Oral cysteamine as an adjunct treatment in cystic fibrosis pulmonary exacerbations: An exploratory randomized clinical trial

Cysteamine-mediated blockade of the glycine cleavage system modulates epithelial cell inflammatory and innate immune responses to viral infection

Transient blockade of glycine decarboxylase (GLDC) can restrict de novo pyrimidine synthesis, which is a well-described strategy for enhancing the host interferon response to viral infection and a target pathway for some licenced anti-inflammatory therapies. The aminothiol, cysteamine, is produced endogenously during the metabolism of coenzyme A, and is currently being investigated in a clinical trial as an intervention in community acquired pneumonia resulting from viral (influenza and SARS-CoV-2) and bacterial respiratory infection. Cysteamine is known to inhibit both bacterial and the eukaryotic host glycine cleavage systems via competitive inhibition of GLDC at concentrations, lower than those required for direct antimicrobial or antiviral activity. Here, we demonstrate for the first time that therapeutically achievable concentrations of cysteamine can inhibit glycine utilisation by epithelial cells and improve cell-mediated responses to infection with respiratory viruses, including human coronavirus 229E and Influenza A. Cysteamine reduces interleukin-6 (IL-6) and increases the interferon-λ (IFN-λ) response to viral challenge and in response to liposomal polyinosinic:polycytidylic acid (poly I:C) simulant of RNA viral infection.

A contact-polymerizable hemostatic powder for rapid hemostasis

The immediate control of a hemorrhage is crucial for reducing fatalities in critical situations such as battlefields, traffic accidents, natural disasters, etc. Most existing commercial hemostatic powders have weak adhesion capability and poor biodegradability, restricting their clinical use. In this paper, a new poly(ethylene glycol)-di(cyanoacrylate) (CA-PEG-CA)-based hemostatic powder with tissue-contact-triggered strong adhesion and controlled fast degradation is proposed. The monomers quickly underwent crosslinking polymerization while in contact with tissue or blood, forming an in situ gel on the wound. The hemostatic mechanism was demonstrated to depend on both adhesive-based sealing and the aggregation of platelets and erythrocytes. The powder showed excellent hemostatic effects both in vitro and in vivo, even in a rat model with a weakened native hemostatic capacity. In addition, the poly-CA-PEG-CA gel could be rapidly biodegraded by ester bond hydrolysis. Notably, a cysteamine (CS)-containing solution could accelerate the degradation rate, endowing the gel with an on-demand removal property. This hemostatic powder not only can be used to efficiently control bleeding in emergency scenarios, but it can also allow nontraumatic re-exposure of wounds during subsequent surgical care. These properties make the CA-PEG-CA powder a promising candidate to act as a multifunctional wound care agent for first aid.

Cysteamine/Cystamine Exert Anti-Mycobacterium abscessus Activity Alone or in Combination with Amikacin

Host-directed therapies are emerging as a promising tool in the curing of difficult-to-treat infections, such as those caused by drug-resistant bacteria. In this study, we aim to test the potential activity of the FDA- and EMA-approved drugs cysteamine and cystamine against Mycobacterium abscessus. In human macrophages (differentiated THP-1 cells), these drugs restricted M. abscessus growth similar to that achieved by amikacin. Here, we use the human ex vivo granuloma-like structures (GLS) model of infection with the M. abscessus rough (MAB-R) and smooth (MAB-S) variants to study the activity of new therapies against M. abscessus. We demonstrate that cysteamine and cystamine show a decrease in the number of total GLSs per well in the MAB-S and MAB-R infected human peripheral blood mononuclear cells (PBMCs). Furthermore, combined administration of cysteamine or cystamine with amikacin resulted in enhanced activity against the two M. abscessus morpho variants compared to treatment with amikacin only. Treatment with cysteamine and cystamine was more effective in reducing GLS size and bacterial load during MAB-S infection compared with MAB-R infection. Moreover, treatment with these two drugs drastically quenched the exuberant proinflammatory response triggered by the MAB-R variant. These findings showing the activity of cysteamine and cystamine against the R and S M. abscessus morphotypes support the use of these drugs as novel host-directed therapies against M. abscessus infections.

Virtual Drug Repositioning as a Tool to Identify Natural Small Molecules That Synergize with Lumacaftor in F508del-CFTR Binding and Rescuing

Cystic fibrosis is a hereditary disease mainly caused by the deletion of the Phe 508 (F508del) of the cystic fibrosis transmembrane conductance regulator (CFTR) protein that is thus withheld in the endoplasmic reticulum and rapidly degraded by the ubiquitin/proteasome system. Cystic fibrosis remains a potentially fatal disease, but it has become treatable as a chronic condition due to some CFTR-rescuing drugs that, when used in combination, increase in their therapeutic effect due to a synergic action. Also, dietary supplementation of natural compounds in combination with approved drugs could represent a promising strategy to further alleviate cystic fibrosis symptoms. On these bases, we screened by in silico drug repositioning 846 small synthetic or natural compounds from the AIFA database to evaluate their capacity to interact with the highly druggable lumacaftor binding site of F508del-CFTR. Among the identified hits, nicotinamide (NAM) was predicted to accommodate into the lumacaftor binding region of F508del-CFTR without competing against the drug but rather stabilizing its binding. The effective capacity of NAM to bind F508del-CFTR in a lumacaftor-uncompetitive manner was then validated experimentally by surface plasmon resonance analysis. Finally, the capacity of NAM to synergize with lumacaftor increasing its CFTR-rescuing activity was demonstrated in cell-based assays. This study suggests the possible identification of natural small molecules devoid of side effects and endowed with the capacity to synergize with drugs currently employed for the treatment of cystic fibrosis, which hopefully will increase the therapeutic efficacy with lower doses.

