Biology and functions of fish thrombocytes: A review.

This comprehensive review examines the role of fish thrombocytes, cells considered functionally analogous to platelets in terms of coagulation, but which differ in their origin and morphology. Despite the evolutionary distance between teleosts and mammals, genomic studies reveal conserved patterns in blood coagulation, although there are exceptions such as the absence of factors belonging to the contact system. Beyond coagulation, fish thrombocytes have important immunological functions. These cells express both proinflammatory genes and genes involved in antigen presentation, suggesting a role in both innate and adaptive immune responses. Moreover, having demonstrated their phagocytic abilities, crucial in the fight against pathogenic microorganisms, underscores their multifaceted involvement in immunity. Finally, the need for further research on the functions of these cells is highlighted, in order to better understand their involvement in maintaining the health of aquaculture fish. The use of standardized and automated methods for the analysis of these activities is advocated, emphaiszing their potential to facilitate the early detection of stress or infection, thus minimizing the economic losses that these adverse situations can generate in the field of aquaculture.

Platelet count and platelet-to-lymphocyte ratio at the onset of a severe COPD exacerbation are unrelated to the time till the next moderate or severe relapse.

PURPOSE: Acute exacerbations (AE) are severe complications of chronic obstructive pulmonary disease (COPD); however, the need for biomarkers which predict them is still unmet. High platelet count (PLC) and platelet-to-lymphocyte ratio (PLR) are associated with higher mortality in patients with COPD. We investigated if PLC and PLR at the onset of a severe AE could predict the time of the next relapse. METHODS: In a prospective observational cohort study, data of 152 patients hospitalized with AECOPD were collected, and patients were divided into PLC-low (<239 â€‹× â€‹109/L, n â€‹= â€‹51), PLC-medium (239-297 â€‹× â€‹109/L, n â€‹= â€‹51) and PLC-high (>297 â€‹× â€‹109/L, n â€‹= â€‹50) or PLR-low (<147, N â€‹= â€‹51), PLR-medium (147-295, n â€‹= â€‹51) and PLR high (>295, n â€‹= â€‹50) groups based on PLC and PLR tertiles using admission laboratory results. Clinical characteristics and the time to the next severe or moderate AE within 52 weeks were compared among subgroups using log-rank test. RESULTS: PLC and PLR tertiles did not differ in clinical characteristics or the time till the next AE (p â€‹> â€‹0.05). PLC and PLR showed a direct weak correlation to neutrophil count (Pearson r â€‹= â€‹0.26, p â€‹< â€‹0.01 and r â€‹= â€‹0.20, p â€‹= â€‹0.01) and PLC also demonstrated a weak relationship to white blood cell counts (Pearson r â€‹= â€‹0.29, p â€‹< â€‹0.001). However, PLR presented an inverse relationship to monocyte and eosinophil counts (r â€‹= â€‹-0.32, p â€‹< â€‹0.001 and r â€‹= â€‹-0.17, p â€‹= â€‹0.03). CONCLUSION: PLC and PLR do not predict the time till the next relapse; however, they may reflect on neutrophilic inflammatory response during an exacerbation of COPD.

The effect of normobaric hypoxia on acute exercise-induced changes in blood sphingoid base-1-phosphates metabolism in cyclists.

Extracellular sphingosine-1-phosphate (S1P) emerged as an important regulator of muscle function. We previously found that plasma S1P concentration is elevated in response to acute exercise and training. Interestingly, hypoxia, which is commonly utilized in training programs, induces a similar effect. Therefore, the aim of the current study was to determine the effect of normobaric hypoxia on exercise-induced changes in blood sphingolipid metabolism. Fifteen male competitive cyclists performed a graded cycling exercise until exhaustion (GE) and a simulated 30 km individual time trial (TT) in either normoxic or hypoxic (FiO2 = 16.5%) conditions. Blood samples were taken before the exercise, following its cessation, and after 30 min of recovery. We found that TT increased dihydrosphingosine-1-phosphate (dhS1P) concentration in plasma (both HDL- and albumin-bound) and blood cells, as well as the rate of dhS1P release from erythrocytes, regardless of oxygen availability. Plasma concentration of S1P was, however, reduced during the recovery phase, and this trend was augmented by hypoxia. On the other hand, GE in normoxia induced a selective increase in HDL-bound S1P. This effect disappeared when the exercise was performed in hypoxia, and it was associated with reduced S1P level in platelets and erythrocytes. We conclude that submaximal exercise elevates total plasma dhS1P concentration via increased availability of dihydrosphingosine resulting in enhanced dhS1P synthesis and release by blood cells. Maximal exercise, on the other hand, induces a selective increase in HDL-bound S1P, which is a consequence of mechanisms not related to blood cells. We also conclude that hypoxia reduces post-exercise plasma S1P concentration.

