Characteristics of AA amyloidosis patients in San Francisco.

BACKGROUND: AA amyloidosis due to subcutaneous injection of drugs of abuse has been described in the USA, but all the existing literature is from more than 20 years ago. There is more recent literature from Europe. We have observed a high incidence of AA amyloidosis in the county hospital in San Francisco. DESIGN: Here, we describe 24 patients who had kidney biopsy-proven AA amyloidosis from our hospital from 1998 to 2013. All the patients were thought to have AA amyloidosis from skin popping of illicit drugs after having exhausted the intravenous route. These patients with biopsy-proven AA amyloidosis were analysed further. RESULTS: All patients were found to have hepatitis C infection, hypertension was not common, most had advanced kidney failure, and acidosis was common as was tubulointerstitial involvement on the kidney biopsy. Other organ involvement included hepatomegaly and splenomegaly in a number of patients; direct myocardial involvement was not seen, but pulmonary hypertension, history of deep vein thrombosis and pulmonary embolism were common. The prognosis of these patients was poor. The mortality rate approached 50% 1 year after biopsy, and most of the patient needed dialysis shortly after diagnosis. Cessation of drug use seemed beneficial but rarely achievable. CONCLUSION: AA amyloidosis from skin popping is common in San Francisco. Most patients with renal involvement end up on dialysis, and mortality rates are exceedingly high.

The Endoplasmic Reticulum Resident Protein AGR3. Required for Regulation of Ciliary Beat Frequency in the Airway.

Protein disulfide isomerase (PDI) family members regulate protein folding and calcium homeostasis in the endoplasmic reticulum (ER). The PDI family member anterior gradient (AGR) 3 is expressed in the airway, but the localization, regulation, and function of AGR3 are poorly understood. Here we report that AGR3, unlike its closest homolog AGR2, is restricted to ciliated cells in the airway epithelium and is not induced by ER stress. Mice lacking AGR3 are viable and develop ciliated cells with normal-appearing cilia. However, ciliary beat frequency was lower in airways from AGR3-deficient mice compared with control mice (20% lower in the absence of stimulation and 35% lower after ATP stimulation). AGR3 deficiency had no detectable effects on ciliary beat frequency (CBF) when airways were perfused with a calcium-free solution, suggesting that AGR3 is required for calcium-mediated regulation of ciliary function. Decreased CBF was associated with impaired mucociliary clearance in AGR3-deficient airways. We conclude that AGR3 is a specialized member of the PDI family that plays an unexpected role in the regulation of CBF and mucociliary clearance in the airway.

Independent state health surveys: responding to the need for local population health data.

CONTEXT: There is high demand for local-level population health data. A national system of state and local data collection would help improve both population health and health care delivery. The primary source of state-level population health data for adults is the Behavioral Risk Factor Surveillance System. However, many states need data on children and adolescents, racial and ethnic subpopulations, consistent estimates for localities, or more in-depth information on key topics than the Behavioral Risk Factor Surveillance System provides. Eleven state health surveys (SHSs) have emerged in an effort to address these gaps. DESIGN: Semistructured telephone interviews were conducted in 2009 with representatives of 9 SHSs. The interviews were recorded, and data were transcribed, organized, and analyzed according to the query structure. This analysis identified (1) the core elements of SHS that have been successful in meeting needs for local data and (2) the processes and strategies used by state officials in creating these surveys. RESULTS: Key findings include the following: (1) SHSs provide concrete data on local health issues that meet the needs of policy makers who wish to adopt evidence-based public health policies; (2) data from SHSs allow researchers to identify issues, apply for grants, and evaluate, assess, and track health indicators; (3) a "champion" is required to build the case for a survey and push through barriers to obtain funding and stakeholder buy-in; and (4) SHSs face challenges such as inconsistent funding and lack of uniform standards. CONCLUSION: Opportunities to support SHSs include (1) identifying sustained funding sources; (2) providing technical assistance and facilitating training to foster best practices, quality standards, and comparability across states; and (3) supporting an organization for SHS researchers to share resources, information, and experiences.

