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The interplay between immune cells and tumor cells determines the fate of tumorigenesis. Targeting the abnormal immune response of tumors has been recently achieved great success in some patients. Emerging evidence demonstrated the nervous system plays vital roles in immune regulation, but if the nervous system affects the immune-tumor response and the possible mechanism involved remain largely unexplored. Here, we report that Schwann cells, the major component of the peripheral nervous system (PNS), induce M2 polarization of macrophages by secreting cytokines and chemokines, and these polarized macrophages promote the proliferation of lung cancer cells. We cocultured peripheral blood mononuclear cells (PBMCs) with Schwann cells or treated PBMCs with the culture supernatant of Schwann cells. We found that both treatments induced M2 polarization of the macrophages in peripheral blood mononuclear cell cultures. We performed a bioinformatic analysis of the transcriptome of Schwann cells and analyzed cytokines and chemokines by ELISAs. We found that Schwann cells secreted high levels of CCL2, CXCL5, CXCL12, and CXCL8. CCL2 promotes the M2 polarization of macrophages. Furthermore, we isolated CD14-positive macrophages that were cocultured with the Schwann cells and treated A549 and H1299 lung cancer cells with these macrophages. We found that the Schwann cell-polarized macrophages increased the proliferation of the lung cancer cells. Our study sheds new light on the involvement of the PNS in the regulation of tumor progression via a "Schwann cell"-"immune cell"-"tumor cell" axis., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Although peripheral nerves are capable of regeneration, advanced age decreases the potential for functional recovery after injury. The cellular mechanisms for this are not currently understood. Here, we performed sciatic nerve grafting with young (2 months old) and aged (18 months old) Brown-Norway male rats, in which 1 cm nerve grafts from young or aged rats were sutured into nerves of young or aged rats. Axons were allowed to regenerate until the nerve grafts and distal nerves were harvested at 1, 3, and 7 days and 2 and 6 weeks. At 6 weeks, our data suggested that young nerve grafts supported regeneration better than aged nerve grafts. In addition, myelin debris clearance was inhibited in young nerves when grafted into aged rats, but clearance was faster when aged nerves were grafted into young rats. Further analysis revealed that aged macrophages have delayed migration into injured nerve, and macrophages and Schwann cells from aged rats were less phagocytic for myelin debris in vitro. To understand these impairments, expression levels of pro- and anti-inflammatory cytokines were analyzed at 1 day after injury. Based on these levels, there was not a clear polarization to either an M1 or M2 phenotype; however, expression levels of IL-6, IL-10, CCL2 (MCP1), and Arg-1 were decreased in aged nerves. Taken together, both macrophages and Schwann cells had attenuated responses to nerve injury in aged rats, leading to inefficient clearance of debris and impaired axonal regeneration., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Schwann cells are primarily discussed in the context of their ability to form myelin. However there are many subtypes of these neural crest derived cells including satellite cells of the dorsal root ganglia and autonomic ganglia, the perisynaptic Schwann cells of the neuromuscular junction and the non-myelin forming Schwann cells which ensheathe the unmyelinated fibres of the peripheral nervous system which are about 80% of peripheral nerves. This review discusses the many functions of these Schwann cell subsets including their seminal role in axonal ensheathment, perineuronal organisation, maintenance of normal neural function, synapse formation, response to damage and repair and an increasingly recognised active role in pain syndromes., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Interleukin-6 plays an important role in peripheral nerve regeneration. We recently reported that IL-6 targets Schwann cells in the peripheral nerve for its function. In this study, we analyzed genes whose expression is regulated by IL-6 in a cell line derived from Schwann cells, the peripheral glia, using the Illumina gene microarray. At measurements 3 and 12h after IL-6 treatment, 35 genes were found to be upregulated by IL-6. Most upregulated genes were proinflammatory genes that are known to be induced in inflammatory conditions. Interestingly, the expression of immunoproteasome subunits was upregulated by IL-6 in Schwann cells. Treatment with forskolin, an agent that mimics axonal signaling, suppressed the expression of IL-6-inducible genes. Finally, we found for the first time that sciatic nerve injury induced immunoproteasome expression in vivo. These findings indicate that IL-6 is involved in peripheral nerve regeneration by regulating proinflammatory signaling in Schwann cells.

Thirty schwannomas from 22 cows were examined immunohistochemically. All were positive for vimentin and Ki-67 but negative for pancytokeratin, neurofilament, and desmin. S-100 immunolabelling varied between and within lesions. The numbers of tumours giving positive results for S-100, neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) were 16, 30 and 25, respectively. It was concluded that vimentin-positive tumours suspected to be schwannomas should also be immunolabelled for NSE and GFAP to confirm the diagnosis.

