Functional interrogation of lymphocyte subsets in alopecia areata using single-cell RNA sequencing.

Alopecia areata (AA) is among the most prevalent autoimmune diseases, but the development of innovative therapeutic strategies has lagged due to an incomplete understanding of the immunological underpinnings of disease. Here, we performed single-cell RNA sequencing (scRNAseq) of skin-infiltrating immune cells from the graft-induced C3H/HeJ mouse model of AA, coupled with antibody-based depletion to interrogate the functional role of specific cell types in AA in vivo. Since AA is predominantly T cell-mediated, we focused on dissecting lymphocyte function in AA. Both our scRNAseq and functional studies established CD8+ T cells as the primary disease-driving cell type in AA. Only the depletion of CD8+ T cells, but not CD4+ T cells, NK, B, or γδ T cells, was sufficient to prevent and reverse AA. Selective depletion of regulatory T cells (Treg) showed that Treg are protective against AA in C3H/HeJ mice, suggesting that failure of Treg-mediated immunosuppression is not a major disease mechanism in AA. Focused analyses of CD8+ T cells revealed five subsets, whose heterogeneity is defined by an "effectorness gradient" of interrelated transcriptional states that culminate in increased effector function and tissue residency. scRNAseq of human AA skin showed that CD8+ T cells in human AA follow a similar trajectory, underscoring that shared mechanisms drive disease in both murine and human AA. Our study represents a comprehensive, systematic interrogation of lymphocyte heterogeneity in AA and uncovers a novel framework for AA-associated CD8+ T cells with implications for the design of future therapeutics.

Identification of Potential Hub Genes in Alopecia Areata.

Alopecia areata (AA) is an immune-mediated chronic alopecia disease, but its specific pathogenesis is unclear. Gene expression data for AA patients (AAs) and healthy controls (HCs) were retrieved from the GEO database, and the differentially expressed genes (DEGs) between AAs and HCs were identified. Then, GO, KEGG and GSEA analysis were performed. A PPI network for the DEGs was then constructed to screen for hub genes, which were validated by three additional datasets. Subsequently, the potential miRNAs interacting with the hub genes were obtained through TarBase and miRNet. The differentially expressed lncRNAs (DElncRs) were obtained for subcellular localisation analysis, and the DElncRs located in the cytoplasm were further screened to identify miRNAs that interact with them. The shared miRNAs interacting with the hub genes and lncRNAs were used to construct a network of mRNA-miRNA-lncRNA interactions. Lastly, ROC analysis was performed to evaluate the potential diagnostic value of the hub genes and DElncRs identified. A total of 173 DEGs were obtained, mainly enriched in cytokines, chemokines, hair follicle development and hair cycle related signalling pathways. Through PPI screening and validation based on 3 additional datasets, 24 hub genes were finally yielded. Of them, five hub genes were upregulated and the potential miRNAs that interact with these five hub genes were identified. Additionally, 26 DElncRs were obtained, including 9 upregulated lncRNAs located in the cytoplasm that were predicted to interact with the miRNAs. Finally, an mRNA-miRNA-lncRNA regulatory network was constructed using five hub genes, four lncRNAs and their shared five miRNAs. The regulatory relationship between CD8A, mir-185-5p and FOXD2-AS1 might be crucial in AA pathogenesis, with CD8A and FOXD2-AS1 exhibiting diagnostic potential. CD8A and FOXD2-AS1 may serve as potential therapeutic targets in AA.

Serum lipids may causally affect the occurrence of alopecia areata: A Mendelian randomization study.

