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A systems immunology approach to plasmacytoid dendritic cell function in cytopathic virus infections.

Bocharov G, Züst R, Cervantes-Barragan L, Luzyanina T, Chiglintsev E, Chereshnev VA, Thiel V, Ludewig B - PLoS Pathog. (2010)

Bottom Line: In order to better understand such multiscale interactions, we have implemented a systems immunology approach focusing on the analysis of the structure, dynamics and operating principles of virus-host interactions which constrain the initial spread of the pathogen.Parameter estimation for the system indicated that on a per capita basis, one infected pDC secretes sufficient type I IFN to protect 10(3) to 10(4) Mphis from cytopathic viral infection.However, the ability of pDCs to protect against severe disease caused by virus variants exhibiting an enhanced liver tropism and higher replication rates appears to be rather limited.

View Article: PubMed Central - PubMed

Affiliation: Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russia.

ABSTRACT
Plasmacytoid dendritic cell (pDC)-mediated protection against cytopathic virus infection involves various molecular, cellular, tissue-scale, and organism-scale events. In order to better understand such multiscale interactions, we have implemented a systems immunology approach focusing on the analysis of the structure, dynamics and operating principles of virus-host interactions which constrain the initial spread of the pathogen. Using high-resolution experimental data sets coming from the well-described mouse hepatitis virus (MHV) model, we first calibrated basic modules including MHV infection of its primary target cells, i.e. pDCs and macrophages (Mphis). These basic building blocks were used to generate and validate an integrative mathematical model for in vivo infection dynamics. Parameter estimation for the system indicated that on a per capita basis, one infected pDC secretes sufficient type I IFN to protect 10(3) to 10(4) Mphis from cytopathic viral infection. This extremely high protective capacity of pDCs secures the spleen's capability to function as a 'sink' for the virus produced in peripheral organs such as the liver. Furthermore, our results suggest that the pDC population in spleen ensures a robust protection against virus variants which substantially down-modulate IFN secretion. However, the ability of pDCs to protect against severe disease caused by virus variants exhibiting an enhanced liver tropism and higher replication rates appears to be rather limited. Taken together, this systems immunology analysis suggests that antiviral therapy against cytopathic viruses should primarily limit viral replication within peripheral target organs.

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MHV infection and IFN response kinetics in vitro.Experimental data (open symbols) represent the geometric mean ±SEM. Virus titers (red), IFN-α concentration (green) and the fraction of live cells out of the total initial target cell number (black) were used to calibrate the model. (A) In vitro MHV infection of pDCs (MOI = 1). Fraction of infected cells in the population of live cells is shown in blue. (B) MHV infection in pDCs derived from ifnar−/− mice. Fraction of infected cells in the population of live cells is shown in blue. Experimental validation had been performed using infection of pDCs with EGFP-recombinant MHV (blue circles). (C) MHV replication in wild-type Mφs. The data on the amount of secreted IFN-α were used to validate the calibrated model (green circles). (D) Effect of IFN pre-treatment (500 IU of IFN-α, green line) on MHV replication in wt Mφs.
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ppat-1001017-g002: MHV infection and IFN response kinetics in vitro.Experimental data (open symbols) represent the geometric mean ±SEM. Virus titers (red), IFN-α concentration (green) and the fraction of live cells out of the total initial target cell number (black) were used to calibrate the model. (A) In vitro MHV infection of pDCs (MOI = 1). Fraction of infected cells in the population of live cells is shown in blue. (B) MHV infection in pDCs derived from ifnar−/− mice. Fraction of infected cells in the population of live cells is shown in blue. Experimental validation had been performed using infection of pDCs with EGFP-recombinant MHV (blue circles). (C) MHV replication in wild-type Mφs. The data on the amount of secreted IFN-α were used to validate the calibrated model (green circles). (D) Effect of IFN pre-treatment (500 IU of IFN-α, green line) on MHV replication in wt Mφs.

