Anti-inflammatory effects of infliximab and methotrexate on peripheral blood and synovial fluid mononuclear cells: ex vivo study

Abstract

Objective

To investigate the effects of methotrexate (MTX) and the tumour necrosis factor inhibitor infliximab (IFX) on immune cells derived from peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) of inflammatory arthritis patients.

Method

Phytohaemagglutinin (PHA)-induced proliferation of healthy donors’ PBMCs and synovial intermediate monocytes (CD14⁺CD16⁺ cells) in SFMCs derived from psoriatic arthritis (PsA) and rheumatoid arthritis (RA) patients was determined by flow cytometry following co-culture with IFX and MTX. PHA-induced interferon-γ (IFN-γ) production in PBMCs was measured by enzyme-linked immunosorbent assay. The drugs’ effect on mRNA expression in SFMCs was determined by quantitative polymerase chain reaction.

Results

The combination of IFX 10 μg/mL + MTX 0.1 μg/mL had the strongest inhibitory effect on PBMC proliferation (91%), followed by MTX 0.1 μg/mL (86%) and IFX 10 μg/mL (49%). In PHA-stimulated PBMCs, IFN-γ production was reduced by IFX 10 μg/mL, MTX 0.1 μg/mL, and IFX 10 μg/mL + MTX 0.1 μg/mL by 68%, 90%, and 85%, respectively. In SFMCs, IFX 10 µg/mL significantly reduced CD14⁺CD16⁺ cells compared to medium (PsA 54%, p < 0.01; RA 46%, p < 0.05), while MTX had no effect on this population. IFX + MTX led to a similar suppression of CD14⁺CD16⁺ cells as achieved by IFX alone. The drugs had different impacts on SFMC gene expression.

Conclusion

Both IFX and MTX effectively inhibited PBMC proliferation and IFN-γ production, but only IFX reduced synovial monocytes and pro-inflammatory gene expression in SFMCs, suggesting a differential impact of IFX and MTX on critical inflammatory cell populations ex vivo.

Consent to participate

Informed consent was obtained from all individual participants included in the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical approval

The experiments were performed according to the protocols approved by Hospital Tel Aviv Sourasky Medical Center Ethics Committee (0182-18-TLV).

Availability of data and materials

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Authors’ contributions

SG and MR were responsible for performing the experiments and drawing the figures. SG and VF wrote the manuscript. MR, AP, IL, MA, and OE edited the manuscript. All authors read and approved the final manuscript.

Additional information

Funding

There was no external funding for this study.