In vitro modelling of bacterial pneumonia: a comparative analysis of widely applied complex cell culture models.

Bacterial pneumonia greatly contributes to the disease burden and mortality of lower respiratory tract infections among all age groups and risk profiles. Therefore, laboratory modelling of bacterial pneumonia remains important for elucidating the complex host-pathogen interactions and to determine drug efficacy and toxicity. In vitro cell culture enables for the creation of high-throughput, specific disease models in a tightly controlled environment. Advanced human cell culture models specifically, can bridge the research gap between the classical two-dimensional cell models and animal models. This review provides an overview of the current status of the development of complex cellular in vitro models to study bacterial pneumonia infections, with a focus on air-liquid interface models, spheroid, organoid, and lung-on-a-chip models. For the wide scale, comparative literature search, we selected six clinically highly relevant bacteria (Pseudomonas aeruginosa, Mycoplasma pneumoniae, Haemophilus influenzae, Mycobacterium tuberculosis, Streptococcus pneumoniae, and Staphylococcus aureus). We reviewed the cell lines that are commonly used, as well as trends and discrepancies in the methodology, ranging from cell infection parameters to assay read-outs. We also highlighted the importance of model validation and data transparency in guiding the research field towards more complex infection models.

All Eyes on the Prefusion-Stabilized F Construct, but Are We Missing the Potential of Alternative Targets for Respiratory Syncytial Virus Vaccine Design?

Respiratory Syncytial Virus (RSV) poses a significant global health concern as a major cause of lower respiratory tract infections (LRTIs). Over the last few years, substantial efforts have been directed towards developing vaccines and therapeutics to combat RSV, leading to a diverse landscape of vaccine candidates. Notably, two vaccines targeting the elderly and the first maternal vaccine have recently been approved. The majority of the vaccines and vaccine candidates rely solely on a prefusion-stabilized conformation known for its highly neutralizing epitopes. Although, so far, this antigen design appears to be successful for the elderly, our current understanding remains incomplete, requiring further improvement and refinement in this field. Pediatric vaccines still have a long journey ahead, and we must ensure that vaccines currently entering the market do not lose efficacy due to the emergence of mutations in RSV's circulating strains. This review will provide an overview of the current status of vaccine designs and what to focus on in the future. Further research into antigen design is essential, including the exploration of the potential of alternative RSV proteins to address these challenges and pave the way for the development of novel and effective vaccines, especially in the pediatric population.

The Liebeskind-Srogl Cross-Coupling Reaction as a Crucial Step in the Synthesis of New Squaramide-Based Antituberculosis Agents.

The synthesis of an extensive series of new squaramides with high potential in treating drug-resistant tuberculosis employing the Liebeskind-Srogl cross-coupling reaction is presented. Using the protocol given and various substrates, we assessed the scope and limitations of our methodology and prepared an extensive range of desired compounds. Moreover, 1H NMR spectra in solution show the presence of two rotational conformers (rotamers) in special cases. The results of antimycobacterial activity demonstrate the highly selective substrate specificity of the tested squaramides, requiring an efficient and widely applicable synthetic approach needed for the discovery of lead compounds. Our synthetic strategy confirms the versatility of squaramides that can be easily transformed into diverse functionalized molecules.

A high-throughput target-based screening approach for the identification and assessment of Mycobacterium tuberculosis mycothione reductase inhibitors.

The World Health Organization's goal to combat tuberculosis (TB) is hindered by the emergence of anti-microbial resistance, therefore necessitating the exploration of new drug targets. Multidrug regimens are indispensable in TB therapy as they provide synergetic bactericidal effects, shorten treatment duration, and reduce the risk of resistance development. The research within our European RespiriTB consortium explores Mycobacterium tuberculosis energy metabolism to identify new drug candidates that synergize with bedaquiline, with the aim of discovering more efficient combination drug regimens. In this study, we describe the development and validation of a luminescence-coupled, target-based assay for the identification of novel compounds inhibiting Mycobacterium tuberculosis mycothione reductase (MtrMtb), an enzyme with a role in the protection against oxidative stress. Recombinant MtrMtb was employed for the development of a highly sensitive, robust high-throughput screening (HTS) assay by coupling enzyme activity to a bioluminescent readout. Its application in a semi-automated setting resulted in the screening of a diverse library of ~130,000 compounds, from which 19 hits were retained after an assessment of their potency, selectivity, and specificity. The selected hits formed two clusters and four fragment molecules, which were further evaluated in whole-cell and intracellular infection assays. The established HTS discovery pipeline offers an opportunity to deliver novel MtrMtb inhibitors and lays the foundation for future efforts in developing robust biochemical assays for the identification and triaging of inhibitors from high-throughput library screens. IMPORTANCE: The growing anti-microbial resistance poses a global public health threat, impeding progress toward eradicating tuberculosis. Despite decades of active research, there is still a dire need for the discovery of drugs with novel modes of action and exploration of combination drug regimens. Within the European RespiriTB consortium, we explore Mycobacterium tuberculosis energy metabolism to identify new drug candidates that synergize with bedaquiline, with the aim of discovering more efficient combination drug regimens. In this study, we present the development of a high-throughput screening pipeline that led to the identification of M. tuberculosis mycothione reductase inhibitors.

