ARTICLE
It has been recognized that the local immune response via the
cytokine network plays an important role in the pathogenesis of psoriasis.
Recent studies have focused on the mechanisms of entry of inflammatory
cells into the site of inflammation in psoriasis [1, 2]. It is thought
likely that increased expression of endothelial leucocyte adhesion molecule-1
(E-selectin) on endothelial cells is responsible for the preferential
recruitment of skin-homing, memory T cells into inflammatory sites [3].
Intercellular adhesion molecule-1 (ICAM-1) is also important not only
in endothelial adhesion but also keratinocyte-leucocyte interactions in
inflammatory dermatoses [4]. Immunolocalization of adhesion molecules
in the lesional skin of psoriasis vulgaris or psoriatic arthritis has
been recently examined [5-7]. Elevated circulating soluble ICAM-1 (sICAM-1)
and sE-selectin levels have been demonstrated in patients with severe
psoriasis, which correlate with disease severity [8] and which decrease
following successful treatments although this is still controversial [9-14].
Generalized pustular psoriasis (GPP) represents an acute, systemic form
of psoriasis, characterized by widespread, numerous, shallow, sterile,
pustules on a base of erythema. However, the pathogenesis of pustule formation
in GPP has not been fully identified. In this study, we have studied immunohistological
localization of ICAM-1 and E-selectin in the lesional skin of GPP, and
measured the circulating levels of these adhesion molecules in patients
with GPP.
Materials and methods
Patients
Six patients with GPP (3 women and 3 men), who were treated and followed-up
in our department, were enrolled in this study. The patients had a mean
age of 58.4 years (age range: 37-70 years). Serum samples were taken when
the patients presented at our clinic for the first time. Aliquots of serum
were frozen at 80° C, prior to use.
Immunohistochemical studies
Biopsy specimens were obtained from the pustular lesions on the trunk
or extremities of the patients. Specimens in OCT compound were immediately
snap-frozen in liquid nitrogen, and 5 µm thick sections were prepared
on PL-lysin coated slides. They were air-dried for 24 h at room temperature.
To block the endogeneous peroxidase activity, the sections were treated
with methanol containing 0.3% hydrogen peroxidase for 15 min at room temperature
and washed in 0.01 M phosphate-buffered saline (PBS). They then were stained
using a standard avidine-biotin peroxidase technique (Nichirei Co. Tokyo,
Japan) with anti-ICAM-1 monoclonal antibody (R&D Systems, Minneapolis,
MN) and anti-E-selectin monoclonal antibody (R&D Systems, Minneapolis,
MN). The sections were developed with 3,3'-diaminobenzidine solution as
chromogen. They were counterstained with hematoxylin, dehydrated, cleared
and mounted. Negative controls were prepared by omission of the specific
antibody, and by its substitution with a non-specific IgG subclass mix
antibody at the dilution used for the specific antibodies in this study.
Three normal skin specimens and three psoriasis vulgaris specimens were
used as a control.
Serum adhesion molecule assays
The concentrations of sICAM-1 and sE-selectin were determined using
an enzyme-linked immunosorbent assay (ELISA) kit (sICAM-1; ICAM-1 ELISA
kit, Bender Med Systems, Vienna, sE-selectin; soluble E-selectin ELISA
kit, R&D Systems, Mineapolis). Six age- and sex-matched healthy controls
and 4 patients with severe plaque-type psoriasis vulgaris with a PASI
score of more than 20 (mean PASI score; 25.4) were also examined.
Statistical analysis
Statistical analysis was performed using Student's t test. Correlation
between sICAM-1 and E-selectin was analyzed with Pearson's correlation
coefficient.
Results
Expressions of ICAM-1 and E-selectin in lesional
skin specimens from patients with GPP
ICAM-1 was expressed on blood vessels throughout the dermis with preferential
expression in the papillary dermis, inflammatory cells, and focally grouped
keratinocytes below the microabscess (Fig.
1, A and B).
E-selectin expression was less extensive and was strongly detected on
blood vessels in the papillary and upper dermis, but was not observed
on keratinocytes (Fig. 1C).
In the involved skin of psoriasis vulgaris, ICAM-1 was detected throughout
the dermal vessels, inflammatory cells, and the upper keratinocytes focally,
whereas E-selectin was expressed in the endothelial cells in the subpapillary
to mid-dermal vessels (data not shown). In normal skin and uninvolved
skin, minimal staining for E-selectin was noted on dermal, vascular, endothelial
cells in the upper dermis. ICAM-1 was constitutively expressed on dermal,
vascular, endothelial cells, however, there was no expression on keratinocytes.
ELISA assays
In patients with severe psoriasis vulgaris, median sICAM-1 (328 ±
21.7 ng/ml) and sE-selectin (83.8 ± 26.0 ng/ml) levels were significantly
elevated compared with control subjects (sICAM-1; 170.5 ± 60.3, p
< 0.01, sE-selectin; 41.5 ± 15.3, p < 0.01) (Fig.
