Onion bulb cells in mice deficient for myelin genes share molecular properties with immature, differentiated non-myelinating, and denervated Schwann cells

Onion bulb formation is a pathological feature observed in peripheral nerves of patients suffering from inherited peripheral neuropathies such as Charcot-Marie-Tooth and Déjérine-Sottas diseases. An onion bulb consists of small circumferentially oriented (supernumerary) cells and their processes surrounding a large caliber axon. In the present study, we investigated the molecular phenotype of supernumerary cells at the light and electron microscopic levels. The major motor (quadriceps muscle) branch of the femoral nerve from 16- to 24-month-old mice with an inactivated allele of the myelin protein zero gene or deficient for myelin-associated glycoprotein (MAG; P0(+)- and MAG--mice, respectively), which have numerous onion bulbs, was teased to obtain single nerve fibers, which were then processed for immunocytochemistry. Corresponding nerves from wild-type mice served as controls. In both P0(+)- and MAG--mice, supernumerary cells expressed S-100, the low-affinity nerve growth factor receptor (p75, NGFr), the cell adhesion molecule L1, the neural cell adhesion molecule (N-CAM), and glial fibrillary acidic protein (GFAP). At the electron microscopic level, the cell surface of supernumerary cells was NGFr immunoreactive and L1 and N-CAM were expressed at points of contact between supernumerary cells. NGFr, L1, and N-CAM were also present in the basal lamina surrounding myelinated axons associated with onion bulbs. Both S-100 and GFAP immunoreactivities were seen in the cytoplasm of supernumerary cells. In contrast, in wild-type mice myelinating Schwann cells only expressed S-100 intracellularly and L1 and N-CAM in their basal lamina, whereas non-myelinating Schwann cells expressed all five molecules investigated. The present study indicates that supernumerary cells in onion bulbs have a molecular phenotype characteristic of immature, differentiated non-myelinating, and denervated Schwann cells, thus excluding the possibility that supernumerary cells are perineurial cells.

Expression of the rat S100A1 gene in neurons, glia, and skeletal muscle

Using a rat S100A1 cDNA probe, S100A1 expression has been documented in rat C6 glioma cells, a cell line previously thought to express only the S100B protein. To identify the molecular mechanisms which target S100A1 gene expression to specific cell types, the rat S100A1 gene was cloned, and functional analysis of the 5' flanking region of the gene was performed. The rat S100A1 gene was located in an 8.5 kb BamHI genomic fragment which contained 3 exons plus 1.6 kb of 5'-upstream and 0.37 kb of 3'-downstream flanking sequence. A single transcription initiation start site and a single polyadenylation signal were identified in this gene. A number of potential regulatory consensus sequences were identified in the rat S100A1 gene including general transcription factor binding sequences (TATA box, GC box and CCAAT box), cAMP regulated sequences (CRE), skeletal muscle specific sequences (E-box and M-CAT), an S100 protein element, and a (GCT) trinucleotide repeat. Analysis of an S100A1 promoter-CAT construct by ribonuclease protection assay demonstrated that this gene is functional in three S100A1 expressing cell lines, C6 cells, PC12 cells and L6 cells. CAT constructs containing progressive deletions of the S100A1 promoter region revealed a positive regulatory element in skeletal muscle (L6) cells between -1600/-1081. The fact that these same sequences were negative in glial (C6) cells and neutral in neuronal (PC12) cells suggests that this region plays a major role in targeting S100A1 expression to specific cell types. The -1081/+10 region contained both positive and negative elements, some of which were cell-type specific. Thus, S100A1 expression is under complex transcriptional control which involves positive and negative elements as well as cell type specific elements.

[Observations of cellular differentiation behaviour in adenoid cystic carcinoma of human salivary gland in vitro]

The celluar differentiation behaviour of adenoid cystic carcinoma (ACC) of salivary gland was investigated in vitro with immunohistochemistry. The results showed that the cells of ACC-2 and ACC-3 cell lines can express some marker proteins in vitro including S-100 protein, actin, myosin which is characterized as a feature of myoepithelial cells. When differentiation inducer, dB-cAMP, was added to the monolayer cells cultured in dishes, the marker protein expression increased and the CEA changed to positive. The cellular differetiation behaviour of ACC cells is related to the proliferate speed of cells. Some cells manifested finger ring-like when the culture condition was changed, it means that these cells have the secretory function. If the ACC cells were suspended singly in collagen gels which performed as an extracellular matrix they grew and formed the tubule-like structure. The results will help us to understand the histogenesis of ACC, the source of myoepithelial cells in ACC and the variety of histological structures of ACC.