Ensayo de citotoxicidad de extractos de Pleurotusostreatus en diferentes líneas celulares para aplicaciones inmunonutricionales / Cytotoxicity assay of Pleurotus ostreatusextracts in different cell lines to immunonutritional applications / Cytotoxicity assay of Pleurotus ostreatusextracts in different cell lines to immunonutritional applications / Ensaio de citotoxicidade de extratos de Pleurotus ostreatus em diferentes linhagens celulares para aplicações imunonutricionais

Introducción: Los bioderivados propuestos como candidatos a ingredientes alimentarios suelen requerir ciertas evaluaciones para las aplicaciones inmunonutricionales Los hongos comestibles-medicinales son un surtidor de compuestos con estas potencialidades. Entre ellos, las setas Pleurotus ostreatus contienen metabolitos bioactivos, con importantes usos en la industria alimenticia y en la práctica terapéutica de la industria médico-farmacéutica. Los ensayos de citotoxicidad in vitro constituyen métodos valiosos para evaluarproductos de origen natural, como los extractos fúngicos. Objetivo: Evaluar la citotoxicidad de dos extractos obtenidos de la seta Pleurotus ostreatus en diferentes líneas celulares. Método: Se obtuvieron extractos hidrosolubles a partir del micelio y de los cuerpos fructíferos de Pleurotus ostreatus en laboratorios del Centro de Estudios de Biotecnología Industrial de la Universidad de Oriente. Se evaluó la citotoxicidad de los bioproductos por el ensayo de reducción del colorante resazurina sobre tres líneas celulares en el Laboratorio de Microbiología, Parasitología e Higiene (LMPH) de la Universidad de Amberes, Bélgica. Se utilizaron células no adherentes THP-1 (pre-monocitos de leucemia humana), células adherentes Caco-2 (epitelio de adenocarcinoma de colon humano) y células adherentes RAW 264.7 (macrófagos murinos). Resultados: Los extractos de Pleurotus ostreatus no resultaron citotóxicos para ninguna de las líneas celulares estudiadas humanas o murina, ya que no ocasionaron daños sobre la viabilidad de las célulasepiteliales del sistema gastrointestinal, nisobrelas células del sistema inmune empleadas. Conclusiones: Este resultado demuestra que ambos bioderivados fúngicos pueden ser aplicados con seguridad en estudios inmunonutricionales.(AU)

Introduction: Bioderivatives proposed as candidates for food ingredients usually require certain evaluations for immunonutritional applications. Edible-medicinal mushrooms are a source of compounds with these potentials. Among them, Pleurotus ostreatus mushrooms contain bioactive metabolites, with important uses in the food industry and in the therapeutic practice of the medical-pharmaceutical industry. In vitro cytotoxicity assays are valuable methods to evaluate products of natural origin, such as fungal extracts. Objective: To evaluate the cytotoxicity of two extracts obtained from the Pleurotus ostreatus mushroom in different cell lines. Method: Water-soluble extracts were obtained from the mycelium and fruiting bodies of Pleurotus ostreatus in laboratories of the Center for Industrial Biotechnology Studies of the Universidad de Oriente. The cytotoxicity of the bioproducts was evaluated by the resazurin dye reduction assay on three cell lines at the Laboratory of Microbiology, Parasitology and Hygiene (LMPH) of the University of Antwerp, Belgium. Non-adherent THP-1 cells (human leukemia pre-monocytes), Caco-2 adherent cells (human colon adenocarcinoma epithelium) and RAW 264.7 adherent cells (murine macrophages) were used. Results: Pleurotus ostreatus extracts were not cytotoxic for any of the human or murine cell lines studied, since they did not cause damage to the viability of the epithelial cells of the gastrointestinal system, nor to the immune system cells used. Conclusions: This result demonstrates that both fungal bioderivatives can be safely applied in immunonutritional studies.(AU)

