Fluoride-induced headkidney macrophage cell apoptosis involves activation of the CaMKIIg-ERK 1/2-caspase-8 axis: the role of superoxide in initiating the apoptotic cascade

Duvira Antarctic polysaccharide inhibited H1N1 influenza virus-induced apoptosis through ROS mediated ERK and STAT-3 signaling pathway

BACKGROUND

The H1N1 influenza virus causes acute respiratory tract infection, and its clinical symptoms are very similar to those of ordinary influenza. The disease develops rapidly. If the flu is not treated, complications such as pneumonia, respiratory failure, and multiple organ damage can occur, resulting in a high fatality rate. Influenza virus mutates rapidly. At present, there is no specific drug for H1N1, so it is an urgent need for clinical care to find new drugs to treat H1N1.

MATERIALS AND METHODS

The polysaccharide derived from Durvillaea Antarctica green algae has a certain antiviral effect. In this study, the results of CCK-8, apoptosis cycle detection, JC-1 and Western blotting proved that Duvira Antarctic polysaccharide (DAPP) has the ability to inhibit H1N1 infection.

RESULTS

CCK-8 test showed that the DAPP with concentration at 32 μg/mL had no toxicity to MDCK cells. In addition, DAPP reduced cell apoptosis by inhibiting the ERK signaling pathway. Meanwhile, DAPP could increase the expression of STAT3 and significantly inhibited proinflammatory cytokines.

CONCLUSIONS

In summary, these results suggested that DAPP may be potential with the ability to resist the H1N1 influenza virus.

Effects of Fluorine on Neutrophil Extracellular Trap Formation through Regulating AMPK/p38 Signaling Pathway

Fluorine is an important trace element that is widely dispersed, and studies showed that fluorine could cause severe toxicity to fish. The aim of this study was to investigate the effects of fluorine on neutrophil extracellular trap (NET) formation in common carp and clarify the possible mechanism. The neutrophils were isolated and exposed to 0.25, 0.5, or 1 mM sodium fluoride (NaF). The results showed that NaF could induce the formation of NETs which exhibited a DNA-based network structure modified with histones and myeloperoxidase (MPO). Furthermore, NaF led to the production of reactive oxygen species (ROS) in neutrophils. Western blot results showed that NaF significantly increased the phosphorylation of AMPK and p38. In addition, our results showed that NaF-induced NET formation could be inhibited by an AMPK or p38 inhibitor. In conclusion, our results showed that NaF induced NET formation in neutrophils through regulation of the AMPK/p38 signaling pathway.

Improved in vivo stability of silicon-containing polyurethane by fluorocarbon side chain modulation of the surface structure

As a class of widely used biomedical materials, polyurethanes suffer from their insufficient stability in vivo. Although the commercialized silicone-polyetherurethanes (SiPEUs) have demonstrated excellent biostability compared with polyetherurethanes (PEUs) for long-term implantation, the usage of polydimethylsiloxane (PDMS) inevitably decreased the mechanical properties and unexpected breaches were observed. In this study, we introduced a fluorinated diol (FDO) into SiPEU to modulate the molecular interactions and micro-separated morphology. The fluorinated silicon-containing polyurethane (FSiPEU) was achieved with desirable silicone- and fluorine-enriched surfaces and mechanical properties at a low silicon content. As evidenced by in vitro culture of macrophages and in vivo hematoxylin-eosin (H&E) staining, FSiPEU demonstrated a minimized inflammatory response. After implantation in mice for 6 months, the material was devoid of significant surface degradation and had the least chain cleavage of soft segments. The results indicate that FSiPEU could be promising candidates for long-term implantation considering the combination of biostability, biocompatibility and mechanical performances.

Cadmium induced oxystress alters Nrf2-Keap1 signaling and triggers apoptosis in piscine head kidney macrophages

Cadmium (Cd) with no known functional role in any life-form has myriad of harmful effects. The present study was designed to elucidate the mechanism of Cd-induced oxystress generation and its impact on antioxidant and apoptosis signaling pathways in head kidney macrophage (HKM) of Channa punctatus Bloch. Fish were sampled and acclimatized with one group treated with cadmium chloride (CdCl₂) (1.96 mg/L) and another as untreated control group, both kept under observation for 7 days. Exposure to Cd caused ultrastructural changes along with reduced head kidney somatic index (HKSI). Significantly increased levels of reactive oxygen species (ROS), respiratory burst activity, lipid peroxidation, DNA fragmentation and superoxide dismutase were found in the HKM from the treated group as compared to control. In contrast, antioxidant enzymes like catalase and reduced glutathione activity decreased in the Cd exposed group. The suppressed antioxidant activity was further confirmed and corroborated from the altered expression of Kelch-like ECH-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor 2 (Nrf2) genes, the major player of antioxidant pathway. Cd induced alteration in Nrf2-Keap1 signaling pathway was also validated by the diminished levels of Nrf2 dependent expression of protein like heme oxygenase-1 (HO-1). The flow cytometry analysis supported the event of apoptosis in Cd exposed group as compared to control, which was further confirmed by the upregulated expression of caspase-3, caspase-8, caspase-9, TNF-α and p53 genes from the real-time gene expression study. In addition, altered protein level of cytochrome C validates the incidence of apoptosis. Altogether, our results demonstrate that exposure to Cd caused oxidative stress in HKM of Channa punctatus Bloch. by compromising the antioxidant enzyme activities via the down regulation of expression of genes related to antioxidant signaling pathway besides encouraging apoptosis via both mitochondrial and death receptor pathway.

