Vaccine development has progressed significantly and has moved from whole microorganisms to subunit vaccines that contain only their antigenic proteins. Subunit vaccines are often less immunogenic than whole pathogens; therefore, adjuvants must amplify the immune response, ideally establishing both innate and adaptive immunity. Incorporation of antigens into biomaterials, such as liposomes and polymers, can achieve a desired vaccine response. The physical properties of these platforms can be easily manipulated, thus allowing for controlled delivery of immunostimulatory factors and presentation of pathogen-associated molecular patterns (PAMPs) that are targeted to specific immune cells. Targeting antigen to immune cells via PAMP-modified biomaterials is a new strategy to control the subsequent development of immunity and, in turn, effective vaccination. Here, we review the recent advances in both immunology and biomaterial engineering that have brought particulate-based vaccines to reality.

There is an urgent need for new strategies to combat infectious diseases in developing countries. Many pathogens have evolved to elude immunity and this has limited the utility of current therapies. Additionally, the emergence of co-infections and drug resistant pathogens has increased the need for advanced therapeutic and diagnostic strategies. These challenges can be addressed with therapies that boost the quality and magnitude of an immune response in a predictable, designable fashion that can be applied for wide-spread use. Here, we discuss how biomaterials and specifically nanoscale delivery vehicles can be used to modify and improve the immune system response against infectious diseases. Immunotherapy of infectious disease is the enhancement or modulation of the immune system response to more effectively prevent or clear pathogen infection. Nanoscale vehicles are particularly adept at facilitating immunotherapeutic approaches because they can be engineered to have different physical properties, encapsulated agents, and surface ligands. Additionally, nanoscaled point-of-care diagnostics offer new alternatives for portable and sensitive health monitoring that can guide the use of nanoscale immunotherapies. By exploiting the unique tunability of nanoscale biomaterials to activate, shape, and detect immune system effector function, it may be possible in the near future to generate practical strategies for the prevention and treatment of infectious diseases in the developing world.

Dendritic-cell (DC) targeted antigen delivery systems hold promise for enhancing vaccine efficacy and delivery of therapeutics. However, it is not known how the number and density of targeting ligands on such systems may affect DC function and subsequent T cell response. We modified the surface of biodegradable nanoparticles loaded with antigen with different densities of the mAb to the DC lectin DEC-205 receptor and assessed changes in the cytokine response of DCs and T cells. DEC-205 targeted nanoparticles unexpectedly induced a differential cytokine response that depended on the density of ligands on the surface. Strikingly, nanoparticle surface density of DEC-205 mAb increased the amount of anti-inflammatory, IL-10, produced by DCs and T cells. Boosting mice with DEC-205 targeted OVA-nanoparticles after immunization with an antigen in CFA induced a similar pattern of IL-10 response. The correlation between DC production of IL-10 as a function of the density of anti-DEC-205 is shown to be due to cross-linking of the DEC-205 receptor. Cross-linking also increased DC expression of the scavenger receptor CD36, and blockade of CD36 largely abrogated the IL-10 response. Our studies highlight the importance of target ligand density in the design of vaccine delivery systems.

Atypical invariant chain (Ii)3 CLIP fragments (CLIP2) have been found in association with HLA-DQ2 (DQ2) purified from cell lysates. We mapped the binding register of CLIP2 (Ii 96-104) to DQ2 and found proline at the P1 position, in contrast to the canonical CLIP1 (Ii 83-101) register with methionine at P1. CLIP1/2 peptides are the predominant peptide species, even for DQ2 from HLA-DM (DM)-expressing cells. We hypothesized that DQ2-CLIP1/2 might be poor substrates for DM. We measured DM-mediated exchange of CLIP peptides for high affinity indicator peptides and found it is inefficient for DQ2 compared to HLA-DR3 (DR3). DM-DQ binding and DM chaperone effects on conformation and levels of DQ are also reduced for DQ2, compared to DQ1. We suggest that the unusual interaction of DQ2 with Ii and DM may provide a basis for the known disease associations of DQ2.

