Impact of heterozygous ALK1 mutations on the transcriptomic response to BMP9 and BMP10 in endothelial cells from hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension donors

Heterozygous activin receptor-like kinase 1 (ALK1) mutations are associated with two vascular diseases: hereditary hemorrhagic telangiectasia (HHT) and more rarely pulmonary arterial hypertension (PAH). Here, we aimed to understand the impact of ALK1 mutations on BMP9 and BMP10 transcriptomic responses in endothelial cells. Endothelial colony-forming cells (ECFCs) and microvascular endothelial cells (HMVECs) carrying loss of function ALK1 mutations were isolated from newborn HHT and adult PAH donors, respectively. RNA-sequencing was performed on each type of cells compared to controls following an 18 h stimulation with BMP9 or BMP10. In control ECFCs, BMP9 and BMP10 stimulations induced similar transcriptomic responses with around 800 differentially expressed genes (DEGs). ALK1-mutated ECFCs unexpectedly revealed highly similar transcriptomic profiles to controls, both at the baseline and upon stimulation, and normal activation of Smad1/5 that could not be explained by a compensation in cell-surface ALK1 level. Conversely, PAH HMVECs revealed strong transcriptional dysregulations compared to controls with > 1200 DEGs at the baseline. Consequently, because our study involved two variables, ALK1 genotype and BMP stimulation, we performed two-factor differential expression analysis and identified 44 BMP9-dysregulated genes in mutated HMVECs, but none in ECFCs. Yet, the impaired regulation of at least one hit, namely lunatic fringe (LFNG), was validated by RT-qPCR in three different ALK1-mutated endothelial models. In conclusion, ALK1 heterozygosity only modified the BMP9/BMP10 regulation of few genes, including LFNG involved in NOTCH signaling. Future studies will uncover whether dysregulations in such hits are enough to promote HHT/PAH pathogenesis, making them potential therapeutic targets, or if second hits are necessary.

Concomitant association of giant cell arteritis and malignancy: a multicenter retrospective case-control study

INTRODUCTION

Some studies suggest that there is an increased risk of malignancies in giant cell arteritis (GCA). We aimed to describe the clinical characteristics and outcomes of GCA patients with concomitant malignancy and compare them to a GCA control group.

METHOD

Patients with a diagnosis of GCA and malignancy and with a maximal delay of 12 months between both diagnoses were retrospectively included in this study and compared to a control group of age-matched (3:1) patients from a multicenter cohort of GCA patients.

RESULTS

Forty-nine observations were collected (median age 76 years). Malignancies comprised 33 (67%) solid neoplasms and 16 (33%) clonal hematologic disorders. No over-representation of a particular type of malignancy was observed. Diagnosis of GCA and malignancy was synchronous in 7 (14%) patients, while malignancy succeeded GCA in 29 (59%) patients. Malignancy was fortuitously diagnosed based on abnormalities observed in laboratory tests in 26 patients, based on imaging in 14 patients, and based on symptoms or clinical examination in the nine remaining patients. Two patients had a concomitant relapse of both conditions. When compared to the control group, patients with concomitant GCA and malignancy were more frequently male (p < 0.001), with an altered general state (p < 0.001), and polymyalgia rheumatica (p < 0.01).

CONCLUSIONS

This study does not indicate an over-representation of any particular type of malignancy in GCA patients. Initial follow-up dictated by vasculitis may have led to an early identification of malignancy. Nevertheless, GCA male patients with an altered general state and polymyalgia rheumatica might more frequently show concomitant malignancies.

Direct oral anticoagulants: an alternative treatment for thrombotic antiphospholipid syndrome?

Background

Direct oral anticoagulants (DOACs) demonstrate a lower risk–benefit ratio than vitamin K antagonists (VKAs) for secondary thromboprophylaxis of thrombotic events. But there are no data on the efficacy of DOACs for the prevention of thrombotic recurrence in patients with antiphospholipid syndrome (APS). In this study, we evaluated the efficacy of DOACs to prevent recurrences of thrombotic events in patients with APS.

Methods

This was a single-center pilot, using a multi-step Fleming design. If seven or fewer patients presented treatment failure with rivaroxaban, the study could conclude efficacy.

Results

A total of 23 patients were included. APS involved the veins only ( n = 19), arteries only ( n = 2) or both ( n = 1) and 1 patient exhibited catastrophic antiphospholipid syndrome (CAPS). Overall, two patients were positive for lupus anticoagulant, anti-beta-2 glycoprotein I antibodies and anticardiolipid antibodies (triple positivity). The mean duration of follow up was 35.6 (range, 29–40) months. A total of six treatment failures were reported: one patient, with triple positivity, developed bilateral distal pulmonary embolism (PE) after 20 months of treatment with rivaroxaban, two patients refused to take rivaroxaban, the treatment was stopped in three other patients: two with adverse effects and one with chronic iron-deficiency anemia.

Conclusions

Rivaroxaban may represent an alternative for secondary thromboprophylaxis for thrombo-embolism in patients with APS, in particular, those with poor international normalized ratio (INR) control and those who are not at the highest risk of recurrent thrombosis, such as those with triple positivity.