Injections of Platelet-Rich Plasma: An Emerging Novel Biological Cure for Low Back Pain?

Autologous platelet-rich plasma (PRP) injections have emerged as a new biological intervention for many musculoskeletal conditions, such as low back pain (LBP), and have garnered significant attention in recent research endeavors. The recognition of PRP's use is progressively growing; nonetheless, comprehensive clinical validation is required to establish its uses and efficiency. This article offers a thorough evaluation regarding the assurance as well as the efficacy of PRP therapy in the management of low back pain. It specifically focuses on the analysis of clinical trials undertaken in this field.

Convolutional neuronal network for identifying single-cell-platelet-platelet-aggregates in human whole blood using imaging flow cytometry.

Imaging flow cytometry is an attractive method to investigate individual cells by optical properties. However, imaging flow cytometry applications with clinical relevance are scarce so far. Platelet aggregation naturally occurs during blood coagulation to form a clot. However, aberrant platelet aggregation is associated with cardiovascular disease under steady-state conditions in the blood. Several types of so-called antiplatelet drugs are frequently described to reduce the risk of stroke or cardiovascular diseases. However, an efficient monitoring method is missing to identify the presence and frequency of platelet-platelet aggregates in whole blood on a single cell level. In this work, we employed imaging flow cytometry to identify fluorescently labeled platelets in whole blood with a conditional gating strategy. Images were post-processed and aligned. A convolutional neural network was designed to identify platelet-platelet aggregates of two, three, and more than three platelets, and results were validated against various data set properties. In addition, the neural network excluded erythrocyte-platelet aggregates from the results. Based on the results, a parameter for detecting platelet-platelet aggregates, the weighted platelet aggregation, was developed. If employed on a broad scale with proband and patient samples, our method could aid in building a future diagnostic marker for cardiovascular disease and monitoring parameters to optimize drug prescriptions in such patient groups.

Feasibility and comparability of different platelet function tests in acute stroke with or without prior antiplatelet therapy.

Background: The clinical course of ischemic and hemorrhagic strokes can be influenced by the coagulation status of individual patients. The prior use of antiplatelet therapy (APT) such as acetylsalicylic acid (ASA) or P2Y12-antagonists has been inconsistently described as possibly increasing the risk of hemorrhagic transformation or expansion. Since clinical studies describing prior use of antiplatelet medication are overwhelmingly lacking specific functional tests, we aimed to implement testing in routine stroke care. Methods: We used fluorescence-activated cell sorting (FACS) with antibodies against CD61 for thrombocyte identification and CD62p or platelet activation complex-1 (PAC-1) to determine platelet activation. Aggregometry and automated platelet functioning analyzer (PFA-200) were employed to test thrombocyte reactivity. FACS and aggregometry samples were stimulated in vitro with arachidonic acid (AA) and adenosine diphosphate (ADP) to measure increase in CD62p-/PAC-1-expression or aggregation, respectively. Results: Between February and July 2023, 20 blood samples (n = 11 ischemic strokes; n = 7 hemorrhagic strokes; n = 2 controls) were acquired and analyzed within 24 h of symptom onset. N = 11 patients had taken ASA, n = 8 patients no APT and n = 1 ASA+clopidogrel. ASA intake compared to no APT was associated with lower CD62p expression after stimulation with AA on FACS analysis (median 15.8% [interquartile range {IQR} 12.6-37.2%] vs. 40.1% [IQR 20.3-56.3%]; p = 0.020), lower platelet aggregation (9.0% [IQR 7.0-12.0%] vs. 88.5% [IQR 11.8-92.0%]; p = 0.015) and longer time to plug formation with PFA-200 (248.0 s [IQR 157.0-297] vs. 121.5 s [IQR 99.8-174.3]; p = 0.027). Significant correlations were noted between AA-induced CD62p expression and aggregometry analysis (n = 18; ρ = 0.714; p < 0.001) as well as a negative correlation between CD62p increase and PFA clot formation time (n = 18; ρ = -0.613; p = 0.007). Sensitivity for ASA intake was highest for PFA (81.8% for values ≥155.5 s). The combination of ASA + clopidogrel also affected ADP-induced CD62p and PAC-1 expression. Conclusion: In the clinical setting it is feasible to use differentiated platelet analytics to determine alterations caused by antiplatelet therapy. Among the tests under investigation, PFA-200 showed the highest sensitivity for the intake of ASA in stroke patients. FACS analysis on the other hand might be able to provide a more nuanced approach to altered platelet reactivity.

