Quantifying anti-cyclic citrullinated peptide titres: clinical utility and association with tobacco exposure in patients with rheumatoid arthritis

Anti-Citrullinated Protein Antibody Titers Are Independently Modulated by Both Disease Activity and Conventional or Biologic Anti-Rheumatic Drugs

This study aimed to analyze the factors that influence anti-citrullinated protein antibody (ACPA) titers in a seropositive early arthritis (EA) population under non-protocolized treatment with disease-modifying anti-rheumatic drugs (DMARDs). A total of 130 ACPA-positive patients from the PEARL (Princesa Early Arthritis Longitudinal) study were studied along a 5-year follow-up. Sociodemographic, clinical, and therapeutic variables, along with serum samples, were collected at five visits by protocol. Anti-cyclic citrullinated peptide 2 (CCP2) ACPA titers were measured by ELISA. The effect of different variables on anti-CCP2 titers was estimated using longitudinal multivariate analysis models, nested by visit and patient. Data from 471 visits in 130 patients were analyzed. A significant decrease in anti-CCP2 titers was observed at all time-points, compared to baseline, following the decline of disease activity. In the multivariate analysis, active or ever smoking was significantly associated with the highest anti-CCP2 titers while reduction in disease activity was associated with titer decline. After adjusting for these variables, both conventional synthetic (cs) and biologic (b) DMARDs accounted for the decline in anti-CCP2 titers as independent factors. Conclusion: In patients with EA, an early and sustained reduction in ACPA titers can be detected associated with the decline in disease activity, irrespective of the treatment used.

Does smoking affect level of seropositivity in RA? A post-HOC global and inter-country analysis of COMORA cohort

To study the association of smoking status and the level of seropositivity in RA patients from COMORA Cohort. A post hoc analysis of COMORA database included 3439 RA patients was performed. Current smokers or recently quitted (< 3 years) were initially compared to those who never smoked or stopped > 3 years (Group I vs. II) regarding their seropositivity status (high positive, low positive and negative) for Rheumatoid Factor (RF) or Anti-citrullinated antibodies (ACPA). A further comparison was made between current smokers (Group III) and never smoked patients (Group IV). Analysis was also done on the individual country level for the 17 countries included in the COMORA study. Out of 3439 RA patients, 705 (20.5%) were smokers (group I), and 2734 (79.5%) were non-smokers (group II). Significantly more patients in group I, 442 (62.7%), had high levels of seropositivity than those in group II, 1556 (56.9%), [P = 0.006, OR 1.27 (95% CI, 1.07-1.5)]. More current smoker patients (group III-286 out of 456 "62.7%") had high levels of seropositivity than never smoked patients (group IV-1236 out of 2191 "56.4%"), with significant difference [P = 0.013, OR 1.3 (95% CI, 1.06-1.6)]. In 11 countries, higher proportions of patients with high level of seropositivity in group I was found, with statistical significance in four countries. Smoking was associated with higher level of seropositivity in patients with RA in this post hoc analysis, both on a global level and in certain individual countries. As smoking is a modifiable risk factor, studying the effects of quitting smoking on level of seropositivity and other disease parameters is warranted.

Association between periodontitis and anti-citrullinated protein antibodies in rheumatoid arthritis patients: a cross-sectional study

AIM

The aim of this study was to evaluate the association between periodontal parameters related with the periodontal disease severity and the presence and levels of anti-citrullinated protein antibodies (ACPAs) in rheumatoid arthritis (RA) patients.

MATERIALS AND METHODS

This cross-sectional study included 164 RA patients. Socio-demographics and RA disease characteristics, including ELISA-detected ACPA (anti-CCP-2), were recorded. Exposure was assessed by periodontal parameters: plaque index (PI), bleeding on probing (BoP), probing pocket depth, and clinical attachment levels (CAL). Presence and levels of ACPAs (outcome) and exposure variables were compared by both parametric and non-parametric tests and associations were evaluated by adjusted odds ratio (OR).

RESULTS

A significant association was observed between the presence of anti-CCP antibodies and severity of periodontal outcomes such as the mean CAL (OR 1.483, p = 0.036), mean PI (OR 1.029, p = 0.012), and the number of pockets ≥ 5 mm (OR 1.021, p = 0.08). High anti-CCP antibodies levels were associated with mean CAL, mean PI, and number of pockets ≥ 5 mm with an OR of 1.593 (p = 0.043), 1.060 (p <  0.001), and 1.031 (p = 0.031), respectively. Furthermore, a significant increase of 4.45 U/mL in anti-CCP antibodies levels (p = 0.002) in RA patients was found for each pocket ≥ 5 mm after adjusting for age, gender, smoking, time of disease evolution, and RA activity.

CONCLUSIONS

In RA patients, the severity of periodontal conditions such as mean CAL, mean PI, and the number of pockets ≥ 5 mm were linearly associated with both the presence and levels of anti-CCP antibodies.

