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Toll-like receptor 3 activation is required for normal skin barrier repair following UV damage.

Borkowski AW, Kuo IH, Bernard JJ, Yoshida T, Williams MR, Hung NJ, Yu BD, Beck LA, Gallo RL - J. Invest. Dermatol. (2014)

Bottom Line: UV damage to the skin leads to the release of noncoding RNA (ncRNA) from necrotic keratinocytes that activates Toll-like receptor 3 (TLR3).This release of ncRNA triggers inflammation in the skin following UV damage.Combined, these data further validate the conclusion that recognition of endogenous RNA by TLR3 is an important step in the program of skin barrier repair.

View Article: PubMed Central - PubMed

Affiliation: Division of Dermatology, Department of Medicine, University of California, San Diego, La Jolla, California, USA.

ABSTRACT
UV damage to the skin leads to the release of noncoding RNA (ncRNA) from necrotic keratinocytes that activates Toll-like receptor 3 (TLR3). This release of ncRNA triggers inflammation in the skin following UV damage. Recently, TLR3 activation was also shown to aid wound repair and increase the expression of genes associated with permeability barrier repair. Here, we sought to test whether skin barrier repair after UVB damage is dependent on the activation of TLR3. We observed that multiple ncRNAs induced expression of skin barrier repair genes, that the TLR3 ligand Poly (I:C) also induced expression and function of tight junctions, and that the ncRNA U1 acts in a TLR3-dependent manner to induce expression of skin barrier repair genes. These observations were shown to have functional relevance as Tlr3-/- mice displayed a delay in skin barrier repair following UVB damage. Combined, these data further validate the conclusion that recognition of endogenous RNA by TLR3 is an important step in the program of skin barrier repair.

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Related in: MedlinePlus

Poly (I:C)-treatment increases tight junction function in keratinocytesTransepithelial electrical resistance (TEER) was measured in confluent differentiated primary human keratinocytes grown in transwell inserts that were treated with various concentrations of Poly (I:C) for 24 hours (a) and 48 hours (b). (c) Time course data of TEER values. (d) Paracellular flux was measured 30 minutes after addition of fluorescein sodium to differentiated keratinocytes that were treated with various concentrations of Poly (I:C) for 48 hours. Data are mean +/− SEM, n = 3–8, and are representative of at least three independent experiments. * = P < 0.05, ** = P < 0.01, *** = P < 0.001. One-tailed t-test.
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Figure 2: Poly (I:C)-treatment increases tight junction function in keratinocytesTransepithelial electrical resistance (TEER) was measured in confluent differentiated primary human keratinocytes grown in transwell inserts that were treated with various concentrations of Poly (I:C) for 24 hours (a) and 48 hours (b). (c) Time course data of TEER values. (d) Paracellular flux was measured 30 minutes after addition of fluorescein sodium to differentiated keratinocytes that were treated with various concentrations of Poly (I:C) for 48 hours. Data are mean +/− SEM, n = 3–8, and are representative of at least three independent experiments. * = P < 0.05, ** = P < 0.01, *** = P < 0.001. One-tailed t-test.

Mentions: As we observed increased mRNA for genes associated with tight junctions following treatment of NHEK cultures with both Poly (I:C) and UVB-damaged NHEK products, we next evaluated the function of tight junctions in response to dsRNA. In this set of experiments, NHEK were grown to confluence in normal keratinocyte media in 24-well inserts prior to being differentiated (De Benedetto et al. 2011; Kuo et al. 2013). Differentiating, partially stratified keratinocytes were then treated with Poly (I:C) and transepithelial electrical resistance (TEER) values were measured using an EVOMX voltohmmeter (World Precision Instruments, Sarasota, FL). We observed that Poly (I:C) treatment led to dose-dependent increases in TEER readings at 24 and 48 hours after treatment (Figure 2a and 2b). The initial increase in TEER values stimulated by Poly (I:C) diminished over time and was no longer significantly different than control samples by day 4 (Figure 2c).


