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Mycobacterium tuberculosis and Human Immunodeficiency Virus Type 1 Cooperatively Modulate Macrophage Apoptosis via Toll Like Receptor 2 and Calcium Homeostasis.

Mehto S, Antony C, Khan N, Arya R, Selvakumar A, Tiwari BK, Vashishta M, Singh Y, Jameel S, Natarajan K - PLoS ONE (2015)

Bottom Line: Further, molecular sensors of intracellular calcium release aid in antigen mediated inhibition of apoptosis.A cross-regulation between oxidative burst and differential routing of calcium influx governed apoptosis.Interestingly, the HIV-1 Nef supported anti-apoptotic responses in macrophages whereas Vpu had no significant effect.

View Article: PubMed Central - PubMed

Affiliation: Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi 110007, India.

ABSTRACT
The emergence of drug resistant strains of Mycobacterium tuberculosis (M. tuberculosis) together with reports of co-infections with the human immunodeficiency virus (HIV) has renewed interest to better understand the intricate mechanisms prevalent during co-infections. In this study we report a synergistic effect of M. tuberculosis and HIV-1, and their antigens Rv3416 and Nef, respectively, in inhibiting apoptosis of macrophages. This inhibition involves the TLR2 pathway and second messengers that play complementing and contrasting roles in regulating apoptosis. Interestingly, the route of calcium influx into cells differentially regulates apoptosis during antigenic co-stimulation. While calcium released from intracellular stores was anti-apoptotic, calcium influx from the external milieu was pro-apoptotic. Further, molecular sensors of intracellular calcium release aid in antigen mediated inhibition of apoptosis. A cross-regulation between oxidative burst and differential routing of calcium influx governed apoptosis. Interestingly, the HIV-1 Nef supported anti-apoptotic responses in macrophages whereas Vpu had no significant effect. These results point to a synergistic liaison between M. tuberculosis and HIV-1 in regulating macrophage apoptosis.

No MeSH data available.


Related in: MedlinePlus

MyD88, IRAK1 and TRAF6 regulate Rv3416 and Nef mediated inhibition of apoptosis in macrophages.For Panel A, PMA stimulated THP1 cells were transfected with control siRNAs (thin lines) or specific siRNAs to indicated molecules (thick lines) for 36h followed by stimulations with 1 μg/ml Pam3CSK4 (Pam) along with 20 μg/ml Rv3416 and 15 μg/ml Nef for 24h. Cells were stained with Annexin V-APC. Data from one of three independent experiments are shown. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. For Panel B, cytoplasmic extracts from cells cultured as described above were probed for indicated molecules and analyzed by western blots. MOCK represents cells transfected with control siRNAs. Numbers below the blots indicate the relative intensities of the bands. Data from one of three experiments are shown. In Panel A, P<0.04 Control siRNA+Pam+Rv3416+Nef vs siTRAF6+Pam+Rv3416+Nef.
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pone.0131767.g003: MyD88, IRAK1 and TRAF6 regulate Rv3416 and Nef mediated inhibition of apoptosis in macrophages.For Panel A, PMA stimulated THP1 cells were transfected with control siRNAs (thin lines) or specific siRNAs to indicated molecules (thick lines) for 36h followed by stimulations with 1 μg/ml Pam3CSK4 (Pam) along with 20 μg/ml Rv3416 and 15 μg/ml Nef for 24h. Cells were stained with Annexin V-APC. Data from one of three independent experiments are shown. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. For Panel B, cytoplasmic extracts from cells cultured as described above were probed for indicated molecules and analyzed by western blots. MOCK represents cells transfected with control siRNAs. Numbers below the blots indicate the relative intensities of the bands. Data from one of three experiments are shown. In Panel A, P<0.04 Control siRNA+Pam+Rv3416+Nef vs siTRAF6+Pam+Rv3416+Nef.

Mentions: Since HIV-1 Nef is known to recruit downstream molecules of TLR pathways such as TRAF6, TRAF5 and TRAF2 and modulate HIV-1 replication in macrophage [25], therefore, to further confirm the role of TLR2 in mediating macrophage apoptosis, we next investigated the role of different intermediates in the TLR signaling pathway. To that end using specific siRNAs we individually knockdown MyD88, TRAF6 and IRAK1 and monitored apoptosis by Annexin V staining and the expression levels of AIF and Bcl2 as representative pro- and anti-apoptotic molecules, respectively. As shown in (Fig 3A and 3B), Annexin V staining was increased upon knockdown of MyD88 (albeit marginally), IRAK1 or TRAF6. Similarly, co-stimulation with Rv3416 and Nef along with TLR2 stimulation increased the levels of AIF and marginally decreased the levels of Bcl2 following knockdown of IRAK1. These results indicate that the two antigens employ the TLR pathway in regulating macrophage apoptosis during HIV/M. tuberculosis co-infection.


