Psoriasis is a chronic, systemic immune-mediated disease characterized by development of erythematous, indurated, scaly, pruritic plaques on the skin. Psoriasis is frequently associated to comorbidities, including psoriatic arthritis, cardiovascular diseases, diabetes mellitus, obesity, non-alcoholic fatty liver disease, and inflammatory bowel diseases. In this review, we discuss the pathophysiological relationship between psoriasis and cardio-metabolic comorbidities and the importance of therapeutic strategies to reduce systemic inflammation in patients with moderate-to-severe psoriasis. Pathogenesis of psoriasis and its comorbidities share both genetic predisposition and inflammatory pathways, which include the TNFα and the IL-23/IL-17 pathways. These pathways are selectively addressed by biological treatments, which have substantially changed the outcomes of psoriasis therapy and affect positively comorbidities including reducing cardiovascular risk, allowing a more comprehensive approach to the patient.

Objective To estimate the incidence of psoriatic arthritis (PsA) in patients with psoriasis who had received a continuous treatment with biological disease-modifying antirheumatic drugs (bDMARDs) compared with phototherapy. Methods A retrospective non-randomised study involving patients with moderate-to-severe plaque psoriasis, who were prescribed at least 5 years of bDMARDs or at least three narrow-band ultraviolet light B (nb-UVB) phototherapy courses, and did not have a diagnosis of PsA at enrolment. Development of PsA in each patient was assessed by a rheumatologist according to the Classification for Psoriatic Arthritis criteria. The annual and cumulative incidence rate of PsA was estimated by using an event per person-years analysis. Cox proportional hazards models were undertaken to assess the hazard risk (HR) of PsA after adjustment for confounders. Results A total of 464 psoriatic patients (bDMARDs, n=234 and nb-UVB, n=230) were followed between January 2012 and September 2020 (corresponding to 1584 and 1478 person year of follow-up for the two groups, respectively). The annual incidence rate of PsA was 1.20 cases (95% CI 0.77 to 1.89) versus 2.17 cases (95% CI 1.53 to 3.06) per 100 patients/year in the bDMARDs versus phototherapy group, respectively (HR 0.29, 0.12–0.70; p=0.006). The variables independently associated with higher risk of PsA were older age (adjusted HR 1.04, 1.02–1.07), nail psoriasis (adjusted HR 3.15, 1.63–6.06) and psoriasis duration >10 years (adjusted HR 2.02, 1.09–3.76); notably, bDMARDs treatment was associated with a lower risk of incident PsA (adjusted HR 0.27, 0.11–0.66). Conclusions bDMARDs treatment may delay or reduce the risk of incident PsA in patients with moderate-to-severe chronic plaque psoriasis.

Environmental air pollution is defined by the World Health Organization (WHO) as the contamination of the ambient air by any chemical, physical, or biological agent that modifies the natural characteristic of the atmosphere.¹ The main pollutant compounds include coarse particulate matter (PM; 2.5-10.0 μm in diameter, PM10) and fine PM (<2.5 μm in diameter, PM2.5); gaseous products, ie, carbon monoxide (CO) and oxides of nitrogen (NO_x); and volatile organic products such as benzene (C₆H₆). These compounds are produced mostly by fossil fuel combustion from vehicle and industry emissions. Additional secondary pollutions are derived from the interaction of volatile organic compounds and NO_x upon UV radiation photoactivation.² Air pollution exerts negative effects on human health, and has been associated with stroke, heart disease, chronic obstructive pulmonary disease, osteoporosis, and infertility.^3-6 After inhalation, pollutants can circulate in the blood stream, exerting oxidative damage and causing inflammation. Moreover, air pollutants can directly come into contact with the skin.⁷ Exposure to diesel exhaust particles could activate skin resident T-cells, resulting in abnormal production of pro-inflammatory cytokines including tumor necrosis factor α (TNF-α) and interleukins (ILs), including IL-1α, IL-1β, IL-6, and IL-8.⁸ Indeed, worsening of different inflammatory cutaneous diseases including atopic dermatitis, photoaging, and acne have been associated with exposure to air pollution.^9-13 Psoriasis is a chronic inflammatory disease with a relapsing-remitting course and selected environmental factors such as infections and/or drugs may trigger disease flares.¹⁴ Whether air pollution could trigger psoriasis flares is not known.¹⁵ The objective of this study was to investigate whether short-term exposure to environmental air pollution is associated with psoriasis flares.

Epidemiological data demonstrate strong associations between psoriasis and metabolic comorbidities, including obesity, hypertension, diabetes mellitus, dyslipidemia, and non-alcoholic fatty liver disease. The presence of metabolic comorbidities significantly influences the selection and effectiveness of pharmacological treatments. Some drugs should be prescribed with caution in patients with metabolic comorbidities because of an increased risk of adverse events, while others could have a reduced effectiveness. The aim of this narrative review is to highlight the challenges that healthcare professionals may face regarding the management of psoriasis in patients with metabolic comorbidities. In the first part of the article, the epidemiological association between psoriasis and metabolic comorbidities and their pathogenetic mechanisms is summarized. The second part describes the efficacy and safety profile of conventional and biologic drugs in patients with selected metabolic comorbidities including obesity, non-alcoholic fatty liver disease/hepatic steatosis, and diabetes. Finally, the role of pharmacological and non-pharmacological interventions, such as diet, alcohol abstinence, physical activity, and smoking avoidance is discussed. In conclusion, the choice of the best approach to manage patients with psoriasis with metabolic comorbidities should encompass both tailored pharmacological and individualized non-pharmacological interventions.

Background: Psoriasis is an inflammatory skin disease presenting with erythematous and desquamative plaques with sharply demarcated margins, usually localized on extensor surface areas. Objective: To describe the common differential diagnosis of plaque psoriasis classified according to its topography in the scalp, trunk, extremities, folds (i.e., inverse), genital, palmoplantar, nail, and erythrodermic psoriasis. Methods: A narrative review based on an electronic database was performed including reviews and original articles published until 1 September 2020, assessing the clinical presentations and differential diagnosis for psoriasis. Results: Several differential diagnoses could be considered with other inflammatory, infectious, and/or neoplastic disorders. Topographical differential diagnosis may include seborrheic dermatitis, tinea capitis, lichen planopilaris in the scalp; lupus erythematosus, dermatomyositis, cutaneous T-cell lymphomas, atopic dermatitis, syphilis, tinea corporis, pityriasis rubra pilaris in the trunk and arms; infectious intertrigo in the inguinal and intergluteal folds and eczema and palmoplantar keratoderma in the palms and soles. Conclusions: Diagnosis of psoriasis is usually straightforward but may at times be difficult and challenging. Skin cultures for dermatophytes and/or skin biopsy for histological examination could be required for diagnostic confirmation of plaque psoriasis.