Scientists have named a possible cause of immune disorders in Down syndrome

People with Down syndrome may be more susceptible to infections, but the causes of their immune system are not fully understood. American researchers have found signs of a previously overlooked metabolic pathway that may be associated with inflammation and immune disorders. It is too early to talk about what exactly the scientists have found out and why, in the "Izvestia" article.

Why scientists study immunity in Down syndrome

Down syndrome is associated with the presence of an additional copy of chromosome 21. It contains genes that affect the functioning of different body systems. Researchers have long been trying to understand why people with this syndrome have immune response patterns and an increased risk of complications from certain infections.

One of the possible participants in this process is hydrogen sulfide. In small amounts, it is produced by cells and is involved in signal transmission. However, an excess of this substance can disrupt their work. We are talking about hydrogen sulfide, which is formed inside the body, and not about exposure to gas from the environment.

Previously, increased hydrogen sulfide formation in Down syndrome was mainly associated with the CBS gene located on chromosome 21. It is responsible for the production of an enzyme capable of participating in this process.

What the blood test showed

A team from Texas A&M University studied blood sample data from 270 people with Down syndrome and 146 people without it. The scientists compared the activity of genes and the content of proteins, including those related to the work of immune cells. This approach allows us to see which molecular processes differ between groups, but by itself does not prove the cause of diseases.

One of the most persistent differences was the increased activity of the SOD1 gene in people with Down syndrome. This gene is also located on chromosome 21 and is responsible for the formation of the enzyme superoxide dismutase 1. Under normal conditions, the enzyme helps cells to cope with certain reactive oxygen species, substances that, when accumulated, can damage cellular structures.

However, the researchers did not find an equally convincing increase in the level of CBS protein in the studied immune cells. This led them to take a closer look at other ways in which cells can produce hydrogen sulfide.

This result does not refute all previous data on CBS: the indicators may vary depending on the tissue being examined and the method used. It shows that other mechanisms should be considered to explain the changes in the studied cells.

What role can the SOD1 gene play?

The authors drew attention to the pathway of metabolism involving the MPST enzyme. It is able to participate in the formation of hydrogen sulfide from compounds that the cell receives during the processing of amino acids. According to the researchers, the increased activity of SOD1 is associated with changes that cause cells to receive more cysteine, one of the starting substances for these reactions.

In other words, scientists have proposed a possible chain: increased SOD1 activity is accompanied by a change in cellular metabolism, after which more hydrogen sulfide can be formed through the MPST pathway. Such a mechanism could help explain some of the features of inflammatory and immune processes in Down syndrome.

The work revealed a combination of changes in the activity of genes and proteins, which is consistent with the proposed mechanism. Further research is needed to determine whether this particular pathway leads to an excess of hydrogen sulfide and how much it affects the risk of infection in specific people.

Is it possible to create a treatment based on the discovery?

The results indicate a direction for the search for therapy: scientists want to understand whether it is possible to influence the exchange of hydrogen sulfide and thereby improve cell function. However, the study did not test the drug in humans and did not show that exposure to SOD1 or MPST reduces the incidence of infections.

Separately, Kent's group is studying nanoparticles capable of participating in the conversion of hydrogen sulfide. According to the researchers, preliminary tests of such particles in experiments related to the condition of bones in mice with genetic characteristics of Down syndrome have yielded encouraging results. But data on animal bone tissue cannot be transferred to the treatment of immune disorders in humans: these are different research tasks.

So far, the practical significance of the work lies in a more precise formulation of the question. If the proposed pathway is confirmed in subsequent experiments, scientists will be able to test whether exposure to it changes the functioning of immune cells and, ultimately, the health of people with Down syndrome. Clinical recommendations based on this discovery are still far away.