Limits...
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.

Show MeSH

Related in: MedlinePlus

Photoisomerization of UCA. UV excitation of one isomer leads to the formation of the other isomer (A). The concentrations of UCA isomers is measured in the cell culture medium of HCE-2 cells (B) and HCECs (C) treated with 100 µg/ml cis-UCA for 24 h with or without UV irradiation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2742640&req=5

f4: Photoisomerization of UCA. UV excitation of one isomer leads to the formation of the other isomer (A). The concentrations of UCA isomers is measured in the cell culture medium of HCE-2 cells (B) and HCECs (C) treated with 100 µg/ml cis-UCA for 24 h with or without UV irradiation.

Mentions: In the functional assays with HCE-2 cells and HCECs, cis-UCA was present in the culture medium at the time of irradiation and during the 24 h recovery period. Since the UCA isomers absorb in the UV-B wavelength region and can photoisomerize to each other (Figure 4A), it was investigated whether photoisomerization had actually taken place in the experiments and could have affected the biological response. A total of 16 medium samples from the assays were subjected to HPLC analysis. The mean concentration of cis-UCA in the cis-UCA-treated (100 µg/ml) medium samples was 87.8 µg/ml (HCE-2) and 90.5 µg/ml (HCEC). The rest of the cis-UCA had apparently been taken up by the cells. Trans-UCA was detected in the non-irradiated samples at levels of 6.4% in HCE-2 cells and 4.0% in HCECs from the total UCA (Figure 4B,C). After exposure to UV-B irradiation as shown above, the net photoisomerization to trans-UCA was 13.1% in HCE-2 cells and 11.1% in HCECs. The cis-UCA concentrations were 72.3 μg/ml in HCE-2 cells and 74.9 μg/ml in HCECs in response to UV-B (Figure 4). This level of photoisomerization was estimated to have a negligible effect on cytokine secretion and viability.


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)

Photoisomerization of UCA. UV excitation of one isomer leads to the formation of the other isomer (A). The concentrations of UCA isomers is measured in the cell culture medium of HCE-2 cells (B) and HCECs (C) treated with 100 µg/ml cis-UCA for 24 h with or without UV irradiation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Photoisomerization of UCA. UV excitation of one isomer leads to the formation of the other isomer (A). The concentrations of UCA isomers is measured in the cell culture medium of HCE-2 cells (B) and HCECs (C) treated with 100 µg/ml cis-UCA for 24 h with or without UV irradiation.
Mentions: In the functional assays with HCE-2 cells and HCECs, cis-UCA was present in the culture medium at the time of irradiation and during the 24 h recovery period. Since the UCA isomers absorb in the UV-B wavelength region and can photoisomerize to each other (Figure 4A), it was investigated whether photoisomerization had actually taken place in the experiments and could have affected the biological response. A total of 16 medium samples from the assays were subjected to HPLC analysis. The mean concentration of cis-UCA in the cis-UCA-treated (100 µg/ml) medium samples was 87.8 µg/ml (HCE-2) and 90.5 µg/ml (HCEC). The rest of the cis-UCA had apparently been taken up by the cells. Trans-UCA was detected in the non-irradiated samples at levels of 6.4% in HCE-2 cells and 4.0% in HCECs from the total UCA (Figure 4B,C). After exposure to UV-B irradiation as shown above, the net photoisomerization to trans-UCA was 13.1% in HCE-2 cells and 11.1% in HCECs. The cis-UCA concentrations were 72.3 μg/ml in HCE-2 cells and 74.9 μg/ml in HCECs in response to UV-B (Figure 4). This level of photoisomerization was estimated to have a negligible effect on cytokine secretion and viability.

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