Effect of Tyrosine-Containing Self-Assembling β-Sheet Peptides on Macrophage Polarization and Inflammatory Response

Self-assembling peptides (SAPs) are fully defined nanobiomaterials offering unprecedented opportunities to control nanostructure and chemical attributes to investigate and manipulate cellular signals. To investigate the influence of chemical and morphological characteristics on inflammatory signaling in native immunity, we designed five β-sheet SAPs: EFEFKFEFK (<b>EF8</b>), <b>Y</b>EFEFKFEFK (<b>YEF8</b>), EFEFKFEFK<b>Y</b> (<b>EF8Y</b>), <b>Y</b>EFEFKFEFK<b>Y</b> (<b>YEF8Y</b>), and E<b>Y</b>EFKFEFK (<b>EYF8</b>) (F: phenylalanine; E: glutamic acid; K: lysine, <b>Y</b>: tyrosine). The position of tyrosine in the peptide sequence dictated the self-assembly into nanostructures, with all SAPs self-assembling into thin constituent nanofibers with <i>d</i> ≈ 3.8 ± 0.4 nm, and sequences <b>YEF8</b> and <b>EF8</b> showing a propensity for associative bundling. These distinct SAPs induced contrasting inflammatory responses of monocytic model THP-1 cells-derived macrophages (MΦs). Presence of soluble <b>EF8</b> nanofibers (at 2 mM) induced an anti-inflammatory response and polarization toward an M2 state, whereas <b>YEF8</b> (at 2 mM) displayed a tendency for inducing a pro-inflammatory response and polarization toward an M1 state. <b>EF8Y</b>, <b>YEF8Y</b>, and <b>EYF8</b> SAPs did not induce an inflammatory response in our models. These results were validated using peripheral blood mononuclear cells (PBMCs)-derived MΦs from human donors, confirming the critical role of <b>EF8</b> and <b>YEF8</b> SAPs as possible orchestrators of the repair of tissues or inducers of pro-inflammatory state, respectively. The same MΦs polarization responses from THP-1-derived MΦs cultured on 20 mM hydrogels were obtained. These findings will facilitate the utilization of this family of SAPs as immunomodulatory nanobiomaterials potentially changing the course of inflammation during the progression of various diseases.