Ettore Nardelli

Complement-Mediated Demyelination in Patients with IgM Monoclonal Gammopathy and Polyneuropathy

We investigated the role of complement in the pathogenesis of the demyelinating polyneuropathy that occurs in some patients with IgM monoclonal gammopathy. Seven patients with chronic sensorimotor polyneuropathy and IgM monoclonal gammopathy were examined. In six patients, the monoclonal protein recognized an epitope shared by myelin-associated glycoprotein and two peripheral-nerve glycolipids, whereas in one patient, IgM bound to an unidentified myelin antigen. Direct and indirect immunofluorescence and immunoperoxidase assays showed colocalization along the myelin sheaths of peripheral-nerve fibers of monoclonal protein with complement components C1q, C3d, and C5. In addition, terminal-complement complex that was not associated with S protein was detected in myelin sheaths. It appeared that alterations in myelin geometry caused by the separation of myelin lamellae corresponded to sites at which terminal-complement complex was deposited. We conclude that demyelination in polyneuropathy associated with IgM monoclonal gammopathy may be mediated by complement.

Use of the Parodi anti-embolism system in carotid stenting: Italian trial results.

PURPOSE To investigate the safety and efficacy of the Parodi anti-embolism system (PAES) in establishing flow reversal in the internal carotid artery (ICA) as a means of protecting against embolic phenomena during carotid stenting. METHODS Seven centers participated in a nonrandomized, prospective trial of carotid angioplasty and stenting under PAES protection in 30 patients (22 men; mean age 72 years, range 49-88) with 15 symptomatic (>70%) and 15 asymptomatic (>80%) stenotic ICAs. Safety was defined as achieving sufficient brain oxygenation during flow reversal as determined by level of awareness and motor control. The presence of new or enhanced neurological deficits and death were endpoints. Performance was based on angiographic evidence of successful retrograde flow. RESULTS The PAES was positioned in all 30 patients, but technical error and access-related difficulties prevented establishment of reversed flow in 2. Among the 28 (93%) patients treated under PAES protection, 1 patient developed aphasia after flow reversal, necessitating balloon deflation between subsequent stages of the procedure. Three other adverse events included 1 case of bradycardia and 2 cases of hypotension, with dysarthria and facial paresis in one and temporary loss of consciousness in the other. All events resolved with appropriate therapy, and there was no change from baseline in the neurological status or brain scans at 24 hours. There were no strokes or neurological deficits at 30 days. CONCLUSIONS The PAES appears to be a safe and effective means of providing protection from embolic complications during carotid stenting.

Experimental induction of myelin changes by anti-MAG antibodies and terminal complement complex

We investigated the role of anti-myelin-associated glycoprotein (MAG) IgM and complement (C) in the pathogenesis of myelin alterations occurring in patients with anti-MAG-associated polyneuropathy. For this purpose, we separately studied the effects of anti-MAG antibodies and terminal C complex (TCC) after injection into the rabbit sciatic nerve. The two different local treatments produced identical ultrastructural abnormalities such as intramyclinic edema, myelin vesiculation and, in particular, separation of the major dense lines with the formation of widely spaced myelin, a peculiar feature encountered in human peripheral nerve disorders with circulating anti-myelin monoclonal IgM. In nerves treated with anti-MAG IgM ultrastructural myelin alterations were concurrent with activation of the rabbits own C to the formation of TCC. Contrary to the immunological and ultrastructural findings obtained in C-sufficient animals, in C6-deficient rabbits injected with anti-MAG IgM no myelin alterations nor C completion were observed. This study identifies anti-MAG IgM as the mediator and the C as the effector of myelin changes observed in the present model and, for extension, in human neuropathies associated with anti-MAG IgM.

