Investigation of the role of STING in the loss of anti-inflammatory function in LAP-deficient macrophages in the context of efferocytosis

Author(s)

Daniel Leonardo Alzamora Terrel

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2022-06-28

Examining board members

Larissa Dias da Cunha; José Carlos Farias Alves Filho; Alessandra D'Almeida Filardy

• Advisor: Larissa Dias da Cunha

Abstract

Defects in the recognition or degradation of dying and dead cells are associated with the development of autoimmune syndromes in murine models, potentially related to the accumulation of cellular debris. In this work, we demonstrate that aged animals with a deficiency in RUBCN (Rubcn-/-) and ATG5 (Atg5f/f LysM-Cre+), components of one of the non-canonical autophagy pathways (LAP), develop autoimmune phenotypes without severe manifestations of autoimmune disease. In this context, we investigated the contribution of the DNA sensor STING in the development of autoimmune phenotypes in LAP-deficient aged animals. STING is not essential for producing autoantibodies observed in LAP-deficient animals, but STING deletion reduced the deposition of immune complexes in the glomeruli, which suggests that STING activation in the absence of RUBCN (and possibly LAP) may contribute to local inflammation and kidney damage associated with autoimmune processes. Mechanistically, we investigated whether STING can regulate the anti-inflammatory polarization in LAP-deficient macrophages during efferocytosis. We confirm that primary bone marrow-derived macrophages (BMDM) with LAP defects exhibit a reduction in the expression of markers of anti-inflammatory function (such as Mrc1, Col1a1, Mgl2, Arg1, Tgfb1) in response to apoptotic cells. We also observed a reduction in the expression of Il4ra, the IL-4/13 receptor subunit, in Rubcn-/- and Atg5f/f LysM-Cre+ macrophages, which suggests that LAP can regulate signaling that polarizes the anti-inflammatory function of macrophages. However, deficiency in STING did not affect the reduction of anti-inflammatory markers expression and Il4ra in the absence of LAP. BMDM with defects in LAP (Rubcn-/-) as well as defects for both pathways (Rubcn-/- Sting1-/-), showed reduced levels of IL-10 in comparison to wild type macrophages (Rubcn+/+). Our results confirm that the loss of the anti-inflammatory profile associated with efferocytosis in LAP-deficient macrophages is not caused by a direct effect of STING activation. (AU)

• FAPESP's process: 19/21465-8 - STING activation and regulation of macrophage polarization in LAP-deficient macrophages during efferocytosis
• Grantee: Daniel Leonardo Alzamora Terrel
• Support Opportunities: Scholarships in Brazil - Master