Epoxyeicosatrienoic acids prevent cisplatin-induced renal apoptosis through a p38 mitogen-activated protein kinase-regulated mitochondrial pathway.

Soluble epoxide hydrolase (sEH) catalyzes the conversion of epoxyeicosatrienoic acids into less active eicosanoids, and inhibitors of sEH have anti-inflammatory and antiapoptotic properties. Based on previous observations that sEH inhibition attenuates cisplatin-induced nephrotoxicity by modulating nuclear factor-κB signaling, we hypothesized that this strategy would also attenuate cisplatin-induced renal apoptosis. Inhibition of sEH with AR9273 [1-adamantan-1-yl-3-(1-methylsulfonyl-piperidin-4-yl-urea)] reduced cisplatin-induced apoptosis through mechanisms involving mitochondrial apoptotic pathways and by reducing reactive oxygen species. Renal mitochondrial Bax induction following cisplatin treatment was significantly decreased by treatment of mice with AR9273 and these antiapoptotic effects involved p38 mitogen-activated protein kinase signaling. Similar mechanisms contributed to reduced apoptosis in Ephx2(-/-) mice treated with cisplatin. Moreover, in pig kidney proximal tubule cells, cisplatin-induced mitochondrial trafficking of Bax and cytochrome c, caspase-3 activation, and oxidative stress are significantly attenuated in the presence of epoxyeicosatrienoic acids (EETs). Collectively, these in vivo and in vitro studies demonstrate a role for EETs in limiting cisplatin-induced renal apoptosis. Inhibition of sEH represents a novel therapeutic strategy for protection against cisplatin-induced renal damage.

Outcomes of kidney transplantation in HIV-infected recipients.

BACKGROUND: The outcomes of kidney transplantation and immunosuppression in people infected with human immunodeficiency virus (HIV) are incompletely understood. METHODS: We undertook a prospective, nonrandomized trial of kidney transplantation in HIV-infected candidates who had CD4+ T-cell counts of at least 200 per cubic millimeter and undetectable plasma HIV type 1 (HIV-1) RNA levels while being treated with a stable antiretroviral regimen. Post-transplantation management was provided in accordance with study protocols that defined prophylaxis against opportunistic infection, indications for biopsy, and acceptable approaches to immunosuppression, management of rejection, and antiretroviral therapy. RESULTS: Between November 2003 and June 2009, a total of 150 patients underwent kidney transplantation; survivors were followed for a median period of 1.7 years. Patient survival rates (±SD) at 1 year and 3 years were 94.6±2.0% and 88.2±3.8%, respectively, and the corresponding mean graft-survival rates were 90.4% and 73.7%. In general, these rates fall somewhere between those reported in the national database for older kidney-transplant recipients (≥65 years) and those reported for all kidney-transplant recipients. A multivariate proportional-hazards analysis showed that the risk of graft loss was increased among patients treated for rejection (hazard ratio, 2.8; 95% confidence interval [CI], 1.2 to 6.6; P=0.02) and those receiving antithymocyte globulin induction therapy (hazard ratio, 2.5; 95% CI, 1.1 to 5.6; P=0.03); living-donor transplants were protective (hazard ratio, 0.2; 95% CI, 0.04 to 0.8; P=0.02). A higher-than-expected rejection rate was observed, with 1-year and 3-year estimates of 31% (95% CI, 24 to 40) and 41% (95% CI, 32 to 52), respectively. HIV infection remained well controlled, with stable CD4+ T-cell counts and few HIV-associated complications. CONCLUSIONS: In this cohort of carefully selected HIV-infected patients, both patient- and graft-survival rates were high at 1 and 3 years, with no increases in complications associated with HIV infection. The unexpectedly high rejection rates are of serious concern and indicate the need for better immunotherapy. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00074386.).

States' use of local population health data: comparing the Behavioral Risk Factor Surveillance System and independent state health surveys.

