Psoriatic Arthritis

Psoriatic arthritis (PsA) represents an inflammatory arthropathy associated with psoriasis. PsA has long been considered a disease with a low inflammatory profile, but growing evidence has recently recognized its multisystemic nature and association with extra-articular involvement in the form of colitis, uveitis, metabolic syndrome, and atherosclerosis.In subjects susceptible, through a complex interaction of a predisposing genetic background, an altered immune response mainly mediated by proinflammatory cytokines induces the inflammatory state.Articular inflammatory processes can involve axial skeleton (spondylitis), peripheral joints (peripheral arthritis), insertion sites of tendons and ligaments into bone (enthesitis), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, and soft tissue of digits (dactylitis). Any of these manifestations can occur singularly or in any of the possible combinations.Main radiological findings can be represented by articular erosions, exuberant new bone formations, osteolysis, periostitis, enthesitis, nonmarginal syndesmophytes, and ankylosis. In early and active phases of the disease, inflammatory aspects can be detected by use of magnetic resonance imaging (MRI) and ultrasonography.Diagnosis in early phases and immediate and effective therapy may be able to reduce disease severity, improving cutaneous, articular, patients' function and quality of life (QOL), and psychosocial outcomes.Inhibition of the structural radiological damage, clinical remission, and improvement of the patients' QOL represent the main aim of the treatment.The current treatment for nonsevere articular form consists initially of nonsteroidal antiinflammatory drugs (NSAIDs). Conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) represent therapeutic options in refractory cases, but biologic agents (bDMARDs), represented by tumor necrosis factor alpha (TNF-α), IL-12/23R, and IL-17 inhibitors, are then recommended in resistant patients.Among the emerging targeted synthetic DMARDs (tsDMARDs), apremilast (APR), a molecule that inhibits the activity of phosphodiesterase 4 (PDE4), has shown antiinflammatory effects. Furthermore, tofacitinib, a Janus kinase (JAK) inhibitor, has been recently found effective in PsA patients who had previously had an inadequate response to csDMARDs.The clinical heterogeneity of the disease and the multifaceted pathogenetic aspects involving multiple cytokines, cell lines, and molecules need to be further investigated with a collaborative and translational effort to improve outcomes of patients affected by PsA.