Tiotropium increases cytosolic muscarinic M3 receptors and acetylated H3 histone proteins in induced sputum cells of COPD patients

Tiotropium Bromide Improves Neutrophilic Asthma by Recovering Histone Deacetylase 2 Activity

BACKGROUND

The value of tiotropium bromide (TIO) in neutrophilic asthma was meaningful in previous study. We hypothesized that TIO's mechanism of action is associated with histone deacetylase 2 (HDAC2) activity, which is key for controlling the transcription of inflammatory cytokines and usually downregulated in neutrophilic asthma.

METHODS

The effects of TIO and dexamethasone (DEX) on HDAC2 activity, nuclear factor kappa B (NF-κB), and C-X-C motif chemokine ligand 1 (CXCL1) were evaluated in neutrophilic asthma mouse model (C57BL, 6-week-old). An in-vitro study was conducted using primary human bronchial/tracheal epithelial (HBE) cells from asthma patients. Western blot analyses were performed for phospho-phospholipase Cγ-1 (PLCγ-1) and inositol trisphosphate (IP₃) receptors (IP₃R) with treating lipopolysaccharide (LPS) and TIO.

RESULTS

Ovalbumin was used to induce eosinophilic inflammation in this study. After neutrophilic asthma was induced by LPS (O+L group), HDAC2 activity was diminished with increased NF-κB activity and CXCL1 compared to the control group. TIO significantly improved NF-κB activity, CXCL1, and HDAC2 activity compared with the O+L group in in-vivo study (P < 0.05, each). Western blot analyses showed that LPS treated HBE cells from asthma patients increased PLCγ-1 and diminished IP₃ receptor levels. After TIO treatment, recovery of IP₃R and improved PLCγ-1 levels were observed.

CONCLUSION

These results support the hypothesis that TIO modulates inflammation by recovering HDAC2 activity from the acetylcholine-stimulated inflammation cascade in neutrophilic asthma. The detailed inflammation cascade of recovering HDAC2 activity by TIO might be associated with PLCγ-1-IP₃-IP₃R mediated intracellular calcium ion pathway.

The Impact of Muscarinic Receptor Antagonists on Airway Inflammation: A Systematic Review

Long-acting muscarinic receptor antagonists (LAMAs) are the cornerstone for the treatment of chronic obstructive pulmonary disease (COPD); furthermore, tiotropium is approved as add-on therapy in severe asthmatic patients. Accumulating evidence suggests that LAMAs may modulate airway contractility and airway hyperresponsiveness not only by blocking muscarinic acetylcholine receptors (mAchRs) expressed on airway smooth muscle but also via anti-inflammatory mechanisms by blocking mAchRs expressed on inflammatory cells, submucosal glands, and epithelial cells. The aim of this systematic review, performed according to the PRISMA-P guidelines, was to provide a synthesis of the literature on the anti-inflammatory impact of muscarinic receptor antagonists in the airways. Most of the current evidence originates from studies on tiotropium, that demonstrated a reduction in synthesis and release of cytokines and chemokines, as well as the number of total and differential inflammatory cells, induced by different pro-inflammatory stimuli. Conversely, few data are currently available for aclidinium and glycopyrronium, whereas no studies on the potential anti-inflammatory effect of umeclidinium have been reported. Overall, a large body of evidence supports the beneficial impact of tiotropium against airway inflammation. Further well-designed randomized controlled trials are needed to better elucidate the anti-inflammatory mechanisms leading to the protective effect of LAMAs against exacerbations via identifying suitable biomarkers.

Effect of Tiotropium Bromide on Airway Inflammation and Programmed Cell Death 5 in a Mouse Model of Ovalbumin-Induced Allergic Asthma

Rationale

We previously demonstrated increased expression of programmed cell death 5 (PDCD5) in asthmatic patients and ovalbumin-induced allergic asthma. International guidelines (GINA 2019) have included the use of tiotropium bromide for chronic treatment of the most severe and frequently exacerbated asthma in patients ≥6 years old, who do not have good response to inhaled corticosteroids.

Objective

To explore the role of tiotropium and its effect on PDCD5 level in a mouse model of chronic asthma.

Methods

We divided 12 female mice into 2 groups: untreated asthma (n = 6) and tiotropium-treated asthma (n = 6). The impact of tiotropium was assessed by histology of lung tissue and morphometry. Pulmonary function was tested by using pressure sensors. The number of cells in bronchoalveolar lavage fluid (BALF) was detected. Levels of PDCD5, active caspase-3, and muscarinic acetylcholine receptors M2 (ChRM2) and M3 (ChRM3) were examined.

