Lack of alpha2-antiplasmin improves cutaneous wound healing via over-released vascular endothelial growth factor-induced angiogenesis in wound lesions

α2-Antiplasmin is associated with macrophage activation and fibrin deposition in a macrophage activation syndrome mouse model

Macrophage activation syndrome (MAS) is a life-threatening condition, characterized by cytopenia, multi-organ dysfunction, and coagulopathy associated with excessive activation of macrophages. In this study, we investigated the roles of alpha2-antiplasmin (α2AP) in the progression of MAS using fulminant MAS mouse model induced by toll-like receptor-9 agonist (CpG) and D-(+)-galactosamine hydrochloride (DG). α2AP deficiency attenuated macrophage accumulation, liver injury, and fibrin deposition in the MAS model mice. Interferon-γ (IFN-γ) is associated with macrophage activation, including migration, and plays a pivotal role in MAS progression. α2AP enhanced the IFN-γ-induced migration, and tissue factor production. Additionally, we showed that fibrin-induced macrophage activation and tumor necrosis factor-α production. Moreover, the blockade of α2AP by neutralizing antibodies attenuated macrophage accumulation, liver injury, and fibrin deposition in the MAS model mice. These data suggest that α2AP may regulate IFN-γ-induced responses and be associated with macrophage activation and fibrin deposition in the MAS progression.

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.

The uPA/uPAR System Orchestrates the Inflammatory Response, Vascular Homeostasis, and Immune System in Fibrosis Progression

Fibrotic diseases, such as systemic sclerosis (SSc), idiopathic pulmonary fibrosis, renal fibrosis and liver cirrhosis are characterized by tissue overgrowth due to excessive extracellular matrix (ECM) deposition. Fibrosis progression is caused by ECM overproduction and the inhibition of ECM degradation due to several events, including inflammation, vascular endothelial dysfunction, and immune abnormalities. Recently, it has been reported that urokinase plasminogen activator (uPA) and its receptor (uPAR), known to be fibrinolytic factors, orchestrate the inflammatory response, vascular homeostasis, and immune homeostasis system. The uPA/uPAR system may show promise as a potential therapeutic target for fibrotic diseases. This review considers the role of the uPA/uPAR system in the progression of fibrotic diseases.

Fibrinolysis Regulation: A Promising Approach to Promote Osteogenesis

Soon after bone fracture, the initiation of the coagulation cascade results in the formation of a blood clot, which acts as a natural material to facilitate cell migration and osteogenic differentiation at the fracture site. The existence of hematoma is important in early stage of bone healing, but the persistence of hematoma is considered harmful for bone regeneration. Fibrinolysis is recently regarded as a period of critical transition in angiogenic-osteogenic coupling, it thereby is vital for the complete healing of the bone. Moreover, the enhanced fibrinolysis is proposed to boost bone regeneration through promoting the formation of blood vessels, and fibrinolysis system as well as the products of fibrinolysis also play crucial roles in the bone healing process. Therefore, the purpose of this review is to elucidate the fibrinolysis-derived effects on osteogenesis and summarize the potential approaches-improving bone healing by regulating fibrinolysis, with the purpose to further understand the integral roles of fibrinolysis in bone regeneration and to provide theoretical knowledge for potential fibrinolysis-related osteogenesis strategies. Impact statement Fibrinolysis emerging as a new and viable therapeutic intervention to be contained within osteogenesis strategies, however to now, there have been no review articles which collates the information between fibrinolysis and osteogenesis. This review, therefore, focusses on the effects that fibrinolysis exerts on bone healing, with a purpose to provide theoretical reference to develop new strategies to modulate fibrinolysis to accelerate fibrinolysis thus enhancing bone healing.

