Immunosuppression withdrawal in living-donor renal transplant recipients following induction with antithymocyte globulin and rituximab: Results of a prospective clinical trial

Durable tolerance in kidney transplant recipients remains an important but elusive goal. We hypothesized that adding B cell depletion to T cell depletion would generate an immune milieu postreconstitution dominated by immature transitional B cells, favoring tolerance. The Immune Tolerance Network ITN039ST Research Study of ATG and Rituximab in Renal Transplantation was a prospective multicenter pilot study of live donor kidney transplant recipients who received induction with rabbit antithymocyte globulin and rituximab and initiated immunosuppression (IS) withdrawal (ISW) at 26 weeks. The primary endpoint was freedom from rejection at 52 weeks post-ISW. Six of the 10 subjects successfully completed ISW. Of these 6 subjects, 4 restarted immunosuppressive medications due to acute rejection or recurrent disease, 1 remains IS-free for over 9 years, and 1 was lost to follow-up after being IS-free for 42 weeks. There were no cases of patient or graft loss. CD19+ B cell frequencies returned to predepletion levels by 26 weeks posttransplant; immunoglobulin D+CD27--naïve B cells predominated. In contrast, memory cells dominated the repopulation of the T cell compartment. A regimen of combined B and T cell depletion did not generate the tolerogenic B cell profile observed in preclinical studies and did not lead to durable tolerance in the majority of kidney transplant recipients.

Complications of rabbit anti-thymocyte globulin induction immunosuppression in HIV-infected kidney transplant recipients

Background

Kidney transplantation in HIV-infected individuals with end-stage kidney disease is associated with improved survival compared to dialysis. Rabbit anti-thymocyte globulin (rATG) induction in HIV-infected kidney transplant recipients has been associated with a lower risk of acute rejection, but data on the rates of de novo malignancy and BK viremia in these patients is lacking.

Methods

We performed a single-center retrospective cohort study of adult HIV-infected individuals who underwent kidney transplantation with rATG induction between January 2006 and December 2016. The primary outcome was the development of de novo malignancy. Secondary outcomes included the development of BK viremia, infections requiring hospitalization, HIV progression, biopsy-proven acute rejection, and patient and allograft survival.

Results

Twenty-seven HIV-infected individuals with end-stage kidney disease received deceased (n=23) or living (n=4) donor kidney transplants. The cumulative rate of malignancy at five years was 29%, of whom 29% died because of advanced malignancy. BK viremia was detected in six participants (22%), of whom one had biopsy-proven BK virus-associated nephropathy and all of whom cleared the BK viremia. Five-year acute rejection rates, patient survival and death-censored allograft survival were 17%, 85% and 80% respectively.

Conclusion

rATG induction in HIV-infected kidney transplant recipients was associated with a low risk of acute rejection, but a potentially higher risk of de novo malignancies and BK viremia in this cohort. Screening strategies to closely monitor for BK virus infection and malignancy post-transplantation may improve outcomes in HIV-infected kidney transplant recipients receiving rATG induction.

Validation of a noninvasive prognostic signature for allograft failure following BK virus associated nephropathy

Identifying kidney transplant recipients at risk for graft failure following BK virus nephropathy (BKVN) may allow personalization of therapy. We have reported that a noninvasive composite signature of urinary cell level of plasminogen activator inhibitor-1(PAI-1) mRNA and serum creatinine level, measured at the time of BKVN diagnosis, is prognostic of graft failure. In this investigation, we determined whether the composite signature is prognostic of graft failure in an independent cohort of 25 patients with BKVN. Of the 25 patients, 8 developed graft failure and 17 did not. We measured urinary cell levels of PAI-1 mRNA, 18S rRNA, and BKV VP1 mRNA at the time of BKVN diagnosis and evaluated clinical parameters including Banff pathology scores, acute rejection, and graft function. The area under the receiver operating characteristic curve for the noninvasive composite signature was 0.95 (P < .001) for prognosticating graft failure. The previously reported threshold of -0.858 predicted graft failure with a sensitivity of 75% and a specificity of 94%. Our current study validates the use of composite signature and the threshold of -0.858 to identify those at risk for graft failure following BKVN diagnosis, and supports future studies utilizing the composite signature score to personalize treatment of BKVN.

Kidney allograft recipients, immunosuppression, and coronavirus disease-2019: a report of consecutive cases from a New York City transplant center

BACKGROUND

Kidney graft recipients receiving immunosuppressive therapy may be at heightened risk for coronavirus disease 2019 (Covid-19) and adverse outcomes. It is therefore important to characterize the clinical course and outcome of Covid-19 in this population and identify safe therapeutic strategies.