Abatacept reduces disease activity of rheumatoid arthritis independently of modulating anti-citrullinated peptide antibody production

Abatacept may exert its clinical effect on rheumatoid arthritis (RA) by suppressing anti-cyclic citrullinated peptide (CCP) antibody production. This study was undertaken to test this hypothesis by examining the changes of disease activity of RA and anti-CCP antibody levels over time after starting abatacept. Sixty Japanese RA patients who started abatacept were included in this multicenter, prospective observational study. Simple Disease Activity Index (SDAI) and anti-CCP antibody levels were evaluated at 12, 24, and 52 weeks. The mean SDAI score significantly decreased within 12 weeks after starting abatacept and was maintained thereafter. On the contrary, the mean anti-CCP antibody levels did not change until 52 weeks. At the individual level, there were substantial changes of anti-CCP antibody levels, but these were not correlated with the changes of disease activity at any time points. Thus, abatacept reduces the disease activity of RA independently of modulating anti-CCP antibody production.

"NETtling" the host: Breaking of tolerance in chronic inflammation and chronic infection

How and why we break tolerance to self-proteins still remains a largely unanswered question. Neutrophils have been identified as a rich source of autoantigens in a wide array of autoimmune diseases that arise as a consequence of different environmental and genetic factors, e.g. rheumatoid arthritis (RA), lupus, vasculitis, cystic fibrosis (CF) etc. Specifically, neutrophil extracellular trap (NET) formation has been identified as a link between innate and adaptive immune responses in autoimmunity. Autoantigens including neutrophil granular proteins (targeted by anti-neutrophil cytoplasmic antibodies, ANCA) as well as post-translationally modified proteins, i.e. citrullinated and carbamylated proteins targeted by anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein antibodies (ACarPA), respectively, localize to the NETs. Moreover, NETs provide stimuli to dendritic cells that potentiate adaptive autoimmune responses. However, while NETs promote inflammation and appear to induce humoral autoreactivity across autoimmune diseases, the antigen specificity of autoantibodies found in these disorders is striking. These unique autoantigen signatures suggest that not all NETs are created equal and that the environment in which NETs arise shapes their disease-specific character. In this review article, we discuss the effects of different stimuli on the mechanism of NET formation as well as how they contribute to antigen specificity in the breaking of immune tolerance. Specifically, we compare and contrast the autoreactive nature of NETs in two settings of chronic airway inflammation: one triggered by smoking, a recognized environmental NET stimulus in RA patients, and one mediated by Pseudomonas aeruginosa, the most prevalent lung pathogen in CF patients. Finally, we draw attention to novel findings that, together with the specific environmental/chemical stimuli, should be taken into account when investigating how and why antigen specificity arises in the context of NET formation.

An observation on the severity of periodontal disease in past cigarette smokers suffering from rheumatoid arthritis- evidence for a long-term effect of cigarette smoke exposure?

Background

Rheumatoid arthritis (RA) and cigarette smoking are both risk factors for periodontal disease (PD). Previous research suggests that systemic inflammatory conditions and cigarette smoking may act in synergy, and their co-occurrence leads to a much higher risk of developing severe stage PD than what the combination of their individual risks would suggest. We originally sought to test this in the case of RA, but it turned out that the majority of our patients were former smokers, who smoked for prolonged periods in the past. For that reason, we decided to shift our focus toward the possible effects of past chronic cigarette smoke exposure.

Methods

The data of 73 RA patients and 77 healthy controls were analyzed. The participants received a full-mouth periodontal examination to determine their periodontal status. Rheumatological indices and data on past tobacco use were also recorded. Both the patient and the control groups were divided into former smoker and non-smoker subgroups for the analyses. Non-smoker controls were used as the reference group.

Results

In the control group, smoking in history increased the odds of developing both the moderate and the severe stages of PD, but the change was not statistically significant. RA significantly, increased the odds of developing both stages in itself, but the highest odds were seen in the former smoker RA group.

Conclusion

Based on this surprising observation of ours, we hypothesize that chronic cigarette smoke might bring about permanent changes in the periodontal tissues, leading to their hypersensitivity to inflammatory challenges.

Nicotine drives neutrophil extracellular traps formation and accelerates collagen-induced arthritis

Objectives

The aim was to investigate the effects of nicotine on neutrophil extracellular traps (NETs) formation in current and non-smokers and on a murine model of RA.

Methods

We compared spontaneous and phorbol 12-myristate 13-acetate-induced NETosis between current and non-smokers by DNA release binding. Nicotine-induced NETosis from non-smokers was assessed by DNA release binding, NET-specific (myeloperoxidase (MPO)-DNA complex) ELISA and real-time fluorescence microscopy. We also used immunofluorescent staining to detect nicotinic acetylcholine receptors (nAChRs) on neutrophils and performed a functional analysis to assess the role of nAChRs in nicotine-induced NETosis. Finally, we investigated the effects of systemic nicotine exposure on arthritis severity and NETosis in the CIA mouse model.

Results

Neutrophils derived from current smokers displayed elevated levels of spontaneous and phorbol 12-myristate 13-acetate-induced NETosis. Nicotine induced dose-dependent NETosis in ex vivo neutrophils from healthy non-smokers, and co-incubation with ACPA-immune complexes or TNF-α facilitated a synergistic effect on NETosis. Real-time fluorescence microscopy revealed robust formation of NET-like structures in nicotine-exposed neutrophils. Immunofluorescent staining demonstrated the presence of the α7 subunit of the nAChR on neutrophils. Stimulation of neutrophils with an α7-specific nAChR agonist induced NETosis, whereas pretreatment with an nAChR antagonist attenuated nicotine-induced NETosis. Nicotine administration to mice with CIA exacerbated inflammatory arthritis, with higher plasma levels of NET-associated MPO-DNA complex.

