Retinal microvascular function predicts chronic kidney disease in patients with cardiovascular risk factors.

BACKGROUND AND AIMS: Endothelial dysfunction is a precursor to atherosclerosis and is implicated in the coexistence between cardiovascular disease (CVD) and chronic kidney disease (CKD). We examined whether retinal microvascular dysfunction is present in subjects with renal impairment and predictive of long-term CKD progression in patients with CVD. METHODS: In a single centre prospective observational study, 253 subjects with coronary artery disease and CVD risk factors underwent dynamic retinal vessel analysis. Retinal microvascular dysfunction was quantified by measuring retinal arteriolar and venular dilatation in response to flicker light stimulation. Serial renal function assessment was performed over a median period of 9.3 years using estimated GFR (eGFR). RESULTS: Flicker light-induced retinal arteriolar dilatation (FI-RAD) was attenuated in patients with baseline eGFR <90 mL/min/1.73 m2, compared to those with normal renal function (eGFR ≥90 mL/min/1.73 m2) (1.0 [0.4-2.1]% vs. 2.0 [0.8-3.6]%; p < 0.01). In patients with normal renal function, subjects with the lowest FI-RAD responses exhibited the greatest annual decline in eGFR. In uni- and multivariable analysis, among subjects with normal renal function, a 1% decrease in FI-RAD was associated with an accelerated decline in eGFR of 0.10 (0.01, 0.15; p = 0.03) and 0.07 mL/min/1.73 m2 per year (0.00, 0.14; p = 0.06), respectively. FI-RAD was not predictive of CKD progression in subjects with baseline eGFR <90 mL/min/1.73 m2. CONCLUSIONS: Retinal arteriolar endothelial dysfunction is present in patients with CVD who have early-stage CKD, and serves as an indicator of long-term CKD progression in those with normal renal function.

Regulated necrosis in kidney ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI) is the outcome of an inflammatory process that is triggered when an organ undergoes a transient reduction or cessation of blood flow, followed by re-establishment of perfusion. In the clinical setting, IRI contributes to significant acute kidney injury, patient morbidity and mortality, and adverse outcomes in transplantation. Tubular cell death by necrosis and apoptosis is a central feature of renal IRI. Recent research has challenged traditional views of cell death by identifying new pathways in which cells die in a regulated manner but with the morphologic features of necrosis. This regulated necrosis (RN) takes several forms, with necroptosis and ferroptosis being the best described. The precise mechanisms and relationships between the RN pathways in renal IRI are currently the subject of active research. The common endpoint of RN is cell membrane rupture, resulting in the release of cytosolic components with subsequent inflammation and activation of the immune system. We review the evidence and mechanisms of RN in the kidney following renal IRI, and discuss the use of small molecule inhibitors and genetically modified mice to better understand this process and guide potentially novel therapeutic interventions.

Paraneoplastic systemic lupus erythematosus associated with colorectal cancer.

A 64-year-old gentleman initially presented with nephrotic syndrome and membranous nephropathy with positive staining for C1q, which was suspicious for lupus membranous nephritis. Investigation led to the simultaneous diagnosis of colorectal cancer (CRC). The CRC was surgically excised and the patient's nephrotic syndrome resolved. The patient subsequently presented with classic systemic lupus erythematosus (SLE) including positive serological markers, mouth-ulcers and a photosensitive maculopapular rash. Two months later the patient represented with an SLE flare encompassing the full-hand of renal-pulmonary syndrome and vasculitic-neuropathy, importantly at this presentation occult recurrence of CRC was proven with tissue biopsy. Major histocompatibility class II haplotyping demonstrated HLA-DRB1*03, a known predisposition for SLE. This case depicts the scenario of tumour transformation triggering SLE development in a predisposed individual after an initial paraneoplastic manifestation in the form of membranous nephropathy (plus C1q). This supports the potential role of tumourgenesis in the development of SLE in a primed individual.

Application of an epitope-based allocation system in pediatric kidney transplantation.

