Targeting the gut microbiome to treat the osteoarthritis of obesity

The effect of Miya on skeletal muscle changes by regulating gut microbiota in rats with osteoarthritis through AMPK pathway

BACKGROUND

The study aimed to explore whether Miya (MY), a kind of Clostridium butyricum, regulated osteoarthritis (OA) progression through adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway.

METHODS

The OA rats were orally given MY daily for 4 weeks and were intramuscularly injected with AMPK inhibitor once a week for 4 weeks. Hematoxylin eosin (HE) staining was used to observe the histological morphology of the knee joint. The levels of succinate dehydrogenase (SDH) and muscle glycogen (MG) in the tibia muscle of rats were detected by the corresponding kits, as well as the expression of related genes/proteins were assessed by real-time quantitative PCR (RT-qPCR) and western blot.

RESULTS

HE staining suggested that MY suppressed the symptoms of OA, which was abolished by AMPK inhibitor. Furthermore, the SDH and MG contents in the OA + MY + AMPK inhibitor group were lower than in the OA + MY group. At last, the levels of AMPK, PI3K, AKT1, Ldh, Myod, Chrna1, and Chrnd were notably decreased after AMPK inhibitor treatment, while the levels of Lcad and Mcad were up-regulated by AMPK inhibitor. Furthermore, their protein expression levels detected by western blot were consistent with those from RT-qPCR.

CONCLUSION

MY may partially regulate skeletal muscle changes and prevente OA development through the AMPK pathway.

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.

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 the protective effects of chondroitin sulfate oligosaccharide against osteoarthritis via inactivation of NLRP3 inflammasome by in vivo and in vitro studies

Osteoarthritis (OA) is the most prevalent degenerative arthritis disease linked to aging, obesity, diet, and accumulation of octacalcium phosphate (OCP) crystals in joints. Current research has focused on inflammation and chondrocytes apoptosis as underlying OA mechanisms. Inflammatory cytokines like IL-1β activate matrix metalloproteinase-13 (MMP-13) and aggrecanase (the member of A Disintegrin and Metalloproteinase with Thrombospondin motifs family, ADAMTS), leading to cartilage matrix degradation. The NLRP3 inflammasome also contributes to OA pathogenesis by maturing IL-1β. Natural products like chondroitin sulfate oligosaccharides (oligo-CS) show promise in OA treatment by inhibiting inflammation. Our study evaluates the protective effects of oligo-CS against OA by targeting NLRP3 inflammation. Stimulating human SW1353 chondrocytes and human mononuclear macrophage THP-1 cells with OCP showed increased NLRP3 inflammation initiation, NF-κB pathway activation, and the production of inflammatory cytokines (IL-1β, IL-6) and the metabolic index (MMP-13, ADAMTS-5), leading to cartilage matrix degradation. However, oligo-CS treatment significantly reduced inflammation. In a 28-day in vivo study with C57BL/6 female mice, OCP was injected into their right knee and oligo-CS was orally administered. The OCP group exhibited significant joint space narrowing and chondrocyte loss, while the oligo-CS group maintained cartilage integrity. Oligo-CS groups also regulated gut microbiota composition to a healthier state. Taken together, our findings suggest that oligo-CS can be considered as a protective compound against OA.

Gut microbiota alterations in adolescent idiopathic scoliosis: a comparison study with healthy control and congenital scoliosis

PURPOSE

This study aims to compare the composition of GM isolated from individuals with AIS or congenital scoliosis (CS) and age-matched control (Ctr).

METHODS

A total of 48 patients with AIS, 24 patients with CS, and 31 healthy individuals were recruited as the discovery cohort, and 9 pairs of siblings where one was affected by AIS were recruited as the validation cohort. The GM profile was determined with 16S rRNA sequencing, and the alpha-diversity and beta-diversity metrics were performed with Mothur. Linear discriminant analysis (LDA) analysis was performed to identify the enriched species.

RESULTS

The α diversity (Chao1 index) was significantly lower in AIS patients with low BMI (< 18.5) than those with normal BMI. The PcoA analysis showed a trend of clustering of GM in AIS compared to that in Ctr and CS groups (r2 = 0.0553, p = 0.001). METASTAT analysis showed Cellulomonadaceae was significantly enriched in AIS groups compared to CS and Ctr. LDA analysis showed 9 enriched species in AIS patients. Compared to Ctr, two species including Hungatella genus and Bacteroides fragilis were significantly enriched, while the Firmicutes versus Bacteroidetes (F/B) ratio and the Ruminococcus genus were significantly decreased in AIS but not CS groups. The significantly reduced F/B ratio and Ruminococcus genus in AIS were replicated in the validation cohort.

CONCLUSIONS

Our study elucidated an association between low BMI and GM diversity in AIS patients. The reduced F/B ratio and Ruminococcus genus in AIS patients were identified and validated in 9 pairs of AIS patients and their unaffected siblings. Our pilot results may help understand the anthropometric discrepancy in these patients and support a possible role of GM in the pathogenesis of AIS.

Association between body roundness index and risk of osteoarthritis: a cross-sectional study

BACKGROUND

The link between body roundness index (BRI) and osteoarthritis (OA) has yet to be validated. Our aim was to explore this connection between BRI and OA risk.

METHODS

This cross-sectional study utilized the 1999-2018 National Health and Nutrition Examination Survey retrieved data. To assess the association between BRI and OA risk, we performed weighted multivariable regression analysis (MVRA), with smooth curve fitting for potential nonlinear association and subgroup analysis and interaction tests for relationships in specific subgroups. A 7:3 ratio was adopted for the random division of the acquired data into training and validation sets. Subsequently, least absolute shrinkage and selection operator regression, along with MVRA, were conducted for the training set to isolate variables for a prediction model. This model was visualized using the nomogram and was followed by evaluation. Finally, the validation set was utilized to validate the model.

RESULTS

This study enrolled 12,946 individuals. Following the adjustment for all covariables, OA risk increased by 18% with every unit rise in BRI (odd ratio [OR] = 1.18; 95% confidence interval [CI]: 1.13-1.23; P < 0.0001). Upon regarding BRI as a categorical variable, it was divided into quartiles for subsequent analysis. In comparison to quartile 1, the risk of OA was increased in quartile 2 (OR = 1.58; 95% CI: 1.22-2.03; P = 0.0006), quartile 3 (OR = 1.83; 95% CI: 1.40-2.40; P < 0.0001) and quartile 4 (OR = 2.70; 95% CI: 1.99-3.66; P < 0.0001). Smooth curve fitting revealed no non-linear relationships. None of the subgroups showed a statistically significant interaction (all P > 0.05). After selecting the variables, a prediction model was developed. The prediction model exhibited favorable discriminatory power, high accuracy, and potential clinical benefits in training and validation sets.

CONCLUSIONS

The BRI was positively associated with OA risk. Our predictive model demonstrated that combining BRI with other easily accessible factors was helpful in assessing and managing high-risk OA groups.

Basal metabolic rate mediates the causal relationship between gut microbiota and osteoarthritis: a two-step bidirectional Mendelian randomization study

Background

The relationship between gut microbiota and osteoarthritis (OA) occurrence remains unclear. Existing research needs to clearly understand how basal metabolic rate (BMR) regulates this relationship. Therefore, using a two-step bidirectional Mendelian Randomization approach, our study aims to investigate whether BMR levels mediate the causal relationship between gut microbiota and OA.

Methods

In this study, we examined publicly available summary statistics from Genome-Wide Association Studies (GWAS) to determine the correlation between gut microbiota and OA. The analysis included one primary dataset and two secondary datasets. Initially, a two-step, two-sample, and reverse MR analysis was performed to identify the causal relationship between gut microbiota and OA. Subsequently, a two-step MR analysis revealed that the relationship between microbiota and OA is mediated by BMR. Sensitivity analyses confirmed the robustness of the study results.

