Cytotoxic effects of a novel maleimide derivative on epithelial and tumor cells.

Novel N-triazolyl maleimide derivatives were synthesized by azide-alkyne Huisgen cycloaddition (1,3-dipolar cycloaddition) and tested for cytotoxicity against a cell line derived from human melanomas SK-Mel-28 and SK-Mel-103, and human umbilical vein endothelial cell lines (HUVEC). The 4l was chose to be biologically tested due to incorporation of benzyl triazolic to the nitrogen of maleimide has not been tested before, and due the satisfactory yield. The analysis of cell metabolism, using the MTT method, showed that the compound 4l impaired cell metabolism in HUVEC only in high concentration (100µM). A lower concentration of compound 4l, whether in association or not with paclitaxel, was required to cause toxicity in both SK-Mel-28 and SK-Mel-103 cells in comparison with HUVEC cells. Moreover, the ability of 4l to cause cell death was evaluated by flow cytometry, and the data obtained highlighted the apoptotic action of 4l and paclitaxel co-treatment on Sk-Mel-28 cells only, which corroborated the greater efficacy of maleimide compounds against cancer cells. Together, our data provide promising data on the selectivity of maleimide compounds to cancer cells, and suggest that novel maleimide-substituted compounds may be synthesized and tested on different cancer cell lines, as primary or co-adjuvant agents of cancer cell toxicity.

Beneficial effects of vitamin C treatment on pregnant rats exposed to formaldehyde: Reversal of immunosuppression in the offspring.

Inhalation of formaldehyde (FA) during the pregnancy induces oxidative stress in the uterus, and here we hypothesized that this mechanism may be responsible for the impaired immune response detected in the offspring. In order to investigate the protective effects of Vitamin C on the oxidative stress induced by FA in the uterine microenvironment, pregnant Wistar rats were treated with vitamin C (150mg/kg, gavage) or vehicle (distilled water, gavage) 1h before FA exposure (0.92mg/m(3), 1h/day, 5days/week), for 21days, and the 30days old offspring were submitted to LPS injection (Salmonella abortus equi, 5mg/kg, i.p.). The enhanced gene expression of iNOS, COX-1 and COX-2 and decreased gene expression of SOD-2 in the uterus of FA exposed mothers was rescued by Vit C treatment. Moreover, vitamin C rescued the impaired immune response elicited by LPS in the offspring from FA exposed mothers, by increasing the number of blood and bone marrow leukocytes, and augmenting gene expression of IL-6 and reducing mRNA levels of IL-10 and IFN in the lungs. Vitamin C treatment did not rescue the impaired TLR4-NF-kB pathway in the lung of the offspring, suggesting that FA-induced uterine oxidative stress affects other inflammatory pathways activated by LPS in the offspring. Together, data obtained here confirm our hypothesis that FA-induced oxidative stress in the uterine microenvironment modifies the programming mechanisms of the immune defenses of offspring, leading to an impaired host defense.

Hydroquinone, an Environmental Pollutant, Affects Cartilage Homeostasis through the Activation of the Aryl Hydrocarbon Receptor Pathway.

Exposure to environmental pollutants has a proven detrimental impact on different aspects of human health. Increasing evidence has linked pollution to the degeneration of tissues in the joints, although through vastly uncharacterised mechanisms. We have previously shown that exposure to hydroquinone (HQ), a benzene metabolite that can be found in motor fuels and cigarette smoke, exacerbates synovial hypertrophy and oxidative stress in the synovium. To further understand the impact of the pollutant on joint health, here we investigated the effect of HQ on the articular cartilage. HQ exposure aggravated cartilage damage in rats in which inflammatory arthritis was induced by injection of Collagen type II. Cell viability, cell phenotypic changes and oxidative stress were quantified in primary bovine articular chondrocytes exposed to HQ in the presence or absence of IL-1ß. HQ stimulation downregulated phenotypic markers genes SOX-9 and Col2a1, whereas it upregulated the expression of the catabolic enzymes MMP-3 and ADAMTS5 at the mRNA level. HQ also reduced proteoglycan content and promoted oxidative stress alone and in synergy with IL-1ß. Finally, we showed that HQ-degenerative effects were mediated by the activation of the Aryl Hydrocarbon Receptor. Together, our findings describe the harmful effects of HQ on articular cartilage health, providing novel evidence surrounding the toxic mechanisms of environmental pollutants underlying the onset of articular diseases.

Toxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor inhalation on rheumatoid arthritis.

Tobacco combustion exposure worsens rheumatoid arthritis (RA). Non-combustible tobacco devices, as heat-not-burn tobacco (HNBT), are emerging as harm reduction to smokers by releasing nicotine and lower combustible tobacco products. Nevertheless, HNBT toxicity remains unclear. Hence, here we investigated the impacts of the tobacco combustible product (cigarette smoke; CS) or HNBT vapor exposures on antigen-induced arthritis (AIA) in C57BL/6 mice. Animals were exposed to airflow, HNBT vapor, or CS during 1 h/twice a day, under the Health Canada Intense (HCI) smoking regime, between days 14 to 20 after the first immunization. At day 21, 16 h after the last exposures, mice were i.a. challenged and the AIA effects were evaluated 24 h later. CS- or HNBT-exposed mice presented equivalent blood nicotine levels. CS exposure worsened articular symptoms, pulmonary inflammation, and expression of lung metallothioneins. Nevertheless, CS or HNBT exposures reduced lymphoid organs' cellularity, splenocyte proliferation and IL-2 secretion. Additional in vitro CS or HNBT exposures confirmed the harmful effects on splenocytes, which were partially mediated by the activation of nicotine/α7nAchR pathway. Associated, data demonstrate the toxic mechanisms of CS or HNBT inhalation at HCI regime on RA, and highlight that further investigations are fundamental to assure the toxicity of emerging tobacco products on the immune system during specific challenges.

Immunotoxic mechanisms of cigarette smoke and heat-not-burn tobacco vapor on Jurkat T cell functions.

Cigarette smoke (CS) affects immune functions, leading to severe outcomes in smokers. Robust evidence addresses the immunotoxic effects of combustible tobacco products. As heat-not-burn tobacco products (HNBT) vaporize lower levels of combustible products, we here compared the effects of cigarette smoke (CS) and HNBT vapor on Jurkat T cells. Cells were exposed to air, conventional cigarettes or heatsticks of HNBT for 30 min and were stimulated or not with phorbol myristate acetate (PMA). Cell viability, proliferation, reactive oxygen species (ROS) production, 8-OHdG, MAP-kinases and nuclear factor κB (NFκB) activation and metallothionein expression (MTs) were assessed by flow cytometry; nitric oxide (NO) and cytokine levels were measured by Griess reaction and ELISA, respectively. Levels of metals in the exposure chambers were quantified by inductively coupled plasma mass spectrometry. MT expressions were quantified by immunohistochemistry in the lungs and liver of C57Bl/6 mice exposed to CS, HNBT or air (1 h, twice a day for five days: via inhalation). While both CS and HBNT exposures increased cell death, CS led to a higher number of necrotic cells, increased the production of ROS, NO, inflammatory cytokines and MTs when compared to HNBT-exposed cells, and led to a higher expression of MTs in mice. CS released higher amounts of metals. CS and HNBT exposures decreased PMA-induced interleukin-2 (IL-2) secretion and impaired Jurkat proliferation, effects also seen in cells exposed to nicotine. Although HNBT vapor does not activate T cells as CS does, exposure to both HNBT and CS suppressed proliferation and IL-2 release, a pivotal cytokine involved with T cell proliferation and tolerance, and this effect may be related to nicotine content in both products.

Hydroquinone Exposure Worsens Rheumatoid Arthritis through the Activation of the Aryl Hydrocarbon Receptor and Interleukin-17 Pathways.

