Ventrally emigrating neural tube cells migrate into the developing vestibulocochlear nerve and otic vesicle

Virtually all cell types in the inner ear develop from the cells of the otic vesicle. The otic vesicle is formed by the invagination of non-neural ectodermal cells known as the otic placode. We investigated whether a recently described cell population, originating from the ventral part of the hindbrain neural tube known as the ventrally emigrating neural tube (VENT) cells, also contributes cells to the otic vesicle. The ventral hindbrain neural tube cells were labeled with the fluorescent vital dye DiI or replication-deficient retroviruses containing the LacZ gene in chick embryos on embryonic day 2, after the emigration of neural crest from this region. One day later, the labeled cells were detected only in the hindbrain neural tube. Shortly thereafter, the labeled cells began to appear in the eighth (vestibulocochlear) cranial nerve and otic vesicle. From embryonic day 3.5-5, the labeled cells were detected in the major derivatives of the otic vesicle, i.e. the endolymphatic duct, semicircular canals, utricle, saccule, cochlea, and vestibulocochlear ganglion. That the emigrated cells originated from the ventral part of the hindbrain neural tube was confirmed by focal application of DiI impregnated filter paper and with quail chimeras. It is concluded that, in addition to the otic placode cells, the otic vesicle also contains the ventrally emigrating neural tube cells, and that both cell populations contribute to the structures and cell types in the inner ear. It is well known that inductive signals from the hindbrain are required for the morphogenesis of the inner ear. The migration of the hindbrain neural tube cells into the otic vesicle raises the possibility that the inductive effect of the hindbrain might be mediated, at least in part, by the ventrally emigrating neural tube cells and that, therefore, a mechanism exists that involves cells rather than diffusible molecules only.

Expression of CC chemokines and their receptors in the eye in autoimmune anterior uveitis associated with EAE

PURPOSE

To determine the pattern of expression of CC chemokines and their receptors in the eyes of Lewis rats and to establish their role in autoimmune anterior uveitis (AU) associated with experimental autoimmune encephalomyelitis (EAE).

METHODS

EAE/AU was induced in Lewis rats with myelin basic protein in complete Freund's adjuvant (CFA). The rats were scored for the development of clinical EAE and AU. The expression of CCL5/regulated on activation normal T-cell expressed and secreted (RANTES), CCL2/monocyte chemotactic protein (MCP)-1, CCL3/macrophage inflammatory protein (MIP)-1alpha, and CCL4/MIP-1beta and their receptors was examined at the preclinical stage, onset, peak, and recovery by RT-PCR and ELISA. EAE/AU rats were treated with neutralizing polyclonal antibodies against CCL3/MIP-1alpha, CCL4/MIP-1beta, CCL2/MCP-1, and CCL5/RANTES and tested for the suppression of onset of clinical AU and EAE. The control group received normal rabbit IgG at the same dose.

RESULTS

The gene expression of those chemokines was upregulated concurrently with symptom onset of EAE/AU and correlated with the intensity of inflammatory changes in the eye and central nervous system (CNS). The highest expression of CCL4/RANTES, CCL2/MCP-1, and CCL3/MIP-1alpha in the eye was detected at onset of clinical uveitis, whereas CCL4/MIP-1beta was elevated at the peak of AU. The expression of chemokine receptors associated with T-helper (Th)1-type response, CCR1 and CCR5, correlated with their appropriate ligands and was the highest at the peak of AU, whereas CCR2, the receptor for CCL2/MCP-1, was present before the onset of the disease. Treatment of anti-MIP-1beta and anti-MCP-1 significantly delayed the onset and shortened the duration of AU and EAE. Anti-MIP-1alpha treatment had no effect on clinical EAE but inhibited the clinical signs of AU. Although CCL5/RANTES expression was observed during the entire course of the disease, anti-RANTES treatment had no effect on clinical disease progression.

CONCLUSIONS

The data suggest that CCL2/MCP-1, CCL3/MIP-1alpha, and CCL4/MIP-beta contribute to the recruitment of inflammatory cells into the eye and CNS and to disease activity.

