Related Experiment Video
Updated: Oct 26, 2025
Proteomic Analysis of Human Macrophage Polarization Under a Low Oxygen Environment
Published on: January 7, 2019
The regulation of macrophage polarization by hypoxia-PADI4 coordination in Rheumatoid arthritis
Yu Cheng1, Yuying Si1, Lan Wang1
1Department of Clinical Laboratory, Shanghai East Hospital, 150 Ji Mo Road, Shanghai 200120, People's Republic of China.
Background:
Hypoxia, a common feature of rheumatoid arthritis (RA), induces the over-expression of peptidyl arginine deiminase 4 (PADI4) in fibroblast-like synoviocytes (FLSs) and macrophages. However, the roles of PADI4 and its inducer hypoxia in the regulation of macrophage polarization remain unclear. This study aimed to investigate the role of hypoxia-PADI4 for macrophage polarization in RA patients.
Methods:
Synovial tissue (ST) and synovial fluid (SF) were collected from 3 OA patients and 6 RA patients. The distribution of M1 and M2 in ST and cytokines in SF were examined by immunohistochemical analysis and Bio-Plex immunoassays. THP-1 macrophages and BMDM polarization were determined under normoxic (21% oxygen) or hypoxic (3% oxygen) conditions. The effects of PADI4 on macrophages were determined by transfection of adenovirus vector-coated PADI4 (AdPADI4) and the use of PADI4 inhibitor. Finally, the roles of PADI4 in joint synovial lesions on macrophage polarization were investigated in collagen-induced arthritis (CIA) rats.
Results:
We found increased macrophage polarization of M1 and M2 in the RA ST, compared with OA ST. The ratio of M1/M2 for RA and OA was 1.633 ± 0.1443 and 2.544 ± 0.4429, respectively. The concentration of M1- and M2-type cytokines was higher in RA than that in OA patients. Hypoxia contributed to the increase of the gene and protein expression of M1 and M2 markers. M1- but not M2-type gene expression showed a positive relationship with PADI4 expressionwhile the level of expression of M2-type genes showed no significant difference. The degree of joint swelling and destruction was effectively alleviated, and the number of macrophages especially M1 decreased in CIA rats after down-regulating PADI4 expression.
Conclusion:
Hypoxia is responsible for the co-polarization of M1 and M2. Hypoxia-associated PADI4 is responsible for M1 macrophage activation, implying that the inflammatory environment can be eased by decreasing PADI4 expression and improving the hypoxic environment.
Insights
Hypoxia and peptidyl arginine deiminase 4 (PADI4) drive M1 macrophage activation in rheumatoid arthritis (RA). Targeting PADI4 and improving the hypoxic environment may ease RA inflammation.
Area of Science:
- Immunology
- Rheumatology
- Cell Biology
Background:
- Rheumatoid arthritis (RA) is characterized by hypoxia, which upregulates peptidyl arginine deiminase 4 (PADI4) in synovial cells.
- The precise roles of hypoxia and PADI4 in regulating macrophage polarization in RA remain incompletely understood.
Purpose of the Study:
- To investigate the influence of hypoxia and PADI4 on macrophage polarization in rheumatoid arthritis patients.
- To explore the therapeutic potential of targeting PADI4 and hypoxia in RA.
Main Methods:
- Analysis of synovial tissue and fluid from osteoarthritis (OA) and RA patients.
- In vitro studies using THP-1 macrophages and bone marrow-derived macrophages (BMDMs) under normoxic and hypoxic conditions.
- In vivo studies in collagen-induced arthritis (CIA) rat models with PADI4 modulation.
Main Results:
- RA synovial tissue exhibits increased M1 and M2 macrophage polarization compared to OA.
- Hypoxia promotes the expression of both M1 and M2 macrophage markers.
- PADI4 expression positively correlates with M1 macrophage markers, and its downregulation alleviates joint inflammation in CIA rats.
Conclusions:
- Hypoxia induces co-polarization of M1 and M2 macrophages in RA.
- Hypoxia-associated PADI4 is a key driver of M1 macrophage activation in RA.
- Reducing PADI4 expression and ameliorating hypoxia could be effective strategies for managing RA-associated inflammation.
More Related Videos
Related Concept Videos
01:24T Cell Types and Functions
Th1 cells stimulate dendritic cells to express necessary co-stimulatory molecules on their surfaces for...
01:20The JAK-STAT Signaling Pathway
01:28Inflammatory Response
Inflammation can be triggered by various stimuli, such as impact, abrasion, chemical irritation, infections, and extreme hot or cold temperatures. These can damage cells and connective tissue fibers,...
01:24Regulation of Angiogenesis and Blood Supply
01:38Inflammation