|Year : 2017 | Volume
| Issue : 3 | Page : 952-957
Role of interleukin-33 in rheumatoid arthritis patients from Menoufia University Hospitals
Ahmed A Salama1, Ahmed B Mahmoud1, Dina R Al-Sharaki2, Alaa F Gomah3
1 Microbiology and Immunology Department, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Physical Medicine and Rehabilitation Department, Faculty of Medicine, Menoufia University, Menoufia, Egypt
3 Microbiology and Immunology Department, Shebien El Kom Teaching Hospital, Menoufia, Egypt
|Date of Submission||18-Jul-2016|
|Date of Acceptance||09-Nov-2016|
|Date of Web Publication||15-Nov-2017|
Alaa F Gomah
Microbiology and Immunology Department, Shebien El Kom Teaching Hospital, Menoufia, 32511
Source of Support: None, Conflict of Interest: None
The objective of this study was to detect the level of interleukin-33 (IL-33) in patients with rheumatoid arthritis (RA) and to explore the relationship between the level of IL-33 in the serum with the disease activity and functional performance.
Cytokines are important mediators of immune functions in humans and animals. IL-33, a newly found IL-1 family cytokine, is involved in joint inflammation in RA. Therefore, we aimed to investigate the immunopathological roles of IL-33 in serum RA patients.
Patients and methods
This study was conducted on a total of 80 individuals: 60 of them were RA patients (55 female and five male) and 20 healthy controls (17 female and three male). All RA patients and controls were evaluated by measuring complete blood count, erythrocyte sedimentation rate, C-reactive protein (CRP), anticitrullinated proteins (anti-CCP), and rheumatoid factor (RF). IL-33 level was measured in the serum of both RA patient group and control group.
The mean erythrocyte sedimentation rate, serum CRP, anti-CCP antibodies, and RF in addition to the detection percentages of serum IL-33 were significantly higher in the RA group than in the control group. In the RA group, serum IL-33 showed significantly positive correlations with DAS-28, visual analogue scale, RF, CRP, and anti-CCP antibodies.
IL-33 has an important proinflammatory role in the pathogenesis of RA. Considering their correlation with disease activity, they may become potential therapeutic targets for RA.
Keywords: DAS-28, inteleukin-33, rheumatoid arthritis
|How to cite this article:|
Salama AA, Mahmoud AB, Al-Sharaki DR, Gomah AF. Role of interleukin-33 in rheumatoid arthritis patients from Menoufia University Hospitals. Menoufia Med J 2017;30:952-7
|How to cite this URL:|
Salama AA, Mahmoud AB, Al-Sharaki DR, Gomah AF. Role of interleukin-33 in rheumatoid arthritis patients from Menoufia University Hospitals. Menoufia Med J [serial online] 2017 [cited 2019 Nov 21];30:952-7. Available from: http://www.mmj.eg.net/text.asp?2017/30/3/952/218272
| Introduction|| |
Rheumatoid arthritis (RA) is a systemic, chronic, autoimmune, and inflammatory disease that may affect many tissues and organs, but principally attacks flexible (synovial) joints . It is an autoimmune disease without precisely known pathogenesis. Genetic factors contribute to the development of RA . Prevalence of RA is up to three times higher among women. It is observed with increasing incidence after the age of 25 years, with greater involvement of populations between 35 and 55 years . RA is characterized by synovial inflammation and hyperplasia (swelling), autoantibody production [rheumatoid factor (RF) and anticitrullinated protein (anti-CCP) antibody], cartilage and bone destruction (deformity), and systemic features, including cardiovascular, pulmonary, psychological, and skeletal disorders . The most common clinical symptoms include symmetrical arthralgia, mainly present in the hands and feet, stiffness, joint damage, and loss of physical function . It predominantly affects the joints of the wrist, metacarpophalangeal, and proximal interphalangeal joints of upper limbs . The treatment of patients diagnosed with RA should be started as soon as possible, aiming to reduce the inflammatory activity of the disease and even to obtain remission of symptoms . Interleukin-33 (IL-33) is a novel member of the IL-1 cytokine family. It is initially reported as a nuclear factor presenting in endothelial cells and is now recognized as a cytokine characterized by promoting Th2 response. IL-33 has been reported to play an unfavorable role in arthritis. Serum and synovial levels of IL-33 were increased in patients with RA. Moreover, IL-33 has been found to induce neutrophil migration and infiltration and increase IL-17 and tumor necrosis factor-α production, which exacerbates arthritis .
