Chronic Kidney Transplant Rejection Research Articles

The role of regulatory T cells in the pathogenesis of acute kidney injury.

The incidence of acute kidney injury (AKI) is on the rise and is associated with high mortality; however, there are currently few effective treatments. Moreover, the relationship between Tregs and other components of the immune microenvironment (IME) in the pathogenesis of AKI remains unclear. We downloaded four publicly accessible AKI datasets, GSE61739, GSE67401, GSE19130, GSE81741, GSE19288 and GSE106993 from the gene expression omnibus (GEO) database. Additionally, we gathered two kidney single-cell sequencing (scRNA-seq) samples from the Department of Organ Transplantation at Zhujiang Hospital of Southern Medical University to investigate chronic kidney transplant rejection (CKTR). Moreover, we also collected three samples of normal kidney tissue from GSE131685. By analysing the differences in immune cells between the AKI and Non-AKI groups, we discovered that the Non-AKI group contained a significantly greater number of Tregs than the AKI group. Additionally, the activation of signalling pathways, such as inflammatory molecules secretion, immune response, glycolytic metabolism, NOTCH, FGF, NF-κB and TLR4, was significantly greater in the AKI group than in the Non-AKI group. Additionally, analysis of single-cell sequencing data revealed that Tregs in patients with chronic kidney rejection and in normal kidney tissue have distinct biology, including immune activation, cytokine production, and activation fractions of signalling pathways such as NOTCH and TLR4. In this study, we found significant differences in the IME between AKI and Non-AKI, including differences in Tregs cells and activation levels of biologically significant signalling pathways. Tregs were associated with lower activity of signalling pathways such as inflammatory response, inflammatory molecule secretion, immune activation, glycolysis.

Tackling Chronic Kidney Transplant Rejection: Challenges and Promises.

Despite advances in post-transplant management, the long-term survival rate of kidney grafts and patients has not improved as approximately forty percent of transplants fails within ten years after transplantation. Both immunologic and non-immunologic factors contribute to late allograft loss. Chronic kidney transplant rejection (CKTR) is often clinically silent yet progressive allogeneic immune process that leads to cumulative graft injury, deterioration of graft function. Chronic active T cell mediated rejection (TCMR) and chronic active antibody-mediated rejection (ABMR) are classified as two principal subtypes of CKTR. While significant improvements have been made towards a better understanding of cellular and molecular mechanisms and diagnostic classifications of CKTR, lack of early detection, differential diagnosis and effective therapies continue to pose major challenges for long-term management. Recent development of high throughput cellular and molecular biotechnologies has allowed rapid development of new biomarkers associated with chronic renal injury, which not only provide insight into pathogenesis of chronic rejection but also allow for early detection. In parallel, several novel therapeutic strategies have emerged which may hold great promise for improvement of long-term graft and patient survival. With a brief overview of current understanding of pathogenesis, standard diagnosis and challenges in the context of CKTR, this mini-review aims to provide updates and insights into the latest development of promising novel biomarkers for diagnosis and novel therapeutic interventions to prevent and treat CKTR.

Single-cell analysis reveals immune landscape in kidneys of patients with chronic transplant rejection.

Rationale: Single-cell RNA sequencing (scRNA-seq) has provided an unbiased assessment of specific profiling of cell populations at the single-cell level. Conventional renal biopsy and bulk RNA-seq only average out the underlying differences, while the extent of chronic kidney transplant rejection (CKTR) and how it is shaped by cells and states in the kidney remain poorly characterized. Here, we analyzed cells from CKTR and matched healthy adult kidneys at single-cell resolution.Methods: High-quality transcriptomes were generated from three healthy human kidneys and two CKTR biopsies. Unsupervised clustering analysis of biopsy specimens was performed to identify fifteen distinct cell types, including major immune cells, renal cells and a few types of stromal cells. Single-sample gene set enrichment (ssGSEA) algorithm was utilized to explore functional differences between cell subpopulations and between CKTR and normal cells.Results: Natural killer T (NKT) cells formed five subclasses, representing CD4+ T cells, CD8+ T cells, cytotoxic T lymphocytes (CTLs), regulatory T cells (Tregs) and natural killer cells (NKs). Memory B cells were classified into two subtypes, representing reverse immune activation. Monocytes formed a classic CD14+ group and a nonclassical CD16+ group. We identified a novel subpopulation [myofibroblasts (MyoF)] in fibroblasts, which express collagen and extracellular matrix components. The CKTR group was characterized by increased numbers of immune cells and MyoF, leading to increased renal rejection and fibrosis.Conclusions: By assessing functional differences of subtype at single-cell resolution, we discovered different subtypes that correlated with distinct functions in CKTR. This resource provides deeper insights into CKTR biology that will be helpful in the diagnosis and treatment of CKTR.

