Synthesis of interleukin 1 beta and interleukin 6 in human lymphocytes is stimulated by tributyltin

Interleukin 1β and interleukin 6 production in human immune cells is stimulated by the antibacterial compound Triclosan

Triclosan (TCS) is an antimicrobial compound widely used in personal hygiene products such as mouthwash and toothpaste; and has been found in human blood, breast milk, and urine. Interleukin (IL)-6 and IL-1 beta (IL-1β) are pro-inflammatory cytokines regulating cell growth, tissue repair, and immune function; increased levels of each have been associated with many diseases, including cancer. Previous studies showed that TCS at concentrations between 0.05 and 5 µM consistently increased the secretion of IL-1β and IL-6 from human immune cells within 24 h of exposure. The current study demonstrates that this increase in secretion was not due simply to release of existing stores but was due to an increase in cellular production/levels (both secreted and intracellular levels) of each of these cytokines. Production of IL-1β and IL-6 was increased by exposure to one or more concentration of TCS at each length of exposure (10 min, 30 min, 6 h, and 24 h). TCS-induced stimulation of cytokine production was shown to be dependent on the mitogen-activated protein kinase (MAPK) p44/42 (ERK 1/2). It was also shown that these TCS-induced increases in IL-1β and IL6 production were accompanied by increased mRNA for IL-1β and IL-6. The ability of TCS to increase production indicates that rather than activating a self-limiting process of depleting cells of already existing stores of IL-1β or IL-6, TCS can stimulate a process that has the capacity to provide sustained production of these cytokines and thus may lead to chronic inflammation and its pathological consequences.

Environmental Health and Toxicology: Immunomodulation Promoted by Endocrine-Disrupting Chemical Tributyltin

Tributyltin (TBT) is an environmental contaminant present on all continents, including Antarctica, with a potent biocidal action. Its use began to be intensified during the 1960s. It was effectively banned in 2003 but remains in the environment to this day due to several factors that increase its half-life and its misuse despite the bans. In addition to the endocrine-disrupting effect of TBT, which may lead to imposex induction in some invertebrate species, there are several studies that demonstrate that TBT also has an immunotoxic effect. The immunotoxic effects that have been observed experimentally in vertebrates using in vitro and in vivo models involve different mechanisms; mainly, there are alterations in the expression and/or secretion of cytokines. In this review, we summarize and update the literature on the impacts of TBT on the immune system, and we discuss issues that still need to be explored to fill the knowledge gaps regarding the impact of this endocrine-disrupting chemical on immune system homeostasis.

Increased hepatic interleukin-1, arachidonic acid, and reactive oxygen species mediate the protective potential of peptides shared by gut cysteine peptidases against Schistosoma mansoni infection in mice

BACKGROUND

Multiple antigen peptide (MAP) construct of peptide with high homology to Schistosoma mansoni cathepsin B1, MAP-1, and to cathepsins of the L family, MAP-2, consistently induced significant (P < 0.05) reduction in challenge S. mansoni worm burden. It was, however, necessary to modify the vaccine formula to counteract the MAP impact on the parasite egg counts and vitality, and discover the mechanisms underlying the vaccine protective potential.

METHODOLOGY

Outbred mice were immunized with MAP-2 in combination with alum and/or MAP-1. Challenge infection was performed three weeks (wks) after the second injection. Blood and liver pieces were obtained on an individual mouse basis, 23 days post-infection (PI), a time of S. mansoni development and feeding in the liver before mating. Serum samples were examined for the levels of circulating antibodies and cytokines. Liver homogenates were used for assessment of liver cytokines, uric acid, arachidonic acid (ARA), and reactive oxygen species (ROS) content. Parasitological parameters were evaluated 7 wks PI.

