Clinical implementation of artificial-intelligence-assisted detection of breast cancer metastases in sentinel lymph nodes: the CONFIDENT-B single-center, non-randomized clinical trial.

Pathologists' assessment of sentinel lymph nodes (SNs) for breast cancer (BC) metastases is a treatment-guiding yet labor-intensive and costly task because of the performance of immunohistochemistry (IHC) in morphologically negative cases. This non-randomized, single-center clinical trial (International Standard Randomized Controlled Trial Number:14323711) assessed the efficacy of an artificial intelligence (AI)-assisted workflow for detecting BC metastases in SNs while maintaining diagnostic safety standards. From September 2022 to May 2023, 190 SN specimens were consecutively enrolled and allocated biweekly to the intervention arm (n = 100) or control arm (n = 90). In both arms, digital whole-slide images of hematoxylin-eosin sections of SN specimens were assessed by an expert pathologist, who was assisted by the 'Metastasis Detection' app (Visiopharm) in the intervention arm. Our primary endpoint showed a significantly reduced adjusted relative risk of IHC use (0.680, 95% confidence interval: 0.347-0.878) for AI-assisted pathologists, with subsequent cost savings of ~3,000 €. Secondary endpoints showed significant time reductions and up to 30% improved sensitivity for AI-assisted pathologists. This trial demonstrates the safety and potential for cost and time savings of AI assistance.

A Dutch consensus statement on the diagnosis and treatment of ANCA-associated vasculitis.

INTRODUCTION: Despite the availability of several guidelines on the diagnosis and treatment of antineutrophil cytoplasmic antibody-associated vasculitis (AAV), clinical routine practice will only improve when an implementation strategy is in place to support clinical decision making and adequate implementation of guidelines. We describe here an initiative to establish national and multidisciplinary consensus on broad aspects of the diagnosis and treatment of AAV relevant to daily clinical practice in the Netherlands. METHODS: A multidisciplinary working group of physicians in the Netherlands with expertise on AAV addressed the broad spectrum of diagnosis, terminology, and immunosuppressive and non-immunosuppressive treatment, including an algorithm for AAV patients. Based on recommendations from (inter)national guidelines, national consensus was established using a Delphi-based method during a conference in conjunction with a nationally distributed online consensus survey. Cut-off for consensus was 70% (dis)agreement. RESULTS: Ninety-eight professionals were involved in the Delphi procedure to assess consensus on 50 statements regarding diagnosis, treatment, and organisation of care for AAV patients. Consensus was achieved for 37/50 statements (74%) in different domains of diagnosis and treatment of AAV including consensus on the treatment algorithm for AAV. CONCLUSION: We present a national, multidisciplinary consensus on a diagnostic strategy and treatment algorithm for AAV patients as part of the implementation of (inter)national guideline-derived recommendations in the Netherlands. Future studies will focus on evaluating local implementation of treatment protocols for AAV, and assessments of current and future clinical practice variation in the care for AAV patients in the Netherlands.

Targeting multiple pathways reduces renal and cardiac fibrosis in rats with subtotal nephrectomy followed by coronary ligation.

AIM: Multiple interacting pathways contribute to progression of renal and cardiac damage in chronic kidney disease followed by chronic heart failure (renocardiac syndrome). We hypothesized that simultaneous pharmacological modulation of critical pathways implicated in renocardiac syndrome would effectively reduce fibrosis in and preserve function of heart and kidney. METHODS: Rats were subjected to subtotal nephrectomy followed 9 weeks later by coronary artery ligation. From week 11 until week 16, rats received vehicle or losartan, or a combination of the NF-kB inhibitor PDTC, the NO donor molsidomine and superoxide dismutase mimetic tempol, or a combination of all four of these plus metoprolol together. At week 16, renal and cardiac structure, function and gene expression were assessed. RESULTS: Individual and combined treatments were similarly effective in limiting cardiac fibrosis and further decline in systolic function. Combined treatment with all five drugs reduced renal fibrosis and CTGF gene expression more effectively than other strategies. Combining all five drugs reduced heart rate, inotropy and mean arterial pressure (MAP). CONCLUSION: Thus, in our model of chronic renocardiac syndrome, combined treatments similarly decreased cardiac fibrosis and stabilized systolic function as losartan alone, perhaps suggesting a dominant role for a single factor such as angiotensin II type 1 (AT1) receptor activation or inflammation in the network of aberrant systems in the heart. However, tubulointerstitial fibrosis was most effectively reduced by a five-drug regimen, pointing to additive effects of multiple pathophysiological pathways in the kidney.

