The impaired distribution of adenosine deaminase isoenzymes in multiple sclerosis plasma and cerebrospinal fluid

Barbara Kutryb-Zajac; Ada Kawecka; Fionä Caratis; Krzysztof Urbanowicz; Alicja Braczko; Tomomi Furihata; Bartosz Karaszewski; Ryszard T Smolenski; Aleksandra Rutkowska

doi:10.3389/fnmol.2022.998023

The impaired distribution of adenosine deaminase isoenzymes in multiple sclerosis plasma and cerebrospinal fluid

Front Mol Neurosci. 2022 Sep 20:15:998023. doi: 10.3389/fnmol.2022.998023. eCollection 2022.

Authors

Barbara Kutryb-Zajac¹, Ada Kawecka¹, Fionä Caratis², Krzysztof Urbanowicz¹, Alicja Braczko¹, Tomomi Furihata³, Bartosz Karaszewski⁴, Ryszard T Smolenski¹, Aleksandra Rutkowska²

Affiliations

¹ Department of Biochemistry, Medical University of Gdańsk, Gdańsk, Poland.
² Department of Anatomy and Neurobiology, Medical University of Gdańsk, Gdańsk, Poland.
³ Laboratory of Clinical Pharmacy and Experimental Therapeutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan.
⁴ Department of Adult Neurology, Medical University of Gdańsk and University Clinical Center, Gdańsk, Poland.

Abstract

Background: Adenosine deaminase (ADA) via two isoenzymes, ADA1 and ADA2, regulates intra- and extracellular adenosine concentrations by converting it to inosine. In the central nervous system (CNS), adenosine modulates the processes of neuroinflammation and demyelination that together play a critical role in the pathophysiology of multiple sclerosis (MS). Except for their catalytic activities, ADA isoenzymes display extra-enzymatic properties acting as an adhesion molecule or a growth factor.

Aims: This study aimed to explore the distribution and activity of ADA1 and ADA2 in the plasma and the CSF of MS patients as well as in the human brain microvascular endothelial cells (HBMEC), human brain vascular pericytes and human astrocytes.

Methods and results: The enzyme assay following reverse phase-high performance liquid chromatography (HPLC) analysis was used to detect the ADA1 and ADA2 activities and revealed an increased ratio of ADA1 to ADA2 in both the plasma and the CSF of MS patients. Plasma ADA1 activity was significantly induced in MS, while ADA2 was decreased in the CSF, but significance was not reached. The brain astrocytes, pericytes and endothelial cells revealed on their surface the activity of ADA1, with its basal level being five times higher in the endothelial cells than in the astrocytes or the pericytes. In turn, ADA2 activity was only observed in pericytes and endothelial cells. Stimulation of the cells with pro-inflammatory cytokines TNFα/IL17 for 18 h decreased intracellular nucleotide levels measured by HPLC only in pericytes. The treatment with TNFα/IL17 did not modulate cell-surface ATP and AMP hydrolysis nor adenosine deamination in pericytes or astrocytes. Whereas in endothelial cells it downregulated AMP hydrolysis and ADA2 activity and upregulated the ADA1, which reflects the ADA isoenzyme pattern observed here in the CSF of MS patients.

Conclusion: In this study, we determined the impaired distribution of both ADA isoenzymes in the plasma and the CSF of patients with MS. The increased ADA1 to ADA2 ratio in the CSF and plasma may translate to unfavorable phenotype that triggers ADA1-mediated pro-inflammatory mechanisms and decreases ADA2-dependent neuroprotective and growth-promoting effects in MS.

Keywords: ADA1; ADA2; adenosine; adenosine deaminase (ADA); endothelium; multiple scleorsis (MS); nucleotides.