Macrophage beta2-adrenergic receptor is dispensable for the adipose tissue inflammation and function

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.

Metabolic phenotypes in a Lyz2Cre recombinase mouse model

The Cre-Lox system is essential in biomedical research for precise gene deletion in specific cell types, crucial for understanding genetic roles in disease. Although generally considered non-detrimental, Cre recombinase expression has been associated with potential adverse effects, including Cre toxicity, ectopic expression, and disruption of endogenous genes. We investigated the role of macrophage nucleotide-binding oligomerization domain (Nod1) in obesity-associated diabetes using myeloid-specific Nod1-knockout mice (Nod1 floxed crossed with Lyz2Cre). Our study examined Lyz2Cre as well as floxed control mice separately, unlike most research. Results indicated that Lyz2Cre expression alone impacts glucose metabolism, challenging the notion that Cre expression is harmless. This finding highlights the critical importance of including Cre-only controls in studies using floxed alleles to generate conditional knockout mouse models in order to ensure robust and accurate conclusions in molecular research.

Interplay between the brain and adipose tissue: a metabolic conversation

The central nervous system and adipose tissue interact through complex communication. This bidirectional signaling regulates metabolic functions. The hypothalamus, a key homeostatic brain region, integrates exteroceptive and interoceptive signals to control appetite, energy expenditure, glucose, and lipid metabolism. This regulation is partly achieved via the nervous modulation of white (WAT) and brown (BAT) adipose tissue. In this review, we highlight the roles of sympathetic and parasympathetic innervation in regulating WAT and BAT activities, such as lipolysis and thermogenesis. Adipose tissue, in turn, plays a dual role as an energy reservoir and an endocrine organ, secreting hormones that influence brain function and metabolic health. In addition, this review focuses on recently uncovered communication pathways, including extracellular vesicles and neuro-mesenchymal units, which add new layers of regulation and complexity to the brain-adipose tissue interaction. Finally, we also examine the consequences of disrupted communication between the brain and adipose tissue in metabolic disorders like obesity and type-2 diabetes, emphasizing the potential for new therapeutic strategies targeting these pathways to improve metabolic health.

ADRB2 serves as a novel biomarker and attenuates alcoholic hepatitis via the SIRT1/PGC-1α/PPARα pathway: integration of WGCNA, machine learning and experimental validation

Background

Alcoholic hepatitis is a severe inflammatory liver disease. In recent years, the incidence of AH has been on the rise, leading to an increasingly severe disease burden. Currently, there is a lack of specific biomarkers for the diagnosis and prognosis of AH in clinical practice. Therefore, the main objective of this study is to identify biomarkers closely associated with the progression of AH, to address the shortcomings in pathological diagnosis, and to identify potential therapeutic targets.

Methods

Bioinformatics and machine learning methods were used to comparatively study the differentially expressed genes (DEGs) between AH patients and healthy individuals by analyzing four mRNA microarray data sets obtained from the GEO database. Subsequently, the role of potential biomarkers in AH and their mechanism of action were further confirmed by AH patients and in vitro and in vivo experiments.

Results

Using differential analysis and WGCNA of the data set, a total of 167 key genes that may be related to AH were obtained. Among 167 genes, the LASSO logistic regression algorithm identified four potential biomarkers (KCNJ10, RPL21P23, ADRB2, and AC025279.1). Notably, ADRB2 showed biomarker potential in GSE28619, GSE94397, and E-MTAB-2664 datasets, and clinical liver samples. Furthermore, AH patients and in vivo experiments demonstrated ADRB2 inhibition and suppression of SIRT1/PPARα/PGC-1α signaling pathways, accompanied by elevated inflammatory factors and lipid deposition. In vitro experiments showed that ADRB2 overexpression mitigated the inhibition of the SIRT1/PPARα/PGC-1α signaling pathway, reversing the decrease in mitochondrial membrane potential, cell apoptosis, oxidative stress, and lipid deposition induced by alcohol exposure. Besides, the results also showed that ADRB2 expression in AH was negatively correlated with the levels of inflammatory factors (e.g., CCL2, CXCL8, and CXCL10).

Conclusion

This study points to ADRB2 as a promising biomarker with potential diagnostic and prognostic value in clinical cohort data. In addition, in AH patients, in vivo and in vitro experiments confirmed the key role of ADRB2 in the progression of AH. These findings suggest that ADRB2 may alleviate AH by activating the SIRT1/PPARα/PGC-1α pathway. This finding provides a new perspective for the diagnosis and treatment of AH.

Endothelial pyroptosis-driven microglial activation in choroid plexus mediates neuronal apoptosis in hemorrhagic stroke rats

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) is associated with alarmingly high rates of disability and mortality, and current therapeutic options are suboptimal. A critical component of ICH pathology is the initiation of a robust inflammatory response, often termed "cytokine storm," which amplifies the secondary brain injury following the initial hemorrhagic insult. The precise sources and consequences of this cytokine-driven inflammation are not fully elucidated, necessitating further investigation.

METHODS

To address this knowledge gap, our study conducted a comprehensive cytokine profiling using Luminex® assays, assessing 23 key cytokines. We then employed single-cell RNA sequencing and spatial transcriptomics at three critical time points post-ICH: the hyperacute, acute, and subacute phases. Integrating these multimodal analyses allowed us to identify the cellular origins of cytokines and elucidate their mechanisms of action.

RESULTS

Luminex® cytokine assays revealed a significant upregulation of IL-6 and IL-1β levels at the 24-h post-ICH time point. Through the integration of scRNA-seq and spatial transcriptomics in the hemorrhagic hemisphere of rats, we observed a pronounced activation of cytokine-related signaling pathways within the choroid plexus. Initially, immune cell presence was sparse, but it surged 24 h post-ICH, particularly in the choroid plexus, indicating a substantial shift in the immune microenvironment. We traced the source of IL-1β and IL-6 to endothelial cells, establishing a link to pyroptosis. Endothelial pyroptosis post-ICH induced the production of IL-1β and IL-6, which activated microglial polarization characterized by elevated expression of Msr1, Lcn2, and Spp1 via the NF-κB pathway in the choroid plexus. Furthermore, we identified neuronal populations undergoing apoptosis, mediated by the Lcn2-SLC22A17 pathway in response to IL-1β and IL-6 signaling. Notably, the inhibition of pyroptosis using VX-765 significantly mitigated neurological impairments.

CONCLUSIONS

Our study provides evidence that endothelial pyroptosis, characterized by the release of IL-1β and IL-6, triggers microglial polarization through NF-κB pathway activation, ultimately leading to microglia-mediated neuronal apoptosis in the choroid plexus post-ICH. These findings suggest that targeted therapeutic strategies aimed at mitigating endothelial cell pyroptosis and neutralizing inflammatory cytokines may offer neuroprotection for both microglia and neurons, presenting a promising avenue for ICH treatment.

Hypotensive drugs mitigate the high-sodium diet-induced pro-inflammatory activation of mouse macrophages in vivo

Nowadays, there is an increasing emphasis on the need to alleviate the chronic inflammatory response to effectively treat hypertension. However, there are still gaps in our understanding on how to achieve this. Therefore, research on interaction of antihypertensive drugs with the immune system is extremely interesting, since their therapeutic effect could partly result from amelioration of hypertension-related inflammation, in which macrophages seem to play a pivotal role. Thus, current comprehensive studies have investigated the impact of repeatedly administered hypotensive drugs (captopril, olmesartan, propranolol, carvedilol, amlodipine, verapamil) on macrophage functions in the innate and adaptive immunity, as well as if drug-induced effects are affected by a high-sodium diet (HSD), one of the key environmental risk factors of hypertension. Although the assayed medications increased the generation of reactive oxygen and nitrogen intermediates by macrophages from standard fed donors, they reversed HSD-induced enhancing effects on macrophage oxidative burst and secretion of pro-inflammatory cytokines. On the other hand, some drugs increased macrophage phagocytic activity and the expression of surface markers involved in antigen presentation, which translated into enhanced macrophage ability to activate B cells for antibody production. Moreover, the assayed medications augmented macrophage function and the effector phase of contact hypersensitivity reaction, but suppressed the sensitization phase of cell-mediated hypersensitivity under HSD conditions. Our current findings contribute to the recognition of mechanisms, by which excessive sodium intake affects macrophage immune activity in hypertensive individuals, and provide evidence that the assayed medications mitigate most of the HSD-induced adverse effects, suggesting their additional protective therapeutic activity.

