Serum Interleukin-34 in Psoriatic arthritis patients and its correlation with disease 1 activity, and subclinical atherosclerosis
Egyptian Rheumatology and Rehabilitation volume 50, Article number: 18 (2023)
Psoriatic arthritis (PsA) is a chronic multi-domains autoimmune inflammatory disorder. Patients with PsA have a significant prevalence of cardiovascular affection. Upregulated Interleukin-34 (IL-34) has been seen in many autoimmune disorders, and also in atherosclerotic plaques. The aim of this observational case–control study was to evaluate the serum levels of il-34 in PsA patients and correlate between its level and disease activity, and subclinical cardiovascular affection.
In this study, there were 70 PsA patients and 70 healthy volunteers, 43 patients were on Methotrexate, 6 on sulfasalazine, while 40 patients were on biological therapy either monotherapy or in combination with DMARDs. There were significant differences between PsA patients and controls in ESR, high sensitivity-CRP, total lipid profile, and IL-34 levels (p < 0.05) while there were no significant differences regarding Echo and ECG results. Also, we found that there was significant elevation in DAPSA score, hs-CRP, IL-34, and cIMT in the active patients when we compared them with inactive patients. IL-34 had significant positive correlations with DAPSA score, hs-CRP, and cIMT (r = 0.654, 0.579, and 0.658 respectively).
Serum interleukin-34 is an important marker in PsA as its levels were elevated in PsA patients and were correlated with disease activity and subclinical cardiovascular affection.
Patients with immune-mediated disorders like psoriasis, PsA, and rheumatoid arthritis have an increased risk of early mortality due to atherosclerotic vascular disease [3, 4]. Although it is well established that individuals with psoriasis or PsA, particularly those who also have metabolic syndrome, have significantly higher rates of cardiovascular (CV) risk factors, this does not entirely explain the higher rates of CV mortality and morbidity in these patients [5, 6].
High-resolution carotid ultrasonography is used to measure the intima and media thickness of the carotid arteries. Atherosclerosis in arterial beds has been linked to increased intima-media thickness (IMT) of the common carotid artery [7, 8].
In asymptomatic individuals, IMT behaves as a risk factor for myocardial infarction and stroke independent of known cardiovascular risk factors . Based on this, assessing carotid IMT with ultrasound techniques provides useful information on atherosclerosis in susceptible individuals in the early stages of the disease .
Interleukin-34 (IL-34) is a hematopoietic cytokine that has a role in the differentiation of macrophages and osteoclastogenesis. IL-34 overexpression has been linked to rheumatic autoimmune diseases as rheumatoid arthritis and PsA . Upregulated IL-34 has also been seen in human atherosclerotic plaques, especially in unstable plaques, suggesting that IL-34 has proinflammatory actions which may increase susceptibility to the incidence of acute coronary syndrome and death .
Our aim in this work was to evaluate the serum level of IL-34 in PsA patients and correlate its level and disease activity, and subclinical atherosclerosis.
Patients and methods
This is a single-center case–control study.
Patients were selected from the outpatient clinic of Rheumatology and Rehabilitation Department, Tanta University Hospitals. Supplement 1 shows the consort flow diagram of this study.
Seventy patients meeting CASPAR criteria for PsA  and 70 healthy volunteers matched for age and sex were included in this study. Patients with other dermatological or rheumatic disorders, obese (BMI > 30), cardiac patients, patients with hypertension, diabetics, acute illness, pregnant women, and patients receiving medications affecting lipid metabolism (as lipid-lowering agents, corticosteroids > 10 mg/day, B-blockers, oral contraceptive pills, thyroxin, and vitamin E) were excluded.
Ethics approval and consent to participate
This study is in agreement with the ethical guidelines of the Declaration of Helsinki and it follows the ethical standards of Tanta Faculty of Medicine, with the institution’s ethics board approval number 35413/4/22. Informed written consent from all patients was obtained in accordance with the local ethical committee. Privacy of all patients’ data was granted as there was a code number for every patient file that included all investigations.
Demographic data and detailed medication history were taken. PSA activity using Disease Activity Index for Psoriatic Arthritis (DAPSA) score  was measured using tender and swollen joint counts, patient pain and patient global assessments, and acute phase reactants.
