Interactions between adiposity and genetic polymorphisms on the risk of psoriasis

Disentangling the complexity of psoriasis in the post-genome-wide association era

In recent years, genome-wide association studies (GWAS) have been instrumental in unraveling the genetic architecture of complex diseases, including psoriasis. The application of large-scale GWA studies in psoriasis has illustrated several associated loci that participate in the cutaneous inflammation, however explaining a fraction of the disease heritability. With the advent of high-throughput sequencing technologies and functional genomics approaches, the post-GWAS era aims to unravel the functional mechanisms underlying the inter-individual variability in psoriasis patients. In this review, we present the key advances of psoriasis GWAS in under-represented populations, rare, non-coding and structural variants and epistatic phenomena that orchestrate the interplay between different cell types. We further review the gene-gene and gene-environment interactions contributing to the disease predisposition and development of comorbidities through Mendelian randomization studies and pleiotropic effects of psoriasis-associated loci. We finally examine the holistic approaches conducted in psoriasis through system genetics and state-of-the-art transcriptomic analyses, discussing their potential implication in the expanding field of precision medicine and characterization of comorbidities.

Considerations of the Genetic Background of Obesity among Patients with Psoriasis

Psoriasis comorbidities may emerge from pleiotropic mechanisms, including common proinflammatory pathways, cellular mediators or genetic predisposition. Obesity is considered to be an independent risk factor of psoriasis, which may influence the severity of the disease and its early onset, decrease patients’ quality of life, alter response to psoriasis therapies and affect morbidity by reduced life expectancy due to cardiovascular events. Although novel approaches, including genetic techniques, have provided a wide range of new research, there are still scarce studies elaborating on the common genetic background of psoriasis and obesity. The aim of this study was to present and evaluate a possible common genetic background of psoriasis and concomitant increased body mass based on the review of the available literature.

Analysis of the Potential Genetic Links between Psoriasis and Cardiovascular Risk Factors

Cardiovascular risk factors are one of the most common comorbidities in psoriasis. A higher prevalence of hypertension, insulin resistance and type 2 diabetes, dyslipidemia, obesity, metabolic syndrome, depression, as well as cardiovascular disease was confirmed in psoriatic patients in comparison to the general population. Data suggest that psoriasis and systemic inflammatory disorders may originate from the pleiotropic interactions with many genetic pathways. In this review, the authors present the current state of knowledge on the potential genetic links between psoriasis and cardiovascular risk factors. The understanding of the processes linking psoriasis with cardiovascular risk factors can lead to improvement of psoriasis management in the future.

Critical role of environmental factors in the pathogenesis of psoriasis

Psoriasis is a common cutaneous disease with multifactorial etiology including genetic and non-genetic factors, such as drugs, smoking, drinking, diet, infection and mental stress. Now, the role of the interaction between environmental factors and genetics are considered to be a main factor in the pathogenesis of psoriasis. However, it is a challenge to explore the mechanisms how the environmental factors break the body balance to affect the onset and development of psoriasis. In this article, we review the pathogenesis of psoriasis and summarize numerous clinical data to reveal the association between environmental factors and psoriasis. In addition, we focus on the mechanisms of environmental risk factors impact on psoriasis and provide a series of potential treatments against environmental risk factors.

Epidemiological Assessments of Skin Outcomes in the Nurses' Health Studies

OBJECTIVES

To review the contribution of the Nurses' Health Studies (NHSs) to identifying epidemiological factors associated with multiple skin diseases, including skin cancer, psoriasis, and other inflammatory and autoimmune skin diseases.

METHODS

We carried out a narrative review of NHS articles published between 1976 and 2016.

RESULTS

The NHSs have identified environmental and lifestyle factors related to psoriasis, supporting obesity and smoking as psoriasis risk factors; associations between psoriasis and diabetes, myocardial infarction, and Crohn's disease, supporting psoriasis as a systemic disorder; and associations of pigmentary traits, ultraviolet radiation, and lifestyle factors such as citrus consumption with risk of skin cancer. Genetic studies have identified novel genetic loci for skin pigmentation (e.g., IRF4, SLC24A4, NID1, and EDNRB) and skin cancer (e.g., TET2 and HERC2-OCA2). Work continues on highly prevalent but less studied skin conditions such as rosacea, acne, and atopic dermatitis. The NHS results have influenced public health policies on indoor tanning devices.

