A role of platelet C-type lectin-like receptor-2 and its ligand podoplanin in vascular biology.

PURPOSE OF REVIEW: Platelets are essential for hemostasis and are also vital in lymphatic and lung development and the maintenance of vascular integrity. Platelet activation receptor C-type lectin-like receptor 2 (CLEC-2) and its endogenous ligand podoplanin (PDPN) in lymphatic endothelial cells (LECs) and other cells regulate these processes. This review aims to comprehensively summarize the roles of platelet CLEC-2 and PDPN. This review also focuses on discussing the underlying mechanisms by which platelet CLEC-2 and PDPN mediate blood/lymphatic separation. FINDINGS: CLEC-2/PDPN-induced platelet activation in the primary lymph sacs, developmental lymphovenous junctions, neonatal mesentery, and the site of tumor lymphangiogenesis prevents blood/lymphatic vessel misconnection. Further, CLEC-2/PDPN-induced platelet activation is essential for lung development. Mice deficient in CLEC-2 or PDPN show blood-filled lymphatics, lung malformations, and cerebrovascular abnormalities. CLEC-2 deletion in steady-state adult mice did not result in blood/lymphatic vessel mixing. In adulthood, CLEC-2 maintains vascular integrity and that of high endothelial venules in lymph nodes. CLEC-2 deletion in adulthood results in hemorrhage under inflammatory conditions, and hemolymph nodes. SUMMARY: The platelet CLEC-2/LEC PDPN interaction prevents blood/lymphatic vessel mixing at active remodeling sites of the blood/lymphatic system, but not in steady-state adult mice. This interaction also regulates vascular integrity when vascular permeability increases before and after birth.

Abnormalities in C-type lectin-like receptor 2 in a patient with Gorham-Stout disease: the first case report.

Background: Gorham-Stout disease (GSD) is a form of lymphangiomatosis of unknown etiology, characterized by abnormal distribution of lymphatic vessels. Platelets and lymphangiogenesis are closely related via C-type lectin-like receptor 2 (CLEC-2)/podoplanin. Key Clinical Question: Despite similarities between abnormal lymphatic vessels in CLEC-2-deficient mice and patients with GSD, whether CLEC-2 on platelets is involved in GSD pathogenesis is unknown. Clinical Approach: We examined CLEC-2 expression in platelets of a patient with lethal GSD. Most of the patient's platelets expressed aberrant CLEC-2 that was not detectable by certain monoclonal antibodies for human CLEC-2. Further, this population was not activated by a CLEC-2-activating snake venom, rhodocytin. Possible causes of abnormal CLEC-2 including anti-CLEC-2 autoantibodies, podoplanin binding to CLEC-2, and pathogenic CLEC1B gene alteration were excluded. Conclusions: We believe that this is the first report of a patient with structurally and functionally abnormal CLEC-2. CLEC-2 abnormality may be associated with dysregulated lymphangiogenesis in GSD.

C-type lectin-like receptor-2 (CLEC-2) is a key regulator of kappa-carrageenan-induced tail thrombosis model in mice.

Kappa-carrageenan (KCG), which is used to induce thrombosis in laboratory animals for antithrombotic drug screening, can trigger platelet aggregation. However, the cell-surface receptor and related signaling pathways remain unclear. In this study, we investigated the molecular basis of KCG-induced platelet activation using light-transmittance aggregometry, flow cytometry, western blotting, and surface plasmon resonance assays using platelets from platelet receptor-deficient mice and recombinant proteins. KCG-induced tail thrombosis was also evaluated in mice lacking the platelet receptor. We found that KCG induces platelet aggregation with α-granule secretion, activated integrin αIIbß3, and phosphatidylserine exposure. As this aggregation was significantly inhibited by the Src family kinase inhibitor and spleen tyrosine kinase (Syk) inhibitor, a tyrosine kinase-dependent pathway is required. Platelets exposed to KCG exhibited intracellular tyrosine phosphorylation of Syk, linker activated T cells, and phospholipase C gamma 2. KCG-induced platelet aggregation was abolished in platelets from C-type lectin-like receptor-2 (CLEC-2)-deficient mice, but not in platelets pre-treated with glycoprotein VI-blocking antibody, JAQ1. Surface plasmon resonance assays showed a direct association between murine/human recombinant CLEC-2 and KCG. KCG-induced thrombosis and thrombocytopenia were significantly inhibited in CLEC-2-deficient mice. Our findings show that KCG induces platelet activation via CLEC-2.

