Intestinal microbiome composition and its relation to joint pain and inflammation

Links between short-chain fatty acids and osteoarthritis from pathology to clinic via gut-joint axis

Short-chain fatty acids (SCFAs), the primary metabolites produced by the microbial fermentation of dietary fibers in the gut, have a key role in protecting gut health. Increasing evidence indicates SCFAs can exert effects on distant tissues and organs beyond the gut via blood circulation. Osteoarthritis (OA) is a chronic inflammatory joint disease that severely diminishes the physical function and quality of life. However, effective clinical treatments for OA remain elusive. Recent studies have shown that SCFAs can exert beneficial effects on damaged joints in OA. SCFAs can mitigate OA progression by preserving intestinal barrier function and maintaining the integrity of cartilage and subchondral bone, suggesting that they have substantial potential to be the adjunctive treatment strategy for OA. This review described the SCFAs in the human body and their cellular signaling mechanism, and summarized the multiple effects of SCFAs (especially butyrate, propionate, and acetate) on the prevention and treatment of OA by regulating the gut-joint axis, providing novel insights into their promising clinical applications.

Effect of electroacupuncture combined with Tuina therapy on gut microbiota in patients with knee osteoarthritis

BACKGROUND

Knee osteoarthritis (KOA) is a chronic condition characterized by joint pain and dysfunction, driven by aging and obesity. Research indicates that the gut microbiota significantly influences KOA, potentially affecting inflammation and disease progression through the gut-joint axis. Traditional treatments like non-steroidal anti-inflammatory drugs offer symptom relief but have adverse effects. Emerging therapies like electroacupuncture (EA) and Tuina (TN) have shown promise in alleviating pain and improving joint function by targeting the gut microbiota.

AIM

To clarify the efficacy of EA with TN in treating KOA and its effect on gut microbiota regulation.

METHODS

Sixty patients with KOA were allocated to EA or EA + TN (ET) group (n = 30 each). Seven acupoints were punctured. The ET group received TN after each EA session. Both groups completed 12 sessions. The visual analog scale (VAS) for assessing pain and the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) for measuring pain intensity, joint stiffness, and functional capacity were employed to assess clinical outcomes. Pre- and post-treatment fecal specimens underwent 16S ribosomal RNA sequencing to analyze the gut microbiota.

RESULTS

The ET group showed higher rates of “effective” and “markedly effective” outcomes. The VAS score of the ET group remained significantly lower than that of the EA group (P < 0.001) immediately after treatment and 1 week post-treatment. The total WOMAC score (P < 0.001), pain (P = 0.191), stiffness (P = 0.015), and function scores (P < 0.001) decreased significantly in the ET group post-treatment. The gut microbiota analysis revealed no significant changes in alpha diversity in either group. Beta-diversity analysis indicated distinct patterns in the ET group before and after treatment. Significant changes in microbial abundance were detected in both groups, highlighting variations in Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes.

CONCLUSION

ET outperforms EA alone in improving KOA pain, stiffness, and function, potentially via gut microbiota modulation, intestinal barrier protection, and inflammation reduction.

Gut Microbiota: A Modulator and Therapeutic Target for Chronic Pain

Chronic pain is a prevalent condition, impacting nearly one-fifth of the global population. Despite the availability of various clinical treatments, each comes with inherent limitations, and few offer a complete cure, resulting in a significant social and economic burden. Therefore, it is important to determine the pathogenesis and causes of chronic pain. Numerous studies have shown a close link between the intestinal microflora and chronic pain. The gut microbiota can exert their effects on chronic pain through both central and peripheral mechanisms and is able to communicate with the brain through its own components or metabolites. They also can regulate chronic pain by affecting pro- and anti-inflammatory cells. This review is aimed at reviewing the connection between gut flora and different types of chronic pain, including visceral pain, neuropathic pain, inflammatory pain, musculoskeletal pain, migraine, and chronic cancer pain; exploring the central and peripheral mechanisms of the influence of gut flora on chronic pain; and attempting to provide novel treatment options for chronic pain, that is, the gut microbiota can be regulated by probiotics, fecal microbial transplantation, and natural products to treat chronic pain. By examining the intricate relationship between gut flora and chronic pain, the review sought to pave the way for new treatment strategies that target the gut microbiota, offering hope for more effective pain management.

Gut and Joint Microbiomes: Implications in Osteoarthritis

This review summarizes and discusses key recent findings suggesting that microbiomes can play a role in the development and progression of osteoarthritis. Evidence supporting a gut microbiome-joint connection derived from human and animal studies is enumerated and discussed, with particular attention on the microbial and molecular basis for the development of therapeutic interventions that involve targeting the gut. Additionally, clinical data supporting the concept of a living microbiome within a diarthrodial joint are summarized. A discussion of key limitations in the current data and important technical considerations for firmly establishing the existence of a synovial joint microbial community is included.

Osteoarthritis treatment via the GLP-1-mediated gut-joint axis targets intestinal FXR signaling

Whether a gut-joint axis exists to regulate osteoarthritis is unknown. In two independent cohorts, we identified altered microbial bile acid metabolism with reduced glycoursodeoxycholic acid (GUDCA) in osteoarthritis. Suppressing farnesoid X receptor (FXR)-the receptor of GUDCA-alleviated osteoarthritis through intestine-secreted glucagon-like peptide 1 (GLP-1) in mice. GLP-1 receptor blockade attenuated these effects, whereas GLP-1 receptor activation mitigated osteoarthritis. Osteoarthritis patients exhibited a lower relative abundance of Clostridium bolteae, which promoted the formation of ursodeoxycholic acid (UDCA), a precursor of GUDCA. Treatment with C. bolteae and Food and Drug Administration-approved UDCA alleviated osteoarthritis through the gut FXR-joint GLP-1 axis in mice. UDCA use was associated with lower risk of osteoarthritis-related joint replacement in humans. These findings suggest that orchestrating the gut microbiota-GUDCA-intestinal FXR-GLP-1-joint pathway offers a potential strategy for osteoarthritis treatment.

Efficacy and safety of loxoprofen sodium cataplasms in the treatment of osteoarthritis: A randomized, multicenter study

The present study aimed to compare the efficacy and safety of loxoprofen sodium cataplasm (LSC) with those of flurbiprofen cataplasm (FPC) in osteoarthritis (OA) treatment. In this multicenter, randomized controlled trial, subjects meeting the inclusion and exclusion criteria were randomly assigned to the two treatment groups. According to the manufacturer's instructions, the first group received LSC once daily, with the application of one patch per area for 2 weeks, whereas the second group received FPC twice daily, with the application of one patch per area for 2 weeks. The treatment response was evaluated based on the Visual Analog Scale (VAS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) global score, Lysholm score and adverse events for 296 patients enrolled across three subcenters, with 192 patients in the LSC group and 104 patients in the FPC group. The treatment effectiveness rates, based on the VAS, WOMAC global and Lysholm scores, were 74.46, 61.41 and 85.25%, respectively, for the LSC group and 43.14, 31.37 and 66.67%, respectively, for the FPC group. Regardless of the effectiveness criterion used, the LSC group exhibited a superior treatment effectiveness rate compared with the FPC group. After 2 weeks of treatment, OA symptoms improved in both groups, with the LSC group exhibiting lower VAS (P<0.05) and WOMAC global scores (comprising pain, stiffness and physical function scores) compared with the FPC group (P<0.05), while the Lysholm score was higher in the LSC group compared with the FPC group (P<0.05). The FPC group experienced more general adverse events (P>0.05) and dressing shedding (P<0.05) compared with the LSC group, whereas the LSC group had more specific adverse events (such as skin itching, fever and allergy) compared with the FPC group (P>0.05). The results suggested that compared with FPC, LSC exhibited higher short-term efficacy and a consistent safety profile. The present study was registered at Chinese Clinical Trial Register (chictr.org.cn; ChiCTR2300072504; date of registration, June 15, 2023).

The role of the immune system in osteoarthritis: mechanisms, challenges and future directions

Osteoarthritis (OA) is a chronic joint disease that has long been considered a simple wear-and-tear condition. Over the past decade, research has revealed that various inflammatory features of OA, such as low-grade peripheral inflammation and synovitis, contribute substantially to the pathophysiology of the disease. Technological advances in the past 5 years have revealed a large diversity of innate and adaptive immune cells in the joints, particularly in the synovium and infrapatellar fat pad. Notably, the presence of synovial lymphoid structures, circulating autoantibodies and alterations in memory T cell and B cell populations have been documented in OA. These data indicate a potential contribution of self-reactivity to the disease pathogenesis, blurring the often narrow and inaccurate line between chronic inflammatory and autoimmune diseases. The diverse immune changes associated with OA pathogenesis can vary across disease phenotypes, and a better characterization of their underlying molecular endotypes will be key to stratifying patients, designing novel therapeutic approaches and ultimately ameliorating treatment allocation. Furthermore, examining both articular and systemic alterations, including changes in the gut-joint axis and microbial dysbiosis, could open up novel avenues for OA management.

The Gut Microbiome and Joint Microbiome Show Alterations in Patients With Knee Osteoarthritis Versus Controls: A Systematic Review

PURPOSE

To assess the current scientific literature on the microbiome's relation with knee osteoarthritis (OA), with specific focuses on the gut microbiome-joint axis and joint microbiome-joint axis.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines; the PubMed, Embase, and Cochrane databases were searched for relevant English-language clinical studies on the gut and/or joint microbiomes' association with knee OA in humans. Bias was evaluated using the Methodological Index for Non-randomized Studies score.

RESULTS

Thirty-five thousand bacterial species comprise the gut microbiome; approximately 90% are members of the phyla Bacteroides and Firmicutes. Symbiosis between the gut microbiome and host under normal physiological conditions positively affects host growth, development, immunity, and longevity. Gut microbiome imbalance can negatively influence various physiological processes, including immune response, inflammation, metabolism, and joint health including the development of knee OA. In addition, next-generation gene sequencing suggests the presence of microorganisms in the synovial fluid of OA knees, and distinct microbiome profiles detected are presumed to play a role in the development of OA. Regarding the gut microbiome, consistent alterations in microbial composition between OA patients and controls are noted, in addition to several associations between certain gut bacteria and OA-related knee pain, patient-reported outcome measure performance, imaging findings, and changes in metabolic and inflammatory pathways. Regarding the joint microbiome, studies have revealed that increased levels of lipopolysaccharide and lipopolysaccharide-binding protein in synovial fluid are associated with activated macrophages-and are correlated with worsened osteophyte severity, joint space narrowing, and pain scores in knee OA patients. In addition, studies have shown various microbial composition differences in OA patients compared with controls, with certain joint microbes directly associated with OA pathogenesis, inflammation, and metabolic dysregulation.

CONCLUSIONS

The gut microbiome-joint axis and joint microbiome show alterations in microbial composition between patients with OA and controls. These alterations are associated with perturbations of metabolic and inflammatory pathways, imaging findings, OA-related pain, and patient-reported outcome measure performance.

LEVEL OF EVIDENCE

Level III, systematic review of Level II and III studies.

A Mendelian randomization study to reveal gut-disc axis: causal associations between gut microbiota with intervertebral disc diseases

PURPOSE

Emerging evidence suggests a link between gut microbiota and intervertebral disc diseases (IDDs); however, the causal relationships remain unclear. This study aimed to evaluate the causal effects of gut microbiota on the risk of cervical disc disorders (CDD), other intervertebral disc disorders (OIDD), pyogenic intervertebral disc infections, and discitis, shedding light on the potential "gut-disc axis".

METHODS

Genetic variation data for 202 gut microbiota taxa were obtained from the Dutch Microbiome Project, and disease outcome data were sourced from the FinnGen consortium. A Mendelian Randomization (MR) approach was employed to assess causal relationships, using genetic variants as instrumental variables. Sensitivity analyses, including tests for pleiotropy, heterogeneity, and reverse causation, ensured robust findings.

RESULTS

The study identified 20 gut microbial taxa with significant associations to IDDs. Notably, taxa within the Erysipelotrichaceae family showed consistent protective effects against OIDD after Bonferroni correction (P < 0.05). Associations between several species and specific diseases, such as Alistipes senegalensis with CDD and Ruminococcus lactaris with discitis, were also observed. Sensitivity analyses confirmed no evidence of confounding or reverse causation.

CONCLUSION

This study provides evidence of causal relationships between specific gut microbiota and IDDs, supporting the existence of a "gut-disc axis." The findings suggest that microbial dysbiosis may influence spinal health through systemic inflammation and immune regulation. These insights open new possibilities for microbiota-targeted interventions, such as probiotics or dietary modifications, to prevent or manage IDDs. However, further research is required to validate these therapeutic strategies.

Serum intestinal permeability biomarkers are associated with erosive hand osteoarthritis and radiographic severity: results from the DIGICOD cohort

OBJECTIVE

To investigate the association between intestinal permeability alteration and erosive hand osteoarthritis (EHOA).

METHODS

Serum concentrations of four intestinal permeability biomarkers (lipopolysaccharide binding protein (LBP), FABP2, sCD14, Zonulin-related proteins (ZRP) along with calprotectin, and high-sensitivity C-Reactive Protein (hs-CRP) were assessed in 410 patients of the DIGICOD cohort. The study compared patients with EHOA (≥ 2 erosion in Verbruggen score N=140) to those without EHOA (N=270) using the Mann-Whitney U test. Logistic regression was performed to adjust for potential covariates. The Spearman rank test was used to investigate the correlation between intestinal permeability biomarkers and seven clinical variables associated with HOA clinical and radiographic severity.

RESULTS

Serum levels of LBP and ZRP were found to be higher in patients with EHOA compared to those without EHOA (p=0.001, p=0.04). Additionally, LBP and ZRP remained associated with EHOA in a logistic regression model adjusted for age, body mass index, and sex (p=0.017, p=0.005). ZRP was positively correlated with Verbruggen score and Kellgren-Lawrence sum score of both hands (r=0.14 p=0.005, r=0.12 p=0.023). LBP was positively correlated with the number of erosive joints (r=0.14 p=0.0006). Hs-CRP and LBP were positively correlated with AUSCAN pain (r=0.14 p=0.008, r=0.10 p=0.042).

CONCLUSIONS

LBP and ZRP were associated with EHOA with clinical and radiographic severity in HOA. These results overall support the role of intestinal permeability in both symptoms and structural alteration in HOA.

Dissecting Causal Relationships Between Gut Microbiota, 1400 Blood Metabolites, and Intervertebral Disc Degeneration

OBJECTIVE

The precise mechanisms driving intervertebral disc degeneration (IVDD) development remain unclear, but evidence suggests a significant involvement of gut microbiota (GM) and blood metabolites. We aimed to investigate the causal relationships between GM, IVDD, and blood metabolites using Mendelian randomization (MR) analysis.

METHODS

We utilized the summary statistics of GM from the MiBioGen consortium, 1400 blood metabolites from the genome-wide association studies (GWAS) Catalog, and IVDD data from the FinnGen repository, which are sourced from the largest GWAS conducted to date. Employing bidirectional MR analyses, we investigated the causal relationships between GM and IVDD. Additionally, we conducted 2 mediation analyses, 2-step MR and multivariable MR (MVMR), to identify potential mediating metabolites.

RESULTS

Five bacterial genera were causally associated with IVDD, while IVDD did not show a significant causal effect on GM. In the 2-step MR analysis, Eubacteriumfissicatenagroup, RuminococcaceaeUCG003, Lachnoclostridium, and Marvinbryantia genera, along with metabolites X-24949, Pimeloylcarnitine/3-methyladipoylcarnitine (C7-DC), X-24456, histidine, 2-methylserine, Phosphocholine, and N-delta-acetylornithine, were all significantly associated with IVDD (all p < 0.05). MVMR analysis revealed that the associations between Eubacteriumfissicatenagroup genus and IVDD were mediated by X-24949 (8.1%, p = 0.024); Lachnoclostridium genus and IVDD were mediated by histidine (18.1%, p = 0.013); and RuminococcaceaeUCG003 genus and IVDD were mediated by C7-DC (-7.5%, p = 0.041).

CONCLUSION

The present MR study offers evidence supporting the causal relationships between several specific GM taxa and IVDD, as well as identifying potential mediating metabolites.

Osteoarthritis

Osteoarthritis is a heterogeneous whole-joint disease that can cause pain and is a leading cause of disability and premature work loss. The predominant disease risk factors - obesity and joint injury - are well recognized and modifiable. A greater understanding of the complex mechanisms, including inflammatory, metabolic and post-traumatic processes, that can lead to disease and of the pathophysiology of pain is helping to delineate mechanistic targets. Currently, management is primarily focused on alleviating the main symptoms of pain and obstructed function through lifestyle interventions such as self-management programmes, education, physical activity, exercise and weight management. However, lack of adherence to known effective osteoarthritis therapeutic strategies also contributes to the high global disease burden. For those who have persistent symptoms that are compromising quality of life and have not responded adequately to core treatments, joint replacement is an option to consider. The burden imparted by the disease causes a substantial impact on individuals affected in terms of quality of life. For society, this disease is a substantial driver of increased health-care costs and underemployment. This Primer highlights advances and controversies in osteoarthritis, drawing key insights from the current evidence base.

Innovations in acute and chronic pain biomarkers: enhancing diagnosis and personalized therapy

Pain affects millions worldwide, posing significant challenges in diagnosis and treatment. Despite advances in understanding pain mechanisms, there remains a critical need for validated biomarkers to enhance diagnosis, prognostication, and personalized therapy. This review synthesizes recent advancements in identifying and validating acute and chronic pain biomarkers, including imaging, molecular, sensory, and neurophysiological approaches. We emphasize the emergence of composite, multimodal strategies that integrate psychosocial factors to improve the precision and applicability of biomarkers in chronic pain management. Neuroimaging techniques like MRI and positron emission tomography provide insights into structural and functional abnormalities related to pain, while electrophysiological methods like electroencepholography and magnetoencepholography assess dysfunctional processing in the pain neuroaxis. Molecular biomarkers, including cytokines, proteomics, and metabolites, offer diagnostic and prognostic potential, though extensive validation is needed. Integrating these biomarkers with psychosocial factors into clinical practice can revolutionize pain management by enabling personalized treatment strategies, improving patient outcomes, and potentially reducing healthcare costs. Future directions include the development of composite biomarker signatures, advances in artificial intelligence, and biomarker signature integration into clinical decision support systems. Rigorous validation and standardization efforts are also necessary to ensure these biomarkers are clinically useful. Large-scale collaborative research will be vital to driving progress in this field and implementing these biomarkers in clinical practice. This comprehensive review highlights the potential of biomarkers to transform acute and chronic pain management, offering hope for improved diagnosis, treatment personalization, and patient outcomes.

Inflammaging contributes to osteoarthritis development and human microbiota variations and vice versa: A systematic review

OBJECTIVE

To report evidence on microbiota and its relationship with inflammaging, the innate immune system and osteoarthritis (OA) in human patients.

