Influence of immune privilege on ocular tumor development

Heterogeneity and molecular landscape of melanoma: implications for targeted therapy

Uveal cancer (UM) offers a complex molecular landscape characterized by substantial heterogeneity, both on the genetic and epigenetic levels. This heterogeneity plays a critical position in shaping the behavior and response to therapy for this uncommon ocular malignancy. Targeted treatments with gene-specific therapeutic molecules may prove useful in overcoming radiation resistance, however, the diverse molecular makeups of UM call for a patient-specific approach in therapy procedures. We need to understand the intricate molecular landscape of UM to develop targeted treatments customized to each patient's specific genetic mutations. One of the promising approaches is using liquid biopsies, such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), for detecting and monitoring the disease at the early stages. These non-invasive methods can help us identify the most effective treatment strategies for each patient. Single-cellular is a brand-new analysis platform that gives treasured insights into diagnosis, prognosis, and remedy. The incorporation of this data with known clinical and genomics information will give a better understanding of the complicated molecular mechanisms that UM diseases exploit. In this review, we focused on the heterogeneity and molecular panorama of UM, and to achieve this goal, the authors conducted an exhaustive literature evaluation spanning 1998 to 2023, using keywords like "uveal melanoma, "heterogeneity". "Targeted therapies"," "CTCs," and "single-cellular analysis".

Upregulation of SLC12A3 and SLC12A9 Mediated by the HCP5/miR-140-5p Axis Confers Aggressiveness and Unfavorable Prognosis in Uveal Melanoma

Perturbation of solute carriers (SLCs) has been implicated in metabolic disorders and cancer, highlighting the potential for drug discovery and therapeutic opportunities. However, there is relatively little exploration of the clinical relevance and potential molecular mechanisms underlying the role of the SLC12 family in uveal melanoma (UVM). Here, we performed an integrative multiomics analysis of the SLC12 family in multicenter UVM datasets and found that high expression of SLC12A3 and SLC12A9 was associated with unfavorable prognosis. Moreover, SLC12A3 and SLC12A9 were highly expressed in UVM in vivo. We experimentally characterized the roles of these proteins in tumorigenesis in vitro and explored their association with the prognosis of UVM. Lastly, we identified the HCP5-miR-140-5p axis as a potential noncoding RNA pathway upstream of SLC12A3 and SLC12A9, which was associated with immunomodulation and may represent a novel predictor for clinical prognosis and responsiveness to checkpoint blockade immunotherapy. These findings may facilitate a better understanding of the SLCome and guide future rationalized development of SLC-targeted therapy and drug discovery for UVM.

N6-Methyladenosine Regulators and Related LncRNAs Are Potential to be Prognostic Markers for Uveal Melanoma and Indicators of Tumor Microenvironment Remodeling

Uveal melanoma (UM) is one of the most common malignant intraocular tumors in adults. Few studies have investigated the effect of N6-methyladenosine (m6A) RNA methylation regulators and related long noncoding RNAs (lncRNAs) on the tumor microenvironment (TME) and survival time of patients with UM. Based on the transcriptome and clinical data from The Cancer Genome Atlas, we systematically identified m6A regulators. Then, we constructed an m6A regulators-based signature to predict the prognostic risk using univariate and LASSO Cox analyses. The signature was then validated by performing Kaplan-Meier, and receiver operating characteristic analyses. Through the correlation analysis, m6A regulators-related lncRNAs were identified, and they were divided into different clustering subtypes according to their expression. We further assessed differences in TME scores, the survival time of patients, and immune cell infiltration levels between different clustering subtypes. Finally, we screened out the common immune genes shared by m6A-related lncRNAs and determined their expression in different risk groups and clustering subtypes. For further validation, we used single-cell sequencing data from the GSE139829 dataset to explore the expression distribution of immune genes in the TME of UM. We constructed a prognostic risk signature representing an independent prognostic factor for UM using 3 m6A regulators. Patients in the low-risk group exhibited a more favorable prognosis and lower immune cell infiltration levels than patients in the high-risk group. Two subtypes (cluster 1/2) were identified based on m6A regulators-related lncRNAs. The TME scores, prognosis, and immune cell infiltration have a marked difference between cluster 1 and cluster 2. Additionally, 13 common immune genes shared by 5 lncRNAs were screened out. We found that these immune genes were differentially expressed in different risk groups and clustering subtypes and were widely distributed in 3 cell types of TME. In conclusion, our study demonstrated the important role of m6A regulators and related lncRNAs in TME remodeling. The signature developed using m6A regulators might serve as a promising parameter for the clinical prediction of UM.

