Adhesive substrate-modulation of adaptive immune responses Abhinav P. Acharya a,1 , Natalia V. Dolgova b , Michael J. Clare-Salzler c , Benjamin G. Keselowsky b, * a Materials Science and Engineering, University of Florida, P.O. Box 116400, Gainesville, Florida, 32611-6400, USA b J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida,130 BME/PO Box 116131, Gainesville, Florida, 32611-6131, USA c Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, P.O. Box 100275, Gainesville, Florida, 32610-0275, USA article info Article history: Received 27 June 2008 Accepted 28 August 2008 Available online 30 September 2008 Keywords: Cell adhesion Extracellular matrix (ECM) Integrin Immune response Inflammation Immunomodulation abstract While it is well-known that adsorbed proteins on implanted biomaterials modulate inflammatory responses, modulation of dendritic cells (DCs) via adhesion-dependent signaling has only been begun to be characterized. In this work, we demonstrate that adhesive substrates elicit differential DC maturation and adaptive immune responses. We find that adhesive substrates support similar levels of DC adhesion and expression of stimulatory and co-stimulatory molecules. Conversely, DC morphology and differential production of pro- and anti-inflammatory cytokines (IL-12p40 and IL-10, respectively) is adhesive substrate-dependent. For example, DCs cultured on collagen and vitronectin substrates generate higher levels of IL-12p40, whereas DCs cultured on albumin and serum-coated tissue culture-treated substrates produce the higher levels of IL-10 compared to other substrates. Additionally, our results suggest substrate-dependent trends in DC-mediated allogeneic CD4 þ T-cell proliferation and T-helper cell type responses. Specifically, we show that substrate-dependent modulation of DC IL-12p40 cytokine production correlates with CD4 þ T-cell proliferation and T h 1 type response in terms of IFN-g producing T-helper cells. Furthermore, our results suggest substrate-dependent trends in DC-mediated stimulation of IL-4 producing T-cells, but this T h 2 type response is not dependent on DC production of IL-10 cytokine. This work has impact in the rational design of biomaterials for diverse applications such as tissue- engineered constructs, synthetic particle-based vaccines and the ex vivo culture of DCs for immunotherapies. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction There is enormous potential for implanted medical devices that bring together synthetic biomaterial and biological components for use in numerous applications such as tissue-engineered constructs, combination products (e.g., drug-eluting stents) and therapeutic vaccines. While both the biomaterial and biological component may be approved for use by the U.S. Food and Drug Administration or other regulatory agencies, and the body’s response to each may be well-known, the combination of the two can give rise to unforeseen immune responses. For example, inflammatory responses to the implanted material can alter adaptive immune responses to the biological components [1–4]. Assessing modula- tion of dendritic cell (DC) responses resulting from interactions with biomaterials is critical, as DCs are key regulators of the innate and adaptive immune system. Furthermore, interactions of DCs with biomaterials have been demonstrated to modulate DC func- tions [5–7]. Upon implantation, numerous proteins are quickly adsorbed onto biomaterials, including extracellular matrix proteins. Some of these (e.g., fibronectin, fibrinogen, vitronectin) have been shown to modulate inflammatory responses [8–13]. Dendritic cell adhesion to extracellular matrix proteins is of therefore an important consideration in biomaterials. Additionally, DC adhesion to extracellular matrix proteins is of interest physio- logically because DCs reside for much of their lifetime in connective tissues comprised largely of extracellular matrix proteins in both lymphoid and non-lymphoid organs, which may influence immune responses in the wake of injury, disease or tissue transplantation. However, despite its significance, modulation of innate and adap- tive immune responses by DCs upon adhesion to extracellular matrix proteins has only been begun to be characterized. Dendritic cells are critical for both immunity and tolerance and are involved in guiding innate and adaptive immune responses [14,15]. Dendritic cells act as sentinels, constantly patrolling the body and presenting both self and non-self antigens to lympho- cytes such as B-cells and T-cells [16–18]. Immature DCs (iDCs) mature/activate following interaction with pathogen associated molecular patterns or ‘‘danger signals’’ [14,15] as well as * Corresponding author. Tel.: þ1 352 273 5878; fax: þ1 352 392 9791. E-mail addresses: abhinav9@ufl.edu (A.P. Acharya), bgk@ufl.edu (B.G. Keselowsky). 1 Tel.: þ1 352 273 6938. Contents lists available at ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2008.08.040 Biomaterials 29 (2008) 4736–4750