METHODS

We performed a retrospective chart review of 73 adult kidney graft recipients evaluated for Covid-19 from 13 March to 20 April 2020. Primary outcomes included recovery from symptoms, acute kidney injury, graft failure and case fatality rate.

RESULTS

Of the 73 patients screened, 54 tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-39 with moderate to severe symptoms requiring hospital admission and 15 with mild symptoms managed in the ambulatory setting. Hospitalized patients were more likely to be male, of Hispanic ethnicity and to have cardiovascular disease. In the hospitalized group, tacrolimus dosage was reduced in 46% of patients and mycophenolate mofetil (MMF) therapy was stopped in 61% of patients. None of the ambulatory patients had tacrolimus reduction or discontinuation of MMF. Azithromycin or doxycycline was prescribed at a similar rate among hospitalized and ambulatory patients (38% versus 40%). Hydroxychloroquine was prescribed in 79% of hospitalized patients. Graft failure requiring hemodialysis occurred in 3 of 39 hospitalized patients (8%) and 7 patients died, resulting in a case fatality rate of 13% among Covid-19-positive patients and 18% among hospitalized Covid-19-positive patients.

CONCLUSIONS

Data from our study suggest that a strategy of systematic triage to outpatient or inpatient care, early management of concurrent bacterial infections and judicious adjustment of immunosuppressive drugs rather than cessation is feasible in kidney transplant recipients with Covid-19.

Kidney allograft failure in the steroid-free immunosuppression era: A matched case-control study

We studied the causes and predictors of death-censored kidney allograft failure among 1670 kidney recipients transplanted at our center in the corticosteroid-free maintenance immunosuppression era. As of January 1, 2012, we identified 137 recipients with allograft failure; 130 of them (cases) were matched 1-1 for recipient age, calendar year of transplant, and donor type with 130 recipients with functioning grafts (controls). Median time to allograft failure was 29 months (interquartile range: 18-51). Physician-validated and biopsy-confirmed categories of allograft failure were as follows: acute rejection (21%), glomerular disease (19%), transplant glomerulopathy (13%), interstitial fibrosis tubular atrophy (10%), and polyomavirus-associated nephropathy (7%). Graft failures were attributed to medical conditions in 21% and remained unresolved in 9%. Donor race, donor age, human leukocyte antigen mismatches, serum creatinine, urinary protein, acute cellular rejection, acute antibody-mediated rejection, BK viremia, and CMV viremia were associated with allograft failure. Independent predictors of allograft failure were acute cellular rejection (odds ratio: 18.31, 95% confidence interval: 5.28-63.45) and urine protein ≥1 g/d within the first year post-transplantation (5.85, 2.37-14.45). Serum creatinine ≤1.5 mg/dL within the first year post-transplantation reduced the odds (0.29, 0.13-0.64) of allograft failure. Our study has identified modifiable risk factors to reduce the burden of allograft failure.

Long term follow up of kidney donors with asymptomatic renal stones

Patients with asymptomatic kidney stones have a high rate of progression to becoming symptomatic kidney stones when followed for several years. Small kidney stones are often found incidentally on imaging when evaluating patients for kidney donation, and there is a concern that after nephrectomy, the donor may become symptomatic and incur damage to the remaining kidney. We reviewed kidney donors at our institution with asymptomatic stones and surveyed them several years after donation to see if the stones became clinically active.

Bortezomib for Reduction of Proteinuria in IgA Nephropathy

Introduction

IgA nephropathy is the most common glomerulonephritis in the world. We conducted a pilot trial (NCT01103778) to test the effect of bortezomib in patients with IgA nephropathy and significant proteinuria.

Methods

We treated 8 consecutive subjects from July 2011 until March 2016 with 4 doses of bortezomib. All subjects had biopsy-proven IgA nephropathy and proteinuria of greater than 1 g per day. They were given 4 doses of bortezomib i.v. at 1.3 mg/m² of body surface area per dose. Changes in proteinuria and renal function were followed for 1 year after enrollment. The primary endpoint was full remission defined as proteinuria of less than 300 mg per day.

Results

All 8 subjects received and tolerated 4 doses of bortezomib over a 2-week period during enrollment. The median baseline daily proteinuria was 2.46 g (interquartile range: 2.29–3.16 g). At 1-year follow-up, 3 subjects (38%) had achieved the primary endpoint. The 3 subjects who had complete remission had Oxford classification T scores of 0 before enrollment. Of the remaining 5 subjects, 1 was lost to follow-up within 1 month of enrollment and 4 (50%) did not have any response or had progression of disease.

Conclusion

Proteasome inhibition by bortezomib may reduce significant proteinuria in select cases of IgA nephropathy. Subjects who responded to bortezomib had Oxford classification T score of 0 and normal renal function.

