Project description:LTβR signaling is crucial for immune development, homeostasis, and inflammation. To identify new factors that influence the quality of LTβR function, we combined transcriptomics with WGCNA.
Project description:We used microarrays to profile gene expression changes following growth factor stimulation of primary human fibroblasts. We serum starved (0.1% serum) fibroblasts for 48 hrs and restimulated with 10% serum for 0, 2, 4, 6 and 8 hrs. Total RNA was extracted from 2 independent biological replicas for each time point and hybridized to expression arrays.
Project description:Background: Lymphotoxin signaling via the lymphotoxin-β receptor (LTβR) has been implicated in several biological processes, ranging from development of secondary lymphoid organs, maintenance of splenic tissue, host defense against pathogens, autoimmunity, and lipid homeostasis. The major transcription factor that is activated by LTβR crosslinking is NF-κB. Two signaling pathways have been described that result in the activation of classical p50-RelA and alternative p52-RelB NF-κB heterodimers. Results: Using microarray analysis, we investigated the transcriptional response downstream of the LTβR in mouse embryoni fibroblasts (MEF) and its regulation by the RelA and RelB subunits of NF-κB. We describe novel LTβR-responsive genes that are regulated by RelA and/or RelB. Interestingly, we found that the majority of LTβR-regulated genes require the presence of both RelA and RelB, suggesting significant crosstalk between the two NF-κB activation pathways. Gene Ontology (GO) analysis confirmed that LTβR-NF-κB target genes are predominantly involved in the regulation of immune responses. However, other biological processes, such as apoptosis/cell death, cell cycle, angiogenesis, and taxis were also regulated by LTβR signaling. Moreover, we show that activation of the LTβR inhibits the expression of a key adipogenic transcription factor, peroxisome proliferator activated receptor-γ (pparg), suggesting that LTβR signaling may interfere with adipogenic differentiation. Conclusions: Thus, microarray analysis of LTβR-stimulated fibroblasts revealed further insight into the transcriptional response of LTβR signaling and its regulation by the NF-κB family members RelA and RelB. Keywords: cell type comparison (wt vs relA-/- vs relB-/-) after genetic modification using a time course for each cell type (wt, relA-/-, relB-/-) two time points were analysed (0h as control and 10h) using 3 technical replicates resulting in 18 samples in total
Project description:Lymphotoxin β-receptor-signalling orchestrates lymphoid neogenesis and subsequent tertiary lymphoid structures (TLS) associated with severe chronic inflammatory diseases spanning multiple organ systems. How LTβR-signalling drives chronic tissue damage particularly in the lung, which mechanism(s) regulate this process, and whether LTβR-blockade might be of therapeutic value has remained unclear. Here we demonstrate increased lymphotoxin expression of LTbR-ligands on myeloid and adaptive and innate immune-cells, enhanced non-canonical NF-κB signalling and enrichment of LTβR-target gene expression in epithelial cells of lungs from patients and mice with smoking-associated chronic obstructive pulmonary disease (COPD). Accordingly, Therapeutic inhibition of LTβR-signalling in young and aged mice with COPD disrupted TLS, reverted lung tissue destruction, airway-fibrosis and systemic muscle wasting. Mechanistically, we identified that LTβR-signalling blockade leads to diminished cell-death, concomitantly reactivated endogenous Wnt/β-catenin-signalling in alveolar epithelial cells and reduced TGFβ-signalling in airways. These findings highlight LTβR as a viable therapeutic target against TLS induced tissue damage that translates into novel anti-inflammatory, regenerative strategies to treat COPD.
Project description:How LTβR-signalling drives chronic tissue damage particularly in the lung, which mechanisms regulate this process, and whether LTβR-blockade might be of therapeutic value has remained unclear. To study the mechanisms underlying LTβR-inhibition, a transcriptional analysis was performed on lung tissue from B6 mice exposed to cigarette smoke for 6 months and treated therapeutically with LTβR-Ig from 4 to 6 months compared to mice exposed to cigarette smoke for 6 months and treated with control Ig from 4 to 6 months and filtered air control. Single-cell RNA-Seq identified 24 distinct cell populations across >20,000 cells in lungs with distinct changes occurring upon cigarette smoke exposure and LTβR-Ig treatment.