Evidence that DNA Damage Is a Mediate in Ultraviolet B Radiation-Induced Inhibition of Human Gene Expression: Ultraviolet B Radiation Effects on Intercellular Adhesion Molecule-1 (ICAM-1) Expression

Evidence that DNA Damage Is a Mediate in Ultraviolet B Radiation-Induced Inhibition of Human Gene Expression: Ultraviolet B Radiation E£Fects on Intercellular Adhesion Molecule-1 (ICAM-1) Expression Jean Krutmann, Elisabeth Bohnert,* and Ernst G. Jung* Photodermatology Section, Department of Dermatology, University of Freiburg, Freiburg; and 'Department of Dermatology, Mannheim Medical School, University of Heidelberg, Heidelberg, Germany

Expression of intercellular adhesion molecule-1 (ICAM-1) is a prerequisite for tbe capacity of cells to physically interact with leukocytes. Ultraviolet B radiation previously was found to inhibit interferon y - induced ICAM-1 expression in human keratinocytes by suppressing interferon y-mediated upregulation of ICAM-1 mRNA levels. Because ultraviolet B radiation induces photoproducts in cellular DNA, the potential role of ultraviolet B radiation- induced DNA damage in this system was assessed. For this purpose, cells from a normal donor were compared with cells from patients with xeroderma pigmentosum from complementation groups C and D, Xeroderma pigmentosum cells are defective in the removal of ultraviolet B radiation - induced DNA lesions, and thus lower ultraviolet B radiation doses are required to retain equivalent numbers of DNA photoproducts at a given time point after irradiation. In the present study, ultraviolet B radiation inhibited interferon y-induced ICAM-1 mRNA expression in primary human skin fibroblasts in a manner

R

ecent studies provide clear evidence that the adhesion molecule intercellular adhesion molecule-1 (ICAM1) is of major importance for the capacity of cells to physically interact with leukocytes [1,2], For example, in human keratinocytes, binding of keratinocyte ICAM-1 molecules to leukocyte function-associated antigen-1 (LFA-1) molecules on the surface of T cells provides a co-stimulatory activity necessary for keratinocyte accessory cell function in superantigen-induced T-cell activation [3], In addition, keratinocyte ICAM-1 expression plays a pivotal role in the generation and maintenance of an intraepidermal infiltrate by forming the molecular matrix, to which LFA-1 -expressing leukocytes bind in inflammatory skin diseases [4,5], Expression of ICAM-1 molecules in keratinocytes is regulated by selected cytokines and by ultraviolet B radiation (UVBR) [2,6,7], Specifically, low constitutive ICAM-1 expression is markedly enhanced upon in vitro stimulation of keratiManuscript received September 27, 1993; accepted for publication December 20, 1993, Reprint requests to: Dr, Jean Krutmann, Pbotodermatology Section, Department of Dermatology, University of Freiburg, Hauptstrasse 7, D-79104 Freiburg i, Br,, Germany, Abbreviations: ICAM-1, intercellular adhesion molecular-l;-fcFA-1, leukocyte function associated antigen-1; rh IFN, recombinant human interferon; XP, xeroderma pigmentosum.

0022-202X/94/S07,00

identical to that previously observed for keratinocytes. Comparative studies employing normal versus xeroderma pigmentosum fibroblasts revealed that in xeroderma pigmentosum fibroblasts, two- to threefold lower ultraviolet B radiation doses were required to achieve inhibition equivalent to that observed in normal fibroblasts. In irradiated normal cells, inhibition of interferon y-induced ICAM-1 mRNA expression was transient and restored 12 h after ultraviolet B radiation exposure. In contrast, in xeroderma pigmentosum complementation group D cells, no restoration could be observed for up to 48 h, but responsiveness was restored in xeroderma pigmentosum complementation group C cells after 24 h. These studies indicate that ultraviolet B radiation-induced inhibition of interferon y-mediated ICAM-1 expression involves the generation of DNA photoproducts. Key words: keratinocytes/photoimmunology/adhesion molecules/pyrimidine dimers. J Invest Dermatol 102:428-432, 1994

