The nuclear receptor LXRα controls the functional specialization of splenic macrophages.

Macrophages are professional phagocytic cells that orchestrate innate immune responses and have considerable phenotypic diversity at different anatomical locations. However, the mechanisms that control the heterogeneity of tissue macrophages are not well characterized. Here we found that the nuclear receptor LXRα was essential for the differentiation of macrophages in the marginal zone (MZ) of the spleen. LXR-deficient mice were defective in the generation of MZ and metallophilic macrophages, which resulted in abnormal responses to blood-borne antigens. Myeloid-specific expression of LXRα or adoptive transfer of wild-type monocytes restored the MZ microenvironment in LXRα-deficient mice. Our results demonstrate that signaling via LXRα in myeloid cells is crucial for the generation of splenic MZ macrophages and identify an unprecedented role for a nuclear receptor in the generation of specialized macrophage subsets

RXRs control serous macrophage neonatal expansion and identity and contribute to ovarian cancer progression

Tissue-resident macrophages (TRMs) populate all tissues and play key roles in homeostasis, immunity and repair. TRMs express a molecular program that is mostly shaped by tissue cues. However, TRM identity and the mechanisms that maintain TRMs in tissues remain poorly understood. We recently found that serous-cavity TRMs (LPMs) are highly enriched in RXR transcripts and RXR-response elements. Here, we show that RXRs control mouse serous-macrophage identity by regulating chromatin accessibility and the transcriptional regulation of canonical macrophage genes. RXR deficiency impairs neonatal expansion of the LPM pool and reduces the survival of adult LPMs through excess lipid accumulation. We also find that peritoneal LPMs infiltrate early ovarian tumours and that RXR deletion diminishes LPM accumulation in tumours and strongly reduces ovarian tumour progression in mice. Our study reveals that RXR signalling controls the maintenance of the serous macrophage pool and that targeting peritoneal LPMs may improve ovarian cancer outcomes.This work was supported by a HFSP fellowship to M.C-A. (LT000110/2015-L/1), grants from the Spanish Ministerio de Ciencia e Innovación (MCI) (SAF2015-64287R, SAF2017-90604-REDT-NurCaMein, RTI2018-095928-B100), La Marató de TV3 Foundation (201605-32) and Comunidad de Madrid (MOIR-B2017/BMD-3684) to M.R, and the Formación de Profesorado Universitario (FPU17/01731) programme (MCI) to J.P. The CNIC is supported by the MCI and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Neutrophils instruct homeostatic and pathological states in naive tissues

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.S

A Neutrophil Timer Coordinates Immune Defense and Vascular Protection

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.We thank all members of the Hidalgo Lab for discussion and insightful comments; J.M. Ligos, R. Nieto, and M. Viton for help with sorting and cytometric analyses; I. Ortega and E. Santos for animal husbandry; D. Rico, M.J. Gomez, C. Torroja, and F. Sanchez-Cabo for insightful comments and help with transcriptomic analyses; V. Labrador, E. Arza, A.M. Santos, and the Microscopy Unit of the CNIC for help with microscopy; S. Aznar-Benitah, U. Albrecht, Q.-J. Meng, B. Staels, and H. Duez for the generous gift of mice; J.A. Enriquez and J. Avila for scientific insights; and J.M. Garcia and A. Diez de la Cortina for art. 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 Economia, 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).S

Expansion and Activation of CD103 + Dendritic Cell Progenitors at the Tumor Site Enhances Tumor Responses to Therapeutic PD-L1 and BRAF Inhibition

