Paraneoplastic antibodies against HuD detected by a sensitive radiobinding assay

Study on the pro-inflammatory mechanism of the HuD antibody in promoting M1 polarization and paraneoplastic neurological syndrome occurrence

Paraneoplastic neurological syndrome (PNS) is a nonmetastatic complication of malignant tumors that may lead to immune-mediated neuronal dysfunction or death. The occurrence of PNS results from the binding of anti-neuronal antibodies to neuronal cell surface antigens or intracellular antigens, which hinders the function of target proteins and promotes cell death. The aim of this study is to research the effect and immune mechanism of the neuronal ELAV-like protein (HuD antibody) on PNS-related syndrome. Neuronal cells were co-cultured with monocyte macrophages with or without HuD antibody. Next, we detected the apoptosis of neuronal cells by flow cytometry. Meantime, macrophage M1/M2 polarization factors and the secretion of inflammatory factors in the co-culture system were also detected by quantitative polymerase chain reaction (qPCR), Western blots and ELISA technologies. The results showed that after adding the HuD antibody in the co-culture system, the apoptosis level of the neuroma cells were significantly increased, and the apoptosis level were not significant changed when co-culture with monocytes without HuD antibody. In addition, the level of factors of M1 macrophages TNF-α, IL-12, TGF-β and IFN-γ increased, while the level of factors of M2 macrophages IL-10, IL-4, and Arg-1 decreased. The outcomes demonstrated that absorption of the HuD antibody by cerebellar neuronal cells could promote the proliferation of M1 macrophages and stimulates macrophages to secrete inflammatory factors, further damage the neuronal cells, eventually resulting in the occurrence of PNS. This finding provided a theoretical basis for the subsequent treatment and prevention of PNS.

Expression of the onconeural protein CDR1 in cerebellum and ovarian cancer

Cerebellar degeneration related protein 1 (CDR1) is expressed in the cerebellum, and CDR1 antibodies have been associated with paraneoplastic cerebellar degeneration (PCD). In this study, we examined CDR1 expression in cerebellum and in ovarian and breast tumors, as well as the intracellular localization of CDR1 in cancer cells in culture. CDR1 was strongly expressed in the cytosol and dendrites of Purkinje cells and in interneurons of the molecular layer in cerebellum. CDR1 was also present in ovarian and breast tumors, as well as in ovarian and breast cancer cell lines, but was not present in normal breast or ovarian tissue. In cells overexpressing CDR1, CDR1 localized close to the plasma membrane in a polarized pattern at one edge. CDR1 was strongly expressed on the outer surface, apparently in filopodias or lamellipodias, in cells endogenously expressing CDR1. Overexpression of CDR1 showed a 37 and a 45 kDa band in western blot. The 37-kDa isoform was present in 16 ovarian cancer lysates, while the 45-kDa isoform was only found in three ovarian cancer patients. The presence of CDR1 in ovarian cancer was not associated with PCD. CDR1 antibodies were only found in serum from one patient with PCD and ovarian tumor with metastases. Therefore, CDR1 is probably not a marker for PCD. However, CDR1 may be associated with cell migration and differentiation.

Cerebellar degeneration-related proteins 2 and 2-like are present in ovarian cancer in patients with and without Yo antibodies

BACKGROUND

Cerebellar degeneration-related protein 2 (CDR2) has been presumed to be the main antigen for the onconeural antibody Yo, which is strongly associated with ovarian cancer and paraneoplastic cerebellar degeneration (PCD). Recent data show that Yo antibodies also target the CDR2-like protein (CDR2L). We, therefore, examined the expression of CDR2 and CDR2L in ovarian cancer tissue from patients with and without Yo antibodies and from various other cancerous and normal human tissues.

METHODS

Ovarian cancer tissue and serum samples from 16 patients were included in the study (four with anti-Yo and PCD, two with anti-Yo without PCD, five with only CDR2L antibodies, and five without onconeural antibodies). Clinical data were available for all patients. The human tissues were examined by western blot and immunohistochemistry using rabbit CDR2 and CDR2L antibodies.

RESULTS

Ovarian cancers from all 16 patients expressed CDR2 and CDR2L proteins. Both proteins were also present in normal and cancer tissue from mammary tissue, kidney, ovary, prostate, and testis.

CONCLUSION

CDR2L is present in ovarian cancers from patients with and without Yo antibodies as was shown previously for CDR2. In addition, both CDR2 and CDR2L proteins are more widely expressed than previously thought, both in normal and cancerous tissues.

