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Principal Investigator: Andrei Ivanovich Ivanov
Organization: CLEVELAND CLINIC LERNER COM-CWRU
Fiscal Year: 2024
Award: $604,875
Funding agency: National Institute of Diabetes and Digestive and Kidney Diseases
ABSTRACT
Over their disease course more than half of Crohn’s disease (CD) patients develop fibrosis-induced intestinal
obstruction and ultimately require surgery. No specific anti-fibrotic therapies are available. Despite advances
of anti-inflammatory therapies the incidence of strictures remains high, suggesting that inflammation-
independent mechanisms are crucial in the progression of the disease. The main effector cell mediating fibrosis
is the myofibroblast that is activated by multiple pro-fibrotic growth factors, such as transforming growth factor
(TGF)-1. Such activation results in accelerated secretion of extracellular matrix (ECM) and remodeling of the
actomyosin cytoskeleton. Septins are understudied cytoskeletal proteins that regulate secretory and actomyosin-
dependent cellular functions. No data on the roles and regulation of the septin cytoskeleton in intestinal
fibrosis exists. Our preliminary data shows a high gene expression of septins 2, 6, 7, 8, 9, 10, 11 in human
intestinal tissues with septin 7 as the most predominant isoform, which is upregulated in CD. Pharmacologic or
genetic disruption of the septin cytoskeleton inhibited TGF-β1-dependent increase in ECM production (Collagen
I & fibronectin) and migration in immortalized and primary human myo/fibroblasts. Preliminary evidence suggests
this is post-transcriptionally regulated. Septin modulation improved experimental murine fibrosis. We hence
propose to investigate the hypothesis that remodeling of the septin cytoskeleton is a driver of intestinal
fibrosis and targeting the septin cytoskeleton is a novel approach to therapy of fibrostenosing Crohn’s
disease. This hypothesis will be tested by three specific aims: AIM1. Characterization of alterations in septin
expression and distribution in tissue samples of IBD patients. This includes development of a high-resolution
map of septin expression profiles in human intestinal tissues and primary human intestinal myofibroblasts,
including generation of the first full thickness single cell RNA sequencing gut atlas for stricturing CD and controls.
AIM2. Investigation of the roles and mechanisms of septin dependent regulation of pro-fibrotic myofibroblast
activation. We will test if septin disruption or overexpression modulates TGF-β1-signaling, intracellular vesicular
trafficking or the translatome and post-transcriptionally regulated networks using a loss-of-function and gain-of-
function approach. AIM3. Functional exploration if targeting septins ameliorates intestinal fibrosis in vivo. We will
modulate septins in vivo using a pharmacologic and genetic approach and induce experimental fibrosis in two
different animal models. We will temporally control the deletion of the central septin 7 prior to (prevention) and
after induction (reversal) of experimental intestinal fibrosis specifically in Col I positive cells. If successful, this
proposal will challenge the paradigm of purely immune-driven ECM deposition driving stricture
formation and provide proof-of-concept for a novel mechanism to prevent or treat stricture associated
intestinal obstruction in CD patients.
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