Acrylamide induced the activation of NLRP3 inflammasome via ROS-MAPKs pathways in Kupffer cells

Exploring the health benefits of food bioactive compounds from a perspective of NLRP3 inflammasome activation: an insight review

The food industry has been focusing on food bioactive compounds with multiple physiological and immunological properties that benefit human health. These bioactive compounds, including polyphenols, flavonoids, and terpenoids, have great potential to limit inflammatory responses especially NLRP3 inflammasome activation, which is a key innate immune platform for inflammation. Current studies have revealed numerous food bioactive compounds with promising activities for unraveling immune metabolic disorders and excessive inflammatory responses by directly and indirectly regulating the NLRP3 inflammasome activation. This review explores the food hazards, including microbial and abiotic factors, that may trigger NLRP3-mediated illnesses and inflammation. It also highlights bioactive compounds in food that can suppress NLRP3 inflammasome activation through various mechanisms, linking its activation and inhibition to different pathways. Especially, this review provided further insight into NLRP3-related targets where food bioactive compounds can interact to block the NLRP3 inflammasome activation process, as well as mechanisms on how these compounds facilitate inactivation processes.

Mechanism of apoptosis induced by the combined action of acrylamide and Elaidic acid through endoplasmic reticulum stress injury

Thermal processing of food is likely to form acrylamide (AA) and elaidic acid (EA), which are both mainly metabolized by the liver. The two substances are associated with the pathogenesis of liver disease. In the current study, we investigated the toxic effects of the combined action of AA and EA on HSC-T6 cells, and the mechanism of apoptosis exacerbated by the co-exposure. The results showed a synergistic effect of AA and EA, which exacerbated the damage and oxidative stress (OS) in HSC-T6. Meanwhile, the expression of endoplasmic reticulum stress (ERS) proteins, such as GRP78 and CHOP, was increased, the ERS pathway was activated, and Ca2+ in cells was increased, which exacerbated mitochondrial damage, and opened IP3R-Grp75-VDAC1 channel. Both ERS and mitochondrial damage caused the process of cell apoptosis. Inhibition of ERS by 4-phenylbutyric acid (4-PBA) significantly reversed the synergistic effects on mitochondrial damage via ERS, suggesting that AA and EA exacerbated mitochondrial damage through ERS-mediated Ca2+ overload. AA and EA synergistically damaged the function of mitochondria through exacerbating ERS and led to cell apoptosis.

Acrylamide in food: Occurrence, metabolism, molecular toxicity mechanism and detoxification by phytochemicals

Acrylamide (ACR) is a common pollutant formed during food thermal processing such as frying, baking and roasting. ACR and its metabolites can cause various negative effects on organisms. To date, there have been some reviews summarizing the formation, absorption, detection and prevention of ACR, but there is no systematic summary on the mechanism of ACR-induced toxicity. In the past five years, the molecular mechanism for ACR-induced toxicity has been further explored and the detoxification of ACR by phytochemicals has been partly achieved. This review summarizes the ACR level in foods and its metabolic pathways, as well as highlights the mechanisms underlying ACR-induced toxicity and ACR detoxification by phytochemicals. It appears that oxidative stress, inflammation, apoptosis, autophagy, biochemical metabolism and gut microbiota disturbance are involved in various ACR-induced toxicities. In addition, the effects and possible action mechanisms of phytochemicals, including polyphenols, quinones, alkaloids, terpenoids, as well as vitamins and their analogs on ACR-induced toxicities are also discussed. This review provides potential therapeutic targets and strategies for addressing various ACR-induced toxicities in the future.

