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*
Arthritis and Rheumatism Branch, National Institute of Arthritis, Musculoskeletal and Skin Diseases, and
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
Department of Clinical Pathology, Warren Grant Magnuson Clinical Center, and
Department of Radiology, National Naval Medical Center, Bethesda, MD 20892
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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v
3 integrin expression on von
Willebrand factor+ vessels were observed. Together these
data demonstrate that a short course of IL-10 modulates immune
responses in vivo via diverse effects on endothelial activation, and
leukocyte recruitment and effector function. Such biological changes
may result in clinically meaningful improvement in disease
activity. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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production (3, 11), can induce
Ag-specific anergy in vitro (12), and may promote the
emergence of regulatory CD4+ T cell subsets
(13). IL-10 can directly modulate endothelial cell
activation and angiogenesis in vitro (14, 15). It reduces
secretion of collagen (16), matrix metalloproteinases
(MMP),4 but not tissue
inhibitors of MMPs (17), which together with effects on
osteoclast differentiation/activation (18), indicates that
IL-10 may retard inflammatory lesion extension and host tissue
destruction.
Psoriatic arthritis (PsA) develops in some 5–25% of patients with
psoriasis. Keratinocyte proliferation and inflammatory infiltration,
with elevated cytokine and chemokine expression, characterize cutaneous
psoriatic lesions. T cell activation, commensurate with an ongoing Th1
phenotype (19, 20), TCR repertoire skewing
(21), and the beneficial clinical effects of T
cell-directed therapies indicate that T cells, driven by local Ag
recognition, play an important role in psoriasis pathogenesis. A
striking feature is the relative absence of antiinflammatory moieties,
including IL-10 and IL-1R antagonist (19, 22, 23, 24).
Effective cutaneous therapies are often associated with reversal of the
cytokine pattern to that of a type 2 phenotype (25, 26).
We recently demonstrated high levels of proinflammatory cytokine
expression and NF-
B activation in PsA synovium, together with
relative paucity of IL-10 expression (27). Evidence for
endothelial cell activation, enhanced adhesion molecule expression,
coupled with proangiogenic activity through vascular endothelial growth
factor, basic fibroblast growth factor, and
v3 integrin
expression, has also been provided in both cutaneous and synovial
lesions (28, 29, 30). Together these observations indicate
that IL-10 administration could be therapeutically beneficial.
Clinical phase I/II studies in normal volunteers, and in rheumatoid arthritis (RA) and Crohn’s disease suggest that human rIL-10 (rhIL-10) is well tolerated (31, 32, 33). An open-label study in psoriasis demonstrated reduction in lesion size following local administration of rhIL-10, associated with the presence of increased Th2-type cytokines in circulating lymphocytes (23). However, significant placebo effects might be anticipated in such a study design, rendering interpretation of in vivo bioactivity difficult. We have now performed a placebo-controlled, dose-escalating study investigating the safety and biological activity of rhIL-10 in PsA. We report that significant immune deviation can be safely achieved by systemic administration of IL-10 to PsA patients. Such immune effects were associated with significant clinical improvements in cutaneous, but not synovial inflammation in the short term.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Twenty-nine patients were submitted to a dose-escalating,
placebo-controlled, phase II study, approved by the Institutional
Review Board, National Institute of Arthritis and Musculoskeletal and
Skin Diseases, National Institutes of Health. Patients
self-administered daily s.c. injections of either placebo, or 1, 5, or
10 µg/kg rhIL-10 (Schering-Plough, Madison, NJ) for 28 consecutive
days. All patients were <18 years of age and provided informed
consent. Entry criteria included: 1) PsA of <6 mo duration, defined as
follows (5, 6, 7, 8, 9, 10, 11, 12, 13, 14): classic psoriatic skin lesion with or
without nail involvement; peripheral arthritis alone or in
combination with spinal disease; negative rheumatoid factor
and absence of s.c. nodules; and radiographic findings compatible with
PsA. 2) Active arthritis with three or more swollen joints considered
capable of responding to drug therapy and at least two of the
following: tenderness or pain on movement of at least three
joints/entheses; at least 45 min of morning stiffness (peripheral
joints or axial); and erythrocyte sedimentation rate (ESR) 
28 mm/h or
C-reactive protein (CRP) <0.8 mg/dl. 3) Failure to respond to or
development of intolerable side effects to at least one
disease-modifying antirheumatic drug.
