Controlling the Origins of Inflammation with a Photoactive Lipopeptide Immunopotentiator

Abstract

Inflammatory immune responses are mediated by signaling molecules that are both produced and recognized across highly heterogeneous cell populations. As such, studying inflammation using traditional immunostimulants is complicated by paracrine and autocrine signaling that obscures the origin of a propagating response. To address this challenge, we developed a small molecule probe that can photosensitize immune cells allowing for light-mediated inflammation. We use this probe to control the origin of inflammation using light. Following this motif, inflammation was induced originating from fibroblasts or dendritic cells. We report the contributions of fibroblasts and dendritic cells in initiating inflammation in heterogeneous co-culture which provides insights for the future development of vaccines and treatment of inflammation. Keywords photochemistry; immunoassays; inflammation; peptidomimetics; lipidsInflammation is an important component in vaccine and wound healing therapies, but also plays a role in diseases such as diabetes, heart disease and sepsis. In each inflammatory response, functionally diverse populations of immune cells act in concert to effect a response with nuances such as timing, [1] location, [2] and motility patterns [3] of each cell phenotype all affecting propagation of the resulting signal. Methods to study inflammation initiated from different cell populations disrupt these factors; either isolated cell types are primed (activated) with immunostimulants and washed extensively before introduction into heterogeneous co-culture, [4] or immunostimulant-exposed cells are separated using physical barriers such as transwell membranes. [5] These methods have been used to discover logic gates and signaling networks that control immune responses [6] resulting in the development of increasingly sophisticated immunotherapies. [7,8] However, removal of critical signaling molecules during post-priming washing steps and disruption of cell-cell contacts often hinder analysis and obscure signals reliant on precise temporal or cell-specific inputs. For instance, cell priming times range from 3-18 h, [9,10] however, early proinflammatory cytokine transcription begins in as little as 15 min, [11,12] implying that the initial portion of Correspondence to: Aaron P. Esser-Kahn, aesserka@uci.edu. Supporting information for this article is given via a link at the end of the document. HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript inflammatory signaling is effectively erased during a typical cell priming experiment. A method for de novo transduction of specific immune cells in their native environment would therefore be useful as adjacent cells would experience the complete temporal profile of cytokine signaling resulting from stimulation while also maintaining fidelity between cellcell contacts. A similar problem was faced in the field of neuroscience, where identical receptors on neurons make it difficult to determine activity of subpopulations. Light-guided acti...

Light GuidedIn-vivoActivation of Innate Immune Cells with Photocaged TLR 2/6 Agonist

“…As the agonist stays colocalized, we can have the spatial control of agonist presentation and immune cell activation. 16 In initial experiments, we observed that high concentration of the TRIGIR compound, NPPOC-Pam 2 CSK 4 (1, Figure 1a), incubation overnight resulted in higher amount of labeling of the agonist (Figure 1d). However, this also resulted in higher background activation of the cells (Figure 1e).…”

“…[11][12][13][14][15] Recently, we developed a method to tag and remotely induce a guided immune response (TRIGIR) with a photo-caged TLR2/6 agonist. 16 TRIGIR allows for selective labeling of cells, followed by remote light activation. Here we use the TRIGIR method for in vivo light-based activation to control the migration of dendritic cells.…”

Optical Control of Cytokine Signaling via Bioinspired, Polymer-Induced Latency

“…[9][10][11][12][13][42][43][44][45][46] Deiters and coworkers previously demonstrated reversible photocaging strategies for enzymes based on nitrobenzyl linkages, 47 while Esser-Kahn and coworkers have demonstrated related approaches to photo-activate smaller lipopeptide Toll-like receptor (TLR) agonists. 48,49 Likewise, Garcia, 50 Hubbell, 51 and Wittrupp 52 have recently developed affinity-targeted cytokine fusions with high cell-or tissue-specific activity. Combining elements of these approaches, here we describe a bioinspired strategy for polymer-induced cytokine latency and photo-induced reactivation.…”

Beyond the brain: Optogenetic control in the spinal cord and peripheral nervous system

“…Preliminary reports have also described how optogenetics may be used to study cancer (5,133), fertilization (42), insulin secretion (9,43,44), endothelial regulation of vasoconstriction (50), and immune function (134), opening the door to a diverse host of targets for manipulation ( Fig. 3).…”