Renal Graft Fibrosis and Inflammation Quantification by an Automated Fourier-Transform Infrared Imaging Technique

Renal interstitial fibrosis and interstitial active inflammation are the main histologic features of renal allograft biopsy specimens. Fibrosis is currently assessed by semiquantitative subjective analysis, and color image analysis has been developed to improve the reliability and repeatability of this evaluation. However, these techniques fail to distinguish fibrosis from constitutive collagen or active inflammation. We developed an automatic, reproducible Fourier-transform infrared (FTIR) imaging-based technique for simultaneous quantification of fibrosis and inflammation in renal allograft biopsy specimens. We generated and validated a classification model using 49 renal biopsy specimens and subsequently tested the robustness of this classification algorithm on 166 renal grafts. Finally, we explored the clinical relevance of fibrosis quantification using FTIR imaging by comparing results with renal function at 3 months after transplantation (M3) and the variation of renal function between M3 and M12. We showed excellent robustness for fibrosis and inflammation classification, with >90% of renal biopsy specimens adequately classified by FTIR imaging. Finally, fibrosis quantification by FTIR imaging correlated with renal function at M3, and the variation in fibrosis between M3 and M12 correlated well with the variation in renal function over the same period. This study shows that FTIR-based analysis of renal graft biopsy specimens is a reproducible and reliable label-free technique for quantifying fibrosis and active inflammation. This technique seems to be more relevant than digital image analysis and promising for both research studies and routine clinical practice.

Bronchiectasis diagnosed after renal transplantation: a retrospective multicenter study

Background

Bronchiectasis is characterized by abnormal, permanent and irreversible dilatation of the bronchi, usually responsible for daily symptoms and frequent respiratory complications. Many causes have been identified, but only limited data are available concerning the association between bronchiectasis and renal transplantation.

Methods

We conducted a retrospective multicenter study of cases of bronchiectasis diagnosed after renal transplantation in 14 renal transplantation departments (French SPIESSER group). Demographic, clinical, laboratory and CT scan data were collected.

Results

Forty-six patients were included (mean age 58.2 years, 52.2 % men). Autosomal dominant polycystic kidney disease (32.6 %) was the main underlying renal disease. Chronic cough and sputum (50.0 %) were the major symptoms leading to chest CT scan. Mean duration of symptoms before diagnosis was 1.5 years [0–12.1 years]. Microorganisms were identified in 22 patients, predominantly Haemophilus influenzae. Hypogammaglobulinemia was observed in 46.9 % patients. Bronchiectasis was usually extensive (84.8 %). The total bronchiectasis score was 7.4 ± 5.5 with a significant gradient from apex to bases. Many patients remained symptomatic (43.5 %) and/or presented recurrent respiratory tract infections (37.0 %) during follow-up. Six deaths (13 %) occurred during follow-up, but none were attributable to bronchiectasis.

Conclusions

These results highlight that the diagnosis of bronchiectasis should be considered in patients with de novo respiratory symptoms after renal transplantation. Further studies are needed to more clearly understand the mechanisms underlying bronchiectasis in this setting.

[Pathophysiology, epidemiology, clinical presentation, diagnosis and treatment options for autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease (ADPKD) is the leading genetic cause of end-stage renal disease (ESRD) worldwide. Its prevalence is evaluated according to studies and population between 1/1000 and 1/4000 live births and it accounts for 6 to 8% of incident ESRD patients in developed countries. ADPKD is characterized by numerous cysts in both kidneys and various extrarenal manifestations that are detailed in this review. Clinico-radiological and genetic diagnosis are also discussed. Mutations in the PKD1 and PKD2 codifying for polycystin-1 (PC-1) and polycystin-2 (PC-2) are responsible for the 85 and 15% of ADPKD cases, respectively. In primary cilia of normal kidney epithelial cells, PC-1 and PC-2 interact forming a complex involved in flow- and cilia-dependant signalling pathways where intracellular calcium and cAMP play a central role. Alteration of these multiple signal transduction pathways leads to cystogenesis accompanied by dysregulated planar cell polarity, excessive cell proliferation and fluid secretion, and pathogenic interactions of epithelial cells with an abnormal extracellular matrix. The mass effect of expanding cyst is responsible for the decline in glomerular filtration rate that occurs late in the course of the disease. For many decades, the treatment for ADPKD aims to lessen the condition's symptoms, limit kidney damage, and prevent complications. Recently, the development of promising specific treatment raises the hope to slow the growth of cysts and delay the disease. Treatment strategies targeting cAMP signalling such as vasopressin receptor antagonists or somatostatin analogs have been tested successfully in clinical trials with relative safety. Newer treatments supported by preclinical trials will become available in the next future. Recognizing early markers of renal progression (clinical, imaging, and genetic markers) to identify high-risk patients and multidrug approaches with synergistic effects may provide new opportunities for the treatment of ADPKD.

Recurrent IgA nephropathy is predicted by altered glycosylated IgA, autoantibodies and soluble CD89 complexes

IgA nephropathy (IgAN), the most common primary glomerulonephritis worldwide, frequently leads to end-stage renal disease and kidney transplantation. However, disease recurrence often occurs after transplantation. Here we evaluated the predictive value of three markers for IgAN recurrence: the presence of galactose-deficient IgA1, IgG anti-IgA autoantibodies, and IgA-soluble (s) CD89 complexes. This was analyzed in 38 kidney transplant recipients with IgAN recurrence and compared with 22 patients transplanted for IgAN but without recurrence and with 17 healthy controls. Pre-transplantation galactose-deficient IgA1 serum levels were significantly higher in the recurrence compared with the no recurrence or control groups. IgA-IgG complexes were significantly elevated in the recurrence group. Both the recurrence and no recurrence groups had increased values of IgA-sCD89 complexes compared with healthy controls, but values were significantly lower in patients with recurrence compared with no recurrence. Areas under the receiver operating curve of the markers in pre-transplantation sera were 0.86 for galactose-deficient-IgA, 0.82 for IgA-IgG, and 0.78 for sCD89-IgA; all significant. Disease recurrence was associated with decreased serum galactose-deficient IgA1 and appearance of mesangial-galactose-deficient IgA1 deposits, whereas increased serum IgA-sCD89 complexes were associated with mesangial sCD89 deposits. Thus, galactose-deficient-IgA1, IgG autoantibodies, and IgA-sCD89 complexes are valuable biomarkers to predict disease recurrence, highlighting major pathogenic mechanisms in IgAN.

ATG-induced accelerated immune senescence: clinical implications in renal transplant recipients

Persistent ATG-induced CD4(+) T cell lymphopenia is associated with serious clinical complications. We tested the hypothesis that ATG induces accelerated immune senescence in renal transplant recipients (RTR). Immune senescence biomarkers were analyzed at transplant and one-year later in 97 incident RTR -62 patients receiving ATG and 35 receiving anti-CD25 mAb (α-CD25). This consisted in: (i) thymic output; (ii) bone marrow renewal of CD34(+) hematopoietic progenitor cells (CD34(+) HPC) and lymphoid (l-HPC) and myeloid (m-HPC) progenitor ratio; (iii) T cell phenotype; and (iv) measurement of T cell relative telomere length (RTL) and telomerase activity (RTA). Clinical correlates were analyzed with a 3 year follow-up. Thymic output significantly decreased one-year posttransplant in ATG-treated patients. ATG was associated with a significant decrease in l-HPC/m-HPC ratio. Late stage differentiated CD57(+) /CD28(-) T cells increased in ATG-treated patients. One-year posttransplant T cell RTL and RTA were consequently lower in ATG-treated patients. ATG is associated with accelerated immune senescence. Increased frequency of late differentiated CD4(+) T cell frequency at transplantation tended to be predictive of a higher risk of subsequent opportunistic infections and of acute rejection only in ATG-treated patients but this needs confirmation. Considering pretransplant immune profile may help to select those patients who may benefit from ATG to prevent severe infections and acute rejection.

Deletion of receptor for advanced glycation end products exacerbates lymphoproliferative syndrome and lupus nephritis in B6-MRL Fas lpr/j mice

The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor that interacts with advanced glycation end products, but also with C3a, CpG DNA oligonucleotides, and alarmin molecules such as HMGB1 to initiate a proinflammatory reaction. Systemic lupus erythematosus is an autoimmune disorder associated with the accumulation of RAGE ligands. We generated mice invalidated for RAGE in the lupus-prone B6-MRL Fas lpr/j background to determine the role of RAGE in the pathogenesis of systemic lupus erythematosus. We compared the phenotype of these mice with that of their wild-type and B6-MRL Fas lpr/j littermates. Lymphoproliferative syndrome, production of anti-dsDNA Abs, lupus nephritis, and accumulation of CD3(+)B220(+)CD4(-)CD8(-) autoreactive T cells (in the peripheral blood and the spleen) were significantly increased in B6-MRL Fas lpr/j RAGE(-/-) mice compared with B6-MRL Fas lpr/j mice (respectively p < 0.005, p < 0.05, p < 0.001, and p < 0.001). A large proportion of autoreactive T cells from B6-MRL Fas lpr/j mice expressed RAGE at their surface. Time course studies of annexin V expression revealed that autoreactive T cells in the spleen of B6-MRL Fas lpr/j-RAGE(-/-) mice exhibited a delay in apoptosis and expressed significantly less activated caspase 3 (39.5 ± 4.3%) than T cells in B6-MRL Fas lpr/j mice (65.5 ± 5.2%) or wild-type mice (75.3 ± 2.64%) (p = 0.02). We conclude that the deletion of RAGE in B6-MRL Fas lpr/j mice promotes the accumulation of autoreactive CD3(+)B220(+)CD4(-)CD8(-) T cells, therefore exacerbating lymphoproliferative syndrome, autoimmunity, and organ injury. This suggests that RAGE rescues the apoptosis of T lymphocytes when the death receptor Fas/CD95 is dysfunctional.