Introdução: Bioderivados propostos como candidatos a ingredientes alimentícios geralmente requerem determinadas avaliações para aplicações imunonutricionais. Pleurotus ostreatus contêm metabólitos bioativos, com importantes utilizações na indústria alimentícia e na prática terapêutica da indústria médico-farmacêutica. Ensaios de citotoxicidade in vitro são métodos valiosos para avaliar produtos de origem natural, como extratos de fungos. Objetivo: Avaliar a citotoxicidade de dois extratos obtidos do cogumelo Pleurotus ostreatus em diferentes linhagens celulares. Método: Extratos hidrossolúveis foram obtidos do micélio e dos corpos frutíferos de Pleurotus ostreatus nos laboratórios do Centro de Estudos de Biotecnologia Industrial da Universidade de Oriente. A citotoxicidade dos bioprodutos foi avaliada pelo ensaio de redução do corante resazurina em três linhagens celulares no Laboratório de Microbiologia, Parasitologia e Higiene (LMPH) da Universidade de Antuérpia, Bélgica. Foram utilizadas células THP-1 não aderentes (pré-monócitos de leucemia humana), células aderentes Caco-2 (epitélio de adenocarcinoma do cólon humano) e células aderentes RAW 264.7 (macrófagos murinos). Resultados: Os extratos de Pleurotus ostreatus não foram citotóxicos para nenhuma das linhagens celulares humanas ou murinas estudadas, pois não causaram danos à viabilidade das células epiteliais do sistema gastrointestinal, nem às células do sistema imunológico utilizadas. Conclusões: Este resultado demonstra que ambos os bioderivados fúngicos podem ser aplicados com segurança em estudos imunonutricionais.(AU)

In vitro antimicrobial assessment of Cuban propolis extracts

Propolis is a resinous mixture of different plant exudates collected by honeybees. Currently, propolis is widely used as a food supplement and in folk medicine. We have evaluated 20 Cuban propolis extracts of different chemical types, brown (BCP), red and yellow (YCP), with respect to their in vitro antibacterial, antifungal and antiprotozoal properties. The extracts inhibited the growth of Staphylococcus aureus and Trichophyton rubrum at low µg/mL concentrations, whereas they were not active against Escherichia coli and Candida albicans. The major activity of the extracts was found against the protozoa Leishmania, Trypanosoma and Plasmodium, although cytotoxicity against MRC-5 cells was also observed. The BCP-3, YCP-39 and YCP-60 extracts showed the highest activity against P. falciparum, with 50% of microbial growth (IC50) values of 0.2 µg/mL. A positive correlation between the biological activity and the chemical composition was observed for YCP extracts. The most promising antimicrobial activity corresponds to YCP subtype B, which contains acetyl triterpenes as the main constituents. The present in vitro study highlights the potential of propolis against protozoa, but further research is needed to increase selectivity towards the parasite. The observed chemical composition-activity relationship of propolis can contribute to the identification of the active principles and standardisation of this bee product.

In vitro anti-microbial activity of the Cuban medicinal plants Simarouba glauca DC, Melaleuca leucadendron L and Artemisia absinthium L

In the present study, an extensive in vitro antimicrobial profiling was performed for three medicinal plants grown in Cuba, namely Simarouba glauca, Melaleuca leucadendron and Artemisia absinthium. Ethanol extracts were tested for their antiprotozoal potential against Trypanosoma b. brucei, Trypanosoma cruzi, Leishmania infantum and Plasmodium falciparum. Antifungal activities were evaluated against Microsporum canis and Candida albicans whereas Escherichia coli and Staphylococcus aureus were used as test organisms for antibacterial activity. Cytotoxicity was assessed against human MRC-5 cells. Only M. leucadendron extract showed selective activity against microorganisms tested. Although S. glauca exhibited strong activity against all protozoa, it must be considered non-specific. The value of integrated evaluation of extracts with particular reference to selectivity is discussed.