Bisphenol A (BPA) and bisphenol F (BPF) are widely used to manufacture plastics and epoxy resins. Both compounds have been shown to be present in the environment and are food contaminants, with, as a ...result, a low but chronic exposure of humans. However, the fate and possible bioactivation of these compounds at the level of human cell lines was not completely elucidated yet. In this study, we investigated the ability of human cells (intestinal cell line: LS174T, hepatoma cell line: HepG2, and renal cell line: ACHN) to biotransform BPA and BPF, and focused on the cytotoxicity and genotoxicity of these two bisphenols, through the use of a novel and efficient genotoxic assay based on the detection of histone H2AX phosphorylation. BPA and BPF were extensively metabolized in HepG2 and LS174T cell lines, with stronger biotransformation capabilities in intestinal cells than observed in liver cells. Both cell lines produced the glucuronide as well as the sulfate conjugates of BPA. Conversely, the ACHN cell line was found to be devoid of any metabolic capabilities for the two examined bisphenols. Cytotoxicity was tested for BPA, BPF, as well as one metabolite of BPF produced in vivo in rat, namely dihydroxybenzophenone (DHB). In the three cell lines used, we observed similar ranges of toxicity, with DHB being weakly cytotoxic, BPF exhibiting an intermediary cytotoxicity, and BPA being the most cytotoxic compound tested. BPA and DHB were not found to be genotoxic, whatever the cell line examined. BPF was clearly genotoxic in HepG2 cells. These results demonstrate that some human cell lines extensively metabolize bisphenols and establish the genotoxic potential of bisphenol F.
Focal segmental glomerulosclerosis (FSGS) is a glomerular disease characterized by proteinuria, frequent progression to end‐stage renal disease, and recurrence after kidney transplantation in ∼25% of ...patients, which negatively impacts long‐term allograft survival. Experimental studies suggest that abnormalities in T and, possibly, B cells may represent one initial pathogenic trigger, leading to podocyte injury and progressive loss. New data also support the existence of circulating permeability factors able to damage the podocytes, but no single molecule has been consistently identified as the causal pathogenic element in FSGS recurrence. Unfortunately, major progress from mechanistic studies has not translated into substantial advancements in patient treatment, with plasmapheresis (PP) and high doses of cyclosporine (CsA) remaining the mainstays of therapy. Despite consistent experimental and clinical evidence that treatment of proteinuria slows renal function decline in proteinuric nephropathies, maximal use of antiproteinuric agents such as renin angiotensin system antagonists is not routine in the management of FSGS recurrence. More recently, encouraging results have been reported with anti‐CD20 depleting antibody rituximab, but further studies are needed to establish its safety/efficacy profile.
The authors review recent advancements in understanding the pathophysiology of focal segmental glomerulosclerosis (FSGS) recurrence after kidney transplant and critically discuss the current therapeutic options.
The development of
in vitro genotoxic assays as an alternative method to animal experimentation is of growing interest in the context of the implementation of new regulations on chemicals. However, ...extrapolation of toxicity data from
in vitro systems to
in vivo models is hampered by the fact that
in vitro systems vary in their capability to metabolize chemicals, and that biotransformation can greatly influence the experimental results. Therefore, much attention has to be paid to the cellular models used and experimental conditions. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic ubiquitous pollutants. Human exposure to PAHs is mainly from food origin. In this study, a detailed analysis of the biotransformation capabilities of three human cell lines commonly used for
in vitro testing (HepG2, ACHN and Caco-2) was undertaken using 3 model PAHs (benzo(
a)pyrene B(
a)P, fluoranthene FLA and 3-methylcholanthrene 3-MC). Concomitantly the genotoxicity of these PAHs was investigated in different cell lines, using a new genotoxic assay (H2AX) in 96-well plates. The metabolic rates of B(
a)P, FLA and 3-MC were similar in HepG2 and Caco-2 cell lines, respectively, though with the production of different metabolites. The ACHN cell line was shown to express very limited metabolic capabilities. We demonstrated that the PAHs having a high metabolic rate (B(
a)P and 3-MC) were genotoxic from 10
−7 molar in both HepG2 and Caco-2 cells. The present study shows that H2AX measurement in human cell lines competent for the metabolism, is an efficient and sensitive genotoxic assay requiring less cells and time than other currently available tests.
