High-fat/high-sucrose diet-induced obesity results in joint-specific development of osteoarthritis-like degeneration in a rat model

The application of human medical image-based finite element analysis in the construction of mouse osteoarthritis models

The anterior cruciate ligament plays an important role in maintaining the stability of the knee joint. Its injury is a common cause of articular cartilage degeneration and osteoarthritis (OA). The anterior cruciate ligament transection (ACLT) method is commonly employed to construct animal models for studying osteoarthritis pathogenesis. However, the precise mechanism of how anterior cruciate ligament injury leads to osteoarthritis is not fully understood. This study utilized finite element analysis (FEA) with human medical images to simulate the biomechanical characteristics of anterior cruciate ligament (ACL) injury. Osteoarthritis models were subsequently established in C57BL/6 mice using ACLT to explore the link between ACL injury and osteoarthritis development. The results of FEA showed that, after an anterior cruciate ligament injury, abnormal stress was concentrated in the medial and lateral of the femoral and tibial articular cartilage during knee flexion and extension. In order to better display the pathological changes of articular cartilage in the stress areas, the medial tibial cartilage was selected as a representative area to observe the continuous pathological changes of articular cartilage in ACLT-induced OA mice. The articular cartilage degeneration was most dramatic at four weeks post ACLT operation and then remained relatively stable. This study may have significant implications for the development of animal models of osteoarthritis and provide a reference for histopathological research on osteoarthritis.

Effects of risk factors on evoked pain patterns in rat models of experimental knee osteoarthritis

Pain experiences in patients with knee osteoarthritis (OA) may be influenced differently by OA risk factors, reducing the translatability of preclinical research into the clinic. Our objective was to contrast evoked pain patterns after exposure to different OA risk factors including acute joint trauma, chronic instability, or obesity/metabolic syndrome using rat models of experimental knee OA. We tested longitudinal patterns of evoked pain behaviors (knee pressure pain threshold and hindpaw withdrawal threshold) in young male rats exposed to different OA-inducing risk factors including (1) nonsurgical joint trauma (impact-induced anterior cruciate ligament (ACL) rupture); (2) surgical joint destabilization (ACL + medial meniscotibial ligament transection); and (3) high fat/sucrose (HFS) diet-induced obesity. Histopathology for synovitis, cartilage damage, and subchondral bone morphology was performed. Pressure pain threshold was reduced (more pain) most, and earlier by joint trauma (Week 4-12) and HFS (Week 8-28) than by joint destabilization (Week 12). Hindpaw withdrawal threshold was reduced transiently after joint trauma (Week 4), with smaller and later reductions after joint destabilization (Week 12), but not with HFS. Synovial inflammation occurred at Week 4 after joint trauma and instability but only coincided with pain behaviors after joint trauma. Cartilage and bone histopathology were most severe after joint destabilization and least severe with HFS. The pattern, intensity, and timing of evoked pain behaviors varied due to OA risk factor exposure and were inconsistently associated with histopathological OA features. These findings may help to explain the challenges with translating preclinical OA pain research to multimorbid clinical OA contexts.

High-fat diet aggravates the severity of the in vitro posttraumatic osteoarthritis model through macrophagic FBW7

Osteoarthritis (OA) is a prevalent and distressing chronic degenerative joint disorder characterized by damaged articular cartilage and inflamed joints. Among risk factors, obesity has emerged as the second-leading contributor to OA after age. Obesity is believed to play a key role in the development and progression of OA. This study aimed to investigate the role and underlying mechanisms of high-fat diet (HFD)-induced obesity in the development of OA. Our findings revealed that HFD could aggravate the destabilization of the medial meniscus (DMM)-induced damage in the mouse model of obesity. Similar results were observed when macrophages obtained from HFD-fed mice were cocultured with cartilage and subsequently stimulated with interleukin-1β (IL-1β). Mechanistically, we observed a decrease in the expression of intraarticular macrophagic FBW7, which was implicated in the aggravation of OA in the HFD-fed animal. Furthermore, by modulating the immune status of macrophages, we found that reversing the macrophagic expression of FBW7 in these cells can alleviate the chondrocyte damage. In conclusion, this study provides novel insights into the pathological mechanisms underlying HFD-related OA development by identifying the role of FBW7 in synovial macrophages. These findings open up new avenues for research and therapeutic interventions targeting HFD-related OA.

Aerobic and Resistance Training Attenuate Differently Knee Joint Damage Caused by a High-Fat-High-Sucrose Diet in a Rat Model

OBJECTIVE

Obesity and associated low-level local systemic inflammation have been linked to an increased rate of developing knee osteoarthritis (OA). Aerobic exercise has been shown to protect the knee from obesity-induced joint damage. The aims of this study were to determine (1) if resistance training provides beneficial metabolic effects similar to those previously observed with aerobic training in rats consuming a high-fat/high-sucrose (HFS) diet and (2) if these metabolic effects mitigate knee OA in a diet-induced obesity model in rats.

DESIGN

Twelve-week-old Sprague-Dawley rats were randomized into 4 groups: (1) a group fed an HFS diet subjected to aerobic exercise (HFS+Aer), (2) a group fed an HFS diet subjected to resistance exercise (HFS+Res), (3) a group fed an HFS diet with no exercise (HFS+Sed), and (4) a chow-fed sedentary control group (Chow+Sed). HFS+Sed animals were heavier and had greater body fat, higher levels of triglycerides and total cholesterol, and more joint damage than Chow+Sed animals.

