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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

JHMV-infected miR-155−/− mice demonstrated reduced CNS T cell infiltration. WT and miR-155−/− mice were infected i.c. with JHMV (200 PFU). Mice from each group were sacrificed 5, 7, 14, and 21 days p.i., and brains were collected. Flow analysis indicated reduced infiltration of total CD4+ T cells (a) and CD8+ T cells (c), as well as reduced virus-specific CD4+ T cells (b) and CD8+ T cells (d), as determined by tetramer staining [95, 96]. In contrast, while macrophage (CD45 + F4/80hi) infiltration into the CNS was lower in miR-155−/− mice at 5 days p.i. (e), the levels were similar at later time points. Representative spinal cords from JHMV-infected and sham-infected mice stained with LFB at day 14 p.i. showed similar levels of demyelination between infected WT mice (35.1 + 4.9 %, n = 4) and miR-155−/− mice (36.7 + 4.3, n = 4) whereas no demyelination is observed in sham-infected animals (f, g). Data presented are derived from two independent experiments with a minimum of four mice/experimental group. Data are presented as average ± SEM. Statistical significance was measured using unpaired, one-tailed Student’s T tests; *p < 0.05; **p < 0.01; ***p < 0.001
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Fig2: JHMV-infected miR-155−/− mice demonstrated reduced CNS T cell infiltration. WT and miR-155−/− mice were infected i.c. with JHMV (200 PFU). Mice from each group were sacrificed 5, 7, 14, and 21 days p.i., and brains were collected. Flow analysis indicated reduced infiltration of total CD4+ T cells (a) and CD8+ T cells (c), as well as reduced virus-specific CD4+ T cells (b) and CD8+ T cells (d), as determined by tetramer staining [95, 96]. In contrast, while macrophage (CD45 + F4/80hi) infiltration into the CNS was lower in miR-155−/− mice at 5 days p.i. (e), the levels were similar at later time points. Representative spinal cords from JHMV-infected and sham-infected mice stained with LFB at day 14 p.i. showed similar levels of demyelination between infected WT mice (35.1 + 4.9 %, n = 4) and miR-155−/− mice (36.7 + 4.3, n = 4) whereas no demyelination is observed in sham-infected animals (f, g). Data presented are derived from two independent experiments with a minimum of four mice/experimental group. Data are presented as average ± SEM. Statistical significance was measured using unpaired, one-tailed Student’s T tests; *p < 0.05; **p < 0.01; ***p < 0.001

Mentions: T cell responses are critical for controlling JHMV replication within the CNS [27, 29, 50–57]. Therefore, we next wished to determine whether increased morbidity/mortality and inability to control viral replication correlated with impaired T cell accumulation within the brains of JHMV-infected miR-155−/− mice. Brains were harvested from JHMV-infected WT or miR-155−/− mice at 5, 7, 14, and 21 days p.i., and immune cells were isolated and immunophenotyped using flow cytometry [47, 58, 59]. Both total CD4+ and virus-specific CD4+ cells were decreased in brains from miR-155−/− mice compared to WT mice at 5, 7, and 14 days p.i. (Fig. 2a, b); however, by 21 days p.i., no differences were detected. In addition, levels of total and virus-specific CD8+ cells were dramatically decreased in brains from miR-155−/− mice compared to WT mice at 5, 7, and 14 days p.i. yet not at day 21 p.i. (Fig. 2c, d). There were decreased levels of macrophages at 5 days p.i. in brains of miR-155−/− mice compared to WT mice; however, there were no significant differences in CNS macrophage accumulation at later times (Fig. 2e). The degree of demyelination at day 14 p.i. was similar between JHMV-infected WT (35.1 ± 4.9 %, n = 4) and miR-155−/− mice (36.7 % ± 4.3 %, n = 4) (Fig. 2f, g). These results demonstrate that miR-155 is necessary for optimal T cell accumulation in the CNS in the context of JHMV infection, and is consistent with previous studies.Fig. 2


