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Cis-urocanic acid suppresses UV-B-induced interleukin-6 and -8 secretion and cytotoxicity in human corneal and conjunctival epithelial cells in vitro.

Viiri J, Jauhonen HM, Kauppinen A, Ryhänen T, Paimela T, Hyttinen J, Sorri I, Laihia JK, Leino L, Kaarniranta K - Mol. Vis. (2009)

Bottom Line: Moreover, UV-B increased caspase-3 activity in both cell types as analyzed with ELISA.No significant effects on IL-6 or IL-8 secretion, caspase-3 activity, or viability of the non-irradiated cells were observed with 100 microg/ml cis-UCA in both cell types.The 5,000 microg/ml concentration was toxic.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Institute of Clinical Medicine, University of Kuopio, Kuopio, Finland.

ABSTRACT

Purpose: Urocanic acid (UCA) is a major ultraviolet (UV)-absorbing endogenous chromophore in the epidermis and is also an efficacious immunosuppressant. The anti-inflammatory and cytoprotective effects of cis-UCA were studied in ocular surface cell cultures exposed to UV-B irradiation.

Methods: Human corneal epithelial cells (HCE-2) and human conjunctival epithelial cells (HCECs) were incubated with 10, 100, 1,000, and 5,000 microg/ml cis-UCA with and without a single UV-B irradiation dose. The concentrations of IL-1beta, IL-6, IL-8, and TNF-alpha in the culture medium and caspase-3 activity in the cell extract sampled were measured by enzyme-linked immunosorbent assay (ELISA). Cell viability was measured by the colorimetric MTT (3-(4,5-dimethyldiazol- 2-yl)-2,5-diphenyltetrazolium bromide) assay.

Results: UV-B irradiation multiplied interleukin IL-6 and IL-8 secretion levels in HCE-2 cells and HCECs as analyzed with ELISA. Cell viability as measured by the MTT assay declined by 30%-50% in HCE-2 cells and by 20%-40% in HCECs after UV-B irradiation. Moreover, UV-B increased caspase-3 activity in both cell types as analyzed with ELISA. Treatment with 100 microg/ml cis-UCA completely suppressed IL-6 and IL-8 secretion, decreased caspase-3 activity, and improved cell viability against UV-B irradiation. No significant effects on IL-6 or IL-8 secretion, caspase-3 activity, or viability of the non-irradiated cells were observed with 100 microg/ml cis-UCA in both cell types. The 5,000 microg/ml concentration was toxic.

Conclusions: These findings indicate that cis-UCA may represent a promising anti-inflammatory and cytoprotective treatment option to suppress UV-B-induced inflammation and cellular damage in human corneal and conjunctival epithelial cells.

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Related in: MedlinePlus

Effect of cis-UCA on UV-irradiation-induced IL-6 secretion. The HCE-2 cells (A) and HCECs (B) were non-irradiated (C) or UV-irradiated (UV; lower panels), or exposed to different concentrations of cis-UCA or UV irradiated and treated with cis-UCA for 24, 48, or 72 h (upper panels). For statistical analysis, cis-UCA+UV samples were compared with UV samples. An asterisk indicates p<0.05, and a double asterisk denotes p<0.001 (n=6 dishes).
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f2: Effect of cis-UCA on UV-irradiation-induced IL-6 secretion. The HCE-2 cells (A) and HCECs (B) were non-irradiated (C) or UV-irradiated (UV; lower panels), or exposed to different concentrations of cis-UCA or UV irradiated and treated with cis-UCA for 24, 48, or 72 h (upper panels). For statistical analysis, cis-UCA+UV samples were compared with UV samples. An asterisk indicates p<0.05, and a double asterisk denotes p<0.001 (n=6 dishes).

Mentions: In non-irradiated cells, the 10 and 100 µg/ml concentrations of cis-UCA had only a negligible effect on IL-6 production while treatment with 1,000 µg/ml of cis-UCA evoked a mild but significant elevation on IL-6 levels in both cell types. A major decrease in IL-6 secretion was observed with 5,000 µg/ml cis-UCA in all time points (Figure 1A,B). Exposure of the HCE-2 cells and HCECs to UV-B irradiation induced a maximum sevenfold to ninefold increase and twofold increase in the measured IL-6 concentrations, respectively. Treatment of both cell lines with cis-UCA at all studied concentrations significantly decreased the UV-B-induced IL-6 secretion (Figure 2A,B). The 100 µg/ml concentration of cis-UCA completely restored the UV-B-induced increase in IL-6 secretion back to the level detected in the non-irradiated cells after the 24-, 48-, and 72-h follow-up. IL-1β could not be detected in the control, cis-UCA-treated, or UV-B-irradiated cells (data not shown).


