Microbial metabolism of L-tyrosine protects against allergic airway inflammation.

The constituents of the gut microbiome are determined by the local habitat, which itself is shaped by immunological pressures, such as mucosal IgA. Using a mouse model of restricted antibody repertoire, we identified a role for antibody-microbe interactions in shaping a community of bacteria with an enhanced capacity to metabolize L-tyrosine. This model led to increased concentrations of p-cresol sulfate (PCS), which protected the host against allergic airway inflammation. PCS selectively reduced CCL20 production by airway epithelial cells due to an uncoupling of epidermal growth factor receptor (EGFR) and Toll-like receptor 4 (TLR4) signaling. Together, these data reveal a gut microbe-derived metabolite pathway that acts distally on the airway epithelium to reduce allergic airway responses, such as those underpinning asthma.

Metabolic Communication by SGLT2 Inhibition.

BACKGROUND: SGLT2 (sodium-glucose cotransporter 2) inhibitors (SGLT2i) can protect the kidneys and heart, but the underlying mechanism remains poorly understood. METHODS: To gain insights on primary effects of SGLT2i that are not confounded by pathophysiologic processes or are secondary to improvement by SGLT2i, we performed an in-depth proteomics, phosphoproteomics, and metabolomics analysis by integrating signatures from multiple metabolic organs and body fluids after 1 week of SGLT2i treatment of nondiabetic as well as diabetic mice with early and uncomplicated hyperglycemia. RESULTS: Kidneys of nondiabetic mice reacted most strongly to SGLT2i in terms of proteomic reconfiguration, including evidence for less early proximal tubule glucotoxicity and a broad downregulation of the apical uptake transport machinery (including sodium, glucose, urate, purine bases, and amino acids), supported by mouse and human SGLT2 interactome studies. SGLT2i affected heart and liver signaling, but more reactive organs included the white adipose tissue, showing more lipolysis, and, particularly, the gut microbiome, with a lower relative abundance of bacteria taxa capable of fermenting phenylalanine and tryptophan to cardiovascular uremic toxins, resulting in lower plasma levels of these compounds (including p-cresol sulfate). SGLT2i was detectable in murine stool samples and its addition to human stool microbiota fermentation recapitulated some murine microbiome findings, suggesting direct inhibition of fermentation of aromatic amino acids and tryptophan. In mice lacking SGLT2 and in patients with decompensated heart failure or diabetes, the SGLT2i likewise reduced circulating p-cresol sulfate, and p-cresol impaired contractility and rhythm in human induced pluripotent stem cell-derived engineered heart tissue. CONCLUSIONS: SGLT2i reduced microbiome formation of uremic toxins such as p-cresol sulfate and thereby their body exposure and need for renal detoxification, which, combined with direct kidney effects of SGLT2i, including less proximal tubule glucotoxicity and a broad downregulation of apical transporters (including sodium, amino acid, and urate uptake), provides a metabolic foundation for kidney and cardiovascular protection.

Clofoctol inhibits SARS-CoV-2 replication and reduces lung pathology in mice.

Drug repurposing has the advantage of shortening regulatory preclinical development steps. Here, we screened a library of drug compounds, already registered in one or several geographical areas, to identify those exhibiting antiviral activity against SARS-CoV-2 with relevant potency. Of the 1,942 compounds tested, 21 exhibited a substantial antiviral activity in Vero-81 cells. Among them, clofoctol, an antibacterial drug used for the treatment of bacterial respiratory tract infections, was further investigated due to its favorable safety profile and pharmacokinetic properties. Notably, the peak concentration of clofoctol that can be achieved in human lungs is more than 20 times higher than its IC50 measured against SARS-CoV-2 in human pulmonary cells. This compound inhibits SARS-CoV-2 at a post-entry step. Lastly, therapeutic treatment of human ACE2 receptor transgenic mice decreased viral load, reduced inflammatory gene expression and lowered pulmonary pathology. Altogether, these data strongly support clofoctol as a therapeutic candidate for the treatment of COVID-19 patients.

Severe 25E-NBOH intoxication associated with MDPHP intake: a case report, metabolism study, and literature review.

