Mecanismes moleculars implicats en la interacció dels receptors cel·lulars herpes simplex entry mediator A (HveA) i receptor de complement 2 (CR2, CD21) amb els seus lligands

Consultable des del TDXTítol obtingut de la portada digitalitzadaL'estudi de la utilització del sistema immunològic de l'hoste pels virus com a patògens per al seu propi benefici fou el principal objectiu d'aquest treball. Concretament, en aquest treball de tesis es van analitzar dues espècies d'herpesvirus virulents en humans, l'Herpes Simplex Virus-1 (HSV-1) i l'Epstein Barr Virus (EBV). L'entrada d'ambdós virus a les cèl·lules és mediada per receptors del sistema immunològic. Es va estudiar la interacció dels respectius receptors cel·lulars, Herpes Virus Entry mediator A (HveA), i el receptor de complement 2 (CR2), amb les glicoproteïnes virals que s'hi uneixen, i amb llurs lligands naturals, els quals participen en la defensa de l'hoste. Es va caracteritzar la interacció dels receptors HveA i CR2 amb els seus lligands fent servir proteïnes recombinants o purificades de sèrum; en el cas de HveA ens vam centrar en la localització del lloc d'unió de cada lligand al receptor. En el cas de CR2, es va analitzar la cinètica d'unió dels seus lligands naturals. Per a ambdós receptors, es va analitzar si la unió de la proteïna viral al receptor podria interferir i/o modular-ne la unió dels seus lligands naturals. Els resultats es van analitzar dins del marc de la resposta immunològica de l'hoste mediada pel receptor cel·lular, i en relació al possible paper modificador d'aquesta resposta per part de la proteïna viral. Per a facilitar el nostre estudi sobre HveA, es van cercar nous lligands peptídics d'aquest receptor, utilitzant llibreries aleatòries de pèptids expressades en el fag M13. Es van aïllar dos pèptids, i es va estudiar la seva interacció amb el receptor i la seva capacitat d'inhibir l'entrada del virus a les cèl·lules, és a dir, com a possibles agents terapèutics.Our goal in the present work was to study the manipulation of the host immune system by an infecting virus to its own benefit. Specifically, we studied two herpes viruses; Herpes Simplex Virus-1 (HSV-1) and Epstein Barr Virus (EBV), which infect humans. Entry of both viruses into the cell is mediated by the interaction of a specific viral surface glycoprotein with two receptors that participate in the host immune response, the Herpes Virus Entry mediator A (HveA), and complement receptor 2 (CR2). We studied the interaction of these receptors with the viral glycoproteins as well as their host ligands. The latter play a role in the immune response of the host. We characterized these interactions by using recombinant as well as serum-purified proteins. Our study of HveA sought to localize the specific binding site of each ligand on the receptor, while that of CR2 consisted in the kinetic analysis of its interaction with its ligands. We also analyzed whether binding of the viral glycoprotein to each receptor would interfere or modulate its interaction with its host ligands. Our results were analyzed in the context of the role of these receptors in the host immune response, and specifically whether the viral proteins studied undermined the host's ability to defend itself from infection. To study the relationship between HveA, its natural ligands, and the viral proteins involved in HSV entry, we also screened two phage-displayed combinatorial peptide libraries for peptide ligands of a recombinant form of HveA. We isolated two peptides, and studied their interaction with HveA as well as their ability to block HSV entry into HveA-bearing cells

CD5L promotes M2 macrophage polarization through autophagy-mediated upregulation of ID3

