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CD44 positive macrophages take up hyaluronan during lung development
C B Underhill1, H A Nguyen, M Shizari
1Department of Anatomy and Cell Biology, Georgetown Medical Center, Washington, DC 20007.
Developmental Biology
|February 1, 1993
Summary
During mouse lung development, hyaluronan decreases while its receptor CD44 increases, particularly on macrophages. Macrophages appear to internalize hyaluronan, aiding its removal from lung tissue.
Area of Science:
- Developmental Biology
- Extracellular Matrix Biology
- Immunology
Background:
- Hyaluronan (HA) and its receptor CD44 play roles in tissue development and remodeling.
- Understanding their dynamic interplay during lung development is crucial.
Purpose of the Study:
- To investigate the expression and distribution of hyaluronan and CD44 during mouse lung development.
- To elucidate the functional relationship between hyaluronan and CD44-expressing cells, particularly macrophages.
Main Methods:
- Enzyme-linked assays using a biotinylated proteoglycan/link protein probe (b-PG) to quantify hyaluronan.
- Histochemical staining with b-PG and a CD44-specific antibody (KM-201) on embryonic and adult mouse lungs.
- In vivo experiments involving CD44 antibody injection in newborn mice.
Main Results:
- Hyaluronan levels decreased with lung development, shifting from interstitial to perivascular/peribronchiolar distribution.
- CD44 expression increased with development, primarily on macrophages, bronchial/bronchiolar epithelium, vascular smooth muscle, and endothelial cells.
- Macrophages showed increased CD44 expression correlating with decreased hyaluronan and contained intracellular hyaluronan, suggesting internalization.
Conclusions:
- Macrophages actively internalize hyaluronan during mouse lung development.
- Macrophages may play a significant role in clearing hyaluronan from the developing lung extracellular matrix.
- The dynamic regulation of hyaluronan and CD44 is critical for lung morphogenesis.