| 1. |
- Sotak, Matus, et al.
(författare)
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Intestinal sodium/glucose cotransporter 3 expression is epithelial and downregulated in obesity.
- 2021
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Ingår i: Life sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to determine whether the sodium/glucose cotransporter family member SGLT3, a proposed glucose sensor, is expressed in the intestine and/or kidney, and if its expression is altered in mouse models of obesity and in humans before and after weight-loss surgery.We used in-situ hybridization and quantitative PCR to determine whether the Sglt3 isoforms 3a and 3b were expressed in the intestine and kidney of C57, leptin-deficient ob/ob, and diabetic BTBR ob/ob mice. Western blotting and immunohistochemistry were also used to assess SGLT3 protein levels in jejunal biopsies from obese patients before and after weight-loss Roux-en-Y gastric bypass surgery (RYGB), and in lean healthy controls.Sglt3a/3b mRNA was detected in the small intestine (duodenum, jejunum and ileum), but not in the large intestine or kidneys of mice. Both isoforms were detected in epithelial cells (confirmed using intestinal organoids). Expression of Sglt3a/3b mRNA in duodenum and jejunum was significantly lower in ob/ob and BTBR ob/ob mice than in normal-weight littermates. Jejunal SGLT3 protein levels in aged obese patients before Roux-en-Y gastric bypass (RYGB) were lower than in lean individuals, but substantially upregulated 6months post-RYGB.Our study shows that Sglt3a/3b is expressed primarily in epithelial cells of the small intestine in mice. Furthermore, we observed an association between intestinal mRNA Sglt3a/3b expression and obesity in mice, and between jejunal SGLT3 protein levels and obesity in humans. Further studies are required to determine the possible role of SGLT3 in obesity.
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| 2. |
- Lindskog, Annika, 1982, et al.
(författare)
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Melanocortin 1 receptor agonists reduce proteinuria.
- 2010
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Ingår i: Journal of the American Society of Nephrology : JASN. - 1533-3450 .- 1046-6673. ; 21:8, s. 1290-8
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Tidskriftsartikel (refereegranskat)abstract
- Membranous nephropathy is one of the most common causes of nephrotic syndrome in adults. Recent reports suggest that treatment with adrenocorticotropic hormone (ACTH) reduces proteinuria, but the mechanism of action is unknown. Here, we identified gene expression of the melanocortin receptor MC1R in podocytes, glomerular endothelial cells, mesangial cells, and tubular epithelial cells. Podocytes expressed most MC1R protein, which colocalized with synaptopodin but not with an endothelial-specific lectin. We treated rats with passive Heymann nephritis (PHN) with MS05, a specific MC1R agonist, which significantly reduced proteinuria compared with untreated PHN rats (P < 0.01). Furthermore, treatment with MC1R agonists improved podocyte morphology and reduced oxidative stress. In summary, podocytes express MC1R, and MC1R agonism reduces proteinuria, improves glomerular morphology, and reduces oxidative stress in nephrotic rats with PHN. These data may explain the proteinuria-reducing effects of ACTH observed in patients with membranous nephropathy, and MC1R agonists may provide a new therapeutic option for these patients.
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| 3. |
- Björnson Granqvist, Anna, 1974
(författare)
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Functional and molecular aspects of the glomerular barrier
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The kidneys are crucial for maintaining a normal salt-water balance in the body, which is a prerequisite for life. They do that by filtering 180 liters of plasma per day across the highly permselective glomerular barrier and reabsorbing 99 % of the filtrate. Proteinuria is a hallmark of renal disease and reflects damage to one or more of the components of the barrier, namely fenestrated endothelial cells, basement membrane, and podocytes. For several years, the basement membrane was considered to be the main barrier. Recently, research has focused on the podocytes, while the endothelium has received much less attention. The glomerular endothelial cells are covered however by a thick negatively charged cell surface coat, a glycocalyx, which most likely has selective properties. The glycocalyx is composed of plasma proteins, glycoproteins and proteoglycans. Proteoglycans (PG) are negatively charged molecules with a protein-core to which glycosaminoglycan (GAG) chains are attached. In this thesis, we have made a detailed analysis of the biosynthesis of PG and GAG by human and bovine glomerular endothelial cells, by human podocytes and by rat glomeruli in vivo. These cells were shown to express the following core proteins: syndecan, glypican, versican, perlecan, biglycan and decorin. When treating the cells with puromycin amino nucleoside (PAN), a drug known to induce nephrotic syndrome, we could see dramatic down-regulation of PGs, mainly versican, and of enzymes involved in the synthesis and modification of the glycosaminoglycan chains. Indeed, when analyzing the cell media after PAN treatment, a significant decrease in the amount of sulfate groups and the chain length was detected. These effects of PAN on glomerular cells were confirmed in a study on rats, in which molecular and physiological measurements were used to study the course of proteinuria for seven days. In these animals, PAN decreased the expression of nephrin, podocin and VEGF as well as with certain PGs and GAG enzymes. The marked changes of PG and GAG induced by PAN are likely to reduce both size and charge selectivity of the glomerular barrier.
