Sulfoxaflor insecticide exhibits cytotoxic or genotoxic and apoptotic potential via oxidative stress-associated DNA damage in human blood lymphocytes cell cultures

The need for foodstuff that emerged with the rapidly increasing world population made fertilizers and pesticides inevitable to obtain maximum efficiency from existing agricultural areas. Sulfoxaflor is currently the only member of the new sulfoximine insecticide subclass of nicotinic acetylcholine receptor agonists. In the study, it was aimed to determine the in vitro genetic, oxidative damage potential, genotoxic and apoptotic effects of three different concentrations (10 µg/mL, 20 µg/mL and 40 µg/mL) of sulfoxaflor insecticide in the cultures of blood lymphocytes. In this study, the single-cell gel electrophoresis (comet), Cytokinesis Block Micronuclues Test (MN test), flow cytometry and measurement of Catalase (CAT) enzyme activity were used to determine genotoxic, apoptotic effects and oxidative damage potential, respectively. It found that there is a decrease in CPBI values and Live cell numbers. It was observed an increase in late apoptotic and necrotic cell numbers, Micronucleus frequency, and Comet analysis parameters (GDI and DCP). There is a significant difference between negative control and all concentration of insecticide for Cytokinesis Block Proliferation Index (CBPI) values and late apoptotic, necrotic and viable cell counts. An increase in CAT enzyme levels was observed at 10 and 20 µg/mL concentrations compared to control., It is found that CAT enzyme activity was inhibited at concentrations of 40 µg/mL. This study is crucial as it is the first study to investigate the impact of Sulfoxaflor insecticide on peripheral blood lymphocyte cells. The genotoxic, oxidative damage, and apoptotic effects of Sulfoxafluor insecticide on the results obtained and its adverse effects on other organisms raise concerns about health and safety.

Spectral shift supported epichlorohydrin toxicity and the protective role of sage

In this study, the toxicity of epichlorohydrin, a chemical intermediate, was investigated by using Allium cepa L. test material as a bio-indicator. In addition, the protective role of sage leaf extract (Slex) against this toxicity was investigated. Toxicity was handled with the help of physiological (germination percentage, root elongation, and weight gain), cytogenetic (mitotic index = MI, micronucleus = MN, and chromosomal abnormalities = CAs), biochemical (malondialdehyde = MDA, superoxide dismutase = SOD, and catalase = CAT), and anatomical (root meristem cell damages) parameters. A. cepa bulbs were divided into 6 groups (1 control, 5 applications). The bulbs in the control group were treated with tap water, and the bulbs in the application group were treated with epichlorohydrin at a dose of 100 mg/L and Slex at two different doses (190 mg/L and 380 mg/L) and germinated. Germination process was continued uninterruptedly for 72 h in all groups. At the end of the period, physiological parameter measurements were carried out in the bulbs. In addition, root tips were collected and made ready for cytogenetic, biochemical, and anatomical measurements and microscopic observations. As a result, exposure to epichlorohydrin caused statistically significant (p < 0.05) decreases in germination percentage, root length, weight gain, and MI, and statistically significant (p<0.05) increases in MN frequency, CA numbers, MDA level, SOD, and CAT enzyme activities. Epichlorohydrin exposure induced CAs such as fragment, sticky chromosome, unequal distribution of chromatin, reverse polarization, and disordered mitosis in root meristem cells. The toxicity of epichlorohydrin was due to its interaction with DNA, and this interaction was confirmed by the spectral shift in the DNA spectrum. In addition, epichlorohydrin caused anatomical damages such as epidermis cell damage, cortex cell damage, thickening of the cortex cell wall, and flattened cell nuclei in root meristem cells. The application of Slex together with epichlorohydrin decreased the toxicity of epichlorohydrin and again caused statistically significant (p < 0.05) improvements in the values of all the parameters examined. In other words, germination percentage, root length, weight gain, and MI increased again and MN frequency, CAs numbers, MDA level, SOD, and CAT enzyme activities decreased. It was determined that this improvement was even more pronounced at 380 mg/L dose of Slex. As a result, it was determined that epichlorohydrin caused multiple-toxicity for the investigated indicator organism, and Slex had a reducing role in this toxicity. For this reason, Slex should be included in the daily diet as an antioxidant beverage in order to protect from the toxicity of chemical agents exposed in daily life or to reduce their effects.

