Paraneoplastic encephalomyelitis: an update of the effects of the anti-Hu immune response on the nervous system and tumour

Paraneoplastic motor disorders

Paraneoplastic neurological disorders (PNDs) are heterogeneous clinicopathologic syndromes that occur throughout the neuraxis resulting from damage to organs or tissues remote from the site of a malignant neoplasm or its metastases. The discordance between severe neurological disability and even an indolent malignancy suggests an underlying neuroimmunologic host immune response that inflicts nervous tissue damage while inhibiting malignant tumor growth. Motor system involvement, like other symptoms and signs, is associated with focal or diffuse involvement of the brain, spinal cord, peripheral nerve, neuromuscular junction or muscle, alone or in combination due to an underlying neuroimmune and neuroinflammatory process targeting neural-specific antigens. Unrecognized and therefore untreated, PNDs are often lethal making early detection and aggressive treatment of paramount importance. While the combination of clinical symptoms and signs, and analysis of detailed body and neuroimaging, clinical neurophysiology and electrodiagnostic studies, and tumor and nervous system tissue biopsies are all vitally important, the certain diagnosis of a PND rests with the discovery of a corresponding neural-specific paraneoplastic autoantibody in the blood and/or spinal cerebrospinal fluid.

Enteric Murine Ganglionitis Induced by Autoimmune CD8 T Cells Mimics Human Gastrointestinal Dysmotility

Inflammatory bowel diseases frequently cause gastrointestinal dysmotility, suggesting that they may also affect the enteric nervous system. So far, the precise mechanisms that lead to gastrointestinal dysmotility in inflammatory bowel diseases have not been elucidated. To determine the effect of CD8 T cells on gastrointestinal motility, transgenic mice expressing ovalbumin on enteric neurons were generated. In these mice, adoptive transfer of ovalbumin-specific OT-I CD8 T cells induced severe enteric ganglionitis. CD8 T cells homed to submucosal and myenteric plexus neurons, 60% of which were lost, clinically resulting in severely impaired gastrointestinal transition. Anti-interferon-γ treatment rescued neurons by preventing their up-regulation of major histocompatibility complex class I antigen, thus preserving gut motility. These preclinical murine data translated well into human gastrointestinal dysmotility. In a series of 30 colonic biopsy specimens from patients with gastrointestinal dysmotility, CD8 T cell-mediated ganglionitis was detected that was followed by severe loss of enteric neurons (74.8%). Together, the preclinical and clinical data support the concept that autoimmune CD8 T cells play an important pathogenetic role in gastrointestinal dysmotility and may destroy enteric neurons.

Synchronous Adie's syndrome and type 1 antineuronal nuclear antibody (anti-Hu)-related paraneoplastic neurological syndromes as predictors of complete response in limited-stage small-cell lung cancer: A case report

Adie's syndrome (AS) and paraneoplastic sensorimotor neuropathy with cerebellar ataxia (PSN CA) are extremely rare, rapidly progressive, autoimmune diseases associated with the development of antibodies against neuronal-specific Hu proteins that are abnormally expressed in small-cell lung cancer (SCLC). We herein present the unique case of a 55-year-old obese woman, previous heavy smoker, who, during treatment with standard cisplatin-etoposide chemotherapy for limited-stage SCLC, developed simultaneous AS and worsening symptoms consistent with PSN CA that led to significant neurological disability and severe axonal electrophysiological pattern on nerve conduction studies. Serology confirmed the presence of low-titre type 1 antineuronal nuclear antibodies (ANNA-1), previously referred to as anti-Hu antibodies. Following plasmapheresis, immunosuppressive therapy and physical rehabilitation, the neurological symptoms progressively improved. The tumour completely regressed, with no recurrence detected on subsequent radiological examinations. The aim of this case was to highlight the importance of a multidisciplinary team approach for early recognition and rapid treatment of paraneoplastic neurological syndromes (PNS) as key to achieving significant recovery and marked improvement of the neurological deficit. This report extends the literature by confirming earlier studies showing that the presence of serum ANNA-1 in SCLC, an aggressive type of pulmonary carcinoma that is challenging to treat, may portend a more favourable prognosis and response to chemotherapy. Thus, patients with SCLC and new-onset neurological symptoms should be tested for ANNA-1. The role of a multimodality approach to treating PNS is also emphasized.

