The increased level of COX-dependent arachidonic acid metabolism in blood platelets from secondary progressive multiple sclerosis patients

Mol Cell Biochem (2016) 420:85–94 DOI 10.1007/s11010-016-2770-6 The increased level of COX-dependent arachidonic acid metabolism in blood platelets from secondary progressive multiple sclerosis patients Agnieszka Morel1 • Elzbieta Miller2,3 • Michal Bijak1 • Joanna Saluk1 Received: 20 March 2016 / Accepted: 9 July 2016 / Published online: 9 August 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract Platelet activation is increasingly postulated as a possible component of the pathogenesis of multiple sclerosis (MS), especially due to the increased risk of cardiovascular events in MS. Arachidonic acid cascade metabolized by cyclooxygenase (COX) is a key pathway of platelet activation. The aim of our study was to investigate the COX-dependent arachidonic acid metabolic pathway in blood platelets from secondary progressive multiple sclerosis (SP MS) patients. The blood samples were obtained from 50 patients (man n = 22; female n = 28), suffering from SP MS, diagnosed according to the revised McDonald criteria. Platelet aggregation was measured in platelet-rich plasma after arachidonic acid stimulation. The level of COX activity and thromboxane B2 concentration were determined by ELISA method. Lipid peroxidation was assessed by measuring the level of malondialdehyde. The results were compared with a control group of healthy volunteers. We found that blood platelets obtained from SP MS patients were more sensitive to arachidonic acid and their response measured as platelet aggregation was stronger (about 14 %) relative to control. We also observed a significantly increased activity of COX (about 40 %) and synthesis of thromboxane B2 (about 113 %). The generation of malondialdehyde as a marker of lipid peroxidation was about 10 % & Agnieszka Morel 1 Faculty of Biology and Environmental Protection, Department of General Biochemistry, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland 2 Department of Physical Medicine, Medical University of Lodz, Pl. Hallera 1, Lodz, Poland 3 Neurorehabilitation Ward, III General Hospital in Lodz, Milionowa 14, Lodz, Poland higher in SP MS than in control. Cyclooxygenase-dependent arachidonic acid metabolism is significantly increased in blood platelets of patients with SP MS. Future clinical studies are required to recommend the use of low-dose aspirin, and possibly other COX inhibitors in the prevention of cardiovascular risk in MS. Keywords Multiple sclerosis
Blood platelets
Arachidonic acid
Cyclooxygenase Introduction Multiple sclerosis (MS) is a chronic neuroinflammatory and immune-mediated disease associated with the formation of central nervous system (CNS) inflammatory plaques as well as lesions exhibiting extensive demyelination, along with loss of oligodendrocytes, neurons, and axons [1]. MS is considered as a heterogeneous neurological disease with various pathophysiological mechanisms and multiple clinical course, but closely related to the damage of intracerebral blood vessels, mainly as a result of increased permeability of blood–brain barrier (BBB) as well vessel occlusion [2]. There exists four subtypes of MS: relapsing-remitting (RR), secondary progressive (SP), primary progressive (PP), and progressive-relapsing (PR). The most prevalent form of MS is RR MS, in which the disease fluctuates between periods of inflammation and demyelination, and remission. Ultimately, after several years of disease duration, RR MS in approximately 70 % of cases, converts into a SP MS in which patients suffer irreversible disability progression. The progressive phase of MS is believed to be secondary to neurodegenerative changes triggered by inflammation. In progressive MS, as in relapsing-remitting MS, active tissue injury is associated 123 86 with inflammation, but the inflammatory response in SP MS occurs at least partly behind the blood–brain barrier [3]. PP MS is characterized by worsening neurologic function from the onset of symptoms, without relapses and remissions. PR MS is one of the rarest subtype of MS occurring in about 5 % of people with MS. In this subtype of MS a steadily worsening of the disease from the beginning and acute relapses are observed. The remissions do not occur in patients with PR MS [4]. Epidemiological studies confirm an increased risk of cardiovascular disease in MS, especially ischemic stroke and myocardial infarction that is acute events directly associated with abnormal platelet functions and their prothrombotic activity [5, 6]. It is thought that blood platelets play a crucial role in neurodegenerative processes, in which an excessive activation of platelets are observed [7]. A various bioactive compounds stored in platelet a-granules and released upon their activation may affect the permeability of BBB, and be crucial for the infiltration of T-lymphocytes, responsible for the dissemination of new inflammatory lesions in the CNS [8]. Our previous findings suggest that increased platelet activation may be an important cause of hemostatic disorders occurring in the progressive stage of MS (SP MS). Platelets are most likely important determinants in the pathogenesis of MS and actively participate in oxidative stress existing in SP MS [9]. Inhibition of platelet activation can provide measurable benefits in suppressing the disease process in MS. Upon platelet activation the signal transduction leads to mobilization of calcium and increases its intracellular concentration, resulting in phospholipases activation. These enzymes hydrolyze phospholipids of cell membrane, releasing e.g., the arachidonic acid (AA), which is a precursor of essential bioactive eicosanoids. AA is enzymatically transformed by the cyclooxygenase (COX) to intermediate products: prostaglandins and thromboxane A2 (TXA2), and then calcium is removed from intracellular storage sites [10, 11]. TXA2 is a potent blood platelet activator acting as proaggregatory and vasoconstrictor mediator, which plays a pivotal role in the growth and stabilization of a coronary thrombus [11]. This compound is formed in response to the local stimuli and it exerts its activating effect within a short distance of its biosynthesis. COX activation is associated with prothrombotic platelet activity and the production of proinflammatory eicosanoids. AA cascade metabolized by COX is a key pathway of platelet activation. The addition of AA to platelet-rich plasma in vitro, results in a burst of oxygen consumption, TXA2 formation, and platelet aggregation [12]. The major clinical indication for antiplatelet pharmacotherapy is the prevention of arterial thrombosis. Clinically used agents are based on interrupting specific sites in the sequence of platelet activation. The results of clinical studies have 123 Mol Cell Biochem (2016) 420:85–94 shown that intake of the antiplatelet agents as aspirin or different aspirin-like COX inhibitors, at low doses reduces the incidence of cardiovascular events [13 (...truncated)