Characterization of the progressive neuroaxonal dystrophy and subsequent gait abnormalities in the Hspa8V95E knock-in rats.

Neuroaxonal dystrophy (NAD) is a neurodegenerative disease characterized by spheroid (swollen axon) formation in the nervous system. In the present study, we focused on a newly established autosomal recessive mutant strain of F344-kk/kk rats with hind limb gait abnormalities and ataxia from a young age. Histopathologically, a number of axonal spheroids were observed throughout the central nervous system, including the spinal cord (mainly in the dorsal cord), brain stem, and cerebellum in F344-kk/kk rats. Transmission electron microscopic observation of the spinal cord revealed accumulation of electron-dense bodies, degenerated abnormal mitochondria, as well as membranous or tubular structures in the axonal spheroids. Based on these neuropathological findings, F344-kk/kk rats were diagnosed with NAD. By a positional cloning approach, we identified a missense mutation (V95E) in the Hspa8 (heat shock protein family A (Hsp70) member 8) gene located on chromosome 8 of the F344-kk/kk rat genome. Furthermore, we developed the Hspa8 knock-in (KI) rats with the V95E mutation using the CRISPR-Cas system. Homozygous Hspa8-KI rats exhibited ataxia and axonal spheroids similar to those of F344-kk/kk rats. The V95E mutant HSC70 protein exhibited the significant but modest decrease in the maximum hydrolysis rate of ATPase when stimulated by co-chaperons DnaJB4 and BAG1 in vitro, which suggests the functional deficit in the V95E HSC70. Together, our findings provide the first evidence that the genetic alteration of the Hspa8 gene caused NAD in mammals.

Objective To evaluate the expression and significance of Beclin-1 and microtubule-associated protein 1 light chain 3 ( MAPLC3 ) in nucleus pulpous of rats during the aging process. Methods The models of youth, middle-aged and old rats were made with the 3-month, 12-month and 24-months SD rats respectively. The grades of intervertebral disc degeneration were measured with HE staining. The expression of autophagosome in nucleus pulpous was detected under a transmission electron microscope ( TEM ). The changes of Beclin-1 and MAPLC3 in nucleus pulpous were assayed by immunocytochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Results The aging process of rats may reflect the process of intervertebral disc degeneration. There was expression of autophagosome in nucleus pulpous in every group. Beclin-1 and MAPLC3 were expressed in nucleus pulpous cells in each group ( ayerage absorbance values were 0. 42 ± 0. 05, 0. 47 ± 0. 06, 0. 52 ± 0. 05 and 0. 34 ± 0. 06, 0. 39 ± 0. 05,0. 46 ±0. 09 respectively) and both of them were higher in old group (P <0. 01 ). Beclin-1 and MAPLC3 mRNA was expressed in nucleus pulpous in each group (0.86 ±0. 12, 0.93 ±0. 14, 1.01 ±0. 13 and 1.09 ± 0.06,1.15 ± 0. 07, 1.33 ± 0. 11 respectively) and both of them were higher in old group ( P <0. 05 and P < 0. 01 respectively). Conclusion Autophagy resides in the process of intervertebral disc degeneration. The expression of MAPLC3 and Beclinl was up-regulated in nucleus pulpous in different groups and autophagy. Up-regulation of MAPLC3 and Beclinl may be related to the process of the lumbar disc degeneration. Key words: Intervertebral disc degeneration; Aging; Autophagy; Beclin-1; MAPLC3

Neuroaxonal dystrophy (NAD) was examined in two Papillon dogs and a mix breed dog between Papillon and Chihuahua. In addition, cerebellar cortical abiotrophy (CCA) in a Papillon dog, which had similar clinical and magnetic resonance imaging (MRI) features to those of NAD, was also investigated. The common clinical symptoms of all dogs affected with NAD and CCA, were pelvic limb ataxia and cerebellar ataxia including intention tremor, head tremor, and hypermetria in the early onset. These clinical signs were progressed rapidly, and two dogs with NAD were euthanized by owner's request and the other two died by aspiration pneumonia. MRI examinations and gross observations at necropsy revealed moderate to severe cerebellar atrophy in all cases of NAD and CCA. The most typical histological change of NAD was severe axonal degeneration with marked spheroid-formation in the dorsal horn of the spinal cords, the nuclei gracilis, cuneatus, olivalis and its circumference in the medulla oblongata. The spheroids were characterized as large eosinophilic or granular globes within the enlarged myelin sheaths, sometimes accompanied by moderate accumulation of microglias and/or macrophages. In contrast, such spheroid formation was minimal in the brain of CCA. In the cerebellum, mild to moderate loss of the Purkinje and granular cells were recognized in three dogs with NAD, whereas these changes were more prominent in a dog with CCA. Although the clinical signs and MRI findings relatively resembled between NAD and CCA, the histopathological features considered to be quite differ, suggesting distinct pathogenesis and etiology. Since both NAD and CCA are proposed as the autosomal recessive hereditary disorders, careful considerations might be needed for the breeding of Papillon and Chihuahua dogs.

