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International Journal of Molecular... Jan 2023Cadmium (Cd) is a toxic metal that accumulates in kidneys, especially in the proximal tubular epithelial cells, where virtually all proteins in the glomerular...
Cadmium (Cd) is a toxic metal that accumulates in kidneys, especially in the proximal tubular epithelial cells, where virtually all proteins in the glomerular ultrafiltrate are reabsorbed. Here, we analyzed archived data on the estimated glomerular filtration rate (eGFR) and excretion rates of Cd (E), total protein (E), albumin (E), β-microglobulin (E), and α1-microglobulin (E), which were recorded for residents of a Cd contamination area and a low-exposure control area of Thailand. Excretion of Cd and all proteins were normalized to creatinine clearance (C) as E/C and E/C to correct for differences among subjects in the number of surviving nephrons. Low eGFR was defined as eGFR ≤ 60 mL/min/1.73 m, while proteinuria was indicted by E/C ≥ 20 mg/L of filtrate. E/C varied directly with E/C (β = 0.263, < 0.001) and age (β = 0.252, < 0.001). In contrast, eGFR values were inversely associated with E/C (β = -0.266, < 0.001) and age (β = -0.558, < 0.001). At E/C > 8.28 ng/L of filtrate, the prevalence odds ratios for proteinuria and low eGFR were increased 4.6- and 5.1-fold, respectively ( < 0.001 for both parameters). Thus, the eGFR and tubular protein retrieval were both simultaneously diminished by Cd exposure. Of interest, E/C was more closely correlated with E/C ( = 0.507), E ( = 0.430), and E/C ( = 0.364) than with E/C ( = 0.152). These data suggest that Cd may differentially reduce the ability of tubular epithelial cells to reclaim proteins, resulting in preferential reabsorption of albumin.
Topics: Humans; Cadmium; Proteinuria; Kidney; Kidney Glomerulus; Glomerular Filtration Rate; beta 2-Microglobulin; Albumins; Creatinine
PubMed: 36768208
DOI: 10.3390/ijms24031893 -
Clinical Nephrology. Case Studies 2023Dent's disease is an X-linked recessive disease characterized by proximal tubulopathy with low-molecular weight proteinuria, hypercalciuria, nephrolithiasis,...
Dent's disease is an X-linked recessive disease characterized by proximal tubulopathy with low-molecular weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and kidney failure. It is mainly caused by mutations in the or genes, and only ~ 250 families have been identified with these mutations. We present a 31-year-old male referred to a nephrology consultation due to elevated serum creatinine and a history of nephrolithiasis. Complementary evaluation revealed protein/creatinine ratio of 1.9 g/g and albumin/creatinine ratio of 0.5 g/g, hypercalciuria and medullary nephrocalcinosis. These findings raised the suspicion of Dent's disease, which was confirmed by genetic testing. A missense mutation in the gene (c.810C>G, p.(Ser270Arg)), not previously reported in populational databases, was identified. During the evaluation of the patient, it came to our attention that a first-degree male cousin was being followed in our kidney transplantation unit. Given the unknown etiology of his chronic kidney disease, genetic testing was performed, identifying the same mutation. This case highlights the importance of considering the diagnosis of Dent's disease in the setting of a male patient with chronic kidney disease of unknown etiology, low-molecular-weight proteinuria, hypercalciuria, and nephrocalcinosis. Despite progression to end-stage kidney failure in a significant portion of male patients, there are no reports of recurrence after kidney transplantation.
PubMed: 36688186
DOI: 10.5414/CNCS110975 -
Renal Failure Dec 2023Crystal-storing histiocytosis (CSH), light chain proximal tubulopathy (LCPT), and light chain crystalline podocytopathy (LCCP) are rare complications of multiple myeloma... (Review)
Review
Combined crystal-storing histiocytosis, light chain proximal tubulopathy, and light chain crystalline podocytopathy in a patient with multiple myeloma: a case report and literature review.
BACKGROUND
Crystal-storing histiocytosis (CSH), light chain proximal tubulopathy (LCPT), and light chain crystalline podocytopathy (LCCP) are rare complications of multiple myeloma (MM) or monoclonal gammopathy of renal significance, and their diagnoses are challenging.