Donor-recipient HLA mismatch remains a leading cause for sensitization and graft loss in kidney transplantation. HLA compatibility at an epitope level is emerging as an improved method of matching compared with current HLA antigen allocation. A novel epitope-based allocation approach to prospectively exclude donors with high-level mismatches was implemented for pediatric KTRs on the DD waiting list. Nineteen consecutive transplants were followed for 12 months, including eight DD KTRs listed with eplet exclusions, as well as three DD KTRs and eight LD KTRs without exclusions. KTRs with eplet exclusions had estimated GFR of 78.5 mL/min/1.73 m2 , no episodes of rejection, and time to transplant 6.55 months. HLA-A, HLA-B, HLA-DR antigen mismatches were similar between all groups. KTRs with exclusions had significantly lower class II eplet mismatches (20.4) than the contemporary DD KTRs without exclusions (63.7) and DD KTRs transplanted in the preceding decade (46.9). dnDSAs were identified in two of eight DD KTRs with exclusions, two of three DD KTRs without exclusions and five of eight LD KTRs. Epitope-based allocation achieved timely access to transplantation, low class II eplet mismatches, and low rates of dnDSAs in the first year. This strategy requires longer follow-up and larger numbers, but has the potential to reduce anti-HLA sensitization and improve both graft survival and opportunities for future retransplantation.

Foxp3+ T cells in peripheral blood of renal transplant recipients and clinical correlations.

AIM: Immunophenotype peripheral blood T cells from renal transplant recipients (RTR) using cellular markers of regulatory T cells (Tregs) and flow cytometry, including Foxp3, and correlate these findings with clinical parameters. METHODS: Expression of phenotypic markers of Tregs was assessed by flow cytometric analysis of peripheral blood lymphocytes (PBL) from (i) RTR (n = 95); (ii) patients with end-stage renal failure (ESRF) awaiting transplantation (n = 17); and (iii) normal healthy controls (n = 18). RESULTS: The percentage of CD4(+) CD25(+) Foxp3(+) cells within the CD4(+) cell population did not significantly alter at different time points post-transplant. However, the percentage of CD4(+) CD25(+) Foxp3(+) cells within the CD4(+) population was significantly lower in RTR compared with patients with ESRF. In contrast, RTR and ESRF had a similar percentage of CD4(+) CD25(+) cells expressing Foxp3. Multivariate analysis of PBL and clinical parameters demonstrated (i) a positive linear relationship between the percentage CD4(+) CD25(+) cells expressing Foxp3 and estimated glomerular filtration rate and (ii) a higher percentage of CD4(+) CD25(+) cells in the CD4(+) cell population in patients with malignancy (the majority were skin cancers). Malignancy also correlated strongly with time post-transplant and age of the RTR. CONCLUSION: Immune monitoring of the PBL phenotype in RTR using CD4, CD25 and Foxp3 may stratify RTR and predict graft outcome and function, and risk of complications from immunosuppression. Longitudinal and functional studies of Tregs are essential to extend the findings of the present study.

Impact of chronic kidney disease on patient outcome following cardiac surgery.

BACKGROUND: Renal impairment is a major risk factor for cardiovascular disease. This study addressed clinical predictors of outcome following cardiac surgery, focusing on pre-operative renal dysfunction. METHODS: All patients undergoing cardiac surgery at Austin Health from June 1, 2001 to June 30, 2006, were included in the analysis. Logistic regression models were used to evaluate clinical factors predicting "operative mortality" and common post-operative complications. RESULTS: The operative mortality was 1.36% for coronary artery bypass grafting (CABG) alone (n=1027), 5.07% for valve surgery alone (n=217), 4.43% for combined CABG and valve surgery (n=158) and 11.11% for other cardiac surgical procedures (n=270). Amongst CABG alone patients, pre-operative renal impairment was a strong predictor of operative mortality, with a 35-43% increased risk of death (p=0.005) for every 10 ml/min/1.73 m(2) that the glomerular filtration rate was lower. Peripheral vascular disease, recent myocardial infarction and congestive cardiac failure also predicted operative mortality. Pre-operative renal impairment also increased the rate of various post-operative complications, as well as duration of admission. CONCLUSION: Renal dysfunction is significantly associated with increased mortality and morbidity following cardiac surgery and necessitates careful consideration in risk benefit analysis when considering cardiac surgery.

Local expression of IDO, either alone or in combination with CD40Ig, IL10 or CTLA4Ig, inhibits indirect xenorejection responses.