DESIGN

A systematic review was performed in accordance with PRISMA and following the PICO model. Web of Science, Scopus, Cochrane Library for clinical trials and PubMed were searched. The analysis was focused on human OA patients, and the outcome was mainly microbiota identification, improvement or deterioration of OA pain, stiffness or inflammation.

RESULTS

After screening, 24 studies fulfilled the inclusion criteria. There is not a standardised procedure yet, as microbiota analysis in OA is relatively new. The 16S rRNA gene is the most used in bacterial phylogeny and taxonomy studies as it is highly conserved. Selected articles hypothesise about the correlation between the altered composition of the gut microbiota and OA severity, which seems to affect the immune composition by disrupting gut permeability and releasing pro-inflammatory factors. Five preliminary clinical trials used pro-prebiotics to treat OA patients, and although their results are not conclusive and the methodology needs to be improved, it might indicate a favourable approach for further studies in the prevention of OA.

CONCLUSIONS

Several hypotheses have been made on the associations between microbiota changes and inflammation. They mainly advocate that those changes in the gastrointestinal tract affect gut permeability, which alters the immune system, leading to OA progression. Research advances, along with the continual growth and improvement of technology, mark this 'microbiota-inflammaging-OA' axis as a promising line of investigation.

The gut microbiome and osteoarthritis

Osteoarthritis (OA) is one of the most common degenerative diseases, and the number of patients has been constantly increasing. Non-steroidal anti-inflammatory drugs, glucocorticosteroids, opioids, etc., and surgical procedures, e.g. arthroplasty, are among the most common methods of treatment. There are reasons to believe that the gut microbiome (GMB) may influence inflammatory processes occurring in the pathomechanism of OA. The inflammatory processes occurring in the intestines may lead to disruption of tight junctions and increased concentrations of pro-inflammatory cytokines, resulting in increased permeability of intestines, causing low-grade inflammation, including in the joints. Methods of altering the GMB composition to reduce the inflammatory and joint degenerative processes are known only to some extent, and long-term research is required. Osteoarthritis, a particularly well-known and very widespread disease due to the aging population, is characterized by moderate and local inflammation. It occurs due to the effects of biomechanical cartilage wear with damage of joint structures, primarily through degenerative processes. OA represents a therapeutic challenge, and any element that can influence its inhibition is highly sought after. Therefore, these methods seem to offer a promising additional approach to treatment.

Gut Microbiota and Osteoarthritis: From Pathogenesis to Novel Therapeutic Opportunities

Osteoarthritis (OA) is the most common chronic degenerative joint disease, characterized by cartilage damage, synovial inflammation, subchondral bone sclerosis, marginal bone loss, and osteophyte development. Clinical manifestations include inflammatory joint pain, swelling, osteophytes, and limitation of motion. The pathogenesis of osteoarthritis has not yet been fully uncovered. With ongoing research, however, it has been gradually determined that OA is not caused solely by mechanical injury or aging, but rather involves chronic low-grade inflammation, metabolic imbalances, dysfunctional adaptive immunity, and alterations in central pain processing centers. The main risk factors for OA include obesity, age, gender, genetics, and sports injuries. In recent years, extensive research on gut microbiota has revealed that gut dysbiosis is associated with some common risk factors for OA, and that it may intervene in its pathogenesis through both direct and indirect mechanisms. Therefore, gut flora imbalance as a pathogenic factor in OA has become a hotspot topic of research, with potential therapeutic connotations. In this paper, we review the role of the gut microbiota in the pathogenesis of OA, describe its relationship with common OA risk factors, and address candidate gut microbiota markers for OA diagnosis. In addition, with focus on OA therapies, we discuss the effects of direct and indirect interventions targeting the gut microbiota, as well as the impact of gut bacteria on the efficacy of OA drugs.

Effects of the Curcuminoid and Non-Curcuminoid Compounds of Turmeric on the Gut Microbiome and Inflammation: Potential Use in the Treatment and Prevention of Disease

The gut microbiome is a complex system that directly interacts with and influences many systems in the body. This delicate balance of microbiota plays an important role in health and disease and is highly influenced by lifestyle factors and the surrounding environment. As further research emerges, understanding the full potential of the gut microbiome and the impact of using nutraceuticals to positively influence its function may open the door to greater therapeutic outcomes in the treatment and prevention of disease. Curcumin, a bioactive compound derived from the turmeric rhizome, has been studied in depth for its influence on human health as a potent anti-inflammatory and antioxidant properties. However, the therapeutic activity of curcumin is limited by its low oral bioavailability. While most available research has primarily focused on the curcuminoid compounds of turmeric, the non-curcuminoid compounds hold promise to offer therapeutic benefits while synergistically enhancing the bioavailability of curcumin and supporting the gut microbiome. This review summarizes current knowledge of the relationship between the gut and the various systems within the body, and how dysbiosis, or disruption in the gut microbial balance, leads to inflammation and increased risk of chronic disease. The review also summarizes recent research that focuses on the bioactivity of both the curcuminoid and non-curcuminoid compounds that comprise the whole turmeric root and their synergistic role in enhancing bioavailability to support a healthy gut microbiome and promising use in the treatment and prevention of disease.

Relationship Between the Gut Microbiome, Tryptophan-Derived Metabolites, and Osteoarthritis-Related Pain: A Systematic Review with Meta-Analysis

INTRODUCTION

Osteoarthritis (OA) is the most prevalent form of arthritis and affects over 528 million people worldwide. Degenerative joint disease involves cartilage degradation, subchondral bone remodeling, and synovial inflammation, leading to chronic pain, stiffness, and impaired joint function. Initially regarded as a "wear and tear" condition associated with aging and mechanical stress, OA is now recognized as a multifaceted disease influenced by systemic factors such as metabolic syndrome, obesity, and chronic low-grade inflammation. Recent studies have focused on the gut-joint axis to investigate how the gut microbiome modulates inflammation and pain in OA.

MATERIALS AND METHODS

A systematic review was conducted following the PRISMA guidelines and was registered with PROSPERO (CRD42024556265). This review included studies involving adults with symptomatic OA and analyzed the relationship between the gut microbiome and OA-related pain. Randomized and non-randomized clinical trials, case reports, editorials, and pilot studies were excluded. Searches were performed in PubMed, Cochrane Library, and Web of Science without publication date restrictions, and filtered for "observational studies". The study selection and data extraction were performed by two independent researchers, and the risk of bias was assessed using appropriate tools.

RESULTS

Five observational studies were included in the systematic review, and three were included in the meta-analysis. Two studies reported an association between different tryptophan metabolites and pain levels in patients with OA. Two other studies demonstrated a correlation between lipopolysaccharide levels and pain in OA. A fifth study confirmed the relationship between Streptococcus relative abundance of Streptococcus spp. and knee pain. These results were not supported by a meta-analysis, which found no significant association between the presence of pain in OA and the presence of bacilli of the genus Streptococcus or plasma markers of the tryptophan pathway.

CONCLUSIONS

Current evidence indicates a potential link between gut microbiome dysbiosis and OA-related pain. However, methodological limitations preclude definitive conclusions. Further research using advanced techniques and larger cohorts is needed to validate and extend these findings and elucidate the underlying mechanisms. Targeted manipulation of the gut microbiome may be a valuable strategy for pain management in OA patients.

Emerging Concepts in Periprosthetic Joint Infection Research: The Human Microbiome

Microorganisms, including bacteria, fungi, and viruses, that reside on and within the human body are collectively known as the human microbiome. Dysbiosis, or disruption in the microbiome, has been implicated in several disease processes, including asthma, obesity, autoimmune diseases, and numerous other conditions. While the Human Microbiome Project and the generation of descriptive studies it inspired established correlations between characteristic patterns in the composition of the microbiome and specific disease phenotypes, current research has begun to focus on elucidating the causal role of the microbiome in disease pathogenesis. Within the field of orthopaedic surgery, researchers have proposed the concept of a "gut-joint axis," whereby the intestinal microbiome influences joint health and the development of diseases, such as osteoarthritis and periprosthetic joint infection (PJI). It is theorized that intestinal dysbiosis increases gut permeability, leading to the translocation of bacteria and their metabolic products into the systemic circulation and the stimulation of proinflammatory response cascades throughout the body, including within the joints. While correlative studies have identified patterns of dysbiotic derangement associated with osteoarthritis and PJI, translational research is needed to clarify the precise mechanisms by which these changes influence disease processes. Additionally, an emerging body of literature has challenged the previously held belief that certain body sites are sterile and do not possess a microbiome, with studies identifying distinct microbial genomic signatures and a core microbiome that varies between anatomic sites. A more thorough characterization of the joint microbiome may have profound implications for our understanding of PJI pathogenesis and our ability to stratify patients based on risk. The purpose of this review was to outline our current understanding of the human microbiome to describe the gut-joint axis and its role in specific pathologies, including PJI, and to highlight the potential of microbiome-based therapeutic interventions in the field of orthopaedics.

Potential role of gut-related factors in the pathology of cartilage in osteoarthritis

Osteoarthritis (OA) is a common progressive degenerative disease. Gut microbiota (GM) and their metabolites have been closely associated with the onset, progression, and pathology of OA. GM and their metabolites may influence the cartilage directly, or indirectly by affecting the gut, the immune system, and the endocrine system. They function through classical pathways in cartilage metabolism and novel pathways that have recently been discovered. Some of them have been used as targets for the prevention and treatment of OA. The current study sought to describe the major pathological signaling pathways in OA chondrocytes and the potential role of gut-related factors in these pathways.