RESULTS

The HFS+Res group had higher body mass and body fat than Chow+Sed animals and higher OA scores than animals from the HFS+Aer group. Severe bone lesions were observed in the HFS+Sed and Chow+Sed animals at age 24 weeks, but not in the HFS+Res and HFS+Aer group animals.

CONCLOSION

In summary, aerobic training provided better protection against knee joint OA than resistance training in this rat model of HFS-diet-induced obesity. Exposing rats to exercise, either aerobic or resistance training, had a protective effect against the severe bone lesions observed in the nonexercised rats.

Effects of different obesogenic diets on joint integrity, inflammation and intermediate monocyte levels in a rat groove model of osteoarthritis

Introduction: Obesogenic diets aggravate osteoarthritis (OA) by inducing low-grade systemic inflammation, and diet composition may affect OA severity. Here, we investigated the effect of diet on joint damage and inflammation in an OA rat model. Methods: Wistar-Han rats (n = 24) were fed a chow, a high-fat (HF) diet, or a high-fat/high-sucrose (HFS) for 24 weeks. OA was induced unilaterally 12 weeks after the diet onset by groove surgery, and compared to sham surgery or no surgical intervention (contralateral limb). Knee OA severity was determined by OARSI histopathology scoring system. At several timepoints monocyte populations were measured using flow cytometry, and joint macrophage response was determined via CD68 immunohistochemistry staining. Results: Groove surgery combined with HF or HFS diet resulted in higher OARSI scores, and both HF and HFS diet showed increased circulating intermediate monocytes compared to chow fed rats. Additionally, in the HFS group, minimal damage by sham surgery resulted in an increased OARSI score. HFS diet resulted in the largest metabolic dysregulation, synovial inflammation and increased CD68 staining in tibia epiphysis bone marrow. Conclusion: Obesogenic diets resulted in aggravated OA development, even with very minimal joint damage when combined with the sucrose/fat-rich diet. We hypothesize that diet-induced low-grade inflammation primes monocytes and macrophages in the blood, bone marrow, and synovium, resulting in joint damage when triggered by groove OA inducing surgery. When the metabolic dysregulation is larger, as observed here for the HFS diet, the surgical trigger required to induce joint damage may be smaller, or even redundant.

The role of PIEZO ion channels in the musculoskeletal system

PIEZO1 and PIEZO2 are mechanosensitive cation channels that are highly expressed in numerous tissues throughout the body and exhibit diverse, cell-specific functions in multiple organ systems. Within the musculoskeletal system, PIEZO1 functions to maintain muscle and bone mass, sense tendon stretch, and regulate senescence and apoptosis in response to mechanical stimuli within cartilage and the intervertebral disc. PIEZO2 is essential for transducing pain and touch sensations as well as proprioception in the nervous system, which can affect musculoskeletal health. PIEZO1 and PIEZO2 have been shown to act both independently as well as synergistically in different cell types. Conditions that alter PIEZO channel mechanosensitivity, such as inflammation or genetic mutations, can have drastic effects on these functions. For this reason, therapeutic approaches for PIEZO-related disease focus on altering PIEZO1 and/or PIEZO2 activity in a controlled manner, either through inhibition with small molecules, or through dietary control and supplementation to maintain a healthy cell membrane composition. Although many opportunities to better understand PIEZO1 and PIEZO2 remain, the studies summarized in this review highlight how crucial PIEZO channels are to musculoskeletal health and point to promising possible avenues for their modulation as a therapeutic target.

Factors associated with subjective knee joint stiffness in people with knee osteoarthritis: A systematic review

INTRODUCTION

Subjective knee stiffness is a common symptom in patients with knee osteoarthritis treated conservatively. However, the influencing factors or effects of knee joint stiffness are unknown. The aim of this study was to explore the factors associated with subjective knee stiffness in patients with knee osteoarthritis.

METHODS

The MEDLINE, Cochrane Central Register of Controlled Trials, EMBASE, Cumulative Index to Nursing and Allied Health Literature, Web of Science, and PEDro databases were searched in November 2021. Prospective or retrospective cohort studies were included. The methodological quality of the selected articles was assessed using the Scottish Intercollegiate Guidelines Network checklist.

RESULTS

Twenty out of 1943 screened articles were included in this systematic review. Eighteen and two studies were rated as having acceptable and low quality, respectively. All the included studies measured subjective knee stiffness using the Western Ontario and McMaster Universities Osteoarthritis Index. The main findings were that worse preoperative subjective knee stiffness was associated with worse pain, subjective knee stiffness, and patient satisfaction at 1 year after total knee arthroplasty. In addition, worse subjective knee stiffness was associated with future degenerative changes in the knee joint, such as joint space narrowing and osteophyte growth progression.

CONCLUSION

Subjective knee stiffness may be associated with the prognosis after total knee arthroplasty and degenerative changes in the knee joint. Early detection and treatment of knee stiffness could lead to a good prognosis after total knee arthroplasty and prevent the progression of degenerative changes in the knee joint.

