Background: Cigarette smoking (CS) is the leading cause of chronic obstructive pulmonary disease (COPD). The “spill-over” of pulmonary inflammation into the systemic circulation may damage the brain, leading to cognitive dysfunction. Cessation of CS can improve pulmonary and neurocognitive outcomes, however, its benefit on the neuroinflammatory profile remains uncertain. Here, we investigate how CS exposure impairs neurocognition and whether this can be reversed with CS cessation or an antioxidant treatment. Methods: Male BALB/c mice were exposed to CS (9 cigarettes/day for 8 weeks) followed by 4 weeks of CS cessation. Another cohort of CS-exposed mice were co-administrated with a glutathione peroxidase mimetic, ebselen (10 mg/kg) or vehicle (5% CM-cellulose). We assessed pulmonary inflammation, spatial and working memory, and the hippocampal microglial, oxidative and synaptic profiles. Results: CS exposure increased lung inflammation which was reduced following CS cessation. CS caused spatial and working memory impairments which were attributed to hippocampal microglial activation and suppression of synaptophysin. CS cessation did not improve memory deficits or alter microglial activation. Ebselen completely prevented the CS-induced working and spatial memory impairments, which was associated with restored synaptophysin expression without altering microglial activation. Conclusion: We were able to model the CS-induced memory impairment and microglial activation seen in human COPD. The preventative effects of ebselen on memory impairment is likely to be dependent on a preserved synaptogenic profile. Cessation alone also appears to be insufficient in correcting the memory impairment, suggesting the importance of incorporating antioxidant therapy to help maximising the benefit of cessation.

Background and Purpose: Skeletal muscle dysfunction is a major comorbidity of chronic obstructive pulmonary disease (COPD). This type of muscle dysfunction may be a direct consequence of oxidative insults evoked by cigarette smoke (CS) exposure. The present study examined the effects of a potent Nox inhibitor and reactive oxygen species (ROS) scavenger, apocynin, on CS‐induced muscle dysfunction.Experimental Approach: Male BALB/c mice were exposed to either room air (sham) or CS generated from nine cigarettes per day, 5 days a week for 8 weeks, with or without the coadministration of apocynin (5 mg·kg⁻¹, i.p.). C2C12 myotubes exposed to either hydrogen peroxide (H₂O₂) or water‐soluble cigarette smoke extract (CSE) with or without apocynin (500 nM) were used as an experimental model in vitro.Key Results: Eight weeks of CS exposure caused muscle dysfunction in mice, reflected by 10% loss of muscle mass and 54% loss of strength of tibialis anterior which were prevented by apocynin administration. In C2C12 myotubes, direct exposure to H₂O₂ or CSE caused myofibre wasting, accompanied by ~50% loss of muscle‐derived insulin‐like growth factor (IGF)‐1 and two‐fold induction of Cybb, independent of cellular inflammation. Expression of myostatin and MAFbx, negative regulators of muscle mass, were up‐regulated under H₂O₂ but not CSE conditions. Apocynin treatment abolished CSE‐induced Cybb expression, preserving muscle‐derived IGF‐1 expression and signalling pathway downstream of mammalian target of rapamycin (mTOR), thereby preventing myofibre wasting.Conclusion and Implications: Targeted pharmacological inhibition of Nox‐derived ROS may alleviate the lung and systemic manifestations in smokers with COPD.

People with COPD are susceptible to respiratory infections which exacerbate pulmonary and/or cardiovascular complications, increasing their likelihood of death. The mechanisms driving these complications remain unknown but increased oxidative stress has been implicated. Here we investigated whether influenza A virus (IAV) infection, following chronic cigarette smoke (CS) exposure, worsens vascular function and if so, whether the antioxidant ebselen alleviates this vascular dysfunction. Male BALB/c mice were exposed to either room air or CS for 8 weeks followed by inoculation with IAV (Mem71, 1 x 10^4.5 pfu)). Mice were treated with ebselen (10 mg/kg) or vehicle (5% w/v CM-cellulose in water) daily. Mice were culled 3- and 10-days post-infection, and their lungs lavaged to assess inflammation. The thoracic aorta was excised to investigate endothelial and smooth muscle dilator responses, expression of key vasodilatory and oxidative stress modulators, infiltrating immune cells and vascular remodeling. CS increased lung inflammation and caused significant vascular endothelial dysfunction, which was worsened by IAV infection. CS-driven increases in vascular oxidative stress, aortic wall remodelling and supression of eNOS were not affected by IAV infection. CS and IAV infection significantly enhanced T-cell recruitment into the aortic wall. Ebselen abolished the exaggerated lung inflammation, vascular dysfunction and increased T-cell infiltration in CS and IAV-infected mice. Our findings showed that ebselen treatment abolished vascular dysfunction in IAV-induced exacerbations of cigarette smoke-induced lung inflammation indicating it may have potential for the treatment of cardiovascular comorbidities seen in acute exacerbations of COPD.