PRINCIPAL FINDINGS

Immunization of outbred mice with MAP-2 in combination with alum and/or MAP-1 elicited highly significant (P < 0.005) reduction of around 60% in challenge S. mansoni worm burden and no increase in worm eggs' loads or vitality, compared to unimmunized or alum pre-treated control mice. Host memory responses to the immunogens are expected to be expressed in the liver stage when worm feeding and cysteine peptidases release start to be active. Serum antibody and cytokine levels were not significantly different between control and vaccinated mouse groups. Highly significant (P < 0.05 - <0.0001) increase in liver interleukin-1, ARA, and ROS content was recorded in MAP-immunized compared to control mice.

CONCLUSION/SIGNIFICANCE

The findings provided an explanation for the gut cysteine peptidases vaccine-mediated reduction in challenge worm burden and increase in egg counts.

Organotin and organochlorine toxicants activate key translational regulatory proteins in human immune cells

Environmental contaminant exposures occur due to the widespread use of synthetic chemicals. Tributyltin (TBT), dibutyltin (DBT), and pentachlorophenol (PCP) are each used in a variety of applications, including antifouling paints and stabilizers in certain plastics. Each of these compounds has been found in human blood, as well as other tissues, and they have been shown to stimulate pro-inflammatory cytokine production in human immune cells, Inflammatory cytokines mediate response to injury or infection. However, if their levels are increased in the absence of an appropriate stimulus, chronic inflammation can occur. Chronic inflammation is associated with a number of pathologies including cancer. Stimulation of pro-inflammatory cytokine production by these toxicants is dependent on activation of ERK 1/2 and/or p38 MAPK pathways. MAPK pathways have the capacity to regulate translation by increasing phosphorylation of key translation regulatory proteins. There have been no previous studies examining the effects of TBT, DBT, or PCP on translation. The current study shows that ribosomal protein S6 (S6), eukaryotic initiation factor 4B (eIF4B), and eIF4E are phosphorylated (activated) and/or their total levels are elevated in response to each of these compounds at concentrations found in human blood. Activation/increased levels of translational proteins occurred at concentrations of the compounds that have been shown to elevate pro-inflammatory cytokine production, but where there is no increase in mRNA for those proteins was seen. Compound-stimulated increases in translation appear to be part of the mechanism by which they elevate protein production in immune cells.

Toll-like receptors in the mechanism of tributyltin-induced production of pro-inflammatory cytokines, IL-1β and IL-6

Tributyltin (TBT) is an environmental contaminant due to its use in a variety of applications as a biocide, including in marine anti-fouling paints. It has been detected in a number of human tissues including blood. Previous studies have shown that exposure to TBT increases the cellular production (secretion plus intracellular levels) of the pro-inflammatory cytokines IL-1β and IL-6 by peripheral blood mononuclear cells (PMBCs) and this increase requires MAPK activation. Toll-like receptors (TLR) activate immune cells to produce pro-inflammatory cytokines in response to pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) leading to activation of MAPKs as well as other intracellular components that regulate cytokine production. The current study shows that selective inhibition of TLRs 4,1/2, and 8 diminishes the ability of TBT to stimulate IL-1β and IL-6 production. However, selective inhibition of TLR3 enhanced the TBT-induced production of IL-1β. This indicates that TBT may be either directly or indirectly interacting with certain TLR receptors as part of its mechanism of stimulating pro-inflammatory cytokine production. These results provide an important advance in understanding TBT stimulation of IL-1β and IL-6, which has the potential to cause chronic inflammation and its attendant pathologies.

Endocrine Disruptor Compounds-A Cause of Impaired Immune Tolerance Driving Inflammatory Disorders of Pregnancy?