Excessive sucrose exacerbates high fat diet-induced hepatic inflammation and fibrosis promoting osteoarthritis in mice model

Osteoarthritis (OA) is marked by chronic low-grade systemic inflammation and cartilage destruction. High fat diet causes obesity and increases the risk of knee OA-development. However, the impact of high dietary sugar intake on OA pathogenesis has not been elucidated yet. Therefore, we investigated the effects of a high-fat and high-sucrose (HF+HS) diet in experimental OA mouse models. Eight-week-old male C57BL/6J mice were fed a standard chow (n=6), high-fat (HF) (n=5), or HF+HS (n=7) diets for 12 weeks; thereafter, the mice underwent surgical destabilization of the medial meniscus (DMM) and received the same experimental diets for an additional 8 weeks. The pathogenesis of knee OA, obesogenic parameters, and inflammation levels in the liver and adipose tissue were investigated. HF+HS diet induced severe cartilage erosion with osteophyte development and subchondral bone plate thickening, indicating that HF+HS diet exacerbated OA. Despite marginal differences in metabolic parameters, hepatic free cholesterol accumulation increased in mice with DMM-induced OA fed on HF+HS diet than in those fed HF diet. Notably, the levels of inflammatory cytokines and fibrosis markers were greater in the livers of mice with DMM-induced OA, fed on HF+HS diet than those in the control group. However, adipose tissue remodeling was not affected by the HF+HS diet. These findings indicate that excess sucrose intake along with a HF diet triggers hepatic inflammation and fibrosis, thereby, contributing to OA pathogenesis.

Osteoarthritis as an Umbrella Term for Different Subsets of Humans Undergoing Joint Degeneration: The Need to Address the Differences to Develop Effective Conservative Treatments and Prevention Strategies

Osteoarthritis (OA) of joints such as the knee and hip are very prevalent, and the number of individuals affected is expected to continue to rise. Currently, conservative treatments after OA diagnosis consist of a series of increasingly invasive interventions as the degeneration and pain increase, leading very often to joint replacement surgery. Most interventions are focused on alleviating pain, and there are no interventions currently available that stop and reverse OA-associated joint damage. For many decades OA was considered a disease of cartilage, but it is now considered a disease of the whole multi-tissue joint. As pain is the usual presenting symptom, for most patients, it is not known when the disease process was initiated and what the basis was for the initiation. The exception is post-traumatic OA which results from an overt injury to the joint that elevates the risk for OA development. This scenario leads to very long wait lists for joint replacement surgery in many jurisdictions. One aspect of why progress has been so slow in addressing the needs of patients is that OA has been used as an umbrella term that does not recognize that joint degeneration may arise from a variety of mechanistic causes that likely need separate analysis to identify interventions unique to each subtype (post-traumatic, metabolic, post-menopausal, growth and maturation associated). A second aspect of the slow pace of progress is that the bulk of research in the area is focused on post-traumatic OA (PTOA) in preclinical models that likely are not clearly relevant to human OA. That is, only ~12% of human OA is due to PTOA, but the bulk of studies investigate PTOA in rodents. Thus, much of the research community is failing the patient population affected by OA. A third aspect is that conservative treatment platforms are not specific to each OA subset, nor are they integrated into a coherent fashion for most patients. This review will discuss the literature relevant to the issues mentioned above and propose some of the directions that will be required going forward to enhance the impact of the research enterprise to affect patient outcomes.

Probiotic Therapy with Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis Results in Infarct Size Limitation in Rats with Obesity and Chemically Induced Colitis

In this study, we investigated the effect of three different probiotics, namely, a combination of Lactobacillus acidophilus (LA-5) and Bifidobacterium animalis subsp. lactis (BB-12), Saccharomyces boulardii, and Enterococcus faecium L3 on myocardial infarct size in rats with diet-induced obesity (DIO) and chemically-induced colitis (CIC). Potential associations between the effects of probiotics on myocardial ischemia-reperfusion injury and gut microbiome patterns as well as the serum levels of pro- and anti-inflammatory cytokines, lipopolysaccharide, and short chain fatty acids were also studied. Intragastric administration of lyophilized Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis at a dose of 1.2 × 108 CFU/mL for 15 days resulted in myocardial infarct size reduction in rats with DIO, CIC, and antibiotic-induced dysbiosis. This cardioprotective effect was associated with specific changes in cytokine concentrations, namely reduced levels of IL-1β, TNF-α, IL-2, and IL-8. At the same time, the use of Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis was accompanied by a significant reduction in lipopolysaccharide level, suggesting normalization of intestinal epithelial barrier permeability. However, the cardioprotective effect of Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis is not secondary to improved healing of the intestinal mucosa in CIC, as evidenced by the lack of difference in histopathological scores.

Effect of short-term high fat diet on resistin levels and expression of autophagy-related genes in the cartilage of male rats

Obesity is a significant risk factor for the development of knee osteoarthritis (KOA). However, the precise molecular mechanisms linking obesity to OA remain unclear. In the present study, we investigated the effect of short-term high-fat diet (HFD) on the development of OA and the possible role of the adipokine resistin and autophagy-related genes in mediating this effect. Thirty adult male Wistar rats were equally divided into 2 groups: control and obese groups. Body mass index (BMI), levels of lipid profile, glucose, insulin and HOMA-IR index were significantly higher in the obese group compared with control. Our results revealed significantly higher serum and cartilage resistin levels with a significant increase in the mRNA expressions of toll-like receptor 4 (TLR4), matrix metalloproteinase-9 (MMP-9) and interleukin-1β (IL-1β) as well as protein levels of IL-1β, matrix metalloproteinase-13 (MMP-13), ADAMTS 5 (aggrecanase-2) and caspase-3 in the cartilage of obese rats. The HFD induced a significant upregulation of autophagy related 5 (ATG5), beclin-1 and light chain 3 (LC3) mRNA expressions and a significant downregulation of mammalian target of rapamycin (mTOR) expression in cartilage. The protein levels of cartilage ATG5 were also significantly elevated in HFD-fed group. In conclusion, we suggested that increased levels of resistin and expression of autophagy-related genes may contribute in part, to OA development in HFD-fed rats. This provides a novel insight into the early molecular changes in the cartilage associated with obesity.

