Relationship of HLA‐DR Expression to Rejection and Mononuclear Cell Infiltration in Renal Allograft Biopsies

Importance of Follow-Up Biopsies in the Prediction of Renal Allograft Survival Following Polyomavirus-Associated Nephropathy

OBJECTIVES

Allograft biopsy is the gold standard for diagnosing polyomavirus-associated nephropathy. We aimed to establish the effects of histopathologic findings proposed by the Banff Polyomavirus Working Group on graft outcome. We also aimed to understand the clinical importance of follow-up biopsies for patients with polyomavirus-associated nephropathy.

MATERIALS AND METHODS

Our study included 22 patients with polyomavirus-associated nephropathy. All biopsies were classified according to the latest Banff Polyomavirus Working Group classification. Follow-up biopsies of all patients were evaluated in detail.

RESULTS

The mean interval between polyomavirus-associated nephropathy and transplant was 10 ± 1.6 months. Of 22 patients, biopsy revealed stage 1 in 3 (13.6%), stage 2 in 17 (77.3%), and stage 3 in 2 patients (9.1%). Fourteen patients (63.6%) had polyomavirus viral load 3, 5 (22.7%) had polyomavirus viral load 2, and 3 had polyomavirus viral load 1. Among patients included in analyses, 18.2% had antibody-mediated rejection and 27.2% had T-cell-mediated rejection simultaneously with polyomavirus-associated nephropathy. Graft loss increased with increasing polyomavirus-associated nephropathy class and polyomavirus viral load (P = .015 and P = .002, respectively). The mean time of graft survival decreased with increasing degree of tubulitis, interstitial inflammation, plasma infiltration, and neutrophil infiltration. Patients with interstitial fibrosis, glomerular polyoma, and cortical plus medullar involvement showed earlier graft loss. Follow-up biopsies showed that diffuse interstitial fibrosis or persistent inflam-mation negatively influenced graft loss.

CONCLUSIONS

The Banff Polyomavirus Working Group's schema significantly correlated with graft outcome. Early detection of polyomavirus-associated nephro-pathy and subsequent detection of persistent inflammation and interstitial fibrosis and tubular atrophy in follow-up biopsies and modification of immunosuppressive therapy can successfully prevent graft loss.

Bio-Engineered Scaffolds Derived from Decellularized Human Esophagus for Functional Organ Reconstruction

Esophageal reconstruction through bio-engineered allografts that highly resemble the peculiar properties of the tissue extracellular matrix (ECM) is a prospective strategy to overcome the limitations of current surgical approaches. In this work, human esophagus was decellularized for the first time in the literature by comparing three detergent-enzymatic protocols. After decellularization, residual DNA quantification and histological analyses showed that all protocols efficiently removed cells, DNA (<50 ng/mg of tissue) and muscle fibers, preserving collagen/elastin components. The glycosaminoglycan fraction was maintained (70–98%) in the decellularized versus native tissues, while immunohistochemistry showed unchanged expression of specific ECM markers (collagen IV, laminin). The proteomic signature of acellular esophagi corroborated the retention of structural collagens, basement membrane and matrix–cell interaction proteins. Conversely, decellularization led to the loss of HLA-DR expression, producing non-immunogenic allografts. According to hydroxyproline quantification, matrix collagen was preserved (2–6 µg/mg of tissue) after decellularization, while Second-Harmonic Generation imaging highlighted a decrease in collagen intensity. Based on uniaxial tensile tests, decellularization affected tissue stiffness, but sample integrity/manipulability was still maintained. Finally, the cytotoxicity test revealed that no harmful remnants/contaminants were present on acellular esophageal matrices, suggesting allograft biosafety. Despite the different outcomes showed by the three decellularization methods (regarding, for example, tissue manipulability, DNA removal, and glycosaminoglycans/hydroxyproline contents) the ultimate validation should be provided by future repopulation tests and in vivo orthotopic implant of esophageal scaffolds.

BK Virus-Associated Nephropathy with Plasma Cell-Rich Infiltrates Treated by Bortezomib-Based Regimen

BK virus infection accompanied with plasma cell-rich infiltrates is a dilemma in renal transplant recipients. One young female patient diagnosed as BK virus-associated nephropathy with plasma cell-rich infiltrates at 16 months after renal transplant was treated with bortezomib and a sequential immuno-suppressive protocol of tacrolimus combined with leflunomide. After a short period of reduction, her serum creatinine increased slowly with stable BK viruria. The patient underwent repeat biopsy. The histologic changes showed a decrease in plasma cells and CD20+ cells in the allograft, but the other mononuclear cells showed no difference from the first biopsy. The immunosuppressive protocol was converted to tacrolimus combined with enteric-coated mycophenolate sodium. Her serum creatinine decreased gradually during 6 months of follow-up. We speculate that bortezomib can be used in BK virus-associated nephropathy accompanied with plasma cell-rich infiltrates, and this effect might be mediated through a decrease of plasma cells and CD20+ cells in the allograft. The dosage and time of therapy need to be explored in the future; additional studies of large samples are needed.

A four-year pathology review of the near total face transplant

In December of 2008, our institution performed a near total face transplant. The patient was monitored for signs of rejection assessed by paired skin and mucosa biopsies. The results of histological review of 120 biopsies collected during the first 4 years posttransplant are discussed. All biopsies were stained with hematoxylin and eosin, periodic acid-Schiff, immunohistochemical and TUNEL assays and graded using the Banff 2007 classification. Grade III rejection was diagnosed clinically at weeks 45 and 66, posttransplant; week 45 was determined as folliculitis while the erythema episode at week 66 confirmed an acute rejection (AR) that required hospitalization. The mucosa frequently showed interface inflammation without clinical signs of rejection and was not present in skin biopsies. In all, 34 of the 45 mucosal biopsies (75%) showed these interface changes. Clinical symptoms concurred with skin pathology in two grade III rejections. The mucosa showed histologic signs of rejection more frequently, which may indicate: increased mucosal sensitivity to rejection, a different type or subtype of AR that is specific to the mucosa, or a nonspecific process such as a drug effect. With more data and world experience, the diagnosis of face transplant rejection will be better defined and the Banff classification enhanced.

