Gene Expression in Biopsies of Acute Rejection and Interstitial Fibrosis/Tubular Atrophy Reveals Highly Shared Mechanisms That Correlate With Worse Long-Term Outcomes.

Interstitial fibrosis and tubular atrophy (IFTA) is found in approximately 25% of 1-year biopsies posttransplant. It is known that IFTA correlates with decreased graft survival when histological evidence of inflammation is present. Identifying the mechanistic etiology of IFTA is important to understanding why long-term graft survival has not changed as expected despite improved immunosuppression and dramatically reduced rates of clinical acute rejection (AR) (Services UDoHaH. http://www.ustransplant.org/annual_reports/current/509a_ki.htm). Gene expression profiles of 234 graft biopsy samples were obtained with matching clinical and outcome data. Eighty-one IFTA biopsies were divided into subphenotypes by degree of histological inflammation: IFTA with AR, IFTA with inflammation, and IFTA without inflammation. Samples with AR (n = 54) and normally functioning transplants (TX; n = 99) were used in comparisons. A novel analysis using gene coexpression networks revealed that all IFTA phenotypes were strongly enriched for dysregulated gene pathways and these were shared with the biopsy profiles of AR, including IFTA samples without histological evidence of inflammation. Thus, by molecular profiling we demonstrate that most IFTA samples have ongoing immune-mediated injury or chronic rejection that is more sensitively detected by gene expression profiling. These molecular biopsy profiles correlated with future graft loss in IFTA samples without inflammation.

Molecular classifiers for acute kidney transplant rejection in peripheral blood by whole genome gene expression profiling.

There are no minimally invasive diagnostic metrics for acute kidney transplant rejection (AR), especially in the setting of the common confounding diagnosis, acute dysfunction with no rejection (ADNR). Thus, though kidney transplant biopsies remain the gold standard, they are invasive, have substantial risks, sampling error issues and significant costs and are not suitable for serial monitoring. Global gene expression profiles of 148 peripheral blood samples from transplant patients with excellent function and normal histology (TX; n = 46), AR (n = 63) and ADNR (n = 39), from two independent cohorts were analyzed with DNA microarrays. We applied a new normalization tool, frozen robust multi-array analysis, particularly suitable for clinical diagnostics, multiple prediction tools to discover, refine and validate robust molecular classifiers and we tested a novel one-by-one analysis strategy to model the real clinical application of this test. Multiple three-way classifier tools identified 200 highest value probesets with sensitivity, specificity, positive predictive value, negative predictive value and area under the curve for the validation cohort ranging from 82% to 100%, 76% to 95%, 76% to 95%, 79% to 100%, 84% to 100% and 0.817 to 0.968, respectively. We conclude that peripheral blood gene expression profiling can be used as a minimally invasive tool to accurately reveal TX, AR and ADNR in the setting of acute kidney transplant dysfunction.

Human cytomegalovirus-associated periodontitis in renal transplant patients.

BACKGROUND: Human cytomegalovirus (HCMV) infection is associated with renal transplant failure. Periodontal pockets may be reservoirs for HCMV replication. OBJECTIVES: This study was done to determine active HCMV replication in saliva and gingival crevicular fluid of renal transplant patients affected by periodontitis. METHODS: HCMV pp67-mRNA amplification was analyzed in oral fluids of 38 transplant recipients at 6 months' posttransplantation. Patients received antiviral therapy until 3 months' posttransplantation. The HCMV-positive cell line VR-977 was the positive control, and oral fluids from healthy volunteers served as the negative control. Periodontitis was diagnosed by clinical examination. Serum HCMV IgG and IgM were analyzed to differentiate recent and latent infection. RESULTS: Prevalence of gingival overgrowth was 68.4%. HCMV gene transcripts were detected in the saliva of 21% and the gingival crevicular fluid of 18% of patients. All patients (100%) with HCMV pp67-mRNA detected in saliva demonstrated clinical manifestations of viral infection, as did 86% of patients with HCMV pp67-mRNA detected in the gingival crevicular fluid. Serum IgM was positive in 7.9% of patients and IgG in 65.8%; however, associations with active mRNA replication were not statistically significant. CONCLUSIONS: Renal transplant patients affected by periodontitis are at risk of viral replication within the periodontal tissues despite antiviral therapy. This study suggests that use of HCMV pp67-mRNA detection in saliva and gingival crevicular fluid provides markers of active viral infection, and evidence for a link between HCMV-associated periodontitis and renal transplant complications.

Incidence of new-onset hypercholesterolemia in renal transplant patients treated with FK506 or cyclosporine.

In this study, we compare cholesterol levels during the first year after renal transplantation in FK506 (Prograf)- and cyclosporine-treated patients matched for cumulative first-year steroid dose and hypercholesterolemia risk factors. All patients had pretransplant cholesterol levels < 200 mg/dl. At 3 months posttransplant, 68% of the cyclosporine-treated patients had at least one cholesterol level greater than 200 mg/dl compared with 30% of the FK506-treated patients (P < 0.05). At the end of the year, 26% of FK506- and 67% of cyclosporine-treated patients remained hypercholesterolemic (P < 0.05). We conclude that cyclosporine has inherently more effect on cholesterol levels than FK506 during the first year after kidney transplantation.

