Association between interleukin 18 polymorphisms and alopecia areata in Koreans

Interleukin gene polymorphisms and alopecia areata: A systematic review and meta-analysis

BACKGROUND

Alopecia areata (AA) is an autoimmune disease which results in non-scarring hair loss on the scalp or any surface with hair. Several genetic polymorphisms of the interleukin genes have been linked with this disease but the results are inconsistent. This systematic review and meta-analysis were done to find the association between rs3118470, rs2275913, rs3212227, and rs10889677 of the IL2RA, IL17A, IL12B, and IL23R genes, respectively, of the interleukin family with alopecia areata.

METHODS

A comprehensive search for relevant research articles was conducted in Pubmed, Google Scholar, and Embase databases. Our search yielded 8 relevant articles with 1940 cases and 1788 controls. The odds ratio with 95% confidence intervals was calculated using fixed effect and random effect models. Heterogeneity was determined using the Q-test and I2 test. Publication bias was determined and funnel plots were used to adjust the odds ratio.

RESULTS

We found a significant risk effect for rs3118470 of the IL2RA gene with alopecia areata in the dominant model (CC + CT vs TT; OR = 1.54, 95% confidence interval = 1.05-2.26, P < .05, I2 = 69.03%) and homozygous model (CC vs TT; OR = 2.00, 95% confidence interval = 1.07-3.71, P < .05, I2 = 72.84%). For the other single nucleotide polymorphisms, we could not find any statistically significant association with the disease.

CONCLUSION

Our analysis showed that mutation of rs3118470 of IL2RA gene possesses a significant risk effect for alopecia areata. Future studies with larger sample sizes and ethnic backgrounds are warranted to confirm our findings.

Clinical and Genetic Aspects of Alopecia Areata: A Cutting Edge Review

Alopecia areata (AA) is a chronic, non-scarring, immune-mediated skin disease that affects approximately 0.5-2% of the global population. The etiology of AA is complex and involves genetic and environmental factors, with significant advancements in genetic research occurring in recent years. In addition to well-known genes such as PTPN22, CTLA4, and IL2, which have been widely supported as being associated with AA, an increasing number of specific gene-related loci have been discovered through advances in genetic research. For instance, gene analysis of microRNAs can reveal the critical role of miRNAs in regulating gene expression, aiding in the understanding of cellular and organismal functional regulatory mechanisms. Furthermore, numerous studies have confirmed the existence of correlations between AA and other immune-related diseases. Examples include hyperthyroidism and rheumatoid arthritis. By understanding the interrelationships between AA and other immune diseases, we can further comprehend potential shared genetic foundations or pathogenic mechanisms among different diseases. Genetic research plays a crucial role in unraveling the pathogenesis of AA, as the identification of genetic variations associated with AA can assist in formulating more effective and targeted treatment strategies.

Aberrant inflammasome activation as a driving force of human autoimmune skin disease

Autoimmune skin diseases are understood as conditions in which the adaptive immune system with autoantigen-specific T cells and autoantibody-producing B cells reacting against self-tissues plays a crucial pathogenic role. However, there is increasing evidence that inflammasomes, which are large multiprotein complexes that were first described 20 years ago, contribute to autoimmune disease progression. The inflammasome and its contribution to the bioactivation of interleukins IL-1β and IL-18 play an essential role in combating foreign pathogens or tissue damage, but may also act as a pathogenic driver of myriad chronic inflammatory diseases when dysfunctionally regulated. Inflammasomes containing the NOD-like receptor family members NLRP1 and NLRP3 as well as the AIM2-like receptor family member AIM2 have been increasingly investigated in inflammatory skin conditions. In addition to autoinflammatory diseases, which are often associated with skin involvement, the aberrant activation of the inflammasome has also been implied in autoimmune diseases that can either affect the skin besides other organs such as systemic lupus erythematosus and systemic sclerosis or are isolated to the skin in humans. The latter include, among others, the T-cell mediated disorders vitiligo, alopecia areata, lichen planus and cutaneous lupus erythematosus as well as the autoantibody-driven blistering skin disease bullous pemphigoid. Some diseases are characterized by both autoinflammatory and autoimmune responses such as the chronic inflammatory skin disease psoriasis. Further insights into inflammasome dysregulation and associated pathways as well as their role in forming adaptive immune responses in human autoimmune skin pathology could potentially offer a new field of therapeutic options in the future.