Chronic fluoride exposure exacerbates headkidney pathology and causes immune commotion in Clarias gariepinus

The current study was aimed to understand the effects of chronic fluoride exposure on fish immune system. African sharp tooth catfish (Clarias gariepinus) were exposed to 73.45mg/L of fluoride corresponding to 1/10 96h LC₅₀ for 30 d and the effects on general fish health and several immune parameters were studied. Chronic fluoride exposure led to significant alteration in serum biochemical parameters including alkaline phosphatase, alanine transaminase, aspartate transaminase, triglycerides, cholesterol and blood urea nitrogen levels revealing the detrimental effect of fluoride on general fish health. Upregulation in cytochrome P450 1A expression, both at mRNA and protein level suggested that fluoride activates the detoxification machinery in headkidney (HK) of C. gariepinus. Histopathological analysis of HK from exposed fish further revealed fluoride-induced hypertrophy, increase in melano-macrophage centers (MMCs) and the development of cell-depleted regions. Fluoride reduced headkidney somatic index (HKSI) and the phagocytic potential of headkidney macrophages (HKM). It induced caspase-3-dependent headkidney leukocyte (HKL) apoptosis, elevated superoxide generation and production of pro-inflammatory cytokine TNF-α besides suppressed T-cell proliferation in the exposed fish. We surmise the elevation in superoxide levels coupled with increased TNF-α production to be plausible causes of fluoride-induced HKL apoptosis. It is concluded that chronic fluoride exposure induces structure-function alterations in HK, the primary lymphoid organ in fish leading to impairment in immune responses.

Effects of sodium fluoride on blood cellular and humoral immunity in mice

Exposure to high fluorine can cause toxicity in human and animals. Currently, there are no systematic studies on effects of high fluorine on blood cellular immunity and humoral immunity in mice. We evaluated the alterations of blood cellular immunity and humoral immunity in mice by using flow cytometry and ELISA. In the cellular immunity, we found that sodium fluoride (NaF) in excess of 12 mg/Kg resulted in a significant decrease in the percentages of CD3+, CD3+CD4+, CD3+CD8+ T lymphocytes in the peripheral blood. Meanwhile, serum T helper type 1 (Th1) cytokines including interleukin (IL)-2, interferon (IFN)-γ, tumor necrosis factor (TNF), and Th2 cytokines including IL-4, IL-6, IL-10, and Th17 cytokine (IL-17A) contents were decreased. In the humoral immunity, NaF reduced the peripheral blood percentages of CD19+ B lymphocytes and serum immunoglobulin A (IgA), immunoglobulin G (IgG) and immunoglobulin M (IgM). The above results show that NaF can reduce blood cellular and humoral immune function in mice, providing an excellent animal model for clinical studies on immunotoxicity-related fluorosis.

Chronic endosulfan exposure impairs immune response rendering Clarias gariepinus susceptible to microbial infection

Endosulfan, a persistent organochlorine insecticide affects several off-target organisms including fish though the underlying mechanisms remain obscure. In the present study, we monitored the effect of chronic endosulfan exposure on headkidney (HK), an important immune organ in fish and on fish immune system thereof. Clarias gariepinus were exposed to a non-lethal concentration of endosulfan 2.884ppb (1/10th LC₅₀) for 30 d which resulted in suppressed phagocytosis and bactericidal potential of headkidney macrophages (HKM). The same non-lethal concentration of endosulfan also interfered with T-cell proliferation and serum antibody titer in fish. Endosulfan-exposed fish were challenged with non-lethal dose of fish pathogenic bacteria Aeromonas hydrophila and the 'exposure-challenge' study revealed endosulfan-exposed C. gariepinus severely immunocompromised and prone to bacterial infections. Depuration for 30 d suggested that except for phagocytosis and serum agglutination titer other endosulfan-induced immune aberrations could not be restored significantly. Nonetheless, compared to exposed-challenged fish the depurated fish showed significant improvement in viability on challenge with A. hydrophila. Collectively, these findings suggest chronic endosulfan exposure has prolonged effect on fish making them prone to microbial infections.