BACKGROUND: To overcome cell-mediated xenorejection by transgenic expression of immunomodulatory molecules by a graft, it is likely that expression of multiple molecules will be required. Previous studies support the use of the immunomodulatory agents indoleamine 2,3-dioxygenase (IDO), CD40Ig, interleukin 10 (IL10), and CTLA4Ig for suppression of rejection responses. We examined the effects of local expression of these molecules by a porcine cell line (PIEC) on indirect murine xenorejection responses in vitro and in vivo. METHODS: The PIEC stable lines expressing IDO, CD40Ig, and IL10 as single molecules were generated. In addition, PIEC lines expressing IDO with either CD40Ig, IL10 or CTLA4Ig were generated to produce cell lines expressing two molecules. BALB/c mice were primed with wild type PIEC, followed by harvesting splenocytes used as responder cells and PIEC expressing immunomodulatory molecules as stimulators, in proliferation and cytokine assays. In vivo effects of modified PIEC were examined by transplantation of PIEC lines expressing the immunomodulatory molecules under the renal capsule of naïve mice. PIEC grafts were harvested for histological evaluation at days 7 and 14. RESULTS: Proliferation of primed BALB/c splenocytes was inhibited most significantly by IDO compared with control cells (49%, P = 0.02). In addition both Th1 (interferon-gamma) and Th2 (IL4 and IL10) cytokines were markedly inhibited in vitro by IDO expression. IL10 expressing cells did not inhibit proliferation as potently (37%, P = 0.03) whilst CD40Ig lead to an increase in proliferative responses (59%, P = 0.02). Co-expression of CD40Ig, IL10, and CTLA4Ig with IDO resulted in further modest reductions in proliferation compared with IDO expression alone. When transplanted under the renal capsule of BALB/c mice, those grafts expressing IDO demonstrated significantly lower levels of lymphocyte infiltration at days 7 and 14 than control grafts and those expressing CD40Ig, CTLA4Ig or IL10 alone. Grafts co-expressing IDO and a second molecule were no better protected than those expressing IDO alone. Graft cell viability (PIECs) was reduced in some IDO expressing grafts suggesting high levels of IDO expression may inhibit PIEC viability, however, grafts co-expressing IDO-CTLA4Ig and IDO-IL10 were not affected in this way. CONCLUSION: Indoleamine 2,3-dioxygenase appears to be a potent molecule for protecting xenografts from cell-mediated rejection responses activated via the indirect pathway. Co-expression of IDO with both CTLA4Ig and IL10 warrants further investigation. Overall these findings support pursuing further studies, in larger animal models, to determine whether increased IDO activity within the graft itself can attenuate xenorejection responses.

Predictors of early dialysis vascular-access failure after thrombolysis.

BACKGROUND: Vascular-access patency is critical for effective and uninterrupted haemodialysis. Limited literature exists evaluating if a surgical or repeated radiological approach is superior for reocclusion following failure of radiological recanalization. Few consistent early predictors of failure have been identified after radiological intervention for thrombosed vascular access. METHODS: 138 patients with thrombosed arteriovenous fistulas or prosthetic grafts treated by radiological intervention, over 10 years, were retrospectively investigated. Reocclusion was treated by either repeated thrombolysis or surgery. Radiological patency rates, after first and second episodes of access thrombosis at 12 months after intervention were analysed. Surgical and radiological patency rates for second access thrombosis were compared. The Cox and logistic regression models were used to identify potential factors associated with reocclusion. RESULTS: In patients who experienced reocclusion within 1 month after radiological intervention, the 3-month repeated radiological patency rate (n = 13) was 38.5%, compared to a 60% surgical patency rate (n = 10), but this did not reach statistical significance. Radiological patency rates after first access thrombosis at 3 and 12 months were 56.6 and 39.5%, respectively. In contrast, radiological patency rates after a second access thrombosis were 51.1 and 24.4%, respectively; a statistical difference in success was not achieved. Native arteriovenous fistulas were 3.23 times as likely to remain patent over 12 months following a first radiological intervention (p < 0.02) and less likely to experience a second reocclusion event (p < 0.01). Anticoagulation was associated with a lower risk of second reocclusion, whilst a history of venous thrombosis was associated with a greater risk (p < 0.02). CONCLUSION: Surgery achieves superior patency rates compared to repeated radiological interventions and should be considered if reocclusion occurs within a month following radiological thrombolysis.

Intravesical fat entrapment as a cause of failure of extraperitoneal bladder perforation to heal spontaneously.

We report a case of intravesical fat entrapment leading to failure of extraperitoneal bladder perforation to heal spontaneously. A 68-year-old woman underwent trans-abdominal hysterectomy complicated by an extraperitoneal bladder perforation. Despite prolonged catheterization, cystographic leakage persisted after 3 months. Bladder imaging and cystoscopy demonstrated a mass of perivesical pelvic fat protruding into the bladder cavity. The patient was symptomatic with pain and persistent urinary tract infection with episodes of sepsis. A transurethral resection of the mass was performed which led to bladder healing and resolution of symptoms.

