1,8-Cineol inhibits nuclear translocation of NF-κB p65 and NF-κB-dependent transcriptional activity

Natural plant-derived products are commonly applied to treat a broad range of human diseases, including cancer as well as chronic and acute airway inflammation. In this regard, the monoterpene oxide 1,8-cineol, the active ingredient of the clinically approved drug Soledum®, is well-established for the therapy of airway diseases, such as chronic sinusitis and bronchitis, chronic obstructive pulmonary disease and bronchial asthma. Although clinical trials underline the beneficial effects of 1,8-cineol in treating inflammatory diseases, the molecular mode of action still remains unclear.Here, we demonstrate for the first time a 1,8-cineol-depending reduction of NF-κB-activity in human cell lines U373 and HeLa upon stimulation using lipopolysaccharides (LPS). Immunocytochemistry further revealed a reduced nuclear translocation of NF-κB p65, while qPCR and western blot analyses showed strongly attenuated expression of NF-κB target genes. Treatment with 1,8-cineol further led to increased protein levels of IκBα in an IKK-independent matter, while FRET-analyses showed restoring of LPS-associated loss of interaction between NF-κB p65 and IκBα. We likewise observed reduced amounts of phosphorylated c-Jun N-terminal kinase 1/2 protein in U373 cells after exposure to 1,8-cineol. In addition, 1,8-cineol led to decreased amount of nuclear NF-κB p65 and reduction of its target gene IκBα at protein level in human peripheral blood mononuclear cells.Our findings suggest a novel mode of action of 1,8-cineol through inhibition of nuclear NF-κB p65 translocation via IκBα resulting in decreased levels of proinflammatory NF-κB target genes and may therefore broaden the field of clinical application of this natural drug for treating inflammatory diseases.     

Synthesis and evaluation of the anti-proliferative and NF-κB activities of a library of simplified tylophorine analogs

Tylophorine and many related phenanthropiperidine alkaloids are extraordinarily potent anti-proliferative agents. Despite their impressive anti-cancer activity, clinical development of these alkaloids has been hampered by their poor solubility and neurological side effects. Although it has been suggested that developing polar phenanthropiperidines will mitigate these undesired properties, the lack of practical methods for the synthesis of such analogues has limited this effort. Here, we present a concise synthetic approach to N-substituted phenanthropiperidines, which enabled a systematic investigation of structure-activity relationships at an underexplored region of the tylophorine scaffold. This work suggests that ring E of tylophorine is essential for the anti-proliferative activity of the 6,7,10,11-tetramethoxy-1,2,3,4-tetrahydrodibenzo[f,h]isoquinoline core scaffold.     

Regulation of NF-κB-dependent gene expression by ligand-induced endocytosis of the interleukin-1 receptor

Interleukin-1 (IL-1) induces the internalization of its cognate receptor from the plasma membrane. However, it has remained elusive as to how this mechanism affects the IL-1-induced signal transduction. In this study, we used small-molecule inhibitors of receptor endocytosis to analyze the effects on IL-1-induced signal transduction pathways. We demonstrate that the inhibition of endocytosis down-modulates IL-1-induced NF-κB-dependent gene expression at a level downstream of nuclear translocation and DNA binding of NF-κB. Moreover, we report that the reduced NF-κB-dependent gene expression disrupts feedback inhibition loops terminating the activation of mitogen-activated protein kinases and down-regulating the expression of IL-1-induced mRNAs. Collectively, we show that the inhibition of endocytosis causes a dysregulation of IL-1-induced signal transduction and gene expression demonstrating an important role for receptor internalization in IL-1 signaling.     

Relationship between the octanol-water partition coefficient of tertiary amines and their effect of ‘selective’ uncoupling of photophosphorylation

A series of tertiary amines was investigated for effects on the transmembrane proton potential difference ( H), on photophosphorylation and on electron-flux control related to the intrathylakoid proton potential ( H_I), using isolated chloroplasts ofSpinacia oleracea L. As indicated by 9-aminoacridine fluorescence and [14C]methylamine uptake, all amines studied inhibited a build-up of H and, in parallel, ATP synthesis. Even when H was low, strong H₁-dependent electron-flux control was observed under the influence of tertiary amines. The strength of flux control in the presence of low H and the effectiveness of inhibition of ATP synthesis linearly increased with the lipophilicity of the amines. The most effective of the amines tested caused 50% inhibition of ATP synthesis at a concentration of 6 M, which is about 1000-fold lower than the concentration required for inhibition by methylamine. The data presented indicate the existence of two proton domains in the thylakoid vesicles, one of them feeding the ATP-synthase, the other the sites of pH-dependent electron-flux control. It is concluded that tertiary amines develop their action in a lipophilic domain of the thylakoid membrane, in the vicinity of the ATP-synthase complex. A mechanism for selective uncoupling and for the maintenance of H_I-dependent electron flux control in the presence of low H is discussed.Abbreviations and symbols coefficient for pH-dependent electron flux control - 9-AA 9-aminoacridine - Chl chlorophyll - I₅₀ amine concentration producing 50% inhibition of ATP-synthesis - J_e flux of photosynthetic electron transport - k _H apparent rate constant for proton efflux - H₁ proton potential in the thylakoid lumen - H₁ transthylakoid proton potential difference - p partition coefficient - q _AA coefficient for 9-aminoacridine fluorescence quenching - PS photosystem - Q quantum flux of photosynthetically active light Dedicated to Professor Wilhelm Simonis, on the occasion of his 80th birthday     

Antagonistic crosstalk between NF-κB and SIRT1 in the regulation of inflammation and metabolic disorders

Recent studies have indicated that the regulation of innate immunity and energy metabolism are connected together through an antagonistic crosstalk between NF-κB and SIRT1 signaling pathways. NF-κB signaling has a major role in innate immunity defense while SIRT1 regulates the oxidative respiration and cellular survival. However, NF-κB signaling can stimulate glycolytic energy flux during acute inflammation, whereas SIRT1 activation inhibits NF-κB signaling and enhances oxidative metabolism and the resolution of inflammation. SIRT1 inhibits NF-κB signaling directly by deacetylating the p65 subunit of NF-κB complex. SIRT1 stimulates oxidative energy production via the activation of AMPK, PPARα and PGC-1α and simultaneously, these factors inhibit NF-κB signaling and suppress inflammation. On the other hand, NF-κB signaling down-regulates SIRT1 activity through the expression of miR-34a, IFNγ, and reactive oxygen species. The inhibition of SIRT1 disrupts oxidative energy metabolism and stimulates the NF-κB-induced inflammatory responses present in many chronic metabolic and age-related diseases. We will examine the molecular mechanisms of the antagonistic signaling between NF-κB and SIRT1 and describe how this crosstalk controls inflammatory process and energy metabolism. In addition, we will discuss how disturbances in this signaling crosstalk induce the appearance of chronic inflammation in metabolic diseases.