Efficacy and safety of human umbilical cord-derived mesenchymal stem cells in the treatment of refractory immune thrombocytopenia: a prospective, single arm, phase I trial.

Patients with refractory immune thrombocytopenia (ITP) frequently encounter substantial bleeding risks and demonstrate limited responsiveness to existing therapies. Umbilical cord-derived mesenchymal stem cells (UC-MSCs) present a promising alternative, capitalizing on their low immunogenicity and potent immunomodulatory effects for treating diverse autoimmune disorders. This prospective phase I trial enrolled eighteen eligible patients to explore the safety and efficacy of UC-MSCs in treating refractory ITP. The research design included administering UC-MSCs at escalating doses of 0.5 × 106 cells/kg, 1.0 × 106 cells/kg, and 2.0 × 106 cells/kg weekly for four consecutive weeks across three cohorts during the dose-escalation phase, followed by a dose of 2.0 × 106 cells/kg weekly for the dose-expansion phase. Adverse events, platelet counts, and changes in peripheral blood immunity were monitored and recorded throughout the administration and follow-up period. Ultimately, 12 (with an addition of three patients in the 2.0 × 106 cells/kg group due to dose-limiting toxicity) and six patients were enrolled in the dose-escalation and dose-expansion phase, respectively. Thirteen patients (13/18, 72.2%) experienced one or more treatment emergent adverse events. Serious adverse events occurred in four patients (4/18, 22.2%), including gastrointestinal hemorrhage (2/4), profuse menstruation (1/4), and acute myocardial infarction (1/4). The response rates were 41.7% in the dose-escalation phase (5/12, two received 1.0 × 106 cells/kg per week, and three received 2.0 × 106 cells/kg per week) and 50.0% (3/6) in the dose-expansion phase. The overall response rate was 44.4% (8/18) among all enrolled patients. To sum up, UC-MSCs are effective and well tolerated in treating refractory ITP (ClinicalTrials.gov ID: NCT04014166).

Therapeutic strategies in FcγIIA receptor-dependent thrombosis and thromboinflammation as seen in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT).

INTRODUCTION: Fcγ-receptors (FcγR) are membrane receptors expressed on a variety of immune cells, specialized in recognition of the Fc part of immunoglobulin G (IgG) antibodies. FcγRIIA-dependent platelet activation in platelet factor 4 (PF4) antibody-related disorders have gained major attention, when these antibodies were identified as the cause of the adverse vaccination event termed vaccine-induced immune thrombocytopenia and thrombosis (VITT) during the COVID-19 vaccination campaign. With the recognition of anti-PF4 antibodies as cause for severe spontaneous and sometimes recurrent thromboses independent of vaccination, their clinical relevance extended far beyond heparin-induced thrombocytopenia (HIT) and VITT. AREAS COVERED: Patients developing these disorders show life-threatening thromboses, and the outcome is highly dependent on effective treatment. This narrative literature review summarizes treatment options for HIT and VITT that are currently available for clinical application and provides the perspective toward new developments. EXPERT OPINION: Nearly all these novel approaches are based on in vitro, preclinical observations, or case reports with only limited implementation in clinical practice. The therapeutic potential of these approaches still needs to be proven in larger cohort studies to ensure treatment efficacy and long-term patient safety.

A novel mouse strain optimized for chronic human antibody administration.

Therapeutic human IgG antibodies are routinely tested in mouse models of oncologic, infectious, and autoimmune diseases. However, assessing the efficacy and safety of long-term administration of these agents has been limited by endogenous anti-human IgG immune responses that act to clear human IgG from serum and relevant tissues, thereby reducing their efficacy and contributing to immune complex­mediated pathologies, confounding evaluation of potential toxicity. For this reason, human antibody treatment in mice is generally limited in duration and dosing, thus failing to recapitulate the potential clinical applications of these therapeutics. Here, we report the development of a mouse model that is tolerant of chronic human antibody administration. This model combines both a human IgG1 heavy chain knock-in and a full recapitulation of human Fc receptor (FcγR) expression, providing a unique platform for in vivo testing of human monoclonal antibodies with relevant receptors beyond the short term. Compared to controls, hIgG1 knock-in mice mount minimal anti-human IgG responses, allowing for the persistence of therapeutically active circulating human IgG even in the late stages of treatment in chronic models of immune thrombocytopenic purpura and metastatic melanoma.

