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Myeloid Cell Arg1 Inhibits Control of Arthritogenic Alphavirus Infection by Suppressing Antiviral T Cells.

Burrack KS, Tan JJ, McCarthy MK, Her Z, Berger JN, Ng LF, Morrison TE - PLoS Pathog. (2015)

Bottom Line: These mosquito-transmitted viruses cause inflammation and injury in skeletal muscle and joint tissues that results in debilitating pain.Here, we show that Arg1, along with other genes associated with suppressive myeloid cells, is induced in PBMCs isolated from CHIKV-infected patients during the acute phase as well as the chronic phase, and that high Arg1 expression levels were associated with high viral loads and disease severity.Collectively, these data enhance our understanding of the immune response following arthritogenic alphavirus infection and suggest that immunosuppressive myeloid cells may contribute to the duration or severity of these debilitating infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America.

ABSTRACT
Arthritogenic alphaviruses, including Ross River virus (RRV) and chikungunya virus (CHIKV), are responsible for explosive epidemics involving millions of cases. These mosquito-transmitted viruses cause inflammation and injury in skeletal muscle and joint tissues that results in debilitating pain. We previously showed that arginase 1 (Arg1) was highly expressed in myeloid cells in the infected and inflamed musculoskeletal tissues of RRV- and CHIKV-infected mice, and specific deletion of Arg1 from myeloid cells resulted in enhanced viral control. Here, we show that Arg1, along with other genes associated with suppressive myeloid cells, is induced in PBMCs isolated from CHIKV-infected patients during the acute phase as well as the chronic phase, and that high Arg1 expression levels were associated with high viral loads and disease severity. Depletion of both CD4 and CD8 T cells from RRV-infected Arg1-deficient mice restored viral loads to levels detected in T cell-depleted wild-type mice. Moreover, Arg1-expressing myeloid cells inhibited virus-specific T cells in the inflamed and infected musculoskeletal tissues, but not lymphoid tissues, following RRV infection in mice, including suppression of interferon-γ and CD69 expression. Collectively, these data enhance our understanding of the immune response following arthritogenic alphavirus infection and suggest that immunosuppressive myeloid cells may contribute to the duration or severity of these debilitating infections.

No MeSH data available.


Related in: MedlinePlus

Muscle-infiltrating CD4+ and CD8+ T cells isolated from LysMcre;Arg1F/F mice express enhanced IFN-γ transcript.(A) Representative flow plots demonstrating the gating strategy to FACS-sort CD19-CD3+CD4+CD8- and CD19-CD3+CD8+CD4- T cells isolated from quadriceps muscles of RRV-infected WT or LysMcre;Arg1F/F mice at 10 dpi and the post-sort purities. RT-qPCR analysis of (B) IFN-γ, (C) TNF-α, (D) IL-10, and (E) IL-2 expression in FACS-sorted T cells from the spleen of a mock-inoculated mouse (n = 1) or from the quadriceps muscle of RRV-infected WT (n = 3) or LysMcre;Arg1F/F mice (n = 3) at 10 dpi. Data are normalized to 18S rRNA levels and are expressed as the relative expression (n-fold increase) over expression in spleen T cells from a mock-inoculated mouse. Data are represented as the arithmetic mean ± SEM. Data are representative of two independent experiments. P-values determined by two-tailed, unpaired t-tests with or without Welch’s correction. nd, not detected.
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ppat.1005191.g008: Muscle-infiltrating CD4+ and CD8+ T cells isolated from LysMcre;Arg1F/F mice express enhanced IFN-γ transcript.(A) Representative flow plots demonstrating the gating strategy to FACS-sort CD19-CD3+CD4+CD8- and CD19-CD3+CD8+CD4- T cells isolated from quadriceps muscles of RRV-infected WT or LysMcre;Arg1F/F mice at 10 dpi and the post-sort purities. RT-qPCR analysis of (B) IFN-γ, (C) TNF-α, (D) IL-10, and (E) IL-2 expression in FACS-sorted T cells from the spleen of a mock-inoculated mouse (n = 1) or from the quadriceps muscle of RRV-infected WT (n = 3) or LysMcre;Arg1F/F mice (n = 3) at 10 dpi. Data are normalized to 18S rRNA levels and are expressed as the relative expression (n-fold increase) over expression in spleen T cells from a mock-inoculated mouse. Data are represented as the arithmetic mean ± SEM. Data are representative of two independent experiments. P-values determined by two-tailed, unpaired t-tests with or without Welch’s correction. nd, not detected.

