Altered gut bacteria may contribute to metabolic disorders in SMA: Study

Abundance of certain bacteria was found significantly different in SMA children

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Alterations to the composition of intestinal microbes — called the gut microbiome — in spinal muscular atrophy (SMA) patients may contribute to certain metabolic disorders that are commonly seen in patients, according to a recent study.

Scientists identified a number of altered gut bacteria in children with SMA relative to healthy children, some of which correlated with dysregulated lipid metabolites — small molecules involved in fat metabolism — found in the blood.

Still, given that the study is the “first study on the gut microbiome of patients with SMA worldwide,” additional research is needed to establish the observed relationships, according to investigators.

The study, “The Alterations of Gut Microbiome and Lipid Metabolism in Patients with Spinal Muscular Atrophy,” was published in Neurology and Therapy.

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Metabolic disorders raise risk of heart and liver disease

Nutritional and metabolic problems are common among SMA patients. In particular, patients are susceptible to lipid metabolic disorders, or those marked by problems metabolizing fat molecules.

For example, studies have found that children with SMA are highly prone to dyslipidemia, a term referring to high blood levels of cholesterol or other fats. In turn, these disorders can raise the risk of heart and liver disease for patients.

Yet, the mechanisms underlying these metabolic issues aren’t known.

Patients with other neurological conditions, such as Alzheimer’s and Parkinson’s diseases, exhibit substantial abnormalities in their gut microbiome — the collection of bacteria, fungi, and viruses that inhabit the intestinal tract.

In turn, alterations to the microbiome can have important effects on the body’s metabolic functions, and may drive disease-related metabolic changes, according to the researchers. As such, it’s possible that changes to the gut microbiome are related to the lipid metabolism alterations observed in SMA patients.

To explore this possibility, a team at Zhejiang University School of Medicine, in China, examined microbe and metabolite compositions in 15 pediatric SMA patients followed at their center and compared them to samples from 17 healthy children, who served as the control group.

Alterations to the intestinal microbiota may be connected with the lipid metabolism disorders in patients with SMA, [which] may help explore the management of metabolic complications in such patients.

Patients, who were under 18 and had SMA types 2 or 3, were not using any disease-modifying SMA therapies. The group included six boys and nine girls with SMA, and the median age was 7.6. The control group was generally well-matched to SMA patients in terms of demographics and nutritional status.

Fecal samples were collected to examine microbe diversity, and blood samples were used to look at metabolites.

While the overall diversity of gut bacteria did not differ between SMA patients and healthy children, the abundance of certain bacteria was significantly different between the two groups.

Specifically, GordonibacterRuminiclostridiumEnormaLawsonellaFrisingicoccus, and Anaerofilum bacteria were found at a significantly higher abundance in SMA samples than healthy ones.

Differences in metabolic profiles were also observed between the SMA and control groups, with nearly 1,000 metabolites, or products of the overall metabolism, being found at different levels in the blood of SMA patients.

More specifically, there were 56 kinds of lipids or lipid-like molecules, involved in a range of different signaling pathways, that significantly differed in patients and controls.

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Certain microbes seem to correlate with levels of lipid metabolites in blood

Taking both analyses into account, the scientists identified a number of microbes taken from fecal samples that seemed to correlate with levels of lipid metabolites in the blood, overall suggesting “there may be a link between the two phenomena,” the researchers wrote.

For example, Ruminiclostridium bacteria, which were found to be abundant in SMA samples, were negatively associated with lipid metabolites such as coriolic acid and thromboxane B2. In other words, higher levels of the bacteria were linked to lower levels of these metabolites.

The findings suggest “that alterations to the intestinal microbiota may be connected with the lipid metabolism disorders in patients with SMA, [which] may help explore the management of metabolic complications in such patients,” the researchers wrote.

Still, additional studies are needed to better understand the potential relationships between microbes and metabolites, the researchers noted.

In particular, because clinical factors such as the degree muscle weakness and chronic constipation could influence the microbiome, additional research is needed to “observe whether the abundance and diversity of the intestinal microbiome will alter with disease prognoses.”