Plasminogen: an enigmatic zymogen

Blood ◽  
2021 ◽  
Author(s):  
Charithani B Keragala ◽  
Robert L Medcalf
Keyword(s):  
Animal Studies ◽  
Wound Repair ◽  
Active Form ◽  
Cell Behaviour ◽  
Surface Receptors ◽  
Enzymatic Cascades ◽  
Inflammatory Processes ◽  
Over 40 Years

Plasminogen is an abundant plasma protein that exists in various zymogenic forms. Plasmin, the proteolytically active form of plasminogen, is known for its essential role in fibrinolysis. The therapeutic targeting of the fibrinolytic system to date has been for two purposes: to promote plasmin generation for thromboembolic conditions, or to stop plasmin to reduce bleeding. However, both plasmin and plasminogen serve other important functions, some of which are unrelated to fibrin removal. Indeed, for over 40 years, the anti-fibrinolytic agent, tranexamic acid, has been administered for its serendipitously discovered skin whitening properties. Plasmin also plays an important role in the removal of misfolded/aggregated proteins and can trigger other enzymatic cascades including complement. In addition, plasminogen, via binding to one of its dozen cell-surface receptors, can modulate cell behaviour and further influence immune and inflammatory processes. Plasminogen administration itself has been reported to improve thrombolysis and to accelerate wound repair. While many of these more recent findings have been derived from in vitro or animal studies, the use of anti-fibrinolytics to reduce bleeding in humans has revealed additional clinically relevant consequences, particularly in relation to reducing infection risk that is independent of its haemostatic effects. The finding that many viruses harness the host plasminogen to aid infectivity has suggested that anti-fibrinolytic agents may have anti-viral benefits. Here we review the broadening role of the plasminogen activating system in physiology and pathophysiology and how manipulation of this system may be harnessed for benefits unrelated to its conventional application in thrombosis and haemostasis.

scholarly journals Oxidative Stress as a Possible Target in the Treatment of Toxoplasmosis: Perspectives and Ambiguities

2021 ◽  
Vol 22 (11) ◽  
pp. 5705
Author(s):  
Karolina Szewczyk-Golec ◽  
Marta Pawłowska ◽  
Roland Wesołowski ◽  
Marcin Wróblewski ◽  
Celestyna Mila-Kierzenkowska
Keyword(s):  
Oxidative Stress ◽  
Animal Studies ◽  
Treatment Options ◽  
Natural Antioxidants ◽  
Redox Status ◽  
Host Cells ◽  
Common Disease ◽  
Parasite Viability

Toxoplasma gondii is an apicomplexan parasite causing toxoplasmosis, a common disease, which is most typically asymptomatic. However, toxoplasmosis can be severe and even fatal in immunocompromised patients and fetuses. Available treatment options are limited, so there is a strong impetus to develop novel therapeutics. This review focuses on the role of oxidative stress in the pathophysiology and treatment of T. gondii infection. Chemical compounds that modify redox status can reduce the parasite viability and thus be potential anti-Toxoplasma drugs. On the other hand, oxidative stress caused by the activation of the inflammatory response may have some deleterious consequences in host cells. In this respect, the potential use of natural antioxidants is worth considering, including melatonin and some vitamins, as possible novel anti-Toxoplasma therapeutics. Results of in vitro and animal studies are promising. However, supplementation with some antioxidants was found to promote the increase in parasitemia, and the disease was then characterized by a milder course. Undoubtedly, research in this area may have a significant impact on the future prospects of toxoplasmosis therapy.

H2O2 inhibits alveolar epithelial wound repair in vitro by induction of apoptosis

2004 ◽  
Vol 287 (2) ◽  
pp. L448-L453 ◽  
Author(s):  
Thomas Geiser ◽  
Masanobu Ishigaki ◽  
Coretta van Leer ◽  
Michael A. Matthay ◽  
V. Courtney Broaddus
Keyword(s):  
Acute Lung Injury ◽  
Epithelial Cells ◽  
Lung Injury ◽  
Cell Viability ◽  
Wound Repair ◽  
Wound Edge ◽  
Alveolar Epithelial ◽  
Induction Of Apoptosis

