Cell-mediated immune responses in paraneoplastic neurological syndromes

Recent advances in diagnosis of immune-mediated cerebellar ataxias: novel concepts and fundamental questions on autoimmune mechanisms

Immune-mediated cerebellar ataxias (IMCAs) represent a group of disorders in which the immune system targets mainly the cerebellum and related structures. We address fundamental questions on the diagnosis and immunological pathogenesis of IMCAs, as illuminated by recent advances in the field. Various types of IMCAs have been identified, including post-infectious cerebellitis, Miller Fisher syndrome, gluten ataxia, paraneoplastic cerebellar degeneration (PCD), opsoclonus and myoclonus syndrome, and anti-GAD ataxia. In some cases, identification of several well-characterized autoantibodies points to a specific etiology in IMCAs and leads to a firm diagnosis. In other cases, various autoantibodies have been reported, but their interpretation requires a careful consideration. Indeed, some autoantibodies have only been documented in a limited number of cases and the causal relationship is not established. In order to facilitate an early treatment and prevent irreversible lesions, new entities have been defined in recent years, such as primary autoimmune cerebellar ataxia (PACA) and latent autoimmune cerebellar ataxia (LACA). PACA is characterized by autoimmune features which do not align with traditional etiologies, while LACA corresponds to a prodromal stage. LACA does not imply the initiation of an immunotherapy but requires a close follow-up. Concurrently, accumulation of clinical data has led to intriguing hypotheses regarding the mechanisms of autoimmunity, such as a pathogenesis of autoimmunity against synapses (synaptopathies), and the vulnerability of the entire nervous system when the immunity targets ion channels and astrocytes. The development of PCD in patients treated with immune-checkpoint inhibitors suggests that molecular mimicry specifically determines the direction of autoimmunity, and that the strength of this response is modulated by co-signaling molecules that either enhance or dampen signals from the antigen-specific T cell receptor.

Progressive Encephalomyelopathy in an Older Man: A Case Report From the National Multiple Sclerosis Society Case Conference Proceedings

We present a case of subacute onset progressive encephalomyelopathy in a 77-year-old man with symmetric lateral column signal abnormalities on spinal MRI. We discuss the differential and presumptive final diagnosis along with a review of the postulated disease immunopathogenesis.

Autoantibodies related to ataxia and other central nervous system manifestations of gluten enteropathy

Gluten ataxia and other central nervous system disorders could be linked to gluten enteropathy and related autoantibodies. In this narrative review, we focus on the various neuro-logical manifestations in patients with gluten sensitivity/celiac disease, immunological and autoimmune mechanisms of ataxia in connection to gluten sensitivity and the autoantibodies that could be used as a biomarker for diagnosing and following. We focused on the anti-gliadin antibodies, antibodies to different isoforms of tissue transglutaminase (TG) (anti-TG2, 3, and 6 antibodies), anti-glycine receptor antibodies, anti-glutamine acid decarboxylase antibodies, anti-deamidated gliadin peptides antibodies, etc. Most studies found a higher prevalence of these antibodies in patients with gluten sensitivity and neurological dysfunction, presented as different neurological disorders. We also discuss the role of a gluten-free diet on the clinical improvement of patients and also on imaging of these disorders.

[Blood-brain barrier breakdown and autoimmune cerebellar ataxia]

Autoimmune cerebellar ataxia is a disease entity that affects the cerebellum and is induced by autoimmune mechanisms. The disease is classified into several etiologies, including gluten ataxia, anti-glutamate decarboxylase (GAD) ataxia, paraneoplastic cerebellar degeneration, primary autoimmune cerebellar ataxia and postinfectious cerebellar ataxia. The autoimmune response in the periphery cross-reacts with similar antigens in the cerebellum due to molecular mimicry. Breakdown of the blood‒brain barrier (BBB) could potentially explain the vulnerability of the cerebellum during the development of autoimmune cerebellar ataxia, as it gives rise to the entry of pathogenic autoantibodies or lymphocytes into the cerebellum. In this review, the maintenance of the BBB under normal conditions and the molecular basis of BBB disruption under pathological conditions are highlighted. Next, the pathomechanism of BBB breakdown in each subtype of autoimmune cerebellar ataxia is discussed. We recently identified glucose-regulated protein (GRP) 78 antibodies in paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome, and GRP78 antibodies induced by cross-reactivity with tumors can disrupt the BBB and penetrate anti-P/Q type voltage-gated calcium channel (VGCC) antibodies into the cerebellum, thus leading to cerebellar ataxia in this disease.

