Increasing evidence indicates that hypertension and hypertensive end organ damage are not only mediated by hemodynamic injury but that inflammation plays an important role in the pathophysiology and contributes to the deleterious consequences of this disease. The complement system is an ancient part of innate immunity comprising multiple serum proteins and cellular receptors that protect the host from a hostile microbial environment and maintain tissue and cell integrity through the elimination of altered or dead cells. As an important effector arm of innate immunity, it plays also central roles in the regulation of adaptive immunity. Innate and adaptive immune responses have been identified as crucial players in the pathogenesis of arterial hypertension and hypertensive end organ damage. Thus, complement activation may drive the pathology of hypertension and hypertensive injury through its impact on innate and adaptive immune responses aside from direct effects on the vasculature. Indeed, recent experimental data strongly support a role for complement in all stages of arterial hypertension and hypertensive end organ damage. The remarkably similar clinical and histopathological features of malignant nephrosclerosis and atypical hemolytic uremic syndrome, which is driven by complement activation, suggest also a role for complement also in the development of malignant nephrosclerosis. We herein review the role of complement proteins in hypertension and hypertensive end organ damage.
Background and Purpose: Pharmacological intervention to induce white adipose tissue browning provides a promising anti-obese therapy. The fruits of Garcinia cambogia (Clusiaceae) have been widely applied to manage body weight. The current study aims to uncover the chemical principles responsible for the anti-obese property of the fruits of G. cambogia and investigate the underlying mechanisms. Experimental Approach: The bioactivity-based molecular networking and Oil-red O staining on 3T3-L1 and C3H10T1/2 adipocytes were applied for guided isolation. High-fat diet-induced obese mice were recruited to evaluate the anti-obese activity. Key Results: Guided by the bioactivity-based molecular networking, several polycyclic polyprenylated acylphloroglucinols were targetedly isolated from the fruits of G. cambogia with lipid lowering effect on adipocytes, including guttiferone J (GOJ), garcinol and 14-deoxygarcinol. As the most potent one, GOJ (10 µM) reduced lipid accumulation by 70% and 76% in 3T3-L1 and C3H10T1/2 adipocytes, respectively. Furthermore, GOJ (2.5‒10 µM) activated the deacetylase Sirtuin 3 (SIRT3), which, in turn, reduced the acetylation level of PPARγ coactivator-1α to boost mitochondrial biogenesis, and promoted uncoupling protein 1 expression and function to enhance thermogenesis, resulting in browning of adipocytes. In high-fat diet-induced-obese mice, GOJ (10 and 20 mg∙Kg-1) protected against adiposity, hyperlipidemia, insulin resistance and liver lipotoxicity, through boosting SIRT3-mediated browning of inguinal white adipose tissue. Conclusions and Implications: The bioactivity-based molecular networking is a promising strategy for guided isolation of bioactive molecules, and GOJ represents a new scaffold of thermogenic inducer, which might be responsible for the anti-obese property of G. cambogia.
Background and purpose The incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), secreted by the enteroendocrine K-cells in the proximal intestine, may regulate lipid metabolism and adiposity but its exact role in these processes is unclear. Experimental approach We characterized in vitro and in vivo antagonistic properties of a novel GIP analogue, mGIPAnt-1. We further assessed the in vivo pharmacokinetic profile of this antagonist, as well as its ability to affect high-fat diet (HFD)-induced body weight gain in ovariectomized mice during an 8-week treatment period. Key results mGIPAnt-1 showed competitive antagonistic properties to the GIP receptor (GIPR) in vitro as it inhibited GIP-induced cAMP accumulation in COS-7 cells. Furthermore, mGIPAnt-1 was capable of inhibiting GIP-induced glucoregulatory and insulinotropic effects in vivo and has a favourable pharmacokinetic profile with a half-life of 7.2 hours in C57Bl6 female mice. Finally, sub-chronic treatment with mGIPAnt-1 in ovariectomized HFD mice resulted in a reduction of body weight and fat mass. Conclusion and Implications mGIPAnt-1 successfully inhibited acute GIP-induced effects in vitro and in vivo and sub-chronically induces resistance to HFD-induced weight gain in ovariectomized mice. Our results support the development of GIP antagonists for the therapy of obesity.
