3558 - Cardiomyocytes Upregulated the PD-L1 Expression to Alleviate Cardiac Injury Induced by Irradiation Combined with Anti-PD-1 Antibody: An In Vitro and In Vivo Study

02:30pm - 03:45pm PT

Hall F

Screen: 22

POSTER

Presenter(s)

Jun Wang, MD, PhD - Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei

Y. Zhou¹, Y. Wu², J. Wang², N. Zhang³, S. Wang⁴, X. S. Ye⁵, and Q. Li⁶; ¹Hebei General Hospital, Shijiazhuang, China, ²Department of Radiation Oncology, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China, ³Shijiazhuang People’s Hospital, Shijiazhuang, China, ⁴The Fourth Hospital of Hebei Medical University, Shijiazhuang, China, ⁵Clinical Medical College of Hebei University of Engineering, Handan, China, ⁶General Hospital of Hebei, Shijiazhuang, Hebei, China

Purpose/Objective(s):

Preclinical studies suggest that irradiation combined with anti-PD-1 antibody (iRT) exacerbates cardiac injury in mice, which is mediated by CD8-positive cell. We delivered with different irradiation doses and in combination with anti-PD-1 antibody to cardiomyocytes, both in vivo and in vitro, to investigated the PD-L1 expression in cardiomyocytes, and analyzed the underlying mechanisms.

Materials/Methods:

AC16 human cardiomyocytes (AC16 cells) were exposed to 0, 6Gy, or 10Gy irradiation. PD-L1 expression was assessed at 24h, 48h, and 72h by flow cytometry, qPCR, western blot, and immunofluorescence. Cell viability, apoptosis, and cytokine levels (IL-6, IL-10, MCP-1, CCL5, CXCL10) were detected. We knockdowned PD-L1 via siRNA (siPD-L1) to evaluate its function in AC16 cells. PBMCs or CD8+ T cells were co-cultured with siNC and siPD-L1 AC16 cells following irradiation at E:T 0:1, 5:1 and 10:1, and they were administrated with PD-1 inhibitors at different concentration. In vivo, C57BL/6J mice model of iRT-induced myocardial injury was established, and the heart tissue was analyzed for PD-L1 expression and CD8+T cells infiltration.

Results:

Irradiation with 10Gy upregulated PD-L1 expression on membrane, both in cytoplasm at 48h, and accumulation in the nucleus at 72h. After irradiation, the levels of IL-6, MCP-1, CCL5, and CXCL10 increased and IL-10 decreased in supernatant. Cardiomyocyte viability was inhibited, and apoptosis of cell increased. When PD-L1 was knockdowned in AC16 cells, we found cytokine release was exacerbated. Co-culture with activated CD8+ T cells inhibited cardiomyocyte viability, and this effect was dependent on CD8+T-cell density and co-culture time. In vivo, upregulation of PD-L1 in myocardial cells alleviate cardiac injury when combined irradiation with anti-PD-1 antibody, and survival were observed in mice without significant myocardial necrosis.

Conclusion:

PD-L1 Upregulation in cardiomyocytes might protect iRT-induced cardiac injury, which probably modulate inflammatory cytokines and CD8+ T-cell infiltration. CD8+ T-cell density and activation are the key issues in cardiomyocyte injury during iRT.