Pleiotropic Effects of Statins: New Therapeutic Approaches to Chronic, Recurrent Infection by Staphylococcus aureus

Repurposing fenticonazole nitrate to restore colistin susceptibility in multidrug-resistant bacteria

AIMS

To explore the synergistic effect of the combination of FN and colistin on Escherichia coli and further elucidate the mechanism of this effect.

MAIN METHODS

Antimicrobial efficacy of the combination of fenticonazole nitrate and colistin against Escherichia coli in vitro using MIC assays, checkerboard assays, growth curves, and time-kill curves. Crystalline violet staining for detection of biofilm. Mechanisms analysis using fluorescence detection, SEM. Analysis of fenticonazole nitrate and MCR-1 interaction using molecular docking and ITC. Finally, the efficacy of combination therapy for MCR-1-positive Escherichia coli was assessed in vivo.

KEY FINDINGS

Fenticonazole nitrate significantly enhanced the ability of colistin to combat mcr-1-positive E. coli 42 in vitro. The combination could effectively inhibit biofilm formation and eradicate established biofilms. Fenticonazole nitrate and colistin could increase the outer membrane permeability of E. coli 42, disrupting the membrane potential and impairing PMF synthesis, which in turn led to a reduction in ATP levels and cell death. Further, we found that the outer membrane barrier of Gram-negative bacteria and the innate resistance mechanism mediated by efflux pumps can impair the antimicrobial activity of fenticonazole nitrate. Finally, the combination demonstrated strong synergistic effects in a mouse model of infection with mcr-1-positive E. coli 42. Compared to the colistin only group, the survival rate increased by 40 %.

CONCLUSION

Fenticonazole nitrate is a promising antibiotic adjuvant against infections caused by MCR-1-positive multidrug-resistant pathogens.

Mechanistic Insights into the Antibiofilm Activity of Simvastatin and Lovastatin against Bacillus subtilis

Statins have been reported for diverse pleiotropic activities, including antimicrobial and antibiofilm. However, due to the limited understanding of their mode of action, none of the statins have gained approval for antimicrobial or antibiofilm applications. In a recent drug repurposing study, we observed that two statins (i.e., Simvastatin and Lovastatin) interact stably with TasA(28-261), the principal extracellular matrix protein of Bacillus subtilis, and also induce inhibition of biofilm formation. Nevertheless, the underlying mechanism remained elusive. In the present study, we examined the impact of these statins on the physiological activity of TasA(28-261), specifically its interaction with TapA(33-253) and aggregation into the amyloid-like structure using purified recombinant TasA(28-261) and TapA(33-253) in amyloid detection-specific in vitro assays (i.e., CR binding and ThT staining assays). Results revealed that both statins interfered with amyloid formation by the TasA(28-261)-TapA(33-253) complex, while neither statin inhibited amyloid formation by lysozyme, a model amyloid-forming protein. Moreover, neither statin significantly altered the expressions of terminal regulatory genes (viz, sinR, sinI) and terminal effector genes (viz, tasA, tapA, and bslA) involved in biofilm formation by B. subtilis. While the intricate interplay between Simvastatin and Lovastatin with the diverse molecular constituents of B. subtilis biofilm remains to be elucidated conclusively, the findings obtained during the present study suggest that the underlying mechanism for Simvastatin- and Lovastatin-mediated inhibition of B. subtilis biofilm formation is manifested by interfering with the aggregation and amyloid formation by TasA(28-261)-TapA(33-253). These results represent one of the first experimental evidence for the underlying mechanism of antibiofilm activity of statins and offer valuable directions for future research to harness statins as antibiofilm therapeutics.

Assessing the Antibacterial Potential and Biofilm Inhibition Capability of Atorvastatin-Loaded Nanostructured Lipid Carriers via Crystal Violet Assay

