Chronic Renal Allograft Rejection Research Articles

306.4: T cell-derived IL17 orchestrating macrophages infiltration in chronic renal allograft rejection.

306.4: T cell-derived IL17 orchestrating macrophages infiltration in chronic renal allograft rejection.

Gene Expression and Functional Analysis in Patients with Acute and Chronic Renal Allograft Rejection

Kidney transplantation is the therapy of choice for patients with end-stage kidney disease (ESKD). Nevertheless, the main limitation for long-term graft survival is immune-mediated rejection. Some authors have proposed that differences in immune effector mechanisms are influenced by underlying molecular mechanisms; thereby, the identification of differentially expressed genes in acute or chronic rejection in non-invasive samples such as urine may be essential for the identification of potential biomarkers and biological processes associated with allograft outcomes. Our aim was to explore differences in gene expression and functional categories associated with acute and chronic kidney rejection in blood, biopsy, and urine of kidney transplant patients using RNA-Seq. RNA was isolated and sequenced implementing standard protocols. Analyses were addressed to identify differentially expressed genes (DEGs) and Functional Categories of Gene Ontology comparing between samples. Then we focused on immune genes and pathways to identify their association with the allograft. We identified a significant transcriptional similarity between biopsy and urine, in comparison with blood in acute and chronic rejection. Functional analyses suggested an enrichment of immune processes such as antigen processing and presentation, and regulation of B cell receptor signaling pathway in blood of acute and chronic rejection, respectively. Additionally, we observed an increase in expression of chemokines in biopsy and urine of both outcomes along with an increase in chemokine receptors in blood. Our findings suggest that urine is suitable for identifying potential biomarkers and biological processes related to renal allograft rejection, as it shares a significant number of regulated genes with biopsy.

Co-inhibition of immunoproteasome subunits LMP2 and LMP7 enables prevention of transplant arteriosclerosis.

The loss of vascular wall cells in allotransplanted arteries is the initial event leading to transplant arteriosclerosis (TA) and ensuing loss of allograft function. Pharmacological agents able to prevent TA are currently lacking. We previously showed that selective inhibition of the immunoproteasome prevented the chronic rejection of renal allografts. However, the role and mechanisms of selective inhibition of a single immunoproteasome subunit to prevent immune-mediated vascular allograft rejection and TA is not clear. The effect and potential mechanism of combined or individual inhibition of peptidolytically active immunoproteasome LMP7 (β5i) and LMP2 (β1i) subunits on immune rejection-mediated TA was investigated using the epoxyketone inhibitor ONX 0914, and the recently developed LMP7-selective inhibitor KZR-329 and LMP2-selective inhibitor KZR-504 in a rat aorta transplantation model. We find that co-inhibition of LMP7 and LMP2 in allogeneic recipients significantly suppressed T-cell activation and function by expressing inhibitory surface markers and then activating inhibitory signals. Moreover, co-inhibition of LMP7 and LMP2 substantially reduced the number of immunoglobulin G-secreting cells and plasma cells and production of alloantibodies through activating the unfolded protein response and incapacitating the survival niche of plasma cells in the bone marrow. Consequentially, the accumulation of inflammatory cytokines, complement, and antibodies is reduced and the apoptosis of vascular wall cells decreased in aortic allografts via LMP7 and LMP2 co-inhibition with ONX 0914 treatment or combined KZR-329 and KZR-504 treatment. However, neither individual inhibition of LMP7 by KZR-329 nor individual inhibition of LMP2 by KZR-504 showed suppression of immune rejection and TA. We define a critical role of LMP7 and LMP2 in TA and strongly propose co-inhibition of both immunoproteasome subunits as promising therapeutic approach to suppress TA and allograft rejection.