2). In patients with GPP, sICAM-1 (426.9 ± 87.1) and sE-selectin
(106.2 ± 32.8) was higher than that of normal controls (sICAM-1;
p < 0.005, sE-selectin; p < 0.005). Mean levels of sICAM-1 in patients
with GPP were significantly higher than those in patients with psoriasis
vulgaris (p < 0.05), however there was no significant difference in
the level of sE-selectin between patients with GPP and those with psoriasis
vulgaris.
sICAM-1 and sE-selectin levels correlated significantly (R2
= 0.65, p < 0.01) in patients with PV and GPP (Fig.
3).
Discussion
Recruitment of inflammatory cells into the dermis in cutaneous inflammation
depends on their initial attachment to vascular endothelium and later
adherence to the intercellular matrix and to dermal cells. This process
requires interaction between cytokine-inducible, cell-surface adhesion
molecules on resident skin cells and their inflammatory cell ligands.
Immunohistochemical studies have shown the increased expression of several
adhesion molecules in the lesional skin of psoriasis [5-7], which reflects
an ongoing local immune response accompanied by a frequent influx of inflammatory
cells into the lesional skin.
ICAM-1 is not constitutively expressed on keratinocytes
in normal skin. In the actively inflammed skin in psoriasis, ICAM-1 is
demonstrated not only on endothelial cells but also on keratinocytes [5-7],
suggesting that this molecule may play a role in intercellular adhesion
within an inflammatory infiltrate [15]. In psoriasis vulgaris, E-selectin-positive
endothelial cells are observed in close proximity to lesional epidermis,
which has been linked to neutrophil migration and diapedesis [16]. In
the present study, we have demonstrated that ICAM-1 and E-selectin were
definitely expressed on endothelial cells in the papillary and subpapillary
dermis of the lesional skin of psoriasis vulgaris and GPP. ICAM-1 was
focally expressed on keratinocytes in the involved skin of psoriasis vulgaris,
and it is of note that ICAM-1-positive grouped keratinocytes were detected
in the epidermis of lesional skin below the subcorneal abscess in GPP.
The migration of neutrophils from the dermal papilla into the psoriatic
epidermis is explained by the concept of the squirting papilla. GPP demonstrates
numerous superficial pustules which histologically show a subcorneal abscess.
The focal expression of ICAM-1 on keratinocytes might be the targets in
the chemotaxis of inflammatory cells towards the epidermis [17]. ICAM-1
expression in keratinocytes is induced by interferon-gamma (IFN-gamma)
and tumor necrosis factor-alpha (TNF-alpha) [18, 19], which may be involved
in the induction of GPP. Our results indicate that these adhesion molecules
play a crucial role in the initiation and maintenance of pustular lesions
in patients with GPP. Yokochi et al. [20] have recently reported
that ICAM-1-positive keratinocytes were grouped focally in the epidermis
of only lesional skin in palmoplantar pustulosis (PPP), which is a localized
variant of GPP. The infiltration of ICAM-1-positive epidermis by neutrophils
may initiate the formation of the pustule. However, epidermal expression
of ICAM-1 is not a primary inducer of cutaneous inflammation in transgenic
mice [21]. ICAM-1-positive keratinocytes might represent only the result
of inflammation, and other chemotactic factors such as IL-8, C5a, or RANTES
may be key elements in the induction of the pustules of GPP [22]. We are
now investigating the role of such chemokines in GPP.
We have recently shown increased serum levels of soluble ICAM-1 in patients
with severe psoriasis, which decreased following successful cyclosporine
treatment [14]. Carmona et al. [9] have recently shown that post-therapeutic,
circulating levels of sE-selectin showed a significant decrease compared
with pre-treatment levels but remained significantly elevated compared
with healthy controls. This study also demonstrated that circulating serum
levels of ICAM-1 and E-selectin are significantly elevated in GPP. Up-regulation
or induction by cytokines of ICAM-1 and E-selectin occurs in inflammed
skin and parallels the influx of inflammatory cells, suggesting an important
pathogenetic role. However, Groves et al. [23] have shown that
circulating adhesion molecule levels are significantly elevated in erythroderma
associated with psoriasis and eczema. They speculate that increased levels
of circulating adhesion molecules may contribute to the immunosuppressive
state in patients with erythroderma. Our study showed a discrepancy between
the intensity of the local expression of these adhesion molecules and
the serum levels of these molecules, which may suggest that the extent
of local expression of these molecules did not directly reflect on the
increased levels of these circulating soluble molecules. Elevated levels
of these circulating adhesion molecules may reflect the erythrodermic
condition in GPP.
REFERENCES
1. Nickoloff BJ. The cytokine in psoriasis. Arch Dermatol 1992;
126: 1-9.
2. Wakita H, Takigawa M. E-selectin and vascular cell adhesion molecule-1
are critical for initial trafficking of helper-inducer/memory T cells
in psoriatic plaques. Arch Dermatol 1994; 130: 457-63.
