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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

Molecular sensors of calcium influx regulate inhibition of apoptosis by Rv3416 and Nef 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. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. Data from one of three independent experiments are shown. For Panel B, PMA stimulated THP1 cells were transfected with siRNAs to indicated molecules for 36h followed by stimulations with 1 μg/ml Pam3CSK4 along with 20 μg/ml Rv3416 or 15 μg/ml Nef or both for 24h. Cytoplasmic extracts 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<0.009 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM1; P<0.02 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM2; P<0.01 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siORAI1.
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pone.0131767.g005: Molecular sensors of calcium influx regulate inhibition of apoptosis by Rv3416 and Nef 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. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. Data from one of three independent experiments are shown. For Panel B, PMA stimulated THP1 cells were transfected with siRNAs to indicated molecules for 36h followed by stimulations with 1 μg/ml Pam3CSK4 along with 20 μg/ml Rv3416 or 15 μg/ml Nef or both for 24h. Cytoplasmic extracts 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<0.009 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM1; P<0.02 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM2; P<0.01 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siORAI1.

Mentions: We further dissected the role of intracellular sensors regulating calcium homeostasis in governing apoptosis by the two antigens. We investigated the roles of STIM1 and STIM2, the molecular sensors that regulate Store Operated Calcium Entry (SOCE) via the Calcium Release Activated Calcium Channel (CRAC) ORAI1. As shown in (Fig 5), knockdown of STIM1, STIM2 or ORAI1, increased apoptosis by increasing Annexin V levels (Fig 5A) and levels of AIF while decreasing the levels of anti-apoptotic molecule Bcl2 (Fig 5B). This indicated that members of the SOCE pathway regulate macrophage apoptosis during M. tuberculosis and HIV co-infection. Further it also complemented the data in (Fig 4), wherein inhibiting calcium from internal stores was pro-apoptotic. This further established a critical role for calcium in regulating macrophage apoptosis during 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)

Molecular sensors of calcium influx regulate inhibition of apoptosis by Rv3416 and Nef 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. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. Data from one of three independent experiments are shown. For Panel B, PMA stimulated THP1 cells were transfected with siRNAs to indicated molecules for 36h followed by stimulations with 1 μg/ml Pam3CSK4 along with 20 μg/ml Rv3416 or 15 μg/ml Nef or both for 24h. Cytoplasmic extracts 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<0.009 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM1; P<0.02 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM2; P<0.01 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siORAI1.
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pone.0131767.g005: Molecular sensors of calcium influx regulate inhibition of apoptosis by Rv3416 and Nef 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. Bar graphs adjacent to histograms in Panel A show relative MFIs of the histograms. Data from one of three independent experiments are shown. For Panel B, PMA stimulated THP1 cells were transfected with siRNAs to indicated molecules for 36h followed by stimulations with 1 μg/ml Pam3CSK4 along with 20 μg/ml Rv3416 or 15 μg/ml Nef or both for 24h. Cytoplasmic extracts 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<0.009 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM1; P<0.02 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siSTIM2; P<0.01 for Pam+Rv3416+Nef vs Pam+Rv3416+Nef+siORAI1.
Mentions: We further dissected the role of intracellular sensors regulating calcium homeostasis in governing apoptosis by the two antigens. We investigated the roles of STIM1 and STIM2, the molecular sensors that regulate Store Operated Calcium Entry (SOCE) via the Calcium Release Activated Calcium Channel (CRAC) ORAI1. As shown in (Fig 5), knockdown of STIM1, STIM2 or ORAI1, increased apoptosis by increasing Annexin V levels (Fig 5A) and levels of AIF while decreasing the levels of anti-apoptotic molecule Bcl2 (Fig 5B). This indicated that members of the SOCE pathway regulate macrophage apoptosis during M. tuberculosis and HIV co-infection. Further it also complemented the data in (Fig 4), wherein inhibiting calcium from internal stores was pro-apoptotic. This further established a critical role for calcium in regulating macrophage apoptosis during 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