CASE PRESENTATION
In this case, a 69-year-old Chinese woman presented with suspicious Fanconi syndrome with renal insufficiency. Immunofixation electrophoresis of both serum and urine revealed elevated immunoglobulin G kappa (IgGkappa) and kappa light chain. Bone marrow aspirate revealed 15% plasma cells with considerable cytoplasmic granular inclusions and needle-shaped crystals. Renal biopsy confirmed the final pathologic diagnosis of kappa-restricted CSH, combined LCPT and LCCP by immunoelectron microscopy. A number of special casts were present which could easily be misdiagnosed as light chain cast nephropathy. Immunofluorescence on frozen tissue presented false negative for kappa light chain, as ultimately proven by paraffin-embedded tissue after pronase digestion. MM and CSH were diagnosed, and two cycles of chemotherapy were given. The patient subsequently refused further chemotherapy, and her renal function remained relatively stable during a 2.5-year follow-up period.
CONCLUSIONS
In conclusion, we report a rare case of generalized kappa-restricted CSH involving bone marrow and kidney, combined with LCPT and LCCP, provide a comprehensive summary of renal CSH, and propose a new nomenclature of monoclonal immunoglobulin-induced crystalline nephrology. The presentation of monoclonal immunoglobulin and Fanconi syndrome should suggest the presence of monoclonal immunoglobulin-induced crystalline nephrology. Use of paraffin-embedded tissue after pronase digestion and immunoelectron microscopy is beneficial to improve the sensitivity of diagnosis.
Topics: Humans; Female; Aged; Multiple Myeloma; Fanconi Syndrome; Pronase; Kidney Diseases; Immunoglobulin kappa-Chains; Antibodies, Monoclonal; Histiocytosis
PubMed: 36632756
DOI: 10.1080/0886022X.2022.2145970 -
Annals of the New York Academy of... Mar 2023Magnesium is the fourth most abundant cation in the body. It plays a critical role in many biological processes, including the process of energy release. Paracellular... (Review)
Review
Magnesium is the fourth most abundant cation in the body. It plays a critical role in many biological processes, including the process of energy release. Paracellular transport of magnesium is mandatory for magnesium homeostasis. In addition to intestinal absorption that occurs in part across the paracellular pathway, magnesium is reabsorbed by the kidney tubule. The bulk of magnesium is reabsorbed through the paracellular pathway in the proximal tubule and the thick ascending limb of the loop of Henle. The finding that rare genetic diseases due to pathogenic variants in genes encoding specific claudins (CLDNs), proteins located at the tight junction that determine the selectivity and the permeability of the paracellular pathway, led to an awareness of their importance in magnesium homeostasis. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis is caused by a loss of function of CLDN16 or CLDN19. Pathogenic CLDN10 variants cause HELIX syndrome, which is associated with a severe renal loss of sodium chloride and hypermagnesemia. The present review summarizes the current knowledge of the mechanisms and factors involved in paracellular magnesium permeability. The review also highlights some of the unresolved questions that need to be addressed.
Topics: Humans; Magnesium; Nephrocalcinosis; Hypercalciuria; Homeostasis; Membrane Proteins; Claudins
PubMed: 36622354
DOI: 10.1111/nyas.14953 -
Cells Dec 2022Tubulopathy plays a central role in the pathophysiology of diabetic kidney disease (DKD). Under diabetic conditions, the kidney proximal tubule cells (KPTCs) are exposed... (Review)
Review
Tubulopathy plays a central role in the pathophysiology of diabetic kidney disease (DKD). Under diabetic conditions, the kidney proximal tubule cells (KPTCs) are exposed to an extensive amount of nutrients, most notably glucose; these nutrients deteriorate KPTCs function and promote the development and progression of DKD. Recently, the facilitative glucose transporter 2 (GLUT2) in KPTCs has emerged as a central regulator in the pathogenesis of DKD. This has been demonstrated by identifying its specific role in enhancing glucose reabsorption and glucotoxicity, and by deciphering its effect in regulating the expression of the sodium-glucose transporter 2 (SGLT2) in KPTCs. Moreover, reduction/deletion of KPTC-GLUT2 has been recently found to ameliorate DKD, raising the plausible idea of considering it as a therapeutic target against DKD. However, the underlying molecular mechanisms by which GLUT2 exerts its deleterious effects in KPTCs remain vague. Herein, we review the current findings on the proximal tubule GLUT2 biology and function under physiologic conditions, and its involvement in the pathophysiology of DKD. Furthermore, we shed new light on its cellular regulation during diabetic conditions.
Topics: Humans; Kidney; Kidney Tubules, Proximal; Glucose; Diabetic Nephropathies; Sodium-Glucose Transporter 2 Inhibitors
PubMed: 36611887
DOI: 10.3390/cells12010094 -
Kidney International Mar 2023Monoclonal immunoglobulin light chain (LC) crystalline inclusions within podocytes are rare, poorly characterized entities. To provide more insight, we now present the...