Results

In our analysis of the primary dataset, we discovered a positive correlation between three taxa and the outcome of OA, and eight taxa exhibited a negative correlation with the OA outcome. Through comparisons with the secondary dataset and multiple testing corrections, we found a negative association between the class Actinobacteria (OR=0.992886277, p-value = 0.003) and the likelihood of OA occurrence. Notably, knee osteoarthritis (KOA) and hip osteoarthritis (HOA) had a strong negative correlation (OR = 0.927237553/0.892581219). Our analysis suggests that BMR significantly mediates the causal pathway from Actinobacteria to OA, with a mediated effect of 2.59%. Additionally, BMR mediates 3.98% of the impact in the path from the order Bifidobacteriales and the family Bifidobacteriaceae to OA. Besides these findings, our reverse analysis did not indicate any significant effect of OA on gut microbiota or BMR.

Conclusion

Our research results indicate that an increase in the abundance of specific gut microbial taxa is associated with a reduced incidence of OA, and BMR levels mediate this causal relationship. Further large-scale randomized controlled trials are necessary to validate the causal impact of gut microbiota on the risk of OA. This study provides new insights into the potential prevention of OA by modulating the gut microbiota.

The connection between aging, cellular senescence and gut microbiome alterations: A comprehensive review

The intricate interplay between cellular senescence and alterations in the gut microbiome emerges as a pivotal axis in the aging process, increasingly recognized for its contribution to systemic inflammation, physiological decline, and predisposition to age-associated diseases. Cellular senescence, characterized by a cessation of cell division in response to various stressors, induces morphological and functional changes within tissues. The complexity and heterogeneity of senescent cells, alongside the secretion of senescence-associated secretory phenotype, exacerbate the aging process through pro-inflammatory pathways and influence the microenvironment and immune system. Concurrently, aging-associated changes in gut microbiome diversity and composition contribute to dysbiosis, further exacerbating systemic inflammation and undermining the integrity of various bodily functions. This review encapsulates the burgeoning research on the reciprocal relationship between cellular senescence and gut dysbiosis, highlighting their collective impact on age-related musculoskeletal diseases, including osteoporosis, sarcopenia, and osteoarthritis. It also explores the potential of modulating the gut microbiome and targeting cellular senescence as innovative strategies for healthy aging and mitigating the progression of aging-related conditions. By exploring targeted interventions, including the development of senotherapeutic drugs and probiotic therapies, this review aims to shed light on novel therapeutic avenues. These strategies leverage the connection between cellular senescence and gut microbiome alterations to advance aging research and development of interventions aimed at extending health span and improving the quality of life in the older population.

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.

Transcriptomics and metabolomics: Challenges of studying obesity in osteoarthritis

Objective

Obesity is a leading risk factor for both the incidence and progression of osteoarthritis (OA). Omic technologies, including transcriptomics and metabolomics are capable of identifying RNA and metabolite profiles in tissues and biofluids of OA patients. The objective of this review is to highlight studies using transcriptomics and metabolomics that contribute to our understanding of OA pathology in relation to obesity.

Design

We conducted a targeted search of PUBMED for articles, and GEO for datasets, published up to February 13, 2024, screening for those using high-throughput transcriptomic and metabolomic techniques to study human or pre-clinical animal model tissues or biofluids related to obesity-associated OA. We describe relevant studies and discuss challenges studying obesity as a disease-related factor in OA.

Results

Of the 107 publications identified by our search criteria, only 15 specifically used transcriptomics or metabolomics to study joint tissues or biofluids in obesity-related OA. Specific transcriptomic and metabolomic signatures associated with obesity-related OA have been defined in select local joint tissues, biofluids and other biological material. However, considerable challenges exist in understanding contributions of obesity-associated modifications of transcriptomes and metabolomes related to OA, including sociodemographic, anthropometric, dietary and molecular redundancy-related factors.

Conclusions

A number of additional transcriptomic and metabolomic studies are needed to comprehensively understand how obesity affects OA incidence, progression and outcomes. Integration of transcriptome and metabolome signatures from multiple tissues and biofluids, using network-based approaches will likely help to better define putative therapeutic targets that could enable precision medicine approaches to obese OA patients.

Effect of prebiotic fiber on physical function and gut microbiota in adults, mostly women, with knee osteoarthritis and obesity: a randomized controlled trial

PURPOSE

Obesity is a primary risk factor for knee osteoarthritis (OA). Prebiotics enhance beneficial gut microbes and can reduce body fat and inflammation. Our objective was to examine if a 6-month prebiotic intervention improved physical function in adults with knee osteoarthritis and obesity. We also measured knee pain, body composition, quality of life, gut microbiota, inflammatory markers, and serum metabolomics.

METHODS

Adults (n = 54, mostly women) with co-morbid obesity (BMI > 30 kg/m2) and unilateral/bilateral knee OA were randomly assigned to prebiotic (oligofructose-enriched inulin; 16 g/day; n = 31) or isocaloric placebo (maltodextrin; n = 21) for 6 months. Performance based-tests, knee pain, quality of life, serum metabolomics and inflammatory markers, and fecal microbiota and short-chain fatty acids were assessed.

RESULTS

Significant between group differences were detected for the change in timed-up-and-go test, 40 m fast paced walk test, and hand grip strength test from baseline that favored prebiotic over placebo. Prebiotic also reduced trunk fat mass (kg) at 6 months and trunk fat (%) at 3 months compared to placebo. There was a trend (p = 0.059) for reduced knee pain at 6 months with prebiotic versus placebo. In gut microbiota analysis, a total of 37 amplicon sequence variants differed between groups. Bifidobacterium abundance was positively correlated with distance walked in the 6-min walk test and hand grip strength. At 6 months, there was a significant separation of serum metabolites between groups with upregulation of phenylalanine and tyrosine metabolism with prebiotic.

CONCLUSION

Prebiotics may hold promise for conservative management of knee osteoarthritis in adults with obesity and larger trials are warranted.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov/study/NCT04172688.

Association between Dietary total antioxidant capacity and knee osteoarthritis: a case-control study in the Iranian Population

AIM

Knee osteoarthritis (KOA) is a prevalent chronic condition associated with significant pain, disability, and healthcare costs, particularly among the elderly population. Despite the considerable burden of KOA, effective treatment options for managing the condition's underlying causes remain limited. This case-control study aims to investigate the relationship between dietary total antioxidant capacity (DTAC) and knee osteoarthritis.

METHODS

This case-control study was conducted on 105 patients with confirmed KOA and 210 controls. KOA was diagnosed based on the American College of Rheumatology criteria. Dietary total antioxidant capacity (DTAC) was calculated based on the ferric-reducing antioxidant power method.

RESULTS

The mean age and BMI of the participants were 53.6 ± 8.8 years old and 27.3 ± 2.7 kg/m2, respectively. The study participant's DTAC score ranged from 3.56 to 25.32 with a mean and SD of 12.46 ± 5.12. In the crude model, individuals in the highest quartile of DTAC score had 71% lower odds of having knee osteoarthritis compared to those in the first quartile (OR: 0.29, 95%CI: 0.15 to 0.58, P-trend < 0.001). These associations remained significant after adjustment for potential confounders including age, sex, energy intake, family history of osteoarthritis, vitamin D and calcium use, physical activity level, cigarette smoking and BMI. Although the odds of having knee osteoarthritis decreased with increasing quartiles of DTAC in both sexes, this relationship was stronger among males than females.

CONCLUSION

The results of this study showed that there was an inverse correlation between DTAC and KOA among the Iranian patients with KOA.

