Iron overloaded M0 macrophages regulate hematopoietic stem cell proliferation and senescence via the Nrf2/Keap1/HO-1
Lu Bai1, Fan Wang1, Hongmei Ouyang1
1Department of Clinical Laboratory, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan Province, 650032, China.
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.
Insights
Iron overload impairs macrophage function, negatively impacting hematopoietic stem cells (HSCs) proliferation and promoting senescence. Activating the Nrf2 pathway, however, can protect HSCs from these detrimental effects.
Area of Science:
- Hematology
- Cell Biology
- Immunology
Background:
- Iron overload is linked to hematological disorders, but its specific effects on hematopoietic stem cell (HSC) homeostasis are not fully understood.
- Macrophages play a crucial role in regulating HSC function and maintaining bone marrow microenvironment.
- The Nrf2/Keap1/HO-1 signaling pathway is a key regulator of cellular defense against oxidative stress.
Purpose of the Study:
- To investigate the impact of iron-overloaded macrophages on HSC proliferation and senescence.
- To explore the protective role of the Nrf2/Keap1/HO-1 signaling pathway in mitigating iron overload-induced damage to HSCs.
Main Methods:
- Established an iron overload model in THP-1 derived macrophages using ferric ammonium citrate (FAC).
- Assessed macrophage function by measuring phagocytic activity, reactive oxygen species (ROS), and inducible nitric oxide synthase (iNOS) expression.
- Utilized a co-culture system with HSCs to evaluate proliferation, cell cycle, and senescence markers, alongside Western blot analysis for oxidative stress and aging markers.
- Induced Nrf2 activation using 2-trifluoromethyl-2'-methoxychalcone (TMC) to assess its protective effects.
Main Results:
- Iron overload impaired macrophage function, characterized by reduced phagocytosis, increased ROS, and elevated iNOS.
- Iron-overloaded macrophages inhibited HSC proliferation, induced cell cycle arrest, and accelerated senescence, indicated by altered aging and proliferation markers (P16, SA-β-gal, HOXB4, RUNX1).
- Nrf2 activation via TMC treatment reversed these adverse effects, restoring HSC proliferation and reducing oxidative damage.
Conclusions:
- Iron-overloaded macrophages adversely affect HSCs homeostasis by impairing their function and promoting senescence.
- The Nrf2/Keap1/HO-1 signaling pathway plays a significant protective role against iron overload-induced HSC damage.
- Targeting the Nrf2 pathway may offer a therapeutic strategy for hematological disorders associated with iron overload.
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