Rapid hepatic clearance of full length CCN-2/CTGF: a putative role for LRP1-mediated endocytosis.

CCN-2 (connective tissue growth factor; CTGF) is a key factor in fibrosis. Plasma CCN-2 has biomarker potential in numerous fibrotic disorders, but it is unknown which pathophysiological factors determine plasma CCN-2 levels. The proteolytic amino-terminal fragment of CCN-2 is primarily eliminated by the kidney. Here, we investigated elimination and distribution profiles of full length CCN-2 by intravenous administration of recombinant CCN-2 to rodents. After bolus injection in mice, we observed a large initial distribution volume (454 mL/kg) and a fast initial clearance (120 mL/kg/min). Immunosorbent assay and immunostaining showed that CCN-2 distributed mainly to the liver and was taken up by hepatocytes. Steady state clearance in rats, determined by continuous infusion of CCN-2, was fast (45 mL/kg/min). Renal CCN-2 clearance, determined by arterial and renal vein sampling, accounted for only 12 % of total clearance. Co-infusion of CCN-2 with receptor-associated protein (RAP), an antagonist of LDL-receptor family proteins, showed that RAP prolonged CCN-2 half-life and completely prevented CCN-2 internalization by hepatocytes. This suggests that hepatic uptake of CCN-2 is mediated by a RAP-sensitive mechanism most likely involving LRP1, a member of the LDL-receptor family involved in hepatic clearance of various plasma proteins. Surface plasmon resonance binding studies confirmed that CCN-2 is an LRP1 ligand. Co-infusion of CCN-2 with an excess of the heparan sulphate-binding protamine lowered the large initial distribution volume of CCN-2 by 88 % and reduced interstitial staining of CCN-2, suggesting binding of CCN-2 to heparan sulphate proteoglycans (HSPGs). Protamine did not affect clearance rate, indicating that RAP-sensitive clearance of CCN-2 is HSPG independent. In conclusion, unlike its amino-terminal fragment which is cleared by the kidney, full length CCN-2 is primarily eliminated by the liver via a fast RAP-sensitive, probably LRP1-dependent pathway.

Release and pharmacokinetics of near-infrared labeled albumin from monodisperse poly(d,l-lactic-co-hydroxymethyl glycolic acid) microspheres after subcapsular renal injection.

Subcapsular renal injection is a novel administration method for local delivery of therapeutics for the treatment of kidney related diseases. The aim of this study was to investigate the feasibility of polymeric microspheres for sustained release of protein therapeutics in the kidney and study the subsequent redistribution of the released protein. For this purpose, monodisperse poly(d,l-lactic-co-hydroxymethyl glycolic acid) (PLHMGA) microspheres (40 µm in diameter) loaded with near-infrared dye-labeled bovine serum albumin (NIR-BSA) were prepared by a membrane emulsification method. Rats were injected with either free NIR-BSA or with NIR-BSA loaded microspheres (NIR-BSA-ms) and the pharmacokinetics of the released NIR-BSA was studied for 3 weeks by ex vivo imaging of organs and blood. Quantitative release data were obtained from kidney homogenates and possible metabolism of the protein was investigated by SDS-PAGE analysis of the samples. The ex vivo images showed a rapid decrease of the NIR signal within 24h in kidneys injected with free NIR-BSA, while, importantly, the signal of the labeled protein was still visible at day 21 in kidneys injected with NIR-BSA-ms. SDS-PAGE analysis of the kidney homogenates showed that intact NIR-BSA was released from the microspheres. The locally released NIR-BSA drained to the systemic circulation and subsequently accumulated in the liver, where it was degraded and excreted renally. The in vivo release of NIR-BSA was calculated after extracting the protein from the remaining microspheres in kidney homogenates. The in vivo release rate was faster (89 ± 4% of the loading in 2 weeks) compared to the in vitro release of NIR-BSA (38 ± 1% in 2 weeks). In conclusion, PLHMGA microspheres injected under the kidney capsule provide a local depot from which a formulated protein is released over a prolonged time-period.

