Mechanisms of metabolic dysfunction in cancer-associated cachexia

Metabolic dysfunction contributes to the clinical deterioration observed in advanced cancer patients and is characterized by weight loss, skeletal muscle wasting, and atrophy of the adipose tissue. This systemic syndrome, termed cancer-associated cachexia (CAC), is a major cause of morbidity and mortality. While once attributed solely to decreased food intake, the present description of cancer cachexia is a disorder of multiorgan energy imbalance. Here we review the molecules and pathways responsible for metabolic dysfunction in CAC and the ideas that led to the current understanding.We are very grateful to Dr. Doug Hanahan, Dr. Anna Hupalow- ska, Dr. Graham Robertson, Dr. Martina Schweiger, Dr. Marta Shahbazi, Dr. Rudolf Zechner, and our laboratory colleagues Dr. Latifa Bakiri, Dr. Oezge Uluckan, and Dr. Sebastian Hasen- fuss for critical reading and comments on our manuscript. E.F. W. is supported by a grant from the Spanish Ministry of Economy (BFU2012-40230) and a European Research Council Advanced Grant (ERC FCK/2008/37)S

Role of bulge epidermal stem cells and TSLP signaling in psoriasis

Psoriasis is a common inflammatory skin disease involving a cross-talk between epidermal and immune cells. The role of specific epidermal stem cell populations, including hair follicle stem cells (HF-SCs) in psoriasis is not well defined. Here, we show reduced expression of c-JUN and JUNB in bulge HF-SCs in patients with scalp psoriasis. Using lineage tracing in mouse models of skin inflammation with inducible deletion of c-Jun and JunB, we found that mutant bulge HF-SCs initiate epidermal hyperplasia and skin inflammation. Mechanistically, thymic stromal lymphopoietin (TSLP) was identified in mutant cells as a paracrine factor stimulating proliferation of neighboring non-mutant epidermal cells, while mutant inter-follicular epidermal (IFE) cells are lost over time. Blocking TSLP in psoriasis-like mice reduced skin inflammation and decreased epidermal proliferation, VEGFα expression, and STAT5 activation. These findings unravel distinct roles of HF-SCs and IFE cells in inflammatory skin disease and provide novel mechanistic insights into epidermal cell interactions in inflammation.We thank Drs. M. Serrano and M. Perez-Moreno for the Gt(ROSA)26Sortrn4(ACTB-tdTomato,-EGFP)Luo/J and K15-Cre-PGR mouse lines. We are very grateful to Drs. M. Perez-Moreno, F. Real, O. Uluckan, L. Bakiri and the laboratory members of the Sibilia and Wagner groups for critical reading of the manuscript and valuable suggestions. We thank V. Bermeo, G. Medrano, S. Leceta, O. Grana, and M. Perez for their technical help and IT support. We acknowledge R. Paus laboratory members for the shipment of hair follicle samples. N.G.L. received funding from the People programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no 608765. A.I is funded by the Institute of Health Carlos III (PI16/01430). The Wagner laboratory was funded by a grant from the Spanish Ministry of Economy and competitiveness (SAF2015-70857RE, cofounded by the European Regional Development Fund) and is supported by the ERC (ERC-AdG 2016 CSI-Fun).S

Cutaneous Immune Cell-Microbiota Interactions Are Controlled by Epidermal JunB/AP-1

Atopic dermatitis (AD) is a multi-factorial skin disease with a complex inflammatory signature including type 2 and type 17 activation. Although colonization by S. aureus is common in AD, the mechanisms rendering an organism prone to dysbiosis, and the role of IL-17A in the control of S. aureus-induced skin inflammation, are not well understood. Here, we show several pathological aspects of AD, including type 2/type 17 immune responses, elevated IgE, barrier dysfunction, pruritus, and importantly, spontaneous S. aureus colonization in JunBΔep mice, with a large transcriptomic overlap with AD. Additionally, using Rag1-/- mice, we demonstrate that adaptive immune cells are necessary for protection against S. aureus colonization. Prophylactic antibiotics, but not antibiotics after established dysbiosis, reduce IL-17A expression and skin inflammation, examined using Il17a-eGFP reporter mice. Mechanistically, keratinocytes lacking JunB exhibit higher MyD88 levels in vitro and in vivo, previously shown to regulate S. aureus colonization. In conclusion, our data identify JunB as an upstream regulator of microbiota-immune cell interactions and characterize the IL-17A response upon spontaneous dysbiosis.We thank the Wagner lab for helpful suggestions and discussion throughout the evolution of this project, specifically Alvaro Ucero, Nuria Gago, and Liliana Mellor. We thank Vanessa Bermeo and Guillermo Medrano for help with animal husbandry and genotyping. O.U. was funded by the ECTS/Amgen Bone Biology Fellowship (2013-2016) and by the Spanish Ministry of Economy and Competitiveness (SAF2012-39670). B.R. and W.W. were funded by a Jesus-Serra visiting scientist grant. E.F.W. was funded by a European Research Council advanced grant (ERC FCK/2008/37).S

Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function.

Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways

Epidermal-specific deletion of CD44 reveals a function in keratinocytes in response to mechanical stress

CD44, a large family of transmembrane glycoproteins, plays decisive roles in physiological and pathological conditions. CD44 isoforms are involved in several signaling pathways essential for life such as growth factor-induced signaling by EGF, HGF or VEGF. CD44 is also the main hyaluronan (HA) receptor and as such is involved in HA-dependent processes. To allow a genetic dissection of CD44 functions in homeostasis and disease, we generated a Cd44 floxed allele allowing tissue- and time-specific inactivation of all CD44 isoforms in vivo. As a proof of principle, we inactivated Cd44 in the skin epidermis using the K14Cre allele. Although the skin of such Cd44Δker mutants appeared morphologically normal, epidermal stiffness was reduced, wound healing delayed and TPA induced epidermal thickening decreased. These phenotypes might be caused by cell autonomous defects in differentiation and HA production as well as impaired adhesion and migration on HA by Cd44Δker keratinocytes. These findings support the usefulness of the conditional Cd44 allele in unraveling essential physiological and pathological functions of CD44 isoforms.We are grateful to Professor Ben Wielockx (DIPP,Dresden, Germany) for help with the in vivo wound healing assay, to Professors Pierre Chambon and Daniel Metzger (IGBMC, Strasbourg, France) for the kind gift of the K14 Cre mice. We thank Karin Müller-Decker (DKFZ, Heidelberg, Germany) and Peter Angel (DKFZ) for their help with the TPA induction experiments. We are extremely grateful to the animal facility of our institute (ITG, KIT) and especially to Selma Huber for their help with animal experiments. We also want to thank R. Saffrich. (Department of Medicine V (Hematology, Oncology & Rheumatology, University of Heidelberg, Heidelberg) for technical assistance in time-lapse imaging. We are grateful to Julia Gutjahr (Laboratory for Immunological and Molecular Cancer Research, Salzburg, Austria) for her help with the immunohistological pictures. We also thank Ana Guío-Carrión (Spanish National Cancer Centre, Genes Development and Disease Group, Cancer Cell Biology Programme, Madrid, Spain) for technical assistance. MT and ASB thank the German Research Foundation (Collaborative Research Center, CRC 873 B07) for support. ASB thank C. Monzel (Laboratoire Physico-Chimie, Institut Curie, Paris, France) for assistance in data analysis. iCeMS is supported by World Premier International Research Center Initiative (WPI), MEXT (Japan). EFW and LB are supported by grants from the Spanish Ministry of Economy (BFU2012 – 40230, and SAF2015 – 70857, co-funded by the ERDF-EU)S