MOSCOW, July 29. /TASS/ Russian scientists from the Federal Research and Clinical Centre of Physical-Chemical Medicine, the Koltzov Institute of Developmental Biology, and the Moscow Institute of Physics and Technology (MIPT) have shown that the human immune system’s proteins can play a key role in fighting against chlamydia infections, as reported by MIPT’s press service. The results of the study have been recently published in the journal, Infection and Immunity.

"In the following report, this research’s findings can be applied to rationalize the exact mechanism of how proteins act on chlamydiae and to assist in developing a medication to treat chlamydia," comments Pavel Bobrovsky, one of the authors of the study.

What is chlamydiosis?

Chlamydiae are parasite bacteria which cause chlamydiosis, an infection that affects more than 90 million people a year. Chlamydia is one of the most common sexually transmitted diseases and causing the inflammation of various organs from urogenital apparatus.

During their life cycle, chlamydiae constantly change their shape from elementary bodies (EBs) and reticulate bodies (RBs). EBs are strongly protected from the environment and other microorganisms, which helps them survive in an intracellular space and allows them to spread and infect new cells. RBs are able to survive only inside the host cell membrane but this form is favorable to activate metabolism and a reproduction cycle. Since these bacteria are so versatile, they hinder the treatment of chlamydia.

The breakthrough Russian scientists discovered

For treating chlamydia, Russian scientists have suggested using the specific proteins of human immune systems which are capable of recognizing peptidoglycan, a membrane component of some bacteria. These proteins (PGLYRPs) are able to attach to bacteria, thereby disrupting the regulation of the intracellular metabolism and killing off the microorganism. In a previous study, it was shown that these proteins are able to destroy Escherichia coli and Bacillus subtilis bacteria. This gave scientists the idea to research whether these peptidoglycan-recognizing proteins could also inhibit chlamydia.

To check this hypothesis, researchers added PGLYRP solutions to human cell cultures and then infected the cells with Chlamydia trachomatis. Forty-eight hours later, they counted the number of inclusions and compared it with control samples. It appears that PGLYRPs actually did inhibit the chlamydia infection. The number of chlamydial inclusions in the samples with proteins was 10 times smaller than in the control sample. However, a significant antichlamydial effect has only been observed with protein concentrations 20 times higher than for E. coli and B. subtilis. According to the study’s authors, this can be explained by the sophisticated life cycle of chlamydias.

Moreover, the researchers have tracked the time evolution in the gene expression level (expression is the synthesis of substances responsible for the transmission of hereditary information through RNA). It turned out that in the control sample it remained at a base level, whereas in the cultures with PGLYRPs two peaks can be easily distinguished - 1 hour and 72 hours after the infection. At these times, the chlamydiae form elementary bodies and scientists predicted that they would be more vulnerable to PGLYRPs at this particular stage of their life cycle, which has been also proven experimentally.