|Ahead of print publication
Pentraxin 3 is better than conventional inflammatory markers for disease activity assessment in takayasu arteritis
Phani Kumar Devarasetti, Rajendra Varaprasad Irlapati, Liza Rajasekhar
Department of Clinical Immunology and Rheumatology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India
Department of Clinical Immunology and Rheumatology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana
Source of Support: None, Conflict of Interest: None
Objective: The objective of this study is to measure plasma pentraxin 3 (PTX3) levels in Takayasu arteritis (TA) patients and to compare the accuracy of PTX3, high-sensitive C-reactive protein (hsCRP), and erythrocyte sedimentation rate (ESR) in distinguishing active disease from the inactive disease.
Methods: In a prospective, cross-sectional study, TA patients fulfilling 1990 American College of Rheumatology criteria and healthy controls were enrolled in this study. The Indian Takayasu Clinical Activity Score (ITAS 2010) and ITAS ESR were recorded. Patients were divided into active, grumbling and inactive disease using physician global assessment. Plasma PTX3, hsCRP, and ESR were measured. Receiver operating curves for PTX3 (pg/ml), hsCRP (mg/L), and ESR (mm at 1 h) were constructed to differentiate active from the inactive disease. Inter-group comparisons were made using Mann–Whitney test.
Results: Forty patients and 20 controls with median age of 26 and 24 years, respectively, were enrolled in this study. Median disease duration was 2 years. Fourteen patients had active, 8 grumbling, and 18 inactive disease. ITAS 2010 and ITAS ESR in active disease (5 [3–8.5], 7.5 [5–11.5]) were significantly higher than grumbling (0.6 (0–1.5], 2.5 [1–4.5]) or inactive disease (0.5 [0–1.3], 2 [1.7–3]) (P = 0.001). PTX3 (pg/mL) was higher in cases (505 [261–1358]) as compared to that of controls (317 [135–450]) (P < 0.026), in active disease (1335 [464–2128]) was higher than grumbling (689 [246–2114]), but significantly higher than inactive TA (369 [145–512]) (P < 0.001). ESR (mm/h) and hsCRP (mg/L) of 49 (33–61.2), 12.9 (4–21), respectively, in active disease was similar to grumbling (44 [31–63], 10.7 [3–14.7]), but significantly higher than inactive disease (38 [24–45], 1.8 [1.4–2.2]) (P = 0.03). Sensitivity, specificity, and area under the curve for ESR (>46 mm), hsCRP (17.1 mg/L), PTX3 (>745 pg/ml) was (55, 89, and 0.72), (46, 89, and 0.75), and (64, 95, and 0.82), respectively.
Conclusion: Elevated PTX3 in TA demonstrates more accuracy than hsCRP and ESR in differentiating active from the inactive disease. These biomarkers may differentiate grumbling from inactive disease better than ITAS2010 or ITAS-ESR.
Keywords: Biomarkers, Indian Takayasu activity score 2010, inflammation, pentraxin 3, Takayasu arteritis, vasculitis
|How to cite this URL:|
Devarasetti PK, Irlapati RV, Rajasekhar L. Pentraxin 3 is better than conventional inflammatory markers for disease activity assessment in takayasu arteritis. Indian J Rheumatol [Epub ahead of print] [cited 2019 Jan 18]. Available from: http://www.indianjrheumatol.com/preprintarticle.asp?id=248776
| Introduction|| |
Takayasu arteritis (TA) is granulomatous, chronic large-vessel vasculitis affecting the aorta and its main branches, occurs predominantly in females. The diagnosis is usually made in the second or third decades of life. TA is often a smoldering disease. Therefore, assessment of disease activity and damage is challenging. Assessment of disease activity and damage is important in vasculitis to identify manifestations of the active disease that are possibly more amenable to therapy than irreversible damage which are scars left behind by prior disease activity. Measurement of acute-phase reactants such as erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) is frequently advocated for disease assessment in TA. ESR is widely used, but values are normal in 30% of patients with active inflammation and elevated in more than 40% without vascular inflammation. It is well established that vascular wall inflammation can persist and arterial lesions progress in the face of normal ESR or CRP levels, or both. Therefore, there is a need for a better biomarker to differentiate active from the inactive disease.