PURPOSE: The etiology of alopecia areata (AA) in relation to serum lipids remains unclear, thereby prompting our intention to do Mendelian study on this subject. DESIGN: Two-sample Mendelian randomization (MR) analysis was performed in the study. The inverse variance-weighted method was used as the primary method. METHODS: In our study, we integrated a set of 123 single-nucleotide polymorphisms (SNPs) into our analysis. These SNPs have been extensively studied and are known to exhibit associations with serum lipids. We sourced these SNPs from a variety of relevant studies and consortia that specifically focus on lipid-related research, such as the MRC Integrative Epidemiology Unit. These carefully curated SNPs were then utilized as instrumental variables in our analysis, allowing us to explore and evaluate the causal relationships between these genetic variants and serum lipids. By incorporating this comprehensive set of SNPs, we aimed to enhance the precision and robustness of our findings, shedding light on the intricate interplay between genetics and serum lipids. RESULTS: In the MR analysis, a higher total lipid concentration in large low-density lipoprotein (LDL) particles (odds ratio [OR] = 1.502; 95% confidence interval [CI] = 1.086-1.953; p = 0.006), a greater ratio of cholesteryl esters to total lipids in chylomicrons and extremely large very LDL (VLDL) particles (OR = 2.174; 95% CI = 1.300-2.500; p = 0.010), and a greater ratio of cholesterol to total lipids in chylomicrons and extremely large VLDL particles (OR = 2.363;95% CI = 1.556-4.438; p = 0.004), were genetically predicted to be causally associated with an increased risk of AA, while patients with a higher triglyceride to total lipids ratio in chylomicrons and extremely large VLDL particles had a lower risk of AA (OR = 0.481; 95% CI = 0.191-1.270; p = 0.002). CONCLUSION: This study found that serum lipids may be causally implicated in AA.

Explore the genetic exposure to alopecia areata.

BACKGROUND: Alopecia areata is an autoimmune hair loss disorder with an incompletely understood etiology. Although trace elements, serum metabolites, and inflammatory factors are implicated in the disease, the potential causal relationships between these factors and alopecia areata require further investigation. METHODS: This study employed Mendelian randomization (MR), utilizing data from genome-wide association studies, to explore the causal relationships between 15 trace elements, 1400 serum metabolites, and 91 inflammatory factors and alopecia areata. The analysis was conducted using the inverse variance weighted (IVW) method complemented by various sensitivity analyses, including Cochran's Q test, MR-Egger regression intercept test, MR-PRESSO global test, and leave-one-out analysis, to assess the robustness of the results. RESULTS: MR analysis indicated a negative correlation between copper levels and the risk of developing alopecia areata (odds ratio = 0.86, 95% confidence interval: 0.75-0.99, p = 0.041). Additionally, causal relationships were identified between 15 serum metabolites and 6 inflammatory factors and the risk of alopecia areata (IVW, all p values < 0.05). CONCLUSION: This study provides genetic evidence of the relationships between trace elements, serum metabolites, and alopecia areata, underscoring the potential value of targeted therapeutic strategies and preventive measures. Future research should expand to diverse populations and further explore the specific roles of these biomarkers in the disease mechanism.

Gut microbiota, skin microbiota, and alopecia areata: A Mendelian randomization study.

BACKGROUND: Observational studies have shown an association between skin microbiota and alopecia areata (AA), but the causal connection remains ambiguous. METHODS: We obtained data on skin microbiota and AA from summary statistics of Genome-Wide Association Studies and applied statistical methods from Mendelian randomization (MR) to assess causal relationships. Additionally, we investigated whether the skin microbiota acts as a mediator in the pathway from gut microbiota to AA. RESULTS: In the MR analysis of KORA FF4 and AA, the inverse-variance weighting method indicated that Corynebacterium (odds ratio [OR] = 0.82, 95% confidence interval [CI]: 0.70-0.96, p = 0.02) and asv037 (OR = 0.87, 95% CI: 0.76-0.99, p = 0.05) exerted protective effects, while Betaproteobacteria (OR = 1.21, 95% CI: 1.01-1.44, p = 0.03), asv015 (OR = 1.27, 95% CI: 1.05-1.54, p = 0.02), and Burkholderiales (OR = 1.20, 95% CI: 1.04-1.38, p = 0.01) were identified as risk factors in AA. In the MR analysis of PopGen and AA, asv001 (OR = 1.12, 95% CI: 1.01-1.24, p = 0.04), asv054 (OR = 1.13, 95% CI: 1.01-1.25, p = 0.03), and asv059 (OR = 1.14, 95% CI: 1.02-1.27, p = 0.02) were found to potentially increase the risk in AA. Furthermore, in the influence of gut microbiota on AA, the skin microbiota did not act as a mediator. CONCLUSION: Our analysis suggests potential causal relationships between certain skin microbiota and AA, revealing insights into its pathogenesis and potential intervention strategies.

