Defective regulatory B-cell compartment in patients with immune thrombocytopenia

Immune thrombocytopenia: Pathophysiology and impacts of Romiplostim treatment

Immune thrombocytopenia (ITP) is an autoimmune bleeding disease caused by immune-mediated platelet destruction and decreased platelet production. ITP is characterized by an isolated thrombocytopenia (<100 × 109/L) and increased risk of bleeding. The disease has a complex pathophysiology wherein immune tolerance breakdown leads to platelet and megakaryocyte destruction. Therapeutics such as corticosteroids, intravenous immunoglobulins (IVIg), rituximab, and thrombopoietin receptor agonists (TPO-RAs) aim to increase platelet counts to prevent hemorrhage and increase quality of life. TPO-RAs act via stimulation of TPO receptors on megakaryocytes to directly stimulate platelet production. Romiplostim is a TPO-RA that has become a mainstay in the treatment of ITP. Treatment significantly increases megakaryocyte maturation and growth leading to improved platelet production and it has recently been shown to have additional immunomodulatory effects in treated patients. This review will highlight the complex pathophysiology of ITP and discuss the usage of Romiplostim in ITP and its ability to potentially immunomodulate autoimmunity.

Immune thrombocytopenia (ITP) - could it be part of autoimmune/inflammatory syndrome induced by adjuvants (ASIA)?

Immune thrombocytopenia (ITP) is a complex autoimmune disorder characterized by thrombocytopenia and an increased bleeding risk, arising from autoantibody-mediated platelet destruction and impaired megakaryocyte function. The pathogenesis of ITP involves a multifaceted interplay of genetic predispositions, immune dysregulation, and environmental triggers, though the precise mechanisms remain uncertain. Several infectious agents, mostly viruses, have been implicated in both acute and chronic ITP through mechanisms such as molecular mimicry, direct bone marrow suppression, and immune dysregulation. Vaccinations, particularly those containing adjuvants like aluminum and those capable of inducing molecular mimicry, have also been associated with ITP, either as a new onset or as a relapse in preexisting cases. The role of drugs, particularly quinine, quinidine and certain antibiotics, in inducing ITP through various immunological pathways further illustrates the diverse etiologies of this condition. The multiple triggers of the disease raise the question of whether ITP may be classified as an autoimmune/inflammatory syndrome induced by adjuvants (ASIA). This condition encompasses a range of autoimmune and inflammatory symptoms triggered by adjuvants, such as silicones, polypropylene meshes, metal implants, and mineral oils present in various medical materials and medications. Similar to that observed in some cases of ITP, adjuvants can trigger autoimmune or autoinflammatory responses via molecular mimicry, epitope spreading, and polyclonal activation. This narrative review explores the underlying environmental factors related to ITP and examines ITP triggers that could potentially support an association between ITP and ASIA syndrome.

High dimensional proteomic mapping of bone marrow immune characteristics in immune thrombocytopenia

To investigate the role of co-stimulatory and co-inhibitory molecules on immune tolerance in immune thrombocytopenia (ITP), this study mapped the immune cell heterogeneity in the bone marrow of ITP at the single-cell level using Cytometry by Time of Flight (CyTOF). Thirty-six patients with ITP and nine healthy volunteers were enrolled in the study. As soluble immunomodulatory molecules, more sCD25 and sGalectin-9 were detected in ITP patients. On the cell surface, co-stimulatory molecules like ICOS and HVEM were observed to be upregulated in mainly central memory and effector T cells. In contrast, co-inhibitory molecules such as CTLA-4 were significantly reduced in Th1 and Th17 cell subsets. Taking a platelet count of 30×109 L-1 as the cutoff value, ITP patients with high and low platelet counts showed different T cell immune profiles. Antigen-presenting cells such as monocytes and B cells may regulate the activation of T cells through CTLA-4/CD86 and HVEM/BTLA interactions, respectively, and participate in the pathogenesis of ITP. In conclusion, the proteomic and soluble molecular profiles brought insight into the interaction and modulation of immune cells in the bone marrow of ITP. They may offer novel targets to develop personalized immunotherapies.

Platelet-derived TGF-β1 induces functional reprogramming of myeloid-derived suppressor cells in immune thrombocytopenia

ABSTRACT

Platelet α-granules are rich in transforming growth factor β1 (TGF-β1), which is associated with myeloid-derived suppressor cell (MDSC) biology. Responders to thrombopoietin receptor agonists (TPO-RAs) revealed a parallel increase in the number of both platelets and MDSCs. Here, anti-CD61 immune-sensitized splenocytes were transferred into severe combined immunodeficient mice to establish an active murine model of immune thrombocytopenia (ITP). Subsequently, we demonstrated that TPO-RAs augmented the inhibitory activities of MDSCs by arresting plasma cells differentiation, reducing Fas ligand expression on cytotoxic T cells, and rebalancing T-cell subsets. Mechanistically, transcriptome analysis confirmed the participation of TGF-β/Smad pathways in TPO-RA-corrected MDSCs, which was offset by Smad2/3 knockdown. In platelet TGF-β1-deficient mice, TPO-RA-induced amplification and enhanced suppressive capacity of MDSCs was waived. Furthermore, our retrospective data revealed that patients with ITP achieving complete platelet response showed superior long-term outcomes compared with those who only reach partial response. In conclusion, we demonstrate that platelet TGF-β1 induces the expansion and functional reprogramming of MDSCs via the TGF-β/Smad pathway. These data indicate that platelet recovery not only serves as an end point of treatment response but also paves the way for immune homeostasis in immune-mediated thrombocytopenia.

[Pathophysiology and Diagnostics of Immune Thrombocytopenia]

Immune thrombocytopenia (ITP) is due to autoantibodies against platelet surface antigens. ITP is considered as either primary, with no clear etiology, or as secondary ITP (drug-induced; underlying diseases). Autoantibodies lead both to loss of platelets in the spleen and/or liver but simultaneously reduce their production. Contrary to other disorders with thrombocytopenia, ITP has reduced levels of thrombopoetin. ITP remains a diagnosis of exclusion. A single defining laboratory test does not exist. Glycoprotein-specific antibodies can be detected in only about 50% of cases. Ruling out EDTA-induced pseudo thrombocytopenia is of particular relevance. Secondary causes of thrombocytopenia should be excluded through medical history (especially medication history), physical examination and possibly bone-marrow puncture.

Trimethylamine-N-oxide (TMAO) and basic fibroblast growth factor (bFGF) are possibly involved in corticosteroid resistance in adult patients with immune thrombocytopenia

PURPOSE

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by accelerated platelet clearance. Gut dysbiosis was associated with its pathogenesis, but the underlying mechanisms have not been fully elucidated. Patients with ITP exhibit varying degrees of responsiveness to corticosteroid treatment. Therefore, prognostic indexes for corticosteroid responsiveness in ITP could offer valuable guidance for clinical practices.

METHODS

The present study examined the signature of six types of gut-microbiota metabolites and forty-eight types of cytokines, chemokines, and growth factors and their clinical significance in patients with ITP.

RESULTS

Both patients with good and poor corticosteroid responsiveness exhibited significantly elevated/suppressed secretion of twenty-two cyto(chemo)kins/growth factors in comparison to healthy controls. Additionally, patients with ITP demonstrated a significant decrease in plasma levels of trimethylamine-N-oxide (TMAO), which was found to be negatively correlated to circulating platelet counts, and positively correlated with Interleukin (IL)-1β and IL-18. Notably, patients who exhibited poor response to corticosteroid treatment displayed elevated levels of TMAO and basic fibroblast growth factor (bFGF) in comparison to responders. Additionally, we found that the amalgamation of TMAO, bFGF and interleukin (IL)-13 could serve as a valuable prognostic tool for predicting CS responsiveness.