Pentraxin 3 (PTX3) is generally produced by endothelial cells, vascular smooth muscle cells, fibroblasts, macrophages, and dendritic cells and cardiomyocytes at local inflammatory sites throughproinflammatory cytokine stimulation. It is being studied in various rheumatic diseases such as systemic lupus erythematosus, scleroderma, and rheumatoid arthritis. In SLE and scleroderma, PTX3 was strongly correlated with disease activity scores and with pulmonary artery hypertension pointing to a dysregulated endothelial function. PTX3 is also used as a prognostic marker in cardiovascular diseases and sepsis. Limited studies are available on PTX3 as a disease activity marker in TA and comparison with conventional acute phase reactants in the assessment of disease activity., Therefore, this study was undertaken to see whether PTX3 could be a better marker in distinguishing active and inactive disease in patients with TA.
| Methods|| |
The study setting was cross-sectional and prospective conducted at a tertiary care institute in South India. Forty consecutive patients of TA attending the Rheumatology outpatient services, either newly diagnosed or on follow-up, were evaluated for disease activity scores and serum biomarkers. The recruitment of these patients was done between January 2014 and June 2015. Patients fulfilling 1990 American College of Rheumatology criteria were included in the study. These criteria includes age at disease onset <40 years, claudication of extremities, decreased brachial artery pulse, blood pressure difference in arms >10 mmHg, bruit over subclavian arteries or aorta, arteriogram abnormality - arteriographic narrowing or occlusion of the entire aorta, its primary branches, or large arteries in the proximal upper or lower extremities. Patients were classified as TA if three out of six criteria were fulfilled. Patients with sepsis, cardiac disease, chronic kidney disease, malignancy, connective tissue diseases systemic lupus erythematosus, rheumatoid arthritis, and scleroderma were excluded from the study. Twenty healthy age- and sex-matched controls were included in the study.
Based on the physician global assessment (PGA) patients were divided into active/grumbling (persistent)/inactive disease groups. PGA was based on clinical symptoms and acute-phase reactants. Clinical symptoms, such as constitutional features, new-onset carotidynia, claudication, loss of pulses, hypertension, and heart failure, were considered to categorize patients. ESR was considered elevated if it was more than 20 mm at 1 h. If a patient had any new or worsening clinical symptoms were considered active. If there were no new clinical symptoms, but persistent previous symptoms (not due to damage), with or without elevated ESR, these were considered grumbling disease. Asymptomatic patient irrespective of ESR were considered inactive.
Disease extent index Takayasu (DEI TAK), Indian Takayasu Activity Score (ITAS 2010) and ITAS-ESR were recorded for each patient. Active disease was defined as >1 for ITAS2010 and >4 for ITAS-ESR scores.
Two mL of venous blood sample were collected into ethylene diamine tetraacetic acid tubes and the plasma was separated and immediately stored at −20°C in aliquots until analysis. Plasma concentrations of PTX3 were evaluated with commercially available, highly sensitive, and specific sandwich enzyme-linked immunosorbent assay (ELISA) method based on the PTX3-specific monoclonal antibody and biotinylated goat PTX3-specific polyclonal immunoglobulin G (Boster biological technology, Fremont, CA). PTX3 levels were analyzed at 450 nm using an ELISA reader (Bio-Rad, Nova Path, California, USA). No cross-reactions with other short PTX, i.e., CRP and serum amyloid P, were seen with the present ELISA kit as per the manufacturer information. The minimum detection sensitivity of the kit was 10 pg/ml, and the results are presented as pg/ml.
High sensitivity CRP (hsCRP) was measured using sandwich ELISA. Manufacturer minimum detection sensitivity of the kit was 0.01 mg/L, and the results are presented as mg/L. ESR was measured using Westergren's method, and results are presented as mm at 1 h. Both hsCRP and ESR were measured at the same time of collection of plasma samples for PTX3 in patients, and PTX3 was measured in healthy controls.
Imaging modalities used to assess the extent of vascular involvement were Doppler ultrasound (carotid/Renal), computerized tomography angiography, magnetic resonance imaging angiography of the aorta and its branches. Vascular imaging findings of vessel wall thickening, stenosis, aneurysms, and occlusion were recorded. Based on the angiographic classification (Numano), patients were divided into five types as per extent of vessel involvement. Two-dimensional echocardiography findings were recorded for global wall hypokinesia, ejection fraction, and aortic regurgitation.
Ishikawa classification was used to group Takayasu patients based on natural history and complications of the disease into four groups. The four most important complications were defined as Takayasu retinopathy, secondary hypertension, aortic regurgitation, and aneurysm formation, each being graded as mild/moderate or severe at the time of diagnosis. This classification classifies TA patients into three groups-Group I-uncomplicated disease with or without pulmonary artery involvement, Group II subdivided into two Groups: IIA-mild/moderate single complication and IIB-severe single complication with uncomplicated disease, and Group III-two or more complications together with uncomplicated disease.
Treatment details were recorded in all patients.
Baseline demographic and clinical characteristics of patients are presented as medians (interquartile range [IQR]) and percentages. Plasma PTX3, hsCRP and ESR are expressed as medians (IQR). Values were compared between patient groups using the Mann–Whitney U-test. Receiver operating curves (ROC) were constructed, and optimal cutoff were taken with sensitivity and preference to maximal specificity for Plasma PTX3, hsCRP, and ESR in differentiating active from the inactive disease. Likelihood ratios (LR+/LR−) were calculated using sensitivity (SE) and specificity (SP) for plasma PTX3, hsCRP and ESR. Spearman rank correlation coefficient was used to describe correlations between PTX3 and hsCRP, between PTX3 and ESR, and between PTX3 and ITAS 2010/ITAS-ESR. Value of P < 0.05 was considered to represent a statistically significant difference. Statistical analysis was carried out with IBM SPSS Statistics for Windows (Version 21.0).
The study was approved by the ethics committee of the institute. Informed written consent was obtained from all patients prior to their enrollment in this study.
| Results|| |
Baseline characteristics of patients and controls are mentioned in [Table 1].
|Table 1: Baseline Demographic and clinical characteristics in Takayasu arteritis patients|
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Weight loss, fatigue, and anorexia (75%) were the most common presenting complaints followed by claudication and dyspnea. The common clinical examination findings were diminished pulses followed by bruits. Pulse loss was most common in the radial (65%), followed by brachial arteries (50%). Carotid bruits were common (53%) followed by subclavian bruits (33%).
Type I angiographic involvement was seen in 60% (24/40) of patients. Subclavian was the most commonly affected artery (77.5%) followed by the carotid (50%) and the renal artery (35%). Renal artery was involved in 14 patients, (unilateral in 9 and bilateral in 5). The most common type of arterial abnormality was stenotic lesions (44.7% of all lesions) followed by occlusion, wall thickening, and dilatation.
Aortic regurgitation was seen in seven patients (moderate to severe), requiring aortic valve replacement with root reconstruction in two patients, moderate-to-severe left ventricular dysfunction was reported in six patients. As per Ishikawa classification, 62.5% of patients were Group I, i.e., uncomplicated disease.
Disease activity scores
Based on PGA, patients were grouped into the active disease (n = 14), grumbling disease (n = 8) and inactive disease (n = 18).
The disease activity scores in patients are mentioned as median (IQR) in [Table 2]. DEI TAK was significantly higher in patients with active disease compared to patients with grumbling or inactive disease. ITAS 2010 in patients with active disease was significantly higher compared to patients with grumbling or inactive disease. ITAS-ESR in active disease was higher compared to patients with grumbling or inactive disease. DEI TAK, ITAS 2010, and ITAS-ESR were not significantly different between grumbling and inactive disease.
|Table 2: Disease activity scores in Takayasu arteritis patients grouped by physician global assessment|
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Median (IQR) ESR, hsCRP, and PTX3 of the cases and healthy controls are reported in [Table 3].
|Table 3: Laboratory markers in Takayasu arteritis patients grouped by the physician global assessment|
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ESR was significantly higher in active as compared to that of inactive disease (P < 0.026) but was not different between active and grumbling disease (P < 0.70). hsCRP was significantly higher in active disease as compared to that of inactive disease (P < 0.031) but not different between active and grumbling disease (P < 0.24). PTX3 was significantly higher in active as compared to that of inactive disease but not statistically different between active and grumbling disease. Median PTX3 (IQR) in cases and controls were 505 (261–1358) and 317 (135–450) pg/ml, respectively. PTX3 levels were significantly higher in cases as compared to that of healthy controls (P < 0.026). PTX3 levels (ng/ml) were significantly higher in active disease patients 1335 (464–2128) as compared to that of inactive disease 369 (145–512) (P = 0.04).
ROC were constructed and analyzed for sensitivity, specificity of biomarkers between two groups [Figure 1]: First group - active and grumbling disease, second group - inactive disease patients. Using the ROC curve, we determined the cutoff values for ESR (>46 mm at 1 h), hsCRP (>17.1 mg/L), and PTX3 (>745 pg/ml) to determine the SE (sensitivity), SP (specificity), and area under the curve (AUC) [Table 4].
|Figure 1: Receiver-operating characteristic curves for pentraxin 3, high sensitive C-reactive protein, and erythrocyte sedimentation rate in Takayasu arteritis patients|
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|Table 4: Receiver operating curve parameters of biomarkers for detecting active Takayasu arteritis patients|
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Positive likelihood ratio (LR+) for PTX3 to predict active disease was 12.8, compared to 4.2 for hsCRP and 5 for ESR. Negative likelihood ratio (LR−) of PTX3, i.e., its ability to predict the absence of active disease was 0.37, which was lower compared to hsCRP (0.6) and ESR (0.5).
There was significant correlation between PTX3 and ITAS 2010 (ρ =0.56, P = 0.001), ITAS-ESR (ρ = 0.60, P = 0.001) [[Figure 2] upper panel]. There was statistically significant correlation between hsCRP and ITAS 2010 (ρ = 0.49, P = 0.001), hsCRP and ITAS-ESR (ρ = 0.54, P = 0.001) [[Figure 2] lower panel]. There was no significant correlation between PTX3 and hsCRP levels (ρ = 0. 23) (P = 0.15) and between PTX3 levels and ESR (ρ = 0.39) (P = 0.12) in the entire group of patients [Figure 3].
|Figure 2: Scatter plots showing correlation between ITAS 2010/ITAS erythrocyte sedimentation rate and biomarkers. (I) Upper panel: (a) Pentraxin 3 and ITAS 2010 (b) Pentraxin 3 and ITAS ESR (II) Lower panel: (c) High sensitive C-reactive protein and ITAS 2010 (d) High sensitive C-reactive protein and ITAS ESR|
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|Figure 3: Scatter plots for showing correlation between (a) high sensitive C-reactive protein and pentraxin 3 (b) Erythrocyte sedimentation rate and pentraxin 3|
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| Discussion|| |
In this study, classification as active, grumbling, and inactive was by PGA, reiterating the fact that no true gold standard for disease activity assessment exists. This study demonstrates that plasma PTX3 is elevated in TA and a value of >631 pg/ml has a sensitivity and specificity higher than ESR and hsCRP, as depicted by a higher AUC in differentiating active from the inactive disease. It was interesting to note that the clinical scores of ITAS 2010, as well as ITAS-ESR, were similar in grumbling and inactive disease, but PTX3, ESR, and hsCRP were similar in active and grumbling disease. Since grumbling disease is perceived to be associated with higher long-term damage than the inactive disease, laboratory biomarkers may have a role to play in improving the differentiation between grumbling and inactive disease. Values of these biomarkers above the cutoff would suggest grumbling rather than the inactive disease. Plasma PTX3 provides the best AUC for this purpose.
Positive LR was higher for PTX3, suggests that it has the best ability of the three to change the probability of disease considered inactive by clinical assessment to active or grumbling disease. All the three biomarkers have a low-negative LR-suggesting that they can improve the accuracy of clinical assessment of active TA but have no value in classifying a patient as inactive if the disease is judged clinically active.
Misra et al. validated ITAS 2010/ITAS-A scores in 300 TA patients and found ITAS 2010 score was significantly higher in patients with active TA compared to those with grumbling or inactive disease as rated by the PGA, cutoff values for ITAS 2010 >2 and ITAS - A >4 were proposed to differentiate active from inactive disease. Alibaz-Oner et al. also have prospectively assessed 144 TA patients with ITAS 2010 scores and showed significantly higher scores in patients with active disease.
The higher PTX3 levels in TA compared to controls has been demonstrated in other studies too,,,, [Table 5]. Variable PTX3 levels in active and healthy controls were seen in different studies may be due to the usage of different kits for measurement. None of the studies has placed clinically active and clinically grumbling patients into different groups. This difference is important since the decision about de-escalating and stopping immunosuppressive therapy is dependent on judging the disease to be grumbling or inactive. In our study, the PTX3 values in patients with clinically grumbling disease as judged by PGA were much higher than in those with inactive disease suggesting that this marker could be valuable in such a situation since the ITAS 2010 scores do not differentiate grumbling from the inactive disease. The numbers in the grumbling group in our study are low (8), and studies with larger numbers may benefit.
|Table 5: Pentraxin 3 in disease assessment in Takayasu arteritis - previous studies|
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hsCRP in this study performed well in differentiating active from inactive disease in TA patients as shown by lower negative LR, which infers hsCRP is a good biomarker to assess activity status in TA patients. There is only one other study till date by Ishihara et al. that studied hsCRP in active and inactive disease in patients with TA.
In our study PTX3 is accurate in terms of higher AUC, higher specificity and likelihood ratios (positive and negative) in distinguishing active and inactive disease compared to hsCRP and ESR suggesting that of the three biomarkers it has the best potential to affect the pre-test probability while deciding the disease activity. These results were consistent with the study by Ishihara et al. PTX3 helped in differentiating active and inactive disease better than hsCRP.
The major limitation of our study is it is cross-sectional with a small number of patients. The utility of PTX3 and hsCRP levels in longitudinal assessment of disease activity and response to treatment was not studied. Longitudinal imaging was not used for disease activity assessment in the study.
Plasma PTX-3 levels were found to be significantly higher in TAK as compared to that of healthy controls. PTX-3 levels were higher in active as compared to that of inactive patients assessed according to various activity assessment tools. Therefore, our results support previous observations that plasma PTX-3 levels may be a discriminatory biomarker for active disease in TAK. Further studies with larger numbers in the grumbling disease group are required to identify biomarkers that could validate these biomarkers for identifying grumbling from the inactive disease so that treatment decisions could be modified.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]