Impact of Smoking on Adalimumab Response and Biomarkers in Rheumatoid Arthritis

Dampak Merokok terhadap Respons Adalimumab dan Biomarker pada Pasien Artritis Reumatoid

Ghasaq Kareem Abed¹, MSc Student; Prof. Dr. Asma Abdul Jaleel Swadi², MBChB, PhD (Supervisor)

¹ Maternity and Pediatrics Teaching Hospital, Al-Qadisiyah Health Office, Al-Qadisiyah, Iraq.

² College of Medicine, University of Al-Qadisiyah, Al-Diwaniyah Province, Iraq.

Corresponding Author: Ghasaq Kareem Abed

Emails: med.post25.43@qu.edu.iq; asma.althuwaynee@qu.edu.iq;

Phone: 07805223404, 07713026190

Abstract

Rheumatoid arthritis (RA) is a chronic autoimmune disorder marked by ongoing joint inflammation that results in progressive destruction of cartilage and bone, as well as functional impairment. Adalimumab, a tumor necrosis factor-alpha (TNF-α) inhibitor, is commonly used for moderate-to-severe RA; however, a significant number of patients do not achieve a sufficient clinical response.

Smoking has been suggested as a potential factor influencing treatment outcomes, although its combined effect on inflammatory and structural biomarkers remains unclear.

This study aimed to evaluate whether smoking status is associated with inadequate clinical response and elevated serum levels of TNF-α, interleukin-6 (IL-6), and matrix metalloproteinase-3 (MMP-3) in RA patients receiving adalimumab monotherapy.

A cross-sectional investigation included 75 rheumatoid arthritis patients and 55 healthy controls. Patients stayed classified into responders and non-responders rendering to EULAR criteria. Serum levels of TNF-α, IL-6, and MMP-3 were measured using ELISA.

Smoking prevalence was significantly higher among non-responders compared to responders (p = 0.004). Non-responders showed significantly elevated levels of TNF-α, IL-6, and MMP-3 (p < 0.001). Smoking demonstrated significant positive correlations with TNF-α (r = 0.440), IL-6 (r = 0.445), and MMP-3 (r = 0.354).

These findings suggest that smoking is associated with reduced therapeutic response and increased inflammatory and tissue-destructive activity. MMP-3 may serve as a useful biomarker for treatment response. Smoking cessation may improve clinical outcomes in rheumatoid arthritis patients receiving adalimumab.

Keywords: Rheumatoid Arthritis, Adalimumab, Smoking, TNF-α, IL-6, MMP-3

Abstrak

Latar Belakang: Artritis reumatoid adalah penyakit autoimun kronis yang ditandai dengan peradangan sendi yang persisten. Adalimumab, sebuah penghambat tumor necrosis factor-alpha (TNF-α), banyak digunakan untuk terapi, namun banyak pasien gagal mencapai respons klinis yang memadai. Merokok dianggap sebagai faktor potensial yang mempengaruhi hasil pengobatan.

Tujuan: Penelitian ini bertujuan untuk mengevaluasi apakah status merokok berhubungan dengan respons klinis yang tidak memadai dan peningkatan kadar serum TNF-α, interleukin-6 (IL-6), dan matrix metalloproteinase-3 (MMP-3) pada pasien artritis reumatoid yang menerima monoterapi adalimumab.

Metode: Studi potong lintang ini melibatkan 75 pasien artritis reumatoid dan 55 kontrol sehat. Pasien diklasifikasikan menjadi kelompok respons (responders) dan non-respons (non-responders) berdasarkan kriteria EULAR. Kadar serum TNF-α, IL-6, dan MMP-3 diukur menggunakan metode ELISA.

Hasil: Prevalensi merokok secara signifikan lebih tinggi pada kelompok non-respons dibandingkan kelompok respons (p = 0,004). Kelompok non-respons menunjukkan peningkatan kadar TNF-α, IL-6, dan MMP-3 yang signifikan (p < 0,001). Merokok menunjukkan korelasi positif yang signifikan dengan TNF-α (r = 0,440), IL-6 (r = 0,445), dan MMP-3 (r = 0,354).

Kesimpulan: Temuan ini menunjukkan bahwa merokok berhubungan dengan penurunan respons terapeutik dan peningkatan aktivitas peradangan serta kerusakan jaringan. MMP-3 dapat berfungsi sebagai biomarker yang berguna untuk memantau respons pengobatan. Berhenti merokok dapat meningkatkan hasil klinis pada pasien artritis reumatoid yang menerima adalimumab.

