Platelet-derived TLT-1 is a prognostic indicator in ALI/ARDS and prevents tissue damage in the lungs in a mouse model

Platelet-derived sTLT-1 is associated with platelet-mediated inflammation in coronary artery disease patients

The development of coronary artery disease (CAD) depends heavily on platelet activation, and inflammation plays a major role in all stages of atherosclerosis. Platelet-specific soluble triggering receptor expressed on myeloid cells like transcript 1 (sTLT-1) facilitate clot formation and have been linked to chronic inflammation. In this study, we explored the role of platelet-derived sTLT-1 in platelet-mediated inflammation in CAD patients. Plasma levels of sTLT-1 were measured using enzyme-linked immunosorbent assay in CAD patients (n = 163) and healthy controls (n = 99). Correlation analysis was performed to determine the circulatory sTLT-1 levels with platelet activation markers, immune cells, and inflammatory cytokines/chemokines. Increased plasma sTLT-1 levels were observed in CAD patients compared with those in healthy controls (p < 0.0001). A positive correlation was observed between sTLT-1 and platelet activation markers (P-selectin, PAC-1), CD14++ CD16- cells (classical monocytes), Natural killer T (NKT) cells, and platelet-immune cell aggregates with monocytes, neutrophils, dendritic cells, CD11c+ cells, and NKT cells. In contrast, a significant negative correlation was observed with CD8 cells. Furthermore, a significant positive correlation was observed between sTLT-1 and inflammatory markers (TNF-α, IL-1β, IL-2, IL-6, IL-12p70, IL-18, CXCL-12, and CCL-11). Logistic regression analysis identified sTLT-1 and triglycerides as predictors of CAD. Receiver operating characteristic curve (ROC) analysis showed that sTLT-1 had a higher sensitivity and specificity for predicting CAD. Our findings suggest that platelet activation induces the release of sTLT-1 into the circulation in CAD patients, which aggregates with immune cells and enhances inflammatory responses.

Shedding light on GPIbα shedding

PURPOSE OF REVIEW

Ectodomain shedding has been investigated since the late 1980s. The abundant and platelet specific GPIbα receptor is cleaved by ADAM17 resulting in the release of its ectodomain called glycocalicin. This review will address the role of glycocalicin as an end-stage marker of platelet turnover and storage lesion and will consider a potential function as effector in processes beyond hemostasis.

RECENT FINDINGS

Glycocalicin has been described as a marker for platelet senescence, turnover and storage lesion but is not routinely used in a clinical setting because its diagnostic value is nondiscriminatory. Inhibition of glycocalicin shedding improves posttransfusion recovery but little is known (yet) about potential hemostatic improvements. In physiological settings, GPIbα shedding is restricted to the intracellular GPIbα receptor subpopulation suggesting a role for shedding or glycocalicin beyond hemostasis.

SUMMARY

So far, all evidence represents glycocalicin as an end-stage biomarker of platelet senescence and a potential trigger for platelet clearance. The extensive list of interaction partners of GPIbα in fields beyond hemostasis opens new possibilities to investigate specific effector functions of glycocalicin.

Orexin A alleviates LPS-induced acute lung injury by inhibiting macrophage activation through JNK-mediated autophagy

Crosstalk between the central nervous system and immune system by the neuroendocrine and autonomic nervous systems is critical during the inflammatory response. Exposure to endotoxin alters the activity of hypothalamic homeostatic systems, resulting in changed transmitter release within the brain. This study investigated the effects and cellular molecular mechanisms of neurogenic and exogenous orexin-A (OXA) in LPS-induced acute lung injury (ALI). We found the production of OXA in the hypothalamus and lungs was both decreased following LPS infection. LPS-induced lung injury including the destruction of the structure, inflammatory cell infiltration, and pro-inflammatory cytokines generation was aggravated in mice in which orexin neurons were lesioned with the neurotoxin orexin-saporin (orexin-SAP). Administration of exogenous OXA greatly improved lung pathology and reduced inflammatory response. Orexin receptors were found in cultured mouse bone marrow-derived macrophages (BMDMs) and lung macrophages (LMs), adoptive transfer of OXA-treated macrophages showed alleviative lung injury compared to adoptive transfer of macrophages without OXA treatment. Mechanistically, it is the induction of autophagy via JNK activation that is responsible for OXA to suppress macrophage-derived pro-inflammatory cytokine production. These findings highlight the importance of neuro-immune crosstalk and indicate that OXA may be a potential therapeutic agent in the treatment of ALI.

Decreased level of TREM like Transcript 1 (TLT-1) is associated with prematurity and promotes the in-utero inflammatory response to maternal lipopolysaccharide (LPS) exposure

PROBLEM

The occurrence of preterm birth is associated with multiple factors including bleeding, infection and inflammation. Platelets are mediators of hemostasis and can modulate inflammation through interactions with leukocytes. TREM like Transcript 1 (TLT-1) is a type 1 single Ig domain receptor on activated platelets. In adults, it plays a protective role by dampening the inflammatory response and facilitating platelet aggregation at sites of vascular injury. TLT-1 is expressed in human placenta and found in cord blood. We thus hypothesized that TLT-1 deficiency is associated with prematurity and fetal inflammation.