CILJ: iz dijela istraživanja komorbiditeta pušača u riziku nastanka KOPB-a u sklopu projekta MARKO utvrditi postoje li razlike između spolova u odnosu na stanovanje u urbanoj ili ruralnoj sredini te u odnosu na pušački staž prema GOLD klasifikaciji bolesti kod pušača. Naknadni cilj je bio utvrditi epidemiološke osobitosti kroničnih bolesti donjeg dišnog sustav (KBDDS) u Splitsko-dalmatinskoj županiji (SDŽ) u odnosu na Republiku Hrvatsku (RH). MATERIJAL I METODE: prvi istraživački dio završnog rada urađen je u vidu presječne studije po načelima projekta MARKO provedenog 2010.-2011. godine kod 124 izabrana ispitanika pušača dobi 20-64 godine bez prethodno utvrđene KOPB-i i drugih stanja koja bitno odudaraju od zdravog dijela populacije. Epidemiološke osobitosti Splitsko-dalmatinske županije je retrospektivna studije pobola i smrtnosti od KBDDS. U oba dijela završnog rada korišten je komparativni epidemiološki metod. Standardizacija stopa pobola i smrtnosti urađena je direktnom metodom prema Europskoj standardnoj populaciji 2013 (ESP 2013). Statistička značajnost izračunata je χ²-testom, Studentovim t-testom, stope su prikazane uz 95% CI (Confidence Interval), značajnost razlika na razini pouzdanosti P<0,05 ili većoj. REZULTATI: unatoč činjenici da je uzorak od 124 ispitanika sadašnjih i bivših pušača visoko probran od strane njihovih liječnika obiteljske medicine i da je to mali nereprezentativan uzorak bez punovrijedne kontrolne skupine moglo se utvrditi da po GOLD klasifikaciji nema značajnosti razlika između muškog i ženskog spola niti između urbanog i ruralnog područja za sve ispitanike. Međutim u raščlambi ispitanika podijeljenih obzirom na duljinu pušačkog staža do i preko 40 godina kod muškog spola te do 30 i preko 30 godina kod ženskog spola utvrđene su statistički značajne razlike. Kod ispitanika Grada Splita s većim pušačkim stažom uopće nema zdravih pušača kod oba spola dok je i simptomatskih pušača statistički značajno više (P<0,01). Po zastupljenosti komorbiditeta koji je zabilježen kod 73 ispitanika za devet utvrđenih bolesti/stanja prednjače hipertenzija i hiperlipidemija. Statistički značajno veći udio (%) ispitanika bez bolesti tzv. „zdravi pušači“ utvrđen je kod ruralnog stanovništva u općinama 66,7% vs. 31,0% (χ²-test=6,52; P<0,05). Ispitanici oba spola Grada Splita imali su statistički značajno veći udio zbira svih komorbiditeta nego stanovnici općina 92,9% vs. 66,7% (χ²-test=14,26; P<0,001) kao i statistički značajno veći udjel ispitanika s jednom bolešću (45,2%) u odnosu na ispitanike iz općina (8,3%) (χ²-test=7,96; P<0,01). Ovakva razlika posljedica je većih udjela kod muškog spola dok kod ženskog spola nema značajnosti razlika. U odnosu na ukupno stanovništvo SDŽ dobi 20-64 godine kod ispitanika pušača u riziku na nastanak KOPB-a statistički je značajno veći pobol od hipertenzije i peptičkog sindroma. Statstički je značajno manji pobol od afektivnih poremećaja dok kod dijabetes melitusa, miokardiopatije, bolesti štitanjače i reumatskih bolesti nema značajnosti razlika. Rezultati istraživanja sukladni su spoznajama iz epidemioloških razmatranja. Prosječna godišnja smrtnost od KBDDS u SDŽ u razdoblju 2007.-2015. godine 22,21/100.000 za oba spola statistički je značajno niža od prosječne godišnje smrtnosti za RH 37,50/100.000, a poglavito od prosječne godišnje smrtnosti stanovnika kontinentalnih županija RH 41,77/100.000. ZAKLJUČAK: Iz rezultata istraživanja, premda bez rezultata druge faze istraživanja, kao i rezultata epidemiološke raščlambe smrtnosti od KBDDS u SDŽ može se nedvojbeno i nepobitno zaključiti da je pušenje duhana predominantni uzrok pobola i smrtnosti od KBDDS a time i same KOPB-i. Unatoč dobrim rezultatima u RH i još boljim u SDŽ mnogo više se može postići radom na primarnoj prevenciji KBDDS, a to je stalna borba protiv duhanskog dima. Svi zdravstveni djelatnici moraju u tome sudjelovati i u narednim godinama što skorije doprinijeti smanjenju udjela pušača s jedne trećine na jednu četvrtinu ukupnog stanovništva. Posebno mjesto u tim nastojanjima pripada medicinskim sestrama prvostupnicama educiranima i pripremljenima za rad u zajednici na težišnoj zadaći primarnoj prevenciji KBDDS i raka pluća.AIM: The aim of the research is to determine according to the GOLD Classification of Smokers' Disease whether there are differences between the sexes in smoking time and it’s relation to housing in the urban or rural environment. This was the personal part of the research of the smoking