In vitro effects of monophthalates on cytokine expression in the monocytic cell line THP-1 and in peripheral blood mononuclear cells from allergic and non-allergic donors

It has recently been shown that plasticizers are present in indoor air dust, which may lead to human exposure via the inhalation route. Moreover, studies have indicated that plasticizers may possess adjuvant effects increasing the health damaging potential of allergens. The aim of this study was to investigate the in vitro effect of metabolites of phthalate plastisizers, such as whether an adjuvant effect is paralleled by changes of the cytokine expression in the monocytic cell line THP-1 and in peripheral blood mononuclear cells (PBMCs) from allergics and non-allergics. The toxicity monitored by cell viability was determined by incubating THP-1 cells with a 10-fold dilution series of monophthalates for 24 h. At different points in time cytokine expression (IL-1β, IL-6, IL-12 (p35)) in THP-1 cells incubated with non-toxic concentrations of monophthalate (2–20 μg/ml)±LPS (1 μg/ml) were determined using Quantitative Competitive RT-PCR. PBMCs from allergics and non-allergics were incubated with monophthalate 220 μg/ml) for up to 48 h and cytokine expression (IL-4, IL-5, IFN-γ) was measured using real-time PCR. The cytotoxic level of monophthalates is 20–200 μg/ml, depending on the individual monophthalate. There seems to be a correlation between increasing side-chain length and toxicity. Monophthalates did not induce changes in cytokine expression in THP-1 cells, though there is an increase when co-incubating with LPS. Cytokine expression in PBMC seems virtually unchanged when co-incubated with monophthalate, though mono-n-butyl phthalate (MBUP) tends to increase the level of IL-4 in PBMCs from allergic individuals. The two cellular models demonstrated the dynamics of regulated cytokine mRNA and are applicable for in vitro immunotoxicological investigations. The results regarding monophthalates suggest these to have a limited effect on cytokine expression in the monocytic cell line THP-1 and weak effect on cytokine expression in PBMCs from allergic and non-allergic individuals.     

Prediction of the contact sensitizing potential of chemicals using analysis of gene expression changes in human THP-1 monocytes

The aim of this study was to find differentially regulated genes in THP-1 monocytic cells exposed to sensitizers and nonsensitizers and to investigate if such genes could be reliable markers for an in vitro predictive method for the identification of skin sensitizing chemicals. Changes in expression of 35 genes in the THP-1 cell line following treatment with chemicals of different sensitizing potential (from nonsensitizers to extreme sensitizers) were assessed using real-time PCR. Verification of 13 candidate genes by testing a large number of chemicals (an additional 22 sensitizers and 8 nonsensitizers) revealed that prediction of contact sensitization potential was possible based on evaluation of changes in three genes: IL8, HMOX1 and PAIMP1. In total, changes in expression of these genes allowed correct detection of sensitization potential of 21 out of 27 (78%) test sensitizers. The gene expression levels inside potency groups varied and did not allow estimation of sensitization potency of test chemicals. Results of this study indicate that evaluation of changes in expression of proposed biomarkers in THP-1 cells could be a valuable model for preliminary screening of chemicals to discriminate an appreciable majority of sensitizers from nonsensitizers.     

Influence of bovine serum albumin pre-incubation on toxicity and ER stress-apoptosis gene expression in THP-1 macrophages exposed to ZnO nanoparticles