Introduction: In spite of significant progress in breast cancer research, hormonal therapy resistant triple negative breast cancers (TNBC) still pose a greater therapeutic challenge due to lack of a suitable therapeutic target and their resistance to apoptosis induced by chemotherapy. Therefore, alternative approaches are required to induce cell death in these apoptosis-resistant breast cancers. We previously showed that certain sulfhydryl reactive compounds, containing α,β-unsaturated ketones, such as 15d-PGJ2 induced non-apoptotic and non-autophagic cell death in apoptosis resistant and rapidly growing cancer cells through induction of microtubule-associated protein 1 light chain 3 (MAP1LC3) and sequestosome1 (p62) proteins. Purpose: In the present study, our objective is to address the role of MAP1LC3 in 15d-PGJ2 induced non-apoptotic and non-autophagic cell death of breast cancer cells. Methods: Stable knockdown of endogenous MAP1LC3 expression was achieved by shRNA expression vectors. Cell culture, cell proliferation, soft-agar colony forming assays and immunoblotting were performed using standard methods. Nude mice tumor models were used for in vivo studies. Results: First, we showed the efficacy of 15d-PGJ2 in reducing the breast tumor burden using xenograft mice models of MDA-MB-231 cells by i.p. into tumor bearing mice. We observed significant reduction of tumor growth with high levels of p27, PTEN and less pAkt compared to vehicle treated mice. Most importantly, tumors treated with 15d-PGJ2 showed extensive cytoplasmic vacuoles with remarkable increase in endoplasmic reticulum (ER) stress markers such as Bip, CHOP along with MAP1LC3 and p62 proteins as well as higher molecular weight ubiquitinated proteins. Notably, in normal human mammary epithelial cells (HMEC) 15d-PGJ2 failed to induce cell death as well as MAP1LC3 protein. Likewise, MAP1LC3 knockdown (LC3KD) in MDA-MB-231 breast cancer cells also prevented 15d-PGJ2 induced cell death with decreased accumulation of ER stress markers such as Bip and CHOP, p62 and ubiquitinated proteins. In addition, MAP1LC3 deficiency also resulted in changes in MDA-MB-231 cell morphology from an elongated mesenchymal shape to epithelial cobblestone appearance with distinct slower growth rate. Moreover, LC3KD cells failed to form colonies in soft agar, showed reduced migration and invasion in transit well chamber assays, and expressed high levels of p21, p27 and PTEN with decreased pAkt levels. Finally, MAP1LC3-deficient cells showed marked reduction in tumor growth compared to parental MDA-MB-231 cells in xenograft model using nude mice. Conclusions: Hence our results suggest that the induction of MAP1LC3 in response to treatment with sulfhydryl reactive β, α-unsaturated carbonyl compounds is an essential feature in inducing a novel form of cell death in therapy resistant breast cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2280. doi:1538-7445.AM2012-2280

Neuroaxonal Dystrophy in Man: Character and Natural History.- Neuropathological Conditions Related to Neuroaxonal Dystrophy.- Infantile Neuroaxonal Dystrophy or Seitelberger's Disease: II. Peripheral Nerve Involvement. Electron Microscopy Study in one Case.- How Long Can Degenerating Axons in the Central Nervous System Produce Reactive Changes? An Electron Microscopic Investigation.- Fine Structural Changes of Neurites in Alzheimer's Disease.- Mitochondrial Changes in Axonal Dystrophy Produced by Vitamin E Difficiency.- Permeability of Blood Vessels and Connective Tissue Sheaths in the Peripheral Nervous System to Exogenous Proteins.- Changes in Axonal Flow During Regeneration of Mammalian Motor Nerves.- Nuclear, Cytoplasmic and Axoplasmic RNA in Experimental Neuroaxonal Dystrophy.- The Dependence of Fast Transport in Mammalien Nerve Fibers on Metabolism.