Interleukin-7 and -15 maintain pathogenic memory Th17 cells in autoimmunity

Area of Science:

• Immunology
• Autoimmune Diseases
• Cellular Biology

Background:

• T helper 17 (Th17) cells are key players in autoimmune conditions.
• Memory Th17 cells are implicated in the chronicity of refractory autoimmune disorders.
• Mechanisms sustaining memory Th17 cells remain largely unknown.

Purpose of the Study:

• To investigate the mechanisms maintaining pathogenic memory Th17 cells in a preclinical model of ocular autoimmune disease.
• To identify key cytokines involved in the survival and proliferation of memory Th17 cells.
• To evaluate the therapeutic potential of targeting specific cytokines for autoimmune disease treatment.

Main Methods:

• Utilized a preclinical model of ocular autoimmune disease.
• Investigated the role of IL-7 and IL-15 in maintaining memory Th17 cells.
• Employed cytokine neutralization strategies.
• Analyzed STAT5 and Akt signaling pathways.
• Assessed Th17 cell populations in inflammatory sites and lymphoid tissues.

Main Results:

• Both IL-7 and IL-15 are critical for the maintenance of pathogenic memory Th17 cells.
• IL-7 and IL-15 provide survival signals through STAT5 activation.
• IL-15 additionally promotes proliferation via STAT5 and Akt activation.
• Topical neutralization of IL-7 or IL-15 reduced memory Th17 cells at target sites and draining lymph nodes.
• Neutralization of IL-17 alone did not reduce memory Th17 cells in draining lymphoid tissues.

Conclusions:

• Environmental IL-7 and IL-15 are essential for sustaining pathogenic memory Th17 cells.
• Targeting IL-7 or IL-15 presents a potential novel therapeutic strategy for autoimmune diseases.
• Blocking IL-7 or IL-15 may effectively eliminate pathogenic memory Th17 cells, offering a new treatment avenue.