Biology subjects

Tynan, A.

Publications and source records attributed to Tynan, A..

6 recordsLinked to original sources

bioRxiv2026

Activation of α7 Nicotinic Acetylcholine Receptor Inhibits Neutrophil ex vivo Swarming and Pulmonary Recruitment in Inflamed Mice through an Integrin αMβ2-dependent Mechanism

Background. The cholinergic anti-inflammatory pathway regulates inflammation through vagus signaling that activates the 7 nicotinic acetylcholine receptor (7nAChR) on leukocytes. Suppression of macrophage inflammatory cytokine production through 7nAChR-mediated inhibition of NF-{kappa}B activation is considered a central mechanism of this pathway. However, the effects of cholinergic activation of 7nAChR on neutrophils remain poorly understood. Here, we investigated whether and how activation of 7nAChR in neutrophils regulates neutrophil migration, defined the underlying molecular mechanism, and evaluated its contribution to anti-inflammatory protection during endotoxemia. Results. The ex vivo swarming assays revealed that activation of 7nAChR with the selective agonists PNU-282987 and AR-R17779 significantly inhibited human and mouse neutrophil migration. The inhibitory effect of PNU-282987 was abolished in 7nAChR-deficient neutrophils, confirming receptor specificity. Mechanistically, 7nAChR activation reduced integrin M{beta}2 activation, decreased F-actin polymerization, and impaired neutrophil polarization. These effects required M{beta}2, as PNU-282987 failed to inhibit actin remodeling in M-deficient neutrophils. Modulation of M{beta}2 activation with an activating antibody (MEM48) demonstrated that 7nAChR regulates neutrophil migration by limiting excessive M{beta}2 activation and maintaining an optimal adhesive state. In vivo, adoptively transferred fluorescently labeled PNU-282987-treated neutrophils exhibited reduced recruitment to the lungs compared with vehicle-treated neutrophils during LPS-induced endotoxemia. Furthermore, neutrophil depletion markedly diminished the protective effect of PNU-282987 on survival, demonstrating that neutrophils contribute to 7nAChR-mediated protection during systemic inflammation. Conclusions. Our findings identify neutrophils as an important cellular target of the cholinergic anti-inflammatory pathway and demonstrate that 7nAChR activation limits neutrophil migration by suppressing integrin M{beta}2 activation and actin cytoskeletal remodeling. Together, these findings establish M{beta}2 as a critical downstream effector of 7nAChR signaling in neutrophils and identify regulation of integrin activation as a previously unrecognized mechanism of the cholinergic anti-inflammatory pathway.

immunology↗

bioRxiv2026

Cholinergic impairment in the dorsal motor nucleus of the vagus during experimental Alzheimer's disease

Cholinergic neurons in the dorsal motor nucleus of the vagus (DMN) in the brainstem are a key source of efferent vagus nerve fibers that regulate vital functions, including heart rate and inflammation. Whether the integrity of DMN cholinergic neurons is affected during Alzheimer's disease (AD) remains unknown. Here, in female and male mice with experimental AD (5xFAD), which exhibit age-dependent memory impairment, basal forebrain cholinergic neurodegeneration, and microglial alterations, we observe a reduction in cholinergic neuron density in the DMN at 6 and 10 months of age. Furthermore, while an important physiological function of DMN cholinergic signaling, such as suppression of heart rate, is preserved in control mice upon electrical DMN stimulation, the extent of suppression diminishes with age in both female and male 5xFAD mice. In addition, while electrical DMN stimulation lowers pro-inflammatory cytokine levels in control mice subjected to endotoxemia, this anti-inflammatory effect is diminished with age in 5xFAD mice, with females showing earlier dysfunction at 6 months. These results reveal previously unrecognized age-dependent cholinergic deficits in the DMN and disrupted brain - to - periphery vagus nerve circuits in experimental AD. These findings advance our understanding of AD mechanisms and are of interest for the development of conceptually novel therapies.

physiology↗

bioRxiv2025

The cholinergic drug galantamine ameliorates acute and subacute peripheral and brain manifestations of acute respiratory distress syndrome in mice

