Impact of Three Anti-TNFα Biologics on Existing and Emergent Autoimmunity in Rheumatoid Arthritis and Spondylarthropathy Patients
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- Bacquet-Deschryver, H., Jouen, F., Quillard, M. et al. J Clin Immunol (2008) 28: 445. doi:10.1007/s10875-008-9214-3
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The objective of this study was to analyze the effects of 3 anti-TNFα agents on markers of autoimmunity in rheumatoid arthritis (RA) and spondylarthropathy (SPA) patients.
First-time anti-TNFα biologics (infliximab, etanercept, or adalimumab) were prescribed to 156 RA and 95 SPA (58 ankylosing spondylarthritides, 37 psoriatic arthritides). During 1–2 years of follow-up, clinical, biological [antinuclear (ANA) and anti-double-stranded (dsDNA) antibodies, rheumatoid factors (RF), and anti-cyclic citrullinated peptide (CCP) for RA], and therapeutic data were collected biannually.
ANA appeared or ANA and anti-dsDNA titers increased significantly (P < 0.001) more under infliximab than etanercept in both rheumatisms and than adalimumab in RA patients. During the 2-year follow-up, ANA appeared more in RA patients taking adalimumab than etanercept (P = 0.003), but independently of the anti-TNFα used; anti-dsDNA titers rarely became positive. Under etanercept or infliximab, ANA and anti-dsDNA were not influenced by the underlying pathology nor were they affected by infliximab intensification over 18 months. Only one case of cutaneous lupus was observed in a patient having IgG anti-dsDNA. The therapeutic responses were independent of ANA and anti-dsDNA titers for all rheumatisms and biologics. In RA patients, RF titers, but not anti-CCP levels, declined with the therapeutic response for all biologics.
This is the first study that has evaluated the impact of three TNFα blockers on ANA and anti-dsDNA antibodies in RA and SPA patients. Autoimmunity was more induced with infliximab than etanercept and to a lesser degree to adalimumab but, more importantly, this emergent autoimmunity was exceptionally associated to clinical manifestations of lupus.
KeywordsAntinuclear antibodiestumor necrosis factors alpha blockersanti-CCP (anti-cyclic citrullinated peptide antibodies)rheumatoid arthritisspondylarthropathy
anti-cyclic citrullinated peptide
tumor necrosis factor alpha
- Anti-ds DNA
- DAS 28
disease activity score 28
American College of Rheumatology
Bath ankylosing spondylitis disease activity index
Bath ankylosing spondylitis functional index
erythrocyte sedimentation rate
human anti-chimeric antibodies
Rheumatoid arthritis (RA) and spondylarthropathies (SPA), including both ankylosing spondylitis and psoriatic arthritis, are the most common chronic inflammatory rheumatisms. Their prevalence is estimated at 0.3% in developed nations . Approximately 10–15% of the patients have active and progressive disease refractory to conventional therapies and require tumor necrosis factor-alpha (TNFα) blockers at some time during the course of their disease.
At present, three such agents are available: infliximab, etanercept, and adalimumab. These biologics have demonstrated efficacy against RA clinical activity and structural involvement [2–6], and SPA, be it ankylosing spondylarthritis [7–9] or psoriatic arthritis [10–12]. While SPA are predominantly inflammatory pathologies not associated with the presence of autoantibodies (autoAb), RA is an inflammatory and autoimmune rheumatism associated with numerous autoAb. To diagnose RA, 2 autoAb are routinely sought: rheumatoid factors (RF) and anti-cyclic citrullinated peptide (CCP). The presence of both leads to RA diagnosis for >99% of the patients . Among the autoAb, anti-nuclear antibodies (ANA) are detected in 30% of RA patients, with a titer ≥1/80 being considered positive but are not usually seen at meaningful titers in SPA; anti-double-stranded DNA (anti-dsDNA) are rarely detected in these pathologies, and their positivity should evoke the diagnosis of systemic lupus erythematosus. ANA positivity usually orients the diagnosis toward a connective tissue disease, but their appearance can also be induced by certain factors, including certain chronic infections (notably viral), some lymphoproliferative B cell syndromes, toxic agents, and some medications .
Among the latter, TNFα blockers can be implicated. However, the effect of TNFα blockers on the autoAb associated with RA has not been clearly established because of conflicting results; infliximab is the agent that has been most studied, followed by etanercept and adalimumab [15–24]. This induced autoimmunity was observed in pivotal studies with the three agents [2, 5, 6] but seemed more pronounced with infliximab, but it must be kept in mind that the majority of investigations were conducted with this molecule. Those observational studies evaluated the frequencies of different autoAb, mainly ANA, and their specificities, along with anti-phospholipid, antineutrophil cytoplasm (ANCA), and other autoAb routinely associated with organ-specific autoimmune diseases in long-standing RA or SPA (durations >10 years), with disease resistant to conventional therapies necessitating an anti-TNFα, usually in combination with methotrexate (MTX). Patients had been carefully selected, either SPA, which is not usually associated with ANA production (15% versus 30–50% in RA), or control RA patients treated with MTX alone . This approach enabled the incrimination of the TNFα blocker in the emergence of autoimmunity and to exclude the responsibility of the underlying disease and/or combined therapeutic agents [15, 16, 23, 25–27]. Several trials on SPA or RA compared autoAb appearance under infliximab or etanercept and found it significant only under infliximab [28–30].
To the best of our knowledge, no reported study has simultaneously analyzed the impact of these three anti-TNFα biologics on ANA emergence and RF and anti-CCP autoAb. The overall aim of this study was to analyze retrospectively the effects of the three biotherapies on the autoAb usually associated with RA and their roles in the appearance of ANA in RA and SPA patients followed in our hospital whose inflammatory rheumatisms were TNFα-blocker-naïve and refractory to the molecule that had been prescribed for at least 1 year. The specific objectives were: (1) to compare the impact of the type of TNFα blocker on the induction of ANA; (2) to evaluate the influence of the rheumatism on ANA induction according to the biologic; (3) in RA patients, to assess the effect of the TNFα blocker dose combined with an immunosuppressant and/or corticosteroids on ANA induction; 4) to investigate the relationship between ANA appearance and/or titer and the therapeutic response; and (5) to determine the impact of these TNFα blockers on the titers of RA-specific RF and anti-CCP autoAb and to look for a potential titer–therapeutic response relationship.
Materials and Methods
Two hundred and fifty-one patients with chronic inflammatory rheumatisms followed in our Department of Rheumatology (since at most 2003 or at least 2005) requiring first-time prescription of a TNFα blocker were included in this retrospective study: 156 with active RA [119 women, 37 men; disease activity score 28 (DAS28) >5.1] satisfied the American College of Rheumatology (ACR) classification criteria  and 95 with active SPA [52 women, 43 men; Bath ankylosing spondylitis disease activity index (BASDAI) >40 and DAS28 for those with peripheral involvement]. SPA patients comprised 58 with ankylosing spondylarthritis and 37 with psoriatic arthritis. Ankylosing spondylitis satisfied the New York criteria  and psoriatic arthritis defined according to the Moll and Wright criteria . Patients were seen biannually when we recorded clinical data, disease activity, functional, and biological repercussions. Only the medical files of biotherapy-naïve patients, who had received the same treatment for at least 1 year and for whom the results of at least three specimens collected at 6-month intervals were available, were retained for this analysis.
Among RA patients, 73 were treated with infliximab (73 for 6 months, 71 for 1 year, 63 for 18 months, and 57 for 2 years), 53 were prescribed etanercept (53 for 1 year, 37 for 18 months, and 24 for 2 years), and 30 received adalimumab (30 for 6 months, 28 for 1 year, 20 for 18 months, and 11 for 2 years). Among SPA patients, 53 were treated with infliximab (53 for 1 year, 44 for 18 months, and 33 for 2 years), 39 were prescribed etanercept (39 for 1 year, 16 for 18 months, and 10 for 2 years), and three received adalimumab (3 for 1 year and one for 18 months).
Because some biological data were missing, when possible, some assays were run on serum samples stored in the Rheumatology Department’s or the Clinical and Experimental Immunopathology Laboratory’s serum library. However, several could not be retrieved for RA patients: ten treated with infliximab, eight given etanercept, and three prescribed adalimumab.
Follow-Up Parameters Monitored
Follow-up lasted 1–2 years. At each consultation, the following information were recorded: clinical findings, disease activity (DAS28 for RA and SPA patients with peripheral involvement; BASDAI for SPA with axial involvement), functional repercussions [health assessment questionnaire (HAQ) for RA and SPA patients with peripheral involvement; Bath ankylosing spondylitis functional index (BASFI) for SPA with axial involvement], laboratory test results [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), ANA, anti-dsDNA, latex/Waaler–Rose RF detection, and anti-CCP autoAb for RA patients], and therapeutic interventions (modification or not of the TNFα blocker dose, combined therapies). The response to treatment was also evaluated every 6 months; RA responders were defined by DAS28 improvement >1.2 (compared to entry value), and SPA responders were defined by >50% improvement of their BASDAI scores (compared to entry value). Although DAS28 is not validated in SPA, this index was used for the evaluation of the peripheral involvement because it is easily implemented in clinical practice.
Patients’ sera were collected before starting treatment and then every 6 months. Tests to detect autoAb were run every 6 months with T0 before treatment and T1, T2, T3, and T4 after 6, 12, 18, and 24 months of TNFα-blocker therapy, respectively. Anti-CCP autoAb titers were assessed with a second-generation anti-CCP 2 enzyme-linked immunosorbent assay (ELISA) kit (IgG; Euroimmun, Bioadvance, Lübeck, Germany) with plates read by the automated ELISA EVOLIS system; the positivity threshold is 5 arbitrary units (AU)/ml. ANA were detected by indirect immunofluorescence assay on Hep2 cells transfected with the 60-kDa RO/SSA antigen (Immunoconcept, BMD, Sacramento, CA, USA); the detection threshold is 1/160. IgG anti-dsDNA were sought with the ELISA-DNA kit (Phadia, Freiburg, Germany) using the automated UNICAP-100 system (Phadia); the positivity threshold is 20 IU/ml. Positivity of anti-dsDNA was checked by a second method, the Farr’s test whose threshold of positivity is 4.5 IU/ml. Anti-dsDNA of IgM isotype were not detected, since only those of IgG class are associated with the occurrence of clinical manifestations usually suggestive of systemic lupus erythematosus . To assess RF, the latex test used the Dade–Behring nephelometric technique with “N latex RF” cassettes read on a BN II analyzer (Dade–Behring, Paris La Défense, France), and the Waaler–Rose reaction was measured by an indirect hemagglutination technique (or passive hemagglutination) using “Polyarthritis” cassettes (Fumouze, Levallois-Perret, France); their respective positivity thresholds were 20 and 8 IU/ml.
For qualitative variables (sex, marker positivity), Fisher’s exact test was used because of small number patients/group. Because distributions of quantitative variables were markedly asymmetrical, comparisons were made using the non-parametric Mann–Whitney test (two groups) or the Kruskal–Wallis test (more than two groups), followed by 2 × 2 comparison tests (using Bonferroni’s correction because of the multiple comparisons).
The adalimumab-treated SPA subgroup could not be analyzed statistically because only three patients constituted this group. Frequencies of autoAb induction or comparisons of titers and their variations were evaluated at T3, which corresponds to the time with the largest number of available data with sufficient follow-up.
Results are expressed as medians (range), because of the non-Gaussian distribution of the parameters, or as n (%). A value of P < 0.05 was considered significant.
Characteristics of the RA and SPA Patients Before Starting TNFα Blocker Therapy
Demographic, Clinical, Biological, Immunological, and Treatment Characteristics of the RA and SPA Patients before Onset of Anti-TNFα Biotherapy
RA (n = 156)
SPA (n = 95)
M/F sex ratio
Disease duration (year)
Health assessment questionnaire
ESR (mm/first hour)
ANA (n, %)
Titer [median (range)]
Titer [median (range)]
α-Blocker or salazopyrin
Induction factor (n, %)
Associated Sjögren’s syndromeb
MTX [% mg−1 week−1 (range)]
Leflunomide [% mg−1 day−1 (range)]
Corticosteroids [% mg−1 day−1c (range)]
ANA were sought for each patient before starting TNFα blocker therapy. The positivity threshold was 1/160. The sera of ANA-positive patients were tested for anti-dsDNA autoAb, and we looked for a preexisting induction factor that could explain their presence before the onset of anti-TNFα (salazopyrin, α-blocker, another concomitant autoimmune disease, e.g., Sjögren’s syndrome in this setting). Two RA patients had hepatitis C, without ANA.
Impact of the Type of TNFα Blocker on the Induction of ANA and Anti-dsDNA AutoAb in RA and SPA Patients
For each disease, we compared the effects of the three TNFα blockers on the appearance of ANA for the entire population and then only for patients ANA-negative before starting biotherapy. This analysis enabled comparison of the ANA induction rate under each biologic without the interference of another factor susceptible of generating ANA (e.g., a prior treatment…). First, the comparison concerned the autoAb rates determined every 6 months over 2 years, then the titer variations between T0 and T3 were compared, and, finally, the induction of these autoAb in initially ANA-negative patients. The small number of SPA patients prescribed adalimumab precluded their analysis.
Evolution of ANA and Anti-dsDNA AutoAb Positivity under Anti-TNFα Therapy in RA Patients ANA-negative at T0
autoAb, n (%) Time
Infliximab (n = 48)
Etanercept (n = 30)
Adalimumab (n = 17)
Evolution of ANA and Anti-dsDNA AutoAb Positivity under Anti-TNFα Therapy in SPA Patients ANA-negative at T0
autoAb, n (%) Time
Etanercept (n = 29)
Infliximab (n = 44)
For the entire population, positivity of IgG anti-dsDNA autoAb was observed in eight patients for when this seroconversion was confirmed with the Farr’s test in six of eight cases. With this second method, which is usually more specific for systemic lupus erythematosus, levels of IgG anti-dsDNA were very low, ranging from 8 to 11 IU/ml, and remained stable over the follow-up patients.
Impact of RA or SPA on the Induction of ANA and Anti-dsDNA AutoAb for a Given Biologic
We analyzed the impact of the rheumatism on this aspect of autoimmunity to be sure that the underlying disease did not intervene, at least in part, in the emergence of these autoAb. For infliximab and etanercept, the appearance of autoAb, the variation of the titers, and the seroconversion rates were compared between the two diseases. Under etanercept, the rheumatism did not affect the variation of the titers or rates or ANA or anti-dsDNA autoAb induction over the 2 years of treatment. At T0, RA patients prescribed infliximab had significantly higher ANA and anti-dsDNA autoAb rates than SPA patients, but no significant difference was observed thereafter. ANA and anti-dsDNA autoAb titers were the same, regardless of the rheumatism considered, at all evaluation times. In addition, the T0–T3 variation of ANA titers was the same for both entities; in contrast, anti-dsDNA autoAb titers increased more in SPA patients (P < 0.02).