The first experience of cord blood stem cells application in kidney transplantation: A descriptive study

Abstract. Kidney transplantation is recognized as the optimal method of end-stage kidney disease treatment, but chronic renal allograft rejection remains an unresolved issue and leads to transplanted organ function loss. Recent studies show positive effects of stem cell injections in a variety of diseases, including kidney transplantation.
 The present study aimed to analyze the first experience of umbilical cord blood stem cells application in living-related kidney transplantation in Shalimov’s National Institute of Surgery and Transplantation, give a preliminary assessment of their effectiveness and safety, evaluate the clinical course and especially the dynamics of laboratory parameters in the recipient’s postoperative period.
 Methods. The study group included 6 male, adult recipients of kidney transplants, who performed the first kidney allotransplantation from a living family donor in the Shalimov’s National Institute of Surgery and Transplantology in 2020 – 2021. Before surgery, all patients received intravenous administration of a fraction of nuclear cells from human umbilical cord blood at a dose of 2-3 x 106/kg body weight in combination with standard three-component immunosuppressive therapy. Immune system studies were performed before kidney transplantation, on the first and third days of the postoperative period, at the end of the first and second week, as well as on the first, third, sixth, and twelfth months, following kidney transplantation. Renal graft function was assessed by serum creatinine and glomerular filtration rate. Monitoring of clinical and laboratory parameters of blood and urine, the concentration of calcineurin inhibitors (C0) was carried out regularly three times a week for the first month, twice a month for 2-3 months, and once a month until the end of the year.
 Puncture biopsy of the transplanted kidney was performed three months after surgery to diagnose the pathology of the graft, namely the manifestations of acute and chronic rejection, the nature and degree of which were determined according to the Banff classification.
 The state of the immune system of the recipients was characterized by indicators of cellular and humoral immunity.
 Statistical processing of research results was performed using the statistical package StatSoft (2010) STATISTICA 9.1 for Windows StatSoft Inc, Tusla.
 Results. All patients received cord blood stem cells without complications. On the first day after surgery, an average diuresis was 9415 ± 928.1 ml. Normalization of graft function was observed on the second or third day (GFR more than 90 ml/ min/1.73 m2). There were no rejections of grafts and signs of opportunistic infections in the patients during 1 year follow-up period. Morphological studies did not reveal signs of significant pathological changes in transplanted kidneys in patients who received stem cells as induction therapy.
 The study of the state of the immune system of recipients in the dynamics, given the insufficient number of patients, requires further research.
 Conclusions. The administration of cord blood stem cells to recipients prior to kidney transplantation is safe and promotes rapid recovery of renal allograft function. There were no signs of morphological proven chronic graft rejection, which allows us to predict its long-term functioning in the future. To assess the response of the recipient's immune system to the application of cord blood stem cells requires the accumulation of additional data.

Does the cytomegalovirus infection cause kidney transplant rejection in Erbil city patients, Kurdistan region of Iraq?

Does the cytomegalovirus infection cause kidney transplant rejection in Erbil city patients, Kurdistan region of Iraq?

A Rat Orthotopic Renal Transplantation Model for Renal Allograft Rejection.

Renal allograft rejection limits the long-term survival of patients after renal transplantation. Rat orthotopic renal transplantation is an essential model to investigate the mechanism of renal allograft rejection in pre-clinical studies and could aid in the development of novel approaches to improve the long-term survival of renal allografts. Donor kidney implantation in rat orthotopic renal transplantation is commonly performed by end-to-side anastomosis to recipients' aorta and inferior vena cava. In this model, the donor's kidney was implanted using end-to-end anastomosis to the recipients' renal artery and renal vein. The donor's ureter was anastomosed to the recipient's bladder in an end-to-side 'tunnel' method. This model contributes to better healing of ureter-bladder anastomosis and increases the recipients' survival by avoiding interference with blood supply and venous reflux of the lower body. This model can be used to investigate the mechanisms of acute and chronic immune and pathologic rejection of renal allografts. Here, the study describes the detailed protocols of this orthotopic renal transplantation between rats.

Diffusion-Weighted Imaging and Mapping of T1 and T2 Relaxation Time for Evaluation of Chronic Renal Allograft Rejection in a Translational Mouse Model.

