Plasmin-induced expression of cytokines and tissue factor in human monocytes involves AP-1 and IKKbeta-mediated NF-kappaB activation

Bivariate genome-wide association study of circulating fibrinogen and C-reactive protein levels

BACKGROUND

Fibrinogen and C-reactive protein (CRP) play an important role in inflammatory pathways and share multiple genetic loci reported in previously published genome-wide association studies (GWAS), highlighting their common genetic background. Leveraging the shared biology may identify further loci pleiotropically associated with both fibrinogen and CRP.

OBJECTIVES

To identify novel genetic variants that are pleiotropic and associated with both fibrinogen and CRP, by integrating both phenotypes in a bivariate GWAS by using a multitrait GWAS.

METHODS

We performed a bivariate GWAS to identify further pleiotropic genetic loci, using summary statistics of previously published GWAS on fibrinogen (n = 120 246) from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium, consisting of European ancestry samples and CRP (n = 363 228) from UK Biobank, including 5 different population groups. The main analysis was performed using metaUSAT and N-GWAMA. We conducted replication for novel CRP associations to test the robustness of the findings using an independent GWAS for CRP (n = 148 164). We also performed colocalization analysis to compare the associations in identified loci for the 2 traits and Genotype-Tissue Expression data.

RESULTS

We identified 87 pleiotropic loci that overlapped between metaUSAT and N-GWAMA, including 23 previously known for either fibrinogen or CRP, 58 novel loci for fibrinogen, and 6 novel loci for both fibrinogen and CRP. Overall, there were 30 pleiotropic and novel loci for both traits, and 7 of these showed evidence of colocalization, located in or near ZZZ3, NR1I2, RP11-72L22.1, MICU1, ARL14EP, SOCS2, and PGM5. Among these 30 loci, 13 replicated for CRP in an independent CRP GWAS.

CONCLUSION

Bivariate GWAS identified additional associated loci for fibrinogen and CRP. This analysis suggests fibrinogen and CRP share a common genetic architecture with many pleiotropic loci.

Tranexamic acid: a narrative review of its current role in perioperative medicine and acute medical bleeding

Purpose

Tranexamic acid (TXA) is the most widely prescribed antifibrinolytic for active bleeding or to prevent surgical bleeding. Despite numerous large multi-center randomized trials involving thousands of patients being conducted, TXA remains underutilized in indications where it has demonstrated efficacy and a lack of harmful effects. This narrative review aims to provide basic concepts about fibrinolysis and TXA's mode of action and is focused on the most recent and important trials evaluating this drug in different hemorrhagic situations.

Methods

We selected every low bias RCT, and we highlighted their strengths and limitations throughout this review.

Principal findings

While TXA appears to have a favorable benefit-risk ratio in most situations (trauma, obstetrics, at-risk for bleeding surgeries) evidence of benefit is lacking in certain medical settings (SAH, digestive bleeding).

Conclusion

Although in some situations the drug's effect on significant outcomes is modest, its favorable safety profile allows it to be recommended for trauma patients, in obstetrics, and in scheduled surgeries at risk of bleeding. However, it cannot be recommended in cases of spontaneous intracranial bleeding, subarachnoid hemorrhage (SAH), or gastrointestinal bleeding.

The emerging role of tranexamic acid and its principal target, plasminogen, in skeletal health

The worldwide burden of skeletal diseases such as osteoporosis, degenerative joint disease and impaired fracture healing is steadily increasing. Tranexamic acid (TXA), a plasminogen inhibitor and anti-fibrinolytic agent, is used to reduce bleeding with high effectiveness and safety in major surgical procedures. With its widespread clinical application, the effects of TXA beyond anti-fibrinolysis have been noticed and prompted renewed interest in its use. Some clinical trials have characterized the effects of TXA on reducing postoperative infection rates and regulating immune responses in patients undergoing surgery. Also, several animal studies suggest potential therapeutic effects of TXA on skeletal diseases such as osteoporosis and fracture healing. Although a direct effect of TXA on the differentiation and function of bone cells in vitro was shown, few mechanisms of action have been reported. Here, we summarize recent findings of the effects of TXA on skeletal diseases and discuss the underlying plasminogen-dependent and -independent mechanisms related to bone metabolism and the immune response. We furthermore discuss potential novel indications for TXA application as a treatment strategy for skeletal diseases.

The Roles of Fibrinolytic Factors in Bone Destruction Caused by Inflammation

Chronic inflammatory diseases, such as rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus, Crohn's disease, periodontitis, and carcinoma metastasis frequently result in bone destruction. Pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-17 are known to influence bone loss by promoting the differentiation and activation of osteoclasts. Fibrinolytic factors, such as plasminogen (Plg), plasmin, urokinase-type plasminogen activator (uPA), its receptor (uPAR), tissue-type plasminogen activator (tPA), α2-antiplasmin (α2AP), and plasminogen activator inhibitor-1 (PAI-1) are expressed in osteoclasts and osteoblasts and are considered essential in maintaining bone homeostasis by regulating the functions of both osteoclasts and osteoblasts. Additionally, fibrinolytic factors are associated with the regulation of inflammation and the immune system. This review explores the roles of fibrinolytic factors in bone destruction caused by inflammation.

Tissue-plasminogen activator effects on the phenotype of splenic myeloid cells in acute inflammation

Tissue-plasminogen activator (tPA) is a serine protease well known for its fibrinolytic function. Recent studies indicate that tPA could also modulate inflammation via plasmin generation and/or by receptor mediated signalling in vitro. However, the contribution of tPA in inflammatory processes in vivo has not been fully addressed. Therefore, using tPA-deficient mice, we have analysed the effect of lipopolysaccharide (LPS) challenge on the phenotype of myeloid cells including neutrophils, macrophages and dendritic cells (DCs) in spleen. We found that LPS treatment upregulated the frequency of major histocompatibility class two (MHCII+) macrophages but also, paradoxically, induced a deep downregulation of MHCII molecule level on macrophages and on conventional dendritic cells 2 (cDC2). Expression level of the CD11b integrin, known as a tPA receptor, was upregulated by LPS on MHCII+ macrophages and cDC2, suggesting that tPA effects could be amplified during inflammation. In tPA-/- mice under inflammatory conditions, expression of costimulatory CD86 molecules on MHCII+ macrophages was decreased compared to WT mice, while in steady state the expression of MHCII molecules was higher on macrophages. Finally, we reported that tPA deficiency slightly modified the phenotype of DCs and T cells in acute inflammatory conditions. Overall, our findings indicate that in vivo, LPS injection had an unexpectedly bimodal effect on MHCII expression on macrophages and DCs that consequently might affect adaptive immunity. tPA could also participate in the regulation of the T cell response by modulating the levels of CD86 and MHCII molecules on macrophages.

EML4-ALK fusion protein in Lung cancer cells enhances venous thrombogenicity through the pERK1/2-AP-1-tissue factor axis

BACKGROUND

Accumulating evidence links the echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) rearrangement to venous thromboembolism (VTE) in non-small cell lung cancer (NSCLC) patients. However, the corresponding mechanisms remain unclear.

METHOD

High-throughput sequencing analysis of H3122 human ALK-positive NSCLC cells treated with ALK inhibitor/ dimethyl sulfoxide (DMSO) was performed to identify coagulation-associated differential genes between EML4-ALK fusion protein inhibited cells and control cells. Sequentially, we confirmed its expression in NSCLC patients' tissues and in the plasma of a subcutaneous xenograft mouse model. An inferior vena cava (IVC) ligation model was used to assess clot formation potential. Additionally, pathways involved in tissue factor (TF) regulation were explored in ALK-positive cell lines H3122 and H2228. Statistical significance was determined by Student t-test and one-way ANOVA using SPSS.