Results

Tiotropium treatment significantly reduced airway inflammation and remodeling in asthmatic mice and intensified the lung function. PDCD5 level was reduced with tiotropium (p < 0.05). Moreover, active caspase-3 level was decreased with tiotropium (p < 0.001), and ChRM3 level was increased.

Conclusions

Tiotropium treatment may alleviate the pathological changes with asthma by regulating apoptosis.

Siglec-8 in induced sputum of COPD patients

Chronic obstructive pulmonary disease (COPD) is related to infiltration and activation of inflammatory cells in airways and pulmonary tissue. In COPD, neutrophils are prominent, while eosinophilic influx is typical to asthma. Inflammatory cells express sialic acid-binding immunoglobulin like lectins called Siglecs, a family of innate immune receptors that are transmembrane I-type lectins binding sialic acid. One member of the Siglec family, Siglec-8, is expressed mostly in eosinophils and may be an important therapeutic target in asthma or COPD. The aim of our project was to quantify Siglec-8 expression in induced sputum cells of COPD patients treated with long-acting beta2-agonists (LABA) or combined with long-acting antimuscarinic agents (LAMA) - tiotropium bromide. Thirty stable COPD patients (21 males and 9 females, mean age 67 years) receiving 12 μg BID formoterol therapy were assessed before and after 3 months' add-on therapy consisting of 18 μg QID tiotropium. In all patients, spirometry, lung volumes, and DLCO were performed before and after therapy. The patients were subjected to sputum induction before and after therapy. Sputum cells were isolated and processed to obtain cell membranes. Siglec-8 protein expression was assessed using Western blot. In patients receiving tiotropium and formoterol, improved FEV1 and lung volumes were observed compared with formoterol-only treated patients. The mean Siglec-8 level was significantly higher in eosinophilic subgroup of COPD patients compared with non-eosinophilic patients before therapy 40,000 vs. 15,000 Adj. Vol. INT/mm(2). Our data show that Siglec-8 may be involved in COPD pathogenesis and may influence COPD phenotyping.

Tregs and HLA-DR expression in sputum cells of COPD patients treated with tiotropium and formoterol

Immune cells expressing the activation markers HLA-DR and regulatory T cells (Tregs) may be involved in the regulation of chronic inflammation in chronic obstructive pulmonary disease (COPD). In this study we analyzed native and activated cell profiles in sputum of 22 stable COPD patients receiving formoterol (F) or formoterol + tiotropium (F + T) for 3 months. Cells were isolated from induced sputum and were examined on Coulter flow cytometer using fluorescent antibodies specific for CD3, CD4, CD8, CD14, CD19, CD25, CD127, and HLA-DR antigens. Cell profiles and cell activation were assessed by analysis of HLA-DR, CD25, and CD127 co-expression in double-stained samples. Tregs were defined as CD4⁺CD25(high) CD127(low) cells. We found that the combined therapy significantly decreased the CD8⁺ cell number (p < 0.01). At baseline, HLA-DR was expressed in about 10 % of sputum T or B cells and a higher expression was found on monocytes. The HLA-DR expression on lymphocytes, but not monocytes, was significantly lower (p < 0.01) in patients treated with F + T. Fractions of activated [CD4⁺ CD25⁺] cells were also significantly lower in the combined therapy group, except for the subpopulation of CD4⁺CD25(high) CD127(low) cells which was not altered. We conclude that tiotropium in add-on therapy to formoterol affects Treg cell profiles and decreases HLA-DR expression in airway lymphocytes.

Role of parasympathetic nerves and muscarinic receptors in allergy and asthma

Parasympathetic nerves control the symptoms and inflammation of allergic diseases primarily by signaling through peripheral muscarinic receptors. Parasympathetic signaling targets classic effector tissues such as airway smooth muscle and secretory glands and mediates acute symptoms of allergic disease such as airway narrowing and increased mucus secretion. In addition, parasympathetic signaling modulates inflammatory cells and non-neuronal resident cell types such as fibroblasts and smooth muscle contributing to chronic allergic inflammation and tissue remodeling. Importantly, muscarinic antagonists are experiencing a rebirth for the treatment of asthma and may be useful for treating other allergic diseases.