A series of 1-(2-oxocyclohexyl)butane-1, 3-dione derivatives were designed and synthesized as TLR4 inhibitors by modifying the core structure of the lead compound ((6, 8-dioxo-1, 2, 3, 4, 6, 7, 8, 8a-octahydronaphthalen-2-yl) carbamate)). In vitro , compound 3p significantly inhibited the proliferation of rat synovial cells, inhibited the proliferation of LPS-induced RAW264.7 cells, and inhibited TLR4 activity, with IC 50 values of 1.21 ± 0.09 μM, 0.73 ± 0.05 μM and 0.43 ± 0.03 μM, respectively, which was superior to the positive control methotrexate. In vivo anti-rheumatoid arthritis evaluation, compound 3p can significantly inhibit the inflammatory factors TNF-α, IL-1β and IL-6, so as to achieve the therapeutic purpose. In the preliminary mechanism study, compound 3p has obvious regulatory effects on the abnormal increase of TLR4, JAK2 and STAT3 protein and gene expression related to inflammatory signaling pathway in RAW264.7 cells. In summary, this study aims to develop more effective candidates for rheumatoid arthritis.
Previous studies have detected microplastics (MPs) in human biological samples, such as lungs, alveolar lavage fluid, and thrombus. However, whether MPs induce health effects after inhalation are unclear. In this study, fluorescent polystyrene microplastics (PS-MPs) were found in the thymus, spleen, testes, liver, kidneys, and brain on day 1 or day 3 after one intratracheal instillation. Furthermore, mice showed inflammation in multiple organs, manifested as obvious infiltration of neutrophils and macrophages, increased Toll-like receptors (TLRs), myeloid differentiation primary response protein 88 (MyD88) and nuclear factor-κB (NF-κB), as well as proinflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-1β) in the lungs, thymus, spleen, liver, and kidneys after four intratracheal instillations of PS-MPs at once every 2 weeks. Hepatic and renal function indexes were also increased. Subsequently, the inflammatory response in multiple murine organs was significantly alleviated by TLR2 and TLR4 inhibitors. Unexpectedly, we did not find any elevated secretion of monocyte chemotactic protein (MCP)-1 or TNF-α by RAW264.7 macrophages in vitro. Thus, PS-MPs induced inflammatory injuries in multiple murine organs via the TLRs/MyD88/NF-κB pathway in vivo, but not macrophages in vitro. These results may provide theoretical support for healthy protection against PS-MPs and their environmental risk assessment.
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