Paramasivam Sivasakthi, Murugesan Janaranjani, Vedagiri Hemamalini, Perumal Senthamil Selvan, Ekambaram Sanmuga Priya
Department of Pharmaceutical Technology, University College of Engineering, Bharathidasan Institute of Technology campus, Anna University, Tiruchirappalli, 620 024, Tamil Nadu, India.
Medical Genomics lab, Department of Bioinformatics, Bharathiar University, Coimbatore, 641 046, India.
Cell Biochem Biophys. 2025 Jun;83(2):1919-1941. doi: 10.1007/s12013-024-01600-6. Epub 2024 Nov 22.
Danger-associated molecular patterns (DAMPs) are released on the onset of tissue injury or death, which tend to trigger innate immunity and regulate various immune pathways. Among the various DAMP molecules, S100A8 and S100A9 belonging to Ca binding proteins with EF-hands and Zn ion binding sites have been implicated in aggravating the pathogenesis of rheumatoid arthritis (RA), upon interaction with pattern recognition receptors (PRR) such as TLR4, RAGE and CD36 receptors. Thus, the present study aims to assess the effect of Ca or Zn ions on the interaction of S100A8 and S100A9 proteins towards the PRRs. Protein-protein interaction analysis showed that the TLR4-S100A8CaZn, TLR4-S100A8 Zn, RAGE-S100A8/A8Zn, RAGE-S100A8/A8Ca, CD36-S100A8Ca, and CD36-S100A9/A9Ca showed higher affinity against each other. The 100 ns molecular dynamics simulation showed that the TLR4-S100A8Ca, RAGE-S100A8/A8Ca and CD36-S100A8Ca complexes showed minimal fluctuations in their trajectory indicating that Ca bound complexes were more stable than the other complexes. Furthermore, SPR analysis showed that S100A9 exhibited higher binding affinity towards PRRs in the presence of Ca and Zn ions. Considering the fact that physiological levels of both Ca and Zn ions play a critical role in the binding of S100A8 and S100A9 proteins against the PRRs, it can be emphasized that the S100A9 and RAGE receptors could be the critical players in the RA pathogenesis due to its impeccable binding towards the PRRs in the presence of both Ca and Zn ions. Nonetheless, further in vivo, and in vitro studies are imperative to validate these findings and identify potential targets for RA treatment.
危险相关分子模式（DAMPs）在组织损伤或死亡发生时释放，往往会触发先天免疫并调节各种免疫途径。在各种DAMP分子中，属于具有EF手结构和锌离子结合位点的钙结合蛋白的S100A8和S100A9，在与Toll样受体4（TLR4）、晚期糖基化终末产物受体（RAGE）和CD36受体等模式识别受体（PRR）相互作用时，被认为会加重类风湿性关节炎（RA）的发病机制。因此，本研究旨在评估钙或锌离子对S100A8和S100A9蛋白与PRR相互作用的影响。蛋白质-蛋白质相互作用分析表明，TLR4-S100A8CaZn、TLR4-S100A8 Zn、RAGE-S100A8/A8Zn、RAGE-S100A8/A8Ca、CD36-S100A8Ca和CD36-S100A9/A9Ca之间显示出更高的相互亲和力。100纳秒的分子动力学模拟表明，TLR4-S100A8Ca、RAGE-S100A8/A8Ca和CD36-S100A8Ca复合物在其轨迹中显示出最小的波动，表明钙结合复合物比其他复合物更稳定。此外，表面等离子体共振（SPR）分析表明，在钙和锌离子存在的情况下，S100A9对PRR表现出更高的结合亲和力。鉴于钙和锌离子的生理水平在S100A8和S100A9蛋白与PRR的结合中起着关键作用，可以强调的是，S100A9和RAGE受体可能是RA发病机制中的关键因素，因为在钙和锌离子同时存在的情况下，它们与PRR的结合完美无缺。尽管如此，进一步的体内和体外研究对于验证这些发现并确定RA治疗的潜在靶点至关重要。
