Search

Clodronate liposomes (Clo-Lip) have been widely used to deplete mononuclear phagocytes (MoPh) to study the function of these cells in vivo. Here, we revisited the effects of Clo-Lip together with genetic models of MoPh deficiency, revealing that Clo-Lip exert their anti-inflammatory effects independent of MoPh. Notably, not only MoPh but also polymorphonuclear neutrophils (PMN) ingested Clo-Lip in vivo, which resulted in their functional arrest. Adoptive transfer of PMN, but not of MoPh, reversed the anti-inflammatory effects of Clo-Lip treatment, indicating that stunning of PMN rather than depletion of MoPh accounts for the anti-inflammatory effects of Clo-Lip in vivo. Our data highlight the need for a critical revision of the current literature on the role of MoPh in inflammation.

41 p.-7 fig., ICAP-1 regulates β1 integrin activation and cell adhesion. Here we used ICAP-1-null mice to study ICAP-1 potential involvement during immune cell development and function. Integrin α4β1-dependent adhesion was comparable between ICAP-1-null and control thymocytes, but lack of ICAP-1 caused a defective single positive (SP) CD8+ cell generation, thus unveiling an ICAP-1 involvement in SP thymocyte development. ICAP-1 bears a nuclear localization signal and we found it displayed a strong nuclear distribution in thymocytes. Interestingly, there was a direct correlation between the lack of ICAP-1 and reduced levels in SP CD8+ thymocytes of Runx3, a transcription factor required for CD8+ thymocyte generation. In the spleen, ICAP-1 was found evenly distributed between cytoplasm and nuclear fractions, and ICAP-1-/- spleen T and B cells displayed upregulation of α4β1-mediated adhesion, indicating that ICAP-1 negatively controls their attachment. Furthermore, CD3+ - and CD19+ -selected spleen cells from ICAP-1-null mice showed reduced proliferation in response to T and B cell stimuli, respectively. Finally, loss of ICAP-1 caused a remarkable decrease in marginal zone B cell frequencies and a moderate increase in follicular B cells. Together, these data unravel an ICAP-1 involvement in the generation of SP CD8+ thymocytes and in the control of marginal zone B cell numbers., This work was supported by grants SAF2017-85146-R and PID2020-116291RB-I00 from the Ministerio de Ciencia e Innovación (MICINN) to J.T, PID2019-105623RB-I00 from MICINN to M.L.T,BFU2013-48828-P from MICINN to Y.R.C., ERC Synergy Grant (2018) to R.F., RTI2018-095497-B-I00 from MICINN to A.H, and RTI2018-093938-B-I100 from MICINN and (RD16/0011/0002, TERCEL) from Instituto de Salud Carlos III to AGZ.

Cell detection and tracking applied to in vivo fluorescence microscopy has become an essential tool in biomedicine to characterize 4D (3D space plus time) biological processes at the cellular level. Traditional approaches to cell motion analysis by microscopy imaging, although based on automatic frameworks, still require manual supervision at some points of the system. Hence, when dealing with a large amount of data, the analysis becomes incredibly time-consuming and typically yields poor biological information. In this paper, we propose a fully-automated system for segmentation, tracking and feature extraction of migrating cells within blood vessels in 4D microscopy imaging. Our system consists of a robust 3D convolutional neural network (CNN) for joint blood vessel and cell segmentation, a 3D tracking module with collision handling, and a novel method for feature extraction, which takes into account the particular geometry in the cell-vessel arrangement. Experiments on a large 4D intravital microscopy dataset show that the proposed system achieves a significantly better performance than the state-of-the-art tools for cell segmentation and tracking. Furthermore, we have designed an analytical method of cell behaviors based on the automatically extracted features, which supports the hypotheses related to leukocyte migration posed by expert biologists. This is the first time that such a comprehensive automatic analysis of immune cell migration has been performed, where the total population under study reaches hundreds of neutrophils and thousands of time instances. This work has been partially supported by the National Grant TEC2017-84395-P of the Spanish Ministry of Economy and Competitiveness, Madrid Regional Government and Universidad Carlos III de Madrid through the project SHARON-CM-UC3M, RTI2018-095497-B-I00 from Ministerio de Ciencia e Innovación (MICINN) and HR17_00527 from Fundación La Caixa to A.H. M.M-M. is supported by the Spanish Ministry of Education, Culture and Sports FPU Grant FPU18/02825. M.P-S. is supported by a Federation of European Biochemical Societies long-term fellowship. J.S. is supported by a fellowship (PRE2019-089130) from MICINN. Publicado

