Adriana Ferreira Lopes Vilela

Background: Mineral deposition in the extracellular matrix (ECM) is a highly organized process initiated by matrix vesicles (MVs) released from mineralization-competent cells, such as osteoblasts. In bone pathologies, osteogenic inducers (ions, hormones, nanoparticles) are becoming increasingly vital for the repair of damaged tissue. Among these inductors, strontium ranelate (SR), first suggested for treating osteoporotic patients, stands out. The bioactive strontium ion (Sr2+) has a dual mechanism of action in bone homeostasis: it activates osteoblasts, promoting bone formation, and inhibits osteoclasts, limiting bone resorption. Recent research has focused on how Sr2+ influences osteoblast function, but its effects on the mineralization process have not been explored. For this study, we hypothesized that Sr2+ modulates mineralization-competent cells at two levels: (a) it activates the extracellular signal-regulated kinase 1/2 (Erk1/2) and cAMP response element-binding protein (CREB) osteogenic signaling pathways, increasing mineral towards in the ECM, and (b) it regulates MV release and function. Advanced lipidomic analysis examined how Sr2+ affects the MV lipid profile, which is pivotal for MV biogenesis and bone formation. Methods: We performed an MTT assay to assess the cytotoxicity of CaCl2 and SR. Alizarin Red and Von Kossa staining were used to track mineral deposition towards the ECM. We assessed the phosphorylation states of ERK and CREB by western blotting and the osteogenic-related gene levels by quantitative real-time PCR. Biophysical characterization of 17A11-derived MVs was performed by nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), and zeta potential. Mineral deposition and characterization were performed by turbidimetry and Fourier transform infrared spectroscopy (FTIR), respectively. MV activity was studied by alkaline phosphatase activity. We also performed a Western blot analysis to assess MV markers. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were applied to investigate changes in membrane fluidity and the vesicles’ conformation. We explored the changes in lipid profiles using state-of-the-art lipidomic analysis. Results: Our findings demonstrate that Sr2+ activates the Erk1/2 and CREB pathways, leading to a dose-dependent increase in ECM mineralization. Additionally, the viscoelastic properties of MVs from Sr2+-stimulated 17IIA11 cells, a preodontoblast progenitor cell line, were altered, as demonstrated by AFM and TEM, which we linked to modifications in their lipid composition, as revealed by the enrichment of ceramide (Cer) and sphingomyelin (SM), both of which play pivotal roles in bone development. Conclusions: Our study demonstrated that Sr2+ affects the initiation of the mineralization process by changing the release and lipid composition of MVs, and acts, in part, through Erk1/2 and CREB signaling pathways.

Lipidomics, a subfield of metabolomics, involves the comprehensive analysis of lipids within biological systems and has become a cornerstone of biomedical research, driven by recent technological advancements. Lipids are crucial biomolecules in cellular functions and have been increasingly recognized for their roles in physiological and pathological processes. This study focuses on innovative strategies for developing, validating, and applying comprehensive analytical methods for untargeted lipidomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in human plasma and extracellular vesicles (EVs). We describe improvements based on analytical validation parameters, including inter-day repeatability, limit of quantification, precision, accuracy, recovery, and matrix effects. Plasma samples were used as a proof-of-concept study, and the method was ultimately applied to human macrophage-derived EVs. Samples preparations were achieved through four liquid-liquid extraction methods for lipids in order to achieve a broad coverage of lipid classes as well as high recovery and repeatability. Additionally, we demonstrated that a sonication-assisted homogenization step effectively facilitates lipid extraction from EVs. Through untargeted lipidomics, our study identifies and quantifies a diverse range of lipid species in human plasma (225 molecular lipids) and macrophage-derived EVs (124 molecular lipids) within different classes. Overall, we present an innovative methodology that combines pre-analytical lipid extraction techniques with high-resolution LC-MS/MS to enhance lipidomics research. This approach holds promise for personalized medicine and the discovery of novel lipid cargo associated with the various biological pathways involved with EVs biogenesis.

SARS-CoV-2 infection triggers distinct patterns of disease development characterized by significant alterations in host regulatory responses. Severe cases exhibit profound lung inflammation and systemic repercussions. Remarkably, critically ill patients display a “lipid storm”, influencing the inflammatory process and tissue damage. Sphingolipids (SLs) play pivotal roles in various cellular and tissue processes, including inflammation, metabolic disorders, and cancer. In this study, we employed high-resolution mass spectrometry to investigate SL metabolism in plasma samples obtained from control subjects (n = 55), COVID-19 patients (n = 204), and convalescent individuals (n = 77). These data were correlated with inflammatory parameters associated with the clinical severity of COVID-19. Additionally, we utilized RNAseq analysis to examine the gene expression of enzymes involved in the SL pathway. Our analysis revealed the presence of thirty-eight SL species from seven families in the plasma of study participants. The most profound alterations in the SL species profile were observed in patients with severe disease. Notably, a predominant sphingomyelin (SM d18:1) species emerged as a potential biomarker for COVID-19 severity, showing decreased levels in the plasma of convalescent individuals. Elevated SM levels were positively correlated with age, hospitalization duration, clinical score, and neutrophil count, as well as the production of IL-6 and IL-8. Intriguingly, we identified a putative protective effect against disease severity mediated by SM (d18:1/24:0), while ceramide (Cer) species (d18:1/24:1) and (d18:1/24:0)were associated with increased risk. Moreover, we observed the enhanced expression of key enzymes involved in the SL pathway in blood cells from severe COVID-19 patients, suggesting a primary flow towards Cer generation in tandem with SM synthesis. These findings underscore the potential of SM as a prognostic biomarker for COVID-19 and highlight promising pharmacological targets. By targeting sphingolipid pathways, novel therapeutic strategies may emerge to mitigate the severity of COVID-19 and improve patient outcomes.

