Banff 07 classification of renal allograft pathology: updates and future directions

An autophagy-associated diagnostic signature based on peripheral blood for antibody-mediated rejection in renal transplantation

BACKGROUND

Antibody-mediated rejection (ABMR) emerged as a major cause of graft loss in renal transplantation. Needle biopsy is the gold standard for diagnosis of ABMR in renal allografts. Thus, noninvasive diagnosis methods of ABMR with high accuracy are urgently needed to prevent unnecessary biopsies.

METHODS

We collected peripheral blood transcriptome data from two independent renal transplantation cohorts with patients with ABMR, stable well-functioning transplants (STA), and T-cell mediated rejection (TCMR). Differentially expressed genes (DEGs) were identified by comparing the ABMR group with the STA group. In addition, functional enrichment analysis and gene set enrichment analysis were performed to seek new key underlying mechanisms in ABMR. Subsequently, we utilized a Boruta algorithm and least absolute shrinkage and selection operator logistic algorithm to establish a diagnostic model which was then evaluated and validated in an independent cohort.

RESULTS

According to functional enrichment analysis, autophagy was found to be the primary upregulated biological process in ABMR. Based on algorithms, three autophagy-associated genes, ubiquitin specific peptidase 33 (USP33), Ras homolog mTORC1 binding (RHEB), and ABL proto-oncogene 2 (ABL2), were selected to establish the diagnostic model in the training cohort. This autophagy-related gene model possessed good diagnostic value in distinguishing ABMR from STA blood samples in the training cohort (AUC = 0.907) and in the validation cohort (AUC = 0.972). In addition, this model also showed good discernibility in distinguishing ABMR from TCMR in the training and validation cohorts (AUCs = 0.908 and 0.833).

CONCLUSION

We identified and validated an autophagy-associated diagnostic model with high accuracy for renal transplant patients with ABMR. Our study provided a new potential test for the non-invasive diagnosis of ABMR in clinical practice and highlighted the importance of autophagy in ABMR.

Surgical Complications Following Renal Transplantation in a Large Institutional Cohort

Background

Successful renal transplantation (RTx) relies on immunosuppression and an optimal surgical course with few surgical complications. Studies reporting the postoperative complications after RTx are heterogeneous and often lack systematic reporting of complications. This study aims to describe and identify postoperative short-term and long-term complications after RTx in a large institutional cohort and identify risk factors for a complicated surgical course.

Methods

The study is a retrospective single-center cohort of 571 recipients who underwent living or deceased donor open RTx between 2014 and 2021. Data were collected on background information and perioperative and postoperative data. Complications were defined as short-term (<30 d) or long-term (>30 d) after transplantation and graded according to the Clavien-Dindo classification. Multivariable logistic regression was performed to evaluate risk factors for serious short-term complications and multivariable time-dependent Cox regression to evaluate risk factors for long-term complications.

Results

A total of 351 patients received a graft from a deceased donor, and 144 of these grafts were on perfusion machine before transplantation. One or more short-term complications occurred in 345 (60%) patients. Previous RTx was associated with short-term Clavien-Dindo >2 complications in recipients (odds ratio = 2.08; 95% confidence interval [CI], 1.18-3.69; P = 0.01). Being underweight (body mass index <18.5) in combination with increasing age increased the odds of short-term Clavien-Dindo >2 and vascular complications. Increasing blood loss per 100 mL was associated with increased odds of short-term Clavien-Dindo >2 (odds ratio = 1.11; 95% CI, 1.01-1.21; P = 0.032). No associations were found for long-term complications after RTx. The 5-y cumulative incidence of graft loss was 12.6% (95% CI, 8.9-16.3).

Conclusions

Short-term complications are common after RTx, and risk factors for severe short-term complications include previous RTx, increasing age, and low body mass index. No risk factors were identified for severe long-term complications. Further studies should explore whether new surgical techniques can reduce surgical complications in RTx.

Kidney Transplantation Outcomes of Patients With Chronic Hypotension in Dialysis

Introduction

Persistent chronic hypotension affects 5-10% of dialysis patients. It seems to be reversible after receiving a functioning graft, but data regarding its influence on transplant outcomes are scarce. We analyze the evolution of patients with chronic hypotension in dialysis who undergo kidney transplantation at our center.

Methods

A retrospective observational study was conducted. Sixty-six patients with chronic hypotension (defined as systolic blood pressure ≤ 100 mm Hg at the time of transplantation) were identified. A control group of 66 non-hypotensive patients was assigned. The evolution of both groups was compared.

Results

Hypotensive patients had higher rates of primary non-function (18.2% vs. 6.1%; P = 0.03) mainly due to venous thrombosis of the allograft, worse renal function at the end of follow-up (eGFR of 35 mL/min/1.73 m2 vs 48 mL/min/1.73 m2, P = 0.001) but there was no statistical difference in graft survival after censoring for primary non-function. After multivariable adjustment, chronic hypotension remained an independent predictor factor for graft failure (adjusted HR of 2.85; 95% CI: 1.24-6.57; P = 0.014). Use of vasoactive drugs and anticoagulation in hypotensive patients was associated with 7.1% of venous graft thrombosis compared to 17.3% in those with no intervention (P = 0.68). Receiving a functioning graft implied blood pressure normalization in patients with chronic hypotension.

Conclusion

Chronic hypotension in dialysis has a negative impact on short-term kidney transplant outcomes but a lower impact on long-term results. It is reversible after receiving a functioning graft. Identifying this subgroup of patients seems crucial to implement measures aimed at improving transplant results.

Renal Disease in Metabolic Syndrome: the Hidden Role of Intrarenal Ischemia

Introduction

The pathogenesis of renal disease in obesity and metabolic syndrome (MS) is mostly unknown. This is in part because of the limited information about renal morphological changes in these conditions. We evaluated renal histology in subjects with MS and those without MS, who are participants in the European Nephrectomy Biobank (ENBiBA) project.

Methods

MS was defined with at least 3 of the following criteria: (i) body mass index (BMI) ≥27 kg/m2; (ii) prediabetes: fasting glucose of 100-125 mg/dl or HbA1c >5.7%; (iii) systolic or diastolic blood pressure >140/90 mm Hg or the use of medications; and (iv) triglycerides >150 mg/dl or high-density lipoprotein cholesterol <40 (in men) or 50 mg/dl (in women). The absence of these criteria defined patients without MS. Exclusion criteria were diabetes or known causes of renal disease.

Results

A total of 157 cases were evaluated: 49 without and 108 with MS. Those with MS were older (54 ± 16 vs. 66 ± 11, P < 0.0001), had more prevalent chronic kidney disease (CKD, estimated glomerular filtration rate [eGFR] <60 ml/min): 24% (23%) versus 4% (8%) (P = 0.02), and had higher albumin-to-creatinine ratio (10 [4-68] vs. 4.45 [0-27], P = 0.05) than those without MS. Global sclerosis (3% [1-7] vs. 7% [3-13], P < 0.0001), nodular sclerosis, mesangial expansion, glomerulomegaly; moderate + severe hyalinosis, and arteriosclerosis were more frequent in those with MS than in those without (88 [82] vs. 29 [59]; 83 [77] vs. 30 [61]; P < 0.05). These vascular changes were independent of differences in age.

Conclusion

In MS, ischemic renal disease may play a role in renal disease. In addition, some patients may develop lesions compatible with diabetic nephropathy such as increased mesangial expansion and nodular sclerosis. Further analyses are needed to study the consequences of the pandemic of obesity on renal health.

Antibody-Suppressor CXCR5+CD8+ T Cells Are More Potent Regulators of Humoral Alloimmunity after Kidney Transplant in Mice Compared to CD4+ Regulatory T Cells

Adoptive cell therapy (ACT), especially with CD4+ regulatory T cells (CD4+ Tregs), is an emerging therapeutic strategy to minimize immunosuppression and promote long-term allograft acceptance, although much research remains to realize its potential. In this study, we investigated the potency of novel Ab-suppressor CXCR5+CD8+ T cells (CD8+ TAb-supp) in comparison with conventional CD25highFoxp3+CD4+ Tregs for suppression of humoral alloimmunity in a murine kidney transplant (KTx) model of Ab-mediated rejection (AMR). We examined quantity of peripheral blood, splenic and graft-infiltrating CD8+ TAb-supp, and CD4+ Tregs in KTx recipients and found that high alloantibody-producing CCR5 knockout KTx recipients have significantly fewer post-transplant peripheral blood and splenic CD8+ TAb-supp, as well as fewer splenic and graft-infiltrating CD4+ Tregs compared with wild-type KTx recipients. ACT with alloprimed CXCR5+CD8+ T cells reduced alloantibody titer, splenic alloprimed germinal center (GC) B cell quantity, and improved AMR histology in CCR5 knockout KTx recipients. ACT with alloprimed CD4+ Treg cells improved AMR histology without significantly inhibiting alloantibody production or the quantity of splenic alloprimed GC B cells. Studies with TCR transgenic mice confirmed Ag specificity of CD8+ TAb-supp-mediated effector function. In wild-type recipients, CD8 depletion significantly increased alloantibody titer, GC B cells, and severity of AMR pathology compared with isotype-treated controls. Anti-CD25 mAb treatment also resulted in increased but less pronounced effect on alloantibody titer, quantity of GC B cells, and AMR pathology than CD8 depletion. To our knowledge, this is the first report that CD8+ TAb-supp cells are more potent regulators of humoral alloimmunity than CD4+ Treg cells.