Serpin-loaded extracellular vesicles promote tissue repair in a mouse model of impaired wound healing

Chronic metabolic diseases such as diabetes are characterized by delayed wound healing and a dysregulation of the inflammatory phase of wound repair. Our study focuses on changes in the payload of extracellular vesicles (EVs) communicating between immune cells and stromal cells in the wound bed, which regulate the rate of wound closure. Adoptive transfer of EVs from genetically defined mouse models are used here to demonstrate a functional and molecular basis for differences in the pro-reparative biological activity of diabetic (db/db) vs. wildtype EVs in wound healing. We identify several members of the Serpin family of serine protease inhibitors that are absent in db/db EVs, then we overexpress Serpin A1, F2 and G1 in EVs to evaluate their effect on wound healing in db/db mice. Serpins have an important role in regulating levels of elastase, plasmin and complement factors that coordinate immune cell signaling in full thickness wounds in a diabetic model. Here, we establish a novel therapeutic approach by engineering the payload of EVs based on proteomic analysis. Serpin-loaded EVs were used to rescue the Serpin deficiency identified by proteomics and promote wound healing in db/db mice, as well as evaluated how EVs affected extracellular matrix remodeling and the resolution of tissue injury. Therefore, we propose that the identification of EV payloads that are downregulated in diabetic wounds can be systematically analyzed for their functional activity and potential as a therapeutic, based on whether their re-expression in engineered EVs restores normal kinetics of tissue repair in chronic wounds.

α2-Antiplasmin as a Potential Therapeutic Target for Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin that is characterized by immune system abnormalities, vascular damage, and extensive fibrosis of the skin and visceral organs. α2-antiplasmin is known to be the main plasmin inhibitor and has various functions such as cell differentiation and cytokine production, as well as the regulation of the maintenance of the immune system, endothelial homeostasis, and extracellular matrix metabolism. The expression of α2-antiplasmin is elevated in dermal fibroblasts from systemic sclerosis patients, and the blockade of α2-antiplasmin suppresses fibrosis progression and vascular dysfunction in systemic sclerosis model mice. α2-antiplasmin may have promise as a potential therapeutic target for systemic sclerosis. This review considers the role of α2-antiplasmin in the progression of systemic sclerosis.

Alpha2-antiplasmin deficiency affects depression and anxiety-like behavior and apoptosis induced by stress in mice

OBJECTIVES

Depression is a psychiatric disorder that affects about 10% of the world's population and is accompanied by anxiety. Depression and anxiety are often caused by various stresses. However, the etiology of depression and anxiety remains unknown. It has been reported that alpha2-antiplasmin (α2AP) not only inhibits plasmin but also has various functions such as cytokine production and cell growth. This study aimed to determine the roles of α2AP on the stress-induced depression and anxiety.

METHODS

We investigated the mild repeated restraint stress-induced depressive and anxiety-like behavior in the α2AP^+/+ and α2AP^-/- mice using the social interaction test (SIT), sucrose preference test (SPT), and elevated plus maze (EPM).

RESULTS

The stresses such as the mild repeated restraint stress suppressed α2AP expression in the hippocampus of mice, and the treatment of fluoxetine (selective serotonin reuptake inhibitor [SSRI]) recovered the stress-caused α2AP suppression. We also showed that α2AP deficiency promoted the mild restraint stress-stimulated depression-like behavior such as social withdrawal and apathy and apoptosis in mice. In contrast, α2AP deficiency attenuated the mild restraint stress induced the anxiety-like behavior in mice.

CONCLUSIONS

α2AP affects the pathogenesis of depression and anxiety induced by stress.

α2-antiplasmin positively regulates endothelial-to-mesenchymal transition and fibrosis progression in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN), is microvascular complication of diabetes causes to kidney dysfunction and renal fibrosis. It is known that hyperglycemia and advanced glycation end products (AGEs) produced by hyperglycemic condition induce myofibroblast differentiation and endothelial-to-mesenchymal transition (EndoMT), and exacerbate fibrosis in DN. Recently, we demonstrated that α2-antiplasmin (α2AP) is associated with inflammatory response and fibrosis progression.

METHODS

We investigated the role of α2AP on fibrosis progression in DN using a streptozotocin-induced DN mouse model.

RESULTS

α2AP deficiency attenuated EndoMT and fibrosis progression in DN model mice. We also showed that the high glucose condition/AGEs induced α2AP production in fibroblasts (FBs), and the reduction of receptor for AGEs (RAGE) by siRNA attenuated the AGEs-induced α2AP production in FBs. Furthermore, the bloackade of α2AP by the neutralizing antibody attenuated the high glucose condition-induced pro-fibrotic changes in FBs. On the other hand, the hyperglycemic condition/AGEs induced EndoMT in vascular endothelial cells (ECs), the FBs/ECs co-culture promoted the high glucose condition-induced EndoMT compared to ECs mono-culture. Furthermore, α2AP promoted the AGEs-induced EndoMT, and the blockade of α2AP attenuated the FBs/ECs co-culture-promoted EndoMT under the high glucose condition.

