Novel transcriptomic signatures associated with premature kidney allograft failure

BACKGROUND

The power to predict kidney allograft outcomes based on non-invasive assays is limited. Assessment of operational tolerance (OT) patients allows us to identify transcriptomic signatures of true non-responders for construction of predictive models.

METHODS

In this observational retrospective study, RNA sequencing of peripheral blood was used in a derivation cohort to identify a protective set of transcripts by comparing 15 OT patients (40% females), from the TOMOGRAM Study (NCT05124444), 14 chronic active antibody-mediated rejection (CABMR) and 23 stable graft function patients ≥15 years (STA). The selected differentially expressed transcripts between OT and CABMR were used in a validation cohort (n = 396) to predict 3-year kidney allograft loss at 3 time-points using RT-qPCR.

FINDINGS

Archetypal analysis and classifier performance of RNA sequencing data showed that OT is clearly distinguishable from CABMR, but similar to STA. Based on significant transcripts from the validation cohort in univariable analysis, 2 multivariable Cox models were created. A 3-transcript (ADGRG3, ATG2A, and GNLY) model from POD 7 predicted graft loss with C-statistics (C) 0.727 (95% CI, 0.638-0.820). Another 3-transcript (IGHM, CD5, GNLY) model from M3 predicted graft loss with C 0.786 (95% CI, 0.785-0.865). Combining 3-transcripts models with eGFR at POD 7 and M3 improved C-statistics to 0.860 (95% CI, 0.778-0.944) and 0.868 (95% CI, 0.790-0.944), respectively.

INTERPRETATION

Identification of transcripts distinguishing OT from CABMR allowed us to construct models predicting premature graft loss. Identified transcripts reflect mechanisms of injury/repair and alloimmune response when assessed at day 7 or with a loss of protective phenotype when assessed at month 3.

FUNDING

Supported by the Ministry of Health of the Czech Republic under grant NV19-06-00031.

Successful Treatment of Anemia With Anaplastic and Microangiopathic Characteristics in a Kidney Transplant Recipient With Parvovirus B19 Infection: A Case Report

BACKGROUND

The prevalence of parvovirus B19 infection in renal transplantation ranges from 2% to 30%. The age and immune status of the patient influence the severity of the clinical picture. A diagnosis is made by taking as evidence the giant proerythroblasts on a bone marrow sample and the parvovirus B19 viral replication with a polymerase chain reaction (PCR) technique at the blood level. Clinically, parvovirus B19 may appear with fever and severe anemia, which can be followed by pancytopenia and thrombotic microangiopathy in some cases. The literature reports a graft dysfunction rate ranging from 10% to 36%. An infection relapse may happen in 30% of cases.

CASE PRESENTATION

We report the case of a 33-year-old patient who underwent a kidney transplant in January of 2018. After transplantation, he reached a creatinine value of 1.1 mg/dL and a hemoglobin (Hb) level of 14 g/dL. In April 2019, he developed mycoplasma pneumonia, with signs of hemolytic anemia on bone marrow aspiration. Eventually, he was admitted because of fever, arthralgia, and anemia, with serologic and bone marrow biopsy evidence of red cell aplasia secondary to parvovirus B19 infection. He was treated with 400 mg/kg intravenous immunoglobulin (IVIg) for 10 days; 18 days after the end of treatment, he reached a creatinine value of 1.15 mg/dL, an Hb of 12.5 g/dL, and a reduction of the viral load from 25,000,000 copies/mL to 1,600,000 copies/mL.

CONCLUSIONS

Anemia with both an aplasic and hemolytic component was successfully treated using immunoglobulin therapy, with a significant fall in the parvovirus B19 viral load.

Hemophagocytic Lymphohistiocytosis in Renal Transplant Recipients: A 2-Case Report

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by an excessive immune activation. HLH can be triggered by a variety of events that disrupt immune homeostasis, such as infections and immunosuppression. HLH presents with heterogeneous clinical symptoms and laboratory findings such as pancytopenia, elevated liver enzymes, impaired renal function, and hyperferritinemia.

