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Intervertebral disc degeneration disease (IDD) is one of the leading causes of disability, and current therapies are ineffective. Phosphodiesterase 4B (PDE4B) plays essential roles in regulating the activation of the NLRP3 inflammasome. However, whether PDE4B or NLRP3 is involved in the development of IDD is unclear. This study sought to explore the role of PDE4B in IDD pathogenesis by in vivo and in vitro experiments. This results showed that PDE4B and NLRP3 were significantly upregulated in nucleus pulposus (NP) tissues from IDD-related human patients. Deletion of PDE4B in the NP resulted in downregulated JNK and NLRP3. Aberrant PDE4B expression enhanced the phosphorylation of JNK and NLRP3 expression. Furthermore, genetic ablation of the pde4b gene delayed IDD pathogenesis, and PDE4 inhibitor also can reverse the IDD pathogenesis. Our study showed that aberrant PDE4B activation in NP tissues induces pathological changes in IDD, phosphorylation of JNK and NLRP3 are involved in this process, and inhibition of aberrant PDE4B activity is a potential therapeutic strategy for IDD. [ABSTRACT FROM AUTHOR]

Aim: The important role of phosphodiesterase 4B (PDE4B) inhibition on lipopolysaccharide (LPS)-induced ALI has been reported. However, the corresponding mechanisms remain unclear. In the present study, the relationship between PDE4B and phosphorylation of p65 (Ser468) in LPS-induced injury by in vivo and in vitro models was investigated. Methods and results: pde4b+/+ mice, inflammation was significantly up-regulated after LPS stimulation, including the highest number of immune cells, especially neutrophils, and the level of pro-inflammatory cytokines measured by ELISA, while all those were blunted in pde4b−/− mice. Moreover, pde4b−/− mice improved the expression of PKA in lung tissues and down-regulated the IKKα/β-NF-κB p65 signaling determined by western blotting. In vitro experiments in MH-S cells revealed that siRNA-mediated specific silence of PDE4B expression resulted in a decrease of inflammatory markers and phosphorylation of p65 at Ser468 after LPS treatment, but overexpressing PDE4B increased the inflammation and phosphorylation of p65 at Ser468. In MH-S cells, luciferase analysis indicated that PDE4B acts as a positive regulator of p65 in inflammation. PKA inhibitor (H-89) increased pP65 and PDE4B expression, while PKA activator (6-BZ-cAMP) showed the opposite effect in macrophages. More importantly, the proteasome-mediated degradation of cAMP effector was negatively correlated with the phosphorylation of p65 (Ser468) and PDE4B expression in MH-S cells. Conclusions: PDE4B plays a critical role in orchestrating LPS-induced acute lung inflammation by cAMP/PKA axis-mediated phosphorylation of p65. Schematic model of PDE4B in the LPS-induced inflammatory signaling process. In pde4b+/+ mice, LPS binding with TLR4 receptor and down-regulates cAMP/PKA thus modulates NF-κB/pP65 phosphorylation at Ser468 site, leading to the inflammatory response: release of TNF-α, IL-6, and IL-1β; neutrophil infiltration. PDE4B knockout can decrease cAMP/PKA and phosphorylation of IKK and p65 (Ser468), down-regulate the cells recruitment and the release of inflammatory cytokines in ALI mouse model and macrophages. [ABSTRACT FROM AUTHOR]

Ulcerative colitis (UC) is a form of inflammatory bowel disease, which manifests as irritation or swelling and sores in the large intestine in a relapsing and remitting manner. In a dextran sulfate sodium sulfate (DSS)-induced UC model in female mice, we found that the levels of cyclic guanosine monophosphate (cGMP) are reduced, while the expression of phosphodiesterase 9A (PDE9A) is highest among all phosphodiesterase (PDEs). Since PDE9 has the highest affinity toward cGMP, we evaluated the selective PDE9 inhibitor PF-04447943 (PF) as a potential candidate for UC treatment. PF has been extensively studies in cognitive function and in sickle cell disease, but not in models for inflammatory bowel disease (IBD). Therefore, we used female C57BL/6 mice treated with 3% DSS alone or cotreated with PF or sulfasalazine (SASP) to study the body weight, colon length, histopathology, and measure superoxide dismutase (SOD), malondialdehyde (MDA), and cGMP level, as well as cytokines such as tumor necrosis factor-alpha (TNF-a), interleukin-6 (IL-6), interleukin-17 (IL-17), interleukin-12/23 (IL-12/23), interleukin-10 (IL-10), and pathways including nuclear factor kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3), and inflammasome activation. In addition, the number of dendritic cells (DC) and regulatory T cells (Treg cell) was assessed in the spleen, lymph node, and colon using flow cytometry. DSS reduced the number of goblet cells, decreased colon lengths and body weights, all of them were attenuated by PF treatment. It also suppressed the elevated level of inflammatory cytokines and increased level the anti-inflammatory cytokine, IL-10. PF treatment also reduced the DSS-induced inflammation by suppressing oxidative stress, NF-κB, STAT3, and inflammasome activation, by upregulating nuclear factor erythroid 2-related factor 2 (Nrf-2) and its downstream proteins via extracellular signal-regulated kinase (ERK) phosphorylation. Importantly, PF reversed imbalance in Treg/T helper 17 cells (Th17) cells ratio, possibly by regulating dendritic cells and Treg developmental process. In summary, this study shows the protective effect of a PDE9A inhibitor in ulcerative colitis by suppressing oxidative stress and inflammation as well as reversing the Treg/Th17 cells imbalance. [ABSTRACT FROM AUTHOR]

