The pathology of chronic allograft dysfunction

Tissue-Resident Macrophages in Solid Organ Transplantation: Harmful or Protective?

Transplanted organs carry donor immune cells into the recipient, the majority of which are tissue-resident macrophages (TRMs). The role they play in guiding the fate of the transplanted organ toward acceptance or rejection remains elusive. TRMs originate from both embryonic and bone marrow-derived precursors. Embryo-derived TRMs retain the embryonic capability to proliferate, so they are able to self-renew and, theoretically, persist for extended periods of time after transplantation. Bone marrow-derived TRMs do not proliferate and must constantly be replenished by adult circulating monocytes. Recent studies have aimed to clarify the different roles and interactions between donor TRMs, recipient monocytes, and monocyte-derived macrophages (MFs) after organ transplantation. This review aims to shed light on how MFs affect the fate of a transplanted organ by differentiating between the role of donor TRMs and that of MFs derived from graft infiltrating monocytes.

JAK Inhibitors in Solid Organ Transplantation

Janus kinase (JAK) inhibitors are a novel group of immunosuppressive drugs approved to treat certain rheumatic and allergic disorders; however, their efficacy in the regulation of alloimmune responses after solid organ transplantation has not yet been elucidated. In the present review, we have summarized the results of in vitro, in vivo, experimental, and clinical trial studies about the efficacy and safety of JAK inhibitors in improving allograft survival in solid organ transplantations, including kidney, heart, lung, and liver transplants. Moreover, reports on administering JAK inhibitors to steroid-resistant patients with graft versus host disease (GvHD) after solid organ transplantation have been reviewed. Overall findings are suggestive of a beneficial role for JAK inhibitors in organ transplantation: for example, they have been shown to improve allograft function, reduce the rate and score of acute rejection, downregulate the expression of proinflammatory cytokines and adhesion molecules, and decrease oxidative stress. However, the adverse effects of these drugs, in particular bone marrow suppression and infection, remain an obstacle.

The Immunohistochemical Expression of the Von Willebrand Factor: A Potential Tool to Predict Kidney Allograft Outcomes

Few reports assessed endothelial activation biomarkers in kidney allograft biopsies using immunohistochemistry. This retrospective cohort study evaluated the association between posttransplant outcomes and the immunohistochemistry expression of Caveolin-1, Von Willebrand Factor (Vwf), and T-Cadherin in for-cause biopsies diagnosed as interstitial fibrosis and tubular atrophy of unknown etiology. Samples with antibody-mediated changes were excluded. The patients were followed for 3 years after the biopsy or until graft loss/death. Seventy-one (71) samples from 66 patients were included. Eighteen (25.4%) patients lost their grafts, mainly due to chronic rejection (33.3%). Caveolin-1 and T-Cadherin were not associated with graft loss. Vwf had good accuracy in predicting graft failure (AUC 0.637, 95% CI 0.486 to 0.788 P=0.101). The presence of more than 10% of Vwf positivity in the microvasculature (Vwf >10%) was associated with reduced death-censored graft survival (58.2% vs. 85.4% P=0.006), and this result was also observed in the subgroup presenting mild interstitial fibrosis (ci=1) (65.7% vs. 88.6% P=0.033). The multivariate analysis showed that Vwf >10% was an independent risk factor for graft loss (HR=2.88, 95% CI 1.03 to 8.02 P=0.043). In conclusion, Vwf might be an additional tool to predict allograft outcomes in kidney transplant recipients with interstitial fibrosis and tubular atrophy of unknown etiology, probably reflecting immune endothelial activation.

MicroRNAs in kidney injury and disease

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by degrading or repressing the translation of their target messenger RNAs. As miRNAs are critical regulators of cellular homeostasis, their dysregulation is a crucial component of cell and organ injury. A substantial body of evidence indicates that miRNAs are involved in the pathophysiology of acute kidney injury (AKI), chronic kidney disease and allograft damage. Different subsets of miRNAs are dysregulated during AKI, chronic kidney disease and allograft rejection, which could reflect differences in the physiopathology of these conditions. miRNAs that have been investigated in AKI include miR-21, which has an anti-apoptotic role, and miR-214 and miR-668, which regulate mitochondrial dynamics. Various miRNAs are downregulated in diabetic kidney disease, including the miR-30 family and miR-146a, which protect against inflammation and fibrosis. Other miRNAs such as miR-193 and miR-92a induce podocyte dedifferentiation in glomerulonephritis. In transplantation, miRNAs have been implicated in allograft rejection and injury. Further work is needed to identify and validate miRNAs as biomarkers of graft function and of kidney disease development and progression. Use of combinations of miRNAs together with other molecular markers could potentially improve diagnostic or predictive power and facilitate clinical translation. In addition, targeting specific miRNAs at different stages of disease could be a promising therapeutic strategy.

Cannabinoid Receptor 1 Inhibition in Chronic Kidney Disease: A New Therapeutic Toolbox

Chronic kidney disease (CKD) concerns millions of individuals worldwide, with few therapeutic strategies available to date. Recent evidence suggests that the endocannabinoid system (ECS) could be a new therapeutic target to prevent CKD. ECS combines receptors, cannabinoid receptor type 1 (CB1R) and type 2 (CB2R), and ligands. The most prominent receptor within the kidney is CB1R, its endogenous local ligands being anandamide and 2-arachidonoylglycerol. Therefore, the present review focuses on the therapeutic potential of CB1R and not CB2R. In the normal kidney, CB1R is expressed in many cell types, especially in the vasculature where it contributes to the regulation of renal hemodynamics. CB1R could also participate to water and sodium balance and to blood pressure regulation but its precise role remains to decipher. CB1R promotes renal fibrosis in both metabolic and non-metabolic nephropathies. In metabolic syndrome, obesity and diabetes, CB1R inhibition not only improves metabolic parameters, but also exerts a direct role in preventing renal fibrosis. In non-metabolic nephropathies, its inhibition reduces the development of renal fibrosis. There is a growing interest of the industry to develop new CB1R antagonists without central nervous side-effects. Experimental data on renal fibrosis are encouraging and some molecules are currently under early-stage clinical phases (phases I and IIa studies). In the present review, we will first describe the role of the endocannabinoid receptors, especially CB1R, in renal physiology. We will next explore the role of endocannabinoid receptors in both metabolic and non-metabolic CKD and renal fibrosis. Finally, we will discuss the therapeutic potential of CB1R inhibition using the new pharmacological approaches. Overall, the new pharmacological blockers of CB1R could provide an additional therapeutic toolbox in the management of CKD and renal fibrosis from both metabolic and non-metabolic origin.

Urinary vitronectin identifies patients with high levels of fibrosis in kidney grafts

BACKGROUND

In kidney transplantation, fibrosis represents the final and irreversible consequence of the pathogenic mechanisms that lead to graft failure, and in the late stages it irremediably precedes the loss of renal function. The invasiveness of kidney biopsy prevents this condition from being frequently monitored, while clinical data are rather unspecific. The objective of this study was to find noninvasive biomarkers of kidney rejection.