OBJECTIVES: To identify and compare key features of independent comprehensive state health surveys (SHS) with those of the Behavioral Risk Factor Surveillance System (BRFSS) for addressing the need for statewide and local population health data. METHODS: We developed inclusion criteria, systematically collected information about federal and SHS that met these criteria, and obtained supplemental information from SHS leaders. RESULTS: We identified comprehensive independent SHS in 11 states and BRFSS surveys in all 50 states. The independent SHS meet important statewide and local data needs, filling 3 key health data gaps in the BRFSS: lack of adequate data on special populations such as children, lack of data on specific localities, and limited depth and scope of health topics surveyed on key issues such as health insurance coverage. Unlike BRFSS, independent SHS have limited comparability with each other. CONCLUSIONS: The BRFSS and independent SHS each meet some key state and local data needs but result in data gaps and inefficient use of resources. Surveys could more effectively and efficiently meet future needs for comparable data to monitor health care reform and address health disparities if they were coordinated across states and at the national, state, and local levels.

Attenuation of cisplatin-induced renal injury by inhibition of soluble epoxide hydrolase involves nuclear factor κB signaling.

Acute kidney injury is associated with a significant inflammatory response that has been the target of renoprotection strategies. Epoxyeicosatrienoic acids (EETs) are anti-inflammatory cytochrome P450-derived eicosanoids that are abundantly produced in the kidney and metabolized by soluble epoxide hydrolase (sEH; Ephx2) to less active dihydroxyeicosatrienoic acids. Genetic disruption of Ephx2 and chemical inhibition of sEH were used to test whether the anti-inflammatory effects of EETs, and other lipid epoxide substrates of sEH, afford protection against cisplatin-induced nephrotoxicity. EET hydrolysis was significantly reduced in Ephx2(-/-) mice and was associated with an attenuation of cisplatin-induced increases in serum urea nitrogen and creatinine levels. Histological evidence of renal tubular damage and neutrophil infiltration was also reduced in the Ephx2(-/-) mice. Likewise, cisplatin had no effect on renal function, neutrophil infiltration, or tubular structure and integrity in mice treated with the potent sEH inhibitor 1-adamantan-1-yl-3-(1-methylsulfonyl-piperidin-4-yl-urea) (AR9273). Consistent with the ability of EETs to interfere with nuclear factor-κB (NF-κB) signaling, the observed renoprotection was associated with attenuation of renal NF-κB activity and corresponding decreases in the expression of tumor necrosis factor (TNF) α, TNF receptor (TNFR) 1, TNFR2, and intercellular adhesive molecule-1 before the detection of tubular injury. These data suggest that EETs or other fatty acid epoxides can attenuate cisplatin-induced kidney injury and sEH inhibition is a novel renoprotective strategy.

Matrix metalloproteinase 2 and basement membrane integrity: a unifying mechanism for progressive renal injury.

Chronic kidney disease (CKD) and failure are problems of increasing importance. Regardless of the primary etiology, CKD is characterized by tubular atrophy, interstitial fibrosis, and glomerulosclerosis. It has been assumed that diminished matrix metalloproteinase (MMP) activity is responsible for the accumulation of the extracellular matrix (ECM) proteins and collagens that typify the fibrotic kidney. Here we demonstrate that transgenic renal proximal tubular epithelial expression of a specific enzyme, MMP-2, is sufficient to generate the entire spectrum of pathological and functional changes characteristic of human CKD. At the earliest point, MMP-2 leads to structural alterations in the tubular basement membrane, a process that triggers tubular epithelial-mesenchymal transition, with resultant tubular atrophy, fibrosis and renal failure. Inhibition of MMP-2, specifically in the early, prefibrotic stages of disease may offer an additional approach for treatment of these disabling disorders.

Legacy of MESA.

The MESA (Multi-Ethnic Study of Atherosclerosis) was initiated to address unresolved questions about subclinical cardiovascular disease and its progression to clinically overt cardiovascular disease in a diverse population-based sample, incorporating emerging imaging technologies for better evaluation of subclinical disease and creating a population laboratory for future research. MESA's recruited (from 2000 to 2002) cohort comprised >6,000 adults from 4 racial/ethnic groups, ages 45 to 84 years, who were free of cardiovascular disease at baseline. Extensive cohort data have been collected over 5 exams (through 2011) with additional exam components added through extramurally funded ancillary study grants, and through regular phone follow-up contacts. Over 1,000 MESA papers have been published to date. Exam 6 will incorporate components that use novel wearable, imaging, and other technologies to address new research questions. MESA investigators have and continue to seek opportunities for collaboration with other researchers on a wide variety of topics to further expand the science of MESA.

