Critical Role of Notch‐1 in Mechanistic Target of Rapamycin Hyperactivity and Vascular Inflammation in Patients With Takayasu Arteritis

Abstract

Objective Takayasu arteritis (TA) is a major type of large vessel vasculitis characterized by progressive inflammation in vascular layers. In our recent study we identified a central role of mechanistic target of rapamycin (mTOR) hyperactivity in proinflammatory T cell differentiation in TA. This study was undertaken to explore potential mechanisms underpinning T cell–intrinsic mTOR hyperactivity and vascular inflammation in TA, with a focus on Notch‐1. Methods Notch‐1 expression and activity was determined according to Notch‐1, activated Notch‐1, and HES‐1 levels. We detected mTOR activity with intracellular expression of phosphorylated ribosomal protein S6. Differentiation of proinflammatory T cells was analyzed by detecting Th1 and Th17 lineage‐determining transcription factors. The function of Notch‐1 was evaluated using γ‐secretase inhibitor DAPT and gene knockdown using a short hairpin RNA (shRNA) strategy. We performed our translational study using humanized NSG mouse chimeras in which human vasculitis was induced using immune cells from TA patients. Results CD4+ T cells from TA patients exerted Notch‐1high, leading to mTOR hyperactivity and spontaneous maldifferentiation of Th1 cells and Th17 cells. Blockade of Notch‐1 using DAPT and Notch‐1 shRNA efficiently abrogated mTOR complex 1 (mTORC1) activation and proinflammatory T cell differentiation. Mechanistically, Notch‐1 promoted mTOR expression, interacted with mTOR, and was associated with lysosomal localization of mTOR. Accordingly, systemic administration of DAPT and CD4+ T cell–specific gene knockdown of Notch‐1 could alleviate vascular inflammation in humanized TA chimeras. Conclusion Expression of Notch‐1 is elevated in CD4+ T cells from TA patients, resulting in mTORC1 hyperactivity and proinflammatory T cell differentiation. Targeting Notch‐1 is a promising therapeutic strategy for the clinical management of TA.

Vasculitogenic T Cells in Large Vessel Vasculitis

“…Similar to GCA, an increase in Th1 and Th17 cells has been reported in TAK ( 16 , 87 ). This increase may stem from overactivation of the NOTCH1-mTOR pathway ( 88 , 89 ) and/or an increase in the number of CD4 + IL-21-producing T cells ( 89 , 90 ). In parallel, a decrease in CD4 + Treg numbers has also been documented ( 91 ).…”

AMPK hyperactivity maintains the survival of vasculogenic T cells in patients with Takayasu's arteritis

“…Takayasu's arteritis (TAK) is a progressive autoimmune vasculitis that mainly affects the aorta and the major branches, with increasing morbidity and mortality (1)(2)(3)(4)(5). This disease is more common in females and can be seen in all ethnicities (1,(3)(4)(5).…”

“…Takayasu's arteritis (TAK) is a progressive autoimmune vasculitis that mainly affects the aorta and the major branches, with increasing morbidity and mortality (1)(2)(3)(4)(5). This disease is more common in females and can be seen in all ethnicities (1,(3)(4)(5). While imaging tools such as CTA, MRA and contrastenhanced ultrasonography are used for disease diagnosis and inflammation assessment of vascular layers, diagnoses are still frequently delayed, and the underlying pathogenesis of TAK remains largely undefined, resulting in limited treatment options in clinical practice (3)(4)(5)(6).…”

“…This disease is more common in females and can be seen in all ethnicities (1,(3)(4)(5). While imaging tools such as CTA, MRA and contrastenhanced ultrasonography are used for disease diagnosis and inflammation assessment of vascular layers, diagnoses are still frequently delayed, and the underlying pathogenesis of TAK remains largely undefined, resulting in limited treatment options in clinical practice (3)(4)(5)(6). In patients with TAK, adventitia of affected arteries is frequently infiltrated with immune cells, which drive vascular inflammation and subsequent organ damage (3,4,7).…”

“…While imaging tools such as CTA, MRA and contrastenhanced ultrasonography are used for disease diagnosis and inflammation assessment of vascular layers, diagnoses are still frequently delayed, and the underlying pathogenesis of TAK remains largely undefined, resulting in limited treatment options in clinical practice (3)(4)(5)(6). In patients with TAK, adventitia of affected arteries is frequently infiltrated with immune cells, which drive vascular inflammation and subsequent organ damage (3,4,7). Specifically, proinflammatory CD4 T cells, including T helper type 1 (Th1) and Th17 cells, are the dominant vasculogenic infiltrates in the vascular layers of TAK patients, assigning IFN-γ and IL-17 as critical cytokines involved in disease pathogenesis (3,4,7,8).…”