N-Benzylphenethylamine derivatives are 5-HT2A receptor agonists with hallucinogenic properties, including NBOMe (N-(2-methoxybenzyl)-2-(3,4,5-trimethoxyphenyl)ethan-1-amine) and NBOH (2-(((2,5-dimethoxyphenethyl)amino)methyl)phenol). We reported here the case of a 23-year-old man who presented a serotoninergic syndrome and a loss of consciousness following the consumption of a powder labelled as 25I-NBOH. Toxicological analyses of biological samples were carried out using a liquid chromatography high-resolution mass spectrometry. Two new psychoactive substances were identified and confirmed with certified reference materials: 25E-NBOH (2-(((4-ethyl-2,5-dimethoxyphenethyl)amino)methyl)phenol) and MDPHP (1-(benzo[d][1,3]dioxol-5-yl)-2-(pyrrolidin-1-yl)hexan-1-one). Pharmaceuticals administered to the patient during his medical care were found in plasma and urine. 25E-NBOH and MDPHP concentrations were respectively at 2.3 ng/mL and 3.4 ng/mL in plasma, and 25.7 ng/mL and 30.5 ng/mL in urine. 25I-NBOH (2-(((4-iodo-2,5-dimethoxyphenethyl)amino)methyl)phenol) was specifically searched in both samples and was not detected. These results are discussed along with a literature review on human cases of exposure to N-benzylphenethylamine derivatives. Using molecular networking approach, we propose the first 25E-NBOH metabolism study using authentic biological samples (plasma and urine). We described seven metabolites (M1 to M7), including two phase I (m/z 330.172; m/z 288.160) and five phase II metabolites (m/z 464.191, m/z 478.207, m/z 492.223, m/z 508.218; m/z 396.156). The M6 (m/z 492.223) was the most intense ion detected in plasma and urine and could be proposed as a relevant 25E-NBOH consumption marker. Overall, we described an original case of 25E-NBOH poisoning and identified metabolites that could potentially be used as consumption markers to detect 25E-NBOH intoxications with a higher confidence level and probably a longer detection window.

Dicopper Complexes of p-Cresol-2,6-bis(amide-tether-dpa4-X) (X = MeO and Cl): Selective ROS Generation and Cytotoxicity Enhancement Controlled by Electronic and Hydrophobic Effects of the MeO and Cl Groups.

Two new p-cresol-2,6-bis(amide-tether-dpa4-X) ligands (HL4-X, X = MeO and Cl) and their dicopper complexes [Cu2(µ-1,1-OAc)(µ-1,3-OAc)(L4-MeO)]Y (Y = PF6 1a, OAc 1b) and [Cu2(µ-1,3-OAc)2(L4-Cl)]Y (Y = ClO4 2a, OAc 2b) were synthesized. The electronic and hydrophobic effects of the MeO and Cl groups were examined compared with nonsubstituted complex [Cu2(µ-1,1-OAc)(µ-1,3-OAc)(L)]+ (3). The electronic effects were found in crystal structures, spectroscopic characterization, and redox potentials of these complexes. 1b and 2b were reduced to Cu(I)Cu(I) with sodium ascorbate and reductively activated O2 to produce H2O2 and HO•. The H2O2 release and HO• generation are promoted by the electronic effects. The hydrophobic effects increased the lipophilicity of 1b and 2b. Cellular ROS generation of 1b, 2b, and 3 was visualized by DCFH-DA. To examine the intracellular behavior, boron dipyrromethene (Bodipy)-modified complexes 4B and 5B corresponding to 1b and 2b were synthesized. These support that 1b and 2b are localized at the ER and Golgi apparatus. The cytotoxicity of 1b and 2b against various cell lines was examined by MTT assay. 1b and 2b were 7- and 41-fold more cytotoxic than 3. 1b generated ROS selectively in cancer cell but 2b nonselectively in cancer and normal cells, causing cancer- and normal-cell-selective cytotoxicity, respectively.

Constructing 3D flower-like S-scheme N-Bi2O2CO3/g-C3N4 heterojunction with enhanced photocatalytic performance.