Expression of S-100 protein and glial fibrillary acidic protein in cultured submandibular gland epithelial cells and salivary gland tissues. Histogenetic implication for salivary gland tumors

S-100 protein and glial fibrillary acidic protein (GFAP) were studied in human salivary gland tissues and human cultured submandibular gland epithelial cells. Immunohistochemically, ductal cells in normal salivary gland tissues were positive for S-100 protein and GFAP, but myoepithelial cells were uniformly negative. Immunocytochemically, cultured submandibular gland ductal cells were positive for S-100 protein and GFAP. By immunoblotting analysis of the cultured cell lysates, a 6.5-kd S-100 protein was detected. This band corresponded to S-100 protein purified from bovine brain. The cultured submandibular gland cells expressed 49- and 54-kd GFAP polypeptides. These results have important implications for the histogenesis of salivary gland tumors.

A decreased incidence of neuroblastomas in Down's syndrome and overproduction of S-100 b protein

Neuroblastoma, one of the most frequent solid tumors found in childhood, is very rare in Down's syndrome subjects. This lack could possibly be due to overproduction of S-100 b protein for the following reasons: 1) the gene coding for S-100 b protein is situated on chromosome 21, and the protein is overproduced via a gene dosage effect; 2) S-100 b protein is found in glial cells and Schwann cells of the central and peripheral nervous system and has been shown to have a differentiating effect on normal neural cells; 3) neuroblastomas with a stroma rich in S-100 protein have a good prognosis. Preliminary studies demonstrated an inhibition of growth of two human neuroblastoma cell lines in the presence of S-100 b protein compared to controls. It is postulated that S-100 b protein may inhibit the development of neuroblastomas in Down's syndrome either antenatally, or after birth and may be a therapeutic agent against neuroblastoma.

Granular cell tumor expressing myogenic markers in the prostate

A granular cell tumor in the prostate of a 72 year old male is reported. The tumor nest was composed of large polygonal tumor cells, possessing cytoplasmic eosinophilic granules which were positive with PAS stain and resistant to diastase digestion. Immunohistochemically, most tumor cells were strongly positive with anti-alpha-smooth muscle actin and -neuron specific enolase antibodies. Only a few scattered tumor cells were reacted with anti-S-100 protein antibody. These findings might suggest smooth muscle differentiation of this case, and provide an additional insight into the histogenesis of granular cell tumors, especially in their heterogeneity.

Appearance of neuronal S-100 beta during development of the rat brain

In addition to being an astroglial protein, S-100 beta is localised in distinct populations of neurons in the adult rat hindbrain. We report, here, the expression of S-100 beta in both neurons and glia of the rat brain during development. Prenatally, S-100 beta immunoreactivity was confined to glial cells close to the germinal zone. After birth, S-100 beta positive glial cells were seen mainly in the brainstem and cerebellum, while only a few were detected in cerebral cortex and hippocampus. The number of S-100 beta containing glial cells increased steadily during the first 2 postnatal weeks after which the adult pattern was attained. No S-100 beta containing neurons were present prenatally. The first S-100 beta containing neurons were seen in the mesencephalic trigeminal nucleus at postnatal day 1 (P1), and in the motor trigeminal nucleus at P3. Neuronal S-100 beta immunoreactivity in other nuclei was mostly attained from the 10th to the 21st postnatal day. The neuronal S-100 beta immunoreactivity was first detected in the cell nuclei during development, then increased in the cytoplasm with ages. A nuclear staining in many immunoreactive neurons persisted until the adult. It usually took 1 to 2 weeks for neuronal S-100 beta to attain the adult staining pattern, i.e., heavy staining of the cytoplasm and processes, after its appearance. The forebrain never contained S-100 beta positive neurons. The S-100 beta is first expressed in glial cells, suggesting it is primarily of the glial origin. Coupled with neurotrophic effects of the protein, the time course of neuronal S-100 beta expression during the critical period of neuronal development implies that it may be involved in neuronal differentiation and maturation.

