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Annual Review of Physiology Feb 2024Mitochondria play a key role in kidney physiology and pathology. They produce ATP to fuel energy-demanding water and solute reabsorption processes along the nephron.... (Review)
Review
Mitochondria play a key role in kidney physiology and pathology. They produce ATP to fuel energy-demanding water and solute reabsorption processes along the nephron. Moreover, mitochondria contribute to cellular health by the regulation of autophagy, (oxidative) stress responses, and apoptosis. Mitochondrial abundance is particularly high in cortical segments, including proximal and distal convoluted tubules. Dysfunction of the mitochondria has been described for tubulopathies such as Fanconi, Gitelman, and Bartter-like syndromes and renal tubular acidosis. In addition, mitochondrial cytopathies often affect renal (tubular) tissues, such as in Kearns-Sayre and Leigh syndromes. Nevertheless, the mechanisms by which mitochondrial dysfunction results in renal tubular diseases are only scarcely being explored. This review provides an overview of mitochondrial dysfunction in the development and progression of kidney tubulopathies. Furthermore, it emphasizes the need for further mechanistic investigations to identify links between mitochondrial function and renal electrolyte reabsorption.
Topics: Humans; Kidney Tubules; Bartter Syndrome; Kearns-Sayre Syndrome; Kidney Diseases; Mitochondria
PubMed: 38012047
DOI: 10.1146/annurev-physiol-042222-025000 -
Redox Biology Dec 2023Diabetic tubulopathy (DT) is a recently recognized key pathology of diabetic kidney disease (DKD). The mitochondria-centric view of DT is emerging as a vital...
Diabetic tubulopathy (DT) is a recently recognized key pathology of diabetic kidney disease (DKD). The mitochondria-centric view of DT is emerging as a vital pathological factor in different types of metabolic diseases, such as DKD. Finerenone (FIN), a novel non-steroidal mineralocorticoid receptor antagonist, attenuates kidney inflammation and fibrosis in DKD, but the precise pathomechanisms remain unclear. The role of mineralocorticoid receptor (MR) in perturbing mitochondrial function via the PI3K/Akt/eNOS signaling pathway, including mitochondrial dynamics and mitophagy, was investigated under a diabetic state and high glucose (HG) ambiance. To elucidate how the activation of MR provokes mitochondrial dysfunction in DT, human kidney proximal tubular epithelial (HK-2) cells were exposed to HG, and then mitochondrial dynamics, mitophagy, mitochondrial ROS (mitoROS), signaling molecules PI3K, Akt, Akt phosphorylation and eNOS were probed. The above molecules or proteins were also explored in the kidneys of diabetic and FIN-treated mice. FIN treatment reduced oxidative stress, mitochondrial fragmentation, and apoptosis while restoring the mitophagy via PI3K/Akt/eNOS signaling pathway in HK-2 cells exposed to HG ambiance and tubular cells of DM mice. These findings linked MR activation to mitochondrial dysfunction via PI3K/Akt/eNOS signaling pathway in DT and highlight a pivotal but previously undiscovered role of FIN in alleviating renal tubule injury for the treatment of DKD.
Topics: Humans; Mice; Animals; Proto-Oncogene Proteins c-akt; Mineralocorticoid Receptor Antagonists; Phosphatidylinositol 3-Kinases; Signal Transduction; Diabetic Nephropathies; Mitochondria; Diabetes Mellitus
PubMed: 37924663
DOI: 10.1016/j.redox.2023.102946 -
Kidney International Reports Aug 2023Lysozyme-associated nephropathy (LyN), a rare cause of kidney injury in patients with chronic myelomonocytic leukemia (CMML), has not been well described to date. We...
INTRODUCTION
Lysozyme-associated nephropathy (LyN), a rare cause of kidney injury in patients with chronic myelomonocytic leukemia (CMML), has not been well described to date. We report the clinicopathologic spectrum of LyN from a multi-institutional series.
METHOD
We identified 37 native kidney biopsies with LyN and retrospectively obtained clinicopathologic data.