Differences in Attitudes Toward Immunosuppressant Therapy in a Multi-ethnic Sample of Kidney Transplant Recipients

Barriers for renal transplant patients to immunosuppressant medication adherence are poorly understood, despite the high rate and toll of non-adherence. We sought to assess factors that contribute to barriers to immunosuppressive medication adherence in an ethnically diverse sample of 312 renal transplant patients recruited from three transplant centers across New York City. Transplant patients who were at least 6 months post-transplant completed questionnaires while waiting for their medical appointment. Ethnic differences were observed on barriers to immunosuppressant adherence. Black and Hispanic participants reported significantly more barriers to adherence compared to Caucasian participants. Differences in perception about the potential harm and necessity of immunosuppressant medications also were present. Using hierarchical multiple regression, age and income were significant predictors of reported barriers to adherence, even while controlling for ethnicity. The most robust predictor of reported barriers was the perception of the medication cost-benefit differential, i.e., the balance between concerns about immunosuppressant medications and their perceived helpfulness (B = - 0.5, p < .001), indicating that varying beliefs about the medication's necessity and utility rather than ethnicity explain the differences in barriers to medication adherence. Future interventions targeting non-adherence should aim to reduce the barriers to adherence by addressing perceived risks and benefits of taking immunosuppressant medication.

In-Hospital Cardiovascular Complications After Pancreas Transplantation in the United States from 2003 to 2012

Large database studies detailing the risk of perioperative cardiovascular complications after pancreas transplant has been limited, perhaps because these outcomes are not captured by transplant registries. Greater data on the incidence and risks of such outcomes could provide additional insight for referring physicians and inform potential recipients of their risk. We performed a serial, cross-sectional analysis of the National Inpatient Sample, the largest publicly available inpatient database in the United States, to assess for the risk of cardiovascular complications after pancreas transplants in the United States from 2003 to 2012 (n = 13,399). Using multivariable logistic regression models, the risk of cardiovascular outcomes after simultaneous pancreas-kidney transplants (SPK) was compared with solitary pancreas transplants (pancreas after kidney and pancreas transplant alone [PAK + PTA]). The unadjusted prevalence of in-hospital cardiovascular complications was higher in SPK than PAK + PTA (5.5% vs 3.7%, p <0.001). After multivariable adjustment, SPK remained associated with significantly higher odds of any cardiovascular complication (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.21 to 1.80, p = 0.01), and particularly stroke (OR 13.41, 95% CI 4.78 to 37.63, p <0.001), compared with PAK + PTA. However, there was no difference in perioperative mortality (OR 0.78, 95% CI 0.54 to 1.12, p = 0.18). In conclusion, these findings highlight the association between uremia and stroke in pancreas transplant patients, as well as the need for improved preoperative cardiac risk assessment and perioperative management, especially in those who underwent SPK.

Development and validation of a prognostic index for allograft outcome in kidney recipients with transplant glomerulopathy

We studied 92 patients with transplant glomerulopathy to develop a prognostic index based on the risk factors for allograft failure within five years of diagnosis (Development cohort). During 60 months (median) follow up, 64 patients developed allograft failure. A chronic-inflammation score generated by combining Banff ci, ct and ti scores, serum creatinine and proteinuria at biopsy, were independent risk factors for allograft failure. Based on the Cox model, we developed a prognostic index and classified patients into risk groups. Compared to the low risk group (median allograft survival over 60 months from diagnosis), patients in the medium risk group had a hazard ratio of 2.83 (median survival 25 months), while those in the high risk group had a hazard ratio of 5.96 (median survival 3.7 months). We next evaluated the performance of the prognostic index in an independent external cohort of 47 patients with transplant glomerulopathy (Validation cohort). The hazard ratios were 2.18 (median survival 19 months) and 16.27 (median survival 1.6 months), respectively, for patients in the medium and high risk groups, compared to the low risk group (median survival 47 months). Our prognostic index model did well in measures of discrimination and calibration. Thus, risk stratification of transplant glomerulopathy based on our prognostic index may provide informative insight for both the patient and physician regarding prognosis and treatment.

Concomitance of IgA nephropathy and diabetic nephropathy in a kidney allograft: case report and review of the literature

Whereas diabetic nephropathy is the most common cause of end-stage renal disease (ESRD), IgA nephropathy is the most common glomerulonephritis in the world. We report a case of a kidney transplant recipient whose native renal disease was presumptive diabetic nephropathy. Five years after transplantation, the patient developed proteinuria, hematuria, and allograft dysfunction. Transplant biopsy revealed IgA nephropathy superimposed on diabetic nephropathy.