In vivo and in vitro evidence supporting a role for the inflammatory cytokine interleukin-1 as a driving force in Alzheimer pathogenesis

Interleukin-1 (IL-1), an inflammatory cytokine overexpressed in the neuritic plaques of Alzheimer's disease, activates astrocytes and enhances production and processing of beta-amyloid precursor protein (beta-APP). Activated astrocytes, overexpressing S100 beta, are a prominent feature of these neuritic plaques, and the neurite growth-promoting properties of S100 beta have been implicated in the formation of dystrophic neurites overexpressing beta-APP in neuritic plaques. These facts collectively suggest that elevated levels of the inflammatory cytokine IL-1 drive S100 beta and beta-APP overexpression and dystrophic neurite formation in Alzheimer's disease. To more directly assess this driver potential for IL-1, we analyzed IL-1 induction of S100 beta expression in vivo and in vitro, and of beta-APP expression in vivo. Synthetic IL-1 beta was injected into the right cerebral hemispheres of 13 rats. Nine additional rats were injected with phosphate-buffered saline, and seven rats served as uninjected controls. The number of astrocytes expressing detectable levels of S100 beta in tissue sections from IL-1-injected brains was 1.5 fold that of either control group (p < 0.01), while tissue S100 beta levels were approximately threefold that of controls (p < 0.05). The tissue levels of two beta-APP isoforms (approximately 130 and 135 kDa) were also significantly elevated in IL-1-injected brains (p < 0.05). C6 glioma cells, treated in vitro for 24 h with either IL-1 beta or IL-1 alpha, showed significant increases in both S100 beta and S100 beta mRNA levels. These results provide evidence that IL-1 upregulates both S100 beta and beta-APP expression, in vivo and vitro, and support the idea that overexpression of IL-1 in Alzheimer's disease drives astrocytic overexpression of S100 beta, favoring the growth of dystrophic neurites necessary for evolution of diffuse amyloid deposits into neuritic beta-amyloid plaques.

Rhinophyma--unusual expression of simple-type keratins and S100A in sebocytes and abundance of VIP receptor-positive dermal cells

Rhinophyma represents a severe variant of rosacea, a common mid-facial erythematous dermatosis. Increased blood flow and pooling in skin are thought to be involved in its pathogenesis. Since neuropeptides and their receptors are responsible for local blood flow regulation, immunolocalization for the vasoactive intestinal peptide (VIP)-receptor(R) was performed in slice biopsies taken from five patients with glandular rhinophyma. Additional immunostainings included intermediate filaments (keratin, vimentin) and neuroglandular antigen (NGA). In contrast to controls, rhinophyma disclosed not only a more dense distribution of VIP-R positive cells within the endothelium but immunoreactive perivascular large cells. The immature sebocytes stained positive with monoclonal antibody Cam5.2 against glandular antigens and polyclonal anti-S100A. Elastotic connective tissue in the dermis showed a strong immunoreactivity for vimentin and NGA. From these results we suggest that, (a) ligands of the VIP-R may contribute to vascular and dermal alterations in rosacea and (b) immature sebocytes show an unusual antigen expression of S100A and glandular keratin.

Regulation of the rat S100 beta gene expression: the role of the 2 kb 5'-upstream sequence in glial specific expression

We have studied the role of the 2047 bp 5'-upstream region and 232 bp first exon sequence of the rat S100 beta gene in glial specific expression. S100 beta luciferase expression vectors carrying serial deletions of the S100 beta 5' upstream sequence were constructed and transiently transfected into the peripheral nervous system (PNS) glial-type cell line RT4-D6, the PNS neuronal-type cell line RT4-E5, and the central nervous system (CNS) glial-type cell line C6. The hepatoma cell line HTC was also transfected as a nonneural control. From this functional analysis, we found a glial-specific positive regulatory sequence(s) mapped between -583 and -106 relative to the transcriptional start site. This region confers a significantly higher level of luciferase expression in the glial-type cell lines RT4-D6 and C6 than in the neuronal cell line RT4-E5 and the hepatoma cell line HTC. Also, a non-cell type specific positive regulatory element was identified in the first exon sequence between +78 and +232. Though non-cell type-specific, it was found to have a predominant effect in glial cells. From these observations, we have concluded that the 2047 bp 5'-upstream region and 232 bp of the first exon sequence confers the high levels of S100 beta expression in glial cells through these two positive elements.