Alopecia areata and tofacitinib: a prospective multicenter study from a Saudi population

BACKGROUND

Alopecia areata (AA) is an autoimmune disorder characterized by nonscarring hair loss that can involve the scalp, face, and body. Severe AA subtypes have a poorer prognosis and can be challenging to treat. Tofacitinib, a recently introduced Janus kinase inhibitor, has shown positive results in treating AA. This multicenter study demonstrates the efficacy of tofacitinib and the patient response rate in a Saudi population. It also highlights patient characteristics that may serve as predictors of the therapeutic response to tofacitinib.

METHODS

A prospective cohort study design was utilized. Study participants were included from three medical centers in Riyadh, Saudi Arabia. The Severity of Alopecia Tool (SALT) score was used to assess the percentage of hair loss at baseline and the percentage of hair regrowth at 3 and 6 months.

RESULTS

The sample size was 68 with an average baseline SALT score of 76.8 ± 27.6%. Data at 6 months were available for 45 patients. Of these, 62.2% achieved a SALT score of >50%. Patients with a score of <50% had a significantly higher baseline SALT score compared to patients with >50% score. The past use of systemic steroids was associated with a diminished response to therapy (P = 0.015). The response to therapy was significantly higher in patients with AA compared to alopecia totalis and alopecia universalis.

CONCLUSIONS

Tofacitinib is an effective and well-tolerated treatment for severe AA and exhibits a good safety profile.

NLRP3 inflammasome activation contributes to development of alopecia areata in C3H/HeJ mice

Alopecia areata (AA) is an autoimmune non‐scarring hair loss disease. Recently, several reports have suggested that innate immune systems such as interferon‐α (IFN‐α)‐producing plasmacytoid dendritic cells and NOD‐like receptor family pyrin domain‐containing protein 3 (NLRP3) inflammasomes play a role in the pathogenesis of AA. However, critical studies about their involvement in the initiation of AA have not yet been reported. Therefore, we investigated the expression of innate immune cytokines in serum and skin, and examined the effect of a selective NLRP3 inhibitor, MCC950, on AA in C3H/HeJ mice, induced by transferring cultured skin‐draining lymph node cells. IFN‐α production was upregulated in lesions of AA‐affected mice, and interleukin‐1β in serum and skin was highly expressed before onset as well as postonset. Furthermore, MCC950 treatment prevented AA development and promoted hair growth in AA mouse models by reducing NLRP3 signalling and Th1/Tc1 chemokines and cytokines in the skin. These results suggest that NLRP3 inflammasome contributes to AA onset and chronicity, and NLRP3 inhibitor may be a potential therapeutic agent for AA.

Cigarette Smoking, Alcohol Consumption, and Risk of Alopecia Areata: A Population-Based Cohort Study in Taiwan

BACKGROUND

The effects of cigarette smoking and alcohol consumption on the risk of alopecia areata (AA) are unclear.

OBJECTIVE

The aim was to examine the association of cigarette smoking and alcohol consumption with AA.

METHODS

We collected participants from four rounds (2001, 2005, 2009, and 2013) of the Taiwan National Health Interview Survey. Incident AA cases were identified from the National Health Insurance database.

RESULTS

Of the 60,055 participants, 154 developed AA during the 647,902 person-years of follow-up. After controlling for confounders, current smokers had a higher risk of incident AA than never smokers [adjusted hazard ratio (aHR) 1.88; 95% confidence interval (CI) 1.22-2.88]. There was a trend toward an increased risk of AA with increasing numbers of years of smoking and cumulative pack-years of smoking among current smokers. The aHRs (95% CIs) of current smokers of > 5 and ≤ 15 cigarettes per day, > 10 and ≤ 20 years of smoking, ≤ 10, and > 10 and ≤ 20 pack-years of smoking were 2.03 (1.17-3.51), 2.25 (1.21-4.18), 1.86 (1.12-3.09), and 2.04 (1.04-4.01), respectively. Conversely, social and regular drinkers had significantly lower risks of AA than never drinkers [aHRs (95% CIs) 0.65 (0.43-0.98) and 0.49 (0.26-0.93), respectively].

