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Tight junction disruption by cadmium in an in vitro human airway tissue model.

Cao X, Lin H, Muskhelishvili L, Latendresse J, Richter P, Heflich RH - Respir. Res. (2015)

Bottom Line: Noncytotoxic doses of CdCl2 resulted in the collapse of barrier function, as demonstrated by TEER measurements and Zonula occludens-1 (ZO-1) and occludin staining.Inhibition of kinase signaling using inhibitors specific for cellular Src or PKC preserved the integrity of TJs, possibly by preventing occludin tyrosine hyperphosphorylation, rather than reversing the down-regulation of the junction-interacting proteins.Our findings indicate that acute doses of Cd likely disrupt TJ integrity in human ALI airway cultures both through occludin hyperphosphorylation via kinase activation and by direct disruption of the junction-interacting complex.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The cadmium (Cd) present in air pollutants and cigarette smoke has the potential of causing multiple adverse health outcomes involving damage to pulmonary and cardiovascular tissue. Injury to pulmonary epithelium may include alterations in tight junction (TJ) integrity, resulting in impaired epithelial barrier function and enhanced penetration of chemicals and biomolecules. Herein, we investigated mechanisms involved in the disruption of TJ integrity by Cd exposure using an in vitro human air-liquid-interface (ALI) airway tissue model derived from normal primary human bronchial epithelial cells.

Methods: ALI cultures were exposed to noncytotoxic doses of CdCl2 basolaterally and TJ integrity was measured by Trans-Epithelial Electrical Resistance (TEER) and immunofluorescence staining with TJ markers. PCR array analysis was used to identify genes involved with TJ collapse. To explore the involvement of kinase signaling pathways, cultures were treated with CdCl2 in the presence of kinase inhibitors specific for cellular Src or Protein Kinase C (PKC).

Results: Noncytotoxic doses of CdCl2 resulted in the collapse of barrier function, as demonstrated by TEER measurements and Zonula occludens-1 (ZO-1) and occludin staining. CdCl2 exposure altered the expression of several groups of genes encoding proteins involved in TJ homeostasis. In particular, down-regulation of select junction-interacting proteins suggested that a possible mechanism for Cd toxicity involves disruption of the peripheral junctional complexes implicated in connecting membrane-bound TJ components to the actin cytoskeleton. Inhibition of kinase signaling using inhibitors specific for cellular Src or PKC preserved the integrity of TJs, possibly by preventing occludin tyrosine hyperphosphorylation, rather than reversing the down-regulation of the junction-interacting proteins.

Conclusions: Our findings indicate that acute doses of Cd likely disrupt TJ integrity in human ALI airway cultures both through occludin hyperphosphorylation via kinase activation and by direct disruption of the junction-interacting complex.

No MeSH data available.


Related in: MedlinePlus

Expression changes of TJ-related genes in cultures exposed basolaterally to 100 μM CdCl2. The means of the gene expression changes are plotted. All genes presented here have a fold change ≥ 1.5 and p-value < 0.05. N = 4 for vehicle-treated control group; N = 3 for 100 μM CdCl2-treated group.
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Fig5: Expression changes of TJ-related genes in cultures exposed basolaterally to 100 μM CdCl2. The means of the gene expression changes are plotted. All genes presented here have a fold change ≥ 1.5 and p-value < 0.05. N = 4 for vehicle-treated control group; N = 3 for 100 μM CdCl2-treated group.

Mentions: Genes that were differentially expressed are involved in a wide range of TJ-related biological processes, including cell surface receptors, the junction-interacting complex, G protein signaling, and protein kinase signaling (Figure 5). Nearly 40% of the genes differentially expressed by 100 μM CdCl2 were involved with the functions of the cytoplasmic junctional-protein complex. Cell surface receptors and protein kinase signaling molecules also were among the top groups of genes that were significantly modulated by Cd exposure.Figure 5


Tight junction disruption by cadmium in an in vitro human airway tissue model.

Cao X, Lin H, Muskhelishvili L, Latendresse J, Richter P, Heflich RH - Respir. Res. (2015)

Expression changes of TJ-related genes in cultures exposed basolaterally to 100 μM CdCl2. The means of the gene expression changes are plotted. All genes presented here have a fold change ≥ 1.5 and p-value < 0.05. N = 4 for vehicle-treated control group; N = 3 for 100 μM CdCl2-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4352288&req=5

Fig5: Expression changes of TJ-related genes in cultures exposed basolaterally to 100 μM CdCl2. The means of the gene expression changes are plotted. All genes presented here have a fold change ≥ 1.5 and p-value < 0.05. N = 4 for vehicle-treated control group; N = 3 for 100 μM CdCl2-treated group.
Mentions: Genes that were differentially expressed are involved in a wide range of TJ-related biological processes, including cell surface receptors, the junction-interacting complex, G protein signaling, and protein kinase signaling (Figure 5). Nearly 40% of the genes differentially expressed by 100 μM CdCl2 were involved with the functions of the cytoplasmic junctional-protein complex. Cell surface receptors and protein kinase signaling molecules also were among the top groups of genes that were significantly modulated by Cd exposure.Figure 5

Bottom Line: Noncytotoxic doses of CdCl2 resulted in the collapse of barrier function, as demonstrated by TEER measurements and Zonula occludens-1 (ZO-1) and occludin staining.Inhibition of kinase signaling using inhibitors specific for cellular Src or PKC preserved the integrity of TJs, possibly by preventing occludin tyrosine hyperphosphorylation, rather than reversing the down-regulation of the junction-interacting proteins.Our findings indicate that acute doses of Cd likely disrupt TJ integrity in human ALI airway cultures both through occludin hyperphosphorylation via kinase activation and by direct disruption of the junction-interacting complex.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The cadmium (Cd) present in air pollutants and cigarette smoke has the potential of causing multiple adverse health outcomes involving damage to pulmonary and cardiovascular tissue. Injury to pulmonary epithelium may include alterations in tight junction (TJ) integrity, resulting in impaired epithelial barrier function and enhanced penetration of chemicals and biomolecules. Herein, we investigated mechanisms involved in the disruption of TJ integrity by Cd exposure using an in vitro human air-liquid-interface (ALI) airway tissue model derived from normal primary human bronchial epithelial cells.

Methods: ALI cultures were exposed to noncytotoxic doses of CdCl2 basolaterally and TJ integrity was measured by Trans-Epithelial Electrical Resistance (TEER) and immunofluorescence staining with TJ markers. PCR array analysis was used to identify genes involved with TJ collapse. To explore the involvement of kinase signaling pathways, cultures were treated with CdCl2 in the presence of kinase inhibitors specific for cellular Src or Protein Kinase C (PKC).

Results: Noncytotoxic doses of CdCl2 resulted in the collapse of barrier function, as demonstrated by TEER measurements and Zonula occludens-1 (ZO-1) and occludin staining. CdCl2 exposure altered the expression of several groups of genes encoding proteins involved in TJ homeostasis. In particular, down-regulation of select junction-interacting proteins suggested that a possible mechanism for Cd toxicity involves disruption of the peripheral junctional complexes implicated in connecting membrane-bound TJ components to the actin cytoskeleton. Inhibition of kinase signaling using inhibitors specific for cellular Src or PKC preserved the integrity of TJs, possibly by preventing occludin tyrosine hyperphosphorylation, rather than reversing the down-regulation of the junction-interacting proteins.

Conclusions: Our findings indicate that acute doses of Cd likely disrupt TJ integrity in human ALI airway cultures both through occludin hyperphosphorylation via kinase activation and by direct disruption of the junction-interacting complex.

No MeSH data available.


Related in: MedlinePlus