Effect Of Galectin-1 On Myeloid-Derived Suppressor Cell Exosomes Immunosuppressive Activity

BACH, CA.; PERROTTA, RM.; MERLO, JP.; MANSELLE-COCCO, MN.; BLIDNER, AG.; RABINOVICH, GA.

Congreso; Reunion Anual de Biociencias 2021; 2021

SAIC-SAI

Myeloid-Derived Suppressor Cells (MDSC) represent a major hurdle for cancer immunotherapy by blunting antitumor T-cell responses. Emerging evidence suggests that MDSC may promote immunosuppression via exosomes shedding; however, the molecular mediators that trigger this effect are still elusive. We have recently demonstrated that Galectin 1 (Gal1), a b-galactoside-binding protein, enhances both the immunosuppressive and pro-angiogenic activities of MDSC-derived exosomes. Here, we aimed to described Gal1 role in MDSC exosomes biology. We have differentiated MDSC from mouse bone marrow cells in vitro, incubated them with recombinant Gal1 (MDSC-Gal1), and isolated the exosomes shed (control MDSC-exo or MDSC-Gal1-exo). We have characterized MDSC-exo and their parental cell population by flow cytometry. Interestingly, CD63, a well-established marker of tumoral exosomes, was not detected on MDSC-exo surface. In contrast, we have detected high expression of MHC II on MDSC-exo surface. Notably, Gal1 induced heightened PD-L1 and IDO expression on MDSC-exo (p