Ketogenic Diet-Associated Worsening of Osteoarthritis Histologic Secerity, Increased Pain Sensitivity and Gut Microbiome Dysbiosis in Mice

OBJECTIVES

Dietary interventions are a potentially powerful treatment option for knee osteoarthritis (OA). The objective of this study was to evaluate a well-formulated ketogenic diet (KD) in the context of knee OA histology and pain using the destabilization of the medial meniscus (DMM) mouse model and correlate with gut microbiome and systemic cytokine levels.

METHODS

Adult male mice underwent unilateral DMM or sham surgery and were then fed eight weeks of KD or chow. At baseline and every two weeks, mechanical allodynia of the operated and contralateral knees was assessed via analgesiometry. Knee joints were collected for histology, gut microbiome analysis was performed on cecal material via 16S sequencing, and serum cytokines were analyzed via Bio-Plex assay.

RESULTS

KD mice had worse histopathologic OA after DMM (mean ± SEM Osteoarthritis Research Society International score: KD-DMM: 4.0 ± 0.5 vs chow-DMM: 2.7 ± 0.08; P = 0.02). KD mice had increased mechanical allodynia postsurgery (P = 0.005 in mixed-effects model). The gut microbiome changed substantially with KD: 59 clades were altered by KD in DMM and 39 by KD in sham (36 were shared, 25 overlapped with previous murine OA studies). Several clades were correlated on an individual-mouse level with both histology and allodynia (eg, Lactobacillus histology P = 0.004, allodynia P = 1 × 10-4). Serum analysis showed four cytokines increased with KD (interleukin [IL]-1β, IL-2, IL-3, and IL-13).

CONCLUSION

KD started immediately after OA induction via DMM is associated with worsened histologic outcomes. KD also worsens mechanical allodynia after either DMM or sham surgery. KD induces significant gut microbiome dysbiosis in clades previously associated with murine OA.

Role of gut microbiota in rheumatoid arthritis: Potential cellular mechanisms regulated by prebiotic, probiotic, and pharmacological interventions

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects joints and multiple organs and systems, which is long-lasting and challenging to cure and significantly impacting patients' quality of life. Alterations in the composition of intestinal flora in both preclinical and confirmed RA patients indicate that intestinal bacteria play a vital role in RA immune function. However, the mechanism by which the intestinal flora is regulated to improve the condition of RA is not fully understood. This paper reviews the methods of regulating gut microbiota and its metabolites through prebiotics, probiotics, and pharmacological interventions, and discusses their effects on RA. Additionally, it explores the potential predictive role of cellular therapy mechanisms of intestinal flora in treating RA. These findings suggest that restoring the ecological balance of intestinal flora and regulating intestinal barrier function may enhance immune system function, thereby improving rheumatoid arthritis. This offers new insights into its treatment.

Correlation of fecal microbiome dysregulation to synovial transcriptome in an equine model of obesity associated osteoarthritis

Background

Osteoarthritis (OA) is increasingly thought to be a multifactorial disease in which sustained gut inflammation serves as a continued source of inflammatory mediators driving degenerative processes at distant sites such as joints. The objective of this study was to use the equine model of naturally occurring obesity associated OA to compare the fecal microbiome in OA and health and correlate those findings to differential gene expression synovial fluid (SF) cells, circulating leukocytes and cytokine levels (plasma, SF) towards improved understanding of the interplay between microbiome and immune transcriptome in OA pathophysiology.

Methods

Feces, peripheral blood mononuclear cells (PBMCs), and SF cells were isolated from healthy skeletally mature horses (n=12; 6 males, 6 females) and those with OA (n=6, 2 females, 4 males). Horses were determined to have OA via lameness evaluation, response to intra-articular (IA) diagnostic analgesia, and radiographic and arthroscopic evidence. Horses were excluded who had received medications or joint injections within 2 months. Cytokine analyses of plasma and SF were performed via multiplex immunoassay. Fecal bacterial microbial 16s DNA sequencing was performed and correlated to bulk RNA sequencing of SF cells and PBMC performed using an Illumina based platform.

Results

Horses with OA had higher body condition scores (P=0.009). Cytokines were elevated in plasma [interleukin (IL)-2, IL-6, IL-18, interferon gamma (IFN-γ), interferon gamma inducible protein 10 (CXCL10 or IP-10), granulocyte colony-stimulating factor (G-CSF)] and SF (IL-1β, IL-6, IL-17A, IL-18, IP-10, G-CSF) in OA. Microbial principal coordinate analysis (PCoA) using Bray-Curtis dissimilarity for β-diversity demonstrated distinct grouping of samples from OA versus healthy horses (P=0.003). Faith alpha diversity was reduced in OA (P=0.02). Analysis of microbiome composition showed differential relative abundance of taxa on multiple levels in OA. Specific phyla (Firmicutes, Verrucomicrobia, Tenericutes, Fibrobacteres), correlated to transcriptomic differences related to cell structure, extracellular matrix, collagen, laminin, migration, and motility, or immune response to inflammation in OA.

Conclusions

These findings provide compelling evidence for a link between obesity, gut microbiome dysbiosis and differential gene expression in distant joint sites associated with development of OA in a relevant large animal model, establishing a connection here that provides a platform from which development of therapeutic interventions targeting the gut microbiome can build.

Insights into Within-Host Evolution and Dynamics of Oral and Intestinal Streptococci Unveil Niche Adaptation

The oral-gut axis is a complex system linking the oral cavity and gastrointestinal tract, impacting host health and microbial composition. This study investigates genetic changes and adaptive mechanisms employed by streptococci-one of the few genera capable of colonizing oral and intestinal niches-within the same individual. We conducted whole-genome sequencing (WGS) on 218 streptococcal isolates from saliva and fecal samples of 14 inflammatory bowel disease (IBD) patients and 12 healthy controls. Our analysis identified 16 streptococcal species, with Streptococcus infantis, S. mitis, S. parasanguinis, S. australis, and S. salivarius being the most prevalent. S. infantis dominated the oral niche in both IBD patients (33%) and healthy controls (26%). It was also the primary species in fecal samples from IBD patients and the second most prevalent in those from healthy controls. S. parasanguinis was more prevalent in the gut than in the oral cavity in both groups. Comparative genomics demonstrated a within-host microevolution of streptococci, showing adaptations via recombination and acquisition of mobile genetic elements (MGEs). Intestinal streptococcal genomes exhibited a higher proportion of intact phages and a significantly greater acquisition of the tetA gene, which confers tetracycline resistance compared to oral genomes. Core-genome single-nucleotide polymorphisms (SNPs) analysis showed significant genetic divergence between oral and intestinal streptococcal genomes within the same individual. Our findings also unveil distinct niche-specific mutation signatures within intestinal genomes, indicating the emergence of distinct clonal lineages within each niche and suggesting that within-host streptococcal evolution is individual-dependent, initiated in the oral cavity.

Exploration of the pathogenesis of nephrotic syndrome and traditional Chinese medicine intervention based on gut microbiota

Nephrotic syndrome (NS) represents a prevalent syndrome among various chronic kidney disease pathologies and is known for its higher severity and worse prognosis compared with chronic glomerulonephritis. Understanding its pathogenesis and identifying more effective treatment modalities have long been a concern of kidney specialists. With the introduction of the gut-kidney axis concept and the progress in omics technologies, alterations in the gut microbiota have been observed in primary and secondary NS. This link has been extensively researched in conditions such as diabetic nephropathy and immunoglobulin A (IgA) nephropathy. Thus, dysbiosis of the gut microbiota is seen as a crucial contributing factor in NS; however, there is a lack of comprehensive reviews that elucidate the changes in the gut microbiota across different NS conditions and that describe its mechanistic role in the disease. Moreover, serving as an innate regulator of the gut microbiota, traditional Chinese medicine (TCM) has the potential to exert a profound impact on the expression of inflammation-promoting agents, decreasing the levels of endotoxins and uremic toxins. In addition, it strengthens the stability of the intestinal barrier while controlling the metabolic function of the body through its efficient modulation of the gut microbiota. This intricate process yields far-reaching consequences for NS.

Sexually dimorphic metabolic effects of a high fat diet on knee osteoarthritis in mice

BACKGROUND

Women have a higher risk of developing osteoarthritis (OA) than men, including with obesity. To better understand this disparity, we investigated sex differences in metabolic and inflammatory factors associated with OA using a diet-induced mouse model of obesity. We hypothesized that 20 weeks of high-fat diet (HFD) would induce sexually dimorphic changes in both systemic and local risk factors of knee OA.

METHODS

Male and female C57BL/6J mice were fed Chow or HFD from 6 to 26 weeks of age (n = 12 per diet and sex). We performed broad metabolic phenotyping, 16 S gut microbiome analysis, targeted gene expression analysis of synovium-infrapatellar fat tissue, targeted gene expression and proteomic analysis of articular cartilage, chondrocyte metabolic profiling, and OA histopathology. Two-way ANOVA statistics were utilized to determine the contribution of sex and diet and their interaction on outcomes.