Macrophage function in adipose tissue homeostasis and metabolic inflammation

Obesity-related metabolic organ inflammation contributes to cardiometabolic disorders. In obese individuals, changes in lipid fluxes and storage elicit immune responses in the adipose tissue (AT), including expansion of immune cell populations and qualitative changes in the function of these cells. Although traditional models of metabolic inflammation posit that these immune responses disturb metabolic organ function, studies now suggest that immune cells, especially AT macrophages (ATMs), also have important adaptive functions in lipid homeostasis in states in which the metabolic function of adipocytes is taxed. Adverse consequences of AT metabolic inflammation might result from failure to maintain local lipid homeostasis and long-term effects on immune cells beyond the AT. Here we review the complex function of ATMs in AT homeostasis and metabolic inflammation. Additionally, we hypothesize that trained immunity, which involves long-term functional adaptations of myeloid cells and their bone marrow progenitors, can provide a model by which metabolic perturbations trigger chronic systemic inflammation.

Neuroimmune regulation of white adipose tissues

The white adipose tissues (WAT) are located in distinct depots throughout the body. They serve as an energy reserve, providing fatty acids for other tissues via lipolysis when needed, and function as an endocrine organ to regulate systemic metabolism. Their activities are coordinated through intercellular communications among adipocytes and other cell types such as residential and infiltrating immune cells, which are collectively under neuronal control. The adipocytes and immune subtypes including macrophages/monocytes, eosinophils, neutrophils, group 2 innate lymphoid cells (ILC2s), T and B cells, dendritic cells (DCs), and natural killer (NK) cells display cellular and functional diversity in response to the energy states and contribute to metabolic homeostasis and pathological conditions. Accumulating evidence reveals that neuronal innervations control lipid deposition and mobilization via regulating lipolysis, adipocyte size, and cellularity. Vice versa, the neuronal innervations and activity are influenced by cellular factors in the WAT. Though the literature describing adipose tissue cells is too extensive to cover in detail, we strive to highlight a selected list of neuronal and immune components in this review. The cell-to-cell communications and the perspective of neuroimmune regulation are emphasized to enlighten the potential therapeutic opportunities for treating metabolic disorders.

Reciprocal signaling between adipose tissue depots and the central nervous system

In humans, various dietary and social factors led to the development of increased brain sizes alongside large adipose tissue stores. Complex reciprocal signaling mechanisms allow for a fine-tuned interaction between the two organs to regulate energy homeostasis of the organism. As an endocrine organ, adipose tissue secretes various hormones, cytokines, and metabolites that signal energy availability to the central nervous system (CNS). Vice versa, the CNS is a critical regulator of adipose tissue function through neural networks that integrate information from the periphery and regulate sympathetic nerve outflow. This review discusses the various reciprocal signaling mechanisms in the CNS and adipose tissue to maintain organismal energy homeostasis. We are focusing on the integration of afferent signals from the periphery in neuronal populations of the mediobasal hypothalamus as well as the efferent signals from the CNS to adipose tissue and its implications for adipose tissue function. Furthermore, we are discussing central mechanisms that fine-tune the immune system in adipose tissue depots and contribute to organ homeostasis. Elucidating this complex signaling network that integrates peripheral signals to generate physiological outputs to maintain the optimal energy balance of the organism is crucial for understanding the pathophysiology of obesity and metabolic diseases such as type 2 diabetes.