CASE PRESENTATIONS

Case 1. A 58-year-old man was admitted because of a high fever and diarrhea. Laboratory findings showed acute renal impairment, pancytopenia, Epstein-Barr virus (EBV) DNA seropositivity with a replication index of 2 million copies/mL, and hyperferritinemia. A diagnosis of HLH was confirmed by bone marrow aspiration. He was treated with etoposide, steroids, and rituximab with initial good response and good kidney function restoration. He was discharged after 31 days but eventually died after 44 days after a disease relapse. Case 2. A 51-year-old kidney transplant recipient was admitted because of a fever of unknown origin. A worsening renal function, pancytopenia, EBV DNA of 4,356,222 copies/mL on blood, D-Dimer 7505 ng/mL, ferritinemia 9180.9 ug/L, and triglycerides 1273 mg/dL were found. Bone marrow aspiration was negative for HLH; a few days later, a diagnosis of HLH was made after a positive bone marrow biopsy. Continuous renal replacement therapy was started in the intensive care unit because of severe lactic acidosis due to sepsis. She died few days later.

CONCLUSION

EBV infection could be a trigger for HLH in a renal transplant patient. Hyperferritinemia is useful for differential diagnosis in a septic patient. The outcome is very poor even with prompt treatment.

Successful Treatment of Focal Segmental Glomerulosclerosis Recurrence in a Second Kidney Transplant Patient: A Case Report

BACKGROUND

Recurrence of focal segmental glomerulosclerosis (FSGS) in renal allograft recipients after first transplant occurs in the second graft in virtually all patients. There is little evidence regarding optimal treatment.

CASE PRESENTATION

A 55-year-old man with primary FSGS and disease recurrence in both the first and the second kidney grafts is presented. In 1999, the patient developed FSGS 3 years after transplant, which was treated with plasmapheresis and cyclophosphamide. Hemodialysis was started at 8 years from the onset of relapse. In February 2014, the patient received a second kidney transplant, and after 2 weeks laboratory analysis showed nephrotic proteinuria (5.9 g/d) with increased serum creatinine. Biopsy results revealed recurrence of FSGS. At that time, he was treated with steroids and plasmapheresis with partial efficacy, achieving a serum creatinine level of 1.1 mg/dL with decreased proteinuria (1 g/d). After 4 months, creatinine worsened (1.6 mg/dL) with new evidence of proteinuria. Second biopsy results showed evidence of FSGS progression. The patient then received plasmapheresis and 2 doses of rituximab. Follow-up was characterized by progressive remission up to complete resolution. The patient is currently free from relapses after 3 years with good renal function and almost no proteinuria.

CONCLUSIONS

More evidence and prospective studies are needed to better understand the role of rituximab in FSGS in order to obtain an optimized therapeutic protocol for recurrence of FSGS in renal transplant recipients.

Acute Kidney Injury Secondary to Hypercalcemia in a Kidney Transplant Patient With Pneumocystis jirovecii Pneumonia: A Case Report

BACKGROUND

Persistent hyperparathyroidism is one of the main causes of hypercalcemia following kidney transplantation; differential diagnosis is required.

CASE PRESENTATION

We report the case of a 61-year-old kidney transplant recipient who underwent transplant in September 2016. She was admitted in March 2017 presenting with a 3-week history of asthenia, hypotension, and cough. Laboratory analysis showed acute kidney injury with hypercalcemia and elevation of inflammatory markers. She was initially treated with hydration therapy. A few days after admission she developed respiratory failure: chest computed tomography showed a ground-glass pattern. A diagnosis of Pneumocystis jirovecii was made on bronchoalveolar lavage. A subsequent graft biopsy was performed that revealed intratubular calcium deposition without signs of rejection. The patient was given trimethoprim/sulfamethoxazole, with improvement in pulmonary and renal function as well as improvement in hypercalcemia.

CONCLUSIONS

P jirovecii infection can trigger activation of intra-alveolar macrophages that leads to extrarenal vitamin D production with subsequent hypercalcemia. This rare event should be considered in renal transplant patients with pulmonary infection accompanied by hypercalcemia. In our case, hypercalcemia also provoked acute kidney injury.

