PI3K isoform p110δ role was explored in ubiquitous or conditional PI3K-gene-targeted mice and with PI3K-selective inhibitors in models of gut inflammation in vivo and PRR-associated events in bone marrow-derived dendritic cells (DCs) in vitro.
The in vivo inactivation of p110δ rendered dysbiosis and a hyper-inflammatory state revealed by an exaggerated mucosal Th1/Th17 cytokine profile with increase in pro-inflammatory cytokines (IL-1β, IL-18 and IL-12p70) but significantly reduced anti-inflammatory cytokines levels (IL-10) in response to an infection.
At a molecular level, PRR-mediated activation of DCs defective in p110δ activity coordinated a defective production of intra-phagosomal reactive oxygen species (ROS) by NOX-2 enzyme, increasing caspase-1 mediated inflammasome activation, and defective activation of the effector non-canonical autophagy via defective coupling of RAC2-NOX2. Lack of p110δ PI3K activity also revealed inefficacy in promoting regulatory T cells proliferation in favour to INFγ-producing cells in response to microbial ligands, preventing Treg-dependent immune tolerance and favouring inflammation facilitating the development of colitis.
The results of the proposed research have led to the identification of a new role and mechanism of action of a lipid kinase molecule PI3K, in a p110δ isoform selective manner in 1. DC-intrinsic NOD2-dependent activation of autophagy and dampening of inflammasome activity, 2. DC-intrinsic anti-inflammatory role of NOD2 signalling in vitro and in vivo, 3. New NOD2-driven regulatory pathways to induce DC anti-inflammatory properties to protect mammalian organism from colitis, 4. New immunotherapeutic angle to generate anti-/pro-inflammatory DCs in vitro and in vivo.
The results were presented in National and International Scientific events such as Autophagy UK Network Meeting, UCL Partners III Symposium, Toll Editing Innate Immunity, London Inflammation Network and Autophagy in inflammation. They were also presented at a local level in the Biochemical Pharmacology Department meetings and William Harvey Research Institute seminars.