Mineral processing wastewater contains a lot of organic matter and heavy metal ions, and poor self-degradation ability makes it a key treatment object in environmental treatment. Photocatalysis is a promising technology to efficiently mineralize refractory contaminants from wastewater. In this work, 3D flower-like S-scheme N-Bi2O2CO3/g-C3N4 heterostructures were successfully constructed by hydrothermal method with the auxiliary of ionic liquids. The photocatalytic experiments show that the catalytic activity of heterojunction photocatalysts was significantly higher than that of bare g-C3N4 and N-Bi2O2CO3 for the degradation of two pollutants. NBOC/CN-2 shows the highest photocatalytic performance, and the degradation efficiency of sodium isobutyl xanthate (SIBX) on NBOC/CN-2 is 1.85 and 3 times that of bare g-C3N4 and Bi2O2CO3, respectively. The degradation efficiency of m-Cresol on NBOC/CN-2 is 8.34 and 6.93 times that of bare g-C3N4 and N-Bi2O2CO3, respectively. This significantly enhanced photocatalytic activity is attributed to the formation of flower-like heterojunctions, which can greatly increase the specific surface area and facilitate the separation and migration of photogenerated carriers. Total organic carbon (TOC) experiment proves that the two pollutants are effectively mineralized under the action of the prepared photocatalyst. The degradation path of m-Cresol degradation products was inferred based on the ion fragments. The capture experiment and Nitro-blue tetrazolium (NBT)-•O2- measurement show that superoxide radical plays a major role in photocatalytic degradation. The outstanding stability of the prepared flower-like heterojunction samples was examined by cyclic experiments. The S-scheme charge transfer mechanism has been proposed to explain the boosted activity of the flower-like heterojunction photocatalyst. This work provides a new idea for the design of efficient and stable g-C3N4-based photocatalyst for the photocatalytic degradation of refractory wastewater.

Impact of plastic-related compounds on the gene expression signature of HepG2 cells transfected with CYP3A4.

The presence of plastic and microplastic within the oceans as well as in marine flora and fauna have caused a multitude of problems that have been the topic of numerous investigations for many years. However, their impact on human health remains largely unknown. Such plastic and microplastic particles have been detected in blood and placenta, underlining their ability to enter the human body. Plastics also contain other compounds, such as plasticizers, antioxidants, or dyes, whose impact on human health is currently being studied. Critical enzymes within the metabolism of endogenous molecules, especially of xenobiotics, are the cytochrome P450 monooxygenases (CYPs). Although their importance in maintaining cellular balance has been confirmed, their interactions with plastics and related products are poorly understood. In this study, the possible relationship between different plastic-related compounds and CYP3A4 as one of the most important CYPs was analyzed using hepatic cells overexpressing this enzyme. Beginning with virtual compound screening and molecular docking of more than 1000 plastic-related compounds, several candidates were identified to interact with CYP3A4. In a second step, RNA-sequencing was used to study in detail the transcriptome-wide gene expression levels affected by the selected compounds. Three candidate molecules ((2,2'-methylenebis(6-tert-butyl-4-methylphenol), 1,1-bis(3,5-di-tert-butyl-2-hydroxyphenyl)ethane, and 2,2'-methylenebis(6-cyclohexyl-4-methylphenol)) had an excellent binding affinity to CYP3A4 in-silico as well as cytotoxic effects and interactions with several metabolic pathways in-vitro. We identified common pathways influenced by all three selected plastic-related compounds. In particular, the suppression of pathways related to mitosis and 'DNA-templated DNA replication' which were confirmed by cell cycle analysis and single-cell gel electrophoresis. Furthermore, several mis-regulated metabolic and inflammation-related pathways were identified, suggesting the induction of hepatotoxicity at different levels. These findings imply that these compounds may cause liver problems subsequently affecting the entire organism.

Suitability of different reconstructed human skin models in the skin and liver Chip2 microphysiological model to investigate the kinetics and first-pass skin metabolism of the hair dye, 4-amino-2-hydroxytoluene.

