Human Precision-Cut Liver Slices: A Potential Platform to Study Alcohol-Related Liver Disease.

Alcohol-related liver disease (ALD) encompasses a range of pathological conditions that are complex to study at the clinical and preclinical levels. Despite the global burden of ALD, there is a lack of effective treatments, and mortality is high. One of the reasons for the unsuccessful development of novel therapies is that experimental studies are hindered by the challenge of recapitulating this multifactorial disorder in vitro, including the contributions of hepatotoxicity, impaired lipid metabolism, fibrosis and inflammatory cytokine storm, which are critical drivers in the pathogenesis of ALD in patients and primary targets for drug development. Here, we present the unique characteristics of the culture of human precision-cut liver slices (PCLS) to replicate key disease processes in ALD. PCLS were prepared from human liver specimens and treated with ethanol alone or in combination with fatty acids and lipopolysaccharide (FA + LPS) for up to 5 days to induce hepatotoxic, inflammatory and fibrotic events associated with ALD. Alcohol insult induced hepatocyte death which was more pronounced with the addition of FA + LPS. This mixture showed a significant increase in the cytokines conventionally associated with the prototypical inflammatory response observed in severe ALD, and interestingly, alcohol alone exhibited a different effect. Profibrogenic activation was also observed in the slices and investigated in the context of slice preparation. These results support the versatility of this organotypic model to study different pathways involved in alcohol-induced liver damage and ALD progression and highlight the applicability of the PCLS for drug discovery, confirming their relevance as a bridge between preclinical and clinical studies.

In vitro activity of N-acetylcysteine against Stenotrophomonas maltophilia and Burkholderia cepacia complex grown in planktonic phase and biofilm.

Stenotrophomonas maltophilia and Burkholderia cepacia complex (Bcc) have been increasingly recognized as relevant pathogens in hospitalized, immunocompromised and cystic fibrosis (CF) patients. As a result of complex mechanisms, including biofilm formation and multidrug resistance phenotype, S. maltophilia and Bcc respiratory infections are often refractory to therapy, and have been associated with a worse outcome in CF patients. Here we demonstrate for the first time that N-acetylcysteine (NAC), a mucolytic agent with antioxidant and anti-inflammatory properties, may exhibit antimicrobial and antibiofilm activity against these pathogens. The antimicrobial and antibiofilm activity of high NAC concentrations, potentially achievable by topical administration, was tested against a collection of S. maltophilia (n = 19) and Bcc (n = 19) strains, including strains from CF patients with acquired resistance traits. Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) ranged from 16 to 32 mg/ml and from 32 to >32 mg/ml, respectively. Sub-MIC concentrations (i.e., 0.25 × MIC) slowed down the growth kinetics of most strains. In time-kill assays, 2-day-old biofilms were more affected than planktonic cultures, suggesting a specific antibiofilm activity of NAC against these pathogens. Indeed, a dose- and time-dependent antibiofilm activity of NAC against most of the S. maltophilia and Bcc strains tested was observed, with a sizable antibiofilm activity observed also at 0.5 and 1 × MIC NAC concentrations. Furthermore, at those concentrations, NAC was also shown to significantly inhibit biofilm formation with the great majority of tested strains.

In vitro synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii grown in planktonic phase and in biofilms.

Objectives: To investigate the potential synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii strains grown in planktonic phase or as biofilms. Methods: Sixteen strains were investigated, including nine colistin-susceptible (MIC range 0.5-1 mg/L) and seven colistin-resistant (MIC range 16-256 mg/L) strains. Synergism of colistin in combination with N-acetylcysteine was investigated by chequerboard assays. The activity of colistin/N-acetylcysteine combinations was further evaluated by time-kill assays with planktonic cultures (three colistin-resistant strains and one colistin-susceptible strain) and by in vitro biofilm models (three colistin-resistant and three colistin-susceptible strains). Results: Chequerboard assays revealed a relevant synergism of colistin/N-acetylcysteine combinations with all colistin-resistant strains, whereas no synergism was observed with colistin-susceptible strains. Time-kill assays showed a concentration-dependent potentiation of colistin activity by N-acetylcysteine against colistin-resistant strains, with eradication of the culture by combinations of N-acetylcysteine at 8000 mg/L plus colistin at 2 or 8 mg/L. A static effect during the first 8 h of incubation was demonstrated with the colistin-susceptible strain exposed to 0.25 × MIC colistin plus 8000 mg/L N-acetylcysteine. A remarkable antibiofilm synergistic activity of 8 mg/L colistin plus 8000 mg/L N-acetylcysteine was demonstrated with all colistin-resistant and colistin-susceptible strains. The effects were greater with colistin-resistant strains (marked reduction of viable biofilm cells was observed at sub-MIC colistin concentrations). Conclusions: N-acetylcysteine, at concentrations achievable by topical administration, was shown to revert the colistin-resistant phenotype in A. baumannii, and to exert a relevant activity against biofilms of colistin-susceptible and colistin-resistant A. baumannii strains.

N-Acetylcysteine as an antioxidant and disulphide breaking agent: the reasons why.

The main molecular mechanisms explaining the well-established antioxidant and reducing activity of N-acetylcysteine (NAC), the N-acetyl derivative of the natural amino acid l-cysteine, are summarised and critically reviewed. The antioxidant effect is due to the ability of NAC to act as a reduced glutathione (GSH) precursor; GSH is a well-known direct antioxidant and a substrate of several antioxidant enzymes. Moreover, in some conditions where a significant depletion of endogenous Cys and GSH occurs, NAC can act as a direct antioxidant for some oxidant species such as NO2 and HOX. The antioxidant activity of NAC could also be due to its effect in breaking thiolated proteins, thus releasing free thiols as well as reduced proteins, which in some cases, such as for mercaptoalbumin, have important direct antioxidant activity. As well as being involved in the antioxidant mechanism, the disulphide breaking activity of NAC also explains its mucolytic activity which is due to its effect in reducing heavily cross-linked mucus glycoproteins. Chemical features explaining the efficient disulphide breaking activity of NAC are also explained.