METHODS

We carried out proteomic analysis of the urinary Extracellular Vesicles (uEVs) from a cohort of kidney transplant recipients (n = 23) classified according to their biopsy-based diagnosis and clinical parameters as interstitial fibrosis and tubular atrophy (IFTA), acute cellular rejection (ACR), calcineurin inhibitors toxicity (CNIT) and normal kidney function (NKF).

RESULTS

Shotgun mass spectrometry of uEV-proteins identified differential expression of several proteins among these different groups. Up to 23 of these proteins were re-evaluated using targeted proteomics in a new independent cohort of patients (n = 41) classified in the same diagnostic groups. Among other results, we found a differential expression of vitronectin (VTN) in patients displaying chronic interstitial and tubular lesions (ci and ct mean > 2 according to Banff criteria). These results were further confirmed by a pilot study using enzyme-linked immunosorbent assay (ELISA).

CONCLUSION

Urinary vitronectin levels are a potential stand-alone biomarker to monitor fibrotic changes in kidney transplant recipients in a non-invasive fashion.

Usefulness of morphometric image analysis with Sirius Red to assess interstitial fibrosis after renal transplantation from uncontrolled circulatory death donors

Early interstitial fibrosis (IF) correlates with long-term renal graft dysfunction, highlighting the need for accurate quantification of IF. However, the currently used Banff classification exhibits some limitations. The aim of our study was to precisely describe the progression of IF after renal transplantation using a new morphometric image analysis method relying of Sirius Red staining. The morphometric analysis we developed showed high inter-observer and intra-observer reproducibility, with ICC [95% IC] of respectively 0.75 [0.67–0.81] (n = 151) and 0.88 [0.72–0.95] (n = 21). We used this method to assess IF (mIF) during the first year after the kidney transplantation from 66 uncontrolled donors after circulatory death (uDCD). Both mIF and interstitial fibrosis (ci) according to the Banff classification significantly increased the first three months after transplantation. From M3 to M12, mIF significantly increased whereas Banff classification failed to highlight increase of ci. Moreover, mIF at M12 (p = 0.005) correlated with mean time to graft function recovery and was significantly associated with increase of creatininemia at M12 and at last follow-up. To conclude, the new morphometric image analysis method we developed, using a routine and cheap staining, may provide valuable tool to assess IF and thus to evaluate new sources of grafts.

Urinary MicroRNA-21-5p as Potential Biomarker of Interstitial Fibrosis and Tubular Atrophy (IFTA) in Kidney Transplant Recipients

Chronic renal allograft dysfunction (CAD) is a major limiting factor of long-term graft survival. The hallmarks of progressive CAD are interstitial fibrosis and tubular atrophy (IFTA). MicroRNAs are small, regulatory RNAs involved in many immunological processes. In particular, microRNA-21-5p (miR-21) is considered to be strongly associated with pathogenesis regarding tubulointerstitium. The aim of this study was to assess urinary miR-21 expression levels in the kidney transplant recipients and determine their application in the evaluation of IFTA and kidney allograft function. The expression levels of miR-21 were quantified in the urine of 31 kidney transplant recipients with biopsy-assessed IFTA (IFTA 0 + I: n = 17; IFTA II + III: n = 14) by real-time quantitative PCR. Urine samples were collected at the time of protocolar biopsies performed 1 or 2 years after kidney transplantation. MicroRNA-191-5p was used as reference gene. MiR-21 was significantly up-regulated in IFTA II + III group compared to IFTA 0 + I group (p = 0.003). MiR-21 correlated significantly with serum concentration of creatinine (r = 0.52, p = 0.003) and eGFR (r = -0.45; p = 0.01). ROC analysis determined the diagnostic value of miR-21 with an area under curve (AUC) of 0.80 (p = 0.0002), sensitivity of 0.86 and specificity of 0.71. miR-21 is associated with renal allograft dysfunction and IFTA. Therefore, it could be considered as a potential diagnostic, non-invasive biomarker for monitoring renal graft function.

Nanodelivery of Mycophenolate Mofetil to the Organ Improves Transplant Vasculopathy

Inflammation occurring within the transplanted organ from the time of harvest is an important stimulus of early alloimmune reactivity and promotes chronic allograft rejection. Chronic immune-mediated injury remains the primary obstacle to the long-term success of organ transplantation. However, organ transplantation represents a rare clinical setting in which the organ is accessible ex vivo, providing an opportunity to use nanotechnology to deliver therapeutics directly to the graft. This approach facilitates the directed delivery of immunosuppressive agents (ISA) to target local pathogenic immune responses prior to the transplantation. Here, we have developed a system of direct delivery and sustained release of mycophenolate mofetil (MMF) to treat the donor organ prior to transplantation. Perfusion of a donor mouse heart with MMF-loaded PEG-PLGA nanoparticles (MMF-NPs) prior to transplantation abrogated cardiac transplant vasculopathy by suppressing intragraft pro-inflammatory cytokines and chemokines. Our findings demonstrate that ex vivo delivery of an ISA to donor organs using a nanocarrier can serve as a clinically feasible approach to reduce transplant immunity.

Progenitor-derived human endothelial cells evade alloimmunity by CRISPR/Cas9-mediated complete ablation of MHC expression

Tissue engineering may address organ shortages currently limiting clinical transplantation. Off-the-shelf engineered vascularized organs will likely use allogeneic endothelial cells (ECs) to construct microvessels required for graft perfusion. Vasculogenic ECs can be differentiated from committed progenitors (human endothelial colony-forming cells or HECFCs) without risk of mutation or teratoma formation associated with reprogrammed stem cells. Like other ECs, these cells can express both class I and class II major histocompatibility complex (MHC) molecules, bind donor-specific antibody (DSA), activate alloreactive T effector memory cells, and initiate rejection in the absence of donor leukocytes. CRISPR/Cas9-mediated dual ablation of β2-microglobulin and class II transactivator (CIITA) in HECFC-derived ECs eliminates both class I and II MHC expression while retaining EC functions and vasculogenic potential. Importantly, dually ablated ECs no longer bind human DSA or activate allogeneic CD4+ effector memory T cells and are resistant to killing by CD8+ alloreactive cytotoxic T lymphocytes in vitro and in vivo. Despite absent class I MHC molecules, these ECs do not activate or elicit cytotoxic activity from allogeneic natural killer cells. These data suggest that HECFC-derived ECs lacking MHC molecule expression can be utilized for engineering vascularized grafts that evade allorejection.