Microbiota-bone axis in ageing-related bone diseases

Bone homeostasis in physiology depends on the balance between bone formation and resorption, and in pathology, this homeostasis is susceptible to disruption by different influences, especially under ageing condition. Gut microbiota has been recognized as a crucial factor in regulating host health. Numerous studies have demonstrated a significant association between gut microbiota and bone metabolism through host-microbiota crosstalk, and gut microbiota is even an important factor in the pathogenesis of bone metabolism-related diseases that cannot be ignored. This review explores the interplay between gut microbiota and bone metabolism, focusing on the roles of gut microbiota in bone ageing and aging-related bone diseases, including osteoporosis, fragility fracture repair, osteoarthritis, and spinal degeneration from different perspectives. The impact of gut microbiota on bone metabolism during aging through modification of endocrinology system, immune system and gut microbiota metabolites are summarized, facilitating a better grasp of the pathogenesis of aging-related bone metabolic diseases. This review offers innovative insights into targeting the gut microbiota for the treatment of bone ageing-related diseases as a clinical therapeutic strategy.

Mapping knowledge landscapes and research frontiers of gastrointestinal microbiota and bone metabolism: a text-mining study

Introduction

Extensive research efforts have been dedicated to elucidating the intricate pathways by which gastrointestinal microbiota and their metabolites exert influence on the processes of bone formation. Nonetheless, a notable gap exists in the literature concerning a bibliometric analysis of research trends at the nexus of gastrointestinal microbiota and bone metabolism.

Methods

To address this scholarly void, the present study employs a suite of bibliometric tools including online platforms, CiteSpace and VOSviewer to scrutinize the pertinent literature in the realm of gastrointestinal microbiota and bone metabolism.

Results and discussion

Examination of the temporal distribution of publications spanning from 2000 to 2023 reveals a discernible upward trajectory in research output, characterized by an average annual growth rate of 19.2%. Notably, China and the United States emerge as primary contributors. Predominant among contributing institutions are Emory University, Harvard University, and the University of California. Pacifici R from Emory University contributed the most research with 15 publications. In the realm of academic journals, Nutrients emerges as the foremost publisher, followed closely by Frontiers in Microbiology and PLOS One. And PLOS One attains the highest average citations of 32.48. Analysis of highly cited papers underscores a burgeoning interest in the therapeutic potential of probiotics or probiotic blends in modulating bone metabolism by augmenting host immune responses. Notably, significant research attention has coalesced around the therapeutic interventions of probiotics, particularly Lactobacillus reuteri, in osteoporosis, as well as the role of gastrointestinal microbiota in the etiology and progression of osteoarthritis. Keyword analysis reveals prevalent terms including gut microbiota, osteoporosis, bone density, probiotics, inflammation, SCFAs, metabolism, osteoarthritis, calcium absorption, obesity, double-blind, prebiotics, mechanisms, postmenopausal women, supplementation, risk factors, oxidative stress, and immune system. Future research endeavors warrant a nuanced exploration of topics such as inflammation, obesity, SCFAs, postmenopausal osteoporosis, skeletal muscle, oxidative stress, double-blind trials, and pathogenic mechanisms. In summary, this study presents a comprehensive bibliometric analysis of global research on the interplay between gastrointestinal microbiota and bone metabolism, offering valuable insights for scholars, particularly nascent researchers, embarking on analogous investigations within this domain.

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.

Early Outcomes of Orthopedic Pre-surgical Patients Enrolled in an Intensive, Interprofessional Lifestyle Medicine Program to Optimize Health

Recently, lifestyle medicine (LSM) application has shown feasibility for musculoskeletal pain patients with co-existing lifestyle-related chronic diseases. This study describes early results of a LSM program for musculoskeletal patients with goals to optimize health prior to orthopedic surgery. Fifty-four patients (age: 61 ± 11 years; 39 [72%] females) completed the program from 3/8/22-12/1/23. Data included patient goals, utilization, goal attainment, and patient outcomes. Most patients (41/54 [76%]) enrolled with established surgical dates. Mean BMI was 43.2 ± 5.3 kg/m2, and 89% had ≥2 lifestyle-related chronic diseases. The majority reported impaired sleep (79%) and zero cumulative minutes of physical activity/week (57%). Mean program duration was 13 ± 8 weeks involving 5 ± 4 visits with members of the interprofessional team. Fifty-two (96%) patients successfully attained pre-program goals, and 49/54 (91%) met their surgical goal. Of the patients enrolled without surgical dates, 11/13 (85%) optimized their health and proceeded to surgery. Forty-two (78%) patients reported decreases in weight and BMI, averaging 11 ± 7 lbs and 1.8 ± 1.3 kg/m2, respectively. Rates of improvement in pain, PROMIS-10 physical and mental health, and PHQ-4 were 52%, 37%, 45%, and 47%, respectively. These data demonstrate the feasibility and effectiveness of a LSM program to address whole-person health optimization and enable orthopedic patients to improve lifestyle behaviors and proceed to orthopedic surgery.

Dietary fiber may benefit chondrocyte activity maintenance

The understanding of the link between the gut-bone axis is growing yearly, but the mechanisms involved are not yet clear. Our study analyzed the role of Sestrin2 (SESN2)pathway in the gut-bone axis. We established an osteoarthritis (OA) model in Sprague-Dawley (SD) rats using the anterior cruciate ligament transection (ACLT) procedure, followed by a dietary intervention with varying levels of dietary fiber content for 8 weeks. By 16S rRNA sequencing of the gut microbiota, we found that high dietary fiber (HDF) intake could significantly increase the Bacillota-dominant gut microbiota. Meanwhile, enzyme linked immunosorbent assay (ELISA) and histological analysis showed that intervention with HDF could reduce the degree of bone and joint lesions and inflammation. We hypothesize that HDF increased the dominant flora of Bacillota, up-regulated the expression of SESN2 in knee joint, and reduced gut permeability, thereby reducing systemic inflammatory response and the degree of bone and joint lesions. Therefore, the present study confirms that changes in gut microbiota induced by increased dietary fiber intake delayed the onset of OA by promoting up-regulation of SESN2 expression at the knee joint to maintain chondrocyte activity and reduce synovial inflammation.

Pterostilbene Protects against Osteoarthritis through NLRP3 Inflammasome Inactivation and Improves Gut Microbiota as Evidenced by In Vivo and In Vitro Studies

Osteoarthritis (OA) is a persistent inflammatory disease, and long-term clinical treatment often leads to side effects. In this study, we evaluated pterostilbene (PT), a natural anti-inflammatory substance, for its protective effects and safety during prolonged use on OA. Results showed that PT alleviated the loss of chondrocytes and widened the narrow joint space in an octacalcium phosphate (OCP)-induced OA mouse model (n = 3). In vitro experiments demonstrate that PT reduced NLRP3 inflammation activation (relative protein expression: C: 1 ± 0.09, lipopolysaccharide (LPS): 1.14 ± 0.07, PT: 0.91 ± 0.07, LPS + PT: 0.68 ± 0.04) and the release of inflammatory cytokines through NF-κB signaling inactivation (relative protein expression: C: 1 ± 0.03, LPS: 3.49 ± 0.02, PT: 0.66 ± 0.08, LPS + PT: 2.78 ± 0.05), ultimately preventing cartilage catabolism. Interestingly, PT also altered gut microbiota by reducing inflammation-associated flora and increasing the abundance of healthy bacteria in OA groups. Collectively, these results suggest that the PT can be considered as a protective strategy for OA.

