Bone marrow CD34+/B220+ progenitors target the inflamed brain and display in vitro differentiation potential toward microglia.

Recent evidence indicates that microglial cells may not derive from blood circulating mature monocytes as they express features of myeloid progenitors. Here, we observed that a subpopulation of microglial cells expressed CD34 and B220 antigens during brain development. We thus hypothesized that microglia, or a subset of microglial cells, originate from blood circulating CD34+/B220+ myeloid progenitors, which could target the brain under developmental or neuroinflammatory conditions. Using experimental allergic encephalomyelitis (EAE) as a model of chronic neuroinflammation, we found that a discrete population of CD34+/B220+ cells expands in both blood and brain of diseased animals. In EAE mice, intravenous transfer experiments showed that macrophage-colony stimulating factor (M-CSF) -expanded CD34+ myeloid progenitors target the inflamed central nervous system (CNS) while keeping their immature phenotype. Based on these results, we then assessed whether CD34+/B220+ cells display in vitro differentiation potential toward microglia. For this purpose, CD34+/B220+ cells were sorted from M-CSF-stimulated bone marrow (BM) cultures and exposed to a glial cell conditioned medium. Under these experimental conditions, CD34+/B220+ cells were able to differentiate into microglial-like cells showing the morphological and phenotypic features of native microglia. Overall, our data suggest that under developmental or neuroinflammatory conditions, a subpopulation of microglial cells derive from CNS-invading CD34+/B220+ myeloid progenitors.

Localization of transforming growth factors, TGFbeta1 and TGFbeta3, in hypothalamic magnocellular neurones and the neurohypophysis.

The distribution of transforming growth factor beta (TGFbeta) in the rat and human hypothalamus and neurohypophysis was investigated by immunocytochemical techniques using rabbit polyclonal antisera against TGFbeta(1) and TGFbeta(3). Colocalization of TGFbeta(1) or TGFbeta(3) and arginine vasopressin (AVP) in the rat hypothalamus was studied by double immunolabelling in light microscopy, while their subcellular localization in the rat neurohypophysis was investigated by immunoelectron microscopy. TGFbeta(1) and TGFbeta(3) immunoreactivity was demonstrated in the cell bodies and processes of neurones in the supraoptic nucleus (SON) and paraventricular nucleus (PVN). The TGFbeta-immunoreactive cells were more numerous in the SON compared to the PVN. TGFbeta/AVP double-labelled cells were seen in both nuclei, but some neurones in the SON were labelled for TGFbeta(1) or TGFbeta(3), although not for AVP. In the rat and human neurohypophysis, TGFbeta(3) immunolabelling was more diffuse and stronger than TGFbeta(1) immunolabelling. TGFbeta(1) expression was seen in axonal vesicles and in neurosecretory granules of the axonal endings, while TGFbeta(3) was observed in axonal fibres. Colocalization of TGFbeta(3) or TGFbeta(1) and AVP was observed in some neurosecretory granules, but many were either single-labelled for TGFbeta or AVP or unlabelled. Our results demonstrate, for the first time, the colocalization of TGFbeta and neurohypophysial hormones in magnocellular neurones. We suggest that TGFbeta secreted by the neurohypophysis regulates the proliferation and secretion of certain anterior pituitary cells.

Angulate lysosomes in skin biopsies of patients with degenerative neurological disorders: high frequency in neuronal ceroid lipofuscinosis.

Angulate lysosomes with intralysosomal trilamellar structures were first described in patients with metabolic peroxisomal disorders. In this ultrastructural study of skin biopsies of 139 patients with degenerative neurological disorders and 45 patients with static encephalopathies, we observed angulate lysosomes with similar ultrastructure exclusively in degenerative neurological disorders. They were found in only a few cases (8%), but especially in patients with degenerative metabolic disorders (72%). Because they were never observed in patients with static encephalopathies, angulate lysosomes in the skin would seem to be a sign of progressive encephalopathy. The great majority (75%) of angulate lysosomes were associated with neuronal ceroid-lipofuscinosis (NCL). Their presence in skin biopsy could suggest the diagnosis of NCL and eliminate a peroxisomal disorder. In the latter pathology, angulate lysosomes, numerous in the liver and in the brain, were never observed in the skin. As described in pigmentary retinopathy, a conspicuous feature of NCL, we suggest that in this lysosomal storage disorder, the angulate lysosomes in skin biopsies could result from the phagocytosis of melanin.

In vitro toxic effects of certain antibiotics on the fibroblasts of two children with I-cell disease.

Six antibiotics, pefloxacin (Peflacine), fosfomycin (Fosfocine), teicoplanin (Targocid), vancomycin (Vancocine), ceftazidime (Fortum), piperacillin (Piperilline), that may be used as a systematic coverage during bone marrow transplantation have been tested on dermal fibroblasts of one control subject and two I-cell disease patients, along with five subcultures, corresponding to 5 weeks of culture. The possible toxicity of these molecules was assessed. The evaluation of lysosomal enzyme sphingomyelinase activity, detection of free intracellular cholesterol and the light- and electron-microscopic examination of treated cells were used as measures of metabolic interference and cytotoxicity. Our study shows that despite a lack of any metabolic sign of interference (no modification in enzyme activity, no increase in free intracellular cholesterol), all the antibiotics tested induced a cytotoxic effect which was notably amplified in the I-cell populations. This may be due to the lysosomal lipid storage of these cells which modifies the relationship between the antibiotic and the cell by inducing a different kind of lipid-antibiotic interference.

