A novel benzodiazepine increases the sensitivity of B cells to receptor stimulation with synergistic effects on calcium signaling and apoptosis.
Bz-423 is a 1,4-benzodiazepine with selective lymphotoxic properties and potent therapeutic activity against lupus-like disease in autoimmune mice. In NZB/W lupus-prone mice, Bz-423 specifically kills germinal center B cells, which are the cells that drive disease both in this model and in human systemic lupus erythematosus. In this report, the mechanistic basis for the selective action of Bz-423 is investigated. We show that Bz-423-induces superoxide as an immediate early response and that this reactive oxygen species is more effective as a second messenger death signal in B cells activated by B cell receptor stimulation compared with resting cells. As a result, low [Bz-423] that are not cytotoxic to non-stimulated cells kill stimulated cells in synergy with anti-immunoglobulin M antibodies. Subsequent experiments demonstrated that Bz-423 extends the rise in intracellular calcium that accompanies anti-immunoglobulin M stimulation, and this effect mediates the synergistic death response. Because B cell hyperactivation and altered calcium signaling is a distinguishing feature of autoreactive lymphocytes in lupus, the mechanism by which Bz-423 induces apoptosis preferentially targets disease-causing cells on the basis of their activation state. Thus, molecules like Bz-423 could form the basis for new and selective anti-lupus agents.
Bednarski
Jeffrey J
JJ
Departments of Chemistry and Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Lyssiotis
Costas A
CA
Roush
Rebecca
R
Boitano
Anthony E
AE
Glick
Gary D
GD
Opipari
Anthony W
AW
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D001569:Benzodiazepines / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000378:metabolism; D004195:Disease Models, Animal; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D018858:Germinal Center / Q000166:cytology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000188:drug therapy; D008213:Lymphocyte Activation / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D015394:Molecular Structure; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
D002614:Chelating Agents; D005456:Fluorescent Dyes; D011947:Receptors, Antigen, B-Cell; D013481:Superoxides; D001569:Benzodiazepines; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C468549:Bz-423; D002118:Calcium