CONCLUSIONS

The high glucose conditions induced α2AP production, and α2AP is associated with EndoMT and fibrosis progression in DN. These findings provide a basis for clinical strategies to improve DN.

Alpha2-Antiplasmin: The Devil You Don't Know in Cerebrovascular and Cardiovascular Disease

Alpha2-antiplasmin (α2AP), the fast-reacting, serine protease inhibitor (serpin) of plasmin, was originally thought to play a key role in protection against uncontrolled, plasmin-mediated proteolysis of coagulation factors and other molecules. However, studies of humans and mice with genetic deficiency of α2AP have expanded our understanding of this serpin, particularly in disease states. Epidemiology studies have shown an association between high α2AP levels and increased risk or poor outcome in cardiovascular diseases. Mechanistic studies in disease models indicate that α2AP stops the body's own fibrinolytic system from dissolving pathologic thrombi that cause venous thrombosis, pulmonary embolism, arterial thrombosis, and ischemic stroke. In addition, α2AP fosters the development of microvascular thrombosis and enhances matrix metalloproteinase-9 expression. Through these mechanisms and others, α2AP contributes to brain injury, hemorrhage and swelling in experimental ischemic stroke. Recent studies also show that α2AP is required for the development of stasis thrombosis by inhibiting the early activation of effective fibrinolysis. In this review, we will discuss the key role played by α2AP in controlling thrombosis and fibrinolysis and, we will consider its potential value as a therapeutic target in cardiovascular diseases and ischemic stroke.

Relation of α2-Antiplasmin Genotype and Genetic Determinants of Fibrinogen Synthesis and Fibrin Clot Formation with Vascular Endothelial Growth Factor Level in Axial Spondyloarthritis

Objective: Coagulation and fibrinolysis are interrelated with the expression of vascular endothelial growth factor (VEGF), which frequently is increased in axial spondyloarthritis (axSpA). We tested whether (i) α₂-antiplasmin (A2AP) Arg6Trp, (ii) fibrinogen, factor XIII A-subunit or B-subunit genotypes are associated with VEGF levels and assessed whether the known association between elevated VEGF and radiographic spinal progression in axSpA depends on genetic background. Methods: One hundred and eighty-six axSpA patients from the German Spondyloarthritis Inception Cohort were genotyped, characterized for VEGF levels, and statistically analyzed. The association between VEGF and radiographic spinal progression was assessed in dependence on genetic background in stratified analyses. Results: A2AP 6Trp carriage was associated with VEGF elevation (OR: 2.37, 95% CI: 1.06–5.29) and VEGF levels (6Trp, 455 ± 334 pg/mL; 6Arg/Arg, 373 ± 293 pg/mL; p < 0.008). Association between elevated VEGF and radiographic spinal progression in axSpA (OR: 3.11, 95% CI: 1.02–8.82) depended remarkably on the fibrinogen (FGA) genotype. When considering axSpA patients with elevated VEGF, in FGA rs6050A>G wild types, 42.1% of patients (8 of 19) progressed, while in G-allele carriers, no radiographic progression happened (0 of 13) (p < 0.04). Conclusions: The A2AP Arg6Trp genotype seems to influence VEGF levels in axSpA. The predictive value of VEGF elevations in respect of radiographic spinal progression in axSpA depends on FGA genotypes.

Alternatively activated macrophages are associated with the α2AP production that occurs with the development of dermal fibrosis : The role of alternatively activated macrophages on the development of fibrosis

Background

Fibrotic diseases are characterized by tissue overgrowth, hardening, and/or scarring because of the excessive production, deposition, and contraction of the extracellular matrix (ECM). However, the detailed mechanisms underlying these disorders remain unclear. It was recently reported that α2-antiplasmin (α2AP) is elevated in fibrotic tissue and that it is associated with the development of fibrosis. In the present study, we examined the mechanism underlying the production of α2AP on the development of fibrosis.

Methods

To clarify the mechanism underlying the production of α2AP on the development of fibrosis, we focused on high-mobility group box 1 (HMGB1), which is associated with the development of fibrosis. The mouse model of bleomycin-induced fibrosis was used to evaluate the production of α2AP on the development of fibrosis.