Genetic association between asthma and alopecia areata: A two-sample Mendelian randomization study.

BACKGROUND: Many patients with asthma experience alopecia areata (AA) in their lives. However, it is unclear whether asthma causes or results from AA. Our objective was to investigate the genetic causal relationship between asthma and AA. METHODS: Two-sample Mendelian randomization (MR) was used to assess the causal relationship between asthma and AA based on the largest publicly available genome-wide association study summary statistics. Androgenetic alopecia (AGA) and cicatricial alopecia (CA) were chosen as the control groups for AA. The main estimates were obtained using inverse variance weighting meta-analysis (IVW), Mendelian randomization-Egger (MR-Egger), maximum likelihood estimation, and the weighted median. Sensitivity analyses were conducted using Cochran's Q test, MR-Egger, and leave-one-out methods. Lastly, we conducted a reverse MR analysis to evaluate the possibility of reverse causation. RESULTS: Genetically, asthma is associated with an increased risk of AA, while the association between genetically predicted AGA or CA and asthma was negative. The risk of AA increased by 1.86 times in patients with asthma under the IVW method (OR = 1.86, 95% CI = 1.31-2.629, p < 0.001). The reverse MR analysis did not find evidence supporting reverse causality from three phenotypes of alopecia to asthma. Sensitivity analyses yielded consistent causal estimates. CONCLUSION: This study suggests that asthma is causally associated with AA. The findings deepen our understanding of the role of asthma in the pathology of AA, which emphasizes the potential for opening a new vista for the prevention and diagnosis of AA.

Thyroid Dysfunction and Alopecia Areata: A Genetic Prediction Causality Analysis Study.

BACKGROUND: Observational studies have suggested a correlation between alopecia areata (AA) and thyroid dysfunction (TD). However, the causal relationship between AA and TD remains uncertain. The purpose of this study is to investigate the causal relationship between these two conditions. Understanding the potential causal relationship between AA and TD is valuable for elucidating the pathogenesis of AA and for designing innovative methods to prevent and treat AA and its related complications. METHODS: All data for this two-sample Mendelian randomization (MR) study were sourced from public databases. This study selected hypothyroidism, Hashimoto's thyroiditis, hyperthyroidism, subacute thyroiditis, and Graves' disease as exposure factors, with AA as the outcome variable. Data for hypothyroidism, Hashimoto's thyroiditis, hyperthyroidism, subacute thyroiditis, Graves' disease, and AA were obtained from related genome-wide association studies (GWAS). Various MR analysis methods such as inverse variance weighted (IVW), MR-Egger, and weighted median were utilized. Additionally, Cochrane's Q test was used to detect heterogeneity in MR results, and the MR-Egger intercept test and MR pleiotropy residual sum and outlier (MR-PRESSO) test were used to detect horizontal pleiotropy. A leave-one-out analysis was conducted to investigate the sensitivity of this association. RESULTS: We found statistically significant genetic predictions of AA with hypothyroidism, Hashimoto's thyroiditis, and subacute thyroiditis (IVW OR = 1.4009815, 95% confidence interval [CI]: 1.1210399-1.750829; p = 0.003030698, OR = 1.396101, 95% CI: 1.030134-1.89208; p = 0.03144273, OR = 0.732702, 95% CI: 0.604812-0.887634; p = 0.001483368). Furthermore, tests for pleiotropy showed no evidence of pleiotropy, enhancing the credibility of the study results. Finally, the leave-one-out test demonstrated the stability and robustness of this association. CONCLUSION: This study provides new evidence of a potential genetic link between thyroid issues and AA. By employing the two-sample MR method to eliminate confounding factors and reverse causation, unbiased results were obtained, confirming a causal relationship between hypothyroidism, Hashimoto's thyroiditis, subacute thyroiditis, and AA. This lays the foundation for further mechanistic studies and potential clinical applications. Future research should further explore the specific biological mechanisms between TD and the onset of AA.

