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ESR Project 1:  Trib1/3 Regulation of adipocyte-iNKT-Treg axis

 imogen

Imogen Morris

My project will focus on the interplay and crosstalk between adipose tissue (AT), invariant natural killer cells (iNKT) and Treg cells. This axis has been identified as a key area for research because both iNKT cells and Tregs have been shown to play a role in obesity-induced insulin resistance (PMID: 22981538, 22863618, 19633656). Recently, adipocytes have been recognised as non-professional lipid antigen presenting cells (APCs), via CD1d, which activates iNKT cells (PMID: 24966328, 23149942). iNKT cells in turn are capable of communicating and activating Tregs (PMID: 23898038). The dysregulation of this axis, apparent in obesity, likely hinges on lipids presented by the adipocytes. Considering that TRIB3 is involved in lipolysis during fasting, via inactivating a key enzyme involved in fatty acid synthesis (acetyl-coenzyme A carboxylase; ACC) (PMID: 16794074), and differentiation of adipocytes (PMID: 17646392, 18187772) it is highly likely that the TRIB family pays an important role within this axis of interest.

Together this strongly suggests that understanding the interactions and resulting implications of a dysregulated axis will provide key insights into obesity and its resulting comorbidities, particularly diabetes type II.

My research will be divided into two streams which will ultimately feed into one another:

Primarily I will use a co-culture system (PMID: 22863618, 24966328) of 3T3-L1 cells with a stable knockdown of TRIB1 or TRIB 3 co-cultured with the DN32.3 iNKT cell line or primary mouse iNKT cells. Here we can assess how TRIB1/3 are involved in lipid antigen presentation and how this potentially altered presentation affects the subsequent activation of iNKT’s. Finally I will repeat these experiments in a stimulated obese co-culture condition (e.g. FFA, inflammatory cytokines). From this data I can identify key elements within this pathway which become dysregulated during the progression of obesity, and how the activation of iNKT cells is altered.

Secondly I will investigate the interaction between iNKTs and Tregs. For this I will perform Treg-iNKT co-culture assays, using Treg cells isolated from w/t, TRIB 1 /3 knock out mice together with the DN32.3 iNKT cell line or primary mouse iNKT cells. Proliferation of and cytokine production by iNKT cells and Treg suppressor functions will be examined as described (PMID: 23898038). Here I can observe how the priming of iNKT cells, via both lean and obese AT, affects the resulting axis relationship and inflammatory response.