Mentions: To estimate the kinetic parameters of MHV-pDC interaction, we used in vitro data on MHV infection of bone marrow-derived pDCs as described previously [8]. The data set characterizes the response of pDCs infection with MHV at a multiplicity of infection (MOI) of 1 (Figure 2A). To delineate a quantitative effect of IFN-α on virus production, additional data from similar experiments conducted with pDCs from mice deficient for the type I IFN receptor (ifnar−/−) were used (Figure 2B). In addition to the MHV/IFN-α data, we considered data on survival kinetics of MHV-infected pDCs from wt and ifnar−/− mice generated independently in a separate series of experiments. The MHV-pDC interaction parameters appearing in the basic model of the type I IFN response (described in Materials and Methods) were estimated by fitting simultaneously the data sets on wt and ifnar−/− cells. The maximum likelihood approach for the log-transformed data was used to quantify the model parameters with the resulting best-fit description of the data by the model shown in Figure 2A and 2B. The resulting calibrated model for the in vitro pDC response to MHV was further validated by comparing its predictions with in vitro infection at an MOI of 0.1 and 0.01 (Figure S1) and also, by determining the fraction of infected cells deduced from experimental data sets using an enhanced green fluorescence protein (EGFP) expressing recombinant MHV [10] (Figure 2A and B). The parameter values summarized in Table 1 provide additional insight into the ‘numbers game’ between the virus and pDCs: (i) the average MHV secretion rate of infected pDCs is rather low with ∼1.7 pfu cell−1 h−1, (ii) the IFN-α level required for 2-fold inhibition of MHV production is about 46 pg/ml, (iii) the average secretion rate of IFN-α per infected pDC is ∼4.4*10−4 pg h−1 or, equivalently, ∼15586 molecules h−1. The latter estimate takes into account that the molecular weight of IFN-α is about 17000 atomic mass units (a.u.) and 1 a.u. = 1.67×10−24 g.


A systems immunology approach to plasmacytoid dendritic cell function in cytopathic virus infections.

Bocharov G, Züst R, Cervantes-Barragan L, Luzyanina T, Chiglintsev E, Chereshnev VA, Thiel V, Ludewig B - PLoS Pathog. (2010)

MHV infection and IFN response kinetics in vitro.Experimental data (open symbols) represent the geometric mean ±SEM. Virus titers (red), IFN-α concentration (green) and the fraction of live cells out of the total initial target cell number (black) were used to calibrate the model. (A) In vitro MHV infection of pDCs (MOI = 1). Fraction of infected cells in the population of live cells is shown in blue. (B) MHV infection in pDCs derived from ifnar−/− mice. Fraction of infected cells in the population of live cells is shown in blue. Experimental validation had been performed using infection of pDCs with EGFP-recombinant MHV (blue circles). (C) MHV replication in wild-type Mφs. The data on the amount of secreted IFN-α were used to validate the calibrated model (green circles). (D) Effect of IFN pre-treatment (500 IU of IFN-α, green line) on MHV replication in wt Mφs.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2908624&req=5

