Biology subjects

Brookens, S. K.

Publications and source records attributed to Brookens, S. K..

3 recordsLinked to original sources

bioRxiv2025

Synthetic auxotrophy reveals metabolic regulation of plasma cell generation, affinity maturation, and cytokine receptor signaling

The efficiencies with which activated B lymphocytes proliferate and develop into antibody (Ab)-secreting plasma cells are critical determinants of adaptive humoral immunity and sustain certain autoimmune diseases. Specific pathways in intermediary metabolism, or their substrate supply, influence lymphocyte differentiation and function. We now show that although stringent restriction of glutamine supply decreases proliferation and differentiation of B cells into plasma cells, glutaminolysis - a major means of metabolism of this amino acid - was only conditionally crucial in B cells and the Ab responses derived from them. Strikingly, Gls, the gene encoding the main glutaminase of lymphocytes, promoted anti-NP Ab responses at the primary and recall phases if either glucose uptake into B cells or pyruvate into their mitochondria was also impaired but otherwise was dispensable. This synthetic auxotrophy, i.e., conditional requirement of glutaminase for processes in addition to survival and proliferation, involved support to a progressive expansion of mitochondrial respiration followed by plasma cell differentiation. Surprisingly, impairment of glutaminase and the mitochondrial pyruvate channel decreased IL-21 stimulation of STAT3 phosphorylation as well as interferon stimulation of STAT1 activation. Together, our findings establish not only a powerful collaboration of metabolic pathways in programming increased respiration and the development of Ab-secreting cells, but also reveal modulation of cytokine receptor signaling by metabolism.

immunology↗

bioRxiv2025

OxLDL-targeted Chimeric Antigen Receptor T Regulatory Cells Reduce Atherosclerotic Plaque Development

Cardiovascular disease caused by atherosclerosis is responsible for 18 million deaths annually, highlighting a significant need for new medical therapies, especially for patients ineligible for surgical interventions. Atherosclerosis is driven by the accumulation of low-density lipoprotein (LDL) and the formation of foam cells, accompanied by oxidative stress and the deposition of oxidized LDL (OxLDL), a pro-inflammatory molecule. Lowering LDL is the mainstay of current medical treatment in addition to blood pressure control and lifestyle changes, but to date, specifically targeting the inflammatory pathways contributing to plaque development without significant systemic side effects has not been feasible. Over the past decade, chimeric antigen receptor (CAR) T cells have treated cancer and restored immune imbalance in autoimmune diseases in patients and resolved cardiac fibrosis in preclinical models. Using an inducible T regulatory cell (Treg) platform, we created an anti-OxLDL-specific CAR Treg therapy that exerts cell- and cytokine-mediated immunosuppression to reduce macrophage-foam cell formation in vitro. Murine anti-OxLDL CAR Tregs inhibited 80% of atherosclerotic plaque formation in immunocompetent mouse models of hyperlipidemia and atherosclerosis. These studies illustrate the potential of anti-OxLDL CAR Tregs to mitigate the inflammation and plaque deposition associated with OxLDL, potentially offering a new therapeutic option for atherosclerosis.

synthetic biology↗

bioRxiv2023

Plasma cell differentiation, antibody quality, and initial germinal center B cell population depend on glucose influx rate

Antibody secretion into sera, selection for higher affinity BCR, and the generation of higher Ab affinities are important elements of immune response optimization, and a core function of germinal center reactions. B cell proliferation requires nutrients to support the anabolism inherent in clonal expansion. Glucose usage by GC B cells has been reported to contribute little to their energy needs, with questions raised as to whether or not glucose uptake or glycolysis increases in GC B cells compared to their naive precursors. Indeed, metabolism can be highly flexible, such that supply shortage along one pathway may be compensated by increased flux on others. We now show that elimination of the glucose transporter GLUT1 after establishment of a pre-immune B cell repertoire, even after initiation of the GC B cell gene expression program, decreased initial GC B cell population numbers, affinity maturation, and PC outputs. Glucose oxidation was heightened in GC B cells, but this hexose flowed more into the pentose phosphate pathway (PPP), whose activity was important in controlling reactive oxygen (ROS) and ASC production. In modeling how glucose usage by B cells promotes the Ab response, the control of ROS appeared insufficient. Surprisingly, the combination of galactose, which mitigated ROS, with provision of mannose - an efficient precursor to glycosylation - supported robust production of and normal Ab secretion by ASC under glucose-free conditions. Collectively, the findings indicate that GC depend on normal glucose influx, especially in PC production, but reveal an unexpected metabolic flexibility in hexose requirements. KEY POINTSO_LIGlucose influx is critical for GC homeostasis, affinity maturation and the generation of Ab-secreting cells. C_LIO_LIPlasma cell development uses the Pentose Phosphate Pathway, and hexose sugars maintain redox homeostasis. C_LIO_LIPCs can develop and achieve robust Ab secretion in the absence of glucose using a combination of hexose alternatives. C_LI

immunology↗