Introduction
Chronic obstructive pulmonary disease
(COPD) is a complex disease with both
genetic and environmental determinants,
the most important of which is cigarette
smoking. However, genetic variations like
severe a1-antitrypsin deficiency (AATD)
is known as a genetic risk factor for
COPD. Severe AATD patients present ...»»»»
Introduction
Chronic obstructive pulmonary disease
(COPD) is a complex disease with both
genetic and environmental determinants,
the most important of which is cigarette
smoking. However, genetic variations like
severe a1-antitrypsin deficiency (AATD)
is known as a genetic risk factor for
COPD. Severe AATD patients present an
heterogeneous respiratory clinical evolution
not explained by sociodemographic
or clinical factors. We analyzed the
gene-expression profiles of blood samples
collected from AATD Pi*ZZ patients and
healthy controls to identify differentialy
expressed mRNA and miRNAs that may
be involved in the progression of the
AATD. However, this first analysis are
based on the comparison between severe
and mild AATD Pi*ZZ patients.
Methods
In this pilot high-throughput microarray
experiment, RNA and miRNA microarrays
hibridization was carried out using
Genechip Human Gene Array Plate 2.1
and Genechip miRNA array plate 4.1
respectively. Background correction and
quantile normalization were performed
for the raw array data using the Oligo
R package. Limma (Linear Models for
Microarray Data) package was used to
perform statistical testing of differential
mRNA and miRNA expression between
the 2 study groups defined as having
a p<0.05 with at least 1.5-fold change
(FC) (logFC 0.58) between the groups.
Functional and enrichment analysis
were also performed using the Kyoto
Encyclopedia of Genes and Genomes
(KEGG) and Gene-ontology (GO) terms.
Finally, an integration of miRNA DEGs
and their target mRNA DEGs was
performed using ”multiMiR” R package.
All the analysis was performed using R
Studio (3.2.5 version).
Results
A total of 12 PiZZ AATD patients (n=6
in severe group and n=6 in mild disease
group) were included in this pilot
high-throughput microarray experiment.
Both AATD groups presented similar
characteristics in terms of current age,
gender, exacerbations, comorbidities,
replacement treatment and time from the
last infusion. Severe patients were diagnosed
younger than mild patients and all
of them received inhaled corticosteroids
(ICS). Two patients from the severe group
were current smokers and therefore were
not receiving replacement therapy.
Limma analysis was finally performed in 4 severe and 6 mild patients according
to quality control results. A total of
205 DEGs (114 upregulated and 91
downregulated) and 28 miRNA with
different expression (20 upregulated and
8 downregulated) were observed in severe
PiZZ AATD compared to mild patients.
Of those, we found a validated interaction
between hsa-miR-335-5p and 12 target
upregulated mRNA. These transcripts
participate dierctly in important pathways
like cytokine-mediated signaling pathway,
MAPK /mk2 signaling cascade, JNK
cascade and angiogenesis.
Conclusions
Despite the limitations, the findings
reported in this analysis provide valuable
information about the different
gene profile of severe PiZZ AATD
patients. Hsa-miR-335-5p regulated
important transcription factors that are
involved in the activation of pathways
directly related to inflammation and
angiogenesis in severe PiZZ AATD
patients and could play an important
role in the pathogenesis of this rare
condition. Nevertheless, further analysis
are needed in order to validate our results.^^^^
