Tetraspanin profiles of serum extracellular vesicles reflect functional limitations and pain perception in knee osteoarthritis

BACKGROUND

Emerging evidence suggests that extracellular vesicles (EVs) can play roles in inflammatory processes and joint degradation in primary osteoarthritis (OA), a common age-associated joint disease. EV subpopulations express tetraspanins and platelet markers that may reflect OA pathogenesis. The present study investigated the associations between these EV surface markers and articular cartilage degradation, subjectively and objectively assessed pain, and functional limitations in primary knee OA (KOA).

METHODS

Serum EVs were determined by high-sensitivity flow cytometry (large CD61+ EVs) and single particle interferometric reflectance imaging sensor (small CD41+, CD63+, CD81+, and CD9+ EVs) from end-stage KOA patients and controls (n = 8 per group). Knee pain and physical functions were assessed with several health- and pain-related questionnaires, established measurements of physical medicine, and neuromuscular examination. The obtained data were analyzed using supervised and unsupervised univariate and multivariate models.

RESULTS

With the combined dataset of cartilage thickness, knee function, pain, sensation, and EV molecular signatures, we identified highly correlated groups of variables and found several EV markers that were statistically significant predictors of pain, physical limitations, and other aspects of well-being for KOA patients, for instance CD41+/CD63+/CD9+ small EVs associated with the range of motion of the knee, physical performance, and pain sensitivity.

CONCLUSIONS

Particular serum EV subpopulations showed clear associations with KOA pain and functional limitations, suggesting that their implications in OA pathophysiology warrant further study.

Photodynamic Effects with 5-Aminolevulinic Acid on Cytokines and Exosomes in Human Peripheral Blood Mononuclear Cells from Patients with Crohn's Disease

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA) which is the precursor of the photosensitizer protoporphyrin IX (PpIX) is an available treatment for several diseases. ALA-PDT induces the apoptosis and necrosis of target lesions. We have recently reported the effects of ALA-PDT on cytokines and exosomes of human healthy peripheral blood mononuclear cells (PBMCs). This study has investigated the ALA-PDT-mediated effects on PBMC subsets from patients with active Crohn's disease (CD). No effects on lymphocyte survival after ALA-PDT were observed, although the survival of CD3^-/CD19⁺ B-cells seemed slightly reduced in some samples. Interestingly, ALA-PDT clearly killed monocytes. The subcellular levels of cytokines and exosomes associated with inflammation were widely downregulated, which is consistent with our previous findings in PBMCs from healthy human subjects. These results suggest that ALA-PDT may be a potential treatment candidate for CD and other immune-mediated diseases.

Senescence-accelerated mice prone 8 (SAMP8) in male as a spontaneous osteoarthritis model

BACKGROUND

Animal models of spontaneous osteoarthritis (OA) are sparse and not well characterized. The purpose of the present study is to examine OA-related changes and mechanisms in senescence-accelerated mouse prone 8 (SAMP8) that displays a phenotype of accelerated aging.  METHODS: Knees of male SAMP8 and SAM-resistant 1 (SAMR1) mice as control from 6 to 33 weeks of age were evaluated by histological grading systems for joint tissues (cartilage, meniscus, synovium, and subchondral bone), and µCT analysis. Gene expression patterns in articular cartilage were analyzed by real-time PCR. Immunohistochemistry was performed for OA-related factors, senescence markers, and apoptosis.

RESULTS

Starting at 14 weeks of age, SAMP8 exhibited mild OA-like changes such as proteoglycan loss and cartilage fibrillation. From 18 to 33 weeks of age, SAMP8 progressed to partial or full-thickness defects with exposure of subchondral bone on the medial tibia and exhibited synovitis. Histological scoring indicated significantly more severe OA in SAMP8 compared with SAMR1 from 14 weeks [median (interquartile range): SAMR1: 0.89 (0.56-1.81) vs SAMP8: 1.78 (1.35-4.62)] to 33 weeks of age [SAMR1: 1.67 (1.61-1.04) vs SAMP8: 13.03 (12.26-13.57)]. Subchondral bone sclerosis in the medial tibia, bone mineral density (BMD) loss of femoral metaphysis, and meniscus degeneration occurred much earlier than the onset of cartilage degeneration in SAMP8 at 14 weeks of age.

CONCLUSIONS

SAMP8 are a spontaneous OA model that is useful for investigating the pathogenesis of primary OA and evaluating therapeutic interventions.

CD9 Tetraspanin: A New Pathway for the Regulation of Inflammation?

CD9 belongs to the tetraspanin superfamily. Depending on the cell type and associated molecules, CD9 has a wide variety of biological activities such as cell adhesion, motility, metastasis, growth, signal transduction, differentiation, and sperm-egg fusion. This review focuses on CD9 expression by hematopoietic cells and its role in modulating cellular processes involved in the regulation of inflammation. CD9 is functionally very important in many diseases and is involved either in the regulation or in the mediation of the disease. The role of CD9 in various diseases, such as viral and bacterial infections, cancer and chronic lung allograft dysfunction, is discussed. This review focuses also on its interest as a biomarker in diseases. Indeed CD9 is primarily known as a specific exosome marker however, its expression is now recognized as an anti-inflammatory marker of monocytes and macrophages. It was also described as a marker of murine IL-10-competent Breg cells and IL-10-secreting CD9⁺ B cells were associated with better allograft outcome in lung transplant patients, and identified as a new predictive biomarker of long-term survival. In the field of cancer, CD9 was both identified as a favorable prognostic marker or as a predictor of metastatic potential depending on cancer types. Finally, this review discusses strategies to target CD9 as a therapeutic tool. Because CD9 can have opposite effects depending on the situation, the environment and the pathology, modulating CD9 expression or blocking its effects seem to be a new promising therapeutic strategy.