RESULTS
Thirty-seven patients had a median age of 74 years and included 78% males. Their most common presentation was acute kidney injury (AKI) or AKI on chronic kidney disease (CKD) (66%) with median estimated glomerular filtration rate (eGFR) of 21.7 ml/min per 1.73 m, and proteinuria of 1.7 g. A minority (15%) had partial Fanconi syndrome. Serum lysozyme levels were elevated in all tested. Hematologic disorder ( = 28, 76%) was the most common etiology, including CMML ( = 15), acute myeloid leukemia ( = 5), and myelodysplastic syndrome (MDS) ( = 5). Nonhematologic causes ( = 5, 14%), included metastatic neuroendocrine carcinoma ( = 3), sarcoidosis, and leprosy. Etiology was unknown in 4 (11%). Pathology showed proximal tubulopathy with abundant hypereosinophilic intracytoplasmic inclusions, with characteristic staining pattern by lysozyme immunostain. Mortality was high (8/30). However, among the 22 alive, including 85% treated, 7 had improved kidney function, including 1 who discontinued dialysis and 6 with increase in eGFR >15 ml/min per 1.73 m compared with eGFR at the time of biopsy.
CONCLUSION
Increased awareness of the full clinicopathologic spectrum of LyN may lead to prompt diagnosis, earlier treatment, and potentially improved outcome of this rare entity.
PubMed: 37547521
DOI: 10.1016/j.ekir.2023.05.007 -
Nephrology, Dialysis, Transplantation :... Oct 2023Light chain proximal tubulopathy (LCPT) is a rare form of paraprotein-related disease, occurring in two main histopathological forms: crystalline and non-crystalline....
BACKGROUND
Light chain proximal tubulopathy (LCPT) is a rare form of paraprotein-related disease, occurring in two main histopathological forms: crystalline and non-crystalline. The clinicopathological features, treatment strategies and outcomes, especially of the non-crystalline form, are not well described.
METHODS
We conducted a single-centre retrospective case series of 12 LCPT patients, 5 crystalline and 7 non-crystalline, between 2005 and 2021.
RESULTS
The median age was 69.5 years (range 47-80). Ten patients presented with CKD and significant proteinuria (median estimated glomerular filtration rate of 43.5 ml/min/1.73 m2; urine protein:creatinine ratio 328 mg/mmol). Only six patients had known haematological disease at the time of renal biopsy. Multiple myeloma (MM) was diagnosed in seven patients cases and monoclonal gammopathy of renal significance (MGRS) in five patients. A clone was detected in all cases combining serum/urine electrophoresis and free light chain (LC) assays. Crystalline and non-crystalline variants had similar clinical presentations. For the non-crystalline variant, a diagnosis was reached based on a combination of CKD without another cause, haematological workup, LC restriction on immunofluorescence and abnormalities on electron microscopy (EM). Nine of 12 patients received clone-directed treatment. Patients who achieved haematological response (including all non-crystalline LCPT) had improved renal outcomes over a median follow-up of 79 months.
CONCLUSIONS
The non-crystalline variant may go unrecognised because of its subtle histopathological features and requires EM to distinguish it from 'excessive LC resorption without tubular injury'. Clone-directed treatment with good haematological response improves renal outcomes in both variants but limited data exist in MGRS. Multicentre prospective studies are needed to better define the clinicopathological characteristics associated with poor outcomes and optimize treatment strategies in patients with MGRS.
Topics: Humans; Middle Aged; Aged; Aged, 80 and over; Retrospective Studies; Kidney Diseases; Kidney; Multiple Myeloma; Immunoglobulin Light Chains; Renal Insufficiency, Chronic; Paraproteinemias
PubMed: 37120733
DOI: 10.1093/ndt/gfad085 -
Frontiers in Genetics 2024Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and... (Review)
Review
Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.
PubMed: 38606357
DOI: 10.3389/fgene.2024.1381174 -
AIDS (London, England) Jun 2024To evaluate the efficacy and safety of 96 weeks of bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) treatment in participants switching from dolutegravir... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate the efficacy and safety of 96 weeks of bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) treatment in participants switching from dolutegravir (DTG)-based therapy.
DESIGN
Studies 1489 (NCT02607930) and 1490 (NCT02607956) were phase 3 randomized, double-blind, active-controlled, first-line therapy trials in people with HIV-1. After 144 weeks of DTG-based or B/F/TAF treatment, participants could enter a 96-week open-label extension (OLE) of B/F/TAF.
METHODS
A pooled analysis evaluated viral suppression (HIV-1 RNA <50 copies/ml) and changes in CD4 + cell count at OLE Weeks 48 and 96, treatment-emergent resistance, safety, and tolerability after switch from a DTG-based regimen to B/F/TAF. Outcomes by prior treatment were summarized using descriptive statistics and compared by two-sided Wilcoxon rank sum test.
