Abstract
Background
In recent years, interleukin-21 (IL-21) has been found to be a key player in RA pathogenesis and progression, despite accumulating evidence on rheumatoid arthritis (RA) etiology, the precise contribution of IL-21 gene variants interacting with environmental exposures remains unexplored in population-based studies. Therefore, we performed this study to evaluate the impact of gene single nucleotide polymorphisms (SNPs) and their interaction with environment on RA risk.
Methods
In this study, Genomic DNA was extracted from whole blood samples (Invitrogen PureLink™ Genomic DNA Mini Kit), and targeted genotyping of four SNPs (rs2055979, rs12508721, rs2221903 and rs907715) of IL-21 gene was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology. Genotypic relationship testing in this case-control study was performed by using SNPStats online software (https://www.snpstats.net/), odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The interaction combinations among four SNPs and environmental factors including smoking and alcohol drinking were screened using generalized multifactor dimensionality reduction (GMDR).
Results
Logistic regression analysis showed that the risks of RA were significantly higher in carriers with rs2055979- CA genotype (OR = 1.63, 95% CI = 1.28–1.97), rs2055979-AA genotype (OR = 2.02, 95% CI = 1.47–2.59), rs2055979-AA + CA genotype (OR = 1.78, 95% CI = 1.32–2.26), compared to carriers with rs2055979-CC genotype. In allele genetic model, rs2055979-A was also associated with increased RA risk (OR = 1.72, 95% CI = 1.39–2.06). However, we did not find any significant association of rs2221903, rs907715 and rs12508721 with RA risk. The GMDR model found a statistically significant two locus model (P = 0.018), including rs2055979 and smoking, indicating that the interaction between rs2055979 and smoking was significantly associated with the risk of RA. Smokers with rs2055979-AA or CA genotype had the highest risk of RA, compared with non-smokers with rs2055979-CC genotype, OR (95% CI) was 3.23 (1.86–4.64).
Conclusions
We found that rs2055979- A allele, gene- environment interaction between rs2055979 and smoking were all correlated with increased RA risk.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12920-025-02217-1.
Keywords: Smoking, Single nucleotide polymorphisms, Interleukin-21, Rheumatoid arthritis, Interaction
Introduction
Rheumatoid arthritis (RA), a prevalent chronic autoimmune disorder affecting multiple systems, primarily manifests as inflammation targeting smaller joints. This condition progresses with gradual deterioration of joint integrity accompanied by synovitis (joint lining inflammation), culminating in structural deformities and impaired mobility [1, 2]. Worldwide, the prevalence of RA is 0.5%~1% [3]. In the Chinese population, the prevalence of RA is about 0.34% [4], and this value is still increasing [5]. The development and progression of RA are shaped by the synergistic interaction between inherited genetic susceptibility and external environmental triggers [6]. RA belongs to a complex disease involving multiple susceptible genes. Although many biological molecular mechanisms have been proposed, so far, the pathogenesis and specific etiology of RA are still not very clear in this study. It suggests that immune abnormalities may be caused by genetic, epigenetic, environmental, and hormonal interactions, leading to the occurrence of RA [7]. Consequently, systematic elucidation of the dynamic interplay among environmental exposures, genetic predispositions, and stochastic elements holds the key to deciphering the intricate molecular pathways underlying rheumatoid arthritis pathogenesis.
Interleukin-21 (IL-21), a pleiotropic immunomodulator primarily synthesized by activated CD4 + T lymphocytes and natural killer (NK) cells, exerts pleiotropic regulatory effects on both innate and adaptive immunity [8]. This cytokine demonstrates functional dichotomy within the IL-2 cytokine superfamily (including IL-2, IL-4, and IL-15) [9], with which it shares conserved structural domains. The biological activity of IL-21 is mediated through binding to the gamma subunit (γc) of its cognate receptor (IL-21R), which exhibits pan-leukocytic expression patterns. Notably, specialized T cell subsets, particularly Th17, follicular helper T (Tfh), and NKT cells-constitute the predominant cellular sources of IL-21 secretion [10].
