# From gut dysbiosis to decidual hostility: the immuno-metabolic crosstalk driving recurrent pregnancy loss

## TL;DR

This paper explores how gut health and immune metabolism contribute to unexplained recurrent pregnancy loss, proposing a new systemic model for understanding and treating the condition.

## Contribution

The paper introduces a novel integrative model linking gut dysbiosis, systemic metabolism, and decidual hostility in unexplained recurrent pregnancy loss.

## Key findings

- Gut dysbiosis may trigger systemic metabolic endotoxemia, reprogramming immune cells.
- Pre-sensitized immune cells in a hostile decidual environment lead to the collapse of maternal-fetal tolerance.
- The model suggests URPL is a systemic disease, not just a local issue, enabling new diagnostic and therapeutic strategies.

## Abstract

Recurrent pregnancy loss (RPL), particularly its unexplained form (URPL), represents a formidable challenge in reproductive medicine. Although traditionally attributed to local immune imbalances at the maternal-fetal interface, this perspective may not fully account for the condition’s upstream etiological drivers and recurrent nature. This review transcends this limitation by proposing and systematically substantiating an integrative ‘gut-systemic-decidual’ model of immunometabolic dysregulation. We posit that a key pathological cascade in many URPL cases may originate with distal gut dysbiosis, which, through imbalanced metabolite profiles and the leakage of inflammatory molecules such as lipopolysaccharide (LPS), triggers systemic ‘metabolic endotoxemia’ and fundamentally reprograms the metabolic state of circulating immune cells. This systemic ‘first hit’ is compounded when these ‘pre-sensitized’ cells migrate to an equally metabolically stressed and ‘hostile’ decidual microenvironment—a ‘second hit’ characterized by hypoxia and high lactate. This culminates in the functional collapse of the core sentinels of maternal-fetal tolerance, namely regulatory T (Treg) and decidual natural killer (dNK) cells, due to profound metabolic misprogramming. Ultimately, this integrated model elevates the etiological understanding of URPL from a ‘local conflict’ to that of a ‘systemic disease,’ paving the way for the development of dynamic warning systems that integrate multi-omics data and for the design of multi-level precision intervention strategies targeting patient stratification and preventive approaches for the gut, systemic metabolism, and the local microenvironment.