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BioRxiv : the Preprint Server For... Feb 2024Chronic kidney disease (CKD) is associated with renal metabolic disturbances, including impaired fatty acid oxidation (FAO). Nicotinamide adenine dinucleotide (NAD ) is...
Chronic kidney disease (CKD) is associated with renal metabolic disturbances, including impaired fatty acid oxidation (FAO). Nicotinamide adenine dinucleotide (NAD ) is a small molecule that participates in hundreds of metabolism-related reactions. NAD levels are decreased in CKD, and NAD supplementation is protective. However, both the mechanism of how NAD supplementation protects from CKD, as well as the cell types most responsible, are poorly understood. Using a mouse model of Alport syndrome, we show that nicotinamide riboside (NR), an NAD precursor, stimulates renal peroxisome proliferator-activated receptor α signaling and restores FAO in the proximal tubules, thereby protecting from CKD in both sexes. Bulk RNA-sequencing shows that renal metabolic pathways are impaired in Alport mice and dramatically activated by NR in both sexes. These transcriptional changes are confirmed by orthogonal imaging techniques and biochemical assays. Single nuclei RNA-sequencing and spatial transcriptomics, both the first of their kind from Alport mice, show that NAD supplementation restores FAO in the proximal tubules with minimal effects on the podocytes. Finally, we also report, for the first time, sex differences at the transcriptional level in this Alport model. Male Alport mice had more severe inflammation and fibrosis than female mice at the transcriptional level. In summary, the data herein identify both the protective mechanism and location of NAD supplementation in this model of CKD.
PubMed: 38464264
DOI: 10.1101/2024.02.26.580911 -
Research Square Feb 2024Personalized disease models are crucial for assessing the specific response of diseased cells to drugs, particularly novel biological therapeutics. Extracellular...
BACKGROUND
Personalized disease models are crucial for assessing the specific response of diseased cells to drugs, particularly novel biological therapeutics. Extracellular vesicles (EVs), nanosized vesicles released by cells for intercellular communication, have gained therapeutic interest due to their ability to reprogram target cells. We here utilized urinary podocytes obtained from children affected by steroid-resistant nephrotic syndrome with characterized genetic mutations as a model to test the therapeutic potential of EVs derived from kidney progenitor cells.
METHODS
EVs were isolated from kidney progenitor cells (nKPCs) derived from the urine of a preterm neonate. Three lines of urinary podocytes obtained from nephrotic patients' urine and a line of Alport patient podocytes were characterized and used to assess albumin permeability in response to various drugs or to nKPC-EVs. RNA sequencing was conducted to identify commonly modulated pathways.
RESULTS
Podocytes appeared unresponsive to pharmacological treatments, except for a podocyte line demonstrating responsiveness, in alignment with the patient's clinical response at 48 months. At variance, treatment with the nKPC-EVs was able to significantly reduce permeability in all the steroid-resistant patients-derived podocytes as well as in the line of Alport-derived podocytes. RNA sequencing of nKPC-EV-treated podocytes revealed the common upregulation of two genes (small ubiquitin-related modifier 1 (SUMO1) and Sentrin-specific protease 2 (SENP2)) involved in the SUMOylation pathway, a process recently demonstrated to play a role in slit diaphragm stabilization. Gene ontology analysis on podocyte expression profile highlighted cell-to-cell adhesion as the primary upregulated biological activity in treated podocytes.
CONCLUSIONS
nKPCs emerge as a promising non-invasive source of EVs with potential therapeutic effects on podocyte dysfunction. Furthermore, our findings suggest the possibility of establishing a non-invasive in vitro model for screening regenerative compounds on patient-derived podocytes.
PubMed: 38464119
DOI: 10.21203/rs.3.rs-3959549/v1 -
Medicine Mar 2024Genetic factors contribute to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Advances in genetic testing have enabled the identification of hereditary...
BACKGROUND
Genetic factors contribute to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Advances in genetic testing have enabled the identification of hereditary kidney diseases, including those caused by LMX1B mutations. LMX1B mutations can lead to nail-patella syndrome (NPS) or nail-patella-like renal disease (NPLRD) with only renal manifestations.