Influence of Concomitant Therapies on ANA and Anti-dsDNA AutoAb Induction
The influence of combined therapy with oral immunosuppressants and/or corticosteroids was also investigated. Finally, the impact of TNFα-blocker dose intensification on this induced autoimmunity was evaluated. The effect of MTX, leflunomide, and/or corticosteroids was analyzed for the entire population, then for the subgroup of RA and SPA patients ANA-negative before starting biotherapy with one of the three agents. No comparison could be made for patients treated with infliximab because almost all of them also took an immunosuppressant (68 with versus five without). Combining an immunosuppressant with etanercept or adalimumab had no impact on ANA and anti-dsDNA autoAb appearance or titer increase (P = 0.1–1). Corticosteroid intake at T0 did not influence ANA or anti-dsDNA autoAb titers from T1 to T3 regardless of the TNFα blocker considered (P = 0.1–1). Infliximab dose escalation had no impact on ANA and anti-dsDNA autoAb appearance or their titers and frequencies in RA and SPA patients over 18 months of follow-up (P = 0.1–0.9).
Evaluation of Possible Relationships Between ANA or Anti-dsDNA AutoAb Appearance and/or Titer Variations and Therapeutic Responses
Potential associations between the biotherapy and ANA and anti-dsDNA autoAb titer variations were also examined. These possible relationships were explored by rheumatism and TNFα blocker at all evaluation times over the 2-year follow-up period. Therapeutic responses were not associated with ANA and anti-dsDNA autoAb titers when infliximab or etanercept was considered for SPA patients (P = 0.9 and 0.15, respectively) or RA patients (P = 1 and 0.15, respectively). Therefore, the response to treatment is independent of ANA and anti-dsDNA autoAb titer variations regardless of the rheumatism and the TNFα biologic prescribed.
Evaluation of Possible Relationship Between Occurrence of Autoantibodies and Clinical Manifestations
Only one case of lupus cutaneous was observed among patients having IgG anti-dsDNA antibodies.
Evaluation of Possible Relationships Between RA-associated AutoAb (RF and Anti-CCP) and Therapeutic Responses
The evolution of RA-associated autoAb as a function of the response to biotherapy was examined for each TNFα blocker and for all RA patients treated with one of these agents.
Under infliximab, at T1 and T4, the patients with the lowest latex or Waaler–Rose test-detected RF titers responded significantly better, as did those with Waaler–Rose test-detected RF at T3. On the other hand, the anti-CCP titers did not fluctuate as a function of the therapeutic response.
Under etanercept, at T1, the patients with lower Waaler–Rose titers were significantly better responders. At T1 and T3, the patients with lower anti-CCP titers were also significantly better responders.
Under adalimumab, at T3 of follow-up, the patients with the lowest latex or Waaler–Rose test-detected RF compared to T0 values were significantly better responders. The anti-CCP autoAb titers did not fluctuate as of function of the response to treatment.
Relationships between the evolution of RF and anti-CCP autoAb titers and RA patient’s therapeutic responses to anti-TNFα therapy
Titer variation versus T0
Hence, the anti-CCP autoAb titers did not seem to be associated with the response to treatment despite significant associations found under etanercept at certain times during follow-up. Concerning RF measured by agglutination tests, their titers diminished in parallel with the response to treatment regardless of the TNFα blocker prescribed.
This study is the first to compare simultaneously the impact of three TNFα blockers on ANA in TNFα-blocker-naïve patients with uncontrolled RA or SPA (n = 251) followed in the same center. The median disease duration for both groups was 8 years, with 1–2 years of follow-up and biannual collection of clinical, biological, and therapeutic data. Our observations showed that ANA induction differed among the three agents and was most pronounced with infliximab compared to etanercept and, to a lesser degree, adalimumab. ANA and anti-dsDNA autoimmunity were not influenced by the underlying rheumatism or TNFα-blocker-combined therapies (immunosuppressants and/or corticosteroids). In addition, RF but not anti-CCP titers were associated with the RA therapeutic response.
First, we investigated ANA induced by the three biologics. Our results concurred with those obtained in the majority of the earlier studies that had examined only infliximab’s impact on the emergence of ANA [15, 19, 20, 25, 26, 28, 29, 34, 35] and the few studies that had assessed the effects of etanercept or adalimumab [23, 28, 29, 35]. Indeed, etanercept did not appear to induce ANA and anti-dsDNA autoimmunity, while, as reported by Atzeni et al , adalimumab did so in RA patients. To the best of our knowledge, no study has described ANA and anti-dsDNA autoimmunity induced by the latter biotherapy in SPA patients.