When entering a biological environment, proteins could be adsorbed onto nanoparticles (NPs), which can potentially influence the toxicity of NPs. This study used bovine serum albumin (BSA) as the model for serum protein and investigated its interactions with three different types of ZnO NPs, coded as XFI06 (pristine NPs of 20?nm), NM110 (pristine NPs of 100?nm) and NM111 (hydrophobic NPs of 130?nm). Atomic force microscope indicated the adsorption of BSA to ZnO NPs, leading to the increase of NP diameters. Pre-incubation with BSA did not significantly affect hydrodynamic size but decreased Zeta potential of NM110 and NM111. The fluorescence and synchronous fluorescence of BSA were quenched after pre-incubation with ZnO NPs, and the quenching effects were more obvious for XFI06 and NM110. Exposure to all types of ZnO NPs significantly induced cytotoxicity and lysosomal destabilization, which was slightly alleviated when NPs were pre-incubated with BSA. However, ZnO NPs with or without pre-incubation of BSA resulted in comparable intracellular Zn ions, glutathione and reactive oxygen species in THP-1 macrophages. Exposure to ZnO NPs promoted the expression of endoplasmic reticulum (ER) stress markers (DDIT3 and XBP-1s) and apoptosis genes (CASP9 and CASP12). Pre-incubation with BSA had minimal impact on ER stress gene expression but decreased apoptosis gene expression. Combined, these results suggested that pre-incubation with BSA could modestly alleviate the cytotoxicity and reduce ER stress related apoptosis gene expression in THP-1 macrophages after ZnO NP exposure.     

Organic extract of diesel exhaust particles stimulates expression of Ia and costimulatory molecules associated with antigen presentation in rat peripheral blood monocytes but not in alveolar macrophages

We hypothesized that diesel exhaust particles (DEP) induce the activation of antigen-presenting cells (APC) in lung. The present study was designed to clarify the following about DEP: (1) whether it affects the expression of Ia and B7 molecules in alveolar macrophages (AM) as a mature cell or in peripheral blood monocytes (PBM) as an immature cell, (2) if it affects the antigen-presenting (AP) activity of PBM, (3) what component of DEP is responsible for the effects, and (4) whether the effect of DEP is related to oxidative stress. DEP was extracted with methylene chloride. Cells were exposed to whole DEP, organic extract, or residual particles for 24 h. Cell-surface molecules were measured by flow cytometry. AP activity was assessed by antigen-specific T cell proliferation. Whole DEP or organic extract significantly increased the expression of Ia and B7 molecules on PBM but not on AM. No significant effect of residual particles was observed. A low concentration of organic extract also increased the AP activity of PBM. When the induction of an antioxidative enzyme was assessed, heme oxygenase-1 protein was found to be significantly increased by exposure to whole DEP, and the organic extract was more effective than the residual particles. Furthermore, the organic extract-induced expression of Ia antigen on PBM was reduced by the addition of an antioxidative agent. These results suggest that DEP may act on immature APC and enhance their AP activity and that the action contributing to oxidative stress may be mediated by organic compounds of DEP.     

The effect of body mass index on glucagon-like peptide receptor gene expression in the post mortem brain from individuals with mood and psychotic disorders

There is an increasing interest in the putative role of glucagon-like peptide 1 receptor (GLP-1R) agonists as novel therapeutic agents for mental disorders. Herein, we investigated the expressions of GLP-1R and GLP-2R genes, and its relationship with body mass index (BMI), in the post-mortem brain tissue of patients with mood (MD) and psychotic disorders. Brain samples were localized to the dorsolateral prefrontal cortex (dlPFC) (n?=?459) and hippocampus (n?=?378). After adjustment for age, sex, ethnicity, post-mortem interval (PMI) and BMI, we observed significant differences, between healthy controls and MD subjects, in GLP-1R and GLP-2R gene expression in the dlPFC (β?=?1.504, p?=?0.004; and β?=?1.305, p?=?0.011, respectively); whereas in the hippocampus, only GLP-1R expression was significantly associated with MD (β?=??1.28, p?=?0.029). No significant differences were found in relation to schizophrenia. In addition, we observed a moderating effect of MD diagnosis on the associations between BMI, GLP-1R and GLP-2R expression values in the dlPFC (β?=??0.05, p?=?0.003; and β?=??0.04, p?=?0.004, respectively). There was a similar moderating effect for GLP-1R in the hippocampus (β?=?0.043, 95% CI 0.003; 0.08 p?=?0.03), but in an opposite direction than observed in the dlPFC. This is the first evidence of abnormal gene expression of GLP-1R and GLP-2R in postmortem brain of individuals with MD, providing a rationale for further inquiry and proof of principle interventional studies.