Distinct CD11b-monocyte subsets accelerate endothelial cell recovery after acute and chronic endothelial cell damage

Background

Endothelial cell recovery requires replenishment of primary cells from the endothelial lineage. However, recent evidence suggests that cells of the innate immune system enhance endothelial regeneration.

Methods and results

Focusing on mature CD11b⁺-monocytes, we analyzed the fate and the effect of transfused CD11b⁺-monocytes after endothelial injury in vivo. CD11b-diphtheria-toxin-receptor-mice – a mouse model in which administration of diphtheria toxin selectively eliminates endogenous monocytes and macrophages – were treated with WT-derived CD11b⁺-monocytes from age-matched mice. CD11b⁺-monocytes improved endothelium-dependent vasoreactivity after 7 days while transfusion of WT-derived CD11b⁻-cells had no beneficial effect on endothelial function. In ApoE^−/−-CD11b-DTR-mice with a hypercholesterolemia-induced chronic endothelial injury transfusion of WT-derived CD11b⁺-monocytes stimulated by interferon-γ (IFNγ) decreased endothelial function, whereas interleukin-4-stimulated (IL4) monocytes had no detectable effect on vascular function. Bioluminescent imaging revealed restriction of transfused CD11b⁺-monocytes to the endothelial injury site in CD11b-DTR-mice depleted of endogenous monocytes. In vitro co-culture experiments revealed significantly enhanced regeneration properties of human endothelial outgrowth cells (EOCs) when cultured with preconditioned-media (PCM) or monocytes of IL4-stimulated-subsets compared to the effects of IFNγ-stimulated monocytes.

Conclusion

CD11b⁺-monocytes play an important role in endothelial cell recovery after endothelial injury by homing to the site of vascular injury, enhancing reendothelialization and improving endothelial function. In vitro experiments suggest that IL4-stimulated monocytes enhance EOC regeneration properties most likely by paracrine induction of proliferation and cellular promotion of differentiation. These results underline novel insights in the biology of endothelial regeneration and provide additional information for the treatment of vascular dysfunction.     

Deprescribing: Future directions for research

A World Café workshop was held at the Bruyère Evidence-Based Deprescribing Guidelines Symposium in March 2018 with 30 participants (researchers, clinicians, policy makers, stakeholders). This workshop explored priorities for future work in the field of deprescribing and deprescribing guidelines through group discussion. The discussions were guided by the following questions: (1) What are deprescribing research priorities (to inform guideline development), (2) What outcome measures are important for developing deprescribing guidelines, and (3) How do we evaluate the implementation and effectiveness of deprescribing guidelines? Discussion from all 3 questions identified 6 main priority areas: (1) conducting high-quality and long-term clinical trials that measure patient-important outcomes, (2) focusing on patient involvement and perspectives, (3) investigating the pharmacoeconomics of deprescribing interventions, (4) understanding deprescribing interventions in different populations, (5) generating evidence on clinical management during deprescribing (e.g. managing adverse drug withdrawal effects, subsequent re-prescribing), and (6) implementing interventions in clinical practice. These topics represent what a group of experienced researchers, clinicians, and stakeholders in the field collectively felt was important to consider for design and implementation of future deprescribing studies. The aim is for these findings to stimulate future discussions and be considered by granting agencies, policy makers, deprescribing research networks, and individual researchers planning future deprescribing studies.     

Cerebral vein thrombosis in patients with Philadelphia‐negative myeloproliferative neoplasms An European Leukemia Net study