Effect of a maternal high fat diet with vegetable substitution on fetal brain transcriptome

Maternal dietary conditions play a major role in fetal growth and brain development. The primary aim of this study was to determine the effects of 5% of energy substitution by vegetables in a maternal dietary fat on placental and fetal weight and on fetal brain gene expression. Two-month-old female C57BL/6 mice were fed 16% (normal-fat, NF), 45% fat (HF), or HF substituted with vegetables (5% energy, HF+VS) diets for 12 weeks. Dams were then bred with NF diet-fed male mice. Placenta and fetal weights were measured at gestational age 19 (D19). RNA was isolated from fetal whole brains and sequenced using Illumina HiSeq. HF+VS diet prevented maternal HF diet-induced decreases in placental weight at D19. Feeding of a maternal HF diet was associated with 79 differentially expressed genes (DEGs), while maternal vegetable substitution was associated with 131 DEGs. The vegetable substitution diet decreased Apold1 (P=0.0319), Spata2l (P=0.0404) and Celsr1 (P<0.03) expression compared to HF diet. Enrichment analysis of HF vs HF +VS DEGs identified that synapse organization, and regulation of embryonic development were significantly represented. KEGG enrichment analysis identified a significant representation of DEGs in the ubiquitin mediated proteolysis pathway in HF vs HF +VS, and chemokine signaling pathway in NF vs HF. These findings suggest that at D19, in a rodent model, a maternal HF diet alters placental and fetal growth, and that vegetable supplementation renders a protective effect against these changes.

The repair effect and mechanism of continuous passive motion on osteoarthritis in a rabbit model

OBJECTIVE

To observe the effect of continuous passive motion (CPM) on osteoarthritis in a rabbit model and explore its mechanism.

METHODS

Thirty healthy rabbits with a total of 60 knee joints were randomized into three groups. Group A had CPM for 8 h daily, starting on postoperative day 1 and free movement in the cage, group B received CPM for 2 h daily, starting on postoperative day 1 and free movement in the cage, and group C only had free movement in the cage. Mankin's score was used to compare the gross morphology of the rabbit's knee joint. Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured by RT-PCR and western blot method before and after intervention.

RESULTS

The Mankin's scores of rabbits in groups A and B were significantly lower than those in group C, and those in group A were lower than those in group B at week 4 and week 12 of intervention (P<0.05). At week 4 of the CPM intervention, the gross morphological scores were the highest in group A, followed by group B, and the lowest in group C (P<0.05). At week 12 of CPM intervention, the gross morphological scores of the knee joints in groups A and B were increased again, which were the highest in group A, followed by group B, and the lowest in group C (P<0.05). At week 12 of intervention, MDA levels in group A were lower than those in groups B and C, whereas SOD levels in group A were higher than those in groups B and C.

CONCLUSION

CPM can effectively improve the symptoms of knee osteoarthritis in rabbits and increase the mobility of the joints, and the mechanism may be related to the ability of CPM to reduce the overproduction of peroxide at the lesion site.

OA foundations - experimental models of osteoarthritis

Osteoarthritis (OA) is increasingly recognised as a disease of diverse phenotypes with variable clinical presentation, progression, and response to therapeutic intervention. This same diversity is readily apparent in the many animal models of OA. However, model selection, study design, and interpretation of resultant findings, are not routinely done in the context of the target human (or veterinary) patient OA sub-population or phenotype. This review discusses the selection and use of animal models of OA in discovery and therapeutic-development research. Beyond evaluation of the different animal models on offer, this review suggests focussing the approach to OA-animal model selection on study objective(s), alignment of available models with OA-patient sub-types, and the resources available to achieve valid and translatable results. How this approach impacts model selection is discussed and an experimental design checklist for selecting the optimal model(s) is proposed. This approach should act as a guide to new researchers and a reminder to those already in the field, as to issues that need to be considered before embarking on in vivo pre-clinical research. The ultimate purpose of using an OA animal model is to provide the best possible evidence if, how, when and where a molecule, pathway, cell or process is important in clinical disease. By definition this requires both model and study outcomes to align with and be predictive of outcomes in patients. Keeping this at the forefront of research using pre-clinical OA models, will go a long way to improving the quality of evidence and its translational value.

Contractility of permeabilized rat vastus intermedius muscle fibres following high-fat, high-sucrose diet consumption