The management of hemodialysis arteriovenous fistulas in well functioning renal transplanted patients: Many doubts, few certainties

Vascular access (VA) for hemodialysis (HD) is one of the most important clinical problems in end-stage renal disease (ESRD) patients because it can limit a life support system and can influence long-term dialysis patient survival. Nevertheless, VA becomes useless after a successful renal transplant. Therefore, we wanted to evaluate the natural history of arteriovenous fistulas (AVF) in renal transplanted patients and the possibility of maintaining the fistula as patent or not.

Methods

A retrospective study was conducted to evaluate kidney transplant patients in our unit from April 1994 to April 2004. We studied 542 patients.

Results

There were 365 patients with a well functioning kidney. Eighty-six patients died. Ninety-one patients were put back on dialysis: 89 patients on HD and two patients on CAPD. Of the 365 patients with functioning kidney transplants, 198 patients demonstrated a patent fistula, while 167 patients had a closed fistula. One hundred and twenty-five patients had a spontaneous closure and 42 patients had a surgical closure. Of the 89 patients put back on dialysis, 49 patients used the previous AVF, while it was necessary to create a new VA in 40 patients.

Conclusions

As demonstrated by the results of our study, after renal transplantation the possibility of spontaneous AVF closure caused by a thrombosis is not a rare event. The dilemma is whether to preserve a fistula that could be useful in case of restarting HD or to perform a systematic fistula closure because of cardiac output and cardiac failure risks. Concerning this question there is no consensus between different authors in the literature. In reviewing the literature and analyzing our data, we conclude that the definite indications for AVF closure in well functioning renal transplanted patients are heart failure, high flow fistula, VA complications and important aesthetic reasons. Routine AVF closure is not indicated until prospective and randomized studies can demonstrate the ability of this procedure to reduce the high incidence of cardiac morbidity and mortality that is present, even after renal transplantation.

Risk of renal cell cancer in people immunodepressed after solid organ transplant: Results from an Italian multicenter cohort study

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Background: The etiology of renal cell cancer (RCC) is poorly understood, and data from immunosuppressed population may help to highlights risk factors unknown in the immune competent population. To assess incidence and risk factors for renal cell cancer (RCC) after kidney and liver transplant (KT and LT, respectively), we carried out a cohort investigation in 24 Italian transplant centers. Methods: This study is part of an ongoing cohort investigation conducted in 24 transplant centers in all of Italy. Two cohorts have been implemented, including 7,217 KT recipients (64.2% men) and 2,770 LT recipients (74.7% men) transplanted between 1997 and 2009—and followed-up until 2010. Person years (PY) at risk of cancer were computed from 30 days after transplant to cancer diagnosis, death, return to dialysis (for KT) or to study closure. The number of observed cancers was compared to that expected in the general population through standardized incidence ratios (SIR) and 95% confidence intervals (CI). To identify risk factors, incidence rate ratios (IRR) were computed through Poisson regression. Results: Overall, 581 cancers were diagnosed during 61,817 PYs of follow-up, with Kaposi’s sarcoma, non-Hodgkin lymphoma, lung, RCC, and prostate as the most common types. Thirty-eight cases of RCC were diagnosed (36 in KT and 2 in LT). As compared to the general population, the risk of RCC was 4.9-fold significantly higher in KT recipients than expected (95% CI: 3.4-6.8). The increased risk was restricted to the native kidney (31 native kidney OR=4.2, 95% CI:2.9-6.0), and no risk elevation was found in LT recipients (SIR=0.5 95% CI: 0.1-1.9). Use of mTOR inhibitors seemed to exert a 40% reduced risk (IRR=0.6, 95% CI: 0.2–1.4) of RCC, but the difference was not statistically significant. Conclusions: Our study findings confirmed, in Italy, the increased risks for RCC following KT, and they also suggested a possible protective effect of mTORi. The magnitude of the excess risk documented in this cohort study was higher than reported for potential risk factors described in immune competent people—or in people under dialysis—thus suggesting a role for the immune system in the etiology of RCC.