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| 4. |
- Björnson Granqvist, Anna, 1974, et al.
(författare)
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Impaired glomerular and tubular antioxidative defense mechanisms in nephrotic syndrome.
- 2010
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Ingår i: American journal of physiology. Renal physiology. - : American Physiological Society. - 1522-1466 .- 1931-857X. ; 299:4
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Tidskriftsartikel (refereegranskat)abstract
- The molecular mechanisms behind acquired nephrotic syndrome (NS) are still largely unknown. One possible explanation for the development of proteinuria is oxidative damage to the glomerular cells. Our hypothesis was that the oxidative defense is weakened in NS, and we focused on measurements of the oxidative-antioxidative status in the glomerular and tubular parts of the nephron. Gene expression was analyzed in renal biopsies from patients with NS. In addition, to compare the acute and chronic phases of the disease, we studied puromycin-treated rats. In the biopsy material, the expression of enzymes involved in the antioxidative defense was higher in the tubulointerstitial compartment than in the glomerular cells. Real-time PCR analysis revealed a decreased glomerular expression in nephrotic kidneys for the antioxidant enzymes catalase and glutathione peroxidase-3, and -4. The tubular gene expression was downregulated for catalase, glutathione peroxidase-3, and thioredoxin reductase-1 and -2. The altered gene expression was accompanied by increased lipid peroxidation in urine. In rats, serum concentrations of ascorbyl-free radicals, measured with electron spin resonance, were elevated in the acute phase of the disease, suggesting increased oxidative stress in the circulation. In addition, we saw an increase in the plasma antioxidant capacity combined with a decreased oxidation of proteins in sera from nephrotic rats, but not from humans. In conclusion, there is a marked downregulation of several antioxidative enzymes in nephrotic kidneys, especially in glomerular structures. Our data suggest that oxidative damage to glomerular cells may contribute significantly to the course and prognosis of nephrotic syndrome.
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| 5. |
- Ebefors, Kerstin, 1977, et al.
(författare)
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Role of glomerular proteoglycans in IgA nephropathy
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:4
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Tidskriftsartikel (refereegranskat)abstract
- Mesangial matrix expansion is a prominent feature of the most common form of glomerulonephritis, IgA nephropathy (IgAN). To find molecular markers and improve the understanding of the disease, the gene and protein expression of proteoglycans were investigated in biopsies from IgAN patients and correlated to clinical and morphological data. We collected and microdissected renal biopsies from IgAN patients (n = 19) and from healthy kidney donors (n = 14). Patients were followed for an average time of 4 years and blood pressure was according to target guidelines. Distinct patterns of gene expression were seen in glomerular and tubulo-interstitial cells. Three of the proteoglycans investigated were found to be of special interest and upregulated in glomeruli: perlecan, decorin and biglycan. Perlecan gene expression negatively correlated to albumin excretion and progress of the disease. Abundant decorin protein expression was found in sclerotic glomeruli, but not in unaffected glomeruli from IgAN patients or in controls. Transforming growth factor beta (TGF-beta), known to interact with perlecan, decorin and biglycan, were upregulated both on gene and protein level in the glomeruli. This study provides further insight into the molecular mechanisms involved in mesangial matrix expansion in IgAN. We conclude that perlecan is a possible prognostic marker for patients with IgAN. In addition, the up-regulation of biglycan and decorin, as well as TGF-beta itself, indicate that regulation of TGF-beta, and other profibrotic markers plays a role in IgAN pathology.
