Cyclosporine animal models

Hypertension is associated with increased TXA2 and decreased PGE2 and PGI2 synthesis in some animal models, eg, the Goldblatt kidney model. It is not known whether these changes are primary contributing factors or secondary responses. Similarly, increased TXA2 formation has been reported in cyclosporine-induced nephrotoxicity, but no causal relationship has been established. 

As is true for all biopharmaceuticals, toxicity studies should be performed in relevant animal models. For cellular therapies these models are often in animal models intended to mimic the human disease. When possible the intended human cells are utilized for assessments with or without low-dose immunosuppressants (e.g., lOmg/kg, i.p. dose of cyclosporine A in rats). The immunosuppressive drug is generally administered prior to the cell dose and extended for a specified period after the transplant. In cases where it is not feasible to use the intended clinical material, largely due to the inability of the cells to engraft sufficiently into the host, analogous cells can be used to assess preclinical safety and activity. In such cases it is important to understand the potential impact of any differences between the analogous product and the clinical product in order to improve extrapolation of safe and active cell doses to humans. 

Relatively non-specific T cell immunosuppression has been successful in animal models. Treatment of hypersensitivity pneumonitis in mice with cyclosporin A led to improvement of the disease as seen by an abrogation of the increase in lung index, lack of IL-1 and TNFa release in BAL (Denis etal., 1992). However, this drug has not proven to be useful in clinical lung fibrosis in humans. 

Additional studies carried out in animal models of temporal lobe epilepsy (TLE) further support the use of selective ABCBl inhibitors to reverse drug resistance in RE. Thus, tariquidar potentiates the effect of phenytoin and countervails resistance to phenobarbital in a rat model of TLE. Furthermore, cyclosporin A helps reverse resistance to phenytoin in a rat model of AED-resistant status epilepticus. Finally, verapamil counteracts resistance to oxacarbazepine in rats with pilocarpine-induced seizures [42]. 

Models of rheumatoid arthritis (RA) were object to l,25(OH)2D3 treatment, providing additional support for the high potential of the hormone for the treatment of Thl-mediated diseases. As an example, in rat adjuvant arthritis l,25(OH)2D3 improved the inhibiting effect of cyclosporine A on arthritis onset as well as on arthritis aggravation [142]. The incidence and severity of type II collagen-induced arthritis was reduced in rats or mice orally treated with 25-(OH)2-D3, the 1,25 (OH)2D3 analog MC 1288 or l,25(OH)2D3 [143-145], l,25(OH)2D3 has further proven to be therapeutically effective in animal models of autoimmune thyroiditis [146], allogeneic transplantation [66, 147,148], rat Heymann nephritis [149] and autoimmune prostatitis [80]. Results from l,25(OH)2D3-related studies in animal models are summarized in Table 10.3. 

Chemicals may exacerbate autoimmunity in genetically predisposed animals or in induced animal models (Kammuller et al., 1989a). The rationale behind using autoimmune-prone animal strains for the purpose of studying and predicting the autoim-munogenic potential of chemicals is that, apart from being probably very sensitive for adverse immune effects, exacerbation of disease is considered one of the possibilities by which chemicals may elicit autoimmune phenomena (Pollard et al., 1999). As mentioned also, the Brown Norway rat is a sensitive rat strain for Th2-dependent phenomena, as is the Lewis rat for cyclosporin-induced autoimmunity. 

The immunosuppressive drug cyclosporine A (CSA) has revolutionized transplant medicine. However, CSA induced-nephrotoxicity still represents a major therapeutic challenge. Chronic CSA nephropathy is characterized by a decrease in glomerular filtration rate (GFR), tubular atrophy, interstitial fibrosis and progressive renal dysfunction. It is difficult to delineate the mechanisms of CSA toxicity from clinical data since the majority of clinical experiences with CSA have been in renal transplant recipients. Animal models of CSA nephropathy have brought some insights, how-... 

---