# Punicalagin Enhances Autophagy Through Sirtuin 1/FoxO3a Axis to Inhibit Intracellular Mycobacterium Abscessus Infection

## TL;DR

Punicalagin, a compound from pomegranates, helps fight Mycobacterium abscessus infection by boosting autophagy in macrophages, reducing bacterial load without directly killing the bacteria.

## Contribution

Punicalagin is shown to enhance antibacterial autophagy via the SIRT1/FoxO3a axis in macrophages, offering a novel host-directed therapy for M. abscessus.

## Key findings

- Punicalagin reduces intracellular MAB by 47% in THP-1 macrophages at 24 hours post-infection.
- Punicalagin promotes autophagy by upregulating SIRT1 and activating the SIRT1/FoxO3a axis, inhibiting the PI3K/Akt/mTOR pathway.
- In vivo, punicalagin reduces MAB burden in mouse lungs and decreases inflammatory cell infiltration.

## Abstract

Mycobacterium abscessus (MAB) is an increasingly recognized rapidly growing nontuberculous mycobacterial pathogen whose infection is particularly challenging to treat due to its antibiotic resistance and persistence, necessitating the exploration of innovative treatment strategies. In this study, it is demonstrated that punicalagin, a polyphenolic compound derived from pomegranate, enhances macrophage antibacterial activity by promoting autophagy rather than exerting direct bactericidal effects. In THP‐1 macrophages, punicalagin at 40 µm reduced intracellular MAB by 47% at 24 h post‐infection. Mechanistically, punicalagin treatment induced an increase LC3‐II/LC3‐I ratio and p62 degradation. It is found that punicalagin promotes autophagy by enhancing mitochondrial stability through upregulating SIRT1 and activating the SIRT1/FoxO3 axis, which in turn inhibits the PI3K/Akt/mTOR pathway. In vivo mouse studies show that punicalagin treatment significantly reduce the MAB burden in the lungs and alleviates the inflammatory cell infiltration in infected lung tissue. The investigation reveals a striking cellular selectivity in its mechanism of action. Punicalagin demonstrates preferential efficacy in interstitial macrophages, while exhibiting little impact on the MAB burden within alveolar macrophages. Transcriptomic analysis of sorted macrophage populations confirms a significant enrichment of autophagy and lysosome‐related pathways specifically in IMs from punicalagin‐treated mice. Taken together, the findings uncover a novel host‐directed therapeutic strategy against MAB infection.

Punicalagin, a pomegranate molecule, helps the body fight Mycobacterium abscessus. It preferentially boosts interstitial macrophages in the lung, stabilizing mitochondria and switching on the autophagy via SIRT1/FoxO3a, which lowers bacterial load without directly killing bacteria. The findings highlight a targeted, host‐directed strategy that complements existing treatments and may improve difficult‐to‐treat Mycobacterium abscessus infections.