Alginate encapsulant incorporating CXCL12 supports long-term allo- and xenoislet transplantation without systemic immune suppression

Islet transplantation represents a potentially curative approach for individuals with Type I Diabetes. The requirement for systemic immune suppression to control immune-mediated rejection of transplanted islets and the limited human islet supply represent significant roadblocks to progress for this approach. Islet microencapsulation in alginate offers limited protection in the absence of systemic immunosuppression, but does not support long-term islet survival. The chemokine, CXCL12, can repel effector T cells while recruiting immune-suppressive regulatory T cells (Tregs) to an anatomic site while providing a prosurvival signal for beta-cells. We proposed that coating or encapsulating donor islets with CXCL12 would induce local immune-isolation and protect and support the function of an allo- or xenograft without systemic immune suppression. This study investigated the effect of alginate microcapsules incorporating CXCL12 on islet function. Islet transplantation was performed in murine models of insulin-dependent diabetes. Coating of islets with CXCL12 or microencapsulation of islets with alginate incorporating the chemokine, resulted in long-term allo- and xenoislet survival and function, as well as a selective increase in intragraft Tregs. These data support the use of CXCL12 as a coating or a component of an alginate encapsulant to induce sustained local immune-isolation for allo- or xenoislet transplantation without systemic immunosuppression.

Urinary cell mRNA profiles and differential diagnosis of acute kidney graft dysfunction

Noninvasive tests to differentiate the basis for acute dysfunction of the kidney allograft are preferable to invasive allograft biopsies. We measured absolute levels of 26 prespecified mRNAs in urine samples collected from kidney graft recipients at the time of for-cause biopsy for acute allograft dysfunction and investigated whether differential diagnosis of acute graft dysfunction is feasible using urinary cell mRNA profiles. We profiled 52 urine samples from 52 patients with biopsy specimens indicating acute rejection (26 acute T cell-mediated rejection and 26 acute antibody-mediated rejection) and 32 urine samples from 32 patients with acute tubular injury without acute rejection. A stepwise quadratic discriminant analysis of mRNA measures identified a linear combination of mRNAs for CD3ε, CD105, TLR4, CD14, complement factor B, and vimentin that distinguishes acute rejection from acute tubular injury; 10-fold cross-validation of the six-gene signature yielded an estimate of the area under the curve of 0.92 (95% confidence interval, 0.86 to 0.98). In a decision analysis, the six-gene signature yielded the highest net benefit across a range of reasonable threshold probabilities for biopsy. Next, among patients diagnosed with acute rejection, a similar statistical approach identified a linear combination of mRNAs for CD3ε, CD105, CD14, CD46, and 18S rRNA that distinguishes T cell-mediated rejection from antibody-mediated rejection, with a cross-validated estimate of the area under the curve of 0.81 (95% confidence interval, 0.68 to 0.93). Incorporation of these urinary cell mRNA signatures in clinical decisions may reduce the number of biopsies in patients with acute dysfunction of the kidney allograft.

Treating IgA nephropathy: quid novi?

IgA nephropathy is a common autoimmune renal disease resulting in kidney failure for patients with significant proteinuria. The therapeutic options are limited including non-specific treatment to reduce proteinuria accomplished by renin-angiotensin blockade. Strategies to control intrarenal inflammation include the administration of fish oil and for severe disease the use of immunosuppressive agents such as cyclophosphamide, glucocorticosteroids, and mycophenolate mofetil. In light of the limited option, there is an unmet need for novel therapeutic intervention in patients with progressive disease. Herein, we review the evidence for existing treatment choices and explore new immunopharmacologic agents being investigated for IgA nephropathy.

Bortezomib therapy for nephrotic syndrome due to idiopathic membranous nephropathy

Idiopathic membranous nephropathy is a common cause of nephrotic syndrome in adults. The nephrotic syndrome due to idiopathic membranous nephropathy is often resistant to glucocorticosteroids and requires an alkylating agent such as chlorambucil or cyclophosphamide to induce remission. Recent studies illustrate that antibodies against the autoantigen M-type phospholipase A2 receptor contribute to a vast majority but not all cases of idiopathic membranous nephropathy. Herein, we report a patient with nephrotic syndrome due to membranous nephropathy that was resistant to 6 months of therapy with ramipril and high-dose glucocorticosteroids but responded to a single cycle of bortezomib infusion.

Immunosuppressive drug therapy

The first successful kidney transplantation between monozygotic identical twins did not require any immunosuppressive drugs. Clinical application of azathioprine and glucocorticosteroids allowed the transfer of organs between genetically disparate donors and recipients. Transplantation is now the standard of care, a life-saving procedure for patients with failed organs. Progress in our understanding of the immunobiology of rejection has been translated to the development of immunosuppressive agents targeting T cells, B cells, plasma cells, costimulatory signals, complement products, and antidonor antibodies. Modern immunopharmacologic interventions have contributed to the clinical success observed following transplantation but challenges remain in personalizing immunosuppressive therapy.

