Autophagy is a critical regulator of memory CD8(+) T cell formation

Generation of Natural Killer Cell Memory during Viral Infection

Immunological memory is classically regarded as an attribute of antigen-specific T and B lymphocytes of the adaptive immune system. Cells of the innate immune system, including natural killer (NK) cells, have been considered short-lived cytolytic cells that can rapidly respond against pathogens in an antigen-independent manner and then die off. However, NK cells have recently been described to possess traits of adaptive immunity, such as clonal expansion after viral antigen exposure to generate long-lived memory cells. In this review, we will discuss the current evidence for viral-induced NK cell memory in both mice and humans.

Environmental and metabolic sensors that control T cell biology

The T lymphocyte response to pathogens is shaped by the microenvironment. Environmental sensors in T cells include the nutrient-sensing serine/threonine kinases, adenosine monophosphate-activated protein kinase and mammalian target of rapamycin complex 1. Other environmental sensors are transcription factors such as hypoxia-inducible factor-1 and the aryl hydrocarbon receptor. The present review explores the molecular basis for the impact of environmental signals on the differentiation of conventional T cell receptor αβ T cells and how the T cell response to immune stimuli can coordinate the T cell response to environmental cues.

Requirement for autophagy in the long-term persistence but not initial formation of memory B cells

Autophagy is required for the long-term maintenance of Ag-specific memory B cells. However, whether autophagy is also important for the initial formation of memory B cells remains unclear. In this study, we show that newly generated memory B cells do not display active autophagy but are capable of forming Ab-secreting cells after rechallenge with Ags. Increases in autophagy took place over time after the initial formation of memory B cells. The expression of transcription factors involved in autophagy, but not changes in epigenetic regulation by DNA methylation, was required for autophagy gene expression and the development of active autophagy in memory B cells. This indicates that autophagy is not critical for the initial generation of memory B cells but is required for their long-term persistence. Our results suggest that promoting autophagy to improve Ab-dependent immunological memory is more effective during memory B cell maintenance stage.

Sugar, fat, and protein: new insights into what T cells crave

T cell activation and differentiation is a complex process that has evolved beyond the two-signal model to a number of varied and opposing inputs that must be interpreted to make a cell fate decision. While stimulation through the TCR, costimulatory, and cytokine receptors is required, metabolic signaling has emerged not only an activation signal, but one that can influence and shape differentiation. Recent findings have revealed unappreciated roles for glucose, fatty acids, and salt in the function of many T cell subsets. In this review, we will highlight the latest advances in the burgeoning field of immunometabolism, focusing on how the menu of T cell fuels has expanded.