Intrarenal resistive index after renal transplantation.

BACKGROUND: The intrarenal resistive index is routinely measured in many renal-transplantation centers for assessment of renal-allograft status, although the value of the resistive index remains unclear. METHODS: In a single-center, prospective study involving 321 renal-allograft recipients, we measured the resistive index at baseline, at the time of protocol-specified renal-allograft biopsies (3, 12, and 24 months after transplantation), and at the time of biopsies performed because of graft dysfunction. A total of 1124 renal-allograft resistive-index measurements were included in the analysis. All patients were followed for at least 4.5 years after transplantation. RESULTS: Allograft recipients with a resistive index of at least 0.80 had higher mortality than those with a resistive index of less than 0.80 at 3, 12, and 24 months after transplantation (hazard ratio, 5.20 [95% confidence interval {CI}, 2.14 to 12.64; P<0.001]; 3.46 [95% CI, 1.39 to 8.56; P=0.007]; and 4.12 [95% CI, 1.26 to 13.45; P=0.02], respectively). The need for dialysis did not differ significantly between patients with a resistive index of at least 0.80 and those with a resistive index of less than 0.80 at 3, 12, and 24 months after transplantation (hazard ratio, 1.95 [95% CI, 0.39 to 9.82; P=0.42]; 0.44 [95% CI, 0.05 to 3.72; P=0.45]; and 1.34 [95% CI, 0.20 to 8.82; P=0.76], respectively). At protocol-specified biopsy time points, the resistive index was not associated with renal-allograft histologic features. Older recipient age was the strongest determinant of a higher resistive index (P<0.001). At the time of biopsies performed because of graft dysfunction, antibody-mediated rejection or acute tubular necrosis, as compared with normal biopsy results, was associated with a higher resistive index (0.87 ± 0.12 vs. 0.78 ± 0.14 [P=0.05], and 0.86 ± 0.09 vs. 0.78 ± 0.14 [P=0.007], respectively). CONCLUSIONS: The resistive index, routinely measured at predefined time points after transplantation, reflects characteristics of the recipient but not those of the graft. (ClinicalTrials.gov number, NCT01879124 .).

Genomic biomarkers correlate with HLA-identical renal transplant tolerance.

The ability to achieve immunologic tolerance after transplantation is a therapeutic goal. Here, we report interim results from an ongoing trial of tolerance in HLA-identical sibling renal transplantation. The immunosuppressive regimen included alemtuzumab induction, donor hematopoietic stem cells, tacrolimus/mycophenolate immunosuppression converted to sirolimus, and complete drug withdrawal by 24 months post-transplantation. Recipients were considered tolerant if they had normal biopsies and renal function after an additional 12 months without immunosuppression. Of the 20 recipients enrolled, 10 had at least 36 months of follow-up after transplantation. Five of these 10 recipients had immunosuppression successfully withdrawn for 16-36 months (tolerant), 2 had disease recurrence, and 3 had subclinical rejection in protocol biopsies (nontolerant). Microchimerism disappeared after 1 year, and CD4(+)CD25(high)CD127(-)FOXP3(+) regulatory T cells and CD19(+)IgD/M(+)CD27(-) B cells were increased through 5 years post-transplantation in both tolerant and nontolerant recipients. Immune/inflammatory gene expression pathways in the peripheral blood and urine, however, were differentially downregulated between tolerant and nontolerant recipients. In summary, interim results from this trial of tolerance in HLA-identical renal transplantation suggest that predictive genomic biomarkers, but not immunoregulatory phenotyping, may be able to discriminate tolerant from nontolerant patients.

Genomic meta-analysis of growth factor and integrin pathways in chronic kidney transplant injury.