Thrombosis is a serious medical condition that occurs when blood clots form in the blood vessels and can lead to heart attacks or strokes. Animal models are important for evaluating the effectiveness of drugs in thrombosis treatment. Kappa-carrageenan (KCG) is a food thickener and a substance used to induce clot formation in laboratory animals. In this study, we investigated the molecular basis of KCG-induced platelet activation, which is an important step in thrombosis development. We found that KCG activates platelets via a receptor called C-type lectin-like receptor 2 (CLEC-2), leading to a prothrombotic state in mice. We also showed that KCG-induced tail thrombosis (CTT) is significantly inhibited in CLEC-2 deficient mice. Our findings suggest that CLEC-2-mediated platelet activation plays a key role in the pathogenesis of thrombosis and CLEC-2 May participate in innate immunity as a receptor for sulfate-polysaccharide.Abbreviation; CLEC-2: C-type lectin-like receptor 2; CRP: collagen-related peptide; CTT: KCGN-induced tail thrombosis; DIC: disseminated intravascular coagulation; EDTA: ethylenediaminetetraacetic acid; GPVI: glycoprotein VI; HRP: horseradish peroxidase; KCG: Κ-Carrageenan; LAT: linker activated T cells; LDS: lithium dodecyl sulfate; LTA: light-transmittance aggregometry; MFI: mean fluorescence intensity; PFA: paraformaldehyde; PLCγ2: phospholipase C gamma 2; PS: phosphatidylserine; Syk: spleen tyrosine kinase; Co-HP: Cobalt-hematoporphyrin.

Inhibition of cancer cell­platelet adhesion as a promising therapeutic target for preventing peritoneal dissemination of gastric cancer.

Platelets form complexes with gastric cancer (GC) cells via direct contact, enhancing their malignant behavior. In the present study, the molecules responsible for GC cell-platelet interactions were examined and their therapeutic application in inhibiting the peritoneal dissemination of GC was investigated. First, the inhibitory effects of various candidate surface molecules were investigated on platelets and GC cells, such as C-type lectin-like receptor 2 (CLEC-2), glycoprotein VI (GPVI) and integrin αIIbß3, in the platelet-induced enhancement of GC cell malignant potential. Second, the therapeutic effects of molecules responsible for the development and progression of GC were investigated in a mouse model of peritoneal dissemination. Platelet-induced enhancement of the migratory ability of GC cells was markedly inhibited by an anti-GPVI antibody and inhibitor of galectin-3, a GPVI ligand. However, neither the CLEC-2 inhibitor nor the integrin-blocking peptide significantly suppressed this enhanced migratory ability. In experiments using mouse GC cells and platelets, the migratory and invasive abilities enhanced by platelets were significantly suppressed by the anti-GPVI antibody and galectin-3 inhibitor. Furthermore, in vivo analyses demonstrated that the platelet-induced enhancement of peritoneal dissemination was significantly suppressed by the coadministration of anti-GPVI antibody and galectin-3 inhibitor, and was nearly eliminated by the combined treatment. The inhibition of adhesion resulting from GPVI-galectin-3 interaction may be a promising therapeutic strategy for preventing peritoneal dissemination in patients with GC.

Soluble C-type lectin-like receptor 2 in stroke (CLECSTRO) study: protocol of a multicentre, prospective cohort of a novel platelet activation marker in acute ischaemic stroke and transient ischaemic attack.

