Identification of novel biomarkers in chronic immune thrombocytopenia (ITP) by microarray-based serum protein profiling

Interleukin-37, vascular endothelial growth factor A, and transforming growth factor-β1: promising biomarkers in primary immune thrombocytopenia

BACKGROUND

Immune thrombocytopenic purpura (ITP) is an acquired autoimmune hematologic disorder with heterogeneous bleeding manifestations. Many biomarkers such as interleukin-37 (IL-37), vascular endothelial growth factor A (VEGFA), and transforming growth factor-β1 (TGFß1) have a role in immunity, inflammation, and megakaryopoiesis.

METHODS

In the present study, immunoassay of interleukin-37 as well as the gene expression of vascular endothelial growth factor A and transforming growth factor-β1 were done in 60 primary ITP patients, 60 thrombocytopenia patients, and 60 healthy volunteers.

RESULTS

Increased IL-37 level and down regulation of VEGFA and TGFß1gene expression were detected in primary ITP patients when compared with other groups. A negative correlation was observed between IL-37 and platelet count. However, a positive correlation was observed between VEGFA and TGFß1 levels and platelet count.

CONCLUSION

Current results suggested that interleukin-37, vascular endothelial growth factor A, and transforming growth factor-β may be promising indicators in the diagnosis of ITP and detection of disease severity with inexpensive and cost-effectiveness compared to the benefits.

New developments in the diagnosis of primary immune thrombocytopenia

Immune thrombocytopenia is an acquired autoimmune disorder, which can affect both adults and children, characterized by lower than normal platelet counts (below 100 × 109/l). Thrombocytopenia may result in an increased risk of bleeding and puts patients at risk for serious complications. In the last decade, the multifactorial pathogenesis of ITP has become apparent, leading to greater understanding that different immune-mediated mechanisms could be involved in each patient, explaining the variable clinical presentation and response to therapies. The management of ITP patients has changed considerably in these past 10 years, but diagnosis of the disease has changed little, and remains clinical and possible only with the exclusion of other causes of thrombocytopenia. Although the search for such a test continues, to date, there is no reliable biomarker or gold-standard diagnostic test, which contributes to the high rate of misdiagnosis of the disease. This review presents the current limitations in the identification of the molecular disease underlying this disorder.

Acquired Glanzmann thrombasthenia: From antibodies to anti-platelet drugs

In contrast to the inherited platelet disorder given by mutations in the ITGA2B and ITGB3 genes, mucocutaneous bleeding from a spontaneous inhibition of normally expressed αIIbβ3 characterizes acquired Glanzmann thrombasthenia (GT). Classically, it is associated with autoantibodies or paraproteins that block platelet aggregation without causing a fall in platelet count. However, inhibitory antibodies to αIIbβ3 are widely associated with primary immune thrombocytopenia (ITP), occur in secondary ITP associated with leukemia and related disorders, solid cancers and myeloma, other autoimmune diseases, following organ transplantation while cytoplasmic dysregulation of αIIbβ3 function features in myeloproliferative and myelodysplastic syndromes. Antibodies to αIIbβ3 occur during viral and bacterial infections, while drug-dependent antibodies reacting with αIIbβ3 are a special case. Direct induction of acquired GT is a feature of therapies that block platelets in coronary artery disease. This review looks at these conditions, emphasizing molecular mechanisms, therapy, patient management and future directions for research.

Is Autoimmune Thrombocytopenia Itself the Primary Disease in the Presence of Second Diseases Data from a Long-Term Observation

BACKGROUND

Dependent on the absence or presence of associated diseases, autoimmune thrombocytopenia (ITP) can be classified as primary or secondary form. The manifestation of the associated diseases is not temporally defined and may occur during observation. Thus the question which disease is the primary one remains unanswered.

METHODS

All 386 patients included in this study were treated by a single primary physician between 1996 and 2015 at the Charité Berlin and met current ITP criteria. Medical records and investigations were reviewed to assess diseases associated with ITP.

