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Methanosphaera stadtmanae induces a type IV hypersensitivity response in a mouse model of airway inflammation

View Article: PubMed Central - PubMed

ABSTRACT

Despite improved awareness of work‐related diseases and preventive measures, many workers are still at high risk of developing occupational hypersensitivity airway diseases. This stems from a lack of knowledge of bioaerosol composition and their potential effects on human health. Recently, archaea species were identified in bioaerosols, raising the possibility that they play a major role in exposure‐related pathology. Specifically, Methanosphaera stadtmanae (MSS) and Methanobrevibacter smithii (MBS) are found in high concentrations in agricultural environments and respiratory exposure to crude extract demonstrates immunomodulatory activity in mice. Nevertheless, our knowledge of the specific impact of methanogens exposure on airway immunity and their potential to induce airway hypersensitivity responses in workers remains scant. Analysis of the lung mucosal response to methanogen crude extracts in mice demonstrated that MSS and MBS predominantly induced TH17 airway inflammation, typical of a type IV hypersensitivity response. Furthermore, the response to MSS was associated with antigen‐specific IgG1 and IgG2a production. However, despite the presence of eosinophils after MSS exposure, only a weak TH2 response and no airway hyperresponsiveness were observed. Finally, using eosinophil and mast cell‐deficient mice, we confirmed that these cells are dispensable for the TH17 response to MSS, although eosinophils likely contribute to the exacerbation of inflammatory processes induced by MSS crude extract exposure. We conclude that, as MSS induces a clear type IV hypersensitivity lung response, it has the potential to be harmful to workers frequently exposed to this methanogen, and that preventive measures should be taken to avoid chronic hypersensitivity disease development in workers.

No MeSH data available.


Related in: MedlinePlus

MSS induces a mixed TH2/TH17 immune lung response. (A) Timeline of the model of exposure to methanogens. Full line represents intranasal instillation of either PBS, MSS or MBS crude extract while dashed line represents day of euthanasia. (B) Flow cytometry gating strategy for the polarity of the effector lung response after ex‐vivo stimulation of lung leukocytes isolated from methanogen‐exposed mice. CD4+ T cells were gated from total lung cells and cytokine‐positive cells were analyzed using Fluorescence Minus One (FMO) controls. (C) Severity of the inflammatory lung response after 3 μg MSS exposure was measured using total broncho‐alveolar lavage (BAL) count and differential count. (D) Polarity of the effector response evaluated as number and the % of CD4+ cells expressing IFNg, IL‐13 or IL‐17A. (E) Il13 and Il17a expression measured by qRT‐PCR on lung tissue of mice exposed to MSS compared with PBS. (F) MSS‐specific IgG1 and IgG2a and total IgE production was measured from serum using ELISA. Results are representative of at least three separate experiments; n = 3–6 mice/group. * = P ˂ 0.05.
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phy213163-fig-0001: MSS induces a mixed TH2/TH17 immune lung response. (A) Timeline of the model of exposure to methanogens. Full line represents intranasal instillation of either PBS, MSS or MBS crude extract while dashed line represents day of euthanasia. (B) Flow cytometry gating strategy for the polarity of the effector lung response after ex‐vivo stimulation of lung leukocytes isolated from methanogen‐exposed mice. CD4+ T cells were gated from total lung cells and cytokine‐positive cells were analyzed using Fluorescence Minus One (FMO) controls. (C) Severity of the inflammatory lung response after 3 μg MSS exposure was measured using total broncho‐alveolar lavage (BAL) count and differential count. (D) Polarity of the effector response evaluated as number and the % of CD4+ cells expressing IFNg, IL‐13 or IL‐17A. (E) Il13 and Il17a expression measured by qRT‐PCR on lung tissue of mice exposed to MSS compared with PBS. (F) MSS‐specific IgG1 and IgG2a and total IgE production was measured from serum using ELISA. Results are representative of at least three separate experiments; n = 3–6 mice/group. * = P ˂ 0.05.

Mentions: The timeline used for the chronic model is presented in Figure 1A. Mice were anesthetized with isoflurane and received intranasal instillations (i.n.) of either 3 μg or 100 μg of MSS crude extract or 6.25 μg of MBS crude extract on three consecutive days/week for 3 weeks. Mice were euthanized 4 days after the last exposure. Upon euthanasia, mice were tracheotomized with an 18G catheter, and a broncho‐alveolar lavage (BAL) was performed via three separate injections/aspirations of 1 mL saline. Total BAL cells were counted and differential counts obtained using Giemsa stain (HemaStain Set, Fisher Scientific, Kalamazoo, MI). For the administration of anti‐IL‐17A, mice received 50 μg of anti‐IL‐17A or isotype control antibodies (Bio X Cell, West Lebanon, NH) intra‐peritoneally (i.p.) 1 h prior to each MSS i.n. exposure.