Cis-urocanic acid suppresses UV-B-induced interleukin-6 and -8 secretion and cytotoxicity in human corneal and conjunctival epithelial cells in vitro.

Viiri J, Jauhonen HM, Kauppinen A, Ryhänen T, Paimela T, Hyttinen J, Sorri I, Laihia JK, Leino L, Kaarniranta K - Mol. Vis. (2009)

Effect of cis-UCA on UV-irradiation-induced IL-6 secretion. The HCE-2 cells (A) and HCECs (B) were non-irradiated (C) or UV-irradiated (UV; lower panels), or exposed to different concentrations of cis-UCA or UV irradiated and treated with cis-UCA for 24, 48, or 72 h (upper panels). For statistical analysis, cis-UCA+UV samples were compared with UV samples. An asterisk indicates p<0.05, and a double asterisk denotes p<0.001 (n=6 dishes).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2742640&req=5

f2: Effect of cis-UCA on UV-irradiation-induced IL-6 secretion. The HCE-2 cells (A) and HCECs (B) were non-irradiated (C) or UV-irradiated (UV; lower panels), or exposed to different concentrations of cis-UCA or UV irradiated and treated with cis-UCA for 24, 48, or 72 h (upper panels). For statistical analysis, cis-UCA+UV samples were compared with UV samples. An asterisk indicates p<0.05, and a double asterisk denotes p<0.001 (n=6 dishes).
Mentions: In non-irradiated cells, the 10 and 100 µg/ml concentrations of cis-UCA had only a negligible effect on IL-6 production while treatment with 1,000 µg/ml of cis-UCA evoked a mild but significant elevation on IL-6 levels in both cell types. A major decrease in IL-6 secretion was observed with 5,000 µg/ml cis-UCA in all time points (Figure 1A,B). Exposure of the HCE-2 cells and HCECs to UV-B irradiation induced a maximum sevenfold to ninefold increase and twofold increase in the measured IL-6 concentrations, respectively. Treatment of both cell lines with cis-UCA at all studied concentrations significantly decreased the UV-B-induced IL-6 secretion (Figure 2A,B). The 100 µg/ml concentration of cis-UCA completely restored the UV-B-induced increase in IL-6 secretion back to the level detected in the non-irradiated cells after the 24-, 48-, and 72-h follow-up. IL-1β could not be detected in the control, cis-UCA-treated, or UV-B-irradiated cells (data not shown).

Bottom Line: Moreover, UV-B increased caspase-3 activity in both cell types as analyzed with ELISA.No significant effects on IL-6 or IL-8 secretion, caspase-3 activity, or viability of the non-irradiated cells were observed with 100 microg/ml cis-UCA in both cell types.The 5,000 microg/ml concentration was toxic.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Institute of Clinical Medicine, University of Kuopio, Kuopio, Finland.

ABSTRACT

Purpose: Urocanic acid (UCA) is a major ultraviolet (UV)-absorbing endogenous chromophore in the epidermis and is also an efficacious immunosuppressant. The anti-inflammatory and cytoprotective effects of cis-UCA were studied in ocular surface cell cultures exposed to UV-B irradiation.

Methods: Human corneal epithelial cells (HCE-2) and human conjunctival epithelial cells (HCECs) were incubated with 10, 100, 1,000, and 5,000 microg/ml cis-UCA with and without a single UV-B irradiation dose. The concentrations of IL-1beta, IL-6, IL-8, and TNF-alpha in the culture medium and caspase-3 activity in the cell extract sampled were measured by enzyme-linked immunosorbent assay (ELISA). Cell viability was measured by the colorimetric MTT (3-(4,5-dimethyldiazol- 2-yl)-2,5-diphenyltetrazolium bromide) assay.

Results: UV-B irradiation multiplied interleukin IL-6 and IL-8 secretion levels in HCE-2 cells and HCECs as analyzed with ELISA. Cell viability as measured by the MTT assay declined by 30%-50% in HCE-2 cells and by 20%-40% in HCECs after UV-B irradiation. Moreover, UV-B increased caspase-3 activity in both cell types as analyzed with ELISA. Treatment with 100 microg/ml cis-UCA completely suppressed IL-6 and IL-8 secretion, decreased caspase-3 activity, and improved cell viability against UV-B irradiation. No significant effects on IL-6 or IL-8 secretion, caspase-3 activity, or viability of the non-irradiated cells were observed with 100 microg/ml cis-UCA in both cell types. The 5,000 microg/ml concentration was toxic.

Conclusions: These findings indicate that cis-UCA may represent a promising anti-inflammatory and cytoprotective treatment option to suppress UV-B-induced inflammation and cellular damage in human corneal and conjunctival epithelial cells.

Show MeSH
Related in: MedlinePlus