CASE PRESENTATION
The proband was a 13-year-old female who was diagnosed with nephrotic syndrome at the age of 6. Then she began intermittent hormone and drug therapy. When she was 13 years old, she was admitted to our hospital due to sudden chest tightness, which progressed to end-stage kidney disease (ESRD), requiring kidney replacement therapy. Whole-Exome Sequencing (WES) results suggest the presence of LMX1B gene mutation, c.737G > T, p.Arg246Leu. Tracing her family history, we found that her father, grandmother, uncle and 2 cousins all had hematuria, or proteinuria. In addition to the grandmother, a total of 9 members of the family performed WES. The members with kidney involved all carry the mutated gene. Healthy members did not have the mutated gene. It is characterized by co-segregation of genotype and phenotype. We followed the family for 9 year, the father developed ESRD at the age of 50 and started hemodialysis treatment. The rest patients had normal renal function. No extra-renal manifestations associated with NPS were found in any member of the family.
CONCLUSIONS
This study has successfully identified missense mutation, c.737G > T (p.Arg246Leu) in the homeodomain, which appears to be responsible for isolated nephropathy in the studied family. The arginine to leucine change at codon 246 likely disrupts the DNA-binding homeodomain of LMX1B. Previous research has documented 2 types of mutations at codon R246, namely R246Q and R246P, which are known to cause NPLRD. The newly discovered mutation, R246L, is likely to be another novel mutation associated with NPLRD, thus expanding the range of mutations at the crucial renal-critical codon 246 that contribute to the development of NPLRD. Furthermore, our findings suggest that any missense mutation occurring at the 246th amino acid position within the homeodomain of the LMX1B gene has the potential to lead to NPLRD.
Topics: Humans; Female; Adolescent; Transcription Factors; LIM-Homeodomain Proteins; Nephritis, Hereditary; Mutation; Kidney Failure, Chronic; Codon; China; Homeodomain Proteins; Nail-Patella Syndrome
PubMed: 38457557
DOI: 10.1097/MD.0000000000037442 -
Molecular Genetics & Genomic Medicine Mar 2024Alport syndrome (AS) is a genetically heterogeneous disorder resulting from mutations in the collagen IV genes COL4A3, COL4A4, and COL4A5. The genetic diagnosis of AS is...
BACKGROUND
Alport syndrome (AS) is a genetically heterogeneous disorder resulting from mutations in the collagen IV genes COL4A3, COL4A4, and COL4A5. The genetic diagnosis of AS is very important to make precise diagnosis and achieve optimal outcomes.
METHODS
In this study, 16 Chinese families with suspected AS were recruited after pedigree analysis, and the clinical presentations were analyzed by a nephrologist. The genetic diagnosis was performed by whole-exome sequencing (WES) and the disease-causing variants were confirmed by Sanger sequencing.
RESULTS
The cohort of probands included seven men and nine women, with a mean age of 19.9 years. Pathological analysis showed slight-to-moderate mesangial proliferation, and thin basement membrane was the main findings. Pathogenic variants were revealed by WES in each family, and the co-segregation with renal presentation was confirmed by PCR. In addition, RT-PCR analysis showed that the intronic variant led to aberrant splicing.
CONCLUSION
Our findings expand the spectrum of AS gene variation, which will inform genetic diagnosis and add to the theoretical basis for the prevention of AS.
Topics: Adult; Female; Humans; Male; Young Adult; Asian People; China; Collagen Type IV; Kidney; Nephritis, Hereditary
PubMed: 38433557
DOI: 10.1002/mgg3.2406 -
Archives of Iranian Medicine Jan 2024Hereditary nephritis (HN), including Alport syndrome (AS) and thin basement membrane nephropathy (TBMN), is a rare genetic cause of hematuria. A definitive diagnosis...
BACKGROUND
Hereditary nephritis (HN), including Alport syndrome (AS) and thin basement membrane nephropathy (TBMN), is a rare genetic cause of hematuria. A definitive diagnosis requires electron microscopy (EM). Therefore, the clinical characteristics of these conditions are less known. This study aimed to determine the percentage and clinicopathological features of HN in patients from a referral center in Iran.
METHODS
We checked kidney biopsy reports from 2007 to 2021 and extracted cases with HN. Fresh specimens of the cases diagnosed in the last two years were stained by immunofluorescence (IF) for collagen type IV alpha chains. EM findings in these cases were re-evaluated and categorized as diffuse glomerular basement membrane (GBM) thinning, definite, and suspicious features of AS.
