Biology subjects

Elias, F.

Publications and source records attributed to Elias, F..

6 recordsLinked to original sources

bioRxiv2025

Novel Highly Homeostatic B Cells induced by Immunomodulatory Oligonucleotide IMT504

Cellular homeostasis depends on endoplasmic reticulum (ER) function and is highly sensitive to ER stress typically triggered by protein-folding overload. To restore balance, eukaryotic cells engage the unfolded protein response (UPR), a network of signaling pathways that enhances resistance to stress by upregulating chaperones, reducing global translation, and promoting degradation of unfolded proteins via autophagy. Additional stress-sensing pathways, including the NRF2 antioxidant response and the AMPK energy-sensing axis, converge to reinforce cellular homeostasis. In pathological conditions, reinforcing immune homeostasis constitutes a promising therapeutic strategy. Among emerging pharmacological agents that activate endogenous protective pathways, the synthetic immunomodulatory oligonucleotide IMT504 has shown favorable pharmacokinetics and stability in preclinical models, although its mechanisms of action remain unclear. Using purified human CD19 B cells, we investigated the cellular, molecular, and transcriptional responses to IMT504 stimulation, to uncover new insights into its mode of action and broader implications for immune-mediated homeostasis. We discovered that incubation of CD19CD27- B cells with IMT504 directly induces a-previously unreported-subpopulation of human B cells, which we termed B homeostatic cells (Bhom). These Bhom cells display a distinctive phenotype (CD27-CD24CD38CD138-MUC1) and upregulate genes associated with mitochondrial metabolism, proteostasis, antioxidant defense, and survival. Promoter analysis of the most highly upregulated genes revealed an Invariant Gene Transcriptional Regulator (IGTR) signature with binding motifs for MYC, CREB1, CTCF, EP300 and NRF1/NRF2, suggesting a coordinated transcriptional control of the involved homeostatic programs. Network analysis linked NRF1 to SIRT1/PGC1 metabolic axis and NRF2 to IGTR-regulated factors. Furthermore, we found that IMT504 binds ATP-citrate lyase (ACLY), an endogenous repressor of AMPK, indicating that IMT504 may activate AMPK-dependent autophagy and downstream NRF1/NRF2 signaling. Altogether, these findings identify Bhom cells as a novel B-cell subset that embodies homeostatic features and reveal IMT504 as a potent inducer of B-cell-mediated homeostasis through AMPK-driven transcriptional reprogramming. This mechanism strongly supports IMT504 as a promising candidate for immune-modulatory therapies aimed at restoring immune homeostasis. SIGNIFICANCE STATEMENTThe discovery of a novel B-cell subset, termed B homeostatic cells (Bhom), reveals a previously unrecognized axis of immune response. Incubation of human CD19CD27-B cells with the immunomodulatory oligonucleotide IMT504 directly induces Bhom cells. Its differentiation engages a conserved transcriptional network centered on AMPK-NRF1/NRF2 signaling, highlighting a potential therapeutic pathway to restore or enhance immune homeostasis.

immunology↗

bioRxiv2025

Hyperdominance and rarity in Amazonian secondary forests

Recent studies have shown that a few tree species dominate abundance and carbon storage in undisturbed Amazonian forests. However, this pattern remains poorly understood in forests regrowing after deforestation. Understanding dominance patterns in secondary forests is important as it could improve insights into their functioning and guide management and restoration efforts. We used unweighted and novel plot-weighted approaches to assess hyperdominance in abundance and carbon storage of trees and palms during secondary forest recovery, using data from 102 plots across four regions in the eastern Amazon, separated by an average distance of 600 km (range: 150-1,000 km). Secondary forests show extreme hyperdominance in all approaches, with just 16-25 species ([~]3.6-5.6%) accounting for over 50% of abundance and carbon storage. A small subset of species ([~]9%) were found across all regions and successional stages, highlighting their key role in ecosystem structure and function during forest regrowth. Annona exsucca, Cecropia palmata, Tapirira guianensis, Inga alba, Attalea maripa, Amphiodon effusus, Banara guianensis, and Vismia guianensis consistently emerged as hyperdominant across stem size classes, approaches, and metrics, jointly accounting for roughly 16-27% of total abundance and carbon in Amazonian secondary forests. For larger stems >10cm DBH, hyperdominant species exhibited lower wood density compared to non-hyperdominant species across all successional stages, suggesting these specialist pioneers have distinct ecological strategies from the rest of the community. Our findings indicate that secondary forest functioning can be largely predicted by a relatively limited set of species, providing a framework for future research ranging from ecophysiology to remote sensing of canopy traits and restoration planning.

ecology↗

bioRxiv2021

Height-diameter allometry for tropical forest in northern Amazonia

Height measurements are essential to manage and monitor forest biomass and carbon stocks. However, accurate estimation of this variable in tropical ecosystems is still difficult due to species heterogeneity and environmental variability. In this article, we compare and discuss six nonlinear allometric models parameterized at different scales (local, regional and pantropical). We also evaluate the height measurements obtained in the field by the hypsometer when compared with the true tree height. We used a dataset composed of 180 harvested trees in two distinct areas located in the Amapa State. The functional form of the Weibull model was the best local model, showing similar performance to the pantropical model. The inaccuracy detected in the hypsometer estimates reinforces the importance of incorporating new technologies in measuring individual tree heights. Establishing accurate allometric models requires knowledge of ecophysiological and environmental processes that govern vegetation dynamics and tree height growth. It is essential to investigate the influence of different species and ecological gradients on the diameter/height ratio.

ecology↗

bioRxiv2021

Production of a Highly Immunogenic Antigen from SARS-CoV-2 by Covalent Coupling of the Receptor Binding Domain of Spike Protein to a Multimeric Carrier

Since the discovery of SARS-CoV-2, several antigens have been proposed to be part of COVID-19 vaccines. The receptor binding domain (RBD) of Spike protein is one of the promising candidates to develop effective vaccines since it can induce potent neutralizing antibodies. We previously reported the production of RBD in Pichia pastoris and showed it is structurally identical to the protein produced in mammalian HEK-293T cells. In this work we designed an RBD multimer construct with the purpose of increasing RBD immunogenicity. We produced multimeric particles by a transpeptidation reaction between the RBD expressed in P. pastoris and Lumazine Synthase from Brucella abortus (BLS), which is a highly immunogenic and very stable decameric protein of 170 kDa. We vaccinated mice with two doses 30 days apart, and then we measured humoral immune response. When the number of RBD copies coupled to BLS was high (6-7 RBD molecules per BLS decamer, in average), the immune response was significantly better than that elicited by RBD alone or even by RBD-BLS comprising low number of RBD copies (1-2 RBD molecules per BLS decamer). Remarkably, the construct with high number of RBD copies induced high IgG titers with high neutralizing capacity. Furthermore, a superior immune response was observed when Al(OH)3 adjuvant was added to this formulation, exhibiting a higher titer of neutralizing antibodies. Altogether our results suggest that RBD covalent coupled to BLS forming a multimer-particle shows an advantageous architecture to the antigen-presentation to the immune system which enhances immune responses. This new antigen should be considered a potent candidate for a protein-based vaccine.

biochemistry↗

bioRxiv2020

Structural and Functional Comparison of SARS-CoV-2-Spike Receptor Binding Domain Produced in Pichia pastoris and Mammalian Cells

The yeast Pichia pastoris is a cost-effective and easily scalable system for recombinant protein production. In this work we compared the conformation of the receptor binding domain (RBD) from SARS-CoV-2 Spike protein expressed in P. pastoris and in the well established HEK-293T mammalian cell system. RBD obtained from both yeast and mammalian cells was properly folded, as indicated by UV-absorption, circular dichroism and tryptophan fluorescence. They also had similar stability, as indicated by temperature-induced unfolding (observed Tm were 50 {degrees}C and 52 {degrees}C for RBD produced in P. pastoris and HEK-293T cells, respectively). Moreover, the stability of both variants was similarly reduced when the ionic strength was increased, in agreement with a computational analysis predicting that a set of ionic interactions may stabilize RBD structure. Further characterization by HPLC, size-exclusion chromatography and mass spectrometry revealed a higher heterogeneity of RBD expressed in P. pastoris relative to that produced in HEK-293T cells, which disappeared after enzymatic removal of glycans. The production of RBD in P. pastoris was scaled-up in a bioreactor, with yields above 45 mg/L of 90% pure protein, thus potentially allowing large scale immunizations to produce neutralizing antibodies, as well as the large scale production of serological tests for SARS-CoV-2.

biochemistry↗

bioRxiv2018

Deregulation of VEGFR-2 and PGFR expression and microvascular density in a triple-negative model of canine malignant mammary tumors with lymph node or lung metastasis

Canine mammary tumors (CMT) are the most common cancer in noncastrated female dogs. Interestingly, triple-negative tumors are the most common molecular subtype in female dogs. In this study, we proposed to evaluate the expression of VEGFR-2, PDGFR and microvascular density (MVD) in a group of metastatic and nonmetastatic triple-negative CMT and compare the expression based on clinical parameters. Twenty-six female dogs with triple-negative mammary tumors were divided into three groups: nonmetastatic tumors (NMT) (N=11), tumors with lymph node metastasis (LNM) (N=10) and tumors with lung metastasis (LM) (N=5). We observed increased VEGFR-2 expression in LNM compared with NMT and a positive correlation between tumor grade and VEGFR-2 expression. A positive correlation was noted between VEGFR-2 and PDGFR expression. Regarding microvascular density (MVD), we identified a higher number of vessels in primary tumors with lymph node metastasis and lung metastasis compared with tumors with no metastasis. The primary tumors with lung metastasis exhibited an increased MVD compared with carcinoma with lymph node metastasis. Overall, our results suggest a deregulation of VEGFR-2 and PDGFR and high MVD in metastatic tumors, indicating a role for angiogenesis in tumor progression.

cancer biology↗