RESULTS

Mice fed HFD weighed 1.76-fold (p < 0.0001) and 1.60-fold (p < 0.0001) more than male and female Chow cohorts, respectively, with both sexes reaching similar body fat levels (male: 43.9 ± 2.2%; female: 44.1 ± 3.8%). HFD caused greater cartilage pathology (p < 0.024) and synovial hyperplasia (p < 0.038) versus Chow in both sexes. Cartilage pathology was greater in male versus female mice (p = 0.048), and only male mice developed osteophytes with HFD (p = 0.044). Both sexes exhibited metabolic inflexibility on HFD, but only male mice developed glucose intolerance (p < 0.0001), fatty liver (p < 0.0001), and elevated serum amylase (p < 0.0001) with HFD versus Chow. HFD treatment caused sex-dependent differences in gut microbiota beta diversity (p = 0.01) and alteration in specific microbiome clades, such as a HFD-dependent reduction in abundance of Bifidobacterium only in male mice. In knee synovium and infrapatellar fat tissue, HFD upregulated the expression of pro-inflammatory and pro-fibrotic genes predominantly in female mice. In cartilage, lipid metabolism proteins were more abundant with HFD in male mice, whereas proteins involved in glycolysis/gluconeogenesis and biosynthesis of amino acids were greater in cartilage of female mice. Sex-dependent metabolic differences were observed in cartilage from young, healthy mice prior to pubertal maturation, but not in primary juvenile chondrocytes studied in vitro.

CONCLUSIONS

HFD induced numerous sex differences in metabolic and inflammatory outcomes, especially in joint tissues, suggesting that sex-specific cellular processes are involved during development of early-stage OA with obesity.

Evaluation of Four Multispecies Probiotic Cocktails in a Human Colonic Fermentation Model

Bacteriotherapy represents an attractive approach for both prophylaxis and treatment of human diseases. However, combining probiotic bacteria in "cocktails" is underexplored, despite its potential as an alternative multi-target therapy. Herein, three-strain probiotic mixtures containing different combinations of Bacillus (Bc.) coagulans [ATB-BCS-042], Levilactobacillus (Lv.) brevis [THT 0303101], Lacticaseibacillus (Lc.) paracasei [THT 031901], Bacillus subtilis subsp. natto [ATB-BSN-049], Enterococcus faecium [ATB-EFM-030], and Bifidobacterium (Bf.) animalis subsp. lactis [THT 010802] were prepared. Four cocktails (PA: Bc. coagulans + Lv. brevis + Lc. paracasei, PB: Bc. subtilis subsp. natto + Lv. brevis + Lc. paracasei, PC: E. faecium + Lv. brevis + Lc. paracasei, PD: Bc. coagulans + Lv. brevis + Bf. animalis subsp. lactis) were tested using a short-term (72 h) simulation of the human colonic microbiota in a final dose of 6 × 109 CFU. All these probiotic mixtures significantly increased butyrate production compared to the parallel control experiment. PA and PB promoted a bifidogenic effect and facilitated lactobacilli colonization. Furthermore, reporter gene assays using the AhR_HT29-Lucia cell line revealed that fermentation supernatants from PA and PB notably induced AhR transactivity. Subsequent examination of the metabolic outputs of PA and PB in intestinal epithelial models using cell culture inserts suggested no significant impact on the transepithelial electrical resistance (TEER). Assessment of the expression of proinflammatory and anti-inflammatory cytokines, as well as AhR-related target genes in the Caco-2 cell monolayers indicated that PB's metabolic output upregulated most of the measured endpoints. This in vitro investigation evaluated the potential impact of four multispecies probiotic mixtures in the human colonic microbiota and identified a promising formulation comprising a combination of Bc. subtilis subsp. natto, Lv. brevis, and Lc. paracasei as a promising formulation for further study.

Gut Microbiome and Osteoarthritis: Insights From the Naturally Occurring Canine Model of Osteoarthritis

OBJECTIVE

The purpose of this study was to enhance the current knowledge of the relationship between the gut microbiome and osteoarthritis (OA) and associated pain using pet dogs as a clinically relevant translational model.

METHODS

Fecal samples were collected from 93 owned pet dogs. Dogs were designated as either clinically healthy or OA pain using validated methods. Metagenomic profiling was performed through shotgun sequencing using the Illumina NovaSeq platform. MetaPhlAn2 and HUMAnN2 were used to evaluate bacterial taxonomic and pathway relative abundance. Comparisons between healthy and OA-pain groups were performed individually for each taxa using nonparametric tests following Benjamini and Hochberg adjustment for multiple comparisons. Permutation analysis of variance was performed using Bray-Curtis distance matrices. All downstream analyses were completed in R.

RESULTS

No significant differences between healthy and OA-pain dogs were observed for alpha and beta diversity. We found 13 taxa with nominally significant (P < 0.05) associations with OA case status, but none of the associations remained significant after adjustment for multiple comparisons. No differences in alpha or beta diversities or the Firmicutes to Bacteroidetes ratio were found regarding pain severity, mobility or activity level, age, or body composition score.

CONCLUSION

Similar to recent studies in humans, the present study did not demonstrate a significant difference in the fecal microbial communities between dogs with OA pain and healthy control dogs. Future research in this naturally occurring model should expand on these data and relate the gut microbiome to gut permeability and circulating proinflammatory and anti-inflammatory molecules to better understand the influence of the gut microbiome on OA and OA pain.

Association between thyroid function and osteoarthritis: A population-based cohort study

OBJECTIVES

Previous genetic and animal studies indicated a causal role of thyroid hormones in osteoarthritis (OA), which has not been observed in the general population. We aimed to investigate whether thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were associated with hand, hip, or knee OA.

METHODS

Participants from the Rotterdam Study with baseline TSH, FT4, and joint radiographs were included. We used multivariable regression models to investigate the association of thyroid function with the prevalence, severity, incidence, and progression of OA. We conducted stratified analyses by sex, age, body mass index (BMI) and weight-bearing physical activity.

RESULTS

Among 9054 participants included (mean age 65 years, 56.3% women), higher FT4 concentrations were associated with an increased risk of prevalent knee OA (odd ratio [OR] 1.04 per pmol/L, 95% CI 1.01-1.06, corresponding to an OR of 1.62 across the reference range [i.e., 14pmol/L changes] of FT4) and more severe knee OA. There was a positive association between FT4 and overall progression of knee OA (OR 1.03 per pmol/L, 1.00-1.07). No association of TSH with hand, hip, or knee OA was identified. Stratified analysis revealed an association between FT4 and prevalent knee OA among individuals with BMI ≥30 kg/m2 (OR 1.05 per pmol/L, 1.01-1.08) and those with high levels of weight-bearing physical activity (OR 1.05 per pmol/L, 1.01-1.10).

CONCLUSIONS

Our study indicated that higher FT4 concentrations may increase the risk of knee OA. This association might be greater in individuals with extra joint loading, such as those with obesity.

Exploring the mechanism of action of Modified Simiao Powder in the treatment of osteoarthritis: an in-silico study

Introduction

Osteoarthritis (OA) is the most common form of arthritis and the leading musculoskeletal disorders in adults. Modified Simiao Powder (MSMP) has been widely used in the treatment of OA with remarkable clinical ecaciousness.

Objective

This study aimed to elucidate underlying mechanisms of MSMP in OA by employing network pharmacology, molecular docking, and molecular dynamics simulations, due to the unclear mode of action.

Methods

Bioinformatic analysis was used to evaluate the major chemical constituents of MSMP, determine prospective target genes, and screen genes associated with OA. Network pharmacology methods were then applied to identify the crucial target genes of MSMP in OA treatment. Further analyses included gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. These key targets within the pertinent pathways was further confirmed by molecular docking, binding energy evaluation, and molecular dynamics simulations.

Results

Network pharmacology analysis identified an MSMP component-target-pathway network comprising 11 central active compounds, 25 gene targets, and 12 biological pathways.

Discussion

These findings imply that the therapeutic effects of MSMP was potentially mediated by targeting several pivotal genes, such as androgen receptor (AR), NFKB1, AKT1, MAPK1, and CASP3, and regulating some pathways, including lipid metabolism and atherosclerosis, the AGE-RAGE signaling pathway in diabetic complications, the PI3K-Akt signaling pathway, fluid shear stress, atherosclerosis, and Kaposi's sarcoma-associated herpesvirus infection. Molecular docking assessments demonstrated that these compounds of MSMP, such as berberine, kaempferol, quercetin, and luteolin, exhibit high binding anities to AR and AKT1. Molecular dynamics simulations validated the interactions between these compounds and targets.

Conclusion

The therapeutic effect of MSMP likely attributed to the modulation of multiple pathways, including lipid metabolism, atherosclerosis, the AGE-RAGE signaling pathway, and the PI3K-Akt signaling pathway, by the active components such as berberine, kaempferol, luteolin, and quercetin. Especially, their actions on target genes like AR and AKT1 contribute to the therapeutic benefits of MSMP observed in the treatment of OA.

The Potential Role of Boron in the Modulation of Gut Microbiota Composition: An In Vivo Pilot Study

Background/Objectives: The role of the gut microbiome in the development and progression of many diseases has received increased attention in recent years. Boron, a trace mineral found in dietary sources, has attracted interest due to its unique electron depletion and coordination characteristics in chemistry, as well as its potential role in modulating the gut microbiota. This study investigates the effects of inorganic boron derivatives on the gut microbiota of mice. Methods: For three weeks, boric acid (BA), sodium pentaborate pentahydrate (NaB), and sodium perborate tetrahydrate (SPT) were dissolved (200 mg/kg each) in drinking water and administered to wild-type BALB/c mice. The composition of the gut microbiota was analyzed to determine the impact of these treatments. Results: The administration of BA significantly altered the composition of the gut microbiota, resulting in a rise in advantageous species such as Barnesiella and Alistipes. Additionally, there was a decrease in some taxa associated with inflammation and illness, such as Clostridium XIVb and Bilophila. Notable increases in genera like Treponema and Catellicoccus were observed, suggesting the potential of boron compounds to enrich microbial communities with unique metabolic functions. Conclusions: These findings indicate that boron compounds may have the potential to influence gut microbiota composition positively, offering potential prebiotic effects. Further research with additional analyses is necessary to fully understand the interaction between boron and microbiota and to explore the possibility of their use as prebiotic agents in clinical settings.