A novel human autoimmune syndrome caused by combined hypomorphic and activating mutations in ZAP-70.

A brother and sister developed a previously undescribed constellation of autoimmune manifestations within their first year of life, with uncontrollable bullous pemphigoid, colitis, and proteinuria. The boy had hemophilia due to a factor VIII autoantibody and nephrotic syndrome. Both children required allogeneic hematopoietic cell transplantation (HCT), which resolved their autoimmunity. The early onset, severity, and distinctive findings suggested a single gene disorder underlying the phenotype. Whole-exome sequencing performed on five family members revealed the affected siblings to be compound heterozygous for two unique missense mutations in the 70-kD T cell receptor ζ-chain associated protein (ZAP-70). Healthy relatives were heterozygous mutation carriers. Although pre-HCT patient T cells were not available, mutation effects were determined using transfected cell lines and peripheral blood from carriers and controls. Mutation R192W in the C-SH2 domain exhibited reduced binding to phosphorylated ζ-chain, whereas mutation R360P in the N lobe of the catalytic domain disrupted an autoinhibitory mechanism, producing a weakly hyperactive ZAP-70 protein. Although human ZAP-70 deficiency can have dysregulated T cells, and autoreactive mouse thymocytes with weak Zap-70 signaling can escape tolerance, our patients' combination of hypomorphic and activating mutations suggested a new disease mechanism and produced previously undescribed human ZAP-70-associated autoimmune disease.

Acute felbamate overdose with crystalluria.

A 3-year-old child developed vomiting, ataxia, and crystalluria after ingestion of approximately 232 mg/kg of felbamate elixir. High-powered polarization microscopy of the urine revealed sharp, needle-like crystals. The analysis of the urine crystals showed unchanged felbamate (80.9%), monocarbamate felbamate (18.8%), and trace amounts of mercapturic acid conjugates of the metabolite 2-phenylpropenal (0.1%). The serum felbamate level 15 h after ingestion was 138 mg/L. Crystalluria and hematuria resolved with intravenous fluid therapy, and the child recovered within 24 h.

Two Distinct Isoforms of Matrix Metalloproteinase-2 Are Associated with Human Delayed Kidney Graft Function.

Delayed graft function (DGF) is a frequent complication of renal transplantation, particularly in the setting of transplantation of kidneys derived from deceased donors and expanded-criteria donors. DGF results from tubular epithelial cell injury and has immediate and long term consequences. These include requirement for post-transplantation dialysis, increased incidence of acute rejection, and poorer long-term outcomes. DGF represents one of the clearest clinical examples of renal acute ischemia/reperfusion injury. Experimental studies have demonstrated that ischemia/reperfusion injury induces the synthesis of the full length secreted isoform of matrix metalloproteinase-2 (FL-MMP-2), as well as an intracellular N-terminal truncated MMP-2 isoform (NTT-MMP-2) that initiates an innate immune response. We hypothesized that the two MMP-2 isoforms mediate tubular epithelial cell injury in DGF. Archival renal biopsy sections from 10 protocol biopsy controls and 41 cases with a clinical diagnosis of DGF were analyzed for the extent of tubular injury, expression of the FL-MMP-2 and NTT-MMP-2 isoforms by immunohistochemistry (IHC), in situ hybridization, and qPCR to determine isoform abundance. Differences in transcript abundance were related to tubular injury score. Markers of MMP-2-mediated injury included TUNEL staining and assessment of peritubular capillary density. There was a clear relationship between tubular epithelial cell expression of both FL-MMP-2 and NTT-MMP-2 IHC with the extent of tubular injury. The MMP-2 isoforms were detected in the same tubular segments and were present at sites of tubular injury. qPCR demonstrated highly significant increases in both the FL-MMP-2 and NTT-MMP-2 transcripts. Statistical analysis revealed highly significant associations between FL-MMP-2 and NTT-MMP-2 transcript abundance and the extent of tubular injury, with NTT-MMP-2 having the strongest association. We conclude that two distinct MMP-2 isoforms are associated with tubular injury in DGF and offer novel therapeutic targets for the prevention of this disorder.