Individuals with autism often experience gastrointestinal issues but the cause is unknown. Many gene mutations that modify neuronal synapse function are associated with autism and therefore may impact the enteric nervous system that regulates gastrointestinal function. A missense mutation in the Nlgn3 gene encoding the cell adhesion protein Neuroligin-3 was identified in two brothers with autism who both experienced severe gastrointestinal dysfunction. Mice expressing this mutation (Nlgn3^R451C mice) are a well-studied preclinical model of autism and show autism-relevant characteristics, including impaired social interaction and communication, as well as repetitive behaviour. We previously showed colonic dysmotility in response to GABAergic inhibition and increased myenteric neuronal numbers in the small intestine in Nlgn3^R451C mice bred on a mixed genetic background. Here, we show that gut dysfunction is a persistent phenotype of the Nlgn3 R451C mutation in mice backcrossed onto a C57BL/6 background. We report that Nlgn3^R451C mice show a 30.9% faster gastrointestinal transit (p = 0.0004) in vivo and have 6% longer small intestines (p = 0.04) compared to wild-types due to a reduction in smooth muscle tone. In Nlgn3^R451C mice, we observed a decrease in resting jejunal diameter (proximal jejunum: 10.6% decrease, p = 0.02; mid: 9.8%, p = 0.04; distal: 11.5%, p = 0.009) and neurally regulated dysmotility as well as shorter durations of contractile complexes (mid: 25.6% reduction in duration, p = 0.009; distal: 30.5%, p = 0.004) in the ileum. In Nlgn3^R451C mouse colons, short contractions were inhibited to a greater extent (57.2% by the GABA_A antagonist, gabazine, compared to 40.6% in wild-type mice (p = 0.007). The inhibition of nitric oxide synthesis decreased the frequency of contractile complexes in the jejunum (WT p = 0.0006, Nlgn3^R451C p = 0.002), but not the ileum, in both wild-type and Nlgn3^R451C mice. These findings demonstrate that changes in enteric nervous system function contribute to gastrointestinal dysmotility in mice expressing the autism-associated R451C missense mutation in the Neuroligin-3 protein.

Chronic obstructive pulmonary disease (COPD) is a systemic condition with significant extrapulmonary comorbidities. White adipose tissue (WAT) dysfunction, driven by cigarette smoke (CS) exposure, may contribute to systemic inflammation and disease progression. This study investigates whether oxidative stress mediates lung–adipose tissue cross-talk in COPD and whether targeting this pathway can mitigate both pulmonary and metabolic dysfunction. Male BALB/c mice were exposed to CS for 8 or 24 weeks, with or without apocynin, an NADPH oxidase inhibitor. Lung and WAT tissues were analysed for inflammation, oxidative stress, adipokine expression, and mitochondrial function. Phosphoproteomic profiling was performed on lung tissue. In vitro, conditioned media from CS-exposed bronchial epithelial cells and oxidatively primed adipocytes were used to assess reciprocal effects on adipocytes and epithelial cells. CS exposure induced airway inflammation, glucose intolerance, dyslipidaemia, and WAT dysfunction, including increased lipolysis, oxidative stress, and adipokine imbalance. Apocynin treatment reduced oxidative stress, normalised adipokine profiles, and restored mitochondrial markers in WAT. Phosphoproteomic analysis revealed activation of MAPK, TNF, and Apelin signalling pathways in the lungs. Conditioned media experiments confirmed bidirectional cross-talk: epithelial-derived factors impaired adipocyte function, while dysfunctional adipocytes triggered oxidative stress and apoptosis in bronchial epithelial cells.CS-induced oxidative stress drives a pathological feedback loop between the lungs and WAT, contributing to COPD progression and systemic metabolic dysfunction. Targeting redox-sensitive pathways may offer therapeutic strategies to disrupt this lung-adipose axis and improve outcomes in COPD.

Individuals with autism often experience gastrointestinal issues but the cause is unknown. Many gene mutations that modify neuronal synapse function are associated with autism and therefore may impact the enteric nervous system that regulates gastrointestinal function. A missense mutation in the Nlgn3 gene encoding the cell adhesion protein, Neuroligin-3, was identified in two brothers with autism who both experienced severe gastrointestinal dysfunction. Mice expressing this mutation (Nlgn3R451C mice) are a well-studied preclinical model of autism and show autism-relevant characteristics, including impaired social interaction and communication, as well as repetitive behaviour. We previously showed colonic dysmotility in response to GABAergic inhibition and increased myenteric neuronal numbers in the small intestine in Nlgn3R451C mice bred on a mixed genetic background. Here we show that gut dysfunction is a persistent phenotype of the Nlgn3 R451C mutation in mice backcrossed onto a C57BL/6 background. We report that Nlgn3R451C mice show faster gastrointestinal transit in vivo and have longer small intestines compared to wild-types due to a reduction in smooth muscle tone. In Nlgn3R451C mice, we observed a decrease in resting jejunal diameter and neurally-regulated dysmotility as well as shorter durations of contractile complexes in the ileum. In Nlgn3R451C mouse colons, short contractions were inhibited to a greater extent by the GABAA antagonist, gabazine, compared to wild-type mice. Inhibition of nitric oxide synthesis decreased the frequency of contractile complexes in the jejunum, but not the ileum, in both wild-type and Nlgn3R451C mice. These findings demonstrate that changes in enteric nervous system function contribute to gastrointestinal dysmotility in mice expressing the autism-associated R451C missense mutation in the Neuroligin-3 protein.