Reactive oxygen species (ROS) are released into the alveolar space and contribute to alveolar epithelial damage in patients with acute lung injury. However, the role of ROS in alveolar repair is not known. We studied the effect of ROS in our in vitro wound healing model using either human A549 alveolar epithelial cells or primary distal lung epithelial cells. We found that H2O2 inhibited alveolar epithelial repair in a concentration-dependent manner. At similar concentrations, H2O2 also induced apoptosis, an effect seen particularly at the edge of the wound, leading us to hypothesize that apoptosis contributes to H2O2-induced inhibition of wound repair. To learn the role of apoptosis, we blocked caspases with the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). In the presence of H2O2, zVAD inhibited apoptosis, particularly at the wound edge and, most importantly, maintained alveolar epithelial wound repair. In H2O2-exposed cells, zVAD also maintained cell viability as judged by improved cell spreading and/or migration at the wound edge and by a more normal mitochondrial potential difference compared with cells not treated with zVAD. In conclusion, H2O2 inhibits alveolar epithelial wound repair in large part by induction of apoptosis. Inhibition of apoptosis can maintain wound repair and cell viability in the face of ROS. Inhibiting apoptosis may be a promising new approach to improve repair of the alveolar epithelium in patients with acute lung injury.

scholarly journals Subinhibitory Antimicrobial Concentrations: A Review of In Vitro and In Vivo Data

1992 ◽  
Vol 3 (4) ◽  
pp. 193-201 ◽  
Author(s):  
George G Zhanel ◽  
Daryl J Hoban ◽  
Godfrey KM Harding
Keyword(s):  
Antimicrobial Activity ◽  
Animal Studies ◽  
Molecular Level ◽  
Bacterial Virulence ◽  
Antibacterial Effects ◽  
Wide Range ◽  
Immune Defences

Antimicrobial activity is not an ‘all or none’ effect. An increase in the rate and extent of antimicrobial action is usually observed over a wide range of antimicrobial concentrations. Subinhibitory antimicrobial concentrations are well known to produce significant antibacterial effects, and various antimicrobials at subinhibitory concentrations have been reported to inhibit the rate of bacterial growth. Bacterial virulence may be increased or decreased by subinhibitory antimicrobial concentrations by changes in the ability of bacteria to adhere to epithelial cells or by alterations in bacterial susceptibility to host immune defences. Animal studies performed in rats, hamsters and rabbits demonstrate decreased bacterial adherence, reduced infectivity and increased survival of animals treated with subinhibitory antimicrobial concentrations compared to untreated controls. The major future role of investigation of subinhibitory antimicrobial concentrations will be to define more fully, at a molecular level, how antimicrobials exert their antibacterial effects.

Vagus Nerve Stimulation

2018 ◽  
Vol 3 (2) ◽  
pp. 54-58
Author(s):  
Eric J. Yang ◽  
Sahil Sekhon ◽  
Kristen M. Beck ◽  
Isabelle M. Sanchez ◽  
Tina Bhutani ◽  
...  
Keyword(s):  
Psoriatic Arthritis ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Animal Studies ◽  
Chronic Inflammatory Disease ◽  
Inflammatory Processes ◽  
Current Therapies ◽  
Inflammatory Bowel

Treatments for psoriasis and psoriatic arthritis have progressed at a rapid rate over the past 20 years, but treating patients with recalcitrant disease still remains a difficult task. Current therapies for these diseases involve topical agents, phototherapy, and systemic immunosuppression. However, the role of the nervous system in psoriasis and psoriatic arthritis remains largely unexplored. Recent animal studies and clinical trials have demonstrated that vagus nerve stimulation can decrease inflammatory processes in rheumatoid arthritis and inflammatory bowel disease. In this article, we outline the existing knowledge of the nervous system’s role in chronic inflammatory disease and discuss how these findings could be utilized in the future for treatment of psoriasis and psoriatic arthritis.

Advances in microglia cellular models: focus on extracellular vesicle production

2021 ◽  
Author(s):  
Lorenzo Ceccarelli ◽  
Laura Marchetti ◽  
Chiara Giacomelli ◽  
Claudia Martini
Keyword(s):  
Cell Communication ◽  
Extracellular Vesicle ◽  
Cellular Models ◽  
Advantages And Disadvantages ◽  
Inflammatory Processes ◽  
The Central Nervous System ◽  
Harmful Effects ◽  
Brain Homeostasis

Microglia are the major component of the innate immune system in the central nervous system. They promote the maintenance of brain homeostasis as well as support inflammatory processes that are often related to pathological conditions such as neurodegenerative diseases. Depending on the stimulus received, microglia cells dynamically change their phenotype releasing specific soluble factors and largely modify the cargo of their secreted extracellular vesicles (EVs). Despite the mechanisms at the basis of microglia actions have not been completely clarified, the recognized functions exerted by their EVs in patho-physiological conditions represent the proof of the crucial role of these organelles in tuning cell-to-cell communication, promoting either protective or harmful effects. Consistently, in vitro cell models to better elucidate microglia EV production and mechanisms of their release have been increased in the last years. In this review, the main microglial cellular models that have been developed and validated will be described and discussed, with particular focus on those used to produce and derive EVs. The advantages and disadvantages of their use will be evidenced too. Finally, given the wide interest in applying EVs in diagnosis and therapy too, the heterogeneity of available models for producing microglia EVs is here underlined, to prompt a cross-check or comparison among them.

scholarly journals Ozone Therapy as Adjuvant for Cancer Treatment: Is Further Research Warranted?