RESULTS
We analyzed 3884 pathology reports of kidney biopsies from 2007 to 2021 and identified 210 patients (5.4%) with HN, with a mean age of 13.78±12.42 years old. Hematuria with proteinuria (53.3%), isolated hematuria (44.2%), and proteinuria with hematuria and increased creatinine (2.5%) were found in these patients. The re-evaluation of EM findings revealed GBM thinning, definite, and suspicious findings of AS in 37.5%, 43.8%, and 18.8% cases, respectively. The most common diagnosis in 32 cases after the IF study was X-linked AS (71.9%), and 6.2% of cases were autosomal recessive AS. TBMN and autosomal dominant AS remained the differential diagnoses in 21.9%.
CONCLUSION
It was found that EM is helpful for the primary diagnosis of patients with definite AS. Immunostaining improves the diagnostic sensitivity for the differentiation of those with suspicious EM findings and determines the inheritance pattern. However, a multidisciplinary approach for a subset of cases is required for the best diagnosis and management.
Topics: Humans; Infant; Child, Preschool; Child; Adolescent; Young Adult; Adult; Nephritis, Hereditary; Hematuria; Iran; Proteinuria; Referral and Consultation; Biopsy; Kidney
PubMed: 38431955
DOI: 10.34172/aim.2024.02 -
Physiological Reports Mar 2024The role of NRF2 in kidney biology has received considerable interest over the past decade. NRF2 transcriptionally controls genes responsible for cellular protection... (Review)
Review
The role of NRF2 in kidney biology has received considerable interest over the past decade. NRF2 transcriptionally controls genes responsible for cellular protection against oxidative and electrophilic stress and has anti-inflammatory functions. NRF2 is expressed throughout the kidney and plays a role in salt and water handling. In disease, animal studies show that NRF2 protects against tubulointerstitial damage and reduces interstitial fibrosis and tubular atrophy, and may slow progression of polycystic kidney disease. However, the role of NRF2 in proteinuric glomerular diseases is controversial. Although the NRF2 inducer, bardoxolone methyl (CDDO-Me), increases glomerular filtration rate in humans, it has not been shown to slow disease progression in diabetic kidney disease and Alport syndrome. Furthermore, bardoxolone methyl was associated with negative effects on fluid retention, proteinuria, and blood pressure. Several animal studies replicate findings of worsened proteinuria and a more rapid progression of kidney disease, although considerable controversy exists. It is clear that further study is needed to better understand the effects of NRF2 in the kidney. This review summarizes the available data to clarify the promise and risks associated with targeting NRF2 activity in the kidney.
Topics: Animals; Humans; NF-E2-Related Factor 2; Kidney; Diabetic Nephropathies; Proteinuria; Oleanolic Acid
PubMed: 38418382
DOI: 10.14814/phy2.15961 -
Nefrologia 2024Hereditary kidney diseases (HKD) are a frequent cause of chronic kidney disease, and their diagnosis has increased since the introduction of next generation sequencing...
BACKGROUND AND OBJECTIVE
Hereditary kidney diseases (HKD) are a frequent cause of chronic kidney disease, and their diagnosis has increased since the introduction of next generation sequencing (NGS). In 2018, the Multidisciplinary Unit for Hereditary Kidney Diseases of the Region of Murcia (UMERH-RM) was founded based on the genetic study of HKD. The objective of this study is to analyze the results obtained in the first 3 years of operation, and to analyze the clinical factors associated to a final genetic diagnosis.
MATERIALS AND METHODS
All the patients studied with the HKD gene panel were included. The characteristics between those who obtained a final genetic diagnosis and those who did not were compared.
RESULTS
A total of 360 patients were studied, detecting genetic variants in 164 not related patients (45.6%). 45 of these were variants of uncertain significance requiring a family co-segregation study, which was facilitated by the multidisciplinary unit. Overall, considering the results obtained with the NGS panel and the extended genomic studies, a final diagnostic yield of HRD of 33.3% (120/360) was achieved, and including incidental findings 35.6% (128/360). Two hundred and twenty-three patients with suspected Alport syndrome were studied. Diagnosis was confirmed in 28.5% (COL4A4 most frequent gene), more frequently women with an obvious compatible family history. They also had frequently microhematuria, although 5 patients without microhematuria confirmed the diagnosis. There were no differences in age, proteinuria, renal function, hearing loss, or ophthalmologic abnormalities. The most frequent finding in the renal biopsy was mesangial proliferation. We estimate that 39 patients avoided renal biopsy. A total of 101 patients with suspected PKD were also studied, 49.5% had a conclusive genetic result (most frequent gene PKD1), more frequently women, with larger kidney sizes (although 9 patients with normal kidney size confirmed diagnosis). Again, the most predictive characteristic of genetic outcome was family history.