In recent years, IL-21 has been found to be a key player in RA pathogenesis and progression [11–13]. The IL-21 gene, mapped to chromosomal region 4q27, contains five exons in regions within its genomic structure. And all selected SNPs in this study were located in the intron region. Several single-nucleotide polymorphisms (SNPs) located in IL21 region have proven to be significantly associated with several autoimmune disorders [14, 15], including RA [16, 17]. However, the results obtained from these studies were inconsistent. In addition, the pathogenesis of RA involves complex reasons, including genetic and environmental factors. Previously, several studies reported the impact of smoking on RA pathology [18, 19]. And studies also reported the gene- smoking interaction could influence RA risk in different populations [20, 21]. Despite accumulating evidence on rheumatoid arthritis etiology, the precise contribution of IL-21 genetic variants interacting with environmental exposures remains unexplored in population-based studies. Therefore, the purpose of this study is to evaluate the relationship between IL-21 gene SNPs and RA risk. We also included environmental factors in the interaction analysis models to verify the effect of the interaction between IL-21 gene SNPs and environmental factor on RA risk based on this Chinese Han populations.
Methods
Study population
A total of 816 participants with an average age of 49.5 ± 10.2 years were enrolled in this case- control study, including 406 RA patients and 410 healthy controls from March 2019 to December 2022 in the Fourth Affiliated Hospital of Soochow University hospital in Suzhou city of Jiangsu province and the Shanxi Yuncheng Central Hospital in Yuncheng city of Shanxi province. All participants were selected from RA patients diagnosed by attending physician according to the ACR/EULAR 2010 rheumatoid arthritis classification criteria [22]. RA patients with juvenile idiopathic arthritis or other autoimmune diseases were excluded from the case group. The demographics data including age, gender, BMI and family history, clinical data including RA disease duration, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide (CCP), disease activity score (DAS 28) of all patients were obtained from their medical records. Unrelated controls matching to RA patients regarding age (± 3 years) and sex were selected, while those participants with family history of RA were excluded. Those participants and their first-degree relatives who have a history of RA or any other autoimmune disease were excluded from the control group. All study protocols of the current study were approved by the ethics committee of the Fourth Affiliated Hospital of Soochow University. In this study, PASS 15.0.5 software [23] was used to calculate the sample size. The results showed that the minimum sample size was 401 pairs (power ≥ 0.95, α < 0.05, OR = 2.0, P2 = 0.12). A total of 406 pairs were enrolled in this study. Therefore, the number of RA patients met the requirements for statistical analysis.
The information on smoking and alcohol consumption status were collected by questionnaire. Current alcohol consumers were defined as those who drink more than one drink of any type per month, and current smokers were defined as those who have smoked at least 100 cigarettes and still smoked at the time of the interview [24].
Genotyping methods
A total of four SNPs within IL-21 gene were selected, including: rs2055979, rs12508721, rs2221903 and rs907715, based on HapMap data (http://hapmap.ncbi.nlm.nih.gov/) and dbSNP data (http://www.ncbi.nlm.nih.gov/projects/SNP/) according to the following the criteria: first, minor allele frequency more than 5%; second, it was reported in previous studies on association with RA susceptibility; third, the relationship between this SNP and RA susceptibility remains inconclusive.
Genomic DNA was extracted from peripheral blood samples using a commercial kit (e.g., QIAamp DNA Blood Mini Kit) following the manufacturer’s protocol. Four IL-21 gene SNPs were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Primer pairs were designed using Primer3Plus to flank each SNP (Supplementary Table 1), with amplicon sizes ranging 200–400 bp. PCR was performed in 25 µL reactions containing 50–100 ng DNA, 0.4 µM primers, 0.2 mM dNTPs, 1× PCR buffer, and 1 U Taq polymerase. Cycling conditions included initial denaturation (95 °C, 5 min), 35 cycles of denaturation (95 °C, 30 s), annealing (optimized Tm for each primer pair, 30 s), extension (72 °C, 1 min/kb), and final extension (72 °C, 10 min). Amplicons were digested with 5–10 U of restriction enzymes (supplementary Table 1) in 20 µL reactions at manufacturer-specified temperatures for 4 h. Digested products were resolved on 3% agarose gels alongside undigested controls and a 50-bp DNA ladder. Known genotype controls and 10% random replicates were included for validation.
Statistical analysis
In this study, data was calculated by using SPSS version 22.0 (SPSS Inc., Chicago, Ill., USA). Genotype and allele frequencies of rs2055979, rs12508721, rs2221903 and rs907715 were quantified through direct counting methodology, and Hardy–Weinberg equilibrium (HWE) was evaluated by the χ2 test. Odds ratios (ORs) and 95% confidence intervals (CIs) were employed to assess the effects of minor alleles of four SNPs on RA risk. Genotypic relationship testing in this case-control study was performed by using SNPStats online software (https://www.snpstats.net/) under three genetic models (codominant, dominant and allele). A Bonferroni-corrected threshold of P < 0.0125 was considered significant. The interaction combinations among four SNPs and environmental factors including smoking and alcohol drinking were screened using generalized multifactor dimensionality reduction (GMDR) [25]. And the interaction effect was evaluated by dividing participant into four groups according to the rs2055979 genotypes (CC and AA + CA) and smoking status (current or ever and never), OR (95%CI) was calculated for the other three groups compared to never smokers with rs2055979-CC genotype.