Obesity is a worldwide health concern associated with impaired physical function. It is not clear if contractile protein dysfunction contributes to the impairment of muscle function observed with obesity. The purpose of this study was to examine if diet-induced obesity affects contractile function of chemically permeabilized vastus intermedius fibres of male Sprague-Dawley rats expressing fast myosin heavy chain (MHC) IIa or slow MHC I. Rats consumed either a high-fat, high sucrose (HFHS) diet or a standard (CHOW) diet beginning as either weanlings (7-week duration: WEAN7 cohort, or 14-week duration: WEAN14 cohort) or young adults (12-week duration: ADULT12 cohort, 24-week duration: ADULT24 cohort). HFHS-fed rats had higher (P < 0.05) whole-body adiposity (derived from dual-energy X-ray absorptiometry) than CHOW-fed rats in all cohorts. Relative to CHOW diet groups, the HFHS diet was associated with impaired force production in (a) MHC I fibres in the ADULT24 cohort; and (b) MHC IIa fibres in the ADULT12 and ADULT24 cohorts combined. However, the HFHS diet did not significantly affect the Ca2+-sensitivity of force production, unloaded shortening velocity, or ratio of active force to active stiffness in any cohort. We conclude that diet-induced obesity can impair force output of permeabilized muscle fibres of adult rats. Novelty: We assessed contractile function of permeabilized skeletal muscle fibres in a rat model of diet-induced obesity. The high-fat, high-sucrose diet was associated with impaired force output of fibres expressing MHC I or MHC IIa in some cohorts of rats. Other measures of contractile function were not significantly affected by diet.

Moderate aerobic exercise, but not dietary prebiotic fibre, attenuates losses to mechanical property integrity of tail tendons in a rat model of diet-induced obesity

The purpose of this study was to investigate the alterations with obesity, and the effects of moderate aerobic exercise or prebiotic dietary-fibre supplementation on the mechanical and biochemical properties of the tail tendon in a rat model of high-fat/high-sucrose (HFS) diet-induced obesity. Thirty-two male Sprague-Dawley rats were randomized to chow (n = 8) or HFS (n = 24) diets. After 12-weeks, the HFS fed rats were further randomized into sedentary (HFS sedentary, n = 8), exercise (HFS + E, n = 8) or prebiotic fibre supplementation (HFS + F, n = 8) groups. After another 12-weeks, rats were sacrificed, and one tail tendon was isolated and tested. Stress-relaxation and stretch-to-failure tests were performed to determine mechanical properties (peak, steady-state, yield and failure stresses, Young's modulus, and yield and failure strains) of the tendons. The hydroxyproline content was also analyzed. The HFS sedentary and HFS + F groups had higher final body masses and fat percentages compared to the chow and HFS + E groups. Yield strain was reduced in the HFS sedentary rats compared to the chow rats. Peak and steady-state stresses, failure strain, Young's modulus, and hydroxyproline content were not different across groups. Although the HFS + E group showed higher failure stress, yield stress, and yield strain compared to the HFS sedentary group, HFS + F animals did not produce differences in the properties of the tail tendon compared to the HFS sedentary group. These results indicate that exposure to a HFS diet led to a reduction in the yield strain of the tail tendon and aerobic exercise, but not fibre supplementation, attenuated these diet-related alterations to tendon integrity.

Effects of Herring Milt Hydrolysates and Fractions in a Diet-Induced Obesity Model

Over the past years, promising results from studies have shown that herring milt hydrolysates (HMH) can counter immune-metabolic disorders associated with obesity. However, more studies must corroborate these results. Thus, three commercial hydrolysates (HMH1, HMH2, and HMH3) as well as the fractions of two of them (HMH4 and HMH5) obtained by electrodialysis with ultrafiltration membranes (EDUF) were evaluated in vivo at higher doses compared to a previous study. To achieve this, seven groups of mice were fed for 8 weeks with either a control Chow diet or an obesogenic diet rich in fat and sucrose (HFHS) and supplemented by daily gavage with water or 312.5 mg/kg of one of the five HMH products. In summary, HMH supplements had no impact on weight gain. In the insulin tolerance test (ITT), HMH2 and its HMH5 fraction significantly reduced the blood sugar variation (p < 0.05). However, during the glucose tolerance (OGTT), HMH2 supplement increased the hyperinsulinemia variation (p < 0.05) induced by the HFHS diet. HMH1, HMH2, and HMH5 supplements generated potentially beneficial changes for health in the gut microbiota. These results reveal that HMH do not counteract obesity effects but may decrease certain physiological effects induced by obesity.

MicroRNA-183 attenuates osteoarthritic pain by inhibiting the TGFα-mediated CCL2/CCR2 signalling axis

AIMS

MicroRNA-183 (miR-183) is known to play important roles in osteoarthritis (OA) pain. The aims of this study were to explore the specific functions of miR-183 in OA pain and to investigate the underlying mechanisms.

METHODS

Clinical samples were collected from patients with OA, and a mouse model of OA pain was constructed by surgically induced destabilization of the medial meniscus (DMM). Reverse transcription quantitative polymerase chain reaction was employed to measure the expression of miR-183, transforming growth factor α (TGFα), C-C motif chemokine ligand 2 (CCL2), proinflammatory cytokines (interleukin (IL)-6, IL-1β, and tumour necrosis factor-α (TNF-α)), and pain-related factors (transient receptor potential vanilloid subtype-1 (TRPV1), voltage-gated sodium 1.3, 1.7, and 1.8 (Nav1.3, Nav1.7, and Nav1.8)). Expression of miR-183 in the dorsal root ganglia (DRG) of mice was evaluated by in situ hybridization. TGFα, CCL2, and C-C chemokine receptor type 2 (CCR2) levels were examined by immunoblot analysis and interaction between miR-183 and TGFα, determined by luciferase reporter assay. The extent of pain in mice was measured using a behavioural assay, and OA severity assessed by Safranin O and Fast Green staining. Immunofluorescent staining was conducted to examine the infiltration of macrophages in mouse DRG.

