Diabetes and Psoriasis: Different Sides of the Same Prism

Genome‑wide association study and polygenic risk scores predict psoriasis and its shared phenotypes in Taiwan

Psoriasis is a chronic inflammatory dermatological disease, and there is a lack of understanding of the genetic factors involved in psoriasis in Taiwan. To establish associations between genetic variations and psoriasis, a genome‑wide association study was performed in a cohort of 2,248 individuals with psoriasis and 67,440 individuals without psoriasis. Using the ingenuity pathway analysis software, biological networks were constructed. Human leukocyte antigen (HLA) diplotypes and haplotypes were analyzed using Attribute Bagging (HIBAG)‑R software and chi‑square analysis. The present study aimed to assess the potential risks associated with psoriasis using a polygenic risk score (PRS) analysis. The genetic association between single nucleotide polymorphisms (SNPs) in psoriasis and various human diseases was assessed by phenome‑wide association study. METAL software was used to analyze datasets from China Medical University Hospital (CMUH) and BioBank Japan (BBJ). The results of the present study revealed 8,585 SNPs with a significance threshold of P<5x10‑8, located within 153 genes strongly associated with the psoriasis phenotype, particularly on chromosomes 5 and 6. This specific genomic region has been identified by analyzing the biological networks associated with numerous pathways, including immune responses and inflammatory signaling. HLA genotype analysis indicated a strong association between HLA‑A*02:07 and HLA‑C*06:02 in a Taiwanese population. Based on our PRS analysis, the risk of psoriasis associated with the SNPs identified in the present study was quantified. These SNPs are associated with various dermatological, circulatory, endocrine, metabolic, musculoskeletal, hematopoietic and infectious diseases. The meta‑analysis results indicated successful replication of a study conducted on psoriasis in the BBJ. Several genetic loci are significantly associated with susceptibility to psoriasis in Taiwanese individuals. The present study contributes to our understanding of the genetic determinants that play a role in susceptibility to psoriasis. Furthermore, it provides valuable insights into the underlying etiology of psoriasis in the Taiwanese community.

Impact of Obesity on the CCR6-CCL20 Axis in Epidermal γδ T Cells and IL-17A Production in Murine Wound Healing and Psoriasis

Obesity is associated with comorbidities including type 2 diabetes, chronic nonhealing wounds and psoriasis. Normally skin homeostasis and repair is regulated through the production of cytokines and growth factors derived from skin-resident cells including epidermal γδ T cells. However epidermal γδ T cells exhibit reduced proliferation and defective growth factor and cytokine production during obesity and type 2 diabetes. One of the genes modulated in epidermal γδ T cells during obesity and type 2 diabetes is CCR6, which is the receptor for CCL20. CCL20 is elevated in the skin during obesity and type 2 diabetes. Here we identify a subset of murine epidermal γδ T cells that expresses CCR6 in response to activation in vitro and post-wounding or psoriasis induction with imiquimod in vivo. We show that CCL20 stimulates epidermal γδ T cells to produce IL-17 suggesting CCR6 regulates the IL-17 axis as in dermal γδ T cells. Further, epidermal γδ T cells upregulate CCR6 and produce IL-17 during murine models of wound repair and psoriasis. Obesity increases CCR6 and IL-17 expression by epidermal γδ T cells during wound repair but has less of an effect during psoriasis. These findings have novel implications for the regulation of a specific population of IL-17-producing epidermal γδ T cells during skin damage and inflammation.

Exploring the molecular mechanism underlying the psoriasis and T2D by using microarray data analysis