The cannabinoid receptor 1 is involved in renal fibrosis during chronic allograft dysfunction: Proof of concept

Chronic allograft dysfunction (CAD), defined as the replacement of functional renal tissue by extracellular matrix proteins, remains the first cause of graft loss. The aim of our study was to explore the potential role of the cannabinoid receptor 1 (CB1) during CAD. We retrospectively quantified CB1 expression and correlated it with renal fibrosis in 26 kidney‐transplanted patients who underwent serial routine kidney biopsies. Whereas CB1 expression was low in normal kidney grafts, it was highly expressed during CAD, especially in tubular cells. CB1 expression significantly increased early on after transplantation, from day 0 (D0) to month 3 post‐transplant (M3) (22.5% ± 15.4% vs 33.4% ± 13.8%, P < .01), and it remained stable thereafter. CB1 expression correlated with renal fibrosis at M3 (P = .04). In an in vitro model of tacrolimus‐mediated fibrogenesis by tubular cells, we found that tacrolimus treatment significantly induced mRNA and protein expression of CB1 concomitantly to col3a1 and col4a3 up regulation. Administration of rimonabant, a CB1 antagonist, blunted collagen synthesis by tubular cells (P < .05). Overall, our study strongly suggests an involvement of the cannabinoid system in the progression of fibrosis during CAD and indicates the therapeutic potential of CB1 antagonists in this pathology.

Comparison of ultrasound shear wave elastography with magnetic resonance elastography and renal microvascular flow in the assessment of chronic renal allograft dysfunction

Background Monitoring of renal allograft function is essential for early identification of dysfunction and improvement of kidney transplant (KTX) outcome. Purpose To non-invasively assess renal stiffness in KTX recipients using ultrasound shear wave elastography (USE) in correlation with multifrequency magnetic resonance elastography (MRE), renal allograft function, and renal microvascular flow determined using a novel ultrasound microvascular imaging technique. Material and Methods This prospective study investigated 25 KTXs (functional KTX [FCT], n = 14; chronic KTX insufficiency [DYS], n = 11) in 20 KTX recipients (mean age = 43 ± 14 years). USE was performed using a high-frequency broadband linear transducer and compared with MRE. Shear wave velocity (SWV) was correlated with the estimated glomerular filtration rate (eGFR). Qualitative differences in renal microvascular flow were obtained using SMI. Results FCT had higher SWV than DYS in both cortex and pyramids (cortex, FCT: 3.75 ± 0.82 m/s vs. DYS: 2.79 ± 0.73 m/s, P = 0.0002; pyramid, FCT: 2.89 ± 0.46 m/s vs. DYS: 2.39 ± 0.34 m/s, P = 0.044). Cutoff values of 3.265 m/s for cortex, 2.535 m/s for pyramids, and 2.985 m/s for combined non-hilar parenchyma provided sensitivities of 72.7%, 77.8%, and 90.9% and specificities of 71.4%, 78.6%, and 85.7% for detecting renal allograft dysfunction with area under the receiver operating characteristic curve (AUC) values of 0.831, 0.841, 0.925 (95% confidence interval [CI] = 0.67-0.99, 0.66-1.02, 0.83-1.03). USE correlated positively with eGFR ( r = 0.741, P = 0.0004) and with MRE-derived SWV ( r = 0.562, P = 0.004). Renal microvascular flow was decreased in DYS. Conclusion USE is sensitive to renal allograft dysfunction, which is characterized by reduced SWV and renal perfusion. USE has higher image resolution than MRE, while MRE has slightly better diagnostic accuracy.

Decreased expression of sirtuin 3 protein correlates with early stage chronic renal allograft dysfunction in a rat kidney model

Chronic renal allograft dysfunction (CRAD) is the primary factor affecting the long-term survival of patients who have undergone renal transplantation. Oxidative stress and inflammation serve an important role in the pathological damage caused by CRAD in the early post-transplantation phase. Previous studies have demonstrated that sirtuin 3 (sirt3) protects cells from oxidative stress and inflammation. A model of renal orthotopic transplantation was established in the current study and kidney samples were harvested from the rats 12 weeks following surgery. Compared with the control groups, there were significantly increased levels of serum creatinine, blood urea nitrogen and 24 h urinary protein in the allograft group (P<0.05). Pathological examinations indicated mononuclear cell infiltration and intimal proliferation in the allograft group, which had a higher Banff score compared with the control groups. There were increased levels of malondialdehyde, decreased sirt3 protein expression and decreased superoxide dismutase enzyme activity in the allograft group compared with the control groups (P<0.05). In addition, there was a negative correlation between the expression of sirt3 and 24 h urinary protein excretion, serum creatinine levels, tubulointerstitial mononuclear cell infiltration, smooth muscle cell migration in the vascular wall and Banff scores. Thus, sirt3 may serve an important protective role in the early stage of CRAD.

Tissue Expression of Aquaporin 2 Is Correlated to Urine Output and Allograft Function in Sensitized Kidney Transplant Patients

BACKGROUND

Salt and water disturbances often occur during acute kidney allograft dysfunction that contribute to graft failure, but this condition has been poorly investigated in the alloreactivity setting. We evaluated the tissue expression of aquaporins (AQP1 and AQP2) and the epithelial sodium channel (ENAC) in kidney biopsy specimens from sensitized kidney transplant recipients.

METHODS

Eighty-six biopsy specimens from 33 sensitized patients were divided into 3 groups according to clinical context: time-zero (n = 9), protocol (n = 9), and indication (n = 68). The indication biopsy specimens were further divided into 3 subgroups according to the presence of acute tubular necrosis or rejection. Normal kidney tissue samples (n = 6) served as the control specimens. Immmunohistochemical expression of AQP1, AQP2, and ENAC was determined by using image analyzing software.

RESULTS

Significantly lower AQP1 expression was observed in the time-zero and indication biopsy specimens with rejection compared with control specimens (P = .03 and P = .04, respectively). AQP2 expression was significantly lower in patients with an indication biopsy specimen compared with control and protocol biopsy specimens (P = .05 and P = .005). For ENAC, a lower expression was noted in the indication biopsy specimens compared with the control specimens (P = .04). Both AQP1 and AQP2 tissue expressions were significantly correlated to urine output (r = 0.45 and r = 0.32; P = .001 and P = .02), and AQP2 was correlated with the glomerular filtration rate estimated by using the Modification of Diet in Renal Disease Study equation at biopsy (r = 0.23; P = .05).

CONCLUSIONS

These findings partially confirm previous experimental data showing downregulation of AQP1 expression after ischemia/reperfusion injury and during rejection. AQP2 downregulation seems to be rejection-independent, occurring during deteriorating or poor kidney graft function.

