Muscarinic M1 and M2 receptor subtypes play opposite roles in LPS-induced septic shock

Germacrone alleviates okadaic acid-induced neurotoxicity in PC12 cells via M1 muscarinic receptor-mediated Galphaq (Gq)/phospholipase C beta (PLCβ)/ protein kinase C (PKC) signaling

Alzheimer’s disease (AD) is a neurodegenerative disorder with prominent individual morbidity and mortality among elderly people. Germacrone (Germ) has been reported to exert dominant protective roles in multiple human diseases, and neurological diseases are also included. The intention of this paper is to determine the impacts of Germ on okadaic acid (OA)-treated PC12 cells and confirm the hidden regulatory mechanism. First, PC12 cells were induced by OA in the absence or presence of Germ. Cell counting kit-8 assay was to monitor cell proliferation. Western blot was to test the protein levels of cholinergic muscarinic M1 receptor (CHRM1), Galphaq (Gq), phospholipase C beta (PLCβ) and protein kinase C (PKC). The levels of reactive oxygen species (ROS) and other oxidative stress markers were evaluated using corresponding kits. ELISA was used to estimate the levels of AD markers. RT-qPCR was used to examine the mRNA levels of beta-site amyloid-precursor-protein-cleaving enzyme 1 (BACE-1) and apolipoprotein E (APOE). The results uncovered that Germ enhanced the proliferation of OA-insulted PC12 cells, elevated the protein level of CHRM1 and activated the Gq/PLCβ/PKC signaling. Moreover, after OA-induced PC12 cells were administered with Germ, insufficiency of CHRM1 impeded cell proliferation, enhanced oxidative stress and neuron injury and inactivated the Gq/PLCβ/PKC signaling. Furthermore, the addition of Gq inhibitor UBO-QIC, PLCβ inhibitor U73122 or PKC inhibitor Go6983 reversed the enhanced proliferation, the reduced oxidative stress and neuron injury in OA-treated PC12 cells caused by Germ. Collectively, Germ modulated M1 muscarinic receptor-mediated Gq/PLCβ/PKC signaling, thereby alleviating OA-induced PC12 cell injury.

Orexins: A promising target to digestive cancers, inflammation, obesity and metabolism dysfunctions

Hypothalamic neuropeptides named hypocretin/orexins which were identified in 1998 regulate critical functions such as wakefulness in the central nervous system. These past 20 years had revealed that orexins/receptors system was also present in the peripheral nervous system where they participated to the regulation of multiple functions including blood pressure regulation, intestinal motility, hormone secretion, lipolyze and reproduction functions. Associated to these peripheral functions, it was found that orexins and their receptors were involved in various diseases such as acute/chronic inflammation, metabolic syndrome and cancers. The present review suggests that orexins or the orexin neural circuitry represent potential therapeutic targets for the treatment of multiple pathologies related to inflammation including intestinal bowel disease, multiple sclerosis and septic shock, obesity and digestive cancers.

Acute Lung Injury in Cholinergic-Deficient Mice Supports Anti-Inflammatory Role of α7 Nicotinic Acetylcholine Receptor

(1) Background: The lung cholinergic pathway is important for controlling pulmonary inflammation in acute lung injury, a condition that is characterized by a sudden onset and intense inflammation. This study investigated changes in the expression levels of nicotinic and muscarinic acetylcholine receptors (nAChR and mAChR) in the lung during acute lung injury. (2) Methods: acute lung injury (ALI) was induced in wild-type and cholinergic-deficient (VAChT-KD^HOM) mice using intratracheal lipopolysaccharide (LPS) instillation with or without concurrent treatment with nicotinic ligands. Bronchoalveolar lavage fluid was collected to evaluate markers of inflammation, and then the lung was removed and processed for isolation of membrane fraction and determination of acetylcholine receptors level using radioligand binding assays. (3) Results: LPS-induced increase in lung inflammatory markers (e.g., neutrophils and IL-1β) was significantly higher in VAChT-KD^HOM than wild-type mice. In contrast, LPS treatment resulted in a significant increase in lung’s α7 nicotinic receptor level in wild-type, but not in VAChT-KD^HOM mice. However, treatment with PNU 282987, a selective α7 nicotinic receptor agonist, restored VAChT-KD^HOM mice’s ability to increase α7 nicotinic receptor levels in response to LPS-induced acute lung injury and reduced lung inflammation. LPS also increased muscarinic receptors level in VAChT-KD^HOM mice, and PNU 282987 treatment reduced this response. (4) Conclusions: Our data indicate that the anti-inflammatory effects of the lung cholinergic system involve an increase in the level of α7 nicotinic receptors. Pharmacological agents that increase the expression or the function of lung α7 nicotinic receptors have potential clinical uses for treating acute lung injury.

