Selective regulation of IFN-γ and IL-4 co-producing unconventional T cells by purinergic signaling

Thymflammation: The Role of a Constitutively Active Inflammatory Network and "Ectopic" Cell Types in the Thymus in the Induction of T Cell Tolerance and Beyond

The thymus exhibits constitutive activation of nearly all major inflammatory pathways, including sterile MyD88-dependent signaling and interferon production by mTECs, the presence of cellular and molecular components of type 1, type 2, and type 3 responses, as well as sustained B cell activation. The reasons for the existence of such a complex constitutively active inflammatory network at the site of T cell development-where the initial pathogen encounter is unlikely-have remained enigmatic. We propose that this inflammatory thymic 'ecosystem' has evolved to promote immunological tolerance to 'inflammatory self'-endogenous molecules absent from most peripheral tissues at steady state but upregulated during pathogen invasion. The spatial and temporal overlap with pathogen presence makes the discrimination of the inflammatory self from pathogen-derived molecules a unique challenge for the adaptive immune system. The frequent occurrence of diseases associated with autoantibodies against proinflammatory cytokines underscores the persistent risk of these molecules being misidentified as foreign. Their abundant representation in the thymus, therefore, is likely to be critical for maintaining tolerance. This review explores current insights into the thymic inflammatory network, its cellular and molecular constituents, and their role in the induction of T cell tolerance.

Interacting roles of gut microbiota and T cells in the development of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a progressive liver inflammatory disease mediated by an autoimmune response, with an increasing incidence rate. In severe cases, AIH will rapidly progress to liver cirrhosis and liver failure and even lead to death. The gut microbiota is a complex ecosystem that significantly regulates physiological and pathological processes among various digestive system diseases. It is widely acknowledged that there is a critical correlation between AIH and the gut microbiota. Numerous studies have demonstrated that the composition of gut microbiota in individuals with AIH differs markedly from that of healthy subjects. Immune cells, especially T cells, are pivotal in the development of AIH, closely interacting with the gut microbiota. In this review, we discuss the regulatory role of the gut microbiota in T cell-mediated development of AIH, as well as the effect of T cells on the composition of the gut microbiota in AIH. By modulating gut microbiota or immunity pathways, novel opportunities are provided to regulate the balance of the immune-microbial microenvironment, targeting the dual factor for autoimmune hepatitis therapies.

An unconventional purine connection

Xu et al. (https://doi.org/10.1084/jem.20240354) define NAD-induced cell death via purinergic P2RX7 receptor in type 1 unconventional T cells, particularly intrahepatic MAIT cells that are pivotal in liver homeostasis. Therefore, P2RX7 is a potential target to modulate unconventional T cells in immunopathological conditions and cancer.