Excellent outcomes with expanded criteria donor kidneys: the role of the recipient's age

At the present time, the number of deceased donor kidney transplants performed annually has remained unchanged for 4 years. Desire for standard criteria donor (SCD) kidneys by recipients, coupled with high discard rates of donor kidneys, contributes to a lack of procedures being performed. A subgroup of recipients, those under age 50, may fare as well with an expanded criteria donor (ECD) allograft as those who receive an SCD kidney. The use of ECD allografts in recipients over 50 years of age, while projected to have poorer allograft survival than that produced with an SCD graft, still results in better recipient survival than patients who have elected to remain on dialysis.

Pancreas transplantation considering the spectrum of body mass indices

BACKGROUND

In kidney, liver, heart, and lung transplantation, extremes of body mass index (BMI) have been reported to influence post-operative outcomes and even survival. Given the limited data in pancreas transplantation, we sought to elucidate the influence of BMI on outcomes.

METHODS

We reviewed 139 consecutive pancreas transplants performed at our institution and divided them into four categories based on BMI: underweight (≤18.5 kg/m(2)), normal (18.6-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), and obese (≥30 kg/m(2)). Parameters analyzed included post-operative complications, early graft loss, one-yr acute rejection rate (AR), non-surgical infections, and survival.

RESULTS

Demographic data were similar between the groups. Compared with normal, only obese patients trended toward more post-operative complications (p = 0.06). Underweight and obese patients had significantly more post-operative infectious complications than normal (p = 0.0005 and p = 0.03, respectively). Obese patients had more complications requiring percutaneous drainage compared with normal (p = 0.03). Overweight and obese patients had significantly more complications requiring re-laparotomy (p = 0.03 and p = 0.048, respectively). Early graft loss, AR, non-surgical infections, and patient and graft survival rates were not different between normal and underweight, overweight, or obese patients (p > 0.05).

CONCLUSIONS

Extremes of BMI were associated with increased morbidity. Donors and recipients should be carefully selected to maximize potential for successful outcomes.

An uncommon glomerular disease in an HIV patient: value of renal biopsy and review of the literature

Renal disease is not uncommon in those infected with HIV. The most common manifestation of HIV in the kidney is HIV-associated nephropathy (HIVAN). Other HIV- and non-HIV-related causes have been described in the literature. Immunotactoid glomerulonephritis (ITG) is a rare disorder found in 0.06% of renal biopsies characterized by organized tubular immune complex deposits, observed more often in Caucasians. ITG tends to occur in an older age group and in some patients has been associated with a hemopoietic malignancy. In this report, we describe a case of ITG occurring in an HIV-positive, hepatitis C (HCV)- and hepatitis B (HBV)-negative female, who presented with microscopic hematuria and proteinuria. A percutaneous kidney biopsy showed diffuse membranous glomerulopathy, with mild mesangial proliferation and segmental sclerosing lesions containing mainly IgG, Kappa- and C3-positive deposits. Electron microscopy revealed diffuse subepithelial tubular deposits diagnostic of ITG. Out of 5 reported HIV-positive cases and ITG in the literature, 3 were HCV+, 2 were Caucasian and 3 were African-American (AA) without detectable hematologic malignancy. We report another case of ITG in an HCV- and HBV-negative, AA female.

Use of bortezomib for prevention and treatment of rejection in sensitized patients

We report 2 cases of sensitized patients who were successfully treated with bortezomib therapy resulting in reduction of donor-specific antibodies (DSA). Our cases illustrate the synergistic effects of combination therapy that includes bortezomib on prevention and treatment of AMR in highly sensitized patients. Moving forward, long-term data on sensitized patients treated with bortezomib are needed to fully evaluate the impact of this therapy.

Outcome of kidney transplantation using expanded criteria donors and donation after cardiac death kidneys: realities and costs

Expanded criteria donors (ECDs) and donation after cardiac death (DCD) provide more kidneys in the donor pool. However, the financial impact and the long-term benefits of these kidneys have been questioned. From 1998 to 2005, we performed 271 deceased donor kidney transplants into adult recipients. There were 163 (60.1%) SCDs, 44 (16.2%) ECDs, 53 (19.6%) DCDs and 11 (4.1%) ECD/DCDs. The mean follow-up was 50 months. ECD and DCD kidneys had a significantly higher incidence of delayed graft function, longer time to reach serum creatinine below 3 (mg/dL), longer length of stay and more readmissions compared to SCDs. The hospital charge was also higher for ECD, ECD/DCD and DCD kidneys compared to SCDs, primarily due to the longer length of stay and increased requirement for dialysis (70,030 dollars, 72,438 dollars, 72,789 dollars and 47,462 dollars, respectively, p < 0.001). Early graft survival rates were comparable among all groups. However, after a mean follow-up of 50 months, graft survival was significantly less in the ECD group compared to other groups. Although our observations support the utilization of ECD and DCD kidneys, these transplants are associated with increased costs and resource utilization. Revised reimbursement guidelines will be required for centers that utilize these organs.