The aim of the study was to detect the level of IL-33 in patients with RA and explore the relationship between the level of IL-33 in the serum of RA patients with the disease activity and functional performance.
| Patients and Methods|| |
The study was conducted as follows:
- A total of 60 patients suffering from RA, 55 female and five male, were included in the study. Their age ranged from 32 to 56 years with a mean of 44.52 ± 12.24 years, and the duration of their disease ranged from 1 to 20 years, with a mean of 6.21 ± 4.5 years (group 1). Patients were selected from outpatient clinics of Physical Medicine, Rheumatology and Rehabilitation Department of Menoufia University Hospitals
- A total of 20 apparently healthy controls, 17 female and three male, were also included. Their age ranged between 30 and 55 with a mean of 43 ± 9.61 years (group 2).
Patients included in this study were chosen according to these criteria:
The inclusion criteria were as follows:
- Definitely diagnosed RA according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA (ACR/EULAR) 
- Patients must be under RA treatment for at least 3 months.
The exclusion criteria were as follows:
- Patients with general illness that interferes with functional performance (heart disease, renal disease, bronchial asthma, diabetes mellitus, known malignancy)
- Patients with locomotor disability other than RA (stroke, limb amputation, polyneuropathy, fracture).
All patients were subjected to the following
- Patient consent
- Full history and general examination
- Rheumatological examination: Joints of the body were examined by inspection, palpation, and movement examination for swellings or tenderness
- Disease activity evaluation using the Disease Activity Score-28
- Pain severity evaluation using the visual analogue scale
- Functional performance evaluation according to Modified Health Assessment Questionnaire
- Laboratory investigations including complete blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), RF, and anti-CCP
- Estimation of serum level of IL-33 using Boster's human IL-33 ELISA kits (Boster Biological Technology Co. Ltd, Pleasanton, California, USA). Boster's human IL-33 ELISA kit was based on standard sandwich enzyme-linked immunosorbent assay technology. A monoclonal antibody from mouse specific for IL-33 was precoated onto a 96-well plate. Standards ( Escherichia More Details coli-S112-T270) and test samples are added to the wells; a biotinylated detection polyclonal antibody from goat specific for IL-33 is added subsequently, followed by washing with PBS or Tris-buffered saline buffer. Avidin–biotin–peroxidase complex was added and unbound conjugate was washed away with PBS or Tris-buffered saline buffer. Horseradish peroxidase (HRP) substrate 3,3', 5, 5'-tetramethylbenzidine (TMB) was used to visualize HRP enzymatic reaction. TMB was catalyzed by HRP to produce a blue color product that changed into yellow after adding acidic stop solution. The density of yellow is proportional to the human IL-33 amount of the sample captured in the plate.
The data were collected and tabulated and analyzed by SPSS, version 20; SPSS Inc., Chicago, Illinois, USA on an IBM-compatible computer. Data were expressed as percentage (%), mean, and SD. Student's t-test is a test used for comparison between groups having quantitative variables. Mann–Whitney test (nonparametric test) is a test of significance used for comparison between two groups not normally distributed having quantitative variables. Kruskal–Wallis test (nonparametric test) is a test of significance used for comparison between more than two groups not normally distributed having quantitative variables. χ2-Test was used to study the association between two qualitative variables. Spearman's correlation coefficient (r) (nonparametric test) is a test used to measure the association between two quantitative variables. Level of significance was set as P value less than 0.05. The receiver operating characteristic curve is a graphic representation of the relationship between sensitivity and specificity at different cutoff points for a diagnostic test.
| Results|| |
This study included 60 RA patients (55 female and five male). They were diagnosed according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA (ACR/EULAR), recruited from patients attending the outpatient clinics of Physical Medicine, Rheumatology and Rehabilitation Department of Menoufia University Hospitals. The patient characteristics are presented in [Table 1]. In all, 20 apparently healthy volunteers matched for age and sex with the patients were enrolled in this study.
IL-33 serum concentrations were higher in patients with RA when compared with healthy individuals. The mean serum level of IL-33 (pg/ml) in the studied group of patients was 185.1 ± 85.7 pg/ml, whereas in the control group the mean serum level of IL-33 was 53 ± 19.8 pg/ml, with a statistically highly significant difference between the two groups (P = 0.001), as shown in [Table 2] and [Figure 1]).
|Table 2: Comparison between mean levels of serum interleukin-33 (pg/ml) in patient and control groups|
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|Figure 1: Comparison between mean levels of serum interleukin-33 (IL-33) in patient and control groups.|
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In our study, serum concentration of IL-33 in RA patients was not affected by age or sex, as all had a P value more than 0.05, as shown in [Table 3].
