Accumulation of Ym1 and formation of intracellular crystalline bodies in alveolar macrophages lacking heparanase.
Heparanase is a heparan sulfate (HS) degrading endoglucuronidase that has been implicated in cell migration and inflammatory conditions. Here we used mice deficient of heparanase (Hpse(-/-)) to study the impact of heparanase on airway leukocytes. Normal numbers of macrophages and lymphocytes were present in bronchoalveolar lavage fluid of Hpse(-/-) mice, indicating that heparanase is not essential for proper homing of leukocytes to airways. While lymphocytes from Hpse(-/-) mice displayed normal morphology, Hpse(-/-) alveolar macrophages showed a striking, age-dependent appearance of granule-like structures in the cytoplasm. Transmission electron microscopy revealed that these structures corresponded to membrane-enclosed crystalline bodies that closely resembled the intracellular crystals known to be formed by the HS-binding protein Ym1, suggesting that heparanase deficiency is associated with intracellular Ym1 deposition. Indeed, applying immunocytochemistry, we found markedly higher levels of intracellular Ym1 protein in Hpse(-/-) versus WT alveolar macrophages, and there was a significant correlation between levels of Ym1 protein detected by immunoblotting and amounts of crystalline material in BAL cells. Biosynthetic radio-labeling of the macrophages revealed accumulation of non-degraded HS chains in Hpse(-/-) macrophages. Together, these findings implicate heparanase in normal processing of HS in macrophages, and indicate that heparanase regulates intracellular Ym1 accumulation and crystal formation in airways.
Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Sweden.
Ida
I
Waern
Juan
J
Jia
Gunnar
G
Pejler
Eyal
E
Zcharia
Israel
I
Vlodavsky
Jin-Ping
JP
Li
Sara
S
Wernersson
D000818:Animals; D002460:Cell Line; D048430:Cell Shape; D003459:Crystallins / Q000378:metabolism*; D005966:Glucuronidase / Q000172:deficiency / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D037102:Lectins / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism*; D000099175:Heparanase
D003459:Crystallins; D005966:Glucuronidase; D037102:Lectins; D001619:beta-N-Acetylhexosaminidases; D000099175:Heparanase; C429541:Chil3 protein, mouse