Macrophage-to-Myofibroblast Transition Contributes to Interstitial Fibrosis in Chronic Renal Allograft Injury

Interstitial fibrosis is an important contributor to graft loss in chronic renal allograft injury. Inflammatory macrophages are associated with fibrosis in renal allografts, but how these cells contribute to this damaging response is not clearly understood. Here, we investigated the role of macrophage-to-myofibroblast transition in interstitial fibrosis in human and experimental chronic renal allograft injury. In biopsy specimens from patients with active chronic allograft rejection, we identified cells undergoing macrophage-to-myofibroblast transition by the coexpression of macrophage (CD68) and myofibroblast (α-smooth muscle actin [α-SMA]) markers. CD68⁺/α-SMA⁺ cells accounted for approximately 50% of the myofibroblast population, and the number of these cells correlated with allograft function and the severity of interstitial fibrosis. Similarly, in C57BL/6J mice with a BALB/c renal allograft, cells coexpressing macrophage markers (CD68 or F4/80) and α-SMA composed a significant population in the interstitium of allografts undergoing chronic rejection. Fate-mapping in Lyz2-Cre/Rosa26-Tomato mice showed that approximately half of α-SMA⁺ myofibroblasts in renal allografts originated from recipient bone marrow-derived macrophages. Knockout of Smad3 protected against interstitial fibrosis in renal allografts and substantially reduced the number of macrophage-to-myofibroblast transition cells. Furthermore, the majority of macrophage-to-myofibroblast transition cells in human and experimental renal allograft rejection coexpressed the M2-type macrophage marker CD206, and this expression was considerably reduced in Smad3-knockout recipients. In conclusion, our studies indicate that macrophage-to-myofibroblast transition contributes to interstitial fibrosis in chronic renal allograft injury. Moreover, the transition of bone marrow-derived M2-type macrophages to myofibroblasts in the renal allograft is regulated via a Smad3-dependent mechanism.

Molecular Profile of Mitochondrial Dysfunction in Kidney Transplant Biopsies Is Associated With Poor Allograft Outcome

BACKGROUND

In kidney transplantation (KT), progression of chronic histological damage with subclinical inflammation is associated with poor long-term allograft survival. The role of nonimmunological pathways in chronic allograft injury has not been fully assessed.

METHODS

We analyzed a public microarray dataset that used 1-year protocol kidney transplant biopsy specimens to investigate whether nonimmunological genes and pathways might influence long-term allograft outcome. The selected microarray dataset included 3 patient/sample groups based on their histological findings: normal histology (n = 25), interstitial fibrosis alone (IF alone, n = 24), and interstitial fibrosis with inflammation (IF+i, n = 16). The IF+i group had lower death-censored graft survival and renal function in patients with a mean follow-up of 4 years. We performed statistical analysis comparing gene expression patterns in the 3 group samples.

RESULTS

Gene cluster enrichment and group-specific expression patterns demonstrated a divergent pattern between mitochondrial and immune response genes, with downregulation of mitochondrial genes in the IF+i group. Gene ontological analysis of the downregulated mitochondrial genes identified generation of precursor metabolite and energy, and response to oxidative stress as the most significant biological processes. The transcription regulation pathway analysis of downregulated gene cluster demonstrated transcription factors involved in mitochondrial biogenesis.

CONCLUSIONS

The molecular signature of mitochondrial dysfunction reflects mitochondrial energetic insufficiency, and inadequate antioxidant response involved in mitochondria biogenesis pathways is associated with IF+i and worse long-term allograft survival. Thus, mitochondria function impairment appears to be an important nonimmune factor involved in chronic allograft injury.

Early withdrawal of calcineurin inhibitor from a sirolimus-based immunosuppression stabilizes fibrosis and the transforming growth factor-β signalling pathway in kidney transplant

AIM

The focus in renal transplantation is to increase long-term allograft survival. One of the limiting factors is calcineurin inhibitor (CNI)-induced fibrosis. This study attempted to examine the histological aspect of interstitial fibrosis and the modulation of the transforming growth factor-β (TGF-β) canonical signalling pathway following early withdrawal of CNI from sirolimus-based immunosuppressive therapy.

METHODS

Forty-five kidney transplant recipients with low-medium immunologic risk were randomized and underwent protocol biopsies obtained at the time of transplantation and at 3 and 12 months thereafter. The recipients were taking tacrolimus, sirolimus and prednisone. After the 3rd month, patients were randomized into two groups: sirolimus (SRL) (removed CNI and increased sirolimus) and tacrolimus (TAC) (maintained CNI). Renal biopsies were analyzed according to Banff's 2007 criteria. The sum of Banff's ct and ci constituted the chronicity index. Fibrosis was evaluated by the histomorphometrical analysis of the total collagen and myofibroblast deposition. Immunohistochemical characterization and quantification of TGF-β, TGF-β receptor 1 (TGF-β-R1), receptor 2 (TGF-β-R2) and phospho-Smad2/3 (p-Smad2/3) were performed.

RESULTS

Maintenance of CNI was associated with the increase of the surface density of collagen and α-smooth muscle actin (α-SMA), (P = 0.001). Furthermore, increased TGF-β (P = 0.02), TGF-β-R1 (P = 0.02), p-Smad2/3 (P = 0.03) and stabilized TGF-β-R2. On the other hand, the removal of CNI with increase in the dose of sirolimus limited the enhancement of the chronicity index at 12 m (SRL, 2.18 vs TAC, 3.12, P = 0.0007), diminished the deposition of fibrosis and promoted the stabilization of TGF-β, TGF-β-R2, p-Smad2/3 and myofibroblasts as well as the reduction of TGF-β-R1 (P = 0.01).

CONCLUSION

The early withdrawal of CNI limited the fibrosis progression through the stabilization of chronicity index and of the canonical TGF-β signalling pathway.

siRNA technology in kidney transplantation: current status and future potential

Kidney transplantation is one of the most common transplantation operations in the world, accounting for up to 50 % of all transplantation surgeries. To curtail the damage to transplanted organs that is caused by ischemia-reperfusion injury and the recipient's immune system, small interfering RNA (siRNA) technology is being explored. Importantly, the kidney as a whole is a preferential site for non-specific systemic delivery of siRNA. To date, most attempts at siRNA-based therapy for transplantation-related conditions have remained at the in vitro stage, with only a few of them being advanced into animal models. Hydrodynamic intravenous injection of naked or carrier-bound siRNAs is currently the most common route for delivery of therapeutic constructs. To our knowledge, no systematic screens for siRNA targets most relevant for kidney transplantation have been attempted so far. A majority of researchers have arrived at one or another target of interest by analyzing current literature that dissects pathological processes taking place in transplanted organs. A majority of the genes that make up the list of 53 siRNA targets that have been tested in transplantation-related models so far belong to either apoptosis- or immune rejection-centered networks. There is an opportunity for therapeutic siRNA combinations that may be delivered within the same delivery vector or injected at the same time and, by targeting more than one pathway, or by hitting the same pathways within two different key points, will augment the effects of each other.

Personalization of the immunosuppressive treatment in renal transplant recipients: the great challenge in "omics" medicine

Renal transplantation represents the most favorable treatment for patients with advanced renal failure and it is followed, in most cases, by a significant enhancement in patients’ quality of life. Significant improvements in one-year renal allograft and patients’ survival rates have been achieved over the last 10 years primarily as a result of newer immunosuppressive regimens. Despite these notable achievements in the short-term outcome, long-term graft function and survival rates remain less than optimal. Death with a functioning graft and chronic allograft dysfunction result in an annual rate of 3%–5%. In this context, drug toxicity and long-term chronic adverse effects of immunosuppressive medications have a pivotal role. Unfortunately, at the moment, except for the evaluation of trough drug levels, no clinically useful tools are available to correctly manage immunosuppressive therapy. The proper use of these drugs could potentiate therapeutic effects minimizing adverse drug reactions. For this purpose, in the future, “omics” techniques could represent powerful tools that may be employed in clinical practice to routinely aid the personalization of drug treatment according to each patient’s genetic makeup. However, it is unquestionable that additional studies and technological advances are needed to standardize and simplify these methodologies.

Intronic locus determines SHROOM3 expression and potentiates renal allograft fibrosis

Fibrosis underlies the loss of renal function in patients with chronic kidney disease (CKD) and in kidney transplant recipients with chronic allograft nephropathy (CAN). Here, we studied the effect of an intronic SNP in SHROOM3, which has previously been linked to CKD, on the development of CAN in a prospective cohort of renal allograft recipients. The presence of the rs17319721 allele at the SHROOM3 locus in the donor correlated with increased SHROOM3 expression in the allograft. In vitro, we determined that the sequence containing the risk allele at rs17319721 is a transcription factor 7-like 2-dependent (TCF7L2-dependent) enhancer element that functions to increase SHROOM3 transcription. In renal tubular cells, TGF-β1 administration upregulated SHROOM3 expression in a β-catenin/TCF7L2-mediated manner, while SHROOM3 in turn facilitated canonical TGF-β1 signaling and increased α1 collagen (COL1A1) expression. Inducible and tubular cell-specific knockdown of Shroom3 markedly abrogated interstitial fibrosis in mice with unilateral ureteric obstruction. Moreover, SHROOM3 expression in allografts at 3 months after transplant and the presence of the SHROOM3 risk allele in the donor correlated with increased allograft fibrosis and with reduced estimated glomerular filtration rate at 12 months after transplant. Our findings suggest that rs17319721 functions as a cis-acting expression quantitative trait locus of SHROOM3 that facilitates TGF-β1 signaling and contributes to allograft injury.

Bortezomib in late antibody-mediated kidney transplant rejection (BORTEJECT Study): study protocol for a randomized controlled trial

Background

Despite major advances in transplant medicine, improvements in long-term kidney allograft survival have not been commensurate with those observed shortly after transplantation. The formation of donor-specific antibodies (DSA) and ongoing antibody-mediated rejection (AMR) processes may critically contribute to late graft loss. However, appropriate treatment for late AMR has not yet been defined. There is accumulating evidence that the proteasome inhibitor bortezomib may substantially affect the function and integrity of alloantibody-secreting plasma cells. The impact of this agent on the course of late AMR has not so far been systematically investigated.

Methods/design

The BORTEJECT Study is a randomized controlled trial designed to clarify the impact of intravenous bortezomib on the course of late AMR. In this single-center study (nephrological outpatient service, Medical University Vienna) we plan an initial cross-sectional DSA screening of 1,000 kidney transplant recipients (functioning graft at ≥180 days; estimated glomerular filtration rate (eGFR) >20 ml/minute/1.73 m²). DSA-positive recipients will be subjected to kidney allograft biopsy to detect morphological features consistent with AMR. Forty-four patients with biopsy-proven AMR will then be included in a double-blind placebo-controlled intervention trial (1:1 randomization stratified for eGFR and the presence of T-cell-mediated rejection). Patients in the active group will receive two cycles of bortezomib (4 × 1.3 mg/m² over 2 weeks; 3-month interval between cycles). The primary end point will be the course of eGFR over 24 months (intention-to-treat analysis). The sample size was calculated according to the assumption of a 5 ml/minute/1.73 m² difference in eGFR slope (per year) between the two groups (alpha: 0.05; power: 0.8). Secondary endpoints will be DSA levels, protein excretion, measured glomerular filtration rate, transplant and patient survival, and the development of acute and chronic morphological lesions in 24-month protocol biopsies.

Discussion

The impact of anti-humoral treatment on the course of late AMR has not yet been systematically investigated. Based on the hypothesis that proteasome inhibition improves the outcome of DSA-positive late AMR, we suggest that our trial has the potential to provide solid evidence towards the treatment of this type of rejection.

Trial registration

Clinicaltrials.gov: NCT01873157.

Increased plasma tissue inhibitors of metalloproteinase concentrations as negative predictors associated with deterioration of kidney allograft function upon long-term observation

Chronic allograft injury (CAI) is the most frequent cause of progressive kidney allograft impairment and eventual loss, which is due to interstitial fibrosis and tubular atrophy (IF/TA). Mechanisms of CAI are not fully understood. Chemokines, cytokines, metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) play roles in fibrosis development. The aims of this study were to evaluate plasma and urine TIMPs (TIMP-1 and TIMP-2), MMPs (MMP-2 and MMP-9), proinflammatory interleukin-6 (IL-6), chemokine (C-C motif) ligand 2 (CCL2 chemokines previously known as monocyte chemoattractant protein-1 [MCP-1]) among 150 recipients beyond 1 year post-renal transplantations and to explore the usefulness of these potential biomarkers of ongoing allograft injury. Renal transplant recipients compared with healthy volunteers (control group) showed significantly increased plasma and urine IL-6, MMP-9, TIMP-1, and TIMP-2, as well as lower plasma MMP-2 and urine CCL2 concentrations. Compared with recipients showing good function those with impairments displayed higher plasma TIMP-1 (P < .001) and TIMP-2 (P = .003) concentrations. The recipient estimated glomerular filtration rate (eGFR) values negatively correlated with plasma TIMP-1 and TIMP-2 levels (r = -0.43; P < .0001 and rs = -0.42; P < .0001, respectively) and with urine IL-6 excretion (rs = -0.33; P < .0001). Multivariate and receiver operating characteristic (ROC) analyses showed TIMP-1 plasma level assessments to be useful estimates of allograft injury.

Emerging roles of autophagy in the stressed kidney allograft

The transplanted kidney integrates a considerable number of tissular stress that challenge cell viability and promote inflammation and fibrogenesis. These injuries ultimately may lead to structural deterioration (ie, interstitial fibrosis and tubular atrophy) and to loss of function. In response to ischemic, toxic, or immunologic insults, which are the most frequent injuries encountered by transplanted kidneys, cells must adapt to maintain vital metabolic functions and to avoid death. Among the adaptive responses activated, autophagy has emerged as an important integrator of various extracellular and intracellular triggers (often related to nutrient availability or immunologic stimuli), which may in turn regulate cell viability and both innate and adaptive immune functions. This review provides an overview of the recent literature on the implications of autophagy in the field of kidney transplantation and discusses future directions for research.