METHOD OF STUDY

To test this hypothesis, we examined cord blood levels of soluble TLT-1 (sTLT) in premature and term infants and compared the inflammatory response in C57BL/6 (WT) and TLT-1-/- (treml1-/- , KO) mice given intraperitoneal LPS mid-gestation RESULTS: The preterm infant cord blood level of sTLT was significantly lower than that found at term. On exposure to LPS, histology of KO (as compared to WT) placenta and decidua showed increased hemorrhage, and KO decidual RNA expression of IL-10 was significantly lower. KO fetal interface tissues (placenta, membranes, amniotic fluid) over time showed increased expression of inflammatory cytokines such as IL-6, IFN-γ, and TNF, but not MCP-1. However, fetal organs showed similar levels.

CONCLUSION

There is a potential association between insufficient TLT-1 expression and increased fetal inflammatory responses in the setting of prematurity. The data support further study of TLT-1 in the mechanistic link between bleeding, inflammation and preterm birth, and perhaps as a biomarker in human pregnancy.

The Characterization and Evaluation of the Soluble Triggering Receptor Expressed on Myeloid Cells-like Transcript-1 in Stable Coronary Artery Disease

Platelets play crucial roles in the development and progression of coronary artery disease (CAD). The triggering receptor expressed in myeloid cells-like transcript-1 (TLT-1) is stored in platelet α granules, and activated platelets release a soluble fragment (sTLT-1). We set out to better characterize the constituent amino acids of sTLT-1 and to evaluate sTLT-1 for use as a biomarker in patients with stable CAD. We evaluated sTLT-1 release using immunoprecipitation and mass spectrometry and employed statistical methods to retrospectively correlate sTLT-1 concentrations, utilizing ELISA in plasma samples from 1510 patients with documented stable CAD. We identified TLT-1 residues to 133 in platelet releasates. ADAM17 cuts TLT-1, suggesting that S136 is the C-terminal amino acid in sTLT-1. Our results revealed that for CAD patients, sTLT-1 levels did not differ significantly according to primary outcomes of death or major cardiac event; however, patients with left ventricular (LV) dysfunction had significantly lower plasma sTLT-1 levels as compared to those with normal LV function (981.62 ± 1141 pg/mL vs. 1247.48 ± 1589 pg/mL; p = 0.003). When patients were stratified based on sTLT-1 peak frequency distribution (544 pg/mL), a significant association with congestive heart failure was identified (OR = 2.94; 1.040-8.282; p = 0.042), which could be explained by LV dysfunction.

The biology of TREM receptors

Triggering receptors expressed on myeloid cells (TREMs) encompass a family of cell-surface receptors chiefly expressed by granulocytes, monocytes and tissue macrophages. These receptors have been implicated in inflammation, neurodegenerative diseases, bone remodelling, metabolic syndrome, atherosclerosis and cancer. Here, I review the structure, ligands, signalling modes and functions of TREMs in humans and mice and discuss the challenges that remain in understanding TREM biology.

A NETWORK PHARMACOLOGY-BASED TREATMENT ANALYSIS OF LUTEOLIN FOR REGULATING PYROPTOSIS IN ACUTE LUNG INJURY

ABSTRACT

Background: Acute lung injury (ALI) and its severe manifestation, acute respiratory distress syndrome, are complicated pulmonary inflammatory conditions for which standard therapeutics are still not well established. Although increasing research has indicated the anti-inflammatory, anticancer, and antioxidant effects of luteolin, especially in lung diseases, the molecular mechanisms underlying luteolin treatment remain largely unclear. Methods: The potential targets of luteolin in ALI were explored using a network pharmacology-based strategy and further validated in a clinical database. The relevant targets of luteolin and ALI were first obtained, and the key target genes were analyzed using a protein-protein interaction network, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. The targets of luteolin and ALI were then combined to ascertain the relevant pyroptosis targets, followed by Gene Ontology analysis of core genes and molecular docking of key active compounds to the antipyroptosis targets of luteolin in resolving ALI. The expression of the obtained genes was verified using the Gene Expression Omnibus database. In vivo and in vitro experiments were performed to explore the potential therapeutic effects and mechanisms of action of luteolin against ALI. Results: Fifty key genes and 109 luteolin pathways for ALI treatment were identified through network pharmacology. Key target genes of luteolin for treating ALI via pyroptosis were identified. The most significant target genes of luteolin in ALI resolution included AKT1, NOS2, and CTSG. Compared with controls, patients with ALI had lower AKT1 expression and higher CTSG expression. Luteolin simply reduced systemic inflammation and lung tissue damage in septic mice. Furthermore, we blocked AKT1 expression and found luteolin reduced the degree of lung injury and affected NOS2 levels. Conclusions: As demonstrated by a network pharmacology approach, luteolin may exert an antipyroptosis effect on ALI via AKT1, NOS2, and CTSG.

