Hyaluronan forms complexes with low density lipoprotein while also inducing foam cell infiltration in the dermis.

BACKGROUND: Xanthoma is a foam cell infiltrating lesion similar to atherosclerosis. Glycosaminoglycans and proteoglycans have long been considered to play a role in atherogenesis. OBJECTIVE: The purpose of this study is to investigate the role of hyaluronan, the main dermal glycosaminoglycan, in xanthoma formation. METHODS: The complex formation of low density lipoprotein (LDL) with hyaluronan was investigated by assaying the cholesterol level of precipitates that were formed by incubating LDL, hyaluronan and cetylpyridinium chloride in the presence of Ca2+. The uptake of LDL by mouse peritoneal macrophages was studied by assaying the cellular cholesterol esterification activity. The responsible receptor for the LDL internalization was examined by saturating hyaluronan receptor and blocking class A macrophage scavenger receptor (CD204). Hyaluronan was injected into the dorsal skin of diet-induced hypercholesterolemic rabbits to reveal the xanthoma inducing activity of hyaluronan. RESULTS: Cetylpyridinium chloride precipitated hyaluronan, which had formed complexes with LDL. The macrophages incorporated hyaluronan-LDL complexes and oxidized LDL via CD204. Foam cell infiltration and cholesterol accumulation were induced by intradermal injections of hyaluronan in diet-induced hypercholesterolemic rabbits. CONCLUSION: Hyaluronan, like other sulfated glycosaminoglycans, retains LDL by forming a complex. Via macrophage scavenger receptors, macrophages incorporate not only LDL-hyaluronan complexes, but also oxidized LDL, which has been oxidized during the retention time.

Neuronal conditions of spinal cord in dermatitis are improved by olopatadine.

Intense pruritus and cutaneous reactivity represent cardinal features of eczema. The resulting scratching behaviors alter neuronal conditions of the spinal dorsal horn where the primary sensory afferent fibers transmit cutaneous stimulation and deteriorate eczematous skin lesions. We investigated the effects of olopatadine hydrochloride (olopatadine) on alteration of neuronal conditions of the spinal dorsal horn and eczematous skin lesions induced by contact dermatitis. Eczematous lesions were induced by repeated application of diphenylcyclopropenone (DCP) in BALB/c mice. Olopatadine suppressed scratching behavior caused by repeated application of DCP in mice. Increased expressions of c-Fos and substance P in the spinal dorsal horn following DCP application were improved by olopatadine. Furthermore, olopatadine diminished the number of infiltrating cells and levels of cytokines in eczematous skin lesions resulting from DCP application. Olopatadine improves neurological conditions in the spinal cord and eczematous skin lesions in a murine contact dermatitis model.

Perlecan regulates bidirectional Wnt signaling at the Drosophila neuromuscular junction.

Heparan sulfate proteoglycans (HSPGs) play pivotal roles in the regulation of Wnt signaling activity in several tissues. At the Drosophila melanogaster neuromuscular junction (NMJ), Wnt/Wingless (Wg) regulates the formation of both pre- and postsynaptic structures; however, the mechanism balancing such bidirectional signaling remains elusive. In this paper, we demonstrate that mutations in the gene of a secreted HSPG, perlecan/trol, resulted in diverse postsynaptic defects and overproduction of synaptic boutons at NMJ. The postsynaptic defects, such as reduction in subsynaptic reticulum (SSR), were rescued by the postsynaptic activation of the Frizzled nuclear import Wg pathway. In contrast, overproduction of synaptic boutons was suppressed by the presynaptic down-regulation of the canonical Wg pathway. We also show that Trol was localized in the SSR and promoted postsynaptic accumulation of extracellular Wg proteins. These results suggest that Trol bidirectionally regulates both pre- and postsynaptic activities of Wg by precisely distributing Wg at the NMJ.

Alteration of sensorineural circuits in spinal cord by chronic contact dermatitis.

In the present study, eczema-induced alteration of sensorineural circuits of the spinal dorsal horn was investigated. Eczematous lesions resembling atopic dermatitis were induced by repeated application of diphenylcyclopropenone (DCP) onto murine right hind paws. Immunohistochemical labeling of calcitonin gene-related peptide and substance P was increased in the dorsal horn on the DCP-treated side. Expression of calcium binding proteins, calretinin and calbindin-D28K, normally widely seen in dorsal horn interneurons, was up-regulated on the DCP-treated side. E-Cadherin and alpha-N-catenin, synapse-related molecules, were intensely expressed in the spinal dorsal horn of the DCP-treated side. Interestingly, c-Fos positive cells were also significantly increased in laminae I and III of the DCP-treated side. These results suggest an enhanced release of neuropeptides from peripheral afferents and alterations in the sensorineural circuitry of the dorsal horn. These changes may account for the enhanced sensory sensitivity recognized in patients with chronic eczema and atopic dermatitis.