Identification of prognostic genes in uveal melanoma microenvironment

Background

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Many previous studies have demonstrated that the infiltrating of immune and stromal cells in the tumor microenvironment contributes significantly to prognosis.

Methods

Dataset TCGA-UVM, download from TCGA portal, was taken as the training cohort, and GSE22138, obtained from GEO database, was set as the validation cohort. ESTIMATE algorithm was applied to find intersection differentially expressed genes (DEGs) among tumor microenvironment. Kaplan-Meier analysis and univariate Cox regression model were performed on intersection DEGs to initial screen for potential prognostic genes. Then these genes entered into the validation cohort for validation using the same methods as that in the training cohort. Moreover, we conducted correlation analyses between the genes obtained in the validation cohort and the status of chromosome 3, chromosome 8q, and tumor metastasis to get prognosis genes. At last, the immune infiltration analysis was performed between the prognostic genes and 6 main kinds of tumor-infiltrating immune cells (TICs) for understanding the role of the genes in the tumor microenvironment.

Results

959 intersection DEGs were found in the UM microenvironment. Kaplan-Meier and Cox analysis was then performed in the training and validation cohorts on these DEGs, and 52 genes were identified with potential prognostic value. After comparing the 52 genes to chromosome 3, chromosome 8q, and metastasis, we obtained 21 genes as the prognostic genes. The immune infiltration analysis showed that Neutrophil had the potential prognostic ability, and almost every prognostic gene we had identified was correlated with abundances of Neutrophil and CD8+ T Cell.

Conclusions

Identifying 21 prognosis genes (SERPINB9, EDNRB, RAPGEF3, HFE, RNF43, ZNF415, IL12RB2, MTUS1, NEDD9, ZNF667, AZGP1, WARS, GEM, RAB31, CALHM2, CA12, MYEOV, CELF2, SLCO5A1, ISM1, and PAPSS2) could accurately identify patients' prognosis and had close interactions with Neutrophil in the tumor environment, which may provide UM patients with personalized prognosis prediction and new treatment insights.

Uveal melanoma: progress in molecular biology and therapeutics

Uveal melanoma (UM) is the most common intraocular malignancy in adults. So far, no systemic therapy or standard treatment exists to reduce the risk of metastasis and improve overall survival of patients. With the increased knowledge regarding the molecular pathways that underlie the oncogenesis of UM, it is expected that novel therapeutic approaches will be available to conquer this disease. This review provides a summary of the current knowledge of, and progress made in understanding, the pathogenesis, genetic mutations, epigenetics, and immunology of UM. With the advent of the omics era, multi-dimensional big data are publicly available, providing an innovation platform to develop effective targeted and personalized therapeutics for UM patients. Indeed, recently, a great number of therapies have been reported specifically for UM caused by oncogenic mutations, as well as other etiologies. In this review, special attention is directed to advancements in targeted therapies. In particular, we discuss the possibilities of targeting: GNAQ/GNA11, PLCβ, and CYSLTR2 mutants; regulators of G-protein signaling; the secondary messenger adenosine diphosphate (ADP)-ribosylation factor 6 (ARF6); downstream pathways, such as those involving mitogen-activated protein kinase/MEK/extracellular signal-related kinase, protein kinase C (PKC), phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (mTOR), Trio/Rho/Rac/Yes-associated protein, and inactivated BAP1; and immune-checkpoint proteins cytotoxic T-lymphocyte antigen 4 and programmed cell-death protein 1/programmed cell-death ligand 1. Furthermore, we conducted a survey of completed and ongoing clinical trials applying targeted and immune therapies for UM. Although drug combination therapy based on the signaling pathways involved in UM has made great progress, targeted therapy is still an unmet medical need.