Conclusion

We demonstrate that nicotine is a potent inducer of NETosis, which may play an important role in accelerating arthritis in the CIA model. This study generates awareness of and the mechanisms by which nicotine-containing products, including e-cigarettes, may have deleterious effects on patients with RA.

Arthritis models: usefulness and interpretation

Animal models of arthritis are used to better understand pathophysiology of a disease or to seek potential therapeutic targets or strategies. Focusing on models currently used for studying rheumatoid arthritis, we show here in which extent models were invaluable to enlighten different mechanisms such as the role of innate immunity, T and B cells, vessels, or microbiota. Moreover, models were the starting point of in vivo application of cytokine-blocking strategies such as anti-TNF or anti-IL-6 treatments. The most popular models are the different types of collagen-induced arthritis and arthritis in KBN mice. As spontaneous arthritides, human TNF-α transgenic mice are a reliable model. It is mandatory to use animal models in the respect of ethical procedure, particularly regarding the number of animals and the control of pain. Moreover, design of experiments should be of the highest level, animal models of arthritis being dedicated to exploration of well-based novelties, and never used for confirmation or replication of already proven concepts. The best interpretations of data in animal models of arthritis suppose integrated research, including translational studies from animals to humans.

Environmental Basis of Autoimmunity

The three common themes that underlie the induction and perpetuation of autoimmunity are genetic predisposition, environmental factors, and immune regulation. Environmental factors have gained much attention for their role in triggering autoimmunity, with increasing evidence of their influence as demonstrated by epidemiological studies, laboratory research, and animal studies. Environmental factors known to trigger and perpetuate autoimmunity include infections, gut microbiota, as well as physical and environmental agents. To address these issues, we will review major potential mechanisms that underlie autoimmunity including molecular mimicry, epitope spreading, bystander activation, polyclonal activation of B and T cells, infections, and autoinflammatory activation of innate immunity. The association of the gut microbiota on autoimmunity will be particularly highlighted by their interaction with pharmaceutical agents that may lead to organ-specific autoimmunity. Nonetheless, and we will emphasize this point, the precise mechanism of environmental influence on disease pathogenesis remains elusive.

Clinical and laboratory factors associated with interstitial lung disease in rheumatoid arthritis

OBJECTIVE

The objective of this study is to examine the clinical, genetic, and environmental factors associated with interstitial lung disease (ILD) in rheumatoid arthritis (RA).

METHOD

We recruited patients with RA from rheumatology practices at the time of a scheduled visit. Each patient participated in a comprehensive assessment that included ascertainment of age, sex, joint tenderness and swelling, subcutaneous nodules, disease severity, use of methotrexate and prednisone, smoking status, rheumatoid factor (RF), antibodies against cyclic citrullinated peptide (anti-CCP),erythrocyte sedimentation rate (ESR), the 28-joint Disease Activity Score (DAS28), and the presence of the HLA-DRB1 shared epitope (SE). As part of a thorough quantification of comorbidity, we identify all comorbid conditions, including ILD. We examined variables associated with ILD using logistic regression. We tested interaction terms between SE and other covariates.

RESULTS

We studied 779 RA patients, among whom, ILD was recognized clinically in 69 (8.8 %). Variables significantly associated with ILD in a multivariable analysis included male sex, RA duration, the ESR, the DAS28, anti-CCP, and RF. There was a significant interaction between the HLA-DRB1 SE and smoking, ILD being associated with smoking only in the presence of SE. The association between ILD and anti-CCP, RF, and the ESR displayed a biological gradient, higher titers being more strongly associated with ILD.

CONCLUSION

Anti-CCP antibodies and the RF may be pathogenically related to ILD. The association between ILD and smoking is dependent on the HLA-DRB1 SE, which may reflect gene-environment interaction.

Circulating anti-citrullinated peptide antibodies, cytokines and genotype as biomarkers of response to disease-modifying antirheumatic drug therapy in early rheumatoid arthritis

Background

To measure circulating anti-citrullinated peptide antibodies (ACPA) and cytokines pre- and 6 months post-therapy as a strategy to predict and optimize responses to traditional disease-modifying antirheumatic drugs (DMARDs) in early RA, which is an unmet need in developing countries.

Patients and methods

A cohort of 140 predominantly (88.5 %) black female South African patients with early RA was treated with synthetic DMARDs, mostly methotrexate (MTX) alone, or in combination with low-dose oral corticosteroids (CS). Circulating ACPA and a panel of circulating cytokines/chemokines/growth factors were measured at baseline and after 6 months of therapy in relation to disease activity and Shared Epitope (SE).

