SM905, an artemisinin derivative, inhibited NO and pro-inflammatory cytokine production by suppressing MAPK and NF-kappaB pathways in RAW 264.7 macrophages

Suppression of IP-10/CXCL10 gene expression in LPS- and/or IFN-γ-stimulated macrophages by parasite-secreted products

T helper (Th)2 polarized immune responses are characteristically dominant in helminth infections. The gene expression of interferon (IFN)-γ-inducible protein 10 (IP-10/CXCL10), which promotes Th1 responses, in mouse macrophages stimulated with lipopolysaccharide (LPS) and/or IFN-γ was suppressed by excretory/secretory (ES) products of Spirometra erinaceieuropaei plerocercoids. ES products suppressed LPS- and/or IFN-γ-induced transcriptional activities of a luciferase reporter gene under the control of a 243-bp fragment of the IP-10 gene promoter/enhancer, which contains an IFN-stimulated response element (ISRE) and two κB elements. Consistent with this result, ES products inhibited ISRE-dependent heterologous promoter activities and LPS- or IFN-γ-induced ISRE-binding activity. ES products also suppressed LPS-induced IFN-β gene expression. Furthermore, ES products suppressed nuclear factor (NF)-κB RelA (p65)-dependent transcriptional activity, whereas ES products had no effect on the κB-binding activity. These results suggest that ES products suppress the IP-10 gene expression by inhibiting the ISRE- and RelA-dependent transcriptional activities in mouse macrophages.

Artemisinin attenuates lipopolysaccharide-stimulated proinflammatory responses by inhibiting NF-κB pathway in microglia cells

Microglial activation plays an important role in neuroinflammation, which contributes to neuronal damage, and inhibition of microglial activation may have therapeutic benefits that could alleviate the progression of neurodegeneration. Recent studies have indicated that the antimalarial agent artemisinin has the ability to inhibit NF-κB activation. In this study, the inhibitory effects of artemisinin on the production of proinflammatory mediators were investigated in lipopolysaccharide (LPS)-stimulated primary microglia. Our results show that artemisinin significantly inhibited LPS-induced production of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1) and nitric oxide (NO). Artemisinin significantly decreased both the mRNA and the protein levels of these pro-inflammatory cytokines and inducible nitric oxide synthase (iNOS) and increased the protein levels of IκB-α, which forms a cytoplasmic inactive complex with the p65-p50 heterodimeric complex. Artemisinin treatment significantly inhibited basal and LPS-induced migration of BV-2 microglia. Electrophoretic mobility shift assays revealed increased NF-κB binding activity in LPS-stimulated primary microglia, and this increase could be prevented by artemisinin. The inhibitory effects of artemisinin on LPS-stimulated microglia were blocked after IκB-α was silenced with IκB-α siRNA. Our results suggest that artemisinin is able to inhibit neuroinflammation by interfering with NF-κB signaling. The data provide direct evidence of the potential application of artemisinin for the treatment of neuroinflammatory diseases.

Anti-inflammatory and anti-allergic effects of Agrimonia pilosa Ledeb extract on murine cell lines and OVA-induced airway inflammation

ETHNOPHARMACOLOGICAL EVIDENCE

Agrimonia pilosa Ledeb (Rosaceae, AP) has long been used as a traditional medicine in Korea and other Asian countries to treat various diseases.

AIM OF THE STUDY

In the present study, the anti-inflammatory and anti-allergic effects of AP extract in in vitro cell lines and in vivo mouse model of inflammation and the molecular mechanisms involved were reported.

MATERIALS AND METHODS

Using Raw 264.7 murine macrophages the effects of methanol extract of AP in lipopolysaccharide (LPS)-induced production of inflammatory mediators were measured. Further IgE-DNP-induced interleukin (IL)-4 production and degranulation in RBL-2H3 rat basophilic cell lines was also estimated. To investigate the anti-asthmatic effect of AP in vivo, airway inflammation in ovalbumin (OVA)-induced mouse model was used.

RESULTS

AP attenuated the production of inflammatory mediators such as NO, PGE(2) and pro-inflammatory cytokines in LPS-induced Raw 264.7 cells. Further, AP inhibited IL-4 production and degranulation in IgE-DNP-induced RBL-2H3 cells. Furthermore, AP attenuated the infiltration of immune cells into lung, cytokines production in broncho-alveolar lavage fluid (BALF) and airway-hyperresponsiveness (AHR) on OVA-induced mouse model of inflammation.

CONCLUSION

Our results showed that AP attenuated the activation of macrophages, basophils, and inhibited the OVA-induced airway inflammation. The molecular mechanisms leading to AP's potent anti-inflammatory and anti-allergic effects might be through regulation of TRIF-dependent and Syk-PLCγ/AKT signaling pathways, suggesting that AP may provide a valuable therapeutic strategy in treating various inflammatory diseases including asthma.

TNFα and IL-1β are mediated by both TLR4 and Nod1 pathways in the cultured HAPI cells stimulated by LPS

A growing body of evidence recently suggests that glial cell activation plays an important role in several neurodegenerative diseases and neuropathic pain. Microglia in the central nervous system express toll-like receptor 4 (TLR4) that is traditionally accepted as the primary receptor of lipopolysaccharide (LPS). LPS activates TLR4 signaling pathways to induce the production of proinflammatory molecules. In the present studies, we verified the LPS signaling pathways using cultured highly aggressively proliferating immortalized (HAPI) microglial cells. We found that HAPI cells treated with LPS upregulated the expression of TLR4, phospho-JNK (pJNK) and phospho-NF-κB (pNF-κB), TNFα and IL-1β. Silencing TLR4 with siRNA reduced the expression of pJNK, TNFα and IL-1β, but not pNF-κB in the cells. Inhibition of JNK with SP600125 (a JNK inhibitor) decreased the expression of TNFα and IL-1β. Unexpectedly, we found that inhibition of Nod1 with ML130 significantly reduced the expression of pNF-κB. Inhibition of NF-κB also reduced the expression of TNFα and IL-1β. Nod1 ligand, DAP induced the upregulation of pNF-κB which was blocked by Nod1 inhibitor. These data indicate that LPS-induced pJNK is TLR4-dependent, and that pNF-κB is Nod1-dependent in HAPI cells treated with LPS. Either TLR4-JNK or Nod1-NF-κB pathways is involved in the expression of TNFα and IL-1β.

SM934 treated lupus-prone NZB × NZW F1 mice by enhancing macrophage interleukin-10 production and suppressing pathogenic T cell development

Background

Artemisinin and its derivatives were reported to possess strong regulatory effects on inflammation and autoimmune diseases. This study was designed to examine the therapeutic effects and underlying mechanisms of SM934, a water-soluble artemisinin analogue, on lupus-prone female NZB×NZW F₁ mice.

Methodology/Principal Findings

NZB/W F₁ mice were treated orally with SM934 for 3 or 6 months respectively to investigate the effect on clinical manifestations and immunological correlates. To further explore the mechanisms of SM934, ovalbumin (OVA)-immunized or interferon (IFN)-γ-elicited C57BL/6 mice were used. In vivo, treatment with SM934 for 3 or 6 months significantly delayed the progression of glomerulonephritis and increased the survival rate of NZB/W F₁ mice. Clinical improvement was accompanied with decreased Th1-related anti-double-strand DNA (dsDNA) IgG2a and IgG3 Abs, serum interleukin (IL)-17, and increased Th2-related anti-dsDNA IgG1 Ab, serum IL-10 and IL-4. SM934 treatment also suppressed the accumulation of effector/memory T cells, induced the apoptosis of CD4⁺ T cells, while enhancing the development of regulatory T cells in NZB/W F₁ mice. In addition, SM934 treatment promoted the IL-10 production of macrophages from NZB/W F₁ mice, OVA-immunized C57BL/6 mice and IFN-γ-elicited C57BL/6 mice. In vitro, SM934 enhanced IL-10 production from primary macrophages stimulated with IFN-γ.

Conclusions/Significance

The results of this study demonstrated that artemisinin analogue SM934 had therapeutic effects on lupus-prone female NZB/W F₁ mice by inhibiting the pathogenic helper T cell development and enhancing anti-inflammatory cytokine IL-10 production.

Oral administration of artemisinin analog SM934 ameliorates lupus syndromes in MRL/lpr mice by inhibiting Th1 and Th17 cell responses

OBJECTIVE

SM934, an artemisinin derivative, possesses potent antiproliferative and antiinflammatory properties. The aim of this study was to examine the effects and explore the mechanisms of SM934 to treat autoimmune disease in lupus-prone female MRL/lpr mice.

METHODS

In vitro, the effects of SM934 on the activation of polyclonal CD4+ T cells and the differentiation of naive CD4+ T cells were examined. In vivo, the preventative or therapeutic effects of SM934 in MRL/lpr mice were investigated. Ex vivo, the mechanisms of treatment were explored according to the immunologic correlates of disease.

