Granuloma, vasculitis, and demyelination in sarcoid neuropathy.

BACKGROUND: Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified. METHODS: We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens. RESULTS: Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients. CONCLUSIONS: Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

Chronic lymphoproliferative disorder of natural killer cells-related neurolymphomatosis with severe autonomic dysfunction: a case report.

BACKGROUND: Chronic lymphoproliferative disorder of natural killer cells (CLPD-NK) is a rare disease characterized by a persistent increase in NK cells in peripheral blood and is generally asymptomatic. If present, symptoms may include fatigue, B symptoms (fever, night sweats, and unintentional weight loss), autoimmune-associated diseases, splenomegaly, and infection due to neutropenia. Peripheral neuropathy, however, is uncommon with an incidence of 3%. Neurolymphomatosis is a neurological manifestation of non-Hodgkin lymphoma and leukemia in which neurotropic neoplastic cells infiltrate the nerves. Moreover, neurolymphomatosis caused by CLPD-NK is extremely rare, with even fewer cases of autonomic dysfunction. We report a case of neurolymphomatosis associated with CLPD-NK and developed autonomic dysfunction, including orthostatic hypotension and gastrointestinal symptoms. CASE PRESENTATION: The patient was a 61-year-old male who was referred to our hospital for leukocytosis. He was diagnosed with CLPD-NK; however, was untreated since he had no hepatosplenomegaly, and other systemic symptoms. He later developed numbness in his lower extremities. Cerebral spinal fluid examination revealed a markedly elevated protein level of 140 mg/dL, and contrast-enhanced magnetic resonance imaging showed bilateral L4 and 5 nerve roots with enlargement and contrast effect. An immune-mediated polyradiculoneuropathy was suspected, and he was treated with intravenous methylprednisolone and immunoglobulin followed by oral prednisolone and cyclosporine. Although his symptoms were relieved by the immunotherapy, significant autonomic dysfunction, including intractable diarrhea, decreased sweating, and orthostatic hypotension, appeared. Additionally, tests for onconeuronal antibodies, ganglionic nicotinic acetylcholine receptor (gAChR) antibody, NF155, CNTN1, Caspr1 antibody, and anti-ganglioside antibodies were all negative. A sural nerve biopsy revealed lymphocytic infiltration, and immunohistochemical staining of lymphocytes confirmed the infiltration of NK and T cells. Therefore, a diagnosis of neurolymphomatosis caused by CLPD-NK was made, and chemotherapy led to partial symptom improvement. CONCLUSIONS: We experienced a case of pathologically diagnosed neurolymphomatosis with autonomic dysfunction associated with CLPD-NK. In cases of subacute to chronic autonomic dysfunction, paraneoplastic neuropathy, amyloidosis, and autoimmune autonomic ganglionopathy are considered; however neurolymphomatosis caused by CLPD-NK, an important cause of autonomic dysfunction, is not. In difficult to make diagnosis, aggressive nerve biopsy is required.

Role of complement components in vasculitic neuropathy associated with systemic lupus erythematosus and rheumatoid arthritis.

INTRODUCTION/AIMS: The mechanism of complement-mediated neurological injury in vasculitic neuropathy associated with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) is unknown. The current study aimed to investigate the local activation of the complement system in vasculitic neuropathy associated with SLE and RA. METHODS: We analyzed sural nerve biopsy specimens collected from patients with SLE (n = 12) and RA (n = 12). The deposition of complement components comprising the classical and lectin pathways was assessed via immunohistochemistry. RESULTS: The disease duration was longer in the RA group than in the SLE group (median [interquartile range]: 11.5 [5.5-31.0] and 4 [2-10] y, respectively). Complement components were found in the epineurial blood vessel walls in patients with SLE and RA, but not in controls. Deposition of the classical pathway component C1q in the blood vessel wall was more commonly observed in the SLE group (71.3% [25.6-85.8]) than in the RA group (20.1% [10.5-35.6]). As for the lectin pathway component, the incidence of ficolin-3 deposition in the blood vessel wall was higher in the SLE group (42.3% [25.7-51.3]) than in the RA group (17.2% [10.3-26.8]). On the contrary, the mannose-binding lectin level was higher in the RA group (37.5% [21.7-51.4]) than in the SLE group (17.8% [11.4-31.0]). DISCUSSION: The classical and lectin pathways of the complement system may be involved in vasculitic neuropathy associated with SLE and RA.

Early ultrastructural lesions of anti-neutrophil cytoplasmic antibody- versus complement-associated vasculitis.