Endocrine disrupting compounds (EDCs) are prevalent and ubiquitous in our environment and have substantial potential to compromise human and animal health. Amongst the chronic health conditions associated with EDC exposure, dysregulation of reproductive function in both females and males is prominent. Human epidemiological studies demonstrate links between EDC exposure and infertility, as well as gestational disorders including miscarriage, fetal growth restriction, preeclampsia, and preterm birth. Animal experiments show EDCs administered during gestation, or to either parent prior to conception, can interfere with gamete quality, embryo implantation, and placental and fetal development, with consequences for offspring viability and health. It has been presumed that EDCs operate principally through disrupting hormone-regulated events in reproduction and fetal development, but EDC effects on maternal immune receptivity to pregnancy are also implicated. EDCs can modulate both the innate and adaptive arms of the immune system, to alter inflammatory responses, and interfere with generation of regulatory T (Treg) cells that are critical for pregnancy tolerance. Effects of EDCs on immune cells are complex and likely exerted by both steroid hormone-dependent and hormone-independent pathways. Thus, to better understand how EDCs impact reproduction and pregnancy, it is imperative to consider how immune-mediated mechanisms are affected by EDCs. This review will describe evidence that several EDCs modify elements of the immune response relevant to pregnancy, and will discuss the potential for EDCs to disrupt immune tolerance required for robust placentation and optimal fetal development.

Dibutyltin alters immune cell production of the pro-inflammatory cytokines interleukin (IL) 1β and IL-6: role of mitogen-activated protein kinases and changes in mRNA

Dibutyltin (DBT) is used to stabilize plastics and as a deworming agent in some poultry. It is found in human blood (levels as high as 0.3 μM). Interleukin (IL) 1β (IL-1β) and IL-6 are pro-inflammatory cytokines produced by lymphocytes, monocytes, and other cells. Elevated levels of IL-1β and IL-6 have been associated with pathologies including rheumatoid arthritis and cancers. DBT was shown to decrease IL-1β and IL-6 secretion from immune cells at higher concentrations while causing increases at lower concentrations. However, it was not clear if these changes were due to DBT's alteration of the secretory process or due its ability to change cellular synthesis/production of these proteins. This study addresses this question, as well as mechanisms for any observed changes in synthesis/production. Monocyte-depleted peripheral blood mononuclear cells (MD-PBMCs) were exposed to DBT at concentrations of 5, 2.5, 1, 0.5, 0.25, 0.1, and 0.05 μM for 1, 6, and 24 h and the production (combination of secreted and intracellular levels from the same cells) of both IL-1β and IL-6 were measured. Effects of selected DBT exposures on cytokine production were also examined in PBMCs and DBT's effects were similar when monocytes were present. The 24-h exposures to DBT decreased production of both IL-1β and IL-6 at the two highest concentrations but increased production at lower concentrations. Both decreases and increases in cytokine production appear to be explained by DBT-induced changes in mRNA levels. DBT-induced increases in cellular production of the cytokines appear to require p38 and ERK1/2 MAPK pathways.

NF-κB blockade during short-term l-NAME and salt overload strongly attenuates the late development of chronic kidney disease

Nitric oxide synthase inhibition by N^ω-nitro-l-arginine methyl ester (l-NAME) plus a high-salt diet (HS) is a model of chronic kidney disease (CKD) characterized by marked hypertension and renal injury. With cessation of treatment, most of these changes subside, but progressive renal injury develops, associated with persistent low-grade renal inflammation. We investigated whether innate immunity, and in particular the NF-κB system, is involved in this process. Male Munich-Wistar rats received HS + l-NAME (32 mg·kg^-1·day^-1), whereas control rats received HS only. Treatment was ceased after week 4 when 30 rats were studied. Additional rats were studied at week 8 (n = 30) and week 28 (n = 30). As expected, HS + l-NAME promoted severe hypertension, albuminuria, and renal injury after 4 wk of treatment, whereas innate immunity activation was evident. After discontinuation of treatments, partial regression of renal injury and inflammation occurred, along with persistence of innate immunity activation at week 8. At week 28, glomerular injury worsened, while renal inflammation persisted and renal innate immunity remained activated. Temporary administration of the NF-κB inhibitor pyrrolidine dithiocarbamate, in concomitancy with the early 4-wk HS + l-NAME treatment, prevented the development of late renal injury and inflammation, an effect that lasted until the end of the study. Early activation of innate immunity may be crucial to the initiation of renal injury in the HS + l-NAME model and to the autonomous progression of chronic nephropathy even after cessation of the original insult. This behavior may be common to other conditions leading to CKD.