Background/Objectives: Atorvastatin (ATR), an antihyperlipidemic drug with a potential antibacterial effect, was investigated in this study. Like other statins, ATR has been repurposed for several uses, ranging from anti-inflammatory to antimicrobial applications, and has demonstrated successful results. However, the efficacy of ATR is limited by its low solubility, indicating an opportunity for its encapsulation in a nanotechnology-based drug delivery system. Methods: Nanostructured lipid carrier (NLC) formulations were prepared using high-pressure homogenization and ultrasonication. The formulations were characterized, including their particle size, polydispersity index, zeta potential, encapsulation efficiency, and in vitro release. Antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) was evaluated using the growth curve (bacterial growth over time) and well diffusion methods (zone of inhibition and minimum inhibitory concentration (MIC) determination). The crystal violet assay was employed to assess biofilm inhibition. Results: The NLC formulations were optimized, and the size and zeta potential of the blank nanoparticles were 130 ± 8.39 nm and -35 ± 0.5 mV, respectively. In comparison, the encapsulated NLCs had a size of 142 ± 52.20 nm and a zeta potential of -31 ± 1.41 mV. The average encapsulation efficiency was 94%, and 70% of the drug was released after 24 h. The ATR-loaded NLCs showed significantly enhanced antibacterial activity by reducing the minimum inhibitory concentration by 2.5-fold for E. coli, 1.8-fold for S. aureus, and 1.4-fold for MRSA, and promoting more effective bacterial growth inhibition. Notably, biofilm inhibition was significantly improved with ATR-NLCs, achieving 80% inhibition for S. aureus, 40% for E. coli, and 30% for MRSA, compared to free ATR (p < 0.001). These findings suggest that NLC encapsulation enhances ATR's antimicrobial efficacy and biofilm suppression. Conclusions: This study identified NLCs as successful carriers of ATR, significantly enhancing its antibacterial efficacy and biofilm inhibition capabilities. This formulation, which shows antimicrobial potential against both Gram-positive and Gram-negative bacteria, should be further studied and developed against different resistant microbial strains.

Staphylococcus aureus can use an alternative pathway to be internalized by osteoblasts in absence of β1 integrins

Staphylococcus aureus main internalization mechanism in osteoblasts relies on a tripartite interaction between bacterial fibronectin-binding proteins, extracellular matrix soluble fibronectin, and osteoblasts' β1 integrins. Caveolins, and particularly caveolin-1, have been shown to limit the plasma membrane microdomain mobility, and consequently reduce the uptake of S. aureus in keratinocytes. In this study, we aimed to deepen our understanding of the molecular mechanisms underlying S. aureus internalization in osteoblasts. Mechanistically, S. aureus internalization requires endosomal recycling of β1 integrins as well as downstream effectors such as Src, Rac1, and PAK1. Surprisingly, in β1 integrin deficient osteoblasts, S. aureus internalization is restored when Caveolin-1 is absent and requires αvβ3/5 integrins as backup fibronectin receptors. Altogether, our data support that β1 integrins regulate the level of detergent-resistant membrane at the plasma membrane in a an endosomal and Caveolin-1 dependent manner.

Repurposing simvastatin for treatment of Klebsiella pneumoniae infections: in vitro and in vivo study

Simvastatin had minimum inhibitory concentrations of 32 to 128 µg/mL against Klebsiella pneumoniae isolates and hindered the biofilm-formation ability of 58.54% of the isolates. It considerably diminished the bacterial cell counts in the biofilms as revealed by scanning electron microscope. Also, qRT-PCR revealed a downregulation of the biofilm genes (bcsA, wza, and luxS) by simvastatin in 48.78% of the isolates. Moreover, simvastatin has significantly improved the survival of mice and decreased the burden of bacteria in the infected lungs. Also, the histological architecture was substantially improved in the simvastatin-treated group, as the alveolar sacs and bronchioles appeared normal with minimal collagen fiber deposition. The immunohistochemical studies exposed that the TNF-α, NF-kβ, and COX-2 immunostaining considerably declined in the simvastatin-treated group. Furthermore, ELISA exposed that both IL-1β and IL-6 were considerably diminished in the lungs of the simvastatin-treated group.

Phenotypic Variation in Staphylococcus aureus during Colonisation Involves Antibiotic-Tolerant Cell Types

Staphylococcus aureus is a bacterial species that is commonly found colonising healthy individuals but that presents a paradoxical nature: simultaneously, it can migrate within the body and cause a range of diseases. Many of these become chronic by resisting immune responses, antimicrobial treatment, and medical intervention. In part, this ability to persist can be attributed to the adoption of multiple cell types within a single cellular population. These dynamics in the S. aureus cell population could be the result of its interplay with host cells or other co-colonising bacteria-often coagulase-negative Staphylococcal (CoNS) species. Further understanding of the unique traits of S. aureus alternative cell types, the drivers for their selection or formation during disease, as well as their presence even during non-pathological colonisation could advance the development of diagnostic tools and drugs tailored to target specific cells that are eventually responsible for chronic infections.

