Minocycline in leprosy patients with recent onset clinical nerve function impairment.

Nerve function impairment (NFI) in leprosy may occur and progress despite multidrug therapy alone or in combination with corticosteroids. We observed improvement in neuritis when minocycline was administered in patients with type 2 lepra reaction. This prompted us to investigate the role of minocycline in recent onset NFI, especially in corticosteroid unresponsive leprosy patients. Leprosy patients with recent onset clinical NFI (<6 months), as determined by Monofilament Test (MFT) and Voluntary Muscle Test (VMT), were recruited. Minocycline 100mg/day was given for 3 months to these patients. The primary outcome was the proportion of patients with 'restored,' 'improved,' 'stabilized,' or 'deteriorated' NFI. Secondary outcomes included any improvement in nerve tenderness and pain. In this pilot study, 11 patients were recruited. The progression of NFI was halted in all; with 9 out of 11 patients (81.82%) showing ?restored? or ?improved? sensory or motor nerve functions, on assessment with MFT and VMT. No serious adverse effects due to minocycline were observed. Our pilot study demonstrates the efficacy and safety of minocycline in recent onset NFI in leprosy patients. However, larger and long term comparative trials are needed to validate the efficacy of minocycline in leprosy neuropathy.

Serotonin activates overall feeding by activating two separate neural pathways in Caenorhabditis elegans.

Food intake in the nematode Caenorhabditis elegans requires two distinct feeding motions, pharyngeal pumping and isthmus peristalsis. Bacteria, the natural food of C. elegans, activate both feeding motions (Croll, 1978; Horvitz et al., 1982; Chiang et al., 2006). The mechanisms by which bacteria activate the feeding motions are largely unknown. To understand the process, we studied how serotonin, an endogenous pharyngeal pumping activator whose action is triggered by bacteria, activates feeding motions. Here, we show that serotonin, like bacteria, activates overall feeding by activating isthmus peristalsis as well as pharyngeal pumping. During active feeding, the frequencies and the timing of onset of the two motions were distinct, but each isthmus peristalsis was coupled to the preceding pump. We found that serotonin activates the two feeding motions mainly by activating two separate neural pathways in response to bacteria. For activating pumping, the SER-7 serotonin receptor in the MC motor neurons in the feeding organ activated cholinergic transmission from MC to the pharyngeal muscles by activating the Gsα signaling pathway. For activating isthmus peristalsis, SER-7 in the M4 (and possibly M2) motor neuron in the feeding organ activated the G(12)α signaling pathway in a cell-autonomous manner, which presumably activates neurotransmission from M4 to the pharyngeal muscles. Based on our results and previous calcium imaging of pharyngeal muscles (Shimozono et al., 2004), we propose a model that explains how the two feeding motions are separately regulated yet coupled. The feeding organ may have evolved this way to support efficient feeding.

Brain histopathology in red tilapia Oreochromis sp. experimentally infected with Streptococcus agalactiae serotype III.

One of the clinical manifestations of streptococcosis is swimming errors of the infected fish, which is likely caused by lesions in the brain. As most studies described brain histopathology in streptococcosis as meningitis, with a limited description of lesions in the whole brain, the aim of this study was therefore to explore histopathology of the whole brain of red tilapia experimentally infected with Streptococcus agalactiae serotype III. Transcripts relating to motoneuron functions and inflammatory responses were also investigated. In the S. agalactiae-infected fish, the parenchyma of the whole brain and its associated meninx primitiva were found to be markedly infiltrated by mononuclear cells and Gram-positive cocci. Hemorrhage, neuronal necrosis, and localized spongiform histopathology were observed, especially within the midbrain and the cerebellum. The lesion was observed in the medial longitudinal fasciculus and its nucleus. Expressions of the transcripts CD166, GAP43, SMN, and SV2B of the infected fish did not change, while those of IL-1ß and TNF-α were significantly upregulated. It is likely that S. agalactiae cause extensive damage to the fish brain, especially in areas that control swimming activities, through both direct invasion of the bacteria and acute inflammatory responses of the brain resident macrophages, or microglia.

Neuritogenic actions of botulinum neurotoxin A on cultured motor neurons.

