A novel compound C12 inhibits inflammatory cytokine production and protects from inflammatory injury in vivo

Immunomodulatory Effects of Heme Oxygenase-1 in Kidney Disease

Kidney disease is a general term for heterogeneous damage that affects the function and the structure of the kidneys. The rising incidence of kidney diseases represents a considerable burden on the healthcare system, so the development of new drugs and the identification of novel therapeutic targets are urgently needed. The pathophysiology of kidney diseases is complex and involves multiple processes, including inflammation, autophagy, cell-cycle progression, and oxidative stress. Heme oxygenase-1 (HO-1), an enzyme involved in the process of heme degradation, has attracted widespread attention in recent years due to its cytoprotective properties. As an enzyme with known anti-oxidative functions, HO-1 plays an indispensable role in the regulation of oxidative stress and is involved in the pathogenesis of several kidney diseases. Moreover, current studies have revealed that HO-1 can affect cell proliferation, cell maturation, and other metabolic processes, thereby altering the function of immune cells. Many strategies, such as the administration of HO-1-overexpressing macrophages, use of phytochemicals, and carbon monoxide-based therapies, have been developed to target HO-1 in a variety of nephropathological animal models, indicating that HO-1 is a promising protein for the treatment of kidney diseases. Here, we briefly review the effects of HO-1 induction on specific immune cell populations with the aim of exploring the potential therapeutic roles of HO-1 and designing HO-1-based therapeutic strategies for the treatment of kidney diseases.

Dienone Compounds: Targets and Pharmacological Responses

The biological responses to dienone compounds with a 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore have been studied extensively. Despite their expected general thiol reactivity, these compounds display considerable degrees of tumor cell selectivity. Here we review in vitro and preclinical studies of dienone compounds including b-AP15, VLX1570, RA-9, RA-190, EF24, HO-3867, and MCB-613. A common property of these compounds is their targeting of the ubiquitin–proteasome system (UPS), known to be essential for the viability of tumor cells. Gene expression profiling experiments have shown induction of responses characteristic of UPS inhibition, and experiments using cellular reporter proteins have shown that proteasome inhibition is associated with cell death. Other mechanisms of action such as reactivation of mutant p53, stimulation of steroid receptor coactivators, and induction of protein cross-linking have also been described. Although unsuitable as biological probes due to widespread reactivity, dienone compounds are cytotoxic to apoptosis-resistant tumor cells and show activity in animal tumor models.

Attenuation of vincristine-induced neuropathy by synthetic cyclohexenone-functionalized derivative in mice model

Vincristine (VCR) is a well-known anticancer drug which frequently induced painful neuropathy and impairs the quality of life of patients. The present study was designed to investigate the alleviative potential of a novel cyclohexenone derivative (CHD), i.e., ethyl 6-(4-methoxyphenyl)-2-oxo-4-phenylcyclohexe-3-enecarboxylate, against VCR-induced neuropathic pain in mice model. VCR was administered intraperitoneally for 10 days in two cycles to induce neuropathic pain. Static and dynamic mechanical allodynia was evaluated using von Frey hair filaments and cotton buds, respectively. Paw thermal hyperalgesia was determined through a hot plate analgesiometer. The tail cold immersion hyperalgesia and paw cold allodynia were determined by available standard protocols. The formalin nociception was induced via subplantar injection of formalin. The antioxidant potential was evaluated via 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity. The outcome of this study revealed that CHD (30-45 mg/kg) and gabapentin (75 mg/kg) significantly enhanced the paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) in static and dynamic allodynia, respectively, and increased the PWL in thermal hyperalgesia and tail withdrawal latency (TWL) as compared to the VCR-treated group. CHD significantly augmented the paw withdrawal duration (PWD) in paw cold allodynia, while the same compound only increased the paw elevation and paw licking in the delayed phase of formalin nociception. Moreover, CHD significantly inhibited the DPPH free radical scavenging action (IC₅₀ = 56), butylated hydroxytoluene (BHT) (IC₅₀ = 39), and ascorbic acid (IC₅₀ = 2.93). In conclusion, CHD exhibited a profile of potential attenuative effect against the VCR-induced neuropathic pain which might be attributed to its possible antinociceptive and antioxidant effect.