|Table 3: Correlation between serum levels of interleukin- 33(pg/ml) and demographic data in the rheumatoid arthritis patient group|
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According to the clinical data of RA patients, there was a statistically significant difference between serum levels of IL-33 regarding visual analogue scale (P < 0.05) [Figure 2] and a statistically highly significant difference regarding DAS-28 (P = 0.001) [Figure 3]. On the other hand, there was no statistically significant difference between serum IL-33 levels according to the duration of disease and Modified Health Assessment Questionnaire (P > 0.05), as shown in [Table 4].
|Figure 2: Correlation between serum levels of interleukin-33 (IL-33) in pg/ml and visual analogue scale (VAS) in the rheumatoid arthritis (RA) patient group.|
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|Figure 3: Correlation between serum levels of interleukin-33 (IL-33) in pg/ml and DAS-28 in the rheumatoid arthritis (RA) patient group.|
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|Table 4: Correlation between serum levels of interleukin- 33(pg/ml) and clinical findings in the rheumatoid arthritis patient group|
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In our study, we showed the relationship between serum levels of IL-33 (pg/ml) among the studied group of cases and their laboratory parameters. There was a statistically significant difference between serum levels of IL-33 regarding white blood cell count, platelet count, and ESR (P < 0.05), and a highly significant difference regarding CRP titer, RF, and anti-CCP titers (P < 0.001). On the other hand, there was no statistically significant difference between serum levels of IL-33 in RA patients regarding hemoglobin %, as shown in [Table 5].
|Table 5: Correlation between serum levels of interleukin- 33(pg/ml) among the studied group of cases and laboratory parameters|
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Regarding the correlation between serum levels of IL-33 in RA patients and the activity of the disease, we found in this study that the mean value of serum levels of IL-33 in patients with low disease activity was 129.2 ± 29.5 pg/ml, the mean value of serum levels of IL-33 in patients with moderate disease activity was 165.1 ± 60.5 pg/ml, and the mean value of serum levels of IL-33 in patients with high disease activity was 259.7 ± 111 pg/ml. The serum IL-33 concentrations were higher in RA patients with high disease activity than RA patients with moderate and mild disease activity, with a statistically significant difference between them (P < 0.05), as shown in [Table 6] and [Figure 4].
|Table 6: Correlation between serum levels of interleukin-33 and DAS-28 in rheumatoid arthritis patients|
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|Figure 4: Correlation between serum levels of interleukin-33 (IL-33) and DAS-28 in rheumatoid arthritis (RA) patients.|
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| Discussion|| |
RA is a common autoimmune disease associated with progressive disability, systemic complications, early death, and high socioeconomic costs. RA is characterized by synovial inflammation and hyperplasia (swelling), autoantibody production (RF and anti-CCP antibody), cartilage and bone destruction (deformity), and systemic features, including cardiovascular, pulmonary, psychological, and skeletal disorders . A number of genetic and environmental factors contribute to disease onset and severity  In addition, a number of viral and bacterial pathogens, such as Epstein–Barr virus, parvovirus B19, hepatitis C virus, Proteus mirabilis, and Mycobacterium tuberculosis, may have a role in disease pathogenesis as well . The prevalence of systemic or extra-articular manifestations in patients with RA is ~8–12%. Cardiovascular disease is one of the major causes of increased mortality in patients with RA .
IL-33, a member of the IL-1 family, is a ligand for the orphan receptor ST2 (also known as IL-1RL1). When IL-33 binds to ST2, it enhances inflammatory cytokines via the activation of nuclear factor-jB and mitogen-activated protein kinases . IL-33 is involved in T-cell-mediated immune responses and works as a central regulator of human autoimmune diseases . IL-33 was detected at high levels in experimental inflammatory arthritis and in the early phase of human RA and was reported to exert profound proinflammatory effects in several experimental autoimmune models. Moreover, administration of IL-33 led to the development of severe inflammatory arthritis, suggesting that IL-33 may be therapeutically relevant in RA .
The aim of this study was to determine whether IL-33 could reflect RA disease activity, severity, and to analyze its relation with various RA disease parameters.
In this study, the mean level of IL-33 in serum in RA patients was 185.1 ± 85.7 pg/ml and was significantly higher than that of healthy controls (53 ± 19.8 pg/ml) (P < 0.05), and the cutoff value using receiver operating characteristic curve was 103.5 pg/ml with a positive predictive value of 98 and a sensitivity of 98. Serum IL-33 showed an excellent diagnostic performance. These findings coincided with those of Matsuyama et al. , Mu et al. , Hong et al. , Xiangyang et al. , Khalifa and Abdelfattah , Talabot-Ayer et al. , and Tang et al.. This indicated that IL-33 may be involved in the pathogenesis of RA. In addition, the differences in IL-33 levels between patients and healthy controls may suggest the possibility of using anti-IL-33 therapy to treat RA patients characterized by high levels of IL-33 .