The organochlorine pesticides pentachlorophenol and dichlorodiphenyltrichloroethane increase secretion and production of interleukin 6 by human immune cells

The environmental contaminants pentachlorophenol (PCP) and 4, 4'-dichlorodiphenyltrichloroethane (DDT) are detected in some human blood samples at levels as high as 5 μM (PCP) and 260 nM (DDT). Several cancers are associated with exposures to these contaminants. IL-6 is a pro-inflammatory cytokine that when dysregulated stimulates inflammatory diseases and tumor progression. Immune cells exposed to PCP at 0.05-5 μM and DDT at 0.025-2.5 μM showed increased secretion of IL-6 when the cell preparations contained either T lymphocytes or monocytes. Increased IL-6 secretion was due to PCP and DDT induced cellular production of the cytokine and was dependent on MAP kinase signaling pathways (in the case of PCP). Compound-induced increases in IL-6 production were in part due to increases in either the transcription of and/or stability of its mRNA. Thus, both PCP and DDT have the potential to produce chronic inflammation by stimulating production of IL-6 by immune cells.

Immunomodulatory effects of synthetic endocrine disrupting chemicals on the development and functions of human immune cells

Endocrine disrupting chemicals (EDCs) are added to food, cosmetics, plastic packages, and children's toys and have thus become an integral part of the human environment. In the last decade, there has been increasing interest in the effect of EDCs on human health, including their impact on the immune system. So far, researchers have proved that EDCs (e.g. bisphenols, phthalates, triclosan, phenols, propanil, tetrachlorodibenzo-p-dioxin, diethylstilbestrol, tributyltin (TBT), and parabens) affect the development, functions, and lifespan of immune cells (e.g., monocytes, neutrophils, mast cells, eosinophils, lymphocytes, dendritic cells, and natural killers). In this review, we have summarized the current knowledge of the multivariable influence of EDCs on immune cells and underlined the novel approach to EDC studies, including dose-dependent effects and low-dose effects. We discuss critically the possible relationship between exposure to EDCs and immunity related diseases (e.g. allergy, asthma, diabetes, and lupus). Moreover, based on the literature, we construct a model of possible mechanisms of EDC action on immune cells at cellular, molecular, and epigenetic levels.

Exposures to the environmental contaminants pentachlorophenol and dichlorodiphenyltrichloroethane increase production of the proinflammatory cytokine, interleukin-1β, in human immune cells

Pentachlorophenol (PCP) and dichlorodiphenyltrichloroethane (DDT) are organochlorine environmental contaminants found in human blood at very significant levels (as high as 5 μm for PCP and 260 nm for DDT). Cancers of the blood (lymphoma and myeloma) and kidney as well as others have been associated with exposure to these contaminants. Interleukin (IL)-1β is a proinflammatory cytokine and is involved in stimulating cell proliferation. High levels of IL-1β are associated with inflammatory diseases and tumor progression. Previous studies showed that PCP and DDT at certain concentrations were able to stimulate secretion of IL-1β. This study shows that the increased secretion of IL-1β seen with both contaminants is due to compound-induced increases in the production of this cytokine. Increased production began within 6 hours of exposure to PCP and continued to increase up to 24 hours. DDT-induced stimulation of IL-1β appeared to be maximal after 6 hours of exposure and then diminished by 24 hours. The increases seen in IL-1β production stimulated by PCP appear to be at least partially due to compound-induced increases in IL-1β mRNA. Although DDT caused increased production of IL-1β, it did not appear to cause consistent increases in its mRNA. PCP- and DDT-induced increases in IL-1β production were dependent primarily on the p38 mitogen-activated protein kinase pathway. These results indicate that both PCP and DDT are able to increase IL-1β production in a p38 mitogen-activated protein kinase-dependent manner, which may have the potential to influence chronic inflammation.