Bisphenol A (BPA) is a compound that is especially widespread in most commonly used objects due to its multiple uses in the plastic industry. However, several data support the need to restrict its use. In recent years, new implications of BPA on the renal system have been discovered, which denotes the need to expand studies in patients. To this end, a systematic review and a meta-analysis was performed to explore existing literature that examines the BPA-kidney disease paradigm and to determine what and how future studies will need to be carried out. Our systematic review revealed that only few relevant publications have focused on the problem. However, the subsequent meta-analysis revealed that high blood concentrations of BPA could be a factor in developing kidney disease, at least in people with previous pathologies such as diabetes or hypertension. Furthermore, BPA could also represent a risk factor in healthy people whose urinary excretion is higher. Finally, the data analyzed from the NHANES 03-16 cohort provided new evidence on the possible involvement of BPA in kidney disease. Therefore, our results underline the need to carry out a thorough and methodologically homogeneous study, delving into the relationship between urinary and blood BPA, glomerular filtration rate, and urine albumin-to-creatinine ratio, preferably in population groups at risk, and subsequently in the general population, to solve this relevant conundrum with critical potential implications in Public Health.

Phenols are uremic toxins of intestinal origin formed by bacteria during protein metabolism. Of these molecules, p-cresol is the most studied and has been associated with renal function impairment and vascular damage. Bisphenol A (BPA) is a molecule with structural similarity with phenols found in plastic food and beverage containers as well as in some dialyzers. BPA is considered an environmental toxicant based on animal and cell culture studies. Japanese authorities recently banned BPA use in baby bottles based on observational association studies in newborns. BPA is excreted in urine and uremic patients present higher serum levels, but there is insufficient evidence to set cut-off levels or to link BPA to any harmful effect in CKD. However, the renal elimination and potential exposure during dialysis warrant the monitoring of BPA exposure and the design of observational studies in which the potential health risks of BPA for end-stage renal disease patients are evaluated.

Bisphenol‐A, a chemical used in the production of the plastic lining of food and beverage containers, can be found in significant levels in human fluids. Recently, bisphenol‐A has been associated with low‐grade albuminuria in adults as well as in children. Since glomerular epithelial cells (podocytes) are commonly affected in proteinuric conditions, herein we explored the effects of bisphenol‐A on podocytes in vitro and in vivo. On cultured podocytes we first observed that bisphenol‐A—at low or high concentrations—(10 nM and 100 nM, respectively) was able to induce hypertrophy, diminish viability, and promote apoptosis. We also found an increase in the protein expression of TGF‐β1 and its receptor, the cyclin‐dependent kinase inhibitor p27Kip1, as well as collagen‐IV, while observing a diminished expression of the slit diaphragm proteins nephrin and podocin. Furthermore, mice intraperitoneally injected with bisphenol‐A (50 mg/Kg for 5 weeks) displayed an increase in urinary albumin excretion and endogenous creatinine clearance. Renal histology showed mesangial expansion. At ultrastructural level, podocytes displayed an enlargement of both cytoplasm and foot processes as well as the presence of condensed chromatin, suggesting apoptosis. Furthermore, immunohistochemistry for WT‐1 (specific podocyte marker) and the TUNEL technique showed podocytopenia as well as the presence of apoptosis, respectively. In conclusion, our data demonstrate that Bisphenol‐A exposure promotes a podocytopathy with proteinuria, glomerular hyperfiltration and podocytopenia. Further studies are needed to clarify the potential role of bisphenol‐A in the pathogenesis as well as in the progression of renal diseases. J. Cell. Physiol. 229: 2057–2066, 2014. © 2014 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.

Bisphenol A (BPA) is a widespread endocrine disruptor affecting many organs and systems. Previous work in our laboratory demonstrated that BPA could induce death due to necroptosis in murine aortic endothelial cells (MAECs). This work aims to evaluate the possible involvement of BPA-induced senescence mechanisms in endothelial cells. The β-Gal assays showed interesting differences in cell senescence at relatively low doses (100 nM and 5 µM). Western blots confirmed that proteins involved in senescence mechanisms, p16 and p21, were overexpressed in the presence of BPA. In addition, the UPR (unfolding protein response) system, which is part of the senescent phenotype, was also explored by Western blot and qPCR, confirming the involvement of the PERK-ATF4-CHOP pathway (related to pathological processes). The endothelium of mice treated with BPA showed an evident increase in the expression of the proteins p16, p21, and CHOP, confirming the results observed in cells. Our results demonstrate that oxidative stress induced by BPA leads to UPR activation and senescence since pretreatment with N-acetylcysteine (NAC) in BPA-treated cells reduced the percentage of senescent cells prevented the overexpression of proteins related to BPA-induced senescence and reduced the activation of the UPR system. The results suggest that BPA participates actively in accelerated cell aging mechanisms, affecting the vascular endothelium and promoting cardiovascular diseases.

Background. Hypertrophy of podocytes is characteristic in diabetic nephropathy (DN). Previously, we observed the upregulation of parathyroid hormone-related protein (PTHrP) and its receptor PTH1R, in experimental DN, associated with renal hypertrophy. Herein, we test the hypothesis that PTHrP participates in the mechanism of high glucose (HG)-induced podocyte hypertrophy. Methods. On mouse podocytes, hypertrophy was assessed by protein content/cell and [H³]leucine incorporation. Podocytes were stimulated with HG (25 mM), PTHrP(1–36) (100 nM), angiotensin II (AngII) (100 nM) or TGF-β₁ (5 ng/mL) in the presence or absence of PTHrP-neutralizing antibodies (α-PTHrP), the PTH1R antagonist JB4250 (10 μM), PTHrP silencer RNA (siRNA) or TGF-β₁ siRNA. Protein expression was analysed by western blot and immunohistochemistry. Results. HG-induced hypertrophy was abolished in the presence of either α-PTHrP or PTHrP siRNA. This effect was associated with an inhibition of the upregulation of TGF-β₁ and p27^Kip1. JB4250 also inhibited HG-induced p27^Kip1 upregulation. Interestingly, whilst HG and AngII were unable to stimulate the expression of p27^Kip1 on PTHrP siRNA-transfected podocytes, TGF-β₁ was still able to upregulate p27^Kip1 in these cells. Moreover, HG and PTHrP-induced hypertrophy as well as p27^Kip1 upregulation were abolished on TGF-β₁ siRNA-transfected podocytes. Furthermore, the glomeruli of transgenic PTHrP-overexpressing mice showed a constitutive overexpression of TGF-β₁ and p27^Kip1 to a degree similar to that of diabetic animals. Conclusions. PTHrP seems to participate in the hypertrophic signalling triggered by HG. In this condition, AngII induces the upregulation of PTHrP, which might induce the expression of TGF-β₁ and p27^Kip1. These findings provide new insights into the protective effects of AngII antagonists in DN, opening new paths for intervention.

Bisphenol A (BPA), a chemical -xenoestrogen- used in food containers is present in the urine of almost the entire population. Recently, several extensive population studies have proven a significant association between urinary excretion of BPA and albuminuria. The alteration of glomerular podocytes or "podocytopathy" is a common event in chronic albuminuric conditions. Since many podocytes recovered from patients' urine are viable, we hypothesized that BPA could impair podocyte adhesion capabilities. Using an in vitro adhesion assay, we observed that BPA impaired podocyte adhesion, an effect that was abrogated by Tamoxifen (an estrogen receptor blocker). Genomic and proteomic analyses revealed that BPA affected the expression of several podocyte cytoskeleton and adhesion proteins. Western blot and immunocytochemistry confirmed the alteration in the protein expression of tubulin, vimentin, podocin, cofilin-1, vinculin, E-cadherin, nephrin, VCAM-1, tenascin-C, and β-catenin. Moreover, we also found that BPA, while decreased podocyte nitric oxide production, it lead to overproduction of ion superoxide. In conclusion, our data show that BPA induced a novel type of podocytopathy characterizes by an impairment of podocyte adhesion, by altering the expression of adhesion and cytoskeleton proteins. Moreover, BPA diminished production of podocyte nitric oxide and induced the overproduction of oxygen-free metabolites. These data provide a mechanism by which BPA could participate in the pathogenesis and progression of renal diseases.