BACKGROUND: Chronic Allograft Nephropathy (CAN) is a clinical entity of progressive kidney transplant injury. The defining histology is tubular atrophy with interstitial fibrosis (IFTA). Using a meta-analysis of microarrays from 84 kidney transplant biopsies, we revealed growth factor and integrin adhesion molecule pathways differentially expressed and correlated with histological progression. A bioinformatics approach mining independent datasets leverages new and existing data to identify correlative changes in integrin and growth factor signaling pathways. RESULTS: Analysis of CAN/IFTA Banff grades showed that hepatocyte growth factor (HGF), and epidermal growth factor (EGF) pathways are significantly differentially expressed in all classes of CAN/IFTA. MAPK-dependent pathways were also significant. However, the TGFß pathways, albeit present, failed to differentiate CAN/IFTA progression. The integrin subunits ß8, αv, αµ and ß5 are differentially expressed, but ß1, ß6 and α6 specifically correlate with progression of chronic injury. Results were validated using our published proteomic profiling of CAN/IFTA. CONCLUSIONS: CAN/IFTA with chronic kidney injury is characterized by expression of distinct growth factors and specific integrin adhesion molecules as well as their canonical signaling pathways. Drug target mapping suggests several novel candidates for the next generation of therapeutics to prevent or treat progressive transplant dysfunction with interstitial fibrosis.

Transvenous Renal Transplant Biopsy via a Transfemoral Approach.

Percutaneous renal biopsy (PRB) of kidney transplants might be prevented by an elevated risk of bleeding or limited access to the allograft. In the following, we describe our initial experience with 71 transvenous renal transplant biopsies in 53 consecutive patients with unexplained reduced graft function who were considered unsuitable candidates for PRB (4.2% of all renal transplant biopsies at our institution). Biopsies were performed via the ipsilateral femoral vein with a renal biopsy set designed for transjugular renal biopsy (TJRB) of native kidneys. Positioning of the biopsy system within the transplant vein was achievable in 58 of 71 (81.7%) procedures. The specimen contained a median of 10 glomeruli (range 0-38). Tissue was considered as adequate for diagnosis in 56 of 57 (98.2%) biopsies. With respect to BANFF 50.9% of the specimen were adequate (>10 glomeruli), 47.4% marginally adequate (1-9 glomeruli) and 1.8% inadequate (no glomeruli). After implementation of real-time assessment all specimen contained glomeruli. One of the fifty-eight (1.8%) procedure-related major complications occurred (hydronephrosis requiring nephrostomy due to gross hematuria). Transfemoral renal transplant biopsy (TFRTB) is feasible and appears to be safe compared to PRB. It offers a useful new alternative for histological evaluation of graft dysfunction in selected patients with contraindications to PRB.

Cryptic B cell response to renal transplantation.

Transplantation reliably evokes allo-specific B cell and T cell responses in mice. Yet, human recipients of kidney transplants with normal function usually exhibit little or no antibody specific for the transplant donor during the early weeks and months after transplantation. Indeed, the absence of antidonor antibodies is taken to reflect effective immunosuppressive therapy and to predict a favorable outcome. Whether the absence of donor-specific antibodies reflects absence of a B cell response to the donor, tolerance to the donor or immunity masked by binding of donor-specific antibodies to the graft is not known. To distinguish between these possibilities, we devised a novel ELISPOT, using cultured donor, recipient and third-party fibroblasts as targets. We enumerated donor-specific antibody-secreting cells in the blood of nine renal allograft recipients with normal kidney function before and after transplantation. Although none of the nine subjects had detectable donor-specific antibodies before or after transplantation, all exhibited increases in the frequency of donor-specific antibody-secreting cells eight weeks after transplantation. The responses were directed against the donor HLA-class I antigens. The increase in frequency of donor-specific antibody-secreting cells after renal transplantation indicates that B cells respond specifically to the transplant donor more often than previously thought.

Combination of IL-1 receptor antagonist, IL-20 and CD40 ligand for the prediction of acute cellular renal allograft rejection.

