(a) Total cell lysates of spinal cord immune cells enriched with Percoll centrifugation were subjected to immunoblotting with the anti-KS antibody. expression was abolished. Concomitantly, pro-inflammatory cytokines, i.e., interferon (IFN)-, interleukin (IL)-1, and tumor necrosis factor (TNF)-, were increased in the spinal cord of EAN rats, whereas anti-inflammatory cytokines, such as IL-4 and IL-10, were decreased. In addition, silencing of KSGal6ST attenuated KS expression on the primary cultured microglia and upregulated expression of some activation markers (TNF-, IL-1, and iNOS) under the stimulation with lipopolysaccharide and IFN-. This study demonstrates for the first time a close association of EAN and disappearance of KS on microglia. KS expression could be a useful marker to evaluate the status of polyneuropathy. Keywords:experimental autoimmune neuritis, keratan sulfate, microglia Experimental autoimmune neuritis (EAN) is an animal model of human GuillainBarr syndrome, and is a helper T-cell-mediated inflammatory demyelination disease in peripheral nerve that is affected by the immunization of P2 peptide.1,2,3The pathology of peripheral nerves in EAN has been extensively studied; EAN involves disruption of blood nerve barrier, infiltration of T cells and macrophages, leakage of immunoglobulin, and regional demyelination.4,5,6Although the central nervous system (CNS) has been poorly studied on EAN, some important findings on CNS have been reported. Microglia transiently increase in number and they express P2X4 receptor involved in allodynia and pain hypersensitivity in the dorsal horn of the spinal cord in EAN.7,8Moreover, infiltration of CD4-positive T cells is observed in the spinal cord and triggers apoptosis of motor neurons.9 Proteoglycans (PGs) have long sugar chains, so-called glycosaminoglycans, i.e., chondroitin sulfate, keratan sulfate (KS), dermatan Rabbit Polyclonal to CST11 sulfate, and heparan sulfate.10,11KS is a polymer of lactosamine, 3Gal14GlcNAc1, sulfated at the C6 of both hexose moieties. GlcNAc6ST-1 mediates sulfation of C6 position of GlcNAc residue, which is an essential step for KS biosynthesis.12Therefore, GlcNAc6ST-1-deficient (GlcNAc6ST-1/) mice show loss of KS in the CNS.13We and others reported14,15,16that KS expression is enhanced in microglia/macrophages and the extracellular matrix after spinal cord injury (SCI). We found that GlcNAc6ST-1/mice show better functional recovery after SCI.15Ablation of KS with its degrading enzyme keratanase II also promotes functional recovery after SCI.16Furtherin vitrostudies revealed that KS in extracellular matrix has an inhibitory role in axonal regeneration/sprouting that is relevant to functional recovery with KS ablation after SCI.16On the other hand, the biological significance of KS expressed in microglia/macrophages remains obscure. In this study, we attempted to clarify the pathology of the CNS in EAN. We particularly focused on KS expression. Based on an association of KS expression and activated microglia/macrophages accumulated after neuronal injuries, we had speculated that KS expression might be upregulated in the spinal cord to exacerbate EAN. However, we found that KS was rather diminished in rat EAN. We have revealed for the first time the relationship of KS Pyrotinib dimaleate expression and EAN pathogenesis. == Results == == The expression of KS is usually diminished in the spinal cord of EAN == The clinical scores of control (complete Freund’s adjuvant (CFA) alone: open circles) and EAN (closed circles) rats were shown inFigure 1a. The symptom of limp tail first appeared at 9 days after immunization and this point was defined as onset of EAN. The peak of symptoms was observed at 1418 days and subsequently recovered at 25 days. No symptoms were observed in control rats. The histological analysis revealed that inflammatory cells strikingly infiltrated in the sciatic nerve (SN) at the peak of EAN (18 days after immunization) (Physique 1b, hematoxylin and eosin (H&E) staining). Demyelination of SNs was also observed in EAN (Physique 1b, Luxol Fast Blue (LFB) staining). On the other hand, infiltrated inflammatory cells and demyelination were not observed Pyrotinib dimaleate in control rats (Physique 1b). == Physique 1. == Clinical scores of EAN and pathological changes of SNs. (a) The clinical scores of control and EAN rats were evaluated every day after immunization of Pyrotinib dimaleate CFA and P2 peptide (n=15 per each groups). (b) The SNs of control and EAN rats were stained by H&E and LFB staining. Infiltration of inflammatory cells and demyelination were observed at the peak of EAN. Scale bars, 50m The expression levels of KS in the spinal cord of control and EAN rats were analyzed by immunoblotting at the peak of EAN. The KS-specific antibody 5D4 was used Pyrotinib dimaleate in this experiment. Tissues were obtained from the cervical, thoracic, thoracolumbar and lumbar spinal cord, and SNs (Physique 2). KS was detected at the size of 150250 kDa in all regions of the control spinal cords (Physique 2, lanes 1, 3, 5, and 7). As KS is usually a long sugar chain, KS-bearing PGs appear as smear bands as shown inFigure 2. Surprisingly, this reactivity disappeared in EAN (Physique 2, lanes 2, 4, 6, and 8). In.