The Roles of Radiotherapy and Immunotherapy for the Treatment of Lymphoma

Lymphoma is rising in incidence and there is a continued need for new and novel therapeutic options. Lymphomas are extremely radiosensitive, but the majority of patients are not candidates for involved field radiation therapy. An intact immune system has a critical role in suppressing lymphomagenesis. Here we discuss the contribution of various components of the immune system in suppressing the development of lymphoma, as elucidated from mouse models. We review the nature of the immune response to lymphoma in non-immunocompromised patients. Finally, we discuss the potential role of immunomodulation, in concert with radiation therapy, as a component of future therapeutic strategies for lymphoma.

Chemotherapy-induced polyneuropathy. Part I. Pathophysiology

Chemotherapy-induced peripheral neuropathy (CIPN) is a toxic neuropathy, a syndrome consisting of highly distressing symptoms of various degrees of severity. It includes numbness of distal extremities, long-term touch, heat, and cold dysaesthesia and, in more severe cases, motor impairment affecting daily functioning. Each form of the syndrome may be accompanied by symptoms of neuropathic stinging, burning, and tingling pain. In the case of most chemotherapeutic agents, the incidence and severity of CIPN are dependent on the cumulative dose of the drug. The syndrome described is caused by damage to the axons and/or cells of the peripheral nervous system.

Chemotherapeutic agents have distinct mechanisms of action in both neoplastic tissue and the peripheral nervous system; therefore, CIPN should not be regarded as a homogeneous disease entity. The present article is an attempt to systematize the knowledge about the toxic effects of chemotherapy on the peripheral nervous system.

Small-cell lung cancer-associated autoantibodies: potential applications to cancer diagnosis, early detection, and therapy

Small-cell lung cancer (SCLC) is the most aggressive lung cancer subtype and lacks effective early detection methods and therapies. A number of rare paraneoplastic neurologic autoimmune diseases are strongly associated with SCLC. Most patients with such paraneoplastic syndromes harbor high titers of antibodies against neuronal proteins that are abnormally expressed in SCLC tumors. These autoantibodies may cross-react with the nervous system, possibly contributing to autoimmune disease development. Importantly, similar antibodies are present in many SCLC patients without autoimmune disease, albeit at lower titers. The timing of autoantibody development relative to cancer and the nature of the immune trigger remain to be elucidated. Here we review what is currently known about SCLC-associated autoantibodies, and describe a recently developed mouse model system of SCLC that appears to lend itself well to the study of the SCLC-associated immune response. We also discuss potential clinical applications for these autoantibodies, such as SCLC diagnosis, early detection, and therapy.

Clinical presentation of immune-mediated cerebellar ataxia

INTRODUCTION

Accumulation of recent clinical evidence indicates that the immune system plays an important role in some central nervous system diseases usually regarded as degenerative. The most striking example is paraneoplastic cerebellar ataxia (PCA), which is characterized by autoimmune cross-reaction between tumoral and nervous system antigens.

STATE OF THE ART

In the past 20 years, several antibodies directed against neuronal and tumoral antigens have been described in association with PCA, leading to the description of different subtypes of PCA based on the associated antibodies, the clinical course and the type of tumor. In some subtypes, cerebellar ataxia occurs in isolation, whereas in others, cerebellar ataxia is a syndrome that occurs in conjunction with extensive nervous system disease. Circulating antibodies have also been described in patients with non-paraneoplastic cerebellar ataxia (N-PCA), suggesting that the immune system may be involved in certain cases of sporadic cerebellar ataxia.

PERSPECTIVE

Immune-mediated cerebellar ataxia does not seem to be limited to paraneoplastic neurological syndromes. Further studies are however necessary to understand the exact pathophysiology of these disorders and offer effective treatments.

CONCLUSION

In this review, the clinical presentation of the different subtypes of potentially immune-mediated PCA and N-PCA will be described, and the associated tumors will be discussed.

Paraneoplastic sensorimotor neuropathy associated with regression of small cell lung carcinoma

An elderly female smoker presented with nausea and anorexia. Imaging and histopathology were consistent with a diagnosis of small cell lung cancer (SCLC). She subsequently developed a progressive sensorimotor neuropathy with high titres of anti-Hu antibodies. Development of the neuropathy was associated with marked regression in the lung neoplasm. Repeat investigation with radioimaging and bronchoscopy showed no evidence of neoplasia. Paraneoplastic sensorimotor neuropathies are commonly associated with SCLC particularly in the presence of anti-Hu antibodies. Regression of SCLC with anti-Hu antibodies has only been reported twice previously. The authors believe this case supports the theory that anti-Hu antibodies confer anti-tumour activity causing tumour regression.