Results

Following 6 months of therapy, the median simplified disease activity index (SDAI) declined from a baseline of 41.4 to 16.0 (p = 0.0001) for the entire cohort, which was paralleled by significant falls in median serum ACPA levels (516.6 vs. 255.7 units/ml, p = <0.0001) and several of the circulating cytokines (IL-4, IL-7, IL-8, G-CSF, VEGF; p < 0.0010 – p < 0.0001) which were most evident in the subgroup of patients treated with a combination of MTX and CS. Although biomarker concentrations decreased most notably in the low-disease activity group post-therapy, no significant correlations between these biomarkers and disease activity were observed, Baseline ACPA levels, but not SDAI or cytokines, were significantly higher in the subgroup of risk allele-positive patients (561.1 vs. 331.9 units/ml, p < 0.05), while no associations with ACPA and a smoking history were evident.

Conclusions

The use of DMARDs in RA is associated with significant decreases in ACPA and cytokines which did not correlate with changes in SDAI, precluding the utility of serial measurement of these biomarkers to monitor early responses to therapy, but may have prognostic value.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0587-1) contains supplementary material, which is available to authorized users.

Smoking and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease caused by both genetic and environmental factors. Smoking has been implicated as one of the most important extrinsic risk factors for its development and severity. Recent developments have shed light on the pathophysiology of RA in smokers, including oxidative stress, inflammation, autoantibody formation and epigenetic changes. The association of smoking and the development of RA have been demonstrated through epidemiologic studies, as well as through in vivo and animal models of RA. With increased use of biological agents in addition to standard disease-modifying antirheumatic drugs (DMARDs), there has been interest in how smoking affects drug response in RA treatment. Recent evidence suggests the response and drug survival in people treated with anti-tumour necrosis factor (anti-TNF) therapy is poorer in heavy smokers, and possible immunological mechanisms for this effect are presented in the current paper.

Anti-CCP in systemic lupus erythematosus patients: a cross sectional study in Brazilian patients

Recently, it has been found that some lupus patients may have anti-cyclic citrullinated peptide antibodies (anti-CCP), although the clinical significance of such finding is not well established. Systemic lupus erythematosus (SLE) patients may have joint complaints that are very similar to those observed in rheumatoid arthritis (RA). In early stages of disease, this form of arthritis can be difficult to differentiate from RA, so it is not rare that some SLE patients are initially misdiagnosed to have this disease. This study aims to investigate the prevalence of anti-CCP in SLE patients from Southern Brazil and its association with clinical and serological profiles. One hundred nine SLE patients were studied for anti-CCP and compared with data of 156 RA patients and 100 healthy volunteers. Comparison of clinical and autoantibody profile of anti-CCP-positive and anti-CCP-negative SLE patients was done. All SLE patients positive of anti-CCP were submitted to hand and feet X-rays. Anti-CCP was positive in 15 of 109 SLE patients, and one of them had confirmed the diagnosis of rhupus. This prevalence was significantly higher than in healthy controls (p = 0.0004) and lower than in RA patients (p < 0.0001). No relationship could be found with clinical profile, including joint complaints. SLE patients with anti-CCP had higher prevalence of anti-Ro (p = 0.02) and anti-La (p = 0.004) autoantibodies, in comparison with those negative to anti-CCP. We found that 13.7% of Brazilian patients with SLE have positive anti-CCP. Patients with anti-CCP showed higher prevalence of anti-Ro and anti-La autoantibodies than those negative for anti-CCP. Only a careful and prolonged follow-up will reveal the real clinical value of these markers in each patient individually.

Metaanalysis of the association of smoking and PTPN22 R620W genotype on autoantibody status and radiological erosions in rheumatoid arthritis

OBJECTIVE

To investigate the interrelationships among smoking, protein tyrosine phosphatase non-receptor 22 (PTPN22) R620W (rs2476601) genotype, and anticitrullinated peptide antibody (ACPA) status; and among smoking, PTPN22 R620W genotype, and presence of bone erosions overall and separately by ACPA status in patients with rheumatoid arthritis (RA).

METHODS

Six studies totaling 2680 patients with RA were included in a Mantel-Haenszel fixed-effects metaanalysis investigating ACPA status and up to 8 studies totaling 3172 patients with RA were included in a Mantel-Haenszel fixed-effects metaanalysis investigating presence of erosive damage.

RESULTS

Evidence was found for an increase in the odds of ACPA positivity for ever smoking (OR 1.56, 95% CI 1.28-1.90, p = 8.5 × 10(-6)), carriage of at least 1 of the PTPN22 risk alleles (OR 1.50, 95% CI 1.13-2.00, p = 5.5 × 10(-3)) and both ever smoking and carriage of at least 1 of the PTPN22 risk alleles (OR 2.22, 95% CI 1.69-2.91, p = 8.3 × 10(-9)). There was no evidence of an association between presence of erosive damage and smoking status or carriage of PTPN22 risk alleles when analyzed overall or separately by ACPA status.

CONCLUSION

This metaanalysis indicates that both smoking and the PTPN22 risk allele are associated with the risk of ACPA positivity. There was insufficient evidence to establish a relationship in either direction between PTPN22 and smoking with erosive damage, despite evidence that ACPA positivity is associated with erosive damage.