Routine laboratory investigations
High sensitivity C reactive protein (hs CRP) concentrations were measured using the Diamed Eurogen CRP ELISA kit. ESR (mm/h) was determined by Westergren method. Total lipid profile [total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL)] also were measured on KONILAB Prime 60i Thermo Scientific-Finland autoanalyzer.
Specific laboratory investigations
By using quantitative enzyme-linked immunosorbent assay (ELISA); Serum IL-34 level was measured using (kits: WH-1752, Wkea Med Supplies Corp., Changchun, Jilin, China). Two milliliters of venous blood was collected and kept at – 70 °C until analyzed, using sandwich enzyme immunoassay technique. A monoclonal antibody specific for IL-34 has been pre-coated onto a microplate. Standards and samples were pipetted into the wells and any IL-34 present was bound by the immobilized antibody. An enzyme-linked polyclonal antibody specific for Il-34 was added to the wells after washing away any unbound substances. Then, a substrate solution was added to the wells and color develops in proportion to the amount of IL-34 bound in the initial step. The intensity of the color was measured after the color development was stopped under 450 nm wavelength.
All patients had a complete transthoracic echocardiography examination with a GE Vivid 7 Dimension echo machine with S4 transducer, which included two-dimensional, color, and Doppler (continuous and pulsed wave) as well as tissue Doppler. The images were obtained from apical and left parasternal windows, with patients lying in the lateral left decubitus position.
The following measurements were taken in accordance with the American Society of Echocardiography’s recommendations . Left atrial end-systolic diameter (LAESD), left ventricular end-diastolic diameter (LVEDD), right ventricular end-diastolic diameter (RVEDD), left ventricular posterior wall end-diastolic thickness (LVPWEDT), interventricular septum end-diastolic thickness (IVSEDT), ejection fraction (EF), fractional shortening (FS), and aortic root diameter (AO) were measured.
LV diastolic function was assessed by measuring the mitral flow velocity recorded in the apical four-chamber view by trans-mitral pulsed-wave Doppler sampling. The parameters included peak early diastolic velocity (E wave; m/s) and late diastolic velocity (A wave; m/s), E to A ratio (E/A), E wave deceleration time (DT; ms), isovolumetric relaxation time (IVRT; ms), pulsed-wave (pw), moreover, tissue Doppler imaging of the mitral annulus velocities (TDI): early diastolic (É) and late diastolic (Á) velocity and É/Á ratios were measured.
Diastolic dysfunction was defined by the presence of one of the following patterns:
Impaired relaxation pattern if E/A ratio was < 1.1, DT > 240 ms, IVRT > 90 ms, and A-pw < 25 cm/s.
Pseudonormalized pattern if E/A ratio was between 1.1 to 1.5, DT between 160 and 240 ms, IVRT between 60 and 90 ms, and A-pw > 25 cm/s.
Restrictive pattern was considered to be present if E/A ratio was > 1.5, DT < 160 ms, IVRT < 60 ms, and A-pw > 25 cm/s .
In the supine position, a resting standard 12-lead ECG was recorded at 25 mm/s chart speed and 1 mm/mv calibration. The following ECG characteristics were assessed: abnormalities consistent with myocardial ischemia, PR interval, QT interval, QRS duration, electrical axis, and presence of rhythm disorders; premature beats, low voltage, atrioventricular conduction disorders, and intraventricular conduction disturbances .
Carotid intima-media wall thickness (cIMT) assessment
SAMSUNG MEDISON (UGEO H60) with a linear transducer (midfrequency 10 MHz) was used to evaluate the common carotid arteries. cIMT was defined as the distance from the leading edge of the lumen–intima interface to the leading edge of the media–adventitia interface of the far wall. cIMT of the common carotid artery was measured between 1 and 3 cm proximal to the bifurcation of the carotid artery on the left and right sides. cIMT was measured at the distal wall of the carotid artery on a 10-mm segment . Increased cIMT was defined as ≥ 0.9 mm. Carotid plaque.was defined as cIMT ≥ 1.2 mm . The recorded scans of patients and controls were independently analyzed by two ultrasound operator.
Assessment of the serum levels of il-34 in PSA patients.
Correlates between il-34 level and disease activity, and subclinical cardiovascular affection.
Data were statistically analyzed using SPSS version 20, described in terms of mean ± standard deviation (SD). Student’s t test for independent samples when variables were normally distributed. For comparing categorical data, Chi-square test was performed. Correlation between variables was examined using Pearson’s correlation coefficient. Multiple regression analysis was used to identify variables that may correlate independently with IL-34. P values less than 0.05 were considered statistically significant .