MicroRNA-155 enhances T cell trafficking and antiviral effector function in a model of coronavirus-induced neurologic disease
JHMV-infected miR-155−/− mice demonstrated reduced CNS T cell infiltration. WT and miR-155−/− mice were infected i.c. with JHMV (200 PFU). Mice from each group were sacrificed 5, 7, 14, and 21 days p.i., and brains were collected. Flow analysis indicated reduced infiltration of total CD4+ T cells (a) and CD8+ T cells (c), as well as reduced virus-specific CD4+ T cells (b) and CD8+ T cells (d), as determined by tetramer staining [95, 96]. In contrast, while macrophage (CD45 + F4/80hi) infiltration into the CNS was lower in miR-155−/− mice at 5 days p.i. (e), the levels were similar at later time points. Representative spinal cords from JHMV-infected and sham-infected mice stained with LFB at day 14 p.i. showed similar levels of demyelination between infected WT mice (35.1 + 4.9 %, n = 4) and miR-155−/− mice (36.7 + 4.3, n = 4) whereas no demyelination is observed in sham-infected animals (f, g). Data presented are derived from two independent experiments with a minimum of four mice/experimental group. Data are presented as average ± SEM. Statistical significance was measured using unpaired, one-tailed Student’s T tests; *p < 0.05; **p < 0.01; ***p < 0.001
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Fig2: JHMV-infected miR-155−/− mice demonstrated reduced CNS T cell infiltration. WT and miR-155−/− mice were infected i.c. with JHMV (200 PFU). Mice from each group were sacrificed 5, 7, 14, and 21 days p.i., and brains were collected. Flow analysis indicated reduced infiltration of total CD4+ T cells (a) and CD8+ T cells (c), as well as reduced virus-specific CD4+ T cells (b) and CD8+ T cells (d), as determined by tetramer staining [95, 96]. In contrast, while macrophage (CD45 + F4/80hi) infiltration into the CNS was lower in miR-155−/− mice at 5 days p.i. (e), the levels were similar at later time points. Representative spinal cords from JHMV-infected and sham-infected mice stained with LFB at day 14 p.i. showed similar levels of demyelination between infected WT mice (35.1 + 4.9 %, n = 4) and miR-155−/− mice (36.7 + 4.3, n = 4) whereas no demyelination is observed in sham-infected animals (f, g). Data presented are derived from two independent experiments with a minimum of four mice/experimental group. Data are presented as average ± SEM. Statistical significance was measured using unpaired, one-tailed Student’s T tests; *p < 0.05; **p < 0.01; ***p < 0.001
Mentions: T cell responses are critical for controlling JHMV replication within the CNS [27, 29, 50–57]. Therefore, we next wished to determine whether increased morbidity/mortality and inability to control viral replication correlated with impaired T cell accumulation within the brains of JHMV-infected miR-155−/− mice. Brains were harvested from JHMV-infected WT or miR-155−/− mice at 5, 7, 14, and 21 days p.i., and immune cells were isolated and immunophenotyped using flow cytometry [47, 58, 59]. Both total CD4+ and virus-specific CD4+ cells were decreased in brains from miR-155−/− mice compared to WT mice at 5, 7, and 14 days p.i. (Fig. 2a, b); however, by 21 days p.i., no differences were detected. In addition, levels of total and virus-specific CD8+ cells were dramatically decreased in brains from miR-155−/− mice compared to WT mice at 5, 7, and 14 days p.i. yet not at day 21 p.i. (Fig. 2c, d). There were decreased levels of macrophages at 5 days p.i. in brains of miR-155−/− mice compared to WT mice; however, there were no significant differences in CNS macrophage accumulation at later times (Fig. 2e). The degree of demyelination at day 14 p.i. was similar between JHMV-infected WT (35.1 ± 4.9 %, n = 4) and miR-155−/− mice (36.7 % ± 4.3 %, n = 4) (Fig. 2f, g). These results demonstrate that miR-155 is necessary for optimal T cell accumulation in the CNS in the context of JHMV infection, and is consistent with previous studies.Fig. 2

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