title: [Inhibition of elicitation of allergic contact dermatitis by topical use of Z-VAD-FMK, a broad caspase inhibitor: experiment in mice].
abstract: OBJECTIVE
  To explore the effects of N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), a broad caspase inhibitor, on the elicitation of murine allergic contact dermatitis (ACD) and examine the effects on T lymphocytes.
  
  
  METHODS
  1-fluoro-2,4-dinitrobenzene (DNFB) was used to establish the classical murine model of ACD. Different concentrations of Z-VAD-FMK were applied before ear provocation. Several parameters were detected, including ear swelling degree, weight differences and thickness of ear tissue under microscope between 2 ears. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of Th1 cytokines (INF-γ and IL-2) in ear tissues. Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to detect their levels of mRNA and the results were shown as "copies relative to one million housekeeping genes". Local lymph node assay (LLNA) was conducted. Bromodeoxyuridine-flow cytometry was used to detect the proliferation of T lymphocytes in local lymph node and flow cytometry to detect the activation of T lymphocytes.
  
  
  RESULTS
  The right ear swelling degree, weight differences and thickness between two ears in the 1.25 mmol/L Z-VAD-FMK group were (12.6 ± 1.2)×10(-2) mm, (3.1 ± 0.2) mg, and (12.1 ± 1.1)×10(-2) mm respectively. And they were all significantly lower than those of the negative control group((17.4 ± 1.6)×10(-2) mm, (4.2 ± 0.3) mg, (16.7 ± 1.5)×10(-2) mm;q = 3.25, 2.98, 3.12, all P < 0.05). The levels of INF-γ and IL-2 in the ear skin lesions of 1.25 mmol/L Z-VAD-FMK group were (856 ± 45) and (167 ± 12) pg/ml respectively and they were both significantly lower than those of the negative control group ((1180 ± 58) and (225 ± 16) pg/ml; q = 3.11, 3.14, both P < 0.05). The mRNA levels of the above two cytokines were 152 ± 12 and 96 ± 8 respectively and they were both significantly lower than those of the negative control group (220 ± 15 and 156 ± 11;q = 3.15, 3.42, both P < 0.05). In LLNA, the mean intensity of BrdU in T lymphocytes of 1.25 mmol/L Z-VAD-FMK-treated group was significantly weaker than that of the negative control group (185 ± 15 vs 298 ± 21, q = 3.02, P < 0.05). The percent of activation markers-positive T lymphocytes of the Z-VAD-FMK group were 7.8% ± 0.7%, 9.8% ± 0.8% and 31.2% ± 2.8% respectively and they were all significantly lower than those of the negative control group (10.5% ± 1.0%, 14.5% ± 1.1%, 46.5% ± 3.2%, q = 3.16, 3.52, 3.11, all P < 0.05).
  
  
  CONCLUSIONS
  Topical use of Z-VAD-FMK prior to ear provocation can suppress the proliferation and activation of T lymphocytes in both skin tissues and local lymph nodes and thus result in the inhibitory effect of allergic contact dermatitis.
authors.affiliation: Department of Dermatology, Shandong University, Jinan, China.
authors.forename: Yuan-yuan
authors.initials: YY
authors.lastname: Li
authors.forename: Chun-lin
authors.initials: CL
authors.lastname: Yan
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D061945:Caspase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D017449:Dermatitis, Allergic Contact / Q000276:immunology / Q000517:prevention & control*; D005260:Female; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone