Update on Biomarkers in Psoriatic Arthritis

CCR4+ CD8+ T cells clonally expand to differentiated effectors in murine psoriasis and in human psoriatic arthritis

Psoriasis is a chronic inflammatory skin disease with an autoimmune component and associated with joint inflammation in up to 30% of cases. To investigate autoreactive T cells, we developed an imiquimod-induced psoriasis-like inflammation model in K5-mOVA.tg C57BL/6 mice expressing ovalbumin (OVA) on the keratinocyte membrane, adoptively transferred with OT-I OVA-specific CD8⁺ T cells. We evaluated the expansion of OT-I CD8⁺ T cells and their localization in skin, blood, and spleen. scRNA-seq and TCR sequencing data from patients with psoriatic arthritis were also analyzed. In the imiquimod-treated K5-mOVA.tg mouse model, OT-I T cells were markedly expanded in the skin and blood at early time points. OT-I T cells in the skin showed mainly CXCR3⁺ effector memory phenotype, whereas in peripheral blood there was an expansion of CCR4⁺ CXCR3⁺ OT-I cells. At a later time point, expanded OVA-specific T-cell population was found in the spleen. In patients with psoriatic arthritis, scRNA-seq and TCR sequencing data showed clonal expansion of CCR4⁺ T_CM cells in the circulation and further expansion in the synovial fluid. Importantly, there was a clonotype overlap between CCR4⁺ T_CM in the peripheral blood and CD8⁺ T-cell effectors in the synovial fluid. This mechanism could play a role in the generation and spreading of autoreactive T cells to the synovioentheseal tissues in psoriasis patients at risk of developing psoriatic arthritis.

Matrix Metalloproteinases; A Biomarker of Disease Activity and Prognosis in Spondyloarthritis: A Narrative Review

BACKGROUND

Matrix metalloproteinases, as components of the proteolytic system, are deemed to be implicated in the pathogenesis and progression of several rheumatic diseases. Their role in spondyloarthritis has been investigated by several studies.

OBJECTIVE

This article aims to review and summarize the current knowledge related to metalloproteinases in patients with spondyloarthritis.

METHODS

To examine the association between matrix metalloproteinases and spondyloarthritis, we conducted a narrative review using a literature search in SCOPUS for English-language sources. The search included studies published from the database inception to December 2020.

RESULTS

A total number of 74 articles were included. It was found that levels of matrix metalloproteinases 3 were higher in radiographic axial spondyloarthritis patients and seemed to play a role in the progression of joint damage. The levels of matrix metalloproteinases 1, 2, and 9 were upregulated in psoriatic arthritis patients compared to psoriasis and could identify psoriasis patients who would develop rheumatic manifestations. The levels of matrix metalloproteinases correlated significantly with disease activity in ankylosing spondylitis and decreased upon treatment with Tumor Necrosis Factor inhibitors (TNFi).

CONCLUSION

Excessive matrix metalloproteinases activity is associated with articular destruction. Their levels can reflect disease activity, structural damage, and response to TNFi in patients with spondyloarthritis. Nevertheless, further studies are needed to confirm these results.

Bone phenotypes in rheumatology - there is more to bone than just bone

Osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, all have one clear common denominator; an altered turnover of bone. However, this may be more complex than a simple change in bone matrix and mineral turnover. While these diseases share a common tissue axis, their manifestations in the area of pathology are highly diverse, ranging from sclerosis to erosion of bone in different regions. The management of these diseases will benefit from a deeper understanding of the local versus systemic effects, the relation to the equilibrium of the bone balance (i.e., bone formation versus bone resorption), and the physiological and pathophysiological phenotypes of the cells involved (e.g., osteoblasts, osteoclasts, osteocytes and chondrocytes). For example, the process of endochondral bone formation in chondrocytes occurs exists during skeletal development and healthy conditions, but also in pathological conditions. This review focuses on the complex molecular and cellular taxonomy of bone in the context of rheumatological diseases that alter bone matrix composition and maintenance, giving rise to different bone turnover phenotypes, and how biomarkers (biochemical markers) can be applied to potentially describe specific bone phenotypic tissue profiles.