Alteration in PNMA1 expression is associated with poor prognosis and tumor immune infiltration in head and neck squamous cell carcinoma

BACKGROUND

A significant percentage of the world is distressed due to the widespread and aggressive head and neck squamous cell carcinoma (HNSCC). The prognosis for people with HNSCC remains grim, despite progress in treatment techniques. This underscores the pressing demand for the discovery of novel biomarkers to enable early detection and improve prognostic categorization.

OBJECTIVE

The present study aims to identify the expression of the PNMA1 gene in HNSCC with clinicopathological characteristics, prognosis, and association of immune cells infiltration.

METHODS

The TCGA-HNSCC dataset first evaluated PNMA1 expression and its relationship to clinical aspects of HNSCC. Following that, oral squamous cell carcinoma (OSCC), a primary HNSCC type, is used to validate PNMA1 mRNA expression, via quantitative reverse transcription PCR (RT-qPCR). The Kaplan-Meier plot was used to assess survival rates, and the Tumour Immune Estimation Resource (TIMER) database was used to examine the relationship between PNMA1 and immune cells infiltration.

RESULTS

The expression of PNMA1 significantly increased in HNSCC and OSCC tumors. Significant correlations have been found between the increased PNMA1 expression and clinicopathological characteristics of HNSCC, such as tumor stage, grade, metastasis, HPV status and patient survival. PNMA1 expression also correlated with immune cell infiltration and immune regulator genes.

CONCLUSION

In conclusion, the present study demonstrated that the PNMA1 expression significantly increased in HNSCC and was associated with HNSCC patient's prognosis. Hence, PNMA1 could serve as a novel prognostic biomarker and a promising therapeutic target for HNSCC.

Paraneoplastic neuropathies and peripheral nerve hyperexcitability disorders

Peripheral neuropathy is a common referral for patients to the neurologic clinics. Paraneoplastic neuropathies account for a small but high morbidity and mortality subgroup. Symptoms include weakness, sensory loss, sweating irregularity, blood pressure instability, severe constipation, and neuropathic pain. Neuropathy is the first presenting symptom of malignancy among many patients. The molecular and cellular oncogenic immune targets reside within cell bodies, axons, cytoplasms, or surface membranes of neural tissues. A more favorable immune treatment outcome occurs in those where the targets reside on the cell surface. Patients with antibodies binding cell surface antigens commonly have neural hyperexcitability with pain, cramps, fasciculations, and hyperhidrotic attacks (CASPR2, LGI1, and others). The antigenic targets are also commonly expressed in the central nervous system, with presenting symptoms being myelopathy, encephalopathy, and seizures with neuropathy, often masked. Pain and autonomic components typically relate to small nerve fiber involvement (nociceptive, adrenergic, enteric, and sudomotor), sometimes without nerve fiber loss but rather hyperexcitability. The specific antibodies discovered help direct cancer investigations. Among the primary axonal paraneoplastic neuropathies, pathognomonic clinical features do not exist, and testing for multiple antibodies simultaneously provides the best sensitivity in testing (AGNA1-SOX1; amphiphysin; ANNA-1-HU; ANNA-3-DACH1; CASPR2; CRMP5; LGI1; PCA2-MAP1B, and others). Performing confirmatory antibody testing using adjunct methods improves specificity. Antibody-mediated demyelinating paraneoplastic neuropathies are limited to MAG-IgM (IgM-MGUS, Waldenström's, and myeloma), with the others associated with cytokine elevations (VEGF, IL6) caused by osteosclerotic myeloma, plasmacytoma (POEMS), and rarely angiofollicular lymphoma (Castleman's). Paraneoplastic disorders have clinical overlap with other idiopathic antibody disorders, including IgG4 demyelinating nodopathies (NF155 and Contactin-1). This review summarizes the paraneoplastic neuropathies, including those with peripheral nerve hyperexcitability.

Immunoreactivity to astrocytes in different forms of dementia: High prevalence of autoantibodies to GFAP

Objective

To study the prevalence of autoantibodies to glial and neuronal antigens with a focus on glial acidic fibrillary protein (GFAP) in patients with dementia.

Methods

Sera of 127 patients with different forms of dementia and sera of 82 age-matched patients with various neurological diseases except for dementia, as well as sera from 15 age-matched healthy controls were analyzed for anti-glial or anti-neuronal IgG using 1) primary murine embryonic hippocampus cell cultures, 2) murine brain sections, 3) immunoblotting on mouse brain homogenates and 4) astrocyte cultures. Sera reacting with astrocytes in hippocampus cell cultures were further analyzed using HEK293 cells transfected with human GFAP.

