The association between GJB2 gene polymorphism and psoriasis: a verification study

Exploration of Biomarkers of Psoriasis through Combined Multiomics Analysis

Background

Aberrant DNA methylation patterns are of increasing interest in the study of psoriasis mechanisms. This study aims to screen potential diagnostic indicators affected by DNA methylation for psoriasis based on bioinformatics using multiple machine learning algorithms and to preliminarily explore its molecular mechanisms.

Methods

GSE13355, GSE14905, and GSE73894 were collected from the gene expression omnibus (GEO) database. Differentially expressed genes (DEGs) and differentially methylated region- (DMR-) genes between psoriasis and control samples were combined to obtain differentially expressed methylated genes. Subsequently, a protein-protein interaction (PPI) network was established to analyze the interaction between differentially expressed methylated genes. Moreover, the hub genes of psoriasis were screened by the least absolute shrinkage and selection operator (LASSO), Random Forest (RF), and Support Vector Machine (SVM), which were further performed single-gene gene set enrichment analysis (GSEA) to clarify the pathogenesis of psoriasis. The druggable genes were predicted using DGIdb. Finally, the expressions of hub genes in psoriasis lesions and healthy controls were detected by immunohistochemistry (IHC) and quantitative real-time PCR (RT-qPCR).

Results

In this study, a total of 767 DEGs and 896 DMR-genes were obtained. Functional enrichment showed that they were significantly associated with skin development, skin barrier function, immune/inflammatory response, and cell cycle. The combined transcriptomic and DNA methylation data resulted in 33 differentially expressed methylated genes, of which GJB2 was the final identified hub gene for psoriasis, with robust diagnostic power. IHC and RT-qPCR showed that GJB2 was significantly higher in psoriasis samples than those in healthy controls. Additionally, GJB2 may be involved in the development and progression of psoriasis by disrupting the body's immune system, mediating the cell cycle, and destroying the skin barrier, in addition to possibly inducing diseases related to the skeletal aspects of psoriasis. Moreover, OCTANOL and CARBENOXOLONE were identified as promising compounds through the DGIdb database.

Conclusion

The abnormal expression of GJB2 might play a critical role in psoriasis development and progression. The genes identified in our study might serve as a diagnostic indicator and therapeutic target in psoriasis.

Variants in PRKCE and KLC1, Potential Regulators of Type I Psoriasis

Purpose

Psoriasis is a multifactorial disease with a complex genetic predisposition. The pathophysiology of psoriasis is associated with genetic variants. To better characterize gene variants in psoriasis and identify the relationship between clinical characteristics and variant genes in its pathogenesis.

Patients and Methods

DNA was extracted and purified from eight pairs of monozygotic twins with psoriasis discordance and 282 type I psoriasis patients. Thirteen variable genes were amplified and sequenced using the Sanger method after whole genome sequencing.

Results

Thirteen genes were found to be variable in eight pairs of monozygotic twins with psoriasis discordance. Among the 13 genes, the variant frequencies of protein kinase C epsilon (PRKCE) (c.240T>C, 35.9% vs 47.7%, P < 0.05) and kinesin light chain 1 (KLC1) (c.216A>G, 2.9% vs 98.1%, P< 0.01) were significantly lower in psoriasis than in normal Asian individuals. Additionally, we found considerable differences in the relationship between variants in genes CADM2, JPH2, SPTLC3 and clinical characteristics stratified by medical history and family history. Moreover, the variants in MEGF6 (39.52% vs 22.50%, χ²=3.83, p < 0.05) showed a stronger association with the mild group (PASI ≤10) than the heavy group.

Conclusion

Our results provide a comprehensive correlation analysis of regulatory genes that are regulated in psoriasis. This integrated analysis offers novel insight into the pathogenic mechanisms involved in psoriasis.

