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Caution, metabolic syndrome

The adipose tissue cells are enlarged and arranged less than normal in mice lacking perforin-rich dendritic cells (above), compared to the same tissue in normal mice (below). Small image below left: crown-like structures within the adipose tissue (above, dark brown) indicate an increased inflammatory process within the tissue
Usually we tend to think of the immune system as a mechanism that protects us from bacteria, viruses and other invaders. But this system also has other - and surprising - roles. Weizmann Institute of Science scientists have identified a small subset of cells of the immune system that apparently prevent the metabolic syndrome, which manifests itself in obesity, high blood pressure, and high levels of sugar and cholesterol in the blood.

The connection between the immune system and obesity is known, but the previous studies on this topic were conducted on mice that received high-fat food. In contrast, the new study by the institute's scientists, which was recently published in the scientific journal Immunity, was done in mice that received normal food. This is how the study showed that the immune system can play a role in obesity and the other components of the metabolic syndrome, without any connection to fatty food.

The research focused on dendritic cells, which function as a kind of sentinel of the immune system, and warn against various dangers. The scientists studied a small subset of dendritic cells that contain the protein perforin, which allows them to kill other cells when necessary. To find out the role of these dendritic cells in the body, scientists led by Prof. Yair Reisner, from the department of immunology at the Weizmann Institute of Science, created mice without dendritic cells rich in perforin. To their surprise, the scientists discovered that the weight of these mice increased significantly, after which they developed metabolic syndrome.

Later, the scientists discovered that the fat tissue of these mice contains large amounts of T cells of the immune system, which cause inflammation. When the scientists omitted these T cells - the mice did not get fat. This finding indicates that perforin-rich dendritic cells control certain T cells, thus preventing the formation of the metabolic syndrome.

The adipose tissue cells are enlarged and arranged less than normal in mice lacking perforin-rich dendritic cells (above), compared to the same tissue in normal mice (below). Small image below left: crown-like structures within the adipose tissue (above, dark brown) indicate an increased inflammatory process within the tissue

The study brought new insights into this syndrome, but in addition to that, it also sheds new light on the autoimmune phenomena. Mice lacking the perforin-rich dendritic cells had a tendency to develop an autoimmune disease similar to multiple sclerosis in humans. Now the scientists propose to investigate whether these control cells are also missing in humans suffering from certain autoimmune diseases.

The research was conducted by members of Prof. Reisner's group and their research partners from the Department of Immunology: Dr. Yael Klionsky, Bar Natanzon Levy, Dr. Elias Shatzen, Dr. Chava Rosen, Dr. Sion Kagan, Dr. Liat Bar-On, Prof. Stefan Jung, Dr. Eric Shiprot, Dr. Shlomit Reich-Zeliger, Dr. Nir Friedman, Dr. Rina Aharoni, Prof. Ruth Arnon, Oren Yifa and Dr. Anna Ahronovich.

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