Antiinflammatory activity of tissue plasminogen activator in the carrageenan rat footpad model

Pharmacotherapy consideration of thrombolytic medications in COVID-19-associated ARDS

BACKGROUND

In late 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which is responsible for coronavirus disease (COVID-19), was identified as the new pathogen to lead pneumonia in Wuhan, China, which has spread all over the world and developed into a pandemic. Despite the over 1 year of pandemic, due to the lack of an effective treatment plan, the morbidity and mortality of COVID-19 remains high. Efforts are underway to find the optimal management for this viral disease.

MAIN BODY

SARS-CoV-2 could simultaneously affect multiple organs with variable degrees of severity, from mild to critical disease. Overproduction of pro-inflammatory mediators, exacerbated cellular and humoral immune responses, and coagulopathy such as Pulmonary Intravascular Coagulopathy (PIC) contributes to cell injuries. Considering the pathophysiology of the disease and multiple microthrombi developments in COVID-19, thrombolytic medications seem to play a role in the management of the disease. Beyond the anticoagulation, the exact role of thrombolytic medications in the management of patients with COVID-19-associated acute respiratory distress syndrome (ARDS) is not explicit. This review focuses on current progress in underlying mechanisms of COVID-19-associated pulmonary intravascular coagulopathy, the historical use of thrombolytic drugs in the management of ARDS, and pharmacotherapy considerations of thrombolytic therapy, their possible benefits, and pitfalls in COVID-19-associated ARDS.

CONCLUSIONS

Inhaled or intravenous administration of thrombolytics appears to be a salvage therapy for severe ARDS associated with COVID-19 by prompt attenuation of lung injury. Considering the pathogenesis of COVID-19-related ARDS and mechanism of action of thrombolytic agents, thrombolytics appear attractive options in stable patients without contraindications.

Integrating Non-human Primate, Human, and Mathematical Studies to Determine the Influence of BCG Timing on H56 Vaccine Outcomes

Background

Acute lung injury (ALI) is characterized by suppressed fibrinolytic activity in bronchoalveolar lavage fluid (BALF) attributed to elevated plasminogen activator inhibitor-1 (PAI-1). Restoring pulmonary fibrinolysis by delivering tissue-type plasminogen activator (tPA), urokinase plasminogen activator (uPA), and plasmin could be a promising approach.

Objectives

To systematically analyze the overall benefit of fibrinolytic therapy for ALI reported in preclinical studies.

Methods

We searched PubMed, Embase, Web of Science, and CNKI Chinese databases, and analyzed data retrieved from 22 studies for the beneficial effects of fibrinolytics on animal models of ALI.

Results

Both large and small animals were used with five routes for delivering tPA, uPA, and plasmin. Fibrinolytics significantly increased the fibrinolytic activity both in the plasma and BALF. Fibrin degradation products in BALF had a net increase of 408.41 ng/ml vs controls (P < 0.00001). In addition, plasma thrombin–antithrombin complexes increased 1.59 ng/ml over controls (P = 0.0001). In sharp contrast, PAI-1 level in BALF decreased 21.44 ng/ml compared with controls (P < 0.00001). Arterial oxygen tension was improved by a net increase of 15.16 mmHg, while carbon dioxide pressure was significantly reduced (11.66 mmHg, P = 0.0001 vs controls). Additionally, fibrinolytics improved lung function and alleviated inflammation response: the lung wet/dry ratio was decreased 1.49 (P < 0.0001 vs controls), lung injury score was reduced 1.83 (P < 0.00001 vs controls), and BALF neutrophils were lesser (3 × 10⁴/ml, P < 0.00001 vs controls). The mortality decreased significantly within defined study periods (6 h to 30 days for mortality), as the risk ratio of death was 0.2-fold of controls (P = 0.0008).

Conclusion

We conclude that fibrinolytic therapy may be effective pharmaceutic strategy for ALI in animal models.

Aptamer-Based Proteomics Identifies Mortality-Associated Serum Biomarkers in Dialysis-Dependent AKI Patients

Introduction

Currently, no effective therapies exist to reduce the high mortality associated with dialysis-dependent acute kidney injury (AKI-D). Serum biomarkers may be useful in understanding the pathophysiological processes involved with AKI and the severity of injury, and point to novel therapeutic targets.

Methods

Study day 1 serum samples from 100 patients and day 8 samples from 107 patients enrolled in the Veteran’s Affairs/National Institutes of Health Acute Renal Failure Trial Network study were analyzed by the slow off-rate modified aptamers scan proteomic platform to profile 1305 proteins in each sample. Patients in each cohort were classified into tertiles based on baseline biomarker measurements. Cox regression analyses were performed to examine the relationships between serum levels of each biomarker and mortality.

Results

Changes in the serum levels of 54 proteins, 33 of which increased and 21 of which decreased, were detected when comparing samples of patients who died in the first 8 days versus patients who survived >8 days. Among the 33 proteins that increased, higher serum levels of fibroblast growth factor-23 (FGF23), tissue plasminogen activator (tPA), neutrophil collagenase (matrix metalloproteinase-8), and soluble urokinase plasminogen activator receptor, when stratified by tertiles, were associated with higher mortality. The association with mortality persisted for each of these proteins after adjusting for other potential risk factors, including age, sex, cardiovascular sequential organ failure assessment score, congestive heart failure, and presence of diabetes. Upper tertile levels of FGF23, tPA, and interleukin-6 on day 8 were associated with increased mortality; however, FGF23 barely lost significance after multivariable adjustment.

Conclusions

Our results underscore an emerging proteomics tool capable of identifying low-abundance serum proteins important not only in the pathogenesis of AKI-D, but which is also helpful in discriminating AKI-D patients with high mortality.

Anticoagulant therapy in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) presents a complex pathophysiology characterized by pulmonary activated coagulation and reduced fibrinolysis. Despite advances in supportive care of this syndrome, morbidity and mortality remains high, leading to the need of novel therapies to combat this disease. Focus these therapies in the inhibition of ARDS development pathophysiology is essential. Beneficial effects of anticoagulants in ARDS have been proved in preclinical and clinical trials, thanks to its anticoagulant and anti-inflammatory properties. Moreover, local administration by nebulization in the alveolar compartment increases local efficacy and does not produce systemic bleeding. In this review the coagulation and fibrinolytic pathway and its pharmacological targets to treat ARDS are summarized.

Thrombus Degradation by Fibrinolytic Enzyme of Stenotrophomonas sp. Originated from Indonesian Soybean-Based Fermented Food on Wistar Rats

Objective. To evaluate thrombus degrading effect of a fibrinolytic enzyme from food origin Stenotrophomonas sp. of Indonesia. Methods. Prior to animal study, the enzyme safety was tested using cell culture. The effect on expression of tissue plasminogen activator was also analysed in the cell culture. For in vivo studies, 25 Wistar rats were used: normal control, negative control, treatment groups with crude and semipurified enzyme given orally at 25 mg/kg, and positive control group which received Lumbrokinase at 25 mg/kg. Blood clot in the tail was induced by kappa carrageenan injection at 1 mg/kg BW. Results. Experiment with cell culture confirmed the enzyme safety at the concentration used and increased expression of tPA. Decreasing of thrombus was observed in the positive group down to 70.35 ± 23.11% of the negative control animals (100%). The thrombus observed in the crude enzyme treatment was down to 56.99 ± 15.95% and 71.5 ± 15.7% for semipurified enzyme. Scanning electron microscopy showed clearly that bood clots were found in the animals injected with kappa carrageenan; however, in the treatment and positive groups, the clot was much reduced. Conclusions. Oral treatment of enzyme from Stenotrophomonas sp. of Indonesian fermented food was capable of degrading thrombus induced in Wistar rats.

