Plasminogen is a master regulator and a potential drug candidate for the healing of radiation wounds

Topical Application of Autologous Plasma-Derived Plasminogen Accelerates Healing of Chronic Foot Ulcers in Type 2 Diabetes Patients

Plasminogen (Pg) is currently considered a master regulator of wound healing, but the molecular mechanisms of its efficacy in improving impaired closure of chronic skin ulcers in type 2 diabetes patients remain unclear. Here, we investigated wound healing effects of autologous plasma-derived Pg in diabetes patients with chronic foot ulcers and evaluated Pg-induced changes in levels of key protein markers related to wound repair. Type 2 diabetes patients with chronic wounds of lower extremities were included in the study and received topical applications of Pg in a dose of 1.0 mg/mL every 2 days during 20 days, in addition to the standard wound management treatment. Patients treated only according to conventional protocol served as a control. Wound closure rates were monitored by digital planimetry of wound areas. Plasminogen supplementary treatment significantly accelerated relative wound closure as compared with diabetes patients from the control group (24 ± 4 days vs 120 ± 17 days, respectively, P < .01). As shown by Western blot, Pg application reduced expression of protein regulators of hypoxia events, angiogenesis, and autophagy such as hypoxia-inducible factor-1α (by 6.3-folds, P < .01), angiostatins (by 2.5-folds, P < .05), and autophagy marker LC3-II/LC3-I (by 8.6-folds, P < .05), while increasing vascular endothelial growth factor level by 1.9-folds (P < .05). Gelatin zymography showed that Pg-supplemented therapy decreased activity of matrix metalloproteinase-9 (MMP-9) by 3.5-folds at the end of treatment period (P < .01). We report here for the first time that topically applied plasma-derived Pg has a pronounced beneficial effect in promoting foot ulcer healing in patients with type 2 diabetes through preventing hypoxia-induced signaling, reducing autophagy flux, diminishing excessive MMP activity, and enhancing angiogenesis.

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.

Harnessing strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns

Diabetic wound is a great threat to patient's health and lives. The refractory diabetic wound shows spatial inflammation patterns, in which the early-wound pattern depicts a deprived acute inflammatory response, and the long-term non-healing wound pattern delineates an excessive and persistent inflammation due to the delayed immune cell infiltration in a positive feedback loop. In this work, we give points to some strategies to normalize the dysregulated immune process based on the spatial inflammation pattern differences in diabetic wound healing. First of all, inhibiting inflammatory response to avoid subsequent persistent and excessive immune infiltration for the early diabetic wound is proposed. However, diabetic wounds are unperceptive trauma that makes patients miss the best treatment time. Therefore, we also introduce two strategies for the long-term non-healing diabetic wound. One strategy is about changing chronic wounds to acute ones, which aims to rejuvenate M1 macrophages in diabetic wounds and make spontaneous M2 polarization possible. To activate the controllable proinflammatory response, western medicine delivers proinflammatory molecules while traditional Chinese medicine develops "wound-pus promoting granulation tissue growth theory". Another strategy to solve long-term non-healing wounds is seeking switches that target M1/M2 transition directly. These investigations draw a map that delineates strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns systematically.

Crosstalk between the plasminogen/plasmin system and inflammation resolution

The plasminogen/plasmin (Plg/Pla) system, best known for its classical role in thrombolysis, has been recently highlighted as a regulator of other biological processes in mammals, including key steps involved in the resolution of inflammation. Inflammation resolution is a complex process coordinated by different cellular effectors, notably leukocytes, and active mediators, and is initiated shortly after the inflammatory response begins. Once the inflammatory insult is eliminated, an effective and timely engagement of proresolution programs prevents persistent inflammation, thereby avoiding excessive tissue damage, fibrosis, and the development of autoimmunity. Interestingly, recent studies demonstrate that Plg/Pla and their receptor, plasminogen receptor KT (Plg-RKT), regulate key steps in inflammation resolution. The number of studies investigating the involvement of the Plg/Pla system in these and other aspects of inflammation, including degradation of extracellular matrices, immune cell migration, wound healing, and skeletal growth and maintenance, highlights key roles of the Plg/Pla system during physiological and pathologic conditions. Here, we discuss robust evidence in the literature for the emerging roles of the Plg/Pla system in key steps of inflammation resolution. These findings suggest that dysregulation in Plg production and its activation plays a role in the pathogenesis of inflammatory diseases. Elucidating central mechanisms underlying the role of Plg/Pla in key steps of inflammation resolution either in preclinical models of inflammation or in human inflammatory conditions, can provide a rationale for the development of new pharmacologic interventions to promote resolution of inflammation, and open new pathways for the treatment of thromboinflammatory conditions.

