Following dehydration, samples were incubated in propylene oxide in tightly closed containers for 1?h at room temperature, then 1?h in a 1:1 mixture of propylene oxide/epon (epoxy embedding medium kit; Sigma-Aldrich), and finally kept at 4?C in epon only overnight. LPA signaling may ameliorate the course of disease in experimental autoimmune neuritis (EAN). Methods We induced active EAN by inoculation of myelin protein 2 peptide (P255C78) in female Lewis rats. Animals received the orally available LPA receptor antagonist Rabbit polyclonal to KLF4 AM095, specifically targeting the LPA1 receptor subtype. AM095 was administered daily via oral gavage in a therapeutic regimen from 10 until 28?days post-immunization (dpi). Analyses were based on clinical testing, hemogram profiles, immunohistochemistry and morphometric assessment of myelination. Results Lewis rats treated with AM095 displayed a significant improvement in clinical scores, most notably during the remission phase. Cellular infiltration of sciatic nerve was only discretely affected by AM095. Hemogram profiles indicated no impact on circulating leukocytes. However, sciatic nerve immunohistochemistry revealed a reduction in the number of Schwann cells expressing the dedifferentiation marker Sox2 paralleled by a corresponding increase in differentiating Sox10-positive Schwann cells. In line with this, morphometric analysis of sciatic nerve semi-thin sections identified a significant increase in large-caliber myelinated axons at 28 dpi. Myelin thickness was unaffected by AM095. Conclusion EPZ020411 Thus, LPA1 signaling may present a novel therapeutic target for the treatment of inflammatory neuropathies, potentially affecting regenerative responses in the peripheral nerve by modulating Schwann cell differentiation. strong class=”kwd-title” Keywords: Lysophosphatidic acid (LPA), Experimental autoimmune neuritis (EAN), Inflammatory neuropathy, GuillainCBarr-syndrome, Schwann cell, Differentiation, Demyelination, Remyelination, Sox2, Sox10 Introduction Immune-mediated neuropathies represent a heterogeneous group of rare peripheral nerve disorders comprising both acute and chronic forms. The prototype of an acute monophasic inflammatory polyneuropathy is the GuillainCBarr syndrome (GBS), with a reported incidence rate of 1C4 cases per 100,000 worldwide [1]. The prevalence of chronic inflammatory demyelinating polyneuropathy (CIDP) is estimated to be 1C2 of 100,000 individuals [2]. While GBS and CIDP are distinct disorders, they share clinical and pathogenetic aspects: immunomodulatory therapies such as plasma exchange or intravenous immunoglobulins (IVIg) represent effective treatment options in both conditions. Moreover, the presence of cellular infiltrates consisting mainly of T-lymphocytes and macrophages in nerve biopsies of GBS and CIDP patients as well as in the respective animal models, further supports the idea of an immune-mediated pathogenesis for either condition [3, 4]. Given the substantial body of evidence indicating autoimmune-driven damage to neurons and glial cells as major pathological hallmark of inflammatory neuropathies, cellular and humoral immune responses against the peripheral nervous system (PNS) have mostly been considered in isolation, largely ignoring the acute and potentially long-lasting impact on physiological homeostasis in the peripheral nerve. While the detrimental effects of innate EPZ020411 and adaptive immune responses have been well-defined in autoimmune neuropathies [5], demyelination does not appear to be an exclusive result of self-directed immunity, but rather a result of Schwann cell dedifferentiation and thus the adoption of a non-myelinating phenotype in the inflammatory milieu via the secretion of cytokines and various other cues from T-lymphocytes and their effector cells [6]. Schwann cells, as the myelin-forming glial cell population of the PNS, have long been considered as passive bystanders in peripheral neuroinflammation. While Schwann cells have clearly been shown to fulfill important functions beyond EPZ020411 building myelin sheaths [7], such as providing trophic and structural support to axons, several lines of evidence further support a view that strongly indicates an enormous phenotypic plasticity of Schwann cells. Indeed, Schwann cells are increasingly accepted to be capable of responding to a wide range of stimuli and appear as facultative immunocompetent cells that may even actively orchestrate inflammatory processes in the PNS, functionally resembling innate immune cells such as macrophages [8C10]. A recent study took the effort to analyze Schwann cell differentiation in NOD/B7-2-knockout mice, a spontaneous inflammatory demyelinating neuropathy model that shares several pathological features with CIDP. It was demonstrated that the onset of neuroinflammation resulted in an upregulation of dedifferentiation-associated genes. Most notably, the downregulation of Krox20, the master regulator of peripheral myelination, was paralleled by the induction of c-Jun expression, a dedifferentiation marker [11]. These findings appear particularly revealing in light of a pilot immunohistochemical study that investigated the expression of c-Jun in nerve and skin biopsies from neuropathy patients. Whereas c-Jun expression was barely detectable in nerves of healthy controls, nerves from patients with different neuropathies,.