Periostin (an osteoblast-specific factor) is expressed within the embryonic mouse heart during valve formation

Periostin was originally isolated as a osteoblast-specific factor that functions as a cell adhesion molecule for preosteoblasts and is thought to be involved in osteoblast recruitment, attachment and spreading. Additionally, periostin expression has previously been shown to be significantly increased by both transforming growth factor beta-1(TGFbeta1) and bone morphogenetic protein (BMP)-2. Likewise the endocardial cushions that form within embryonic heart tube (embryonic day (E)10-13) are formed by the recruitment, attachment and spreading of endocardial cells into the overlying extracellular matrix, in response to secreted growth factors of the TGFbeta and BMP families. In order to determine whether periostin is similarly involved in heart morphogenesis, in situ hybridization and reverse transcription-polymerase chain reaction were used to detect periostin mRNA expression in the developing mouse heart. We show for the first time that periostin mRNA is expressed in the developing mouse embryonic and fetal heart, and that it is localized to the endocardial cushions that ultimately divide the primitive heart tube into a four-chambered heart.

Anti-enolase-alpha autoantibodies in cancer-associated retinopathy: epitope mapping and cytotoxicity on retinal cells

Patients with cancer-associated retinopathy syndrome (CAR), a progressive blinding disease related to retinal degeneration and systemic tumor outside the eye, develop autoantibodies against alpha-enolase. A small percentage of healthy subjects without evident tumor or visual symptoms also possess autoantibody against enolase. In these studies we examined the fine specificity of anti-enolase antibodies derived from patients with CAR and healthy individuals, using synthetic peptides covering the entire sequence of human alpha-enolase. Epitope mapping revealed that three binding regions of enolase within the residues 31-38 (FRAAVPSG), 176-183 (ANFREAMR), and 421-428 (AKFAGRNF) were common for all autoantibodies tested. However, pathogenic sera recognized an additional unique region, the sequence 56-63 (RYMGKGVS). There were also differences in in vitro cytotoxic activities on E1A.NR3 retinal cells and cell-death promoting activities between anti-enolase antibodies of healthy and CAR affected individuals. These studies showed that anti-enolase antibodies from patients with CAR were able to induce apoptotic cell death in E1A.NR3 retinal cells and provided a potential mechanism for retinal degeneration in humans.

Antibodies to recoverin induce apoptosis of photoreceptor and bipolar cells in vivo

Autoantibodies against recoverin are found in the sera of patients with cancer-associated retinopathy (CAR) syndrome. In these studies we examined the effect of anti-recoverin antibodies from the sera of patients with CAR and rat monoclonal antibody on the retinas of Lewis rats. Anti-recoverin autoanti-bodies penetrated into the photoreceptor and bipolar cell layers following intravitreal injection. Their presence in the retina could be detected by immunofluorescence 24 h after injection. At the same time, individual cells undergoing apoptosis were identified throughout photoreceptor and bipolar cell layers using terminal transferase-mediated dUTP nick-end labeling (TUNEL) and electron microscopy. Normal antibodies used in control experiments did not produce TUNEL labeling. At 24 h, DNA fragmentation was confirmed by DNA ladder electrophoresis. At the electron microscopic level, there was clear evidence of cells undergoing apoptotic cell death in the retinas treated with anti-recoverin antibodies. At 24 and 96 h, nuclear chromatin condensation and increased vacuolization of photoreceptor outer segments were observed. An examination of retinas from animals receiving anti-retinal antibodies revealed a loss of 1-2 rows of nuclei in the outer and inner nuclear layers whereas all controls (sham, normal IgG, phosphate buffered saline) showed an unchanged number of nuclei rows. In addition, there was an increase in spacing between the rows of nuclei of the outer nuclear layer in retinas treated with anti- recoverin antibodies, indicating additional cell loss. These studies provide clear evidence that anti-recoverin antibodies are capable of penetrating photoreceptor and bipolar cells, the normal site of recoverin expression in the retina, and that anti-recoverin antibodies produce apoptotic cell death. A similar mechanism may occur in patients with CAR, which may lead to visual loss and blindness.

