Allergens, germs and asthma

S. aureus and IgE-mediated diseases: pilot or copilot? A narrative review

INTRODUCTION

S. aureus is a major opportunistic pathogen that has been implicated in the pathogenesis of several chronic inflammatory diseases including bronchial asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), chronic spontaneous urticaria (CSU), and atopic dermatitis. S. aureus can induce the production of both polyclonal and specific IgE that can elicit an inflammatory cascade.

AREAS COVERED

The link between the sensitization to S. aureus enterotoxins and the severity of several chronic inflammatory diseases is reviewed in detail, as well as its therapeutic implications.

EXPERT OPINION

An anti-IgE strategy to inhibit S. aureus enterotoxins would be a valid approach to treat several endotypes of severe asthma, CRSwNP and CSU in which IgE against S. aureus enterotoxins should represent, not only a marker of severity of the diseases but also a target of a treatment.

Expression of cPLA2γ mRNA and protein differs the response of PBMC from severe and non-severe asthmatics to bacterial lipopolysaccharide and house dust mite allergen

Chronic inflammation in asthmatics is initiated/exacerbated by many environmental factors, such as bacterial lipopolysaccharide and allergens. Phospholipase A₂ and histone acetyltransferase/deacetylases are enzymes involved in inflammatory process, particularly in lipid inflammatory mediators production and control of transcription of many inflammatory genes, respectively. The aim of the study was to identify differences in the inflammatory process in patients with severe and non-severe asthma, taking as a criterion expression of two groups of enzymes: phospholipases A₂ and histone acetyltransferases/deacetylases. Thirty-two patients with severe, non-severe atopic to house dust mite asthmatics and 14 healthy volunteers were recruited. Peripheral blood mononuclear cells were stimulated with Dermatophagoides pteronyssinus allergen (nDer p1) and bacterial lipopolysaccharide (LPS). The expression of phospholipases A₂ and histone acetyltransferases and deacetylases were assessed using TaqMan Low Density Array Cards. The protein expression was analyzed with immunoblot. Increased expression of phospholipase A2 Group IVC (PLA2G4C) and cytosolic phospholipase A2 gamma (cPLA₂γ) protein was observed in peripheral blood mononuclear cells (PBMC) from severe asthmatics in response to LPS and nDer p1, compared to non-severe asthmatics. nDer p1-stimulated PBMC from severe asthmatics exhibit induced expression of HDAC1 and similar trend was observed in protein concentration. Decreased expression of EP300 occurred in PBMC of severe asthmatics. PBMC from non-severe asthmatics showed decreased expression of HDAC2 and PLA2G15 after LPS treatment. In conclusion, in response to LPS and dust mite allergen, PBMC from severe and non-severe asthmatics modulate expression of selected phospholipase A₂, histone acetyltransferases and deacetylases, while increased expression of cPLA₂γ characterizes PBMC response from severe asthmatics.

Innate and Adaptive Immunity: ILC2 and Th2 Cells in Upper and Lower Airway Allergic Diseases

Advances in our understanding of the immune system, with the recent discovery of a parallel set of innate T lymphocytes, the innate lymphocytes (ILCs), have led to a reassessment of the pathogenesis of allergic and eosinophilic airway disorders, including allergic rhinitis (AR), asthma, and chronic rhinosinusitis with nasal polyps. We review current understanding of both elements of type-2 inflammatory responses and their relative influence in these common conditions and consider possible impacts of this on treatment selection.

Promoter region single nucleotide polymorphism of siglec-8 gene associates with susceptibility to allergic asthma

Aim: Siglec-8 is exclusively expressed on mast cells, eosinophils and basophils. Possible association of six siglec-8 single nucleotide polymorphisms (SNPs) with susceptibility to allergic asthma in the Azeri population of Iran was investigated in this study. Materials & methods: A total of 194 patients and 190 normal subjects were enrolled. PCR single strand conformation polymorphism (PCR-SSCP) was used to determine the genotypes of the studied SNPs. Results: The rs36498 showed significant association with allergic asthma (odds ratio [OR]: 0.65; p = 0.022) and the T allele was found as a protective allele (OR: 0.61; p = 0.008). Also, eosinophil count in the CC genotype was significantly higher than that in the other genotypes (p = 0.026). Conclusion: The rs36498 is thought to influence the expression level of siglec-8. Siglec-8 could be a potential therapeutic target for allergic asthma.