Gastroenterology

Gastroenterology

Volume 140, Issue 1, January 2011, Pages 221-230.e3
Gastroenterology

Basic—Alimentary Tract
Anti–Tumor Necrosis Factor-α Antibodies Induce Regulatory Macrophages in an Fc Region-Dependent Manner

https://doi.org/10.1053/j.gastro.2010.10.008Get rights and content

Background & Aims

Anti–tumor necrosis factor (TNF)α antibodies are effective in treating patients with Crohn's disease whereas soluble TNFα receptors have not shown clinical efficacy; the mechanism that underlies these different effects is not clear. We examined the immunosuppressive effects of different anti-TNFα reagents on activated T cells.

Methods

We studied the effects of anti-TNFα antibodies infliximab and adalimumab, the soluble TNFα receptor etanercept, the pegylated F(ab') fragment certolizumab, and certolizumab–immunoglobulin (Ig)G on primary activated T cells. T cells were grown in isolation or in a mixed lymphocyte reaction (MLR). Proliferation was measured by 3H thymidine incorporation and apoptosis was examined using Annexin V labeling and a colorimetric assay for activated caspase-3. Macrophage phenotypes were assayed by flow cytometry and cytokine secretion.

Results

Infliximab and adalimumab reduced T-cell proliferation in an MLR whereas etanercept and certolizumab did not; this effect was lost after Fc receptors were blocked. The infliximab F(ab')2 fragment did not inhibit proliferation whereas certolizumab-IgG did inhibit proliferation. In the MLR, the antibodies against TNF induced formation of a new population of macrophages in an Fc region-dependent manner; these macrophages had an immunosuppressive phenotype because they inhibit proliferation of activated T cells, produce anti-inflammatory cytokines, and express the regulatory macrophage marker CD206.

Conclusions

Regulatory macrophages have immunosuppressive properties and an important role in wound healing. Antibodies against TNF induce regulatory macrophages in an Fc region-dependent manner. These functions of anti-TNFs might contribute to the resolution of inflammation.

Section snippets

Antibodies and Reagents

Infliximab, certolizumab, adalimumab, and etanercept were prepared according to the manufacturers' recommendations. Certolizumab-IgG was obtained from UCB (UCB, Brussels, Belgium), and IgG1k was obtained from Sigma (St. Louis, Missouri).

Cell Isolation and Culture

Peripheral blood mononuclear cells (PBMCs) from healthy volunteers were isolated by Ficoll Paque density-gradient centrifugation. After washing, monocytes were isolated by Percoll density-gradient centrifugation. CD3-positive T cells were isolated from PBMCs

Anti-TNFα Compounds Bind mTNFα on Activated T Cells to Varying Degrees

To assess binding of compounds to mTNFα, anti-TNFα compounds and IgG control were labeled with a fluorescent dye, and binding of fluorescent-labeled compounds to activated T cells was compared with binding to nonactivated cells. Binding of infliximab and adalimumab to mTNFα was highly efficient, binding of certolizumab was intermediate, and binding of etanercept was low compared with the IgG control (Figure 1).

Anti-TNFα Compounds With an Fc Region Suppress T-Cell Activation but Only in an MLR

We examined the effect of various anti-TNFα compounds on the proliferation of

Discussion

In the present study, we found that drugs used to target TNFα have different functional properties. The anti-TNFα antibodies bind to mTNFα on activated T cells and inhibit their proliferation but only in the presence of APCs. In contrast, a soluble TNFα receptor or F(ab')2 fragments of the anti-TNFα antibodies do not affect T-cell proliferation under the same circumstances. Our experiments show that the immunosuppressive properties of the anti-TNFα antibodies are dependent on their Fc region.

References (38)

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Conflicts of interest These authors disclose the following: Gijs van den Brink receives grants/research support from MSD, Ferring, and Giuliani; Daniel Hommes receives grants/research support and is a consultant for Abbott, MSD, UCB, Giuliani, Ferring, Serono, AstraZeneca, Falk, and Tramedico. The remaining authors disclose no conflicts.

Funding This study was financially supported by UCB.

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