SARS-CoV-2 infection triggers distinct patterns of disease development, characterized by significant alterations in host regulatory responses. Severe cases exhibit profound lung inflammation and systemic repercussions. Remarkably, critically ill patients display a "lipid storm", influencing the inflammatory process and tissue damage. Sphingolipids (SL) play pivotal roles in various cellular and tissue processes, including inflammation, metabolic disorders, and cancer. In this study, we employed high-resolution mass spectrometry to investigate SL metabolism in plasma samples obtained from control subjects (n=55), COVID-19 patients (n=204), and convalescent individuals (n=77). These data were correlated with inflammatory parameters associated with the clinical severity of COVID-19. Additionally, we utilized RNAseq analysis to examine the gene expression of enzymes involved in the SL pathway. Our analysis revealed the presence of thirty-eight SL species from seven families in the plasma of study participants. The most profound alterations in the SL species profile were observed in patients with severe disease. Notably, the predominant sphingomyelin (SM d18:1) species emerged as a potential biomarker for COVID-19 severity, showing decreased levels in the plasma of convalescent individuals. Elevated SM levels were positively correlated with age, hospitalization duration, clinical score, neutrophil count, as well as the production of IL-6 and IL-8. Intriguingly, we identified a putative protective effect against disease severity mediated by SM (d18:1/24:0), while ceramide (Cer) d18:1/24:1 and d18:1/24:0 was associated with increased risk. Moreover, we observed enhanced expression of key enzymes involved in SL pathway, in blood cells from severe COVID-19 patients, suggesting a primary flow towards Cer generation in tandem with SM synthesis. These findings underscore the potential of SM as a prognostic biomarker for COVID-19 and highlight promising pharmacological targets. By targeting sphingolipid pathways, novel therapeutic strategies may emerge to mitigate the severity of COVID-19 and improve patient outcomes.

A chemoenzymatic approach for the synthesis of α-N-heterocyclic ethyl- and phenylacetamides, levetiracetam analogs, is described. Eight nitrile substrates were prepared through the N-alkylation of heterocycles (2-pyrrolidinone, 2-piperidinone, 2-oxopiperazine and 1-methylpiperazine) directly from hydroxyl group of ethyl and phenyl α-hydroxynitriles with yield of 35−71% after 12 h. Twenty nitrile hydratases (NHases) were screened and showed that the N-derivatives lactam substrates led to their correspondent amides by Co-type NHase with conversion and enantiomeric excess of up to 47.5 and 52.3% for (S)-enantiomer, while the piperazine substrates underwent spontaneous decomposition by retro-Strecker reaction. In order to avoid a retro-Strecker reaction of α-aminonitriles, ionic liquids and polyethylene glycol (PEG400) were evaluated as alternative green solvents to aqueous buffered solutions in different proportions. Temperature was another parameter investigated during reaction-medium engineering for process optimization. However, unconventional reaction media and low temperature significantly reduced the NHase activity. The absolute configuration of α-N-heterocyclic ethyl- and phenylacetamides, some of which were new compounds, was determined using electronic circular dichroism (ECD) spectroscopy. Additionally, their potential as cholinesterase’s inhibitors was evaluated.

A chemoenzymatic approach for the synthesis of α-N-heterocyclic ethyl- and phenylacetamides, levetiracetam analogs, is described. Eight nitrile substrates were prepared through the N-alkylation of heterocycles (2-pyrrolidinone, 2-piperidinone, 2-oxopiperazine and 1-methylpiperazine) directly from hydroxyl group of ethyl and phenyl α-hydroxynitriles with yield of 35−71% after 12 h. Twenty nitrile hydratases (NHases) were screened and showed that the N-derivatives lactam substrates led to their correspondent amides by Co-type NHase with conversion and enantiomeric excess of up to 47.5 and 52.3% for (S)-enantiomer, while the piperazine substrates underwent spontaneous decomposition by retro-Strecker reaction. In order to avoid a retro-Strecker reaction of α-aminonitriles, ionic liquids and polyethylene glycol (PEG400) were evaluated as alternative green solvents to aqueous buffered solutions in different proportions. Temperature was another parameter investigated during reaction-medium engineering for process optimization. However, unconventional reaction media and low temperature significantly reduced the NHase activity. The absolute configuration of α-N-heterocyclic ethyl- and phenylacetamides, some of which were new compounds, was determined using electronic circular dichroism (ECD) spectroscopy. Additionally, their potential as cholinesterase’s inhibitors was evaluated.