To investigate serum level of interleukin-17 in rheumatoid arthritis patients and to assess the relationship of this cytokine with serum levels of IL-6 and tumor necrosis factor α. Subjects and methods: 82 patients with rheumatoid arthritis and 30 healthy volunteers were enrolled in the study. Disease activity was determined by disease activity score (DAS28) in patients with rheumatoid arthritis.
Trang 1SERUM LEVEL OF INTERLEUKIN-17 AND ITS RELATION TO INTERLEUKIN-6 AND TUMOR NECROSIS FACTOR ALPHA
LEVEL IN PATIENTS WITH RHEUMATOID ARTHRITIS
Nguyen Huy Thong 1 ; Nguyen Dang Dung 2 ; Quyen Dang Tuyen 1
SUMMARY
Objectives: To investigate serum level of interleukin-17 in rheumatoid arthritis patients and to assess the relationship of this cytokine with serum levels of IL-6 and tumor necrosis factor α Subjects and methods: 82 patients with rheumatoid arthritis and 30 healthy volunteers were
enrolled in the study Disease activity was determined by disease activity score (DAS28) in patients with rheumatoid arthritis Serum levels of IL-6, IL-17 and TNF-α were measured by fluorescence covalent microbead immunosorbent assay Results: Serum level of IL-17 in rheumatoid arthritis patients and controls were 0.59 ± 0.92 and 0.62 ± 0.94 pg/mL, respectively There was no difference in serum levels of IL-17 in RA patients compared to that in controls (p > 0.05) Serum IL-17 level, however, seemed to be correlated with changes in serum levels of IL-6 and TNF-α in rheumatoid arthritis patients: in patients with elevated serum levels of IL-17, the IL-6 and TNF-α were higher compared to those in patients with normal serum level of IL-17
Conclusions: Serum level of IL-17 in patients with rheumatoid arthritis did not differ from that in healthy people Higher serum level of IL-17 correlated with higher serum levels of of IL-6 and TNF-α
* Keywords: Rheumatoid arthritis; IL-6; IL-17; TNF-α
INTRODUCTION
Rheumatoid arthritis (RA) is a chronic
inflammatory disease characterized by joint
swelling, joint tenderness, and destruction
of synovium, leading to severe disability
and premature mortality of patients [1]
Cytokine networks play a fundamental
role in the processes that cause
inflammation, articular destruction of RA
[2] IL-17 possesses properties of a
pro-inflammatory cytokine, and plays very
important roles in pathogenesis of RA [3]
IL-17 is a cytokine that stimulates the
production of a variety of inflammatory
mediators, and plays a leading role in regulating the relationship between pro-inflammatory cytokines In this role, IL-17 activates not only B cells to produce antibodies, but also macrophages, synovial fibroblasts, chondrocytes to secret cytokines, such as IL-1, IL-6, TNF-α, and matrix metalloproteinase (MMPs) [4, 5].That is the reason why serum IL-17 may be related
to serum IL-6 and TNF-α in RA patients
Thus, the aim of this study was: To
evaluate serum levels of IL-17 and its relation serum IL-6 and TNF-α levels in
RA patients
1 103 Military Hospital
2 Vietnam Military Medical University
Corresponding author: Nguyen Dang Dung (dzungmd@yahoo.com)
Date received: 26/06/2019
Date accepted: 06/08/2019
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SUBJECTS AND METHODS
1 Subjects
* Patients:
This study was carried out at Department
of Rheumatology and Endocrinology of
103 Military Hospital between May 2012
and June 2015
Eighty two patients, 71 women and 11
men, with the diagnosis of RA fulfilled the
ACR/EULAR 2010 RA classification
criteria [1] Before entering study, 43 and
4 patients were taken glucocorticoids and
conventional synthetic disease-modifying
respectively Patients with other
concomitant rheumatic diseases, severe
infections, chronic autoimmune diseases,
and/or taking bio-DMARDs which may
influence laboratory and cytokine profile
were excluded from the study
* Healthy subject population: thirty
sex-matched healthy controls (mean age
41.60 ± 4.57; range, 35 - 50 years, 26
women and 4 men) were included in the
study
2 Methods
* Clinical assessment:
Disease activity was assessed by the
