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García-Silva et al. show for the first time that extracellular vesicles isolated from the exudative seroma obtained from the lymphatic drainage implanted in melanoma patients after lymphadenectomy can be interrogated for melanoma markers and BRAF mutations. Profiling the BRAFV600E mutation in this biofluid is a novel approach to predict disease relapse., Liquid biopsies from cancer patients have the potential to improve diagnosis and prognosis. The assessment of surrogate markers of tumor progression in circulating extracellular vesicles could be a powerful non-invasive approach in this setting. We have characterized extracellular vesicles purified from the lymphatic drainage also known as exudative seroma (ES) of stage III melanoma patients obtained after lymphadenectomy. Proteomic analysis showed that seroma-derived exosomes are enriched in proteins resembling melanoma progression. In addition, we found that the BRAFV600E mutation can be detected in ES-derived extracellular vesicles and its detection correlated with patients at risk of relapse., Graphical Abstract

EMILIN-1; Melanoma; Metàstasi EMILIN-1; Melanoma; Metástasis EMILIN-1; Melanoma; Metastasis Several studies have demonstrated that melanoma-derived extracellular vesicles (EVs) are involved in lymph node metastasis; however, the molecular mechanisms involved are not completely defined. Here, we found that EMILIN-1 is proteolyzed and secreted in small EVs (sEVs) as a novel mechanism to reduce its intracellular levels favoring metastasis in mouse melanoma lymph node metastatic cells. Interestingly, we observed that EMILIN-1 has intrinsic tumor and metastasis suppressive-like properties reducing effective migration, cell viability, primary tumor growth, and metastasis. Overall, our analysis suggests that the inactivation of EMILIN-1 by proteolysis and secretion in sEVs reduce its intrinsic tumor suppressive activities in melanoma favoring tumor progression and metastasis. The authors gratefully acknowledge the support of the following sources of funding: Fundación Ramon Areces, MINECO (SAF2014-54541-R), Ramón y Cajal Programme, Asociación Española Contra el Cáncer, Constantes y Vitales (ATRES MEDIA/AXA Foundation) and FERO Foundation. We are also grateful for the support of the support of the Translational NeTwork for the CLinical application of Extracellular VesicleS, TeNTaCLES. RED2018-102411-T (AEI/10.13039/501100011033) and MINECO-Severo Ochoa predoctoral program to support A.A.L thesis and short term stay in Italy to perform this study. The CNIO, certified as Severo Ochoa Excellence Centre, is supported by the Spanish Government through the Instituto de Salud Carlos III (ISCIII).

The human αβ T-cell receptor (TCR) is composed of a variable heterodimer (TCRαβ) and three invariant dimers (CD3γε, CD3δε, and ζζ/CD247). The role of each invariant chain in the stepwise interactions among TCR chains along the assembly is still not fully understood. Despite the high sequence homology between CD3γ and CD3δ, the clinical consequences of the corresponding immunodeficiencies (ID) in humans are very different (mild and severe, respectively), and mouse models do not recapitulate findings in human ID. To try to understand such disparities, we stably knocked down (KD) CD3D or CD3G expression in the human Jurkat T-cell line and analyzed comparatively their impact on TCRαβ assembly, transport, and surface expression. The results indicated that TCR ensembles were less stable and CD3ε levels were lower when CD3γ, rather than CD3δ, was scarce. However, both defective TCR ensembles were strongly retained in the ER, lacked ζζ/CD247, and barely reached the T-cell surface (30% vs. normal controls). CD3 KD of human T-cell progenitors followed by mouse fetal thymus organ cultures showed high plasticity in emerging immature polyclonal T lymphocytes that allowed for the expression of significant TCR levels which may then signal for survival in CD3γ, but not in CD3δ deficiency, and explain the immunological and clinical disparities of such ID cases., Ministerio de Economía y Competitividad (MINECO RTI2018-095673-B-I00 and PID2019-105623RB-I00), Comunidad Autónoma deMadrid (CAM B2017/BMD3673), and Asociación Española Contra el Cáncer (AECC PROYE20084REGU and CICPF18030TORI), Fundación Ramón Areces, and Fundación Unoentrecienmil. AM was supported by Complutense/Harvard University scholarship CT46/15 and AJ-R by MINECO scholarship BES-2012-055054

Tissue-resident macrophages display varying phenotypic and functional properties that are largely specified by their local environment. One of these functions, phagocytosis, mediates the natural disposal of billions of cells, but its mechanisms and consequences within living tissues are poorly defined. Using a parabiosis-based strategy, we identified and isolated macrophages from multiple tissues as they phagocytosed blood-borne cellular material. Phagocytosis was circadianally regulated and mediated by distinct repertoires of receptors, opsonins, and transcription factors in macrophages from each tissue. Although the tissue of residence defined the core signature of macrophages, phagocytosis imprinted a distinct antiinflammatory profile. Phagocytic macrophages expressed CD206, displayed blunted expression of Il1b, and supported tissue homeostasis. Thus, phagocytosis is a source of macrophage heterogeneity that acts together with tissue-derived factors to preserve homeostasis., This study was supported by Ministerio de Economia, Competitividad e Industria (MINECO) grants SAF2015-65607 and SAF2013-49662-EXP to A. Hidalgo; SVP-2014-068595 to J.A. Nicolás-Ávila; BES-2013–065550 to J.M. Adrover; JCI-2012-12659 to N. A-Gonzalez; and SAF2014-56819-R and SAF2015-71878-REDT to A. Castrillo. Grant CAM S2010/BMD-2350 RAPHYME to A. Castrillo; SAF2015-64287-R, SAF2015-71878-REDT (MINECO), and CardioNext-ITN-608027 (European Commission FP7) to M. Ricote; and R01 AI089824 (National Institutes of Health) to C.V. Rothlin. H.P. is supported by grants from MINECO (SAF2014-54541-R), ATRES-MEDIA – AXA, Asociación Española Contra el Cáncer, WHRI Academy, and Worldwide Cancer Research. The Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) is supported by the MINECO and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505).