Rheumatoid arthritis (RA) development is strongly associated with cigarette smoke exposure, which activates the aryl hydrocarbon receptor (AhR) as a trigger for Th17 inflammatory pathways. We previously demonstrated that the exposure to hydroquinone (HQ), one of the major compounds of cigarette tar, aggravates the arthritis symptomatology in rats. However, the mechanisms related to the HQ-related RA still remain elusive. Cell viability, cytokine secretion, and gene expression were measured in RA human fibroblast-like synoviocytes (RAHFLS) treated with HQ and stimulated or not with TNF-α. Antigen-induced arthritis (AIA) was also elicited in wild type (WT), AhR -/- or IL-17R -/- C57BL/6 mice upon daily exposure to nebulized HQ (25ppm) between days 15 to 21. At day 21, mice were challenged with mBSA and inflammatory parameters were assessed. The in vitro HQ treatment up-regulated TNFR1, TNFR2 expression, and increased ROS production. The co-treatment of HQ and TNF-α enhanced the IL-6 and IL-8 secretion. However, the pre-incubation of RAHFLS with an AhR antagonist inhibited the HQ-mediated cell proliferation and gene expression profile. About the in vivo approach, the HQ exposure worsened the AIA symptoms (edema, pain, cytokines secretion and NETs formation) in WT mice. These AIA effects were abolished in HQ-exposed AhR -/- and IL-17R -/- animals though. Our data demonstrated the harmful HQ influence over the onset of arthritis through the activation and proliferation of synoviocytes. The HQ-related RA severity was also associated with the activation of AhR and IL-17 pathways, highlighting how cigarette smoke compounds can contribute to the RA progression.

Hydroquinone exposure worsens the symptomatology of rheumatoid arthritis.

The genesis of rheumatoid arthritis (RA) is complex and dependent on genetic background and exposure to environmental xenobiotic. Indeed, smoking is associated to developing and worsening pre-existing RA. Nevertheless, the mechanisms and cigarette compounds involved in the harmful processes have not been elucidated. Here, we investigated if the exposure to hydroquinone (HQ), an abundant pro-oxidative compound of cigarette and benzene metabolite, could worsen the ongoing RA. Hence, collagen-induced arthritis (CIA) was induced in male Wistar rats by s.c. injection of 400 µg (200 µL) of bovine collagen type II emulsified in complete Freund's adjuvant on day 1, and a booster injection was performed on day 7. Exposures to nebulized HQ (25 ppm), saline solution or HQ vehicle solution (5% ethanol in saline) were carried out for 1 h, once a day, on days 21-27 after CIA induction. On day 27, animals were euthanized and samples were collected for further analyses. Exposure to HQ caused loss of weight, intensified paw edema, enhanced levels of tumor necrosis factor-α (TNF-α) and anti-citrullinated protein antibody (ACPA) in the serum; augmented synoviocyte proliferation and influx of aril hydrocarbon receptor (AhR) positive cells into the synovial membrane, altered collagen fibre rearrangement in the synovia, and synoviocytes isolated from HQ exposed rats secreted higher levels of pro-inflammatory cytokines, TNF-α and interleukin-1ß. Associated, we point out HQ as an environmental pollutant that aggravates RA, suggesting its participation on worsening RA in smoking patients.

In vivo exposure to hydroquinone during the early phase of collagen-induced arthritis aggravates the disease.