Background and Purpose: New remedies are required for the treatment of diabetic neuropathic pain (DNP) due to insufficient efficacy of available therapies. Here, we used chemogenetic approaches combined with in vivo pharmacology to elucidate the role of BLA astrocytes in DNP pathogenesis and provide new insights into DNP therapeutic strategies. Experimental Approach: A streptozotocin-induced DNP model was established. Designer receptors exclusively activated by designer drugs (DREADDs) were used to regulate the activity of astrocytes. Mechanical hyperalgesia was assessed using the electronic von Frey test. Anxiety-like behaviors were detected by open field and elevated plus maze tests. Astrocytic activity was detected by immunofluorescence, and cytokine content was determined by ELISA. Key Results: BLA astrocytes were regulated by DREADDs, and inhibition of BLA astrocytes attenuated mechanical allodynia and anxiety-like behavior in DNP rats. Contrastively, temporary activation of BLA astrocytes induced allodynia without anxious behavior in naive rats. In addition, we found that koumine alleviates mechanical allodynia and anxiety-like behavior in DNP rats, inhibits the activation of BLA astrocytes and suppresses the inflammatory response. Furthermore, persistent activation of BLA astrocytes by chemogenetic mimics chronic pain, and koumine can alleviate its pain hypersensitivity and anxiety-like behavior. Conclusion and Implications: DREADDs bidirectionally regulate the activity of BLA astrocytes, which proves for the first time the role of BLA astrocytes activation in the pathogenesis of DNP and represents a novel therapeutic strategy for DNP. Koumine ameliorated DNP, perhaps by inhibiting the activation of BLA astrocytes and reveal KM as a potential candidate for treating DNP.
BACKGROUND AND PURPOSE: The α7 and α4β2* (* denotes possibly assembly with another subunit) nicotinic acetylcholine receptors (nAChR) are the most abundant nAChR in the mammalian brain. These subtypes are also the most commonly targeted nAChR in drug discovery programs for brain disorders. However, the development of subtype-specific agonists remains challenging, mainly due to the high degree of sequence homology coupled to the conservation of function in the nAChR family. Here, we determined the structural underpinning of the selectivity of 10-methylcytisine, a compound with high-affinity for α4β2* nAChR but negligible selectivity for the α7 subtype. EXPERIMENTAL APPROACH: The structural underpinning of the receptor selectivity of 10-methylcytisine was investigated using molecular dynamics simulations combined with mutagenesis and whole-cell and single-channel current recordings. KEY RESULTS: We identify a conserved arginine residue in the β3-strand that exhibits a non-conserved salt-bridge in the nAChR family. In α4β2 nAChR, the arginine forms an inter-subunit salt-bridge with an aspartate residue in loop B that is necessary for functional expression, whereas in the α7 subtype, this residue is not stabilised by electrostatic interactions, making its side chain highly mobile. This produces steric clashes with agonists and affects the dynamics of residues involved in agonist binding or the coupling network. CONCLUSIONS AND IMPLICATIONS: We conclude that the high mobility of the arginine residue in the α7 nAChR subtype affects agonist function by influencing agonist binding and the pathway communicating agonist binding to the ion channel. The findings have implications for the rational design of subtype-selective cholinergic agents.
Background and Purpose. Pseudomonas aeruginosa is a main cause of ventilator-associated pneumonia (VAP) with drug-resistant bacteria. Bacteriophage therapy has experienced resurgence to compensate for the limited development of novel antibiotics. However, phage therapy is limited to a compassionate use so far, resulting from lack of adequate studies in relevant pharmacological models. We used a pig model of VAP caused by P. aeruginosa that recapitulates essential features of human disease to study the antimicrobial efficacy of nebulized-phage therapy. Experimental Approach. (i) Lysis kinetic assays were performed to evaluate in vitro phage antibacterial efficacy against P. aeruginosa and select relevant combinations of lytic phages. (ii) The efficacy of the phage combinations was investigated in vivo (murine model of P. aeruginosa lung infection). (iii) We determined the optimal conditions to ensure efficient phage delivery by aerosol during mechanical ventilation. (iv) Lung antimicrobial efficacy of inhaled-phage therapy was evaluated in pigs, which were anesthetized, mechanically ventilated and infected with P. aeruginosa. Key Results. By selecting an active phage cocktail and optimizing aerosol delivery conditions, we were able to deliver high phage concentrations in the lungs, which resulted in a rapid and marked reduction in P. aeruginosa density (1.5 Log reduction, p<0.001). No phage was detected in the sera and urines throughout the experiment. Conclusion and Implications. Our findings demonstrated: (i) the feasibility of delivering large amounts of active phages by nebulization during mechanical ventilation, (ii) rapid control of in situ infection by inhaled bacteriophage in an experimental model of VAP with high translational value.