Results
A total of 816 participants with an average age of 49.5 ± 10.2 years were enrolled in this case- control study, including 406 RA patients and 410 healthy controls. Table 1 shows the demographics and clinical features of 816 participants grouped by RA patients and control group. The average values of age and body mass index (BMI) and distribution of gender were not significantly different between case and controls. The means of ESR, CRP concentrations and current or ever smoking and alcohol drinking rates were higher in RA patients than in controls.
Table 1.
Demographics and clinical features of 816 participants grouped by RA patients and control group
| Variables | RA patients (n = 406) |
Normal controls (n = 410) |
p-values |
|---|---|---|---|
| Age (year) (Mean ± SD) | 50.2 ± 11.8 | 48.7 ± 10.6 | 0.056 |
| Gender, N (%) | 0.895 | ||
| Male | 214 (52.7) | 218 (53.2) | |
| Female | 192 (47.3) | 192 (46.8) | |
| Current or ever smoking | 152 (36.9) | 120 (29.3) | 0.013 |
| Duration of smoking cessation (years) (Mean ± SD) | 4.8 ± 2.5 | 5.2 ± 2.9 | 0.114 |
| Current or ever alcohol consumption | 171 (42.1) | 140 (34.1) | 0.019 |
| BMI (kg/m2) (Mean ± SD) | 24.3 ± 8.5 | 23.6 ± 9.0 | 0.254 |
| ESR (mm/1st hours) (Mean ± SD) | 35.2 ± 19.46 | 18.9 ± 12.4 | < 0.001 |
| CRP (mg/mL) (Mean ± SD) | 17.6 ± 16.2 | 1.68 ± 6.8 | < 0.001 |
| Family history, N (%) | 170 (41.9) | 0 (0) | |
| RF (IU\ml) (Mean ± SD) | 72.41 ± 32.15 | – | |
| RF positive, N (%) | 340 (83.7) | ||
| Anti-CCP (U/ml) (Mean ± SD) | 147.6 ± 65.7 | – | |
| Anti-CCP positive, N (%) | 304 (74.9) | ||
| Duration of RA (years) (Mean ± SD) | 3.26 ± 0.92 | – | |
| DAS28 score, N (%) | |||
| Low (< 3.2) | 112 (27.6) | – | |
| Intermediate (3.2–5.1) | 160 (39.4) | – | |
| High (> 5.1) | 134 (33.0) | – |
BMI: body mass index; CRP: C-reactive protein; ESR: Erythrocyte Sedimentation Rate; RF: Rheumatoid Factor; Anti CCP: Anti- Cyclic Citrullinated Peptide; DAS 28: disease activity score
In this study, the distribution of four SNP genotypes in the control group were according to HWE (all P values > 0.05). The frequencies of rs2055979 minor allele (A) were significantly higher in RA patients than those in controls (9.8% and 4.4%). Logistic regression analysis showed that the risks of RA were significantly higher in carriers with rs2055979- CA genotype (OR = 1.63, 95% CI = 1.28–1.97), AA genotype (OR = 2.02, 95% CI = 1.47–2.59), AA + CA genotype (OR = 1.78, 95% CI = 1.32–2.26), compared to carriers with CC genotype. In allele genetic model, rs2055979-A was also associated with increased RA risk (OR = 1.72, 95% CI = 1.39–2.06). However, we did not find any significant association of rs2221903, rs907715 and rs12508721 with RA risk (Table 2).
Table 2.
