Mycobacterium tuberculosis protein Rv2220 induces maturation and activation of dendritic cells.

Tuberculosis remains a serious health problem worldwide. Characterization of the dendritic cell (DC)-activating mycobacterial proteins has driven the development of effective TB vaccine candidates besides improving the understanding of immune responses. Some studies have emphasized the essential role of protein Rv2220 from M. tuberculosis in mycobacterial growth. Nonetheless, little is known about cellular immune responses to Rv2220. In this study, our aim was to test whether protein Rv2220 induces maturation and activation of DCs. Rv2220-activated DCs appeared to be in a mature state with elevated expression of relevant surface molecules and proinflammatory cytokines. DC maturation caused by Rv2220 was mediated by MAPK and NF-κB signaling pathways. Specifically, Rv2220-matured DCs induced the expansion of memory CD62LlowCD44highCD4+ T cells in the spleen of mycobacteria-infected mice. Our results suggest that Rv2220 regulates host immune responses through maturation of DCs, a finding that points to a new vaccine candidate against tuberculosis.

Solubilized curcuminoid complex prevents extensive immunosuppression through immune restoration and antioxidant activity: Therapeutic potential against SARS-CoV-2 (COVID-19).

The therapeutic benefits of curcuminoids in various diseases have been extensively reported. However, little is known regarding their preventive effects on extensive immunosuppression. We investigated the immunoregulatory effects of a curcuminoid complex (CS/M), solubilized with stevioside, using a microwave-assisted method in a cyclophosphamide (CTX)-induced immunosuppressive mouse model and identified its new pharmacological benefits. CTX-treated mice showed a decreased number of innate cells, such as dendritic cells (DCs), neutrophils, and natural killer (NK) cells, and adaptive immune cells (CD4 and CD8 T cells) in the spleen. In addition, CTX administration decreased T cell activation, especially that of Th1 and CD8 T cells, whereas it increased Th2 and regulatory T (Treg) cell activations. Pre-exposure of CS/M to CTX-induced immunosuppressed mice restored the number of innate cells (DCs, neutrophils, and NK cells) and increased their activity (including the activity of macrophages). Exposure to CS/M also led to the superior restoration of T cell numbers, including Th1, activated CD8 T cells, and multifunctional T cells, suppressed by CTX, along with a decrease in Th2 and Treg cells. Furthermore,CTX-injected mice pre-exposed to CS/M were accompanied by an increase in the levels of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), which play an essential role against oxidative stress. Importantly, CS/M treatment significantly reduced viral loads in severe acute respiratory syndrome coronavirus2-infected hamsters and attenuated the gross pathology in the lungs. These results provide new insights into the immunological properties of CS/M in preventing extensive immunosuppression and offer new therapeutic opportunities against various cancers and infectious diseases caused by viruses and intracellular bacteria.

Mycobacterium tuberculosis Rv2005c Induces Dendritic Cell Maturation and Th1 Responses and Exhibits Immunotherapeutic Activity by Fusion with the Rv2882c Protein.

Immunotherapy represents a promising approach for improving current antibiotic treatments through the engagement of the host's immune system. Latency-associated antigens have been included as components of multistage subunit tuberculosis vaccines. We first identified Rv2005c, a DosR regulon-encoded protein, as a seroreactive protein. In this study, we found that Rv2005c induced dendritic cell (DC) maturation and Th1 responses, and its expression by Mycobacterium tuberculosis (Mtb) within macrophages was enhanced by treatment with CoCl2, a hypoxia-mimetic agent. T cells activated by Rv2005c-matured DCs induced antimycobacterial activity in macrophages under hypoxic conditions but not under normoxic conditions. However, Rv2005c alone did not exhibit any significant vaccine efficacy in our mouse model. The fusion of Rv2005c to the macrophage-activating protein Rv2882c resulted in significant activation of DCs and antimycobacterial activity in macrophages, which were enhanced under hypoxic conditions. Furthermore, the Rv2882c-Rv2005c fusion protein showed significant adjunctive immunotherapeutic effects and led to the generation of long-lasting, antigen-specific, multifunctional CD4+ T cells that coproduced TNF-α, IFN-γ and IL-2 in the lungs of our established mouse model. Overall, these results provide a novel fusion protein with immunotherapeutic potential as adjunctive chemotherapy for tuberculosis.

Influence of temperature shifts on the onset and development of red sea bream iridoviral disease in rock bream Oplegnathus fasciatus.

