Circulating endothelial cells as markers of endothelial dysfunction during hematopoietic stem cell transplantation for pediatric primary immunodeficiency

Neurological involvement in hematopoietic stem cell transplantation-associated thrombotic microangiopathy

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a well-recognized serious complication of hematopoietic stem cell transplantation (HSCT). The understanding of TA-TMA pathophysiology has expanded in recent years. Dysregulation of the complement system is thought to cause endothelial injury and, consequently, microvascular thrombosis and tissue damage. TA-TMA can affect multiple organs, and each organ exhibits specific features of injury. Central nervous system (CNS) manifestations of TA-TMA include posterior reversible encephalopathy syndrome, seizures, and encephalopathy. The development of neurological dysfunction is associated with a significantly lower overall survival in patients with TA-TMA. However, there are currently no established histopathological or radiological criteria for the diagnosis of CNS TMA. Patients who receive total body irradiation (TBI), calcineurin inhibitors (CNI), and severe acute and chronic graft-versus-host disease (GVHD) are at a high risk of experiencing neurological complications related to TA-TMA and should be considered for directed TA-TMA therapy. However, the incidence and clinical manifestations of TA-TMA neurotoxicity remain unclear. Studies specifically examining the involvement of CNS in TMA syndromes are limited. In this review, we discuss clinical manifestations and imaging abnormalities in patients with nervous system involvement in TA-TMA. We summarize the mechanisms underlying TA-TMA and its neurological complications, including endothelial injury, evidence of complement activation, and treatment options for TA-TMA.

Endothelial Dysfunction Syndromes after Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only therapy with a curative potential for a variety of malignant and non-malignant diseases. The major limitation of the procedure is the significant morbidity and mortality mainly associated with the development of graft versus host disease (GVHD) as well as with a series of complications related to endothelial injury, such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), transplant-associated thrombotic microangiopathy (TA-TMA), etc. Endothelial cells (ECs) are key players in the maintenance of vascular homeostasis and during allo-HSCT are confronted by multiple challenges, such as the toxicity from conditioning, the administration of calcineurin inhibitors, the immunosuppression associated infections, and the donor alloreactivity against host tissues. The early diagnosis of endothelial dysfunction syndromes is of paramount importance for the development of effective prophylactic and therapeutic strategies. There is an urgent need for the better understanding of the pathogenetic mechanisms as well as for the identification of novel biomarkers for the early diagnosis of endothelial damage. This review summarizes the current knowledge on the biology of the endothelial dysfunction syndromes after allo-HSCT, along with the respective therapeutic approaches, and discusses the strengths and weaknesses of possible biomarkers of endothelial damage and dysfunction.

Renal Carcinoma and Angiogenesis: Therapeutic Target and Biomarkers of Response in Current Therapies

Due to the aberrant hypervascularization and the high immune infiltration of renal tumours, current therapeutic regimens of renal cell carcinoma (RCC) target angiogenic or immunosuppressive pathways or both. Tumour angiogenesis plays an essential role in tumour growth and immunosuppression. Indeed, the aberrant vasculature promotes hypoxia and can also exert immunosuppressive functions. In addition, pro-angiogenic factors, including VEGF-A, have an immunosuppressive action on immune cells. Despite the progress of treatments in RCC, there are still non responders or acquired resistance. Currently, no biomarkers are used in clinical practice to guide the choice between the different available treatments. Considering the role of angiogenesis in RCC, angiogenesis-related markers are interesting candidates. They have been studied in the response to antiangiogenic drugs (AA) and show interest in predicting the response. They have been less studied in immunotherapy alone or combined with AA. In this review, we will discuss the role of angiogenesis in tumour growth and immune escape and the place of angiogenesis-targeted biomarkers to predict response to current therapies in RCC.

Circulating endothelial cells and endothelial progenitor cells as potential predictors of acute GVHD after allogeneic hematopoietic stem cell transplantation

OBJECTIVE

Acute graft-versus-host disease (aGVHD) is a major cause of treatment-related mortality after allogeneic hematopoietic stem cell transplantation. Endothelial cell damage may trigger the initiation of aGVHD.

METHODS

Endothelial damage and repair were evaluated by counting circulating endothelial cells (CECs) and endothelial progenitor cells (EPCs) in 17 allogeneic hematopoietic stem cell transplantation patients at pre-conditioning, day 0, day 7, day 14, day 30, and day 60 by multicolor flow cytometry. Von Willebrand factor activity was simultaneously measured.

RESULTS

Eight patients developed aGVHD and were compared to non-aGVHD patients. Patients' characteristics were not different, except for previous treatment courses. There was no difference in von Willebrand factor activity between the two groups. Both CEC and EPC counts were decreased on day 7 and day 14 and then increased thereafter. The CEC count on day 7 was significantly lower in the aGVHD group than in the non-aGVHD group (p = .0401). Restoration of the EPC count on day 60 was significantly suppressed in the aGVHD group (p = .0464). The CEC count on day 7 could predict aGVHD development (AUC 0.8214, p = .0372).

CONCLUSION

The present results showed that CEC count on day 7 could be a predictor of aGVHD.

Early Prediction of Cardiovascular Risk after Hematopoietic Cell Transplantation: Are We There Yet?

