCL1B), a multisystem disorder characterized by significant cardiovascular abnormalities, including abnormal elastin assembly, arterial tortuosity, and aortic aneurysms. We sought to determine the consequences of a human disease-causing mutation in FBLN4 (E57K) on the cardiovascular system and vascular elastic fibers in a mouse model of ARCL1B. Fbln4E57K/E57K mice were hypertensive and developed arterial elongation, tortuosity, and ascending aortic aneurysms. Smooth muscle cell organization within the arterial wall of large conducting vessels was abnormal, and elastic fibers were fragmented and had a moth-eaten appearance. In contrast, vessel wall structure and elastic fiber integrity were normal in resistance/muscular arteries (renal, mesenteric, and saphenous). Elastin cross-linking and total elastin content were unchanged in large or small arteries, whereas elastic fiber architecture was abnormal in large vessels. While the E57K mutation did not affect Fbln4 mRNA levels, FBLN4 protein was lower in the ascending aorta of mutant animals compared to wild-type arteries but equivalent in mesenteric arteries. We found a differential role of FBLN4 in elastic fiber assembly, where it functions mainly in large conduit arteries. These results suggest that elastin assembly has different requirements depending on vessel type. Normal levels of elastin cross-links in mutant tissue call into question FBLN4's suggested role in mediating lysyl oxidase-elastin interactions. Future studies investigating tissue-specific elastic fiber assembly may lead to novel therapeutic interventions for ARCL1B and other disorders of elastic fiber assembly.

[Expression of matrix metalloproteinases and their inhibitors in the internal carotid artery wall in pathological tortuosity]

The principal morphological sign of fibromuscular dysplasia in pathological tortuosity (PT) of the internal carotid artery (ICA) is the fragmentation of elastic fibers that are degraded by matrix metalloproteinases 2 and 9 (MMP-2, MMP-9). Nevertheless, the role of MMPs and their inhibitors in the pathogenesis of ICA PT remains completely unexplored.

AIM

to investigate the expression of elastin-degrading MMPs and their inhibitors in the wall of the ICA in PT by immunohistochemistry and confocal laser scanning microscopy.

METHODS

Immunohistochemical examination was made using antibodies to MMP-2, MMP-9 and their tissue inhibitors TIMP-1 and TIMP-2. MMP-9 and TIMP-1 levels were determined by confocal laser scanning microscopy.

RESULTS

Immunohistochemical examination revealed a statistically significant predominance of high concentrations of MMP-2 and MMP-9 and a low level of their inhibitor TIMP-1 in ICA PT, while simultaneous obvious accumulation of both markers was most often identified in the control group (p<0.05). Analysis of MMP-2/TIMP-2 and MMP-9/TIMP-2 ratios showed the prevalence of the simultaneously high expression of both proteins in ICA PT and in the control group too. The similar data were also obtained by confocal microscopy: the control group showed elevated MMP-9 and TIMP-1 expressions and the ICA PT control displayed a high proteinase and low inhibitor levels (p<0.05).

CONCLUSION

Elastic fiber fragmentation in ICA PT is due to imbalance between MMPs and their inhibitors; namely, the prevalence of MMP-2 and MMP-9 over their inhibitor TIMP-1, which leads to the degradation of extracellular matrix components, primarily elastin.

Rapamycin improves TIE2-mutated venous malformation in murine model and human subjects

Venous malformations (VMs) are composed of ectatic veins with scarce smooth muscle cell coverage. Activating mutations in the endothelial cell tyrosine kinase receptor TIE2 are a common cause of these lesions. VMs cause deformity, pain, and local intravascular coagulopathy, and they expand with time. Targeted pharmacological therapies are not available for this condition. Here, we generated a model of VMs by injecting HUVECs expressing the most frequent VM-causing TIE2 mutation, TIE2-L914F, into immune-deficient mice. TIE2-L914F-expressing HUVECs formed VMs with ectatic blood-filled channels that enlarged over time. We tested both rapamycin and a TIE2 tyrosine kinase inhibitor (TIE2-TKI) for their effects on murine VM expansion and for their ability to inhibit mutant TIE2 signaling. Rapamycin prevented VM growth, while TIE2-TKI had no effect. In cultured TIE2-L914F-expressing HUVECs, rapamycin effectively reduced mutant TIE2-induced AKT signaling and, though TIE2-TKI did target the WT receptor, it only weakly suppressed mutant-induced AKT signaling. In a prospective clinical pilot study, we analyzed the effects of rapamycin in 6 patients with difficult-to-treat venous anomalies. Rapamycin reduced pain, bleeding, lesion size, functional and esthetic impairment, and intravascular coagulopathy. This study provides a VM model that allows evaluation of potential therapeutic strategies and demonstrates that rapamycin provides clinical improvement in patients with venous malformation.

A clinical, radiologic, and immunopathologic study of five periorbital intraosseous cavernous vascular malformations

PURPOSE

To correlate the clinical, radiographic, histopathologic, and immunohistochemical features of 5 primary periorbital intraosseous cavernous vascular malformations.

DESIGN

Retrospective interventional case series.