Schwann cells play an important role in peripheral nerve regeneration. Upon nerve injury, Schwann cells are activated and produce various proinflammatory cytokines and chemokines, resulting in the recruitment of macrophages and the phagocytosis of myelin debris. However, it is unclear how nerve injury induces Schwann cell activation. Recently, it was reported that necrotic cells induce immune cell activation via toll-like receptors (TLRs). This suggests that the TLRs expressed on Schwann cells may recognize nerve injury by binding to the endogenous ligands secreted by the damaged nerve, thereby inducing Schwann cell activation. To explore such a possibility, we stimulated rat Schwann cells with necrotic neuronal cells (NNC). The stimulation of Schwann cells with NNC induced the expression of various inflammatory mediators, including TNF-alpha and iNOS. Studies on the NNC-mediated intracellular signaling pathways revealed that p38 and JNK are involved in the NNC-mediated Schwann cell activation. In addition, NNC-induced proinflammatory gene expression was reduced in mouse Schwann cells derived from TLR2 or TLR3 knockout mice. In summary, these results suggest that necrotic neuronal cells induce inflammatory Schwann cell activation via TLR2 and TLR3, which might be involved in Wallerian degeneration upon peripheral nerve injury.

The molecular events that occur at the early phase of many demyelinating neurodegenerative diseases are unknown. A recent demonstration of rapid demyelination and axonal injury induced by Mycobacterium leprae provides a model for elucidating the molecular events of early nerve degeneration which might be common to neurodegenerative diseases of both infectious origin and unknown etiology. The identification of the M. leprae-targeted Schwann cell receptor, dystroglycan, and its associated molecules in myelination, demyelination and axonal functions suggests a role for these molecules in early nerve degeneration.

This study demonstrates that rat Schwann cells can reactivate resting experimental allergic neuritis generating P(2) and P(2) peptide specific CD4(+) T cell lines. T cell proliferation was significantly greater to P(2) than to P(2) peptide (SP-26) or ovalbumin (OA). Four-level analysis of variance showed that T cell proliferation with endogenous or exogenous P(2) was not significantly different for Schwann cells plus cytokine IFN-gamma (P = 0.5071) unlike P(2) peptide or OA specific T cells (P = 0.0056 and 0.0003, respectively). Untreated Schwann cells were more effective inducers than irradiated or fixed Schwann cells. As stimulated CD4(+) P(2) T cells produce IFN-gamma and TNF-alpha, this could exacerbate blood nerve barrier breakdown that has been increasingly implicated in inflammatory demyelinating neuropathies (IDNs). This would permit entry of antibodies and complement, thereby contributing to the demyelination process. Schwann cell induced reactivation of CD4(+) T cells may therefore play a role in IDNs., (Copyright 1999 Academic Press.)

In this report we describe a highly sensitive large-scale screening assay that uses viable adherent cells. The newly developed test design combines the advantages of live cell immunocytochemistry with the versatility of a conventional ELISA technique. Culturing of target cells as well as incubation with antibodies is done in the same microtiter plate. No processing of cells prior to incubation with the antibodies, such as fixation or enzymatic detachment of the cells, is performed. This eliminates possible factors that might interfere with antibody-antigen recognition and results in a dramatically increased sensitivity that is comparable to cell-free ELISA procedures with an assay detection limit reproducibly between 0.004 and 0.002 micrograms/ml. Furthermore, this test design is convenient for the rapid identification of antibodies against differentiation-dependent antigens. Incubation in parallel with the same antibody of different cell types (forskolin-stimulated Schwann cells or fibroblasts) or cells grown under different conditions (forskolin-stimulated and non-stimulated Schwann cells) facilitates the selection of antibodies displaying genotypic or phenotypic specificity. Since culture of target cells and the detection of antibodies is done on one microtiter plate, it is not only possible to detect cell surface molecules but also secreted molecules that remain bound to the cell surface or the culture substrate. Compared to other previously introduced cell-ELISAs, our protocol offers the following advantages: (i) increased sensitivity, (ii) convenience for large-scale screening, (iii) optimal identification of antibodies reacting with native molecules, and (iv) identification of differentiation-dependent antigens. Since this assay could also be used in studies examining the regulation of cell surface molecules at a semiquantitative level it may be of general relevance.