Alloantibody and complement promote T cell-mediated cardiac allograft vasculopathy through noncanonical nuclear factor-κB signaling in endothelial cells

BACKGROUND

Cardiac allograft vasculopathy is the major cause of late allograft loss after heart transplantation. Cardiac allograft vasculopathy lesions contain alloreactive T cells that secrete interferon-γ, a vasculopathic cytokine, and occur more frequently in patients with donor-specific antibody. Pathological interactions between these immune effectors, representing cellular and humoral immunity, respectively, remain largely unexplored.

METHODS AND RESULTS

We used human panel reactive antibody to form membrane attack complexes on allogeneic endothelial cells in vitro and in vivo. Rather than inducing cytolysis, membrane attack complexes upregulated inflammatory genes, enhancing the capacity of endothelial cells to recruit and activate allogeneic interferon-γ--producing CD4(+) T cells in a manner dependent on the activation of noncanonical nuclear factor-κB signaling. Noncanonical nuclear factor-κB signaling was detected in situ within endothelial cells both in renal biopsies from transplantation patients with chronic antibody-mediated rejection and in panel-reactive antibody--treated human coronary artery xenografts in immunodeficient mice. On retransplantation into immunodeficient hosts engrafted with human T cells, panel-reactive antibody--treated grafts recruited more interferon-γ--producing T cells and enhanced cardiac allograft vasculopathy lesion formation.

CONCLUSIONS

Alloantibody and complement deposition on graft endothelial cells activates noncanonical nuclear factor-κB signaling, initiating a proinflammatory gene program that enhances alloreactive T cell activation and development of cardiac allograft vasculopathy. Noncanonical nuclear factor-κB signaling in endothelial cells, observed in human allograft specimens and implicated in lesion pathogenesis, may represent a target for new pharmacotherapies to halt the progression of cardiac allograft vasculopathy.

Comprehensive investigation of the caveolin 2 gene: resequencing and association for kidney transplant outcomes

Caveolae are plasma membrane structures formed from a complex of the proteins caveolin-1 and caveolin-2. Caveolae interact with pro-inflammatory cytokines and are dysregulated in fibrotic disease. Although caveolae are present infrequently in healthy kidneys, they are abundant during kidney injury. An association has been identified between a CAV1 gene variant and long term kidney transplant survival. Chronic, gradual decline in transplant function is a persistent problem in kidney transplantation. The aetiology of this is diverse but fibrosis within the transplanted organ is the common end point. This study is the first to investigate the association of CAV2 gene variants with kidney transplant outcomes. Genomic DNA from donors and recipients of 575 kidney transplants performed in Belfast was investigated for common variation in CAV2 using a tag SNP approach. The CAV2 SNP rs13221869 was nominally significant for kidney transplant failure. Validation was sought in an independent group of kidney transplant donors and recipients from Dublin, Ireland using a second genotyping technology. Due to the unexpected absence of rs13221869 from this cohort, the CAV2 gene was resequenced. One novel SNP and a novel insertion/deletion in CAV2 were identified; rs13221869 is located in a repetitive region and was not a true variant in resequenced populations. CAV2 is a plausible candidate gene for association with kidney transplant outcomes given its proximity to CAV1 and its role in attenuating fibrosis. This study does not support an association between CAV2 variation and kidney transplant survival. Further analysis of CAV2 should be undertaken with an awareness of the sequence complexities and genetic variants highlighted by this study.

Reduction of chronic rejection of renal allografts by anti-transforming growth factor-β antibody therapy in a rat model

There is no effective treatment for chronic rejection (CR) that largely limits long-term survival of kidney transplants. Transforming growth factor (TGF)-β is a fibrogenic factor for tissue fibrosis. This study was to test the efficacy of an anti-TGF-β antibody in preventing the CR of renal allografts in a preclinical model. Male Lewis rats (RT1¹) were orthotopically transplanted with donor kidneys from male Fischer 344 (RT11v1) rats and were treated with either anti-TGF-β or a control antibody. The CR of renal allografts was assessed by semiquantitative histological analyses, and intragraft cytokines and fibrosis-related genes ware examined by PCR arrays. Compared with the control antibody, anti-TGF-β antibody treatment significantly reduced recipients' proteinuria (P = 0.0002), and CR in renal transplants, which was indicated by the fewer injured renal tubules, glomeruli, and interlobular arterioles or arteries, and by less mononuclear cell infiltration and interstitial fibrosis in the anti-TGF-β antibody-treated group (P < 0.05), but not significantly attenuate the ratios of different infiltrating leukocytes. These pathological changes were associated with downregulation of TGF-β1, TGF-β2, and proinflammatory cytokines, or with upregulation of anti-fibrotic HGF, BMP5, and BMP7. The therapeutic effect of the anti-TGF-β antibody was further confirmed by its prevention of graft dysfunction, indicated by lower levels of serum creatinine and blood urea nitrogen or higher creatinine clearance in anti-TGF-β antibody-treated recipients compared with those in control recipients (P < 0.05). In conclusion, the anti-TGF-β antibody (1D11) treatment significantly reduces CR of renal allografts in rats, suggesting the therapeutic potential of this antibody therapy for treating CR of kidney transplants in patients.

Urinary neutrophil gelatinase-associated lipocalin accurately detects acute allograft rejection among other causes of acute kidney injury in renal allograft recipients

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (NGAL) has emerged an early marker protein, predicative of acute kidney injury (AKI) in various clinical settings. Here, we demonstrate urinary NGAL to allow for differential diagnosis of AKI, accurately discriminating acute allograft rejection from other causes of AKI in renal allograft recipients.

METHODS

Urinary NGAL was assessed in spot urine of 182 outpatient renal allograft recipients on maintenance immunosuppression. Samples were blinded and NGAL concentrations determined by enzyme-linked immunosorbent assay. Patient data were classed according to standard criteria into stable allograft function or AKI, and according to underlying pathology into acute allograft rejection or AKI of other cause.

RESULTS

Of the 182 patients investigated, 44 (24.2%) presented with AKI and 9 (4.9%) were diagnosed with acute allograft rejection. In 138 patients with stable allograft function, median urinary NGAL concentration was 7.8 ng/mL (interquartile range, 3.7-17.4 ng/mL). In acute allograft rejection, urinary NGAL concentration was 339 ng/mL (165-499 ng/mL), and in AKI of other cause was 59.1 ng/mL (33.1-136 ng/mL). With a cut-off at 100 ng/mL, urinary NGAL accurately predicted acute rejection as underlying pathology of AKI in our cohort (area under the curve-receiver operating characteristic 0.98, sensitivity 1.0, specificity 0.93). This concept was confirmed in an independent clinical setting in allograft recipients referred to our hospital with AKI.