Propranolol blocks osteosarcoma cell cycle progression, inhibits angiogenesis and slows xenograft growth in combination with cisplatin-based chemotherapy

Osteosarcoma is still associated with limited response to standard-of-care therapy and alarmingly elevated mortality rates, especially in low- and middle-income countries. Despite multiple efforts to repurpose β-blocker propranolol in oncology, its potential application in osteosarcoma management remains largely unexplored. Considering the unsatisfied clinical needs of this aggressive disease, we evaluated the antitumoral activity of propranolol using different in vitro and in vivo osteosarcoma preclinical models, alone or in addition to chemotherapy. Propranolol significantly impaired cellular growth in β2-adrenergic receptor-expressing MG-63 and U-2OS cells, and was capable of blocking growth-stimulating effects triggered by catecholamines. siRNA-mediated ADRB2 knockdown in MG-63 cells was associated with decreased cell survival and a significant attenuation of PPN anti-osteosarcoma activity. Direct cytostatic effects of propranolol were independent of apoptosis induction and were associated with reduced mitosis, G0/G1 cell cycle arrest and a significant down-regulation of cell cycle regulator Cyclin D1. Moreover, colony formation, 3D spheroid growth, cell chemotaxis and capillary-like tube formation were drastically impaired after propranolol treatment. Interestingly, anti-migratory activity of β-blocker was associated with altered actin cytoskeleton dynamics. In vivo, propranolol treatment (10 mg/kg/day i.p.) reduced the early angiogenic response triggered by MG-63 cells in nude mice. Synergistic effects were observed in vitro after combining propranolol with chemotherapeutic agent cisplatin. Sustained administration of propranolol (10 mg/kg/day i.p., five days a week), alone and especially in addition to low-dose metronomic cisplatin (2 mg/kg/day i.p., three times a week), markedly reduced xenograft progression. After histological analysis, propranolol and cisplatin combination resulted in low tumor mitotic index and increased tumor necrosis. β-blockade using propranolol seems to be an achievable and cost-effective therapeutic approach to modulate osteosarcoma aggressiveness. Further translational studies of propranolol repurposing in osteosarcoma are warranted.

The correlation of pericoronary adipose tissue with coronary artery disease and left ventricular function

OBJECTIVE

We sought to investigate the correlation of pericoronary adipose tissue with coronary artery disease and left ventricular (LV) function.

METHODS

Participants with clinically suspected coronary artery disease were enrolled. All participants underwent coronary computed tomography angiography (CCTA) and echocardiography followed by invasive coronary angiography (ICA) within 6 months. Pericoronary adipose tissue (PCAT) was extracted to analyze the correlation with the Gensini score and LV function parameters, including IVS, LVPW, LVEDD, LVESD, LVEDV, LVESV, FS, LVEF, LVM, and LVMI. The correlation between PCAT and the Gensini score was assessed using Spearman's correlation analysis, and that between the PCAT volume or FAI and LV function parameters was determined using partial correlation analysis.

RESULTS

One hundred and fifty-nine participants (mean age, 64.55 ± 10.64 years; men, 65.4% [104/159]) were included in the final analysis. Risk factors for coronary artery disease, such as hypertension, diabetes, dyslipidemia, and a history of smoking or drinking, had no significant association with PCAT (P > 0.05), and there was also no correlation between PCAT and the Gensini score. However, the LAD-FAI was positively correlated with the IVS (r = 0.203, P = 0.013), LVPW (r = 0.218, P = 0.008), LVEDD (r = 0.317, P < 0.001), LVESD (r = 0.298, P < 0.001), LVEDV (r = 0.317, P < 0.001), LVESV (r = 0.301, P < 0.001), LVM (r = 0.371, P < 0.001), and LVMI (r = 0.304, P < 0.001). Also, the LCX-FAI was positively correlated with the LVEDD (r = 0.199, P = 0.015), LVESD (r = 0.190, P = 0.021), LVEDV (r = 0.203, P = 0.013), LVESV (r = 0.197, P = 0.016), LVM (r = 0.220, P = 0.007), and LVMI (r = 0.172, P = 0.036), and the RCA-FAI was positively correlated with the LVEDD (r = 0.258, P = 0.002), LVESD (r = 0.238, P = 0.004), LVEDV (r = 0.266, P = 0.001), LVESV (r = 0.249, P = 0.002), LVM (r = 0.237, P = 0.004), and LVMI (r = 0.218, P = 0.008), respectively. Finally, the total volume was positively correlated with FS (r = 0.167, P = 0.042).

CONCLUSION

The FAI was positively correlated with the LV function but was not associated with the severity of coronary artery disease.

