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. 2021 Sep 10;16(9):e0255854. doi: 10.1371/journal.pone.0255854

Serum chemerin levels: A potential biomarker of joint inflammation in women with rheumatoid arthritis

Fabiola Gonzalez-Ponce 1,, Jorge I Gamez-Nava 1,2,3,, Emilio E Perez-Guerrero 4, Ana M Saldaña-Cruz 1, Maria L Vazquez-Villegas 2,5, Juan M Ponce-Guarneros 1,6, Miguel Huerta 7, Xochitl Trujillo 7, Betsabe Contreras-Haro 8, Alberto D Rocha-Muñoz 8, Maria O Carrillo-Escalante 2, Esther N Sanchez-Rodriguez 1, Eli E Gomez-Ramirez 1, Cesar A Nava-Valdivia 9, Ernesto G Cardona-Muñoz 1,*, Laura Gonzalez-Lopez 1,2,10,*; on behalf of the Research Group for the Assessment of Prognosis Biomarkers in Autoimmune Disorders
Editor: Masataka Kuwana11
PMCID: PMC8432803  PMID: 34506500

Abstract

Background

Chemerin has a potential role in perpetuating inflammation in autoimmune diseases. Nevertheless, to date, there is no conclusive information on whether high chemerin levels increase the severity of rheumatoid arthritis (RA). Therefore, this study evaluated whether serum chemerin is a biomarker of disease activity in RA patients.

Methods

Study design: cross-sectional. The assessment included clinical and laboratory characteristics, body mass index (BMI) and fat mass. The severity of the disease activity was identified according to the DAS28-CRP index as follows: A) RA with a DAS28-CRP≤2.9 (remission/mild activity) and B) RA with a DAS28-CRP>2.9 (moderate/severe activity). Serum chemerin concentrations were measured by ELISA, and ≥103 ng/mL was considered a high level. Logistic regression analysis was applied to determine whether high chemerin levels were associated with disease activity in RA after adjusting for confounders. Multiple regression analysis was performed to identify variables associated with chemerin levels.

Results

Of 210 RA patients, 89 (42%) subjects had moderate/severe disease activity and had higher serum chemerin levels than patients with low disease activity or remission (86 ± 34 vs 73± 27; p = 0.003). Serum chemerin correlated with the number of swollen joints (r = 0.15; p = 0.03), DAS28-CRP (r = 0.22; p = 0.002), and C-reactive protein levels (r = 0.14; p = 0.04), but no correlation was observed with BMI and fat mass. In the adjusted logistic regression analysis, high chemerin levels (≥103 ng/mL) were associated with an increased risk of moderate/severe disease activity (OR: 2.76, 95% CI 1.35–5.62; p = 0.005). In the multiple regression analysis, after adjusting for potential confounders, serum chemerin levels were associated with higher DAS28-CRP (p = 0.002).

Conclusions

Higher chemerin levels increased the risk of moderate and severe disease activity in RA. These results support the role of chemerin as a marker of inflammation in RA. Follow-up studies will identify if maintaining low chemerin levels can be used as a therapeutic target.

Introduction

Rheumatoid arthritis (RA) is an inflammatory, chronic, progressive disease involving synovial joints and characterized by bone and cartilage erosions associated with a progressive decrease in joint functioning, leading to disability and impaired quality of life [1]. One of the main clinical challenges in RA, is the persistence of joint inflammation in many patients despite treatment with synthetic disease-modified antirheumatic drugs (synthetic DMARDs) or with biologic disease-modified antirheumatic drugs (biologic DMARDs) [24].

Several biomarkers of disease activity have been proposed in these patients, of them the most used are C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) included in most indices of disease activity, including the Disease Activity Score of 28 Joints (DAS28) [3, 5]. Recently, some adipokines were found to be involved in several inflammatory processes lead by the immune system [6]. Among these adipokines, chemerin has been identified as a molecule implicated in the inflammation mediated by immune mechanisms [7]. Chemerin is a chemoattractant adipokine secreted by immature dendritic cells and macrophages that binds to the G-protein coupled receptor CMKLR1 (ChemR23) [8]. Chemerin participates in adipocyte regulation and has proinflammatory activity in endothelial cells [9]. Chemerin stimulates macrophage and dendritic cell adhesion and maturation. Chemerin also has a role in the activation of fibroblast cells and synoviocytes [7]. Some previous studies have described a possible relationship between chemerin and inflammation in RA patients [7, 10]. Ha et al. identified increased chemerin in RA compared with controls, and the severity of the disease activity was correlated with the elevated chemerin levels [11]. Additionally, several published works have identified that chemerin levels can decrease in response to biologic DMARDs [1214]. Of these studies, Herenius et al. identified a decrease in chemerin in RA patients treated with adalimumab [12]. Similarly, Makrilakis et al. found that after 6 months of treatment with tocilizumab, there was a decrease in the serum levels of chemerin [13]. Finally, Fioravanti et al. found that although tocilizumab can induce a decrease in chemerin levels, this reduction was not correlated with other parameters of disease activity [14].