PURPOSE: The outcome of renal transplantation is difficult to predict, even with an allograft biopsy. The aim of this study was to develop a sensitive, specific and noninvasive method for prediction of acute cellular rejection (ACR). METHODS: Luminex analysis was used to determine the levels of 95 cytokines/chemokines and their soluble receptors in sera from recipients with: ACR (in the first month post-transplantation, before and during rejection, and after rejection reversal); stable allograft function; delayed graft function (DGF); pulmonary infection. Evaluation of significant differential protein expression in ACR patients compared with stable allograft controls revealed a three-analyte combination as a marker of renal transplantation outcome. The predictive value of this combination was further validated in DGF and infection groups and in a blind binary code study of 24 additional serum samples. RESULTS: Significant differential expression was detected in 26 proteins expressed in patients during the period preceding an ACR episode compared with stable controls. A blood test for discrimination of such patients was developed based on the simultaneous quantification of three analytes (IL-1 receptor antagonist, IL-20 and sCD40 ligand). This test exhibited 90.9 % sensitivity, 96 % specificity, a positive predictive value (PPV) of 95.2 % and a negative predictive value (NPV) of 92.3 %. Moreover, this combination allowed discrimination between patients with ACR and DGF and pulmonary infection. CONCLUSIONS: With further development and validation, this blood test can be used to predict ACR and direct the treatment of transplant patients in the clinic.

Kidney transplant: functional assessment with diffusion-tensor MR imaging at 3T.

PURPOSE: To evaluate the feasibility of diffusion-tensor (DT) imaging at 3 T for functional assessment of transplanted kidneys. MATERIALS AND METHODS: This study was approved by the local ethics committee; written informed consent was obtained. Between August 2009 and October 2010, 40 renal transplant recipients were prospectively included in this study and examined with a clinical 3-T magnetic resonance (MR) imager. An echo-planar DT imaging sequence was performed in coronal orientation by using five b values (0, 200, 400, 600, 800 sec/mm(2)) and 20 diffusion directions. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were determined for the cortex and medulla of the transplanted kidney. Relationships between FA, ADC, and allograft function, determined by the estimated glomerular filtration rate (eGFR), were assessed by using Pearson correlation coefficient. ADC and FA were compared between patients with good or moderate allograft function (group A; eGFR > 30 mL/min/1.73 m(2)) and patients with impaired function (group B; eGFR ≤ 30 mL/min/1.73 m(2)) by using a student t test. P < .05 indicated a statistically significant difference. RESULTS: Mean FA of the renal medulla and cortex was significantly higher in group A (0.39 ± 0.06 and 0.17 ± 0.4) compared with group B (0.27 ± 0.05 and 0.14 ± 0.03) (P < .001 and P = .009, respectively). Mean ADCs of renal cortex and medulla were significantly higher in group A than in group B (P = .007 and P = .01, respectively). In group B, mean medullary FA was significantly lower in patients whose renal function did not recover (0.22 ± 0.02) compared with those with stable allograft function at 6 months (0.29 ± 0.05, P < .001). There was significant correlation between eGFR and medullary FA (r = 0.65, P < .001), cortical ADC (r = 0.43, P = .003), and medullary ADC (r = 0.35, P = .01). CONCLUSION: DT imaging is a promising noninvasive technique for functional assessment of renal allografts. FA values in the renal medulla exhibit a good correlation with renal function.

Arteriolar lesions in renal transplant biopsies: prevalence, progression, and clinical significance.

Arteriolar hyalinosis in kidney transplants is considered the histopathologic hallmark of chronic calcineurin inhibitor (CNI) toxicity. However, the lesion is not specific. We assessed prevalence, progression, and clinical significance of arteriolar lesions in 1239 renal transplant sequential protocol biopsy samples and 408 biopsy for cause samples in 526 patients. Associations between arteriolar lesions and presumed risk factors, concomitant histopathologic lesions, demographic factors, and graft function were evaluated. The frequency of arteriolar lesions was stable during the first 2 years after transplantation, and increased thereafter (14.8% at 6 months versus 48.6% at >2 years; P < 0.0001). We were unable to find associations with diabetes, hypertension, or CNI therapy. However, patients with early arteriolar lesions received grafts from older donors (mean ± SD age, 54.4 ± 13.4 years versus 43.1 ± 16.6 years; P < 0.0001), and had inferior graft function (estimated glomerular filtration rate 55 ± 21 mL/min versus 63 ± 24 mL/min at 6 weeks, 53 ± 19 mL/min versus 60 ± 23 mL/min at 1 year, and 49 ± 19 mL/min versus 59 ± 22 mL/min at 2 years; P < 0.05). Evaluation of late biopsy samples from patients not receiving CNI therapy revealed a high prevalence of AH without clear-cut identifiable underlying cause. Reproducibility of arteriolar lesions was at best moderate (κ ≤ 0.62). Sampling error in sequential biopsy samples was frequent. In conclusion, in samples from sequential protocol biopsies and biopsies for cause in individual patients, arteriolar lesions in renal transplants not only increase over time without being specific for CNI toxicity but are affected by sampling error and limited reproducibility.

