Eosinophil Granulocyte and NK Cell-Mediated Platelet Destruction in Immune Thrombocytopenia

A Novel Anti-CD38 Monoclonal Antibody for Treating Immune Thrombocytopenia

BACKGROUND

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by autoantibody-mediated platelet destruction. Treatment with CM313, a novel anti-CD38 monoclonal antibody, can result in targeted clearance of CD38-positive cells, including plasma cells.

METHODS

We conducted a phase 1-2, open-label study to evaluate the safety and efficacy of CM313 in adult patients with ITP. CM313 was administered intravenously at a dose of 16 mg per kilogram of body weight every week for 8 weeks, followed by a 16-week follow-up period. The primary outcomes were adverse events and documentation of two or more consecutive platelet counts of at least 50×109 per liter within 8 weeks after the first dose of CM313. The status of peripheral-blood immune cells in patients and changes in the mononuclear phagocytic system in passive mouse models of ITP receiving anti-CD38 therapy were monitored.

RESULTS

Of the 22 patients included in the study, 21 (95%) had two consecutive platelet counts of at least 50×109 per liter during the treatment period, with a median cumulative response duration of 23 weeks (interquartile range, 17 to 24). The median time to the first platelet count of at least 50×109 per liter was 1 week (range, 1 to 3). The most common adverse events that occurred during the study were infusion-related reaction (in 32% of the patients) and upper respiratory tract infection (in 32%). After CD38-targeted therapy, the percentage of CD56dimCD16+ natural killer cells, the expression of CD32b on monocytes in peripheral blood, and the number of macrophages in the spleen of the passive mouse models of ITP all decreased.

CONCLUSIONS

In this study, anti-CD38 targeted therapy rapidly boosted platelet levels by inhibiting antibody-dependent cell-mediated cytotoxicity on platelets, maintained long-term efficacy by clearing plasma cells, and was associated with mainly low-grade toxic effects. (Funded by the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences and others; ClinicalTrials.gov number, NCT05694767).

Immune thrombocytopenia: a review on the pathogenetic role of immune cells

INTRODUCTION

Immune thrombocytopenia [ITP] is a common bleeding disorder with an isolated platelet count of less than 100 × 109/L.

AREAS COVERED

Relevant literature from 2003 to 2022 was retrieved and reviewed from the Google Scholar search engine and PubMed database. Antibodies produced by autoreactive B lymphocytes and the phagocytic function of macrophages are considered the most critical factors in platelet destruction. Also, macrophages present the antigen to T lymphocytes and activate them. Follicular helper T-cells [TFH] play a role in stimulating, differentiating, and activating autoreactive B cells, while cluster of differentiation [CD]-8+ T plays a role in platelet destruction through apoptosis. The classical pathway of the complement system also causes platelet destruction. By inhibiting platelet production, low levels of thrombopoietin and an immune response against megakaryocytes in the bone marrow worsen thrombocytopenia.

EXPERT OPINION

T-cell subset changes and an increase in activated autoreactive B cells, in addition to the function of components of the innate immune system [the complement system, dendritic cells, and natural killer cells], play a critical role in the pathogenesis of the ITP. Accurate detection of these changes may lead to developing new therapeutic strategies and identifying better prognostic/diagnostic factors.

Efficiency and safety of eltrombopag for multi-line failed Chinese patients with immune thrombocytopenia: cases with decreased megakaryocyte response well from single-center experience

Immune thrombocytopenia (ITP) was defined using the International Consensus Guidelines as a platelet count <100×10⁹/L in the absence of other causes or disorders that may be associated with thrombocytopenia. For patients without response to first-line treatment or refractory, TPO receptor agonist (RA) is an ideal choice. This study was to evaluate the efficiency and safety of eltrombopag for multi-line failed Chinese patients with immune thrombocytopenia (ITP) and analyze the possible factors that may contribute to the differences based on personal characteristics. Thirty-five multi-line failed ITP patients who received eltrombopag treatment were enrolled retrospectively at the First Affiliated Hospital of Zhejiang Chinese Medical University from January 2018 to August 2020. The general information, peripheral hemogram changes, count of bone marrow megakaryocyte (MK), peripheral T cell subsets were recorded, the response, and adverse effects, was evaluated. Results showed that the overall, complete, and partial response rates were 54.3% (n=19), 48.6% (n=17), and 5.7% (n=2) respectively to eltrombopag in our center. The overall response rate of patients with decreased MK was 70%, which was unexpectedly higher than that of the patient with increased or normal MK count (52.9% and 40%, respectively). For patients with poorer eltrombopag response group, more NK cells were found in peripheral blood, and the patient with decreased MK have a higher level of T helper (Th) cells and regulatory T (Treg) cells. Nine eltrombopag-related adverse events were reported, and most commonly were upper respiratory tract infection (8.6%), elevated alanine transaminase (ALT, 5.7%), and venous thrombosis (5.7%). In conclusion, this study revealed that ITP patients with decreased megakaryocyte respond well to eltrombopag, and the abnormality of NK cells may play a role in patients with a poor eltrombopag response.

