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Antagonism of miR-328 increases the antimicrobial function of macrophages and neutrophils and rapid clearance of non-typeable Haemophilus influenzae (NTHi) from infected lung.

Tay HL, Kaiko GE, Plank M, Li J, Maltby S, Essilfie AT, Jarnicki A, Yang M, Mattes J, Hansbro PM, Foster PS - PLoS Pathog. (2015)

Bottom Line: Manipulation miRNA directly regulating anti-microbial machinery of the innate immune system may boost host defence responses.Here we demonstrate that miR-328 is a key element of the host response to pulmonary infection with non-typeable haemophilus influenzae and pharmacological inhibition in mouse and human macrophages augments phagocytosis, the production of reactive oxygen species, and microbicidal activity.Thus, miRNA pathways can be targeted in the lung to enhance host defence against a clinically relevant microbial infection and offer a potential new anti-microbial approach for the treatment of respiratory diseases.

View Article: PubMed Central - PubMed

Affiliation: Priority Research Centre for Asthma and Respiratory Disease, Department of Microbiology and Immunology, School of Pharmacy and Biomedical Sciences, Faculty of Health and Hunter Medical Research Institute, University of Newcastle, Newcastle, Australia.

ABSTRACT
Pathogenic bacterial infections of the lung are life threatening and underpin chronic lung diseases. Current treatments are often ineffective potentially due to increasing antibiotic resistance and impairment of innate immunity by disease processes and steroid therapy. Manipulation miRNA directly regulating anti-microbial machinery of the innate immune system may boost host defence responses. Here we demonstrate that miR-328 is a key element of the host response to pulmonary infection with non-typeable haemophilus influenzae and pharmacological inhibition in mouse and human macrophages augments phagocytosis, the production of reactive oxygen species, and microbicidal activity. Moreover, inhibition of miR-328 in respiratory models of infection, steroid-induced immunosuppression, and smoke-induced emphysema enhances bacterial clearance. Thus, miRNA pathways can be targeted in the lung to enhance host defence against a clinically relevant microbial infection and offer a potential new anti-microbial approach for the treatment of respiratory diseases.

No MeSH data available.


Related in: MedlinePlus

Inhibiting miR-328 enhances bacterial clearance in dexamethasone-mediated immune suppressed mice.(A-C) Mice were treated with vehicle or dexamethasone (i.p.) for 3 consecutive days before being challenged with NTHi (i.t.) for 18hr. (D-F) Mice were treated with antagomir or scrambled control 6 h post inoculation. (A, D) MiR-328 expression was determined using Taqman PCR, normalised to sno-202 and expressed as fold change compared to vehicle and scrambled control groups. (B, E) bacterial load in the lungs was measured by plating and colony counting lung homogenates, and (C, F) BAL fluid was collected, cells isolated by cytospin and stained, and the total cellular infiltrate was assessed. Results are expressed as mean ± SEM (n = 7–12 mice per group; * p<0.05, ** p<0.01, *** p<0.001 as indicated on the graphs).
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ppat.1004549.g004: Inhibiting miR-328 enhances bacterial clearance in dexamethasone-mediated immune suppressed mice.(A-C) Mice were treated with vehicle or dexamethasone (i.p.) for 3 consecutive days before being challenged with NTHi (i.t.) for 18hr. (D-F) Mice were treated with antagomir or scrambled control 6 h post inoculation. (A, D) MiR-328 expression was determined using Taqman PCR, normalised to sno-202 and expressed as fold change compared to vehicle and scrambled control groups. (B, E) bacterial load in the lungs was measured by plating and colony counting lung homogenates, and (C, F) BAL fluid was collected, cells isolated by cytospin and stained, and the total cellular infiltrate was assessed. Results are expressed as mean ± SEM (n = 7–12 mice per group; * p<0.05, ** p<0.01, *** p<0.001 as indicated on the graphs).

Mentions: We next determined whether miR-328 was involved in dexamethasone-mediated suppression of immunity and bacterial clearance, and if inhibition of this miRNA could enhance bacterial clearance in these immune suppressed mice. Mice were administered dexamethasone i.p. daily for 3 days and were then inoculated with NTHi (scheme Fig 4). Dexamethasone treatment did not alter miR-328 expression, suggesting that this miRNA was not directly involved in mediating the effects of corticosteroids (Fig 4A). As expected, dexamethasone pre-treated mice inoculated with NTHi had substantially increased bacterial load in their lungs during infection (Fig 4B). Interestingly, pre-treatment also increased the inflammatory cell infiltrate in the lungs. This is likely due to the increased bacterial load, which results in a greater proinflammatory response leading to the recruitment of more inflammatory cells (Fig 4C). Ant-328 treatment inhibited miR-328 in both dexamethasone and vehicle-treated mice infected with NTHi to similar levels (Fig 4D). Inhibition of miR-328 in dexamethasone pre-treated mice reversed the increased bacteria load compared to controls (Fig 4E). Importantly, bacterial levels were reduced to below those in non-immune-suppressed mice (vehicle+Scr control), and to equivalent levels compared to non-immune suppressed mice treated with ant-328 (vehicle+ant-328). These data indicate that the inhibition of miR-328 was as effective at clearing bacteria in both immune competent and immune suppressed environments. Again the number of infiltrating inflammatory cells in the BAL was only increased by dexamethasone treatment and there was no difference between Scr control and the ant-328 treated groups (Fig 4F).