EAE TCR motifs and antigen recognition in myelin basic protein-induced anterior uveitis in Lewis rats

T cells infiltrating the iris/ciliary body of Lewis rats with anterior uveitis (AU) that had been induced by myelin basic protein (MBP) immunization were previously found to share surface markers common to the T cells that cause experimental autoimmune encephalomyelitis (EAE). To determine whether these AU-associated T cells are in fact the same as those that infiltrate the central nervous system to cause EAE, we examined TCR V gene expression in T cells infiltrating the anterior chamber in rats with AU. As with EAE, we found a biased expression of Vbeta8.2 and Valpha2 in the iris/ciliary body and, although one would expect an influx of nonspecific inflammatory T cells, these biases were still evident at the peak of AU. An analysis of the TCR Vbeta8.2 and Valpha2 sequences derived from the iris/ciliary body demonstrated the presence of the same complementarity determining region 3 motifs found in MBP-specific T cells that are pathogenic for EAE and found in T cells derived from the central nervous system of rats with EAE. Finally, T cells isolated from the iris/ciliary body of rats with AU were found to proliferate in a specific fashion to MBP Ags. Thus, it appears that MBP-specific T cells are pathogenic for AU as well as EAE in the Lewis rat. In addition, the long-term presence of this highly restricted MBP response in the iris/ciliary body indicates that distinct immunoregulatory mechanisms exist in the environment of the eye. This provides an interesting model with which to address questions pertaining to the nature of T cells infiltrating the eye and their regulation during EAE and other systemic diseases.

Similar pattern of MCP-1 expression in spinal cords and eyes of Lewis rats with experimental autoimmune encephalomyelitis associated anterior uveitis

Monocyte chemoattractant protein-1 (MCP-1) is a member of the CC chemokine family responsible for the recruitment of T cells that have been found during inflammation of the spinal cord in experimental autoimmune encephalomyelitis (EAE) in Lewis rats immunized with myelin basic protein (MBP). Lewis rats injected with MBP also developed anterior uveitis (AU), which coincided with the onset of EAE. In the present studies, we examined the expression and distribution of MCP-1 in the eye and spinal cord during disease and compared it to the expression of Th1 cell type cytokines. Initially, MCP-1 expression was detected at the preclinical phase in the iris/ciliary body and lumbar spinal cord and increased during the course of EAE/AU. Mononuclear infiltrating cells and endothelial cells and astrocytes of the CNS could be identified as a source of MCP-1 by in situ hybridization. Kinetics of expression of Th1 characteristic cytokines such as IL-2 and IFNgamma was in agreement with the expression of MCP-1 chemokine. Moreover, induction of the gene expression of MCP-1 seemed to occur earlier than that of MIP-2, and it correlated with increasing disease severity. MCP-1 seems to contribute to the initial recruitment of inflammatory cells into both the tissues of the eye and CNS over the course of disease.

Apoptotic retinal cell death induced by antirecoverin autoantibodies of cancer-associated retinopathy

PURPOSE

Recoverin has been identified as a target autoantigen for antirecoverin antibodies found in the sera of some patients with cancer-associated retinopathy. The aim of this study was to investigate the role of antirecoverin antibodies in cancer-associated retinopathy.

METHODS

Human, rat, and rabbit antirecoverin antibodies were purified using a recoverin-affinity column. Purified biotinylated antibodies were cultured with recoverin-positive rat retinal cells E1A.NR3. Antibody uptake by retinal cells in vitro was analyzed by immunocytochemistry. Cytotoxic effect of antibodies on retinal cells was measured by the MTT colorimetric method. Apoptosis was shown by the ladder DNA fragmentation method and by fluorescent dye chromatin fragmentation analysis.

RESULTS

Antirecoverin antibodies obtained either from sera from five cancer-associated retinopathy patients or from sera of immunized animals were internalized by E1A.NR3 cells. Only specific, antirecoverin antibodies produced destruction of the cells in a dose- and time-dependent manner. Normal immunoglobulin G did not have such effects on retinal cells. No additional cell destruction was observed in the presence of complement as compared with cultures incubated with antirecoverin antibodies alone. Internucleosomal DNA fragmentation and presence of apoptotic cells was observed throughout the culture treated with recoverin specific antibodies but not with normal antibodies. Cells not expressing recoverin (Y79, PC12, and GH3) were not susceptible to cell destruction because of antirecoverin antibody action.

CONCLUSIONS

These studies showed that antibodies specific to recoverin are able to enter and cause death of cells expressing recoverin. In humans, autoantibodies originally elicited against recoverin expressed in tumor cells may damage retinal photoreceptors and play a role in the pathogenesis of cancer-associated retinopathy. Results suggest that autoantibody to recoverin, when given access to recoverin in the retina through the blood-retina barrier, could initiate photoreceptor degeneration leading to blindness. Such mechanism may be common for other paraneoplastic disorders or autoimmune diseases where antibodies interfere with the normal cell physiology.