Results

IgG in serum from 45 of 127 (35.5%) patients with dementia but only 8 of 97 (8.2%, p ≤ 0.001) controls bound to either glial or neuronal structures in cultured murine hippocampus cells. In these cultures antibodies to astrocytes were detected in 35 of 127 (27.5%) of the dementia patients, whereas in controls antibodies to astrocytes were detected in 4 sera only (4.1%, p ≤ 0.001). Among the sera exhibiting reactivity to astrocytes, 14 of 35 (40%) showed immunoreaction to HEK293 cells transfected with GFAP in dementia patients, representing 11% of all sera. Within the 4 immunoreactive control sera reacting with astrocytes one reacted with GFAP (1.0% of total immunoreactivity, p = 0.003).

Conclusions

Autoantibodies to glial epitopes in general and to GFAP in particular are more frequent in patients with dementia than in age-matched controls without dementia, thus indicating the need for further investigations regarding the potential pathophysiological relevance of these antibodies.

Anti-Tr/DNER Antibody-Associated Cerebellar Ataxia: a Systematic Review

Rapidly progressive cerebellar ataxia is a classical paraneoplastic neurological syndrome associated with different autoantibodies and typical demographic characteristics, extracerebellar signs, tumor association, and prognosis. Anti-Tr/anti-Delta/Notch-like epidermal growth factor-related receptor (DNER) antibody is one of the associated antibodies. Given the rarity of this condition, our current knowledge is based on case reports and small case series. In order to improve our understanding of these conditions, we conducted a systematic review of the literature. Our study followed the PRISMA reporting guidelines. Studies of patients with the presence of anti-Tr/DNER antibodies in serum or cerebrospinal fluid (CSF) were included. We extract data information related to study characteristics, demographics, clinical symptoms, tumor association, neuroimaging, and cerebrospinal fluid analysis. Out of 131 records, we analyzed 17 papers, including a total of 85 patients with anti-Tr/DNER antibody-associated cerebellar ataxia. We confirmed that this disease occurred mostly in middle-aged males. Isolated cerebellar ataxia was the most common presentation. Extracerebellar features were rare (8%). Ninety-one percent of the patients presented an associated tumor, being Hodgkin lymphoma the most common. Abnormal neuroimaging patterns included cerebellar atrophy (19%) and cerebellar hypersignal (6%). Cerebrospinal fluid was inflammatory in 64% of the patients. Oncological response was complete in 88%, but neurological prognosis was poor with only 41% of the patients presenting significant neurological improvement at the last follow up. Anti-Tr/DNER antibodies should be tested in rapid progressive cerebellar ataxia. Oncological response is excellent; however, many patients do not improve from their cerebellar ataxia.

BILATERAL SERPIGINOUS-LIKE CHORIORETINITIS ASSOCIATED WITH CILIOCHOROIDAL MELANOMA: A Clinicopathologic Correlation

PURPOSE

To report the clinicopathologic correlation of a case of bilateral serpiginous-like chorioretinitis (SLC) associated with unilateral ciliochoroidal melanoma.

METHODS

A 71-year-old white woman was diagnosed with progressive SLC in both eyes associated with ciliochoroidal melanoma in the right eye. Clinical findings and imaging before and after enucleation in the right eye were correlated to histologic and immunohistochemistry sections.

RESULTS

Examination and imaging identified a peripheral bilobed amelanotic lesion with low reflectivity on B-scan ultrasound with an associated exudative detachment in the right eye. Additionally, multiple areas of new SLC lesions in the macula and peripapillary region in the right eye and along the inferior arcade in the left eye were observed. Oncologic evaluation confirmed a Class 2, ciliochoroidal melanoma, and the eye was enucleated. Autoimmune and infectious laboratory evaluations for the etiology of the SLC lesions were negative. Histopathology of the enucleated eye confirmed the diagnosis of uveal melanoma with lymphocytic inflammation at the edges of the tumor itself and in the areas of discrete SLC lesions. Immunohistochemistry identified similar predominantly CD3 and CD8 T cells and fewer CD20 B cells in both regions.

CONCLUSION

Serpiginous-like chorioretinitis may present as a paraneoplastic, predominantly T-lymphocyte inflammation associated with intraocular tumor such as uveal melanoma.

Sarcoidosis or cancer? That is the question

Sarcoidosis is a granulomatous inflammatory disease of unknown etiology. Sarcoid like granuloma may develop concurrently or following cancer. Detection of granuloma in mediastinal lymph nodes biopsy in patient with pulmonary nodules may be a concern for undiagnosed lung cancer. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a diagnostic modality of choice for the lung lesions.