Dietary phosphorus transcriptionally regulates 25-hydroxyvitamin D-1alpha-hydroxylase gene expression in the proximal renal tubule.

Synthesis of the hormone 1,25-dihydroxyvitamin D, the biologically active form of vitamin D, occurs in the kidney and is catalyzed by the mitochondrial cytochrome P450 enzyme, 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase). We sought to characterize the effects of changes in dietary phosphorus on the kinetics of renal mitochondrial 1alpha-hydroxylase activity and the renal expression of P450c1alpha and P450c24 mRNA, to localize the nephron segments involved in such regulation, and to determine whether transcriptional mechanisms are involved. In intact mice, restriction of dietary phosphorus induced rapid, sustained, approximately 6- to 8-fold increases in renal mitochondrial 1alpha-hydroxylase activity and renal P450c1alpha mRNA abundance. Immunohistochemical analysis of renal sections from mice fed the control diet revealed the expression of 1alpha-hydroxylase protein in the proximal convoluted and straight tubules, epithelial cells of Bowman's capsule, thick ascending limb of Henle's loop, distal tubule, and collecting duct. In mice fed a phosphorus-restricted diet, immunoreactivity was significantly increased in the proximal convoluted and proximal straight tubules and epithelial cells of Bowman's capsule, but not in the distal nephron. Dietary phosphorus restriction induced a 2-fold increase in P450c1alpha gene transcription, as shown by nuclear run-on assays. Thus, the increase in renal synthesis of 1,25-dihydroxyvitamin D induced in normal mice by restricting dietary phosphorus can be attributed to an increase in the renal abundance of P450c1alpha mRNA and protein. The increase in P450c1alpha gene expression, which occurs exclusively in the proximal renal tubule, is due at least in part to increased transcription of the P450c1alpha gene.

Sirolimus delays recovery of rat kidney transplants after ischemia-reperfusion injury.

BACKGROUND: Sirolimus (SRL) seems to impair renal recovery from ischemic injury in animal models and delayed graft function after clinical renal transplantation. This study determined the impact of SRL on renal recovery after ischemia-reperfusion injury in a rat kidney transplant model. METHODS: Syngeneic kidneys were preserved in University of Wisconsin solution before transplantation into bilaterally nephrectomized rats. Recipients received vehicle or SRL targeting for whole-blood trough levels of 10 to 20 ng/mL as measured by high-performance liquid chromatography. Renal function was assessed by animal survival or daily serum creatinine. Tissue samples were collected for histologic examination. RESULTS: Median SRL whole-blood concentrations were 16.6 +/- 1.6 ng/mL on postoperative day (POD) 1 and 12.0 +/- 0.9 ng/mL on POD 3. Transplantation of kidneys after 39 hr of cold storage resulted in 30% survival in the SRL-treated group compared with 100% survival in the control group (P=0.002). Transplantation of kidneys after 24 hr of cold storage resulted in no survival differences, but there were significant differences in renal function. Daily serum creatinine (PODs 1-4) was higher in the SRL-treated group compared with the control group (P<0.05 at all time points). Grafts from SRL-treated animals showed more severe tubular necrosis compared with control animals. CONCLUSIONS: When given at therapeutic immunosuppressive doses, SRL compromises renal function after ischemia-reperfusion injury in a rat kidney transplant model. The antiproliferative effect of SRL may translate into impairment of tubular repair and regeneration necessary for recovery after such injury.

Characterization of blood pressure and morphological traits in cardiovascular-related organs in 13 different inbred mouse strains.

