© 2008

The International Society of Dermatology International Journal of Dermatology

2008,

47

, 1177–1183

1177

Abstract

Insulin-like growth factor (IGF) and its binding proteins (BPs) are candidates to play a role in the

pathogenesis of psoriasis. IGF-I and -II and their binding proteins (IGFBPs) have both growth

inhibitory and mitogenic effects on a multitude of cell types. Current studies have explored the

potential role of IGFBP-3 in keratinocyte growth and differentiation. To gain more insight into

the role of IGFBP-3 in the pathogenesis of psoriasis, we investigated the changes in IGFBP-3

expression levels in psoriatic plaque and compared these expressions with levels in other

inflammatory skin diseases. In particular, we investigated whether or not the changes in IGFBP-

3 were affected by systemic treatment with cyclosporine A (CsA) or methotrexate (Mtx). We

found significantly increased IGFBP-3 expression levels in the psoriatic group compared with

levels in patients with other, nonproliferative inflammatory skin diseases, and we demonstrated

differences in distribution pattern before and after systemic treatment with Mtx or CsA. Mtx and

CsA had no effect on tissue IGFBP-3 expression levels. Before treatment with Mtx or CsA,

IGFBP-3 expression was limited to the basal layer and suprapapillary region. Unlike with Mtx,

CsA significantly changed the IGFBP-3 distribution pattern.

Blackwell Publishing LtdOxford, UKIJDInternational Journal of Dermatology0011-90591365-4632© 2008 The International Society of DermatologyXXX

Clinical trial

IGFBP-3 expression level in psoriatic tissueÖzden

et al. CLINICAL TRIAL

Increased insulin-like growth factor binding protein-3 expression level in psoriatic tissue before and after systemic treatment with cyclosporine A and methotrexate

Müge Güler Özden,

MD

, Nilsel

I

lter,

MD

, Özlem Erdem Suer,

MD

, Nilgün Solaktekin,

MD

, and Mehmet Ali Gürer,

MD

From the Medical Faculty, Dermatology Department, Ondokuz Mayis University, 55139, Kurupellit, Samsun, Turkiye

Correspondence

Müge Güler Özden,

MD

Faculty of MedicineDepartment of DermatologyOndokuz May

&

s UniversityKurupelit, SamsunTurkeyE-mail: mozden@omu.edu.tr

Introduction

Growth hormone, insulin-like growth factor (IGF) and itsbinding proteins (BPs) have been suggested as candidates toplay a role in the pathogenesis of psoriasis. IGF-I receptor isoverexpressed in psoriatic-involved skin and the keratinocytesfrom nonlesional psoriatic skin have an increased responseto IGF-I.

1,2

IGF-I and IGF-II and their binding proteins(IGFBP-1–6) have diverse mitogenic and differentiationeffects on a multitude of cell types. The actions of the IGFs instimulating growth and differentiation in a wide variety ofcell types have been shown in the literature.

3

IGF-I acts as aprogression factor in the cell cycle and synergizes with com-petence factors such as platelet derived growth factor andfibroblast growth factor.

4

It has also been shown that IGF-Istimulates terminal myogenic differentiation of myoblasts.

5

Six high-affinity specific BPs modulate the bioavailability ofIGFs to interact with their receptors. The majority of IGF-I isbound to IGFBP-3, in serum and epidermis.

6,7

IGFBP-3 is amajor carrier in human circulation for IGF-I and -II, theactions of which may be inhibited and/or enhanced.

8

IGFBP-3 both protects IGF-I from degradation and lowers its freeconcentration.

9

One suggested function of the ternary IGFBP-

3 complex is to provide a pool of bioavailable IGF-I.

10

In addi-tion, IGFBP-3 may be proteolytically modified, reducing itsaffinity for IGF-I and thus further diminishing the capacityfor circulating IGF-I reserves.

11

IGFBP-3, known to possessboth IGF-dependent and -independent activity, is expressedexclusively by the selected basal keratinocytes.

12,13

Studies inthe literature have explored the potential role of IGFBP-3 inkeratinocyte growth and differentiation.

14,15

To gain moreinsight into the role of IGFBP-3 in the pathogenesis of psoriasis,we designed a study to clarify the changes in IGFBP-3 expres-sion levels in psoriatic plaque and to compare these expres-sion levels with those in other inflammatory skin diseases. Inparticular, we explored whether the changes in IGFBP-3 wereaffected by systemic treatment with cyclosporine A (CsA) ormethotrexate (Mtx).