Transient expression of S-100 by melanotropes of the rat pituitary intermediate lobe during development

S-100, an acidic calcium-binding protein, is co-localized with vimentin in glial-like cells in the adult rat pituitary intermediate lobe. S-100 and melanotrope markers were not co-localized in the adult. During development, S-100 and vimentin were not co-localized but appeared in cells with different morphological characteristics. S-100 was co-localized with POMC mRNA and beta-endorphin during prenatal time and the first three postnatal weeks. This was demonstrated by double-label immunohistochemistry, using combinations of antisera against S-100, vimentin and beta-endorphin, and in situ hybridization histochemistry for POMC mRNA combined with immunohistochemistry for S-100. In the second and third weeks of postnatal development, S-100 was observed in fewer melanotropes and more frequently in stellate cells, which also expressed vimentin. Thus, S-100 appeared to be transiently expressed in melanotropes during prenatal and early postnatal development. S-100 serves as a neurotrophic and glial maturation factor in the CNS. Since S-100 expression in melanotropes coincides with the onset of dopaminergic innervation and morphological changes in glial-like cells of the lobe, it could have similar functions in the rat pituitary intermediate lobe.

Expression of ret proto-oncogene products in the hypoganglionic segment of the small intestine of congenital aganglionosis rats

The ret proto-oncogene (proto-ret) encodes a receptor tyrosine kinase that contains a cadherin-related sequence in the extracellular domain, which plays an important role in control of normal cell growth and differentiation. Recent studies have shown that familial Hirschsprung's disease is closely linked to the proto-ret locus. Immunohistologically studies on congenital aganglionosis rats were made using polyclonal antibody generated for the carboxy-terminal sequence of the proto-ret products. Immunoreactivity was investigated in the small and large intestines of mutant and control rats. It was increased in the ganglia of the hypoganglionic segment of the small intestine and was minimal in the normoganglionic small intestinal segment of congenital aganglionosis in rats. The reactivity was also strong in the ganglia of the large intestine of normal rats. Because the proto-ret is preferentially expressed in the neuronal tissue and plays a critical role in differentiation of apparently multipotential neural crest cells to enteric neurons, the results suggest that abnormal development of local vagal neural crest cells, which were influenced by spatially regulating factors, results in the hypoganglionic segment.

Expression of S100 beta in sensory and secretory cells of the vertebrate inner ear

We evaluated anti-S100 beta expression in the chick (Gallus domesticus) inner ear and determined that: 1) the monomer anti-S100 beta is expressed differentially in the vestibular and auditory perikarya; 2) expression of S100 beta in the afferent nerve terminals is time-related to synapse and myelin formation; 3) the expression of the dimer anti-S100 alpha alpha beta beta and monomer anti-S100 beta overlaps in most inner ear cell types. Most S100 alpha alpha beta beta positive cells express S100 beta, but S100 beta positive cells do not always express S100 alpha alpha beta beta. 4) the expression of S100 beta is diffused over the perikaryal cytoplasm and nuclei of the acoustic ganglia but is concentrated over the nuclei of the vestibular perikarya. 6) S100 beta is expressed in secretory cells, and it is co-localized with GABA in sensory cells. 7) Color thresholding objective quantitation indicates that the amount of S100 beta was higher (mean 22, SD +/- 4) at E19 than at E9 (mean 34, SD +/- 3) in afferent axons. 8) Moreover, S100 beta was unchanged between E11-E19 in the perikaryal cytoplasm, but did change over the nuclei. At E9, 74%, and at E21, 5% of vestibular perikarya were positive. The data suggest that S100 beta may be physically associated with neuronal and ionic controlling cells of the vertebrate inner ear, where it could provide a dual ionic and neurotrophic modulatory function.