nocytes with recombinant human interferon (rh IFN) y, and this upregulation is efficiently blocked, if keratinocytes are exposed to sublethal doses of UVBR prior to IFNy stimulation [8,9], When this inhibitory effect of UVBR was further characterized, it became evident that UVBR inhibited ICAM-1 expression at a pretranslational level by suppressing IFNy-induced upregulation of ICAM-1 mRNA steady-state levels [10], UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA expression is transient. This conclusion is based on the observation that IFNr-induced ICAM-1 mRNA expression is inhibited by UVBR, if irradiated cells are IFNy-stimulated immediately after UVBR exposure, whereas IFN7 is able to increase ICAM-1 mRNA levels, if irradiated cells are incubated for 12 h prior to cytokine stimulation [10], At a molecular level, UVBR is known to induce specific damage to cellular DNA, which is repaired by keratinocytes within hours via the nucleotide excision repair pathway [11], The importance of DNA damage and repair for lethality, mutation, and neoplastic transformation is well recognized [12], There is, however, increasing evidence that DNA damage may also play a role in the regulation of gene expression in human cells [13], The present study addressed the question whether DNA damage is involved in UVBR-induced regulation of the expression of the human ICAM-1 gene. For this purpose, a comparison of UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA expression and the restoration of IFNy responsiveness in UVB-irradiated, normal, and DNA exci-

Copyright © 1994 by The Society for Investigative Dermatology, Inc,

428

VOL, 102, NO, 4 APRIL, 1994

sion repair defective fibroblasts was undertaken. If lower UVBR doses are sufficient to retain an equivalent number of DNA lesions at a given time point post-exposure in DNA repair deficient cells, as compared to normal cells, then UVBR dose-response curves as well as t b e capacity to restore IFNy responsiveness following UVBR exposure between DNA repair deficient and normal cells should diflfer correspondingly [13],

