Correlation between the genetic polymorphism of ORMDL3 gene and asthma risk: a meta-analysis

17q21 Variants Disturb Mucosal Host Defense in Childhood Asthma

Rationale: The strongest genetic risk factor for childhood-onset asthma, the 17q21 locus, is associated with increased viral susceptibility and disease-promoting processes.Objectives: To identify biological targets underlying the escalated viral susceptibility associated with the clinical phenotype mediated by the 17q21 locus.Methods: Genome-wide transcriptome analysis of nasal brush samples from 261 children (78 healthy, 79 with wheezing at preschool age, 104 asthmatic) within the ALLIANCE (All-Age-Asthma) cohort, with a median age of 10.0 (range, 1.0-20.0) years, was conducted to explore the impact of their 17q21 genotype (SNP rs72163891). Concurrently, nasal secretions from the same patients and visits were collected, and high-sensitivity mesoscale technology was employed to measure IFN protein levels.Measurements and Main Results: This study revealed that the 17q21 risk allele induces a genotype- and asthma/wheeze phenotype-dependent enhancement of mucosal GSDMB expression as the only relevant 17q21-encoded gene in children with preschool wheeze. Increased GSDMB expression correlated with the activation of a type-1 proinflammatory, cell-lytic immune, and natural killer signature, encompassing key genes linked to an IFN type-2-signature (IFNG, CXCL9, CXCL10, KLRC1, CD8A, GZMA). Conversely, there was a reduction in IFN type 1 and type 3 expression signatures at the mRNA and protein levels.Conclusions: This study demonstrates a novel disease-driving mechanism induced by the 17q21 risk allele. Increased mucosal GSDMB expression is associated with a cell-lytic immune response coupled with compromised airway immunocompetence. These findings suggest that GSDMB-related airway cell death and perturbations in the mucosal IFN signature account for the increased vulnerability of 17q21 risk allele carriers to respiratory viral infections during early life, opening new options for future biological interventions.The All-Age-Asthma (ALLIANCE) cohort is registered at www.clinicaltrials.gov (pediatric arm, NCT02496468).

Increased expression of ORMDL3 in allergic asthma: a case control and in vitro study

BACKGROUND

Asthma is the most frequent chronic disease in children. One of the most replicated genetic findings in childhood asthma is the ORMDL3 gene confirmed in several GWA studies in several pediatric populations.

OBJECTIVES

The purpose of this study was to analyze ORMDL3 variants and expression in childhood asthma in the Polish population.

METHODS

In the study we included 416 subject, 223 asthmatic children and 193 healthy control subjects. The analysis of two SNPs (rs3744246 and rs8076131) was performed using genotyping with TaqMan probes. The methylation of the ORMDL3 promoter was examined with Methylation Sensitive HRM (MS-HRM), covering 9 CpG sites. The expression of ORMDL3 was analyzed in PBMCs from pediatric patients diagnosed with allergic asthma and primary human bronchial epithelial cells derived from healthy subjects treated with IL-13, IL-4, or co-treatment with both cytokines to model allergic airway inflammation.

RESULTS

We found that ORMDL3 expression was increased in allergic asthma both in PBMCs from asthmatic patients as well as in human bronchial epithelial cells stimulated with the current cytokines. We did not observe significant differences between cases and controls either in the genotype distribution of analyzed SNPs (rs3744246 and rs8076131) nor in the level of promoter methylation.

CONCLUSIONS

Increased ORMDL3 expression is associated with pediatric allergic asthma and upregulated in the airways upon Th2-cytokines stimulation, but further functional studies are required to fully understand its role in this disease.

ORMDL3 overexpression facilitates FcεRI-mediated transcription of proinflammatory cytokines and thapsigargin-mediated PERK phosphorylation in RBL-2H3 cells

Introduction

The chromosomal region 17q21 harbors the human orosomucoid‐like 3 (ORMDL3) gene and has been linked to asthma and other inflammatory diseases. ORMDL3 is involved in the unfolded protein response (UPR), lipid metabolism, and inflammatory reactions. We investigated the effects of ORMDL3 overexpression in RBL‐2H3 cells to determine the contribution of ORMDL3 to inflammatory disease development.

