SARSIMM

Molecular mechanism of the anti-inflammatory action of heparin International Journal of Molecular Sciences Vol. 22(19) (2021) 10730

Authors: Leandar Litov*, Peicho Petkov, Miroslav Rangelov, Nevena Ilieva, Elena Lilkova, Nadezhda Todorova, Elena Krachmarova, Kristina Malinova, Anastas Gospodinov, Rossitsa Hristova, Ivan Ivanov, and Genoveva Nacheva

Abstract: Our objective is to reveal the molecular mechanism of the anti-inflammatory action of low-molecular-weight heparin (LMWH) based on its influence on the activity of two key cyto-kines, IFNγ and IL-6. The mechanism of heparin binding to IFNγ and IL-6 and the resulting inhi-bition of their activity were studied by means of extensive molecular-dynamics simulations. The effect of LMWH on IFNγ signalling inside stimulated WISH cells was investigated by measuring its antiproliferative activity and the translocation of phosphorylated STAT1 in the nucleus.

We find that LMWH binds with high affinity to IFNγ and is able to fully inhibit the interaction with its cellular receptor. It also influences the biological activity of IL-6 by binding to either IL-6 or IL-6/IL-6Rα thus preventing the formation of the IL-6/IL-6Rα/gp130 signalling complex. These findings shed light on the molecular mechanism of the anti-inflammatory action of LMWH and underpin its ability to influence favourably conditions characterised by overexpression of these two cytokines. Such conditions are associated with autoimmune diseases, but also with inflam-matory processes, in particular with COVID-19. Our results put forward heparin as a promising means for prevention and suppression of severe CRS and encourage further investigations on its applicability as an anti-inflammatory agent.

Keywords: molecular dynamics; molecular modelling; cytokine storm; inflammation; low-molecular-weight heparin (LMWH); IFNγ; IL-6; signalling pathway; COVID-19

Journal metric: IF = 5.923; Q1 in the category Biochemistry & Molecular Biology of JCR.

https://www.mdpi.com/1422-0067/22/19/10730   Open Access article   complete article

Computational Study of IL-6 Inhibition by Low-Molecular-Weight Heparin International Conference on Large Scale Scientific Computations (LSSC'21) 7-11 June 2021, Sozopol, Bulgaria & online

Authors: Peicho Petkov, Miroslav Rangelov, Nevena Ilieva, Nadezhda Todorova, Elena Lilkova*, Leandar Litov

Interleukine 6 (IL-6) is a pleiotropic cytokine with an important role in inflammation, immune response, and hematopoiesis. The intracellular signalling is initiated after a two-stage process of formation of the triple complex of IL-6, IL-6 receptor (IL-6Rα) and a second membrane protein, glycoprotein 130 (gp130), and its subsequent dimerisation. Aberrant IL-6 levels are associated with chronic inflammation and autoimmunity. In addition, the cytokine has been recognized as a key participant in the development of an acute severe systemic inflammatory response – the acute cytokine release syndrom (CRS), known also as cytokine storm (CS). Therefore, searching for an inhibitor of the IL-6 signalling cascade is of interest for the management and treatment of CS. One possible candidate, able to bind to IL-6 is low-molecular-weight heparin (LMWH). LMWH are highly sulfated polysaccharide chainswith a very highelectric-charge density, determining their very high biological activity.

Here, we report the results of a computational study of the interaction of LMWH hexasaccharides with IL-6 and the macromolecular complexes IL-6/IL-6Ralpha and IL-6/IL-6R/gp130. We show that heparin forms a stable complex with IL-6, blocking one of its binding sites and thus inhibiting the formation of the IL-6/IL-6R complex. In addition, LMWH molecules also bind to the IL-6/IL-6Ralpha complex, blocking another binding site in IL-6, and thus preventing proper recruitment of the gp130 receptor. Our results reveal the mechanism of heparin inhibitory action on the IL-6 activity.

LSSC'2021     Book of Abstracts

Molecular mechanism of the anti-inflammatory action of heparin: a computational perspective of the COVID-19 case International Conference BIOMATH 2021 20-25 June 2021, Pretoria, South Africa & online

Authors: N. Ilieva*, P. Petkov, M. Rangelov, N. Todorova, and L. Litov

We perform in silico study of the ability of low-molecular-weight heparin (LMWH) to inhibit both IFNγ and IL-6 signalling pathways. While heparin's binding affinity to these cytokines is well-known, the molecular mechanism of its impact on their biological activity has not been studied in detail. Our results show that LMWH is able to fully inhibit the interaction of IFNγ with its cellular receptor, thus blocking the IFNgamma signalling pathway. It also influences the biological activity of IL-6 by preventing the formation of the IL-6/IL-6Rα/gp130 signalling complex. These findings shed light on the molecular mechanism of the anti-inflammatory action of LMWH, relating it to the impairment of the biological activity of these cytokines, and underpin heparin's ability to influence favourably conditions characterised by overexpression of the latter. Such conditions are associated with autoimmune diseases, but also with inflammatory processes, in particular with COVID-19. Our results put forward heparin as a promising means for prevention and suppression of the development of severe CRS in acute COVID-19 patients and encourage further investigations on its applicability as an anti-inflammatory agent.

