Balancing immunogenicity with inflammation is a central tenet of vaccine design, especially for subunit vaccines that utilize traditional pro-inflammatory adjuvants. Here we report that by using a nanoparticulate peptide-based vaccine, immunogenicity and local inflammation could be decoupled. Self-assembled β-sheet-rich peptide nanofibers, previously shown to elicit potent antibody responses in mice, were found to be non-cytotoxic in vitro and, remarkably, elicited no measurable inflammation in vivo—with none of the swelling at the injection site, accumulation of inflammatory cells or cytokines, or production of allergic IgE that were elicited by an alum-adjuvanted vaccine. Nanofibers were internalized by dendritic cells and macrophages at the injection site, and only dendritic cells that acquired the material increased their expression of the activation markers CD80 and CD86. Immunization with epitope-bearing nanofibers elicited antigen-specific differentiation of T cells into T follicular helper cells and B cells into germinal center cells, as well as high-titer, high-affinity IgG that cross-reacted with the native protein antigen and was neutralizing in an in vitro influenza hemagglutination inhibition assay. These responses were superior to those induced by alum and comparable to those induced by complete Freund’s adjuvant. Thus, nanoparticulate assemblies may provide a new route to non-inflammatory immunotherapies and vaccines.

Epitope content plays a critical role in determining T cell and antibody responses to vaccines, biomaterials, and protein therapeutics, but its effects are nonlinear and difficult to isolate. Here, molecular self-assembly was used to build a vaccine with precise control over epitope content, in order to finely tune the magnitude and phenotype of T helper and antibody responses. Self-adjuvanting peptide nanofibers were formed by co-assembling a high-affinity universal CD4+ T cell epitope (PADRE) and a B cell epitope from Staphylococcus aureus at specifiable concentrations. Increasing the PADRE concentration from μM to mM elicited bell-shaped dose-responses that were unique to different T cell populations. Notably, the epitope ratios that maximized T follicular helper and antibody responses differed by an order of magnitude from those that maximized Th1 or Th2 responses. Thus, modular materials assembly provides a means of controlling epitope content and efficiently skewing the adaptive immune response in the absence of exogenous adjuvant; this approach may contribute to the development of improved vaccines and immunotherapies.

Chemicals and MaterialsAll experiments were conducted using chemicals of at least analytical reagent grade, received from Fisher Scientific and Sigma-Aldrich. Bis-(2-ethylhexyl) phosphoric acid (HDEHP) was received from Alfa-Aesar and purified using a Cu salt precipitation method 1 . Lanthanide stock solution was prepared using Ln nitrates of 99.99% purity. Experimental Section Laser machining of tubing and assembly of the deviceThe organic withdrawal channels were laser machined from 1/32" Teflon® FEP tubing. A Resontics RapidX 250 was utilized to machine all tubing substrates referenced within. A laser lathe stage was utilized to rotate the tubing 72º after the completion of each hole, until all 5 holes were drilled. Channel size was verified using a calibrated stereoscope. Figure S1 shows cross sections of tubing before and after machining. Figure S2 shows the details of how the device was assembled.

Blood coagulation often accompanies bacterial infections and sepsis and is generally accepted as a consequence of immune responses. Though many bacterial species can directly activate individual coagulation factors, they have not been shown to directly initiate the coagulation cascade that precedes clot formation. Here we demonstrated, using microfluidics and surface patterning, that the spatial localization of bacteria substantially affects coagulation of human and mouse blood and plasma. Bacillus cereus and Bacillus anthracis, the anthrax-causing pathogen, directly initiated coagulation of blood in minutes when bacterial cells were clustered. Coagulation of human blood by B. anthracis required secreted zinc metalloprotease InhA1, which activated prothrombin and factor X directly (not via factor XII or tissue factor pathways). We refer to this mechanism as 'quorum acting' to distinguish it from quorum sensing-it does not require a change in gene expression, it can be rapid and it can be independent of bacterium-to-bacterium communication.This paper describes a physical and biochemical mechanism responsible for regulating the initiation of human blood coagulation by bacteria. In vivo, coagulation often accompanies bacterial infections of the blood and is believed to be a consequence of immune and inflammatory responses 1-5 . Immune and inflammatory responses cause upregulation of tissue factor on the timescale of hours and lead to increased coagulation 6,7 . One of the few drugs available to treat septic shock, activated protein C, is also an anticoagulant 8 . This coagulation is believed to prevent dissemination of bacteria through the blood 9,10 but also results in serious vascular damage due to blockage and injury of blood vessels 8 . Coagulation accompanying bacterial infections of the blood is particularly relevant for people infected with anthrax, which involves sepsis and disseminated intravascular coagulation caused by the pathogen Bacillus Correspondence should be addressed to R.F.I. (r-ismagilov@uchicago.edu).. AUTHOR CONTRIBUTIONS C.J.K., J.Q.B., M.M., Y.B., R.R.P., T.R.K. and F.S. performed experiments; C.J.K., J.Q.B., M.M., Y.B., R.R.P., T.R.K., F.S., S.H.L., W.-J.T. and R.F.I. designed experiments and analyzed data; C.J.K., W.-J.T. and R.F.I. wrote the paper; A.P.P. and P.S. provided reagents. NIH Public Access Author ManuscriptNat Chem Biol. Author manuscript; available in PMC 2009 June 1. Published in final edited form as:Nat Chem Biol. 2008 December ; 4(12): 742-750. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript anthracis 4 . Here, we considered an alternative and complementary mechanism for the coagulation that accompanies infection: direct activation of the human coagulation cascade through activation of coagulation factors by bacteria.Many bacteria and bacterial components can directly activate individual human coagulation factors. However, direct initiation of the coagulation cascade and the formation of a propagating clot are not typically observed 11-17 ...