CONCLUSION

Patients with ITP were characterized overall by an imbalanced secretion of cyto(cheo)kins/growth factors and inadequate levels of TMAO. The varying degrees of responsiveness to corticosteroid treatment can be attributed to different profiles of basic FGF and TMAO that might be related to overburdened oxidative stress and inflammasome overactivation, and ultimately mediate corticosteroid resistance.

Diffuse large B‑cell lymphoma and monoclonal gammopathy secondary to immune thrombocytopenic purpura: A case report

The present study reports the case of a patient with diffuse large B-cell lymphoma (DLBCL) and monoclonal gammopathy (MG) secondary to immune thrombocytopenia purpura (ITP). The clinical diagnoses and investigations of this case are reported. To the best of our knowledge, this is the first study to report DLBCL and MG secondary to ITP. The patient presented with a rare constellation of diseases, which made the diagnosis and treatment difficult for the physicians. The patient was followed up for 10 years using the morphological examination of bone marrow cells after chemotherapy, and currently continues with follow-up examinations. Treatments and prognoses for ITP, DLBCL and MG are common. However, treatments and prognoses are unclear for patients with all three conditions. The different clinical manifestations and disease processes of DLBCL and MG secondary to ITP cause difficulties for physicians in terms of treatment and prognosis. The present case report describes the comprehensive evaluation, diagnosis and treatment of a patient with DLBCL and MG secondary to, and concurrent with, ITP.

Emerging data on thrombopoietin receptor agonists for management of chemotherapy-induced thrombocytopenia

INTRODUCTION

Chemotherapy-induced thrombocytopenia (CIT) is a common complication of cancer treatment, frequently leading to reduced relative dose intensity, and is associated with reduced survival. Given the lack of FDA-approved therapies for CIT, thrombopoietin receptor agonists (TPO-RAs) have received significant attention for treatment and prevention of CIT.

AREAS COVERED

This review will summarize the development of prior agents for treatment of CIT, discuss the existing literature investigating the use of TPO-RAs in CIT primarily in patients with solid tumor malignancies, and offer insights on the future direction of TPO-RAs and other therapeutics for CIT.

EXPERT OPINION

In alignment with NCCN guidelines, we recommend that patients with CIT participate in a clinical trial for consideration of TPO-RA treatment or consider off-label use of romiplostim when participation in clinical trials is not possible. The literature to date supports the use of TPO-RAs for treatment of persistent CIT. Further data is needed to describe the long-term efficacy, safety, and prescribing practices of TPO-RAs in a diverse patient population with a variety of tumor types and chemotherapy regimens in addition to exploring the underlying biology of CIT.

In chronic lymphocytic leukemia, activation of the thrombopoietin receptor promotes T-cell inhibitory properties, contributing to immunosuppression

In chronic lymphocytic leukemia (CLL), the immune system is skewed towards a suppressive milieu. Levels of thrombopoietin (TPO), promoting cellular immune regulatory activity in immune thrombocytopenic purpura, were shown to be elevated in CLL patients. This study explored TPO as a potential immunomodulator, supporting CLL progression. We evaluated CLL cell-induced expression of TPO receptor (TPO-R) on T-cells and effects of its activation on T-cell responses. CLL cell involvement in TPO generation was also assessed. Baseline TPO-R expression on CD4 + T-cells was found to be higher in CLL patients than in healthy controls (HC). Exposure of HC-T-cells to B-cells, especially to CLL-B-cells stimulated with B-cell activating molecules, resulted in enhanced TPO-R expression on T-cells. CLL-T-cell stimulation with TPO reduced their proliferation and expanded the regulatory T-cell (Treg) population. At baseline, phosphorylation of STAT5, known to impact the Treg phenotype, was elevated in CLL-T-cells relative to those of HC. Exposure to TPO further enhanced STAT5 phosphorylation in CLL-T-cells, possibly driving the observed Treg expansion. The CLL immune milieu is involved in promotion of inhibitory features in T-cells through increased TPO-R levels and TPO-induced intracellular signaling. TPO and its signaling pathway could potentially support immunosuppression in CLL, and may emerge as novel therapeutic targets.

Autoimmune pathogenesis, immunosuppressive therapy and pharmacological mechanism in aplastic anemia

Acquired aplastic anemia (AA) is an autoimmune disease of bone marrow failure mediated by abnormally activated T cells, manifested by severe depletion of hematopoietic stem and progenitor cells (HSPCs) and peripheral blood cells. Due to the limitation of donors for hematopoietic stem cell transplantation, immunosuppressive therapy (IST) is currently an effective first-line treatment. However, a significant proportion of AA patients remain ineligible for IST, relapse, and develop other hematologic malignancies, such as acute myeloid leukemia after IST. Therefore, it is important to elucidate the pathogenic mechanisms of AA and to identify treatable molecular targets, which is an attractive way to improve these outcomes. In this review, we summarize the immune-related pathogenesis of AA, pharmacological targets, and clinical effects of the current mainstream immunosuppressive agents. It provides new insight into the combination of immunosuppressive drugs with multiple targets, as well as the discovery of new druggable targets based on current intervention pathways.

Interactions between Platelets and Tumor Microenvironment Components in Ovarian Cancer and Their Implications for Treatment and Clinical Outcomes

Platelets, the primary operatives of hemostasis that contribute to blood coagulation and wound healing after blood vessel injury, are also involved in pathological conditions, including cancer. Malignancy-associated thrombosis is common in ovarian cancer patients and is associated with poor clinical outcomes. Platelets extravasate into the tumor microenvironment in ovarian cancer and interact with cancer cells and non-cancerous elements. Ovarian cancer cells also activate platelets. The communication between activated platelets, cancer cells, and the tumor microenvironment is via various platelet membrane proteins or mediators released through degranulation or the secretion of microvesicles from platelets. These interactions trigger signaling cascades in tumors that promote ovarian cancer progression, metastasis, and neoangiogenesis. This review discusses how interactions between platelets, cancer cells, cancer stem cells, stromal cells, and the extracellular matrix in the tumor microenvironment influence ovarian cancer progression. It also presents novel potential therapeutic approaches toward this gynecological cancer.

How we treat primary immune thrombocytopenia in adults

Primary immune thrombocytopenia (ITP) is an immune-mediated bleeding disorder characterized by decreased platelet counts and an increased risk of bleeding. Multiple humoral and cellular immune abnormalities result in accelerated platelet destruction and suppressed platelet production in ITP. The diagnosis remains a clinical exclusion of other causes of thrombocytopenia. Treatment is not required except for patients with active bleeding, severe thrombocytopenia, or cases in need of invasive procedures. Corticosteroids, intravenous immunoglobulin, and anti-RhD immunoglobulin are the classical initial treatments for newly diagnosed ITP in adults, but these agents generally cannot induce a long-term response in most patients. Subsequent treatments for patients who fail the initial therapy include thrombopoietic agents, rituximab, fostamatinib, splenectomy, and several older immunosuppressive agents. Other potential therapeutic agents, such as inhibitors of Bruton's tyrosine kinase and neonatal Fc receptor, are currently under clinical evaluation. An optimized treatment strategy should aim at elevating the platelet counts to a safety level with minimal toxicity and improving patient health-related quality of life, and always needs to be tailored to the patients and disease phases. In this review, we address the concepts of adult ITP diagnosis and management and provide a comprehensive overview of current therapeutic strategies under general and specific situations.

Efficacy and safety of cyclosporine-based regimens for primary immune thrombocytopenia: a systematic review and meta-analysis

OBJECTIVE

To conduct a meta-analysis assessing the efficacy and safety of cyclosporine-based combinations for primary immune thrombocytopenia (ITP).