Results

We found that HMGB1 induced the production of α2AP through receptor for advanced glycation end products (RAGE) in fibroblasts. Next, we showed that macrophage reduction by a macrophage-depleting agent, clodronate, attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. We also showed that IL-4-stimulated alternatively activated macrophages induced the production of HMGB1, that IL-4-stimulated alternatively activated macrophage conditioned media (CM) induced pro-fibrotic changes and α2AP production, and that the inhibition of HMGB1 and RAGE attenuated these effects in fibroblasts. Furthermore, the blockade of IL-4 signaling by IL-4Rα neutralizing antibodies attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice.

Conclusion

These findings suggest that alternatively activated macrophage-derived HMGB1 induced the production of α2AP through RAGE and that these effects are associated with the development of fibrosis. Our findings may provide a clinical strategy for managing fibrotic disorders.

α2AP is associated with the development of lupus nephritis through the regulation of plasmin inhibition and inflammatory responses

Introduction

Lupus nephritis (LN) is a common complication of systemic lupus erythematosus (SLE), which is a chronic autoimmune disease. However, the detailed mechanisms underlying this disorder have remained unclear. Alpha2‐antiplasmin (α2AP) is known to perform various functions, such as plasmin inhibition and cytokine production, and to be associated with immune and inflammatory responses.

Methods

We investigated the roles of α2AP in the pathogenesis of LN using a pristane‐induced lupus mouse model.

Results

The levels of plasmin‐α2AP complex and α2AP were elevated in the lupus model mice. In addition, α2AP deficiency attenuated the pristane‐induced glomerular cell proliferation, mesangial matrix expansion, collagen production, fibrin deposition, immunoglobulin G deposition, and proinflammatory cytokine production in the model mice. We also showed that interferon‐γ (IFN‐γ), which is an essential inducer of LN, induced α2AP production through the c‐Jun N‐terminal kinase (JNK) pathway in fibroblasts. In addition, plasmin attenuated the IFN‐γ‐induced proinflammatory cytokine production through the AMPK pathway in macrophages, and α2AP eliminated these effects. Furthermore, we showed that α2AP induced proinflammatory cytokine production through the ERK1/2 and JNK pathways in macrophages.

Conclusion

α2AP regulates the inflammatory responses through plasmin inhibition and proinflammatory cytokine production and is associated with the development of LN. Our findings may be used to develop a novel therapeutic approach for SLE.

The Role of Fibrinolytic Regulators in Vascular Dysfunction of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by vascular dysfunction and extensive fibrosis of the skin and visceral organs. Vascular dysfunction is caused by endothelial cell (EC) apoptosis, defective angiogenesis, defective vasculogenesis, endothelial-to-mesenchymal transition (EndoMT), and coagulation abnormalities, and exacerbates the disease. Fibrinolytic regulators, such as plasminogen (Plg), plasmin, α2-antiplasmin (α2AP), tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plasminogen activator inhibitor 1 (PAI-1), and angiostatin, are considered to play an important role in the maintenance of endothelial homeostasis, and are associated with the endothelial dysfunction of SSc. This review considers the roles of fibrinolytic factors in vascular dysfunction of SSc.

Novel preclinical murine model of trauma-induced elbow stiffness

BACKGROUND

Peri-articular injury may result in functional deficits and pain. In particular, post-traumatic elbow stiffness is a debilitating condition, precluding patients from performing activities of daily living. As such, clinicians and basic scientists alike, aim to develop novel therapeutic interventions to prevent and treat elbow stiffness; thereby reducing patient morbidity. Yet, there is a paucity of pre-clinical models of peri-articular stiffness, especially of the upper extremity, necessary to develop and test the efficacy of therapeutics. We set out to develop a pre-clinical murine model of elbow stiffness, resulting from soft tissue injury, with features characteristic of pathology observed in these patients.

METHODS

A soft tissue peri-elbow injury was inflicted in mice using cardiotoxin. Pathologic tissue repair was induced by creating an investigator-imposed deficiency of plasminogen, a protease essential for musculoskeletal tissue repair. Functional testing was conducted through analysis of grip strength and gait. Radiography, microcomputed tomography, and histological analyses were employed to quantify development of heterotopic ossification.

