Metallothionein I and II gene knock-out mice exhibit reduced tolerance to 24-h sodium lauryl sulphate patch testing.

BACKGROUND

Metallothioneins (MTs) are a group of proteins widely distributed in tissues regulating metal metabolism, scavenging free radicals, and taking part in immunological reactions. Knockout mice for MT genes I and II (MT(-/-)) exhibit reduced tolerance to ultraviolet B injury in vivo. Upregulation of MT proteins can be found at positive allergy patch-test sites; however, the role of MTs in skin irritation has not been investigated.

AIM: To evaluate the role of MT genes in sodium lauryl sulphate (SLS)-induced skin irritation. SLS is a well-known model irritant in the study of experimental irritant contact dermatitis.

METHODS

Skin irritation was induced in mice by applying closed-patch testing of 2.5%, 5%, 7.5% and 10% SLS in distilled water on the right dorsal skin of MT(-/-) mice for 24 h. Skin irritation was evaluated visually and by the number of infiltrated inflammatory cells in SLS-irritated skin. Homozygous wild-type mice with intact MT genes (MT(+/+)) tested at the same time served as controls.

RESULTS

MT(-/-) mice showed a much higher degree of skin inflammation than did MT(+/+) mice. Numbers of infiltrated inflammatory cells were 312.8 +/- 50.9 vs. 136.2 +/- 13.1 for 2.5%, 430.2 +/- 49.3 vs. 242.6 +/- 28.6 for 5%, 540.2 +/- 28.4 vs. 437.6 +/- 22.2 for 7.5%, and 690.6 +/- 31.0 vs. 559.0 +/- 37.8 for 10% SLS in MT(-/-) and MT(+/+) mice, respectively (P < 0.05, Mann-Whitney U test).

CONCLUSIONS

These results clearly suggest that the MTI and MTII genes may play an important protective role in SLS irritation. It would be valuable to study whether topical MTs can prevent or treat skin irritation.