Role of the IL-23 pathway in the pathogenesis and treatment of enthesitis in psoriatic arthritis

Management of psoriatic arthritis: a consensus opinion by expert rheumatologists

Background

Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease involving several articular and extra-articular structures. Despite the important progresses recently made in all of the aspects of this disease, its management is still burdened by unresolved issues. The aim of this exercise was to provide a set of statements that may be helpful for the management of PsA.

Methods

A group of 38 Italian rheumatologists with recognized expertise in PsA selected and addressed the following four topics: "early PsA," "axial-PsA," "extra-articular manifestations and comorbidities," "therapeutic goals." Relevant articles from the literature (2016-2022) were selected by the experts based on a PubMed search. A number of statements for each topic were elaborated.

Results

Ninety-four articles were selected and evaluated, 68 out of the 1,114 yielded by the literature search and 26 added by the Authors. Each of the four topic was subdivided in themes as follows: transition from psoriasis to PsA, imaging vs. CASPAR criteria in early diagnosis, early treatment for "early PsA"; axial-PsA vs. axialspondyloarthritis, diagnosis, clinical evaluation, treatment, standard radiography vs. magnetic resonance imaging for "axial PsA"; influence of inflammatory bowel disease on the therapeutic choice, cardiovascular comorbidity, bone damage, risk of infection for "comorbidities and extra-articular manifestations"; target and tools, treat-to-target strategy, role of imaging for "therapeutic goals." The final document consisted of 49 statements.

Discussion

The final product of this exercise is a set of statements concerning the main issues of PsA management offering an expert opinion for some unmet needs of this complex disease.

Osteoimmunology of Spondyloarthritis

The mechanisms underlying the development of bone damage in the context of spondyloarthritis (SpA) are not completely understood. To date, a considerable amount of evidence indicates that several developmental pathways are crucially involved in osteoimmunology. The present review explores the biological mechanisms underlying the relationship between inflammatory dysregulation, structural progression, and osteoporosis in this diverse family of conditions. We summarize the current knowledge of bone biology and balance and the foundations of bone regulation, including bone morphogenetic protein, the Wnt pathway, and Hedgehog signaling, as well as the role of cytokines in the development of bone damage in SpA. Other areas surveyed include the pathobiology of bone damage and systemic bone loss (osteoporosis) in SpA and the effects of pharmacological treatment on focal bone damage. Lastly, we present data relative to a survey of bone metabolic assessment in SpA from Italian bone specialist rheumatology centers. The results confirm that most of the attention to bone health is given to postmenopausal subjects and that the aspect of metabolic bone health may still be underrepresented. In our opinion, it may be the time for a call to action to increase the interest in and focus on the diagnosis and management of SpA.

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.

Cellular nanovesicles with bioorthogonal targeting enhance photodynamic/photothermal therapy in psoriasis

The interaction between over-proliferating keratinocytes and excessive activated immune cells contributes to the development and progression of psoriasis. Photodynamic therapy (PDT)/photothermal therapy (PTT) is a promising method to treat skin diseases due to their synergistic effect and low side effect. Cell membrane is an ideal cell-mediated drug delivery platform with inherent biocompatibility, but lacks of specific targeting properties to increase drug accumulation in the psoriatic site. Here, we develop a new PDT/PTT strategy to treat psoriasis, based on cell membrane functionalization by metabolic glycoengineering with unnatural sugars, which label cell membranes with chemical tags for subsequent targeting. In our study, in order to enhance the PDT/PTT effect, N₃-labeled cell membrane-derived nanovesicles coated with IR-780 nanoparticals (N₃-NV-INPs) are constructed, which can specifically recognize DBCO-modified psoriatic lesions through bioorthogonal click chemistry to achieve targeted PDT/PTT effect. The results showed that N₃-NV-INPs could specifically target the psoriatic lesions, enhance the synergistic effect of PDT/PTT under the irradiation of near-infrared light, exhaust excessive proliferation of keratinocytes, regulate immunity, reduce the release of cytokines, such as IL-17, IL-22, TNF-α, improve epidermal hyperplasia, and effectively relieve the symptoms of psoriasis. Taken together, we constructed cellular nanovesicles based on an alternative artificial targeting strategy to enhance PDT/PTT effect in psoriasis, which shows great potential in clinical application. STATEMENT OF SIGNIFICANCE: The major challenge in the treatment of psoriasis is how to effectively deliver drugs to the lesions to exhaust overproliferating keratinocytes and modulate immunity. A newly-developed cell membrane-coating technology combined with biorthogonal targeted delivery promotes more drug accumulation at the lesions of the disease. Incorporation of an effective photosensitizer into the lesions of psoriasis site results in exert PDT/PTT effect under the irradiation of near-infrared light. The synergistic PDT/PTT effect can effectively exhaust keratinocytes and immune cells in the epidermis and dermis, reduce the release of inflammatory cytokines, and relieve the symptoms of psoriasis. This unique functional cell membrane nanovesicles combined with bioorthogonal targeting is applied to enhance the PDT/PTT effect in psoriasis and may provide a solution for the clinical treatment of other inflammatory skin diseases.

Experimental and Investigational Pharmacotherapy for Psoriatic Arthritis: Drugs of the Future

In recent years, different studies have shown in psoriatic arthritis (PsA), the pathogenetic role of multiple cytokines other than tumor necrosis factor-α, such as interleukin-17 (IL-17), and IL-23 and dysfunction of Janus kinase (JAK)-signal family pathway. These molecules also represent the target of recently developed biologic (bDMARDs) and targeted synthetic disease modifying antirheumatic drugs (DMARDs) (tsDMARDs) currently investigated in several Phase II and III randomized controlled trials (RCTs). This review examines the therapeutic efficacy and safety of most recent developed IL-17, IL-23 and JAK inhibitors and highlights how these new PsA therapies are going to revolutionize the management of PsA in the next few years. Ongoing RCTs of these molecules in PsA are also described. Available literature on new anti-IL-17 and anti-IL-23 agents and JAK inhibitors demonstrates the potential role of these molecules as effective therapeutic strategies across multiple PsA clinical domains, along with an acceptable tolerability and safety profile, thus expanding the treatment options available for PsA patients. Of note, other molecules are under investigation, and among those, potential therapeutic strategies seem to be represented by single antibodies blocking simultaneously two cytokines, the agents inhibiting mammalian target of rapamycin (mTOR), receptor retinoic acid receptor-related orphan receptor gamma (RORγt), A3 adenosine receptor (A3 AR), and K⁺ channel voltage channel inhibitors. Remarkable progress has been made in PsA pharmacotherapy, and novel bDMARDs targeting IL17A and tsDMARDs (JAK-inhibitors) represent promising therapies. More clinical trials are needed to better characterize the efficacy and safety profile of these therapeutic agents in PsA treatment.