[Serum levels of sCD23 and IL-4 concentration in stimulated PBMC in children with atopic diseases]

In this study we estimated the correlation between IgE and sCD23 serum levels, and the concentration of IL-4 in PHA-stimulated PBMC cultures in children with atopic diseases. Children with atopic dermatitis showed a high degree of correlation between sCD23-IgE while in the control group no such relationship was found. We also found no relationship between IL-4 and sCD23 in children with atopic asthma, relationship at children with atopic dermatitis, and no relationship in healthy children. Looking for relationship between IL-4 in PHA-stimulated PBMC and IgE serum levels we discovered a weak negative correlation in children with atopic asthma, a highly positive correlation in children with atopic dermatitis and no relationship in the control group.

Myelin basic protein specific T-helper cells induce experimental anterior uveitis

Immunopathological changes in the eyes were examined in Lewis rats after active and passive induction of experimental autoimmune encephalomyelitis (EAE) with myelin basic proteins (MBP) at various stages of EAE. The onset of anterior uveitis (AU) coincided with hind limb paralysis, but uveitis persisted after clinical signs of EAE had subsided. A mild form of uveitis was characteristic for the majority of rats. The changes within the iris and ciliary body consisted of an accumulation of inflammatory cells lining the anterior surface of iris, the trabecular meshwork, and, in some cases, within the ciliary body and the aqueous humor. A similar histopathological picture was observed when rats were injected with the secondary encephalitogenic determinant for Lewis rats, MBP peptide 87-99. Flow cytometry analysis of T cells from the anterior segment of the inflamed eyes after immunization with MBP revealed the presence of CD4+ cells exclusively expressing V beta 8.2 and OX-40 markers. Our data suggest that MBP are encephalitogenic and uveitogenic in Lewis rats and that the V beta 8.2-positive T cells in the eye represent encephalitogenic T cells. Many of those T cells were distributed in the iris and the anterior chamber. These findings indicate that these MBP-specific T cells may play a critical role in EAE as well as in AU.

T-lymphocyte subpopulations (CD4, CD8), IL-4 and IFN-gamma concentration in stimulated cell culture (PBMC) in children with atopic dermatitis

The study was carried out on a group of children with atopic dermatitis. We were looking for a correlation between the percentages of CD4, CD8 lymphocytes and IFN-gamma and IL-4 concentrations in stimulated PHA cells cultures (PBMC). On the ground of obtained results, a statistically significant increase of IL-4 concentration in children with atopic dermatitis and a correlation between CD4 cells and IFN-gamma concentration was found.

Lactoferrin regulates the release of tumour necrosis factor alpha and interleukin 6 in vivo

The effects of bovine lactoferrin on the serum cytokine levels, induced by lipopolysaccharide (LPS) in mice, are described. Bovine lactoferrin (BLF) introduced intravenously, 24 hours before i.v. injection of 50 micrograms of LPS, significantly lowered the serum concentration of TNF-alpha. Doses of BLF lower than 100 micrograms as well as pretreatment of mice with BLF on days 6-2 or 12-2 hours before LPS challenge, were not effective. Moreover, BLF induces by itself a relatively high level of IL-6, peaking at 1 hour following injection. Pretreatment of LPS-injected mice with BLF causes, in addition, a small but statistically significant drop in IL-6 level. Human albumin, used as a control protein, did not cause any changes in the cytokine levels. The data reported herein provide a satisfactory explanation with regard to preventive activity of LF in infection.

Immunostimulatory activity of lactotransferrin and maturation of CD4- CD8- murine thymocytes

Human milk lactotransferrin at a concentration ranging from 1 to 10 micrograms/ml stimulated up to 5 times the humoral immune response to sheep red blood cells, expressed as the number of plaque-forming cells, when injected into mice 3 h before immunization. Further, lactotransferrin-treated thymocytes given intravenously into mice, enhanced the immune response to sheep red blood cells to the same extent as IL-1. In vitro, studies showed that CD4- CD8- thymocytes incubated with lactotransferrin and added to the splenocyte cultures, increased the immune response to sheep red blood cells. Flow cytometry analysis studies indicated that, after an overnight incubation with human lactotransferrin, CD4- CD8- thymocytes acquired the CD4 antigen characteristic for the helper cell phenotype. Taken together, these results suggest that lactotransferrin stimulates the immune response by a process which involves the promotion of T cell differentiation.