CD5L (CD5 molecule-like) is a secreted glycoprotein that controls key mechanisms in inflammatory responses, with involvement in processes such as infection, atherosclerosis, and cancer. In macrophages, CD5L promotes an anti-inflammatory cytokine profile in response to TLR activation. In the present study, we questioned whether CD5L is able to influence human macrophage plasticity, and drive its polarization toward any specific phenotype. We compared CD5L-induced phenotypic and functional changes to those caused by IFN/LPS, IL4, and IL10 in human monocytes. Phenotypic markers were quantified by RT-qPCR and flow cytometry, and a mathematical algorithm was built for their analysis. Moreover, we compared ROS production, phagocytic capacity, and inflammatory responses to LPS. CD5L drove cells toward a polarization similar to that induced by IL10. Furthermore, IL10- and CD5L-treated macrophages showed increased LC3-II content and colocalization with acidic compartments, thereby pointing to the enhancement of autophagy-dependent processes. Accordingly, siRNA targeting ATG7 in THP1 cells blocked CD5L-induced CD163 and Mer tyrosine kinase mRNA and efferocytosis. In these cells, gene expression profiling and validation indicated the upregulation of the transcription factor ID3 by CD5L through ATG7. In agreement, ID3 silencing reversed polarization by CD5L. Our data point to a significant contribution of CD5L-mediated autophagy to the induction of ID3 and provide the first evidence that CD5L drives macrophage polarization.Peer ReviewedPostprint (published version

Reduced plasma extracellular vesicle CD5L content in patients with acute-on-chronic liver failure: interplay with specialized pro-resolving lipid mediators.

Acute-on chronic liver failure (ACLF) is a syndrome that develops in patients with acutely decompensated cirrhosis (AD). It is characterized by a systemic hyperinflammatory state, leading to multiple organ failure. Our objective was to analyze macrophage anti-inflammatory protein CD5L in plasma extracellular vesicles (EVs) and assess its as yet unknown relationship with lipid mediators in ACLF. With this aim, EVs were purified by size exclusion chromatography from the plasma of healthy subjects (HS) (n=6) and patients with compensated cirrhosis (CC) (n=6), AD (n=11) and ACLF (n=11), which were defined as positive for CD9, CD5L and CD63 and their size, number, morphology and lipid mediator content were characterized by NTA, EM, and LC-MS/MS, respectively. Additionally, plasma CD5L was quantified by ELISA in 10 HS, 20 CC and 149 AD patients (69 ACLF). Moreover, macrophage CD5L expression and the biosynthesis of specialized lipid mediators (SPMs) were characterized in vitro in primary cells. Our results indicate that circulating EVs were significantly suppressed in cirrhosis, regardless of severity, and showed considerable alterations in CD5L and lipid mediator content as the disease progressed. In AD, levels of EV CD5L correlated best with those of the SPM RvE1. Analysis of total plasma supported these data and showed that, in ACLF, low CD5L levels were associated with circulatory (p<0.001), brain (p<0.008) and respiratory (p<0.05) failure (Mann-Whitney test). Functional studies in macrophages indicated a positive feedback loop between CD5L and RvE1 biosynthesis. In summary, we have determined a significant alteration of circulating EV contents in ACLF, with a loss of anti-inflammatory and pro-resolving molecules involved in the control of acute inflammation in this condition

Circulating soluble CD36 is similar in type 1 and type 2 diabetes mellitus versus non-diabetic subjects

The aim of this study was to determine whether plasma concentrations of sCD36 (soluble CD36) are associated with the presence of type 1 or type 2 diabetes. Plasma levels of sCD36 were analysed in 1023 subjects (225 type 1 diabetes (T1D) patients, 276 type 2 diabetes (T2D) patients, and 522 non-diabetic control subjects) using an enzyme-linked immunosorbent assay (ELISA). Multinomial and logistic regression models were performed to evaluate associations with sCD36 and its association with diabetes types. There were no significant differences in sCD36 (p = 0.144) among study groups, neither in head-to-head comparisons: non-diabetic versus T1D subjects (p = 0.180), non-diabetic versus T2D subjects (p = 0.583), and T1D versus T2D patients (p = 0.151). In the multinomial model, lower sCD36 concentrations were associated with older age (p < 0.001), tobacco exposure (p = 0.006), T2D (p = 0.020), and a higher-platelets count (p = 0.004). However, in logistic regression models of diabetes, sCD36 showed only a weak association with T2D. The current findings show a weak association of circulating sCD36 with type 2 diabetes and no association with T1D

