Significantly Boosted Th2-Selective Activity of NKT Cell Agonist Enabled by Sulfonamide Hydrogen-Bond Design.

Natural killer T (NKT) cell agonists can serve as promising immunotherapeutic agents by tuning proinflammatory (Th1) or anti-inflammatory (Th2) effects. Th2-biased NKT cell agonists often derive from truncating lipid chains but usually have activity lower than that of the parental glycolipid αGalCer. This study identified highly potent Th2-biased αGalCer analogs through structure-guided sulfonamide modification, aiming to introduce additional hydrogen bonds within the glycolipid/CD1d complex. The lead compound GCS-12-6, featuring an optimally shortened acyl chain, demonstrated a remarkable 6.7-fold increase of stimulatory activity and 76-fold enhancement of Th2 selectivity compared to αGalCer in vivo. These results establish GCS-12-6 as one of the most potent Th2-biased NKT cell agonists. Notably, GCS-12-6 showed rapid ligand presentation by CD1d on the antigen-presenting cells. Moreover, GCS-12-6 demonstrated effective protection against intestinal inflammation. The sulfonamide derivation based on structure and binding affinity optimization provides valuable insights for designing potent and biased NKT cell agonists as effective immune modulators.