[show abstract][hide abstract] ABSTRACT: BACKGROUND: Primary sinonasal mucosal melanomas are aggressive tumors with a poor clinical control by current treatments, raising the urgent need of novel strategies. METHODS: By fluorescence in situ hybridization (FISH), direct sequencing, and immunohistochemistry, we investigate the spectrum of molecular abnormalities in a cohort of 32 cases of primary sinonasal mucosal melanomas. RESULTS: We found that all primary sinonasal mucosal melanomas lack BRAF V600E mutation; in addition, they are characterized by somatic mutations of NRAS (22%) and KIT (12.5%), together with amplification of RREB1 (100%) and loss of MYB (76%). The large majority of cases showed KIT protein expression (96.9%). Among tumor suppressor genes, primary sinonasal mucosal melanomas showed loss of PTEN (48.1%) and p16/INK4a (55.2%). All tested cases showed expression of pAkt and pErk, suggesting a combined activation of PI3K/Akt and RAS-mitogen-activated protein kinase (MAPK) pathways. CONCLUSIONS: This molecular fingerprint strongly argues against the clinical efficacy of BRAF-inhibitors, but could candidate primary sinonasal mucosal melanomas to therapeutic strategies targeting RAS and KIT mutations or inhibiting PI3K-Akt-mTOR pathway. Head Neck, 2012.
[show abstract][hide abstract] ABSTRACT: The differentiation of bone marrow-derived progenitor cells into monocytes, tissue macrophages and some dendritic cell (DC) subtypes requires the growth factor CSF1 and its receptor, CSF1R. Langerhans cells (LCs) and microglia develop from embryonic myeloid precursor cells that populate the epidermis and central nervous system (CNS) before birth. Notably, LCs and microglia are present in CSF1-deficient mice but absent from CSF1R-deficient mice. Here we investigated whether an alternative CSF1R ligand, interleukin 34 (IL-34), is responsible for this discrepancy. Through the use of IL-34-deficient (Il34(LacZ/LacZ)) reporter mice, we found that keratinocytes and neurons were the main sources of IL-34. Il34(LacZ/LacZ) mice selectively lacked LCs and microglia and responded poorly to skin antigens and viral infection of the CNS. Thus, IL-34 specifically directs the differentiation of myeloid cells in the skin epidermis and CNS.
[show abstract][hide abstract] ABSTRACT: Viral infections have been linked to the onset of type I diabetes (T1D), with viruses postulated to induce disease directly by causing β cell injury and subsequent release of autoantigens and indirectly via the host type I interferon (IFN-I) response triggered by the virus. Consistent with this, resistance to T1D is associated with polymorphisms that impair the function of melanoma differentiation associated gene-5 (MDA5), a sensor of viral RNA that elicits IFN-I responses. In animal models, triggering of another viral sensor, TLR3, has been implicated in diabetes. Here, we found that MDA5 and TLR3 are both required to prevent diabetes in mice infected with encephalomyocarditis virus strain D (EMCV-D), which has tropism for the insulin-producing β cells of the pancreas. Infection of Tlr3-/- mice caused diabetes due to impaired IFN-I responses and virus-induced β cell damage rather than T cell-mediated autoimmunity. Mice lacking just 1 copy of Mda5 developed transient hyperglycemia when infected with EMCV-D, whereas homozygous Mda5-/- mice developed severe cardiac pathology. TLR3 and MDA5 controlled EMCV-D infection and diabetes by acting in hematopoietic and stromal cells, respectively, inducing IFN-I responses at kinetically distinct time points. We therefore conclude that optimal functioning of viral sensors and prompt IFN-I responses are required to prevent diabetes when caused by a virus that infects and damages the β cells of the pancreas.
The Journal of clinical investigation 03/2011; 121(4):1497-507. · 15.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: Molluscum contagiosum virus (MCV) infection induces self-limiting cutaneous lesions in an immunocompetent host that can undergo spontaneous regression preceded by local inflammation. On histology, a large majority of MCV-induced lesions are characterized by islands of hyperplastic epithelium containing infected keratinocytes and surrounded by scarce inflammatory infiltrate. However, spontaneous regression has been associated with the occurrence of a dense inflammatory reaction. By histology and immunohistochemistry, we identified MCV-induced lesions showing a dense inflammatory infiltrate associated with cell death in keratinocytes (inflammatory Molluscum contagiosum (I-MC)). In I-MC, hyperplastic keratinocytes were highly immunogenic as demonstrated by the expression of major histocompatibility complex class I and II molecules. Immune cell infiltration consisted of numerous cytotoxic T cells admixed with natural killer cells and plasmacytoid dendritic cells (PDCs). Accordingly, a type I IFN signature associated with PDC infiltration was demonstrated in both keratinocytes and inflammatory cells. Among the latter, a cell population resembling IFN-DC (CD123(+)CD11c(+)CD16(+)CD14(+)MxA(+)) was identified in proximity to islands of apoptotic keratinocytes. In vitro-generated IFN-DCs expressed a strong cytotoxic signature, as demonstrated by high levels of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FasL). This study establishes a previously unreported model to underpin the role of innate immune cells in viral immune surveillance.
Journal of Investigative Dermatology 02/2011; 131(2):426-34. · 6.19 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recent evidences suggest a significant role of Plasmacytoid dendritic cells (PDC) role in the pathogenesis of lupus erythematosus (LE) via production of type I IFN. Taking advantage on the availability of multiple reagents (CD123, BDCA2, and CD2ap) specifically recognizing PDC on fixed tissues, we investigated the occurrence of PDC in a cohort of 74 LE patients. The large majority of LE biopsies (67/74; 90.5%) showed cutaneous infiltration of PDC. PDC were more frequently observed (96.4 vs 72.2) and numerous in cutaneous LE compared to systemic LE (SLE) and correlated with the density of the inflammatory infiltrate (r=0.40; p<0.001). PDC reduction in SLE might be related to a broader tissue distribution of this cellular population, as indicated by their occurrence in kidneys in 11 out of 24 (45.8%) cases studied. The distribution of cutaneous PDC showed two distinct patterns. More commonly, PDC were observed within perivascular inflammatory nodules in the dermis, associated with CD208+ mature DC and T-bet+ cells [D-PDC]. A second component was observed along the dermal-epithelial junction [J-PDC], in association with cytotoxic T-cells in areas of severe epithelial damage. Notably, chemerin reactivity was observed in 64% of LE biopsies on endothelial cells and in the granular layer keratinocytes. Cutaneous PDC in LE strongly produced type I IFN, as indicated by the diffuse MxA expression, and the cytotoxic molecule granzyme B. This study confirms cutaneous PDC infiltration as hallmark of LE. The topographical segregation in D-PDC and J-PDC suggests a novel view of the role of these cells in skin autoimmunity.