co-morbidity and the risk of chronic obstructive pulmonary disease (COPD) development within the MARKO project. The ultimate goal was to establish the epidemiological characteristics of chronic diseases of the lower respiratory system (CDLRS) in the Split-Dalmatia County (SDC) in relation to the Republic of Croatia. MATERIAL AND METHODS: The personal research part of the final work was carried out in the form of a cross-sectional study on the principles of the MARKO project implemented in 2010-2011. There was 124 selected smokers aged 20-64, without previously established COPD and other conditions that significantly deviate from the healthy part of the population. The epidemiological features of the SDC are retrospective studies of mortality by CDLRS. In both parts of the final work a comparative epidemiological method was used. The standardization of mortality and mortality rates was done by a direct method according to the European Standard Population 2013 (ESP 2013). Statistical significance was calculated by the χ²-test, Student's t-test, with 95% CI (Confidence Interval), the significance of differences on the level of reliability P <0.05 or greater. THE RESULTS: Despite the fact that a sample of 124 current and ex-smokers tested by their family medicine practitioners and that this small, non-representative sample without a full-time control group it could be established according to GOLD classification that there is no significant difference between male and female gender or between urban and rural area for all respondents. However, in the analysis of the respondents divided by the length of smoking time up to and over 40 years in male sex and up to 30 and over 30 years in the female sex, statistically significant differences were found. There are no healthy smokers in both sexes at the time of the questioning of the City of Split with a higher smoking age, while the symptomatic smokers are statistically significantly higher (P <0.01). By the presence of comorbidity observed in 73 subjects for nine predetermined disease /states, hypertension and hyperlipidemia are leading ones. Statistically significantly higher proportion (%) of patients with no illness so called "Healthy smokers" were found in the rural population in the municipalities of 66.7% vs. 31.0% (χ²-test = 6.52, P <0.05). The subjects of both sexes of the City of Split had a statistically significantly higher proportion of all comorbidity than the inhabitants of the municipalities 92.9% vs. 66.7% (χ²-test = 14.26; P <0.001) as well as statistically significantly higher proportion of subjects with single disease (45.2%) compared to district respondents (8.3%) (χ²-test = 7.96; P <0.01). This difference is the result of higher share in male sex, while in the female gender there is no significant difference. Compared to the total population of the population aged 20-64 years in the smokers' risk of developing COPD, there is a statistically significant increase in the prevalence of hypertension and peptic syndrome. There is a statistically significant decrease in affective disorders, while there is no significant difference in diabetes mellitus, myocarditis, shingles and rheumatic diseases. The results of personal research are consistent with epidemiological considerations. Average annual mortality from CDLRS in SDC in the period 2007-2015 year 22.21 / 100.000 for both sexes is statistically significantly lower than the average annual mortality rate for Croatia 37.50 / 100.000, and especially from the average annual mortality rate of the continental counties of Croatia 41.77 / 100.000. CONCLUSION: From the results of the personal research, although without the results of the second phase of the research and the results of the epidemiological analysis of the mortality of CDLRS in the SDC, it can be conclusively and irrefutably state that tobacco smoking is the predominant cause of the disease and mortality of CDLRS and COPD itself. Despite the good results in the Republic of Croatia and even better in the SDC, much more can be achieved by working on primary prevention of CDLRS, which is a constant fight against tobacco smoke. All health professionals must participate in the coming years as soon as possible to reduce the share of smokers from one third to one quarter of the total population. A special place in these endeavors belongs to nurses who are educated and prepared for work in the community on the primary task of primary prevention of CDLRS and lung cancer