Anti-citrullinated protein antibodies: role in pathogenesis of RA and potential as a diagnostic tool

Rheumatoid arthritis is an autoimmune disorder which involves inflammation of the synovial tissue, leading to synovial proliferation, bone erosion and ultimately joint disability. It is a complex disorder, and the proper etiology is still unknown. Both environmental and genetic factors are responsible for the development of rheumatoid arthritis. Clinically, the disease is generally diagnosed by the presence of auto-antibodies like rheumatoid factor. But these are not specifically associated with rheumatoid arthritis. These are also present in patients with other autoimmune disorders and also in healthy persons. Citrullinated epitopes are shown to be more specific for rheumatoid arthritis. Citrullination normally occurs in cells undergoing apoptosis, and hence, citrullinated proteins are cleared from body and not encountered by immune system. However, in rheumatoid arthritis patients, these are not cleared. Anti-citrullinated protein antibodies are detectable in patients at risk of rheumatoid arthritis long before the onset of the disease. The concentration of which normally increases as the disease progress. Hence, these are important for diagnosis of rheumatoid arthritis. This review is focused on the importance of anti-citrullinated protein antibodies in disease pathogenesis and its importance in the diagnosis of rheumatoid arthritis.

Chronic smoke exposure induces rheumatoid factor and anti-heat shock protein 70 autoantibodies in susceptible mice and humans with lung disease

The impact of cigarette smoke (CS), a risk factor for rheumatoid arthritis (RA), on sauto-antibody production was studied in humans and mice with and without chronic lung disease (LD). Rheumatoid factor (RF), anti-cyclic citrullinated peptides (CCPs), and anti-HSP70 autoantibodies were measured in several mouse strains and in cohorts of smokers and nonsmokers with and without autoimmune disease. Chronic smoking-induced RFs in AKR/J mice, which are most susceptible to LD. RFs were identified in human smokers, preferentially in those with LD. Anti-HSP70 auto-antibodies were identified in CS-exposed AKR/J mice but not in ambient air exposed AKR/J controls. Whereas inflammation could induce anti-HSP70 IgM, smoke exposure promoted the switch to anti-HSP70 IgG autoantibodies. Elevated anti-CCP autoantibodies were not detected in CS-exposed mice or smokers. AKR/J splenocytes stimulated in vitro by immune complexes (ICs) of HSP70/anti-HSP70 antibodies produced RFs. The CD91 scavenger pathway was required as anti-CD91 blocked the HSP70-IC-induced RF response. Blocking Toll-like receptors did not influence the HSP70-IC-induced RFs. These studies identify both anti-HSP70 and RFs as serological markers of smoke-related LD in humans and mice. Identification of these autoantibodies could suggest a common environmental insult, namely CS, in a number of different disease settings.

Tobacco and other environmental risk factors in rheumatoid arthritis

Many environmental factors have been associated with an increased risk of developing Rheumatoid Arthritis (RA), but so far smoking is the only environmental risk factor that has been extensively studied and widely accepted. Smoking is associated with an increased risk of developing seropositive RA (RF and/or ACPA). Recent studies show that tobacco smoking can influence disease phenotype, with the development of more aggressive disease and greater joint damage; but other studies show contradictory results. Recent data suggests that response to antirheumatic therapy in RA is worse in smokers. In this article we review different environmental factors that have been associated with an increased risk of developing RA, with a special interest in tobacco smoking.

Citrullination under physiological and pathological conditions

Citrullination, one of the enzymatic posttranslational modifications has become a hot topic of recent research as it is involved in various physiological and pathological processes. Antibodies against citrullinated proteins called anti-citrullinated protein antibodies, are the hallmark (diagnostic and prognostic factors) of rheumatoid arthritis, and are specific for the disease. Citrullination has an important role in the normal function of the immune system, skin keratinization, the insulation of neurons and the plasticity of the central nervous system including its essential role in gene regulation. Abnormal citrullination has been proposed to play a role in multiple sclerosis and Alzheimer's disease, and recent research has drawn attention to its implication in tumorigenesis. Still, it is unclear whether citrullination is the cause or the consequence of these pathological alterations. Here, we discuss crucial aspects of citrullination during both physiological and pathological conditions.

Antibodies to citrullinated protein antigens (ACPAs): clinical and pathophysiologic significance

Antibodies to citrullinated protein antigens (ACPAs) are highly specific for rheumatoid arthritis (RA) and are useful in the diagnosis of RA as well as the prediction of the course and outcomes of disease. Multiple methodologies exist for measuring ACPAs, including the widely available tests for anticyclic citrullinated peptide antibodies and for antibodies to mutated/modified citrullinated vimentin. These methodologies overall have similar diagnostic accuracies for RA, although there is some variability. The discovery of ACPAs and the biology of citrullination have also led to important advances in the understanding of the pathophysiology and development of RA, especially regarding the relationship between potential genetic and environmental risk factors for RA. Going forward, research into autoimmunity to citrullinated proteins may help identify the specific etiology of RA and provide approaches for the prediction of future risk of disease, and ultimately prevention of RA.

