Human CAR Tregs Targeting SOD1 and Expressing BDNF Reduce Inflammation and Delay Disease in G93A hSOD1-NSG Mice

Regulatory T cells (Tregs) have anti-inflammatory immunomodulatory activity and hold therapeutic potential for chronic neuroinflammatory neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS). We are developing engineered human Tregs with enhanced disease-modifying activity for treating ALS. A combination of a disease-specific chimeric antigen receptor (CAR) recognizing misfolded human superoxide dismutase-1 (hSOD1) and constitutive expression of brain-derived neurotrophic factor (BDNF) was tested. The scFv region of CAR demonstrated binding to anterior horn tissues of ALS patients with and without familial ALS mutations in SOD1. Tregs transduced to express BDNF showed the ability to secrete BDNF and protect co-cultured neuronal cells from peroxidase toxicity. Co-expression of BDNF did not inhibit CAR Treg expansion, Treg markers, or CAR-mediated anti-inflammatory cytokine production. Human Tregs co-expressing CAR and BDNF were tested for activity in G93A hSOD1-NSG transgenic mice, which develop an early-onset and aggressive ALS-like disease and do not reject human cells. Human Tregs expressing CAR and BDNF delayed the onset of disease development, extended survival, and decreased spinal cord neuroinflammation. The engineered Tregs showed enhanced disease-modifying activity and hold promise as a therapy for ALS.