TGF-beta 1-induced epithelial-to-mesenchymal transition and therapeutic intervention in diabetic nephropathy

Background/Aims: Epithelial-to-mesenchymal cell transformation (EMT) is the trans-differentiation of tubular epithelial cells into myofibroblasts, an event underlying progressive chronic kidney disease in diabetes, resulting in fibrosis. Mainly reported in proximal regions of the kidney, EMT is now recognized as a key contributor to the loss of renal function throughout the nephron in diabetic nephropathy (DN). Concomitant upregulation of TGF-beta in diabetes makes this pro-fibrotic cytokine an obvious candidate in the development of these fibrotic complications. This article reviews recent findings clarifying our understanding of the role of TGF-beta and associated sub-cellular proteins in EMT. Methods: To understand the pathology of EMT and the role of TGF-beta, we reviewed the literature using PubMed for English language articles that contained key words related to EMT, TGF-beta and DN. Results: EMT and phenotypic plasticity of epithelial cells throughout the nephron involves cytoskeletal reorganization and de novo acquisition of classic mesenchymal markers. Concurrent downregulation of epithelial adhesion molecules results in a loss of function and decreased cell coupling, contributing to a loss of epithelial integrity. TGF-beta 1 is pivotal in mediating these phenotypic changes. Conclusion: TGF-beta-induced EMT is a key contributor to fibrotic scar formation as seen in DN, and novel routes for future therapeutic intervention are discussed

SGK1 in the kidney: disrupted sodium transport in diabetes and beyond

Renal complications of diabetes can be severe; however, the mechanisms that underlie the development and progression of diabetic nephropathy are poorly understood. Recent evidence suggests that the serum and glucocorticoid induced kinase-1 (SGK1) may be key to this process. SGK1 expression and function are increased in models of diabetes and polymorphisms of the SGK1 gene are associated with type 2 diabetes mellitus. A key regulator of sodium transport within the renal epithelium of the distal nephron, SGK1 was originally isolated as a glucocorticoid-sensitive gene that regulated the epithelial sodium channel (ENaC; known also as the sodium channel, nonvoltage-gated 1, SCNN1). It is now apparent that SGK1 modulates sodium re-absorption by a number of sodium transporters/channels throughout the length of the nephron including; the Na+/H+ exchange isoform 3 (NHE3), the Na+Cl- co-transporter (NCC) and the Na+/K+-ATPase. In addition, SGK1 is regulated by a diverse range of factors including; insulin, glucose, intracellular calcium, transforming growth factor-beta1, flow rate and osmolality. This brief review examines the evidence supporting an involvement of SGK1 in diabetic nephropathy and discusses how dysregulated sodium transport may account for the development of secondary hypertension associated with the condition. Furthermore, the article examines how aberrant SGK1 expression and activity may be responsible for the cellular changes seen in the damaged nephron

Functional expression of TRPV4 channels in human collecting duct cells: implications for secondary hypertension in diabetic nephropathy

Background. The Vanilloid subfamily of transient receptor potential (TRPV) ion channels has been widely implicated in detecting osmotic and mechanical stress. In the current study, we examine the functional expression of TRPV4 channels in cell volume regulation in cells of the human collecting duct. Methods. Western blot analysis, siRNA knockdown, and microfluorimetry were used to assess the expression and function of TRPV4 in mediating Ca2+-dependent mechanical stimulation within a novel system of the human collecting duct (HCD). Results. Native and siRNA knockdown of TRPV4 protein expression was confirmed by western blot analysis. Touch was used as a cell-directed surrogate for osmotic stress. Mechanical stimulation of HCD cells evoked a transient increase in [Ca2+]i that was dependent upon thapsigargin-sensitive store release and Ca2+ influx. At 48 hrs, high glucose and mannitol (25 mM) reduced TRPV4 expression by 54% and 24%, respectively. Similar treatment doubled SGK1 expression. Touch-evoked changes were negated following TRPV4 knockdown. Conclusion. Our data confirm expression of Ca2+-dependent TRPV4 channels in HCD cells and suggest that a loss of expression in response to high glucose attenuates the ability of the collecting duct to exhibit regulatory volume decreases, an effect that may contribute to the pathology of fluid and electrolyte imbalance as observed in diabetic nephropathy