RESULTS

miR-183 was downregulated in tissue samples from patients and mice with OA. In DMM mice, overexpression of miR-183 inhibited the expression of proinflammatory cytokines (IL-6, IL-1β, TNF-α) and pain-related factors (TRPV1, Nav1.3, Nav1.7, Nav1.8) in DRG. OA pain was relieved by miR-183-mediated inhibition of macrophage infiltration, and dual luciferase reporter assay demonstrated that miR-183 directly targeted TGFα.

CONCLUSION

Our data demonstrate that miR-183 can ameliorate OA pain by inhibiting the TGFα-CCL2/CCR2 signalling axis, providing an excellent therapeutic target for OA treatment. Cite this article: Bone Joint Res 2021;10(8):548-557.

An implementation study of periarticular knee osteotomy in the treatment of knee osteoarthritis

OBJECTIVE

To analyze the clinical effects of periarticular knee osteotomy (PKO) in the treatment of knee osteoarthritis (KOA).

METHODS

A total of 180 patients with KOA admitted to our hospital were selected as the study subjects, and were divided into study group (90 cases) and control group (90 cases) in accordance with different intervention measures. The study group was treated with PKO, while the control group was treated with joint replacement. The perioperative indices, and postoperative pain degrees, knee joint function, quality of life, inflammatory factors and complications were compared between the two groups.

RESULTS

The control group was superior to the study group regarding the amount of preoperative bleeding, surgical duration, and incidence rate of complications, while the study group was superior to the control group regarding the long-term (over 2 years) knee joint function and quality of life (P < 0.05). There was no marked difference in the postoperative pain degrees and preoperative and postoperative levels of inflammatory factors between the two groups (P < 0.05).

CONCLUSION

PKO, exhibiting a high safety profile, can remarkably improve the joint pain symptoms, knee joint function, quality of life and symptoms of KOA in patients with KOA. Therefore, PKO is worthy of clinical promotion and implementation.

Impact of High Fat Diet and Ethanol Consumption on Neurocircuitry Regulating Emotional Processing and Metabolic Function

The prevalence of psychiatry disorders such as anxiety and depression has steadily increased in recent years in the United States. This increased risk for anxiety and depression is associated with excess weight gain, which is often due to over-consumption of western diets that are typically high in fat, as well as with binge eating disorders, which often overlap with overweight and obesity outcomes. This finding suggests that diet, particularly diets high in fat, may have important consequences on the neurocircuitry regulating emotional processing as well as metabolic functions. Depression and anxiety disorders are also often comorbid with alcohol and substance use disorders. It is well-characterized that many of the neurocircuits that become dysregulated by overconsumption of high fat foods are also involved in drug and alcohol use disorders, suggesting overlapping central dysfunction may be involved. Emerging preclinical data suggest that high fat diets may be an important contributor to increased susceptibility of binge drug and ethanol intake in animal models, suggesting diet could be an important aspect in the etiology of substance use disorders. Neuroinflammation in pivotal brain regions modulating metabolic function, food intake, and binge-like behaviors, such as the hypothalamus, mesolimbic dopamine circuits, and amygdala, may be a critical link between diet, ethanol, metabolic dysfunction, and neuropsychiatric conditions. This brief review will provide an overview of behavioral and physiological changes elicited by both diets high in fat and ethanol consumption, as well as some of their potential effects on neurocircuitry regulating emotional processing and metabolic function.

Electroacupuncture Prevents Osteoarthritis of High-Fat Diet-Induced Obese Rats

The effects of acupuncture on osteoarthritis (OA) pathogenesis have been demonstrated in vitro and in animal models. However, the potential for acupuncture to mediate protective effects on obese-induced OA has not been examined. Here, we investigated the effects of different acupuncture patterns on OA pathogenesis in high-fat diet- (HFD-) induced obese rats. After 12-week diet-induced obesity, obese rats were treated with three acupuncture protocols for 2 weeks, including ST36, GB34, and ST36+GB34. The results showed that the three acupuncture protocols both prevented obesity-induced cartilage matrix degradation and MMP expression and mitigated obesity-induced systemic and local inflammation but had different regulatory effects on lipid metabolism and gut microbiota disorder of obese-induced OA rats. Furthermore, the three acupuncture protocols increased the microbial diversity and altered the structure of community of feces in obese rats. We found that ST36 and GB34 could inhibit proinflammatory shift in the gut microbiome with an increase in the ratio of Bacteroidetes/Firmicutes and promote the recovery of relative abundance of Clostridium, Akkermansia, Butyricimonas, and Lactococcus. Although both ST36 and GB34 had an anti-inflammatory effect on serum inflammatory mediators, only the acupuncture protocol with both ST36 and GB34 could effectively inhibit LPS-mediated joint inflammation in obesity rats. Therefore, relieving obesity-related chronic inflammation, lipid metabolism disorder, and gut microbiota disorder may be an important mechanism for acupuncture with ST36 and GB34 to promote OA recovery.

Understanding cartilage protection in OA and injury: a spectrum of possibilities

BACKGROUND

Osteoarthritis (OA) is a prevalent musculoskeletal disease resulting in progressive degeneration of the hyaline articular cartilage within synovial joints. Current repair treatments for OA often result in poor quality tissue that is functionally ineffective compared to the hyaline cartilage and demonstrates increased failure rates post-treatment. Complicating efforts to improve clinical outcomes, animal models used in pre-clinical research show significant heterogeneity in their regenerative and degenerative responses associated with their species, age, genetic/epigenetic traits, and context of cartilage injury or disease. These can lead to variable outcomes when testing and validating novel therapeutic approaches for OA. Furthermore, it remains unclear whether protection against OA among different model systems is driven by inhibition of cartilage degeneration, enhancement of cartilage regeneration, or any combination thereof.

