Related Experiment Video
Updated: Jun 2, 2026
In Vitro Phagocytosis of Myelin Debris by Bone Marrow-Derived Macrophages
Published on: December 30, 2017
Biochemical and morphological changes associated with macrophages and osteoclasts when challenged with infection -
Erin Callie Wiggers1, William Johnson, Michelle Tucci
1University of Mississippi Medical Center, Jackson, Mississippi.
Abstract:
Osteomyelitis is a bacterial infection of the bone that occurs frequently as a complication of open fractures and various kinds of orthopedic surgery. This infection can often lead to more extensive surgeries and even death of the patient. In animal models of osteomyelitis, the site of infection by Staphylococcus aureus was observed to have high numbers of both macrophages and osteoclasts, both of which may contribute to large amounts of osteolysis and tissue damage. In order to evaluate the immune response in both types of cells, two cells lines, a macrophage cell line and a macrophage cell line stimulated to become osteoclasts by the addition of receptor activator of nuclear-factor B (RANKL), were exposed to lipopolysaccharides, opsonized S. aureus, and unopsonized S. aureus. The results showed that both cell types activated a biochemical cascade that included the release of cytokines and nitric oxide associated with cell damage and death in response to infection. However, macrophages and osteoclasts differed in response magnitude, most likely due to differences in cell-membrane receptors. This data supports the growing body of research that links the immune and skeletal systems. Further understanding of biochemical pathways shared by the two systems could lead to significant advances in the treatment of osteomyelitis and the success of prostheses.
Insights
This study reveals that macrophages and osteoclasts, key immune cells, respond to Staphylococcus aureus bone infections by releasing damaging compounds. Their differing responses highlight the complex immune-skeletal system interaction in osteomyelitis.
Area of Science:
- Immunology
- Skeletal Biology
- Infectious Diseases
Background:
- Osteomyelitis is a severe bone infection often resulting from fractures or surgery.
- Staphylococcus aureus is a common pathogen in osteomyelitis, leading to significant tissue damage.
- Macrophages and osteoclasts are implicated in the bone destruction observed during osteomyelitis.
Purpose of the Study:
- To compare the immune responses of macrophages and osteoclasts to Staphylococcus aureus infection.
- To investigate the role of receptor activator of nuclear-factor B (RANKL) in osteoclast differentiation and response.
- To explore the biochemical pathways involved in immune cell-mediated bone damage.
Main Methods:
- Utilized macrophage cell lines and osteoclasts differentiated using RANKL.
- Exposed cells to lipopolysaccharides, opsonized, and unopsonized Staphylococcus aureus.
- Measured the release of cytokines and nitric oxide as indicators of cellular response and damage.
Main Results:
- Both macrophages and osteoclasts activated biochemical cascades, releasing cytokines and nitric oxide.
- Cellular responses were associated with tissue damage and cell death.
- Macrophages and osteoclasts exhibited differential response magnitudes, likely due to variations in cell-membrane receptors.
Conclusions:
- The immune response in osteomyelitis involves both macrophages and osteoclasts, contributing to bone damage.
- Differences in cell-membrane receptors influence the magnitude of immune cell responses.
- Understanding shared pathways between the immune and skeletal systems is crucial for advancing osteomyelitis treatment and prosthesis success.
Related Concept Videos
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...
01:40Cell-mediated Immune Responses
01:31Osteoclasts in Bone Remodeling