We discussed A 71-year-old man with history of chronic obstructive lung disease (COPD), who presented with a lung nodule and mediastinal lymphadenopathies. The nodule was 9.9 mm when detected and his endobronchial ultrasound-guided transbronchial fine needle aspiration (EBUS-TBNA) of lymph nodes in station 7 & 4R showed normal lymph node structure. Two years later, his surveillance chest CT scan indicated an increase in the size of the nodule to 15 mm, and PET/CT showed Fluorodeoxyglucose (FDG) avid nodule & mediastinal Lymph nodes. He complained of Shortness of breath after 2–3 climbs of stairs, without any history of cough or fever. He quit cigarette smoking recently and smoked 50 pack years before. He underwent another set of EBUS and was referred for sarcoidosis treatment due to finding non-necrotizing granuloma in 4L and 11L lymph nodes. The patient also underwent another biopsy of the nodule concerning the possibility of cancer sarcoid syndrome. A poorly differentiated lung adenocarcinoma positive for GATA3, positive for P63 and CK7, TTF-1 was reported.

Concurrent lung cancer and granulomatous reaction in mediastinal lymph nodes are being reported more often. Recent studies have shown a better survival of patients with diagnosis of cancer and granulomatous findings of sarcoidosis. Performing lung biopsy from any nodular lesion in a patient with sarcoidosis is essential for the differential diagnosis and early therapeutic measures.

Antibodies Against the NH2-Terminus of the GluA Subunits Affect the AMPA-Evoked Releasing Activity: The Role of Complement

Antibodies recognizing the amino-terminal domain of receptor subunit proteins modify the receptor efficiency to controlling transmitter release in isolated nerve endings (e.g., synaptosomes) indirectly confirming their presence in these particles but also allowing to speculate on their subunit composition. Western blot analysis and confocal microscopy unveiled the presence of the GluA1, GluA2, GluA3, and GluA4 receptor subunits in cortical synaptosomes. Functional studies confirmed the presence of presynaptic release-regulating AMPA autoreceptors in these terminals, whose activation releases [3H]D-aspartate ([3H]D-Asp, here used as a marker of glutamate) in a NBQX-dependent manner. The AMPA autoreceptors traffic in a constitutive manner, since entrapping synaptosomes with the pep2-SVKI peptide (which interferes with the GluA2-GRIP1/PICK1 interaction) amplified the AMPA-evoked releasing activity, while the inactive pep2-SVKE peptide was devoid of activity. Incubation of synaptosomes with antibodies recognizing the NH2 terminus of the GluA2 and the GluA3 subunits increased, although to a different extent, the GluA2 and 3 densities in synaptosomal membranes, also amplifying the AMPA-evoked glutamate release in a NBQX-dependent fashion. We then analyzed the releasing activity of complement (1:300) from both treated and untreated synaptosomes and found that the complement-induced overflow occurred in a DL-t-BOA-sensitive, NBQX-insensitive fashion. We hypothesized that anti-GluA/GluA complexes in neuronal membranes could trigger the classic pathway of activation of the complement, modifying its releasing activity. Accordingly, the complement-evoked release of [3H]D-Asp from antiGluA2 and anti-GluA3 antibody treated synaptosomes was significantly increased when compared to untreated terminals and facilitation was prevented by omitting the C1q component of the immunocomplex. Antibodies recognizing the NH2 terminus of the GluA1 or the GluA4 subunits failed to affect both the AMPA and the complement-evoked tritium overflow. Our results suggest the presence of GluA2/GluA3-containing release-regulating AMPA autoreceptors in cortical synaptosomes. Incubation of synaptosomes with commercial anti-GluA2 or anti-GluA3 antibodies amplifies the AMPA-evoked exocytosis of glutamate through a complement-independent pathway, involving an excessive insertion of AMPA autoreceptors in plasma membranes but also affects the complement-dependent releasing activity, by promoting the classic pathway of activation of the immunocomplex. Both events could be relevant to the development of autoimmune diseases typified by an overproduction of anti-GluA subunits.

Immune-Mediated Cerebellar Ataxias: Clinical Diagnosis and Treatment Based on Immunological and Physiological Mechanisms

Since the first description of immune-mediated cerebellar ataxias (IMCAs) by Charcot in 1868, several milestones have been reached in our understanding of this group of neurological disorders. IMCAs have diverse etiologies, such as gluten ataxia, postinfectious cerebellitis, paraneoplastic cerebellar degeneration, opsoclonus myoclonus syndrome, anti-GAD ataxia, and primary autoimmune cerebellar ataxia. The cerebellum, a vulnerable autoimmune target of the nervous system, has remarkable capacities (collectively known as the cerebellar reserve, closely linked to plasticity) to compensate and restore function following various pathological insults. Therefore, good prognosis is expected when immune-mediated therapeutic interventions are delivered during early stages when the cerebellar reserve can be preserved. However, some types of IMCAs show poor responses to immunotherapies, even if such therapies are introduced at an early stage. Thus, further research is needed to enhance our understanding of the autoimmune mechanisms underlying IMCAs, as such research could potentially lead to the development of more effective immunotherapies. We underscore the need to pursue the identification of robust biomarkers.