Background and Purpose: It is well established that both smokers and patients with COPD are at a significantly heightened risk of cardiovascular disease (CVD), although the mechanisms underpinning the onset and progression of comorbid CVD are largely unknown. Here, we explored whether cigarette smoke (CS) exposure impairs vascular function in mice and given the well-known pathological role for oxidative stress in COPD, whether the antioxidant compound ebselen prevents CS-induced vascular dysfunction in mice. Experimental Approach: Male BALB/c mice were exposed to either room air (sham) or CS generated from 9 cigarettes per day, 5 days a week for 8 weeks. Mice were treated with ebselen (10mg/kg, oral gavage once daily) or vehicle (5% w/v CM cellulose in water) 1 h prior to the first CS exposure of the day. Upon sacrifice, bronchoalveolar lavage fluid (BALF) was collected to assess pulmonary inflammation and the thoracic aorta was excised to investigate vascular endothelial and smooth muscle dilator responses ex-vivo. Key Results: CS exposure caused a significant increase in lung inflammation which was reduced by ebselen. CS also caused significant endothelial dysfunction in the thoracic aorta which was attributed to a downregulation of eNOS expression and increased vascular oxidative stress. Ebselen abolished the aortic endothelial dysfunction seen in CS-exposed mice by reducing the oxidative burden and preserving eNOS expression. Conclusion and Implications: Targeting CS-induced oxidative stress with ebselen may provide a novel means for treating the life-threatening pulmonary and cardiovascular manifestations associated with cigarette smoking and COPD.
Background: Glucagon-like peptide-2 (GLP-2) is a 33 amino acid pro-glucagon-derived hormone produced in the intestinal enteroendocrine L-cells with trophic actions on both the gut and bones. GLP-2(1-33) is cleaved by the ubiquitous protease dipeptidyl peptidase-4 (DPP-4), resulting in GLP-2(3-33) with competitive antagonistic properties on the GLP-2 receptor (GLP-2R). Here we present two new hGLP-2 radioligands with different pharmacodynamic profiles. Experimental Approach: The methionine in position 10 of GLP-2(1-33) was substituted with tyrosine to enable oxidative iodination with incorporation of the iodine isotope [125I]. Similar substitution was done in GLP-2(3-33), thereby creating two new radioligands; an agonist -hGLP-2(1-33,M10Y) and an antagonist -hGLP-2(3-33,M10Y). Both were characterized regarding competition binding, binding kinetics and target tissue autoradiography. Key results: High and similar binding affinities for the human GLP-2R were observed for [125I]-hGLP-2(1-33,M10Y) and [125I]-hGLP-2(3-33,M10Y) with KD values of 59.3 nM and 40.6 nM, respectively. The M10Y substitution did not change the functional properties of GLP-2(1-33) or GLP-2(3-33). The antagonist [125I]-hGLP-2(3-33,M10Y) had higher Bmax and faster on-rate for the hGLP-2R compared to the agonist [125I]-hGLP-2(1-33,M10Y). Using autoradiography in mice strong labeling was observed in subepithelial myofibroblasts (SEMF) and pancreas islet cells. Both radioligands were selective for the GLP-2R, except for a low affinity binding to the GLP-1R (IC50 of 130 and 330 nM, respectively) Conclusion and implications: We successfully developed two new high affinity radioligands for GLP-2R studies and identified SEMF and pancreatic islets as target for GLP-2. It is uncertain whether binding in the pancreas islets results from GLP-2R or GLP-1R binding.