Recently, our group have reported the results of a study assessing the relation between chemerin levels and functional disability [15]. In this report performed in a small group of patients with RA, was identified that those subjects with impairment in the functioning had increased serum chemerin levels, mainly among patients who had high disease activity [15]. In persons with noninflammatory rheumatic disorders, chemerin levels are associated with obesity and metabolic syndrome [16]. In early RA patients managed using the treat to target strategy, Tolusso et al. identified that chemerin levels can be considered a predictor of early remission of inflammation [17]; however, other studies are required to validate these findings. These data published in the literature support the hypothesis that chemerin levels are related to disease activity in RA [11, 15, 18]. Nevertheless, there are no previous studies assessing the relation between the persistence of disease activity in RA patients treated with DMARDs and serum chemerin levels.

Therefore, the objective of this study was to evaluate whether serum chemerin is an independent biomarker of moderate or severe disease activity in RA patients.

Patients and methods

We included 210 women with RA being attended at a secondary-care hospital in Guadalajara, Mexico. They voluntarily agreed to be included in this study.

Ethics and consent

This observational study was designed following the principles of the 64th Declaration of Helsinki (last revision Fortaleza, Brazil 2013) and the national regulations for research studies in humans. The Research and Ethics Committee of the Hospital General Regional #110 del Instituto Mexicano del Seguro Social in Guadalajara, Mexico, approved this study (code of approval: R-2016-1303-11). All participants in this study signed a voluntary informed consent form before study inclusion.

Inclusion criteria

a)>18 years old, b) women and c) met the 1987 American College of Rheumatology (ACR) criteria [19]. All patients were being treated at the time of the study with synthetic DMARDs and/or biologic DMARDs. We excluded patients with a history of ischemic cardiopathy, myocardial infarction and stroke, overlapping syndromes, thyroid disease, chronic renal failure (serum creatinine >1.5 mg/dL), active infections, psoriasis, cancer, or pregnancy. All patients of reproductive age had to be using a contraceptive method. Patients with type 2 diabetes mellitus were allowed to participate in the study if they were taking oral antidiabetics. Patients using insulin were excluded. Patients with hypertension were allowed to participate if they were taking antihypertensive drugs at stable doses and if they had controlled hypertension. Patients with overweight or obesity were allowed to participate, and body mass index was considered a variable to be adjusted in the statistical analysis.

Study development

Trained researchers performed a structured review of the epidemiological, clinical, and therapeutic characteristics. Disease activity was assessed using the Disease Activity Score of 28 Joints (DAS28). The DAS28 index includes four components: i) 28 swollen joint counts, ii) 28 tender joint counts, iii) a global health index perceived by the patient, and iv) an acute phase reactant (ESR or CRP) [20, 21]. We used the DAS28-CRP index to identify two groups: A) RA patients with a DAS28-CRP≤2.9 (RA in remission/mild activity) and B) RA patients with a DAS28-CRP>2.9 (RA with moderate/severe activity) [20].

We assessed physical functioning limitations using the Spanish adaptation of the Health Assessment Questionnaire Disability Index (HAQ-DI) [22]. In the HAQ-DI, RA patients self-reported the amount of difficulty perceived when performing daily living activities, reflecting the impairment of functioning in the previous week. A higher score in the HAQ-DI indicates more functional disability [22].

Determination of Body Mass Index (BMI)

BMI was determined using the Quetelet formula (weight (kg)/height (m)2) [23].

Determination of fat mass (%)

Fat mass (%) was assessed by trained researchers using dual-energy X-ray absorptiometry (DXA) (LUNAR 2000, Prodigy Advance; General Electric equipment, Madison, WI, USA).

Chemerin level determination

Serum chemerin levels were quantified using an enzyme-linked immunosorbent assay (ELISA) (Quantikine, R&D Systems Human Chemerin Immunoassay). The sensitivity of this assay was 7.80 pg/mL, and the samples were double-checked.

Other laboratory studies

Rheumatoid factor IU/mL (RF) and C-reactive protein mg/dL (CRP) were quantified using nephelometry. Anti-cyclic citrullinated peptide antibodies (anti-CCP) were determined by ELISA using second-generation anti-CCP (anti-CCP2) RU/mL (Euroimmun, Medizinische Labordiagnostika, Germany). Cutoff points: RF >20 IU/mL; CRP >10 mg/L; anti-CCP2 >5 RU/mL.