Acrylamide induces ferroptosis in HSC-T6 cells by causing antioxidant imbalance of the XCT-GSH-GPX4 signaling and mitochondrial dysfunction

Acrylamide (AA) is a heat-induced food contaminant, mainly metabolized by the liver. Increasing evidences have proved that ferroptosis is linked to the pathogenesis of liver disease. In the current study, the underlying mechanism of AA-induced rat hepatic stellate (HSC-T6) cells ferroptosis was investigated by detecting changes in iron levels, expressions of ferroptosis-related proteins and indicators of mitochondrial dysfunction. The results showed that AA treatment led to iron levels increased and expressions of long-chain acyl-CoA synthase 4 (ACSL4), cyclooxygenase 2 (COX2) and ferritin heavy chain 1 (FTH1) proteins in HSC-T6 cells were all altered. Treatment with the ferroptosis inhibitor ferrostatin-1 (Fer-1) markedly reversed the impact of AA, suggesting that AA induced ferroptosis in HSC-T6 cells. Mechanistically, AA induced the onset of ferroptosis by affecting XCT-GSH-GPX4 antioxidant signaling. Moreover, AA created a peroxidative environment for ferroptosis by inducing oxidative stress in HSC-T6 cells through mitochondrial dysfunction, as evidenced by increased mitochondrial ROS (mtROS) release, mitochondrial membrane potential (MMP) depolarization, and decreased mitochondrial ATP. Our results indicated that AA resulted in mitochondrial dysfunction and ferroptosis, and dysregulation of XCT-GSH-GPX4 antioxidant signaling was a key factor in AA-induced ferroptosis.

Acrylamide inhibits long-term potentiation and learning involving microglia and pro-inflammatory signaling

Acrylamide is a chemical used in various industries and a product following high-temperature cooking of vegetables containing asparagine. Environmental or dietary exposure to acrylamide could impair cognitive function because of its neurotoxicity. Using rat hippocampal slices, we tested whether acrylamide alters induction of long-term potentiation (LTP), a cellular model of learning and memory. We hypothesized that acrylamide impairs cognitive function via activation of pro-inflammatory cytokines because robust upregulation of NLRP3 inflammasome has been reported. Although acrylamide up to 3 mM did not alter basal synaptic transmission, incubation with 10 μM or acute administration of 100 μM acrylamide inhibited induction of LTP. Inhibitors of toll-like receptor 4 (TLR4), and minocycline, an inhibitor of microglial activation, overcame the effects of acrylamide on LTP induction. Furthermore, we observed that acrylamide failed to inhibit LTP after administration of MCC950, an inhibitor of NLRP3, or in the presence of Interleukin-1 receptor antagonist (IL-1Ra). We also found that in vivo acrylamide injection transiently impaired body weight gain and impaired one-trial inhibitory avoidance learning. This learning deficit was overcome by MCC950. These results indicate that cognitive impairment by acrylamide is mediated by mechanisms involving microglia and release of cytokines via NLRP3 activation.

Transcriptomic analysis of the seminal vesicle response to the reproductive toxicant acrylamide

BACKGROUND

The seminal vesicles synthesise bioactive factors that support gamete function, modulate the female reproductive tract to promote implantation, and influence developmental programming of offspring phenotype. Despite the significance of the seminal vesicles in reproduction, their biology remains poorly defined. Here, to advance understanding of seminal vesicle biology, we analyse the mouse seminal vesicle transcriptome under normal physiological conditions and in response to acute exposure to the reproductive toxicant acrylamide. Mice were administered acrylamide (25 mg/kg bw/day) or vehicle control daily for five consecutive days prior to collecting seminal vesicle tissue 72 h following the final injection.