RESULTS

In vitro, SM934 inhibited interferon-γ (IFNγ) and interleukin-17 (IL-17) production from polyclonal CD4+ T cells activated by T cell receptor engagement and the differentiation of naive CD4+ T cells into Th1 and Th17 cells, but not Treg cells. In vivo, 12-week-old MRL/lpr mice treated with SM934 for 4 weeks showed significantly ameliorated proteinuria and renal lesion severity; decreased levels of blood urea nitrogen, serum IFNγ, and serum anti-double-stranded DNA antibodies; decreased spleen size; and a lower percentage of CD3+B220+CD4-CD8- T cells; 16-week-old MRL/lpr mice treated with SM934 for 8 weeks avoided severe proteinuria and survived longer. Ex vivo, SM934 treatment elevated the percentage of Treg cells, inhibited the development of Th1 and Th17 cells, and impeded the comprehensive activation of STAT-1, STAT-3, and STAT-5 proteins in splenocytes.

CONCLUSION

Taken together, the results of this study demonstrated that the artemisinin analog SM934 had therapeutic effects in lupus-prone female MRL/lpr mice by inhibiting both Th1 cell and Th17 cell responses. Moreover, this study indicated that both IFNγ and IL-17 are required for the elicitation and development of murine lupus.

Artemisinins and immune system

Artemisinins in combination with other antimalarial drugs remain the mainstay of current antimalarial armamentarium. It is interesting to note that many traditional drugs with antiprotozoal background can wield immunomodulation on the recipient's immune system in a positive or negative direction. Artemisinins also attribute immunomodulatory distensions. For instance, they demonstrate predominant immunosuppressive traits toward different immune components by particularly regulating the cellular proliferation and cytokine release, which indicates that they possess some additional mechanisms and features demanding deliberate attentions. This article reviews the data-based immunomodulatory effects of artemisinins on different immune cells including neutrophils, macrophages, splenocytes, T and B cells in conjunction with their therapeutic prospective with regard to inflammation, autoimmunity and delayed-type hypersensitivity.

Methyl-1-hydroxy-2-naphthoate, a novel naphthol derivative, inhibits lipopolysaccharide-induced inflammatory response in macrophages via suppression of NF-κB, JNK and p38 MAPK pathways

OBJECTIVE AND DESIGN

The anti-inflammatory effect of methyl-1-hydroxy-2-naphthoate (MHNA), a novel naphthol derivative, was evaluated in the lipopolysaccharide (LPS)-induced inflammatory response in murine macrophages.

MATERIALS AND METHODS

The release of nitric oxide (NO), interleukin-1beta (IL-1β) and interleukin-6 (IL-6) were detected by the Griess reagent and ELISA methods. The protein expressions of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) were examined by Western blotting. The mRNA expressions of IL-1β, IL-6, iNOS and COX-2 were determined by real-time PCR. Activation of mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) pathways were detected by Western blotting, reporter gene assay and electrophoretic mobility shift assay.

RESULTS

MHNA significantly inhibited the release of NO, IL-1β and IL-6 as well as the protein expression of iNOS and COX-2 in LPS-stimulated macrophages. It also inhibited the mRNA expression of iNOS, COX-2, IL-1β and IL-6. Further studies indicated that MHNA inhibited LPS-induced increases in NF-κB DNA-binding activity and NF-κB transcriptional activity as well as IκB-α degradation and NF-κB translocation in a dose-dependent manner. Meanwhile, the activation of p38 MAPK and c-Jun N-terminal kinases (JNK) induced by LPS were decreased by MHNA.

CONCLUSIONS

MHNA inhibits the LPS-induced inflammatory response in murine macrophages via suppression of NF-κB and MAPKs signaling pathways activation.

Heme synthesis increases artemisinin-induced radical formation and cytotoxicity that can be suppressed by superoxide scavengers

Artemisinin (ART) is a sesquiterpene lactone natural product that is widely used to treat multi-drug resistant strains of malaria. Artemisinin and its derivatives are also selectively cytotoxic to cancer cells, which can be modulated by altering heme synthesis. Cytotoxicity to cancer cells is thought to involve generation of oxidative stress, although conflicting data exist. We have analyzed reactive oxygen species (ROS) generation using the fluorescent probes 2',7'-dichlorodihydrofluorescein diacetate (DCF) and dihydroethidine (HET) upon exposure to dihydroartemisinin (DHA) in Molt-4 leukemia cells. HET fluorescence correlated with dose-dependent DHA-induced cytotoxicity, increased within 30 min of DHA exposure, and was significantly enhanced by increasing heme synthesis. Protein levels of copper, zinc-superoxide dismutase (CuZnSOD), manganese-superoxide dismutase (MnSOD), catalase, and glutathione peroxidases 1/2 were also found to increase with DHA exposure. 4-hydroxy-tempol (TEMPOL) and DF-Mn, MnSOD mimetics, could significantly inhibit ROS generation and reduce cell death. Production of superoxide appears to be a central mediator of cytotoxicity from DHA.