- Slow and Rapid Transport of Protein to Nerve Endings in Mouse Brain.- Transport of S-100 Protein in Mammalian Nerve Fibers and Transneuronal Signals.- Dynamic Condition of Protein in Axons and Axon Terminales.- Effect of Nerve Section on Protein Metabolism of Ganglion Cells and Preganglionic Nerve Endings.- Some Observations on the Experimental Production of Acute Neuroaxonal and Synaptosomal Dystrophy.- Independence of the Rapid Axonal Transport of Protein from the Flow of Free Amino Acids.- Acetylcholinesterase in Mammalian Peripheral Nerves and Characteristics of its Migration.- Role of Slow Axonal Transport in Nerve Regeneration.- Axoplasmic Streaming and Proteins in the Retino-Tectal Neurons of the Pigeon.- Different Modes of Substance Flow in the Optic Tract.- A Symmetrical Double-Label Method for Studying the Rapid Axonal Transport of Radioactivity from Labelled d-Glucosamine in the Gold Fish Visual System.- Single Cell Isotope Injection Technique, a Tool for Studying Axonal and Dendritic Transport.- Neuronal Organelles in Neuroplasmic (Axonal) Flow, I. Mitochondria.- Neuronal Organelles in Neuroplasmic (Axonal) Flow, II. Neurotubules.- Axonal Transport of Proteins in the Optic Nerve and Tract of the Rabbit.- Changes in Microtubules and Neurofilaments in Constricted, Hypoplastic Nerve Fibers.- Effects of Vinblastine and Colchicine on Monoamine Containing Neurons of the Rat, with Special Regard to the Axoplasmic Transport of Amine Granules.- The Importance of Axoplasmic Transport of Amine Granules for the Functions of Adrenergic Neurons.- Axonal Transport of Proteins in the Hypothalamo-Neurohypophysial System of the Rat.- Axonal Transport in the Goldfish Visual System.

Clinical, pathological and genetic examination revealed an as yet uncharacterized juvenile-onset neuroaxonal dystrophy (NAD) in Spanish water dogs. Affected dogs presented with various neurological deficits including gait abnormalities and behavioral deficits. Histopathology demonstrated spheroid formation accentuated in the grey matter of the cerebral hemispheres, the cerebellum, the brain stem and in the sensory pathways of the spinal cord. Iron accumulation was absent. Ultrastructurally spheroids contained predominantly closely packed vesicles with a double-layered membrane, which were characterized as autophagosomes using immunohistochemistry. The family history of the four affected dogs suggested an autosomal recessive inheritance. SNP genotyping showed a single genomic region of extended homozygosity of 4.5 Mb in the four cases on CFA 8. Linkage analysis revealed a maximal parametric LOD score of 2.5 at this region. By whole genome re-sequencing of one affected dog, a perfectly associated, single, non-synonymous coding variant in the canine tectonin beta-propeller repeat-containing protein 2 (TECPR2) gene affecting a highly conserved region was detected (c.4009C>T or p.R1337W). This canine NAD form displays etiologic parallels to an inherited TECPR2 associated type of human hereditary spastic paraparesis (HSP). In contrast to the canine NAD, the spinal cord lesions in most types of human HSP involve the sensory and the motor pathways. Furthermore, the canine NAD form reveals similarities to cases of human NAD defined by widespread spheroid formation without iron accumulation in the basal ganglia. Thus TECPR2 should also be considered as candidate gene for human NAD. Immunohistochemistry and the ultrastructural findings further support the assumption, that TECPR2 regulates autophagosome accumulation in the autophagic pathways. Consequently, this report provides the first genetic characterization of juvenile canine NAD, describes the histopathological features associated with the TECPR2 mutation and provides evidence to emphasize the association between failure of autophagy and neurodegeneration.