Steroid regulation: An overlooked aspect of tolerance and chronic rejection in kidney transplantation.

Steroid conversion (HSD11B1, HSD11B2, H6PD) and receptor genes (NR3C1, NR3C2) were examined in kidney-transplant recipients with "operational tolerance" and chronic rejection (CR), independently and within the context of 88 tolerance-associated genes. Associations with cellular types were explored. Peripheral whole-blood gene-expression levels (RT-qPCR-based) and cell counts were adjusted for immunosuppressant drug intake. Tolerant (n = 17), stable (n = 190) and CR patients (n = 37) were compared. Healthy controls (n = 14) were used as reference. The anti-inflammatory glucocorticoid receptor (NR3C1) and the cortisol-activating HSD11B1 and H6PD genes were up-regulated in CR and were lowest in tolerant patients. The pro-inflammatory mineralocorticoid gene (NR3C2) was downregulated in stable and CR patients. NR3C1 was associated with neutrophils and NR3C2 with T-cells. Steroid conversion and receptor genes, alone, enabled classification of tolerant patients and were major contributors to gene-expression signatures of both, tolerance and CR, alongside known tolerance-associated genes, revealing a key role of steroid regulation and response in kidney transplantation.

Sirolimus: A Switch Option for Mycophenolate Mofetil–Induced Leukopenia in Renal Transplant Recipients

Mycophenolate mofetil (MMF) is a potent immunosuppressive agent used to prevent acute and chronic rejection in kidney transplantation or for rescue therapy. One side effect of MMF is bone marrow toxicity, including leukopenia, which may necessitate drug withdrawal. We report 2 patients who underwent kidney transplantation and developed leukopenia while receiving MMF and safely switched to sirolimus. A 35-year-old woman underwent deceased donor kidney transplantation. She received basiliximab, tacrolimus, MMF, and a corticosteroid. On postoperative day (POD) 75, her white blood cell (WBC) count was 1800/μL. A 44-year-old women underwent deceased donor kidney transplantation and received basiliximab, tacrolimus, MMF, valganciclovir, and a corticosteroid. On POD 88, her WBC count was 1320/μL. MMF was switched to sirolimus, resulting in recovery of WBC count without rejection. Switch from MMF to sirolimus is safe and favorable in MMF-induced leukopenia in renal transplant recipient.

The KUPKB: a novel Web application to access multiomics data on kidney disease

The information gathered from the large number of omics experiments in renal biology is underexplored, as it is scattered over many publications or held in supplemental data. To address this, we have developed an open-source Kidney and Urinary Pathway Knowledge Base (KUPKB) that facilitates simple exploration of these omics data. The KUPKB currently comprises 220 data sets (miRNA, mRNA, proteins, and metabolites) extracted from existing publications or databases. Researchers can explore the integrated data using the iKUP browser, and a simple template is provided to submit new omics data sets to the knowledge base. As an example of iKUP's use, we show how we identified, in silico, calreticulin as a protein induced in human interstitial fibrosis and tubular atrophy (IFTA) in chronic kidney transplant rejection; a link that would have been difficult to establish using existing Web-based tools. Using immunohistochemistry, we validated in vivo this in silico result in human and rat biopsies of IFTA, thus identifying calreticulin as a potential new player in chronic kidney transplant rejection. The KUPKB provides a simple tool that enables users to quickly survey a wide range of omics data sets and has been shown to facilitate rapid hypothesis generation in the context of renal pathophysiology.

Contrasting roles of donor and recipient TGFB1 and IFNG gene polymorphic variants in chronic kidney transplant rejection.