Role of the Scavenger Receptor CD36 in Accelerated Diabetic Atherosclerosis

Diabetes mellitus entails increased atherosclerotic burden and medial arterial calcification, but the precise mechanisms are not fully elucidated. We aimed to investigate the implication of CD36 in inflammation and calcification processes orchestrated by vascular smooth muscle cells (VSMCs) under hyperglycemic and atherogenic conditions. We examined the expression of CD36, pro-inflammatory cytokines, endoplasmic reticulum (ER) stress markers, and mineralization-regulating enzymes by RT-PCR in human VSMCs, cultured in a medium containing normal (5 mM) or high glucose (22 mM) for 72 h with or without oxidized low-density lipoprotein (oxLDL) (24 h). The uptake of 1,1'-dioctadecyl-3,3,3',3-tetramethylindocarbocyanine perchlorate-fluorescently (DiI) labeled oxLDL was quantified by flow cytometry and fluorimetry and calcification assays were performed in VSMC cultured in osteogenic medium and stained by alizarin red. We observed induction in the expression of CD36, cytokines, calcification markers, and ER stress markers under high glucose that was exacerbated by oxLDL. These results were confirmed in carotid plaques from subjects with diabetes versus non-diabetic subjects. Accordingly, the uptake of DiI-labeled oxLDL was increased after exposure to high glucose. The silencing of CD36 reduced the induction of CD36 and the expression of calcification enzymes and mineralization of VSMC. Our results indicate that CD36 signaling is partially involved in hyperglycemia and oxLDL-induced vascular calcification in diabetes

Identification of the most vulnerable populations in the psychosocial sphere: a cross-sectional study conducted in Catalonia during the strict lockdown imposed against the COVID-19 pandemic.

Design and objectives A cross-sectional study to evaluate the impact of COVID-19 on the psychosocial sphere in both the general population and healthcare workers (HCWs). Methods The study was conducted in Catalonia (Spain) during the first wave of the COVID-19 pandemic when strict lockdown was in force. The study population included all people aged over 16 years who consented to participate in the study and completed the survey, in this case a 74-question questionnaire shared via social media using snowball sampling. A total of 56 656 completed survey questionnaires were obtained between 3 and 19 April 2020. The primary and secondary outcome measures included descriptive statistics for the non-psychological questions and the psychological impact of the pandemic, such as depression, anxiety, stress and post-traumatic stress disorder question scores. Results A n early and markedly negative impact on family finances, fear of working with COVID-19 patients and ethical issues related to COVID-19 care among HCWs was observed. A total of seven target groups at higher risk of impaired mental health and which may therefore benefit from an intervention were identified, namely women, subjects aged less than 42 years, people with a care burden, socioeconomically deprived groups, people with unskilled or unqualified jobs, patients with COVID-19 and HCWs working with patients with COVID-19. Conclusions Active implementation of specific strategies to increase resilience and to prepare an adequate organisational response should be encouraged for the seven groups identified as high risk and susceptible to benefit from an intervention

Nanosized UCMSC-derived extracellular vesicles but not conditioned medium exclusively inhibit the inflammatory response of stimulated T cells: implications for nanomedicine