To better understand the contributions of various genetic backgrounds to complex quantitative phenotypes, we have measured several quantitative traits of cardiovascular interest [i.e., systolic blood pressure, weight (corrected by body weight) of several cardiac compartments and adrenals and kidneys, and histological correlates for kidneys and adrenals] in male and female mice from 13 different inbred strains. We selected strains so that each major genealogical group would be represented and to conform to priorities set by the Mouse Phenome Database project. Interstrain comparisons of phenotypes made it possible to identify strains that displayed values that belonged to either the low or the high end of the interstrain variance for quantitative traits, such as systolic blood pressure, body weight, left ventricular weight, and/or adrenocortical structure. For instance, both male and female C3H/HeJ and A/J mice displayed either low systolic blood pressure or low cardiac ventricular mass, respectively, and male C57BL6/J displayed low adrenal weight. Likewise, intersex comparisons made it possible to identify phenotypic values that were sexually dimorphic for some of the same traits. For instance, female AKR/J mice had relatively higher body weight and systolic blood pressure values than their male counterparts, perhaps constituting an animal model of the metabolic X syndrome. These strain- and sex-specific features will be of value both for future genetic and/or developmental studies and for the development of new animal models that will help in the generation of mechanistic hypotheses. All data have been deposited to the Mouse Phenome Database for future integration with the Mouse Genome Database and can be further analyzed and compared with tools available on the site.

Hormone replacement therapy and the risk of incident congestive heart failure: the Cardiovascular Health Study.

BACKGROUND: The development of congestive heart failure (CHF) in older persons is related to a variety of mechanisms. Hormone replacement therapy (HRT) affects several of the pathways that may be important in the development of CHF. We hypothesized that HRT would be associated with a decreased risk of incident CHF. METHODS: Using Cox proportional-hazards regression, we assessed the risk of incident CHF (n = 304) associated with time-dependent past and current use of HRT compared to never use. The Cardiovascular Health Study is a prospective cohort study of community-dwelling adults aged 65 years and older. This analysis included female participants without a history of CHF at baseline (n = 3223). RESULTS: At baseline, 62% were never users, 26% were past users, and 12% were current users of HRT. Compared with never users, the multivariable relative risk (RR) of CHF was 1.01 (95% confidence interval [95% CI] 0.76,1.34) for past users and 1.34 (0.93,1.94) for current users. Results were similar among most treatment and clinical subgroups, except that the association of current HRT with CHF appeared to depend on body mass index (BMI) or osteoporosis status. The RR was 0.82 (0.43,1.60) for normal weight women, 1.65 (0.95,2.88) for overweight women, and 2.22 (1.06,4.67) for obese women (p = 0.01 for interaction). Similarly, the RR was 0.15 (0.04,0.65) for women with osteoporosis and 1.82 (1.25,2.65) for women without osteoporosis (p = 0.001 for interaction). CONCLUSIONS: Overall, HRT was not associated with the risk of incident CHF, although BMI and osteoporosis appeared to modify the association of HRT with CHF. The risk of CHF was lower in patients with lower BMI or osteoporosis.

Race/ethnicity and disease severity in IgA nephropathy.