INTRODUCTION: Soluble C-type lectin-like receptor 2 (sCLEC-2) is a new biomarker for platelet activation, which can be easily measured by usual blood collection. We conducted the CLECSTRO, a prospective, observational cohort study, to evaluate the clinical implications of sCLEC-2 in patients with acute ischaemic stroke (AIS) and transient ischaemic attack (TIA). METHODS AND ANALYSIS: The participants are patients with AIS/TIA and control patients required for differentiation from AIS/TIA. The target population is 600, including the patients and controls, who would be recruited from eight stroke centres across Japan. The inclusion criteria are AIS within 24 hours of onset and a modified Rankin Scale (mRS) score of 0-2, TIA within 7 days of onset, and contemporary patients required for differentiation from AIS/TIA. Plasma sCLEC-2 will be measured by high-sensitive chemiluminescent enzyme immunoassay using residual blood samples from routine laboratory examinations at the first visit in all patients and 7 days later or at discharge in patients with AIS/TIA. The outcomes include plasma levels of sCLEC-2 in patients with AIS/TIA and controls, sCLEC-2/D-dimer ratio in non-cardioembolic and cardioembolic AIS/TIA, correlation of sCLEC-2 with recurrence or worsening of stroke, severity of stroke, infarct size, ABCD2 score in TIA and outcome (mRS) at 7 days and 3 months. ETHICS AND DISSEMINATION: This study was approved by the Ethical Committee of the University of Yamanashi as the central ethical committee in agreement with the ethical committees of all collaborative stroke centres. Informed consent will be obtained by an opt-out form from the patients at each stroke centre according to the Ethical Guidelines for Medical and Biological Research Involving Human Subjects by the Japanese Ministry of Health, Labour and Welfare. TRIAL REGISTRATION NUMBERS: NCT05579405, UMIN000048954.

High plasma soluble CLEC-2 level predicts oxygen therapy requirement in patients with COVID-19.

Predicting the clinical course and allocating limited medical resources appropriately is crucial during the COVID-19 pandemic. Platelets are involved in microthrombosis, a critical pathogenesis of COVID-19; however, the role of soluble CLEC-2 (sCLEC-2), a novel platelet activation marker, in predicting the prognosis of COVID-19 remains unexplored. We enrolled 108 patients with COVID-19, hospitalized between January 2021 and May 2022, to evaluate the clinical use of sCLEC-2 as a predictive marker. sCLEC-2 levels were measured in plasma sampled on admission, as well as interleukin-6, cell-free DNA, von Willebrand factor, and thrombomodulin. We retrospectively classified the patients into two groups - those who required oxygenation during hospitalization (oxygenated group) and those who did not (unoxygenated group) - and compared their clinical and laboratory characteristics. The correlation between sCLEC-2 and the other parameters was validated. The sCLEC-2 level was significantly higher in the oxygenated group (188.8 pg/mL vs. 296.1 pg/mL). Multivariate analysis identified high sCLEC-2 levels (odds ratio per 10 pg/mL:1.25) as an independent predictor of oxygen therapy requirement. sCLEC-2 was positively correlated with cell-free DNA, supporting the association between platelet activation and neutrophil extracellular traps. In conclusion, sCLEC-2 is a clinically valuable marker in predicting oxygen therapy requirements for patients with COVID-19.

What is the context? During the COVID-19 epidemic with tremendous damage to healthcare systems worldwide, predicting the clinical course of patients and allocating limited medical resources appropriately is crucial.Platelets are involved in microthrombosis - a critical pathogenesis of COVID-19. The role of soluble CLEC-2 (sCLEC-2), a novel in vivo platelet activation marker, in predicting the prognosis of COVID-19 remains unexplored.What is new? sCLEC-2 is an independent predictive marker of oxygen therapy requirement in COVID-19.What is the impact? In most cases, patients requiring oxygen therapy must be hospitalized. The ability to predict such cases during the COVID-19 epidemic, when medical recourses are depleted, may contribute to the appropriate allocation of medical resources.

Impact of Hemostasis on the Lymphatic System in Development and Disease.