Granzyme B in peripheral blood mononuclear cells as a measure of cell-mediated immune response in paraneoplastic neurological syndromes and malignancy

Background

Paraneoplastic neurological syndromes (PNS) may coexist with ovarian or lung cancers. Some tumors coexisting with PNS are smaller and have a better prognosis than tumors without PNS. PNS may constitute an opportunity to observe a natural immune antitumor response. We aimed to investigate a cytotoxic immune response by measuring granzyme B (GrB) in peripheral blood mononuclear cells (PBMC) in patients affected with ovarian or lung malignancy, with and without accompanying PNS.

Methods

We enrolled patients with: nonmalignant lesions (n = 21), ovarian cancer (n = 19), lung cancer (n = 57), and PNS (n = 30). PBMC were isolated by density gradient centrifugation with Ficoll–Paque. We evaluated the expression of GrB in PBMC lysates by ELISA and normalized to protein content as measured by the Lowry method.

Results

GrB levels in PBMC in the group with malignant tumors—median 1650 pg/mg protein (interquartile range 663–3260 pg/mg) and in patients with PNS—median 1890 pg/mg protein (range 1290–2640 pg/mg) was lower than in control group with nonmalignant lesions—median 5240 pg/mg protein (range 2160–7440 pg/mg), p = 0.0003 and p = 0.0038, respectively. The differences in GrB levels in PBMC between these groups were independent of epidemiological factors—age, sex, body mass index (BMI), and the number of immune cells, as confirmed by multiple regression analysis. Within the group of patients with malignancy and PNS, GrB levels in PBMC were elevated if onconeural antibodies were detected (2610; 2390–3700 pg/mg protein) as compared to patients without antibodies (1680; 970–1880 pg/mg protein, p = 0.035). GrB in PBMC was higher if the malignancy was diagnosed at the low (3060; 2120–5220 pg/mg protein) as compared to the high stage (1330; 348–2140, p = 0.00048). In patients with lung cancer, the expression of GrB in PBMC was lower (1430; 635–2660 pg/mg protein) than in the group with ovarian cancer (2580; 1730–3730, p = 0.02).

Conclusion

The cytotoxic response measured in peripheral blood by GrB in PBMC is impaired both in the course of malignancy and PNS. Levels of GrB in PBMC were higher if onconeural antibodies were detected. Tracking reactive immune responses, such as GrB in PBMC may have diagnostic and monitoring value in malignancy and PNS.

Electronic supplementary material

The online version of this article (10.1007/s00262-020-02750-1) contains supplementary material, which is available to authorized users.

Gray E. Tumour PD-L1 Expression in Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Antibodies against programmed death-1 (PD-1), and its ligand, (PD-L1) have been approved recently for the treatment of small-cell lung cancer (SCLC). Although there are previous reports that addressed PD-L1 detection on tumour cells in SCLC, there is no comprehensive meta-analysis on the prevalence of PD-L1 expression in SCLC. We performed a systematic search of the PubMed, Cochrane Library and EMBASE databases to assess reports on the prevalence of PD-L1 expression and the association between PD-L1 expression and overall survival (OS). This meta-analysis included 27 studies enrolling a total of 2792 patients. The pooled estimate of PD-L1 expression was 26.0% (95% CI 17.0–37.0), (22.0% after removing outlying studies). The effect size was significantly heterogeneous (I² = 97.4, 95% CI: 95.5–98.5, p < 0.0001).Positive PD-L1 expression was a favourable prognostic factor for SCLC but not statistically significant (HR = 0.86 (95% CI (0.49–1.50), p = 0.5880; I² = 88.7%, p < 0.0001). Begg’s funnel plots and Egger’s tests indicated no publication bias across included studies (p > 0.05). Overall, there is heterogeneity in the prevalence of PD-L1 expression in SCLC tumour cells across studies. This is significantly moderated by factors such as immunohistochemistry (IHC) evaluation cut-off values, and assessment of PD-L1 staining patterns as membranous and/or cytoplasmic. There is the need for large size, prospective and multicentre studies with well-defined protocols and endpoints to advance the clinical value of PD-L1 expression in SCLC.

Innate Immunity in the Central Nervous System: A Missing Piece of the Autoimmune Encephalitis Puzzle?

The autoimmune encephalitides are a group of autoimmune conditions targeting the central nervous system and causing severe clinical symptoms including drug-resistant seizures, cognitive dysfunction and psychiatric disturbance. Although these disorders appear to be antibody mediated, the role of innate immune responses needs further clarification. Infiltrating monocytes and microglial proliferation at the site of pathology could contribute to the pathogenesis of the disease with resultant blood brain barrier dysfunction, and subsequent activation of adaptive immune response. Both innate and adaptive immune cells can produce pro-inflammatory molecules which can perpetuate ongoing neuroinflammation and drive ongoing seizure activity. Ultimately neurodegenerative changes can ensue with resultant long-term neurological sequelae that can impact on ongoing patient morbidity and quality of life, providing a potential target for future translational research.

Isolated adrenocorticotropic hormone deficiency as a form of paraneoplastic syndrome

PURPOSE

In isolated adrenocorticoropic hormone (ACTH) deficiency (IAD), autoimmunity against corticotrophs has been suggested; however, the pathogenesis remains largely unknown. Large cell neuroendocrine carcinoma (LCNEC) of the lung is a pulmonary tumor of high-grade malignant neuroendocrine tumor and it reportedly caused paraneoplastic syndrome by autoimmunity in several cases.

METHODS

A 42-year-old woman with isolated adrenocorticotropic (ACTH) hormone deficiency (IAD) was diagnosed with large cell neuroendocrine carcinoma (LCNEC) 3 years after being diagnosed with IAD. We hypothesized that the LCNEC played a causal role in the development of IAD as a paraneoplastic syndrome and analyzed the autoimmunity. We also analyzed another case of ectopic ACTH syndrome to prove this hypothesis.

RESULTS

The LCNEC tissue revealed an ectopic ACTH expression and lymphocyte infiltration. Interestingly, autoantibody against the proopiomelanocortin (POMC) protein was detected in the peripheral blood. Although, patient's serum did not show any effects on cell viability, proliferation, nor pomc expression in a corticotroph cell line, AtT20 cells, patient's lymphocytes in the peripheral blood specifically reacted toward POMC protein, indicating a presence of cytotoxic T lymphocytes (CTLs). In addition, the analysis of another case of ectopic ACTH syndrome showed lymphocyte infiltration not only in the metastatic liver tumors but also in the pituitary. Moreover, most CD8-positive cells resided adjacent to corticotrophs.

CONCLUSIONS

These data indicate that the ectopic ACTH expression in the tumor evoked the autoimmunity to corticotrophs and caused IAD as a form of paraneoplastic syndrome.

Paraneoplastic Encephalopathy in a Patient With Metastatic Lung Cancer: A Case Study

CASE STUDY RS, a 36-year-old female, presented to the emergency department (ED) of a large academic medical center upon the advice of her primary care provider because of 3 weeks of progressive mental status changes, weakness, and decreased oral intake. According to her husband, RS was diagnosed with stage IIIA large cell lung cancer 8 months earlier and was treated with concurrent chemotherapy (carboplatin, pemetrexed, and bevacizumab) and radiation therapy that was completed 4 months prior to admission. No other specific information about her treatment or outside health records was available. According to her husband, RS had been in her usual state of health until approximately 3 weeks prior, when she began having significant mental status changes. She first exhibited some difficulty finding words and later was noted to be putting food in a coffee maker. This spontaneously resolved after approximately 1 week; however, she rapidly developed slurred speech and began to make nonsensical statements. These manifestations also slowly improved but were followed by worsening speech deficit, difficulty walking, and impaired balance. During one of these episodes, she had an occurrence of incontinence. Her husband also noted an incident where her "eyes were beating back and forth and the left side of her face was twitching." RS also had periods (according to her husband) where she "did not seem to be interacting with her environment." These progressively worsened during the last week, and she completely stopped walking and talking 2 days prior to coming to the ED. According to her husband, RS had rheumatoid arthritis and no surgical history. Her family history was unknown except that RS's mother had "seizures." RS had reportedly not used tobacco, alcohol, or drugs, and she was sexually active with her husband. Home medications included transdermal fentanyl 12 μg/hr patch changed every 72 hours; oxycodone-acetaminophen tablets 5-325 mg, two every 4 hours as needed for pain; prednisone 10 mg, one tablet daily; and megestrol 40 mg/mL suspension, 20 mL once daily for appetite stimulation. RS was admitted to an inpatient medical oncology service and evaluated by the oncology advanced practitioner (AP) on her second inpatient day. Upon exam, RS was nonverbal except for moaning in response to painful stimuli and to her sister's voice. Her vital signs were normal. She appeared ill but well-nourished, and she was mildly diaphoretic. Neurologic examination revealed that her pupils were slightly sluggish but equal, round, and reactive to light. Extraocular muscle movements were intact, but she did not move her eyes in response to commands. She tracked the AP and family members around the room with her eyes. Cranial nerve examination was intact with the exception of cranial nerves IX, X, and XI, which were difficult to examine given her inability to cooperate and open her mouth. Motor examination revealed increased tone throughout and intermittent, inconsistent resistance to passive movement. She was seen to move all four extremities spontaneously although not in response to commands. Deep tendon reflexes were intact and equal in all extremities. Examination of other body systems was as follows: there was dry, peeling skin on her lips, but her mucous membranes were moist and free of erythema or lesions. Her lungs were clear to auscultation bilaterally. Her heart rate and rhythm were regular, there were no murmurs, rubs, or gallops, and distal pulses were intact. Her abdomen was nondistended with normally active bowel sounds in all four quadrants. Her abdomen was soft, nontender to palpation, and without palpable masses. There was no peripheral discoloration, temperature changes, or edema, and examination of her skin was benign. Workup On admission to the emergency department, serum laboratory studies were unrevealing for any potential causes of encephalopathy. Kidney and liver function were normal, making diagnoses of uremic and hepatic encephalopathies less likely. Cultures of the urine and blood were negative. Samples of cerebrospinal fluid (CSF) were obtained via lumbar puncture and were unrevealing for any abnormalities. Computed tomography (CT) of the head without contrast was negative for any acute intracranial process. Ultrasound of the right upper quadrant revealed a single, nonspecific, hypoechoic hepatic lesion. Computed tomography scans of the chest, abdomen, and pelvis demonstrated the primary malignancy in the upper lobe of the left lung, as well as possible metastatic disease within the left lung, right lung, and liver, and widespread osseous metastatic disease. Magnetic resonance imaging (MRI) of the brain performed 1 day after admission demonstrated numerous scattered punctate foci of enhancement throughout the supratentorial and infratentorial brain parenchyma, measuring at most 3 to 4 millimeters in diameter. There was no significant mass effect or midline shift. A paraneoplastic panel was sent to an outside laboratory and returned positive for antivoltage-gated potassium channel (VGKC) autoantibodies. Differential Diagnosis Clinically, RS was exhibiting signs of encephalopathy, a broad term that indicates general brain dysfunction, the hallmark of which is altered mental status. Diagnosing encephalopathy is challenging, as many differential diagnoses must be considered. The clinician must consider metabolic derangements, toxic and infectious etiologies, psychiatric disorders, and less commonly, prion disorders and progressive dementia. Cultures of RS's blood and urine as well as other specialized endocrine tests were negative, decreasing the likelihood of a metabolic or infectious cause for her presentation. The abnormalities on her brain MRI were reviewed by a neuro-oncology team, who felt that the faint, nondescript nature of the visualized lesions was not suspicious for metastatic disease. Sequelae of seizures was also considered by neuro-oncology but dismissed given a grossly normal prolonged electroencephalogram. Some encephalopathies are caused by autoimmune or inflammatory mechanisms, which are confirmed by the presence of autoantibody markers and/or clear response to immunomodulatory treatment (Vernino, Geschwind, & Boeve, 2007). These types of encephalopathies have been seen in patients with cancer and have thus been termed paraneoplastic. The presence of anti-VGKC antibodies on RS's paraneoplastic panel directed the inpatient medical oncology team toward a paraneoplastic neurologic disorder (PND) as the most likely diagnosis.

PNMA family: Protein interaction network and cell signalling pathways implicated in cancer and apoptosis

Paraneoplastic Ma Family (PNMA) comprises a growing number of family members which share relatively conserved protein sequences encoded by the human genome and is localized to several human chromosomes, including the X-chromosome. Based on sequence analysis, PNMA family members share sequence homology to the Gag protein of LTR retrotransposon, and several family members with aberrant protein expressions have been reported to be closely associated with the human Paraneoplastic Disorder (PND). In addition, gene mutations of specific members of PNMA family are known to be associated with human mental retardation or 3-M syndrome consisting of restrictive post-natal growth or dwarfism, and development of skeletal abnormalities. Other than sequence homology, the physiological function of many members in this family remains unclear. However, several members of this family have been characterized, including cell signalling events mediated by these proteins that are associated with apoptosis, and cancer in different cell types. Furthermore, while certain PNMA family members show restricted gene expression in the human brain and testis, other PNMA family members exhibit broader gene expression or preferential and selective protein interaction profiles, suggesting functional divergence within the family. Functional analysis of some members of this family have identified protein domains that are required for subcellular localization, protein-protein interactions, and cell signalling events which are the focus of this review paper.

