Pronociceptive Roles of Schwann Cell-Derived Galectin-3 in Taxane-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe dose-limiting side effect of taxanes such as paclitaxel and docetaxel. Despite the high medical needs, insufficient understanding of the complex mechanism underlying CIPN pathogenesis precludes any endorsed causal therapy to prevent or relieve CIPN. In this study, we report that elevation of plasma galectin-3 level is a pathologic change common to both patients with taxane-treated breast cancer with CIPN and a mouse model of taxane-related CIPN. Following multiple intraperitoneal injections of paclitaxel in mice, galectin-3 levels were elevated in Schwann cells within the sciatic nerve but not in other peripheral organs or cells expressing galectin-3. Consistent with this, paclitaxel treatment of primary cultures of rat Schwann cells induced upregulation and secretion of galectin-3. In vitro migration assays revealed that recombinant galectin-3 induced a chemotactic response of the murine macrophage cell line RAW 264.7. In addition, perineural administration of galectin-3 to the sciatic nerve of naive mice mimicked paclitaxel-induced macrophage infiltration and mechanical hypersensitivity. By contrast, chemical depletion of macrophages by clodronate liposomes suppressed paclitaxel-induced mechanical hypersensitivity despite the higher level of plasma galectin-3. Deficiency (Galectin-3 ^-/- mice) or pharmacologic inhibition of galectin-3 inhibited paclitaxel-induced macrophage infiltration and mechanical hypersensitivity. In conclusion, we propose that Schwann cell-derived galectin-3 plays a pronociceptive role via macrophage infiltration in the pathogenesis of taxane-induced peripheral neuropathy. Therapies targeting this phenomenon, which is common to patients with CIPN and mouse models, represent a novel approach to suppress taxane-related CIPN. SIGNIFICANCE: These findings demonstrate that the elevation of plasma galectin-3 is a CIPN-related pathologic change common to humans and mice, and that targeting galectin-3 is a therapeutic option to delay CIPN progression.

[Clinical usefulness of serum total cholesterol as an index of hypothyroidism in patients after cervical radiation]

Cervical radiation therapy is often applied to patients with head and neck cancers because radiation has a high sensitivity to these cancers and permits the preservation of functions and physical form. However, it has been shown that various complications can result from radiation therapy. We have encountered some patients who showed hypercholesterolemia resulting from cervical radiation. Therefore, we have paid close attention to the relationship between hypercholesterolemia after cervical radiation and hypothyroidism. Thyroid hormone tests in these patients with hypercholesterolemia after cervical radiation showed high thyroid stimulating hormone (TSH) and low free thyroxine (fT4), indicating the presence of hypothyroidism. After administration of levothyroxine Na, their fT4 levels increased and both TSH levels and serum total cholesterol levels decreased. In conclusion, in patients who have received cervical radiation, we recommend monitoring serum total cholesterol periodically to detect hypothyroidism easily before the appearance of its symptoms.