We hypothesized that multiparametric MRI is able to non-invasively assess, characterize and monitor renal allograft pathology in a translational mouse model of chronic allograft rejection. Chronic rejection was induced by allogenic kidney transplantation (ktx) of BALB/c-kidneys into C57BL/6-mice (n = 23). Animals after isogenic ktx (n = 18) and non-transplanted healthy animals (n = 22) served as controls. MRI sequences (7T) were acquired 3 and 6 weeks after ktx and quantitative T1, T2 and apparent diffusion coefficient (ADC) maps were calculated. In addition, in a subset of animals, histological changes after ktx were evaluated. Chronic rejection was associated with a significant prolongation of T1 time compared to isogenic ktx 3 (1965 ± 53 vs. 1457 ± 52 ms, p < 0.001) and 6 weeks after surgery (1899 ± 79 vs. 1393 ± 51 ms, p < 0.001). While mean T2 times and ADC were not significantly different between allogenic and isogenic kidney grafts, histogram-based analysis of ADC revealed significantly increased tissue heterogeneity in allografts at both time points (standard derivation/entropy/interquartile range, p < 0.05). Correspondingly, histological analysis showed severe inflammation, graft fibrosis and tissue heterogeneity in allogenic but not in isogenic kidney grafts. In conclusion, renal diffusion weighted imaging and mapping of T2 and T1 relaxation times enable detection of chronic renal allograft rejection in mice. The combined quantitative assessment of mean values and histograms provides non-invasive information of chronic changes in renal grafts and allows longitudinal monitoring.

Визначення рівня субпопуляцій лімфоцитів периферичної крові для діагностики хронічної реакції відторгнення ниркових алотрансплантатів

Актуальність. Однією з основних причин втрат ниркових алотрансплантатів (НАТ) у віддалені строки після трансплантації є прогресуюча хронічна дисфункція ниркового алотрансплантата (ХДНА), причиною розвитку якої в 20–60 % випадків є хронічне відторгнення (ХВ). Діагностика причин дисфункції трансплантата базується на морфологічному дослідженні, яке через інвазивність має ряд недоліків. Тому великий інтерес являє пошук неінвазивних методів діагностики стану НАТ, зокрема, дослідження клітинної ланки імунної відповіді. Мета. Дослідження відносної кількості субпопуляцій лімфоцитів периферичної крові та їх співвідношення в реципієнтів у віддаленому періоді після трансплантації нирки, оцінювання інформативності цих показників для діагностики ХВ НАТ. Матеріали та методи. Досліджено рівні субпопуляцій лімфоцитів (Т-клітини, Т-хелпери, Т-цитотоксичні, Т-активовані, T-NK-клітини, В-клітини, NK-клітини) у 43 реципієнтів НАТ залежно від перебігу віддаленого післяопераційного періоду та стану алотрансплантата через 1–9 років після алотрансплантації нирки, які були розподілені згідно з морфологічною верифікацією діагнозу на дві групи. Група 1 — 23 хворі із задовільною функцією НАТ без ознак відторгнення; група 2 — 20 хворих із ХДНА, обумовленою хронічною реакцією відторгнення (ХРВ) за даними пункційної біопсії. До контрольної групи увійшли 23 здорові донори, чиї показники становили референтний коридор. Результати. Дані аналізу показали підвищення середніх рівнів Т-активованих лімфоцитів у групах 1 та 2 щодо контрольної (8,9 ± 2,0; 8,4 ± 2,4; 6,8 ± 2,1 відповідно). Також виявлено зниження середніх показників рівнів T-NK-клітин (2,4 ± 2,0) та В-клітин (9,6 ± 2,0) у групі 2 щодо показників групи 1 (5,6 ± 1,8 та 12,4 ± 2,4 відповідно). Аналіз індексів співвідношення між окремими субпопуляційними одиницями лімфоцитів показав статистично вірогідну значущість різниці між індексом Т-клітини/T-NK-клітини (22,53 vs 46,89 в групах 1 та 2 відповідно; p &lt; 0,05) та індексом Т-активовані/В-клітини (1,14 vs 4,17 в групах 1 та 2 відповідно; p &lt; 0,05). При цьому чутливість індексу Т-клітини/T-NK-клітини становила 70 %, специфічність — 60 %. Чутливість індексу Т-активовані/В-клітини дорівнювала 55 %, специфічність — 50 %. Висновки. Зниження рівня T-NK-клітин ближче до нижнього порогового значення референтного коридора і, відповідно, співвідношення Т-клітини/T-NK-клітини в межах 44,49–49,29 (46,89 ± 2,40) у віддаленому післятрансплантаційному періоді може бути додатковою ознакою ХРВ як причини прогресуючої дисфункції НАТ.