The effects of various water temperature treatments on the development of red sea bream iridovirus disease (RSIVD) in rock bream Oplegnathus fasciatus challenged with iridovirus Sachun (IVS-1) were determined by measuring the mortality and the viral concentration in the spleen of infected fish. Experimental infections of rock bream with IVS-1 at water temperatures of 18, 21, and 25 degrees C resulted in a cumulative mortality of 100%, but infections at 13 degrees C resulted in 0% mortality, even after 45 d. The disease progressed more rapidly at higher water temperatures; at 25, 21, and 18 degrees C, the mean numbers of days until death were 17, 20, and 30 d, respectively. When the water temperature for fish infected with iridovirus by intramuscular injection was shifted from 13 to 25 degrees C, the cumulative mortality reached 100%, with rapid onset of the disease, independent of the time at which the temperature was shifted, i.e. 7, 14, or 30 d after injection at 13 degrees C. Real-time PCR data revealed that the viral genome copy number in the spleen of rock bream maintained at 13 degrees C increased with time, suggesting the occurrence of viral replication even at 13 degrees C. In the reverse experiment, when the water temperature for fish that were infected at a higher temperature was shifted to 13 degrees C, 3 or 7 d after injection at 25 degrees C, the fish showed 100% cumulative mortality, although the mean number of days until death was higher than that observed for fish maintained at a constant temperature of 25 degrees C. The viral DNA concentration in the spleen of rock bream that had been shifted down to 13 degrees C, 3 or 7 d after injection at 25 degrees C, was not suppressed, but increased and eventually reached levels sufficient to induce mortality at 13 degrees C. However, the level of viral genome copy numbers in the spleen of dead fish at 25 degrees C, regardless of whether those fish were held at a constant temperature of 25 degrees C or shifted up from 13 degrees C, appeared to be greater than the level found in the dead fish shifted down to 13 degrees C after inoculation at 25 degrees C.

Cell wall skeleton of Mycobacterium bovis BCG enhances the vaccine potential of antigen 85B against tuberculosis by inducing Th1 and Th17 responses.

A safe and effective adjuvant is necessary to induce reliable protective efficacy of the protein-based vaccines against tuberculosis (TB). Mycobacterial components, such as synthetic cord factor and arabinogalactan, have been used as one of the adjuvant components. Mycobacterium bovis bacillus Calmette- Guérin cell-wall skeleton (BCG-CWS) has been used as an effective immune-stimulator. However, it is not proven whether BCG-CWS can be an effective adjuvant for the subunit protein vaccine of TB. In this study, we demonstrated that the BCG-CWS effectively coupled with Ag85B and enhanced the conjugated Ag85B activity on the maturation of dendritic cells (DCs). Ag85B-BCG-CWS-matured DCs induced significant Th1 and Th17 responses when compared to BCG-CWS or Ag85B alone. In addition, significant Ag85B-specific Th1 and Th17 responses were induced in Ag85B-BCG-CWS-immunized mice before infection with M. tuberculosis and maintained after infection. Moreover, Ag85B-BCG-CWS showed significant protective effect comparable to live BCG at 6 weeks after infection and maintained its protective efficacy at 32 weeks post-challenge, whereas live BCG did not. These results suggest that the BCG-CWS may be an effective adjuvant candidate for a protein-based vaccine against TB.

Mycobacterium tuberculosis Rv3463 induces mycobactericidal activity in macrophages by enhancing phagolysosomal fusion and exhibits therapeutic potential.

Macrophages are responsible for innate and adaptive immune response activation necessary for eliminating infections. Optimal activation of macrophages to phagocytize Mycobacterium tuberculosis is critical in anti-mycobacterial defense. Here, we identified a novel Rv3463 hypothetical protein that induces macrophage activation in Mtb culture filtrate. Recombinant Rv3463 activated mouse bone marrow-derived macrophages to induce the expression of surface molecules and secrete pro-inflammatory cytokines via the TLR2 and TLR4 pathways. Mitogen activated protein kinase, phospatidylinositol-4,5-bisphosphate 3-kinases, and the NF-κB signaling pathways are involved in Rv3463-mediated macrophage activation. Furthermore, Rv3463 induced bactericidal effects in Mtb-infected macrophages through phagosome maturation and phagolysosomal fusion enhanced by phospatidylinositol-4,5-bisphosphate 3-kinases and Ca2+ signaling pathways and exhibited therapeutic effects in a short-term Mtb-infection mouse model. Overexpression of Rv3463 in M. smegmatis caused rapid clearance of bacteria in macrophages and mice. Our study suggests that Rv3463 is a promising target for the development of post-exposure tuberculosis vaccines or adjunct immune-therapy.

Mycobacterium tuberculosis Protein Rv3841 Activates Dendritic Cells and Contributes to a T Helper 1 Immune Response.

The attenuated vaccine Mycobacterium bovis BCG (Bacille Calmette Guerin) has limited protective efficacy against TB. The development of more effective TB vaccines has focused on the mycobacterial antigens that cause strong T helper 1 (Th1) responses. Mtb protein Rv3841 (bacterioferritin B; BfrB) is known to play a crucial role in the growth of Mtb. Nonetheless, it is unclear whether Rv3841 can induce protective immunity against Mtb. Here, we studied the action of Rv3841 in maturation of dendritic cells (DCs) and its engagement in the development of T-cell immunity. We found that Rv3841 functionally activated DCs by upregulating costimulatory molecules and increased secretion of proinflammatory cytokines. Activation of DCs by Rv3841 was mediated by Toll-like receptor 4 (TLR4), followed by triggering of mitogen-activated protein kinase and nuclear factor-κB signaling pathways. In addition, Rv3841-matured DCs effectively proliferated and polarized Th1 immune response of naïve CD4+ and CD8+ T-cells. Moreover, Rv3841 specifically caused the expansion of CD4+CD44highCD62Llow T-cells from Mtb-infected mice; besides, the T-cells activated by Rv3841-matured DCs inhibited intracellular mycobacterial growth. Our data suggest that Rv3841 induces DC maturation and protective immune responses, a finding that may provide candidate of effective TB vaccines.