Associations between human leukocyte antigen C locus polymorphism and psoriatic arthritis in populations of European and Middle Eastern descent: a meta-analysis

Biomarkers in psoriatic arthritis: A meta-analysis and systematic review

Introduction

Psoriatic arthritis (PsA) is a chronic inflammatory disease that frequently develops in patients with psoriasis (PsO) but can also occur spontaneously. As a result, PsA diagnosis and treatment is commonly delayed, or even missed outright due to the manifold of clinical presentations that patients often experience. This inevitably results in progressive articular damage to axial and peripheral joints and entheses. As such, patients with PsA frequently experience reduced expectancy and quality of life due to disability. More recently, research has aimed to improve PsA diagnosis and prognosis by identifying novel disease biomarkers.

Methods

Here, we conducted a systematic review of the published literature on candidate biomarkers for PsA diagnosis and prognosis in MEDLINE(Pubmed), EMBase and the Cochrane library with the goal to identify clinically applicable PsA biomarkers. Meta-analyses were performed when a diagnostic bone and cartilage turnover biomarker was reported in 2 or moredifferent cohorts of PsA and control.

Results

We identified 1444 publications and 124 studies met eligibility criteria. We highlighted bone and cartilage turnover biomarkers, genetic markers, and autoantibodies used for diagnostic purposes of PsA, as well as acute phase reactant markers and bone and cartilage turnover biomarkers for activity or prognostic severity purposes. Serum cartilage oligometrix metalloproteinase levels were significantly increased in the PsA sera compared to Healthy Control (HC) with a standardized mean difference (SMD) of 2.305 (95%CI 0.795-3.816, p=0.003) and compared to osteoarthritis (OA) with a SMD of 0.783 (95%CI 0.015-1.551, p=0.046). The pooled serum MMP-3 levels were significantly higher in PsA patients than in PsO patients with a SMD of 0.419 (95%CI 0.119-0.719; p=0.006), but no significant difference was highlighted when PsA were compared to HC. While we did not identify any new genetic biomarkers that would be useful in the diagnosis of PsA, recent data with autoantibodies appear to be promising in diagnosis, but no replication studies have been published.

Conclusion

In summary, no specific diagnostic biomarkers for PsA were identified and further studies are needed to assess the performance of potential biomarkers that can distinguish PsA from OA and other chronic inflammatory diseases.

HLA-Cw1 and Psoriasis

Psoriasis is a chronic inflammatory skin condition with regional and ethnic differences in its prevalence and clinical manifestations. Human leukocyte antigen (HLA)-Cw6 is the disease allele conferring the greatest risk to psoriasis, but its prevalence is lower in Asian individuals. Recent studies have found associations between HLA-Cw1 and some Asian populations with psoriasis, especially Southern Chinese. HLA-Cw6 was associated with type I early-onset psoriasis, guttate psoriasis, Koebner phenomenon, and better response to methotrexate, interleukin (IL)-12/23, IL-17, and IL-23 targeting drugs. In contrast, HLA-Cw1 positivity has been associated with erythrodermic psoriasis, pustular psoriasis, and the axial type of psoriatic arthritis. Furthermore, HLA-Cw1 was more frequently associated with high-need patients who did not respond to conventional therapies. No known trigger factor nor autoantigen has been identified for HLA-Cw1 positivity. However, HLA-Cw1 has been linked to some viral agents. For example, cytotoxic T lymphocytes recognize multiple cytomegalovirus pp65-derived epitopes presented by HLA alleles, including HLA-C*01:02. In addition, cytomegalovirus can lead to severe exacerbation of psoriatic skin disease. The proposed interaction between viral infection, HLA-Cw1, and psoriasis is through the killer cell immunoglobulin-like receptors of natural killer cells. Given the diverse nature of psoriasis pathogenesis and the difference in HLA-Cw prevalence in different racial groups, more studies are needed to confirm the role of HLA-Cw1 in psoriasis.