Arid1a-dependent canonical BAF complex suppresses inflammatory programs to drive efficient germinal center B cell responses.

The mammalian Brg1/Brm-associated factor (BAF) complexes are major regulators of nucleosomal remodeling that are commonly mutated in several cancers, including germinal center (GC)-derived B cell lymphomas. However, the specific roles of different BAF complexes in GC B cell biology are not well understood. Here we show that the AT-rich interaction domain 1a (Arid1a) containing canonical BAF (cBAF) complex is required for maintenance of GCs and high-affinity antibody responses. While Arid1a-deficient B cells undergo initial activation, they fail to sustain the GC program. Arid1a establishes permissive chromatin landscapes for B cell activation and is concomitantly required to suppress inflammatory gene programs. The inflammatory signatures instigated by Arid1a deficiency promoted the recruitment of neutrophils and inflammatory monocytes. Dampening of inflammatory cues through interleukin-1ß blockade or glucocorticoid receptor agonist partially rescued Arid1a-deficient GCs, highlighting a critical role for inflammation in impeding GCs. Our work reveals essential functions of Arid1a-dependent cBAF in promoting efficient GC responses.

A molecular dynamics simulations study on ethylene glycol-water mixtures in mesoporous silica.

We perform molecular dynamics simulations to investigate structural and dynamical properties of ethylene glycol-water (EG-WA) mixtures in mesoporous silica. To obtain comprehensive insights into the dependence of liquid behaviors on the confinement features, we exploit that straightforward modification of the force field parameters allows us to vary the properties of the hydrogen-bond network of the confined liquid, we alter the polarity of the silica surface, and we consider amorphous as well as crystalline matrices. It is observed that the confinement induces a micro-phase separation in the liquid, which qualitatively depends on the properties of both liquid and matrix so that EG or WA molecules may be preferentially adsorbed at the silica surface. Furthermore, it is found that the confinement strongly affects the liquid dynamics. Largely independent of the polarity and structure of the matrix, structural relaxation is about a factor of 10(4) slower at the pore wall than in the pore center. Moreover, the non-Arrhenius temperature dependence of the bulk mixture turns into an Arrhenius behavior of the confined mixture so that the spatial restriction can slow down or speed up the structural relaxation, depending on temperature.

Autofluorescence lifetime imaging classifies human lymphocyte activation and subtype.

New non-destructive tools are needed to reliably assess lymphocyte function for immune profiling and adoptive cell therapy. Optical metabolic imaging (OMI) is a label-free method that measures the autofluorescence intensity and lifetime of metabolic cofactors NAD(P)H and FAD to quantify metabolism at a single-cell level. Here, we investigate whether OMI can resolve metabolic changes between human quiescent versus IL4/CD40 activated B cells and IL12/IL15/IL18 activated memory-like NK cells. We found that quiescent B and NK cells were more oxidized compared to activated cells. Additionally, the NAD(P)H mean fluorescence lifetime decreased and the fraction of unbound NAD(P)H increased in the activated B and NK cells compared to quiescent cells. Machine learning classified B cells and NK cells according to activation state (CD69+) based on OMI parameters with up to 93.4% and 92.6% accuracy, respectively. Leveraging our previously published OMI data from activated and quiescent T cells, we found that the NAD(P)H mean fluorescence lifetime increased in NK cells compared to T cells, and further increased in B cells compared to NK cells. Random forest models based on OMI classified lymphocytes according to subtype (B, NK, T cell) with 97.8% accuracy, and according to activation state (quiescent or activated) and subtype (B, NK, T cell) with 90.0% accuracy. Our results show that autofluorescence lifetime imaging can accurately assess lymphocyte activation and subtype in a label-free, non-destructive manner.

Microphysiological model reveals the promise of memory-like natural killer cell immunotherapy for HIV± cancer.

Numerous studies are exploring the use of cell adoptive therapies to treat hematological malignancies as well as solid tumors. However, there are numerous factors that dampen the immune response, including viruses like human immunodeficiency virus. In this study, we leverage human-derived microphysiological models to reverse-engineer the HIV-immune system interaction and evaluate the potential of memory-like natural killer cells for HIV+ head and neck cancer, one of the most common tumors in patients living with human immunodeficiency virus. Here, we evaluate multiple aspects of the memory-like natural killer cell response in human-derived bioengineered environments, including immune cell extravasation, tumor penetration, tumor killing, T cell dependence, virus suppression, and compatibility with retroviral medication. Overall, these results suggest that memory-like natural killer cells are capable of operating without T cell assistance and could simultaneously destroy head and neck cancer cells as well as reduce viral latency.

Extracellular pH affects the fluorescence lifetimes of metabolic co-factors.

SIGNIFICANCE: Autofluorescence measurements of the metabolic cofactors NADH and flavin adenine dinucleotide (FAD) provide a label-free method to quantify cellular metabolism. However, the effect of extracellular pH on flavin lifetimes is currently unknown. AIM: To quantify the relationship between extracellular pH and the fluorescence lifetimes of FAD, flavin mononucleotide (FMN), and reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]. APPROACH: Human breast cancer (BT474) and HeLa cells were placed in pH-adjusted media. Images of an intracellular pH indicator or endogenous fluorescence were acquired using two-photon fluorescence lifetime imaging. Fluorescence lifetimes of FAD and FMN in solutions were quantified over the same pH range. RESULTS: The relationship between intracellular and extracellular pH was linear in both cell lines. Between extracellular pH 4 to 9, FAD mean lifetimes increased with increasing pH. NAD(P)H mean lifetimes decreased with increasing pH between extracellular pH 5 to 9. The relationship between NAD(P)H lifetime and extracellular pH differed between the two cell lines. Fluorescence lifetimes of FAD, FAD-cholesterol oxidase, and FMN solutions decreased, showed no trend, and showed no trend, respectively, with increasing pH. CONCLUSIONS: Changes in endogenous fluorescence lifetimes with extracellular pH are mostly due to indirect changes within the cell rather than direct pH quenching of the endogenous molecules.