A Sustained-Release Butyrate Tablet Suppresses Ex Vivo T Helper Cell Activation of Osteoarthritis Patients in a Double-Blind Placebo-Controlled Randomized Trial

Degenerative joint disease osteoarthritis (OA) is characterized by the degeneration of cartilage, synovial inflammation and low-grade systemic inflammation in association with microbial dysbiosis and intestinal barrier defects. Butyrate is known for its anti-inflammatory and barrier protective effects and might benefit OA patients. In a double-blind placebo-controlled randomized trial, the effects of four to five weeks of oral treatment with sustained-release (SR) butyrate tablets (600 mg/day) on systemic inflammation and immune function were studied in hand OA patients. Serum markers for systemic inflammation and lipopolysaccharide (LPS) leakage were measured and ex vivo stimulation of whole blood or peripheral blood mononuclear cells (PBMCs) was performed at baseline and after treatment. Butyrate treatment did not affect the serum markers nor the cytokine release of ex vivo LPS-stimulated whole blood or PBMCs nor the phenotype of restimulated monocytes. By contrast, butyrate treatment reduced the percentage of activated T helper (Th) cells and the Th17/Treg ratio in αCD3/CD28-activated PBMCs, though cytokine release upon stimulation remained unaffected. Nevertheless, the percentage of CD4+IL9+ cells was reduced by butyrate as compared to the placebo. In both groups, the frequency of Th1, Treg, Th17, activated Th17, CD4+IFNγ+ and CD4+TNFα+ cells was reduced. This study shows a proof of principle of some immunomodulatory effects using a SR butyrate treatment in hand OA patients. The inflammatory phenotype of Th cells was reduced, as indicated by a reduced percentage of Th9 cells, activated Th cells and improved Th17/Treg balance in ex vivo αCD3/CD28-activated PBMCs. Future studies are warranted to further optimize the butyrate dose regime to ameliorate inflammation in OA patients.

Exploring the Interconnection between Metabolic Dysfunction and Gut Microbiome Dysbiosis in Osteoarthritis: A Narrative Review

Osteoarthritis (OA) is a prevalent joint disorder and the most common form of arthritis, affecting approximately 500 million people worldwide, or about 7% of the global population. Its pathogenesis involves a complex interplay between metabolic dysfunction and gut microbiome (GM) alterations. This review explores the relationship between metabolic disorders-such as obesity, diabetes, and dyslipidemia-and OA, highlighting their shared risk factors, including aging, sedentary lifestyle, and dietary habits. We further explore the role of GM dysbiosis in OA, elucidating how systemic inflammation, oxidative stress, and immune dysregulation driven by metabolic dysfunction and altered microbial metabolites contribute to OA progression. Additionally, the concept of "leaky gut syndrome" is discussed, illustrating how compromised gut barrier function exacerbates systemic and local joint inflammation. Therapeutic strategies targeting metabolic dysfunction and GM composition, including lifestyle interventions, pharmacological and non-pharmacological factors, and microbiota-targeted therapies, are reviewed for their potential to mitigate OA progression. Future research directions emphasize the importance of identifying novel biomarkers for OA risk and treatment response, adopting personalized treatment approaches, and integrating multiomics data to enhance our understanding of the metabolic-GM-OA connection and advance precision medicine in OA management.

Microbiome and Femoral Cartilage Thickness in Knee Osteoarthritis: Is There a Link?

OBJECTIVE

To assess the relation between microbiome and lipopolysaccharide (LPS), in the blood and synovial fluid (SF) with femoral cartilage thickness (FCT) measured by ultrasound (US) in knee osteoarthritis (KOA) patients.

METHODS

This cross-sectional study included 40 primary KOA patients recruited between September 2022 and June 2023. Age, gender, and body mass index (BMI) were recorded. Patients underwent full clinical examination, standing plain x-ray of the knee joint and knee US examination to measure medial, intercondylar, and lateral FCT. Microbiomes (specific bacterial phyla) were detected by real-time polymerase chain reaction and LPS levels were measured by enzyme-linked immunosorbent assay kit in the patients' serum and SF.

RESULTS

The patient's age ranged from 43 to 72 years. Most patients were females (72.5%), with a mean BMI of 35.8 ± 6.21 kg/m2. The mean medial, intercondylar, and lateral FCT were less than cut-off values. All 40 (100%) patients showed positive bacterial deoxyribonucleic acid (16S ribosomal RNA) in both blood and SF samples. Firmicutes was the most abundant in patients' blood (48.49%) and SF (63.59%). The mean serum LPS level was significantly higher compared to mean SF LPS (t =4.702, P < 0.001). There was a statistically significant negative correlation between lateral FCT and Firmicutes relative abundance in both patients' blood and SF.

CONCLUSION

Microbiome and LPS are present in the blood and SF of primary KOA patients. Microbiome (Firmicutes) was associated with decreased lateral FCT. This might provide a potential link between both systemic and local microbiomes and cartilage affection in KOA patients.

The role of obesity and adipose tissue dysfunction in osteoarthritis pain

Obesity has a pivotal and multifaceted role in pain associated with osteoarthritis (OA), extending beyond the mechanistic influence of BMI. It exerts its effects both directly and indirectly through various modifiable risk factors associated with OA-related pain. Adipose tissue dysfunction is highly involved in OA-related pain through local and systemic inflammation, immune dysfunction, and the production of pro-inflammatory cytokines and adipokines. Adipose tissue dysfunction is intricately connected with metabolic syndrome, which independently exerts specific effects on OA-related pain, distinct from its association with BMI. The interplay among obesity, adipose tissue dysfunction and metabolic syndrome influences OA-related pain through diverse pain mechanisms, including nociceptive pain, peripheral sensitization and central sensitization. These complex interactions contribute to the heightened pain experience observed in individuals with OA and obesity. In addition, pain management strategies are less efficient in individuals with obesity. Importantly, therapeutic interventions targeting obesity and metabolic syndrome hold promise in managing OA-related pain. A deeper understanding of the intricate relationship between obesity, metabolic syndrome and OA-related pain is crucial and could have important implications for improving pain management and developing innovative therapeutic options in OA.

The Oral Administration of Lactobacillus delbrueckii subsp. lactis 557 (LDL557) Ameliorates the Progression of Monosodium Iodoacetate-Induced Osteoarthritis

Low-grade body inflammation is a major cause of osteoarthritis (OA), a common joint disease. Gut dysbiosis may lead to systemic inflammation which can be prevented by probiotic administration. The Lactobacillus delbrueckii subsp. lactis 557 (LDL557) has been demonstrated to have beneficial effects for anti-inflammation. This study investigated the effects of LDL557 on OA progress using monosodium iodoacetate (MIA)-induced OA of rats. Live or heat-killed (HK)-LDL557 of a low or high dose was administrated for two weeks before MIA-induced OA, and then continuously administrated for another six weeks. After taking supplements for eight weeks, OA progress was analyzed. Results showed that MIA induced knee joint swelling, chondrocyte damage, and cartilage degradation, and supplementation with a high dose of LDL557 reduced MIA-induced knee joint swelling, chondrocyte damage, and cartilage degradation. Additionally, MIA increased serum levels of the matrix-degrading enzyme MMP-13, while a high dose of HK-LDL557 decreased it for the controls. Simultaneously, bone turnover markers and inflammatory cytokines of serum were assayed, but no significant differences were found except for a TNF-α decrease from a low dose of live LDL557. These results demonstrated that supplementation with high doses of live LDL557 or HK-LDL557 can reduce the progression of MIA-induced OA in rats.

Glycerol monolaurate regulates apoptosis and inflammation by suppressing lipopolysaccharide-induced ROS production and NF-κB activation in avian macrophages

Macrophages play a crucial role in both innate and adaptive immunity. However, their abnormal activation can lead to undesirable inflammatory reactions. This study aimed to investigate the effects of glycerol monolaurate (GML), a natural monoester known for its anti-inflammatory and immunoregulatory properties, on avian macrophages using the HD11 cell line. The results indicated that a concentration of 10 μg/mL of GML enhanced the phagocytic activity of HD11 cells (P < 0.05) without affecting cell viability (P > 0.05). GML decreased the expression of M1 macrophage polarization markers, such as CD86 and TNF-α genes (P < 0.05), while increasing the expression of M2 macrophage polarization markers, such as TGF-β1 and IL-10 genes (P < 0.05). GML suppressed ROS production, apoptosis, and the expression of proinflammatory genes (IL-1β and IL-6) induced by LPS (P < 0.05). GML also promoted the expression of TGF-β1 and IL-10 (P < 0.05), both in the presence and absence of LPS exposure. Moreover, GML suppressed the gene expression of TLR4 and NF-κB p65 induced by LPS (P < 0.05), as well as the phosphorylation of NF-κB p65 (P < 0.05). In conclusion, GML exhibited regulatory effects on the polarized state of avian macrophages and demonstrated significant anti-apoptotic and anti-inflammatory properties by suppressing intracellular ROS and the NF-κB signaling pathway.

