The Conundrum of Psoriatic Arthritis: a Pathogenetic and Clinical Pattern at the Midpoint of Autoinflammation and Autoimmunity

Psoriatic arthritis (PsA) is a chronic inflammatory condition characterized by psoriasis, synovitis, enthesitis, spondylitis, and the possible association with other extra-articular manifestations and comorbidities. It is a multifaceted and systemic disorder sustained by complex pathogenesis, combining aspects of autoinflammation and autoimmunity. Features of PsA autoinflammation include the role of biomechanical stress in the onset and/or exacerbation of the disease; the evidence of involvement of the innate immune response mediators in the skin, peripheral blood and synovial tissue; an equal gender distribution; the clinical course which may encounter periods of prolonged remission and overlapping features with autoinflammatory syndromes. Conversely, the role of autoimmunity is evoked by the association with class I major histocompatibility complex alleles, the polyarticular pattern of the disease which sometimes resembles rheumatoid arthritis and the presence of serum autoantibodies. Genetics also provide important insights into the pathogenesis of PsA, particularly related to class I HLA being associated with psoriasis and PsA. In this review, we provide a comprehensive review of the pathogenesis, genetics and clinical features of PsA that endorse the mixed nature of a disorder at the crossroads of autoinflammation and autoimmunity.

Autoantibodies in psoriatic disease

Psoriasis is an inflammatory skin disease affecting over 8 million people in the US and Canada. Approximately, a quarter of psoriasis patients have an inflammatory arthritis termed psoriatic arthritis (PsA). Psoriatic disease encompassing both psoriasis and PsA is regarded as an immune-mediated inflammatory disease, exhibiting both autoimmune and autoinflammatory features. A review of the current literature on the presence and clinical significance of autoantibodies found in psoriatic disease are presented. The frequency of several autoantibodies in psoriasis and PsA patients as well as their clinical significance regarding disease diagnosis, disease activity and treatment response are reviewed. Additionally, the basic principles of antibody assays are presented, and the methods used for each study are analyzed. Despite historically described as a rheumatoid factor negative (seronegative) disease, an array of autoantibodies has been identified in patients with psoriatic disease. This points to an autoimmune component potentially playing a role in psoriatic disease; however, additional evidence is needed to determine the clinical utility of these autoantibodies.

Anti-cyclic-citrullinated-protein-antibodies in psoriatic arthritis patients: how autoimmune dysregulation could affect clinical characteristics, retention rate of methotrexate monotherapy and first line biotechnological drug survival. A single center retrospective study

AIM

Occasional findings of anti-cyclic-citrullinated-protein-antibodies (anti-CCP) were rarely observed in psoriatic arthritis (PsA). The aim of our study is to evaluate whether the presence of anti-CCP can determine different clinical subsets and influence methotrexate monotherapy survival, and biotechnological drug retention rate.

METHODS

We conducted a retrospective study on PsA patients. All patients were required to fulfill the CASPAR criteria for PsA, and to present juxta-articular osteo-proliferative signs at X-ray. The exclusion criteria were age less than 18 years old, satisfaction of rheumatoid arthritis classification criteria, and seropositivity for rheumatoid factor. Clinical characteristics, anti-CCP titer, drug survival and comorbidities information were recorded for each patient. Statistical significance was set at p ⩽ 0.05.

RESULTS

Of 407 patients with PsA screened 113 were recruited. Twelve patients were anti-CCP positive. Methotrexate monotherapy survival was shorter in patients with anti-CCP (150 ± 48.3 weeks versus 535.3 ± 65.3 weeks; p = 0.026) [discontinuation risk hazard ratio (HR) = 2.389, 95% confidence interval (CI) 1.043, 5.473; p = 0.039] than those without. Significant shorter survival of first-line biotechnological drugs (b-DMARDs) was observed in the anti-CCP positive group than in that without (102.05 ± 24.4 weeks versus 271.6 ± 41.7 weeks; p = 0.005) with higher discontinuation risk (HR = 3.230, 95% CI 1.299, 8.028; p = 0.012). A significant higher rate of multi-failure (more than second-line b-DMARDs) was found in anti-CCP positive patients than in those without (50% versus 14%, p = 0.035).

CONCLUSION

Anti-CCP in PsA could be suggestive of more severe disease, with worse drug survival of both methotrexate monotherapy and first-line b-DMARDs, and higher chance to be b-DMARDs multi-failure. So, they can be considered for more intensive clinical management of these patients.

Anti-cyclic citrullinated peptide antibody in psoriatic arthritis: a meta-analysis of its frequency and association with clinical features

OBJECTIVE

This study aimed to investigate the frequency of the anti-cyclic citrullinated peptide (anti-CCP) antibody in patients with psoriatic arthritis (PsA) and to assess its associations with clinical features of this disease.

METHODS

The Medline, EMBASE, and Cochrane databases were searched for studies that examined anti-CCP antibodies in patients with PsA. Meta-analyses of the frequency of the anti-CCP antibody in these patients and its association with polyarthritis, bone erosion, dactylitis, and enthesitis were then performed.