BACKGROUND: Relatively few U.S.-based studies in chronic kidney disease have focused on Asian/Pacific Islanders. Clinical reports suggest that Asian/Pacific Islanders are more likely to be affected by IgA nephropathy (IgAN), and that the severity of disease is increased in these populations. METHODS: To explore whether these observations are borne out in a multi-ethnic, tertiary care renal pathology practice, we examined clinical and pathologic data on 298 patients with primary glomerular lesions (IgAN, focal segmental glomerulosclerosis, membranous nephropathy and minimal change disease) at the University of California San Francisco Medical Center from November 1994 through May 2001. Pathologic assessment of native kidney biopsies with IgAN was conducted using Haas' classification system. RESULTS: Among individuals with IgAN (N = 149), 89 (60%) were male, 57 (38%) white, 53 (36%) Asian/Pacific Islander, 29 (19%) Hispanic, 4 (3%) African American and 6 (4%) were of other or unknown ethnicity. The mean age was 37 +/- 14 years and median serum creatinine 1.7 mg/dL. Sixty-six patients (44%) exhibited nephrotic range proteinuria at the time of kidney biopsy. The distributions of age, gender, mean serum creatinine, and presence or absence of nephrotic proteinuria and/or hypertension at the time of kidney biopsy were not significantly different among white, Hispanic, and Asian/Pacific Islander groups. Of the 124 native kidney biopsies with IgAN, 10 (8%) cases were classified into Haas subclass I, 12 (10%) subclass II, 23 (18%) subclass III, 30 (25%) subclass IV, and 49 (40%) subclass V. The distribution of Haas subclass did not differ significantly by race/ethnicity. In comparison, among the random sample of patients with non-IgAN glomerular lesions (N = 149), 77 (52%) patients were male, 51 (34%) white, 42 (28%) Asian/Pacific Islander, 25 (17%) Hispanic, and 30 (20%) were African American. CONCLUSIONS: With the caveats of referral and biopsy biases, the race/ethnicity distribution of IgAN differs significantly from that of other major glomerulonephridities. However, among individuals undergoing native kidney biopsy, we see no evidence of a race/ethnicity association with severity of disease in IgAN by clinical and IgAN-specific histopathologic criteria. Further studies are needed to identify populations at higher risk for progressive disease in IgAN.

Reliability of whole slide images as a diagnostic modality for renal allograft biopsies.

The use of digital whole slide images (WSI) in the field of pathology has become feasible for routine diagnostic purposes and has become more prevalent in recent years. This type of technology offers many advantages but must show the same degree of diagnostic reliability as conventional glass slides. Several studies have examined this issue in various settings and indicate that WSI are a reliable method for diagnostic pathology. Since transplant pathology is a highly specialized field that requires not only accurate but rapid diagnostic evaluation of biopsy materials, this field may greatly benefit from the use of WSI. In this study, we assessed the reliability of using WSI compared to conventional glass slides in renal allograft biopsies. We examined morphologic features and diagnostic categories defined by the Banff 07 Classification of Renal Allograft Pathology as well as additional morphologic features not included in this classification scheme. We found that intraobserver scores, when comparing the use of glass slides versus WSI, showed substantial agreement for both morphologic features (κ = 0.68) and acute rejection diagnostic categories (κ = 0.74). Furthermore, interobserver reliability was comparable for morphologic features (κ = 0.44 [glass] vs 0.42 [WSI]) and acute rejection diagnostic categories (κ = 0.49 [glass] vs 0.51 [WSI]). These data indicate that WSI are as reliable as glass slides for the evaluation of renal allograft biopsies.

Reversible cell-cycle entry in adult kidney podocytes through regulated control of telomerase and Wnt signaling.

Mechanisms of epithelial cell renewal remain poorly understood in the mammalian kidney, particularly in the glomerulus, a site of cellular damage in chronic kidney disease. Within the glomerulus, podocytes--differentiated epithelial cells crucial for filtration--are thought to lack substantial capacity for regeneration. Here we show that podocytes rapidly lose differentiation markers and enter the cell cycle in adult mice in which the telomerase protein component TERT is conditionally expressed. Transgenic TERT expression in mice induces marked upregulation of Wnt signaling and disrupts glomerular structure, resulting in a collapsing glomerulopathy resembling those in human disease, including HIV-associated nephropathy (HIVAN). Human and mouse HIVAN kidneys show increased expression of TERT and activation of Wnt signaling, indicating that these are general features of collapsing glomerulopathies. Silencing transgenic TERT expression or inhibiting Wnt signaling through systemic expression of the Wnt inhibitor Dkk1 in either TERT transgenic mice or in a mouse model of HIVAN results in marked normalization of podocytes, including rapid cell-cycle exit, re-expression of differentiation markers and improved filtration barrier function. These data reveal an unexpected capacity of podocytes to reversibly enter the cell cycle, suggest that podocyte renewal may contribute to glomerular homeostasis and implicate the telomerase and Wnt-ß-catenin pathways in podocyte proliferation and disease.