ICAP-1 regulates β1-integrin activation and cell adhesion. Here, we used ICAP-1-null mice to study ICAP-1 potential involvement during immune cell development and function. Integrin α4β1-dependent adhesion was comparable between ICAP-1-null and control thymocytes, but lack of ICAP-1 caused a defective single-positive (SP) CD8

Transcriptional and proteomic profiling of individual cells have revolutionized interpretation of biological phenomena by providing cellular landscapes of healthy and diseased tissues1,2. These approaches, however, do not describe dynamic scenarios in which cells continuously change their biochemical properties and downstream 'behavioural' outputs3-5. Here we used 4D live imaging to record tens to hundreds of morpho-kinetic parameters describing the dynamics of individual leukocytes at sites of active inflammation. By analysing more than 100,000 reconstructions of cell shapes and tracks over time, we obtained behavioural descriptors of individual cells and used these high-dimensional datasets to build behavioural landscapes. These landscapes recognized leukocyte identities in the inflamed skin and trachea, and uncovered a continuum of neutrophil states inside blood vessels, including a large, sessile state that was embraced by the underlying endothelium and associated with pathogenic inflammation. Behavioural screening in 24 mouse mutants identified the kinase Fgr as a driver of this pathogenic state, and interference with Fgr protected mice from inflammatory injury. Thus, behavioural landscapes report distinct properties of dynamic environments at high cellular resolution. This study was supported by RTI2018-095497-B-I00 from Ministerio de Ciencia e Innovación (MCIN), HR17_00527 from Fundación La Caixa, Transatlantic Network of Excellence (TNE-18CVD04) from the Leducq Foundation, and FET-OPEN (no. 861878) from the European Commission to A.H. M.P-S. is supported by a Federation of European Biochemical Societies and the EMBO ALTF (no. 1142-2020) long-term fellowships. J.S. is supported by a fellowship (PRE2019-089130) from MICINN and A.A.-C. is supported by fellowship CF/BQ/ DR19/11740022 from La Caixa Foundation. J.L.Y.L. was supported by A*STAR and a Juan de la Cierva JCI-2017-33136 Fellowship from MICINN. S.D.C. is a recipient of a Marie Sklodowska-Curie fellowship (749731). M.G. is supported by SAF2017-89116R-P from MCIN and HR18_00120 from la Fundación La Caixa. T.R.M. is supported by grant NIH AI163223, L.G.N. is supported by SIgN core funding from A*STAR, and G.F.C. is supported by MCIN/ AEI/10.13039/501100011033 (grant PID2019-110895RB-I00) and by Junta de Comunidades de Castilla-La Mancha (SBPLY/19/180501/000211). F.S.-C. is supported by MCIN (grant RTI2018- 102084-B-I00), O.S. is supported by the Leducq Foundation (TNE-18CVD04), F.D.-d.-M. is supported by MCIN (TEC2017-84395-P), and T.E.S. is supported by the National Cancer Institute, NIH grant CA233576. The CNIC is supported by the MCIN and the Pro-CNIC Foundation. Sí

Cardiomyocytes are subjected to the intense mechanical stress and metabolic demands of the beating heart. It is unclear whether these cells, which are long-lived and rarely renew, manage to preserve homeostasis on their own. While analyzing macrophages lodged within the healthy myocardium, we discovered that they actively took up material, including mitochondria, derived from cardiomyocytes. Cardiomyocytes ejected dysfunctional mitochondria and other cargo in dedicated membranous particles reminiscent of neural exophers, through a process driven by the cardiomyocyte's autophagy machinery that was enhanced during cardiac stress. Depletion of cardiac macrophages or deficiency in the phagocytic receptor Mertk resulted in defective elimination of mitochondria from the myocardial tissue, activation of the inflammasome, impaired autophagy, accumulation of anomalous mitochondria in cardiomyocytes, metabolic alterations, and ventricular dysfunction. Thus, we identify an immune-parenchymal pair in the murine heart that enables transfer of unfit material to preserve metabolic stability and organ function. Video Abstract: [Figure presented] A system of macrophages in the heart supports cardiomyocyte health by phagocytosing exopher particles ejected from cardiomyocytes that contain defective mitochondria, among other cellular contents., This study was supported by Intramural grants from the Severo Ochoa program (IGP-SO); grants SAF2015-71878-REDT and SAF2014-56819-R from the Ministerio de Ciencia e Innovacion (MICINN) to A.C.; European Research Council grant EU-rhythmy (ERC-ADG-2014-ID:669387) to S.G.P., and MATRIX (ERC-COG-2018-ID: 819775) to B.I.; L.G.N. is supported by SIgN core funding from A∗STAR; grant BFU2016-75144-R from the Ministry of Science and Innovation to J.A.B,; grants PGC2018-096486-B-I00 and RD16/0011/0019 (ISCIII) from MICINN, TNE-17CVD04 from the Leducq Foundation, and S2017/BMD-3875 from the Comunidad de Madrid to M.T; intramural grant TPC/O-SO and grants SAF2015-65633-R, RTI2018-099357-B-I00, and HFSP (RGP0016/2018) to J.A.E.; intramural grant IGP-SO to J.A.-C. and A.H.; BIO2017-83640-P and RYC-2014-16604 to J.A-C; grants PRB3 (IPT17/0019-ISCIII-SGEFI/ERDF, ProteoRed) from the Carlos III Institute of Health and Fondo de Investigaciones Sanitarias, BIO2015-67580-P and PGC2018-097019-B-I00 from MICINN to J.V.; RTI2018-096068 from MICINN, AFM, MDA, LaCaixa-HR17-00040, UPGRADE-H2020-825825, and European Research Council (ERC-741538) to P.M.C.; S2017/BMD-3867 RENIM-CM from the Comunidad de Madrid and cofunded with European structural and investment funds to M.D.; 120/C/2015-20153032 from Fundació la Marató de TV3, SAF2015-65607-R and RTI2018-095497-B-I00 from MICINN, HR17_00527 from La Caixa Foundation, and TNE-18CVD04 from the Leducq Foundation to A.H.; C.V.R. is a Howard Hughes Medical Institute Faculty Scholar; J.A.N-A is supported by fellowship SVP-2014-068595, A.V.L.-V. by SVP-2013-068089, L.E.-M. by FJCI-2016-29384, and A.R.-P. by BES-2016-076635, all from MICINN; and the CNIC International Postdoctoral Program (EU grant agreement 600396 to D.J.S.). The CNIC is supported by the MICINN and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MICINN award SEV-2015-0505).

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).

Summary Circadian rhythms control organismal physiology throughout the day. At the cellular level, clock regulation is established by a self-sustained Bmal1-dependent transcriptional oscillator network. However, it is still unclear how different tissues achieve a synchronized rhythmic physiology. That is, do they respond independently to environmental signals, or require interactions with each other to do so? We show that unexpectedly, light synchronizes the Bmal1-dependent circadian machinery in single tissues in the absence of Bmal1 in all other tissues. Strikingly, light-driven tissue autonomous clocks occur without rhythmic feeding behavior and are lost in constant darkness. Importantly, tissue-autonomous Bmal1 partially sustains homeostasis in otherwise arrhythmic and prematurely aging animals. Our results therefore support a two-branched model for the daily synchronization of tissues: an autonomous response branch, whereby light entrains circadian clocks without any commitment of other Bmal1-dependent clocks, and a memory branch using other Bmal1-dependent clocks to “remember” time in the absence of external cues.

Non-alcoholic fatty liver disease (NAFLD) is a major health problem and the main cause of liver disease in Western countries. Although NAFLD is strongly associated with obesity and insulin resistance, its pathogenesis remains poorly understood. The disease begins with an excessive accumulation of triglycerides in the liver, which stimulates an inflammatory response. Alternative p38 mitogen-activated kinases (p38γ and p38δ) have been shown to contribute to inflammation in different diseases. Here we demonstrate that p38δ is elevated in livers of obese patients with NAFLD and that mice lacking p38γ/δ in myeloid cells are resistant to diet-induced fatty liver, hepatic triglyceride accumulation and glucose intolerance. This protective effect is due to defective migration of p38γ/δ-deficient neutrophils to the damaged liver. We further show that neutrophil infiltration in wild-type mice contributes to steatosis development by means of inflammation and liver metabolic changes. Therefore, p38γ and p38δ in myeloid cells provide a potential target for NAFLD therapy.