Assessment of Gap Junction Protein Beta-2 rs3751385 Gene Polymorphism in Psoriasis Vulgaris

Background

Gap junction protein beta 2 (GJB2) upregulation in psoriasis transcriptome analysis as well as connexin 26 (Cx26, encoded by GJB2) expression upregulation in psoriatic plaques has already been substantiated. GJB2 rs72474224 and rs3751385 have been correlated with psoriasis vulgaris incidence in Chinese populations. Here we study the effect of rs3751385 in patients suffering from psoriasis vulgaris in a Caucasian Greek population at the prefecture of Thrace in Northern Greece.

Methods

One hundred and seventy-three (111 males and 62 females) psoriatic patients (108 were of early-onset psoriasis) and 171 matched controls were included in the study. Genomic DNA was extracted from peripheral blood leukocytes and genotyping was carried out by polymerase chain reaction-restriction-fragment length polymorphism (PCR-RFLP).

Results

A statistically significant lower frequency of C/T genotype in late-onset male psoriasis vulgaris (P = 0.029) as well as of T allele in female early-onset psoriasis vulgaris (P = 0.049) were ascertained.

Conclusions

On condition that all other genetic or environmental factors remain stable, the existence and possible interaction between GJB2 rs3751385 C and T alleles in male psoriatic patients may be considered as protective gene component against late-onset psoriasis appearance, while presence of the T allele in female might block the histogenetic mechanisms of early-onset psoriasis lesions.

Association of genetic polymorphism of interleukin-17A & interleukin-17F with susceptibility of psoriasis

Background & objectives:

Psoriasis is a chronic inflammatory skin disease with unknown aetiology. So far studies have confirmed that interleukins, pro-inflammatory factors and T-cell activation play major role in the development of disease. Interleukin-17 (IL-17) a T helper inflammatory cytokine, was found to be positively correlated with severity of psoriasis. However, the specific mechanism has not been clarified. IL-17A and IL-17F are group members of IL17 family cytokines and found to be located adjacent to one another on the same human chromosome, 6p12. The present study was designed to identify the association between IL-17A and IL-17F gene polymorphism with susceptibility of psoriasis in north Indian population.

Methods:

A total of 166 psoriasis patients and 150 healthy controls were genotyped for IL-17A and IL-17F gene polymorphism by amplification refractory mutation system-polymerase chain reaction method. One single nucleotide polymorphism (SNP) was analysed in IL-17A (rs10484879) and one SNP in IL-17F (rs763780) to look for an association with psoriasis.

Results:

Our study indicated decreased frequency of IL-17A (rs10484879) G allele (51.8 vs. 65.0%), and IL-17F (rs763780) C allele (36.5 vs. 45.7%) in psoriatic patients as compared to healthy controls.

Interpretation & conclusions:

The present findings suggest that IL-17A (rs10484879) G/T and IL-17F (rs763780) C/T gene polymorphisms may contribute in pathogenesis of psoriasis. Further studies need to be done to confirm these findings.

Association of the novel susceptible locus rs9266150 with clinical features of psoriasis vulgaris in the Chinese Han population

Psoriasis is a chronic multifactorial disease and is considered to be strongly associated with the major histocompatibility complex (MHC) region. We have discovered an independent, novel and susceptible psoriasis risk HLA loci, rs9266150; P = 4.52 × 10^-9 for the first time. In this study, we aimed to verify the relationship between the susceptible locus and the subphenotypes of psoriasis vulgaris (PV), including geographic location, gender, age of onset, family history and present skin lesion types (chronic plaque and guttate). To investigate the distribution and association of the rs9266150 gene with clinical phenotypes of PV in Chinese Han population, we conducted an analysis in case-control and case-only subjects in the 9906 controls and 8744 cases by MHC targeted sequencing stratified analysis in this study. Significant associations were found with a northern geographic location in the case-only (P = 1.97 × 10^-4 ) and the subphenotype-control analyses (P = 5.57 × 10^-5 ), males in the case-only (P = 4.77 × 10^-3 ) and the subphenotype-control analyses (P = 7.31 × 10^-4 ), and guttate psoriasis in the case-only (P = 4.08 × 10^-3 ) and the subphenotype-control analyses (P = 1.27 × 10^-3 ). There were no significant differences observed between the age of onset (OR = 1.062, 95% CI: 0.9725-1.16, P = 1.8 × 10^-1 ) and the family history of psoriasis (OR = 0.981, 95% CI: 0.9048-1.064, P = 6.43 × 10^-1 ). The recessive model provided the best fit for rs9266150 (P = 4.38 × 10^-7 ). Our results implied that rs9266150 might not only play an important role in the development of psoriasis, but also be positively associated with the geographic location, gender and present skin lesion in the Chinese population.