DNA DAMAGE AND ICAM-1 REGULATION

1 2 3 4 5 6 7 8 9

429

10 11 12

3.3 KB

MATERIALS AND METHODS C e l l Culture Primary human skin fibroblasts were grown from biopsies obtained, after informed consent, from tbe non-UVBR-exposed buttock skin ofa normal, healthy individual (cell line N46) with skin type 3 and no personal history of skin cancer or from non-lesional skin of two patients with xeroderma pigmentosum (XP), The XP strains were assigned to XP complementation group D (XP825D) and C (XPl 12C), using the heterodikary o n complementation test as previously described [14], and exhibited residual unscheduled DNA synthesis levels of approximately 15% (XPD) and 1 2 % (XPC), respectively. All fibroblast strains were grown in Eagle's modified essential medium (Gibco Laboratories, Berlin, Germany) supplemented w i t h 10% fetal bovine serum (Gibco Laboratories, Berlin, Germany), Cells w e r e grown in 140 X 20 mm culture dishes until subconfluency in a humidified atmosphere containing 5% CO2 at 37 °C, Ultraviolet B Radiation For UVB irradiation, medium was replaced by phosphate-buffered saline and cells were exposed as previously described to U V radiation (0-100 J/m^) using a bank of 4 FS20 sunlamp bulbs (Westinghouse Electric Corp,, Pittsburgh, PA), which are known to emit primarily i n the UVB range (280-320 nm) [9,10,15], The UVB output was monitored by means of an IL1700 research radiometer and SEE240 UVB photodetector (International Light, Newburyport, MA) and was approximately 24 X 10"^ W/cm^ at a tube to target distance of 22 cm. After irradiation, cells were washed and cultured in medium in the presence or absence of 500 U / m l of rh IFNy (Genzyme Inc, Boston, MA), Assessment o f Cell Viability Viability of UVB-irradiated fibroblasts was determined over a 48-h incubation period as their capacity to exclude 0,2% trypan blue. The cells were counted using a hemocytometer and the percentage of non-viable cells was calculated from the number of stained cells over a total of 200 cells. In addition, cell viability was determined by assessing the capacity of fibroblasts to incorporate ['H]-thymidine 24 and 48 h after UVBR exposure. For this purpose, irradiated or unirradiated fibroblasts were cultured for 24 or 48 h in 96-well flat bottom microtiter plates (Gibco, Berlin, Germany) at a density of 2 X lO'' cells/well. Cultures were pulsed with ['H]-thymidine (1 /iCi/well) for the last 8 h of incubation, and the incorporation of ['H]thymidine into DNA was assessed as previously described [15], Briefly, following media aspiration, cultures were trypsinized, and harvested onto nitrocellulose filter paper using a Skatron cell harvester. Incorporated [^H]thymidine was determined by liquid scintillation spectroscopy. All cultures were carried out in triplicate, and results were calculated as the mean cpm ± SD, Northern Blot Analysis Northern blot analysis of ICAM-1 mRNA was performed as previously described [16], Briefly, cultured cells were gently detached and subsequently lysed in low-salt tris-bufFer containing 1,2% Nonidet P-40/5% Sucrose, Total RNA was isolated by extraction with an acid guanidinium thiocyanate phenol chloroform mixture [16], The concentration of RNA was determined from absorption at (A)260 nm, and A260/A280 ratios were greater than 1,7, RNA (10/ig) was subjected to electrophoresis in 1,2% agarose gels containing formaldehyde (2,2 M) followed by transfer to nylon membranes (Hybond N; Amersham-Buchler, Braunschweig, Germany), Equivalent loading and uniform transfer of RNA were assured by etbidium bromide staining of tbe gels before and after Northern transfer. Membranes were prehybridized (4 h) and hybridized (overnight) at 42°C witb 6 X SSPE:5 X Denhardt's solution:200/ig/ml salmon sperm DNA, ICAM-1 specific mRNA was detected using a 1,3-kb cDNA probe [17], kindly provided by Dr, T, A, Springer, Dana Farber Cancer Institute, Boston, MA, Control hybridizations used a cDNA probe encoding the house-keeping gene GAPDH, The cDNA fragments were biotin-14-dATP-labeled by nick translation using the BioNick labeling system (Gibco/Bethesda Research Laboratories, Berlin, Germany), Northern blot analysis was performed under stringent washing conditions (twice for 5 min using 2 X SSC/0,5% sodium dodecylsulfate (SDS) at 60°C and once for 40 min using 0,1% SSC/1% SDS at 50°C), Signals were detected using the Photogene detection system (Gibco/Bethesda Research Laboratories, Berlin, Germany), Autoradiography was carried out for 15 min at 25°C using Kodak XAR films. The relative fold increase and decrease of ICAM-1 mRNA expression was normalized to the GAPDH mRNA control and

GAPDH

Figure 1. Effect of UVBR on IFNy-induced ICAM-1 mRNA expression in normal versus DNA repair deficient primary human skin fibroblasts, Fibroblasts were obtained from a healthy donor (lanes I, 3, 5, 7, 9, II) or from a patient with XP complementation group D (lanes 2, 4, 6, 8, 10, 12). Cells were incubated without stimulus (lanes 1, 2), or stimulated with 500 U/ml of rh IFNy (lanes 3-12). In lanes 5-12, cells were exposed to decreasing doses of UVBR, IFN7 was added immediately after UVBR exposure {lanes 5 and 6, 100 J/m^; lanes 7 and 8, 50 J/m^; lanes 9 and 10, 25 J/m^; lanes 11 and 12, 12,5 J/m^ UVBR), Cells were harvested after a 4-h incubation period. Northern blot analysis of total RNA {10 fig) used a biotin-labeled cDNA probe encoding for ICAM-1, A GAPDH probe served as a control. Data represent one of two essentially identical experiments.

