Immunoglobulins and Serotonin modulate human macrophage polarization

1 p. Annual Scientific Meeting of the European Society for Clinical Investigation Cluj-Napoca, Romania 27– 30 May 2015Peer reviewe

MMP-12, Secreted by Pro-Inflammatory Macrophages, Targets Endoglin in Human Macrophages and Endothelial Cells

Upon inflammation, monocyte-derived macrophages (MF) infiltrate blood vessels to regulate several processes involved in vascular pathophysiology. However, little is known about the mediators involved. Macrophage polarization is crucial for a fast and e cient initial response (GM-MF) and a good resolution (M-MF) of the inflammatory process. The functional activity of polarized MF is exerted mainly through their secretome, which can target other cell types, including endothelial cells. Endoglin (CD105) is a cell surface receptor expressed by endothelial cells and MF that is markedly upregulated in inflammation and critically involved in angiogenesis. In addition, a soluble form of endoglin with anti-angiogenic activity has been described in inflammation-associated pathologies. The aim of this work was to identify components of the MF secretome involved in the shedding of soluble endoglin. We find that the GM-MF secretome contains metalloprotease 12 (MMP-12), a GM-MF specific marker that may account for the anti-angiogenic activity of the GM-MF secretome. Cell surface endoglin is present in both GM-MF and M-MF, but soluble endoglin is only detected in GM-MF culture supernatants. Moreover, MMP-12 is responsible for the shedding of soluble endoglin in vitro and in vivo by targeting membrane-bound endoglin in both MF and endothelial cells. These data demonstrate a direct correlation between GM-MF polarization, MMP-12, and soluble endoglin expression and function. By targeting endothelial cells, MMP-12 may represent a novel mediator involved in vascular homeostasis.Ministerio de Ciencia, Innovación y Universidades of Spain (SAF2013-43421-R to C.B.; SAF2017-83785-R and SAF2014-23801 to A.L.C.)Consejo Superior de Investigaciones Cientificas (201920E022 to C.B.)Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER; ISCIII-CB06/07/0038 to C.B.)Czech Republic Specific University Research (SVV-260414 to P.N.)CIBERER is an initiative of the Instituto de Salud Carlos III (ISCIII) of Spain supported by FEDER fundsM.A. was funded with a fellowship from Ministerio de Ciencia e Innovación (BES-2008-003888)M.V. was supported by a short-term mobility fellowship from the European Erasmus Programm

Mice lacking endoglin in macrophages show an impaired immune response

24 p.-9 fig.-1 tab. Ojeda Fernández, Luisa et al.Endoglin is an auxiliary receptor for members of the TGF-β superfamily and plays an important role in the homeostasis of the vessel wall. Mutations in endoglin gene (ENG) or in the closely related TGF-β receptor type I ACVRL1/ALK1 are responsible for a rare dominant vascular dysplasia, the Hereditary Hemorrhagic Telangiectasia (HHT), or Rendu-OslerWeber syndrome. Endoglin is also expressed in human macrophages, but its role in macrophage function remains unknown. In this work, we show that endoglin expression is triggered during the monocyte-macrophage differentiation process, both in vitro and during the in vivo differentiation of blood monocytes recruited to foci of inflammation in wild-type C57BL/6 mice. To analyze the role of endoglin in macrophages in vivo, an endoglin myeloid lineage specific knock-out mouse line (Engfl/flLysMCre) was generated. These mice show a predisposition to develop spontaneous infections by opportunistic bacteria. Engfl/flLysMCre mice also display increased survival following LPS-induced peritonitis, suggesting a delayed immune response. Phagocytic activity is impaired in peritoneal macrophages, altering one of the main functions of macrophages which contributes to the initiation of the immune response. We also observed altered expression of TGF-β1 target genes in endoglin deficient peritoneal macrophages. Overall, the altered immune activity of endoglin deficient macrophages could help to explain the higher rate of infectious diseases seen in HHT1 patients.This work was funded by: Ministerio de Economía y Competitividad of Spain (SAF2011-23475 to LMB; SAF2013-43421-R and SAF2010- 19222 to CB.Peer reviewe

Immunomodulation of human macrophages and myeloid cells by 2-substituted (1-3)-β-D-glucan from P. parvulus 2.6

17 p.-3 fig.-glucans produced by eukaryotic cells and by microorganisms are known to modulate immune responses by affecting macrophage activation. Here, we have investigated the effect of purified 2-substituted (1–3)- -d-glucan, produced by either Pediococcus parvulus 2.6 or Lactococcus lactis NZ9000[pNGTF], on the effector functions of human PMA-differentiated THP-1 cells and M1 proinflammatory monocyte-derived macrophages. The results reveal that this kind of -D-glucan activates macrophages and has an anti-inflammatory effect.This work was supported by the Spanish Ministry of Education grants AGL2009-12998 and AGL2012-40084.Peer reviewe

Expression of endoglin isoforms in the myeloid lineage and their role during aging and macrophage polarization

20 p.-6 fig.-3 fig. supl.-2 tab. supl.Endoglin plays a crucial role in pathophysiological processes such as hereditary hemorrhagic telangiectasia (HHT), preeclampsia and cancer. Endoglin expression is upregulated during the monocyte-to-macrophage transition, but little is known about its regulation and function in these immune cells. Two different alternatively spliced isoforms of endoglin have been reported, L-endoglin and S-endoglin. Although L-endoglin is the predominant variant, here, we found that there was an increased expression of the S-endoglin isoform during senescence of the myeloid lineage in human and murine models. We performed a stable isotope labelling of amino acids in cell culture (SILAC) analysis of both L-endoglin and S-endoglin transfectants in the human promonocytic cell line U937. Analysis of differentially expressed protein clusters allowed the identification of cellular activities affected during aging. S-endoglin expression led to decreased cellular proliferation and a decreased survival response to granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced apoptosis, as well as increased oxidative stress. Gene expression and functional studies suggested that there was a non-redundant role for each endoglin isoform in monocyte biology. In addition, we found that S-endoglin impairs the monocytic differentiation into the pro-inflammatory M1 phenotype and contributes to the compromised status of macrophage functions during aging.This study was supported by grants from Ministerio de Economía y Competitividad of Spain [grant number SAF2010-19222 to C.B.]; and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) (to C.B.). CIBERER is an initiative of the Instituto de Salud Carlos III (ISCIII) of Spain supported by FEDER funds. M.A. was supported by a fellowship from Ministerio de Ciencia e Innovación [grant number BES-2008-003888].Peer reviewe

Serotonin drives the acquisition of a profibrotic and anti-inflammatory gene profile through the 5-HT7RPKA signaling axis

15 p.-6 fig.-1 tab.Peripheral serotonin (5-hydroxytryptamine, 5-HT) regulates cell growth and differentiation in numerous cell types through engagement of seven types of cell surface receptors (HTR1–7). Deregulated 5-HT/ HTR levels contribute to pathology in chronic inflammatory diseases, with macrophages being relevant targets for the physio-pathological effects of 5-HT. In fact, 5-HT skews human macrophage polarization through engagement of 5-HT2BR and 5-HT7R receptors. We now report that 5-HT primes macrophages for reduced pro-inflammatory cytokine production and IFN type I-mediated signaling, and promotes an anti-inflammatory and pro-fibrotic gene signature in human macrophages. The acquisition of the 5-HT-dependent gene profile primarily depends on the 5-HT7R receptor and 5-HT7R-initiated PKAdependent signaling. In line with the transcriptional results, 5-HT upregulates TGFβ1 production by human macrophages in an HTR7- and PKA-dependent manner, whereas the absence of Htr7 in vivo results in diminished macrophage infiltration and collagen deposition in a mouse model of skin fibrosis.Our results indicate that the anti-inflammatory and pro-fibrotic activity of 5-HT is primarily mediated through the 5-HT7R-PKA axis, and that 5-HT7R contributes to pathology in fibrotic diseases.This work was supported by grants from Ministerio de Economía y Competitividad (SAF2011-23801 and SAF2014-52423-R to MAV and ALC, and PI I12/439 to JLP), “Programa de Actividades de I + D” from the Comunidad de Madrid/FEDER (RAPHYME S2010/BMD-2350 to JLP and ALC), and RIER (Red de Investigación en Inflamación y Enfermedades Reumáticas, RD12/09 to ALC and JLP) from the Instituto de Salud Carlos III,Ministerio de Economía y Competitividad, Spain (co-financed by FEDER, European Union). MCE was supported by an FPI predoctoral fellowship (BES-2009-021465) from Ministerio de Economía e Innovación.Peer reviewe