Reproducibility and stability of the immature platelet fraction using Sysmex XN-10.

BACKGROUND: The Immature Platelet Fraction (IPF) is an indicator of thrombopoiesis which is a useful parameter in thrombocytopenia. It demonstrates compensatory mechanisms in production of platelets, but currently not implemented in routine clinical practice. The aim of this study was to establish the reproducibility and stability of IPF, for both percentage (%-IPF) and absolute (A-IPF) measurements.Material/methods: A total of 71 samples, of which 45 for reproducibility and 26 for stability analysis, were assayed for full blood count using the Sysmex XN-10 analyser at room temperature (RT:19-25 °C). For reproducibility analysis, IPF measurements were analysed 11 times by different appraisers using the same sample, while for stability analysis, IPF was measured over fourteen hourly-intervals up to 24 h (n = 21) and then separately extended beyond the point of stability to 72 h (n = 5). RESULTS: Reproducibility analysis of %-IPF and A-IPF (n = 45) showed very reliable results, with the range of mean CV% values between 1.25-8.90% and 1.70-9.96%, respectively. On the other hand, overall, stability analysis of %-IPF and A-IPF (n = 21) at RT over 24 h showed reliable results, with pooled mean CV% values of 1.32% and 1.43%, respectively, with no significant difference between %-IPF and A-IPF (p = 0.767 and p = 0.821). All %-IPF and A-IPF values had exceeded the set acceptance criterion of stability (CV% ≥ 10.0%) before 72 h. CONCLUSIONS: Overall, %-IPF and A-IPF reproducibility and storage at RT for 24 h predominantly demonstrates the suitability of their usage for testing on the Sysmex XN-series analysers.

Composition of thrombi in zebrafish: similarities and distinctions with mammals.

BACKGROUND: Blood clots are primarily composed of red blood cells (RBCs), platelets/thrombocytes, and fibrin. Despite the similarities observed between mammals and zebrafish, the composition of fish thrombi is not as well known. OBJECTIVES: To analyze the formation of zebrafish blood clots ex vivo and arterial and venous thrombi in vivo. METHODS: Transgenic zebrafish lines and laser-mediated endothelial injury were used to determine the relative ratio of RBCs and thrombocytes in clots. Scanning electron and confocal microscopy provided high-resolution images of the structure of adult and larval clots. Adult and larval thrombocyte spreading on fibrinogen was evaluated ex vivo. RESULTS: RBCs were present in arterial and venous thrombi, making up the majority of cells in both circulations. However, bloodless mutant fish demonstrated that fibrin clots can form in vivo in the absence of blood cells. Scanning electron and confocal microscopy showed that larval and adult zebrafish thrombi and mammalian thrombi look surprisingly similar externally and internally, even though the former have nucleated RBCs and thrombocytes. Although adult thrombocytes spread on fibrinogen, we found that larval cells do not fully activate without the addition of plasma from adult fish, suggesting a developmental deficiency of a plasma activating factor. Finally, mutants lacking αIIbß3 demonstrated that this integrin mediates thrombocyte spreading on fibrinogen. CONCLUSION: Our data showed strong conservation of arterial and venous and clot/thrombus formation across species, including developmental regulation of thrombocyte function. This correlation supports the possibility that mammals also do not absolutely require circulating cells to form fibrin clots in vivo.

Discovery of seven hox genes in zebrafish thrombopoiesis.

