Objective To evaluate whether Vibrio vulnificus secreted exotoxin-hemolysin (VVH) can activate platelet, an important blood immune cell, and to explore the possible molecular mechanism of platelet activation by VVH. Methods Transcriptomics and immunohistochemistry were used to analyze whether Vibrio vulnificus infection caused platelet activation in mice. Then, flow cytometry was used to identify whether VVH was the main stimulator of platelet activation. Naturally expressed VVH toxin was purified and prepared. The effects of extracellular and intracellular Ca²⁺ signal inhibitors on VVH activated platelets were evaluated by flow cytometry and Western blotting. The immune activation effect of VVH in the early stage of Vibrio vulnificus infection was analyzed in vivo. Results VVH was the main stimulator of platelet activation in Vibrio vulnificus culture supernatant. Natural VVH can induce the increase of P-selectin (CD62P) on platelet surface, the formation of platelet-neutrophil complex (PNC), and the release of platelet microvesicles. The activation mechanism may be related to the VVH pore-dependent Ca²⁺-calmodulin (CaM) -myosin light chain kinase (MLCK) signaling pathway, which led to the release of platelet alpha particles and cascade activation of platelets. In a mouse model of ALD infected by Vibrio vulnificus gavage, VVH was strongly associated with platelet activation. Conclusion This study shows that VVH is an important platelet activating molecule in the early stage of Vibrio vulnificus infection, and its induction of platelet activation may be related to the pathogenic process.
Animals ; Platelet Activation/drug effects* ; Hemolysin Proteins/pharmacology* ; Vibrio vulnificus/metabolism* ; Mice ; Blood Platelets/drug effects* ; Vibrio Infections/immunology* ; P-Selectin/metabolism* ; Bacterial Proteins ; Female

Objective To analyze the distribution of platelet antibodies in hospitalized patients and explore the clinical significance of platelet antibody detection. Methods A total of 95 987 hospitalized patient cases from a tertiary hospital in Xi'an from April 1, 2021 to December 31, 2023 were collected. Platelet antibodies were detected by solid-phase agglutination method. Statistical analysis was performed on variables including gender, age, blood type, department, history of blood transfusion, pregnancy history, and disease type. Results Among 95 987 hospitalized patients, the positive rate of platelet antibody detection reached 4.35%. The positive rate of platelet antibodies in female hospitalized patients (5.29%) was higher than that in male patients (3.31%), and the difference was statistically significant (x²=224.124). The positive rate of platelet antibodies in those with pregnancy history (7.92%) was higher than that in those without pregnancy history (4.19%), and the difference was significant (x²=292.773). Similarly, the positive rate of platelet antibodies in those with transfusion history (7.79%) was higher than that in those without transfusion history (3.97%), and the difference was significant (x²=300.209). There was a significant correlation between the positive rate of platelet antibodies and the number of pregnancies (x²=91.061). Conclusion The positive rate of platelet antibodies in 95 987 inpatient cases was 4.35%. The positive rate of platelet antibodies had a close relationship with a history of blood transfusions and pregnancies, and it increased with the number of pregnancies. For patients with multiple transfusion histories and pregnancy histories, screening for platelet antibodies holds significant diagnostic value.
Humans ; Female ; Male ; Adult ; Middle Aged ; Blood Platelets/immunology* ; Inpatients ; Aged ; Pregnancy ; Young Adult ; Adolescent ; Aged, 80 and over ; Autoantibodies/blood*

Objective To investigate the therapeutic efficacy of HLA-genotype matched platelet transfusion using a platelet donor database for severe platelet transfusion refractoriness (PTR) caused by HLA antigen-antibody incompatibility. Methods Using real-time quantitative PCR (qPCR) to identify he patient's HLA class I genotype, followed by searching the platelet donor database for matching donors, and selecting highly compatible donors for transfusion. Platelets with higher compatibility levels were prioritized for transfusion recommendations. Results Among the 19 patients studied, 7 patients identified donors with B2U or higher compatibility, 6 patients identified donors with BX or higher compatibility, and 6 patients did not find a suitable donor. The transfusion efficacy was evaluated by calculating the corrected count increment (CCI) 24 hours post-transfusion, and all transfusions were effective. Conclusion The optimal strategy to prevent and treat patients with severe platelet transfusion refractoriness is to ensure patients receive platelet transfusions that are matched to their HLA genes, and this approach significantly enhances transfusion efficacy.
Humans ; Platelet Transfusion/adverse effects* ; HLA Antigens/immunology* ; Male ; Middle Aged ; Female ; Adult ; Blood Platelets/immunology* ; Aged ; Genotype