Purpose-Combined therapeutic and diagnostic agents, "theranostics" are emerging valuable tools for noninvasive imaging and drug delivery. Here, we report on a solid biodegradable multifunctional nanoparticle that combines both features.Methods-Poly(lactide-co-glycolide) nanoparticles were engineered to confine superparamagnetic iron oxide contrast for magnetic resonance imaging while enabling controlled drug delivery and targeting to specific cells. To achieve this dual modality, fatty acids were used as anchors for surface ligands and for encapsulated iron oxide in the polymer matrix.Results-We demonstrate that fatty acid modified iron oxide prolonged retention of the contrast agent in the polymer matrix during degradative release of drug. Antibody-fatty acid surface modification facilitated cellular targeting and subsequent internalization in cells while inducing clustering of encapsulated fatty-acid modified superparamagnetic iron oxide during particle formulation. This induced clustered confinement led to an aggregation within the nanoparticle and, hence, higher transverse relaxivity, r 2 , (294 mM −1 s −1 ) compared with nanoparticles without fatty-acid ligands (160 mM −1 s −1 ) and higher than commercially available superparamagnetic iron oxide nanoparticles (89 mM −1 s −1 ).Conclusion-Clustering of superparamagnetic iron oxide in poly(lactide-co-glycolide) did not affect the controlled release of encapsulated drugs such as methotrexate or clodronate and their subsequent pharmacological activity, thus highlighting the full theranostic capability of our system. KeywordsPLGA; iron oxide; clustered; targeted; methotrexate; clodronate Theranostic constructs combine both therapeutic and diagnostic properties in a single platform (1,2). As such, these systems have recently gained significant attention because of their promise in visualizing therapeutic intervention. Recent progress in both the nanotechnology fabrication front and diagnostic modalities are advancing the design and application of these tools for different disease states (3-7). The attractive aspects of the NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript approach stems from the idea that such systems can simultaneously function to improve drug therapy by localizing drug delivery (6,(8)(9)(10)(11), guide the delivery process by visualizing the biodistribution of nanoparticle-based therapies and hence facilitate "positioning the dose" for early-stage particulate-based drug development process (6,(8)(9)(10)(11), or improve upon conventional therapies such as radiation or hyperthermia (12)(13)(14). Toward that goal of combining multiple functionalities into a single platform, one of the encumbering issues remains optimization of the therapeutic and imaging agent concentrations in the theranostic platform for realization of effective localized drug delivery and noninvasive imaging. Progress in this area, especially with safe biodegradable materials will yield an optimal platform that function effectively for both treat...

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The CD8 co-receptor influences T cell recognition and responses in both anti-tumor and anti-viral immunity. During evolution in the ancestor of humans and chimpanzees, the CD8B gene acquired two additional exons. As a result, in humans, there are four CD8β splice variants (M1 to M4) that differ in their cytoplasmic tails. The M-1 isoform which is the equivalent of murine CD8β, is predominantly expressed in naïve T cells, whereas, the M-4 isoform is predominantly expressed in effector memory T cells. The characteristics of the M-4 isoform conferred by its unique 36 amino acid cytoplasmic tail are not known. In this study, we identified a dihydrophobic leucine-based receptor internalization motif in the cytoplasmic tail of M-4 that regulated its cell surface expression and downregulation after activation. Further the M-4 cytoplasmic tail was able to associate with ubiquitinated targets in 293T cells and mutations in the amino acids NPW, a potential EH domain binding site, either enhanced or inhibited the interaction. In addition, the M-4 tail was itself mono-ubiquitinated on a lysine residue in both 293T cells and a human T cell line. When peripheral blood human T cells expressed CD8αβ M-4, the frequency of MIP-1β secreting cells responding to antigen presenting cells was two-fold higher as compared to CD8αβ M-1 expressing T cells. Thus, the cytoplasmic tail of the CD8β M-4 isoform has unique characteristics, which likely contributed to its selective expression and function in human effector memory T cells.

The CD8αβ coreceptor influences CD8 T cell recognition and responses in anti-tumor and -viral immunity. The ancestor to the human and chimpanzee CD8β gene acquired two additional exons absent in the mouse that lead to the expression of multiple isoforms (M1-M4) as a result of alternative splicing. In humans these isoforms differ in their cytoplasmic tails and in their expression pattern. The M-1 isoform is predominant in naïve T cells whereas M-4 is predominant in effector memory T cells. To study functional differences we are co-transducing CD8α, each CD8β isoform, and MHCI restricted NY-ESO-1 specific TCR into human CD4+ T cells and measuring cytokine production after activation. We have found differences in induction of cytokine producing cells such as the MIP-1β chemokine with different isoforms. The M-4 isoform cytoplasmic tail has unique sorting motifs that regulate its cell surface expression and it is modified by phosphorylation after activation. The cytoplasmic tail of M-4 could associate with ubiquitinated substrates in 293T cells and was itself mono-ubiquitinated. The M-4 isoform has unique properties that likely favored its selection in effector memory T cells.