Statistical analysis

Quantitative variables are expressed as the mean ± standard deviation (SD), and qualitative variables as frequencies (%). Student’s t-tests were computed to compare means between groups. Chi-square tests were used to compare proportions between groups. Pearson correlation tests were used to identify the strength of the association between chemerin, DAS28-CRP, BMI, fat mass (%) and other quantitative variables. Because there is no established cutoff point of high levels of chemerin, we identified higher levels in our RA population by selecting the cutoff point from levels equal to or above the 80th percentile of our data; then the cutoff for high chemerin levels was considered ≥103 ng/mL.

A multivariate logistic regression model was used to identify variables associated with disease activity. The final model was obtained using forward stepwise analysis with adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). A multivariate multiple regression analysis was used to test the variables related to chemerin concentrations. All variables with a p value ≤0.1 in the bivariate analysis were included in the multivariate analysis. We used R version 4.0.3 (R Core Team 2020) to perform the statistical analyses. Figures were constructed in R using the ggplot2 package. A p-value ≤0.05 was considered statistically significant.

Results

Fig 1 shows the study flowchart. Although 264 women with RA being treated at an outpatient clinic were screened for inclusion, we excluded 54 patients for the following reasons: hypothyroidism n = 17, cancer n = 2, overlapping syndromes n = 7, current infection n = 15, serum creatinine >1.5 mg/dL n = 1, psoriasis n = 1, history of ischemic cardiovascular disease n = 4, and inadequate blood sample for the quantification of chemerin n = 7. Consequently, we included 210 women with RA for the analysis. Of the 210 patients with RA, 121 were classified as remission or mild disease activity, and 89 were classified as moderate or severe disease activity.

Fig 1. Study flowchart.

Fig 1

Comparison of clinical characteristics between RA in remission/mild activity versus RA with moderate or severe activity

Table 1 describes the characteristics of all patients with RA. The mean age of these women with RA was 56.59 ± 11.25 years and they had a mean disease duration of 12.59 ± 8.58 years. Among these patients, 99% were receiving synthetic DMARDs. Among the total patients who were included, 77% were receiving glucocorticoids. In data that are not shown in the tables, all but one of the patients was receiving synthetic DMARDs: methotrexate (63%), leflunomide (36%), sulfasalazine (31%), chloroquine (14%) or azathioprine (14%). Combination therapy with >1 DMARD was being used by 107 patients (51%). Biologic DMARDs were used by 25 (12%) of the RA patients [etanercept 18 (8.6%), rituximab 5 (2.4%), infliximab 1 (0.5%), and adalimumab 1 (0.5%)]. There were no differences in the medication regimen between the moderate/severe disease activity or mild/remission disease activity groups. Some of the patients used medications for comorbidities; of them, we found that among the patients with diabetes mellitus, 83% (24) used metformin and 17% (5) used glibenclamide; among the patients with high blood pressure, 10% (8) used beta-blockers, 10% (8) calcium blockers, 49% (40) angiotensin converting enzyme inhibitors, and 31% (25) angiotensin II receptor antagonists.

Table 1. Comparison of clinical characteristics between rheumatoid arthritis patients with remission or mild activity and those with moderate or severe activity.

Overall Disease Activity
Variables RA Moderate or severe activity (>2.9) Remission or mild activity (≤2.9) p value
n = 210 n = 89 n = 121
Age, mean ± SD 56.59 ± 11.25 56.54 ± 9.51 56.62 ± 12.42 0.958
Smoking, n (%) 18 (9) 9 (10) 9 (7) 0.494
Menopause, n (%) 164 (78) 74 (83) 90 (74) 0.129
BMI, mean ± SD 27.73 ± 4.35 27.96 ± 4.12 27.55 ± 4.52 0.499
Fat mass (%), mean ± SD 46.33 ± 5.94 47.04 ± 5.81 45.81 ± 6.00 0.141
Comorbidities
Diabetes mellitus, n (%) 29 (14) 17 (19) 12 (10) 0.057
Hypertension, n (%) 81 (39) 37 (42) 44 (36) 0.443
Disease duration, years, mean ± SD 13 ± 9 13 ± 9 12 ± 9 0.425
HAQ-DI Score, mean ± SD 0.50 ± 0.56 0.90 ± 0.58 0.21 ± 0.31 <0.001
Functional disability, n (%) 78 (37) 63 (71) 15 (12) <0.001
Swollen joints, mean ± SD 1.3 ± 3.3 2.90 ± 4.56 0.13 ± 0.69 <0.001
Painful joints, mean ± SD 2.17 ± 4.77 4.93 ± 6.35 0.14 ± 0.47 <0.001
Severity of pain, mean ± SD 37.04 ± 28.40 55.96 ± 24.70 23.13 ± 22.29 <0.001
Treatment
Glucocorticoids, n (%) 161 (77) 67 (75) 94 (78) 0.684
Synthetic-DMARDs, n (%) * 209 (99) 89 (100) 120 (99) NC
Biologic-DMARDs, n (%) 25 (12) 8 (9) 17 (14) 0.263
Laboratory measurements
Rheumatoid Factor (UI) (+), n (%) 130 (72) 56 (75) 74 (70) 0.474
ESR (mm/Hr), (+), n (%) 127 (64) 57 (70) 70 (60) 0.128
CRP (mg/L), (+), n (%) 118 (56) 55 (62) 63 (52) 0.160
Anti-CCP (RU/mL), (+), n (%) 128 (73) 50 (69) 78 (77) 0.240
Chemerin (ng/mL), mean ± SD 78.88 ± 30.48 86.16 ± 33.67 73.50 ± 26.80 0.003

