Profiling Early Lung Immune Responses in the Mouse Model of Tuberculosis

Tuberculosis (TB) is caused by the intracellular bacteria Mycobacterium tuberculosis, and kills more than 1.5 million people every year worldwide. Immunity to TB is associated with the accumulation of IFNγ-producing T helper cell type 1 (Th1) in the lungs, activation of M.tuberculosis-infected macrophages and control of bacterial growth. However, very little is known regarding the early immune responses that mediate accumulation of activated Th1 cells in the M.tuberculosis-infected lungs. To define the induction of early immune mediators in the M.tuberculosis-infected lung, we performed mRNA profiling studies and characterized immune cells in M.tuberculosis-infected lungs at early stages of infection in the mouse model. Our data show that induction of mRNAs involved in the recognition of pathogens, expression of inflammatory cytokines, activation of APCs and generation of Th1 responses occurs between day 15 and day 21 post infection. The induction of these mRNAs coincides with cellular accumulation of Th1 cells and activation of myeloid cells in M.tuberculosis-infected lungs. Strikingly, we show the induction of mRNAs associated with Gr1+ cells, namely neutrophils and inflammatory monocytes, takes place on day 12 and coincides with cellular accumulation of Gr1+ cells in M.tuberculosis-infected lungs. Interestingly, in vivo depletion of Gr1+ neutrophils between days 10–15 results in decreased accumulation of Th1 cells on day 21 in M.tuberculosis-infected lungs without impacting overall protective outcomes. These data suggest that the recruitment of Gr1+ neutrophils is an early event that leads to production of chemokines that regulate the accumulation of Th1 cells in the M.tuberculosis-infected lungs

Clinical Outcomes of Neuromyelitis Optica with Brain Magnetic Resonance Imaging Abnormalities

Objective: To investigate clinical outcomes of neuromyelitis optica (NMO) patients with brain magnetic resonance imaging (MRI) abnormalities.Methods: One hundred and thirty-seven patients with NMO were enrolled. Clinical, laboratory, and MRI features were assessed and compared according to different distribution patterns of brain lesions.Results: The relapse number, Expanded Disability Status Scale (EDSS) score at initial diagnosis, and EDSS score at last visit were significantly higher in NMO patients with brain abnormalities than those in NMO patients without brain abnormalities, respectively. NMO patients with brainstem involvement had higher relapse number, EDSS score at initial diagnosis, and EDSS score at last visit than those without brain abnormalities or with only suprotentorial lesions.Conclusions: Appearance of brain abnormalities in the initial stage, especially brainstem involvement, might be a predictor of severe neurologic deficits and poor prognosis in NMO.</p

Induction of key immune pathways in mouse model of <i>M.tuberculosis</i> infection take places on D21 post infection.

<p>B6 mice were infected with ∼100 CFU <i>M.tuberculosis</i> via the aerosol route and at specific times after infection, lung tissue was harvested and processed to extract RNA. cDNA microarray hybridization was used to study gene expression profiles on uninfected lungs (n = 3), <i>M.tuberculosis</i>-infected lung cDNA at day 12 (D12 n = 4), day 15 (D15 n = 4) or day 21 (D21 n = 5) post infection and ingenuity signaling software was used to assess the induction of genes mainly induced on D21. Pathways induced are shown. The threshold represents 0.05 B–H adjusted p-value which was calculated from hypergeometric distribution. Longer bar represents a larger proportion of genes were enriched in a specific pathway.</p

Early recruitment of Gr1⁺ cells occurs on D12 and precedes accumulation of activated T cells.

<p>B6 mice were infected with ∼100 CFU <i>M.tuberculosis</i> via the aerosol route and at specific times after infection, cells were isolated from the lung and the percentage of Gr1⁺ neutrophils (a) or Gr1⁺ monocytes (b) were determined by flow cytometry. In some B6 <i>M.tuberculosis</i>-infected mice, lungs were fixed in 10% formalin, embedded in paraffin and the accumulation of Gr1⁺ cells (green) and CD3⁺ T cells (red) determined by immunofluorescence (c). The data points represent the mean (±SD) of values from four-five mice (a,b). _*, <i>p</i>≤0.05, _**, <i>p</i>≤0.005. _***, <i>p</i>≤0.0005 over Day 0 samples.</p

Depletion of Gr1⁺ cells between day 10–15 results in reduced Th1 responses but not impaired myeloid cell activation.

<p>B6 mice were infected with ∼100 CFU <i>M.tuberculosis</i> via the aerosol route and treated with either isotype control antibody (Isotype) or Gr1 depleting antibody between days 10–15 (D10–D15) post infection. Lung cells were isolated from antibody treated <i>M.tuberculosis</i>-infected mice and the number of total CD4⁺ CD3⁺ cells (a), number of activated CD4⁺ cells (b), percentage of activated IFNγ-producing cells (c), number of CD4⁺ CD44⁺ IFNγ-producing cells (d) was determined by flow cytometry. mRNA expression of CXCL9 in lungs of <i>M.tuberculosis</i>-infected isotype control mice or neutrophil-depleted mice was determined by RT-PCR (e). MHC Class II expression on lung DCs (f) and MHC Class II expression on lung macrophages (g) was determined in lungs of <i>M.tuberculosis</i>-infected isotype control treated mice or neutrophil-depleted mice by flow cytometry. The mean fluorescent intensity (MFI) of MHC Class II expression is shown. Lung bacterial burden from antibody-treated mice was determined by plating lung homogenates on D21 post infection (h). The data points represent the mean (±SD) of values from four-five mice (a–h). _*, <i>p</i>≤0.05_**, <i>p</i>≤0.005. _***, <i>p</i>≤0.0005 over isotype control treated <i>M.tuberculosis</i>-infected samples. ns-not significant.</p

Induction of genes associated with the TNFα pathway during early <i>M.tuberculosis</i> infection.

<p>Induction of genes associated with the TNFα pathway during early <i>M.tuberculosis</i> infection.</p

Induction of genes associated with host defense mechanisms during early <i>M.tuberculosis</i> infection.

<p>Induction of genes associated with host defense mechanisms during early <i>M.tuberculosis</i> infection.</p

Induction of genes associated with early recruitment of neutrophil and monocyte during <i>M.tuberculosis</i> infection.

<p>Induction of genes associated with early recruitment of neutrophil and monocyte during <i>M.tuberculosis</i> infection.</p

Induction of genes associated with innate host immune mechanisms during early <i>M.tuberculosis</i> infection.

<p>Induction of genes associated with innate host immune mechanisms during early <i>M.tuberculosis</i> infection.</p