# Iron overloaded M0 macrophages regulate hematopoietic stem cell proliferation and senescence via the Nrf2/Keap1/HO-1 pathway

## TL;DR

This study shows how iron overload in macrophages harms hematopoietic stem cells and how activating a specific pathway can reverse this damage.

## Contribution

The study reveals a novel protective role of the Nrf2/Keap1/HO-1 pathway in mitigating iron overload effects on hematopoietic stem cells.

## Key findings

- Iron overload in macrophages impairs their function and negatively affects hematopoietic stem cell proliferation and senescence.
- Nrf2 activation reverses the harmful effects of iron overload on hematopoietic stem cells by reducing oxidative damage.
- The Nrf2/Keap1/HO-1 pathway plays a critical role in regulating hematopoietic stem cell homeostasis under iron overload conditions.

## Abstract

Numerous studies have established a link between iron overload and hematological disorders, yet its impact on hematopoietic stem cell (HSCs) homeostasis remains unclear. This study investigates the effects of iron-overloaded macrophages on HSCs proliferation and senescence, focusing on the potential protective role of the Nrf2/Keap1/HO-1 signaling pathway. In this experiment, THP-1 cells were first differentiated into M0 macrophages, which were then exposed to ferric ammonium citrate (FAC) to establish an iron overload model. The impact of iron overload on macrophage function was assessed by measuring phagocytic activity, reactive oxygen species (ROS) levels, and inducible nitric oxide synthase (iNOS) expression. A co-culture system with HSCs was used to evaluate the effects of iron-overloaded macrophages on HSCs proliferation, cell cycle progression, and senescence. Western blot analysis was employed to measure oxidative stress and aging markers. Nrf2 activation was induced to assess its protective role. The results showed that iron overload significantly impaired macrophage function, as evidenced by reduced phagocytic activity, increased ROS production, and elevated iNOS expression. In the co-culture system, iron-overloaded macrophages inhibited HSCs proliferation, induced cell cycle arrest, and accelerated senescence, as evidenced by increased aging markers (P16, SA-β-gal) and decreased proliferative markers (HOXB4, RUNX1). Nrf2 activation with 2-trifluoromethyl-2′-methoxychalcone (TMC) reversed these effects, restoring HSCs proliferation and reducing oxidative damage. In conclusion, this study explores how iron-overloaded macrophages affect HSCs through the Nrf2/Keap1/HO-1 pathway.