Hyaluronan (HA) and serum-derived hyaluronan-associated protein (SHAP)-HA complex as predictive markers of cervical ripening in premature labor

Targeted Analysis of the Size Distribution of Heavy Chain-Modified Hyaluronan with Solid-State Nanopores

The glycosaminoglycan hyaluronan (HA) plays important roles in diverse physiological functions where the distribution of its molecular weight (MW) can influence its behavior and is known to change in response to disease conditions. During inflammation, HA undergoes a covalent modification in which heavy chain subunits of the inter-alpha-inhibitor family of proteins are transferred to its structure, forming heavy chain-HA (HC•HA) complexes. While limited assessments of HC•HA have been performed previously, determining the size distribution of its HA component remains a challenge. Here, we describe a selective method for extracting HC•HA from mixtures that yields material amenable to MW analysis with a solid-state nanopore sensor. After demonstrating the approach in vitro, we validate extraction of HC•HA from osteoarthritic human synovial fluid as a model complex biological matrix. Finally, we apply our technique to pathophysiology by measuring the size distributions of HC•HA and total HA in an equine model of synovitis.

Tumor necrosis factor-stimulated gene-6 (TSG-6) amplifies hyaluronan synthesis by airway smooth muscle cells

We tested the hypothesis that the artificial addition of heavy chains from inter-α-inhibitor to hyaluronan (HA), by adding recombinant TSG-6 (TNF-stimulated gene-6) to the culture medium of murine airway smooth muscle (MASM) cells, would enhance leukocyte binding to HA cables produced in response to poly(I:C). As predicted, the addition of heavy chains to HA cables enhanced leukocyte adhesion to these cables, but it also had several unexpected effects. (i) It produced thicker, more pronounced HA cables. (ii) It increased the accumulation of HA in the cell-associated matrix. (iii) It decreased the amount of HA in the conditioned medium. Importantly, these effects were observed only when TSG-6 was administered in the presence of poly(I:C), and TSG-6 did not exert any effect on its own. Increased HA synthesis occurred during active, poly(I:C)-induced HA synthesis and did not occur when TSG-6 was added after poly(I:C)-induced HA synthesis was complete. MASM cells derived from TSG-6(-/-), HAS1/3(-/-), and CD44(-/-) mice amplified HA synthesis in response to poly(I:C) + TSG-6 in a manner similar to WT MASM cells, demonstrating that they are expendable in this process. We conclude that TSG-6 increases the accumulation of HA in the cell-associated matrix, partially by preventing its dissolution from the cell-associated matrix into the conditioned medium, but primarily by inducing HA synthesis.

Airway smooth muscle cells synthesize hyaluronan cable structures independent of inter-alpha-inhibitor heavy chain attachment

The covalent association of inter-alpha-inhibitor-derived heavy chains (HCs) with hyaluronan was first described in synovial fluid from arthritic patients and later described as a structural and functional component of hyaluronan "cable" structures produced by many different cells and stimuli. HC transfer has been shown to be mediated by the protein product of TSG-6 (tumor necrosis factor-stimulated gene 6). Considering the accumulation of hyaluronan in airways following asthmatic attacks and the subsequent infiltration of leukocytes, we sought to characterize HC substitution of hyaluronan "cables" in primary mouse airway smooth muscle cells (MASM) and primary human airway smooth muscle cells (HASM). We found that cells derived from mice lacking TSG-6 had no defect in hyaluronan production or hyaluronan-mediated leukocyte adhesion when treated with the viral mimic poly(I,C). Functional hyaluronan cables were induced by cycloheximide in the confirmed absence of protein synthesis, with or without simultaneous treatment with poly(I,C). We characterized the species specificity of the antibody other investigators used to describe the HC-hyaluronan complex of hyaluronan cables and found minimal affinity to bovine-derived HCs in contrast to HCs from mouse and human sera. Thus, we cultured MASM and HASM cells in serum from these three sources and analyzed hyaluronan extracts for HCs and other hyaluronan-binding proteins, using parallel cumulus cell-oocyte complex (COC) extracts as positive controls. We conclude that, if hyaluronan cables derived from MASM and HASM cells are substituted with HCs, the amount of substitution is significantly below the limit of detection when compared with COC extracts of similar hyaluronan mass.