Increased frequency of activated CD8+ T cell effectors in patients with psoriatic arthritis

The aim of this study is to identify subsets of T cells differentially represented in the circulation of patients with psoriatic arthritis and to evaluate the possibility that they can recirculate between peripheral blood and the inflamed joints. We analyzed the phenotype and cytokine expression in circulating CD8+ and CD4+ T cells in 69 subjects: 28 with cutaneous psoriasis, 15 patients with psoriatic arthritis, and 26 healthy subjects. In the circulation, the percentage of each subset was compared among the groups and correlation was calculated with the serum concentration of C-reactive protein. To investigate the migration of T cells towards the inflamed joints, we performed a transwell migration assay towards patient serum and synovial fluid. In selected patients we analyzed in parallel T cells from peripheral blood and from synovial fluid. In the circulation, we found increased percentage of CD8+ CCR6+ T cell effectors expressing CD69 and of IL-17-producing T cells in patients with psoriatic arthritis. CD8+ effector/effector memory T cells showed increased migration towards synovial fluid. Finally, in synovial fluid we found accumulation of CXCR3+ CD8+ T cells and CD69+ cells. CD4+ T cells in the two compartments shared many similarities with CD8+ T cells. The results indicate a role for memory T cell effectors in systemic and joint manifestations of psoriatic arthritis.

Differentiating Psoriatic Arthritis From Psoriasis Without Psoriatic Arthritis Using Novel Serum Biomarkers

OBJECTIVE

There is a high prevalence of undiagnosed psoriatic arthritis (PsA) in patients with psoriasis. Identifying soluble biomarkers for PsA will help in screening psoriasis patients for appropriate rheumatology referral. We therefore aimed to investigate whether serum levels of novel markers previously discovered by quantitative mass spectrometric analysis of synovial fluid and skin biopsies performs better than the C-reactive protein (CRP) level in differentiating PsA patients from those with psoriasis without PsA (PsC).

METHODS

In this case-control study, serum samples were obtained from 100 subjects with PsA, 100 with PsC, and 100 healthy controls. Patients with PsA and PsC were group matched for age, sex, psoriasis duration, and Psoriasis Area and Severity Index and were not currently receiving biologic treatment. Using enzyme-linked immunosorbent assay, 4 high-priority markers (Mac-2-binding protein [M2BP], CD5-like protein [CD5L], myeloperoxidase [MPO], and integrin β5 [ITGβ5]), as well as previously established markers (matrix metalloproteinase 3 [MMP-3] and CRP level) were assayed. Data were analyzed using logistic regression. Receiver operating characteristic (ROC) curves were plotted.

RESULTS

In comparisons to controls, CD5L, ITGβ5, M2BP, MPO, MMP-3, and CRP level were independently associated with PsA, while only CD5L, M2BP, and MPO were independently associated with PsC alone. In comparisons to PsC, ITGβ5, M2BP, and CRP level were independently associated with PsA. ROC analysis of this model shows an area under the curve (AUC) of 0.85 (95% confidence interval [95% CI] 0.80-0.90). The model that included CRP level alone had an AUC of 0.71 (95% CI 0.64-0.78).

CONCLUSION

CD5L, ITGβ5, M2BP, MPO, MMP-3, and CRP level are markers for PsA. The combination of ITGβ5, M2BP, and CRP level differentiates PsA from PsC, and performs better than CRP level alone.

Therapeutic strategies utilization and resource consumption in patients treated for psoriatic arthritis: findings from a real-world analysis in an Italian setting

PURPOSE

The purpose of this study was to analyze the therapeutic strategies and estimate the health care resource consumption in patients with psoriatic arthritis (PsA).

PATIENTS AND METHODS

An observational retrospective cohort analysis of administrative databases of six Italian Local Health Units was performed. Patients ≥18 years with a hospitalization discharge diagnosis of PsA (International Classification of Diseases, Ninth Revision code: 696.0) or exemption code (045.696.0) for PsA from January 1, 2010 to December 31, 2015 (inclusion period), with at least one prescription of any therapy used for PsA were included. The index date (ID) was the first date matching with at least one of the inclusion criteria during the inclusion period. All patients were followed up after the ID until the end of data availability. Baseline C-reactive protein (CRP) levels (±6 months in relation to the ID) were also analyzed.

RESULTS

A total of 2,408 (prevalence 0.83 per 1,000) patients with PsA (male 52%; median age 54 years) were included in the study; patients were already treated for PsA in 42.4% of cases. At 1 year of follow-up, 73% of the patients received one systemic drug, while 22% of patients received two systemic drugs; in addition, our results show an increase in the number of add-on or switches in a longer follow-up period. The utilization of biologic agents was higher among patients with previous PsA treatment, showing a progression of the pathology. Overall, a medium/high level of CRP at baseline was observed among more than half of the overall sample, with slight changes across subgroups in analysis. The average health care costs were €1,966.4 and €13,914 per year for patients treated with conventional systemic therapy and biological agents, respectively.

CONCLUSION

A better knowledge of prescription therapeutic scheme and economic burden of PsA could stimulate the rational development of health programs aimed at potentiating services for its management.

T Cell Hierarchy in the Pathogenesis of Psoriasis and Associated Cardiovascular Comorbidities

The key role of T cells in the pathogenesis of cutaneous psoriasis has been well described in the last decade and the knowledge of the relative role of the different subsets of T cells in psoriasis pathogenesis has considerably evolved. Now, it is clear that IL-17A-producing T cells, including Th17/Tc17, have a central role in the pathogenesis of cutaneous psoriasis and therapies blocking the IL-17A pathway show high clinical efficacy. By contrast, the contribution of IFNγ-producing T cells has progressively become less clear because of the lack of efficacy of anti-IFNγ antibodies in clinical studies. In parallel, the role of CD8⁺ T cells specific for self-antigens has been revived and increasing evidence now indicates that in psoriatic skin the majority CD8⁺ T cells are present in the form of epidermal tissue-resident memory T cells. In the last years it also emerged the possibility of a contribution of T cell recirculation in the pathogenesis of psoriasis and its systemic manifestations. The aim of this review is to define a hierarchy for the different subsets of T cells in the T cell-mediated inflammatory cascade in psoriatic skin. This analysis will possibly help to distinguish the subsets that initiate the disease, those involved in the establishment of the self-sustaining amplification loop that leads to the cutaneous clinical manifestations and finally the subsets that act as downstream players in established lesions. Specific T cell subpopulations finally will be considered for their possible role in propagating inflammation at distant sites and for representing a link with systemic inflammation and cardiovascular comorbidities.

S100A8/A9, a potent serum and molecular imaging biomarker for synovial inflammation and joint destruction in seronegative experimental arthritis

Background

Seronegative joint diseases are characterized by a lack of well-defined biomarkers since autoantibodies are not elevated. Calprotectin (S100A8/A9) is a damage-associated molecular pattern (DAMP) which is released by activated phagocytes, and high levels are found in seronegative arthritides. In this study, we investigated the biomarker potential of systemic and local levels of these S100 proteins to assess joint inflammation and joint destruction in an experimental model for seronegative arthritis.

Methods

Serum levels of S100A8/A9 and various cytokines were monitored during disease development in interleukin-1 receptor antagonist (IL-1Ra)^–/– mice using ELISA and multiplex bead-based immunoassay, and were correlated to macroscopic and microscopic parameters for joint inflammation, bone erosion, and cartilage damage. Local expression of S100A8 and S100A9 and matrix metalloproteinase (MMP)-mediated cartilage damage in the ankle joints were investigated by immunohistochemistry. In addition, local S100A8 and activated MMPs were monitored in vivo by optical imaging using anti-S100A8-Cy7 and AF489-Cy5.5, a specific tracer for activated MMPs.

