Sweet, bloody consumption - what we eat and how it affects vascular ageing, the BBB and kidney health in CKD.

In today's industrialized society food consumption has changed immensely toward heightened red meat intake and use of artificial sweeteners instead of grains and vegetables or sugar, respectively. These dietary changes affect public health in general through an increased incidence of metabolic diseases like diabetes and obesity, with a further elevated risk for cardiorenal complications. Research shows that high red meat intake and artificial sweeteners ingestion can alter the microbial composition and further intestinal wall barrier permeability allowing increased transmission of uremic toxins like p-cresyl sulfate, indoxyl sulfate, trimethylamine n-oxide and phenylacetylglutamine into the blood stream causing an array of pathophysiological effects especially as a strain on the kidneys, since they are responsible for clearing out the toxins. In this review, we address how the burden of the Western diet affects the gut microbiome in altering the microbial composition and increasing the gut permeability for uremic toxins and the detrimental effects thereof on early vascular aging, the kidney per se and the blood-brain barrier, in addition to the potential implications for dietary changes/interventions to preserve the health issues related to chronic diseases in future.

Development and validation of the physician self-efficacy to manage emotional challenges Scale (PSMEC).

BACKGROUND: Medical students experience emotional challenges during their undergraduate education, often related to work-based learning. Consequently, they may experience feelings of uncertainty and self-doubt, which can negatively affect their well-being. Therefore, it is crucial to support students' development of their ability to manage distressful situations. Self-efficacy beliefs may be a central aspect of supporting them in this development, and have been shown to relate to resilient factors such as students' motivation, learning, and well-being. METHODS: We constructed a scale to measure medical students' physician self-efficacy to manage emotional challenges during work-based learning, the PSMEC scale. The aim of the present study was to evaluate some of the psychometric properties of the PSMEC scale. The scale consists of 17 items covering five subscales: (1) medical knowledge and competence, (2) communication with difficult patients and delivering bad news, (3) being questioned and challenged, (4) educative competence in patient encounters, and (5) ability to establish and maintain relationships with healthcare professionals. Data were collected from 655 medical students from all seven medical schools in Sweden. To investigate the scale's dimensionality and measurement invariance with regard to gender and time in education, single and multiple group confirmatory factor models were estimated using techniques suitable for ordered categorical data. Measures of Cronbach's alpha were calculated to evaluate internal consistency. RESULTS: The scale showed good internal consistency on both the global dimension and the five subdimensions of self-efficacy. In addition, the scale was shown to be measurement invariant across genders and times in education, indicating that the scale means of male and female medical students and the scale means of students at the middle and end of their education can be compared. CONCLUSIONS: The physician self-efficacy to manage emotional challenges scale demonstrated satisfactory psychometric properties, with regards to dimensionality, internal consistency, and measurement invariance relating to gender and time in education, and this study supports the usefulness of this scale when measuring self-efficacy in relation to emotional challenges.

Intranasal Administration of Sugarcane Ash Causes Chronic Kidney Disease in Rats.

Background. Silica nanoparticles found in sugarcane ash have been postulated to be a toxicant contributing to chronic kidney disease of unknown etiology (CKDu). However, while the administration of manufactured silica nanoparticles is known to cause chronic tubulointerstitial disease in rats, the effect of administering sugarcane ash on kidney pathology remains unknown. Here we investigate whether sugarcane ash can induce CKD in rats. Methods. Sugarcane ash was administered for 13 weeks into the nares of rats (5 mg/day for 5d/week), and blood, urine and kidney tissues were collected at 13 weeks (at the end of ash administration) and in a separate group of rats at 24 weeks (11 weeks after stopping ash administration). Kidney histology was evaluated, and inflammation and fibrosis (collagen deposition) measured. Results. Sugarcane ash exposure led to the accumulation of silica in the kidneys, lungs, liver and spleen of rats. Mild proteinuria developed although renal function was largely maintained. However, biopsies showed focal glomeruli with segmental glomerulosclerosis, and tubulointerstitial inflammation and fibrosis that tended to worsen even after the ash administration had been stopped. Staining for the lysosomal marker, LAMP-1, showed decreased staining in ash administered rats consistent with lysosomal activation. Conclusion. Sugarcane ash containing silica nanoparticles can cause CKD in rats.

