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Identification and Characterization of Immunogenic RNA Species in HDM Allergens that Modulate Eosinophilic Lung Inflammation
Published on: May 30, 2020
Interleukin-17A mRNA and protein expression within cells from the human bronchoalveolar space after exposure to
Stefan Ivanov1, Lena Palmberg, Per Venge
1Department of Respiratory Medicine and Allergy, Institute for Internal Medicine, Göteborg University, Guldhedsgatan 10A, 413 46 Gothenburg, Sweden. Stefan.Ivanov@lungall.gu.se
Background:
In mice, the cytokine interleukin (IL)-17A causes a local accumulation of neutrophils within the bronchoalveolar space. IL-17A may thereby also contribute to an increased local proteolytic burden. In the current study, we determined whether mRNA for IL-17A is elevated and protein expression of IL-17A occurs locally in inflammatory cells within the human bronchoalveolar space during severe inflammation caused by organic dust. We also assessed the expression of the elastinolytic protease MMP-9 in this airway compartment.
Methods:
Six healthy, non-smoking human volunteers were exposed to organic dust in a swine confinement, a potent stimulus of neutrophil accumulation within the human bronchoalveolar space. Bronchoalveolar lavage (BAL) fluid was harvested 2 weeks before and 24 hours after the exposure and total and differential counts were conducted for inflammatory BAL cells. Messenger RNA for IL-17A was measured using reverse transcript polymerase chain reaction-enzyme linked immunoassay (RT-PCR-ELISA). Intracellular immunoreactivity (IR) for IL-17A and MMP-9, respectively, was determined in BAL cells.
Results:
The exposure to organic dust caused more than a forty-fold increase of mRNA for IL-17A in BAL cells. IL-17A immunoreactivity was detected mainly in BAL lymphocytes, and the number of these IL-17A expressing lymphocytes displayed an eight-fold increase, even though not statistically significant. The increase in IL-17A mRNA was associated with a substantial increase of the number of BAL neutrophils expressing MMP-9 immunoreactivity.
Conclusion:
Exposure to organic dust increases local IL-17A mRNA and because there is intracellular expression in BAL lymphocytes, this suggests that IL-17A protein can originate from lymphocytes within the human bronchoalveolar space. The fact that the increased IL-17A mRNA is associated with an increased number of MMP-9-expressing neutrophils is compatible with IL-17A increasing the local proteolytic burden through its neutrophil-accumulating effect.
Insights
Organic dust exposure significantly increases interleukin-17A (IL-17A) mRNA in the lungs, suggesting lymphocytes produce IL-17A. This correlates with increased neutrophils expressing MMP-9, potentially raising the lung
Area of Science:
- Pulmonary immunology
- Environmental health
- Protease research
Background:
- Interleukin-17A (IL-17A) induces neutrophil accumulation in mouse lungs.
- IL-17A may increase local proteolytic burden.
- Investigated IL-17A and MMP-9 in human bronchoalveolar space after organic dust exposure.
Purpose of the Study:
- Determine if IL-17A mRNA and protein are elevated in the human bronchoalveolar space following organic dust exposure.
- Assess the expression of the protease MMP-9 in this context.
Main Methods:
- Healthy volunteers exposed to organic dust.
- Bronchoalveolar lavage (BAL) fluid collected pre- and post-exposure.
- Measured IL-17A mRNA via RT-PCR-ELISA.
- Assessed intracellular IL-17A and MMP-9 immunoreactivity in BAL cells.
Main Results:
- Organic dust exposure increased IL-17A mRNA over 40-fold in BAL cells.
- IL-17A immunoreactivity found in BAL lymphocytes, with an 8-fold increase in expressing cells.
- Increased IL-17A mRNA correlated with more MMP-9 expressing neutrophils.
Conclusions:
- Organic dust exposure elevates local IL-17A mRNA in the human bronchoalveolar space.
- Lymphocytes likely produce IL-17A protein locally.
- Elevated IL-17A is associated with increased MMP-9 neutrophils, suggesting a heightened proteolytic burden.