The HUMIMIC skin-liver Chip2 microphysiological systems model using the epidermal model, EpiDerm™, was reported previously to mimic application route-dependent metabolism of the hair dye, 4-amino-2-hydroxytoluene (AHT). Therefore, we evaluated the use of alternative skin models-SkinEthic™, EpiDermFT™ and PhenionFT™-for the same purpose. In static incubations, AHT permeation was similar using SkinEthic™ and EpiDerm™ models. Older Day 21 (D21) SkinEthic™ models with a thicker stratum corneum did not exhibit a greater barrier to AHT (overall permeation was the same in D17 and D21 models). All epidermal models metabolised AHT, with the EpiDerm™ exhibiting higher N-acetylation than SkinEthic™ models. AHT metabolism by D21 SkinEthic™ models was lower than that by D17 SkinEthic™ and EpiDerm™ models, thus a thicker stratum corneum was associated with fewer viable cells and a lower metabolic activity. AHT permeation was much slower using PhenionFT™ compared to epidermal models and better reflected permeation of AHT through native human skin. This model also extensively metabolised AHT to N-acetyl-AHT. After a single topical or systemic application of AHT to Chip2 model with PhenionFT™, medium was analysed for parent and metabolites over 5 days. The first-pass metabolism of AHT was demonstrated, and the introduction of a wash step after 30 min decreased the exposure to AHT and its metabolites by 33% and 40%-43%, respectively. In conclusion, epidermal and FT skin models used in the Chip2 can mimic the first-pass skin metabolism of AHT. This highlights the flexibility of the Chip2 to incorporate different skin models according to the purpose.

How renal toxins respond to renal function deterioration and oral toxic adsorbent in pH-controlled releasing capsule.

The number of patients with chronic kidney disease (CKD) is increasing. Oral toxin adsorbents may provide some value. Several uremic toxins, including indoxyl sulfate (IS), p-cresol (PCS), acrolein, per- and poly-fluoroalkyl substances (PFAS), and inflammation markers (interleukin 6 [IL-6] and tumor necrosis factor [TNF]-alpha) have been shown to be related to CKD progression. A total of 81 patients taking oral activated charcoal toxin adsorbents (AC-134), which were embedded in capsules that dissolved in the terminal ileum, three times a day for 1 month, were recruited. The renal function, hemoglobulin (Hb), inflammation markers, three PFAS (PFOA, PFOS, and PFNA), and acrolein were quantified. Compared with the baseline, an improved glomerular filtration rate (GFR) and significantly lower acrolein were noted. Furthermore, the CKD stage 4 and 5 group had significantly higher concentrations of IS, PCS, IL-6, and TNF but lower levels of Hb and PFAS compared with the CKD Stage 3 group at baseline and after the intervention. Hb was increased only in the CKD Stage 3 group after the trial (p = .032). Acrolein did not differ between the different CKD stage groups. Patients with improved GFR (responders) (about 77%) and nonresponders had similar baseline GFR. Responders had higher acrolein and PFOA levels throughout the study and a more significant reduction in acrolein, indicating a better digestion function. Both the higher PFOA and lower acrolein may be related to improved eGFR (and possibly to improvements in proteinuria, which we did not measure. Proteinuria is associated with PFAS loss in the urine), AC-134 showed the potential to improve the GFR and decrease acrolein, which might better indicate renal function change. Future studies are needed with longer follow-ups.

Hemodiafiltration with endogenous reinfusion for uremic toxin removal in patients undergoing maintenance hemodialysis: a pilot study.

