Lipoxin A4 impairment of apoptotic signaling in macrophages: Implication of the PI3K/Akt and the ERK/Nrf-2 defense pathways

El pdf del artículo es la versión pre-print.Lipoxin A4 (LXA4) is an endogenous lipid mediator that requires transcellular metabolic traffic for its synthesis. The targets of LXA4 on neutrophils are well described, contributing to attenuation of inflammation. However, effects of lipoxins on macrophage are less known, particularly the action of LXA4 on the regulation of apoptosis of these cells. Our data show that pretreatment of human or murine macrophages with LXA4 at the concentrations prevailing in the course of resolution of inflammation (nanomolar range) significantly inhibits the apoptosis induced by staurosporine, etoposide and S-nitrosoglutathione or by more pathophysiological stimuli, such as LPS/IFNγ challenge. The release of mitochondrial mediators of apoptosis and the activation of caspases was abrogated in the presence of LXA4. In addition to this, the synthesis of reactive oxygen species induced by staurosporine was attenuated and antiapoptotic proteins of the Bcl-2 family accumulated in the presence of lipoxin. Analysis of the targets of LXA4 identified an early activation of the PI3K/Akt and ERK/Nrf-2 pathways, which was required for the observation of the antiapoptotic effects of LXA4. These data suggest that the LXA 4, released after the recruitment of neutrophils to sites of inflammation, exerts a protective effect on macrophage viability that might contribute to a better resolution of inflammation. © 2010 Macmillan Publishers Limited All rights reserved.PP was supported by a fellowship from Ministerio de Ciencia e Innovación (MICINN; Spain). This work was supported by grant BFU2008-02161 from MICINN, S-BIO-0283/2006 from Comunidad de Madrid and FIS-RECAVA RD06/0014/0025. RECAVA and Ciberehd are funded by the Instituto de Salud Carlos III.Peer Reviewe

ILK mediates LPS-induced vascular adhesion receptor expression and subsequent leucocyte trans-endothelial migration†

Aims The inflammatory response to injurious agents is tightly regulated to avoid adverse consequences of inappropriate leucocyte accumulation or failed resolution. Lipopolysaccharide (LPS)-activated endothelium recruits leucocytes to the inflamed tissue through controlled expression of membrane-associated adhesion molecules. LPS responses in macrophages are known to be regulated by integrin-linked kinase (ILK); in this study, we investigated the role of ILK in the regulation of the LPS-elicited inflammatory response in endothelium. Methods and results This study was performed on immortalized mouse endothelial cells (EC) isolated from lung and coronary vasculature. Cells were thoroughly characterized and the role of ILK in the regulation of the LPS response was investigated by suppressing ILK expression using siRNA and shRNA technologies. Phenotypic and functional analyses confirmed that the immortalized cells behaved as true EC. LPS induced the expression of the inflammatory genes E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). ILK knockdown impaired LPS-mediated endothelial activation by preventing the induction of ICAM-1 and VCAM-1. Blockade of the LPS-induced response inhibited the inflammatory-related processes of firm adhesion and trans-endothelial migration of leucocytes. Conclusion ILK is involved in the expression of cell adhesion molecules by EC activated with the inflammatory stimulus LPS. This reduced expression modulates leucocyte adhesion to the endothelium and the extravasation process. This finding suggests ILK as a potential anti-inflammatory target for the development of vascular-specific treatments for inflammation-related disease

Sustained release of prostaglandin E2 in fibroblasts expressing ectopically cyclooxygenase 2 impairs P2Y-dependent Ca2+-mobilization

