Published online Sep 28, 2019. doi: 10.3748/wjg.v25.i36.5543
Peer-review started: July 3, 2019
First decision: August 2, 2019
Revised: September 2, 2019
Accepted: September 9, 2019
Article in press: September 9, 2019
Published online: September 28, 2019
An altered (dysbiosis) and unhealthy status of the gut microbiota is usually responsible for a reduction of short chain fatty acids (SCFAs) concentration. SCFAs obtained from the carbohydrate fermentation processes are crucial in maintaining gut homeostasis and their determination in stool samples could provide a faster, reliable and cheaper method to highlight the presence of an intestinal dysbiosis and a biomarker for various gut diseases. We hypothesize that different intestinal diseases, such as celiac disease (CD), adenomatous polyposis (AP) and colorectal cancer (CRC) could display a particular fecal SCFAs’ signature.
To compare the fecal SCFAs’ profiles of CD, AP, CRC patients and healthy controls, using the same analytical method.
In this cross-sectional study, we defined and compared the SCFAs’ concentration in fecal samples of 9 AP, 16 CD, 19 CRC patients and 16 healthy controls (HC). The SCFAs’ analysis were performed using a gas-chromatography coupled with mass spectrometry method. Data analysis was carried out using Wilcoxon rank-sum test to assess pairwise differences of SCFAs’ profiles, partial least squares-discriminate analysis (PLS-DA) to determine the status membership based on distinct SCFAs’ profiles, and Dirichlet regression to determine factors influencing concentration levels of SCFAs.
We have not observed any difference in the SCFAs’ amount and composition between CD and healthy control. On the contrary, the total amount of SCFAs was significantly lower in CRC patients compared to HC (P = 0.044) and CD (P = 0.005). Moreover, the SCFAs’ percentage composition was different in CRC and AP compared to HC. In detail, HC displayed higher percentage of acetic acid (P value = 1.3 × 10-6) and a lower amount of butyric (P value = 0.02192), isobutyric (P value = 7.4 × 10-5), isovaleric (P value = 0.00012) and valeric (P value = 0.00014) acids compared to CRC patients. AP showed a lower abundance of acetic acid (P value = 0.00062) and higher percentages of propionic (P value = 0.00433) and isovaleric (P value = 0.00433) acids compared to HC. Moreover, AP showed higher levels of propionic acid (P value = 0.03251) and a lower level of isobutyric acid (P value = 0.00427) in comparison to CRC. The PLS-DA model demonstrated a significant separation of CRC and AP groups from HC, although some degree of overlap was observed between CRC and AP.
Analysis of fecal SCFAs shows the potential to provide a non-invasive means of diagnosis to detect patients with CRC and AP, while CD patients cannot be discriminated from healthy subjects.
Core tip: An altered gut microbiota is usually responsible for a reduction of short chain fatty acids (SCFAs) concentration. In this study, we analyse through gas-chromatography coupled with mass spectrometry the fecal SCFAs’ concentration in patients with various gut diseases [celiac disease (CD), adenomatous polyposis (AP) and colorectal cancer (CRC)]. Altought the small sample size of study does not allow us to reach definitive conclusions, our findings suggest the existence of a fecal SCFAs fingerprint in patients with CRC amd AP distinguishable from healthy controls. On the contrary, no differences between celiac patients and healthy controls was observed.