Small cell lung carcinoma presenting with acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease characterised by subcortical high-signal white matter lesions on T2 weighted MRI. It most commonly occurs in children following an acute viral illness. We present a case study in which ADEM was the presenting condition in an adult female with small cell lung carcinoma. We discuss the evidence in the literature suggesting that ADEM may be viewed as a paraneoplastic syndrome.

Chemotherapy-induced neuropathy

Neurotoxic side effects of cancer therapy are second in frequency to hematological toxicity. Unlike hematological side effects that can be treated with hematopoietic growth factors, neuropathies cannot be treated and protective treatment strategies have not been effective. For the neurologist, the diagnosis of a toxic neuropathy is primarily based on the case history, the clinical and electrophysiological findings, and knowledge of the pattern of neuropathy associated with specific agents. In most cases, toxic neuropathies are length-dependent, sensory, or sensorimotor neuropathies often associated with pain. The platinum compounds are unique in producing a sensory ganglionopathy. Neurotoxicity is usually dependent on cumulative dose. Severity of neuropathy increases with duration of treatment and progression stops once drug treatment is completed. The platinum compounds are an exception where sensory loss may progress for several months after cessation of treatment ("coasting"). As more effective multiple drug combinations are used, patients will be treated with several neurotoxic drugs. Synergistic neurotoxicity has not been extensively investigated. Pre-existent neuropathy may influence the development of a toxic neuropathy. Underlying inherited or inflammatory neuropathies may predispose patients to developing very severe toxic neuropathies. Other factors such as focal radiotherapy or intrathecal administration may enhance neurotoxicity. The neurologist managing the cancer patient who develops neuropathy must answer a series of important questions as follows: (1) Are the symptoms due to peripheral neuropathy? (2) Is the neuropathy due to the underlying disease or the treatment? (3) Should treatment be modified or stopped because of the neuropathy? (4) What is the best supportive care in terms of pain management or physical therapy for each patient? Prevention of toxic neuropathies is most important. In patients with neuropathy, restorative approaches have not been well established. Symptomatic and other management are necessary to maintain and improve quality of life.

Anti-HuD-induced neuronal apoptosis underlying paraneoplastic gut dysmotility

BACKGROUND & AIMS

The role of autoimmunity underlying paraneoplastic gut dysmotility remains unsettled. Because anti-Hu antibodies may impair enteric neuronal function, we tested whether anti-HuD-positive sera from patients with paraneoplastic gut dysmotility or commercial anti-HuD antibodies activated the apoptotic cascade in a neuroblastoma cell line and cultured myenteric neurons.

METHODS

Anti-HuD antibodies from patients with severe paraneoplastic gut dysmotility were characterized by immunofluorescence and immunoblot. SH-Sy5Y neuroblasts and cultured myenteric neurons were exposed to sera containing anti-HuD antibodies or 2 commercial anti-HuD antibodies. Cells were processed for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) technique to evaluate apoptosis. Immunofluorescence was used to identify activated caspase-3 and apaf-1, along with microtubule-associated protein 2.

RESULTS

In SH-Sy5Y cells, the percentage of TUNEL-positive nuclei observed after exposure to anti-HuD-positive sera (32% +/- 7%) or anti-HuD antibodies (23% +/- 2%) was significantly greater than that of control sera or fetal calf serum (P < 0.001). The time-course analysis showed a significantly greater number of apoptotic neuroblastoma cells evoked by the 2 commercial anti-HuD antibodies at 24, 48, and 72 hours versus controls. The number of TUNEL-positive myenteric neurons exposed to anti-HuD antibodies (60% +/- 14%) was significantly greater than that of fetal calf serum (7% +/- 2%; P < 0.001). Apaf-1 and caspase-3 immunolabeling showed intense cytoplasmic staining in a significantly greater proportion of cells exposed to anti-HuD-positive sera or to commercial anti-HuD antibodies compared with controls.

CONCLUSIONS

Anti-HuD antibodies evoked neuronal apoptosis that may contribute to enteric nervous system impairment underlying paraneoplastic gut dysmotility. Apaf-1 activation suggests participation of a mitochondria-dependent apoptotic pathway.