Novel Aspects Targeting Platelets in Atherosclerotic Cardiovascular Disease—A Translational Perspective

Platelets are important cellular targets in cardiovascular disease. Based on insights from basic science, translational approaches and clinical studies, a distinguished anti-platelet drug treatment regimen for cardiovascular patients could be established. Furthermore, platelets are increasingly considered as cells mediating effects “beyond thrombosis”, including vascular inflammation, tissue remodeling and healing of vascular and tissue lesions. This review has its focus on the functions and interactions of platelets with potential translational and clinical relevance. The role of platelets for the development of atherosclerosis and therapeutic modalities for primary and secondary prevention of atherosclerotic disease are addressed. Furthermore, novel therapeutic options for inhibiting platelet function and the use of platelets in regenerative medicine are considered.

Whole Blood Transfusion for Severe Malarial Anemia in a High Plasmodium falciparum Transmission Setting

BACKGROUND

Severe malaria resulting from Plasmodium falciparum infection is the leading parasitic cause of death in children worldwide, and severe malarial anemia (SMA) is the most common clinical presentation. The evidence in support of current blood transfusion guidelines for patients with SMA is limited.

METHODS

We conducted a retrospective cohort study of 911 hospitalized children with SMA in a holoendemic region of Zambia to examine the association of whole blood transfusion with in-hospital survival. Data were analyzed in adjusted logistic regression models using multiple imputation for missing data.

RESULTS

The median age of patients was 24 months (interquartile range, 16-30) and overall case fatality was 16%. Blood transfusion was associated with 35% reduced odds of death in children with SMA (odds ratio, 0.65; 95% confidence interval, .52-.81; P = .0002) corresponding to a number-needed-to-treat (NNT) of 14 patients. Children with SMA complicated by thrombocytopenia were more likely to benefit from transfusion than those without thrombocytopenia (NNT = 5). Longer storage time of whole blood was negatively associated with survival and with the posttransfusion rise in the platelet count but was not associated with the posttransfusion change in hemoglobin concentration.

CONCLUSIONS

Whole blood given to pediatric patients with SMA was associated with improved survival, mainly among those with thrombocytopenia who received whole blood stored for <4 weeks. These findings point to a potential use for incorporating thrombocytopenia into clinical decision making and management of severe malaria, which can be further assessed in prospective studies, and underline the importance of maintaining reliable blood donation networks in areas of high malaria transmission.

Platelet in thrombo-inflammation: Unraveling new therapeutic targets

In the broad range of human diseases, thrombo-inflammation appears as a clinical manifestation. Clinically, it is well characterized in context of superficial thrombophlebitis that is recognized as thrombosis and inflammation of superficial veins. However, it is more hazardous when developed in the microvasculature of injured/inflamed/infected tissues and organs. Several diseases like sepsis and ischemia-reperfusion can cause formation of microvascular thrombosis subsequently leading to thrombo-inflammation. Thrombo-inflammation can also occur in cases of antiphospholipid syndrome, preeclampsia, sickle cell disease, bacterial and viral infection. One of the major contributors to thrombo-inflammation is the loss of normal anti-thrombotic and anti-inflammatory potential of the endothelial cells of vasculature. This manifest itself in the form of dysregulation of the coagulation pathway and complement system, pathologic platelet activation, and increased recruitment of leukocyte within the microvasculature. The role of platelets in hemostasis and formation of thrombi under pathologic and non-pathologic conditions is well established. Platelets are anucleate cells known for their essential role in primary hemostasis and the coagulation pathway. In recent years, studies provide strong evidence for the critical involvement of platelets in inflammatory processes like acute ischemic stroke, and viral infections like Coronavirus disease 2019 (COVID-19). This has encouraged the researchers to investigate the contribution of platelets in the pathology of various thrombo-inflammatory diseases. The inhibition of platelet surface receptors or their intracellular signaling which mediate initial platelet activation and adhesion might prove to be suitable targets in thrombo-inflammatory disorders. Thus, the present review summarizes the concept and mechanism of platelet signaling and briefly discuss their role in sterile and non-sterile thrombo-inflammation, with the emphasis on role of platelets in COVID-19 induced thrombo-inflammation. The aim of this review is to summarize the recent developments in deciphering the role of the platelets in thrombo-inflammation and discuss their potential as pharmaceutical targets.

ASIC1a induces mitochondrial apoptotic responses in acute lung injury

AIM

This study aimed to investigate the promoting effect of acid-sensing ion channel 1a (ASIC1a) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and its mechanisms.

METHODS

In this experiment, the ALI rat model was induced by intratracheal injection of LPS, and the ASIC1a specific blocker psalmotoxin-1 (PcTx-1) was injected into the tail vein before LPS administration once. Western blot, immunofluorescence, immunohistochemistry and real-time PCR methods were used to detect ASIC1a and apoptosis-related proteins expressions in lung tissue and RLE-6TN rat type II alveolar epithelial cells. Confocal Laser Scanning Microscopy was used to detect Ca²⁺ fluorescence intensity in RLE-6TN cells.

RESULTS

PcTx-1 pretreatment not only inhibited the pathological changes of LPS-induced ALI in lung tissue, but also inhibited lung dysfunction. PcTx-1 also reduced the increased levels of the apoptosis-related proteins B-cell lymphoma-2-associated X (Bax) and cleaved cysteinyl aspartate specific proteinase 3 (Cleaved caspase-3) and increased the decreased level of B-cell lymphoma-2 (Bcl-2) in the lung tissue of the model group. LPS-induced changes in mitochondrial membrane potential and calcium influx in alveolar epithelial cells were also reversed by PcTx-1.