C-reactive protein as a novel biomarker for vitamin D deficiency in alopecia areata.

BACKGROUND: Alopecia areata (AA) is an autoimmune condition characterized by sudden and unpredictable hair loss, with a lifetime incidence of 2%. AA can be divided into three categories: patchy alopecia, alopecia totalis, and alopecia universalis. It can affect a person's psychological health and overall quality of life. Elevated C-reactive protein (CRP) levels in the liver may indicate an inflammatory response in autoimmune diseases. Vitamin D, essential for immune system control and skin health, may be related to AA. Hair follicles contain vitamin D receptors, which control immunological responses in the skin. However, no study has found a relationship between CRP and vitamin D in AA patients in our region. SUBJECTS AND METHODS: An analytical cross-sectional study with a case-control design research investigation of 82 AA patients and 81 healthy controls was carried out. Both groups' medical histories were taken. Biochemical analysis was done for both groups as well as the serum vitamin D levels, and CRP. Genetic analysis for CDX2 rs11568820 variant detected by PCR (T-ARMS-PCR) method and vitamin D receptor (VDR) gene expression measured by real-time PCR analysis for both patients and healthy subjects. RESULTS: CRP levels are higher in AA patients, AA patients with G/G genotypes exhibited higher concentrations of CRP when compared to those with A/A and A/G genotypes while patients with A/A genotypes have higher levels of Serum vitamin D as compared to the A/G and G/G genotypes. G allele was more abundant in AA patients. VDR gene expression was lower in AA compared to control and lower in ophiasis compared to localized and multiple patchy AA. An important inverse linear correlation was observed between vitamin D and CRP levels in ophiasis AA. CONCLUSION: CRP concentrations were found to be elevated in AA patients. The considerable accuracy of CRP in the diagnosis of AA is substantiated by a statistically significant al. A noteworthy inverse linear association was observed between serum vitamin D and CRP concentrations in ophiasis AA.

The role of hsa-miR-193a-5p as an important factor for control of inositol in alopecia areata.

BACKGROUND: MicroRNAs (miRNAs) are small RNA molecules that play a regulatory role in various biological processes by acting as intracellular mediators. They hold great potential as therapeutic agents for targeting human disease pathways; however, there is still much to be uncovered about their mechanism of gene regulation. Alopecia areata (AA) is a commonly occurring inflammatory condition characterized by the infiltration of T cells that specifically target the anagen-stage hair follicle. The limited understanding of its precise cellular mechanism may be the reason behind the scarcity of effective treatments for AA. AIM: The significance and function of hsa-miR-193a-5p as a genetic marker for AA and its potential influence on the advancement of the disease. SUBJECTS AND METHODS: A case-control study comprised 77 individuals diagnosed with AA who were matched with 75 healthy controls. In order to measure the expression of miR-200c-3p in both groups, the real-time PCR technique was utilized. The prediction of suitable genes for hsa-miR-193a-5p, as well as the identification of pathways and gene-gene interactions, were carried out using bioinformatic tools. RESULTS: The levels of hsa-miR-193a-5p expression were notably elevated in AA patients in comparison to healthy controls. Our prediction suggests that the involvement of hsa-miR-193a-5p in the development of AA is significant due to its influence on the inositol phosphorylation pathway and the Phosphatidylinositol signaling system, achieved through its direct impact on the IPPK gene. CONCLUSION: For the first time, our study demonstrates the significant over-expression of a new miRNA, hsa-miR-193a-5p, in the blood of AA patients compared to controls, and highlights its impact on the IPPK gene and the inositol phosphorylation and Phosphatidylinositol signaling pathways, suggesting a potential therapeutic role for hsa-miR-193a-5p in AA.

