A novel synthetic derivative of melatonin, 5-hydroxy-2'-isobutyl-streptochlorin (HIS), inhibits inflammatory responses via regulation of TRIF-dependent signaling and inflammasome activation.

Melatonin is substantially reported to possess anti-inflammatory properties. In the present study, we synthesized a novel melatonin derivative, 5-hydroxy-2'-isobutyl-streptochlorin (HIS), which displayed superior anti-inflammatory properties to its parent compound. Further, we explored its underlying mechanisms in cellular and experimental animal models. Lipopolysaccharide was used to induce in vitro inflammatory responses in RAW 264.7 macrophages. LPS-primed macrophages were pulsed with biologically unrelated toxic molecules to evaluate the role of HIS on inflammasome activation. In vivo verifications were carried out using acute lung injury (ALI) and Escherichia coli-induced septic shock mouse models. HIS inhibited the production of proinflammatory mediators and cytokines such as nitric oxide, cyclooxygenase 2, IL-1ß, IL-6 and TNF-α in LPS-stimulated RAW 264.7 macrophages. HIS suppressed the infiltration of immune cells into the lung and the production of pro-inflammatory cytokines such as IL-6 and TNF-α in broncho-alveolar lavage fluid in the ALI mouse model. Mechanistic studies revealed that the inhibitory effects of HIS were mediated through the regulation of the TIR domain-containing, adaptor-inducing, interferon-ß (TRIF)-dependent signaling pathway from toll-like receptors. Further, HIS attenuated IL-1ß secretion via the inhibition of NLRP3 inflammasome activation independent of mitochondrial ROS production. Furthermore, HIS suppressed IL-1ß, IL-6 and interferon-ß production in peritoneal lavage in the Escherichia coli-induced sepsis mouse model. In conclusion, HIS exerted potent anti-inflammatory effects via the regulation of TRIF-dependent signaling and inflammasome activation. Notably, the superior anti-inflammatory properties of this derivative compared with its parent compound could be a promising lead for treating various inflammatory-mediated diseases.

Eucalyptus globulus Inhibits Inflammasome-Activated Pro-Inflammatory Responses and Ameliorate Monosodium Urate-Induced Peritonitis in Murine Experimental Model.

Eucalyptus globulus Labill. (E. globulus, Myrtaceae) is used in Europe as a traditional folk remedy for inflammation-related disorders such as arthritis, diabetes, asthma, and gout. We investigated this study to evaluate the protective effects of E. globulus extract (EG) on inflammatory responses, and provide scientific and mechanistic evidence in in vitro and in vivo experimental models. LPS-stimulated murine bone marrow-derived macrophages (BMDMs) were used to study the regulatory effect of EG on inflammasome activation in vitro. Monosodium urate (MSU)-induced peritonitis was used to study the effect of EG in an in vivo murine model. EG suppressed IL-[Formula: see text] secretion via the regulation of apoptosis-associated speck-like proteins containing a CARD (ASC) oligomerization and caspase-1 maturation, leading to the inhibition of inflammasome activation. In the in vivo study, EG suppressed the MSU-induced peritonitis by attenuating interleukin (IL)-1[Formula: see text], providing scientific support for its traditional use in the treatment of inflammation-related disorders.

Cichorium intybus Linn. Extract Prevents Type 2 Diabetes Through Inhibition of NLRP3 Inflammasome Activation.

This study provides the scientific basis for the inhibitory effect of the aerial parts of Cichorium intybus Linn. (C. intybus) on the activation of the NLRP3 inflammasome in vitro and on high-fat diet (HFD)-induced type-2 diabetes (T2D). Lipopolysaccharide (LPS)-primed bone marrow-derived macrophages were used to study the effects methanolic extract of C. intybus leaf (CI) on inflammasome activation. An insulin resistance model (mice fed a HFD) was used to study the in vivo effect of CI on T2D. CI attenuated interleukin-1ß (IL-1ß) secretion by inhibiting the activation of the NLRP3 inflammasome in mouse bone marrow macrophages. The CI treatment attenuated the intracellular movement of NLRP3 in Triton X-100 insoluble fraction, without affecting the expression of other NLRP3 inflammasome-related proteins. Attenuated IL-1ß secretion may improve glucose metabolism in the HFD-fed insulin resistance mouse model. CI also attenuated the infiltration of M1 macrophages and increased the M2 macrophage population in white adipose tissue. Collectively, our data showed that CI inhibits IL-1ß secretion through attenuation of NLRP3 inflammasome activation, leading to an antidiabetic effect by improving glucose metabolism and inhibiting metainflammation.

Emodin attenuates A23187-induced mast cell degranulation and tumor necrosis factor-α secretion through protein kinase C and IκB kinase 2 signaling.

Mast cells are known to play a pivotal role in allergic diseases. Cross-linking of the high-affinity IgE receptor (FcεRI) is known to be one of the major causes that lead to degranulation and allergic inflammation. An increase in intracellular calcium (Ca(2+)) concentration also triggers degranulation, bypassing receptor activation. Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is known to exhibit a variety of pharmacological activities including anti-allergic effects. However, the detailed molecular mechanisms involved in exhibiting anti-allergic effects by emodin were remained to be clarified. In the present investigation we report the regulatory function of emodin on the allergic signal mediators through Ca(2+) ionophore activation in mast cells. Emodin significantly inhibited A23187-induced tumor necrosis factor-α production and degranulation through the attenuation of protein kinase C, IκB kinase 2, and soluble N-ethylmaleimide-sensitive fusion factor attachment protein receptor complex formation, bypassing FcεRI activation. Data from our study indicated that emodin acts by regulating multiple signaling pathways in inhibiting the allergic reactions in mast cells.