Methanosphaera stadtmanae induces a type IV hypersensitivity response in a mouse model of airway inflammation
MSS induces a mixed TH2/TH17 immune lung response. (A) Timeline of the model of exposure to methanogens. Full line represents intranasal instillation of either PBS, MSS or MBS crude extract while dashed line represents day of euthanasia. (B) Flow cytometry gating strategy for the polarity of the effector lung response after ex‐vivo stimulation of lung leukocytes isolated from methanogen‐exposed mice. CD4+ T cells were gated from total lung cells and cytokine‐positive cells were analyzed using Fluorescence Minus One (FMO) controls. (C) Severity of the inflammatory lung response after 3 μg MSS exposure was measured using total broncho‐alveolar lavage (BAL) count and differential count. (D) Polarity of the effector response evaluated as number and the % of CD4+ cells expressing IFNg, IL‐13 or IL‐17A. (E) Il13 and Il17a expression measured by qRT‐PCR on lung tissue of mice exposed to MSS compared with PBS. (F) MSS‐specific IgG1 and IgG2a and total IgE production was measured from serum using ELISA. Results are representative of at least three separate experiments; n = 3–6 mice/group. * = P ˂ 0.05.
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phy213163-fig-0001: MSS induces a mixed TH2/TH17 immune lung response. (A) Timeline of the model of exposure to methanogens. Full line represents intranasal instillation of either PBS, MSS or MBS crude extract while dashed line represents day of euthanasia. (B) Flow cytometry gating strategy for the polarity of the effector lung response after ex‐vivo stimulation of lung leukocytes isolated from methanogen‐exposed mice. CD4+ T cells were gated from total lung cells and cytokine‐positive cells were analyzed using Fluorescence Minus One (FMO) controls. (C) Severity of the inflammatory lung response after 3 μg MSS exposure was measured using total broncho‐alveolar lavage (BAL) count and differential count. (D) Polarity of the effector response evaluated as number and the % of CD4+ cells expressing IFNg, IL‐13 or IL‐17A. (E) Il13 and Il17a expression measured by qRT‐PCR on lung tissue of mice exposed to MSS compared with PBS. (F) MSS‐specific IgG1 and IgG2a and total IgE production was measured from serum using ELISA. Results are representative of at least three separate experiments; n = 3–6 mice/group. * = P ˂ 0.05.
Mentions: The timeline used for the chronic model is presented in Figure 1A. Mice were anesthetized with isoflurane and received intranasal instillations (i.n.) of either 3 μg or 100 μg of MSS crude extract or 6.25 μg of MBS crude extract on three consecutive days/week for 3 weeks. Mice were euthanized 4 days after the last exposure. Upon euthanasia, mice were tracheotomized with an 18G catheter, and a broncho‐alveolar lavage (BAL) was performed via three separate injections/aspirations of 1 mL saline. Total BAL cells were counted and differential counts obtained using Giemsa stain (HemaStain Set, Fisher Scientific, Kalamazoo, MI). For the administration of anti‐IL‐17A, mice received 50 μg of anti‐IL‐17A or isotype control antibodies (Bio X Cell, West Lebanon, NH) intra‐peritoneally (i.p.) 1 h prior to each MSS i.n. exposure.

View Article: PubMed Central - PubMed

ABSTRACT

Despite improved awareness of work‐related diseases and preventive measures, many workers are still at high risk of developing occupational hypersensitivity airway diseases. This stems from a lack of knowledge of bioaerosol composition and their potential effects on human health. Recently, archaea species were identified in bioaerosols, raising the possibility that they play a major role in exposure‐related pathology. Specifically, Methanosphaera stadtmanae (MSS) and Methanobrevibacter smithii (MBS) are found in high concentrations in agricultural environments and respiratory exposure to crude extract demonstrates immunomodulatory activity in mice. Nevertheless, our knowledge of the specific impact of methanogens exposure on airway immunity and their potential to induce airway hypersensitivity responses in workers remains scant. Analysis of the lung mucosal response to methanogen crude extracts in mice demonstrated that MSS and MBS predominantly induced TH17 airway inflammation, typical of a type IV hypersensitivity response. Furthermore, the response to MSS was associated with antigen‐specific IgG1 and IgG2a production. However, despite the presence of eosinophils after MSS exposure, only a weak TH2 response and no airway hyperresponsiveness were observed. Finally, using eosinophil and mast cell‐deficient mice, we confirmed that these cells are dispensable for the TH17 response to MSS, although eosinophils likely contribute to the exacerbation of inflammatory processes induced by MSS crude extract exposure. We conclude that, as MSS induces a clear type IV hypersensitivity lung response, it has the potential to be harmful to workers frequently exposed to this methanogen, and that preventive measures should be taken to avoid chronic hypersensitivity disease development in workers.

No MeSH data available.


Related in: MedlinePlus