Dlc1 controls cardio-vascular development downstream of Vegfa/Kdrl/Nrp1 signaling in the zebrafish embryo

ABSTRACTThe family of deleted-in-liver-cancer (dlc) genes encodes RhoGTPases and plays pivotal roles in cardiovascular development, but animal models for studying their functions are sparse due to early embryonic lethality. Gain and loss of function of dlc1 and dlc3 severely altered the growth of intersegmental vessels in the trunk of zebrafish embryos. Additionally, overexpression of dlc1 affected the growth of the common cardinal veins, but could rescue the arrest of angiogenesis induced by Vegfr2 inhibition, placing dlc1 downstream of kdrl signaling. Loss of dlc1 negatively affected the lumenization of the first aortic arch arteries and the lateral dorsal aortae. dlc1 mutants displayed a full obstruction in the early outflow tract during cardiac morphogenesis, which models to alterations in DLC1 detected in congenital heart defects in human patients. This study provides a functional in vivo characterization of dlc1 and dlc3 during vertebrate embryogenesis and places dlc1 as a key gene to control vascular development.

The cut-off values for the intima–media complex thickness assessed by colour Doppler sonography in seven cranial and aortic arch arteries

Objectives Colour Doppler sonography (CDS) is becoming ever more important in the diagnosis of GCA. Data on cut-off values for intima–media complex thickness (IMT) that can be used in clinical practice to distinguish between normal and inflamed arteries are limited. We aimed to derive potential cut-off values for IMT of seven preselected arteries by comparing IMT between GCA patients and a control group. Methods We performed CDS of the preselected temporal, facial, occipital, carotid, vertebral, subclavian and axillary arteries in consecutive newly diagnosed GCA patients between October 2013 and September 2019. A ‘halo’ with positive compression sign was considered a positive finding. We measured the maximum IMT in the preselected arteries and compared it with the maximum IMT of the control group. Results We were able to demonstrate a halo sign in at least one of the examined arteries of 244/248 (98.4%) GCA patients. Temporal arteries were the most commonly affected vessels, involved in 192 (77.4%) patients. We found extracranial large vessel involvement in 87 (35.1%) patients. The following cut-off values showed high levels of diagnostic accuracy: ≥0.4 mm for temporal, facial and occipital arteries, ≥0.7 mm for vertebral arteries, and ≥1 mm for carotid, subclavian and axillary arteries. Conclusion The involvement of a large array of arteries is easily and commonly detected by CDS and provides a high diagnostic yield in patients with suspected GCA. Proposed IMT cut-off values might further improve the diagnostic utility of CDS in these patients.

Anatomical Suitability of the Aortic Arch Arteries for a 3-Inner-Branch Arch Endograft

Purpose: To analyze aortic arch anatomy of patients who were already treated with a 2-inner-branch arch endograft (2-IBAE) in order to assess the anatomical suitability of the supra-aortic arteries as target vessels for a 3-IBAE. Materials and Methods: Three different configurations of the Cook Zenith Arch endograft were designed with distances of 110 mm (model 1), 90 mm (model 2), and 70 mm (model 3) between the orifices of the first and third inner branches. Preoperative measurements of the aortic arch anatomy from 104 consecutive patients treated electively with custom-made 2-IBAEs at 2 European centers between 2014 and 2019 were analyzed. A previously described standard methodology with a planning sheet was used. Data and measurements included the treatment indication for the aortic arch pathology, the type of landing zone, the type of arch, and the inner and outer lengths of the ascending aorta from the sinotubular junction to the innominate artery (IA). Additionally, the diameters and clock positions of the IA, left common carotid artery (LCCA), and left subclavian artery (LSA) were assessed, along with the distances between the IA and the LCCA, the IA and the LSA, and the distal landing zone. Results: Type I was the most common arch configuration (75/104, 72%). The mean clock positions were 12:30±00:28 for the IA, 12:00±00:23 for the LCCA, and 12:15±00:29 for the LSA. The mean diameters were 14.2±2.2 mm for the IA, 8.8±1.8 mm for the LCCA, and 10.5±2 mm for the LSA. The mean distances between the IA and LCCA and between the IA and LSA were 14.7±5.8 mm and 33±9.4 mm, respectively. Model 2 (branch distance 90 mm) had the highest suitability (79%), while models 1 and 3 showed suitability rates of 73% and 68%, respectively. The most frequent exclusion criterion in all models was the diameter of the LSA, followed by the IA to LSA distance. Conclusion: The suitability for a 3-IBAE among patients who had a 2-IBAE implanted is high, favoring a 90-mm distance between the retrograde LSA branch and baseline.

