Vaccine Potential of Mycobacterial Antigens against Asthma

Tuberculosis research advances and future trends: A bibliometric knowledge mapping approach

The Gulf Cooperation Council (GCC) countries are more vulnerable to many transmissible diseases, including tuberculosis (TB). This study is to identify the scientific publications related to TB in the GCC countries using topic modeling and co-word analysis. A bibliometric analytic study. The R-package, VOSviewer software, IBM SPPS, and Scopus Analytics were used to analyze performance, hotspots, knowledge structure, thematic evolution, trend topics, and inter-gulf and international cooperation on TB in the past 30 years (1993-2022). A total of 1999 publications associated with research on GCC-TB were published. The annual growth rate of documents was 7.76%. Saudi Arabia is the most highly published, followed by the United Arab Emirates, Kuwait, Qatar, Oman, and Bahrain. The most-cited GC country is Kingdom Saudi Arabia, followed by Kuwait. One hundred sixty research institutions contributed to the dissemination of TB-related knowledge in the GCC, where the highest publishing organizations were King Saud University (Kingdom Saudi Arabia; n = 518). The number of publications related to TB is high in GCC Countries. The current tendencies indicated that GCC scholars are increasingly focused on deep learning, chest X-ray, molecular docking, comorbid covid-19, risk factors, and Mycobacterium bovis.

Chemical and Biological Characterization of Mycobacterium Tuberculosis-Specific ESAT6-Like Proteins and their Potentials in the Prevention of Tuberculosis and Asthma

Early Secreted Antigenic Target 6 kDa (ESAT6) is a potent immunogenic protein secreted by the bacteria causing tuberculosis, i.e., Mycobacterium tuberculosis. Another highly immunogenic culture filtrate protein whose gene is linked to ESAT6/ESXA is known as CFP10/ESXB. Because of their high immunogenicity and specificity to M. tuberculosis, these proteins have been proposed as a vaccine to prevent tuberculosis and diagnose the active/latent disease. However, the same proteins cannot be used for prevention and diagnosis because immunized but healthy people will also show a positive response and be falsely reported as diseased. Therefore, in this review article, the search was made to identify if any other ESAT6-like proteins exist in the M. tuberculosis genome. The search identified 21 additional ESAT-like proteins, i.e., ESXC to ESXW. Immunological characterization has shown that some of them (especially ESXV) were able to induce immune responses in vitro with cells obtained from tuberculosis patients and healthy donors. When the protein ESXV was tested in different recombinant forms (expressed in Escherichia coli, mycobacterial vectors, and DNA plasmids) and injected in mice, immune responses were induced to multiple epitopes of the protein. Furthermore, immunization of mice with ESXV protected them from infection with M. tuberculosis. The same protein was also able to protect mice against the induction of asthma. These results suggest that ESXV has the potential to protect against two major diseases of the world, i.e., tuberculosis and asthma, and hence may be used as a common vaccine for both diseases.

Melatonin antagonizes ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway

Over the past few years, ozone has been identified as a potential risk factor for exacerbating asthma. However, few attempts have been made to prevent the progression of ozone-exacerbated asthma. This study investigated the attenuating effects of melatonin on ozone-aggravated allergic asthma, and explored the changes to the transient receptor potential vanilloid 1 (TRPV1)-nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway associated with melatonin treatment. The levels of TRPV1 and calcitonin gene-related peptides (CGRP) in lung tissue were detected by immunohistochemistry, western blot, and enzyme-linked immunosorbent assay (ELISA). The Nrf2 signaling involved proteins and mRNA were evaluated by western blot and RT-qPCR. The change of Immunoglobulin E (IgE) and T helper (Th) 2 and Th17 cytokines in serum and bronchoalveolar lavage fluid (BALF) was determined by ELISA. Recruitment of inflammatory cells in BALF, histopathological changes, and airway hyperresponsiveness (AHR) were also determined in lung tissues. Our results indicated that melatonin treatment significantly reduced oxidative stress, as indicated by levels of glutathione (GSH), malonaldehyde (MDA), and 8-hydroxy-2-deoxyguanosine (8-OH-dG). Moreover, ozone-exacerbated asthma symptoms, such as inflammatory cell infiltration, levels of serum immunoglobulin, Th2 and Th17 cytokines in BALF, obvious changes in lung histology, and AHR, were all ameliorated by melatonin treatment. Interestingly, melatonin not only markedly decreased the protein levels of TRPV1 and CGRP, but also enhanced the expression of Nrf2, quinone oxidoreductase-1 (NQO-1), and heme oxygenase-1 (HO-1). Taken together, our results demonstrate that melatonin administration could antagonize ozone-exacerbated asthma by inhibiting the TRPV1 channel and stabilizing the Nrf2 pathway.

Adjuvants and Antigen-Delivery Systems for Subunit Vaccines against Tuberculosis

The only licensed vaccine against tuberculosis is BCG. However, BCG has failed to provide consistent protection against tuberculosis, especially pulmonary disease in adults. Furthermore, the use of BCG is contraindicated in immunocompromised subjects. The research towards the development of new vaccines against TB includes the use of Mycobacterium tuberculosis antigens as subunit vaccines. Such vaccines may be used either alone or in the prime-boost model in BCG-vaccinated people. However, the antigens for subunit vaccines require adjuvants and/or delivery systems to induce appropriate and protective immune responses against tuberculosis and other diseases. Articles published in this Special Issue have studied the pathogenesis of BCG in children and the use of BCG and recombinant BCG as potential vaccines against asthma. Furthermore, the use of different adjuvants and delivery systems in inducing the protective immune responses after immunization with subunit vaccines has been described.

An Overview of the Development of New Vaccines for Tuberculosis

Currently, there is only one licensed vaccine against tuberculosis (TB), the Bacillus Calmette–Guérin (BCG). Despite its protective efficacy against TB in children, BCG has failed to protect adults against pulmonary TB, lacks therapeutic value, and causes complications in immunocompromised individuals. Furthermore, it compromises the use of antigens present in the purified protein derivate of Mycobacterium tuberculosis in the diagnosis of TB. Many approaches, e.g., whole-cell organisms, subunit, and recombinant vaccines are currently being explored for safer and more efficacious TB vaccines than BCG. These approaches have been successful in developing a large number of vaccine candidates included in the TB vaccine pipeline and are at different stages of clinical trials in humans. This paper discusses current vaccination strategies, provides directions for the possible routes towards the development of new TB vaccines and highlights recent findings. The efforts for improved TB vaccines may lead to new licensed vaccines capable of replacing/supplementing BCG and conferring therapeutic value in patients with active/latent TB.