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| 6. |
- Elvin, Johannes, et al.
(författare)
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Melanocortin 1 Receptor Agonist Protects Podocytes Through Catalase and RhoA Activation.
- 2016
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Ingår i: American journal of physiology. Renal physiology. - : American Physiological Society. - 1522-1466 .- 1931-857X. ; 310:9
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Tidskriftsartikel (refereegranskat)abstract
- Drugs containing adrenocorticotropic hormone (ACTH) have been used as therapy for patients with nephrotic syndrome. We have previously shown that ACTH and a selective agonist for the melanocortin 1 receptor (MC1R) exert beneficial actions in experimental membranous nephropathy with reduced proteinuria, reduced oxidative stress, improved glomerular morphology and function. Our hypothesis is that MC1R activation in podocytes elicits beneficial effects by promoting stress fibers and maintaining podocyte viability. To test the hypothesis, we cultured podocytes and used highly specific agonists for the MC1R. The podocytes were subjected to the nephrotic-inducing agent puromycin aminonucleoside and downstream effects of MC1R activation on podocyte survival; antioxidant defense and cytoskeleton dynamics were studied. To increase the response and enhance the intracellular signals, podocytes were transduced to overexpress MC1R. We show that puromycin promotes MC1R expression in podocytes and that activation of the MC1R promotes an increase of catalase activity and reduces oxidative stress, which results in dephosphorylation of p190RhoGAP and formation of stress fibers through RhoA. In addition, MC1R agonists protects against apoptosis. Together, these mechanisms protect the podocyte against puromycin. Our findings strongly support the hypothesis that selective MC1R activating agonists protect podocytes and may therefore be useful to treat patients with nephrotic syndromes commonly considered as podocytopathies.
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| 7. |
- Ingelsten, Madeleine, 1978, et al.
(författare)
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Postischemic Inflammatory Response in an Auxiliary Liver Graft Predicts Renal Graft Outcome in Sensitized Patients
- 2011
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 91:8, s. 888-894
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Tidskriftsartikel (refereegranskat)abstract
- Background. The liver is considered a tolerogenic organ that favors the induction of peripheral tolerance and protects other organs from the same donor from rejection. This has been exploited in combined auxiliary liver-kidney transplantation, where a renal graft is transplanted against a positive crossmatch under the protection of a liver transplanted from the same donor. Methods. To elucidate mechanisms behind the liver protective effect, we studied early transcriptional changes of inflammatory mediators in the grafts during combined auxiliary liver-kidney transplantation using microarrays and real-time polymerase chain reaction. The results were correlated to clinical data. Results. Liver and kidney grafts both exhibited an upregulation of the leukocyte-recruiting chemokines CCL2, CCL3, and CCL4. Notably, liver grafts strongly upregulated CCL20, a dendritic cell, and T-cell recruiting chemokine. By comparing the gene expression in liver grafts with the clinical outcome, we found that 14 of 45 investigated inflammatory genes were expressed significantly higher in patients without early rejection when compared with those with early rejections. This included the above-mentioned chemokines and the T-cell-recruiting CX3CL1, NFKB1, and the tolerance-inducing gene indoleamine 2,3-dioxygenase. Conclusions. In this study, the protective role of the liver was associated with a proinflammatory reaction within this organ after ischemia-reperfusion. In particular, we found an increased expression of leukocyte-recruiting chemokines in patients without rejection, indicating a protective role of host inflammatory cells infiltrating the auxiliary liver graft in presensitized patients. Second, gene expression profiling of transplant biopsies shortly after reperfusion predicted the risk of early rejection in these patients.
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| 8. |
- Khramova, Alina, 1989, et al.
