Yurong Cai

Background/Objectives: Mycobacterium tuberculosis is the causative agent of tuberculosis and the leading cause of death from a single infection with the microorganism. Tuberculosis remains globally one of the major diseases leading to high mortality rates, with serious implications for public health and economic development. Therefore, tuberculosis prevention and control is crucial for global health and socio-economic stability. The development of effective preventive vaccines remains an urgent task in the fight against tuberculosis. Methods: The Mycobacterium tuberculosis antigen PPE18 was fused to Zera, and Bacmid was extracted and transfected into Sf9, which was purified and characterized for the formation of nanoparticle protein bodies. BALB/c mice and calves were immunized, and the immunogenicity of the nanoparticle vaccine was assessed by serum antibodies and splenic lymphocytes. Results: Zera-71CA-mCherry can be expressed in Sf9 cells, forming 0.5–1.2 μm protein bodies. Excising the mCherry sequence, Zera-71CA/Zera-PPE18 candidate nanoparticle-immunized mice were able to elicit serum antibody levels and the proliferation of splenic lymphocytes, and immunized calves were determined to have high levels of serum antibody levels, and IFN-γ and TNF-α levels. Conclusions: The results indicated that Zera-71CA/Zera-PPE18 recombinant nanoparticles had good immunogenicity as a subunit vaccine in both BALB/c mice and calves and are potential candidates for further development as effective subunit vaccines.

Viral muscle soreness (VMS) is a common feature during acute viral infections, including those caused by enteroviruses, and it substantially diminishes patients’ quality of life. At present, we aim to establish the “brain-muscle” axis to explore the underlying mechanisms of VMS. We initially observed that diminished pain threshold occurred in enterovirus A71 (EV-A71)–infected C57BL/6J and AG6 mice. Subsequently, RNA sequencing data showed that lipocalin 2 (LCN2) was up-regulated during multiple viral infections, including EV-A71, Japanese encephalitis virus, vesicular stomatitis virus, and West Nile virus, which all caused VMS. As expected, Lcn2 -deficient C57BL/6 J ( Lcn2 ^−/− ) mice exhibited greater pain tolerance, as shown by stronger grip force and stable motor function after EV-A71 infection. Mechanistically, EV-A71–induced high-mobility group 1 (HMGB1) stimulated astrocyte-derived LCN2 secreted into the circulatory system, which enhanced glycolysis and induced lactate buildup in muscle through increasing pyruvate dehydrogenase kinase 1 (PDK1) expression and decreasing pyruvate dehydrogenase (PDH) activity. Together, HMGB1/LCN2/PDK1/lactate pathway in the brain-muscle axis promoted VMS development.

Innate immune cells have been acknowledged as trainable in recent years. While intestinal tuft cells are recognized for their crucial roles in the host defense against intestinal pathogens, there remains uncertainty regarding their trainability. Enterovirus 71 (EV71), a prevalent enterovirus that primarily infects children but rarely infects adults. At present, there is a significant expansion of intestinal tuft cells in the EV71-infected mouse model, which is associated with EV71-induced interleukin-25 (IL-25) production. Further, we found that IL-25 pre-treatment at 2 weeks old mouse enabled tuft cells to acquire immune memory. This was evidenced by the rapid expansion and stronger response of IL-25-trained tuft cells in response to EV71 infection at 6 weeks old, surpassing the reactivity of naïve tuft cells in mice without IL-25-trained progress. Interestingly, IL-25-trained intestinal tuft cells exhibit anti-enteroviral effect via producing a higher level of IL-25. Mechanically, IL-25 treatment upregulates spermidine/spermine acetyl-transferase enzyme (SAT1) expression, mediates intracellular polyamine deficiency, further inhibits enterovirus replication. In summary, tuft cells can be trained by IL-25, which supports faster and higher level IL-25 production in response to EV71 infection and further exhibits anti-enteroviral effect via SAT1-mediated intracellular polyamine deficiency. Given that IL-25 can be induced by multiple gut microbes during human growth and development, including shifts in gut flora abundance, which may partially explain the different susceptibility to enteroviral infections between adults and children.

Intestinal tuft cells, a kind of epithelial immune cells, rapidly expand in response to pathogenic infections, which is associated with infection‐induced interleukin 25 (IL‐25) upregulation. However, the metabolic mechanism of IL‐25‐induced tuft cell expansion is largely unknown. Folate metabolism provides essential purine and methyl substrates for cell proliferation and differentiation. Thus, we aim to investigate the roles of folate metabolism playing in IL‐25‐induced tuft cell expansion by enteroviral infection and recombinant murine IL‐25 (rmIL‐25) protein‐stimulated mouse models. At present, enteroviruses, such as EV71, CVA16, CVB3, and CVB4, upregulated IL‐25 expression and induced tuft cell expansion in the intestinal tissues of mice. However, EV71 did not induce intestinal tuft cell expansion in IL‐25 ^−/− mice. Interestingly, compared to the mock group, folate was enriched in the intestinal tissues of both the EV71‐infected group and the rmIL‐25 protein‐stimulated group. Moreover, folate metabolism supported IL‐25‐induced tuft cell expansion since both folate‐depletion and anti‐folate MTX‐treated mice had a disrupted tuft cell expansion in response to rmIL‐25 protein stimulation. In summary, our data suggested that folate metabolism supported intestinal tuft cell expansion in response to enterovirus‐induced IL‐25 expression, which provided a new insight into the mechanisms of tuft cell expansion from the perspective of folate metabolism.

Bovine tuberculosis, caused by both MTB(Mycobacterium tuberculosis) and MB(Mycobacterium bovis), is one of the most serious zoonotic diseases in the world. Both pathogenic MTB and MB interact closely with the host alveolar macrophages. However, the mechanisms of defense response of macrophages to MTB or MB still need further researches. Presently, in-depth comparative proteome analysis was performed on the MB- and MTB- infected macrophage. We identified that macrophages was more sensitive to the MB infection. Both pathogens could induce strong energy metabolism of macrophages. To eliminate MB and protect the host, a bunch of proteins and signaling which involved in autophagy- and inflammatory-related progresses were highly activated in macrophages following MB infection. In contrast, only proteins relevant to energy metabolisms were highly expressed in macrophages following MTB infection. In summary, we proposed that macrophages were more sensitive to MB attacks and could deployed proteins functioned in autophagy- and inflammatory-related progresses to protect the host. Our research provide a novel insight into the different mechanisms of defense responses of macrophages to both MTB and MB infection.