Overexpression of a calcium-binding protein, S100 beta, in astrocytes alters synaptic plasticity and impairs spatial learning in transgenic mice

Recent evidence suggests that slowly propagating Ca2+ waves from astrocytes can modulate the function of neurons. Altering astrocytic calcium processes in vivo may therefore affect neuronal and behavioral phenotypes. Previously, we generated transgenic mice that overexpress an astrocytic calcium-binding protein, S100 beta. Immunocytochemistry and in situ hybridization showed elevated expression in the astrocytes of the hippocampus and other brain regions. Neurons in the hippocampus were negative for S100 beta. In this paper we analyze the hippocampal electrophysiology and learning properties of mice from two transgenic lines. Significant differences were found between the hippocampal slices of normal and transgenic mice in their response to high frequency (100 Hz) stimulation. The overall distribution of post-tetanic excitatory postsynaptic potentials (EPSP) of the slices from the transgenic mice was shifted significantly toward smaller values to a degree that 25% of slices exhibited depression. The altered hippocampal neurophysiology was accompanied by an impairment in a hippocampal-dependent learning task. Transgenic mice showed significant impairment in a spatial version of the Morris water maze, however, they performed normally in non-spatial tasks. Probe trials showed that transgenic mice, though significantly impaired, also acquired spatial information. The results suggested that the impairment was not due to motor dysfunction, impaired vision or motivation of the transgenic mice, findings compatible with a possible hippocampal mechanism. We conclude that overexpression of S100 beta in astrocytes impairs, but does not abolish, the ability to solve a spatial task, and it leads to a significantly decreased post-tetanic potentiation in the hippocampal slice. We hypothesize that the changes are due to calcium mediated processes. Our results support the notion that astrocytes are involved in higher brain functions.

The S100 protein family: history, function, and expression

The S100 family of calcium binding proteins contains approximately 16 members each of which exhibits a unique pattern of tissue/cell type specific expression. Although the distribution of these proteins is not restricted to the nervous system, the implication of several members of this family in nervous system development, function, and disease has sparked new interest in these proteins. We now know that the original two members of this family, S100A1 and S100B, can regulate a diverse group of cellular functions including cell-cell communication, cell growth, cell structure, energy metabolism, contraction and intracellular signal transduction. Although some members of the family may function extracellularly, most appear to function as intracellular calcium-modulated proteins and couple extracellular stimuli to cellular responses via interaction with other cellular proteins called target proteins. Interaction of these proteins with target proteins appear to involve cysteine residues (one in S100A1 and two in S100B), as well as a stretch of 13 amino acids, in the middle of the molecule called the linker region, which connects the two EF-hand calcium binding domains. In addition to the amino acid sequence and secondary structures of these proteins, the structures of the genes encoding these proteins are highly conserved. Studies on the expression of these proteins have demonstrated that a complex mixture of transcriptional and postranscriptional mechanisms regulate S100 expression. Further analysis of the function and expression of these proteins in both nervous and nonnervous tissues will provide important information regarding the role of altered S100 expression in nervous system development, function and disease.

S100 beta protein expression in Alzheimer disease: potential role in the pathogenesis of neuritic plaques

Increased synthesis and release of S100 beta protein from activated astrocytes has been implicated in the overgrowth of dystrophic neurites in neuritic plaques in Alzheimer disease (AD). To evaluate the quantitative relationships between tissues levels of S100 beta and the numbers of neuritic plaques in AD patients, we counted neuritic plaques, by Tau-2 immunoreactive (Tau-2+) labeling, in tissue sections of hippocampus and adjacent temporal cortex and measured the levels of S100 beta protein, by Western immunoblot labeling, in samples of analogous regions from contralateral hemisphere of the same patients. In AD, tissue levels of S100 beta (two- to fivefold that of controls) were significantly correlated with the number of Tau-2+ plaques (R = 0.82, P < .01). Dual-label immunohistochemical analysis showed that most S100 beta+ cells were activated GFAP+ astrocytes. These results were substantiated by a significant correlation between S100 beta and GFAP tissue levels (R = 0.81, P < .05). Many of the S100 beta+ astrocytes were clustered around and within Tau-2+ plaques. Indeed, no Tau-2+ plaques were found without associated activated S100 beta+ astrocytes. Our findings provide further evidence of a role for S100 beta protein in dysregulation of neurons that leads to apparently nonsensical growth of imperfect neurites in AD, a potential key element in early stages of neuritic plaque pathogenesis.