Low-dose glucocorticoids (
10 mg/day of prednisone or equivalent) and
nonsteroidal antiinflammatory drugs were allowed if doses were stable
for at least 4 wk before randomization and were kept constant for the
study duration. Disease-modifying antirheumatic drugs (methotrexate,
sulfasalazine, gold, hydroxychloroquine, cyclosporin, azathioprine,
cyclophosphamide, chlorambucil), retinoids, and vitamin D were
discontinued 4 wk before randomization. Patients with
seropositive/symmetric polyarthritis, systemic lupus erythematosus or
other autoimmune disease, spondylitic form of PsA (spondylitis alone or
in combination with shoulder and hip arthritis without evidence of
peripheral arthritis), severe physical disability (RA functional class
IV), serum creatinine <1.8 mg/dl or creatinine clearance >50 ml/min,
preexisting malignancy, acute or chronic infections requiring
antimicrobial therapy, or serious viral or fungal infections were
excluded. Pregnant females, nursing mothers, or patients of
childbearing age not practicing birth control were excluded.
Disease activity was evaluated on days 1, 29, 57, and 85, by the same blinded observer throughout, as follows: 1) joint count for tenderness or pain on motion for 84 diarthrodial joints graded 0–3; 2) joint swelling for 74 joints graded 0–3; 3) patient assessment of pain (100-mm linear instrument); 4) patient’s general (global) assessment (100-mm linear instrument); 5) physician assessment of disease activity (100-mm linear instrument); 6) Health Assessment Questionnaire; 7) acute phase response (ESR or CRP); 8) duration of morning stiffness (min); and 9) spinal involvement, assessed by range of motion of cervical and lumbar spine, chest expansion, and sacroiliac pain. Digits with intense inflammatory changes between the joints ("sausage digits") were evaluated by assessment of erythema, warmth (both graded 1–3), and circumference. Skin disease activity was assessed by calculating the psoriasis area and severity index (PASI) (34). For calculation of this, the four main body areas were assessed: the head, trunk, and upper and lower extremities, corresponding to 10, 20, 30, and 40% of the total body area, respectively. To evaluate the severity of the psoriatic lesions, three target symptoms, namely erythema, infiltration, and desquamation, were assessed on a 0–4 scale. To calculate the PASI, the sum of the severity rating for these three main changes was multiplied with the numerical value of the areas involved and with the various percentages of the four body areas. These values were then added to obtain the PASI. The PASI varies in steps of 0.1 U from 0–72, the latter representing complete erythroderma of the highest severity.
Change in disease activity was assessed as follows: 1) significant improvement of joint disease, as defined by American College of Rheumatology (ACR) (35); 2) significant improvement in joint swelling or joint pain/tenderness (improvement by 50% or more in the number of tender/swollen joints); 3) therapeutic remission, as defined by American Rheumatism Association (ARA; now ACR); and 4) significant skin improvement defined as a 35% improvement in the PASI score.
Radiological assessment
Magnetic resonance imaging (MRI; 1.5T General Electric,
Waukesha, WI; Signa Horizon operating with version 5x software) was
performed on d1 and d29. Films were read simultaneously by an
experienced musculoskeletal radiologist and a rheumatologist, blinded
to identity, treatment assignment, and sequence of the films. Capsular
distention, synovial volume, and enhancement were independently graded
on a scale from 0 to 3, and the two values were averaged: 0 =
normal enhancement; 1 = minimal enhancement; 2 = marked
enhancement; 3 = marked enhancement with distended capsule. A
difference 1 between the pre- and posttreatment films therefore
represented clinically meaningful change.