Neuroaxonal dystrophy (NAD) is a group of inherited neurodegenerative disorders characterized primarily by the presence of spheroids (swollen axons) throughout the central nervous system. In humans, NAD is heterogeneous, both clinically and genetically. NAD has also been described to naturally occur in large animal models, such as dogs. A newly recognized disorder in Miniature American Shepherd dogs (MAS), consisting of a slowly progressive neurodegenerative syndrome, was diagnosed as NAD via histopathology. To describe the clinical and pathological phenotype together with the identification of the underlying genetic cause. Clinical and postmortem evaluations, together with a genome-wide association study and autozygosity mapping approach, followed by whole-genome sequencing. Affected dogs were typically young adults and displayed an abnormal gait characterized by pelvic limb weakness and ataxia. The underlying genetic cause was identified as a 1-bp (base pair) deletion in RNF170 encoding ring finger protein 170, which perfectly segregates in an autosomal recessive pattern. This deletion is predicted to create a frameshift (XM_038559916.1:c.367delG) and early truncation of the RNF170 protein (XP_038415844.1:(p.Ala123Glnfs*11)). The age of this canine RNF170 variant was estimated at ~30 years, before the reproductive isolation of the MAS breed. RNF170 variants were previously identified in human patients with autosomal recessive spastic paraplegia-85 (SPG85); this clinical phenotype shows similarities to the dogs described herein. We therefore propose that this novel MAS NAD could serve as an excellent large animal model for equivalent human diseases, particularly since affected dogs demonstrate a relatively long lifespan, which represents an opportunity for therapeutic trials. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Interaction of the Unc-51-like kinase and microtubule-associated protein light chain 3 related proteins in the brain: possible role of vesicular transport in axonal elongation

Many different degenerative diseases of the canine central nervous system (CNS) have been described involving white matter in various breeds.1–3 These include Afghan Hound myelopathy and a similar disease in Kooiker dogs, globoid cell leukodystrophy of various breeds, oligodendroglial dysplasia in Bullmastiffs, cavitating leukodystrophy of Dalmatians, hound ataxia, leukoencephalomyelopathy of Rottweiler dogs, and myelopathies in Jack Russell and Fox Terriers.4–15 In the Leonberger dog, no degenerative diseases of the nervous system have been described apart from an inherited polyneuropathy.16 This report describes the clinical signs, magnetic resonance imaging (MRI) findings, and neuropathology of a novel neurodegenerative disorder affecting the white matter of brain and spinal cord in 2 Leonberger dogs. A 2.5-year-old female Leonberger dog was referred to the small animal clinic of the Vetsuisse Faculty-Bern with a 1-year history of intermittent and spontaneous knuckling in the thoracic limbs. Three months before presentation, these signs began to worsen and include the thoracic limbs. The ataxia improved transiently after treatment with corticosteroids. On presentation, the bitch showed generalized ataxia and a hypermetric gait of the thoracic limbs with proprioceptive deficits in all limbs. On wheel barrow examination, stiff stilted steps were obvious. The patellar reflex was increased on both sides and a crossed extensor-flexor reflex could be elicited from the pelvic limbs. Spinal reflexes were slightly diminished in the thoracic limbs. Hematology, serum biochemistry, and cerebrospinal fluid (CSF) analysis were within normal limits. MRI of the head and C1–C4 was performed under general anesthesia in dorsal recumbency. Sequences included a sagittal (Time of Repetition [TR] Echo Time [TE] 2,850/125 ms) and transverse (TR/TE 5,958/100 ms) T2-weighted (T2W), a dorsal CSF-suppressing FLAIR-sequence (TR/TE/Time of Inversion 8,031/125/1,900 ms) and transverse (TR/TE 30/15 ms) and dorsal (TR/TE 30/12 ms) T1-weighted (T1W) gradient