Characterization of the Microenvironment in Positive and Negative Sentinel Lymph Nodes from Melanoma Patients

Abstract

Melanomas are aggressive skin tumors characterized by high metastatic potential. Our previous results indicate that Natural Killer (NK) cells may control growth of melanoma. The main defect of blood NK cells was a decreased expression of activating NCR1/NKp46 receptor and a positive correlation of NKp46 expression with disease outcome in stage IV melanoma patients was found. In addition, in stage III melanoma patients, we identified a new subset of mature NK cells in macro-metastatic Lymph nodes (LN). In the present studies, we evaluated the numbers of NK cells infiltrating primary cutaneous melanoma and analyzed immune cell subsets in a series of sentinel lymph nodes (SLN). First, we show that NKp46+ NK cells infiltrate primary cutaneous melanoma. Their numbers were related to age of patients and not to Breslow thickness. Then, a series of patients with tumor-negative or -positive sentinel lymph nodes matched for Breslow thickness of the cutaneous melanoma was constituted. We investigated the distribution of macrophages (CD68), endothelial cells, NK cells, granzyme B positive (GrzB+) cells and CD8+ T cells in the SLN. Negative SLN (SLN-) were characterized by frequent adipose involution and follicular hyperplasia compared to positive SLN (SLN+). High densities of macrophages and endothelial cells (CD34), prominent in SLN+, infiltrate SLN and may reflect a tumor favorable microenvironment. Few but similar numbers of NK and GrzB+ cells were found in SLN- and SLN+: NK cells and GrzB+ cells were not correlated. Numerous CD8+ T cells infiltrated SLN with a trend for higher numbers in SLN-. Moreover, CD8+ T cells and GrzB+ cells correlated in SLN- not in SLN+. We also observed that the numbers of CD8+ T cells negatively correlated with endothelial cells in SLN-. The numbers of NK, GrzB+ or CD8+ T cells had no significant impact on overall survival. However, we found that the 5 year-relapse rate was higher in SLN with higher numbers of NK cells.

NKp30 isoforms and NKp46 transcripts in metastatic melanoma patients: Unique NKp30 pattern in rare melanoma patients with favorable evolution

“…We also found that NK cells in SLN correlated with higher rate of relapses, supporting a tumor-promoting role of NK cells in SLN. 23 However, we also showed that metastatic lymph nodes contained NK subset CD56 bright CD16 C endowed with high lytic potential following activation by cytokines. 26 Depending of the disease stage localized or metastatic, lymph node NK cells may display different functions likely reflecting their recruitment from the tumor or their local activation.…”

“…We showed that NK cells infiltrated primary thick melanoma (more numerous in melanomas from aged patients) but their numbers did not impact survival. 23 In blood NK cells, we observed a progressive decrease of NKp46 expression level in patients with advanced melanoma and this alteration correlated with shorter duration of stage IV. 15 In addition, chemotherapy treated patients displayed distinct phenotypic modulations, 24 indicating that tumor progression and conventional chemotherapy may interfere with NK cell status in melanoma patients.…”

microRNA Expression in Sentinel Nodes from Progressing Melanoma Patients Identifies Networks Associated with Dysfunctional Immune Response

“…Few data are available on the prognostic value of the immunological status of the sentinel node, although several authors reported immunosuppressive changes occurring in the tumor-draining nodes [44,45,46]. We have recently observed that the transcriptional profiles of SNB of stage III patients distinguish melanoma patients with progressive disease [8], suggesting that the immunological setting in the SNB may anticipate the conditions of systemic immunity and provide prognostic information.…”

Immune biomarkers for prognosis and prediction of responses to immune checkpoint blockade in cutaneous melanoma

“…94,95 In primary tumors, NK cells are mainly found in the peritumoural margin and not in the tumor mass. 96 Recently, a unique NK cell population has been identified in metastatic lymph nodes, characterized by high CD56 and CD16 co-expression. These NK cells appear to lyse tumor cells more efficiently than blood-derived NK cells in the presence of IL-2 and IL-15.…”