(författare)
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Proteoglycans contribute to the functional integrity of the glomerular endothelial cell surface layer and are regulated in diabetic kidney disease
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- All capillary endothelia, including those of the glomeruli, have a luminal cell surface layer (ESL) consisting of glycoproteins, glycolipids, proteoglycans (PGs) and glycosaminoglycans. Previous results have demonstrated that an intact ESL is necessary for a normal filtration barrier and damage to the ESL coupled to proteinuria is seen for example in diabetic kidney disease (DKD). We used the principles of ion exchange chromatography in vivo to elute the highly negatively charged components of the ESL with a 1M NaCl solution in rats. Ultrastructural morphology and renal function were analyzed and 17 PGs and hyaluronan were identified in the ESL. The high salt solution reduced the glomerular ESL thickness, led to albuminuria and reduced GFR. To assess the relevance of ESL in renal disease the expression of PGs in glomeruli from DKD patients in a next generation sequencing cohort was investigated. We found that seven of the homologues of the PGs identified in the ESL from rats were differently regulated in patients with DKD compared to healthy subjects. The results show that proteoglycans and glycosaminoglycans are essential components of the ESL, maintaining the permselective properties of the glomerular barrier and thus preventing proteinuria. © 2021, The Author(s).
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| 9. |
- Sörensson, Jenny, 1972, et al.
(författare)
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Synthesis of sulfated proteoglycans by bovine glomerular endothelial cells in culture
- 2003
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Ingår i: Am J Physiol Renal Physiol. ; 284:2
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that proteinuria is caused by alterations of the charge selectivity of the basement membrane and/or the epithelial cell layer (podocytes). However, recent findings suggest that the endothelial luminal surface coat, consisting of proteoglycans with their connected glycosaminoglycan (GAG) branches and glycoproteins, may contribute to the permselectivity. Therefore, we wanted to investigate the effects on endothelial GAG synthesis during normal and pathological conditions. We treated glomerular endothelial cell cultures with puromycin aminonucleoside (PAN, a nephrosis-inducing agent) or interleukin-1beta (IL-1beta) for a total of 72 h and compared the metabolic turnover and incorporation of [(35)S]sulfate during the last 2 days. In control cultures, the GAG content in the media supernatants increased 66 +/- 6% (mean +/- SE) between 12 and 42 h of incubation with radioactivity (P < 0.01, n = 8). The content of (35)S-labeled GAGs in the media was reduced by 31 +/- 1% by PAN (P < 0.001, n = 8) and increased by 141 +/- 15% by 10 U/ml IL-1beta (P < 0.01, n = 8). Treatment with enzymes revealed a dominance of heparan, chondroitin, and dermatan sulfate GAGs. Thus the glomerular endothelial cell production of GAGs was increased by IL-1beta and reduced by PAN. Therefore, it is conceivable that certain nephrotic conditions may be due to endothelial dysfunction, rather than other renal causes.
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| 10. |
- Zhou, Alex-Xianghua, et al.
(författare)
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Renal Endothelial Single-Cell Transcriptomics Reveals Spatiotemporal Regulation and Divergent Roles of Differential Gene Transcription and Alternative Splicing in Murine Diabetic Nephropathy
- 2024
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 25:8
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Tidskriftsartikel (refereegranskat)abstract
- Endothelial cell (EC) injury is a crucial contributor to the progression of diabetic kidney disease (DKD), but the specific EC populations and mechanisms involved remain elusive. Kidney ECs (n = 5464) were collected at three timepoints from diabetic BTBRob/ob mice and non-diabetic littermates. Their heterogeneity, transcriptional changes, and alternative splicing during DKD progression were mapped using SmartSeq2 single-cell RNA sequencing (scRNAseq) and elucidated through pathway, network, and gene ontology enrichment analyses. We identified 13 distinct transcriptional EC phenotypes corresponding to different kidney vessel subtypes, confirmed through in situ hybridization and immunofluorescence. EC subtypes along nephrons displayed extensive zonation related to their functions. Differential gene expression analyses in peritubular and glomerular ECs in DKD underlined the regulation of DKD-relevant pathways including EIF2 signaling, oxidative phosphorylation, and IGF1 signaling. Importantly, this revealed the differential alteration of these pathways between the two EC subtypes and changes during disease progression. Furthermore, glomerular and peritubular ECs also displayed aberrant and dynamic alterations in alternative splicing (AS), which is strongly associated with DNA repair. Strikingly, genes displaying differential transcription or alternative splicing participate in divergent biological processes. Our study reveals the spatiotemporal regulation of gene transcription and AS linked to DKD progression, providing insight into pathomechanisms and clues to novel therapeutic targets for DKD treatment.
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