28-joint disease activity score C-reactive
protein (DAS28 CRP) [6] in RA patients
Patient global assessment of disease
activity and provider global assessment
of disease activity were evaluated
using Visual Analog Scale Formats for
assessment of disease activity [7] Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP) were also recorded
* Laboratory analysis:
Blood samples of patients and controls were collected and put in a sterile plain tube and stored frozen at -80oC until analysis We used commercially available human Fluorescence covalent microbead immunesorbent assay (FCMIA) kits for
IL-6, IL-17 and TNF-α (R&D systems MN, USA) The assay was performed according
to the instructions provided by the manufacturer Serum levels of cytokines were reported as pg/mL
The cut-off values of serum IL-6, IL-17 and TNF-α were determined by ROC (Receiver Operating Curve)
* Statistical analysis:
All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) for Windows, version 18.0 (SPSS, Chicago, IL, USA) Continuous variables are presented as mean ± standard deviation or median The normality of the distribution for all variables was assessed by Kolmogorov-Smirnov test Intergroup comparisons
were made using the student’s t-test for
normally distributed variables and
Mann-Whitney U test for non-parametric
variables Difference with p value being less than 0.05 was considered statistically significant
Trang 3RESULTS
1 Patients and demographic, clinical characteristics
Table 1: Demographic and clinical characteristics of RA patients and controls
RA group (n = 82)
Control group (n = 30)
Mean tender joint count ± SD (range 0 - 28) 14.13 ± 9.08; 13.00
7.16 ± 2.25
Mean provider global assessment of disease
5.65 ± 1.92
DAS28 CRP
Pre-study
treatment
(DAS28 (CRP) is missing in three patients)
(Anti-CCP: Anti-cyclic citrulinated peptide; CRP: C-reative protein; DAS28: Disease Activity Score; ESR: Erythrocyte Sedimentation Rate)
Patients and healthy people in the control group did not significantly differ in sex distribution The mean age of controls was considerably lower than that in RA patients The mean disease duration in RA patients was 4.29 ± 5.34 years The mean DAS28 CRP was 6.19 ± 1.36 (range, 2.81 - 8.50) The proportion of patients had low or moderate and high disease activity based on DAS28 CRP was 20.5% (17/83 patients)
and 79.5% (66/86 patients), respectively
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2 Changes in serum levels of IL-17, IL-6, TNF-α and relations between serum IL-17 and serum IL-6, TNF-α in RA patients
Table 2: The comparison of serum IL-6, IL-17 and TNF-α levels of patients and controls
Serum cytokines
IL-6
< 0.05*
IL-17
> 0.05
TNF-α
< 0.001*
(*: Test Mann - Whitney, IQR: Interquartile Range)
Statistics shows that the median of serum IL-6 of patients was considerably higher than that in controls (p < 0.05) There was no significant difference in the median of serum IL-17 levels between patients and controls The median of serum TNF-α of patients was significantly lower than that in controls (p < 0.001)
Chart 1: The distributions of RA according to serum IL-17 levels
The percentage of patients with elevated serum cytokine levels (elevated serum levels of 1, 2 or 3 cytokines) was 73.20%, among which the percentage of patients with elevated serum IL-17 (either single elevation of IL-17 level, or elevated IL-17 in combination with IL-6 and/or serum TNF-α) was 56.10%; meanwhile, only 17.10% of
RA patients had elevated IL-6 and/or TNF-α level
Trang 5Table 3: The comparison of serum IL-6 and serum TNF-α based on serum IL-17 groups
Serum IL-17
p
Serum IL-6 (pg/mL)
0.068*
Serum TNF-α (pg/mL)
< 0.05*
(*: Test Mann - Whitney; IQR: Interquartile Range)
Assessing the change of serum IL-6, TNF-α according to serum IL-17 groups of RA patients, the results showed that the median of serum TNF-α of patient group with elevated serum IL-17 was higher than that of healthy group (p < 0.05) The median serum IL-6 had an increased trend in patients with elevated serum IL-17 compared to healthy group (p = 0.068)