METHODS

Randomized controlled clinical trials were collected by systematically searching databases (PubMed®, MEDLINE®, EMBASE, The Cochrane Library, China National Knowledge Infrastructure) from inception to June 2022. All studies included patients with ITP who received cyclosporine-based regimens. We performed comprehensive analyses of the overall response rate (ORR), complete response (CR) rate, partial response (PR) rate, relapse rate, platelet count, and adverse drug reaction (ADR) rate.

RESULTS

Seven studies (n = 418) were ultimately included. According to a fixed-effects model, cyclosporine-based combinations improved the ORR and CR rate and reduced the relapse rate. The ADR rate was not increased in the cyclosporine-based combination group. Cyclosporine-based regimens effectively increased the platelet count. Subgroup analysis illustrated that cyclosporine-based combinations were linked to higher ORRs in both children (odds ratio [OR] = 5.74, 95% confidence interval [CI] = 1.79-18.41) and adults (OR = 5.46, 95% CI = 2.48-12.02) and a higher CR rate in adults (OR = 2.97, 95% CI = 1.56-5.63).

CONCLUSION

Cyclosporine exhibited efficacy in the treatment of ITP without increasing the risk of ADRs.

Predictive Value of B reg and Serum IL-10 Concentration Levels for Acute ITP Progression to Chronic Phase

INTRODUCTION

Pediatric immune thrombocytopenia (ITP) is a potentially life threating autoimmune disorder with different responses to therapy and different bleeding phenotypes in critical organs. The molecular basis for the variable response has not yet been fully elucidated. This study was designed to address the predictive value of regulatory B-cell (B reg ) count and interleukin-10 (IL-10) serum levels for acute ITP patients who progress to chronic phase. The present study included 80 children with acute ITP )38 males and 42 females (with median age of 8 years and 40 matched healthy controls. Assessment of B reg (CD19 + CD24 hi CD38 hi ) was carried out by a multicolor flowcytometry, however, IL-10 serum levels were evaluated by enzyme-linked immunosorbent assay. A significant reduction of B reg percentage and a significant increase in serum IL-10 levels were identified in children with acute ITP as compared with controls ( P <0.001 for both). Fourteen ITP patients passed to chronic phase, while 66 patients achieved remission within 6 months. The absolute B reg was significantly lower, while IL-10 was significantly higher in patients with acute ITP who progressed to chronic phase in comparison with acute ITP patients who achieved complete remission. Cox proportional hazards for ITP chronicity revealed that IL-10 OR was 2.46 (confidence interval: 1.42-4.27; P =0.001) and absolute B reg OR was 0.147 (confidence interval: 0.128-0.624; P =0.005) in the peripheral blood. Therefore, they could predict chronicity in ITP cases.

CONCLUSION

Reduced B reg count and elevated IL-10 levels in patients with acute ITP at diagnosis can predict chronicity.

Regulatory T cells are replenished in the splenic microenvironment of patients with immune thrombocytopenia by treatment with thrombopoietin receptor agonists

Therapeutic management of patients with immune thrombocytopenia (ITP) remains challenging; however, thrombopoietin receptor agonists (TPO-RAs) have revolutionised the treatment landscape of ITP. It is increasingly hypothesised that TPO-RAs may have an immune modulatory role and Pizzi and colleagues provide evidence in support of this by demonstrating that TPO-RA treatment restores the decreased regulatory T cell (Treg) numbers in the splenic microenvironment of patients with ITP. Commentary on: Pizzi M, Vianello F, Binotto G, Vianelli N, Carli G, Auteri G, et al. Thrombopoietin receptor agonists increase splenic regulatory T-cell numbers in Immune Thrombocytopenia. Br J Haematol. 2022 (Online ahead of print). DOI: 10.1111/bjh.18309.

Exploring the Potential of Eltrombopag: Room for More?

Since its introduction in clinical practice, eltrombopag (ELT) has demonstrated efficacy in heterogeneous clinical contexts, encompassing both benign and malignant diseases, thus leading researchers to make a more in-depth study of its mechanism of action. As a result, a growing body of evidence demonstrates that ELT displays many effects ranging from native thrombopoietin agonism to immunomodulation, anti-inflammatory, and metabolic properties. These features collectively explain ELT effectiveness in a broad spectrum of indications; moreover, they suggest that ELT could be effective in different, challenging clinical scenarios. We reviewed the extended ELT mechanism of action in various diseases, with the aim of further exploring its full potential and hypothesize new, fascinating indications.

Efficacy and Immunomodulating Properties of Eltrombopag in Aplastic Anemia following Autologous Stem Cell Transplant: Case Report and Review of the Literature

Thrombopoietin receptor agonists (TPO-RA) are currently indicated for the treatment of chronic immune thrombocytopenia and relapsed refractory aplastic anemia. However, the off-label use of these drugs is more and more frequent, including in the setting of aplasia secondary to chemotherapy and hemopoietic stem cell transplant (SCT). Growing evidence suggests that mechanisms of action of TPO-RA go beyond the TPO-receptor stimulation and point at the immunomodulating properties of these drugs. Here, we present a case of prolonged bone marrow aplasia secondary to autologous SCT treated with eltrombopag. We describe the clinical efficacy and the immunomodulating effect of this drug on inflammatory cytokine profile and bone marrow histology. Furthermore, we provide a review of the most recent literature highlighting the efficacy and safety of TPO-RA after SCT and chemotherapy for hematologic conditions.

Recent advances in the mechanisms and treatment of immune thrombocytopenia

Primary immune thrombocytopenia is an autoimmune disease associated with a reduced peripheral blood platelet count. The phenotype is variable with some patients suffering no bleeding whilst others have severe bleeding which may be fatal. Variability in clinical behaviour and treatment responses reflects its complex underlying pathophysiology. Historically the management has relied heavily on immune suppression. Recent studies have shown that the older empirical immune suppressants fail to alter the natural history of the disease and are associated with a poor quality of life for patients. Newer treatments, such as the thrombopoietin receptor agonists, have transformed ITP care. They have high efficacy, are well tolerated and improve patients’ quality of life. A greater understanding of the underlying pathophysiology of this disorder has helped develop a number of new targeted therapies. These include inhibitors of the neonatal Fc receptor inhibitors, Bruton tyrosine kinase and complement pathway. Here we discuss the mechanisms underlying ITP and the new approach to ITP care.

Immune Thrombocytopenic Purpura as a Hemorrhagic Versus Thrombotic Disease: An Updated Insight into Pathophysiological Mechanisms

Immune thrombocytopenic purpura (ITP) is a blood disorder characterized by a low platelet count of (less than 100 × 109/L). ITP is an organ-specific autoimmune disease in which the platelets and their precursors become targets of a dysfunctional immune system. This interaction leads to a decrease in platelet number and, subsequently, to a bleeding disorder that can become clinically significant with hemorrhages in skin, on the mucous membrane, or even intracranial hemorrhagic events. If ITP was initially considered a hemorrhagic disease, more recent studies suggest that ITP has an increased risk of thrombosis. In this review, we provide current insights into the primary ITP physiopathology and their consequences, with special consideration on hemorrhagic and thrombotic events. The autoimmune response in ITP involves both the innate and adaptive immune systems, comprising both humoral and cell-mediated immune responses. Thrombosis in ITP is related to the pathophysiology of the disease (young hyperactive platelets, platelets microparticles, rebalanced hemostasis, complement activation, endothelial activation, antiphospholipid antibodies, and inhibition of natural anticoagulants), ITP treatment, and other comorbidities that altogether contribute to the occurrence of thrombosis. Physicians need to be vigilant in the early diagnosis of thrombotic events and then institute proper treatment (antiaggregant, anticoagulant) along with ITP-targeted therapy. In this review, we provide current insights into the primary ITP physiopathology and their consequences, with special consideration on hemorrhagic and thrombotic events. The accumulated evidence has identified multiple pathophysiological mechanisms with specific genetic predispositions, particularly associated with environmental conditions.