Toll-like receptor 3 activation is required for normal skin barrier repair following UV damage.

Borkowski AW, Kuo IH, Bernard JJ, Yoshida T, Williams MR, Hung NJ, Yu BD, Beck LA, Gallo RL - J. Invest. Dermatol. (2014)

Poly (I:C)-treatment increases tight junction function in keratinocytesTransepithelial electrical resistance (TEER) was measured in confluent differentiated primary human keratinocytes grown in transwell inserts that were treated with various concentrations of Poly (I:C) for 24 hours (a) and 48 hours (b). (c) Time course data of TEER values. (d) Paracellular flux was measured 30 minutes after addition of fluorescein sodium to differentiated keratinocytes that were treated with various concentrations of Poly (I:C) for 48 hours. Data are mean +/− SEM, n = 3–8, and are representative of at least three independent experiments. * = P < 0.05, ** = P < 0.01, *** = P < 0.001. One-tailed t-test.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4289479&req=5

Figure 2: Poly (I:C)-treatment increases tight junction function in keratinocytesTransepithelial electrical resistance (TEER) was measured in confluent differentiated primary human keratinocytes grown in transwell inserts that were treated with various concentrations of Poly (I:C) for 24 hours (a) and 48 hours (b). (c) Time course data of TEER values. (d) Paracellular flux was measured 30 minutes after addition of fluorescein sodium to differentiated keratinocytes that were treated with various concentrations of Poly (I:C) for 48 hours. Data are mean +/− SEM, n = 3–8, and are representative of at least three independent experiments. * = P < 0.05, ** = P < 0.01, *** = P < 0.001. One-tailed t-test.
Mentions: As we observed increased mRNA for genes associated with tight junctions following treatment of NHEK cultures with both Poly (I:C) and UVB-damaged NHEK products, we next evaluated the function of tight junctions in response to dsRNA. In this set of experiments, NHEK were grown to confluence in normal keratinocyte media in 24-well inserts prior to being differentiated (De Benedetto et al. 2011; Kuo et al. 2013). Differentiating, partially stratified keratinocytes were then treated with Poly (I:C) and transepithelial electrical resistance (TEER) values were measured using an EVOMX voltohmmeter (World Precision Instruments, Sarasota, FL). We observed that Poly (I:C) treatment led to dose-dependent increases in TEER readings at 24 and 48 hours after treatment (Figure 2a and 2b). The initial increase in TEER values stimulated by Poly (I:C) diminished over time and was no longer significantly different than control samples by day 4 (Figure 2c).

Bottom Line: UV damage to the skin leads to the release of noncoding RNA (ncRNA) from necrotic keratinocytes that activates Toll-like receptor 3 (TLR3).This release of ncRNA triggers inflammation in the skin following UV damage.Combined, these data further validate the conclusion that recognition of endogenous RNA by TLR3 is an important step in the program of skin barrier repair.

View Article: PubMed Central - PubMed

Affiliation: Division of Dermatology, Department of Medicine, University of California, San Diego, La Jolla, California, USA.

ABSTRACT
UV damage to the skin leads to the release of noncoding RNA (ncRNA) from necrotic keratinocytes that activates Toll-like receptor 3 (TLR3). This release of ncRNA triggers inflammation in the skin following UV damage. Recently, TLR3 activation was also shown to aid wound repair and increase the expression of genes associated with permeability barrier repair. Here, we sought to test whether skin barrier repair after UVB damage is dependent on the activation of TLR3. We observed that multiple ncRNAs induced expression of skin barrier repair genes, that the TLR3 ligand Poly (I:C) also induced expression and function of tight junctions, and that the ncRNA U1 acts in a TLR3-dependent manner to induce expression of skin barrier repair genes. These observations were shown to have functional relevance as Tlr3-/- mice displayed a delay in skin barrier repair following UVB damage. Combined, these data further validate the conclusion that recognition of endogenous RNA by TLR3 is an important step in the program of skin barrier repair.

Show MeSH
Related in: MedlinePlus