The protective effects of Ambroxol in Pseudomonas aeruginosa-induced pneumonia in rats

Discovery of novel inhibitors for Pseudomonas aeruginosa lipase enzyme from in silico and in vitro studies

Pseudomonas aeruginosa is an opportunistic pathogen prone to developing drug-resistance and is a major cause of infection for burn patients and patients suffering from cystic fibrosis or are hospitalized in intensive care units. One of the virulence factors of this bacterium is the lipase enzyme that degrades the extracellular matrix of the host tissue and promotes invasion. Bromhexine is a mucolytic drug and has recently been reported to function as a competitive inhibitor of lipase with an IC50 value of 49 µM. In the present study, an attempt was made to identify stronger inhibitors from the ChEMBL database of bioactive compounds, as compared to the reference compound Bromhexine. Following docking and MD simulations, four hit compounds (N1-N4) were selected that showed promising binding modes and low RMSD values indicative of stable protein-ligand complexes. From subsequent binding pose metadynamics (BPMD) simulations, two of these (N2 and N4) stood out as more potent than Bromhexine, displaying stable interactions with residues in the catalytic site of the enzyme. Biological investigations were performed for all four compounds. Among them, the same two hit compounds were found to be the most effective binders with IC50 values of 22.1 and 27.5 µM, respectively; i.e. roughly twice as efficient as the reference Bromhexine. Taken together, our results show that these hits can be promising new candidates to use as leads for the development of drugs targeting the P. aeruginosa lipase enzyme.Communicated by Ramaswamy H. Sarma.

Sodium houttuyfonate effectively treats acute pulmonary infection of Pseudomonas aeruginosa by affecting immunity and intestinal flora in mice

Introduction

Pseudomonas aeruginosa is a major nosocomial pathogen that frequently causes ventilator-associated pneumonia in specific populations. Sodium houttuyfonate (SH) has shown mild antibacterial activity against P. aeruginosa in vitro, but the mechanism of potent antimicrobial activity of SH against P. aeruginosa infection in vivo remains unclear.

Methods

Here, using the mouse pneumonia model induced by P. aeruginosa nasal drip to explore the therapeutic effects of SH.

Results

We found that SH exhibits dose-dependent therapeutic effects of reducing P. aeruginosa burden and systemic inflammation in pneumonia mice. SH ameliorates inflammatory gene expression and production of inflammatory proteins, such as interleukin-6 (IL-6), nuclear factor kappa-B (NF-κB) and toll-like receptor 4 (TLR4), associated with the TLR4/NF-κB pathway in mice with P. aeruginosa pneumonia. Furthermore, we analyzed the intestinal flora of mice and found that compared with the model group, the abundance and diversity of beneficial bacterial flora of SH treatment groups increased significantly, suggesting that SH can improve the intestinal flora disorder caused by inflammation. In addition, SH improves alpha and beta diversity index and reduces species abundance differences of intestinal flora in pneumonia mice.

Discussion

Taken together, our presented results indicate that SH may effectively alleviate the acute pulmonary infection induced by P. aeruginosa by reducing the disturbance of regulating immunity and intestinal flora in mice.

Potential new treatment strategies for COVID-19: is there a role for bromhexine as add-on therapy?

Of huge importance now is to provide a fast, cost-effective, safe, and immediately available pharmaceutical solution to curb the rapid global spread of SARS-CoV-2. Recent publications on SARS-CoV-2 have brought attention to the possible benefit of chloroquine in the treatment of patients infected by SARS-CoV-2. Whether chloroquine can treat SARS-CoV-2 alone and also work as a prophylactic is doubtful. An effective prophylactic medication to prevent viral entry has to contain, at least, either a protease inhibitor or a competitive virus ACE2-binding inhibitor. Using bromhexine at a dosage that selectively inhibits TMPRSS2 and, in so doing, inhibits TMPRSS2-specific viral entry is likely to be effective against SARS-CoV-2. We propose the use of bromhexine as a prophylactic and treatment. We encourage the scientific community to assess bromhexine clinically as a prophylactic and curative treatment. If proven to be effective, this would allow a rapid, accessible, and cost-effective application worldwide.