Revolution of Disturbed Bregs and Bmems Lymphocytes Homeostasis in Children With Chronic ITP After High-dose Dexamethasone Rescue Therapy

SUMMARY

Dexamethasone is approved as second-line therapy in pediatric chronic immune thrombocytopenic purpura (ITP). Several B-cell abnormalities have been described in ITP pathogenesis.This study assessed the effects of high-dose dexamethasone (HD-DXM) on the percentages and absolute counts of CD19+CD24hiCD38hi regulatory (Bregs) and CD19+CD27+ memory B lymphocytes (Bmems) in children with chronic ITP during active bleeding.The study was a prospective case-control, included 20 children with chronic ITP and uncontrolled bleeding. Children received a single daily dose of HD-DXM for 4 days. Blood samples were withdrawn from patients just before HD-DXM therapy and on day 5 to evaluate the platelet counts and flow cytometric analysis of Bregs and Bmem. The patients' platelet counts significantly increased after 5 days of the initiation of therapy (P=0.0001). Bmems percentage and absolute counts were significantly higher in patients before treatment (P=0.0007), and decreased after HD-DXM therapy (P=0.97) compared with the controls. Bregs percentage and absolute counts were significantly lower before treatment (P=0.0003) and increased after HD-DXM (P=0.003). There is a negative correlation between platelet counts and Bregs percentage and absolute count Bmems percentage before and after HD-DXM, whereas a positive correlation between platelets and Bregs before and after dexamethasone has been reported.

CONCLUSIONS

HD-DXM reestablishes the normal Bregs/Bmems balance. This finding discloses possible involvement of Bregs and Bmems in the pathogenesis of pediatric ITP and provides a novel vision for immune modulation and treatment perspectives.

Eltrombopag in paediatric immune thrombocytopenia: Iron metabolism modulation in mesenchymal stromal cells

Immune thrombocytopenia (ITP) is an autoimmune disease caused by platelet destruction mediated by auto-antibody production. It is characterized by a compromised immune system and alteration of the inflammatory response. Mesenchymal stromal cells (MSCs) play an important role in modulating immune and inflammatory processes, exerting immune-suppressing and anti-inflammatory properties. In ITP-MSCs the activity and survival are strongly impaired. Eltrombopag (ELT) is a thrombopoietin receptor agonist approved in chronic ITP for stimulating platelet production. It has immunomodulating properties by stimulating T and B regulatory cell activity and by promoting a macrophage switch from the pro-inflammatory to the anti-inflammatory phenotype. ELT also exhibits iron-chelating properties. Iron is a crucial element involved in several physiologic processes, but its intracellular accumulation determines cell damages. Therefore, for the first time we analysed the effect of ELT on ITP-MSCs demonstrating its ability to restore survival and activity of MSCs directly and to promote their survival and proliferation indirectly, by iron metabolism modulation.

SDF-1α Facilitates Mesenchymal Stem Cells to Induce Regulatory B Cell Differentiation from Patients with Immune Thrombocytopenia

B cells play a central role in the pathogenesis of immune thrombocytopenia (ITP) by participating in humoral immunity. Meanwhile, regulatory B cells (Bregs), one subset of B cells, express negative regulatory effect on ITP. Mesenchymal stem cells (MSCs) have been demonstrated in the ability to induce immunosuppression, and stromal cell-derived factor-1α (SDF-1α) plays an important role in the migration and survival of MSCs. To investigate the mechanism of SDF-1α in controlling umbilical cord-derived MSCs (UC-MSCs) in inducing regulatory B cell differentiation of patients with ITP, we reconfirmed that SDF-1α promotes the proliferation of MSCs at the low doses of 0.05 μg/mL and 0.1 μg/mL but inhibits the proliferation and promotes the apoptosis of UC-MSCs at the high doses 0.5 μg/mL and 1 μg/mL; when UC-MSCs are cocultured with SDF-1α at 0.1 μg/mL, the decreased proportion of CD19⁺/CD24^hi/CD38^hi cells and IL-10-producing B cells (B 10 cell), considered as the Breg subset from ITP significantly enhanced, and the content of IL-10 in the supernatant is also obviously increased. The proportion of Bregs and the IL-10 secretion could be further promoted by the UC-MSCs treated with 0.1 μg/mL SDF-1α, which could also promote the miRNA-133 expression of UC-MSCs in an exosome-dependent manner; moreover, while the UC-MSCs were transfected with the miR-133 inhibitor, the proportion of induced Bregs decreased obviously when cocultured with peripheral blood mononuclear cells (PBMCs) of ITP. We conclude that UC-MSCs could effectively enhance the decreased proportion of Bregs from ITP; at appropriate concentrations, SDF-1α may promote the proliferating and survival ability of UC-MSCs and improve the production of Bregs induced by UC-MSCs through controlling miRNA-133 expression in the exosomes.

Abnormalities of bone marrow B cells and plasma cells in primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is an autoantibody-mediated hemorrhagic disorder in which B cells play an essential role. Previous studies have focused on peripheral blood (PB), but B cells in bone marrow (BM) have not been well characterized. We aimed to explore the profile of B-cell subsets and their cytokine environments in the BM of patients with ITP to further clarify the pathogenesis of the disease. B-cell subpopulations and their cytokine/chemokine receptors were detected by using flow cytometry. Plasma concentrations of cytokines/chemokines were measured by using enzyme-linked immunosorbent assay. Messenger RNA levels of B cell-related transcription factors were determined by using quantitative polymerase chain reaction. Regulatory B cell (Breg) function was assessed by quantifying their inhibitory effects on monocytes and T cells in vitro. Decreased proportions of total B cells, naive B cells, and defective Bregs were observed in patients with ITP compared with healthy controls (HCs), whereas an elevated frequency of long-lived plasma cells was found in BM of autoantibody-positive patients. No statistical difference was observed in plasmablasts or in short-lived plasma cells between patients with ITP and HCs. The immunosuppressive capacity of BM Bregs from patients with ITP was considerably weaker than HCs. An in vivo study using an active ITP murine model revealed that Breg transfusion could significantly alleviate thrombocytopenia. Moreover, overactivation of CXCL13-CXCR5 and BAFF/APRIL systems were found in ITP patient BM. Taken together, B-cell subsets in BM were skewed toward a proinflammatory profile in patients with ITP, suggesting the involvement of dysregulated BM B cells in the development of the disease.

Very Early Increased Platelet Count within a Week after Initiation of High-Dose Dexamethasone Treatment Is Associated with Long-Term Response in Newly Diagnosed Immune Thrombocytopenia Patients

To evaluate the long-term efficacy of high-dose dexamethasone (HD-DXM) treatment for immune thrombocytopenia (ITP), we retrospectively analysed 36 newly diagnosed ITP patients treated with HD-DXM as a first-line treatment. An initial response was obtained in 23 (63.9%) patients, including 11 with a complete response (CR) and 12 with a partial response (PR). Six months after HD-DXM treatment, 26 of 33 (78.8%) evaluable patients achieved objective responses, including 18 CR and 8 PR. Among 13 patients without initial response, very early increased platelet count within a week (VEIP) was observed in 7 patients, 5 (71.4%) of whom achieved a response at 6 months. In 29 patients who had available platelet count within a week, patients showing VEIP revealed longer survival than those who did not (p = 0.026). HD-DXM was an effective treatment for newly diagnosed ITP patients. VEIP after HD-DXM treatment initiation was associated with a long-term objective response in newly diagnosed ITP patients.