OBJECTIVE: To delineate the efficacy and safety profile of hemodiafiltration with endogenous reinfusion (HFR) for uremic toxin removal in patients undergoing maintenance hemodialysis (MHD). METHODS: Patients who have been on MHD for a period of at least 3 months were enrolled. Each subject underwent one HFR and one hemodiafiltration (HDF) treatment. Blood samples were collected before and after a single HFR or HDF treatment to test uremic toxin levels and to calculate clearance rate. The primary efficacy endpoint was to compare uremic toxin levels of indoxyl sulfate (IS), λ-free light chains (λFLC), and ß2-microglobulin (ß2-MG) before and after HFR treatment. Secondary efficacy endpoints was to compare the levels of urea, interleukin-6 (IL-6), P-cresol, chitinase-3-like protein 1 (YKL-40), leptin (LEP), hippuric acid (HPA), trimethylamine N-oxide (TMAO), asymmetric dimethylarginine (ADMA), tumor necrosis factor-α (TNF-α), fibroblast growth factor 23 (FGF23) before and after HFR treatment. The study also undertook a comparative analysis of uremic toxin clearance between a single HFR and HDF treatment. Meanwhile, the lever of serum albumin and branched-chain amino acids before and after a single HFR or HDF treatment were compared. In terms of safety, the study was meticulous in recording vital signs and the incidence of adverse events throughout its duration. RESULTS: The study enrolled 20 patients. After a single HFR treatment, levels of IS, λFLC, ß2-MG, IL-6, P-cresol, YKL-40, LEP, HPA, TMAO, ADMA, TNF-α, and FGF23 significantly decreased (p < 0.001 for all). The clearance rates of λFLC, ß2-MG, IL-6, LEP, and TNF-α were significantly higher in HFR compared to HDF (p values: 0.036, 0.042, 0.041, 0.019, and 0.036, respectively). Compared with pre-HFR and post-HFR treatment, levels of serum albumin, valine, and isoleucine showed no significant difference (p > 0.05), while post-HDF, levels of serum albumin significantly decreased (p = 0.000). CONCLUSION: HFR treatment effectively eliminates uremic toxins from the bloodstream of patients undergoing MHD, especially protein-bound toxins and large middle-molecule toxins. Additionally, it retains essential physiological compounds like albumin and branched-chain amino acids, underscoring its commendable safety profile.

3-Methyl-4-nitrophenol Exposure Deteriorates Oocyte Maturation by Inducing Spindle Instability and Mitochondrial Dysfunction.

3-methyl-4-nitrophenol (PNMC), a well-known constituent of diesel exhaust particles and degradation products of insecticide fenitrothion, is a widely distributed environmental contaminant. PNMC is toxic to the female reproductive system; however, how it affects meiosis progression in oocytes is unknown. In this study, in vitro maturation of mouse oocytes was applied to investigate the deleterious effects of PNMC. We found that exposure to PNMC significantly compromised oocyte maturation. PNMC disturbed the spindle stability; specifically, it decreased the spindle density and increased the spindle length. The weakened spindle pole location of microtubule-severing enzyme Fignl1 may result in a defective spindle apparatus in PNMC-exposed oocytes. PNMC exposure induced significant mitochondrial dysfunction, including mitochondria distribution, ATP production, mitochondrial membrane potential, and ROS accumulation. The mRNA levels of the mitochondria-related genes were also significantly impaired. Finally, the above-mentioned alterations triggered early apoptosis in the oocytes. In conclusion, PNMC exposure affected oocyte maturation and quality through the regulation of spindle stability and mitochondrial function.

Rapid and sustainable HPLC method for the determination of uremic toxins in human plasma samples.

Protein-bound uremic toxins, mainly indoxyl sulfate (3-INDS), p-cresol sulfate (pCS), and indole-3-acetic acid (3-IAA) but also phenol (Pol) and p-cresol (pC), are progressively accumulated during chronic kidney disease (CKD). Their accurate measurement in biomatrices is demanded for timely diagnosis and adoption of appropriate therapeutic measures. Multianalyte methods allowing the establishment of a uremic metabolite profile are still missing. Hence, the aim of this work was to develop a rapid and sensitive method based on high-performance liquid chromatography with fluorescence detection for the simultaneous quantification of Pol, 3-IAA, pC, 3-INDS, and pCS in human plasma. Separation was attained in 12 min, using a monolithic C18 column and isocratic elution with acetonitrile and phosphate buffer containing an ion-pairing reagent, at a flow rate of 2 mL min-1. Standards were prepared in plasma and quantification was performed using the background subtraction approach. LOQ values were ≤ 0.2 µg mL-1 for all analytes except for pCS (LOQ of 2 µg mL-1). The method proved to be accurate (93.5-112%) and precise (CV ≤ 14.3%). The multianalyte application of the method, associated to a reduced sample volume (50 µL), a less toxic internal standard (eugenol) in comparison to the previously applied 2,6-dimethylphenol and 4-ethylphenol, and a green extraction solvent (ethanol), resulted in the AGREE score of 0.62 which is in line with the recent trend of green and sustainable analytical chemistry. The validated method was successfully applied to the analysis of plasma samples from control subjects exhibiting normal levels of uremic toxins and CKD patients presenting significantly higher levels of 3-IAA, pC, 3-INDS, and pCS that can be further investigated as biomarkers of disease progression.

