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.
Waern
Ida
I
Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Sweden.
Jia
Juan
J
Pejler
Gunnar
G
Zcharia
Eyal
E
Vlodavsky
Israel
I
Li
Jin-Ping
JP
Wernersson
Sara
S
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