Antibody to CCDC104 is associated with a paraneoplastic antibody to CDR2 (anti-Yo)

Patients with cancer may develop paraneoplastic neurological syndromes (PNS) in which onconeural antibodies are important diagnostic findings. As the functional role of onconeural antibodies is largely unknown, insight gained by identifying associated antibodies may help to clarify the pathogenesis of the PNS. In this study, we identified patients with Yo antibodies who also had antibodies to an uncharacterized protein called coiled-coil domain-containing protein 104 (CCDC104). We found a significant association between CCDC104 and Yo antibodies (4 of 38, 10.5%), but not other onconeural antibodies (0 of 158) (P = 0.007, Fisher's exact test). The prevalence of CCDC104 antibodies was approximately similar in patients with cancer (8 of 756, 1.1%) and in healthy blood donors (2 of 300, 0.7%). CCDC104 antibodies were not associated with PNS, as this was found in only two of the ten CCDC104-positive patients. The CCDC104 protein, whose function is unknown, is expressed in various human tissues, including the brain, and is localized mainly to the nucleus, but is also found in the cytoplasm. The association between Yo and CCDC104 antibodies may indicate functional similarities.

Autoantibody profiling for cancer detection

Despite substantial progress in the understanding of the pathogenesis of cancer, the development and implementation of strategies for early cancer detection have lagged behind. Harnessing the immune response to tumor antigens is particularly useful for early detection because the immune response occurs early during tumor development and affords signal amplification with the end product, namely reactive immunoglobulins, being released into the circulation allowing easy access through the blood. This article presents recent developments in autoantibody profiling with a focus on proteomic approaches and applications to lung cancer.

CRMP5 antibodies in patients with small-cell lung cancer or thymoma

The collapsin response mediator protein 5 (CRMP5) antibody is usually associated with paraneoplastic neurological syndrome (PNS) and small-cell lung cancer (SCLC) or thymoma. The objective of this study was to assess the frequency of CRMP5 antibodies in patients with such tumours and to see if the presence of antibodies was associated with prognosis in these cancers. A multi-well adapted immunoprecipitation assay using radiolabelled recombinant CRMP5 protein, produced by coupled in vitro transcription/translation, was used for the detection of CRMP5 antibodies. Sera from 200 patients with SCLC, 73 patients with thymoma and myasthenia gravis (MG) and from 300 healthy blood donors were examined for CRMP5 antibodies. Positive sera were also examined by immunofluorescence and immune blots. The serological results were compared with disease severity of the patients with thymoma or SCLC. CRMP5 antibodies were detected in 10/200 (5%) of the SCLC, 9/73 (12%) of the thymomas and in 2/300 (0.6%) of the healthy controls by immunoprecipitation. The antibodies were less frequently detected by immunofluorescence or immune blots. There was no significant correlation between CRMP5 antibodies and disease severity. CRMP5 antibodies are more than twice as frequent, and the antibody levels are higher in patients with thymoma and MG than in patients with SCLC. The antibodies are correlated to these tumours, but not to disease severity.

Paraneoplastic neurological syndromes and onconeural antibodies: clinical and immunological aspects

Paraneoplastic neurological syndromes (PNS) are infrequent disorders that are associated with cancer. The syndromes are highly heterogeneous and often affect several areas of the nervous system. Among the most well-known syndromes are paraneoplastic encephalomyelitis, cerebellar degeneration, sensory neuronopathy, and Lambert-Eaton myastenic syndrome. There are various associated tumors, in particular small cell lung cancer, cancer of the breast and ovary, and thymoma. The onset of neurological symptoms often precedes the cancer diagnosis, and the recognition of a paraneoplastic syndrome should lead to immediate search for cancer. The etiology of the paraneoplastic syndromes is believed to be autoimmune. Antibodies to onconeural antigens, expressed in the tumor of the affected individual and in normal neurons, are found in many of the patients. These antibodies are useful markers for paraneoplastic etiology. The pathogenesis of the PNS is uncertain, but cellular immune responses are thought to be the main effector mechanism. The cornerstone of therapy is the identification and treatment of the underlying malignancy. In some of the disorders, immunosuppressive therapy is of additional benefit. The prognosis of the different PNS varies depending on the level of affection and the degree of neuronal death.

Ri antibodies in patients with breast, ovarian or small cell lung cancer determined by a sensitive immunoprecipitation technique

The presence of circulating antineuronal antibodies has been associated with paraneoplastic neurological syndromes (PNS). Ri antibodies are often associated with lung or breast cancer, but the prevalence of such antibodies in large cancer materials is largely unknown. We used a highly sensitive immunoprecipitation assay to study the level of Ri antibodies in blood samples from 200 patients with small cell lung cancer (SCLC), 253 patients with breast cancer and 557 patients with ovarian cancer. Two hundred blood donors and six Ri positive PNS patients served as controls. The recombinant antigen used in the immunoprecipitation assay was radiolabeled by a coupled in vitro transcription and translation (ITT) technique, enabling low levels of antibodies to be detected. None of the blood donors contained Ri antibodies, whereas all of the sera from the PNS patients were positive. Ri antibodies were present in 4.5% of the patients with SCLC, 0.8% of the patients with breast cancer and in 0.2% of the patients with ovarian cancer. Retesting of the Ri positive samples with immunofluorescense and immune blot showed that the immunoprecipitation technique was more sensitive than the other immune assays. Ri antibodies were not associated with PNS in the patients with breast or ovarian cancer. Neurological data were not available for the SCLC patients, but in these, Ri antibodies were not associated with survival.