Seventy PSA patients and seventy controls were enrolled in this study. Age, sex, BMI, smoking, and blood pressure measurements did not significantly differ between patients and controls. The mean duration of psoriasis was 7.25 ± 3.75 years, while the mean duration of PSA was 3.74 ± 1.63 years. Forty-nine patients were on csDMARDS [43 methotrexate (MTX), 6 sulfasalazine (SSZ)], and 40 were on bDMARDs (14 anti-TNF, 26 anti-IL17). Twenty-one patients on bDMARDs receiving monotherapy, while 19 receiving combined therapy with csDMARDs (13 with MTX and 6 with SSZ). The DAPSA score indicated that eight patients were in remission, and the mean DAPSA score was 11.65 ± 6.82. The clinical and demographic data for both patients and controls were displayed in (Table 1).
There were significant differences between PsA patients and controls; ESR, hs-CRP, total lipid profile, and serum levels of IL-34 were elevated in PsA patients compared to controls. Also, there was a significant difference between PsA patients and controls in measuring cIMT, while there were no significant differences regarding Echo and ECG results. Laboratory and cardiac assessments were summarized in (Table 2). Figure 1 showed cIMT findings in PsA patient.
When we compared active patients with patients who were in remission or mild activity we found that there were significant elevation in DAPSA score, hs-CRP, IL-34, and cIMT in the active patients, while there was no significant difference regarding age, BMI, duration of PSA, and ESR. These findings were summarized in (Table 3).
We found that IL-34 had significant positive correlations with DAPSA score, hs-CRP, and cIMT (r = 0.654, 0.579, and 0.658 respectively). The correlation between serum IL-34 and different clinical, laboratory and radiological findings were summarized in (Table 4).
Multiple regression analysis was used to identify variables that may correlate independently with IL-34, so; IL-34 was the dependent variable and DAPSA, hsCRP, and cIMT were the independent variables we found that all the variables evaluated had strong associations with IL-34. The odds ratio OR (95% CI) were 4.185 (0.338–51.771), 2.346 (0.286–18.749), and 2.814 (0.488–15.858) respectively.
Also, multivariable linear regression analysis [with 95% confidence interval (CI)] demonstrated that cIMT was associated only with IL-34, and DAPSA score, these relations were summarized in (Table 5).
In our study, we discovered that PsA patients’ serum IL-34 levels were substantially greater than those of normal controls and IL-34 level was significantly higher in active PsA than patients in remission or low disease activity. This was consistent with earlier studies that found that PsA patients’ serum levels of IL-34 were higher than those of people without arthritis and normal controls [21, 22].
Tian et al.  found that serum levels of IL-34 had a significant relation with disease activity in RA patients.
A non-redundant role in skin homeostasis is played by IL-34, a hematopoietic proinflammatory cytokine. Autoimmune disorders are connected with IL-34 over-expression .
In this study, there were significant positive correlations between IL-34 and the DAPSA score and hs-CRP. According to previous studies by Farrag D. et al. , the serum IL-34 level correlated significantly with the composite psoriasis disease activity index, BASDAI, peripheral joint score, and dactylitis score in the PsA group. This suggests a link between IL-34 serum levels and psoriatic disease activity, especially arthritis, but no correlation between IL-34 serum levels and radiographic joint damage scores in the hands and feet of PsA patients was detected.
IL-34 displays pleiotropic biological effects in particular tissues and cell types, including myeloid cells, epithelial cells, endothelial cells, fibroblasts, neurons, and cancer cells, from inflammatory to autoimmune disorders, IL-34 appears to be connected to a wide range of conditions. It has been demonstrated that IL-34 increases the proliferation of Th17 cells, transcription factor expression, and IL-17 production, all of which are known to be crucial in the pathogenesis of PsA .
In this study there was a significant difference between PsA patients and controls in measuring cIMT. CIMT was higher in the active patients, also IL-34 had significant positive correlations with cIMT.
Hodis et al. concluded that the increase of 0.1 mm IMT increases the likelihood of an acute myocardial infarction by 11% . As found by evaluating the carotid intima-media thickness, endothelial functions were found to be compromised in PsA patients, demonstrating a significant association between PsA and subclinical atherosclerosis as cIMT was higher in PsA patients than in healthy controls [26, 27]. In controversy, Apraş Bilgen et al.  reportedno significant difference in cIMT between the PsA patients and the controls and this can be attributed to greater use of anti-TNF-alpha treatment (76.7% of PsA patients received anti-TNF-alpha) which was reported to reduce cIMT .