Contribution of Raman spectroscopy in nephrology: a candidate technique to detect hydroxyethyl starch of third generation in osmotic renal lesions

Raman spectroscopy, a candidate tool for detection of HES, a volume expander administrated after hemodynamic instability, in the kidney.

Germline Mutations in RASA1 Are Not Found in Patients with Klippel-Trenaunay Syndrome or Capillary Malformation with Limb Overgrowth

The RASA1 gene encodes p120RASGAP, a multidomain cytoplasmic protein that acts as a negative regulator of the RAS signalling pathway. Heterozygous loss-of-function RASA1 mutations were identified in patients with Parkes Weber syndrome and multifocal capillary malformations. This syndrome is characterised by a capillary blush on an extremity, arteriovenous microfistulas, and bony and soft tissue hypertrophy. The aim of this study was to test RASA1 in 2 disorders characterised by asymmetric limb enlargement and vascular malformations, namely Klippel-Trenaunay syndrome and regional capillary malformation with overgrowth. We did not identify any clear pathogenic change in these patients. Thus, besides clinical and radiological criteria, RASA1 testing constitutes an additional tool to differentiate Parkes Weber syndrome of capillary malformation-arteriovenous malformation (CM-AVM) from overlapping disorders.

Echocardiography to predict adverse cardiac and vascular events in patients with severe chronic kidney disease (stage 4): a prospective study

BACKGROUND

Cardiovascular disease is the primary cause of mortality and morbidity among patients with chronic kidney disease.

AIMS

To investigate whether echocardiography can predict the occurrence of major cardiovascular events in patients with severe chronic kidney disease.

PATIENTS

Patients with stable stage 4 chronic kidney disease (estimated glomerular filtration rate 15-29 mL/min/1.73 m(2)) and followed in the nephrology department were included. Clinical, biological, electrocardiographic and echocardiographic data were recorded. Endpoint was defined as fatal or non-fatal cardiovascular event (acute coronary syndrome, acute heart failure, stroke, sustained ventricular arrhythmias, arterial thrombotic events and death).

RESULTS

We included 71 patients (46 men); mean age 72±14 years. Mean glomerular filtration rate was 21.9±4.8 mL/min/1.73 m(2). Over a mean follow-up of 258±30 days, 18 (25%) patients reached endpoint (death in 7/18). Male sex, blood urea, atrial fibrillation, Sokolow index, left atrial size, pulmonary arterial pressure, indexed left ventricular mass and protodiastolic peak velocity of transmitral Doppler flow were significantly higher whereas left ventricular ejection fraction was significantly lower in these patients. By multivariable analysis, blood urea and left ventricular ejection fraction remained predictive of major cardiovascular event with odds ratios of 1.10 (95% confidence interval 1.02-1.18) and 0.93 (95% confidence interval 0.89-0.97), respectively. The negative predictive value was 95% when left ventricular ejection fraction was>50% with blood urea<15 mmol/L.

CONCLUSION

Patients with stage 4 chronic kidney disease are at high risk of major cardiovascular events and death. Echocardiographic evaluation is effective in identifying patients at highest risk of adverse cardiac events.

[Time course of digital pressure during dialysis sessions in chronic hemodialysis patients. Prospective observational study of 49 patients]

OBJECTIVES

To describe and compare the evolution of digital pressure on both hands during a dialysis session in patients without digital ischemia, and to identify the parameters influencing the digital pressure.

MATERIALS

Patients with an upper limb vascular access were prospectively included. Digital systolic pressure on the third finger of both hands measured by photoplethysmography and brachial systolic pressure were recorded before dialysis (H0) and every hour (from H1 to H4).

RESULTS

Among 53 patients, 49 were included (exclusions: one surgery for ischemia, one hand tremor, two no consent). None of them had digital ischemia. Digital pressure homolateral to the vascular access was significantly lower compared with controlateral side before and during dialysis. Digital pressure significantly decreased on both sides during dialysis. Brachial pressure decreased significantly compared to H0. Only the brachial pressure decrease was correlated with the decrease of digital pressure. The digital pressure was less than 30 mmHg in six patients. No evidence of digital ischemia was reported after a 6-month follow-up.