Context:Immune dysregulation has been implicated in the pathogenesis of many diseases. Macrophages play a crucial role contributing to the onset, progression, and resolution of inflammation. Macrophage inflammatory mediators are of considerable interest as potential targets to treat inflammatory diseases. Objective:The present study was conducted to elucidate the anti-inflammatory mechanism of 2′,4-dihydroxy-3′,4′,6′-trimethoxychalcone (1), the major chalcone isolated fromChromolaena odorata(L.) R.M.King & H.Rob, against lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages. Materials and methods:Cell viability, nitric oxide (NO), and proinflammatory cytokines of LPS-activated RAW 264.7 cells were measured by MTT, Griess, and ELISA assays, respectively. Cell lysates were subjected to Western blotting for investigation of protein expression. Results and discussion:Treatment with the major chalcone1significantly attenuated the production of NO and proinflammatory cytokines, tumor necrosis factor-α, interleukin-1β, and interleukin-6 in a dose-dependent manner. The chalcone suppressed nuclear factor-κB (NF-κB) stimulation by preventing activation of inhibitor κB kinase (IKK) α/β, degradation of inhibitor κB (IκB) α, and translocation of p65 NF-κB into the nucleus. Additionally, the chalcone markedly repressed the phosphorylation of p38 mitogen-activated protein kinase (MAPK), but no further inhibition was detected for c-Jun N-terminal activated kinases or extracellular regulated kinases. Thus, suppression of NF-κB and p38 MAPK activation may be the core mechanism underlying the anti-inflammatory activity of 2′,4-dihydroxy-3′,4′,6′-trimethoxychalcone (1). Conclusion:These findings provide evidence that 2′,4-dihydroxy-3′,4′,6′-trimethoxychalcone (1) possesses anti-inflammatory activity via targeting proinflammatory macrophages. This anti-inflammatory chalcone is a promising compound for reducing inflammation. [ABSTRACT FROM PUBLISHER]

Background: Targeting inflammatory macrophages and their products is an effective method for controlling inflammation. The pyrazole analog of curcumin (curcumin pyrazole, PYR) has been reported to possess superior anti-inflammatory activity to curcumin (CUR). However, the role of PYR anti-inflammatory activity in macrophages has not yet been elucidated., Objective: To examine the anti-inflammatory effects of PYR and CUR in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages and determine the role of mitogen-activated protein kinases (MAPK) in their activity., Methods: Nitrite level was investigated by the Griess assay. The expression of inducible nitric oxide (NO) synthase, cyclooxygenase-2 (COX-2), and MAPK proteins were analyzed by western blot analysis. The pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay., Results: LPS-induced NO secretion in RAW 264.7 macrophages was potently inhibited by PYR (IC50 = 3.7 ± 0.16 μM), at a higher efficacy than CUR (IC50 = 11.0 ± 0.59 μM). Treatment with identical concentrations of PYR and CUR demonstrated that PYR drastically inhibited iNOS and COX-2 expression, whereas CUR only blocked COX-2. PYR reduced the LPS-induced secretion of TNF-α to a greater extent than CUR and both similarly reduced IL-1β and IL-6 levels. Activation of c-Jun N-terminal kinase (JNK) MAPK was significantly decreased in LPS-activated RAW 264.7 macrophages upon PYR but not CUR treatment., Conclusion: PYR exhibited a more potent anti-inflammatory activity than CUR. This activity is partly mediated by PYR-depended inhibition of the JNK signaling pathway and underscores the utility of PYR as an anti-inflammatory agent in macrophages.