A Case of Rapidly Progressive Diabetic Nephropathy Induced by Osimertinib.

The number of patients with diabetic nephropathy is increasing worldwide and it is important to understand the underlying pathological mechanisms of the disease. In early stage diabetic nephropathy, the hyperglycemic environment leads to vascular endothelial cell damage, resulting in overexpression of vascular endothelial growth factor (VEGF) in podocytes and renal pathology of glomerular hypertrophy, glomerular basement membrane thickening, and mesangial hyperplasia. In diabetic nephropathy, renal thrombotic microangiopathy (TMA) develops and the nephropathy progressively worsens in some cases of severe glomerular podocyte damage. Further, receptor tyrosine kinase inhibitors (RTKIs) may suppress VEGF secretion via VEGF receptor-2 tyrosine kinase inhibition in podocytes, which results in renal TMA and rapid deterioration of diabetic nephropathy. Osimertinib, a third-generation irreversible epidermal growth factor receptor (EGFR)-TKI, is approved as a first-line treatment agent for metastatic or locally advanced EGFR mutation-positive non-small cell lung cancer. We encountered a case of a patient with diabetic nephropathy with lung adenocarcinoma treated with osimertinib, whose condition deteriorated from early nephropathy to end-stage renal disease in approximately 4 months. The patient had early diabetic nephropathy, but the use of a RTKI suppressed VEGF expression in podocytes, resulting in the induction of renal TMA and the development of rapidly progressive diabetic nephropathy.

Citric acid-based bicarbonate dialysate attenuates aortic arch calcification in maintenance hemodialysis patients: a retrospective observational study.

BACKGROUND: Progression of aortic calcification is associated with all-cause and cardiovascular mortality in hemodialysis patients. Blood calciprotein particle (CPP) levels are associated with coronary artery calcification and were reported to be inhibited when using citric acid-based bicarbonate dialysate (CD). Therefore, this study aimed to examine the effect of CD on the progression of the aortic arch calcification score (AoACS) and blood CPP levels in hemodialysis patients. METHODS: A 12-month retrospective observational study of 262 hemodialysis patients was conducted. AoACS was evaluated by calculating the number of calcifications in 16 segments of the aortic arch on chest X-ray (minimum score is 0; maximum score is 16 points). The patients were divided into the following groups according to their baseline AoACS: grade 0, AoACS = 0 points; grade 1, AoACS 1-4 points; grade 2, AoACS 5-8 points; grade 3, AoACS 9 points or higher. Patients on bisphosphonates or warfarin or with AoACS grade 3 were excluded. Progression, defined as ΔAoACS (12-month score - baseline score) > 0 points, was compared between the CD and acetic acid-based bicarbonate dialysate (AD) groups before and after adjusting the background using propensity score matching. RESULTS: The AoACS progression rate was significantly lower in the CD group than in the AD group (before matching: P = 0.020, after matching: P = 0.002). Multivariate logistic regression analysis showed that CD was significantly associated with AoACS progression (odds ratio 0.52, 95% confidence interval 0.29‒0.92, P = 0.025). CONCLUSION: CD may slow the progression of vascular calcification in hemodialysis patients.

Calciprotein particles regulate fibroblast growth factor-23 expression in osteoblasts.

Fibroblast growth factor-23 (FGF23) is a hormone indispensable for maintaining phosphate homeostasis. In response to phosphate intake, FGF23 is secreted from osteocytes/osteoblasts and acts on the kidney to increase urinary phosphate excretion. However, the mechanism by which these cells sense phosphate intake remains elusive. Calciprotein particles are nanoparticles of calcium-phosphate precipitates bound to serum protein fetuin-A and are generated spontaneously in solution containing calcium, phosphate, and fetuin-A to be dispersed as colloids. In cultured osteoblastic cells, increase in either calcium or phosphate concentration in the medium induced FGF23 expression, which was dependent on calciprotein particle formation. When transition of calcium-phosphate precipitates from the amorphous phase to the crystalline phase was blocked by bisphosphonate, the calciprotein particle size was reduced and FGF23 expression was augmented, suggesting that small calciprotein particles containing amorphous calcium-phosphate precipitates function as a more potent FGF23 inducer than larger calciprotein particles containing crystalline calcium-phosphate precipitates. In mice, bolus phosphate administration by oral gavage transiently increased circulating calciprotein particle levels followed by a modest increase in FGF23 expression and serum FGF23 levels. However, continuous dietary phosphate load induced robust and persistent increase in circulating calciprotein particles and FGF23 levels. We confirmed by in vivo imaging that calciprotein particles injected intravenously extravasated into the bone marrow and were deposited on the inner surface of the bone, indicating that these particles have direct access to osteoblasts. Thus, we propose that osteoblasts induce FGF23 expression and secretion when they sense an increase in extracellular calciprotein particles following phosphate ingestion.