Clinical utility of the CD10+/HLA-DR+ population in bone marrow mononuclear cells from adults with immune thrombocytopenia.

Several patients with immune thrombocytopenia show good clinical courses without any major complications. However, severe bleeding complications, such as hemoptysis, gastrointestinal bleeding, and intracranial hemorrhages, are occasionally observed in some patients associated with marked thrombocytopenia; this results in 1.5-fold higher mortality for such patients compared with the general population. We report here the cases of two patients with immune thrombocytopenia whose bone marrow included a prominent cluster of differentiation (CD)10+/ human leukocyte antigen (HLA)-DR+ population and showed good response to steroid therapy. Conversely, two other patients without a CD10+/HLA-DR+ population were refractory to steroids, and one of them had a serious course. Retrospective examination of 30 patients with severe immune thrombocytopenia revealed that they had a higher percentage of CD10+/HLA-DR+ cells compared with patients with other benign hematological diseases. As differential diagnosis of immune thrombocytopenia and aplastic anemia with severe thrombocytopenia is often difficult, it may be helpful to understand whether CD10+/HLA-DR+ cells are increased. We also show the possible correlation of resistance to steroid therapy and lower percentages of CD10+/HLA-DR+ cells. It has been reported that nonresponsiveness to steroid treatment was a high risk factor for intracranial hemorrhage. Lower percentages of CD10+/HLA-DR+ cells may be a useful tool to identify patients with immune thrombocytopenia at a high risk of serious bleeding complications.

Ultrastructural findings of lung injury due to Vaccine-induced Immune Thrombotic Thrombo- cytopenia (VITT) following COVID-19 vaccination: a scanning electron microscopic study.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare new syndrome occurring after the ChAdOx1 nCoV-19 vaccine immunization. Patients with VITT are characterized by a variable clinical presentation, likewise also the outcome of these patients is very variable. Here we report the lung ultrastructural findings in the course of VITT of a 58-year-old male patient. Alveoli were mainly dilated, irregular in shape, and occupied by a reticular network of fibrin, while interalveolar septa appeared thickened. The proliferation of small capillaries gave rise to plexiform structures and pulmonary capillary hemangiomatosis-like features. Near the alveoli occupied by a dense fibrin network, the medium-sized arteries showed a modified wall and an intraluminal thrombus. This scenario looks quite similar to that found during COVID-19, where the lungs suffer from the attack of the antigen-antibodies complexes and the virus respectively. In both diseases, the final outcome is a severe inflammation, activation of the haemostatic system and fibrinolysis.

Alemtuzumab-induced red cell aplasia and other immune cytopenias: not so 'pure'.

We report on the presentation and outcome of a 28-year-old female who developed red cell aplasia following alemtuzumab therapy for relapsing remitting multiple sclerosis. The patient also developed synchronous immune thrombocytopenia and immune neutropenia, but not aplastic anemia. This patient received high dose steroids, intravenous immunoglobulin (iv.Ig), rituximab, red cell transfusions, vincristine, G-CSF, cyclosporin and mycophenolate to treat the combination of cytopenias over a period of 6 months with subsequent improvement in bone marrow function. While alemtuzumab has several recognized autoimmune complications, little is known about the potential hematological side effects. The combination of red cell aplasia, immune thrombocytic purpura and autoimmune neutropenia has not previously been described in the literature following alemtuzumab immunotherapy and highlights the importance of monthly blood monitoring post alemtuzumab administration.

Lay abstract We report a case of 28-year-old women with relapsing remitting multiple sclerosis who was treated with alemtuzumab and subsequently developed a series of autoimmune complications. Several months after completing her second course of alemtuzumab the patient became breathless and noticed bruising on her legs. On investigation she was found to be anemic and had a low platelet level (which predisposed her to bruising). In addition, her immune system was also impaired meaning she was more prone to developing opportunistic infections. The patient was treated with a variety of different medications and required blood transfusions for several months before she recovered. Despite the multiple complications the patient developed from alemtuzumab her multiple sclerosis remains stable with no new relapses 3 years following treatment.

