Sputum metabolomic profiling revels metabolic pathways and signatures
associated with inflammatory phenotypes in patients with asthma
Abstract
Background: The molecular links between metabolism and
inflammation that drive different inflammatory phenotypes in asthma are
poorly understood. Objectives: To identify the metabolic
signatures and underlying molecular pathways of different inflammatory
asthma phenotypes. Method: In the discovery set (n=119),
untargeted ultra-high performance liquid chromatography–mass
spectrometry (UHPLC-MS) were applied to characterize the induced sputum
metabolic profiles from asthmatic patients classified by different
inflammatory phenotypes using orthogonal partial least-squares
discriminant analysis (OPLS-DA) and pathway topology enrichment
analysis. In the validation set (n = 114), differential metabolites were
selected to perform targeted quantification. Correlations between
targeted metabolites and clinical indexes in asthma patients were
analyzed. Logistic and negative binomial regression models were
established to assess the association between metabolites and severe
asthma exacerbation. Results: 77 differential metabolites were
identified in the discovery set. Pathway topology analysis uncovered
that histidine metabolism, glycerophospholipid metabolism, nicotinate
and nicotinamide metabolism, linoleic acid metabolism, phenylalanine,
tyrosine and tryptophan biosynthesis were involved in the pathogenesis
of different asthma phenotypes. In the validation set, 24 targeted
quantification metabolites were significantly differentially expressed
between asthma inflammatory phenotypes. Finally, adenosine
5’-monophosphate (RRadj = 1.000, 95%CI = [1.000, 1.000], P =
0.050), allantoin (RRadj = 1.000, 95%CI = [1.000, 1.000], P
= 0.043) and nicotinamide (RRadj = 1.001, 95%CI = [1.000, 1.002],
P = 0.021) were demonstrated to predict severe asthma
exacerbation rate ratios. Conclusions: Different inflammatory
asthma phenotypes have specific metabolic profiles in induced sputum.
The potential metabolic signatures may serve as identification and
therapeutic target in different inflammatory asthma phenotypes.