Clinical findings and kidney morphology in chronic kidney disease of unknown cause in India.

BACKGROUND: Chronic kidney disease of unknown cause (CKDu) is an emerging health problem in India and other countries worldwide. However, clinical descriptions, including kidney pathology, are scarce. METHODS: This is a descriptive case series of patients with CKDu from an endemic region in India, with a focus on clinical and biochemical characteristics, kidney biopsy findings, and environmental exposure. Patients with suspected CKDu, aged 20-65, and eGFR 30-80 mL/min/1.73 m2 from rural areas with endemic prevalence of CKDu were included. The exclusion criteria were diabetes mellitus, uncontrolled hypertension, proteinuria >1 g/24 h, or other known kidney diseases. The participants underwent kidney biopsies, and blood and urine samples were collected. RESULTS: Fourteen participants (3 females, 11 males) with a mean eGFR of 53 (range 29-78) mL/min/1.73 m2 were included. Kidney biopsies showed a combination of chronic tubulointerstitial damage, glomerulosclerosis, and glomerular hypertrophy, with varying degrees of interstitial inflammation. Eight participants had polyuria (diuresis ≥ 3 L/day). The urinary sediments were bland, with no haematuria. Serum potassium and sodium levels were, in most cases, normal but within the lower reference interval. CONCLUSION: The kidney morphology and clinical characteristics in patients with CKDu in India were similar to those described for CKDu in Central America and Sri Lanka.

The impact of emotionally challenging situations on medical students' professional identity formation.

In their interactions with patients and health care professionals during work-based learning, medical students are known to experience emotionally challenging situations that can evoke negative feelings. Students have to manage these emotions. Students learn and develop their professional identity formation through interactions with patients and members of the healthcare teams. Earlier studies have highlighted the issues involved with processing emotionally challenging situations, although studies concerning learning and professional identity formation in response to these experiences are rare. In this study, we explored medical students' experiences of emotionally challenging situations in work-based learning, and the impact these experiences had on forming medical students' professional identities. We conducted an analysis of narrative data (n = 85), using a constructivist grounded theory approach. The narratives were made up of medical students' reflective essays at the end of their education (tenth term). The analysis showed that students' main concern when facing emotionally challenging situations during their work-based education was the struggle to achieve and maintain a professional approach. They reported different strategies for managing their feelings and how these strategies led to diverse consequences. In the process, students also described arriving at insights into their own personal needs and shortcomings. We consider this development of self-awareness and resulting self-knowledge to be an important part of the continuously ongoing socialization process of forming a professional identity. Thus, experiencing emotionally challenging situations can be considered a unique and invaluable opportunity, as well as a catalyst for students' development. We believe that highlighting the impact of emotions in medical education can constitute an important contribution to knowledge about the process of professional identity formation. This knowledge can enable faculty to provide students with more effective and sufficient support, facilitating their journey in becoming physicians.

Renal mitochondrial dysfunction in ovine experimental sepsis-associated acute kidney injury.