echoes—each before and after the IV administration of contrast agent (Omniscana; 0.15 mmol/kg BW). Most obvious in transverse T2W images and less so in the FLAIR images was a hyperintense signal intensity within the dorsolateral funiculi of the spinal cord. The lesion was bilaterally symmetrical and extended from C1 to C4, becoming less intense caudally (Fig 1). Both the plain and contrast-enhanced T1W images were unremarkable. Dog 1. Transverse T2W (FSE T2, TR/TE 5,958/100 ms) image at the level of the atlantoaxial joint. Both lateral funiculi of the spinal cord show increased signal intensity (arrows). A male 2-year-old Leonberger dog was presented to the small animal clinic of the Vetsuisse Faculty-Bern with a history of generalized dysmetria of 6 months duration. The signs had worsened progressively over the past several weeks with spontaneous stumbling. Blood biochemistry and hematologic results examined 2 months previous were unremarkable except for serum T4 concentration (1.4 μg/dL; reference range 1.3–3.7 μg/dL) and serum TSH concentration (1.53 ng/mL; reference range 0–0.32 ng/mL) leading to the diagnosis of hypothyroidism. The dog was treated with levothyroxine (20 μg/kg body weight PO q12h) for 2 months. On neurologic examination, the dog had an abnormal gait with severe generalized ataxia, dragging its paws and with intermittent spontaneous knuckling and hypermetria of the thoracic limbs. Spinal reflexes were normal to increased in all limbs. CSF analysis was unremarkable. MRI of the cervical spine (C2–C7) was performed under general anesthesia in dorsal recumbency. Sequences included a sagittal and transverse T2W and a dorsal T1W plain and contrast-enhanced gradient echo. Contrast application was the same and sequence parameters were similar as described for case 1. The only lesions were seen in the dorsolateral funiculi of the C2 segment, were symmetrical and hyperintense on T2, and did not contrast enhance. In both dogs, a neurodegenerative disorder was suspected because of the symmetry of the lesions and the lack of contrast uptake. Leukodystrophy, neuroaxonal dystrophy, axonopathy, and leukoencephalomyelopathy were included in the list of differential diagnoses. Myelitis was considered less likely because of lack of both contrast uptake and signal changes in T1W images. Both dogs were treated with physiotherapy (eg, controlled walking, passive extension and flexion of the limbs, massage), but had to be euthanized because of progressive deterioration of the disease 2 weeks and 5 months later, respectively. Complete necropsies were performed on both dogs shortly after euthanasia. Gross lesions were restricted to the spinal cord and brainstem. These consisted of an opaque and well demarcated, bilaterally symmetrical, whitish discoloration of the lateral columns (Fig 2). However, unilateral lesions or an asymmetrical pattern were observed as well at some levels (lateral corticospinal tract of the thoracic cord in dog 1, lateral corticospinal tract of the cervical and thoracic cord in dog 2). Lesions were most severe in the cervical spinal cord, but could be observed grossly also throughout the thoracic spinal cord and extending rostrally into the pyramidal tracts of the brainstem in both dogs. Brain, spinal cord, and representative tissue samples of internal organs were fixed in 10% neutral-buffered formalin, processed, embedded in paraffin, sectioned at 5 μm, and stained with hematoxylin and eosin (HE). Selected sections of the brain and spinal cord were stained with luxol fast blue HE and modified Bielschowsky stain. Semithin sections from plastic-embedded tissues were stained with toluidine blue. Immunohistochemistry was performed with specific antisera against the 70 kDa subunit of human neurofilament (1: 50, clone 2F11b) and glial fibrillary acidic protein (1: 1,000, polyclonal anti-GFAPb). The LSAB-AECb method was used, resulting in a red immunopositive reaction product at the site of the reaction. Dog 1. Transverse section of the cervical spinal cord. Bilaterally symmetrical foci of whitish and opaque