CONCLUSION

ASIC1a induces an apoptotic response in ALI through mitochondrial apoptosis.

Platelet Count in Patients with SARS-CoV-2 Infection: A Prognostic Factor in COVID-19

COVID-19 patients may manifest thrombocytopenia and some of these patients succumb to infection due to coagulopathy. The aim of our study was to examine platelet count values in patients infected with SARS-CoV-2, comparing them to a control group consisting of non-COVID-19 patients. Moreover, we evaluated the correlation between the platelet value and the respiratory alteration parameters and the outcome (hospitalization and mortality) in COVID-19 patients. The mean platelet values (×109/L) differed between patients with positive or negative SARS-CoV-2 swabs (242.1 ± 92.1 in SARS-CoV-2 negative vs. 215.2 ± 82.8 in COVID-19 patients, p < 0.001). In COVID-19 patients, the platelet count correlated with the A-aO2 gradient (p = 0.001, rho = −0.149), with its increase over the expected (p = 0.013; rho = −0.115), with the PaO2 values (p = 0.036; rho = 0.093), with the PCO2 values (p = 0.003; rho = 0.134) and with the pH values (p = 0.016; rho = −0.108). In COVID-19 negative patients, the platelet values correlated only with the A-aO2 gradient: (p = 0.028; rho = −0.101). Patients discharged from emergency department had a mean platelet value of 234.3 ± 68.7, those hospitalized in ordinary wards had a mean value of 204.3 ± 82.5 and in patients admitted to sub-intensive/intensive care, the mean value was 201.7 ± 75.1. In COVID-19 patients, the survivors had an average platelet value at entry to the emergency department of 220.1 ± 81.4, while that of those who died was 206.4 ± 87.7. Our data confirm that SARS-CoV-2 infection may induce thrombocytopenia, and that the reduction in platelet counts could be correlated with the main blood gas parameters and with clinical outcome; as a consequence, platelet count could be an important prognostic factor to evaluate and stratify COVID-19 patients.

Characterization of Platelet Biologic Markers in the Early Pathogenesis of Postoperative Acute Respiratory Distress Syndrome

Animal models and limited human studies have suggested a plausible role for platelets in the pathogenesis and resolution of acute respiratory distress syndrome (ARDS). However, there are little data regarding the role of platelets in ARDS development.

OBJECTIVES

The objective of this study was to characterize the role of platelets in a postoperative ARDS model through an analysis of two platelet-specific biologic markers: thromboxane A₂ (TxA₂) and soluble CD-40-ligand (sCD40L).

DESIGN SETTING AND PARTICIPANTS

This was a nested case-control study of ARDS cases matched to non-ARDS controls. Blood samples were collected from a cohort of 500 patients undergoing thoracic, aortic vascular, or cardiac surgery that placed them at high-risk of developing postoperative ARDS.

MAIN OUTCOMES AND MEASURES

TxA₂ and sCD40L were analyzed at baseline (prior to surgical incision) as well as 2 hours and 6 hours after the key intraoperative events believed to be associated with increased risk of postoperative ARDS.

RESULTS

Of 500 patients enrolled, 20 ARDS cases were matched 1:2 to non-ARDS controls based on age, sex, surgical procedure, and surgical lung injury prediction score. Those who developed ARDS had longer surgeries, greater fluid administration, and higher peak inspiratory pressures. There were no significant differences in levels of TxA₂ or sCD40L at baseline, at 2 hours, or at 6 hours. There was also no difference in the change in biomarker concentration between baseline and 2 hours or baseline and 6 hours.

CONCLUSIONS

Two novel platelet-associated biologic markers (TxA₂ and sCD40L) were not elevated in patients who developed ARDS in a postoperative ARDS model. Although limited by the relatively small study size, these results do not support a clear role for platelets in the early pathogenesis of postoperative ARDS.

Platelet Versus Megakaryocyte: Who Is the Real Bandleader of Thromboinflammation in Sepsis?

Platelets are mainly known for their key role in hemostasis and thrombosis. However, studies over the last two decades have shown their strong implication in mechanisms associated with inflammation, thrombosis, and the immune system in various neoplastic, inflammatory, autoimmune, and infectious diseases. During sepsis, platelets amplify the recruitment and activation of innate immune cells at the site of infection and contribute to the elimination of pathogens. In certain conditions, these mechanisms can lead to thromboinflammation resulting in severe organ dysfunction. Here, we discuss the interactions of platelets with leukocytes, neutrophil extracellular traps (NETs), and endothelial cells during sepsis. The intrinsic properties of platelets that generate an inflammatory signal through the NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome are discussed. As an example of immunothrombosis, the implication of platelets in vaccine-induced immune thrombotic thrombocytopenia is documented. Finally, we discuss the role of megakaryocytes (MKs) in thromboinflammation and their adaptive responses.

