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The development of vaccines has always been an essential task worldwide since vaccines are regarded as powerful weapons in protecting the global population. Although the vast majority of currently authorized human vaccinations are administered intramuscularly or subcutaneously, exploring novel routes of immunization has been a prominent area of study in recent years. This is particularly relevant in the face of pandemic diseases, such as COVID-19, where respiratory immunization offers distinct advantages, such as inducing systemic and mucosal responses to prevent viral infections in both the upper and lower respiratory tracts and also leading to higher patient compliance. However, the development of respiratory vaccines confronts challenges due to the physiological barriers of the respiratory tract, with most of these vaccines still in the research and development stage. In this review, we detail the structure of the respiratory tract and the mechanisms of mucosal immunity, as well as the obstacles to respiratory vaccination. We also examine the considerations necessary in constructing a COVID-19 respiratory vaccine, including the dosage form of the vaccines, potential excipients and mucosal adjuvants, and delivery systems and devices for respiratory vaccines. Finally, we present a comprehensive overview of the COVID-19 respiratory vaccines currently under clinical investigation. We hope this review can provide valuable insights and inspiration for the future development of respiratory vaccinations., Competing Interests: Declaration of Competing Interest There are no conflicts of interest to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)

By designing an orthogonal experiment with four factors and three levels, (Na 0.5 Bi 0.495 Nd 0.005 )TiO 3 (NBT-Nd) nanopowders were prepared using a hydrothermal method under different conditions to determine the optimum hydrothermal synthesis conditions. The synthesized NBT-Nd nanopowders were characterized using X-ray diffraction measurement, ultraviolet-visible spectra, photoluminescence spectra, and transmission electron microscopy to evaluate the orthogonal experimental conditions. The results showed that NBT-Nd powders with excellent crystalline and luminescence properties could be obtained at 160°C, with a 16 h reaction time, 8 mol·L -1 NaOH, and with 0.4489 g C 19 H 42 BrN. The optimized hydrothermal method-prepared NBT-Nd powder has a rather pure rhombohedral perovskite structure at room temperature, and exhibits an aggregated polycrystalline structure containing nanotubes and nano-sized particles. Under excitation of 247 nm light, strong fluorescence emissions are excited at 423 nm and 441 nm in the NBT-Nd powder that were generated by transitions of Nd 3+ from 2 D 5/2 to 4 I 9/2 and from 4 G 11/2 to 4 I 9/2 , respectively. Through CIE1931 chromaticity calculation of the emission peaks, the NBT-Nd powder was shown to emit indigo blue fluorescent light., (© 2021 John Wiley & Sons, Ltd.)

In animal models of experimental cerebral malaria (ECM), neuropathology is associated with an overwhelming inflammatory response and sequestration of leukocytes and parasite-infected RBCs in the brain. In this study, we explored the effect of vitamin D (VD; cholecalciferol) treatment on host immunity and outcome of ECM in C57BL/6 mice during Plasmodium berghei ANKA (PbA) infection. We observed that oral administration of VD both before and after PbA infection completely protected mice from ECM. VD administration significantly dampened the inducible systemic inflammatory responses with reduced circulating cytokines IFN-γ and TNF and decreased expression of these cytokines by the spleen cells. Meanwhile, VD also resulted in decreased expression of the chemokines CXCL9 and CXCL10 and cytoadhesion molecules (ICAM-1, VCAM-1, and CD36) in the brain, leading to reduced accumulation of pathogenic T cells in the brain and ultimately substantial improvement of the blood-brain barriers of PbA-infected mice. In addition, VD inhibited the differentiation, activation, and maturation of splenic dendritic cells. Meanwhile, regulatory T cells and IL-10 expression levels were upregulated upon VD treatment. These data collectively demonstrated the suppressive function of VD on host inflammatory responses, which provides significant survival benefits in the murine ECM model., (Copyright © 2014 by The American Association of Immunologists, Inc.)