Biochemical Characterization of Endogenously Formed Eosinophilic Crystals in the Lungs of Mice

Abstract

Crystals seldom form spontaneously within tissues of mammals, except in the urinary tract or in association with eosinophil-rich diseases in humans (Charcot-Leyden crystals). Endogenously formed eosinophilic crystals have been reported in respiratory tract and other tissues of several strains of mice, but the biochemical characterization of these crystals has not been reported. In this study, eosinophilic crystal formation was examined in homozygous C57BL/6J viable motheaten mice, lung-specific surfactant apoprotein C promoter/soluble human tumor necrosis factor p75 receptor type II fusion protein transgenic mice (C57BL/6NTac ؋ Sv/129), and CD40L-deficient mice with spontaneous Pneumocystis carinii infection. In viable motheaten but not wild type mice, rapidly developing crystals represented a major feature of the fatal lung injury induced by macrophage dysregulation. Conversely, eosinophilic crystals did not form until 4 -8 months of age in transgenic and CD40L-deficient mice and were present in 10 -30% of agematched wild type controls. Mass spectrometry analysis of proteins from bronchoalveolar lavage fluid identified the crystals as Ym1, sometimes referred to as T-lymphocyte-derived eosinophil chemotactic factor. The Ym1 sequence was homologous to chitinase, and enzymatic assays indicated a 3-5-fold increase in chitinase activity compared with control mice. Intracellular and extracellular crystals associated with epithelial damage suggested that the crystals may contribute to lung inflammation through mechanical damage and enzymatic degradation.

Accumulation of Ym1 and formation of intracellular crystalline bodies in alveolar macrophages lacking heparanase

“…This would be in some analogy with the proposed contribution of HSPGs to amyloid formation (Stevens and Kisilevsky, 2000). (Chang et al, 2001) and intracellular crystalline bodies in vivo (Nio et al, 2004), in particular in alveolar macrophages from aged immunodeficient mice (Guo et al, 2000;Harbord et al, 2002). Secondly, since HS and heparin are physiological ligands to Ym1 (Chang et al, 2001), it may be speculated that changes in HS turnover affect Ym1 aggregation and crystallization.…”

“…The physiological function of Ym1 is not clear, but a role in eosinophil chemotaxis (Owhashi et al, 2000) and promotion of cytokine production (Cai et al, 2009) has been suggested. Interestingly, Ym1 has been reported to exhibit a weak ability to cleave Nacetylglucosamine units (Guo et al, 2000;Harbord et al, 2002), suggesting that Ym1 may not only bind to HS but can possibly also cleave HS, and thus function in a manner similar to heparanase. However, the ability of Ym1 to process HS remains to be established.…”

Src homology 2 domain–containing inositol 5-phosphatase 1 deficiency leads to a spontaneous allergic inflammation in the murine lung

“…16 Total histamine and spontaneously released histamine levels were determined by using single-cell suspensions from spleens and lungs, as previously described 17 and in as described detail in the Methods section in the Online repository at www.jacionline.org.…”

Human YKL-39 is a pseudo-chitinase with retained chitooligosaccharide-binding properties

“…These include YKL-40 (chitinase 3-like-1), YKL-39 (chitinase 3-like-2), Ym1/2 (chitinase 3-like-3/4), oviduct-specific glycoprotein and stabilin-1-interacting chitinaselike protein [11][12][13][14][15][16][17]. YKL-40 (also termed HC-gp39 or Chi3l1) was found to be secreted, along with chitotriosidase, from activated human macrophages and it was later detected in the culture supernatant of chondrocytes, synovial cells and osteoblasts [2,11].…”