Altres ajuts: La Marató TV3 (201502 i 201516). This work has been developed in the context of AdvanceCat with the support of ACCIÓ (Catalonia Trade & Investment; Generalitat de Catalunya) under the Catalonian ERDF operational program (European Regional Development Fund) 2014-2020. FEB is sponsored by the "Researchers Stabilization Program" from the Spanish "Sistema Nacional de Salud" (SNS-ISCIII) and "Direcció d'Estratègia i Coordinació" Catalan Health Department (CES07/015).Undesired immune responses have drastically hampered outcomes after allogeneic organ transplantation and cell therapy, and also lead to inflammatory diseases and autoimmunity. Umbilical cord mesenchymal stem cells (UCMSCs) have powerful regenerative and immunomodulatory potential, and their secreted extracellular vesicles (EVs) are envisaged as a promising natural source of nanoparticles to increase outcomes in organ transplantation and control inflammatory diseases. However, poor EV preparations containing highly-abundant soluble proteins may mask genuine vesicular-associated functions and provide misleading data. Here, we used Size-Exclusion Chromatography (SEC) to successfully isolate EVs from UCMSCs-conditioned medium. These vesicles were defined as positive for CD9, CD63, CD73 and CD90, and their size and morphology characterized by NTA and cryo-EM. Their immunomodulatory potential was determined in polyclonal T cell proliferation assays, analysis of cytokine profiles and in the skewing of monocyte polarization. In sharp contrast to the non-EV containing fractions, to the complete conditioned medium and to ultracentrifuged pellet, SEC-purified EVs from UCMSCs inhibited T cell proliferation, resembling the effect of parental UCMSCs. Moreover, while SEC-EVs did not induce cytokine response, the non-EV fractions, conditioned medium and ultracentrifuged pellet promoted the secretion of pro-inflammatory cytokines by polyclonally stimulated T cells and supported Th17 polarization. In contrast, EVs did not induce monocyte polarization, but the non-EV fraction induced CD163 and CD206 expression and TNF-α production in monocytes. These findings increase the growing evidence confirming that EVs are an active component of MSC's paracrine immunosuppressive function and affirm their potential for therapeutics in nanomedicine. In addition, our results highlight the importance of well-purified and defined preparations of MSC-derived EVs to achieve the immunosuppressive effect

Low doses of LPS exacerbate the inflammatory response and trigger death on TLR3-primed human monocytes

TLR sensing of pathogens triggers monocyte activation to initiate the host innate immune response to infection. Monocytes can dynamically adapt to different TLR agonists inducing different patterns of inflammatory response, and the sequence of exposure to TLRs can dramatically modulate cell activation. Understanding the interactions between TLR signalling that lead to synergy, priming and tolerance to TLR agonists may help explain how prior infections and inflammatory conditioning can regulate the innate immune response to subsequent infections. Our goal was to investigate the role of MyD88-independent/dependent TLR priming on modulating the monocyte response to LPS exposure. We stimulated human blood monocytes with agonists for TLR4 (LPS), TLR3 (poly(I:C)) and TLR7/8 (R848) and subsequently challenged them to low doses of endotoxin. The different TLR agonists promoted distinct inflammatory signatures in monocytes. Upon subsequent LPS challenge, LPS- and R848-primed monocytes did not enhance the previous response, whereas poly(I:C)-primed monocytes exhibited a significant inflammatory response concomitant with a sharp reduction on cell viability. Our results show that TLR3-primed monocytes are prompted to cell death by apoptosis in the presence of low endotoxin levels, concurrent with the production of high levels of TNFα and IL6. Of note, blocking of TNFR I/II in those monocytes did reduce TNFα production but did not abrogate cell death. Instead, direct signalling through TLR4 was responsible of such effect. Collectively, our study provides new insights on the effects of cross-priming and synergism between TLR3 and TLR4, identifying the selective induction of apoptosis as a strategy for TLR-mediated host innate response

Mycobacterium manresensis induces trained immunity in vitro

The COVID-19 pandemic posed a global health crisis, with new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants weakening vaccine-driven protection. Trained immunity could help tackle COVID-19 disease. Our objective was to analyze whether heat-killed Mycobacterium manresensis (hkMm), an environmental mycobacterium, induces trained immunity and confers protection against SARS-CoV-2 infection. To this end, THP-1 cells and primary monocytes were trained with hkMm. The increased secretion of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1β, and IL-10, metabolic activity, and changes in epigenetic marks suggested hkMm-induced trained immunity in vitro. Healthcare workers at risk of SARS-CoV-2 infection were enrolled into the MANRECOVID19 clinical trial (NCT04452773) and were administered Nyaditum resae (NR, containing hkMm) or placebo. No significant differences in monocyte inflammatory responses or the incidence of SARS-CoV-2 infection were found between the groups, although NR modified the profile of circulating immune cell populations. Our results show that M. manresensis induces trained immunity in vitro but not in vivo when orally administered as NR daily for 14 days. Biological sciences; Molecular biology; Immunology; Microbiolog