Tag Archives: angiostatins
Circulating levels of potential markers of ischemic stroke in patients with the different forms of atrial fibrillation and chronic heart failure
A. O. Tykhomyrov1*, O. Yu. Sirenko2, O. V. Kuryata2
1Department of Enzyme Chemistry and Biochemistry,
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine;
2Department of Internal Medicine 2, Phthisiology,
Occupational Diseases and Clinical Immunology, Dnipro State Medical University, Dnipro, Ukraine;
*e-mail: artem_tykhomyrov@ukr.net
Received: 19 January 2024; Revised: 13 March 2024;
Accepted: 17 March 2024; Available on-line: 30 April 2024
Atrial fibrillation (AF) is the most common abnormal type of heart rhythm (cardiac arrhythmia), which is considered the leading cause of stroke. There have been limited studies on the prognostic markers for atrial disease and AF-associated ischemic stroke, despite the high demand for this procedure in daily clinical practice to monitor disease course and assess risk of stroke in patients with AF and chronic heart failure (CHF). Thus, the aim of the present study was to evaluate the levels of serum biomarkers related to ischemic stroke in CHF patients with the different forms of AF. Forty-six patients with various types of AF (paroxysmal, persistent and permanent) with or without ischemic stroke were enrolled in the study, 36 clinically healthy donors served as a control. The levels of inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF) and angiostatins (AS) were evaluated by western blot analysis in the serum. The levels of active matrix metalloproteinases (MMPs) were analysed by gelatin zymography. Elevated levels of iNOS were shown in patients with all AF forms as compared with control, but iNOS levels in post-ischemic patients were significantly higher than that in paroxysmal AF individuals. However, the levels of VEGF and AS did not differ from the baseline value in patients with paroxysmal AF, while dramatic increase of their contents was shown in post-stroke patients with persistent and permanent types of AF. Elevated active MMP-9 levels were shown to be associated with the diagnosis of all AF forms, regardless of the occurrence of stroke. Taken together, our findings demonstrate that tested proteins can be considered as valuable biomarkers of AF forms transformation and potentially useful for ischemic stroke risk stratification in patients with AF and CHF. Observed changes in regulatory protein levels may expand our understanding of pathological roles of endothelial function dysregulation, disrupted angiogenesis balance and abnormal tissue remodeling in AF and associated ischemic events.
Multiple effects of angiostatins in injured cornea
V. L. Bilous*, A. O. Tykhomyrov
Department of Enzyme Chemistry and Biochemistry, Palladin Institute of Biochemistry,
National Academy of Sciences of Ukraine, Kyiv;
*e-mail: basil.bilous@gmail.com
Received: 07 October 2023; Revised: 01 November 2023;
Accepted: 01 February 2024; Available on-line: 26 February 2024
Prolonged inflammation and excessive neovascularization of the cornea due to severe injury can impair optical clarity and lead to vision impairment. Plasminogen kringle (K) fragments, known as angiostatins (AS), play a well-established role as inhibitors of neovascularization by suppressing pro-angiogenic signaling. However, AS effects in the cornea, beyond inhibiting the angiogenesis, are still unexplored. In this study, we estimate the protective effect of two AS variants (K1-3 and K5) against alkali burn injury induced in rabbit and rat corneas. AS K1-3 in the single doses of 0.075 or 0.75 μg (0.1 or 1.0 μM, respectively) or 0.3 μg of AS K5 (1.0 μM) were applied locally as eye drops daily for 14 days after the injury. A significant regression of corneal vessels in-growth in injured eyes treated with AS was revealed. Western blot analysis of corneal tissue lysates revealed that injury-induced overexpression of protein markers of hypoxia (HIF-1α), angiogenesis (VEGF), tissue remodeling and fibrosis (MMP-9), autophagy (beclin-1) and endoplasmic reticulum stress (GRP-78) was significantly reduced under AS treatment. Besides, the level of tight junctions protein ZO-1 was shown to be up-regulated after the treatment of the damaged cornea with AS K1-3. Summarizing, our study uncovered novel biological functions of the kringle-containing plasminogen fragments indicating its beneficial effects during corneal healing in the experimental model of alkali burn. The data obtained can be helpful for the development of novel efficient formulations to manage complications of ocular surface injuries.