Frequency of data obtained from the patients: RF: 181 patients; ESR: 198 patients; anti-CCP: 175 patients. Other variables were measured at the time of the study in the total number of patients. Abbreviations: DMARDs: Disease-Modifying Antirheumatic Drugs; Anti-CCP: Anti-Cyclic Citrulinated Peptide.

(*) Fisher’s exact test.

NC = not calculated.

In data that are not shown in tables, we compared the serum chemerin levels between RA patients with and without diabetes mellitus without observing statistical differences between these groups (78.09 ± 29.03 ng/mL vs 83.76 ± 38.60 respectively, p = 0.454). Similarly, the presence of diabetes mellitus was compared between the RA group with high levels of chemerin (≥103 ng/mL) versus RA group with normal levels of chemerin (13% vs 18% respectively, p = 0.452).

In addition, Table 1 shows the comparison between clinical characteristics of patients with remission/mild activity and those with moderate/severe activity despite treatment with biologic DMARDs or synthetic DMARDs. Compared to women with mild disease activity or remission, in women with moderate or severe disease activity, a higher HAQ-DI score (p<0.001) and elevated serum chemerin levels (p = 0.003) were identified. Women with moderate or severe disease activity had a higher frequency of functional disability (71%) (p<0.001).

Correlation between chemerin levels and clinical variables

Table 2 shows the correlations between serum chemerin levels and clinical variables. A positive correlation was found between chemerin and DAS 28-CRP (p = 0.002), CRP (p = 0.039), and swollen joints counts (p = 0.029). No other correlations were found between chemerin levels and any other variables.

Table 2. Correlation between chemerin levels and clinical variables.

Variables Chemerin
r p
Age 0.017 0.809
Disease duration -0.108 0.120
Body mass index (kg/m2) 0.043 0.535
Fat mass (%) 0.098 0.158
Swollen joints count 0.150 0.029
Painful joints count 0.119 0.087
Severity of pain 0.127 0.065
Disease Activity Score (DAS 28-CRP) 0.215 0.002
C-reactive protein (mg/dL) 0.142 0.039
Rheumatoid factor (UI) 0.049 0.516
Erythrocyte sedimentation rate (mm/Hr) 0.067 0.349
Anti-CCP (RU/mL) -0.039 0.604

Correlations were obtained using the Pearson correlation test. Abbreviations: Anti-CCP: Anti-Cyclic Citrullinated Peptide.

Fig 2 shows the comparisons of chemerin concentrations between the group with DAS28-CRP>2.9 versus DAS28-CRP≤2.9. RA patients with moderate/severe disease activity had higher chemerin levels compared to RA in remission/mild disease activity (p = 0.003).

Fig 2. Comparison of serum chemerin levels between RA with moderate/severe disease activity versus RA in remission/mild activity.

Fig 2

Comparisons of means between groups were performed using Student t-tests. A p-value of ≤ 0.05 was considered significant.

Factors associated with moderate/severe disease activity in patients with rheumatoid arthritis

Table 3 shows the results of a logistic regression analysis evaluating the risk factors for moderate or severe disease activity. In RA patients with high chemerin levels (≥103 ng/mL), the risk of moderate/severe disease activity was increased (OR: 2.76, 95% CI 1.35–5.62).

Table 3. Factors associated with moderate/severe disease activity in patients with rheumatoid arthritis in the multivariate analysis.

Dependent variable: moderate/severe disease activity
B SE OR 95% CI p-value B SE OR 95% CI p-value
Age -0.038 0.019 0.96 0.92–0.99 0.047 NIM NIM NIM NIM NIM
Menopause 1.088 0.518 2.96 1.07–8.19 0.036 NIM NIM NIM NIM NIM
Disease duration 0.024 0.018 1.02 0.98–1.06 0.173 NIM NIM NIM NIM NIM
Fat mass % 0.019 0.026 1.02 0.97–1.07 0.460 NIM NIM NIM NIM NIM
Body Mass Index -0.038 0.048 0.96 0.87–1.05 0.429 NIM NIM NIM NIM NIM
Diabetes mellitus 0.862 0.440 2.36 1.00–5.61 0.050 NIM NIM NIM NIM NIM
Chemerin ≥103 ng/mL 1.077 0.382 2.93 1.39–6.21 0.005 1.01 0.36 2.76 1.35–5.62 0.005

Multivariable logistic regression analysis. Dependent variable presence of moderate/severe disease activity. OR: odds ratios; 95% CI: 95% confidence intervals. Crude ORs were obtained using the Enter method. Adjusted ORs were obtained using the Forward stepwise method. NIM: not in the model.

