The green rhinestones in the photo are anything but valuable: They are so-called fat crystals. In the human body, they can trigger chronic inflammation, according to the results of a new study.
In some people, a rare genetic defect causes their cells to form malformed fats – so-called deoxysphingolipids – due to an altered enzyme. “These exotic molecules have the disadvantage that they can only be broken down very slowly,” explains Lars Kürschner from the University of Bonn. “In high concentrations, they also form crystal-like lumps in the affected cells.” The consequences of this disorder are serious.
Consequences of the mutation known to date include the death of nerve cells, which inhibits the sensation of pain, loss of hearing or early dementia. Those affected often suffer from skin damage that is difficult to heal or even becomes chronic. The reason: The large number of fat crystals in the cells severely restricts the function of the mitochondria – the cell’s own power plants. “This mainly affects the nerve cells,” says Kürschner.
He and his colleagues have also found that these defects occur not only in nerve cells, but also in connective tissue cells. This raised another question: “We asked ourselves whether the deoxysphingolipid crystals also have effects on the immune system,” explains Kürschner. To do this, the researchers examined macrophages – immune cells in the connective tissue that function as the body’s own garbage disposal.
The result showed that macrophages, like nerve or connective tissue cells, produce large amounts of deoxysphingolipids in the course of the disease. At the same time, in their function as “garbage trucks”, they also take in the fats of dead cells. You even get double the dose of fat crystals.
The consequences for the cells are analogous to those in nerve cells: the function of various cell components, such as the mitochondria, is disturbed. The immune cells respond by dismantling the damaged power plants in order to renew them. “Nerve cells and connective tissue cells do the same,” says Lauterbach. But the macrophages also activate a molecular complex that promotes inflammation. Because these messenger substances also attract other phagocytes, this effect is reinforced.
“One consequence of the accumulation of these pathological fats is therefore an inflammation that manifests itself,” explains the researcher. The results could also shed new light on a far more common ailment – diabetes. In diabetic patients, deoxysphingolipid production is also increased in some cells; why is still largely unknown. And doctors regularly observe severe chronic inflammation in diabetes, which contributes to the serious consequences of the disease.