Although a large number of evidence has identified that psoriasis is significantly correlated with type 2 diabetes (T2D), the common molecular mechanism of its occurrence remains unclear. Our study aims to further elucidate the mechanism of the occurrence of this complication. We obtained the gene expression data of psoriasis (GSE30999) and T2D (GSE28829) from the Gene Expression Omnibus (GEO) dataset. Then the common differentially expressed genes (DEGs) of T2D and psoriasis were identified. After that, we performed three types of analyses about these DEGs, including functional enrichment analysis, protein-protein interaction (PPI) network and module manufacture, hub genes identification and co-expression analysis. 132 common DEGs (14 upregulated genes and 118 downregulated genes) were identified for subsequent a series of analyses. Function enrichment analysis demonstrated that Rap1 signaling pathway, PI3K-Akt signaling pathway, and cGMP-PKG signaling pathway may play a significant role in pathogenesis of psoriasis and T2D. Finally, 3 important hub genes were selected by utilizing cytoHubba, including SNRPN, GNAS, IGF2. Our work reveals the potential common signaling pathways of psoriasis and T2D. These Hub genes and common signaling pathways provide insights for further investigation of molecular mechanism about psoriasis and T2D.

Metabolic Disorders and Psoriasis: Exploring the Role of Nutritional Interventions

(1) Background: Psoriasis is a chronic autoimmune disease with a close relationship with metabolic diseases such as obesity, diabetes, and dyslipidemia. The aim of this review was to identify the relationship between psoriasis, metabolic diseases, and dietetic therapies. According to recent findings, there is a strong association between psoriasis and obesity as well as vitamin D and micronutrient deficiencies. (2) Methods: This review was conducted via PubMed, aiming to search for studies involving psoriasis linked with metabolic disorders or with nutritional treatments. (3) Results: Our review shows that a healthy lifestyle can positively influence the course of the disease. The maintaining of a proper body weight together with physical activity and good nutritional choices are associated with an improvement in psoriasis severity. A Mediterranean diet rich in fiber, vitamins, and polyphenols may indeed be a strategy for controlling psoriasis symptoms. The effectiveness of this diet lies not only in its anti-inflammatory power, but also in its ability to favorably influence the intestinal microbiota and counteract dysbiosis, which is a risk factor for many autoimmune diseases. (4) Conclusions: In synergy with standard therapy, the adoption of an appropriate diet can be recommended to improve the clinical expression of psoriasis and reduce the incidence of comorbidities.

Periodontal disease does not increase the risk of subsequent psoriasis

Previous studies suggested that chronic periodontitis may be a risk factor for psoriasis. However, no study has confirmed this relationship for all stages of periodontal disease (gingivitis and periodontitis). This nationwide population-based retrospective cohort study aimed to investigate whether periodontal disease is an independent risk factor for the development of subsequent psoriasis. Patients aged ≥ 20 years who underwent both medical and oral checkups from the National Health Screening Program between 2002 and 2007 were selected from a customized database provided by the National Health Insurance Service (NHIS). Then, patients with periodontal disease (n = 3,682,468) and without periodontal disease (control, n = 3,637,128) according to oral examination results were identified. We tracked each patient for subsequent psoriasis diagnosis until the end of 2018 using NHIS database. The incidence rates of psoriasis per 1000 person-years were 0.36 and 0.34 in the periodontal disease group and control groups, respectively. After adjusting for potential cofactors, no significant increase in risk (adjusted hazard ratio, 0.994; 95% confidence interval, 0.974-1.015) was observed. Similar results were observed when analyzing the risk of psoriasis in patients who required scaling or periodontal surgery. In conclusion, periodontal disease is not an independent risk factor of psoriasis.

Advanced Glycation End Products and Psoriasis

Advanced glycation end products (AGEs) are biologically active compounds formed physiologically throughout a sequence of chemical reactions, to generate highly oxidant-reactive aldehydes that combine covalently to proteins. They accumulate slowly in tissues during ageing but also in metabolic and selected inflammatory disorders. Accumulation of AGEs occurs more rapidly and intensely in the skin and serum of patients with type 2 diabetes, obesity, cardiovascular diseases, chronic renal insufficiency, and non-alcoholic fatty liver disease and also in the skin of patients with psoriasis. All of the above conditions are intimately associated with psoriasis. Interaction of AGEs with their receptors (RAGEs) stimulates cellular signaling with the formation of reactive oxygen species and activation of nuclear factor kappa light chain enhancer of activated B (NF-kB), which is a key regulator in the expression of inflammatory mediators and the production of oxidative stress. Thus, AGEs may play an interesting pathogenic role in the intersection of inflammatory and metabolic diseases, may represent a biomarker of inflammation and a potential target for novel therapeutic strategies. This is a narrative review with the objective to summarize current evidence on the role of AGEs in psoriasis.

Exploring disease comorbidities and temporal disease progression of psoriasis: an observational, retrospective, multi-database, cohort study

BACKGROUND

Comorbidities associated with psoriasis are well documented. However, few studies have explored the comorbidity trajectories that patients with psoriasis commonly experience over time. This study reports the 5-year comorbidity trajectories of patients with psoriasis.

OBJECTIVES

To determine the long-term comorbidity trajectories of patients with psoriasis in Denmark.

METHODS

This observational cohort study explored the Danish National Patient Registry (DNPR) between 1999 and 2013 to identify comorbidities diagnosed 5 years prior to or after a psoriasis diagnosis. Comorbidity occurrence in patients with psoriasis (psoriasis cohort) was compared with patients without psoriasis (the N group). Comparison groups, each the same size as the psoriasis cohort, were created by selecting random patients from the N group. If a comorbidity occurrence was higher in more than nine comparison groups than in the psoriasis cohort, it was not analysed and only comorbidities that occurred in ≥ 0·8% of the psoriasis cohort were analysed. The strength of association between a psoriasis diagnosis and a comorbidity diagnosis was measured using relative risk (RR). All psoriasis and comorbidity pairs that achieved RR > 1 (P < 0·001) (known as a Diagnosed Pair) were tested for directionality to identify the sequence of diagnoses using a binomial test. Diagnosed Pairs with a statistically significant direction (Bonferroni corrected P-value < 0·025) were then used to create comorbidity trajectory clusters 5 years before and after a psoriasis diagnosis.

RESULTS

A total of 17 683 patients with psoriasis were compared with 10 000 comparison groups. A total of 121 comorbidities met the minimum criteria that ≥ 0·8% of the psoriasis cohort were diagnosed with the comorbidity within 5 years (before or after) of their psoriasis diagnosis. Thirty-eight of these comorbidities achieved RR > 1 (P < 0·001) with psoriasis, of which 19 achieved a significant direction from psoriasis to a comorbidity (including psoriasis to hypothyroidism), and four achieved a significant direction from a comorbidity diagnosis to a psoriasis diagnosis (including Crohn disease to psoriasis); four of five comorbidity trajectories with three sequential diagnoses achieved an RR > 1 (P < 0·001) and a significant direction from psoriasis to the first comorbidity to the second comorbidity (including psoriasis to hypertension to atrial fibrillation and flutter).

CONCLUSIONS

Comorbidity trajectories may support clinicians in conducting disease risk analyses of patients with psoriasis and help plan optimal treatment to prevent future high-risk comorbidities.

Bacterial Metabolites: A Link between Gut Microbiota and Dermatological Diseases

Dysbiosis has been identified in many dermatological conditions (e.g., psoriasis, atopic dermatitis, systemic lupus erythematosus). One of the ways by which the microbiota affect homeostasis is through microbiota-derived molecules (metabolites). There are three main groups of metabolites: short-chain fatty acids (SCFAs), tryptophan metabolites, and amine derivatives including trimethylamine N-oxide (TMAO). Each group has its own uptake and specific receptors through which these metabolites can exert their systemic function. This review provides up-to-date knowledge about the impact that these groups of gut microbiota metabolites may have in dermatological conditions. Special attention is paid to the effect of microbial metabolites on the immune system, including changes in the profile of the immune cells and cytokine disbalance, which are characteristic of several dermatological diseases, especially psoriasis and atopic dermatitis. Targeting the production of microbiota metabolites may serve as a novel therapeutic approach in several immune-mediated dermatological diseases.

Mitochondrial dysfunction: The pathological link between psoriasis and insulin resistance?

BACKGROUND

Psoriasis is strongly associated with insulin resistance (IR). Lipid profile disturbances and upregulation of enzymes crucial for fatty acid oxidation have been reported in patients with psoriasis. Mitochondrial ß-oxidation is altered in patients with IR. Common mitochondrial dysfunction may be involved in the origin of both diseases.

