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Effects of macrophage supernatants on mesangial cell migration and hillock formation
J Mattana1, S Jaffer, P C Singhal
1Department of Medicine, Long Island Jewish Medical Center, New Hyde Park, New York 11042.
Abstract:
There is considerable evidence suggesting a role for the macrophage (M phi) in the development of glomerulosclerosis (GS) and atherosclerosis, lesions which appear to be analogous. Migration of mesangial cells (MC), which are modified smooth muscle cells, may play a role in the pathogenesis of glomerular injury, and smooth muscle migration may play a role in the pathogenesis of atherosclerosis as well. We undertook the present study to determine the effects of M phi supernatants (M phi SN) on MC migration and formation of MC hillocks, which are considered an in vitro model of GS. By means of a migration assay using wounded cultures of confluent, growth-arrested MC, MC migration was found to be significantly enhanced by incubation with M phi SN at 24 hr (migration score: M phi SN, 24.3 +/- 1.3; control, 11.6 +/- 1.0, P < 0.001) as well as 48 hr incubation (migration score: M phi SN, 34.0 +/- 1.4; control, 15.4 +/- 1.4, P < 0.001). Enhanced MC migration following prolonged incubation with M phi SN was also shown using phase contrast microscopy and scanning electron microscopy. MC hillock formation was enhanced by M phi SN in a concentration-related manner as was hillock size. These data demonstrate that M phi SN can directly enhance MC migration and hillock formation, processes that may in part account for the observed role for the M phi in the development of mesangial expansion and GS as well as atherosclerosis.
Insights
Macrophage supernatants significantly enhance mesangial cell migration and hillock formation, key processes in glomerulosclerosis (GS) and atherosclerosis development.
Area of Science:
- Nephrology
- Immunology
- Cell Biology
Background:
- Macrophages (M phi) are implicated in glomerulosclerosis (GS) and atherosclerosis.
- Mesangial cell (MC) migration is a potential factor in glomerular injury and atherosclerosis pathogenesis.
Purpose of the Study:
- To investigate the effects of macrophage supernatants (M phi SN) on MC migration and the formation of MC hillocks.
- To determine if M phi SN can directly influence processes relevant to GS and atherosclerosis in vitro.
Main Methods:
- Utilized a migration assay with wounded, confluent, growth-arrested MC cultures.
- Incubated MC with M phi SN and measured migration using quantitative scores.
- Employed phase contrast and scanning electron microscopy to visualize MC behavior.
- Assessed MC hillock formation and size in response to varying concentrations of M phi SN.
Main Results:
- M phi SN significantly enhanced MC migration at both 24 and 48 hours compared to controls (P < 0.001).
- Microscopy confirmed enhanced MC migration with prolonged M phi SN incubation.
- MC hillock formation and size were increased by M phi SN in a concentration-dependent manner.
Conclusions:
- Macrophage supernatants directly promote MC migration and hillock formation.
- These findings suggest a direct mechanism by which macrophages contribute to mesangial expansion, GS, and atherosclerosis.