Collagen type X expression and chondrocyte hypertrophic differentiation during OA and OS development

Chondrocyte hypertrophy and the expression of its specific marker, the collagen type X gene (COL10A1), constitute key terminal differentiation stages during endochondral ossification in long bone development. Mutations in the COL10A1 gene are known to cause schmid type metaphyseal chondrodysplasia (SMCD) and spondyloepiphyseal dyschondrodysplasia (SMD). Moreover, abnormal COL10A1 expression and aberrant chondrocyte hypertrophy are strongly correlated with skeletal diseases, notably osteoarthritis (OA) and osteosarcoma (OS). Throughout the progression of OA, articular chondrocytes undergo substantial changes in gene expression and phenotype, including a transition to a hypertrophic-like state characterized by the expression of collagen type X, matrix metalloproteinase-13, and alkaline phosphatase. This state is similar to the process of endochondral ossification during cartilage development. OS, the most common pediatric bone cancer, exhibits characteristics of abnormal bone formation alongside the presence of tumor tissue containing cartilaginous components. This observation suggests a potential role for chondrogenesis in the development of OS. A deeper understanding of the shifts in collagen X expression and chondrocyte hypertrophy phenotypes in OA or OS may offer novel insights into their pathogenesis, thereby paving the way for potential therapeutic interventions. This review systematically summarizes the findings from multiple OA models (e.g., transgenic, surgically-induced, mechanically-loaded, and chemically-induced OA models), with a particular focus on their chondrogenic and/or hypertrophic phenotypes and possible signaling pathways. The OS phenotypes and pathogenesis in relation to chondrogenesis, collagen X expression, chondrocyte (hypertrophic) differentiation, and their regulatory mechanisms were also discussed. Together, this review provides novel insights into OA and OS therapeutics, possibly by intervening the process of abnormal endochondral-like pathway with altered collagen type X expression.

Murine cartilage microbial DNA deposition occurs rapidly following the introduction of a gut microbiome and changes with obesity, aging, and knee osteoarthritis

Cartilage microbial DNA patterns have been recently characterized in osteoarthritis (OA). The objectives of this study were to evaluate the gut origins of cartilage microbial DNA, to characterize cartilage microbial changes with age, obesity, and OA in mice, and correlate these to gut microbiome changes. We used 16S rRNA sequencing performed longitudinally on articular knee cartilage from germ-free (GF) mice following oral microbiome inoculation and cartilage and cecal samples from young and old wild-type mice with/without high-fat diet-induced obesity (HFD) and with/without OA induced by destabilization of the medial meniscus (DMM) to evaluate gut and cartilage microbiota. Microbial diversity was assessed, groups compared, and functional metagenomic profiles reconstructed. Findings were confirmed in an independent cohort by clade-specific qPCR. We found that cartilage microbial patterns developed at 48 h and later timepoints following oral microbiome inoculation of GF mice. Alpha diversity was increased in SPF mouse cartilage samples with age (P = 0.013), HFD (P = 5.6E-4), and OA (P = 0.029) but decreased in cecal samples with age (P = 0.014) and HFD (P = 1.5E-9). Numerous clades were altered with aging, HFD, and OA, including increases in Verrucomicrobia in both cartilage and cecal samples. Functional analysis suggested changes in dihydroorotase, glutamate-5-semialdehyde dehydrogenase, glutamate-5-kinase, and phosphoribosylamine-glycine ligase, in both cecum and cartilage, with aging, HFD, and OA. In conclusion, cartilage microbial DNA patterns develop rapidly after the introduction of a gut microbiome and change in concert with the gut microbiome during aging, HFD, and OA in mice. DMM-induced OA causes shifts in both cartilage and cecal microbiome patterns independent of other factors.

Maternal nanoplastic ingestion induces an increase in offspring body weight through altered lipid species and microbiota

The rapidly increasing prevalence of obesity and overweight, especially in children and adolescents, has become a serious societal issue. Although various genetic and environmental risk factors for pediatric obesity and overweight have been identified, the problem has not been solved. In this study, we examined whether environmental nanoplastic (NP) pollutants can act as environmental obesogens using mouse models exposed to NPs derived from polystyrene and polypropylene, which are abundant in the environment. We found abnormal weight gain in the progeny until 6 weeks of age following the oral administration of NPs to the mother during gestation and lactation. Through a series of experiments involving multi-omic analyses, we have demonstrated that NP-induced weight gain is caused by alterations in the lipid composition (lysophosphatidylcholine/phosphatidylcholine ratio) of maternal breast milk and he gut microbiota distribution of the progeny. These data indicate that environmental NPs can act as obesogens in childhood.

OA susceptibility in mice is partially mediated by the gut microbiome, is transferrable via microbiome transplantation and is associated with immunophenotype changes

OBJECTIVES

The Murphy Roths Large (MRL)/MpJ 'superhealer' mouse strain is protected from post-traumatic osteoarthritis (OA), although no studies have evaluated the microbiome in the context of this protection. This study characterised microbiome differences between MRL and wild-type mice, evaluated microbiome transplantation and OA and investigated microbiome-associated immunophenotypes.

METHODS

Cecal material from mixed sex C57BL6/J (B6) or female MRL/MpJ (MRL) was transplanted into B6 and MRL mice, then OA was induced by disruption of the medial meniscus surgery (DMM). In other experiments, transplantation was performed after DMM and transplantation was performed into germ-free mice. Transplanted mice were bred through F2. OARSI, synovitis and osteophyte scores were determined blindly 8 weeks after DMM. 16S microbiome sequencing was performed and metagenomic function was imputed. Immunophenotypes were determined using mass cytometry.

RESULTS

MRL-into-B6 transplant prior to DMM showed reduced OA histopathology (OARSI score 70% lower transplant vs B6 control), synovitis (60% reduction) and osteophyte scores (30% reduction) 8 weeks after DMM. When performed 48 hours after DMM, MRL-into-B6 transplant improved OA outcomes but not when performed 1-2 weeks after DMM. Protection was seen in F1 (60% reduction) and F2 progeny (30% reduction). Several cecal microbiome clades were correlated with either better (eg, Lactobacillus, R=-0.32, p=0.02) or worse (eg, Rikenellaceae, R=0.43, p=0.001) OA outcomes. Baseline immunophenotypes associated with MRL-into-B6 transplants and MRL included reduced double-negative T cells and increased CD25+CD4+ T cells.

CONCLUSION

The gut microbiome is responsible in part for OA protection in MRL mice and is transferrable by microbiome transplantation. Transplantation induces resting systemic immunophenotyping changes that correlate with OA protection.

Chondroprotective effects of bone marrow mesenchymal stem cell-derived exosomes in osteoarthritis

Chondrocyte ferroptosis constitutes a major cause of the development of osteoarthritis (OA). Bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) have a protective role against ferroptosis in various diseases. Hence, we aimed to determine whether BMSC-Exos alleviated chondrocyte ferroptosis and its effect on OA, and to dissect out the possible mechanisms. An OA rat chondrocyte model was established by interleukin-1β (IL-1β) exposure, and treated with BMSC-Exos/ferroptosis inhibitor Ferrostatin-1. Cell viability/ferroptosis-related index levels [reactive oxygen species (ROS)/malondialdehyde (MDA)/glutathione (GSH)]/cell death/ACSL4 mRNA and protein levels and METTL3 levels were assessed by MTT/kits/immunohistochemical method and TUNEL staining/RT-qPCR and Western blot. METTL3/ACSL4 were overexpressed in rat chondrocytes to evaluate their role in BMSC-Exo-produced repression on chondrocyte ferroptosis. Bioinformatics website predicted the presence of m6A modification sites on ACSL4 mRNA, with the m6A level enriched on it assessed by MeRIP/RT-qPCR. ACSL4 mRNA stability was detected by actinomycin D assay. A surgical destabilized medial meniscus rat OA model was also established, followed by injection with BMSC-Exos to verify their function. IL-1β stimulation in rat chondrocytes inhibited cell viability, elevated Fe2+/ROS/MDA levels, declined GSH levels and increased TUNEL positive cell number and ACSL4 level, which were neutralized by BMSC-Exos. BMSC-Exos limited chondrocyte ferroptosis by down-regulating METTL3, with the effect abrogated by METTL3 overexpression. METTL3 regulated the m6A modification of ACSL4 mRNA, increasing ACSL4 mRNA stability and ACSL4 expression. BMSC-Exos reduced chondrocyte ferroptosis and prevented OA progression via disruption of the METTL3-m6A-ACSL4 axis. BMSC-Exos might exert a chondroprotective effect by attenuating chondrocyte ferroptosis and alleviate OA progression.