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Bernardino Clavo ◽  
Norberto Santana-Rodríguez ◽  
Pedro Llontop ◽  
Dominga Gutiérrez ◽  
Gerardo Suárez ◽  
...  
Keyword(s):  
Cancer Treatment ◽  
Immune Modulation ◽  
Animal Studies ◽  
Potential Role ◽  
Randomized Clinical Trials ◽  
Tumor Hypoxia ◽  
Tumor Resection ◽  
Ozone Therapy

Introduction. This article provides an overview of the potential use of ozone as an adjuvant during cancer treatment.Methods. We summarize the findings of the most relevant publications focused on this goal, and we include our related clinical experience.Results. Over several decades, prestigious journals have publishedin vitrostudies on the capacity of ozone to induce direct damage on tumor cells and, as well, to enhance the effects of radiotherapy and chemotherapy. Indirect effects have been demonstrated in animal models: immune modulation by ozone alone and sensitizing effect of radiotherapy by concurrent ozone administration. The effects of ozone in modifying hemoglobin dissociation curve, 2,3-diphosphoglycerate levels, locoregional blood flow, and tumor hypoxia provide additional support for potential beneficial effects during cancer treatment. Unfortunately, only a few clinical studies are available. Finally, we describe some works and our experience supporting the potential role of local ozone therapy in treating delayed healing after tumor resection, to avoid delays in commencing radiotherapy and chemotherapy.Conclusions.In vitroand animal studies, as well as isolated clinical reports, suggest the potential role of ozone as an adjuvant during radiotherapy and/or chemotherapy. However, further research, such as randomized clinical trials, is required to demonstrate its potential usefulness as an adjuvant therapeutic tool.

scholarly journals Mast Cells in Cardiovascular Disease: From Bench to Bedside

2019 ◽  
Vol 20 (14) ◽  
pp. 3395 ◽  
Author(s):  
Hermans ◽  
Lennep ◽  
van Daele ◽  
Bot
Keyword(s):  
Cardiovascular Disease ◽  
Mast Cells ◽  
Animal Studies ◽  
Intraplaque Hemorrhage ◽  
Hematological Disease ◽  
Plaque Instability ◽  
Clonal Proliferation ◽  
Progression Of Atherosclerosis

Mast cells are pluripotent leukocytes that reside in the mucosa and connective tissue. Recent studies show an increased prevalence of cardiovascular disease among patients with mastocytosis, which is a hematological disease that is characterized by the accumulation of mast cells due to clonal proliferation. This association suggests an important role for mast cells in cardiovascular disease. Indeed, the evidence establishing the contribution of mast cells to the development and progression of atherosclerosis is continually increasing. Mast cells may contribute to plaque formation by stimulating the formation of foam cells and causing a pro-inflammatory micro-environment. In addition, these cells are able to promote plaque instability by neo-vessel formation and also by inducing intraplaque hemorrhage. Furthermore, mast cells appear to stimulate the formation of fibrosis after a cardiac infarction. In this review, the available data on the role of mast cells in cardiovascular disease are summarized, containing both in vitro research and animal studies, followed by a discussion of human data on the association between cardiovascular morbidity and diseases in which mast cells are important: Kounis syndrome, mastocytosis and allergy.

scholarly journals Tendon Extracellular Matrix Remodeling and Defective Cell Polarization in the Presence of Collagen VI Mutations

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 409 ◽  
Author(s):  
Manuela Antoniel ◽  
Francesco Traina ◽  
Luciano Merlini ◽  
Davide Andrenacci ◽  
Domenico Tigani ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Critical Role ◽  
Active Form ◽  
Congenital Muscular Dystrophy ◽  
Cell Polarization ◽  
Pcr Analysis ◽  
Matrix Remodeling ◽  
Collagen Vi

