Rapid metabolic regulation of a novel arginine methylation of KCa3.1 attenuates T cell exhaustion.

T cell exhaustion is linked to persistent antigen exposure and perturbed activation events, correlating with poor disease prognosis. Tumor-mediated T cell exhaustion is well documented; however, how the nutrient-deprived tumor niche affects T cell receptor (TCR) activation is largely unclear. We show that methionine metabolism licenses optimal TCR signaling by regulating the protein arginine methylome, and limiting methionine availability during early TCR signaling promotes subsequent T cell exhaustion. We discovered a novel arginine methylation of a Ca 2+ -activated potassium transporter, KCa3.1, prevention of which results in increased Ca 2+ -mediated NFAT1 activation, NFAT1 promoter occupancy, and T cell exhaustion. Furthermore, methionine supplementation reduces nuclear NFAT1 in tumor-infiltrating T cells and augments their anti-tumor activity. These findings demonstrate metabolic regulation of T cell exhaustion determined during TCR engagement.

Peptide-scFv antigen recognition domains effectively confer CAR T cell multiantigen specificity.

The emergence of immune escape is a significant roadblock to developing effective chimeric antigen receptor (CAR) T cell therapies against hematological malignancies, including acute myeloid leukemia (AML). Here, we demonstrate feasibility of targeting two antigens simultaneously by combining a GRP78-specific peptide antigen recognition domain with a CD123-specific scFv to generate a peptide-scFv bispecific antigen recognition domain (78.123). To achieve this, we test linkers with varying length and flexibility and perform immunophenotypic and functional characterization. We demonstrate that bispecific CAR T cells successfully recognize and kill tumor cells that express GRP78, CD123, or both antigens and have improved antitumor activity compared to their monospecific counterparts when both antigens are expressed. Protein structure prediction suggests that linker length and compactness influence the functionality of the generated bispecific CARs. Thus, we present a bispecific CAR design strategy to prevent immune escape in AML that can be extended to other peptide-scFv combinations.

The Mechanisms of Altered Blood-Brain Barrier Permeability in CD19 CAR T-Cell Recipients.

Cluster of differentiation 19 (CD19) chimeric antigen receptor (CAR) T cells are a highly effective immunotherapy for relapsed and refractory B-cell malignancies, but their utility can be limited by the development of immune effector cell-associated neurotoxicity syndrome (ICANS). The recent discovery of CD19 expression on the pericytes in the blood-brain barrier (BBB) suggests an important off-target mechanism for ICANS development. In addition, the release of systemic cytokines stimulated by the engagement of CD19 with the CAR T cells can cause endothelial activation and decreased expression of tight junction molecules, further damaging the integrity of the BBB. Once within the brain microenvironment, cytokines trigger a cytokine-specific cascade of neuroinflammatory responses, which manifest clinically as a spectrum of neurological changes. Brain imaging is frequently negative or nonspecific, and treatment involves close neurologic monitoring, supportive care, interleukin antagonists, and steroids. The goal of this review is to inform readers about the normal development and microstructure of the BBB, its unique susceptibility to CD19 CAR T cells, the role of individual cytokines on specific elements of the brain's microstructural environment, and the clinical and imaging manifestations of ICANS. Our review will link cellular pathophysiology with the clinical and radiological manifestations of a complex clinical entity.