Biocompatibility of poly(D,L-lactic-co-hydroxymethyl glycolic acid) microspheres after subcutaneous and subcapsular renal injection.

Poly(D,L-lactic-co-hydroxymethyl glycolic acid) (PLHMGA) is a biodegradable copolymer with potential as a novel carrier in polymeric drug delivery systems. In this study, the biocompatibility of PLHMGA microspheres (PLHMGA-ms) was investigated both in vitro in three different cell types (PK-84, HK-2 and PTECs) and in vivo at two implantation sites (by subcutaneous and subcapsular renal injection) in rats. Both monodisperse (narrow size distribution) and polydisperse PLHMGA-ms were prepared with volume weight mean diameter of 34 and 17 µm, respectively. Mono and polydisperse PLHMGA-ms showed good cytocompatibility properties upon 72 h incubation with the cells (100 µg microspheres/600 µL/cell line). A mild foreign body reaction was seen shortly after subcutaneous injection (20 mg per pocket) of both mono and polydisperse PLHMGA-ms with the presence of mainly macrophages, few foreign body giant cells and myofibroblasts. This transient inflammatory reaction diminished within 28 days after injection, the time-point at which the microspheres were degraded. The degradation profile is comparable to the in vitro degradation time of the microspheres (i.e., within 35 days) when incubated at 37 °C in phosphate buffered saline. Subcapsular renal injection of monodisperse PLHMGA-ms (10 mg) in rats was characterized with similar inflammatory patterns compared to the subcutaneous injection. No cortical damage was observed in the injected kidneys. In conclusion, this study demonstrates that PLHMGA-ms are well tolerated after in vivo injection in rats. This makes them a good candidate for controlled delivery systems of low-molecular weight drugs as well as protein biopharmaceuticals.

Compensatory enlargement of a solitary functioning kidney during fetal development.

OBJECTIVE: To determine the degree of compensatory enlargement, and its time of onset, of the solitary functioning kidney (SFK) in fetuses with unilateral renal agenesis (URA) or unilateral multicystic kidney dysplasia (MCKD). METHODS: This was a retrospective study of fetuses with URA or MCKD diagnosed prenatally and confirmed postnatally in the period from January 1999 to May 2011. Fetuses with any other congenital anomalies were excluded. Measurements of kidney length were retrieved from our prenatal ultrasound database and a nomogram was established and compared with that for normal kidney length. RESULTS: In total, 67 fetuses were identified, 60 with MCKD and seven with URA, for which we obtained 147 kidney length measurements from our database. Mean gestational age at time of measurement was 29.7 (range, 18.4-36.7) weeks. Compensatory enlargement, defined as renal length >95(th) percentile for gestational age, was demonstrated in 87% of the MCKD cases and 100% of the URA cases (88% of cases overall). We estimated the mean enlargement for an SFK (defined as difference from 50(th) percentile for normal renal length) at 36 weeks' gestation to be 23.1% (9.25 mm), with the mean value being 11.4% (5.04 mm) greater than the 95(th) percentile for a normal kidney at this gestational age. Compensatory enlargement of SFKs was evident from the 20(th) week of gestation onwards. CONCLUSION: Compensatory enlargement of SFKs occurs in almost 90% of fetuses with MCKD or URA, and may be observed from the 20(th) week of gestation onwards.

