# Metabolomic profiling of host–pathogen interactions: differential effects of Gram-positive and Gram-negative bacterial secretomes on THP-1 macrophage metabolism

## TL;DR

This study uses metabolomics to compare how secretions from two types of bacteria affect the metabolism of immune cells, revealing both shared and unique effects.

## Contribution

The study identifies distinct and shared metabolic impacts of Gram-positive and Gram-negative bacterial secretomes on macrophages.

## Key findings

- Both bacterial secretomes modulate key metabolic pathways like alanine, aspartate, and glutamate metabolism.
- S. aureus caused asparagine and l-formylkynurenine accumulation and glycine depletion, while P. aeruginosa altered creatine and reduced asparagine and l-kynurenine.
- Both secretomes similarly affected arginine and proline metabolism in THP-1 macrophages.

## Abstract

Infectious diseases present substantial health and economic challenges worldwide. The increasing prevalence of multidrug-resistant bacteria in both community and hospital settings has emerged as a global health issue that necessitates innovative strategies for prompt diagnosis and treatment. Metabolomics, which provides comprehensive insights into the biochemical alterations of cellular phenotypes, has emerged as a valuable approach for studying host–pathogen interactions and identifying novel therapeutic targets. In this study, untargeted liquid chromatography-mass spectrometry (LC-MS)-based metabolite profiling was employed to investigate the differential effects of the secretome from Gram-positive S. aureus SH1000 and Gram-negative P. aeruginosa PAO1 on THP-1 macrophages. The results revealed that both bacterial secretomes modulate several key metabolic pathways, including alanine, aspartate and glutamate metabolism; sphingolipid metabolism; glycine and serine metabolism; glycolipid metabolism; and tryptophan metabolism. Distinct metabolic trends were observed between the two secretomes: S. aureus induced an accumulation of asparagine and l-formylkynurenine, alongside depletion of glycine-related intermediates (e.g. sarcosine, guanidinoacetate), whereas P. aeruginosa altered creatine levels and reduced asparagine and l-kynurenine. Notably, shared effects were also identified, with both secretomes demonstrating similar significant effects (FDR < 0.05 and VIP > 1) on arginine and proline metabolism in THP-1 macrophages. These findings highlight both shared and unique pathogen-specific metabolic responses, offering preliminary insights into host metabolic reprogramming triggered by exemplar Gram-positive and Gram-negative bacteria. These results provide a foundation for future studies to explore bacterial pathogenesis and to identify therapeutic strategies against resistant infections.

Treating THP-1 macrophages with S. aureus or P. aeruginosa secretome showed pronounced and distinctive metabolic disturbance.