Polycyclic Aromatic Hydrocarbons (PAHs) constitute a family of over one hundred compounds and can generally be found in complex mixtures. PAHs metabolites cause DNA damage which can lead to the ...development of carcinogenesis. Toxicity assessment of PAH complex mixtures is currently expressed in terms of toxic equivalents, based on Toxicity Equivalent Factors (TEFs). However, the definition of new TEFs for a large number of PAH could overcome some limitations of the current method and improve cancer risk assessment. The current investigation aimed at deriving the relative potency factors of PAHs, based on their genotoxic effect measured in vitro and analyzed with mathematical models. For this purpose, we used a new genotoxic assay (γH2AX) with two human cell lines (HepG2 and LS-174T) to analyze the genotoxic properties of 13 selected PAHs at low doses after 24h treatment. The dose–response for genotoxic effects was modeled with a Hill model; equivalency between PAHs at low dose was assessed by applying constraints to the model parameters. In the two cell lines tested, we observed a clear dose–response for genotoxic effects for 11 tested compounds. LS-174T was on average ten times more sensitive than HepG2 towards PAHs regarding genotoxicity. We developed new TEFs, which we named Genotoxic Equivalent Factor (GEF). Calculated GEF for the tested PAHs were generally higher than the TEF usually used. Our study proposed a new in vitro based method for the establishment of relevant TEFs for PAHs to improve cancer risk assessment.
► Examination of the genotoxic properties of 13 PAHs on two human cell lines. ► Modelization with a Hill model of the genotoxic dose–response. ► First investigation of the genotoxicity of benzocfluorene on human cell lines. ► Establishment of relevant TEFs for PAHs to improve cancer risk assessment.
Disposition of fipronil in rats Cravedi, J.P.; Delous, G.; Zalko, D. ...
Chemosphere (Oxford),
11/2013, Letnik:
93, Številka:
10
Journal Article
Recenzirano
•We analyzed the tissue distribution and the biotransformation of fipronil in rats.•After a single oral dose, the highest residue levels were found in adipose tissue and to a lesser extent in ...adrenals.•Residues corresponded to fipronil sulfone.•Several other metabolites were identified in excreta, mainly glucuronide and sulfate conjugates.
In the scientific literature, little attention has been paid to the disposition of fipronil, a phenyl pyrazole insecticide. In this study, the tissue distribution, the metabolic fate, and the elimination of fipronil was investigated in rats using radiolabeled fipronil. When a single oral dose of 14C-fipronil (10mgkg−1 b.w.) was given to rats, the proportion of dose eliminated in urine and feces 72h after dosing was ca 4% for each route. At the end of the experiment the highest levels of radioactivity were found in adipose tissue and adrenals.
The main part of the radioactivity present in investigated tissues (adipose tissue, adrenals, liver, kidney, testes) was due to fipronil-sulfone. Five additional metabolites, isolated from urine were characterized by LC-MS/MS. Most of them are formed by the loss of the trifluoromethylsulphinyl group and subsequent hydroxylation and/or conjugation to glucuronic acid or sulfate.
In conclusion, the retention of the metabolite fipronil sulfone in tissues following fipronil administration raises the question of the potential toxicity of this insecticide.
The efficiency with which a nanofiltration membrane (Desal 5 DK) removes bisphenol A (BPA) was investigated, together with the mechanisms involved. Whereas high retention (>90%) was obtained at the ...beginning of the filtration, the observed retention coefficient (
R
obs) decreased to around 50% when the membrane became saturated, due to adsorption of BPA onto the membrane structure. The presence of ions (Na
+, Cl
−) affects the
R
obs, this effect being attributed to a change in BPA hydrodynamic radius. Moreover, in our operating conditions, the presence of natural organic matter (1
mg/L) in the feed solution does not lead to variation in BPA retention at steady state.
Emerging evidence indicates that complement provides costimulatory signals for murine T cells but whether complement impacts human T cells remains unclear. We observed production of complement ...activation products C3a and C5a during in vitro cultures of human T cells responding to allogeneic dendritic cells (DC). Both partners expressed the receptors for C3a (C3aR) and C5a (C5aR) and C3aR‐ and C5aR‐antagonists inhibited T cell proliferation. Recombinant C3a/C5a promoted CD4+ T cell expansion, bypassed the inhibitory effects of CTLA4‐Ig, and induced AKT phosphorylation, the latter biochemically linking C3aR/C5aR to known T cell signaling pathways. Lowering DC C3a/C5a production by siRNA knockdown of DC C3 reduced T cell alloresponses. Conversely downregulating DC expression of the complement regulatory protein decay–accelerating factor increased immune cell C3a/C5a and augmented T cell proliferation, identifying antigen presenting cells as the dominant complement source. Pharmacological C5aR blockade reduced graft versus host disease (GVHD) scores, prolonged survival, and inhibited T cell responses in NOD scid γcnull mouse recipients of human peripheral blood mononuclear cells, verifying that the mechanisms apply in vivo. Together our findings unequivocally document that immune cell–derived complement impacts human T cell immunity and provide the foundation for future studies targeting C3aR/C5aR as treatments of GVHD and organ transplant rejection in humans.
This study shows that APC‐derived C3a and C5a transmit costimulatory, proliferative signals upon ligating their receptors expressed on human alloreactive CD4 T cells, and that pharmacological C5a receptor blockade reduces human, T cell‐mediated, xenogeneic graft versus host disease in vivo.
