RxPG News Feed for RxPG News

Medical Research Health Special Topics World
 Asian Health
 Food & Nutrition
 Men's Health
 Mental Health
 Occupational Health
 Public Health
 Sleep Hygiene
 Women's Health
 Canada Healthcare
 China Healthcare
 India Healthcare
 New Zealand
 South Africa
 World Healthcare
   Latest Research
 Alternative Medicine
 Clinical Trials
 Infectious Diseases
  Prion Diseases
  Small Pox
 Sports Medicine
   Medical News
 Awards & Prizes
   Special Topics
 Odd Medical News

Last Updated: Oct 11, 2012 - 10:22:56 PM
Research Article
PLoS Medicine
Tuberculosis Channel

subscribe to Tuberculosis newsletter
Latest Research : Infectious Diseases : Tuberculosis

   EMAIL   |   PRINT
DC-SIGN expressing alveolar macrophages are preferentially targeted by M. tuberculosis

Nov 15, 2005 - 7:21:00 PM
The authors propose a scenario where complement receptors mediate most of the initial infection of alveolar macrophages in a naïve host, and where once the infection is established DC-SIGN expressing alveolar macrophages become preferential target cells for M. tuberculosis.

[RxPG] C-type lectins are carbohydrate-binding cell surface molecules with a wide range of biological functions, many of which are related to immunity. Despite its name, dendritic cell specific intercellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) is not only expressed on dendritic cells but also on specialized macrophages in the placenta and lung. A number of pathogens are known to interact with DC-SIGN, and some (including HIV) seem to have evolved to derive advantages from these interactions.

Recent in vitro studies have shown that DC-SIGN can interact with Mycobacterium tuberculosis through a lipoglycan (a molecule composed of sugars and fatty acids) on the mycobacterial envelope called lipoarabinomannan (LAM). Trying to understand the role of DC-SIGN in tuberculosis (TB), Ludovic Tailleux and colleagues have focused on the interaction between M. tuberculosis and DC-SIGN–expressing cells in the lungs of human patients.

The researchers studied a total of 74 individuals, including 40 with TB, 11 with sarcoidosis, 14 with asthma, and nine control participants without active lung infection or inflammation. All patients underwent bronchoalveolar lavage (BAL), a procedure that yields cells and proteins from the lower respiratory tract. The researchers then examined BAL cell populations after staining for various cell-surface markers by flow cytometry, and found that, in individuals without TB, very few alveolar macrophages (an average of 3%) expressed DC-SIGN. In contrast, an average of 30% (and up to 70%) of macrophages from patients with TB expressed the lectin.

Tailleux and colleagues then incubated alveolar macrophages from a patient without TB ex vivo with M. tuberculosis, which resulted in infection of a subset of the cells. When the researchers examined DC-SIGN expression, they found that both infected and noninfected (bystander) cells in the population started to express DC-SIGN. The effect on bystander cells suggests that soluble factors from the microbe and/or the infected cells can induce DC-SIGN expression. Further functional ex vivo studies with cells from human patients indicated that DC-SIGN expression renders alveolar macrophages more susceptible to infection.

The authors propose a scenario where complement receptors mediate most of the initial infection of alveolar macrophages in a naïve host, and where—once the infection is established—DC-SIGN–expressing alveolar macrophages become preferential target cells for M. tuberculosis. Future work will be focused on identifying the soluble factors involved, and on determining whether DC-SIGN induction is an essential part of TB pathogenesis.

Publication: (2005) DC-SIGN and Lung Pathogenesis in Patients with Tuberculosis. PLoS Med 2(12): e410
On the web: Read Research Article (Open Access) at PLoS Medicine Journal Website 

Advertise in this space for $10 per month. Contact us today.

Related Tuberculosis News
PA-824 : Promising new drug for TB
Drug resistent TB deadlier, more common than suspected
Diabetes mellitus increases risk of TB
XDR TB in South Africa traced to lack of drug susceptibility testing
Vitamin D supplements may offer cheap and effective immune system boost against TB
Tuberculin skin tests not sensitive in detecting latent TB
Emergence of highly drug-resistant tuberculosis strains requires urgent action
Treating populations infected with HIV and latent TB could speed the emergence of drug-resistant TB
Solution to TB epidemic may lie in protective Heme oxygenase 1 protein
Explaining Why People of African Descent Are More Vulnerable to TB

Subscribe to Tuberculosis Newsletter

Enter your email address:

 Additional information about the news article
DOI: 10.1371/journal.pmed.0020410

Published: November 15, 2005

Copyright: © 2005 Public Library of Science. This is an open-access article distributed under the terms of the Creative Commons Attribution License. PLoS Medicine is an open-access journal published by the nonprofit organization Public Library of Science.
For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

Contact us

RxPG Online



    Full Text RSS

© All rights reserved by RxPG Medical Solutions Private Limited (India)