Update on GNA Alterations in Cancer: Implications for Uveal Melanoma Treatment

Tumorigenesis is correlated with abnormal expression and activity of G protein-coupled receptors (GPCRs) and associated G proteins. Oncogenic mutations in both GPCRs and G proteins (GNAS, GNAQ or GNA11) encoding genes have been identified in a significant number of tumors. Interestingly, uveal melanoma driver mutations in GNAQ/GNA11 were identified for a decade, but their discovery did not lead to mutation-specific drug development, unlike it the case for BRAF mutations in cutaneous melanoma which saw enormous success. Moreover, new immunotherapies strategies such as immune checkpoint inhibitors have given underwhelming results. In this review, we summarize the current knowledge on cancer-associated alterations of GPCRs and G proteins and we focus on the case of uveal melanoma. Finally, we discuss the possibilities that this signaling might represent in regard to novel drug development for cancer prevention and treatment.

Differential modulation and prognostic values of immune-escape genes in uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular cancer in adults. In the present study, we aimed to characterize the immunological features of primary UM cancer and to provide an association with prognostic markers and outcome. Also, we assessed the influence of the microenvironment on the expression of inhibitory immune checkpoints in UM. Genes of interest included MHC Class I and Class II molecules, as well as inhibitory immune-checkpoints, i.e. PDL1, PDL2, B7-H3, B7-H4, TBFRSF6B, CD47, CD155, GAL9, HVEM and CD200. We observed significant lower levels of MHC genes in UM cells as compared to normal uveal melanocytes. Unexpectedly however, the expression levels of most of the analyzed inhibitory immune-checkpoint genes were not different in cancer cells as compared to normal melanocytes, with the exception of CD200 and HVEM, that resulted significantly reduced. On the other hand, PDL1 inversely correlated with OS, PFS and thickness of the tumor. Also, PDL1, along with PDL2, expression significantly increased under inflammatory conditions. Finally, for the first time, we propose a possible role for CD47 in the immune evasive properties of UM. We show here that CD47 is significantly upregulated by UM cells following inflammatory stimuli and that it represents a good independent predictor of disease progression. The results from this study may propel advances in the development of immune-based therapies for UM patients.

Abnormally expressed JunB transactivated by IL-6/STAT3 signaling promotes uveal melanoma aggressiveness via epithelial-mesenchymal transition

Uveal melanoma (UM) is the most common primary intraocular tumor in adults, and it carries a high risk of metastasis and mortality. Various proinflammatory cytokines have been found to be significantly increased in the aqueous humor or vitreous fluid of UM patients; however, the role of these cytokines in UM metastasis remains elusive. In the present study, we found that long-term interleukin (IL)-6 exposure promoted the migration and invasion of UM cells, diminished cell–cell adhesion, and enhanced focal adhesion. Moreover, IL-6 treatment decreased the membranous epithelial marker TJP1 and increased the cytoplasmic mesenchymal marker Vimentin. Further investigation demonstrated that JunB played a critical role in IL-6-induced UM epithelial–mesenchymal transition (EMT). In UM cells, the expression of JunB was significantly up-regulated during the IL-6-driven EMT process. Additionally, JunB induction occurred at the transcriptional level in a manner dependent on phosphorylated STAT3, during which activated STAT3 directly bound to the JunB promoter. Importantly, the knockdown of STAT3 prevented the IL-6-induced EMT phenotype as well as cell migration and invasion, whereas JunB overexpression recovered the attenuated aggressiveness of UM cells. Similarly, with IL-6 stimulation, the stable overexpression of JunB strengthened the migratory and invasive capabilities of UM cells and induced the EMT-promoting factors (Snail, Twist1, matrix metalloproteinase (MMP)-2, MMP-14, and MMP-19). Analysis of The Cancer Genome Atlas (TCGA) database indicated that JunB was positively correlated with IL-6 and STAT3 in UM tissues. The present study proposes an IL-6/STAT3/JunB axis leading to UM aggressiveness by EMT, which illustrates the negative side of inflammatory response in UM metastasis.