Increased Expression of the Normal Cellular Isoform of Prion Protein in Inclusion-Body Myositis, Inflammatory Myopathies and Denervation Atrophy

The cellular isoform of the prion protein (PrPc) is a glycosylphosphatidylinositol‐anchored glycoprotein, normally expressed in neural and non‐neural tissues, including skeletal muscle. In transmissible spongiform encephalopathies, or prion diseases, PrPc, which is soluble in nondenaturing detergent and sensitive to proteinase K (PK)‐treatment, represents the molecular substrate for the production of a detergent‐insoluble and PK‐resistant isoform, termed PrPSc.

T-Cell cytotoxicity of human Schwann cells: TNFα promotes fasL-mediated apoptosis and IFNγ perforin-mediated lysis

The ability of resident cells to induce apoptosis of invading immune cells is a major regulatory factor operating in immune‐privileged tissues, including the nervous system. We investigated the cellular and molecular factors participating in modulation of immune response in peripheral nerves, focusing on two cytotoxic pathways: fas ligand (fasL) and perforin. fasL and perforin expression was found by immunochemistry on Schwann cells (Sc) in nerve biopsies from patients with chronic inflammatory demyelinating polyneuritis and on human Sc cultures. Treatment of Sc with tumor necrosis factor (TNF) α and interferon (IFN) γ upregulated the expression of both molecules. In a coculture model, Sc exposed to TNFα or IFNγ were able to induce both apoptotic and lytic injury of T‐lymphocytes. Inactivation of fasL with the neutralizing antibody NOK‐2 abolished T‐cell apoptosis induced by Sc treated with TNFα, but not by Sc treated with IFNγ. Conversely, T‐cell lysis was significantly decreased when IFNγ‐activated Sc were treated with concanamycin A, which inhibited perforin release. At variance with T‐lymphocytes, B‐cells were less sensitive to cytokine‐treated Sc toxicity. Thus, Sc exposed to inflammatory cytokines have the capacity of inducing selective damage of T‐lymphocytes and have the potential of regulating the immune response in the peripheral nervous system.

Simultaneous occurrence of spongiform encephalopathy in a man and his cat in Italy

follow only simple commands. Repeat EEGs showed periodic triphasic complexes. 2 weeks after admission, he was mute, akinetic, and unable to swallow. He died in early January, 1994. His 7-year-old, neutered, female shorthaired cat presented in November, 1993, with episodes of frenzy, twitching of its body, and hyperaesthesia. The cat was usually fed on canned food and slept on its owner’s bed. No bites from the cat were recalled. In the next few days, the cat became ataxic, with hindquarter locomotor dysfunction; the ataxia got worse and there was diffuse myoclonus. The cat was killed in mid-January, 1994. No pathogenic mutations in the patient’s PrP gene were found. The patient and the cat were methionine homozygous at codon 129. Histology of the patient’s brain showed neocortical and cerebellar neuronal loss, astrocytosis, and spongiosis (figure A). PrP immunoreactivity showed a punctate pattern and paralleled spongiform changes (figure B). The cat’s brain showed mild and focal spongiosis in deeper cortical layers of all four lobes (figure C), vacuolated cortical neurons (figure D), and mild astrogliosis. The cerebellar cortex and the dentate nucleus were gliosed. Immunoreactive PrP showed a punctate pattern in neocortex, allocortex, and caudate nucleus (figure E). Western blot analysis of control and affected human and cat brain homogenates showed 3 PrP bands of 27–35 kDa. After digestion with proteinase K and deglycosylation, only samples from the affected patient and cat showed type-1 PrP, with PrP glycoform ratios comparable to those observed in sporadic CJD (details available from author). This study shows a spatio-temporal association between Simultaneous occurrence of spongiform encephalopathy in a man and his cat in Italy