assessed using a laser densitometer (Pharmacia LKB, Freiburg, Germany), kindly provided by Dr, P, Nielsen, Max-Planck Institut fur Immunbiologie (Freiburg, Germany), RESULTS In previous experiments it has been demonstrated that in vitro irradiation of cultured human keratinocytes with sublethal doses of UVBR (0-lOOJ/m^) prior to cytokine stimulation inhibited IFNy-induced ICAM-1 mRNA expression [8,9], In the present study, primary human skin fibroblasts rather than primary human keratinocytes were employed. Exposure of fibroblasts from a normal donor to increasing doses of UVBR (O-lOOJ/m^) inhibited IFNy-induced ICAM-1 mRNA expression in a dose-dependent manner (Fig 1), Significant inhibition could be observed upon exposure of these cells to 50 to 100 J/m^ UVBR (Figs 1 and 3), Exposure to 100 J/m^ UVBR was sufficient to reduce ICAM-1 mRNA steady-state levels in IFNy-stimulated fibroblasts to background levels (Fig 1), To determine the potential role of DNA photoproducts in UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA expression, in the following experiments, UVBR effects on ICAM-1 mRNA expression in primary human skin fibroblasts from a healthy, normal individual were compared to primary human skin fibroblasts from XP patients of complementation groups D and C, No constitutive inhibition of XPD or XPC fibroblasts to the IFN7induced upregulation of ICAM-1 mRNA could be observed (Figs 1 and 3), The UVB doses employed in these experiments did not significantly decrease the capacity of any of the fibroblast strains used to exclude trypan blue, that is, the percentage of non-viable cells ranged from 3 - 8 % 24 h and from 5 - 9 % 48 h after UVBR exposure. In addition, normal or XP fibroblasts did not differ with regards to their capacity to incorporate [^H]-thymidine 24 and 48 h after UVBR exposure (Fig 2), Moreover, transcriptional activity of the house keeping gene GAPDH was essentially identical for XP fibroblasts as compared to normal fibroblasts under any of the conditions tested (Figs 1 and 3), Exposure to 25 J/m^ UVBR almost completely inhibited IFNyinduced ICAM-1 mRNA expression in XPD cells, whereas in normal cells no significant inhibition could be observed (Fig 1), Expo-

430

KRUTMANN ET AL

THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

CO

3

a

y

e

12,5

10000

25,0

37,5

50,0

62,5

75,0

87,5

100,0

I

9000

aooo 7000

eooo

B

6000 4000 3000 2000 1000 0

25

50

100

Figure 3. Semi-quantitative assessment of UVBR-induced inhibition of ICAM-1 mRNA expression in IFNy-stimulated fibroblasts, Fibroblasts from a normal individual (O), a patient with XP complementation group D (D), or a patient with XP complementation group C (V) were exposed to increasing doses of UVBR (0-100 J/m^), and were then stimulated with 500 U/ml of rh IFNy for 4 h immediately after UVBR exposure, ICAM-1 mRNA expression was assessed by Northern blot analysis as previously described. Following hybridization with ICAM-1 and GAPDH specific, biotin-labeled probes, blots were scanned by laser densitometry and normalized for GAPDH transcripts, IFNy-induced ICAM-1 mRNA expression was set as 100%, Data represent duplicates ± SD of one of two essentially identical experiments.