Sirolimus inhibits lymphangiogenesis in rat renal allografts, a novel mechanism to prevent chronic kidney allograft injury.

Lymphangiogenesis occurs in renal allografts and it may be involved in the maintenance of the alloreactive immune response and thus participate in the development of chronic kidney allograft injury. Sirolimus (SRL) has been shown to inhibit lymphangiogenesis. The aim of this study was to describe lymphangiogenesis and its regulation during the development of chronic kidney allograft injury and to investigate the effect of SRL on allograft lymphangiogenesis and chronic kidney allograft injury. A rat renal transplantation model was used. Allografts treated with cyclosporine A or with SRL were analyzed in various time points. Syngenic transplantations were used as controls. Kidney function was followed with serum creatinine. Histology was analyzed by Chronic Allograft Damage Index (CADI). Immunohistochemistry was used to detect lymphatic vessels, VEGF-C and VEGFR-3. In cyclosporine-treated allografts VEGF-C/VEGFR-3 pathway was strongly upregulated leading to extensive lymphangiogenesis 60 days after transplantation. Lymphangiogenesis correlated positively with the CADI score. Sirolimus efficiently inhibited lymphangiogenesis, improved graft function and attenuated the development of chronic kidney allograft injury when compared with cyclosporine. In conclusion, lymphangiogenesis is associated with chronic kidney allograft injury and SRL is a potent inhibitor of lymphangiogenesis in renal allografts. Inhibition of lymphatic proliferation could mediate the nephroprotective properties of SRL.

Contributions of direct and indirect alloresponses to chronic rejection of kidney allografts in nonhuman primates.

The relative contribution of direct and indirect allorecognition pathways to chronic rejection of allogeneic organ transplants in primates remains unclear. In this study, we evaluated T and B cell alloresponses in cynomolgus monkeys that had received combined kidney/bone marrow allografts and myeloablative immunosuppressive treatments. We measured donor-specific direct and indirect T cell responses and alloantibody production in monkeys (n = 5) that did not reject their transplant acutely but developed chronic humoral rejection (CHR) and in tolerant recipients (n = 4) that never displayed signs of CHR. All CHR recipients exhibited high levels of anti-donor Abs and mounted potent direct T cell alloresponses in vitro. Such direct alloreactivity could be detected for more than 1 y after transplantation. In contrast, only two of five monkeys with CHR had a detectable indirect alloresponse. No indirect alloresponse by T cells and no alloantibody responses were found in any of the tolerant monkeys. Only one of four tolerant monkeys displayed a direct T cell alloresponse. These observations indicate that direct T cell alloresponses can be sustained for prolonged periods posttransplantation and result in alloantibody production and chronic rejection of kidney transplants, even in the absence of detectable indirect alloreactivity.

B lymphocytes differentially influence acute and chronic allograft rejection in mice.

The relative contributions of B lymphocytes and plasma cells during allograft rejection remain unclear. Therefore, the effects of B cell depletion on acute cardiac rejection, chronic renal rejection, and skin graft rejection were compared using CD20 or CD19 mAbs. Both CD20 and CD19 mAbs effectively depleted mature B cells, and CD19 mAb treatment depleted plasmablasts and some plasma cells. B cell depletion did not affect acute cardiac allograft rejection, although CD19 mAb treatment prevented allograft-specific IgG production. Strikingly, CD19 mAb treatment significantly reduced renal allograft rejection and abrogated allograft-specific IgG development, whereas CD20 mAb treatment did not. By contrast, B cell depletion exacerbated skin allograft rejection and augmented the proliferation of adoptively transferred alloantigen-specific CD4(+) T cells, demonstrating that B cells can also negatively regulate allograft rejection. Thereby, B cells can either positively or negatively regulate allograft rejection depending on the nature of the allograft and the intensity of the rejection response. Moreover, CD19 mAb may represent a new approach for depleting both B cells and plasma cells to concomitantly impair T cell activation, inhibit the generation of new allograft-specific Abs, or reduce preexisting allograft-specific Ab levels in transplant patients.

