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Immune Homeostasis in Epithelial Cells: Evidence and Role of Inflammasome Signaling Reviewed.

Peeters PM, Wouters EF, Reynaert NL - J Immunol Res (2015)

Bottom Line: The epithelium regulates the interaction between the noxious xenogenous, as well as the microbial environment and the immune system, not only by providing a barrier but also by expressing a number of immunoregulatory membrane receptors, and intracellular danger sensors and their downstream effectors.Amongst these are a number of inflammasome sensor subtypes, which have been initially characterized in myeloid cells and described to be activated upon assembly into multiprotein complexes by microbial and environmental triggers.This review compiles a vast amount of literature that supports a pivotal role for inflammasomes in the various epithelial barriers of the human body as essential factors maintaining immune signaling and homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Department of Respiratory Medicine, Nutrim School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, 6229 HX Maastricht, Netherlands ; IUF-Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.

ABSTRACT
The epithelium regulates the interaction between the noxious xenogenous, as well as the microbial environment and the immune system, not only by providing a barrier but also by expressing a number of immunoregulatory membrane receptors, and intracellular danger sensors and their downstream effectors. Amongst these are a number of inflammasome sensor subtypes, which have been initially characterized in myeloid cells and described to be activated upon assembly into multiprotein complexes by microbial and environmental triggers. This review compiles a vast amount of literature that supports a pivotal role for inflammasomes in the various epithelial barriers of the human body as essential factors maintaining immune signaling and homeostasis.

No MeSH data available.


Schematic representation of pseudostratified columnar epithelium of the lung indicating a variety of environmental and microbial molecules that is able to activate the inflammasome with a subsequent release of cytokines, alarmins, and growth factors.
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Related In: Results  -  Collection


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fig4: Schematic representation of pseudostratified columnar epithelium of the lung indicating a variety of environmental and microbial molecules that is able to activate the inflammasome with a subsequent release of cytokines, alarmins, and growth factors.

Mentions: To date, only a subset of inflammasomes has been described in lung epithelial cells so far (Figure 4). NLRP1 was reported to contribute to the immune response in lung epithelial cells and alveolar macrophages [25]. NLRP3 inflammasome presence and activation in lung epithelial cells was demonstrated as well [92, 93]. Of most caspase-1 activating inflammasomes that have been studied well, NLRP12 is a unique NLR that has been shown to attenuate inflammatory pathways in biochemical assays and mediates the lymph node homing of activated skin dendritic cells in contact hypersensitivity responses. Although its expression was shown in lung cells, the overall development of allergic airway disease and airway function was not significantly altered by overall NLRP12 deficiency. This suggests that NLRP12 does not play a vital role in regulating airway inflammation in this model [104]. Upon Rhinovirus pathogenesis, the contribution of NLRP3 and NLRC5 inflammasomes and IL-1β secretion in Rhinovirus pathogenesis was investigated and revealed that both inflammasomes act in a cooperative manner during the assembly by sensing intracellular Ca2+ fluxes and triggering IL-1β secretion in primary human bronchial epithelial cells [105]. Additionally, the importance of inflammasome signaling in animal models representing a cadre of lung diseases such as asthma, COPD, and acute lung injury as well as fibrosis and pneumoconiosis among others has been shown by many groups [106–114] and was recently reviewed by Brusselle et al. [115]. However no focus on the epithelium is present in any model.


Immune Homeostasis in Epithelial Cells: Evidence and Role of Inflammasome Signaling Reviewed.

Peeters PM, Wouters EF, Reynaert NL - J Immunol Res (2015)

Schematic representation of pseudostratified columnar epithelium of the lung indicating a variety of environmental and microbial molecules that is able to activate the inflammasome with a subsequent release of cytokines, alarmins, and growth factors.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4556877&req=5

fig4: Schematic representation of pseudostratified columnar epithelium of the lung indicating a variety of environmental and microbial molecules that is able to activate the inflammasome with a subsequent release of cytokines, alarmins, and growth factors.
Mentions: To date, only a subset of inflammasomes has been described in lung epithelial cells so far (Figure 4). NLRP1 was reported to contribute to the immune response in lung epithelial cells and alveolar macrophages [25]. NLRP3 inflammasome presence and activation in lung epithelial cells was demonstrated as well [92, 93]. Of most caspase-1 activating inflammasomes that have been studied well, NLRP12 is a unique NLR that has been shown to attenuate inflammatory pathways in biochemical assays and mediates the lymph node homing of activated skin dendritic cells in contact hypersensitivity responses. Although its expression was shown in lung cells, the overall development of allergic airway disease and airway function was not significantly altered by overall NLRP12 deficiency. This suggests that NLRP12 does not play a vital role in regulating airway inflammation in this model [104]. Upon Rhinovirus pathogenesis, the contribution of NLRP3 and NLRC5 inflammasomes and IL-1β secretion in Rhinovirus pathogenesis was investigated and revealed that both inflammasomes act in a cooperative manner during the assembly by sensing intracellular Ca2+ fluxes and triggering IL-1β secretion in primary human bronchial epithelial cells [105]. Additionally, the importance of inflammasome signaling in animal models representing a cadre of lung diseases such as asthma, COPD, and acute lung injury as well as fibrosis and pneumoconiosis among others has been shown by many groups [106–114] and was recently reviewed by Brusselle et al. [115]. However no focus on the epithelium is present in any model.

Bottom Line: The epithelium regulates the interaction between the noxious xenogenous, as well as the microbial environment and the immune system, not only by providing a barrier but also by expressing a number of immunoregulatory membrane receptors, and intracellular danger sensors and their downstream effectors.Amongst these are a number of inflammasome sensor subtypes, which have been initially characterized in myeloid cells and described to be activated upon assembly into multiprotein complexes by microbial and environmental triggers.This review compiles a vast amount of literature that supports a pivotal role for inflammasomes in the various epithelial barriers of the human body as essential factors maintaining immune signaling and homeostasis.

View Article: PubMed Central - PubMed

Affiliation: Department of Respiratory Medicine, Nutrim School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, 6229 HX Maastricht, Netherlands ; IUF-Leibniz Research Institute for Environmental Medicine, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.

ABSTRACT
The epithelium regulates the interaction between the noxious xenogenous, as well as the microbial environment and the immune system, not only by providing a barrier but also by expressing a number of immunoregulatory membrane receptors, and intracellular danger sensors and their downstream effectors. Amongst these are a number of inflammasome sensor subtypes, which have been initially characterized in myeloid cells and described to be activated upon assembly into multiprotein complexes by microbial and environmental triggers. This review compiles a vast amount of literature that supports a pivotal role for inflammasomes in the various epithelial barriers of the human body as essential factors maintaining immune signaling and homeostasis.

No MeSH data available.