Search

The complex immune system displays a coordinated transcriptional response to xenobiotic exposure by altering expression of designated transcription factors that, in turn, trigger immune responses. Despite the identification of several transcription factors that contribute to regulatory response, very little is known about the specific role of factors that are triggered due to exposure to obnoxious pesticides. Here, for the first time, alterations in human peripheral blood lymphocyte expression of transcriptional factors - thrombospondin-1 (THBS-1), secretory phospho-protein-1 (SPP-1), glycoprotein non-metastatic-β (GPNMB) and fasciculation and elongation factor ζ-1 (FEZ-1), due to in vitro exposure to the crop protection chemicals cypermethrin and mancozeb are reported. Results revealed significant changes in expression profiles due to mancozeb exposure, supporting its immune dysfunction potential; in contrast, cypermethrin exposure did not cause significant changes. Based on these effects on gene expression across the doses tested, it was likely key components of immune mechanisms such as proliferation, cell adhesion, apoptosis and cell activation in human PBMC were affected. Although these data are from in vitro experiments, the results point out the potential role for changes in these factors in the etiology of defective T-cell immune function seen in humans occupationally exposed to crop protection chemicals like mancozeb. These studies suggest the involvement of transcription factors in regulation of pesticide-induced immune dysfunction; these studies also represent a novel approach for identifying potential immune-related dysfunctions due to exposure to pesticides. Further studies are needed to better understand the functional significance of these in vitro findings.

In the past two decades, hematologic and immunologic disorders in humans have been increasingly reported as a result of pesticide exposures. Therefore, safety assessment is required to assess the effects on hematopoiesis and thus on the immune system in addition to routine toxicity evaluation. Currently, the data available on effects of pesticides on hematopoiesis in humans is limited. In the study here, cypermethrin and mancozeb were evaluated for their possible effects on hematopoiesis in vitro. Hematopoietic stem or progenitor cells from human cord blood were isolated and then exposed for 14 days to cypermethrin or mancozeb at non-cytotoxic doses (0.9-16 µM), and the effect on hematopoiesis screened via a methylcellulose-based clonogenic assay. Results indicated there were significant concentration-related decreases in clonogenic potentials of erythroid and granulocyte-macrophage colony formation. The inhibitory concentration (IC50) value with erythroid progenitors for cypermethrin was 8.7 [± 0.2 µM; mean [± SE]) and for mancozeb 6.2 [± 0.2] µM. Similarly, IC50 values with granulocyte-macrophage progenitors for cypermethrin and mancozeb were 19.2 [± 1.0] and 8.1 [± 0.2] µM, respectively. These data suggest that erythroid progenitors are perhaps more sensitive to these pesticides. Still, further studies are needed to understand the functional significance of these in vitro findings. For now, these data, albeit preliminary, emphasize the need to include an expanded battery of tests to understand effects on immune parameters in pre-clinical safety studies with pesticides. This study also emphasizes the utility of human cord blood in assessing potential effects on hematopoiesis in vitro.

In recent times, human cell-based assays are gaining attention in assessments of immunomodulatory effects of chemicals. In the study here, the possible effects of cypermethrin and mancozeb on lymphocyte proliferation and proinflammatory (tumor necrosis factor (TNF-)α) and immunoregulatory cytokine (interferon- (IFN-)γ, interleukins (IL) 2, 4, 6, and 10) formationin vitrowere investigated. Human peripheral blood mononuclear cells (PBMC) were isolated and exposed for 6 hr to noncytotoxic doses (0.45–30 µM) of cypermethrin or mancozeb in the presence of activating rat S9 fraction. Cultures were then further incubated for 48 or 72 hr in fresh medium containing phytohemagglutinin (10 µg/mL) to assess, respectively, effects on cell proliferation (BrdU-ELISA method) and cytokine formation (flow cytometric bead immunoassays). Mancozeb induced dose-dependent increases in lymphocyte proliferation, inhibition of production of TNFαand theTH2 cytokines IL-6 and IL-10, and an increase in IFNγ(TH1 cytokine) production (at least 2-fold compared to control); mancozeb also induced inhibition of IL-4 (TH2) and stimulated IL-2 (TH1) production, albeit only in dose-related manners for each. In contrast, cypermethrin exposure did not cause significant effects on proliferation or cytokine profiles. Further studies are needed to better understand the functional significance of ourin vitrofindings.

Biological network models offer a framework for understanding disease by describing the relationships between the mechanisms involved in the regulation of biological processes. Crowdsourcing can efficiently gather feedback from a wide audience with varying expertise. In the Network Verification Challenge, scientists verified and enhanced a set of 46 biological networks relevant to lung and chronic obstructive pulmonary disease. The networks were built using Biological Expression Language and contain detailed information for each node and edge, including supporting evidence from the literature. Network scoring of public transcriptomics data inferred perturbation of a subset of mechanisms and networks that matched the measured outcomes. These results, based on a computable network approach, can be used to identify novel mechanisms activated in disease, quantitatively compare different treatments and time points, and allow for assessment of data with low signal. These networks are periodically verified by the crowd to maintain an up-to-date suite of networks for toxicology and drug discovery applications.

In recent times, human cell-based assays are gaining attention in assessments of immunomodulatory effects of chemicals. In the study here, the possible effects of cypermethrin and mancozeb on lymphocyte proliferation and proinflammatory (tumor necrosis factor (TNF-) α) and immunoregulatory cytokine (interferon- (IFN-) γ, interleukins (IL) 2, 4, 6, and 10) formation in vitro were investigated. Human peripheral blood mononuclear cells (PBMC) were isolated and exposed for 6 hr to noncytotoxic doses (0.45–30 µM) of cypermethrin or mancozeb in the presence of activating rat S9 fraction. Cultures were then further incubated for 48 or 72 hr in fresh medium containing phytohemagglutinin (10 µg/mL) to assess, respectively, effects on cell proliferation (BrdU-ELISA method) and cytokine formation (flow cytometric bead immunoassays). Mancozeb induced dose-dependent increases in lymphocyte proliferation, inhibition of production of TNFα and the TH2 cytokines IL-6 and IL-10, and an increase in IFNγ (TH1 cytokine) production (at least 2-fold compared to control); mancozeb also induced inhibition of IL-4 (TH2) and stimulated IL-2 (TH1) production, albeit only in dose-related manners for each. In contrast, cypermethrin exposure did not cause significant effects on proliferation or cytokine profiles. Further studies are needed to better understand the functional significance of our in vitro findings.