Glycosaminoglycan mimicry by COAM reduces melanoma growth through chemokine induction and function

Abstract

Chlorite-oxidized oxyamylose (COAM), a glycosaminoglycan mimetic and potent antiviral agent, provided significant growth reduction of syngeneic murine B16-F1 melanoma tumors. A single early dose (100 lg, into the site of tumor cell inoculation) was sufficient to establish a persistent effect over 17 days (resected tumor volume of 78.3 mm 3 in COAM-treated mice compared to 755.2 mm 3 in the control cohort, i.e., 89.6% reduction of tumor volumes). COAM was a much better antitumoral agent than the polyanionic glycosaminoglycan heparin. COAM retained its antitumoral effect in lymphopenic mice, reinforcing the idea of myeloid cell involvement. Massive recruitment of myeloid cells into dermal air pouches in response to COAM and their increased presence in early-treated tumors indicated that mainly CD11b 1 GR-1 1 myeloid cells were attracted by COAM to exert antitumoral effects. Leukocyte chemotaxis was mediated by the chemokine system through the induction in B16-F1 cells of mouse granulocyte chemotactic protein-2/CXCL6 upon COAM treatment. Thus, COAM constitutes a novel tool to study the role of innate immune cells in the initial stages of tumor development and an example that innate immunostimulating glycosaminoglycan mimicry may be exploited therapeutically.

Intradermal air pouch leukocytosis as an in vivo test for nanoparticles

“…Phosphate-buffered saline (PBS) was used as a negative control and chlorite-oxidized oxyamylose (COAM) as a positive control, for neutrophil recruitment. 38 After 24 hour contact, the exudates of the pouches were collected after injection of 1 mL pyrogen-free PBS containing heparin 20 U/mL and 2% fetal calf serum (FCS), and followed by 30 seconds of gentle massage. This procedure was repeated twice with 2 mL buffer, and the total exudate collection was centrifuged (10 minutes, 900 rpm).…”

“…We incubated 5 × 10 5 cells for 15 minutes with the Fc-receptor-blocking antibodies anti- and data were processed with the manufacturer's CellQuest software. 38 …”

Interference with Glycosaminoglycan-Chemokine Interactions with a Probe to Alter Leukocyte Recruitment and Inflammation In Vivo

“…Nothing was known about effects of COAM on the expression and binding to chemokines, other than GCP-2/CXCL6. Furthermore, whereas the effects of COAM on local injection are evident [16], [18], COAM may also exert effects on distant organs [17]. To study distant effects, we used here an animal model of LPS-induced recruitment of neutrophils to the liver and local neutrophil extracellular traps (NET) formation, and imaged in real time immunological events occurring upon COAM treatment with confocal intravital microscopy.…”

“…Poly(I:C) and heparan sulphate were purchased from Sigma-Aldrich (St. Louis, MO). Because many heparan sulphate preparations are heterogeneous and may vary from batch to batch, we used a heparan sulphate preparation with similar molecular characteristics as COAM, as detailed previously [18]. In addition, previously we also compared COAM with other glycosaminoglycans, including chondroitin sulphate and heparan sulphate preparations for binding to GCP-2/CXCL6 and demonstrated higher affinities for COAM than for both glycosaminoglycans [16].…”

“…), COAM induces the recruitment of neutrophils and macrophages that are in part essential to control viral burden and mortality upon acute infection with a neurotropic virus [16]. This effect of COAM, mediated by binding of GCP-2/CXCL6, illustrates that neutrophils contribute to antiviral resistance by the host, and can be further exploited to combat acute neuroinflammation [17], and cancer [18].…”