# Bacterial Communities as Modulators of Innate Immune Signalling: An In Vitro Perspective on Toll‐Like Receptor Activation

## TL;DR

This study explores how bacteria in waste sorting plants can influence immune responses through TLR activation, highlighting the role of rare bacterial species.

## Contribution

The study reveals how specific bacterial species, even in low abundance, can significantly modulate innate immune signaling via TLR activation.

## Key findings

- Dominant bacterial species shape immune activation properties of the community.
- Rare bacterial taxa strongly influence TLR activation and immune responses.
- Bacterial contaminants in occupational settings may impact worker health through immune modulation.

## Abstract

Investigating the work‐environmental microbiome is critical for assessing occupational risk associated with exposure to microorganisms. The present study examined the bacterial composition of inhalable dust from waste sorting plants and explored their potential to induce Toll‐like receptors (TLR) in vitro, thereby providing insights into the immunomodulatory potential of complex microbial communities from occupational settings. These findings highlight how few dominant bacterial species shape the immune activation properties of the overall bacterial community, where less abundant taxa play a crucial role in immune modulation through TLR activation. The strong association between TLR activation and rare yet highly inductive bacterial taxa demonstrates their potential immunological significance, suggesting that even low‐abundant microbes may have a disproportionate impact on immune responses and occupational health outcomes.

Bacterial contaminants in occupational environments may elicit an immune response. This study investigated the immune‐modulatory potential of bacterial communities using in vitro cell‐based assays and revealed distinctive bacterial species as drivers of TLR2 and TLR4 activation. The presented approach studied the role of bacterial species as modulators of TLR‐mediated innate immune response and thereby contributed to a better understanding of the potential health implications of workers in modern waste management.