To assess the long-term impact (minimum of 3 years follow-up) of polymorphisms in cytokine genes in donor:recipient pairs on the results of the transplant. We compared genetic cytokine polymorphisms and the primary factors of risk for the development of chronic rejection in paired groups of renal transplant patients with and without chronic allograft nephropathy [CAN]. Multivariate analysis indicated that the presence of the high-production TT genotype (codon 10) of the transforming growth factor beta-1 (TGFB1) was protective in receptors (p=0.017), contrasting with the increased risk when present in donor samples (p=0.049). On the other hand, in the case of the gamma interferon studied, the greater frequency of the high production allele was protective in the analysis of the donor group (p=0.013), increasing the risk of chronic nephropathy of the allograft when present in the recipients (p=0.036). Our results highlight the importance of TGFB1 genotyping in donors, and indicate that polymorphisms in the gene of this cytokine in donor cells might contribute to the development of chronic allograft nephropathy.

Urinary Tract Infections in Solid Organ Transplant Recipients

Urinary Tract Infections in Solid Organ Transplant Recipients

IMPACT OF FEBRILE INFECTIONS ON THE LONG-TERM FUNCTION OF KIDNEY ALLOGRAFTS

We prospectively determined the impact of febrile infectious disease on long-term renal graft function compared with a matched control group. Included in our study were 39 patients who presented with episodes of febrile infection with body temperature greater than 38C on 2 consecutive occasions, necessitating hospitalization. In addition, 39 controls without febrile infection requiring hospitalization within 2 months were chosen from the complete data pool of all renal transplant recipients followed at our transplant clinic using the matched pair technique. Renal function was estimated by serum creatinine and calculated creatinine clearance. Of the 39 patients with infection 15 had urinary tract infection and 24 had other, mostly bacterial infection, including pneumonia/severe bronchitis in 12, oral/dental infection in 2, gastroenteritis in 2, shunt sepsis in 1, herpes zoster in 1, cytomegalovirus in 1 and other in 5. Mean estimated creatinine clearance plus or minus standard deviation was similar in the infection and control groups at the beginning of the study (51 +/- 22 and 51 +/- 23 ml. per minute, respectively). During the infectious episode mean creatinine clearance significantly decreased to 38 +/- 17 ml. per minute in the infection group. After infection resolved creatinine clearance returned to an almost baseline mean value of 50 +/- 23 ml. per minute. However, after 2 years of followup there was a significant difference in mean creatinine clearance in the infection group versus controls (45 +/- 25 versus 52 +/- 25 ml. per minute, p = 0.022). To our knowledge we have shown for the first time in a prospective controlled study that febrile infectious episodes correlate with poor long-term renal graft function.

Urinary F2-isoprostanes formation in kidney transplantation.

Oxygen free-radical mediated lipid peroxidation has been implicated in many diseases such as chronic renal failure, hemodialysis and chronic kidney transplant rejection. However, insight into the role of free radical generation in kidney transplantation has been constrained by the limitations of current indexes of oxidant stress in vivo. Isoprostaglandin F2alpha type-III (iPF2alpha-III, formerly known as 8-iso-prostaglandin F2alpha) is emerging as a reliable marker of oxidant stress in vivo. The purpose of our study was to investigate iPF2alpha-III formation as an index of lipid peroxidation in the 5 d following kidney transplantation. Urinary iPF2alpha-III measurements were performed by enzyme immunoassay from day I to 5 in 11 patients undergoing kidney transplantation. Results were compared with 11 healthy volunteers matched in sex, age and cigarette smoking. Urinary excretion of iPF2alpha-III at day 1 did not significantly differ between control and transplant group (111 +/- 17 vs. 92 +/- 10 pM/ mM creatinine, respectively, NS). Urinary iPF2alpha-III levels did not differ between day 1 to 5, and were not correlated to cold ischaemia time. Our study shows no evidence of enhanced lipid peroxidation in the first 5 d following kidney transplantation.