Effects of the expectorant drug ambroxol hydrochloride on chemically induced lung inflammatory and neoplastic lesions in rodents

Ambroxol hydrochloride (AH) is an expectorant drug used to stimulate pulmonary surfactant and serous airway secretion. Surfactant proteins (SPs) are essential for maintaining respiratory structure and function, although SP expression has also been reported in lung inflammatory and proliferative lesions. To determine whether AH exerts modulatory effects on these lung lesions, we examined its effects on pleural thickening induced by intrathoracic administration of dipotassium titanate (TISMO) in A/JJmsSlc (A/J) mice. We also analyzed the modulatory effects of AH on neoplastic lung lesions induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice and by N-nitrosobis (2-hydroxypropyl) amine (DHPN) in F344/DuCrlCrj (F344) rats. A/J mice treated with TISMO showed decreased body weight, increased white blood cell (WBC) counts, and pleural thickening caused by pleuritis and poor general condition. However, A/J mice treated with TISMO + 120 ppm showed significant recovery of body weight and WBC counts to the same levels as those of A/J mice not treated with TISMO, although no significant differences were observed in histopathological changes including the immunohistopathological expression of IL-1β in the lung and maximum pleural thickness regardless of AH treatment. In the NNK and DHPN experiments, no significant differences in body weight, hematology, plasma biochemistry, and histopathological changes were associated with AH concentration. These results suggest that AH potentially exerts anti-inflammatory effects but does not have a direct suppressive effect on lung tumorigenesis in rodents.

Characteristics of surfactant proteins in tumorigenic and inflammatory lung lesions in rodents

Surfactant proteins (SPs) are essential for the proper structure and respiratory function of the lungs. There are four subtypes of SPs: SP-A, SP-B, SP-C, and SP-D. The expectorant drug ambroxol hydrochloride is clinically used to stimulate pulmonary surfactant and airway serous secretion. In addition, previous studies showed that ambroxol regulated SP production and attenuated pulmonary inflammation, with ambroxol hydrochloride being found to suppress quartz-induced lung inflammation via stimulation of pulmonary surfactant and airway serous secretion. In this study, we investigated the expression of SP-A, SP-B, SP-C, and SP-D in neoplastic and inflammatory lung lesions in rodents, as well as their possible application as potential markers for diagnostic purposes. SP-B and SP-C showed strong expression in lung hyperplasia and adenoma, whereas SP-A and SP-D were expressed in the mucus or exudates of inflammatory alveoli. Rodent tumorigenic hyperplasic tissues induced by various carcinogens were positive for napsin A, an aspartic proteinase involved in the maturation of SP-B; this indicated a focal increase in type II pneumocytes in the lungs. Therefore, high expression of napsin A in the alveolar walls may serve as a useful marker for prediction of the tumorigenic potential of lung hyperplasia in rodents.

[More than expectorant: new scientific data on ambroxol in the context of the treatment of bronchopulmonary diseases]

BACKGROUND

Ambroxol has been established for decades in the treatment of acute and chronic respiratory diseases. In 2015, the European Medicines Agency reassessed the clinical benefit-risk ratio of the drug.

OBJECTIVE

What new scientific data on ambroxol, which are relevant to the treatment of bronchopulmonary diseases, are available?

METHOD

The review is based on a systematic literature research in medline with the search term "ambroxol" during the publication period 2006-2015. Non-relevant publications were excluded manually.

RESULTS AND CONCLUSIONS

Ambroxol is still intensively researched. The traditional indication as an expectorant is confirmed. But there is also an ever better understanding of the various mechanisms of action as well as the ever more exact modeling of the structures under investigation. New fields of application are conceivable, e. g. in patients with severe pulmonary disease who undergo surgery or who are in intensive care, as an adjuvant in anti-infective therapies, especially in infections with biofilm-producing pathogens, or in rare diseases such as lysosomal storage diseases. However, final evidence of the clinical relevance in these fields of application is still missing.