[Molecular pathology of type 1 primary hyperoxaluria]. / Pathologie moléculaire de l'hyperoxalurie primitive de type 1.

Type 1 is the most common form of primary hyperoxaluria, also called oxalosis when systemic involvement has occurred. This recessive autosomal inherited inborn error of metabolism is characterized by a defect of alanine: glyoxylate aminotransferase (AGT), which is a specific liver enzyme. This protein is responsible for glyoxylate detoxification only when it is located in the peroxisome. The clinical and biochemical phenotypes are neither correlated with the residual catalytic activity of AGT nor with its immunoreactivity. Most patients display less than 2% catalytic activity (enz-) or no immunoreactive protein (crm-); peroxisome-to-mitochondrion mistargeting is the main feature of patients crm+/enz+ or crm+/enz-. The cDNA and genomic DNA have been cloned and sequenced and the gene has been located on the long arm of chromosome 2 in the q36-37 region. Three polymorphisms have been identified which are preferentially associated, leading to two alleles; six point mutations have been currently reported.

Fetal Niemann-Pick disease type C: ultrastructural and lipid findings in liver and spleen.

We present the first ultrastructural study of liver and spleen from a 20-week fetus with Niemann-Pick disease type C in correlation with lipid studies of these tissues. The lipid storage pattern was characteristic of the disease and although the distribution of the lipid storage was similar to that of affected children, ultrastructural studies emphasized that many inclusions were qualitatively different. These are discussed. Concomitant with this complex lipid storage, ultrastructural evidence of cholestasis was observed and the early hyperplasia of pericanalicular microfilaments leads us to question the presence of a toxic metabolite which might induce cholestasis by acting upon microfilaments.

Prenatal diagnosis of Niemann-Pick type C disease: current strategy from an experience of 37 pregnancies at risk.

Thirty-seven pregnancies at risk for Niemann-Pick type C disease were monitored by study of cultured amniotic fluid cells (8 cases) or chorionic villus cells (29 cases) in 23 couples over the period 1984-91. An early protocol combined determination of sphingomyelinase activity with electron microscopy. The current strategy, based on the demonstration of specific abnormalities in intracellular processing of exogenous cholesterol, combines the study of the early phase (first 6 h) of LDL-induced cholesteryl ester formation and the histochemical evaluation (filipin staining after 24 h of LDL uptake) of the LDL-induced accumulation of unesterified cholesterol. Thirteen fetuses were predicted to be affected. Confirmation of the diagnosis was made by study of cholesterol processing in fetal skin fibroblast cultures and/or by demonstration of a characteristic lipid storage in fetal liver, already present at 14 w gestation. Definition of the biochemical phenotype (classical, variant, or intermediate) of the index case, with regard to cholesterol-processing abnormalities, is an absolute prerequisite to adequate genetic counseling in a given family. Prenatal diagnosis has now proved a safe procedure in the predominant (approximately 85%) group of families with the classical phenotype.

Farber disease: an ultrastructural study. Report of a case and review of the literature.

A case of Farber disease is reported and the ultrastructural pathology of the disease is reviewed. The present case showed the typical clinical picture of Farber disease. Acid ceramidase deficiency was demonstrated biochemically. Ultrastructural features of one subcutaneous nodule and a skin biopsy are described. Three lysosomal inclusions characterize Farber disease: curvilinear tubular bodies observed mainly in the reticuloendothelial system, "banana bodies" recorded only in the peripheral nervous system and zebra-like bodies which are essentially a neuronal storage. The nature of each is discussed and the skin biopsy is emphasized for its important diagnostic interest.

[Ultrastructural heterogeneity in primary ciliary dyskinesia syndrome. A case report]. / Hétérogénéité ultra-structurale dans le syndrome de dyskinésie ciliaire primitive. A propos d'une observation.

One of the causes of middle lobe syndrome is primary ciliary dyskinesia. This diagnosis was established in an eight-year-old girl by functional studies of the cilia on bronchial and nasal biopsy specimens. The clinical approach to this disease is emphasized and the technical difficulties raised by the diagnosis are discussed.

[Glomerular nephropathy in the Bardet-Biedl syndrome]. / La néphropathie glomérulaire du syndrome de Bardet-Biedl.

A case of Bardet-Biedl syndrome (BBS) with kidney involvement and renal failure is reported. Light microscopy demonstrates fibrosis of 40% of glomeruli, altered tubules and interstitial fibrosis; no cystic formation is present and immunofluorescence studies are negative. In electron microscopy, the glomerular basement membrane (GBM) looks twisted and uniformly thickened with segmental effacement of the trilaminar architecture; fibrillary material is accumulated close to the inner layer of the GBM. Intermittent peritoneal dialysis is initiated 2 years later; death occurs, after one year of dialysis, due to a bleeding duodenal ulcer. Chronic renal failure seems to be the most frequent cause of death in BBS and several mechanisms are involved. Tubulo-interstitial lesions and renal cysts have been well documented. Glomerular damage with early ultrastructural changes of the GBM may be implicated in the occurrence of renal failure. Further studies are needed to define the incidence and the specificity of the GBM abnormalities in BBS.

Histological, immunofluorescent, and ultrastructural features of lymphogranuloma venereum: a case report.

We studied the course of a case of lymphogranuloma venereum (LGV) over two years. The comparative histological, immunological, and ultrastructural studies showed the existence of characteristic granulations within the macrophages of the granuloma. We suggest that direct immunofluorescence is a specific method for diagnosing cutaneous LGV. Some ultrastructural aspects lead us to believe that different chlamydial bodies exist inside the granuloma.