Background Morbidity and mortality from COVID‐19 caused by novel coronavirus SARS‐CoV‐2 is accelerating worldwide, and novel clinical presentations of COVID‐19 are often reported. The range of human cells and tissues targeted by SARS‐CoV‐2, its potential receptors and associated regulating factors are still largely unknown. The aim of our study was to analyze the expression of known and potential SARS‐CoV‐2 receptors and related molecules in the extensive collection of primary human cells and tissues from healthy subjects of different age and from patients with risk factors and known comorbidities of COVID‐19. Methods We performed RNA sequencing and explored available RNA‐Seq databases to study gene expression and co‐expression of ACE2, CD147 (BSG), and CD26 (DPP4) and their direct and indirect molecular partners in primary human bronchial epithelial cells, bronchial and skin biopsies, bronchoalveolar lavage fluid, whole blood, peripheral blood mononuclear cells (PBMCs), monocytes, neutrophils, DCs, NK cells, ILC1, ILC2, ILC3, CD4+ and CD8+ T cells, B cells, and plasmablasts. We analyzed the material from healthy children and adults, and from adults in relation to their disease or COVID‐19 risk factor status. Results ACE2 and TMPRSS2 were coexpressed at the epithelial sites of the lung and skin, whereas CD147 (BSG), cyclophilins (PPIA andPPIB), CD26 (DPP4), and related molecules were expressed in both epithelium and in immune cells. We also observed a distinct age‐related expression profile of these genes in the PBMCs and T cells from healthy children and adults. Asthma, COPD, hypertension, smoking, obesity, and male gender status generally led to the higher expression of ACE2‐ and CD147‐related genes in the bronchial biopsy, BAL, or blood. Additionally, CD147‐related genes correlated positively with age and BMI. Interestingly, we also observed higher expression of CD147‐related genes in the lesional skin of patients with atopic dermatitis. Conclusions Our data suggest different receptor repertoire potentially involved in the SARS‐CoV‐2 infection at the epithelial barriers and in the immune cells. Altered expression of these receptors related to age, gender, obesity and smoking, as well as with the disease status, might contribute to COVID‐19 morbidity and severity patterns.

During the past years, there has been a global outbreak of allergic diseases, presenting a considerable medical and socioeconomical burden. A large fraction of allergic diseases is characterized by a type 2 immune response involving Th2 cells, type 2 innate lymphoid cells, eosinophils, mast cells, and M2 macrophages. Biomarkers are valuable parameters for precision medicine as they provide information on the disease endotypes, clusters, precision diagnoses, identification of therapeutic targets, and monitoring of treatment efficacies. The availability of powerful omics technologies, How to cite this article: Ogulur I, Pat Y, Ardicli O, et al. Advances and highlights in biomarkers of allergic diseases.

Allergic diseases and asthma are heterogenous chronic inflammatory conditions with several distinct complex endotypes. Both environmental and genetic factors can influence the development and progression of allergy. Complex pathogenetic pathways observed in allergic disorders present a challenge in patient management and successful targeted treatment strategies. The increasing availability of high-throughput omics technologies, such as genomics, epigenomics, transcriptomics, proteomics, and metabolomics allows studying biochemical systems and pathophysiological processes underlying allergic responses. Additionally, omics techniques present clinical These different cellular components are tightly interconnected with TA B L E 1 Summary of methods, protocols, and data analysis pipelines most frequently used in omics approaches for allergic diseases research Methods and protocols Data analysis pipeline Mechanisms of allergic diseases Genomics and transcriptomics Microarray 181,182GWAS 183 and RNA microarray bioinformatics 184,185