Introduction
Volatile organic compounds (VOCs) derived from gut dietary non-starch polysaccharides fermentation become detectability in biological fluids due to the impairment of the gut permeability (“leaky-gut syndrome”) occurring in several pathological contexts such as insulin-resistance (IR)-related chronic disorders. The urinary VOCs profile, configuring a specific disease biosignature, has been proposed as a useful non-invasive diagnostic tool. In Metabolic dysfunction Associated Fatty Liver Disease (MAFLD) affected patients, IR and Diabetes Mellitus Type 2 (T2DM) crucially promote the progression, according to the disease's natural history, from simple steatosis (SS) to steatohepatitis (NASH) and advanced fibrosis. However, despite the crucial role exerted by IR, MAFLD patients may be characterized by IR stigmata without T2DM as well as T2DM subjects may not be affected by hepatic steatosis.
Aims & Methods
In the present study, the differences in the urinary VOCs profile of T2DM, MAFLD, and MAFLD/T2DM patients were investigated and compared to define the MAFLD/T2DM group’s characteristics and to find out new features occurring when these two conditions coexist, otherwise not detectable in each pathological state. We consecutively enrolled T2DM, MAFLD, and MAFLD/T2DM patients. For each participant, anthropometrical, biochemical (including insulin levels assessment), and clinical data were recorded. A sample of morning urine after overnight fasting was also collected. The samples were immediately frozen and stored until the analysis. Headspace solid-phase microextraction (HS-SPME), coupled with gas chromatography-mass spectrometry (GC-MS), was used to identify VOCs in urine samples. Subsequently, VOCs previously isolated were profiled via a mass selective detector. VOCs classification was performed by matching mass spectra within the available database libraries and comparing their retention indices (RI) with literature data.
Results
13 T2DM, 13 MAFLD, and 13 MAFLD/T2DM patients were enrolled. All patients presenting hyperinsulinemia (insulin >24 microU/ml). VOCs profiles obtained by using acid pH extraction did not show statistical differences among the analyzed groups, while VOCs acquired in alkaline conditions revealed differences among the three groups. The multivariate and univariate data analysis showed 21 metabolites levels statistically significantly different in the urine of MAFLD/T2DM compared to T2DM (p=0.021) and MAFLD (p=0.031) subjects. Among these metabolites, 1-pentanol (A16), Pyridine (N5), Dimethyl sulfone (S3), and 1-piperidine carboxaldehyde (N19) were higher in MAFLD/T2DM subjects compared to T2DM patients; 3-heptanone (K10) and 3-octane (K13) were lower in MAFLD/T2DM subjects than MAFLD patients; 2-hexanone (K6) presented lower levels in MAFLD/T2DM patients in comparison to T2DM subjects.
Conclusion
VOCs’profiling could non-invasively discriminate insulin-resistant T2DM, MAFLD, and MAFLD/T2DM patients. Moreover, the highlighted different VOCs' signatures suggest specific pathogenetic mechanisms in MAFLD and T2DM to explore and remark MAFLD and T2DM coexistence as not the mere sum of two diseases.
References
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