Immune Checkpoint Dysregulation in Autoimmune Disorders: A Narrative Review of Therapeutic Implications

Immune checkpoints act like dimmer switches that keep immune responses in balance. In autoimmune disease, problems usually fall into four overlapping types: weak inhibitory signals, too much co-stimulation, metabolic or epigenetic rewiring of checkpoint pathways, and a mismatch between tissue and blood findings. This narrative review focused on human and translational studies from PubMed/Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica database (Embase), Web of Science, and Scopus (to 2025), prioritizing tissue-based data, trials of checkpoint agonists or co-stimulation blockade, cell-based tolerance (low-dose interleukin-2 (IL-2), chimeric antigen receptor regulatory T cells (CAR-Tregs), and extracellular vesicle (EV) approaches. Tissue profiling tracks disease activity better than blood alone. Immunometabolic stress, especially lactate-driven protein lactylation and ferroptosis, can blunt programmed cell death protein-1/cytotoxic T-lymphocyte associated protein-4 (PD-1/CTLA-4) braking and destabilize regulatory T cells (Tregs). A practical biomarker panel pairs lesion immunohistochemistry/spatial maps of PD-1/programmed death-ligand-1 (PD-L1) and second-wave checkpoints with soluble PD-1, PD-L1, CTLA-4, and EV cargo under strict pre-analytical control. Therapy should be staged: first, lower the inflammatory and metabolic load, then restore inhibitory tone with checkpoint agonists or co-stimulation blockade, and add Treg support and EV-guided delivery when regulation is fragile. Safety needs vaccine timing, age-/sex-aware dosing, and composite panels that distinguish flare from over-suppression. The next step is endotype-first, spatially informed, biomarker-anchored trials to achieve durable, safer immune rebalancing.