Bradykinin Receptor Antibodies

The bradykinin receptor family comprises two class A G protein-coupled receptors, B₁ and B₂, encoded by BDKRB1 and BDKRB2, respectively. B₂ is preferentially activated by bradykinin and kallidin, whereas B₁ responds to their C-terminally truncated metabolites, des-Arg⁹-bradykinin and des-Arg¹⁰-kallidin. Both receptors can couple to Gq/11, activating phospholipase C and increasing intracellular calcium. B₂ is constitutively expressed in many tissues, including vascular endothelium, smooth muscle, and sensory neurons, where it contributes to vasodilation, increased vascular permeability, and pain. B₁ expression is generally low under basal conditions and increases in response to inflammatory cytokines or tissue injury, contributing to inflammatory pain and hyperalgesia. Agonist stimulation typically induces rapid B₂ desensitization and internalization, whereas B₁ is relatively resistant to these processes in many experimental systems. The selective B₂ antagonist icatibant is approved for the treatment of acute attacks of hereditary angioedema. The oral B₁ antagonist BI 1026706 has been evaluated in patients with diabetic macular edema, and no selective B₁ antagonist is currently approved for therapeutic use.