Focus on cutaneous and uveal melanoma specificities

Cutaneous melanoma (CM) and uveal melanoma (UM) derive from cutaneous and uveal melanocytes that share the same embryonic origin and display the same cellular function. However, the etiopathogenesis and biological behaviors of these melanomas are very different. CM and UM display distinct landscapes of genetic alterations and show different metastatic routes and tropisms. Hence, therapeutic improvements achieved in the last few years for the treatment of CM have failed to ameliorate the clinical outcomes of patients with UM. The scope of this review is to discuss the differences in tumorigenic processes (etiologic factors and genetic alterations) and tumor biology (gene expression and signaling pathways) between CM and UM. We develop hypotheses to explain these differences, which might provide important clues for research avenues and the identification of actionable vulnerabilities suitable for the development of new therapeutic strategies for metastatic UM.

The antihelminthic drug niclosamide effectively inhibits the malignant phenotypes of uveal melanoma in vitro and in vivo

Uveal melanoma (UM) is a lethal intraocular malignancy with an average survival of only 2~8 months in patients with hepatic metastasis. Currently, there is no effective therapy for metastatic UM. Here, we reported that niclosamide, an effective repellence of tapeworm that has been approved for use in patients for approximately 50 years, exhibited strong antitumor activity in UM cells in vitro and in vivo. We showed that niclosamide potently inhibited UM cell proliferation, induced apoptosis and reduced migration and invasion. p-Niclosamide, a water-soluble niclosamide, exerted potent in vivo antitumor activity in a UM xenograft mouse model. Mechanistically, niclosamide abrogated the activation of the NF-κB pathway induced by tumor necrosis factor α (TNFα) in UM cells, while niclosamide elevated the levels of intracellullar and mitochondrial reactive oxygen species (ROS) in UM cells. Quenching ROS by N-acetylcysteine (NAC) weakened the ability of niclosamide-mediated apoptosis. Matrix metalloproteinase 9 (MMP-9) knockdown by shRNA potentiated, while ectopic expression of MMP-9 rescued, the niclosamide-attenuated invasion, implying that MMP-9 is pivotal for invasion blockage by niclosamide in UM cells. Furthermore, our results showed that niclosamide eliminated cancer stem-like cells (CSCs) as reflected by a decrease in the Aldefluor⁺ percentage and serial re-plating melanosphere formation, and these phenotypes were associated with the suppressed Wnt/β-catenin pathway by niclosamide in UM. Niclosamide caused a dose- and time-dependent reduction of β-catenin and the key components [e.g., DVLs, phospho-GSK3β (S9), c-Myc and Cyclin D1] in the canonical Wnt/β-catenin pathway. Additionally, niclosamide treatment in UM cells reduced ATP and cAMP contents, and decreased PKA-dependent phosphorylation of β-catenin at S552 and S675 which determine the stability of β-catenin protein, suggesting that niclosamide may work as a mitochondrial un-coupler. Taken together, our results shed light on the mechanism of antitumor action of niclosamide and warrant clinical trial for treatment of UM patients.

Identification of an Immunogenic Subset of Metastatic Uveal Melanoma

PURPOSE

Uveal melanoma is a rare melanoma variant with no effective therapies once metastases develop. Although durable cancer regression can be achieved in metastatic cutaneous melanoma with immunotherapies that augment naturally existing antitumor T-cell responses, the role of these treatments for metastatic uveal melanoma remains unclear. We sought to define the relative immunogenicity of these two melanoma variants and determine whether endogenous antitumor immune responses exist against uveal melanoma.

EXPERIMENTAL DESIGN

We surgically procured liver metastases from uveal melanoma (n = 16) and cutaneous melanoma (n = 35) patients and compared the attributes of their respective tumor cell populations and their infiltrating T cells (TIL) using clinical radiology, histopathology, immune assays, and whole-exomic sequencing.

RESULTS

Despite having common melanocytic lineage, uveal melanoma and cutaneous melanoma metastases differed in their melanin content, tumor differentiation antigen expression, and somatic mutational profile. Immunologic analysis of TIL cultures expanded from these divergent forms of melanoma revealed cutaneous melanoma TIL were predominantly composed of CD8(+) T cells, whereas uveal melanoma TIL were CD4(+) dominant. Reactivity against autologous tumor was significantly greater in cutaneous melanoma TIL compared with uveal melanoma TIL. However, we identified TIL from a subset of uveal melanoma patients which had robust antitumor reactivity comparable in magnitude with cutaneous melanoma TIL. Interestingly, the absence of melanin pigmentation in the parental tumor strongly correlated with the generation of highly reactive uveal melanoma TIL.

CONCLUSIONS

The discovery of this immunogenic group of uveal melanoma metastases should prompt clinical efforts to determine whether patients who harbor these unique tumors can benefit from immunotherapies that exploit endogenous antitumor T-cell populations. Clin Cancer Res; 22(9); 2237-49. ©2015 AACR.

Long overall survival after dendritic cell vaccination in metastatic uveal melanoma patients

PURPOSE

To assess the safety and efficacy of dendritic cell vaccination in metastatic uveal melanoma.

DESIGN

Interventional case series.

METHODS

We analyzed 14 patients with metastatic uveal melanoma treated with dendritic cell vaccination. Patients with metastatic uveal melanoma received at least 3 vaccinations with autologous dendritic cells, professional antigen-presenting cells loaded with melanoma antigens gp100 and tyrosinase. The main outcome measures were safety, immunologic response, and overall survival.

RESULTS

Tumor-specific immune responses were induced with dendritic cell vaccination in 4 (29%) of 14 patients. Dendritic cell-vaccinated patients showed a median overall survival with metastatic disease of 19.2 months, relatively long compared with that reported in the literature. No severe treatment-related toxicities (common toxicity criteria grade 3 or 4) were observed.

CONCLUSIONS

Dendritic cell vaccination is feasible and safe in metastatic uveal melanoma. Dendritic cell-based immunotherapy is potent to enhance the host's antitumor immunity against uveal melanoma in approximately one third of patients. Compared with other prospective studies with similar inclusion criteria, dendritic cell vaccination may be associated with longer than average overall survival in patients with metastatic uveal melanoma.

Splenectomy promotes indirect elimination of intraocular tumors by CD8+ T cells that is associated with IFNγ- and Fas/FasL-dependent activation of intratumoral macrophages

