Melanoma-associated retinopathy: a paraneoplastic autoimmune complication

Autoantibodies to transient receptor potential cation channel, subfamily M, member 1 in a Japanese patient with melanoma-associated retinopathy

PURPOSE

To report a case of melanoma-associated retinopathy (MAR) in a Japanese patient found to have autoantibodies to transient receptor potential cation channel, subfamily M, member 1 (TRPM1).

CASE

An 82-year-old man presented with blurred vision OS as well as night blindness and photopsia OU. Fundus photography, fluorescein angiography, and spectral domain-optical coherence tomography findings were essentially normal. Goldmann perimetry revealed a relative central scotoma, including the blind spot in the right eye, as well as a relative scotoma around a blind spot OS. The full-field scotopic electroretinograms showed a "negative-type" pattern OU, suggestive of extensive bipolar cell dysfunction. Systemic examination revealed that the patient had malignant melanoma of the anus with lung metastasis. Autoantibodies to TRPM1 were detected in the serum of the patient by immunoblot analysis. Vitreous opacity developed during follow-up. The visual symptoms and vitreous opacity of the patient were markedly improved after oral prednisolone therapy. The patient died as a result of widespread metastasis of the melanoma at 11 months after his first visit.

CONCLUSION

The present case is the first reported instance of MAR positive for autoantibodies to TRPM1 in an Asian patient.

Diagnostic features of the autoimmune retinopathies

The term autoimmune retinopathy encompasses a spectrum of rare autoimmune diseases that affect retinal function, often but not exclusively at the level of the photoreceptor. They typically present with painless visual loss, which may be accompanied by normal fundus examination. Some are progressive, often rapidly. They present a diagnostic challenge because there are no standardised clinical or laboratory based diagnostic criteria. Included within the spectrum are cancer-associated retinopathy, melanoma-associated retinopathy and presumed non-paraneoplastic autoimmune retinopathy. Differentiation from other retinopathies can be challenging, with overlap in symptoms, signs, and investigation findings, and an absence of pathognomonic features. However, technological developments in ophthalmic imaging and serological investigation over the past decade are adding novel dimensions to the investigation and classification of patients with these rare diseases. This review addresses the clinical, imaging, and serological features of the autoimmune retinopathies, and discusses the relative strengths and limitations of candidate diagnostic features.

Autoimmune retinopathy

PURPOSE OF REVIEW

Autoimmune retinopathy (AIR) is an immune-mediated disorder characterized by progressive visual loss, abnormal electroretinographic and visual field findings in the presence of circulating anti-retinal antibodies. This review highlights advances made toward understanding the pathophysiology, clinical manifestations, and trends in the management of AIR.

RECENT FINDINGS

The pathophysiology of AIR is likely antibody-mediated. AIR serum autoantibodies are variable in their size and retinal tissue they target and can also be present in healthy controls and multiple autoimmune diseases. Rarely, AIR may be associated with dysregulated self-tolerance mechanisms in the thymus. Despite progress in research, our understanding of AIR remains incomplete. Lack of standardized methods for anti-retinal antibody testing continues to challenge the interpretation of seropositivity. Conventional immunosuppressives have been further studied, and promising immunomodulatory therapies, such as targeted B-cell therapy, have been introduced. Newer imaging modalities such as fundus autofluorescence and spectral domain optical coherence tomography may be helpful in diagnosis, monitoring progression of disease and response to treatment.

SUMMARY

AIR is a rare but vision-threatening disease whose pathogenesis is poorly defined. Lack of standardized clinical or laboratory criteria further complicates the diagnosis and management. Despite recent progress, further basic science research into the autoimmune process is needed. Prospective controlled clinical trials with immunomodulatory therapy can help define future treatment paradigms.

Diagnosis of occult melanoma using transient receptor potential melastatin 1 (TRPM1) autoantibody testing: a novel approach

PURPOSE

To report the first case of melanoma-associated retinopathy (MAR) and underlying occult melanoma diagnosed based on the presence of serum transient receptor potential melastatin 1 (TRPM1) autoantibodies.

