[Trigger factors for psoriasis]

Guselkumab, a Novel Monoclonal Antibody Inhibitor of the p19 Subunit of IL-23, for Psoriatic Arthritis and Plaque Psoriasis: A Review of Its Mechanism, Use, and Clinical Effectiveness

Psoriatic arthritis and plaque psoriasis are autoimmune conditions affecting multiple organs, including the skin. The pathophysiology and etiology of these conditions are not fully understood; however, numerous factors are believed to play a critical role, including genetics and environmental risk factors. Furthermore, research suggests the IL-23/IL-17 pathway partially mediates these diseases. Once the IL-23 receptor is bound and activated, two subunits, p19, and p40, act through different signaling pathways. Ultimately, inflammation is produced through the effector molecule, IL-17, other cytokines, and tumor necrosis factor (TNF). Traditionally, these chronic conditions have been treated with TNF-α inhibitors and methotrexate, a dihydrofolate reductase inhibitor. Although successful in inhibiting the immune system, these drugs can have many adverse effects due to their broad targets. In recent years, more targeted therapy has become popular. Guselkumab is a monoclonal antibody that inhibits the p19 subunit of IL-23. It has been FDA-approved to treat both plaque psoriasis and psoriatic arthritis. Clinical trials showing guselkumab's efficacy have been promising, even showing improvement in symptoms of plaque psoriasis patients resistant to adalimumab, a TNF-α inhibitor. Guselkumab has also been shown to be well tolerated with a similar safety profile as other biologics inhibiting the immune system. In addition to its efficacy in treating plaque psoriasis and psoriatic arthritis, the mechanism of action offers a targeted approach that may minimize the broad immunosuppressive effects often associated with traditional therapies, providing a potential advantage in the long-term management of these autoimmune conditions.

Xenobiotic Receptor CAR Is Highly Induced in Psoriasis and Promotes Keratinocyte Proliferation

Psoriasis is a chronic inflammatory skin disease with abnormal epidermal proliferation. Xenobiotics contribute to the pathogenesis of psoriasis. The mechanism linking xenobiotic stimuli with epidermal proliferation remains largely unknown. In this study, we investigated the role of CAR, a nuclear receptor (NR1I3) responsible for xenobiotics detoxification. We showed that CAR and its target genes were induced in the lesions from patients with psoriasis and imiquimod-treated mice. Proinflammatory cytokines (IL-17A, IL-22, oncostatin M, IL-1α, and TNF-α) synergistically increased the expressions of CAR and its target genes in both human and mouse keratinocytes. Overexpression of CAR promoted the G1/S transition by regulating cyclin E and c-Myc expressions, whereas the silencing of CAR attenuated it. Importantly, a selective CAR agonist 6-(4-chlorophenyl)imidazo(2,1-b)(1,3)thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime or the proinflammatory cytokines induced cyclin E and c-Myc, which were largely blocked by clotrimazole, a selective CAR antagonist, or CAR small interfering RNA. In addition, we showed that topical application of 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene, a selective agonist for mouse CAR, exacerbated the IMQ-induced psoriasis lesions with increased expressions of proliferative and inflammatory markers. In contrast, Car-knockout mice developed significantly milder lesions. In conclusion, these results showed that CAR plays a pathogenic role and, potentially, may be a target for the treatment of psoriasis.

The role of hormones in the pathogenesis of psoriasis vulgaris

Psoriasis vulgaris is a chronic, common skin disease, which affects the patient’s quality of life to the highest degree. Several exogenous factors and endogenous hormonal changes may act as triggers for psoriasis.

The skin possesses a true endocrine system, which is very important in multiple systemic diseases. A number of conditions are associated with psoriasis, and its severity can also be influenced by hormones. Even though the sex hormones and prolactin have a major role in psoriasis pathogenicity, there are a lot of other hormones which can influence the psoriasis clinical manifestations: glucocorticoids, epinephrine, thyroid hormones, and insulin.