CONCLUSION

Current smokers had an increased risk of developing AA, while alcohol consumption was associated with a decreased risk of AA.

Alopecia areata: A multifactorial autoimmune condition

Alopecia areata is an autoimmune disease that results in non-scarring hair loss, and it is clinically characterised by small patches of baldness on the scalp and/or around the body. It can later progress to total loss of scalp hair (Alopecia totalis) and/or total loss of all body hair (Alopecia universalis). The rapid rate of hair loss and disfiguration caused by the condition causes anxiety on patients and increases the risks of developing psychological and psychiatric complications. Hair loss in alopecia areata is caused by lymphocytic infiltrations around the hair follicles and IFN-γ. IgG antibodies against the hair follicle cells are also found in alopecia areata sufferers. In addition, the disease coexists with other autoimmune disorders and can come secondary to infections or inflammation. However, despite the growing knowledge about alopecia areata, the aetiology and pathophysiology of disease are not well defined. In this review we discuss various genetic and environmental factors that cause autoimmunity and describe the immune mechanisms that lead to hair loss in alopecia areata patients.

Alopecia areata: a review of disease pathogenesis

BACKGROUND

Alopecia areata is a disorder that results in nonscarring hair loss. The psychological impact can be significant, leading to feelings of depression and social isolation. Objectives In this article, we seek to review the pathophysiological mechanisms proposed in recent years in a narrative fashion.

METHODS

We searched MEDLINE and Scopus for articles related to alopecia areata, with a particular emphasis on its pathogenesis.

RESULTS

The main theory of alopecia areata pathogenesis is that it is an autoimmune phenomenon resulting from a disruption in hair follicle immune privilege. What causes this breakdown is an issue of debate. Some believe that a stressed hair follicle environment triggers antigen presentation, while others blame a dysregulation in the central immune system entangling the follicles. Evidence for the latter theory is provided by animal studies, as well investigations around the AIRE gene. Different immune-cell lines including plasmacytoid dendritic cells, natural killer cells and T cells, along with key molecules such as interferon-γ, interleukin-15, MICA and NKG2D, have been identified as contributing to the autoimmune process.

CONCLUSIONS

Alopecia areata remains incurable, although it has been studied for years. Available treatment options at best are beneficial for milder cases, and the rate of relapse is high. Understanding the exact mechanisms of hair loss in alopecia areata is therefore of utmost importance to help identify potential therapeutic targets.

Genetic analysis of interleukin 18 gene polymorphisms in alopecia areata

BACKGROUND

Alopecia areata (AA), which appears as nonscarring hair shedding on any hair-bearing area, is a common organ-specific autoimmune condition. Cytokines have important roles in the development of AA. Interleukin (IL) 18 is a significant proinflammatory cytokine that was found higher in the patients with AA. We aimed to investigate whether the IL-18 (rs187238 and rs1946518) single nucleotide polymorphisms (SNPs) may be associated with AA and/or clinical outcome of patients with AA in Turkish population.

METHODS

Genotyping of rs187238 and rs1946518 SNPs were detected using sequence-specific primer-polymerase chain reaction (SSP-PCR) method in 200 patients with AA and 200 control subjects.

RESULTS

The genotype distribution of rs1946518 (-607C>A) SNP was found to be statistically significantly different among patients with AA and controls (P = .0008). Distribution of CC+CA genotypes and frequency of -607/allele C of rs1946518 SNP were higher in patients with AA (P = .001, P = .001, respectively). The genotype distribution of rs187238 (-137G>C) SNP was found to be statistically significantly different among patients with AA and control subjects (P = .0014). Distribution of GG genotype and frequency of -137/allele G of rs187238 SNP were higher in patients with AA (P = .0003, P = .001, respectively).

CONCLUSION

The rs1946518 (-607C>A) and rs187238 (-137G>C) polymorphisms were found associated with alopecia areata disease. The study suggests that IL-18 rs187238 and rs1946518 SNPs may be the cause of the AA susceptibility.