Results

Serum levels of S100A8/A9 were significantly increased in IL-1Ra^–/– mice and correlated with macroscopic joint swelling and histological inflammation, while serum levels of pro-inflammatory cytokines did not correlate with joint swelling. In addition, early serum S100A8/A9 levels were prognostic for disease outcome at a later stage. The increased serum S100A8/A9 levels were reflected by an increased expression of S100A8 and S100A9 within the ankle joint, as visualized by molecular imaging. Next to inflammatory processes, serum S100A8/A9 also correlated with histological parameters for bone erosion and cartilage damage. In addition, arthritic IL-1Ra^–/– mice with increased synovial S100A8 and S100A9 expression showed increased cartilage damage that coincided with MMP-mediated neoepitope expression and in vivo imaging of activated MMPs.

Conclusions

Expression of S100A8 and S100A9 in IL-1Ra^–/– mice strongly correlates with synovial inflammation, bone erosion, and cartilage damage, underlining the potential of S100A8/A9 as a systemic and local biomarker in seronegative arthritis not only for assessing inflammation but also for assessing severity of inflammatory joint destruction.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1121-z) contains supplementary material, which is available to authorized users.

T cell responses in psoriasis and psoriatic arthritis

According to the current view the histological features of psoriasis arise as a consequence of the interplay between T cells, dendritic cells and keratinocytes giving rise to a self-perpetuating loop that amplifies and sustains inflammation in lesional skin. In particular, myeloid dendritic cell secretion of IL-23 and IL-12 activates IL-17-producing T cells, Th22 and Th1 cells, leading to the production of inflammatory cytokines such as IL-17, IFN-γ, TNF and IL-22. These cytokines mediate effects on keratinocytes thus establishing the inflammatory loop. Unlike psoriasis the immunopathogenic features of psoriatic arthritis are poorly characterized and there is a gap in the knowledge of the pathogenic link between inflammatory T cell responses arising in the skin and the development of joint inflammation. Here we review the knowledge accumulated over the years from the early evidence of autoreactive CD8 T cells that was studied mainly in the years 1990s and 2000s to the recent findings of the role of Th17, Tc17 cells and γδ T cells in psoriatic disease pathogenesis. The review will also focus on common and distinguishing features of T cell responses in psoriatic plaques and in synovial fluid of patients with psoriatic arthritis. The integration of this information could help to distinguish the role played by T cells in the initiation phase of the disease from the role of T cells as downstream effectors sustaining inflammation in psoriatic plaques and potentially leading to disease manifestation in distant joints.

Serum kallikrein-8 correlates with skin activity, but not psoriatic arthritis, in patients with psoriatic disease

BACKGROUND

About 30% of cutaneous psoriasis (PsC) patients develop psoriatic arthritis (PsA) in the joint, which is under-recognized by dermatologists. Biomarkers for PsA are needed so that early referral to a rheumatologist is made. Kallikreins (KLKs) are secreted serine proteases implicated in skin desquamation and inflammation. This study examined KLK potential as serum biomarkers of PsA in cutaneous psoriasis patients.

METHODS

KLKs were measured by ELISAs in synovial fluids of three PsA patients and three control early osteoarthritis (OA) patients, as well as in a cohort of 152 serum samples collected from age- and sex-matched PsC patients, with (n=76) or without PsA (n=76). KLK expression in psoriatic plaques was examined by immunohistochemistry. Univariate and multivariate logistic regression analyses were conducted to analyze the association between serum KLK levels and disease class (PsC, PsA). Serum KLKs that associated with PsA were correlated with clinical parameters of skin and joint activity.

RESULTS

Among the seven KLKs tested, KLK6 and KLK8 were elevated in both PsA synovial fluids and psoriatic plaques, but only serum KLK8 levels were associated with psoriatic disease (odds ratio=2.56, p=0.03). Although significantly elevated in PsC and PsA sera compared to healthy controls, KLK8 did not discriminate PsA from PsC patients. KLK8 correlated positively with the psoriasis area and severity index (PASI) (r=0.43, p=0.001) independent of age, sex and psoriasis duration ( β=1.153, p=0.0003) and exhibited no correlations with tender or swollen joint counts.