Transplant nephropathology: Wherefrom, wherein, and whereto

Renal pathology is a relatively recent entry in nephrology. While diseases of the kidney are old, their study began in the 19th century with the report of Richard Bright of the lesions of end-stage kidney disease. Its easy diagnosis from albuminuria soon elevated Bright's nephritis into a leading cause of death. The transformative events in the care of these cases were renal replacement therapy that converted a fatal into a chronic disease, and kidney biopsy that allowed study of the course and pathogenesis of kidney disease. Apart from its fundamental contributions to clinical nephrology, biopsy of renal allografts became an integral component of the evaluation and care of kidney transplant recipients. The Banff transplant pathology conferences launched in 1991 led to developing the classification of allograft pathology into an essential element in the evaluation, treatment, and care of allograft recipients with spirit of discovery. That success came at the cost of increasing complexity leading to the recent realization that it may need the refinement of its consensus-based system into a more evidence-based system with graded statements that are easily accessible to the other disciplines involved in the care of transplanted patients. Collaboration with other medical disciplines, allowing public comment on meeting reports, and incorporation of generative artificial intelligence (AI) are important elements of a successful future. The increased pace of innovation brought about by AI will likely allow us to solve the organ shortage soon and require new classifications for xenotransplantation pathology, tissue engineering pathology, and bioartificial organ pathology.

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.

CXCR5 + CD8 + T Cell-mediated Suppression of Humoral Alloimmunity and AMR in Mice Is Optimized With mTOR and Impaired With Calcineurin Inhibition

BACKGROUND

Adoptive cellular therapy (ACT) with antibody-suppressor CXCR5 + CD8 + T cells (CD8 + T Ab-supp ) inhibits alloantibody production, antibody-mediated rejection (AMR), and prolongs graft survival in multiple transplant mouse models. However, it is not known how conventional immunosuppressive agents impact the efficacy of CD8 + T Ab-supp ACT.

METHODS

We investigated the efficacy of CD8 + T Ab-supp cell ACT when combined with calcineurin inhibitor (CNi) or mammalian target of rapamycin inhibitor (mTORi) in a murine model of kidney transplant.

RESULTS

ACT-mediated decrease in germinal center B cells, posttransplant alloantibody titer, and amelioration of AMR in high alloantibody-producing CCR5 knockout kidney transplant recipients were impaired when ACT was combined with CNi and enhanced when combined with mTORi. CNi (but not mTORi) reduced ACT-mediated in vivo cytotoxicity of IgG + B cells and was associated with increased quantity of germinal center B cells. Neither CNi nor mTORi treatment impacted the expression of cytotoxic effector molecules (FasL, Lamp1, perforin, granzyme B) by CD8 + T Ab-supp after ACT. Concurrent treatment with CNi (but not mTORi) reduced in vivo proliferation of CD8 + T Ab-supp after ACT. The increase in quantity of splenic CD44 + CXCR5 + CD8 + T cells that occurs after ACT was reduced by concurrent treatment with CNi but not by concurrent treatment with mTORi (dose-dependent).

CONCLUSIONS

Impaired efficacy of ACT by CNi is attributed to reduced persistence and/or expansion of CD8 + T Ab-supp cells after ACT. In contrast, concurrent immunosuppression with mTORi preserves CD8 + T Ab-supp cells quantity, in vivo proliferation, and in vivo cytotoxic effector function after ACT and enhances suppression of humoral alloimmunity and AMR.

T follicular helper cells expansion in transplant recipients correlates with graft infiltration and adverse outcomes

Introduction

The process of immunization following vaccination in humans bears similarities to that of immunization with allografts. Whereas vaccination aims to elicit a rapid response, in the transplant recipient, immunosuppressants slow the immunization to alloantigens. The induction of CD4+CXCR5+ T follicular helper (Tfh) cells has been shown to correlate with the success of vaccine immunization.

Method

We studied a cohort of 65 transplant recipients who underwent histological evaluation concurrent with PBMC isolation and follow-up sampling to investigate the phenotypic profiles in the blood and allotissue and analyze their association with clinical events.

Results

The proportion of circulating Tfh cells was heterogeneous over time. Patients in whom this compartment increased had lower CCR7-PD1+CD4+CXCR5+ T cells during follow-up. These patients exhibited more alloreactive CD4+ T cells using HLA-DR-specific tetramers and a greater proportion of detectable circulating plasmablasts than the controls. Examination of baseline biopsies revealed that expansion of the circulating Tfh compartment did not follow prior intragraft leukocyte infiltration. However, multicolor immunofluorescence microscopy of the grafts showed a greater proportion of CXCR5+ T cells than in the controls. CD4+CXCR5+ cells were predominantly PD1+ and were in close contact with B cells in situ. Despite clinical stability at baseline, circulating Tfh expansion was associated with a higher risk of a composite of anti-HLA donor-specific antibodies, rejection, lower graft function, or graft loss.

Conclusion

In otherwise stable patients post-transplant, circulating Tfh expansion can identify ongoing alloreactivity, detectable before allograft injury. Tfh expansion is relevant clinically because it predicts poor graft prognosis. These findings have implications for immune surveillance.

Adult survivors of childhood-onset steroid-dependent and steroid-resistant nephrotic syndrome treated with cyclosporine: a long-term single-center experience

BACKGROUND

Although evidence has confirmed that cyclosporine (CS) is efficacious against childhood-onset steroid-dependent and steroid-resistant nephrotic syndrome (SD/SRNS), some patients may continue to relapse during adulthood. However, predictive factors for adult active disease and kidney complications, such as chronic kidney disease (CKD) and hypertension, in this cohort remain unknown.

METHODS

We conducted a retrospective study on the long-term outcomes of 81 young adults with childhood-onset SD/SRNS treated with CS. The primary endpoint was the probability of active disease into adulthood. The secondary endpoint was the probability of developing kidney complications.

RESULTS

At the last follow-up (median age, 23.2 years; median disease duration, 15.8 years), 44 adult patients (54%) continued to have active disease, whereas 16 patients developed CKD or hypertension, respectively. The proportion of patients developing kidney complications was similar between the active disease and long-term remission groups. Young age at NS onset and history of relapse during the initial CS (median, 31 months) were independent predictive factors for active disease. Acute kidney injury at NS onset, focal segmental glomerulosclerosis, and irreversible CS nephrotoxicity were identified as risk factors for the development of CKD, whereas older age was identified as a risk factor for the development of CKD and hypertension.

CONCLUSIONS

More than 50% of adult survivors treated with CS continued to have active disease, and each 20% developed CKD or hypertension. A long-term follow-up is necessary for patients with SD/SRNS to identify the development of kidney complications later in adulthood that can be attributed to prior disease and CS treatment in childhood, irrespective of disease activity. A higher resolution version of the Graphical abstract is available as Supplementary information.

A Machine Learning-Driven Virtual Biopsy System For Kidney Transplant Patients

In kidney transplantation, day-zero biopsies are used to assess organ quality and discriminate between donor-inherited lesions and those acquired post-transplantation. However, many centers do not perform such biopsies since they are invasive, costly and may delay the transplant procedure. We aim to generate a non-invasive virtual biopsy system using routinely collected donor parameters. Using 14,032 day-zero kidney biopsies from 17 international centers, we develop a virtual biopsy system. 11 basic donor parameters are used to predict four Banff kidney lesions: arteriosclerosis, arteriolar hyalinosis, interstitial fibrosis and tubular atrophy, and the percentage of renal sclerotic glomeruli. Six machine learning models are aggregated into an ensemble model. The virtual biopsy system shows good performance in the internal and external validation sets. We confirm the generalizability of the system in various scenarios. This system could assist physicians in assessing organ quality, optimizing allograft allocation together with discriminating between donor derived and acquired lesions post-transplantation.

Tacrolimus After rATG and Infliximab Induction Immunosuppression-RIMINI Trial

BACKGROUND

Infliximab selectively targets recently activated effector cells and, as an induction agent, might enable the safe elimination of mycophenolate from maintenance immunosuppression in kidney transplantation.

METHODS

This is a phase II international multicenter open-label single-arm confidence interval (CI)-based clinical trial of the BIO-DrIM EU consortium aimed at assessing the efficacy and safety of rabbit antithymocyte globulin and infliximab induction in kidney transplantation. Sixty-seven primary kidney transplant recipients at low risk (panel-reactive antibodies <20%, no donor-specific antibodies [DSA]) received rabbit antithymocyte globulin (2 × 1.5 mg/kg, postoperative days 0 and 1) and infliximab (5 mg/kg, postoperative day 2), followed by mycophenolate-free tacrolimus-based immunosuppression for 12 mo. The primary endpoint was efficacy failure, defined as a composite of acute rejection, graft loss, or poor graft function (estimated glomerular filtration rate <40 mL/min) at 12 mo and was based on the endpoint of the comparator study. Additionally, a historical propensity-matched control cohort was established.

RESULTS

Primary endpoint occurred in 22 of 67 patients (32.84%), with upper bound of an exact 1-sided 95% CI of 43.47%, which met the predefined criteria (efficacy failure of <40% and upper-bound 95% CI of <50%) and was similar in the historical matched cohort. By 12 mo, 79.1% of patients remained on the study protocol. Lower rates of BK replication (6% versus 22.4%; P  = 0.013) but higher rates of de novo DSAs (11.9% versus 1.5%; P  = 0.039) were observed in the study cohort.

CONCLUSIONS

A similar efficacy of the study immunosuppression regimen to the comparator study and the historical matched cohort was found. However, a higher de novo DSA emergence points to an increased risk of antibody-mediated rejection (NCT04114188).