Tertiary lymphoid organs in renal chronic allograft rejection

Abstract Chronic allograft rejection remains a major obstacle to long-term allograft survival. The immunologic role of tertiary lymphoid organs (TLO) in allograft rejection is unclear. Here, we employed a chronic renal allograft rejection model in mice and intravital 2-photon microscopy to investigate the function of TLO in transplant rejection. CB6F1 (F1) RIP-LTα (preformed TLO) or F1 (no TLO) kidney grafts were transplanted to WT B6 recipients and survival monitored. To investigate immunologic function of TLO, we adoptively transferred B6-RIPLTα CD11c-YFP mice with 10m naïve dsRed OT-I T cells or 10m CTR-labeled NP-specific B cells + 10m CFP+ OT-II cells and immunized with NP-OVA + alum. Intravital 2P imaging of renal TLO was performed at time points 0, 3, 6, 24 or 72 hours after immunization. 4D image analysis was performed and mean speed, displacement, arrest coefficient (AC) and contact times (CT) with DC were calculated for OT-I, OT-II and NP-B cells. F1 RIP-LTα grafts rejected significantly faster (MST= 54) than F1 grafts (MST= 225), demonstrating that TLO contribute to allograft rejection. F1 RIP-LTα grafts contained similar numbers of, but larger TLO than F1 grafts as demonstrated by histology. Mean speed and displacement of OT-I and OT-II cells significantly decreased over time after immunization while AC and mean CT significantly increased. B cell mean speed, displacement and AC increased after immunization. These data are consistent with B cell activation and productive T cell-DC interactions and mirror previously reported data in secondary lymphoid organs. We provide first evidence that TLO provide a local structure for T and B cell activation that propagates anti-graft immune responses in the setting of chronic rejection.

The relationship between pathologic lesions of active and chronic antibody-mediated rejection in renal allografts.

The Banff classification of renal allograft pathology defines specific morphologic lesions that are used in the diagnosis of active (glomerulitis, peritubular capillaritis, endarteritis) and chronic (transplant glomerulopathy, peritubular capillary basement membrane multilayering, transplant arteriopathy) antibody-mediated rejection (ABMR). However, none of these individual lesions are specific for ABMR, and for this reason Banff requires 1 or more additional findings, including C4d deposition in peritubular capillaries, presence of circulating donor-specific antibodies (DSAs), and/or expression in the tissue of transcripts strongly associated with ABMR, for a definitive diagnosis of ABMR to be made. In addition, while animal studies examining serial biopsies have established the progression of morphologic lesions of active to chronic ABMR as well as intermediate forms (chronic active ABMR) exhibiting features of both, clear documentation that lesions of chronic ABMR require the earlier presence of corresponding active and intermediate lesions is less well established in human renal allografts. This review examines temporal relationships between key morphologic lesions of active and chronic ABMR in biopsies of human grafts, likely intermediate forms, and findings for and possibly against direct and potentially interruptible progression from active to chronic lesions.

Evolving criteria for the diagnosis of antibody-mediated rejection in renal allografts.