An Update on Pediatric Immune Thrombocytopenia (ITP): Differentiating Primary ITP, IPD, and PID

Immune thrombocytopenia (ITP) is the most common acquired thrombocytopenia in children and is caused by both immune-mediated decreased platelet production and increased platelet destruction. In the absence of a diagnostic test, ITP must be differentiated from other thrombocytopenic disorders, including inherited platelet disorders (IPD). In addition, a diagnosis of secondary ITP due to a primary immune deficiency (PID) with immune dysregulation may not be apparent at diagnosis but can alter management and should be considered in an expanding number of clinical scenarios. The diagnostic evaluation of children with thrombocytopenia will vary based on the clinical history and laboratory features. Access to genotyping has broadened the ability to specify the etiology of thrombocytopenia, while increasing access to immunophenotyping, functional immunologic and platelet assays, and biochemical markers has allowed for more in-depth evaluation of patients. With this greater availability of testing, diagnostic algorithms in patients with thrombocytopenia have become complex. In this article, we highlight the diagnostic evaluation of thrombocytopenia in children with a focus on ITP, including consideration of underlying genetic and immune disorders, and utilize hypothetical patient cases to describe disease manifestations and strategies for treatment of pediatric ITP.

Potential Diagnostic Approaches for Prediction of Therapeutic Responses in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder in which, via unresolved mechanisms, platelets and megakaryocytes (MKs) are targeted by autoantibodies and/or T cells resulting in increased platelet destruction and impairment of MK function. Over the years, several therapeutic modalities have become available for ITP, however, therapeutic management has proven to be very challenging in several cases. Patients refractory to treatment can develop a clinically worsening disease course, treatment-induced toxicities and are predisposed to development of potentially life-endangering bleedings. It is therefore of critical importance to timely identify potential refractory patients, for which novel diagnostic approaches are urgently needed in order to monitor and predict specific therapeutic responses. In this paper, we propose promising diagnostic investigations into immune functions and characteristics in ITP, which may potentially be exploited to help predict platelet count responses and thereby distinguish therapeutic responders from non-responders. This importantly includes analysis of T cell homeostasis, which generally appears to be disturbed in ITP due to decreased and/or dysfunctional T regulatory cells (Tregs) leading to loss of immune tolerance and initiation/perpetuation of ITP, and this may be normalized by several therapeutic modalities. Additional avenues to explore in possible prediction of therapeutic responses include examination of platelet surface sialic acids, platelet apoptosis, monocyte surface markers, B regulatory cells and platelet microparticles. Initial studies have started evaluating these markers in relation to response to various treatments including glucocorticosteroids (GCs), intravenous immunoglobulins (IVIg) and/or thrombopoietin receptor agonists (TPO-RA), however, further studies are highly warranted. The systematic molecular analysis of a broad panel of immune functions may ultimately help guide and improve personalized therapeutic management in ITP.

Increasing numbers of CD19 + CD24highCD38high regulatory B cells and pre-germinal center B cells reflect activated autoimmunity and predict future treatment response in patients with untreated immune thrombocytopenia

The pathophysiology of immune thrombocytopenia (ITP) is poorly understood, particularly aspects regarding abnormal homeostasis and dysregulation of B cells. In this study, we analyzed peripheral lymphocyte subsets in patients with untreated ITP and healthy controls, and examined correlations between cell percentages/counts and titers of serum cytokines and antibodies. We also compared ITP patients who later required second-line therapies and those who did not. The percentages of CD19 + CD24^highCD38^high regulatory B cells, pre-germinal center (GC) B cells, and plasmablast-like B cells were significantly higher in ITP patients than in healthy controls. Absolute counts of regulatory B cells and pre-GC B cells were significantly higher in those who needed second-line therapies. In addition, serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) levels and platelet-associated immune globulin G antibody titers correlated positively with regulatory B cell, pre-GC B cell, and auto-reactive B cell counts. Serum interferon-α (IFN-α) levels were elevated in four ITP patients with high auto-reactive B cell counts. These results indicate that increases in regulatory B cells and pre-GC B cells may reflect activated autoimmunity induced by BAFF and/or IFN-α. Consequently, evaluation of B cell subsets in untreated ITP patients may predict treatment response.

Elucidating the Mechanism of Action of the Attributed Immunomodulatory Role of Eltrombopag in Primary Immune Thrombocytopenia: An In Silico Approach

Eltrombopag is a thrombopoietin receptor (MPL) agonist approved for the treatment of primary immune thrombocytopenia (ITP). Recent evidence shows that some patients may sustain platelet counts following eltrombopag discontinuation. The systemic immunomodulatory response that resolves ITP in some patients could result from an increase in platelet mass, caused either by the direct action of eltrombopag on megakaryocytes through MPL stimulation, or potential MPL-independent actions on other cell types. To uncover the possible mechanisms of action of eltrombopag, in silico analyses were performed, including a systems biology-based approach, a therapeutic performance mapping system, and structural analyses. Through manual curation of the available bibliography, 56 key proteins were identified and integrated into the ITP interactome analysis. Mathematical models (94.92% mean accuracy) were obtained to elucidate potential MPL-dependent pathways in non-megakaryocytic cell subtypes. In addition to the effects on megakaryocytes and platelet numbers, the results were consistent with MPL-mediated effects on other cells, which could involve interferon-gamma, transforming growth factor-beta, peroxisome proliferator-activated receptor-gamma, and forkhead box protein P3 pathways. Structural analyses indicated that effects on three apoptosis-related proteins (BCL2L1, BCL2, BAX) from the Bcl-2 family may be off-target effects of eltrombopag. In conclusion, this study proposes new hypotheses regarding the immunomodulatory functions of eltrombopag in patients with ITP.

Downregulation of B regulatory cells and upregulation of T helper 1 cells in children with Gaucher disease undergoing enzyme replacement therapy

Gaucher disease (GD) involves a broad spectrum of immunological cells, including T helper (Th) cells and regulatory B cells (Bregs), which function to resolve the immune response and inhibit excessive inflammation. This study aimed to explore T helper cells, B cells, and Bregs in GD children undergoing enzyme replacement therapy (ERT). Our study included 20 GD patients; six patients were categorized as type 1 and 14 as type 3 GD. All patients were on regular ERT. Twenty healthy children were enrolled as controls. All patients and controls were subjected to complete blood analysis, abdominal ultrasound, and flow cytometric detection of T helper cells, B cells, and Bregs. Despite undergoing ERT, CD4+ T helper lymphocytes and Bregs were still significantly lower in patients with GD compared with the controls. Th1 and B cells were more in the patients than in the healthy controls. Lower levels of Bregs were found in type 3, compared with type 1 patients. Increased platelet count was directly associated with increased levels of Bregs and lower levels of B cells. Elevated children's height was also accompanied by decreasing levels of Th1. Our results propose that ERT in GD is associated with partial improvement in immune status, and long-term ERT might be needed for the restoration of the desired immune response levels. Levels of Bregs and Th1 can be employed for monitoring improvement of immune status in GD patients undergoing ERT.

An update on the pathophysiology of immune thrombocytopenia

: Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder mediated by antiplatelet autoantibodies and antigen-specific T cells that either destroy platelets peripherally in the spleen or impair platelet production in the bone marrow. There have been a plethora of publications relating to the pathophysiology of ITP and since January of 2019, at least 50 papers have been published on ITP pathophysiology.