ABO Incompatible Kidney Transplantation Without B-cell Depletion is Associated With Increased Early Acute Rejection: A Single-Center Australian Experience

We performed a single-center retrospective cohort study of 66 consecutive ABO incompatible kidney transplants (ABOiKT) performed without B-cell depleting therapy. Outcomes were compared to an earlier era performed with rituximab (n = 18) and a contemporaneous cohort of ABO compatible live donor transplants (ABOcKT). Acute rejection within 3 months of transplant was significantly more common after rituximab-free ABOiKT compared to ABOiKT with rituximab (OR 8.8, p = 0.04) and ABOcKT (OR 2.9, p = 0.005) in adjusted analyses. Six recipients of rituximab-free ABOiKT experienced refractory antibody mediated rejection requiring splenectomy, and a further two incurred early graft loss with no such episodes amongst ABOiKT with rituximab or ABOcKT cohorts. Patient and graft survival were similar between groups over a median follow-up of 3.1 years. This observational evidence lends strong support to the continued inclusion of rituximab in desensitization protocols for ABOiKT.

A bibliometric and knowledge-map analysis of antibody-mediated rejection in kidney transplantation

OBJECTIVES

Antibody-mediated rejection (AMR) is a large obstacle to the long-term survival of allograft kidneys. It is urgent to find novel strategies for its prevention and treatment. Bibliometric analysis is helpful in understanding the directions of one field. Hence, this study aims to analyze the state and emerging trends of AMR in kidney transplantation.

METHODS

Literature on AMR in kidney transplantation from 1999 to 2022 was collected from the Web of Science Core Collection. HistCite (version 12.03.17), CiteSpace (version 6.2.R2), Bibliometrix 4.1.0 Package from R language, and Gephi (https://gephi.org) were applied to the bibliometric analysis of the annual publications, leading countries/regions, core journals, references, keywords, and trend topics.

RESULTS

A total of 2522 articles related to AMR in kidney transplantation were included in the analysis and the annual publications increased year by year. There were 10874 authors from 118 institutions located in 70 countries/regions contributing to AMR studies, and the United States took the leading position in both articles and citation scores. Halloran PF from Canada made the most contribution to AMR in kidney transplantation. The top 3 productive journals, American Journal of Transplantation, Transplantation, and Transplantation Proceedings, were associated with transplantation. Moreover, the recent trend topics mainly focused on transplant outcomes, survival, and clinical research.

CONCLUSIONS

North American and European countries/regions played central roles in AMR of kidney transplantation. Importantly, the prognosis of AMR is the hotspot in the future. Noninvasive strategies like plasma and urine dd-cfDNA may be the most potential direction in the AMR field.

Evolution of human kidney allograft pathology diagnostics through 30 years of the Banff classification process

The second half of the previous century witnessed a tremendous rise in the number of clinical kidney transplants worldwide. This activity was, however, accompanied by many issues and challenges. An accurate diagnosis and appropriate management of causes of graft dysfunction were and still are, a big challenge. Kidney allograft biopsy played a vital role in addressing the above challenge. However, its interpretation was not standardized for many years until, in 1991, the Banff process was started to fill this void. Thereafter, regular Banff meetings took place every 2 years for the past 30 years. Marked changes have taken place in the interpretation of kidney allograft biopsies, diagnosis, and classification of rejection and other non-rejection pathologies from the original Banff 93 classification. This review attempts to summarize those changes for increasing the awareness and understanding of kidney allograft pathology through the eyes of the Banff process. It will interest the transplant surgeons, physicians, pathologists, and allied professionals associated with the care of kidney transplant patients.

TIMP-2 and IGFBP7 in human kidney biopsies in renal disease

Background

Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) are markers of tubular stress and urinary [TIMP-2]*[IGFBP7] is an established biomarker for risk assessment of acute kidney injury. There are no studies of expression profiles or localization of these markers in human renal tissue with confirmed renal disease.

Methods

We analysed 37 kidney biopsies of patients with renal disease and 10 non-diseased control biopsies for TIMP-2 and IGFBP7 expression using immunohistochemistry. Changes in glomerular morphology were evaluated by a semi-quantitative glomerulosclerosis score (GSI) and tubular interstitial changes were graded by the tubular injury score (TSI) using periodic acid-Schiff-stained paraffin sections. Interstitial fibrosis and tubular atrophy (IF/TA) were graded according to the Banff classification. Urinary [TIMP-2]*[IGFBP7] was collected at the time of biopsy.

Results

TIMP-2 and IGFBP7 had significantly greater expression in kidney biopsies from patients with renal disease compared with control tissue, especially in the tubular compartment. Here, IGFBP7 was detected in proximal and distal tubules while TIMP-2 was predominantly localized in the collecting ducts. Renal injury significantly correlated with staining intensity for TIMP-2 and IGFBP7: GSI weakly correlated with glomerular TIMP-2 (r = 0.36) and IGFBP7 (r = 0.35) and TSI correlated with tubular TIMP-2 (r = 0.41) and IGFBP7 (r = 0.43). Urinary [TIMP-2]*[IGFBP7] correlated weakly with the histopathological damage score but not with glomerular and tubular expression.

Conclusion

Our findings underline the role of TIMP-2/IGFBP7 as an unspecific marker of renal injury that is already in use for early detection of acute kidney injury.

Evaluation of the Modified Oxford Score in Recurrent IgA Nephropathy in North American Kidney Transplant Recipients: The Banff Recurrent Glomerulonephritis Working Group Report

BACKGROUND

The modified Oxford classification mesangial and endocapillary hypercellularity, segmental sclerosis, interstitial fibrosis/tubular atrophy, and the presence of crescents (MEST-C) of immunoglobulin A nephropathy (IgAN) was recently shown to be a predictor of graft failure in Asians with recurrent IgAN. We aimed to validate these findings in a cohort from North American centers participating in the Banff Recurrent Glomerulopathies Working Group.

METHODS

We examined 171 transplant recipients with end-stage kidney disease because of IgAN; 100 of them with biopsy-proven recurrent IgAN (57 of them had complete MEST-C scores) and 71 with no recurrence.

RESULTS

IgAN recurrence, which was associated with younger age at transplantation ( P  = 0.012), strongly increased the risk of death-censored graft failure (adjusted hazard ratio, 5.10 [95% confidence interval (CI), 2.26-11.51]; P  < 0.001). Higher MEST-C score sum was associated with death-censored graft failure (adjusted hazard ratio, 8.57 [95% CI, 1.23-59.85; P  = 0.03] and 61.32 [95% CI, 4.82-779.89; P  = 0.002] for score sums 2-3 and 4-5 versus 0, respectively), and so were the single components endocapillary hypercellularity, interstitial fibrosis/tubular atrophy, and crescents ( P  < 0.05 each). Overall, most of the pooled adjusted hazard ratio estimates associated with each MEST-C component were consistent with those from the Asian cohort (heterogeneity I2 close to 0%, and P  > 0.05).

CONCLUSIONS

Our findings may validate the prognostic usefulness of the Oxford classification for recurrent IgAN and support the inclusion of the MEST-C score in allograft biopsies diagnostic reports.

The Chronology of Renal Allograft Dysfunction: The Pathological Perspectives

BACKGROUND

Antibody-mediated rejection (ABMR), T-cell-mediated rejection (TCMR), BK polyomavirus nephropathy, and calcineurin inhibitor (CNI) toxicity are all common causes of kidney allograft dysfunction that can affect long-term allograft function.

SUMMARY

The prevalence of various pathological diagnoses changes over time for both indication and protocol biopsies. Active ABMR and CNI toxic tubulopathy are the leading causes of kidney allograft dysfunction in the early posttransplant period. Active ABMR can also manifest as thrombotic microangiopathy. Acute TCMR, borderline for acute TCMR, and BK polyomavirus nephropathy will occur, then comes a causal peak of renal allograft dysfunction, followed by chronic active ABMR. Active ABMR in the late posttransplant period would progress to chronic active ABMR, indicating sequential evolution from the incipient to advanced phase of chronic active ABMR. CNI toxicity also manifests as chronic lesions of arteriolar hyalinosis. Interstitial fibrosis and tubular atrophy are the result of multiple insults and are linked to underlying diseases, particularly in the late posttransplant period. Even with established pathological criteria of the Banff scheme, it can be still challenging to clearly delineate the causes of the allograft dysfunction, especially in the complicated cases. Understanding the chronological causes of renal allograft dysfunctions improves comprehension of renal allograft pathology.

KEY MESSAGES

Identifying the time-dependent prevalence of renal allograft dysfunction can be a critical and effective approach to pathological diagnosis.

Investigation of the Association Between ITPA Gene 94C>A Sequence Variant and Kidney Transplant Rejection in Iranian Kidney Transplant Recipients

OBJECTIVES

Thiopurine prodrugs are commonly used in kidney transplant recipients. Inosine triphosphate pyrophosphatase is an enzyme encoded by the ITPA gene. Alteration of ITPA gene is one of the pharmacogenetic sequence variants possibly involved in thiopurine metabolism. The ITPA 94C>A sequence variant (C-to-A substitution at nucleotide 94) is associated with an increased risk of adverse drug reactions in patients treated with the thiopurine drug. The aim of the present study was to investigate the effect of the ITPA 94C>A gene sequence variant in kidney transplant recipients.

MATERIALS AND METHODS

The genotyping of the ITPA rs1127354 variant was performed by the polymerase chain reaction restriction fragment length polymorphism method in 140 kidney transplant recipients and in 100 control participants. Data were analyzed with SPSS statistical software.

RESULTS

The results revealed a significant difference between control and nonrejection groups regarding the rs1127354 genotype and allele frequency. No significant difference was found between the rejection and nonrejection groups regarding the rs1127354 genotype and allele frequency. Also, a significant association was observed between the ageofthe control group and age of the rejection group. No significant differences between sex and underlying disease in patients with or without rejection were observed.

CONCLUSIONS

We observed no significant differences between rejection and nonrejection transplant. Further studies are recommended, in a larger population and with different ethnicities.