Co-regulatory mechanisms and potential markers of oxidative stress-related genes in vitiligo and alopecia areata.

BACKGROUND: The specific role of oxidative stress (OS) in vitiligo and alopecia areata (AA) remains unclear. The aim of this study was to analyze and identify the key markers of OS in vitiligo and AA by bioinformatics. METHODS: We obtained vitiligo and AA datasets from gene expression omnibus (GEO) database. The difference-expressed genes of vitiligo and AA were identified by differential analysis, and the functions of difference-expressed genes were identified by gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) enrichment analysis. Subsequently, Veen package was used to obtain the intersection genes of OS-related genes with vitiligo and AA. Finally, we used CIBERSORT to assess the infiltration of immune cells in vitiligo and AA. RESULTS: Through enrichment analysis, we found that vitiligo and AA were mainly enriched in cell cycle and cell adhesion molecular channels. We identified KLB and EIF3C as key genes in OS regulation of vitiligo and AA, and found that KLB and EIF3C participate in disease progression by regulating T cells and neutrophils. CONCLUSIONS: According to our findings, KLB and EIF3C play a crucial role in the progression and development of vitiligo and AA, which have been identified as biomarkers and target for early diagnosis of patients.

MiR-200c-3p as a novel genetic marker and therapeutic tool for alopecia areata.

BACKGROUND: MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression in diverse biological processes. They hold promise as therapeutic candidates for targeting human disease pathways, although our understanding of their gene regulatory mechanism remains incomplete. Alopecia areata (AA) is a prevalent inflammatory ailment distinguished by the infiltration of T cells targeting the anagen-stage hair follicles. The scarcity of effective remedies for AA may stem from limited understanding regarding its precise cellular mechanism. AIM: To investigate and examine the importance and role of the miR-200c-3p as a genetic indicator for AA, and its possible impact on disease progression. SUBJECTS AND METHODS: Case-control study included 65 patients with AA and 65 matched healthy controls. A real-time PCR technique was used to measure the expression of miR-200c-3p for both groups. Bioinformatic tools were used for prediction with genes and gene-gene interaction, and protein-protein interaction. RESULTS: The expression levels of miR-200c-3p were significantly higher in AA patients than in healthy controls. We predicted that miR-200c-3p plays a markable role in the development of AA by its effect on the EGFR tyrosine kinase inhibitor resistance pathway. CONCLUSION: We were able to identify the influence of miR-200c-3p on both PLCG1 and RPS6KP1 genes which in turn regulate the EGFR tyrosine kinases resistance pathway that displayed the most substantial increase in activity. Our outcomes shed light on the era of the potential theranostic role of this innovative miRNA in AA.

Interleukin-33 links asthma to alopecia areata: Mendelian randomization and mediation analysis.

OBJECTIVE: The objective of this study is to elucidate the causal association between asthma and alopecia areata (AA) through the application of Mendelian randomization (MR) analysis, leveraging summary data from genome-wide association studies (GWAS). Additionally, it explores potential mediating factors. MATERIALS AND METHODS: Mendelian randomization (MR) analysis was employed to investigate the causal relationship between asthma and AA using genetic instrumental variables (IVs) for asthma, 91 circulating inflammatory proteins, and AA extracted from large-scale GWAS. The primary analytical approach utilized the inverse-variance weighted (IVW) method, supplemented by weighted median and MR-Egger methods to assess robustness. Tests for heterogeneity and pleiotropy were conducted to ensure result reliability. Furthermore, the study examined the mediating role of circulating inflammatory proteins in the asthma-AA relationship. RESULTS: The findings revealed an increased risk of AA among asthma patients (odds ratio (OR) = 14.070; 95% confidence interval (CI) = 1.410-140.435; P = 0.024). Interleukin-33 (IL-33) emerged as a significant mediator in the asthma-AA relationship, explaining 13.1% of the mediation effect. Bidirectional Mendelian randomization analyses did not establish a causal effect of AA on asthma occurrence. CONCLUSION: This study, utilizing Mendelian Randomization, elucidates the causal link between asthma and AA, highlighting the mediating role of IL-33. These findings underscore the importance of considering AA risk in asthma management and offer insights for potential therapeutic strategies targeting IL-33. Future research should explore additional biomarkers and mediating mechanisms between asthma and AA to enhance treatment approaches and patient quality of life.