Ocular immune privilege (IP) limits the immune surveillance of intraocular tumors as certain immunogenic tumor cell lines (P815, E.G7-OVA) that are rejected when transplanted in the skin grow progressively when placed in the anterior chamber of the eye. As splenectomy (SPLNX) is known to terminate ocular IP, we characterized the immune mechanisms responsible for rejection of intraocular tumors in SPLNX mice as a first step toward identifying how to restore tumoricidal activity within the eye. CD8(+) T cells, IFNγ, and FasL, but not perforin, or TNFα were required for the elimination of intraocular E.G7-OVA tumors that culminated in destruction of the eye (ocular phthisis). IFNγ and FasL did not target tumor cells directly as the majority of SPLNX IFNγR1(-/-) mice and Fas-defective lpr mice failed to eliminate intraocular E.G7-OVA tumors that expressed Fas and IFNγR1. Bone marrow chimeras revealed that IFNγR1 and Fas expression on immune cells was most critical for rejection, and SPLNX increased the frequency of activated macrophages (Mϕ) within intraocular tumors in an IFNγ- and Fas/FasL-dependent manner, suggesting an immune cell target of IFNγ and Fas. As depletion of Mϕs limited CD8 T cell-mediated rejection of intraocular tumors in SPLNX mice, our data support a model in which IFNγ- and Fas/FasL-dependent activation of intratumoral Mϕs by CD8(+) T cells promotes severe intraocular inflammation that indirectly eliminates intraocular tumors by inducing phthisis, and suggests that immunosuppressive mechanisms that maintain ocular IP interfere with the interaction between CD8(+) T cells and Mϕs to limit the immunosurveillance of intraocular tumors.

Biology of advanced uveal melanoma and next steps for clinical therapeutics

Uveal melanoma is the most common intraocular malignancy although it is a rare subset of all melanomas. Uveal melanoma has distinct biology relative to cutaneous melanoma, with widely divergent patient outcomes. Patients diagnosed with a primary uveal melanoma can be stratified for risk of metastasis by cytogenetics or gene expression profiling, with approximately half of patients developing metastatic disease, predominately hepatic in location, over a 15-yr period. Historically, no systemic therapy has been associated with a clear clinical benefit for patients with advanced disease, and median survival remains poor. Here, as a joint effort between the Melanoma Research Foundation's ocular melanoma initiative, CURE OM and the National Cancer Institute, the current understanding of the molecular and immunobiology of uveal melanoma is reviewed, and on-going laboratory research into the disease is highlighted. Finally, recent investigations relevant to clinical management via targeted and immunotherapies are reviewed, and next steps in the development of clinical therapeutics are discussed.

Ascorbate in aqueous humor augments nitric oxide production by macrophages

Immunosuppressive molecules within the aqueous humor (AqH) are thought to preserve ocular immune privilege by inhibiting proinflammatory NO production by macrophages (MΦs). Consistent with previous observations, we observed that although MΦs stimulated in the presence of AqH expressed NO synthase 2 (NOS2) protein, nitrite concentrations in culture supernatants, an indirect measure of NO production, did not increase. Interestingly, NOS2 enzymatic activity, as measured by the conversion of L-arginine (L-Arg) into L-citrulline, was augmented in lysates of MΦs stimulated in the presence of AqH. These data suggested that intracellular L-Arg may have been limited by AqH. However, we observed increased mRNA expression of the L-Arg transporter, cationic amino acid transporter 2B, and increased L-Arg uptake in MΦs stimulated in the presence of AqH. Arginases were expressed by stimulated Ms, but competition for L-Arg with NOS2 was excluded. Expression of GTP cyclohydrolase, which produces tetrahydrobiopterin (H(4)B), an essential cofactor for NOS2 homodimerization, increased after M stimulation in the presence or absence of AqH and NOS2 homodimers formed. Taken together, these data provided no evidence for inhibited NOS2 enzymatic activity by AqH, suggesting that a factor within AqH may have interfered with the measurement of nitrite. Indeed, we observed that nitrite standards were not measurable in the presence of AqH, and this effect was due to ascorbate in AqH. Controlling for interference by ascorbate revealed that AqH augmented NO production in MΦs via ascorbate, which limited degradation of H(4)B. Therefore, AqH may augment NO production in macrophages by stabilizing H(4)B and increasing intracellular L-Arg.