OBJECTIVE: To investigate the correlation between platelet alloantibodies and CD8⁺ T cell with platelet desialylation and apoptosis in platelet transfusion refractoriness(PTR). METHODS: The expression of RCA-1, CD62P and Neu1 on platelets were detected in 135 PTR patients and 260 healthy controls. The ability of PTR patients' sera with anti-HLA antibody, anti-CD36 antibody and antibody-negative groups to induce platelet desialylation and apoptosis, and the potential effect of FcγR inhibitors on desialylation and apoptosis were evaluated. Additionally, the association between CD8⁺ T cells and platelet desialylation in patients was analyzed. RESULTS: The expression of RCA-1 and Neu1 on platelets in PTR patients were significantly higher than those in healthy donors（P < 0.05）, but were not related to platelet alloantibody (P >0.05). The sera of PTR patients generally induced platelet desialylation in vitro （P < 0.05）, with no significant differences among the groups（P >0.05）. However, the sera with anti-CD36 antibodies could induce platelet apoptosis significantly higher than that in the anti-HLA antibody group and antibody-negative group in vitro (P < 0.05). In PTR patients with anti-CD36 antibodies, platelet apoptosis was dependent on FcγR signaling, while desialylation is not. Moreover, CD8⁺ T cells in PTR patients were significantly associated with platelet desialylation (P < 0.05). CONCLUSION Platelet desialylation is a common pathological phenomenon in PTR patients， which involves the participation of CD8⁺ T cell, but isn't associated with platelet alloantibody; while anti-CD36 antibodies have potential clinical significance in predicting platelet apoptosis in PTR patients.
Humans ; Apoptosis ; CD8-Positive T-Lymphocytes/immunology* ; Blood Platelets/metabolism* ; Platelet Transfusion ; Isoantibodies ; Male ; Female ; Middle Aged

Hypoxemia is a common pathological state characterized by low oxygen saturation in the blood. This condition compromises mucosal barrier integrity particularly in the gut and oral cavity. However, the mechanisms underlying this association remain unclear. This study used periodontitis as a model to investigate the role of platelet activation in oral mucosal immunopathology under hypoxic conditions. Hypoxia upregulated methyltransferase-like protein 4 (METTL4) expression in platelets, resulting in N⁶-methyladenine modification of mitochondrial DNA (mtDNA). This modification impaired mitochondrial transcriptional factor A-dependent cytosolic mtDNA degradation, leading to cytosolic mtDNA accumulation. Excess cytosolic mt-DNA aberrantly activated the cGAS-STING pathway in platelets. This resulted in excessive platelet activation and neutrophil extracellular trap formation that ultimately exacerbated periodontitis. Targeting platelet METTL4 and its downstream pathways offers a potential strategy for managing oral mucosa immunopathology. Further research is needed to examine its broader implications for mucosal inflammation under hypoxic conditions.
DNA, Mitochondrial/metabolism* ; Mouth Mucosa/pathology* ; Hypoxia/immunology* ; Methyltransferases/metabolism* ; Blood Platelets/metabolism* ; Animals ; Periodontitis/immunology* ; Humans ; Platelet Activation ; Mice