Synovial and skin tissue evaluation
Multiple (at least 10) closed needle synovial biopsies were
obtained at d1 and d29. At the same time, 3-mm punch biopsies of
lesional and perilesional skin (three per site) were obtained. Tissues
were Formalin fixed for H&E staining, or snap frozen for
immunohistological analysis, performed as previously described
(36). Murine mAbs to CD3, CD4, CD8, CD19, CD68, von
Willebrand factor (vWF), ICAM-1 (all DAKO, Carpinteria, CA), VCAM-1,
P-selectin, E-selectin (all Novocastra, Newcastle, U.K.),
v3 integrin
(Chemicon, Temecula, CA), ki67 (DAKO), and cytokeratin 18 (Zymed, San
Francisco, CA) were employed. Briefly, 8 µM acetone-fixed frozen
sections were blocked, then incubated overnight with primary Ab. Bound
Ab was detected with biotinylated goat anti-mouse Ig,
streptavidin-enzyme conjugate, color substrate development, and
hematoxylin counterstain (all DAKO). Alkaline phosphatase was
visualized with new Fuschia and HRP with diaminobenzidine (both from
Vector, Burlingame, CA). Quantification was performed by light
microscopy on an Olympus BX60 optic system, as previously described
(30, 36). Briefly, synovial staining was assessed in
lining layer, sublining, and aggregate areas separately, as was
epidermal and dermal staining in skin. Twelve to sixteen high power
fields (hpf) at x400 magnification, including at least 6 hpf of lining
layer and 6 hpf of sublining layer, were analyzed for each sample by
two observers independently, who were blinded to tissue origin. Skin
epidermal areas were calculated in square micrometers by computer image
analysis using Scion Imaging software (Gaithersburg, MD). Significant
interobserver discrepancy was addressed by reevaluation and mutual
consent.
Evaluation of immunological function
Analyses were performed on days 1, 15, 29, and/or 57. Circulating leukocyte subsets were estimated by FACS analysis (Becton Dickinson, San Jose, CA), using directly conjugated Abs to the following cell surface markers: CD3, CD4, CD8, CD20, CD14, CD56. Cell activation status was determined by FACS using CD28, CD40L, CD69, and HLA-DR expression. Ig subsets (IgG1–4, IgE, IgM, IgA) were measured by nephelometry. Circulating soluble P-selectin, soluble E-selectin, soluble ICAM-1, soluble VCAM-1, TNFRII, IL-18 (all R&D Systems, Minneapolis, MN), IL-12p40 (Endogen, Woburn, MA), and MMP3 (Amersham Life Science, Arlington, IL) were measured by ELISA.
Whole blood cultures were established by diluting heparinized blood 1/5
in IMDM (Life Technologies, Gaithersburg, MD). Cultures in 24-well
plates were immediately stimulated with medium alone, LPS (Sigma, St.
Louis, MO; 1 µg/ml for 16 h) for monokine production, or PHA
(Sigma; 3 µM for 48 h) for T cell cytokine production.
Preliminary dose-response and time-course experiments determined that
these were the optimal time and dose requirements for the cytokines
estimated. Supernatants were stored at -20°C until cytokine
estimation by ELISA, according to the manufacturers’ instructions
(IL-2, IL-4, IL-5, IL-6, IL-10, total IL-12, IL-12p70, IFN-,
TNF-, and IL-1 kits from Endogen; IL-18 from R&D Systems).
Intracellular cytokine expression was measured as previously described
(37). Briefly, PBMCs obtained by density gradient
centrifugation were stimulated for 4 h in RPMI, 10% human serum
(Life Technologies) with PMA (Sigma; 100 nM)/ionomycin (Calbiochem, La
Jolla, CA; 1 µM) in the presence of monensin (Calbiochem; 2 µM).
Intracellular expression of IFN-, IL-4, IL-5, and IL-10 (detected
using conjugated Abs from PharMingen, San Diego, CA) in
CD4+ and CD8+ T lymphocytes
was measured by four-color FACS analysis (Becton Dickinson). In
parallel cultures, expression of the chemokine receptor CCR5 on PBLs
was determined by FACS (PharMingen).
Statistical methods
Categorical outcome measures were compared using a contingency
table and a 
2 test; Fisher’s exact test was
used, as appropriate. Continuous outcome measures were compared by
Student’s t test for parametric variables, and the
Mann-Whitney U test for nonparametric variables. For
pairwise comparisons, paired t test was used for parametric,
and paired sign test for nonparametric variables. Values of
p < 0.05 are considered significant. All statistical
analyses were done with the Statview V.5 statistical software package
(SAS Institute, Cary, NC).
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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). One patient randomized to receive 5
µg/kg IL-10 failed to return for follow-up from day 8. To determine
whether such an administration protocol induced functional immune
deviation, immune parameters in serum, leukocyte cultures, and
synovial/skin tissues were compared in rhIL-10 and placebo recipients.