Erythroid Differentiation Regulator 1 as a Novel Biomarker for Hair Loss Disorders

Erythroid differentiation regulator 1 (Erdr1) is known to be involved in the inflammatory process via regulating the immune system in many cutaneous disorders, such as psoriasis and rosacea. However, the role of Erdr1 in various hair loss disorders remains unclear. The aim of this study was to investigate the putative role of Erdr1 in alopecias. Skin samples from 21 patients with hair loss disorders and five control subjects were retrieved, in order to assess their expression levels of Erdr1. Results revealed that expression of Erdr1 was significantly downregulated in the epidermis and hair follicles of patients with hair loss disorders, when compared to that in the control group. In particular, the expression of Erdr1 was significantly decreased in patients with alopecia areata. We propose that Erdr1 downregulation might be involved in the pathogenesis of hair loss, and could be considered as a novel biomarker for hair loss disorders.

Association study between growth hormone receptor (GHR ) gene polymorphisms and obesity in Korean population

A main target of growth hormone (GH) is adipose tissue in human body. The GH secretion in obesity patients is impaired. It is needless to say that growth hormone receptor (GHR) is necessary in GH hormone signaling. The purpose of the present study is to examine the association between single nucleotide polymorphisms (SNPs) and the development of obesity. A total of 211 overweight/obese subjects with a body mass index (BMI) ≥23 kg/m² and 157 nonoverweight/obese controls with a BMI of 18.5-23.0 kg/m² were involved in this study. Seven SNPs including the rs6451620 (intron), rs4130114 (intron), rs4410646 (intron), rs6898743 (intron), rs4394131 (intron), rs6182 (Cys440Phe), and rs6184 (Pro579Thr) and rs2229765 SNPs of GHR gene were genotyped. Genotyping was performed using custom DNA chip. SNPStats was used to calculate the odds ratio, 95% confidence interval, and P-value. The link-age disequilibrium block and haplotypes among seven SNPs were determined using Haploview version 4.2. Dominant, recessive, and log-additive genetic models were conducted for genetic analyzing. Among tested SNPs in GHR gene, rs4410646 and rs6898743 showed significant association with obesity (rs4410646, P=0.02 in dominant model and P=0.036 in log-additive model; rs6898743, P=0.039 in dominant model and P=0.044 in log-additive model). In summary, these results suggest that GHR gene polymorphisms might play a role in the development of obesity in the Korean population.

Association study between growth hormone receptor (GHR ) gene polymorphisms and obesity in Korean population

A main target of growth hormone (GH) is adipose tissue in human body. The GH secretion in obesity patients is impaired. It is needless to say that growth hormone receptor (GHR) is necessary in GH hormone signaling. The purpose of the present study is to examine the association between single nucleotide polymorphisms (SNPs) and the development of obesity. A total of 211 overweight/obese subjects with a body mass index (BMI) ≥23 kg/m² and 157 nonoverweight/obese controls with a BMI of 18.5–23.0 kg/m² were involved in this study. Seven SNPs including the rs6451620 (intron), rs4130114 (intron), rs4410646 (intron), rs6898743 (intron), rs4394131 (intron), rs6182 (Cys440Phe), and rs6184 (Pro579Thr) and rs2229765 SNPs of GHR gene were genotyped. Genotyping was performed using custom DNA chip. SNPStats was used to calculate the odds ratio, 95% confidence interval, and P-value. The link-age disequilibrium block and haplotypes among seven SNPs were determined using Haploview version 4.2. Dominant, recessive, and log-additive genetic models were conducted for genetic analyzing. Among tested SNPs in GHR gene, rs4410646 and rs6898743 showed significant association with obesity (rs4410646, P=0.02 in dominant model and P=0.036 in log-additive model; rs6898743, P=0.039 in dominant model and P=0.044 in log-additive model). In summary, these results suggest that GHR gene polymorphisms might play a role in the development of obesity in the Korean population.

IL-18 and Cutaneous Inflammatory Diseases

Interleukin (IL)-18, an IL-1 family cytokine, is a pleiotropic immune regulator. IL-18 plays a strong proinflammatory role by inducing interferon (IFN)-γ. Previous studies have implicated IL-18 in the pathogenesis of various diseases. However, it is not well understood biologic activities of IL-18 in the diverse skin diseases. Here, we have reviewed the expression and function of IL-18 in skin diseases including inflammatory diseases. This article provides an evidence-based understanding of the role of IL-18 in skin diseases and its relationship with disease activities.