Evaluating macrophages in immunotoxicity testing

Rhamnogalacturonan I-rich polysaccharide isolated from fermented persimmon fruit increases macrophage-stimulatory activity by activating MAPK and NF-κB signaling

BACKGROUND

Persimmon (Diospyros kaki) is a familiar and widespread fruit, cultivated worldwide. To date, physiological and chemical changes in fermented persimmon fruit and its active compounds have been rarely investigated. Moreover, comparative studies on the pharmacological activities of fermented persimmon fruit-derived compounds have not been reported.

RESULTS

To investigate the effect of traditional fermented foods on immunostimulatory activity, non-fermented persimmon fruit (D. kaki, DK) and fermented persimmon fruit (fermented D. kaki, FDK) were prepared and further fractionated into low- and high-molecular weight fractions. FDK exhibited significantly higher activity toward the production of macrophage-stimulatory mediators compared with that of DK, and the high-molecular weight fraction (FDK-H) isolated from FDK was shown to have more potent activity than FDK. FDK-H not only increased the expression of immunostimulatory genes (TNF-α, IL-6, IL-12, and iNOS), but also stimulated the phosphorylation of both MAPK (ERK, JNK, and p38) and NF-κB (p65 and IκB) signaling molecules underlying macrophage activation. The putative chemical characteristic of FDK-H was identified as a pectic rhamnogalacturonan (RG) I-rich polysaccharide with a high molecular weight of 304 kDa containing galacturonic acid, arabinose, rhamnose, and galactose as the major monosaccharide units.

CONCLUSION

The present study reveals that traditional fermentation is a useful method for increasing the macrophage-immunostimulatory activity of persimmon fruit, and the increased activity may be associated with structural modification of persimmon polysaccharides. This study may serve to identify a functional ingredient as an immunostimulatory agent, and our results may be applied to develop a new immunostimulatory product using FDK-H. © 2021 Society of Chemical Industry.

Pesticide dichorvos induces early solid Ehrlich tumoral development associated with a non-protective pro-inflammatory response

Prolonged exposure to dichlorvos (DDVP), a common pesticide used for food crops, has been related to the development of infections and malignancies. Macrophages are used as bioindicators of immunotoxicity; thus, evaluation of their activity in solid Ehrlich tumor-bearing mice (TBM) may be useful to evaluate the influence of pesticides on human health. To investigate the effects of low DDVP doses, Swiss mice were divided into the following groups: the DDVP group, composed of mice fed diets containing 10 mg/kg of DDVP; the TBM group, consisting of mice subcutaneously inoculated with 10⁷ tumor cells/100 μl and fed a basal diet; the DDVP-TBM group, consisting of mice previously fed DDVP-containing diets for 28 days and then subcutaneously inoculated with tumor cells; and the control (CTRL) group, composed of mice fed a basal diet. After 7 and 21 days of tumor inoculation, the mice were euthanized; and after necroscopic examination, the neoplastic mass, organs, and intraperitoneal fluid were collected. Adherent peritoneal cells were cultivated to determine the production of H₂O₂ and TNF. Altogether, our results indicate that even at low doses, the intake of DDVP caused weight loss and increased tumor mass, which were associated with H₂O₂ production and high levels of TNF, a pro-inflammatory cytokine. These data are important as the exposure to pesticides, even at low doses, could potentially hinder the immune response against tumors and, consequently, create favorable conditions for their development.

Immunotoxicity, genotoxicity and epigenetic toxicity of nanomaterials: New strategies for toxicity testing?

The unique properties of nanomaterials (NMs) are beneficial in numerous industrial and medical applications. However, they could also induce unintended effects. Thus, a proper strategy for toxicity testing is essential in human hazard and risk assessment. Toxicity can be tested in vivo and in vitro; in compliance with the 3Rs, alternative strategies for in vitro testing should be further developed for NMs. Robust, standardized methods are of great importance in nanotoxicology, with comprehensive material characterization and uptake as an integral part of the testing strategy. Oxidative stress has been shown to be an underlying mechanism of possible toxicity of NMs, causing both immunotoxicity and genotoxicity. For testing NMs in vitro, a battery of tests should be performed on cells of human origin, either cell lines or primary cells, in conditions as close as possible to an in vivo situation. Novel toxicity pathways, particularly epigenetic modification, should be assessed along with conventional toxicity testing methods. However, to initiate epigenetic toxicity screens for NM exposure, there is a need to better understand their adverse effects on the epigenome, to identify robust and reproducible causal links between exposure, epigenetic changes and adverse phenotypic endpoints, and to develop improved assays to monitor epigenetic toxicity.

Macrophage activity and histopathology of the lymphohematopoietic organs in male Wistar rats orally exposed to single or mixed pesticides

The noxious effects of low or effective dose exposure to single or mixed pesticides on macrophage activity and the lymphohematopoietic organs were investigated. Male Wistar rats were orally exposed to dichlorvos, dicofol, endosulfan, dieldrin and permethrin, either as single or combined mixtures during a 28-day study containing eight groups: one group received a semipurified diet (non-treated); two groups received a semipurified diet containing low dose mixture (dieldrin 0.025 mg/kg, endosulfan, 0.6 mg/kg, dicofol 0.22 mg/kg, dichlorvos 0.23 mg/kg, permethrin 5 mg/kg) or an effective dose mixture (dichlorvos 2.3 mg/kg, dicofol 2.5 mg/kg, endosulfan 2.9 mg/kg, dieldrin 0.05 mg/kg and permethrin 25.0 mg/kg), respectively; the other five groups received a semipurified diet containing each single pesticide in effective doses. At sacrifice, the thymus, spleen, mesenteric lymph nodes, Payer's patches and bone marrow were removed for histological analysis. Peritoneal macrophages were obtained to determine the phagocytosis and spreading indexes and tumoral necrosis factor alpha (TNF-α), nitric oxide (NO) and H₂O₂ production. Exposure to pesticide mixtures did not alter the percentage of macrophage phagocytosis and spreading, TNF-α production or the NO and H₂O₂ release when compared to the non-treated group. Neither was there any apparent evidence that a pesticide mixture at low or effective doses altered the histological structure of the lymphohematopoietic organs. The findings indicate that short-term treatment with pesticide mixtures did not induce an apparent immunotoxic effect in male Wistar rats.

Effect of acetaminophen (paracetamol) on human osteosarcoma cell line MG63

AIM

To examine the effects of acetaminophen (paracetamol), a nonsteroidal anti-inflammatory drug (NSAID), on different cellular and functional parameters of the human osteosarcoma cell line MG63.

METHODS

Flow cytometry was used to study proliferation, antigenic profile, and phagocytic activity, and radioimmunoassay was used to determine osteocalcin synthesis as a cell differentiation marker.

RESULTS

Short-term treatment with therapeutic doses of paracetamol(5 or 25 μmol/L) reduced cell proliferation, osteocalcin synthesis, and phagocyte activity, and increased the expression of antigens involved in antigen presentation to T lymphocytes (CD80, CD86, HLA-DR).

CONCLUSION

These findings suggest that paracetamol activates the osteoblast, inducing its immunogenic action to the detriment of its bone formation capacity.