Three patients received 1 µg/kg IL-10 to establish the safety of
IL-10 in this disease. Because of the small number of patients in this
group, they were not included in subsequent analyses.
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Since IL-10 exerts direct effects on macrophages in vitro, we
first determined cytokine production by LPS-stimulated whole blood
cultures. We compared immunomodulatory effects between cohorts of
rhIL-10- and placebo-treated patients. Dose-dependent suppression of
TNF- and IL-1 synthesis was observed in rhIL-10
(p = 0.0078; Fig. 1a), compared with
placebo-treated patients. Significant inhibition was evident within 14
days and reversed 28 days after discontinuation of therapy (data not
shown). This effect was specific since no consistent effect was
observed on IL-10 synthesis in vitro (Fig. 1c). Serum TNFRII
levels rose dose dependently in rhIL-10 recipients, commensurate with
which the ratio of ex vivo TNF- synthesis to in vivo TNFRII levels
was significantly suppressed (Fig. 2, a and b). Although previous single-dose studies
indicated transient monocytosis, no sustained alteration in
the absolute number or proportion of circulating monocyte subsets was
evident by FACS analysis at day 15 or day 29. Similarly, CD14, HLA
class II, and CD64 expression was comparable in rhIL-10 and placebo
groups. Together, these data indicate selective functional suppression
of the proinflammatory activities of circulating monocytes in rhIL-10-,
but not placebo-treated PsA patients.
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No significant alterations on circulating lymphocytes, including
CD3+, CD4+, and
CD8+ subsets, or on CD69, CD25, CD28, or CD40L
expression within such subsets were observed by FACS analysis (data not
shown). Inflammatory arthritis is most likely Th1 mediated (38, 39). We therefore extended these studies to investigate effects
on Th1 and Th2 lymphocyte function. PHA-induced IFN- production in
vitro was suppressed in a dose-dependent fashion by day 29 (Fig. 3, a and b), but
reversed following completion of rhIL-10 administration. In contrast to
placebo recipients, there was a trend toward decreased IL-2 production
in IL-10 recipients. No significant effect on PHA-induced IL-4 (not
shown) or IL-5 production was observed, suggesting that the effects of
rhIL-10 were mediated by directly suppressing Th1 cell activity, rather
than by promoting Th2 cell cytokine production (Fig. 3c).
FACS analyses for mitogen-induced intracellular cytokine expression
were also performed. No consistent effect on intracellular IFN-,
IL-4, IL-5, or IL-10 expression was evident (Table II). Moreover, the frequency of
CD4+ T cells in purified PBMC that expressed
CCR5+, a marker of Th1 phenotype
(40), was not altered through therapy. Together these data
suggest that rhIL-10 mediated direct effects on the capability to
synthesize cytokine, rather than modulation of the absolute frequency
of circulating cells capable of Th1-type function.
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and IL-1 ex vivo. As
with IL-12, however, no consistent suppression of LPS-induced IL-18
generation in whole blood cultures, nor of total serum levels, was
evident in either cohort (data not shown). Effects on B cell function
Given the B cell stimulatory effects of IL-10, it was important to monitor effects on B cell activation. No alteration in the distribution or quantification of Ig subsets or isotypes was observed, nor did titers of autoantibodies (antinuclear Ab, rheumatoid factor) change with therapy. Moreover, neither numbers of circulating B lymphocytes (by FACS analysis), nor CD20+ cell infiltration in synovial or skin tissues (by immunohistochemistry) was increased (data not shown).
Modification of tissue inflammatory lesions
To determine whether these functional effects on circulating monocytes and lymphocytes were reflected by changes within inflammatory lesions, synovial membrane and skin biopsies were obtained before (day 1) and after (day 29) rhIL-10 administration.
