Wick, M. | bioRxiv Science

bioRxiv2026

Preserved Type 2 Immune Cell Plasticity in Human Obesity and Differential Immune Reconstitution After Bariatric Surgery

BackgroundObesity disrupts type 2 immune cell populations in white adipose tissue, replacing the homeostatic network of group 2 innate lymphoid cells (ILC2s), eosinophils, T helper 2 (Th2) cells, and alternatively activated macrophages (AAMs) with pro-inflammatory type 1 populations. Whether this remodelling reflects permanent immune impairment or a reversible shift in cellular equilibrium, and to what extent bariatric surgery restores type 2 immunity, remain incompletely understood. MethodsWe performed comprehensive immunophenotyping of visceral white adipose tissue (WAT) and peripheral blood from persons with severe obesity (people with obesity, PWO) scheduled for or having undergone bariatric surgery (sleeve gastrectomy, gastric bypass), combined with lean controls. Using flow cytometry, quantitative PCR, and in vitro polarization assays, we assessed immune cell frequencies, transcription factor expression, cytokine profiles, and functional polarization capacity across lean, pre-operative, and post-operative states. ResultsObesity was associated with decreased eosinophil and CD8+ T cells frequencies in WAT, accompanied by an increase in CD4+ frequency and a shift from Th2 toward Th1 predominance, as well as elevated PD-1 expression on T cell subsets. Bariatric surgery partially normalised peripheral immune cell composition, reducing CD8+ T cell frequencies while increasing CD4+ T cells. Macrophage polarization capacity, dampened in pre-operative PWO, recovered after surgery. Conversely, Th2 polarization capacity and IL-13 production were reduced in post-operative T cells despite preserved function pre-operatively, indicating divergent trajectories of innate and adaptive immune reconstitution. ConclusionType 2 immune cells retain functional plasticity in human obesity despite reduced frequency. Bariatric surgery differentially reconstitutes immune function, restoring macrophage plasticity while paradoxically reducing Th2 polarization capacity, arguing against uniform immune normalisation after weight loss. FundingGerman Federal Ministry of Research, Technology and Space (BMFTR, FKZ 01KI2109), Interdisciplinary Center for Clinical Research (IZKF, Faculty of Medicine, Friedrich-Alexander Universitat (FAU) Erlangen-Nurnberg).

immunology↗

bioRxiv2024

An improved method for sampling and quantitative protein analytics of cerebrospinal fluid of single mice

Mice are the most commonly used preclinical animal model, but protein analytics of murine cerebrospinal fluid (CSF) remains challenging because of low CSF volume (often <10 {micro}l) and frequent blood contaminations. We developed an improved CSF sampling method that allows routine collection of increased volumes (20-30 {micro}l) of pure CSF from individual mice, enabling multiple protein analytical assays from a single sample. Based on cell counts and hemoglobin ELISAs, we provide an easy quality control workflow for obtaining cell- and blood-free murine CSF. Through mass spectrometry-based proteomics using an absolutely quantified external standard, we estimated concentrations for hundreds of mouse CSF proteins. While repeated CSF sampling from the same mouse was possible, it induced CSF proteome changes. Applying the improved method, we found that the mouse CSF proteome remains largely stable over time in wild-type mice, but that amyloid pathology in the 5xFAD mouse model of Alzheimers disease massively changes the CSF proteome. Neurofilament light chain and TREM2, markers of neurodegeneration and activated microglia, respectively, were strongly upregulated and validated using immunoassays. In conclusion, our refined murine CSF collection method overcomes previous limitations, allowing multiple quantitative protein analyses for applications in biomedicine.

neuroscience↗