CONCLUSIONS
The implementation of an NGS panel for HKD, together with the multidisciplinary approach to cases, has improved the diagnostic performance of HKD. In our sample, autosomal dominant Alport syndrome is of highest incidence. Ophthalmological and auditory examinations did not contribute to the diagnosis. We have seen a significant decrease in the indication of renal biopsies thanks to molecular diagnosis. The multidisciplinary approach, with the active participation of nephrologists, paediatricians, clinical and molecular geneticists, with insistence on adequate patient phenotyping and review of their family history, offers a better interpretation of genetic variants, allowing reclassification of the diagnosis of some nephropathies, thus improving their management and genetic advice.
Topics: Humans; Female; Nephritis, Hereditary; High-Throughput Nucleotide Sequencing; Mutation; Kidney; Hematuria
PubMed: 38418364
DOI: 10.1016/j.nefroe.2024.02.002 -
Molecular Genetics & Genomic Medicine Feb 2024X-linked Alport syndrome (XLAS) is an inherited renal disease caused by rare variants of COL4A5 on chromosome Xq22. Many studies have indicated that single nucleotide...
BACKGROUND
X-linked Alport syndrome (XLAS) is an inherited renal disease caused by rare variants of COL4A5 on chromosome Xq22. Many studies have indicated that single nucleotide variants (SNVs) in exons can disrupt normal splicing process of the pre-mRNA by altering various splicing regulatory signals. The male patients with XLAS have a strong genotype-phenotype correlation. Confirming the effect of variants on splicing can help to predict kidney prognosis. This study aimed to investigate whether single nucleotide substitutions, located within three bases at the 5' end of the exons or internal position of the exons in COL4A5 gene, cause aberrant splicing process.
METHODS
We analyzed 401 SNVs previously presumed missense and nonsense variants in COL4A5 gene by bioinformatics programs and identified candidate variants that may affect the splicing of pre-mRNA via minigene assays.
RESULTS
Our study indicated three of eight candidate variants induced complete or partial exon skipping. Variants c.2678G>C and c.2918G>A probably disturb classic splice sites leading to corresponding exon skipping. Variant c.3700C>T may disrupt splicing enhancer motifs accompanying with generation of splicing silencer sequences resulting in the skipping of exon 41.
CONCLUSION
Our study revealed that two missense variants positioned the first nucleotides of the 5' end of COL4A5 exons and one internal exonic nonsense variant caused aberrant splicing. Importantly, this study emphasized the necessity of assessing the effects of SNVs at the mRNA level.
Topics: Humans; Male; RNA Precursors; Mutation; RNA Splicing; Exons; Nephritis, Hereditary; Biological Assay; Nucleotides; Collagen Type IV
PubMed: 38400605
DOI: 10.1002/mgg3.2395 -
Cureus Jan 2024Alport syndrome, a rare genetic condition, can manifest various ocular abnormalities. This case report presents a unique instance of Alport syndrome where bilateral...
Alport syndrome, a rare genetic condition, can manifest various ocular abnormalities. This case report presents a unique instance of Alport syndrome where bilateral reduced visual acuity led to cataract surgery and subsequent central serous chorioretinopathy due to steroid treatment. By utilizing multiple imaging modalities, we aim to illustrate classical and atypical findings, addressing a literature gap and sharing our experience for educational purposes.
PubMed: 38389645
DOI: 10.7759/cureus.52768 -
Cureus Jan 2024A 13-year-old boy presented with hypoxia, microscopic hematuria, and elevated blood pressures. Persistent microscopic hematuria and hypertension led to investigation of...
A 13-year-old boy presented with hypoxia, microscopic hematuria, and elevated blood pressures. Persistent microscopic hematuria and hypertension led to investigation of glomerular and non-glomerular causes of hematuria. After reviewing his clinical course, family history, and laboratory testing, an additional test was sent, revealing the diagnosis.
PubMed: 38384656
DOI: 10.7759/cureus.52738