An increase in pulmonary artery pressure is a common observation in adult mammals exposed to alveolar hypoxia. It is considered a maladaptive response that places an increased workload on the right ventricle. The mechanisms initiating and maintaining the elevated pressure are of considerable interest to understanding pulmonary vascular homeostasis and developing new treatments for pulmonary hypertension. In particular, it would be helpful to discover the key molecules in the integrated vascular response to hypoxia to inform potential drug targets. One strategy is to take advantage of experiments of nature; specifically, to understand the molecular basis for the inter-individual variation in the pulmonary vascular response to acute and chronic hypoxia. This is the motivation for genetic studies in populations and animals adapted to life at high altitudes. To date, these studies highlight the importance of hypoxia-inducible factor 2α (HIF-2α), encoded by EPAS1, and prolyl hydroxylase domain-containing protein 2 (PHD), encoded by EGLN1, and support efforts to pharmacologically manipulate HIF-2 activity as a treatment for pulmonary hypertension.
Cancer cachexia is one of the most common causes of death among cancer patients, no effective anti-cachectic treatment is currently available. In experimental cachectic animal models, aberrant activation of STAT3 in skeletal muscle has been found to contribute to muscle wasting. However, its clinical association, the factors regulating STAT3 activation, and the molecular mechanisms remain incompletely understood. Here, we show that an enhanced interaction between activated STAT3 and HSP90, which were observed in the skeletal muscle of cancer cachexia patients, is a crucial event for the development of cachectic muscle wasting. Administration of HSP90 inhibitors 17DMAG and PU-H71 alleviated the muscle wasting in C26 tumor-bearing cachectic mice or the myotube atrophy of C2C12 cells induced by C26 conditional medium. A mechanistic study indicated that in cachectic skeletal muscle, prolonged STAT3 activation transactivated FOXO1 by binding directly to its promoter and triggered the muscle wasting in a FOXO1-dependent manner; Our results demonstrate that the HSP90/STAT3/FOXO1 axis plays a critical role in the cachectic muscle wasting, which might serve as potential therapeutic target for the treatment of cancer cachexia.
Background and Purpose Incubation of craving is associated with temporal changes in the activity of several structures involved in drug-seeking behavior. Hypodopaminergic activity, responsible for negative emotional states, has been reported in the ventral tegmental area (VTA) during cocaine abstinence. The neuroadaptations underlying the VTA hyperdopaminergic state after chronic cocaine is not well understood. In this work, we investigated the potential involvement of a VTA inhibiting circuit (amygdala-ventral pallidum (VP) pathway) in the hypodopaminergic state during abstinence from chronic cocaine. Experimental Approach In a model of cocaine self-administration, we performed in vivo electrophysiological recordings of DA VTA neurons and basolateral amygdala (BLA) neurons from anesthetized rats during early and protracted abstinence and evaluated the involvement of the BLA-VP pathway using a pharmacological approach. Key Results We found a significant decrease of VTA DA population activity and a significant increase of BLA activity after 30 days of abstinence from chronic cocaine but not one day. The decrease in VTA DA activity was restored by pharmacological inhibition of the activity of either the BLA or the VP. Conclusion and Implications Our study sheds new lights on neuroadaptations occurring during incubation of craving leading to relapse. In particular, we described the involvement of the BLA-VP pathway in cocaine-induced decreases of DA activity in the VTA. This study adds an important building block to the characterization of specific brain network dysfunctions underlying hypodopaminergic activity during abstinence.
Chronic liver diseases comprises a broad spectrum of burdensome diseases that still lack effective pharmacological therapies. Our research group focuses on Fibrosis which is a major precursor of liver cirrhosis. Fibrosis consists in a progressive disturbance of liver sinusoidal architecture characterised by connective tissue deposition as a reparative response to tissue injury. Multifactorial events and several types of cells, participate in fibrosis initiation and progression and the process still needs to be completely understood. The development of experimental models of liver fibrosis alongside the identification of critical factors progressing fibrosis to cirrhosis will facilitate the development of more effective therapeutic approaches for such condition. This review provides an overlook of the main process leading to hepatic fibrosis and therapeutic approaches that have emerged from a deep knowledge of the molecular regulation of fibrogenesis in the liver.
