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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 through C40.T4 enhanced the production of cytokines and expression of CD80, CD86, and MHCII on Mtb-infected DCs. Mtb-infected DCs were stimulated through C40.T4 for 24 h. Control cultures were also set using CD40A, TLR4L, isotype-matched controls, and medium alone. Later, SNs were harvested for the detection of (A) IL-6; (B) IL-12; (C) TNF-α; (D) IL-10 by ELISA and expressed as pg/ml. Data shown as mean ± SD are normalized with their respective isotype-matched controls. CD11c+ DCs were phenotyped by flowcytometry for the expression of (E) CD80 (p < 0.001); (F) CD86 (p < 0.01); (G) MHCII. Data expressed as mean ± SD of percent positive cells are representative of three independent experiments. “*,” “**,” and “***” indicate p < 0.05, p < 0.01, and p < 0.001, respectively.
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Figure 1: Signaling through C40.T4 enhanced the production of cytokines and expression of CD80, CD86, and MHCII on Mtb-infected DCs. Mtb-infected DCs were stimulated through C40.T4 for 24 h. Control cultures were also set using CD40A, TLR4L, isotype-matched controls, and medium alone. Later, SNs were harvested for the detection of (A) IL-6; (B) IL-12; (C) TNF-α; (D) IL-10 by ELISA and expressed as pg/ml. Data shown as mean ± SD are normalized with their respective isotype-matched controls. CD11c+ DCs were phenotyped by flowcytometry for the expression of (E) CD80 (p < 0.001); (F) CD86 (p < 0.01); (G) MHCII. Data expressed as mean ± SD of percent positive cells are representative of three independent experiments. “*,” “**,” and “***” indicate p < 0.05, p < 0.01, and p < 0.001, respectively.

Mentions: The aim of the current study was to activate Mtb-infected DCs through C40.T4 and, consequently, to control the growth of the pathogen. We observed that C40.T4 stimulation improved the potency of infected DCs to produce cytokines, such as IL-6 (p < 0.001), IL-12 (p < 0.0001), and TNF-α (p < 0.001) (Figures 1A–C). No change was noted in IL-10 (Figure 1D). Similarly, infected macrophages stimulated with C40.T4 augmented the secretion of IL-6 (p < 0.05) (Figure S2B in Supplementary Material). Furthermore, Mtb-infected DCs stimulated through C40.T4 expressed considerably higher levels of costimulatory molecules CD80 (p < 0.01) and CD86 (p < 0.01), as compared to control (Figures 1E–G). However, not much change was observed in the expression of MHCII. It may be due to saturation in the expression of MHCII on DCs upon infection with Mtb.


Stimulation through CD40 and TLR-4 Is an Effective Host Directed Therapy against Mycobacterium tuberculosis
Signaling through C40.T4 enhanced the production of cytokines and expression of CD80, CD86, and MHCII on Mtb-infected DCs. Mtb-infected DCs were stimulated through C40.T4 for 24 h. Control cultures were also set using CD40A, TLR4L, isotype-matched controls, and medium alone. Later, SNs were harvested for the detection of (A) IL-6; (B) IL-12; (C) TNF-α; (D) IL-10 by ELISA and expressed as pg/ml. Data shown as mean ± SD are normalized with their respective isotype-matched controls. CD11c+ DCs were phenotyped by flowcytometry for the expression of (E) CD80 (p < 0.001); (F) CD86 (p < 0.01); (G) MHCII. Data expressed as mean ± SD of percent positive cells are representative of three independent experiments. “*,” “**,” and “***” indicate p < 0.05, p < 0.01, and p < 0.001, respectively.
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Figure 1: Signaling through C40.T4 enhanced the production of cytokines and expression of CD80, CD86, and MHCII on Mtb-infected DCs. Mtb-infected DCs were stimulated through C40.T4 for 24 h. Control cultures were also set using CD40A, TLR4L, isotype-matched controls, and medium alone. Later, SNs were harvested for the detection of (A) IL-6; (B) IL-12; (C) TNF-α; (D) IL-10 by ELISA and expressed as pg/ml. Data shown as mean ± SD are normalized with their respective isotype-matched controls. CD11c+ DCs were phenotyped by flowcytometry for the expression of (E) CD80 (p < 0.001); (F) CD86 (p < 0.01); (G) MHCII. Data expressed as mean ± SD of percent positive cells are representative of three independent experiments. “*,” “**,” and “***” indicate p < 0.05, p < 0.01, and p < 0.001, respectively.
Mentions: The aim of the current study was to activate Mtb-infected DCs through C40.T4 and, consequently, to control the growth of the pathogen. We observed that C40.T4 stimulation improved the potency of infected DCs to produce cytokines, such as IL-6 (p < 0.001), IL-12 (p < 0.0001), and TNF-α (p < 0.001) (Figures 1A–C). No change was noted in IL-10 (Figure 1D). Similarly, infected macrophages stimulated with C40.T4 augmented the secretion of IL-6 (p < 0.05) (Figure S2B in Supplementary Material). Furthermore, Mtb-infected DCs stimulated through C40.T4 expressed considerably higher levels of costimulatory molecules CD80 (p < 0.01) and CD86 (p < 0.01), as compared to control (Figures 1E–G). However, not much change was observed in the expression of MHCII. It may be due to saturation in the expression of MHCII on DCs upon infection with Mtb.

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.