Nerve-macrophage interactions in cardiovascular disease

The heart is highly innervated by autonomic neurons, and dynamic autonomic regulation of the heart and blood vessels is essential for animals to carry out the normal activities of life. Cardiovascular diseases, including heart failure and myocardial infarction, are often characterized in part by an imbalance in autonomic nervous system activation, with excess sympathetic and diminished parasympathetic activation. Notably, however, this is often accompanied by chronic inflammation within the cardiovascular tissues, which suggests there are interactions between autonomic dysregulation and inflammation. Recent studies have been unraveling the mechanistic links between autonomic nerves and immune cells within cardiovascular disease. The autonomic nervous system and immune system also act in concert to coordinate the actions of multiple organs that not only maintain homeostasis but also likely play key roles in disease-disease interactions, such as cardiorenal syndrome and multimorbidity. In this review, we summarize the physiological and pathological interactions between autonomic nerves and macrophages in the context of cardiovascular disease.

Hippocampal Cholinergic Neurostimulating Peptide Suppresses LPS-Induced Expression of Inflammatory Enzymes in Human Macrophages

Hippocampal cholinergic neurostimulating peptide (HCNP) is a secreted undecapeptide produced through proteolytic cleavage of its precursor protein, HCNPpp. Within hippocampal neurons, HCNP increases gene expression of choline acetyltransferase (ChAT), which catalyzes acetylcholine (ACh) synthesis, thereby modulating neural activity. HCNPpp also appears to be expressed in various immune cells. In the present study, we observed that HCNPpp is expressed in U937 human macrophage-like cells and that HCNP exposure suppresses lipopolysaccharide (LPS)-induced gene expression of ChAT. The opposite action is also seen in T lymphocytes, which suggest that HCNP appear to suppress cholinergic system in immune cells. In addition, HCNP suppresses LPS-induced gene expression of inflammatory enzymes including cyclooxygenase 2 (COX2) and inducible nitric oxide (NO) synthase (iNOS). The suppressive effect of HCNP may reflect suppression of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling activated by LPS. Thus, HCNP may have therapeutic potential as an anti-inflammatory drug.

Protective effect of anisodamine hydrobromide on lipopolysaccharide-induced acute kidney injury

Anisodamine hydrobromide (AniHBr) is a Chinese medicine used to treat septic shock. However, whether AniHBr could ameliorate septic acute kidney injury and the underlying mechanism were not investigated. In the present study, 18 male Sprague-Dawley rats (200–250 g) were randomly divided into control, lipopolysaccharide (LPS) and LPS+AniHBr groups. Rats were intravenously administrated with LPS or normal saline (for control). After 4 h, the rats were intravenously administrated with AniHBr (LPS+AniHBr) or normal saline at 4 h intervals. Hemodynamic parameters including blood pressure and heart rate were measured. The histopathologic evaluation of kidney tissues was performed. Lactate, creatine kinase, inflammatory cytokines and oxidative stress indicators were determined. Using Seahorse analysis, the metabolic analysis of mitochondrial stress and glycolytic stress in human renal proximal tubular epithelial cells treated with TNF-α in the presence of AniHBr was performed. AniHBr administration significantly reduced serum creatine kinase and lactate following LPS treatment. AniHBr significantly improved hemodynamics in sepsis rats including increase in the mean atrial pressure and reduction in the heart rate. AniHBr significantly attenuated LPS-induced TNF-α, IL-6 and IL-1β in serum, and LPS-induced TNF-α and IL-1β in renal tissues. The LPS-reduced SOD activity and LPS-increased MDA content were reversed by AniHBr. In vitro, TNF-α increased mitochondrial oxygen consumption and glycolysis, but inhibited the ATP generation, which was reversed by AniHBr. Thus, AniHBr protects against the LPS-induced inflammatory cytokines, mitochondrial dysfunction and oxidative stress, and thus attenuates the LPS-induced acute kidney injury, showing AniHBr is a promising therapeutic drug for septic kidney injury.