Single nucleotide polymorphism rs2274084 of gap junction protein beta 2 gene among Epstein-Barr virus-associated tumors

BACKGROUND

Gap junction protein beta 2 gene (GJB2) encodes one of connexins- Connexin 26 (Cx26), which mainly expressed in epithelial cells. Cx26 is usually considered a channel to exchange information between cells, which plays a critical role in tumor cell proliferation.

OBJECTIVE

We investigated GJB2 rs2274084 polymorphism in three types of tumors, including nasophoryngeal carcinoma (NPC), gastric cancer (GC) and lymphoma.

METHODS

Proteinase K digestion and phenolchloroform purification and QIAamp DNA FFPE tissue kit was used for DNA extraction. The genotype of GJB2 gene rs2274084 was detected through Sequenom MassARRAY SNP technique. The Chi-square test and Fisher's exact test were used to compare the differences between two groups.

RESULTS

The genotype frequency of GJB2 gene rs2274084 was significantly different between EBV-positive NPC and normal control (P< 0.05). However, for EBV-associated gastric cancer (EBVaGC), EBV-negative gastric cancer (EBVnGC) and lymphoma, no significant differences were found in comparison with the normal control.

CONCLUSIONS

The mutation rate of TT genotype was a risk factor to the occurrence of EBV-positive NPC.

Connexin Communication Compartments and Wound Repair in Epithelial Tissue

Epithelial tissues line the lumen of tracts and ducts connecting to the external environment. They are critical in forming an interface between the internal and external environment and, following assault from environmental factors and pathogens, they must rapidly repair to maintain cellular homeostasis. These tissue networks, that range from a single cell layer, such as in airway epithelium, to highly stratified and differentiated epithelial surfaces, such as the epidermis, are held together by a junctional nexus of proteins including adherens, tight and gap junctions, often forming unique and localised communication compartments activated for localised tissue repair. This review focuses on the dynamic changes that occur in connexins, the constituent proteins of the intercellular gap junction channel, during wound-healing processes and in localised inflammation, with an emphasis on the lung and skin. Current developments in targeting connexins as corrective therapies to improve wound closure and resolve localised inflammation are also discussed. Finally, we consider the emergence of the zebrafish as a concerted whole-animal model to study, visualise and track the events of wound repair and regeneration in real-time living model systems.

Molecular Mechanisms and Management of a Cutaneous Inflammatory Disorder: Psoriasis

Psoriasis is a complex chronic inflammatory cutaneous disorder. To date, robust molecular mechanisms of psoriasis have been reported. Among diverse aberrant immunopathogenetic mechanisms, the current model emphasizes the role of Th1 and the IL-23/Th17 axis, skin-resident immune cells and major signal transduction pathways involved in psoriasis. The multiple genetic risk loci for psoriasis have been rapidly revealed with the advent of a novel technology. Moreover, identifying epigenetic modifications could bridge the gap between genetic and environmental risk factors in psoriasis. This review will provide a better understanding of the pathogenesis of psoriasis by unraveling the complicated interplay among immunological abnormalities, genetic risk foci, epigenetic modification and environmental factors of psoriasis. With advances in molecular biology, diverse new targets are under investigation to manage psoriasis. The recent advances in treatment modalities for psoriasis based on targeted molecules are also discussed.