Early Embryonic Expression of AP-2α Is Critical for Cardiovascular Development

Congenital cardiovascular malformation is a common birth defect incorporating abnormalities of the outflow tract and aortic arch arteries, and mice deficient in the transcription factor AP-2α (Tcfap2a) present with complex defects affecting these structures. AP-2α is expressed in the pharyngeal surface ectoderm and neural crest at mid-embryogenesis in the mouse, but the precise tissue compartment in which AP-2α is required for cardiovascular development has not been identified. In this study we describe the fully penetrant AP-2α deficient cardiovascular phenotype on a C57Bl/6J genetic background and show that this is associated with increased apoptosis in the pharyngeal ectoderm. Neural crest cell migration into the pharyngeal arches was not affected. Cre-expressing transgenic mice were used in conjunction with an AP-2α conditional allele to examine the effect of deleting AP-2α from the pharyngeal surface ectoderm and the neural crest, either individually or in combination, as well as the second heart field. This, surprisingly, was unable to fully recapitulate the global AP-2α deficient cardiovascular phenotype. The outflow tract and arch artery phenotype was, however, recapitulated through early embryonic Cre-mediated recombination. These findings indicate that AP-2α has a complex influence on cardiovascular development either being required very early in embryogenesis and/or having a redundant function in many tissue layers.

FRI0193 ULTRASONOGRAPHY IN THE DIAGNOSIS OF GIANT CELL ARTERITIS

Background:Objectives:To evaluate the frequency of cranial and aortic arch artery involvement in GCA using color Doppler ultrasonography (CDS).Methods:We performed CDS of cranial and aortic arch arteries in 248 incipient, clinically diagnosed, GCA patients (64.9% females, median (IQR) age 75 (67-80) years) between October 2013 and September 2019, using a Philips IU22 with 5–17.5 MHz linear probe or Philips Epiq 7 with 5–18.5 MHz linear probe. Temporal, facial, occipital, carotid, vertebral, subclavian, and axillary arteries were examined bilaterally. A halo with positive compression sign was considered a positive finding. Additionally, the thickness of intima-media complex (IMT) of individual vessel was measured, and compared to the IMT of 97 consecutive suspected GCA cases (60.8% females median (IQR) age 74 (65-81) years), in whom GCA was excluded, that served as a control group.Results:The CDS was positive in 244 (98.4%) patients in at least one of the examined arteries. Temporal arteries were most commonly affected, and were involved in 192 (77.4%) patients, followed by facial and occipital arteries, involved in 122 (49.2) and 72 (29.0%) patients, respectively. Extracranial large vessel involvement (LVV) was found in 87 (35.1%) patients (32 patients had isolated LVV, and 55 concomitant cranial and LVV artery involvement). Among the 161 patients without LVV, 12 (4.8% of the studied cohort) had involvement of cranial arteries other than temporal arteries (we found facial and occipital artery involvement in 11 and 3 patients, respectively). Table 1 shows the frequency of individual vessel involvement in GCA, and the IMT of CDS inflamed and non-inflamed arteries in GCA, and in controls.Table 1.The involvement of cranial and aortic arch arteries in GCA assessed by CDS and intima-media thickness of inflamed and non-inflamed arteries in GCA, and controlsArteryGCA No (%)IMT (mm) in GCAIMT (mm) in ControlsPositive CDSPositive CDS*; minimalNegative CDSNegative CDS; maximalTemporal192 (77.4)0.71±0.19; 0.330.25±0.070.23±0.05; 0.46Facial122 (49.2)0.75±0.27; 0.410.29±0.070.26±0.07; 0.47Occipital72 (29.0)0.73±0.33; 0.450.26±0.060.23±0.05; 0.46Carotid34 (13.7)1.53±0.44; 0.880.78±0.180.72±0.15; 1.09Vertebral25 (10.1)1.33±0.47; 0.740.45±0.100.42±0.08; 0.63Subclavian67 (27.0)1.65±0.45; 0.910.70±0.140.70±0.13; 0.99Axillary59 (23.8)1.74±0.65; 1.000.61±0.170.57±0.13; 0.97Any artery244 (98.4)---Legend: GCA giant cell arteritis; IMT thickness of intima-media complex; * mean±SD;Conclusion:CDS of seven preselected cranial and aortic arch arteries provides a high diagnostic yield in GCA.Disclosure of Interests:Rok Jese: None declared, Ziga Rotar Consultant of: Speaker and consulting fees from Abbvie, Amgen, Biogen, Eli Lilly, Medis, MSD, Novartis, Pfizer, Roche, Sanofi., Speakers bureau: Speaker and consulting fees from Abbvie, Amgen, Biogen, Eli Lilly, Medis, MSD, Novartis, Pfizer, Roche, Sanofi., Matija Tomsic: None declared, ALOJZIJA HOCEVAR: None declared