Monoclonal immunoglobulin light chain (LC) crystalline inclusions within podocytes are rare, poorly characterized entities. To provide more insight, we now present the first clinicopathologic series of LC crystalline podocytopathy (LCCP) encompassing 25 patients (68% male, median age 56 years). Most (80%) patients presented with proteinuria and chronic kidney disease, with nephrotic syndrome in 28%. Crystalline keratopathy and Fanconi syndrome were present in 22% and 10%, respectively. The hematologic condition was monoclonal gammopathy of renal significance (MGRS) in 55% and multiple myeloma in 45%. The serum monoclonal immunoglobulin was IgG κappa in 86%. Histologically, 60% exhibited focal segmental glomerulosclerosis (FSGS), often collapsing. Ultrastructurally, podocyte LC crystals were numerous with variable effacement of foot processes. Crystals were also present in proximal tubular cells as light chain proximal tubulopathy (LCPT) in 80% and in interstitial histiocytes in 36%. Significantly, frozen-section immunofluorescence failed to reveal the LC composition of crystals in 88%, requiring paraffin-immunofluorescence or immunohistochemistry, with identification of kappa LC in 87%. The LC variable region gene segment, determined by mass spectrometry of glomeruli or bone marrow plasma cell sequencing, was IGKV1-33 in four and IGKV3-20 in one. Among 21 patients who received anti-plasma cell-directed chemotherapy, 50% achieved a kidney response, which depended on a deep hematologic response. After a median follow-up of 36 months, 26% progressed to kidney failure and 17% died. The mean kidney failure-free survival was 57.6 months and was worse in those with FSGS. In sum, LCCP is rare, mostly associates with IgG κappa MGRS, and frequently has concurrent LCPT, although Fanconi syndrome is uncommon. Paraffin-immunofluorescence and electron microscopy are essential to prevent misdiagnosis as primary FSGS since kidney survival depends on early diagnosis and subsequent clone-directed therapy.
Topics: Humans; Male; Middle Aged; Female; Glomerulosclerosis, Focal Segmental; Fanconi Syndrome; Paraffin; Kidney; Kidney Diseases; Renal Insufficiency; Immunoglobulin G
PubMed: 36581019
DOI: 10.1016/j.kint.2022.11.026 -
EJHaem Nov 2022Due to differences in the protein folding mechanisms, it is exceedingly rare for amyloid light chain (AL) amyloidosis and monoclonal gammopathy of renal significance...
Due to differences in the protein folding mechanisms, it is exceedingly rare for amyloid light chain (AL) amyloidosis and monoclonal gammopathy of renal significance (MGRS) to coexist. We herein report the first case of concurrent AL amyloidosis and a subclass of MGRS, light chain proximal tubulopathy (LCPT). The 53-year-old female was diagnosed with smoldering myeloma immunoglobulin G and AL amyloidosis with deposits in fat and gastrointestinal tissue. The kidney biopsy did not show amyloid deposits but electron microscopy revealed the presence of LCPT with crystal formation in proximal tubular epithelial cells. This case illustrates the complex pathophysiology of protein deposition in monoclonal gammopathies.
PubMed: 36467828
DOI: 10.1002/jha2.555 -
Clinical Nephrology Jan 2023Light chain proximal tubulopathy (LCPT) is a rare M-proteinemia-related nephropathy. Non-crystalline LCPT is even rarer. We herein report an unusual case of renal... (Review)
Review
BACKGROUND
Light chain proximal tubulopathy (LCPT) is a rare M-proteinemia-related nephropathy. Non-crystalline LCPT is even rarer. We herein report an unusual case of renal dysfunction and proteinuria due to κ-restricted and non-crystalline LCPT in a context of monoclonal gammopathy of renal significance (MGRS) without Fanconi syndrome (FS).
CASE PRESENTATION
A 67-year-old man was admitted for a 2-year history of proteinuria and renal dysfunction. Fanconi syndrome (FS) was not observed. He was noted to have IgG-κ M protein, and the previous bone marrow biopsy revealed that atypical plasma cells accounted for 1.5% of the cells, which did not meet the diagnostic criteria for multiple myeloma. A renal biopsy revealed proximal tubular injury, including increased lysosomes with irregular contours and a mottled appearance without crystalline structure and the accumulation of κ light chains. He was diagnosed with non-crystalline LCPT with MGRS. Concurrently, we reviewed the non-crystalline LCPT cases previously published in the literature. Our patient finally received chemotherapy with a bortezomib and dexamethasone regimen. The patient did not seem to achieve evident nephrological and hematological remission after chemotherapy, but he was in a stable condition.
CONCLUSION
Very few similar cases are reported in the literature. It is considered crucial to enhance our knowledge about these cases to establish the definition of the non-crystalline LCPT entity and allow for early diagnosis. Chemotherapy may not be necessary for all patients to maintain good renal function. Future prospective clinical research studies are necessary.