RESULTS

Animals with peri-elbow soft tissues injury in conjunction with an investigator-imposed plasminogen deficiency, developed a significant loss of elbow function measured by grip strength (2.387 ± 0.136 N vs 1.921 ± 0.157 N, ****, p < 0.0001) and gait analysis (35.05 ± 2.775 mm vs 29.87 ± 2.075 mm, ***, p < 0.0002). Additionally, plasminogen deficient animals developed capsule thickening, delayed skeletal muscle repair, fibrosis, chronic inflammation, and heterotopic ossification; all features characteristic of pathology observed in patients with trauma-induced elbow stiffness.

CONCLUSION

A soft tissue injury to the peri-elbow soft tissue with a concomitant deficiency in plasminogen, instigates elbow stiffness and pathologic features similar to those observed in humans. This pre-clinical model is valuable for translational studies designed to investigate the contributions of pathologic features to elbow stiffness or as a high-throughput model for testing therapeutic strategies designed to prevent and treat trauma-induced elbow stiffness.

α2-antiplasmin modulates bone formation by negatively regulating osteoblast differentiation and function

α2-antiplasmin (α2AP) is known to be a physiological inhibitor of plasmin. Previously, we showed that α2AP displays various functions, such as promotion of extracellular matrix production, cell growth, and cell differentiation that are not promoted by its function as a plasmin inhibitor. We herein investigated the role of α2AP in bone formation by examining calcein incorporation after its injection in α2AP-deficient mice. We found that α2AP deficiency enhanced the bone formation rate in mice. We also found that the osteocalcin expression and alkaline phosphatase activity were elevated in the femur and serum of the α2AP-deficient mice. Intriguingly, α2AP deficiency promoted osteoblast (OB) differentiation of primary calvarial OBs. In contrast, α2AP attenuated OB differentiation of mouse osteoblastic the MC3T3-E1 cells. Furthermore, α2AP attenuated Wnt-3a-induced β-catenin expression and low‑density lipoprotein receptor-related protein 6 activation in the MC3T3-E1 cells. These results suggest that α2AP negatively affects OB differentiation and function by inhibiting the Wnt/β-catenin pathway. These findings provide a basis for clinical strategies to improve various bone disorders.

α2AP regulates vascular alteration by inhibiting VEGF signaling in systemic sclerosis: the roles of α2AP in vascular dysfunction in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissues disease of unknown origin characterized by vascular damage and extensive fibrosis. Recently, we demonstrated that α2-antiplasmin (α2AP) is associated with the development of fibrosis in SSc. We herein investigate the roles of α2AP in vascular dysfunction in SSc.

METHODS

Vascular damage in mice was determined by the levels of blood vessels and blood flow. Vascular functions in vascular endothelial cells (ECs) were determined by the levels of tube formation, cell proliferation, and endothelial junction-associated protein (VE-cadherin and PECAM1) production.

RESULTS

The administration of α2AP induced vascular damage in mice. Conversely, the α2AP neutralization improved vascular damage in a bleomycin-induced mouse model of SSc. Additionally, we showed that the SSc fibroblast-conditioned media induced the reduction of tube formation, cell proliferation, and endothelial junction-associated protein production in ECs, and that α2AP neutralization improved them. We also examined the mechanisms underlying the effects of α2AP on vascular alteration in SSc and found that α2AP attenuated vascular endothelial growth factor-induced tube formation, cell proliferation, and endothelial junction-associated protein production through the adipose triglyceride lipase/tyrosine phosphatase SHP2 axis in ECs.

CONCLUSION

Our findings demonstrate that α2AP is associated with vascular alteration, and that the blocking of α2AP improves vascular dysfunction in SSc.

Plasmin Prevents Dystrophic Calcification After Muscle Injury

Extensive or persistent calcium phosphate deposition within soft tissues after severe traumatic injury or major orthopedic surgery can result in pain and loss of joint function. The pathophysiology of soft tissue calcification, including dystrophic calcification and heterotopic ossification (HO), is poorly understood; consequently, current treatments are suboptimal. Here, we show that plasmin protease activity prevents dystrophic calcification within injured skeletal muscle independent of its canonical fibrinolytic function. After muscle injury, dystrophic calcifications either can be resorbed during the process of tissue healing, persist, or become organized into mature bone (HO). Without sufficient plasmin activity, dystrophic calcifications persist after muscle injury and are sufficient to induce HO. Downregulating the primary inhibitor of plasmin (α2-antiplasmin) or treating with pyrophosphate analogues prevents dystrophic calcification and subsequent HO in vivo. Because plasmin also supports bone homeostasis and fracture repair, increasing plasmin activity represents the first pharmacologic strategy to prevent soft tissue calcification without adversely affecting systemic bone physiology or concurrent muscle and bone regeneration. © 2016 American Society for Bone and Mineral Research.

