Effect of steroids on the activation status of platelets in patients with Immune thrombocytopenia (ITP)

Glucagon-like Peptide-1 Receptor Pathway Attenuates Platelet Activation in Aspirin-Exacerbated Respiratory Disease

Platelets are key contributors to allergic asthma and aspirin-exacerbated respiratory disease (AERD), an asthma phenotype involving platelet activation and IL-33-dependent mast cell activation. Human platelets express the glucagon-like peptide-1 receptor (GLP-1R). GLP-1R agonists decrease lung IL-33 release and airway hyperresponsiveness in mouse asthma models. We hypothesized that GLP-1R agonists reduce platelet activation and downstream platelet-mediated airway inflammation in AERD. GLP-1R expression on murine platelets was assessed using flow cytometry. We tested the effect of the GLP-1R agonist liraglutide on lysine-aspirin (Lys-ASA)-induced changes in airway resistance, and platelet-derived mediator release in a murine AERD model. We conducted a prospective cohort study comparing the effect of pretreatment with liraglutide or vehicle on thromboxane receptor agonist-induced in vitro activation of platelets from patients with AERD and nonasthmatic controls. GLP-1R expression was higher on murine platelets than on leukocytes. A single dose of liraglutide inhibited Lys-ASA-induced increases in airway resistance and decreased markers of platelet activation and recruitment to the lung in AERD-like mice. Liraglutide attenuated thromboxane receptor agonist-induced activation as measured by CXCL7 release in plasma from patients with AERD and CD62P expression in platelets from both patients with AERD (n = 31) and nonasthmatic, healthy controls (n = 11). Liraglutide, a Food and Drug Administration-approved GLP-1R agonist for treatment of type 2 diabetes and obesity, attenuates in vivo platelet activation in an AERD murine model and in vitro activation in human platelets in patients with and without AERD. These data advance the GLP-1R axis as a new target for platelet-mediated inflammation warranting further study in asthma.

In vivo ameliorative effects of vitamin E against hydralazine-induced lupus

OBJECTIVE

In this study, we investigated the in vivo ameliorative effects of vitamin E in a hydralazine-induced lupus model, which closely resembles SLE in humans. We aim to shed light on its potential as a therapeutic agent for managing SLE.

METHODS

Forty BALB/c mice were used in this study. Hydralazine hydrochloride was orally administered in a concentration of 25 mg/kg to the five mice groups once weekly for a period of 5 weeks to induce a lupus-like condition. The untreated group was the normal control group. To confirm the development of lupus, an ANA test was conducted. After the mice tested positive for ANA, drug treatments commenced. The negative control group did not receive any drug treatment. The treatments included prednisolone, methotrexate and vitamin E, all administered at a concentration of 25 mg/kg, with a higher dose of vitamin E (50 mg/kg) also administered.

RESULTS

Notably, on day 35, after drug treatment, we observed that mice that received vitamin E at a dosage of 50 mg/kg (3.01±0.100) had a slight decrease in lymphocyte hydrogen peroxide radicals when compared with the group receiving 25 mg/kg of vitamin E (3.30±0.100) (p<0.05). This finding suggests that the scavenging potential of vitamin E is dose dependent.

CONCLUSION

This study suggests that vitamin E supplementation, especially at a higher dose (50 mg/kg), holds promise in ameliorating lupus-like conditions. These findings warrant further exploration and may offer a potential avenue for improving the disease status of patients experiencing SLE.

Chronic Immune Platelet Activation Is Followed by Platelet Refractoriness and Impaired Contractility

Autoimmune diseases, including systemic lupus erythematosus (SLE), have a high risk of thrombotic and hemorrhagic complications associated with altered platelet functionality. We studied platelets from the blood of SLE patients and their reactivity. The surface expression of phosphatidylserine, P-selectin, and active integrin αIIbβ3 were measured using flow cytometry before and after platelet stimulation. Soluble P-selectin was measured in plasma. The kinetics of platelet-driven clot contraction was studied, as well as scanning and transmission electron microscopy of unstimulated platelets. Elevated levels of membrane-associated phosphatidylserine and platelet-attached and soluble P-selectin correlated directly with the titers of IgG, anti-dsDNA-antibodies, and circulating immune complexes. Morphologically, platelets in SLE lost their resting discoid shape, formed membrane protrusions and aggregates, and had a rough plasma membrane. The signs of platelet activation were associated paradoxically with reduced reactivity to a physiological stimulus and impaired contractility that revealed platelet exhaustion and refractoriness. Platelet activation has multiple pro-coagulant effects, and the inability to fully contract (retract) blood clots can be either a hemorrhagic or pro-thrombotic mechanism related to altered clot permeability, sensitivity of clots to fibrinolysis, obstructiveness, and embologenicity. Therefore, chronic immune platelet activation followed by secondary platelet dysfunction comprise an understudied pathogenic mechanism that supports hemostatic disorders in autoimmune diseases, such as SLE.