Physalin B Suppresses Inflammatory Response to Lipopolysaccharide in RAW264.7 Cells by Inhibiting NF-κB Signaling

Physalin B from Physalis angulata L. (Solanaceae) is a naturally occurring secosteroid with multiple biological activities. But its anti-inflammatory activity and mechanism remain unclear. Physalin B effects on RAW264.7 macrophages stimulated by lipopolysaccharide (LPS) were observed in this study. The expression and secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) induced by LPS were significantly inhibited by physalin B. Meanwhile, the NF-κB nuclear translocation induced by LPS was inhibited by physalin B. The anti-inflammatory effects of physalin B could not be inhibited by mifepristone (RU486), the blocker of glucocorticoid receptor. In conclusion, physalin B can suppress inflammatory response to LPS in macrophages by inhibiting the production of inflammatory cytokines via NF-κB signaling.

Inhibitory effects of Dianthi Herba ethanolic extract on inflammatory and nociceptive responses in murine macrophages and mouse models of abdominal writhing and ear edema

ETHNOPHARMACOLOGICAL RELEVANCE

Dianthi Herba is a traditional herbal medicine used to treat inflammatory-related diseases including acute pyelonephritis, cystitis, laryngopharyngitis, and urethritis.

AIM OF THE STUDY

We investigated the effects of Dianthi Herba ethanolic extract (DH) on lipopolysaccharide (LPS)-mediated inflammatory responses in murine macrophages including RAW 264.7 cell line and mouse peritoneal macrophages as well as nociceptive and edema mouse models.

MATERIALS AND METHODS

The biological effects of DH on inflammatory cytokine, mediator, and related protein production were assessed using enzyme-linked immunosorbent assay (ELISA), Western blotting, and real-time reverse transcription-polymerase chain reaction (real-time RT-PCR). Additionally, Western blotting was performed to investigate intracellular signaling pathways, and the anti-nociceptive activity of three doses of DH (100, 200, and 300mg/kg) against acetic acid-induced writhing responses and its inhibitory effects on xylene-induced ear edema were researched in mice through oral administration.

RESULTS

DH treatment significantly inhibited nitric oxide (NO) secretion and inflammatory cytokine production in RAW 264.7 cells and mouse peritoneal macrophages and induced heme oxygenase (HO)-1 expression. DH strongly inhibited the transcriptional activity of nuclear factor (NF)-κB and phosphorylation of mitogen-activated protein kinases (MAPK) in LPS-stimulated macrophages. Meanwhile, DH exerted anti-nociceptive effects on writhing responses and anti-edema effects in mice.

CONCLUSION

We confirmed the anti-inflammatory activities and inhibitory mechanism of DH in macrophages and clarified its inhibitory effects in vivo. These findings illustrate the therapeutic potential of DH as a natural anti-inflammatory agent.

Maydis Stigma Elicits Analgesia and Blocks Edema in Mice and Inhibits Inflammation in Macrophages

Maydis Stigma (MS) is an herb traditionally used in many parts of the world. Previous studies have reported that MS plays a role in several biological activities, including antidiabetic and anticancer activities. However, the effects of a MS ethanolic extract (MSE) on the anti-inflammatory cellular mechanism remain unclear. Here, we investigated the anti-inflammatory properties of MSE and its molecular mechanism both in vitro and in vivo. The effects of MSE on the production of inflammatory mediators, cytokines, and related proteins and the identification of target genes were determined using LPS-stimulated macrophages. We also determined the analgesic and anti-inflammatory effects of MSE by examining acetic acid-induced writhing responses and xylene-induced ear edema in mice. Our results indicated that MSE markedly decreased iNOS and COX-2 levels without causing cytotoxicity and suppressed the secretion of NO in LPS-stimulated macrophages. MSE also inhibited the production of proinflammatory cytokines, such as TNF-[Formula: see text], IL-6, and IL-1[Formula: see text], and induced the expression of HO-1. Moreover, MSE treatment significantly reduced the LPS-stimulated activation of MAPK, NF-[Formula: see text]B, and AP-1. Furthermore, MSE exerted an analgesic effect on the acetic acid-induced abdominal writhing response test and an anti-inflammatory effect on xylene-induced ear edema in ICR mice. Finally, we investigated the components of MSE using UPLC-ESI-MS and found that it contains the maysin as a marker component. Overall, these observations demonstrate that MSE has anti-inflammatory and antinociceptive effects both in vitro and in vivo, which may provide new scientific evidence for its use as a potential therapeutic agent for the treatment of inflammation.