NK cells are an important arm of the innate immune system, and they constitutively express the NKp30 receptor. NKp30-mediated responses are triggered by the binding of specific ligands, such as tumour cell-derived B7-H6, and involve the secretion of cytotoxic mediators TNF-α, IFN-γ, perforins and granzymes. The latter two constitute a target cell-directed response that is critical in the process of immunosurveillance. The structure of NKp30 is presented, focusing on the ligand-binding site, on the ligand-induced structural changes, and on the experimental data available correlating structure and binding affinity. The translation of NKp30 structural changes to disease progression is also reviewed. NKp30 role in immunotherapy has been explored in chimeric antigen receptor T-cell (CAR-T) therapy. However, antibodies or small ligands targeting NKp30 have not yet been developed. The data reviewed unveils the key structural aspects that must be considered for drug design in order to develop novel immunotherapy approaches.
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that causes the progressive loss of motoneurons, and unfortunately, there is no effective treatment to stop the disease. Multiple pathological mechanisms are interconnected in the neuropathology of this disorder, including abnormal aggregation of proteins, neuroinflammation and dysregulation of the ubiquitin proteasome system. Such complex mechanisms, together with the lack of reliable animal models of the disease, have hampered drug discovery in the last decades. Protein kinases, key pharmacological targets in several diseases, have been linked to ALS, as they play a central role in numerous of these pathological mechanisms. Therefore, several inhibitors are currently in their way to achieve a clinical proof of concept in ALS patients. In this review we recapitulate the protein kinase inhibitors currently in development for this disease together with their molecular targets and their involvement in the pathobiology of ALS.
Oxidized low-density lipoproteins (oxLDL) and oxysterols play a key role in the endothelial dysfunction and atherosclerosis development. Loss of vascular endothelium integrity impacts vasomotion, cell growth, adhesiveness and barrier functions. While for some of these disturbances we can give a reasonable explanation from a mechanistic point of view, for many others the involved molecular players are unknown. Caveolae, specific plasma membrane domains, have recently emerged as targets and mediators of oxLDL-induced endothelial cell dysfunction. The current knowledge on oxLDL/caveolae interplay and the associated signal transduction pathways are here reviewed and discussed in light of the possible cross-talk between transducers (from receptors to membrane cholesterol) and/or effectors. A better understanding of how oxLDL interact with endothelial cells (EC) and, in turn, modulate metabolic/signaling pathways in EC is crucial to define their role in atherogenesis and find new targets of intervention.
Background and purpose: Alpha 7 nicotinic acetylcholine receptors (CHRNA7) suppress inflammation through diverse pathways in immune cells, so is potentially involved in a number of inflammatory diseases. However, the detailed mechanisms underlying CHRNA7’s anti-inflammatory effects remain elusive. Experimental approach: The anti-inflammatory effects of CHRNA7 agonists in both murine macrophages (RAW 264.7) and bone marrow-derived macrophages (BMDM) stimulated with LPS were examined. The role of adenylyl cyclase 6 (AC6) in Toll-like Receptor 4 (TLR4) degradation was explored via overexpression and knockdown. A mouse model of chronic obstructive pulmonary disease was used to confirm key findings. Key results: Anti-inflammatory effects of CHRNA7 were largely dependent on AC6 activation, as knockdown of AC6 considerably abnegated the effects of CHRNA7 agonists while AC6 overexpression promoted them. We found that CHRNA7 and AC6 are co-localized in lipid rafts of macrophages and directly interact. Activation of AC6 led to the promotion of TLR4 degradation. Administration of CHRNA7 agonist PNU282987 attenuated pathological and inflammatory end points in a mouse model of chronic obstructive pulmonary disease (COPD). Conclusion and implications: CHRNA7 inhibit inflammation through activating AC6 and promoting degradation of TLR4. The use of CHRNA7 agonists might represent a novel therapeutic approach for treating COPD and likely other inflammatory diseases.
Targeting cancer metabolism has emerged as an attractive approach to improve therapeutic regimens in acute myeloid leukemia (AML). Mitochondrial proteases are closely related to cancer metabolism, but their biological functions have not been well characterized in AML. According to different catogory, we comprehensively reviewed the role of mitochondrial proteases in AML. This review highlights some ‘powerful’ mitochondrial protease targets, including their biological function, chemical modulators, and applicative prospect in AML.