Factors associated with chemerin serum levels in patients with rheumatoid arthritis

Additionally, in data that are not shown in the tables, we performed a multiple regression analysis, testing the variables associated with the serum levels of chemerin. After adjusting for age (β coefficient = 0.028; p = 0.677), disease duration (β coefficient = -0.109; p = 0.107), body mass index (β coefficient = 0.030; p = 0.665), fat mass (%) (β coefficient = 0.072; p = 0.293) and diabetes mellitus (β coefficient = 0.059; p = 0.389), disease activity (DAS28-CRP) (β coefficient = 0.215; p = 0.002) remained associated with serum chemerin levels.

Discussion

We demonstrated that in women with RA treated with synthetic DMARDs or biologic DMARDs, elevated chemerin concentrations were related to moderate or severe disease activity after adjusting for potential confounders. Serum chemerin concentrations were correlated with DAS28-CRP, swollen joint counts, and CRP, whereas a trend that was not statistically significant was observed between serum chemerin and the number of painful joints.

Some previous studies have investigated the relationship between chemerin and disease activity in RA. Ha et al. investigated 71 patients with RA and found that chemerin levels were correlated with DAS28 and that these levels were higher in active RA [11]. Herenius et al. evaluated 49 subjects with RA treated with adalimumab and observed that chemerin levels were correlated with DAS28 and ESR [12]. Mohammed Ali et al. found that serum chemerin levels were correlated with DAS28 in their RA patients [18]. The results of these studies support our findings. However, the small sample of RA patients and the presence of confounders that might modify the relation between chemerin with disease activity make necessary to include multivariate analysis, therefore our study also included a logistic regression demonstrating that chemerin concentrations are associated with moderate/severe disease activity.

Chemerin has been proposed as a proinflammatory adipokine in arthritis [24]. Changes in chemerin levels may be related to the inflammatory response in synovial cartilage, which involves chondrocytes, macrophages, dendritic cells, and natural killer cells [25]. In our study, we found a correlation between chemerin and CRP. Similar to our findings, Herenius et al. and Maijer et al. also found a correlation with CRP [12, 26]. Also consistent with these findings, our group previously reported that serum levels of chemerin were correlated with disability function in a small group of patients with RA [15].

Few studies have highlighted the use of chemerin as a predictor of active disease. Tolusso et al. analyzed the utility of chemerin with cutoff values ≥ 95.7 ng/mL (a cutoff value similar to our study of ≥103 ng/mL). Tolusso observed that their patients with those higher chemerin levels had an increased risk of active disease, and this increase remained after adjusting for other variables [17]. However, our study is the first to identify an increase of 2.76-fold in the risk of moderate/severe disease activity. Previous studies performed in patients without rheumatic disease have reported that patients with diabetes mellitus have higher levels of chemerin [27, 28]. Remarkably, in the present study, we did not observe an increase in chemerin in patients with diabetes mellitus, probably because we did not include patients with uncontrolled diabetes or patients receiving insulin.

Our findings highlight that the inflammatory events driven by chemerin are complex. Chemerin has a chemotactic function for immune cells, promoting cellular migration under inflammatory conditions [29]. Chemerin also participates in activating NF-KB, upregulating the expression of adhesion molecules on endothelial cells, and enhancing monocyte adhesion [30]. Experimental and clinical studies have shown that chemerin production can be stimulated by interleukins (IL), including IL-1β, and it is correlated with CRP, TNF-α and IL-6 in RA [31, 32]. Furthermore, chemerin increases the production of tumor necrosis factor-alpha (TNF-α), IL1-B, and IL-6 by human articular chondrocytes [33]. These previous studies highlighted the relationship between chemerin and proinflammatory molecules.

The present study identified a relationship between high chemerin levels and the severity of disease activity in RA patients; therefore, the results of this work generate new questions about the role of chemerin in the persistence of the inflammatory process in RA. Chemerin is an adipokine synthesized mainly in adipose tissue and liver, and diverse immune cell subsets, including plasmacytoid dendritic cells, macrophages and NK cells, express the chemerin receptor CMKLR1, which when activated promotes chemotaxis and modulates the immune response. In the present study, we identified an association between chemerin levels and CRP and the number of swollen joints; these findings indicate the relevance of chemerin in inflammation in RA.