ppat-1001017-g002: MHV infection and IFN response kinetics in vitro.Experimental data (open symbols) represent the geometric mean ±SEM. Virus titers (red), IFN-α concentration (green) and the fraction of live cells out of the total initial target cell number (black) were used to calibrate the model. (A) In vitro MHV infection of pDCs (MOI = 1). Fraction of infected cells in the population of live cells is shown in blue. (B) MHV infection in pDCs derived from ifnar−/− mice. Fraction of infected cells in the population of live cells is shown in blue. Experimental validation had been performed using infection of pDCs with EGFP-recombinant MHV (blue circles). (C) MHV replication in wild-type Mφs. The data on the amount of secreted IFN-α were used to validate the calibrated model (green circles). (D) Effect of IFN pre-treatment (500 IU of IFN-α, green line) on MHV replication in wt Mφs.
Mentions: To estimate the kinetic parameters of MHV-pDC interaction, we used in vitro data on MHV infection of bone marrow-derived pDCs as described previously [8]. The data set characterizes the response of pDCs infection with MHV at a multiplicity of infection (MOI) of 1 (Figure 2A). To delineate a quantitative effect of IFN-α on virus production, additional data from similar experiments conducted with pDCs from mice deficient for the type I IFN receptor (ifnar−/−) were used (Figure 2B). In addition to the MHV/IFN-α data, we considered data on survival kinetics of MHV-infected pDCs from wt and ifnar−/− mice generated independently in a separate series of experiments. The MHV-pDC interaction parameters appearing in the basic model of the type I IFN response (described in Materials and Methods) were estimated by fitting simultaneously the data sets on wt and ifnar−/− cells. The maximum likelihood approach for the log-transformed data was used to quantify the model parameters with the resulting best-fit description of the data by the model shown in Figure 2A and 2B. The resulting calibrated model for the in vitro pDC response to MHV was further validated by comparing its predictions with in vitro infection at an MOI of 0.1 and 0.01 (Figure S1) and also, by determining the fraction of infected cells deduced from experimental data sets using an enhanced green fluorescence protein (EGFP) expressing recombinant MHV [10] (Figure 2A and B). The parameter values summarized in Table 1 provide additional insight into the ‘numbers game’ between the virus and pDCs: (i) the average MHV secretion rate of infected pDCs is rather low with ∼1.7 pfu cell−1 h−1, (ii) the IFN-α level required for 2-fold inhibition of MHV production is about 46 pg/ml, (iii) the average secretion rate of IFN-α per infected pDC is ∼4.4*10−4 pg h−1 or, equivalently, ∼15586 molecules h−1. The latter estimate takes into account that the molecular weight of IFN-α is about 17000 atomic mass units (a.u.) and 1 a.u. = 1.67×10−24 g.

Bottom Line: In order to better understand such multiscale interactions, we have implemented a systems immunology approach focusing on the analysis of the structure, dynamics and operating principles of virus-host interactions which constrain the initial spread of the pathogen.Parameter estimation for the system indicated that on a per capita basis, one infected pDC secretes sufficient type I IFN to protect 10(3) to 10(4) Mphis from cytopathic viral infection.However, the ability of pDCs to protect against severe disease caused by virus variants exhibiting an enhanced liver tropism and higher replication rates appears to be rather limited.

View Article: PubMed Central - PubMed

Affiliation: Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russia.

ABSTRACT
Plasmacytoid dendritic cell (pDC)-mediated protection against cytopathic virus infection involves various molecular, cellular, tissue-scale, and organism-scale events. In order to better understand such multiscale interactions, we have implemented a systems immunology approach focusing on the analysis of the structure, dynamics and operating principles of virus-host interactions which constrain the initial spread of the pathogen. Using high-resolution experimental data sets coming from the well-described mouse hepatitis virus (MHV) model, we first calibrated basic modules including MHV infection of its primary target cells, i.e. pDCs and macrophages (Mphis). These basic building blocks were used to generate and validate an integrative mathematical model for in vivo infection dynamics. Parameter estimation for the system indicated that on a per capita basis, one infected pDC secretes sufficient type I IFN to protect 10(3) to 10(4) Mphis from cytopathic viral infection. This extremely high protective capacity of pDCs secures the spleen's capability to function as a 'sink' for the virus produced in peripheral organs such as the liver. Furthermore, our results suggest that the pDC population in spleen ensures a robust protection against virus variants which substantially down-modulate IFN secretion. However, the ability of pDCs to protect against severe disease caused by virus variants exhibiting an enhanced liver tropism and higher replication rates appears to be rather limited. Taken together, this systems immunology analysis suggests that antiviral therapy against cytopathic viruses should primarily limit viral replication within peripheral target organs.

Show MeSH
Related in: MedlinePlus