Debilitating Consumption
Sunlight helps with a rarer form of tuberculosis, cutaneous tuberculosis - this has been known for more than a hundred years. Only now has an international research team found out how UV light stimulates the immune system via vitamin D. It is a killer: Every year, tuberculosis kills two million people worldwide - even though the disease is actually curable: Various antibiotics kill Mycobacterium tuberculosis, the causative agent of tuberculosis - provided the patients take the medication regularly and in sufficient quantities use for a long time.
But this is exactly where the problem lies: In many countries, the he althcare system is inadequate, patients have no access to therapeutics or stop treatment too early. The result: tuberculosis has been spreading again since the end of the last century, and bacterial strains are emerging that antibiotics can no longer harm.
In order not to be at the mercy of these resistant germs, new, effective drugs must be developed. That is why scientists are trying to understand the interaction between bacteria and humans in order to be able to design new therapy strategies.
A multinational working group headed by Robert Modlin from the University of California in Los Angeles has now elucidated the role of vitamin D in the immune system's fight against tuberculosis. The team studied macrophages, the immune cells in which tuberculosis pathogens try to hide from the body's attacks. The researchers first turned their attention to a specific protein, the 'Toll-like receptor', which triggers an immune system attack against microorganisms.
When the scientists activated this receptor, the tuberculosis bacteria in the macrophages died. To find out why, the researchers analyzed which genes were switched on by activating the Toll-like receptors. It was shown that the stimulated cells increasingly form receptors for vitamin D and a precursor of vitamin D. In response to these processes, the peptide cathelicidin is produced, which in turn kills the tuberculosis pathogens hidden in the macrophages. Vitamin D therefore seems to play a role in the fight against tuberculosis.
Now the scientists turned their attention to another phenomenon that is interesting in this context: dark-skinned people suffer from consumption more often than light-skinned people, and the disease is often more severe in them. Could this be due to vitamin D? Vitamin D production is lower in dark-skinned people due to the intense pigmentation of the skin, since the body needs sunlight to produce this vitamin.
When the research team examined the blood of black and light-skinned Americans, they found significantly less vitamin D and also lower production of the antimicrobial peptide cathelicidin than whites. However, if the scientists added some provitamin D to the blood serum of the dark-skinned people, more cathelicidin was synthesized accordingly. Apparently vitamin D actually helps to reduce consumption.
Scientists think it is possible that the simple and inexpensive supply of vitamin D could support the natural immune response against infectious diseases such as tuberculosis, especially in black people.