Materials and Methods

Patients with chronic plaque psoriasis with no ongoing psoriasis

treatment were selected from the outpatient clinic of the

Department of Dermatology, Gazi University Hospital. Patients

provided their informed consent after the study had been fully

explained, and the study was approved by the ethics committee of

International Journal of Dermatology

2008,

47

, 1177–1183 © 2008

The International Society of Dermatology

1178 Clinical trial

IGFBP-3 expression level in psoriatic tissue

Özden

et al.

Gazi University Medical Faculty. The inclusion criteria were

continuous disease persisting for longer than 6 months, no topical

therapy for 4 weeks, no systemic therapy for 8 weeks, and the

existence of active psoriasis with psoriasis area and severity index

(PASI) scores above 15. None of the subjects was using any

medication and none was pregnant. Psoriatic patients were

allocated to two groups of 15 according to treatment with either

CsA (Group 1) or Mtx (Group 2). IGFBP-3 was studied in tissue

samples before and after both treatments. Groups 3 and 4

included patients with generalized eczema/nummular dermatitis

(

n

=

17) and pityriasis rosea (

n

=

13), respectively, as

representatives of nonhyperproliferative inflammatory skin

diseases. We considered the pretreatment samples from the

psoriasis patients as the main control group demonstrating the

effects of both treatment reagents. We also included the other

nonproliferative inflammatory skin disease patients to investigate

the etiopathogenesis of psoriasis. Control groups and patients with

psoriasis received no topical treatment except moisturizers.

Ages of patients in Groups 1 (

n

=

15) and 2 (

n

=

15) ranged from

20 to 60 years (mean: 36.9

±

9.6) and 22–66 years (mean:

39.0

±

9.4), respectively. These values in Groups 3 (

n

=

17) and 4

(

n

=

13) were 25–58 years (mean: 40.94

±

9.64) and 21– 49 years

(mean: 32.77

±

10.80), respectively. The pretreatment values of

IGFBP-3 obtained in psoriatic Groups 1 and 2 were also compared

with those obtained from Groups 3 and 4, and after treatment with

Mtx and CsA.

Procedure and clinical outcomes

During the first visit of each patient in the acute phase of psoriasis,

a detailed history was taken and a thorough clinical examination

performed. One solitary plaque was selected as target lesion.

Group 1 patients were treated with CsA and Group 2 patients with

Mtx. Apart from routine biochemical investigations in patients and

controls, 100 incisional biopsies were also obtained from target

psoriatic plaques and from a corresponding area of the target

lesion after treatment. Biopsies were obtained from the lesional

skin only once in Groups 3 and 4. Prior to biopsy, local anesthesia

was given (1% lidocaine without epinephrine). Skin defects were

closed with one suture. To exclude potential Koebner effect on the

post-treatment samples, we did not excise the biopsies from the

same location. We used corresponding regions at least 2 cm away

from the first sample location. At each visit, the PASI score was

assessed. All patients were given standard treatments depending

upon the severity and clinical response of the disease, including

CsA and Mtx. The IGFBP-3 expression levels and distribution

patterns were evaluated in tissue samples.

Immunohistochemistry

Immunohistochemical staining was performed on routinely

processed formalin-fixed paraffin-embedded tissues. A 4-

μ

m thick

section from tissue blocks were stained with anti-IGFBP-3

antibody (SC-6003; Santa Cruz Biotechnology, Santa Cruz, CA).

Sections were deparaffinized under 56

°

C for 12 h and dehydrated

with xylene and 100% alcohol. Endogenous peroxidase activity

was blocked with 3% hydrogen peroxide for 10 min at room

temperature. Sections were treated with anti-IGFBP-3 antibody at

room temperature for 2 h. Sections were washed with phosphate-

buffered saline and embedded in avidin–biotin-peroxidase reagent

for 10 min. DAB (3,3

′

-diaminobenzidine) was used as chromogen.

Quantification

Quantification of IGFBP-3 was performed at

×

400 magnification;

IGFBP-3 positive cells in the epidermis were counted from the

basement membrane up to the stratum corneum across the whole

section. Quantitative cell counts were expressed as “positive

keratinocytes/all keratinocytes (percentage)”. All slides were

reviewed in total at the end of the study by one of the authors (OE)

who was unaware of the clinical findings and treatment modality of

the patients.

