Small extracellular vesicles containing arginase-1 suppress T-cell responses and promote tumor growth in ovarian carcinoma.

Tumor-driven immune suppression is a major barrier to successful immunotherapy in ovarian carcinomas (OvCa). Among various mechanisms responsible for immune suppression, arginase-1 (ARG1)-carrying small extracellular vesicles (EVs) emerge as important contributors to tumor growth and tumor escape from the host immune system. Here, we report that small EVs found in the ascites and plasma of OvCa patients contain ARG1. EVs suppress proliferation of CD4+ and CD8+ T-cells in vitro and in vivo in OvCa mouse models. In mice, ARG1-containing EVs are transported to draining lymph nodes, taken up by dendritic cells and inhibit antigen-specific T-cell proliferation. Increased expression of ARG1 in mouse OvCa cells is associated with accelerated tumor progression that can be blocked by an arginase inhibitor. Altogether, our studies show that tumor cells use EVs as vehicles to carry over long distances and deliver to immune cells a metabolic checkpoint molecule - ARG1, mitigating anti-tumor immune responses.

Citation

Malgorzata Czystowska-Kuzmicz, Anna Sosnowska, Dominika Nowis, Kavita Ramji, Marta Szajnik, Justyna Chlebowska-Tuz, Ewa Wolinska, Pawel Gaj, Magdalena Grazul, Zofia Pilch, Abdessamad Zerrouqi, Agnieszka Graczyk-Jarzynka, Karolina Soroczynska, Szczepan Cierniak, Robert Koktysz, Esther Elishaev, Slawomir Gruca, Artur Stefanowicz, Roman Blaszczyk, Bartlomiej Borek, Anna Gzik, Theresa Whiteside, Jakub Golab. Small extracellular vesicles containing arginase-1 suppress T-cell responses and promote tumor growth in ovarian carcinoma. Nature communications. 2019 Jul 05;10(1):3000

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PMID: 31278254

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