Impact of TNF haplotypes in the physical course of acne vulgaris

In severe acne vulgaris, TNF-α gene variants are connected to increased TNF-α gene expression and insulin resistance

BACKGROUND

Acne vulgaris (AV) is a chronic inflammatory skin condition affecting the pilosebaceous unit, commonly presenting as comedones, papules, pustules, or nodules on the face, upper limbs, torso, and back, with comedones formation being the primary pathology leading to disfiguring inflammation, hyperpigmentation, scarring, and psychological impact.

AIM

The purpose of this study was to investigate the significance of two genetic variants in the promoter region of the tumor necrosis factor-alpha (TNF-α) gene and their association with insulin resistance (IR) in acne patients. To understand how these variants contribute to AV and its associated IR.

SUBJECTS AND METHODS

An analytical cross-sectional study with a case-control design and research evaluation was carried out on 87 AV patients and 73 healthy volunteers. The medical histories of both groups were obtained, as well as the severity and duration of inflammation among acne sufferers, as well as demographic data. Biochemical analysis was performed on both sets of participants, including fasting blood glucose levels, insulin levels while fasting, IR, and serum TNF-α. PCR-RFLP analysis identified -863 G > A (rs1800630) and -308 G > A (rs1800629) variations, and real-time PCR analysis evaluated TNF-α gene expression in both patients and healthy people.

RESULTS

Acne patients exhibited significantly higher levels of IR, fasting glucose, fasting insulin, serum TNF-α, and TNF-α folding change, when compared to healthy controls. The co-dominant model for -863 G > A and -308 G > A variants exhibited significant variations between the two groups. Severe acne patients who had the A/A genotype for -308 variants exhibited higher levels of IR, serum TNF-α, and TNF-α folding change. Highly significant positive linear correlation between IR, serum TNF-α, and TNF-α folding change in severe AV.

CONCLUSION

There is a correlation between AV, especially severe acne, and the -863 G > A and -308 G > A polymorphism, which influences TNF-α gene expression and serum TNF-α levels.

Genetic Variants Associated with Acne Vulgaris

Acne vulgaris (AV) ranks among the common chronic inflammatory disorders that impact the sebaceous components of hair follicles. Acne vulgaris is characterised by cardinal manifestations such as the presence of pimples, nodules, pustules, and cysts, which have the potential to lead to the development of acne scarring and pigmentation. The phenomenon is influenced by polygenic inheritance or can be ascribed to the interplay between multiple genes and environmental factors. In recent years, some researchers have found that some genes (such as IL, TNF, RETN, CYP family, MMPs and TIMPs genes et al) are associated with acne vulgaris and may affect the progression and prognosis of the disease. The number of reviews addressing acne-associated genetic variants, however, is limited. In that case, we have compiled a list of prevalent genes associated with acne in recent times. This helps us understand acne's genetic basis and lets us step in early for people prone to severe acne, lowering the chance of acne scars.

The Role of Skin Immune System in Acne

Acne vulgaris is a skin disease that often occurs in adolescence and in young adulthood. The main pathogenic factors are hyperkeratinization, obstruction of sebaceous glands, stimulation of sebaceous gland secretion by androgens, and bacterial colonization of sebaceous units by Cutibacterium acnes, which promotes inflammation. Little is known about the role of skin immune cells in the development of acne lesions. The aim of the study was to try to understand the role of skin immune cells in the course of acne. Recent studies have shown that there are at least four major pathways by which Cutibacterium acnes interacts with the innate immune system to induce inflammation: through TLRs, activating inflammasomes, inducing the production of matrix metalloproteinases (MMPs), and stimulating antimicrobial peptide (AMP) activity. Cells of adaptive immune response, mainly Th1 and Th17 lymphocytes, also play an important role in the pathogenesis of acne. It is worth emphasizing that understanding the role of the skin’s immune cells in the pathogenesis of acne may, in the future, contribute to the application of modern therapeutic strategies that would avoid addiction to antibiotics, which would alleviate the spectrum of resistance that is now evident and a current threat.

Gene variants associated with acne vulgaris presentation and severity: a systematic review and meta-analysis

BACKGROUND

Multiple factors have been attributed to acne vulgaris predisposition and individual variations in the severity of skin symptoms, and genetics stood out as one of the major factors.

METHODS

We performed a systematic review on the genes and their variants that have been investigated for association with acne presentation and severity. A random-effect meta-analysis using the allele model (minor allele vs. major allele) was also conducted to provide an overall estimation of risk effects of frequently reported gene variants. This included a subset data of 982 acne cases and 846 controls extracted from our existing GWAS database on various allergic and skin diseases among Singapore Chinese.