The originality of our study is the simultaneous evaluation of these three biologics, especially infliximab vs etanercept and the latter vs adalimumab in RA patients. Indeed, only two trials compared the effects of different TNFα blockers on ANA. In 2005, Eriksson et al.  conducted the first comparative study on RA patients, 53 treated with infliximab and six with etanercept for 1 year, and found ANA induction only under infliximab. Also, in 2005, De Rycke et al.  evaluated ANA induction in 34 SPA and 59 RA patients after 2 years of treatment with infliximab and in 20 SPA patients treated with etanercept for 1 year; ANA induction was found under infliximab in both diseases, but not etanercept.
In the present study, ANA induction was more important under infliximab than with the two other TNFα blockers, both in RA and SPA patients. Our results about the frequency of ANA positivity over a 2-year follow-up period in RA and SPA patients receiving infliximab are in accordance with those previously reported. Indeed, after 1 year under infliximab, the percentages of ANA positivity in those patients range from 65% to 89% using a threshold of positivity of 1:160 [25, 26, 28–30, 34, 35]. Nevertheless, in clinical practice, this ANA induction has no clinical implications. Our attention is focused on “more specific” autoAb such as anti-dsDNA. Although the data concerning the anti-dsDNA seroconversion are controversial in previous studies, the present work showed that induction of anti-dsDNA autoAb is very low (<5%) without differences among the three biologic agents. This low prevalence of anti-dsDNA autoAb of IgG isotype is not surprising, since autoantibodies that appeared under TNF-blocking agents are of IgM class. More importantly, for most patients, seroconversion of IgG anti-dsDNA is not associated with the appearance of lupus manifestations . If clinical signs appear, they are often limited to cutaneous rash (malar erythema) like in one patient of the present study.
ANA appearance under TNFα blockers is not surprising and is linked, in part, to the blockage of TNFα activity. Indeed, ANA synthesis depends on interferon-γ (IFNγ), a cytokine produced by plasmatoid dendritic cells. TNFα inhibition leads to dendritic cell proliferation, which results in the secretion of IFNγ, which, in turn, activates ANA-synthesizing plasmocytes.
The question remains, why is this autoAb induction greater under infliximab? Infliximab and adalimumab monoclonal Ab (mAb) might generate different responses, or the different mAb types, one chimeric and the other human, might be responsible for the degree of ANA induction. Moreover, the difference between the structures and mechanisms of action of etanercept, a fusion protein constituted of an Fc fragment of human IgG and two identical extracellular chains of the p75 TNFα receptor, and those mAb might be easier to understand. The mAb act primarily by blocking circulating free TNFα and have stronger cytotoxic effects on activated cells because they bind to membrane-expressed TNFα and could thus lead to their lysis via complement-mediated cytotoxicity. Anti-TNFα mAb also have a role in the non-specific activation of B lymphocytes. Soluble TNFα receptors intervene by competitive inhibition via their binding to TNFα and preventing it from binding to its cell surface receptor. Thus, they reproduce a physiological mechanism of TNFα regulation.
Etanercept seems not to induce apoptosis, but this notion remains controversial . It also inhibits lymphotoxin-β. Finally, according to one study, etanercept and infliximab differently affected T cell functions . Etanercept enhanced IFNγ production but no modification of interleukins (IL)-4 and 10 levels, while infliximab diminished production of Th1 cytokines, IL-2 and IFNγ, which in turn would favor increased Th2 cytokines IL-4 and -10, implicated in lupus and anti-dsDNA-autoAb secretion .
