Polyvalent immunoglobulin preparations inhibit pneumolysin-induced platelet destruction

Platelets play an important role in the development and progression of respiratory distress. Functional platelets are known to seal inflammatory endothelial gaps and loss of platelet function has been shown to result in loss of integrity of pulmonary vessels. This leads to fluid accumulation in the pulmonary interstitium, eventually resulting in respiratory distress. Streptococcus pneumoniae is one of the major pathogens causing community-acquired pneumonia. Previously, we have shown that its major toxin pneumolysin forms pores in platelet membranes and renders them non-functional. In vitro, this process was inhibited by polyvalent intravenous immunoglobulins (IVIG). In this study, we compared the efficacy of a standard intravenous immunoglobulin preparation (IVIG, 98% IgG; Privigen, CSL Behring, USA) and an IgM/IgA-enriched immunoglobulin preparation (21% IgA, 23% IgM, 56% IgG; trimodulin, Biotest AG, Germany) to inhibit pneumolysin-induced platelet destruction. Platelet destruction and functionality were assessed by flow cytometry, intracellular calcium release, aggregometry, platelet viability, transwell, and flow chamber assays. Overall, both immunoglobulin preparations efficiently inhibited pneumolysin-induced platelet destruction. The capacity to antagonize pneumolysin mainly depended on the final IgG content. As both polyvalent immunoglobulin preparations efficiently prevent pneumolysin-induced platelet destruction and maintain platelet function in vitro, they represent promising candidates for clinical studies on supportive treatment of pneumococcal pneumonia to reduce progression of respiratory distress.

Piperacillin–Tazobactam-Induced Immune Thrombocytopenia: A Case Report

Drug-induced immune thrombocytopenia is an isolated thrombocytopenia caused by accelerated platelet destruction from drug-dependent, platelet-reactive antibodies. Heparin-induced thrombocytopenia is the most common drug-induced immune thrombocytopenia. Common implicated antibiotics for drug-induced immune thrombocytopenia include ceftriaxone, trimethoprim–sulfamethoxazole, vancomycin, and penicillin. The platelet nadir can be less than 20 × 10 (9)/L and typically occurs within 1 to 2 weeks of exposure to the inciting drug. Although rare, drug-induced immune thrombocytopenia can be fatal. Diagnosis is made by excluding other causes of thrombocytopenia. Laboratory testing for drug-dependent antiplatelet antibodies is often helpful but not required. Thrombocytopenia typically improves within 1 to 2 days of drug discontinuation and platelet count returns to normal within a week. Identifying and discontinuing the implicated medication is key to prevention of serious complications. A patient case of drug-induced immune thrombocytopenia is described after initiation of empiric piperacillin–tazobactam for refractory right foot cellulitis in the setting of right fourth toe diabetic ulcer.

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.

Dimethyl fumarate inhibits antibody-induced platelet destruction in immune thrombocytopenia mouse

Background Immune thrombocytopenia (ITP) is an autoimmune disease characterized as a low platelet count resulting from immune-mediated platelet destruction. Dimethyl fumarate (DMF) is widely applied for the treatment of several autoimmune diseases with immunosuppressive effect. However, whether it ameliorates ITP is unclear. This study aims to evaluate whether DMF has a preventive effect on ITP in mice. Methods DMF (30, 60 or 90 mg/kg body weight) was intraperitoneally injected into mice followed by injection of rat anti-mouse integrin GPIIb/CD41antibody to induce ITP. Peripheral blood was isolated to measure platelet count and spleen mononuclear cells were extracted to measure Th1 and Treg cells along with detecting the levels of IFN-γ, and TGFβ-1 in plasma and CD68 expression in spleen by immuohistochemical staining. Additionally, macrophage cell line RAW264.7 was cultured and treated with DMF followed by analysis of cell apoptosis and cycle, and the expression of FcγRI, FcγRIIb and FcγRIV mRNA. Results DMF significantly inhibited antiplatelet antibody-induced platelet destruction, decreased Th1 cells and the expression of T-bet and IFN-γ, upregulated Treg cells and the expression of Foxp3 and TGF-β1 as well as reduced CD68 expression in the spleen of ITP mouse. DMF-treated RAW264.7 cells showed S-phase arrest, increased apoptosis and downregulated expression of FcγRI and FcγRIV. Meanwhile, in vitro treatment of DMF also decreased the expression of cyclin D1 and E2, reduced Bcl-2 level and increased Bax expression and caspase-3 activation. Conclusions In conclusion, DMF prevents antibody-mediated platelet destruction in ITP mice possibly through promoting apoptosis, indicating that it might be used as a new approach for the treatment of ITP.