Robust correlation between the severity of rheumatoid arthritis (RA) and cigarette smoking has been clinically demonstrated. Nevertheless, cigarette compounds responsible for this toxic effect and their mechanisms have not been described. Considering that hydroquinone (HQ) is an abundant, pro-oxidative compound of the matter particle phase of cigarette smoke, we investigated whether HQ exposure during the initial phase of collagen-induced arthritis (CIA) could aggravate the disease. For this purpose, male Wistar rats were exposed to aerosolized HQ (25 ppm), saline or 5% ethanol solution (HQ vehicle) for 1 h per day during 14 days. CIA was induced through s.c. injection of bovine collagen Type II (0.4 mg/100 µL) at days seven and 14 of exposure. Clinical signs of disease and the cell profile and chemical mediators in the synovial fluid and membrane were analysed at day 35 after the beginning of exposure. HQ exposure aggravated CIA-related paw edema and increased the cell infiltrate and interleukin-6 (IL-6) levels in the synovial fluid, promoted intense tissue collagen deposition and enhanced synoviocyte proliferation and higher frequency of aryl hydrocarbon receptor (AhR+) and interleukin (IL-17+) neutrophils in the synovial membrane. in vitro data also highlighted that neutrophils expressed increased levels of AhR, IL-17 and reactive oxygen species (ROS) generation. However, only AhR expression and ROS generation were blocked by in vitro treatment with AhR antagonist. Therefore, we conclude that in vivo HQ exposure at the early phase of AR onset worsens RA, leading to high frequency of AhR/IL-17+ neutrophils into the joint.

Bothrops jararaca venom gland secretory cells in culture: Effects of noradrenaline on toxin production and secretion.

Primary culture of snake venom gland secretory cells could be a good model to study the mechanism(s) of toxin(s) production. These cells can produce and secrete venom to the medium with a hemorrhagic activity comparable to that induced by venom collected from snakes. Production of new venom is triggered by the sympathetic outflow, through the release of noradrenaline, but the importance of this neurotransmitter on toxin synthesis has not been addressed. This work led to the identification and comparison of the toxin panel produced by cultured secretory cells, during a 12-day time-course analysis, as well as to the effects of noradrenaline on the process. The results showed that in our culture model the synthesis of new toxins is asynchronous, mimicking data previously published from proteomic analyses of venom glands harvested from animal experimentation. Furthermore, noradrenaline did regulate the synthesis and/or secretion of venom toxins over the analyzed period. Finally, we demonstrated that snake venom metalloproteinases present in these cultured cells secretome were mostly in their zymogen forms; consequently, processing occurs after secretion to the gland lumen. Overall, the data support the use of venom gland secretory cells as a reliable model to investigate the mechanism(s) of toxin(s) synthesis and secretion.

Papel da exposição à Hidroquinona na artrite reumatoide experimental induzida pelo colágeno / Role of Hydroquinone exposure on experimental collagen-induced arthritis

