Browsing by Author "Murgas, Paola"

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    Interferon-gamma ameliorates experimental autoimmune encephalomyelitis by inducing homeostatic adaptation of microglia
    (2023) Tichauer, Juan E.; Arellano, Gabriel; Acuna, Eric; Gonzalez, Luis F.; Kannaiyan, Nirmal R.; Murgas, Paola; Panadero-Medianero, Concepcion; Ibanez-Vega, Jorge; Burgos, Paula I.; Loda, Eileah; Miller, Stephen D.; Rossner, Moritz J.; Gebicke-Haerter, Peter J.; Naves, Rodrigo
    Compelling evidence has shown that interferon (IFN)-gamma has dual effects in multiple sclerosis and in its animal model of experimental autoimmune encephalomyelitis (EAE), with results supporting both a pathogenic and beneficial function. However, the mechanisms whereby IFN-gamma may promote neuroprotection in EAE and its effects on central nervous system (CNS)-resident cells have remained an enigma for more than 30 years. In this study, the impact of IFN-gamma at the peak of EAE, its effects on CNS infiltrating myeloid cells (MC) and microglia (MG), and the underlying cellular and molecular mechanisms were investigated. IFN-gamma administration resulted in disease amelioration and attenuation of neuroinflammation associated with significantly lower frequencies of CNS CD11b(+) myeloid cells and less infiltration of inflammatory cells and demyelination. A significant reduction in activated MG and enhanced resting MG was determined by flow cytometry and immunohistrochemistry. Primary MC/MG cultures obtained from the spinal cord of IFN-gamma-treated EAE mice that were ex vivo re-stimulated with a low dose (1 ng/ml) of IFN-gamma and neuroantigen, promoted a significantly higher induction of CD4(+) regulatory T (Treg) cells associated with increased transforming growth factor (TGF)-beta secretion. Additionally, IFN-gamma-treated primary MC/MG cultures produced significantly lower nitrite in response to LPS challenge than control MC/MG. IFN-gamma-treated EAE mice had a significantly higher frequency of CX3CR1(high) MC/MG and expressed lower levels of program death ligand 1 (PD-L1) than PBS-treated mice. Most CX3CR1(high)PD-L1(low)CD11b(+)Ly6G(-) cells expressed MG markers (Tmem119, Sall2, and P2ry12), indicating that they represented an enriched MG subset (CX3CR1(high)PD-L1(low) MG). Amelioration of clinical symptoms and induction of CX3CR1(high)PD-L1(low) MG by IFN-gamma were dependent on STAT-1. RNA-seq analyses revealed that in vivo treatment with IFN-gamma promoted the induction of homeostatic CX3CR1(high)PD-L1(low) MG, upregulating the expression of genes associated with tolerogenic and anti-inflammatory roles and down-regulating pro-inflammatory genes. These analyses highlight the master role that IFN-gamma plays in regulating microglial activity and provide new insights into the cellular and molecular mechanisms involved in the therapeutic activity of IFN-gamma in EAE.