Pax9 is required for cardiovascular development and interacts with Tbx1 in the pharyngeal endoderm to control 4th pharyngeal arch artery morphogenesis

Developmental defects affecting the heart and aortic arch arteries are a key phenotype observed in DiGeorge syndrome patients and are caused by a microdeletion on chromosome 22q11. Heterozygosity of TBX1, one of the deleted genes, is expressed throughout the pharyngeal arches and is considered a key component for the arch artery defects. Pax9 is expressed in the pharyngeal endoderm and is downregulated in Tbx1 mutant mice. We show here that Pax9 deficient mice are born with complex cardiovascular malformations affecting the outflow tract and aortic arch arteries with failure of the 3rd and 4th pharyngeal arch arteries to form correctly. Transcriptome analysis indicated that Pax9 and Tbx1 may function together, and mice double heterozygous for Tbx1/Pax9 presented with a significantly increased incidence of interrupted aortic arch when compared to Tbx1 heterozygous mice. Using a novel Pax9Cre allele we demonstrated that the site of this Tbx1-Pax9 genetic interaction is in the pharyngeal endoderm, therefore revealing that a Tbx1/Pax9-controlled signalling mechanism emanating from the pharyngeal endoderm is required for critical tissue interactions during normal morphogenesis of the pharyngeal arch artery system.Summary statementPax9 is required for outflow tract and aortic arch development, and functions together with Tbx1 in the pharyngeal endoderm for 4th arch artery formation.

The morphology of the arteries originating from the arcus aorta and the branches of these arteries in mole-rats (Spalax leucodon)

In this study, the aim was to investigate the anatomy of the aortic arch arteries in mole-rats (Spalax leucodon). Six adult mole-rats were used for this purpose. Coloured latex was injected into the left ventriculus of the hearts of all animals. The materials were carefully dissected and the arterial patterns of arteries originating from the aortic arch were examined. The brachiocephalic trunk, the left common carotid and the left subclavian arteries were detached from the aortic arch. The brachiocephalic trunk separated into the right subclavian and common carotid arteries. The branches separating from the subclavian arteries were on the right, the common branch giving the profund cervical, the internal thoracic, and the costocervical trunk, and on the left the internal thoracic and the costocervical trunk were in the common root and the profund cervical artery was independent and on both sides after giving the common branch of the superficial servical and the external thoracic artery. This continued as the axillary artery which was then separated into the subscapular and the brachial arteries. Thus, the arteries originating from the aortic arch and the branches of these arteries were found to be different from other rodents and domestic mammals.