The lymph node is a structurally complex organ of the immune system, whose dynamic cellular arrangements are thought to control much of human health. Currently, no methods exist to precisely stimulate substructures within the lymph node or analyze local stimulus-response behaviors, making it difficult to rationally design therapies for inflammatory disease. Here we describe a novel integration of live lymph node slices with a microfluidic system for local stimulation. Slices maintained the cellular organization of the lymph node while making its core experimentally accessible. The 3-layer polydimethylsiloxane device consisted of a perfusion chamber stacked atop stimulation ports fed by underlying microfluidic channels. Fluorescent dextrans similar in size to common proteins, 40 and 70 kDa, were delivered to live lymph node slices with 284 ± 9 μm and 202 ± 15 μm spatial resolution, respectively, after 5 s, which is sufficient to target functional zones of the lymph node. The spread and quantity of stimulation were controlled by varying the flow rates of delivery; these were predictable using a computational model of isotropic diffusion and convection through the tissue. Delivery to two separate regions simultaneously was demonstrated, to mimic complex intercellular signaling. Delivery of a model therapeutic, glucose-conjugated albumin, to specific regions of the lymph node indicated that retention of the drug was greater in the B-cell zone than in the T-cell zone. Together, this work provides a novel platform, the lymph node slice-on-a-chip, to target and study local events in the lymph node and to inform the development of new immunotherapeutics.

The first microfluidic device for co-culture of two tissue slices under continuous recirculating flow was used to model tumor-induced immunosuppression.

Spatially defined arrays of droplets differ from bulk emulsions in that droplets in arrays can be indexed on the basis of one or more spatial variables to enable identification, monitoring, and addressability of individual droplets. Spatial indexing is critical in experiments with hundreds to millions of unique compartmentalized microscale processes--for example, in applications such as digital measurements of rare events in a large sample, high-throughput time-lapse studies of the contents of individual droplets, and controlled droplet-droplet interactions. This review describes approaches for spatially organizing and manipulating droplets in one-, two-, and three-dimensional structured arrays, including aspiration, laminar flow, droplet traps, the SlipChip, self-assembly, and optical or electrical fields. This review also presents techniques to analyze droplets in arrays and applications of spatially defined arrays, including time-lapse studies of chemical, enzymatic, and cellular processes, as well as further opportunities in chemical, biological, and engineering sciences, including perturbation/response experiments and personal and point-of-care diagnostics.

Active immunotherapies raising antibody responses against autologous targets are receiving increasing interest as alternatives to the administration of manufactured antibodies. The challenge in such an approach is generating protective and adjustable levels of therapeutic antibodies while at the same time avoiding strong T cell responses that could lead to autoimmune reactions. Here we demonstrate the design of an active immunotherapy against TNF-mediated inflammation using short synthetic peptides that assemble into supramolecular peptide nanofibers. Immunization with these materials, without additional adjuvants, was able to break B cell tolerance and raise protective antibody responses against autologous TNF in mice. The strength of the anti-TNF antibody response could be tuned by adjusting the epitope content in the nanofibers, and the T-cell response was focused on exogenous and non-autoreactive T-cell epitopes. Immunization with unadjuvanted peptide nanofibers was therapeutic in a lethal model of acute inflammation induced by intraperitoneally delivered lipopolysaccharide, whereas formulations adjuvanted with CpG showed comparatively poorer protection that correlated with a more Th1-polarized response. Additionally, immunization with peptide nanofibers did not diminish the ability of mice to clear infections ofListeria monocytogenes. Collectively this work suggests that synthetic self-assembled peptides can be attractive platforms for active immunotherapies against autologous targets.