Pretransplant donor biopsy (PTDB)‐based marginal donor allocation systems to single or dual renal transplantation could increase the use of organs with Kidney Donor Profile Index (KDPI) in the ...highest range (e.g. >80 or >90), whose discard rate approximates 50% in the United States. To test this hypothesis, we retrospectively calculated the KDPI and analyzed the outcomes of 442 marginal kidney transplants (340 single transplants: 278 with a PTDB Remuzzi score <4 median KDPI: 87; interquartile range (IQR): 78–94 and 62 with a score = 4 median KDPI: 87; IQR: 76–93; 102 dual transplants median KDPI: 93; IQR: 86–96) and 248 single standard transplant controls (median KDPI: 36; IQR: 18–51). PTDB‐based allocation of marginal grafts led to a limited discard rate of 15% for kidneys with KDPI of 80–90 and of 37% for kidneys with a KDPI of 91–100. Although 1‐year estimated GFRs were significantly lower in recipients of marginal kidneys (−9.3, −17.9 and −18.8 mL/min, for dual transplants, single kidneys with PTDB score <4 and =4, respectively; p < 0.001), graft survival (median follow‐up 3.3 years) was similar between marginal and standard kidney transplants (hazard ratio: 1.20 95% confidence interval: 0.80–1.79; p = 0.38). In conclusion, PTDB‐based allocation allows the safe transplantation of kidneys with KDPI in the highest range that may otherwise be discarded.
This study shows that the standardized assessment of formalin‐fixed pretransplant biopsies helps recover donors with KDPI in the highest range that would be otherwise discarded, and by providing the expected graft outcomes based on KDPI and pretransplant biopsy, it guides the clinician facing the difficult decision whether to accept or reject these organs. See editorial by Gupta et al on page 2444.
The present study was conducted to determine whether exposure to the mono-(2-ethylhexyl) phthalate (MEHP) represents a genuine threat to male human reproductive function. To this aim, we investigated ...the effects on human male fetal germ cells of a 10−5M exposure. This dose is slightly above the mean concentrations found in human fetal cord blood samples by biomonitoring studies. The in vitro experimental approach was further validated for phthalate toxicity assessment by comparing the effects of in vitro and in vivo exposure in mouse testes.
Human fetal testes were recovered during the first trimester (7–12weeks) of gestation and cultured in the presence or not of 10−5M MEHP for three days. Apoptosis was quantified by measuring the percentage of Caspase-3 positive germ cells. The concentration of phthalate reaching the fetal gonads was determined by radioactivity measurements, after incubations with 14C-MEHP.
A 10−5M exposure significantly increased the rate of apoptosis in human male fetal germ cells. The intratesticular MEHP concentration measured corresponded to the concentration added in vitro to the culture medium. Furthermore, a comparable effect on germ cell apoptosis in mouse fetal testes was induced both in vitro and in vivo.
This study suggests that this 10−5M exposure is sufficient to induce changes to the in vivo development of the human fetal male germ cells.
► 10−5M of MEHP impairs germ cell development in the human fetal testis. ► Organotypic culture is a suitable approach to investigate phthalate effects in human. ► MEHP is not metabolized in the human fetal testis. ► In mice, MEHP triggers similar effects both in vivo and in vitro.
•We examined the genotoxic potential of 27 HAPs.•Genotoxicity was evaluated with the γH2AX assay and was modelled with the Hill equation.•We developed for each compound, in each cell line, Genotoxic ...Equivalent Factor.•These new equivalent factor for PAHs may improve cancer risk assessment.
Polycyclic Aromatic Hydrocarbons (PAHs) form a family of compounds that are generally found in complex mixtures. PAHs can lead to the development of carcinogenesis. The Toxicity Equivalent Factor (TEF) approach has been suggested for estimating the toxicity of PAHs, however, due to the relative weakness of available data, TEF have not been applied for the risk characterization of PAHs as food contaminants in Europe. The determination of new TEFs for a large number of PAHs could overcome some limitations of the current method and improve cancer risk assessment. The present investigation aimed at deriving new TEFs for PAHs, based on their genotoxic effect measured in vitro and analyzed with mathematical models. For this purpose, we used a genotoxicity assay (γH2AX) with three human cell lines to analyze the genotoxic properties of 27 selected PAHs after 24 h treatment. For 11 compounds, we did not detect any genotoxic potential. For the remaining 16 PAHs, the concentration-response for genotoxic effect was modelled with the Hill equation; equivalency between PAHs at low dose was assessed by applying constraints to the model parameters. We developed for each compound, in each cell line, Genotoxic Equivalent Factor (GEF). Calculated GEF for the tested PAHs were similar in all cell lines and generally higher than the TEF usually used. These new equivalent factors for PAHs should improve cancer risk assessment.
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