Environmental pollutants are recognized as one of the major concerns for public health. The free‐living nematode Caenorhabditis elegans are widely used to evaluate the toxicity of environmental contaminants in biomonitoring researches. In the present study, a new transgenic strain, rps‐30−/−;RFP‐RPS‐30UbL was generated, with constitutively active rps‐30 promoter used to control the expression of RFP‐RPS‐30UbL fusion protein. We found RFP‐RPS‐30UbL would accumulate to form ‘rod‐like’ structures, when worms were exposed to environmental contaminants, including Cd, Hg, Pb, As, Paraquat and Dichlorvos. The number of the ‘rod‐like’ structures was induced by environmental contaminants in a concentration‐ and time‐dependent manner. The ‘rod‐like’ structure formation could be detectable in response to the concentration of each contaminant as low as 24‐h LC50 × 10−7, and the detectable time could be within 2 h. Detecting the transcription and expression levels of RFP‐RPS‐30UbL in worms exposed to different kinds of environmental contaminants showed that the expression level of RFP‐RPS‐30UbL was not regulated by environmental contaminants, and the number differences of ‘rod‐like’ structures were just due to the morphological change of RFP‐RPS‐30UbL from dispersion to accumulation induced by environmental contaminants. In addition, this transgenic strain was developed in rps‐30−/− homozygous worm, which was a longevity strain. Detection of lifespan and brood size showed that rps‐30−/−;RFP‐RPS‐30UbL transgenic worm was more suitable to be cultured and used further than N2;GFP‐RPS‐30UbL, for expressing RPS‐30UbL in wild type N2 worms shortened the lifespan and deceased the brood size. Therefore, rps‐30−/−;RFP‐RPS‐30UbL transgenic worm might play a potential role in versatile environmental biomonitoring, with the advantage of not only the convenient and quick fluorescence‐based reporter assay, but also the quantificational evaluation of the toxicities of environmental contaminants using ‘rod‐like’ structures with high sensitivity, off‐limited the expression level of the reporter protein.

Background Osteoarthritis (OA), a common chronic joint disease, is characterized by cartilage degeneration and subchondral bone reconstruction. Nuclear factor kappa-B (NF-κB) signaling pathway-activated inflammation and NLR family pyrin domain containing 3 (NLRP3)-induced pyroptosis play essential roles in the development of OA. In this study, we examine whether paroxetine, a well-known selective reuptake inhibitor of 5-hydroxytryptamine, can inhibit pyroptosis and reduce osteoclast formation, thereby delaying the destruction of knee joints. Methods We assayed the cytotoxic effects of paroxetine by the CCK8 assay. High-density cultures, in conjunction with quantitative polymerase chain reactions and western blots, were used to observe the effects of paroxetine on extracellular matrix synthesis and catabolism. NF-κB and pyroptosis-related signaling pathway proteins were examined by western blots and immunofluorescence assays. Furthermore, the effects of paroxetine on receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced osteoclast formation were also investigated. To investigate the protective effects of paroxetine on articular chondrocytes, a mouse model of OA in which the medial meniscus was destabilized, was established. Results Paroxetine delayed the catabolism of extracellular matrix components and promoted the anabolism of extracellular matrix components by chondrocytes. Paroxetine inhibited the interleukin 1 beta-induced activation of NF-κB and pyroptosis. In addition, it decreased the expression of osteoclast marker genes and reduced the formation of osteoclasts. Compared to control animals, mice treated with paroxetine showed slower disease progression. Conclusion Paroxetine can inhibit pyroptosis and reduce osteoclast formation, suggesting that it may have therapeutic effects in patients with OA.

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