Advances and Controversies in Our Understanding of Guttate and Plaque Psoriasis

Acute guttate psoriasis (AGP) is considered an uncommon variant of psoriasis (PsO), characterized as a widespread eruption of erythematous, psoriasiform papules, and plaques on the trunk, extremities, and scalp. Predisposing factors include a family history of PsO, variation in the main PsO susceptibility gene HLA-Cw*0602, and previous infection with viruses or acute β-hemolytic Streptococcus A program focused on controversies and recent advances in understanding AGP was presented at the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2022 annual meeting. Topics included an overview of clinical presentation and natural history, predisposing genetic and environmental factors, and the recent molecular profiling that supports classification of AGP as a form of PsO. Early molecular profiling studies using proteomic signatures have suggested similarities between AGP and contact dermatitis, but recent studies using gene expression profiling and gene set enrichment scores demonstrate that AGP is more similar to chronic PsO. The expression of regulatory immune pathways seen with AGP suggests potential for early and sustained remission if the disease is suppressed by targeted treatments. Published case reports documenting clinical improvement of AGP with biologics that antagonize interleukin (IL)-12/23, IL-23, and IL-17 support the role of the IL-23/IL-17 axis in AGP, similar to that in PsO. Data supporting the use of antibiotics and other therapeutic agents for AGP are lacking, and randomized controlled trials are needed. Trial design for AGP is challenged by the low incidence, tendency for spontaneous remission, lack of validated end points, and the need for long-term follow up.

Pathogenesis of psoriasis in the "omic" era. Part II. Genetic, genomic and epigenetic changes in psoriasis

Psoriasis is a multifactorial disease in which genetic, environmental and epigenetic factors regulating gene expression play a key role. In the “genomic era”, genome-wide association studies together with target genotyping platforms performed in different ethnic populations have found more than 50 genetic susceptible markers associated with the risk of psoriasis which have been identified so far. Up till now, the strongest association with the risk of the disease has been proved for HLA-C*06 gene. The majority of other psoriasis risk SNPs are situated near the genes encoding molecules involved in adaptive and innate immunity, and skin barrier function. Many contemporary studies indicate that the epigenetic changes: histone modification, promoter methylations, long non-coding and micro-RNA hyperexpression are considered as factors contributing to psoriasis pathogenesis as they regulate abnormal keratinocyte differentiation and proliferation, aberrant keratinocytes – inflammatory cells communication, neoangiogenesis and chronic inflammation. The circulating miRNAs detected in the blood may become specific markers in the diagnosis, prognosis and response to the treatment of the disease. The inhibition of expression in selected miRNAs may be a new promising therapy option for patients with psoriasis.

The contribution of IL-17 to the development of autoimmunity in psoriasis

Psoriasis is an (auto)immune-mediated disease that manifests as widespread desquamative erythema. The TNF-α/IL-23/IL-17A axis is crucial to its pathogenesis, which is demonstrated by its excellent therapeutic response to biologics that target this axis. There is a strong association between HLA-C*0602 and psoriasis, and researchers have identified autoantigens that are restricted to this major histocompatibility class I molecule. These auto-Ags include LL-37, A disintegrin and metalloprotease domain containing thrombospondin type 1 motif-like 5 (ADAMTSL5), and keratin 17. IL-17A-producing T cells have been identified in T cell populations that are reactive to these auto-Ags. In addition, lipid Ags have surfaced as candidate auto-Ags that activate IL-17A-producing T cells in a CD1a-restricted manner. In this article, we review the candidate auto-Ags that may contribute to the activation of the IL-17A-deviated immune response in psoriasis.

ERAP1 and HLA-C*06 are strongly associated with the risk of psoriasis in the population of northern Poland

INTRODUCTION

HLA-C*06 is a major psoriasis genetic risk marker. Recent reports have been focused on the role of different polymorphisms within genes involved in the functioning of the epidermal barrier and antigen processing in the pathogenesis of psoriasis. Data on the association between genetic variants of LCE3B_LCE3C, CSTA, ERAP1, ZAP70 and this dermatosis in the population from Eastern Europe are lacking.

AIM

To compare the association between known genetic risk markers and psoriasis in a cohort of northern Polish patients with psoriasis and healthy controls.

MATERIAL AND METHODS

Based on previous studies' results, five susceptibility loci: HLA-C, LCE3C_LCE3B, ERAP1, ZAP70 and CSTA were selected for genotyping in 148 patients with chronic plaque psoriasis and 146 healthy controls. Each patient with this disease was clinically assessed with the Psoriasis Area and Severity Index.

RESULTS

The study population showed a significant association of psoriasis and a single nucleotide polymorphism in the ERAP1 - rs26653 (p = 3.11 × 10-5) and HLA-C*06 allele (p = 1.02 × 10-11) when compared with the control group. The presence of HLA-C*06 or rs26653 G allele significantly increased the risk of psoriasis by 2.4 times or twice, respectively. Carrying rs26653 C allele considerably decreased the risk of psoriasis by 1.5 times.

