The gut microbiota in osteoarthritis: where do we stand and what can we do?

Osteoarthritis (OA) is one of the most frequent musculoskeletal diseases characterized by degeneration of articular cartilage, subchondral bone remodeling, and synovial membrane inflammation, which is a leading cause of global disability, morbidity, and decreased quality of life. Interpreting the potential mechanisms of OA pathogenesis is essential for developing novel prevention and disease-modifying therapeutic interventions. Gut microbiota is responsible for a series of metabolic, immunological, and structural and neurological functions, potentially elucidating the heterogeneity of OA phenotypes and individual features. In this narrative review, we summarized research evidence supporting the hypothesis of a “gut-joint axis” and the interaction between gut microbiota and the OA-relevant factors, including age, gender, genetics, metabolism, central nervous system, and joint injury, elucidating the underlying mechanisms of this intricate interaction. In the context, we also speculated the promising manipulation of gut microbiota in OA management, such as exercise and fecal microbiota transplantation (FMT), highlighting the clinical values of gut microbiota. Additionally, future research directions, such as more convincing studies by the interventions of gut microbiota, the gene regulation of host contributing to or attributed to the specific phenotypes of gut microbiota related to OA, and the relevance of distinct cell subgroups to gut microbiota, are expected. Moreover, gut microbiota is also the potential biomarker related to inflammation and gut dysbiosis that is able to predict OA progression and monitor the efficacy of therapeutic intervention.

The Role of Fibrosis in Osteoarthritis Progression

Osteoarthritis (OA) is a chronic degenerative joint disease where the main characteristics include cartilage degeneration and synovial membrane inflammation. These changes in the knee joint eventually dampen the function of the joint and restrict joint movement, which eventually leads to a stage where total joint replacement is the only treatment option. While much is still unknown about the pathogenesis and progression mechanism of OA, joint fibrosis can be a critical issue for better understanding this disease. Synovial fibrosis and the generation of fibrocartilage are the two main fibrosis-related characteristics that can be found in OA. However, these two processes remain mostly misunderstood. In this review, we focus on the fibrosis process in OA, especially in the cartilage and the synovium tissue, which are the main tissues involved in OA.

Efficacy of intra-articular hyaluronic acid injections in the rehabilitation programme of Knee Osteoarthritis

Knee osteoarthritis (KOA) is a disease of wear and tear, leading to disability and ultimate surgical treatment. KOA has multiple etiologies and is considered a disorder of physiological processes that is manifested by progressive lesions of articular cartilage caused by chondrolysis, synovial membrane inflammation and subchondral osteophytes production. Modalities that limit the progression of the KOA and rehabilitation are a constant interest for clinicians and medical researchers. Various physical therapies and pharmacological strategies are currently used for pain management, with no clear benefit in terms of inhibiting disease progression. In this context, the use of exogenous hyaluronic acid (HA) (that is a vital component of the synovial fluid and involved in lubricating all synovial joints) has been explored as viable alternative to alleviate knee pain and temporarily restore knee function. In the following, we will review the use of HA injections associated with the physiotherapeutic recovery plan in the treatment of KOA. The therapeutic effects of the HA is still a matter of debate in the field, with no consensus being reached so far and thus, difficult to evaluate. However, much research has to be done to understand the therapeutic efficacy of HA alone or in combination with physical therapies and the role that other factors may play in unraveling its beneficial effects on the KOA. Key words: knee, osteoarthritis, hyaluronic acid, physiotherapy, rehabilitation,

Relationship between synovial inflammatory cytokines and progression of osteoarthritis after hip arthroscopy: Experimental assessment

Purpose: Synovial membrane inflammation is the most commonly presenting finding during hip arthroscopy and may have a role in the pathomechanism of hip osteoarthritis (OA). The aim of this study was to determine the relationship between synovial cytokine levels and progression of OA after hip arthroscopy. Methods: We prospectively examined 20 patients (20 hips) who underwent arthroscopic hip surgery. For all patients, radiographs and severity of pain were evaluated preoperatively. During arthroscopy, we harvested a sample of the synovial membrane and determined the levels of six typical inflammatory cytokines with real-time polymerase chain reaction. We compared the levels of these cytokines in patients who showed OA progression and non-progression after hip arthroscopy. Results: Although the average age of patients who showed OA progression postoperatively tended to be higher, there were no significant differences in characteristics involving clinical assessment between patients who showed OA progression and those who showed non-progression. Intraoperative tumour necrosis factor α (TNFα) expression was significantly higher in patients who showed OA progression postoperatively ( p = 0.042). Conclusions: Elevation of TNFα level might be a predictor of OA progression after hip arthroscopy.

Canine osteoarthritis and treatments: a review

Arthritis is a commonly occurring chronic illness in human and animals alike. Among all domestic and pet animal species, dogs suffer from arthritis more often because of excessive running or exercise, injury, and/or genetic predisposition. Presently, one in four of 77.2 million pet dogs in the United States are diagnosed with some form of arthritis. In dogs, osteoarthritis is more common than rheumatoid arthritis and pain is the number one observation. Osteoarthritis, also known as degenerative joint disease, is a slowly progressive inflammatory disease, which is characterized by degeneration of the cartilage, hypertrophy of bone at the margins, and changes in the synovial membrane, and that eventually results in pain and stiffness of joints. Alterations in joint structures, decreased flexibility, and severe pain ensues, due to lack of hydration and inflammation. Cells within the damaged joints release pro-inflammatory cytokines, which further the inflammatory process. This causes more breakdown of the cartilage collagen type II and proteoglycans, which results in a perpetual destructive cycle. This perpetuating cycle ultimately results in cartilage destruction, subchondral bone thickening, and synovial membrane inflammation. This review focuses on osteoarthritis, the disease, causes, treatments, and presents a glimpse of some new therapies under study.

Pneumocystis jiroveciiPneumonia in a Patient with Rheumatoid Arthritis Treated with Abatacept

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial membrane inflammation and joint cartilage destruction. Abatacept is a biologic agent that blocks the costimulation signals, preventing antigen presentation and proliferation of T lymphocytes. It is approved for the treatment of patients with RA.Pneumocystis jiroveciipneumonia (PJP) is an infectious disease complicating several immunosuppressive drugs. PJP associated with abatacept has not been reported yet in the medical literature. Various factors, such as the mechanism of action of abatacept, may contribute to predisposing to Pneumocystis jiroveciiinfection. In this paper, we report a patient with RA who developed PJP under abatacept treatment.