Study shows HDL's parasite immunity qualities

Scientists have discovered how good cholesterol (HDLs) provide human immunity to certain parasites, which may serve as a platform for the assembly and delivery of two naturally occurring proteins that combine to create a super-toxic antimicrobial.

The scientists are confident that the research will provide key information to investigators seeking drug treatments for certain parasitic infections, such as malaria.

Such research is crucial to finding creating better treatments, and possibly cures, for diseases that are ravaging the people and economies of places like Africa and other developing countries.

The research focuses specifically on human innate immunity to Trypanosoma brucei brucei. The parasite is a close relative of Trypanosoma brucei gambienese and Trypanosoma brucei rhodesiense, the organisms that cause African sleeping sickness in humans.

The team, from the MBL's Global Infectious Diseases Program, found that two proteins work synergistically to kill the Nagana parasite in humans contradict a long-held hypothesis that a single protein was the key to HDL's parasite-fighting power.

To identify the proteins--known as apolipoprotein L-1 (apo L-1) and haptoglobin-related protein (Hpr)--MBL scientists tested different amounts and combinations of the proteins on Trypanosoma brucei brucei specimens.

To survive the parasite needs to digest the lipids in HDLs. Because HDL carries these proteins and enables them to combine, it is nature's perfect delivery system for the antimicrobial.

And when test organisms digested the super-toxic protein mix, the single-celled organisms literally dissolved.

Malaria, which rivals HIV/Aids as the world's most deadly infectious condition, is estimated to kill as many as 3 million people are every year and as many as 300 million cases are reported each year, mostly in tropical areas of South America, Africa and Asia.

Victims experience chills, fever and sweating. If left untreated, the parasite can cause kidney and liver failure, coma and death.

The complete paper can be found in the Journal of Biological Chemistry, Volume 280, Number 38.