Lymphatic vessels form a systemic network that maintains interstitial fluid homeostasis and regulates immune responses and is strictly separated from the circulatory system. During embryonic development, lymphatic endothelial cells originate from blood vascular endothelial cells in the cardinal veins and form lymph sacs. Platelets are critical for separating lymph sacs from the cardinal veins through interactions between CLEC-2 (C-type lectin-like receptor-2) and PDPN (podoplanin) in lymphatic endothelial cells. Therefore, deficiencies of these genes cause blood-filled lymphatic vessels, leading to abnormal lymphatic vessel maturation. The junction between the thoracic duct and the subclavian vein has valves and forms physiological thrombi dependent on CLEC-2/PDPN signaling to prevent blood backflow into the thoracic duct. In addition, platelets regulate lymphangiogenesis and maintain blood/lymphatic separation in pathological conditions, such as wound healing and inflammatory diseases. More recently, it was reported that the entire hemostatic system is involved in lymphangiogenesis. Thus, the hemostatic system plays a crucial role in the establishment, maintenance, and rearrangement of lymphatic networks and contributes to body fluid homeostasis, which suggests that the hemostatic system is a potential target for treating lymphatic disorders. This review comprehensively summarizes the role of the hemostatic system in lymphangiogenesis and lymphatic vessel function and discusses challenges and future perspectives.

Super Formula for Diagnosing Disseminated Intravascular Coagulation Using Soluble C-Type Lectin-like Receptor 2.

The scoring systems for disseminated intravascular coagulation (DIC) criteria require several adequate cutoff values, vary, and are complicated. Accordingly, a simpler and quicker diagnostic method for DIC is needed. Under such circumstances, soluble C-type lectin-like receptor 2 (sCLEC-2) received attention as a biomarker for platelet activation. MATERIALS AND METHODS: The diagnostic usefulness of sCLEC-2 and several formulas, including sCLEC-2xD-dimer, sCLEC-2/platelet count (sCLEC-2/PLT), and sCLEC-2/PLT × D-dimer (sCLEC-2xD-dimer/PLT), were evaluated among 38 patients with DIC, 39 patients with pre-DIC and 222 patients without DIC or pre-DIC (non-DIC). RESULTS: Although the plasma level of sCLEC-2 alone was not a strong biomarker for the diagnosis of DIC or pre-DIC, the sCLEC-2xD-dimer/PLT values in patients with DIC were significantly higher than those in patients without DIC, and in a receiver operating characteristic (ROC) analysis for the diagnosis of DIC, sCLEC-2xD-dimer/PLT showed the highest AUC, sensitivity, and odds ratio. This formula is useful for the diagnosis of both pre-DIC and DIC. sCLEC-2xD-dimer/PLT values were significantly higher in non-survivors than in survivors. CONCLUSION: The sCLEC-2xD-dimer/PLT formula is simple, easy, and highly useful for the diagnosis of DIC and pre-DIC without the use of a scoring system.

Cancer-associated fibroblasts promote venous thrombosis through podoplanin/CLEC-2 interaction in podoplanin-negative lung cancer mouse model.

BACKGROUND: Cancer-associated thrombosis (CAT) is the leading cause of morbidity and mortality. Cancer-associated fibroblasts (CAFs) are a prominent component of the tumor microenvironment that contributes to cancer progression through direct cell-cell interactions and the release of extracellular vesicles (EVs). However, the role of CAFs in CAT remains unclear. OBJECTIVE: This study aims to investigate whether CAFs aggravate CAT and the underlying molecular mechanism using a preclinical mouse lung cancer model. METHODS: We designed a Lewis lung carcinoma (LLC) tumor-bearing mouse model. CAFs were characterized using fluorescence immunohistostaining. The presence of podoplanin, a platelet-activating membrane protein through C-type lectin-like receptor 2 (CLEC-2), in EVs isolated from primary CAFs or LLC tumor tissues was assessed by immunoblotting. The platelet activation and aggregation abilities of the EVs were quantified using flow cytometry. Podoplanin plasma levels were measured by enzyme-linked immunosorbent assay. Venous thrombosis was induced in the femoral vein using 2.5% ferric chloride. The anti-CLEC-2 monoclonal antibody 2A2B10 was used to deplete CLEC-2 on the surface of the platelets. RESULTS: CAFs expressing CD90, PDGFRß, HSP47, CD34, and vimentin, co-expressed podoplanin and induced platelet activation and aggregation in a CLEC-2-dependent manner. Tumor-bearing mice showed elevated podoplanin plasma levels. CAF-EV injection and tumor-bearing mice showed shorter occlusion time in the venous thrombosis model. Although tumor growth was not altered, antibody-induced CLEC-2 depletion suppressed venous thrombosis in the tumor-bearing state but not in the healthy condition. CONCLUSION: CAFs and CAF-derived EVs induce CLEC-2-dependent platelet aggregation and aggravate venous thrombosis.

