WP5 - Molecular pathophysiology and immunregulation in chronic inflammatory diseases

WP coordinator: Lars Rönnblom

In COMBINE we are convinced that a proper study of the molecular pathogenesis and immunoregulation in inflammatory diseases requires a very good characterisation of genes, environment and overall immunity in our patients as well as opportunities to link such studies to appropriate animal models. We intend to make our infrastructure for human and animal studies available to molecular scientists both within and outside the consortium. We will provide extra support to innovative projects driven by scientists already within the consortium, and also recruit new young scientists into the field, who can now study human disease without having to build translational milieus by their own. Below follows examples of such projects that will be supported in the initial phase of COMBINE.

Translating knowledge of the interferon system into potential treatments for systemic inflammatory diseases, in particular SLE, Sjögren´s syndrome and myositis: A new model for the etiopathogenesis of SLE and other systemic rheumatic diseases (Sjögrens syndrome, subsets of myositis) has emerged during recent years, where induction of IFN-alpha is central. Lars Rönnblom´s group from Uppsala initiated this field, and several collaborative studies between partners in our consortium on the role of IFN-alpha in other CID:s (Sjögrens syndrome, myositis, pSS) have followed. Recently genetic work has supported the concept of IFN-alpha dependent etiologies, and the groups in our consortium have now identified several genetic polymorphisms within the type I IFN system, including tyrosine kinase 2 (TYK2), IFN regulatory factor 5 (IRF5) and STAT4 that are strongly associated with SLE. Studies will be directed towards understanding of critical initial events in triggering and maintenance of IFN-alpha production. We will also use the imminent availability of anti-IFN-alpha antibodies for early studies on the effects of this inhibition in vitro and in vivo.

Translating knowledge of microbe – host interactions in CID into treatment regimes. The potential of microbes to initiate and modify chronic inflammation is well documented and Andrej Tarkowski and collaborators, have demonstrated how microbial DNA may induce chronic inflammation and tissue destruction. Less known is known about the contribution of gut flora to chronic inflammation although recent data indicate that alterations of the composition of the gut flora may further fuel the inflammation. Sven Pettersson has demonstrated how gut flora can modulate barrier function via nuclear receptors and attenuate inflammation by uncoupling NFkB More recently there is exciting evidence that gut flora may influence serotonin levels and thus cognitive function by regulating enzymes intimately connected to degradation of tryptophane, the rate limiting amino acid for serotonin. We will analyse the signal transduction pathways that are used between normal gut flora or a pathogen and the host to identify components of microbes that tune immune functions. We will also delineate which pathways that are utilised in infectious arthritis to trigger bone destruction and investigate how different immunosuppressive and anti-bone resorptive treatments can be used in combination with antibiotics to stop destruction associated with infectious arthritis.

Translating knowledge of alarmins into potential strategies for treating chronic inflammation. A new class of molecules that trigger early reactions of the immune system to ‘danger’, has been defined over the last decade and recently named “alarmins”. Collaborative work in our consortium has made significant contributions to the understanding of the role of the alarmins, in particular resistin and HMGB1, in inflammatory diseases. The knowledge in this area has reached a state where a larger effort is warranted to investigate their role in the initiation of several CID. We will now further define the role of HMGB1 in the activation of antigen presenting cells, and thus the role of HMGB1 in triggering autoimmune encephalitis and arthritis. We will use newly produced neutralising monoclonal antibodies to HMGB1 to further dissect the role of HMGB1 in vivo in CID models and for preparing trials of humanised versions of these antibodies in human CID.

Oxidative burst and the NcF gene polymorphisms. A pioneering finding in the Holmdahl group has been the recognition that variant of genes which influence oxidative burst determine risk for autoimmune disease. This finding has now been further developed into a therapeutic principle where drugs (also under commercial development, see wp9) that stimulate oxidative burst can inhibit CID development in mice and rats. Interestingly, polymorphisms in this pathway were recently shown to be associated also with human disease. In collaboration between groups in COMBINE we will now further dissect the molecular pathways that were defined by the NcF polymorphisms in rodents as well as in humans, and investigate in detail the mode of action of the drugs that dramatically influence both oxidative burst and CID:s.

Translating knowledge of new pathways in the eicosanoid system in development and maintenance of chronic inflammation: Sweden has a long tradition in basic eicasanoid research and interference with this system is still the most used anti-inflammation treatment in the world. Not least due to the problems with cox-2 blockade, there is, however, a large need to translate basic knowledge about eicosanoids into new clinically useful therapies. One particularly promising such line has been pursued by Per-Johan Jakobsson in our consortium from the original description of prostaglandin E synthase. Inhibition of this enzyme has emerged as very promising possibility for treatment of inflammation without developing the adverse events associated with Cox2 inhibition. We will now expand the studies of prostaglandin E synthase functions into animal models of CID:s and atherosclerosis and into human disease in collaboration with clinical groups and animal model specialists in the consortium. This work will be a foundation for work directed towards inhibition of this enzyme by a small pharmaceutical company (see wp9).

Although autoantibodies are both useful tools in diagnostic and even prognostic rheumatology and contribute directly to disease manifestations, there is still a substantial lack of knowledge in the underlying adaptive immune responses leading to autantibody formation. General B and T cell targeted therapy have proven useful during the last years, and the hope is that we will be able to offer our patients more specific immunomodulation in the future.
With a focus on RA and the RA-specific anti-citrullinated protein antibodies, ACPA, we will study citrulline-specific B cells. Flow cytometry and antigen-specific ELISpot assays will be established to assess frequency, localization and phenotype of citrulline-specific B cells reactive to a panel of candidate antigens. As a next step such B cells will be cloned and their antibodies produced in vitro.