Thrombopoiesis is the production of platelets from megakaryocytes in the bone marrow of mammals. In fish, thrombopoiesis involves the formation of thrombocytes without megakaryocyte-like precursors but derived from erythrocyte thrombocyte bi-functional precursor cells. One unique feature of thrombocyte differentiation involves the maturation of young thrombocytes in circulation. In this study, we investigated the role of hox genes in zebrafish thrombopoiesis to model platelet production. We selected hoxa10b, hoxb2a, hoxc5a, hoxd3a, and hoxc11b from thrombocyte RNA expression data, and checked whether they are expressed in young or mature thrombocytes. We found hoxa10b, hoxb2a, hoxc5a, and hoxd3a were expressed in both young and mature thrombocytes and hoxc11b was expressed in only young thrombocytes. We then performed knockdowns of these 5 hox genes and found hoxc11b knockdown resulted in thrombocytosis and the rest showed thrombocytopenia. To identify hox genes that could have been missed by the above datasets, we performed knockdowns 47 hox genes in the zebrafish genome and found hoxa9a, and hoxb1a knockdowns resulted in thrombocytopenia and they were expressed in both young and mature thrombocytes. In conclusion, our comprehensive knockdown study identified Hoxa10b, Hoxb2a, Hoxc5a, Hoxd3a, Hoxa9a, and Hoxb1a, as positive regulators and Hoxc11b, as a negative regulator for thrombocyte development.

Thrombocytes and Platelet-Rich Plasma as Modulators of Reproduction and Fertility.

Thrombocytes play an essential role in hemostasis and thrombosis. Moreover, the controlled activation of thrombocytes is required in reproduction and fertility. The platelet-activating factor and the controlled activation of platelets have important roles in folliculogenesis, ovulation, placental development, implantation and embryo development. Activated platelets accumulate in the follicular vessels surrounding the follicle and, due to its released soluble molecules (factors, mediators, chemokines, cytokines, neurotransmitters), locally increase oocyte maturation and hormone secretion. Furthermore, activated platelets are involved in the pathogenesis of ovarian hyperstimulation syndrome (OHSS) and preeclampsia. Low-dose aspirin can prevent OHSS during ovulation induction, while intrauterine or intraovarian administration of platelet-rich plasma (PRP) increases the endometrium thickness and receptivity as well as oocyte maturation. Activated thrombocytes rapidly release the contents of intracellular granules and have multiple adhesion molecules and receptors on their surface. Considering the numerous homeostatic endocrine functions of thrombocytes, it is reasonable to suppose a platelet-associated regulatory system (PARS) in reproduction. Although we are far from a complete understanding of the regulatory processes, the results of PARS research and the therapeutic application of aspirin and PRP during in vitro fertilization are promising.

CD41+ extracellular vesicles produced by avian thrombocytes contain microRNAs.

Avians have thrombocytes in their blood circulation rather than mammalian platelets. However, many details of thrombocyte characteristics have not been determined. Here, chicken thrombocytes were isolated, and extracellular vesicle (EV) production was investigated. The thrombocyte-specific markers cd41 and cd61 were expressed in the yolk sac at 24 h. According to the embryonic developmental stage, the cd41-expressing tissues changed from the yolk sac to the bone marrow and spleen. Accordingly, the bone marrow and spleen were the main tissues producing thrombocytes in adult chickens. Avian thrombocytes were separated from adult spleen cells through a combination of discontinuous density gradient centrifugation, phagocytic cell removal, and fluorescence-activated cell sorting. Isolated thrombocytes produced CD41+ EVs (CD41+ EVs), and the CD41+ EVs also expressed CD9. Microarray analysis revealed that CD41+ EVs contain many microRNAs. Macrophage lines (RAW264.7) phagocytosed CD41+ EVs, and their phagocytosis and migration activity were suppressed. Microarray analysis also revealed that EVs altered gene expression in macrophages. These data indicated that the CD41+ EV was a carrier of microRNAs produced from thrombocytes and affected the cell characteristics of the received cells. Therefore, the CD41+ EVs of avians worked as a communication tool.

[Platelet-rich plasma (PRP) : Compositional analysis with different dietary habits and timing of blood sampling]. / "Platelet-rich plasma" (PRP) : Analyse der Zusammensetzung bei unterschiedlichem Ernährungsverhalten und Blutentnahmezeitpunkt.

