Effects of vitamin D3 and cyclosporin A on HgCl2-induced autoimmunity in brown Norway rats.
BACKGROUND
Mercuric chloride (HgCl2) induces a lymphoproliferative disorder and autoimmune glomerulonephritis in Brown Norway (BN) rats. This syndrome is the consequence of T cell-dependent polyclonal B cell activation and autoantibody production. We have previously shown that HgCl2-induced autoimmune perturbations can be prevented in BN rats by the administration of cyclosporin A (CsA). The most potent vitamin D3 metabolite 1,25(OH)2 D3 (Vit D3) shares certain immunomodulatory properties with CsA. We therefore chose to compare the effects of Vit D3 to those of CsA in BN rats treated with HgCl2 in order to establish whether Vit D3 either alone or in combination with CsA can attenuate an autoimmune syndrome in vivo.


METHODS
BN rats were treated with HgCl2 according to a standard protocol. Subgroups of rats were also given CsA alone, Vit D3 or synthetic analogues of Vit D3 alone, or combinations of both agents. Different doses and routes of administration were compared. The following markers of disease activity were evaluated: mortality, peak proteinuria, serum IgE concentrations, and renal immunoglobulin deposition.


RESULTS
Disease activity was markedly attenuated in all rats treated with CsA alone. Vit D3 and certain of its synthetic analogues administered alone also tempered the autoimmune process, but to a lesser extent than did CsA. The effect of CsA alone was so potent, that no additive or synergistic effects could be demonstrated when CsA was administered in combination with Vit D3.


CONCLUSIONS
Despite similar described immunomodulatory effects in vitro, CsA is clearly more effective than Vit D3 in preventing HgCl2 autoimmune disease in BN rats. This suggests that there is a difference in the cellular targets of these two agents in vivo, and/or a difference in the potency with which HgCl2-triggered immune activation is suppressed.
Vendeville
B
B
McGill University, Montréal, Canada.
Baran
D
D
Gascon-Barré
M
M
D000818:Animals; D001327:Autoimmune Diseases / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D015551:Autoimmunity / Q000187:drug effects*; D002118:Calcium / Q000097:blood; D002762:Cholecalciferol / Q000627:therapeutic use*; D016572:Cyclosporine / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D005921:Glomerulonephritis / Q000139:chemically induced / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D007073:Immunoglobulin E / Q000097:blood; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008232:Lymphoproliferative Disorders / Q000139:chemically induced / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D008297:Male; D008627:Mercuric Chloride; D011507:Proteinuria / Q000188:drug therapy / Q000652:urine; D051381:Rats; D011914:Rats, Inbred BN; D012709:Serum Albumin / Q000378:metabolism
D007166:Immunosuppressive Agents; D012709:Serum Albumin; D002762:Cholecalciferol; D007073:Immunoglobulin E; D008627:Mercuric Chloride; D016572:Cyclosporine; D002118:Calcium