Investigation of cellular signaling pathways involved in macrophages tolerization in the tumor context

Abstract

Macrophages are immune system cells that are found in all tissues and have phagocytosis as one of their main activities. These cells can have different activation phenotypes depending on the microenvironment composition they are in. An important receptor present in these cells is TLR4, which recognizes patterns such as LPS and other endogenous antigens. Agonists action in this pathway results in NF-ºB, AP-1 and IRF3 activation, which are molecules associated with pro-inflammatory cytokines and chemokines. Another important pathway is PI3K/Akt/mTOR, which, among others outcomes, is related to changing macrophages's profile. Researches have shown that, when chronically exposed to an antigen, as in repetitive infections, these cells undergo a process called tolerization. In these cases, macrophages stop responding or respond in an inappropriate way to the referred antigen, which impairs the adequate assemble of the immune response. Tumor microenvironment is composed of several components that lead to a local dynamism, which favors damage associated molecular patterns (DAMP) release, which can activate TLR4. Although tumor microenvironment favors an immunoregulatory profile, it is not clear yet if there is a tolerized macrophage favoring. This project has the purpose of investigating how TLR and PI3K/Akt/mTOR pathways are associated with macrophages' tolerization when they undergo an endotoxin superexposition, and the relevance of this tolerization in a tumor context. To achieve this purpose, in vitro assays with stimulated macrophage in more than one moment will be performed and signaling pathways will be analyzed by Western Blot technique. Macrophages' phenotype will be also evaluated after tolerization induction (FACS). Once established LPS tolerization model, the ability of in vitro macrophage tolerization through tumor cells DAMPs derived stimuli will be assessed. Signaling pathway activation in this model will be verified, and, once changes in the pathways are found, we will try to revert the tolerized profile with the inhibitors or stimulators of these pathways. The development of this project can contribute with knowledge about macrophages actions in tumor microenvironment and identify possible therapeutic targets against cancer.