However, it had been reported that the increased cIMT was not correlated with parameters of disease activity and there is no difference in cIMT between patients with and without an active joint lesion [2, 18, 29].
The c-IMT was higher in PsA patients on DMARDs than in those on TNF-α blockers. Inflammation reduction may disrupt the series of events that increases vascular risk in PsA patients .
The mechanism underlying inflammation-induced atherogenicity is complex. Cardiovascular disease has been linked to elevated CRP levels, which may affect arterial elasticity. Along with established cardiovascular risk factors (hypertension, hyperlipidemia, diabetes mellitus, smoking, family history), inflammatory cytokines like IL-1, IL-6, and TNF- have been identified as important factors [31, 32].
IL-34 can increase the production of chemokines and cytokines such as IL-6, IL-8, and C motif chemokine ligand 2 (CCL2). Additionally, TNF and IL-1 can increase the expression of IL-34, denoting that IL-34 may function as a pro-atherogenic agent. IL-34 may encourage angiogenesis through the activation of CD14 bright CD16 + monocytes. IL-34 may have an impact on the process of atherosclerosis and ischemic myocardial damage by regulating monocyte migration and macrophage differentiation [33, 34].
This study has certain limitations because it was single-centered; a multicenter study would have been better, in addition to a relatively small number of participants. Future longitudinal studies are required to evaluate the relationship between IL-34 and disease activity, as well as cardiovascular risks in PsA patients, as our study was cross-sectional.
Serum interleukin-34 is an important marker in PsA as its levels were elevated in PsA patients and correlated with disease activity, and subclinical atherosclerosis.
Availability of data and materials
Data will be available when reasonable request.
Carotid intima-media thickness
C motif chemokine ligand 2
Disease Activity Index for Psoriatic Arthritis
Enzyme-linked immunosorbent assay
- hs CRP:
High sensitivity C-reactive protein
Isovolumetric relaxation time
Interventricular septum end-diastolic thickness
Left atrial end-systolic diameter
Left ventricular end-diastolic diameter
Left ventricular posterior wall end-diastolic thickness
Right ventricular end-diastolic diameter
Tissue Doppler imaging
Tabra SA, Abd Elghany SE, Amer RA et al (2022) Serum interleukin-23 levels: relation to depression, anxiety, and disease activity in psoriatic arthritis patients. Clin Rheumatol 21:1–9. https://doi.org/10.1007/s10067-022-06300-1
Apraş Bilgen Ş, Kalyoncu U, Erden A et al (2018) Assessment of subclinical atherosclerosis in psoriatic arthritis patients without clinically overt cardiovascular disease or traditional atherosclerosis risk factors. Turk Kardiyol Dern Ars 46:358–365. https://doi.org/10.5543/tkda.2018.36169
Tyrrell PN, Beyene J, Feldman BM, McCrindle BW, Silverman ED, Bradley TJ (2010) Rheumatic disease and carotid intima-media thickness: a systematic review and meta-analysis. Arterioscler Thromb Vasc Biol 30:1014–1026. https://doi.org/10.1161/ATVBAHA.109.198424
Horreau C, Ponplard C, Brenaut E, Barnetche T, Misery L, Cribier B et al (2013) Cardiovascular morbidity and mortality in psoriasis and psoriatic arthritis: a systematic literature review. J Eur Acad Dermatol Venerol 27:12–29. https://doi.org/10.1111/jdv.12163
Ernste FC, Sánchez-Menéndez M, Wilton KM, Crowson CS, Matteson EL, Maradit KH (2015) Cardiovascular risk profile at the onset of psoriatic arthritis: a population-based cohort study: PsA and risk of CVD. Arthritis Care Res 67(7):1015–1021. https://doi.org/10.1002/acr.22536