RESULTS

Sequencing analysis identified a significant downregulation of TF after inhibiting EML4-ALK fusion protein activity in H3122 cells. In clinical NSCLC cases, TF expression was increased especially in ALK-positive NSCLC tissues. Meanwhile, H3122 and H2228 with high TF expression exhibited shorter plasma clotting time and higher TF activity versus ALK-negative H1299 and A549 in cell culture supernatant. Mice bearing H2228 tumor showed a higher concentration of tumor-derived TF and TF activity in plasma and the highest adjusted IVC clot weights. Limiting EML4-ALK protein phosphorylation downregulated extracellular regulated protein kinases 1/2 (ERK1/2)-activating the protein-1(AP-1) signaling pathway and thus attenuated TF expression.

CONCLUSION

EML4-ALK fusion protein may enhance venous thrombogenicity by regulating coagulation factor TF expression. There was potential involvement of the pERK1/2-AP-1 pathway in this process.

Monoclonal enolase-1 blocking antibody ameliorates pulmonary inflammation and fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic fatal disease with limited therapeutic options. The infiltration of monocytes and fibroblasts into the injured lungs is implicated in IPF. Enolase-1 (ENO1) is a cytosolic glycolytic enzyme which could translocate onto the cell surface and act as a plasminogen receptor to facilitate cell migration via plasmin activation. Our proprietary ENO1 antibody, HL217, was screened for its specific binding to ENO1 and significant inhibition of cell migration and plasmin activation (patent: US9382331B2).

METHODS

In this study, effects of HL217 were evaluated in vivo and in vitro for treating lung fibrosis.

RESULTS

Elevated ENO1 expression was found in fibrotic lungs in human and in bleomycin-treated mice. In the mouse model, HL217 reduced bleomycin-induced lung fibrosis, inflammation, body weight loss, lung weight gain, TGF-β upregulation in bronchial alveolar lavage fluid (BALF), and collagen deposition in lung. Moreover, HL217 reduced the migration of peripheral blood mononuclear cells (PBMC) and the recruitment of myeloid cells into the lungs. In vitro, HL217 significantly reduced cell-associated plasmin activation and cytokines secretion from primary human PBMC and endothelial cells. In primary human lung fibroblasts, HL217 also reduced cell migration and collagen secretion.

CONCLUSIONS

These findings suggest multi-faceted roles of cell surface ENO1 and a potential therapeutic approach for pulmonary fibrosis.

The Fibrinolytic System and Its Measurement: History, Current Uses and Future Directions for Diagnosis and Treatment

The fibrinolytic system is a key player in keeping the haemostatic balance, and changes in fibrinolytic capacity can lead to both bleeding-related and thrombosis-related disorders. Our knowledge of the fibrinolytic system has expanded immensely during the last 75 years. From the first successful use of thrombolysis in myocardial infarction in the 1960s, thrombolytic therapy is now widely implemented and has reformed treatment in vascular medicine, especially ischemic stroke, while antifibrinolytic agents are used routinely in the prevention and treatment of major bleeding worldwide. Despite this, this research field still holds unanswered questions. Accurate and timely laboratory diagnosis of disturbed fibrinolysis in the clinical setting remains a challenge. Furthermore, despite growing evidence that hypofibrinolysis plays a central role in, e.g., sepsis-related coagulopathy, coronary artery disease, and venous thromboembolism, there is currently no approved treatment of hypofibrinolysis in these settings. The present review provides an overview of the fibrinolytic system and history of its discovery; measurement methods; clinical relevance of the fibrinolytic system in diagnosis and treatment; and points to future directions for research.

Evaluating the hemostatic effects of tranexamic acid in women with pre-eclampsia

OBJECTIVE

To evaluate the hemostatic effects of tranexamic acid (TXA) ex vivo in women with pre-eclampsia.

METHODS

This was an ex vivo study involving 45 normal pregnant women and 45 women with pre-eclampsia (nine with mild and 36 with severe features) matched for age, gestational age, and body mass index. Blood samples were collected and divided into two parts. The first served as the pre-TXA sample, while the second was spiked with TXA and served as the post-TXA sample. Plasma levels of D-dimer and plasmin-antiplasmin complex (PAP) were determined using enzyme-linked immunosorbent assay.

RESULTS

The mean D-dimer and PAP values in the pre-TXA samples differed significantly between groups. Following spiking with TXA, the mean D-dimer and PAP levels did not differ significantly in the pre-TXA and post-TXA samples (P = 0.560 and P = 0.500, respectively) in the pre-eclampsia cohort. In normal pregnancy, the mean D-dimer and PAP levels in the post-TXA samples did not differ significantly (P = 0.070 and P = 0.050, respectively) from the pre-TXA samples following TXA spiking.

CONCLUSION

TXA did not significantly affect D-dimer and PAP levels in pre-eclampsia, suggesting that TXA may not increase the thrombotic risks in patients with pre-eclampsia.

The effect of sequential perioperative intravenous tranexamic acid in reducing postoperative blood loss and hidden blood loss after posterior lumbar interbody fusion: a randomized controlled trial

Background

Tranexamic acid (TXA) has previously been shown to be effective in reducing intraoperative blood loss (IBL) and transfusion requirements in spine surgery. A conventional TXA regimen is a simple preoperative or intraoperative administration. However, the hyperfibrinolysis caused by surgical trauma lasts at least 24 h, and a single dose of TXA cannot cover the whole process of hyperfibrinolysis. Moreover, its ability to control postoperative blood loss (PBL) may be insufficient. Therefore, this study aimed to explore the effects and safety of sequential perioperative intravenous TXA for reducing bleeding after posterior lumbar interbody fusion (PLIF).

Methods

Patients requiring PLIF were randomly divided into two groups. All patients were intravenously injected with 1 g of TXA 15 min before skin resection. Every day after the surgery, 200 ml saline was intravenously injected for 1-3 days in Group A, while Group B received 1 g of TXA instead of saline. The total blood loss (TBL), IBL, PBL, HCT, Hb, blood transfusion volume, inflammation-related indicators, and complications were recorded.

Results

TBL, PBL, and hidden blood loss (HBL) in Group B were significantly lower than those in Group A (P < 0.05). The maximum decreases in HCT and Hb in Group B were also significantly lower than those in Group A (P < 0.05), and the drainage removal time (DRT) was sooner in Group B than in Group A (P = 0.003). On the 3rd and 5th days after surgery, the level of CRP in Group B was significantly lower than that in Group A (P < 0.05). Similarly, IL-6 levels were significantly lower in Group B for the first 5 days postoperatively (P < 0.001). Sex, operation time, level of decompression, length of incision, and change in HCT were significant predictors of both TBL and HBL. TBL was also significantly associated with BMI and preoperative fibrinogen, while postoperative TXA was a significant predictor of HBL only.

Conclusion

Intravenous injection of 1 g of TXA 15 min before skin resection combined with continuous intravenous injection of 1 g of TXA 1 to 3 days after PLIF can reduce postoperative bleeding and shorten the time to drainage tube removal. In addition, it can also inhibit the postoperative inflammatory response.

Clinical trial registration

ChiCTR2200056210.

Association Between Tranexamic Acid Use and Heterotopic Ossification Prevalence After Elbow Trauma Surgery: A Propensity-Score-Matched Cohort Study

BACKGROUND

Heterotopic ossification (HO) is a common complication of elbow trauma that can affect limb mobility. Inflammation is an initiating factor for HO formation. Tranexamic acid (TXA) can reduce the inflammatory response after orthopaedic surgery. However, evidence regarding the effectiveness of TXA use for HO prevention after elbow trauma surgery is lacking.

METHODS

This retrospective observational propensity-score-matched (PSM) cohort study was conducted from July 1, 2019, to June 30, 2021, at the National Orthopedics Clinical Medical Center, Shanghai, People's Republic of China. A total of 640 patients who underwent surgery following elbow trauma were evaluated. The present study excluded patients with an age of <18 years; those with a history of elbow fracture; those with a central nervous system injury, spinal cord injury, burn injury, or destructive injury; and those who had been lost to follow-up. After 1:1 matching on the basis of sex, age, dominant arm, injury type, open injury, comminuted fracture, ipsilateral trauma, time from injury to surgery, and nonsteroidal anti-inflammatory drug use, the TXA group and the no-TXA group comprised 241 patients each.

RESULTS

In the PSM population, the prevalence of HO was 8.71% in the TXA group and 16.18% in the no-TXA group (with rates of 2.07% and 5.80% for clinically important HO, respectively). Logistic regression analyses showed that TXA use was associated with a lower rate of HO (odds ratio [OR], 0.49; 95% CI, 0.28 to 0.86; p = 0.014) than no TXA use, as well as with a lower rate of clinically important HO (OR, 0.34; 95% CI, 0.11 to 0.91; p = 0.044). None of the baseline covariates significantly affected the relationship between TXA use and HO rate (p > 0.05 for all). Sensitivity analyses supported these findings.

CONCLUSIONS

TXA prophylaxis may be an appropriate method for the prevention of HO following elbow trauma.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

A prognostic gene signature for gastric cancer and the immune infiltration-associated mechanism underlying the signature gene, PLG

BACKGROUND

Globally, gastric cancer (GC) is a common and lethal solid malignant tumor. Identifying the molecular signature and its functions can provide mechanistic insights into GC development and new methods for targeted therapy.

METHODS

Differentially expressed genes (DEGs) and prognostic genes (from univariate Cox regression analysis) were overlapped to obtain prognostic DEGs. Subsequently, molecular modules and the functions of these prognostic DEGs were identified by Metascape and Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG)/Gene Set Enrichment Analysis (GSEA) enrichment analyses, respectively. Protein-protein interaction (PPI) networks of up- and down-regulated prognostic DEGs in GC were analyzed using the MCC algorithm of the Cytohubba plug-in in Cytoscape. The prognostic gene signature was defined on hub genes of the PPI networks by least absolute shrinkage and selection operator (LASSO)-Cox regression analysis. Furthermore, the expressional level of PLG in our clinical GC samples was validated by quantitative PCR (qPCR), western blotting, and immunohistochemistry (IHC). Subsequently, the PLG expression-correlation analysis was performed to assess the role of PLG in GC progression. Immune infiltration analysis was performed by single-sample gene set enrichment analysis (ssGSEA) to assess the inhibitory effect of PLG on immune infiltration.

RESULTS

Firstly, Up- and down-regulated prognostic DEGs and hub genes in protein-protein interaction (PPI) networks in GC were identified. A prognostic five-gene signature (i.e., PLG, SPARC, FGB, SERPINE1, and KLHL41) was identified. Among the five genes, the relationship between plasminogen (PLG) and GC remains largely unclear. Moreover, the functions of PLG-correlated genes in GC, like 'fibrinolysis', 'hemostasis', 'ion channel complex', and 'transporter complex' were identified. In addition, PLG expression correlated negatively with the infiltration of almost all immune cell types. Interestingly, the expression of PLG was significantly and highly correlated with that of CD160, an immune checkpoint inhibitor.

CONCLUSION

Our findings defined a new five-gene signature for predicting GC prognosis, but more validation is required to assess the effects and mechanism of the five genes, especially PLG, for the development of new GC therapies.

Mechanism of Action of Topical Tranexamic Acid in the Treatment of Melasma and Sun-Induced Skin Hyperpigmentation

Tranexamic acid (TXA) has anti-plasmin activity and has been shown when administered orally to be effective against melasma, for which it is considered first-line pharmacotherapy. Several studies have shown that topically applied TXA is also effective against melasma and skin hyperpigmentation caused by sunburn and inflammation. The TXA concentration in the epidermis and dermis/vasculature has been estimated from its distribution in the skin after closed application, and topically applied TXA has thus been shown to act on neutrophils and mast cells in the dermis and on the vascular system. It is unlikely that topically applied TXA acts on dermal neutrophils or mast cells or on the vascular system to form thrombi. As discussed in the present review, studies on the effects of topical TXA on the hyperpigmentation process indicate that the resulting skin-lightening mechanism involves the suppression of cytokine/chemical mediator production, which stimulates melanin production via the keratinocyte-derived urokinase-type plasminogen activator and plasminogen derived from dermal vascular in the basal layer of the epidermis, thereby suppressing the production of excessive melanin to prevent hyperpigmentation.

Coagulation and complement: Key innate defense participants in a seamless web

In 1969, Dr. Oscar Ratnoff, a pioneer in delineating the mechanisms by which coagulation is activated and complement is regulated, wrote, “In the study of biological processes, the accumulation of information is often accelerated by a narrow point of view. The fastest way to investigate the body’s defenses against injury is to look individually at such isolated questions as how the blood clots or how complement works. We must constantly remind ourselves that such distinctions are man-made. In life, as in the legal cliché, the devices through which the body protects itself form a seamless web, unwrinkled by our artificialities.” Our aim in this review, is to highlight the critical molecular and cellular interactions between coagulation and complement, and how these two major component proteolytic pathways contribute to the seamless web of innate mechanisms that the body uses to protect itself from injury, invading pathogens and foreign surfaces.

Tranexamic acid: Beyond antifibrinolysis

Tranexamic acid (TXA) is a popular antifibrinolytic drug widely used in hemorrhagic trauma patients and cardiovascular, orthopedic, and gynecological surgical patients. TXA binds plasminogen and prevents its maturation to the fibrinolytic enzyme plasmin. A number of studies have demonstrated the broad life-saving effects of TXA in trauma, superior to those of other antifibrinolytic agents. Besides preventing fibrinolysis and blood loss, TXA has been reported to suppress posttraumatic inflammation and edema. Although the efficiency of TXA transcends simple inhibition of fibrinolysis, little is known about its mechanisms of action besides the suppression of plasmin maturation. Understanding the broader effects of TXA at the cell, organ, and organism levels are required to elucidate its potential mechanisms of action transcending antifibrinolytic activity. In this article, we provide a brief review of the current clinical use of TXA and then focus on the effects of TXA beyond antifibrinolytics such as its anti-inflammatory activity, protection of the endothelial and epithelial monolayers, stimulation of mitochondrial respiration, and suppression of melanogenesis.

Tranexamic Acid and Its Potential Anti-Inflammatory Effect: A Systematic Review

Tranexamic acid (TXA) is an antifibrinolytic drug primarily used for reducing blood loss in patients with major bleedings. Animal and cell studies have shown that TXA might modulate the inflammatory response by either enhancing or inhibiting cytokine levels. Furthermore, recent human studies have found altered inflammatory biomarkers in patients receiving TXA when compared with patients who did not receive TXA. In this systematic review we investigated the effect of TXA on inflammatory biomarkers in different patient groups. A systematic literature search was conducted on the databases PubMed and Embase to identify all original articles that investigated inflammatory biomarkers in patients receiving TXA and compared them to a relevant control group. The review was performed according to the PRISMA guidelines, and the literature search was performed on November 29, 2021. Thirty-three studies were included, among which 14 studies compared patients receiving TXA with patients getting no medication, another 14 studies investigated different dosing regimens of TXA, and finally five studies examined the administration form of TXA. The present review suggests that TXA has an anti-inflammatory effect in patients undergoing orthopaedic surgery illustrated by decreased levels of C-reactive protein and interleukin-6 in patients receiving TXA compared with patients receiving no or lower doses of TXA. However, the anti-inflammatory effect was not found in patients undergoing cardiac surgery, pediatric craniosynostosis patients, or in rheumatoid arthritis patients. The inflammatory response was not affected by administration form of TXA (oral, intravenous, or topical). In conclusion, an anti-inflammatory effect of TXA was consistently found among orthopaedic patients only.