Messenger RNA for FOXP3 in the urine of renal-allograft recipients

BACKGROUND

The outcome of renal transplantation after an episode of acute rejection is difficult to predict, even with an allograft biopsy.

METHODS

We studied urine specimens from 36 subjects with acute rejection, 18 subjects with chronic allograft nephropathy, and 29 subjects with normal biopsy results. Levels of messenger RNA (mRNA) for FOXP3, a specification and functional factor for regulatory T lymphocytes, and mRNA for CD25, CD3epsilon, perforin, and 18S ribosomal RNA (rRNA) were measured with a kinetic, quantitative polymerase-chain-reaction assay. We examined associations of mRNA levels with acute rejection, rejection reversal, and graft failure.

RESULTS

The log-transformed mean (+/-SE) ratio of FOXP3 mRNA copies to 18S ribosomal RNA copies was higher in urine from the group with acute rejection (3.8+/-0.5) than in the group with chronic allograft nephropathy (1.3+/-0.7) or the group with normal biopsy results (1.6+/-0.4) (P<0.001 by the Kruskal-Wallis test). FOXP3 mRNA levels were inversely correlated with serum creatinine levels measured at the time of biopsy in the acute-rejection group (Spearman's correlation coefficient = -0.38, P=0.02) but not in the group with chronic allograft nephropathy or the group with normal biopsy results. Analyses of receiver-operating-characteristic curves demonstrated that reversal of acute rejection can be predicted with 90 percent sensitivity and 73 percent specificity with use of the optimal identified cutoff for FOXP3 mRNA of 3.46 (P=0.001). FOXP3 mRNA levels identified subjects at risk for graft failure within six months after the incident episode of acute rejection (relative risk for the lowest third of FOXP3 mRNA levels, 6; P=0.02). None of the other mRNA levels were predictive of reversal of acute rejection or graft failure.

CONCLUSIONS

Measurement of FOXP3 mRNA in urine may offer a noninvasive means of improving the prediction of outcome of acute rejection of renal transplants.

Noninvasive detection of renal allograft inflammation by measurements of mRNA for IP-10 and CXCR3 in urine

BACKGROUND

We explored the hypothesis that measurements of mRNA encoding interferon-inducible protein-10 (IP-10) or the chemokine receptor CXCR3 in urinary cells offer a noninvasive means of elucidating cellular traffic causing acute rejection of human renal allografts.

METHODS

We obtained 63 urine specimens from 58 renal allograft recipients who underwent 63 allograft biopsies to resolve the basis for graft dysfunction, and 27 additional urine samples from 24 other patients with stable allograft function. Twenty-seven of the 63 biopsies were classified as acute rejection, 20 as other, and 16 as chronic allograft nephropathy. We measured the levels of transcripts for IP-10 and CXCR3, and a constitutively expressed gene 18S rRNA in the urine specimens and correlated transcript levels with renal allograft diagnosis.

RESULTS

mRNA levels of IP-10 (P < 0.0001) or CXCR3 (P < 0.0001) but not the levels of 18S rRNA (P= 0.56) predicted intragraft cellular traffic causing acute rejection. Receiver-operating characteristic curve analysis demonstrated that acute rejection can be predicted with a sensitivity of 100% and a specificity of 78% using the (log-transformed) cutoff value of 9.11 copies of IP-10, and with a sensitivity of 63% and a specificity of 83% using the cutoff value of 11.59 copies of CXCR3. Immunohistologic analysis of allograft biopsies showed exuberant expression of IP-10 and CXCR3 during acute rejection whereas both were absent in grafts with stable function.

CONCLUSION

Our investigation demonstrates that intragraft cellular events associated with acute rejection of human renal allografts can be noninvasively identified by measurements of mRNA for IP-10 and CXCR3 in urinary cells.

Noninvasive diagnosis of acute rejection of solid organ transplants

Accurate diagnosis of acute rejection remains a formidable challenge in organ transplantation. The current gold standard diagnostic test for acute rejection is histological examination of the transplanted organ. However, biopsy procedures are invasive and complications occur. Furthermore, sampling errors may bias the histological diagnosis. Not uncommonly, empiric anti-rejection therapy has to be provided prior to the availability of a confirmatory histological report. Thus, there is an urgent need for specific and sensitive noninvasive biomarkers of acute rejection. Herein, we review noninvasive strategies for the diagnosis of acute rejection of solid organ transplants.