Psoríase na infância e na adolescência

A psoríase é doença inflamatória crônica, imunologicamente mediada, recorrente e de caráter universal. Aproximadamente um terço dos adultos acometidos refere início da doença antes dos 16 anos de idade. Quanto mais precoce, mais grave tende a ser a evolução do quadro. Em crianças, as lesões podem ser fisicamente desfigurantes, causando prejuízos psicológicos e evidente comprometimento da qualidade de vida. As medicações sistêmicas utilizadas na psoríase, bem como a fototerapia, têm indicação limitada na infância, devido aos efeitos cumulativos das drogas, à baixa aceitação e ao risco de teratogenicidade. Nesta seção, discutiremos as principais manifestações clínicas da psoríase na infância e na adolescência, bem como os diagnósticos diferenciais, opções terapêuticas e prognóstico.

Understanding the pathogenesis of psoriasis, psoriatic arthritis, and autoimmunity via a fusion of molecular genetics and immunology

The goal of my laboratory is to understand the molecular genetics basis of the inflammatory skin disease psoriasis and associated psoriatic arthritis. In performing these studies my colleagues and I have begun to identify common pathways leading to autoimmunity as well, because some of the defective pathways leading to autoimmunity are the same in different autoimmune diseases. Some of these pathways are involved in determining the activation status of inflammatory cells in the resting state. Other pathways are likely to determine target organ specificity and will be unique to a particular disease. Our approaches rely on genetic studies with cases and families to identify the causative variants, and then functional studies to identify the role of these variants in the predisposition to psoriasis and autoimmunity. The advantage of genetics approaches to understanding diseases such as those of the immune system is that one can identify novel genes and pathways that were not previously suspected as being involved in either the immune system or tolerance.

Psoriatic erythroderma associated with enalapril

A 59-year-old man with a 35-year personal and positive family history of psoriasis was admitted to our department for treatment of psoriatic erythroderma. The patient had commenced therapy with enalapril 10 mg b.i.d. for the treatment of hypertension approximately 6 weeks before hospitalization. Five weeks after the initiation of enalapril, his psoriasis began to flare, and for a period of about 1 week it reached the extent of erythroderma. The patient did not associate the psoriatic flare with other factors such as infections, trauma, or stress. The patient presented with diffuse erythema and pronounced desquamation covering his entire trunk, scalp, and extremities (Figure). Nearly 100% of the body surface area was involved. The palms and soles were also affected, displaying erythema, hyperkeratosis, and painful fissures. The nails showed pits, oil spots, and subungual hyperkeratosis. The patient also had psoriatic arthritis affecting the interphalangeal joints of his fingers. Laboratory tests revealed an elevated erythrocyte sedimentation rate, an elevated creatinine level of 180 mmol/L, a blood urea nitrogen level of 10.8 mmol/L, and a uric acid level of 716 mmol/L. Urinalysis showed proteinuria of 1.5 g/24 h. The patient's renal condition was diagnosed as chronic tubulointerstitial nephritis, most probably related to his dermatologic disease. Allopurinol and dietary measures were recommended. Following treatment with methotrexate and replacement of enalapril therapy, the erythema and scaling gradually subsided and became confined to his pre-eruptive chronic plaques (approximately 5% of body surface area). Rechallenge with enalapril was not performed.

The genetics of psoriasis and autoimmunity

Psoriasis is an inflammatory/autoimmune disease and, as with many autoimmune diseases, is associated with alleles from the major histocompatibility complex (MHC). With psoriasis and autoimmune disease, the penetrance of the MHC-associated alleles is never 100%, even for monozygotic twins. This may be because development requires additional environmental and/or genetic modifiers or requires specific T-cell receptor arrangements. Families segregating single or multilocus susceptibility alleles other than the MHC have also been reported. Overlapping genetic locations of loci for different autoimmune diseases have been known for several years and are starting to reveal common genes or genetic variants. These include genes normally involved in preventing spontaneous T-cell activation or proliferation, immune synapse formation, or cytokine production via pathways such as those mediated by NFkappaB and those involved in thymic selection. Autoimmunity may also involve dysregulation of genes or pathways regulated by the RUNX family of transcription factors. RUNX is involved in hematopoietic cell development, development of T cells in the thymus, chromatin remodeling, and gene silencing. Hence, its effect on cells of the immune system may be due to variable changes in gene expression and could account for variable body surface involvement and waxing and waning of disease.