Toll-like Receptor 2-Dependent NF-κB/AP-1 Activation by Damage-Associated Molecular Patterns Adsorbed on Polymeric Surfaces

Abstract

The foreign body reaction is a chronic inflammatory response to an implanted biomaterial that ultimately leads to fibrous encapsulation of the implant. It is widely accepted that the host response to implanted biomaterials is largely dependent on the species and conformations of proteins adsorbed onto the material surface due to the adsorbate's role in mediating cellular interactions with the implanted material. While the cellular response to adsorbed serum-derived proteins has been studied extensively, the presence of endogenous, matrix-and cell-derived mediators of inflammation within the adsorbed protein layer and their impact on cell−material interactions is not well-understood. Damage associated molecular patterns (DAMPs) are endogenous ligands released by stressed or damaged tissues to stimulate sterile inflammatory responses via Toll-like receptors (TLRs) and other pattern recognition receptors. The present study investigated the potential role of tissue-derived, pro-inflammatory stimuli in macrophage responses to biomaterials using cell lysate as a complex source of cell-derived DAMPs and poly(methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS) films as model biomaterials. We show that lysate-adsorbed PMMA and PDMS surfaces strongly induced NF-κB/AP-1 transcription factor activity and pro-inflammatory cytokine secretion in the RAW-Blue macrophage cell line compared to serum-adsorbed surfaces. Lysate-dependent NF-κB/AP-1 activation and cytokine expression were strongly attenuated by TLR2 neutralizing antibodies, while TLR4 inhibition resulted in a modest reduction. These data suggest that DAMPs, in their adsorbed conformations on material surfaces, may play a significant role in macrophage activation through TLR signaling, and that TLR pathways, particularly TLR2, merit further investigation as potential therapeutic targets to modulate host responses to implanted biomaterials.

Protein Adsorption on Surfaces Functionalized with COOH Groups Promotes Anti-inflammatory Macrophage Responses

“…The COOH surfaces also adsorbed relatively less pro-inflammatory proteins than the NH 2 and TCPS surfaces from the medium. A previous report showed that the relative amount of adsorbed DAMPs was related to the extent of NF-κB activity and pro-inflammatory responses, and this suggests that the reduced presence of DAMPs on COOH surfaces could have helped reduce the pro-inflammatory macrophage responses . Interestingly, there were no significant differences in some proteins that have been cited for their role in the immune response, such as immunoglobulins and complement proteins (see Table S2 for all one-way ANOVA results). , …”

“…A previous report showed that the relative amount of adsorbed DAMPs was related to the extent of NF-κB activity and pro-inflammatory responses, and this suggests that the reduced presence of DAMPs on COOH surfaces could have helped reduce the proinflammatory macrophage responses. 63 Interestingly, there were no significant differences in some proteins that have been cited for their role in the immune response, such as immunoglobulins and complement proteins (see Table S2 for all one-way ANOVA results). 11,21 From the initial list of proteins, we narrowed our search using the Gene Ontology database to find proteins under the cellular component category of extracellular region since we wanted to understand the role of proteins that are typically found outside the cells; the number found in the extracellular region for each surface is also listed in Table 3.…”

Inhibition Mir‐92a Alleviates Oxidative Stress and Apoptosis of Alveolar Epithelial Cells Induced by Lipopolysaccharide Exposure through TLR2/AP‐1 Pathway

“…Khan et al [ 15 ] showed that Anomalin could inhibit AP-1 to relieve mechanical pain and inhibit leukocyte infiltration in ALI rats. And AP-1 is regulated by TLR2 [ 16 , 17 ].…”

Biomaterials Going Strong in Canada for Half a Century

“…Understanding how the body recognizes and reacts to the implanted biomaterials has been considered to be a “holly grail” of biomaterial science, as it may lead to approaches that minimize chronic inflammatory response and ultimately minimized fibrosis. In this issue, Lindsay Fitzpatrick’s laboratory delineates a mechanism of recognition, by the Toll-like receptors, of damage-associated molecular patterns adsorbed on polymeric surfaces …”

“…In this issue, Lindsay Fitzpatrick's laboratory delineates a mechanism of recognition, by the Toll-like receptors, of damage-associated molecular patterns adsorbed on polymeric surfaces. 17 Canadian scientists are also leading in the development of smart food packaging that can inform us on the state of the food inside the package or keep the food fresh without adding preservatives to it. In the future, it might be possible for the packaging material to warn us when the food inside has gone bad or become contaminated with bacteria, potentially saving lives.…”