Projects / Programmes
Inhibitors of cysteine carboxypeptidases as regulators of autoimmune and neurodegenerative processes
| Code |
Science |
Field |
Subfield |
| 4.06.01 |
Biotechnical sciences |
Biotechnology |
Recombinant DNA technology |
| Code |
Science |
Field |
| T490 |
Technological sciences |
Biotechnology |
| Code |
Science |
Field |
| 1.07 |
Natural Sciences |
Other natural sciences |
Cathepsin X, Gamma-enolase,LFA-1, Integrin, Protease inhibitor, Psoriasis, Neurodegenerative diseases
Researchers (29)
Organisations (4)
Abstract
We propose that inhibitors of cysteine carboxypeptidase cathepsin X reduce autoimmune and neurodegenerative processes as a result of the specific role this carboxypeptidase has in regulating integrin receptor LFA-1 and g-enolase. Cathepsin X is a lysosomal cysteine protease localized predominantly in immune and neuronal cells. We discovered recently that it may regulate the activity of lymphocyte function-associated antigen-1 (LFA-1), the predominant beta-2 integrin receptor in T cells that regulates T cell signalling, cytoskeletal remodelling, migration, the growth of cellular extensions like uropods and nanotubes, and formation of the immunological synapse. Excess activity of LFA-1 leads to autoimmune diseases such as psoriasis. Because the success of treatment of these diseases with existing drugs and protocols is very limited, LFA-1 is considered as an important and promising therapeutic target for new drug development. Several drugs have been developed to impair LFA-1 function, however, they are not appropriate for the therapy of autoimmune diseases due to insufficient selectivity against the harmful functions of LFA-1. General inhibition of LFA-1 activity may cause severe side effects, resulting in lethal infections in treated patients, as shown for efalizumab (Raptiva, Genentech), the first effective drug for treating psoriasis, which was recently withdrawn from the market. Our results show that cathepsin X enables fine regulation of LFA-1 activity by gradual degradation of the cytoplasmic tail of beta 2 chain of LFA-1, the part of the molecule that defines LFA-1 activity. In this way cathepsin X modulates the affinity of LFA-1 for some of its ligands, however, inhibition of cathepsin X does not completely impair LFA-1 activity, as is the case with efalizumab. This can be reflected in significantly reduced side effects. In neuronal cells, g-enolase is a target for cathepsin X. It is a glycolytic enzyme with additional functions in the proliferation of neuronal cells and neuritogenesis. Cathepsin X cleaves the C-terminal end of g-enolase, impairing the neurotrophic function of the latter. The cleavage prevents the binding of g-enolase to g1-syntrophin, a scaffold protein which is responsible for the translocation of g-enolase to the plasma membrane, a key step in its neurotrophic function. We recently demonstrated that inhibition of cathepsin X prevents the cleavage of g-enolase and increases the proliferation of neuronal cells and neuritogenesis, events which are very important for the treatment and prevention of neurodegenerative diseases. In this project we will use different approaches to select inhibitors of cathepsin X that are specific for the enzyme in targeted cells and non-toxic for other cells and tissues. Their selectivity and controlled release will be obtained by using delivery systems such as biodegradable polymeric nanoparticles. We will develop in vitro cell models using keratinocytes, T cells, neuronal cells and cells of microglia to resemble the pathological processes of psoriasis and neurodegenerative diseases. These models will be used to test the selected inhibitors and delivery systems. The most promising anti-cathepsin X compounds and formulations will be tested in vivo for their pharmacological properties.
Significance for science
The research in the proposed project is part of the advanced trends in science in the fields of proteolytic enzymes and processes of the immune response. Recent results obtained by our group on the regulation of integrin receptors in leukocytes, have opened up a new field of research, which has met with a wide and positive response in the scientific community, evidenced by multiple citations in journals with the highest impact factors. Further, some groups are continuing with the research, based on our results. Knowing the mechanisms of regulation of integrin receptors has enabled the basic processes in immune cells to be understood and may well explain the events leading to autoimmune diseases such as psoriasis. Our studies will define the role of cathepsin X in immune processes. This is very important if this protease is to be used as the target for the development of new drugs. Only selective inhibition of a particular protease that is truly involved in pathological processes, can lead to progress in therapy. The use of nonselective general protease inhibitors has been compromised, causing serious site effects. The therapeutic application of drugs that totally block the action of integrin receptors in immune cells is also inadequate, and some of them have had to be withdrawn from clinical practice. As an original scientific contribution we can draw attention to the newly revealed mechanism of action of cathepsin X on g-enolase and to the role of both proteins in the processes of neurodegeneration as well as the role of cathepsin X inhibitors and their ability to potentiate neurotrophic activity of g-enolase. Understanding the mechanisms of degeneration of neuronal cells and identification of molecular targets involved in these processes provides the essential basis for the development of new, effective drugs that are essential for treating neurodegenerative diseases. Within the proposed project we expect to prove that our approach of selective inhibition of integrin receptors in T cells with protease inhibitors enables fine regulation of their activity and reduces harmful site effects. The successful use of polymeric delivery systems will further limit the action of new drugs to cells that are involved in the pathological processes. Our project group will use the most recent techniques and methods that have already been introduced into laboratory practice. The collaboration with leading researchers in Slovenia and worldwide will guarantee rapid transfer of knowledge, good science and successful implementation of the project.
Significance for the country
ANG Medical treatment, health care and prevention are important elements in the socio-economic development of modern society, and every step towards better health is important. In particular, new knowledge and new drugs are essential for treating diseases where existing therapies are not effective, for example in autoimmune diseases and neurodegenerative diseases. The contribution of the proposed project was very important also for all levels of university education. It enabled students to acquire new knowledge and the project’s implementation provided opportunities for diploma and doctoral training in the fields of pharmaceutical biochemistry and biotechnology, since the members of the project team are involved in the pedagogical process at the University of Ljubljana and Postgraduate School Jožef Stefan, and as visiting professors at other universities. The results of this project will also foster our collaboration with other research groups, increasing knowledge exchange and the opportunity to obtain new European and other funds for financing our science.
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