Thrombotic Mechanism Involving Platelet Activation, Hypercoagulability and Hypofibrinolysis in Coronavirus Disease 2019.

Coronavirus disease 2019 (COVID-19) has spread, with thrombotic complications being increasingly frequently reported. Although thrombosis is frequently complicated in septic patients, there are some differences in the thrombosis noted with COVID-19 and that noted with bacterial infections. The incidence (6-26%) of thrombosis varied among reports in patients with COVID-19; the incidences of venous thromboembolism and acute arterial thrombosis were 4.8-21.0% and 0.7-3.7%, respectively. Although disseminated intravascular coagulation (DIC) is frequently associated with bacterial infections, a few cases of DIC have been reported in association with COVID-19. Fibrin-related markers, such as D-dimer levels, are extremely high in bacterial infections, whereas soluble C-type lectin-like receptor 2 (sCLEC-2) levels are high in COVID-19, suggesting that hypercoagulable and hyperfibrinolytic states are predominant in bacterial infections, whereas hypercoagulable and hypofibrinolytic states with platelet activation are predominant in COVID-19. Marked platelet activation, hypercoagulability and hypofibrinolytic states may cause thrombosis in patients with COVID-19.

Advancing Tissue Factor-targeted Therapy for Osteosarcoma via Understanding its Role in the Tumor Microenvironment.

Coagulation activation is associated with cancer progression and morbidity. Recently, mechanisms through which coagulation proteases drive the tumor microenvironment (TME) have been elucidated. This review aims to develop a new strategy dependent on the coagulation system for treating osteosarcoma (OS). We focused on tissue factor (TF), the main initiator of the extrinsic coagulant pathway, as a target for OS treatment. It was found that cell surface-TF, TF-positive extracellular vesicles, and TF-positive circulating tumor cells could drive progression, metastasis, and TME in carcinomas, including OS. Thus, targeting tumor-associated coagulation by focusing on TF, the principle catalyst of the extrinsic pathway, TF is a promising target for OS.

Illustrated State-of-the-Art Capsules of the ISTH 2022 Congress.

The ISTH London 2022 Congress is the first held (mostly) face-to-face again since the COVID-19 pandemic took the world by surprise in 2020. For 2 years we met virtually, but this year's in-person format will allow the ever-so-important and quintessential creativity and networking to flow again. What a pleasure and joy to be able to see everyone! Importantly, all conference proceedings are also streamed (and available recorded) online for those unable to travel on this occasion. This ensures no one misses out. The 2022 scientific program highlights new developments in hemophilia and its treatment, acquired and other inherited bleeding disorders, thromboinflammation, platelets and coagulation, clot structure and composition, fibrinolysis, vascular biology, venous thromboembolism, women's health, arterial thrombosis, pediatrics, COVID-related thrombosis, vaccine-induced thrombocytopenia with thrombosis, and omics and diagnostics. These areas are elegantly reviewed in this Illustrated Review article. The Illustrated Review is a highlight of the ISTH Congress. The format lends itself very well to explaining the science, and the collection of beautiful graphical summaries of recent developments in the field are stunning and self-explanatory. This clever and effective way to communicate research is revolutionary and different from traditional formats. We hope you enjoy this article and will be inspired by its content to generate new research ideas.

Periosteum-derived podoplanin-expressing stromal cells regulate nascent vascularization during epiphyseal marrow development.