Genotype and allele frequencies of four SNPs between case and control group
| SNP | Genotypes and alleles | Frequencies N (%) | OR (95%CI)* | P-values for HWE test | P-values for OR | |
|---|---|---|---|---|---|---|
| Normal controls (n = 410) |
RA patients (n = 406) |
|||||
| rs2055979 | CC | 270 (65.8) | 205 (50.5) | 1.00 | ||
| CA | 122 (29.8) | 161 (39.7) | 1.63 (1.28–1.97) | 0.0006 | ||
| AA | 18 (4.4) | 40 (9.8) | 2.02 (1.47–2.59) | < 0.001 | ||
| AA + CA | 140 (34.2) | 201 (49.5) | 1.78 (1.32–2.26) | < 0.001 | ||
| C | 662 (80.7) | 571 (70.3) | 1.00 | |||
| A | 158 (19.3) | 241 (29.7) | 1.72 (1.39–2.06) | < 0.001 | ||
| HWE test for controls | 0.378 | |||||
| rs2221903 | TT | 242 (59.0) | 225 (55.4) | 1.00 | ||
| TC | 153 (37.3) | 158 (38.9) | 1.21 (0.81–1.65) | 0.427 | ||
| CC | 15 (3.7) | 23 (5.7) | 1.47 (0.72–2.23) | 0.652 | ||
| TC + CC | 168 (41.0) | 181 (44.6) | 1.26 (0.79–1.77) | 0.604 | ||
| T | 637 (77.7) | 608 (74.9) | 1.00 | |||
| C | 183 (22.3) | 204 (25.1) | 1.26 (0.84–1.77) | 0.531 | ||
| HWE test for controls | 0.122 | |||||
| rs907715 | CC | 236 (57.6) | 216 (53.2) | 1.00 | ||
| CT | 147 (35.8) | 153 (37.7) | 1.36 (0.86–1.90) | 0.486 | ||
| TT | 27 (6.6) | 37 (9.1) | 1.54 (0.78–2.32) | 0.621 | ||
| CT + TT | 174 (42.4) | 190 (46.8) | 1.39 (0.83–2.01) | 0.536 | ||
| C | 619 (75.5) | 585 (72.0) | 1.00 | |||
| T | 201 (24.5) | 227 (28.0) | 1.40 (0.87–1.95) | 0.503 | ||
| HWE test for controls | 0.528 | |||||
| rs12508721 | TT | 246 (60.0) | 226 (55.7) | 1.00 | ||
| TC | 145 (35.4) | 152 (37.4) | 1.40 (0.90–1.92) | 0.284 | ||
| CC | 19 (4.6) | 28 (6.9) | 1.61 (0.84–2.39) | 0.492 | ||
| CT + TT | 164 (40.0) | 180 (44.3) | 1.44 (0.88–2.04) | 0.405 | ||
| T | 637 (77.7) | 604 (74.4) | 1.00 | |||
| C | 183 (22.3) | 208 (25.6) | 1.45 (0.92–2.02) | 0.382 | ||
| HWE test for controls | 0.686 | |||||
*Adjusted for age, gender, smoking status, alcohol drinking status and BMI
GMDR was employed to screen IL-21 gene-environment interactions through combinatorial evaluation of rs2069762, rs2221903, rs13143866 and rs907715 variants with environmental factors (smoking and alcohol drinking) on the RA susceptibility (Table 3). We found a statistically significant two-locus model (P = 0.018), which included rs2055979 and smoking. This indicates that the interaction between rs2055979 and smoking was significantly associated with the risk of RA. The Cross-validation consistency of the two-site model was 10/10 and the test accuracy was 0.632.
Table 3.
GMDR analysis on the best interaction models between IL-21 gene SNPs and smoking and alcohol consumption
| Locus no. | Best combination | Cross-validation consistency | Testing balanced accuracy | p-values* |
|---|---|---|---|---|
| IL-21 gene-smoking interaction* | ||||
| 2 | rs2055979, smoking | 10/10 | 0.632 | 0.018 |
| 3 | rs2055979, rs12508721, smoking | 7/10 | 0.607 | 0.324 |
| 4 | rs2055979, rs12508721, rs2221903, smoking | 6/10 | 0.532 | 0.425 |
| 5 | rs2055979, rs12508721, rs2221903, rs907715, smoking | 8/10 | 0.521 | 0.182 |
| IL-21 gene-alcohol consumption interaction** | ||||
| 2 | rs2055979, alcohol drinking | 8/10 | 0.524 | 0.256 |
| 3 | rs2055979, rs12508721, alcohol drinking | 6/10 | 0.518 | 0.359 |
| 4 | rs2055979, rs12508721, rs2221903, alcohol drinking | 5/10 | 0.532 | 0.746 |
| 5 | rs2055979, rs12508721, rs2221903, rs907715, alcohol drinking | 6/10 | 0.496 | 0.532 |
*Adjusted for age, gender, alcohol drinking status and BMI
**Adjusted for age, gender, smoking status and BMI
To test the effect value of this gene- environment interaction, we performed cross analysis according to smoking status (Never and Current or ever) and rs2055979 genotypes (CC and AA or CA), and participants were grouped into four groups, including never smokers with rs2055979- CC genotype, never smokers with rs2055979- AA or CA genotype, current or ever smokers with rs2055979-CC genotype, current or ever smokers with rs2055979-AA or CA genotype. We found that current or ever smokers with rs2055979-AA or CA genotype had the highest risk of RA, compared with never smokers with rs2055979-CC genotype. After covariates adjustment for age, gender, alcohol drinking status and BMI, the OR (95% CI) was 3.23 (1.86–4.64) (Table 4).
