Experimental strategies for the study of cellular immunity in renal disease

Renal failure associated with alternative medical therapies

Because the kidney is the major excretory organ for drugs and toxins, it is especially susceptible to damage from such agents. While alternative medical therapies appear to be on an increase worldwide, there have been few case reports regarding their nephrotoxicity. However we have recently observed three patients who developed irreversible renal impairment, which we believe was due to such therapies.

Molecular analysis of the helper T cell response in murine interstitial nephritis. T cells recognizing an immunodominant epitope use multiple T cell receptor V beta genes with similarities across CDR3

Anti-tubular basement membrane disease (alpha TBM disease) produces T cell-mediated interstitial nephritis in SJL mice after immunization with renal tubular antigen. Initial mononuclear infiltrates appear in vivo after several weeks, with the subsequent progression to renal fibrosis and end stage renal disease over many months. We have analyzed the fine specificity of the autoreactive helper T cell repertoire in alpha TBM disease through the isolation and characterization of a panel of CD4+ Th1 clones harvested after 1-2 wk from animals immunized to produce disease. All clones capable of mediating alpha TBM disease are directed towards a 14-residue immunodominant epitope (STMSAEVPEAASEA) contained within the target antigen, 3M-1. Evaluation of the T cell receptor (TCR) V beta repertoire used by these autoreactive T cells reveals the use of several V beta genes, but with some preference for V beta 14. Sequencing across the putative CDR3 region of the TCR beta chains suggests that common amino acids at the V beta(N)D beta junction and the D beta(N)J beta junction may contribute to the specific ability of these cells to recognize the immunodominant epitope.

Leflunomide (HWA 486) inhibits experimental autoimmune tubulointerstitial nephritis in rats

Experimental tubulointerstitial nephritis (TIN), induced in Brown Norway rats, is an autoimmune disorder in which afflicted animals display high levels of serum autoantibodies directed against antigens present on the tubular basement membrane (TBM). Serious functional damage, due to lesions of the kidney cortex, is evident 10 days after disease initiation. In an earlier study, we could show that cyclosporin A (CsA), an immunosuppressive drug, effectively prevented the onset of this illness, although it did not inhibit the formation of TBM autoantibodies. In the present study, the protective effects of CsA in autoimmune TIN was compared to those of drugs currently used to combat inflammatory ailments (i.e. prednisolone, indomethacin, naproxen, azathioprine) and a novel immunomodulating agent, leflunomide (HWA 486). Leflunomide is known to specifically inhibit the formation of T-dependent antibodies and is effective in preventing and curing animal autoimmune diseases, i.e. adjuvant arthritis disease of rats and murine lupus-like disorders. We found that not only could leflunomide inhibit TIN, but the drug-effects seemed to be more effective than those of CsA. Further, leflunomide was extremely effective in inhibiting the formation of autoantibodies to TBM, whereas CsA displayed only partial suppression. Neither prednisolone, indomethacin nor naproxen were effective in reducing the autoantibody titer, and did not offer any protection to the development of this disease. Together with the known effects on other autoimmune diseases we conclude that leflunomide is a novel immunointerventive drug protecting against several types of autoimmunity.

Cyclosporin A inhibits autoimmune experimental tubulointerstitial nephritis

Tubulointerstitial nephritis, regularly induced in Brown Norway rats by autosensitization with tubular basement membranes, appeared acutely at about 10 days and was completely inhibited by Cyclosporin A (CyA) when this was given before and at the time of onset of the disease. It did not recur after the end of therapy. In spite of this disease inhibition, autoantibodies against tubular basement membranes persisted in the circulation and in the kidney. It is therefore suggested that it is not so much the antibodies that are the decisive factors in the pathogenesis of this and other autoimmune diseases but, rather cellular factors that are directly influenced by CyA. Although in this model CyA application was a preventive measure, the experiments provide a cogent reason for the application of CyA as early as possible in acute and seriously damaging diseases.