Serum level TNF-alpha in patients with rheumatoid arthritis

The aim of this study is to evaluate serum levels of tumor necrosis factor-alpha (TNF-α) in rheumatoid arthritis patients and to assess the correlations of this cytokine with clinical and laboratory parameters.

SERUM LEVEL TNF-ALPHA IN PATIENTS WITH RHEUMATOID ARTHRITIS

Hoang Trung Dung*; Doan Van De**; Vien Van Doan*

SUMMARY

Objectives : To evaluate serum levels of tumor necrosis factor-alpha (TNF-α) in rheumatoid

arthritis patients and to assess the correlations of this cytokine with clinical and laboratory parameters. Subjects and methods: 122 patients with rheumatoid arthritis and 51 healthy

volunteers were enrolled in the study Disease activity was determined by disease activity score (DAS28) in patients with rheumatoid arthritis The serum levels of TNF-α cytokine was measured by chemiluminescent immune assay Results: We found that rheumatoid arthritis patients had

significantly higher levels of serum TNF-α (p < 0.01) as compared to healthy controls. Serum

TNF-α showed no significant correlations with mesurements of disease activity Conclusions: This study showed that patients with rheumatoid arthritis had a significantly higher TNF-α cytokine than that of healthy controls, and serum TNF-α cytokine was not associated with disease activity mesurements

* Keywords: Rheumatoid arthritis; TNF-α; Biomarkers

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic

inflammatory disorder that is characterised

by polyarthritis with often progressive joint

damage and disability, immunological

abnormalities, systemic inflammation,

increased co-morbidity, and premature

mortality [1] It affects 1% of the adult

population worldwide and also occurs

among one in a thousand children as

juvenile RA RA is much more common in

women and affects women 2 - 3 times

more frequently than men The aetiology

of RA is not known, but it is classified as

one of the autoimmune diseases. It is

associated with reduced life expectancy

and a major cause of chronic disability

and handicap, and conditions become

more dangerous with time Many studies have shown that advance therapy including the use of early, aggressive therapy, and the introduction of anti-cytokines agent have improved patient’s quality of life, eased clinical symptoms, retarded the progression

of joint destruction, and delayed disability Cytokine networks play a fundamental role in the processes that cause inflammation, articular destruction of RA [2] TNF-α is one of the pivotal pro-inflammatory cytokines responsible for inflammation and joint destruction in RA TNF-α is readily detected

in both synovial fluid and serum of patients with RA TNF-α is a key cytokine in the pathogenesis of RA that involved in chronic synovial inflammation andarticular destruction

* Bachmai Hospital

** 103 Military Hospital

Corresponding author: Hoang Trung Dung (dungbsbm@gmail.com)

Date received: 15/05/2018

Date accepted: 20/06/2018

TNF-α induces the production of other

proinflammatory cytokines, including IL-1

and IL-6 It also induces the production

and release of chemokines, hepcidine,

acute phase response as well as endothelial

cell activation, angiogenesis, activation of

chondrocyte of metalloproteinase production,

osteoclast activation [2], thus it may be

related to disease activity of RA

Several disease activity indices based

on different clinical, laboratory, and physical

measures have been introduced Most of

these, including the Disease Activity Score

(DAS), the modified DAS in 28 joints

(DAS28), rely on either quantitative joint

counts, patient-reported outcomes or both,

and erythrocyte sedimentation rate (ESR)

and serum CRP, those have some limitations

and can be influenced by aging, sex and

conditions other than RA (eg., osteoarthritis,

fibromyalgia, anemia) [3, 4]

The aim of this study was: To evaluate

serum levels of TNF-α in RA patients and

to assess the correlations of this cytokine

SUBJECTS AND METHODS

1 Subjects

at Bachmai Hospital between October 2014

and April 2018

122 patients (103 women and 19 men)

with the diagnosis of RA fulfilled the

ACR/EULAR 2010 RA classification

criteria [1] Patients with concomitant

other rheumatic disease, severe infection,

chronic autoimmune disease, and/or taking

bio-DMARDs which may effect laboratory

and cytokine profile were excluded from

the study

* Healthy subject population:

Fifty one sex-matched healthy controls (43 women and 8 men) were included in the study

2 Methods

* Clinical assessment:

Disease activity was assessed by the 28-joint disease activity score C-reactive protein (DAS28CRP) [5] in RA patients Based on the DAS28CRP, the patients were subdivided into 2 subgroups: low and moderate group (DAS28 ≤ 5.1), and high group (DAS28 > 5.1) Patient global assessment of disease activity and provides global assessment of disease activity were evaluated using a 10 cm horizontal

visual analog scale (VAS) Erythrocyte

sedimentation rate (ESR) and CRP were recorded

* Laboratory analysis:

Blood samples of patients and controls were collected and put in sterile plain tubes and stored frozen at -80oC until analysis Serum TNF-α was assayed by chemiluminescent immune assay (CLIA) The levels of cytokines were recorded as

a pg/mL

* Statistical analysis:

All statistical analyses were performed using the statistical package for the social sciences (SPSS), version 18.0 for Windows (SPSS, Chicago, IL, USA) Continuous variables are presented as the mean ± standard deviation or median The normality

of the distribution for all variables was assessed by the 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 To assess the

correlations between variables, Sperman’s

rank or Pearson’s correlation analysis

were used according to data distribution Values of p < 0.05 were considered

statistically significant

RESULTS

1 Patients and demographic, clinical characteristics

Mean DAS28 CRP ± SD

(Median; min-max)

5.77 ± 0.94;

6.02; 2.85 - 7.86

DAS28 CRP

(Abbreviations: ESR: Erythrocyte sedimentation rate; DAS28 CRP: Disease activity score c-reactive protein)

The mean age of the 122 patients with RA was 48.9 ± 11.3 years and the patient group was comprised of 19 males and 103 females Patients and controls did not significantly differ in age or sex The mean value of morning stiffness was 61.48 ± 27.64 min The mean DAS28 CRP was 5.77 ± 0.94 (range 2.85 - 7.86) Thirty one (25.4%)

and ninety one (74.6%) patients had low-moderate and high DAS28 CRP, respectively

2 Comparison of laboratory parameters among patients and healthy subjects

Table 2: Mean values of laboratory variables in RA patients and controls

(Abbreviations: TNF: Tumour necrosis factor; p: Test Mann-Whiney was used Data

is expressed as mean ± standard deviation (SD))

We found that the mean level of TNF-α was highly, significantly increased (p < 0.01)

in RA cases (15.32 ± 7.37 mg/dL) compared to the healthy controls (8.84 ± 2.17 pg/mL) There were highly significant increases in CRP (2.56 ± 2.81 vs 0.12 ± 0.12 mg/dL) levels in patients with RA compared to the control group (p < 0.001)

3 Correlation between serum TNF-α and clinical, laboratory variables in RA patients group

Serum TNF-α levels (pg/mL)

p

DAS28 CRP

> 0,05

Table 4: The correlation of serum TNF-α levels in RA patients with measurements of

disease activity

Serum TNF-α

(Abbreviations: TJC: Tender joint count; SJC: Swollen joint count: MS: Morning stiffness, r: Spearman’s correlation coefficient)

There were no differences according to joint tender count 28, joint swollen count 28, morning stiffness, C reactive protein and erythrocyte sedimentation rate

Serum TNF-α

There were not associations between the serum TNF-α levels of RA patients with

measurements of disease activity

DISCUSSION

In the present study, we evaluated

serum levels of TNF-α cytokines in patients

with established RA, and associations of

these cytokines with clinical and laboratory

parameters

TNF-α is one of the key cytokines in

the pathogenesis of RA, and TNF inhibitors

are major biologics in the treatment of RA

In our study, we found significant increased

levels of TNF-α in RA patients as compared

to the healthy controls (table 2) A study

by do Prado A.D et al (2016) observed serum TNF-α was increased in RA patients compared to healthy controls (p < 0.001) [6] However, Kokkonen H et al (2010) found serum TNF-α had no differences between

RA patients and healthy controls [7] This condition may be caused by RA patients who were first diagnosed and not treated, TNF-α levels were high These findings suggest that TNF-α is important mediators

of inflammation in RA and play a pivotal role in the development and progression

of RA

TNF-α is a key cytokine in the

pathogenesis of RA that involved in chronic

synovial inflammation and articular

destruction, thus it may influence disease

activity of RA patients We assessed the

change of serum TNF-α according to

measurements of disease activity including

TJC28, SJC28, MS, CRP, ESR, DAS28

CRP, DAS28 ESR However, we did not

find differences based on these parameters

Consistantly with the present study, Prado

A.D et al (2016) observed serum TNF-α

had no associations with joint tender

count 28, joint swollen count 28, DAS28

CRP, DAS28 ESR [6] Keiko Shimamoto

et al (2013) found serum TNF-α was not

related to DAS28 CRP and DS28 ESR

Our study has some limitations The

sample size of patients was relatively

small, and the patients were on drug

treatment including DMARDs Treatment

regimes might influence on the serum

expression of cytokines In fact, our study

had a cross-sectional design, and cytokines

profile could not evaluate compared to

patients with early treatment naive RA

CONCLUSION

Our study demonstrated a significantly

higher of serum TNF-α in RA patients

comparing with healthy controls However,

we did not find any associations between

serum TNF-α levels and measurements

of disease activity in RA patients

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