Protein cage architectures such as virus capsids and ferritins are versatile nanoscale platforms amenable to both genetic and chemical modification. Incorporation of multiple functionalities within these nanometer-sized protein architectures demonstrate their potential to serve as functional nanomaterials with applications in medical imaging and therapy. In the present study, we synthesized an iron oxide (magnetite) nanoparticle within the interior cavity of a genetically engineered human H-chain ferritin (HFn). A cell-specific targeting peptide, RGD-4C which binds alphavbeta3 integrins upregulated on tumor vasculature, was genetically incorporated on the exterior surface of HFn. Both magnetite-containing and fluorescently labeled RGD4C-Fn cages bound C32 melanoma cells in vitro. Together these results demonstrate the capability of a genetically modified protein cage architecture to serve as a multifunctional nanoscale container for simultaneous iron oxide loading and cell-specific targeting.

γδ T cells are innate immune cells that participate in host responses against many pathogens and cancers. Recently, phosphoantigen-based drugs, capable of expanding γδ T cells in vivo, entered clinical trials with the goal of enhancing innate immune system functions. Potential shortcomings of these drugs include the induction of nonresponsiveness upon repeated use and the expansion of only the Vδ2 subset of human γδ T cells. Vδ1 T cells, the major tissue subset, are unaffected by phosphoantigen agonists. Using FACS-based assays, we screened primary bovine cells for novel γδ T cell agonists with activities not encompassed by the current treatments in an effort to realize the full therapeutic potential of γδ T cells. We identified γδ T cell agonists derived from the condensed tannin fractions of Uncaria tomentosa (Cat’s Claw) and Malus domestica (apple). Based on superior potency, the apple extract was selected for detailed analyses on human cells. The apple extract was a potent agonist for both human Vδ1 and Vδ2 T cells and NK cells. Additionally, the extract greatly enhanced phosphoantigen-induced γδ T cell expansion. Our analyses suggest that a tannin-based drug may complement the phosphoantigen-based drugs, thereby enhancing the therapeutic potential of γδ T cells.

To elucidate the functions of circulating gammadelta T cells, in the absence of antigen stimulation, the differential gene expression of two circulating gammadelta T cell subsets was analyzed. The two subsets, with distinct trafficking phenotypes in young calves, were GD3.5(+), CD8(-), WC1(+) or GD3.5(-), CD2(+), WC1(-), and 90-100% CD8(+) and were sorted based on GD3.5 and gammadelta T cell receptor expression. Results from two different human arrays probed with cDNA from these gammadelta T cell subsets indicated that they have markedly different tissue-specific functions. The genes preferentially expressed by GD3.5(+) (CD8(-)) gammadelta T cells demonstrated that they were highly activated, proliferative, and inflammatory, whereas those expressed by GD3.5(-) (primarily CD8(+)) gammadelta T cells were involved in promoting quiescence, consistent with a role for gammadelta T cells as sentinel mucosal cells, and several were interferon-regulated genes. Gene expression and phenotypic assays indicated that CD8(+) gammadelta T cells were apoptotic, whereas CD8(-) gammadelta T cells were apoptosis-resistant. Differential expression of multiple genes was confirmed in both arrays: That of 14 genes was confirmed by quantitative reverse transcriptase-polymerase chain reaction and that of seven proteins was confirmed by flow cytometry. This novel, genomic analysis of circulating gammadelta T cell subsets, without confounding effects of the tissue microenvironment, offers new insight into the biology and development of neonatal gammadelta T cells.

Intracellular distribution of iron oxide nanoparticles incorporated within a ferritin mutant that displays genetically introduced cell‐targeted peptides (RGD‐4C) on its exterior surface are investigated using scanning transmission electron microscopy with a high‐angle annular dark‐field detector. The particles (indicated by arrows) internalized into macrophages much more effectively than those with noncell‐targeted ferritin.

Natural killer (NK) cells and dendritic cells (DCs) have been shown to link the innate and adaptive immune systems. Likewise, a new innate cell subset, interferon-producing killer DCs (IKDCs), shares phenotypic and functional characteristics with both DCs and NK cells. Here, we show IKDCs play an essential role in the resolution of experimental autoimmune encephalomyelitis (EAE) upon treatment with the tolerizing agent, myelin oligodendrocyte glycoprotein (MOG), genetically fused to reovirus protein σ1 (termed MOG-pσ1). Activated IKDCs were recruited subsequent MOG-pσ1 treatment of EAE, and disease resolution was abated upon NK1.1 cell depletion. These IKDCs were able to kill activated CD4+ T cells and mature dendritic DCs, thus, contributing to EAE remission. In addition, IKDCs were responsible for MOG-pσ1-mediated MOG-specific regulatory T cell recruitment to the CNS. The IKDCs induced by MOG-pσ1 expressed elevated levels of HVEM for interactions with cognate ligand-positive cells: LIGHT+ NK and Teff cells and BTLA+ B cells. Further characterization revealed these activated IKDCs being MHC class IIhigh, and upon their adoptive transfer (CD11c+NK1.1+MHC class IIhigh), IKDCs, but not CD11c+NK1.1+MHC class IIintermediate/low (unactivated) cells, conferred protection against EAE. These activated IKDCs showed enhanced CD107a, PD-L1, and granzyme B expression and could present OVA, unlike unactivated IKDCs. Thus, these results demonstrate the interventional potency induced HVEM+ IKDCs to resolve autoimmune disease.

