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Olfactory epithelium changes in germfree mice.

François A, Grebert D, Rhimi M, Mariadassou M, Naudon L, Rabot S, Meunier N - Sci Rep (2016)

Bottom Line: These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes.Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium.As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

View Article: PubMed Central - PubMed

Affiliation: NBO, UVSQ, INRA, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.

ABSTRACT
Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

No MeSH data available.


Related in: MedlinePlus

Thinner cilia layer and reduced turn-over in the OE of germfree animals.(A1) The OE thickness was compared between conventional and germfree animals. The cilia layer thickness was evaluated based on adenylate cyclase III (ACIII) staining, whose expression is restricted to olfactory cilia. Results were expressed as mean of the OE thickness and mean of the ACIII signal area in the OE normalized to conventional animals ± SEM (n = 8). (A2,3) Representative transmission electron images of olfactory dendritic knob (white arrow) and associated cilia layer (x2000). (A4) Representative image of ACIII staining in the OE. (B1) The cellular turn-over of the OE was evaluated by quantifying the areas with cleaved caspase 3 (C3C) and PCNA stainings, taken as indices of apoptosis and proliferation levels, respectively. Results were expressed as mean of the C3C and PCNA signal area in the OE normalized to conventional animals ± SEM (n = 19). Representative image of (B2) C3C staining with OSN ongoing apoptosis and (B3) PCNA staining mainly present in basal cells same after (B2). (C) The level of proliferation was further evaluated by quantification of ki67 and PCNA expression on cDNAs from olfactory mucosa. Their expression levels were normalized to that of β-actin and are given as mean ± SEM (n = 7). (*) P < 0.05.
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f2: Thinner cilia layer and reduced turn-over in the OE of germfree animals.(A1) The OE thickness was compared between conventional and germfree animals. The cilia layer thickness was evaluated based on adenylate cyclase III (ACIII) staining, whose expression is restricted to olfactory cilia. Results were expressed as mean of the OE thickness and mean of the ACIII signal area in the OE normalized to conventional animals ± SEM (n = 8). (A2,3) Representative transmission electron images of olfactory dendritic knob (white arrow) and associated cilia layer (x2000). (A4) Representative image of ACIII staining in the OE. (B1) The cellular turn-over of the OE was evaluated by quantifying the areas with cleaved caspase 3 (C3C) and PCNA stainings, taken as indices of apoptosis and proliferation levels, respectively. Results were expressed as mean of the C3C and PCNA signal area in the OE normalized to conventional animals ± SEM (n = 19). Representative image of (B2) C3C staining with OSN ongoing apoptosis and (B3) PCNA staining mainly present in basal cells same after (B2). (C) The level of proliferation was further evaluated by quantification of ki67 and PCNA expression on cDNAs from olfactory mucosa. Their expression levels were normalized to that of β-actin and are given as mean ± SEM (n = 7). (*) P < 0.05.

Mentions: As the absence of gut microbiota impairs the development of the intestinal epithelium3, we first examined if the global anatomy of the OE was altered in germfree animals. The OE thickness (measured based on nuclear staining) was not different between germfree and conventional mice (Fig. 2A1), and transmission electron microscopy (TEM) did not reveal important changes except a thinner olfactory cilia layer in germfree animals (Fig. 2A2,3). To confirm this potential reduction in cilia layer thickness, we performed immunohistochemistry against adenylate cyclase III, a major component of the transduction pathway mainly present in the olfactory cilia16. We observed a significant decreased ACIII signal in the OE of germfree animals (Fig. 2A1,4), consistent with the thinner layer of olfactory cilia observed in TEM.


Olfactory epithelium changes in germfree mice.

François A, Grebert D, Rhimi M, Mariadassou M, Naudon L, Rabot S, Meunier N - Sci Rep (2016)

Thinner cilia layer and reduced turn-over in the OE of germfree animals.(A1) The OE thickness was compared between conventional and germfree animals. The cilia layer thickness was evaluated based on adenylate cyclase III (ACIII) staining, whose expression is restricted to olfactory cilia. Results were expressed as mean of the OE thickness and mean of the ACIII signal area in the OE normalized to conventional animals ± SEM (n = 8). (A2,3) Representative transmission electron images of olfactory dendritic knob (white arrow) and associated cilia layer (x2000). (A4) Representative image of ACIII staining in the OE. (B1) The cellular turn-over of the OE was evaluated by quantifying the areas with cleaved caspase 3 (C3C) and PCNA stainings, taken as indices of apoptosis and proliferation levels, respectively. Results were expressed as mean of the C3C and PCNA signal area in the OE normalized to conventional animals ± SEM (n = 19). Representative image of (B2) C3C staining with OSN ongoing apoptosis and (B3) PCNA staining mainly present in basal cells same after (B2). (C) The level of proliferation was further evaluated by quantification of ki67 and PCNA expression on cDNAs from olfactory mucosa. Their expression levels were normalized to that of β-actin and are given as mean ± SEM (n = 7). (*) P < 0.05.
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Related In: Results  -  Collection

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f2: Thinner cilia layer and reduced turn-over in the OE of germfree animals.(A1) The OE thickness was compared between conventional and germfree animals. The cilia layer thickness was evaluated based on adenylate cyclase III (ACIII) staining, whose expression is restricted to olfactory cilia. Results were expressed as mean of the OE thickness and mean of the ACIII signal area in the OE normalized to conventional animals ± SEM (n = 8). (A2,3) Representative transmission electron images of olfactory dendritic knob (white arrow) and associated cilia layer (x2000). (A4) Representative image of ACIII staining in the OE. (B1) The cellular turn-over of the OE was evaluated by quantifying the areas with cleaved caspase 3 (C3C) and PCNA stainings, taken as indices of apoptosis and proliferation levels, respectively. Results were expressed as mean of the C3C and PCNA signal area in the OE normalized to conventional animals ± SEM (n = 19). Representative image of (B2) C3C staining with OSN ongoing apoptosis and (B3) PCNA staining mainly present in basal cells same after (B2). (C) The level of proliferation was further evaluated by quantification of ki67 and PCNA expression on cDNAs from olfactory mucosa. Their expression levels were normalized to that of β-actin and are given as mean ± SEM (n = 7). (*) P < 0.05.
Mentions: As the absence of gut microbiota impairs the development of the intestinal epithelium3, we first examined if the global anatomy of the OE was altered in germfree animals. The OE thickness (measured based on nuclear staining) was not different between germfree and conventional mice (Fig. 2A1), and transmission electron microscopy (TEM) did not reveal important changes except a thinner olfactory cilia layer in germfree animals (Fig. 2A2,3). To confirm this potential reduction in cilia layer thickness, we performed immunohistochemistry against adenylate cyclase III, a major component of the transduction pathway mainly present in the olfactory cilia16. We observed a significant decreased ACIII signal in the OE of germfree animals (Fig. 2A1,4), consistent with the thinner layer of olfactory cilia observed in TEM.

Bottom Line: These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes.Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium.As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

View Article: PubMed Central - PubMed

Affiliation: NBO, UVSQ, INRA, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.

ABSTRACT
Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.

No MeSH data available.


Related in: MedlinePlus