Lycopene ameliorates atrazine-induced pyroptosis in spleen by suppressing the Ox-mtDNA/Nlrp3 inflammasome pathway

Nlrp3 is a vital integration point of diverse extracellular stimuli and cellular stress. However, the inappropriate activation of Nlrp3 results in the progression of autoinflammatory and metabolic disorders. Atrazine, which is used widely in the agricultural sector, is toxic to humans. Herein, this study found that atrazine could induce oxidative stress and the expression of Nfkb and IRF1 in spleen, promoting the ox-mtDNA formation. Also, production and release of ox-mtDNA stimulated the Nlrp3 inflammasome. Lastly, atrazine induced pyroptosis in spleen, mediating the activation of Nlrp3 inflammasome. In addition, lycopene, a kind of carotenoid, is natural bioactive component in fruits and vegetables, which is applied toward reducing oxidative stress. It was found that lycopene could ameliorate the pyroptosis induced by atrazine via the inhibition of ox-mtDNA production. The results also provided evidence that lycopene had a potential role in the prevention of Nlrp3 inflammasome activation by depleting the ox-mtDNA.

The Keap1/Nrf2-ARE signaling pathway is involved in atrazine induced dopaminergic neurons degeneration via microglia activation

OBJECTIVE

To investigate the mechanisms of ATR-induced dopaminergic toxicity by microglia activation and the response of the Keap1/ Nrf2- ARE signaling pathway.

METHODS

Wistar rats were treated with 50, 100 and 200 mg/kg ATR and BV-2 microglia cells were treated with 50, 100 μM ATR or 100 ng/mL LPS, respectively. Rats behavioral responses and histopathological changes were monitored. Immunohistochemical and immunofluorescence analysis detected Iba-1 and TH⁺ cells in rats. Keap1/Nrf2-ARE signaling-related proteins and inflammatory factors from BV-2 cells and rats were detected using ELISA, Western blot and Real-time PCR.

RESULTS

After ATR treatment, the grip strength of Wistar rats was significantly decreased, and anxiety were clearly observed. TH⁺ neurons were reduced, however, the number of microglia cells and Iba-1 levels were increased clearly in SN. The release of ROS, TNF-α and IL-Iβ were increased, and levels of SOD and GSH-Px were significantly decreased. Keap1 mRNA expression and protein levels were decreased, while nuclear Nrf2 mRNA expression and protein levels were both increased in vivo and in vitro.

CONCLUSION

ATR could significantly activate microglia and exacerbate neurotoxicity and neuroinflammation, leading to accelerate dopaminergic neuron cell death by inhibiting Keap1/Nrf2-ARE signaling pathway.

Endocrine disruptors also function as nervous disruptors and can be renamed endocrine and nervous disruptors (ENDs)

Endocrine disruption (ED) and endocrine disruptors (EDs) emerged as scientific concepts in 1995, after numerous chemical pollutants were found to be responsible for reproductive dysfunction. The World Health Organization established in the United Nations Environment Programme a list of materials, plasticizers, pesticides, and various pollutants synthesized from petrochemistry that impact not only reproduction, but also hormonal functions, directly or indirectly. Cells communicate via either chemical or electrical signals transmitted within the endocrine or nervous systems. To investigate whether hormone disruptors may also interfere directly or indirectly with the development or functioning of the nervous system through either a neuroendocrine or a more general mechanism, we examined the scientific literature to ascertain the effects of EDs on the nervous system, specifically in the categories of neurotoxicity, cognition, and behaviour. To date, we demonstrated that all of the 177 EDs identified internationally by WHO are known to have an impact on the nervous system. Furthermore, the precise mechanisms underlying this neurodisruption have also been established. It was previously believed that EDs primarily function via the thyroid. However, this study presents substantial evidence that approximately 80 % of EDs operate via other mechanisms. It thus outlines a novel concept: EDs are also neurodisruptors (NDs) and can be collectively termed endocrine and nervous disruptors (ENDs). Most of ENDs are derived from petroleum residues, and their various mechanisms of action are similar to those of "spam" in electronic communications technologies. Therefore, ENDs can be considered as an instance of spam in a biological context.

