Background/Purpose:

Macrophages contribute to the pathogenesis of rheumatoid arthritis (RA). They can display various states of activation or « polarization », characterized by distinct functions and plasticity. M1 polarization corresponds to the “classical”, pro-inflammatory activation as identified in RA. M2 “alternative” polarizations display immunoregulatory and wound-healing properties. Data concerning the effects of RA anti-cytokine biological drugs (bDMARDs) on macrophage polarization are scarce.

We aimed to assess in vitro modulation of macrophage polarization by RA bDMARDs.

Methods:

Blood monocytes from 15 healthy controls and 10 RA patients were positively sorted by CD14+ magnetic selection. Macrophages were Derived from Monocytes (MDM) by 5 days of culture in the presence of MCSF, and activated or not for 24h as M1 pro-inflammatory MDM (by LPS + IFNγ) or as M2 alternative MDM by IL10 or IL4, respectively M2(IL10) and M2(IL4). M1 MDM were cultured with or without bDMARDs.

We evaluated 2 anti-TNF agents (etanercept (ETA), adalimumab (ADA)), 1 anti-IL6R agent (tocilizumab (TCZ)), and 1 anti-CD20 agent (rituximab (RTX)) used as control monoclonal antibody. bDMARDs effects were assessed on M1 activation phase by flow cytometric analysis of membrane markers. Functional aspects of polarization were assessed by analysis of cytokine production in cell culture supernatants (cytometric bead array and ELISA) and phagocytosis (flow cytometry).

M1 MDM cultured in the presence of bDMARDs were compared to untreated M1 MDM by a Wilcoxon matched pairs test.

Results:

We validated membrane polarization markers in our culture model: CD40 and CD80 as M1 (LPS + IFNγ) markers; CD16, CD163, MerTK and CD64 as M2(IL10) markers, CD206 and CD200R as M2(IL4) markers.

When compared to MDM from healthy controls, MDM from RA patients displayed a biased plasticity: they significantly expressed higher levels of M1 markers after M1 activation and expressed lower levels of CD16 after differentiation or M1 and M2 activations.

Concerning the effect of bDMARDs on surface markers after M1 activation (M1 MDM): in RA patients and healthy controls, anti-TNF agents induced a significant decrease in M1 markers and a significant modulation in M2(IL10) markers. We observed (i) a decrease in CD40 and CD80, (ii) an increase in CD16, CD163, and MerTK, (iii) a decrease in CD64 with ETA and an increase with ADA. TCZ induced a slight but significant decrease in CD40 and an increase in CD64. RTX only increased CD64.

Anti-TNF agents led to a significant modulation of cytokines produced by M1 MDM from healthy controls: we observed a decrease in TNFα, IL6, IL12 and IL10 levels, and an increase in TGFβ. TCZ mainly affected IL6 and TNFα productions with a significant decrease. No significant effect was observed with RTX.

In healthy controls, phagocytosis was superior in M2(IL10) and M2(IL4) activated MDM than in M1 MDM. Anti-TNF agents, but neither TCZ nor RTX, induced an increase of phagocytosis in M1 MDM.

Conclusion:

Anti-TNF agents modulate the phenotype of MDM from healthy donors as well as from RA patients. They up-regulate M2 alternative properties and downregulate M1 inflammatory properties in macrophages.

« Back to 2017 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-tnf-agents-induce-alternative-macrophages/