4,4'-Thiobis(2-tert-butyl-5-methylphenol), an antioxidant in medical devices that may cause allergic contact dermatitis.

BACKGROUND: Antioxidants in medical devices, added to protect polymers or adhesives, may also cause contact dermatitis in some individuals. OBJECTIVES: To present data on sensitization to 4,4'-thiobis(2-tert-butyl-5-methylphenol), an antioxidant detected in some types of medical devices, for six patients that experienced eczematous reactions to different medical devices. METHODS: Patch testing with 4,4'-thiobis(2-tert-butyl-5-methylphenol), 1% pet was performed. Gas chromatography-mass spectrometry (GC-MS) was used for identification of 4,4'-thiobis(2-tert-butyl-5-methylphenol) in different medical device products. RESULTS: Six patients with contact allergy to 4,4'-thiobis(2-tert-butyl-5-methylphenol) also had relevant contact allergic reactions to medical devices containing the antioxidant. The presence of the antioxidant in products was detected using GC-MS analysis. CONCLUSIONS: The antioxidant 4,4'-thiobis(2-tert-butyl-5-methylphenol) may cause allergic contact dermatitis after exposure to different medical devices.

SLC22A11 Inserts the Uremic Toxins Indoxyl Sulfate and P-Cresol Sulfate into the Plasma Membrane.

Chronic kidney disease (CKD) is a global health concern affecting millions worldwide. One of the critical challenges in CKD is the accumulation of uremic toxins such as p-cresol sulfate (pCS) and indoxyl sulfate (IS), which contribute to systemic damage and CKD progression. Understanding the transport mechanisms of these prominent toxins is essential for developing effective treatments. Here, we investigated whether pCS and IS are routed to the plasma membrane or to the cytosol by two key transporters, SLC22A11 and OAT1. To distinguish between cytosolic transport and plasma membrane insertion, we used a hyperosmolarity assay in which the accumulation of substrates into HEK-293 cells in isotonic and hypertonic buffers was measured in parallel using LC-MS/MS. Judging from the efficiency of transport (TE), pCS is a relevant substrate of SLC22A11 at 7.8 ± 1.4 µL min-1 mg protein-1 but not as good as estrone-3-sulfate; OAT1 translocates pCS less efficiently. The TE of SLC22A11 for IS was similar to pCS. For OAT1, however, IS is an excellent substrate. With OAT1 and p-aminohippuric acid, our study revealed an influence of transporter abundance on the outcomes of the hyperosmolarity assay; very high transport activity confounded results. SLC22A11 was found to insert both pCS and IS into the plasma membrane, whereas OAT1 conveys these toxins to the cytosol. These disparate transport mechanisms bear profound ramifications for toxicity. Membrane insertion might promote membrane damage and microvesicle release. Our results underscore the imperative for detailed structural inquiries into the translocation of small molecules.

Isolation and characterization of Indigenous Bacilli strains from an oil refinery wastewater with potential applications for phenol/cresol bioremediation.

Phenolic compounds are frequently occurring in wastewaters from various industrial processes at high concentrations, imposing prominent risk to aquatic biosphere and human health. Bioremediation has been proven to be an effective approach to remove these compounds, and hunting for functional organisms is still of primary importance to develop efficient processes. In this study, we report several newly isolated bacillus strains with superior performances in metabolizing phenols, one of which showed paramount efficiencies to metabolize phenol at concentrations up to 1200 mg L-1 and could simultaneously degrade a wide range of other phenolic compounds. The genes encoding for phenol hydroxylase (PH) and catechol-2,3-dioxygenase (C23O) have been detected and characterized, evidencing that phenol degradation occurs via the meta pathway. The GC level of the PH gene was found to be much higher than that of genes from other Bacilli but was quite close to that of the genes from Rhodococcus, and the induction of both enzymes by phenols was confirmed by RT-PCR experiments. We intend to believe this novel strain might be promising to serve as preferred organisms for developing more robust and efficient bioremediation processes of degrading phenolic compounds due to its validated performance.

Development of methods based on low-temperature partitioning (LTP) for monitoring cresols and chlorophenols in sewage sludge, soil, and water in column leaching.