Mentions: To further explore the effects of Arg1 on T cell function, we investigated the cytokine expression levels in T cells sorted from muscle tissue of RRV-infected WT and LysMcre;Arg1F/F mice. At 10 dpi, quadriceps muscle tissue was dissected and enzymatically digested, and infiltrating leukocytes were stained for CD3, CD19, CD4, and CD8. CD4+ and CD8+ T cells were FACS-sorted by gating on CD3+CD19- cells and then gating individually on CD4+ T cells and CD8+ T cells (Fig 8A). Gene expression analysis of the sorted T cell subsets was compared to respective T cells sorted from the spleen of a mock-infected mouse. Both CD4+ and CD8+ T cell subsets isolated from LysMcre;Arg1F/F mice expressed increased levels of IFN-γ compared to T cells sorted from WT mice (Fig 8B). T cells sorted from the spleens of RRV-infected WT or LysMcre;Arg1F/F mice showed no difference in IFN-γ expression (S4 Fig). CD4+ T cells sorted from LysMcre;Arg1F/F mice also expressed elevated levels of TNF-α (Fig 8C) and IL-10 (Fig 8D) transcripts. In contrast, CD8+ T cells sorted from WT or LysMcre;Arg1F/F mice expressed similar levels of TNF-α, and IL-10 expression was not detected in this T cell subset. Additionally, IL-2 expression was not detected in either T cell subset (Fig 8E). To further confirm cytokine expression, T cells from RRV-infected WT mice isolated at 10 dpi were restimulated ex vivo with anti-CD3 and anti-CD28 antibodies followed by intracellular cytokine staining. A subset of CD4+ T cells produced both IFN-γ and IL-10, whereas CD8+ T cells produced IFN-γ but very little IL-10 (S5 Fig). These data suggest that Arg1 activity in macrophages inhibits cytokine expression, including IFN-γ, by T cells in musculoskeletal tissues, which may be one mechanism by which Arg1 influences viral loads.


Myeloid Cell Arg1 Inhibits Control of Arthritogenic Alphavirus Infection by Suppressing Antiviral T Cells.

Burrack KS, Tan JJ, McCarthy MK, Her Z, Berger JN, Ng LF, Morrison TE - PLoS Pathog. (2015)

Muscle-infiltrating CD4+ and CD8+ T cells isolated from LysMcre;Arg1F/F mice express enhanced IFN-γ transcript.(A) Representative flow plots demonstrating the gating strategy to FACS-sort CD19-CD3+CD4+CD8- and CD19-CD3+CD8+CD4- T cells isolated from quadriceps muscles of RRV-infected WT or LysMcre;Arg1F/F mice at 10 dpi and the post-sort purities. RT-qPCR analysis of (B) IFN-γ, (C) TNF-α, (D) IL-10, and (E) IL-2 expression in FACS-sorted T cells from the spleen of a mock-inoculated mouse (n = 1) or from the quadriceps muscle of RRV-infected WT (n = 3) or LysMcre;Arg1F/F mice (n = 3) at 10 dpi. Data are normalized to 18S rRNA levels and are expressed as the relative expression (n-fold increase) over expression in spleen T cells from a mock-inoculated mouse. Data are represented as the arithmetic mean ± SEM. Data are representative of two independent experiments. P-values determined by two-tailed, unpaired t-tests with or without Welch’s correction. nd, not detected.
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Related In: Results  -  Collection