Transplant glomerulopathy as a cause of late graft loss

Several pathophysiological processes contribute to chronic kidney transplant rejection. Among the most distinctive is transplant glomerulopathy, characterized by widening of the subendothelial space with accumulation of flocculent material and duplication of the basement membrane. The current study assessed the course of graft loss in patients with and without this form of injury. Twenty-five patients with prominent transplant glomerulopathy were identified from biopsies performed at a single center during 4 years. These patients were compared with control patients with a similar degree of renal dysfunction in whom biopsies showed chronic rejection without transplant glomerulopathy. Patients with transplant glomerulopathy showed an increased rate of graft loss after biopsy. Biopsies were performed longer after transplantation in these patients, however, than in control patients with an equal degree of graft dysfunction. Graft survival from the time of transplantation was therefore not different between the two groups. Morphological studies showed that transplant glomerulopathy was not associated with increased severity of chronic vascular injury characterized by arterial and arteriolar intimal thickening or hyalinosis. These findings show that transplant glomerulopathy may develop late after transplantation and separately from chronic vascular rejection. The appearance of transplant glomerulopathy on a biopsy specimen is followed by accelerated graft loss.

The association between acute rejection and chronic rejection in kidney transplantation

The association between acute rejection and chronic rejection in kidney transplantation

Removal of anti-donor antibody by double-filtration plasmapheresis to prevent chronic rejection in kidney transplantation

Removal of anti-donor antibody by double-filtration plasmapheresis to prevent chronic rejection in kidney transplantation

Down-regulation of glomerular matrix metalloproteinase-2 gene in human NIDDM

Regulation of mesangial matrix deposition is a dynamic phenomenon involving synthetic and degradative processes. The latter involve a number of matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinases (TIMP). Experimental studies suggest that mesangial matrix degradation is inhibited in diabetic nephropathy, and that this phenomenon has a pathogenic role. The expression of genes for MMP2 and TIMP2 in human diabetic nephropathy was investigated. Reverse transcription polymerase chain reaction was carried out in microdissected glomeruli and tubulo-interstitium obtained from kidney biopsies. We studied 16 NIDDM patients, 5 patients with glomerulonephritis or chronic kidney transplant rejection, and 5 normal control subjects. Albumin excretion rate and renal histology for NIDDM patients were available. Contrary to TIMP2 which was expressed both in tubulo-interstitium and glomeruli in almost all renal biopsies, MMP2 gene down-regulation was observed in glomeruli from all NIDDM patients, irrespective of the albumin excretion rate, and of renal histology. In contrast, this gene was expressed in biopsies from other subjects (chi(2) = 20.6; p = 0.000). In conclusion, this study demonstrates that: 1) in glomeruli of NIDDM patients the MMP2 gene is down-regulated; 2) in biopsies of NIDDM patients the MMP2/TIMP2 pattern is peculiar for NIDDM; 3) the MMP2 gene down-regulation is observed in all NIDDM patients, irrespective of the level of albuminuria and of renal histology. MMP2 gene down-regulation seems to be a molecular epiphenomenon of diabetes, rather than a marker of diabetic nephropathy.

Postoperative production of anti-donor antibody and chronic rejection in renal transplantation.

To study the relevance of anti-donor antibody (ADA) to chronic rejection in kidney transplantation, we retrospectively examined the long-term kinetics of ADA by flow cytometric analysis. Among 537 recipients who underwent living-donor kidney transplantation between 1986 and 1994, 29 patients with chronic rejection (CR group) and 33 patients with stable graft function (ST group) were randomly selected for analysis. Patient serum taken 1 or 2 days before transplantation, serum taken 1 month after transplantation, and the most current serum were analyzed for the presence of ADA to donor T and B cells. In the CR group, IgG antibody to donor B cells of the most current serum was positive in 25 of 29 patients, whereas it was positive in only 5 patients in the ST group P<0.001. The mean fluorescent intensity of the antibody was also significantly higher in the CR group than that in ST group P<0.01. In contrast, IgG antibody to donor T cells of the most current serum was positive in only five patients in the CR group. No significant difference was observed in the pretransplant and 1-month posttransplant sera between the CR and ST groups. We conclude that the posttransplant production of IgG antibody to donor B cells seemed to be highly relevant to chronic rejection.

Treatment of chronic kidney transplant rejection with prostacyclin — reduction of platelet deposition in the transplant; Prolongation of platelet survival and improvement of transplant function

8 patients with chronic kidney transplant rejection were treated intravenously with prostacyclin during 5 days. This treatment seemed to have a beneficial effects as measured by platelet deposition in the transplant and prolongation of platelet survival. In the majority of cases the transplant function improved. A longer duration of this therapeutic effect could be a new way for the long-term treatment of chronic kidney transplant rejection.