Mutations in collagen VI genes cause two major clinical myopathies, Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD), and the rarer myosclerosis myopathy. In addition to congenital muscle weakness, patients affected by collagen VI-related myopathies show axial and proximal joint contractures, and distal joint hypermobility, which suggest the involvement of tendon function. To gain further insight into the role of collagen VI in human tendon structure and function, we performed ultrastructural, biochemical, and RT-PCR analysis on tendon biopsies and on cell cultures derived from two patients affected with BM and UCMD. In vitro studies revealed striking alterations in the collagen VI network, associated with disruption of the collagen VI-NG2 (Collagen VI-neural/glial antigen 2) axis and defects in cell polarization and migration. The organization of extracellular matrix (ECM) components, as regards collagens I and XII, was also affected, along with an increase in the active form of metalloproteinase 2 (MMP2). In agreement with the in vitro alterations, tendon biopsies from collagen VI-related myopathy patients displayed striking changes in collagen fibril morphology and cell death. These data point to a critical role of collagen VI in tendon matrix organization and cell behavior. The remodeling of the tendon matrix may contribute to the muscle dysfunction observed in BM and UCMD patients.

scholarly journals The Inhibitory Role of Rab11b in Osteoclastogenesis through Triggering Lysosome-Induced Degradation of c-Fms and RANK Surface Receptors

2020 ◽  
Vol 21 (24) ◽  
pp. 9352
Author(s):  
Manh Tien Tran ◽  
Yuka Okusha ◽  
Yunxia Feng ◽  
Masatoshi Morimatsu ◽  
Penggong Wei ◽  
...  
Keyword(s):  
Osteoclast Differentiation ◽  
Activated T Cells ◽  
Surface Receptors ◽  
Late Endosomes ◽  
Early Endosomes ◽  
D Cell ◽  
D Cells ◽  
Vitro Model

Rab11b, abundantly enriched in endocytic recycling compartments, is required for the establishment of the machinery of vesicle trafficking. Yet, no report has so far characterized the biological function of Rab11b in osteoclastogenesis. Using in vitro model of osteoclasts differentiated from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we elucidated that Rab11b served as an inhibitory regulator of osteoclast differentiation sequentially via (i) abolishing surface abundance of RANK and c-Fms receptors; and (ii) attenuating nuclear factor of activated T-cells c1 (NFATc-1) upstream signaling cascades, following RANKL stimulation. Rab11b was localized in early and late endosomes, Golgi complex, and endoplasmic reticulum; moreover, its overexpression enlarged early and late endosomes. Upon inhibition of lysosomal function by a specific blocker, chloroquine (CLQ), we comprehensively clarified a novel function of lysosomes on mediating proteolytic degradation of c-Fms and RANK surface receptors, drastically ameliorated by Rab11b overexpression in RAW-D cell-derived osteoclasts. These findings highlight the key role of Rab11b as an inhibitor of osteoclastogenesis by directing the transport of c-Fms and RANK surface receptors to lysosomes for degradation via the axis of early endosomes-late endosomes-lysosomes, thereby contributing towards the systemic equilibrium of the bone resorption phase.

Coordinate expression of secretory phospholipase A2 and cyclooxygenase-2 in activated human keratinocytes

2000 ◽  
Vol 278 (4) ◽  
pp. C822-C833 ◽  
Author(s):  
Krystyna E. Rys-Sikora ◽  
Raymond L. Konger ◽  
John W. Schoggins ◽  
Rama Malaviya ◽  
Alice P. Pentland
Keyword(s):  
Wound Repair ◽  
Human Keratinocytes ◽  
Plating Density ◽  
Coordinate Expression ◽  
Cox 2 ◽  
Type V ◽  
In Vitro Wounding

PGE2 levels are altered in human epidermis after in vivo wounding; however, mechanisms modulating PGE2 production in activated keratinocytes are unclear. In previous studies, we showed that PGE2 is a growth-promoting autacoid in human primary keratinocyte cultures, and its production is modulated by plating density, suggesting that regulated PGE2 synthesis is an important component of wound healing. Here, we examine the role of phospholipase A2(PLA2) and cyclooxygenase (COX) enzymes in modulation of PGE2 production. We report that the increased PGE2 production that occurs in keratinocytes grown in nonconfluent conditions is also observed after in vitro wounding, indicating that similar mechanisms are involved. This increase was associated with coordinate upregulation of both COX-2 and secretory PLA2 (sPLA2) proteins. Increased sPLA2 activity was also observed. By RT-PCR, we identified the presence of type IIA and type V sPLA2, along with the M-type sPLA2 receptor. Thus the coordinate expression of sPLA2 and COX-2 may be responsible for the increased prostaglandin synthesis in activated keratinocytes during wound repair.

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