Sheep develop sepsis-associated acute kidney injury (SA-AKI) during experimental sepsis despite normal to increased renal oxygen delivery. A disturbed relation between oxygen consumption (V̇o2) and renal Na+ transport has been demonstrated in sheep and in clinical studies of AKI, which could be explained by mitochondrial dysfunction. We investigated the function of isolated renal mitochondria compared with renal oxygen handling in an ovine hyperdynamic model of SA-AKI. Anesthetized sheep were randomized to either an infusion of live Escherichia coli with resuscitative measures (sepsis group; n = 13 animals) or served as controls (n = 8 animals) for 28 h. Renal V̇o2 and Na+ transport were repeatedly measured. Live cortical mitochondria were isolated at baseline and at the end of the experiment and assessed in vitro with high-resolution respirometry. Sepsis markedly reduced creatinine clearance, and the relation between Na+ transport and renal V̇o2 was decreased in septic sheep compared with control sheep. Cortical mitochondrial function was altered in septic sheep with a reduced respiratory control ratio (6.0 ± 1.5 vs. 8.2 ± 1.6, P = 0.006) and increased complex II-to-complex I ratio during state 3 (1.6 ± 0.2 vs. 1.3 ± 0.1, P = 0.0014) mainly due to decreased complex I-dependent state 3 respiration (P = 0.016). However, no differences in renal mitochondrial efficiency or mitochondrial uncoupling were found. In conclusion, renal mitochondrial dysfunction composed of a reduction of the respiratory control ratio and an increased complex II/complex I relation in state 3 was demonstrated in an ovine model of SA-AKI. However, the disturbed relation between renal V̇o2 and renal Na+ transport could not be explained by a change in renal cortical mitochondrial efficiency or uncoupling.NEW & NOTEWORTHY We studied the function of renal cortical mitochondria in relation to oxygen consumption in an ovine model of sepsis with acute kidney injury. We demonstrated changes in the electron transport chain induced by sepsis consisting of a reduced respiratory control ratio mainly by a reduced complex I-mediated respiration. Neither an increase in mitochondrial uncoupling nor a reduction in mitochondrial efficiency was demonstrated and cannot explain why oxygen consumption was unaffected despite reduced tubular transport.

Deep learning-based segmentation and quantification of podocyte foot process morphology suggests differential patterns of foot process effacement across kidney pathologies.

Morphological alterations at the kidney filtration barrier increase intrinsic capillary wall permeability resulting in albuminuria. However, automated, quantitative assessment of these morphological changes has not been possible with electron or light microscopy. Here we present a deep learning-based approach for segmentation and quantitative analysis of foot processes in images acquired with confocal and super-resolution fluorescence microscopy. Our method, Automatic Morphological Analysis of Podocytes (AMAP), accurately segments podocyte foot processes and quantifies their morphology. AMAP applied to a set of kidney diseases in patient biopsies and a mouse model of focal segmental glomerulosclerosis allowed for accurate and comprehensive quantification of various morphometric features. With the use of AMAP, detailed morphology of podocyte foot process effacement was found to differ between categories of kidney pathologies, showed detailed variability between diverse patients with the same clinical diagnosis, and correlated with levels of proteinuria. AMAP could potentially complement other readouts such as various omics, standard histologic/electron microscopy and blood/urine assays for future personalized diagnosis and treatment of kidney disease. Thus, our novel finding could have implications to afford an understanding of early phases of kidney disease progression and may provide supplemental information in precision diagnostics.

The role of dendrin in IgA nephropathy.

BACKGROUND: Immunoglobulin A nephropathy (IgAN) and its systemic variant IgA vasculitis (IgAV) damage the glomeruli, resulting in proteinuria, hematuria and kidney impairment. Dendrin is a podocyte-specific protein suggested to be involved in the pathogenesis of IgAN. Upon cell injury, dendrin translocates from the slit diaphragm to the nucleus, where it is suggested to induce apoptosis and cytoskeletal changes, resulting in proteinuria and accelerated disease progression in mice. Here we investigated gene and protein expression of dendrin in relation to clinical and histopathological findings to further elucidate its role in IgAN/IgAV. METHODS: Glomerular gene expression was measured using microarray on 30 IgAN/IgAV patients, 5 patients with membranous nephropathy (MN) and 20 deceased kidney donors. Dendrin was spatially evaluated on kidney tissue sections by immunofluorescence (IF) staining (IgAN patients, n = 4; nephrectomized kidneys, n = 3) and semi-quantified by immunogold electron microscopy (IgAN/IgAV patients, n = 21; MN, n = 5; living kidney donors, n = 6). Histopathological grading was performed according to the Oxford and Banff classifications. Clinical data were collected at the time of biopsy and follow-up. RESULTS: Dendrin mRNA levels were higher (P = .01) in IgAN patients compared with MN patients and controls and most prominently in patients with preserved kidney function and fewer chronic histopathological changes. Whereas IF staining did not differ between groups, immunoelectron microscopy revealed that a higher relative nuclear dendrin concentration in IgAN patients was associated with a slower annual progression rate and milder histopathological changes. CONCLUSION: Dendrin messenger RNA levels and relative nuclear protein concentrations are increased and associated with a more benign phenotype and progression in IgAN/IgAV patients.

