Assays for Monitoring Macroautophagy Activity in T cells

Insights into Autophagic Machinery and Lysosomal Function in Cells Involved in the Psoriatic Immune-Mediated Inflammatory Cascade

Impaired autophagy, due to the dysfunction of lysosomal organelles, contributes to maladaptive responses by pathways central to the immune system. Deciphering the immune-inflammatory ecosystem is essential, but remains a major challenge in terms of understanding the mechanisms responsible for autoimmune diseases. Accumulating evidence implicates a role that is played by a dysfunctional autophagy-lysosomal pathway (ALP) and an immune niche in psoriasis (Ps), one of the most common chronic skin diseases, characterized by the co-existence of autoimmune and autoinflammatory responses. The dysregulated autophagy associated with the defective lysosomal system is only one aspect of Ps pathogenesis. It probably cannot fully explain the pathomechanism involved in Ps, but it is likely important and should be seriously considered in Ps research. This review provides a recent update on discoveries in the field. Also, it sheds light on how the dysregulation of intracellular pathways, coming from modulated autophagy and endolysosomal trafficking, characteristic of key players of the disease, i.e., skin-resident cells, as well as circulating immune cells, may be responsible for immune impairment and the development of Ps.

Autophagy in inflammation, infection, and immunometabolism

Autophagy is a quality-control, metabolic, and innate immunity process. Normative autophagy affects many cell types, including hematopoietic as well as non-hematopoietic, and promotes health in model organisms and humans. When autophagy is perturbed, this has repercussions on diseases with inflammatory components, including infections, autoimmunity and cancer, metabolic disorders, neurodegeneration, and cardiovascular and liver diseases. As a cytoplasmic degradative pathway, autophagy protects from exogenous hazards, including infection, and from endogenous sources of inflammation, including molecular aggregates and damaged organelles. The focus of this review is on the role of autophagy in inflammation, including type I interferon responses and inflammasome outputs, from molecules to immune cells. A special emphasis is given to the intersections of autophagy with innate immunity, immunometabolism, and functions of organelles such as mitochondria and lysosomes that act as innate immunity and immunometabolic signaling platforms.

Activation-Induced Autophagy Is Preserved in CD4+ T-Cells in Familial Longevity

As with many other tissues and organs, the immune system is also affected by age. Immunosenescence is characterized by a decreased ability of immune cells to mount a productive response upon exposure to new antigens. Several studies have reported that members of families with exceptional longevity show improved immune function, which might contribute to the increased life- and health-span observed in those families. Autophagy is a catabolic process that delivers cytoplasmic material to the lysosomes for degradation. Defective autophagy is known to be associated with age in several cell types and tissues and its dysregulation is related to age-associated diseases. In T-cells, autophagy has an essential role in modulating protein and organelle homeostasis and in the regulation of activation-induced responses. In this study, using two different cohorts of individuals belonging to families with exceptional longevity, we show that CD4+ T-cells isolated from the offspring of parents with exceptional longevity show improved activation-induced autophagic activity compared with age-matched controls. Interestingly, increased autophagy is positively correlated with increased interferon-γ production. In conclusion, autophagy appears to be better maintained in members of families with extended longevity and positively correlates with improved T-cell function.

Key roles of autophagy in regulating T-cell function

In the past 10 years, autophagy has emerged as a crucial regulator of T-cell homeostasis, activation, and differentiation. Through the ability to adjust the cell's proteome in response to different stimuli, different forms of autophagy have been shown to control T-cell homeostasis and survival. Autophagic processes can also determine the magnitude of the T-cell response to TCR engagement, by regulating the cellular levels of specific signaling intermediates and modulating the metabolic output in activated T cells. In this review we will examine the mechanisms that control autophagy activity in T cells, such as ROS signaling and signaling through common gamma-chain cytokine receptors, and the different aspect of T-cell biology, including T-cell survival, effector cell function, and generation of memory, which can be regulated by autophagy.