Statistical analysis

The ratio of gender of groups were compared by Pearson’s

χ

2

-test.

The data for the demographic properties (such as age and

duration of the disease) of four groups of patients were tested for

normality by using Kolmogorow–Smirnow test. Age data was

normal but duration of disease was not normally distributed.

Groups were compared for age data by one way

anova

, and the

data for duration of the disease of Groups 1 and 2 were compared

by Mann–Whitney

U

-test. Results were expressed as the mean

±

SD, median (min, max) values.

T

-test, Mann–Whitney U and

Wilcoxon tests were used to compare immunohistochemical

parameters.

P

-values of

<

0.05 were considered statistically

significant. All analyses were performed using

SPSS

version 13.0.

Results

Patient population

The age of the patients in Group 1 (

n

=

15) and 2 (

n

=

15) rangedfrom 20 to 60 y and 22–66 y, with a mean age of 36.9

±

9.6and 39.0

±

9.4, respectively. The age of the patients in Groups3 and 4 ranged from 25 to 58 years and 21 to 49 years, witha mean age of 40.94

±

9.64 years and 32.77

±

10.80 years,respectively. The groups were similar in demographiccharacteristics of age (

P

=

0.197), of gender (

P

=

0.977), andduration of the disease (

P

=

0.345). Patients in Group 1 weresubsequently treated with CsA 150–300 mg/d (mean: 22.6

±

41.6) for 30–160 d (mean: 56.6

±

33.1). CsA dose was tapered50 mg per 2 weeks as soon as clinical improvement in psoriasiswas observed. Patients in Group 2 were treated with 20 mgMtx 2 d/week for approximately 9.8

±

5.4 weeks (range: 6–24). The cumulative Mtx dosage was 199.3

±

107.9 mg(range: 120–480). The PASI scores at baseline were21.1

±

4.2 and 19.6

±

5.0, declining to 1.2

±

1.2 and 1.4

±

1.1after therapy, respectively. The PASI scores were not statisti-cally different between the two psoriasis groups (

P

=

0.764).

© 2008

The International Society of Dermatology International Journal of Dermatology

2008,

47

, 1177–1183

1179

Özden

et al. IGFBP-3 expression level in psoriatic tissue

Clinical trial

IGFBP-3 expression levels

When the biopsies from psoriatic lesions were incubated inIGFBP-3 antibody, a marked increase in specific labeling wasobserved compared to Groups 3 and 4 (

P

=

0.05, 0.008;Mann–Whitney

U

). Mean IGFBP-3 counts per millimetersection length as percent are depicted in Fig 1. The epidermisof untreated psoriatic skin of Groups 1, 2 and lesional skin of

Groups 3, 4 showed counts of 40.67

±

28.40 (range: 0–80,median: 40), 40.00

±

33 (range: 0–80, median: 40), 30

±

25.92 (range: 0–80, median: 20) and 12

±

21.22 (range: 0–80, median: 5), respectively. We observed that the pityriasisrosea cases (Group 4) showed a significantly lower level ofIGFBP-3 expression than the other samples of patients witheczema (Group 3) (

P

=

0.008; Mann–Whitney

U

). IncreasedIGFBP-3 expression levels were not statistically decreasedafter treatment with CsA or Mtx (

P

=

0.902; 0.389; Wilcoxonsigned ranks test). Additionally, IGFBP-3 expression levelsremained significantly higher compared with Groups 3 and 4(

P

=

0.42, 0.009; Mann–Whitney

U

). At the end of treatment,no statistically significant difference was found between thetwo psoriasis groups with respect to IGFBP-3 expressionlevels [47.3

±

26.63 (range: 0–80, median: 40) and 38.0

±

30.28 (range: 0–80, median: 30), respectively;

P

=

0.215;Mann–Whitney

U

] (Table 1).