Cresols and chlorophenols are chemical contaminants that are potentially toxic to humans and can be found in sewage sludge. These chemical contaminants can migrate into the sludge-soil-water system when sludge is used as a conditioner for agricultural soils. Thus, the objective of this study was to develop methodologies based on extraction with low-temperature partitioning (LTP) to determine cresols and chlorophenols in sewage sludge, soil, and water. The analysis was performed by gas chromatography coupled with mass spectrometry (GC-MS). The validated methods were applied to monitor cresols and chlorophenols in a column-leaching study of a sludge-soil-water system. Satisfactory results were achieved for selectivity, limit of quantification (LOQ), linearity, accuracy, and precision. In the column leaching study, only 2,4,6-trichlorophenol was quantified in sludge samples after 20 days of the experiment. None of the studied compounds were quantified in soil and leached water samples, due to the degradation promoted by the microorganisms present in the sewage sludge. Finally, validated methods were suitable for monitoring cresols and chlorophenols in the sludge-soil-water system.

The metabolite p-cresol impairs dendritic development, synaptogenesis, and synapse function in hippocampal neurons: Implications for autism spectrum disorder.

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopment disorder resulting from different etiological factors, both genetic and/or environmental. These factors can lead to abnormal neuronal development on dendrite and synaptic function at the central nervous system. Recent studies have shown that a subset of ASD patients display increased circulation levels of the tyrosine metabolite, p-cresol, related to chronic intestinal disorders because of dysbiosis of the intestinal microbiota. In particular, abnormal presence of intestinal Clostridium sp. has been linked to high levels of p-cresol in ASD children younger than 8 years. However, the role of p-cresol during development of the central nervous system is unknown. Here, we evaluated in vitro the effect of p-cresol on neurite outgrowth in N2a and PC12 cell lines and dendritic morphology, synaptic density, neuronal activity, and calcium responses in primary rat hippocampal neurons. p-cresol inhibits neural differentiation and neurites outgrowth in N2a and PC12 neuronal cell lines. In hippocampal neuronal cultures, Sholl's analysis shows a decrease in the dendritic arborization of neurons treated with p-cresol. Synaptic density analyzed with the synaptic markers Piccolo and Shank2 is diminished in hippocampal neurons treated with p-cresol. Electrically evoked intracellular calcium rise was drastically, but reversely, blocked by p-cresol, whereas that spontaneous neuronal activity was severely affected by early addition of the metabolite. These findings show that p-cresol alters dendrite development, synaptogenesis, and synapse function of neurons in culture, therefore, neuronal alterations occurring in ASD children may be related to this metabolite and dysbiosis of the intestinal microbiota.

DNA Damage and Oxidative Stress of Tobacco Smoke Condensate in Human Bladder Epithelial Cells.

Smoking is a major risk factor for bladder cancer (BC), with up to 50% of BC cases being attributed to smoking. There are 70 known carcinogens in tobacco smoke; however, the principal chemicals responsible for BC remain uncertain. The aromatic amines 4-aminobiphenyl (4-ABP) and 2-naphthylamine (2-NA) are implicated in BC pathogenesis of smokers on the basis of the elevated BC risk in factory workers exposed to these chemicals. However, 4-ABP and 2-NA only occur at several nanograms per cigarette and may be insufficient to induce BC. In contrast, other genotoxicants, including acrolein, occur at 1000-fold or higher levels in tobacco smoke. There is limited data on the toxicological effects of tobacco smoke in human bladder cells. We have assessed the cytotoxicity, oxidative stress, and DNA damage of tobacco smoke condensate (TSC) in human RT4 bladder cells. TSC was fractionated by liquid-liquid extraction into an acid-neutral fraction (NF), containing polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, phenols, and aldehydes, and a basic fraction (BF) containing aromatic amines, heterocyclic aromatic amines, and N-nitroso compounds. The TSC and NF induced a time- and concentration-dependent cytotoxicity associated with oxidative stress, lipid peroxide formation, glutathione (GSH) depletion, and apurinic/apyrimidinic (AP) site formation, while the BF showed weak effects. LC/MS-based metabolomic approaches showed that TSC and NF altered GSH biosynthesis pathways and induced more than 40 GSH conjugates. GSH conjugates of several hydroquinones were among the most abundant conjugates. RT4 cell treatment with synthetic hydroquinones and cresol mixtures at levels present in tobacco smoke accounted for most of the TSC-induced cytotoxicity and the AP sites formed. GSH conjugates of acrolein, methyl vinyl ketone, and crotonaldehyde levels also increased owing to TSC-induced oxidative stress. Thus, TSC is a potent toxicant and DNA-damaging agent, inducing deleterious effects in human bladder cells at concentrations of <1% of a cigarette in cell culture media.

