Podocyte-Parietal Epithelial Cell Interdependence in Glomerular Development and Disease.

Podocytes and parietal epithelial cells (PECs) are among the few principal cell types within the kidney glomerulus, the former serving as a crucial constituent of the kidney filtration barrier and the latter representing a supporting epithelial layer that adorns the inner wall of Bowman's capsule. Podocytes and PECs share a circumscript developmental lineage that only begins to diverge during the S-shaped body stage of nephron formation-occurring immediately before the emergence of the fully mature nephron. These two cell types, therefore, share a highly conserved gene expression program, evidenced by recently discovered intermediate cell types occupying a distinct spatiotemporal gene expression zone between podocytes and PECs. In addition to their homeostatic functions, podocytes and PECs also have roles in kidney pathogenesis. Rapid podocyte loss in diseases, such as rapidly progressive GN and collapsing and cellular subtypes of FSGS, is closely allied with PEC proliferation and migration toward the capillary tuft, resulting in the formation of crescents and pseudocrescents. PECs are thought to contribute to disease progression and severity, and the interdependence between these two cell types during development and in various manifestations of kidney pathology is the primary focus of this review.

The Self-Determination Inventory: Student Report American Sign Language Translation.

Research literature and community narratives both emphasize the importance of self-determination in the lives of deaf youth. This paper describes the development, initial validation, and potential applications of a translated measure of self-determination for deaf youth, the SDI:SR ASL Translation (SDI:SR ASL). A sample of 3,309 young people who completed the SDI:SR, of whom 392 were deaf, was used in this validation study. Results provide preliminary support for the use of SDI:SR ASL with deaf youth. Findings also indicate that deaf youth who take the SDI:SR ASL score more similarly to youth without disabilities taking the SDI:SR than youth with disabilities. The SDI:SR ASL can be an important tool for researchers and practitioners to better understand self-determination among deaf youth and facilitate continued development of self-determination skills.

Cut-Score Operating Function Extensions: Penalty-Based Errors and Uncertainty in Standard Settings.

We model pass/fail examinations aiming to provide a systematic tool to minimize classification errors. We use the method of cut-score operating functions to generate specific cut-scores on the basis of minimizing several important misclassification measures. The goal of this research is to examine the combined effects of a known distribution of examinee abilities and uncertainty in the standard setting on the optimal choice of the cut-score. In addition, we describe an online application that allows others to utilize the cut-score operating function for their own standard settings.

Podocyte-specific KLF4 is required to maintain parietal epithelial cell quiescence in the kidney.

Podocyte loss triggering aberrant activation and proliferation of parietal epithelial cells (PECs) is a central pathogenic event in proliferative glomerulopathies. Podocyte-specific Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, is essential for maintaining podocyte homeostasis and PEC quiescence. Using mice with podocyte-specific knockdown of Klf4, we conducted glomerular RNA-sequencing, tandem mass spectrometry, and single-nucleus RNA-sequencing to identify cell-specific transcriptional changes that trigger PEC activation due to podocyte loss. Integration with in silico chromatin immunoprecipitation identified key ligand-receptor interactions, such as fibronectin 1 (FN1)­αVß6, between podocytes and PECs dependent on KLF4 and downstream signal transducer and activator of transcription 3 (STAT3) signaling. Knockdown of Itgb6 in PECs attenuated PEC activation. Additionally, podocyte-specific induction of human KLF4 or pharmacological inhibition of downstream STAT3 activation reduced FN1 and integrin ß 6 (ITGB6) expression and mitigated podocyte loss and PEC activation in mice. Targeting podocyte-PEC crosstalk might be a critical therapeutic strategy in proliferative glomerulopathies.

Targeting STAT3 signaling in kidney disease.

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is a multifaceted transduction system that regulates cellular responses to incoming signaling ligands. STAT3 is a central member of the JAK/STAT signaling cascade and has long been recognized for its increased transcriptional activity in cancers and autoimmune disorders but has only recently been in the spotlight for its role in the progression of kidney disease. Although genetic knockout and manipulation studies have demonstrated the salutary benefits of inhibiting STAT3 activity in several kidney disease models, pharmacological inhibition has yet to make it to the clinical forefront. In recent years, significant effort has been aimed at suppressing STAT3 activation for treatment of cancers, which has led to the development of a wide variety of STAT3 inhibitors, but only a handful have been tested in kidney disease models. Here, we review the detrimental role of dysregulated STAT3 activation in a variety of kidney diseases and the current progress in the treatment of kidney diseases with pharmacological inhibition of STAT3 activity.

Podocyte-Specific Induction of Krüppel-Like Factor 15 Restores Differentiation Markers and Attenuates Kidney Injury in Proteinuric Kidney Disease.