Tranexamic acid for haemostasis and beyond: does dose matter?

Tranexamic acid (TXA) is a widely used antifibrinolytic agent that has been used since the 1960's to reduce blood loss in various conditions. TXA is a lysine analogue that competes for the lysine binding sites in plasminogen and tissue-type plasminogen activator impairing its interaction with the exposed lysine residues on the fibrin surface. The presence of TXA therefore, impairs the plasminogen and tPA engagement and subsequent plasmin generation on the fibrin surface, protecting fibrin clot from proteolytic degradation. However, critical lysine binding sites for plasmin(ogen) also exist on other proteins and on various cell-surface receptors allowing plasmin to exert potent effects on other targets that are unrelated to classical fibrinolysis, notably in relation to immunity and inflammation. Indeed, TXA was reported to significantly reduce post-surgical infection rates in patients after cardiac surgery unrelated to its haemostatic effects. This has provided an impetus to consider TXA in other indications beyond inhibition of fibrinolysis. While there is extensive literature on the optimal dosage of TXA to reduce bleeding rates and transfusion needs, it remains to be determined if these dosages also apply to blocking the non-canonical effects of plasmin.

Antibody gene transfer treatment drastically improves epidermal pathology in a keratitis ichthyosis deafness syndrome model using male mice

BACKGROUND

Keratitis ichthyosis deafness (KID) syndrome is a rare disorder caused by hemichannel (HC) activating gain-of-function mutations in the GJB2 gene encoding connexin (Cx) 26, for which there is no cure, or current treatments based upon the mechanism of disease causation.

METHODS

We applied Adeno Associated Virus (AAV) mediated mAb gene transfer (AAVmAb) to treat the epidermal features of KID syndrome with a well-characterized HC blocking antibody using male mice of a murine model that replicates the skin pathology of the human disease.

FINDINGS

We demonstrate that in vivo AAVmAb treatment significantly reduced the size and thickness of KID lesions, in addition to blocking activity of mutant HCs in the epidermis in vivo. We also show that AAVmAb treatment eliminated abnormal keratinocyte proliferation and enlarged cell size, decreased apoptosis, and restored the normal distribution of keratin expression.

INTERPRETATION

Our findings reinforce the critical role played by increased HC activity in the skin pathology associated with KID syndrome. They also underscore the clinical potential of anti-HC mAbs coupled with genetic based delivery systems for treating the underlying mechanistic basis of this disorder. Inhibition of HC activity is an ideal therapeutic target in KID syndrome, and the genetic delivery of mAbs targeted against mutant HCs could form the basis of new therapeutic interventions to treat this incurable disease.

FUNDING

Fondazione Telethon grant GGP19148 and University of Padova grant Prot. BIRD187130 to FM; Foundation for Ichthyosis and Related Skin Types (FIRST) and National Institutes of Health grant EY 026911 to TWW.

An older diabetes-induced mice model for studying skin wound healing

Advances in wound treatment depend on the availability of animal models that reflect key aspects of human wound healing physiology. To this date, the accepted mouse models do not reflect defects in the healing process for chronic wounds that are associated with type two diabetic skin ulcers. The long term, systemic physiologic stress that occurs in middle aged or older Type 2 diabetes patients is difficult to simulate in preclinical animal model. We have strived to incorporate the essential elements of this stress in a manageable mouse model: long term metabolic stress from obesity to include the effects of middle age and thereafter onset of diabetes. At six-weeks age, male C57BL/6 mice were separated into groups fed a chow and High-Fat Diet for 0.5, 3, and 6 months. Treatment groups included long term, obesity stressed mice with induction of diabetes by streptozotocin at 5 months, and further physiologic evaluation at 8 months old. We show that this model results in a severe metabolic phenotype with insulin resistance and glucose intolerance associated with obesity and, more importantly, skin changes. The phenotype of this older age mouse model included a transcriptional signature of gene expression in skin that overlapped that observed with elderly patients who develop diabetic foot ulcers. We believe this unique old age phenotype contrasts with current mice models with induced diabetes.