Notably, the increased ANA and anti-dsDNA-autoAb titers during TNFα blocker administration do not seem to be associated with the appearance of anti-infliximab Ab whose presence is associated with the progressive diminution of therapeutic efficacy and/or the appearance of allergic reactions to its perfusion [38, 39]. However, ANA appearance was not associated with therapeutic response in our study, which would seem to suggest that therapeutic escape is not linked to ANA and anti-dsDNA autoimmunity. Nevertheless, the production of human anti-chimeric antibodies (HACA) seems to be higher under infliximab than adalimumab . Until now, no study has demonstrated a correlation between anti-infliximab Ab production (HACA) and that of ANA. Unfortunately, a possible relationship between HACA and these autoAb populations could not be evaluated herein.
Because SPA is an inflammatory disease, while RA combines inflammatory and autoimmune components, our demonstration that the rheumatism did not intervene in the appearance of these autoAb is an intriguing notion. This finding confirms the preponderant role of TNFα blockers in this induced autoimmunity. Nevertheless, De Rycke et al.  had reported a difference between the two entities. Indeed, after 1 year of follow-up, the induction of anti-dsDNA autoAb was significantly higher in SPA than RA patients, which those authors attributed to the combination of MTX and infliximab for RA patients and a higher infliximab dose for SPA patients. Those two findings were not corroborated in our study, but it must be kept in mind that the majority of SPA patients received the same infliximab dose (3 mg/kg) as RA patients.
Ferraro-Peyret et al.  described ANA induction under infliximab in both pathologies, but they did not compare the two. In addition, whether conventional DMARD or corticosteroids, combined treatments were reported to have no effects on ANA and anti-dsDNA-autoAb positivity . Notably, our data also confirmed that adjunction of an immunosuppressant (leflunomide or MTX) had no impact on induced autoimmunity. Finally, we observed no influence of infliximab dose intensification on the appearance or variation of ANA or anti-dsDNA-autoAb titers over 18 months of follow-up.
The evolution of RA-associated autoAb under any of the three TNFα blockers agreed well with some previously reported findings [15, 18, 20]. Indeed, herein, the evolution of RF titers seemed to be associated with the therapeutic response, unlike anti-CCP. Generally speaking, RF titers decline under treatment with an immunomodulator and are usually linked to disease activity and outcome; disease control results in diminished RF production, as recently hypothesized . In contrast, anti-CCP-autoAb synthesis did not seem to be attenuated by the TNFα blockers, as previously observed with other molecules, like MTX . This inefficacy probably reflects that anti-CCP autoAb are the signature of the pathogenic mechanisms at work in RA. Indeed, anti-CCP-autoAb appearance results from interactions between environmental factor(s) (infectious agent, tobacco…) that trigger the inflammatory state, responsible for the citrullination process, and genetic factors (shared epitopes, polymorphisms of certain genes) that favor the emergence of autoimmunity to citrullinated proteins . Because anti-TNFα therapies are not curative, these disease markers are not modified by them.
In conclusion, this study is the first to evaluate the impact of three TNFα-blockers on ANA and anti-dsDNA autoAb in patients with active RA or SPA followed in a single center. This induced autoimmunity was significantly more pronounced under infliximab than etanercept or, to a lesser extent, adalimumab. The differences observed among the three biotherapies seem to reflect their different molecular natures and/or mechanisms of action. However, the emergence of ANA and anti-dsDNA autoimmunity was independent of the therapeutic response, like that existing between HACA and therapeutic escape. ANA and anti-dsDNA autoAb were not influenced by the underlying pathology or the combined therapeutic agents, be they immunosuppressants (MTX, leflunomide) or corticosteroids. Interestingly, despite some differences in the seroconversion of IgG anti-dsDNA or ANA between TNF-blocking agents, those biologic abnormalities are not generally associated with the occurrence of autoimmune diseases such as systemic lupus erythematosus. Thus, in clinical practice, even though there are differences in the induction of autoantibodies with the three anti-TNFα therapies, there is no interest to look for those autoantibody populations because of the lack of association with autoimmune diseases. Finally, these biologics do not have the same impact on the two principal RA-associated autoAb (RF and anti-CCP).
The authors thank Janet Jacobson for editorial assistance.