Novel products of the HUD, HUC, NNP-1 and alpha-internexin genes identified by autologous antibody screening of a pediatric neuroblastoma library

Autologous serological screening of a cDNA expression library (SEREX) derived from childhood neuroblastoma led to the identification of 10 different antigens, including 6 novel gene products. The novel antigen 018INX was derived from a small open reading frame in a region of alpha-internexin mRNA that was previously described as 3' untranslated region. 018INX thus represents a novel type of tumor antigen. Five novel gene products were derived from NNP-1 (NNP3) and Hu genes (HuC-L, HuD3, HuDY, HuD1pro(c)). As indicated by sequence analysis, these antigens were generated by alternative splicing and/or alternative promoter usage or allelic polymorphism. mRNA expression analyses revealed different tissue restrictions of novel compared to known HuD and NNP-1 transcripts in normal and malignant tissues. The expressions patterns of distinct transcripts indicated potential clinical meanings as diagnostic and/or prognostic tissue markers. When kinetics of serum antibody titres against SEREX-defined antigens were compared to tumor load over time in our patient with neuroblastoma, we found 100-fold increases of anti-Hu and anti-018INX antibody titres preceding the clinical diagnosis of recurrent tumor growth after 2 years. When sera of pediatric patients with cancer (30) and healthy controls (30) were tested for humoral responses to SEREX-defined neuroblastoma antigens, we detected antibodies against all known antigens and NNP3 with low frequencies and titres in control sera, while anti-018INX and anti-Hu antibodies were found in cancer patients only. Our findings indicate that SEREX-defined tumor antigens might provide novel tools for understanding and treatment of this aggressive childhood malignancy.

Paraneoplastic syndromes associated with bronchogenic carcinoma

Paraneoplastic syndromes associated with lung cancer are diverse in their presentation, pathophysiology, and implications. They can be seen as a diagnostic and therapeutic challenge or as an opportunity to detect an otherwise asymptomatic malignancy. Unraveling the mechanisms that produce these syndromes will lead to insight into tumor biology that will be translated into novel approaches for early detection and therapy.

Phenotypic and neuropathologic heterogeneity of anti-Hu antibody-related paraneoplastic syndrome presenting with progressive dysautonomia: report of two cases

The anti-Hu antibody (HuAb) is directed against RNA-associated neuronal proteins and is known to cause paraneoplastic encephalomyelitis/sensory neuronopathy syndrome mostly when associated with small cell lung cancer (SCLC). Paraneoplastic encephalomyelitis/sensory neuronopathy syndrome with concurrent autonomic neuropathy has been reported to occur in paraneoplastic syndromes, although its occurrence concomitant with acute pandysautonomia is less frequent. The authors describe the clinical, neuropathologic, and serologic features of two cases with an anti-Hu-related paraneoplastic syndrome presenting with progressive autonomic neuropathy. Both patients showed features of dysautonomia, including postural dizziness, abdominal pain, and diarrhea, and symptoms of sensory neuropathy. Investigations disclosed severe sensory and autonomic neuropathy and positive HuAb titers. The disease of patient 1 had a very rapid progression, and the patient died of cardiac arrest within 2 months of the onset of symptoms. The autopsy revealed SCLC. In contrast, the disease of patient 2 had a less aggressive course. An extensive tumor search disclosed SCLC only 28 months after onset of symptoms, and the patient died 1 month later of cardiorespiratory arrest. Autopsies in both cases showed inflammation involving the intermediolateral columns and the dorsal root ganglia. These two cases illustrate the association of early dysautonomia with HuAb-related paraneoplastic syndrome and the variations of clinical, neuropathologic, and serologic findings in these types of cases.

Demonstration of anti-HuD specific oligoclonal bands in the cerebrospinal fluid from patients with paraneoplastic neurological syndromes. Qualitative evidence of anti-HuD specific IgG-synthesis in the central nervous system

The presence of HuD-specific oligoclonal IgG bands in the CSF was investigated in five patients with paraneoplastic neurological syndromes. All patients revealed intrathecal synthesis of HuD specific antibodies in the CSF, as estimated from elevated antibody indices (>1.5) in an IgG-ELISA using recombinant HuD-protein as antigen. Isoelectrofocussing combined with affinity blotting showed reactivity of IgG bands with recombinant HuD antigen in all CSF samples. These data support the idea that HuD specific antibodies in the CSF are produced mainly by B-cell clones in the central nervous system. These findings support the hypothesis of autoimmunity in the pathogenesis of anti-Hu associated paraneoplastic neurological syndromes.

Reversible paraneoplastic encephalomyelitis associated with a benign ovarian teratoma

BACKGROUND

Paraneoplastic encephalomyelitis (PEM) is a well characterized, and typically irreversible, paraneoplastic syndrome, usually associated with small cell lung cancer or other malignancy. We describe a case of a young woman with a benign ovarian teratoma who presented with a reversible PEM.