Lymphatic endothelial progenitor cells contribute to de novo lymphangiogenesis in human renal transplants.

De novo lymphangiogenesis influences the course of different human diseases as diverse as chronic renal transplant rejection and tumor metastasis. The cellular mechanisms of lymphangiogenesis in human diseases are currently unknown, and could involve division of local preexisting endothelial cells or incorporation of circulating progenitors. We analyzed renal tissues of individuals with gender-mismatched transplants who had transplant rejection and high rates of overall lymphatic endothelial proliferation as well as massive chronic inflammation. Donor-derived cells were detected by in situ hybridization of the Y chromosome. We compared these tissues with biopsies of essentially normal skin and intestine, and two rare carcinomas with low rates of lymphatic endothelial proliferation that were derived from individuals with gender-mismatched bone marrow transplants. Here, we provide evidence for the participation of recipient-derived lymphatic progenitor cells in renal transplants. In contrast, lymphatic vessels of normal tissues and those around post-transplant carcinomas did not incorporate donor-derived progenitors. This indicates a stepwise mechanism of inflammation-associated de novo lymphangiogenesis, implying that potential lymphatic progenitor cells derive from the circulation, transmigrate through the connective tissue stroma, presumably in the form of macrophages, and finally incorporate into the growing lymphatic vessel.

Renal stem cells: fact or science fiction?

The kidney is widely regarded as an organ without regenerative abilities. However, in recent years this dogma has been challenged on the basis of observations of kidney recovery following acute injury, and the identification of renal populations that demonstrate stem cell characteristics in various species. It is currently speculated that the human kidney can regenerate in some contexts, but the mechanisms of renal regeneration remain poorly understood. Numerous controversies surround the potency, behaviour and origins of the cell types that are proposed to perform kidney regeneration. The present review explores the current understanding of renal stem cells and kidney regeneration events, and examines the future challenges in using these insights to create new clinical treatments for kidney disease.

Cellular senescence limits regenerative capacity and allograft survival.

Long-term graft survival after kidney transplantation remains unsatisfactory and unpredictable. Interstitial fibrosis and tubular atrophy are major contributors to late graft loss; features of tubular cell senescence, such as increased p16(INK4a) expression, associate with these tubulointerstitial changes, but it is unknown whether the relationship is causal. Here, loss of the INK4a locus in mice, which allows escape from p16(INK4a)-dependent senescence, significantly reduced interstitial fibrosis and tubular atrophy and associated with improved renal function, conservation of nephron mass, and transplant survival. Compared with wild-type controls, kidneys from INK4a(-/-) mice developed significantly less interstitial fibrosis and tubular atrophy after ischemia-reperfusion injury. Consistently, mice that received kidney transplants from INK4a/ARF(-/-) donors had significantly better survival 21 days after life-supporting kidney transplantation and developed less tubulointerstitial changes. This correlated with higher proliferative rates of tubular cells and significantly fewer senescent cells. Taken together, these data suggest a pathogenic role of renal cellular senescence in the development of interstitial fibrosis and tubular atrophy and kidney graft deterioration by preventing the recovery from injury. Inhibiting premature senescence could have therapeutic benefit in kidney transplantation but has to be balanced against the risks of suspending antitumor defenses.

Color Doppler ultrasound-guided transducer compression of post biopsy bleeding of kidney transplants.