IGFBP-3 distribution pattern

We observed that IGFBP-3 was most dense in the basallayer and suprapapillary region in both psoriatic groups atbaseline (Figs 2,3). Baseline IGFBP-3 was strictly localized tothe basal layer in 4 (26.6%) and 5 (33.3%) patients in Groups1 and 2, respectively, and to both basal layer and suprapapil-lary region in 10 patients (66.6%) in each group. One patientin Group 1 showed IGFBP-3 localization in all layers of theepidermis. In Group 3, IGFBP-3 distribution was seen in thebasal layer of epidermis in 10 (58.8%) and in all layers in 7(41.2%) patients. In Group 4, distribution was basal layerlocalization in 4 (30.7%) and all epidermal layers in 9(69.2%) (Fig. 4). After CsA treatment, the polarization ofIGFBP-3 distribution pattern was significantly changed,appearing in all layers of epidermis, similar to the distributionpattern of Group 4 [basal layer localization

n

=

2 (13.3%), allepidermal layers

n

=

13 (86.6%)] (Fig. 5). However, there wasno significant change in the distribution pattern followingMtx treatment (Fig. 6). IGFBP-3 was detected in basal layerin 12 (80%) patients and in all layers of epidermis in 3 (20%)patients in this group (Table 1).

Figure 1 Elevated IGFBP-3 levels in tissue samples from the psoriatic lesions before and after treatment with CsA and Mtx and Group 3 as percent. “The superior and the inferior lines of the bars are the 75th and the 25th percentiles, respectively. The transverse lines are the median values of the groups”. 1IGFBP-3 levels in psoriatic tissue before CsA treatment, 2IGFBP-3 levels in psoriatic tissue after CsA treatment, 3IGFBP-3 levels in psoriatic tissue before Mtx treatment, 4IGFBP-3 levels in psoriatic tissue after Mtx treatment, 5IGFBP-3 levels in group 3 (the patients with other, nonproliferative inflammatory skin diseases), 6IGFBP-3 levels of pytriasis rosea cases in group 3. *Carrying different numbers of asterisks are significantly different from each other

Table 1 Expression level and distribution pattern of IGFBP-3 in each group

Expression level Before treatment After treatment P

Group 1 40 ± 28.4 47.3 ± 29.6 0.433Group 2 40.0 ± 33 38.0 ± 30.2 0.752Group 3 30 ± 25.92 – –Group 4 12 ± 21.22 – –Distribution pattern Basal ++++ suprapapillary All epidermal Basal ++++ suprapapillary All epidermalGroup 1 93.2% (n = 14) 6.8% (n = 1) 13.3% (n = 2) 86.6% (n = 13) 0.18Group 2 100% (n = 15) 80% (n = 12) 20% (n = 3) 0.157Group 3 58.8% (n = 10) 41.2% (n = 7) – – –Group 4 30.7% (n = 4) 69.2% (n = 9) – – –

International Journal of Dermatology 2008, 47, 1177–1183 © 2008 The International Society of Dermatology

1180 Clinical trial IGFBP-3 expression level in psoriatic tissue Özden et al.

Discussion

There are many conflicting results regarding the biologicaleffects of IGF-I and -II, and the question of whether IGFBP-3plays a functional role in the pathogenesis of psoriasis is con-troversial.1,16–19 IGF-I is a potent mitogen of epidermal kerat-inocytes and is essential for the normal growth of theepidermis.19–22 Keratinocytes isolated from psoriatic patients,even from uninvolved skin, were found to be more susceptibleto IGF-I stimulation than keratinocytes from unaffectedhealthy individuals.2 Increased bioactivity of IGF-I by IGFBP-3 was demonstrated in a study where systemically adminis-tered IGF-I complexed with IGFBP-3 had greater effects onwound healing compared with equivalent amounts of IGF-I

alone.23 It is believed that IGFBP-3 prolongs the half-life ofIGF-I in serum and at a cellular level modulates the access ofIGFs to their receptors. It has been shown that IGF-I receptorsare rapidly decreased in the absence of IGFBP-3. This meanstissue IGFBP-3 plays a key role in the maintenance of IGF-Ireceptors.24

In this study, we investigated changes in the psoriaticplaque. In particular, we explored whether the changes inIGFBP-3 were specific for psoriasis or relevant in other skindiseases without hyperproliferation as well. We compared theresults before and after treatment with CsA or Mtx and foundsignificantly increased IGFBP-3 expression levels in the psori-atic group compared with the patients with other, non-proliferative inflammatory skin diseases (eczema and pityriasisrosea). We also investigated the distribution pattern before

