Interleukin-11 Drives Early Lung Inflammation during Mycobacterium tuberculosis Infection in Genetically Susceptible Mice

IL-11 is multifunctional cytokine whose physiological role in the lungs during pulmonary tuberculosis (TB) is poorly understood. Here, using in vivo administration of specific antibodies against IL-11, we demonstrate for the first time that blocking IL-11 diminishes histopathology and neutrophilic infiltration of the lung tissue in TB-infected genetically susceptible mice. Antibody treatment decreased the pulmonary levels of IL-11 and other key inflammatory cytokines not belonging to the Th1 axis, and down-regulated IL-11 mRNA expression. This suggests the existence of a positive feedback loop at the transcriptional level, which is further supported by up-regulation of IL-11 mRNA expression in the presence of rIL-11 in in vitro cultures of lung cells. These findings imply a pathogenic role for IL-11 during the early phase of Mycobacterium tuberculosis-triggered disease in a genetically susceptible host

MicroRNAs as Biomarkers of Active Pulmonary TB Course

The spread of drug-resistant forms of TB dictates the need for surgical treatment in the complex of anti-tuberculosis measures in Russia. Most often, surgical intervention is performed in the case of pulmonary tuberculoma or fibrotic cavitary tuberculosis (FCT). This study is devoted to the search for biomarkers that characterize the course of disease in surgical TB patients. It is assumed that such biomarkers will help the surgeon decide on the timing of the planned operation. A number of serum microRNAs, potential regulators of inflammation and fibrosis in TB, selected on the basis of PCR-Array analysis, were considered as biomarkers. Quantitative real time polymerase chain reaction and receiver operating curves (ROC) were used to verify Array data and to estimate the ability of microRNAs (miRNAs) to discriminate between healthy controls, tuberculoma patients, and FCT patients. The study showed that miR-155, miR-191 and miR-223 were differentially expressed in serum of tuberculoma with “decay” and tuberculoma without “decay” patients. Another combination (miR-26a, miR-191, miR-222 and miR-320) forms a set to differentiate between tuberculoma with “decay” and FCT. Patients with tuberculoma without “decay” diagnosis differ from those with FCT in serum expression of miR-26a, miR-155, miR-191, miR-222 and miR-223. Further investigations are required to evaluate these sets on a larger population so as to set cut-off values that could be applied in laboratory diagnosis

Protein levels of IL-11 affect IL-11 mRNA expression.

<p>(A) <i>In vivo</i> administration of anti-IL-11 antibodies leads to a selective down-regulation of IL-11 mRNA. The level of expression was quantified in 5 individual mice per group, using qrt-PCR and normalization against the level of GAPDH expression. Results obtained in 1 of 2 similar experiments are expressed as mean ± SEM (for IL-11 expression <i>P</i> = 0.021, for other cytokines <i>P</i>>0.05). (B) Introduction of 100 ng/ml rIL-11 in cultures of lung cells up-regulates the expression of IL-11 mRNA. Results of two similar experiments are expressed as mean of 3 wells ± SEM (<i>P</i><0.01, ANOVA, compared to negative controls and cultures stimulated with 10 ng/ml IL-11).</p

Treatment with anti-IL-11 antibodies significantly attenuates the severity of TB in I/St mice.

<p>(A) ∼3-fold decrease in lung CFU counts compared to control animals. (B and C) Lung pathology in individual animals. None of anti-IL-11-treated mice developed necrotic TB foci evident in control mice <i>a</i>, <i>d</i> and <i>g</i> (circled). (D) Statistical evaluation of the proportion of inflamed lung tissue. CFU counts and morphometry were performed in all mice included in 2 independent experiments (total N = 16 and 17 for experimental and control groups, respectively). Histology is displayed for individual mice analyzed in one experiment (N = 7 for each group).</p

Properties of anti-IL-11 polyclonal antibodies.

<p>(A) Reactivity of affinity purified rabbit globulin preparation against mIL-11 assessed in ELISA format. No reactivity was found in pre-immune globulin (diamonds); immunoglobulin from rabbits immunized thrice with rmIL-11 showed very strong reactivity (squares); after exhaustion on mycobacterial sonicate adsorbent, specific anti-IL-11 reactivity dropped but was readily detected (triangles). (B) Immune blotting with rmIL-11 with polyclonal rabbit anti-mIL-11 antibodies (preparation identical to one displayed as triangles in (A). Tracks: 1, 2 – immune rabbits 1 and 2; 3, 4 – pre-immune rabbits 1 and 2; 5 – conjugate-free control.</p

Two weeks after TB challenge the level of IL-11 mRNA increases ∼1 log in the lungs of TB-susceptible I/St but does not change in TB-resistant A/Sn mice.

<p>Mean ± SEM expression level plotted against that of GABDT in 4 individual mice per group is displayed (<i>P</i><0.01, ANOVA, between naïve and infected I/St mice).</p

Anti-IL-11 antibody therapy decreases levels of IL-11 and pro-inflammatory factors in the lung tissue without shifting the IL-12 – IFN-γ/IL-10 balance.

<p>Cytokine contents in lung homogenates were assessed by ELISA for 4 mice in each group. The results of one of two similar experiments are displayed as mean ± SEM.</p