Massive Spontaneous Suprachoroidal Hemorrhage in a Patient With Type 1 Chronic Myeloid Leukemia and Lymphoplasmacytic Lymphoma: Case Report and Review of the Literature

Purpose:

This work reports a rare case of spontaneous suprachoroidal hemorrhage (SSCH) and summarizes the literature on its treatment options and outcomes.

Methods:

A case report and comprehensive literature review are presented on the medical and surgical management of SSCH on PubMed from 1998 to 2021.

Results:

The literature search revealed 58 studies, 33 of which included 52 eyes of 47 patients. Surgical treatment typically consisted of choroidal drainage with posterior sclerotomies combined with pars plana vitrectomy and silicone oil placement. Medical therapy involved intraocular pressure control with laser peripheral iridotomy and topical, oral, and intravenous medication.

Conclusions:

In cases of SSCH, conservative management and a prompt workup should be initiated to identify the cause before proceeding with surgery. If the initial workup does not reveal a cause, medical and surgical treatments are both viable and the decision is at the discretion of the treating physician.

Role of neutrophils, platelets, and extracellular vesicles and their interactions in COVID-19-associated thrombopathy

The COVID-19 pandemic extended all around the world causing millions of deaths. In addition to acute respiratory distress syndrome, many patients with severe COVID-19 develop thromboembolic complications associated to multiorgan failure and death. Here, we review evidence for the contribution of neutrophils, platelets, and extracellular vesicles (EVs) to the thromboinflammatory process in COVID-19. We discuss how the immune system, influenced by pro-inflammatory molecules, EVs, and neutrophil extracellular traps (NETs), can be caught out in patients with severe outcomes. We highlight how the deficient regulation of the innate immune system favors platelet activation and induces a vicious cycle amplifying an immunothrombogenic environment associated with platelet/NET interactions. In light of these considerations, we discuss potential therapeutic strategies underlining the modulation of purinergic signaling as an interesting target.

Hypoplastic acute myeloid leukemia in an elderly patient. A long-term partial remission with low-dose prednisone and G-CSF

Hypoplastic acute myeloid leukemia (AML) is a rare variant of AML that mainly affects the elderly and accounts for 5%-7% of de novo AML. Prognosis for this disease is poor, and there is no standard therapy. We have treated an elderly patient with hypoplastic AML with low-dose prednisone and G-CSF with good results. We propose that this treatment may be a viable alternative to supportive therapy alone, or the tenuous chemotherapeutic challenge to elderly patients with hypoplastic AML.

Drug-induced activation of integrin alpha IIb beta 3 leads to minor localized structural changes

Integrins are transmembrane proteins involved in hemostasis, wound healing, immunity and cancer. In response to intracellular signals and ligand binding, integrins adopt different conformations: the bent (resting) form; the intermediate extended form; and the ligand-occupied active form. An integrin undergoing such conformational dynamics is the heterodimeric platelet receptor αIIbβ3. Although the dramatic rearrangement of the overall structure of αIIbβ3 during the activation process is potentially related to changes in the protein secondary structure, this has not been investigated so far in a membrane environment. Here we examine the Mn2+- and drug-induced activation of αIIbβ3 and the impact on the structure of this protein reconstituted into liposomes. By quartz crystal microbalance with dissipation monitoring and activation assays we show that Mn2+ induces binding of the conformation-specific antibody PAC-1, which only recognizes the extended, active integrin. Circular dichroism spectroscopy reveals, however, that Mn2+-treatment does not induce major secondary structural changes of αIIbβ3. Similarly, we found that treatment with clinically relevant drugs (e.g. quinine) led to the activation of αIIbβ3 without significant changes in protein secondary structure. Molecular dynamics simulation studies revealed minor local changes in the beta-sheet probability of several extracellular domains of the integrin. Our experimental setup represents a new approach to study transmembrane proteins, especially integrins, in a membrane environment and opens a new way for testing drug binding to integrins under clinically relevant conditions.