Role of heparin and non heparin binding serpins in coagulation and angiogenesis: A complex interplay

Pro-coagulant, anti-coagulant and fibrinolytic pathways are responsible for maintaining hemostatic balance under physiological conditions. Any deviation from these pathways would result in hypercoagulability leading to life threatening diseases like myocardial infarction, stroke, portal vein thrombosis, deep vein thrombosis (DVT) and pulmonary embolism (PE). Angiogenesis is the process of sprouting of new blood vessels from pre-existing ones and plays a critical role in vascular repair, diabetic retinopathy, chronic inflammation and cancer progression. Serpins; a superfamily of protease inhibitors, play a key role in regulating both angiogenesis and coagulation. They are characterized by the presence of highly conserved secondary structure comprising of 3 β-sheets and 7-9 α-helices. Inhibitory role of serpins is modulated by binding to cofactors, specially heparin and heparan sulfate proteoglycans (HSPGs) present on cell surfaces and extracellular matrix. Heparin and HSPGs are the mainstay of anti-coagulant therapy and also have therapeutic potential as anti-angiogenic inhibitors. Many of the heparin binding serpins that regulate coagulation cascade are also potent inhibitors of angiogenesis. Understanding the molecular mechanism of the switch between their specific anti-coagulant and anti-angiogenic role during inflammation, stress and regular hemostasis is important. In this review, we have tried to integrate the role of different serpins, their interaction with cofactors and their interplay in regulating coagulation and angiogenesis.

The Antifibrotic Effect of α2AP Neutralization in Systemic Sclerosis Dermal Fibroblasts and Mouse Models of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by the fibrosis of skin and visceral organs, and peripheral circulatory disturbance. We recently demonstrated that α2-antiplasmin (α2AP), which is the physiological inhibitor of plasmin, is associated with the development of fibrosis. The aim of this study was to clarify the role of α2AP in the pathogenesis of SSc. The administration of α2AP in mice induced profibrotic changes, such as increased dermal thickness, collagen production, and myofibroblast differentiation. Conversely, the α2AP neutralization prevented not only profibrotic changes, but also the production of autoantibodies in bleomycin-induced mouse models of SSc. The expression of α2AP was elevated in dermal fibroblasts obtained from patients with SSc. Furthermore, α2AP treatment promoted profibrotic changes in human normal dermal fibroblasts, and α2AP neutralization reversed a profibrotic phenotype of SSc dermal fibroblasts, in the absence of plasmin. Our findings demonstrated that α2AP has a profibrotic effect probably not by the action as a plasmin inhibitor, and that the blocking of α2AP exerts an antifibrotic effect in humans and mice with SSc.

α₂-Antiplasmin is involved in bone loss induced by ovariectomy in mice

The mechanism of postmenopausal osteoporosis is not fully understood. α2-Antiplasmin (α2-AP) is the primary inhibitor of plasmin in the fibrinolytic system, but is known to have activities beyond fibrinolysis. However, its role in bone metabolism and the pathogenesis of osteoporosis remains unknown. In the current study, we therefore examined the effects of α2-AP deficiency on ovariectomy (OVX)-induced bone loss by using wild-type and α2-AP-deficient mice. Quantitative computed tomography analysis revealed that α2-AP deficiency blunted OVX-induced trabecular bone loss in mice. Moreover, α2-AP deficiency significantly blunted serum levels of bone-specific alkaline phosphatase, cross-linked C-telopeptide of type I collagen, and interleukin (IL)-1β elevated by OVX. α2-AP treatment elevated the levels of IL-1β and tumor necrosis factor (TNF)-α mRNA in RAW 264.7 cells, although it suppressed osteoclast formation induced by receptor activator of nuclear factor-κB ligand. α2-AP treatment activated ERK1/2 and p38 MAP kinase pathways in RAW 264.7 cells, and these MAP kinase inhibitors antagonized the levels of IL-1β mRNA elevated by α2-AP. The data demonstrate that α2-AP is linked to bone loss due to OVX, through a mechanism that depends in part on the production of IL-1β and TNF-α in monocytes.

