Systems approach reveals distinct and shared signaling networks of the four PGE2 receptors in T cells

PGE2 inhibits TIL expansion by disrupting IL-2 signalling and mitochondrial function

Expansion of antigen-experienced CD8+ T cells is critical for the success of tumour-infiltrating lymphocyte (TIL)-adoptive cell therapy (ACT) in patients with cancer1. Interleukin-2 (IL-2) acts as a key regulator of CD8+ cytotoxic T lymphocyte functions by promoting expansion and cytotoxic capability2,3. Therefore, it is essential to comprehend mechanistic barriers to IL-2 sensing in the tumour microenvironment to implement strategies to reinvigorate IL-2 responsiveness and T cell antitumour responses. Here we report that prostaglandin E2 (PGE2), a known negative regulator of immune response in the tumour microenvironment4,5, is present at high concentrations in tumour tissue from patients and leads to impaired IL-2 sensing in human CD8+ TILs via the PGE2 receptors EP2 and EP4. Mechanistically, PGE2 inhibits IL-2 sensing in TILs by downregulating the IL-2Rγc chain, resulting in defective assembly of IL-2Rβ-IL2Rγc membrane dimers. This results in impaired IL-2-mTOR adaptation and PGC1α transcriptional repression, causing oxidative stress and ferroptotic cell death in tumour-reactive TILs. Inhibition of PGE2 signalling to EP2 and EP4 during TIL expansion for ACT resulted in increased IL-2 sensing, leading to enhanced proliferation of tumour-reactive TILs and enhanced tumour control once the cells were transferred in vivo. Our study reveals fundamental features that underlie impairment of human TILs mediated by PGE2 in the tumour microenvironment. These findings have therapeutic implications for cancer immunotherapy and cell therapy, and enable the development of targeted strategies to enhance IL-2 sensing and amplify the IL-2 response in TILs, thereby promoting the expansion of effector T cells with enhanced therapeutic potential.

Controlling Inflammation Improves Aging Skeletal Muscle Health

Chronic inflammation is associated with a decline in aging skeletal muscle health. Inflammation also seems to interfere with the beneficial skeletal muscle adaptations conferred by exercise training in older individuals. We hypothesize that the cyclooxygenase pathway is partially responsible for this negative inflammatory influence on aging skeletal muscle health and plasticity.

Immunoregulatory signal networks and tumor immune evasion mechanisms: insights into therapeutic targets and agents in clinical development

Through activation of immune cells, the immune system is responsible for identifying and destroying infected or otherwise damaged cells including tumorigenic cells that can be recognized as foreign, thus maintaining homeostasis. However, tumor cells have evolved several mechanisms to avoid immune cell detection and killing, resulting in tumor growth and progression. In the tumor microenvironment, tumor infiltrating immune cells are inactivated by soluble factors or tumor promoting conditions and lose their effects on tumor cells. Analysis of signaling and crosstalk between immune cells and tumor cells have helped us to understand in more detail the mechanisms of tumor immune evasion and this forms basis for drug development strategies in the area of cancer immunotherapy. In this review, we will summarize the dominant signaling networks involved in immune escape and describe the status of development of therapeutic strategies to target tumor immune evasion mechanisms with focus on how the tumor microenvironment interacts with T cells.

GPCR Systems Pharmacology: A Different Perspective on the Development of Biased Therapeutics

G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and are the target of approximately one-third of all Food and Drug Administration (FDA)-approved pharmaceutical drugs. GPCRs interact with many transducers, such as heterotrimeric G proteins, GPCR kinases (GRKs), and β-arrestins. Recent experiments have demonstrated that some ligands can activate distinct effector proteins over others, a phenomenon termed biased agonism. These discoveries have raised the potential of developing drugs which preferentially activate therapeutic signaling pathways over those that lead to deleterious side effects. However, to date, only one biased GPCR therapeutic has received FDA approval and many others have either failed to meet their specified primary endpoints and or demonstrate superiority over currently available treatments. Additionally, there is a lack of understanding regarding how biased agonism measured at a GPCR leads to specific downstream physiologic responses. Here, we briefly summarize the history and current status of biased agonism at GPCRs and suggest adoption of a systems pharmacology approach upon which to develop GPCR-targeted drugs that demonstrate heightened therapeutic efficacy with improved side effect profiles.