Risk of de novo cancers after transplantation: results from a cohort of 7217 kidney transplant recipients, Italy 1997-2009

To assess incidence and risk factors for de novo cancers (DNCs) after kidney transplant (KT), we carried out a cohort investigation in 15 Italian KT centres. Seven thousand two-hundred seventeen KT recipients (64.2% men), transplanted between 1997 and 2007 and followed-up until 2009, represented the study group. Person years (PY) were computed from 30 days after transplant to cancer diagnosis, death, return to dialysis or to study closure. The number of observed DNCs was compared to that expected in the general population of Italy through standardised incidence ratios (SIR) and 95% confidence intervals (CI). To identify risk factors, incidence rate ratios (IRR) were computed. Three-hundred ninety five DNCs were diagnosed during 39.598PYs, with Kaposi's sarcoma (KS), post-transplant lymphoproliferative disorders (PTLD), particularly non-Hodgkin' lymphoma (NHL), lung, kidney and prostate as the most common types. The overall IR was 9.98/1.000PY, with a 1.7-fold augmented SIR (95% CI: 1.6-1.9). SIRs were particularly elevated for KS (135), lip (9.4), kidney carcinoma (4.9), NHL (4.5) and mesothelioma (4.2). KT recipients born in Southern Italy were at reduced risk of kidney cancer and solid tumors, though at a higher KS risk, than those born in Northern Italy. Use of mTOR inhibitors (mTORi) exerted, for all cancers combined, a 46% significantly reduced risk (95% CI: 0.4-0.7). Our study findings confirmed, in Italy, the increased risks for cancer following KT, and they also suggested a possible protective effect of mTORi in reducing the frequency of post transplant cancers.

[Anti-HLA antibodies in nephropathic patients]

BACKGROUND

The presence of anti-human leukocyte antigen (HLA) alloantibodies in nephropathic patients is due to immunogenic stimuli such as transfusions, pregnancies, and transplantations. These stimuli can be highlighted using a classic aspecific serologic technique, such as complement-dependent cytotoxicity (CDC) or using more recent and specific techniques, such as cytofluorimetrics or enzyme linked immunoabsorbant assay (ELISA). Because the presence of anti-HLA preformed antibodies is linked to the largest incidence of both acute and chronic rejection, it seems appropriate to re-evaluate that data obtained using aspecific classic serological analysis techniques by using the more specific cytofluorimetric technique. To aid in the possible prevention of ant-HLA antibody formation, it is also appropriate to analyze the influence of immunogenic stimuli on the development of these antibodies.

METHODS

We studied 116 patients (37 women and 79 men). Anti-HLA antibodies were detected using microlymphotoxic technique after separation of B and T lymphocytes. This separation was obtained using magnetic balls. We used a 30-cell panel. We also used a recent cytofluorimetric test (Flow Pra screening; One Lambda Inc., 21001 Kittridge St., Canoga Park, California, U.S.A.) with a panel of micrograins covered with class I and class II purified antigens. Statistical analysis was performed using chi-square analysis or Fischer s exact test. For each test, sensibility, specificity, and positive and negative value were measured.

RESULTS

Among 33 patients testing positive using the classic CDC-PRA technique (17 positive for B-lymphocytes and 16 positive for both B and T lymphocytes), using cytometry, 25 were positive for anti-HLA-specific antibodies (10 among the B lymphocyte-positive patients and 15 among the B + T lymphocyte-positive patients). Two patients were shown positive only using the cytofluorimetric method. Of the 27 patients positive at cytometry, 18 were positive for class I and class II, 4 for class I, and 5 for class II. FLOW-PRA screening results were less sensitive and more specific. The results obtained by the two methods are comparable(p<0.0001). The immunogenic stimuli found responsible for immunization were: transfusion in 10 of 25 patients, pregnancies in 3/9 patients, transplant in 4/8 patients, and different immunogenic stimuli in 10/12 patients. The results were not statistically significant (p>0.05).

CONCLUSIONS

Data show that positivity for B lymphocytes obtained using CDC-PRA is not always linked to the development of anti-HLA antibodies, whereas positivity for B+T lymphocytes, obtained using CDC -PRA, is often linked to specific antibody development. Immune response is more often directed against class I and II antibodies. The specific detection of HLA antibodies using the cytofluorimetric method allows us to identify patients at risk for rejection, and it suggests that red cells should be filtrated to prevent anti-HLA immunization secondary to transfusion in transplantation candidates.