RESULTS

Fourteen studies with a combined total of 3291 patients with PsA met the inclusion criteria for this meta-analysis. The pooled overall frequency of anti-CCP antibodies was 9.8% (95% confidence interval [CI] = 7.1-13.3, p < 0.001). Stratification by ethnicity showed that the anti-CCP antibody frequency was lower in Europeans than in non-Europeans (8.5% vs. 14.0%). The meta-analysis showed a significant association of the anti-CCP antibody with polyarthritis (odds ratio [OR] = 4.390, 95% CI = 2.312-8.333, p < 0.001), bone erosion (OR = 2.800, 95% CI = 1.921-4.081, p < 0.001), and dactylitis (OR = 1.958, 95% CI = 1.340-2.861, p < 0.001). However, there was no association between this antibody and enthesitis.

CONCLUSIONS

Our meta-analysis demonstrated that the overall frequency of the anti-CCP antibody was 9.8% in patients with PsA, and its presence was associated with increased risks of polyarthritis, bone erosion, and dactylitis, but not of enthesitis.

Consensus on the management of patients with psoriatic arthritis in a dermatology setting

BACKGROUND

Psoriatic arthritis (PsA) is a chronic inflammatory disease associated with psoriasis (PsO). Early diagnosis and prompt therapeutic intervention are crucial for limiting PsA progression and prevention of disability. Dermatologists are in a privileged position to detect early PsA. The management of patients with PsA in the dermatology setting is widely variable.

OBJECTIVE

To provide practical recommendations for the management of patients with PsA in the dermatology setting including early diagnosis and treatment.

METHODS

A consensus document was written by an expert panel composed by dermatologists (n = 12) and rheumatologists (n = 6). Eleven highly relevant questions were selected and elaborated with answers/statements based on a narrative literature review. The resulting document was discussed in a face-to-face meeting adopting a nominal group technique to reach consensus (i.e. 100% agreement) using the Delphi method.

RESULTS

A consensus was achieved in defining the following: the clinical characteristics differentiating inflammatory and non-inflammatory signs and symptoms of joint disease; the most important differential diagnoses of PsA in clinical practice; the most useful screening questionnaires, serum laboratory tests and imaging techniques for the detection of early PsA; the criteria for dermatologist to refer patients with PsO to rheumatologist; the criteria for the diagnosis of PsA; the selection of the indices that the dermatologist could use for measuring the activity and severity of PsA in clinical practice; when systemic steroids and/or intra-articular steroid injections are indicated in the treatment of PsA. Finally, systemic treatments including synthetic and biologic disease-modifying antirheumatic drugs to be considered for the treatment of PsA have been reported.

CONCLUSIONS

The implementations of these practical recommendations could be very helpful for the management of patients with PsA in the dermatology setting including early diagnosis and treatment.

Significance of Anti-cyclic Citrullinated Peptide Autoantibodies in Immune-mediated Inflammatory Skin Disorders with and without Arthritis

Background:

Anti-cyclic citrullinated peptides (CCPs) are autoantibodies directed against citrullinated peptides. Rheumatoid factor (RF), an antibody against the Fc portion of IgG, is known to form immune complexes and contribute to the etiopathogenesis of various skin disorders. C-reactive protein (CRP), an acute-phase protein, increases following secretion of interleukin-6 from macrophages and T cells. Anti-CCP, RF, and CRP are well-established immune-markers, their diagnostic potential in immune-mediated skin disorders remains less widely studied.

Aims and Objectives:

To determine the correlation between anti-CCP, RF, and CRP in immune-mediated inflammatory skin diseases.

Materials and Methods:

About 61 clinically diagnosed cases of various immune-mediated skin diseases (psoriasis [n = 38], connective tissue diseases such as systemic lupus erythematosus and systemic sclerosis [n = 14], and immunobullous disorders including pemphigus vulgaris and pemphigus foliaceus [n = 9]) were included in the study. These patients were subclassified on the basis of presence or absence of arthritis. Arthritis was present in nine cases of psoriasis and seven connective tissue disorder patients. Detection of serum anti-CCP was done using enzyme-linked immunosorbent assay, whereas CRP and RF levels were detected using latex agglutination technique.

Results:

Of the 61 specimens, 14.75% had elevated serum anti-CCP levels. RF and CRP levels were elevated in 18.03% and 39.34% specimens, respectively. RF was elevated in 13.16% of inflammatory and 42.88% of connective tissue disorders, whereas anti-CCP was raised in 10.53% of inflammatory and 35.71% of connective tissue disorders. CRP positivity was highest in connective tissue disorders (50%), followed by 39.47% in inflammatory and 22.22% in immunobullous conditions. In none of the immunobullous patients, anti-CCP or RF levels were found to be elevated. Association of the presence of arthritis with elevated anti-CCP was found to be statistically significant.

