# Exosome-mediated bidirectional immune dysregulation in tuberculosis: proteomic profiling reveals strain-specific strategies of virulent H37Rv and attenuated H37Ra

## TL;DR

The study shows how tuberculosis bacteria use exosomes to manipulate the immune system differently depending on their strain, which could lead to new treatments.

## Contribution

The study reveals strain-specific immune modulation strategies of Mtb through exosome and macrophage proteomic profiling.

## Key findings

- RV maintains macrophage viability and proliferation, while RA induces apoptosis.
- RA-exosomes carry immunogenic antigens and trigger cytokine release, whereas RV-exosomes contain immunosuppressive effectors.
- Mtb uses exosomes as 'virulence vectors' to deliver signals that suppress immunity while promoting survival.

## Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a global health crisis, with drug resistance and immune evasion complicating control efforts. Mtb subverts macrophage function to establish persistent infection, but the role of exosomes in immune regulation remains poorly understood.

This study employed iTRAQ-based proteomics to dissect strain-specific immune modulation strategies of virulent H37Rv (RV) and attenuated H37Ra (RA) through macrophage and exosome profiling.

We revealed distinct survival strategies of Mtb in Macrophages: RV maintained host cell viability and intracellular proliferation, while RA induced apoptosis. Human proteomic profiling identified significantly more upregulated host proteins in RA-infected macrophages than in RV-infected cells, with RA robustly activating antigen presentation pathways. Conversely, exosomes from infected macrophages exhibited overall protein downregulation, particularly for RV. Strikingly, 24 of the top 25 enriched pathways were upregulated intracellularly but downregulated in exosomes, indicating bidirectional immune dysregulation. Bacterial proteomics revealed that functional proteins were preferentially sorted into exosomes. RV-exosomes were enriched in dormancy regulators (e.g., DevS) and immunosuppressive effectors, while RA-exosomes carried immunogenic antigens leading to robust cytokines releasing such as THF-a, IL-1a and IL-6.

Conclusively, Mtb exploits exosomes as “virulence vectors” to deliver RhoGDI and death signals (e.g., Caspse-9), paralyzing systemic immunity while optimizing intracellular survival. Virulence-specific cargo sorting informs novel diagnostics and therapies against TB. However, given the limitations of the in vitro model, future research should incorporate in vivo models and clinical trials to validate these findings.