Postnatal development of glial fibrillary acidic protein, vimentin and S100 protein in monkey visual cortex: evidence for a transient reduction of GFAP immunoreactivity

In the cerebral cortex of some species, the gradual appearance of glial fibrillary acidic protein (GFAP) is often interpreted as reflecting the parallel maturation of neuronal connectivity. We studied the postnatal maturation of astrocytes in the primary visual cortex of Callithrix jacchus using antibodies against GFAP, vimentin and S100 protein as immunohistochemical markers. In the cortical grey matter of this species, the overall GFAP-immunoreactivity (IR) as measured by image analysis is high at birth (130% of the adult value), decreases until about 3 months (80%) and increases again towards adult values (100%). Vimentin-IR was high at birth, and declined towards 3 months and later. In contrast, S100-IR augmented postnatally in neuropil, and showed a laminar shift of maximum IR from layer IV to supragranular layers during ontogenesis. The decrease of GFAP-IR is predominantly due to changes in density of GFAP-positive (+) astrocytes within cortical tissue (newborn: 18,600 GFAP+astrocytes/mm3; 1 month: 11,600/mm3; 3 months: 5,700/mm3; adult: 10,200/mm3), while the overall number of astrocytes remained relatively constant as shown by the number of S100-positive astrocytic cell bodies. At times of low GFAP-IR a reduced area density of intermediate filaments was found in astrocytes by electron microscopy. The period of reduced GFAP-expression coincides with the time of prominent synapse remodeling in the visual cortex of marmosets. These data suggest that GFAP-expression may depend on functional conditions rather than time-dependent maturation.

Regional changes in expression of NCAM, GFAP, and S100 in aging rat brain

In aging brain degenerative processes occur. However, the aging brain still have regenerative capacity although diminished compared to young rats. The neural cell adhesion molecule (NCAM) may be involved in neuroplasticity during regenerative events. In this study, the polypeptide composition and amount of NCAM was determined in regions of brain from young, mature and old rats. During adult life, the amount of NCAM decreased in several brain regions whereas in aged rats, NCAM was enhanced in all brain regions examined. The amount of the glial fibrillary acidic protein (GFAP) increased during aging in all brain regions reflecting general gliosis in the aged rat brain. The amount of the neuro- and gliotrophic protein S100 increased from young adult to mature age in all brain regions investigated followed by a decrease during old age. Aged rats were tested in a Morris water maze and a group of rats (20%) with learning impairment was defined. However, no differences in amount of NCAM, GFAP, or S100 were observed between aged rats with and without spatial learning impairment.

Expression and complex formation of S100-like proteins MRP8 and MRP14 by macrophages during renal allograft rejection

MRP8 and MRP14, two S100-like calcium-binding proteins, are expressed during differentiation of monocytes/macrophages. Both assemble to different noncovalently associated complexes that are supposed to represent the biologically active states. The present study was intended to investigate the molecular basis of macrophage heterogeneity with respect to expression and complex formation of MRP8 and MRP14 during acute and chronic rejection of renal allografts. First, specificity of antisera and mAbs to be directed against MRP8, MRP14, or MRP8/MRP14 heterodimers was determined by immunocytochemical and Western blot analyses of L132 fibroblasts (co-)transfected with MRP8 and/or MRP14 cDNA. Then, immunohistochemical analysis of biopsy specimens obtained from kidney allografts after acute rejection was performed, revealing a parallel expression of MRP8 and MRP14 with coincident MRP8/MRP14 heterodimer formation in infiltrating monocytes. In contrast, chronic allograft rejection was characterized by a subpopulation of monocytes defined by the absence of MRP8/MRP14 complex formation despite expression of MRP8 and MRP14 monomers. Double-labeling experiments showed that this was due in part to differential expression of MRP8 and MRP14 in infiltrate macrophages of chronic rejection. The data presented demonstrate for the first time differences in MRP8/MRP14 complex assembly by infiltrating monocytes in situ. These seem to be of pathophysiological relevance since complex formation defines subpopulations of monocytes associated with distinct pathways of immunological reactions. Differences in the mode of calcium-dependent signaling may, therefore, be of importance for understanding the molecular basis of macrophage heterogeneity during acute and chronic allograft rejection.