MAIN TEXT

Understanding the mechanistic basis underlying this context-dependent duality is essential for the rational design of targeted cartilage repair and OA therapies. Here, we discuss some of the critical variables related to the cross-species paradigm of degenerative and regenerative abilities found in pre-clinical animal models, to highlight that a gradient of regenerative competence within cartilage may exist across species and even in the greater human population, and likely influences clinical outcomes.

CONCLUSIONS

A more complete understanding of the endogenous regenerative potential of cartilage in a species specific context may facilitate the development of effective therapeutic approaches for cartilage injury and/or OA.

Mechanobiological model for simulation of injured cartilage degradation via pro-inflammatory cytokines and mechanical stimulus

Post-traumatic osteoarthritis (PTOA) is associated with cartilage degradation, ultimately leading to disability and decrease of quality of life. Two key mechanisms have been suggested to occur in PTOA: tissue inflammation and abnormal biomechanical loading. Both mechanisms have been suggested to result in loss of cartilage proteoglycans, the source of tissue fixed charge density (FCD). In order to predict the simultaneous effect of these degrading mechanisms on FCD content, a computational model has been developed. We simulated spatial and temporal changes of FCD content in injured cartilage using a novel finite element model that incorporates (1) diffusion of the pro-inflammatory cytokine interleukin-1 into tissue, and (2) the effect of excessive levels of shear strain near chondral defects during physiologically relevant loading. Cytokine-induced biochemical cartilage explant degradation occurs near the sides, top, and lesion, consistent with the literature. In turn, biomechanically-driven FCD loss is predicted near the lesion, in accordance with experimental findings: regions near lesions showed significantly more FCD depletion compared to regions away from lesions (p<0.01). Combined biochemical and biomechanical degradation is found near the free surfaces and especially near the lesion, and the corresponding bulk FCD loss agrees with experiments. We suggest that the presence of lesions plays a role in cytokine diffusion-driven degradation, and also predisposes cartilage for further biomechanical degradation. Models considering both these cartilage degradation pathways concomitantly are promising in silico tools for predicting disease progression, recognizing lesions at high risk, simulating treatments, and ultimately optimizing treatments to postpone the development of PTOA.

Post-traumatic osteoarthritis is a musculoskeletal disorder where inflammatory processes and abnormal joint loading predispose articular cartilage to degradation after a mechanical injury. Since inflamed and injured cartilage cannot be reversed back to healthy state, prevention of osteoarthritis progression is advisable, a prestigious goal where computational models could serve as tools. The current literature is short of computational models combining both biochemical and biomechanical aspects of osteoarthritis. Thus, here we implemented inflammation of living cartilage tissue followed by biochemical perturbations of tissue homeostasis and shear strain-induced biomechanical degradation in novel cell-to-tissue-level finite element models. The models presented in this paper and enriched by our experimental findings/previous literature provide profound new mechanobiological insights and predictions about cartilage degradation in injured and inflamed tissue under physiologically relevant mechanical loading. We suggest that mechanobiological computational models could be applied as in silico analysis tools that provide clinicians information of the personalized progression of post-traumatic osteoarthritis and decision-making guidance for treatment of the disease.

Anti-obesity potential of Moringa olifera seed extract and lycopene on high fat diet induced obesity in male Sprauge Dawely rats

Present research explored the anti-obesity effect of Moringa olifera seed oil extract and lycopene (LYC). Forty eight male Sprauge Dawely rats were divided equally into 6 groups. Group Ι (C) served as control, group ΙΙ (MC) was given Moringa olifera seed oil extract (800 mg/kg b.wt) for 8 weeks, group ΙΙΙ (LC) was given (20 mg/kg b.wt) LYC for 8 weeks, group ΙV (O) received high fat diet (HFD) for 20 weeks, group Ѵ (MO), was given HFD for 20 weeks and received (800 mg/kg b.wt) Moringa olifera seed oil extract for last 8 weeks and group ѴΙ (LO), received HFD for 20 weeks and was given (20 mg/kg b.wt) LYC for last 8 weeks. Hematology, lipid peroxidation and antioxidants, non-esterified fatty acids (NEFA), glucose, lipid profile, serum liver and kidney biomarkers, inflammatory markers, leptin, resistin and heart fatty acid binding protein (HFABP) were determined. Also histopathology for liver, kidney and aorta were performed besides immunohistochemistry (IHC) for aortic inducible nitric oxide synthase (iNOS). Administration of Moringa olifera seed oil extract and LYC significantly ameliorated the HFD induced hematological and metabolic perturbations as well as reduced leptin and resistin. Both treatments exerted these effects through promotion of antioxidant enzymes and reducing lipid peroxidation as well as inflammatory cytokines along with reduced iNOS protein expression. Administration of Moringa olifera seed oil extract and LYC have anti-obesity potential in HFD induced obesity in male Sprauge Dawely rats.

Consumption of a high energy density diet triggers microbiota dysbiosis, hepatic lipidosis, and microglia activation in the nucleus of the solitary tract in rats

Introduction

Obesity is a multifactorial chronic inflammatory disease. Consumption of high energy density (HED) diets is associated with hyperphagia, increased body weight and body fat accumulation, and obesity. Our lab has previously shown that short-term (4 weeks) consumption of a HED diet triggers gut microbiota dysbiosis, gut inflammation, and reorganization of the gut-brain vagal communication.