The variability of PRP is a major contributor to the lack of evidence regarding the therapeutic effect of PRP in musculoskeletal diseases. In a large study, we are currently investigating factors that may influence PRP variability. Interim results showed that concentrations of IL­6, but not IGF­1 or cellular constituents, were significantly decreased in PRP samples from vegans compared with omnivores and tended to be decreased compared to samples from vegetarians. This suggests that diet may have a significant influence on therapeutically active PRP constituents. However, the constituents studied here did not appear to be significantly affected by the timing of the sampling. Identification of significant variables affecting PRP composition will be critical to provide sufficient medical evidence for the therapeutic effects of PRP in orthopedic conditions.

A retrospective evaluation of phenobarbital-induced hematologic changes in 69 cats.

BACKGROUND: Phenobarbital (PB) is used as a first-line treatment for recurrent epileptic seizures in cats. While hematologic abnormalities are well-known side effects of antiepileptic therapy with PB in humans and dogs, little is known about such alterations in cats. OBJECTIVES: The aim of this retrospective study was to investigate the prevalence and clinical relevance of cytopenia during PB treatment in cats. METHODS: In this single-center, retrospective clinical study, 69 cats-with suspected idiopathic epilepsy admitted to the Small Animal Clinic of the University of Veterinary Medicine in Vienna (VMU)-were included. A complete blood count for each patient was performed, and changes in hematocrit, leukocytes, neutrophils, and thrombocytes were documented and graded. RESULTS: Fifty-three out of 69 cats (76.8%) showed cytopenias with a reduction of at least one cell fraction during PB treatment. The most frequent change was neutropenia (60%), followed by leukopenia (49.3%), thrombocytopenia (24.1%), and anemia (20.3%). Most of the changes were mild or moderate; only one patient (1.5%) showed severe leukopenia and neutropenia, and one was a life-threatening neutropenia (1.5%) with a serum PB concentration within or even below the therapeutic range. These patients did not present with clinical symptoms other than those related to epileptic episodes. Cats who received combination therapy showed lower hematocrits than those who received monotherapy. A tendency for leukocytes and neutrophils to decrease during PB treatment was also seen. CONCLUSIONS: Blood cytopenias may frequently occur in cats on chronic PB therapy, even when serum drug levels are within the therapeutic range. However, clinical signs are typically mild to moderate and rarely severe.

Thrombocyte decrease and hemoglobin level as simple non-inflammatory predictors of anastomotic leakage in rectal-cancer surger.

PURPOSE: The study aimed to determine a simple diagnostic test that could predict the risk of anastomotic leakage in early postoperative period. METHODS: A single-center, retrospective study was conducted. The electronic medical records of patients who underwent resection for rectal tumor between January 1, 2016, and December 31, 2021, in University Hospital Olomouc, were reviewed. The data included risk factors for leakage and laboratory parameters commonly obtained. RESULTS: The decrease in platelets was significant as for the possibility of being a marker of anastomotic leakage; OR = 0.980 (p = 0.036). A decrease of 34 or higher predicts leakage with a sensitivity of 45 % (95 % CI: 23.1-68.5 %) and specificity of 81.1 % (95 % CI: 75.2-86.1 %). Postoperative leukocyte blood level (OR = 1.134; p = 0.019) and leukocyte level on postoperative day 1 (OR = 1.184; p = 0.023) were significant predictors for leakage. WBC values ≥ 8.8 predict leakage with a sensitivity of 70.0 % (95 % CI: 45.7-88.1 %) and specificity of 55.3 % (95 % CI: 48.4-62.0 %).  Hemoglobin blood level ≤ 79.5 predicts leakage with a sensitivity of 70.0 % (95 % CI: 45.7-88.1 %) and specificity of 62.2 % (95 % CI: 55.5-68.7 %). CONCLUSION: Despite the fact that the specificity and sensitivity of the followed parameters are low, they could serve as markers useful for early diagnosis or suspicion for leakage (Tab. 5, Fig. 3, Ref. 14).

Gas plasma-induced platelet activation corresponds to reactive species profiles and lipid oxidation.