Neutrophils enter tissues to mediate immunity and inflammation. Casanova-Acebes et al. show that migration into naive tissues is equally important. In the intestine, they provide remote support to hematopoietic niches, whereas in the lungs they regulate circadian transcription and metastasis., Immune protection relies on the capacity of neutrophils to infiltrate challenged tissues. Naive tissues, in contrast, are believed to remain free of these cells and protected from their toxic cargo. Here, we show that neutrophils are endowed with the capacity to infiltrate multiple tissues in the steady-state, a process that follows tissue-specific dynamics. By focusing in two particular tissues, the intestine and the lungs, we find that neutrophils infiltrating the intestine are engulfed by resident macrophages, resulting in repression of Il23 transcription, reduced G-CSF in plasma, and reinforced activity of distant bone marrow niches. In contrast, diurnal accumulation of neutrophils within the pulmonary vasculature influenced circadian transcription in the lungs. Neutrophil-influenced transcripts in this organ were associated with carcinogenesis and migration. Consistently, we found that neutrophils dictated the diurnal patterns of lung invasion by melanoma cells. Homeostatic infiltration of tissues unveils a facet of neutrophil biology that supports organ function, but can also instigate pathological states., Graphical Abstract

Neutrophils eliminate pathogens efficiently but can inflict severe damage to the host if they over-activate within blood vessels. It is unclear how immunity solves the dilemma of mounting an efficient anti-microbial defense while preserving vascular health. Here, we identify a neutrophil-intrinsic program that enabled both. The gene Bmal1 regulated expression of the chemokine CXCL2 to induce chemokine receptor CXCR2-dependent diurnal changes in the transcriptional and migratory properties of circulating neutrophils. These diurnal alterations, referred to as neutrophil aging, were antagonized by CXCR4 (C-X-C chemokine receptor type 4) and regulated the outer topology of neutrophils to favor homeostatic egress from blood vessels at night, resulting in boosted anti-microbial activity in tissues. Mice engineered for constitutive neutrophil aging became resistant to infection, but the persistence of intravascular aged neutrophils predisposed them to thrombo-inflammation and death. Thus, diurnal compartmentalization of neutrophils, driven by an internal timer, coordinates immune defense and vascular protection. Neutrophils display circadian oscillations in numbers and phenotype in the circulation. Adrover and colleagues now identify the molecular regulators of neutrophil aging and show that genetic disruption of this process has major consequences in immune cell trafficking, anti-microbial defense, and vascular health., This study was supported by Intramural grants from A∗STAR to L.G.N., BES-2013-065550 to J.M.A., BES-2010-032828 to M.C.-A, and JCI-2012-14147 to L.A.W (all from Ministerio de Economía, Industria y Competitividad; MEIC). Additional MEIC grants were SAF2014-61993-EXP to C.L.-R.; SAF2015-68632-R to M.A.M. and SAF-2013-42920R and SAF2016-79040Rto D.S. D.S. also received 635122-PROCROP H2020 from the European Commission and ERC CoG 725091 from the European Research Council (ERC). ERC AdG 692511 PROVASC from the ERC and SFB1123-A1 from the Deutsche Forschungsgemeinschaft were given to C.W.; MHA VD1.2/81Z1600212 from the German Center for Cardiovascular Research (DZHK) was given to C.W. and O.S.; SFB1123-A6 was given to O.S.; SFB914-B08 was given to O.S. and C.W.; and INST 211/604-2, ZA 428/12-1, and ZA 428/13-1 were given to A.Z. This study was also supported by PI12/00494 from Fondo de Investigaciones Sanitarias (FIS) to C.M.; PI13/01979, Cardiovascular Network grant RD 12/0042/0054, and CIBERCV to B.I.; SAF2015-65607-R, SAF2013-49662-EXP, and PCIN-2014-103 from MEIC; and co-funding by Fondo Europeo de Desarrollo Regional (FEDER) to A.H. The CNIC is supported by the MEIC and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505).