Effect of High N-Acetylcysteine Concentrations on Antibiotic Activity against a Large Collection of Respiratory Pathogens.

The effect of high N-acetylcysteine (NAC) concentrations (10 and 50 mM) on antibiotic activity against 40 strains of respiratory pathogens was investigated. NAC compromised the activity of carbapenems (of mostly imipenem and, to lesser extents, meropenem and ertapenem) in a dose-dependent fashion. We demonstrated chemical instability of carbapenems in the presence of NAC. With other antibiotics, 10 mM NAC had no major effects, while 50 mM NAC sporadically decreased (ceftriaxone and aminoglycosides) or increased (penicillins) antibiotic activity.

Pharmacokinetic comparison of inhaled fixed combination vs. the free combination of beclomethasone and formoterol pMDIs in asthmatic children.

AIM: The fixed combination of beclomethasone (BDP) and formoterol pressurized metered dose inhaler (pMDI) (Foster®, Chiesi Farmaceutici) is being developed in the lower strength (BDP/formoterol: 50/6 µg) to provide an appropriate dosage for children with asthma. The aim of this work was to investigate the systemic bioavailability of beclomethasone-17-monoproprionate (B17MP, the active metabolite of BDP) and formoterol after single inhalation of Foster® pMDI 50/6 µg vs. the free combination of BDP and formoterol pMDIs in asthmatic children. METHODS: Children aged 5-11 years old inhaled BDP 200 µg and formoterol 24 µg as fixed vs. free combination in an open label, randomized, two way crossover single dose study. Blood was collected pre-dose up to 8 h post-dose for pharmacokinetic evaluation (AUC(0,t), AUC(0,∞), AUC(0,0.5 h, Cmax , tmax , t1/2 ). Pharmacodynamics included heart rate, plasma potassium, urinary glucose and cortisol excretion. Peak expiratory flow and adverse events were monitored. RESULTS: Twenty subjects were evaluable. The systemic exposure of B17MP and formoterol administered as fixed combination did not exceed the free combination: B17MP AUC(0,t) (pg ml(-1) h) ratio test : reference (90% CI), 0.81 (0.697, 0.948) and formoterol AUC(0,t) (pg ml(-1) h) ratio test : reference 0.97 (0.85, 1.10). All pharmacokinetic and pharmacodynamic end points showed non-superiority in favour of the test drug. One adverse event (vertigo) occurred but was not considered treatment-related. CONCLUSION: BDP and formoterol pharmacokinetic and pharmacodynamic effects are non-superior after administration of the two actives as fixed vs. the free combination in 5-11-year-old asthmatic children.

Systemic activity of inhaled beclomethasone dipropionate: a double-blind comparison of volume spacers.

BACKGROUND: To which extent volume spacers may influence systemic activity of inhaled beclomethasone dipropionate (BDP) has not been evaluated. AIM: To assess whether the AeroChamber Plus™ spacer is equivalent to the Volumatic™ spacer for administration of inhaled hydroflouroalkane 134a propelled BDP in terms of lower leg growth rate (LLGR). PATIENTS AND METHODS: Prepubertal children with mild asthma (n = 26, aged 6-14 years) were included in a 3-time periods of 2 weeks duration randomized double-blind cross-over study with a single-blind placebo run-in and two washout periods. LLGR was measured with the knemometer. Interventions were inhaled BDP hydroflouroalkane 134a pressurized metered dose inhaler 100 µg and 200 µg b.i.d. with the AeroChamber Plus and 200 µg b.i.d. with the Volumatic spacer. RESULTS: Beclomethasone dipropionate 200 µg b.i.d. from the AeroChamber Plus was non-inferior to BDP 200 b.i.d. from the Volumatic spacer as the lower margin of confidence interval of the difference between treatments (-0.18 to 0.13 mm/week) was greater than the prespecified lower limit for non-inferiority (-0.20 mm/week). UFC/creatinine data showed no statistically significant variations. CONCLUSION: The systemic activity of BDP, via the Volumatic™, and AeroChamber Plus™ spacers is similar. The AeroChamber Plus spacer may be used in children without risk of increasing systemic activity of BDP.

Walking capacity and fitness to fly in patients with chronic respiratory disease.

INTRODUCTION: In this study, we tested the hypothesis that walking capacity, assessed by the 6-min walk test (6MWT), could be related to the effect of flight simulation at sea level obtained by the hypoxia-altitude simulation test (HAST) in patients with chronic respiratory disease. METHODS: There were 15 patients with interstitial lung disease and 15 patients with chronic obstructive pulmonary disease who were recruited. Their baseline SpO2 values ranged from 88 to 98%. All patients performed the 6MWT and HAST according to standardized methods. RESULTS: Patients covered a walking distance ranging from 185 to 592 m without stopping while experiencing no to severe dyspnea. No correlation was found between dyspnea perception during walking, walking distance, and oxygen desaturation during HAST. The oxygen desaturation induced by the 6MWT was related to that after HAST (r = 0.52, p < 0.01). The bias and limits of agreement between the oxygen desaturation after the 6MWT and after the HAST were 0.8 and -6.6 to 8.2%, respectively. The baseline SpO2 could reliably predict the oxygen desaturation during HAST (r2 = 0.51). CONCLUSIONS: Our results showed that measurement of SpO2 during 6MWT can provide useful information for the preflight assessment and the in-flight oxygen prescription of patients with chronic respiratory disease.