A further examination of growth factors, T helper 1 polarization, and the gut microbiome in major depression: Associations with reoccurrence of illness, cognitive functions, suicidal behaviors, and quality of life

Growth factors, T helper (Th)1 polarization, and the microbiome are involved in the pathophysiology of major depression (MDD). It remains unclear whether the combination of these three pathways could enhance the accuracy of predicting the features of MDD, including recurrence of illness (ROI), suicidal behaviors and the phenome. We measured serum stem cell factor (SCF), stem cell growth factor (SCGF), stromal cell-derived factor-1 (SDF-1), platelet-derived growth factor (PDGF), hepatocyte growth factor (HGF), macrophage-colony stimulating factor (M-CSF) and vascular endothelial growth factor (VEGF), the ratio of serum Th1/Th2 cytokines (zTh1-zTh2), and the abundances of gut microbiome taxa by analyzing stool samples using 16S rDNA sequencing from 32 MDD patients and 37 healthy controls. The results show that serum SCF is significantly lower and VEGF increased in MDD. Adverse childhood experiences (ACE) and ROI are significantly associated with lowered SCF and increasing VEGF. Lifetime and current suicidal behaviors are strongly predicted (63.5%) by an increased VEGF/SCF ratio, Th1 polarization, a gut microbiome enterotype indicating gut dysbiosis, and lowered abundance of Dorea and Faecalobacterium. Around 80.5% of the variance in the phenome's severity is explained by ROI, ACEs, and lowered Parabacteroides distasonis and Clostridium IV abundances. A large part of the variance in health-related quality of life (54.1%) is explained by the VEGF/SCF ratio, Th1 polarization, ACE, and male sex. In conclusion, key features of MDD are largely predicted by the cumulative effects of ACE, Th1 polarization, aberrations in growth factors and the gut microbiome with increased pathobionts but lowered beneficial symbionts.

The Role and Applications of Artificial Intelligence in the Treatment of Chronic Pain

PURPOSE OF REVIEW

This review aims to explore the interface between artificial intelligence (AI) and chronic pain, seeking to identify areas of focus for enhancing current treatments and yielding novel therapies.

RECENT FINDINGS

In the United States, the prevalence of chronic pain is estimated to be upwards of 40%. Its impact extends to increased healthcare costs, reduced economic productivity, and strain on healthcare resources. Addressing this condition is particularly challenging due to its complexity and the significant variability in how patients respond to treatment. Current options often struggle to provide long-term relief, with their benefits rarely outweighing the risks, such as dependency or other side effects. Currently, AI has impacted four key areas of chronic pain treatment and research: (1) predicting outcomes based on clinical information; (2) extracting features from text, specifically clinical notes; (3) modeling 'omic data to identify meaningful patient subgroups with potential for personalized treatments and improved understanding of disease processes; and (4) disentangling complex neuronal signals responsible for pain, which current therapies attempt to modulate. As AI advances, leveraging state-of-the-art architectures will be essential for improving chronic pain treatment. Current efforts aim to extract meaningful representations from complex data, paving the way for personalized medicine. The identification of unique patient subgroups should reveal targets for tailored chronic pain treatments. Moreover, enhancing current treatment approaches is achievable by gaining a more profound understanding of patient physiology and responses. This can be realized by leveraging AI on the increasing volume of data linked to chronic pain.

The Effect of Probiotics on the Management of Pain and Inflammation in Osteoarthritis: A Systematic Review and Meta-Analysis of Clinical Studies

Osteoarthritis (OA) is one of the most common musculoskeletal disorders. Recently, research has focused on the role of intestinal microbiome dysbiosis in OA. The aim of this study was to systematically review randomized intervention clinical studies investigating the effect of probiotics on the management of OA-related pain and inflammation. Pre-clinical studies and non-randomized trials were excluded. A literature search was conducted using MEDLINE, EMBASE, and Web of Science. Study quality was assessed with the Cochrane risk of bias (RoB2) tool and the Risk of Bias in N-of-1 Trials (RoBiNT) scale. RevMan was used for the meta-analysis. Outcome measures assessed self-reported pain, stiffness and impediment, and serum hs-CRP. Three studies, with 501 participants, were considered eligible for qualitative synthesis and meta-analysis. A significant reduction in symptoms across all outcomes measured, except stiffness, was evident with Lactobacillus casei Shirota. However, all other probiotics reviewed did not seem to have any effect on the measured outcomes. Pre-clinical evidence, along with the RCTs reviewed, suggests that probiotics of the Lactobacillus strains might be of use for managing pain and inflammation in OA. Considering the small number of studies included in the present review and the possible risk of bias, we conclude that further studies on the role of probiotics in humans with OA are warranted.

Gut microbiota promotes pain chronicity in Myosin1A deficient male mice

Chronic pain is a heavily debilitating condition and a huge socio-economic burden, with no efficient treatment. Over the past decade, the gut microbiota has emerged as an important regulator of nervous system's health and disease states. Yet, its contribution to the pathogenesis of chronic somatic pain remains poorly documented. Here, we report that male but not female mice lacking Myosin1a (KO) raised under single genotype housing conditions (KO-SGH) are predisposed to develop chronic pain in response to a peripheral tissue injury. We further underscore the potential of MYO1A loss-of-function to alter the composition of the gut microbiota and uncover a functional connection between the vulnerability to chronic pain and the dysbiotic gut microbiota of KO-SGH males. As such, parental antibiotic treatment modifies gut microbiota composition and completely rescues the injury-induced pain chronicity in male KO-SGH offspring. Furthermore, in KO-SGH males, this dysbiosis is accompanied by a transcriptomic activation signature in the dorsal root ganglia (DRG) macrophage compartment, in response to tissue injury. We identify CD206+CD163- and CD206+CD163+ as the main subsets of DRG resident macrophages and show that both are long-lived and self-maintained and exhibit the capacity to monitor the vasculature. Consistently, in vivo depletion of DRG macrophages rescues KO-SGH males from injury-induced chronic pain underscoring a deleterious role for DRG macrophages in a Myo1a-loss-of function context. Together, our findings reveal gene-sex-microbiota interactions in determining the predisposition to injury-induced chronic pain and point-out DRG macrophages as potential effector cells.

Hand osteoarthritis: A fresh look

Hand osteoarthritis (OA) has been the subject of numerous publications in recent years, particularly in the fields of imaging and therapeutics. The imaging studies revealed a good correlation between the presence of synovitis and/or subchondral edema and arthritic joint pain. Several randomized controlled trials (RCTs) have assessed the efficacy of biologics and conventional DMARDs in patients with symptomatic hand OA. No less than six RCTs have evaluated the symptomatic and, in some cases, structural efficacy of anti-IL-1, anti-TNF or anti-IL-6 drugs. Overall, the results of these trials were disappointing - none of them demonstrated superiority over placebo. There were also two negative trials with hydroxychloroquine. In the end, the only trial that was positive evaluated 10mg oral prednisone versus placebo for 6 weeks in patients with flares of hand OA and synovitis visible on ultrasound. While that trial confirms the role of inflammation in hand OA, it should obviously not encourage the long-term use of corticosteroids as a symptomatic treatment.

Chronic pain and complex regional pain syndrome are associated with alterations to the intestinal microbiota in both humans and mice. An observational cross-sectional study

Objective

This study aimed to evaluate pain metrics and gut microbiota differences from human subjects with complex regional pain syndrome (CRPS) compared to cohabitants (HHC) and non-cohabitating (biobank) controls. In addition, we aimed evaluate longitudinal changes of gut microbiota using a mouse model of acute and chronic CRPS.

Methods

In an observational, cross-sectional study, 25 patients with CRPS and 24 household controls (HHC) were recruited, completed pain questionnaires, and submitted stool samples. 23 biobank stool samples were matched to the CRPS group. Additionally, longitudinal stool samples were collected from a mouse model of acute and chronic CRPS. 16S rRNA gene sequencing analysis was performed on all samples.

Results

A diagnosis of CRPS is associated with higher pain, increased pain interference, and decreased physical and social function when compared to HHC. Interestingly, 46% of HHC reported significant daily pain. In the households where HHC were also suffering from pain, there was decreased bacterial richness and diversity when compared to households wherein only the participant with CRPS suffered from pain. Furthermore, when comparing households where the HHC had significant pain, CRPS was clinically more severe. In the mouse model of CRPS, we observed decreased bacterial richness and diversity when compared to non-cohabitating littermate controls.

Conclusions

Both humans living in chronic pain households and mice shared distinct taxa over the time course of disease and pain chronicity. These findings suggest that microbiota changes seen in CRPS as well as in a mouse model of CRPS may reflect pain chronicity and may indicate that pain alone can contribute to microbiota dysbiosis. The trial was registered at ClinicalTrials.gov (NCT03612193).

Role of Nutrition in the Management of Patients with Chronic Musculoskeletal Pain

Chronic musculoskeletal pain (CMP), defined as persistent discomfort in musculoskeletal tissues persisting for over 3 months, afflicts an estimated 1.71 billion people globally, leading to significant functional impairments and psychological distress, thereby detrimentally affecting individuals' quality of life. The objective of this narrative review is to elucidate the complex relationship among dietary habits, sarcopenia, and gut microbiota composition, with an eye toward enhancing patient management and outcomes. Given the burgeoning interest in the influence of diet on CMP, a detailed examination of the current literature is warranted. Nutritional intake is a critical determinant of the gut microbiota profile, which, in turn, is linked to musculature integrity and performance, potentially leading to sarcopenia. The development of sarcopenia can aggravate CMP owing to diminished muscular strength and functionality. Additionally, disruptions in the gut microbiota may directly modulate nociception, intensifying CMP manifestations. Thus, nutritional optimization emerges as a viable approach to CMP management. Emphasizing a diet conducive to a healthy gut microbiome could forestall or mitigate sarcopenia, thereby attenuating CMP intensity. Nevertheless, the domain calls for further empirical exploration to unravel the nuances of these interactions and to forge efficacious dietary strategies for individuals with CMP. Beyond mere analgesia, comprehensive patient care for CMP requires acknowledgment of the complex and multifactorial nature of pain and its foundational elements. Embracing an integrative treatment model allows healthcare practitioners to promise better patient prognoses, enriched life quality, and a decrease in the sustained healthcare costs associated with CMP.