Kata Kunci: Artritis Reumatoid, Adalimumab, Merokok, TNF-α, IL-6, MMP-3

Introduction

Rheumatoid arthritis is a chronic, systemic autoimmune disorder considered by ongoing synovial inflammation, progressive damage to cartilage, and joint deformities, resulting in considerable functional impairment. It affects about 1% of the worldwide population and is linked to significant morbidity and a decreased quality of life.

1.

The pathogenesis of rheumatoid arthritis is driven by a complex network of pro-inflammatory cytokines, particularly tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), which regulate immune activation, synovial proliferation, and joint destruction. IL-6 contributes to persistence of inflammation and disease progression2.

Adalimumab, a monoclonal antibody that targets TNF-α, is a key therapy for moderate-to-severe RA. It has shown substantial effectiveness in lowering disease activity, enhancing physical function, and preventing structural joint damage. However, a notable proportion of patients do not attain an adequate clinical response, underscoring the importance of identifying predictors of management results3.

Smoking has emerged as an important environmental factor influencing disease severity and therapeutic response. It has been related with augmented systemic inflammatory action and elevated levels of inflammatory markers, which may contribute to disease progression4. In addition, smoking has been revealed to reduce the clinical response to anti-TNF therapy in patients with RA , leading to poorer treatment outcomes and lower rates of clinical improvement 5.

Matrix metalloproteinase-3 (MMP-3) is an enzyme involved in extracellular matrix degradation and cartilage destruction. Elevated levels of MMP-3 reflect synovial inflammation and structural joint damage, and it has been proposed as a useful biomarker for disease activity and treatment response 67

Despite available evidence, the combined effect of smoking on TNF-α, IL-6, and MMP-3 in patients treated with adalimumab remains insufficiently studied. Therefore, this study investigates the relationship between smoking, inflammatory biomarkers, and treatment response.

METHODS

S tudy design and participants

This cross-sectional study included 130 participants: 75 RA patients satisfying the 2010 ACR/EULAR principles and 55 well controls. All RA sick stood treated with adalimumab monotherapy (40 mg subcutaneously every 2 weeks) for at least 6 months.

Patients were classified into:

•Responders (n = 35): DAS28 < 2.6 or improvement ≥ 1.2

•Non-responders (n = 40): DAS28 ≥ 2.6 and improvement < 1.2

Exclusion criteria

Use of any other biologic agent, acute infection or malignancy and pregnancy or lactation.

Data collection

Demographic and clinical data included age, sex, smoking status (current smokers vs non-smokers), disease duration, DAS28 score, and concomitant NSAID or steroid use.

Measurement of BiomarkersBlood specimens were obtained. Serum concentrations of MMP-3, interleukin-6 (IL-6), in addition tumor necrosis factor-alpha (TNF-α) stood enumerated utilizing commercial ELISA kits in accordance with the manufacturer's guidelines. All assays were conducted in duplicate.

Statistical analysis

Information stood investigated by SPSS version 23. Continuous variables were expressed as mean ± SD and definite variables as number (%). Chi-square, independent t-test, ANOVA, and Pearson correlation were applied. P ≤ 0.05 was considered significant.

Results and Discussion

1. General characteristics compared among study groups

General characteristics compared among study groups are shown in table 1. Comparison of mean age revealed no significant difference (p = 0.603). There was also no significant difference in proportions of males and females between groups (p = 0.870).

Smoking rate was higher in a significant manner in failure group in comparison with response group, 32.5 % versus 5.7 %, respectively (p = 0.004).

Table 1. General characteristics compared among study groups

S: significant; N: not significant

2. Comparison of TNF-a mean levels among study groups

Comparison of TNF-a mean levels among study groups is shown in table 2. This comparison revealed significant difference (p < 0.001). The level was significantly highest in failure group (48.98 ±8.27) followed by response group (42.32 ±6.21) then by control group (37.19 ±9.61).

Table 2 Comparison of TNF-a mean levels among study groups

TNF-a: SD: standard deviation; S: significant; small letters (a, b and c) were used to show the results of post-hoc LSD multiple comparison test so that letter a takings the uppermost rate surveyed by letter b then letter c; like letters indicated no important variation; whereas, different letters indicated important alteration

3 . Comparison of IL-6 mean levels among study groups

Comparison of IL-6 mean levels among study groups is shown in table 3. This comparison revealed significant difference (p < 0.001). The level was significantly highest in failure group (21.86 ±10.91) followed by response group (17.73 ±6.97) then by control group (14.40 ±3.92).