3. Shimizu Y, Shaw G, Graber N, et al. Activation-independent
binding of human memory T cells to adhesion molecule ELAM-1. Nature
1991; 349: 799-802.
4. Griffiths CEM. Cutaneous leukocyte trafficking and psoriasis. Arch
Dermatol 1994; 130: 494-9.
5. Griffiths CEM, Voorhees JJ, Nickoloff BJ. Characterization of intercellular
adhesion molecule-1 and HLA-DR expression in normal and inflammed skin:
modulation by recombinant gamma interferon and tumor necrosis factor.
J Am Acad Dermatol 1989; 20: 617-29.
6. Singer KH, Tuck DT, Sampson HA, Hall RP. Epidermal keratinocytes
express the adhesion molecule intercellular adhesion molecule-1 in inflammatory
dermatoses. J Invest Dermatol 1989; 92: 746-50.
7. Schopf RE, Naumann S, Rehder M, Morsches B. Soluble intercellular
adhesion molecule-1 levels in patients with psoriasis. Br J Dermatol
1993; 128: 34-7.
8. Kowalzick K, Neuber M, Weichenthal I, et al. Elevated serum-soluble
ELAM-1 levels in patients with severe plaque-type psoriasis. Arch Dermatol
Res 1994; 286: 414-6.
9. Carmona C, Pineyro I, Martinez M, Macedo NA. Soluble E-selectin levels
in psoriatic patients treated with cyclosporin. Eur J Dermatol
1996; 6: 297-9.
10. Cauducci M, Mussi A, Bonifati C, Fazio M, Ameglio F. sICAM-1, sIL-2R
and beta2-microglobulin serum levels in patients affected with psoriasis:
relationship with disease severity. Arch Dermatol Res 1994; 286:
420-1.
11. Ameglio F, Bonifati C, Carducci M, Alemanno L, Sacerdoti G, Fazio
M. Soluble intercellular adhesion molecule-1 and procollagen peptide are
reliable markers of disease severity in psoriasis. Acta Derm Venereol
(Stockh) 1994; 186 (suppl.): 19-20.
12. Kowalzick L, Bildau H, Neuber K, Kohler I, Ring J. Clinical improvement
in psoriasis during dithranol/UVB therapy does not correspond with a decrease
in elevated serum soluble ICAM-1 levels. Arch Dermatol Res 1993;
285: 233-5.
13. Kowalzick L, Weichenthal M. Serum levels of sICAM-1, sELAM-1 and
sIL-2R in patients with severe psoriasis: no relationship with disease
activity. Arch Dermatol Res 1994; 286: 422.
14. Yamamoto T, Kimura K, Katayama I, et al. Beneficial clinical
effects of cyclosporin A on severe psoriasis and its dissociation from
serum concentration of soluble interleukin-2 receptor, soluble interleukin-6
receptor, soluble CD14 antigen, soluble intercellular adhesion molecule-1,
and soluble vascular cell adhesion molecule-1. Arch Dermatol Res
(in press).
15. Dustin ML, Singer KH, Tuck DT, Springer TA. Adhesion of T lymphoblasts
to epidermal keratinocytes is regulated by interferon-gamma and is mediated
by intercellular adhesion molecule-1 (ICAM-1). J Exp Med 1988;
167: 1323-40.
16. Groves RW, Allen MH, Barker JNWN, et al. Endothelial leucocyte
adhesion molecule-1 (ELAM-1) expression in cutaneous inflammation. Br
J Dermatol 1991; 124: 117-23.
17. Baker JNMN, Mitra RS, Griffiths CEM, Dixit VM, Nickloff BJ. Keratinocytes
as initiators of inflammation. Lancet 1991; 330: 211-4.
18. Norris DA. Pathomechanisms of photosensitive lupus erythematosus.
J Invest Dermatol 1993; 100: 58S-68S.
19. Norris DA. Cytokine modulation of adhesion molecules in the regulation
of immuologic cytotoxicity of epidermal targets. J Invest Dermatol
1990; 95: 111S-20S.
20. Yokochi K, Tamada Y, Takama H, Ikeya T, Ohashi M. Role of adhesion
molecules in the development of pustular lesions in patients with pustulosis
palmaris et plantaris. Acta Derm Venereol (Stockh) 1996; 76: 118-22.
21. Williams IR, Kupper TS. Epidermal expression of intercellular adhesion
molecule-1 is not a primary inducer of cutaneous inflammation in transgenic
mice. Proc Natl Acad Sci USA 1994; 91: 9710-4.
22. Takematsu H, Tagami H. Quantification of chemotactic peptides (C5a
anaphylatoxin and IL-8) in psoriatic lesional skin. Arch Dermatol
1993; 129: 74-80.
23. Groves RW, Kapahi P, Barker JNWN, Haskard DO, Mac Donald DM. Detection
of circulating adhesion molecules in erythrodermic skin disease. J
Am Acad Dermatol 1995; 33: 32-6.
|
Printable version