CONCLUSIONS

Urinary NGAL, at respective cut-off, accurately discriminates acute allograft rejection from other causes of AKI in follow-up after kidney transplantation. As a readily available parameter, urinary NGAL may guide differential diagnosis and initial therapy in allograft recipients with AKI.

Kidney transplants with progressing chronic diseases express high levels of acute kidney injury transcripts

We previously reported that kidney transplants with early acute injury express transcripts indicating injury repair--the acute kidney injury signal. This study investigated the significance of this signal in transplants with other conditions, including rejection and recurrent disease. The injury signal was elevated in biopsies in many different conditions, including T cell-mediated rejection and potentially progressive diseases such as antibody-mediated rejection and glomerulonephritis. A high injury signal correlated with poor function and with inflammation in areas of fibrosis, but not with fibrosis without inflammation. In multivariate survival analysis, the injury signal in late kidney transplant biopsies strongly predicted future graft loss, similar to a published molecular risk score derived in late kidneys. Indeed, the injury signal shared many individual transcripts with the risk score, e.g. ITGB6, VCAN, NNMT. The injury signal was a better predictor of future graft loss than fibrosis, inflammation or expression of collagen genes. Thus the acute injury signal, first defined in early reversible injury, is present in many diseases as a reflection of parenchymal distress, where its significance is dictated by the inducing insult, i.e. treatable/self-limited versus untreatable and sustained. Progression in troubled transplants is primarily a function of ongoing parenchymal injury by disease, not fibrogenesis.

Increased circulating miR-21 levels are associated with kidney fibrosis

MicroRNAs (miRNAs) are a class of noncoding RNA acting at a post-transcriptional level to control the expression of large sets of target mRNAs. While there is evidence that miRNAs deregulation plays a causative role in various complex disorders, their role in fibrotic kidney diseases is largely unexplored. Here, we found a strong up-regulation of miR-21 in the kidneys of mice with unilateral ureteral obstruction and also in the kidneys of patients with severe kidney fibrosis. In addition, mouse primary fibroblasts derived from fibrotic kidneys exhibited higher miR-21 expression level compared to those derived from normal kidneys. Expression of miR-21 in normal primary kidney fibroblasts was induced upon TGFβ exposure, a key growth factor involved in fibrogenesis. Finally, ectopic expression of miR-21 in primary kidney fibroblasts was sufficient to promote myofibroblast differentiation. As circulating miRNAs have been suggested as promising non-invasive biomarkers, we further assess whether circulating miR-21 levels are associated with renal fibrosis using sera from 42 renal transplant recipients, categorized according to their renal fibrosis severity, evaluated on allograft biopsies (Interstitial Fibrosis/Tubular Atrophy (IF/TA). Circulating miR-21 levels are significantly increased in patients with severe IF/TA grade (IF/TA grade 3: 3.0±1.0 vs lower grade of fibrosis: 1.5±1.2; p = 0.001). By contrast, circulating miR-21 levels were not correlated with other renal histological lesions. In a multivariate linear regression model including IF/TA grade and estimated GFR, independent associations were found between circulating miR-21 levels and IF/TA score (ß = 0.307, p = 0.03), and between miR-21 levels and aMDRD (ß = −0.398, p = 0.006). Altogether, these data suggest miR-21 has a key pathogenic role in kidney fibrosis and may represent a novel, predictive and reliable blood marker of kidney fibrosis.

MicroRNA-21 promotes fibrosis of the kidney by silencing metabolic pathways

Scarring of the kidney is a major public health concern, directly promoting loss of kidney function. To understand the role of microRNA (miRNA) in the progression of kidney scarring in response to injury, we investigated changes in miRNA expression in two kidney fibrosis models and identified 24 commonly up-regulated miRNAs. Among them, miR-21 was highly elevated in both animal models and in human transplanted kidneys with nephropathy. Deletion of miR-21 in mice resulted in no overt abnormality. However, miR-21(-/-) mice suffered far less interstitial fibrosis in response to kidney injury, a phenotype duplicated in wild-type mice treated with anti-miR-21 oligonucleotides. Global derepression of miR-21 target mRNAs was readily detectable in miR-21(-/-) kidneys after injury. Analysis of gene expression profiles up-regulated in the absence of miR-21 identified groups of genes involved in metabolic pathways, including the lipid metabolism pathway regulated by peroxisome proliferator-activated receptor-α (Pparα), a direct miR-21 target. Overexpression of Pparα prevented ureteral obstruction-induced injury and fibrosis. Pparα deficiency abrogated the antifibrotic effect of anti-miR-21 oligonucleotides. miR-21 also regulated the redox metabolic pathway. The mitochondrial inhibitor of reactive oxygen species generation Mpv17l was repressed by miR-21, correlating closely with enhanced oxidative kidney damage. These studies demonstrate that miR-21 contributes to fibrogenesis and epithelial injury in the kidney in two mouse models and is a candidate target for antifibrotic therapies.

Challenges and considerations in diagnosing the kidney disease in deteriorating graft function

Despite significant reductions in acute-rejection rates with the introduction of calcineurin inhibitor (CNI)-based immunosuppressive therapy, improvements in long-term graft survival in renal transplantation have been mixed. Improving long-term graft survival continues to present a major challenge in the management of kidney-transplant patients. CNIs are a key component of immunosuppressive therapy, and chronic CNI toxicity has been widely thought to be a major factor in late graft failure. However, recent studies examining the causes of late graft failure in detail have challenged this view, highlighting the importance of antibody-mediated rejection and other factors. In addition, the diagnosis of CNI nephrotoxicity represents a challenge to clinicians, with the potential for over-diagnosis and an inappropriate reduction in immunosuppressive therapy. When graft function is deteriorating, accurately determining the cause of the kidney disease is essential for effective long-term management of the patient. Diagnosis requires a thorough clinical investigation, and in the majority of cases a specific cause can be identified.

Heme oxygenase, inflammation, and fibrosis: the good, the bad, and the ugly?

Upon injury, prolonged inflammation and oxidative stress may cause pathological wound healing and fibrosis, leading to formation of excessive scar tissue. Fibrogenesis can occur in most organs and tissues and may ultimately lead to organ dysfunction and failure. The underlying mechanisms of pathological wound healing still remain unclear, and are considered to be multifactorial, but so far, no efficient anti-fibrotic therapies exist. Extra- and intracellular levels of free heme may be increased in a variety of pathological conditions due to release from hemoproteins. Free heme possesses pro-inflammatory and oxidative properties, and may act as a danger signal. Effects of free heme may be counteracted by heme-binding proteins or by heme degradation. Heme is degraded by heme oxygenase (HO) that exists as two isoforms: inducible HO-1 and constitutively expressed HO-2. HO generates the effector molecules biliverdin/bilirubin, carbon monoxide, and free iron/ferritin. HO deficiency in mouse and man leads to exaggerated inflammation following mild insults, and accumulating epidemiological and preclinical studies support the widely recognized notion of the cytoprotective, anti-oxidative, and anti-inflammatory effects of the activity of the HO system and its effector molecules. In this review, we address the potential effects of targeted HO-1 induction or administration of HO-effector molecules as therapeutic targets in fibrotic conditions to counteract inflammatory and oxidative insults. This is exemplified by various clinically relevant conditions, such as hypertrophic scarring, chronic inflammatory liver disease, chronic pancreatitis, and chronic graft rejection in transplantation.

