The PD-1:PD-L1 axis in Inflammatory Arthritis

Area of Science:

• Immunology
• Oncology
• Rheumatology

Background:

• T cell activation involves costimulatory and coinhibitory receptors.
• Programmed cell death protein 1 (PD-1) is a key coinhibitory receptor, crucial in oncology.
• PD-1/PD-L1 pathway blockade is effective in cancer treatment but can cause immune-related adverse events (irAEs).

Purpose of the Study:

• To review the biological distribution, function, and regulation of the PD-1 pathway.
• To explore the role of PD-1 in inflammatory arthritis (IA) and IA-related irAEs.
• To understand how PD-1 pathway defects contribute to spontaneous rheumatological diseases.

Main Methods:

• Literature review of PD-1 pathway biology.
• Analysis of PD-1's role in anti-tumour immunity.
• Investigation of PD-1's involvement in self-tolerance and autoimmune diseases.

Main Results:

• PD-1 blockade enhances anti-tumour immunity but can lead to self-reactive T cells.
• Emerging rheumatological irAEs, like IA, highlight PD-1's role in maintaining self-tolerance.
• Defects in the PD-1 pathway are implicated in the development of spontaneous rheumatological conditions.

Conclusions:

• The PD-1 pathway is critical for balancing anti-tumour immunity and self-tolerance.
• Understanding PD-1's role in IA and irAEs is essential for managing autoimmune side effects of cancer immunotherapy.
• Further research into PD-1 pathway defects may reveal mechanisms underlying rheumatological diseases.