Inhaled silica nanoparticles cause chronic kidney disease in rats.

Silica nanoparticles (SiNPs) released during the burning of sugarcane have been postulated to have a role in chronic kidney disease of unknown etiology. We tested the hypothesis that pristine SiNPs of the size present in sugarcane might cause chronic kidney injury when administered through the lung in rats. We administered 200- or 300-nm amorphous SiNPs twice weekly (4 mg/dose), or vehicle by oropharyngeal aspiration for 13 wk to rats followed by euthanasia after an additional 13 wk (26 wk total). Tissues were evaluated for the presence of SiNPs and evidence of histological injury. Both sizes of SiNPs caused kidney damage, with early tubular injury and inflammation (at week 13) that continued to inflammation and chronic fibrosis at week 26 despite discontinuation of the SiNP administration. Both sizes of SiNPs caused local inflammation in the lung and kidney and were detected in the serum and urine at week 13, and the 200-nm particles were also localized to the kidney with no evidence of retention of the 300-nm particles. At week 26, there was some clearance of the 200-nm silica from the kidneys, and urinary levels of SiNPs were reduced but still significant in both 200- and 300 nm-exposed rats. In conclusion, inhaled SiNPs cause chronic kidney injury that progresses despite stopping the SiNP administration. These findings support the hypothesis that human exposure to amorphous silica nanoparticles found in burned sugarcane fields could have a participatory role in chronic kidney disease of unknown etiology.NEW & NOTEWORTHY Inhalation of silica nanoparticles (SiNPs) released during the burning of sugarcane has been postulated to have a role in chronic kidney disease of unknown etiology (CKDu). We administered 200- and 300-nm amorphous SiNPs to rats by aspiration and observed kidney damage with tubular injury and inflammation that persisted even after stopping the SiNP exposure. These findings support the hypothesis that human exposure to SiNPs found in sugarcane ash could have a participatory role CKDu.

Fibroblast growth factor 23 is independently associated with renal magnesium handling in patients with chronic kidney disease.

Background: Disturbances in magnesium homeostasis are common in patients with chronic kidney disease (CKD) and are associated with increased mortality. The kidney is a key organ in maintaining normal serum magnesium concentrations. To this end, fractional excretion of magnesium (FEMg) increases as renal function declines. Despite recent progress, the hormonal regulation of renal magnesium handling is incompletely understood. Fibroblast Growth Factor 23 (FGF23) is a phosphaturic hormone that has been linked to renal magnesium handling. However, it has not yet been reported whether FGF23 is associated with renal magnesium handling in CKD patients. Methods: The associations between plasma FGF23 levels, plasma and urine magnesium concentrations and FEMg was investigated in a cross-sectional cohort of 198 non-dialysis CKD patients undergoing renal biopsy. Results: FGF23 was significantly correlated with FEMg (Pearson's correlation coefficient = 0.37, p<0.001) and urinary magnesium (-0.14, p=0.04), but not with plasma magnesium. The association between FGF23 and FEMg remained significant after adjusting for potential confounders, including estimated glomerular filtration rate (eGFR), parathyroid hormone and 25-hydroxyvitamin D. Conclusions: We report that plasma FGF23 is independently associated with measures of renal magnesium handling in a cohort of non-dialysis CKD patients. A potential causal relationship should be investigated in future studies.

Retinoic acid receptor responder1 promotes development of glomerular diseases via the Nuclear Factor-κB signaling pathway.