RESULTS

A total of 15,304 genes were identified in the seminal vesicles with those encoding secreted proteins amongst the most abundant. In addition to reproductive hormone pathways, functional annotation of the seminal vesicle transcriptome identified cell proliferation, protein synthesis, and cellular death and survival pathways as prominent biological processes. Administration of acrylamide elicited 70 differentially regulated (fold-change ≥1.5 or ≤ 0.67) genes, several of which were orthogonally validated using quantitative PCR. Pathways that initiate gene and protein synthesis to promote cellular survival were prominent amongst the dysregulated pathways. Inflammation was also a key transcriptomic response to acrylamide, with the cytokine, Colony stimulating factor 2 (Csf2) identified as a top-ranked upstream driver and inflammatory mediator associated with recovery of homeostasis. Early growth response (Egr1), C-C motif chemokine ligand 8 (Ccl8), and Collagen, type V, alpha 1 (Col5a1) were also identified amongst the dysregulated genes. Additionally, acrylamide treatment led to subtle changes in the expression of genes that encode proteins secreted by the seminal vesicle, including the complement regulator, Complement factor b (Cfb).

CONCLUSIONS

These data add to emerging evidence demonstrating that the seminal vesicles, like other male reproductive tract tissues, are sensitive to environmental insults, and respond in a manner with potential to exert impact on fetal development and later offspring health.

Elaidic acid induced NLRP3 inflammasome activation via ERS-MAPK signaling pathways in Kupffer cells

Trans fatty acids (TFA) in food can cause liver inflammation. Activation of NOD-like receptor protein-3 (NLRP3) inflammasome is a key factor in the regulation of inflammation. Accumulating evidence suggests that ERS-induced NLRP3 inflammasome activation underlies the pathological basis of various inflammatory diseases, but the precise mechanism has not been fully elucidated. Therefore, this paper focused on TFA, represented by elaidic acid (EA), to investigate the mechanism of liver inflammation. Levels of mRNA and protein were detected by RT-qPCR and Western blotting, the release of proinflammatory cytokines was measured by ELISA, and intracellular Ca²⁺ levels were determined by flow cytometer using Fluo 4-AM fluorescent probes. Our research indicated that EA induced the endoplasmic reticulum stress (ERS) response in Kupffer cells (KCs), accompanied by the activation of the mitogen-activated protein kinase (MAPK) signaling pathway, which resulted in NLRP3 inflammasome formation, and eventually increased the release of inflammatory factors. NLRP3 inflammasome activation was inhibited when KCs were pretreated with ERS inhibitors (4-PBA) and MAPK selective inhibitors. Furthermore, when ERS was blocked, the MAPK pathway was inhibited.

Anti-Inflammatory Activity of Oligomeric Proanthocyanidins Via Inhibition of NF-κB and MAPK in LPS-Stimulated MAC-T Cells

Oligomeric proanthocyanidins (OPCs), classified as condensed tannins, have significant antioxidation, anti-inflammation and anti-cancer effects. This study was performed to investigate the anti-inflammatory effects of OPCs and the mechanism underlying these effects in lipopolysaccharide (LPS)-stimulated bovine mammary epithelial cells (MAC-T). Real-time PCR and ELISA assays indicated that OPC treatment at 1, 3 and 5 μg/ml significantly reduced the mRNA and protein, respectively, of oxidant indicators cyclooxygenase-2 (COX-2) (p < 0.05) and inducible nitric oxide synthase (iNOS) (p < 0.01) as well as inflammation cytokines interleukin (IL)-6 (p < 0.01), IL-1β (p < 0.01) and tumor necrosis factor-α (TNF-α) (p < 0.05) in LPS-induced MAC-T cells. Moreover, OPCs downregulated LPSinduced phosphorylation of p65 and inhibitor of nuclear factor kappa B (NF-κB) (IκB) in the NF-κB signaling pathway (p < 0.01), and they inhibited p65 translocation from the cytoplasm to the nucleus as revealed by immunofluorescence test and western blot. Additionally, OPCs decreased phosphorylation of p38, extracellular signal regulated kinase and c-jun NH₂-terminal kinase in the MAPK signaling pathway (p < 0.01). In conclusion, the anti-inflammatory and antioxidant activities of OPCs involve NF-κB and MAPK signaling pathways, thus inhibiting expression of pro-inflammatory factors and oxidation indicators. These findings provide novel experimental evidence for the further practical application of OPCs in prevention and treatment of bovine mastitis.