Unraveling the gut-Lung axis: Exploring complex mechanisms in disease interplay

The link between gut and lung starts as early as during organogenesis. Even though they are anatomically distinct, essential bidirectional crosstalk via complex mechanisms supports GLA. Emerging studies have demonstrated the association of gut and lung diseases via multifaceted mechanisms. Advancements in omics and metagenomics technologies revealed a potential link between gut and lung microbiota, adding further complexity to GLA. Despite substantial studies on GLA in various disease models, mechanisms beyond microbial dysbiosis regulating the interplay between gut and lung tissues during disease conditions are not thoroughly reviewed. This review outlines disease specific GLA mechanisms, emphasizing research gaps with a focus on gut-to-lung direction based on current GLA literature. Moreover, the review discusses potential gut microbiota and their products like metabolites, immune modulators, and non-bacterial contributions as a basis for developing treatment strategies for lung diseases. Advanced experimental methods, modern diagnostic tools, and technological advancements are also highlighted as crucial areas for improvement in developing novel therapeutic approaches for GLA-related diseases. In conclusion, this review underscores the importance of exploring additional mechanisms within the GLA to gain a deeper understanding that could aid in preventing and treating a wide spectrum of lung diseases.

Bioactives and their roles in bone metabolism of osteoarthritis: evidence and mechanisms on gut-bone axis

Bioactives significantly modify and maintain human health. Available data suggest that Bioactives might play a beneficial role in chronic inflammatory diseases. Although promised, defining their mechanisms and opting to weigh their benefits and limitations is imperative. Detailed mechanisms by which critical Bioactives, including probiotics and prebiotics such as dietary lipids (DHA, EPA, alpha LA), vitamin D, polysaccharides (fructooligosaccharide), polyphenols (curcumin, resveratrol, and capsaicin) potentially modulate inflammation and bone metabolism is limited. Certain dietary bioactive significantly impact the gut microbiota, immune system, and pain response via the gut-immune-bone axis. This narrative review highlights a recent update on mechanistic evidence that bioactive is demonstrated demonstrated to reduce osteoarthritis pathophysiology.

Microbiome's role in musculoskeletal health through the gut-bone axis insights

The interplay between the human microbiome and the musculoskeletal system represents a burgeoning field of research with profound implications for understanding and treating musculoskeletal disorders. This review articulates the pivotal role of the microbiome in modulating bone health, highlighting the gut-bone axis as a critical nexus for potential therapeutic intervention. Through a meticulous analysis of recent clinical research, we underscore the microbiome's influence on osteoporosis, sarcopenia, osteoarthritis, and rheumatoid arthritis, delineating both the direct and indirect mechanisms by which microbiota could impact musculoskeletal integrity and function. Our investigation reveals novel insights into the microbiota's contribution to bone density regulation, hormone production, immune modulation, and nutrient absorption, laying the groundwork for innovative microbiome-based strategies in musculoskeletal disease management. Significantly, we identify the challenges hindering the translation of research into clinical practice, including the limitations of current microbial sequencing techniques and the need for standardized methodologies in microbiome studies. Furthermore, we highlight promising directions for future research, particularly in the realm of personalized medicine, where the microbiome's variability offers unique opportunities for tailored treatment approaches. This review sets a new agenda for leveraging gut microbiota in the diagnosis, prevention, and treatment of musculoskeletal conditions, marking a pivotal step toward integrating microbiome science into clinical musculoskeletal care.

Pathogenic Mechanisms and Therapeutic Approaches in Obesity-Related Knee Osteoarthritis

The knee is the joint most frequently involved in osteoarthritis, a common joint disorder in the adult population that is associated with significant chronic joint pain, reduced mobility and quality of life. Recent studies have established an association between obesity and the development of knee osteoarthritis that goes beyond the increased mechanical load on the knees as weight-bearing joints. This link is based on the maintenance of a chronic low-grade inflammation, altered secretion of adipokines by the adipose tissue and development of sarcopenia. Major adipokines involved in the pathogenesis of obesity-related knee osteoarthritis include adiponectin, which appears to have a protective effect, as well as leptin, resistin and visfatin, which are associated with higher pain scores and more severe structural damage. Joint pain in knee osteoarthritis may be both nociceptive and neuropathic and is the result of complex mechanisms driven by nerve growth factor, calcitonin gene-related peptide and pro-inflammatory cytokines. The role of endogenous cannabinoids and gut microbiota in common mechanisms between obesity and knee pain has recently been studied. The aim of the present review is to highlight major pathogenic mechanisms in obesity-related knee osteoarthritis with special attention on pain and to comment on possible therapeutic approaches.

Gut-joint axis in knee synovitis: gut fungal dysbiosis and altered fungi-bacteria correlation network identified in a community-based study

OBJECTIVES

Knee synovitis is a highly prevalent and potentially curable condition for knee pain; however, its pathogenesis remains unclear. We sought to assess the associations of the gut fungal microbiota and the fungi-bacteria correlation network with knee synovitis.

METHODS

Participants were derived from a community-based cross-sectional study. We performed an ultrasound examination of both knees. A knee was defined as having synovitis if its synovium was ≥4 mm and/or Power Doppler (PD) signal was within the knee synovium area (PD synovitis). We collected faecal specimens from each participant and assessed gut fungal and bacterial microbiota using internal transcribed spacer 2 and shotgun metagenomic sequencing. We examined the relation of α-diversity, β-diversity, the relative abundance of taxa and the interkingdom correlations to knee synovitis.

RESULTS

Among 977 participants (mean age: 63.2 years; women: 58.8%), 191 (19.5%) had knee synovitis. β-diversity of the gut fungal microbiota, but not α-diversity, was significantly associated with prevalent knee synovitis. The fungal genus Schizophyllum was inversely correlated with the prevalence and activity (ie, control, synovitis without PD signal and PD synovitis) of knee synovitis. Compared with those without synovitis, the fungi-bacteria correlation network in patients with knee synovitis was smaller (nodes: 93 vs 153; edges: 107 vs 244), and the average number of neighbours was fewer (2.3 vs 3.2).

CONCLUSION

Alterations of gut fungal microbiota and the fungi-bacteria correlation network are associated with knee synovitis. These novel findings may help understand the mechanisms of the gut-joint axis in knee synovitis and suggest potential targets for future treatment.

Programming of metabolic and autoimmune diseases in canine and feline: linkage to the gut microbiome

Metabolic and autoimmune disorders have long represented challenging health problems because of their growing prevalence in companion animals. The gut microbiome, made up of trillions of microorganisms, is implicated in multiple physiological and pathological processes. Similar to human beings, the complicated microbiome harbored in the gut of canines and felines emerges as a key factor determining a wide range of normal and disease conditions. Evidence accumulated from recent findings on canine and feline research uncovered that the gut microbiome is actively involved in host metabolism and immunity. Notably, the composition, abundance, activity, and metabolites of the gut microbiome are all elements that shape clinical outcomes concerning metabolism and immune function. This review highlights the implications of the gut microbiome for metabolic disorders (obesity, diabetes, and hepatic lipidosis) and autoimmune diseases (inflammatory bowel disease, osteoarthritis, asthma, and myasthenia gravis) in canine and feline animals, providing novel strategies and therapeutic targets for the prevention and treatment of pet diseases.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Relationship of Chronic Systemic Inflammation to Both Chronic Lifestyle-Related Diseases and Osteoarthritis: The Case for Lifestyle Medicine for Osteoarthritis

Systemic inflammation is a root cause of lifestyle-related chronic diseases and may also play a role in the development and progression of osteoarthritis (OA). Lifestyle medicine seeks to treat, prevent, and reverse lifestyle-related chronic disease via 6 pillars: nutrition, sleep health, stress management, physical activity, social connections, and risky behavior avoidance/reduction. This article presents a review of the literature in which we assess the connections between the 6 pillars of lifestyle medicine, chronic systemic inflammation, and OA. We also discuss the whole-person approach that lifestyle medicine interventions can provide to reduce chronic systemic inflammation and affect the development or progression of OA.