Surgical-induced hemostasis is a critical step in the closure of incisions, which is frequently achieved via electrocauterization and subsequent tissue necrotization. The latter is associated with postoperative complications. Recent in vivo work suggested reactive species-producing gas plasma technology as a pro-homeostatic agent acting via platelet activation. However, it remained elusive how platelet activation is linked to lipid and protein oxidation and the reactive species compositions. A direct relation between the reactive species composition and platelet activation was revealed by assessing the production of several reactive species and by using antioxidants. In addition, platelet lipidome and proteome analysis identified significantly regulated key lipids in the platelet activation pathway, such as diacylglycerols and phosphatidylinositol as well as oxylipins like thromboxanes. Lipid oxidation products mainly derived from phosphatidylethanolamine and phosphatidylserine species were observed at modest levels. In addition, oxidative post-translational modifications were identified on key proteins of the hemostasis machinery. This study provides new insights into oxidation-induced platelet activation in general and suggests a potential role of those processes in gas plasma-mediated hemostasis in particular.

An Overview of Risk Factors for Diabetic Foot Amputation: An Observational, Single-centre, Retrospective Cohort Study.

INTRODUCTION: Not only are early detection and treatment of diabetic foot ulcers important, but also acknowledging potential risk factors for amputation gives clinicians a considerable advantage in preventing amputations. Amputations impact both healthcare services and the physical and mental health of patients. This study aimed to investigate the risk factors for amputation in patients with diabetic foot ulcers. METHODS: The sample for this study was patients with diabetic foot ulcers who were treated by the diabetic foot council at our hospital between 2005 and 2020. A total of 32 risk factors for amputation were identified and investigated among 518 patients. RESULTS: Our univariate analysis showed that 24 of 32 defined risk factors were statistically significant. In the multivariate analysis using the Cox regression model, seven risk factors remained statistically significant. The risk factors most significantly associated with amputation were Wagner grading, abnormal peripheral arteries, hypertension, high thrombocyte levels, low haematocrit levels, hypercholesterolaemia and male sex, respectively. The most common cause of death in patients with diabetes who have undergone amputation is cardiovascular disease, followed by sepsis. CONCLUSION: To enable optimum treatment of patients with diabetic foot ulcers it is important for physicians to be aware of the amputation risk factors, and thus avoid amputations. Correcting risk factors, using suitable footwear and routinely inspecting feet are crucial factors for preventing amputations in patients with diabetic foot ulcers.

The efficacy of aspirin to inhibit platelet aggregation in patients hospitalised with a severe infection: a multicentre, open-label, randomised controlled trial.

Patients with severe infection have an increased risk of cardiovascular events. A possible underlying mechanism is inflammation-induced platelet aggregation. We investigated whether hyperaggregation occurs during infection, and whether aspirin inhibits this. In this multicentre, open-label, randomised controlled trial, patients hospitalised due to acute infection were randomised to receive 10 days of aspirin treatment (80 mg 1dd or 40 mg 2dd) or no intervention (1:1:1 allocation). Measurements were performed during infection (T1; days 1-3), after intervention (T2; day 14) and without infection (T3; day > 90). The primary endpoint was platelet aggregation measured by the Platelet Function Analyzer® closure time (CT), and the secondary outcomes were serum and plasma thromboxane B2 (sTxB2 and pTxB2). Fifty-four patients (28 females) were included between January 2018 and December 2020. CT was 18% (95%CI 6;32) higher at T3 compared with T1 in the control group (n = 16), whereas sTxB2 and pTxB2 did not differ. Aspirin prolonged CT with 100% (95%CI 77; 127) from T1 to T2 in the intervention group (n = 38), while it increased with only 12% (95%CI 1;25) in controls. sTxB2 decreased with 95% (95%CI - 97; - 92) from T1 to T2, while it increased in the control group. pTxB2 was not affected compared with controls. Platelet aggregation is increased during severe infection, and this can be inhibited by aspirin. Optimisation of the treatment regimen may further diminish the persisting pTxB2 levels that point towards remaining platelet activity. This trial was registered on 13 April 2017 at EudraCT (2016-004303-32).

A Comparative Analysis of Effectiveness of Recombinant Interleukin-11 Versus Papaya Leaf Extract for Treatment of Thrombocytopenia: A Review.

