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Stimulation through CD40 and TLR-4 Is an Effective Host Directed Therapy against Mycobacterium tuberculosis

View Article: PubMed Central - PubMed

ABSTRACT

Tuberculosis (TB) is the leading cause of morbidity and mortality among all infectious diseases. Failure of Bacillus Calmette Guerin as a vaccine and serious side-effects and toxicity due to long-term TB drug regime are the major hurdles associated with TB control. The problem is further compounded by the emergence of drug-resistance strains of Mycobacterium tuberculosis (Mtb). Consequently, it demands a serious attempt to explore safer and superior treatment approaches. Recently, an improved understanding of host–pathogen interaction has opened up new avenues for immunotherapy for treating TB. Although, dendritic cells (DCs) show a profound role in generating immunity against Mtb, their immunotherapeutic potential needs to be precisely investigated in controlling TB. Here, we have devised an approach of bolstering DCs efficacy against Mtb by delivering signals through CD40 and TLR-4 molecules. We found that DCs triggered through CD40 and TLR-4 showed increased secretion of IL-12, IL-6, and TNF-α. It also augmented autophagy. Interestingly, CD40 and TLR-4 stimulation along with the suboptimal dose of anti-TB drugs significantly fortified their efficacy to kill Mtb. Importantly, animals treated with the agonists of CD40 and TLR-4 boosted Th1 and Th17 immunity. Furthermore, it amplified the pool of memory CD4 T cells as well as CD8 T cells. Furthermore, substantial reduction in the bacterial burden in the lungs was observed. Notably, this adjunct therapy employing immunomodulators and chemotherapy can reinvigorate host immunity suppressed due to drugs and Mtb. Moreover, it would strengthen the potency of drugs in curing TB.

No MeSH data available.


Signaling delivered through C40.T4 potentiate DCs ability to restrict Mtb growth. DCs were infected with mycobacterial strains H37Ra, H37Rv, and M. smegmatis followed by stimulation through C40.T4 for 24 h. Later, mycobacterial survival was enumerated by CFUs plating for (A) H37Rv on 21 days; (B) H37Ra on 21 days; (C)M. smegmatis on 3 days. Data are represented as the mean ± SD of three independent experiments. “*” indicate p < 0.05.
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Figure 3: Signaling delivered through C40.T4 potentiate DCs ability to restrict Mtb growth. DCs were infected with mycobacterial strains H37Ra, H37Rv, and M. smegmatis followed by stimulation through C40.T4 for 24 h. Later, mycobacterial survival was enumerated by CFUs plating for (A) H37Rv on 21 days; (B) H37Ra on 21 days; (C)M. smegmatis on 3 days. Data are represented as the mean ± SD of three independent experiments. “*” indicate p < 0.05.

Mentions: Next, we were interested to study the effect of C40.T4 on the bactericidal activity of DCs. Mtb-infected DCs were triggered through C40.T4 for 24 h. We observed enhanced bactericidal activity of C40.T4 stimulated DCs, as evidenced by significant killing of virulent strain (H37Rv) of Mtb (p < 0.05). These results were further substantiated using non-virulent strains of mycobacteria, such as H37Ra (p < 0.05) and M. smegmatis (p < 0.05) (Figures 3A–C). Not much change was observed in CD40 or TLR-4 or isotype-matched controls. Similar results were observed in the case of macrophages (Figure S2C in Supplementary Material). It is important to mention that the difference in uptake of Mtb as shown in (Figure 2C) had no impact on their bactericidal activity. In the case of phagocytic assay, DCs were first stimulated with C40.T4 and then infected with Mtb. By contrast, bactericidal activity of DCs was demonstrated by first infecting them with Mtb and then stimulating through C40.T4.


Stimulation through CD40 and TLR-4 Is an Effective Host Directed Therapy against Mycobacterium tuberculosis
Signaling delivered through C40.T4 potentiate DCs ability to restrict Mtb growth. DCs were infected with mycobacterial strains H37Ra, H37Rv, and M. smegmatis followed by stimulation through C40.T4 for 24 h. Later, mycobacterial survival was enumerated by CFUs plating for (A) H37Rv on 21 days; (B) H37Ra on 21 days; (C)M. smegmatis on 3 days. Data are represented as the mean ± SD of three independent experiments. “*” indicate p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037235&req=5

Figure 3: Signaling delivered through C40.T4 potentiate DCs ability to restrict Mtb growth. DCs were infected with mycobacterial strains H37Ra, H37Rv, and M. smegmatis followed by stimulation through C40.T4 for 24 h. Later, mycobacterial survival was enumerated by CFUs plating for (A) H37Rv on 21 days; (B) H37Ra on 21 days; (C)M. smegmatis on 3 days. Data are represented as the mean ± SD of three independent experiments. “*” indicate p < 0.05.
Mentions: Next, we were interested to study the effect of C40.T4 on the bactericidal activity of DCs. Mtb-infected DCs were triggered through C40.T4 for 24 h. We observed enhanced bactericidal activity of C40.T4 stimulated DCs, as evidenced by significant killing of virulent strain (H37Rv) of Mtb (p < 0.05). These results were further substantiated using non-virulent strains of mycobacteria, such as H37Ra (p < 0.05) and M. smegmatis (p < 0.05) (Figures 3A–C). Not much change was observed in CD40 or TLR-4 or isotype-matched controls. Similar results were observed in the case of macrophages (Figure S2C in Supplementary Material). It is important to mention that the difference in uptake of Mtb as shown in (Figure 2C) had no impact on their bactericidal activity. In the case of phagocytic assay, DCs were first stimulated with C40.T4 and then infected with Mtb. By contrast, bactericidal activity of DCs was demonstrated by first infecting them with Mtb and then stimulating through C40.T4.

View Article: PubMed Central - PubMed

ABSTRACT

Tuberculosis (TB) is the leading cause of morbidity and mortality among all infectious diseases. Failure of Bacillus Calmette Guerin as a vaccine and serious side-effects and toxicity due to long-term TB drug regime are the major hurdles associated with TB control. The problem is further compounded by the emergence of drug-resistance strains of Mycobacterium tuberculosis (Mtb). Consequently, it demands a serious attempt to explore safer and superior treatment approaches. Recently, an improved understanding of host&ndash;pathogen interaction has opened up new avenues for immunotherapy for treating TB. Although, dendritic cells (DCs) show a profound role in generating immunity against Mtb, their immunotherapeutic potential needs to be precisely investigated in controlling TB. Here, we have devised an approach of bolstering DCs efficacy against Mtb by delivering signals through CD40 and TLR-4 molecules. We found that DCs triggered through CD40 and TLR-4 showed increased secretion of IL-12, IL-6, and TNF-&alpha;. It also augmented autophagy. Interestingly, CD40 and TLR-4 stimulation along with the suboptimal dose of anti-TB drugs significantly fortified their efficacy to kill Mtb. Importantly, animals treated with the agonists of CD40 and TLR-4 boosted Th1 and Th17 immunity. Furthermore, it amplified the pool of memory CD4 T cells as well as CD8 T cells. Furthermore, substantial reduction in the bacterial burden in the lungs was observed. Notably, this adjunct therapy employing immunomodulators and chemotherapy can reinvigorate host immunity suppressed due to drugs and Mtb. Moreover, it would strengthen the potency of drugs in curing TB.

No MeSH data available.