Cryptotanshinone inhibits RANKL-induced osteoclastogenesis by regulating ERK and NF-κB signaling pathways

Osteoporosis (OS) is one of the most common healthy problems characterized by low bone mass. Osteoclast, the primary bone-resorbing cell, is responsible for destructive bone diseases including osteoporosis (OS). Cryptotanshinone (CTS), an active component extracted from the root of Salvia miltiorrhiza bunge, has been shown to prevent the destruction of cartilage and the thickening of subchondral bone in mice osteoarthritis models. However, its molecular mechanism in osteoclastogenesis needs to be determined. The aim of the current study was to explore the effect of CTS on osteoclastogenesis and further evaluate the underlying mechanism. Our results showed that CTS inhibited receptor activator of NF-κB ligand (RANKL)-induced the increase in tartrate-resistant acid phosphatase (TRAP) activity in bone marrow–derived macrophages (BMMs). In addition, the expressions of osteoclastogenesis-related marker proteins and nuclear factor of activated T-cells (NFAT) activation were suppressed by CTS treatment in BMMs. Furthermore, CTS attenuated RANKL-induced ERK phosphorylation and NF-κB activation in BMMs. These findings indicated that CTS inhibited RANKL-induced osteoclastogenesis by inhibiting ERK phosphorylation and NF-κB activation in BMMs. Thus, CTS may function as an inhibitor of osteoclastogenesis and may be considered as an alternative medicine for the prevention and treatment of OS.     

Overexpression of Sirtuin2 prevents high glucose-induced vascular endothelial cell injury by regulating the p53 and NF-κB signaling pathways

Objectives

To investigate the potential role and underlying mechanism of Sirtuin2 (SIRT2) in regulating high glucose (HG)-induced vascular endothelial cell injury by using human umbilical vein endothelial cells (HUVECs).

Results

SIRT2 mRNA and protein expression levels were decreased in HG-treated HUVECs. SIRT2 overexpression increased viability, decreased apoptosis and reduced levels of reactive oxygen species in HG-treated HUVECs. SIRT2 overexpression decreased TNF-α expression (146.5 ± 22.8 pg TNF-α ml^?1) relative to that in the empty vector group (263.5 ± 18.5 pg TNF-α ml^?1) and decreased MCP-1 expression (63.8 ± 9.85 pg MCP-1 ml^?1) relative to that in the empty vector group (105.8 ± 8.5 pg MCP-1 ml^?1). SIRT2 overexpression decreased the acetylation of p53 by 33% and decreased the acetylation of NF-κB p65 by 58% in HG-treated HUVECs.

Conclusion

SIRT2 prevents HG-induced vascular endothelial cell injury through suppressing the p53 and NF-κB signaling pathways.

     

Mindin deficiency alleviates renal fibrosis through inhibiting NF-κB and TGF-β/Smad pathways

Renal fibrosis acts as a clinical predictor in patients with chronic kidney disease and is characterized by excessive extracellular matrix (ECM) accumulation. Our previous study suggested that mindin can function as a mediator for liver steatosis pathogenesis. However, the role of mindin in renal fibrosis remains obscure. Here, tumour necrosis factor (TGF)-β-treated HK-2 cells and global mindin knockout mouse were induced with renal ischaemia reperfusion injury (IRI) to test the relationship between mindin and renal fibrosis. In vitro, mindin overexpression promoted p65—the hub subunit of the NF-κB signalling pathway—translocation from the cytoplasm into the nucleus, resulting in NF-κB pathway activation in TGF-β-treated HK-2 cells. Meanwhile, mindin activated the TGF-β/Smad pathway, thereby causing fibrotic-related protein expression in vitro. Mindin^−/− mice exhibited less kidney lesions than controls, with small renal tubular expansion, inflammatory cell infiltration, as well as collagen accumulation, following renal IRI. Mechanistically, mindin^−/− mice suppressed p65 translocation and deactivated NF-κB pathway. Simultaneously, mindin disruption inhibited the TGF-β/Smad pathway, alleviating the expression of ECM-related proteins. Hence, mindin may be a novel target of renal IRI in the treatment of renal fibrogenesis.     