TLT-1 Promotes Platelet-Monocyte Aggregate Formation to Induce IL-10-Producing B Cells in Tuberculosis

The immunoregulation of platelets and platelet-monocyte aggregates (PMAs) is increasingly recognized, but it roles in tuberculosis (TB) remain to be elucidated. In this study, we found that CD14⁺CD41⁺ PMAs were increased in peripheral blood of patients with active TB. CD14⁺CD41⁺ PMAs highly expressed triggering receptors expressed on myeloid cells (TREMs)-like transcript-1 (TLT-1), P-selectin (CD62P), and CD40L. Our in vitro study found that platelets from patients with active TB aggregate with monocytes to induce IL-1β and IL-6 production by monocytes. Importantly, we identified that TLT-1 was required for formation of PMAs. The potential TLT-1 ligand was expressed and increased on CD14⁺ monocytes of patients with TB determined by using TLT-1 fusion protein (TLT-1 Fc). Blocking of ligand-TLT-1 interaction with TLT-1 Fc reduced PMA formation and IL-1β and IL-6 production by monocytes. Further results demonstrated that PMAs induced IL-10 production by B cells (B10) dependent on IL-1β, IL-6, and CD40L signals in a coculture system. Moreover, TLT-1 Fc treatment suppressed B10 polarization via blocking PMA formation. Taking all of these data together, we elucidated that TLT-1 promoted PMA-mediated B10 polarization through enhancing IL-1β, IL-6, and CD40L origin from PMAs, which may provide potential targeting strategies for TB disease treatment.

Release of α-granule contents during platelet activation

Upon activation, platelets release a plethora of factors which help to mediate their dynamic functions in hemostasis, inflammation, wound healing, tumor metastasis and angiogenesis. The majority of these bioactive molecules are released from α-granules, which are unique to platelets, and contain an incredibly diverse repertoire of cargo including; integral membrane proteins, pro-coagulant molecules, chemokines, mitogenic, growth and angiogenic factors, adhesion proteins, and microbicidal proteins. Clinically, activation of circulating platelets has increasingly been associated with various disease states. Biomarkers indicating the level of platelet activation in patients can therefore be useful tools to evaluate risk factors to predict future complications and determine treatment strategies or evaluate antiplatelet therapy. The irreversible nature of α-granule secretion makes it ideally suited as a marker of platelet activation. This review outlines the release and contents of platelet α-granules, as well as the membrane bound, and soluble α-granule cargo proteins that can be used as biomarkers of platelet activation.

Immunohistochemical diagnosis of the viability of the strangulation furrow

The aim of the research was to study the possibility of using immunohistochemical markers for the diagnosis of intravital stangulation. Materials and methods: Fragments of the neck skin from the strnaglulation zone were selected as objects of research. The main study group included 20 deaths due to hanging (10 men and 10 women). For the control group, 10 cases of acute coronary death (5 men and 5 women) were used. Using a complex of IHC markers, the labeling of the epidermis and epithelial structures, the features of cellular immune responses, the manifestation of oxidative steress were studied. Results: Peculiarities of morphological manifestations of strangulation furrow in mechanical asphyxia were studied. It is established that the key link of its morphogenesis is impaired vascular wall permeability with loss of type IV collagen in the basement membranes of epithelium and skin vessels, migration into tissues of activated CD15+ granulocytes, CD68+ macrophages and CD117+ labrocytes, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), fibrinogen protein and transforming growth factor β1. Conclusion: Such changes in the tinctorial properties of skin and subcutaneous adipose tissue can be recorded by immunohistochemical (IHC) and serve as an important diagnostic criterion for the viability of the formation of the strangulation furrow.

DIA proteomics analysis through serum profiles reveals the significant proteins as candidate biomarkers in women with PCOS

Background

The aim of this study was to apply proteomic methodology for the analysis of proteome changes in women with polycystic ovary syndrome (PCOS).

Material and methods

All the participators including 31 PCOS patients and 31 healthy female as controls were recruited, the clinical characteristics data was recorded at the time of recruitment, the laboratory biochemical data was detected. Then, a data-independent acquisition (DIA)-based proteomics method was performed to compare the serum protein changes between PCOS patients and controls. In addition, Western blotting was used to validate the expression of identified proteomic biomarkers.

Results

There were 80 proteins differentially expressed between PCOS patients and controls significantly, including 54 downregulated and 26 upregulated proteins. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis showed that downregulated proteins were enriched in platelet degranulation, cell adhesion, cell activation, blood coagulation, hemostasis, defense response and inflammatory response terms; upregulated proteins were enriched in cofactor catabolic process, hydrogen peroxide catabolic process, antioxidant activity, cellular oxidant detoxification, cellular detoxification, antibiotic catabolic process and hydrogen peroxide metabolic process. Receiver operating characteristic curves analysis showed that the area under curve of Histone H4 (H4), Histone H2A (H2A), Trem-like transcript 1 protein (TLT-1) were all over than 0.9, indicated promising diagnosis values of these proteins. Western blotting results proved that the detected significant proteins, including H4, H2A, TLT-1, Peroxiredoxin-1, Band 3 anion transport protein were all differently expressed in PCOS and control groups significantly.

