Elucidating Treg defects in ALS

About This Grant

1 There is a significant unmet need to identify disease ameliorating therapies for the treatment of ALS. It is 2 increasingly recognized that neuroinflammation plays a central role in driving the ALS progression. Regulatory 3 T cells (Tregs) are a lineage of CD4 T cells that regulate homeostasis by inhibiting inflammation and dampening 4 innate and adaptive immune cell activation. Human blood-derived Tregs can subdivided into two basic, 5 functionally distinct subsets: memory Tregs (mTregs) which have low proliferative capacity but induce strong 6 immediate ex vivo suppression; and resting/naive Tregs (nvTregs) which are highly proliferative, but weakly 7 suppressive without an ex vivo activation step, and represent the pool from which mTregs are theoretically 8 derived. Tregs have been found to be at lower frequency in ALS patients and exhibit reduced function in ALS 9 patients with faster rates of disease progression. In a proof of concept clinical trial, three patients received a Treg 10 adoptive cell therapy that could slow disease for a short period of time after each Treg ACT administration, 11 although the potential benefit was short-lived, suggesting these Tregs were inactivated by the disease 12 environment. Our proposal aims to identify why Tregs are functionally deficient in ALS and what events cause 13 their low frequency. Our studies using high parameter analyses and methods to test the activity of very low 14 numbers of cells, indicate that ALS-mTregs and nvTregs have distinct mechanisms of dysfunction. Thus, the 15 ALS-mTregs show both low frequency and poor stability in early disease, which would reduce their capacity to 16 function in vivo, while the nvTregs show enhanced loss of function and increased decreased viability that worsen 17 with disease progression. Our goal is to identify the molecules or cells that induce these mechanisms of ALS 18 patient Treg inactivation, as ultimately these mechanisms could be therapeutically inactivated to restore ALS 19 patient Treg function and induce slowing of the disease. Our approach to this goal is described in three aims: 20 AIM 1. ELUCIDATE THE MECHANISMS OF mTREG DYSFUNCTION IN ALS. Our data indicates that 21 ALS-mTregs have reduced frequency in early stages of the disease, and are less proliferative and more prone 22 to lose FoxP3 expression (stability) in vitro. In this aim we will identify the cells and molecules that function in 23 early disease to inhibit mTreg growth and/or lineage stability. 24 AIM 2. DETERMINE THE MECHANISM OF nvTREG DYSFUNCTION IN ALS DISEASE 25 PROGRESSION. ALS nvTregs show increasingly poor suppressive activity as the disease progresses. They 26 also exhibit reduced viability, increased TNFa expression, and a unique gene profile in advanced disease. Here 27 we will explore ALS-nvTreg gene expression and how other cell lineages target and inactivate ALS-nvTregs. 28 AIM 3. EXAMINE HOW LOW-DOSE IL-2 AFFECTS Treg FUNCTION IN ALS PATIENTS. We will use 29 our human Treg expertise to determine if low-dose IL-2 augments Treg function in ALS patients that are being 30 treated under an EAP by our collaborators at the Mass General and the Sean Healey and AMG Center for ALS.