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Gene expression profiling reveals aryl hydrocarbon receptor as a possible target for photobiomodulation when using blue light

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ABSTRACT

Photobiomodulation (PBM) with blue light induces a biphasic dose response curve in proliferation of immortalized human keratinocytes (HaCaT), with a maximum anti-proliferative effect reached with 30min (41.4 J/cm2). The aim of this study was to test the photobiomodulatory effect of 41.4 J/cm2 blue light irradiation on ROS production, apoptosis and gene expression at different time points after irradiation of HaCaT cells in vitro and assess its safety. ROS concentration was increased 30 min after irradiation. However, already 1 h after irradiation, cells were able to reduce ROS and balance the concentration to a normal level. The sudden increase in ROS did not damage the cells, which was demonstrated with FACS analysis where HaCaT cells did not show any sign of apoptosis after blue light irradiation. Furthermore, a time course could be seen in gene expression analysis after blue light, with an early response of stimulated genes already 1 h after blue light irradiation, leading to the discovery of the aryl hydrocarbon receptor as possible target for blue light irradiation.

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FACS analysis 24 h after 30 min of blue light irradiation.The four quadrants can be distinguished as follows: lower left quadrant = intact cells, lower right quadrant = early apoptosis, upper right quadrant = late apoptotic or secondary necrotic apoptotic cells and upper left quadrant = primary necrotic cells. For comparison between live and dead cells the lower left quadrant was used for the numbers of intact cells and the other three quadrants were taken together to show the amount of dead cells. In this graph there is no difference between early or late apoptosis or necrosis. 30 min of blue light did not induce apoptosis in HaCaT cells.
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f2: FACS analysis 24 h after 30 min of blue light irradiation.The four quadrants can be distinguished as follows: lower left quadrant = intact cells, lower right quadrant = early apoptosis, upper right quadrant = late apoptotic or secondary necrotic apoptotic cells and upper left quadrant = primary necrotic cells. For comparison between live and dead cells the lower left quadrant was used for the numbers of intact cells and the other three quadrants were taken together to show the amount of dead cells. In this graph there is no difference between early or late apoptosis or necrosis. 30 min of blue light did not induce apoptosis in HaCaT cells.

Mentions: Fluorescence-activated cell sorting (FACS) was applied to test a possible apoptotic effect of blue light on HaCaT cells 24 h after 30 min irradiation. Cells were labeled with Annexin V, which binds to the phospholipid membrane component phosphatidylserine on the cell surface during early apoptosis and propidiumiodide which intercalates with DNA and therefore shows late apoptosis and cell necrosis. Staurosporine treated cells served as a positive control for induced apoptosis resulting in 40% living cells and 60% dead cells. Both untreated and light-treated cells exhibited a significant difference to the positive control (p < 0.0001). Untreated as well as blue light treated cells contained ~85% living cells and ~15% dead cells. Thus, that dose of blue light did not induce apoptosis in HaCaT cells (Fig. 2).


Gene expression profiling reveals aryl hydrocarbon receptor as a possible target for photobiomodulation when using blue light
FACS analysis 24 h after 30 min of blue light irradiation.The four quadrants can be distinguished as follows: lower left quadrant = intact cells, lower right quadrant = early apoptosis, upper right quadrant = late apoptotic or secondary necrotic apoptotic cells and upper left quadrant = primary necrotic cells. For comparison between live and dead cells the lower left quadrant was used for the numbers of intact cells and the other three quadrants were taken together to show the amount of dead cells. In this graph there is no difference between early or late apoptosis or necrosis. 30 min of blue light did not induce apoptosis in HaCaT cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037386&req=5

f2: FACS analysis 24 h after 30 min of blue light irradiation.The four quadrants can be distinguished as follows: lower left quadrant = intact cells, lower right quadrant = early apoptosis, upper right quadrant = late apoptotic or secondary necrotic apoptotic cells and upper left quadrant = primary necrotic cells. For comparison between live and dead cells the lower left quadrant was used for the numbers of intact cells and the other three quadrants were taken together to show the amount of dead cells. In this graph there is no difference between early or late apoptosis or necrosis. 30 min of blue light did not induce apoptosis in HaCaT cells.
Mentions: Fluorescence-activated cell sorting (FACS) was applied to test a possible apoptotic effect of blue light on HaCaT cells 24 h after 30 min irradiation. Cells were labeled with Annexin V, which binds to the phospholipid membrane component phosphatidylserine on the cell surface during early apoptosis and propidiumiodide which intercalates with DNA and therefore shows late apoptosis and cell necrosis. Staurosporine treated cells served as a positive control for induced apoptosis resulting in 40% living cells and 60% dead cells. Both untreated and light-treated cells exhibited a significant difference to the positive control (p < 0.0001). Untreated as well as blue light treated cells contained ~85% living cells and ~15% dead cells. Thus, that dose of blue light did not induce apoptosis in HaCaT cells (Fig. 2).

View Article: PubMed Central - PubMed

ABSTRACT

Photobiomodulation (PBM) with blue light induces a biphasic dose response curve in proliferation of immortalized human keratinocytes (HaCaT), with a maximum anti-proliferative effect reached with 30min (41.4&thinsp;J/cm2). The aim of this study was to test the photobiomodulatory effect of 41.4&thinsp;J/cm2 blue light irradiation on ROS production, apoptosis and gene expression at different time points after irradiation of HaCaT cells in vitro and assess its safety. ROS concentration was increased 30&thinsp;min after irradiation. However, already 1&thinsp;h after irradiation, cells were able to reduce ROS and balance the concentration to a normal level. The sudden increase in ROS did not damage the cells, which was demonstrated with FACS analysis where HaCaT cells did not show any sign of apoptosis after blue light irradiation. Furthermore, a time course could be seen in gene expression analysis after blue light, with an early response of stimulated genes already 1&thinsp;h after blue light irradiation, leading to the discovery of the aryl hydrocarbon receptor as possible target for blue light irradiation.

No MeSH data available.


Related in: MedlinePlus