Sexual dimorphism in immunometabolism and autoimmunity: Impact on personalized medicine

Immune cells play essential roles in metabolic homeostasis and thus, undergo analogous changes in normal physiology (e.g., puberty and pregnancy) and in various metabolic and immune diseases. An essential component of this close relationship between the two is sex differences. Many autoimmune diseases, such as systemic lupus erythematous and multiple sclerosis, feature strikingly increased prevalence in females, whereas in contrast, infectious diseases, such as Ebola and Middle East Respiratory Syndrome, affect more men than women. Therefore, there are fundamental aspects of metabolic homeostasis and immune functions that are regulated differently in males and females. This can be observed in sex hormone-immune interaction where androgens, such as testosterone, have shown immunosuppressive effects whilst estrogen is on the opposite side of the spectrum with immunoenhancing facilitation of mechanisms. In addition, the two sexes exhibit significant differences in metabolic regulation, with estrous cycles in females known to induce variability in traits and more pronounced metabolic disease phenotype exhibited by males. It is likely that these differences underlie both the development of metabolic and autoimmune diseases and the response to current treatment options. Sexual dimorphism in immunometabolism has emerged to become an area of intense research, aiming to uncover sex-biased effector molecules in the various metabolic tissues and immune cell types, identify sex-biased cell-type-specific functions of common effector molecules, and understand whether the sex differences in metabolic and immune functions influence each other during autoimmune pathogenesis. In this review, we will summarize recent findings that address these critical questions of sexual dimorphism in immunometabolism as well as their translational implications for the clinical management of autoimmune diseases.

Interleukin-5 deletion promotes sepsis-induced M1 macrophage differentiation, deteriorates cardiac dysfunction, and exacerbates cardiac injury via the NF-κB p65 pathway in mice

Inflammation plays a crucial role in sepsis-induced cardiac injury. The purpose of this study was to determine whether interleukin-5 (IL-5) affected lipopolysaccharide (LPS)-induced cardiac injury by regulating the inflammatory response. First, the expression level and source of cardiac IL-5 were examined, and the results showed that LPS treatment and cecal ligation decreased cardiac IL-5 expression in macrophages. In addition, LPS was used to establish a mouse sepsis model, and the effects of IL-5 deletion on cardiac injury, M1 macrophage differentiation and myocardial cell apoptosis were analyzed. The results showed that IL-5 deficiency significantly increased cardiac injury marker expression, worsened cardiac dysfunction, promoted M1 macrophage differentiation and exacerbated myocardial cell apoptosis in LPS-induced septic mice. The nuclear factor-kappa B (NF-κB) p65 pathway was inhibited by JSH-23, and the results showed that treatment with JSH-23 inhibited M1 macrophage differentiation and alleviated cardiac injury in LPS-treated IL-5-knockout mice. Furthermore, the effects of IL-5 deficiency on M1 macrophage differentiation and myocardial cell apoptosis were measured in vitro. The IL-5-mediated promotion of M1 macrophage differentiation was also reversed by S31-201, and the pro-apoptotic effect of IL-5 knockout on macrophage-mediated myocardial cell apoptosis was also reversed by JSH-23. In conclusion, we found that IL-5 knockout may exacerbate sepsis-induced cardiac injury by promoting M1 macrophage differentiation in mice. IL-5 may be a potential target for the clinical prevention of sepsis-related cardiac injury.