Biomarkers of effects: The immune system

Immune response of Brazilian farmers exposed to multiple pesticides

Occupational exposure to pesticides has been identified as a factor that predisposes to disorders of the immune system. Immunosuppression, autoimmunity, cancer of various organs and other diseases in people who apply these products have been reported by the studies. This study aimed to investigate the relationship between occupational exposure to pesticides and the immunological profile in 43 farmers exposed to mixtures of pesticides for at least 15 years. A control group composed of 30 individuals without a history of occupational exposure to pesticides was also evaluated. Peripheral blood samples were processed by flow cytometry and cells were labelled with an 8-color monoclonal antibody panel. Plasma cytokines were also measured. Significant increase in classical monocytes (p < 0.001) and dendritic cells (p < 0.001) in the exposed group was observed as well in total T cells (p = 0.04), central memory CD8 T cells (p = 0.02) and effector memory CD8 T cells (p = 0.01). On the other hand, the activation markers of T cells as the expression of CD57, HLA-DR, CD25 and CD28 were evaluated and no difference was found between groups. When the B cells were analyzed, a significant decrease in total B cells (p = 0.01), regulatory B cells (p < 0.001) and plasmablasts (p < 0.001) in the exposed group, compared to healthy controls, was observed. Pro-inflammatory IL-6 was significantly elevated (p = 0.04) in the plasma of farmers compared to that of controls. The constant antigenic stimulus that occurs during exposure to pesticides can favor the recruitment of dendritic cells and macrophages (APCs) presents in the skin and respiratory tract. In the secondary lymphoid organs, the CD4 T and B cells that process such antigens are possibly undergoing proliferative exhaustion, with the consequent depletion of all mature B subpopulations. The resulting drop in humoral immunity may be offset by an increase in the number of circulating CD8 T lymphocytes due to their cytotoxic action.

Genotoxic potency of mercuric chloride in gill cells of marine gastropod Planaxis sulcatus using comet assay

In vivo and in vitro exposures were used to investigate the genotoxicity of mercuric chloride (HgCl2) to the marine snail, Planaxis sulcatus. The comet assay protocol was validated on gill cells exposed in vitro to hydrogen peroxide (H2O2, 0-50 μM). Snails were exposed in vivo for 96 h to HgCl2 (10, 20, 50, and 100 μg/l). Our results showed significant concentration-dependent increase in the tail DNA (TDNA) and olive tail moment (OTM) in exposed snails for all doses compared with controls. In vitro exposure to HgCl2 (10-100 μg/l) resulted in significantly higher values for TDNA at all concentrations. Our results showed that DNA damage increased in the gill cell with increasing exposure time. This study demonstrates the usefulness of comet assay for detection of DNA damage after exposure to HgCl2 and the sensitivity of marine snail P. sulcatus as a good candidate species for metal pollution.

Multiple experimental approaches of immunotoxic effects of mercury chloride in the blue mussel, Mytilus edulis, through in vivo, in tubo and in vitro exposures

Biological impairments due to mercury discharge into the environment are now an issue of global concern. From the three forms of mercury found in aquatic ecosystems, the immunotoxic effects of mercury chloride were examined in the model animal, the blue mussel. In order to investigate the toxic potency of this chemical, three exposure regimes were carried out: chronic exposure of groups of individuals, a new protocol "in tubo" designed for sub-acute exposures of individuals, and acute exposures of target cells. Chronic exposure revealed significant immunotoxic effects after 7 days at 10(-6)M, while acute exposures showed significant inhibition of phagocytosis at 10(-4)M and 10(-3)M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10(-4)M and 10(-3)M while phagocytosis and the clearance rate drew hormetic toxic effects on healthy individuals. These results suggest the use of the "in tubo" design for bivalve toxicological individual studies.

Our genes are not our destiny: incorporating molecular medicine into clinical practice

In many developed nations, the state of publicly administered health care is increasingly precarious as a result of escalating numbers of chronically ill patients, inadequate medical personnel and hospital facilities, as well as sparse funding for ongoing upgrades to state-of-the-art diagnostic and therapeutic technology - an increased emphasis on aetiology-centred medicine should be considered in order to achieve improved health for patients and populations. Medical practice patterns which are designed to provide quick and effective amelioration of signs and symptoms are frequently not an enduring solution to many health afflictions and chronic disease states. Recent scientific discovery has rendered the drug-oriented algorithmic paradigm commonly found in contemporary evidence-based medicine to be a reductionist approach to clinical practice. Unfolding evidence appears to support a genetic predisposition model of health and illness rather than a fatalistic predestination construct - modifiable epigenetic and environmental factors have enormous potential to influence clinical outcomes. By understanding and applying fundamental clinical principles relating to the emerging fields of molecular medicine, nutrigenomics and human exposure assessment, doctors will be empowered to address causality of affliction when possible and achieve sustained reprieve for many suffering patients.

Carcinogenicity of agricultural pesticides in adults and children

The role of specific agricultural pesticides in relation to adult and childhood cancers has not been firmly established due to the lack of precise exposure data in previous studies. Improvements in exposure assessment, disease classification, and application of molecular techniques in recent epidemiological evaluations is rapidly improving our ability to evaluate the human carcinogenicity of agricultural pesticides. The role of pesticide exposures in the etiology of human cancer is outlined by anatomical site and recent development in exposure assessment and molecular epidemiology are summarized and evaluated.