Comparative study of HO-1 expressing synovial lining cells between RA and OA

Abstract

Objectives

We aimed to clarify the characteristics of heme oxygenase (HO)-1 expressing cells in the synovium from rheumatoid arthritis (RA) and osteoarthritis (OA), and to investigate the co-expression of HO-1 and IgG-Fc/HLA-DR complex.

Methods

The characteristics of HO-1 expressing cells in the synovium were investigated by using immunohistochemistry. The co-expression of HO-1 and IgG-Fc/HLA-DR complex was examined by an in situ proximity ligation assay (PLA) with immunofluorescence. HO-1 mRNA was investigated by reverse transcription-polymerase chain reaction.

Results

The number of HO-1⁺ cells from the RA synovium is higher than that from OA synovium. The double positive cells of HO-1 and IgG-Fc/HLA-DR complex were detected by the in situ PLA with immunofluorescence in RA synovium. HO-1 mRNA was detected in both RA and OA synovium.

Conclusion

A portion of HO-1⁺ cells with IgG-Fc/HLA-DR complex in lining layer of RA may be concluded as one of antigen presenting cells in RA and may be involved in production of RF.

Keywords:

• Heme Oxygenase-1
• rheumatoid arthritis
• synovial lining layer
• synovitis
• macrophage

Acknowledgments

We thank Miss Hiromi Murata and Mrs. Junko Takeda for excellent technological supports. The authors thank Wiley editing services for the excellent editing of this manuscript.

Conflict of interest

None.

Additional information

Funding

This work was supported by Grant-in-Aid for Scientific Research (C) (JP17K08736) in Japan and a Grant-in-Aid for Young Scientists (JP19K16577) of Japan Society for the Promotion Science (JSPS).