An adaptive grid algorithm for one-dimensional nonlinear equations

Richards' equation, which models the flow of liquid through unsaturated porous media, is highly nonlinear and difficult to solve. Step gradients in the field variables require the use of fine grids and small time step sizes. The numerical instabilities caused by the nonlinearities often require the use of iterative methods such as Picard or Newton interation. These difficulties result in large CPU requirements in solving Richards equation. With this in mind, adaptive and multigrid methods are investigated for use with nonlinear equations such as Richards' equation. Attention is focused on one-dimensional transient problems. To investigate the use of multigrid and adaptive grid methods, a series of problems are studied. First, a multigrid program is developed and used to solve an ordinary differential equation, demonstrating the efficiency with which low and high frequency errors are smoothed out. The multigrid algorithm and an adaptive grid algorithm is used to solve one-dimensional transient partial differential equations, such as the diffusive and convective-diffusion equations. The performance of these programs are compared to that of the Gauss-Seidel and tridiagonal methods. The adaptive and multigrid schemes outperformed the Gauss-Seidel algorithm, but were not as fast as the tridiagonal method. The adaptive grid scheme solved the problems slightly faster than the multigrid method. To solve nonlinear problems, Picard iterations are introduced into the adaptive grid and tridiagonal methods. Burgers' equation is used as a test problem for the two algorithms. Both methods obtain solutions of comparable accuracy for similar time increments. For the Burgers' equation, the adaptive grid method finds the solution approximately three times faster than the tridiagonal method. Finally, both schemes are used to solve the water content formulation of the Richards' equation. For this problem, the adaptive grid method obtains a more accurate solution in fewer work units and less computation time than required by the tridiagonal method. The performance of the adaptive grid method tends to degrade as the solution process proceeds in time, but still remains faster than the tridiagonal scheme

'Special K' and a loss of cell-to-cell adhesion in proximal tubule-derived epithelial cells: modulation of the adherens junction complex by ketamine

Ketamine, a mild hallucinogenic class C drug, is the fastest growing ‘party drug’ used by 16–24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24–48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1–1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and β-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFβ, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention

A multidisciplinary approach to the implementation of non-pharmacological strategies to manage infant pain

Hills E., Rosenberg J., Banfield N., Harding C. A multidisciplinary approach to the implementation of non-pharmacological strategies to manage infant pain. Infant 2020; 16(2): 78-81. 1. Newborn infants are capable of experiencing pain. 2. Infants requiring specialist hospital care are likely to experience painful medical procedures. 3. Unmanaged pain has a long-lasting impact on an infant’s behaviour and physiological status

Visfatin reduces gap junction mediated cell-to-cell communication in proximal tubule-derived epithelial cells

Background/Aims: In the current study we examined if the adipocytokine, visfatin, alters connexin-mediated intercellular communication in proximal tubule-derived epithelial cells. Methods: The effects of visfatin (10-200ng/mL) on cell viability and cytotoxicity in HK2-cells were assessed by MTT, crystal violet and lactate dehydrogenase assays. Western blot analysis was used to confirm expression of Cx26, Cx40 and Cx43. The effect of visfatin (10-200ng/mL) on TGF-β1 secretion was confirmed by ELISA, and the effects of both TGF-β1 (2-10ng/mL) and visfatin (10-200ng/mL) on connexin expression were assessed by western blot. Functional intercellular communication was determined using transfer of Lucifer Yellow and paired-whole cell patch clamp electrophysiology. Results: In low glucose (5mM), visfatin (10-200ng/mL) did not affect membrane integrity, cytotoxicity or cell viability at 48hrs, but did evoke a concentration-dependent reduction in Cx26 and Cx43 expression. The expression of Cx40 was unaffected. At 48hrs, visfatin (10-200ng/mL) increased the secretion of TGF-β1 and the visfatin-evoked changes in connexin expression were mimicked by exogenous application of the pro-fibrotic cytokine (2-10ng/ml). Visfatin reduced dye transfer between coupled cells and decreased functional conductance, with levels falling by 63% as compared to control. Although input resistance was increased following visfatin treatment by 166%, the change was not significant as compared to control. The effects of visfatin on Cx-expression and cell-coupling were blocked in the presence of a TGF-β1 specific neutralizing antibody. Conclusions: The adipocytokine visfatin selectively evoked a non-toxic reduction in connexin expression in HK2-cells. The loss in gap-junction associated proteins was mirrored by a loss in functional conductance between coupled cells. Visfatin increased TGF-β secretion and the pattern of change for connexins expression was mimicked by exogenous application of TGF-β1. The effect of visfatin on Cx-expression and dye transfer were negated in the presence of a TGF-β1 neutralising antibody. These data suggest that visfatin reduces connexin-mediated intercellular communication in proximal tubule-derived epithelial cells via a TGF-β dependent pathway. © 2013 S. Karger AG, Base

