The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

Calcineurin Inhibitor Nephrotoxicity

Bone metabolism and disease in chronic kidney disease

Mitochondria are semi-autonomous organelles which are endowed with the ability to change their shape (e.g., by elongation, shortening, branching, buckling, swelling) and their location inside a living cell. In addition they may fuse or divide. These dynamics are discussed. Dislocation of mitochondria may result from their interaction with elements of the cytoskeleton, with microtubules in particular, and from processes intrinsic to the mitochondria themselves. Morphological criteria and differences in the fate of some mitochondria argue for the presence of more than one mitochondrial population in some animal cells. Whether these reflect genetic differences remains obscure. Emphasis is laid on the methods for visualizing mitochondria in cells and following their behaviour. Fluorescence methods provide unique possibilities because of their high resolving power and because some of the mitochondria-specific fluorochromes can be used to reveal the membrane potential. Fusion and fission often occur in short time intervals within the same group of mitochondria. At sites of fusion of two mitochondria material of the inner membrane, the matrix compartment seems to accumulate. The original arrangement of the fusion partners is maintained for some minutes. Fission is a dynamic event which, like fusion, in most cases observed in vertebrate cell cultures is not a straight forward process but rather requires several "trials" until the division finally occurs. Regarding fusion and fission hitherto unpublished phase contrast micrographs, and electron micrographs have been included.

Dynamics of mitochondria in living cells: Shape changes, dislocations, fusion, and fission of mitochondria

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general popu- lation, but there are no comprehensive guidelines for the pre- vention of diseases and complications after renal transplanta- tion. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guide- lines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpa- tient screening for and prevention of diseases and complica- tions that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and compli- cations after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that sup- ports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Recommendations for the Outpatient Surveillance of Renal Transplant Recipients

Chronic cyclosporine nephropathy: the Achilles' heel of immunosuppressive therapy.

Morphological patterns in cyclosporine-treated renal transplant recipients.

We carried out a randomized prospective trial to compare OKT3 (5 mg/d, 51 patients) with ATG-Fresenius (ATG-F, 4 mg/kg/d, 53 patients) for induction therapy after renal transplantation, concerning side effects, rejection, and infection incidence within a one year follow-up period. Concomitant immunosuppression included azathioprine/steroids from day 0 and cyclosporine A from day 4. OKT3 patients experienced significantly more and more-severe side effects, particularly pyrexia, headache, and pulmonary fluid overload. One-year graft survival was excellent in the ATG-F group (91%), but only 78% in the OKT3 group (P < 0.05) due to a series of rejections that occurred beyond day 100; patient survival (96% and 92%) was similar in both groups. OKT3-treated patients experienced more biopsy-proven rejections (0.6 +/- 0.1/pt.) than ATG-F patients (0.3 +/- 0.1, P < 0.05), and there was a similar, albeit not significant trend in clinical rejections (OKT3: 1.1 +/- 0.2/pt.; ATG-F: 0.8 +/- 0.1/pt.). Infections were more common in the OKT3 group (OKT3: 3.2 +/- 0.3, ATG-F: 2.0 +/- 0.2, P < 0.05), although this was entirely attributable to "minor" infections. On days 1 through 6, CD3 counts were more profoundly depressed with OKT3 therapy. Beyond day 10, however, CD3 counts were lower in the ATG-F group, as were CD2 counts, CD4 counts, and the CD4/CD8 ratio, suggesting a more prolonged immunosuppressive effect of ATG-F. Sensitization occurred more frequently with OKT3 (31%) than with ATG-F (10%), but was usually irrelevant, except in two patients (one in each group), whose grafts were lost because of immunization against OKT3 and ATG-F, respectively. In conclusion, a 7-day induction therapy with OKT3 does not improve outcome or diminish immunological graft loss when compared with ATG-F, but is associated with more rejections, infections, and side effects. ATG-F appears to be preferable for induction immunosuppression after renal transplantation.

A randomized prospective trial of prophylactic immunosuppression with ATG-fresenius versus OKT3 after renal transplantation

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.1840020616

Demonstration of albumin receptors onisolated human hepatocytes by light and scanning electron microscopy

Osteopenia has been observed to occur frequently after renal transplantation. The present study was undertaken to assess whether an immunosuppressive regimen combining cyclosporine with no or the lowest possible maintenance doses of glucocorticoid may prevent osteopenia after kidney transplantation. Thirty-four patients were prospectively followed for two years. Serial blood drawings were done for determination of serum indices of calcium and bone metabolism and an iliac crest bone biopsy was performed at time of transplantation. A second bone biopsy was done in 20 patients during the second year of observation. Creatinine clearance was 56 +/- 6 ml/min one year and 46 +/- 6 ml/min two years after transplantation. Serum parathyroid hormone levels were elevated in 24 patients at time of grafting, decreased significantly thereafter, but remained above the normal range. Ten patients had low or normal serum parathyroid hormone levels at time of transplantation and showed a significant increase after grafting. Two years after transplantation, the mean cumulative dose of prednisone was 5.9 +/- 0.5 g. After the first six months, 30-40% of the patients were not on maintenance doses of steroids. None of the patients experienced fractures, and cancellous bone volume was within or above the normal range in all repeat bone biopsies. It is of note that metabolic bone abnormalities did not resolve 1-2 years after transplantation despite normalization of serum 1,25 vitamin D levels. The histologic abnormalities at the time were consistent with the bone findings in renal failure suggesting resistance of bone to normal circulating levels of 1,25 vitamin D.

Prevention of cancellous bone loss but persistence of renal bone disease despite normal 1,25 vitamin D levels two years after kidney transplantation.

The extreme lack of renal grafts for transplantation stimulated us to analyze how strict the selection criteria of kidney donors must be. We investigated therefore if preexisting lesions in renal grafts influence initial and late renal function. 147 zero-hour biopsies of 101 donors (mean age 33, from 6-64 years) were examined. By ligh microscopy 38% of biopsies showed no, 44% showed nonspecific and 18% specific lesions. Nonspecific lesions comprised intimal fibrosis of small arteries in 44%, interstitial fibrosis in 8% and an arteriolar hyalinosis in 29%. Out of 102 immunohistologically examined biopsies 74.5% showed nonspecific IgM/C3 deposits in glomeruli and/or arterioles. An age dependent decrease of normal renal biopsies was found which was most evident in donors older than 40 years. Specific findings consisted of glomerulosclerosis (n = 4), glomerulonephritis (n = 11), intravascular coagulation (n = 10) and eclamptic kidney (n = 1). In case of nonspecific immunohistologic findings and in glomerulonephritis rebiopsies showed that antigen deposits usually disappeared within 4 months. Independent of morphologic findings 82% of transplant recipients had a good initial and late renal function. Since donor age, glomerulosclerosis, glomerulonephritis, intravascular coagulation or eclamptic changes seem not to compromise renal function after transplantation a more liberal choice of donors should be considered.

Landmann J

Papers

Morphological patterns in cyclosporine-treated renal transplant recipients.

A randomized prospective trial of prophylactic immunosuppression with ATG-fresenius versus OKT3 after renal transplantation

Demonstration of albumin receptors onisolated human hepatocytes by light and scanning electron microscopy

Prevention of cancellous bone loss but persistence of renal bone disease despite normal 1,25 vitamin D levels two years after kidney transplantation.

Morphologic findings in "zero-hour" biopsies of renal transplants.