Methods

We generated ORMDL3 stably overexpressing RBL‐2H3 cells to assess degranulation, transcriptional upregulation of interleukin‐4 (IL‐4), tumor necrosis factor‐α (TNF‐α), monocyte chemoattractant protein‐1 (MCP‐1), and mitogen‐activated protein kinase (MAPK) phosphorylation via FcεRI. In addition, we examined the effects of ORMDL3 overexpression on thapsigargin (TG)‐mediated proinflammatory cytokine transcription and UPR by monitoring MAPK, protein kinase‐like endoplasmic reticulum kinase (PERK), and inositol‐requiring enzyme 1 (IRE1) phosphorylation.

Results

Overexpression of ORMDL3 enhanced IL‐4, TNF‐α, and MCP‐1 expression after FcεRI cross‐linking, whereas the sphingosine‐1‐phosphate (S1P) agonist FTY720 suppressed this enhancement. There was no significant difference in degranulation and MAPK phosphorylation via FcεRI‐mediated activation between vector‐transfected and ORMDL3‐overexpressing cells. ORMDL3 overexpression accelerated TG‐mediated PERK phosphorylation, while MAPK phosphorylation and proinflammatory cytokine expression showed no significant changes in ORMDL3‐overexpressing cells.

Conclusions

Our findings suggest that ORMDL3 plays an important role in regulating proinflammatory cytokine expression via the S1P pathway and selectively affects the UPR pathway in mast cells.

Mechanisms Targeting the Unfolded Protein Response in Asthma

Lung cells are constantly exposed to various internal and external stressors that disrupt protein homeostasis. To cope with these stimuli, cells evoke a highly conserved adaptive mechanism called the unfolded protein response (UPR). UPR stressors can impose greater protein secretory demands on the endoplasmic reticulum (ER), resulting in the development, differentiation, and survival of these cell types to meet these increasing functional needs. Dysregulation of the UPR leads to the development of the disease. The UPR and ER stress are involved in several human conditions, such as chronic inflammation, neurodegeneration, metabolic syndrome, and cancer. Furthermore, potent and specific compounds that target the UPR pathway are under development as future therapies. The focus of this review is to thoroughly describe the effects of both internal and external stressors on the ER in asthma. Furthermore, we discuss how the UPR signaling pathway is activated in the lungs to overcome cellular damage. We also present an overview of the pathogenic mechanisms, with a brief focus on potential strategies for pharmacological interventions.

Asthma and obesity in the Middle East region: An overview

This paper aims to cover the current status of asthma and obesity in the Middle East, as well as to introduce the various studies tying the two diseases; further expanding on the proposed mechanisms. Finally, the paper covers recent literature related to sphingolipids and its role in asthma, followed by recommendations and future directions. In preparation of this paper, we searched PubMed and Google Scholar, with no restrictions, using the following terms; asthma, obesity, Middle East, sphingolipids. We also used the reference list of retrieved articles to further expand on the pool of articles that were used for this review.

Elevated fractional exhaled nitric oxide and blood eosinophil counts are associated with a 17q21 asthma risk allele in adult subjects

Background and objectives

Genome-wide association studies identified single-nucleotide polymorphisms (SNPs) at the 17q21 locus conferring increased risk for childhood-onset asthma. Little is known about how these SNPs impact adult asthma patients. We sought to examine an adult population for associations between rs7216389 (17q21-associated SNP) and features of asthma including fractional exhaled nitric oxide (FeNO), eosinophil counts, and age of asthma onset.

Methods

Subjects were genotyped at SNP rs7216389. The geometric mean of FeNO measurements and peripheral blood eosinophil counts from 2008 to 2015 were collected. Demographics and medical history were collected including self-reported allergy diagnoses and age of asthma onset. Eosinophils, monocytes, and peripheral blood mononuclear cells (PBMCs) were isolated for the examination of ORMDL3 expression.