Khraishi M, Aslanov R, Rampakakis E, Pollock C, Sampalis JS (2014) Prevalence of cardiovascular risk factors in patients with psoriatic arthritis. Clin Rheumatol 33:1495–1500. https://doi.org/10.1007/s10067-014-2743-7
Burke GL, Evans GW, Riley WA et al (1995) Arterial wall thickness is associated with prevalent cardiovascular disease in middle-aged adults: the Atherosclerosis Risk in Communities (ARIC) Study. Stroke 26:386–391. https://doi.org/10.1161/01.str.26.3.386
Allan PL, Mowbray PI, Lee AJ, Fowkes FG (1997) Relationship between carotid intima-media thickness and symptomatic and asymptomatic peripheral arterial disease: the Edinburgh Artery Study. Stroke 28:348–353. https://doi.org/10.1161/01.STR.28.2.348
Nada DW, El Morsy S, Abu-Zaid MH, Aboelhawa MA, Zakaria MA, El Sheikh EA, Gaber RA (2018) The role of microalbuminuria as a predictor of subclinical cardiovascular events in rheumatoid arthritis patients and its relation to disease activity. Clin Rheumatol 37(3):623–630. https://doi.org/10.1007/s10067-017-3849-5
O’Leary DH, Polak JF, Kronmal RA, Manolio TA, Burke GL, Wolfson SK (1999) Carotid-artery intima and media thickness as a risk factor for myocardial infarction and stroke in older adults. Cardiovascular Health Study Collaborative Research Group. N Engl J Med 340:14–22. https://doi.org/10.1056/NEJM199901073400103
Lin H, Lee E, Hestir K, Leo C, Huang M, Bosch E et al (2008) Discovery of a cytokine and its receptor by functional screening of the extracellular proteome. Science 320(807):11. https://doi.org/10.1126/science.1154370
Chemel M, Le Goff B, Brion R, Cozic C, Berreur M, Amiaud J et al (2012) Interleukin 34 expression is associated with synovitis severity in rheumatoid arthritis patients. Ann Rheum Dis 71:150. https://doi.org/10.1136/annrheumdis-2011-200096.doi:10.1136/annrheumdis-2011-200096
Taylor W, Gladman D, Helliwell P, Marchesoni A, Mease P, Mielants H, CASPAR Study Group (2006) Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum 54(8):2665–73. https://doi.org/10.1002/art.21972
Aletaha D, Alasti F, Smolen JS (2017) Disease activity states of the DAPSA, a psoriatic arthritis specific instrument, are valid against functional status and structural progression. Ann Rheum Dis 76(2):418–421. https://doi.org/10.1136/annrheumdis-2016-209511
Gottdiener JS, Bednarz J, Devereux R, Gardin J, Klein A, Manning WJ et al (2004) American Society of Echocardiography recommendations for use of echocardiography in clinical trials: a report from the American Society of Echocardiography’s Guidelines and Standards Committee and The Task Force on Echocardiography in Clinical Trials. J Am Soc Echocardiogr 17:1086–1119. https://doi.org/10.1016/j.echo.2004.07.013
Little WC, Cheng CP (1998) Diastolic dysfunction. Cardiol Rev 6(4):231–239
Kligfield P, Gettes LS, Bailey JJ, Childers R, Deal BJ, Hancock EW et al (2007) Recommendations for the standardization and interpretation of the electrocardiogram: part I: The electrocardiogram and its technology: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology. Circulation. 115(10):1306–24
Kimhi O, Caspi D, Bornstein NM, Maharshak N, Gur A, Arbel Y et al (2007) Prevalence and risk factors of atherosclerosis in patients with psoriatic arthritis. Semin Arthritis Rheum 36(4):203–209. https://doi.org/10.1016/j.semarthrit.2006.09.001
Naqvi TZ, Lee M-S (2014) Carotid intima-media thickness and plaque in cardiovascular risk assessment. JACC Cardiovasc Imaging 7(10):1025–1038
Kirkpatrick LA, Feeney BC (2013) A simple guide to IBM SPSS statistics for version 20.0 student ed. Wadsworth, Cengage Learning, Belmont, Calif.