RESULTS

Systematic review of 51 articles covering Asians and Caucasians found 60 genes/loci and their 100 variants implicated in acne; majority of them were in the intron, coding region/missense, and promoter regions. The commonly studied candidate genes/gene families include tumor necrosis factor (TNF), and the interleukin (IL) and cytochrome P450 (CYP) gene families. Our meta-analysis showed that most of the analyzed gene variants exhibited insignificant pooled odds ratio (pOR) and significant heterogeneity between studies. Nevertheless, we found that TNF rs1800629 A allele carriers and CYP17A1 rs743572 T allele carriers had significantly reduced mild acne risk [pOR: 0.60; 95% Confidence Interval (CI): 0.33-0.86] and severe acne risk (pOR: 0.59; 95% CI: 0.40-0.79), respectively, across populations. Overall, FST (follistatin) rs629725 A allele poses a significantly modest increased risk for acne presentation (pOR: 1.19, 95% CI: 1.14, 1.23), but neither TIMP2 (TIMP metallopeptidase inhibitor 2) rs8179090 nor CYP1A1 rs4646903 (pOR: 0.96, 95% CI: 0.80-1.12; pOR: 0.95, 95% CI: 0.83, 1.08), respectively. We discovered 15 novel SNPs in the 3' UTR region of the Toll-like Receptor 4 gene (TLR4) associated with acne presentation.

CONCLUSIONS

This systematic review and meta-analysis suggest that genes influencing inflammatory responses, specifically TNF, and genes influencing the function and activity of sebaceous glands, specifically CYP17A1 and FST, have potential risk variants for acne presentation and severity across populations. Understanding the genetic susceptibility factors and biological pathways involved in the pathogenesis of acne will help us to gain insights into developing effective acne treatments.

Association of the TNF-α gene promoter polymorphisms at nucleotide -238 and -308 with acne susceptibility: a meta-analysis

BACKGROUND

The tumour necrosis factor (TNF)-α -238 and -308 polymorphisms are potential candidate genes that may serve as modulators in susceptibility to acne.

AIM

We performed a meta-analysis of case-control studies to assess the association of the TNF-α -238 and -308 polymorphisms with acne susceptibility.

METHODS

The PubMed, EMBASE, Scopus, SinoMed and China National Knowledge Infrastructure databases were systematically searched to identify eligible studies. OR and 95% CI were calculated to evaluate the association.

RESULTS

We identified seven independent case-control studies up to September 2017. The results revealed an association between the A allele of the TNF-α -238 polymorphism and increased susceptibility to acne in Asian (OR = 1.61, 95% CI 1.08-2.40) but not in European (OR = 1.10, 95% CI 0.63-1.93) populations. For the TNF-α -308 polymorphism, the minor A allele was associated with increased acne susceptibility in Asian (OR = 1.93, 95% CI 1.15-3.24) and Turkish (OR = 4.14, 95% CI 2.25-7.61) populations, but not in European (OR = 1.17, 95% CI 0.66-2.06) or Arab (OR = 0.88, 95% CI 0.64-1.22) populations. Egger test found no evidence of publication bias.

CONCLUSION

Our findings suggest that the TNF-α -238 A allele is associated with increased susceptibility to acne in Asian but not in European populations, while the TNF-α -308 A allele is associated with increased susceptibility to acne in Asian and Turkish populations but not in European or Arab populations.

Tumor necrosis factor α-308 G/A and interleukin 1 β-511 C/T gene polymorphisms in patients with scarring acne

BACKGROUND

Acne is a chronic inflammatory skin disorder which may heal with scarring. Tumor necrosis factor alpha (TNF α) and interleukin 1 β (IL-1β) are considered as the main responsible proinflammatory mediators of acne pathogenesis. Oversecretion of these cytokines was found to be associated with TNF α-308 G>A and IL-1β-511 C<T polymorphisms.

AIM

To evaluate the association of TNF α-308 and IL-1β-511 gene polymorphisms with acne and postacne scarring susceptibility and acne severity.

METHODS

Study subjects included 90 patients with acne vulgaris (31 males, 59 females; mean age: 19.6 ± 3.7 years) and 30 healthy controls (11 males, 19 females; mean age: 19.2 ± 5.1 years). Patients were sub-grouped on the basis of acne severity into mild, moderate, and severe acne groups and on the presence postacne scarring into scarring acne and nonscarring acne groups. Peripheral venous blood samples were obtained for performing real-time PCR analysis for detecting TNF α-308 and IL-1β-511 genotypic variants.

RESULTS

Among patients, 21.7% (n = 26) had mild, 22.5% (n = 27) had moderate, 30.8% (n = 37) had severe, and 30% (n = 36) had scarring acne. Genotypic variants of TNF α-308 and IL-1β-511 did not statistically differ between acne patients and controls (P values: .245 and .466). When compared in terms of acne severity and the presence of postacne scarring, no statistical significance was observed regarding frequencies of genotypic variants related to the both TNF α-308 and IL-1β polymorphisms (P > .05).