Expansion and Activation of CD103(+) Dendritic Cell Progenitors at the Tumor Site Enhances Tumor Responses to Therapeutic PD-L1 and BRAF Inhibition.

Large numbers of melanoma lesions develop resistance to targeted inhibition of mutant BRAF or fail to respond to checkpoint blockade. We explored whether modulation of intratumoral antigen-presenting cells (APCs) could increase responses to these therapies. Using mouse melanoma models, we found that CD103(+) dendritic cells (DCs) were the only APCs transporting intact antigens to the lymph nodes and priming tumor-specific CD8(+) T cells. CD103(+) DCs were required to promote anti-tumoral effects upon blockade of the checkpoint ligand PD-L1; however, PD-L1 inhibition only led to partial responses. Systemic administration of the growth factor FLT3L followed by intratumoral poly I:C injections expanded and activated CD103(+) DC progenitors in the tumor, enhancing responses to BRAF and PD-L1 blockade and protecting mice from tumor rechallenge. Thus, the paucity of activated CD103(+) DCs in tumors limits checkpoint-blockade efficacy and combined FLT3L and poly I:C therapy can enhance tumor responses to checkpoint and BRAF blockade. Immunity 2016 Apr 19; 44(4):924-38

The nuclear receptor LXRα controls the functional specialization of splenic macrophages.

Macrophages are professional phagocytic cells that orchestrate innate immune responses and have considerable phenotypic diversity at different anatomical locations. However, the mechanisms that control the heterogeneity of tissue macrophages are not well characterized. Here we found that the nuclear receptor LXRα was essential for the differentiation of macrophages in the marginal zone (MZ) of the spleen. LXR-deficient mice were defective in the generation of MZ and metallophilic macrophages, which resulted in abnormal responses to blood-borne antigens. Myeloid-specific expression of LXRα or adoptive transfer of wild-type monocytes restored the MZ microenvironment in LXRα-deficient mice. Our results demonstrate that signaling via LXRα in myeloid cells is crucial for the generation of splenic MZ macrophages and identify an unprecedented role for a nuclear receptor in the generation of specialized macrophage subsets

BRAF V600E-induced senescence drives Langerhans cell histiocytosis pathophysiology

Langerhans cell histiocytosis (LCH) is a potentially fatal condition characterized by granulomatous lesions with characteristic clonal mononuclear phagocytes (MNPs) harboring activating somatic mutations in mitogen-activated protein kinase (MAPK) pathway genes, most notably BRAFV600E. We recently discovered that the BRAFV600E mutation can also affect multipotent hematopoietic progenitor cells (HPCs) in multisystem LCH disease. How the BRAFV600E mutation in HPCs leads to LCH is not known. Here we show that enforced expression of the BRAFV600E mutation in early mouse and human multipotent HPCs induced a senescence program that led to HPC growth arrest, apoptosis resistance and a senescence-associated secretory phenotype (SASP). SASP, in turn, promoted HPC skewing toward the MNP lineage, leading to the accumulation of senescent MNPs in tissue and the formation of LCH lesions. Accordingly, elimination of senescent cells using INK-ATTAC transgenic mice, as well as pharmacologic blockade of SASP, improved LCH disease in mice. These results identify senescent cells as a new target for the treatment of LCH