Related Experiment Video
Updated: Jun 19, 2025
Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation
Published on: April 29, 2015
Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages
Chen Cheng1, Zhiyao Xing1, Wenxin Zhang1
1State Key Laboratory of Pharmaceutical Biotechnology, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing 210093, People's Republic of China.
Abstract:
Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.
Insights
Iron regulatory protein 2 (IRP2) deficiency impairs macrophage lysosomal function, increasing susceptibility to liver abscesses during intestinal inflammation. Restoring TFEB function protects against bacterial infections in Crohn's disease models.
Area of Science:
- Immunology
- Gastroenterology
- Molecular Biology
Background:
- Pyogenic liver abscesses are a complication in patients with colorectal cancer and Crohn's disease, linked to impaired bacterial clearance by immune cells.
- Iron regulatory protein 2 (IRP2) plays a role in cellular iron homeostasis, but its specific function in immune responses during intestinal inflammation is not fully understood.
Purpose of the Study:
- To investigate the role of IRP2 in protecting against liver abscesses during intestinal inflammation.
- To elucidate the molecular mechanisms by which IRP2 influences macrophage function and bacterial clearance.
Main Methods:
- Utilized global and myeloid cell-specific IRP2-deficient mouse models subjected to dextran sodium sulfate-induced intestinal injury.
- Assessed lysosomal acidification, biogenesis, and bacterial clearance in liver tissues and macrophages.
- Investigated the localization of transcription factor EB (Tfeb) and its downstream gene expression.
- Examined clinical samples from Crohn's disease patients and utilized bioinformatic analysis of inflammatory bowel disease patient databases.
Main Results:
- IRP2 deficiency led to increased susceptibility to liver abscesses in mice with intestinal injury.
- IRP2 is essential for lysosomal acidification and biogenesis, critical for bacterial clearance.
- IRP2 deficiency resulted in reduced nuclear translocation of Tfeb, downregulating lysosomal biogenesis genes.
- Tfeb mislocalization was reversible by inhibiting hypoxia-inducible factor 2 or lactic acid production.
- Clinical data from Crohn's disease patients and bioinformatic analyses confirmed reduced IRP2 and TFEB-dependent lysosomal gene expression.
Conclusions:
- IRP2 is crucial for maintaining macrophage lysosomal function and antimicrobial activity during intestinal inflammation.
- IRP2 facilitates Tfeb nuclear translocation, thereby promoting lysosomal biogenesis and bacterial clearance.
- Dysregulation of the IRP2-Tfeb-lysosome axis contributes to liver abscess susceptibility in inflammatory bowel diseases.
Related Concept Videos
01:23Antimicrobial Proteins
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
01:31Regulation of the Unfolded Protein Response
01:25Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
01:23Types of RNA
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
01:31Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
01:40Cell-mediated Immune Responses