Topical Single-dose Vascular Endothelial Growth Factor has No Effect on Soft Tissue Healing

Background:

Vascular endothelial growth factor (VEGF) production in dermal wounds has been evaluated for evidence that it plays a probable role in wound healing. Events such as increased vascular permeability and concentration of inflammatory cells on the site of injury, produced by VEGF, were linked to tissue repair.

Aim:

The present study aimed to evaluate the effects of single-dose topical administration of VEGF on wound healing.

Materials and Methods:

A total of 30 male Wistar albino rats weighing 250-280 g were used in this study. In addition, 2-cm-long skin incisions were created over bilaterally exposed skin of the tibia region in each rat. VEGF plasmid 2 μg was administered locally into the right side wound bed of each animal. No other procedure besides skin closure was administered on the left side. To determine histologic assessments, skin samples were obtained from six anesthetized rats at each interval (4, 8, 12, 16 and 30 days) through excisional biopsy. The tissues were fixed in 10% neutral-buffered formalin for 1 week and then embedded in paraffin wax. Transverse sections of the embedded tissue 5-7 μm thick were stained with hematoxylin and eosin (H and E).

Results:

There was no significant difference regarding necrosis, epithelialization, inflammation, fibroblast activity, ulcerative formation, or hemorrhage between experimental and control groups. No statistically significant difference was found between the groups regarding granulation tissue formation and epidermal thickness.

Conclusion:

The administration method and dosage of VEGF is a major factor in terms of its effectiveness. The results of the present study did not evaluate the effectiveness of single-dose 2 μg topical administration of VEGF; however, various doses of VEGF plasmid should be tested in future studies in order to provide beneficial effects from topical administration of VEGF.

α2AP mediated myofibroblast formation and the development of renal fibrosis in unilateral ureteral obstruction

Renal fibrosis is the final common pathway of a wide variety of chronic kidney diseases. Myofibroblast formation via the differentiation of from tissue-resident fibroblasts and bone marrow-derived mesenchymal stem cells (MSCs), and epithelial-to-mesenchymal transition (EMT) is known to play a pivotal role in the development of renal fibrosis. However, the detailed mechanisms underlying this disorder remain unclear. We herein investigated the role of alpha 2-antiplasmin (α2AP) in myofibroblast formation and the development of renal fibrosis. We observed the development of renal fibrosis using unilateral ureteral obstruction (UUO). α2AP had accumulated in the UUO-induced obstructed kidneys and α2AP deficiency attenuated UUO-induced renal fibrosis in mice. The degree of myofibroblast formation in the obstructed kidneys of α2AP(-/-) mice was less than that in α2AP(+/+) mice. In vitro, α2AP induced myofibroblast formation in renal tubular epithelial cells (RTECs), renal fibrosblasts, and bone marrow-derived mesenchymal stem cells (MSCs). α2AP also induced the production of TGF-β, which is known to be a key regulator of myofibroblast formation and fibrosis. α2AP-induced the TGF-β production was significantly reduced by SP600125, c-Jun N-terminal kinase (JNK) specific inhibitor. Our findings suggest that α2AP induces myofibroblast formation in the obstructed kidneys, and mediates the development of renal fibrosis.

The epidermal growth factor-like domain of CD93 is a potent angiogenic factor

Human CD93, an epidermal growth factor (EGF)-like domain containing transmembrane protein, is predominantly expressed in the vascular endothelium. Studies have shown that AA4, the homolog of CD93 in mice, may mediate cell migration and angiogenesis in endothelial cells. Soluble CD93 has been detected in the plasma of healthy individuals. However, the role of soluble CD93 in the endothelium remains unclear. Recombinant soluble CD93 proteins with EGF-like domains (rCD93D123, with domains 1, 2, and 3; and rCD93D23, with domains 2 and 3) were generated to determine their functions in angiogenesis. We found that rCD93D23 was more potent than rCD93D123 in stimulating the proliferation and migration of human umbilical vein endothelial cells (HUVECs). Production of matrix-metalloproteinase 2 increased after the HUVECs were treated with rCD93D23. Further, in a tube formation assay, rCD93D23 induced cell differentiation of HUVECs through phosphoinositide 3-kinase/Akt/endothelial nitric oxide synthase and extracellular signal-regulated kinases-1/2 signaling. Moreover, rCD93D23 promoted blood vessel formation in a Matrigel-plug assay and an oxygen-induced retinopathy model in vivo. Our findings suggest that the soluble EGF-like domain containing CD93 protein is a novel angiogenic factor acting on the endothelium.