Conclusion

These proteomic biomarkers provided the potentiality to help us understand PCOS better, but future studies comparing systemic expression and exact role of these candidate biomarkers in PCOS are essential for confirmation of this hypothesis.

The enigmatic nature of the triggering receptor expressed in myeloid cells -1 (TLT- 1)

Receptors are important pharmacological targets on cells. The Triggering Receptor Expressed on Myeloid Cells (TREM) - Like Transcript - 1 is an abundant, yet little understood, platelet receptor. It is a single Ig domain containing receptor isolated in the α-granules of resting platelets and brought to the platelet surface upon activation. On platelets, the integrin αIIbβ3 is the major receptor having roughly 80,000 copies. αIIbβ3 is a heterodimeric multidomain structure that mediates platelet aggregation through its interaction with the plasma protein fibrinogen. Anti-platelet drugs have successfully targeted αIIbβ3 to control thrombosis. Like αIIbβ3, TLT-1 also binds fibrinogen, making its role in platelet function somewhat obscure. In this review, we highlight the known structural features of TLT-1 and present the challenges of understanding TLT-1 function. In our analysis of the dynamics of the platelet surface after activation we propose a model in which TLT-1 supports αIIbβ3 function as a mechanoreceptor that may direct platelets toward immune function.

Effects of melatonin on protecting against lung injury (Review)

Melatonin (MT; N-acetyl-5-methoxy-tryptamine), which has multiple effects and roles, is secreted from the pineal gland at night according to the daily rhythm. In addition to circadian regulation, MT has anti-inflammatory, antioxidant and anticancer functions. Recent studies postulated that MT serves a critical role in apoptosis, anti-ischemic reperfusion injury and anti-proliferative effects on various cells. The current review reported on the underlying mechanism behind the protective effect of MT on lung diseases, such as acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, lung ischemia-reperfusion injury, sepsis-induced lung injury and ventilator-induced lung injury. MT is considered an adjuvant with therapeutic drugs for preventing inflammation and is responsible for regulating patient sleep cycles in the intensive care unit. The current review described the anti-inflammatory and antioxidant efficiency of MT with a focus on the molecular mechanisms of action in various lung injuries.

Platelets as key players in inflammation and infection

PURPOSE OF REVIEW

This review highlights recent insights into the role of platelets in acute inflammation and infection.

RECENT FINDINGS

Platelets exhibit intravascular crawling behavior and can collect and bundle bacteria. In addition, platelets are key in promoting intravascular thrombus formation in infection, a process termed 'immunothrombosis', which contributes to pathogen containment, but also potentially damages the host. Platelets are at the nexus of leukocyte recruitment and activation, yet they are at the same time crucial in preventing inflammation-associated hemorrhage and tissue damage. This multitasking requires specific receptors and pathways, depending on stimulus, organ and effector function.

SUMMARY

New findings highlight the complex interplay of innate immunity, coagulation and platelets in inflammation and infection, and unravel novel molecular pathways and effector functions. These offer new potential therapeutic approaches, but require further extensive research to distinguish treatable proinflammatory from host-protective pathways.

Low-soluble TREM-like transcript-1 levels early after severe burn reflect increased coagulation disorders and predict 30-day mortality

BACKGROUND

Patients with severe burns often show systemic coagulation changes in the early stage and even develop extensive coagulopathy. Previous studies have confirmed that soluble TREM-like transcript-1 (sTLT-1) mediates a novel mechanism of haemostasis and thrombosis in inflammatory vascular injury. At present, the role of sTLT-1 in patients with severe burns is not well known.

OBJECTIVE

To investigate the early association between sTLT-1 levels and markers of burn severity, coagulation disorders, endothelial permeability, shock and prognosis in patients with severe burns.

METHODS

A prospective, observational study was conducted with 60 severe burn patients (divided into a death group and a survival group according to 30-day prognosis) admitted to our hospital. Twenty-eight healthy volunteers were recruited as the control group. Blood components at 48 h after burn were analysed for sTLT-1 and biomarkers reflecting platelet activation, shock, endothelial glycocalyx damage, capillary leakage, haemostasis, fibrinolytic activity, natural anticoagulation and blood cells. We compared the three groups, analysed the correlation between sTLT-1 and biomarkers, and investigated the predictive value of sTLT-1 for 30-day prognosis.

RESULT

Compared with the surviving patients, the patients who died had a lower degree of platelet activation [lower sTLT-1, platelet factor 4 (PF-4) and platelet counts] and a higher degree of burn [higher abbreviated burn severity index score (ABSI score)], shock (higher lactate), endothelial glycocalyx damage [higher syndecan-1 and soluble thrombomodulin (sTM)] and capillary leakage [higher resuscitation fluid (0-48 h), lower albumin] as well as decreased haemostasis [higher activated partial prothrombin time (APTT), lower fibrinogen and thrombin-antithrombin III complex (TAT)], increased fibrinolytic activity [higher D-dimer and tissue-type plasminogen activator (tPA)] and decreased natural anticoagulation [lower protein C (PC) and protein S (PS)]. Higher D-dimer (P = 0.013) and lower PF-4 (P = 0.001) were significantly independently associated with lower sTLT-1. Low circulating sTLT-1 (a unit is 50 pg/mL) (odds ratio [OR] 2.08 [95% CI 1.11-3.92], P = 0.022) was an independent predictor of increased 30-day mortality.