Inhibitory effect of TCCE on CCl4-induced overexpression of IL-6 in acute liver injury

Terminalia catappa L. leaves have been shown to protect against acute liver injury produced by some hepatotoxicants, but the active components and mechanisms are not clear. This study was designed to characterize the protective effects of the chloroform fraction of the ethanol extract of T. catappa leaves (TCCE) against carbon tetrachloride (CCl4)-induced hepatotoxicity in mice, and analyze the changes in expression level of interleukin-6 (IL-6) in the process. It was found that TCCE pretreatment (10 or 30 mg/kg, ig) protected mice from CCl4 toxicity, as evidenced by the reversed alterations in serum alanine aminotransferase (sALT) and serum aspartate aminotransferase (sAST) activities. Additionally liver tissues were subjected to RT-PCR, Western blot and immunohistochemistry to analyze changes in IL-6 expression. It was found that TCCE markedly suppressed the CCl4-induced over-transcription of IL-6 gene. Consistent with the result, the expression of IL-6 protein was also blocked by TCCE in CCl4-stimulated mice, especially in the area around central vein on liver tissue section. In conclusion, TCCE is effective in protecting mice from the hepatotoxicity produced by CCl4, and the mechanisms underlying its protective effects may be related to the inhibition on the overexpression of IL-6 mainly around terminal hepatic vein.

Disruption of androgen regulation in the prostate by the environmental contaminant hexachlorobenzene

Hexachlorobenzene (HCB) is a persistent environmental contaminant that has the potential to interfere with steroid hormone regulation. The prostate requires precise control by androgens to regulate its growth and function. To determine if HCB impacts androgen action in the prostate, we used a number of methods. Our in vitro cell-culture-based assay used a firefly luciferase reporter gene driven by an androgen-responsive promoter. In the presence of dihydrotestosterone, low concentrations (0.5-5 nM) of HCB increased the androgen-responsive production of firefly luciferase and high concentrations of HCB (> 10 microM) suppressed this transcriptional activity. Results from a binding assay showed no evidence of affinity between HCB and the androgen receptor. We also tested HCB for in vivo effects using transgenic mice in which the transgene was a prostate-specific, androgen-responsive promoter upstream of a chloramphenicol acetyl transferase (CAT) reporter gene. In 4-week-old mice, the proportion of dilated prostate acini, a marker of sexual maturity, increased in the low HCB dose group and decreased in the high HCB dose mice. In the 8-week-old mice, there was a significant decrease in both CAT activity and prostate weight upon exposure to 20 mg/kg/day HCB. Therefore, in vitro and in vivo data suggest that HCB weakly agonizes androgen action, and consequently, low levels of HCB enhanced androgen action but high levels of HCB interfered. Environmental contaminants have been implicated in the rising incidence of prostate cancer, and insight into the mechanisms of endocrine disruption will help to clarify their role.

Gene induction studies and toxicity of chemical mixtures

As part of its mixtures program, the Agency for Toxic Substances and Disease Registry (ATSDR) supports in vitro and limited in vivo toxicity testing to further our understanding of the toxicity and health effects of chemical mixtures. There are increasing concerns that environmental chemicals adversely affect the health of humans and wildlife. These concerns have been augmented by the realization that exposure to chemicals often occurs to mixtures of these chemicals that may exhibit complex synergistic or antagonistic interactions. To address such concerns, we have conducted two studies with techniques that are being used increasingly in experimental toxicology. In the first study, six organochlorine pesticides (4,4 -DDT, 4,4 -DDD, 4,4 -DDE, aldrin, dieldrin, or endrin) were selected from the ATSDR Comprehensive Environmental Response, Compensation and Liability Act of 1980 (or Superfund) priority list and tested for their ability to modulate transcriptional activation of an estrogen-responsive reporter gene in transfected HeLa cells. In these assays, HeLa cells cotransfected with an expression vector encoding estrogen receptor and an estrogen-responsive chloramphenicol acetyltransferase (CAT) reporter plasmid were dosed with and without selected environmental chemicals either individually or in defined combinations. Estradiol consistently elicited 10- to 23-fold dose-dependent inductions in this assay. By contrast, all six of the organochlorine pesticides showed no detectable dose-related response when tested either individually or in binary combinations. Thus, these chemicals as binary mixtures do not exhibit any additional estrogenicity at the levels tested in these assays. In the second study, arsenic [As(V)], cadmium [Cd(II)], chromium [Cr(III, VI)], and lead [Pb(II)] were tested in a commercially developed assay system, CAT-Tox (L), to identify metal-responsive promoters and to determine whether the pattern of gene expression changed with a mixture of these metals. This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal-transduction pathways. Singly, As(V), Cd(II), Cr(III, VI), and Pb(II) produced complex induction profiles in these assays. However, no evidence of synergistic activity was detected with a mixture of Cd(II), Cr(III), and Pb(II). These results have shown metal activation of gene expression through several previously unreported signal-transduction pathways and thus suggest new directions for future studies into their biochemical mechanisms of toxicity. In conclusion, the (italic)in vitro(/italic) methods used in these studies provide insights into complex interactions that occur in cellular systems and could be used to identify biomarkers of exposure to other environmental chemical mixtures.