Risks of transplanting kidneys from hepatitis B surface antigen-negative, hepatitis B core antibody-positive donors.

BACKGROUND: As the number of patients on the United States kidney transplant list increases, investigation into the utility of transplanting organs formerly considered marginal or undesirable has intensified. Using kidneys from hepatitis B surface antigen (HBsAg)-positive donors is thought to place recipients at excessive risk of graft failure, morbidity, and mortality. However, the risks of using kidneys from HBsAg-negative but hepatitis B core antibody (HBcAb)-positive donors have not been defined. METHODS: Between 1990 and 1994, our group transplanted 1067 cadaveric kidneys, including 38 from HBsAg(-)/HBcAb(+) donors. Of these 38 kidneys, 27 were transplanted into HBcAb(-) recipients (group 1) and 11 were transplanted into HBcAb(+) recipients (group 2). Group 1 and 2 patients received no hepatitis immunoglobulin therapy after transplantation and received the same immunosuppression and rejection therapies as recipients of kidneys from HBcAb(-) donors. RESULTS: After transplantation, none of the group 1 patients became HBsAg(+), three became hepatitis B surface antibody (HBsAb)-positive, and two became HBcAb(+). Of the group 2 patients, none became newly HBsAg(+) or HBsAb(+). No patient receiving a kidney from an HBsAg(-)/HBcAb(+) donor developed signs or symptoms of clinical hepatitis B. Graft and patient survival rates were similar in both groups and similar to the rates of the 1029 recipients of kidneys from HBcAb(-) donors. CONCLUSIONS: Recipients of kidneys from HBsAg(-)/HBcAb(+) donors are at a small risk of hepatitis B seroconversion but are at no excess risk of graft failure or short-term morbidity or mortality.

Outcome of en bloc and single kidney transplantation from very young cadaveric donors.

BACKGROUND: The optimal use of very young cadaveric kidneys (from donors less than 4 years old) remains controversial. High rates of technical complications and poor functional results compared with adult donor kidneys have been reported. The use of en bloc transplantation to overcome these problems has been advocated, although en bloc transplantation halves the number of potential transplants from very young donors. METHODS: We studied the technical and functional results of 91 transplants from very young donors performed at our institution between 1984 and 1995. This included 59 single and 22 en bloc procedures involving first transplants and 7 single and 3 en bloc procedures involving retransplantation. Individual surgeon preference dictated the use of either the single or en bloc technique. Kidneys smaller than 6 cm tended to be transplanted en bloc, and lighter patients were generally given preference for receiving pediatric kidneys. Patients received sequential cyclosporine-based quadruple immunosuppression. RESULTS: En bloc kidneys had a 1-year and 5-year graft survival of 82% and 70%, respectively. Single kidneys had a 1-year and 5-year graft survival of 64% and 40%. Kidneys that avoided acute rejection episodes and that were transplanted into heavier or male recipients had better long-term survival. Kidneys from donors less than 2 years old did poorly whether transplanted en bloc or singly. Better HLA matching improved short-term, but not long-term, graft survival, whereas cold ischemic time did not have statistically significant association with differences in graft survival. Eleven percent of the transplants had ureteral leaks, but only one kidney was lost. Ten transplants had vascular complications leading to graft loss, whereas two episodes of arterial stenosis were successfully treated with percutaneous angioplasty. CONCLUSIONS: En bloc transplantation optimizes the outcome of transplantation with very young kidneys. We recommend induction therapy and cyclosporine immunosuppression with cyclosporine levels similar to adult target levels to minimize rejection episodes and, thus, improve outcome. These kidneys should be distributed nationally, because better HLA matching is associated with improved short-term graft survival. Our high ureteral leak rate indicates that alternatives to unstented ureteroneocystostomy should be considered.

Parvovirus B19 infection-related complications in renal transplant recipients: treatment with intravenous immunoglobulin.

BACKGROUND: Chronic red cell aplasia can develop in immunocompromised patients including transplant recipients infected with parvovirus B19 (PV B19). Renal involvement with PV B19 infection is not well-recognized. METHODS: We diagnosed erythroid hypoplasia associated with PV B19 infection in three renal transplant recipients; one of them developed de novo collapsing glomerulopathy. These patients were treated with intravenous immunoglobulin (IVIG). RESULTS: In two patients, anemia responded promptly to IVIG therapy. One of them had recurrence of anemia that responded to a second course of IVIG. Despite IVIG treatment, persistent infection with PV B19, recurrent anemia, and de novo collapsing glomerulopathy leading to allograft failure developed in the third patient, who had received the most intense immunosuppression. CONCLUSIONS: These findings indicate that PV B19 infection in transplant recipients can cause chronic red cell aplasia that generally responds to IVIG therapy. In some patients, particularly those who are heavily immunosuppressed, infection may persist despite treatment. As the cellular receptor for PV B19 is expressed in the kidney, persistent infection may result in development of glomerulopathies in these patients.