Conclusions:

Although anti-CCP, RF, and CRP levels are valuable markers of chronic immune-mediated skin disorders, elaborate studies enrolling a larger number of patients are required to validate these diagnostic markers.

Progress in understanding and utilizing TNF-α inhibition for the treatment of psoriatic arthritis

The improved recognition of pathogenetic molecular mechanisms has led to the use of drugs targeting cytokines in different inflammatory arthropathies as well psoriatic arthritis (PsA). In particular, the progress in knowledge on tumor necrosis factor (TNF)-α in the pathogenesis of PsA has changed the therapeutic approach by use of direct and receptor cytokine antagonists. Currently, infliximab (IFX), adalimumab, etanercept, golimumab and certolizumab pegol represent the five anti-TNF-α available for the treatment of PsA. This review describes evidence on treatment aimed at neutralizing TNF-α in PsA patients, from the first study in 2000 until today, mainly derived from randomized clinical trials. In comparison with traditional therapies, anti-TNF-α agents have shown to have more efficacy both in treating clinical aspects, including enthesitis, dactylitis, joint pain and swelling, axial involvement, nail and skin lesions, and in reducing radiographic progression. Moreover, anti-TNF-α agents have been demonstrated to be reasonably safe in PsA, as confirmed by data derived by different registries.

Anticyclic Citrullinated Peptide Antibodies in Rheumatoid and Nonrheumatoid Rheumatic Disorders: Experience with 1162 Patients

Objective.

Anticyclic citrullinated peptide antibodies (anti-CCP) are considered specific markers of rheumatoid arthritis (RA) and have been included in the revised classification criteria for RA diagnosis. However, these antibodies have also been detected in patients with other types of chronic inflammatory rheumatism. Our objectives were to identify the prevalence of positive anti-CCP patients in non-RA diseases, to determine the diagnostic value of anti-CCP for the diagnosis of RA, to specify the clinical characteristics of non-RA patients positive for anti-CCP, and to determine the discriminatory value of the levels of anti-CCP in patients among the various diseases.

Methods.

We carried out an observational and descriptive study. All the determinations of anti-CCP requested by the 2 rheumatology departments at Cochin Hospital over a period of 18 months were analyzed. Such determinations were requested for 1162 patients in total. Anti-CCP levels were determined with the Euro Diagnostica ELISA kit, with values ≥ 25 U for this test being considered positive. The diagnosis of rheumatic conditions was the responsibility of the treating physician.

Results.

Anti-CCP antibodies were detected in 357 (30.7%) of the 1162 patients. The prevalence of anti-CCP was 292/417 (70.0%) in RA, 13/122 (10.6%) in patients with psoriatic arthritis, 13/62 (20.9%) in patients with unclassified rheumatism, 11/33 (33.3%) in patients with primary Sjögren syndrome, 5/30 (16.6%) in patients with systemic lupus erythematosus, 3/28 (10.7%) in patients with mixed connective tissue disorder, 3/36 (8.3%) in patients with systemic sclerosis, 7/44 (15.9%) in patients with juvenile arthritis, and 6/220 (2.7%) in patients with noninflammatory diseases. In the population of patients positive for anti-CCP, mean anti-CCP levels were 869.4 (± 978.4) U/ml, with no significant difference between RA [854.8 (± 959.8) U/ml] and any of the non-RA conditions [922.7 (± 1070.0) U/ml].

Conclusion.

Anti-CCP are a hallmark of RA, but may be observed in other inflammatory, systemic, or mechanical diseases. In this large cohort of patients, the presence of second-generation anti-CCP (anti-CCP2) antibodies is useful in diagnosing RA (70% sensitivity, 91.3% specificity), but examining the levels of these antibodies does not appear to offer further discriminatory power among patients who are anti-CCP2-positive.

[Psoriasis arthritis. An interdisciplinary challenge]

Psoriatic arthritis (PsA) is classified as a spondylarthropathy based on its clinical and serological characteristics. The clinical manifestations and the association with psoriasis or nail psoriasis have led, together with immunological characteristics, to a further differentiation. The pathophysiological and genetic understanding of this disease has advanced as a result of the development of new treatment strategies and targets in rheumatology and dermatology. Collaborative efforts and increasing multidisciplinary cooperation between rheumatologists and dermatologists have led to an increased awareness in early diagnosis and treatment. New treatment modalities have demonstrated significant efficacy in preventing radiologic progression resulting in amelioration of clinical symptoms, improvement of function and quality of life.

The role of antibodies in inflammatory arthritis

Inflammatory arthritis presents in a variety of diseases, from rheumatoid arthritis to hepatitis. Antibodies to autoantigens or to microbial constituents are commonly associated with these conditions. In some cases, the antibodies have diagnostic and prognostic relevance. It cannot as yet be determined definitively that any of them mediate joint damage, although the evidence from animal models indicates that this mechanism is likely. The purpose of this article is to give an overview of the spectrum of antibodies found in a variety of inflammatory arthritides. The relevant animal models are also discussed.