MicroRNA miR-155-5p knockdown attenuates Angiostrongylus cantonensis-induced eosinophilic meningitis by downregulating MMP9 and TSLP proteins

Angiostrongylus cantonensis infection is a major cause of eosinophilic meningitis (EM). Severe cases or cases that involve infants and children present poor prognoses. MicroRNAs (miRNAs), which are important regulators of gene expression in many biological processes, were recently found to be regulators of the host response to infection by parasites; however, their roles in brain inflammation caused by A. cantonensis are still unclear. The current study confirmed that miR-155-5p peaked at 21 days after A. cantonensis infection, and its expression was positively correlated with the concentration of excretory and secretory products (ESPs). We found that miR-155-5p knockdown lentivirus successfully ameliorated brain injury and downregulated the expression of major basic protein (MBP) in vivo, and the number of eosinophils in CSF (and the percentage of eosinophils in peripheral blood were also decreased in the miR-155-5p knockdown group. Moreover, the expression of several eosinophilic inflammation cytokines such as CCL6/C10, ICAM-1, and MMP9, declined after the miR-155-5p knockdown. SOCS1 protein, which is an important negative regulator of inflammation activation, was identified as a direct miR-155-5p target. We further detected the effect of miR-155-5p knockdown on phosphorylated-STAT3 and phosphorylated-p65 proteins, which were found to be negatively regulated by SOCS1 and play an important role in regulating the inflammatory response. We found that miR-155-5p knockdown decreased the activity of p-STAT3 and p-p65, thereby leading to lower expression of MMP9 and TSLP proteins, which were closely related to the chemotaxis and infiltration of eosinophils. Interestingly, the inhibition of p-STAT3 or p-p65 was found to induce the downregulation of miR-155-5p in an opposite manner. These observations suggest that a positive feedback loop was formed between miR-155-5p, STAT3, and NF-κB in A. cantonensis infection and that miR-155-5p inhibition might provide a novel strategy to attenuate eosinophilic meningitis.

Double triggers, nasal induction of a Parkinson's disease mouse model

Animal models of Parkinson's disease (PD), a chronic and progressive neurodegenerative disease of the central nervous system (CNS), play a key role in investigating the pathogenesis and developing new therapeutic strategies of PD. However, this goal has been limited by certain weaknesses in the available animal models of PD, e.g., induction by either pro-inflammatory or neurotoxic reagents, or they are too time-/effort-consuming. Here, we report a double triggers, nasal induction of a PD mouse model that mimics the clinical, pathological features and pathogenesis of PD by intranasal (i.n.) administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) combined with lipopolysaccharide (LPS). After administration once every three days for 7 consecutive weeks, these mice displayed enhanced motor dysfunction, loss of dopaminergic neurons, α-synuclein accumulation, as well as activation of microglia and astrocytes in the substantia nigra pars compacta compared with mice that were administered MPTP or LPS alone. This study provides a novel and basic research tool for investigating the pathogenesis and therapeutic intervention of PD.

Soybean isoflavones prevent atrazine-induced neurodegenerative damage by inducing autophagy