The Role of Nutrition in Osteoarthritis Development

Osteoarthritis (OA) prevalence has increased 113% since 1990, and currently more than half a billion people worldwide are living with this slowly progressing, degenerative joint disease [...].

Tripterygium hypoglaucum extract ameliorates adjuvant-induced arthritis in mice through the gut microbiota

Traditionally, Tripterygium hypoglaucum (Levl.) Hutch (THH) are widely used in Chinese folk to treat rheumatoid arthritis (RA). This study aimed to investigate whether the anti-RA effect of THH is related with the gut microbiota. The main components of prepared THH extract were identified by HPLC-MS. C57BL/6 mice with adjuvant-induced arthritis (AIA) were treated with THH extract by gavage for one month. THH extract significantly alleviated swollen ankle, joint cavity exudation, and articular cartilage destruction in AIA mice. The mRNA and protein levels of inflammatory mediators in muscles and plasma indicated that THH extract attenuated inflammatory responses in the joint by blocking TLR4/MyD88/MAPK signaling pathways. THH extract remarkably restored the dysbiosis of the gut microbiota in AIA mice, featuring the increases of Bifidobacterium, Akkermansia, and Lactobacillus and the decreases of Butyricimonas, Parabacteroides, and Anaeroplasma. Furthermore, the altered bacteria were closely correlated with physiological indices and drove metabolic changes of the intestinal microbiota. In addition, antibiotic-induced pseudo germ-free mice were employed to verify the role of the intestinal flora. Strikingly, THH treatment failed to ameliorate the arthritis symptoms and signaling pathways in pseudo germ-free mice, which validates the indispensable role of the intestinal flora. For the first time, we demonstrated that THH extract protects joint inflammation by manipulating the intestinal flora and regulating the TLR4/MyD88/MAPK signaling pathway. Therefore, THH extract may serve as a microbial modulator to recover RA in clincial practice.ver RA in clincial practice.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

The microbiota-metabolic syndrome axis as a promoter of metabolic osteoarthritis

The relation between obesity and osteoarthritis (OA) development has been traditionally explained as consequence of the excessive joint effort derived of overweight. However, in the last two decades a metabolic OA has been suggested through diverse molecular mechanism implying metabolic syndrome, although more investigation must be conducted to elucidate it. Metabolic syndrome is responsible of the release of diverse inflammatory cytokines, specially the increased adipokine in obesity, causing a chronic low-grade inflammatory status that alters the joint homeostasis. In this scenario, the microbiota dysbiosis contribute by worsening the low-grade chronic inflammation or causing metabolic disorders mediated by endotoxemia generated by an increased lipopolysaccharides intake. This results in joint inflammation and cartilage degradation, which contributes to the development of OA. Also, the insulin resistance provoked by type 2 Diabetes contributes to the OA development. When intake patterns are considered, some coincidences can be pointed between the food patterns associated to the metabolic syndrome and the food patterns associated to OA development. Therefore, these coincidences support the idea of a molecular mechanism of the OA development caused by the molecular mechanism generated under the metabolic syndrome status. This review points the relation between metabolic syndrome and OA, showing the connected molecular mechanisms between both pathologies as well as the shared dietary patterns that promote or prevent both pathologies.

Collagen Hydrolysates: A Source of Bioactive Peptides Derived from Food Sources for the Treatment of Osteoarthritis

Osteoarthritis (OA) is the most common joint disorder, with a social and financial burden that is expected to increase in the coming years. Currently, there are no effective medications to treat it. Due to limited treatment options, patients often resort to supplements, such as collagen hydrolysates (CHs). CHs are products with low molecular weight (MW) peptides, often between 3 and 6 kDa, and are a result of industrialized processed collagen. Collagen extraction is often a by-product of the meat industry, with the main source for collagen-based products being bovine, although it can also be obtained from porcine and piscine sources. CHs have demonstrated positive results in clinical trials related to joint health, such as decreased joint pain, increased mobility, and structural joint improvements. The bioactivity of CHs is primarily attributed to their bioactive peptide (BAP) content. However, there are significant knowledge gaps regarding the digestion, bioavailability, and bioactivity of CH-derived BAPs, and how different CH products compare in that regard. The present review discusses CHs and their BAP content as potential treatments for OA.

N-acetylglucosamine-6-O sulfation on intestinal mucins prevents obesity and intestinal inflammation by regulating gut microbiota

Intestinal mucins play an essential role in the defense against bacterial invasion and the maintenance of gut microbiota, which is instrumental in the regulation of host immune systems; hence, its dysregulation is a hallmark of metabolic disease and intestinal inflammation. However, the mechanism by which intestinal mucins control the gut microbiota as well as disease phenotypes remains nebulous. Herein, we report that N-acetylglucosamine (GlcNAc)-6-O sulfation of O-glycans on intestinal mucins performs a protective role against obesity and intestinal inflammation. Chst4-/- mice, lacking GlcNAc-6-O sulfation of the mucin O-glycans, showed significant weight gain and increased susceptibility to dextran sodium sulfate-induced colitis as well as colitis-associated cancer accompanied by significantly reduced immunoglobulin A (IgA) production caused by an impaired T follicular helper cell-mediated IgA response. Interestingly, the protective effects of GlcNAc-6-O sulfation against obesity and intestinal inflammation depend on the gut microbiota, evidenced by the modulation of the gut microbiota by cohousing or microbiota transplantation reversing disease phenotypes and IgA production. Collectively, our findings provide insight into the significance of host glycosylation, more specifically GlcNAc-6-O sulfation on intestinal mucins, in protecting against obesity and intestinal inflammation via regulation of the gut microbiota.

Possible relationship between the gut leaky syndrome and musculoskeletal injuries: the important role of gut microbiota as indirect modulator

This article aims to examine the evidence on the relationship between gut microbiota (GM), leaky gut syndrome and musculoskeletal injuries. Musculoskeletal injuries can significantly impair athletic performance, overall health, and quality of life. Emerging evidence suggests that the state of the gut microbiota and the functional intestinal permeability may contribute to injury recovery. Since 2007, a growing field of research has supported the idea that GM exerts an essential role maintaining intestinal homeostasis and organic and systemic health. Leaky gut syndrome is an acquired condition where the intestinal permeability is impaired, and different bacteria and/or toxins enter in the bloodstream, thereby promoting systemic endotoxemia and chronic low-grade inflammation. This systemic condition could indirectly contribute to increased local musculoskeletal inflammation and chronificate injuries and pain, thereby reducing recovery-time and limiting sport performance. Different strategies, including a healthy diet and the intake of pre/probiotics, may contribute to improving and/or restoring gut health, thereby modulating both systemically as local inflammation and pain. Here, we sought to identify critical factors and potential strategies that could positively improve gut microbiota and intestinal health, and reduce the risk of musculoskeletal injuries and its recovery-time and pain. In conclusion, recent evidences indicate that improving gut health has indirect consequences on the musculoskeletal tissue homeostasis and recovery through the direct modulation of systemic inflammation, the immune response and the nociceptive pain.