BACKGROUND: Podocyte injury is the hallmark of proteinuric kidney diseases, such as FSGS and minimal change disease, and destabilization of the podocyte's actin cytoskeleton contributes to podocyte dysfunction in many of these conditions. Although agents, such as glucocorticoids and cyclosporin, stabilize the actin cytoskeleton, systemic toxicity hinders chronic use. We previously showed that loss of the kidney-enriched zinc finger transcription factor Krüppel-like factor 15 (KLF15) increases susceptibility to proteinuric kidney disease and attenuates the salutary effects of retinoic acid and glucocorticoids in the podocyte. METHODS: We induced podocyte-specific KLF15 in two proteinuric murine models, HIV-1 transgenic (Tg26) mice and adriamycin (ADR)-induced nephropathy, and used RNA sequencing of isolated glomeruli and subsequent enrichment analysis to investigate pathways mediated by podocyte-specific KLF15 in Tg26 mice. We also explored in cultured human podocytes the potential mediating role of Wilms Tumor 1 (WT1), a transcription factor critical for podocyte differentiation. RESULTS: In Tg26 mice, inducing podocyte-specific KLF15 attenuated podocyte injury, glomerulosclerosis, tubulointerstitial fibrosis, and inflammation, while improving renal function and overall survival; it also attenuated podocyte injury in ADR-treated mice. Enrichment analysis of RNA sequencing from the Tg26 mouse model shows that KLF15 induction activates pathways involved in stabilization of actin cytoskeleton, focal adhesion, and podocyte differentiation. Transcription factor enrichment analysis, with further experimental validation, suggests that KLF15 activity is in part mediated by WT1. CONCLUSIONS: Inducing podocyte-specific KLF15 attenuates kidney injury by directly and indirectly upregulating genes critical for podocyte differentiation, suggesting that KLF15 induction might be a potential strategy for treating proteinuric kidney disease.

Krüppel-like factor 4 is a negative regulator of STAT3-induced glomerular epithelial cell proliferation.

Pathologic glomerular epithelial cell (GEC) hyperplasia is characteristic of both rapidly progressive glomerulonephritis (RPGN) and subtypes of focal segmental glomerulosclerosis (FSGS). Although initial podocyte injury resulting in activation of STAT3 signals GEC proliferation in both diseases, mechanisms regulating this are unknown. Here, we show that the loss of Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, enhances GEC proliferation in both RPGN and FSGS due to dysregulated STAT3 signaling. We observed that podocyte-specific knockdown of Klf4 (C57BL/6J) increased STAT3 signaling and exacerbated crescent formation after nephrotoxic serum treatment. Interestingly, podocyte-specific knockdown of Klf4 in the FVB/N background alone was sufficient to activate STAT3 signaling, resulting in FSGS with extracapillary proliferation, as well as renal failure and reduced survival. In cultured podocytes, loss of KLF4 resulted in STAT3 activation and cell-cycle reentry, leading to mitotic catastrophe. This triggered IL-6 release into the supernatant, which activated STAT3 signaling in parietal epithelial cells. Conversely, either restoration of KLF4 expression or inhibition of STAT3 signaling improved survival in KLF4-knockdown podocytes. Finally, human kidney biopsy specimens with RPGN exhibited reduced KLF4 expression with a concomitant increase in phospho-STAT3 expression as compared with controls. Collectively, these results suggest the essential role of KLF4/STAT3 signaling in podocyte injury and its regulation of aberrant GEC proliferation.

Growth Trajectory in Children With Short Bowel Syndrome During the First 2 Years of Life.

OBJECTIVES: Infants with short bowel syndrome (SBS) require diligent nutritional support for adequate growth. Enteral independence is a primary goal, but must be balanced with ensuring sufficient nutrition. We aimed to describe growth trajectory in infants with SBS as function of nutritional intake during first 2 years of life. METHODS: Infants with SBS were reviewed (2008-2016). z Scores for weight, height, and head circumference (HC) were recorded at birth, 3, 6, 12, 18, and 24 months. Nutritional intake, serum liver enzyme, and bilirubin levels were assessed at all time points. Pearson correlation coefficients were used to measure association with P < 0.05 considered significant. RESULTS: Forty-one infants were included, with median gestational age of 34 weeks (interquartile range [IQR] 29-36 weeks). Median small bowel length was 36 cm (IQR 26-52 cm) and median % expected small bowel length was 28% (IQR 20%-42%). Mean z scores for weight and length were >0 at birth, but <0 from 3 months to 2 years. HC remained <0 throughout the study. Mean z scores at 2 years for weight, length, HC, and weight-for-length were -0.90 (SD 1.1), -1.33 (SD 1.4), -0.67 (SD 1.2), and -0.12 (SD 1.2), respectively. Percentage calories from PN was positively correlated with weight in the first 3 months of life (P = 0.01). CONCLUSIONS: Babies with SBS are high risk for poor growth during the first 2 years of life. Although weaning PN is important for these patients, doing so too quickly in infancy may contribute to compromised growth. The long-term impact on overall development is not known.

The loss of Krüppel-like factor 15 in Foxd1+ stromal cells exacerbates kidney fibrosis.

