In healthy people, the surface of the tissue (epithelia) that lines the airways of the lungs is covered by a liquid that protects the lungs from infection. The biochemical mechanisms of these defence systems are highly-complex, but in simple terms, lung cells, among other substances, also produce sodium bicarbonate, which dissolves in this liquid or makes it inhospitable to bacteria. In cystic fibrosis sufferers the protein, called CFTR, which enables (or ought to enable) bicarbonate and other molecules to cross the external wall of the cells to reach the protective liquid, however is defective, or absent, due to a genetic defect. All of this results in a gradual acidification of the lung tissue, which makes the lungs more susceptible to infection, and also causes the accumulation of mucus (which must then be drained regularly).
The US researchers discovered that amphotericin B makes holes in the membrane of the cells, opening “channels” that allow the bicarbonate and other molecules to pass through, regardless of the kind of genetic mutation that has caused the illness (there is a very large number of different kinds of cystic fibrosis). Amphotericin B practically works like the CFTR, as if it was a kind of prosthesis – write the researchers. Tested on the tissue of patients with different mutations of the disease, but also – as already stated – on animals (in particular, on pigs with cystic fibrosis), the drug was able to restore the transportation of the bicarbonate and other molecules, reduce acidity and re-establish the defence capacity of the lungs to values considered normal. Now it is hoped that tests will soon be carried out on patients, also because the drug has been approved for years, and is very cheap. In particular, researchers will attempt to find a formulation that enables amphotericin B to reach the lungs specifically, avoiding secondary damage.