Detection of brain-directed autoantibodies in the serum of non-small cell lung cancer patients

Antibodies against brain proteins were identified in the plasma of cancer patients and are defined to cause paraneoplastic neurological syndromes. The profiles of brain-directed antibodies in non-small cell lung cancer (NSCLC) are largely unknown. Here, for the first time, we compared autoantibodies against brain proteins in NSCLC (n = 18) against those present in age-matched non-cancer control subjects (n = 18) with a similar life-style, habit, and medical history. Self-recognizing immunoglobulin (IgG) are primarily directed against cells in the cortex (P = 0.008), hippocampus (P = 0.003–0.05), and cerebellum (P = 0.02). More specifically, IgG targets were prominent in the pyramidal, Purkinje, and granule cell layers. Furthermore, autoimmune IgG signals were localized to neurons (81%), astrocytes (48%), and endothelial (29%) cells. While cancer sera yielded overall higher intensity signals, autoantigens of 100, 65, 45, 37, and 30 kDa molecular weights were the most represented. Additionally, a group of 100 kDa proteins seem more prevalent in female adenocarcinoma patients (4/5, 80%). In conclusion, our results revealed autoantigen specificity in NSCLC, which implicitly depends on patient’s demographics and disease history. Patients at risk for lung cancer but with no active disease revealed that the immune profile in NSCLC is disease-dependent.

Added diagnostic utility of PET in a patient with subacute encephalopathy and small-cell lung cancer

Diagnosis of paraneoplastic neurologic disorder (PND) synthesizes the clinical picture (including the temporal relationship to the cancer diagnosis), detection of onconeural antibodies and exclusion of alternative causes. The mainstay of brain imaging of PNDs is MRI. There is also an increasingly recognized role of PET using radiotracer ¹⁸F-Fluorodeoxyglucose (FDG) in the evaluation of the brain. We describe a 67-year-old female with a 50-year smoking history and small-cell lung cancer developing subacute encephalopathy with MRI and PET abnormalities identifying paraneoplastic encephalitis. PET may complement conventional tools in diagnosing a subset of patients with PND.

Imbalance in circulating T lymphocyte subsets contributes to Hu antibody-associated paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes (PNS) are associated with small cell lung cancer (SCLC) and Hu antibodies, which are considered to have an immune-mediated etiology. As a pathogenic role for Hu antibodies (Hu-Ab) in PNS could not be demonstrated, the cellular immune response against the Hu proteins has been further investigated. To delve deeper into the hypothesized cell-mediated immune pathogenesis of these syndromes, imbalances within circulating T lymphocyte subsets were investigated to determine their significance in Hu antibody-associated PNS. The circulating T lymphocyte subsets were analyzed in untreated patients with SCLC, PNS and Hu-Ab (n=10), SCLC without PNS (n=10) and healthy controls (n=12) using flow cytometry. Patients with PNS and SCLC, had a variety of changes within their circulating T lymphocyte subsets, which included; lymphopenia of the CD3(+)and CD4(+) T cells, increased proportions of total activated T cells and activated CD4(+) T cells, and reduced numbers of CD4(+) and CD25(+) regulatory T cells (Treg). These results suggest that the excessive activation of T cells and dysfunction of Treg contribute to Hu antibody-associated PNS.

Paraneoplastic neurological syndromes associated with ovarian tumors

Introduction

Paraneoplastic neurological syndromes (PNS) are neurologic deficits triggered by an underlying remote tumor. PNS can antedate clinical manifestation of ovarian malignancy and enable its diagnosis at an early stage. Interestingly, neoplasms associated with PNS are less advanced and metastasize less commonly than those without PNS. This suggests that PNS may be associated with a naturally occurring antitumor response.

Methods

We review the literature on the diagnosis, pathogenesis and management of PNS associated with ovarian tumors: paraneoplastic cerebellar degeneration (PCD) and anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. An approach to the diagnostic workup of underlying tumors is discussed.

Results

PCD can precede the manifestation of ovarian carcinoma. Anti-NMDAR encephalitis in young women appears often as a result of ovarian teratoma. Since ovarian tumors and nervous tissue share common antigens (e.g., cdr2, NMDAR), autoimmune etiology is a probable mechanism of these neurologic disorders. The concept of cross-presentation, however, seems insufficient to explain entirely the emergence of PNS. Early resection of ovarian tumors is a significant part of PNS management and improves the outcome.

Conclusions

The diagnosis of PNS potentially associated with ovarian tumor indicates a need for a thorough diagnostic procedure in search of the neoplasm. In some patients, explorative laparoscopy/laparotomy can be considered.