Figure 2 IGFBP-3 expression limited to basal and suprapapillary region before treatment with CsA, in psoriatic tissue. (×400 DAB chromogen)

Figure 3 IGFBP-3 expression limited to basal and suprapapillary region before treatment with Mtx, in psoriatic tissue. (×100 DAB chromogen)

Figure 4 IGFBP-3 expression in other, nonproliferative inflammatory skin disease patients (×400 DAB chromogen)

Figure 5 IGFBP-3 expression in all epidermal layers after treatment with CsA. (×400 DAB chromogen)

© 2008 The International Society of Dermatology International Journal of Dermatology 2008, 47, 1177–1183

1181Özden et al. IGFBP-3 expression level in psoriatic tissue Clinical trial

and after systemic treatment with Mtx or CsA. We foundno other study in the literature that investigates the effect ofsystemic treatments on IGFBP-3 expression level and distri-bution pattern. IGFBP-3 plays various roles in different celltypes, including enhancing or inhibiting cell survival, withor without dependence on IGFs.25,26 Our results support analtered regulation of tissue IGFBP-3 in psoriasis, which wassuggested by other authors before.1,2,20,27 Before treatmentwith Mtx or CsA, IGFBP-3 expression was limited to the basaland suprapapillary region. Interestingly, in three psoriatictissue samples, IGFBP-3 was detected in all layers of theepidermis. CsA and Mtx had no effect on tissue IGFBP-3expression levels. However, CsA significantly changed theIGFBP-3 distribution pattern. After CsA treatment, thepolarization of IGFBP-3 distribution pattern was significantlychanged, appearing in all layers of epidermis, and comparableto the distribution observed in Group 4. There was no signifi-cant change in the distribution pattern with Mtx treatment.IGFBP-3 was detected in the basal layer in 80% of patientstreated with Mtx. Mtx is a synthetic analog of folic acid. Theinhibition of thymidylate synthesis appears to be the mostimportant effect exerted by Mtx, which results in inhibitionof DNA synthesis and arrest of cell division in the S-phase.Mtx inhibits replication and function of T and B cells andsuppresses the secretion of various cytokines such as inter-leukin (IL)-1, interferon-γ and tumor necrosis factor (TNF).Mtx has immunosuppressive effects and it suppresses epidermalcell proliferation.28–30 CsA induces immunosuppression byinhibiting the first phase of T cell activation. CsA binds tocyclophilin and then binds to calcineurin. Calcineurin inhibi-tion, in turn, results in blockage of signal transductionpathways of activated T cells. Ultimately, the production ofcytokines that are important in cell-mediated immunity, such

as IL-2, 3, 4, granulocyte-macrophage colony-stimulatingfactor (GM-CSF), TNF-α and interferon-γ, is inhibited.28 Wecan speculate that these results support the more specific actionmechanism of CsA in the pathogenesis of psoriasis, relatedwith IGFBP-3 mechanisms. In psoriatic skin lesions, as innormal skin, the actively dividing keratinocytes are limited tothe first 2–3 rows of cells in the basal layer, the epidermal celllayer closest to the basal lamina.31,32 Edmonson et al. indi-cated that the highest levels of IGFBP-3 mRNA in humanskin were associated with proliferative keratinocytes of thebasal/germinative layer of the epidermis. They studied thetransgenic mouse model and found that overexpression ofIGFBP-3 in the epidermis was associated with an inhibitionof keratinocyte proliferation and that IGFBP-3 expressionwas strictly localized to selected basal keratinocytes. Theyalso suggested that the absence of IGFBP-3 from proliferativekeratinocytes in psoriatic skin lesions may play a role in thepathogenesis of epidermal hyperplasia.15

