AUTHOR=Saffery Nik Syazana Izyan , Genasan Krishnamurithy , Chan Chee Ken , Ayob Khairul Anwar , Teo Seow Hui , Al-Fayyadh Mohamed Zubair Mohamed , Othman Iekhsan , Abidin Syafiq Asnawi Zainal , Raman Murali Malliga , Raghavendran Hanumantha Rao Balaji , Kamarul Tunku TITLE=Typical response of CD14++CD16– monocyte to knee synovial derived mediators as a key target to overcome the onset and progression of osteoarthritis JOURNAL=Frontiers in Medicine VOLUME=9 YEAR=2022 URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.904721 DOI=10.3389/fmed.2022.904721 ISSN=2296-858X ABSTRACT=Objective

Synovitis with increased infiltration of immune cells is observed in osteoarthritis (OA). Given the inflammatory condition of synovitis, we explored the protein profile of OA synovium (OAS) and its effect on circulating monocytes activation, migration, and functional commitments.

Methods

Knee-synovium was acquired from end-stage OA (N = 8) and trauma patients (Trauma baseline control: TBC; N = 8) for characterization using H&E histology, IHC (iNOS), LCMS-QTOF, and MALDI-imaging. Response of peripheral blood monocytes to OAS conditioned-media (OACM) was observed using transwell (n = 6). The migrated cells were captured in SEM, quantified using phase-contrast microphotographs, and their activation receptors (CCR2, CXCR2, CX3CR1, and CD11b), pro-inflammatory genes, and phagocytic potential were studied using flow cytometry, gene expression array/qPCR, and latex beads (LB) phagocytosis assay, respectively.

Results

The Venn diagram displayed 119 typical proteins in OAS, while 55 proteins in TBCS. The STRING protein network analysis indicated distinctive links between proteins and gene ontology (GO) and revealed proteins associated with leukocyte-mediated immunity in OAS as compared to TBC. The MALDI-imaging showed typical localized proteins at 2234.97, 2522.61, 2627.21, 3329.50, and 3539.69 m/z and IHC confirmed pro-inflammatory iNOS expression in OA synovium. CD14++CD16– classical monocytes significantly migrated in OACM and expressed CCR2, CXCR2, and CD11b receptors, TNFRSF11A, MAPK1, S100A8, HSPB1, ITGAL, NFATC1, IL13RA1, CD93, IL-1β, TNF-α, and MYD88 genes and increased LB uptake as compared to SFM.

Conclusion

Our findings suggest that the differential protein profile of OA synovium and the classical monocytes migrated, activated, and functionally committed in response to these mediators could be of therapeutic advantage.