Adenosine potentiates human lung mast cell tissue plasminogen activator activity

We investigated whether adenosine, a potent contributor to the regulation of pulmonary function, can modulate human lung mast cell (HLMC) fibrinolytic activity. Tissue plasminogen activator (tPA) activity and tPA transcript expression levels from a human mast cell line (HMC-1) and HLMC were monitored following adenosine application. Adenosine potentiated mast cell tPA activity and tPA gene expression in a dose-dependent manner. Adenosine effects were abolished in the presence of adenosine deaminase. HMC-1 cells and HLMC predominantly expressed adenosine A(2A) and A(2B) receptor transcripts (A(2B) ≈ A(2A) > A(3) >> A(1)). Pharmacological and signaling studies suggest that the A(2A) receptor is the major subtype accounting for adenosine-induced mast cell tPA activity. Finally, the supernatant from HMC-1 cells and HLMC treated with adenosine (for 24 h) significantly increased fibrin clot lysis, whereas ZM241385, an A(2A) receptor antagonist, abolished this effect. To our knowledge, this study provides the first data to demonstrate the potentiating effect of adenosine on mast cell tPA activity and fibrin clot lysis.

A review of pulmonary coagulopathy in acute lung injury, acute respiratory distress syndrome and pneumonia

Enhanced bronchoalveolar coagulation is a hallmark of many acute inflammatory lung diseases such as acute lung injury, acute respiratory distress syndrome and pneumonia. Intervention with natural anticoagulants in these diseases has therefore become a topic of interest. Recently, new data on the role of pulmonary coagulation and inflammation has become available. The aim of this review is to summarize these findings. Furthermore, the results of anticoagulant therapeutic interventions in these disorders are discussed.

Endogenous tissue-type plasminogen activator is protective during ascending urinary tract infection

BACKGROUND

Acute pyelonephritis is one of the most common bacterial infections. Tissue-type plasminogen activator (tPA) is a potent fibrinolytic agent, but can play a role in inflammatory processes as well.

METHODS

We induced pyelonephritis in tPA(-/-) and C57BL/6 wild-type (WT) mice by intravesical inoculation with 10(10) CFU uropathogenic Escherichia coli 1677. The mice were killed after 24 and 48 h, after which bacterial outgrowth and cytokine levels in kidney homogenates were determined. Influx of neutrophils was quantified by myeloperoxidase-ELISA. Neutrophil phagocytosis and oxidative burst were measured.

RESULTS

The tPA(-/-) kidneys contained significantly higher numbers of E. coli CFU, accompanied by higher levels of interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha). The number of infiltrating neutrophils was similar in tPA(-/-) and WT mice at both time points, suggesting that tPA(-/-) neutrophils have a lower ability to eliminate E. coli. Phagocytosis of E. coli organisms was not diminished in tPA(-/-) neutrophils. Interestingly, tPA(-/-) neutrophils showed a significantly lower ability to generate an oxidative burst reaction upon stimulation with E. coli than WT neutrophils. Incubation with recombinant tPA reversed this effect completely.

CONCLUSIONS

These results show that deletion of the tPA-gene in mice leads to lower bactericidal potential of tPA(-/-) neutrophils, which results in significantly more bacterial outgrowth during experimental pyelonephritis.

Accelerated dosing frequency of a pulmonary formulation of tissue plasminogen activator is well-tolerated in mice

1. Tissue plasminogen activator (tPA) has both fibrinolytic and anti-inflammatory activity. These properties may be useful in treating inflammatory lung diseases, such as acute respiratory distress syndrome (ARDS). 2. We have previously demonstrated the feasibility of targeted pulmonary delivery of tPA. As part of our research to develop a clinically viable pulmonary formulation of tPA, we assessed the tolerability and incidence of haemorrhage associated with the administration of a pulmonary formulation of mouse tPA (pf-mtPA). 3. Intratracheal doses of nebulized pf-mtPA or sterile saline were administered with increasing frequency to male and female B6C3F1 mice. After dosing, the mice entered a recovery period, after which they were killed and their lungs were lavaged and harvested. Post-mortem gross necropsy was performed and all major organs were assessed histologically for haemorrhage. The bronchoalveolar lavage fluid was assessed for markers of lung injury. 4. Mouse tPA that was formulated to mimic a previously characterized human pf-tPA was well tolerated when given intratracheally with increasing dosing frequency. The administration of pf-mtPA did not result in any detectable haemorrhagic-related events or signs of lung injury. 5. The results of the present longitudinal study demonstrate that a maximally feasible dose of pf-mtPA (3 mg/kg) can be given frequently over a short period of time (12 h) without haemorrhagic complications. Although these data were generated in a healthy mouse model, they provide support for the continued evaluation of pf-tPA for the treatment of pulmonary diseases, such as ARDS.

The involvement of AMP-activated protein kinases in the anti-inflammatory effect of nicotine in vivo and in vitro

AMP-activated protein kinase (AMPK) is the downstream component of a kinase cascade that plays a pivotal role in energy homeostasis. AMPK has recently emerged as an attractive and novel target for inflammatory disorders. Thus, the aim of this study was to assess the role of AMPKalpha in the anti-inflammatory effect of nicotine in carrageenan-induced rat paw edema model and to evaluate the mechanism of nicotine-induced AMPKalpha phosphorylation in RAW 264.7 cells. The results indicate that nicotine alleviated paw edema and the activation of AMPKalpha involved in the anti-inflammatory effect of nicotine in vivo. In addition, nicotine was able to activate AMPKalpha phosphorylation in macrophages and this effect was mediated through nicotinic acetylcholine receptors. Furthermore, nicotine significantly induced the phosphorylation of Akt and the Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) protein expression in macrophages. Wortmannin, a specific inhibitor of phosphotidylinositol 3-kinase (PI3K), suppressed nicotine-induced Akt and AMPKalpha phosphorylation. STO-609, a CaMKK inhibitor, not only inhibited the activation of AMPKalpha but also suppressed the phosphorylation of Akt induced by nicotine. In conclusion, both of CaMKK and PI3K/Akt pathways are involved in the nicotine-induced AMPKalpha phosphorylation in macrophages, and the interaction of CaMKK and Akt may exist. AMPKalpha is a novel and critical component of anti-inflammatory effect of nicotine.

Emerging role of anticoagulants and fibrinolytics in the treatment of acute respiratory distress syndrome

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are associated with high mortality rates despite therapeutic advances. The pathogenesis of ALI and ARDS is similar to that of sepsis, as these disease states involve uncontrolled host defense responses that lead to inflammation, endothelial damage, enhanced coagulation, diminished fibrinolysis, and fibroproliferation. Recent studies of anticoagulants have shown positive outcomes in patients with severe sepsis. In addition, emerging evidence suggests that the use of anticoagulants, such as tissue factor pathway inhibitor, antithrombin, thrombomodulin, heparin, activated protein C, and fibrinolytics (plasminogen activators and particularly tissue plasminogen activator), may be useful in the treatment of ALI and ARDS. Data from experimental models of sepsis, ALI, and ARDS indicate that some of these agents improve lung function and oxygenation. Although clinical data are less convincing than these findings, results from clinical trials may influence the design of future studies.

Tissue-type plasminogen activator modulates inflammatory responses and renal function in ischemia reperfusion injury

Acute renal failure is often the result of ischemia-reperfusion (I/R) injury. Neutrophil influx is an important damaging event in I/R. Tissue-type plasminogen activator (tPA) not only is a major fibrinolytic agent but also is involved in inflammatory processes. A distinct upregulation of tPA after I/R, with de novo tPA production by proximal renal tubules, was found. For investigating the role of tPA in I/R, renal ischemia was induced in tPA-/- and wild-type (WT) mice by clamping both renal arteries for 35 min followed by reperfusion. Mice were killed 1, 5, and 10 d after reperfusion. After 1 d, tPA-/- mice displayed significantly less neutrophil influx into the interstitial area compared with WT mice. In addition, tPA-/- mice showed quicker recovery of renal function than WT mice. The protocol was repeated after injection of tPA-antisense oligonucleotides into WT mice, leading to even more explicit results: Antisense-treated mice showed less histologic damage, better renal function, and less neutrophil influx than control mice. Surprising, complement C3 concentration, levels of proinflammatory cytokines and chemokines, intercellular adhesion molecule-1 expression, and matrix metalloproteinase activity were similar in WT and tPA-/- mice. Plasmin activity levels in WT and tPA-/- kidneys were also comparable, indicating that tPA influences neutrophil influx into ischemic renal tissue independent from plasmin generation. This study shows that targeting tPA could be of therapeutic importance in treating I/R injury by diminishing neutrophil influx and preserving renal function.

