title: Substrate Stiffness Regulates Proinflammatory Mediator Production through TLR4 Activity in Macrophages.
abstract: Clinical data show that disease adversely affects tissue elasticity or stiffness. While macrophage activity plays a critical role in driving disease pathology, there are limited data available on the effects of tissue stiffness on macrophage activity. In this study, the effects of substrate stiffness on inflammatory mediator production by macrophages were investigated. Bone marrow-derived macrophages were grown on polyacrylamide gels that mimicked the stiffness of a variety of soft biological tissues. Overall, macrophages grown on soft substrates produced less proinflammatory mediators than macrophages grown on stiff substrates when the endotoxin LPS was added to media. In addition, the pathways involved in stiffness-regulated proinflammation were investigated. The TLR4 signaling pathway was examined by evaluating TLR4, p-NF-κB p65, MyD88, and p-IκBα expression as well as p-NF-κB p65 translocation. Expression and translocation of the various signaling molecules were higher in macrophages grown on stiff substrates than on soft substrates. Furthermore, TLR4 knockout experiments showed that TLR4 activity enhanced proinflammation on stiff substrates. In conclusion, these results suggest that proinflammatory mediator production initiated by TLR4 is mechanically regulated in macrophages.
authors.affiliation: JFK Neuroscience Institute, JFK Medical Center, 65 James Street, Edison, New Jersey, 08820, United States of America.|Department of Neuroscience, Seton Hall University, 400 South Orange Avenue, South Orange, New Jersey, 07079, United States of America.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Previtera
authors.affiliation: JFK Neuroscience Institute, JFK Medical Center, 65 James Street, Edison, New Jersey, 08820, United States of America.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Sengupta
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D002478:Cells, Cultured; D004548:Elasticity; D020672:I-kappa B Proteins / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D015398:Signal Transduction; D013499:Surface Properties; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage
chemical_list: D020672:I-kappa B Proteins; D018836:Inflammation Mediators; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C000606205:Nfkbia protein, mouse; C498144:Rela protein, mouse; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha