Organisation of the nervous system in the Acoela: an immunocytochemical study

In order to broaden the information about the organisation of the nervous system in taxon Acoela, an immunocytochemical study of an undetermined Acoela from Cape Kartesh, Faerlea glomerata, Avagina incola and Paraphanostoma crassum has been performed. Antibodies to 5-HT and the native flatworm neuropeptide GYIRFamide were used. As in earlier studies, the pattern of 5-HT immunoreactivity revealed an anterior structure composed mainly of commissures, a so-called commissural brain. Three types of brain shapes were observed. No regular orthogon was visualised. GYIRFamide immunoreactive cell clusters were observed peripherally to the 5-HT immunoreactive commissural brain. Staining with anti-GYIRFamide revealed more nerve processes than did staining with anti-FMRFamide. As no synapomorphies were found in the organisation of the nervous system of the Acoela and that of the Platyhelminthes, the results support the view that the Acoela is not a member of the Platyhelminthes. (C) 2001 Harcourt Publishers Ltd.

Basiepidermal nervous system in Nemertoderma westbladi (Nemertodermatida): GYIRFamide immunoreactivity

The Nemertodermatida are a small group of microscopic marine worms. Recent molecular studies have demonstrated that they are likely to be the earliest extant bilaterian animals. What was the nervous system (NS) of a bilaterian ancestor like? In order to answer that question, the NS of Nemertoderma westbladi was investigated by means of indirect immunofluorescence technique and confocal scanning laser microscopy. The antibodies to a flatworm neuropeptide GYIRFamide were used in combination with anti-serotonin antibodies and phalloidin-TRITC staining. The immunostaining revealed an entirely basiepidermal NS. A ring lying outside the body wall musculature at the level of the statocyst forms the only centralisation, the

Evolution of the nervous system in Paraphanostoma (Acoela)

According to recent molecular studies, the Acoela are the earliest extant bilaterian group. Their nervous system displays a striking variety of patterns. The aim of the present investigation was to study the variability of the nervous system in a monophyletic group of the Acoela. Six species of Paraphanostoma were chosen for the study. Using immunocytochemical methods and confocal scanning laser microscopy, the immunoreactive patterns of serotonin (5-HT) and the neuropeptide GYIRFamide were described in detail. The study has demonstrated that the brains in Paraphanostoma species, although diverse in detail, still follow the same general pattern. 18S rDNA sequences were used to generate a hypothesis of the phylogeny within the group. Characters of the nervous system revealed in this study were coded and analysed together with 18S rDNA data. Several synapomorphies in the nervous system characters were identified. However, numerous parallelisms in the nervous system evolution have occurred. Data obtained demonstrate that the genus Paraphanostoma is closely related to Childia and should belong to the same family, Childiidae.

High MMP-9 activity characterizes pleural tuberculosis correlating with granuloma formation

Tuberculosis (TB) pleural disease is complicated by extensive tissue destruction. Matrix metalloproteinase (MMP)-1 and -9 are implicated in immunopathology of pulmonary and central nervous system TB. There are few data on MMP activity in TB pleurisy. The present study investigated MMP-1, -2 and -9 and their specific inhibitors (tissue inhibitor of metalloproteinase (TIMP)-1 and -2) in tuberculous effusions, and correlated these with clinical and histopathological features. Clinical data, routine blood tests, and pleural fluid/biopsy material were obtained from 89 patients presenting with pleural effusions in a TB-endemic area. MMP-1, -2 and -9 were measured by zymography or western blot, and TIMP-1 and -2 by ELISA. Pleural biopsies were examined microscopically, cultured for acid–alcohol fast bacilli and immunostained for MMP-9. Tuberculous pleural effusions contained the highest concentrations of MMP-9 compared with malignant effusions or heart failure transudates. MMP-9 concentrations were highest in effusions from patients with granulomatous biopsies: median (interquartile range) 108 (61–218) pg·mL-1 versus 43 (12–83) pg·mL-1 in those with nongranulomatous pleural biopsies. MMP-1 and -2 were not upregulated in tuberculous pleural fluid. The ratio of MMP-9:TIMP-1 was significantly higher in TB effusions. Tuberculous pleurisy is characterised by a specific pattern of matrix metalloproteinase-9 upregulation, correlating with the presence of granulomas and suggesting a specific role for matrix metalloproteinase-9 in inflammatory responses in tuberculous pleural disease.

The human prion protein residue 129 polymorphism lies within a cluster of epitopes for T cell recognition.

T cell immune responses to central nervous system-derived and other self-antigens are commonly described in both healthy and autoimmune individuals. However, in the case of the human prion protein (PrP), it has been argued that immunologic tolerance is uncommonly robust. Although development of an effective vaccine for prion disease requires breaking of tolerance to PrP, the extent of immune tolerance to PrP and the identity of immunodominant regions of the protein have not previously been determined in humans. We analyzed PrP T cell epitopes both by using a predictive algorithm and by measuring functional immune responses from healthy donors. Interestingly, clusters of epitopes were focused around the area of the polymorphic residue 129, previously identified as an indicator of susceptibility to prion disease, and in the C-terminal region. Moreover, responses were seen to PrP peptide 121-134 containing methionine at position 129, whereas PrP 121-134 [129V] was not immunogenic. The residue 129 polymorphism was also associated with distinct patterns of cytokine response: PrP 128-141 [129M] inducing IL-4 and IL-6 production, which was not seen in response to PrP 128-141 [129V]. Our data suggest that the immunogenic regions of human PrP lie between residue 107 and the C-terminus and that, like with many other central nervous system antigens, healthy individuals carry responses to PrP within the T cell repertoire and yet do not experience deleterious autoimmune reactions.

A Novel Selective Muscarinic Acetylcholine Receptor Subtype 1 Antagonist Reduces Seizures without Impairing Hippocampus-Dependent Learning

Previous studies suggest that selective antagonists of specific subtypes of muscarinic acetylcholine receptors (mAChRs) may provide a novel approach for the treatment of certain central nervous system (CNS) disorders, including epileptic disorders, Parkinson's disease, and dystonia. Unfortunately, previously reported antagonists are not highly selective for specific mAChR subtypes, making it difficult to definitively establish the functional roles and therapeutic potential for individual subtypes of this receptor subfamily. The M 1 mAChR is of particular interest as a potential target for treatment of CNS disorders. We now report the discovery of a novel selective antagonist of M-1 mAChRs, termed VU0255035 [N-(3-oxo-3-(4-(pyridine-4-yl)piperazin-1-yl)propyl)benzo[c][1,2,5]thiadiazole-4-sulfonamide]. Equilibrium radioligand binding and functional studies demonstrate a greater than 75-fold selectivity of VU0255035 for M-1 mAChRs relative to M-2-M-5. Molecular pharmacology and mutagenesis studies indicate that VU0255035 is a competitive orthosteric antagonist of M-1 mAChRs, a surprising finding given the high level of M-1 mAChR selectivity relative to other orthosteric antagonists. Whole-cell patch-clamp recordings demonstrate that VU0255035 inhibits potentiation of N-methyl-D-aspartate receptor currents by the muscarinic agonist carbachol in hippocampal pyramidal cells. VU0255035 has excellent brain penetration in vivo and is efficacious in reducing pilocarpine-induced seizures in mice. We were surprised to find that doses of VU0255035 that reduce pilo-carpine-induced seizures do not induce deficits in contextual freezing, a measure of hippocampus-dependent learning that is disrupted by nonselective mAChR antagonists. Taken together, these data suggest that selective antagonists of M-1 mAChRs do not induce the severe cognitive deficits seen with nonselective mAChR antagonists and could provide a novel approach for the treatment certain of CNS disorders.

A role for the enteric nervous system in the response to helminth infections

The enteric nervous system (ENS) in the gut contains a particularly high concentration of nerve cells, and effectively functions as an independent 'minibrain'. Interactions between nerve, endocrine, immune and other cell types allow the sophisticated regulation of normal gut physiology. They can also bring about a co-ordinated response to parasitic infection, possibly leading to expulsion of the parasite. In this review, Derek McKay and Ian Fairweather will consider, in brief, data pertaining to changes in the ENS following intestinal helminth infections and speculate on the role that these alterations may have in the expulsion of the parasite burden and the putative ability of the parasite to modulate these events.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF PEPTIDERGIC AND SEROTONINERGIC COMPONENTS IN THE ENTERIC NERVOUS-SYSTEM OF THE ROUNDWORM, ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

The localization and distribution of neuropeptides and an indoleamine (serotonin or 5-hydroxytryptamine) in the enteric nervous system (ENS) of the pig roundworm, Ascaris suum, have been determined by the application of an indirect immunofluorescence technique in conjunction with confocal scanning laser microscopy. Whole-mount preparations of pharyngeal, intestinal and rectal regions were screened with antisera to 23 vertebrate peptides, 2 invertebrate peptides and serotonin(= 5-HT). Positive immunoreactivity (IR) was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), FMRFamide, gastrin and serotonin. The only IR observed in the ENS was that evident in the nerve supply to the pharynx and rectal region; no IR was associated with any region of the intestine. The most extensive patterns of IR occurred with antisera to PW, FMRFamide and serotonin. In the pharyngeal component of the ENS, IR was evident in the lateral and dorsal longitudinal pharyngeal nerves, pharyngeal commissures, nerve plexus, and associated nerve cells and fibres. In contrast, the distribution of IR to the PP and gastrin antisera was more restricted and displayed a lower intensity of immunostaining. The other component of the ENS, the rectal enteric system, only yielded immunostaining to FMRFamide. The possible role of neuropeptides and serotonin in the nutritional biology of nematodes is discussed.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF NEUROPEPTIDES IN THE PERIPHERAL NERVOUS-SYSTEM OF THE ROUNDWORM ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

The localisation and distribution of neuropeptides in the peripheral nervous system of the pig roundworm Ascaris suum have been determined by an indirect immunofluorescence technique in conjunction with confocal microscopy. Of the 31 antisera tested, immunostaining was obtained only with antisera to peptide YY (PYY), pancreatic polypeptide (PP) and FMRFamide. Immunostaining for PYY and FMRFamide was evident in the amphidial and papillary ganglia associated with the anterior nerve ring and in the nerves from these ganglia that terminated in sensory receptors within the buccal lips of the parasite. The only peptide immunoreactivity (IR) observed in the reproductive system of either sex was that evident in the nerve supply to the distal region of the vagina in the female worm. It took the form of a well-developed plexus of parallel nerve fibres, cross-connectives and looped commissures. The nerve net diminished in the more proximal region of the vagina. PP-IR was less intense than that for PYY and FMRFamide and was more restricted in distribution, being confined to a small number of nerve fibres in the nerve supply to the vagina; it did not occur in the nerves supplying the anterior sensory receptors. The possible roles of neuropeptides in the sensory and reproductive biology of nematodes are discussed.

IMMUNOREACTIVITY TO 2 SPECIFIC REGIONS OF CHROMOGRANIN-A IN THE NERVOUS-SYSTEM OF ASCARIS-SUUM - AN IMMUNOCYTOCHEMICAL STUDY

Antisera to a highly conserved region of chromogranin A (sequence KELTAE) and to a hexapeptide (sequence KGQELE) adjacent to the putative C-terminus of pancreastatin, a peptide whose sequence is found within the chromogranin A molecule, have been used to examine the localisation of immunoreactivity (IR) to these peptides in Ascaris suum. IR to both peptides was found in the nerve rings and nerve cords. In addition, KGQELE-IR was also observed in the pharyngeal neurones and in a network of fibres on the surface of the female gonoduct. The staining was specific in that it could be abolished by preincubation of the antisera with the appropriate antigen. The two antisera appeared to be staining different subsets of neurones, suggesting that (at least) two peptides were being recognised. The widespread distribution of IR to both peptides throughout the nervous system of the parasite suggests that the peptides carrying the epitopes recognised by the antisera are of fundamental importance to the functioning of the parasite's nervous system.