interleukin-8 and dimethylarsinous-acid

Chronic exposure to inorganic arsenic (As) is associated with type 2 diabetes, cardiovascular diseases and cancer. Ingested inorganic As is transformed within the gastrointestinal tract and can give rise to more toxic species such as monomethylarsonous acid [MMA(III)] and dimethylarsinous acid [DMA(III)]. Thus, the intestinal epithelium comes into contact with toxic arsenical species, and the effects of such exposure upon epithelial function are not clear. The present study has evaluated the effect of 1 µM arsenite [As(III)], 0.1 µM MMA(III) and 1 µM DMA(III) upon the release of cytokines [interleukin-6 (IL6), IL8, tumor necrosis factor alpha (TNFα)], using a compartmentalized co-culture model with differentiated Caco-2 cells in the apical compartment and peripheral blood mononuclear cells in the basolateral compartment. In addition, the combined effect of arsenical species and lipopolysaccharide (LPS), both added into the apical compartment, has been analyzed. The results indicate that exposure to the arsenical forms induces a proinflammatory response. An increase in cytokine secretion into the basolateral compartment was observed, particularly as regards TNFα (up to 1,600 %). The cytokine levels on the apical side also increased, though to a lesser extent. As/LPS co-exposure significantly affected the proinflammatory response as compared to treatment with As alone. Treatment with DMA(III) and As/LPS co-exposure increased the permeability of the intestinal monolayer. In addition, As/LPS treatments enhanced As(III) and MMA(III) transport through the intestinal monolayer.

Topics: Arsenicals; Arsenites; Caco-2 Cells; Cacodylic Acid; Coculture Techniques; Cytokines; Humans; Interleukin-6; Interleukin-8; Intestinal Mucosa; Leukocytes, Mononuclear; Tumor Necrosis Factor-alpha

Chronic arsenic (As) toxicity in humans has been documented in many countries where exposure mostly occurs through drinking water. The As immunotoxic effects have been demonstrated in animal models as well as in humans. The studies of the immunotoxicity of As have centered on organs related to immune response or target organs, with few data being available at intestinal level. The present study has evaluated the changes in the expression and release of cytokines in Caco-2 cells, widely used as an intestinal epithelial model. Differentiated cells were exposed to 1 μM of As(III), 0.1 μM of monomethylarsonous acid [MMA(III)] and 1 μM of dimethylarsinous acid [DMA(III)] during 2, 4, 6 and 24 h. Additionally, the effect of As coexposure with lipopolysaccharide (LPS, 10 ng/mL) has been evaluated. The results show trivalent species to induce increases in the expression and release of the proinflammatory cytokines tumor necrosis factor alpha (TNFα), IL6, IL8 - the magnitude and time of response being different for each As species. The response of greatest magnitude corresponds to DMA(III), followed by As(III), while MMA(III) generates a limited response. Furthermore, the presence of LPS in the co-exposed cells could affect the expression and secretion of cytokines compared with individual exposure to arsenicals, especially for As(III)/LPS and DMA(III)/LPS.

Topics: Arsenic; Caco-2 Cells; Cacodylic Acid; Cytokines; Humans; Interleukin-6; Interleukin-8; Intestinal Mucosa; Organometallic Compounds; RNA, Messenger; Tumor Necrosis Factor-alpha