Effect of thiram on chick chondrocytes in culture

Molecular mechanisms of environmental pollutant-induced cartilage damage: from developmental disorders to osteoarthritis

The objective of the present study was to review the molecular mechanisms of the adverse effects of environmental pollutants on chondrocytes and extracellular matrix (ECM). Existing data demonstrate that both heavy metals, including cadmium (Cd), lead (Pb), and arsenic (As), as well as organic pollutants, including polychlorinated dioxins and furans (PCDD/Fs) and polychlorinated biphenyls (PCB), bisphenol A, phthalates, polycyclic aromatic hydrocarbons (PAH), pesticides, and certain other organic pollutants that target cartilage ontogeny and functioning. Overall, environmental pollutants reduce chondrocyte viability through the induction apoptosis, senescence, and inflammatory response, resulting in cell death and impaired ECM production. The effects of organic pollutants on chondrocyte development and viability were shown to be mediated by binding to the aryl hydrocarbon receptor (AhR) signaling and modulation of non-coding RNA expression. Adverse effects of pollutant exposures were observed in articular and growth plate chondrocytes. These mechanisms also damage chondrocyte precursors and subsequently hinder cartilage development. In addition, pollutant exposure was shown to impair chondrogenesis by inhibiting the expression of Sox9 and other regulators. Along with altered Runx2 signaling, these effects also contribute to impaired chondrocyte hypertrophy and chondrocyte-to-osteoblast trans-differentiation, resulting in altered endochondral ossification. Several organic pollutants including PCDD/Fs, PCBs and PAHs, were shown to induce transgenerational adverse effects on cartilage development and the resulting skeletal deformities. Despite of epidemiological evidence linking human environmental pollutant exposure to osteoarthritis or other cartilage pathologies, the data on the molecular mechanisms of adverse effects of environmental pollutant exposure on cartilage tissue were obtained from studies in laboratory rodents, fish, or cell cultures and should be carefully extrapolated to humans, although they clearly demonstrate that cartilage should be considered a putative target for environmental pollutant toxicity.

The analysis base study on mechanical double enzyme technique for isolating and culturing primary chondrocytes

The mechanical-double enzyme method was used in the current study to isolate and culture primary chondrocytes from the chicken growth plates. The feasibility and practicability of the approach were determined by using trypan blue staining, toluidine blue staining, PCR, and flow cytometry. The immunofluorescence assay was also used to effectively identify chondrocytes, demonstrating the expression of chondrocyte-specific secreted products (Col-II and Aggrecan). The exterior morphology of chondrocytes was studied at several stages, revealing significant changes in cell shape with each generation. Notably, compared to earlier approaches, the mechanical-double enzyme strategy revealed enhanced cell adhesion and much reduced apoptosis rates. The findings indicate that this novel method has great potential for efficient primary chondrocytes culture, providing important insight into chondrocyte ba research and future applications in cartilage tissue engineering. The following technical points are included in this method:•Isolation and culturing primary chondrocytes by a mechanical-double enzyme approach.•The evaluation of cell adhesion and apoptosis of mechanical double enzyme approach as compared to previous approaches.•The confirmation of chondrocyte-specific secreted products' expression via toluidine blue staining, PCR, and immunofluorescence assays.

Oral administration of thiram inhibits brush border membrane enzymes, oxidizes proteins and thiols, impairs redox system and causes histological changes in rat intestine: A dose dependent study

Pesticides are extensively employed worldwide, especially in agriculture to control weeds, insect infestation and diseases. Besides their targets, pesticides can also affect the health of non-target organisms, including humans The present study was conducted to study the effect of oral exposure of thiram, a dithiocarbamate fungicide, on the intestine of rats. Male rats were administered thiram at doses of 100, 250, 500 and 750 mg/kg body weight for 4 days. This treatment reduced cellular glutathione, total sulfhydryl groups but enhanced protein carbonyl content and hydrogen peroxide levels. In addition, the activities of all major antioxidant enzymes (catalase, thioredoxin reductase, glutathione peroxidase and glutathione-S-transferase) except superoxide dismutase were decreased. The antioxidant power of the intestine was impaired lowering the metal-reducing and free radical quenching ability. Administration of thiram also led to inhibition of intestinal brush border membrane enzymes, alkaline phosphatase, γ-glutamyl transferase, leucine aminopeptidase and sucrase. Activities of enzymes of pentose phosphate pathway, citric acid cycle, glycolysis and gluconeogenesis were also inhibited. Histopathology showed extensive damage in the intestine of thiram-treated rats at higher doses. All the observed effects were in a thiram dose-dependent manner. The results of this study show that thiram causes significant oxidative damage in the rat intestine which is associated with the marked impairment in the antioxidant defense system.

