Cardiorespiratory alterations following intermittent photostimulation of RVLM C1 neurons: Implications for long-term blood pressure, breathing and sleep regulation in freely moving rats

Sleep deprivation-induced sympathetic activation promotes pro-tumoral macrophage phenotype via the ADRB2/KLF4 pathway to facilitate NSCLC metastasis

Sleep deprivation is one of concomitant symptoms of cancer patients, particularly those with non-small cell lung cancer (NSCLC). The potential effect of sleep deprivation on tumor progression and underlying mechanisms remain to be fully investigated. Using a sleep-deprived tumor-bearing mouse model, we found that sleep deprivation altered immune cell composition and regulated pro-tumoral M2 macrophage polarization by the sympathetic nervous system. Furthermore, we identified a role of catecholaminergic neurons in the rostral ventrolateral medulla (RVLM) in influencing NSCLC metastasis. Clinical analyses revealed a correlation between sympathetic-related indicators and poor prognosis. Mechanistically, our findings indicate that sleep deprivation facilitates the polarization of pro-tumoral macrophages by upregulating β2-adrenergic receptor (ADRB2), which subsequently enhances the expression of Kruppel-like transcription factor 4 (KLF4) through the JAK1/STAT6 phosphorylation pathway. These findings highlight a neuro-immune mechanism linking sleep deprivation to NSCLC metastasis, suggesting that targeting the ADRB2/KLF4 axis could improve outcomes for sleep-deprived NSCLC patients.

Brainstem C1 neurons mediate heart failure decompensation and mortality during acute salt loading

AIMS

Heart failure (HF) is an emerging epidemic worldwide. Despite advances in treatment, the morbidity and mortality rate of HF remain high, and the global prevalence continues to rise. Common clinical features of HF include cardiac sympathoexcitation, disordered breathing, and kidney dysfunction; kidney dysfunction strongly contributes to sodium retention and fluid overload, leading to poor outcomes of HF patients. We have previously shown that brainstem pre-sympathetic neurons (C1) from the rostral ventrolateral medulla (RVLM) play a key role in sympathetic regulation in experimental models of HF. However, the role of RVLM-C1 neurons during salt-loading in the context of HF is unknown. This study tests whether RVLM C1 neurons drive cardiorespiratory decompensation and ultimately lead to sudden death in HF rats.

METHODS AND RESULTS

Adult male Sprague-Dawley rats underwent arteriovenous shunt to induce HF with preserved ejection fraction (HFpEF). Two weeks after HFpEF induction, bilateral selective ablation of RVLM C1 neurons was performed using anti-dopamine β-hydroxylase-saporin toxin. Animals were then fed a high Na+ diet (3% Na+ in food and 2% Na+ in water) for 3 weeks to induce compensated-to-decompensated HF state transition. Echocardiography, cardiac autonomic function, breathing function, and survival were assessed during the progression of HF. Salt loading resulted in marked decompensation in HF rats, as evidenced by a significant decrease in survival rates (survival: 10% vs. 100% HFpEF + Na+ vs. HFpEF). Furthermore, HFpEF + Na+ animals showed a further increase in cardiac sympathetic drive and more severe disordered breathing, including higher hypoxia-related epochs (i.e. apnoeas/hypopnoeas), compared with HF. Ablation of RVLM C1 neurons partly reduced the excessive cardiac sympathoexcitation during salt loading in HF, improved the exaggerated disordered breathing in HFpEF+ Na+ rats, and reduced decompensation-linked mortality. We found that hypoxia, but not high sodium, was the major contributor to impaired calcium handling in isolated adult cardiomyocytes.

CONCLUSION

Our results strongly suggest that RVLM C1 neurons contribute to acute HF decompensation during salt loading by a mechanism encompassing further increases in sympathetic outflow and hypoxia-related breathing disorders. This mechanism may ultimately impact cardiac contractility through cardiomyocyte calcium mishandling, increasing morbidity and mortality.

Peripheral chemoreceptor, a new player in metabolic sensing during physical exertion: a hypothetical scenario

The cardiorespiratory and metabolic response to exercise has been associated with meeting the organism's metabolic demands during physical exertion. Of note, an incremental exercise is characterized by 1) cardiodynamic phase related to cardiac output enhancement mainly determined by a positive chronotropic response, 2) ventilatory threshold one, associated with a significant contribution of cardiovascular and pulmonary ventilation, and 3) ventilatory threshold two, correlated with a tremendous increase in breathing and metabolic responses to exercise. Notably, it has been shown that the ventilatory response to exercise increases concomitantly with the release and accumulation of metabolites (i.e., lactate released from skeletal muscle). The principal peripheral chemoreceptors are the carotid bodies (CBs), allocated into the carotid bifurcation and demonstrated to respond to several stimuli, triggering autonomic and ventilatory responses. Indeed, in past and recent years, it has been shown that CB could respond to lactate in in vitro and in vivo preparations, eliciting an increase in CB activity and ventilation. However, not all evidence indicates that peripheral chemoreceptors respond to lactate. Thus, considering that CB chemoreceptors' role in lactate-dependent breathing response is not completely clear and their potential preponderance as metabolic sensors during exercise has not been thoroughly explored, the present review was focused on the possible role of CB chemoreceptors as metabolic sensors during physical exertion in a physiological context, proposing it as a new actor in exercise physiology.

The effects of laser acupuncture dosage at PC6 (Neiguan) on brain reactivity: a pilot resting-state fMRI study

Previous studies indicated that laser acupuncture (LA) may effectively treat various medical conditions. However, brain responses associated with LA intervention have not been fully investigated. This study is focused on the effect of LA with different energy density (ED) in brain using resting-state functional magnetic resonance imaging (fMRI). We hypothesized that different ED would elicit various brain responses. We enrolled healthy adults participants and selected bilateral PC6 (Neiguan) as the intervention points. LA was applied, respectively, with ED of 0, 7.96, or 23.87 J/cm2. Two 500-s resting-state fMRI scans were acquired before and after intervention, respectively. The functional connectivity (FC) was calculated between autonomic nerve system-regulation associated brainstem structures and other brain regions. Compared to other dosages, the FC between rostral ventrolateral medulla and orbitofrontal cortex has more enhanced; the FC between caudal ventrolateral medulla, nucleus of the solitary tract/nucleus ambiguus, and dorsal motor nucleus of the vagus and somatosensory area has more weakened when ED was 23.87 J/cm2. Different dosages of LA have demonstrated varied regions of FC changes between regions of interest and other brain areas, which indicated that variations in EDs might influence the clinical efficacy and subsequent impacts through distinct neural pathways within the brain.

A narrative review of the mechanisms and consequences of intermittent hypoxia and the role of advanced analytic techniques in pediatric autonomic disorders

Disorders of autonomic functions are typically characterized by disturbances in multiple organ systems. These disturbances are often comorbidities of common and rare diseases, such as epilepsy, sleep apnea, Rett syndrome, congenital heart disease or mitochondrial diseases. Characteristic of many autonomic disorders is the association with intermittent hypoxia and oxidative stress, which can cause or exaggerate a variety of other autonomic dysfunctions, making the treatment and management of these syndromes very complex. In this review we discuss the cellular mechanisms by which intermittent hypoxia can trigger a cascade of molecular, cellular and network events that result in the dysregulation of multiple organ systems. We also describe the importance of computational approaches, artificial intelligence and the analysis of big data to better characterize and recognize the interconnectedness of the various autonomic and non-autonomic symptoms. These techniques can lead to a better understanding of the progression of autonomic disorders, ultimately resulting in better care and management.