Size and volume charts of fetal kidney, renal pelvis and adrenal gland.

OBJECTIVE: To establish reference curves for size and volume of the fetal kidney, renal pelvis and adrenal gland, as measured using ultrasound from the 15(th) week of gestation. METHODS: This was a prospective, longitudinal study of 96 fetuses in low-risk singleton pregnancies, in which we performed serial ultrasound examinations at 4-week intervals. The length and anteroposterior and transverse diameters of both kidneys, the anteroposterior and transverse diameters of the renal pelvises and the length of the adrenal glands were measured three times at each examination, with the average being used for further analysis. Reference charts were constructed using multilevel statistical analysis and comparisons were made with previously published charts derived from cross-sectional data. RESULTS: We present nomograms for fetal kidney dimensions and volume, renal pelvis dimensions and adrenal gland length. The new charts show differences in shape and have narrower percentile bands in comparison to previously published reference ranges. CONCLUSIONS: These new charts of measurements of the fetal kidney, renal pelvis and adrenal gland, from a prospective, longitudinal study, may be useful in the diagnosis and assessment of pathology of the kidney and adrenal gland.

Local medial microenvironment directs phenotypic modulation of smooth muscle cells after experimental renal transplantation.

Smooth muscle cells (SMCs) play a key role in the pathogenesis of occlusive vascular diseases, including transplant vasculopathy. Neointimal SMCs in experimental renal transplant vasculopathy are graft-derived. We propose that neointimal SMCs in renal allografts are derived from the vascular media resulting from a transplantation-induced phenotypic switch. We examined the molecular changes in the medial microenvironment that lead to phenotypic modulation of SMCs in rat renal allograft arteries with neointimal lesions. Dark Agouti donor kidneys were transplanted into Wistar Furth recipients and recovered at day 56. Neointimal and medial layers were isolated using laser microdissection. Gene expression was analyzed using low-density arrays and confirmed by immunostaining. In allografts, neointimal SMCs expressed increased levels of Tgf ß1 and Pdgfb. In medial allograft SMCs, gene expression of Ctgf, Tgf ß1 and Pdgfrb was upregulated. Gene expression of Klf4 was upregulated as well, while expression of Sm22α was downregulated. Finally, PDGF-BB-stimulated phenotypically modulated SMCs, as evidenced by reduced contractile function in vitro which was accompanied by increased Klf4 and Col1α1, and reduced α-Sma and Sm22α expression. In transplant vasculopathy, neointimal PDGF-BB induces phenotypic modulation of medial SMCs, through upregulation of KLF4 in the media to contribute to (further) expansion of the neointima.

Transient nitric oxide reduction induces permanent cardiac systolic dysfunction and worsens kidney damage in rats with chronic kidney disease.

Left ventricular systolic dysfunction (LVSD) in patients with chronic kidney disease (CKD) is associated with poorer prognosis. Because patients with CKD often exhibit progressively decreased nitric oxide (NO) availability and inhibition of NO production can reduce cardiac output, we hypothesized that loss of NO availability in CKD contributes to pathogenesis of LVSD. Subtotally nephrectomized (SNX) rats were treated with a low dose of the NO synthase inhibitor N(omega)-nitro-L-arginine (L-NNA; 20 mg/l water; SNX+L-NNA) and compared with relevant control groups. To study permanent changes separate from hemodynamic effects, L-NNA was stopped after week 8 and rats were followed up to week 15, until blood pressure was similar in SNX+L-NNA and SNX groups. To study effects of NO depletion alone, a control group with high-dose L-NNA (L-NNA-High: 100 mg/l) was included. Mild systolic dysfunction developed at week 13 after SNX. In SNX+L-NNA, systolic function decreased by almost 50% already from week 4 onward, together with markedly reduced whole body NO production and high mortality. In L-NNA-High, LVSD was not as severe as in SNX+L-NNA, and renal function was not affected. Both LVSD and NO depletion were reversible in L-NNA-High after L-NNA was stopped, but both were persistently low in SNX+L-NNA. Proteinuria increased compared with rats with SNX, and glomerulosclerosis and cardiac fibrosis were worsened. We conclude that SNX+L-NNA induced accelerated and permanent LVSD that was functionally and structurally different from CKD or NO depletion alone. Availability of NO appears to play a pivotal role in maintaining cardiac function in CKD.