To investigate the characteristics and clinical course of cerebral vein thrombosis (CVT) in patients with myeloproliferative neoplasms (MPN) we compared 48 patients with MPN and CVT (group MPN‐CVT) to 87 with MPN and other venous thrombosis (group MPN‐VT) and 178 with MPN and no thrombosis (group MPN‐NoT) matched by sex, age at diagnosis of MPN (±5 years) and type of MPN. The study population was identified among 5,500 patients with MPN, from January 1982 to June 2013. Thrombophilia abnormalities were significantly more prevalent in the MPN‐CVT and MPN‐VT than in MPN‐NoT group (P = 0.015), as well as the JAK2 V617F mutation in patients with essential thrombocythemia (P = 0.059). Compared to MPN‐VT, MPN‐CVT patients had a higher rate of recurrent thrombosis (42% vs. 25%, P = 0.049) despite a shorter median follow‐up period (6.1 vs. 10.3 years, P = 0.019), a higher long‐term antithrombotic (94% vs. 84%, P = 0.099) and a similar cytoreductive treatment (79% vs. 70%, P = 0.311). The incidence of recurrent thrombosis was double in MPN‐CVT than in MPN‐VT group (8.8% and 4.2% patient‐years, P = 0.022), and CVT and unprovoked event were the only predictive variables in a multivariate model including also sex, blood count, thrombophilia, cytoreductive, and antithrombotic treatment (HR 1.97, 95%CI 1.05–3.72 and 2.09, 1.09–4.00, respectively). Am. J. Hematol. 89:E200–E205, 2014. © 2014 Wiley Periodicals, Inc.     

Masked polycythemia Vera (mPV): Results of an international study

We examined the baseline features and clinical outcomes of 140 patients presenting with JAK2V617F positivity and a bone marrow morphology conforming with WHO criteria of polycythemia vera (PV), but a hemoglobin level of <18.5 g/dL in males (range 16.0–18.4) and <16.5 g/dL in females (range 15.0–16.4). This cohort operationally referred to as masked PV (mPV) was compared with 257 patients with overt PV and displayed male predominance, a more frequent history of arterial thrombosis and thrombocytosis. Incidence of thrombosis was similar between the two groups but mPV displayed significantly higher rates of progression to myelofibrosis and acute leukemia and inferior survival. In multivariable analysis mPV diagnosis was an independent predictor of poor survival along with age >65 years and leukocyte count >10 × 10⁹/L. Our data suggest that mPV is a heterogeneous myeloproliferative neoplasia and not necessarily an early/ pre‐polycythemic form of classical PV that at onset in a small fraction of patients clinically may mimic essential thrombocythemia. On the other hand, the majority mPV may have a longer prodrome of undiagnosed PV or a disease biology akin to primary myelofibrosis‐post PV myelofibrosis that could explain the worsening of outcome in comparison to overt/classical manifestations. Am. J. Hematol. 89:52–54, 2014. © 2013 Wiley Periodicals, Inc.     

IGH@ translocations co-exist with other primary rearrangements in B-cell precursor acute lymphoblastic leukemia

Primary established genetic abnormalities in B-cell precursor acute lymphoblastic leukemia include high hyperdiploidy (51–65 chromosomes), the translocations t(12;21)(p13;q22)/ETV6-RUNX1 fusion and t(9;22)(q34;q11)/BCR-ABL1 fusion, MLL rearrangements and intrachromosomal amplification of chromosome 21. These rearrangements are of prognostic and therapeutic relevance and are usually mutually exclusive. We identified 28 patients at diagnosis with both a primary genetic rearrangement and an immunoglobulin heavy chain locus translocation using chromosomal analysis and fluorescence in situ hybridization. Among these patients, the immunoglobulin heavy chain locus translocation partner gene was identified in six (CRLF2, CEBPA, CEBPB, TRA/D@, IGF2BP1 and IGK@). Clonal architecture was investigated in 17 patients using multiple color interphase fluorescence in situ hybridization analysis, which showed that the translocation was acquired as a secondary abnormality in ten patients, in four patients the etiology was undetermined and in three patients it was observed in a separate clone from the primary chromosomal rearrangement. These findings demonstrate the co-existence of immunoglobulin heavy chain locus translocations with other primary chromosomal rearrangements either in the same or separate clones, which may have prognostic significance in B-cell precursor acute lymphoblastic leukemia. Clinical trials: UKALLXII: Study ID n. ISRCTN77346223 and ALL2003: Study ID n. ISRCTN07355119