Anti-Inflammatory Effect of Rhapontici Radix Ethanol Extract via Inhibition of NF-κB and MAPK and Induction of HO-1 in Macrophages

Rhapontici Radix (RR) has been used in traditional medicine in East Asia and has been shown to have various beneficial effects. However, its biological properties or mechanism on inflammation-related diseases is unknown. The goal of this study was to determine the anti-inflammatory activity and underlying molecular mechanisms of Rhapontici Radix ethanol extract (RRE). The inhibitory effect of RRE on the production of NO, cytokines, inflammatory-related proteins, and mRNAs in LPS-stimulated macrophages was determined by the Griess assay, ELISA, Western blot analysis, and real-time RT-PCR, respectively. Our results indicate that treatment with RRE significantly inhibited the secretion of NO and inflammatory cytokines in RAW 264.7 cells and mouse peritoneal macrophages without cytotoxicity. We also found that RRE strongly suppressed the expression of iNOS and COX-2 and induced HO-1 expression. It also prevented nuclear translocation of NF-κB by inhibiting the phosphorylation and degradation of IκBα. Furthermore, the phosphorylation of MAPKs in LPS-stimulated RAW 264.7 cells was significantly inhibited by RRE. These findings suggest that RRE may operate as an effective anti-inflammatory agent by inhibiting the activation of NF-κB and MAPK signaling pathways and inducing HO-1 expression in macrophages. Our results suggest that RRE has potential value as candidate to inflammatory therapeutic phytomedicine.

Anti-Inflammatory Effects of Melandrii Herba Ethanol Extract via Inhibition of NF-κB and MAPK Signaling Pathways and Induction of HO-1 in RAW 264.7 Cells and Mouse Primary Macrophages

Melandrii Herba (MH) is a traditional Asian medicinal herb used to treat breast cancer, anuria, and diseases of lactation. However, its biological properties and molecular mechanisms have not been fully elucidated. The purpose of this study was to investigate the anti-inflammatory activity and underlying molecular mechanism of MH ethanol extract (MHE) on the lipopolysaccharide (LPS)-mediated inflammatory response in macrophages. MHE cytotoxicity was determined using a cell counting kit (CCK) assay. The effects of MHE on the production of NO, inflammatory cytokines, and related proteins and mRNAs were determined using the Griess test, ELISA, Western blotting, and real-time RT-PCR, respectively. In addition, intracellular signaling pathways, such as NF-κB, MAPK, and HO-1, were analyzed using Western blotting. Our results revealed that MHE treatment significantly inhibited the secretion of NO and inflammatory cytokines, including TNF-α, IL-6, and IL-1β in macrophages, at sub-cytotoxic concentrations. Furthermore, MHE treatment inhibited iNOS expression and induced HO-1 expression. Finally, the transcriptional activities of NF-κB and MAPK activation were significantly suppressed by MHE in LPS-stimulated macrophages. The results indicate that MHE exerts anti-inflammatory effects by suppressing inflammatory mediator production via NF-κB and MAPK signaling pathways inhibition and induction of HO-1 expression in macrophages. Therefore, our results suggest the potential value of MHE as an inflammatory therapeutic agent developed from a natural substance.

Anti-inflammatory effects of Viola yedoensis and the application of cell extraction methods for investigating bioactive constituents in macrophages

BACKGROUND

Viola yedoensis (VY, Violaceae) is a popular medicinal herb used in traditional eastern medicine for treating lots of diseases, including inflammation and its related symptoms. However, the anti-inflammatory properties of VY have not been demonstrated. In the present study, we investigated the anti-inflammatory effects of VY ethanol extract (VYE) on macrophages and attempted to identify the bioactive components of VYE.

METHODS

We assessed the effects of VYE on secretion of nitric oxide (NO) and inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. In addition, we explored the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and changes in heme oxygenase (HO)-1, nuclear factor (NF)-kB, and mitogen-activated protein kinase (MAPK) signaling pathways in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). In addition, a rapid and useful approach to identify potential bioactive components in VYE with anti-inflammatory effects was developed using murine macrophage cell extraction coupled with high-performance liquid chromatography tandem mass spectrometry (LC-MS).