RESULTS

Initially, the vast majority of patients presented with primary ITP (isolated disease). Based on our findings, ITP was found to be associated with other abnormalities in most cases. These abnormalities included: positive direct antiglobulin test in 49 of 386 tested patients (13%), affections of the thyroid gland in 41 of 386 tested patients (11%), infections in 30 (8%), solid malignancies in 20 (5%) and hematological malignancies in 10 patients (3%), as well as many other miscellaneous diseases. Moreover, of 160 patients who did not receive prior intravenous immunoglobulin treatment, 40 (25%) showed antibody deficiency.

CONCLUSION

In conclusion, the incidence of 'true' ITP as a primary disease is less common than has yet been suggested. Additionally, there is evidence that ITP itself predispose affected subjects toward development of other diseases.

Secretome profiling of apheresis platelet supernatants during routine storage via antibody-based microarray

Platelet storage lesions (PSLs) occur during platelet concentrate (PC) storage. Adverse transfusion reactions (ATRs) have been demonstrated to be more frequent in older PCs and removal of the supernatant prior to transfusion reduces their occurrence. Proteomic profiling of PC supernatants was thus performed to identify proteins associated with PSLs and ATRs. Twenty-four PCs were investigated daily from day 0 to day 9 for platelet pre-activation (PPA), platelet-derived extracellular vesicles (PEVs), and platelet function. Using antibody microarrays, 673 extracellular proteins were analysed in PC supernatants on days 0, 3, 5, 7, and 9. During 5days of storage, PPA and PEVs continuously increased (P<0.0001). Platelet function was observed to remain stable within the first 5days (P=0.1751) and decreased thereafter. Comparison of all time points to day 0 revealed the identification of 136 proteins that were significantly changed in abundance during storage, of which 72 were expressed by platelets. Network analysis identified these proteins to be predominantly associated with exosomes (P=4.61×10^-8, n=45 genes) and two clusters with distinct functions were found with one being associated with haemostasis and the other with RNA binding. These findings may provide an explanation for ATRs.

SIGNIFICANCE

Changes in platelet concentrate (PC) supernatants during storage have been so far only poorly addressed and high abundant proteins burden the identification of quantitative changes in the secretome. We applied a high-throughput antibody microarray allowing for the sensitive quantification of 673 extracellular factors. PCs account for the highest number of adverse transfusion reactions (ATRs). ATRs have been demonstrated to be more frequent in older PCs and removal of the supernatant prior to transfusion reduces their occurrence. Comprehensive interpretation of the changing proteins in the secretome during platelet storage under blood banking conditions may help to identify mechanisms leading to the occurrence of adverse transfusion reactions.

Increased RUNX1 expression in patients with immune thrombocytopenia

Immune thrombocytopenia (ITP) is a heterogeneous autoimmune disease, characterized by dysregulation of cellular immunity. Th17 and associated IL-17 were involved in the pathogenesis of ITP. Runt-related transcription factor 1 (RUNX1), a member of the runt domain-containing family of transcription factors, is required for Th17 differentiation. Whether RUNX1 was involved in the pathogenesis of ITP remains poorly understood. In this study, 30 active ITP patients, 20 ITP in remission and 20 age and gender matched healthy controls were included. Peripheral blood mononuclear cells (PBMCs) were isolated to measure mRNA level of RUNX1 and retinoic acid receptor-related orphan receptor-γt (RORγt) by quantitative real-time PCR and Th17 cells by flow cytometry. Meanwhile, plasma was extracted for measurement of IL-17 level by ELISA. Our results showed a significantly higher expression of RUNX1, RORγt, Th17 cells and plasma level of IL-17 in active ITP patients than that in healthy controls. No differences of expression of RUNX1, RORγt and Th17 cells were observed between remission patients and controls. Furthermore, a significantly positive correlation of RUNX1 with RORγt was found in active ITP patients. In conclusion, RUNX1 was associated with the pathogenesis of ITP possibly through regulation of Th17 cell differentiation and therapeutically targeting it might be a novel approach in ITP treatment.