Nevertheless, our study has some limitations. One of them is that this study was not able to identify changes in chemerin levels. Longitudinal studies are required to demonstrate whether variations in this adipokine might produce changes in other variables in RA. Future studies should be performed to identify whether patients who have persistently elevated chemerin levels might have differences in their therapeutic response to synthetic or biologic DMARDs. Another limitation of this study was the lack of the inclusion of men with RA. We only included women to avoid any possible bias secondary to the hormonal differences that can influence our main variables. Future studies should be conducted on men with RA to identify whether the results observed in the present study persist.

In conclusion, higher chemerin levels increased the risk of moderate and severe disease activity in RA patients. The serum chemerin levels are correlated with higher CRP levels, as well as an increase in the number of swollen joints. This study demonstrates that the association observed between high chemerin levels, and the inflammation assessed by DAS28-CRP was independent of BMI, fat mass and diabetes mellitus, and other potential confounder factors and remains in the multivariate analysis. These findings support the hypothesis that serum chemerin levels could be used as a new biomarker to identify patients with a more severe RA without an adequate response to DMARDs. Nevertheless, future follow-up studies will be required to identify whether elevated chemerin levels defined by our cutoff level can potentially predict the future failure of treatment in patients starting DMARDs. Subsequent studies should evaluate the potential value of maintaining normal chemerin levels as a therapeutic target in these patients.

Acknowledgments

Members of the Research Group for the Assessment of Prognosis Biomarkers in Autoimmune Disorders.

Senior researchers

Jorge I. Gamez-Nava, Ernesto G. Cardona-Muñoz, Laura Gonzalez-Lopez, Department of Physiology, Centro Universitario de Ciencias de la Salud, University of Guadalajara; Alfredo Celis, Department of Public Health Sciences, Centro Universitario de Ciencias de la Salud, University of Guadalajara; Miguel Huerta, Xochitl Trujillo, Centro Universitario de Investigaciones Biomedicas, University of Colima; Juan M. Ponce-Guarneros, Maria L. Vazquez-Villegas, Unidad de Medicina Familiar #4 Guadalajara, Jalisco, y #97, Magdalena, Jalisco, Instituto Mexicano del Seguro Social.

Associated researchers

Research in Clinical and laboratory analyses: Jessica Murillo-Saich, Division of Rheumatology, Allergy and Immunology, UC San Diego School of Medicine, La Jolla, CA, USA; Ana M. Saldaña-Cruz, Norma A. Rodriguez-Jimenez, Melissa Ramirez-Villafaña, Instituto de Terapeutica Experimental y Clínica, Centro Universitario de Ciencias de la Salud, University of Guadalajara; Betsabe Contreras-Haro, Alberto D. Rocha-Muñoz, Departament of Biomedical Sciences, Departament of Health-Disease as an individual Process, and División de Ciencias de la Salud, Centro Universitario de Tonalá, University of Guadalajara; Cesar A. Nava-Valdivia, Departament of Microbiology and Patology, Centro Universitario de Ciencias de la Salud, University of Guadalajara.

Statistical team

Alfredo Celis, Department of Public Health Sciences, Centro Universitario de Ciencias de la Salud, University of Guadalajara; Emilio E. Perez-Guerrero, Instituto de Investigacion en Ciencias Biomedicas, Centro Universitario de Ciencias de la Salud, University of Guadalajara.

Research fellows

Fabiola González-Ponce, Esther N. Sanchez-Rodriguez, Eli E. Gomez-Ramirez, Heriberto Jacobo-Cuevas, Yussef Esparza-Guerrero, Jose J. Gomez-Camarena, Alejandra Martínez-Hernandez, Instituto de Terapéutica Experimental y Clinica, Departament of Physiology, Centro Universitario de Ciencias de la Salud, University of Guadalajara; Maria O. Carrillo-Escalante, Doctorado de Salud Publica, Departament of Public Health Sciences, Centro Universitario de Ciencias de la Salud, University of Guadalajara.

Data Availability

All relevant data are within the manuscript.

Funding Statement

The author(s) received no specific funding for this work.

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Decision Letter 0

Masataka Kuwana

27 May 2021

PONE-D-21-15276

Serum chemerin levels: a potential biomarker of joint inflammation in women with rheumatoid arthritis

PLOS ONE

Dear Dr. Gonzalez-Lopez,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Both reviewers funs some interests in this article, but also pointed out a number of criticisms that require improvement. I ask the authors to fully respond to all comments made by the reviewers in the revised version.. 

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We look forward to receiving your revised manuscript.

Kind regards,

Masataka Kuwana, MD, PhD

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: 1. Many statements in the INTRODUCTION section contains a scientific fact that need a reference. Please, add a reference after each statement that cite a finding.

2. Exclusion criteria are not sufficient! Do author exclude patients with T2DM, hypertension, CVD,…..etc.

3. Why the means and standard deviation have no decimals? Usually means and SD contain decimals. Also, p-values should contain 3 decimals.

4. In Table 1, p-values should be re-calculated as p-value =1 is not consistent with the results. Other p-values also are incorrect.