Dual viscosity mixture vehicle for intratympanic steroid treatment modifies the ROS and inflammation related proteomes

Until recently, the most standard treatment for sensorineural or sudden hearing loss, which is caused by inner ear damage or deterioration, has been systemic oral steroid administration. In recent, intratympanic steroid injections such as dexamethasone have been used for the treatment of sudden hearing loss as well. It is injected into the tympanic cavity through its membrane and is expected to diffuse over the round window located between the tympanic cavity and the inner ear. However, in clinical situations, the delivery time of steroids to the inner ear is shorter than 24 h, which does not allow for a sufficient therapeutic effect. Therefore, we applied a previously invented dual viscosity mixture vehicle (DVV) for intratympanic dexamethasone to a guinea pig model, which could reduce the side effects of systemic steroid administration with sufficient dwelling time for the treatment of hearing loss, and we investigated the physiological changes with a global proteomic approach. In this study, we extracted perilymph in three different conditions from guinea pigs treated with dexamethasone-embedded DVV, dexamethasone mixed in saline, and control groups to compare proteomic changes using tandem mass spectrometry analysis. After liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) analysis, we first identified 46 differentially expressed proteins (DEPs) that were statistically significant after one-way ANOVA multiple-sample test. We also performed pairwise comparisons among each group to identify DEPs closely related to the treatment response of dexamethasone-embedded DVV. Gene ontology enrichment analysis showed that these DEPs were mostly related to inflammation, immune, actin remodeling, and antioxidant-related processes. As a result, the proteome changes in the DVV-treated groups revealed that most upregulated proteins activate the cell proliferation process, and downregulated proteins inhibit apoptosis and inflammatory reactions. Moreover, the reactive oxygen process was also regulated by DEPs after DVV treatment.

Harnessing the Natural Healing Power of Colostrum: Bovine Milk-Derived Extracellular Vesicles from Colostrum Facilitating the Transition from Inflammation to Tissue Regeneration for Accelerating Cutaneous Wound Healing

As wound healing is an extremely complicated process, consisting of a cascade of interlocking biological events, successful wound healing requires a multifaceted approach to support appropriate and rapid transitions from the inflammatory to proliferative and remodeling phases. In this regard, here the potential use of bovine milk extracellular vesicles (EVs) to enhance wound healing is investigated. The results show that milk EVs promote fibroblast proliferation, migration, and endothelial tube formation. In particular, milk EVs derived from colostrum (Colos EVs) contain various anti-inflammatory factors facilitating the transition from inflammation to proliferation phase, as well as factors for tissue remodeling and angiogenesis. In an excisional wound mouse model, Colos EVs promote re-epithelialization, activate angiogenesis, and enhance extracellular matrix maturation. Interestingly, Colos EVs are further found to be quite resistant to freeze-drying procedures, maintaining their original characteristics and efficacy for wound repair after lyophilization. These findings on the superior stability and excellent activity of milk Colos EVs indicate that they hold great promise to be developed as anti-inflammatory therapeutics, especially for the treatment of cutaneous wounds.

Clinical factors affecting the determination of radiotherapy-induced skin toxicity in breast cancer

Purpose

Radiotherapy is essential for the treatment of breast cancer (BC). However, adverse effects may occur in healthy tissue, during treatment and even after several months. Although it is known that this clinical radiosensitivity is multifactorial, the factors involved are unknown yet. In this study, we evaluated the effect of these factors on the development of radiodermatitis in patients undergoing radiotherapy.

Materials and Methods

Demographic and lifestyle data collected during face-to-face interviews of 122 BC patients and data from clinical records were investigated. Most patients underwent conventional three-dimensional radiotherapy treatment. A total dose of 50 Gy was administered (2 Gy/day), followed by a boost in a tumor bed with a total dose of 18 Gy (2 Gy/day). Radiotoxicity was evaluated weekly using the Radiation Therapy Oncology Group classification system (range, 0 to 4, according to the severity).