Proton pump inhibitors alter gut microbiota by promoting oral microbiota translocation: a prospective interventional study

BACKGROUND

The mechanism by which proton pump inhibitors (PPIs) alter gut microbiota remains to be elucidated. We aimed to learn whether PPI induced gut microbiota alterations by promoting oral microbial translocation.

METHODS

Healthy adult volunteers were randomly assigned: PP group (n=8, 40 mg esomeprazole daily for seven days) and PM group (n=8, 40 mg esomeprazole along with chlorhexidine mouthwash after each meal for seven days). Fecal and saliva samples were analysed using 16S ribosomal RNA sequencing. Mouse models were introduced to confirm the findings in vivo, while the effect of pH on oral bacteria proliferation activity was investigated in vitro.

RESULTS

Taxon-based analysis indicated that PPI administration increased Streptococcus abundance in gut microbiota (P<0.001), and the increased species of Streptococcus were found to be from the oral site or oral/nasal sites, in which Streptococcus anginosus was identified as the significantly changed species (P<0.004). Microbial source tracker revealed that PPI significantly increased the contribution of oral bacteria to gut microbiota (P=0.026), and no significant difference was found in PM group (P=0.467). Compared to the baseline, there was a 42-fold increase in gut abundance of Streptococcus anginosus in PP group (P=0.002), and the times decreased to 16-fold in PM group (P=0.029). Mouse models showed that combination of PPI and Streptococcus anginosus significantly increased the gut abundance of Streptococcus anginosus compared with using PPI or Streptococcus anginosus only. Furthermore, Streptococcus anginosus cannot survive in vitro at a pH lower than 5.

CONCLUSIONS

PPIs altered gut microbiota by promoting oral-originated Streptococcus translocation into gut.

Microbial Symphony: Exploring the Role of the Gut in Osteoarthritis-Related Pain. A Narrative Review

One of the most common musculoskeletal disorders, osteoarthritis (OA), causes worldwide disability, morbidity, and poor quality of life by degenerating articular cartilage, modifying subchondral bone, and inflaming synovial membranes. OA pathogenesis pathways must be understood to generate new preventative and disease-modifying therapies. In recent years, it has been acknowledged that gut microbiota (GM) can significantly contribute to the development of OA. Dysbiosis of GM can disrupt the "symphony" between the host and the GM, leading to a host immunological response that activates the "gut-joint" axis, ultimately worsening OA. This narrative review summarizes research supporting the "gut-joint axis" hypothesis, focusing on the interactions between GM and the immune system in its two main components, innate and adaptive immunity. Furthermore, the pathophysiological sequence of events that link GM imbalance to OA and OA-related pain is broken down and further investigated. We also suggest that diet and prebiotics, probiotics, nutraceuticals, exercise, and fecal microbiota transplantation could improve OA management and represent a new potential therapeutic tool in the light of the scarce panorama of disease-modifying osteoarthritis drugs (DMOADs). Future research is needed to elucidate these complex interactions, prioritizing how a particular change in GM, i.e., a rise or a drop of a specific bacterial strain, correlates with a certain OA subset to pinpoint the associated signaling pathway that leads to OA.

Anti-Inflammatory Effects of Boric Acid in Treating Knee Osteoarthritis: Biochemical and Histopathological Evaluation in Rat Model

This study aimed to examine the anti-inflammatory properties of boric acid (BA) in treating knee osteoarthritis (KOA) in rats, evaluating its biochemical and histopathological therapeutic effects. A KOA rat model was induced by injecting monosodium iodoacetate into the knee joint. Random assignment was performed for the experimental groups as follows: group-1(control), group-2(KOA control), group-3 (BA:4 mg/kg, orally), group-4(BA:10 mg/kg, orally), group-5(BA:4 mg/kg, intra-articularly), and group-6(BA:10 mg/kg, intra-articularly). The rats received 100 µL of BA intra-articularly on days 1, 7, 14, and 21 or 1 mL orally once a day (5 days/week) for 4 weeks. Serum levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and activity of matrix metalloproteinase-13 (MMP-13) were measured. Histopathological and immunohistochemical analyses were performed on knee joint samples using specific antibodies for IL-1β, TNF-α, MMP-13, and nitric oxide synthase-2 (NOS-2). Group-2 exhibited higher serum IL-1β and TNF-α levels and MMP-13 activity than group-1 (P < 0.05). However, IL-1β and TNF-α levels and MMP-13 activity were lower in all treatment groups than in group-2, with statistically significant reductions observed in groups-4, 5, and 6. Histopathologically, group-2 displayed joint space narrowing, cartilage degeneration, and deep fissures. Groups-5 and 6 demonstrated significant joint space enlargement, articular cartilage tissue regeneration, and immunostaining patterns similar to those in group-1. Immunohistochemically, group-2 showed significant increases in IL-1β, TNF-α, MMP-13, and NOS-2 expression. However, all treatment groups exhibited reductions in these expression levels compared to group-2, with statistically significant decreases observed in groups-5 and 6 (P < 0.01). BA shows potential efficacy in reducing inflammation in experimental KOA model in rats. It may be a promising therapeutic agent for KOA, warranting further clinical studies for validation.

Leucine improves thiram-induced tibial dyschondroplasia and gut microbiota dysbiosis in broilers

Thiram, a commonly used agricultural insecticide and fungicide, has been found to cause tibial dyschondroplasia (TD) in broilers, leading to substantial economic losses in the poultry industry. In this study, we aimed to investigate the mechanism of action of leucine in mitigating thiram-induced TD and leucine effects on gut microbial diversity. Broiler chickens were randomly divided into five equal groups: control group (standard diet), thiram-induced group (thiram 80 mg/kg from day 3 to day 7), and different concentrations of leucine groups (0.3%, 0.6%, 0.9% leucine from day 8 to day 18). Performance indicator analysis and tibial parameter analysis showed that leucine positively affected thiram-induced TD broilers. Additionally, mRNA expressions and protein levels of HIF-1α/VEGFA and Ihh/PTHrP genes were determined via quantitative real-time polymerase chain reaction and western blot. The results showed that leucine recovered lameness disorder by downregulating the expression of HIF-1α, VEGFA, and PTHrP while upregulating the expression of Ihh. Moreover, the 16 S rRNA sequencing revealed that the leucine group demonstrated a decrease in the abundance of harmful bacteria compared to the TD group, with an enrichment of beneficial bacteria responsible for producing short-chain fatty acids, including Alistipes, Paludicola, CHKCI002, Lactobacillus, and Erysipelatoclostridium. In summary, the current study suggests that leucine could improve the symptoms of thiram-induced TD and maintain gut microbiota homeostasis.

Gold nanoparticles exhibit anti-osteoarthritic effects via modulating interaction of the "microbiota-gut-joint" axis

Osteoarthritis (OA) is a common degenerative joint disease that can cause severe pain, motor dysfunction, and even disability. A growing body of research indicates that gut microbiota and their associated metabolites are key players in maintaining bone health and in the progression of OA. Short-chain fatty acids (SCFAs) are a series of active metabolites that widely participate in bone homeostasis. Gold nanoparticles (GNPs) with outstanding anti-bacterial and anti-inflammatory properties, have been demonstrated to ameliorate excessive bone loss during the progression of osteoporosis (OP) and rheumatoid arthritis (RA). However, the protective effects of GNPs on OA progression are not clear. Here, we observed that GNPs significantly alleviated anterior cruciate ligament transection (ACLT)-induced OA in a gut microbiota-dependent manner. 16S rDNA gene sequencing showed that GNPs changed gut microbial diversity and structure, which manifested as an increase in the abundance of Akkermansia and Lactobacillus. Additionally, GNPs increased levels of SCFAs (such as butyric acid), which could have improved bone destruction by reducing the inflammatory response. Notably, GNPs modulated the dynamic balance of M1/M2 macrophages, and increased the serum levels of anti-inflammatory cytokines such as IL-10. To sum up, our study indicated that GNPs exhibited anti-osteoarthritis effects via modulating the interaction of "microbiota-gut-joint" axis, which might provide promising therapeutic strategies for OA.

The Microbial Revolution in the World of Joint Replacement Surgery

Background

The prevalence of revision surgery due to aseptic loosening and periprosthetic joint infection (PJI) following total hip and knee arthroplasty is growing. Strategies to prevent the need for revision surgery and its associated health-care costs and patient morbidity are needed. Therapies that modulate the gut microbiota to influence bone health and systemic inflammation are a novel area of research.

Methods

A literature review of preclinical and clinical peer-reviewed articles relating to the role of the gut microbiota in bone health and PJI was performed.

Results

There is evidence that the gut microbiota plays a role in maintaining bone mineral density, which can contribute to osseointegration, osteolysis, aseptic loosening, and periprosthetic fractures. Similarly, the gut microbiota influences gut permeability and the potential for bacterial translocation to the bloodstream, increasing susceptibility to PJI.

Conclusions

Emerging evidence supports the role of the gut microbiota in the development of complications such as aseptic loosening and PJI after total hip or knee arthroplasty. There is a potential for microbial therapies such as probiotics or fecal microbial transplantation to moderate the risk of developing these complications. However, further investigation is required.

Clinical Relevance

Modulation of the gut microbiota may influence patient outcomes following total joint arthroplasty.