Transepithelial delivery of insulin conjugated with phospholipid-mimicking polymers via biomembrane fusion-mediated transcellular pathways

Curcumin Alleviates Osteoarthritis Through the p38MAPK Pathway: Network Pharmacological Prediction and Experimental Confirmation

Objective

Osteoarthritis (OA) is a common degenerative disease worldwide. While curcumin has shown therapeutic effects on OA, its mechanism remains unknown. This study aimed to investigate the molecular mechanism of curcumin in treating OA through network pharmacology and both in vivo and in vitro experiments.

Methods

Curcumin-related targets were obtained using the HERB and DrugBank databases. GeneCards and DisGeNET were used to build a target database for OA. The STRING database was employed to construct protein-protein interaction networks and analyze related protein interactions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and gene ontology enrichment analyses of core targets were performed using Metascape. In addition, Autodock software was utilized for molecular docking validation of curcumin and disease targets. Further validation of the main findings was conducted through in vitro and in vivo experiments. In the in vitro experiments, an inflammation model was constructed through nitric oxide donor (SNP) stimulation of chondrocytes. Subsequently, the regulatory effects of curcumin on core targets and signaling pathways were validated using Western blotting and immunofluorescence staining techniques. In the in vivo experiments, an OA model was established by performing medial meniscectomy on male Sprague-Dawley rats. The therapeutic effects were evaluated using enzyme-linked immunosorbent assays, histologic staining, and micro-computed tomography (micro-CT) techniques.

Results

Core targets of curcumin relevant to OA therapy included tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-6, matrix metalloproteinase 9 (MMP-9), B-cell lymphoma 2 (BCL-2), and caspase-3. The major biological processes involved oxidative stress and apoptotic processes, among others. The p38 mitogen-activated protein kinase (p38/MAPK) pathway was identified as the most likely pathway involved. In vitro experiments showed that curcumin significantly reduced oxidative stress levels, inhibited the expression of inflammatory factors IL-6 and Cyclooxygenase-2 (COX-2) and downregulated the expression of MMP-9 and MMP-1. In addition, curcumin was found to regulate the expression of BCL-2 and caspase-3 through the p38/MAPK pathway, inhibiting chondrocyte apoptosis. In vivo animal experiments demonstrated that curcumin significantly reduced the expression of OA-related factors (IL-1, IL-6, and TNF-α). Histological analysis and micro-CT results revealed that curcumin treatment significantly increased cartilage thickness, improved cartilage morphology, structure, and function, inhibited cartilage degradation, and enhanced the resorption of subchondral bone in the knee joints of rats with OA.

Conclusion

Curcumin regulates oxidative stress and maintains mitochondrial function, thereby protecting chondrocyte guard. In addition, curcumin attenuates the inflammatory response of chondrocytes by inhibiting the phosphorylation of P38MAPK, slowing down the breakdown of the extrachondral matrix while preventing apoptosis of chondrocytes. Additionally curcumin attenuated cartilage degradation and bone damage while helping to boost bone density.

Zwitterionic Biomaterials

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.