B‐cell responses to ITP treatments Crickx, Etienne; Mahévas, Matthieu
British journal of haematology,
February 2024, 2024-02-00, 20240201, Letnik:
204, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Deficiency in regulatory B cells has been suggested in immune thrombocytopenia. In this study, Stimpson et al. emphasize the importance of considering the treatments received for immunological ...analyses.
Commentary on: Stimpson et al. Systemic immunosuppression depletes peripheral blood regulatory B cells in patients with immune thrombocytopenia. Br J Haematol 2024;204:644‐648.
Pathogenesis of immune thrombocytopenia Audia, Sylvain; Mahévas, Matthieu; Samson, Maxime ...
Autoimmunity reviews,
06/2017, Letnik:
16, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Abstract Immune thrombocytopenia (ITP) is a rare autoimmune disease due to an abnormal T cell response, notably supported by splenic T follicular helper cells, that stimulates the proliferation and ...differentiation of autoreactive B cells. The antiplatelet autoantibodies they produce facilitate platelet phagocytosis by macrophages, essentially in the spleen. Macrophages contribute to the perpetuation of the auto-immune response as the main antigen-presenting cell during ITP. CD8+ T cells also participate to thrombocytopenia by increasing platelet apoptosis. Besides this peripheral platelet destruction, inappropriate bone marrow production also exacerbates thrombocytopenia, due to an immune response against megakaryocytes. Moreover, the level of circulating thrombopoietin, the main growth factor of megakaryocytes, is low during ITP. In this review, the major mechanisms leading to thrombocytopenia, the role of the different immune cells and the different targets of treatments are described.
Summary
With prolonged life expectancy, immune thrombocytopenia (ITP) is frequent in elderly people. In this setting, ITP diagnosis is challenging because of the concern about an underlying ...myelodysplastic syndrome. Studies of older adults are lacking, and recommendations for treatment are based mainly on expert opinion. The therapeutic strategy differs from that for younger patients and must take into account the greater risk of bleeding and thrombosis, presence of comorbidities, possible impaired cognitive performance or poor life expectancy and concomitant medications, such as anticoagulant and antiplatelet therapy. Steroids and intravenous immunoglobulin (IVIg) therapy remain the first‐line treatments in elderly patients, but prolonged treatment with steroids should be avoided and IVIg treatment may lead to renal failure. Splenectomy is less effective than in young patients and risk of thrombosis is increased. Severe co‐morbidities can also contraindicate surgery. Therefore, other second‐line treatments are frequently preferred. Danazol and dapsone can be an option for the less severe ITP form. Rituximab is a good option except in patients with a history of infection or with hypogammaglobulinaemia. Thrombopoietin agonists are attractive, especially for patients with severe comorbidities or with limited life expectancy but the risk of thrombosis is a concern.
Immune thrombocytopenia (ITP) is an acquired bleeding disorder mediated by pathogenic autoantibodies secreted by plasma cells (PCs) in many patients. In refractory ITP patients, the persistence of ...splenic and bone marrow autoreactive long-lived PCs (LLPCs) may explain primary failure of rituximab and splenectomy respectively. The reactivation of autoreactive memory B cells generating new autoreactive PCs contributes to relapses after initial response to rituximab. Emerging strategies targeting B cells and PCs aim to prevent the settlement of splenic LLPCs with the combination of anti-BAFF and rituximab, to deplete autoreactive PCs with anti-CD38 antibodies, and to induce deeper B-cell depletion in tissues with novel anti-CD20 monoclonal antibodies and anti-CD19 therapies. Alternative strategies, focused on controlling autoantibody mediated effects, have also been developed, including SYK and BTK inhibitors, complement inhibitors, FcRn blockers and inhibitors of platelet desialylation.
Summary
Thrombopoietin‐receptor agonists (Tpo‐RAs) are highly effective in immune thrombocytopenia (ITP). Recently, cases of durable remission after Tpo‐RA discontinuation in adult ITP have been ...reported. We aimed to describe the subset of patients in whom transient Tpo‐RA therapy may induce a durable response. We studied all adults with primary ITP treated with at least one Tpo‐RA over a 5‐year period (n = 54) and seen at one of three participating referral centres in France. Tpo‐RAs were discontinued in 20 of 28 patients who achieved a complete response. We excluded six patients because a previous treatment at the start of Tpo‐RA treatment may have interfered with the response. Overall, eight patients with chronic ITP showed a sustained response median follow‐up: 13·5 months (range 5–27 months). We could not identify a predictive factor of sustained response. In conclusion, a substantial proportion of ITP patients receiving Tpo‐RAs can maintain a durable response after treatment discontinuation.
B-cell depletion with anti-CD20 monoclonal antibodies is widely used for the treatment of autoimmune diseases. This review will discuss mechanisms contributing to success or failure of B-cell ...depletion therapy in antibody-mediated autoimmune diseases. It will also explain how key information about disease pathogeny can be provided by the different outcomes observed after B-cell depletion therapy. These findings provide the basis for future innovative therapeutic strategies aiming at an optimized B cell and/or plasma cell depletion to increase long-term disease remission.
Primary immune thrombocytopenia (ITP) is a disorder caused by autoantibody-mediated platelet destruction and decreased platelet production. Rituximab, a B cell-depleting agent, has become the ...first-line treatment for ITP; however, patients with refractory disease usually require splenectomy. We identified antibody-secreting cells as the major splenic B cell population that is resistant to rituximab. The phenotype, antibody specificity, and gene expression profile of these cells were characterized and compared to those of antibody-secreting cells from untreated ITP spleens and from healthy tissues. Antiplatelet-specific plasma cells (PC) were detected in the spleens of patients with ITP up to 6 months after rituximab treatment, and the PC population displayed a long-lived program similar to the one of bone marrow PC, thus explaining for most of these patients the absence of response to rituximab and the response to splenectomy. When analyzed by multiplex PCR at the single-cell level, normal splenic PC showed a markedly different gene expression profile, with an intermediate signature, including genes characteristic of both long-lived PC and proliferating plasmablasts. Surprisingly, long-lived PC were not detected in untreated ITP spleens. These results suggest that the milieu generated by B cell depletion promotes the differentiation and settlement of long-lived PC in the spleen.
In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC ...responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs.
Display omitted
•Vaccination boosts high-affinity RBD memory B cells (MBCs) in COVID-19-recovered patients•Boosted MBCs retain their diversity and express potent variant-neutralizing antibodies•SARS-CoV-2-naive individuals show low serum neutralization of variants after vaccination•Maturation of MBCs in naive individuals allows them to respond to variants of concern
To better understand B cell responses to SARS-CoV-2 mRNA vaccination, Sokal et al. analyzed memory B cells from COVID-19-recovered and naive individuals. In recovered individuals, vaccination amplifies a broad repertoire of matured MBCs and generates variant-neutralizing plasma cells. In naive individuals, vaccination induces an MBC pool containing potent neutralizing clones against all current variants of concern, including beta and delta.
PDF