Histone 2B Facilitates Plasminogen-Enhanced Endothelial Migration through Protease-Activated Receptor 1 (PAR1) and Protease-Activated Receptor 2 (PAR2)

Plasminogen and its multiple receptors have been implicated in the responses of many different cell types. Among these receptors, histone 2B (H2B) has been shown to play a prominent role in macrophage responses. The contribution of H2B to plasminogen-induced endothelial migration, an event relevant to wound healing and angiogenesis, is unknown. Plasminogen enhanced the migration of endothelial cells, which was inhibited by both Protease-Activated Receptor-1 (PAR1) and 2 (PAR2) antagonists. H2B was detected on viable endothelial cells of venous and arterial origin, and an antibody to H2B that blocks plasminogen binding also inhibited the plasminogen-dependent migration by these cells. The antibody blockade was as effective as PAR1 or PAR2 antagonists in inhibiting endothelial cell migration. In pull-down experiments, H2B formed a complex with both PAR1 and PAR2 but not β3 integrin, another receptor implicated in endothelial migration in the presence of plasminogen. H2B was found to be associated with clathrin adapator protein, AP2µ (clathrin AP2µ) and β-arrestin2, which are central to the internationalization/signaling machinery of the PARs. These associations with PAR1-clathrin adaptor AP2µ- and PAR2-β-arrestin2-dependent internalization/signaling pathways provide a mechanism to link plasminogen to responses such as wound healing and angiogenesis.

Roles of the tissue-type plasminogen activator in immune response

The COVID-19 pandemic has once again brought to the forefront the existence of a tight link between the coagulation/fibrinolytic system and the immunologic processes. Tissue-type plasminogen activator (tPA) is a serine protease with a key role in fibrinolysis by converting plasminogen into plasmin that can finally degrade fibrin clots. tPA is released in the blood by endothelial cells and hepatocytes but is also produced by various types of immune cells including T cells and monocytes. Beyond its role on hemostasis, tPA is also a potent modulator of inflammation and is involved in the regulation of several inflammatory diseases. Here, after a brief description of tPA structure, we review its new functions in adaptive immunity focusing on T cells and antigen presenting cells. We intend to synthesize the recent knowledge on proteolysis- and receptor-mediated effects of tPA on immune response in physiological and pathological context.

Cerebral Amyloid Angiopathy and the Fibrinolytic System: Is Plasmin a Therapeutic Target?

Cerebral amyloid angiopathy is a devastating cause of intracerebral hemorrhage for which there is no specific secondary stroke prevention treatment. Here we review the current literature regarding cerebral amyloid angiopathy pathophysiology and treatment, as well as what is known of the fibrinolytic pathway and its interaction with amyloid. We postulate that tranexamic acid is a potential secondary stroke prevention treatment agent in sporadic cerebral amyloid angiopathy, although further research is required.

Enzymatically Inactive Tissue-Type Plasminogen Activator Reverses Disease Progression in the Dextran Sulfate Sodium Mouse Model of Inflammatory Bowel Disease

Enzymatically inactive tissue-type plasminogen activator (EI-tPA) does not activate fibrinolysis, but interacts with the N-methyl-d-aspartate receptor (NMDA-R) and low-density lipoprotein receptor-related protein-1 (LRP1) in macrophages to block innate immune system responses mediated by toll-like receptors. Herein, we examined the ability of EI-tPA to treat colitis in mice, induced by dextran sulfate sodium. In two separate studies, designed to generate colitis of differing severity, a single dose of EI-tPA administered after inflammation established significantly improved disease parameters. EI-tPA-treated mice demonstrated improved weight gain. Stools improved in character and became hemoccult negative. Abdominal tenderness decreased. Colon shortening significantly decreased in EI-tPA-treated mice, suggesting attenuation of irreversible tissue damage and remodeling. Furthermore, histopathologic evidence of disease decreased in the distal 25% of the colon in EI-tPA-treated mice. EI-tPA did not decrease the number of CD45-positive leukocytes or F4/80-positive macrophage-like cells detected in extracts of colons from dextran sulfate sodium-treated mice as assessed by flow cytometry. However, multiple colon cell types expressed the NMDA-R, suggesting the ability of diverse cells, including CD3-positive cells, CD103-positive cells, Ly6G-positive cells, and epithelial cell adhesion molecule-positive epithelial cells to respond to EI-tPA. Mesenchymal cells that line intestinal crypts and provide barrier function expressed LRP1, thereby representing another potential target for EI-tPA. These results demonstrate that the NMDA-R/LRP1 receptor system may be a target for drug development in diseases characterized by tissue damage and chronic inflammation.

Fibrinolysis: A Primordial System Linked to the Immune Response

The fibrinolytic system provides an essential means to remove fibrin deposits and blood clots. The actual protease responsible for this is plasmin, formed from its precursor, plasminogen. Fibrin is heralded as it most renowned substrate but for many years plasmin has been known to cleave many other substrates, and to also activate other proteolytic systems. Recent clinical studies have shown that the promotion of plasmin can lead to an immunosuppressed phenotype, in part via its ability to modulate cytokine expression. Almost all immune cells harbor at least one of a dozen plasminogen receptors that allows plasmin formation on the cell surface that in turn modulates immune cell behavior. Similarly, a multitude of pathogens can also express their own plasminogen activators, or contain surface proteins that provide binding sites host plasminogen. Plasmin formed under these circumstances also empowers these pathogens to modulate host immune defense mechanisms. Phylogenetic studies have revealed that the plasminogen activating system predates the appearance of fibrin, indicating that plasmin did not evolve as a fibrinolytic protease but perhaps has its roots as an immune modifying protease. While its fibrin removing capacity became apparent in lower vertebrates these primitive under-appreciated immune modifying functions still remain and are now becoming more recognised.

Exploration of Active Site-Directed Plasmin Inhibitors: Beyond Tranexamic Acid

Plasmin (Plm), a trypsin-like serine protease, is responsible for fibrinolysis pathway and pathologic events, such as angiogenesis, tumor invasion, and metastasis, and alters the expression of cytokines. A growing body of data indicates that a Plm inhibitor is a potential candidate as an anti-inflammatory and anti-cancer agent. A class of active site-directed plasmin inhibitors containing tranexamic acid residue has been designed. As evidenced by docking studies, the inhibitor binds to the active site not to the lysine binding site (LBS) in plasmin, thus preventing plasmin from digesting the substrate. Further optimization of the series, concerning both activity and selectivity, led to the second generation of inhibitors. This review focuses on the Plm inhibitory activity-structure relationship of Plm inhibitors with the goal of realizing their design and clinical application.

Plasminogen Receptors and Fibrinolysis

The ability of cells to promote plasminogen activation on their surfaces is now well recognized, and several distinct cell surface proteins have been demonstrated to function as plasminogen receptors. Here, we review studies demonstrating that plasminogen bound to cells, in addition to plasminogen directly bound to fibrin, plays a major role in regulating fibrin surveillance. We focus on the ability of specific plasminogen receptors on eukaryotic cells to promote fibrinolysis in the in vivo setting by reviewing data obtained predominantly in murine models. Roles for distinct plasminogen receptors in fibrin surveillance in intravascular fibrinolysis, immune cell recruitment in the inflammatory response, wound healing, and lactational development are discussed.

The effect of multiple-dose oral versus intravenous tranexamic acid in reducing postoperative blood loss and transfusion rate after adolescent scoliosis surgery: a randomized controlled trial

BACKGROUND CONTEXT

Tranexamic acid (TXA) is widely used in surgery for adolescent idiopathic scoliosis (AIS) and has been proved to be efficacious in reducing intraoperative blood loss (IBL) and the transfusion rate. However, the routine TXA regimen was intraoperative administration alone, in which the concentration of TXA could not cover the whole process of hyperfibrinolysis. And, its ability to control the massive postoperative blood loss (PBL) may be insufficient. Thus, we promoted a multiple-dose regimen of TXA for patients with AIS who underwent surgical correction.