CONCLUSIONS

In the context of pathogenesis of psoriasis, our findings might give the evidence on disturbances in the proteolytic processing of N-terminal fragments of antigens presented via major histocompatibility complex class I to T cells.

Evaluation of Psoriasis Genetic Risk Based on Five Susceptibility Markers in a Population from Northern Poland

Psoriasis genetic background depends on polygenic and multifactorial mode of inheritance. As in other complex disorders, the estimation of the disease risk based on individual genetic variants is impossible. For this reason, recent investigations have been focused on combinations of known psoriasis susceptibility markers in order to improve the disease risk evaluation. Our aim was to compare psoriasis genetic risk score (GRS) for five susceptibility loci involved in the immunological response (HLA-C, ERAP1, ZAP70) and in the skin barrier function (LCE3, CSTA) between patients with chronic plaque psoriasis (n = 148) and the control group (n = 146). A significantly higher number of predisposing alleles was observed in patients with psoriasis in comparison to healthy individuals (6.1 vs. 5.2, respectively; P = 8.8×10⁻⁷). The statistical significance was even more profound when GRS weighted by logarithm odds ratios was evaluated (P = 9.9×10⁻¹⁴). Our results demonstrate the developed panel of five susceptibility loci to be more efficient in predicting psoriasis risk in the Polish population and to possess higher sensitivity and specificity for the disease than any of the markers analyzed separately, including the most informative HLA-C*06 allele.

The HLA-C*06 allele as a possible genetic predisposing factor to psoriasis in South Indian Tamils

Psoriasis is a multi-factorial heritable prototypical immune-mediated inflammatory disease, characterized by hyperproliferation of keratinocytes in the affected skin. There are no studies till date, to the best of our knowledge, about the association of HLA-C*06, the risk variant in the PSORS 1 susceptibility locus that confers the greatest risk for early onset of psoriasis, with the disease in South Indian Tamil patients with psoriasis. The present study was performed to determine the association of HLA-C*06 with psoriasis in the South Indian Tamil ethnic population. Three hundred and fifty-five cases of psoriasis and 360 healthy controls were included in this case-control study. Severity grading according to psoriasis area severity index (PASI) scoring was done in patients with psoriasis. PCR assays with sequence-specific primers (PCR-SSP) were used for specific detection of HLA-C*06. PCR with analysis of restriction fragment length polymorphism was used to distinguish between patients homozygous and heterozygous for HLA-C*06. We observed that those with the HLA-C*06-positive allele had a 3.5 times higher odds of having psoriasis compared to those without, [p < 0.0001, OR 3.5, 95 % CI (2.59-4.79)]. Among cases of psoriasis, it was noted that there was a significant association of HLA-C*06 positivity with female psoriatics [p = 0.006; OR 2.49 (1.28-4.87)] and early age of onset of psoriasis [p = 0.002; OR 2.04 (1.29-3.20)]. Our results suggest that the HLA-C*06 allele is positively associated with susceptibility to psoriasis, female gender and early onset of psoriasis in South Indian Tamils.

Four polymorphisms of VEGF (+405C>G, -460T>C, -2578C>A, and -1154G>A) in susceptibility to psoriasis: a meta-analysis

The contribution of genetic polymorphisms in the vascular endothelial growth factor (VEGF) gene to psoriasis risk is a controversial topic. The aim of this meta-analysis was to investigate large-scale evidence to determine the degree to which four common VEGF polymorphisms (+405C>G [dbSNP: rs2010963], -460T>C [dbSNP: rs833061], -2578C>A [dbSNP: rs699947], and -1154G>A [dbSNP: rs1570360]) are associated with susceptibility to psoriasis. A literature search of PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, and Chinese Biomedical Literature Database was conducted to identify all eligible studies published before September 15, 2013. The principal outcome measure for evaluating the strength of the association was crude odds ratios (ORs) along with their corresponding 95% confidence intervals (95% CIs). Two thousand five hundred thirty-one patients and 2670 controls from nine case-control studies detailing a possible association between the VEGF genotypes and psoriasis risk were selected. Our meta-analysis provides evidence that two independent alleles +405G and -460C may be a protective factor for psoriasis in Asians, whereas the -1154A allele had a slight but statistically significant preventive effect on the development of psoriasis in Caucasians. The -2578C>A polymorphism, however, did not correlate with any significant difference between patients and healthy controls, even when the groups were stratified by ethnicity. Results from the meta-analysis do support the hypothesis that single-nucleotide polymorphism markers at +405C>G, -460C>T, and -1154G>A of the VEGF gene may serve as biological markers of psoriasis. Future studies should investigate interactions among multiple genotypes and environmental exposures to identify the role of proangiogenic markers in psoriasis and to delineate the underlying mechanisms of psoriasis.