PreproEndothelin-1 Expression in Human Mesangial Cells: Evidence for a p38 Mitogen-Activated Protein Kinase/Protein Kinases-C—Dependent Mechanism

Abstract. Endothelin-1 (ET-1) has been implicated in the pathogenesis of renal inflammation. This study investigated the mechanisms underlying the synergistic upregulation of preproET-1 gene expression in human mesangial cells after co-stimulation with thrombin and tumor necrosis factor α (TNFα). Whereas thrombin induced a moderate upregulation of preproET-1 mRNA, co-stimulation with TNFα resulted in a strong and protracted upregulation of this mRNA species. Thrombin+TNFα-induced upregulation of preproET-1 expression was found to require p38 mitogen-activated protein kinase and protein kinases C, whereas activation of extracellular signal-regulated kinase, c-Jun-N-terminal kinase, or intracellular Ca2+ release were not required. Actinomycin D chase experiments suggested that enhanced stability of preproET-1 mRNA did not account for the increase in transcript levels. PreproET-1 promoter analysis demonstrated that the 5′-flanking region of preproET-1 encompassed positive regulatory elements engaged by thrombin. Negative modulation of thrombin-induced activation exerted by the distal 5′ portion of preproET-1 promoter (-4.4 kbp to 204 bp) was overcome by co-stimulation with TNFα, providing a possible mechanism underlying the synergistic upregulation of preproET-1 expression by these two agonists. In conclusion, human mesangial cell expression of preproET-1 may be increased potently in the presence of two common proinflammatory mediators, thereby providing a potential mechanism for ET-1 production in inflammatory renal disease.

Inhibition of HIV-1 replication and infectivity by expression of a fusion protein, VPR-anti-integrase single-chain variable fragment (SFv): intravirion molecular therapies

OBJECTIVES

To deliver antiretroviral agents or other foreign proteins into progeny virions and evaluate their inhibitory effect on human immunodeficiency virus type 1 (HIV-1) replication.

STUDY DESIGN/METHODS

HIV-1 encodes proteins in addition to gag, pol, and env, some of which are packaged into virus particles. One essential retroviral enzyme is integrase (IN), which has been used as a target for developing agents that inhibit virus replication. In previous studies, we demonstrated that intracellular expression of single-chain variable antibody fragments (SFvs), which bind to IN, results in resistance to productive HIV-1 infection in T-lymphocytic cells. Because the highly conserved accessory HIV-1 Vpr protein can be packaged within virions in quantities similar to those of the major structural proteins, this primate lentiviral protein may be used as a fusion partner to deliver antiviral agents or other foreign proteins into progeny virions. In these studies, the fusion proteins Vpr-chloramphenicol acetyl transferase (CAT) and Vpr-SFv-IN have been developed. Stable transfectants expressing these fusion proteins were generated from PA317 cells and SupT1 T-lymphocytic cells and analyzed using immunofluorescence microscopy. After challenge of SupT1 cells with HIV-1, p24 antigen expression was evaluated. The incorporation of these fusion proteins were evaluated by immunoprecipitation of virions using a Vpr antibody.

RESULTS

Expression of the fusion proteins was confirmed by immunofluorescent staining in PA317 cells transfected with the plasmids expressing Vpr-CAT and Vpr-SFv-IN proteins. Stable transfectants expressing these fusion proteins were generated from SupT1 T-lymphocytic cells. When challenged, HIV-1 replication, as measured by HIV-1 p24 antigen expression, was inhibited in cells expressing Vpr-SFv-IN. It was demonstrated that Vpr-chloramphenicol acetyl transferase (Vpr-CAT and Vpr-SFv-IN proteins can be efficiently packaged into the virions and that Vpr-SFv-IN also decreases the infectivity of virions into which it is encapsidated.

CONCLUSIONS

An anti-integrase single-chain variable fragment moiety can be delivered into HIV-1 virions by fusing it to Vpr. Vpr-SFv-IN decreases HIV-1 production in human T-lymphocytic cells. The benefits of "intravirion" gene therapy include immunization of target cells as well as decreasing infectivity of HIV-1 virions harboring the fusion construct. Thus, this approach to anti-HIV-1 molecular therapies has the potential to increase inhibitory effects against HIV-1 replication and virion spread.

