Biology subjects

Roman, E.

Publications and source records attributed to Roman, E..

4 recordsLinked to original sources

bioRxiv2026

Functional specialization of OLMα2 interneurons emerges from differential longitudinal hippocampal-amygdala wiring

The ventral hippocampus (vHipp) is increasingly recognized for its role in processing probabilistic threats and emotional salience, yet the circuit mechanisms underlying these computations remain unclear. Here, we investigated how oriens-lacunosum moleculare interneurons expressing the 2 subunit of the nicotinic acetylcholine receptor (OLM2 cells) contribute to hippocampal function along the longitudinal axis. Combining cell-type specific optogenetics, behavioral assays, monosynaptic and transsynaptic viral tracing, we compared intermediate hippocampal (iHipp) and vHipp OLM2 populations. We show that OLM2 cells exert regionally distinct control over behavior. Manipulation of iHipp OLM2 cells selectively influenced object-directed exploration and novel object processing without affecting anxiety-like behavior, whereas vHipp OLM2 cells modulated arousal and emotionally driven avoidance without contributing to object memory. Circuit tracing revealed that this functional double dissociation is paralleled by distinct connectivity profiles: iHipp is preferentially embedded in sensory cortical networks, whereas vHipp is strongly connected to limbic structures, including the basolateral amygdala and nucleus accumbens. Notably, despite robust regional amygdala-hippocampal connectivity, OLM2 interneurons themselves received sparse direct amygdala input, indicating that emotional modulation is mediated indirectly via hippocampal pyramidal cell pathways. In contrast, stimulation of basolateral amygdala projections to vHipp promoted approach behavior without inducing generalized aversion, further supporting pathway- and cell-type specific encoding of valence and salience. Together, our findings demonstrate that OLM2 interneurons implement a longitudinally organized inhibitory framework in which conserved microcircuit motifs yield distinct behavioral outcomes, depending on their embedding within region specific input and output networks. This work identifies a mechanistic basis for functional specialization along the hippocampal axis and highlights interneuron positioning as a key determinant of hippocampal contributions to cognition and emotion.

neuroscience↗

bioRxiv2023

Interpretable Inflammation Landscape of Circulating Immune cells

Inflammation is a biological phenomenon involved in a wide variety of physiological and pathological processes. Although a controlled inflammatory response is beneficial for restoring homeostasis, it can become unfavorable if dysregulated. In recent years, major progress has been made in characterizing acute and chronic inflammation in specific diseases. However, a global, holistic understanding of inflammation is still elusive. This is particularly intriguing, considering the crucial function of inflammation for human health and its potential for modern medicine if fully deciphered. Here, we leverage advances in the field of single-cell genomics to delineate the full spectrum of circulating immune cell activation underlying inflammatory processes during infection, immune-mediated inflammatory diseases and cancer. Our single-cell atlas of >6.5 million peripheral blood mononuclear cells from 1047 patients and 19 diseases allowed us to learn a comprehensive model of inflammation in circulating immune cells. The atlas expanded our current knowledge of the biology of inflammation of immune-mediated diseases, acute and chronic inflammatory diseases, infection and solid tumors, and laid the foundation to develop a precision medicine framework using unsupervised as well as explainable machine learning. Beyond a disease-centered analysis, we charted altered activity of inflammatory molecules in peripheral blood cells, depicting discriminative inflammation-related genes to further understand mechanisms of inflammation. Finally, we have laid the groundwork for developing precision medicine diagnostic tools for patients experiencing pathologic inflammation by learning a classifier for inflammatory diseases, presenting cells in circulation as a powerful resource for patient diagnosis.

immunology↗

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↗