Association analysis of the IKZF4 gene with Alopecia Areata in the Chinese Han population.

Objective: The IKZF4(Ikaros family zinc finger 4) gene encodes Eos, a zinc finger transcription factor that belongs to the Ikaros family. High expression of Eos on Treg cells is important for the suppression of autoimmune responses and immune homeostasis. It has been suggested that the SNP in IKZF4 may influence the pathogenesis of AA(alopecia areata). The purpose of this study was to explore the relationship between IKZF4 polymorphism and AA in the Chinese Han population. Methods: We examined 459 patients and 434 controls in this study. The rs1701704 polymorphism was evaluated using HRM analysis and direct sequencing. Results: The prevalence of the C/C, A/C, and A/A genotypes in AA patients was 7.4%, 37.5% and 55.1%, respectively. There were significant differences in genotype distribution and allele frequencies between AA and the control group (P < .0001). The frequency of the C allele in the AA group was significantly higher (P < .0001), and the frequencies of the C allele and C/C genotype in patients with family history were higher (P < .0001; P = .001). Conclusions: The rs1701704 SNP of IKZF4 may be a genetic marker for assessing the risk of AA in the Chinese Han population.

Deciphering the Complex Immunopathogenesis of Alopecia Areata.

Alopecia areata (AA) is an autoimmune-mediated disorder in which the proximal hair follicle (HF) attack results in non-scarring partial to total scalp or body hair loss. Despite the growing knowledge about AA, its exact cause still needs to be understood. However, immunity and genetic factors are affirmed to be critical in AA development. While the genome-wide association studies proved the innate and acquired immunity involvement, AA mouse models implicated the IFN-γ- and cytotoxic CD8+ T-cell-mediated immune response as the main drivers of disease pathogenesis. The AA hair loss is caused by T-cell-mediated inflammation in the HF area, disturbing its function and disrupting the hair growth cycle without destroying the follicle. Thus, the loss of HF immune privilege, autoimmune HF destruction mediated by cytotoxic mechanisms, and the upregulation of inflammatory pathways play a crucial role. AA is associated with concurrent systemic and autoimmune disorders such as atopic dermatitis, vitiligo, psoriasis, and thyroiditis. Likewise, the patient's quality of life (QoL) is significantly impaired by morphologic disfigurement caused by the illness. The patients experience a negative impact on psychological well-being and self-esteem and may be more likely to suffer from psychiatric comorbidities. This manuscript aims to present the latest knowledge on the pathogenesis of AA, which involves genetic, epigenetic, immunological, and environmental factors, with a particular emphasis on immunopathogenesis.

Genetic Polymorphisms of Immunity Regulatory Genes and Alopecia Areata Susceptibility in Jordanian Patients.

Background and Objectives: Alopecia areata (AA) is a tissue-specific immune-mediated disorder that affects hair follicles and the nail apparatus. Due to the collapse of hair follicle immune privilege in AA, hair loss ranges in severity from small, localized patches on the scalp to the loss of entire body hair. Although AA is of uncertain etiology, the disease has a common genetic basis with a number of other autoimmune diseases. Materials and Methods: To identify candidate genes that confer susceptibility to AA in the Jordanian population and further understand the disease background, we performed DNA genotyping using case-control samples of 152 patients and 150 healthy subjects. Results: While no significant result was observed in the ten single-nucleotide polymorphisms (SNPs), CLEC4D rs4304840 variants showed significant associations with AA development within our cohort (p = 0.02). The strongest associations were for the codominant and recessive forms of rs4304840 (p = 0.023 and p = 0.0061, respectively). Conclusions: These findings suggest that CLEC4D gene variants may contribute to AA pathogenesis among Jordanians. Further advanced genetic analysis and functional investigations are required to elucidate the genetic basis of the disease.