Changes to the gut microbiota of a wild juvenile passerine in a multidimensional urban mosaic

Urbanisation is a major anthropogenic perturbation presenting novel ecological and evolutionary challenges to wild populations. Symbiotic microorganisms residing in the gastrointestinal tracts (gut) of vertebrates have mutual connections with host physiology and respond quickly to environmental alterations. However, the impact of anthropogenic changes and urbanisation on the gut microbiota remains poorly understood, especially in early development. To address this knowledge gap, we characterised the gut microbiota of juvenile great tits (Parus major) reared in artificial nestboxes and in natural cavities in an urban mosaic, employing two distinct frameworks characterising the urban space. Microbial diversity was influenced by cavity type. Alpha diversity was affected by the amount of impervious surface surrounding the breeding location, and positively correlated with tree cover density. Community composition differed between urban and rural sites: these alterations covaried with sound pollution and distance to the city centre. Overall, the microbial communities reflect and are possibly influenced by the heterogeneous environmental modifications that are typical of the urban space. Strikingly, the choice of framework and environmental variables characterising the urban space can influence the outcomes of such ecological studies. Our results open new perspectives to investigate the impact of microbial symbionts on the adaptive capacity of their hosts.

Sweat metabolomics before and after intravenous antibiotics for pulmonary exacerbation in people with cystic fibrosis

BACKGROUND

People with cystic fibrosis (PWCF) suffer from acute unpredictable reductions in pulmonary function associated with a pulmonary exacerbation (PEx) that may require hospitalization. PEx symptoms vary between PWCF without universal diagnostic criteria for diagnosis and response to treatment.

RESEARCH QUESTION

We characterized sweat metabolomes before and after intravenous (IV) antibiotics in PWCF hospitalized for PEx to determine feasibility and define biological alterations by IV antibiotics for PEx.

STUDY DESIGN AND METHODS

PWCF with PEx requiring hospitalization for IV antibiotics were recruited from clinic. Sweat samples were collected using the Macroduct® Sweat Collection System at admission prior to initiation of IV antibiotics and after completion prior to discharge. Samples were analyzed for metabolite changes using ultra-high-performance liquid chromatography/tandem accurate mass spectrometry.

RESULTS

Twenty-six of 29 hospitalized PWCF completed the entire study. A total of 326 compounds of known identity were detected in sweat samples. Of detected metabolites, 147 were significantly different between pre-initiation and post-completion of IV antibiotics for PEx (average treatment 14 days). Global sweat metabolomes changed from before and after IV antibiotic treatment. We discovered specific metabolite profiles predictive of PEx status as well as enriched biologic pathways associated with PEx. However, metabolomic changes were similar in PWCF who failed to return to baseline pulmonary function and those who did not.

INTERPRETATION

Our findings demonstrate the feasibility of non-invasive sweat metabolomic profiling in PWCF and the potential for sweat metabolomics as a prospective diagnostic and research tool to further advance our understanding of PEx in PWCF.

What role for cysteamine in the defence against infection?

The aminothiol cysteamine has many potential therapeutic applications and is also an endogenous molecule, produced in the body via the activity of pantetheinase enzymes such as vanin-1. This simple small molecule is highly reactive in biological settings and much is yet unknown about its endogenous role in innate immunity to infection, including the impact of cysteamine on bacterial pathogens. We discuss the literature surrounding its biochemistry and challenges to its development as well as the multiple beneficial properties which have been uncovered that support research into its development as novel antimicrobial therapy.

Cysteamine Inhibits Glycine Utilisation and Disrupts Virulence in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a major opportunistic human pathogen which employs a myriad of virulence factors. In people with cystic fibrosis (CF) P. aeruginosa frequently colonises the lungs and becomes a chronic infection that evolves to become less virulent over time, but often adapts to favour persistence in the host with alginate-producing mucoid, slow-growing, and antibiotic resistant phenotypes emerging. Cysteamine is an endogenous aminothiol which has been shown to prevent biofilm formation, reduce phenazine production, and potentiate antibiotic activity against P. aeruginosa, and has been investigated in clinical trials as an adjunct therapy for pulmonary exacerbations of CF. Here we demonstrate (for the first time in a prokaryote) that cysteamine prevents glycine utilisation by P. aeruginosa in common with previously reported activity blocking the glycine cleavage system in human cells. Despite the clear inhibition of glycine metabolism, cysteamine also inhibits hydrogen cyanide (HCN) production by P. aeruginosa, suggesting a direct interference in the regulation of virulence factor synthesis. Cysteamine impaired chemotaxis, lowered pyocyanin, pyoverdine and exopolysaccharide production, and reduced the toxicity of P. aeruginosa secreted factors in a Galleria mellonella infection model. Thus, cysteamine has additional potent anti-virulence properties targeting P. aeruginosa, further supporting its therapeutic potential in CF and other infections.

Innovation in infectious disease therapies from immunology

Antimicrobial therapies developed from immunology, specifically the primary function of the immune system in host defence against microbial pathogens, could offer some of the step-change strategies in drug design and development urgently required to generate much needed, truly novel interventions in infectious disease. The immune system is an as yet underexploited resource of novel molecules and the blueprints for new approaches to combating infection with non-antibiotic, directly antimicrobial strategies.