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ppat.1005191.g008: Muscle-infiltrating CD4+ and CD8+ T cells isolated from LysMcre;Arg1F/F mice express enhanced IFN-γ transcript.(A) Representative flow plots demonstrating the gating strategy to FACS-sort CD19-CD3+CD4+CD8- and CD19-CD3+CD8+CD4- T cells isolated from quadriceps muscles of RRV-infected WT or LysMcre;Arg1F/F mice at 10 dpi and the post-sort purities. RT-qPCR analysis of (B) IFN-γ, (C) TNF-α, (D) IL-10, and (E) IL-2 expression in FACS-sorted T cells from the spleen of a mock-inoculated mouse (n = 1) or from the quadriceps muscle of RRV-infected WT (n = 3) or LysMcre;Arg1F/F mice (n = 3) at 10 dpi. Data are normalized to 18S rRNA levels and are expressed as the relative expression (n-fold increase) over expression in spleen T cells from a mock-inoculated mouse. Data are represented as the arithmetic mean ± SEM. Data are representative of two independent experiments. P-values determined by two-tailed, unpaired t-tests with or without Welch’s correction. nd, not detected.
Mentions: To further explore the effects of Arg1 on T cell function, we investigated the cytokine expression levels in T cells sorted from muscle tissue of RRV-infected WT and LysMcre;Arg1F/F mice. At 10 dpi, quadriceps muscle tissue was dissected and enzymatically digested, and infiltrating leukocytes were stained for CD3, CD19, CD4, and CD8. CD4+ and CD8+ T cells were FACS-sorted by gating on CD3+CD19- cells and then gating individually on CD4+ T cells and CD8+ T cells (Fig 8A). Gene expression analysis of the sorted T cell subsets was compared to respective T cells sorted from the spleen of a mock-infected mouse. Both CD4+ and CD8+ T cell subsets isolated from LysMcre;Arg1F/F mice expressed increased levels of IFN-γ compared to T cells sorted from WT mice (Fig 8B). T cells sorted from the spleens of RRV-infected WT or LysMcre;Arg1F/F mice showed no difference in IFN-γ expression (S4 Fig). CD4+ T cells sorted from LysMcre;Arg1F/F mice also expressed elevated levels of TNF-α (Fig 8C) and IL-10 (Fig 8D) transcripts. In contrast, CD8+ T cells sorted from WT or LysMcre;Arg1F/F mice expressed similar levels of TNF-α, and IL-10 expression was not detected in this T cell subset. Additionally, IL-2 expression was not detected in either T cell subset (Fig 8E). To further confirm cytokine expression, T cells from RRV-infected WT mice isolated at 10 dpi were restimulated ex vivo with anti-CD3 and anti-CD28 antibodies followed by intracellular cytokine staining. A subset of CD4+ T cells produced both IFN-γ and IL-10, whereas CD8+ T cells produced IFN-γ but very little IL-10 (S5 Fig). These data suggest that Arg1 activity in macrophages inhibits cytokine expression, including IFN-γ, by T cells in musculoskeletal tissues, which may be one mechanism by which Arg1 influences viral loads.

Bottom Line: These mosquito-transmitted viruses cause inflammation and injury in skeletal muscle and joint tissues that results in debilitating pain.Here, we show that Arg1, along with other genes associated with suppressive myeloid cells, is induced in PBMCs isolated from CHIKV-infected patients during the acute phase as well as the chronic phase, and that high Arg1 expression levels were associated with high viral loads and disease severity.Collectively, these data enhance our understanding of the immune response following arthritogenic alphavirus infection and suggest that immunosuppressive myeloid cells may contribute to the duration or severity of these debilitating infections.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America.

ABSTRACT
Arthritogenic alphaviruses, including Ross River virus (RRV) and chikungunya virus (CHIKV), are responsible for explosive epidemics involving millions of cases. These mosquito-transmitted viruses cause inflammation and injury in skeletal muscle and joint tissues that results in debilitating pain. We previously showed that arginase 1 (Arg1) was highly expressed in myeloid cells in the infected and inflamed musculoskeletal tissues of RRV- and CHIKV-infected mice, and specific deletion of Arg1 from myeloid cells resulted in enhanced viral control. Here, we show that Arg1, along with other genes associated with suppressive myeloid cells, is induced in PBMCs isolated from CHIKV-infected patients during the acute phase as well as the chronic phase, and that high Arg1 expression levels were associated with high viral loads and disease severity. Depletion of both CD4 and CD8 T cells from RRV-infected Arg1-deficient mice restored viral loads to levels detected in T cell-depleted wild-type mice. Moreover, Arg1-expressing myeloid cells inhibited virus-specific T cells in the inflamed and infected musculoskeletal tissues, but not lymphoid tissues, following RRV infection in mice, including suppression of interferon-γ and CD69 expression. Collectively, these data enhance our understanding of the immune response following arthritogenic alphavirus infection and suggest that immunosuppressive myeloid cells may contribute to the duration or severity of these debilitating infections.

No MeSH data available.


Related in: MedlinePlus