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    Loss of stimulator of interferon genes (STING) promotes accumulation of cholesterol and triglycerides throughout life in mice
    (2025) Riquelme, Ian; Carrillanca, Daniela; Sánchez-Pérez, Camila; Monterroza, Andrea; Hernández-Rojas, Bairon; Riadi, Gonzalo; Cancino Lobos, Gonzalo Ignacio; Murgas, Paola
    Abstract Background The Stimulator of Interferon Genes (STING) pathway is pivotal in innate immunity, facilitating the detection of cytosolic DNA and initiating type I interferon-dependent responses. In addition to its immunological roles, STING has been increasingly associated with metabolic regulation, since research indicates that its inhibition can diminish inflammation, lipid accumulation, and tissue damage in obesity and other metabolic disorders. The findings have prompted the suggestion of STING inhibition as a viable treatment approach for metabolic illness. Nonetheless, the physiological function of STING in lipid homeostasis under normal settings remains largely unexplored, as does the impact of its absence on metabolism throughout various life stages in the absence of disease. This information deficit is crucial, particularly in light of the increasing interest in the long-term pharmacological suppression of STING. Results To examine the function of STING in lipid metabolism during physiological, non-pathological conditions throughout the lifespan, we assessed WT and STINGKO mice at various ages and discovered that STING deficiency results in a consistent increase in body weight, independent of alterations in locomotor activity or food consumption. STINGKO mice exhibited markedly increased circulation levels of triglycerides and total cholesterol. Histological and morphological analysis demonstrated augmented fat accumulation in adipose and hepatic tissues, despite the lack of nutritional or genetic metabolic stress. These findings indicate a crucial function for STING in the control of lipid homeostasis across the lifespan. Conclusions In contrast to earlier research conducted under pathological conditions, our findings indicate that the total absence of STING expression in healthy contexts leads to heightened lipid accumulation in tissues and blood. These findings underscore an unforeseen function of STING as a modulator of lipid metabolism in the context of longevity. They caution against the prolonged use of STING inhibitors, as chronic STING suppression may lead to detrimental metabolic effects. This study offers new insights into the non-immune roles of STING, indicating its significance in preserving metabolic equilibrium throughout the lifetime.
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    Maintenance of chronicity signatures in fibroblasts isolated from recessive dystrophic epidermolysis bullosa chronic wound dressings under culture conditions
    (2023) De Gregorio, Cristian; Catalán, Evelyng; Garrido, Gabriel; Morandé, Pilar; Bennett, Jimena C.; Muñoz, Catalina; Cofré, Glenda; Huang, Ya-Lin; Cuadra, Bárbara; Murgas, Paola; Calvo Bascuñan, Margarita; Altermatt Couratier, Fernando René; Yubero, María J.; Palisson, Francis; South, Andrew P.; Ezquer, Marcelo; Fuentes, Ignacia
    Background Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a rare inherited skin disease caused by variants in the COL7A1 gene, coding for type VII collagen (C7), an important component of anchoring fibrils in the basement membrane of the epidermis. RDEB patients suffer from skin fragility starting with blister formation and evolving into chronic wounds, inflammation and skin fibrosis, with a high risk of developing aggressive skin carcinomas. Restricted therapeutic options are limited by the lack of in vitro models of defective wound healing in RDEB patients. Results In order to explore a more efficient, non-invasive in vitro model for RDEB studies, we obtained patient fibroblasts derived from discarded dressings) and examined their phenotypic features compared with fibroblasts derived from non-injured skin of RDEB and healthy-donor skin biopsies. Our results demonstrate that fibroblasts derived from RDEB chronic wounds (RDEB-CW) displayed characteristics of senescent cells, increased myofibroblast differentiation, and augmented levels of TGF-β1 signaling components compared to fibroblasts derived from RDEB acute wounds and unaffected RDEB skin as well as skin from healthy-donors. Furthermore, RDEB-CW fibroblasts exhibited an increased pattern of inflammatory cytokine secretion (IL-1β and IL-6) when compared with RDEB and control fibroblasts. Interestingly, these aberrant patterns were found specifically in RDEB-CW fibroblasts independent of the culturing method, since fibroblasts obtained from dressing of acute wounds displayed a phenotype more similar to fibroblasts obtained from RDEB normal skin biopsies. Conclusions Our results show that in vitro cultured RDEB-CW fibroblasts maintain distinctive cellular and molecular characteristics resembling the inflammatory and fibrotic microenvironment observed in RDEB patients’ chronic wounds. This work describes a novel, non-invasive and painless strategy to obtain human fibroblasts chronically subjected to an inflammatory and fibrotic environment, supporting their use as an accessible model for in vitro studies of RDEB wound healing pathogenesis. As such, this approach is well suited to testing new therapeutic strategies under controlled laboratory conditions.