To review changes in the Banff schema for antibody-mediated renal allograft rejection over the past decade, including key revisions agreed upon during and immediately subsequent to the 2017 Banff Conference on Allograft Pathology. The original Banff schema for diagnosis of acute and chronic active antibody-mediated rejection (ABMR) in renal allografts was formulated at the 2001 and 2007 Banff Conferences, and required histologic (primarily microvascular inflammation and transplant glomerulopathy), immunohistologic (C4d in peritubular capillaries), and serologic [circulating donor-specific antibodies (DSA)] evidence for a definitive diagnosis of ABMR. This schema was updated at the 2013 Banff Conference, recognizing C4d-negative ABMR, intimal arteritis as a potential manifestation of ABMR, and revising definitions and thresholds for glomerulitis and transplant glomerulopathy to improve interobserver agreement and correlation with clinical, molecular, and serologic data. Compared with the 2007 criteria, Banff 2013 improved the sensitivity of the classification for diagnosing ABMR and the correlation of ABMR diagnosis with graft outcomes. At the 2017 Banff Conference, new modifications to the classification were discussed and have subsequently been agreed upon, accepting C4d and thoroughly validated molecular classifiers as surrogate markers for DSA. From a consensus reached at the 2017 Banff Conference, updated criteria for diagnosis of active and chronic active ABMR have been developed that recognize C4d and molecular classifiers as surrogate markers for DSA. In addition, specific recommendations for the use of molecular diagnostics in the diagnosis of ABMR were developed.

TREATMENTOFRENAL ALLOGRAFTCHRONIC REJECTION

The work is a literature review, which demonstrates the current strategies of the treatment of chronic renal allograft rejection

Renal allograft rejection, lymphocyte infiltration, and de novo donor-specific antibodies in a novel model of non-adherence to immunosuppressive therapy

BackgroundNon-adherence has been associated with reduced graft survival. The aim of this study was to investigate the immunological mechanisms underlying chronic renal allograft rejection using a model of non-adherence to immunosuppressive therapy. We used a MHC (major histocompatibility complex) -mismatched rat model of renal transplantation (Brown Norway to Lewis), in which rats received daily oral cyclosporine A. In analogy to non-adherence to therapy, one group received cyclosporine A on alternating days only. Rejection was histologically graded according to the Banff classification. We quantified fibrosis by trichrome staining and intra-graft infiltration of T cells, B cells, and monocytes/macrophages by immunohistochemistry. The distribution of B lymphocytes was assessed using immunofluorescence microscopy. Intra-graft chemokine, chemokine receptor, BAFF (B cell activating factor belonging to the TNF family), and immunoglobulin G transcription levels were analysed by RT-PCR. Finally, we evaluated donor-specific antibodies (DSA) and complement-dependent cytotoxicity using flow cytometry.ResultsAfter 28 days, cellular rejection occurred during non-adherence in 5/6 animals, mixed with humoral rejection in 3/6 animals. After non-adherence, the number of T lymphocytes were elevated compared to daily immunosuppression. Monocyte numbers declined over time. Accordingly, lymphocyte chemokine transcription was significantly increased in the graft, as was the transcription of BAFF, BAFF receptor, and Immunoglobulin G. Donor specific antibodies were elevated in non-adherence, but did not induce complement-dependent cytotoxicity.ConclusionCellular and humoral rejection, lymphocyte infiltration, and de novo DSA are induced in this model of non-adherence.

Marrow Mesenchymal Stem Cells Effectively Reduce Histologic Changes in a Rat Model of Chronic Renal Allograft Rejection