Molecular signatures of urinary cells distinguish acute rejection of renal allografts from urinary tract infection

Acute rejection (AR) and urinary tract infection (UTI) continue to plague renal transplantation. We tested the hypotheses that UTI does not increase granzyme B mRNA levels in urinary cells, and that the levels distinguish AR from UTI. We measured the levels of granzyme B mRNA in 15 urine specimens from renal allograft recipients with UTI, 29 specimens from patients with AR but without UTI, and 14 specimens from patients without AR and without UTI. We also measured transcript levels in urine specimens from 41 nontransplant individuals, 11 with UTI and 30 without UTI. UTI did not increase granzyme B mRNA levels. Granzyme B mRNA levels were lower in renal allograft recipients with UTI compared with those with AR (P<0.0001). We conclude that bacterial UTI is unlikely to confound AR diagnosis made by measurement of granzyme B mRNA levels in urinary cells.

Serine proteinase inhibitor-9, an endogenous blocker of granzyme B/perforin lytic pathway, is hyperexpressed during acute rejection of renal allografts

BACKGROUND

Serine proteinase inhibitor (PI)-9 with a reactive center P1 (Glu)-P1' is a natural antagonist of granzyme B and is expressed in high levels in cytotoxic T lymphocytes (CTL). In view of the role of CTL in acute rejection, we explored the hypothesis that PI-9 would be hyperexpressed during acute rejection. Because PI-9 can protect CTL from its own fatal arsenal and potentially enhance the vitality of CTL, we examined whether PI-9 levels correlate with the severity of rejection as well as predict subsequent graft function.

METHODS

We obtained 95 urine specimens from 87 renal allograft recipients. RNA was isolated from the urinary cells and mRNA encoding PI-9, granzyme B, or perforin and a constitutively expressed 18S rRNA was measured with the use of real-time quantitative polymerase chain reaction assay, and the level of expression was correlated with allograft status.

RESULTS

The levels of PI-9 (P=0.001), granzyme B (P<0.0001), and perforin mRNAs (P<0.0001), but not the levels of 18S rRNA (P=0.54), were higher in the urinary cells from the 29 patients with a biopsy-confirmed acute rejection than in the 58 recipients without acute rejection. PI-9 levels were significantly higher in patients with type II or higher acute rejection changes compared with those with less than type II changes (P=0.01). Furthermore, PI-9 levels predicted subsequent graft function (r=0.43, P=0.01).

CONCLUSIONS

PI-9 mRNA levels in urinary cells are diagnostic of acute rejection, predict renal allograft histology grade, and predict functional outcome following an acute rejection episode.

CD103 mRNA levels in urinary cells predict acute rejection of renal allografts

BACKGROUND

CD103 is displayed on the cell surface of alloreactive CD8 cytotoxic T lymphocytes (CTLs) and is a critical component for the intraepithelial homing of T cells. Because intratubular localization of mononuclear cells is a feature of acute cellular rejection of renal allografts, we explored the hypothesis that CD103 messenger (m)RNA levels in urinary cells predict acute rejection.

METHODS

We collected 89 urine specimens from 79 recipients of renal allografts. RNA was isolated from the urinary cells, and we measured CD103 mRNA levels and a constitutively expressed 18S ribosomal (r)RNA with the use of real-time quantitative polymerase chain reaction assay.

RESULTS

CD103 mRNA levels, but not 18S rRNA levels, were higher in urinary cells from 30 patients with an episode of acute rejection (32 biopsies and 32 urine samples) compared with the levels in 12 patients with other findings on allograft biopsy (12 biopsies and 12 urine samples), 12 patients with biopsy evidence of chronic allograft nephropathy (12 biopsies and 12 urine samples), and 25 patients with stable graft function after renal transplantation (0 biopsies and 33 urine samples) (P = 0.001; one-way analysis of variance). Acute rejection was predicted with a sensitivity of 59% and a specificity of 75% using natural log-transformed value 8.16 CD103 copies per microgram as the cutoff value (P = 0.001).

CONCLUSION

CD103 mRNA levels in urinary cells are diagnostic of acute rejection of renal allografts. Because CD103 is a cell surface marker of intratubular CD8 CTLs, a noninvasive assessment of cellular traffic into the allograft may be feasible by the measurement of CD103 mRNA levels in urinary cells.

Renin system activation and delayed function of the renal transplant

Delayed graft function (DGF), defined as persistent renal failure that requires dialysis within the first week after kidney transplantation, occurs commonly after cadaveric renal transplantation (CRT). This has important implications for long-term outcome because the 1-year allograft survival rate is significantly reduced when DGF occurs. The mechanisms contributing to the development of DGF are not well established. However, several lines of evidence indicate that excess renin system activity, in both the cadaver kidney donor and recipient, contributes importantly to the pathogenesis of DGF. If this hypothesis can be verified in clinical studies, then pharmacologic agents that interrupt the renin-angiotensin system (eg, type 1 angiotensin II receptor blockade, angiotensin converting enzyme inhibition, and beta-adrenergic blockade) in the donor and recipient might significantly improve the outcome of cadaveric renal transplants.