5. In Table 2, p-values also wrong and inconsistent with the r-values. I strongly suggest re-stating the results or consulting an expert in statistics because the results are wrong!

6. Please, add the negative error bars in Figure 2.

7. In Table3, Multivariate analysis usually contain Beta(SE) results in the tables. It is not necessary to add “enter method” or stepwise method. Add the decimals to the p-values.

8. Do author make a screening for selection a patients from a specific city or hospital? If yes, Figure 1 is necessary. If not, Figure 1 is not necessary.

Reviewer #2: The Manuscript ID PONE-D-21-15276 entitled "Serum chemerin levels: a potential biomarker of joint inflammation in women with rheumatoid arthritis " can be accepted for publication in PLOS ONE after major revisions.

The purpose of the manuscript is interesting and the obtained results are promising, however, it presents some limitations which needs to be implemented before publication.

The abstract should be re-checked and ameliorated, especially the sentences about the conclusions….which are not the conclusion of the manuscript

The introduction is complete and clear, but the objective of the study should be more impressive…

Concerning method section, the authors should include the description of all the considered demographic and clinical characteristics of the patients enrolled in the study…..as well as the inclusion and exclusion criteria, comorbidities, other pharmacological treatments….

In the results, please describe the flowchart in a better way.

In table 1 please add all the data analyzed.

Please develop the conclusions of the study. The Authors should consider what all of the findings taken together mean, what are the larger implications.

They also need to clarify what advance or advances in knowledge were made by this work.

Check the main text, there are some mistake in English language.

**********

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Reviewer #1: No

Reviewer #2: Yes: Antonella Fioravanti

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PLoS One. 2021 Sep 10;16(9):e0255854. doi: 10.1371/journal.pone.0255854.r002

Author response to Decision Letter 0


11 Jul 2021

Guadalajara, Mexico July 09th, 2021

Dr Emily Chenette

Editor-in-Chief

Plos One

Ref: Submission ID PONE-D-21-15276

Dear Dr Emily, Chenette:

We are submitting the new version of the manuscript ID ab5f7e56-9b4a-4376-b0d9-1592d605fd7a entitled: “Serum chemerin levels: a potential biomarker of joint inflammation in women with rheumatoid arthritis”, containing all the modifications that were suggested by the Reviewers’. All the comments and corrections suggested by the Reviewers were considered point by point and the modifications were highlighted in yellow color in this new version of the manuscript.

The questions/corrections suggested by the Reviewers and the answers/modifications to those questions are described as follows:

Reviewer 1

1.Reviewers’ comment: Many statements in the INTRODUCTION section contains a scientific fact that need a reference. Please, add a reference after each statement that cite a finding.

Authors’ response: In accordance with the suggestion described above, we have added in the Introduction section (page 5) a reference after each statement that cite a finding. Thank you for this suggestion.

2. Reviewers’ comment: Exclusion criteria are not sufficient! Do author exclude patients with T2DM, hypertension, CVD,…..etc.

Authors’ response: In Methods section (page 7), we included in the study the patients with diabetes mellitus and hypertension. We decided to include these patients with comorbidities and then to analyze in the statistical tests if the chemerin levels were influenced by these comorbidities. In the table 1 we show a comparison of the frequency for these comorbidities. In the exclusion criteria, we have identified that RA patients with other cardiovascular diseases (history of ischemic cardiopathy, myocardial infarction and stroke) were not included.

3. Reviewers’ comment: Why the means and standard deviation have no decimals? Usually means and SD contain decimals. Also, p-values should contain 3 decimals.

Authors’ response: In accordance with the suggestion, in the Results section (page 13) we now have described in the tables and the text means and standard deviations with their decimals. We have described the p values with 3 decimals.

4. Reviewers’ comment: In Table 1, p-values should be re-calculated as p-value= 1 is not consistent with the results. Other p-values also are incorrect.

Authors’ response: We have reviewed the p-values. In the Results section (page 14), we substitute the p-value=1 by the term “NC” (not calculated). All the p-values in this new version of the manuscript contain 3 decimals.

5. Reviewers’ comment: In Table 2, p-values also wrong and inconsistent with the r-values. I strongly suggest re-stating the results or consulting an expert in statistics because the results are wrong!

Authors’ response: We have checked the accuracy of the p values, and these were consistent with the r-values. An expert in statistics was consulted, and the results were corroborated. The p values show the probability that the results were obtained by chance; whereas the r values observed in our correlations denotate the strength of the linear relationship between two quantitative variables assessed. Thank you for your comment.

6. Reviewers’ comment: Please, add the negative error bars in Figure 2.

Authors’ response: We have added the negative error bars in Figure 2. Thank you for the suggestion.

7. Reviewers’ comment: In Table3, Multivariate analysis usually contain Beta (SE) results in the tables. It is not necessary to add “enter method” or stepwise method. Add the decimals to the p-values.

