Engineered Nanomaterials for Immunomodulation: A Review.

The immune system usually provides a defense against invading pathogenic microorganisms and any other particulate contaminants. Nonetheless, it has been recently reported that nanomaterials can evade the immune system and modulate immunological responses due to their unique physicochemical characteristics. Consequently, nanomaterial-based activation of immune components, i.e., neutrophils, macrophages, and other effector cells, may induce inflammation and alter the immune response. Here, it is essential to distinguish the acute and chronic modulations triggered by nanomaterials to determine the possible risks to human health. Nanomaterials size, shape, composition, surface charge, and deformability are factors controlling their uptake by immune cells and the resulting immune responses. The exterior corona of molecules adsorbed over nanomaterials surfaces also influences their immunological effects. Here, we review current nanoengineering trends for targeted immunomodulation with an emphasis on the design, safety, and potential toxicity of nanomaterials. First, we describe the characteristics of engineered nanomaterials that trigger immune responses. Then, the biocompatibility and immunotoxicity of nanoengineered particles are debated, because these factors influence applications. Finally, future nanomaterial developments in terms of surface modifications, synergistic approaches, and biomimetics are discussed.

Bacterial immunotherapy: is it a weapon in our arsenal in the fight against cancer?

Advances in understanding the genetic basis of cancer have driven alternative treatment approaches. Recent findings have demonstrated the potential of bacteria and it's components to serve as robust theranostic agents for cancer eradication. Compared to traditional cancer therapies like surgery, chemotherapy, radiotherapy, bacteria mediated tumor therapy has exhibited superior cancer suppressing property which is attributed a lot to it's tumor proliferating and accumulating characteristics. Genetically modified bacteria has reduced inherent toxicity and enhanced specificity towards tumor microenvironment. This anti- tumor activity of bacteria is attributed to its toxins and other active components from the cell membrane, cell wall and spores. Furthermore, bacterial genes can be regulated to express and deliver cytokines, antibodies and cancer therapeutics. Although there is less clinical data available, the pre- clinical research clearly indicates the feasibility and potential of bacteria- mediated cancer therapy.

MPYS Modulates Fatty Acid Metabolism and Immune Tolerance at Homeostasis Independent of Type I IFNs.

MPYS/STING (stimulator of IFN genes) senses cyclic dinucleotides (CDNs), generates type I IFNs, and plays a critical role in infection, inflammation, and cancer. In this study, analyzing genotype and haplotype data from the 1000 Genomes Project, we found that the R71H-G230A-R293Q (HAQ) MPYS allele frequency increased 57-fold in East Asians compared with sub-Saharan Africans. Meanwhile, the G230A-R293Q (AQ) allele frequency decreased by 98% in East Asians compared with sub-Saharan Africans. We propose that the HAQ and AQ alleles underwent a natural selection during the out-of-Africa migration. We used mouse models of HAQ and AQ to investigate the underlying mechanism. We found that the mice carrying the AQ allele, which disappeared in East Asians, had normal CDN-type I IFN responses. Adult AQ mice, however, had less fat mass than did HAQ or wild-type mice on a chow diet. AQ epididymal adipose tissue had increased regulatory T cells and M2 macrophages with protein expression associated with enhanced fatty acid oxidation. Conditional knockout mice and adoptive cell transfer indicate a macrophage and regulatory T cell-intrinsic role of MPYS in fatty acid metabolism. Mechanistically, AQ/IFNAR1-/- mice had a similar lean phenotype as for the AQ mice. MPYS intrinsic tryptophan fluorescence revealed that the R71H change increased MPYS hydrophilicity. Lastly, we found that the second transmembrane (TM) and the TM2-TM3 linker region of MPYS interact with activated fatty acid, fatty acyl-CoA. In summary, studying the evolution of the human MPYS gene revealed an MPYS function in modulating fatty acid metabolism that may be critical during the out-of-Africa migration.

In vivo reprogramming of pathogenic lung TNFR2+ cDC2s by IFNß inhibits HDM-induced asthma.

Asthma is a common inflammatory lung disease with no known cure. Previously, we uncovered a lung TNFR2+ conventional DC2 subset (cDC2s) that induces regulatory T cells (Tregs) maintaining lung tolerance at steady state but promotes TH2 response during house dust mite (HDM)-induced asthma. Lung IFNß is essential for TNFR2+ cDC2s-mediated lung tolerance. Here, we showed that exogenous IFNß reprogrammed TH2-promoting pathogenic TNFR2+ cDC2s back to tolerogenic DCs, alleviating eosinophilic asthma and preventing asthma exacerbation. Mechanistically, inhaled IFNß, not IFNα, activated ERK2 signaling in pathogenic lung TNFR2+ cDC2s, leading to enhanced fatty acid oxidation (FAO) and lung Treg induction. Last, human IFNß reprogrammed pathogenic human lung TNFR2+ cDC2s from patients with emphysema ex vivo. Thus, we identified an IFNß-specific ERK2-FAO pathway that might be harnessed for DC therapy.