Systemic passive transfer studies using IgM monoclonal antibodies to sulfatide

We present a patient with benign IgM-gamma anti-Sulfatide (SUL) whose neuropathy was transferred in newborn rabbits. The patients clinico-pathological picture of anti-SUL-associated demyelinating neuropathy is reported. The monoclonal IgM antibodies prepared by Tatums method, that retained their biological activity, were passively transferred to newborn rabbits. The passive transfer produced demyelinating nerve lesions very similar to the donor antibody neuropathy. In experimental lesions we observed the human IgM anti-SUL antibodies binding to Schmidt-Lanterman incisures and nodes of Ranvier. We postulate that the myelin-specific and complement-dependent lesions observed in the peripheral nerve support the potential demyelinating role of anti-SUL antibodies. Moreover, the pattern of the antibody binding to the perineuronal sheath of satellite cells in dorsal root ganglia strengthen the hypothesis that anti-SUL antibodies may have a pathogenetic role in this sensorimotor syndrome.

Gangliosides act as onconeural antigens in paraneoplastic neuropathies

We describe two patients with progressive neuropathy and lung cancer in whom gangliosides (GS) may represent the oncoantigens. Patient 1 had motor neuropathy, high titers of IgG1 and IgG3 to GD1a and GM1, and expansion of circulating gamma-delta T lymphocytes, a T-cell subset responding to glycolipids. Patient 2 presented with Miller-Fisher-like syndrome and IgG3 activity to disialo-GS. In both cases, decreased autoimmune responses and stabilization of neuropathy were accomplished by tumor treatment. By immunohistochemistry, patient 1s IgG bound to his own tumor and to structures of normal nervous system expressing GD1a or GM1. Infiltration of IgG in the same neural structures was found at his autopsy. Regarding cellular immunity, the proportion of gamma-delta T lymphocytes infiltrating carcinoma from patient 1 was significantly higher than in neoplastic controls. These results indicate that GS may represent onconeural antigens in paraneoplastic neuropathy (PNN); their expression on neoplastic tissue may elicit autoimmune responses, which also target neural structures.

Pattern of nervous tissue immunostaining by human anti-glycolipid antibodies

Immunostaining of human, bovine and rodent unfixed nervous tissue sections was performed in order to characterize the structures recognized by anti-glycolipid antibodies. Four human sera from patients, two with M-IgM and motor neuron syndrome or motor neuropathy and two with motor neuropathy and polyclonal IgG antibody activity against gangliosides (GL; i.e. GM1, GD1b, GD1a), were utilized. Serum from a patient with sensory neuropathy and M-IgM immunoglobulins with antibody activity against sulfatide (SUL) was included in this series. This study shows that polyclonal and monoclonal anti-glycolipid antibodies give three different patterns of staining. The first is cholera toxin-like showing a more restricted neuronal pattern of staining. The second is peanut agglutinin-like, which includes the carbohydrate epitope shared by a group of glycoproteins in the gray and white matter. The third (anti-SUL) gives a preferential myelin staining. However, sera with anti-GM1 and anti-SUL antibodies recognize a number of closely situated determinants in the gray matter of the spinal cord and in the granule cells, while in peripheral nerves or in neuronal cells in culture their binding produces a different pattern (nodes of Ranvier for anti-GL; myelin for anti-SUL). These findings indicate that immunohistochemistry with anti-GL and anti-SUL antibodies may provide information regarding the glycolipid-bearing anatomical structures as target antigens and further substantiate the role of these molecules in the pathogenesis of autoimmune neurological disorders.

Anti-heparan sulfate antibodies in neurological disease.

Antibodies to heparan sulfate (HS) have previously been found in association with peripheral neuropathy. We tested sera from patients with neuropathies and with other neurological diseases for antibodies to HS using an avidin‐biotin enzyme‐linked immunosorbent assay (ELISA) system. Increased titers of anti‐HS antibodies were found in 3.4% of patients with neuropathy, and in 3% of patients with other neurological diseases. In all cases, however, an inflammatory disease was present, including chronic inflammatory neuropathy, cerebral vasculitis, or multiple sclerosis. Antibodies to HS appear not to be specific for neuropathy, as they occur in several inflammatory diseases. They might contribute to the associated breakdown of the blood–brain or blood–nerve barrier.