BackgroundChronic allograft rejection remains as the leading cause of the chronic renal grafts loss post-transplantation. No therapy has been found really effective to prevent and treat chronic allograft rejection. Mesenchymal stem cells (MSCs) have characteristics of immunomodulation and are expected to be used for inducing graft immune tolerance in organ transplantation. We investigated the efficacy and safety of early infusion of donor-derived marrow MSCs in a rat model of chronic renal allograft rejection. MethodsOrthotopic kidney transplantations were performed in a rat strain combination of Sprague-Dawley (SD) → Wistar. The native right kidneys of recipient rats were kept intact as internal control of each graft. Twenty-three successfully transplanted recipient rats were divided into 3 groups: group 1 (the MSCs therapy group) (n = 8) and group 2 (the control group) (n = 8) both received a 10-day course of cyclosporine (CsA) (2 mg/kg intraperitoneally) to prevent initial acute rejection. MSCs (1 × 107) of first dosage and an additional dosage were injected into group 1 postoperative days (PODs) 0, 3, and 7. Group 2 received 0.9% saline solution in addition to CsA as the control group. Group 3 consisted of recipients (n = 7) receiving neither immunosuppression nor MSCs. Renal histopathology and immunohistochemistry of transforming growth factor β1 (TGF-β1) was examined at week 12. Safety of MSC infusion was determined by observing symptoms and signs after infusion and performing gross anatomy at week 12. ResultsAll the grafts of group 3 developed acute rejection and were rejected within 4 weeks. Bone marrow MSCs significantly decreased the severity of mononuclear cell interstitial inflammation, tubular atrophy, interstitial fibrosis, and vascular fibrous intimal thickening in renal grafts (P < .001). MSCs also greatly reduced the glomerulosclerosis rate of the transplanted kidneys of group 1 (P < .001). The TGF-ß1 expression of group 1 was weaker than that of group 2 (P = .043). There were no symptoms or signs of severe adverse side effects observed. ConclusionsEarly bone marrow MSCs infusion on PODs 0, 3, and 7 are effective and safe for chronic renal allograft rejection in rats. MSCs hold significant promise for clinical transplantation to treat chronic renal allograft rejection and prolong the renal graft survival.

Prevention of chronic renal allograft rejection by AS2553627, a novel JAK inhibitor, in a rat transplantation model

BackgroundJanus kinase (JAK) inhibitors are thought to be promising candidates to aid renal transplantation. However, the effectiveness of JAK inhibitors against features of chronic rejection, including interstitial fibrosis/tubular atrophy (IF/TA) and glomerulosclerosis, has not been elucidated. Here, we investigated the effect of AS2553627, a novel JAK inhibitor, on the development of chronic rejection in rat renal transplantation. MethodsLewis (LEW) to Brown Norway (BN) rat renal transplantation was performed. Tacrolimus (TAC) at 0.1mg/kg was administered intramuscularly once a day for 10 consecutive days starting on the day of transplantation (days 0 to 9) to prevent initial acute rejection. After discontinuation of TAC treatment from days 10 to 28, AS2553627 (1 and 10mg/kg) was orally administered with TAC. At 13weeks after renal transplantation, grafts were harvested for histopathological and mRNA analysis. Creatinine and donor-specific antibodies were measured from plasma samples. Urinary protein and kidney injury markers were also evaluated. ResultsAS2553627 in combination with TAC exhibited low plasma creatinine and a marked decrease in urinary protein and kidney injury markers, such as tissue inhibitor of metalloproteinase-1 and kidney injury molecule-1. At 13weeks, histopathological analysis revealed that AS2553627 treatment inhibited glomerulosclerosis and IF/TA. In addition, upregulation of cell surface markers, fibrosis/epithelial–mesenchymal transition and inflammation-related genes were reduced by the combination of AS2553672 and TAC, particularly CD8 and IL-6 mRNAs, indicating that AS2553627 prevented cell infiltration and inflammation in renal allografts. ConclusionsThese results indicate the therapeutic potential of JAK inhibitors in chronic rejection progression, and suggest that AS2553627 is a promising agent to improve long-term graft survival after renal transplantation.

Chronic Antibody-Mediated Rejection in Nonhuman Primate Renal Allografts: Validation of Human Histological and Molecular Phenotypes.

Molecular testing represents a promising adjunct for the diagnosis of antibody-mediated rejection (AMR). Here, we apply a novel gene expression platform in sequential formalin-fixed paraffin-embedded samples from nonhuman primate (NHP) renal transplants. We analyzed 34 previously described gene transcripts related to AMR in humans in 197 archival NHP samples, including 102 from recipients that developed chronic AMR, 80 from recipients without AMR, and 15 normal native nephrectomies. Three endothelial genes (VWF, DARC, and CAV1), derived from 10-fold cross-validation receiver operating characteristic curve analysis, demonstrated excellent discrimination between AMR and non-AMR samples (area under the curve = 0.92). This three-gene set correlated with classic features of AMR, including glomerulitis, capillaritis, glomerulopathy, C4d deposition, and DSAs (r = 0.39-0.63, p < 0.001). Principal component analysis confirmed the association between three-gene set expression and AMR and highlighted the ambiguity of v lesions and ptc lesions between AMR and T cell-mediated rejection (TCMR). Elevated three-gene set expression corresponded with the development of immunopathological evidence of rejection and often preceded it. Many recipients demonstrated mixed AMR and TCMR, suggesting that this represents the natural pattern of rejection. These data provide NHP animal model validation of recent updates to the Banff classification including the assessment of molecular markers for diagnosing AMR.

Longitudinal evaluation of perfusion changes in acute and chronic renal allograft rejection using arterial spin labeling in translational mouse models.

To examine the longitudinal changes of renal perfusion due to acute and chronic renal allograft rejection by using arterial spin labeling (ASL) MRI in translational mouse models of isogenic and allogenic kidney transplantation (ktx). Acute rejection was induced by allogenic ktx of C57BL/6 (B6)-kidney grafts to BALB/c-recipients with prolonged cold ischemia (CIT) of 60 minutes (n = 13). To induce chronic rejection BALB/c-kidneys were transplanted into B6-recipients with short CIT of 30 minutes (n = 22). Isogenic grafts without rejection (n = 14 with prolonged, n = 9 with short CIT) and normal kidneys (n = 22) were used for comparison. Perfusion was measured on a 7T small-animal magnetic resonance imaging (MRI) scanner using flow-sensitive alternating inversion recovery (FAIR) ASL-sequences at day 1 and 6 (acute) or at week 3 and 6 (chronic) after surgery. Histological analyses of grafts included inflammation, vascular changes, and fibrosis. In the acute ktx model, ASL showed perfusion impairment in isogenic and allogenic kidney grafts. Perfusion of allografts further decreased until day 6 and remained stable in isografts without rejection (allogenic ktx 62 ± 21 vs. isogenic ktx 181 ± 39 ml/min/100g, P < 0.01). In the chronic ktx model, perfusion in isografts was similar to normal kidneys over the entire observation period. Perfusion was severely reduced in allografts compared to isografts (week 3: 28 ± 7 vs. 310 ± 46 ml/min/100g, P < 0.001, week 6: 32 ± 5 vs. 367 ± 72 ml/min/100g, P < 0.001). Histological analysis revealed severe inflammation, vascular occlusion, and rejection in allografts. Chronic rejection grafts showed endothelialitis, peritubular capillaritis, interstitial fibrosis, and tubular atrophy. ASL allows longitudinal assessment of renal perfusion impairment due to acute and chronic renal allograft rejection in translational mouse models. 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1664-1672.

Genomic Analysis of Kidney Allograft Injury Identifies Hematopoietic Cell Kinase as a Key Driver of Renal Fibrosis.

Renal fibrosis is the common pathway of progression for patients with CKD and chronic renal allograft injury (CAI), but the underlying mechanisms remain obscure. We performed a meta-analysis in human kidney biopsy specimens with CAI, incorporating data available publicly and from our Genomics of Chronic Renal Allograft Rejection study. We identified an Src family tyrosine kinase, hematopoietic cell kinase (Hck), as upregulated in allografts in CAI. Querying the Kinase Inhibitor Resource database revealed that dasatinib, a Food and Drug Administration-approved drug, potently binds Hck with high selectivity. In vitro, Hck overexpression activated the TGF-β/Smad3 pathway, whereas HCK knockdown inhibited it. Treatment of tubular cells with dasatinib reduced the expression of Col1a1 Dasatinib also reduced proliferation and α-SMA expression in fibroblasts. In a murine model with unilateral ureteric obstruction, pretreatment with dasatinib significantly reduced the upregulation of profibrotic markers, phosphorylation of Smad3, and renal fibrosis observed in kidneys pretreated with vehicle alone. Dasatinib treatment also improved renal function, reduced albuminuria, and inhibited expression of profibrotic markers in animal models with lupus nephritis and folic acid nephropathy. These data suggest that Hck is a key mediator of renal fibrosis and dasatinib could be developed as an antifibrotic drug.

