Systemic application of bone-targeting peptidoglycan hydrolases as a novel treatment approach for staphylococcal bone infection

The rising prevalence of antimicrobial resistance in S. aureus has rendered treatment of staphylococcal infections increasingly difficult, making the discovery of alternative treatment options a high priority. Peptidoglycan hydrolases, a diverse group of bacteriolytic enzymes, show high promise as such alternatives due to their rapid and specific lysis of bacterial cells, independent of antibiotic resistance profiles. However, using these enzymes for the systemic treatment of local infections, such as osteomyelitis foci, needs improvement, as the therapeutic distributes throughout the whole host, resulting in low concentrations at the actual infection site. In addition, the occurrence of intracellularly persisting bacteria can lead to relapsing infections. Here, we describe an approach using tissue-targeting to increase the local concentration of therapeutic enzymes in the infected bone. The enzymes were modified with a short targeting moiety that mediated accumulation of the therapeutic in osteoblasts and additionally enables targeting of intracellularly surviving bacteria

Higher levels of neurofilament light chain and total tau in CSF are associated with negative outcome after shunt surgery in patients with normal pressure hydrocephalus

Background: Lumbar punctures are a common examination in the work-up of patients with idiopathic normal pressure hydrocephalus (iNPH) and cerebrospinal fluid (CSF) biomarkers should therefore be available for use in selection of shunt candidates. The aim of this study was to investigate if CSF biomarkers are associated with outcome after shunt surgery alone or in combination with comorbidity and imaging markers, and investigate associations between CSF biomarkers and symptoms Methods: Preoperative CSF biomarkers were analyzed in 455 patients operated with shunt surgery for iNPH at a single center during 2011–2018. Symptoms before and 12 months after shunt surgery were graded with the Swedish iNPH scale. Neurofilament light chain protein (NfL), total tau (T-tau), phosphorylated tau (P-tau) and amyloid beta1-42 (Aβ1-42) CSF levels were measured. Evans’ index and disproportionately enlarged subarachnoid space hydrocephalus were measured on preoperative CT-scans. Preoperative evaluation and follow-up 12 months after shunt surgery were available in 376 patients. Result: Higher levels of NfL and T-tau were associated with less improvement after shunt surgery (β = − 3.10, p = 0.016 and β = − 2.45, p = 0.012, respectively). Patients whose symptoms deteriorated after shunt surgery had higher preoperative levels of NfL (1250 ng/L [IQR:1020–2220] vs. 1020 [770–1649], p < 0.001) and T-tau (221 ng/L [IQR: 159–346] vs. 190 [135–261], p = 0.0039) than patients with postoperative improvement on the iNPH scale. Among the patients who improved ≥ 5 levels on the iNPH scale (55%), NfL was abnormal in 22%, T-tau in 14%, P-tau in 6% and Aβ1-42 in 45%, compared with normal reference limits. The inclusion of CSF biomarkers, imaging markers and comorbidity in multivariate predictive Orthogonal Projections to Latent Structures (OPLS) models to did not improve predictability in outcome after shunt surgery. Conclusions: Higher levels of T-tau and NfL were associated with a less favorable response to shunt surgery, suggesting a more active neurodegeneration in this group of patients. However, CSF levels of these biomarkers can be elevated also in patients who respond to shunt surgery. Thus, none of these CSF biomarkers, alone or used in combination, are suitable for excluding patients from surgery

Systemic application of bone-targeting peptidoglycan hydrolases as a novel treatment approach for staphylococcal bone infection

The current standard of treatment for chronic staphylococcal osteomyelitis entails high doses of antibiotics over the course of several weeks. Biofilm-associated and intracellular persisters are key factors contributing to therapeutic failure. Additionally, systemic application results in low concentrations of antibiotics at local infection sites due to its general distribution throughout the host. In this study, we explored a targeted approach for the treatment of staphylococcal osteomyelitis, employing a combination of highly active peptidoglycan hydrolases (PGHs) and cell-penetrating homing peptides (CPHPs) with specificity for osteoblasts. In vitro phage display on murine osteoblasts followed by next-generation sequencing led to the identification of 10 putative cell-penetrating homing peptides, which subsequently showed cell-line specific internalization of covalently linked fluorescent molecules into murine osteoblasts. Upon intravenous application, the lead candidate peptide mediated tissue-specific accumulation of an associated PGH in murine bones, confirming its function as an osteotropic peptide with cell-penetrating abilities. Furthermore, we selected three enzymes with high staphylolytic activity in murine serum screened from a set of 28 PGHs highly active against Staphylococcus aureus in human serum and under intracellular conditions: lysostaphin (LST), M23LST(L)_SH3b2638, and CHAPGH15_SH3bAle1. Finally, we demonstrated increased efficacy of the three PGHs modified with two osteotropic CPHPs as compared to their unmodified parentals at reducing bacterial numbers in a murine model of S. aureus deep wound subcutaneous infection leading to dissemination to the bone. Collectively, our findings show that modification of PGHs with tissue-specific CPHPs presents a viable approach for the systemic treatment of localized infections associated with intracellular bacteria.ISSN:2150-7511ISSN:2161-212