Integrin-dependent recruitment of Src to ROS-producing endosomes in osteoarthritic cartilage

Quantum sensing to monitor changes in free radical generation by intracellular vesicles of polarized macrophages

Macrophages are immune cells crucial in clearing our tissues from bacteria, viruses, dying cells, cell debris and other waste products. They also regulate inflammation by differentiating from non-activated (M0) cells into macrophages that initiate inflammation (pro-inflammatory macrophages, M1), or resolve inflammation (anti-inflammatory macrophages, M2). One of their key functions is to ingest pathogens within vesicles where they are degraded. The production of free radical (FR) plays an important role in this degradation process but also in macrophage differentiation and signaling. Here we used diamond-based quantum sensing to track free radical changes in vesicles with nanoscale resolution. We further followed the oxidative stress status, through free radical measurement during the macrophage activation process. We found that the three macrophage subtypes differed significantly in free radical generation in their vesicles. Additionally, we showed that the FR generation evolves over time in the different subtypes. We observed a 50 % increase in radical production in M0 after 24 h compared to the T1 values measured after 4 h of cell culture, a decrease in M1 and constant radical levels in M2 macrophages. STATEMENT OF SIGNIFICANCE: Here we use quantum sensing for the first time to investigate the role that free radicals play in immune cells when they differentiate to fulfill their functions in the immune system. We were able to measure free radical generation specifically in vesicles while the macrophages differentiated.

Matrikine stimulation of equine synovial fibroblasts and chondrocytes results in an in vitro osteoarthritis phenotype

Osteoarthritis (OA) is a debilitating disease that impacts millions of individuals and has limited therapeutic options. A significant hindrance to therapeutic discovery is the lack of in vitro OA models that translate reliably to in vivo preclinical animal models. An alternative to traditional inflammatory cytokine models is the matrikine stimulation model, in which fragments of matrix proteins naturally found in OA tissues and synovial fluid, are used to stimulate cells of the joint. The objective of this study was to determine if matrikine stimulation of equine synovial fibroblasts and chondrocytes with fibronectin fragments (FN7-10) would result in an OA phenotype. We hypothesized that FN7-10 stimulation of equine articular cells would result in an OA phenotype with gene and protein expression changes similar to those previously described for human chondrocytes stimulated with FN7-10. Synovial fibroblasts and chondrocytes isolated from four horses were stimulated in monolayer culture for 6 or 18 h with 1 µM purified recombinant 42 kD FN7-10 in serum-free media. At the conclusion of stimulation, RNA was collected for targeted gene expression analysis and media for targeted protein production analysis. Consistent with our hypothesis, FN7-10 stimulation resulted in significant alterations to many important genes that are involved in OA pathogenesis including increased expression of IL-1β, IL-4, IL-6, CCL2/MCP-1, CCL5/RANTES, CXCL6/GCP-2, MMP-1, MMP-3, and MMP13. The results of this study suggest that the equine matrikine stimulation model of OA may prove useful for in vitro experiments leading up to preclinical trials.

Wharton's Jelly Mesenchymal Stem Cells: Shaping the Future of Osteoarthritis Therapy with Advancements in Chitosan-Hyaluronic Acid Scaffolds

This review explores the potential of Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) in cartilage regeneration and osteoarthritis treatment. It covers key factors influencing chondrogenesis, including growth factors, cytokines, and hypoxia, focusing on precise timing. The effectiveness of three-dimensional cultures and scaffold-based strategies in chondrogenic differentiation is discussed. Specific biomaterials such as chitosan and hyaluronic acid are highlighted for tissue engineering. The document reviews clinical applications, incorporating evidence from animal research and early trials and molecular and histological assessments of chondrogenic differentiation processes. It addresses challenges and strategies for optimizing MSC-derived chondrocyte therapy, emphasizing the immunomodulatory properties of these cells. The review concludes as a comprehensive road map for future research and clinical applications in regenerative medicine.

Pharmacological inactivation of a non-canonical gp130 signaling arm attenuates chronic systemic inflammation and multimorbidity induced by a high-fat diet

Interleukin-6 (IL-6) is a major pro-inflammatory cytokine that demonstrates a robust correlation with age and body mass index (BMI) as part of the senescence-associated secretory phenotype. IL-6 cytokines also play a crucial role in metabolic homeostasis and regenerative processes primarily via the canonical STAT3 pathway. Thus, selective modulation of IL-6 signaling may offer a unique opportunity for therapeutic interventions. Our recent studies identified a novel non-canonical signaling pathway that involves prolonged activation of SRC family of kinases (SFKs) by IL-6/gp130, where genetic or pharmacological inhibition of this pathway was protective in several acute injury models. This study was designed to assess the effect of a small molecule (R159) that inhibits the non-canonical signaling in a mouse model of multimorbidity induced by chronic inflammation. Aged mice were fed a high-fat diet (HFD) to exacerbate chronic inflammation and inflammaging-related conditions, and R159 significantly decreased systemic inflammatory responses in adipose tissue and liver. R159 was protective against trabecular bone and articular cartilage loss and markedly prevented neurogenesis decline. Moreover, R159 reduced weight gain induced by HFD and increased physical activity levels. These findings suggest that selective pharmacological inhibition of SFK signaling downstream of IL6/gp130 offers a promising strategy to alleviate systemic chronic inflammation and relevant multimorbidity.

