Chronic rejection and graft arteriosclerosis: 4 years after the Alexis Carrel proposal on diagnostic criteria

Chronic allograft nephropathy--biopsy findings and outcome

BACKGROUND

Chronic allograft nephropathy (CAN) is a composite term for various types of damage to a kidney transplant. We wanted to analyse its components in relation to baseline biopsy findings, transplant function, and outcome.

METHODS

Among renal transplantations performed from 1985 to 1997, 156 were identified where allograft biopsies had been obtained on clinical indication 6 months after transplantation or later, baseline biopsies were available in each case and the patient's original disease was known. Time after transplantation was median 2.2 years (range 0.5-13). The biopsies were reviewed and the Banff 1997 CAN score obtained.

RESULTS

All but one late biopsy showed some CAN grade, 48% grade II, and 7.5% grade III. Acute tubulointerstitial rejection was seen in 9% but vascular rejection in only 3%. Arterial wall thickening was present in 66% of the late biopsies, correlated with donor age and its presence at baseline but also with time after transplantation. The Banff CAN score and serum creatinine level were both independent predictors of further graft survival, relative risk 0.35 (confidence interval 0.15-0.82, P=0.015) for CAN grade I vs III and 0.30 (0.14-0.67, P=0.003) for serum creatinine <170 vs >250 micromol/l. Presence of arterial wall thickening had no prognostic impact.

CONCLUSION

The CAN grade is predictive of further graft survival independently of the serum creatinine level. Interstitial fibrosis and tubular atrophy are more prominent features of chronic graft damage than vascular rejection. Unspecific arterial wall thickening is partly dependent on baseline conditions and lacks prognostic impact in this late stage.

Chronic allograft failure in human renal transplantation: a multivariate risk factor analysis

OBJECTIVE

To identify potential risk factors for the development of chronic renal allograft failure.

SUMMARY BACKGROUND DATA

Chronic allograft failure (CAF) is the leading cause of late graft loss in renal transplantation. The authors studied the risk factors for the development of CAF in a single center during a period in which a consistent baseline immunosuppression regimen (cyclosporine, azathioprine, and prednisolone) was used.

METHODS

Data from the Oxford Transplant Center Database were assessed on 862 renal allografts during a 10-year period. Risk factors were identified using multivariate logistic regression analysis.

RESULTS

Biopsy-proven CAF occurred in 77 patients (9.2%) in the entire group. Multivariate risk factor analysis revealed that early and late acute rejection episodes, proteinuria, and serum triglycerides were significant factors. Acute rejection after 3 months was more important than early acute rejection. Serum triglyceride level and proteinuria at 1 year were both elevated in the CAF group. Male sex provided a protective effect. Serum creatinine levels at 6 months after the transplant were not predictive of the risk of developing CAF.

CONCLUSIONS

These results from the largest single-center review to date suggest that both antigen-dependent and -independent factors are involved in the pathogenesis of CAF. Acute rejection at all time points has a significant impact on the development of CAF.

Adhesion molecule polymorphisms in chronic renal allograft failure

BACKGROUND

Chronic allograft failure (CAF) is a major cause of late graft loss in renal transplantation. Up-regulation of adhesion molecules has been demonstrated in renal allograft biopsies during both acute and chronic rejection, and these molecules are known to regulate leukocyte migration into the graft.

METHODS

A single-center retrospective study was performed between 1985 and 1996 on renal transplant recipients who developed CAF. Genotyping was performed for five polymorphisms in intercellular adhesion molecule-1 (ICAM-1), E-selectin, and L-selectin. Frequency data for the polymorphisms in the CAF group (N = 62) and their matched donors, where available (N = 33), were compared with a group of recipients with graft survival of more than 10 years (N = 110) and a group of United Kingdom (UK) controls (N = 101).

RESULTS

A variant allele in exon 4 of ICAM-1 (R241) was more common in the CAF recipients compared with both long-term survivors and UK controls (19.4 vs. 10.0 and 9.4%, P = 0.015 and 0.025). In addition, stratification by time to graft failure caused by CAF revealed more rapid failure in the presence of another ICAM-1 variant in the recipient (E469) in exon 6 (P = 0.033).

CONCLUSIONS

ICAM-1 polymorphisms may represent a predetermined genetic risk factor for CAF. The polymorphism in exon 4 is in the Mac-1 binding site, and that in exon 6 is in the fifth immunoglobulin-like domain. Potential mechanisms of action of ICAM-1 variants in CAF include an alteration of activity as an adhesion molecule, altered costimulation, or a minor histocompatibility antigen.