This project is to study the specific roles for NF-?B activation in macrophages and mesenchymal cells in the development of chronic inflammation with the generation of mice with targeted deletions of IKKß in fibroblasts and macrophages using Cre/lox-mediated gene targeting of IKKß.
Csf1r-Cre mice were crossed with Rosa26-LSL-RFP reporter mice to determine the tissue specificity of Cre expression and Cre-mediated recombination. Analysis of Rosa26Csf1r-RFP mice illustrates that Csf1r-Cre is expression in haematopoietic progenitors cells and thus both meyloid and lymphoid lineages express Cre.
Csf1r-Cre mice were crossed to Ikkßf/f mice, despite expression of Cre in lymphoid and myeloid lineages there was a specific expansion of myeloid cells in the bone marrow Ikkß?Csf1r mice. This illustrates a requirement for IKKß in the inhibition of myeloid progenitor proliferation and differentiation.
CD11c-Cre mice were crossed with Ikkßf/f mice to generate a targeted mutation in CD11c+ cells. Analysis of DC populations in Ikkß?Cd11c mice showed a specific loss of migratory dermal DC (migDC) in cutaneous LN, that was associated with reduced accumulation of regulatory T cells (Treg).
In summary, our studies so far have revealed two new and important roles for IKKß : 1. IKKß inhibits proliferation and differentiation of immature myeloid cells. 2. IKKß in DC is required for steady state accumulation of migratory DC in cutaneous LNs and expansion of Treg cells. Deletion of IKKß in DC results in autoimmunity.
We expect to submit the data from these studies for publication in an appropriate scientific journal shortly after completion of the project in 18 months. The results will also be presented at international scientific conferences.
Chronic inflammation - a failure to resolve?
Acute inflammation is the body’s first response to infection or injury and is a critical part of innate immunity and wound healing. However, chronic inflammation is linked with the development many human diseases including atherosclerosis, arthritis, asthma, Alzheimer’s disease and cancer. Our knowledge of the molecular and cellular processes that regulate the inflammatory response has greatly advanced in recent decades but we still do not understand the molecular control of acute versus chronic inflammation. Chronic inflammation is usually considered from the perspective of increased activation of pro-inflammatory pathways due to genetic polymorphism, infection, injury or persistence of an antigen, however inflammation is essentially a self-limiting response and although the mechanisms that drive the resolution of inflammation are still not well understood, it is clear that de-regulation these endogenous anti-inflammatory mechanisms may contribute to chronic inflammatory disease. Characterisation of the molecular mechanisms that drive the resolution of inflammation may give new insights into the pathogenesis of chronic inflammatory disease and new approaches to anti-inflammatory therapy.
NF-kappaB and inflammation.
The transcription factor; nuclear factor (NF)-kappaB, plays a central role in inflammation through the regulation pro-inflammatory gene expression and cell survival pathways. NF-kappaB activation in response to pro-inflammatory stimuli is regulated by IkappaB kinase (IKK) beta and thus IKKbeta has become a major target for development of new anti-inflammatory drugs. However, our studies also suggest a role for IKKbeta and NF-kappaB in the resolution of inflammation. We previously showed both pro- and anti-inflammatory roles for NF-kappaB in acute inflammation. More recently, using tissue-specific gene targeting of IKKß, we showed NF-kappaB activation in epithelial cells was required for leukocyte recruitment and inflammation in mouse models of asthma and pneumonia, however inhibition of IKKbeta specifically in macrophages increased inflammation. These studies suggest NF-kappaB has a cell-specific role in the inflammatory response and NF-kappaB activation specifically in macrophages regulates the resolution of inflammation.
Chronic inflammatory diseases such as rheumatoid arthritis (RA), scleroderma and systemic lupus erythematosus (SLE) are characterised by inflammation of connective tissue in the joints, skin and other organs. These diseases also have an autoimmune component and are driven by the inappropriate activation of immune cells that is linked to chronic inflammation. Various environmental and genetic factors have been suggested to contribute to RA and SLE but it is still not known what drives chronic inflammation and disease progression. In this proposal we will investigate the tissue-specific role of NF-kappaB in mouse models of inflammatory arthritis and lupus. Our hypothesis is; NF-?B activation in tissue mesenchymal cells drives chronic inflammation but NF-kappaB activation in macrophages promotes resolution of the inflammatory response. Targeting IKKbeta in mesenchymal cells may inhibit disease progression but we predict blockade of IKKbeta in macrophages will exacerbate disease. These studies will not only further our understanding of the role NF-kappaB plays in chronic inflammation but will also provide important information on the potential of NF-kappaB/IKK as a target for treatment of chronic inflammatory diseases including RA and SLE.
Monsieur Toby LAWRENCE (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE PROVENCE) – email@example.com
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
CNRS DR 12 - CIML CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE PROVENCE
Help of the ANR 270,000 euros
Beginning and duration of the scientific project: - 36 Months