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MicroRNA-155 enhances T cell trafficking and antiviral effector function in a model of coronavirus-induced neurologic disease

View Article: PubMed Central - PubMed

ABSTRACT

Background: MicroRNAs (miRNAs) are noncoding RNAs that modulate cellular gene expression, primarily at the post-transcriptional level. We sought to examine the functional role of miR-155 in a model of viral-induced neuroinflammation.

Methods: Acute encephalomyelitis and immune-mediated demyelination were induced by intracranial injection with the neurotropic JHM strain of mouse hepatitis virus (JHMV) into C57BL/6 miR-155+/+ wildtype (WT) mice or miR-155−/− mice. Morbidity and mortality, viral load and immune cell accumulation in the CNS, and spinal cord demyelination were assessed at defined points post-infection. T cells harvested from infected mice were used to examine cytolytic activity, cytokine activity, and expression of certain chemokine receptors. To determine the impact of miR-155 on trafficking, T cells from infected WT or miR-155−/− mice were adoptively transferred into RAG1−/− mice, and T cell accumulation into the CNS was assessed using flow cytometry. Statistical significance was determined using the Mantel-Cox log-rank test or Student’s T tests.

Results: Compared to WT mice, JHMV-infected miR-155−/− mice developed exacerbated disease concomitant with increased morbidity/mortality and an inability to control viral replication within the CNS. In corroboration with increased susceptibility to disease, miR-155−/− mice had diminished CD8+ T cell responses in terms of numbers, cytolytic activity, IFN-γ secretion, and homing to the CNS that corresponded with reduced expression of the chemokine receptor CXCR3. Both IFN-γ secretion and trafficking were impaired in miR-155−/−, virus-specific CD4+ T cells; however, expression of the chemokine homing receptors analyzed on CD4+ cells was not affected. Except for very early during infection, there were not significant differences in macrophage infiltration into the CNS between WT and miR-155−/− JHMV-infected mice, and the severity of demyelination was similar at 14 days p.i. between WT and miR-155−/− JHMV-infected mice.

Conclusions: These findings support a novel role for miR-155 in host defense in a model of viral-induced encephalomyelitis. Specifically, miR-155 enhances antiviral T cell responses including cytokine secretion, cytolytic activity, and homing to the CNS in response to viral infection. Further, miR-155 can play either a host-protective or host-damaging role during neuroinflammation depending on the disease trigger.

No MeSH data available.


Related in: MedlinePlus

T cells from miR-155−/− mice exhibited impaired antiviral effector function. WT and miR-155−/− mice were immunized with DM-MHV via i.p. injection. a Animals were sacrificed 8 days p.i., and CD4+ and CD8+ T cells were isolated and pooled. The frequencies of total and virus-specific CD8+ T cells were determined by tetramer staining [96]. Equivalent numbers of virus-specific CTLs were added to target cells pulsed with either the immunodominant CD8+ T cell epitope within the spike (S) glycoprotein spanning residues 510-518 (S510-518, 50 μM) or control ovalbumin peptide (50 μM) at the indicated ratios, and lytic activity was determined as previously described [31, 96]. In addition, antigen recall responses to the immunodominant CD4 T cell epitope (M133-147) (b) or CD8 T cell epitope S510-518 (c) was performed, and IFN-γ levels were determined by ELISA as previously described [96]. Data are representative of at least two independent experiments, with at least five mice from each group. *p < 0.05; ***p < 0.001
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Fig4: T cells from miR-155−/− mice exhibited impaired antiviral effector function. WT and miR-155−/− mice were immunized with DM-MHV via i.p. injection. a Animals were sacrificed 8 days p.i., and CD4+ and CD8+ T cells were isolated and pooled. The frequencies of total and virus-specific CD8+ T cells were determined by tetramer staining [96]. Equivalent numbers of virus-specific CTLs were added to target cells pulsed with either the immunodominant CD8+ T cell epitope within the spike (S) glycoprotein spanning residues 510-518 (S510-518, 50 μM) or control ovalbumin peptide (50 μM) at the indicated ratios, and lytic activity was determined as previously described [31, 96]. In addition, antigen recall responses to the immunodominant CD4 T cell epitope (M133-147) (b) or CD8 T cell epitope S510-518 (c) was performed, and IFN-γ levels were determined by ELISA as previously described [96]. Data are representative of at least two independent experiments, with at least five mice from each group. *p < 0.05; ***p < 0.001

Mentions: We next examined whether T cell antiviral effector responses were altered in the absence of miR-155 expression. Both cytolytic activity by CD8+ T cells [27, 50, 57, 60], as well as secretion of IFN-γ by virus-specific CD4+ and CD8+ T cells are important for controlling JHMV replication within the CNS [31, 53, 54, 61, 62]. WT and miR-155−/− mice were infected i.p. with DM-JHMV. Splenocytes were removed 8 days p.i., and the antiviral activity of virus-specific T cells was determined. As shown in Fig. 4a, virus-specific, miR-155−/− CD8+ T cells showed reduced (p < 0.05) cytolytic activity compared to WT CD8+ T cells. In addition, secretion of IFN-γ by CD4+ and CD8+ T cells from immunized miR-155−/− mice was reduced (p < 0.001) compared to WT mice (Fig. 4b, c). These findings argue that in the absence of miR-155, virus-specific T cell functions are blunted, consistent with previous reports [21, 22, 24, 25].Fig. 4