This study aims to describe electron microscopic findings of vasculitis associated with anti-neutrophil cytoplasmic antibody (ANCA) and complement. Sural nerve biopsy specimens were obtained from 10 patients with microscopic polyangiitis (MPA), a representative ANCA-associated vasculitis, and six patients with nonsystemic vasculitic neuropathy (NSVN), who were negative for ANCA but positive for complement deposition. In patients with MPA, attachment of neutrophils to epineurial vascular endothelial cells, migration of neutrophils to the extravascular space via the penetration of the endothelial layer, and release of neutrophil components to the extracellular space were observed. Such neutrophil-associated lesions were not observed in patients with NSVN. Nonetheless, morphological changes in epineurial vascular endothelial cells, such as increases in cytoplasmic organelles and cytoplasmic protrusions into the vascular lumen, were observed in patients with NSVN. Since these findings were observed where light microscopy-based findings suggestive of vasculitis (e.g., the disruption of vascular structures and fibrinoid necrosis) were absent, they were considered early lesions that preceded the formation of the so-called necrotizing vasculitis. In conclusion, this study enabled the visualization of distinctive early ultrastructural lesions associated with ANCA and complement. Further studies are needed to elucidate the molecular basis of the induction of these fine structural changes, which will contribute to the development of targeted therapies based on specific mechanisms of vasculitis.

In vivo visualization of eosinophil secretion in eosinophilic granulomatosis with polyangiitis: An ultrastructural study.

BACKGROUND: Although eosinophilic granulomatosis with polyangiitis (EGPA) has been considered as a single disease entity belonging to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, several studies have suggested that in addition to the mechanisms associated with ANCA, those associated with eosinophils play a vital role in tissue damage. Nevertheless, the morphological bases underlying eosinophil-associated lesions have not been completely elucidated. METHODS: We investigated the electron microscopic findings of sural nerve biopsy specimens obtained from 18 patients with EGPA by focusing on the behavior of eosinophils, particularly the mode of secretion. RESULTS: Eosinophils tended to be located at sites close to endothelial cells within the lumina of epineurial small vessels. Attachment of eosinophils to endothelial cells was observed, particularly at the junction between neighboring endothelial cells, and some of these eosinophils appeared to escape from the vascular lumen to migrate into the extravascular interstitium. Furthermore, we observed eosinophil degranulation via piecemeal degranulation and cytolysis. Degranulating eosinophils were identified in both intravascular and extravascular compartments. Some of the small vessels appeared to be occluded by numerous eosinophils, and eosinophils attached by platelets were also observed, suggesting that coagulopathy occurs in EGPA. CONCLUSIONS: Both extravascular and intravascular eosinophils can induce tissue damage unrelated to classical necrotizing vasculitis associated with ANCA in patients with EGPA. Further research is necessary to elucidate the molecular basis of the induction of these fine structural changes, which will contribute to the development of targeted therapies based on specific mechanisms of eosinophil-related diseases.

Ultrastructural mechanisms of macrophage-induced demyelination in Guillain-Barré syndrome.

OBJECTIVE: To describe the pathological features of Guillain-Barré syndrome focusing on macrophage-associated myelin lesions. METHODS: Longitudinal sections of sural nerve biopsy specimens from 11 patients with acute inflammatory demyelinating polyneuropathy (AIDP) exhibiting macrophage-associated demyelinating lesions were examined using electron microscopy. A total of 1205 nodes of Ranvier were examined to determine the relationship of the macrophage-associated demyelinating lesions with the nodal regions. Additionally, immunohistochemical and immunofluorescent studies were performed to elucidate the sites of complement deposition. RESULTS: Overall, 252 macrophage-associated myelin lesions were identified in longitudinal sections. Of these, 40 lesions exhibited complete demyelination with no association with the lamellar structures of myelin. In 183 lesions, macrophage cytoplasm was located at internodes without association with the nodes of Ranvier or paranodes. In particular, these internodal lesions were more frequent in one patient (152 lesions). In the remaining 29 lesions, the involvement of nodal regions was obvious. Lesions involving nodal regions were more frequently observed than those involving internodes in four patients. Invasion of the macrophage cytoplasmic processes into the space between the paranodal myelin terminal loops and the axolemma from the nodes of Ranvier was observed in three of these patients. Immunostaining suggested complement deposition corresponding to putative initial macrophage-associated demyelinating lesions. CONCLUSIONS: The initial macrophage-associated demyelinating lesions appeared to be located at internodes and at nodal regions. The sites at which the macrophages initiated phagocytosis of myelin might be associated with the location of complement deposition in certain patients with AIDP.

Anti-ganglioside complex antibody profiles in a recurrent complicated case of GQ1b-seronegative miller fisher syndrome and Bickerstaff brainstem encephalitis: a case report.

