Anti-inflammatory Effects of Dopamine in Lipopolysaccharide (LPS)-stimulated RAW264.7 Cells via Inhibiting NLRP3 Inflammasome Activation.

Dopamine (DA) is a neurotransmitter and chemical mediator, and DA receptors (particularly DRD1) are present on the majority of immune cells. The aim of this study was to investigate the effects of DA on lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW264.7 cells. Cells were exposed to DA (10*-3, 10*-4 and 10*-5M) for 2 hr prior, with or without LPS (1μg/ml) for 6hr. Additionally, DA and NLRP3 inhibitor, MCC950 had treated LPS-stimulated RAW264.7 cells. CCK8 assays were used for the assessment of cell viability and Quantitative real-time PCR (qRT-PCR) and western blot analysis were used to examine mRNA and protein expression levels, respectively. Our results reveal that DA reduces the mRNA and protein expression of tumor necrosis factor-a (TNF-α), interleukin-6 (IL-6) and interleukin (1L), (IL-1β) in RAW 264.7 cells stimulated with LPS. DA also inhibited the mRNA and protein expression levels of nitric oxide synthase (iNOS) and downregulated NLRP3 and caspase-1 expression. The administration of DA and NLRP3 inhibitor, MCC950 played a synergistic role in suppressing NLRP3 activity. Taken together, these findings demonstrate that DA displays potent anti-inflammatory effects that are mediated by the suppression of pro-inflammatory mediators (IL-1β, IL-6, TNF-α), cytokines (iNOS) and the NLRP3 inflammasome activation. Improvement of DA correlated with its effect on NLRP3 activation. Thus, DA and agonists of DRD1, as a functional molecule that bridges the neuronal and immune systems, may represent effective strategies for limiting pathological inflammation.

Liu A ，Ding S 《-》

GEN-27 exhibits anti-inflammatory effects by suppressing the activation of NLRP3 inflammasome and NF-κB pathway.

Prolonged inflammation and deregulated cytokine production are associated with diversified inflammatory diseases. Genistein (GEN), the active and predominant isoflavonoid in dietary soybean, possesses anti-inflammatory activity. Our study aimed to assess the anti-inflammatory effects of GEN-27, a derivative of GEN, as well as explore the potential molecular mechanisms using lipopolysaccharide (LPS)-induced RAW264.7 cells. In our study, we demonstrated that GEN-27 administration (1, 5, or 10 μM) dose-dependently inhibited nitrite and nitric oxide (NO) levels in LPS-stimulated RAW264.7 cells. Also, GEN-27 suppressed the release of LPS-induced pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-18. Moreover, GEN-27 attenuated LPS-induced inducible NO synthase (iNOS), and cyclooxygenase-2 (COX-2) expressions at messenger RNA and protein levels, and reversed the promoter activity of iNOS in RAW264.7 cells. Mechanistically, GEN-27 abated LPS-induced reactive oxygen species production, as well as mitigated LPS-induced increase of caspase 1 activity and the protein levels of NOD-like receptor 3 (NLRP3), anti-apoptosis-associated speck-like protein-containing a CRAD (ASC), and caspase 1 in RAW264.7 cells in a dose-dependent manner. Similarly, GEN-27 dose-dependently weakened adenosine triphosphate-induced NLRP3 and IL-1β in RAW264.7 cells. In addition, GEN-27 treatment significantly suppressed LPS-induced phosphorylation of nuclear factor-κB (NF-κB) p65 and alleviated LPS-induced increase of transcriptional activity of NF-κB in RAW264.7 cells. In summary, these results revealed that GEN-27 exhibited anti-inflammatory effects by suppressing the activation of NLRP3 inflammasome and NF-κB pathway, suggesting that GEN-27 may be served as a promising therapeutic agent for the prevention and therapy of inflammatory-associated diseases.

Hu M ，Li X ，Zhang J ，Yuan Z ，Fu Y ，Ma X ，Ren N ... -  《-》

Hydrogen-Rich Saline Attenuated Subarachnoid Hemorrhage-Induced Early Brain Injury in Rats by Suppressing Inflammatory Response: Possible Involvement of NF-κB Pathway and NLRP3 Inflammasome.

Shao A ，Wu H ，Hong Y ，Tu S ，Sun X ，Wu Q ，Zhao Q ，Zhang J ，Sheng J ... -  《-》

Aloe vera downregulates LPS-induced inflammatory cytokine production and expression of NLRP3 inflammasome in human macrophages.

Budai MM ，Varga A ，Milesz S ，Tőzsér J ，Benkő S ... -  《-》

HBV inhibits LPS-induced NLRP3 inflammasome activation and IL-1β production via suppressing the NF-κB pathway and ROS production.

Hepatitis B virus (HBV) has developed strategies to evade immune responses. However, the mechanisms involved remain unclear. The NLRP3 inflammasome plays crucial roles in antiviral host defense and its downstream factor IL-1β has been shown to inhibit HBV infection in vivo. This study aims to assess whether HBV can affect the NLRP3 inflammasome signaling pathways and shed light on the underlying mechanisms HBV utilizes to evade host innate immune responses. HBV inhibition of the lipopolysaccharide (LPS)-induced NLRP3 inflammasome activation was evaluated by Western blot, quantitative RT-PCR, flow cytometry and immunofluorescence. Kupffer cells expressed significantly more NLRP3 and IL-1β after LPS stimulation; whereas, chronic HBV infection suppressed LPS-induced NLRP3 and pro-IL-1β expression as well as IL-1β maturation. This inhibitory activity is mediated by HBeAg, and is involved in the inhibition of NF-κB signal pathway and reactive oxygen species (ROS) production. The inhibitory effect of HBeAg was confirmed in patients with chronic hepatitis B (CHB) and hepatocellular carcinoma by comparing the levels of IL-1β and NLRP3-related proteins in para-carcinoma tissues from HBeAg-positive or negative patients. Moreover, chronic HBV infection increases the susceptibility of mice to S. typhimurium infection, possibly via inhibiting the NLRP3 inflammasome activation and IL-1β production. HBeAg inhibits LPS-induced NLRP3 inflammasome activation and IL-1β production via suppressing NF-κB pathway and ROS production. This finding provides a novel mechanism for HBV-mediated suppression of innate immune responses, and identifies new therapeutic targets for chronic HBV infection and related diseases. HBeAg suppresses LPS-induced NLRP3 inflammasome activation and IL-1β production in two ways, one is to repress NLRP3 and pro-IL-1β expression via inhibiting NF-κB phosphorylation, and the other is to repress caspase-1 activation and IL-1β maturation via inhibiting ROS production. This effect contributes to the HBV persistence and immune tolerance.

Yu X ，Lan P ，Hou X ，Han Q ，Lu N ，Li T ，Jiao C ，Zhang J ，Zhang C ，Tian Z ... -  《-》