Megakaryocytes (MKs), which are traditionally known for their role in platelet production, are now emerging as unique immune cells with diverse capabilities. They express immune receptors, participate in pathogen recognition and response, phagocytose pathogens, contribute to antigen presentation, and interact with various immune cell types. When encountering inflammatory challenges, MKs exhibit intricate immune functions that can either promote or inhibit inflammation. These responses are mediated through mechanisms, such as the secretion of either anti-inflammatory or pro-inflammatory cytokines and release of immunomodulatory platelets according to specific conditions. This intricate array of responses necessitates a detailed exploration to determine whether the immune functions of MKs are carried out by the entire MK population or by a specific subpopulation. Breakthroughs in single-cell RNA sequencing have uncovered a unique "immune MK" subpopulation, revealing its distinct characteristics and immunoregulatory functions. This review provides latest insights into MKs' immune attributes and their roles in physiological and pathological contexts and emphasizes the discovery and functions of "immune MKs".
Animals ; Humans ; Blood Platelets/immunology* ; Cytokines/metabolism* ; Inflammation/immunology* ; Megakaryocytes/metabolism*

Gastric cancer (GC) is one of the most common tumor in the world, and remains a major public health problem and one of the leading causes of death. Recently many researches have demonstrated that systemic inflammatory response is associated with prognosis and response to therapy in gastric cancer, and the peripheral blood count test can partly reflect the systemic inflammatory response. Based on the peripheral blood count test, there are a lot of research regarding the relation between the platelet count (PLT), neutrophil, lymphocyte, white blood cell (WBC), neutrophil to lymphocyte ratio(NLR), platelet to lymphocyte ratio (PLR) with their prognostic role in gastric cancer. A high PLT and preoperative lymphocytopenia are both associated with increased lymph node metastasis, stage (III(+IIII(), serosal invasion (T3+T4) risk and poorer overall survival. Besides above, platelet monitoring following surgery can be applied to predict the recurrence for patients with GC that suffer preoperative high PLT but have restored PLT levels following resection. Moreover systemic inflammatory factors based on blood parameters, such as PLR, NLR and so on, have relation with the poor prognosis of patients with GC. Among them, high NLR is a negative predictor of prognosis in GC patients. However PLR remains inconsistent, while most researches demonstrated high PLR may be useful prognostic factor rather than independent prognostic factor. There are still some limitations which include various cut-off values, little of clinician attention, the uncertain mechanism, etc. Here we review the research progress in the prognostic role of the blood count test in gastric cancer.
Blood Cell Count ; methods ; statistics & numerical data ; Blood Platelets ; physiology ; Humans ; Inflammation ; blood ; diagnosis ; immunology ; Leukocyte Count ; statistics & numerical data ; Lymphatic Metastasis ; diagnosis ; immunology ; Lymphocyte Count ; statistics & numerical data ; Lymphopenia ; blood ; physiopathology ; Neoplasm Invasiveness ; immunology ; Neoplasm Recurrence, Local ; blood ; diagnosis ; Neoplasm Staging ; statistics & numerical data ; Neutrophils ; immunology ; Platelet Count ; statistics & numerical data ; Prognosis ; Stomach Neoplasms ; blood ; diagnosis ; immunology ; mortality ; Treatment Outcome

OBJECTIVETo detect platelet anti-HPA-1a and -1b antibodies using recombinant GPIIIa fragments coupled to Luminex beads.

METHODSThe sensitivity of 2 techniques, monoclonal antibody specific immobilization of platelet antigen (MAIPA) and Luminex bead assay, was compared using 12 twofold-serial dilutions (from neat to 1 in 2048) of an anti-HPA-1a WHO international standard. The specificity of Luminex assay to identify anti-HPA-1a and -1b antibodies was assessed using 8 negative or positive controls and 36 blinded samples provided by WHO Platelet Workshop.

RESULTSThe sensitivity of MAIPA and Luminex bead assay to detect anti-HPA-1a was dilution 1/64 (i.e. 1.56 IU/ml) and far more than dilution 1/2048 (i.e. 0.049 IU/mL), respectively. The Luminex bead assay could specifically identify negative and positive controls of anti-HPA-1a and -1b. All results of 36 blinded samples by Luminex assay were accordant to reference results except one sample which contained high concentration antithetical antibody and resulted in false positive of anti-HPA-1b. Cross-reactivity was also not observed with the samples containing HLA, ABO or other platelet antibodies.