A characteristic flow cytometric pattern with broad forward scatter and narrowed side scatter helps diagnose immune thrombocytopenia (ITP)

Various disorders cause severe thrombocytopenia, which can lead to critical hemorrhage. Procedures that rapidly support the diagnosis and risk factors for serious bleeding were explored, with a focus on immune thrombocytopenia (ITP). Twenty-five patients with thrombocytopenia, including 13 with newly diagnosed ITP, 3 with chronic ITP, 6 with aplastic anemia (AA), and 3 with other thrombocytopenia (one acute myeloid leukemia, one acute lymphoblastic leukemia, and one hemophagocytic lymphohistiocytosis), were reviewed. In addition to platelet-related parameters obtained by an automated hematology analyzer, flow cytometric analysis of platelets was performed. A characteristic flow cytometric pattern with broad forward scatter and narrowed side scatter, which is specific to ITP, but not other types of thrombocytopenia, was found. CD62P-positive platelets were increased in newly diagnosed ITP cases compared to control (P < 0.0001), AA (P = 0.0032). Moreover, detection of dramatic changes in these parameters on sequential monitoring may suggest internal hemorrhage, even absent skin or visible mucosal bleeding. The bleeding score for visible mucosae had a negative correlation with platelet count and a positive correlation with immature platelet fraction (%), forward scatter, and CD62P. This characteristic flow cytometric pattern makes it possible to distinguish ITP from other thrombocytopenic disorders.

Utility of Mean Platelet Volume to Diagnose Pneumonia in Patients With Solid-Organ Transplant

OBJECTIVES

Despite improved success with solid-organ transplant procedures, recipients remain at risk for infections, including pneumonia, due to their immunosuppressive regimens. In solid-organ transplant patients, clinical findings of pneumonia can be nonspecific, and diagnosis of pneumonia may be difficult as several conditions (drug lung, hypervolemia, infections, hemorrhage) can led to pulmonary infiltrates, mimicking pneumonia in these patients. The role of mean platelet volume, a predictor of inflammatory disease, with elevated values inversely correlated with inflammatory problems, in the diagnosis of pneumonia has not yet been investigated in solid-organ transplant patients. Here, we retrospectively investigated mean platelet volume in diagnosis of pneumonia in transplant patients.

MATERIALS AND METHODS

Medical records of solid-organ transplant patients from 2011 to 2016 were reviewed for demographic, clinical, radiographic, laboratory, and microbiology data. Transplant type, immunosuppressive drugs, and clinical outcomes were noted. Pneumonia diagnosis was based on clinical respiratory symptoms and signs, imaging findings, positive microbiological tests, pathologic findings, laboratory findings, or effective clinical treatment trials.

RESULTS

Our study included 70 patients (47 male/23 female; mean age of 46 ± 14 years), comprising 26 liver and 44 renal transplant recipients. Pneumonia was diagnosed radiologically in 30 patients (42.9%), with procalcitonin positive in 11 patients (36.7%), C-reactive protein elevated in 29 patients (96.7%), and leukocytes increased in 6 patients (20%). When laboratory measurements were compared with mean platelet volume, mean platelet volume values were significantly lower in patients with pneumonia who had elevated procalcitonin levels (P = .038).

CONCLUSIONS

We found that mean platelet volume for diagnosis of pneumonia in solid-organ transplant patients was not a promising tool. Considering the difficulties in caring for transplant patients with pulmonary infiltrates, clinical decisions should be based on clinical, laboratory, microbiological, and radiologic findings.

[Relative analysis of platelet activation with bleeding risk in patients with primary immune thrombocytopenia]