Connective tissue growth factor and cardiac fibrosis.

Cardiac fibrosis is a major pathogenic factor in a variety of cardiovascular diseases and refers to an excessive deposition of extracellular matrix components in the heart, which leads to cardiac dysfunction and eventually overt heart failure. Evidence is accumulating for a crucial role of connective tissue growth factor (CTGF) in fibrotic processes in several tissues including the heart. CTGF orchestrates the actions of important local factors evoking cardiac fibrosis. The central role of CTGF as a matricellular protein modulating the fibrotic process in cardiac remodelling makes it a possible biomarker for cardiac fibrosis and a potential candidate for therapeutic intervention to mitigate fibrosis in the heart.

Histological assessment of preimplantation biopsies may improve selection of kidneys from old donors after cardiac death.

Kidneys from old donors after cardiac death (DCD) may increase the donor pool but the prognosis of these kidneys is unsatisfactory. To improve these results, we retrospectively evaluated the diagnostic utility of published selection algorithms for old donor kidneys. We studied all DCD kidney transplantations between January 1, 1994 and July 1, 2005 at our institution (n = 199). Selection algorithms were evaluated in the subset of kidney transplantations from donors aged 60 years or older (n = 52). For histological assessment of kidney biopsies, glomerulosclerosis, tubular atrophy, interstitial fibrosis and vascular narrowing were blindly scored. Functional kidney weight was calculated as renal mass multiplied by the fraction of nonsclerosed glomeruli. Graft function and survival of kidneys from DCD aged 60 years or older were inferior to those from younger DCD. Histological scores were associated with kidney function and graft survival of old DCD kidney transplantations. Functional kidney weight was associated with kidney function but not graft survival, while donor glomerular filtration rate (GFR), donor age and machine perfusion characteristics were associated with neither of the clinical outcomes of interest. We conclude that histological assessment of preimplantation biopsies may improve the selection of kidneys from old DCD and may therefore contribute to expansion of the donor pool.

Focal segmental glomerulosclerosis in a patient homozygous for a CD2AP mutation.

Focal segmental glomerulosclerosis (FSGS) is a histologic diagnosis in several kidney diseases characterized by proteinuria and a severe decrease in kidney function. Mutations in several genes were found in patients with primary FSGS, one of which is a CD2-associated protein CD2AP (originally referred to as CMS). This gene encodes an adaptor protein that plays a role in endocytosis, cell motility, and cell survival. Mice deficient in Cd2ap (the mouse homolog) die due to kidney failure, while heterozygous mice develop lesions similar to those of FSGS patients. In the kidney, CD2AP regulates the actin cytoskeleton. The only previously described patient with CD2AP mutation had a severely truncated protein. In this study, we describe a patient with a novel mutation resulting in a premature stop codon yielding a protein truncated by only 4%. This shortened CD2AP protein displays a significantly decreased F-actin binding efficiency in vitro with no expression of the mutated allele in the patient's lymphocytes. Heterozygous expression of the CD2AP mutation in both parents did not lead to any kidney pathology, as both have normal glomerular filtration rates and no proteinuria.

Renal Fanconi syndrome with ultrastructural defects in lysinuric protein intolerance.