Results

In the present study, 75.4% of patients presented acute skin toxic effects with different degrees of severity. In 25% of cases, these effects manifested at the end of the fourth week at a cumulative dose of 40 Gy. The association of grade ≥2 acute skin reactions with body mass index (BMI) and breast size and between grade 3–4 and age was positive compared with controls. However, the role of the other factors could not be confirmed.

Conclusion

Analysis of the factors related to individual radiosensitivity suggests that age, BMI and breast size play an important role in the development of acute skin toxicity during treatment. Particular attention to patients who present these characteristics would help to control treatment effectiveness and therefore optimize their quality of life.

Plasminogen: an enigmatic zymogen

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. To date, therapeutic targeting of the fibrinolytic system has been for 2 purposes: to promote plasmin generation for thromboembolic conditions or to stop plasmin to reduce bleeding. However, plasmin and plasminogen serve other important functions, some of which are unrelated to fibrin removal. Indeed, for >40 years, the antifibrinolytic 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 behavior and further influence immune and inflammatory processes. Plasminogen administration itself has been reported to improve thrombolysis and to accelerate wound repair. Although many of these more recent findings have been derived from in vitro or animal studies, the use of antifibrinolytic agents to reduce bleeding in humans has revealed additional clinically relevant consequences, particularly in relation to reducing infection risk that is independent of its hemostatic effects. The finding that many viruses harness the host plasminogen to aid infectivity has suggested that antifibrinolytic agents may have antiviral 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 hemostasis.

Plasmin, Immunity, and Surgical Site Infection

SSI are a universal economic burden and increase individual patient morbidity and mortality. While antibiotic prophylaxis is the primary preventative intervention, these agents are not themselves benign and may be less effective in the context of emerging antibiotic resistant organisms. Exploration of novel therapies as an adjunct to antimicrobials is warranted. Plasmin and the plasminogen activating system has a complex role in immune function. The immunothrombotic role of plasmin is densely interwoven with the coagulation system and has a multitude of effects on the immune system constituents, which may not always be beneficial. Tranexamic acid is an antifibrinolytic agent which inhibits the conversion of plasminogen to plasmin. Clinical trials have demonstrated a reduction in surgical site infection in TXA exposed patients, however the mechanism and magnitude of this benefit is incompletely understood. This effect may be through the reduction of local wound haematoma, decreased allogenic blood transfusion or a direct immunomodulatory effect. Large scale randomised clinical trial are currently being undertaken to better explain this association. Importantly, TXA is a safe and widely available pharmacological agent which may have a role in the reduction of SSI.

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.

Repurposing of Plasminogen: An Orphan Medicinal Product Suitable for SARS-CoV-2 Inhalable Therapeutics

The SARS-CoV-2 infection is associated with pulmonary coagulopathy, which determines the deposition of fibrin in the air spaces and lung parenchyma. The resulting lung lesions compromise patient pulmonary function and increase mortality, or end in permanent lung damage for those who have recovered from the COVID-19 disease. Therefore, local pulmonary fibrinolysis can be efficacious in degrading pre-existing fibrin clots and reducing the conversion of lung lesions into lasting scars. Plasminogen is considered a key player in fibrinolysis processes, and in view of a bench-to-bedside translation, we focused on the aerosolization of an orphan medicinal product (OMP) for ligneous conjunctivitis: human plasminogen (PLG-OMP) eye drops. As such, the sterile and preservative-free solution guarantees the pharmaceutical quality of GMP production and meets the Ph. Eur. requirements of liquid preparations for nebulization. PLG-OMP aerosolization was evaluated both from technological and stability viewpoints, after being submitted to either jet or ultrasonic nebulization. Jet nebulization resulted in a more efficient delivery of an aerosol suitable for pulmonary deposition. The biochemical investigation highlighted substantial protein integrity maintenance with the percentage of native plasminogen band > 90%, in accordance with the quality specifications of PLG-OMP. In a coherent way, the specific activity of plasminogen is maintained within the range 4.8–5.6 IU/mg (PLG-OMP pre-nebulization: 5.0 IU/mg). This is the first study that focuses on the technological and biochemical aspects of aerosolized plasminogen, which could affect both treatment efficacy and clinical dosage delivery. Increasing evidence for the need of local fibrinolytic therapy could merge with the availability of PLG-OMP as an easy handling solution, readily aerosolizable for a fast translation into an extended clinical efficacy assessment in COVID-19 patients.