Serotonin (5-HT) Shapes the Macrophage Gene Profile through the 5-HT2B –Dependent Activation of the Aryl Hydrocarbon Receptor

International audienceMacrophages can either promote or resolve inflammatory responses, and their polarization state is modulated by peripheral serotonin (5-hydroxytryptamine [5-HT]). In fact, pro- and anti-inflammatory macrophages differ in the expression of serotonin receptors, with 5-HT2B and 5-HT7 expression restricted to M-CSF-primed monocyte-derived macrophages (M-MØ). 5-HT7 drives the acquisition of profibrotic and anti-inflammatory functions in M-MØ, whereas 5-HT2B prevents the degeneration of spinal cord mononuclear phagocytes and modulates motility of murine microglial processes. Because 5-HT2B mediates clinically relevant 5-HT-related pathologies (valvular heart disease, pulmonary arterial hypertension) and is an off target of anesthetics, antiparkinsonian drugs, and selective serotonin reuptake inhibitors, we sought to determine the transcriptional consequences of 5-HT2B engagement in human macrophages, for which 5-HT2B signaling remains unknown. Assessment of the effects of specific agonists and antagonist revealed that 5-HT2B engagement modifies the cytokine and gene signature of anti-inflammatory M-MØ, upregulates the expression of aryl hydrocarbon receptor (AhR) target genes, and stimulates the transcriptional activation of AhR. Moreover, we found that 5-HT dose dependently upregulates the expression of AhR target genes in M-MØ and that the 5-HT-mediated activation of AhR is 5-HT2B dependent because it is abrogated by the 5-HT2B-specific antagonist SB204741. Altogether, our results demonstrate the existence of a functional 5-HT/5-HT2B/AhR axis in human macrophages and indicate that 5-HT potentiates the activity of a transcription factor (AhR) that regulates immune responses and the biological responses to xenobiotics

Intravenous immunoglobulin promotes antitumor responses by modulating macrophage polarization

et al.Intravenous Igs (IVIg) therapy is widely used as an immunomodulatory strategy in inflammatory pathologies and is suggested to promote cancer regression. Because progression of tumors depends on their ability to redirect the polarization state of tumorassociated macrophages (from M1/immunogenic/proinflammatory to M2/anti-inflammatory), we have evaluated whether IVIg limits tumor progression and dissemination through modulation of macrophage polarization. In vitro, IVIg inhibited proinflammatory cytokine production from M1 macrophages and induced a M2-To-M1 polarization switch on human and murine M2 macrophages. In vivo, IVIg modified the polarization of tumor-associated myeloid cells in a Fcεr1γ chain-dependent manner, modulated cytokine blood levels in tumor-bearing animals, and impaired tumor progression via FcγRIII (CD16), FcγRIV, and FcRγ engagement, the latter two effects being macrophage mediated. Therefore, IVIg immunomodulatory activity is dependent on the polarization state of the responding macrophages, and its ability to trigger a M2-To-M1 macrophage polarization switch might be therapeutically useful in cancer, in which proinflammatory or immunogenic functions should be promoted.This work was supported by grants from Ministerio de Economía y Competitividad (SAF2011-23801), Genoma España (Mecanismos moleculares en enfermedades inflamatorias crónicas y autoinmunes project), Instituto de Salud Carlos III (Red de Investigación en Enfermedades Reumáticas), and Comunidad Autónoma de Madrid/Fondo Europeo de Desarrollo Regional (Rheumatoid Arthritis: Physiopathology Mechanisms Program) (to A.L.C.), and Ministerio de Economía y Competitividad Grant SAF2010-15106 (to M.L.T.). M.d.l.C.-E. is supported by a Formación de Personal Investigador predoctoral fellowship (BES-2009-021465) from Ministerio de Economía y Competitividad.Peer Reviewe