discoloration in the lateral funiculi. Histologically, in both dogs the cervical spinal cord was most severely affected, but lesions extended caudally into the thoracic spinal cord and rostrally into the brain. Lesions were most prominent in the lateral corticospinal tract, but encroached on the dorsal spinocerebellar, rubrospinal, and the lateral spinothalamic tracts. In case 1, lesions were observed also at the periphery of the fasciculus cuneatus in the cervical spinal cord. A subpial rim of white matter was always preserved. In the brain, lesions were confined to specific regions. Most severely affected areas included the cerebrospinal tract, tectospinal tract, pyramidal decussation, pyramids, medial lemniscus, and the spinal tract of the trigeminal nerve at the level of medulla oblongata. Furthermore, lesions were observed in the cerebellar white substance, cerebral peduncles, optic radiation, and optic tract. Lesions were predominantly bilaterally symmetrical, although in some areas a marked asymmetry could be observed (spinal tract of the trigeminus nerve in dog 1, lateral corticospinal tract of the thoracic cord in dog 1, lateral corticospinal tract of the cervical and thoracic cord in dog 2, pyramidal decussation in dog 2). The lesions were not uniform in intensity within certain functional systems (eg, lateral corticospinal tract, spinal tract of the trigeminal nerve in dog 1). The affected areas showed a marked loss of myelin, readily visible in HE-stained sections because of a paler eosinophilic staining of the affected white matter areas. With luxol fast blue-HE staining, the deep blue staining of the normal white matter was replaced by an eosinophilic staining (Fig 3). Myelin loss was replaced by a prominent gliosis with numerous GFAP-positive reactive fibrillary and gemistocytic astrocytes (Fig 4). Microscopically, dilated myelin sheaths often contained gitter cells, and a few scattered swollen axons were observed. However, axonal changes were relatively mild and confined to the areas of severe myelin loss. Furthermore, Bielschowsky stain and immunohistochemistry for neurofilaments revealed numerous preserved axons running through the affected areas (Fig 5). In dog 2, lesions in the spinal tract of the trigeminal nerve and in the spinal cord were accompanied by a few mild lympho-histiocytic cuffs around the vessels. Minimal Wallerian degeneration was observed rostrally and caudally from the lesions in the spinal cord as well as in the central white matter of the brain. Semithin sections essentially confirmed the demyelinating nature of the lesions with myelin phagocytosis and naked axons. Numerous thin myelin sheets indicated remyelination (Fig 6). No lesions were observed in peripheral nerves. Dog 1. Transverse section of the thoracic spinal cord. Bilaterally symmetrical demyelination characterized by loss of deep blue staining of the white matter in the lateral corticospinal, dorsal spinocerebellar, rubrospinal, the lateral spinothalamic tracts, and cuneate tracts. Luxol fast blue—hematoxylin eosin stain. Scale bar = 2 mm. Dog 1. Loss of myelin is replaced by prominent gliosis. Note numerous gemistocytic astrocytes. Hematoxylin and eosin. Scale bar = 30 μm. Dog 1. Numerous intact axons (red) are running through demyelinated areas. Note gemistocytic astrocytes (arrows). Immunohistochemistry for the 70 kDa subunit of neurofilament (LSAB/AEC method). Scale bar = 30 μm. Dog 1. Area of demyelination with numerous thinly myelinated axons indicating remyelination. Semithin section, Toluidine blue. Scale bar = 15 μm. A novel demyelinating disorder in Leonberger dogs is described affecting both sexes. The neurologic deficits can be explained by demyelination caused by slowing or complete blocking of conduction along affected nerve fibers.1 Ataxia was most likely caused by involvement of the general proprioceptive system, including the medial lemniscus and the fasciculus cuneatus.17 Increased extensor tone, crossed extensor reflex, stiff limb protraction, and toe dragging could be explained by the involvement of the lateral