Vladimir Rogovskii ^1,2* Vladimir Murugin ^2,3 Nikolay Vorobyev ^4,5 Sergey Popov ⁶ Nikolay Sturov ⁶ Alexey Krasheninnikov ⁷ Alexander Morozov ⁷ Marina Prokhorova ⁸

• ¹ Department of Molecular Pharmacology and Radiobiology, Pirogov Russian National Research Medical University, Moscow, Russia
• ² Department of Neuroimmunology, Federal Center of Brain Research and Neurotechnologies, Moscow, Moscow Oblast, Russia
• ³ Laboratory of Clinical Immunology, Institute of Immunology (Russia), Moscow, Moscow Oblast, Russia
• ⁴ Department of Oncology, P.Herzen Moscow Oncology Research Institute (MORI), Moscow, Moscow Oblast, Russia
• ⁵ I.M. Sechenov First Moscow State Medical University, Moscow, Moscow Oblast, Russia
• ⁶ Medical Institute, Department of General practice, Peoples' Friendship University of Russia, Moscow, Moscow Oblast, Russia
• ⁷ P.Herzen Moscow Oncology Research Institute (MORI), Moscow, Moscow Oblast, Russia
• ⁸ Institute for Personalized Oncology, Center for Digital Biodesign and Personalized Healthcare, I.M. Sechenov First Moscow State Medical University, Moscow, Moscow Oblast, Russia

Background: The natural killer (NK) activity of peripheral blood mononuclear cells (PBMCs) is a crucial defense against the onset and spread of cancer. Studies have shown that patients with reduced NK activity are more susceptible to cancer, and NK activity tends to decrease due to cancer-induced immune suppression. Enhancing the natural cytotoxicity of PBMCs remains a significant task in cancer research.Methods: This study investigates the potential of urolithin A, a polyphenolic metabolite produced by the gut microbiota, to enhance the natural cytotoxicity of PBMCs in prostate cancer patients and healthy subjects. We investigated the possible role of aryl hydrocarbon receptor (AhR) in this capability of urolithin A. We analyzed the ability of PBMCs preincubated with urolithin A, AhR agonist or antagonist to kill K562 (human chronic myelogenous leukemia) target cells.Our results demonstrate that urolithin A enhances the natural cytotoxicity of PBMCs in a dose-dependent manner. Specifically, at a concentration of 10 μM, urolithin A increased the NK activity of PBMCs from prostate cancer patients by an average of 23% (95% CI, 7%-38%). In addition, urolithin A modulates the level of cytokine production by PBMCs, decreasing the level of fractalkine, IL-8, and MCP-3. An AhR antagonist (CH223191, 1 μM) also increased NK activity, while an AhR agonist (β-naphthoflavone, 10 μM) did not increase NK activity and partially inhibited the urolithin A-induced enhancement.Urolithin A increases the NK activity of PBMCs from patients with prostate cancer and healthy subjects, and the AhR may be involved in this capability of urolithin A.