PFOS mediates immunomodulation in an avian cell line that can be mitigated via a virus infection

Abstract

Background Per- and polyfluoroalkyl substances (PFASs) are environmentally persistent and bioaccumulative chemicals. Immunomodulation is among the most concerning of toxic effects linked with PFAS exposure in mammalian models. However, no studies had yet shown this to be true in birds. Thus, we designed and conducted the first study to determine if PFASs could cause immunomodulation in birds. Secondly, we wanted to determine the effects on an avian host when exposed not only to immunomodulating chemicals, but also to a viral challenge. The aim, to determine if PFAS mediated immunmodulation functionally affects a pathogen challenge for a host. As innate immune system signalling pathways initiate crucial responses against a pathogen challenge, and are lesser studied than their adaptive counterparts, we focused on these pathways. To provide the first information on this, an in vitro experiment was designed and performed using chicken embryo fibroblasts exposed to perfluorooctane sulfonate (PFOS) (22 ppm) and immune markers characterised before and after being infected with gallid herpesvirus-2 (GaHV-2). Results The expression of two pro-inflammatory cytokines, namely interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-α), the nuclear factor ‘kappa-light-chain-enhancer’ of activated B-cells (NF-κB), and the anti-inflammatory cytokine interleukin 4 (IL-4) were investigated in various scenarios. These results showed that exposure to PFOS decreased immune gene expression in chicken fibroblasts from 36 h post-exposure. Next, it was shown that this decrease could be mitigated by infection with gallid herpesvirus-2, which increased gene expression back to the baseline/control levels. Conclusions Not only is this the first study to provide the expected evidence that PFOS has immunomodulatory potential in birds, it also provides unexpected data that virus infections can mitigate this negative effect. Thereby, further research, including in vivo and in situ studies, on the impact of PFOS on host-virus interactions is now warranted, as it has been overlooked and might contribute to our understanding of recent disease outbreaks in wildlife. The mechanisms by which gallid herpesvirus mitigates immunomodulation were beyond the scope of this study, but are now of interest for future study. Electronic supplementary material The online version of this article (10.1186/s12917-019-1953-2) contains supplementary material, which is available to authorized users.

Environmental pollutants modulate RNA and DNA virus-activated miRNA-155 expression and innate immune system responses: Insights into new immunomodulative mechanisms*

“…These results indicated that GaHV-2 was the main agent involved in induction of NF-jB-dependent signaling after 8 h, since Ar1260 polluted/uninfected cells did not significantly up-regulate expression of any of the investigated genes. Similar observations were made in a study of perfluorooctane sulfonate (PFOS)/GaHV-2-infected CEF, wherein the combined treatment resulted in a similar expression of NF-jB1, TNFa, IL-8, and IL-4 compared to unpolluted/ GaHV-2-infected CEF (Castaño-Ortiz et al 2019).…”

“…Cell culture, exposure to Ar1260, virus intermediate inoculation, and GaHV-2 infection All experiments were conducted with CEFs (ATCC CRL12203, Gallus gallus embryo, spontaneously-transformed) of the same passage to ensure comparable results. The CEF were cultivated in Dulbecco's modified Eagle's medium (DMEM, Sigma, Oslo, Norway), 5% fetal calf serum, 10 mg gentamycin/ml, 100 units penicillin/ml, and 100 U streptomycin/ml (complete growth medium) (Castaño-Ortiz et al 2019). The cells were seeded at a density of 5.2 Â 104 cells/ml in 96-well plates and incubated at 39 C with 5% CO 2 for 48 h. Thereafter, the treatment groups were cells exposed to Ar1260 (22.23 ppm dissolved in corn oil; this concentration was chosen based on preliminary experiments done to attain a sublethal concentration in the CEF) and control cells that received vehicle only.…”

Primary Cell Lines From Feathers and Blood of Free-Living Tawny Owls (Strix aluco): A New In Vitro Tool for Non-Lethal Toxicological Studies

“…The assay discovers the compound’s ability to block or cause biological activity without having toxic effects on cells ( Creative Bioarray, 2022 ), which makes it possible to investigate the pollutant levels in the cells before further in vitro experiments. TOFF cells can be used for infection/exposure studies with pollutants and pathogens of choice ( Waugh et al, 2018 ; Castaño-Ortiz et al, 2019 ; Badry et al, 2020a )). Previous studies performed on domestic chicken secondary cell lines have already demonstrated the beneficial use of cell lines in exposure studies where cell cultures have been exposed to environmentally relevant concentrations of pollutants such as PFOS and PCBs, and infected with DNA- and RNA viruses to investigate the downstream immunological responses (e.g.…”

“…Previous studies performed on domestic chicken secondary cell lines have already demonstrated the beneficial use of cell lines in exposure studies where cell cultures have been exposed to environmentally relevant concentrations of pollutants such as PFOS and PCBs, and infected with DNA- and RNA viruses to investigate the downstream immunological responses (e.g. the expression pattern for mir-155, pro-inflammatory TNFα and IL-8, transcription factor NF-κB1, and anti-inflammatory IL-4) on a cellular level ( Waugh et al, 2018 ; Castaño-Ortiz et al, 2019 ; Badry et al, 2020a ). These studies all showed concerning modulations in the immunological responses after exposure to different pollutants (PFOS and PCB).…”

“…There are also several studies that describes how secondary cell lines have been used to study immunological responses to viral infection and pollutant exposure for e.g. the effects of PFOS and PCBs on chicken fibroblasts ( Waugh et al, 2018 ; Castaño-Ortiz et al, 2019 ; Badry et al, 2020a ), and p,p-DDE exposure on immortalised humpback whale fibroblast cell lines isolated from the dermal connective tissue of skin biopsies ( Burkard et al, 2015 ).…”