RESULTS

We found that VYE exerted anti-inflammatory activity by inhibiting the production of key inflammation mediators and related products, as well as suppression of HO-1, NF-kB, and MAPK signaling pathway activation in RAW 264.7 cells. In addition, we identified two compounds in VYE via the cell extraction method.

CONCLUSIONS

Our results revealed that VYE exerts anti-inflammatory activities and its detailed inhibitory mechanism in macrophages. Furthermore, we identified bioactive components of VYE.

WMJ-S-001, a novel aliphatic hydroxamate derivative, exhibits anti-inflammatory properties via MKP-1 in LPS-stimulated RAW264.7 macrophages

BACKGROUND AND PURPOSE

Hydroxamate derivatives have attracted considerable attention because of their broad pharmacological properties. Recent studies reported their potential use in the treatment of cardiovascular diseases, arthritis and infectious diseases. However, the mechanisms of the anti-inflammatory effects of hydroxamate derivatives remain to be elucidated. In an effort to develop a novel pharmacological agent that could suppress abnormally activated macrophages, we investigated a novel aliphatic hydroxamate derivative, WMJ-S-001, and explored its anti-inflammatory mechanisms.

EXPERIMENTAL APPROACH

RAW264.7 macrophages were exposed to LPS in the absence or presence of WMJ-S-001. COX-2 expression and signalling molecules activated by LPS were assessed.

KEY RESULTS

LPS-induced COX-2 expression was suppressed by WMJ-S-001. WMJ-S-001 inhibited p38MAPK, NF-κB subunit p65 and CCAAT/enhancer-binding protein (C/EBP)β phosphorylation in cells exposed to LPS. Treatment of cells with a p38MAPK inhibitor (p38MAPK inhibitor III) markedly inhibited LPS-induced p65 and C/EBPβ phosphorylation and COX-2 expression. LPS-increased p65 and C/EBPβ binding to the COX-2 promoter region was suppressed in the presence of WMJ-S-001. In addition, WMJ-S-001 suppression of p38MAPK, p65 and C/EBPβ phosphorylation, and subsequent COX-2 expression were restored in cells transfected with a dominant-negative (DN) mutant of MAPK phosphatase-1 (MKP-1). WMJ-S-001 also caused an increase in MKP-1 activity in RAW264.7 macrophages.

CONCLUSIONS AND IMPLICATIONS

WMJ-S-001 may activate MKP-1, which then dephosphorylates p38MAPK, resulting in a decrease in p65 and C/EBPβ binding to the COX-2 promoter region and COX-2 down-regulation in LPS-stimulated RAW264.7 macrophages. The present study suggests that WMJ-S-001 may be a potential drug candidate for alleviating LPS-associated inflammatory diseases.

Design, synthesis, and evaluation of semi-conservative mono-carbonyl analogs of curcumin as anti-inflammatory agents against lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI), one of a few severe diseases with high mortality, cannot be tackled by any effective therapies so far.

Regulation of ubiquitin-specific processing protease 8 suppresses neuroinflammation

In our previous study, we reported that luteolin might exert neuroprotective functions by inhibiting the production of proinflammatory mediators, thereby suppressing microglial activation. In this study, we used two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to study the effect of ubiquitin-specific processing protease 8 (USP8) in luteolin-treated microglia. Western blot analysis verified that USP8 expression is upregulated by luteolin. Researchers have found that USP8 markedly enhanced the stability of neuregulin receptor degradation protein-1 (Nrdp1), which in turn inhibited the production of proinflammatory cytokines in toll-like receptor-triggered macrophages. We next hypothesized that luteolin inhibits microglial inflammation by regulating USP8 gene expression. After transfecting BV2-immortalized murine microglial cells with USP8, a significant reduction in the degradation of Nrdp1 was observed. USP8 overexpression also reduced the production of lipopolysaccharide (LPS)-induced proinflammatory mediators such as inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PGE2). We also found that USP8 siRNA blocked luteolin inhibition of pro-inflammatory gene expression such as iNOS, NO, COX-2, and PGE2. Taken together, our findings suggested that luteolin inhibits microglial inflammation by enhancing USP8 protein production. We concluded that in addition to anti-inflammatory luteolin, USP8 might represent a novel mechanism for the treatment of neuroinflammation and neurodegeneration.