To better understand the roles of γδ T cells in mucosal infection, we utilized Salmonella enterica serovar Typhimurium (Salmonella serovar Typhimurium) infection in cattle as it closely approximates Salmonella serovar Typhimurium-induced enterocolitis in humans. Protein and gene expression in αβ and γδ T cells derived from lymphatic ducts draining the gut mucosa in Salmonella serovar Typhimurium infected calves were analyzed. In calves with enterocolitis, general gene expression trends in γδ T cells suggested subtle activation and innate response, whereas αβ T cells were relatively quiescent following Salmonella serovar Typhimurium infection. An increase in IL-2Rα expression on γδ T cells from infected calves and results from in vitro assays suggested that γδ T cells were primed by Salmonella serovar Typhimurium LPS to better respond to IL-2 and IL-15. Together with gene expression trends in vivo, these data support early priming activation of target tissue γδ T cells during Salmonella serovar Typhimurium infection.

Regulatory T cells (Tregs) induced during autoimmunity often become quiescent and unable to resolve disease, suggesting inadequate activation. Resolution of established experimental autoimmune encephalomyelitis (EAE) can be achieved with myelin oligodendrocyte glycoprotein (MOG) fused to reovirus protein σ1 (MOG-pσ1) which activates Tregs, restoring protection, but requiring other regulatory cells to revitalize them. B cells have a dichotomous role in both the pathogenesis and recovery from EAE. While inflammatory B cells contribute to EAE’s pathogenesis, treatment of EAE mice with MOG-pσ1, but not OVA-pσ1, resulted in an influx of IL-10-producing B220+CD5+ B regulatory cells (Bregs) enabling Tregs to recover their inhibitory activity, and in turn, leading to the rapid amelioration of EAE. These findings implicate direct interactions between Bregs and Tregs to facilitate this recovery. Adoptive transfer of B220+CD5− B cells from MOG-pσ1-treated EAE or Bregs from PBS-treated EAE mice did not resolve disease while the adoptive transfer of MOG-pσ1-induced B220+CD5+ Bregs greatly ameliorated EAE. MOG-pσ1-, but not OVA-pσ1-induced IL-10-producing Bregs, expressed elevated levels of BTLA relative to CD5− B cells, as opposed to Tregs or effector T (Teff) cells, whose BTLA expression was not affected. These induced Bregs restored EAE Treg function in a BTLA-dependent manner. BTLA−/− mice showed more pronounced EAE with fewer Tregs but, upon adoptive transfer of MOG-pσ1-induced BTLA+ Bregs, BTLA−/− mice were protected against EAE. Hence, this evidence shows the importance of BTLA in activating Tregs to facilitate recovery from EAE.

We have begun to elucidate the role of γδ T cells in innate immunity. Purified human and bovine γδ T cells display a subtle activation, akin to priming, in response to a wide variety of pathogen associated molecular patterns (PAMPs) such as lipopolysaccharide and peptidoglycan. A primed γδ T cell displays an enhanced response to downstream secondary signals compared to resting cells, but is not overtly activated. The signature response of a primed γδ T cell include increases in Mip1α, GM-CSF, and IL-2Rα gene and protein expression, that renders them more sensitive to IL-2. Priming is distinct from overt activation by known TCR agonists in that upregulation of IFNγ and TNFα, the signature of an activated γδ T cell, are rarely detected. Priming has also been detected in vivo in γδ, but not αβ, T cells derived from the gut mucosa of Salmonella infected calves. In an effort to manipulate γδ T cells to provide an innate protective response, we have identified compounds and herbal products that mimic the priming activation of PAMPs on γδ T cells. Treatment of bovine calves with one of the plant extracts protects against Salmonella-induced enterocolitis. γδ T cell priming may be a critical step in innate immune protection and clearance, especially for pathogens that invade mucosal surfaces, where the majority of γδ T cells are found.