Identity Noise and Adipogenic Traits Characterize Dermal Fibroblast Aging.

During aging, stromal functions are thought to be impaired, but little is known whether this stems from changes of fibroblasts. Using population- and single-cell transcriptomics, as well as long-term lineage tracing, we studied whether murine dermal fibroblasts are altered during physiological aging under different dietary regimes that affect longevity. We show that the identity of old fibroblasts becomes undefined, with the fibroblast states present in young skin no longer clearly demarcated. In addition, old fibroblasts not only reduce the expression of genes involved in the formation of the extracellular matrix, but also gain adipogenic traits, paradoxically becoming more similar to neonatal pro-adipogenic fibroblasts. These alterations are sensitive to systemic metabolic changes: long-term caloric restriction reversibly prevents them, whereas a high-fat diet potentiates them. Our results therefore highlight loss of cell identity and the acquisition of adipogenic traits as a mechanism underlying cellular aging, which is influenced by systemic metabolism.

GM-CSF Protects Macrophages from DNA Damage by Inducing Differentiation.

At inflammatory loci, pro-inflammatory activation of macrophages produces large amounts of reactive oxygen species (ROS) that induce DNA breaks and apoptosis. Given that M-CSF and GM-CSF induce two different pathways in macrophages, one for proliferation and the other for survival, in this study we wanted to determine if these growth factors are able to protect against the DNA damage produced during macrophage activation. In macrophages treated with DNA-damaging agents we found that GM-CSF protects better against DNA damage than M-CSF. Treatment with GM-CSF resulted in faster recovery of DNA damage than treatment with M-CSF. The number of apoptotic cells induced after DNA damage was higher in the presence of M-CSF. Protection against DNA damage by GM-CSF is not related to its higher capacity to induce proliferation. GM-CSF induces differentiation markers such as CD11c and MHCII, as well as the pro-survival Bcl-2A1 protein, which make macrophages more resistant to DNA damage.

Genomic profiling of pediatric ALK-positive anaplastic large cell lymphoma: a Children's Cancer and Leukaemia Group Study.

Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) is a T-cell malignancy in which ALK expression is a consequence of the t(2;5) or a variant translocation involving Chromosome 2. For the most part, this disease presents in the pediatric population and most, but not all, patients are successfully treated. Although the t(2;5) product nucleophosmin-ALK has been extensively studied for its transforming properties, very little is known regarding cooperative genetic mutations that may contribute to lymphomagenesis and may predict survival outcome, specifically in a purely pediatric population. We set out to determine the frequency and positions of genomic imbalances in this relatively rare disease. We collected biopsy material from 15 UK-resident children with ALK-expressing ALCL. We performed array comparative genomic hybridization at a resolution of 1 MB using DNA isolated from tumor tissue. Some of the more common genomic gains were confirmed by quantitative PCR. Regions of genomic gain were far more common than losses and were most often detected on chromosomes 1-4, 5-12, 14, and 17, with Chromosome 11 being the most frequent site of genomic imbalances. Patients with 14 or fewer imbalances had a lower overall 3-year survival (87.5-40%, P = 0.14) as did patients with gains in the regions of DDB1 or BIRC5. A range of genomic imbalances exist in ALK-expressing ALCL of a pediatric origin, with a greater number associated with poorer overall survival.

Myeloid p38α signaling promotes intestinal IGF-1 production and inflammation-associated tumorigenesis.

The protein kinase p38α plays a key role in cell homeostasis, and p38α signaling in intestinal epithelial cells protects against colitis-induced tumorigenesis. However, little is known on the contribution of p38α signaling in intestinal stromal cells. Here, we show that myeloid cell-specific downregulation of p38α protects mice against inflammation-associated colon tumorigenesis. The reduced tumorigenesis correlates with impaired detection in the colon of crucial chemokines for immune cell recruitment. We identify insulin-like growth factor-1 (IGF-1) as a novel mediator of the p38α pathway in macrophages. Moreover, using genetic and pharmacological approaches, we confirm the implication of IGF-1 produced by myeloid cells in colon inflammation and tumorigenesis. We also show a correlation between IGF-1 pathway activation and the infiltration of myeloid cells with active p38α in colon samples from patients with ulcerative colitis or colon cancer. Altogether, our results uncover an important role for myeloid IGF-1 downstream of p38α in colitis-associated tumorigenesis and suggest the interest in evaluating IGF-1 therapies for inflammation-associated intestinal diseases, taking into consideration IGF-1 signaling and immune cell infiltration in patient biopsies.

Measuring NLR Oligomerization IV: Using Förster Resonance Energy Transfer (FRET)-Fluorescence Lifetime Imaging Microscopy (FLIM) to Determine the Close Proximity of Inflammasome Components.

Intracellular signaling and cellular activation have been demonstrated to reside on multi-protein complexes rather than in isolated proteins. Consequently, techniques to resolve these complexes have gained much attention over the last few years. Förster Resonance Energy Transfer (FRET) coupled with Fluorescence Lifetime Imaging Microscopy (FLIM) is a powerful tool to discriminate direct interactions between two proteins within a multi-protein complex. Here, we present the use of FRET-FLIM as an experimental tool for the interpretation of the inflammasome composition. We also introduce some considerations required for the correct use of this technique and the control experiments that should be implemented.