Unveiling the Antibacterial Properties of Statins: An In Vitro Study on Helicobacter pylori

Background

Helicobacter pylori (H. pylori), a widespread bacterial pathogen, is associated with various gastrointestinal diseases, including gastric cancer. Statins, widely prescribed cholesterol-lowering agents, have demonstrated pleiotropic effects, including potential antimicrobial properties. This in vitro study investigated the direct antibacterial effects of three clinically approved statins, simvastatin, atorvastatin, and rosuvastatin, against H. pylori isolates.

Methods

H. pylori strains were isolated from gastric biopsies of dyspeptic patients and identified by microbiological techniques. The minimum inhibitory concentrations (MICs) of statins were determined using the agar dilution method, and their antimicrobial activity was evaluated by the disc diffusion method using different concentrations of simvastatin, atorvastatin, rosuvastatin, tetracycline, and amoxicillin. Scanning electron microscopy (SEM) was employed to examine the morphology of H. pylori cells.

Results

The minimum inhibitory concentration (MIC) values (μg/mL) of atorvastatin, rosuvastatin, simvastatin, tetracycline, and amoxicillin against H. pylori were 240 ± 20, 450 ± 20, 460 ± 15, 155 ± 30, and 140 ± 20, respectively. In the disc diffusion assay, atorvastatin and rosuvastatin produced significantly larger inhibition zones compared to simvastatin at all concentrations tested (p < 0.05). The inhibition zone diameters (mm) increased with higher statin concentrations, ranging from 9 ± 1.4 to 13 ± 1.4 for atorvastatin, 8 ± 0.9 to 11 ± 0.6 for rosuvastatin, and 5 ± 1.3 to 6 ± 1.4 for simvastatin at the highest tested concentration (1200 μg/ml). SEM analysis revealed the characteristic spiral morphology of H. pylori cells.

Conclusion

Statins demonstrated varying degrees of antibacterial activity against H. pylori isolates, with atorvastatin exhibiting the highest potency. While the observed effects were lower than those of conventional antibiotics, these findings suggest the potential of statins as adjunctive agents or alternative therapeutic options, warranting further investigation through in vivo studies and clinical trials.

Activation of ARP2/3 and HSP70 Expression by Lipoteichoic Acid: Potential Bidirectional Regulation of Apoptosis in a Mastitis Inflammation Model

Mastitis typically arises from bacterial invasion, where host cell apoptosis significantly contributes to the inflammatory response. Gram-positive bacteria predominantly utilize the virulence factor lipoteichoic acid (LTA), which frequently leads to chronic breast infections, thereby impacting dairy production and animal husbandry adversely. This study employed LTA to develop models of mastitis in cow mammary gland cells and mice. Transcriptomic analysis identified 120 mRNAs associated with endocytosis and apoptosis pathways that were enriched in the LTA-induced inflammation of the Mammary Alveolar Cells-large T antigen (MAC-T), with numerous differential proteins also concentrated in the endocytosis pathway. Notably, actin-related protein 2/3 complex subunit 3 (ARPC3), actin-related protein 2/3 complex subunit 4 (ARPC4), and the heat shock protein 70 (HSP70) are closely related. STRING analysis revealed interactions among ARPC3, ARPC4, and HSP70 with components of the apoptosis pathway. Histological and molecular biological assessments confirmed that ARPC3, ARPC4, and HSP70 were mainly localized to the cell membrane of mammary epithelial cells. ARPC3 and ARPC4 are implicated in the mechanisms of bacterial invasion and the initiation of inflammation. Compared to the control group, the expression levels of these proteins were markedly increased, alongside the significant upregulation of apoptosis-related factors. While HSP70 appears to inhibit apoptosis and alleviate inflammation, its upregulation presents novel research opportunities. In conclusion, we deduced the development mechanism of ARPC3, ARPC4, and HSP70 in breast inflammation, laying the foundation for further exploring the interaction mechanism between the actin-related protein 2/3 (ARP2/3) complex and HSP70.

One Molecule, Many Faces: Repositioning Cardiovascular Agents for Advanced Wound Healing

Chronic wound treatments pose a challenge for healthcare worldwide, particularly for the people in developed countries. Chronic wounds significantly impair quality of life, especially among the elderly. Current research is devoted to novel approaches to wound care by repositioning cardiovascular agents for topical wound treatment. The emerging field of medicinal products' repurposing, which involves redirecting existing pharmaceuticals to new therapeutic uses, is a promising strategy. Recent studies suggest that medicinal products such as sartans, beta-blockers, and statins have unexplored potential, exhibiting multifaceted pharmacological properties that extend beyond their primary indications. The purpose of this review is to analyze the current state of knowledge on the repositioning of cardiovascular agents' use and their molecular mechanisms in the context of wound healing.