The Mechanistic Effects and Clinical Applications of Various Derived Mesenchymal Stem Cells in Immune Thrombocytopenia.

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by persistent thrombocytopenia resulting from increased platelet destruction and a loss of autoimmune tolerance. The pathogenesis of ITP is highly complex. Although ITP may be effectively controlled with currently available medications in some patients, a subset of cases remain refractory. The application of mesenchymal stem cells (MSCs) for human hematopoietic stem cell transplantation has increasingly demonstrated that MSCs modulate innate or adaptive immunity, thus resulting in a tolerant microenvironment. Functional defects and immunomodulatory disorders have been observed after the use of bone marrow mesenchymal stem cells (BM-MSCs) from patients with ITP. Here, we summarize the underlying mechanisms and clinical applications of various derived MSCs for ITP treatment, focusing on the main mechanisms underlying the functional defects and immune dysfunction of BM-MSCs from patients with ITP. Functional effects associated with the activation of the p53 pathway include decreased activity of the phosphatidylinositol 3 kinase/Akt pathway and activation of the TNFAIP3/NF-κB/SMAD7 pathway. Immune dysfunction appears to be associated with an impaired ability of BM-MSCs to induce various types of immune cells in ITP. At present, research focusing on MSCs in ITP remains in preliminary stages. The application of autologous or exogenous MSCs in the clinical treatment of ITP has been attempted in only a small case study and must be validated in larger-scale clinical trials.

Plasma Levels of Big Endothelin-1 Are Associated with Renal Insufficiency and In-Hospital Mortality of Immune Thrombotic Thrombocytopenic Purpura.

Immune thrombotic thrombocytopenic purpura (iTTP) is caused by severe deficiency of plasma ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity. Despite advances in early diagnosis and management, the mortality rate of acute iTTP remains high in a large part of world where access to some of the most novel therapies is limited. To determine the role of plasma big endothelin-1 (bigET-1) or its bioactive product ET-1 as a biomarker and/or a pathogenic factor in acute iTTP, plasma levels of bigET-1 were determined using an immunoassay in patients with iTTP on admission and during remission, as well as in healthy controls; moreover, the biological effect of ET-1 in thrombus formation was determined by a microfluidic assay. We show that plasma levels of bigET-1 were dramatically increased in patients with acute iTTP on admission, which was significantly decreased during clinical response/remission; elevated admission levels of plasma bigET-1 were associated with low estimated glomerular filtration rate, the need for intensive care unit admission or intubation, and in-hospital mortality. Moreover, an addition of a bioactive product ET-1 to cultured endothelial cells in a microfluidic channel significantly accelerated the rate of thrombus formation under arterial flow. Our results demonstrate for the first time a potential role of measuring plasma bigET-1 in patients with acute iTTP in assessing the disease severity and risk of in-hospital mortality, which may help stratify patients for a more aggressive monitoring and therapeutic strategy; also, the bioactive ET-1, derived from bigET-1, may result in acute renal injury in TTP patient, likely through its vasoconstriction and prothrombotic properties.

T-follicular helper cell expansion and chronic T-cell activation are characteristic immune anomalies in Evans syndrome.

Pediatric Evans syndrome (pES) is increasingly identified as the presenting manifestation of several inborn errors of immunity. Despite an improved understanding of genetic defects in pES, the underlying immunobiology of pES is poorly defined, and characteristic diagnostic immune parameters are lacking. We describe the immune characteristics of 24 patients with pES and compared them with 22 patients with chronic immune thrombocytopenia (cITP) and 24 healthy controls (HCs). Compared with patients with cITP and HC, patients with pES had increased circulating T-follicular helper cells (cTfh), increased T-cell activation, and decreased naïve CD4+ T cells for age. Despite normal or high immunoglobulin G (IgG) in most pES at presentation, class-switched memory B cells were decreased. Within the cTfh subset, we noted features of postactivation exhaustion with upregulation of several canonical checkpoint inhibitors. T-cell receptor ß chain (TCR-ß) repertoire analysis of cTfh cells revealed increased oligoclonality in patients with pES compared with HCs. Among patients with pES, those without a known gene defect had a similar characteristic immune abnormality as patients with defined genetic defects. Similarly, patients with pES with normal IgG had similar T-cell abnormalities as patients with low IgG. Because genetic defects have been identified in less than half of patients with pES, our findings of similar immune abnormalities across all patients with pES help establish a common characteristic immunopathology in pES, irrespective of the underlying genetic etiology.