The nucleotide uridine trisphosphate (UTP) released to the extracellular milieu acts as a signaling molecule via activation of specific pyrimidine receptors (P2Y). P2Y receptors are G protein-coupled receptors expressed in many cell types. These receptors mediate several cell responses and they are involved in intracellular calcium mobilization. We investigated the role of the prostanoid PGE2in P2Y signaling in mouse embryonic fibroblasts (MEFs), since these cells are involved in different ontogenic and physiopathological processes, among them is tissue repair following proinflammatory activation. Interestingly, Ca2+-mobilization induced by UTP-dependent P2Y activation was reduced by PGE2when this prostanoid was produced by MEFs transfected with COX-2 or when PGE2was added exogenously to the culture medium. This Ca2+-mobilization was important for the activation of different metabolic pathways in fibroblasts. Moreover, inhibition of COX-2 with selective coxibs prevented UTP-dependent P2Y activation in these cells. The inhibition of P2Y responses by PGE2involves the activation of PKCs and PKD, a response that can be suppressed after pharmacological inhibition of these protein kinases. In addition to this, PGE2reduces the fibroblast migration induced by P2Y-agonists such as UTP. Taken together, these data demonstrate that PGE2is involved in the regulation of P2Y signaling in these cells.This work was supported by Grants BFU2011-24760 and BFU2011-24743 from MINECO, S2010/BMD-2378 from Comunidad de Madrid, Red de Investigación Cardiovascular, RIC, RD12/0042/0019, and Fundación Marcelino Botín (to María Teresa Miras-Portugal). RIC and Ciberehd are funded by the Instituto de Salud Carlos III.Peer Reviewe

Mice Lacking Thyroid Hormone Receptor β Show Enhanced Apoptosis and Delayed Liver Commitment for Proliferation after Partial Hepatectomy

This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: The role of thyroid hormones and their receptors (TR) during liver regeneration after partial hepatectomy (PH) was studied using genetic and pharmacologic approaches. Roles in liver regeneration have been suggested for T3, but there is no clear evidence distinguishing the contribution of increased amounts of T3 from the modulation by unoccupied TRs. [Methodology/Principal Findings]: Mice lacking TR alpha 1/TR beta or TR beta alone fully regenerated liver mass after PH, but showed delayed commitment to the initial round of hepatocyte proliferation and transient but intense apoptosis at 48h post-PH, affecting similar to 30% of the remaining hepatocytes. Pharmacologically induced hypothyroidism yielded similar results. Loss of TR activity was associated with enhanced nitrosative stress in the liver remnant, due to an increase in the activity of the nitric oxide synthase (NOS) 2 and 3, caused by a transient decrease in the concentration of asymmetric dimethylarginine (ADMA), a potent NOS inhibitor. This decrease in the ADMA levels was due to the presence of a higher activity of dimethylarginineaminohydrolase-1 (DDAH-1) in the regenerating liver of animals lacking TR alpha 1/TR beta or TR beta. DDAH-1 expression and activity was paralleled by the activity of FXR, a transcription factor involved in liver regeneration and up-regulated in the absence of TR. [Conclusions/Significance]: We report that TRs are not required for liver regeneration; however, hypothyroid mice and TR beta-or TR alpha 1/TR beta-deficient mice exhibit a delay in the restoration of liver mass, suggesting a specific role for TRb in liver regeneration. Altered regenerative responses are related with a delay in the expression of cyclins D1 and E, and the occurrence of liver apoptosis in the absence of activated TRb that can be prevented by administration of NOS inhibitors. Taken together, these results indicate that TRb contributes significantly to the rapid initial round of hepatocyte proliferation following PH, and improves the survival of the regenerating liver at later times.This work was supported by grants BFU2008-02161, BFU2007-62402, SAF2007-60511, and SAF2007-60551 from MICINN; S-BIO-0283/2006 from Comunidad de Madrid and FIS-RECAVA RD06/0014/0025 to L.B.; and PI05.0050, PI080070, and the Fundacion Mutua Madrileña to S.H. RECAVA and Ciberehd are funded by the Instituto de Salud Carlos III. R. L-F. is supported by a fellowship from Instituto de Salud Carlos III. The CNIC is supported by the Spanish Ministry of Science and Innovation and the Pro-CNIC Foundation.Peer reviewe

Crosstalk Between LXR and Caveolin-1 Signaling Supports Cholesterol Efflux and Anti-Inflammatory Pathways in Macrophages