Objectives: Although it is now reasonably certain that granular cell tumors derive from Schwann cells, the histogenesis of congenital epulis, which is largely isomorphic with granular cell tumor, remains unclear. A study was undertaken to compare the immunophenotype of these tumors with particular emphasis on the expression of matrix proteins and macrophage markers because such information is not available in the literature., Study Design: Four granular cell tumors and two congenital epulis were immunostained with a panel of 29 antibodies. Two congenital epulis and one granular cell tumor were investigated by electron microscopy, the latter also by immunoelectron microscopy., Results: Many similarities in immunostaining were found, for example, both tumor types were CD68+, Ki-M1P+, lysozyme-, vimentin+, fibronectin+, laminin+, lectin PHAE+, and lectin WGA+. However, differences were also noted, for example, granular cell tumor was always S100 protein+, but only one congenital epulis case was reactive (weak reactivity after microwave treatment), and staining with the proliferation markers anti-proliferating cell nuclear antigen and MIB 1 was found only in congenital epulis. Both tumor types exhibited pericellular and diffuse cytoplasmic staining for fibronectin and laminin., Conclusions: The hypothesis that congenital epulis and granular cell tumor would exhibit similar reactivity for macrophage markers was confirmed: both were reactive with anti-CD68 and Ki-M1P and nonreactive with MAC387, anti-lysozyme, and 3A5. Intracytoplasmic staining for fibronectin and laminin, which has not been described previously in these tumors, appears to be a characteristic feature common to both tumors. This finding suggests that there could be a disturbance of synthesis and secretion of extracellular matrix proteins or a derangement of their receptor systems. This theory could be supported by the finding of intracytoplasmic CD49e-positive material in two cases.

Neonatal rat Schwann cells were characterized with regard to their immune functions in vitro. Without stimulation they displayed low levels of ICAM-1, but not of MHC class II gene products on their surface. Expression of both immune molecules was upregulated by IFN-gamma. TNF-alpha acted synergistically, but had no effect when given alone. ICAM-1 expression reached its maximum within 24 hr, whereas I-A plateaued only after 3 days of cytokine treatment. Increased expression of recognition molecules on Schwann cells correlated well with enhanced activation of CD4+ autoimmune T cell lines between Day 1 and 2. T cell activation was blocked by adding monoclonal antibodies directed against I-A molecules, whereas ICAM-1-specific antibodies exerted a mild costimulatory effect. We conclude that Schwann cells may exert potent immunoregulatory functions by expressing MHC and adhesion molecules, which may be further upregulated by Th1-type cytokines released by immunoinflammatory T cells in the lesion.

Serum samples from 52 patients with the acute Guillain-Barré syndrome (GBS), 19 patients with other neurological disorders, and 18 healthy volunteers were tested for cytotoxicity in cultures of rat Schwann cells and dorsal root ganglion neurons. The samples were also examined by enzyme-linked immunosorbent assay for IgG and IgM antibodies against various acidic and neutral glycolipids. Samples from 16 of the 52 (31%) acute GBS patients and from 1 of the 6 patients with chronic inflammatory demyelinating polyneuropathy produced myelin breakdown in culture. Although 10 of the 16 cytotoxic acute GBS serum samples contained anti-glycolipid immunoglobulins, there was no correlation in individual samples between cytotoxic activity and the presence of antibodies against specific glycolipids. While our results do not exclude a role for anti-glycolipid antibodies in the pathogenesis of the acute GBS, the cytotoxic effects of acute GBS serum in cultures of Schwann cells and sensory neurons are probably not due to these antibodies alone.

The expression of class II antigen was studied in sural nerve biopsies from patients with peripheral neuropathies. These included patients with chronic demyelinating polyradiculoneuropathy (CIDP), non-immune mediated neuropathies of diverse etiologies and controls without evidence of neuropathy. The major finding in CIDP was a marked increase in class II expression on Schwann cells. Endoneurial Schwann cell staining to the same degree as in CIDP was seen in diabetic symmetric proximal motor neuropathy, neuropathies associated with monoclonal gammopathies and hereditary sensory and autonomic neuropathy type 1. In the control nerves and the other non-immune mediated neuropathies class II expression was mainly restricted to endothelial and perineurial cells. Increased endoneurial expression of class II antigen was found to correlate with elevated cerebrospinal fluid (CSF) protein levels but not with other clinical variables or demyelination as defined by electrophysiologic criteria or teased fiber analysis. The increased expression of class II antigen on Schwann cells may be indicative of a breakdown in immunological tolerance but should not be used as a diagnostic marker for dysimmune neuropathies due to overlap with non-immune mediated neuropathies.