PURPOSE

The primary aims were (1) to determine whether the multiple-dose regimen of TXA could reduce PBL and the postoperative transfusion rate, and (2) to compare the efficacy of oral administration with intravenous administration. The secondary aims were (3) to evaluate whether this regimen could alleviate inflammatory response, and (4) to assess the occurrence of drug-related side effects.

STUDY DESIGN

Prospective, double-blinded, randomized controlled trial.

PATIENT SAMPLE

A total of 108 patients with AIS who underwent posterior scoliosis correction and spinal fusion (PSS) were enrolled in this study.

OUTCOME MEASURES

The primary parameters were PBL and postoperative transfusion rate. Other parameters such as total blood loss (TBL), maximum hemoglobin (Hb) decrease, volume of drainage, inflammation markers (interleukin-6 [IL-6] and C-reactive protein [CRP]), and occurrence of complications were also collected and compared. Multiple regression analysis was used to examine the variables that affected PBL.

METHODS

Patients were randomized into three groups. All patients received intravenous TXA 50 mg/kg loading dose and 10 mg/kg/h maintenance dose during surgery. Group A received 1 g oral TXA at 4 hours, 10 hours, and 16 hours postoperatively; group B received 0.5 g intravenous TXA at 6 hours, 12 hours, and 18 hours postoperatively; group C received placebo.

RESULTS

The mean PBL and postoperative transfusion rate in group A (957.8±378.9 mL, 13.89%) and B (980.3±491.8 mL, 11.11%) were significantly lower than those in group C [1,495.9±449.6 mL, mean differences=538.1 mL, 95% confidence interval (CI), 290.1-786.1 mL, p<0.001; 515.6 mL, 95% CI, 267.6-763.6 mL, p<.001]; (36.11%, p=.029, p=.013). Meanwhile, the mean TBL, maximum Hb decrease, and volume of drainage were also significantly lower in group A and B than in group C. IL-6 and CRP in group A and B were significantly lower than in group C from postoperative days 1 to 3. All these differences were not significant between groups A and B. No drug-related complications were observed in any patient. Multiple regression showed that the application of postoperative TXA and number of screws were significant parameters affecting PBL.

CONCLUSIONS

A multiple-dose regimen of TXA, either by oral or intravenous application, could be a safe and effective means of controlling PBL and decreasing the postoperative transfusion rate in patients with AIS who underwent scoliosis surgery. In addition, it could inhibit postoperative inflammatory response.

The plasminogen receptor, Plg-RKT, plays a role in inflammation and fibrinolysis during cutaneous wound healing in mice

Wound healing is a complex physiologic process that proceeds in overlapping, sequential steps. Plasminogen promotes fibrinolysis and potentiates the inflammatory response during wound healing. We have tested the hypothesis that the novel plasminogen receptor, Plg-R_KT, regulates key steps in wound healing. Standardized burn wounds were induced in mice and time dependence of wound closure was quantified. Healing in Plg-R_KT^−/− mice was significantly delayed during the proliferation phase. Expression of inflammatory cytokines was dysregulated in Plg-R_KT^−/− wound tissue. Consistent with dysregulated cytokine expression, a significant delay in wound healing during the proliferation phase was observed in mice in which Plg-R_KT was specifically deleted in myeloid cells. Following wound closure, the epidermal thickness was less in Plg-R_KT^−/− wound tissue. Paradoxically, deletion of Plg-R_KT, specifically in keratinocytes, significantly accelerated the rate of healing during the proliferation phase. Mechanistically, only two genes were upregulated in Plg-R_KT^−/− compared with Plg-R_KT^+/+ wound tissue, filaggrin, and caspase 14. Both filaggrin and caspase 14 promote epidermal differentiation and decrease proliferation, consistent with more rapid wound closure and decreased epidermal thickness during the remodeling phase. Fibrin clearance was significantly impaired in Plg-R_KT^−/− wound tissue. Genetic reduction of fibrinogen levels to 50% completely abrogated the effect of Plg-R_KT deletion on the healing of burn wounds. Remarkably, the effects of Plg-R_KT deletion on cytokine expression were modulated by reducing fibrinogen levels. In summary, Plg-R_KT is a new regulator participating in different phases of cutaneous burn wound healing, which coordinately plays a role in the interrelated responses of inflammation, keratinocyte migration, and fibrinolysis.

Functions of the plasminogen receptor Plg-RKT

Plg-RKT is a structurally unique transmembrane plasminogen receptor with both N- and C-terminal domains exposed on the extracellular face of the cell. Its C-terminal lysine functions to tether plasminogen to cell surfaces. Overexpression of Plg-RKT increases cell surface plasminogen binding capacity while genetic deletion of Plg-RKT decreases plasminogen binding. Plasminogen binding to Plg-RKT results in promotion of plasminogen activation to the broad spectrum serine protease plasmin. This function is promoted by the physical association of Plg-RKT with the urokinase receptor (uPAR). Plg-RKT is broadly expressed in cells and tissues throughout the organism and its sequence is remarkably conserved phylogenetically. Plg-RKT also is required for lactation and, thus, is necessary for survival of the species. This review provides an overview of established and emerging functions of Plg-RKT and highlights major roles for Plg-RKT in both the initiation and resolution of inflammation. While the roles for Plg-RKT in the inflammatory response are predominantly plasmin(ogen)-dependent, its role in lactation requires both plasminogen-dependent and plasminogen-independent mechanisms. Furthermore, the functions of Plg-RKT are dependent on sex. In view of the broad tissue distribution of Plg-RKT , its role in a broad array of physiological and pathological processes should provide a fruitful area for future investigation.

The Immunologic Effect of Early Intravenous Two and Four Gram Bolus Dosing of Tranexamic Acid Compared to Placebo in Patients With Severe Traumatic Bleeding (TAMPITI): A Randomized, Double-Blind, Placebo-Controlled, Single-Center Trial

Background

The hemostatic properties of tranexamic acid (TXA) are well described, but the immunological effects of TXA administration after traumatic injury have not been thoroughly examined. We hypothesized TXA would reduce monocyte activation in bleeding trauma patients with severe injury.

Methods

This was a single center, double-blinded, randomized controlled trial (RCT) comparing placebo to a 2 g or 4 g intravenous TXA bolus dose in trauma patients with severe injury. Fifty patients were randomized into each study group. The primary outcome was a reduction in monocyte activation as measured by human leukocyte antigen-DR isotype (HLA-DR) expression on monocytes 72 h after TXA administration. Secondary outcomes included kinetic assessment of immune and hemostatic phenotypes within the 72 h window post-TXA administration.

Results

The trial occurred between March 2016 and September 2017, when data collection ended. 149 patients were analyzed (placebo, n = 50; 2 g TXA, n = 49; 4 g TXA, n = 50). The fold change in HLA-DR expression on monocytes [reported as median (Q1–Q3)] from pre-TXA to 72 h post-TXA was similar between placebo [0.61 (0.51–0.82)], 2 g TXA [0.57 (0.47–0.75)], and 4 g TXA [0.57 (0.44–0.89)] study groups (p = 0.82). Neutrophil CD62L expression was reduced in the 4 g TXA group [fold change: 0.73 (0.63–0.97)] compared to the placebo group [0.97 (0.78–1.10)] at 24 h post-TXA (p = 0.034). The fold decrease in plasma IL-6 was significantly less in the 4 g TXA group [1.36 (0.87–2.42)] compared to the placebo group [0.46 (0.19–1.69)] at 72 h post-TXA (p = 0.028). There were no differences in frequencies of myeloid or lymphoid populations or in classical complement activation at any of the study time points.