Mitochondrial DNA copy number as a diagnostic marker and indicator of degree of severity in alopecia areata.

Alopecia areata (AA) is a disorder with several etiologies. The evidence suggests that the absolute copy number of mitochondrial deoxyribonucleic acid (mtDNA), as well as proportion of mutated mtDNA copies, determines disease onset. This study aims to quantify the relative index of the mtDNA copy number in patients with AA and healthy controls and correlate the results with the existing clinical information. This case-control study included 50 patients with AA and 50 age- and sex-coordinated healthy persons as controls. The severity of AA was weighed using the Severity of Alopecia Tool and Kavak's classification. The relative index of the mtDNA copy number was measured by real-time qPCR. Significant statistical difference was observed between cases and controls regarding mean mtDNA copy number, p < .001. There was significant positive correlation with SALT score (p = â€…0.001). A cutoff value of >1.619 N/µL could significantly diagnose AA cases (p < .001), and a cutoff value of > 1.36 N/µL could discriminate mild AA cases from those with moderate AA (p = â€…0.007). The relative index of mtDNA copy number is significantly elevated in AA cases and could be helpful in diagnosing and evaluating AA severity.

Stratification of alopecia areata reveals involvement of CD4 T cell populations and altered faecal microbiota.

Alopecia areata (AA) is an immune-mediated disease that causes non-scarring hair loss. Autoreactive CD8 T cells are key pathogenic effectors in the skin, and AA has been associated both with atopy and with perturbations in intestinal homeostasis. This study aimed to investigate mechanisms driving AA by characterizing the circulating immunophenotype and faecal microbiome, and by stratifying AA to understand how identified signatures associated with heterogeneous clinical features of the condition. Flow cytometric analyses identified alterations in circulating B cells and CD4 T cells, while 16S sequencing identified changes in alpha and beta diversity in the faecal microbiome in AA. The proportions of transitional and naïve B cells were found to be elevated in AA, particularly in AA samples from individuals with >50% hair loss and those with comorbid atopy, which is commonly associated with extensive hair loss. Although significant changes in circulating CD8 T cells were not observed, we found significant changes in CD4+ populations. In individuals with <50% hair loss higher frequencies of CCR6+CD4 ("Th17") and CCR6+CXCR3+CD4 ("Th1/17") T cells were found. While microbial species richness was not altered, AA was associated with reduced evenness and Shannon diversity of the intestinal microbiota, again particularly in those with <50% hair loss. We have identified novel immunological and microbial signatures in individuals with alopecia areata. Surprisingly, these are associated with lower levels of hair loss, and may therefore provide a rationale for improved targeting of molecular therapeutics.

Association of CTLA-4 gene polymorphisms and alopecia areata: a systematic review and meta-analysis.