Results

FeNO levels from 157 genotyped subjects (31CC, 72CT, and 54TT) and peripheral eosinophil counts from 252 genotyped subjects (46CC, 122CT, and 84TT) were analyzed. In a sub-group analysis of asthma subjects, the number of attributable T alleles was associated with significantly lower age of asthma onset (P=0.03) and greater FeNO levels (geometric mean 30.0 ppb TT, 20.0 ppb CT, 20.0 ppb CC, P=0.02). In the total cohort of subjects, the T allele was associated with a higher percentage of individual eosinophil counts >200/mm³ (45% TT, 26% CT, 24% CC, P=0.005). Eosinophils expressed ORMDL3 mRNA and protein.

Conclusion

In adult subjects, the number of T alleles at SNP rs7216389 corresponds to significantly greater FeNO levels and peripheral eosinophil counts. The expression of ORMDL3 in eosinophils suggests that they may participate in mediating the asthma risk associated with the 17q21 locus.

ORMDL3 Facilitates the Survival of Splenic B Cells via an ATF6α-Endoplasmic Reticulum Stress-Beclin1 Autophagy Regulatory Pathway

The genetic association of orosomucoid-like 3 (ORMDL3) with an array of immunoinflammatory disorders has been recently unraveled in multiple ethnic groups, and functional exploration has received attention of the particular relevance of this gene in endoplasmic reticulum stress, lipid metabolism, and inflammatory response. In this study, we demonstrated the upregulation of ORMDL3 in both patients with systemic lupus erythematosus and lupus mice compared with controls. By establishing ORMDL3 knockout mice (Ormdl3^-/-), we showed that silencing Ormdl3 in vivo significantly decreased the proportions of mature B lymphocytes and transitional 2B cells in spleen and B1a cells from abdominal cavity perfusion fluid, the secretion of IgG and IgM, and the expression of Baff. Additionally, knockdown of Ormdl3 augmented the apoptosis of total splenic cells and splenic CD19⁺ B cells but did not affect B cell proliferation and cell cycle. Subsequently, we in vitro and in vivo demonstrated that ORMDL3 potentially mediates the autophagy via the ATF 6-Beclin1 autophagy pathway, and it facilitates the survival of splenic B cells via promoting autophagy and suppressing apoptosis. Taken together, we uncovered a role of ORMDL3 in fine-tuning B cell development and survival, besides highlighting a potential mechanism by which ORMDL3 regulates autophagy via ATF6 pathway.

Chromosome 17q21 Genes ORMDL3 and GSDMB in Asthma and Immune Diseases

Chromosome 17q21 contains a cluster of genes including ORMDL3 and GSDMB, which have been highly linked to asthma in genome-wide association studies. ORMDL3 is localized to the endoplasmic reticulum and regulates downstream pathways including sphingolipids, metalloproteases, remodeling genes, and chemokines. ORMDL3 inhibits serine palmitoyl-CoA transferase, the rate-limiting enzyme for sphingolipid biosynthesis. In addition, ORMDL3 activates the ATF6α branch of the unfolded protein response which regulates SERCA2b and IL-6, pathways of potential importance to asthma. The SNP-linking chromosome 17q21 to asthma is associated with increased ORMDL3 and GSDMB expression. Mice expressing either increased levels of human ORMDL3, or human GSDMB, have an asthma phenotype characterized by increased airway responsiveness and increased airway remodeling (increased smooth muscle and fibrosis) in the absence of airway inflammation. GSDMB regulates expression of 5-LO and TGF-β1 which are known pathways involved in the pathogenesis of asthma. GSDMB is one of four members of the GSDM family (GSDMA, GSDMB, GSDMC, and GSDMD). GSDMD (located on chromosome 8q24 and not linked to asthma) has emerged as a key mediator of pyroptosis. GSDMD is a key component of the NLPR3 inflammasome and is required for its activation. GSDMD undergoes proteolytic cleavage by caspase-1 to release its N-terminal fragment, which in turn mediates pyroptosis and IL-1β secretion. Chromosome 17q21 has not only been linked to asthma but also to type 1 diabetes, inflammatory bowel disease, and primary biliary cirrhosis suggesting that future insights into the biology of genes located in this region will increase our understanding of these diseases.