Plasminogen/plasmin modulates bone metabolism by regulating the osteoblast and osteoclast function

The contribution of plasminogen (Plg)/plasmin, which have claimed to be the main fibrinolytic regulators in the bone metabolism, remains unclear. This study evaluated how the absence of Plg affects the function of osteoblast (OB) and osteoclast (OC). There was a larger population of pre-OCs in bone marrow-derived cells from the Plg(-/-) mice than the population of that from the WT mice. In addition, the absence of Plg suppressed the expression of osteoprotegerin in OBs. Moreover, an exogenous plasmin clearly induced the osteoprotegerin expression in Plg(-/-) OBs. The osteoclastogenesis of RAW264.7 mouse monocyte/macrophage lineage cells in co-culture with OBs from the Plg(-/-) mice was significantly accelerated in comparison with that in co-culture with OBs from the WT mice. Intriguingly, the accelerated OC differentiation of RAW264.7 cells co-cultured with Plg(-/-) OBs was clearly suppressed by the treatment of an exogenous plasmin. Consequently, Plg(-/-) mice display decreased bone mineral density. These findings could eventually lead to the development of new clinical therapies for bone disease caused by a disorder of the fibrinolytic system.

alpha2-antiplasmin is associated with the progression of fibrosis

Systemic sclerosis results in tissue fibrosis due to the activation of fibroblasts and the ensuing overproduction of the extracellular matrix. We previously reported that the absence of alpha2-antiplasmin (alpha2AP) attenuated the process of dermal fibrosis; however, the detailed mechanism of how alpha2AP affects the progression of fibrosis remained unclear. The goal of the present study was to examine the role of alpha2AP in fibrotic change. We observed significantly higher levels of alpha2AP expression in the skin of bleomycin-injected systemic sclerosis model mice in comparison with the levels seen in control mice. We also demonstrated that alpha2AP induced myofibroblast differentiation, and the absence of alpha2AP attenuated the induction of myofibroblast differentiation. Moreover, we found that connective tissue growth factor induced the expression of alpha2AP through both the extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) pathways in fibroblasts. Interestingly, alpha2AP also induced transforming growth factor-beta expression through the same pathways, and the inhibition of ERK1/2 and JNK slowed the progression of bleomycin-induced fibrosis. Our findings suggest that alpha2AP is associated with the progression of fibrosis, and regulation of alpha2AP expression by the ERK1/2 and JNK pathways may be an effective antifibrotic therapy for the treatment of systemic sclerosis.

Alpha2-antiplasmin is involved in the production of transforming growth factor beta1 and fibrosis

BACKGROUND

Fibrotic disease occurs in most tissues. Transforming growth factor (TGF)-beta is the major inducer of fibrosis. The fibrinolytic system is considered to play an important role in the degradation of extracellular matrices. However, the detailed mechanism of how this system affects fibrosis remains unclear.

METHODS AND RESULTS

We examined experimental fibrosis in mice with a deficiency of alpha(2)-antiplasmin (alpha2AP), which is a potent and specific plasmin inhibitor. We found that the lack of alpha2AP attenuated bleomycin-induced TGF-beta(1) synthesis and fibrosis. In addition, the production of TGF-beta(1) from the explanted fibroblasts of alpha2AP(-/-) mice decreased dramatically as compared to that in wild-type mice. Moreover, we found that alpha2AP specifically induces the production of TGF-beta(1) in fibroblasts.

CONCLUSION

The lack of alpha2AP attenuated TGF-beta(1) synthesis, thereby resulting in attenuated fibrosis. This is the first report to describe the crucial role that alpha2AP plays in TGF-beta(1) synthesis during the process of fibrosis. Our results provide new insights into the role of alpha2AP in fibrosis.

Soft tissue wounds and principles of healing

Wound healing is a complex interchange, orchestrated between cellular components that play their respective parts signaled by and mediated by different cellular instruments of healing. When healing is performed well, the final product is a thing of beauty. When healing is delayed, interrupted, or excessive, then unsightly scars of chronic painful wounds that are frustrating to the patient and physician occur.