The normal neuromuscular synapse is formed by the intimate association of nerve endings, postsynaptic end-plate foldings in the muscle fiber, and nonmyelinating Schwann cells (SC) sealing the synaptic ramifications. Because SC have been recognized recently to have an immunogenic potential inducible to present protein autoantigens to autoimmune T lymphocytes, and considering their close proximity to the acetylcholine receptor (AChR)-bearing postsynaptic membranes, presentation of soluble and membrane vesicle-bound AChR to appropriate T cells was investigated. Short-term monolayer cultures of SC isolated from neonatal rat sciatic nerves, as well as cells of an immortalized SC line of similar origin, were fully able to present the relevant molecular epitopes to major histocompatibility complex (MHC) compatible AChR-specific T line lymphocytes immunogenically. Presentation of AChR was restricted by RT1.B (I-A) MHC class II products. Both types of cultured rat SC were inducible to expression of MHC class I and II products, and they were able to phagocytose AChR-enriched membrane vesicles preferentially. In contrast, phagocytosis of latex particles by SC was negligible. These data qualify perisynaptic SC as potential presenter cells of autoimmunogenic AChR in myasthenia gravis. Thus, SC may play a critical and as-yet unpredicted regulatory role in the cellular pathogenesis of myasthenia gravis.

Sera from rabbits with EAN induced by sensitization with galactocerebroside (GalC-EAN) bound to the surface of Schwann cells and oligodendrocytes in rat nervous system dispersion cultures. Sera from rabbits with bovine femoral nerve-induced EAN (FN-EAN) bound to Schwann cells, oligodendroglia and occasional fibroblasts. Sera from animals with bovine spinal cord-induced EAE (SC-EAE) bound to these cells and to some astrocytes as well. Absorption of the capacity to bind to oligodendroglia and Schwann cells suggests that GalC is the major, if not the only surface antigen on these two cell types to which these sera bind. The capacity of GalC-EAN, SC-EAE, and FN-EAN sera to bind to the surface of the cells responsible for myelin synthesis in both PNS and CNS correlates with the ability of these sera to cause both PNS and CNS demyelination in vitro and PNS demyelination in vivo.

The sera of 9 patients with benign IgM paraproteinaemia and chronic sensorimotor neuropathy were tested for reactivity to human peripheral nerves by the indirect immunoperoxidase method. They reacted in very high titre (10(-3)-10(-6) with a cytoplasmic Schwann cell component, and to lesser degree, with peripheral nerve myelin (10(0)-10(-3). The Schwann cell staining was in the form of perinuclear cytoplasmic granules and was only seen with adult nerve. The distribution of the antigen was similar to that of the metachromatically staining Pi-granules of Reich, which accumulate in the peripheral nerves with age. Specific activity was present in the IgM and F(ab)2 fractions and could be absorbed out with peripheral nerve tissue, but not with liver. Reactivity is not a simple function of the IgM level, since many IgM paraproteins do not react. The antibody is species specific and binds to human, but not to any component of rabbit, rat or guinea pig sciatic nerves. Antigenicity is removed by pretreatment of the nerve with chloroform-methanol or periodate, but not protease or trypsin. Reactivity is restored, after periodate treatment, by exposure to sodium borohydride. It is suggested that some IgM paraproteins have a specificity for a myelin glycolipid or glycoprotein, which normally accumulates in the Pi-granules of the Schwann cell cytoplasm as a function of age.

Allogenic graft rejection leads to rapid tissue destruction of nerves transplanted directly into a muscle lodge. If the nerves are enclosed in 5.0 micron pore chambers and transplanted into the peritoneal cavity, there is no allogenic graft rejection. The phagocytosis of myelin by invading cells is, however, not disturbed, showing that these cells can distinguish the degenerating myelin from the Schwann cell without being responsive to the Schwann cell's allotype. If the allografts are allowed to predegenerate for 4 wk in 0.22 micron pore chambers which do not admit any cells, there is a striking mitigation of the allogenic graft rejection if the nerves are subsequently released from the chamber. Myelin phagocytosis in such nerves is also reduced. These observations indicate the existence of a hierarchy of cellular recognition mechanisms involved in nerve tissue degradation. Phagocytosis of the myelin sheath by macrophages involves recognition mechanisms which differ from those of the allogenic rejection of the Schwann cell, presumably mediated by T lymphocytes.

Immunoelectron microscopy is an important tool used to determine the precise location of immune complexes. Standard concentrations of glutaraldehyde destroy these complexes. This paper describes a method in which the period of glutaraldehyde fixation is shortened by concomitant microwave treatment. Using 1.25% glutaraldehyde and microwave fixation ideal preservation and demonstration of MHC class I antigen on Schwann cells was obtained by the peroxidase method.