J/m

UVB-irradiated XPDfibroblastswere not capable of upregulating Figure 2. [H^]-thymidine incorporation into normal and DNA repair deficient primary human skin fibroblasts, Fibroblasts from a healthy, normal ICAM-1 mRNA expression upon IFNy stimulation even after a 24donor (hatched bars), a patient with XP complementation group D (solid to 48-h incubation period (Fig 4a, shown for 24 h), but IFNybars), or a patient with XP complementation group C (crosshatched bars) were induced ICAM-1 mRNA expression was found to be restored 24 h exposed to increasing doses (0-100 J/m^) of UVBR (x axis), and subseafter irradiation in XPC cells (Fig 4b). quently incubated for 24 (A) or 48 (B) h. After an 8-h pulse with ['Hjthymidine, the cultures were processed for determination of incorporation DISCUSSION of [^H]-thymidine, as described in Materials and Methods. Data represent one In previous studies human keratinocytes were used to study the of three essentially identical experiments and are given as the mean values of effects of UVBR on ICAM-1 mRNA expression [7-10], Although triplicate cultures ± SD (y axis). Background radioactivity was always less than 500 cpm. we are aware of the fact that keratinocytes are the most relevant sure of XPD cells to 50 J/m^ UVBR decreased IFNy-indoced ICAM-1 mRNA expression to background levels, whereas in IFNy-stimulated normal cells, the identical UVBR dose only partially inhibited ICAM-1 mRNA expression, Semiquantitative assessment of ICAM-1 mRNA expression in UVB-irradiated cells revealed that two- to threefold smaller doses of UVBR were sufficient in XPD cells to achieve inhibition of IFNy-mediated ICAM-1 mRNA expression to an extent identical to that observed in normal cells (Fig 3), Essentially identical UVBR dose-response differences could be observed, when cells from a different XP patient (XPC) were compared to normal cells (Fig 3). Ultraviolet B radiation - induced inhibition of IFNy-mediated ICAM-1 mRNA expression in human keratinocytes was shown to be transient and found to be restored 12 h post exposure [10], To examine whether primary human skinfibroblastswere also able to restore IFNy responsiveness following UVBR exposure, in the following experiments normalfibroblastswere exposed to-100 J/m^ UVBR and subsequently stimulated with IFNy either immediately after UVBR exposure, or after a 12 or 24 h restoration period, IFNy-induced ICAM-1 mRNA expression was inhibited, if UVBirradiated normal cells were IFNy-stimulated immediately after UVBR exposure, but induction of ICAM-1 mRNA expression could be observed in tbese cells, if IFNy was added after a 12-h incubation period (Fig 4a), In marked contrast, no restoration of IFNy-responsiveness could be observed in UVB-irradiated XPD and XPC cells after a 12-h restoration period (Fig 4a,b). In addition.

cellular target for UVBR, in the present study, primary human skin fibroblasts were used. The decision to use fibroblasts rather than keratinocytes was based on ethical considerations, which did not allow us to obtain sufficient numbers of primary keratinocytes from patients with xeroderma pigmentosum. In addition, the present study provides clear evidence that keratinocytes andfibroblastsbehave essentially identical with regards to UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA expression. Thus, the UVBR doses necessary for inhibition of IFNy-mediated ICAM-1 mRNA expression in fibroblasts proved identical to those previously defined for primary keratinocytes, and in both inhibition of IFNy responsiveness was transient and restoration could be observed 12 h after UVBR exposure. These results indicate that UVBR-induced inhibition of IFNy-stimulated ICAM-1 mRNA expression is not specific for cultured human keratinocytes, and that an essentially identical inhibitory effect may be observed, if IFNy-induced ICAM-1 mRNA expression is assessed in UVB-irradiated, primary human skin fibroblasts. It is therefore conceivable to assume that primary human skin fibroblasts represent a suitable model for the study of UVBR effects on the regulation of ICAM-1 mRNA expression in human cells. The present study demonstrates that significantly lower UVBR doses are required to inhibit IFNy-stimulated ICAM-1 mRNA expression in DNA excision repair deficient XP cells, as compared to normal cells. These dose-response differences may not be explained by a change in cell viability, because the UVBR doses employed did not affect the capacity of XP fibroblasts to exclude trypan blue and to incorporate [^H]-thymidine over a 48-h incubation period fol-