Table 4.
Analysis of interaction between rs2055979 and smoking on RA risk by using logistic regression
| rs2055979 | Smoking | OR (95% CI)* | P-values |
|---|---|---|---|
| CC | Never | 1.00 | – |
| AA + CA | Never | 1.52 (1.13–1.94) | 0.0014 |
| CC | Current or ever | 1.67 (1.21–2.15) | < 0.001 |
| AA + CA | Current or ever | 3.23 (1.86–4.64) | < 0.001 |
| Interaction P- values: 0.041 | |||
*Adjusted for age, gender, alcohol drinking status and BMI
Discussion
This research examined the association between four IL-21 gene SNPs and the risk of RA in a Chinese Han population. We found that rs2055979 minor allele (A) was associated with increased RA risk. However, no statistically significant relationship was found between rs2221903, rs907715, rs12508721 and RA risk. The IL-21 gene, mapped to chromosomal region 4q27, contains five exons in regions within its genomic structure. And all selected SNPs in this study were located in the intron region. Previously, several studies reported that SNPs of IL-21 genes were associated with several autoimmune disorders [14, 15] in different populations. Two meta- analyses [16, 17] also reported that IL-21 gene rs6822844 was significantly associated with RA risk. Contrast to rs6822844, less study focused on rs2055979, rs2221903, rs907715 and rs12508721. A case- control study [26] in Mexican populations suggested that IL-21 gene rs2055979 was associated with increased RA risk, but no significant association was found between rs2221903 and RA risk. Hao et al. [27] performed a case-control study in Chinese populations and suggested that rs2055979 was associated with increased RA risk, individuals with the AA genotype exhibit a significantly increased risk of developing rheumatoid arthritis, with a 4.34 times greater likelihood. However, rs2221903 and rs907715 were not correlated with RA risk. Similarly, in an earlier study, a study [28] demonstrated no significant association with RA susceptibility in the Australian population. Although previous studies have investigated the relationship between rs2055979, rs2221903 and rs907715 in different populations, especially the study in Chinese. In terms of rs12508721, Malinowski et al. [29] concluded that no significant relationship existed between rs2221903 variants and RA susceptibility. Compared to the four fore-mentioned studies, our research has the following advantages: first, the sample size of our study was larger than that of the four fore- mentioned studies. Second, rs12508721 was not investigated in previous studies. So, this SNP (rs12508721) was first investigated on this topic in our study, but we concluded that rs12508721 was not associated with RA risk in this population-based case- control study.
The inflammatory environment in RA is shaped by cytokines that are pivotal to immune dysregulation and aberrant autoantibody synthesis [30, 31]. Among these, IL-21 is centrally involved in regulating immune and non-immune cells, with roles spanning CD4 + T-cell activation and proinflammatory cytokine release to support Th17 development [32]. Genetic analysis [26] revealed that the IL-21 gene rs2055979 AA genotype correlated with elevated anti-CCP antibodies in RA. Mechanistically, IL-21 enhances antibody output by stimulating B-cell clonal-expansion and plasma cell formation; however, a causal relationship between this SNP and antibody overproduction remains speculative [33].
RA susceptibility could be mediated through a multifactorial framework, encompassing hereditary components, environmental influences, and their dynamic interplay. Previously, several studies reported the impact of smoking [18, 19] and alcohol drinking [34] on RA pathology. In this study, we found that the current or ever smoking and alcohol drinking rates were higher in RA patients than in controls, which means that the smoking status may be associated with RA risk. So, we performed gene- environment interaction among four SNPs of IL-21 gene, smoking and alcohol drinking status using GMDR model. We found that the interaction between rs2055979 and smoking was significantly associated with the risk of RA. Previously, several studies reported that other genes may interact with smoking to influence RA susceptibility [35, 36]. This is the first study focused on the impact of IL-21 gene- smoking interaction on RA risk. Therefore, RA susceptibility could be influenced by IL-21 gene SNPs, such as rs2055979, however this impact could be influenced by environmental factors, such as smoking status. The RA risk for smokers with rs2055979 minor allele was higher than the sum of subjects with single risk factors (smoking or rs2055979 minor allele). In the verification of RA risk, we should consider not only the single risk factor, but also the synergetic effect among these factors.