Effect of total flavonoids of Rhizoma Drynariae in thiram induced cytotoxicity of chondrocyte via BMP-2/Runx2 and IHH/PTHrP expressions

Tibial Dyschondroplasia (TD) is a prevailing skeletal disorder that mainly affects rapidly growing avian species. It results in reduced bone strength, lameness and an increase risk of fragility fractures. Total flavonoids of Rhizoma drynariae (TFRD) have been used as an effective treatment of different bone diseases in humans. The current in vitro study was conducted to explore the therapeutic effect of TFRD on thiram-induced cytotoxicity in avian growth plate cells via bone morphogenetic protein-2/runt related transcription factor-2 (BMP-2/Runx2) and Indian hedgehog/Parathyroid hormone-related peptide (IHH/PTHrP) expressions. Chondrocytes were isolated, cultured and refined from chicken's tibial growth plates in a special medium. Then chondrocytes were treated with sublethal thiram having less concentration (2.5 μg/mL) to induce cytotoxicity of chondrocyte, and then treated with providential doses (100 μg/mL) of TFRD. Thiram caused distorted morphology of chondrocytes, nuclei appeared disintegration or lysed along with decreased expressions of BMP-2/Runx2 and IHH/PTHrP. TFRD administration not only enhanced the viability of chondrocytes by itself, but also well restored the damage caused by thiram on growth plate chondrocytes by significantly up-regulating the expressions of BMP-2/Runx2 and IHH/PTHrP. Therefore, this study provides a novel insight into the further treatment of TD and other skeletal ailments and lays the foundation for prevention and treatment.

The case for thyroid disruption in early life stage exposures to thiram in zebrafish (Danio rerio)

Thiram, a pesticide in the dithiocarbamate chemical family, is widely used to prevent fungal disease in seeds and crops. Its off-site movement to surface waters occurs and may place aquatic organisms at potential harm. Zebrafish embryos were used for investigation of acute (1 h) thiram exposure (0.001-10 µM) at various developmental stages. Survival decreased at 1 µM and 10 µM and hatching was delayed at 0.1 µM and 1 µM. Notochord curvatures were seen at 0.1 and 1 μM thiram when exposure was initiated at 2 and at 10 hpf. Similar notochord curvatures followed exposure to the known TPO inhibitor, methimazole (MMI). Changes were absent in embryos exposed at later stages, i.e., 12 hpf. In embryos exposed to 0.1 or 1 μM at 10 hpf, levels of the thyroid enzyme, Deiodinase 3, increased by 12 hpf. Thyroid peroxide (TPO), important in T4 synthesis, decreased by 48 hpf in embryos exposed to 1 µM at 10 hpf. Thiram toxicity was stage-dependent and early life stage exposure may be responsible for adverse effects seen later. These effects may be due to impacts on the thyroid via regulation of specific thyroid genes including TPO and Deiodinase 3.

Adverse effects of thiram-treated seed ingestion on the reproductive performance and the offspring immune function of the red-legged partridge

Pesticide research traditionally has focused on compounds with high acute toxicity or persistence, but the adverse sublethal effects of pesticides with different properties also may have important consequences on exposed wildlife. The authors studied the effects of thiram, a fungicide used for seed coating with known effects as endocrine disruptor. Red-legged partridges (Alectoris rufa; n = 15 pairs per treatment group) were fed wheat treated with 0%, 20%, or 100% of the thiram application rate used in autumn (25 d) and late winter (10 d) to mimic cereal sowing periods. The authors studied the effects on reproductive performance, carotenoid-based ornamentation and cellular immune responsiveness of adult partridges, and their relationship with changes in oxidative stress biomarkers and plasma biochemistry. The authors also studied the effect of parental exposure on egg antioxidant content and on the survival, growth, and cellular immune response of offspring. Exposure to thiram-coated seeds delayed egg laying, reduced clutch size, and affected egg size and eggshell thickness. Partridges exposed to the 20% thiram dose exhibited reduced egg fertility and brood size (55% and 28% of controls, respectively). Chick survival was unaffected by parental exposure to treated seeds, but adverse effects on their growth rate and cellular immune response were apparent. These effects on reproduction and immune function may have important demographic consequences on farmland bird populations.

Chromosomal aberrations in cultured human lymphocytes treated with the fungicide, Thiram

In vitro effects of different concentrations of Thiram were tested on human lymphocytes to determine, by means of the chromosome aberrations (CAs) assay, whether this fungicide could induce clastogenic damage. Evidences of the effect of Thiram on human lymphocytes were limited to sister chromatid exchange, micronuclei formation, and comet assays. We evaluated 0.01, 0.1, 1.2, and 12.0 μg/mL of Thiram, where 0.01 μg/mL represent the acceptable daily intake dose set by the World Health Organization and the Food and Agriculture Organization for fruit and vegetables, whereas 0.1, 1.2, and 12.0 μg/mL are its multiple values. Results indicated that human lymphocytes treated in vitro with Thiram at concentrations of 1.20 and 12.0 μg/mL significantly increased CAs frequency, compared with the negative control, whereas at lower concentrations (0.01 and 0.1 μg/mL), this effect was not observed. However, Thiram showed a clastogenic effect also at the concentration value of 1.2 μg/mL that represents a lower value with respect to the residue limits found in Italy for grapes, strawberries, potatoes, tobacco, and other fruits and vegetables. Finally, according to some evidence obtained from the study of other fungicides, Thiram produced a significant reduction in the mitotic index with increasing concentration.

