Lymph nodes-The neglected battlefield in tuberculosis

PLoS Pathog. 2020 Aug 13;16(8):e1008632. doi: 10.1371/journal.ppat.1008632. eCollection 2020 Aug.

Abstract

Lymph nodes, particularly thoracic lymph nodes, are among the most common sites of extrapulmonary tuberculosis (TB). However, Mycobacterium tuberculosis (Mtb) infection in these organs is understudied. Aside from being sites of initiation of the adaptive immune system, lymph nodes also serve as niches of Mtb growth and persistence. Mtb infection results in granuloma formation that disrupts and-if it becomes large enough-replaces the normal architecture of the lymph node that is vital to its function. In preclinical models, successful TB vaccines appear to prevent spread of Mtb from the lungs to the lymph nodes. Reactivation of latent TB can start in the lymph nodes resulting in dissemination of the bacteria to the lungs and other organs. Involvement of the lymph nodes may improve Bacille Calmette-Guerin (BCG) vaccine efficacy. Lastly, drug penetration to the lymph nodes is poor compared to blood, lung tissue, and lung granulomas. Future studies on evaluating the efficacy of vaccines and anti-TB drug treatments should include consideration of the effects on thoracic lymph nodes and not just the lungs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Humans
  • Lung / immunology*
  • Lung / microbiology
  • Lymph Nodes / immunology*
  • Lymph Nodes / microbiology
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / pathogenicity
  • Tuberculosis / immunology*
  • Tuberculosis / microbiology
  • Tuberculosis / pathology*
  • Tuberculosis / prevention & control
  • Tuberculosis Vaccines / immunology*

Substances

  • Tuberculosis Vaccines

Grants and funding

This study was funded by NIH grants AI123093 and AI114674, and the Bill and Melinda Gates Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.