Single-cell analyses of immune thrombocytopenic patients reveal multiorgan dissemination of high-affinity autoreactive plasma cells

The major therapeutic goal for immune thrombocytopenia (ITP) is to restore normal platelet counts using drugs to promote platelet production or by interfering with mechanisms responsible for platelet destruction. 80% of patients possess anti-integrin αIIbβ3 (GPIIbIIIa) IgG autoantibodies causing platelet opsonization and phagocytosis. The spleen is considered the primary site of autoantibody production by autoreactive B cells and platelet destruction. The immediate failure in ~50% of patients to recover a normal platelet count after anti-CD20 Rituximab-mediated B cell depletion and splenectomy suggest that autoreactive, rituximab-resistant, IgG-secreting B cells (IgG-SC) reside in other anatomical compartments. We analyzed >3,300 single IgG-SC from spleen, bone marrow and/or blood of 27 patients with ITP revealing high inter-individual variability in affinity for GPIIbIIIa with variations over 3 logs. IgG-SC dissemination and range of affinities were however similar per patient. Longitudinal analysis of autoreactive IgG-SC upon treatment with anti-CD38 mAb daratumumab demonstrated variable outcomes, from complete remission to failure with persistence of high-affinity anti-GPIIbIIIa IgG-SC in the bone marrow. This study demonstrates the existence and dissemination of high-affinity autoreactive plasma cells in multiple anatomical compartments of patients with ITP that may cause the failure of current therapies.

Immune Thrombocytopenia Revealing Enriched IgG-4 Peri-Renal Rosai-Dorfman Disease Successfully Treated with Rituximab: A Case Report and Literature Review.

Immune thrombocytopenia (ITP) is a rare autoimmune-mediated condition characterized by isolated thrombocytopenia (<100 G/L) after exclusion of other causes. Mostly primary, it is associated with hematological malignancy, autoimmune disorders, or infection in 20% of patients. It is exceptionally described in patients with histiocytosis, mostly in children (seven patients in literature). We report a case of a 69-year-old man with ITP leading to the diagnosis of histiocytosis. At ITP's diagnosis, the patient had elevated gamma-globulins leading to computed tomography showing bilateral peri-renal infiltration. The biopsy showed enriched IgG-4 peri-renal Rosai Dorfman disease with MAP2K1 mutation, although peri-renal infiltration is highly suggestive of Erdheim-Chester disease. This overlapping association was described in men with mutation in MAP2K1 gene. Macrophages are implicated in the pathophysiology of ITP in multiple ways, notably by the phagocytosis of opsonized platelets and their function of antigen-presenting cells able to stimulate autoreactive T cells. Histiocytic cells derivate from monocyte-macrophage lineage. Activation of macrophages in active histiocytosis is responsible for consequential platelet destruction in ITP associated histiocytosis. Finally, this case highlights a rare presentation of ITP revealing histiocytosis, both being efficiently treated with rituximab.

A Study to Evaluate Use of Platelet Indices in Hyperdestructive Thrombocytopenia: A Two-year Experience from Tertiary Care Rural Hospital