Effect of glutathione depletion on apoptosis induced by thiram in Chinese hamster fibroblasts

Fungicide thiram, which is also known as an inducer of allergic contact dermatitis (ACD), was used as a model compound of thiuram chemicals, and its cellular effects were investigated in cultured Chinese hamster V79 cells. The level of intracellular reduced glutathione (GSH), protein sulfhydryl (PSH) groups, protein carbonyls (PC), membrane lipid peroxidation reflected by enhanced thiobarbituric acid reactive substrates (TBARS) production, as well as apoptotic effect were determined. The apoptosis induction was determined by assessing DNA fragmentation by TUNEL, annexin V binding, and caspases activation assays, using fluorescent microscope or flow cytometry, respectively. The concentrations of thiram required to induce cellular GSH depletion (by 40-50%), protein, and membrane lipid peroxidation (2-fold, and 1.7-fold, respectively), as well as to induce apoptosis in V79 Chinese hamster fibroblasts without causing necrosis through cytotoxic effects were between 50-100 microM. To investigate the role of decreased GSH content in the toxicity of thiram, GSH level was modified prior to exposure. Pretreatment of V79 cells with N-acetyl-L-cysteine (NAC), a GSH biosynthesis precursor, prevented GSH decrease, PC and TBARS production, as well as caspases activation induced by thiram exposure. On the other hand, thiram effects were enhanced by the previous depletion of cellular GSH by L-buthionine-(S,R)-sulfoximine (BSO).

Changes in the Tibial Growth Plates of Chickens with Thiram-induced Dyschondroplasia

Tibial dyschondroplasia (TD) is a metabolic cartilage disease of young poultry in which endochondral bone formation is disrupted leading to the retention of a non-calcified, avascular plug of cartilage in the tibial growth plate. Chicks aged 7 days were fed either a control diet or one containing thiram 100 ppm for 48 h to induce TD. Cell multiplication in the growth plate was determined thereafter with bromodeoxyuridine (BrdU) labelling, and metabolic changes by measuring alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP), and glutathione (GSH) activities. The effect on chondrocyte maturation was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of gene expression. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) and DNA fragmentation were used to determine the effects of thiram on cell survival. The results showed that thiram-induced TD was not due to the multiplication of cells in the post-proliferative zones. Thiram did not affect ALP activity, which would have indicated a loss of calcification potential, but it reduced both TRAP and the glutathione concentrations, suggesting that the growth plate metabolism and remodelling functions were adversely affected. Thiram appeared to have no effect on the expression of type X collagen, transglutaminase, RUNX2, or matrix metalloproteinase-2 (MMP) genes suggesting that it did not alter the maturation potential of chondrocytes. On the contrary, the expressions of MMP-13 and vascular endothelial growth factor (VEGF) genes were "up-regulated," suggesting that thiram has pro-angiogenic activity. However, TUNEL assay showed that thiram induced endothelial cell apoptosis in the capillary vessels of the growth plates, as early as 10 days of age, when TD was not visually evident. The vascular death increased on subsequent days accompanied by massive death of chondrocytes in the transition zone of the growth plate. The induction of apoptosis in the growth plate was also demonstrated by DNA fragmentation. It was concluded that thiram induced TD not through an increase in the multiplication of chondrocytes in the transition zone and not by altering the expression of genes causing the arrest of chondrocytes in a prehypertrophic state, but by creating a metabolic dysfunction which led to the destruction of blood capillaries in the transition zone chondrocytes.

Comparative efficacy of different dithiocarbamates to induce tibial dyschondroplasia in poultry