CONCLUSIONS

Increased KLK8 serum level in PsA patients reflects disease activity in the skin but not in the joints. Serum KLK levels are not useful for screening psoriasis patients for PsA.

Analysis of mass spectrometry data from the secretome of an explant model of articular cartilage exposed to pro-inflammatory and anti-inflammatory stimuli using machine learning

BACKGROUND

Osteoarthritis (OA) is an inflammatory disease of synovial joints involving the loss and degeneration of articular cartilage. The gold standard for evaluating cartilage loss in OA is the measurement of joint space width on standard radiographs. However, in most cases the diagnosis is made well after the onset of the disease, when the symptoms are well established. Identification of early biomarkers of OA can facilitate earlier diagnosis, improve disease monitoring and predict responses to therapeutic interventions.

METHODS

This study describes the bioinformatic analysis of data generated from high throughput proteomics for identification of potential biomarkers of OA. The mass spectrometry data was generated using a canine explant model of articular cartilage treated with the pro-inflammatory cytokine interleukin 1 β (IL-1β). The bioinformatics analysis involved the application of machine learning and network analysis to the proteomic mass spectrometry data. A rule based machine learning technique, BioHEL, was used to create a model that classified the samples into their relevant treatment groups by identifying those proteins that separated samples into their respective groups. The proteins identified were considered to be potential biomarkers. Protein networks were also generated; from these networks, proteins pivotal to the classification were identified.

RESULTS

BioHEL correctly classified eighteen out of twenty-three samples, giving a classification accuracy of 78.3% for the dataset. The dataset included the four classes of control, IL-1β, carprofen, and IL-1β and carprofen together. This exceeded the other machine learners that were used for a comparison, on the same dataset, with the exception of another rule-based method, JRip, which performed equally well. The proteins that were most frequently used in rules generated by BioHEL were found to include a number of relevant proteins including matrix metalloproteinase 3, interleukin 8 and matrix gla protein.

CONCLUSIONS

Using this protocol, combining an in vitro model of OA with bioinformatics analysis, a number of relevant extracellular matrix proteins were identified, thereby supporting the application of these bioinformatics tools for analysis of proteomic data from in vitro models of cartilage degradation.

C-reactive protein in psoriasis: a review of the literature

A great deal of research has addressed the elevation of C-reactive protein (CRP) among psoriatic patients and the role of this marker in assessment of disease severity and progression. However, there are some discrepancies in this area. We sought to figure out the relationship between CRP values and disease severity as well as the changes in marker levels after treatment through an extensive literature review. Comparison between CRP levels in psoriatic patients and those in healthy or non-psoriatic individuals was also another focus of this review. A thorough search in Pubmed and Embase was conducted for articles investigating different aspects of CRP measurement in patients with psoriasis. Overall, 32 articles were found to meet our inclusion criteria. Of 28 studies comparing the CRP values in psoriatic patients with those of controls, 24 found a statistically significant difference. In addition, 12 out of 16 papers examining the association between disease severity and CRP values noted significant results. With regard to CRP changes over the course of a treatment, all 15 studies addressing this issue revealed a significant decrease in marker levels. In conclusion, high CRP levels only for moderate and severe forms of disease might be inferred from the literature and there is no sufficient evidence suggesting a similar association for mild disease as well. Moreover, CRP may serve interchangeably with Psoriasis Area and Severity Index (PASI) as a measure of disease severity in the case of untreated psoriatic patients who do not have disease related arthritis. For other patients, however, a careful clinical examination and PASI calculation still remain the mainstay of severity assessment.

Soluble Biomarkers Associated with Response to Treatment with Tumor Necrosis Factor Inhibitors in Psoriatic Arthritis

Objective.

To identify soluble biomarkers associated with response to therapy with tumor necrosis factor inhibitors (TNFi) in patients with psoriatic arthritis (PsA).

Methods.