RESULTS
At OLE Week 96, participants who switched to B/F/TAF ( N = 519) maintained high levels of virologic suppression (99.5 and 99.1% in those switching from DTG/abacavir/lamivudine and DTG+F/TAF, respectively) and CD4 + cell count, with no treatment-emergent resistance to B/F/TAF. Twenty-one participants experienced drug-related adverse events after switching, with diarrhea, weight gain, and headache occurring most commonly. There were no cases of proximal renal tubulopathy, drug-related Grade 4 adverse events, or serious adverse events. Two participants discontinued B/F/TAF due to treatment-related adverse events. Participants who switched from DTG/abacavir/lamivudine experienced statistically significant greater weight gain than those who switched from DTG+F/TAF; however, median weight change from the blinded phase baseline to OLE Week 96 was numerically similar across treatment groups.
CONCLUSION
This medium-term analysis demonstrates the safety and efficacy of switching to B/F/TAF from a DTG-containing regimen in people with HIV-1.
Topics: Adult; Aged; Female; Humans; Male; Middle Aged; Young Adult; Adenine; Alanine; Amides; Anti-HIV Agents; CD4 Lymphocyte Count; Double-Blind Method; Drug Substitution; Drug-Related Side Effects and Adverse Reactions; Emtricitabine; Heterocyclic Compounds, 3-Ring; Heterocyclic Compounds, 4 or More Rings; HIV Infections; HIV-1; Oxazines; Piperazines; Pyridones; Tenofovir; Treatment Outcome; Viral Load
PubMed: 38349226
DOI: 10.1097/QAD.0000000000003865 -
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 -
Kidney Medicine May 2024Light-chain proximal tubulopathy (LCPT) is typically characterized by the intracytoplasmic deposition of light chains within the proximal tubular epithelial cells, which...
Light-chain proximal tubulopathy (LCPT) is typically characterized by the intracytoplasmic deposition of light chains within the proximal tubular epithelial cells, which is usually classified into crystalline and noncrystalline subgroups. Membranous nephropathy (MN) is a common glomerular disease characterized by diffused subepithelial electron-dense deposits along the capillary loop accompanied by the effacement and microvillus transformation of the foot process. Here, we report a biopsy-confirmed case of a concurrence of LCPT with crystals (κ light chains restricted) and antigen-undetermined MN in a male patient. The patient presented with low-molecular-weight proteinuria, increased serum creatinine levels, and incomplete Fanconi syndrome. To our knowledge, this is the first report of a concurrence of LCPT and independent MN of unknown target antigens, which may enrich our recognition of monoclonal gammopathy of renal significance with synchronous MN.
PubMed: 38720788
DOI: 10.1016/j.xkme.2024.100816 -
Renal Failure Dec 2024Light-chain proximal tubulopathy (LCPT) is a rare disease characterized by the accumulation of monoclonal light chains within proximal tubular cells. This study aimed...
Light-chain proximal tubulopathy (LCPT) is a rare disease characterized by the accumulation of monoclonal light chains within proximal tubular cells. This study aimed to investigate the clinical characteristics of LCPT from a single Chinese nephrology referral center. Patients with kidney biopsy-proven isolated LCPT between 2016 and 2022 at Peking University First Hospital were retrospectively included. Clinical data, kidney pathological type, treatment, and prognosis were analyzed. Nineteen patients were enrolled, the mean age at diagnosis was 57 ± 11 and the sex ratio was 6/13 (female/male). Mean proteinuria was 2.44 ± 1.89 g/24 hr and the mean estimated glomerular filtration rate (eGFR) at the point of biopsy was 59.640 ± 27.449 ml/min/1.73 m. κ-restriction (84%) was dominant among LCPTs. An abnormal free light chain ratio was observed in 86% of the patients. Proximal tubulopathy with cytoplasmic inclusions accounted for the majority (53%), followed by tubulopathy associated with interstitial inflammation reaction (26%), proximal tubulopathy without cytoplasmic inclusions (16%), and proximal tubulopathy with lysosomal indigestion/constipation (5%). One patient presented with acute kidney injury and 16 patients presented with chronic kidney disease. Regarding follow-up, patients received bortezomib-based or R-CHOP chemotherapy or supportive treatment only. The mean follow-up time was 22 ± 16 months, and the mean eGFR was 63.098 ± 27.439 ml/min/1.73 m at the end of follow-up. These patients showed improved or stable kidney function. This is the first case series report of LCPT in four different pathological types in northern China. Clone-targeted chemotherapy may help preserve the kidney function in these patients.
Topics: Humans; Male; Female; Retrospective Studies; Nephrology; Kidney Tubules, Proximal; Kidney Diseases; Kidney; Renal Insufficiency, Chronic
PubMed: 38374684
DOI: 10.1080/0886022X.2023.2283587