This study also has some limitations to explain. Firstly, some serological markers were not measured, including IL-21 levels, ACPA/RF, therefore, it is difficult to explain the effect of rs2055979 on RA mechanism from physiological indicators or serum markers. Secondly, more SNPs of IL-21 genes and more environmental factors should be enrolled in future studies to verify the results obtained in this study. Thirdly, the sex ratio of RA cases is not in line with the routine, which means that the selection bias may exist in this case- control study. The results obtained in this study need to be verified in different populations. Lastly, DAS28 evaluation was not performed for controls, who were normal control without RA, so we could not perform testing on association between IL-21 gene-smoking interaction and DAS28 score, to strengthen the clinical relevance of the findings.
In summary, our findings reveal that both the A allele at the rs2055979 locus of IL-21 gene, and a gene-environment interaction between rs2055979 and smoking behavior demonstrate significant correlations with elevated RA risk. In the future, more functional studies should be performed to investigate the correlation between rs2055979 genotypes and IL-21 expression or B-cell activity. In addition, more environmental factors, such as pollutants or epigenetics should be included in the gene-environment analyses.
Supplementary Information
Acknowledgements
None.
Abbreviations
- OR
Odds ratios
- CI
Confidence interval
- RA
Rheumatoid arthritis
- IL-21
Interleukin-21
- GMDR
Generalized multifactor dimensionality reduction
- SNPs
Single nucleotide polymorphisms
- HWE
Hardy-Weinberg equilibrium
- BMI
Body mass index
- CRP
C-reactive protein
- ESR
Erythrocyte Sedimentation Rate
- RF
Rheumatoid Factor
- Anti CCP
Anti Cyclic Citrullinated Peptide
Author contributions
All authors have read and approved the manuscript. Xiang Lu: guarantor of integrity of the entire study, study design, literature research, data acquisition, manuscript review; Yuan Xue: study concepts, experimental studies, manuscript editing; Shanle Yan: definition of intellectual content, statistical analysis and manuscript preparation.
Funding
Not applicable.
Data availability
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethical approval and consent to participate
Each participant understood the process of the study and signed a written informed consent before the start of the study. All study protocols of the current study were approved by the ethics committee of the Fourth Affiliated Hospital of Soochow University (2025-251185). All methods were performed in accordance with the Declaration of Helsinki.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- 1.Zordan P, Rigamonti E, Freudenberg K, Conti V, Azzoni E, Rovere-Querini P, Brunelli S. Macrophages commit postnatal endothelium-derived progenitors to angiogenesis and restrict endothelial to mesenchymal transition during muscle regeneration. Cell Death Dis. 2014;5:e1031. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.McInnes IB, Schett G. The pathogenesis of rheumatoid arthritis. N Engl J Med. 2011;365:2205–19. [DOI] [PubMed] [Google Scholar]
- 3.Loewer S, Cabili MN, Guttman M, Loh YH, Thomas K, Park IH, Garber M, Curran M, Onder T, Agarwal S, Manos PD, Datta S, Lander ES, Schlaeger TM, Daley GQ, Rinn JL. Large intergenic non-coding RNA-RoR modulates reprogramming of human induced pluripotent stem cells. Nat Genet. 2010;42:1113–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Yang L, Lin C, Liu W, Zhang J, Ohgi KA, Grinstein JD, Dorrestein PC, Rosenfeld MG. Ncrna- and Pc2 methylation-dependent gene relocation between nuclear structures mediates gene activation programs. Cell. 2011;147:773–88. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Cross M, Smith E, Hoy D, Carmona L, Wolfe F, Vos T, Williams B, Gabriel S, Lassere M, Johns N, Buchbinder R, Woolf A, March L. The global burden of rheumatoid arthritis: estimates from the global burden of disease 2010 study. Ann Rheum Dis. 2014;73:1316–22. [DOI] [PubMed] [Google Scholar]