Inflammatory pathways are activated in most glomerular diseases but molecular mechanisms driving them in kidney tissue are poorly known. We identified retinoic acid receptor responder 1 (Rarres1) as a highly podocyte-enriched protein in healthy kidneys. Studies in podocyte-specific knockout animals indicated that Rarres1 was not needed for the normal development or maintenance of the glomerulus filtration barrier and did not modulate the outcome of kidney disease in a model of glomerulonephritis. Interestingly, we detected an induction of Rarres1 expression in glomerular and peritubular capillary endothelial cells in IgA and diabetic kidney disease, as well as in ANCA-associated vasculitis. Analysis of publicly available RNA data sets showed that the induction of Rarres1 expression was a common molecular mechanism in chronic kidney diseases. A conditional knock-in mouse line, overexpressing Rarres1 specifically in endothelial cells, did not show any obvious kidney phenotype. However, the overexpression promoted the progression of kidney damage in a model of glomerulonephritis. In line with this, conditional knock-out mice, lacking Rarres1 in endothelial cells, were partially protected in the disease model. Mechanistically, Rarres1 promoted inflammation and fibrosis via transcription factor Nuclear Factor-κB signaling pathway by activating receptor tyrosine kinase Axl. Thus, induction of Rarres1 expression in endothelial cells is a prevalent molecular mechanism in human glomerulopathies and this seems to have a pathogenic role in driving inflammation and fibrosis via the Nuclear Factor-κB signaling pathway.

Single-cell RNA sequencing reveals the mesangial identity and species diversity of glomerular cell transcriptomes.

Molecular characterization of the individual cell types in human kidney as well as model organisms are critical in defining organ function and understanding translational aspects of biomedical research. Previous studies have uncovered gene expression profiles of several kidney glomerular cell types, however, important cells, including mesangial (MCs) and glomerular parietal epithelial cells (PECs), are missing or incompletely described, and a systematic comparison between mouse and human kidney is lacking. To this end, we use Smart-seq2 to profile 4332 individual glomerulus-associated cells isolated from human living donor renal biopsies and mouse kidney. The analysis reveals genetic programs for all four glomerular cell types (podocytes, glomerular endothelial cells, MCs and PECs) as well as rare glomerulus-associated macula densa cells. Importantly, we detect heterogeneity in glomerulus-associated Pdgfrb-expressing cells, including bona fide intraglomerular MCs with the functionally active phagocytic molecular machinery, as well as a unique mural cell type located in the central stalk region of the glomerulus tuft. Furthermore, we observe remarkable species differences in the individual gene expression profiles of defined glomerular cell types that highlight translational challenges in the field and provide a guide to design translational studies.

A fast and simple clearing and swelling protocol for 3D in-situ imaging of the kidney across scales.

In recent years, many light-microscopy protocols have been published for visualization of nanoscale structures in the kidney. These protocols present researchers with new tools to evaluate both foot process anatomy and effacement, as well as protein distributions in foot processes, the slit diaphragm and in the glomerular basement membrane. However, these protocols either involve the application of different complicated super resolution microscopes or lengthy sample preparation protocols. Here, we present a fast and simple, five-hour long procedure for three-dimensional visualization of kidney morphology on all length scales. The protocol combines optical clearing and tissue expansion concepts to produce a mild swelling, sufficient for resolving nanoscale structures using a conventional confocal microscope. We show that the protocol can be applied to visualize a wide variety of pathologic features in both mouse and human kidneys. Thus, our fast and simple protocol can be beneficial for conventional microscopic evaluation of kidney tissue integrity both in research and possibly in future clinical routines.

Novel insights into the disease transcriptome of human diabetic glomeruli and tubulointerstitium.

BACKGROUND: Diabetic nephropathy (DN) is the most common cause of end-stage renal disease, affecting ∼30% of the rapidly growing diabetic population, and strongly associated with cardiovascular risk. Despite this, the molecular mechanisms of disease remain unknown. METHODS: RNA sequencing (RNAseq) was performed on paired, micro-dissected glomerular and tubulointerstitial tissue from patients diagnosed with DN [n = 19, 15 males, median (range) age: 61 (30-85) years, chronic kidney disease stages 1-4] and living kidney donors [n = 20, 12 males, median (range) age: 56 (30-70) years]. RESULTS: Principal component analysis showed a clear separation between glomeruli and tubulointerstitium transcriptomes. Differential expression analysis identified 1550 and 4530 differentially expressed genes, respectively (adjusted P < 0.01). Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses highlighted activation of inflammation and extracellular matrix (ECM) organization pathways in glomeruli, and immune and apoptosis pathways in tubulointerstitium of DN patients. Specific gene modules were associated with renal function in weighted gene co-expression network analysis. Increased messengerRNA (mRNA) expression of renal damage markers lipocalin 2 (LCN) and hepatitis A virus cellular receptor1 (HAVCR1) in the tubulointerstitial fraction was observed alongside higher urinary concentrations of the corresponding proteins neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in DN patients. CONCLUSIONS: Here we present the first RNAseq experiment performed on paired glomerular and tubulointerstitial samples from DN patients. We show that prominent disease-specific changes occur in both compartments, including relevant cellular processes such as reorganization of ECM and inflammation (glomeruli) as well as apoptosis (tubulointerstitium). The results emphasize the potential of utilizing high-throughput transcriptomics to decipher disease pathways and treatment targets in this high-risk patient population.

