Delivery by Dendritic Mesoporous Silica Nanoparticles Enhances the Antimicrobial Activity of a Napsin‐Derived Peptide Against Intracellular Mycobacterium tuberculosis

Abstract

Tuberculosis remains a serious global health problem causing 1.3 million deaths annually. The causative pathogen Mycobacterium tuberculosis (Mtb) has developed several mechanisms to evade the immune system and resistances to many conventional antibiotics, so that alternative treatment strategies are urgently needed. By isolation from bronchoalveolar lavage and peptide optimization, a new antimicrobial peptide named NapFab is discovered. While showing robust activity against extracellular Mtb, the activity of NapFab against intracellular bacteria is limited due to low intracellular availability. By loading NapFab onto dendritic mesoporous silica nanoparticles (DMSN) as a carrier system, cellular uptake, and consequently antimycobacterial activity against intracellular Mtb is significantly enhanced. Furthermore, using lattice light-sheet fluorescence microscopy, it can be shown that the peptide is gradually released from the DMSN inside living macrophages over time. By electron microscopy and tomography, it is demonstrated that peptide loaded DMSN are stored in vesicular structures in proximity to mycobacterial phagosomes inside the cells, but the nanoparticles are typically not in direct contact with the bacteria. Based on the combination of functional and live-cell imaging analyses, it is hypothesized that after being released from the DMSN NapFab is able to enter the bacterial phagosome and gain access to the bacilli.

Gran1: A Granulysin-Derived Peptide with Potent Activity against Intracellular Mycobacterium tuberculosis

“…We exposed embryos for 24 h, starting at 24 h post fertilization (hpf), when most organ systems have already developed and are functional. Transparency of the embryos allows for the evaluation, not only of mortality, but also of sublethal cytotoxicity (necrosis, lysis), developmental toxicity (developmental delay, malformations), or toxicity affecting specific organ systems, in particular cardiotoxicity (heart edema, reduced circulation) and neurotoxicity (reduced touch escape response), as mentioned in prior studies [20,21]. Gran1 neither effected embryo viability nor caused sublethal toxicity (Figure 4E).…”

“…Embryos were categorized within each of these toxicity categories into several classes of severity. Chi-square test was used to calculate whether the distribution of embryos into toxicity classes [21] differed significantly between the negative control and the test substances.…”

Antimicrobial peptide-based materials: opportunities and challenges

“…11C). 253 Similarly, MSNs loaded with NZX 256 and NapFab 257 AMPs also showed potent antituberculosis properties in vitro (against Mycobacterium bovis , M. bovis (BCG)) and in vivo (against M. tuberculosis H37Rv). Sharma et al designed Pep-H AMP, identified from human neutrophil peptide-1, and conjugated on chitosan and Au NPs.…”

“…E. coli and Enterococcus faecalis ( E. faecalis ) are most prevalent bacteria in UTIs. 257 Generally, the antimicrobial activity of conjugated AMPs is compromised due to protein adsorption or biofilm formation on the top of the AMP-coated surfaces. This challenge can be overcome by modifying the physicochemical properties of catheters such as wettability and surface charge.…”

Nanoantibiotics Based in Mesoporous Silica Nanoparticles: New Formulations for Bacterial Infection Treatment

“…Active targeting provides nanosystems of specificity to the site of infection, being relevant in the case of intracellular infections, where bacteria overcome the host immune system by surviving in human cells. In this sense, MSNs have already been used as nanocarriers of anti-tuberculosis drugs [81,82], silver [83] or antimicrobial peptides [84] as antimycobacterial agents against intracellular Mycobacterium tuberculosis, the pathogen responsible for tuberculosis. This section describes recent advances in the pursuit of MSNs at the two main targets concerning infection management, the bacterium and the biofilm.…”