Methods in food defence: a simple and robust screening for 16 rodenticides by LC-DAD/FLD following QuEChERS-based extraction.

Fortunately, the intentional contamination of food or water supplies out of criminal or terroristic motivation is a rather rare event. However, in the face of asymmetric warfare and as the consequences of such an event would be severe, food defence as a necessary supplement to food safety is gaining increased attention. While some progress has been made in developing non-target detection devices, the contamination of food or water supplies using readily available rodenticides may still be revealed only by complex analytical techniques. The presented study therefore aimed to develop a quick and easy screening method for the detection of sixteen globally common rodenticides in foodstuffs. Robust operation with limited personnel and analytical resources were one benchmark to be met by the method, which uses a slightly modified QuEChERS (quick, easy, cheap, effective, rugged, safe) protocol for dispersive solid-phase extraction and subsequent ion-pair chromatography with diode-array and fluorescence detection. Quantification limits were as low as 5 µg/kg with satisfying bias (recovery) and repeatability rates of 77 to 117% and 1.8 to 17.1%, respectively. The developed method provides reliable and robust detection of these deadly poisons at toxic concentrations, which was demonstrated impressively in an improvised assault scenario.

Validation of automated pipetting systems for cell culture seeding, exposure and bio-analytical assays in sulfur mustard toxicology.

In vitro cell culture experiments are highly important techniques to accelerate drug discovery, conduct safety testing and reduce the need for animal studies. Therefore, automatization may help to enhance the technical precision, reduce external (including operator's) influence on the data and thus improve reliability. Prior to application in scientific studies, validation of automated systems is absolutely necessary. In this study we present the validation of two combined automated pipetting systems to conduct toxicity studies in HaCaT cells consisting of cell seeding, noxious agent exposure and several assays to assess cell survival, apoptosis and interleukin production. After initial validation of pipetting accuracy, we compared homogeneity after automated seeding to plates seeded by expert laboratory technicians. Moreover, automated dispensing of a potentially unstable noxious agent was analyzed in terms of speed and consistency. We found a 2 % technical imprecision for the cell survival assay and 4.5-6 % for the other assays, bioluminescent and ELISA techniques. Thus, we could demonstrate the excellent technical precision of our assays. In a final step, we found that intraday variations, though acceptable, were much larger than technical variations and had to assume an intraday biological variability between different wells of the same experimental group.

Necrosulfonamide - Unexpected effect in the course of a sulfur mustard intoxication.

Although its first military use in Ypres was 100 years ago, no causal therapy for sulfur mustard (SM) intoxications exists so far. To improve the therapeutic options for the treatment of SM intoxications, we developed a co-culture of keratinocytes (HaCaT cells) and immunocompetent cells (THP-1 cells) to identify potential substances for further research. Here, we report on the influence of necrosulfonamide (NSA) on the course of a SM intoxication in vitro. The cells were challenged with 100, 200 and 300 µM SM and after 1 h treated with NSA (1, 5, 10 µM). NSA was chosen for its known ability to inhibit necroptosis, a specialized pathway of programmed necrosis. However, in our settings NSA showed only mild effects on necrotic cell death after SM intoxication, whereas it had an immense ability to prevent apoptosis. Furthermore, NSA was able to reduce the production of interleukin-6 and interleukin-8 at certain concentrations. Our data highlight NSA as a candidate compound to address cell death and inflammation in SM exposure.

Effects of anti-inflammatory compounds on sulfur mustard injured cells: Recommendations and caveats suggested by in vitro cell culture models.

Sulfur mustard (SM) is a vesicant agent who had its first military use 100 years ago, in Ypres. Since then it has been used in several conflicts like the Iran-Iraq war in the 1980s. The use of SM in Syria 2015 indicated the still existing threat. Despite decades of research no causal antidote against SM intoxication is available, so far. A SM intoxication is accompanied by necrosis, apoptosis and inflammation. To counteract the SM-induced inflammation, glucocorticoids and non-steroidal anti-inflammatory compounds (NSAIDs) are recommended. Aim of this study was to evaluate the efficacy of the anti-inflammatory compounds dexamethasone, ibuprofen and diclofenac in vitro. For that purpose, two different cell culture models were used. Firstly, a monoculture of keratinocytes (HaCaT) and secondly, an established co-culture of keratinocytes (HaCaT) and immunocompetent cells (THP-1) to identify the role of immune cells in the process and to mimic the dermal physiology more closely. Both models were challenged with different SM concentrations (100, 200 and 300µM) and treated with different anti-inflammatory compounds one hour after the SM exposure. Analytical analysis of necrosis (ToxiLight), apoptosis (CDDE) and inflammation (IL-6 and -8 ELISAs) followed 24h thereafter. Dexamethasone provided small but consistent protective effects in the monoculture. For the reduction of apoptosis, 3µM dexamethasone was sufficient. The most effective reduction regarding interleukin (IL) production was found with 6µM dexamethasone. Protective effects were less pronounced in co-culture, which implies, that the protective effects of dexamethasone are rather generic and not due to a modulation of the immune cells. Against our expectations, ibuprofen strongly amplified apoptosis and necrosis in SM exposed cells in the monoculture as well as the co-culture. Therefore, use of ibuprofen for treatment of SM intoxication should at least be considered most critically, if not even regarded as harmful. Diclofenac significantly reduced necrosis, apoptosis and inflammation in the co-culture in a dose-dependent manner. The greatest benefit regarding cell survival and reduction of the inflammation-marker IL-6 after a SM treatment was observed after diclofenac treatment. The protective effects of diclofenac were less pronounced in the monoculture which suggests, that diclofenac can modify the response of immune cells to SM. In conclusion, the results of our experiments, showing a benefit for diclofenac after SM exposure are in line with in vivo data of other researchers. Though, our in vitro results suggest the preferred use of diclofenac over ibuprofen. The benefit of dexamethasone is still equivocal, but low concentrations seem to have some positive effects.