BACKGROUND: Guillain-Barré syndrome (GBS), Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE) are a group of autoimmune neurological disorders (GBS spectrum disorder) that rarely recur. Recently, anti-ganglioside complex antibodies (GSC-Abs) were identified in patients with GBS spectrum disorder. However, there has been no case report describing GSC-Abs profiles in a recurrent case showing different phenotypes. CASE PRESENTATION: We report the case of a 33-year-old male patient with GQ1b-seronegative BBE-GBS after two prior episodes of MFS-GBS. Our patient showed ophthalmoplegia, ataxia, areflexia and a weakness of the extremities (MFS and GBS symptoms) in all episodes. In the episode reported here, our patient showed disturbed consciousness and an extensor response to cutaneous plantar stimulation was observed (BBE symptoms), with severe disability and requirement for artificial respiration management. GSC-Abs detected in previous episodes were also detected in the subsequent episodes, while new GSC-Abs emerged in each episode. Interestingly, whereas antibodies to GA1/GQ1b and GA1/GT1a, which are commonly identified in patients with GBS, MFS or BBE, appeared in all episodes, antibodies to GD1a/GD1b and GD1b/GT1b, which are predominantly associated with severe disability and the requirement for artificial respiration management in GBS, emerged for the first time in this episode. CONCLUSION: This study reports novel phenomena about the GSC-Abs profiles and its relationship with clinical features in a case with recurrent GBS spectrum disorder, showing different phenotypes in different episodes. Further studies are required to reveal the significance of the GSC-Abs profiles in recurrent GBS spectrum disorder.

Electrodiagnosis of reversible conduction failure in Guillain-Barré syndrome.

INTRODUCTION: In this study we propose electrodiagnostic criteria for early reversible conduction failure (ERCF) in axonal Guillain-Barré syndrome (GBS) and apply them to a cohort of GBS patients. METHODS: Serial nerve conduction studies (NCS) were retrospectively analyzed in 82 GBS patients from 3 centers. The criteria for the presence of ERCF in a nerve were: (i) a 50% increase in amplitude of distal compound muscle action potentials or sensory nerve action potentials; or (ii) resolution of proximal motor conduction block with an accompanying decrease in distal latencies or compound muscle action potential duration or increase in conduction velocities. RESULTS: Of 82 patients from 3 centers, 37 (45%) had ERCF, 21 (26%) had a contrasting evolution pattern, and 8 (10%) had both. Sixteen patients did not show an amplitude increase of at least 50%. CONCLUSION: Our proposed criteria identified a group of patients with a characteristic evolution of NCS abnormality that is consistent with ERCF. Muscle Nerve 56: 919-924, 2017.

Using Xenopus tissue cultures for the study of myasthenia gravis pathogenesis.

Myasthenia gravis (MG), the most common autoimmune disease of neuromuscular junction (NMJ), is heterogeneous in terms of pathophysiology, which is determined by the pathogenic antigen of autoantibodies targeting to synaptic proteins at the NMJs. Currently, patients suspected with MG are routinely screened for the presence of autoantibodies against acetylcholine receptor (AChR) or muscle-specific kinase (MuSK) using a cell-based assay (CBA) that involves the expression of target synaptic membrane protein in heterologous cell lines. However, some autoantibodies may only show reactivity for binding to densely clustered AChR in the physiological conformation, while AChR clustering is known to involve signaling events orchestrated by over a dozen of postsynaptic proteins. To improve the existing serological diagnosis of MG, this study explored the possibility of using the well-established Xenopus primary culture system as a novel CBA for MG. Here, by examining the pathogenic effects of four MG human plasma samples, we found that the samples from both seropositive and seronegative MG patients effectively induced the disassembly of aneural AChR clusters in cultured Xenopus muscle cells, as well as the nerve-induced AChR clusters in the nerve-muscle co-cultures. Importantly, the disassembly of AChR clusters was spatio-temporally correlated to the disappearance of actin depolymerizing factor (ADF)/cofilin, an actin regulator involved in AChR trafficking and clustering. Taken together, this study develops a reliable CBA using Xenopus primary cultures for screening the pathogenicity of human MG plasma samples, and providing a platform for investigating the pathogenic mechanisms underlying the endocytic trafficking and degradation of AChRs at NMJs in MG patients.

Sialylated IgG-Fc: a novel biomarker of chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: Sialylation in Fc portion of IgG plays a crucial role in the pathogenesis of autoimmune diseases and the working mechanism of intravenous immunoglobulin (IVIG). We aim to test whether IgG-Fc sialylation is a biomarker of disease activity for chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: By using specific lectins for sialylation, galactosylation and agalactosylation, lectin-enzyme assay and lectin blotting with pretreatment of IgG degradating enzyme of Streptococcus pyogenes were performed to compare the glycosylation levels of serum IgG-Fc (1) between patients of untreated CIDP (n=107) and normal control subjects (n=27), (2) among patients with untreated CIDP of different clinical severities and (3) before and after IVIG treatment of patients with CIDP (n=12). RESULTS: Sialylation and galactosylation of IgG-Fc were significantly reduced in patients with CIDP than normal control subjects (p=0.003 and 0.033, respectively), whereas agalactosylation was increased in CIDP (p=0.21). Ratios of sialylated/agalactosylated IgG-Fc levels were significantly reduced in CIDP (p<0.001) and inversely related to disease severity (p=0.044). After IVIG treatment, levels of sialylated IgG-Fc significantly increased (p=0.003). CONCLUSIONS: Sialylation of IgG-Fc is reduced in CIDP. Its level correlated with clinical severity and increased after IVIG treatment. Sialylated as well as ratio of sialylated/agalactosylated IgG-Fc could be new measures to monitor the disease severity and treatment status in CIDP.