Tibial dyschondroplasia (TD) is a metabolic cartilage disease in poultry the natural etiology of which is not known. In the absence of biomarkers to monitor the initiation and progression of the naturally occurring disease, experimentally induced TD can provide a suitable venue to study the mechanism of its pathogenesis. Therefore, the objective of this study was to establish a streamlined experimental protocol to induce TD using dithiocarbamates and to determine a time course of its progression. Three different dithiocarbamates, dimethyldithiocarbamate, pyrrolidine dithiocarbamate, and tetramethyl thiuram disulfide (thiram), were tested with respect to their abilities to induce TD and affect different physiological factors. Our results show that chickens fed thiram during the first 2 wk of age showed a maximum TD index. Thiram appeared to be the most potent of the 3 dithiocarbamates with dimethyldithiocarbamate having the least ability to induce TD and pyrrolidine dithiocarbamate showing an intermediate potency. A transient exposure to thiram for a day or 2 was sufficient to markedly increase the incidence of TD and produce lasting damage as determined by the presence of severe lesions in a high percentage of birds at 2 to 3 wk after the treatment. Thiram affected the chondrocyte morphology of maturing zone cartilage evident by nuclear shrinkage and emptied chondrocyte lacunae during later times and also involutions of capillary vessels. Such changes were not seen in prehypertrophic zone chondrocytes of the same growth plates. Thiram reduced the BW, increased blood heterophil-to-lymphocyte ratios, and elevated serum corticosterone concentrations indicating physiological stress. However, there was no change in relative liver weights or blood clinical chemistry including the serum concentrations of Ca, P, and Cu in thiocarbamate-fed chickens. Induction of TD in young chickens by means of a short feeding protocol with thiram may be useful to study the mechanisms of pathogenesis of TD and to identify micronutrients that can provide protection against this disease.

Thiram and ziram stimulate non-selective cation channel and induce apoptosis in PC12 cells

The neurotoxicity of dithiocarbamates has been previously reported, however, the detailed mechanism underlying the neurotoxicity is still not fully understood. Among the dithiocarbamates, we investigated thiram and ziram in a neuronal-like pheochromocytoma (PC12) cells. Thiram and ziram strongly induced cell death in both dose- and time-dependent manners with the LC(50) of 0.3 and 2 microM, respectively. The cell death showed typical apoptotic features, such as DNA fragmentation and an increase of subdiploidy nuclei. Interestingly, both thiram and ziram induced rapid and sustained increases of intracellular Ca(2+) in PC12 cells, which were almost completely blocked by flufenamic acid (FFA), an inhibitor of non-selective cation channel. BAPTA-AM, an intracellular Ca(2+) chelator, inhibited the thiram- and ziram-induced apoptotic cell death. These results suggest that thiram and ziram induce apoptotic neuronal cell death by Ca(2+) influx through non-selective cation channels. The present study may provide a clue for understanding the mechanism of neurotoxicity of thiram and ziram.

Thiram-induced cytotoxicity is accompanied by a rapid and drastic oxidation of reduced glutathione with consecutive lipid peroxidation and cell death

The toxic effect of thiram, a widely used dithiocarbamate fungicide, was investigated in cultured human skin fibroblasts. Cell survival assays demonstrated that thiram induced a dose-dependent decrease in the viable cell recovery. Thiram exposure resulted in a rapid depletion of intracellular reduced glutathione (GSH) content with a concomitant increase in oxidized glutathione (GSSG) concentration. Alteration of glutathione levels was accompanied by a dose-dependent decrease in the activity of glutathione reductase (GR), a key enzyme for the regeneration of GSH from GSSG. Thiram-exposed cells exhibited increased lipid peroxidation reflected by enhanced thiobarbituric acid reactive substances (TBARS) production, suggesting that GSH depletion and the lower GR activity gave rise to increased oxidative processes. To investigate the role of decreased GSH content in the toxicity of thiram, GSH levels were modulated prior to exposure. Pretreatment of fibroblasts with N-acetyl-L-cysteine (NAC), a GSH biosynthesis precursor, prevented both lipid peroxidation and cell death induced by thiram exposure. In contrast, thiram cytotoxicity was exacerbated by the previous depletion of cellular GSH by L-buthionine-(S,R)-sulfoximine (BSO). Taken together, these results strongly suggest that thiram induces GSH depletion, leading to oxidative stress and finally cell death.

An evaluation of thiram toxicity on cultured human skin fibroblasts

Thiram is widely used in agriculture as a fungicide and, to a lesser extent, as a vulcanizing agent in the rubber industry. In spite of the extensive use of thiram, knowledge on its toxicity and health risk remains limited, and few investigations have been performed to assess specific damage at the cellular and subcellular level. We report here the cytotoxic effects of thiram on cultured human skin fibroblasts. Our results demonstrated that thiram exposure induced a dose- and time-dependent decrease in the viable cell recovery with 100% cell death observed with a concentration of 5.0 mg/l. As judged by morphological changes and biochemical criteria, thiram-mediated cell death was not of the apoptotic but seemed to be of the necrotic type. This cell death was not associated with a modification of gene expression of different constituents of the extracellular matrix. A late increase of lactate production was evident after thiram treatment, suggesting a mitochondrial metabolic pathway dysfunction as reported by other authors using similar compounds. However, this phenomenon appeared as a secondary response to the toxic action of thiram. The cytotoxic effect of thiram is possibly due to an oxidant effect inherent to the structure of thiram and the interaction between thiram and vital cellular molecules.