Plasminogen modulates formation and release of platelet angiogenic regulators
A. A. Tykhomyrov, D. D. Zhernosekov, T. V. Grinenko
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: artem_tykhomyrov@ukr.net
Received: 19 July 2019; Accepted: 29 November 2019
Platelets store, produce and release a variety of angiogenesis regulators, which can contribute to both normal tissue repair and angiopathy-associated pathologies. Plasminogen has been earlier shown to regulate some platelet functions, but if it is able to modulate angiogenic capacities of platelets is still poorly studied. Thus, the aim of the present study was to evaluate the effects of different plasminogen forms on the formation and secretion of angiogenic protein regulators by platelets. Human washed platelets were obtained by gel-filtration on Sepharose-2B. The levels of P-selectin (CD-62P) exposed on the plasma membrane of untreated and activated platelets was monitored by flow cytometry. Secretion of platelet-derived vascular endothelial growth factor (VEGF) as well as plasminogen fragmentation and angiostatin formation by intact platelets and platelet plasma membranes were analyzed by immunoblotting. It was shown that thrombin or collagen exposure resulted in enhanced P-selectin surface expression by platelets, while Lys-form of plasminogen reduced agonist-induced platelet secretion. Lys-plasminogen, but not Glu-form, inhibited agonist-induced VEGF release from platelets. Activation of platelets significantly accelerated plasminogen cleavage and angiostatin formation. Anti-actin antibodies inhibited plasminogen fragmentation during incubation with platelet plasma membranes indicating surface-exposed actin participation in plasminogen conversion to angiostatins. The present study uncovers a novel function of plasminogen to limit angiogenic potential of platelets via angiostatin formation and inhibition of VEGF secretion.
Levels of angiogenic regulators and MMP-2, -9 activities in Martorell ulcer: a case report
O. M. Petrenko1, A. A. Tykhomyrov2
1Bogomolets National Medical University, Kyiv, Ukraine;
2Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine;
e-mail: artem_tykhomyrov@ukr.net
Received: 27 July 2018; Accepted: 13 December 2018
Martorell hypertensive ischemic leg ulcers (HYTILU) represent a unique form of lower extremity non-healing ulcers that develop in association with poorly controlled high blood pressure. The present study was performed in order to assess levels of protein regulators of angiogenesis (vascular endothelial growth factor, or VEGF, and angiostatins) and to evaluate activities of matrix metalloproteinases (MMPs) (gelatinases MMP-2 and -9) in wound cutaneous tissue in the case of patient with 2-years HYTILU history. VEGF and angiostatin levels were analyzed by Western blot, MMP activities were evaluated by gelatin zymography. We report here for the first time that wound tissue in HYTILU is characterized with increased levels of VEGF (by 75 folds vs. histologically normal tissue, P < 0.01) and dramatic overproduction of angiostatin levels, which are undetectable in healthy cutaneous tissue. Approximately 10-fold elevation in MMP-2 and -9 activities is observed in wound tissue as compared with uninjured cutaneous tissue. Obtained results indicate that increased production of angiogenic inhibitors, angiostatins, may counteract VEGF-induced pro-angiogenic signaling, and together with MMP overactivation, contributes to failed healing of ischemic ulcer. Further extended studies are needed to clarify how changes of angiogenic profile and imbalance of proteolytic activities in non-healing Martorell ulcers can be considered during their management procedures to improve efficacy of surgery debridement and/or skin grafting.
Plasminogen and its fragments in rat brain: a plausible role for astrocytes in angiostatin generation
A. A. Tykhomyrov1, V. S. Nedzvetsky2,3, C. A. Ağca3,
V. V. Korsa1, T. V. Grinenko1
1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Dnipropetrovsk National University, Dnipro, Ukraine;
3Bingöl University, Bingöl, Turkey;
e-mail: artem_tykhomyrov@ukr.net
The purpose of the present study was to examine the plasminogen localization and to detect levels of its fragments (angiostatins) in various regions of rat brain as well as to establish whether rat brain astrocytes could be involved in angiostatin production. It was shown immunohistochemically that plasminogen is distributed broadly in the various brain regions, with predominant expression in meningeal layer and IV, V, and VI layers or cerebral cortex, dentate gyrus, meningeal and Purkinje cells, molecular and granular layers of cerebellum, as well as vessel walls. Angiostatin polypeptides were detected by Western blot analysis mostly in the cerebral cortex and were represented by 50 and 40-30 kDa polypeptides. In the whole cell lysates from primary cultures of rat astrocytes, immunoreactive polypeptides with Mm ~ 92, 84, 65-60, 50, 40, 38-30 kDa, corresponding to native plasminogen and a variety of its truncated products, including angiostatin polypeptides, were revealed. Incubation of astrocytes with exogenous plasminogen resulted in gradual increasing levels of some plasminogen fragments, particularly 30 kDa protein. Moreover, this polypeptide appeared to be the single angiostatin released by astrocytes in vitro. We report here for the first time that astrocytes are one of the cell types in CNS that could be responsible for angiostatin formation and releasing.