Reduning injection ameliorates paraquat-induced acute lung injury by regulating AMPK/MAPK/NF-κB signaling

Reduning injection (RDN), a patented Chinese medicine, is broadly used for common cold and lung infection in clinic, but the mechanism underlying its effects on inflammation-related pulmonary injury remains unclear. Paraquat (PQ, bolus 15 mg/kg dose, ip) was administered for acute lung injury induction in mice, which were orally administered dexamethasone (2 mg/kg) or RDN (50 and 100 mg/kg/day) for 5 days. After treatment, plasma and lung tissue samples from the euthanized animals were obtained and analyzed by histological, biochemical and immunoblot assays. Histological observation demonstrated RDN alleviated PQ-induced lung damage. Meanwhile, RDN suppressed myeloperoxidase (MPO) activity, reduced the wet/dry (W/D) ratio and decreased the amounts of total leukocytes and neutrophils. Treatment also markedly decreased the amounts of malondialdehyde, MPO, and inflammatory cytokines while increasing superoxide dismutase activity in comparison with the PQ group. In immunoblot, RDN blocked the phosphorylation levels of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), JNK, ERK, p38, inhibitor of nuclear factor κB kinase and nuclear factor-κB (NF-κB) in lung tissue specimens in PQ-challenged animals, which was further verified in vitro. The above data indicated protective effects for RDN in PQ-induced lung damage, possibly through inhibition of the AMPK/MAPK/NF-κB pathway.     

Polysaccharides from Dicliptera chinensis ameliorate liver disturbance by regulating TLR-4/NF-κB and AMPK/Nrf2 signalling pathways

The purpose of this study was to alleviate liver disturbance by applying polysaccharides from Dicliptera chinensis (DCP) to act on the adenosine monophosphate–activated protein kinase/ nuclear factor erythroid 2-related factor 2 (AMPK/ Nrf2) oxidative stress pathway and the Toll-like receptor 4 (TLR-4)/ nuclear factor kappa-B (NF-κB) inflammatory pathway and to establish an in vivo liver disturbance model using male C57BL/6J and TLR-4 knockout (^−/−) mice. For this, we evaluated the expression levels of SREBP-1 and Nrf2 after silencing the expression of AMPK using siRNA technology. Our results show that with regard to the TLR-4/ NF-κB inflammatory pathway, DCP inhibits TLR-4, up-regulates the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), reduces the expression of phospho(p)-NF-κB and leads to the reduction of downstream inflammatory factors, such as tumour necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1β, thereby inhibiting the inflammatory response. Regarding the AMPK/ Nrf2 oxidative stress pathway, DCP up-regulates the expression of p-AMPK and Nrf2, in addition to regulating glucose and lipid metabolism, oxidative stress and ameliorating liver disturbance symptoms. In summary, our study shows that DCP alleviates liver disturbances by inhibiting mechanisms used during liver inflammation and oxidative stress depression, which provides a new strategy for the clinical treatment of liver disturbance.     

Astragalus polysaccharides alleviates LPS-induced inflammation via the NF-κB/MAPK signaling pathway

Early weaning usually causes intestinal disorders, enteritis, and diarrhea in young animals and human infants. Astragalus polysaccharides (APS) possesses anti-inflammatory activity. To study the anti-inflammatory mechanisms of APS and its potential effects on intestinal health, we performed an RNA sequencing (RNA-seq) study in lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cells (IPEC-J2) in vitro. In addition, LPS-stimulated BALB/c mice were used to study the effects of APS on intestinal inflammation in vivo. The results from the RNA-seq analysis show that there were 107, 756, and 5 differentially expressed genes in the control versus LPS, LPS versus LPS+APS, and control versus LPS+APS comparison groups, respectively. The results of Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways play significant roles in the regulation of inflammatory factors and chemokine expression by APS. Further verification of the above two pathways by using western blot and immunofluorescence analysis revealed that the gene expression levels of the phosphorylated p38 MAPK, ERK1/2, and NF-κB p65 were inhibited by APS, while the expression of IκB-α protein was significantly increased (p < .05), indicating that APS inhibits the production of inflammatory factors and chemokines by the inhibition of activation of the MAPK and NF-κB inflammatory pathways induced by LPS stimulation. Animal experiments further demonstrated that prefeeding APS in BALB/c mice can alleviate the expression of the jejunal inflammatory factors interleukin 6 (IL-6), IL-Iβ, and tumor necrosis factor-α induced by LPS stimulation and improve jejunal villus morphology.     