DESIGN

Interventional case report with basic science correlation.

PARTICIPANTS

One patient with MAR.

INTERVENTION

Testing for the presence of serum TRPM1 autoantibodies.

MAIN OUTCOME MEASURES

Diagnosis of an occult melanoma involving the axillary lymph nodes (unknown primary site) and MAR based on the presence of TRPM1 autoantibodies in the patient's serum.

RESULTS

The patient's clinical exam was remarkable for mild intraocular inflammation in both eyes and retinal hemorrhages with an apparent choroidal neovascularization in the left eye, which was confirmed by fluorescein angiography and indocyanine green angiography testing. Humphrey visual field 30-2 SITA-fast (Humphrey Visual Field Analyzer, Carl Zeiss Meditec, Inc, Dublin, CA) demonstrated diffuse depression in both eyes out of proportion to the clinical exams, prompting electroretinography testing that revealed an electronegative response. Dark-adapted thresholds were markedly elevated and mediated by cones. Due to concern for MAR, a systemic work-up for melanoma was performed by the primary care physician that was unrevealing. Given our continued clinical suspicion for MAR, the patient's serum was sent for evaluation for TRPM1 autoantibodies. The patient's serum applied to normal human retina exhibited positivity in the inner nuclear layer. Application of the patient's serum to wild-type and TRPM1 knockout mouse retina revealed strongly labeled bipolar cells in the wild-type retina, but not in the TRPM1 knockout retina, indicating TRPM1-dependent immunoreactivity. The antigen was confirmed as TRPM1 by labeling of TRPM1-transfected human embryonic kidney 293 cells. Additional systemic work-up prompted by this finding resulted in identification of an occult metastatic melanoma involving the axillary lymph nodes with an unknown primary site. The patient underwent surgical excision of the occult melanoma without evidence of other sites of metastases. He also received intravenous immunoglobulin therapy and his vision has stabilized.

CONCLUSIONS

This is the first reported case of a melanoma-associated retinopathy diagnosed utilizing the innovative approach of testing for serum TRPM1 autoantibodies.

Serum TRPM1 autoantibodies from melanoma associated retinopathy patients enter retinal on-bipolar cells and attenuate the electroretinogram in mice

Melanoma-associated retinopathy (MAR) is a paraneoplastic syndrome associated with cutaneous malignant melanoma and the presence of autoantibodies that label neurons in the inner retina. The visual symptoms and electroretinogram (ERG) phenotype characteristic of MAR resemble the congenital visual disease caused by mutations in TRPM1, a cation channel expressed by both melanocytes and retinal bipolar cells. Four serum samples from MAR patients were identified as TRPM1 immunoreactive by 1. Labeling of ON-bipolar cells in TRPM1+/+ but not TRPM1−/− mouse retina, 2. Labeling of TRPM1-transfected CHO cells; and 3. Attenuation of the ERG b-wave following intravitreal injection of TRPM1-positive MAR IgG into wild-type mouse eyes, and the appearance of the IgG in the retinal bipolar cells at the conclusion of the experiment. Furthermore, the epitope targeted by the MAR autoantibodies was localized within the amino-terminal cytoplasmic domain of TRPM1. Incubation of live retinal neurons with TRPM1-positive MAR serum resulted in the selective accumulation of IgG in ON-bipolar cells from TRPM1+/+ mice, but not TRPM1−/− mice, suggesting that the visual deficits in MAR are caused by the uptake of TRPM1 autoantibodies into ON-bipolar cells, where they bind to an intracellular epitope of the channel and reduce the ON-bipolar cell response to light.

Delayed presentation of melanoma-associated retinopathy and subsequent resolution with cytoreduction surgery

BACKGROUND

To present a case of melanoma-associated retinopathy (MAR) which manifested 26 months prior to a formal diagnosis of melanoma.

METHODS

Case report.