PURPOSE OF REVIEW

To summarize the literature relating to the pathophysiology of ITP including the working mechanisms of therapies, T-cell and B-cell physiology, protein/RNA/DNA biochemistry, and animal models in an attempt to unify the perceived abnormal immune processes.

RECENT FINDINGS

The most recent pathophysiologic irregularities associated with ITP relate to abnormal T-cell responses, particularly, defective T regulatory cell activity and how therapeutics can restore these responses. The robust literature on T cells in ITP points to the notion that ITP is a disease initiated by faulty self-tolerance mechanisms very much like that of other organ-specific autoimmune diseases. There is also a large literature on new and existing animal models of ITP and these will be discussed. It appears that understanding how to specifically modulate T cells in patients with ITP will undoubtedly lead to effective antigen-specific therapeutics.

CONCLUSIONS

ITP is predominately a T cell disorder which leads to a breakdown in self tolerance mechanisms and allows for the generation of anti-platelet autoantibodies and T cells. Novel therapeutics that target T cells may be the most effective way to perhaps cure this disorder.

The Role of Regulatory B cells in Kidney Diseases

B cells, commonly regarded as proinflammatory antibody-producing cells, are detrimental to individuals with autoimmune diseases. However, in recent years, several studies have shown that regulatory B (Breg) cells, an immunosuppressive subset of B cells, may exert protective effects against autoimmune diseases by secretion of inhibitory cytokines such as IL-10. In practice, Breg cells are identified by their production of immune-regulatory cytokines, such as IL-10, TGF-β, and IL-35, however, no specific marker or Breg cell-specific transcription factor has been identified. Multiple phenotypes of Breg cells have been found, whose functions vary according to their phenotype. This review summarizes the discovery, phenotypes, development, and function of Breg cells and highlights their potential therapeutic value in kidney diseases.

Reduced IL-35 in patients with immune thrombocytopenia

: The occurrence and development of primary immune thrombocytopenia is closely related to autoimmune imbalanced. Thus, we conducted the current study to investigate the modulation of IL-35, a newly identified immunological self-tolerance factor on immune thrombocytopenic purpura (ITP). We were enrolled peripheral blood in 21 adult healthy volunteers, 21 active primary ITP patients and 16 ITP patients in remission. In the same period, bone marrow plasma was drawn from active primary ITP patients and 16 bone marrow donors. Enzyme-linked immunoassay was used to measure IL-35 levels in bone marrow mononuclear cells and peripheral blood mononuclear cells. Real-time quantitative PCR was used to study the mRNA expression levels of p35, Epstein-Barr virus-induced gene 3 in bone marrow mononuclear cells and peripheral blood mononuclear cells. Compared with the normal group, IL-35 levels of in ITP patients were decreased significantly. IL-35 level in bone marrow plasma was decreased more significantly than that in peripheral blood plasma at the same stage. The results showed that plasma IL-35 levels were significantly decreased in patients with active ITP compared with those of control individuals, and IL-35 levels in bone marrow plasma were decreased more significantly compared with those at the same stage. The pathogenesis of ITP is associated with decreased IL-35 levels. Further studies are needed to expand sample content and explore more in-depth investigate a possible role of IL-35 in the pathogenesis and course of ITP.

Immune cytopenias as a continuum in inborn errors of immunity: An in-depth clinical and immunological exploration

BACKGROUND

Immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AIHA), and autoimmune neutropenia (AIN) are disorders characterized by immune-mediated destruction of hematopoietic cell lineages. A link between pediatric immune cytopenias and inborn errors of immunity (IEI) was established in particular in the combined and chronic forms.

OBJECTIVE

Aim of this study is to provide clinical-immunological parameters to hematologists useful for a prompt identification of children with immune cytopenias deserving a deeper immunological and genetic evaluation.

METHODS

We retrospectively collected 47 pediatric patients with at least one hematological disorder among which persistent/chronic ITP, AIHA, and AIN, aged 0-18 years at onset of immune cytopenias and/or immune-dysregulation. The cohort was divided into two groups (IEI+ and IEI-), based on the presence/absence of underlying IEI diagnosis. IEI+ group, formed by 19/47 individuals, included: common variable immune deficiency (CVID; 9/19), autoimmune lymphoproliferative syndrome (ALPS; 4/19), DiGeorge syndrome (1/19), and unclassified IEI (5/19).

RESULTS

IEI prevalence among patients with ITP, AIHA, AIN, and Evans Syndrome was respectively of 42%, 64%, 36%, and 62%. In IEI+ group the extended immunophenotyping identified the presence of statistically significant (p < .05) specific characteristics, namely T/B lymphopenia, decrease in naїve T-cells%, switched memory B-cells%, plasmablasts%, and/or immunoglobulins, increase in effector/central memory T-cells% and CD21low B-cells%. Except for DiGeorge and three ALPS patients, only 2/9 CVID patients had a molecular diagnosis for IEI: one carrying the pathogenic variant CR2:c.826delT, the likely pathogenic variant PRF1:c.272C> and the compound heterozygous TNFRSF13B variants p.Ser144Ter (pathogenic) and p.Cys193Arg (variant of uncertain significance), the other one carrying the likely pathogenic monoallelic variant TNFRSF13B:p.Ile87Asn.

CONCLUSION

The synergy between hematologists and immunologists can improve and fasten diagnosis and management of patients with immune cytopenias through a wide focused clinical/immunophenotypical characterization, which identifies children worthy of IEI-related molecular analysis, favouring a genetic IEI diagnosis and potentially unveiling new targeted-gene variants responsible for IEI phenotype.

Imbalance of T Lymphocyte Subsets in Adult Immune Thrombocytopenia

BACKGROUND

Primary immune thrombocytopenia (ITP) is defined as an acquired autoimmune disease characterized by isolated thrombocytopenia. This work is to further clarify the relationship between T cell immune dysfunction and the pathogenesis of ITP.

METHODS

37 adult patients with ITP were selected and were classified into newly diagnosed ITP (nITP, n = 13), persistent ITP (pITP, n = 6) and chronic ITP (cITP n = 18). The frequency of cytotoxic T lymphocytes (Tc1, Tc2, and Tc17) and helper T cells (Th1, Th2, and Th17), Tregs, and the expression of chemokine receptors and PD-1 on CD4+ T cells were investigated by flow cytometry. Plasma levels of T cell-related cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, IL-17) were measured by cytometric beads array (CBA).

RESULTS

The percentage of Tc1 in cITP was greatly higher than nITP and healthy controls (p < 0.05, p < 0.01). The percentage of Treg in nITP and cITP groups was remarkably lower than those in healthy control group (p < 0.05, p < 0.001); and according to platelet count analysis (PLT<50x109/L or PLT>50x109/L), Treg cells in ITP group were significantly lower than those in healthy control group (p < 0.001, p < 0.05). The percentage of CD4+CXCR3+ of cITP was significantly higher than healthy controls and nITP (p < 0.01, p < 0.05). The percentage of CD4+CCR6+ in cITP was significantly higher than healthy controls and nITP (p < 0.001, p < 0.05). The expression of PD-1 in cITP patients was higher than healthy control (p < 0.05), but there was no significant difference among nITP, pITP and cITP (p = 0.25). The levels of IL-2, IFN-γ and TNFα in nITP group and cITP group were significantly higher than those in healthy control group (p < 0.01, p < 0.05; p < 0.01, p < 0.05; p < 0.05, p < 0.05), and the level of IL-10 in nITP group was significantly higher than that in pITP group (p < 0.05).

CONCLUSION

Our results suggest that T lymphocyte immune dysfunction does exist in adult ITP patients and plays an important role in the pathogenesis of ITP.

