Role of m2 muscarinic receptor in the airway response to methacholine of mice selected for minimal or maximal acute inflammatory response

Cytotoxic Activity and Lymphocyte Subtypes in Mice Selected for Maximal and Minimal Inflammatory Response after Transplantation of B16F10 and S91 Melanoma Cells

AIRmax and AIRmin mice strains were selected according to the intensity of their acute inflammatory responsiveness. Previous studies have shown that AIR mice differ in their resistance to chemically induced skin tumors and in the development of melanoma metastases, in addition to differences in neutrophil and NK cells activity. In the present work, we aimed to evaluate whether the difference of susceptibility to murine melanoma is associated with NK cytotoxic activity against Yac.1 cells and lymphocyte subsets. Mice were subcutaneously inoculated with B16F10 or S91 melanoma cells. After 7, 14, or 30 days, the animals were euthanized to analyze the number of lymphocyte subsets, cytotoxic activity, and number of cytokine-producing spleen cells. AIRmax mice presented a higher number of CD4⁺/CD25⁺ cells than that of AIRmin mice following inoculation of B16F10 cells, whereas inoculation of S91 cells reduced CD4⁺/CD25⁺ and increased TCD8⁺ cell subsets in the AIRmax mice. AIRmax mice had a higher number of interleukin (IL)-10- and IL-12-producing cells and a lower number of interferon-γ–producing cells than those of AIRmin mice at 30 days. The cytotoxic activity of nonadherent spleen cells was similar in both the AIR strains. These results suggest that melanoma cells can induce different responses in AIR mice, possibly owing to alterations in regulatory mechanisms, such as the action of CD4⁺/CD25⁺ regulatory T cells and IL-10, in AIRmax mice.

Differential Actions of Muscarinic Receptor Subtypes in Gastric, Pancreatic, and Colon Cancer

Cancers arising from gastrointestinal epithelial cells are common, aggressive, and difficult to treat. Progress in this area resulted from recognizing that the biological behavior of these cancers is highly dependent on bioactive molecules released by neurocrine, paracrine, and autocrine mechanisms within the tumor microenvironment. For many decades after its discovery as a neurotransmitter, acetylcholine was thought to be synthesized and released uniquely from neurons and considered the sole physiological ligand for muscarinic receptor subtypes, which were believed to have similar or redundant actions. In the intervening years, we learned this former dogma is not tenable. (1) Acetylcholine is not produced and released only by neurons. The cellular machinery required to synthesize and release acetylcholine is present in immune, cancer, and other cells, as well as in lower organisms (e.g., bacteria) that inhabit the gut. (2) Acetylcholine is not the sole physiological activator of muscarinic receptors. For example, selected bile acids can modulate muscarinic receptor function. (3) Muscarinic receptor subtypes anticipated to have overlapping functions based on similar G protein coupling and downstream signaling may have unexpectedly diverse actions. Here, we review the relevant research findings supporting these conclusions and discuss how the complexity of muscarinic receptor biology impacts health and disease, focusing on their role in the initiation and progression of gastric, pancreatic, and colon cancers.

Safety and Pharmacokinetics of HTL0018318, a Novel M1 Receptor Agonist, Given in Combination with Donepezil at Steady State: A Randomized Trial in Healthy Elderly Subjects

INTRODUCTION

HTL0018318 is a selective muscarinic M1 receptor partial agonist under development for the symptomatic treatment of dementias, including Alzheimer's disease. Clinically, HTL0018318 would likely be used alone or in conjunction with cholinesterase inhibitors (e.g. donepezil).

OBJECTIVE

We investigated the safety, tolerability, and pharmacokinetics of HTL0018318 given alone and in combination with donepezil.

METHODS

This was a randomized, double-blind, placebo-controlled trial in 42 (to deliver 36 with combination treatment) healthy elderly subjects investigating the effects of oral HTL0018318 15 and 25 mg given alone and combined with donepezil 10 mg at steady state on adverse events (AEs), vital signs, saliva production, sleep quality, pulmonary function, subjective feelings, and pharmacokinetics.

RESULTS

AEs were reported by lower percentages of subjects after HTL0018318 alone than after donepezil alone. There was no increase in the percentage of subjects reporting AEs after co-administration than after donepezil alone. Supine systolic blood pressure was 1.6 mmHg (95% confidence interval [CI] -3.1 to -0.1) lower after HTL0018318 alone than after combination treatment. This was comparable with results from placebo alone: 1.7 mmHg (95% CI -3.2 to 0.2) lower than with combination treatment. Supine pulse rate was 3.3 bpm (95% CI 1.5-5.1) higher after HTL0018318 alone than with co-administration. HTL0018318 and donepezil did not meaningfully affect each other's pharmacokinetics.

CONCLUSION

HTL0018318 was well tolerated when given alone and in combination with donepezil. HTL0018318 and donepezil do not demonstrate pharmacokinetic or pharmacodynamic interactions, indicating that HTL0018318 can be safely administered in combination with donepezil.