DISCUSSION
In the present study, serum levels of
IL-17 as well as IL-6 and TNF-α cytokine
were evaluated in patients with RA
Additionally, the relationships between
serum IL-17 and serum IL-6, TNF-α were
also assessed
Our results showed that there was no
significant difference in median value of
serum IL-17 level of the patients compared
to that of the controls (p = 0.879, by
Mann-Whitney test) (table 2) However,
the percentage of RA patients having
elevated serum IL-17 level was 56.10%,
which was higher than that of IL-6 and
TNF-α (chart 1)
In contrast, it was reported that in RA
patients, serum level of IL-17 was
significantly higher than that in healthy
people [8, 9, 10], as well as that of
patients with osteoarthritis [11] IL-17 level
was not only elevated in serum, but also
in synovial fluid of RA patients at early stage of the disease without treatment, and the level of IL-17 in synovial fluid was proportionally correlated with that in serum [9, 12]
The results of current study showed that serum IL-17 levels in RA patients were not elevated compared to that in healthy people This was probably because in RA patients at the clinical period of the disease, serum IL-17 level might be lower than that before the disease onset, which was in accordance with remarks by Kokkonen H et al (2010),
in which the authors found that median value of serum IL-17 levels of RA patients before disease onset was 28.7 pg/mL and then it decreased to 6.0 pg/mL during the illness period of the disease, which was lower than that in healthy people at the same age and gender distribution (being
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21.1 pg/mL) The difference in serum
IL-17 level of the RA patients and of the
controls was significant with p value being
6.1 x 10-5 [13]
Additionally, it was reported that the
production and secretion of most of Th1
cytokines (IL-1β, IL-2, IL-3, IL-6, TNF,
interferon-γ) and Th17 cytokines (IL-17,
GM-CSF) were down-regulated by
corticoids [14] In this study, 50.6% of RA
patients were treated by corticoids before
having serum cytokines testing (table 1),
and it might be one possible cause of the
low level of serum IL-17 we have observed
However, when analyzing data, the results
of this study indicated that there was no
significant difference between median
values of serum IL-17 levels of the RA
patients who underwent corticoid treatment
compared to that of treatment-nạve ones
Furthermore, in this study, the change
in serum IL-17 level seemed to influence
the change in serum IL-6 and TNF-α
levels The results of chart 1 and table 3
indicated that serum IL-17 levels of RA
patients were increased along with elevation
of serum IL-6 and TNF-α levels These
findings were in accordance with a report
by Miossec P (2007), in that IL-17 seemed
to play a central role in pathogenesis of
RA by stimulating synovial macrophages,
fibroblasts and dendritic cells to produce
and secrete pro-inflammatory cytokines,
including IL-6 and TNF-α [4], and in the
meantime, IL-17 was the "conductor" that
regulated the interaction between cytokines
[5]
Our study has some limitations The
sample size of patients was relatively
small, many patients were on medication
treatment, including glucocorticoids as
well as DMARDs, before enrolment in this research Treatment regimens might influence the serum levels of cytokines
On the other hand, this study was designed as a cross-sectional one, and cytokines profile was not evaluated in comparison with that in treatment-naive
RA patients Furthermore, patients of this study were mainly in an established period of RA disease
CONCLUSION
This study demonstrated that there was no difference in serum IL-17 between
RA patients and healthy people Serum IL-17 seemed to influence the changes in serum IL-6 and TNF-α in RA patients However, further follow-up research involving large samples are required to clarify the precise role of IL-17 in relationships with IL-6 and TNF-α in the development of RA disease
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