Biology subjects

Nichols, K.

Publications and source records attributed to Nichols, K..

3 recordsLinked to original sources

bioRxiv2024

Human Soluble Prorenin Receptor Expressed in Adipose Tissue Improves Insulin Sensitivity and Endothelial Function in Obese Female Mice

Soluble prorenin receptor (sPRR) is a component of the renin-angiotensin system (RAS) identified as a plasma biomarker for human metabolic disease. However, what tissue source of sPRR is implicated in the modulation of metabolic function remains unclear. This study investigated the contribution of human sPRR (HsPRR) produced in the adipose tissue (Adi) on the metabolic and cardiovascular function of lean and obese male and female mice. Adi-HsPRR mice, generated by crossing human sPRR-Myc-tag and Adiponectin/Cre mice, were fed a low-fat or high-fat diet (10% and 60% kCal from fat, respectively) for 20 weeks. Obese Adi-HsPRR mice showed elevated sPRR levels in adipose tissue without affecting adipocyte size or fat depot weight. Despite plasma sPRR being similar between obese Adi-HsPRR and control female mice, a positive correlation between plasma sPRR and adiposity was present only in controls. Obese Adi-HsPRR male mice showed elevated plasma sPRR compared with controls, but no correlation with adiposity was found in either group. Nevertheless, Adi-HsPRR expression improved insulin sensitivity and endothelial function, reduced adipogenic genes mRNA abundance (PPARg, SEBP1C and CD36), and increased plasma Angiotensin 1-7 levels only in obese HsPPR female mice. Taken together, elevated HsPRR in adipose tissue improved metabolic and vascular function in obese female mice despite normal circulating levels of sPRR, whereas increased local and circulating levels of HsPRR did not influence metabolic and cardiovascular function in obese male mice. Our data suggest that increased plasma sPRR associated with metabolic disease could be produced by other tissues rather than adipocytes.

physiology↗

bioRxiv2023

A Pumpless, High-Throughput Microphysiological SystemConfirms Enteric Innervation of Duodenal Epithelium Strengthensthe Barrier Function

Enteric neurons, diverse in function and great in number, are heavily involved in homeostasis within the small intestine and their dysregulation has been implicated in gastrointestinal disorders and neurodegenerative diseases. Innovations in biofabrication have resulted in advances for in vitro models of the gut, however the majority lack enteric innervation, limiting therapeutic screening and discovery. Here, we present a high-throughput co-cultured microphysiological system (MPS), or organ chip, that supports a primary epithelial monolayer that directly interfaces with a three-dimensional hydrogel containing a primary enteric neuron culture, mimicking the close proximity present in vivo. The acrylic MPS device was fabricated with our established and cost-effective laser cut and assemble method. We have expanded this technology to include up to twelve 3D MPSs per device within the footprint of a traditional well-plate, supporting high-throughput experimentation. The inclusion of this 3D microtissue does not hinder physiologically relevant flow, standard measures of barrier function, and microscopy techniques. The device features gravity-driven flow to induce physiological shear stress on the epithelium culture and provide continuous nutrient presentation. Results show the intestinal and neural tissue maintained expected morphologies over an experimental timeline of ten days. Proximal enteric neurons extend neurites through the 3D hydrogel towards the epithelial monolayer. Barrier function was confirmed with both Transepithelial Electrical Resistance (TEER) and Lucifer Yellow diffusion on-chip. TEER confirmed a significantly more substantial barrier integrity in co-cultures compared to baseline values (1.25-fold) in epithelial cell-only. Lucifer yellow permeability assays performed in parallel supported the TEER results, with an 11.8% lower permeability of the co-cultured group than the epithelium only. The presence of the ENS on chip results in a significant (1.4 fold) reduction in epidermal growth factor (EGF). This is the first high-throughput, innervated gut on a chip device that demonstrates the importance of the autonomic nervous system on EGF expression and possibly epithelial renewal in vitro. Innervation is essential to create more biomimetic and physiologically relevant in vitro models for biological and pharmacological assays.

bioengineering↗

bioRxiv2021

Dynamic structural cell responses in the thymus to acute injury, regeneration, and age

The thymus is essential for establishing adaptive immunity yet undergoes age-related atrophy leading to compromised immune responsiveness. The thymus is also extremely sensitive to acute insult and although capable of regeneration, this capacity declines with age. Focusing on non-hematopoietic stromal cells, and using single-cell and spatial transcriptomics, lineage-tracing, and advanced imaging, we discovered two atypical thymic epithelial cell (TEC) states that emerged with age. Age-associated (aa)TECs formed atypical high-density epithelial clusters that were devoid of thymocytes, an accretion of non-functional thymic tissue that worsened with age and exhibited features of partial epithelial-to-mesenchymal transition (EMT). In silico interaction analysis revealed that aaTEC emergence drew tonic signals from other TEC populations at baseline, acting as a sink for TEC growth factors. Following damage, aaTEC expanded substantially, further perturbing trophic pathways, and correlating with defective regeneration of the involuted thymus. These findings define a unique feature of thymic involution linked to immune aging.

immunology↗