Engineering zinc oxide hybrid selenium nanoparticles for synergetic anti-tuberculosis treatment by combining Mycobacterium tuberculosis killings and host cell immunological inhibition

Mechanistic Insight into the Anti-Bacterial/Anti-Biofilm Effects of Low Chlorhexidine Concentrations on Enterococcus faecalis-In Vitro Study

BACKGROUND

Endodontic treatment failures are often linked to the persistence of Enterococcus faecalis in the root canal system. This study aimed to investigate the antibacterial/antibiofilm mechanism of chlorhexidine (CHX), particularly at low concentrations, against E. faecalis, to improve endodontic treatment protocols.

METHODS

The antibacterial activity of CHX (0.125-20 μg/mL) was evaluated against E. faecalis ATCC 29212 using various assays, including planktonic growth inhibition, colony-forming units (CFUs), membrane permeability and potential assays, high-resolution scanning electron microscopy (HR-SEM), confocal laser scanning microscopy of biofilms, biomass and metabolic activity assays on matured biofilm, and quantitative real-time PCR for gene expression. Statistical analysis was performed using Student's t-test and ANOVA.

RESULTS

CHX demonstrated concentration-dependent inhibition of E. faecalis, significantly reducing planktonic growth and CFUs. Membrane assays showed increased permeability and depolarization, indicating damage. HR-SEM revealed morphological changes, such as pore formation, while confocal microscopy showed a reduction in biofilm mass and extracellular substances. Gene expression analysis indicated the downregulation of virulence genes and upregulation of stress response genes.

CONCLUSIONS

CHX at low concentrations disrupts E. faecalis at multiple levels, from membrane disruption to gene expression modulation, affecting mature biofilm. These findings support the refinement of endodontic disinfection protocols to reduce microbial persistence.

Nanomaterial-mediated host directed therapy of tuberculosis by manipulating macrophage autophagy

Tuberculosis (TB), induced by Mycobacterium tuberculosis (Mtb) infection, remains a major public health issue worldwide. Mtb has developed complicated strategies to inhibit the immunological clearance of host cells, which significantly promote TB epidemic and weaken the anti-TB treatments. Host-directed therapy (HDT) is a novel approach in the field of anti-infection for overcoming antimicrobial resistance by enhancing the antimicrobial activities of phagocytes through phagosomal maturation, autophagy and antimicrobial peptides. Autophagy, a highly conserved cellular event within eukaryotic cells that is effective against a variety of bacterial infections, has been shown to play a protective role in host defense against Mtb. In recent decades, the introduction of nanomaterials into medical fields open up a new scene for novel therapeutics with enhanced efficiency and safety against different diseases. The active modification of nanomaterials not only allows their attractive targeting effects against the host cells, but also introduce the potential to regulate the host anti-TB immunological mechanisms, such as apoptosis, autophagy or macrophage polarization. In this review, we introduced the mechanisms of host cell autophagy for intracellular Mtb clearance, and how functional nanomaterials regulate autophagy for disease treatment. Moreover, we summarized the recent advances of nanomaterials for autophagy regulations as novel HDT strategies for anti-TB treatment, which may benefit the development of more effective anti-TB treatments.

Photothermal and host immune activated therapy of cutaneous tuberculosis using macrophage targeted mesoporous polydopamine nanoparticles

Tuberculosis (TB) remains the leading cause of deaths among infectious diseases worldwide. Cutaneous Tuberculosis (CTB), caused by Mycobacterium tuberculosis (Mtb) infection in the skin, is still a harmful public health issue that requires more effective treatment strategy. Herein, we introduced mannose-modified mesoporous polydopamine nanosystems (Man-mPDA NPs) as the macrophage-targeted vectors to deliver anti-TB drug rifampicin and as photothermal agent to facilitate photothermal therapy (PTT) against Mtb infected macrophages for synergistic treatment of CTB. Based on the selective macrophage targeting effects, the proposed Rif@Man-mPDA NPs also showed excellent photothermal properties to develop Rif@Man-mPDA NPs-mediated PTT for intracellular Mtb killings in macrophages. Importantly, Rif@Man-mPDA NPs could inhibit the immune escape of Mtb by effectively chelating intracellular Fe2+ and inhibiting lipid peroxidation, and up-regulating GPX4 expression to inhibit ferroptosis of Mtb infected macrophages through activating Nrf2/HO-1 signaling. Moreover, Rif@Man-mPDA NPs-mediated PTT could effectively activate host cell immune responses by promoting autophagy of Mtb infected macrophages, which thus synergizes targeted drug delivery and ferroptosis inhibition for more effective intracellular Mtb clearance. This Rif@Man-mPDA NPs-mediated PTT strategy could also effectively inhibit the Mtb burdens and alleviate the pathological lesions induced by Mtb infection without significant systemic side effects in mouse CTB model. These results indicate that Rif@Man-mPDA NPs-mediated PTT can be served as a novel anti-TB strategy against CTB by synergizing macrophage targeted photothermal therapy and host immune defenses, thus holding promise for more effective treatment strategy development against CTB.