Can empathy be preserved in medical education?

OBJECTIVES: The aim of this study was to investigate changes in empathy during medical education, as well as to identify promoters and inhibitors of empathy and analyse their roles. METHODS: We used qualitative content analysis to examine 69 critically reflective essays written by medical students as a part of their final examination at the end of the medical program. The essays were based on previous self-evaluations performed each term and represented retrospective reflections on their professional development. RESULTS: A majority of the students felt that their empathy did not decrease during medical education. On the contrary, many felt that their empathy had increased, especially the cognitive part of empathy, without loss of affective empathy. Many of them described a professionalisation process resulting in an ability to meet patients with preserved empathy but without being overwhelmed by emotions. They identified several factors that promoted the development of empathy: a multiplicity of patients, positive role models, and educational activities focusing on reflection and self-awareness. They also identified inhibitors of empathy: lack of professional competence and a stressful and empathy-hostile medical culture. CONCLUSIONS: Our analysis of these retrospective reflections by students suggests that empathy can be preserved during medical education, despite the presence of important inhibitors of empathy. This finding might be due to the presence of more potent promoters and/or to the fact that educational activities might result in a decreased susceptibility to empathy-decreasing circumstances.

The kidney injury caused by the onset of acute graft-versus-host disease is associated with down-regulation of αKlotho.

Acute graft-versus-host disease (aGVHD) and kidney injury are the major complications after allogeneic hematopoietic stem cell transplantation (HSCT). Although the underlying mechanisms for the development of these complications are not yet fully understood, it has been proposed that emergence of aGVHD contributes to the development of kidney injury after HSCT. We have shown previously that aGVHD targets the kidney in a biphasic manner: at the onset, inflammatory genes are up-regulated, while when aGVHD becomes established, donor lymphocytes infiltrate the kidney. Here, we characterize renal manifestations at the onset of aGVHD. Mice receiving allogeneic bone marrow and spleen cells displayed symptoms of aGVHD and elevated serum levels of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) within 4 days. There was concurrent kidney injury with the following characteristics: (1) elevated expression of the kidney injury biomarker, neutrophil gelatinase-associated lipocalin (NGAL), (2) accumulation of hetero-lysosomes in proximal tubule epithelial cells, and (3) reductions in αKlotho mRNA and protein and increased serum levels of fibroblast growth factor 23 (Fgf23), phosphate and urea. This situation resembled acute renal injury caused by bacterial lipopolysaccharide. We conclude that the onset of aGVHD is associated with kidney injury involving down-regulation of αKlotho, a sight that may inspire novel therapeutic approaches.

Tissue immune profiles supporting response to mesenchymal stromal cell therapy in acute graft-versus-host disease-a gut feeling.

Acute graft-versus-host disease (aGvHD), post-allogeneic hematopoietic stem cell transplantation, is associated with high mortality rates in patients not responding to standard line care with steroids. Adoptive mesenchymal stromal cell (MSC) therapy has been established in some countries as a second-line treatment.Limitations in our understanding as to MSC mode of action and what segregates patient responders from non-responders to MSC therapy remain. The principal aim of this study was to evaluate the immune cell profile in gut biopsies of patients diagnosed with aGvHD and establish differences in baseline cellular composition between responders and non-responders to subsequent MSC therapy.Our findings indicate that a pro-inflammatory immune profile within the gut at the point of MSC treatment may impede their therapeutic potential. These findings support the need for further validation in a larger cohort of patients and the development of improved biomarkers in predicting responsiveness to MSC therapy.