Anesthetic propofol reduces endotoxic inflammation by inhibiting reactive oxygen species-regulated Akt/IKKβ/NF-κB signaling

Background

Anesthetic propofol has immunomodulatory effects, particularly in the area of anti-inflammation. Bacterial endotoxin lipopolysaccharide (LPS) induces inflammation through toll-like receptor (TLR) 4 signaling. We investigated the molecular actions of propofol against LPS/TLR4-induced inflammatory activation in murine RAW264.7 macrophages.

Methodology/Principal Findings

Non-cytotoxic levels of propofol reduced LPS-induced inducible nitric oxide synthase (iNOS) and NO as determined by western blotting and the Griess reaction, respectively. Propofol also reduced the production of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-10 as detected by enzyme-linked immunosorbent assays. Western blot analysis showed propofol inhibited LPS-induced activation and phosphorylation of IKKβ (Ser180) and nuclear factor (NF)-κB (Ser536); the subsequent nuclear translocation of NF-κB p65 was also reduced. Additionally, propofol inhibited LPS-induced Akt activation and phosphorylation (Ser473) partly by reducing reactive oxygen species (ROS) generation; inter-regulation that ROS regulated Akt followed by NF-κB activation was found to be crucial for LPS-induced inflammatory responses in macrophages. An in vivo study using C57BL/6 mice also demonstrated the anti-inflammatory properties against LPS in peritoneal macrophages.

Conclusions/Significance

These results suggest that propofol reduces LPS-induced inflammatory responses in macrophages by inhibiting the interconnected ROS/Akt/IKKβ/NF-κB signaling pathways.     

Emodin suppresses oxaliplatin-induced neuropathic pain by inhibiting COX2/NF-κB mediated spinal inflammation

Oxaliplatin (OXA) is a common chemotherapy drug for colorectal, gastric, and pancreatic cancers. The anticancer effect of OXA is often accompanied by neurotoxicity and acute and chronic neuropathy. The symptoms present as paresthesia and pain which adversely affect patients' quality of life. Herein, five consecutive intraperitoneal injections of OXA at a dose of 4 mg/kg were used to mimic chemotherapy. OXA administration induced mechanical allodynia, activated spinal astrocytes, and increased inflammatory response. To develop an effective therapeutic measure for OXA-induced neuropathic pain, emodin was intrathecally injected into OXA rats. Emodin developed an analgesic effect, as demonstrated by a significant increase in the paw withdrawal threshold of OXA rats. Moreover, emodin treatment reduced the pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-1β) which upregulated in OXA rats. Furthermore, autodock data showed four hydrogen bonds were formed between emodin and cyclooxygenase-2 (COX2), and emodin treatment decreased COX2 expression in OXA rats. Cell research further proved that emodin suppressed nuclear factor κB (NF-κB)-mediated inflammatory signal and reactive oxygen species level. Taken together, emodin reduced spinal COX2/NF-κB mediated inflammatory signal and oxidative stress in the spinal cord of OXA rats which consequently relieved OXA-induced neuropathic pain.     

