Antibiotic with human origin

Washing hands with soap helps fight germs by destroying the lipid layer in the cell membranes of bacteria or the protective shell of viruses. US researchers have now discovered a similar substance in humans. According to an article in the journal Science, it is able to kill various bacteria – including salmonella and gram-negative bacteria. The newly discovered substance belongs to the lipoproteins and thus to the so-called cell-autonomous immune defense system. The production of the substance apolipoprotein APOL3 is only activated by complex mechanisms of the immune system after germs have invaded human cells.

Similar to surfactants, APOL3 has a water-soluble and a fat-soluble part. The latter allows the peptide to penetrate the bacterial biomembrane and dissolve it. After damage to the outer bacterial membrane by other substances, APOL3 then breaks down the inner membrane into small sections, which leads to the death of the bacteria.

A simple trick is used to protect against the destruction of its own human cell membranes: the cholesterol content of the cell membranes differs significantly from one bacterium to another. This enables APOL3 to selectively differentiate between human origin and foreign bodies.

These new findings could make an important contribution to the fight against various microbes, especially as increasing antibiotic resistance will further reduce the effectiveness of this type of therapy. According to a current estimate for 2019, more than 1.2 million deaths per year can already be attributed to antibiotic resistance. This means that antibiotic resistance is responsible for more deaths than HIV and malaria combined.

Sources:

• „A human apolipoprotein L with detergent-like activity kills intracellular pathogens“, Ryan G. Gaudet et al.; Science, DOI: 10.1126/science.abf8113
• https://www.wissenschaft-aktuell.de/
• https://www.spiegel.de/