Immune-Triggered Forms of Plasticity Across Brain Regions

Microglia signaling in health and disease - Implications in sex-specific brain development and plasticity

Microglia, the intrinsic neuroimmune cells residing in the central nervous system (CNS), exert a pivotal influence on brain development, homeostasis, and functionality, encompassing critical roles during both aging and pathological states. Recent advancements in comprehending brain plasticity and functions have spotlighted conspicuous variances between male and female brains, notably in neurogenesis, neuronal myelination, axon fasciculation, and synaptogenesis. Nevertheless, the precise impact of microglia on sex-specific brain cell plasticity, sculpting diverse neural network architectures and circuits, remains largely unexplored. This article seeks to unravel the present understanding of microglial involvement in brain development, plasticity, and function, with a specific emphasis on microglial signaling in brain sex polymorphism. Commencing with an overview of microglia in the CNS and their associated signaling cascades, we subsequently probe recent revelations regarding molecular signaling by microglia in sex-dependent brain developmental plasticity, functions, and diseases. Notably, C-X3-C motif chemokine receptor 1 (CX3CR1), triggering receptors expressed on myeloid cells 2 (TREM2), calcium (Ca2+), and apolipoprotein E (APOE) emerge as molecular candidates significantly contributing to sex-dependent brain development and plasticity. In conclusion, we address burgeoning inquiries surrounding microglia's pivotal role in the functional diversity of developing and aging brains, contemplating their potential implications for gender-tailored therapeutic strategies in neurodegenerative diseases.

Navigating the Neuroimmunomodulation Frontier: Pioneering Approaches and Promising Horizons-A Comprehensive Review

The research in neuroimmunomodulation aims to shed light on the complex relationships that exist between the immune and neurological systems and how they affect the human body. This multidisciplinary field focuses on the way immune responses are influenced by brain activity and how neural function is impacted by immunological signaling. This provides important insights into a range of medical disorders. Targeting both brain and immunological pathways, neuroimmunomodulatory approaches are used in clinical pain management to address chronic pain. Pharmacological therapies aim to modulate neuroimmune interactions and reduce inflammation. Furthermore, bioelectronic techniques like vagus nerve stimulation offer non-invasive control of these systems, while neuromodulation techniques like transcranial magnetic stimulation modify immunological and neuronal responses to reduce pain. Within the context of aging, neuroimmunomodulation analyzes the ways in which immunological and neurological alterations brought on by aging contribute to cognitive decline and neurodegenerative illnesses. Restoring neuroimmune homeostasis through strategies shows promise in reducing age-related cognitive decline. Research into mood disorders focuses on how immunological dysregulation relates to illnesses including anxiety and depression. Immune system fluctuations are increasingly recognized for their impact on brain function, leading to novel treatments that target these interactions. This review emphasizes how interdisciplinary cooperation and continuous research are necessary to better understand the complex relationship between the neurological and immune systems.

Changes in Neuroimmunological Synapses During Cerebral Ischemia

The direct interplay between the immune and nervous systems is now well established. Within the brain, these interactions take place between neurons and resident glial cells, i.e., microglia and astrocytes, or infiltrating immune cells, influenced by systemic factors. A special form of physical cell-cell interactions is the so-called "neuroimmunological (NI) synapse." There is compelling evidence that the same signaling pathways that regulate inflammatory responses to injury or ischemia also play potent roles in brain development, plasticity, and function. Proper synaptic wiring is as important during development as it is during disease states, as it is necessary for activity-dependent refinement of neuronal circuits. Since the process of forming synaptic connections in the brain is highly dynamic, with constant changes in strength and connectivity, the immune component is perfectly suited for the regulatory task as it is in constant turnover. Many cellular and molecular players in this interaction remain to be uncovered, especially in pathological states. In this review, we discuss and propose possible communication hubs between components of the adaptive and innate immune systems and the synaptic element in ischemic stroke pathology.

Unmasking the dynamics of Mycoplasma gallisepticum: deciphering HD11 macrophage polarization for innovative infection control strategies

Mycoplasma gallisepticum (MG) is a highly contagious avian respiratory pathogen characterized by rapid spread, widespread distribution, and long-term persistence of infection. Previous studies have shown that chicken macrophage HD11 cells play a critical role in the replication and immunomodulation of MG. Macrophages are multifunctional immunomodulatory cells that polarize into different functions and morphologies in response to exogenous stimuli. However, the effect of MG infection on HD11 polarization is not well understood. In this study, we observed a time-dependent increase in both the expression of the MG-related virulence protein pMGA1.2 and the copy number of MG upon MG infection. Polarization studies revealed an upregulation of M1-type marker genes in MG-infected HD11 cells, suggesting that MG mainly induces HD11 macrophages towards M1-type polarization. Furthermore, MG activated the inflammatory vesicle NLRP3 signaling pathway, and NLRP3 inhibitors affected the expression of M1 and M2 marker genes, indicating the crucial regulatory role of the NLRP3 signaling pathway in MG-induced polarization of HD11 macrophages. Our findings reveal a novel mechanism of MG infection, namely the polarization of MG-infected HD11 macrophages. This discovery suggests that altering the macrophage phenotype to inhibit MG infection may be an effective control strategy. These findings provide new perspectives on the pathogenic mechanism and control measures of MG.

A pilot study to examine the association between COX-2 rs5275 polymorphism and the response to repetitive transcranial stimulation in schizophrenia

High frequency (HF)-rTMS has been shown to improve cognitive functions in patients with schizophrenia (SCZ). This study aimed to investigate whether COX-2 rs5275 variants were associated with cognitive improvements following rTMS treatment in patients with SCZ. Forty-eight hospitalized patients with SCZ were assigned to the neuronavigation HF-rTMS group and 28 patients to the sham group over left DLPFC for 1 month. Cognitive function was evaluated using the repeatable battery for the assessment of neuropsychological status (RBANS) at weeks 0 and 4. COX-2 rs5275 polymorphism was genotyped by a technician. At baseline, C allele carriers showed better cognitive performance relative to patients with TT homozygote. Additionally, C allele carriers had greater improvement in memory from the follow-up to baseline following rTMS stimulation, while patients with the TT genotype showed no significant improvement in memory index. More importantly, we found that COX-2 rs5275 was correlated with the response to rTMS after controlling for the covariates. This study data indicate that COX-2 rs5275 was associated with improvements in immediate memory after HF-rTMS treatment in patients with SCZ. rTMS shows an effect on memory only in C allele carriers, but not in those with the TT genotype.

Investigating microglia-neuron crosstalk by characterizing microglial contamination in human and mouse patch-seq datasets

Microglia are cells with diverse roles, including the regulation of neuronal excitability. We leveraged Patch-seq to assess the presence and effects of microglia in the local microenvironment of recorded neurons. We first quantified the amounts of microglial transcripts in three Patch-seq datasets of human and mouse neocortical neurons, observing extensive contamination. Variation in microglial contamination was explained foremost by donor identity, particularly in human samples, and additionally by neuronal cell type identity in mice. Gene set enrichment analysis suggests that microglial contamination is reflective of activated microglia, and that these transcriptional signatures are distinct from those captured via single-nucleus RNA-seq. Finally, neurons with greater microglial contamination differed markedly in their electrophysiological characteristics, including lowered input resistances and more depolarized action potential thresholds. Our results generalize beyond Patch-seq to suggest that activated microglia may be widely present across brain slice preparations and contribute to neuron- and donor-related electrophysiological variability in vitro.