The study was conducted at a PsA clinic where patients are assessed every 6 months, and serum samples are collected and stored once a year at the time of clinical assessment. Forty patients with active PsA who gave serum samples prior to treatment with TNFi and after at least 3 months of therapy were identified. Patients were classified as TNFi responders if tender joint count was < 3, swollen joint count was 0, and Psoriasis Area and Severity Index score was < 4 at the time the second sample was collected. The following biomarkers were tested by ELISA: TNF superfamily 14, matrix metalloprotease-3 (MMP-3), receptor activator of nuclear factor kappa-B ligand, osteoprotegerin, cartilage oligomeric matrix protein (COMP), CPII, C2C and C1-2C, CS-846, and highly sensitive C-reactive protein. Paired t tests and logistic regression was used for statistical analyses.

Results.

After a mean treatment duration of 11 months with TNFi (etanercept 28 patients, adalimumab 6, golimumab 4, infliximab 2), 29 patients were classified as TNFi responders. Baseline level of MMP-3 was independently associated with responder status (OR 1.067 for each 1-unit increase, p = 0.045). A reduction in MMP-3 levels with therapy increased the odds of achieving response (OR 1.213 for each 1-unit change, p = 0.030), whereas a reduction in COMP decreased the odds (OR 0.587, for each 100-unit increase, p = 0.039). None of the other biomarkers was associated with response.

Conclusion.

Baseline as well as reduction in serum MMP-3 and increase in serum COMP are independently associated with response to TNFi therapy in patients with PsA.

Spondyloarthropathies

Spondyloarthropathies (SpA) are a group of common inflammatory rheumatic disorders characterised by axial and or peripheral arthritis, associated with enthesitis, dactylitis and potential extra-articular manifestations such as uveitis and skin rash. The diseases, which comprise the group, share a common genetic predisposition, the HLA-B27 gene; however, this association varies markedly among the various SpAs and among different ethnic groups. Environmental factors seem to be triggering the diseases in the genetically predisposed individuals. The radiographic hallmark of the group is sacroiliitis, which when present is of help in the diagnosis. Various sets of diagnostic and classification criteria were developed over the years including the European Spondyloarthropathy Study Group (ESSG) criteria which were until recently the most widely used. The new Assessment in SpondyloArthritis international Society (ASAS) international working group has recently proposed a new set of diagnostic criteria that would enable identification of SpA before structural changes develop in the spine. Magnetic resonance imaging (MRI) changes have now been included in the new classification criteria of early axial SpA and are now considered as a major tool in the diagnosis. Until recently, there were no real disease-modifying anti-rheumatic drugs which were able to halt the disease progression. Over the past decade, tumour necrosis factor (TNF)-alfa-blocking agents have been extensively investigated and became the mainstream of therapy providing the patients an effective treatment option.

How can psoriatic arthritis be diagnosed early?

Psoriatic arthritis (PsA) is an inflammatory arthritis that usually develops after the onset of cutaneous psoriasis. Early diagnosis of PsA may lead to less joint damage and better long-term outcomes. Identifying inflammatory arthritis in individuals with psoriasis is the key to early diagnosis of PsA. Screening strategies targeted at individuals with psoriasis, as well as family members of patients with PsA will result in early identification of PsA. This article describes the various strategies that could be employed to identify inflammatory arthritis in patients with psoriasis so that appropriate referral to a rheumatologist for early diagnosis of PsA may be made.

[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.

[Psoriatic arthritis : a permanent challenge for rheumatologists and patients--Part 1: epidemiology, pathogenesis and clinical course]

Psoriatic arthritis is still one of the big challenges in rheumatology due to the great variety of symptoms. Treatment frequently requires an interdisciplinary collaboration of general practitioners, dermatologists and rheumatologists who are able to recognize the onset of disease early by means of classification criteria and new imaging techniques followed by the implementation of appropriate antirheumatic treatment. During recent years new immunological pathways have been discovered leading to an increasing number of potential therapies, which increases the chance to find effective individualized treatment. However, tracking back the onset of the disease to specific causes is still a challenge which is made even more complex due to the absence of specific serum parameters.