# Anti-Chlamydia trachomatis Host Defence Arsenal Within the Cervicovaginal Environment

## TL;DR

This review explores how the cervicovaginal environment defends against Chlamydia trachomatis infections and how the bacteria counteract these defenses.

## Contribution

The paper provides a comprehensive overview of host defense mechanisms and bacterial evasion strategies in the cervicovaginal environment.

## Key findings

- Lactobacillus crispatus and molecules like lactoferrin protect against Chlamydia through coaggregation and anti-inflammatory activity.
- Interferon-gamma (IFN-γ) is crucial for clearing infections by depleting nutrients and destroying bacterial inclusions.

## Abstract

Chlamydia trachomatis has a significant impact on public health, especially among adolescents and young women; it primarily affects urogenital epithelial cells, leading to cervicitis and urethritis, with >90% of cases showing no symptoms. Consequently, chlamydial infections are commonly misdiagnosed, and, if untreated, they may result in severe reproductive sequelae including infertility. A better understanding of C. trachomatis cell biology and bacterial–host cell interactions may be helpful to identify strategies able to counter its transmission among the population, as well as its dissemination in reproductive tissues, reducing the risk of developing severe reproductive sequelae. Therefore, the present review aims to summarize the evidence on the interplay between C. trachomatis and the host defence factors within the cervicovaginal environment. The sophisticated strategies employed by this clinically significant pathogen to counteract these mechanisms are also discussed. In the literature, the main defence factors include the microbiota dominated by Lactobacillus crispatus and several molecules like lactoferrin, able to protect the cervicovaginal microenvironment against C. trachomatis through several mechanisms (e.g., EB coaggregation and competitive exclusion, as well as anti-inflammatory activity). However, the major player in clearing chlamydial infections remains the interferon-gamma (IFN-γ) produced by natural killer and T cells, via the depletion of critical nutrients for C. trachomatis such as tryptophan, or via the ubiquitylation and destruction of chlamydial inclusions.