Cytotoxic T lymphocyte responses to proteins encoded by heterologous transgenes transferred in vivo by adenoviral vectors

Although replication-deficient adenovirus (Ad) vectors are efficient vehicles for in vivo gene transfer, persistence of expression of the Ad genome is limited in immunocompetent hosts by cellular immunity directed against the gene product of the vector. While most attention has been focused on cytotoxic T lymphocytes (CTL) directed against the low-level early and late Ad gene expression in the Ad vector-infected target cells, significant cellular immunity is likely also directed against the product of heterologous transgenes. To evaluate this concept, in vivo generation of CTL was evaluated in C57B1/6 and BALB/c mice with Ad vectors expressing a variety of heterologous transgenes, including Escherichia coli chloramphenicol acetyl transferase (CAT), beta-galactosidase (beta-Gal), cytosine deaminase, and human thrombopoietin (hTPO), with an Ad vector expressing no transgene ("null") as a control. Following intravenous administration of Ad vectors, spleen cells were harvested 2 weeks later, stimulated for 5 days with syngeneic cells infected with various Ad vectors, and then evaluated for CTL activity using 51Cr-release from syngeneic Ad vector-infected targets. In all cases, CTL directed against the heterologous transgene products was observed, although there were differences in the amounts of transgene-specific CTL. CTL directed against the transgene were also observed with other routes of administration, including intratracheal, subcutaneous, and intraperitoneal administration. These observations suggest that inclusion of a heterologous transgene in Ad vectors enhances the elimination of vector-infected cells, a circumstance that will be partially circumvented using autologous genes. For some applications, specific immune responses to products of transgenes delivered by Ad vectors might be exploited for therapeutic purposes.

Translational regulation of angiotensin II type 1A receptor. Role of upstream AUG triplets

The cDNA sequence of rat angiotensin II type 1A receptor (AT1AR) shows that AT1AR transcripts have AUG triplets in the 5'-leader region that may begin a short open reading frame encoding an 11-amino acid peptide. In this study, the mutational inactivation of the start codon of the short open reading frame in AT1AR-chloramphenicol acetyltransferase (CAT) reporter gene constructs resulted in a 2.6-fold increase in CAT activity, whereas CAT transcript levels were not affected. Furthermore, experiments with rat AT1AR cDNA-transfected Cos-7 cells revealed that mutagenesis of the upstream AUG increased the AT1AR protein up to 2.5-fold, although AT1AR transcript levels showed no changes. The synthetic peptide corresponding to the sequence of the short open reading frame significantly suppressed the amount of AT1AR product in the in vitro translation system. The inhibiting effect of the short open reading frame appears to operate at least in part at the level of translation initiation, because polysome analysis with transfected Cos-7 cells showed that mutagenesis of the upstream AUG resulted in a shift of AT1AR mRNA distribution from a smaller to larger fraction of polysomes. Taken together, these results show that the upstream AUG inhibits translational regulation, suggesting that the short open reading frame in the 5'-leader region of AT1AR transcripts has a certain role in the translation of AT1AR protein.

Intratracheal gene delivery to the mouse airway: characterization of plasmid DNA expression and pharmacokinetics

Intratracheal administration of plasmid DNA resulted in gene expression in mouse airways in the absence of any enhancing agent. Administration of plasmid DNA encoding the chloramphenicol acetyltransferase gene (CAT) in sterile water lead to CAT transgene expression that peaked between 1 and 3 days and was detected up to 28 days after DNA administration. Transgene expression was independent of mouse gender, age and strain. Levels of expression from DNA in various isotonic solutions did not differ from levels obtained with DNA administered in water, suggesting that transfection is not dependent on damage to airway cells caused by a hypo-osmotic delivery vehicle. Pharmacokinetic studies using radiolabeled plasmid DNA showed that DNA was rapidly degraded, while higher levels of radioactivity were retained for longer duration following administration of cationic liposome-DNA complexes in the airway. Southern blot and PCR analysis confirmed that DNA complexed with DOTMA-DOPE was retained in the airways for a longer period. However, cationic liposomes DOTMA-DOPE (1:1) or DOTAP complexed with DNA, did not enhance expression over DNA alone. These results suggest that 'naked' plasmid DNA should be included as a control in all studies on intratracheal gene delivery using nonviral systems.