Synovial membrane
Ten paired synovial biopsies were evaluable (four from placebo
cohort; three each in 5 and 10 µg/kg cohorts). Tissues were not
evaluated if biopsies were unavailable at both time points, if only
fibrous tissue was obtained, or if less than 6 representative hpf per
section were present. Significant reduction in the synovial
CD3+ cell population was detected in rhIL-10
compared with placebo recipients. This most likely reflected reduction
in CD4+ T subsets, since
CD8+ expression was unchanged (Fig. 4, a and b). Direct
CD4+ T cell enumeration was not possible due to
coincident macrophage CD4 expression. Similarly,
CD68+ macrophage numbers in both the lining layer
and sublining interstitium were reduced in rhIL-10-treated patients
(Fig. 4, c and d). These changes could have
reflected altered activation status in circulating leukocytes, since
CD68 is a mature macrophage marker, or modified transendothelial
migration. We therefore investigated soluble plasma and tissue adhesion
molecule expression, reflecting endothelial activation. No significant
alteration in circulating soluble VCAM (baseline, 559 v 548
pg/ml, and day 29, 847 v 1617 pg/ml; placebo v 10 µg/kg cohort,
p < 0.05) or soluble ICAM-1 (baseline, 13 v 16
ng/ml, and day 29, 16 v 18 ng/ml; placebo v 10 µg/kg cohort,
p < 0.05) was observed in active or placebo
recipients. In contrast, soluble P-selectin levels in plasma were
significantly suppressed by rhIL-10 therapy in a dose-dependent manner
(Fig. 5a). This was reflected
at the tissue level since the proportion of
P-selectin+ vessels identified in parallel
sections by vWF expression was significantly reduced (Fig. 5b). Soluble E-selectin levels in plasma and endothelial
tissue E-selectin expression, however, were similar in rhIL-10 and
placebo groups (Fig. 5, a and c). Since
P-selectin may selectively recruit Th1 cells (42), this
represents a further mechanism whereby Th1 responses may be ameliorated
by rhIL-10.
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Lesional and perilesional biopsies obtained before, and on
completion of, rhIL-10 administration were available from 14 patients.
In contrast to observations in synovial membrane, no consistent trends
in inflammatory cell subset infiltration, nor in adhesion molecule
expression were observed (data not shown). This was as expected since,
by study protocol, these biopsies were obtained from tissue sites that
remained clinically inflamed. Nevertheless, significant reduction in
the area of epidermal ki67, but not cytokeratin expression, was
observed in lesional, but not perilesional skin (Fig. 6, a and b),
suggesting effects on keratinocyte proliferation even in established
lesions. Although these data suggest differential effects of rhIL-10 in
discrete tissues, the small sample size and the inherent sampling bias
in skin noted before require cautious interpretation.
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A critical role for angiogenesis in inflammatory synovitis has
recently been recognized (43). In addition to synovial
biopsy, we performed MRI of the most inflamed, accessible joint in the
10 µg/kg rhIL-10 or matched placebo cohorts to evaluate synovial
enhancement. Improvement in MRI appearances was observed in rhIL-10,
but not in placebo recipients (Table III). Moreover, all rhIL-10-treated MRI
responders exhibited >20% swollen joint count (SJC) improvement.
Since early gadolinium uptake most likely reflects vascular flow, we
sought evidence for modulation of angiogenesis by rhIL-10. Expression
of the neovascular endothelial marker,
v3 integrin was
significantly down-regulated in vWF+ blood
vessels in both 5 and 10 µg/kg cohorts (Figs. 5
d,
6c, and 7). MMP production is
also implicated in angiogenesis. Moreover, serum MMP3 levels are
modified by anti-TNF- therapy, suggesting a direct link between
proinflammatory cytokine production, tissue remodeling, and erosion
(44). Unlike placebo, administration of rhIL-10 reduced
MMP3 levels and the ratio of MMP3/tissue inhibitors of MMPs
(p = 0.015 and p = 0.03,
respectively; Fig. 2c), suggesting that IL-10 may have
disease-modifying properties together with its antiinflammatory
effect.
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rhIL-10 administration was well tolerated, with no serious
clinical adverse effects observed. As predicted by previous studies,
hemoglobin concentrations and platelet counts were significantly
reduced in both 5 and 10 µg/kg cohorts, but did not reach levels
associated with serious clinical consequence and did not necessitate
study withdrawal. Although the present study was not adequately powered
to examine efficacy, IL-10 administration induced significant
improvement in the median PASI and in the number of 35% PASI
responders (Table IV; Fig. 6d;
p < 0.02). In contrast, IL-10 was not different from
placebo in inducing clinical improvement in articular measures of
disease activity (ACR20; Table IV). Since core criteria sets designed
for RA may not be applicable to PsA, we also analyzed individual
disease activity parameters, including tender joint count, SJC, and
health assessment questionnaire, but found no consistent changes
associated with rhIL-10 administration. Of interest, we found no
significant correlation between clinical and immunological
responders.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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IL-10 clearly modified immune responsiveness in vivo in PsA patients.