RESULTS

A 72-year-old female presented with bilateral continuous photopsia consistent with MAR of 7-months duration. At this point, visual function appeared normal with the exception of mildly impaired colour vision (10/17 Ishihara plates). The flash electroretinographic (ERG) revealed extinguished rod responses, a normal a-wave and reduced b-wave (electronegative ERG) on the maximal combined response, absent oscillatory potentials and broadened a-wave trough on the cone response. Multifocal ERG (mfERG) responses were delayed and demonstrated atypical morphology. Nineteen months after the initial presentation, her visual symptoms had progressed significantly with constant debilitating photopsia in combination with 13 kg weight loss. Biopsy of a now evident left axillary mass demonstrated a metastatic high-grade malignant melanoma. No primary was detected, and an axillary lymph node clearance was undertaken. Subsequently, visual symptoms resolved with corresponding improvement in the ERG over the next 18 months. Rod responses recovered such that the amplitude was at the lower limit of normal and the mfERG response delay lessened. Unfortunately, the melanoma recurred and the patient passed away 6 months later. Visual symptoms did not recur.

CONCLUSION

We present a case which demonstrates MAR may precede the formal diagnosis of melanoma by up to 26 months. The potential for improvement in the rod visual function persists over a period of years with normalisation of an electronegative waveform. In this case, cytoreductive surgery resulted in complete resolution of the MAR, which did not return even with a recurrence of the tumour.

Autoantibody against transient receptor potential M1 cation channels of retinal ON bipolar cells in paraneoplastic vitelliform retinopathy

Background

Paraneoplastic retinopathy is caused by the cross-reaction of neoplasm-directed autoantibodies against retinal antigens and results in retinal damage. Paraneoplastic vitelliform retinopathy, a presumed paraneoplastic retinopathy with features of atypical melanoma-associated retinopathy, has recently been reported in patients with metastatic melanoma. Ocular ultrastructure and its autoantibody localization of paraneoplastic vitelliform retinopathy are still indefinable. This is the first report of anti-transient receptor potential M1 antibody directly against human retinal bipolar dendritic tips in a melanoma patient with paraneoplastic vitelliform retinopathy.

Case presentation

We present a pair of postmortem eyes of an 80-year-old male with metastatic cutaneous melanoma, who developed paraneoplastic vitelliform retinopathy. The autopsied eyes were examined with light microscopy, immunohistochemistry, and transmission electron microscopy. Microscopically, the inner nuclear layer and outer plexiform layer were the most affected retinal structures, with local thinning. The lesions extended to the outer nuclear layer, resulting in focal retinal degeneration, edema, and atrophy. No active inflammation or melanoma cells were observed. Immunohistochemistry showed tightly compact bipolar cell nuclei (protein kinase C alpha/calbindin positive) with blur/loss of ON bipolar cell dendritic tips (transient receptor potential M1 positive) in diffusely condensed outer plexiform layer. The metastatic melanoma cells in his lung also showed immunoreactivity against transient receptor potential M1 antibody. Transmission electron microscopy illustrated degenerated inner nuclear layer with disintegration of cells and loss of cytoplasmic organelles. These cells contained many lysosomal and autophagous bodies and damaged mitochondria. Their nuclei appeared pyknotic and fragmentary. The synapses in the outer plexiform layer were extensively degenerated and replaced with empty vacuoles and disintegrated organelles.

Conclusion

This case provides a convincing histological evidence of melanoma-associated autoantibodies directly against transient receptor potential M1 channels that target the ON bipolar cell structures in the inner nuclear and outer plexiform layers in paraneoplastic vitelliform retinopathy.

Presumed melanoma-associated retinopathy (MAR): a presenting sign of primary small intestinal melanoma?