corticospinal and rubrospinal tracts. The lesions in the optic system and central trigeminal tracts probably were not severe enough to cause related neurologic signs. Myelin breakdown was the most prominent change, and axons were largely preserved, suggesting a primary demyelination. The few swollen axons were interpreted to be secondary to severe myelin loss. Myelin degenerative disorders can be classified into either dysmyelination (leukodystrophy) or myelinolytic diseases. The former refers to inherited conditions in which myelin synthesis is defective and cannot be maintained.18 The latter is characterized by disintegration of initially normally formed myelin. Although the restricted distribution and the late onset of clinical signs would favor the latter, it remains to be established if the myelin loss in the 2 Leonberger dogs is caused by a dysmyelination (leukodystrophy) or a myelinolytic disorder.18 Therefore, the more general term leukoencephalomyelopathy was chosen to describe this degenerative disorder. The similarity of the history, clinical signs, and pathologic lesions in 2 dogs of the same breed suggests a genetic basis of the disorder, although pedigree analysis of the 2 Leonberger dogs revealed no common ancestors and none of the littermates seemed to be affected as far as we could determine. The disorder described here shows striking clinicopathologic similarities to the leukoencephalomyelopathy described in Rottweilers.10–12 Clinical signs in Rottweilers include, as in the Leonberger dogs, progressive ataxia of all 4 limbs, proprioceptive deficits, and thoracic limb hypermetria. The age of onset in Rottweilers varied between 1.5 and 3.5 years. Furthermore, the type and distribution of lesions are almost identical with only mild variations. In Rottweilers, a genetic basis for the disorder has been suggested because of the familial relationship among the dogs, but the mode of inheritance could not be elucidated.11 The lesions in both breeds are clearly demyelinating. Simultaneous vigorous remyelination suggests that the oligodendrocyte/myelin compartment is not fundamentally destroyed. Rather, myelin sheets are produced but appear to be unstable. Puzzling for a primary demyelinating disease in the Rottweilers and Leonbergers is the restricted distribution of the lesions, seemingly confined to certain functional systems, reminiscent of multisystem degenerations. This suggests that the primary defect is located in neurons or axons, perhaps hampering the intimate interaction between neurons and oligodendrocytes, where neurons fail to provide proper signals for maintaining the myelin sheets. The molecular basis of such axon-myelin relationships during development and after injury has been investigated in recent years.19 The leukoencephalomyelopathy in Rottweilers and Leonbergers would provide an interesting model to study such neuron-myelin interactions. The slowly progressive leukoencephalomyelopathy described here differs from the rapidly progressing hereditary myelopathy in Afghan Hounds and Kooiker dogs, which is restricted to certain segments of the spinal cord and characterized by prominent malacia and microcavitation of the white matter affecting all funiculi.1,4,13 Preserved axons running through the destroyed white matter in Afghan Hound myelopathy indicate a primary myelin degeneration, whereas prominent Wallerian degeneration in the Kooiker dogs is more indicative of axonal disease. Hound ataxia, a progressive myelopathy described in Harrier Hounds, Beagle Hounds, and Foxhounds, and hereditary ataxia of Fox and Jack Russell Terriers all are characterized by primary axonal degeneration, which was not a feature in the Leonberger dogs described here.9,14,15 In conclusion, this novel leukoencephalomyelopathy of Leonberger dogs appears to be a primary demyelinating disorder that has to be included in the differential diagnosis for ataxia in this breed. The inherited polyneuropathy occurring in this breed can be ruled out because of the lack of predominant lower motor neuron signs and abnormalities in the