DNA DAMAGE AND ICAM-1 REGULATION

VOL, 102, NO, 4 APRIL, 1994

1 2 3 4 5 6 7 8

9 10

3.3 KB

GAPDH

1

2

3

4

5

6

7

8

9

10

3.3 KB

GAPDH

Figure 4. Restoration of IFN7 responsiveness in UVB-irradiated normal versus DNA repair deficientfibroblasts,Fibroblasts from a normal donor (a, lane 1, b, lane 2) or from a patient with XP complementation group D {a, lane 2) or from a patient with XP complementation group C {b, lane 1) were left unstimulated. For IFNy stimulation, fibroblasts from a normal donor (a, lanes 3, 5, 7, 9, b, lanes 4, 6, 8, 10) or from a patient with XP complementation group D (a, lanes 4, 6, 8, 10) or a patient with XP complementation group C {b, lanes 3, 5, 1, 9) were stimulated with 500 U/ml of rh IFNy, In lanes 1-4, cells were incubated for 4 \i {lanes 1 and 2, unstimulated cells;/anes 3 and 4, IFNy-stimulated cells). In lanes 5-10, cells were exposed to 100 J/m^ UVBR, and then IFNy-stimulated for 4 h immediately after UVBR exposure {lanes 5 and 6), a 12-h incubation period {lanes 7 and 8), or a 24-h incubation period {lanes 9 and 10). ICAM-1 mRNA expression was determined as previously described. Data represent two independent experi-

lowing UVBR exposure, as compared to normal fibroblasts. The observed differences between normal cells and XP cells were not specific for a particular patient, because essentially identical results were obtained, if cells from two different XP patients were compared to normal cells. Moreover, in XP cells, UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA upregulation was not restored after a 12-h recovery phase, as was the case for normal cells. Instead, UVBR-induced restoration of IFNy responsiveness required a 24-h incubation period in XPC cells, whereas in XPD cells restoration of IFNy responsiveness was not observed up to 48 h after UVB exposure, XPfibroblastsand normalfibroblastsdid not differ with regards to their capacity to incorporate ['H]-thymidine as well as to transcriptional activity of the house keeping gene GAPDH, Thus, the delayed recovery of XPfibroblastsfrom UVB irradiation was not due to the possibility that the XPfibroblastsemployed in the present study, as compared to normal fibroblasts, might bave lower metabolic activities in general. Taken together, these studies

431

provide strong evidence that DNA damage is a mediate in UVBRinduced inhibition of IFNy-stimulated ICAM-1 mRNA expression in human cells. Restoration of IFNy responsiveness in normal human cells may thus reflect their capacity to remove DNA photoproducts via the nucleotide excision repair pathway, UVBR-induced DNA damage previously has been shown to be involved in gene regulation of human cells [13], Exposure of human cells to cytotoxic doses of UVC (< 280 nm) radiation induced the expression of the human collagenase, metallothionein, and c-fos genes [18]. The induction of these genes by UVCR involved DNA damage, which lead to the activation of nuclear transcription factors and subsequent upregulation of the corresponding mRNA levels [18], Transcription factors do not only increase, but may also suppress the transcriptional activation of selected genes [19], Preliminary evidence has been reported indicating the existence of a DNA binding protein, which seems to be capable of inhibiting the IFNymediated transcriptional activation of the human ICAM-1 gene.t It is therefore tempting to speculate that UVBR-induced DNA damage may directly or indirectly affect the activation of a similar or even identical factor, which is capable of suppressing IFNy-induced ICAM-1 transcription in UVB-irradiated cells. Exposure of cells to UVBR is known to induce a variety of DNA lesions with pyrimidine dimers, 6-4 photoadducts, and Dewar isomers being the major products [11,12]. Although the relevance of a specific DNA photoproduct for UVBR-induced immunomodulation is not known, recent studies in the mouse system indicate that pyrimidine dimer formation may play a role [20]. In this in vivo iTiodel, UVBR-induced immunosuppression is thought to be mediated via keratinocyte-derived, UVBR-induced cytokines including TNFa and IL-10 [21,22], Ultraviolet B radiation - induced immunosuppression could be prevented by the topical treatment of UVB-irradiated mouse skin with liposomes, containing functionally active endonuclease V, an enzyme, which is preferentially involved in the excision repair of pyrimidine dimers [20], The authors therefore speculated that the induction of pyrimidine dimers in UVB-irradiated keratinocytes may represent the initial event responsible for the production of immunosuppressing cytokines [20,23]. Studies to define the precise nature of the DNA lesion involved in UVBR-induced inhibition of IFNy-mediated ICAM-1 mRNA expression are currently underway. In summary, the present study for tbefirsttime provides evidence that DNA damage is a mediate in UVBR-induced suppression of the expression of the immunological key molecule ICAM-1 in human cells. These studies further support the concept of DNA as the major chroinophore in UVBR-induced immunomodulation [20,23]. This work was supported by a grantfrom the Commission of the European Communities program EV5V-CT-91-0034. We would like to acknowledge the superb technical assistance ofFrauke Parlow and to thank Dr. Colin F. Arlett, Brighton, Dr. Susanne Grether-Beck, and Dr. Markus Grewe, Freiburg, for critically reading the manuscript.