METHODS

Clinical and operative records and radiographic images were reviewed. Histopathologic slides were evaluated with hematoxylin-eosin, trichrome, and elastin stains. Immunohistochemical studies were performed with a spectrum of monoclonal antibodies directed at antigens of vascular cells.

RESULTS

Three men and 2 women ranged in age from 36 to 64 years. Vision was unaffected and there was no proptosis or globe displacement. The slow-growing lesions measured 13-25 mm in greatest diameter (mean 16.4 mm). Computed tomographic studies revealed that 2 lesions were situated in the maxillary bone, 2 in the frontal, and 1 in the zygoma, all anteriorly and with circumscribed, lucent, honeycombed, or sunburst characteristics. Histopathologically the lesions were composed of cavernous or telangiectatic channels; 1 showed advanced fibrotic vascular involution. Immunohistochemistry demonstrated CD31/34 positivity for vascular endothelium and D2-40 negativity for lymphatic endothelium. A typically thin mural myofibroblastic cuff was smooth muscle actin positive, weakly calponin positive, and desmin negative. Glucose transporter-1 and Ki-67 were negative in the endothelium.

CONCLUSIONS

Intraosseous vascular lesions resemble orbital cavernous venous malformations (not true hemangiomas), except that their vascular walls are thinner owing to the constraints imposed by neighboring bone spicules, which limit the amount of interstitium from which mural myofibroblasts can be recruited. The bony trabeculae conferred the honeycomb or sunburst appearances observed radiographically. En bloc excision of these lesions was successful and avoided complications (mean follow-up, 46 months).

Elk3 deficiency causes transient impairment in post-natal retinal vascular development and formation of tortuous arteries in adult murine retinae

Serum Response Factor (SRF) fulfills essential roles in post-natal retinal angiogenesis and adult neovascularization. These functions have been attributed to the recruitment by SRF of the cofactors Myocardin-Related Transcription Factors MRTF-A and -B, but not the Ternary Complex Factors (TCFs) Elk1 and Elk4. The role of the third TCF, Elk3, remained unknown. We generated a new Elk3 knockout mouse line and showed that Elk3 had specific, non-redundant functions in the retinal vasculature. In Elk3(−/−) mice, post-natal retinal angiogenesis was transiently delayed until P8, after which it proceeded normally. Interestingly, tortuous arteries developed in Elk3(−/−) mice from the age of four weeks, and persisted into late adulthood. Tortuous vessels have been observed in human pathologies, e.g. in ROP and FEVR. These human disorders were linked to altered activities of vascular endothelial growth factor (VEGF) in the affected eyes. However, in Elk3(−/−) mice, we did not observe any changes in VEGF or several other potential confounding factors, including mural cell coverage and blood pressure. Instead, concurrent with the post-natal transient delay of radial outgrowth and the formation of adult tortuous arteries, Elk3-dependent effects on the expression of Angiopoietin/Tie-signalling components were observed. Moreover, in vitro microvessel sprouting and microtube formation from P10 and adult aortic ring explants were reduced. Collectively, these results indicate that Elk3 has distinct roles in maintaining retinal artery integrity. The Elk3 knockout mouse is presented as a new animal model to study retinal artery tortuousity in mice and human patients.

Diagnostic utility of WT-1 cytoplasmic stain in variety of vascular lesions

Vascular lesions are commonly encountered in routine pathologic practice and often pose diagnostic challenges owing to their morphologic diversity. Although WT-1 expression was reported in some vascular tumors, little is known about its staining patterns in a spectrum of vascular lesions from various locations. We examined WT-1 immunostain in 95 cases of vascular lesions including angiosarcomas (AS, 19 cases), hemangioendotheliomas (HE, 5), Kaposi's sarcomas (KS, 4), cavernous hemangiomas (CVH, 12), capillary hemangiomas (CPH, 7), pyogenic granulomas (PG, 4), lymphangiomas (LA, 4), hemangiopericytomas (HP, 5), glomus tumors (GT, 8), vascular malformation (VM, 13) and granulation tissue (GRT, 14). Strong WT-1 cytoplasmic stain was invariably observed in all cases of malignant and borderline vascular tumors including AS (19/19), KS (4/4) and HE (5/5). WT-1 was also consistently expressed in CPH (7/7), PG (4/4), and GRT (14/14), while it became weaker in VM (10/13) and often negative in CVH (2/12) and LA (0/4). WT1 stain was not demonstrated in HP (0/5) and rarely in GT (2/8). We conclude that consistent and diffuse WT-1 cytoplasmic stain in AS, HE and KS can be useful in distinguishing these tumors from poorly differentiated tumors with mimicking features. On the other hand, reliable WT-1 stain in CPH, PG and GRT may help in differential diagnosis with non-endothelial vascular tumors such as GT and HP. Recognizing the WT-1 cytoplasmic stain in a broad spectrum of benign and neoplastic tissues is critical in formulating appropriate immunohistochemical panels and avoiding misinterpretation of results.

[The potential pathogenesis of gastrointestinal vascular malformation and the potential mechanism of thalidomide in the treatment of gastrointestinal vascular malformation]

OBJECTIVE

To study the pathogenesis of gastrointestinal vascular malformation (GIVM) and the potential mechanism of thalidomide in the treatment of gastrointestinal bleeding due to GIVM.

METHODS

We collected the surgical intestinal specimens from 10 patients who suffered from massive hemorrhage of gastrointestinal tract owning to GIVM and the normal intestinal mucosa around the lesions, as well as normal intestinal mucosa from healthy subjects. Immunohistochemical (IHC) staining was carried out to investigate the differences of angiopoietin 2 (Ang2), Notch1 and delta like ligand 4 (Dll4) in the above three intestinal mucosa to find the relationship with the pathogenesis of GIVM. Human umbilical vein endothelial cells (HUVECs) were cultured with 0, 25, 50, 100 and 200 mg/L thalidomide for 24 or 48 hours to observe their mRNA and protein expressions of Ang2, Notch1, Dll4 by real-time PCR and Western blot.

RESULTS

By IHC staining, more expressions of Ang2, Notch1 and Dll4 in the lesions were detected than those in the normal intestinal mucosa around the lesions and the normal intestinal mucosa in healthy people. The expressions of Ang2, Notch1 and Dll4 were significantly correlated (P = 0.016, r = 0.732), and the expressions of Notch1 and Dll4 were absolutely correlated (P = 0.000, r = 1.000). Real-time PCR and Western blot showed that thalidomide could down-regulate the expressions of them, which were in a concentration-dependent manner.

CONCLUSION

Ang2, Notch1 and Dll4 may correlate with the pathogenesis of GIVM, while thalidomide can concentration-dependently down-regulate the expression of Ang2, Notch1 and Dll4, which may be one of the mechanism that thalidomide play a therapeutic role in GIVM.

[Differential expression of CD133, Glut-1 in tissues and endothelial cells derived from infantile hemangioma and vascular malformation]

OBJECTIVE

To investigate the expression and significance of CD133, Glut-1 and precursor cell, placental microvessel endothelial cells in the occurrence, development and regression of infantile hemangiomas.

METHODS

We examined the expression and significance of CD133, Glut-1 in the occurrence, development and regression of infantile hemangiomas and congenital vascular malformation postnatal vascular malformation using immunohistochemical technique. An image analysis system (Image-pro plus 5.0) was used to measure the average integrated optical density and the rate of positive area of CD133 and Glut-i in different stages of hemangiomas and in vascular malformation.

RESULTS

The expression of CD133 was significantly higher in differential stages congenital hemangioma, congenital vascular malformation, placenta chorionic villi than postnatal vascular malformation (P < 0.05). About the expression of Glut-1, there was difference between proliferating hemangiomas, placenta and degenerating hemangiomas, vascular malformation (P < 0.05).

CONCLUSION

The precursor cells marked CD133 is the source of endothelial cells derived from congenital hemangiomas and congenital vascular malformation.

[The expression and role of glucose transporter-1 in infantile hemangioma]

OBJECTIVE

To investigate the expression and role of glucose transporter-1 (Glut1) in infantile hemangioma.

METHODS

Fifty-two samples from infantile hemangioma, 25 in cavernous venous malformation, 9 in arteriovenous malformation, 2 in capillary malformation and 5 in normal skin samples were involved in this study. The EnVision immunohistochemical stain was used to investigate the expression of Glut1 protein in these samples.

RESULTS

In the early proliferating stage, a number of endothelial cells expressed Glut1. In the middle proliferating stage, most of vascular endothelial cells and scattered endothelial cells expressed Glut1. In the late proliferating stage, the expression of Glut1 decreased quickly. In the involuting stage, all hemangioma samples didn't express Glut1. All of the samples from the cavernous venous malformations, arteriovenous malformations, capillary malformations and normal skin had no expression of Glut1.

CONCLUSIONS

Glut1 may be one of the phenotypes of infantile hemangioma endothelial cells in their development, rather than the inherent character. The expression of Glut1 changes according to the metabolic need of infantile hemangioma cells.

[Expression and significance of TRAIL protein and mRNA in hemangioma]

OBJECTIVE

To detect the expression of TRAIL protein and mRNA in hemangiomas and vascular malformations.

METHODS

Sections of 33 proliferative hemangiomas,28 involuting hemangiomas and 29 vascular malformations were immunostained for TRAIL protein, TRAIL mRNA was examined by in situ hybridization in these tissue.

RESULTS

The TRAIL protein positive rates in proliferative hemangiomas, involuting hemangiomas, vascular malformations and normal skins were respectively 45.45% (15/33), 78.57% (22/28), 0% and 0%. There were significant differences among the four pathologies (P < 0.01). The difference between proliferative hemangiomas and involuting hemangiomas was also significant (P < 0.01). The TRAIL mRNA positive rates were 66.67% (11/33), 89.29 (25/28), 0% and 0% respectively. There were also significant differences among the four pathologies (P < 0.01). The difference between proliferative hemangiomas and involuting hemangiomas was also significant (P < 0.01).

CONCLUSIONS

TRAIL could induce endothelial apoptosis and cause regression of hemangiomas.