A synthetic bioactive peptide of the C-terminal fragment of adhesion protein Fibulin7 attenuates the inflammatory functions of innate immune cells in LPS-induced systemic inflammation

OBJECTIVE

Systemic inflammation is associated with improper localization of hyperactive neutrophils and monocytes in visceral organs. Previously, a C-terminal fragment of adhesion protein Fibulin7 (Fbln7-C) was shown to regulate innate immune functionality during inflammation. Recently, a shorter bioactive peptide of Fbln7-C, FC-10, via integrin binding was shown to reduce ocular angiogenesis. However, the role of FC-10 in regulating the neutrophils and monocyte functionality during systemic inflammatory conditions is unknown. The study sought to explore the role of FC-10 peptide on the functionality of innate immune cells during inflammation and endotoxemic mice.

METHODS

Neutrophils and monocytes were isolated from healthy donors and septic patient clinical samples and Cell adhesion assay was performed using a UV spectrophotometer. Gene expression studies were performed using qPCR. Protein level expression was measured using ELISA and flow cytometry. ROS assay, and activation markers analysis in vitro, and in vivo were done using flow cytometry.

TREATMENT

Cells were stimulated with LPS (100 ng/mL) and studied in the presence of peptides (10 μg, and 20 μg/mL) in vitro. In an in vivo study, mice were administered with LPS (36.8 mg/kg bw) and peptide (20 μg).

RESULTS

This study demonstrates that human neutrophils and monocytes adhere to FC-10 via integrin β1, inhibit spreading, ROS, surface activation markers (CD44, CD69), phosphorylated Src kinase, pro-inflammatory genes, and protein expression, compared to scrambled peptide in cells isolated from healthy donors and clinical sample. In line with the in vitro data, FC-10 (20 μg) administration significantly decreases innate cell infiltration at inflammatory sites, improves survival in endotoxemia animals & reduces the inflammatory properties of neutrophils and monocytes isolated from septic patients.

CONCLUSION

FC-10 peptide can regulate neutrophils and monocyte functions and has potential to be used as an immunomodulatory therapeutic in inflammatory diseases.

Application of Antioxidant Compounds in Bone Defect Repair

Bone defects caused by trauma, tumor resection, and infections are significant clinical challenges. Excessive reactive oxygen species (ROS) usually accumulate in the defect area, which may impair the function of cells involved in bone formation, posing a serious challenge for bone repair. Due to the potent ROS scavenging ability, as well as potential anti-inflammatory and immunomodulatory activities, antioxidants play an indispensable role in the maintenance and protection of bone health and have gained increasing attention in recent years. This narrative review aims to give an overview of the main research directions on the application of antioxidant compounds in bone defect repair over the past decade. In addition, the positive effects of various antioxidants and their biomaterial delivery systems in bone repair are summarized to provide new insights for exploring antioxidant-based strategies for bone defect repair.

Inactivation of a non-canonical gp130 signaling arm attenuates chronic systemic inflammation and multimorbidity induced by a high-fat diet

Interleukin-6 (IL-6) is a major pro-inflammatory cytokine for which the levels in plasma demonstrate a robust correlation with age and body mass index (BMI) as part of the senescence-associated secretory phenotype. IL-6 cytokines also play a crucial role in metabolic homeostasis and regenerative processes, primarily via the canonical STAT3 pathway. Thus, selective modulation of IL-6 signaling may offer a unique opportunity for therapeutic interventions. Recently, we discovered that a non-canonical signaling pathway downstream of tyrosine (Y) 814 within the intracellular domain of gp130, the IL-6 co-receptor, is responsible for the recruitment and activation of SRC family of kinases (SFK). Mice with constitutive genetic inactivation of gp130 Y814 (F814 mice) show accelerated resolution of inflammatory response and superior regenerative outcomes in skin wound healing and posttraumatic models of osteoarthritis. The current study was designed to explore if selective genetic or pharmacological inhibition of the non-canonical gp130-Y814/SFK signaling reduces systemic chronic inflammation and multimorbidity in a high-fat diet (HFD)-induced model of accelerated aging. F814 mice showed significantly reduced inflammatory response to HFD in adipose and liver tissue, with significantly reduced levels of systemic inflammation compared to wild type mice. F814 mice were also protected from HFD-induced bone loss and cartilage degeneration. Pharmacological inhibition of gp130-Y814/SFK in mice on HFD mirrored the effects observed in F814 mice on HFD; furthermore, this pharmacological treatment also demonstrated a marked increase in physical activity levels and protective effects against inflammation-associated suppression of neurogenesis in the brain tissue compared to the control group. These findings suggest that selective inhibition of SFK signaling downstream of gp130 receptor represents a promising strategy to alleviate systemic chronic inflammation. Increased degenerative changes and tissue senescence are inevitable in obese and aged organisms, but we demonstrated that the systemic response and inflammation-associated multi-morbidity can be therapeutically mitigated.