Role of Divalent Cations in Infections in Host-Pathogen Interaction

With increasing numbers of patients worldwide diagnosed with diabetes mellitus, renal disease, and iatrogenic immune deficiencies, an increased understanding of the role of electrolyte interactions in mitigating pathogen virulence is necessary. The levels of divalent cations affect host susceptibility and pathogen survival in persons with relative immune insufficiency. For instance, when host cellular levels of calcium are high compared to magnesium, this relationship contributes to insulin resistance and triples the risk of clinical tuberculosis. The movement of divalent cations within intracellular spaces contributes to the host defense, causing apoptosis or autophagy of the pathogen. The control of divalent cation flow is dependent in part upon the mammalian natural resistance-associated macrophage protein (NRAMP) in the host. Survival of pathogens such as M tuberculosis within the bronchoalveolar macrophage is also dependent upon NRAMP. Pathogens evolve mutations to control the movement of calcium through external and internal channels. The host NRAMP as a metal transporter competes for divalent cations with the pathogen NRAMP in M tuberculosis (whether in latent, dormant, or active phase). This review paper summarizes mechanisms of pathogen offense and patient defense using inflow and efflux through divalent cation channels under the influence of parathyroid hormone vitamin D and calcitonin.

Inulin-Coated ZnO Nanoparticles: A Correlation between Preparation and Properties for Biostimulation Purposes

Within the framework of plant biostimulation, a pivotal role is played by the achievement of low-cost, easily prepared nanoparticles for priming purposes. Therefore, in this report, two different synthetic strategies are described to engineer zinc oxide nanoparticles with an inulin coating. In both protocols, i.e., two-step and gel-like one-pot protocols, nanoparticles with a highly pure ZnO kernel are obtained when the reaction is carried out at T ≥ 40 °C, as ascertained by XRD and ATR/FTIR studies. However, a uniformly dispersed, highly homogeneous coating is achieved primarily when different temperatures, i.e., 60 °C and 40 °C, are employed in the two phases of the step-wise synthesis. In addition, a different binding mechanism, i.e., complexation, occurs in this case. When the gel-like process is employed, a high degree of coverage by the fructan is attained, leading to micrometric coated aggregates of nanometric particles, as revealed by SEM investigations. All NPs from the two-step synthesis feature electronic bandgaps in the 3.25-3.30 eV range in line with previous studies, whereas the extensive coating causes a remarkable 0.4 eV decrease in the bandgap. Overall, the global analysis of the investigations indicates that the samples synthesized at 60 °C and 40 °C are the best suited for biostimulation. Proof-of-principle assays upon Vicia faba seed priming with Zn5 and Zn5@inu indicated an effective growth stimulation of seedlings at doses of 100 mgKg-1, with concomitant Zn accumulation in the leaves.

Biological mechanism of ZnO nanomaterials

Modern nanotechnology has made zinc oxide nanomaterials (ZnO NMts) multifunctional, stable, and low cost, enabling them to be widely used in commercial and biomedical fields. With its wide application, the risk of human direct contact and their release into the environment also increases. This review aims to summarize the toxicity studies of ZnO NMts in vivo, including neurotoxicity, inhalation toxicity, and reproductive toxicity. The antibacterial and antiviral mechanisms of ZnO NMts in vitro and the toxicity to eukaryotic cells were summarized. The summary found that it was mainly related to reactive oxygen species (ROS) produced by oxidative stress. It also discusses the potential harm to body and the favorable prospects of the widespread use of antibacterial and antiviral in the future medical field. The review also emphasizes that the dosage and use method of ZnO NMts will be the focus of future biomedical research.