Mitogen-induced release of Th1 cytokines was reduced in peripheral
blood cultures. In contrast, intracellular expression of IL-4, IL-5,
IL-10, or IFN- was not altered. This suggests a quantitative effect
on T cell cytokine production, rather than modulation of memory T cell
differentiation by rhIL-10 administration. Similar T cell
hyporesponsiveness has been reported in SCID patients transplanted with
HLA-mismatched stem cells, who exhibit high levels of endogenous IL-10
expression (45). Although an alternate mechanism of action
of IL-10 could be the generation of T regulatory 1 cells,
CD4+ T cells characterized by high levels of
IL-10 expression (13), we did not, however, detect
increased numbers of IL-10-producing CD4 cells by intracellular
cytokine analysis. We did not consistently detect enhanced Th2-type
responses, in contrast to a previous study in which blood Th2 cell
frequency was increased after local IL-10 administration to psoriatic
patients (23). The reasons for this discrepancy are
currently unclear. The present study therefore establishes that T cells
can be functionally modified even in the context of ongoing autoimmune
activation. Th1 responses are implicated in psoriatic pathology and
with synovial inflammation (19, 22, 38, 39), suggesting
that these effects are of likely significance. An important proviso
lies in the lack of available data for tissue T cell responses. In some
circumstances, IL-10 can promote IFN- production by
CD8+ CTL in vitro (46). Since CD8 T
cells have been implicated in PsA synovitis, it is possible that the
effect of rhIL-10 administration upon synovial CD8 T cells differed
from that on peripheral blood T cells in which CD4 cell responses may
predominate.
rhIL-10 induced suppression of LPS-inducible monokine release, together with dose-dependent induction of TNFRII levels in serum. This provides compelling evidence for significant functional impairment of monocyte effector responses by rhIL-10, even in the context of ongoing autoimmune stimulation. Unlike previous studies, we did not see major effects on blood monocyte MHC class II expression, suggesting that this effect in circulating monocytes may not be a dominant feature during prolonged, systemic IL-10 therapy. No effect was evident by FACS on circulating costimulatory molecule expression (CD80 and CD86) by CD14 cells. However, IL-10 modifies skin-derived dendritic cell function in vitro (47), and such an effect for IL-10 therapy cannot be excluded.
An important element of the present study was the
comparison of tissue responses following rhIL-10 administration.
Reduced synovial infiltration by CD3 T cells and CD68 macrophages was
evident in rhIL-10 compared with placebo recipients. A likely
explanation for these effects was a direct effect on endothelial cell
activation. Both circulating soluble and tissue P-selectin levels were
reduced, providing a further potential mechanism for Th1 amelioration
since P-selectin glycoprotein ligand-1 is a putative Th1 adhesin
(48). No effect on E-selectin was observed, consistent
with previous in vitro data (49). Suppression of the
neovascular integrin marker
v3 was also evident
in skin and synovium. These changes correlated with clinical response
and improvement on MRI in the biopsied joint. Although interpreted on
small numbers of patients, these data suggest that it is possible to
modify endothelial activation and neovascularization by IL-10 therapy
in vivo, as previously demonstrated in vitro in tumor models
(50). Indeed, systemic administration may be optimal to
achieve functionally relevant bioavailability in the vasculature. Given
the key role for angiogenesis in inflammatory arthritis and psoriasis,
this is most likely an important observation. These data further
suggest that the combination of MRI and tissue biopsy deserves
validation in assessing responses to biological agents in inflammatory
arthritis.
Suppressed ki67 expression in psoriatic lesions suggested some early effect on keratinocyte proliferation was manifest even in clinically established cutaneous lesions. However, most inflammatory parameters in skin were unchanged when compared with placebo. The reason for this discrepancy with synovial tissue is presently unclear. However, since by definition we biopsied ongoing inflammatory skin lesions, the lack of significant histological evidence of resolution was predictable.