REFERENCES 1, Springer TA: Adhesion receptors of the immune system. Nature 346:425-434, 1990 2, Krutmann J: Regulatory interactions between epidermal cell adhesion molecules and cytokines. In: Lugcr TA, Schwarz T (eds,). Epidermal Cytokines and Growth Factors. Marcel Dekker, New York, 1994, pp 415-432 3, NickolofF BJ, Mitra RS, Green J, Zheng XG, Shimizu Y, Thompson C, Turka LA: Accessory function of keratinocytes for superantigens. Dependence on

t Naik S, Li LJ, Nguven T, Shibagaki N, Caughman SW: Identification of the specific region responsible for cycloheximide (CHX)-sensitive repression of ICAM-1 gene transcription {ahstr). f Invest Dermatol 100:554, 1993,

432

4, 5, 6, 7, 8,

9, 10,

11, 12, 13,

KRUTMANN ET AL

THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

lymphocyte function-associated antigen-1/intercellular adhesion moleciile-1 interaction,//mmuno/ 150:2148-2159, 1993 Kupper TS: Mechanisms of cutaneous inflammation. Interaction between epidermal cytokines, adhesion molecules, and leukocytes. Arch Dermatol 125:14061412, 1989 Norris DA: Cytokine modulation of adhesion molecules in tbe regulation of immunologic cytotoxicity to epidermal targets,_/ Invest Dermatol 95:111S120S, 1990 Dustin ML, Singer KH, Tuck DT, Springer TA: Adhesion of T lympboblasts to epidermal keratinocytes is regulated by interferon gamma and is mediated by intercellular adhesion molecule-1 (1CAM-I),yExpMcJ 167:1323-1340,1988 Krutmann J, Trefzer U: Modulation of the expression of intercellular adhesion molecule-1 (ICAM-1) in human keratinocytes by ultraviolet (UV) radiation. Springer Semin Immunopathol 13:333-345, 1992 Norris DA, Lyons MB, Middleton MH, Yohn JJ, Kashihara-Sawami M: Ultraviolet radiation can either suppress or induce expression of intercellular adhesion molecule-1 (ICAM-1) on the surface of cultured human keratinocytes J Invest Dermatol 95:132-138, 1990 Krutmann J, Kock A, Schauer E, Parlow F, Kapp A, Fbrster E, Schopf E, Luger TA: Tumor necrosis factor fi and ultraviolet radiation are potent regulators of human keratinocyte ICAM-1 expression,y7nves(Dermato/95:127 - 1 3 1 , 1990 Krutmann J, Czech W, Parlow F, Trefzer U, Kapp A, Schopf E, Luger TA: Ultraviolet radiation effects on human keratinocyte ICAM-1 expression: UVinduced inhibition of cytokine-induced ICAM-1 mRNA expression is transient, difTerentially restored for IFNy versus TNFa:, and followed by ICAM-1 induction via a TNFa-like pathway,7/ni;es( Dermatol 98:923-928, 1992 Jung EG, Bohnert E: Photobiology of UV-induced DNA damage. In: Krutmann J, Elmets CA (eds,), Photoimmunology—An Update. Blackwell Science Publication Inc, Oxford (in press) Ananthaswamy HN, Pierceall WE: Molecular mechanisms of ultraviolet radiation carcinogenesis. Yearly review, Photochem Photobiol 52:1119-1136, 1990 Karin M, Herrlich P: Cis- and trans-acting genetic elements responsible for induction of specific genes by tumor promotors, serum factors, and stress. In:

