Utilizing the Lung as a Model to Study Nanoparticle-Based Drug Delivery Systems

Intrapulmonary administration of purified NEIL2 abrogates NF-κB-mediated inflammation

Aberrant or constitutive activation of nuclear factor kappa B (NF-κB) contributes to various human inflammatory diseases and malignancies via the upregulation of genes involved in cell proliferation, survival, angiogenesis, inflammation, and metastasis. Thus, inhibition of NF-κB signaling has potential for therapeutic applications in cancer and inflammatory diseases. We reported previously that Nei-like DNA glycosylase 2 (NEIL2), a mammalian DNA glycosylase, is involved in the preferential repair of oxidized DNA bases from the transcriptionally active sequences via the transcription-coupled base excision repair pathway. We have further shown that Neil2-null mice are highly sensitive to tumor necrosis factor α (TNFα)- and lipopolysaccharide-induced inflammation. Both TNFα and lipopolysaccharide are potent activators of NF-κB. However, the underlying mechanism of NEIL2's role in the NF-κB-mediated inflammation remains elusive. Here, we have documented a noncanonical function of NEIL2 and demonstrated that the expression of genes, such as Cxcl1, Cxcl2, Cxcl10, Il6, and Tnfα, involved in inflammation and immune cell migration was significantly higher in both mock- and TNFα-treated Neil2-null mice compared with that in the WT mice. NEIL2 blocks NF-κB's binding to target gene promoters by directly interacting with the Rel homology region of RelA and represses proinflammatory gene expression as determined by co-immunoprecipitation, chromatin immunoprecipitation, and electrophoretic mobility-shift assays. Remarkably, intrapulmonary administration of purified NEIL2 via a noninvasive nasal route significantly abrogated binding of NF-κB to cognate DNA, leading to decreased expression of proinflammatory genes and neutrophil recruitment in Neil2-null as well as WT mouse lungs. Our findings thus highlight the potential of NEIL2 as a biologic for inflammation-associated human diseases.

Anti-ST2 Nanoparticle Alleviates Lung Inflammation by Targeting ILC2s-CD4+T Response

Background

Asthma has been regarded as an inflammatory disease, and group 2 innate lymphoid cells (ILC2s) are implicated in asthma pathogenesis. However, no strategy is available to block ILC2s function. Efficiency is also limited due to the use of systemic or subcutaneous routes of administration. The purpose of this study was to investigate the effects of nanoparticles targeting suppression of tumorigenicity 2 (ST2), which is the ILC2 receptor, to alleviate lung inflammation in the murine model of asthma.

Methods

The ultra-small SPIO nanoparticles were firstly synthesized, OVA-induced mice were administered by anti-ST2-conjugated nanoparticles. The inflammatory degree of the lung was investigated by H&E. The percentages of ILC2s and CD4⁺T cells in bronchoalveolar lavage fluid (BALF) and lung tissue were determined by FACS. Th2-cytokine and OVA-IgE levels were detected by real-time PCR and ELISA, respectively.

Results

Treatment with anti-ST2-conjugated nanoparticles significantly alleviated airway inflammation, IL-33 and IL-13 levels and the percentage of CD4⁺T cells. The percentage of ILC2s was increased, whereas the levels of IL-13 and IL-5 expressed by ILC2s were reduced.

Conclusion

In the present study, we demonstrated that anti-ST2-conjugated nanoparticles can efficiently control lung inflammation in OVA-induced mice by reducing the ability of ILC2s to produce IL-5 and IL-13, thereby reducing CD4+T cells. Our study also demonstrated that the nanoparticle delivery system could improve the performance of anti-ST2, which may be used as a strategic tool to expand the current drug market.

Pulmonary Exposure to Magnéli Phase Titanium Suboxides Results in Significant Macrophage Abnormalities and Decreased Lung Function

Coal is one of the most abundant and economic sources for global energy production. However, the burning of coal is widely recognized as a significant contributor to atmospheric particulate matter linked to deleterious respiratory impacts. Recently, we have discovered that burning coal generates large quantities of otherwise rare Magnéli phase titanium suboxides from TiO2 minerals naturally present in coal. These nanoscale Magnéli phases are biologically active without photostimulation and toxic to airway epithelial cells in vitro and to zebrafish in vivo. Here, we sought to determine the clinical and physiological impact of pulmonary exposure to Magnéli phases using mice as mammalian model organisms. Mice were exposed to the most frequently found Magnéli phases, Ti6O11, at 100 parts per million (ppm) via intratracheal administration. Local and systemic titanium concentrations, lung pathology, and changes in airway mechanics were assessed. Additional mechanistic studies were conducted with primary bone marrow derived macrophages. Our results indicate that macrophages are the cell type most impacted by exposure to these nanoscale particles. Following phagocytosis, macrophages fail to properly eliminate Magnéli phases, resulting in increased oxidative stress, mitochondrial dysfunction, and ultimately apoptosis. In the lungs, these nanoparticles become concentrated in macrophages, resulting in a feedback loop of reactive oxygen species production, cell death, and the initiation of gene expression profiles consistent with lung injury within 6 weeks of exposure. Chronic exposure and accumulation of Magnéli phases ultimately results in significantly reduced lung function impacting airway resistance, compliance, and elastance. Together, these studies demonstrate that Magnéli phases are toxic in the mammalian airway and are likely a significant nanoscale environmental pollutant, especially in geographic regions where coal combustion is a major contributor to atmospheric particulate matter.