CONCLUSION

TNF α-308 and IL-1β polymorphic variants are not associated with acne and postacne scarring susceptibility and acne severity.

Genetic architecture of acne vulgaris

Acne vulgaris is a ubiquitary skin disease characterized by chronic inflammation of the pilosebaceous unit resulting from bacterial colonization of hair follicles by Propionibacterium acnes, androgen-induced increased sebum production, altered keratinization and inflammation. Here, we review our current understanding of the genetic architecture of this intriguing disease. We analysed genomewide association studies (GWAS) and candidate genes studies for acne vulgaris. Moreover, we included GWAS studies for the associated disease polycystic ovary syndrome (PCOS). Overall, the available data revealed sixteen genetic loci flagged by single nucleotide polymorphisms (SNPs), none of which has been confirmed yet by independent studies. Moreover, a GWAS for PCOS identified 21 susceptible loci. The genetic architecture is complex which has been revealed by GWAS. Further and larger studies in different populations are required to confirm or disprove results from candidate gene studies as well to identify signals that may overlap between different populations. Finally, studies on rare genetic variants in acne and associated diseases like PCOS may deepen our understanding of its pathogenesis.

Association between tumour necrosis-α gene polymorphisms and acne vulgaris in a Pakistani population

BACKGROUND

The cytokine tumour necrosis factor (TNF)-α is a well-studied potent candidate mediator that is systemically involved in a variety of inflammatory diseases. Several single nucleotide polymorphisms (SNPs) of the TNF-α gene have been studied with regard the pathogenesis of acne vulgaris, but the results have been inconclusive.

AIM

This case-control study investigated the association of the TNF -308 G>A and -238 G>A SNPs with acne vulgaris in a high-risk Pakistani population.

METHODS

In total, 160 healthy controls and 140 patients with acne were enrolled in this study. Polymorphisms were determined by PCR and restriction fragment length polymorphism analysis.

RESULTS

Our data showed that the TNF -308 G>A and TNF -238 G>A SNPs were present at a significantly higher rate in cases than in controls (P < 0.01 and P < 0.02; respectively). There was a significant difference between the G and A alleles from patients with acne and controls for -308 G>A (OR = 1.5, 95% CI = 1.07-2.19, P < 0.02) and -238 G>A (OR=1.6, 95% CI = 1.06-2.44, P = 0.02) genotype. Moreover, the severity of acne was significantly associated with TNF genotype (TNF -308 G>A: χ² = 34.6, P < 0.001; TNF -238 G>AL χ² = 12.9, P < 0.01).

CONCLUSION

Our data suggest that the TNF -308 G>A and TNF -238 G>A SNPs may contribute to the pathogenesis of acne in the study population. Furthermore, patients with severe acne showed an increased frequency of mutant TNF genotypes at -308 and -238 compared with patients with less severe acne.

Association of TNF-alpha, IL-6 and IL-1beta gene polymorphisms with polycystic ovary syndrome: a meta-analysis

Background

Several studies on the association of TNF-alpha (−308 G/A), IL-6 (−174 G/C) and IL-1beta (−511 C/T) polymorphisms with polycystic ovary syndrome (PCOS) risk have reported conflicting results. The aim of the present study was to assess these associations by meta-analysis.

Results

A total of 14 eligible articles (1665 cases/1687 controls) were included in this meta-analysis. The results suggested that there was no obvious association between the TNF-alpha (−308 G/A) polymorphism and PCOS in the overall population or subgroup analysis by ethnicity, Hardy–Weinberg equilibrium (HWE) in controls, genotyping method, PCOS diagnosis criteria, and study sample size. Also, no obvious association was found between the TNF-alpha (−308 G/A) polymorphism and obesity in patients with PCOS (body mass index [BMI] ≥ 25 kg/m² vs. BMI < 25 kg/m²). Regarding the IL-6 (−174 G/C) polymorphism, also no association was found in the overall population in heterozygote comparison, dominant model, and recessive model. Even though an allelic model (odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.41–0.96) and a homozygote comparison (OR = 0.52, 95% CI = 0.30–0.93) showed that the IL-6 (−174 G/C) polymorphism was marginally associated with PCOS. Further subgroup analysis suggested that the effect size was not significant among HWE in controls (sample size ≤ 200) and genotyping method of pyrosequencing under all genetic models. Similarly, there was no association between the IL-1beta (−511 C/T) polymorphism and PCOS in the overall population or subgroup analysis under all genetic models. Furthermore, no significant association was found between the IL-1beta (−511 C/T) polymorphism and several clinical and biochemical parameters in patients with PCOS.

Conclusions

The results of this meta-analysis suggest that the TNF-alpha (−308 G/A), IL-6 (−174 G/C), and IL-1beta (−511 C/T) polymorphisms may not be associated with PCOS risk. However, further case–control studies with larger sample sizes are needed to confirm our results.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-015-0165-4) contains supplementary material, which is available to authorized users.