Botulinum neurotoxins (BoNTs) are extremely potent neuromuscular poisons that act through soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein cleavage to inhibit neurotransmitter release. The ability of BoNT serotype A (BoNT/A) to eliminate localized transmitter release at extremely low doses is well characterized. In the current study, we investigated the less understood characteristic of BoNT/A to induce nerve outgrowth, sometimes referred to as sprouting. This phenomenon is generally considered a secondary response to the paralytic actions of BoNT/A, and other potential factors that may initiate this sprouting have not been investigated. Alternatively, we hypothesized that BoNT/A induces sprouting through presynaptic receptor activation that is independent of its known intracellular actions on the soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) synaptosomal associated protein of 25 kDa (SNAP-25). To test this, the effects of BoNT/A application on neurite outgrowth were examined using primary cultures enriched with motor neurons isolated from embryonic mouse spinal cord. In this system, BoNT/A potently stimulated neuritogenesis at concentrations as low as 0.01 nM. The neuritogenic effects of BoNT/A exposure were concentration dependent and antagonized by Triticum vulgaris lectin, a known competitive antagonist of BoNT. Similar results were observed with the isolated BoNT/A binding domain, revealing that neuritogenesis could be initiated solely by the binding actions of BoNT/A. In addition, the presence or absence of SNAP-25 cleavage by BoNT/A was not a determinant factor in BoNT/A-induced neuritogenesis. Collectively, these results suggest that binding of BoNT/A to the motor neuronal membrane activates neuritogenesis through as yet undetermined intracellular pathway(s), independent of its known action on vesicular release.

T cell response in acute motor axonal neuropathy.

There is evidence that in the acute axonal motor neuropathy (AMAN) subtype of Guillain-Barré syndrome antibodies to gangliosides, produced through molecular mimicry by antecedent Campylobacter jejuni (C. jejuni) infection, attack gangliosides expressed in human peripheral nerve axolemma, inducing a primary axonal damage. The aim of this study is to investigate whether the T cell response has a role in AMAN pathogenesis. We isolated monocytes from 4 healthy subjects and 5 AMAN patients with antecedent C. jejuni infection and antibodies to GM1 and/or GD1a gangliosides. Immature dendritic cells expressing CD1 molecules cultured with autologous T cells were stimulated with 2 lipopolysaccharides (LPSs) extracted from C. jejuni strains containing GM1 and GD1a-like structures and with GM1 and GD1a. The T cell response to LPSs and to gangliosides was determined by measuring the release of IFN-gamma and TNF-alpha. We observed a T cell response to both LPSs in controls and AMAN patients, whereas only AMAN patients showed T cell reactivity to gangliosides GM1 and GD1a with a tight correlation between T cell reactivity to the ganglioside and individual antibody responses to the same ganglioside. T cells responding to gangliosides were CD1c-restricted CD8 positive and CD27 negative. These findings indicate a contribution of cellular immunity in the pathogenesis of AMAN. A possible role for ganglioside-reactive T cells might be to facilitate the production of antibodies against gangliosides.

Infectious agents and amyotrophic lateral sclerosis: another piece of the puzzle of motor neuron degeneration.

Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative disease affecting motor neurons (MN). This fatal disease is characterized by progressive muscle wasting and lacks an effective treatment. ALS pathogenesis has not been elucidated yet. In a small proportion of ALS patients, the disease has a familial origin, related to mutations in specific genes, which directly result in MN degeneration. By contrast, the vast majority of cases are though to be sporadic, in which genes and environment interact leading to disease in genetically predisposed individuals. Lately, the role of the environment has gained relevance in this field and an extensive list of environmental conditions have been postulated to be involved in ALS. Among them, infectious agents, particularly viruses, have been suggested to play an important role in the pathogenesis of the disease. These agents could act by interacting with some crucial pathways in MN degeneration, such as gene processing, oxidative stress or neuroinflammation. In this article, we will review the main studies about the involvement of microorganisms in ALS, subsequently discussing their potential pathogenic effect and integrating them as another piece in the puzzle of ALS pathogenesis.

Transneuronal transfer of herpes simplex virus type 1 (HSV 1) from mixed limb nerves to the CNS. I. Sequence of transfer from sensory, motor, and sympathetic nerve fibres to the spinal cord.