Effects of Eltrombopag on In Vitro Macrophage Polarization in Pediatric Immune Thrombocytopenia

Immune Thrombocytopenia (ITP) is an autoimmune disease characterized by autoantibodies-mediated platelet destruction, a prevalence of M1 pro-inflammatory macrophage phenotype and an elevated T helper 1 and T helper 2 lymphocytes (Th1/Th2) ratio, resulting in impairment of inflammatory profile and immune response. Macrophages are immune cells, present as pro-inflammatory classically activated macrophages (M1) or as anti-inflammatory alternatively activated macrophages (M2). They have a key role in ITP, acting both as effector cells, phagocytizing platelets, and, as antigen presenting cells, stimulating auto-antibodies against platelets production. Eltrombopag (ELT) is a thrombopoietin receptor agonist licensed for chronic ITP to stimulate platelet production. Moreover, it improves T and B regulatory cells functions, suppresses T-cells activity, and inhibits monocytes activation. We analyzed the effect of ELT on macrophage phenotype polarization, proposing a new possible mechanism of action. We suggest it as a mediator of macrophage phenotype switch from the M1 pro-inflammatory type to the M2 anti-inflammatory one in paediatric patients with ITP, in order to reduce inflammatory state and restore the immune system function. Our results provide new insights into the therapy and the management of ITP, suggesting ELT also as immune-modulating drug.

Glucocorticoid treatment in patients with newly diagnosed immune thrombocytopenia switches CD14++ CD16+ intermediate monocytes from a pro-inflammatory to an anti-inflammatory phenotype

Immune thrombocytopenia (ITP) is thought to result from an aberrant adaptive autoimmune response, involving autoantibodies, B and T lymphocytes, directed at platelets and megakaryocytes. Previous reports have demonstrated skewed CD4⁺ T-helper subset distribution and enhanced production of pro-inflammatory cytokines such as interleukin 17A and interferon gamma. The role of monocytes (MCs) in ITP is less widely described, but innate immune cells have a role in shaping CD4⁺ T-cell phenotypes. Glucocorticoids (GCs) are commonly used for first-line ITP treatment and modulate a broad range of immune cells including T cells and MCs. Using multiparameter flow cytometry analysis, we demonstrate the expansion of intermediate MCs (CD14⁺⁺ CD16⁺ ) in untreated patients with newly diagnosed ITP, with these cells displaying a pro-inflammatory phenotype, characterised by enhanced expression of CD64 and CD80. After 2 weeks of prednisolone treatment (1 mg/kg daily), the proportion of intermediate MCs reduced, with enhanced expression of the anti-inflammatory markers CD206 and CD163. Healthy control MCs were distinctly different than MCs from patients with ITP before and after GC treatment. Furthermore, the GC-induced phenotype was not observed in patients with chronic ITP receiving thrombopoietin receptor agonists. These data suggest a role of MCs in ITP pathogenesis and clinical response to GC therapy.

Inhibition of Glycogen Synthase Kinase 3β Increases the Proportion and Suppressive Function of CD19+CD24hiCD27+ Breg Cells

CD19⁺CD24^hiCD27⁺ memory Breg cells exhibit decreased abundance in patients with chronic graft-versus-host disease (cGVHD) after liver transplantation and produce less IL-10 than those from patients without cGVHD and healthy donors. Due to the lack of Breg cells and the difficulty in expanding them in vitro, in mouse models and early human clinical trials, the adoptive transfer of Breg cells to autoimmune diseases is greatly restricted. Glycogen synthase kinase 3β (GSK-3β) is a multifunctional serine/threonine (ser/thr) protein kinase that can participate in B cell growth, metabolic activity, and proliferation. Phosphoprotein array analysis showed that p-GSK-3β-s9 was highly expressed in mBreg cells. Furthermore, here, we demonstrated that GSK-3β expression in mBreg cells is lower than that observed in B cells by flow cytometry. We found that the treatment of B cells with the specific GSK-3β inhibitor SB216763 can significantly increase the proportion and immunosuppressive function of mBreg cells in vitro. Nuclear factor of activated T cells (NFAT) is one of a pivotal regulator of gene expression in adaptive immune system. Here, we observed that inhibition of GSK-3β by SB216763 results in enhanced expression of NFATc1 in B cells, which is essential in regulating the ability of B cells to secrete IL-10. By constructing a xGVHD mouse model, we observed that SB216763-treated mBreg cells effectively prevent xenogeneic GVHD. Here we propose a novel strategy using SB216763 to inhibit GSK-3β and then enhance the proportion and immunosuppressive function of mBreg cells by increasing the expression of NFATc1. This approach may be used as a therapy to ameliorate GVHD and inflammatory diseases.

Immunomodulatory cytokine interleukin-35 and immune thrombocytopaenia

Considerable attention has been paid to interleukin (IL)-35 because of its immunosuppressive effects in a variety of autoimmune diseases. IL-35, a recently identified cytokine of the IL-12 family, is a negative regulatory factor secreted by IL-35-inducible regulatory T cells (iTr35 cells) and the recently reported regulatory B cells (Breg cells). Four biological effects of IL-35 have been discovered in vitro and in vivo: (i) suppression of T cell proliferation; (ii) conversion of naive T cells into iTr35 cells; (iii) downregulation of type 17 helper T (Th17) cells; and (iv) conversion of Breg cells into a Breg subset that produces IL-35 and IL-10. IL-35 plays an important role in a variety of autoimmune diseases, such as rheumatoid arthritis, allergic asthma and systemic lupus erythematosus. Primary immune thrombocytopaenia (ITP), which is characterized by isolated thrombocytopaenia and mild mucocutaneous to life-threatening bleeding, is an autoimmune disease with complex dysregulation of the immune system. Both antibody-mediated and/or T cell-mediated platelet destruction are key processes. In addition, impairment of T cells and cytokine imbalances have now been recognized to be important. This review summarizes the immunomodulatory effects of IL-35 and its role in the pathogenesis of ITP as mediated by T and B cells.

High-dose dexamethasone plus recombinant human thrombopoietin vs high-dose dexamethasone alone as frontline treatment for newly diagnosed adult primary immune thrombocytopenia: A prospective, multicenter, randomized trial

We conducted a prospective, multicenter, randomized, controlled clinical trial to compare the efficacy and safety of high-dose dexamethasone (HD-DXM) plus recombinant human thrombopoietin (rhTPO), vs HD-DXM alone in newly diagnosed adult immune thrombocytopenia (ITP) patients. Enrolled patients were randomly assigned to receive DXM plus rhTPO or DXM monotherapy. Another 4-day course of DXM was repeated if response was not achieved by day 10 in both arms. One hundred patients in the HD-DXM plus rhTPO arm and 96 patients in the HD-DXM monotherapy arm were included in the full analysis set. So, HD-DXM plus rhTPO resulted in a higher incidence of initial response (89.0% vs 66.7%, P < .001) and complete response (CR, 75.0% vs 42.7%, P < .001) compared with HD-DXM monotherapy. Response rate at 6 months was also higher in the HD-DXM plus rhTPO arm than that in the HD-DXM monotherapy arm (51.0% vs 36.5%, P = .02; sustained CR: 46.0% vs 32.3%, P = .043). Throughout the follow-up period, the overall duration of response was greater in the HD-DXM plus rhTPO arm compared to the HD-DXM monotherapy arm (P = .04), as estimated by the Kaplan-Meier analysis. The study drugs were generally well tolerated. In conclusion, the combination of HD-DXM with rhTPO significantly improved the initial response and yielded favorable SR in newly diagnosed ITP patients, thus could be further validated as a frontline treatment for ITP. This study is registered as clinicaltrials.gov identifier: NCT01734044.

