Macrophage state and Mycobacterium avium subsp. paratuberculosis persistence in cattle: An evidence-to-claim

Cleverson de Souza1

  • 1Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608, USA.

Insights

Johne's disease research reveals macrophages exhibit varied responses to Mycobacterium avium subsp. paratuberculosis (MAP) depending on disease stage. Current studies lack a uniform macrophage state atlas for MAP infection in cattle.

Area of Science:

  • Veterinary Immunology
  • Microbial Pathogenesis
  • Ruminant Infectious Diseases

Background:

  • Johne's disease, a chronic enteritis in ruminants, is caused by Mycobacterium avium subsp. paratuberculosis (MAP).
  • Macrophages are crucial intracellular hosts for MAP and key components of intestinal lesions in cattle.
  • Existing research presents inconsistent macrophage states due to variations in experimental design and methodology.

Purpose of the Study:

  • To systematically review and interpret MAP-macrophage interactions using a structured evidence-to-claim framework.
  • To assess the biological context, tested relationships, and resolved host/bacterial factors in MAP-macrophage research.
  • To evaluate bacterial endpoints and their alignment with study conclusions.

Main Methods:

  • Application of a novel evidence-to-claim framework to analyze existing MAP-macrophage literature.
  • Categorization of studies based on biological context, tested relationships, and resolved factors.
  • Assessment of bacterial endpoints including uptake, viable burden, trafficking, and shedding.

Main Results:

  • Evidence supports disease-history- and stage-dependent macrophage responsiveness to MAP.
  • A dissociation exists between inflammatory signaling and MAP control in specific models.
  • Altered lipid metabolism and phagosomal/endosomal dynamics, along with bacterial factors, influence intracellular MAP survival.

Conclusions:

  • A comprehensive macrophage-state atlas in natural bovine lesions is not yet established.
  • Durable innate tolerance or trained immunity in MAP-infected macrophages remains unproven.
  • Future research should pair defined macrophage phenotypes with robust bacterial fate endpoints in bovine models for stronger claims.

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