Epigenetic regulation of CXCR4 expression by the ocular microenvironment

PURPOSE

Expression of the chemokine receptor CXCR4 by tumors is associated with metastatic migration and invasion of tumor cells. The importance of CXCR4 expression by uveal melanomas in metastasis to the liver was recently demonstrated when injection of CXCR4-negative uveal melanoma cells into mice resulted in reduced liver metastasis compared with CXCR4-positive uveal melanoma cells. Factors in the eye can induce downregulation of genes by epigenetic mechanisms. This study examined whether epigenetic regulation by the ocular environment induced downregulation of CXCR4 expression.

METHODS

LS174T colon cancer cells were injected in the anterior chamber (AC), subcutaneously (SC), or in the spleen capsule to induce liver metastasis in immune-deficient mice. CXCR4 gene transcription was analyzed by RT-PCR, and protein expression was determined by flow cytometry. Methyltransferase and histone deacetylase activities were determined by ELISA. Treatment with either 5-Aza-2-deoxycytidine (5-Aza) or trichostatin A (TSA) was used to induce demethylation or inhibit histone deacetylases, respectively.

RESULTS

AC-derived LS174T cells showed lower CXCR4 gene expression compared with SC-, liver-derived, or wild-type tumor cells. AC-derived LS174T tumor cells expressed methyltransferase activity compared with SC-, liver-derived, and wild-type tumor cells. Deacetylase activity was elevated in AC-derived LS174T tumor cells compared with SC-derived, liver-derived, and wild-type tumor cells. Treatment of AC-derived LS174T tumor cells with 5-Aza upregulated CXCR4 expression. TSA treatment did not restore CXCR4 expression.

CONCLUSIONS

These studies demonstrate that ocular microenvironment factors induce methylation and downregulation of tumor CXCR4 expression.

Good news-bad news: the Yin and Yang of immune privilege in the eye

The eye and the brain are prototypical tissues manifesting immune privilege (IP) in which immune responses to foreign antigens, particularly alloantigens are suppressed, and even completely inhibited. Explanations for this phenomenon are numerous and mostly reflect our evolving understanding of the molecular and cellular processes underpinning immunological responses generally. IP is now viewed as a property of many tissues and the level of expression of IP varies not only with the tissue but with the nature of the foreign antigen and changes in the limited conditions under which privilege can operate as a mechanism of immunological tolerance. As a result, IP functions normally as a homeostatic mechanism preserving normal function in tissues, particularly those with highly specialized function and limited capacity for renewal such as the eye and brain. However, IP is relatively easily bypassed in the face of a sufficiently strong immunological response, and the privileged tissues may be at greater risk of collateral damage because its natural defenses are more easily breached than in a fully immunocompetent tissue which rapidly rejects foreign antigen and restores integrity. This two-edged sword cuts its swathe through the eye: under most circumstances, IP mechanisms such as blood-ocular barriers, intraocular immune modulators, induction of T regulatory cells, lack of lymphatics, and other properties maintain tissue integrity; however, when these are breached, various degrees of tissue damage occur from severe tissue destruction in retinal viral infections and other forms of uveoretinal inflammation, to less severe inflammatory responses in conditions such as macular degeneration. Conversely, ocular IP and tumor-related IP can combine to permit extensive tumor growth and increased risk of metastasis thus threatening the survival of the host.

Uveal melanoma: the inflammatory microenvironment

Uveal melanoma is a highly malignant intraocular tumor with quite homogeneous tumor tissue and a diffuse leukocytic infiltration. In contrast with many other malignancies, the presence of infiltrating macrophages and T cells is associated with a poor prognosis rather than a good one. The clear link between inflammation and cancer in this malignancy provides a paradigm for macrophage plasticity and function. Macrophages in uveal melanoma have an M2-like phenotype and are associated with the loss of one specific chromosome - monosomy 3. The central players involved in this process and discussed in this review include macrophages, T lymphocytes, chemokines and cytokines, including the macrophage-attraction molecules. When a tumor acquires the ability to release significant amounts of macrophage-attraction molecules it causes the expansion of a population of myeloid immature cells that may not only help the tumor to suppress immune reactions but also aid in the construction of new blood vessels for tumor growth. A better understanding of the molecular basis of a local myelomonocytic cell population will bring a better understanding of the immunopathology of this disease and will lead to therapeutic interventions in uveal melanoma. This review focuses on the roles of the local inflammatory microenvironment in the development and progression of uveal melanoma.

