Perivascular Tertiary Lymphoid Structures in Autoimmune Disease.

Immunotherapy of autoimmune diseases has expanded substantially, yet autoimmunity remains incurable, and patients suffer from chronic destructive tissue inflammation that fails to resolve. Mechanisms underlying the endurance of autoimmune memory and the lack of exhaustion are beginning to be understood. Here, we review emerging data on how decentralization of cellular immunity contributes to persistent autoimmune responses and chronicity of autoimmune tissue inflammation. Two processes are recognized as ensuring lasting immune memory: the generation of tissue-resident memory T cells (TRM) and the formation of tertiary lymphoid structures (TLS). TLS, lymphoid aggregates formed outside of lymphoid organs, develop under conditions of chronic immune stimulation, such as autoimmune disease, anti-tumor immunity, and during immune aging. TLS display heterogeneity in structure and cellular composition that may determine whether they ultimately serve as protective or pathogenic elements. Recent data have implicated TLS as a critical resource in upholding autoimmune responses, emphasizing their role in harming the host. In patients with autoimmune vasculitis, adventitial TLS drives protracted autoimmune disease by housing TCF1hi CD4+ T stem cells that escape exhaustion and provide a continuous supply of pathogenic effector T cells to the disease lesions. The local production and stemness of CD4+ T cells bring resilience to autoreactive immunity, defining novel therapeutic targets in the management of autoimmune disease.