Immunological characteristics and effect of cyclosporin in patients with immune thrombocytopenia

Objective

Immune thrombocytopenia (ITP) is well‐known as an antibody‐mediated autoimmune disease, and it is easy to get response but often turns to relapse or refractory. Cyclosporin is a traditional immunosuppressant and had a good effect on ITP patients. In this paper, we retrospectively analyze the immunological characteristics and therapeutic effect of cyclosporin in 220 patients with ITP.

Methods

All newly diagnosed ITP patients in the Department of Hematology, Tianjin Medical University General Hospital from June 2018 to December 2020 were enrolled and divided into four groups according to the expression of autoantibodies and the occurrence of prodromal infection. The basic data and immune indexes of ITP patients in each group were collected. The clinical immunological characteristics of patients in each group and the therapeutic effect of cyclosporin in each group were analyzed.

Results

Multi‐autoantibody ITP patients were more likely to have low serum albumin and high gamma globulin, and the ratio of albumin to globulin decreased. In addition, the level of IgA and IgG increased and the level of complement C3 and C4 decreased more frequently than those in other groups. The number of CD3+T lymphocytes, especially CD3+CD4+T lymphocytes, decreased in ANA+ITP patients. The number of CD16+CD56+NK cells, pDC/DC ratio, and pDC/mDC ratio were higher than those in other groups. The expression of IL‐6 and the proportion of CD19+B lymphocytes increased in two groups of ITP patients with abnormal autoantibodies. The patients of pro‐infected group were more likely to suffer from coagulation disorder. After treatment with cyclosporin, the response rate increased and the 3‐month relapse rate decreased in all ITP patients, and the therapeutic effect of patients with high megakaryocyte number was significantly higher than that of patients with low megakaryocyte number. The impact factors that influence the effect of glucocorticoid and(or) IVIG were the number of CD3+CD8+T lymphocytes, CD4/CD8 cell ratio, and the number of CD19+B lymphocytes. The independent impact factor of cyclosporin therapeutic response rate was the number of CD3+T lymphocytes.

Conclusions

ITP is a heterogeneous disease, recurrence may occur during or rapidly after treatment. Cyclosporine included treatment can improve the effective rate of ITP and reduce the relapse rate within 3 months. The number of CD3+T lymphocytes was the only impact factor that influence the therapeutic effect of cyclosporin in ITP patients.

Diversity, localization, and (patho)physiology of mature lymphocyte populations in the bone marrow

The bone marrow (BM) is responsible for generating and maintaining lifelong output of blood and immune cells. In addition to its key hematopoietic function, the BM acts as an important lymphoid organ, hosting a large variety of mature lymphocyte populations, including B cells, T cells, natural killer T cells, and innate lymphoid cells. Many of these cell types are thought to visit the BM only transiently, but for others, like plasma cells and memory T cells, the BM provides supportive niches that promote their long-term survival. Interestingly, accumulating evidence points toward an important role for mature lymphocytes in the regulation of hematopoietic stem cells (HSCs) and hematopoiesis in health and disease. In this review, we describe the diversity, migration, localization, and function of mature lymphocyte populations in murine and human BM, focusing on their role in immunity and hematopoiesis. We also address how various BM lymphocyte subsets contribute to the development of aplastic anemia and immune thrombocytopenia, illustrating the complexity of these BM disorders and the underlying similarities and differences in their disease pathophysiology. Finally, we summarize the interactions between mature lymphocytes and BM resident cells in HSC transplantation and graft-versus-host disease. A better understanding of the mechanisms by which mature lymphocyte populations regulate BM function will likely improve future therapies for patients with benign and malignant hematologic disorders.

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.

The potential association of tumor necrosis factor-βeta (252 G/A) cytokine gene polymorphism with immune thrombocytopenic purpura among Egyptian children

OBJECTIVES

The main objective of this study was to study tumor necrosis factor beta (TNFB) + 252G/A gene polymorphism, known to be related to autoimmunity, in immune thrombocytopenia (ITP) patients. We also aimed to investigate the association between TNFB + 252G/A polymorphism and susceptibility to develop persistent/chronic ITP.

METHODS

One hundred pediatric ITP patients, as well as 50 age- and sex-matched healthy Egyptian subjects, were included. Genotyping of TNF-β gene (G252A) was done using the PCR-RFLP method.

RESULTS

TNFB allele B2 frequency was (64%, 64/100) in controls, (69%, 138/200) in ITP patients, while the frequency of the variant allele B1 was 36% (36/100) in controls, (31%, 62/200) in ITP patients. TNFB genotype frequency in ITP patients showed equal frequency for B2B2 and B1B2 genotypes, (46%, 46/100), while B1B1 frequency was 8% (8/100). Among controls, frequencies of B2B2, B1B2 and B1B1 genotypes were 36% (18/50), 56% (28/50), and 8% (4/50), respectively. Odds ratio for the risk of developing ITP revealed no statistically significant risk, associated with any allele or genotype. No association was encountered between different genotypes and age, hematological parameters, gender, stage of the disease or response to treatment.

DISCUSSION

Comparison between ITP patients and controls as regards TNFB allele and genotype frequencies showed no statistically significant difference. No increased risk for developing ITP was associated with any allele/genotype.

CONCLUSION

The risk of developing ITP was not related to the studied polymorphism.