In this study, there was a nonsignificant difference between serum levels of IL-33 in the patient group according their age and sex (P > 0.05). Hong et al.  compared the serum levels of IL-33 in younger RA patients (≤65 years) with older patients (>65 years) to ascertain the impact of age on IL-33 level. The mean value of serum IL-33 was not different between the two groups (P = 0.167). They concluded that the age factor did not seem to influence the level of circulating IL-33 in RA patients. Jahromi et al.  and Dwedar et al. reported that the assessment of serum IL-33 levels between subjects of different sex and age groups showed nonsignificant differences.
According to this study, there was no significant correlation between IL-33 concentrations and duration of RA disease. However, Dwedar et al.  found that IL-33 level showed a significant negative correlation with disease duration in years.
Our study demonstrated a positive significant correlation between serum IL-33 concentrations and DAS-28 score, and thus serum IL-33 concentrations were higher in RA patients with high disease activity than RA patients with moderate and mild disease activity, with a statistically significant difference between them (P < 0.05). This was in agreement with the study by Matsuyama et al. , who showed that serum IL-33 levels were significantly higher in RA patients, especially in the high disease activity group compared with the moderate or low activity group. The studies conducted by Khalifa and Abdelfattah  and Kageyama et al.  also reported that serum IL-33 was related to RA disease activity. In contrast, Dwedar et al. and Xiangyang et al.  showed that there was no correlation between serum IL-33 and DAS-28. Further research should be performed to ascertain the utility of IL-33 as a biomarker for assessing disease activity in patients with RA .
In this study, there was a nonsignificant correlation between serum levels of IL-33 and hemoglobin concentration. This was in accordance with the studies conducted by Kageyama et al.  and Duan et al. , who reported a nonsignificant correlation between serum levels of IL-33 and hemoglobin in RA patients.
In this study, we found a positive correlation between serum level of IL-33 and white blood cell count in RA patient group. Kageyama et al.  and Khalifa and Abdelfattah  also reported this positive relationship.
In our study, we found that there was a statistically significant positive correlation between serum IL-33 levels and ESR (P < 0.05). This is parallel to the studies of Kageyama et al. , who found that serum IL-33 concentrations positively correlate with ESR in their study.
In our study, we found that there was a high statistically significant positive correlation between serum IL-33 levels and CRP (P < 0.001). This was in agreement with the result of Kageyama et al.  and Al-Rubaei et al. , who found a significant positive correlation between IL-33 and CRP in the patient group. The positive correlation between the level of IL-33 and acute-phase reactant levels in RA patients may indicate an intimate relationship between IL-33 and inflammatory status of RA. The measurement of serum IL-33 levels in RA patients may become a useful control marker for RA treatment . In contrast, Mu et al. , Xiangyang et al. , and Li et al.  reported that no correlation was found between serum IL-33 concentration and the markers for inflammation (e.g., the acute-phase inflammation reactant in RA).
In this study, we showed that there was a statistically positive correlation between serum IL-33 levels and prevalence of RF (r = 0.790, P < 0.001) in RA patients. We showed also a positive correlation between serum level of IL-33 and anti-CCP antibody titers (r = 0.646, P < 0.001) in RA patients. Mu et al.  showed that the levels of serum IL-33 were positively correlated to production of IgM and RA-related autoantibodies including RF and anti-CCP antibodies. Xiangyang et al.  and Li et al.  also reported in their studies the positive correlation between serum levels of IL-33 and production of RF, and they found significantly higher levels of IL-33 in the CCP-positive group. Khalifa and Abdelfattah  found a significant positive correlation between serum level of IL-33 and RF in the RA group, whereas our results were not supported by Tang and colleagues, who found significant correlations regarding disease activity and RF with synovial fluid IL-33 only.
One of our study limitations is lack of evaluation of synovial fluid for IL-33. Tang et al.  conducted a study on 120 RA and 30 osteoarthritis patients, in which serum and synovial fluid were obtained and the levels of IL-33 and sST2 were measured by ELISA. Correlations were analyzed between the clinical features and IL-33 levels in synovial fluid (SF) and serum of patients with RA. Compared with the serum IL-33, SF IL-33 level in RA had more correlations with clinical features including disease activity features (ESR, DAS-28 score) and autoantibodies (RF IgM, RF IgG, IgA, IgG, and IgM).
| Conclusion|| |
Serum IL-33 was elevated in patients with RA, and was associated with high disease activity, production of RF, anti-CCP antibodies, and levels of acute-phase reactants (ESR, CRP). This suggested possible therapeutic significance of IL-33 in RA.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]