Is metabolic syndrome an autoimmune disease?
Problems with the immune system cause obesity
Researchers have found that when laboratory mice lack a certain type of immune cells, they become obese and develop high blood pressure, high cholesterol and diabetes. The detected phenomenon has not yet been observed in humans, but scientists already believe that it is possible to draw conclusions about the possible causes of metabolic syndrome – a combination of obesity, high blood pressure, a tendency to thrombosis, insulin resistance and an increase in the concentration of low-density lipoproteins in the blood.
The discovery was made in the course of research on a completely different problem – autoimmune diseases. Some cells of the human immune system contain special proteins – perforins, which destroy tumor cells, destroying their membrane. Immunologist Yair Reisner from the Weizmann Institute and his colleagues suggested that under certain conditions, dendritic cells containing perforin can cause the destruction of healthy cells of the body. In the course of testing this hypothesis, Reisner's group created mice using genetic engineering methods that lacked perforin-containing dendritic cells. Quite unexpectedly, it turned out that the mice gained weight dramatically and began to show other signs of metabolic syndrome.
Mice deprived of dendritic cells with perforin had high cholesterol levels, early signs of insulin resistance, and molecular markers associated with heart disease and high blood pressure were found in their blood. The study of the immune system of these mice showed that their ratio of T cells directing the immune response differs from the normal one. When the researchers removed these T cells, the absence of dendritic cells no longer caused obesity or metabolic syndrome in the animals.
Reisner suggests that dendritic cells containing perforin have another previously unknown function – to keep certain populations of T cells under control. If necessary, perforin is used to destroy unnecessary T cells. When this possibility disappeared in the body of experimental mice, excess T cells began to cause inflammation in adipose tissue, which led to a change in metabolism and weight gain.
Figure from an article in Immunity – VMAt the moment, researchers are working with human cell cultures, trying to establish whether something similar is happening in them.
If the assumption is confirmed, the discovered mechanism can be used to treat metabolic syndrome and obesity.
The results are reported in an article published by the journal Immunity (Zlotnikov-Klionsky et al., Performin-Positive Dendritic Cells Exhibit an Immuno-regulatory Role in Metabolic Syndrome and Autoimmunity).
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16.09.2015