Biology subjects

O'Keeffe, M.

Publications and source records attributed to O'Keeffe, M..

5 recordsLinked to original sources

bioRxiv2024

Typical development of synaptic and neuronal properties can proceed without microglia

Brain-resident macrophages, microglia, have been proposed to play an active role in synaptic refinement and maturation, influencing plasticity and circuit-level connectivity. Here we show that a variety of neurodevelopmental processes previously attributed to microglia can proceed without them. Using a genetically modified mouse which lacks microglia (Csf1r{Delta}FIRE/{Delta}FIRE) we find that intrinsic properties, synapse number and synaptic maturation are largely normal in the hippocampal CA1 region and somatosensory cortex at stages where microglia have been implicated. Seizure susceptibility and hippocampal-prefrontal cortex coherence in awake behaving animals, processes disrupted in mice deficient in microglia-enriched genes, are also normal. Similarly, eye-specific segregation of inputs into the lateral geniculate nucleus proceeds normally in the absence of microglia. Single cell/nucleus transcriptomic analyses of neurons and astrocytes did not uncover any substantial perturbation due to microglial absence. Thus, the brain possesses remarkable adaptability to execute developmental synaptic refinement, maturation and connectivity in the absence of microglia.

neuroscience↗

bioRxiv2024

A Simple and Rapid Protocol for the Isolation of Murine Bone Marrow Suitable for the Differentiation of Dendritic Cells

The generation of bone marrow-derived dendritic cells is a widely used approach in immunological research to study antigen processing and presentation as well as T cell activation responses. However, the initial step of isolating the bone marrow can be time-consuming, especially when larger numbers of precursor cells are required. Here, we assessed whether an accelerated bone marrow isolation method using centrifugation is suitable for the differentiation of FMS-like tyrosine kinase 3 ligand-driven dendritic cells. Compared to the conventional flushing method, the centrifugation-based isolation method resulted in a similar bone marrow cell yield on day 0, increased cell numbers by day 8, similar proportions of dendritic cell subsets, and consequently a higher number of type 1 conventional dendritic cells (cDC1) from the culture. Although the primary purpose of the method optimization was to improve experimental efficiency and increase the output of cDC1s, the protocol is also compatible with the differentiation of other dendritic cell subsets such as cDC2 and plasmacytoid dendritic cells, with an improved output cell count and a consistent phenotype.

immunology↗

bioRxiv2023

Type I interferon dynamics determines memory B cell epigenetic identity in chronic viral infection

Memory B cells are key providers of long-lived immunity against infectious disease, yet in chronic viral infection they do not produce effective protection. How chronic viral infection disrupts memory B cell development, and whether such changes are reversible, remains unknown. Here, we uncover type-I interferon (IFN-I) dynamics as a key determinant in shaping chronic memory B cell development. Through single-cell (sc)ATAC-sequencing and scRNA-sequencing, we identified a unique memory subset enriched for IFN-stimulated genes (ISGs) during chronic lymphocytic choriomeningitis virus infection. Blockade of IFNAR-1 early in infection transformed the chromatin landscape of chronic memory B cells, decreasing accessibility at ISG-inducing transcription factor binding motifs and inducing a phenotypic change in the dominating memory B cell subset. However, timing was critical, with memory B cells resistant to intervention after 4 weeks post-infection. Together, our research identifies a key mechanism to instruct memory B cell identity during viral infection. One Sentence Summary: IFN dynamics in chronic versus acute viral infection determines memory B cell development.

immunology↗

bioRxiv2021

In pursuit of biomarkers for predicting susceptibility to activity-based anorexia (ABA) in adolescent female rats

Anorexia nervosa (AN) has high rates of mortality and low rates of recovery, with outcomes that worsen with illness duration. Improved early intervention strategies are required and identifying risk factors that contribute to the development of AN is critical to their implementation. The development of AN often follows a pre-existing diagnosis of anxiety disorders and obsessive-compulsive disorder and substantial genetic overlap between these conditions suggest common underlying features may predict vulnerability to AN. Moreover, patients with AN have increased levels of circulating proinflammatory cytokines, which may be involved in susceptibility to pathological weight loss considering that children with immune dysfunction have a higher risk of subsequent AN diagnoses. Here, we used the activity-based anorexia (ABA) model to examine whether baseline levels of locomotion, anxiety-like behaviour, compulsive behaviour, and circulating immune markers predict the subsequent development of pathological weight loss in adolescent female rats. While none of these primary features were shown to differentiate rats that went on to be susceptible or resistant to weight loss in ABA, increased locomotion and anxiety-like behaviour were both associated with the extent of weight loss in susceptible but not resistant animals. Intriguingly, behaviour related to poor decision-making in a situation of conflict was shown to predict vulnerability to ABA. Future research using the ABA model to uncover early predictors of AN should focus on translationally relevant assays of decision-making and cognitive behaviour, dysfunction of which may not only predispose animals to ABA but may also represent an endophenotype linking anorectic, anxiety-like and compulsive behaviour.

animal behavior and cognition↗

bioRxiv2019

Migration of intestinal dendritic cell subsets upon intrinsic and extrinsic TLR3 stimulation

Initiation of adaptive immunity to particulate antigens in lymph nodes largely depends on their presentation by migratory dendritic cells (DCs). DC subsets differ in their capacity to induce specific types of immunity, allowing subset-specific DC-targeting to influence vaccination and therapy outcomes. Faithful drug design however requires exact understanding of subset-specific versus global activation mechanisms. cDC1, the subset of DCs that excel in supporting immunity towards viruses, intracellular bacteria and tumors, express uniquely high levels of the pattern recognition receptor TLR3. Using various genetic models, we show here that both the cDC1 and cDC2 subsets of cDCs are activated and migrate equally well in response to TLR3 stimulation in a cell extrinsic and TNF dependent manner, but that cDC1 show a unique requirement for type I interferon signaling. Our findings reveal common and differing pathways regulating DC subset migration, offering important insights for the design of DC-based vaccination and therapy approaches.

immunology↗