Correlation analysis of the HLA-DPB1*05:01 and BTNL2 genes within the histocompatibility complex region with a clinical phenotype of psoriasis vulgaris in the Chinese Han population

BACKGROUND

The human major histocompatibility complex (MHC) is known to be highly polymorphic and has been identified to be associated with numerous diseases. The HLA-DPB1 and BTNL2 genes were associated with psoriasis for the first time. The present study aims to investigate the relevance of the HLA-DPB1 and BTNL2 genes with respect to clinical phenotypes of psoriasis vulgaris (PV).

METHODS

To investigate whether the HLA-DPB1 and BTNL2 polymorphisms were associated with clinical phenotypes of PV in Chinese Han population, we conducted an analysis in case-controls and case-only subjects (9906 controls and 8744 cases) via MHC targeted sequencing stratified analysis.

RESULTS

In cases and controls, analysis showed that the genotype of HLA-DPB1*05:01 was associated with type of guttate [p = 3.914 × 10^-2 , odds ratio (OR = 0.9335)] and northern region (p = 1.182 × 10^-3 , OR = 0.9108). In the case-only analysis, the genotype of HLA-DPB1*05:01 was significantly correlated with geographical region (p = 1.36 × 10^-3 , OR = 1.134). In cases and controls, analysis showed that the genotype of BTNL2 (rs 41355746) was associated with being male (p = 2.563 × 10^-2 , OR = 0.8897), early-onset (p = 9.399 × 10^-3 , OR = 0.8856), guttate (p = 2.469 × 10^-2 , OR = 0.8558) and family history (p = 1.51 × 10^-4 , OR = 0.772). In the case-only analysis, the genotype of BTNL2 (rs41355746) was significantly correlated with family history (p = 1.768 × 10^-3 , OR = 0.757) and age of onset (p = 3.818 × 10^-2 , OR = 1.195).

CONCLUSIONS

The results of the present study indicate that the HLA-DPB1*05:01 gene was associated with the geographical region of PV and the BTNL2 gene was significantly associated with family history and age of onset of PV. In conclusion, the HLA-DPB1*05:01 and BTNL2 genes might be responsible for the complicacy of clinical features.

A genetic coding variant rs72474224 in GJB2 is associated with clinical features of psoriasis vulgaris in a Chinese Han population

Our recent targeted sequencing study identified a missense single-nucleotide polymorphism rs72474224 (c.324C>T) in GJB2. To investigate the correlation between rs72474224 (c.324C>T) and subphenotypes of psoriasis, genotype data for rs72474224 (c.324C>T, p.Val37Ile) was analyzed in 9946 cases and 9906 controls. The additive model provided the best fit for rs72474224 (P = 7.34 × 10(-9)). The genotypic and allelic frequency distributions were associated with plaque psoriasis in case-only (Pgenotype = 2.67 × 10(-3), Pallele = 6.22 × 10(-4)) and subphenotype-control (Pgenotype = 1.58 × 10(-11), Pallele = 8.16 × 10(-12)) analyses. No other significant difference was found in case-only analyses. Rs72474224 in GJB2 is preferentially associated with plaque psoriasis in Chinese population and might contribute to the complexity of psoriasis clinical features.

Single nucleotide polymorphisms of the GJB2 and GJB6 genes are associated with autosomal recessive nonsyndromic hearing loss

Single nucleotide polymorphisms (SNPs) are important markers in many studies that link DNA sequence variations to phenotypic changes; such studies are expected to advance the understanding of human physiology and elucidate the molecular basis of diseases. The DFNB1 locus, which contains the GJB2 and GJB6 genes, plays a key role in nonsyndromic hearing loss. Previous studies have identified important mutations in this locus, but the contribution of SNPs in the genes has not yet been much investigated. The aim of this study was to investigate the association of nine polymorphisms located within the DFNB1 locus with the occurrence of autosomal recessive nonsyndromic hearing loss (ARNSHL). The SNPs rs3751385 (C/T), rs7994748 (C/T), rs7329857 (C/T), rs7987302 (G/A), rs7322538 (G/A), rs9315400 (C/T), rs877098 (C/T), rs945369 (A/C), and rs7333214 (T/G) were genotyped in 122 deaf patients and 132 healthy controls using allele-specific PCR. There were statistically significant differences between patients and controls, in terms of allelic frequencies in the SNPs rs3751385, rs7994748, rs7329857, rs7987302, rs945369, and rs7333214 (P < 0.05). No significant differences between the two groups were observed for rs7322538, rs9315400, and rs877098. Our results suggest that SNPs present in the GJB2 and GJB6 genes may have an influence on ARNSHL in humans.