Air pollution in autoimmune rheumatic diseases: a review

Air pollution consists of a heterogeneous mixture of gasses and particles that include carbon monoxide, nitrates, sulfur dioxide, ozone, lead, toxic by-product of tobacco smoke and particulate matter. Oxidative stress and inflammation induced by inhaled pollutants may result in acute and chronic disorders in the respiratory system, as well as contribute to a state of systemic inflammation and autoimmunity. This paper reviews the mechanisms of air contaminants influencing the immune response and autoimmunity, and it focuses on studies of inhaled pollutants triggering and/or exacerbating rheumatic diseases in cities around the world. Remarkably, environmental factors contribute to the onset of autoimmune diseases, especially smoking and occupational exposure to silica in rheumatoid arthritis and systemic lupus erythematosus. Other diseases such as scleroderma may be triggered by the inhalation of chemical solvents, herbicides and silica. Likewise, primary vasculitis associated with anti-neutrophil cytoplasmic antibody (ANCA) may be triggered by silica exposure. Only few studies showed that air pollutants could trigger or exacerbate juvenile idiopathic arthritis and systemic lupus erythematosus. In contrast, no studies of tropospheric pollution triggering inflammatory myopathies and spondyloarthropathies were carried out. In conclusion, air pollution is one of the environmental factors involved in systemic inflammation and autoimmunity. Further studies are needed in order to evaluate air pollutants and their potentially serious effects on autoimmune rheumatic diseases and the mechanisms involved in the onset and the exacerbation of these diseases.

Specific expression of PAD4 and citrullinated proteins in lung cancer is not associated with anti-CCP antibody production

Anti-citrullinated protein antibodies (ACPAs), produced against citrullinated proteins, are diagnostic and prognostic markers of rheumatoid arthritis (RA). The underlying mechanism that explains the connection of smoking, citrullination [catalyzed by peptidyl arginine deiminases (PADs)] and ACPAs is still unclarified in RA. Thus, we searched for a non-arthritic model in which an increased cell death allows the formation of autoantibodies. Data supporting that lung cancer might be a good candidate are as follows: (i) smoking plays a role in its pathogenesis, (ii) the disease is frequently accompanied by paraneoplastic syndrome, (iii) smoking increases citrullination in the lung, (iv) various types of malignancies are associated with increased citrullination and (v) lung cancer tissue shows similarities with RA synovium. Serum PAD4, rheumatoid factor (RF) and ACPA levels were measured in 42 lung cancer patients; expression of cytokeratin 7 (CK7), PAD4 and citrullinated proteins was visualized in 113 lung cancer tissues. All parameters were analyzed in correlation with smoking history. None of the patients had polyarthritis or autoimmune disease. Significantly increased RF levels were associated with higher PAD4 levels in smoker lung cancer patients compared with non-smokers. Both PAD4 and citrullination immunostaining strongly correlated with that of CK7 in lung cancer, however, did not differ according to smoking history. Two of 30 smoker lung cancer patients had high anti-cyclic citrullinated peptide levels. In conclusion, PAD4 and citrullination may be helpful in distinguishing lung cancer from healthy tissue. Smoking, abnormal serum PAD4 and RF levels may not be sufficient for the production of ACPAs and development of autoimmunity.

Cigarette smoking in primary Sjögren's syndrome: positive association only with ANA positivity

Smoking is well known to contribute to the pathogenesis and severity of some systemic autoimmune rheumatic diseases and especially to the production of certain autoantibodies. Primary Sjögren's syndrome (pSS) is an autoimmune disease, affecting primarily the exocrine glands. It may also cause extraglandular involvement in some cases. In this study, we aimed to determine the frequency of smoking habits in our cohort of pSS patients and to investigate whether the frequencies of autoantibody positivity and extraglandular involvement were significantly different between patients with and without smoking. In this cross-sectional study, 207 patients with pSS (F/M 203/4), fulfilling the United States-European Consensus Criteria, and 602 healthy controls (F/M 534/68) were included. Patients and controls were classified into five groups: never smokers, current smokers, former smokers; ever smokers, and passive smokers. The χ(2) and Kruskal-Wallis tests were used for statistical analysis; a p value of less than 0.05 was accepted as statistically significant. While the frequency of current smokers was significantly lower in the pSS group compared with the healthy controls (11.6 vs 22.3%), the frequencies of former smokers (30.4 vs 11.8%), ever smokers (42.0 vs 34.1%), and passive smokers (47.3 vs 37.5%) were significantly higher in the pSS group compared with the healthy controls. In pSS patients, only antinuclear antibody (ANA) positivity was significantly associated with smoking habits, while there was no significant association with other autoantibodies or with the presence of extraglandular involvement. We found that in pSS patients smoking was significantly associated only with ANA positivity. Unlike the deleterious effects of smoking upon disease severity and anti-cyclic citrullinated protein (CCP) antibody production in rheumatoid arthritis, we could not find any association of smoking with extraglandular involvement and/or anti-Ro/anti-La antibody positivity in pSS. These results are indeed in line with the limited number of previous studies reported in the literature. Further studies with higher numbers of pSS patients are required to confirm the seemingly negative association of smoking with pSS.

Anti-cyclic citrullinated peptide antibodies and rheumatoid factor in rheumatoid arthritis patients and relatives from Brazil

OBJECTIVES

To evaluate the prevalence of anti-cyclic citrullinated peptide (anti-CCP) antibodies and RF in RA patients and their relatives from Southern Brazil.