CONCLUSION

To our knowledge, this is the first study showing a significant decrease of digital pressure in both hands during hemodialysis in patients without digital ischemia. Further studies are necessary to investigate which parameters can affect digital pressure and to look for clinical consequence of this measurement.

Comparison of C4d detection on erythrocytes and PTC-C4d to histological signs of antibody-mediated rejection in kidney transplantation

C4d on erythrocytes (EC4d), C4d peritubular capillary deposition (PTC-C4d) staining and histology were compared in a cross-sectional cohort of 146 renal allograft biopsies (132 patients). EC4d levels paralleled PTC-C4d staining, but were more predictive of peritubular capillaritis (PTC). Donor-specific antibodies (DSA), PTC-C4d, EC4d and PTC were analyzed in an independent longitudinal follow-up cohort (96 biopsies, 76 patients). Seventy-six samples were PTC and EC4d concordant, 11 positive and 65 negative, 7 PTC-EC4d+ and 13 PTC+EC4d-. EC4d levels were related to DSA occurrence. With ABMR defined by PTC and DSA, all apparently discordant patients, EC4d negative, were correctly reassigned comparing EC4d level curves with rejection kinetics, with positive EC4d samples predating biopsy or late biopsies compared with ABMR flare-ups. All EC4d-positive patients without PTC or DSA had permanent high EC4d levels unrelated to rejection. EC4d was more abundant in PTC-positive (mean = 108.5%± 3.4; n = 50) than PTC-negative samples (mean = 88.1%± 1.3; n= 96; p < 0.0001). Sensitivity, specificity, positive predictive value and negative predictive value of PTC-C4d and EC4d for PTC were, respectively, 75%, 79%; 64%, 76% (p < 0.05); 28%, 46% (p < 0.05) and 93%, 94%. Values were similar for DSA. A noninvasive blood test, EC4d, and particularly longitudinally monitoring EC4d levels, may increase surrogate ABMR testing options.

[Chronic kidney disease: therapy and care]

Chronic kidney disease (CKD) is a major public health problem. It is therefore important to slow its progression and to treat its complications. Regardless of the causal nephropathy, arterial hypertension and proteinuria are the major progression factors of CKD. Thus, optimal control of blood pressure, reduction of proteinuria by using rennin angiotension system inhibitors can slow the progression of CKD. This effect can be enhanced by reducing sodium intake. The recent recommendations suggest that blood pressure should not be higher than 130/80 mmHg and proteinuria should not exceed 0,5 g/day. The consequences of advanced stages of the CKD have to be diagnosed and treated early: anemia, abnormal bone metabolism, hyperkalemia, fluid overload, metabolic acidosis... A particular emphasis has to be given to cardiovascular complications and risk factors. Monitoring data are well defined by the actual recommandations. Nephrologist can provide a set of recommended intervention to the primary care physician. The most accepted criterion of initiation of dialysis, in absence of clinic uremic manifestation is a glomerular filtration rate lower than 7 ml/min/1,73m2. Psychological and medical preparation of the patient to dialysis is essential. The possibility of renal transplantation should be evaluated during the following of patient with CKD

Sirolimus-based regimen is associated with decreased expression of glomerular vascular endothelial growth factor

BACKGROUND

Sirolimus (SRL) is a potent immunosuppressant used in organ transplantation. It is known to decrease vascular endothelial growth factor (VEGF) synthesis, making it an interesting treatment option for transplant patients who develop Kaposi sarcoma or other malignant diseases. Because VEGF plays a key role in glomerular function and vascular remodelling, we determined the effect of SRL on renal VEGF expression.

METHODS

Using immunohistochemistry and quantitative image analysis, we examined renal VEGF expression in routine kidney biopsies performed at 1 year post-transplant in the CONCEPT study, a prospective randomized study comparing a cyclosporine (CsA)-based regimen to a SRL-based regimen in association with mycophenolate mofetil (MMF).

RESULTS

A total of 74 patients were included in this substudy; 35 were randomized to the CsA group and 39 to the SRL group. Using continuous variables, the mean percentage of glomerular VEGF expression at Week 52 was significantly lower in the SRL group (14.7 ± 13%) compared to CsA group (21.2 ± 14%: P = 0.02). The percentage of glomerular VEGF expression at Week 52 was not influenced by recipient or donor age, gender, renal function, CsA dose, CsA blood level, SRL dose or SRL blood level. It was significantly lower in patients with a proteinuria over versus below 0.5 g/day (11.58 ± 7.9 versus 19.45 ± 15.53; P = 0.036).

CONCLUSIONS

There is emerging evidence that the VEGF system can play either a beneficial or a detrimental role depending on the specific pathologic situations. Therefore, modulating the renal VEGF axis by using an SRL-based regimen may influence the evolution of kidney injury associated with renal transplantation.