Cardiovascular (CV) events have emerged as a major cause of morbidity and mortality among hematopoietic cell transplantation (HCT) survivors. Accumulating evidence supports the presence of increased CV risk in HCT recipients. Most studies have focused mainly on traditional CV risk factors, such as the metabolic syndrome and hypertension. However, detection of these factors suggests the development of irreversible overt clinical atherosclerosis. Therefore, earlier prediction of CV risk is needed to prevent CV morbidity and mortality in these patients. In the field of CV research, endothelial dysfunction is considered an early event in the pathophysiology of CV risk factors, and a number of markers have been proposed for its assessment. In addition, markers of subclinical target organ damage have been introduced to implement CV risk prediction and early preventive or intensive therapeutic interventions. Furthermore, a number of CV models have been suggested aiming for optimal stratification of patients. Preliminary studies have indicated excess CV risk using these early markers in HCT recipients. However, their role in the pathophysiology and clinical practice in HCT survivors remains largely understudied. Taking into account the need for increased awareness from treating physicians in this evolving setting, we conducted a state-of-the-art review aiming to summarize current knowledge on endothelial dysfunction, subclinical target organ damage, and CV risk prediction in HCT survivors.

Circulating endothelial cell count: a reliable marker of endothelial damage in patients undergoing hematopoietic stem cell transplantation

The physio-pathologic interrelationships between endothelium and GvHD have been better elucidated and have led to definition of the entity 'endothelial GvHD' as an essential early phase prior to the clinical presentation of acute GvHD. Using the CellSearch system, we analyzed circulating endothelial cells (CEC) in 90 allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients at the following time-points: T1 (pre-conditioning), T2 (pre-transplant), T3 (engraftment), T4 (onset of GvHD) and T5 (1 week after steroid treatment). Although CEC changes in allo-HSCT represent a dynamic phenomenon influenced by many variables (that is, conditioning, immunosuppressive treatments, engraftment syndrome and infections), we showed that CEC peaks were constantly seen at onset of acute GvHD and invariably returned to pre-transplant values after treatment response. Since we showed that CEC changes during allo-HSCT has rapid kinetics that may be easily missed if blood samples are drawn at pre-fixed time-points, we rather suggest an 'on demand' evaluation of CEC counts right at onset of GvHD clinical symptoms to possibly help differentiate GvHD from other non-endothelial complications. We confirm that CEC changes are a suitable biomarker to monitor endothelial damage in patients undergoing allo-transplantation and hold the potential to become a useful tool to support GvHD diagnosis (ClinicalTrials.gov NCT02064972).

Advances and highlights in mechanisms of allergic disease in 2015

This review highlights some of the advances in mechanisms of allergic disease, particularly anaphylaxis, including food allergy, drug hypersensitivity, atopic dermatitis (AD), allergic conjunctivitis, and airway diseases. During the last year, a mechanistic advance in food allergy was achieved by focusing on mechanisms of allergen sensitization. Novel biomarkers and treatment for mastocytosis were presented in several studies. Novel therapeutic approaches in the treatment of atopic dermatitis and psoriasis showed that promising supplementation of the infant's diet in the first year of life with immunoactive prebiotics might have a preventive role against early development of AD and that therapeutic approaches to treat AD in children might be best directed to the correction of a TH2/TH1 imbalance. Several studies were published emphasizing the role of the epithelial barrier in patients with allergic diseases. An impaired skin barrier as a cause for sensitization to food allergens in children and its relationship to filaggrin mutations has been an important development. Numerous studies presented new approaches for improvement of epithelial barrier function and novel biologicals used in the treatment of inflammatory skin and eosinophilic diseases. In addition, novel transcription factors and signaling molecules that can develop as new possible therapeutic targets have been reported.

Advances in basic and clinical immunology in 2014

Genetic identification of immunodeficiency syndromes has become more efficient with the availability of whole-exome sequencing, expediting the identification of relevant genes and complementing traditional linkage analysis and homozygosity mapping. New genes defects causing immunodeficiency include phophoglucomutase 3 (PGM3), cytidine 5' triphosphate synthase 1 (CTPS1), nuclear factor κB-inducing kinase (NIK), cytotoxic T lymphocyte-associated antigen 4 (CTLA4), B-cell chronic lymphocytic leukemia/lymphoma 10 (BCL10), phosphoinositide-3 kinase regulatory subunit 1 (PIK3R1), IL21, and Jagunal homolog 1 (JAGN1). New case reports expanded the clinical spectrum of gene defects. For example, a specific recombination-activating gene 1 variant protein with partial recombinant activity might produce Omenn syndrome or a common variable immunodeficiency phenotype. Central and peripheral B-cell tolerance was investigated in patients with several primary immunodeficiencies, including common variable immunodeficiency and Wiskott-Aldrich syndrome, to explain the occurrence of autoimmunity and inflammatory disorders. The role of IL-12 and IL-15 in the enhancement of natural killer cell activity was reported. Newborn screening for T-cell deficiency is being implemented in more states and is achieving its goal of defining the true incidence of severe combined immunodeficiency and providing early treatment that offers the highest survival for these patients. Definitive treatment of severe immunodeficiency with both hematopoietic stem cell transplantation and gene therapy was reported to be successful, with increasing definition of conditions needed for optimal outcomes. Progress in HIV infection is directed toward the development of an effective vaccine and the eradication of hidden latent virus reservoirs.