Study of the inflammatory process induced by injection of carrageenan or formalin in the rat temporomandibular joint

The aim of this study was to evaluate the effects of the injection of two phlogistic agents, carrageenan and formalin, in the rat TMJ, and the inflammatory process induced by these substances. In this study, a total of 45 adult rats were distributed in two experimental groups and a control group. The animals were sacrificed after three hours, 24 hours, three days, seven days, and 15 days after a single injection of each substance. Histological data initially demonstrated an inflammatory process represented by acute infiltration, which later became mixed, and finally chronic in both experimental groups. Hyperplasia of the synovial membrane was observed after three days, being intense at seven days, and present after 15 days only in the formalin group. Local saline injection in the control group caused no inflammatory reaction. It was concluded that a single local injection of carrageenan or formalin was enough to induce inflammatory reaction in the TMJ and periarticular soft tissues, and that the resulting processes were similar, but more persistent in the formalin group.

ADMINISTRATION OF EXOGENOUS TISSUE PLASMINOGEN ACTIVATOR REDUCES OEDEMA IN MICE LACKING THE TISSUE PLASMINOGEN ACTIVATOR GENE

It has recently become apparent that tissue plasminogen activator (tPA) modulates inflammation in diseases such as rheumatoid arthritis (RA) and acute respiratory distress syndrome (ARDS). We have shown previously that tPA has anti-inflammatory activity in in vivo models of oedema or inflammation. The present study investigated the ability of exogenous recombinant tPA (rtPA) to reduce carrageenan-mediated oedema in mice lacking the tPA gene, testing the hypothesis that rtPA treatment may be beneficial in diseases such as RA and ARDS in which there is a paucity of endogenous tPA. Knockout mice deficient in the tPA gene and matching wild-type mice received an intraplantar injection (25 micro L) of carrageenan (1.5%, w/v) following either vehicle (sterile water for injection) or tPA (12 mg/kg). Footpad oedema was measured, an oedema index was calculated and tissue myeloperoxidase (MPO) activity was determined. Mean oedema indices were higher in untreated tPA (-/-) mice than untreated wild-type mice. Pretreatment with rtPA in either tPA (-/-) or wild-type mice reduced the mean measured peak footpad oedema index by 63 and 48%, respectively. Tissue MPO activity was not different between treatment groups. We conclude that exogenous rtPA has the ability to reduce acute oedema without altering neutrophil infiltration into the site of injury in both tPA (-/-) and wild-type mice and that endogenous tPA may participate in the inflammatory process, as evidenced by higher oedema indices in untreated tPA (-/-) mice. These data provide support for the potential clinical utility of exogenous rtPA in the treatment of inflammatory diseases, such as RA and ARDS, in which there is a paucity of tPA.

Differing roles for urokinase and tissue-type plasminogen activator in collagen-induced arthritis

The plasminogen activators, urokinase PA (u-PA) and tissue-type PA (t-PA), are believed to play important roles in inflammatory cell infiltration, fibrin deposition, and joint destruction associated with rheumatoid arthritis; however, their precise roles in such processes, particularly u-PA, have yet to be defined. Using gene-deficient mice we examined the relative contribution of the PAs to the chronic systemic collagen-induced arthritis model. Based on clinical and histological assessments, u-PA-/- mice developed significantly milder disease and t-PA-/- mice more severe disease compared with the relevant wild-type mice. Fibrin deposition within joints paralleled disease severity and was particularly pronounced in t-PA-/- mice. Likewise, cytokine levels in the synovium reflected the severity of disease, with interleukin-1beta levels in particular being lower in u-PA-/- mice and increased in t-PA-/- mice. The antibody response to type II collagen was normal in both knockouts; however, T cells from u-PA-/- mice had a reduced proliferative response and produced less interferon-gamma on antigen stimulation in vitro. These results indicate that the major effect of u-PA in the collagen-induced arthritis model is deleterious, whereas that of t-PA is protective. Our data highlight the complexities of PA function, and suggest that approaches either to target u-PA or to enhance local t-PA activity in joints may be of therapeutic benefit in rheumatoid arthritis.

