Antiseptic 9-Meric Peptide with Potency against Carbapenem-Resistant Acinetobacter baumannii Infection

Abstract

Carbapenem-resistant A. baumannii (CRAB) infection can cause acute host reactions that lead to high-fatality sepsis, making it important to develop new therapeutic options. Previously, we developed a short 9-meric peptide, Pro9-3D, with significant antibacterial and cytotoxic effects. In this study, we attempted to produce safer peptide antibiotics against CRAB by reversing the parent sequence to generate R-Pro9-3 and R-Pro9-3D. Among the tested peptides, R-Pro9-3D had the most rapid and effective antibacterial activity against Gram-negative bacteria, particularly clinical CRAB isolates. Analyses of antimicrobial mechanisms based on lipopolysaccharide (LPS)-neutralization, LPS binding, and membrane depolarization, as well as SEM ultrastructural investigations, revealed that R-Pro9-3D binds strongly to LPS and impairs the membrane integrity of CRAB by effectively permeabilizing its outer membrane. R-Pro9-3D was also less cytotoxic and had better proteolytic stability than Pro9-3D and killed biofilm forming CRAB. As an LPS-neutralizing peptide, R-Pro9-3D effectively reduced LPS-induced pro-inflammatory cytokine levels in RAW 264.7 cells. The antiseptic abilities of R-Pro9-3D were also investigated using a mouse model of CRAB-induced sepsis, which revealed that R-Pro9-3D reduced multiple organ damage and attenuated systemic infection by acting as an antibacterial and immunosuppressive agent. Thus, R-Pro9-3D displays potential as a novel antiseptic peptide for treating Gram-negative CRAB infections.

Rhamnetin, a Natural Flavonoid, Ameliorates Organ Damage in a Mouse Model of Carbapenem-Resistant Acinetobacter baumannii-Induced Sepsis

“…In this study, we evaluated the antiseptic activity of rhamnetin in an E. coli -induced mouse model of sepsis. 1 mg/kg of rhamnetin was injected 1 h before treating the mice with 3 × 10 5 colony forming unit (CFU) of E. coli, and the efficacy of rhamnetin was analyzed after 16 h. 1 mg/kg concentration was selected based on our previous studies [ 23 , 24 , 32 , 33 ]. Rhamnetin inhibited bacterial growth in vivo, because of which the number of bacteria in the lung, liver, and kidney reduced significantly in the rhamnetin-treated group ( Figure 6 a).…”

“…Peptide therapy offers a novel solution. For instance, R-Pro9-3D, a 9-residue peptide derived from protaetiamycin, exhibits antibacterial and anti-inflammatory activities both in vivo and in vitro against CRAB, demonstrating its effectiveness as an antiseptic peptide [ 32 ]. Additionally, a novel antimicrobial peptide, PapMA-3, depolarized the CRAB membrane and acted synergistically with carbapenem antibiotics [ 33 ].…”

Lights and Shadows of Sepsis Management: Challenges and Future Perspectives

“…Based on the aforementioned knowledge of the mechanisms related to the progression from sepsis to septic shock and the adequate management of patients, including choice and dosages of antimicrobials, the results are crucial to improve outcome of septic patients. Specifically, the manuscripts published in this Special Issue [2][3][4][5][6][7][8] highlighted some important points:…”

“…The review by Krishnan et al [7] focused on sepsis caused by carbapenemase-resistant Acinetobacter baumannii (CRAB), which is responsible for lethal sepsis and high mortality rates in hospital settings. The authors focused on attempting to develop new therapeutic options, such as the development of a novel peptide (R-Pro9-3D) with cytotoxic, antibacterial, and immunosuppressive effects, which act directly on bacterial LPS.…”

Protective Effects of Rhamnetin in Carbapenem-Resistant Acinetobacter baumannii-Induced Sepsis Model and the Underlying Mechanism

“…Plates were incubated at 37 • C for 16 h. Endotoxin levels in the lung lysates were quantified using a Pierce LAL Chromogenic Endotoxin Quantitation Kit (Thermo Fisher Scientific, Waltham, MA, USA), as described previously [58]. The amount of inflammatory cytokines, such as TNF-α, IL-6, IL-1β, and IL-18, in the serum was measured using sandwich ELISA kits (R&D Systems, Minneapolis, MN, USA), as described previously [59].…”