Antibiotic Treatment Prior to Injury Abrogates the Detrimental Effects of LPS in STR/ort Mice Susceptible to Osteoarthritis Development

Post traumatic osteoarthritis (PTOA) is a form of secondary osteoarthritis (OA) that develops in ~50% of cases of severe articular joint injuries and leads to chronic and progressive degradation of articular cartilage and other joint tissues. PTOA progression can be exacerbated by repeated injury and systemic inflammation. Few studies have examined approaches for blunting or slowing down PTOA progression with emphasis on systemic inflammation; most arthritis studies focused on the immune system have been in the context of rheumatoid arthritis. To examine how the gut microbiome affects systemic inflammation during PTOA development, we used a chronic antibiotic treatment regimen starting at weaning for 6 weeks before anterior cruciate ligament (ACL) rupture in STR/ort mice combined with lipopolysaccharide (LPS)-induced systemic inflammation. STR/ort mice develop spontaneous OA as well as a more severe PTOA phenotype than C57Bl/6J mice. By 6 weeks post injury, histological examination showed a more robust cartilage staining in the antibiotic-treated (AB) STR/ort mice than in the untreated STR/ort controls. Furthermore, we also examined the effects of AB treatment on systemic inflammation and found that the effects of LPS administration before injury are also blunted by AB treatment in STR/ort mice. The AB- or AB+LPS-treated STR/ort injured joints more closely resembled the C57Bl/6J VEH OA phenotypes than the vehicle- or LPS-treated STR/ort, suggesting that antibiotic treatment has the potential to slow disease progression and should be further explored therapeutically as prophylactic post injury. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Altered gut microbiota richness in individuals with a history of lateral ankle sprain

This study aimed to examine differences in the intestinal microbiota diversity in individuals with and without a history of a lateral ankle sprain (LAS). Fifty male college student athletes with (n=32) and without (n=18) a LAS history participated in this study. Faecal samples were collected in the morning after awakening during an off-season, and faecal microbiota were characterized via bacteria 16S rRNA amplicon sequencing. Alpha-diversity metrics and ß-diversity indices were calculated to assess the gut microbiota diversity. The LAS-history group significantly had lower Chao1 (p=0.020) and abundance-based coverage estimators (p=0.035) indices compared to the control group. Gut microbiota composition was not significantly different between athletes with a LAS history and controls (R2 =0.01, p 0.414). Athletes with a history of LASs had significantly higher proportions of Bacteroides Fragilis (p=0.024) and Ruminococcus Gnavus (p=0.021) compared with controls. The gut microbiota of athletes with a LAS history had less richness compared to controls, indicating potential associations between a LAS and the gut microbiota. This study highlights the potential link of a LAS to global health. This study may help raise awareness of strategies to prevent long-term health-related negative consequences in people suffering from LASs.

Bifidobacterium longum BORI inhibits pain behavior and chondrocyte death, and attenuates osteoarthritis progression

Osteoarthritis (OA), the most common form of arthritis, is characterized by pain and cartilage damage; it usually exhibits gradual development. However, the pathogenesis of OA remains unclear. This study was undertaken to improve the understanding and treatment of OA. OA was induced in 7-week-old Wistar rats by intra-articular injection of monosodium iodoacetate (MIA); subsequently, the rats underwent oral administration of Bifidobacterium longum BORI (B. BORI). The effects of B. BORI were examined in chondrocytes and an MIA-induced OA rat model. In the rats, B. BORI-mediated effects on pain severity, cartilage destruction, and inflammation were recorded. Additional effects on mRNA and cytokine secretion were analyzed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Paw withdrawal threshold, paw withdrawal latency, and weight-bearing assessments revealed that pain severity in MIA-induced OA rats was decreased after B. BORI treatment. Histopathology analyses and three-dimensional surface renderings of rat femurs from micro-computed tomography images revealed cartilage protection and cartilage loss inhibition effects in B. BORI-treated OA rats. Immunohistochemical analyses of inflammatory cytokines and catabolic markers (e.g., matrix metalloproteinases) showed that the expression levels of both were reduced in tissue from B. BORI-treated OA rats. Furthermore, B. BORI treatment decreased the expression levels of the inflammatory cytokine monocyte chemoattractant protein-1 and inflammatory gene factors (e.g., inflammatory cell death markers) in chondrocytes. The findings indicate that oral administration of B. BORI has therapeutic potential in terms of reducing pain, progression, and inflammation in OA.

The immune role of the intestinal microbiome in knee osteoarthritis: a review of the possible mechanisms and therapies

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage damage and synovial inflammation and carries an enormous public health and economic burden. It is crucial to uncover the potential mechanisms of OA pathogenesis to develop new targets for OA treatment. In recent years, the pathogenic role of the gut microbiota in OA has been well recognized. Gut microbiota dysbiosis can break host-gut microbe equilibrium, trigger host immune responses and activate the "gut-joint axis", which aggravates OA. However, although the role of the gut microbiota in OA is well known, the mechanisms modulating the interactions between the gut microbiota and host immunity remain unclear. This review summarizes research on the gut microbiota and the involved immune cells in OA and interprets the potential mechanisms for the interactions between the gut microbiota and host immune responses from four aspects: gut barrier, innate immunity, adaptive immunity and gut microbiota modulation. Future research should focus on the specific pathogen or the specific changes in the gut microbiota composition to identify the related signaling pathways involved in the pathogenesis of OA. In addition, future studies should include more novel interventions on immune cell modifications and gene regulation of specific gut microbiota related to OA to validate the application of gut microbiota modulation in the onset of OA.

Targeting the Inflammatory Hallmarks of Obesity-Associated Osteoarthritis: Towards Nutraceutical-Oriented Preventive and Complementary Therapeutic Strategies Based on n-3 Polyunsaturated Fatty Acids

Obesity (Ob), which has dramatically increased in the last decade, is one of the main risk factors that contribute to the incidence and progression of osteoarthritis (OA). Targeting the characteristics of obesity-associated osteoarthritis (ObOA) may offer new chances for precision medicine strategies in this patient cohort. First, this review outlines how the medical perspective of ObOA has shifted from a focus on biomechanics to the significant contribution of inflammation, mainly mediated by changes in the adipose tissue metabolism through the release of adipokines and the modification of fatty acid (FA) compositions in joint tissues. Preclinical and clinical studies on n-3 polyunsaturated FAs (PUFAs) are critically reviewed to outline the strengths and weaknesses of n-3 PUFAs' role in alleviating inflammatory, catabolic and painful processes. Emphasis is placed on potential preventive and therapeutic nutritional strategies based on n-3 PUFAs, with a focus on ObOA patients who could specifically benefit from reformulating the dietary composition of FAs towards a protective phenotype. Finally, tissue engineering approaches that involve the delivery of n-3 PUFAs directly into the joint are explored to address the perspectives and current limitations, such as safety and stability issues, for implementing preventive and therapeutic strategies based on dietary compounds in ObOA patients.

Effect of green-lipped mussel (Perna canaliculus) supplementation on faecal microbiota, body composition and iron status markers in overweight and obese postmenopausal women: a randomised, double-blind, placebo-controlled trial

The present study aimed to determine the effect of whole meat GSM powder on gut microbiota abundance, body composition and iron status markers in healthy overweight or obese postmenopausal women. This was a 3-months trial involving forty-nine healthy postmenopausal women with body mass index (BMI) between 25 and 35 kg/m2 who were randomly assigned to receive 3 g/d of either GSM powder (n 25) or placebo (n 24). The gut microbe abundance, serum iron status markers and body composition were measured at the baseline and the end of the study. The between-group comparison at the baseline showed a lower abundance of Bacteroides and Clostridium XIVa in the GSM group compared with the placebo (P = 0⋅04). At the baseline, the body fat (BF)% and gynoid fat% were higher in the GSM group compared with the placebo (P < 0⋅05). No significant changes were found in any of the outcome measures, except for ferritin levels that showed a significant reduction over time (time effect P = 0⋅01). Some trend was observed in bacteria including Bacteroides and Bifidobacterium which tended to increase in the GSM group while their abundance decreased or remained at their baseline level in the control group. Supplementation with GSM powder did not result in any significant changes in gut microbe abundance, body composition and iron markers compared with placebo. However, some commensal bacteria such as Bacteroides and Bifidobacteria tended to increase following supplementation with GSM powder. Overall, these findings can expand the knowledge surrounding the effects of whole GSM powder on these outcome measures in healthy postmenopausal women.