CONCLUSION

Low sTLT-1 levels at 48 h after burn in patients with severe burns is associated with increased coagulation disorders. Low circulating sTLT-1 levels were an independent predictor of increased 30-day mortality.

Endothelial cells, neutrophils and platelets: getting to the bottom of an inflammatory triangle

Severe fibrotic and thrombotic events permeate the healthcare system, causing suffering for millions of patients with inflammatory disorders. As late-state consequences of chronic inflammation, fibrosis and thrombosis are the culmination of pathological interactions of activated endothelium, neutrophils and platelets after vessel injury. Coupling of these three cell types ensures a pro-coagulant, cytokine-rich environment that promotes the capture, activation and proliferation of circulating immune cells and recruitment of key pro-fibrotic cell types such as myofibroblasts. As the first responders to sterile inflammatory injury, it is important to understand how endothelial cells, neutrophils and platelets help create this environment. There has been a growing interest in this intersection over the past decade that has helped shape the development of therapeutics to target these processes. Here, we review recent insights into how neutrophils, platelets and endothelial cells guide the development of pathological vessel repair that can also result in underlying tissue fibrosis. We further discuss recent efforts that have been made to translate this knowledge into therapeutics and provide perspective as to how a compound or combination therapeutics may be most efficacious when tackling fibrosis and thrombosis that is brought upon by chronic inflammation.

Antiplatelet Therapy for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a common and devastating syndrome that contributes to serious morbidities and mortality in critically ill patients. No known pharmacologic therapy is beneficial in the treatment of ARDS, and the only effective management is through a protective lung strategy. Platelets play a crucial role in the pathogenesis of ARDS, and antiplatelet therapy may be a potential medication for ARDS. In this review, we introduce the overall pathogenesis of ARDS, and then focus on platelet-related mechanisms underlying the development of ARDS, including platelet adhesion to the injured vessel wall, platelet-leukocyte-endothelium interactions, platelet-related lipid mediators, and neutrophil extracellular traps. We further summarize antiplatelet therapy, including aspirin, glycoprotein IIb/IIIa receptor antagonists, and P2Y12 inhibitors for ARDS in experimental and clinical studies and a meta-analysis. Novel aspirin-derived agents, aspirin-triggered lipoxin, and aspirin-triggered resolvin D1 are also described here. In this narrative review, we summarize the current knowledge of the role of platelets in the pathogenesis of ARDS, and the potential benefits of antiplatelet therapy for the prevention and treatment of ARDS.

The abnormalities of coagulation and fibrinolysis in acute lung injury caused by gas explosion

Acute lung injury (ALI) caused by gas explosion is common, and warrants research on the underlying mechanisms. Specifically, the role of abnormalities of coagulation and fibrinolysis in this process has not been defined. It was hypothesized that the abnormal coagulation and fibrinolysis promoted ALI caused by gas explosion. Based on the presence of ALI, 74 cases of gas explosion injury were divided into the ALI and non-ALI groups. The results of prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), and platelet count (PLT) were collected within 24 hours and compared between the groups. ALI models caused by gas explosion were established in Sprague Dawley rats, and injuries were evaluated using hematoxylin and eosin (HE) staining and histopathological scoring. Moreover, the bronchoalveolar lavage fluid (BALF) was collected to examine thrombin-antithrombin complex (TAT), tissue factor (TF), tissue factor pathway inhibitor (TFPI), and plasminogen activator inhibitor-1 (PAI-1) levels by enzyme-linked immunosorbent assay (ELISA). The patients in ALI group had shorter PT and longer APTT, raised concentration of FIB and decreased number of PLT, as compared to the non-ALI group. In ALI rats, the HE staining revealed red blood cells in alveoli and interstitial thickening within 2 hours which peaked at 72 hours. The levels of TAT/TF in the BALF increased continually until the seventh day, while the PAI-1 was raised after 24 hours and 7 days. The TFPI was elevated after 2 hours and 24 hours, and then decreased after 72 hours. Abnormalities in coagulation and fibrinolysis in lung tissues play a role in ALI caused by gas explosion.

Necrostatin‑1 protects mice from acute lung injury by suppressing necroptosis and reactive oxygen species

Acute lung injury (ALI) is characterized by tissue damage and inflammatory cytokine secretion; however, the therapeutic options available to treat ALI remain limited. Necrostatin-1 (Nec-1) has the ability to attenuate cell necroptosis in various inflammatory diseases. The present study evaluated the protective effects of Nec-1 on a mouse model of lipopolysaccharide-induced ALI. Histological alterations in the lungs were evaluated through hematoxylin and eosin staining, and the expression levels of cytokines in the bronchoalveolar lavage fluid and lung tissues were determined by ELISA. In addition, accumulated production of reactive oxygen species was determined by staining with DCFH-DA probes, western blotting and immunofluorescence. The results revealed that treatment with the necroptosis inhibitor, Nec-1, exerted significant protective effects on ALI-induced inflammation and necroptosis. The key proteins involved in necroptosis were markedly reduced, including receptor-interacting serine/threonine-protein kinase (RIP)1 and RIP3. Notably, antioxidant proteins were upregulated by Nec-1, which may attenuate oxidative stress. Furthermore, treatment with Nec-1 markedly suppressed necroptosis in the pulmonary alveoli RLE-6TN cell line. Taken together, these data revealed a novel association between ALI and necroptosis, and suggested that necroptosis inhibitors may be used as effective anti-inflammatory drugs to treat ALI.