Ultrasound elastography in chronic kidney disease: a systematic review and meta-analysis

Ultrasound elastography (USE) is a noninvasive technique for assessing tissue elasticity, and its application in nephrology has aroused growing interest in recent years. The purpose of this article is to systematically review the clinical application of USE in patients with chronic kidney disease (CKD), including native and transplanted kidneys, and quantitatively investigate differences in elasticity values between healthy individuals and CKD patients. Furthermore, we provide a qualitative analysis of the studies included, discussing the potential interplay between renal stiffness, estimated glomerular filtration rate, and fibrosis. In January 2022, a systematic search was carried out on the MEDLINE (PubMed) database, concerning studies on the application of USE in patients with CKD, including patients with transplanted kidneys. The results of the included studies were extracted by two independent researchers and presented mainly through a formal narrative summary. A meta-analysis of nine study parts from six studies was performed. A total of 647 studies were screened for eligibility and, after applying the exclusion and inclusion criteria, 69 studies were included, for a total of 6728 patients. The studies proved very heterogeneous in terms of design and results. The shear wave velocity difference of - 0.82 m/s (95% CI: - 1.72-0.07) between CKD patients and controls was not significant. This result agrees with the qualitative evaluation of included studies that found controversial results for the relationship between renal stiffness and glomerular filtration rate. On the contrary, a clear relationship seems to emerge between USE values and the degree of fibrosis. At present, due to the heterogeneity of results and technical challenges, large-scale application in the monitoring of CKD patients remains controversial.

Mesangiolysis in Pathological Chronic Active Antibody-Mediated Rejection in Kidney Transplant Biopsies

INTRODUCTION

This study aimed to determine if immune or nonimmune and acute or chronic lesions associated with mesangiolysis (MGLS) occurred in biopsy-proven pathological chronic active antibody-mediated rejection (P-CAABMR) in kidney transplant biopsies.

METHODS

We evaluated MGLS in 41 patients with biopsy findings of P-CAABMR from January 2016 to December 2019. Histological scoring was evaluated by Banff classification. Multivariate logistic regression analysis was performed using a forward selection method.

RESULTS

Fifteen of the 41 P-CAABMR biopsies (36.6%) cases showed MGLS. The estimated glomerular filtration rate (eGFR) was significantly lower in the MGLS-positive compared with the MGLS-negative group, and proteinuria was significantly higher in the MGLS-positive compared with the MGLS-negative group. In the clinical model, multivariate analysis was performed using covariates of eGFR and duration after transplantation significantly correlated with MGLS by simple analysis, in addition to type of calcineurin inhibitor use (tacrolimus or cyclosporine), donor-specific antibodies, diabetes, and hypertension grade defined by use of antihypertensive therapy or/and blood pressure level. Only hypertension grade was significantly correlated with MGLS. In the pathological model, multivariate analysis was performed using the presence of FSGS and the aah and cg scores significantly correlated with MGLS by simple analysis, in addition to g and ptc scores. The cg score was significantly correlated with hypertension grade, duration after transplantation, g, ah, and aah.

CONCLUSION

Lower graft function and higher proteinuria was observed in MGLS of P-CAABMR. The Banff cg score was independently related to MGLS in multivariate analysis. Sustained glomerulitis, calcineurin inhibitor nephrotoxicity, and hypertension may cause Banff cg lesions, leading to MGLS in P-CAABMR.

Vesicoureteral Reflux Causes Interstitial Inflammation in Pediatric Kidney Allograft: A Clinicopathological Analysis of 1-Year Protocol Biopsies

INTRODUCTION

At present, there is limited evidence of the histological impact of vesicoureteral reflux (VUR) on pediatric kidney allografts. In this study, we aimed to investigate the relationship between VUR diagnosed by voiding cystourethrography (VCUG) and 1-year protocol biopsy results.

METHODS

One hundred thirty-eight pediatric kidney transplantations were performed in Toho University Omori Medical Center between 2009 and 2019. We included 87 pediatric transplant recipients who were evaluated for VUR by VCUG prior to or at the time of the 1-year protocol biopsy and underwent a 1-year protocol biopsy after transplantation. We evaluated the clinicopathological findings of the VUR and non-VUR groups, and histological scores were evaluated using the Banff score. Tamm-Horsfall protein (THP) within the interstitium was identified by light microscopy.

RESULTS

Of the 87 transplant recipients, 18 cases (20.7%) were diagnosed with VUR by VCUG. The clinical background and findings were not significantly different between the VUR and non-VUR groups. The pathological findings revealed a significantly higher Banff total interstitial inflammation (ti) score in the VUR group than in the non-VUR group. Multivariate analysis indicated a significant relationship between the Banff ti score and THP within the interstitium, and VUR. The 3-year protocol biopsy results (n = 68) revealed a significantly higher Banff interstitial fibrosis (ci) score in the VUR group than in the non-VUR group.

CONCLUSION

VUR caused interstitial fibrosis in the 1-year pediatric protocol biopsies, and interstitial inflammation at the 1-year protocol biopsy may affect interstitial fibrosis at the 3-year protocol biopsy.

Unsatisfactory reproducibility of interstitial inflammation scoring in allograft kidney biopsy

Interstitial inflammation scoring is incorporated into the Banff Classification of Renal Allograft Pathology and is essential for the diagnosis of T-cell mediated rejection. However, its reproducibility, including inter-rater and intra-rater reliabilities, has not been carefully investigated. In this study, eight renal pathologists from different hospitals independently scored 45 kidney allograft biopsies with varying extents of interstitial inflammation. Inter-rater reliabilities and intra-rater reliabilities were investigated by kappa statistics and conditional agreement probabilities. Individual pathologists' scoring patterns were examined by chi-squared tests and proportions tests. The mean pairwise kappa values for inter-rater reliability were 0.27, 0.30, and 0.26 for the Banff i score, ti score, and i-IFTA, respectively. No rater pair performed consistently better or worse than others on all three scorings. After dichotomizing the scores into two groups (none/mild and moderate/severe inflammation), the averaged conditional agreements ranged from 47.1% to 50.0%. The distributions of the scores differed, but some pathologists persistently scored higher or lower than others. Given the important role of interstitial inflammation scoring in the diagnosis of T-cell mediated rejection, transplant practitioners should be aware of the possible clinical implications of the far-from-optimal reproducibility.

An automated histological classification system for precision diagnostics of kidney allografts

For three decades, the international Banff classification has been the gold standard for kidney allograft rejection diagnosis, but this system has become complex over time with the integration of multimodal data and rules, leading to misclassifications that can have deleterious therapeutic consequences for patients. To improve diagnosis, we developed a decision-support system, based on an algorithm covering all classification rules and diagnostic scenarios, that automatically assigns kidney allograft diagnoses. We then tested its ability to reclassify rejection diagnoses for adult and pediatric kidney transplant recipients in three international multicentric cohorts and two large prospective clinical trials, including 4,409 biopsies from 3,054 patients (62.05% male and 37.95% female) followed in 20 transplant referral centers in Europe and North America. In the adult kidney transplant population, the Banff Automation System reclassified 83 out of 279 (29.75%) antibody-mediated rejection cases and 57 out of 105 (54.29%) T cell-mediated rejection cases, whereas 237 out of 3,239 (7.32%) biopsies diagnosed as non-rejection by pathologists were reclassified as rejection. In the pediatric population, the reclassification rates were 8 out of 26 (30.77%) for antibody-mediated rejection and 12 out of 39 (30.77%) for T cell-mediated rejection. Finally, we found that reclassification of the initial diagnoses by the Banff Automation System was associated with an improved risk stratification of long-term allograft outcomes. This study demonstrates the potential of an automated histological classification to improve transplant patient care by correcting diagnostic errors and standardizing allograft rejection diagnoses.ClinicalTrials.gov registration: NCT05306795 .

Evaluation of the efficacy of HEMO2life®, a marine OXYgen carrier for Organ Preservation (OxyOp2) in renal transplantation: study protocol for a multicenter randomized trial

BACKGROUND

Preventing ischemia‒reperfusion injury (IRI) is a major issue in kidney transplantation, particularly for transplant recipients receiving a kidney from extended criteria donors (ECD). The main consequence of IRI is delayed graft function (DGF). Hypoxia is one of the key factors in IRI, suggesting that the use of an oxygen carrier as an additive to preservation solution may be useful. In the OxyOp trial, we showed that the organs preserved using the oxygen carrier HEMO2life® displayed significantly less DGF. In the OxyOp2 trial, we aim to definitively test and quantify the efficacy of HEMO2life® for organ preservation in a large population of kidney grafts.

METHODS

OxyOp2 is a prospective, multicenter, randomized, comparative, single-blinded, parallel-group study versus standard of care in renal transplantation. After the selection of a suitable donor according to the inclusion/exclusion criteria, both kidneys will be used in the study. Depending on the characteristics of the donor, both kidneys will be preserved either in static cold storage (standard donors) or on machine perfusion (for ECD and deceased-after-cardiac-death donors (DCD)). The kidneys resulting from one donor will be randomized: one to the standard-of-care arm (organ preserved in preservation solution routinely used according to the local practice) and the other to the active treatment arm (HEMO2life® on top of routinely used preservation solution). HEMO2life® will be used for ex vivo graft preservation at a dose of 1 g/l preservation solution. The primary outcome is the occurrence of DGF, defined as the need for renal replacement therapy during the first week after transplantation.

DISCUSSION

The use of HEMO2life® in preservation solutions is a novel approach allowing, for the first time, the delivery of oxygen to organs. Improving graft survival by limiting ischemic lesions is a major public-health goal in the field of organ transplantation.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT04181710 . registered on November 29, 2019.