COMPARISON OF DIFFERENT METHODS OF ANTI-HLA ANTIBODIES DETECTION IN DIAGNOSIS OF ANTIBODY-MEDIATED RENAL ALLOGRAFT REJECTION

Aim: to analyze the relationship between circulating anti-HLA antibodies (class-I and class-II), renal pathology and C4d deposition in cases of late acute and chronic antibody-mediated renal allograft rejection according to the method of antibodies detection (ELISA and LUMINEX). Materials and methods. Th e study included 192 patients with indicative graft biopsies (with C4d-staining) and screening detection of anti-HLA antibodies (109 patients by ELISA, 58 patients by LUMINEX, 25 patients – both methods). Patients were divided into 3 groups based on pathology fi ndings: 85 patients with chronic graft rejection, 39 patients with acute antibodymediated rejection (AMR), 68 patients of control group had no signs of AMR. Results. Anti-HLA antibodies (predominantly class-II anti-HLA) were identifi ed in 84.7% of patients with chronic graft rejection, in 84.6% of patients with acute AMR and 33.8% of control group (р &lt; 0.001). Close correlation between the levels of anti￾HLA antibodies detected by different methods was revealed for both classes of antibodies (r² class-I anti-HLA = 0.773, r² class-II anti-HLA = 0.379, р &lt; 0.01). LUMINEX proved to be more sensitive in anti-HLA antibodies detection in all groups. It was especially signifi cant for the diagnosis of C4d-negative acute AMR whose frequen￾cies were 22.2% and 4.8% in detection by LUMINEX and ELISA, respectively (р &lt; 0.01). On the other hand, anti-HLA antibodies being detected by LUMINEX in 55% of patients of the control group more often required determination of donor specifi city. Conclusion. Screening of anti-HLA antibodies (by ELISA and LUMINEX) along with specifi c renal pathology and C4d deposition is suffi cient for the diagnosis of acute and chronic AMR in most cases. Being more sensitive LUMINEX method is preferable for the revealing of C4d-negative AMR, but it requires specifi c DSA detection in many cases.

Current pathological perspectives on chronic rejection in renal allografts.

Chronic rejection in renal transplantation clinically manifests as slow deterioration in allograft function and is a major contributor of late renal graft loss. Most cases of chronic rejection involve chronic antibody-mediated rejection (ABMR) triggered by the interaction of donor-specific alloantibodies with endothelial cells of the microcirculation. The evolution of the Banff classification involved a major revision of the ABMR criteria during the 2000s and led to the inclusion of detailed pathological characteristics of chronic ABMR in the 2013 Banff scheme, including microcirculation damage observed as newly formed basement membranes and arterial fibrous intimal proliferation. Inflammation of microvasculature including glomeruli and/or peritubular capillaries is also seen in substantial cases of chronic ABMR, defined as chronic active ABMR. Chronic active T cell-mediated rejection (TCMR) results from chronic T cell-mediated injury involving renal arteries but is less characterized under the current Banff classification, mainly due to the expanding histological criteria of chronic active ABMR. Characteristics shared by these two chronic rejection types can potentially cause diagnostic confusion. Hence, the diagnostic criteria or categories of chronic renal rejection require amendment of the current Banff classification. Assessment of rejection cases with molecular phenotyping advanced the mechanistic understanding of various dysfunctions in renal allograft, including ABMR and TCMR. Identification of disease-specific changes in gene expression by immunohistological studies, especially in chronic ABMR, has already been validated by several studies, warranting potential application to the pathological diagnostic process. This review provides an overview of current pathological perspectives on chronic rejection of renal allografts and future directions.