NOS2 and treatment resistant depression: Minocycline, an antibiotic with dual immunosuppressive function via its inhibition of the inflammasome (Caspase-1 and Caspase-3), pro-inflammatory enzymes (COX-2, inducible nitric oxide synthase [iNOS], matrix metalloproteinase [MMP], and phospholipase A2 [PLA2]), and immune cell proliferation/activation, also exerted anti-depressant effects in TRD patients and depressed HIV-infected subjects (146, 147).