Pneumonia Can Damage DNA

The number-one cause of death in children under the age of 5 worldwide has also been shown to harm DNA.

Certain strains of the bacterium that causes pneumonia, Streptococcus pneumoniae, causes DNA alterations in human lung cells, a team from the Singapore-MIT Alliance for Research and Technology (SMART) revealed. S. pneumoniae secretes hydrogen peroxide (Hâ‚‚Oâ‚‚) which seems to be responsible for causing double-strand breaks.

“There have been previous reports [of DNA damage] for certain bacteria, but nobody expects DNA damage to play a role in an acute infection like pneumonia,” the study’s lead author Prashant Rai, BS, MS, said in a news release.

Although Hâ‚‚Oâ‚‚ is often used to kill microorganisms, the findings show that the bacterium uses the formula to hurt the host. Previous influenza epidemics often turned deadly with the second bacterial infection of pneumonia, therefore, the team decided to further explore S. pneumoniae, reports one of the authors Vincent Chow, DipMicrobiol, MD, FRCPath, MBBS, MSc, PhD.

“It’s clearly tied to flu pathogenicity,” Chow explained. “We wanted to investigate if S. pneumoniae and its products, such as hydrogen peroxide, could inflict damage on DNA of the infected host.”

According to the work published in the Proceedings of the National Academy of Sciences, S. pneumoniae’s production of Hâ‚‚Oâ‚‚ — made possible by Streptococcus pyruvate oxidase (SpxB) – plays a role in the virulence and genotoxicity. Not only does the highly toxic Hâ‚‚Oâ‚‚ cause cells’ ends to break, but it can also lead to apoptosis (cell suicide). The severity of DNA damage – which takes place in a bacterial contact-independent way – corresponds to the extent of apoptosis.

“Secretion of hydrogen peroxide damages the DNA of lung cells, crippling the lungs’ defenses against invasion and making it easier for the bacteria to get into the bloodstream,” senior author Bevin Engelward, ScD, confirmed.

In addition, the researchers identified 2 strategies for combatting the DNA deterioration with the first being catalase. The enzyme was found to neutralize the Hâ‚‚Oâ‚‚ and as a result it stopped the damage from taking place. Another repair method was identified using Ku80. The team found that a deficiency of this protein led to more double-strand breaks, so sufficient levels are key for reconstruction.

This research suggests a possible need for future studies on DNA repair in pneumonia sufferers.