Farrag D, Asaad M, Ghobrial CK (2017) Evaluation of IL-34 in psoriasis and psoriatic arthritis patients: Correlation with disease activity and severity. The Egyptian Rheumatologist 39:25–33. https://doi.org/10.1016/j.ejr.2016.05.008
Li J, Liu L, Rui W, Li X, Xuan D, Zheng S et al (2017) New interleukins in psoriasis and psoriatic arthritis patients: the possible roles of interleukin-33 to interleukin-38 in disease activities and bone erosions. Dermatology 233(1):37–46
Tian Y, Shen H, Xia L, Lu J (2013) Elevated serum and synovial fluid levels of interleukin-34 in rheumatoid arthritis: possible association with disease progression via interleukin-17 production. J Interferon Cytokine Res 33:398–401
Li X, Lei Y, Gao Z, Zhang B, Xia L, Lu J, Shen H (2020) Effect of IL-34 on T helper 17 cell proliferation and IL-17 secretion by peripheral blood mononuclear cells from rheumatoid arthritis patients. Sci Rep 10(1):22239. https://doi.org/10.1038/s41598-020-79312-z
Hodis HN, Mack WJ, LaBree L et al (1998) The role of carotid arterial intima media thickness in predicting clinical coronary events. Ann Intern Med 128(4):262–9. https://doi.org/10.7326/0003-4819-128-4-199802150-00002
Báñez-Bosch R, Restrepo-Velez J, Medina-Malone M, Garrido-Courel L, Paniagua-Zudaire I, Loza-Cortina E (2017) High prevalence of subclinical atherosclerosis in psoriatic arthritis patients: a study based on carotid ultrasound. Rheumatol Int 37(1):107–112
Eder L, Zisman D, Barzilai M, Laor A, Rahat M, Rozenbaum M et al (2008) Subclinical atherosclerosis in psoriatic arthritis: a case-control study. J Rheumatol 35(5):877–882 (PMID: 18381785)
Jókai H, Szakonyi J, Kontár O, Marschalkó M, Szalai K, Kárpáti S et al (2013) Impact of effective tumor necrosis factor- alfa inhibitor treatment on arterial intima-media thickness in psoriasis: results of a pilot study. J Am Acad Dermatol 69:523–529
Mazlan SA, bin Mohamed Said MS, Hussein H, binti Shamsuddin K, Shah SA, Basri H (2009) A study of intima media thickness and their cardiovascular risk factors in patients with psoriatic arthritis. Acta Medica (Hradec Kralove) 52(3):107–16. https://doi.org/10.14712/18059694.2016.114
Di Minno MN, Iervolino S, Peluso R, Scarpa R, Di Minno G, CaRRDs study group (2011) Carotid intima-media thickness in psoriatic arthritis: differences between tumor necrosis factor-α blockers and traditional disease-modifying antirheumatic drugs. Arterioscler Thromb Vasc Biol. 31(3):705–12. https://doi.org/10.1161/ATVBAHA.110.214585
Duewell P, Kono H, Rayner KJ, Sirois CM, Vladimer G, Bauernfeind FG et al (2010) NLRP3 inflammasomes are required for atherogenesis and activated by cholesterol crystals. Nature 464(7293):1357–1361. https://doi.org/10.1038/nature08938
Goronzy JJ, Weyand CM (2006) Immunosuppression in atherosclerosis: mobilizing the opposition within. Circulation 114(18):1901–1904. https://doi.org/10.1161/CIRCULATIONAHA.106.656751
Eda H, Zhang J, Keith RH, Michener M, Beidler DR, Monahan JB (2010) Macrophage-colony stimulating factor and interleukin-34 induce chemokines in human whole blood. Cytokine 52:215–220. https://doi.org/10.1016/j.cyto.2010.08.005
Robbins CS, Chudnovskiy A, Rauch PJ, Figueiredo JL, Iwamoto Y, Gorbatov R et al (2012) Extramedullary hematopoiesis generates Ly-6C (high) monocytes that infiltrate atherosclerotic lesions. Circulation 125:364–374. https://doi.org/10.1161/CIRCULATIONAHA.111.061986
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Ethics approval and consent to participate
All steps are performed according to the revised ethical principles of the Declaration of Helsinki in 2000, and local ethical and methodological protocols for approval of the study were followed.
This study is in agreement with the ethical guidelines of the Declaration of Helsinki and it follows the ethical standards of Tanta Faculty of Medicine, with the institution's ethics board approval number 35413/4/22. Informed written consent from all patients was obtained in accordance with the local ethical committee. Privacy of all patients’ data was granted as there was a code number for every patient file that included all investigations.
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M H Abu-Zaid is associate editor in ERAR Journal. The rest of the authors declare that they have no competing interests.
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Tabra, S.A., Abu-Zaid, M.H., Elsharaby, R.M. et al. Serum Interleukin-34 in Psoriatic arthritis patients and its correlation with disease 1 activity, and subclinical atherosclerosis. Egypt Rheumatol Rehabil 50, 18 (2023). https://doi.org/10.1186/s43166-023-00183-z