Macrophage targeted iron oxide nanodecoys augment innate immunological and drug killings for more effective Mycobacterium Tuberculosis clearance

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infection, is still one of the top killers worldwide among infectious diseases. The escape of Mtb from immunological clearance and the low targeting effects of anti-TB drugs remain the substantial challenges for TB control. Iron is particularly required for Mtb growth but also toxic for Mtb in high dosages, which makes iron an ideal toxic decoy for the 'iron-tropic' Mtb. Here, a macrophage-targeted iron oxide nanoparticles (IONPs)-derived IONPs-PAA-PEG-MAN nanodecoy is designed to augment innate immunological and drug killings against intracellular Mtb. IONPs-PAA-PEG-MAN nanodecoy exhibits preferential uptake in macrophages to significantly increase drug uptake with sustained high drug contents in host cells. Moreover, it can serve as a specific nanodecoy for the 'iron-tropic' Mtb to realize the localization of Mtb contained phagosomes surrounding the drug encapsulated nanodecoys and co-localization of Mtb with the drug encapsulated nanodecoys in lysosomes, where the incorporated rifampicin (Rif) can be readily released under acidic lysosomal condition for enhanced Mtb killing. This drug encapsulated nanodecoy can also polarize Mtb infected macrophages into anti-mycobacterial M1 phenotype and enhance M1 macrophage associated pro-inflammatory cytokine (TNF-α) production to trigger innate immunological responses against Mtb. Collectively, Rif@IONPs-PAA-PEG-MAN nanodecoy can synergistically enhance the killing efficiency of intracellular Mtb in in vitro macrophages and ex vivo monocyte-derived macrophages, and also significantly reduce the mycobacterial burdens in the lung of infected mice with alleviated pathology. These results indicate that Rif@IONPs-PAA-PEG-MAN nanodecoy may have a potential for the development of more effective therapeutic strategy against TB by manipulating augmented innate immunity and drug killings.

Nanocarriers in Tuberculosis Treatment: Challenges and Delivery Strategies

The World Health Organization identifies tuberculosis (TB), caused by Mycobacterium tuberculosis, as a leading infectious killer. Although conventional treatments for TB exist, they come with challenges such as a heavy pill regimen, prolonged treatment duration, and a strict schedule, leading to multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. The rise of MDR strains endangers future TB control. Despite these concerns, the hunt for an efficient treatment continues. One breakthrough has been the use of nanotechnology in medicines, presenting a novel approach for TB treatment. Nanocarriers, such as lipid nanoparticles, nanosuspensions, liposomes, and polymeric micelles, facilitate targeted delivery of anti-TB drugs. The benefits of nanocarriers include reduced drug doses, fewer side effects, improved drug solubility, better bioavailability, and improved patient compliance, speeding up recovery. Additionally, nanocarriers can be made even more targeted by linking them with ligands such as mannose or hyaluronic acid. This review explores these innovative TB treatments, including studies on nanocarriers containing anti-TB drugs and related patents.

An Insight into Advances in Developing Nanotechnology Based Therapeutics, Drug Delivery, Diagnostics and Vaccines: Multidimensional Applications in Tuberculosis Disease Management

Tuberculosis (TB), one of the deadliest contagious diseases, is a major concern worldwide. Long-term treatment, a high pill burden, limited compliance, and strict administration schedules are all variables that contribute to the development of MDR and XDR tuberculosis patients. The rise of multidrug-resistant strains and a scarcity of anti-TB medications pose a threat to TB control in the future. As a result, a strong and effective system is required to overcome technological limitations and improve the efficacy of therapeutic medications, which is still a huge problem for pharmacological technology. Nanotechnology offers an interesting opportunity for accurate identification of mycobacterial strains and improved medication treatment possibilities for tuberculosis. Nano medicine in tuberculosis is an emerging research field that provides the possibility of efficient medication delivery using nanoparticles and a decrease in drug dosages and adverse effects to boost patient compliance with therapy and recovery. Due to their fascinating characteristics, this strategy is useful in overcoming the abnormalities associated with traditional therapy and leads to some optimization of the therapeutic impact. It also decreases the dosing frequency and eliminates the problem of low compliance. To develop modern diagnosis techniques, upgraded treatment, and possible prevention of tuberculosis, the nanoparticle-based tests have demonstrated considerable advances. The literature search was conducted using Scopus, PubMed, Google Scholar, and Elsevier databases only. This article examines the possibility of employing nanotechnology for TB diagnosis, nanotechnology-based medicine delivery systems, and prevention for the successful elimination of TB illnesses.