CLINICAL TRIAL REGISTRATION

Netherlands Trial register identifier NL5915, registered on 28 October 2016.

Na+/H+ Exchanger Regulatory Factor 1 Mediates the Pathogenesis of Airway Inflammation in a Murine Model of House Dust Mite-Induced Asthma

Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1), a class I PDZ-binding protein, regulates G protein-coupled receptor signaling in some cell types. NHERF1 also functions as a scaffolding protein and activates non-G protein-coupled receptor signaling pathways, thereby contributing to the pathogenesis of various diseases. Although we have previously shown that NHERF1 regulates mast cell functions, there is little information regarding the role of NHERF1 in other immune cells. How NHERF1 regulates the pathogenesis of allergic disease such as asthma also remains unknown. In the current study, we show that NHERF1 promotes allergic airway inflammation in a house dust mite extract (HDME)-induced mouse model of asthma. Specifically, HDME-specific serum IgE levels, airway leukocyte numbers, and goblet cell hyperplasia were reduced in NHERF1^+/- mice as compared with NHERF1^+/+ mice. Interestingly, the gene expression of inflammatory (IL-17a, IL-25, and IL-33) as well as T helper 2 (Th2) cytokines (IL-4, IL-5, and IL-13) and several chemokines that recruit eosinophils, neutrophils, and lymphocytes were also decreased in the lungs of NHERF1^+/- mice exposed to HDME. Consistent with these observations, microRNAs regulating mucus production, inflammation, Th2 effector functions, and IL-13 expression were increased in the lungs of HDME-treated NHERF1^+/- mice. Overall, our studies reveal a unique role for NHERF1 in regulating asthma pathogenesis, and further elucidation of the mechanisms through which NHERF1 modulates allergic inflammation will lead to the development of new therapeutic strategies for asthma.

Mesenchymal Stem Cells Induce Suppressive Macrophages Through Phagocytosis in a Mouse Model of Asthma

Mesenchymal stem cell (MSC) immunosuppressive functions make them attractive candidates for anti-inflammatory therapy in allergic asthma. However, the mechanisms by which they ensure therapeutic effects remain to be elucidated. In an acute mouse model of house dust mite (Der f)-induced asthma, one i.v. MSC injection was sufficient to normalize and stabilize lung function in Der f-sensitized mice as compared to control mice. MSC injection decreased in vivo airway responsiveness and decreased ex vivo carbachol-induced bronchial contraction, maintaining bronchial expression of the inhibitory type 2 muscarinic receptor. To evaluate in vivo MSC survival, MSCs were labeled with PKH26 fluorescent marker prior to i.v. injection, and 1 to 10 days later total lungs were digested to obtain single-cell suspensions. 91.5 ± 2.3% and 86.6 ± 6.3% of the recovered PKH26(+) lung cells expressed specific macrophage markers in control and Der f mice, respectively, suggesting that macrophages had phagocyted in vivo the injected MSCs. Interestingly, only PKH26(+) macrophages expressed M2 phenotype, while the innate PKH26(-) macrophages expressed M1 phenotype. Finally, the remaining 0.5% PKH26(+) MSCs expressed 10- to 100-fold more COX-2 than before injection, suggesting in vivo MSC phenotype modification. Together, the results of this study indicate that MSCs attenuate asthma by being phagocyted by lung macrophages, which in turn acquire a M2 suppressive phenotype. Stem Cells 2016;34:1836-1845.

Airway and lung remodelling in chronic pulmonary obstructive disease: a role for muscarinic receptor antagonists?

Lung tissue remodelling in chronic inflammatory lung diseases has long been regarded as a follow-up event to inflammation. Recent studies have indicated that, although airway and lung tissue remodelling is often independent of inflammation, it precedes or causes inflammation. None of the available therapies has a significant effect on airway and lung tissue remodelling in asthma, bronchiectasis, fibrosis and chronic obstructive pulmonary disease (COPD). The goal of stopping or reversing lung tissue remodelling is difficult, as the term summarizes the net effect of independent events, including (1) cell proliferation, (2) cell volume increase, (3) cell migration, (4) modified deposition and metabolism of specific extracellular matrix components, and (5) local action of infiltrated inflammatory cells. The extracellular matrix of the lung has a very high turnover, and thus small changes may accumulate to significant structural pathologies, which seem to be irreversible. The most important question is 'why are pathological changes of the lung structure irreversible and resistant to drugs?' Many drugs have the potential to reduce remodelling mechanisms in vitro but fail in clinical trials. New evidence suggests that muscarinic receptor inhibitors have the potential to improve lung function through modifying tissue remodelling. However, the role of muscarinic receptors in lung remodelling, especially their supportive role for other remodelling driving factors, needs to be further investigated. The focus of this review is the role of muscarinic receptors in lung tissue remodelling as it has been reported in the human lung.