Conclusion

In trauma patients with severe injury, 4 g intravenous bolus dosing of TXA has minimal immunomodulatory effects with respect to leukocyte phenotypes and circulating cytokine levels.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT02535949.

Tranexamic acid modulates the immune response and reduces postsurgical infection rates

Tranexamic acid (TXA) is an antifibrinolytic agent that blocks plasmin formation. Because plasmin is known to promote inflammatory and immunosuppressive responses, we explored the possibility that plasmin-mediated immunosuppression in patients undergoing cardiac surgery can be directly reversed by TXA and decrease postoperative infection rates. The modulatory effect of TXA on inflammatory cytokine levels and on innate immune cell activation were evaluated with multiplex enzyme-linked immunosorbent assay and flow cytometry, respectively. Postoperative infection rates were determined in patients undergoing cardiac surgery and randomized to TXA (ACTRN12605000557639; http://www.anzca.edu.au). We demonstrate that TXA-mediated plasmin blockade modulates the immune system and reduces surgery-induced immunosuppression in patients following cardiac surgery. TXA enhanced the expression of immune-activating markers while reducing the expression of immunosuppressive markers on multiple myeloid and lymphoid cell populations in peripheral blood. TXA administration significantly reduced postoperative infection rates, despite the fact that patients were being administered prophylactic antibiotics. This effect was independent of the effect of TXA at reducing blood loss. TXA was also shown to exert an immune-modulatory effect in healthy volunteers, further supporting the fibrin-independent effect of TXA on immune function and indicating that baseline plasmin levels contribute to the regulation of the immune system in the absence of any comorbidity or surgical trauma. Finally, the capacity of TXA to reduce infection rates, modulate the innate immune cell profile, and generate an antifibrinolytic effect overall was markedly reduced in patients with diabetes, demonstrating for the first time that the diabetic condition renders patients partially refractory to TXA.

Tranexamic acid attenuates inflammatory effect and modulates immune response in primary total knee arthroplasty: a randomized, placebo-controlled, pilot trial

AIMS

To explore the effect of intravenous tranexamic acid (IV-TXA) on inflammation and immune response following primary total knee arthroplasty (TKA).

METHODS

Primary TKA patients (n = 125) were randomized into the following four groups: group A to receive placebo; group B to receive a single dose of 20 mg kg^-1 IV-TXA and 20 mg of intravenous dexamethasone (IV-DXM); group C to receive six doses of IV-TXA (total dosage > 6 g); and group D to receive six doses of IV-TXA combined with three doses of IV-DXM (total dosage = 40 mg). The primary outcomes were C-reactive protein (CRP) and interleukin (IL)-6 levels and the secondary outcomes were complement C3 and C4 and T-cell subset levels, which were measured preoperatively and at 24 h, 48 h, 72 h, and 2 weeks postoperatively.

RESULTS

The postoperative peak CRP and IL-6 levels in group C (93.7 ± 22.2 mg L^-1, 108.8 ± 41.7 pg mL^-1) were lower compared with those in group A (134.7 ± 28.8 mg L^-1, P < 0.01; 161.6 ± 64.4 pg mL^-1, P < 0.01). Groups B and D exhibited significantly lower CRP and IL-6 levels compared with groups A and C at 24 h, 48 h, and 72 h postoperatively (P < 0.05 for all). In group C, complement C3 and C4 levels were higher compared with those in group A at 48 h (0.967 ± 0.127 g L^-1 vs. 0.792 ± 0.100 g L^-1, P < 0.01; 0.221 ± 0.046 g L^-1 vs. 0.167 ± 0.028 g L^-1, P < 0.01) and 72 h (1.050 ± 0.181 g L^-1 vs. 0.860 ± 0.126 g L^-1, P = 0.01; 0.240 ± 0.052 g L^-1 vs. 0.182 ± 0.036 g L^-1, P < 0.01) postoperatively and CD3 and CD4 subset levels were higher compared with those in group B at 24 h postoperatively (66.78 ± 9.29% vs. 56.10 ± 12.47%, P < 0.05; 36.69 ± 5.78% vs. 28.39 ± 8.89%, P < 0.05).

CONCLUSION

Six doses of IV-TXA could attenuate the inflammatory effect, modulate the immune response, and reduce immunosuppression caused by DXM in patients after TKA.

A comparative study on root and bark extracts of Eleutherococcus senticosus and their effects on human macrophages

BACKGROUND

Eleutherococcus senticosus or Siberian ginseng is a medicinal plant containing adaptogenic substances believed to regulate immune responses. Both, the root and stem bark are commonly used in traditional medicines.

PURPOSE

The purpose of the present study is to chemically characterize E. senticosus root and bark extracts and to compare their effects on functions of human primary macrophages.

STUDY DESIGN AND METHODS

HPLC-DAD-MS analysis was used to characterize chemical constituents of alcoholic extracts from E. senticosus root and bark. The data obtained and available databases were combined for network pharmacology analysis. Involvement of predicted pathways was further functionally confirmed by using monocyte-derived human macrophages and endotoxin-free E. senticosus root and bark extracts.

RESULTS

Chemical analysis showed that the root extract contained more syringin, caffeic acid, and isofraxidin than the bark extract. At variance, bark extract contained more sesamin and oleanolic acid. Coniferyl aldehyde and afzelin were below the limit of quantification in both extracts. Network pharmacology analysis indicated that constituents of E. senticosus might affect the immune cell phenotype and signaling pathways involved in cell metabolism and cytoskeleton regulation. Indeed, both extracts promoted actin polymerization, migration, and phagocytosis of E. coli by macrophages pointing to macrophage polarization towards the M2 phenotype. In addition, treatment with E. senticosus root and bark extracts decreased phosphorylation of Akt on Ser473 and significantly reduced expression of the hemoglobin scavenger receptor CD163 by macrophages. Neither extract affected expression of CD11b, CD80, or CD64 by macrophages. In addition, macrophages treated with the bark extract, but not with the root extract, exhibited activated p38 MAPK and NF-κB and released increased, but still moderate, amounts of proinflammatory TNF-α and IL-6, anti-inflammatory IL-10, and chemotactic CCL1, which all together point to a M2b-like macrophage polarization. Differently, the root extract increased the IL-4-induced expression of anti-inflammatory CD200R. These changes in monocytes are in agreement with an increased M2a macrophage polarization.

CONCLUSION

The ability of E. senticosus root and bark extracts to promote polarization of human macrophages towards anti-inflammatory M2a and M2b phenotypes, respectively, might underlay the immunoregulatory activities and point to potential wound healing promoting effects of this medicinal plant.

Using antifibrinolytics to tackle neuroinflammation

Plasmin is generally known as a promotor of inflammation. Recent advancement suggests that it has a complex role as immunity modulator. Pharmacological inhibition of plasmin production and activity has been proven to improve neurological outcomes in traumatic brain injury and subarachnoid hemorrhage, most probably by preventing re-bleeding. The immune-modulatory properties of antifibrinolytics, however, suggest that they probably have effects unrelated to fibrinolysis inhibition, which are currently not adequately harnessed. The present work aims to give an account of the existing data regarding antifibrinolytics as agents influencing neuroinflammation. Preclinical and clinical studies on the possible influence of antifibrinolytics on neuroinflammation are scarce. However, the emerging evidence suggests that inhibition of plasmin(ogen) activity can ameliorate neuroinflammation to some extent. This data demonstrate that plasmin(ogen) is not exclusively involved in fibrinolysis, but also has other substrates and can precipitate in inflammatory processes. Investigation on the role of plasmin as the factor for the development of neuroinflammation shows the significant potential of antifibrinolytics as pharmacotherapy of neuroinflammationm, which is worthy of further exploration.

Is there a correlation between inflammatory markers and coagulation parameters in women with advanced ovarian endometriosis?