Mycobacterium tuberculosis and Human Immunodeficiency Virus Type 1 Cooperatively Modulate Macrophage Apoptosis via Toll Like Receptor 2 and Calcium Homeostasis.

Mehto S, Antony C, Khan N, Arya R, Selvakumar A, Tiwari BK, Vashishta M, Singh Y, Jameel S, Natarajan K - PLoS ONE (2015)

MyD88, IRAK1 and TRAF6 regulate Rv3416 and Nef mediated inhibition of apoptosis in macrophages.For Panel A, PMA stimulated THP1 cells were transfected with control siRNAs (thin lines) or specific siRNAs to indicated molecules (thick lines) for 36h followed by stimulations with 1 μg/ml Pam3CSK4 (Pam) along with 20 μg/ml Rv3416 and 15 μg/ml Nef for 24h. Cells were stained with Annexin V-APC. Data from one of three independent experiments are shown. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. For Panel B, cytoplasmic extracts from cells cultured as described above were probed for indicated molecules and analyzed by western blots. MOCK represents cells transfected with control siRNAs. Numbers below the blots indicate the relative intensities of the bands. Data from one of three experiments are shown. In Panel A, P<0.04 Control siRNA+Pam+Rv3416+Nef vs siTRAF6+Pam+Rv3416+Nef.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4489497&req=5

pone.0131767.g003: MyD88, IRAK1 and TRAF6 regulate Rv3416 and Nef mediated inhibition of apoptosis in macrophages.For Panel A, PMA stimulated THP1 cells were transfected with control siRNAs (thin lines) or specific siRNAs to indicated molecules (thick lines) for 36h followed by stimulations with 1 μg/ml Pam3CSK4 (Pam) along with 20 μg/ml Rv3416 and 15 μg/ml Nef for 24h. Cells were stained with Annexin V-APC. Data from one of three independent experiments are shown. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. For Panel B, cytoplasmic extracts from cells cultured as described above were probed for indicated molecules and analyzed by western blots. MOCK represents cells transfected with control siRNAs. Numbers below the blots indicate the relative intensities of the bands. Data from one of three experiments are shown. In Panel A, P<0.04 Control siRNA+Pam+Rv3416+Nef vs siTRAF6+Pam+Rv3416+Nef.
Mentions: Since HIV-1 Nef is known to recruit downstream molecules of TLR pathways such as TRAF6, TRAF5 and TRAF2 and modulate HIV-1 replication in macrophage [25], therefore, to further confirm the role of TLR2 in mediating macrophage apoptosis, we next investigated the role of different intermediates in the TLR signaling pathway. To that end using specific siRNAs we individually knockdown MyD88, TRAF6 and IRAK1 and monitored apoptosis by Annexin V staining and the expression levels of AIF and Bcl2 as representative pro- and anti-apoptotic molecules, respectively. As shown in (Fig 3A and 3B), Annexin V staining was increased upon knockdown of MyD88 (albeit marginally), IRAK1 or TRAF6. Similarly, co-stimulation with Rv3416 and Nef along with TLR2 stimulation increased the levels of AIF and marginally decreased the levels of Bcl2 following knockdown of IRAK1. These results indicate that the two antigens employ the TLR pathway in regulating macrophage apoptosis during HIV/M. tuberculosis co-infection.

Bottom Line: Further, molecular sensors of intracellular calcium release aid in antigen mediated inhibition of apoptosis.A cross-regulation between oxidative burst and differential routing of calcium influx governed apoptosis.Interestingly, the HIV-1 Nef supported anti-apoptotic responses in macrophages whereas Vpu had no significant effect.

View Article: PubMed Central - PubMed

Affiliation: Infectious Disease Immunology Lab, Dr. B. R. Ambedkar Centre for Biomedical Research, University of Delhi, Delhi 110007, India.

ABSTRACT
The emergence of drug resistant strains of Mycobacterium tuberculosis (M. tuberculosis) together with reports of co-infections with the human immunodeficiency virus (HIV) has renewed interest to better understand the intricate mechanisms prevalent during co-infections. In this study we report a synergistic effect of M. tuberculosis and HIV-1, and their antigens Rv3416 and Nef, respectively, in inhibiting apoptosis of macrophages. This inhibition involves the TLR2 pathway and second messengers that play complementing and contrasting roles in regulating apoptosis. Interestingly, the route of calcium influx into cells differentially regulates apoptosis during antigenic co-stimulation. While calcium released from intracellular stores was anti-apoptotic, calcium influx from the external milieu was pro-apoptotic. Further, molecular sensors of intracellular calcium release aid in antigen mediated inhibition of apoptosis. A cross-regulation between oxidative burst and differential routing of calcium influx governed apoptosis. Interestingly, the HIV-1 Nef supported anti-apoptotic responses in macrophages whereas Vpu had no significant effect. These results point to a synergistic liaison between M. tuberculosis and HIV-1 in regulating macrophage apoptosis.

No MeSH data available.


Related in: MedlinePlus