IL-10 has previously been shown to improve psoriasis in open-label, uncontrolled studies (23, 51). None of these reports included PsA patients. The primary outcome of this study was therefore to establish the safety and tolerability of IL-10 in PsA. Although it was not powered to address efficacy, improvement in the PASI was detected. We believe this report is the first demonstration of clinical efficacy in psoriasis using a placebo-controlled study design. With inclusion of placebo comparison, the magnitude of cutaneous response was modest and less than that anticipated from previous studies. However, unlike previous studies, patients were recruited for this study on the basis of articular rather than cutaneous disease activity. Nevertheless, it is of interest that administration of IL-10 in the psoriatic skin/SCID transplant model does not ameliorate clinical or histological inflammatory scores (52). Further placebo-controlled studies are therefore required to properly evaluate and quantify the therapeutic potential of IL-10 in cutaneous disease.
The apparent difference in cutaneous and articular responses is intriguing and could reflect several factors. Thus, available clinical assessment tools may not operate well in PsA. The ACR20 is validated in RA and may not adequately measure PsA responses. PsA is characterized by a limited acute phase response in comparison with RA. Moreover, IL-10 may mediate direct effects on acute phase reactants independent of effects on disease activity. However, even when we examined 50% improvement in SJC a potential surrogate, we detected similar response rates in active and placebo recipients. High placebo response rates in articular disease are well recognized with parenteral administration protocols, but are usually limited to the first 2 mo of treatment. Longer-term, appropriately powered studies will be required to clarify potential efficacy of IL-10 in articular disease. It is also possible that IL-10 administration is elucidating differences in the primary disease processes in skin and articular structures. Detailed comparative studies will be required to address this possibility, particularly with respect to the functional contribution of CD8 T cells, as noted above. However, most currently available data indicate that skin and synovial lesions contain similar cytokine expression patterns, particularly the paucity of IL-10, and share T cell clonal expansions (21, 27).
That immunological responses did not correlate directly with clinical responses illustrates the requirement for further study of those immunological parameters that best reflect relevant autoimmune disease processes ex vivo. Moreover, this study clarifies the importance of a placebo control, even for measurement of immunological activities, since trends demonstrated in smaller, noncontrolled studies have not been confirmed. It is reassuring that peripheral blood and endothelium, tissues most likely to be exposed to suppressive concentrations of IL-10, exhibited consistent functional changes on subsequent analysis. In summary, the present study clearly demonstrates that significant immune modulation can be safely achieved in PsA by administration of IL-10, and as such, it represents a valuable contribution to understanding the effects of IL-10 in vivo in an autoimmune/autoinflammatory disease context.
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Acknowledgments |
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Footnotes |
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2 I.B.M. and G.B.M. contributed equally to the present study.
3 Address correspondence and reprint requests to Dr. Ian B. McInnes at the current address: Center for Rheumatic Diseases, University of Glasgow, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow, G31 2ER, U.K. E-mail address: i.b.mcinnes{at}clinmed.gla.ac.uk
4 Abbreviations used in this paper: MMP, matrix metalloproteinase; hpf, high power field; MRI, magnetic resonance imaging; PASI, psoriasis area and severity index; PsA, psoriatic arthritis; RA, rheumatoid arthritis; rhIL-10, human rIL-10; vWF, von Willebrand factor; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; SJC, swollen joint count.
Received for publication February 6, 2001. Accepted for publication July 12, 2001.
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E Kruithof, D Baeten, F Van den Bosch, H Mielants, E M Veys, and F De Keyser Histological evidence that infliximab treatment leads to downregulation of inflammation and tissue remodelling of the synovial membrane in spondyloarthropathy Ann Rheum Dis, April 1, 2005; 64(4): 529 - 536. [Abstract] [Full Text] [PDF]
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N Dalbeth, S Yeoman, J L Dockerty, J Highton, E Robinson, P L Tan, D Herman, and F M McQueen A randomised placebo controlled trial of delipidated, deglycolipidated Mycobacterium vaccae as immunotherapy for psoriatic arthritis Ann Rheum Dis, June 1, 2004; 63(6): 718 - 722. [Abstract] [Full Text]
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,
IL-10 (10 µg/kg), n = 8; *,
p < 0.007; **, p < 0.05.
, 10 µg/kg 
, placebo; •, IL-10. – – – –, E-selectin; 
,
placebo; 