Atrazine (ATR) is a widely used herbicide with documented dopaminergic (DAergic) neurotoxicity that can lead to a Parkinson's disease (PD)-like motor syndrome. However, there have been few studies on preventative interventions. The aim of the present study was to investigate the neuroprotective efficacy of soybean isoflavones (SI) and associated molecular mechanisms in a rat model of ATR-induced DAergic toxicity. Male Sprague-Dawley rats (6 weeks old) received daily intraperitoneal injection of SI (10, 50, or 100 mg/kg) or vehicle followed 1 h later by oral gavage of ATR (50 mg/kg) for 45 consecutive days. Open field and grip-strength tests indicated no differences in motor function among treatment groups. Alternatively, histopathology revealed neuronal damage in the striatum of rats receiving vehicle plus ATR that was ameliorated by SI pretreatment. SI attenuate ATR-induced oxidative stress (indicated by MDA accumulation and GSH depletion) and inflammatory damage (as evidenced by TNF-α and IL-6 elevation) in the substantia nigra. ATR increased expression of the pro-apoptotic factor Bax and reduced expression levels of the DA synthesis enzyme tyrosine hydroxylase (TH) and the anti-apoptotic factor Bcl-2 in the substantia nigra and striatum. All of these effects were reversed by SI pretreatment, suggesting that SI can inhibit ATR-induced apoptosis of DAergic neurons. ATR also inhibited autophagy in the substantial nigra as evidenced by LC3-II and Beclin-1 downregulation and increased expression of p62, whereas SI pretreatment reversed these effects, indicating autophagy induction. Furthermore, ATR increased the expression of mTOR and reduced the expression of phosphorylated S6 (p-S6) and BEX2 in the substantia nigra. Collectively, these findings suggest that SI can prevent ATR-mediated degeneration of DAergic neurons by inducing autophagy through an mTOR-dependent signaling pathway.

Transcriptomic analysis reveals new hippocampal gene networks induced by prolactin

Prolactin (Prl) is a pleiotropic hormone with multiple functions in several tissues and organs, including the brain. In the hippocampus, Prl has been implicated in several functions, including neuroprotection against excitotoxicity in lactating rats and in Prl-treated ovariectomized animals. However, the molecular mechanisms involved in Prl actions in the hippocampus have not been completely elucidated. The aim of this study was to analyse the hippocampal transcriptome of female Prl-treated ovariectomized rats. Transcriptomic analysis by RNASeq revealed 162 differentially expressed genes throughout 24 h of Prl treatment. Gene Ontology analysis of those genes showed that 37.65% were involved in brain processes that are regulated by the hippocampus, such as learning, memory and behaviour, as well as new processes that we did not foresee, such as glial differentiation, axogenesis, synaptic transmission, postsynaptic potential, and neuronal and glial migration. Immunodetection analysis demonstrated that Prl significantly modified microglial morphology, reduced the expression of Cd11b/c protein, and altered the content and location of the neuronal proteins Tau, Map2 and Syp, which are involved in axogenic and synaptic functions. This novel delineation of Prl activity in the hippocampus highlights its importance as a neuroactive hormone, opens a new avenue for understanding its actions and supports its participation in neuronal plasticity of this brain area.

Atrazine-xenobiotic nuclear receptor interactions induce cardiac inflammation and endoplasmic reticulum stress in quail (Coturnix coturnix coturnix)

Atrazine (ATR) is one of the most extensively used herbicide that eventually leaches into groundwater and surface water from agricultural areas. Exposure to ATR does harm to the health of human and animals, especially the heart. However, ATR exposure caused cardiotoxicity in bird remains unclear. To evaluate ATR-exerted potential cardiotoxicity in heart, quail were exposed with 0, 50, 250, and 500 mg/kg BW/day ATR by gavage treatment for 45 days. Cardiac histopathological alternation was observed in ATR-induced quail. ATR exposure increased the Cytochrome P450s and Cytochrome b5 contents, Cytochrome P450 (CYP) enzyme system (APND, ERND, AH, and NCR) activities and the expression of CYP isoforms (CYP1B1, CYP2C18, CYP2D6, CYP3A4, CYP3A7, and CYP4B1) in quail heart. The expression of nuclear xenobiotic receptors (NXRs) was also influenced in the heart by ATR exposure. ATR exposure significantly caused the up-regulation of pro-inflammatory cytokines (TNF-α, IL-6, NF-κB, and IL-8), down-regulation of anti-inflammatory cytokines (IL-10) expression levels and increased NO content and iNOS activity. The present research provides new insights into the mechanism that ATR-induced cardiotoxicity through up-regulating the expression levels of GRP78 and XBP-1s, triggering ER stress, activating the expression of IRE1α/TRAF2/NF-κB signaling pathway related factors (IRE1α, TRAF2, IKK, and NF-κB) and inducing an inflammatory response in quail hearts. In conclusion, ATR exposure could induce cardiac inflammatory injury via activating NXRs responses, disrupting CYP homeostasis and CYP isoforms transcription, altering NO metabolism and triggering ER stress and inflammatory response by activating IRE1α/TRAF2/NF-κB signaling pathway.