Background

Endometriosis is defined as a chronic inflammatory disease. Recent studies have shown that increased coagulation parameters including fibrinogen and platelets are associated with endometriosis. The objective of this study was to determine the levels of inflammatory markers and coagulation parameters and their correlations in women with endometriomas compared to those with benign ovarian cysts or normal pelvic anatomy.

Methods

Between June 2015 and June 2017, a total of 548 women who underwent laparoscopic/laparotomic surgery for ovarian endometriomas (OMA group, n = 226), non-endometriosis benign ovarian cysts (Cyst group, n = 210) and tubal reanastomosis (Control group, n = 112) were recruited in this study. Inflammatory markers including c-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and coagulation parameters including platelet count, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time, and plasma fibrinogen as well as CA-125 were determined.

Results

Compared with Cyst group and Control group, TT and PT in OMA group were significantly shorter and plasma fibrinogen levels were significantly higher (P < 0.05). Moreover, the levels of plasma fibrinogen were positively correlated with CRP, NLR and PLR (P < 0.05). In addition, the confidence intervals for the area under the curve (AUC) for CA-125 × fibrinogen were significantly higher than those for CA-125 (0.904–0.952 vs. 0.899–0.949) in the diagnosis of endometrioma.

Conclusions

These results indicate that women with endometriomas demonstrate a hypercoagulable status due to the inflammatory nature of endometriosis. The combined determination for CA-125 and fibrinogen demonstrate a higher area under the curve than the single detection of CA-125 in those with endometriomas compared to these with benign ovarian cysts.

Trial registration

This study was approved by the Human Ethics Committee of the Women’s Hospital, School of Medicine, Zhejiang University (No.20170174) and all women provided written informed consent.

Dichotomous Role of Plasmin in Regulation of Macrophage Function after Acetaminophen Overdose

Kupffer cells and monocyte-derived macrophages are critical for liver repair after acetaminophen (APAP) overdose. These cells produce promitogenic cytokines and growth factors, and they phagocytose dead cell debris, a process that is critical for resolution of inflammation. The factors that regulate these dynamic functions of macrophages after APAP overdose, however, are not fully understood. We tested the hypothesis that the fibrinolytic enzyme, plasmin, is a key regulator of macrophage function after APAP-induced liver injury. In these studies, inhibition of plasmin in mice with tranexamic acid delayed up-regulation of proinflammatory cytokines after APAP overdose. In culture, plasmin directly, and in synergy with high-mobility group B1, stimulated Kupffer cells and bone marrow-derived macrophages to produce cytokines by a mechanism that required NF-κB. Inhibition of plasmin in vivo also prevented trafficking of monocyte-derived macrophages into necrotic lesions after APAP overdose. This prevented phagocytic removal of dead cells, prevented maturation of monocyte-derived macrophages into F4/80-expressing macrophages, and prevented termination of proinflammatory cytokine production. Our studies reveal further that phagocytosis is an important stimulus for cessation of proinflammatory cytokine production as treatment of proinflammatory, monocyte-derived macrophages, isolated from APAP-treated mice, with necrotic hepatocytes decreased expression of proinflammatory cytokines. Collectively, these studies demonstrate that plasmin is an important regulator of macrophage function after APAP overdose.

Tissue-type plasminogen activator neutralizes LPS but not protease-activated receptor-mediated inflammatory responses to plasmin

Tissue-type plasminogen activator (tPA) activates fibrinolysis and also suppresses innate immune system responses to LPS in bone marrow-derived macrophages (BMDMs) and in vivo in mice. The objective of this study was to assess the activity of tPA as a regulator of macrophage physiology in the presence of plasmin. Enzymatically active and enzymatically inactive (EI) tPA appeared to comprehensively block the response to LPS in BMDMs, including expression of proinflammatory cytokines such as TNF-α and IL-1β and anti-inflammatory cytokines such as IL-10 and IL-1 receptor antagonist. The activity of EI-tPA as an LPS response modifier was conserved in the presence of plasminogen. By contrast, in BMDMs treated with tPA and plasminogen or preactivated plasmin, in the presence or absence of LPS, increased proinflammatory cytokine expression was observed and tPA failed to reverse the response. Plasmin independently activated NF-κB, ERK1/2, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase in BMDMs, which is characteristic of proinflammatory stimuli. Plasmin-induced cytokine expression was blocked by ε-aminocaproic acid, aprotinin, and inhibitors of the known plasmin substrate, Protease-activated receptor-1 (PAR-1), but not by N-methyl-d-aspartate receptor inhibitor, which blocks the effects of tPA on macrophages. Cytokine expression by BMDMs treated with the PAR-1 agonist, TFLLR, was not inhibited by EI-tPA, possibly explaining why EI-tPA does not inhibit macrophage responses to plasmin and providing evidence for specificity in the ability of tPA to oppose proinflammatory stimuli. Regulation of innate immunity by the fibrinolysis system may reflect the nature of the stimulus and a balance between the potentially opposing activities of tPA and plasmin.

Antifibrinolytic Therapy and Perioperative Considerations

Fibrinolysis is a physiologic component of hemostasis that functions to limit clot formation. However, after trauma or surgery, excessive fibrinolysis may contribute to coagulopathy, bleeding, and inflammatory responses. Antifibrinolytic agents are increasingly used to reduce bleeding, allogeneic blood administration, and adverse clinical outcomes. Tranexamic acid is the agent most extensively studied and used in most countries. This review will explore the role of fibrinolysis as a pathologic mechanism, review the different pharmacologic agents used to inhibit fibrinolysis, and focus on the role of tranexamic acid as a therapeutic agent to reduce bleeding in patients after surgery and trauma.

Identification of key genes associated with rheumatoid arthritis with bioinformatics approach

We aimed to identify key genes associated with rheumatoid arthritis (RA).The microarray datasets of GSE1919, GSE12021, and GSE21959 (35 RA samples and 32 normal controls) were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) in RA samples were identified using the t test in limma package. Functional enrichment analysis was performed using clusterProfiler package. A protein-protein interaction (PPI) network of selected DEGs was constructed based on the Human Protein Reference Database. Active modules were explored using the jActiveModules plug-in in the Cytoscape Network Modeling package.In total, 537 DEGs in RA samples were identified, including 241 upregulated and 296 downregulated genes. A total of 24,451 PPI pairs were collected, and 5 active modules were screened. Furthermore, 19 submodules were acquired from the 5 active modules. Discs large homolog 1 (DLG1) and related DEGs such as guanylate cyclase 1, soluble, alpha 2 (GUCY1A2), N-methyl d-aspartate receptor 2A subunit (GRIN2A), and potassium voltage-gated channel member 1 (KCNA1) were identified in 8 submodules. Plasminogen (PLG) and related DEGs such as chemokine (C-X-C motif) ligand 2 (CXCL2), laminin, alpha 3 (LAMA3), complement component 7 (C7), and coagulation factor X (F10) were identified in 4 submodules.Our results indicate that DLG1, GUCY1A2, GRIN2A, KCNA1, PLG, CXCL2, LAMA3, C7, and F10 may play key roles in the progression of RA and may serve as putative therapeutic targets for treating RA.