Bone marrow development and endochondral bone formation occur simultaneously. During endochondral ossification, periosteal vasculatures and stromal progenitors invade the primary avascular cartilaginous anlage, which induces primitive marrow development. We previously determined that bone marrow podoplanin (PDPN)-expressing stromal cells exist in the perivascular microenvironment and promote megakaryopoiesis and erythropoiesis. In this study, we aimed to examine the involvement of PDPN-expressing stromal cells in postnatal bone marrow generation. Using histological analysis, we observed that periosteum-derived PDPN-expressing stromal cells infiltrated the cartilaginous anlage of the postnatal epiphysis and populated on the primitive vasculature of secondary ossification center. Furthermore, immunophenotyping and cellular characteristic analyses indicated that the PDPN-expressing stromal cells constituted a subpopulation of the skeletal stem cell lineage. In vitro xenovascular model cocultured with human umbilical vein endothelial cells and PDPN-expressing skeletal stem cell progenies showed that PDPN-expressing stromal cells maintained vascular integrity via the release of angiogenic factors and vascular basement membrane-related extracellular matrices. We show that in this process, Notch signal activation committed the PDPN-expressing stromal cells into a dominant state with basement membrane-related extracellular matrices, especially type IV collagens. Our findings suggest that the PDPN-expressing stromal cells regulate the integrity of the primitive vasculatures in the epiphyseal nascent marrow. To the best of our knowledge, this is the first study to comprehensively examine how PDPN-expressing stromal cells contribute to marrow development and homeostasis.

Elevated Plasma Soluble C-Type Lectin-like Receptor 2 Is Associated with the Worsening of Coronavirus Disease 2019.

Although thrombosis in coronavirus disease 2019 (COVID-19) infection has attracted attention, the mechanism underlying its development remains unclear. The relationship between platelet activation and the severity of COVID-19 infection was compared with that involving other infections. Plasma soluble C-type lectin-like receptor 2 (sCLEC-2) levels were measured in 46 patients with COVID-19 infection and in 127 patients with other infections. The plasma sCLEC-2 levels in patients with COVID-19 infection {median (25th, 75th percentile), 489 (355, 668) ng/L} were significantly higher (p < 0.001) in comparison to patients suffering from other pneumonia {276 (183, 459) ng/L}, and the plasma sCLEC-2 levels of COVID-19 patients with severe {641 (406, 781) ng/L} or critical illness {776 (627, 860) ng/L} were significantly higher (p < 0.01, respectively) in comparison to those with mild illness {375 (278, 484) ng/L}. The ratio of the sCLEC-2 levels to platelets in COVID-19 patients with critical illness of infection was significantly higher (p < 0.01, p < 0.001 and p < 0.05, respectively) in comparison to COVID-19 patients with mild, moderate or severe illness. Plasma sCLEC-2 levels were significantly higher in patients with COVID-19 infection than in those with other infections, suggesting that platelet activation is triggered and facilitated by COVID-19 infection.

Early recognition of sepsis-induced coagulopathy using the C2PAC index: a ratio of soluble type C lectin-like receptor 2 (sCLEC-2) level and platelet count.

C-type lectin-like receptor 2 (CLEC-2) is a platelet-activated receptor expressed on the surface of platelet membranes. Soluble CLEC-2 (sCLEC-2) has been receiving attention as a predictive marker for thrombotic predisposition. The present study examined the relationship between sCLEC-2 level and degree of coagulation disorder in septic patients. Seventy septic patients were divided into the sepsis-induced disseminated intravascular coagulation (DIC) (SID) group (n = 44) and non-SID group (n = 26). The sCLEC-2 levels were compared between the two groups. Because we suspected that the sCLEC-2 level was affected by the platelet count, we calculated the sCLEC-2/platelet count ratio (C2PAC index). We further divided septic patients into four groups using the Japanese Association for Acute Medicine (JAAM) DIC scoring system (DIC scores: 0-1, 2-3, 4-5, and 6-8). The C2PAC index was significantly higher in the SID group (2.6 ± 1.7) compared with the non-SID group (1.2 ± 0.5) (P < .001). The C2PAC indexes in the four JAAM DIC score groups were 0.9 ± 0.3, 1.1 ± 0.3, 1.7 ± 0.7, and 3.6 ± 1.0, respectively, and this index increased significantly as the DIC score increased (P < .001). According to the receiver-operating curve analysis, the area under the curve (AUC) and optimal cutoff value for the diagnosis of SID were 0.8051 and 1.4 (sensitivity, 75.0%; specificity, 76.9%), respectively. When the C2PAC index and D-dimer level, one of the main fibrinolytic markers, were selected as predictive markers for SID diagnosis in stepwise multiple logistic regression analysis, it was possible to diagnose SID with a high probability (AUC, 0.9528; sensitivity, 0.9545; specificity, 0.8846). The C2PAC index is a useful predictor of SID progression and diagnosis in septic patients.