Detection of Autoantibodies to the BTB-kelch Protein KLHL7 in Cancer Sera

The aim of the study was to search for novel targets of autoantibodies in patients with paraneoplastic neurological syndromes (PNS). PNS are mediated by immune reactions against autoantigen(s) shared by the cancer cells and the nervous system. By serological screening of a rat cerebellum cDNA expression library using anti-Hu-positive sera from three patients with paraneoplastic encephalomyelitis (PEM), we identified an open reading frame encoding an isoform of the BTB-kelch protein KLHL7. Immunohistochemical studies demonstrated that the KLHL7 protein is expressed in the nuclei of neurones, but not in other tissues including various cancers. However, the KLHL7 protein was detected in the nuclei of cancer cell lines. Antibodies to KLHL7 were detected by an immunoprecipitation assay in sera from 12 of 254 (4.7%) patients with various cancers and 2 of 170 blood donors (1.2%). None of 50 sera from patients with multiple sclerosis were positive for KLHL7 antibodies. Sixteen patients with classical PNS and anti-Hu or anti-Yo antibodies were also negative for KLHL7 antibodies. Seven cancer patients with KLHL7 antibodies had various signs of neurological disease that could be related to cancer, whereas the remaining five seropositive cancer patients had no clinical signs of possible PNS. The present results indicate that KLHL7 antibodies are associated with various cancers, and in some patients also with neurological disease. Whether KLHL7 antibodies can be used as paraneoplastic markers for PNS remains to be determined.

Yo antibodies in ovarian and breast cancer patients detected by a sensitive immunoprecipitation technique

Onconeural antibodies are found in patients with cancer and are associated with paraneoplastic neurological syndromes (PNS). The objective of the present study was to assess the frequency of Yo antibodies in ovarian and breast cancer using a sensitive immunoprecipitation technique, and to look for any association of Yo antibodies with neurological symptoms and prognostic factors. A multiwell adapted fluid-phase immunoassay using radiolabelled recombinant cerebellar degeneration related protein (cdr2), produced by coupled in vitro transcription/translation was used for the detection of Yo antibodies. This technique combines high specificity and sensitivity with high sample analysing capacity for the antibody in question. Sera or EDTA-blood from 810 ovarian (n = 557) and breast cancer (n = 253) patients were analysed for Yo antibodies by immunoprecipitation, as well as immunofluorescence and immune blots. Two hundred healthy blood donors and sera from 17 patients with paraneoplastic cerebellar degeneration and Yo antibodies served as controls. Immunoprecipitation was more sensitive in detecting Yo antibodies than immunofluorescence and immune blots. The prevalence of Yo antibodies was 13/557 (2.3%) in ovarian cancer and 4/253 (1.6%) in breast cancer using immunoprecipitation. Yo antibodies were not correlated with specific histological subgroups. The Yo index of ovarian cancer patients in FIGO stage IV was higher compared to FIGO stage I-III. The prevalence of Yo antibodies was 3 times higher in patients with stage III breast cancer than in stage I and II. Only 2/17 (11.8%) patients with Yo antibodies detected during the screen of 810 cancer patients had PNS. The results show that the prevalence of Yo antibodies is low in ovarian and breast cancer. Yo antibodies may be associated with advanced cancer, but less often with PNS.

An immunoprecipitation assay for the detection of onconeural antibodies

INTRODUCTION

Onconeural antibodies are found in some patients with cancer, and are associated with paraneoplastic neurological syndromes.

METHOD

A multi-well adapted fluid-phase immunoassay using radiolabelled recombinant onconeural proteins for the detection of onconeural antibodies is described.

RESULT AND CONCLUSION

This immunoprecipitation technique is more sensitive in detecting onconeural antibodies than immunohistochemistry and immune blots.

Pyridoxal phosphatase is a novel cancer autoantigen in the central nervous system

Autoantibodies against many proteins are common in sera from patients with various types of cancer. These antibodies are sometimes involved in the development of conditions associated with cancer, such as paraneoplastic neurologic disorders. We used a human brain cDNA expression library and serum from a paraneoplastic neurologic disorder patient to search for new autoantigens in the nervous system. Pyridoxal phosphatase was identified as a novel autoantigen. Expression studies showed that pyridoxal phosphatase was strongly expressed in various parts of the central nervous system. Sera contained antibodies against pyridoxal phosphatase in 22 of 243 (9.1%) patients with lung cancer and eight of 113 (7.1%) with other forms of cancer vs two of 88 (2.3%) healthy control subjects. In addition, 2-4% of patients with different autoimmune diseases had autoantibodies against pyridoxal phosphatase. None of the antipyridoxal phosphatase-positive patients were known to have a paraneoplastic neurologic disorder. Hence, autoantibodies against pyridoxal phosphatase correlate with cancer but not necessarily with the subset of patients with paraneoplastic neurological disorders although serum from such a patient was used to screen the cDNA library. This study showed that yet another enzyme involved in pyridoxal 5'-phosphate metabolism is an autoantigen. Thus, pyridoxal 5'-phosphate seems to be a common denominator for autoantigens involved in autoimmune diseases.