Experimental gliopathy in the adult rat CNS: effect on the blood-spinal cord barrier

The expression of certain blood-brain barrier (BBB) properties in CNS endothelial cells appear to be dependent on astroglial interactions in vitro. However, evidence for direct astroglial support of BBB function in vivo is controversial. To determine if perivascular astroglial damage or loss would compromise BBB function in situ, localized astroglial degeneration was produced in adult rat spinal cords by systemic injections of the anti-metabolite 6-aminonicotinamide (6-AN). Between 1 and 5 days after 6-AN administration, microvessels in the lumbar spinal cord (blood-spinal cord barrier) were examined for the expression of several BBB markers and for leakage of endogenous and exogenous proteins by means of immunocytochemical and histochemical procedures. Glial cells throughout the gray matter were swollen after 24 h, and by 5 days post-injection perivascular astroglia in laminae VI-VIII appeared completely degenerated. Microvessels were undamaged and continued to express BBB markers such as GLUT-I, gamma-glutamyltranspeptidase, and endothelial barrier antigen in this region in a manner comparable to control animals. These results suggest that differentiated, BBB-competent microvascular endothelia in situ may not depend on continuous astroglial support to maintain these particular BBB characteristics. However, the BBB to protein appeared to be compromised; the gray matter was immunoreactive for serum albumin and some areas were permeable to intravascularly injected horseradish peroxidase (HRP). No increase in microvascular transport vesicles was apparent, and no open, tracer-containing interendothelial junctions were detected using standard ultrastructural methods. Some venous structures were surrounded by hemorrhages and HRP reaction product. Thus, astrocytic injury may alter venous, and possibly microvascular, permeability to macromolecules.

Intraepithelial lymphocyte subpopulations and dendritic accessory cells in normal and hypertrophic adenoids

The adenoids have been studied by immunocytochemistry and electron microscopy in children with and without adenoidal enlargement. Compared with normal adenoids, the enlarged ones showed a marked increase in the number of intraepithelial gamma-delta TCR+ lymphocytes and a slight increase in the number of intraepithelial CD8+ lymphocytes. This was accompanied by large amounts of dendritic human lymphocyte antigen (D related) (HLA-DR+) S-100+ accessory cells in the lymphoid tissue underlying the epithelium. By electron microscopy, dead epithelial cells apposed to intraepithelial lymphocytes, and clefts of the epithelial lamina, could be seen frequently in the enlarged adenoids, whereas, in the normal ones, they could not. Based on these findings, the hypothesis is drawn that imbalance of the system of the intraepithelial cytotoxic lymphocytes may lead to increased killing of epithelial cells and uncontrolled penetration of exogenous agents, and hence be involved in the pathogenesis of adenoidal hypertrophy.

Nimodipine accelerates the postnatal development of parvalbumin and S-100 beta immunoreactivity in the rat brain

The effects of chronic maternal perinatal nimodipine treatment on the immunocytochemical distribution of the Ca(2+)-binding proteins parvalbumin (PV) and S-100 beta in neocortex and hippocampus were studied at the age of postnatal day (PD) 5, 7, 10, 14 and 20. The Ca2+ antagonist nimodipine (1000 ppm BAY e 9736 in daily food) was administered to pregnant rats starting at postconceptual day 11. The expression of PV exemplified in layer V of parietal and retrosplenial cortex and in all hippocampal layers of CA1 and CA3 was enhanced by more than two-fold in the offspring of nimodipine-treated dams at PD 10 compared with placebo-treated animals. The difference was no longer present at PD 14 and 20. Nimodipine administration also significantly increased the number of S-100 beta-immunopositive glial cells in upper neocortical layers I-III at PD 5 and 7. Again, the difference between nimodipine and placebo-treated animals disappeared after PD 10. The data indicate an accelerated development of PV and S-100 immunoreactivity in the postnatal forebrain as a result of perinatal blockade of the L-type Ca2+ current.