Renal Fanconi syndrome developed rapidly in a 3-year-old Moroccan girl with established lysinuric protein intolerance. She was hospitalized because of lowered consciousness, uncoordinated movements and hepatosplenomegaly after a febrile period. Laboratory investigations revealed plasma ammonia 270 micromol/L (normal <70 micromol/L), ferritin 159 micromol/L (normal 2-59 micromol/L), LDH 1180 U/L (normal 26-534 U/L). LPI was diagnosed based on the findings of reduced plasma ornithine, arginine and lysine, and an increased level of glutamine. Urinary orotic acid (645 micromol/mmol creatinine; normal <3.6) was strongly increased. A defect in the SLC7A7 amino acid transporter was established (homozygous c.726G > A mutation). Detailed renal function tests including an acid challenge test, bicarbonate loading, and tubular maximal reabsorption of glucose showed complex tubular dysfunction. No evidence of respiratory chain defects was found in muscle or kidney tissue. No morphological abnormalities were demonstrated in the mitochondria. Ultrastructural analysis of proximal tubular cells showed vacuolization and sloughing of the apical brush border (Fig. 1). Renal involvement in LPI has only been described in a few reports; however, no detailed studies of the renal acidification mechanism were performed. Our patient had evidence of a full-blown Fanconi syndrome. Surprisingly, a metabolic acidosis was found with a moderately increased serum anion gap combined with repeatedly normal plasma organic acid values. This finding is in contrast with the diagnosis of renal tubular acidosis. Patients with hyperlysinaemia have a similar heavy load on the renal tubules; they never develop a renal Fanconi syndrome. Therefore, we consider the intratubular accumulation of lysine an unlikely candidate for the development of the renal Fanconi syndrome.

Safety and efficacy of leflunomide in primary Sjögren's syndrome: a phase II pilot study.

BACKGROUND: For invalidating symptoms in primary Sjögren's syndrome (pSS), there is still a need for easy-to-administer, cost-effective and well-tolerated systemic treatment. Leflunomide (LEF) is structurally unrelated to other immunomodulatory drugs and might be efficacious in pSS, given its characteristic immunoregulatory modes of action. OBJECTIVE: To investigate the safety and efficacy of LEF in pSS in a phase II open-label pilot study. METHODS: 15 patients with pSS with early and active disease received LEF 20 mg once daily for 24 weeks. Tolerability, safety and efficacy of LEF were evaluated every 8 weeks. Additional safety visits were performed every fortnight. RESULTS: Mild gastrointestinal discomfort (including diarrhoea) and hair loss were mainly reported. Five patients developed lupus-like skin lesions on the face, arms or trunk, responding well to topical corticosteroids, nevertheless causing the withdrawal of one patient. Two patients with pre-existing hypertension had to increase dosages of anti-hypertensive drugs. Increased levels of alanine aminotransferase normalised after dose reduction in two patients. A decrease in general fatigue and an increase in physical functioning were observed after 24 weeks. Serum IgG levels decreased from 8 weeks onwards. Schirmer test values increased, not reaching statistical significance, whereas sialometry values did not change. In four of five repeated biopsies, the lymphocytic focus score decreased at the rate of 1 focus/4 mm(2). A remarkable amelioration of leucocytoclastic vasculitis was observed in three patients. CONCLUSIONS: Although the safety profile seems fairly acceptable, the observed indications for efficacy were modest and may be doubtful in justifying a randomised controlled trial of LEF in pSS.

Increased expression of heparanase in overt diabetic nephropathy.

In overt diabetic nephropathy (DNP), an increase in the permeability of the glomerular basement membrane (GBM) has been associated with a loss of negatively charged heparan sulfates (HS) in the GBM. Heparanase (HPSE), an endo-beta(1-4)-D-glucuronidase, can cleave HS and could be a potential candidate for the degradation of glomerular HS, leading to the development of proteinuria. We analyzed whether changes in HS expression are associated with HPSE expression in overt DNP. Immunofluorescence staining was performed to analyze HS, HPSE, and agrin core protein expression in kidney biopsies from patients with overt DNP and from rats and mice with streptozotocin (STZ)-induced diabetes. We also investigated the effect of transgenic HPSE overexpression in mice on glomerular HS and agrin expression. We demonstrate that the loss of GBM HS (-50%) and tubular HS (-60%) is associated with a four-fold increased HPSE expression in overt DNP. In addition, glomerular HPSE expression is upregulated in rats (messenger RNA (mRNA) 2.5-fold, protein three-fold) and mice (mRNA seven-fold, protein 1.5-fold) with STZ-induced diabetes. Furthermore, transgenic HPSE overexpression results in disappearance of HS, whereas expression of the core protein agrin remains unaltered. Our observations suggest that HPSE is involved in the pathogenesis of proteinuria in overt DNP by degradation of HS.

Albumin-bound fatty acids induce mitochondrial oxidant stress and impair antioxidant responses in proximal tubular cells.

Albumin induces oxidative stress and cytokine production in proximal tubular cells (PTECs). Albumin-bound fatty acids (FAs) enhance tubulopathic effects of albumin in vivo. We proposed that FA aggravation of albumin-induced oxidative stress in PTECs might be involved. We hypothesized that mitochondria could be a source of such stress. Using a fluorescent probe, we compared reactive oxygen species (ROS) production after exposure of PTECs to bovine serum albumin (BSA) alone or loaded with oleic acid (OA-BSA) (3-30 g/l for 2 h). There was no difference in cellular albumin uptake, but OA-BSA dose-dependently induced more ROS than BSA alone (P<0.001). OA-BSA-induced ROS was significantly alleviated by mitochondrial inhibition, but not by inhibitors of nicotinamide adenine dinucleotide phosphate hydrogenase (NADPH) oxidase, xanthine oxidase, or nitric oxide synthase. Gene expression analysis showed that neither the NADPH oxidase component p22phox nor xanthine oxidase was induced by BSA or OA-BSA. OA-BSA, in contrast to BSA, failed to induce mitochondrial manganese superoxide dismutase 2 (SOD2) expression. OA-BSA showed a greater capacity than BSA to downregulate heme oxygenase-1 mRNA expression and accentuate inflammatory cytokine mRNA and protein. Supplementation of SOD activity with EUK-8 reduced ROS, and interleukin-6 protein expression was suppressed by both mitochondrial inhibition and SOD augmentation. Thus, in PTECs, FAs accentuate albumin-induced oxidative stress and inflammatory cytokine expression via increased mitochondrial ROS, while frustrating protective antioxidant responses.

Bone morphogenetic protein-7 expression and activity in the human adult normal kidney is predominantly localized to the distal nephron.

Bone morphogenetic protein-7 (BMP)-7 plays an important role during fetal kidney development. In the adult, BMP-7 is most strongly expressed in the kidney compared to other organs, but the exact expression pattern as well as the function of BMP-7 is unclear. The major aim of the present study was to define which parts of the human kidney do physiologically express BMP-7 and which cells appear to be targets of BMP activity by showing phosphorylated BMP-receptor-associated Smads 1, 5, or 8 and inhibitor of differentiation factor 1 (ID1) expression. BMP-7 expression was localized by immunohistology to the epithelia of the distal tubule as well as the collecting ducts (CDs). Phospho-Smads 1/5/8 and ID1 expression largely colocalized with BMP-7 and was also localized in the epithelia of the distal tubule and the CDs. This was confirmed by polymerase chain reaction-based mRNA expression analysis. In vitro, proximal tubular cells (PTCs) expressed BMP receptors and BMP-receptor-associated Smads and were reactive to BMP-7. Our data indicate that BMP-7 expression in the adult human kidney appears to be more restricted than in the fetal situation and predominantly found in the distal nephron. Also, evidence of in vivo BMP signalling (i.e. phospho-Smads and ID1 expression) was found there. These findings suggest that BMP-7 plays a physiological role mostly in this part of the kidney. Still, as reported previously, PTCs are responsive to BMP-7, but presumably not in an autocrine or paracrine mode in normal adult kidneys.