The beta 1-adrenergic-receptor (ADRB1) antagonist metoprolol reduces infarct size in acute myocardial infarction (AMI) patients. The prevailing view has been that metoprolol acts mainly on cardiomyocytes. Here, we demonstrate that metoprolol reduces reperfusion injury by targeting the haematopoietic compartment. Metoprolol inhibits neutrophil migration in an ADRB1-dependent manner. Metoprolol acts during early phases of neutrophil recruitment by impairing structural and functional rearrangements needed for productive engagement of circulating platelets, resulting in erratic intravascular dynamics and blunted inflammation. Depletion of neutrophils, ablation of Adrb1 in haematopoietic cells, or blockade of PSGL-1, the receptor involved in neutrophil-platelet interactions, fully abrogated metoprolol's infarct-limiting effects. The association between neutrophil count and microvascular obstruction is abolished in metoprolol-treated AMI patients. Metoprolol inhibits neutrophil-platelet interactions in AMI patients by targeting neutrophils. Identification of the relevant role of ADRB1 in haematopoietic cells during acute injury and the protective role upon its modulation offers potential for developing new therapeutic strategies. We are grateful to all the METOCARD-CNIC trial investigators and to Noemi Escalera for coordinating the clinical work and Maite D. Rodriguez for handling human samples (CNIC). Angel Macias and Barulio-Perez-Asenjo (CNIC) performed the MRI studies. Noelia A-Gonzalez (CNIC) supplied the LysM-GFP + mice. R.P. Khaton, J. Mateos and V. Zorita provided technical support and animal care. M. Casanova-Acebes gave advice on neutrophil isolation. J.M. Adrover for IVM technical advice. R. Doohan, A. Guijarro and A. Molina-Iracheta provided technical support in histology. A. M. Santos-Beneit helped with microscopy image analysis and movie editing. We also thank the CNIC Animal, Cellomics and Microscopy units for support. Simon Bartlett provided English editing. We are grateful to Eeva I. Soininen and Ana I. Castillo for their inconditional support and management of the grants supporting this work. This work was supported by a competitive grant from the Institute of Health Carlos III and the European Regional Development Fund (ERDF/FEDER) (PI10/02268, PI13/01979 \& RD12/0042/0054). R.F.-J. was the recipient of non-overlapping grants from the Institute of Health Carlos III and ERDF/FEDER (Rio Hortega fellowship) and the Fundacion Jesus Serra, the Fundacion Interhospitalaria de Investigacion Cardiovascular (FIC) and the CNIC (FICNIC fellowship). A.H. is funded by MINECO and ERDF/FEDER (SAF2015-65607-R) and Fundacio La Marato-TV3 (120/C/2015-20153032). The CNIC is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). Borja Ibanez is the 2010 Princess of Girona awardee in Science. Sí

The antimicrobial functions of neutrophils are facilitated by a defensive armamentarium of proteins stored in granules, and by the formation of neutrophil extracellular traps (NETs). However, the toxic nature of these structures poses a threat to highly vascularized tissues, such as the lungs. Here, we identified a cell-intrinsic program that modified the neutrophil proteome in the circulation and caused the progressive loss of granule content and reduction of the NET-forming capacity. This program was driven by the receptor CXCR2 and by regulators of circadian cycles. As a consequence, lungs were protected from inflammatory injury at times of day or in mouse mutants in which granule content was low. Changes in the proteome, granule content and NET formation also occurred in human neutrophils, and correlated with the incidence and severity of respiratory distress in pneumonia patients. Our findings unveil a 'disarming' strategy of neutrophils that depletes protein stores to reduce the magnitude of inflammation. We thank members of the Comparative Medicine Unit and Advanced Microscopy Unit at CNIC. This study was supported by Intramural grants from the Severo Ochoa program (IGP-SO), a grant from Fundació La Marató de TV3 (120/C/2015-20153032), grant SAF2015-65607-R from Ministerio de Ciencia, Investigacion y Universidades (MCIU) with cofunding from Fondo Europeo de Desarrollo Regional, grant RTI2018-095497-B-I00 from MCIU and HR17_00527 from Fundación La Caixa (to A.H.), and fellowship BES-2013-065550 from MCIU (to J.M.A.), fellowship from La Caixa Foundation (ID 100010434, code LCF/BQ/DR19/11740022, to A.A.-C.) and fellowship Health-PERIS 2016–2020 (to C.C.) Funds were also obtained from Instituto de Salud Carlos III (FIS PI17/01601, to I.L.) and SAF2015-68632-R from MCIU (to M.A.M.); Wellcome Trust Seed Award in Science (206103/Z/17/Z, to D.R.), SFB1123-A1/A10 from Deutsche Forschungsgemeinschaft and ERC-AdG 692511 (to C.W.); SAF2017-84494-C2-R and Programa Red Guipuzcoana de Ciencia, Tecnología e Información 2018-CIEN-000058-01 (to J.R.-C.). Work at CIC biomaGUNE was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency (MDM-2017-0720). C.W. is a van de Laar professor of atherosclerosis. The CNIC is supported by the MCIU and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505). Sí