Overcoming Planktonic and Intracellular Staphylococcus aureus-Associated Infection with a Cell-Penetrating Peptide-Conjugated Antimicrobial Peptide

Abstract

Staphylococcus aureus is a primary pathogen responsible for causing postoperative infections as it survives and persists in host cells, including osteoblasts and macrophages. These cells then serve as reservoirs resulting in chronic infections. Most traditional antibiotics have poor effects on intracellular S. aureus because they cannot enter the cell. Herein, a cell-penetrating peptide TAT-KR-12 was derived from the trans-activating transcription (TAT) peptide and KR-12 (residues 18–29 of human cathelicidin LL-37). The TAT acts as a “trojan horse” to deliver KR-12 peptide into the cells to kill S. aureus. Moreover, effective antibacterial properties and biocompatibility were observed in vitro, demonstrating that TAT-KR-12 is effective not only in eliminating planktonic S. aureus, but also in eliminating intracellular S. aureus cells in vitro. TAT-KR-12, as with LL-37, also elicits strong anti-inflammatory activities in LPS-stimulated macrophages, as demonstrated by significant inhibition of NO, TNF-α, and IL-1β expression and secretion from LPS-stimulated RAW264.7 cells. In the subcutaneous infection mouse model of planktonic and intracellular infections, the growth of S. aureus in vivo is evidently inhibited without cytotoxicity. These results suggest that the novel antimicrobial TAT-KR-12 may prove to be an effective treatment option to overcome antibiotic resistance caused by intracellular bacterial infections.

Can intracellular Staphylococcus aureus in osteomyelitis be treated using current antibiotics? A systematic review and narrative synthesis

“…In the studies reviewed, vancomycin was used at higher concentrations than can be expected in the bone but still showed a maximal inhibition effect of a 2-log reduction, independent of the cell type used. 17 , 74 , 125 , 141 , 144 , 162 , 163 It was possible to increase the effect in combination with other agents, such as ansamycins, 146 bacteriophages, 144 peptide-conjugated antimicrobial peptide TAT-KR12 164 or efflux pump inhibitors, 152 but not with liposomes or pegylated liposomes. 163 Interestingly, vancomycin showed increased antimicrobial potency when used after 7 days compared to that at an immediate treatment time.…”

“…For example, it was frequently unclear whether and how extracellular bacteria were removed before treatment. In some studies, the extracellular bacteria were removed before treatment with gentamicin, 54 , 143 , 145 , 152 , 156 , 164 , 166 daptomycin 179 or lysostaphin. 53 , 55 , 58 , 98 , 108 , 126 , 135 , 137 , 142 , 153 , 163 , 178 In other studies, an extracellular bactericidal agent was used during the entire treatment period.…”

Bone infection site targeting nanoparticle-antibiotics delivery vehicle to enhance treatment efficacy of orthopedic implant related infection

“…Determination of the MIC: The MICs against MRSA were investigated as previously described [ 33 ], bacteria in the logarithmic phase of growth were diluted to 1 × 10 6 CFU mL −1 in MHB medium. Thereafter, a two-fold dilution series of NPs, from 1024 μg mL −1 to 1 μg mL −1 , were prepared and plated in a volume of 100 μL in 96-well plates.…”

Antibiotic–cell‐penetrating peptide conjugates targeting challenging drug‐resistant and intracellular pathogenic bacteria

“…Multiple conjugates with truncated and rearranged amino acid sequences displayed good broad-spectrum antibacterial activity against S. aureus, S. epidermidis, S. agalactiae, E. coli, P. aeruginosa, and S. typhimurium with many MICs between 2 and 8 µm, whereas the 1:1 mixture did not show activity against any strains tested. The mechanism of action was determined to be disruption Tat was also investigated as a means to deliver the KR-12 AMP to intracellular locations and kill S. aureus (Huo et al, 2020). KR-12 is the smallest sequence of the LL-37 AMP that maintains the antimicrobial properties of the parent AMP.…”

“…Tat was also investigated as a means to deliver the KR‐12 AMP to intracellular locations and kill S. aureus (Huo et al., 2020). KR‐12 is the smallest sequence of the LL‐37 AMP that maintains the antimicrobial properties of the parent AMP.…”