Limits...
Maladjusted host immune responses induce experimental cerebral malaria-like pathology in a murine Borrelia and Plasmodium co-infection model.

Normark J, Nelson M, Engström P, Andersson M, Björk R, Moritz T, Fahlgren A, Bergström S - PLoS ONE (2014)

Bottom Line: It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium.Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells.In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden; Umeå Center for Microbial Research, Umeå University, Umeå, Sweden; Division of Infectious diseases, Department of Clinical Microbiology, Umeå University, Umeå, Sweden.

ABSTRACT
In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1β and TNF-α, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells.

Show MeSH

Related in: MedlinePlus

Dynamic MHCII presentation and delayed activation of MΦs during co-infection.Spleen mononuclear cells were extracted on consecutive days from single and co-infected mice. They were stained and counted in a LCRII flow cytometer (N = 6 per group) experiment performed in duplicate. (A) The percentage fraction of MHCII expressing cells in the F4/80+ population of SMCs. (B) The proportion of F4/80+MHCII+ MΦs expressing MHCII to a high extent (MHCII+high). (C) The fraction of CD11c+ DCs expressing the activation marker CD86. (D) The fraction of F4/80+MHCII+low cells expressing CD86. (E) The fraction of F4/80+MHCII+high cells expressing CD86, (▪) indicates mice infected with both P. berghei and B. duttonii, (○) B. duttonii infected animals, and (Δ) mice infected with P. berghei.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4116174&req=5

pone-0103295-g005: Dynamic MHCII presentation and delayed activation of MΦs during co-infection.Spleen mononuclear cells were extracted on consecutive days from single and co-infected mice. They were stained and counted in a LCRII flow cytometer (N = 6 per group) experiment performed in duplicate. (A) The percentage fraction of MHCII expressing cells in the F4/80+ population of SMCs. (B) The proportion of F4/80+MHCII+ MΦs expressing MHCII to a high extent (MHCII+high). (C) The fraction of CD11c+ DCs expressing the activation marker CD86. (D) The fraction of F4/80+MHCII+low cells expressing CD86. (E) The fraction of F4/80+MHCII+high cells expressing CD86, (▪) indicates mice infected with both P. berghei and B. duttonii, (○) B. duttonii infected animals, and (Δ) mice infected with P. berghei.

Mentions: In order to unravel the origin of the affected peripheral cytokine levels during co-infection, the antigen presentation potential and activation of immune regulating cells in the spleen were evaluated and quantified. Total spleen cells from single P. berghei, single B. duttonii and co-infected mice (N = 6 from each infection type and time point) were isolated at day 0–5 p.i. Dendritic cells (DCs) and macrophages (MΦ) were analyzed for expression of the cells surface markers MHCI and MHCII, and the co-stimulatory molecules CD83 and CD86 (Figures 4 and 5). We found that the different modes and duration of infection greatly influenced the mean fluorescence intensity (MFI) of MHCII+ on both DCs and MΦs (the amount of MHCII molecules present on the cell surface is directly proportional to the MFI). In both single- and co-infected tissues, we detected and gated two distinct populations with high (MHCII+high) and low (MHCII+low) expression of MHCII (Figures S2 and S3) reflecting the state of maturity of the DCs since mature DCs present more MHCII molecules on the surface than their immature counterparts [43], [44]. MHCII+high expressing DCs presumably efficiently propagate signal to recipient T-cell effectors. Consistent with data from other groups [13][12] we observed that single P. berghei infection showed reduced MHCII expression by DCs (MHCII in total, Figure 4A, day 5 p.i. and MHCII+highFigure 4B, all time points p.i. significantly lower compared to uninfected control, Table S2), while DCs from B. duttonii infected mice displayed an oscillating MHCII+high expression curve (Figure 4B), from high (day 1 and 2 p.i.) to low (day 3 p.i.). Dendritic cells from the co-infected animals showed a general increase in MHCII expression on the surface day 2 p.i. (Wilcoxon rank sum test, P = 0.004) and otherwise no MHCII reduction (Figure 4A). The fraction of CD11c+ MHCII+high cells (DCs) remained on the same level as DCs from the uninfected animals day 1–2 p.i., after which the levels dropped to levels observed in B. duttonii infected animals (Figure 4B). In the case of MHCI expression it was present at high levels in 98±0.5% of all CD11c+ cells by (N = 6 animals in each group) and no relative reduction of MHCI expression was seen in any of the infection modalities (data not shown).