Table 3: Comparison of IL-6 mean levels among study groups

IL-6: interleukin; SD: standard deviation; S: significant; small letters (a, b and c) were used to show the results of post-hoc LSD multiple comparison test so that letter a takings the uppermost rate surveyed by letter b then letter c; like letters indicated no important variation; whereas, different letters indicated important alteration

4 . Comparison of MMP3 mean levels among study groups

Comparison of matrix metalloproteinase 3 (MMP3) mean levels among study groups is shown in table 4. This comparison revealed significant difference (p < 0.001). The level was significantly highest in failure group (41.65 ±5.94) followed by response group (35.2 ±5.66) then by control group (30.82 ±2.73).

Table 4: Comparison of MMP3 mean levels among study groups

MMP3: matrix metalloproteinase 3; SD: standard deviation; S: significant; small letters (a, b and c) were used to show the results of post-hoc LSD multiple comparison test so that letter a takings the uppermost rate surveyed by letter b then letter c; like letters indicated no important variation; whereas, different letters indicated important alteration

Correlation study

Immune markers correlations to smoking are demonstrated in table 5. All markers showed significant and positive correlations to smoking.

Table 5: Immune marker correlations to smoking

S: significant

In the current study observation smoking rate was significantly higher among the failure group compared to the response group. Therefore, it can be proposed that the response of RA patients to ADA is greatly affected by smoking. In line with current observation, poor response to treatment has been reported and was found to be related with the strength of preceding smoking, regardless of smoking grade at start of anti-TNF therapy8.

Moreover, smoking was found to be a prognostic of poor response to anti-TNF management for up to 12 months, and heavy smokers had the poorest treatment persistence9. Similarly, smoking is a poor predictor of responsiveness to anti-TNF therapy in RA and smoking at the time of anti-TNF initiation decreased the likelihood of obtaining at least a moderate EULAR response via 80%510 11 .

Contrary to our findings, some studies found no difference in response to anti-TNF treatment in RA between smokers and non-smokers. However, they emphasized that prospective controlled studies involving tobacco exposure are necessary to better define the response to anti-TNF-α agents 12 .

The reason why smokers react less well to anti-TNF therapy is unknown. Anti-rheumatic medication bioavailability may be impacted by smoking. Additionally, smoking may be associated with behavioral and socioeconomic factors that could potentially influence treatment outcomes 13.

In this study, comparison of TNF-a mean levels among study groups revealed that the level stayed meaningfully highest in the failure groping followed by the response groping then by the control group. Therefore, it is a reliable marker for treatment response. Its high level in failure group may indicate the existence of continuing inflammatory state attributed to smoking.

It has been shown that adalimumab treatment can restore TNFα levels in RA patients to those of healthy control subjects, which is consistent with the findings of the current investigation.14

Similarly, IL-6 levels were significantly higher in the failure group followed by response group then by control group. Thus, we can consider IL-6 as a relatable marker for evaluation of treatment response. Its high level in failure group may indicate the existence of continuing inflammatory state attributed to smoking.

Since the pathophysiology of RA involves a network of cytokines, blocking one cytokine, like TNF-α, may have an impact on other cytokines, particularly IL-6, which is one of the most frequently expressed cytokines in RA patients and has overlapping effects with TNF-α 15.

Matrix metalloproteinases (MMPs) are a large group of zinc-dependent proteases capable of degrading extracellular matrix components such as collagen, gelatin, elastin, and casein. MMP-3, a member of this family, is formed within joints and contributes to the progression of inflammation by cleaving extracellular matrix elements, including collagen types III, IX, and X, as well as the telopeptides of collagen types I, II, and XI, and by activating several pro-MMPs, comprising pro-MMP-1, pro-MMP-7, pro-MMP-8, pro-MMP-9, and pro-MMP-13.7.

In our study, the level of MMP3 was significantly highest in failure group followed by response group then by control group indicating that this marker is a good indicator of response to treatment with anti-TNF agents. Our results are supported by previous studies showing that enhancement in serum MMP-3 ranks at 4 weeks after beginning of ADA treatment can predict decrease at 52 weeks in RA sick7.

Thus, serum measurement of MMP3 is an effective indicator of response of RA patients treated by ADA and that estimation of baseline levels in such patients may prove to be necessary before initiation of therapy. The higher level of such marker in failure group may be related to resistance to treatment created by persistent systemic inflammation attributed to smoking .

Additionally, Smoking showed significant positive correlation with interleukin-6 (IL-6), TNF, levels. This supports the hypothesis that smoking contributes to a heightened inflammatory state, which may reduce the effectiveness of anti-TNF therapy 4.

Conclusions

Smoking is linked to poor response to Adalimumab in RA, with higher TNF-alpha, Interleukin-6, and Matrix Metalloproteinase-3 levels indicating persistent inflammation and joint damage.

Acknowledgments

The authors thank all study participants for their cooperation.

Funders

No money was established for this training.

Conflict of Attention Statements

The authors declare no struggle of attention.

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