Emerging Concepts in Immune Thrombotic Thrombocytopenic Purpura

De-novo immune-mediated thrombotic thrombocytopenic purpura following surgical and non-surgical procedures: A systematic review

When de-novo immune-mediated thrombotic thrombocytopenic purpura (TTP) is diagnosed following an invasive procedure, clinical presentation patterns and outcomes are poorly defined. Therefore, in a systematic literature review of patients diagnosed with TTP following an invasive surgical or non-surgical procedure, we identified 19 studies reporting data on 25 patients. These data suggest that 1) TTP pathogenesis likely begins prior to the invasive procedure, 2) patients experience significant diagnostic delays, and 3) there is a high incidence of renal replacement therapy. Although invasive procedures may trigger TTP, further studies are needed to clarify the mechanisms underlying this association.

Recent advances in the management of immune thrombocytopenic purpura (ITP): A comprehensive review

Autoimmune disorders place a substantial burden on the healthcare system all over the world affecting almost 3% to 8% of the population. Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura, is a blood disorder in which the body immune system destroys platelets, leading to low platelet counts in the blood (peripheral blood platelet count < 150 × 109/L). Although the pathophysiology of ITP is not fully understood, it is believed to result from a complex interplay between hereditary and environmental variables. Certain factors, such as a low platelet count, history of bleeding, and certain comorbidities can increase the risk of severe bleeding in patients with ITP. Corticosteroids, intravenous immunoglobulin (IVIG), immunosuppressants, rituximab, and thrombopoietin receptor agonists (TPO-RAs) are some of the advanced treatments for ITP. Although these therapies may be successful, they also carry the risk of negative effects. Recently, significant advancements have been made in the understanding and treatment of ITP. There is still much to learn about the disease, and new, more effective treatments are needed. This comprehensive review offers a comprehensive assessment of recent advancements in ITP management, with a focus on active research projects, novel therapeutic targets, new treatment modalities, and areas of uncertainty and unmet needs. According to research, it is crucial to develop individualized treatment plans for ITP patients based on their age, platelet count, risk of bleeding, and comorbidities. The article also looks at how future developments in gene editing, bispecific antibody therapies, and cellular therapy may completely change the treatment of ITP.

Acquired thrombotic thrombocytopenic purpura as a clinical manifestation of pulmonary tuberculosis: a case report

Introduction

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy associated with severe ADAMTS13 deficiency that can be potentially fatal if not treated in a timely manner.

Case report

A 49-year-old previously healthy woman was admitted with a 3-month history of thoracoabdominal pain and headache associated with loss of appetite, emesis, nocturnal diaphoresis, and unintentional loss of 10 kg. On admission she presented anemia, thrombocytopenia, schistocytes in peripheral blood smear, and ADAMTS13 in 1.4%. Due to laboratory findings a diagnosis of TTP was established, and plasma exchange therapy and steroid pulses were started, with resolution of hematological alterations. Within the studies to determine etiology of TTP, pulmonary tuberculosis (TB) was found, neoplastic and autoimmune pathologies were excluded. The tetraconjugated treatment was initiated with optimal tolerance.

Conclusions

Upon clinical suspicion of TTP, plasma exchange therapy should be initiated urgently; infectious, neoplastic, or autoimmune pathologies can be triggers; in this case, pulmonary TB was confirmed.

N-Acetylcistein for thrombotic thrombocytopenic purpura: an observational case series study

Acquired thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder. N-Acetylcysteine (NAC) rapidly degrades ultra-large von Willebrand factor multimers by disrupting the disulfide bonds. We report a series of twelve consecutive patients diagnosed with acquired TTP successfully treated with high-dose NAC (150 mg/kg/day) in combination with plasma exchange and steroids. Eight patients also received rituximab. Two patients presented refractory TTP. All patients achieved a quick clinical response in a median time of 5.5 days after starting NAC and are alive after a median follow-up of 29 months. The treatment was feasible and well tolerated. These data provide further evidence of the potential benefit and safety of adding NAC to the standard of care.

Thrombotic thrombocytopenic purpura following ChAdOx1 nCov-19 vaccination: A case report

Vaccine-associated thrombotic thrombocytopenic purpura (TTP) is a rare type of acquired TTP recently reported after COVID-19 vaccination. Merely four cases are ascribed to the ChAdOx1 nCoV-19 vaccine in the medical literature till the preparation of this study. In this case report, we describe a 43-year-old man who developed symptoms of TTP four days after receiving the second dose of the ChAdOx1 nCoV-19 vaccine. Peripheral blood smear demonstrated multiple schistocytes. Given a high plasmic score, he received plasma exchange, corticosteroids, and rituximab, and later, low ADAMTS 13 activity and high-titer ADAMTS inhibition antibody confirmed the diagnosis of COVID-19 vaccine-associated TTP. COVID-19 vaccine-associated TTP is an infrequent consequence of SARS-CoV-2 vaccination but with a substantial mortality rate which must be considered as one of the crucial differential diagnoses of post-COVID-19 vaccine thrombocytopenia besides vaccine-induced immune thrombotic thrombocytopenia and Immune thrombocytopenic purpura.

Overlapping ADAMTS13 peptide binding profiles of DRB1∗08:03 and DRB1∗11:01 suggest a common etiology of immune-mediated thrombotic thrombocytopenic purpura

BACKGROUND

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is an ultra-rare autoimmune disorder caused by autoantibodies against ADAMTS13. A strong association of DRB1∗11 with iTTP and DRB1∗11-restricted T-cell epitopes in ADAMTS13 have been reported in Europeans, whereas we previously found DRB1∗08:03 as a susceptible allele in Japanese.

OBJECTIVES

The limited information is available regarding a susceptible allele and its T-cell epitopes in Japanese patients with iTTP.