14, 15, 16,

17,

18,

19, 20, 21, 22, 23,

Colburn NH (ed,). Genes and Signal Transduction in Multistage Carcinogenesis. Marcel Dekker, New York, 1989, pp 415-440 Thielmann H W , Popanda O, Edler L, Jung EG: Clinical symptoms and D N A repair characteristics of xeroderma pigmentosum patients from Germany CancerRa 51:3456-3470, 1991 Wahl SM, Wahl LM, McCarthy JB: Lymphocyte-mediated activation of fibroblast proliferation and collagen production,//ramimo/ 121:942-947, 1979 Trefzer U, Brockhaus M, Lotscher H, Parlow F, Budnik A, Grewe M,Christoph H, Kapp A, Schopf E, Luger TA, Krutmann J: The 55-kd tumor necrosis factor receptor on human keratinocytes is regulated by tumor necrosis factor a and by ultraviolet B radiation,/ Clin Invest 92:462-470, 1993 Staunton DE, Marlin SD, Stratowa C, Dustin ML, Springer TA: Primary structure of intercellular adhesion molecule-1 (ICAM-1) demonstrates interaction between members of the immunoglobulin and integrin family. Cell 52-925 931, 1988 Stein B, Rahmsdorf HJ, Steffen A, Litfin M, Herrlich P: UV-induced DNA damage is an intermediate step in UV-induced expression of buman immunodeficiency virus type 1, collagenase, c-fos, and metallothionein, Mol Cell Bid 9:5169-5181, 1989 Seto E, Usheva A, Zambetti GP, Momand J, Horikoshi N, Weinmann R, Levine AJ, Shenk T: Wild-type p53 binds to the TATA-binding protein and represses transcription, Proc Natl Acad Sci USA 89:12028 -12032, 1992 Kripke ML, Cox PA, Alas LG, Yarosh DB: Pyrimidine dimers in DNA initiate systemic immunosuppression in UV-irradiated mice, Proc Natl Acad Sci USA 89:7516-7520, 1992 Yoshikawa T, Streilein J W : Genetic basis of the effects of ultraviolet light B on cutaneous immunity. Evidence that polymorphism at the TNFa and Lps loci governs susceptibiltiy, Immunogenetics 32:398-405, 1990 Rivas JM, Ullrich SE: Systemic suppression of delayed-type hypersensitivity by supernatants from UV-irradiated keratinocytes. An essential role for keratinocyte-derived IL-10,y Immuiio/149:3865-3871, 1992 Yarosh DB: The role of DNA damage and UV-induced cytokines in skin cancer, J Photochem Photobiol B: Biol 16:91-94, 1992

ROTHMAN CLUB MEETING REPORT The annual meeting of The Stephen Rothman Club was held at the Faculty Club of George Washington University on Tuesday evening, 7 December 1993, The Rothman Club meets in conjunction with the annual meeting of The American Academy of Dermatology for the purpose of stimulating young people (i.e., residents, fellows, and junior faculty) to consider a career in investigative dermatology. The meeting is named in honor and memory of one of the giants of American investigative dermatology, the late Dr. Stephen Rothman. Eighty-eight individuals attended this year's meeting. Following a reception and meal, Drs, Joy Rico and Kevin Cooper gave presentations concerning formative influences in their academic careers. Following a series of iriformal questions from the audience, an evening of coUegial camaraderie and good cheer was concluded. The Rothman Club is a non-profit organization whose activities are supported predominantly by unrestricted financial donations from industry. The current Counselors of The Rothman Club, Drs. Lee Nesbitt, Jr., Richard Sontheimer, David Woodley, and Kim Yancey, thank the following corporations whose unconditional generosity and support contributed greatly to the success of this year's meeting.

Patrons Janssen Upjohn Westwood-Squibb The Collagen Corporation Roche Dermatologies

Sponsors Ortho Pharmaceutical " Stiefel Galderma Hoechst-Roussel Pharmaceuticals, Inc,