Efficacy of NEMO-binding domain peptide used to treat experimental osteomyelitis caused by methicillin-resistant Staphylococcus aureus: an in-vivo study

Combating bacterial infections with host defense peptides: Shifting focus from bacteria to host immunity

The increasing prevalence of multidrug-resistant bacterial infections necessitates the exploration of novel paradigms for anti-infective therapy. Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), have garnered extensive recognition as immunomodulatory molecules that leverage natural host mechanisms to enhance therapeutic benefits. The unique immune mechanism exhibited by certain HDPs that involves self-assembly into supramolecular nanonets capable of inducing bacterial agglutination and entrapping is significantly important. This process effectively prevents microbial invasion and subsequent dissemination and significantly mitigates selective pressure for the evolution of microbial resistance, highlighting the potential of HDP-based antimicrobial therapy. Recent advancements in this field have focused on developing bio-responsive materials in the form of supramolecular nanonets. A comprehensive overview of the immunomodulatory and bacteria-agglutinating activities of HDPs, along with a discussion on optimization strategies for synthetic derivatives, is presented in this article. These optimized derivatives exhibit improved biological properties and therapeutic potential, making them suitable for future clinical applications as effective anti-infective therapeutics.

Choosing the right animal model for osteomyelitis research: Considerations and challenges

Osteomyelitis is a debilitating bone disorder characterized by an inflammatory process involving the bone marrow, bone cortex, periosteum, and surrounding soft tissue, which can ultimately result in bone destruction. The etiology of osteomyelitis can be infectious, caused by various microorganisms, or noninfectious, such as chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO). Researchers have turned to animal models to study the pathophysiology of osteomyelitis. However, selecting an appropriate animal model that accurately recapitulates the human pathology of osteomyelitis while controlling for multiple variables that influence different clinical presentations remains a significant challenge. In this review, we present an overview of various animal models used in osteomyelitis research, including rodent, rabbit, avian/chicken, porcine, minipig, canine, sheep, and goat models. We discuss the characteristics of each animal model and the corresponding clinical scenarios that can provide a basic rationale for experimental selection. This review highlights the importance of selecting an appropriate animal model for osteomyelitis research to improve the accuracy of the results and facilitate the development of novel treatment and management strategies.

Prophylactic Effects of NFκB Essential Modulator–Binding Domain Peptides on Bone Infection: An Experimental Study in a Rabbit Model

Introduction

Methods

Results

Conclusion

Plate-associated localized osteitis in mini-pig by biofilm-forming Methicillin-resistant Staphylococcus aureus (MRSA): establishment of a novel experimental model

PURPOSE

The increasing number of implant-associated infections during trauma and orthopedic surgery caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance of conventional antibiotics requires new therapeutic strategies. One possibility could be testing for different therapeutic strategies with differently coated plates. Therefore, a clinically realistic model is required. The pig offers the best comparability to the human situation, thus it was chosen for this model. The present study characterizes a novel model of a standardized low-grade acute osteitis with bone defect in the femur in mini-pigs, which is stabilized by a titanium locking plate to enable further studies with various coatings.

METHODS

A bone defect was performed on the femur of 7 Aachen mini-pigs and infected with Methicillin-resistant S. aureus (MRSA ATCC 33592). The defect zone was stabilized with a titanium plate. After 14 days, a plate change, wound debridement and lavage were performed. Finally, after 42 days, the animals were lavaged and debrided again, followed by euthanasia. The fracture healing was evaluated radiologically and histologically.

RESULTS

A local osteitis with radiologically visible lysis of the bone could be established. The unchanged high Colony-forming Units (CFU) in lavage, the significant differences in Interleukin (IL)-6 in blood compared to lavage and the lack of increase in Alkaline Phosphates (ALP) in serum over the entire observation period show the constant local infection.

CONCLUSION

The study shows the successful induction of local osteitis with lysis of the bone and the lack of enzymatic activity to mineralize the bone. Therefore, this standardized mini-pig model can be used in further clinical studies, to investigate various coated implants, bone healing, biofilm formation and immune response in implant-associated osteitis.

Recent advances in design and applications of biomimetic self-assembled peptide hydrogels for hard tissue regeneration

Abstract

The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance, especially in societies with a large elderly population. Self-assembled peptide hydrogels are a new generation of biomaterials that provide excellent biocompatibility, tunable mechanical stability, injectability, trigger capability, lack of immunogenic reactions, and the ability to load cells and active pharmaceutical agents for tissue regeneration. Peptide-based hydrogels are ideal templates for the deposition of hydroxyapatite crystals, which can mimic the extracellular matrix. Thus, peptide-based hydrogels enhance hard tissue repair and regeneration compared to conventional methods. This review presents three major self-assembled peptide hydrogels with potential application for bone and dental tissue regeneration, including ionic self-complementary peptides, amphiphilic (surfactant-like) peptides, and triple-helix (collagen-like) peptides. Special attention is given to the main bioactive peptides, the role and importance of self-assembled peptide hydrogels, and a brief overview on molecular simulation of self-assembled peptide hydrogels applied for bone and dental tissue engineering and regeneration.

Graphic abstract

High Mycoplasma pneumoniae loads and persistent long-term Mycoplasma pneumoniae DNA in lower airway associated with severity of pediatric Mycoplasma pneumoniae pneumonia

Background

An increased number of refractory mycoplasma pneumoniae (MP) pneumonia (MPP) cases have been reported. However the duration of MP infection in lower airway and the course of anti-MP treatment remains unclear.

Methods

We retrospectively reviewed the medical records of 94 MPP children. Patients were classified into two groups. The long-term group (Group LT) was defined as bronchoalveolar lavage fluid (BALF) remained MP-positive by PCR after 30 days of the disease course. The non-long-term group (Group NLT) was defined as BALF became MP-negative by PCR within 30 days of disease and patients who only needed one bronchoscopy lavage therapy. MP loads, clinical outcomes were analyzed along with other clinical measurements.

Results

The average levels of inflammatory markers such as C reactive protein and lactate dehydrogenase in Group LT were significantly higher than those in Group NLT. Airway and lung damage in Group LT were more severe than Group NLT. 28 patients developed necrotizing pneumonia and 8 patients developed pulmonary embolism in Group LT. Mean maximum MP loads in BALF were 10^{7.46 ± 0.93} and 10^{4.86 ± 0.93} in Groups LT and NLT, respectively. There was persistent MP DNA in Group LT, even lasted for 120 days. One severe MPP patient in Group LT had MP-associated bloodstream infection. After 3 months of follow-up, chest imaging revealed incomplete absorption of pulmonary consolidation in 33 patients of Group LT [including 13 airway obliterans (AO) patients] and in 7 patients of Group NLT (including 2 AO patients).

Conclusion

MP loads of BALF were associated with the subsequent duration of MP DNA in lower airway. High MP loads and persistent long-term MP DNA in lower airway were associated with severity of pediatric MPP.