Platelet biology of the rapidly failing lung

Acute respiratory distress syndrome (ARDS) is characterized by a rapid-onset respiratory failure with a mortality rate of approximately 40%. This physiologic inflammatory process is mediated by disruption of the alveolar-vascular interface, leading to pulmonary oedema and impaired oxygen exchange, which often warrants mechanical ventilation to increase survival in the acute setting. One of the least understood aspects of ARDS is the role of the platelets in this process. Platelets, which protect vascular integrity, play a pivotal role in the progression and resolution of ARDS. The recent substantiation of the age-old theory that megakaryocytes are found in the lungs has rejuvenated interest in and raised new questions about the importance of platelets for pulmonary function. In addition to primary haemostasis, platelets provide a myriad of inflammatory functions that are poised to aid the innate immune system. This review focuses on the evidence for regulatory roles of platelets in pulmonary inflammation, with an emphasis on two receptors, CLEC-2 and TLT-1. Studies of these receptors identify novel pathways through which platelets may regulate vascular integrity and inflammation in the lungs, thereby influencing the development of ARDS.

Thromboinflammation: challenges of therapeutically targeting coagulation and other host defense mechanisms

Thrombosis with associated inflammation (thromboinflammation) occurs commonly in a broad range of human disorders. It is well recognized clinically in the context of superficial thrombophlebitis (thrombosis and inflammation of superficial veins); however, it is more dangerous when it develops in the microvasculature of injured tissues and organs. Microvascular thrombosis with associated inflammation is well recognized in the context of sepsis and ischemia-reperfusion injury; however, it also occurs in organ transplant rejection, major trauma, severe burns, the antiphospholipid syndrome, preeclampsia, sickle cell disease, and biomaterial-induced thromboinflammation. Central to thromboinflammation is the loss of the normal antithrombotic and anti-inflammatory functions of endothelial cells, leading to dysregulation of coagulation, complement, platelet activation, and leukocyte recruitment in the microvasculature. α-Thrombin plays a critical role in coordinating thrombotic and inflammatory responses and has long been considered an attractive therapeutic target to reduce thromboinflammatory complications. This review focuses on the role of basic aspects of coagulation and α-thrombin in promoting thromboinflammatory responses and discusses insights gained from clinical trials on the effects of various inhibitors of coagulation on thromboinflammatory disorders. Studies in sepsis patients have been particularly informative because, despite using anticoagulant approaches with different pharmacological profiles, which act at distinct points in the coagulation cascade, bleeding complications continue to undermine clinical benefit. Future advances may require the development of therapeutics with primary anti-inflammatory and cytoprotective properties, which have less impact on hemostasis. This may be possible with the growing recognition that components of blood coagulation and platelets have prothrombotic and proinflammatory functions independent of their hemostatic effects.

Downregulation of TREM-like transcript-1 and collagen receptor α2 subunit, two novel RUNX1-targets, contributes to platelet dysfunction in familial platelet disorder with predisposition to acute myelogenous leukemia

Germline RUNX1 mutations lead to thrombocytopenia and platelet dysfunction in familial platelet disorder with predisposition to acute myelogenous leukemia (AML). Multiple aspects of platelet function are impaired in these patients, associated with altered expression of genes regulated by RUNX1. We aimed to identify RUNX1-targets involved in platelet function by combining transcriptome analysis of patient and shRUNX1-transduced megakaryocytes (MK). Down-regulated genes included TREM-like transcript (TLT)-1 (TREML1) and the integrin subunit alpha (α)-2 (ITGA2) of collagen receptor α2-beta (β)-1, which are involved in platelet aggregation and adhesion, respectively. RUNX1 binding to regions enriched for H3K27Ac marks was demonstrated for both genes using chromatin immunoprecipitation. Cloning of these regions upstream of the respective promoters in lentivirus allowing mCherry reporter expression showed that RUNX1 positively regulates TREML1 and ITGA2, and this regulation was abrogated after deletion of RUNX1 sites. TLT-1 content was reduced in patient MK and platelets. A blocking anti-TLT-1 antibody was able to block aggregation of normal but not patient platelets, whereas recombinant soluble TLT-1 potentiated fibrinogen binding to patient platelets, pointing to a role for TLT-1 deficiency in the platelet function defect. Low levels of α2 integrin subunit were demonstrated in patient platelets and MK, coupled with reduced platelet and MK adhesion to collagen, both under static and flow conditions. In conclusion, we show that gene expression profiling of RUNX1 knock-down or mutated MK provides a suitable approach to identify novel RUNX1 targets, among which downregulation of TREML1 and ITGA2 clearly contribute to the platelet phenotype of familial platelet disorder with predisposition to AML.