CASE REPORT

A 24-year-old woman presented with a three week history of memory impairment, unusual behavior, personality changes, auditory hallucinations, hypersomnolence and binocular biplopia. On admission she was disoriented and inattentive with impaired short term memory. Small doses of lorazepam (1 mg), given for episodic agitation, repeatedly induced multidirectional bilateral nystagmus and a skew deviation, but her neurological examination was otherwise normal. A left-sided pelvic mass was palpable. Brain MRI pre- and post-gadolinium was normal. There was a mild CSF pleocytosis and an EEG showed minimal bilateral background activity irregularities. There were no other laboratory abnormalities. Two weeks after admission, she clinically deteriorated developing central respiratory failure and a flaccid paraplegia. Repeat MRI showed an area of increased T2 weighted signal in the medulla and three similar areas in the spinal cord. Following removal of her tumor, treatment with high dose corticosteroids and intravenous immunoglobulin, she ultimately made a full recovery. Pathology revealed the tumor to be a benign ovarian cystic teratoma.

CONCLUSIONS

This is the first report of a reversible PEM seen in association with a benign tumor, in this case a mature ovarian teratoma. Presumably, an immune response directed against neural clements of the teratoma cross-reacted with normal brain, brainstem and spinal cord antigens to cause neurologic symptoms. Tumor removal was followed by neurologic recovery.

[Mechanisms of paraneoplastic neurologic syndromes]

INTRODUCTION

Paraneoplastic neurological syndromes (PNS) refer to a set of neurological disorders associated with neuronal degeneration in some patients with systemic cancers. These disorders are not related to the tumor mass or metastasis.

CURRENT KNOWLEDGE AND KEY POINTS

Evidence argues for an autoimmune reaction against tumor cells which expresses antigens normally present in neurons. A high percentage of patients with PNS harbors high titers of anti-neuronal autoantibodies in their serum and cerebrospinal fluid. In addition to their clinical interest in diagnosis and pathophysiology, these autoantibodies provide a unique opportunity to identify genes encoding previously undiscovered neuronal proteins which are also expressed by tumor cells. These "onconeural" antigens have been classified in four groups: neuromuscular junction proteins, nerve terminal/vesicle-associated proteins, neuronal RNA binding proteins, or neuronal signal transduction proteins.

FUTURE PROSPECTS AND PROJECTS

All of these proteins would play a major role in the neuronal maturation and homeostasis, and for some of them in cellular proliferation. Better understanding of the exact role of these proteins would in turn permit better understanding of the mechanisms of neuronal degeneration and tumor cell proliferation in PNS.

P/Q-type voltage-gated calcium channel antibodies in paraneoplastic disorders of the central nervous system

Whether P/Q-type voltage-gated calcium channel (VGCC) antibodies are present in the serum of patients with paraneoplastic syndromes other than the Lambert-Eaton myasthenic syndrome (LEMS) and tumors other than small-cell lung cancer (SCLC) is controversial. Using a commercially available radioimmunoprecipitation assay kit, we examined the sera of 93 patients with paraneoplastic syndromes of the central nervous system (CNS), including 27 patients with paraneoplastic cerebellar degeneration (PCD) associated with tumors other than SCLC and 66 SCLC patients with paraneoplastic encephalomyelitis and sensory neuronopathy (PEM/SN). All PCD sera from patients with tumors other than SCLC were negative for P/Q-type VGCC antibodies. Eight of 66 (12%) SCLC patients with PEM/SN had P/Q-type VGCC antibodies; 4 had LEMS and the other 4 had no symptoms of LEMS or they were overlooked and, therefore, not examined electrophysiologically. In patients with paraneoplastic syndromes of the CNS, the detection of P/Q-type VGCC antibodies supports the diagnosis of LEMS; in our series, only 6% of patients with SCLC and PEM/SN may have had a false positive antibody result, or undiagnosed LEMS.

Autoimmunity in paraneoplastic neurological disorders

Antibodies to neuronal antigens are found in a range of different neurological disorders, both central and peripheral, and often indicate the presence of particular underlying tumours. This conference and workshop was an opportunity to discuss the clinical associations of these antibodies, the relevance of new antibody specificities, and to establish protocols for their detection.

Paraneoplastic syndromes

Paraneoplastic syndromes (i.e. organ/tissue disorders associated with cancer) affecting the nervous system are thought to be the result of an autoimmune response triggered by specific cancer antigens. Several of these antigens have recently been identified and include the Hu, Yo and Ri proteins, with the Hu antigens being the best studied. Immunization of animals with HuD has been shown to retard the growth of HuD-positive neuroblastomas. In addition, the presence of anti-HuD antibody in humans with small-cell lung cancer predicts the slow growth of the tumor. The associated neurological disorders, however, limit the use of these and other antigens with similar characteristics in cancer vaccines.