The effect of combined rapamycin/cyclosporine on the changes in pro-fibrotic gene expression that occur during the development of allograft vasculopathy in rats, compared with cyclosporine or rapamycin in isolation

On the action of cyclosporine A, rapamycin and tacrolimus on M. avium including subspecies paratuberculosis

Background

Mycobacterium avium subspecies paratuberculosis (MAP) may be zoonotic. Recently the “immuno-modulators” methotrexate, azathioprine and 6-MP and the “anti-inflammatory” 5-ASA have been shown to inhibit MAP growth in vitro. We concluded that their most plausible mechanism of action is as antiMAP antibiotics. The “immunosuppressants” Cyclosporine A, Rapamycin and Tacrolimus (FK 506) treat a variety of “autoimmune” and “inflammatory” diseases. Rapamycin and Tacrolimus are macrolides. We hypothesized that their mode of action may simply be to inhibit MAP growth.

Methodology

The effect on radiometric MAP ¹⁴CO₂ growth kinetics of Cyclosporine A, Rapamycin and Tacrolimus on MAP cultured from humans (Dominic & UCF 4) or ruminants (ATCC 19698 & 303) and M. avium subspecies avium (ATCC 25291 & 101) are presented as “percent decrease in cumulative GI” (%-ΔcGI.)

Principal Findings

The positive control clofazimine has 99%-ΔcGI at 0.5 µg/ml (Dominic). Phthalimide, a negative control has no dose dependent inhibition on any strain. Against MAP there is dose dependent inhibition by the immunosuppressants. Cyclosporine has 97%-ΔcGI by 32 µg/ml (Dominic), Rapamycin has 74%-ΔcGI by 64 µg/ml (UCF 4) and Tacrolimus 43%-ΔcGI by 64 µg/ml (UCF 4)

Conclusions

We show heretofore-undescribed inhibition of MAP growth in vitro by “immunosuppressants;” the cyclic undecapeptide Cyclosporine A, and the macrolides Rapamycin and Tacrolimus. These data are compatible with our thesis that, unknowingly, the medical profession has been treating MAP infections since 1942 when 5-ASA and subsequently azathioprine, 6-MP and methotrexate were introduced in the therapy of some “autoimmune” and “inflammatory” diseases.

Protective effects of sirolimus by attenuating connective tissue growth factor expression in human chronic allograft nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN) remains a great challenge for the transplant clinician. The introduction of sirolimus (RAPA) with cyclosporine (CsA) reduction maybe shed new light to improve graft survival. The aim of this study was to investigate the overall effects of sirolimus conversion on biopsy-proven CAN.

METHODS

One hundred and ten renal transplant recipients with biopsy-proven CAN were randomized into two groups: 54 for CsA reduction and 56 for sirolimus conversion treatment. After 24-month follow-up, the outcome variables included graft function and survival as well as CAN Banff grading and intrarenal expression of connective tissue growth factor (CTGF) via repeated biopsy.

RESULTS

Graft function and survival rate were significantly better in the RAPA group. CAN grading worsened in the CsA group, whereas they were stable in the RAPA group. There was weak expression in the RAPA group but significant, increased expression of CTGF in glomeruli and interstitial area in the CSA group (P < .01) both by immunohistochemical staining or real-time polymerase chain reaction detection.

CONCLUSION

Sirolimus conversion provided a beneficial strategy to improve long-term graft survival in CAN. Attenuation of renal CTGF expression may be one of its antifibrotic and antiproliferation effects.

Everolimus inhibits glomerular endothelial cell proliferation and VEGF, but not long-term recovery in experimental thrombotic microangiopathy

BACKGROUND

Everolimus is a potent immunosuppressant used in renal transplant therapy, but its effects on renal endothelial cell regeneration after injury are unknown. The effects of an everolimus therapy were investigated in a model of renal thrombotic microangiopathy (TMA) with specific endothelial cell (EC) injury in the rat in vivo as well as in glomerular ECs in vitro.

METHODS

During the early regenerative phase (day 3) of the renal microvascular injury model in vivo, everolimus inhibited glomerular EC proliferation by up to 60% compared with vehicle-treated rats, whereas apoptosis was not different in these groups. This decreased EC proliferation was associated with an enhanced deposition of fibrin in everolimus treated animals on day 3. In cultured glomerular endothelial cells, everolimus effectively and dose dependently inhibited cellular proliferation. This anti-proliferative effect was associated with a reduced phosphorylation of the p70S6 kinase and reduction of the pro-angiogenic factor VEGF in glomeruli in vivo and in cultured podocytes in vitro.

RESULTS

Despite the prolonged EC repair and in contrast to the anti-Thy1 nephritis model, everolimus therapy did not disturb the long-term repair reaction in this thrombotic microangiopathy model.

CONCLUSION

Everolimus is anti-proliferative for glomerular EC in vitro and in vivo and does not seem to have detrimental long-term effects in experimental renal TMA, when only the glomerular endothelium, but not the mesangium is severely injured.