Melanoma-associated retinopathy is a paraneoplastic retinopathy associated mostly with cutaneous melanoma. In most cases it presents months to years after diagnosis of primary cutaneous melanoma was made or after recurrence. We describe a 55-year-old male patient who presented with symptoms of decreased vision and photopsia. Diagnosis of melanoma-associated retinopathy was made, but no primary cutaneous melanoma was found. 3 months later he developed intestinal perforation due to small intestinal melanoma.

External Qi of Yan Xin Qigong induces cell death and gene expression alterations promoting apoptosis and inhibiting proliferation, migration and glucose metabolism in small-cell lung cancer cells

Small-cell lung cancer (SCLC) is a highly malignant carcinoma with poor long-term survival. Effective treatment remains highly demanded. In the present study, we demonstrated that External Qi of Yan Xin Qigong (YXQ-EQ) exerted potent cytotoxic effect towards SCLC cell line NCI-H82 via induction of apoptosis. Global gene expression profiling identified 39 genes whose expression was altered by YXQ-EQ in NCI-82 cells. Among them, semi-quantitative RT-PCR and real-time qPCR analyses confirmed that the gene expression levels of apoptotic proteins death-associated protein kinase 2 and cell death-inducing DFFA-like effector b were upregulated, whereas that of oncoproteins DEK and MYCL1, cell migration-promoting proteins CD24 and integrin-alpha 9, and glycolytic enzyme aldolase A were downregulated. These findings suggest that YXQ-EQ may exert anticancer effect through modulating gene expression in a way that facilitates cancer cell apoptosis while represses proliferation, metastasis, and glucose metabolism.

Identification of autoantibodies against TRPM1 in patients with paraneoplastic retinopathy associated with ON bipolar cell dysfunction

Background

Paraneoplastic retinopathy (PR), including cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR), is a progressive retinal disease caused by antibodies generated against neoplasms not associated with the eye. While several autoantibodies against retinal antigens have been identified, there has been no known autoantibody reacting specifically against bipolar cell antigens in the sera of patients with PR. We previously reported that the transient receptor potential cation channel, subfamily M, member 1 (TRPM1) is specifically expressed in retinal ON bipolar cells and functions as a component of ON bipolar cell transduction channels. In addition, this and other groups have reported that human TRPM1 mutations are associated with the complete form of congenital stationary night blindness. The purpose of the current study is to investigate whether there are autoantibodies against TRPM1 in the sera of PR patients exhibiting ON bipolar cell dysfunction.

Methodology/Principal Findings

We performed Western blot analysis to identify an autoantibody against TRPM1 in the serum of a patient with lung CAR. The electroretinograms of this patient showed a severely reduced ON response with normal OFF response, indicating that the defect is in the signal transmission between photoreceptors and ON bipolar cells. We also investigated the sera of 26 patients with MAR for autoantibodies against TRPM1 because MAR patients are known to exhibit retinal ON bipolar cell dysfunction. Two of the patients were found to have autoantibodies against TRPM1 in their sera.

Conclusion/Significance

Our study reveals TRPM1 to be one of the autoantigens targeted by autoantibodies in at least some patients with CAR or MAR associated with retinal ON bipolar cell dysfunction.

Melanoma-associated retinopathy associated with intranasal melanoma

PURPOSE

To present a case of melanoma-associated retinopathy (MAR) associated with an intranasal melanoma.

CASE REPORT

A 77-year-old Japanese man visited us complaining of night blindness, blurred vision, and color vision difficulties in both eyes. His best-corrected visual acuity was 0.7 in the right and 1.0 in the left eyes. The rod response of the electroretinogram (ERG) was abolished, and the maximum response had a negative waveform. The a-wave of the single-flash cone response was square shaped, and the b-wave was delayed. The ON-response of the long-flash cone ERG was absent, but the OFF-response was preserved. A severe loss of retinal sensitivity was detected by static perimetry. Positron emission tomography showed no abnormal signs. Six months after the initial examination, an intranasal tumor was detected and surgically removed. The final diagnosis based on histopathology was malignant melanoma.