peripheral nerves.16 Compressive lesions and inflammation can be ruled out by imaging and CSF examination, respectively. MRI examination facilitates obtaining an in vivo diagnosis. No similar symmetric hyperintense MRI lesions of the spinal cord of dogs have been reported. In people, T2W hyperintense symmetric lesions of the cervical spinal cord have been associated with cobalamin deficiency (subacute combined degeneration), copper deficiency, Wallerian degeneration, amyotrophic lateral sclerosis, spinocerebellar atrophy, poliomyelitis (affecting mainly gray matter), AIDS myelitis, and multiple sclerosis.20–24 The signal intensity changes are caused by demyelination, Wallerian degeneration, and gliosis.24 Pathologic examination in the 2 cases revealed additional findings in the brain not detected on MRI. At this time, it appears that the disease in Leonberger dogs could be an inherited myelinolytic disorder. Recognition of additional cases and their pedigree analysis in combination with test matings might help to establish the genetic base of the disease. aOmniscan; GE Healthcare AS, Oslo, Norway bDAKO, Glostrup, Denmark

Neuroaxonal dystrophy associated with vitamin E deficiency in two Haflinger horses

Five juvenile pied imperial pigeons (Ducula bicolor) presented with neurological signs including torticollis, ataxia and poor flying ability. All were humanely destroyed and submitted for post-mortem examination. Microscopically, the most significant findings were in the brain and spinal cord. Spheroid formation was evident within the medulla, pons, diencephalon, cortical grey and subcortical white matter, spinal cord white and grey matterand the granular and molecular cell layers of the cerebellum. There was no evidence of associated inflammation. Immunohistochemistry revealed positive labelling within the spheroids for S100 axons and phosphorylated neurofilaments including SMI31, neurofilament cocktail and microtubule-associated protein 2. Transmission electron microscopy confirmed the light microscopical findings of frequent axonal spheroids. These results are consistent with neuroaxonal dystrophy, which has not been described previously in pigeons. This highlights the importance of considering neuroaxonal dystrophy in juvenile birds with neurological signs. A genetic basis is suspected in this group.

A syndrome resembling previously described feline hereditary neuroaxonal dystrophy (FHND) was diagnosed in a litter of cats. The disorder was characterized by a sudden onset of hind limb ataxia that slowly progressed to hind limb paresis and paralysis. The cats were between 6 and 9 months old when clinical signs were first noted. Histologically, there was marked ballooning of axonal processes, with spheroid formation and vacuolation in specific regions of the brain and spinal cord. Some dystrophic axons contained a central periodic acid-Schiff (PAS)-positive core. Neuronal loss and gliosis were seen in certain brain stem nuclei, spinal cord nuclei, and the cerebellum. Ultrastructurally, there was hypomyelination and dysmyelination of affected axons. The PAS-positive core in dystrophic axons corresponded ultrastructurally with accumulations of electron-dense, flocculent, amorphous material. In addition, these axons contained membrane-bound osmiophilic bodies and large nonmembrane-bound vacuoles. The syndrome in this report differs from the previously described FHND in that no inner ear involvement was seen and onset of clinical signs occurred at a later age. In addition, although some of the affected cats did have diluted coat colors, abnormal coat color was not always associated with clinical disease. This disease is similar to juvenile neuroaxonal dystrophy in children and to neuroaxonal dystrophies described in horses, dogs, cattle, and sheep.

Targeting Inflammatory Demyelinating Lesions to Sites of Wallerian Degeneration

Chapter 61 - Mouse Models of Neuroaxonal Dystrophy Caused by PLA2G6 Gene Mutations

Hallervorden-spatz disease and infantile neuroaxonal dystrophy: Clinical characteristics and nosological considerations