METHODS

Anti-CCP2 and IgM-RF were evaluated in 156 RA patients and 200 relatives. Sera from 100 healthy unrelated individuals were used as control. The anti-CCP2 was detected by ELISA and the IgM-RF using the latex agglutination test.

RESULTS

We identified 117 anti-CCP2 (75%)-positive and 106 RF (67.9%)-positive patients. Anti-CCP2 was increased in relatives (5.5%; 11/200) when compared with unrelated individuals (1%; P = 0.050). Titre of anti-CCP2 in RA patients did not differ from relatives [140.4 (75.7) vs 115.6 (84.2) U, respectively; P = 0.30]. Positive relatives were younger than patients for anti-CCP2 (P = 0.0081), RF (P < 0.001) and both concomitantly (P = 0.012), and although there was no difference for anti-CCP2 positivity according to gender, increased RF positivity and concomitant anti-CCP2/RF were observed in the female relatives (P = 0.067 and 0.082, respectively). No difference regarding the relative degree of tobacco use in relatives was detected. Among the 11 anti-CCP2-positive relatives, 2 females had RA diagnosis established and 6 individuals presented with joint symptoms suggestive of RA.

CONCLUSION

The results demonstrate a significant positivity of anti-CCP2 in relatives of RA patients from Brazil and reinforce the importance of serological tools to identify undiagnosed RA.

Anti-TNF-alpha agents are less effective for the treatment of rheumatoid arthritis in current smokers

OBJECTIVES

To assess if smoking status at the time of commencing an anti-TNF-alpha agent for rheumatoid arthritis (RA) reduces the likelihood of achieving at least a moderate response on the European League Against Rheumatism (EULAR) response criteria at 3-month assessment.

METHODS

All patients with RA treated with their first anti-TNF-alpha agent at the Department of Rheumatology, Derby Hospital NHS Trust between April 2001 and October 2008 were included in this retrospective case control study. Information about age, gender, disease duration, body mass index, smoking status (current smoker, ex-smoker, and nonsmoker), comorbidities, oral prednisolone use, and 28 joint 4 variables disease activity score (DAS28) at the time of commencing an anti-TNF-alpha agent was recorded. Details of rheumatoid factor (RF) and past and present disease modifying antirheumatic drugs were recorded. A case control study was carried out to examine possible baseline predictors of treatment effects at the 3-month assessment.

RESULTS

Results were available for 395 patients at 3-month assessment. According to the EULAR response criteria 42 patients failed to show at least a moderate response. After adjusting for confounders using multivariate analysis, current smoking at the time of commencing an anti-TNF-alpha agent reduced the chance of achieving at least a moderate response on the EULAR response criteria when compared with nonsmokers (aOR [95% CI] 0.20 [0.05-0.83], P = 0.03).

CONCLUSIONS

RA patients who smoke are less likely to respond to an anti-TNF-alpha agent.

Effect of tobacco smoking on tissue protein citrullination and disease progression in patients with rheumatoid arthritis

The aim of the present work was to study the effect of tobacco smoking on disease progression in rheumatoid arthritis patients and its relation to anti-cyclical citrullinated peptide (anti-CCP) antibodies. The study included 54 patients; 20 non-smokers, 9 ex-smokers, 14 mild to moderate smokers and 11 heavy smokers. Fifteen normal volunteers were also studied as controls. Disease stage was clinically and radiologically determined, rheumatoid factor (RF) and anti-CCP antibodies were measured in serum. Higher percentage of severe disease (stage III) was seen in heavy smoker patients than mild to moderate smokers (54.6% versus 35.7%) and in moderate smokers than ex-smokers (35.7% versus 33.6%). Lowest percentage of severe disease was seen in non-smokers (15%). RF and anti-CCP were significantly higher in smoker than non-smoker and in heavy than mild to moderate smoker patients (p < 0.01, p < 0.05 and p < 0.01, p < 0.001, respectively). In smoker patients, both RF and anti-CCP antibodies correlated significantly and positively with smoking index (r = 0.581, p < 0.001; r = 0.661, p < 0.001). Also, smoking index and anti-CCP correlated significantly and positively with disease stage (r = 0.424, p < 0.05; r = 0.523, p < 0.01). It appears from our results that, tobacco smoking mostly play a role in progression of rheumatoid arthritis through tissue protein citrullination. So all rheumatoid arthritis patients must quit completely to achieve a good control.

Levels of anti-citrullinated protein antibodies and IgM rheumatoid factor are not associated with outcome in early arthritis patients: a cohort study

Introduction

To investigate whether baseline levels of anti-citrullinated protein antibody (ACPA) or IgM rheumatoid factor (IgM-RF) and changes in the year thereafter are associated with disease activity, functional and radiographic outcome in early arthritis patients, and provide additional information over baseline autoantibody status.

Methods

In 545 early arthritis patients ACPA and IgM-RF levels, disease activity (DAS28), the Health Assessment Questionnaire (HAQ) and Sharp/Van der Heijde Score (SHS) were assessed annually. Baseline status, levels and first-year changes of the autoantibodies were associated with these measures at the two-year follow-up and sub-analysed according to autoantibody status.