Effects of the L-tyrosine-derived bacterial metabolite p-cresol on colonic and peripheral cells.

Specific families of bacteria present within the intestinal luminal content produce p-cresol from L-tyrosine. Although the hosts do not synthesize p-cresol, they can metabolize this compound within their colonic mucosa and liver leading to the production of co-metabolites including p-cresyl sulfate (p-CS) and p-cresyl glucuronide (p-CG). p-Cresol and its co-metabolites are recovered in the circulation mainly conjugated to albumin, but also in their free forms that are excreted in the urine. An increased dietary protein intake raises the amount of p-cresol recovered in the feces and urine, while fecal excretion of p-cresol is diminished by a diet containing undigestible polysaccharides. p-Cresol in excess is genotoxic for colonocytes. In addition, in these cells, this bacterial metabolite decreases mitochondrial oxygen consumption, while increasing the anion superoxide production. In chronic kidney disease (CKD), marked accumulation of p-cresol and p-CS in plasma is measured, and in renal tubular cells, p-cresol and p-CS increase oxidative stress, affect mitochondrial function, and lead to cell death, strongly suggesting that these 2 compounds act as uremic toxins that aggravate CKD progression. p-Cresol and p-CS are also suspected to play a role in the CKD-associated adverse cardiovascular events, since they affect endothelial cell proliferation and migration, decrease the capacity of endothelial wound repair, and increase the senescence of endothelial cells. Finally, the fact that concentration of p-cresol is transiently increased in young autistic children biological fluids, and that intraperitoneal injection of p-cresol in animal models induces some behavioral characteristics observed in the autism spectrum disorders (ASD), raise the view that p-cresol may possibly represent one of the components involved in ASD etiology. Further pre-clinical and clinical studies are obviously needed to determine if the lowering of p-cresol and/or p-CS circulating concentrations, by dietary and/or pharmacological means, would allow, by itself or in combination with other interventions, to improve CKD progression and associated cardiovascular outcomes, as well as some neurological outcomes in children with an early diagnosis of autism.

Aggregation Kinetics of Polysorbate 80/m-Cresol Solutions: A Small-Angle Neutron Scattering Study.

Polysorbate 80 (PS80), a nonionic surfactant used in pharmaceutical formulation, is known to be incompatible with m-cresol, an antimicrobial agent for multi-dose injectable formulations. This incompatibility results in increased turbidity caused by micelle aggregation progressing over weeks or longer, where storage temperature, ionic strength, and component concentration influence the aggregation kinetics. Small-angle neutron scattering (SANS) analysis of PS80/m-cresol solutions over a pharmaceutically relevant concentration range of each component reveals the cause of aggregation, the coalescence mechanism, and aggregate structure. PS80 solutions containing m-cresol concentrations below ≈2.0 mg/mL and above ≈4.5 mg/mL are kinetically stable and do not aggregate over a 50 h period. At 5 mg/mL of m-cresol, the mixture forms a kinetically stable microemulsion phase, despite being well below the aqueous solubility limit of m-cresol. Solutions containing intermediate m-cresol concentrations (2.0-4.5 mg/mL) are unstable, resulting in aggregation, coalescence, and eventual phase separation. In unstable solutions, two stages of aggregate growth (nucleation and power-law growth) are observed at m-cresol concentrations at or below ≈3.6 mg/mL. At higher m-cresol concentrations, aggregates experience a third stage of exponential growth. A single kinetic model is developed to explain the stages of aggregate growth observed in both kinetic mechanisms. This work establishes the phase diagram of PS80/m-cresol solution stability and identifies component concentrations necessary for producing stable formulations.