Antagonism of miR-328 increases the antimicrobial function of macrophages and neutrophils and rapid clearance of non-typeable Haemophilus influenzae (NTHi) from infected lung.

Tay HL, Kaiko GE, Plank M, Li J, Maltby S, Essilfie AT, Jarnicki A, Yang M, Mattes J, Hansbro PM, Foster PS - PLoS Pathog. (2015)

Inhibiting miR-328 enhances bacterial clearance in dexamethasone-mediated immune suppressed mice.(A-C) Mice were treated with vehicle or dexamethasone (i.p.) for 3 consecutive days before being challenged with NTHi (i.t.) for 18hr. (D-F) Mice were treated with antagomir or scrambled control 6 h post inoculation. (A, D) MiR-328 expression was determined using Taqman PCR, normalised to sno-202 and expressed as fold change compared to vehicle and scrambled control groups. (B, E) bacterial load in the lungs was measured by plating and colony counting lung homogenates, and (C, F) BAL fluid was collected, cells isolated by cytospin and stained, and the total cellular infiltrate was assessed. Results are expressed as mean ± SEM (n = 7–12 mice per group; * p<0.05, ** p<0.01, *** p<0.001 as indicated on the graphs).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4404141&req=5

ppat.1004549.g004: Inhibiting miR-328 enhances bacterial clearance in dexamethasone-mediated immune suppressed mice.(A-C) Mice were treated with vehicle or dexamethasone (i.p.) for 3 consecutive days before being challenged with NTHi (i.t.) for 18hr. (D-F) Mice were treated with antagomir or scrambled control 6 h post inoculation. (A, D) MiR-328 expression was determined using Taqman PCR, normalised to sno-202 and expressed as fold change compared to vehicle and scrambled control groups. (B, E) bacterial load in the lungs was measured by plating and colony counting lung homogenates, and (C, F) BAL fluid was collected, cells isolated by cytospin and stained, and the total cellular infiltrate was assessed. Results are expressed as mean ± SEM (n = 7–12 mice per group; * p<0.05, ** p<0.01, *** p<0.001 as indicated on the graphs).
Mentions: We next determined whether miR-328 was involved in dexamethasone-mediated suppression of immunity and bacterial clearance, and if inhibition of this miRNA could enhance bacterial clearance in these immune suppressed mice. Mice were administered dexamethasone i.p. daily for 3 days and were then inoculated with NTHi (scheme Fig 4). Dexamethasone treatment did not alter miR-328 expression, suggesting that this miRNA was not directly involved in mediating the effects of corticosteroids (Fig 4A). As expected, dexamethasone pre-treated mice inoculated with NTHi had substantially increased bacterial load in their lungs during infection (Fig 4B). Interestingly, pre-treatment also increased the inflammatory cell infiltrate in the lungs. This is likely due to the increased bacterial load, which results in a greater proinflammatory response leading to the recruitment of more inflammatory cells (Fig 4C). Ant-328 treatment inhibited miR-328 in both dexamethasone and vehicle-treated mice infected with NTHi to similar levels (Fig 4D). Inhibition of miR-328 in dexamethasone pre-treated mice reversed the increased bacteria load compared to controls (Fig 4E). Importantly, bacterial levels were reduced to below those in non-immune-suppressed mice (vehicle+Scr control), and to equivalent levels compared to non-immune suppressed mice treated with ant-328 (vehicle+ant-328). These data indicate that the inhibition of miR-328 was as effective at clearing bacteria in both immune competent and immune suppressed environments. Again the number of infiltrating inflammatory cells in the BAL was only increased by dexamethasone treatment and there was no difference between Scr control and the ant-328 treated groups (Fig 4F).

Bottom Line: Manipulation miRNA directly regulating anti-microbial machinery of the innate immune system may boost host defence responses.Here we demonstrate that miR-328 is a key element of the host response to pulmonary infection with non-typeable haemophilus influenzae and pharmacological inhibition in mouse and human macrophages augments phagocytosis, the production of reactive oxygen species, and microbicidal activity.Thus, miRNA pathways can be targeted in the lung to enhance host defence against a clinically relevant microbial infection and offer a potential new anti-microbial approach for the treatment of respiratory diseases.

View Article: PubMed Central - PubMed

Affiliation: Priority Research Centre for Asthma and Respiratory Disease, Department of Microbiology and Immunology, School of Pharmacy and Biomedical Sciences, Faculty of Health and Hunter Medical Research Institute, University of Newcastle, Newcastle, Australia.

ABSTRACT
Pathogenic bacterial infections of the lung are life threatening and underpin chronic lung diseases. Current treatments are often ineffective potentially due to increasing antibiotic resistance and impairment of innate immunity by disease processes and steroid therapy. Manipulation miRNA directly regulating anti-microbial machinery of the innate immune system may boost host defence responses. Here we demonstrate that miR-328 is a key element of the host response to pulmonary infection with non-typeable haemophilus influenzae and pharmacological inhibition in mouse and human macrophages augments phagocytosis, the production of reactive oxygen species, and microbicidal activity. Moreover, inhibition of miR-328 in respiratory models of infection, steroid-induced immunosuppression, and smoke-induced emphysema enhances bacterial clearance. Thus, miRNA pathways can be targeted in the lung to enhance host defence against a clinically relevant microbial infection and offer a potential new anti-microbial approach for the treatment of respiratory diseases.

No MeSH data available.


Related in: MedlinePlus