CONCLUSIONThe Luminex beads coupled with recombinant GPIIIa fragments can be used to detect HPA-1 system antibodies with sufficient sensitivity and specificity, that is suitable for the detection of platelet alloantibodies in clinical alloimmune thrombocytopenia.

Antibodies, Monoclonal ; Antigens, Human Platelet ; immunology ; Blood Platelets ; Humans ; Integrin beta3 ; chemistry ; Isoantibodies ; blood ; Purpura, Thrombocytopenic, Idiopathic ; diagnosis ; Recombinant Proteins ; chemistry ; Sensitivity and Specificity

OBJECTIVETo investigate the influence of divalent cation chelator EDTA and heparin sodium on the detection of ITP platelet-specific autoantibodies by the modified monoclonal antibody immobilization of platelet antigen assay (MAIPA) and to explore the relationship between types of platelet specific autoantibodies and glucocorticoid efficacy.

METHODSThe samples were obtained from EDTA- and heparin- anticoagulant ITP patients, respectively, so as to detect the platelet-specific autoantibodies (GPIIb/IIIa and GPIbα) in 140 ITP samples by modified MAIPA, then the differences between these two methods were compared.

RESULTSOut of 140 cases in EDTA group, 55 cases were positive for GPIIb/IIIa, while 76 cases in heparin group were positive for GPIIb/IIIa, 42 cases in both group were repeatable; among them 13 cases were positive in EDTA group and negative in heparin group, while 34 cases were positive in heparin group and negative in EDTA group, there was significant difference between them (x (2) = 9.38, P < 0.05), 62 cases in 140 cases of EDTA group were positive for GPIba, while 51 cases in heparin group were positive for GPIba, 42 cases in both group were repeatabe; among them 20 cases were positive in EDTA group and negative in heparin group, while 9 cases were positive in heparin group and negative in EDTA group, there was no significant difference between them (x (2) = 3.44, P > 0.05). A total of 320 cases received a standard glucocorticoid treatment, out of them 143 cases were positive for GPIbα with effective rate 39.9%, 177 cases were negative for GPIbα with effective rate 79.7%, there was statisticalty significant difference between them (x (2) = 53.115, P < 0.05).

CONCLUSIONEDTA anticoagulant (a divalent cation chelator) has a significant influence on detection of ITP platelet-specific autoantibodies (GPIIb/IIIa) by a modified MAIPA method and the GPIbα antibody positive may be one of the important factors that results in un-sensitivity of ITP patients to glucocorticoid treatment.

Antibodies, Monoclonal ; Anticoagulants ; therapeutic use ; Antigens, Human Platelet ; Autoantibodies ; blood ; Blood Platelets ; immunology ; Fibrinolytic Agents ; Glucocorticoids ; therapeutic use ; Heparin ; Humans ; Platelet Glycoprotein GPIIb-IIIa Complex ; Purpura, Thrombocytopenic, Idiopathic ; blood ; immunology

Immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease. It is considered that production of platelet auto-antibodies was one of the pathogenesis of ITP, first-line therapy including corticosteroid and immunoglobulin could reduce destruction of platelets by inhibiting production of auto-antibodies and blocking Fc-receptor of reticuloendothelial system, but some of the patients were refractory to first-line therapy and have persistent duration of the disease, having worse prognosis and developing into chronic/refractory ITP(C/RITP) . Platelet membrane glycoprotein like GPIIb/IIIa and GPIbα are the most common antigen targets, but first-line therapy was less effective to patients whose anti-GPIbα antibodies are positive. Further studies revealed that the way causing platelet destruction by anti-GPIIb/IIIa antibodies and anti-GPIbα antibodies are different: the former is mainly dependent to Fc-pathway, and the latter mainly cleared platelet by Fc-independent way. Results above indicated that detection of type of platelet auto-antibodies maybe potential to treatment and prognosis of ITP. This article summarizes relationship between platelet specific antibodies and the onset, clinical manifestation, treatment and prognosis of ITP.
Antibodies ; immunology ; Autoimmune Diseases ; Blood Platelets ; immunology ; Humans ; Platelet Membrane Glycoproteins ; Prognosis ; Thrombocytopenia ; immunology ; therapy