International Journal of

Molecular Sciences

Editorial
Editorial of Special Issue “Molecular Mechanisms of Allergy
and Asthma”
Daniel P. Potaczek

Translational Inflammation Research Division & Core Facility for Single Cell Multiomics,
Philipps-University Marburg, 35043 Marburg, Germany; danppot@gmail.com

This Special Issue aggregates several high-quality original articles written by renowned
researchers. Those articles substantially differ in their scope, which is a natural consequence
of not only the broadness of the topic of the special issue, but also the multidimensional
character of molecular allergology as a field.
Two studies investigated the very beginnings of allergy, starting from the perinatal
period. Perveen and colleagues [1] reported protective effects of high neonatal T cell protein
kinase C zeta expression against the development of allergic diseases later in life to be
related to maturation of new-born T cells more towards type 1 helper T cells, with a decrease
in type 9 helper T cells. Acevedo et al. [2] in turn comparatively analyzed peripheral blood
mononuclear cell DNA methylation in mothers during pregnancy and their children
between the birth and 5 years of age. They observed an association between maternal or
offspring DNA methylation patterns and immunoglobulin E-mediated sensitization early
in life. Besides, several new candidate genes for atopy were identified.
Some other papers focused on specific mechanisms of allergic airway inflammation
characteristic for asthma. Bazan-Socha et al. [3] analyzed bronchial wall geometry and
reticular basement membrane thickness in the context of a bronchial epithelium transcrip-



tome profile in asthmatics. Their results suggested that being associated with a thicker


reticular basement membrane, the pro-fibrotic profile in the airway epithelial cell tran-
Citation: Potaczek, D.P. Editorial of
scriptome might contribute to asthma airway remodeling. In a methodologically robust
Special Issue “Molecular Mechanisms
study, Bruno and colleagues [4] demonstrated the importance of dynamin related pro-
of Allergy and Asthma”. Int. J. Mol.
tein 1-mediated mitochondrial fission for regulation of the pro-inflammatory response by
Sci. 2021, 22, 11580. https://doi.org/
respiratory epithelium and airway epithelial cell survival after exposure to house dust
10.3390/ijms222111580
mites. Richards and co-workers [5] showed that short-chain fatty acids, fermentation
metabolites from the gut microbiome, contributed to the recovery of barrier properties of
Received: 14 October 2021
Accepted: 19 October 2021
airway epithelial cells, which might be mediated by increasing the expression of zonula
Published: 27 October 2021
occludens-1, a tight junction protein contributing to the integrity of the epithelium. In turn,
van Heerden et al. [6] showed that long, asthma-associated form of thymic stromal lym-
Publisher’s Note: MDPI stays neutral
phopoietin downregulated the production of immunoglobulin A, which might negatively
with regard to jurisdictional claims in
affect the surveillance of mucosal surfaces in asthma. Amniai et al. [7] demonstrated that
published maps and institutional affil- natural killer cells from allergic donors were defective in their response to CC chemokine
iations. ligand 18, a CC chemokine constitutively highly expressed in human lungs and plasma
and upregulated during inflammatory and cancer processes in many organs, which might
participate in the defect in the natural killer cell activation observed in asthma. In a mouse
study, MacBeth et al. [8] showed that alterations in transcription factor binding and a novel
Copyright: © 2021 by the author.
variable dinucleotide repeat of variable length impacted the regulation of interleukin-6,
Licensee MDPI, Basel, Switzerland.
contributing to naturally occurring regulatory T cell plasticity important for interleukin-6-
This article is an open access article
related disease with impaired function of naturally occurring regulatory T cells. Finally,
distributed under the terms and Alhamdan and colleagues [9] investigated genome-wide expression patterns in purified
conditions of the Creative Commons CD4+ T cells obtained from asthmatic adults with or without obesity and healthy controls.
Attribution (CC BY) license (https:// They found interferon-related signaling pathways to be specifically overrepresented in
creativecommons.org/licenses/by/ obese asthmatics, while the gap junction and G protein-coupled receptor ligand bind-
4.0/). ing pathways were enriched in both asthma groups. The topological interconnection

Int. J. Mol. Sci. 2021, 22, 11580. https://doi.org/10.3390/ijms222111580 https://www.mdpi.com/journal/ijms

Int. J. Mol. Sci. 2021, 22, 11580 2 of 3

between interferon signaling and viral infection pathways in subjects with low type-2
obesity-associated asthma might define a complex mechanism underlying this phenotype.
Other allergic disorders have also been targeted. Bélanger and colleagues [10] sought
to find a differential microRNA pattern in eosinophils from patients presenting not only
with asthma but also other diseases included in the atopic march process, such as allergic
rhinitis or atopic dermatitis, and unaffected individuals. They found eighteen microRNAs
to be differentially expressed. Moreover, counts from these microRNAs made it possible to
cluster study individuals into groups that could be explained by the clinical characteristics
of the patients. Franke et al. [11] demonstrated interleukin-33 to generally foster the cy-
tokine producing apparatus of skin mast cells through operation at different levels and in
a potent cooperation with the high affinity immunoglobulin E receptor and MAS-related
G protein-coupled receptor X2. This suggested the role of interleukin-33 as an efficient
amplifier of skin inflammation in inflammatory dermatoses such as atopic dermatitis,
urticaria and psoriasis. The data obtained by Nieto et al. [12] indicated a novel mechanism
involved in controlling ocular allergic diseases, with α-melanocyte stimulating hormone
diminishing the concentration of interleukin-6 and -4, thus restoring the frequency of regu-
latory T cells and down-regulating CD4+ T cell activation. In addition, they demonstrated
the involvement of CD4+TLR4+ cells as an effector cell subset in allergic conjunctivitis.
Several further studies addressed food allergies or allergens. In a mouse model,
Abbring et al. [13] demonstrated raw milk-induced protection against food allergy symp-
toms to be accompanied by shifts in the gut microbiome. Siekierzynska and colleagues [14]
assessed whether factors such as the cultivation method, maturity stage, genotype, or type
of tissue might place an impact on the allergenic potential of apples. Their results made
it possible to distinguish between potentially low, medium, and highly allergenic apple
varieties. Mattison et al. [15] performed a microbiological, physicochemical, and immuno-
logical analysis of a commercial cashew nut-based yogurt, which indicated that it was not
suitable for individuals with a cashew nut allergy. Iweala and coworkers [16] investigated,
in turn, a unique type of allergy. They demonstrated that in alpha-gal syndrome, peripheral
blood T and B lymphocyte transcriptional states could differentiate between sensitized and
sensitized individuals.
Finally, this Special Issue comprises also a small set and state-of-the art review arti-
cles. While Nagata and Nishiyama [17] outlined the anti- and proinflammatory roles
of interleukin-10 in mast cell-mediated immune responses, Sroka-Tomaszewska and
Trzeciak [18] summarized and discussed the molecular mechanisms underlying atopic der-
matitis. The other three reviews referred to asthma. Whereas the article by di Palmo and col-
leagues [19] addressed the predictive role of biomarkers and genetics in childhood asthma
exacerbations, the work by Chiu and Huang [20] summarized the current state of knowl-
edge on the role of biologics and probiotics in asthma. Finally, Alashkar Alhamwe et al. [21]
outlined and discussed the knowledge on the role of extracellular vesicles in asthma.
I strongly believe that the articles belonging to this Special Issue are of interest to
many scientists and medical practitioners dealing with asthma and/or other allergies.

Conflicts of Interest: The author declares no conflict of interest.

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