Free lipoproteins from Bifidobacterium longum alleviate osteoarthritis through modulation of the gut microbiome

Aim: The "gut-joint" axis is suspected to be involved in the pathophysiology of osteoarthritis (OA). The present study aims at investigating the potential of lipoproteins (Lpps) secreted by Bifidobacterium longum to alleviate OA progression in the rat. Methods: Experimental OA was induced in rats harbouring Schaedler Flora maintained in SPF conditions. Two weeks post-injection, 20 rats were randomized to water (n = 10) or 0.3 mg/L Lpps solution (n = 10). Weight and food intake were monitored for 6 weeks. At sacrifice, joints were scored using macroscopic and histological criteria. Serum LPS, Schaedler flora as well as selected intestinal bacteria were analyzed. Results: Lpps intake prevents OA progression. The protected rats showed a significant increase in lactobacilli along the intestine as well as in Mucispirillum schaedleri in the colon and a significant decrease in Parabacteroides goldsteini and Akkermansia in caecum and colon, respectively. There was no significant difference in serum lipopolysaccharide or bacteria translocating in Peyer's patches. Labelled Lpps were not detected in bone marrow of the OA joint. The principal component analysis points out that OA prevention is primarily associated with bacteria involved in the tryptophane degradation pathway and SCFA formation. Conclusion: In rats deprived of bifidobacteria, intake of B.longum Lpps prevented OA development and modulated the intestinal microbiome with a possible impact on the bacterial end-products. The link between Lpps and the gut microbial metabolome warrants further investigation.

"Cross-talk" between gut microbiome dysbiosis and osteoarthritis progression: a systematic review

Objectives

The aim of this systematic review was to summarize the available literature on gut microbiome (GMB) and osteoarthritis (OA), analyze the correlation between GMB and OA, and explore potential underlying mechanisms.

Methods

A systematic search of the PubMed, Embase, Cochrane, and Web of Science with the keywords "Gut Microbiome" and "Osteoarthritis" was conducted to identify the human and animal studies exploring the association between GMB and OA. The retrieval time range was from the database inception to July 31, 2022. Studies reported the other arthritic diseases without OA, reviews, and studies focused on the microbiome in other parts of the body with OA, such as oral or skin, were excluded. The included studies were mainly reviewed for GMB composition, OA severity, inflammatory factors, and intestinal permeability.

Results

There were 31 studies published met the inclusion criteria and were analyzed, including 10 human studies and 21 animal studies. Human and animal studies have reached a consistent conclusion that GMB dysbiosis could aggravate OA. In addition, several studies have found that alterations of GMB composition can increase intestinal permeability and serum levels of inflammatory factors, while regulating GMB can alleviate the changes. Owing to the susceptibility of GMB to internal and external environments, genetics, and geography, the included studies were not consistent in GMB composition analysis.

Conclusion

There is a lack of high-quality studies evaluating the effects of GMB on OA. Available evidence indicated that GMB dysbiosis aggravated OA through activating the immune response and subsequent induction of inflammation. Future studies should focus on more prospective, cohort studies combined with multi-omics to further clarify the correlation.

Synovial joint-on-a-chip for modeling arthritis: progress, pitfalls, and potential

Disorders of the synovial joint, such as osteoarthritis (OA) and rheumatoid arthritis (RA), afflict a substantial proportion of the global population. However, current clinical management has not been focused on fully restoring the native function of joints. Organ-on-chip (OoC), also called a microphysiological system, which typically accommodates multiple human cell-derived tissues/organs under physiological culture conditions, is an emerging platform that potentially overcomes the limitations of current models in developing therapeutics. Herein, we review major steps in the generation of OoCs for studying arthritis, discuss the challenges faced when these novel platforms enter the next phase of development and application, and present the potential for OoC technology to investigate the pathogenesis of joint diseases and the development of efficacious therapies.

Tamarind Xyloglucan Oligosaccharides Attenuate Metabolic Disorders via the Gut-Liver Axis in Mice with High-Fat-Diet-Induced Obesity

Functional oligosaccharides exert obesity-reducing effects by acting at various pathological sites responsible for the development of obesity. In this study, tamarind xyloglucan oligosaccharides (TXOS) were used to attenuate metabolic disorders via the gut-liver axis in mice with high-fat-diet (HFD)-induced obesity, as determined through LC/MS-MS and 16S rRNA sequencing technology. A TXOS dose equivalent to 0.39 g/kg/day in humans restored the gut microbiota in obese mice, which was in part supported by the key microflora, particularly Bifidobacterium pseudolongum. Moreover, TXOS reduced the abundance of opportunistic pathogen species, such as Klebsiella variicola and Romboutsia ilealis. The bodyweight and weight gain of TXOS-treated (4.8 g/kg per day) mice began to decrease at the 14th week, decreasing by 12.8% and 23.3%, respectively. Sixteen fatty acids were identified as potential biomarkers in the liver, and B. pseudolongum and caprylic acid were found to tightly regulate each other. This was associated with reduced inflammation in the liver, circulation, and adipose tissue and protection from metabolic disorders. The findings of this study indicate that TXOS can significantly increase the gut microbiota diversity of obese mice and restore the HFD-induced dysbiosis of gut microbiota.

The intervention effects of konjac glucomannan with different molecular weights on high-fat and high-fructose diet-fed obese mice based on the regulation of gut microbiota

Konjac is a high-quality dietary fiber rich in β-glucomannan, which has been reported to possess anti-obesity effects. To explore the effective components and the structure-activity relationships of konjac glucomannan (KGM), three different molecular weight components (KGM-1 (90 kDa), KGM-2 (5 kDa), KGM-3 (1 kDa)) were obtained, and systematical comparisons of their effects on high-fat and high-fructose diet (HFFD)-induced obese mice were investigated in the present study. Our results indicated that KGM-1, with its larger molecular weight, reduced mouse body weight and improved their insulin resistance status. KGM-1 markedly inhibited lipid accumulation in mouse livers induced by HFFD by downregulating Pparg expression and upregulating Hsl and Cpt1 expressions. Further investigation revealed that dietary supplementation with konjac glucomannan at different molecular weights caused β-diversity changes in gut microbes. The potential weight loss effect of KGM-1 maybe attributed to the abundance of changes in Coprobacter, Streptococcus, Clostridium IV, and Parasutterella. The results provide a scientific basis for the in-depth development and utilization of konjac resources.

Gut microbiome-based strategies for host health and disease

Host health and disease are influenced by changes in the abundance and structure of intestinal flora. Current strategies are focused on regulating the structure of intestinal flora to ensure host health by alleviating disease. However, these strategies are limited by multiple factors, such as host genotype, physiology (microbiome, immunity, and gender), intervention, and diet. Accordingly, we reviewed the prospects and limitations of all strategies regulating the structure and abundance of microflora, including probiotics, prebiotics, diet, fecal microbiota transplantation, antibiotics, and phages. Some new technologies that can improve these strategies are also introduced. Compared with other strategies, diets and prebiotics are associated with reduced risk and high security. Besides, phages have the potential for application in the targeted regulation of intestinal microbiota due to their high specificity. Notably, the variability in individual microflora and their metabolic response to different interventions should be considered. Future studies should use artificial intelligence combined with multi-omics to investigate the host genome and physiology based on factors, such as blood type, dietary habits, and exercise, in order to develop individualized intervention strategies to improve host health.