The time course of transneuronal transfer of Herpes simplex virus type 1 (HSV 1) from sensory, motor, and sympathetic nerve fibres to connected spinal neurones was examined. After injection of a constant number of infectious units into distal forelimb or hindlimb nerves of inbred rats of the same age, the extent of viral transfer was strictly dependent on the survival time postinoculation (p.i.). Retrograde transport to somatic motoneurones occurred at 28-29 hours p.i. (stage 1), in synchrony with anterograde transneuronal transfer via small cutaneous afferents (to laminae I-II). At 36-43 hours p.i. (stage 2), retrograde transneuronal transfer from sympathetic nerve fibres first labelled sympathetic preganglionic neurones. At 48-51 hours p.i. (stage 3), transfer via sensory and sympathetic axons became more extensive, labelling laminae III-IV and other preganglionic neurones. Transneuronal transfer from large muscle afferents and motoneurones (to Clarke's columns and the spinal intermediate zone) occurred only at 66-78 hours p.i. (stage 4). Further increases in distribution (stages 5-6) obtained between 78 and 97 hours p.i. may reflect both specific labelling of second and third order neurones and a gradual local loss of specificity. These results indicate that transfer of HSV 1 occurs through all main classes of peripheral axons, but that both anterograde and retrograde transneuronal transfer from small (unmyelinated and fine myelinated) cutaneous and sympathetic axons precedes transfer from large (myelinated) cutaneous and muscle afferents and motor axons. Analysis of viral transfer at sequential intervals is required to distinguish serially connected neurones, determine the route of labelling, and ensure its specificity.

Correlation between presence of lactate dehydrogenase-elevating virus RNA and antigens in motor neurons and paralysis in infected C58 mice.

Lactate dehydrogenase-elevating virus (LDV) induces poliomyelitis in immunosuppressed C58 mice resulting in fatal paralysis. We have synthesized and cloned cDNA complementary to the LDV genome, and used the cDNA clones as in situ hybridization probes for the detection of LDV RNA in tissue sections. Direct fluorescent antibody staining using IgG from chronically infected mice was used for the detection of LDV antigens. Using these methods, we have detected LDV RNA and antigens in anterior horn neurons of paralyzed mice. The appearance of LDV RNA and antigen positive motor neurons and their location in the spinal cord correlated with the development of paralytic symptoms. No positive neurons were detected in LDV-infected, susceptible mice without signs of paralysis, but some glial cells of the white and gray matter in the spinal cords of these mice were found to contain LDV RNA. These analyses broaden the host cell range of LDV to include neuronal and other cells in the CNS and support the hypothesis of LDV replication in neurons as the cause of poliomyelitis and paralysis.

Retrograde transneuronal transfer of herpes simplex virus type 1 (HSV 1) from motoneurones.

The use of Herpes simplex virus (HSV) as a retrograde transneuronal tracer would have the unique advantage that the virus would be replicated in the second order neurones, resulting in strong labelling. HSV was injected in the XII nerve (mice). The virus was detected immunohistochemically. Four stages in the brainstem distribution of HSV-positive neurones were distinguished. These stages were correlated with injected amounts/survival time. In stage 1, positive neurones were restricted to the XII nucleus; glial cells were present around the intramedullary XII rootlets. In stages 2-4, positive neurones and glial cells were also present outside the XII nucleus: (a) in the lateral reticular formation, Kölliker-Fuse nucleus, raphe and nucleus coeruleus; and (b) in the area around the XII rootlets, including parts of the inferior olive. In view of their distribution, many of the neurones in (a) must have received the virus by retrograde transneuronal transfer from XII motoneurones. The neurones in (b) were probably infected through a different route, i.e. local transfer of virus from XII axons via glial cells. This local transfer does not lead to extensive spread of the infection, yet, when using HSV for retrograde transneuronal tracing it may represent a source of error.

Onuf's motoneuron is resistant to poliovirus.

Onuf's nucleus, located in the anterior horn of the sacral spinal cord, has been shown to innervate the striated muscles of the urethral and anal sphincters and is known to be well preserved in patients who have motoneuron disease. To answer the question whether the nucleus is also safe from motoneurotrophic virus infections, we examined the spinal cords of 3 individuals who had suffered severe poliomyelitis. In 2 of these which were acutely fatal cases, all motoneurons were damaged by neuronophagia, but Onuf's nucleus escaped the inflammatory degeneration. In a chronic case, neuronal loss in the anterior horn with replacement by gliosis was prominent below the thoracic cord down to the sacral cord, but Onuf's nucleus was well preserved. Thus, Onuf's nucleus appears to differ from other motoneurons with regard to susceptibility to poliovirus infection.

Selective vulnerability of neural cells to viral infections.