CONCLUSIONS

The NHSs have provided invaluable resources on skin disease population science and contributed to the etiological understanding of multiple skin disorders.

Presence of selected metabolic syndrome components in patients with psoriasis vulgaris

Introduction

Recent studies have suggested a strong association between psoriasis and obesity, dyslipidemia, hypertension, resistance to insulin and metabolic syndrome.

Aim

To assess the prevalence of selected metabolic syndrome components in patients with psoriasis and the effect of the abnormalities on the disease activity.

Material and methods

Two hundred and forty-six patients diagnosed with psoriasis and 75 healthy individuals as controls were included in the study. Psoriasis activity was evaluated by the Psoriasis Area and Severity Index (PASI).

Results

There was a statistically significant difference in triglyceride concentration between psoriasis patients and controls (p = 0.00001), which was not found for high-density lipoprotein (HDL) concentration. Mean values of serum glucose level in patients with psoriasis were significantly higher than in controls (p = 0.046). Further statistical analysis of the obtained results showed significantly higher systolic blood pressure in the psoriasis patients than in the controls (p = 0.0001), but there was no statistically significant difference in diastolic blood pressure between the investigated groups (p > 0.05).

Conclusions

Higher prevalence of metabolic syndrome components was observed in patients with psoriasis than in the general population.

Investigation of association of the IL-12B and IL-23R genetic variations with psoriatic risk in a South Indian Tamil cohort

BACKGROUND

Psoriasis is a T-cell mediated chronic systemic inflammatory skin disease. Emerging evidences suggest the interleukin (IL)-12B and IL-23R genes encoding the common p40 subunit of IL-12 and IL-23 are the key cytokines in T-helper (Th)1 and Th17 differentiation and function. Certain allelic variants of these genes significantly influence the risk of psoriasis. Hence we undertook to study the association of IL-12B and IL-23R gene polymorphisms with disease susceptibility in South Indian Tamil patients with psoriasis.

METHODS

360 psoriatics and 360 healthy controls were included in this case control study. IL-12B gene (rs3212227) and IL-23R gene (rs2201841, rs10889677 and rs11805303) polymorphisms were typed by using TaqMan 5'allele discrimination assay and cytokine levels were assayed by ELISA.

RESULTS

We observed that the patients carrying the risk genotypes of IL-12B (rs3212227) and IL-23R (rs2201841) conferred an increased susceptibility to psoriasis. We did not find any significant association between IL-23R (rs10889677 and rs11805303) gene polymorphisms and psoriasis risk in South Indian Tamil population. We did not observe any significant difference in haplotypes between the psoriasis cases and controls. We observed a significant increase in the mean IL-23 levels in psoriatics and the higher levels of IL-23 were found in the minor variant genotype CC when compared with that of heterozygous CT and major variant TT genotypes of rs2201841. Individual genotypes of rs10889677 and rs11805303 and IL-12 (rs3212227) were not significantly associated with their plasma levels.

CONCLUSION

Our results suggest that IL-12B (rs3212227) and IL-23R (rs2201841) polymorphisms confer increased risk of psoriasis in our ethnic South Indian Tamils.

Body Mass Index, Genetic Susceptibility, and Risk of Complications Among Individuals with Crohn's Disease

BACKGROUND

Obesity is associated with systemic and intestine-specific inflammation and alterations in gut microbiota, which in turn impact mucosal immunity. Nonetheless, a specific role of obesity and its interaction with genetics in the progression of Crohn's disease (CD) is unclear.

METHODS

We conducted a cross-sectional study of patients with CD enrolled in Prospective Registry in Inflammatory Bowel Disease Study at Massachusetts General Hospital (PRISM). Information on diagnosis of CD and its complications were collected and confirmed through review of medical records. A genetic risk score was calculated using previously reported single-nucleotide polymorphisms-associated genome-wide with CD susceptibility. We used logistic regression to estimate the effect of body mass index (BMI) and its interaction with genetic risk on risk of CD complications.