Topics: Male; Humans; Aged; Fanconi Syndrome; Paraproteinemias; Kidney; Kidney Diseases; Multiple Myeloma; Proteinuria
PubMed: 36444974
DOI: 10.5414/CN110883 -
Nephrology, Dialysis, Transplantation :... May 2023Dent's disease type 1 (DD1) is a rare X-linked nephropathy caused by CLCN5 mutations, characterized by proximal tubule dysfunction, including low molecular weight...
BACKGROUND
Dent's disease type 1 (DD1) is a rare X-linked nephropathy caused by CLCN5 mutations, characterized by proximal tubule dysfunction, including low molecular weight proteinuria (LMWP), hypercalciuria, nephrolithiasis-nephrocalcinosis, progressive chronic kidney disease (CKD) and kidney failure (KF). Current management is symptomatic and does not prevent disease progression. Here we describe the contemporary DD1 picture across Europe to highlight its unmet needs.
METHODS
A physician-based anonymous international e-survey supported by several European nephrology networks/societies was conducted. Questions focused on DD1 clinical features, diagnostic procedure and mutation spectra.
RESULTS
A total of 207 DD1 male patients were reported; clinical data were available for 163 with confirmed CLCN5 mutations. Proteinuria was the most common manifestation (49.1%). During follow-up, all patients showed LMWP, 66.4% nephrocalcinosis, 44.4% hypercalciuria and 26.4% nephrolithiasis. After 5.5 years, ≈50% of patients presented with renal dysfunction, 20.7% developed CKD stage ≥3 and 11.1% developed KF. At the last visit, hypercalciuria was more frequent in paediatric patients than in adults (73.4% versus 19.0%). Conversely, nephrolithiasis, nephrocalcinosis and renal dysfunction were more prominent in adults. Furthermore, CKD progressed with age. Despite no clear phenotype/genotype correlation, decreased glomerular filtration rate was more frequent in subjects with CLCN5 mutations affecting the pore or CBS domains compared with those with early-stop mutations.
CONCLUSIONS
Results from this large DD1 cohort confirm previous findings and provide new insights regarding age and genotype impact on CKD progression. Our data strongly support that DD1 should be considered in male patients with CKD, nephrocalcinosis/hypercalciuria and non-nephrotic proteinuria and provide additional support for new research opportunities.
Topics: Male; Humans; Nephrocalcinosis; Dent Disease; Hypercalciuria; Kidney Calculi; Mutation; Europe; Renal Insufficiency; Renal Insufficiency, Chronic; Proteinuria; Chloride Channels
PubMed: 36441012
DOI: 10.1093/ndt/gfac310 -
Animals : An Open Access Journal From... Nov 2022Acquired canine proximal renal tubulopathy (Fanconi syndrome) related to excessive ingestion of jerky treats has been recognized since 2007. This study aimed to improve...
Acquired canine proximal renal tubulopathy (Fanconi syndrome) related to excessive ingestion of jerky treats has been recognized since 2007. This study aimed to improve knowledge about the syndrome’s characteristics, especially long-term outcome. By reaching out to veterinarians and dog owners, dogs suspected of jerky induced Fanconi syndrome were identified. The dog’s medical records were reviewed, and owners interviewed. Data was analyzed using linear mixed models (p < 0.05 was considered statistically significant) and descriptive statistics are reported. Thirty dogs, median body weight 6.8 (range 1.2−59) kg and age 6.5 (0.5−14) years, were enrolled as suspected cases based on history of jerkey ingestion and confirmed normoglycemic/hypoglycemic glycosuria. Clinical signs included polydipsia (23/30), polyuria (21/30), lethargy (19/30), weight loss (15/30), hyporexia (11/30), vomiting (7/30), diarrhea (7/30) and no clinical signs (2/30). Para-clinical findings included azotemia (6/28), hypophosphatemia (9/25), metabolic acidosis (3/8), hypokalemia (6/20), proteinuria (13/26), aminoaciduria (4/4), hematuria (22/29) and ketonuria (7/27). Clinical signs resolved in 22/28 within 11 (0.3−52) weeks and glycosuria resolved in 28/30 within 6.5 (1−31) weeks. There were no associations between serum creatinine and urea and the amount/duration of jerky ingestion. Serum symmetric dimethylarginine concentrations were only available for a few dogs, therefore no conclusion was achieved on a possible association with duration of jerky ingestion. Apart from a larger percentage of dogs achieving complete recovery, the current findings are in agreement with previous reports.
PubMed: 36428419
DOI: 10.3390/ani12223192