Modelling the dynamics of tuberculosis lesions in a virtual lung: Role of the bronchial tree in endogenous reinfection

PLoS Comput Biol. 2020 May 20;16(5):e1007772. doi: 10.1371/journal.pcbi.1007772. eCollection 2020 May.

Abstract

Tuberculosis (TB) is an infectious disease that still causes more than 1.5 million deaths annually. The World Health Organization estimates that around 30% of the world's population is latently infected. However, the mechanisms responsible for 10% of this reserve (i.e., of the latently infected population) developing an active disease are not fully understood, yet. The dynamic hypothesis suggests that endogenous reinfection has an important role in maintaining latent infection. In order to examine this hypothesis for falsifiability, an agent-based model of growth, merging, and proliferation of TB lesions was implemented in a computational bronchial tree, built with an iterative algorithm for the generation of bronchial bifurcations and tubes applied inside a virtual 3D pulmonary surface. The computational model was fed and parameterized with computed tomography (CT) experimental data from 5 latently infected minipigs. First, we used CT images to reconstruct the virtual pulmonary surfaces where bronchial trees are built. Then, CT data about TB lesion' size and location to each minipig were used in the parameterization process. The model's outcome provides spatial and size distributions of TB lesions that successfully reproduced experimental data, thus reinforcing the role of the bronchial tree as the spatial structure triggering endogenous reinfection. A sensitivity analysis of the model shows that the final number of lesions is strongly related with the endogenous reinfection frequency and maximum growth rate of the lesions, while their mean diameter mainly depends on the spatial spreading of new lesions and the maximum radius. Finally, the model was used as an in silico experimental platform to explore the transition from latent infection to active disease, identifying two main triggering factors: a high inflammatory response and the combination of a moderate inflammatory response with a small breathing amplitude.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Antitubercular Agents / therapeutic use
  • Bronchi / metabolism*
  • Communicable Diseases / drug therapy
  • Computer Simulation
  • Female
  • Humans
  • Lung / microbiology
  • Lung / pathology
  • Models, Theoretical
  • Mycobacterium tuberculosis / growth & development*
  • Mycobacterium tuberculosis / metabolism
  • Mycobacterium tuberculosis / pathogenicity
  • Swine
  • Tomography, X-Ray Computed
  • Tuberculosis / drug therapy
  • Tuberculosis / pathology*
  • Tuberculosis, Pulmonary / drug therapy

Substances

  • Antitubercular Agents

Grants and funding

CP, PJC and MC received funding from “la Caixa” Foundation (ID 100010434), under agreement LCF/PR/GN17/50300003; CV, PJC, MM, JB, MT and RP received funding from Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR), Grup Unitat de Tuberculosi Experimental, 2017-SGR-500; CP, DL, SA, MC, JV received funding from Ministerio de Ciencia, Innovación y Universidades and FEDER, with the project PGC2018-095456-B-I00; CVM has a Miguel Servet II contract funded by the Instituto Carlos III (ISCIII, CPII18/00031). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.