Identification of genes induced by inflammatory cytokines in airway epithelium

Epithelial cells lining the airways are thought to play a prominent role in respiratory diseases. We utilized cDNA representational difference analysis to identify the genes in which expression is induced by the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta in primary human bronchial epithelial cells and hence are relevant to airway inflammation. Hybridization of the subtraction product to arrayed cDNAs indicated that known tumor necrosis factor-alpha- and interleukin-1beta-inducible genes such as B94, Zfp36, and regulated on activation normal T cell expressed and secreted were represented, confirming the success of the subtraction experiment. A 1,152-clone library potentially representing genes with higher transcript levels in cytokine-treated human bronchial epithelial cells was generated and sequenced. Sequence similarity searches indicated that these clones represented 57 genes of known function, 1 gene of unknown function, 6 expressed sequence tags, and 2 novel sequences. The expression of 19 of these clones was studied by a combination of Northern blotting and RT-PCR analyses and confirmation of differential expression for 10 known genes, 2 expressed sequence tags, and a novel sequence not represented in any of the public databases was obtained. Thus cDNA representational difference analysis was utilized to isolate known and novel differentially expressed genes, which putatively play a role in airway inflammation.

Tissue plasminogen activator inhibits reactive oxygen species production by macrophages

STUDY OBJECTIVE

To determine whether tissue plasminogen activator (tPA) alters macrophage reactive oxygen species (ROS) production.

INTERVENTION

Cultured macrophages were exposed to either phorbol myristate acetate (PMA) or zymosan (ZMA) after a 1-hour incubation with either tPA 100 microg/ml or L-arginine 3.5 mg/ml, an excipient used in the formulation of tPA.

MEASUREMENTS AND MAIN RESULTS

Production of ROS was measured using chemiluminescence (CL). Tissue plasminogen activator reduced the mean peak CL of macrophages exposed to PMA or ZMA by 20% and 36%, respectively (p=0.0008 and p=0.028, analysis of variance). L-arginine had no effect on either PMA- or ZMA-induced macrophage CL.

CONCLUSION

Our results suggest that tPA has broad inhibitory effects on inflammatory cell ROS production. In diseases such as atherosclerosis and acute respiratory distress syndrome, these data suggest the possible utility of exogenous tPA as an antiinflammatory agent and a physiologic role for endogenous tPA that goes beyond maintenance of homeostasis.

Tissue plasminogen activator (tPA) inhibits interleukin-1 induced acute lung leak

Because plasminogen activators (PA) may participate in the inflammatory process associated with the acute respiratory distress syndrome (ARDS), we measured the effect of tissue plasminogen activator (tPA) on inflammation and acute lung leak caused by intratracheal instillation of IL-1alpha (50 ng) into male (300-400 g) Sprague-Dawley rats. Lung leak, lung myeloperoxidase (MPO) activity, and lung lavage neutrophil counts were increased in rats given IL-1 intratracheally compared to control rats that were given saline intratracheally. Giving tPA (12 mg/kg) intraperitoneally increased lung tPA concentration and reduced acute lung leak in rats given IL-1 intratracheally (p < .01; lung leak index for sham-treated rats: 0.040 + 0.001, n=6; IL-1: 0.10 + 0.01, n=10; tPA + IL-1: 0.050 + 0.002, n=6). In contrast, administering tPA did not change IL-1-induced increases in lung lavage neutrophils or lung MPO activity (sham: 0.003 x 106 + 0.001 x 10(6) cells; IL-1: 2.9 x 10(6) + 0.4 x 10(6) cells; tPA + IL-1: 2.7 x 10(6) + 0.4 x 10(6) cells; and sham: 0.6 + 0.2 U/g lung; IL-1: 11.2 + 2.9 U/g lung, tPA + IL-1: 11.1 + 1.6 U/g lung, respectively). Our results suggest that intraperitoneal tPA administration increases lung tissue tPA levels and decreases acute lung leak without reducing lung neutrophil infiltration in rats given IL-1alpha intratracheally. This work suggests that tPA may suppress neutrophil activation in vivo and accordingly have anti-inflammatory effects.