The unfolded protein response regulates an angiogenic response by the kidney epithelium during ischemic stress

Ischemic injuries permanently affect kidney tissue and challenge cell viability, promoting inflammation and fibrogenesis. Ischemia results in nutrient deprivation, which triggers endoplasmic reticulum stress, ultimately resulting in the unfolded protein response (UPR). The aim of this study was to test whether the UPR could promote an angiogenic response independently of the HIF-1α pathway during ischemic stress in the human kidney epithelium. Glucose deprivation induced the secretion of vascular endothelial growth factor A (VEGFA), basic fibroblast growth factor (bFGF) and angiogenin (ANG) in human kidney epithelial cells independently of HIF-1α. Glucose deprivation, but not hypoxia, triggered endoplasmic reticulum stress and activated the UPR. RNA interference-mediated inhibition of the gene encoding the kinase PERK decreased VEGFA and bFGF expression, but neither gene was affected by the inhibition of IRE1α or ATF6. Furthermore, we show that the expression of angiogenin, which inhibits protein synthesis, is regulated by both IRE1α and PERK, which could constitute a complementary function of the UPR in the repression of translation. In a rat model of acute ischemic stress, we show that the UPR is activated in parallel with VEGFA, bFGF, and ANG expression and independently of HIF-1α.

Genetic polymorphisms located in TGFB1, AGTR1, and VEGFA genes are associated to chronic renal allograft dysfunction

BACKGROUND

Persistent inflammation and fibrosis have been related to active progression of renal deterioration and reduced survival of kidney transplant. The aim of this study was to determine the impact of single-nucleotide polymorphisms (SNPs) located in regions related to inflammatory and immune processes on the development of chronic renal allograft dysfunction (CRAD).

METHODS

A retrospective study was carried out on 276 patients who received kidney transplant (KT). SNPs were genotyped via the SNPlex platform. Statistical analysis was performed with SNPstat and regression logistic analyses were adjusted by age and gender of recipients and donors, cold ischemia time and the number of human leukocyte antigen (HLA) mismatches.

RESULTS

From 276 patients with KT, 118 were non-CRAD and 158 were CRAD. Three SNPs showed significant associations with CRAD development: rs1800471 in transforming growth factor beta 1 (TGFB1), rs5186 in angiotensin II receptor type 1 (AGTR1), and rs699947 in vascular endothelial growth factor A (VEGFA). GC genotype of rs1800471 was associated with increased odds of CRAD compared to GG genotype (OR=2.65 (95% confidence interval (CI)=1.09; 6.47), p=0.025), as well as AC and AA genotype of rs699947 assuming a dominant model (OR=1.80 (95% CI=1.02; 3.20), p=0.044). Besides, AC and CC genotypes of rs5186 were associated with reduced odds of CRAD assuming a dominant model (OR=0.56 (95% CI=0.33; 0.96), p=0.033).

CONCLUSION

Our findings suggest that three genes related to immunity and inflammation (rs1800471, rs5186 and rs699947) are associated to susceptibility or protection to CRAD, and might have diagnostic utility in predicting the likelihood of developing CRAD.

Intragraft cytomegalovirus protein expression is associated with reduced renal allograft survival

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for acute and chronic rejection of transplanted organs and is thought to mediate rejection indirectly.

METHODS

In this retrospective observational cohort study, early- and end-stage biopsies from renal allografts lost because of chronic allograft dysfunction (n = 29) were examined for CMV antigens and DNA using immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction.

RESULTS

CMV immediate-early and late proteins were present in 27 (93%) of 29 of the end-stage chronic allograft dysfunction biopsies and in 64% of the corresponding early biopsies but not in pretransplant biopsies from CMV-seronegative donors (n = 3). Graft survival time was reduced in patients with moderate or high CMV levels in the graft soon after transplantation compared with that in patients with no or low CMV levels in the graft. No significant difference was observed in serum creatinine obtained at the time of early biopsies.

CONCLUSIONS

We provide evidence that intragraft CMV protein expression is associated with end-stage chronic renal allograft dysfunction, that intragraft CMV levels increase as graft function deteriorates, and that CMV protein expression in the grafts soon after transplant is associated with reduced graft survival. Thus, CMV may have a pathological role in chronic renal allograft dysfunction.

Induction antibody therapy in renal transplantation using early steroid withdrawal: long-term results comparing anti-IL2 receptor and anti-thymocyte globulin

BACKGROUND

The present study intends to investigate the effects of anti-IL2 receptors (anti-IL2R) vs. lymphocyte-depleting agents in the early steroid withdrawal (ESW) scheme.

METHODS

This is a retrospective cohort of 167 consecutive adult renal transplant recipients. Immunosuppression was based on tacrolimus and mycophenolate mofetil. Antibody induction therapy was carried out with lymphocyte-depleting agent (thymoglobulin) or anti-IL2R (Basiliximab or Daclizumab). ESW protocol was performed by administering intravenous methlyprednisolone as follows: 500 mg on day 0, 250 mg on day 1, 125 mg on day 2, 60 mg on day 3, and then stopped.

RESULTS

Among the 167 studied patients, 79 (47.3%) received anti-IL2R and 88 (52.7%) received thymoglobulin induction. Significantly fewer episodes of acute rejection were seen at one year in patients treated with thymoglobulin as compared to anti-IL2R (25.6% vs. 11.4%, p=0.01). At five years, a significant difference in graft survival was observed in anti-IL2R-treated patients compared with thymoglobulin (83.5% vs. 95.5%, p=0.01). Multivariate analysis disclosed that female sex, antibody induction therapy using thymoglobulin and a trough tacrolimus level higher than 10 were protective factors against acute rejection, while there was a trend to increased risk of acute rejection at first year post-transplantation in patients presenting delayed graft function (DGF). Antibody induction was independently associated with patient and graft survival at five years (OR 0.213, 95% CI 0.046-0.991, p=0.04).

CONCLUSION

ESW scheme seems to be safe and its use is beneficial since there are fewer adverse effects. Thymoglobulin induction therapy is associated with fewer rejection episodes. Induction therapy with thymoglobulin is associated with higher patient and allograft survival when comparing with anti-IL2R.