Utility of Banff Human Organ Transplant Gene Panel in Human Kidney Transplant Biopsies

BACKGROUND

Microarray transcript analysis of human renal transplantation biopsies has successfully identified the many patterns of graft rejection. To evaluate an alternative, this report tests whether gene expression from the Banff Human Organ Transplant (B-HOT) probe set panel, derived from validated microarrays, can identify the relevant allograft diagnoses directly from archival human renal transplant formalin-fixed paraffin-embedded biopsies. To test this hypothesis, principal components (PCs) of gene expressions were used to identify allograft diagnoses, to classify diagnoses, and to determine whether the PC data were rich enough to identify diagnostic subtypes by clustering, which are all needed if the B-HOT panel can substitute for microarrays.

METHODS

RNA was isolated from routine, archival formalin-fixed paraffin-embedded tissue renal biopsy cores with both rejection and nonrejection diagnoses. The B-HOT panel expression of 770 genes was analyzed by PCs, which were then tested to determine their ability to identify diagnoses.

RESULTS

PCs of microarray gene sets identified the Banff categories of renal allograft diagnoses, modeled well the aggregate diagnoses, showing a similar correspondence with the pathologic diagnoses as microarrays. Clustering of the PCs identified diagnostic subtypes including non-chronic antibody-mediated rejection with high endothelial expression. PCs of cell types and pathways identified new mechanistic patterns including differential expression of B and plasma cells.

CONCLUSIONS

Using PCs of gene expression from the B-Hot panel confirms the utility of the B-HOT panel to identify allograft diagnoses and is similar to microarrays. The B-HOT panel will accelerate and expand transcript analysis and will be useful for longitudinal and outcome studies.

Effects of Treating Subclinical Rejection 2 Weeks After Kidney Transplantation, as Determined by Analyzing 1-Year Histologic Outcomes

Subclinical rejection (SCR) is associated with chronic allograft nephropathy. Therefore, early detection and treatment of SCR through a protocol biopsy (PB) can reduce the incidence of pathologic changes. This study evaluates the impact of early detection and treatment of SCR using a routine PB 2 weeks after kidney transplantation (KT) by examining histologic outcomes 1 year later. We reviewed 624 KT recipients at the Samsung Medical Center between August 2012 and December 2018. Protocol biopsy was planned 2 weeks and 1 year after transplantation. We compared the histologic changes between the 2 biopsies. After a propensity score matching analysis, we divided the patients into 2 groups: the proven normal group (n = 256) and the rejection group (n = 96) at the PB taken 2 weeks post-transplant. The rejection group showed no significant difference from the normal group in the flow of graft function or the Kaplan-Meier curve for graft survival. In the histologic outcomes, the pathologic differences between the groups significantly improved between the 2 time points. Treating SCR through a PB 2 weeks after KT can contribute to the maintenance of graft function and improve histologic changes 1 year after KT.

Discovery of cellular and genetic signatures of immune tolerance in kidney transplant recipients through single cell RNA sequencing analysis

The objective of this study was to uncover distinct cellular and genetic signatures of transplant operational tolerance (TOT) in kidney transplant recipients (KTRs) through single cell RNA sequencing (scRNA-seq) using peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from 12 KTRs, including those with TOT (TOT, n = 4), stable allograft function on maintenance immunosuppression (STA, n = 4) and biopsy-proven allograft rejection (BPAR, n = 4). ScRNA-seq of PBMCs was analyzed using 20 cell surface marker antibody sequencing to annotate clusters and 399 immune response panel to identify gene expression. Differences in cellular distribution and gene expression were compared among the three groups. Heatmap hierarchical clustering showed that overall cellular distribution pattern was distinct in TOT in comparison with those in the other two groups, with the proportion of B cells being higher in TOT, attributed to immature B cell fraction (TOT vs. STA vs. BPAR: 4.61% vs. 1.27% vs. 2.53%, p = 0.01). Transcript analysis of B cells revealed that genes involved in allo-immune pathway were downregulated in TOT. In T cell subset analysis, the proportion of naïve T cells and regulatory T cells (Tregs) was increased. In transcript analysis, genes associated with inflammation were decreased, while expression levels of CCR6 in Tregs were increased in TOT. Proportions of NKT and NK cells were increased in TOT than in the other two groups. This study showed that TOT has distinct cellular and genetic signatures such as increases of immature B cells, naïve T cells and Tregs and high expression levels of CCR6 in Tregs.

Diagnostic accuracy of ultrasound-based multimodal radiomics modeling for fibrosis detection in chronic kidney disease

OBJECTIVES

To predict kidney fibrosis in patients with chronic kidney disease using radiomics of two-dimensional ultrasound (B-mode) and Sound Touch Elastography (STE) images in combination with clinical features.

METHODS

The Mindray Resona 7 ultrasonic diagnostic apparatus with SC5-1U convex array probe (bandwidth frequency of 1-5 MHz) was used to perform two-dimensional ultrasound and STE software. The severity of cortical tubulointerstitial fibrosis was divided into three grades: mild interstitial fibrosis and tubular atrophy (IFTA), fibrotic area < 25%; moderate IFTA, fibrotic area 26-50%; and severe IFTA, fibrotic area > 50%. After extracting radiomics from B-mode and STE images in these patients, we analyzed two classification schemes: mild versus moderate-to-severe IFTA, and mild-to-moderate versus severe IFTA. A nomogram was constructed based on multiple logistic regression analyses, combining clinical and radiomics. The performance of the nomogram for differentiation was evaluated using receiver operating characteristic (ROC), calibration, and decision curves.

RESULTS

A total of 150 patients undergoing kidney biopsy were enrolled (mild IFTA: n = 74; moderate IFTA: n = 33; severe IFTA: n = 43) and randomized into training (n = 105) and validation cohorts (n = 45). To differentiate between mild and moderate-to-severe IFTA, a nomogram incorporating STE radiomics, albumin, and estimated glomerular filtration (eGFR) rate achieved an area under the ROC curve (AUC) of 0.91 (95% confidence interval [CI]: 0.85-0.97) and 0.85 (95% CI: 0.77-0.98) in the training and validation cohorts, respectively. Between mild-to-moderate and severe IFTA, the nomogram incorporating B-mode and STE radiomics features, age, and eGFR achieved an AUC of 0.93 (95% CI: 0.89-0.98) and 0.83 (95% CI: 0.70-0.95) in the training and validation cohorts, respectively. Finally, we performed a decision curve analysis and found that the nomogram using both radiomics and clinical features exhibited better predictability than any other model (DeLong test, p < 0.05 for the training and validation cohorts).

CONCLUSION

A nomogram based on two-dimensional ultrasound and STE radiomics and clinical features served as a non-invasive tool capable of differentiating kidney fibrosis of different severities.

KEY POINTS

• Radiomics calculated based on the ultrasound imaging may be used to predict the severities of kidney fibrosis. • Radiomics may be used to identify clinical features associated with the progression of tubulointerstitial fibrosis in patients with CKD. • Non-invasive ultrasound imaging-based radiomics method with accuracy aids in detecting renal fibrosis with different IFTA severities.

Uncovering a novel role of focal adhesion and interferon-gamma in cellular rejection of kidney allografts at single cell resolution

Background

Kidney transplant recipients are currently treated with nonspecific immunosuppressants that cause severe systemic side effects. Current immunosuppressants were developed based on their effect on T-cell activation rather than the underlying mechanisms driving alloimmune responses. Thus, understanding the role of the intragraft microenvironment will help us identify more directed therapies with lower side effects.

Methods

To understand the role of the alloimmune response and the intragraft microenvironment in cellular rejection progression, we conducted a Single nucleus RNA sequencing (snRNA-seq) on one human non-rejecting kidney allograft sample, one borderline sample, and T-cell mediated rejection (TCMR) sample (Banff IIa). We studied the differential gene expression and enriched pathways in different conditions, in addition to ligand-receptor (L-R) interactions.

Results

Pathway analysis of T-cells in borderline sample showed enrichment for allograft rejection pathway, suggesting that the borderline sample reflects an early rejection. Hence, this allows for studying the early stages of cellular rejection. Moreover, we showed that focal adhesion (FA), IFNg pathways, and endomucin (EMCN) were significantly upregulated in endothelial cell clusters (ECs) of borderline compared to ECs TCMR. Furthermore, we found that pericytes in TCMR seem to favor endothelial permeability compared to borderline. Similarly, T-cells interaction with ECs in borderline differs from TCMR by involving DAMPS-TLRs interactions.

Conclusion

Our data revealed novel roles of T-cells, ECs, and pericytes in cellular rejection progression, providing new clues on the pathophysiology of allograft rejection.

Significance of Multinucleated Polyploidization of Tubular Epithelial Cells in Kidney Allografts

INTRODUCTION

Multinucleated polyploidization (MNP) of tubular epithelial cells is occasionally observed in kidney allografts. The present study aimed to clarify the clinical and pathological significance of MNP of tubular epithelial cells in kidney allografts.

METHODS

Fifty-eight 1-year biopsies from 58 patients who underwent kidney transplantation at our hospital from January 2016 to December 2017 were included. MNP was counted in each specimen, and the specimens were divided into two groups by the median value. The differences in clinical and pathological characteristics were compared. Ki67-positive cells were counted among tubular epithelial cells to explore the association between cell cycle and MNP. In an additional cohort, MNP was compared between biopsies after precedent T-cell-mediated rejection and precedent medullary ray injury.

