Conventional type 1 dendritic cells protect against age-related adipose tissue dysfunction and obesity.

Conventional dendritic cells (cDCs) scan and integrate environmental cues in almost every tissue, including exogenous metabolic signals. While cDCs are critical in maintaining immune balance, their role in preserving energy homeostasis is unclear. Here, we showed that Batf3-deficient mice lacking conventional type 1 DCs (cDC1s) had increased body weight and adiposity during aging. This led to impaired energy expenditure and glucose tolerance, insulin resistance, dyslipidemia, and liver steatosis. cDC1 deficiency caused adipose tissue inflammation that was preceded by a paucity of NK1.1+ invariant NKT (iNKT) cells. Accordingly, among antigen-presenting cells, cDC1s exhibited notable induction of IFN-γ production by iNKT cells, which plays a metabolically protective role in lean adipose tissue. Flt3L treatment, which expands the dendritic cell (DC) compartment, mitigated diet-induced obesity and hyperlipidemia in a Batf3-dependent manner. This effect was partially mediated by NK1.1+ cells. These results reveal a new critical role for the cDC1-iNKT cell axis in the regulation of adipose tissue homeostasis.We are grateful to the Immunology, Ophthalmology, and ENT Department at the UCM for providing useful discussion and to Gillian Dunphy and Antonia Tomás for critically reading the manuscript. We thank the CNIC and UCM facilities. Funding: Work in the S.I. laboratory is funded by the Spanish Ministerio de Ciencia, Innovación (MICINN), Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER), RTI2018-094484-BI00, and RYC-2016-19463. EHG is the recipient of an FPI fellowship (PRE2019-087509) from the Spanish Ministry of Science and Innovation. Work in the DS laboratory is funded by the CNIC; the European Research Council (ERC-2016-Consolidator Grant 725091); the MICINN, AEI and FEDER (PID2019-108157RB); Comunidad de Madrid (B2017/BMD-3733 Immunothercan-CM); Atresmedia (Constantes y Vitales prize); and Fundació La Marató de TV3 (201723). Work in the G.S. laboratory receives funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n° ERC 260464, EFSD/Lilly European Diabetes Research Programme GS, 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (Investigadores-BBVA-2017) IN[17]_BBM_BAS_0066, MINECO-FEDER SAF2016-79126-R, EUIN2017-85875, Comunidad de Madrid IMMUNOTHERCAN-CM S2010/BMD-2326 and B2017/BMD-3733 and Fundación AECC. IN receives funding from EFSD/Lilly (2019), EFSD Rising star (2019), and JdC— Incorporation (IJC2018-035390-I). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the MICINN, and the Pro CNIC Foundation.S

Resistance to Experimental Visceral Leishmaniasis in Mice Infected With Leishmania infantum Requires Batf3

Unveiling the protective immune response to visceral leishmaniasis is critical for a rational design of vaccines aimed at reducing the impact caused by this fatal, if left untreated, vector-borne disease. In this study we sought to determine the role of the basic leucine zipper transcription factor ATF-like 3 (Batf3) in the evolution of infection with Leishmania infantum, the causative agent of human visceral leishmaniasis in the Mediterranean Basin and Latin America. For that, Batf3-deficient mice in C57BL/6 background were infected with an L. infantum strain expressing the luciferase gene. Bioluminescent imaging, as well as in vitro parasite titration, demonstrated that Batf3-deficient mice were unable to control hepatic parasitosis as opposed to wild-type C57BL/6 mice. The impaired microbicide capacities of L. infantum-infected macrophages from Batf3-deficient mice mainly correlated with a reduction of parasite-specific IFN-γ production. Our results reinforce the implication of Batf3 in the generation of type 1 immunity against infectious diseases.Ministerio de Ciencia e Innovación FISPI11/00095 and FISPI14/00366 (FEDER FUNDING) and the Fondo de Investigaciones Sanitarias (ISCIII-RETICRD16/0027/0008-FEDER). SI is funded by RYC-2016-19463 and RTI2018-343 094484-B-I00 from Ministerio de Ciencia e Innovación (FEDER FUNDING). Institutional grants from the Fundación Ramón Areces and Banco de Santander to the CBMS