Modification of Hyaluronan by Heavy Chains of Inter-α-Inhibitor in Idiopathic Pulmonary Arterial Hypertension

Abstract

We previously reported an altered hyaluronan (HA) metabolism in idiopathic pulmonary arterial hypertension (IPAH) lung tissue and cultured smooth muscle cells. Hyaluronan was present in the smooth muscle cell layer surrounding the pulmonary vasculature and in plexigenic lesions. Additionally, cultured pulmonary artery smooth muscle cells produced spontaneous HA "cable" structures, without additional stimuli, that were leukocyte-adhesive. We now present evidence that the HA that accumulates in IPAH plexigenic lesions is a pathological form of HA in which heavy chains (HCs) from the serum-derived proteoglycan inter-α-inhibitor are covalently attached to the HA backbone to form a pathological HC-HA complex. CD45-positive leukocytes were identified within these HC-HA matrices. Elevated mRNA levels of the enzyme that transfers HCs to HA, known as tumor necrosis factor-stimulated gene 6, were detected in IPAH lung tissue.

Hyaluronidase and Hyaluronan Oligosaccharides Promote Neurological Recovery after Intraventricular Hemorrhage

“…HA contents in rabbit brain slice were measured as described previously (Lauer et al, 2009). Briefly, forebrain slices taken at the level of the midseptal nucleus were digested with proteinase K, and HA was recovered by ethanol precipitation.…”

“…from rabbit brains by proteinase K digestion, was quantified by ELISAlike assay, as described previously (Haserodt et al, 2011). Agarose gel electrophoresis was performed on 2 mm coronal slices taken from the forebrain at the level of the midseptal nucleus, based on a previous description (Lauer et al, 2009).…”

“…The samples were then lyophilized to dryness, labeled with 2-aminoacridone, and incubated overnight at 37°C. The samples were analyzed by electrophoresis and the bands quantified using Image J software, as described previously (Lauer et al, 2013a).…”

“…However, transfer of HC to HA oligosaccharides (8 -21 oligosaccharide units) is an irreversible event. We have demonstrated the utility of this observation by irreversibly swapping HCs from HC-HA onto a HA oligosaccharide in the synovial fluid of patients with rheumatoid arthritis, thereby restoring the pathological HC-HA matrices to their normal state (Lauer et al, 2013b). Accordingly, aliquots of homogenates made from GEs of infants with IVH were incubated at 37°C with HA10 (10 monosaccharide units) for 24 or 72 h. Adding exogenous recombinant TSG-6 resulted in a smear above 250 kDa (Fig.…”

“…HC-HA complexes exhibit proinflammatory activity by promoting adhesion of leukocytes to HA matrices and by extravasation of leukocytes into the interstitial spaces (Zhuo et al, 2006). HA oligosaccharides of 8 -21 monosaccharides (ϳ1.5 kDa) have been used to remove the HCs from HC-HA complexes, thereby reducing the concentration of pathological HC-HA (Lauer et al, 2013b). HA oligosaccharides also impede HA-CD44 interaction by inducing CD44 receptor cleavage and by competitive binding to CD44 (Sugahara et al, 2003;Teriete et al, 2004).…”