MATERIALS AND METHODS

We conducted a reanalysis on iTTP-predisposing alleles using 3 distinct Japanese control groups. Subsequently, a novel human leukocyte antigen (HLA)-peptide expression assay (MHC-density assay) was used to identify the presentation of 24 ADAMTS13-derived peptides, including the regions that were identified previously by MHC-peptidome analysis and/or T-cell assays or predicted by NetMHCIIpan-4.0, to DRB1∗08:03 and DRB1∗11:01.

RESULTS

We reconfirmed the strong association of DRB1∗08:03 with iTTP, as well as the absence of the secondary risk alleles and protective alleles in Japanese iTTP, which altogether reveal that the HLA association pattern is completely different between the European and Japanese iTTP. MHC-density assay found the 3 ADAMTS13-derived peptides in the spacer domain as a potential strong binder to DRB1∗08:03. Moreover, 6 peptides in the metalloprotease, spacer, sixth thrombospondin-1 repeat, and CUB domains in ADAMTS13 showed increased presentation by both DRB1∗08:03 and DRB1∗11:01.

CONCLUSION

Altogether, the findings of distinct HLA-DR association with iTTP across populations and the presentation of common peptides by DRB1∗08:03 and DRB1∗11:01 suggest that the same ADAMTS13-derived peptides might be presented and trigger the activation of autoreactive CD4⁺ T cells, leading to production of anti-ADAMTS13 autoantibodies by autoreactive B cells.

Proximity proteomics identifies septins and PAK2 as decisive regulators of actomyosin-mediated expulsion of von Willebrand factor

In response to tissue injury, within seconds the ultra-large glycoprotein von Willebrand factor (VWF) is released from endothelial storage organelles (Weibel-Palade bodies) into the lumen of the blood vasculature, where it leads to the recruitment of platelets. The marked size of VWF multimers represents an unprecedented burden on the secretory machinery of endothelial cells (ECs). ECs have evolved mechanisms to overcome this, most notably an actomyosin ring that forms, contracts, and squeezes out its unwieldy cargo. Inhibiting the formation or function of these structures represents a novel therapeutic target for thrombotic pathologies, although characterizing proteins associated with such a dynamic process has been challenging. We have combined APEX2 proximity labeling with an innovative dual loss-of-function screen to identify proteins associated with actomyosin ring function. We show that p21 activated kinase 2 (PAK2) recruits septin hetero-oligomers, a molecular interaction that forms a ring around exocytic sites. This cascade of events controls actomyosin ring function, aiding efficient exocytic release. Genetic or pharmacological inhibition of PAK2 or septins led to inefficient release of VWF and a failure to form platelet-catching strings. This new molecular mechanism offers additional therapeutic targets for the control of thrombotic disease and is highly relevant to other secretory systems that employ exocytic actomyosin machinery.

Evaluation of thrombotic thrombocytopenic purpura and other thrombotic microangiopathies: Lessons learned from a 14-year retrospective study

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) is a clinical thrombotic microangiopathy (TMA) syndrome defined by the pentad of symptoms. Therapeutic plasma exchange with plasma replacement is an ASFA Category I modality that can reduce morbidity and mortality if initiated early. We describe a 14-year review of patients referred for plasma exchange with a suspected diagnosis of TTP.

METHODS

For 70 patients referred for urgent plasma exchange, clinical, therapeutic, and laboratory data were retrospectively analyzed, and the diagnosis was determined.

RESULTS

Fifteen of the patients were diagnosed with TTP based upon ADAMTS-13 activity with the other 51 patients having other non-TTP TMA diagnoses. The mortality rate was significant for both TTP and non-TTP TMAs. PLASMIC scores were also calculated retrospectively and were noted to have limited value. TMA is a diagnostic challenge and encompasses different syndromes with similar presentations.

CONCLUSION

Determining an accurate diagnosis, including prompt ADAMTS-13 testing, makes it possible to initiate appropriate therapy for the multiple different TMAs that can be seen in clinical practice.

Response to belimumab in thrombotic thrombocytopenic purpura associated with systemic lupus erythematosus: a case-based review

Thrombotic thrombocytopenic purpura (TTP), a life-threatening syndrome characterized by acute microangiopathic hemolytic anemia, thrombocytopenia, and visceral ischemia, can be classified as congenital TTP (inherited due to a mutation in ADAMTS13) and acquired TTP. The acquired TTP is further classified as idiopathic and secondary TTP. Systemic lupus erythematosus (SLE) is regarded as one of the most common causes of secondary TTP (SLE-TTP). In contrast to patients with idiopathic TTP, some patients with SLE-TTP, especially those diagnosed with refractory TTP, are resistant to plasma exchange and high-dose corticosteroids and usually require second-line drugs, including newly developed biologicals. Belimumab, a B-lymphocyte stimulator-specific inhibitor, was the first approved new therapy for SLE in the past 50 years. Only two cases of SLE-TTP using belimumab have been reported; however, detailed information has not been made available. Herein, we describe a 28-year-old female patient who presented with palm petechiae, strong tawny urine, and yellow stained skin and sclera, and was diagnosed with SLE-TTP supported by high anti-ANA titers; positive anti-SSA/SM; pleural effusion; decreased platelet count, hemoglobin, and complement C3/C4 counts; increased lactate dehydrogenase level, along with increased schistocytes; and a significant deficiency of ADAMTS13 activity. Belimumab (10 mg/kg) was administered after six plasma exchanges. Good efficiency and outcomes without any adverse events, SLE, or TTP relapse were observed during 12 months of follow-up. Therefore, belimumab is a promising choice for SLE-TTP management. In addition, we provide a focused review of the existing literature on the pathogenesis, diagnosis, and therapeutic strategies for SLE-TTP.