CONCLUSION

Our case demonstrates that MAR can be associated with an intranasal mucosal melanoma. Thus, in cases where the primary lesion cannot be identified in patients with MAR-like symptoms and signs, we recommend that preferential sites of mucosal melanomas be examined.

Autoantibodies in melanoma-associated retinopathy target TRPM1 cation channels of retinal ON bipolar cells

Melanoma-associated retinopathy (MAR) is characterized by night blindness, photopsias, and a selective reduction of the electroretinogram b-wave. In certain cases, the serum contains autoantibodies that react with ON bipolar cells, but the target of these autoantibodies has not been identified. Here we show that the primary target of autoantibodies produced in MAR patients with reduced b-wave is the TRPM1 cation channel, the newly identified transduction channel in ON bipolar cells. Sera from two well characterized MAR patients, but not from a control subject, stained human embryonic kidney cells transfected with the TRPM1 gene, and Western blots probed with these MAR sera showed the expected band size (∼180 kDa). Staining of mouse and primate retina with MAR sera revealed immunoreactivity in all types of ON bipolar cells. Similar to staining for TRPM1, staining with the MAR sera was strong in dendritic tips and somas and was weak or absent in axon terminals. This staining colocalized with GFP in Grm6-GFP transgenic mice, where GFP is expressed in all and only ON bipolar cells, and also colocalized with Gα(o), a marker for all types of ON bipolar cells. The staining in ON bipolar cells was confirmed to be specific to TRPM1 because MAR serum did not stain these cells in a Trpm1(-/-) mouse. Evidence suggests that the recognized epitope is likely intracellular, and the sera can be internalized by retinal cells. We conclude that the vision of at least some patients with MAR is compromised due to autoantibody-mediated inactivation of the TRPM1 channel.

Two mouse models for recoverin-associated autoimmune retinopathy

PURPOSE

Recoverin has been demonstrated to be one of the main causative antigenic retinal proteins common in many cases of autoimmune retinopathy (AIR). Strategies for producing two different AIR mouse models associated with anti-recoverin antibodies were tested.

METHODS

(1) Six-week-old female B6.MRL-Fal(lpr)/J mice (LPR) mice were immunized with recombinant recoverin three times at 2-4 week intervals. (2) Five-month-old Balb/cJ mice were injected with hybridoma cells designed to produce recoverin monoclonal antibodies. Anti-recoverin antibodies were analyzed by immunoblot and enzyme-linked immunosorbent assay (ELISA). Electroretinograms (ERG), histopathologic examination, and flow cytometric analysis were assessed.

RESULTS

High anti-recoverin antibody levels were achieved in both models, accompanied by significantly reduced scotopic and photopic responses on the ERGs. Retinal histology showed swollen cell bodies in the inner nuclear layer in recoverin-immunized LPR mice, while photoreceptor and outer nuclear layer swelling was observed in recoverin hybridoma cells injected into balb/cJ mice. Glial fibrillary acidic protein (GFAP) staining detected a marked increase of Müller cells and astrocyte reactive gliosis in both mouse models. Rhodopsin and S-opsin staining was similar to controls, while decreased numbers of bipolar cells were observed in both models. Complement component C1q and C3 deposits increased upon immunohistopathologic retinal staining in both models, while increased numbers of CD4+ and CD68+ cells from retinas were found upon flow cytometric analysis.

CONCLUSIONS

These two models had similar pathology in the retina, indicating the retinal antigens to recoverin antibody set off pathologic events that include leukocyte invasion, complement deposition, reactive gliosis in the retina, and selective retinal degeneration of inner nuclear layer neurons. These two AIR mouse models will allow for detailed pathologic investigation and testing of protein antigens associated with human AIR and can be used to test treatments. It is important to note that, since most AIR patients have multiple anti-retinal antibodies, it will be possible to study which antibodies are pathologic and which have no retinal pathologic effects. These models can also serve as an important research resource for studying the pathophysiology of specific retinal proteins by creating autoantibodies, which potentially will give a better understanding of retinal protein interactions.