Correlation between Reversal of DNA Methylation and Clinical Symptoms in Psoriatic Epidermis Following Narrow-Band UVB Phototherapy

Epigenetic modifications by DNA methylation are associated with a wide range of diseases. Previous studies in psoriasis have concentrated on epigenetic changes in immune cells or in total skin biopsies that include stromal-associated changes. In order to improve our understanding of the role of DNA methylation in psoriasis, we sought to obtain a comprehensive DNA methylation signature specific for the epidermal component of psoriasis and to analyze methylation changes during therapy. Genome-wide DNA methylation profiling of epidermal cells from 12 patients undergoing narrow-band UVB phototherapy and 12 corresponding healthy controls revealed a distinct DNA methylation pattern in psoriasis compared with controls. A total of 3,665 methylation variable positions (MVPs) were identified with an overall hypomethylation in psoriasis patient samples. DNA methylation pattern was reversed at the end of phototherapy in patients showing excellent clinical improvement. Only 7% of phototherapy-affected MVPs (150 out of 2,108) correlate with nearby gene expression. Enrichment of MVPs in enhancers indicates tissue-specific modulation of the transcriptional regulatory machinery in psoriasis. Our study identified key epigenetic events associated with psoriasis pathogenesis and helps understand the dynamic DNA methylation landscape in the human genome.

Connexins: sensors of epidermal integrity that are therapeutic targets

Gap junction proteins (connexins) are differentially expressed throughout the multiple layers of the epidermis. A variety of skin conditions arise with aberrant connexin expression or function and suggest that maintaining the epidermal gap junction network has many important roles in preserving epidermal integrity and homeostasis. Mutations in a number of connexins lead to epidermal dysplasias giving rise to a range of dermatological disorders of differing severity. 'Gain of function' mutations reveal connexin-mediated roles in calcium signalling within the epidermis. Connexins are involved in epidermal innate immunity, inflammation control and in wound repair. The therapeutic potential of targeting connexins to improve wound healing responses is now clear. This review discusses the role of connexins in epidermal integrity, and examines the emerging evidence that connexins act as epidermal sensors to a variety of mechanical, temperature, pathogen-induced and chemical stimuli. Connexins thus act as an integral component of the skin's protective barrier.

Angiotensin-converting enzyme insertion/deletion polymorphism and susceptibility to psoriasis in a Chinese population

INTRODUCTION

The relationship between the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and psoriasis has previously been studied mainly in Caucasians and only once in Asians. The aim of this study is to evaluate the association between the ACE I/D polymorphism and the risk of psoriasis in a Chinese population.

MATERIALS AND METHODS

The study population consisted of 668 psoriasis patients and 668 matched control subjects. The ACE I/D gene polymorphism was analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The frequency of the ACE II genotype (odds ratio (OR) = 1.32, 95% confidence interval (CI) = 1.06, 1.63; P = 0.01) and I allele (OR = 1.25, 95% CI = 1.06, 1.48; P = 0.01) in patients with psoriasis was significantly higher than that in the control group. And the D allele frequency in patients with psoriasis was significantly lower (OR = 0.80, 95% CI = 0.68, 0.95; P = 0.01) than that in the control group. When stratified by family history, the frequency of the DD genotype was marginally significantly lower in patients with a positive family history of psoriasis (familial psoriasis) than in those with negative (sporadic psoriasis) (OR = 0.47, 95% CI = 0.23, 0.97; P = 0.04). When stratified by onset of the disease, type of psoriasis and the severity of psoriasis, no statistically significant result was observed.

CONCLUSION

Our study suggested that the ACE II genotype and I allele might confer susceptibility to psoriasis in a Chinese population.