Background: Thrombocytopenia is one of the most common causes of abnormal bleeding and is defined as platelet counts < 1.5 lakhs/cumm. Three processes can cause thrombocytopenia, namely: Deficient platelet production, accelerated platelet destruction, and abnormal pooling of the platelets within the body. Of these, accelerated platelet destruction is the most common cause for thrombocytopenia and has variety of etiologies. The usefulness of bone marrow analysis in assessing accelerated platelet destruction is still debated. Therefore, a new simple and non-invasive diagnostic approach for thrombocytopenia is needed. Aims and Objectives: The present study was done with an aim to evaluate the use of platelet indices, namely, mean platelet volume (MPV), Platelet Distribution Width (PDW), and Platelet Large Cell Ratio (P-LCR) in differentiating the various causes of hyperdestructive thrombocytopenia. Materials and Methods: This was a prospective study conducted over a period of 2 years and consisted of 206 cases of hyperdestructive thrombocytopenia. After recording relevant clinical details, platelet count along with platelet indices – MPV, PDW, and P-LCR was recorded. Based on the etiopathology identified, cases were categorized into three groups: Group I: Immunologic – cases of Immune thrombocytopenic purpura (ITP), Group II: Non-immune: Cases of sepsis and other non-immune causes of platelet destruction, and Group III: Viral and parasitic infections. Platelet indices were compared between the study groups and the control group which included 100 healthy individuals. Comparison was done among the three study groups as well. Results & Conclusions: Dengue accounted for the highest number of 131 (89.72%) cases in the study. MPV, PDW, and P-LCR were significantly higher (P < 0.0001) when compared to the healthy controls except P-LCR in Group II. A statistically significant increase in MPV was noted among ITP cases when compared to other causes of thrombocytopenia. There wa

Severe Menorrhagia and Thrombocytopenia in a Patient with Pseudohypoparathyroidism

A 15-year-old female with a history of hypothyroidism presented with severe anemia and thrombocytopenia in the setting of prolonged menses. After further evaluation, she was diagnosed with pseudohypoparathyroidism Ia (PHPIa). Her symptoms improved after starting medications and receiving a platelet transfusion, but a few weeks later she returned with complaints of bleeding and dizziness and was found to be thrombocytopenic once again. Her platelet counts improved after administration of intravenous immunoglobulin (IVIG), leading us to believe she has a combined immune mediated platelet destruction in addition to platelet dysfunction associated with her PHPIa.

Surgical Control of Bleeding From Ovarian Torsion in the Setting of Immune Thrombocytopenic Purpura Without Splenectomy

Immune thrombocytopenic purpura (ITP) is a disorder caused by autoimmune antibodies which target glycoprotein IIb/IIIa complex or other platelet membrane antigens leading to platelet destruction. These platelets are then cleared by the spleen resulting in thrombocytopenia. Immune thrombocytopenic purpura affects about 1 to 6.4 cases in 100 000 children making it one of the most common causes of symptomatic thrombocytopenia in the pediatric population. It is rare that children or adolescents present with serious bleeding due to ITP. Common presentations include petechiae, bleeding gums, or bruising. Bleeding requiring hospitalization or transfusions is unusual and only occurs in approximately 5% of children. Even more uncommon is the presentation of severe bleeding complications requiring surgery for resolution. We present a case of a 17-year-old girl with acute ITP complicated by intraperitoneal hemorrhage and refractory thrombocytopenia due to ovarian cyst requiring oophorectomy.

Thrombocytopenia and Hemostatic Changes in Acute and Chronic Liver Disease: Pathophysiology, Clinical and Laboratory Features, and Management

Thrombocytopenia, defined as a platelet count <150,000/μL, is the most common complication of advanced liver disease or cirrhosis with an incidence of up to 75%. A decrease in platelet count can be the first presenting sign and tends to be proportionally related to the severity of hepatic failure. The pathophysiology of thrombocytopenia in liver disease is multifactorial, including (i) splenomegaly and subsequently increased splenic sequestration of circulating platelets, (ii) reduced hepatic synthesis of thrombopoietin with missing stimulation both of megakaryocytopoiesis and thrombocytopoiesis, resulting in diminished platelet production and release from the bone marrow, and (iii) increased platelet destruction or consumption. Among these pathologies, the decrease in thrombopoietin synthesis has been identified as a central mechanism. Two newly licensed oral thrombopoietin mimetics/receptor agonists, avatrombopag and lusutrombopag, are now available for targeted treatment of thrombocytopenia in patients with advanced liver disease, who are undergoing invasive procedures. This review summarizes recent advances in the understanding of defective but at low level rebalanced hemostasis in stable cirrhosis, discusses clinical consequences and persistent controversial issues related to the inherent bleeding risk, and is focused on a risk-adapted management of thrombocytopenia in patients with chronic liver disease, including a restrictive transfusion regimen.