Detection of SARS-CoV-2 RNA Using RT-qPCR in Saliva Samples and Nasopharyngeal, Lingual, and Buccal Mucosal Swabs.

Coronavirus disease 2019 is diagnosed based on the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in nasopharyngeal swabs or saliva samples using reverse-transcription quantitative polymerase chain reaction. Nasopharyngeal swabs should be collected by medical professionals who are covered with full personal protective equipment (PPE), while saliva samples can be collected by patients themselves without any PPE. However, collecting saliva is difficult for people who are unable to follow instructions, including infants or unconscious patients. Owing to the high viscosity of saliva, special attention is required to handle saliva samples in laboratories. To solve these problems, we compared lingual and buccal mucosal swabs (oral swabs) with nasopharyngeal swabs and saliva samples. Among 13 patients who had a positive result for SARS-CoV-2 RNA in their nasopharyngeal swabs, 8 and 10 patients had a positive result for SARS-CoV-2 RNA in their saliva (concordance rate, 61.5%) and oral swabs (76.9%), respectively. Among the eight patients with a positive result for SARS-CoV-2 RNA in saliva, seven (87.5%) had SARS-CoV-2 detected in their oral swabs. We could not obtain saliva samples from four patients, but we found perfect concordance of SARS-CoV-2 positivity between the nasopharyngeal and oral swabs. Therefore, oral swabs can be used for SARS-CoV-2 RNA detection.

Soluble C-Type Lectin-Like Receptor 2 Elevation in Patients with Acute Cerebral Infarction.

BACKGROUND: Acute cerebral infarction (ACI) includes cardiogenic ACI treated with anticoagulants and atherosclerotic ACI treated with antiplatelet agents. The differential diagnosis between cardiogenic and atherosclerotic ACI is still difficult. MATERIALS AND METHODS: The plasma sCLEC-2 and D-dimer levels were measured using the STACIA system. RESULTS: The plasma sCLEC-2 level was significantly high in patients with ACI, especially those in patients with atherosclerotic or lacunar ACI, and plasma D-dimer levels were significantly high in patients with cardioembolic ACI. The plasma levels of sCLEC-2 and the sCLEC-2/D-dimer ratios in patients with atherosclerotic or lacunar ACI were significantly higher than those in patients with cardioembolic ACI. The plasma D-dimer levels in patients with atherosclerotic or lacunar ACI were significantly lower than those in patients with cardioembolic ACI. The plasma levels of sCLEC-2 and the sCLEC-2/D-dimer ratios were significantly higher in patients with atherosclerotic or lacunar ACI or acute myocardial infarction in comparison to patients with cardioembolic ACI or those with deep vein thrombosis. CONCLUSION: Using both the plasma sCLEC-2 and D-dimer levels may be useful for the diagnosis of ACI, and differentiating between atherosclerotic and cardioembolic ACI.

Soluble C-Type Lectin-Like Receptor 2 Is a Biomarker for Disseminated Intravascular Coagulation.

Disseminated intravascular coagulation (DIC) is induced by excess activation coagulation, and activated platelets are also involved in pathogenesis. Therefore, plasma levels of soluble C-type lectin-like receptor 2 (sCLEC-2), a new marker for platelet activation, can be expected as a marker of DIC in critically ill patients. Plasma levels of sCLEC-2 and D-dimer were measured using the STACIA system. Plasma sCLEC-2 and D-dimer levels were significantly higher in patients with underlying diseases of DIC than in those with unidentified clinical syndrome (UCS). Plasma sCLEC-2 levels were significantly higher in the patients with DIC and Pre-DIC than in those without DIC or Pre-DIC. Similarly, plasma D-dimer levels were also significantly higher in patients with DIC and Pre-DIC than in those without DIC or Pre-DIC. The plasma sCLEC-2 levels in all patients and those with a DIC score ≤ 4 were significantly higher in non-survivors than survivors. The plasma D-dimer levels in all patients, those with a DIC score ≥ 5 and those with a DIC score ≤ 4, were significantly higher in non-survivors than in survivors. The plasma sCLEC-2 is expected as a marker for DIC/Pre-DIC as well as the prognostic marker in critically ill patients.