Noninvasive diagnosis of renal-allograft rejection by measurement of messenger RNA for perforin and granzyme B in urine

BACKGROUND

Acute rejection is a serious and frequent complication of renal transplantation, and its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for rejection could improve the outcome of transplantation.

METHODS

We obtained 24 urine specimens from 22 renal-allograft recipients with a biopsy-confirmed episode of acute rejection and 127 samples from 63 recipients without evidence of acute rejection. RNA was isolated from the urinary cells. Messenger RNA (mRNA) encoding the cytotoxic proteins perforin and granzyme B and a constitutively expressed cyclophilin B gene were measured with the use of a competitive, quantitative polymerase chain reaction, and the level of expression was correlated with allograft status.

RESULTS

The log-transformed mean (+/-SE) levels of perforin mRNA and granzyme B mRNA, which encode cytotoxic proteins, but not the levels of constitutively expressed cyclophiiin B mRNA, were higher in the urinary cells from the 22 patients with a biopsy-confirmed episode of acute rejection than in the 63 recipients without an episode of acute rejection (perforin, 1.4+/-0.3 vs. -0.6+/-0.2 fg per microgram of total RNA; P<0.001; and granzyme B, 1.2+/-0.3 vs. -0.9+/-0.2 fg per microgram of total RNA; P<0.001). Analysis involving the receiver-operating-characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 83 percent and a specificity of 83 percent with the use of a cutoff value of 0.9 fg of perforin mRNA per microgram of total RNA, and with a sensitivity of 79 percent and a specificity of 77 percent with the use of a cutoff value of 0.4 fg of granzyme B mRNA per microgram of total RNA. Sequential urine samples were obtained from 37 patients during the first nine days after transplantation; and measurements of the levels of mRNA that encoded cytotoxic proteins identified those in whom acute rejection developed.

CONCLUSIONS

Measurement of mRNA encoding cytotoxic proteins in urinary cells offers a noninvasive means of diagnosing acute rejection of renal allografts.

The role of air plethysmography in monitoring results of venous surgery

The development of an objective, noninvasive method to assess the hemodynamic effects of venous surgery has long been awaited. Previous methods used to evaluate the results of surgery for varicose veins and venous stasis ulceration have been limited in their quantitative assessment. Now, by use of air plethysmography (APG), we can accurately quantify the effectiveness of corrective venous surgery. Twenty-five extremities that had evidence of venous insufficiency were examined with use of APG before and after venous surgical procedures. Surgery was directed at specific sites of venous incompetence as defined by physical examination and high-resolution duplex imaging. Twenty-one extremities underwent ligation and stripping of the greater saphenous vein. In these patients, APG showed an improvement in venous reflux as demonstrated by a decrease in the venous filling index from 6.6 +/- 0.7 ml/sec to 1.8 +/- 0.3 ml/sec (p = 0.0001) and venous volume from 177.1 +/- 14.5 ml to 139.2 +/- 8.9 ml (p = 0.0008). In addition, these patients showed a mild improvement in calf muscle pump function as noted by an improvement in ejection fraction from 45.8 +/- 2.0% to 50.8% +/- 2.5% (p = 0.07). The residual volume fraction decreased from 45.0% +/- 3.4% to 42.0% +/- 3.7%, a difference that was not statistically significant (p = 0.4). Four extremities with grade III chronic venous insufficiency underwent popliteal vein valve transplantation with use of an autogenous axillary vein valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic similarities between extremities with varicose veins and with chronic venous insufficiency utilizing air plethysmography

Air plethysmography (APG) was used to measure maximal venous outflow rate (MVO), a test for proximal venous obstruction; venous volume; venous filling index, an estimate of valvular incompetence; ejection fraction (EF), a test of calf-muscle pump efficiency; and residual volume fraction (RVF), an estimate of ambulatory venous pressure. MVO was lower in patients with chronic venous insufficiency (CVI) than in those with varicose veins (VV), but the difference was small (p = 0.06). RVF was significantly greater in extremities with CVI when compared with those with VV (p less than 0.01). However, the degree of abnormality in venous volume, venous filling index, and EF was similar in CVI and VV extremities. In summary, although RVF tends to be higher in extremities with CVI when compared with those with VV, there is tremendous overlap between VV and CVI for each of the hemodynamic variables measured by APG. Therefore, the pathophysiology of CVI is likely to involve not only hemodynamic abnormalities but also other factors that have not yet been clearly identified.