Monocyte-Derived Dendritic Cells (moDCs) Differentiate into Bcl6+ Mature moDCs to Promote Cyclic di-GMP Vaccine Adjuvant-Induced Memory TH Cells in the Lung.

Induction of lung mucosal immune responses is highly desirable for vaccines against respiratory infections. We recently showed that monocyte-derived dendritic cells (moDCs) are responsible for lung IgA induction. However, the dendritic cell subset inducing lung memory TH cells is unknown. In this study, using conditional knockout mice and adoptive cell transfer, we found that moDCs are essential for lung mucosal responses but are dispensable for systemic vaccine responses. Next, we showed that mucosal adjuvant cyclic di-GMP differentiated lung moDCs into Bcl6+ mature moDCs promoting lung memory TH cells, but they are dispensable for lung IgA production. Mechanistically, soluble TNF mediates the induction of lung Bcl6+ moDCs. Our study reveals the functional heterogeneity of lung moDCs during vaccination and paves the way for an moDC-targeting vaccine strategy to enhance immune responses on lung mucosa.

The Third Man: DNA sensing as espionage in pulmonary vascular health and disease.

For as long as nucleic acids have been utilized to vertically and horizontally transfer genetic material, living organisms have had to develop methods of recognizing cytosolic DNA as either pathogenic (microbial invasion) or physiologic (mitosis and cellular proliferation). Derangement in key signaling molecules involved in these pathways of DNA sensing result in a family of diseases labeled interferonopathies. An interferonopathy, characterized by constitutive expression of type I interferons, ultimately manifests as severe autoimmune disease at a young age. Afflicted patients present with a constellation of immune-mediated conditions, including primary lung manifestations such as pulmonary fibrosis and pulmonary hypertension. The latter condition is especially interesting in light of the known role that DNA damage plays in a variety of types of inherited and induced pulmonary hypertension, with free DNA detection elevated in the circulation of affected individuals. While little is known regarding the role of cytosolic DNA sensing in development of pulmonary vascular disease, exciting new research in the related fields of immunology and oncology potentially sheds light on future areas of fruitful exploration. As such, the goal of this review is to summarize the state of the field of nucleic acid sensing, extrapolating common shared pathways that parallel our knowledge of pulmonary hypertension, in a molecular and cell-specific manner. Principles of DNA sensing related to known pulmonary injury inducing stimuli are also evaluated, in addition to potential therapeutic targets. Finally, future directions in pulmonary hypertension research and treatments will be briefly discussed.

The Age of Cyclic Dinucleotide Vaccine Adjuvants.

As prophylactic vaccine adjuvants for infectious diseases, cyclic dinucleotides (CDNs) induce safe, potent, long-lasting humoral and cellular memory responses in the systemic and mucosal compartments. As therapeutic cancer vaccine adjuvants, CDNs induce potent anti-tumor immunity, including cytotoxic T cells and NK cells activation that achieve durable regression in multiple mouse models of tumors. Clinical trials are ongoing to fulfill the promise of CDNs (ClinicalTrials.gov: NCT02675439, NCT03010176, NCT03172936, and NCT03937141). However, in October 2018, the first clinical data with Merck's CDN MK-1454 showed zero activity as a monotherapy in patients with solid tumors or lymphomas (NCT03010176). Lately, the clinical trial from Aduro's CDN ADU-S100 monotherapy was also disappointing (NCT03172936). The emerging hurdle in CDN vaccine development calls for a timely re-evaluation of our understanding on CDN vaccine adjuvants. Here, we review the status of CDN vaccine adjuvant research, including their superior adjuvant activities, in vivo mode of action, and confounding factors that affect their efficacy in humans. Lastly, we discuss the strategies to overcome the hurdle and advance promising CDN adjuvants in humans.

New MoDC-Targeting TNF Fusion Proteins Enhance Cyclic Di-GMP Vaccine Adjuvanticity in Middle-Aged and Aged Mice.

Cyclic dinucleotides (CDNs) are promising vaccine adjuvants inducing balanced, potent humoral, and cellular immune responses. How aging influences CDN efficacy is unclear. We examined the vaccine efficacy of 3',5'-cyclic diguanylic acid (cyclic di-GMP, CDG), the founding member of CDNs, in 1-year-old (middle-aged) and 2-year-old (aged) C57BL/6J mice. We found that 1- and 2-year-old C57BL/6J mice are defective in CDG-induced memory T helper (Th)1 and Th17 responses and high-affinity serum immunoglobulin (Ig)G, mucosal IgA production. Next, we generated two novel tumor necrosis factor (TNF) fusion proteins that target soluble TNF (solTNF) and transmembrane TNF (tmTNF) to monocyte-derived dendritic cells (moDCs) to enhance CDG vaccine efficacy in 1- and 2-year-old mice. The moDC-targeting TNF fusion proteins restored CDG-induced memory Th1, Th17, and high-affinity IgG, IgA responses in the 1- and 2-year-old mice. Together, the data suggested that aging negatively impacts CDG vaccine adjuvanticity. MoDC-targeting TNF fusion proteins enhanced CDG adjuvanticity in the aging mice.

Crystalline and Amorphous Preparation of Aluminum Hydroxide Nanoparticles Enhances Protective Antigen Domain 4 Specific Immunogenicity and Provides Protection Against Anthrax.

INTRODUCTION: Aluminum salts, although they have been used as adjuvants in many vaccine formulations since 1926, exclusively induce a Th2-biased immune response, thereby limiting their use against intracellular pathogens like Mycobacterium tuberculosis. METHODS AND RESULTS: Herein, we synthesized amorphous and crystalline forms of aluminum hydroxide nanoparticles (AH nps) of 150-200 nm size range. Using Bacillus anthracis protective antigen domain 4 (D4) as a model antigen, we demonstrated that both amorphous and crystalline forms of AH nps displayed enhanced antigen D4 uptake by THP1 cells as compared to commercial adjuvant aluminum hydroxide gel (AH gel). In a mouse model, both amorphous and crystalline AH nps triggered an enhanced D4-specific Th2- and Th1-type immune response and conferred superior protection against anthrax spore challenge as compared to AH gel. Physicochemical characterization of crystalline and amorphous AH nps revealed stronger antigen D4 binding and release than AH gel. CONCLUSION: These results demonstrate that size and crystallinity of AH nps play important roles in mediating enhanced antigen presenting cells (APCs) activation and potentiating a strong antigen-specific immune response, and are critical parameters for the rational design of alum-based Th1-type adjuvant to induce a more balanced antigen-specific immune response.

Lung IFNAR1hi TNFR2+ cDC2 promotes lung regulatory T cells induction and maintains lung mucosal tolerance at steady state.

The lung is a naturally tolerogenic organ. Lung regulatory T cells (T-regs) control lung mucosal tolerance. Here, we identified a lung IFNAR1hiTNFR2+ conventional DC2 (iR2D2) population that induces T-regs in the lung at steady state. Using conditional knockout mice, adoptive cell transfer, receptor blocking antibodies, and TNFR2 agonist, we showed that iR2D2 is a lung microenvironment-adapted dendritic cell population whose residence depends on the constitutive TNFR2 signaling. IFNß-IFNAR1 signaling in iR2D2 is necessary and sufficient for T-regs induction in the lung. The Epcam+CD45- epithelial cells are the sole lung IFNß producer at the steady state. Surprisingly, iR2D2 is plastic. In a house dust mite model of asthma, iR2D2 generates lung TH2 responses. Last, healthy human lungs have a phenotypically similar tolerogenic iR2D2 population, which became pathogenic in lung disease patients. Our findings elucidate lung epithelial cells IFNß-iR2D2-T-regs axis in controlling lung mucosal tolerance and provide new strategies for therapeutic interventions.

A niosome formulation modulates the Th1/Th2 bias immune response in mice and also provides protection against anthrax spore challenge.

INTRODUCTION: In this study, we have investigated the immunogenicity and protective efficacy of a niosomal formulation encapsulating protective antigen (PA) and PA domain 4 (D4) of Bacillus anthracis. METHODS: Nonionic surfactant-based vesicles (NISV) + PA and NISV + D4 were prepared from span-60 and cholesterol by reverse-phase evaporation method and were evaluated for in vitro characteristics and immunological studies. RESULTS: Particle characterization using transmission electron microscopy and atomic force microscopy analysis showed that the niosomal formulation was spherical in shape. The entrapment efficiency values were calculated to be 58.5% and 44.75% for PA and D4, respectively. Confocal microscopy and flow cytometry studies showed an enhanced uptake of antigen in THP1 macrophages by niosome as compared to antigen only. An in vitro release assay showed a burst release of antigen from niosome within 24 hours followed by a gradual release for 144 hours. Immunological studies showed that both PA- and D4-encapsulated niosome elicited a robust IgG titer. Antibody isotyping and cytokine profile showed that NISV + PA and NISV + D4 enhanced both Th1 and Th2 responses in mice, suggesting a mixed Th1/Th2 response. Both NISV + PA and NISV + D4 elicited high levels of anti-inflammatory cytokine interleukin-10 with low levels of pro-inflammatory cytokine tumor necrosis factor-α, suggesting the anti-inflammatory property of niosome. Both the niosomal formulations were also able to confer protection against BA infection as compared to only PA and D4. CONCLUSION: PA and D4 encapsulated NISV formulation could modulate both the Th1 and Th2 adaptive immune system and was found to be a better prophylactic against anthrax.