Results

The mean age was 52.7 years, 69% was female, at baseline 56% was ACPA positive, 47% IgM-RF positive. At the two-year follow-up the mean DAS28 was 2.88, and the median HAQ and SHS were 0.38 and 1, respectively. At one year, ACPA and IgM-RF levels had decreased by 31% and 56%, respectively. A switch from negative to positive occurred in 2% for ACPA and 3% for IgM-RF. Positive ACPA and RF status were both associated with SHS at two years (P < 0.001), but baseline levels only showed a minor correlation of ACPA with DAS28 and HAQ at two years. Level changes were not associated with the outcome parameters.

Conclusions

Baseline levels and first-year changes of ACPA and IgM-RF are hardly associated with outcome after two years. Seroconversion seldom occurs. Therefore, it does not appear useful to repeat ACPA or IgM-RF measurements.

Effects of tobacco smoke on immunity, inflammation and autoimmunity

Smoking is a central factor in many pathological conditions. Its role in neoplasm, lung and cardiovascular diseases has been well established for years. However it is less acknowledged the cigarette smoking affects both the innate and adoptive immune arms. Cigarette smoke was shown to augment the production of numerous pro-inflammatory cytokines such as TNF-alpha, IL-1, IL-6, IL-8 GM-CSF and to decrease the levels of anti-inflammatory cytokines such as IL-10. Tobacco smoke via multiple mechanisms leads to elevated IgE concentrations and to the subsequent development of atopic diseases and asthma. Cigarette smoke has also been shown activate in many ways macrophage and dendritic cell activity. While it is better evident how cigarette smoke evokes airway diseases more mechanisms are being revealed linking this social hazard to autoimmune disorders, for instance via the production of antibodies recognizing citrullinated proteins in rheumatoid arthritis or by the elevation of anti-dsDNA titers in systemic lupus erythematosus. The current review underlines the importance of smoking prevention and eradication not only in respiratory disorders but also in autoimmune conditions as well.

Rheumatoid arthritis: Disease or syndrome?

Rheumatoid arthritis (RA) has been described in the medical literature for over two hundred years, but its etiology remains unknown. RA displays phenotypic heterogeneity, and it is a relatively prevalent clinical entity: it affects approximately 1% of the population, resulting in enormous pathologic sequelae. Earlier studies targeting the cause(s) of RA suggested potential infectious involvement, whereas more recent reports have focused on a genetic origin of the disease. However, neither infection nor genetics, nor any other single factor is currently accepted as causative of RA. In this article we review studies relating to the etiology of RA, and those of several related matters, and we conclude that the literature indeed does provide insight into the causes underlying the initiation of RA pathogenesis. Briefly, given the remarkable phenotypic variation of RA, especially in its early stages, as well as a number of other characteristics of the condition, we contend that RA is not a discrete clinical entity with a single etiological source. Rather, we argue that it represents a common clinical endpoint for various starting points, each of which is largely guided by as yet poorly understood aspects of the genetic background of the affected individual. Adoption of this alternative view of the origin of RA will have significant consequences for future research and for development of new therapeutic interventions for this burdensome condition.

Rheumatoid arthritis and smoking: putting the pieces together

Besides atherosclerosis and lung cancer, smoking is considered to play a major role in the pathogenesis of autoimmune diseases. It has long been known that there is a connection between rheumatoid factor-positive rheumatoid arthritis and cigarette smoking. Recently, an important gene-environment interaction has been revealed; that is, carrying specific HLA-DRB1 alleles encoding the shared epitope and smoking establish a significant risk for anti-citrullinated protein antibody-positive rheumatoid arthritis. We summarize how smoking-related alteration of the cytokine balance, the increased risk of infections (the possibility of cross-reactivity) and modifications of autoantigens by citrullination may contribute to the development of rheumatoid arthritis.

Different properties of ACPA and IgM-RF derived from a large dataset: further evidence of two distinct autoantibody systems

Introduction

The aim of this study was to examine seroconversion and the relationship with age and inflammation of autoantibodies in a large group of patients attending an outpatient rheumatology clinic.

Methods

Levels of antibodies to citrullinated proteins/peptides (ACPAs) and IgM rheumatoid factor (IgM-RF) were determined in 22,427 samples collected from 18,658 patients. The diagnosis was derived from a diagnosis registration system. The degree of seroconversion in repeated samples and the correlation of levels with age and inflammatory markers were determined for ACPA and IgM-RF in rheumatoid arthritis (RA) and non-RA patients.

Results

Seventy-one percent of RA patients (n = 1,524) were ACPA-positive and 53% were IgM-RF-positive; in non-RA patients (n = 2,245), the corresponding values were 2% and 4%, respectively. In patients with at least two samples (n = 3,769), ACPA status was more stable than IgM-RF status in RA patients. ACPA- or IgM-RF-negative non-RA patients seldom became positive. ACPA positivity was unrelated to age in both RA and non-RA patients. IgM-RF positivity was unrelated to age in RA patients; however, it increased with age in non-RA patients. The correlation between autoantibody levels and inflammatory markers was low in general and was somewhat higher for IgM-RF than for ACPA.

Conclusions

ACPA status is more stable in time and with increasing age than IgM-RF status, further establishing its role as a disease-specific marker. ACPA and IgM-RF levels are only moderately correlated with markers of inflammation.