Dataset Information

Overexpressing mouse model demonstrates the protective role of Muc5ac in the lungs.

ABSTRACT: MUC5AC, a major gel-forming mucin expressed in the lungs, is secreted at increased rates in response to infectious agents, implying that mucins exert a protective role against inhaled pathogens. However, epidemiological and pathological studies suggest that excessive mucin secretion causes airways obstruction and inflammation. To determine whether increased MUC5AC secretion alone produces airway obstruction and/or inflammation, we generated a mouse model overexpressing Muc5ac mRNA ~20-fold in the lungs, using the rCCSP promoter. The Muc5ac cDNA was cloned from mouse lungs and tagged internally with GFP. Bronchoalveolar lavage fluid (BALF) analysis demonstrated an approximate 18-fold increase in Muc5ac protein, which formed high-molecular-weight polymers. Histopathological studies and cell counts revealed no airway mucus obstruction or inflammation in the lungs of Muc5ac-transgenic (Muc5ac-Tg) mice. Mucus clearance was preserved, implying that the excess Muc5ac secretion produced an "expanded" rather than more concentrated mucus layer, a prediction confirmed by electron microscopy. To test whether the larger mucus barrier conferred increased protection against pathogens, Muc5ac-Tg animals were challenged with PR8/H1N1 influenza viruses and showed significant decreases in infection and neutrophilic responses. Plaque assay experiments demonstrated that Muc5ac-Tg BALF and purified Muc5ac reduced infection, likely via binding to ?2,3-linked sialic acids, consistent with influenza protection in vivo. In conclusion, the normal mucus transport and absence of a pulmonary phenotype in Muc5ac-Tg mice suggests that mucin hypersecretion alone is not sufficient to trigger luminal mucus plugging or airways inflammation/goblet cell hyperplasia. In contrast, increased Muc5ac secretion appears to exhibit a protective role against influenza infection.

SUBMITTER: Ehre C

PROVIDER: S-EPMC3478656 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Overexpressing mouse model demonstrates the protective role of Muc5ac in the lungs.

Ehre Camille C Worthington Erin N EN Liesman Rachael M RM Grubb Barbara R BR Barbier Diane D O'Neal Wanda K WK Sallenave Jean-Michel JM Pickles Raymond J RJ Boucher Richard C RC

Proceedings of the National Academy of Sciences of the United States of America 20120924 41

MUC5AC, a major gel-forming mucin expressed in the lungs, is secreted at increased rates in response to infectious agents, implying that mucins exert a protective role against inhaled pathogens. However, epidemiological and pathological studies suggest that excessive mucin secretion causes airways obstruction and inflammation. To determine whether increased MUC5AC secretion alone produces airway obstruction and/or inflammation, we generated a mouse model overexpressing Muc5ac mRNA ~20-fold in th ...[more]

PMID: 23012413

Similar Datasets

Project description:BackgroundUncontrolled T-cell activation plays a key role in systemic sclerosis (SSc). Arsenic trioxide (ATO) has immunological effects and has demonstrated potential in preclinical SSc models. In this study, we assessed the efficacy of ATO in Fra2 transgenic (Fra2TG) mice, which develop severe vascular remodeling of pulmonary arterioles and nonspecific interstitial pneumonia-like lung disease, closely resembling human SSc-associated pulmonary hypertension, therefore partially resembling to the SSc human disease.MethodsThe efficacy of ATO in Fra2TG mice was evaluated through histological scoring and determination of cell infiltration. Fibrotic changes in the lungs were assessed by measuring collagen content biochemically, using second harmonic generation to measure fibrillar collagen, and imaging via computed tomography. Cardiovascular effects were determined by measuring right ventricular systolic pressure and vessel remodeling. The mechanism of action of ATO was then investigated by analyzing lung cell infiltrates using flow cytometry and bulk RNA with sequencing techniques.ResultsAfter ATO treatment, the Ashcroft histological score was substantially decreased by 33% in ATO-treated mice compared to control mice. Other investigations of fibrotic markers showed a trend of reduction in various measurements of fibrosis, but the differences did not reach significance. Further cardiovascular investigations revealed convergent findings supporting a beneficial effect of ATO, with reduced right ventricular systolic pressure and medial wall thickness, and a significant decrease in the number of muscularized distal pulmonary arteries in ATO-treated Fra2TG mice compared to untreated Fra2TG mice. Additionally, inflammatory cell infiltration was also markedly reduced in lesioned lungs. A reduction in the frequency of CD4 + and T effector memory cells, and an increase in the percentage of CD4 + T naive cells in the lungs of ATO-treated Fra-2TG mice, was observed when compared to PBS group Fra-2Tg mice. RNA-seq analysis of ATO-treated mouse lungs revealed a downregulation of biological pathways associated with immune activity and inflammation, such as T-cell activation, regulation of leucocyte activation, leucocyte cell-cell adhesion, and regulation of lymphocyte activation.ConclusionsOur results suggest the clinical relevance of ATO treatment in SSc. Using the Fra2TG mouse model, we observed significant lung histological changes, a trend towards a decrease in various fibrotic makers, and a strong reduction in vascular remodeling. The mechanism of action of ATO appears to involve a marked counteraction of the immune activation characteristic of SSc, particularly T-cell involvement. These findings pave the way for further studies in SSc.

Project description:ObjectiveTo investigate the protective role of the sonic hedgehog (SHH) signaling associated with a lipopolysaccharide (LPS)-induced acute lung injury (ALI) in a mouse model.MethodsMale BALB/c mice were randomly divided into four groups: control, LPS, LPS-cyclopamine group and cyclopamine group. ALI was induced by LPS ip injection (5 mg/kg). The sonic hedgehog inhibitor cyclopamine (50 mg/kg) was given to the LPS-cyclopamine group at 30 min after LPS injection as well as normal mice as control. Lung injury was observed histologically in hematoxylin and eosin (HE) stained tissue sections, semi-quantified by lung tissue injury score, and the lung tissue mass alteration was measured by wet to dry weight ratio (W/D). mRNA expression levels of TNF-?, SHH, Patched (PTC) and GLI1 in lung tissue were studied with real time quantitative PCR (RT-PCR), while the protein expression of SHH and GLI1 was determined by western blot analysis.ResultsLung tissue injury score, thickness of alveolar septa, W/D, and TNF-? mRNA expression levels were significantly higher in the ALI mice than the normal mice (P<0.05). The mRNA expression levels of SHH, PTC, and GLI1 in the ALI mice were significantly higher at 12h and 24h after LPS injection, but not at the 6h time point. Protein production of SHH and GLI1 at 6h, 12h, and 24h in the lungs of ALI mice significantly increased, in a time-dependent manner, compared with that in normal mice. Cyclopamine alone has no effect on pathological changes in normal mice. Intervention with cyclopamine in ALI mice led to a reduction in mRNA levels of SHH, PTC, and GLI1 as well as SHH and GLI1 protein levels; meanwhile, the pathological injury scores of lung tissues, thickness of alveolar septa, W/D, and mRNA expression levels of TNF-? increased compared with mice receiving LPS only.ConclusionThe SHH signaling pathway was activated in response to LPS-induced ALI, and up-regulation of SHH expression could alleviate lung injury and be involved in the repair of injured lung tissue.

Dataset Information

Overexpressing mouse model demonstrates the protective role of Muc5ac in the lungs.

Publications

Overexpressing mouse model demonstrates the protective role of Muc5ac in the lungs.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets