Cells of the body that are exposed to increased temperature, or other stressors such as invasion by microbes, respond by producing special proteins called heat shock proteins (Hsp). In general, these proteins can protect a cell during a stressful period, but scientists believe that they could also alert the host’s immune system to potential threats.
To test whether the rise in Hsp is intended as a cell-protective or a host-warning system, Graham Stewart and colleagues at Imperial College, London, investigated what happens when Mycobacterium tuberculosis, the organism that causes the respiratory disease tuberculosis (TB), infects a cell and the levels of Hsp rise (Nature Medicine, Vol. 7, No. 6, 01 Jun 2001).
They constructed a mutant strain of Mycobacterium tuberculosis that overexpressed a specific Hsp—Hsp70. Although this mutant bacterium was able to grow in vitro and able to infect a cell in the initial stages, it was unable to establish a chronic infection. Thus, the presence of excessive Hsp70 triggers the host’s immune system to keep the bacteria in check. The scientists propose that inducing Hsp might provide a novel strategy for reinforcement of host defenses of individuals infected with TB.
Dr. Graham R. Stewart
Departments of Infectious Diseases and Microbiology
Centre for Molecular Microbiology and Infection
Imperial College of Science, Technology and Medicine
Tel: +44 207-594-3964
Fax: +44 207-262-6299
(C) Nature Medicine press release.
Message posted by: Trevor M. D'Souza