Authors’ response: In the Results section, we have added in the Table 3 (page 17), the values of Beta and Standard Error. We have included in the multivariable analysis presence of diabetes mellitus as comorbid. We have removed of the columns the terms “enter method” or “stepwise method”. We have added the 3 decimals to the p-values. Thank you for these recommendations.

8. Reviewers’ comment: Do author make a screening for selection a patient from a specific city or hospital? If yes, Figure 1 is necessary. If not, Figure 1 is not necessary.

Authors’ response: We have included in the Figure 1, the information of the specific hospital where the RA patients were selected. Thank you for your suggestion.

Reviewer 2

1.Reviewers’ comment: The abstract should be re-checked and ameliorated, especially the sentences about the conclusions…. which are not the conclusion of the manuscript.

Authors’ response: We have rewritten the abstract (page 3 and 4). We have modified the conclusion. Now there is a concordance between the conclusion in the abstract and the conclusion in the text of the manuscript (page 22).

2. Reviewers’ comment: The introduction is complete and clear, but the objective of the study should be more impressive…

Authors’ response: In the Introduction section (page 6), we have modified the objective of the study according to the comments. Now the new objective is described as follows: “Therefore, the objective of this study was to evaluate whether serum chemerin is an independent biomarker of moderate or severe disease activity in RA patients”. We thank for this important suggestion.

3. Reviewers’ comment: Concerning method section, the authors should include the description of all the considered demographic and clinical characteristics of the patients enrolled in the study… as well as the inclusion and exclusion criteria, comorbidities, other pharmacological treatments….

Authors’ response: In the Method section (page 7), we have modified the inclusion criteria, to include a more detailed description of the inclusion and exclusion criteria, comorbidities, and pharmacological treatments.

4. Reviewers’ comment: In the results, please describe the flowchart in a better way.

Authors’ response: In the Results section (page 10), we have described in more detail the flowchart.

5. Reviewers’ comment: In table 1 please add all the data analyzed.

Authors’ response: In the Results section (page 13 and 14), we have added in table 1, all the data analyzed. Thank you for your suggestion.

6. Reviewers’ comment: Please develop the conclusions of the study. The Authors should consider what all of the findings taken together mean, what are the larger implications.

They also need to clarify what advance or advances in knowledge were made by this work.

Authors’ response: We have rewritten the conclusion of the study, in the text (page 22) and in the Abstract section (page 4).

7. Reviewers’ comment: What all of the findings taken together mean, what are the larger implications.

They also need to clarify what advance or advances in knowledge were made by this work.

Authors’ response: We also added relevant information regarding the interpretation of our findings in the paragraph related with the importance of our study in the Discussion section (page 21), “The present study identified a relationship between high chemerin levels and the severity of disease activity in RA patients; therefore, the results of this work generate new questions about the role of chemerin in the persistence of the inflammatory process in RA. Chemerin is an adipokine synthesized mainly in adipose tissue and liver, and diverse immune cell subsets, including plasmacytoid dendritic cells, macrophages and NK cells, express the chemerin receptor CMKLR1, which when activated promotes chemotaxis and modulates the immune response. In the present study, we identified an association between chemerin levels and CRP and the number of swollen joints; these findings indicate the relevance of chemerin in inflammation in RA”. Thank you for the suggestion.

8. Reviewers’ comment: Check the main text, there are some mistake in English language.

Authors’ response: The manuscript has been checked and corrected. The English language editing certificate was issued on June 28, 2021 and may be verified on the AJE website using the verification code 216B-E352-B7D8-E106-F506. Thank you for the suggestion.

Dr Laura Gonzalez-Lopez

Author for correspondence

Primary email: lauraacademicoudg@gmail.com

Alternative email: dralauragonzalez@prodigy.net.mx

Ernesto German Cardona

Author for correspondence

Email: cameg1@gmail.com

Attachment

Submitted filename: Response to Reviewers ID PONE-D-21-15276docx.docx

Decision Letter 1

Masataka Kuwana

26 Jul 2021

Serum chemerin levels: a potential biomarker of joint inflammation in women with rheumatoid arthritis

PONE-D-21-15276R1

Dear Dr. Gonzalez-Lopez,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Masataka Kuwana, MD, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: I Don't Know

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: All the inquiries have been addressed. I have no further concerns regarding the manuscript. Thank you.

Reviewer #2: The manuscript is well written and organize. The quality of English is good. The paper appears suitable for publication in Plos One journal.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Fioravanti Antonella

Acceptance letter

Masataka Kuwana

27 Aug 2021

PONE-D-21-15276R1

Serum chemerin levels: a potential biomarker of joint inflammation in women with rheumatoid arthritis

Dear Dr. Gonzalez-Lopez:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Prof. Masataka Kuwana

Academic Editor

PLOS ONE

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