BACKGROUND: Color Doppler ultrasound (CDUS) has a potential of early detection of post biopsy bleeding. We describe CDUS guidance in planning, acquisition, and, in the case of bleeding, compression of the needle tract in biopsy procedures of kidney transplants. METHODS: Eighty-three kidney transplant biopsy procedures performed on clinical indication were performed in 71 adult patients, 25 women, mean age 51 years, using CDUS and 18-G biopsy needles. Bleeding needle tracts were compressed using CDUS guidance. RESULTS: CDUS immediately detected blood leakage and facilitated compression of the bleeding needle tract in 34 (41%) of the 83 procedures, including 53 (25%) of 215 needle passes. In 34 bleeding procedures, the mean duration of the longest bleeding time after a needle pass was 124 seconds (median, 20 seconds; range, 3-1440 seconds). In 12 of these procedures (35%), the bleeding time was 30 seconds or more. In six procedures (18%), a bleeding of 120 seconds or more was observed. Complications included seven small hematomas. Five hematomas developed in procedures where the longest duration CD bleeding was 120 seconds or more. CONCLUSIONS: CDUS detects bleeding and facilitates direct transducer compression of the needle tract in a substantial portion of biopsy procedures of kidney transplants. Only minor hematomas occurred.

Pathology of C4d-negative antibody-mediated rejection in renal allografts.

PURPOSE OF REVIEW: To summarize current evidence supporting the existence of C4d-negative antibody-mediated rejection (AMR) in renal allografts, its potential to cause chronic graft injury, and whether histopathologic features of C4d-negative AMR differ from those of C4d-positive AMR. RECENT FINDINGS: Recently published molecular, clinicopathologic, and ultrastructural studies provide strong evidence that microvascular injury in the presence of donor-specific alloantibodies (DSA) has the potential to cause interstitial fibrosis/tubular atrophy, transplant glomerulopathy, and graft loss, whether or not peritubular capillary (PTC) C4d is present. Although C4d-positive AMR may represent a more severe form of AMR, recent studies have found that in patients with DSA, microvascular injury (glomerulitis, peritubular capillaritis) is more strongly associated with graft loss than C4d deposition. Our data suggest that C4d-positive and C4d-negative AMR show similar degrees of glomerulitis and peritubular capillaritis, similar frequencies of concurrent cell-mediated rejection, and that both may occur early or late posttransplantation. SUMMARY: In renal allografts, microvascular injury in the presence of DSA but with negative C4d staining in PTC nonetheless is indicative of humorally mediated graft injury that has the potential to cause tubular atrophy/interstitial fibrosis, transplant glomerulopathy, and graft loss. Prompt treatment for AMR may prevent or at least delay subsequent development of transplant glomerulopathy.

Renal allograft pathology in the sensitized patient.

PURPOSE OF REVIEW: Patterns of renal allograft injury associated with alloantibody have been increasingly recognized over the past 2 decades. The use of more sensitive serum testing has brought to light the range of alloantibody-associated changes on biopsy at different time points posttransplant. There is likely to be an increasing number of patients with preformed alloantibody undergoing kidney transplantation, and so alloantibody-associated injury will become more prevalent. RECENT FINDINGS: Acute antibody-mediated rejection (AMR) is a major complication in kidney transplant patients with preformed donor-specific antibody (DSA), particularly in the early posttransplant period. Acute AMR is characterized by acute tissue injury and is likely to be antibody mediated and complement mediated. A recent study showed a decreased risk of acute AMR with terminal complement pathway inhibition. Other studies have shown endothelialitis, a vascular lesion traditionally associated with acute cellular rejection, in AMR. Features of chronic AMR are common and include transplant glomerulopathy, peritubular capillary basement membrane multilamination, and accelerated arteriosclerosis. Although previously a diagnosis of humoral rejection usually required complement factor C4d deposition in the graft, we now recognize chronic features because of DSA even in the absence of C4d deposition. SUMMARY: Acute and chronic AMR are major contributors to renal allograft dysfunction and loss. Recognition of tissue injury patterns associated with alloantibody can lead to treatment strategies in patients with DSA and can aid in interpreting biopsies in patients who are receiving new therapies.

Pathology of recurrent diseases in kidney allografts: membranous nephropathy and focal segmental glomerulosclerosis.

