Biology subjects

Mohana-Borges, R.

Publications and source records attributed to Mohana-Borges, R..

4 recordsLinked to original sources

bioRxiv2025

Interplay between Hyperglycemia and Chikungunya Virus Infection: Pathophysiological Insights from Murine Model

Chikungunya fever (CHIKF) is a re-emerging viral disease characterized by acute systemic manifestations and debilitating musculoskeletal symptoms that can persist after viral clearance. Although typically self-limiting in healthy individuals, clinical outcomes are significantly worsened in patients with pre-existing comorbidities, particularly diabetes mellitus (DM). Epidemiological data links DM to heightened CHIKF severity and a greater risk of developing chronic arthropathy, yet the mechanism underpinning this association remains poorly understood. In this study, we established an in vivo streptozotocin (STZ)-induced diabetic C57BL/6 mice as a model to investigate the impact of DM on CHIKV pathogenesis. STZ induces selective pancreatic {beta}-cell destruction and persistent hyperglycemia. Diabetic animals infected with CHIKV exhibited aggravated joint inflammation, increased nociceptive sensitivity, and elevated serum markers of muscle and hepatic injury, including creatine kinase (CK) and alanine aminotransferase (ALT). Histopathological analyses revealed that CHIKV infection alone disrupted joint architecture. However, in the diabetic context, these alterations were significantly exacerbated, with enhanced inflammatory infiltrates, chondrocyte loss, osteocyte necrosis, and fibrotic remodeling. These results demonstrate that the diabetic metabolic environment profoundly amplifies CHIKV-induced tissue damage and impairs resolution of inflammation, offering a plausible mechanistic explanation for the poorest CHIKF outcomes observed in diabetic patients. Thus, this model provides a valuable platform for exploring the molecular drivers of CHIKF severity and chronicity, especially among DM patients, as well as for development of pharmacological tools to mitigate CHIKV-associated complications in metabolically vulnerable populations. ImportanceChikungunya virus is responsible for a re-emerging disease that causes intense joint pain and long-lasting inflammation, especially in vulnerable individuals. People with diabetes are known to suffer more severe and persistent symptoms, but the biological reasons behind this have remained unclear. In this study, we used a diabetic mouse model to investigate how a high-glucose environment influences the course of Chikungunya virus infection. We found that diabetic mice experienced more intense joint damage, increased pain sensitivity, and signs of broader organ injury compared to non-diabetic animals. Microscopic analyses of tissues showed greater inflammation and structural damage in the joints of diabetic animals. These findings suggest that diabetes directly worsens the effects of Chikungunya virus infection by amplifying inflammation and delaying healing. This model helps explain why diabetic patients have worse outcomes and may assist in developing new treatments to protect high-risk populations from long-term complications of this infection.

immunology↗

bioRxiv2022

Acquiring thin histological sections of acai(Euterpe oleracea Mart.) seeds for molecular mapping by mass spectrometry imaging

RATIONALEMatrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) of tissues became popular in the last decade. Consequently, adapting sample preparation methods for different materials turned to be a pivotal step for a successful analysis, due to the requirement of samples slices of 12-20 m thickness. However, preparing thin sections compatible with MALDI-IMS for unusual samples is challenging, as existing histological protocols may not be suitable, thus requiring new methods. Acai (Euterpe oleracea Mart.) seed is an example of a challenging material due to its toughness and resistance to crack. Therefore, our goal was to develop a methodology to obtain thin (<20 m) and entire longitudinal sections of acai seeds for MALDI-IMS analysis. METHODSDifferent strategies were evaluated for obtaining thin cuts of seeds, being the combination of the following steps the most suitable option: (i) softening of seeds by water immersion for 24 h; (ii) longitudinal cut of seeds to obtain half-seeds using a razor blade and a hammer; (iii) half-seeds imbibition in gelatin; (iv) sectioning using a cryostat at -20 {degrees}C to obtain samples with <20 m thickness; and (v) collection of samples in an indium tin oxide coated glass slide covered by a double-face copper tape to avoid sample wrapping and ensure adhesion after unfreezing. (iv) storage of samples in a -80 {degrees}C freezer, if necessary. RESULTSAs a result, this adapted sample preparation method enabled the analysis of acai seeds by MALDI-IMS providing spatial distribution of carbohydrates in the endosperm. CONCLUSIONSThe adaptations developed for sample preparation will help investigate the metabolic and physiological properties of acai seeds in future studies.

plant biology↗

bioRxiv2020

Sustained antibody response to ZIKV infection induced by NS1 protein is accompanied by the progressive appearance of autoreactive antibodies and cross-reactive B cell clones.

Besides antigen-specific responses to viral antigens, humoral immune response in virus infection can generate polyreactive and autoreactive antibodies. Dengue and Zika virus infections have been linked to antibody-mediated autoimmune disorders including Guillain-Barre syndrome. A unique feature of flaviviruses is the secretion of non-structural protein 1 (NS1) by infected cells. NS1 is highly immunogenic and antibodies targeting NS1 can have both protective and pathogenic roles. In the present study, we investigated the humoral immune response to Zika virus NS1 and found NS1 to be an immunodominant viral antigen associated with the presence of autoreactive antibodies. Through single B cell cultures, we coupled binding assays and BCR sequencing, confirming the immunodominance of NS1. Of note, we demonstrate the presence of self-reactive clones in germinal centers after both infection and immunization, some of which clones presenting cross-reactivity with NS1. Sequence analysis of anti-NS1 B cell clones showed sequence features associated with pathogenic autoreactive antibodies. Our findings demonstrate NS1 immunodominance at the cellular level as well as a potential role for NS1 in ZIKV associated autoimmune manifestations.

immunology↗

bioRxiv2020

Updates on enzymatic and structural properties of human glutamine: fructose-6-phosphate amidotransferase 2 (hGFAT2)

Glycoconjugates play a central role in several cellular processes and alteration in their composition is associated to human pathologies. The hexosamine biosynthetic pathway is a route through which cells obtain substrates for cellular glycosylation, and is controlled by the glutamine: fructose-6-phosphate amidotransferase (GFAT). Human isoform 2 GFAT (hGFAT2) has been implicated in diabetes and cancer, however, there is no information about structural and enzymatic properties of this enzyme. Here, we report a successful expression and purification of a catalytically active recombinant hGFAT2 (rhGFAT2) in E. coli cells fused or not to a HisTag at the C-terminal end. Our enzyme kinetics data suggest that hGFAT2 does not follow the ordered bi-bi mechanism, and performs the glucosamine-6-phosphate synthesis much slowly than previously reported for other GFATs. In addition, hGFAT2 is able to isomerase fructose-6-phosphate into glucose-6-phosphate even in presence of equimolar amounts of glutamine, in an unproductive glutamine hydrolysis. Structural analysis of the generated three-dimensional model rhGFAT2, corroborated by circular dichroism data, indicated the presence of a partially structured loop in glutaminase domain, whose sequence is present in eukaryotic enzymes but absent in the E. coli homolog. Molecular dynamics simulations show such loop as the most flexible portion of the protein, which interacts with the protein mainly through the interdomain region, and plays a key role on conformational states of hGFAT2. Altogether, our study provides the first comprehensive set of data on the structure, kinetics and mechanics of hGFAT2, which will certainly contribute for further studies focusing on drug development targeting hGFAT2.

biochemistry↗