Ex vivo enrichment of circulating anti-tumor T cells from both cutaneous and ocular melanoma patients: clinical implications for adoptive cell transfer therapy

Tumor-infiltrating lymphocytes (TILs) have been successfully used for adoptive cell transfer (ACT) immunotherapy; however, due to their scarce availability, this therapy is possible for a limited fraction of cutaneous melanoma patients. We assessed whether an effective protocol for ex vivo T-cell expansion from peripheral blood mononuclear cells (PBMCs), suitable for ACT of both cutaneous and ocular melanoma patients, could be identified. PBMCs from both cutaneous and ocular melanoma patients were stimulated in vitro with autologous, irradiated melanoma cells (mixed lymphocyte tumor cell culture; MLTCs) in the presence of IL-2 and IL-15 followed by the rapid expansion protocol (REP). The functional activity of these T lymphocytes was characterized and compared with that of TILs. In addition, the immune infiltration in vivo of ocular melanoma lesions was analyzed. An efficient in vitro MLTC expansion of melanoma reactive T cells was achieved from all PBMC’s samples obtained in 7 cutaneous and ocular metastatic melanoma patients. Large numbers of melanoma-specific T cells could be obtained when the REP protocol was applied to these MLTCs. Most MLTCs were enriched in non-terminally differentiated T_EM cells homogeneously expressing co-stimulatory molecules (e.g., NKG2D, CD28, CD134, CD137). A similar pattern of anti-tumor activity, in association with a more variable expression of co-stimulatory molecules, was detected on short-term in vitro cultured TILs isolated from the same patients. In these ocular melanoma patients, we observed an immune infiltrate with suppressive characteristics and a low rate of ex vivo growing TILs (28.5% of our cases). Our MLTC protocol overcomes this limitation, allowing the isolation of T lymphocytes with effector functions even in these patients. Thus, anti-tumor circulating PBMC-derived T cells could be efficiently isolated from melanoma patients by our novel ex vivo enrichment protocol. This protocol appears suitable for ACT studies of cutaneous and ocular melanoma patients.

HLA antigen and NK cell activating ligand expression in malignant cells: a story of loss or acquisition

Malignant transformation of cells is often associated with changes in classical and non-classical HLA class I antigen, HLA class II antigen as well as NK cell activating ligand (NKCAL) expression. These changes are believed to play a role in the clinical course of the disease since these molecules are critical to the interactions between tumor cells and components of both innate and adaptive immune system. For some time, it has been assumed that alterations in the expression profile of HLA antigens and NKCAL on malignant cells represented loss of classical HLA class I antigen and induction of HLA class II antigen, non-classical HLA class I antigen and/or NKCAL expression. In contrast to these assumptions, experimental evidence suggests that in some cases dysplastic and malignant cells can acquire classical HLA class I antigen expression and/or lose the ability to express HLA class II antigens. In light of the latter findings as well as of the revival of the cancer immune surveillance theory, a reevaluation of the interpretation of changes in HLA antigen and NKCAL expression in malignant lesions is warranted. In this article, we first briefly describe the conventional types of changes in HLA antigen and NKCAL expression that have been identified in malignant cells to date. Second, we discuss the evidence indicating that, in at least some cell types, classical HLA class I antigen expression can be acquired and/or the ability to express HLA class II antigens is lost. Third, we review the available evidence for the role of immune selective pressure in the generation of malignant lesions with changes in HLA antigen expression. This information contributes to our understanding of the role of the immune system in the control of tumor development and to the optimization of the design of immunotherapeutic strategies for the treatment of cancer.