Neuroendocrine regulations in tissue-specific immunity: From mechanism to applications in tumor

Immune responses in nonlymphoid tissues play a vital role in the maintenance of homeostasis. Lots of evidence supports that tissue-specific immune cells provide defense against tumor through the localization in different tissue throughout the body, and can be regulated by diverse factors. Accordingly, the distribution of nervous tissue is also tissue-specific which is essential in the growth of corresponding organs, and the occurrence and development of tumor. Although there have been many mature perspectives on the neuroendocrine regulation in tumor microenvironment, the neuroendocrine regulation of tissue-specific immune cells has not yet been summarized. In this review, we focus on how tissue immune responses are influenced by autonomic nervous system, sensory nerves, and various neuroendocrine factors and reversely how tissue-specific immune cells communicate with neuroendocrine system through releasing different factors. Furthermore, we pay attention to the potential mechanisms of neuroendocrine-tissue specific immunity axis involved in tumors. This may provide new insights for the immunotherapy of tumors in the future.

Adrenergic Signaling Regulation Of Macrophage Function: Do We Understand It Yet?

Macrophages are immune cells that are widespread throughout the body and critical for maintaining tissue homeostasis. Their remarkable plasticity allows them to acquire different phenotypes, becoming able either to fight infection (M1-like, classically activated macrophages) or to promote tissue remodeling and repair (M2-like, alternatively activated macrophages). These phenotypes are induced by different cues present in the microenvironment. Among the factors that might regulate macrophage activation are mediators produced by different branches of the nervous system. The regulation exerted by the sympathetic nervous system (SNS) on macrophages (and the immune system in general) is becoming a subject of increasing interest, indeed a great number of articles have been published lately. Catecholamines (noradrenaline and adrenaline) activate α and β adrenergic receptors expressed by macrophages and shape the effector functions of these cells in contexts as diverse as the small intestine, the lung, or the adipose tissue. Activation of different subsets of receptors seems to produce antagonistic effects, with α adrenergic receptors generally associated with pro-inflammatory functions and β adrenergic receptors (particularly β2) related to the resolution of inflammation and tissue remodeling. However, exceptions to this paradigm have been reported, and the factors contributing to these apparently contradictory observations are still far from being completely understood. Additionally, macrophages per se seem to be sources of catecholamines, which is also a subject of some debate. In this review, we discuss how activation of adrenergic receptors modulates macrophage effector functions and its implications for inflammatory responses and tissue homeostasis.

Eosinophils regulate intra-adipose axonal plasticity

Neuronal innervation in the adipose tissues plays a crucial role in regulating adipose thermogenic capacity and metabolic homeostasis. The tissue-wide nerves display a large extent of structural plasticity under physiological and pathological conditions that alter the neuronal control of metabolic states. We find here that neuronal plasticity is regulated by immune cells, which constitutes an appealing way to reshape neural-controlled energy balance by targeting immune components.

Sympathetic innervation regulates energy balance, and the nerve density in the adipose tissues changes under various metabolic states, resulting in altered neuronal control and conferring resilience to metabolic challenges. However, the impact of the immune milieu on neuronal innervation is not known. Here, we examined the regulatory role on nerve plasticity by eosinophils and found they increased cell abundance in response to cold and produced nerve growth factor (NGF) in the white adipose tissues (WAT). Deletion of Ngf from eosinophils or depletion of eosinophils impairs cold-induced axonal outgrowth and beiging process. The spatial proximity between sympathetic nerves, IL-33–expressing stromal cells, and eosinophils was visualized in both human and mouse adipose tissues. At the cellular level, the sympathetic adrenergic signal induced calcium flux in the stromal cells and subsequent release of IL-33, which drove the up-regulation of IL-5 from group 2 innate lymphoid cells (ILC2s), leading to eosinophil accretion. We propose a feed-forward loop between sympathetic activity and type 2 immunity that coordinately enhances sympathetic innervation and promotes energy expenditure.

Fat mesenchyme closes the neural-ILC2 circuit

The immune milieu and neuronal activity each impact adipose metabolic health, yet their interplay remains largely undefined. In a recent issue of Nature, Cardoso et al. uncover a sympathetic neuro-mesenchymal-ILC2s circuit from brain-to-fat controlling obesity and glucose metabolism.