OBJECTIVE

This study aimed to evaluate mitochondrial ß-oxidation, intermediary metabolism, and mitochondrial content in psoriatic patients with or without IR and compare them to healthy controls.

METHODS

The participants were divided into three groups: (1) psoriasis and IR (n = 26); (2) psoriasis without IR (n = 17); and (3) healthy controls (n = 17). Quantification of amino acids and acylcarnitines (AC) by tandem mass spectrometry, determination of urinary organic acids by gas chromatography/mass spectrometry (GC/MS), and mitochondrial DNA quantification were performed in all groups.

RESULTS

When comparisons were made between the two psoriatic groups, no differences were found between: C5DC + C6OH, C16:1, Met/Leu, Met/Phe, C16:1/C16, and C5DC + C6OH/C4DC + C5OH ratios. Nine analytes were different: phenylalanine, Cit/Phe, and Cit/Tyr ratios, C0, C3, C5, C6DC, C16, and C18:1OH. There were no correlations between psoriasis area and severity index (PASI), body mass index (BMI) and duration of disease with ACs. A higher proportion of patients with psoriasis showed increased urine levels of uric acid and hippuric acid (p = 0.01). The mtDNA content was significantly higher in cases than in controls, with no differences between IR and non-IR psoriatic patients.

CONCLUSIONS

Psoriasis patients with and without IR have a different acylcarnitine profile reflecting impaired ß-oxidation. A distinctive profile of acylcarnitines suggests an involvement of mitochondrial function associated with an increase in stearoyl CoA desaturase (SCD) activity in psoriatic patients with and without IR.

An Emerging Role of Proanthocyanidins on Psoriasis: Evidence from a Psoriasis-Like Mouse Model

Background

Psoriasis is an immune-mediated, chronic inflammatory disease, and genetic, immune, oxidative stress (OS), and environmental factors are all thought to contribute to its occurrence. Proanthocyanidins (PCs) are natural flavonoids consisting of catechins and epicatechins which have anti-inflammatory and anti-OS activities. PCs have been widely used to treat various diseases, but reports regarding psoriasis are rare.

Objective

To investigate the therapeutic effect and potential mechanisms of action of PCs in a psoriasis-like mouse model.

Methods

Thirty male BALB/c hairless mice were assigned to six groups (n = 5): normal, model, low-dose PCs, medium-dose PCs, high-dose PCs, and control groups. The final five groups were dorsally exposed to 5% imiquimod (IMQ) cream once a day for 6 consecutive days, while the normal group received no intervention. Following the first day of IMQ application, mice in the PC-treated group were dosed with different amounts of PCs daily by oral gavage for six days, whereas mice in the control group received normal saline in the same way. One week later, skin lesions were evaluated by the severity of scoring system based on psoriasis area and severity index (PASI), and pathological alterations were assessed by hematoxylin-eosin (HE) staining. Indicators of inflammation or OS, such as interleukin- (IL-) 17, IL-23, phosphorylated-phosphatidylinositol 3-kinase (p-PI3K), phosphorylated-signal transducer and activator of transcription 3 (p-STAT3), superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), catalase (CAT), vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS), and heme oxygenase-1 (HO-1), were determined by ELISA, RT-PCR, western blot, and immunohistochemistry (IHC) analysis.

Results

IMQ administration induced the formation of large dark red plaques with thickly layered scales on the dorsal skin of mice; nevertheless, the lesions were substantially alleviated by PC administration. Histopathological alterations were observed in both model and control groups with epidermal hyperkeratosis, granulosa layer thinning, acanthosis, downward extension of rete ridges, dermal papillae expansion, capillary hyperplasia, and infiltration by inflammatory cells around blood vessels. These pathological changes, however, were restored by a range of doses of PCs, high-dose PCs in particular. Different doses of PCs significantly lowered the spleen index, levels of inflammatory or oxidative proteins (IL-17, IL-23, MDA, ROS, p-PI3K, and p-STAT3), and the mRNA expression of Il-17, Il-23, Vegf, and iNos. Protein and mRNA levels of anti-OS and anti-inflammatory biomarkers, including SOD, CAT, GSH, and HO-1, greatly increased after PC treatment, especially at the highest dose.

