Description

PsA is a complex inflammatory disease with heterogeneous clinical features, which complicates psoriasis in 30% of patients .

The exact aetiopathogenesis of psoriasis is not completely explained. Pathological mechanism involves skin inflammation and hyperproliferation of keratinocytes induced innate and adaptive immune cells. Genetic, immunological and environmental factors are considered the most important aetiologies.

Psoriasis is a chronic relapsing disease, which often necessitates a long-term therapy. Mild to moderate psoriasis can be treated topically with a combination of glucocorticoids, vitamin D analogues, and phototherapy. Moderate to severe psoriasis often requires systemic treatment. The presence of comorbidities such as psoriasis arthritis is also highly relevant in treatment selection.

Methotrexate (MTX) has remained the backbone of the treatment for moderate to severe psoriasis ever since its first use nearly half a century ago.

Over the years, its high efficacy, low cost, relative ease of administration and usefulness in concomitant psoriatic arthritis have contributed in making MTX the drug of choice in managing severe psoriasis. Although the majority of patients achieve remission of disease activity with MTX, a significant proportion may experience mild and transient adverse effects. From time to time, various guidelines on the use of MTX have correctly and adequately stressed the need for strict monitoring of haematological and hepatic adverse events.

The transcription factor known as nuclear factor of kappa light chain enhancer of activated B cells (NF-κB) controls a large number of genes in immune cells in response to inflammation, infection, and other stimuli. Proinflammatory cytokines, chemokines, and growth factors are among the many genes whose transcription is boosted when the NF-κB pathway is activated. These genes are all implicated in the initiation and maintenance of the inflammatory response in psoriatic illness .

The intracellular scaffold protein known as caspase recruitment domain family member 14 (CARD14) rs34367357 is highly abundant in keratinocytes and mediates NF-κB activation by forming a CBM (CARD14-BCL10-MALT1) signaling complex .

Gain-of-function mutations in CARD14 have been demonstrated to increase the development of the CBM complex in keratinocytes, which causes the NF-κB pathway to become hyperactivated. Neutrophils, dendritic cells, and T cells are then drawn in and activated as a result of the transcription of several chemokines (CCL20, CXCL1, and CXCL2), cytokines (IL-36 and IL-19), and antimicrobial peptides. Two key cytokines in the pathophysiology of psoriasis, IL-17 and IL-22, are downstreamly expressed when activated dendritic cells release IL-23 .