title: Prevention of UVB-induced immunosuppression in mice by the green tea polyphenol (-)-epigallocatechin-3-gallate may be associated with alterations in IL-10 and IL-12 production.
abstract: UV exposure of the skin, particularly UVB (290-320 nm), causes adverse biological effects, including alterations in cutaneous immune cells, photoaging and photocarcinogenesis. Several studies have shown that polyphenolic compounds isolated from green tea afford protection against UVB-induced inflammatory responses and photocarcinogenesis in murine models. In this study we show that topical application of (-)-epigallocatechin-3-gallate (EGCG) (3 mg/mouse), a major polyphenolic component of green tea, before a single low dose UVB exposure (72 mJ/cm(2)) to C3H/HeN mice prevented UVB-induced inhibition of the contact hypersensitivity response and tolerance induction to the contact sensitizer 2, 4-dinitrofluorobenzene. Topical application of EGCG before UVB exposure reduced the number of CD11b+ monocytes/macrophages and neutrophils infiltrating into skin inflammatory lesions, which are considered to be responsible for creating the UV-induced immunosuppressive state. In addition, application of EGCG before UVB exposure decreased UVB-induced production of the immunomodulatory cytokine interleukin (IL)-10 in skin as well as in draining lymph nodes (DLN), whereas production of IL-12, which is considered to be a mediator and adjuvant for induction of contact sensitivity, was found to be markedly increased in DLN when compared with UVB alone-exposed mice. Taken together, our data demonstrate that EGCG protects against UVB-induced immunosuppression and tolerance induction by: (i) blocking UVB-induced infiltration of CD11b+ cells into the skin; (ii) reducing IL-10 production in skin as well as in DLN; (iii) markedly increasing IL-12 production in DLN. Protection against UVB-induced immunosuppression by EGCG may be associated with protection against UVB-induced photocarcinogenesis.
authors.affiliation: Department of Dermatology, Case Western Reserve University, 11100 Euclid Avenue, Cleveland and University Hospitals of Cleveland and VA Hospital, Cleveland, OH 44106, USA. sxk32@po.cwru.edu
authors.forename: S K
authors.initials: SK
authors.lastname: Katiyar
authors.forename: A
authors.initials: A
authors.lastname: Challa
authors.forename: T S
authors.initials: TS
authors.lastname: McCormick
authors.forename: K D
authors.initials: KD
authors.lastname: Cooper
authors.forename: H
authors.initials: H
authors.lastname: Mukhtar
mesh_terms: D000287:Administration, Topical; D000818:Animals; D016588:Anticarcinogenic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D007107:Immune System / Q000187:drug effects* / Q000528:radiation effects; D016753:Interleukin-10 / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000096:biosynthesis*; D051379:Mice; D008809:Mice, Inbred C3H; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D016588:Anticarcinogenic Agents; D013662:Tea; D016753:Interleukin-10; D018664:Interleukin-12; D002392:Catechin; C045651:epigallocatechin gallate