Large epidemiological studies clearly demonstrate that multiple episodes of acute kidney injury contribute to the development and progression of kidney fibrosis. Although our understanding of kidney fibrosis has improved in the past two decades, we have limited therapeutic strategies to halt its progression. Myofibroblast differentiation and proliferation remain critical to the progression of kidney fibrosis. Although canonical Wnt signaling can trigger the activation of myofibroblasts in the kidney, mediators of Wnt inhibition in the resident progenitor cells are unclear. Recent studies demonstrate that the loss of a Krüppel-like factor 15 (KLF15), a kidney-enriched zinc-finger transcription factor, exacerbates kidney fibrosis in murine models. Here, we tested whether Klf15 mRNA and protein expression are reduced in late stages of fibrosis in mice that underwent unilateral ureteric obstruction, a model of progressive renal fibrosis. Knockdown of Klf15 in Foxd1-expressing cells (Foxd1-Cre Klf15fl/fl) increased extracellular matrix deposition and myofibroblast proliferation as compared to wildtype (Foxd1-Cre Klf15+/+) mice after three and seven days of ureteral obstruction. This was validated in mice receiving angiotensin II treatment for six weeks. In both these murine models, the increase in renal fibrosis was found in Foxd1-Cre Klf15fl/fl mice and accompanied by the activation of Wnt/ß-catenin signaling. Furthermore, knockdown of Klf15 in cultured mouse embryonic fibroblasts activated canonical Wnt/ß-catenin signaling, increased profibrotic transcripts, and increased proliferation after treatment with a Wnt1 ligand. Conversely, the overexpression of KLF15 inhibited phospho-ß-catenin (Ser552) expression in Wnt1-treated cells. Thus, KLF15 has a critical role in attenuating kidney fibrosis by inhibiting the canonical Wnt/ß-catenin pathway.

Growth in Prepubertal Children With Cystic Fibrosis Treated With Ivacaftor.

BACKGROUND AND OBJECTIVES: Cystic fibrosis (CF) is known for its impact on the lung and pancreas of individuals; however, impaired growth is also a common complication. We hypothesized that targeting the biological defect in the CF transmembrane conductance regulator (CFTR) protein may affect growth outcomes. METHODS: In this post hoc analysis, we assessed linear growth and weight in 83 children (aged 6-11 years) enrolled in 2 clinical trials, the longitudinal-observation GOAL study and the placebo-controlled ENVISION study, to evaluate the effects of ivacaftor, a CFTR potentiator. We calculated height and weight z scores and height and weight growth velocities (GVs). RESULTS: In ivacaftor-treated children in GOAL, height and weight z scores increased significantly from baseline to 6 months (increases of 0.1 [P < .05] and 0.26 [P < .0001], respectively); height GV increased significantly from 3 to 6 months (2.10-cm/year increase; P < .01). In ivacaftor-treated children in ENVISION, height and weight z scores increased significantly from baseline to 48 weeks (increases of 0.17 [P < .001] and 0.35 [P < .001], respectively). Height and weight GVs from baseline to 48 weeks were also significantly higher with ivacaftor than with placebo (differences of 1.08 cm/year [P < .05] and 3.11 kg/year [P < .001], respectively). CONCLUSIONS: Ivacaftor treatment in prepubescent children may help to address short stature and altered GV in children with CF; results from these analyses support the existence of an intrinsic defect in the growth of children with CF that may be ameliorated by CFTR modulation.

What Does the Shipley-2 Measure for Children and Adolescents? Integrated and Conjoint Confirmatory Factor Analysis With the WISC-IV.

We used integrated and conjoint confirmatory factor analysis of Shipley-2 and Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) data to investigate constructs measured in the Shipley-2 for children and adolescents. We also estimated Shipley-2 composite reliability at the subtest level rather than the item level. The three Shipley-2 subtests for the most part measured what was described in the manual, although Block Patterns measured visual spatial ability in addition to fluid ability and Abstraction was best considered a measure of psychometric g. The g factors derived from the WISC-IV and Shipley-2 were similar but not identical. Internal reliability estimates for Shipley-2 composites that were based on correlations between the subtests were substantially lower than those based on the items. Last, based on WISC-IV derived g factors, 37% to 53% of the variance in Shipley-2 composites was explained by g. Some of the reliable variance in the Shipley-2 composites was due to something specific that the subtests had in common not explained by psychometric g.

Evaluation and Comparison of Femoral Tunnel Placement During Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography: Effect of Notchplasty on Transtibial and Medial Portal Drilling.

BACKGROUND: Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure. HYPOTHESIS: Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling. STUDY DESIGN: Controlled laboratory study. METHODS: Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled in each knee according to group. A bamboo skewer was placed in the femoral tunnel, and the knees underwent a second CT scan. Arthroscopic notchplasty was performed, and the femoral tunnels were redrilled. Radiographs confirmed placement, and the post-notchplasty tunnel was reamed with a 4-mm reamer. The knees underwent a third CT scan. CT scans compared femoral tunnel placement with the native ACL footprint before and after notchplasty. RESULTS: The post-notchplasty transtibial group revealed an average of 68.3% coverage of the native ACL femoral origin. The medial portal group revealed an average of 60.8% coverage, with 1 instance of perforation of the posterior cortex. There were no instances of perforation in the transtibial group. CONCLUSION: Both drilling techniques place the graft in an anatomically correct position. CLINICAL RELEVANCE: Transtibial drilling of the femur can adequately place the entry tunnel at the origin of the ACL's native footprint.