RESULTS

The 58 cases were divided into two groups by the median total amount of MNP: group A (MNP > 3) and group B (MNP ≤ 3). Maximum t-score before the 1-year biopsy was significantly higher in group A compared with group B. Other clinical or histological characteristics did not differ significantly. Total amount of Ki67-positive tubular epithelial cells was significantly correlated with total amount of MNP. Significantly higher amount of MNP was observed in cases with precedent T-cell-mediated rejection compared with precedent medullary ray injury. On receiver operating characteristic curve analysis, the cut-off value of MNP to predict precedent T-cell-mediated rejection was 8.5.

CONCLUSIONS

MNP in tubular epithelial cells reflects prior tubular inflammation in kidney allografts. High amount of MNP indicates precedent T-cell-mediated rejection rather than precedent medullary ray injury caused by nonimmune etiologies.

On a Long and Winding Road: Alloantibodies in Organ Transplantation

Today we know that both the humoral and the cellular arm of the immune system are engaged in severe immunological challenges. A close interaction between B and T cells can be observed in most "natural" challenges, including infections, malignancies, and autoimmune diseases. The importance and power of humoral immunity are impressively demonstrated by the current coronavirus disease 2019 pandemic. Organ transplant rejection is a normal immune response to a completely "artificial" challenge. It took a long time before the multifaceted action of different immunological forces was recognized and a unified, generally accepted opinion could be formed. Here, we address prominent paradigms and paradigm shifts in the field of transplantation immunology. We identify several instances in which the transplant community missed a timely paradigm shift because essential, available knowledge was ignored. Moreover, we discuss key findings that critically contributed to our understanding of transplant immunology but sometimes developed with delay and in a roundabout way, as was the case with antibody-mediated rejection-a main focus of this article. These include the discovery of the molecular principles of histocompatibility, the recognition of the microcirculation as a key interface of immune damage, the refinement of alloantibody detection, the description of C4d as a footmark of endothelium-bound antibody, and last but not least, the developments in biopsy-based diagnostics beyond conventional morphology, which only now give us a glimpse of the enormous complexity and pathogenetic diversity of rejection.

HLA-DPB1 molecular mismatches are risk factors for acute rejection and low 5-year graft function in first kidney transplants

The study aimed to investigate the impact of HLA-DPB1 allelic and molecular mismatches on the occurrence of acute rejection (AR) and low 5-year graft function (5Y-GF) in first kidney transplant (KT) recipients. This is a single center retrospective study of 130 deceased donor KT recipients transplanted between 2014 and 2016. HLA-DPB1 allelic MM and the following molecular MM (mMM) were analyzed: expression MM with the high expression G allele in the donor; T cell epitope MM (TCE MM); epitope MM (EMM), considering all six hypervariable regions (EMM-ABCDEF HVR), or only ABEF regions (EMM-ABEF HVR); eplet MM (EpMM); antibody-verified eplet MM (AbVer EpMM); and solvent accessible amino acid MM (SAMM). There was no association of allelic MM with AR or 5Y-GF. The variables independently associated (Cox regression analyses) with AR were high donor final creatinine, nonpermissive TCE MM, ABCDEF EMM load ≥6, EpMM load ≥6; SAMM load ≥5, and AbVer EpMM load ≥3. No association between any HLA-DPB1 mMM and 5Y-GF was observed when all 130 transplant recipients were considered. However, when transplants from expanded criteria donors were excluded, independent associations were detected (logistic regression analyses) with AbVerEpMM load ≥2, SAMM load ≥7, cerebro-vascular death, donor age, and AR. To our knowledge, this is the first study that shows that some HLA-DPB1 mMM are associated with AR and low 5Y-GF in a population of exclusively first kidney transplant recipients.

A prospective, randomized, non-blinded, non-inferiority pilot study to assess the effect of low-dose anti-thymocyte globulin with low-dose tacrolimus and early steroid withdrawal on clinical outcomes in non-sensitized living-donor kidney recipients

BACKGROUND

The optimal dose of anti-thymocyte globulin (ATG) as an induction regimen in Asian living-donor kidney recipients is unclear.

METHODS

This is a pilot study in which 36 consecutive patients undergoing living-donor kidney transplantation were randomly assigned to receive either 4.5 mg/kg (n = 19) or 6.0 mg/kg (n = 17) of ATG; all patients had corticosteroid withdrawal within 7 days. The primary end point was a composite of biopsy-proven acute rejection, de novo donor-specific antibody formation, and graft failure.

RESULTS

At 12 months post-transplant, biopsy-proven acute rejection was more common in the ATG4.5 group (21.1%) than in the ATG6.0 group (0%)(P = .048). Importantly, the rate of the composite end point was significantly higher in the ATG4.5 group (36.8% vs 0%)(P = .006). There were significant differences in neither the renal function nor adverse events between the two groups. One case of death-censored graft failure occurred in the ATG4.5 group and no mortality was observed overall. Compared with pre-transplantation, T cells, natural killer (NK) cells, and natural killer T (NKT) cells were significantly decreased in the first week post-transplantation except for B cells. Although T and NKT cells in both groups and NK cells in the ATG4.5 group had recovered to the pre-transplant levels, NK cells in the ATG6.0 group remained suppressed until six months post-transplant.

CONCLUSIONS

Compared with ATG 6.0 mg/kg, ATG 4.5 mg/kg with early corticosteroid withdrawal and low dose maintenance regimen was associated with higher rates of acute rejection in non-sensitized Asian living-donor kidney recipients.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02447822.

The Protective Role of Protocol Biopsy for Allograft Kidney Maintenance in Kidney Transplantation

Many studies have reported that protocol biopsy (PB) may help preserve kidney function in kidney transplant recipients. Early detection and treatment of subclinical rejection may reduce the incidence of chronic antibody-mediated rejection and graft failure. However, no consensus has been reached regarding PB effectiveness, timing, and policy. This study aimed to evaluate the protective role of routine PB performed 2 weeks and 1 year after kidney transplantation. We reviewed 854 kidney transplant recipients at the Samsung Medical Center between July 2007 and August 2017, with PBs planned at 2 weeks and 1 year after transplantation. We compared the trends in graft function, chronic kidney disease (CKD) progression, new-onset CKD, infection, and patient and graft survival between the 504 patients who underwent PB and 350 who did not undergo PB. The PB group was again divided into 2 groups: the single PB group (n = 207) and the double PB group (n = 297). The PB group was significantly different from the no-PB group in terms of the trends in graft function (estimated glomerular filtration rate). The Kaplan-Meier curve showed that PB did not significantly improve graft or overall patient survival. However, in the multivariate Cox analysis, the double PB group had advantages in graft survival, CKD progression, and new-onset CKD. PB can play a protective role in the maintenance of kidney grafts in kidney transplant recipients.

Long-term Prolonged-release Tacrolimus-based Immunosuppression in De Novo Kidney Transplant Recipients: 5-Y Prospective Follow-up of Patients in the ADVANCE Study

Although prolonged-release tacrolimus (PR-T) is widely approved for posttransplantation immunosuppression in kidney recipients, large-scale studies are required to assess long-term outcomes. We present follow-up data from the Advagraf-based Immunosuppression Regimen Examining New Onset Diabetes Mellitus in Kidney Transplant Recipients (ADVANCE) trial, in which kidney transplant patients (KTPs) received corticosteroid minimization with PR-T.

Methods

ADVANCE was a 24-wk, randomized, open-label, phase-4 study. De novo KTPs received PR-T with basiliximab and mycophenolate mofetil and were randomized to receive an intraoperative corticosteroid bolus plus tapered corticosteroids until day 10 (arm 1) or an intraoperative corticosteroid bolus (arm 2). In this 5-y, noninterventional follow-up, patients received maintenance immunosuppression according to standard practice. The primary endpoint was graft survival (Kaplan-Meier). Secondary endpoints included patient survival, biopsy-confirmed acute rejection-free survival, and estimated glomerular filtration rate (4-variable modification of diet in renal disease).

Results

Follow-up study included 1125 patients. Overall graft survival at 1 and 5 y posttransplantation was 93.8% and 88.1%, respectively, and was similar between treatment arms. At 1 and 5 y, patient survival was 97.8% and 94.4%, respectively. Five-year graft and patient survival rates in KTPs who remained on PR-T were 91.5% and 98.2%, respectively. Cox proportional hazards analysis demonstrated similar risk of graft loss and death between treatment arms. Five-year biopsy-confirmed acute rejection-free survival was 84.1%. Mean ± standard deviation values of estimated glomerular filtration rate were 52.7 ± 19.5 and 51.1 ± 22.4 mL/min/1.73 m² at 1 and 5 y, respectively. Fifty adverse drug reactions were recorded, probably tacrolimus-related in 12 patients (1.5%).

Conclusions

Graft survival and patient survival (overall and for KTPs who remained on PR-T) were numerically high and similar between treatment arms at 5 y posttransplantation.

The impact of induction therapy in low-immunological risk kidney transplant recipients regardless of HLA matching

BACKGROUND

Induction agents have proved to reduce the rate of acute rejection (AR) in kidney transplant recipients (KTRs) without improving long-term graft and patient survival (PS).

OBJECTIVE

This study evaluates the utility of induction therapy in low immunological risk KTRs regardless of donor-to-recipient HLA matching.

METHODS

We retrospectively reviewed the records of 218 patients undergoing kidney transplantation (KT). These patients were divided into two groups according to the usage of induction therapy: 82 did not receive any induction therapy (Group I), and 136 patients received either Anti-IL2 receptor antibodies or anti-thymocyte globulin (Group II). All patients had panel reactive antibody (PRA) < 20% and absence of donor-specific antibodies (DSA). The difference in outcomes were assessed at different intervals following KT.

RESULTS

The rate of bacterial infections at one year (p-value = 0.032) and the frequency of CMV disease (p-value = 0.044) were significantly higher in Group II (with induction therapy). The duration of hospital stay, the rate and severity of acute rejection, the occurrence of delayed graft function, the rate and type of surgical complications at one year, and the graft function and survival at one and three years were similar between the two groups (p-value = NS). In addition, the financial burden is much less in Group I (without induction therapy), reducing the total cost of the transplant procedure.