Improving the treatment of bacterial infections caused by multidrug-resistant bacteria through drug repositioning

Drug repurposing (repositioning) is a dynamically-developing area in the search for effective therapy of infectious diseases. Repositioning existing drugs with a well-known pharmacological and toxicological profile is an attractive method for quickly discovering new therapeutic indications. The off-label use of drugs for infectious diseases requires much less capital and time, and can hasten progress in the development of new antimicrobial drugs, including antibiotics. The use of drug repositioning in searching for new therapeutic options has brought promising results for many viral infectious diseases, such as Ebola, ZIKA, Dengue, and HCV. This review describes the most favorable results for repositioned drugs for the treatment of bacterial infections. It comprises publications from various databases including PubMed and Web of Science published from 2015 to 2023. The following search keywords/strings were used: drug repositioning and/or repurposing and/or antibacterial activity and/or infectious diseases. Treatment options for infections caused by multidrug-resistant bacteria were taken into account, including methicillin-resistant staphylococci, multidrug-resistant Mycobacterium tuberculosis, or carbapenem-resistant bacteria from the Enterobacteriaceae family. It analyses the safety profiles of the included drugs and their synergistic combinations with antibiotics and discusses the potential of antibacterial drugs with antiparasitic, anticancer, antipsychotic effects, and those used in metabolic diseases. Drug repositioning may be an effective response to public health threats related to the spread of multidrug-resistant bacterial strains and the growing antibiotic resistance of microorganisms.

Don't Judge a Book by Its Cover: The Role of Statins in Liver Cancer

Statins, which are inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, are an effective pharmacological tool for lowering blood cholesterol levels. This property makes statins one of the most popular drugs used primarily to prevent cardiovascular diseases, where hyperlipidemia is a significant risk factor that increases mortality. Nevertheless, studies conducted mainly in the last decade have shown that statins might prevent and treat liver cancer, one of the leading causes of cancer-related mortality worldwide. This narrative review summarizes the scientific achievements to date regarding the role of statins in liver tumors. Molecular biology tools have revealed that cell growth and proliferation can be inhibited by statins, which further inhibit angiogenesis. Clinical studies, supported by meta-analysis, confirm that statins are highly effective in preventing and treating hepatocellular carcinoma and cholangiocarcinoma. However, this effect may depend on the statin's type and dose, and more clinical trials are required to evaluate clinical effects. Moreover, their potential hepatotoxicity is a significant caveat for using statins in clinical practice. Nevertheless, this group of drugs, initially developed to prevent cardiovascular diseases, is now a key candidate in hepato-oncology patient management. The description of new drug-statin-like structures, e.g., with low toxicity to liver cells, may bring another clinically significant improvement to current cancer therapies.

Repositioning of HMG-CoA Reductase Inhibitors as Adjuvants in the Modulation of Efflux Pump-Mediated Bacterial and Tumor Resistance

Efflux pump (EP)-mediated multidrug resistance (MDR) seems ubiquitous in bacterial infections and neoplastic diseases. The diversity and lack of specificity of these efflux mechanisms raise a great obstacle in developing drugs that modulate efflux pumps. Since developing novel chemotherapeutic drugs requires large investments, drug repurposing offers a new approach that can provide alternatives as adjuvants in treating resistant microbial infections and progressive cancerous diseases. Hydroxy-methyl-glutaryl coenzyme-A (HMG-CoA) reductase inhibitors, also known as statins, are promising agents in this respect. Originally, statins were used in the therapy of dyslipidemia and for the prevention of cardiovascular diseases; however, extensive research has recently been performed to elucidate the functions of statins in bacterial infections and cancers. The mevalonate pathway is essential in the posttranslational modification of proteins related to vital eukaryotic cell functions. In this article, a comparative review is given about the possible role of HMG-CoA reductase inhibitors in managing diseases of bacterial and neoplastic origin. Molecular research and clinical studies have proven the justification of statins in this field. Further well-designed clinical trials are urged to clarify the significance of the contribution of statins to the lower risk of disease progression in bacterial infections and cancerous diseases.