Eliminating the heart from the curcumin molecule: monocarbonyl curcumin mimics (MACs)

Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs). A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK) profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria.

Jeju seaweeds suppress lipopolysaccharide-stimulated proinflammatory response in RAW 264.7 murine macrophages

OBJECTIVE

To investigate the anti-inflammatory effects of Jeju seaweeds on macrophage RAW 264.7 cells under lipopolysaccharide (LPS) stimulation.

METHODS

Ethyl acetate fractions were prepared from five different types of Jeju seaweeds, Dictyopteris divaricata (D. divaricata), Dictyopteris prolifera (D. prolifera), Prionitis cornea (P. cornea), Grateloupia lanceolata (G. lanceolata), and Grateloupia filicina (G. filicina). They were screened for inhibitory effects on proinflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6).

RESULTS

Our results revealed that D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina potently inhibited LPS-stimulated NO production (IC50 values were 18.0, 38.36, 38.43, 32.81 and 37.14 µg/mL, respectively). Consistent with these findings, D. divaricata, D. prolifera, P. cornea, and G. filicina also reduced the LPS-induced and prostaglandin E2 production in a concentration-dependent manner. Expectedly, they suppressed the expression of inducible NO synthase and cyclooxygenase-2 at the protein level in a dose-dependent manner in the RAW 264.7 cells, as determined by western blotting. In addition, the levels of TNF-α and IL-6, released into the medium, were also reduced by D. divaricata, D. prolifera, P. cornea, G. lanceolata, and G. filicina in a dose-dependent manner (IC50 values for TNF-α were 16.11, 28.21, 84.27, 45.52 and 74.75 µg/mL, respectively; IC50 values for IL-6 were 37.35, 80.08, 103.28, 62.53 and 84.28 µg/mL, respectively). The total phlorotannin content was measured by the Folin-Ciocalteu method and expressed as phloroglucinol equivalents. The content was 92.0 µg/mg for D. divaricata, 151.8 µg/mg for D. prolifera, 57.2 µg/mg for P. cornea, 53.0 µg/mg for G. lanceolata, and 40.2 µg/mg for G. filicina.

CONCLUSIONS

Thus, these findings suggest that Jeju seaweed extracts have potential therapeutic applications for inflammatory responses.

Investigations into the role of 26S proteasome non-ATPase regulatory subunit 13 in neuroinflammation

OBJECTIVE

To investigate 26S proteasome non-ATPase regulatory subunit 13 (PSMD13) gene silencing as a potential treatment for neuroinflammatory disorders via regulation of microglial activation and production of inflammatory mediators.

METHODS

RNA interference was used to knockdown PSMD13 gene expression, followed by inhibitors of κB (IκBα) protein degradation and nuclear factor κB (NF-κB) activity measurement in lipopolysaccharide (LPS)-stimulated BV2 microglia. Nitrite (Griess) assay, reporter gene assay, enzyme-linked immunosorbent assay and Western blot were used to investigate the role of PSMD13 in microglial activation and inflammation.

RESULTS

PSMD13 gene knockdown significantly reduced IκBα degradation and NF-κB activation in LPS-stimulated murine BV2 microglia. It also decreased the production of LPS-induced proinflammatory mediators, such as inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and prostaglandin E2.

CONCLUSIONS

PSMD13 gene silencing suppressed the production of proinflammatory mediators by modulating ubiquitin-proteasome system-mediated neuroinflammation via the downregulation of IκBα degradation and NF-κB activation in LPS-stimulated BV2 microglia. PSMD13 gene knockdown may have therapeutic implications for the treatment of neuroinflammatory disorders.

