PTPN6/SHP-1 in autoimmune disease: immune tolerance, regulatory mechanisms, and therapeutic targeting.

PTPN6 encodes SHP-1, a central regulator of immune tolerance and a critical signaling brake across innate and adaptive immunity in autoimmune disease. Predominantly expressed in hematopoietic cells, SHP-1 restrains receptor-proximal signaling downstream of antigen, cytokine, and pattern-recognition receptors, thereby setting activation thresholds that preserve immune homeostasis and limit autoreactivity. Converging evidence from human genetics, patient-derived immune cells, and animal models indicates that diminished SHP-1 activity promotes persistent autoreactive lymphocyte responses, exaggerated inflammatory signaling, and tissue-specific injury across systemic lupus erythematosus, rheumatoid arthritis, neutrophilic dermatoses, multiple sclerosis, psoriasis, and type 1 diabetes. Beyond its role in disease pathogenesis, SHP-1 has emerged as a therapeutically relevant node, particularly through strategies designed to enhance phosphatase activity and restore immune restraint. However, clinical translation remains constrained by challenges in phosphatase selectivity, context-dependent biology, and tissue-specific delivery. This review integrates current understanding of SHP-1 regulatory mechanisms, disease-specific evidence, and emerging translational opportunities, highlighting PTPN6/SHP-1 as a candidate target for precision immunomodulation in autoimmune disease.