Neuro-glial neurotrophic interaction in the S-100 beta retarded mutant mouse (Polydactyly Nagoya). II. Co-cultures study

The homozygote of a mouse strain with genetic polydactyly (Polydactyly Nagoya, Pdn) shows several brain abnormalities, and significant decrease of S-100 beta in the brain [17]. An accompanying paper [18] demonstrates that the hippocampus and caudo-dorsal cortex of homozygote (Pdn/Pdn) mouse were markedly reduced in S-100 beta positive astrocytes and serotonergic fibers, and the content of 5-HT and 5-HIAA of hippocampus and cortex of Pdn/Pdn mouse was lower than those of heterozygote (Pdn/+) or wild type (+/+) mice. To further clarify the effects of target tissues from different type brains on the development of serotonergic neurons, raphe neurons from Pdn/Pdn or +/+ newborn mice were co-cultured with hippocampus or cortex of +/+ or Pdn/Pdn newborn mice. The growth of the serotonergic neurons in the mesencephalic raphe tissue dissociated cultures was estimated by measuring the specific uptake of [3H]5-HT. The development of both genotypes (Pdn/Pdn and +/+) of serotonergic neurons was enhanced by co-cultures with target tissues (hippocampus and cortex) of +/+ brain. This effect was not observed in the co-cultures with Pdn/Pdn brain as a source of target tissue. The present results support the idea that the developmental defect of serotonergic fibers in the Pdn mutant mouse is caused by the deficiency of S-100 beta in the astrocyte of this mutant, and suggest that S-100 beta is a serotonergic growth factor. This mutant mouse is a useful in vivo model to study neural-glial neurotrophic interactions.

Neuro-glial neurotrophic interaction in the S-100 beta retarded mutant mouse (Polydactyly Nagoya). I. Immunocytochemical and neurochemical studies

The homozygote of a mouse strain with genetic polydactyly (Polydactyly Nagoya; Pdn) shows several brain abnormalities, and significant decrease of S-100 beta in the brain. In order to clarify the effects of the retarded production of S-100 beta on the development of monoaminergic neuronal systems and supporting glial cells, immunocytochemical studies of tyrosine hydroxylase (TH), serotonin (5-HT), S-100 beta and glial fibrillary acidic protein (GFAP). In addition, high-performance liquid-chromatography (HPLC) measurements of serotonin and 5-hydroxyindoleacetic acid (5-HIAA) of homozygote (Pdn/Pdn) mouse were examined, and the results were compared with those of other genotypes; heterozygote (Pdn/+) and wild type (+/+) mice. In all types of mice, S-100 beta positive cells and serotonergic fibers were widely distributed throughout the brains and serotonergic cell bodies were located in the brainstem. However, the hippocampus and caudo-dorsal cortex of Pdn/Pdn mouse were markedly reduced in S-100 beta positive cells and in serotonergic fibers. Furthermore, abnormal distribution of GFAP positive cells and fibers were observed in the neocortex and hippocampus of Pdn/Pdn brain. No differences were seen in the distribution of TH neurons or fibers distribution. In the HPLC study, the content of 5-HT and 5-HIAA of the hippocampus and cortex of Pdn/Pdn mouse was lower than those of Pdn/+ and +/+ mice. The present results suggest that the developmental defect of serotonergic fibers in the Pdn mutant mouse is correlate to the deficiency of S-100 beta in the astrocyte of this mutant.

Antigen stimulation alters the expression of S-100 protein in the giant macrophages and follicular dendritic cells of the guinea pig lymph nodes

Injections of chick erythrocytes were employed to examine the relationship between expression of S-100 protein and antigen stimulation in the giant macrophages (GM) and follicular dendritic cells (FDC) of guinea pig lymph nodes by an immunocytochemical method. Popliteal lymph nodes were observed 1, 3, 6 and 12 h, then 1, 2 and 3 days, and finally 1, 2 and 4 weeks after injection of chick erythrocytes into hind foot pads. All GM in control lymph nodes were dendritic in shape at the cortical surface and strongly immunoreactive to S-100 protein. In lymph nodes of injected animals, three types of GM were observed at the cortical surface: cells were S-100-protein-positive/phagocytosis-positive, S-100-protein-positive/phagocytosis-negative and S-100-protein-negative/phagocytosis-positive. GM that were S-100-protein-negative/phagocytosis-positive appeared from 1 h onwards, reaching a maximum number at 6 h and then decreasing in number with time at the cortical surface. In the medulla, such cells were observed after 1 h, increasing to a maximal level at 6 h and, thereafter, gradually decreasing in number. These results indicate that expression of S-100 protein in GM is altered by antigen stimulation and that GM move in the lymph nodes. The same pattern of expression of S-100 protein was demonstrated in the FDC 1 week after injection.