Cause of idiopathic sudden sensorineural hearing loss: The stress response theory

The stress response theory is a relatively new concept about the cause of idiopathic sudden sensorineural hearing loss (ISHL). A number of possible etiologies have been proposed in the literature, as discussed in this paper, but each proposed etiology has been both supported and refuted in the literature. However, the stress response theory can integrate hypotheses that have been advocated so far. The word “stress” refers to a constellation of physical and psychological stimuli including systemic viral and bacterial illness, systemic inflammatory disorders, and physical, mental or metabolic stress. Numerous studies have demonstrated adverse effects of systemic stress on health. Stress causes changes in the immune system and cytokine network through activation of the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system. Several types of catecholamine and cytokine receptors are in the cochlea cells other than capillary cells, and then they can respond to systemic stressors. However, there are few studies examining how systemic stress is associated with cochlear dysfunction. The stress response theory addresses this question. In the theory, a variety of stressors and risk factors contribute to the onset of ISHL in varying degrees. The lateral wall of the cochlea has very unique responses to systemic stressors. It plays a critical role in causing ISHL. Systemic stressors converge at the lateral wall and trigger pathological activation of nuclear factor κ-light-chain-enhancer of activated B cells, a transcriptional factor known as a stress sensor. This activation enhances local expression of genes associated with immune and inflammatory system, resulting in cochlear dysfunction. We review the original stress response theory advocated by Adams et al and the integrative stress response theory that integrates our knowledge about the etiologies of ISHL so far.

Peimine impairs pro-inflammatory cytokine secretion through the inhibition of the activation of NF-κB and MAPK in LPS-induced RAW264.7 macrophages

In the previous study, we found that peimine has good anti-inflammatory effects in vivo. However, the anti-inflammatory mechanism of peimine remains unclear. We, therefore, assessed the effects of peimine on inflammatory cytokines in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that peimine (0-25 mg/L) significantly inhibited tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and increased IL-10 production. Furthermore, peimine significantly inhibited the phosphorylation of p38, ERK and c-jun N-terminal kinase (JNK) as well as decreased p65 and IκB. The present results indicate that peimine inhibits the production of inflammatory cytokines induced by LPS through blocking MAPKs and NF-κB signaling pathways.

Saikosaponin A mediates the inflammatory response by inhibiting the MAPK and NF-κB pathways in LPS-stimulated RAW 264.7 cells

Saikosaponin A (SSA) is a major triterpenoid saponin isolated from Radix bupleuri (RB), a widely used Chinese traditional medicine to treat various inflammation-related diseases. The aim of this study was to investigate the anti-inflammatory activity, as well as the molecular mechanism of SSA in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. In this study, we demonstrated that SSA markedly inhibits the expression of certain immune-related cytotoxic factors, including cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS), as well as pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. It also significantly upregulates the expression of IL-10, an important anti-inflammatory cytokine, suggesting its anti-inflammatory activity in LPS-stimulated macrophages. We further demonstrated that SSA inhibits the activation of the nuclear factor-κB (NF-κB) signaling pathway by suppressing the phosphorylation of inhibitory NF-κB inhibitor α (IκBα) and thus holding p65 NF-κB in the cytoplasm to prevent its translocation to the nucleus. In addition, SSA also inhibits the mitogen-activated protein kinase (MAPK) signaling pathway by downregulating the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK), the three key components of the MAPK family. In conclusion, our study demonstrates that SSA has an anti-inflammatory effect by regulating inflammatory mediators and suppressing the MAPK and NF-κB signaling pathways in LPS-stimulated RAW 264.7 cells.

Inhibition of 26S protease regulatory subunit 7 (MSS1) suppresses neuroinflammation

Recently, researchers have focused on immunosuppression induced by rifampicin. Our previous investigation found that rifampicin was neuroprotective by inhibiting the production of pro-inflammatory mediators, thereby suppressing microglial activation. In this study, using 2-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS), we discovered that 26S protease regulatory subunit 7 (MSS1) was decreased in rifampicin-treated microglia. Western blot analysis verified the downregulation of MSS1 expression by rifampicin. As it is indicated that the modulation of the ubiquitin-26S proteasome system (UPS) with proteasome inhibitors is efficacious for the treatment of neuro-inflammatory disorders, we next hypothesized that silencing MSS1 gene expression might inhibit microglial inflammation. Using RNA interference (RNAi), we showed significant reduction of IkBα degradation and NF-kB activation. The production of lipopolysaccharides-induced pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), nitric oxide, cyclooxygenase-2, and prostaglandin E₂ were also reduced by MSS1 gene knockdown. Taken together, our findings suggested that rifampicin inhibited microglial inflammation by suppressing MSS1 protein production. Silencing MSS1 gene expression decreased neuroinflammation. We concluded that MSS1 inhibition, in addition to anti-inflammatory rifampicin, might represent a novel mechanism for the treatment of neuroinflammatory disorders.