A number of viruses selectively infect neurons and, in some cases, specific populations of neurons. The susceptible neuron need not be permissively infected to cause acute or chronic disease; therefore, infectious virus may not be recoverable and morphologically identifiable viral structures may not be detectable by ultrastructural structures. Polioviruses and the neurotropic murine retrovirus both cause paralytic disease with major pathological changes in motor neurons of the spinal cord. Both produce disease more readily in later life; in poliovirus because the mature animals are more susceptible to acute infection, and in the neurotropic retrovirus infections because of the long incubation period of the natural infection. In the acute inflammatory poliovirus infections, the motor neurons appear to be selectively infected and lysed by the virus, whereas in the chronic noninflammatory retrovirus infection, the effect may be indirect or may result from nonpermissive infection.

Isolated anterior interosseous nerve palsy following herpes zoster infection: a case report and review of the literature.

A 64-year-old lady noticed weakness of her thumb within two weeks of having developed "shingles" causing vesicular lesions on her arm and hand. Clinical and neurophysiological testing confirmed a lesion of the anterior interosseous nerve. Although motor involvement after herpes zoster infection is recognised, this usually has a myotomal distribution; isolated involvement of a branch of a peripheral motor nerve has not previously been described.

Retrovirus induced motor neuron degeneration.

Neurotropic retroviruses are capable of infecting and altering the function of dividing populations of neuron-like cells such as the PC-12 cell line. However, histological, immunohistochemical, and ultrastructural studies have failed to implicate direct infection of neurons by MuLV as the etiologic mechanism responsible for MuLV induced neurodegenerative disease. Indirect mechanisms such as the physical or biochemical disruption of endothelial cell basement membranes or the production of toxic cytokines by virus infected cells may play a role in the development of retrovirus induced neurodegeneration.

Type 1 human poliovirus binds to human synaptosomes.

Poliovirus is a neurotropic virus that selectively infects human motoneurons in vivo. The basis for the specificity of this infection is not fully understood. It has been suggested that this tropism occurs because motoneurons are the only neurons to express poliovirus receptors. We have examined this hypothesis by measuring the binding of 125I-labeled poliovirus type 1 to neural tissues. With this assay we have detected highly specific binding sites in human but not rodent neural tissue. Regional assays of binding in human central nervous system homogenates demonstrate that binding sites are not confined to motoneurons. Rather, they are widely distributed throughout the human neuraxis. Particularly in the forebrain, binding is more abundant in gray than white matter. For this reason, we performed tissue fractionation studies which indicate that poliovirus binding sites are enriched in synaptosomes, the subfraction of central nervous system gray matter tissue rich in synaptic endings. The preferential expression of poliovirus binding sites in synaptic endings may be an important factor in the motor tropism of this virus, inasmuch as the major category of neurons with synaptic endings outside the central nervous system are motoneurons; thus, particles of virus may preferentially bind to this cell type during poliovirus viremia.

Detection of viral-specific nucleic acid and intracellular virions in ventral horn neurons of lactate dehydrogenase-elevating virus infected C58 mice.

C58 mice which have been immunosuppressed by treatment with cyclophosphamide (200 mg/kg) one day prior to infection with the C strain of lactate dehydrogenase-elevating virus (LDV-C) develop poliomyelitis. Using in situ hybridisation, we found that some ventral horn neurons in these mice contain cytoplasmic viral-specific nucleic acid. Viral-specific nucleic acid was also found within a few small cells located near inflammatory foci. In addition, mature virus particles were observed by electron microscopy in some ventral horn neurons, indicating that these cells are productively infected in C58 mice. Neither viral nucleic acid nor virions were found in the ventral horn neurons of poliomyelitis-resistant mouse strains or C58 mice that were not immunosuppressed prior to infection. Ventral horn neurons which contained viral nucleic acid or virions within cytoplasmic vesicles generally were normal in appearance and were not located within poliomyelitis inflammatory foci. Our data are consistent with the hypothesis that infected neurons first replicate virus and subsequently are attacked and cleared by inflammatory cells.

Herpes simplex virus infection of motor neurons: hypoglossal model.

Herpes simplex virus type 1 (HSV) was inoculated into the tongue muscle of A/J mice. Typical HSV vesicles developed on the tongue surface 4 days after HSV inoculation. Virus was isolated from hypoglossal nerve explants, and inflammatory cells appeared where the hypoglossal nerve exists from the ventral medulla. HSV viral capsids were present in astroglial cells near the point of nerve exit. A focal encephalitis ensued with immunoperoxidase staining of HSV antigens in neurons of the hypoglossal nucleus. These findings indicate that HSV can penetrate the neuromuscular junction, travel in a pure motor nerve, and produce a focal encephalitis in the corresponding central nervous system motor nucleus.