Platelets or thrombocytes play an important role in thrombosis and maintaining hemostasis. Thrombocytes help in forming blood clots at the site of the wound. When the level of platelets decreases, uncontrolled bleeding occurs which can result in mortality. A decrease in the blood platelet level is known as thrombocytopenia which can be caused due to various reasons. A variety of treatment options are available for thrombocytopenia like platelet transfusion, splenectomy, platelet management with various types of corticosteroids, and recombinant interleukin-11 (rhIL-11). The use of rhIL-11 is approved by FDA for the treatment of thrombocytopenia. rhIL-11 is a recombinant cytokine that is administered to patients suffering from chemotherapy-induced thrombocytopenia as it enhances megakaryocytic proliferation which aids in platelet production. But this treatment has various side effects and is costly. Hence, there is a crucial need to identify cost-effective alternative strategies that present no side effects. The majority of the population in low-income countries requires a functional and cost-effective treatment for low thrombocyte count. Carica papaya is a tropical herbaceous plant that has been reported in recovering low platelet count during dengue virus infection. Even though multiple benefits of the Carica papaya leaf extract (CPLE) are popular, the active compound present in it, which mediates these benefits, remains to be identified. This review aims to highlight the different aspects of rhIL-11 and CPLE-induced platelet counts and their limitations and benefits in the treatment of thrombocytopenia. The literature related to the treatment of thrombocytopenia using rhIL-11 and CPLE from 1970 to 2022 was searched using PubMed and Google Scholar databases with the keywords Recombinant Interleukin-11, Papaya Leaf Extract, Thrombocytopenia, and Platelets.

Host Cells of Leucocytozoon (Haemosporida, Leucocytozoidae) Gametocytes, with Remarks on the Phylogenetic Importance of This Character.

Leucocytozoon parasites remain poorly investigated in comparison to other haemosporidians. The host cell inhabited by their blood stages (gametocytes) remains insufficiently known. This study aimed to determine the blood cells inhabited by Leucocytozoon gametocytes in different species of Passeriformes and to test if this feature has a phylogenetic importance. We microscopically analyzed blood films stained with Giemsa from six different bird species and individuals and used PCR-based methods for parasite lineage identification. The DNA sequences obtained were applied for phylogenetic analysis. Leucocytozoon parasite from the song thrush Turdus philomelos (cytochrome b lineage STUR1), the blackbird Turdus merula (undetermined lineage), the garden warbler Sylvia borin (unknown lineage) inhabited erythrocytes, a parasite from the blue tit Cyanistes caeruleus (PARUS4) infects lymphocytes, while in the wood warbler Phylloscopus sibilatrix (WW6) and the common chiffchaff Phylloscopus collybita (AFR205) they were found inhabiting thrombocytes. Parasites infecting thrombocytes were closely related, while the parasites infecting erythrocytes were placed in three different clades, and the one found in lymphocytes was placed in a separate clade. This shows that the determination of host cells inhabited by Leucocytozoon parasites can be phylogenetically important and should be considered in future species descriptions. Noteworthy, phylogenetic analysis might be used for the prediction of which host cells parasite lineages might inhabit.

FcγRIIA-specific DARPins as novel tools in blood cell analysis and platelet aggregation.

Fc receptors are involved in a variety of physiologically and disease-relevant responses. Among them, FcγRIIA (CD32a) is known for its activating functions in pathogen recognition and platelet biology, and, as potential marker of T lymphocytes latently infected with HIV-1. The latter has not been without controversy due to technical challenges complicated by T-B cell conjugates and trogocytosis as well as a lack of antibodies distinguishing between the closely related isoforms of FcγRII. To generate high-affinity binders specific for FcγRIIA, libraries of designed ankyrin repeat proteins (DARPins) were screened for binding to its extracellular domains by ribosomal display. Counterselection against FcγRIIB eliminated binders cross-reacting with both isoforms. The identified DARPins bound FcγRIIA with no detectable binding for FcγRIIB. Their affinities for FcγRIIA were in the low nanomolar range and could be enhanced by cleavage of the His-tag and dimerization. Interestingly, complex formation between DARPin and FcγRIIA followed a two-state reaction model, and discrimination from FcγRIIB was based on a single amino acid residue. In flow cytometry, DARPin F11 detected FcγRIIA+ cells even when they made up less than 1% of the cell population. Image stream analysis of primary human blood cells confirmed that F11 caused dim but reliable cell surface staining of a small subpopulation of T lymphocytes. When incubated with platelets, F11 inhibited their aggregation equally efficient as antibodies unable to discriminate between both FcγRII isoforms. The selected DARPins are unique novel tools for platelet aggregation studies as well as the role of FcγRIIA for the latent HIV-1 reservoir.