Could Antinuclear Antibody Positivity Be a Factor Affecting Treatment Response in Immune Thrombocytopenia Patients on Eltrombopag?

Objective: Eltrombopag remains a prominent option in the treatment of steroid-dependent or steroid-refractory immune thrombocytopenia (ITP) patients. Unfortunately, not all patients respond to eltrombopag. Antinuclear antibody (ANA) positivity can be seen at rates of up to 30% in ITP patients. Despite being widely used, more markers to predict the response to eltrombopag are still needed. In the present study, we aimed to show the association between ANA positivity and eltrombopag response in ITP patients. Materials and Methods: Patients who were diagnosed with ITP in the Trakya University Faculty of Medicine's Department of Hematology and who underwent eltrombopag treatment due to their resistance to steroids and other treatments were included in our study. ANA measurement was performed by indirect fluorescent antibody method and titers of 1:160 and above were considered positive. ANA measurements were made before starting eltrombopag. Results: Forty-five patients were included in our study, 33 being women and 12 men. The mean age of the patients was 45.73 years. There were 14 patients with ANA positivity and 31 patients were found to be ANA-negative. Response rates were higher in ANA-negative patients compared to ANA-positive patients in the 1st and 6th months of eltrombopag treatment (p<0.05). Conclusion: ANA positivity in ITP may indicate unresponsiveness to eltrombopag treatment, a finding that should be further supported by prospective studies involving more patients.

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.

Gout-like hands.

A 65-year-old man presented to our hospital with a 1-year history of multiple nodules on his arms and hands without itching or pain.

Immune Status and Chemokine C Receptor 7 Expression in Primary in Patients with Immune Thrombocytopenia

Objective: The present study investigated immune disorders and chemokine C receptor 7 (CCR7) expression in primary immune thrombocytopenia (ITP) patients and analyzed their changes and clinical significance before and after treatments. Materials and Methods: Flow cytometry was used to detect the proportion of different immune cell subsets in the peripheral blood of 42 patients with ITP and 20 healthy controls at different time points. Treatments included first-line drugs, such as glucocorticoids and intravenous immunoglobulin, and second-line therapy, such as interleukin-11 and thrombopoietin receptor agonists. Results: An elevated CD4/CD8 ratio and decreased natural killer (NK) cells and CD4+CD25+CD127low regulatory T-cells (Tregs) were found in pretreatment ITP patients compared to healthy controls. The newly diagnosed group had a higher CD4/CD8 ratio and more NK cells than the relapsed group. Treg levels of the remission group were higher than those of the recurrence group. The CD4+CCR7+, CD8+CCR7+, and CCR7+ subsets of B cells and NK cells showed higher increases in the newly diagnosed and relapsed group compared to controls and the remission group. The values for the CD4+CCR7+ and CD8+CCR7+ subsets in the relapsed group were slightly higher than those in the newly diagnosed group. The CCR7+ subsets of CD4+ T-cells, CD8+ T-cells, NK cells, and B cells had lower values in the remission group compared to the relapsed group. Higher levels of the CD8+CCR7+ subset and lower levels of NK cells were found in the remission group compared to the controls. The ratio between the CD4+CCR7+ subset and CD8+CCR7+ subset was lower in ITP patients than in healthy controls. There was a negative correlation between the CD8+CCR7+ subset and platelet count in the ITP patients. Conclusion: ITP patients with CCR7 had immune disorders and high heterogeneity, and CCR7 was found to be involved in the pathogenesis of ITP. Further studies are needed to investigate effective treatments for ITP by targeted regulation of CCR7.