Development of an anti-porcine CD34 monoclonal antibody that identifies hematopoietic stem cells.

OBJECTIVES: The isolation of porcine hematopoietic stem cells (HSC) would be an important step toward development of porcine-to-human chimerism for induction of tolerance in clinical xenotransplantation. CD34 is a common marker of HSC and has not been developed as a marker in pigs. In this study we have generated and characterized a monoclonal antibody (mAb) that identifies porcine CD34 on a subset of porcine bone marrow (BM) stem/progenitor cells. METHODS: The porcine CD34 gene was cloned and a recombinant protein produced. An anti-porcine CD34 mAb was produced that could detect both the recombinant protein and a subset of porcine BM cells. The CD34(+) cells were phenotyped by lineage and HSC associated markers. Furthermore, the CD34(+) cells were analyzed by colony-forming unit (CFU) assay. RESULTS: Two splice variants of the porcine CD34 gene were cloned and a recombinant protein produced for mAb production. The mAb developed can detect both the recombinant protein and the native CD34 protein on a range of pig tissues, including BM. This subset of BM cells was negative for hematopoietic lineage makers, including CD3, CD14, and CD21 and positive for other known porcine HSC markers, including CD90, CD172a, histocompatibility complex (MHC) class I, and MHC class II. Moreover, the CD34(+) BM cells were enriched for multilineage progenitor cells as determined by CFU assay. CONCLUSIONS: Similar to human and mouse CD34, pig CD34 detects a subset of BM progenitor cells. This mAb will now provide a means for isolating porcine CD34(+) cells to be further analyzed for HSC activity and to assess their potential to develop pig-to-human chimeras to induce xenograft tolerance.

Cardiovascular biomarkers in CKD: pathophysiology and implications for clinical management of cardiac disease.

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with all forms of chronic kidney disease (CKD). The underlying pathological state is caused by a complex interplay of traditional and nontraditional risk factors that results in atherosclerosis, arteriosclerosis, and altered cardiac morphological characteristics. This multifactorial disease introduces new challenges in predicting and treating patients with CVD sufficiently early in the course of CKD to positively alter patient outcome. Asymptomatic individuals with progressive CVD are a group of patients that deserve focused attention because early detection and intervention may provide the best opportunity for improved outcome. However, identifying CVD in asymptomatic patients with CKD or end-stage renal disease remains a significant hurdle in the management of these patients. Recently, a number of cardiovascular biomarkers were identified as predictors of patient outcome in individuals with CVD and, with additional research, may be used to guide the early diagnosis of and therapy for CVD in patients with CKD. This review examines the pathophysiological characteristics and potential clinical role of these novel cardiovascular biomarkers in risk stratification, risk monitoring, and selection of preventive therapies for patients with CKD.

Severe renal failure and nephrocalcinosis in anorexia nervosa.

Two patients with anorexia nervosa and raised serum creatinine levels were found to have nephrocalcinosis on renal biopsy, an association not previously described.

Cystatin C for estimation of glomerular filtration rate in patients with spinal cord injury.

BACKGROUND: Serum creatinine is not a satisfactory marker of glomerular filtration rate (GFR) in patients with spinal cord injury (SCI) who have varying degrees of muscle atrophy. In contrast to serum creatinine, serum cystatin C, a 13-kDa protein, is not affected by muscle mass and is therefore potentially a useful marker of GFR in patients with SCI. In addition, cystatin C is not dependent on sex or age and is not secreted by the renal tubule. AIM: We assessed serum cystatin C as a surrogate marker of GFR in SCI patients. METHODS: Cystatin C was analysed using a particle-enhanced immunonephelometric assay (Dade Behring) in serum samples sent for routine measurement of creatinine (64 patients) and creatinine clearance (27 patients) from patients in the Spinal Unit of the Austin Health. We compared these results with serum cystatin C of 57 non-SCI patients who had had a creatinine clearance measurement during the study period. RESULTS: In patients with SCI, the reciprocal of cystatin C had a stronger correlation (r = 0.48, P<0.01) with creatinine clearance than the reciprocal of serum creatinine (r = 0.25, P<0.19). Further, the value of serum creatinine was much lower for a given creatinine clearance in SCI patients than in non-SCI patients; the serum cystatin C concentrations were equivalent. CONCLUSION: The serum cystatin C is a convenient and more reliable surrogate marker of GFR than serum creatinine and will enable early detection of renal impairment. We need to confirm this finding with a larger study, including comparison with an accepted gold standard for GFR.