Acetyl-lupeolic acid inhibits Akt signaling and induces apoptosis in chemoresistant prostate cancer cells in vitro and in vivo

The triterpenoid acetyl-lupeolic acid (ac-LA) isolated from the oleogum resin of Boswellia carterii reduced the viability of a panel of cancer cell lines more efficiently than lupeol. There was no detectable intracellular conversion of ac-LA to lupeol and vice versa. In contrast to docetaxel, ac-LA did not induce selection of treatment-resistant cancer cells. By various parameters including DNA fragmentation, ac-LA was shown to induce apoptosis in androgen-independent PC-3 cells, whereas in MDA-MB-231 breast cancer cells, ac-LA led to cell accumulation in the G₂/M phase of the cell cycle, but not to apoptosis. In silico docking combined with in vitro kinase assays implied that ac LA potently inhibits Akt mainly by direct binding to the pleckstrin homology domain. Consistently, an Akt1 mutant deficient of the PH domain afforded partial resistance to ac-LA and complete resistance to lupeol and the Akt inhibitor III. Ac-LA inhibited phosphorylation of downstream targets of the Akt signaling pathway, which was followed by inhibition of the mTOR target p70 ribosomal six protein kinase and the nuclear accumulation of p65/NF-κB, β-catenin, and c-myc, as well as loss of the mitochondrial membrane potential. Ac-LA exhibited antiproliferative, proapoptotic, and antitumorigenic effects on PC-3-tumors xenografted either on chick chorioallantoic membranes or in nude mice. Ac-LA exhibited a clearly better safety profile than docetaxel or lupeol during chronic administration in vivo. In contrast to lupeol, ac-LA also inhibited release of vascular endothelial growth factor in vitro and accordingly angiogenesis in vivo. Thus, ac-LA deserves further exploration as a potential new antitumor compound.

Chemically different non-thermal plasmas target distinct cell death pathways

A rigorous biochemical analysis of interactions between non-thermal plasmas (NTPs) and living cells has become an important research topic, due to recent developments in biomedical applications of non-thermal plasmas. Here, we decouple distinct cell death pathways targeted by chemically different NTPs. We show that helium NTP cells treatment, results in necrosome formation and necroptosis execution, whereas air NTP leads to mTOR activation and autophagy inhibition, that induces mTOR-related necrosis. On the contrary, ozone (abundant component of air NTP) treatment alone, exhibited the highest levels of reactive oxygen species production leading to CypD-related necrosis via the mitochondrial permeability transition. Our findings offer a novel insight into plasma-induced cellular responses, and reveal distinct cell death pathways triggered by NTPs.

Pharmacological targeting of plasmin prevents lethality in a murine model of macrophage activation syndrome

Macrophage activation syndrome (MAS) is a life-threatening disorder characterized by a cytokine storm and multiorgan dysfunction due to excessive immune activation. Although abnormalities of coagulation and fibrinolysis are major components of MAS, the role of the fibrinolytic system and its key player, plasmin, in the development of MAS remains to be solved. We established a murine model of fulminant MAS by repeated injections of Toll-like receptor-9 (TLR-9) agonist and d-galactosamine (DG) in immunocompetent mice. We found plasmin was excessively activated during the progression of fulminant MAS in mice. Genetic and pharmacological inhibition of plasmin counteracted MAS-associated lethality and other related symptoms. We show that plasmin regulates the influx of inflammatory cells and the production of inflammatory cytokines/chemokines. Collectively, our findings identify plasmin as a decisive checkpoint in the inflammatory response during MAS and a potential novel therapeutic target for MAS.

Transcriptome Analysis on Monocytes from Patients with Neovascular Age-Related Macular Degeneration

Mononuclear phagocytes (MPs), including monocytes/macrophages, play complex roles in age-related macular degeneration (AMD) pathogenesis. We reported altered gene-expression signature in peripheral blood mononuclear cells from AMD patients, and a chemokine receptor signature on AMD monocytes. To obtain comprehensive understanding of MP involvement, particularly in peripheral circulation in AMD, we performed global gene expression analysis in monocytes. We separated monocytes from treatment-naïve neovascular AMD (nvAMD) patients (n = 14) and age-matched controls (n = 15), and performed microarray and bioinformatics analysis. Quantitative real-time PCR was performed on other sets of nvAMD (n = 25), atrophic AMD (n = 21), and controls (n = 28) for validation. This validated microarray genes (like TMEM176A/B and FOSB) tested, including differences between nvAMD and atrophic AMD. We identified 2,165 differentially-expressed genes (P < 0.05), including 79 genes with log2 fold change ≥1.5 between nvAMD and controls. Functional annotation using DAVID and TANGO demonstrated immune response alterations in AMD monocytes (FDR-P <0.05), validated by randomized data comparison (P < 0.0001). GSEA, ISMARA, and MEME analysis found immune enrichment and specific involved microRNAs. Enrichment of differentially-expressed genes in monocytes was found in retina via SAGE data-mining. These genes were enriched in non-classical vs. classical monocyte subsets (P < 0.05). Therefore, global gene expression analysis in AMD monocytes reveals an altered immune-related signature, further implicating systemic MP activation in AMD.

Cancer therapy targeting the fibrinolytic system

The tumor microenvironment is recognized as a key factor in the multiple stages of cancer progression, mediating local resistance, immune-escape and metastasis. Cancer growth and progression require remodeling of the tumor stromal microenvironment, such as the development of tumor-associated blood vessels, recruitment of bone marrow-derived cells and cytokine processing. Extracellular matrix breakdown achieved by proteases like the fibrinolytic factor plasmin and matrix metalloproteases is necessary for cell migration crucial for cancer invasion and metastasis. Key components of the fibrinolytic system are expressed in cells of the tumor microenvironment. Plasmin can control growth factor bioavailability, or the regulation of other proteases leading to angiogenesis, and inflammation. In this review, we will focus on the role of the fibrinolytic system in the tumor microenvironment summarizing our current understanding of the role of the fibrinolytic factors for the modulation of the local chemokine/cytokine milieu, resulting in myeloid cell recruitment, which can promote neoangiogenesis.

Long-term efficacy and downstream mechanism of anti-annexinA2 monoclonal antibody (anti-ANX A2 mAb) in a pre-clinical model of aggressive human breast cancer

There is considerable direct evidence that calcium binding protein ANX A2 is a potential target for treating aggressive breast cancer. The most compelling data are based on the finding of ANX A2 overexpression in aggressive triple negative human breast cancer (TNBC) cell lines and in human breast cancer tissues. Previously, we and others reported a unique role of ANX A2 in cancer invasion, including breast cancer. Moreover, we demonstrated that anti-ANX A2 mAb-mediated immunoneutralization of ANX A2 inhibited invasive human breast cancer growth in a xenograft model. We further evaluated the long-term effects of multiple treatments with anti-ANX A2 mAb and its mechanism of inhibition on human breast tumor growth. We now demonstrate that three treatments with anti-ANX A2 mAb led to significant inhibition of breast tumor growth in immunodeficient mice, and that the anti-tumor response was demonstrable from day 94. After treatment, we followed tumor growth for 172 days and demonstrated 67% inhibition of tumor growth without detectable adverse effects. Biochemical analysis demonstrated that anti-ANX A2 mAb treatment caused significant inhibition of conversion of tissue plasminogen activator (tPA) in the tumor microenvironment. This led to disruption of plasmin generation that consequently inhibited activation of MMP-9 and MMP-2. These results suggest that ANX A2 plays an important role in aggressive breast tumor growth by regulating proteolytic pathways in the tumor microenvironment. ANX A2 may represent a new target for the development of therapeutics for treatment of aggressive breast cancer.

Tranexamic acid in trauma: how should we use it?

Tranexamic acid (TXA) reduces blood loss by inhibiting the enzymatic breakdown of fibrin. It is often used in surgery to decrease bleeding and the need for blood transfusion. In 2011, results from a multi-center, randomized, and placebo-controlled trial (CRASH-2 trial) showed that TXA (1 g loading dose over 10 min followed by an infusion of 1 g over 8 h) safely reduces mortality in bleeding trauma patients. Initiation of TXA treatment within 3 h of injury reduces the risk of hemorrhage death by about one-third, regardless of baseline risk. Because it does not have any serious adverse effects, TXA can be administered to a wide spectrum of bleeding trauma patients. Limiting its use to the most severely injured or those with a diagnosis of 'hyperfibrinolysis' would result in thousands of avoidable deaths. A clinical trial (CRASH-3 trial) of TXA in patients with traumatic brain injury is now in progress.