Regulation of skin inflammation and angiogenesis by EC-SOD via HIF-1α and NF-κB pathways

Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that breaks down superoxide anion into oxygen and hydrogen peroxide in extracellular spaces and plays key roles in controlling pulmonary and vascular diseases in response to oxidative stresses. We aimed to investigate the role of EC-SOD in angiogenesis and inflammation in chronic inflammatory skin disorders such as psoriasis. Overexpressed EC-SOD reduced expression of angiogenic factors and proinflammatory mediators in hypoxia-induced keratinocytes and in ultraviolet B-irradiated mice, whereas the expression of the antiangiogenic factor tissue inhibitor of metalloproteinase-1 and anti-inflammatory cytokine interleukin-10 were increased. EC-SOD decreased new vessel formation, epidermal edema, and inflammatory cell infiltration in UVB-irradiated transgenic mice. Moreover, cells treated with recombinant human EC-SOD showed inhibited endothelial tube formation and cell proliferation. Overall, the antiangiogenic and anti-inflammatory effects of EC-SOD might be due to suppression of hypoxia-inducible factor-1α, protein kinase C, and nuclear factor-κB expression. Furthermore, EC-SOD expression in tissue from psoriasis patients was markedly decreased in psoriatic lesional and nonlesional skins from psoriasis patients in comparison to normal skin from healthy volunteers. Together, these results suggest that EC-SOD may provide a novel therapeutic approach to treating angiogenic and inflammatory skin diseases such as psoriasis.     

Salidroside promotes rat spinal cord injury recovery by inhibiting inflammatory cytokine expression and NF-κB and MAPK signaling pathways

Spinal cord injury (SCI) is a public health problem in the world. The SCI usually triggers an excessive inflammatory response that brings about a secondary tissue wreck leading to further cellular and organ dysfunction. Hence, there is great potential of reducing inflammation for therapeutic strategies of SCI. In this study, we aim to investigate if Salidroside (SAD) exerts an anti-inflammatory effect and promotes recovery of motor function on SCI through suppressing nuclear factor-κB (NF-κB) and the mitogen-activated protein kinase (MAPK) pathways. In vitro, real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) were used to examine the inhibitory effect of SAD on the expression and release of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) activated by lipopolysaccharide (LPS) in astrocytes. In addition, SAD was found to inhibit NF-κB, p38 and extracellular-regulated protein kinases (ERK) signaling pathways by western blot analysis. Further, in vivo study showed that SAD was able to improve hind limb motor function and reduce tissue damage accompanied by the suppressed expression of inflammatory cytokines IL-1β, IL-6, and TNF-α. Overall, SAD could reduce the inflammatory response and promote motor function recovery in rats after SCI by inhibiting NF-κB, p38, and ERK signaling pathways.     

Mechanical stress protects against osteoarthritis via regulation of the AMPK/NF-κB signaling pathway

Mechanical stress plays a key role in regulating cartilage degradation in osteoarthritis (OA). The aim of this study was to evaluate the effects and mechanisms of mechanical stress on articular cartilage. A total of 80 male Sprague-Dawley rats were randomly divided into eight groups (n = 10 for each group): control group (CG), OA group (OAG), and CG or OAG subjected to low-, moderate-, or high-intensity treadmill exercise (CL, CM, CH, OAL, OAM, and OAH, respectively). Chondrocytes were obtained from the knee joints of rats; they were cultured on Bioflex 6-well culture plates and subjected to different durations of cyclic tensile strain (CTS) with or without exposure to interleukin-1β (IL-1β). The results of the histological score, immunohistochemistry, enzyme-linked immunosorbent assay, and western-blot analyses indicated that there were no differences between CM and CG, but OAM showed therapeutic effects compared with OAG. However, CH and OAH experienced more cartilage damage than CG and OAG, respectively. CTS had no therapeutic effects on collagen II of normal chondrocytes, which is consistent with findings after treadmill exercise. However, CTS for 4 hr could alleviate the chondrocyte damage induced by IL-1β by activating AMP-activated protein kinase (AMPK) phosphorylation and suppressing nuclear translocation of nuclear factor (NF)-κB p65. Our findings indicate that mechanical stress had no therapeutic effects on normal articular cartilage and chondrocytes; mechanical stress only caused damage with excessive stimulation. Still, moderate biomechanical stress could reduce sensitization to the inflammatory response of articular cartilage and chondrocytes through the AMPK/NF-κB signaling pathway.