Inhibition of the hepatic Nlrp3 protects dopaminergic neurons via attenuating systemic inflammation in a MPTP/p mouse model of Parkinson's disease

Background

Parkinson’s disease (PD) is a neurodegenerative disorder with progressive loss of dopaminergic (DA) neurons. Systemic inflammation is shown to initiate and exacerbate DA neuronal degeneration in the substantia nigra. The infiltration and transformation of immune cells from the peripheral tissues are detected in and around the affected brain regions of PD patients. Our previous studies demonstrated the crucial role that microglial Nod-like receptor protein (NLRP) 3 inflammasome plays in the pathogenesis of PD. Nevertheless, the direct linkage between peripheral inflammation and DA neuron death remains obscure.

Methods

In the present study, we detected the NLRP3 expressions in the midbrain, liver, and bone marrow-derived macrophages in response to 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) acute and chronic challenge. We then used a tail vein injection of Nlrp3-siRNA wrapped with lentivirus to explore the potential influence of hepatic NLRP3 inflammasome-mediated inflammation on neuronal injury in a mouse model of PD via immunohistochemistry, ELISA, and Western blotting analysis.

Results

We showed that siNlrp3 downregulated the NLRP3 protein expression and inhibited the activation of NLRP3 inflammasomes in mice livers. The tail vein injection of LV3-siNlrp3 reduced the liver pro-inflammatory cytokine production, which subsequently alleviated MPTP-triggered microglial activation and DA neuron loss in the midbrain. These findings indicated that inhibition of hepatic NLRP3 inflammasome weakens inflammatory cytokines spreading into the brain and delays the progress of neuroinflammation and DA neuronal degeneration.

Conclusion

This study gives us an insight into the direct linkage between liver inflammation and DA neuron damage in the pathogenesis of PD and provides the potential target of NLRP3 for developing novel drugs for PD therapy.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1236-z) contains supplementary material, which is available to authorized users.

Fasudil Enhances Therapeutic Efficacy of Neural Stem Cells in the Mouse Model of MPTP-Induced Parkinson's Disease

Bone marrow-derived neural stem cells (NSCs) are ideal cells for cellular therapy because of their therapeutic potential for repairing and regenerating damaged neurons. However, the optimization of implanted cells and the improvement of microenvironment in the central nervous system (CNS) are still two critical elements for enhancing therapeutic effect. In the current study, we observed the combined therapeutic effect of NSCs with fasudil in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model and explored the possible cellular and molecular mechanisms. The results clearly show that combined treatment of NSCs with fasudil further improves motor capacity of PD mice, thus exerting double effect in treating MPTP-PD. The combined intervention more effectively protected dopaminergic (DA) neurons from loss in the substantia nigra pars compacta (SNpc), which may be associated with the increased number and survival of transplanted NSCs in the brain. Compared with the treatment of fasudil or NSCs alone, the combined intervention more effectively inhibited the activation and aggregation of microglia and astrocytes, displayed stronger anti-inflammatory and antioxidant effects, induced more neurotrophic factor NT-3, and affected the dynamic homeostasis of NMDA and AMPA receptors in MPTP-PD mice. Our study demonstrates that intranasal administration of NSCs, followed by fasudil administration, is a promising cell-based therapy for neuronal lesions.