Acute respiratory distress syndrome (ARDS) is a life-threatening form of acute lung injury (ALI), which is a common cause of respiratory failure and high mortality in critically ill patients. Long-term mortality and brain dysfunction have been documented in ARDS patients after hospital discharge. Inflammation plays a key role in ALI/ARDS pathogenesis. Neural cholinergic signaling regulates cytokine responses and inflammation. Here, we studied the effects of galantamine, an approved cholinergic drug (for Alzheimers disease) on ALI/ARDS severity and inflammation in mice, using a clinically relevant mouse model induced by intratracheal administration of hydrochloric acid and lipopolysaccharide. Mice were treated 30 mins prior to each insult with vehicle or galantamine (4 mg/kg, i.p.). Galantamine treatment significantly decreased bronchoalveolar lavage (BAL) and serum TNF, IL-1{beta}, and IL-6 levels, as well as BAL total protein and myeloperoxidase and lung histopathology in ALI/ARDS mice. In addition, galantamine improved the functional state of mice with ALI/ARDS during a 10-day monitoring and attenuated lung injury and indices of brain inflammation at 10 days. These findings support further studies utilizing this approved cholinergic drug in therapeutic strategies for ARDS and its subacute sequelae.

physiology↗

bioRxiv2021

Using a Quadruplet Codon to Expand the Genetic Code of an Animal

Genetic code expansion in multicellular organisms is currently limited to the use of repurposed amber stop codons. Here we introduce a system for the use of quadruplet codons to direct incorporation of non-canonical amino acids in vivo in an animal, the nematode worm Caenorhabditis elegans. We develop hybrid pyrrolysyl tRNA variants to incorporate non-canonical amino acids in response to the quadruplet codon UAGA. We demonstrate the efficiency of the quadruplet decoding system by incorporating photocaged amino acids into two proteins widely used as genetic tools. We use photocaged lysine to express photocaged Cre recombinase for the optical control of gene expression and photocaged cysteine to express photo-activatable caspase for light inducible cell ablation. Our approach will facilitate the routine adoption of quadruplet decoding for genetic code expansion in eukaryotic cells and multicellular organisms.

synthetic biology↗

bioRxiv2020

Optically splitting symmetric neuron pairs in C. elegans

Synthetic strategies for optically controlling gene expression may enable the precise spatiotemporal control of genes in any combination of cells that cannot be targeted with specific promoters. We develop an efficient genetic code expansion system in C. elegans and use it to create a photo-activatable Cre recombinase. We laser-activate Cre in single neurons within a bilaterally symmetric pair to selectively switch on expression of a loxP controlled optogenetic channel in the targeted neuron. We use the system to dissect, in freely moving animals, the individual contributions of the mechanosensory neurons PLML/PLMR to the C. elegans touch response circuit, revealing distinct and synergistic roles for these neurons. We thus demonstrate how genetic code expansion and optical targeting can be combined to break the symmetry of neuron pairs and dissect behavioural outputs of individual neurons that cannot be genetically targeted.

neuroscience↗

bioRxiv2019

Antibody responses to immunization require sensory neurons

Mammals store memories in the nervous and immune systems. Sensory neurons have been implicated in enhancing neurological memory, but whether neurons participate during immunity to novel antigens is unknown. Here, mice rendered deficient in transient receptor potential vanilloid 1 (TRPV1)-expressing sensory neurons, termed "nociceptors," fail to develop competent antibody responses to KLH and hapten-NP. Moreover, selective optogenetic stimulation of TRPV1 neurons during immunization significantly enhanced antibody responses to antigens. Thus, TRPV1 nociceptors mediate antibody responses to novel antigen, and stimulating TRPV1 nociceptors enhances antibody responses during immunization. This is the first genetic and selective functional evidence that nociceptors are required during immunization to produce antigen-specific antibodies. SummaryThe first genetic and selective functional evidence showing that TRPV1-expressing nociceptors are required for competent antibody responses to novel antigen, and stimulating TRPV1 nociceptors enhances antibody responses to novel antigen.

immunology↗