Incorporation of a Ligand Peptide for Immune Inhibitory Receptor LAIR‐1 on Biomaterial Surfaces Inhibits Macrophage Inflammatory Responses

Abstract

Leukocyte-associated Ig-like receptor-1 (LAIR-1) is an inhibitory receptor broadly expressed on immune cells, with its ligands residing within the extracellular matrix protein collagen. In this study, we modify surfaces with a LAIR-1 ligand peptide (LP), and observe that macrophages cultured on LAIR-1 LP-conjugated surfaces exhibited significantly reduced secretion of inflammatory cytokines in response to proinflammatory stimuli that mimic an injured environment. These downregulated mediators include TNF-α, MIP-1α, MIP-1β, MIP-2, RANTES, and MIG. Knockdown of LAIR-1 using siRNA abrogates this inhibition of cytokine secretion, supporting the specificity of the inhibitory effect to this receptor. These results are the first to demonstrate that integration of LAIR-1 ligands with biomaterials could suppress inflammatory responses.

Extracellular Matrix‐Based Strategies for Immunomodulatory Biomaterials Engineering

“…To investigate the immunomodulatory function of LAIR1p, murine BMDMs were stimulated with LPS and IFNγ (to mimic an inflammatory response due to injury) and cultured on LAIR1p saturated surfaces. Results showed a 60% reduction of the pro‐inflammatory cytokine TNFα secreted by BMDM cultured on LAIR1p, compared to growth on non‐LAIR1p control surfaces ( Figure ) . These results were recapitulated for human monocyte–derived macrophages.…”

“…Isolated collagen peptide domains, with high affinity for LAIR‐1, have been synthetically produced to explore their potential as bioengineered materials for immunomodulation. Work from our own groups has showcased the effect of immobilizing a specific collagen LAIR‐1 binding domain on macrophage phenotype and reduction of inflammatory responses . In our study, we used a peptide first identified by Farndale and co‐workers, who showed the greatest level of inhibition of CD3‐induced T cell activation as well as significant inhibition of FcεR1‐induced degranulation of mast cells.…”

“…B) Levels of secreted cytokines from BMDM cultured on cysteine (control) or LAIR‐1 ligand peptide (LP) coated surfaces, with or without LPS/IFNγ stimulation. Adapted with permission . Copyright 2017, Wiley‐VCH.…”

Effects of Surface-Bound Collagen-Mimetic Peptides on Macrophage Uptake and Immunomodulation

“…LAIR1-LP was purchased from Genemed Synthesis. It has a sequence of C(GPP) 5 GAOGLRGGAGPOGPEGGKGAA GPOGPO(GPP) 5 -NH 2 (where "O" is hydroxyproline) and has been described in previous publications (Lebbink et al, 2009;Kim et al, 2017). The peptide includes the collagen III synthetic peptide III-30 sequence known to bind LAIR-1, two (GPP) 5 flanking regions to ensure triple helical conformation, and a N-terminal cysteine for surface conjugation to maleimide.…”

“…A collagen III peptide, referred to here as LAIR-1 ligand peptide (LAIR1-LP), in particular has high affinity for LAIR-1, exemplified by the greatest inhibition of CD3-induced T cell activation (Lebbink et al, 2009). Previously our research group has shown that macrophage interaction with LAIR1-LP functionalized surfaces significantly inhibits LPS-induced TNFα production when compared to cells cultured on control surfaces, for both human and mouse macrophages (Kim et al, 2017).…”