Cannibalistic Process in Cells May Help Treat Intracellular Bacterial Infections

August 7, 2009

A cannibalistic process in cells may be the key to prevent harmful bacteria from becoming successful pathogens, and a decrease in this process may also lead to problems in the way that the intestinal tract handles infections.

A cannibalistic process in cells may be the key to prevent harmful bacteria from becoming successful pathogens, and a decrease in this process may also lead to problems in the way that the intestinal tract handles infections, according to new research from scientists at the University of Texas Southwestern (UT Southwestern).

Autophagy, the process by which cells destroy unwanted or damaged parts that is also used to maintain the health of the cell, “prevents harmful bacteria such as Salmonella from becoming successful pathogens.” According to Dr. Beth Levine, chief of the division of infectious diseases at UT Southwestern, professor of internal medicine and microbiology, and senior author of the study, the results also suggest that decreases in autophagy “may lead to abnormalities in the way the intestinal tract deals with bacterial infections.”

For the study, the researchers genetically engineered two organisms, Caenorhabditis elegans and Dictyostelium discoideum, to lack active autophagy genes. They then studied the impact of Salmonella infections on the organisms, which showed that the organisms with inactive autophagy genes “fared far worse than those with active ones.” According to Levine, “rather than being targeted for elimination, the Salmonella bacterium was able to invade the host cells, where it started replicating.”

The researchers stated that the findings “indicate that the autophagy process plays an important role in resistance to certain types of pathogens,” specifically ones that can enter human cells.

“It’s known that as you get older you become more susceptible to infectious diseases and also that autophagy decreases,” said Levine. “In this paper, we’ve shown that signaling pathways that extend life and protect against bacterial invaders do so by triggering autophagy. This suggests that therapeutic strategies to increase autophagy may be effective in defeating harmful bacteria that can enter inside cells.”

The researchers explained that their next step is to see how an autophagy-inducing molecule helps to treat intracellular bacterial infections, such as salmonellosis, tuberculosis, tularemia and listeriosis. Other UT Southwestern researchers involved in the study include Dr. Kailiang Jia, lead author and instructor in internal medicine; Dr. Muhammad Akbar, clinical instructor in internal medicine; Dr. Qihua Sun, research scientist in internal medicine; Beverley Adams-Huet, assistant professor of clinical sciences; Dr. Christopher Gilpin, assistant professor of cell biology; and Dr. Collin Thomas, a former research associate in internal medicine.