CONCLUSION

We conclude that induction therapy in low-immunological risk kidney transplant patients is not a must regardless of donor-to-recipient HLA matching. Therefore, induction therapy did not yield significant health results, but had negative financial consequences.

Acute and Chronic Systemic Inflammation: Features and Differences in the Pathogenesis, and Integral Criteria for Verification and Differentiation

Currently, there is rationale for separating the systemic manifestations of classical inflammation from systemic inflammation (SI) itself as an independent form of the general pathological process underlying the pathogenesis of the most severe acute and chronic diseases. With this aim in view, we used integral scales of acute and chronic SI (ChSI), including the following blood plasma parameters: interleukins 6, 8, 10; tumor necrosis factor alpha; C-reactive protein; D-dimer; cortisol; troponin I; myoglobin. The presence of multiple organ dysfunction according to the SOFA score was also taken into account. The effectiveness of the scales was tested in groups of intensive care patients during different periods of acute trauma, sepsis, and septic shock. The ChSI scale was applicable under systemic autoimmune diseases, chronic purulent infections, chronic limb threatening ischemia, and end-stage renal disease of various genesis. The number of examined patients was 764 in total. The scales allowed us to verify specific phases of acute SI and identify pathogenetic risk factors of lethal outcomes, as well as the most severe variants of the chronic pathologies course. These scales are open adaptable systems (in terms of the nomenclature and choice of indicators). They are primarily intended for scientific research. However, the SI verification methodology presented in this paper may be useful for developing advanced criteria for assessing both the typical links in the pathogenesis of many diseases and the severity of the overall condition of patients for clinical practice.

Automated scoring of total inflammation in renal allograft biopsies

BACKGROUND

Computer-assisted scoring is gaining prominence in the evaluation of renal histology; however, much of the focus has been on identifying larger objects such as glomeruli. Total inflammation impacts graft outcome, and its quantification requires tools to identify objects at the cellular level or smaller. The goal of the current study was to use CD45 stained slides coupled with image analysis tools to quantify the amount of non-glomerular inflammation within the cortex.

METHODS

Sixty renal transplant whole slide images were used for digital image analysis. Multiple thresholding methods using pixel intensity and object size were used to identify inflammation in the cortex. Additionally, convolutional neural networks were used to separate glomeruli from other objects in the cortex. This combined measure of inflammation was then correlated with rescored Banff total inflammation classification and outcomes.

RESULTS

Identification of glomeruli on biopsies had high fidelity (mean pixelwise dice coefficient of .858). Continuous total inflammation scores correlated well with Banff rescoring (maximum Pearson correlation .824). A separate set of thresholds resulted in a significant correlation with alloimmune graft loss.

CONCLUSIONS

Automated scoring of inflammation showed a high correlation with Banff scoring. Digital image analysis provides a powerful tool for analysis of renal pathology, not only because it is reproducible and can be automated, but also because it provides much more granular data for studies.

Short-term outcomes after transplantation of deceased donor kidneys with acute kidney injury: a retrospective analysis of a multicenter cohort of marginal donor kidneys with post-explantation biopsies

BACKGROUND

Deceased donor kidneys with acute kidney injury (AKI) are often discarded because of concerns about inferior transplant outcomes. A means of grading the quality of such kidneys is the performance of procurement biopsies.

METHODS

This is a retrospective study of 221 brain death donors with marginal kidneys transplanted in 223 recipients in Germany. Marginal kidneys were defined as kidneys with procurement biopsies done exceptionally to assess suitability for transplantation in otherwise potentially discarded organs. The impact of deceased donor AKI on patient survival and death-censored graft survival at 1, 3 and 5 years and graft function at 1 and 3 years after transplantation was investigated.

RESULTS

Recipients of kidneys with stage 3 AKI had a greater incidence of delayed graft function [DGF; OR_{Stage 1}: 1.435 (95% CI 0.438-0.702), OR_{Stage 2}: 2.463 (95% CI 0.656-9.245), OR_{Stage 3}: 4.784 (95% CI 1.421-16.101)] but a similar graft and patient survival compared to recipients of donors without AKI and with AKI stage 1 and 2 as well. The coexistence of recipient DGF and donor AKI was associated with the lowest graft survival and function rates.

CONCLUSION

The transplantation of deceased donor marginal kidneys with AKI confers a higher risk for DGF but is associated with acceptable graft and patient outcomes, which do not differ in comparison with marginal donor kidneys without AKI. Graft prognosis is especially poor if donor AKI and recipient DGF concur. Donor AKI was a risk factor independent of the histological lesions of procurement biopsies.

Applications of Transcriptomics in the Research of Antibody-Mediated Rejection in Kidney Transplantation: Progress and Perspectives

Antibody-mediated rejection (ABMR) is the major cause of chronic allograft dysfunction and loss in kidney transplantation. The immunological mechanisms of ABMR that have been featured in the latest studies indicate a highly complex interplay between various immune and nonimmune cell types. Clinical diagnostic standards have long been criticized for being arbitrary and the lack of accuracy. Transcriptomic approaches, including microarray and RNA sequencing of allograft biopsies, enable the identification of differential gene expression and the continuous improvement of diagnostics. Given that conventional bulk transcriptomic approaches only reflect the average gene expression but not the status at the single-cell level, thereby ignoring the heterogeneity of the transcriptome across individual cells, single-cell RNA sequencing is rising as a powerful tool to provide a high-resolution transcriptome map of immune cells, which allows the elucidation of the pathogenesis and may facilitate the development of novel strategies for clinical treatment of ABMR.

The Histological Spectrum and Clinical Significance of T Cell-mediated Rejection of Kidney Allografts

T cell-mediated rejection (TCMR) remains a significant cause of long-term kidney allograft loss, either indirectly through induction of donor-specific anti-HLA alloantibodies or directly through chronic active TCMR. Whether found by indication or protocol biopsy, Banff defined acute TCMR should be treated with antirejection therapy and maximized maintenance immunosuppression. Neither isolated interstitial inflammation in the absence of tubulitis nor isolated tubulitis in the absence of interstitial inflammation results in adverse outcomes, and neither requires antirejection treatment. RNA gene expression analysis of biopsy material may supplement conventional histology, especially in ambiguous cases. Lesser degrees of tubular and interstitial inflammation (Banff borderline) may portend adverse outcomes and should be treated when found on an indication biopsy. Borderline lesions on protocol biopsies may resolve spontaneously but require close follow-up if untreated. Following antirejection therapy of acute TCMR, surveillance protocol biopsies should be considered. Minimally invasive blood-borne assays (donor-derived cell-free DNA and gene expression profiling) are being increasingly studied as a means of following stable patients in lieu of biopsy. The clinical benefit and cost-effectiveness require confirmation in randomized controlled trials. Treatment of acute TCMR is not standardized but involves bolus corticosteroids with lymphocyte depleting antibodies for severe, refractory, or relapsing cases. Arteritis may be found with acute TCMR, active antibody-mediated rejection, or mixed rejections and should be treated accordingly. The optimal treatment ofchronic active TCMR is uncertain. Randomized controlled trials are necessary to optimally define therapy.

Serum uric acid as a risk factor for rejection after deceased donor kidney transplantation: A mono-institutional analysis of paired kidneys

Background

Deceased donor kidney transplantation (DDKT) is a major therapeutic option for patients with end-stage renal diseases. Although medical techniques improved in recent years, acute or chronic rejection after DDKT is not uncommon and often results in poor graft survival. Therefore, the determination of risk factors is very important to stratify patients and to improve outcomes. This study aims to evaluate the risk factors for treated rejection (TR) of patients after DDKT.

Methods

Clinical data of deceased donors and corresponding recipients were retrospectively collected. The primary outcome was TR defined as the treatment for rejection within 24 months after DDKT. Univariate comparisons of baseline characteristics were performed with Chi-square test, t-test, and Mann-Whitney U test. Logistic regression was constructed to analyze potential risk factors. Receiver operating characteristic (ROC) curve and Jordan index were generated to determine the optimal cutoff value. The association between continuous variables and TR was examined and visualized by using restricted cubic spline (RCS) models.

Results

Data of 123 deceased donors and 246 recipients were obtained and analyzed. The median age was 41 (4-62) years for recipients and 39 (1-65) years for donors. The recipients who died or suffered graft loss during the follow-up period were 8 (3.3%) and 12 (4.9%), respectively. After univariate analysis and subsequent multivariate analysis, the preoperative serum uric acid (OR, 2.242; 95% CI, 1.037-4.844; P = 0.040), platelet (OR, 2.163; 95% CI, 1.073-4.361, P = 0.031), absolute neutrophil count (OR, 2.183; 95% CI, 1.025-4.649; P = 0.043), and HLA-DQ mismatch (OR, 2.102; 95% CI, 1.093-4.043; P = 0.026) showed statistical significance. RCS models showed that patients with higher levels of uric acid had increased risk of TR.

Conclusions

Serum uric acid and other three indicators were found to be the independent risk factors for TR, which may contribute to stratify patients and develop personalized regimen in perioperative period.