Maladjusted host immune responses induce experimental cerebral malaria-like pathology in a murine Borrelia and Plasmodium co-infection model.

Normark J, Nelson M, Engström P, Andersson M, Björk R, Moritz T, Fahlgren A, Bergström S - PLoS ONE (2014)

Dynamic MHCII presentation and delayed activation of MΦs during co-infection.Spleen mononuclear cells were extracted on consecutive days from single and co-infected mice. They were stained and counted in a LCRII flow cytometer (N = 6 per group) experiment performed in duplicate. (A) The percentage fraction of MHCII expressing cells in the F4/80+ population of SMCs. (B) The proportion of F4/80+MHCII+ MΦs expressing MHCII to a high extent (MHCII+high). (C) The fraction of CD11c+ DCs expressing the activation marker CD86. (D) The fraction of F4/80+MHCII+low cells expressing CD86. (E) The fraction of F4/80+MHCII+high cells expressing CD86, (▪) indicates mice infected with both P. berghei and B. duttonii, (○) B. duttonii infected animals, and (Δ) mice infected with P. berghei.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4116174&req=5

pone-0103295-g005: Dynamic MHCII presentation and delayed activation of MΦs during co-infection.Spleen mononuclear cells were extracted on consecutive days from single and co-infected mice. They were stained and counted in a LCRII flow cytometer (N = 6 per group) experiment performed in duplicate. (A) The percentage fraction of MHCII expressing cells in the F4/80+ population of SMCs. (B) The proportion of F4/80+MHCII+ MΦs expressing MHCII to a high extent (MHCII+high). (C) The fraction of CD11c+ DCs expressing the activation marker CD86. (D) The fraction of F4/80+MHCII+low cells expressing CD86. (E) The fraction of F4/80+MHCII+high cells expressing CD86, (▪) indicates mice infected with both P. berghei and B. duttonii, (○) B. duttonii infected animals, and (Δ) mice infected with P. berghei.
Mentions: In order to unravel the origin of the affected peripheral cytokine levels during co-infection, the antigen presentation potential and activation of immune regulating cells in the spleen were evaluated and quantified. Total spleen cells from single P. berghei, single B. duttonii and co-infected mice (N = 6 from each infection type and time point) were isolated at day 0–5 p.i. Dendritic cells (DCs) and macrophages (MΦ) were analyzed for expression of the cells surface markers MHCI and MHCII, and the co-stimulatory molecules CD83 and CD86 (Figures 4 and 5). We found that the different modes and duration of infection greatly influenced the mean fluorescence intensity (MFI) of MHCII+ on both DCs and MΦs (the amount of MHCII molecules present on the cell surface is directly proportional to the MFI). In both single- and co-infected tissues, we detected and gated two distinct populations with high (MHCII+high) and low (MHCII+low) expression of MHCII (Figures S2 and S3) reflecting the state of maturity of the DCs since mature DCs present more MHCII molecules on the surface than their immature counterparts [43], [44]. MHCII+high expressing DCs presumably efficiently propagate signal to recipient T-cell effectors. Consistent with data from other groups [13][12] we observed that single P. berghei infection showed reduced MHCII expression by DCs (MHCII in total, Figure 4A, day 5 p.i. and MHCII+highFigure 4B, all time points p.i. significantly lower compared to uninfected control, Table S2), while DCs from B. duttonii infected mice displayed an oscillating MHCII+high expression curve (Figure 4B), from high (day 1 and 2 p.i.) to low (day 3 p.i.). Dendritic cells from the co-infected animals showed a general increase in MHCII expression on the surface day 2 p.i. (Wilcoxon rank sum test, P = 0.004) and otherwise no MHCII reduction (Figure 4A). The fraction of CD11c+ MHCII+high cells (DCs) remained on the same level as DCs from the uninfected animals day 1–2 p.i., after which the levels dropped to levels observed in B. duttonii infected animals (Figure 4B). In the case of MHCI expression it was present at high levels in 98±0.5% of all CD11c+ cells by (N = 6 animals in each group) and no relative reduction of MHCI expression was seen in any of the infection modalities (data not shown).

Bottom Line: It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium.Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells.In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden; Umeå Center for Microbial Research, Umeå University, Umeå, Sweden; Division of Infectious diseases, Department of Clinical Microbiology, Umeå University, Umeå, Sweden.

ABSTRACT
In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1β and TNF-α, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells.

Show MeSH
Related in: MedlinePlus