Suppressive effects of the expectorant drug ambroxol hydrochloride on quartz-induced lung inflammation in F344 rats

Surfactant proteins (SPs) are essential to respiratory structure and function. The expectorant drug ambroxol hydrochloride is clinically prescribed to stimulate pulmonary surfactant and airway serous secretion. Therefore, ambroxol hydrochloride may affect SP production and pulmonary inflammation. Lung toxicity of fine particles of various materials has been examined previously in our in vivo bioassay using the intratracheal (i.t.) instillation approach. In the present study, we evaluated modulatory effects of ambroxol hydrochloride on quartz-induced lung inflammation in F344 rats. Male 6-week-old F344 rats were exposed by i.t. instillation to 2 mg of quartz particles suspended in 0.2 mL of saline. Ambroxol hydrochloride was administered at 0, 12, and 120 ppm in rat basal diet for 28 days, and then formalin-fixed paraffin-embedded lung, liver, and kidney samples were prepared. No changes in general condition, body and organ weights, or food consumption upon exposure to quartz were noted. The mean ambroxol intake in rats of the 12 ppm group was comparable to the human conventional dose. Histopathology of lung lesions was evaluated, and the degree of inflammation was scored. At 120 ppm, ambroxol hydrochloride significantly decreased individual lung inflammation scores for pulmonary edema and lymph follicle proliferation around the bronchiole, as well as the total inflammation score, in quartz-treated rats. Expression of SP-C in the type II alveolar cells and macrophages was greater in inflammatory lesions than in non-inflamed areas. Ambroxol treatment did not affect expression of SP-B and SP-C. In conclusion, we demonstrated that ambroxol hydrochloride relieves quartz-induced lung inflammation.

Ciprofloxacin plus erythromycin or ambroxol ameliorates endotracheal tube-associated Pseudomonas aeruginosa biofilms in a rat model

BACKGROUND AND OBJECTIVE

Pseudomonas aeruginosa is a multi-drug resistant bacterium, with its biofilm-growing mucoid (alginate-producing) strains being particularly resistant. As atomized drug administration is a common practice in pediatric patients, we compared the effect of inhalational therapy with erythromycin plus ciprofloxacin, with that of ambroxol plus ciprofloxacin, against biofilm producing strains of P. aeruginosa.

RESULTS

Both combined treatment regimens were associated with a significant reduction in bacterial counts in endotracheal (ET) tubes and lungs, as compared to that observed with ambroxol and erythromycin monotherapies (P<0.05). Ciprofloxacin plus ambroxol appeared to have a higher efficacy than ciprofloxacin plus erythromycin, both in lowering bacterial counts (P<0.05) and in disrupting the structural integrity of biofilm. Histopathological changes in the lungs were milder in the two combined treatment groups, as compared to that in groups treated with single drugs.

CONCLUSION

Erythromycin or ambroxol in combination with ciprofloxacin could eliminate P. aeruginosa biofilms. When combined with ciprofloxacin, ambroxol outperformed erythromycin in eradicating P. aeruginosa biofilm.

Biofilm-dependent airway infections: a role for ambroxol?

Biofilms are a key factor in the development of both acute and chronic airway infections. Their relevance is well established in ventilator associated pneumonia, one of the most severe complications in critically ill patients, and in cystic fibrosis, the most common lethal genetic disease in Caucasians. Accumulating evidence suggests that biofilms could have also a role in chronic obstructive pulmonary disease and their involvement in bronchiectasis has been proposed as well. When they grow in biofilms, microorganisms become multidrug-resistant. Therefore the treatment of biofilm-dependent airway infections is problematic. Indeed, it still largely based on measures aiming to prevent the formation of biofilms or remove them once that they are formed. Here we review recent evidence suggesting that the mucokinetic drug ambroxol has specific anti-biofilm properties. We also discuss how additional pharmacological properties of this drug could be beneficial in biofilm-dependent airway infections. Specifically, we review the evidence showing that: 1-ambroxol exerts anti-inflammatory effects by inhibiting at multiple levels the activity of neutrophils, and 2-it improves mucociliary clearance by interfering with the activity of airway epithelium ion channels and transporters including sodium/bicarbonate and sodium/potassium/chloride cotransporters, cystic fibrosis transmembrane conductance regulator and aquaporins. As a whole, the data that we review here suggest that ambroxol could be helpful in biofilm-dependent airway infections. However, considering the limited clinical evidence available up to date, further clinical studies are required to support the use of ambroxol in these diseases.