Biology subjects

Akbari, M.

Publications and source records attributed to Akbari, M..

6 recordsLinked to original sources

bioRxiv2024

Maternal humoral factors modulate offspring gut immune homeostasis to mitigate diabetes development

Environmental risk factors possess the potential to modulate the pathogenesis of type I diabetes (T1D). Foremost among these factors are early life influences impacting the gastrointestinal (GI) tract. During infancy, both the microbiota and immune system are influenced by maternal factors contributing to key events in the neonatal GI tract. Despite the well-known importance of maternal factors on infant immune development, whether maternal immune dysregulation and dysbiosis can perpetuate the same in offspring remains largely unknown. To explore how these maternal factors impact offspring disease development, we used IgA-deficiency induced maternal dysbiosis in Non-Obese Diabetic (NOD) dams to study T1D development in their progeny. We found that maternal dysbiosis and absence of IgA led to changes in IgA-sufficient offspring immune development resulting in heightened GI immune activity. Maternal dysbiosis also contributed to altered microbiome establishment in progeny, such that pups exhibited reduced colonic abundance of Akkermansia muciniphila and Clostridoides difficile. In adulthood, these mice exhibited a lowered incidence of T1D. This protection was replicated by fostering high incidence offspring to dysbiotic dams, prompting us to propose that altered breast milk composition in dysbiotic dams can influence immune development and microbiome establishment in offspring, contributing to T1D resistance.

immunology↗

bioRxiv2024

The role of YAP/TAZ signaling in dendritic cell-mediated pathogenesis of insulin resistance and non-alcoholic fatty liver disease

Obesity and insulin resistance (IR) are global health challenges linked to metabolic diseases, such as type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). High-caloric intake, which is associated to NAFLD, induces adipocyte hypertrophy and inflammation, triggering dendritic cell (DC) activation and systemic inflammation. DC exacerbate inflammation by promoting pro-inflammatory responses, aggravating IR and NAFLD progression. NAFLD is characterized by liver fibrosis, which alters tissue stiffness that can trigger mechanosensing pathways such as the Hippo pathway in immune cell types. In this work we explored the roles of key mediators of the Hippo pathway, YAP and TAZ, in DCs within the context of liver fibrosis, obesity and IR, using a model of NAFLD induced by feeding a high fat high sucrose diet. Our findings indicate that specific deletion of YAP and/or TAZ in DCs had minimal impact on IR development and metabolic tissue inflammation. We conclude that YAP and TAZ have limited and possibly redundant roles in the immune pathophysiology of NAFLD and IR.

immunology↗

bioRxiv2024

Developing a Soft Micropatterned Substrate to Enhance Maturation of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes (hiPSC-CMs)

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) offer numerous advantages as a biological model, yet their inherent immaturity compared to adult cardiomyocytes poses significant limitations. This study addresses hiPSC-CM immaturity by introducing a novel physiologically relevant micropatterned substrate for long-term culture and maturation. A novel microfabrication technique combining laser etching and casting creates a micropatterned polydimethylsiloxane (PDMS) substrate with varying stiffness, from 2 to 50 kPa, mimicking healthy and fibrotic cardiac tissue, respectively. Platinum electrodes integrated into the cell culture chamber enabled pacing of cells at various frequencies. Subsequently, cells were transferred to the incubator for time-course analysis, ensuring contamination-free conditions. Cell contractility, cytosolic Ca2+ transient, sarcomere orientation, distribution, and nucleus aspect ratio are analyzed in a 2D hiPSC-CM monolayer up to 90 days post-replating in relation to substrate micropattern dimensions. Culturing hiPSC-CMs for three weeks on a micropatterned PDMS substrate (2.5-5 {micro}m deep, 20 {micro}m center-to-center spacing of grooves, 2-5 kPa stiffness) emerges as optimal for cardiomyocyte alignment, nucleus aspect ratio, contractility, and cytosolic Ca2+ transient. The study provides significant insights into substrate stiffness effects on hiPSC-CM contractility and Ca2+ transient at immature and mature states. Maximum contractility and fastest Ca2+ transient kinetics occur in mature hiPSC-CMs cultured for two to four weeks, with the optimum at three weeks, on a soft micropatterned PDMS substrate. This new substrate offers a promising platform for disease modeling and therapeutic interventions.