Björntorp et al. examined the serum levels of IGF-I andIGFBP-3 in psoriatic patients and found no significant differ-ence between them. However, this result cannot rule out alocal alteration, which is suggested by Xu et al. and was demon-strated in our study.17,27 In 1996, Xu et al. investigated IGFsand IGFBPs in serum and artificially increased blister fluidfrom uninvolved and involved areas of nine patients withpsoriasis. They found that IGF-II but not IGF-I levels weresignificantly elevated. IGFBP-3 levels were also significantlyhigher (1.2-fold) in fluid from the involved areas than in fluidfrom the uninvolved areas. To examine the IGFBP-3 proteaseactivity in lesional areas, they also investigated the intactIGFBP-3 levels and found that the major difference lay in theamount of intact IGFBP-3 but not in the fragmented form.Incubation with fluid from the uninvolved areas resulted in anapparent degradation of the intact IGFBP-3 into fragments,and the remaining intact form was 33 ± 7% of the controlvalue. The extent of such degradation was significantlyreduced when the IGFBP-3 was incubated with matched fluidsfrom the involved areas and the remaining intact formincreased to 81 ± 11% of the control value. In that study, theyshowed that IGFBP-3, but not other IGFBPs, were increasedin fluid from the involved areas, and they suggested that thiswas due to both elevated IGFBP-3 level and decreased IGFBP-3 proteolytic activity. Increased IGF-II level might affect theIGFBP-3 level as well.27

One year later, Wraight et al. studied the expression ofIGFBP-3 in seven psoriatic patients and normal-healthy con-trols. They found that IGFBP-3, like its mRNA, were presentexclusively in basal keratinocytes of normal skin and werestrictly limited to the suprapapillary epidermis in psoriaticskin. Although Wraight et al. proposed that IGFBP-3 has agrowth inhibitor role in psoriasis, our data does not supportthis theory.17 They also suggested that IGFBP-3 is one of themost specific markers of basal keratinocyte proliferation,

Figure 6 IGFBP-3 expression limited to basal and suprapapillary region after treatment with Mtx, in psoriatic tissue. (×100 DAB chromogen)

International Journal of Dermatology 2008, 47, 1177–1183 © 2008 The International Society of Dermatology

1182 Clinical trial IGFBP-3 expression level in psoriatic tissue Özden et al.

because existing markers of basal keratinocytes fail to main-tain a basal localization in hyperproliferative epidermis.

There are contradictory results in the literature regardingthe functions of IGFBP-3. This complex event may be explainedby different cell culture study designs and the multifunctionalactivity of IGFBP-3. By comparing normal human keratinocytes(NHKs) with an immortalized, ultraviolet (UV) susceptiblehuman keratinocyte cell line (HaCaT), a model of IGF/IGFBP-3 actions in the epidermal UV response was proposed.In comparison to NHKs, HaCaT keratinocytes exhibitedhigher levels of UV-induced apoptosis, refractoriness to IGF-I treatment and reduced IGF-I receptor phosphorylation. Apro-survival role for basally located IGF-I receptors followingepidermal UV insult has been implied. Maintenance of intactIGFBP-3 abundance and the presence of IGFBP-3 fragmentsin NHKs, in comparison to HaCaT keratinocytes, followinghigh UVB exposure suggests that a delicate balance may existbetween “pro-survival” intact IGFBP-3 and “proapoptotic”IGFBP-3 fragments. Intact IGFBP-3 would promote keratino-cyte survival via targeting of IGF-I ligand to IGF-I receptorsor via IGF-independent mechanisms. In contrast, UV-inducedIGFBP-3 fragments may contribute to epidermal UV-inducedapoptosis. In this model, IGFBP-3 exhibits multifunctionalactivity.33,34

These conflicting results were also problematic in otherdiseases such as prostate and breast cancer and others. Ingeneral, high levels of IGFBP-3 in breast tumor specimenswere associated with unfavorable prognosis, despite thedemonstrated antiproliferative and pro-apoptotic activity ofIGFBP-3 in many in vitro studies.35,36 This suggests that somemalignancies can escape from the growth-inhibitory effects ofIGFBP-3, or even become stimulated by it, as demonstrated invitro. Because the IGF-IGFBP system is recognized as centralto processes of cell growth, differentiation and migration,there is an effort to understand the relationship betweeninhibitory and stimulatory actions of IGFBP-3 and otherIGFBPs on these cellular processes. Furthermore, there is theprospect of clinical applications based on the IGFBPs.25

In this study, we found significantly elevated tissue IGFBP-3 expression levels in psoriatic patients compared to thosewith other, nonproliferative inflammatory skin diseases. Thisalteration did not change after systemic treatment with Mtxor CsA. While Mtx had no effect on the distribution patternof IGFBP-3, CsA changed this pattern.

In conclusion, we suggest that IGFBP-3 may play a multi-functional role in the etiopathogenesis of keratinocyte hyper-proliferation in psoriasis. The properties of IGFBP-3 warrantfurther investigation.

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