Cellular immune dysregulation in the pathogenesis of immune thrombocytopenia

: Immune thrombocytopenia (ITP) is an acquired autoimmune hemorrhagic disease characterized by immune-mediated increased platelet destruction and decreased platelet production, resulting from immune intolerance to autoantigen. The pathogenesis of ITP remains unclear, although dysfunction of T and B lymphocytes has been shown to be involved in the pathogenesis of ITP. More recently, it is found that dendritic cells, natural killer, and myeloid-derived suppressor cells also play an important role in ITP. Elucidating its pathogenesis is expected to provide novel channels for the targeted therapy of ITP. This article will review the role of different immune cells in ITP.

Thrombopoietin Receptor Agonists in Children with Immune Thrombocytopenia: A New Therapeutic Era

BACKGROUND AND OBJECTIVE

Immune thrombocytopenia (ITP) is a common bleeding disorder in childhood. The management of ITP in children is controversial, requiring personalized assessment of patients and therapeutic choices. Thrombopoietin receptor agonists (TPO-RAs), eltrombopag and romiplostim, have been shown to be safe and effective for the treatment of pediatric ITP. The aim of our research is to define the role of thrombopoietin receptor agonists in the management of pediatric ITP.

METHODS

This review focuses on the use of TPO-RAs in pediatric ITP, in randomized trials and in clinical routine, highlighting their key role in the management of the disease.

RESULTS

Eltrombopag and romiplostim appear effective treatment options for children with ITP. Several clinical studies have assessed that the use of TPO-RAs increases platelet count, decreases bleeding symptoms and improves health-related quality of life. Moreover, TPO-RAs are well tolerated with minor side effects.

CONCLUSION

Although long term efficacy and safety of TPO-RAs still require further investigations, their use is gradually expanding in the clinical practice of children with ITP.

Deficit of circulating CD19+ CD24hi CD38hi regulatory B cells in severe aplastic anaemia

Immune aplastic anaemia (AA) is caused by cytotoxic T lymphocytes (CTLs) that destroy haematopoietic stem and progenitor cells. Enhanced type 1 T helper (Th1) responses and reduced regulatory T cells (Tregs) are involved in the immune pathophysiology. CD24^hiCD38^hi regulatory B cells (Bregs) suppress CTLs and Th1 responses, and induce Tregs via interleukin 10 (IL‐10). We investigated circulating B‐cell subpopulations, including CD24^hiCD38^hi Bregs, as well as total B cells, CD4⁺ T cells, CD8⁺ T cells and natural killer cells in 104 untreated patients with severe and very severe AA, aged ≥18 years. All patients were treated with standard immunosuppressive therapy (IST) plus eltrombopag. CD24^hiCD38^hi Bregs were markedly reduced in patients with AA compared to healthy individuals, especially in very severe AA, but residual Bregs remained functional, capable of producing IL‐10; total B‐cell counts and the other B‐cell subpopulations were similar to those of healthy individuals. CD24^hiCD38^hi Bregs did not correlate with responses to IST, and they recovered to levels present in healthy individuals after therapy. Mature naïve B‐cell counts were unexpectedly associated with IST response. Markedly reduced CD24^hiCD38^hi Bregs, especially in very severe AA, with recovery after IST suggest Breg deficits may contribute to the pathophysiology of immune AA.

Novel scientific approaches and future research directions in understanding ITP

Diagnosis of immune thrombocytopenia (ITP) and prediction of response to therapy remain significant and constant challenges in hematology. In patients who present with ITP, the platelet count is frequently used as a surrogate marker for disease severity, and so often determines the need for therapy. Although there is a clear link between thrombocytopenia and hemostasis, a direct correlation between the extent of thrombocytopenia and bleeding symptoms, especially at lower platelet counts is lacking. Thus, bleeding in ITP is heterogeneous, unpredictable, and nearly always based on a multitude of risk factors, beyond the platelet count. The development of an evidence-based, validated risk stratification model for ITP treatment is a major goal in the ITP community and this review discusses new laboratory approaches to evaluate the various pathobiologies of ITP that may inform such a model.

Impact of CD40 gene polymorphisms on the risk of immune thrombocytopenic purpura

OBJECTIVES

To evaluate the relationship between two common single nucleotide polymorphisms (SNPs) of CD40 gene (rs1883832 C/T and rs4810485 G/T) and the risk of immune thrombocytopenia (ITP) in the Egyptian population.

METHODS

A case-control study was conducted retrospectively on 101 cases with ITP and 97 healthy subjects. Two SNPs of CD40 gene (rs1883832 C/T and rs4810485 G/T) were genotyped via Taqman allele discrimination real-time PCR. The frequencies of different genetic models of both SNPs were calculated and compared between ITP cases and controls. Linkage analysis was performed between the studied SNPs. Odds ratio (OR) and 95% confidence interval (CI) were assessed using multinomial logistic regression analysis to determine the association of CD40 gene SNPs genotypes, alleles, and haplotypes with the risk of ITP. The odds ratio was further adjusted to the confounders for risk stratification.

RESULTS

CD40 (rs1883832) TT genotype carriers have a significantly higher risk of ITP when compared to CC genotype carriers (adjusted OR: 3.792, 95%CI: 1.252-11.49, P = 0.018). T allele also represents 1.711-fold increased risk of ITP which is more evident in males (P = 0.016). No significant difference was observed in the frequency of CD40 (rs4810485 G/T) genetic models between cases and controls. Linkage disequilibrium was found between the two SNPs and revealed four main haplotypes (C-G; C-T; T-G; T-T) with a significantly higher frequency of T-G haplotype in ITP cases than in healthy controls which confers an increased risk of ITP development (OR: 2.349, 95%CI: 1.271-4.339, P = 0.006).

CONCLUSIONS

CD40 gene SNP rs1883832 is associated with an increased risk of ITP development in the Egyptian population, while the SNP rs4810485 has no association. Moreover, T-G haplotype is a risk genetic model for ITP.

Decrease in the proportion of CD24hi CD38hi B cells and impairment of their regulatory capacity in type 1 diabetes patients

B10 cells restore immune balance by producing interleukin (IL)-10. Impaired B10 cell responses are related to numerous autoimmune diseases. However, the function of B10 cells in type 1 diabetes (T1D) patients is controversial. We hypothesized that there are numerical and functional defects of B10 cells in T1D. Sixty-two patients with T1D and 74 healthy volunteers were included in our study. We showed that B10 cells in human peripheral blood belong to a CD24^hi CD38^hi B cell subpopulation. CD24^hi CD38^hi B cells from healthy individuals possessed regulatory capacity, suppressed interferon (IFN)-γ, tumor necrosis factor (TNF)-α and IL-17A production and promoted IL-4 production and forkhead box protein 3 (FoxP3) expression in CD4⁺ T cells through an IL-10-dependent mechanism. Compared to healthy controls, B10 cell percentages in T1D were significantly lower (5·6 ± 3·5 versus 6·9 ± 3·3%; P < 0·05), produced less IL-10 (15·4 ± 4·3 versus 29·0 ± 4·5%; P < 0·001) and lacked regulatory capacity. In addition, Pearson's correlation analysis showed that the frequency of circulating B10 cells was negatively correlated with the frequency of CD4⁺ IFN-γ⁺ and CD4⁺ TNF-α⁺ T cells (r = -0·248 and r = -0·283, P = 0·008 and P = 0·017, respectively), positively correlating with the frequency of CD4⁺ CD25⁺ FoxP3⁺ T cells (r = 0·247, P = 0·001). These data offer direct proof that there is a deficiency of circulating CD24^hi CD38^hi B cells in peripheral blood of patients with T1D, which participate in the T1D immune imbalance involved in the development of T1D.