High-dose ascorbic acid potentiates immune modulation through STAT1 phosphorylation inhibition and negative regulation of PD-L1 in experimental sepsis

High dose Vitamin C inhibits PD-L1 by ROS-pSTAT3 signal pathway and enhances T cell function in TNBC

Vitamin C (VitC) presents excellent anti-tumor effect for long time. Recently, high dose VitC achieved by intravenous administration manifests superior anti-tumor effect. However, the functions and detailed mechanisms of high dose VitC's role in cancer immunity are not fully understood. This study investigates the effect of high dose VitC on PD-L1 expression in triple negative breast cancer (TNBC) and the potential mechanism. Results showed VitC inhibited PD-L1 expression in breast cancer cell lines and enhanced anti-tumor effects of T cells. Furthermore, we found VitC inhibited PD-L1 transcription through ROS-pSTAT3 signal pathways. Consistent with in vitro results, in vivo study showed VitC suppressed tumor growth in immunocompetent mice and enhanced CD8+ T cells infiltration and function in tumor microenvironment. Our findings identify the effects of high dose VitC on PD-L1 expression and provide a rationale for the use of high dose VitC as immunomodulator for cancer therapy.

The implication of targeting PD-1:PD-L1 pathway in treating sepsis through immunostimulatory and anti-inflammatory pathways

Sepsis currently remains a major contributor to mortality in the intensive care unit (ICU), with 48.9 million cases reported globally and a mortality rate of 22.5% in 2017, accounting for almost 20% of all-cause mortality worldwide. This highlights the urgent need to improve the understanding and treatment of this condition. Sepsis is now recognized as a dysregulation of the host immune response to infection, characterized by an excessive inflammatory response and immune paralysis. This dysregulation leads to secondary infections, multiple organ dysfunction syndrome (MODS), and ultimately death. PD-L1, a co-inhibitory molecule expressed in immune cells, has emerged as a critical factor in sepsis. Numerous studies have found a significant association between the expression of PD-1/PD-L1 and sepsis, with a particular focus on PD-L1 expressed on neutrophils recently. This review explores the role of PD-1/PD-L1 in immunostimulatory and anti-inflammatory pathways, illustrates the intricate link between PD-1/PD-L1 and sepsis, and summarizes current therapeutic approaches against PD-1/PD-L1 in the treatment and prognosis of sepsis in preclinical and clinical studies.