MicroRNA-155 enhances T cell trafficking and antiviral effector function in a model of coronavirus-induced neurologic disease
T cells from miR-155−/− mice exhibited impaired antiviral effector function. WT and miR-155−/− mice were immunized with DM-MHV via i.p. injection. a Animals were sacrificed 8 days p.i., and CD4+ and CD8+ T cells were isolated and pooled. The frequencies of total and virus-specific CD8+ T cells were determined by tetramer staining [96]. Equivalent numbers of virus-specific CTLs were added to target cells pulsed with either the immunodominant CD8+ T cell epitope within the spike (S) glycoprotein spanning residues 510-518 (S510-518, 50 μM) or control ovalbumin peptide (50 μM) at the indicated ratios, and lytic activity was determined as previously described [31, 96]. In addition, antigen recall responses to the immunodominant CD4 T cell epitope (M133-147) (b) or CD8 T cell epitope S510-518 (c) was performed, and IFN-γ levels were determined by ELISA as previously described [96]. Data are representative of at least two independent experiments, with at least five mice from each group. *p < 0.05; ***p < 0.001
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Fig4: T cells from miR-155−/− mice exhibited impaired antiviral effector function. WT and miR-155−/− mice were immunized with DM-MHV via i.p. injection. a Animals were sacrificed 8 days p.i., and CD4+ and CD8+ T cells were isolated and pooled. The frequencies of total and virus-specific CD8+ T cells were determined by tetramer staining [96]. Equivalent numbers of virus-specific CTLs were added to target cells pulsed with either the immunodominant CD8+ T cell epitope within the spike (S) glycoprotein spanning residues 510-518 (S510-518, 50 μM) or control ovalbumin peptide (50 μM) at the indicated ratios, and lytic activity was determined as previously described [31, 96]. In addition, antigen recall responses to the immunodominant CD4 T cell epitope (M133-147) (b) or CD8 T cell epitope S510-518 (c) was performed, and IFN-γ levels were determined by ELISA as previously described [96]. Data are representative of at least two independent experiments, with at least five mice from each group. *p < 0.05; ***p < 0.001
Mentions: We next examined whether T cell antiviral effector responses were altered in the absence of miR-155 expression. Both cytolytic activity by CD8+ T cells [27, 50, 57, 60], as well as secretion of IFN-γ by virus-specific CD4+ and CD8+ T cells are important for controlling JHMV replication within the CNS [31, 53, 54, 61, 62]. WT and miR-155−/− mice were infected i.p. with DM-JHMV. Splenocytes were removed 8 days p.i., and the antiviral activity of virus-specific T cells was determined. As shown in Fig. 4a, virus-specific, miR-155−/− CD8+ T cells showed reduced (p < 0.05) cytolytic activity compared to WT CD8+ T cells. In addition, secretion of IFN-γ by CD4+ and CD8+ T cells from immunized miR-155−/− mice was reduced (p < 0.001) compared to WT mice (Fig. 4b, c). These findings argue that in the absence of miR-155, virus-specific T cell functions are blunted, consistent with previous reports [21, 22, 24, 25].Fig. 4

View Article: PubMed Central - PubMed

ABSTRACT

Background: MicroRNAs (miRNAs) are noncoding RNAs that modulate cellular gene expression, primarily at the post-transcriptional level. We sought to examine the functional role of miR-155 in a model of viral-induced neuroinflammation.

Methods: Acute encephalomyelitis and immune-mediated demyelination were induced by intracranial injection with the neurotropic JHM strain of mouse hepatitis virus (JHMV) into C57BL/6 miR-155+/+ wildtype (WT) mice or miR-155&minus;/&minus; mice. Morbidity and mortality, viral load and immune cell accumulation in the CNS, and spinal cord demyelination were assessed at defined points post-infection. T cells harvested from infected mice were used to examine cytolytic activity, cytokine activity, and expression of certain chemokine receptors. To determine the impact of miR-155 on trafficking, T cells from infected WT or miR-155&minus;/&minus; mice were adoptively transferred into RAG1&minus;/&minus; mice, and T cell accumulation into the CNS was assessed using flow cytometry. Statistical significance was determined using the Mantel-Cox log-rank test or Student&rsquo;s T tests.

Results: Compared to WT mice, JHMV-infected miR-155&minus;/&minus; mice developed exacerbated disease concomitant with increased morbidity/mortality and an inability to control viral replication within the CNS. In corroboration with increased susceptibility to disease, miR-155&minus;/&minus; mice had diminished CD8+ T cell responses in terms of numbers, cytolytic activity, IFN-&gamma; secretion, and homing to the CNS that corresponded with reduced expression of the chemokine receptor CXCR3. Both IFN-&gamma; secretion and trafficking were impaired in miR-155&minus;/&minus;, virus-specific CD4+ T cells; however, expression of the chemokine homing receptors analyzed on CD4+ cells was not affected. Except for very early during infection, there were not significant differences in macrophage infiltration into the CNS between WT and miR-155&minus;/&minus; JHMV-infected mice, and the severity of demyelination was similar at 14&nbsp;days p.i. between WT and miR-155&minus;/&minus; JHMV-infected mice.

Conclusions: These findings support a novel role for miR-155 in host defense in a model of viral-induced encephalomyelitis. Specifically, miR-155 enhances antiviral T cell responses including cytokine secretion, cytolytic activity, and homing to the CNS in response to viral infection. Further, miR-155 can play either a host-protective or host-damaging role during neuroinflammation depending on the disease trigger.

No MeSH data available.


Related in: MedlinePlus