RESULTS

Among 846 patients with CD, 350 required surgery, 242 with penetrating disease, 182 with stricturing disease, and 226 with perianal disease. There were no associations between obesity (BMI ≥ 30 kg/m2) and risk of perianal disease, stricturing disease, or surgery. Compared with normal-weight individuals with BMI < 25 kg/m2, obesity was associated with lower risk of penetrating disease (odds ratio [OR = 0.56; 95% confidence interval [CI], 0.31-0.99). This association persists among a subgroup of participants with available BMI before development of penetrating disease (OR = 0.40; 95% CI, 0.16-0.88). There were no interactions between BMI and genetic risk score on risk of CD complications (all P interaction > 0.28).

CONCLUSIONS

Our data suggest that obesity does not negatively impact long-term progression of CD, even after accounting for genetic predisposition.

[Psoriasis vulgaris in children and adolescents. Pathogenesis, clinical picture and therapy]

BACKGROUND

The prevalence of psoriasis vulgaris in childhood ranges from 0.12 % in infants to 1.2 % in adolescents. Psoriasis is a polygenic disease triggered by external factors and is influenced by comorbidities such as obesity, metabolic syndrome, chronic inflammatory bowel diseases and rheumatic diseases.

CLINICAL FEATURES

Its clinical presentation is variable. Typical complications include erythroderma, disseminated pustulosis and arthropathy.

THERAPY

Amongst a wide range of topical or systemic therapeutical options, individualized treatment is based on severity, site and extent of cutaneous involvement, age, potential side-effects and comorbidities.

Combined effects of the BDNF rs6265 (Val66Met) polymorphism and environment risk factors on psoriasis vulgaris

Smoking, alcohol consumption and higher body mass index (BMI) are well established risk factors for psoriasis and also associated with the clinical traits of the disease. And the genetic influences on these three risk factors indeed exist. Previously studies have demonstrated these risk factors related genetic variants may also play a role in the development of risk factors-related diseases. Then we performed a hospital-based study in order to evaluate the combined effect of the risk factors and their related polymorphism rs6265 in brain-derived neurotrophic factor (BDNF) gene on psoriasis vulgaris (PV) risk and clinic traits. The case-control study involved 660 subjects including 345 cases and 315 controls in Chinese Han population. The variant of rs6265 was typed by SNaPshot Multiplex Kit (Applied Biosystems Co., USA). We confirmed that higher BMI (≥25), smoking and alcohol consumption were risk factors for PV, and the estimated ORs were 1.63(95 % confidence interval (CI); 1.12-2.37), 2.09(95 % CI; 1.44-3.03) and 1.65(95 % CI; 1.15-2.37) respectively. Genotype and allele distributions did not differ significantly between case and control. However, we found combined effect of rs6265 genotype (GG) and higher BMI (≥25) increased risk of PV (OR = 2.09; 95 % CI, 1.02-4.28; P < 0.05; adjusted OR = 3.19; 95 % CI, 1.37-7.45; P < 0.05) and clinically severity of PV (OR = 2.71; 95 % CI, 1.09-6.72; P < 0.05; adjusted OR = 1.25; 95 % CI, 1.10-1.40; P < 0.05). But none such significant combined effect was observed between others genotype (AA and AG) and other risk factors. In conclusions, the combined effect of BDNF rs6265 genotype (GG) and higher BMI may increases the risk and clinical severity of PV in Chinese Han population.

Diet and psoriasis, part I: Impact of weight loss interventions

One of the most frequently asked questions by patients with psoriasis is whether dietary changes can improve their condition. Included in this discussion is whether dietary weight loss can benefit their skin disease. Obesity has been associated with a proinflammatory state and several studies have demonstrated a relationship between body mass index and psoriasis severity. However, the question of whether weight loss interventions can impact psoriasis outcome is less clear. Here, we review the literature to examine the efficacy of weight loss interventions, both dietary and surgical, on psoriasis disease course.