Objective: To study the relationship between platelet activation and the degree of bleeding in patients with primary immune thrombocytopenia (ITP) . Methods: 43 patients with ITP were assessed based on ITP-BAT bleeding grading system. Platelet membrane glycoproteins (GP) Ⅰb, GPⅡb/Ⅲa and P-selectin expression were detected by flow cytometry analysis with and without adenosine diphosphate (ADP) stimulation. Association of platelet activation with platelet count, immature platelet fraction (IPF) , bleeding severity were evaluated. Results: GPⅡb/Ⅲa and P-selection expressions on unstimulated platelet in ITP patients were higher than those in healthy controls (65.69±10.73 vs 7.16±0.99, t=4.130, P<0.001; 15.43±1.41 vs 12.55±1.03, t=2.070, P=0.043, respectively) , and GPⅠb expression was lower than that in healthy controls (240.11±24.93 vs 295.11±22.15, t=2.417, P=0.020) . Comparatively to healthy individuals, following ADP stimulation, GPⅡb/Ⅲa expression in ITP patients increased (133.96±12.17 vs 39.67±4.99, t=5.256, P<0.001) , whereas GPⅠb and P-selection expressions decreased (37.09±3.94 vs 109.77±23.66, t=3.901, P<0.001; 149.06±19.14 vs 205.73±21.00, t=2.070, P=0.043, respectively) . ADP-stimulated GPⅠb, ADP-stimulated and unstimulated P-selection, proportion of GPⅠb, P-selection levels with/without ADP stimulation were significantly associated with platelet counts (P<0.05) . ADP-stimulated P-selection and proportion of P-selection levels with/without ADP stimulation were significantly associated with IPF (P<0.05) . There were significant differences in the expressions of unstimulated P-selection, ADP-stimulated P-selection, ADP-stimulated GPⅠb stratified by bleeding grades (P<0.05) . The ratios of P-selection, GPⅡb/Ⅲa and GPⅠb with/without ADP stimulation in ITP patients were significantly different among various bleeding grades (P<0.05) . Higher proportion of GPⅠb with/without ADP stimulation was associated with higher risk of bleeding (OR=3.05, P=0.011) . Lower proportion of GPⅡb/Ⅲa and P-selection with/without ADP was associated with higher risk of bleeding (OR=0.32, P=0.023; OR=0.04, P=0.006, respectively) . Conclusion: Platelet activation index could accurately assess the degree of bleeding in patients with ITP, and also be used as the observation index and reference index for treatment.

Role of platelet function and platelet membrane glycoproteins in children with primary immune thrombocytopenia

The aim of the present study was to examine and understand changes in platelet functions prior to and after the treatment of primary immune thrombocytopenia (ITP) in children. An automatic hematology analyzer and whole blood flow cytometry were used to detect immature platelet fraction (IPF), IPC and membrane glycoproteins (CD62p, PAC-1 and CD42b) in ITP children (ITP group), children with complete response after ITP treatment (ITP-CR group) and children with elective surgery (normal control group). The results showed that, levels of platelet count (PLT) and plateletcrit in the ITP group were lower alhtough the levels of mean platelet volume, platelet distribution width and platelet-large cell ratio (P-LCR) were higher than those in the normal control and ITP-CR groups. PLT in the ITP-CR group was lower than that in the normal controls. Additionally, IPF% was higher in the normal control and ITP-CR groups, IPC was lower in the ITP group compared to the normal control and ITP-CR groups. Furthermore, prior to ADP activation, the expression levels of CD62p, PAC-1 and CD42b in the ITP group were lower in ITP group than those in the normal control and ITP-CR groups. The expression level of PAC-1 was lower in the ITP-CR and normal control groups. No differences were identified in CD62p and CD42b expression levels. Following ATP activation, CD62p, PAC-1 and CD42b expression in the ITP group was lower than that in the normal control and ITP-CR groups. PAC-1 expression was lower while CD62p expression was higher in the ITP-CR group compared to the normal control group. In conclusion, the activation of platelets in ITP children was low. Decreased platelet function, platelet parameters and platelet glycoproteins may be used as markers for monitoring the treatment efficacy in ITP children.

Immunodiagnosis of platelet activation in immune thrombocytopenia through scFv antibodies cognate to activated IIb3 integrins

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by low platelet count and presence of IgG autoantibodies to platelet surface glycoproteins, such as α IIbβ3 and GPIb/IX. Our previous work has shown that platelets in ITP patients exist in an activated state. Two different marker-based approaches are used to study the course of platelet activation: (1) binding of PAC-1 antibody, signifying a change in αIIbβ3 conformation, and (2) expression of P-selectin, signifying alpha granule content release from platelets. Here, we describe the development of a new scFv antibody (R38) that, compared with PAC-1, appears to better distinguish between platelets of ITP patients and healthy controls. Notably, R38 was generated using commercially sourced resting-state integrin that was coated on a microtiter plate. Its ability to distinguish between ITP patients and healthy controls thus suggests that inadvertent integrin activation caused by coating involves a conformational change and exposure of a cryptic epitope. This report also describes for the first time the potential use of an scFv antibody in the immunodiagnosis of platelet activation in ITP patients.