- 6.Kurkó J, Besenyei T, Laki J, Glant TT, Mikecz K, Szekanecz Z. Genetics of rheumatoid arthritis - a comprehensive review. Clin Rev Allergy Immunol. 2013;45:170–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Deane KD, Demoruelle MK, Kelmenson LB, Kuhn KA, Norris JM, Holers VM. Genetic and environmental risk factors for rheumatoid arthritis. Best Pract Res Clin Rheumatol. 2017;31:3–18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Long D, Chen Y, Wu H, Zhao M, Lu Q. Clinical significance and immunobiology of IL-21 in autoimmunity. J Autoimmun. 2019;99:1–14. [DOI] [PubMed] [Google Scholar]
- 9.Leonard WJ, Spolski R. Interleukin-21: a modulator of lymphoid proliferation, apoptosis and differentiation. Nat Rev Immunol. 2005;5:688–98. [DOI] [PubMed] [Google Scholar]
- 10.Varricchi G, Harker J, Borriello F, Marone G, Durham SR, Shamji MH. T follicular helper (Tfh) cells in normal immune responses and in allergic disorders. Allergy. 2016;71(8):1086–94. [DOI] [PubMed] [Google Scholar]
- 11.Kwok SK, Cho ML, Park MK, Oh HJ, Park JS, Her YM, Lee SY, Youn J, Ju JH, Park KS, Kim SI, Kim HY, Park SH. Interleukin-21 promotes osteoclastogenesis in humans with rheumatoid arthritis and in mice with collagen-induced arthritis. Arthritis Rheum. 2012;64:740–51. [DOI] [PubMed] [Google Scholar]
- 12.Xing R, Jin Y, Sun L, Yang L, Li C, Li Z, Liu X, Zhao J. Interleukin-21 induces migration and invasion of fibroblast-like synoviocytes from patients with rheumatoid arthritis. Clin Exp Immunol. 2016;184:147–58. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Xing R, Yang L, Jin Y, Sun L, Li C, Li Z, Zhao J, Liu X. Interleukin-21 induces proliferation and proinflammatory cytokine profile of fibroblast-like synoviocytes of patients with rheumatoid arthritis. Scand J Immunol. 2016;83:64–71. [DOI] [PubMed] [Google Scholar]
- 14.Lan Y, Luo B, Wang JL, Jiang YW, Wei YS. The association of interleukin-21 polymorphisms with interleukin-21 serum levels and risk of systemic lupus erythematosus. Gene. 2014;538:94–8. [DOI] [PubMed] [Google Scholar]
- 15.Espinoza-García N, Salazar-Camarena DC, Marín-Rosales M, Reyes-Mata MP, Ramírez-Dueñas MG, Muñoz-Valle JF, Borunda-Calderón IM, González-Palacios A, Palafox-Sánchez CA. High interleukin 21 levels in patients with systemic lupus erythematosus: association with clinical variables and rs2221903 polymorphism. J Clin Med. 2024;13: 4512. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Agonia I, Couras J, Cunha A, Andrade AJ, Macedo J, Sousa-Pinto B. IL-17, IL-21 and IL-22 polymorphisms in rheumatoid arthritis: a systematic review and meta-analysis. Cytokine. 2020;125:154813. [DOI] [PubMed] [Google Scholar]
- 17.Ren K, Tang J, Nong L, Shen N, Li X. Association between interleukin-21 gene rs6822844 polymorphism and rheumatoid arthritis susceptibility. Biosci Rep. 2019;39: BSR20190110. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Ishikawa Y, Terao C. The impact of cigarette smoking on risk of rheumatoid arthritis: a narrative review. Cells. 2020;9:475. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Zhang X, Zhang X, Yang Y, Zhi K, Chen Y, Zhao J, Cui W, Zhao X, Zhang Z, An Y, Cao W. Association between passive smoking and the risk of rheumatoid arthritis: a systematic review and meta-analysis. Clin Rheumatol. 2023;42:663–72. [DOI] [PubMed] [Google Scholar]
- 20.Liu X, Mai H, Wang L, Zhang H, Li X, Li X, Wang L. IL-4 polymorphisms (rs2227284, rs2243267, and rs2243270) are associated with reduced risk of rheumatoid arthritis. Autoimmunity. 2024;57: 2364684. [DOI] [PubMed] [Google Scholar]
- 21.Bashir M, Mateen W, Khurshid S, Mehmood Malik J, Agha Z, Khan F, Ajmal M, Ali SHB. A common missense variant rs874881 of PADI4 gene and rheumatoid arthritis: genetic association study and in-silico analysis. Gene. 2023;854:147123. [DOI] [PubMed] [Google Scholar]
- 22.Aletaha D, Neogi T, Silman AJ, Funovits J, Felson DT, Bingham CO 3rd, Birnbaum NS, Burmester GR, Bykerk VP, Cohen MD, Combe B, Costenbader KH, Dougados M, Emery P, Ferraccioli G, Hazes JM, Hobbs K, Huizinga TW, Kavanaugh A, Kay J, Kvien TK, Laing T, Mease P, Ménard HA, Moreland LW, Naden RL, Pincus T, Smolen JS, Stanislawska-Biernat E, Symmons D, Tak PP, Upchurch KS, Vencovsky J, Wolfe F, Hawker G. 2010 rheumatoid arthritis classification criteria: an American college of rheumatology/European league against rheumatism collaborative initiative. Ann Rheum Dis. 2010;69:1580–8. [DOI] [PubMed] [Google Scholar]
- 23.Ryan TP. Sample size determination and power. Hoboken, New Jersey: Wiley; 2013. [Google Scholar]
- 24.Luo WS, Chen F, Ji JM, Guo ZR. Interaction of tobacco smoking and alcohol consumption with obesity on cardiovascular disease in a Chinese cohort. Coron Artery Dis. 2020;31(4):372–7. [DOI] [PubMed] [Google Scholar]
- 25.Xu HM, Xu LF, Hou TT, Luo LF, Chen GB, Sun XW, Lou XY. GMDR: versatile software for detecting gene-gene and gene-environment interactions underlying complex traits. Curr Genomics. 2016;17:396–402. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Carreño-Saavedra NM, Reyes-Pérez IV, Machado-Sulbaran AC, Martínez-Bonilla GE, Ramírez-Dueñas MG, Muñoz-Valle JF, Olaya-Valdiviezo V, García-Iglesias T, Martínez-García EA, Sánchez-Hernández PE. IL-21 (rs2055979 and rs2221903)/IL-21R (rs3093301) polymorphism and high levels of IL-21 are associated with rheumatoid arthritis in Mexican patients. Genes. 2023. 10.3390/genes14040878. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Hao Y, Xie L, Xia J, Liu Z, Yang B, Zhang M. Plasma interleukin-21 levels and genetic variants are associated with susceptibility to rheumatoid arthritis. BMC Musculoskelet Disord. 2021;22:246. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Hollis-Moffatt JE, Chen-Xu M, Topless R, Dalbeth N, Gow PJ, Harrison AA, Highton J, Jones PB, Nissen M, Smith MD, et al. Only one independent genetic association with rheumatoid arthritis within the KIAA1109-TENR-IL2-IL21 locus in Caucasian sample sets: confirmation of association ofrs6822844 with rheumatoid arthritis at a genome-wide level of significance. Arthritis Res Ther. 2010;12:R116. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Malinowski D, Paradowska-Gorycka A, Safranow K, Pawlik A. Interleukin-21 gene polymorphism rs2221903 is associated with disease activity in patients with rheumatoid arthritis. Arch Med Sci. 2017;13:1142–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Gharibi T, Majidi J, Kazemi T, Dehghanzadeh R, Motallebnezhad M, Babaloo Z. Biological effects of IL-21 on different immune cells and its role in autoimmune diseases. Immunobiology. 2016;221:357–67. [DOI] [PubMed] [Google Scholar]
- 31.Scherer HU, Huizinga TWJ, Krönke G, Schett G, Toes REM. The B cell response to citrullinated antigens in the development of rheumatoid arthritis. Nat Rev Rheumatol. 2018;14:157–69. [DOI] [PubMed] [Google Scholar]
- 32.Niu X, He D, Zhang X, Yue T, Li N, Zhang JZ, Dong C, Chen G. IL-21 regulates Th17 cells in rheumatoid arthritis. Hum Immunol. 2010;71:334–41. [DOI] [PubMed] [Google Scholar]
- 33.Wu Y, van Besouw NM, Shi Y, Hoogduijn MJ, Wang L, Baan CC. The biological effects of IL-21 signaling on B-cell-mediated responses in organ transplantation. Front Immunol. 2016;7:319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Yang X, Long X, Xiao P, Ge Q, Zhang L, Wang X. Analysis of data from the NHANES 1999–2018 and Mendelian randomization studies reveals the relationship between alcohol use and rheumatoid arthritis. Nutr J. 2024;23:156. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Meng W, Zhu Z, Jiang X, Too CL, Uebe S, Jagodic M, Kockum I, Murad S, Ferrucci L, Alfredsson L, Zou H, Klareskog L, Feinberg AP, Ekström TJ, Padyukov L, Liu Y. DNA methylation mediates genotype and smoking interaction in the development of anti-citrullinated peptide antibody-positive rheumatoid arthritis. Arthritis Res Ther. 2017;19(1):71. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Jiang X, Källberg H, Chen Z, Ärlestig L, Rantapää-Dahlqvist S, Davila S, Klareskog L, Padyukov L, Alfredsson L. An immunochip-based interaction study of contrasting interaction effects with smoking in ACPA-positive versus ACPA-negative rheumatoid arthritis. Rheumatology (Oxford). 2016;55(1):149–55. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.