Plasmapheresis adjusts inflammatory responses in potential kidney transplant recipients

BACKGROUND

Plasmapheresis (PP) has been used in the treatment of various immunologic disorders, and its efficacy has mainly been attributed to the removal of humoral factors and autoantibodies. Besides these effects, PP may induce modifications of the cellular immunologic status, contributing to the restoration of impaired immunologic function. The effect of PP on lymphocyte subpopulations, plasma neopterin, and cytokines in renal transplant recipients was investigated in this study.

METHODS

We compared pre-PP and post-PP lymphocyte subpopulations and plasma neopterin in 37, and cytokine plasma levels in 30, potential renal transplant recipients. Plasma neopterin and cytokines were measured by enzyme-linked immunosorbent assay kits, lymphocyte subsets were determined using four-color fluorescence flow cytometry.

RESULTS

Lymphocyte subpopulation counts and ratios including CD45:μL (P=0.005), CD3:μL (P=0.02), CD4DR:μL (P=0.002), CD8:μL (P=0.01), and CD8DR:μL (P=0.005) T cells; CD4DR:CD4 (P=0.009) and CD8DR:CD8 (P=0.0004) ratios; DR cells:μL (P=0.003); CD19 B lymphocytes:μL (P=0.001); and plasma levels of neopterin (P<;0.0001), soluble interleukin-1 receptor antagonist (P<;0.0001), IL-8 (P=0.0001), and tumor necrosis factor-α (P=0.008) were significantly decreased after PP as compared with before PP. The results indicate a decrease of activated DR, CD4, and CD8 T lymphocytes and B lymphocytes, and a decrease of monocyte and macrophage activation as a result of PP.

CONCLUSION

Based on these results, we conclude that PP not only removes antibodies from the plasma but, in addition, modulates T-lymphocyte activation and the inflammatory response by decreasing plasma proinflammatory cytokines.

Urinary soluble HLA-DR is a potential biomarker for acute renal transplant rejection

BACKGROUND.: Urine is a potentially rich source of biomarkers for monitoring kidney dysfunction. In this study, we have investigated the potential of soluble human leukocyte antigen (sHLA)-DR in the urine for noninvasive monitoring of renal transplant patients. METHODS.: Urinary soluble HLA-DR levels were measured by sandwich enzyme-linked immunosorbent assay in 103 patients with renal diseases or after renal transplantation. sHLA-DR in urine was characterized by Western blotting and mass spectrometry. RESULTS.: Acute graft rejection was associated with a significantly elevated level of urinary sHLA-DR (P<0.0001), compared with recipients with stable graft function or healthy individuals. A receiver operating characteristic curve analysis showed the area under the curve to be 0.88 (P<0.001). At a selected threshold, the sensitivity was 80% and specificity was 98% for detection of acute renal transplant rejection. sHLA-DR was not exosomally associated and was of lower molecular weight compared with the HLA-DR expressed as heterodimer on the plasma membrane of antigen-presenting cells. CONCLUSIONS.: sHLA-DR excreted into urine is a promising indicator of renal transplant rejection.

BK virus nephritis after renal transplantation

BK virus nephritis is an increasing problem and is posing a threat to improving renal transplant graft survival. The pathogenesis of this condition remains to be investigated. Higher prevalence of BK virus infection in recent years has been correlated with declining acute rejection rates and the use of potent immunosuppressive agents. Patients with this infection usually have asymptomatic viremia and/or nephritis with or without worsening of renal function. The diagnosis of this disease is based on detecting the virus or its effects in urine, blood, and renal tissue. In the past, approximately 30 to 60% of patients with BK virus nephritis developed graft failure. In recent years, the combination of early detection, prompt diagnosis, and therapies including preventive measures have resulted in better outcomes.

Molecular evidence of injury and inflammation in normal and fibrotic renal allografts one year posttransplant

INTRODUCTION

Factors contributing to kidney transplant fibrosis remain incompletely understood, particularly in the absence of acute complications.

METHODS

Baseline and 1-year surveillance biopsies from 15 uncomplicated living donor kidney transplants were subjected to microarray and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses to examine changes in gene expression patterns over time. Biopsy pairs were purposefully selected from allografts with no history of acute complications and were divided into those that were histologically normal (n=7) and those that had developed subclinical interstitial fibrosis (n=8) at 1 year.

RESULTS

Compared with the paired baseline specimens, expression levels of 3578 probesets were found altered in all the 1-year biopsies studied. A large proportion of the up-regulated genes in this transplant-associated profile were functionally linked with inflammation, immunity, or response to injury. These included components of inflammation-related signaling pathways (integrin, interferon, and Toll-like receptor) as well as individual mediators of inflammatory and immune responses. An additional 2884 probesets demonstrated altered expression in fibrotic grafts only at 1 year. The gene products in this fibrosis-associated profile also were predominantly linked with inflammation and immune function, suggesting exaggerated inflammatory activity within the fibrotic grafts. qRT-PCR analyses confirmed the predicted expression patterns for selected transcripts from the microarray profiles.

CONCLUSIONS

Transcriptional profiles of histologically normal living donor renal allografts indicate that there is ongoing injury response and inflammation at 1 year compared to the immediate posttransplant period. Subclinical development of interstitial fibrosis during the first posttransplant year is associated with additional up-regulation of inflammation-related genes.