© 2021 Ramírez, Torrecilla-Parra, Pardo-Marqués, de-Frutos, Pérez-García, Tabraue, de la Rosa, Martín-Rodriguez, Díaz-Sarmiento, Nuñez, Orizaola, Través, Camps, Boscá and Castrillo.Macrophages are immune cells that play crucial roles in host defense against pathogens by triggering their exceptional phagocytic and inflammatory functions. Macrophages that reside in healthy tissues also accomplish important tasks to preserve organ homeostasis, including lipid uptake/efflux or apoptotic-cell clearance. Both homeostatic and inflammatory functions of macrophages require the precise stability of lipid-rich microdomains located at the cell membrane for the initiation of downstream signaling cascades. Caveolin-1 (Cav-1) is the main protein responsible for the biogenesis of caveolae and plays an important role in vascular inflammation and atherosclerosis. The Liver X receptors (LXRs) are key transcription factors for cholesterol efflux and inflammatory gene responses in macrophages. Although the role of Cav-1 in cellular cholesterol homeostasis and vascular inflammation has been reported, the connection between LXR transcriptional activity and Cav-1 expression and function in macrophages has not been investigated. Here, using gain and loss of function approaches, we demonstrate that LXR-dependent transcriptional pathways modulate Cav-1 expression and compartmentation within the membrane during macrophage activation. As a result, Cav-1 participates in LXR-dependent cholesterol efflux and the control of inflammatory responses. Together, our data show modulation of the LXR-Cav-1 axis could be exploited to control exacerbated inflammation and cholesterol overload in the macrophage during the pathogenesis of lipid and immune disorders, such as atherosclerosis.We thank MINECO FPI predoctoral fellowship granted to MCO (BES-2015-075339). Experimental work was supported by grants from Ministerio de Ciencia, Investigación y Universidades, y Fondo Europeo de Desarrollo Regional (FEDER) Grant REF: PID2019-104284RB-I00/AEI/10.13039/501100011033 (to AC) and support from Networks of Excellence from MINECO (Nuclear Receptors in Cancer, Metabolism and Inflammation [NuRCaMeIn] SAF2017-90604-REDT to AC. Ministerio de Economía, Industria y Competitividad, Ministerio de Ciencia, Investigación y Universidades, and Agencia Estatal de Investigación (SAF2017-82436-R, RTC2017-6283-1), Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CB16/11/00222), Consorcio de Investigación en Red de la Comunidad de Madrid, S2017/BMD-3686 and Fondo Europeo de Desarrollo Regional (to LB). Ministerio de Ciencia, Investigación y Universidades, and Agencia Estatal de Investigación Proyectos de I+D+i Retos Investigación 2018 (RTI2018-095061-B-I00); TALENTO Grant from Madrid Government, Spain (2017-T1/BMD-5333); Consejería de Ciencia, Universidades e Innovación Comunidad de Madrid, Spain (PEJD-2018-POST/BMD-8900 and PEDJ-2018-AI/BDM-9724) to CMR

Macrophages, Inflammation, and Tumor Suppressors: ARF, a New Player in the Game

The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed

Tumor suppressor ARF: The new player of innate immunity.

ARF (alternative reading frame) is one of the most important tumor regulator playing critical roles in controlling tumor initiation and progression. Recently, we have demonstrated a novel and unexpected role for ARF as modulator of inflammatory responses.S

Assessment of a dual regulatory role for NO in liver regeneration after partial hepatectomy: protection against apoptosis and retardation of hepatocyte proliferation

17 pages, 6 figures.-- et al.The role of hepatic nitric oxide (NO) in liver regeneration after partial hepatectomy (PH) was studied in animals carrying a nitric oxide synthase-2 transgene under the control of the phospho(enol)pyruvate carboxykinase promoter. These mice expressed NOS-2 in liver cells under fasting conditions. Liver mass recovery and molecular parameters related to cell proliferation were determined after PH. Preexisting hepatic NO synthesis, as well as NO delivery by NO-donors, impaired early signaling (for example, attenuated NF-kappaB activation and TNF-alpha and IL-6 release). The regenerative process was also impaired as a result of an insufficient proliferative response, but mouse survival after surgery was not compromised. However, NO exerted a protective role against apoptosis in transgenic hepatectomized mice. Local production of NO in liver cells, achieved by hydrodynamic-based transfection with a NOS-2-encoding plasmid, also resulted in delayed liver recovery after PH and also protected against Fas-mediated apoptosis. These data show that sustained presence of NO after PH exerts a dual role: attenuating liver regeneration while efficiently protecting against liver apoptosis.S.H. was supported by FIS. M.Z. and P.G.T. were supported by fellowships from the Comunidad de Madrid and the Ministerio de Ciencia y Tecnología, respectively. This work was supported by grants SAF2002-000783 and 08.3/0010/00-0008/01 from Ministerio de Ciencia y Tecnología, RECAVA and Comunidad de Madrid, respectively. S.H. was supported by FIS.Peer reviewe