BIOMATH 2021

LMWH as a prospective IL-6 blocker: a computational study Thirteenth Conference of the Euro-American Consortium for Promoting the Application of Mathematics in Technical and Natural Sciences (AMiTaNS'2021), Albena, Bulgaria, June 24-29, 2021

Authors: P. Petkov, M. Rangelov, N. Ilieva, N. Todorova, E. Lilkova*, and L. Litov

Interleukine 6 (IL-6) is a signalling molecule, that has both pro- and anti-inflammatory functions and plays an important role in inflammation, immune response, and hematopoiesis. IL-6 signalling requires a two-stage process: firstly, the cytokine binds to the IL-6 receptor (IL-6Ra) and then a second membrane protein, glycoprotein 130 (gp130) is recruited to form a triple complex, which subsequently dimerises. Elevated IL-6 levels are associated with chronic inflammation and autoimmunity. Moreover, the cytokine was found to play a key role in the development of an acute severe systemic inflammatory response – the acute cytokine release syndrome (CRS), known also as cytokine storm (CS). Hence, inhibition of the IL-6 signalling has great potential in the management and treatment of CS.

In this work we study the interaction of IL-6 with a potential IL-6 inhibitor – low-molecular-weight heparin (LMWH). LMWH are highly positively charged polysaccharide chains. In particular, we performed computer simulations of IL-6, and IL6-IL6Ralpha with a particular hexasaccharide that models a general LMWH chain. Our results reveal the mechanism of heparin inhibitory action on the IL-6 activity.

AMiTaNS 2021     Book of Abstracts

Computational study of the molecular mechanism of LMWH anti-inflammatory action: a COVID-19 perspective 50th Jubilee Conference of the Union of Bulgarian Mathematicians Burgas, September 1-5, 2021 (national conference)

Authors: N. Ilieva*, P. Petkov, M. Rangelov, E. Lilkova, N. Todorova, and L. Litov

50th Conference of UBM     Programme

In silico study of the molecular mechanism of LMWH antiinflammatory action within the Covid-19 context International Workshop "Mathematics of Life (MoL2021)" 13-16 September 2021, Hisarya, Bulgaria & online

Authors: N. Ilieva*, P. Petkov, M. Rangelov, E. Lilkova, N. Todorova, and L. Litov

We perform in silico study of the ability of low-molecular-weight heparin (LMWH) to inhibit both IFNγ and IL-6 signalling pathways. While heparin's binding affinity to these cytokines is well-known, the molecular mechanism of its impact on their biological activity has not been studied in detail. Our results show that LMWH is able to fully inhibit the interaction of IFNγ with its cellular receptor, thus blocking the IFNγ signalling pathway. It also influences the biological activity of IL-6 by preventing the formation of the IL-6/IL-6Rα/gp130 signalling complex. These findings shed light on the molecular mechanism of the anti-inflammatory action of LMWH, relating it to the impairment of the biological activity of these cytokines, and underpin heparin's ability to influence favourably conditions characterised by overexpression of the latter. Such conditions are associated with autoimmune diseases, but also with inflammatory processes, in particular with COVID-19. Our results put forward heparin as a promising means for prevention and suppression of the development of severe CRS in acute COVID-19 patients and encourage further investigations on its applicability as an anti-inflammatory agent.

MoL2021     Book of Abstracts

In silico study of the antiinflammatory action of heparin within the Covid-19 context PRACE Autumn School 2021: Fundamentals of Biomolecular Simulations and Virtual Drug Development September 20-24, 2021, Sofia, Bulgaria & online

Authors: N. Ilieva*, P. Petkov, M. Rangelov, E. Lilkova, N. Todorova, and L. Litov

PRACE Autumn School 2021     Lectures

Cytokines activity impairment through heparin — molecular mechanism and therapeutic potential Workshop on Numerical and Symbolic Scientific Computing 20-23 September 2021, Sofia, Bulgaria & online

Authors: N. Ilieva*, P. Petkov, M. Rangelov, E. Lilkova, N. Todorova, and L. Litov

NSSC     Programme

Heparan Sulfate facilitates binding of hIFN? to its cell-surface receptor hIFNGR1 International Journal of Molecular Sciences Vol. 23(16) (2022) 9415

Authors: Elisaveta Miladinova, Elena Lilkova, Elena Krachmarova, Kristina Malinova, Peicho Petkov, Nevena Ilieva, Genoveva Nacheva, Leandar Litov

Abstract: Human interferon-gamma (hIFNγ) is a crucial signaling molecule with an important role in the initialization and development of the immune response of the host. However, its aberrant activity is also associated with the progression of a multitude of autoimmune and other diseases, which determines the need for effective inhibitors of its activity. The development of such treatments requires proper understanding of the interaction of hIFNγ to its cell-surface receptor hIFNGR1. Currently, there is no comprehensive model of the mechanism of this binding process. Here, we employ molecular dynamics simulations to study on a microscopic level the process of hIFNγ-hIFNGR1 complex formation in different scenarios. We find that the two molecules alone fail to form a stable complex, but the presence of heparan-sulfate-like oligosaccharides largely facilitates the process by both demobilizing the highly flexible C-termini of the cytokine and assisting in the proper positioning of its globule between the receptor subunits. An antiproliferative-activity assay on cells depleted from cell-surface heparan sulfate (HS) sulfation together with the phosphorylation levels of the signal transducer and activator of transcription STAT1 confirms qualitatively the simulation-based multistage complex-formation model. Our results reveal the key role of HS and its proteoglycans in all processes involving hIFNγ signalling

Keywords: human interferon gamma; human interferon gamma receptor; heparan sulfate; molecular dynamics simulations; sodium chlorate

Journal metric: IF = 6.203; Q1 in the category Biochemistry & Molecular Biology of JCR.

https://doi.org/10.3390/ijms23169415   Open Access article   complete article

Computational modeling of the replicase-transcriptase complex of SARS-CoV-2 Numerical Solutions of Fractional Differential Equations and Applications (IICT - Bulgarian Academy of Sciences, Sofia, 2022: ISBN:978-619-7320-10-7), pp 70-72

Authors: Nadezhda Todorova, Miroslav Rangelov, Peicho Petkov, Nevena Ilieva, Elena Lilkova, Leandar Litov

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