Conclusions

Our findings reveal that PCs ameliorate psoriasis-like symptoms, suppressing the inflammatory response and mitigating OS damage in an IMQ-induced psoriasis-like mouse model. These effects are probably related to the inactivation of STAT3 and PI3K and activation of HO-1 signaling.

Activation of the STING-IRF3 pathway involved in psoriasis with diabetes mellitus

Psoriasis and type 2 diabetes mellitus (T2DM) share similar inflammatory pathways in their pathogenesis. The stimulator of interferon genes (STING)‐interferon regulatory factor 3 (IRF3) pathway has recently been shown to play an important role in immune and metabolic diseases. In this study, we investigated the activation of the STING‐IRF3 pathway in human immortalized keratinocytes (HaCaT) cells treated with palmitic acid (PA) and imiquimod (IMQ). Additionally, we detected the STING‐IRF3 pathway in diabetic mice with imiquimod (IMQ)‐induced psoriasis and assessed the potential of STING inhibitor C‐176. Furthermore, skin samples from patients with psoriasis and diabetes were collected for immunohistochemical analysis. The results indicated that the STING‐IRF3 pathway was activated in HaCaT cells. Moreover, the STING pathway was also found to be induced in the skin tissue of diabetic mice with psoriasis; the inflammatory responses were ameliorated by treatment with C‐176. In the skin tissue samples of patients with psoriasis and diabetes, immunohistochemistry showed that the expression levels of STING and phosphorylated IRF3 were also significantly increased. Thus, we conclude that the STING‐IRF3 pathway is involved in the inflammatory response in the manifestation of psoriasis with T2DM. Inhibition of the activation of the STING pathway can ameliorate the development of psoriasis in diabetes and could be targeted for the development of therapeutic agents for these conditions.

Clinical effects of antidiabetic drugs on psoriasis: The perspective of evidence-based medicine

Psoriasis and diabetes shared common underlying pathophysiological mechanisms. Emerging data suggested that antidiabetic medications may improve the psoriasis severity in patients with diabetes mellitus. Several hypoglycemic agents including thiazolidinediones, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, and biguanides have been reported to make a remarkable reduction in the Psoriasis Area and Severity Index score from baseline. This antipsoriatic effect could be mediated not only by the glucose-lowering action of these agents but also via inhibition of keratinocyte over proliferation, increase expression of differentiation markers, suppression the immune inflammatory pathway, and blocking the calcium channels and mitogen-activated protein kinase signaling pathways. On the other hand, there was no significant increase in adverse reactions associated with the treatment of pioglitazone or metformin. However, previous studies often had the relatively short duration of the trials, and did not have enough power to assess recurrence of psoriasis. Potential bias in the study and missing data could undermine the reliability of the results. Therefore, the appropriately randomized controlled studies with large sample sizes and long-term durations in various psoriasis patients are warranted for further support.

Is Metformin a Possible Beneficial Treatment for Psoriasis? A Scoping Review

Psoriasis is a chronic inflammatory condition with genetic, immunological, and metabolic etiology. The link between psoriasis and diabetes mellitus has been shown in genetic predisposition, environmental influences, inflammatory pathways, and insulin resistance, resulting in end-organ damage in both conditions. Because comorbidities often accompany psoriasis, the therapeutic management of the disease must also take into consideration the comorbidities. Given that metformin’s therapeutic role in psoriasis is not yet fully elucidated, we raised the question of whether metformin is a viable alternative for the treatment of psoriasis. We conducted this scoping review by searching for evidence in PubMed, Cochrane, and Scopus databases, and we used an extension for scoping reviews (PRISMA-ScR). Current evidence suggests that metformin is safe to use in psoriasis. Studies have shown an excellent therapeutic response to metformin in patients with psoriasis and comorbidities such as diabetes, metabolic syndrome, and obesity. There is no clear evidence supporting metformin monotherapy in patients with psoriasis without comorbidities. There is a need to further evaluate metformin in larger clinical trials, as a therapy in psoriasis.