Effect of pretransplant dialysis vintage on clinical outcomes in deceased donor kidney transplant

The waiting time for deceased donor kidney transplants (DDKT) is increasing. We evaluated DDKT prognosis according to the pretransplant dialysis vintage. A total of 4117 first-time kidney transplant recipients were enrolled from a prospective nationwide cohort in Korea. DDKT recipients were divided into tertiles according to pretransplant dialysis duration. Graft failure, mortality, and composite were compared between DDKT and living donor kidney transplant (LDKT) recipients. Pretransplant dialysis vintage was longer annually in DDKT recipients. In the subdistribution of the hazard model for the competing risk, the first tertile did not show an increased risk of graft failure compared with LDKT recipients; however, the second and third tertile groups had an increased risk of graft failure compared to LDKT recipients (adjusted hazard ratio [aHR] 3.59; 95% confidence interval [CI] 1.69-7.63; P < 0.001; aHR 2.37; 95% CI 1.06-5.33; P = 0.037). All DDKT groups showed a significantly higher risk of patient death than LDKT, with the highest risk in the third tertile group (aHR 11.12; 95% CI 4.94-25.00; P < 0.001). A longer pretransplant dialysis period was associated with a higher risk of the composite of patient death and graft failure in DDKT recipients. DDKT after a short period of dialysis had non-inferior results on graft survival compared with LDKT.

The Role of Innate Immune Cells in the Prediction of Early Renal Allograft Injury Following Kidney Transplantation

Background: Despite recent advances and refinements in perioperative management of kidney transplantation (KT), early renal graft injury (eRGI) remains a critical problem with serious impairment of graft function as well as short- and long-term outcome. Serial monitoring of peripheral blood innate immune cells might be a useful tool in predicting post-transplant eRGI and graft outcome after KT. Methods: In this prospective study, medical data of 50 consecutive patients undergoing KT at the University Hospital of Leipzig were analyzed starting at the day of KT until day 10 after the transplantation. The main outcome parameter was the occurrence of eRGI and other outcome parameters associated with graft function/outcome. eRGI was defined as graft-related complications and clinical signs of renal IRI (ischemia reperfusion injury), such as acute tubular necrosis (ATN), delayed graft function (DGF), initial nonfunction (INF) and graft rejection within 3 months following KT. Typical innate immune cells including neutrophils, natural killer (NK) cells, monocytes, basophils and dendritic cells (myeloid, plasmacytoid) were measured in all patients in peripheral blood at day 0, 1, 3, 7 and 10 after the transplantation. Receiver operating characteristics (ROC) curves were performed to assess their predictive value for eRGI. Cutoff levels were calculated with the Youden index. Significant diagnostic immunological cutoffs and other prognostic clinical factors were tested in a multivariate logistic regression model. Results: Of the 50 included patients, 23 patients developed eRGI. Mean levels of neutrophils and monocytes were significantly higher on most days in the eRGI group compared to the non-eRGI group after transplantation, whereas a significant decrease in NK cell count, basophil levels and DC counts could be found between baseline and postoperative course. ROC analysis indicated that monocytes levels on POD 7 (AUC: 0.91) and NK cell levels on POD 7 (AUC: 0.92) were highly predictive for eRGI after KT. Multivariable analysis identified recipient age (OR 1.53 (95% CI: 1.003−2.350), p = 0.040), recipient body mass index > 25 kg/m2 (OR 5.6 (95% CI: 1.36−23.9), p = 0.015), recipient cardiovascular disease (OR 8.17 (95% CI: 1.28−52.16), p = 0.026), donor age (OR 1.068 (95% CI: 1.011−1.128), p = 0.027), <0.010), deceased-donor transplantation (OR 2.18 (95% CI: 1.091−4.112), p = 0.027) and cold ischemia time (CIT) of the renal graft (OR 1.005 (95% CI: 1.001−1.01), p = 0.019) as clinically relevant prognostic factors associated with increased eRGI following KT. Further, neutrophils > 9.4 × 103/μL on POD 7 (OR 16.1 (95% CI: 1.31−195.6), p = 0.031), monocytes > 1150 cells/ul on POD 7 (OR 7.81 (95% CI: 1.97−63.18), p = 0.048), NK cells < 125 cells/μL on POD 3 (OR 6.97 (95% CI: 3.81−12.7), p < 0.01), basophils < 18.1 cells/μL on POD 10 (OR 3.45 (95% CI: 1.37−12.3), p = 0.02) and mDC < 4.7 cells/μL on POD 7 (OR 11.68 (95% CI: 1.85−73.4), p < 0.01) were revealed as independent biochemical predictive variables for eRGI after KT. Conclusions: We show that the combined measurement of immunological innate variables (NK cells and monocytes on POD 7) and specific clinical factors such as prolonged CIT, increased donor and recipient age and morbidity together with deceased-donor transplantation were significant and specific predictors of eRGI following KT. We suggest that intensified monitoring of these parameters might be a helpful clinical tool in identifying patients at a higher risk of postoperative complication after KT and may therefore help to detect and—by diligent clinical management—even prevent deteriorated outcome due to IRI and eRGI after KT.

Surgeon preimplantation macroscopic graft appraisal improves risk stratification of deceased kidney donors: a prospective study

BACKGROUND

Preimplantation scores assist with correct kidney graft allocation, but macroscopic graft features have never been evaluated in this scenario.

METHODS

We designed a graft appraisal questionnaire, assessed its reproducibility by comparing the senior and junior surgeon responses and evaluated which features can predict transplant outcomes in 202 patients transplanted from 144 donors at a tertiary center. We created new prediction models in combination with validated preimplantation scores. The primary outcome was graft loss or eGFR<30 mL/min/1.73 m² at six months and secondary outcomes were delayed graft function, early graft loss and graft function at six months.

RESULTS

Interrater correlation was very good for adherent perinephric fat (kappa=0.91) and acceptable for cortical surface roughness (kappa=0.51) and cortical color (kappa=0.47). Adherent perirenal fat (Odds ratio=4.77; 95% CI: 2.10-10.85) and surface roughness (OR=2.11, 95% CI: 1.25-3.58) were independent predictors of the primary outcome, improving the kidney donor risk index efficacy model (AUC 0.71 vs. 0.82, P≤0.001), while cortical color and adherent fat improved the Irish risk model for delayed graft function (AUC 0.76 vs. 0.82, P=0.03). We created nomograms to visually assess the risk of both endpoints.

CONCLUSIONS

Kidney graft macroscopic appraisal is reproducible between surgeons and can improve the accuracy of clinical preimplantational prediction scores.

The Relationship Between Health Literacy and Outcomes Before and After Kidney Transplantation

Limited health literacy (HL) is associated with decreased kidney function and death in patients with chronic kidney disease. Less is known about the impact of HL on kidney transplant (KT) outcomes. The aim of this study was to examine the relationship between HL and KT outcomes, including rates of waitlisting, healthcare utilization, acute rejection, renal allograft function, renal allograft failure, and death.

Methods

We performed a retrospective review of HL data previously collected at our center. HL was assessed in a convenience sample of consecutive, English-speaking patients age ≥18 y who were evaluated for KT at Mayo Clinic in Minnesota between June 2015 and March 2017 as part of a practice improvement feasibility project (n = 690). HL was assessed using the 4-item Brief Health Literacy Screening Tool modified for the outpatient KT evaluation process. The 4 items assess confidence completing forms, reading comprehension, and oral literacy.

Results

Overall, 30.4% of patients had limited or marginal HL. Patients with limited or marginal HL were less likely than those with adequate HL to be waitlisted for KT (hazard ratio = 0.62 and 0.69, respectively), even after adjusting for age, marital status, body mass index, Charlson comorbidity index, or dialysis dependency. Patient HL was not associated with post-KT healthcare utilization, acute rejection, or renal allograft function. Patients with limited or marginal HL appeared to experience a higher risk of renal allograft failure and post-KT death, but the number of events was small, and the relationship was statistically significant only for marginal HL.

Conclusions

Inadequate HL is common in KT candidates and independently associated with decreased waitlisting for KT. We observed no statistically significant relationship between HL and posttransplant outcomes in our cohort. Further efforts to improve communication in patients with inadequate HL may improve access to KT.

Impact of Glomerulitis on Long-term Outcomes After Kidney Transplantation

The Banff classification scheme provides a framework for interpreting transplant kidney biopsies and has undergone various updates in the past 2 decades especially related to antibody-mediated rejection. The clinical significance of early glomerulitis seen within 4 mo on protocol biopsies has received limited attention. We hypothesized that early glomerulitis seen on protocol biopsies will lead to significant adverse outcomes as assessed by histopathology and allograft outcome.

The Effect of Body Mass Index on the Degree of Renal Interstitial Fibrosis and Tubular Atrophy - A Retrospective Case-Control Study

Introduction

The degree of interstitial fibrosis and tubular atrophy (IFTA) seen on kidney biopsy has long been used to judge the chronicity of kidney disease to predict renal disease outcomes and prognosis. It is an essential component incorporated in many renal disease prognostic classification systems on the native and renal allograft. The impact of increased body mass index on the body metabolism, and the human vascular system, including the functional unit of the kidney, the nephron, is well-addressed in the literature. In this study, we focus on evaluating the degree of IFTA concerning the patient's body mass index (BMI).

Method

All the specimens of nephrectomies performed in King Abdulaziz University Hospital for adults from January 2010 to February 2021 were evaluated for this study. A total of 125 cases were selected for the study. The glass slides were pulled and assessed for the degree of IFTA. The demographic data, and the patient's BMI, were collected from the hospital records.

Results

Subjects with high BMI showed a 1.62 (OR: 1.62, 95% CI: 0.62, 4.22) and 1.52 (AOR: 1.52, 95% CI: 0.56, 4.13) increased risk of high IFTA score compared with those with normal BMI. This study has proved that only at a BMI of 25 or more will there be a measurable, independent effect on the degree of IFTA.

Conclusion

Although a small number of hospital-based populations limits this study, it could prove the increased severity of IFTA in patients with high BMI. Its result may act as a spark that will drive extensive population-based studies that more precisely delineate the relationship between BMI and the degree of IFTA on different levels.