An enzyme that normally repairs damaged DNA, may be the key to a new treatment for inflammatory diseases. Inflammatory diseases such as COPD and septicemia (blood poisoning) represent a growing threat to public health. Such conditions are commonly the result of an overactive immune system.
The discovery has been made by research scientists at the Karolinska Institute in Stockholm, Stockholm University, the University of Texas, and at NTNU and SINTEF in Trondheim, Norway. After a five-year research project, the results were published in the journal Science.
Key signal substance causes overactivity
Patients suffering from inflammatory diseases possess large amounts of a signal substance, known to biochemists as ROS. ROS is an abbreviation for "reactive oxygen species", which triggers inflammation and damages the genetic material, DNA, in our cells. "This damage is repaired by the enzyme OGG1.
Our research shows that this "repair" also acts as a trigger promoting overactivity in the immune systems of those patients suffering from auto-immune diseases, explains the Norwagian researcher Torkild Visnes at SINTEF.
"It may sound illogical, but in many diseases it is an overactive immune system that constitutes the problem" he says. This finding agrees with previous research showing that mice lacking the OGG1 enzyme are unable to activate a powerful immune response. As a result, these mice experience milder inflammation than normal mice.
Further development in the lab
Then began the laborious process of refining the substance so that it possessed all the properties needed to function in a living cell. Over a two-year period the research team made about a thousand variations on the basic substance and were finally left with the promising drug candidate TH5487, named simply as a result of being made after the variant TH5486.
TH5487 proved to have all of the three key properties that the researchers were looking for:
- It attached itself to the inflammation protein OGG1, inhibiting its activity and preventing it from bonding with DNA.
- It was able to deactivate OGG1 in living cells.
- It was very stable when injected into lab animals.
Healthier mice in Texas
The breakthrough came when researchers at the University of Texas tested the substance on mice suffering from serious cases of lung inflammation. TH5487 rapidly and effectively prevented the lung cells from activating inflammation genes.
As a result, immune cells were unable to register the developing infection and thus kept away from the lungs. Sensationally, the condition of the mice improved. The research team thus believe that they have discovered a new approach to suppressing inflammation that can be used instead of, or as a supplement to, existing treatments.
"The aim is to develop a drug that can work on people", says Visnes. "This will be a long journey because it is expensive and the regulations are complex. But we believe that we've now discovered a piece in the puzzle that may have major significance for the treatment of everything from auto-immune diseases to blood poisoning", he says.
cells, bacteria and other microscopic organisms use varying concentrations of chemicals in their environment—concentration gradients—to approach or avoid something in a process called chemotaxis. Egg cells release an attractant chemical, which lures the sperm. The researchers studied this action in Ascidia—sea squirts, brainless tubular creatures, which are only mobile as larvae.
"We identified that a calcium transport protein—plasma membrane Ca2+ ATPase (PMCA) – has a key role in sperm chemotaxis," says Yoshida. "PMCA is abundant in the tails or flagella membranes of the ascidian sperm. It binds to the species-specific attractant and alters how the flagella waves, thus directing movement of the sperm cell."
The team used a range of techniques to measure the effect they observed. These included a highly selective form of chromatography (separation of mixed compounds by diffusion in a fluid) called affinity column chromatography to isolate the attractant released by the egg; laser-based mass spectrometry, which uses lasers to identify what chemicals are in a sample; a quartz crystal microbalance, a sensitive microscopic weighing scale, to measure samples and how they change; and a high-speed camera to view sperm behavior in slow motion.
"With these methods we also found PMCA is responsible for regulating cellular calcium, whereas it was previously believed PMCA had no role in this," continues Yoshida. "Now we know PMCA plays an important part in cellular function. It makes it a promising target for drug research."