OBJECTIVE: To provide evidence of the association between CLTA-4 gene polymorphisms and alopecia areata (AA). METHODS: PubMed, EMBASE, Web of Science, Cochrane, Wanfang, and CNKI databases were searched until 30 April 2021. The selection was completed according to the inclusion and exclusion criteria. The study quality assessment was based on Newcastle-Ottawa Scale. The assessment of the association was measured by ORs and 95%CIs. RESULTS: Nine studies, containing 2858 AA cases and 5444 disease-free control subjects were included. For rs231775 polymorphism, no significant association with AA was found, which was A vs. a, OR = 1.02 [0.81, 1.30], p = 0.85; AA vs. aa, OR = 1.26 [0.81, 1.97], p = 0.31; Aa vs. aa, OR = 1.04 [0.54, 2.01], p = 0.91; AA + Aa vs. aa, OR = 1.04 [0.71, 1.53], p = 0.82; AA vs. Aa + aa, OR = 1.31 [0.97, 1.78], p = 0.08. For rs3087243 polymorphism, also no significant association was found, which was A vs. a, OR = 0.93 [0.78, 1.11]; p = 0.40, AA vs. aa, OR = 0.68 [0.44, 1.06]; p = 0.09; Aa vs. aa, OR = 0.87 [0.45, 1.68], p = 0.68; AA + Aa vs. aa, OR = 0.93 [0.68, 1.28], p = 0.66; AA vs. Aa + aa, OR = 0.78 [0.34, 1.81], p = 0.57. For rs231726 polymorphism, a significant correlation was found, which was A vs. a, OR = 0.76 [0.70, 0.82], p < 0.05. CONCLUSIONS: A significant correlation between CTLA-4 rs231726 polymorphism and AA susceptibility was found, but no significant association of CTLA-4 gene rs231775 and rs3087243 polymorphisms and AA susceptibility was found.

Prediction of the Risk of Alopecia Areata Progressing to Alopecia Totalis and Alopecia Universalis: Biomarker Development with Bioinformatics Analysis and Machine Learning.

BACKGROUND: Alopecia areata (AA) is an autoimmune disease typified by nonscarring hair loss with a variable clinical course. Although there is an increased understanding of AA pathogenesis and progress in its treatments, the outcome of AA patients remains unfavorable, especially when they are progressing to the subtypes of alopecia totalis (AT) or alopecia universalis (AU). Thus, identifying biomarkers that reflect the risk of AA progressing to AT or AU could lead to better interventions for AA patients. METHODS: In this study, we conducted bioinformatics analyses to select key genes that correlated to AU or AT based on the whole-genome gene expression of 122 human scalp skin biopsy specimens obtained from NCBI-GEO GSE68801. Then, we built a biomarker using 8 different machine learning (ML) algorithms based on the key genes selected by bioinformatics analyses. RESULTS: We identified 4 key genes that significantly increased (CD28) or decreased (HOXC13, KRTAP1-3, and GPRC5D) in AA tissues, especially in the subtypes of AT and AU. Besides, the predictive accuracy (area under the curve [AUC] value) of the prediction models for forecasting AA patients progressing to AT/AU models reached 90.7% (87.9%) by logistic regression, 93.8% (79.9%) by classification trees, 100.0% (76.3%) by random forest, 96.9% (76.3%) by support vector machine, 83.5% (79.9%) by K-nearest neighbors, 97.1% (87.3%) by XGBoost, and 93.3% (80.6%) by neural network algorithms for the training (internal validation) cohort. Besides, 2 molecule drugs, azacitidine and anisomycin, were identified by Cmap database. They might have the potential therapeutic effects on AA patients with high risk of progressing to AT/AU. CONCLUSIONS: In the present study, we conducted high accuracy models for predicting the risk of AA patients progressing to AT or AU, which may be important in facilitating personalized therapeutic strategies and clinical management for different AA patients.

Is heritability of alopecia areata sex-specific? A nationwide population-based cohort study.

Previous studies have demonstrated the heritability of alopecia areata (AA). However, whether the heritability of AA is sex-specific has not been examined. A nationwide population-based retrospective cohort study was performed using the Taiwan Maternal and Child Health Database from 2004 to 2017. We examined the heritability of AA in offspring of parents with and without AA, and determined whether the transmission of AA from parents to the next generation may occur in opposite directions depending on sex. We found that the risk ratio (RR) for heritability of AA between parents with and without AA was approximately two-fold. In addition, for fathers with AA, the risk of AA in offspring tended to be higher in girls than in boys (RR: 2.97; 95% confidence interval: 0.94, 9.31). Therefore, the present study confirms the heritability of AA, and further studies examining the sex-specific heritability of AA with a larger sample are warranted.