Biology subjects

Karakach, T.

Publications and source records attributed to Karakach, T..

4 recordsLinked to original sources

bioRxiv2025

Persistent glycolysis defines the foreign body response to polymeric implants.

Non-degradable polymeric implantable medical devices are a mainstay of modern healthcare but can frequently lead to severe complications. These complications are largely attributable to the foreign body response (FBR), which is characterized by excessive inflammation and fibrosis in response to implanted materials. The pathologic mechanisms underpinning the FBR remain elusive; however, metabolism is increasingly regarded as a critical regulator of innate immune function. We conducted comprehensive metabolic profiling of implant-associated macrophages and multinucleated giant cells in response to the subcutaneous implantation of clinically relevant implantable materials in a mouse model of implant fibrosis. Leveraging novel metabolic characterization methods for analysis of both metabolic dependence and enzyme expression in heterogeneous peri-implant tissues, we demonstrate that peri-implant macrophages are glycolytic at least up to six weeks post-implantation. Glycolytically dependent peri-implant macrophages expression of glucose transporter 1 (GLUT1) increased temporally and with proximity to the implant-tissue interface. Paired rate-limiting metabolic enzyme expression analysis showed notable increases in biosynthetic pathways (G6PD and ACC1), matched with increased mitochondrial staining intensity in GLUT1Hi cells at chronic timepoints, which were not notable at early timepoints. Notably, we identified a glycolytic dependence of multinucleated macrophages associated with polymeric materials: these cells expressed higher levels of GLUT1 than mononuclear macrophages of comparable metabolic phenotype. Our findings highlight GLUT1-dependent glycolysis as the definitive metabolic system used by peri-implant macrophages and multinucleated cells in the FBR, highlighting this pathway as a potential target for the development of novel therapeutic approaches.

immunology↗

bioRxiv2023

Immuno-informatics Study Identifies Conserved T Cell Epitopes in Non-structural Proteins of Bluetongue Virus Serotypes: Formulation of Computationally Optimized Next-Generation Broad-spectrum Multiepitope Vaccine

Bluetongue (BT) is a significant arboviral disease affecting sheep, cattle, goats, and wild ruminants, posing serious economic challenges to livestock industry. Control efforts have been hampered by the existence of over 32 distinct BT virus (BTV) serotypes and the absence of broad-spectrum vaccines. Some key non-structural proteins of BTV, including NS1, NS2, and NS3, exhibit notable amino acid sequence conservation. Our findings reveal that mouse MHC class I (MHC-I) CD8+ T cell epitopes are highly conserved in NS1 and NS3, while MHC-II epitopes are prevalent in all the three non-structural NS 1-3 proteins. Similarly, both class I and II Bovine Leukocyte antigen-restricted CD8+ and CD4+ T cell epitopes are conserved within NS1, NS2, and NS3 proteins. To construct in silico broad-spectrum vaccine, we subsequently screened these conserved epitopes based on antigenicity, allergenicity, toxicity, and solubility. Modeling and Refinement of the 3D structure models of vaccine constructs were achieved using protein modeling web servers. Our analysis revealed promising epitopes that exhibit strong binding affinities with low energies against two TLR receptors (TLR3 and TLR4). To ensure atomic-level stability, we evaluated the docking complexes of epitopes and receptors through all-atom molecular dynamics simulations (MDS). Encouragingly, our 100 nanoseconds MDS showed stable complexes with minimal RMSF values. Our study offers valuable insights into these conserved T cell epitopes as promising candidates for a broad-spectrum BT vaccine. We therefore encourage for their evaluation in animal models and natural hosts to assess their immunogenicity, safety, and efficacy for field use in the livestock.

bioinformatics↗

bioRxiv2023

Valvular Prostaglandins are Elevated in Severe Human Aortic Valve Stenosis

IntroductionAortic valve stenosis (AVS) is the most common valvular disease in the developed world. AVS involves the progressive fibro-calcific remodeling of the aortic valve (AV), which impairs function and can ultimately lead to heart failure. Due to gaps in our understanding of the underlying mechanisms of AVS, there are no pharmacological treatments nor dietary interventions known to slow AVS progression. Recent studies have begun to suggest oxylipins, a class of bioactive lipid, may be dysregulated in the valves of AVS-patients. MethodologyWe utilized HPLC-MS/MS to conduct a targeted oxylipin analysis on human AV tissue and plasma from a cohort of 110 patients undergoing AV surgery. ResultsWe identified 36 oxylipins in human AV tissue with all showing significant increase in patients with severe AVS. A multivariate model including patient characteristics and valvular oxylipins identified arachidonic acid-cyclooxygenase (COX) pathway derived prostanoids to be the most associated with AVS severity. Plasma oxylipin levels were measured in a subset of aortic surgery patients and compared to a control group of healthy participants, showing distinct oxylipin profiles between control and disease. ConclusionOur comprehensive analysis of oxylipins in the human AV to date and identified the inflammatory and osteogenic regulating prostanoids to be positively correlated with AVS severity. This elucidation of prostanoid dysregulation warrants further research into COX inhibition to mitigate AVS.

physiology↗

bioRxiv2021

CD8+ T Cell Metabolic Rewiring Defined by Single-Cell RNA-Sequencing Identifies a Critical Role of ASNS Expression Dynamics in T Cell Differentiation

Cytotoxic T cells dynamically rewire their metabolism during the course of an immune response. While T-cell metabolism has been extensively studied at phenotypic endpoints of activation and differentiation, the underlying dynamics remain largely elusive. Here, we leverage on single-cell RNA-sequencing (scRNA-seq) measurements of in vitro activated and differentiated CD8+ T cells cultured in physiological media to resolve these metabolic dynamics. We find that our scRNA-seq analysis identifies most metabolic changes previously defined in in vivo experiments, such as a rewiring from an oxidative to an anabolism-promoting metabolic program during activation to an effector state, which is later reverted upon memory polarization. Importantly, our scRNA-seq data further provide a dynamic description of these changes. In this sense, our data predict a differential time-dependent reliance of CD8+ T cells on the synthesis versus uptake of various non-essential amino acids during T-cell activation, which we corroborate with additional functional in vitro experiments. We further exploit our scRNA-seq data to identify metabolic genes that could potentially dictate the outcome of T-cell differentiation, by ranking them based on their expression dynamics. Among the highest-ranked hits, we find asparagine synthetase (Asns), whose expression sharply peaks for effector CD8+ T cells and further decays towards memory polarization. We then confirm that these in vitro Asns expression dynamics are representative of an in vivo situation in a mouse model of viral infection. Moreover, we find that disrupting these expression dynamics in vitro, by depleting asparagine from the culture media, delays central-memory polarization. Accordingly, we find that preventing the decay of ASNS by stable overexpression at the protein level in vivo leads to a significant increase in effector CD8+ T-cell expansion, and a concomitant decrease in central-memory formation, in a mouse model of viral infection. This shows that ASNS expression dynamics dictate the fate of CD8+ T-cell differentiation. In conclusion, we provide a resource of dynamic expression changes during CD8+ T-cell activation and differentiation that is expected to increase our understanding of the dynamic metabolic requirements of T cells progressing along the immune response cascade.

immunology↗