Artrite reumatoide (AR) é uma doença autoimune, que causa inflamação crônica nas membranas sinoviais de diversas articulações. O modelo experimenal de artrite induzida pelo colágeno (AIC) é empregado para investigar os mecanismos da AR e para identificar potenciais agentes terapêuticos. Embora a etiologia da AR ainda seja desconhecida, há evidências que a AR se desenvolve em indivíduos predispostos geneticamente, após exposição a fatores ambientais, como o tabagismo, que se destaca como maior fator de risco para indução da AR e para o agravamento em pacientes com AR já estabelecida. Porém, o mecanismo efetivo da ação dos diversos componentes do cigarros ainda precisa ser elucidado. A Hidroquinona (HQ) é um composto fenólico, encontrada em concentração elevada no cigarro, com maior ativade pró-oxidativa, além de ser produto da biotransformação do benzeno, também encontrado no cigarro. Neste caso, a HQ é responsável pela imunotoxicidade e mielotoxicidade do benzeno. Devido a alta exposição de fumantes à HQ e a associação do tabagismo com a AR, investigamos se a exposição à HQ teria participação no desenvolvimento da AIC em ratos Wistar. Para tanto, animais foram expostos à HQ em diferentes protocolos experimentais, a saber: A - por 35 dias consecutivos, durante fase de indução e desenvolvimento da artrite; B - por 14 dias consecutivos, até a segunda injeção de colágeno, na fase de sensibilização e indução da AIC; C - por 7 dias consecutivos, do 29º ao 35º dia, na fase posterior ao desenvolvimento da AIC. Os resultados obtidos mostraram que a HQ agravou a AR nos 3 grupos experimentais, aumentando os parâmetros clínicos, o número de células no líquido sinovial, a inflamação nas sinóvias, caracterizada por maior influxo de neutrófilos, proliferação de sinoviócitos (histologia por HE e imunohistoquímica), aumento nos níveis de IL-6 e IL-1ß (ELISA) no líquido sinovial e rearranjo do colágeno na sinóvia (microscopia por segundo harmônico). No entanto, os efeitos mais acentuados foram observados em animais dos grupos A e C, que também tiveram perda de peso significativa. Ademais, exposição à HQ, nos 3 grupos experimentais, causou expressão aumentada do receptor aril hidrocarboneto (AhR), um receptor ativado por xenobióticos durante a AR, e aumento nos níveis do fator de transcrição ROR e de IL-17 na sinóvia. Como AhR/ROR/IL-17 em linfócitos e neutrófilos é uma via importante na gênese da AR, ensaios in vitro foram realizados para elucidar o papel da HQ nesta via. A incubação com HQ in vitro de esplenócitos de animais naive elevou a expressão de AhR e de secreção de IL-17 (por citometria de fluxo), as quais foram bloqueadas pelo antagonista de AhR (α-naftoflavona). Em conjunto, os resultados obtidos nos permitem concluir que a HQ, como um importante componente do cigarro agrava a CIA em ratos, e a ativação via AhR/IL-17 é um possível mecanismo da patogênese da artrite

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in the joint synovial membranes. The experimental model of collagen-induced arthritis (CIA) is used to investigate the involved mechanisms in RA and to identify novel therapeutic agents. The genesis of RA is multifactorial, involving interplay of genetic and environmental factors and smoking is the trigger factor in the development or RA and worsens the pre-existing RA but the mechanisms undlerlying are yet to be elucidated. Hydroquinone (HQ) is a phenolic compound, found in high concentrations in cigarette, where HQ is the major oxidative component. Moreover, HQ is benzene metabolite, which is also found in cigarette smoke, being responsible for the myelotoxicity and immunotoxicity detected during benzene exposure. Due to this association, we aimed to investigate the role of HQ exposure on CIA development in Wistar rats and the involved mechanisms. Animals were exposed to HQ according to different protocols: A - during 35 consecutive days, during the sensitization and devolpment phases of the disease; B - during 14 consecutive days, until the second injection of collagen, during the sensitization phase; C - during 7 consecutive days, from day 29 to 35, after the development phase of CIA. The results showed that HQ worsened the RA in the 3 experimental protocols, HQ elevated the clinical parameters of CIA development, increased inflammation in the synovial membrane, characterized by increased influx of neutrophis, synoviocytes proliferation (visualized by Immunohistochemistry and Histology analysis), augmented the levels of IL-6 and IL-1ß in the synovial fluid (ELISA assay) and led to intense collagen deposition on the synovia. The most pronounced effects where observed in animals from groups A and C, which also had weight body loss. In addition, in the 3 protocols, HQ exposure also increased the expression of AhR receptor, a receptor activated by xenobiotics during RA, and increased the expression of ROR and levels of IL-17 secretion in the synovial membranes. As AhR/ROR/IL-17 in lymphocytes and neutrophils is an important pathway involved in the genesis of RA, in vitro studies have been performed to elucidate the role of HQ exposure in this pathway. The HQ in vitro treatment augmented the expression of AhR and secretion of IL-17 by splenocytes (FACS assay) and the administration of an AhR antagonist (α-naphtoflavone) blocked these effects. Taken together, the results obtained here allow us to conclude that HQ, as an important cigarette component, aggravates CIA in rats, and the activation of AhR/IL-17 pathway is a possible mechanism involved in the RA pathogenesis