PURPOSE OF REVIEW: Glomerulonephritis is the leading cause of end-stage renal failure in renal transplant recipients. Recurrence of diseases in kidney allograft provides a unique opportunity to study the mechanisms of kidney disorders leading to the underlying native organ failure. There have been new advances in the understanding of the mechanisms of membranous nephropathy and focal segmental glomerulosclerosis (FSGS). RECENT FINDINGS: Recent studies of recurrent membranous nephropathy provide evidence of the presence of circulating recipient factor that targets the donor kidney and put forward the evidence of antiphospholipase A2 receptor antibody pathogenicity in some cases, point to a different pathogenesis of recurrent and de-novo membranous nephropathy, and stress the importance of early morphologic recognition of recurrent membranous nephropathy. New advances in understanding the FSGS include identification of soluble podocyte urokinase receptor as a circulating factor leading to the development and recurrence of FSGS after transplantation, imply that podocyte injury may be a reversible lesion, and suggest a dual role of activated parietal epithelial cells in sclerosing glomerular injury as well as in regeneration and repair. SUMMARY: Several new mechanisms of glomerular injury have been implicated in the development of recurrent kidney diseases. When further confirmed, some of these might result in early diagnosis and development of better therapy of the respective disorders.

Clinical significance of the ratio between FOXP3 positive regulatory T cell and interleukin-17 secreting cell in renal allograft biopsies with acute T-cell-mediated rejection.

The aim of this study is to investigate the clinical significance of the ratio between interleukin-17 (IL-17) secreting cell and FOXP3-positive regulatory T cell (FOXP3(+) Treg) infiltration in renal allograft tissues with acute T-cell-mediated rejection (ATCMR). Fifty-six patients with biopsy-proven ATCMR were included. Infiltration of FOXP3(+) Treg and IL-17-secreting cells was evaluated with immunostaining for FOXP3 or IL-17 on the biopsy specimens, and the patients were divided into the FOXP3 high group (Log FOXP3/IL-17 > 0·45) or the IL-17 high group (Log FOXP3/IL-17 < 0·45). We compared the allograft function, severity of tissue injury, and clinical outcome between the two groups. In the IL-17 high group, allograft function was significantly decreased compared with the FOXP3 high group (P < 0·05). The severity of interstitial and tubular injury in the IL-17 high group was higher than the FOXP3 high group (P < 0·05). The proportions of steroid-resistant rejection, incomplete recovery and recurrent ATCMR were higher in the IL-17 high group than in the FOXP3 high group (all indicators, P < 0·05). The IL-17 high group showed lower 1-year (54% versus 90%, P < 0·05) and 5-year (38% versus 85%, P < 0·05) allograft survival rates compared with the FOXP3 high group. Multivariate analysis revealed that the FOXP3/IL-17 ratio was a significant predictor for allograft outcome. The FOXP3/IL-17 ratio is a useful indicator for representing the severity of tissue injury, allograft dysfunction and for predicting the clinical outcome of ATCMR.

Endothelial injury in transplant glomerulopathy is correlated with transcription factor T-bet expression.

Transplant glomerulopathy is an important cause of late graft loss. Inflammatory lesions including glomerulitis and peritubular capillaritis, suggestive of endothelial injury, are prominent in this condition but the mechanism underlying this inflammation remains unclear. Here we measured the expression of T-bet (a member of the T-box family of transcription factors regulating Th1 lineage commitment) and its relationship with inflammation in 70 patients with transplant glomerulopathy. Within this cohort, 32 patients were diagnosed with transplant glomerulopathy, 23 with interstitial fibrosis/tubular atrophy, and 15 with stable grafts. There was a significant increase in T-bet expression in both glomerular and peritubular capillaries of the transplant glomerulopathy group. This expression was strongly correlated with CD4(+), CD8(+), and CD68(+) cell infiltration within glomerular and peritubular capillaries. The expression of GATA3, a Th2 regulator, was rarely found in the transplant glomerulopathy group. Transplant glomerulopathy was associated with diffuse peritubular capillary dilation without reduced capillary density. Moreover, the degree of capillary dilation was significantly correlated with the number of infiltrating CD68(+) cells. Since endothelial injury is a typical lesion that follows alloantibody reactivity, our results suggest that T-bet is involved in the pathogenesis of this glomerulopathy.