Sphingolipid-Induced Bone Regulation and Its Emerging Role in Dysfunction Due to Disease and Infection.

The human skeleton is a metabolically active system that is constantly regenerating via the tightly regulated and highly coordinated processes of bone resorption and formation. Emerging evidence reveals fascinating new insights into the role of sphingolipids, including sphingomyelin, sphingosine, ceramide, and sphingosine-1-phosphate, in bone homeostasis. Sphingolipids are a major class of highly bioactive lipids able to activate distinct protein targets including, lipases, phosphatases, and kinases, thereby conferring distinct cellular functions beyond energy metabolism. Lipids are known to contribute to the progression of chronic inflammation, and notably, an increase in bone marrow adiposity parallel to elevated bone loss is observed in most pathological bone conditions, including aging, rheumatoid arthritis, osteoarthritis, and osteomyelitis. Of the numerous classes of lipids that form, sphingolipids are considered among the most deleterious. This review highlights the important primary role of sphingolipids in bone homeostasis and how dysregulation of these bioactive metabolites appears central to many chronic bone-related diseases. Further, their contribution to the invasion, virulence, and colonization of both viral and bacterial host cell infections is also discussed. Many unmet clinical needs remain, and data to date suggest the future use of sphingolipid-targeted therapy to regulate bone dysfunction due to a variety of diseases or infection are highly promising. However, deciphering the biochemical and molecular mechanisms of this diverse and extremely complex sphingolipidome, both in terms of bone health and disease, is considered the next frontier in the field.

Extracellular Proteins Isolated from L. acidophilus as an Osteomicrobiological Therapeutic Agent to Reduce Pathogenic Biofilm Formation, Regulate Chronic Inflammation, and Augment Bone Formation In Vitro.

Periprosthetic joint infection (PJI) is a challenging complication that can occur following joint replacement surgery. Efficacious strategies to prevent and treat PJI and its recurrence remain elusive. Commensal bacteria within the gut convey beneficial effects through a defense strategy named "colonization resistance" thereby preventing pathogenic infection along the intestinal surface. This blueprint may be applicable to PJI. The aim is to investigate Lactobacillus acidophilus spp. and their isolated extracellular-derived proteins (LaEPs) on PJI-relevant Staphylococcus aureus, methicillin-resistant S. aureus, and Escherichia coli planktonic growth and biofilm formation in vitro. The effect of LaEPs on cultured macrophages and osteogenic, and adipogenic human bone marrow-derived mesenchymal stem cell differentiation is analyzed. Data show electrostatically-induced probiotic-pathogen species co-aggregation and pathogenic growth inhibition together with LaEP-induced biofilm prevention. LaEPs prime macrophages for enhanced microbial phagocytosis via cathepsin K, reduce lipopolysaccharide-induced DNA damage and receptor activator nuclear factor-kappa B ligand expression, and promote a reparative M2 macrophage morphology under chronic inflammatory conditions. LaEPs also significantly augment bone deposition while abating adipogenesis thus holding promise as a potential multimodal therapeutic strategy. Proteomic analyses highlight high abundance of lysyl endopeptidase, and urocanate reductase. Further, in vivo analyses are warranted to elucidate their role in the prevention and treatment of PJIs.

Positive Correlation Between Social Media Utilization by Orthopaedic Journals and Impact Factor.

INTRODUCTION: Social media use has exploded in popularity over the past decade with over 1.5 billion users on Facebook and 320 million users on Twitter. The aim of this study was to analyze the use of social media by orthopaedic journals and determine whether a relationship exists between social media followers and journal impact factor. METHODS: The Clarivate Analytics Impact Factor tool was used to identify all orthopaedic journals with a 2022 impact factor of greater than 1.5. We then conducted a query on Instagram, Twitter, LinkedIn, and Facebook to determine which programs had pages on each platform. RESULTS: Seventeen journals were included across all orthopaedic subspecialties. Of the 17 journals, 14 (82.4%) had a Facebook page, eight (47%) had an Instagram page, 15 (88.2%) had a Twitter account, and 8 (47%) had a LinkedIn profile. When compiling the number of followers by social media platform, Twitter had the most (177,543), followed by Facebook (149,388), Instagram (81,739), and LinkedIn (77,459). We found a significant correlation between the number of social media followers and journal impact factor (Pearson correlation coefficient [PCC] = 0.67; P = 0.003). When analyzing each social media platform independently, we found a significant correlation between the number of Facebook and Twitter followers and journal impact factor (PCC = 0.54; P = 0.02 and PCC = 0.80; P < 0.001, respectively). DISCUSSION: We have shown a notable association between the number of social media followers and a journal's impact factor. With the increasing shift toward online distribution, orthopaedic journals may use our data when evaluating their social media strategy to maintain and potentially increase their exposure and potentially their impact factor.