Calcium-sensing receptor activation increases cell-cell adhesion and ß-cell function

Background/Aims: The extracellular calcium-sensing receptor (CaR) is expressed in pancreatic β-cells where it is thought to facilitate cell-to-cell communication and augment insulin secretion. However, it is unknown how CaR activation improves β-cell function. Methods: Immunocytochemistry and western blotting confirmed the expression of CaR in MIN6 β-cell line. The calcimimetic R568 (1µM) was used to increase the affinity of the CaR and specifically activate the receptor at a physiologically appropriate extracellular calcium concentration. Incorporation of 5-bromo-2’-deoxyuridine (BrdU) was used to measure cell proliferation, whilst changes in non-nutrient-evoked cytosolic calcium were assessed using fura-2-microfluorimetry. AFM-single-cell-force spectroscopy related CaR-evoked changes in epithelial (E)-cadherin expression to improved functional tethering between coupled cells. Results: Activation of the CaR over 48hr doubled the expression of E-cadherin (206±41%) and increased L-type voltage-dependent calcium channel expression by 70% compared to control. These changes produced a 30% increase in cell-cell tethering and elevated the basal-to-peak amplitude of ATP (50µM) and tolbutamide (100µM)-evoked changes in cytosolic calcium. Activation of the receptor also increased PD98059 (1-100µM) and SU1498 (1-100µM)-dependent β-cell proliferation. Conclusion: Our data suggest that activation of the CaR increases E-cadherin mediated functional tethering between β-cells and increases expression of L-type VDCC and secretagogue-evoked changes in [Ca2+]i. These findings could explain how local changes in calcium, co-released with insulin, activate the CaR on neighbouring cells to help ensure efficient and appropriate secretory function

Characteristics, Career Paths, and Training Needs of Financial Aid Employees in the WASFAA Region

This article was re-written by the author from a presentation he made at the 1986 WASFAA Conference, and is based upon a survey of the WASFAA region financial aid offices taken in 1985. It shows wide variations in the demographic characteristics and backgrounds of student financial aid office employees, chiefly by job level

Emotional Exhaustion: Creation of a New Measure and Exploration of the Construct

Depression is an important mental health issue that affects many people each year. Understanding depression and its associated constructs is crucial to the prevention and treatment of this disorder. Until now, emotional exhaustion has been exclusively studied in the context of burnout and job satisfaction. The current study aims to bridge this gap in the literature by creating a new measure of emotional exhaustion that more broadly assesses the construct and relating it to other relevant measures. Emotional exhaustion has been shown to be related to depression in the context of burnout. The creation of the new measure of emotional exhaustion, the Emotional Exhaustion Questionnaire (EEQ), is described. The EEQ was administered to 200 adults through Amazon's MTurk service. The measure had excellent internal consistency and consisted of a single factor. Results supported the convergent validity of the EEQ as it was strongly and positively related to the traditional measure of emotional exhaustion used in burnout literature, the Maslach Burnout Inventory (MBI). The EEQ was also related in expected directions to a number of factors that have previously been associated with emotional exhaustion in the burnout literature including neuroticism, depression symptoms, effort-reward imbalance, and emotional dissonance. When added into a linear regression model predicting depression symptoms, the EEQ significantly improved upon a model including only the MBI, which suggests that the EEQ provides some incremental utility over the MBI. Exploratory analyses indicated that the EEQ was related to other relevant measures in expected ways including measures of suicidal ideation, distress tolerance, and non-suicidal self-injury. Overall, the EEQ is a brief, highly internally consistent measure of emotional exhaustion with good evidence for convergent validity. This provides good initial evidence to support future studies investigating the potential causal relationships between emotional exhaustion and psychopathology