Fibroblast growth factor 23 is upregulated in the kidney in a chronic kidney disease rat model.

The hormone fibroblast growth factor 23 (FGF23) is secreted from bone and is involved in phosphorus (P) metabolism. FGF23 mainly binds the FGF receptor, which interacts with αKlotho in the kidney or parathyroid and regulates Na-dependent phosphate co-transporter type IIa (NaPi-IIa) and type IIc (NaPi-IIc) expression, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) activity, and parathyroid hormone (PTH) secretion. In this study, we utilized hemi-nephrectomized rats fed a high-P diet (HP Nx), rats subjected to a partial nephrectomy (PN) and rats with doxorubicin-induced renal failure (DXR) as chronic kidney disease (CKD) animal models and analyzed the P metabolism and FGF23 expression in the kidneys in each CKD model. We cultured HK2 cells with a high level of P, 1,25(OH)2D3 or transforming growth factor-ß1 (TGFß1) to investigate the FGF23 expression mechanism. In both the HP Nx and PN rats, the blood FGF23 and PTH levels were increased. However, the 1,25(OH)2D3 level was increased in the HP Nx rats and decreased in the PN rats. In all three animal models, the mRNA expression of αKlotho, NaPi-IIa and NaPi-IIc was decreased, and the mRNA expression of TGFß1, collagen1a1, osteopontin and FGF23 was elevated in the kidney. FGF23 protein and mRNA were expressed at high levels in the extended tubule epithelium, which was an osteopontin-positive region in the HP and PN rats. FGF23 and osteopontin mRNAs were expressed in HK2 cells incubated with TGFß1; however, these levels were not altered in HK2 cells incubated with 1,25(OH)2D3 and high P levels in vitro. Altogether, FGF23 is expressed in the kidneys in CKD model rats. Following stimulation with TGFß1, the injured renal tubular epithelial cells are strongly suspected to express both FGF23 and osteopontin. FGF23 produced in the kidney might contribute to P metabolism in subjects with CKD.

Isotopomeric characterization of N2O produced, consumed, and emitted by automobiles.

Fossil fuel combustion is the second largest anthropogenic source of nitrous oxide (N2O) after agriculture. The estimated global N2O flux from combustion sources, as well as from other sources, still has a large uncertainty. Herein, we characterize automobile sources using N2O isotopomer ratios (nitrogen and oxygen isotope ratios and intramolecular site preference of 15N, SP) to assess their contributions to total global sources and to deconvolute complex production/consumption processes during combustion and subsequent catalytic treatments of exhaust. Car exhaust gases were sampled under running and idling state, and N2O isotopomer ratios were measured by mass spectrometry. The N2O directly emitted from an engine of a vehicle running at constant velocity had almost constant isotopomer ratios (delta15Nbulk = -28.7 +/- 1.2 per thousand, delta18O = 28.6 +/- 3.3 per thousand, and SP = 4.2 +/- 0.8 per thousand) irrespective of the velocity. After passing through catalytic converters, the isotopomer ratios showed an increase which varied with the temperature and the aging of the catalysts. The increase suggests that both production and consumption of N2O occur on the catalyst and that their rates can be comparable. It was noticed that in the idling state, the N2O emitted from a brand new car has higher isotopomer ratios than that from used cars, which indicate that technical improvements in catalytic converters can reduce the N2O from mobile combustion sources. On average, the isotopomeric signatures of N2O finally emitted from automobiles are not sensitive to running/idling states or to aging of the catalysts. Characteristic average isotopomer ratios of N2O from automobile sources are estimated at -4.9 +/- 8.2 per thousand, 43.5 +/- 13.9 per thousand, and 12.2 +/- 9.1 per thousand for delta15Nbulk, delta18O, and SP, respectively.

Hepatocyte growth factor gene transfer to alveolar septa for effective suppression of lung fibrosis.

We examined therapeutic gene transfer of human hepatocyte growth factor (hHGF) to alveolar septa in mouse bleomycin-induced lung fibrosis using macroaggregated albumin-polyethylenimine complex (MAA-PEI). Intravenous administration of MAA-PEI along with 1 microg pCAG.hHGF to C57BL/6 mice increased the uptake of plasmids into alveolar capillary endothelial cells and epithelial cells, prolonged hHGF expression in the lung, and induced a level of hHGF expression equal to that seen with 10 microg of hHGF-expression plasmids alone. The exogenous source of hHGF gene expression increased the endogenous mouse HGF in the lungs and significantly decreased TNF-alpha, IL-6, and collagen synthesis after bleomycin injury. Because GFP-labeled bone marrow-derived stem cells after bleomycin injury were reduced in number by HGF, the primary mechanism of HGF is likely to be the prevention of apoptosis, as has been suggested by in vitro experiments. This novel HGF gene transfer method to alveolar septa with nonstimulatory MAA-PEI conjugates may have promising clinical applications.