Anti-apoptotic and moderate anti-inflammatory effects of berberine in sulfur mustard exposed keratinocytes.

Skin affections after sulfur mustard (SM) exposure include erythema, blister formation and severe inflammation. An antidote or specific therapy does not exist. Anti-inflammatory compounds as well as substances counteracting SM-induced cell death are under investigation. In this study, we investigated the benzylisoquinoline alkaloide berberine (BER), a metabolite in plants like berberis vulgaris, which is used as herbal pharmaceutical in Asian countries, against SM toxicity using a well-established in vitro approach. Keratinocyte (HaCaT) mono-cultures (MoC) or HaCaT/THP-1 co-cultures (CoC) were challenged with 100, 200 or 300mM SM for 1h. Post-exposure, both MoC and CoC were treated with 10, 30 or 50µM BER for 24h. At that time, supernatants were collected and analyzed both for interleukine (IL) 6 and 8 levels and for content of adenylate-kinase (AK) as surrogate marker for cell necrosis. Cells were lysed and nucleosome formation as marker for late apoptosis was assessed. In parallel, AK in cells was determined for normalization purposes. BER treatment did not influence necrosis, but significantly decreased apoptosis. Anti-inflammatory effects were moderate, but also significant, primarily in CoC. Overall, BER has protective effects against SM toxicity in vitro. Whether this holds true should be evaluated in future in vivo studies.

Protective effects of the thiol compounds GSH and NAC against sulfur mustard toxicity in a human keratinocyte cell line.

Sulfur mustard (SM) is a chemical warfare agent causing blistering, inflammation and ulceration of the skin. Thiol compounds such as glutathione (GSH) and N-acetylcysteine (NAC) have been suggested as potential antidotes. We investigated SM toxicity in a human keratinocyte cell line (HaCaT) and used GSH and NAC to counteract its cytotoxic effects. Cells were treated with 1, 5 or 10mM GSH or NAC and exposed to 30, 100 or 300µM SM. Different treatment regimens were applied to model extra- and intra-cellular GSH/NAC effects on SM toxicity. Necrosis, apoptosis and interleukin-6 and -8 levels were determined 24h post-exposure. Necrosis and apoptosis increased with SM dose. Interleukin-6 and -8 production peaked at 100µM and decreased at 300µM probably due to reduced ability for interleukin biosynthesis. Intracellular GSH/NAC diminished necrosis induced by 100µM SM. Extracellular GSH/NAC protected against necrosis and apoptosis induced by 100 and 300µM SM. Interleukin-6 and -8 production, induced by 100µM SM was reduced by GSH/NAC. However, low-dose GSH/NAC treatment of cells exposed to 300µM SM led to increased interleukin production. Thus, moderately poisoned cells are mostly responsible for SM-induced secretion of pro-inflammatory cytokines. GSH and NAC treatment can reduce SM-induced toxic effects. Protective effects were more pronounced by extracellular GSH or NAC administration. Rescue of severely poisoned cells may result in a strong secretion of pro- inflammatory cytokines. In summary, thiol compounds such as GSH or NAC constitute a promising approach to improve the therapy for SM injury. Additional intervention to prevent adverse effects of interleukin production might be beneficial.

Development of a co-culture of keratinocytes and immune cells for in vitro investigation of cutaneous sulfur mustard toxicity.

Sulfur mustard (SM) is a chemical warfare agent causing skin blistering, ulceration and delayed wound healing. Inflammation and extrinsic apoptosis are known to have an important role in SM-induced cytotoxicity. As immune cells are involved in those processes, they may significantly modulate SM toxicity, but the extent of those effects is unknown. We adapted a co-culture model of immortalized keratinocytes (HaCaT) and immune cells (THP-1) and exposed this model to SM. Changes in necrosis, apoptosis and inflammation, depending on SM challenge, absence or presence and number of THP-1 cells were investigated. THP-1 were co-cultured for 24h prior to SM exposure in order to model SM effects on immune cells continuously present in the skin. Our results indicate that the presence of THP-1 strongly increased necrosis, apoptosis and inflammation. This effect was already significant when the ratio of THP-1 and HaCaT cells was similar to the ratio of Langerhans immune cells and keratinocytes in vivo. Any further increases in the number of THP-1 had only slight additional effects on SM-induced cytotoxicity. In order to assess the effects of immune cells migrating into skin areas damaged by SM, we added non-exposed THP-1 to SM-exposed HaCaT. Those THP-1 had only slight effects on SM-induced cytotoxicity. Notably, in HaCaT exposed to 300µM SM, necrosis and inflammation were slightly reduced by adding intact THP-1. This effect was dependent on the number of immune cells, steadily increasing with the number of unexposed THP-1 added. In summary, we have demonstrated that (a) the presented co-culture is a robust model to assess SM toxicity and can be used to test the efficacy of potential antidotes in vitro; (b) immune cells, damaged by SM strongly amplified cytotoxicity, (c) in contrast, unexposed THP-1 (simulating migration of immune cells into affected areas after exposure in vivo) had no pronounced adverse, but exhibited some protective effects. Thus, protecting immune cells from SM toxicity may help to reduce overall injury.