bioengineering↗

bioRxiv2024

Tumoroid-on-a-Plate (ToP): Physiologically Relevant Cancer Model Generation and Therapeutic Screening

Employing three-dimensional (3D) in vitro models, including tumor organoids and spheroids, stands pivotal in enhancing cancer therapy. These models bridge the gap between 2D cell cultures and complex in vivo environments, effectively mimicking the intricate cellular interplay and microenvironmental factors found in solid tumors. Consequently, they offer versatile tools for comprehensive studies into cancer progression, drug responses, and tailored therapies. In this study, we present a novel open-surface microfluidic-integrated platform called the Tumoroid-on-a-Plate (ToP) device, designed for generating intricate predictive 3D solid tumor models. By incorporating a tumor mass, stromal cells, and extracellular matrix components, we successfully replicate the complexity of glioblastoma (GBM) and pancreatic adenocarcinoma (PDAC) within our system. Using our advanced ToP model, we were able to successfully screen the effect of various GBM extracellular matrix compositions, such as Collagen and Reelin, on the invasiveness of the GBM cells with the ToP model. The ToP in vitro model also allowed for the screening of chemotherapeutic drugs such as temozolomide and iron-chelators in a single and binary treatment setting on the complex ECM-embedded tumoroids. This helped to investigate the toxic effect of different therapeutics on the viability and apoptosis of our in vitro GBM and PDAC cancer models. Additionally, by co-culturing human-derived fibroblast cells with PDAC tumoroids, the pro-invasive impact of the stromal component of the tumor microenvironment on growth behaviour and drug response of the tumoroids was revealed. This study underscores the transformative role of predictive 3D models in deciphering cancer intricacies and highlights the promise of ToP in advancing therapeutic understanding.

bioengineering↗

bioRxiv2024

Metabolic Vulnerabilities of Temozolomide-Resistant Glioblastoma Cells: Implications for Targeted Therapies and Overcoming Chemoresistance

Chemoresistance is a major clinical challenge in the management of glioblastoma (GB), making it difficult to achieve long-term success with traditional treatments. Therefore, there is a need for the development of novel drugs. We explored the metabolic vulnerabilities of temozolomide (TMZ)-resistant GB and their potential implications for targeted therapies. In monolayer and tumoroid cultures, we found elevated reliance on oxidative phosphorylation in TMZ-resistant cells. Notably, iron reduction in TMZ-resistant cells reduced viability and proliferation, upregulated hypoxia-inducible factor 1- (Hif1-) expression, induced autophagy, inhibited autophagic flux, and increased reactive oxygen species (ROS) generation, indicating the significance of iron in metabolic vulnerabilities of these cells. Hypoxic cells showed acquired resistance to iron chelation compared to their normoxic state, suggesting an adaptive mechanism associated to hypoxia. Viability, size, and invasion were reduced in TMZ-resistant tumoroids. Additionally, we reported IC50 for the combination of TMZ with a range of DFO and DFP, making the combination therapy a promising drug candidate to improve therapeutic treatments. TeaserCombining iron reduction and chemotherapy in drug-resistant glioblastoma cells enhances therapeutic outcomes.

cancer biology↗

bioRxiv2022

A multi-omics analysis of glioma chemoresistance using a hybrid microphysiological model of glioblastoma

Chemoresistance is a major clinical challenge in the management of glioblastoma (GBM) Temozolomide (TMZ) is the chemotherapeutic drug of choice for GBM; however, the therapeutic effect of TMZ is limited due to the development of resistance. Recapitulating GBM chemoresistance in a controlled environment is thus essential in understanding the mechanism of chemoresistance. Herein, we present a hybrid microphysiological model of chemoresistant GBM-on-a-chip (HGoC) by directly co-culturing TMZ-resistant GBM spheroids with healthy neurons to mimic the microenvironment of both the tumor and the surrounding healthy tissue. We characterized the model with proteomics, lipidomics, and secretome assays. The results showed that our artificial model recapitulated the molecular signatures of recurrent GBM in humans. Both showed alterations in vesicular transport and cholesterol pathways, mitotic quiescence, and a switch in metabolism to oxidative phosphorylation associated with a transition from mesenchymal to amoeboid. This is the first report to unravel the interplay of all these molecular changes as a mechanism of chemoresistance in glioblastoma. Moreover, we have shown that the acquisition of resistance increases invasiveness and the presence of neurons decreases this property.

bioengineering↗