Objetives

The aim of this study was to investigate the effect of long-term (6 months) consumption of HED diet on body composition, gut microbiome, hepatocellular lipidosis, microglia activation in the nucleus of the solitary tract, and systemic inflammation.

Methods

Male Sprague–Dawley rats were fed a low energy density (LED) diet for 2 weeks and then switched to a HED diet for 26 weeks. Twenty-four-hour food intake, body weight, and body composition were measured twice a week. Blood serum and fecal samples were collected at baseline, 1, 4, 8, and 26 weeks after introduction of the HED diet. Serum samples were used to measure insulin, leptin, and inflammatory cytokines using Enzyme-linked Immunosorbent Assay. Fecal samples were assessed for 16 S rRNA genome sequencing.

Results

HED diet induced microbiota dysbiosis within a week of introducing the diet. In addition, there was significant microglia activation in the intermediate NTS and marked hepatic lipidosis after 4 weeks of HED diet. We further observed changes in the serum cytokine profile after 26 weeks of HED feeding.

Conclusions

These data suggest that microbiota dysbiosis is the first response of the organism to HED diets, followed by increased liver fat accumulation, microglia activation in the brain, and circulating levels of inflammatory markers. To our knowledge, this is the first study to present longitudinal and cross-sectional results on effect of long-term consumption of HED diets on all these parameters in a single cohort of animals.

Gut microbiota and obesity: Impact of antibiotics and prebiotics and potential for musculoskeletal health

Obesity is a complex disease with multiple contributing factors. One of the most intensely studied factors during the past decade has been the gut microbiota, which is the community of all microbes in the intestinal tract. The gut microbiota, via energy extraction, inflammation, and other actions, is now recognized as an important player in the pathogenesis of obesity. Dysbiosis, or an imbalance in the microbial community, can initiate a cascade of metabolic disturbances in the host. Early life is a particularly important period for the development of the gut microbiota, and perturbations such as with antibiotic exposure can have long-lasting consequences for host health. In early life and throughout the life span, diet is one of the most important factors that shape the gut microbiota. Although diets high in fat and sugar have been shown to contribute to dysbiosis and disease, dietary fiber is recognized as an important fermentative fuel for the gut microbiota and results in the production of short-chain fatty acids that can act as signaling molecules in the host. One particular type of fiber, prebiotic fiber, contributes to changes in the gut microbiota, the most notable of which is an increase in the abundance of Bifidobacterium. This review highlights our current understanding of the role of gut microbiota in obesity development and the ways in which manipulating the microbiota through dietary means, specifically prebiotics, could contribute to improved health in the host, including musculoskeletal health.

Impact of age on host responses to diet-induced obesity: Development of joint damage and metabolic set points

BACKGROUND

Osteoarthritis is one of the leading causes of pain and disability worldwide, and a large percentage of patients with osteoarthritis are individuals who are also obese. In recent years, a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage (both with and without the superimposition of trauma), which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators. Of note, there is a disparity between whether the dietary challenges commence at weaning, representing a weanling onset, or at skeletal maturity, representing an adult onset of obesity. We wished to evaluate the effect of the dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose (HFS) diet to determine whether these factors may result in disparate outcomes, as there is evidence suggesting that these factors result in differential metabolic disturbances. Based on dietary exposure time, we hypothesized that rats fed an HFS diet for 14 weeks from weaning (HFS Weanling) would demonstrate an increase in knee joint damage scores, whereas rats exposed to the HFS diet for 4 weeks, starting at 12 weeks of age (HFS Adult) and rats exposed to a standard chow diet (Chow) would not display an increase in knee joint damage scores.

METHODS

Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning (HFS Weanling) or an HFS diet for 4 weeks, starting at 12 weeks of age (HFS Adult). At sacrifice, joints were scored using the modified Mankin Criteria, and serum was analyzed for a defined subset of inflammatory markers (Interleukin-6, leptin, monocyte chemoattractant protein-1, and tumor necrosis factor α).

RESULTS

When the HFS Weanling and HFS Adult groups were compared, both groups had a similar percent of body fat, although the HFS Weanling group had a significantly greater body mass than the HFS Adult group. The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group. Although knee joint damage scores were low in all 3 groups, we found, contrary to our hypothesis, that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups. Furthermore, we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.

CONCLUSION

These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group. Interestingly, when assessing various serum proinflammatory markers, no significant differences were detected between the HFS Adult and HFS Weanling groups. Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated, these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced. Moreover, increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet.

An update on the association between metabolic syndrome and osteoarthritis and on the potential role of leptin in osteoarthritis

Metabolic syndrome (MetS) has been associated with osteoarthritis (OA). Leptin, which is one of the markers of MetS, has been associated with OA pathophysiology. This study aimed to provide an update on the association between MetS and OA and on the potential role of leptin in OA. In this review, we summarized the current knowledge of the association between MetS and OA and updated the evidence on the potential role of leptin in OA. Clinical studies have investigated the epidemiologic association between MetS or its components and OA. Results suggested strong epidemiologic associations between MetS and OA, especially in the Asian population. Animal studies also indicated that metabolic dysregulation may lead to OA pathogenesis. The systemic role of MetS in OA pathophysiology is associated with obesity-related inflammation, the beneficial role of n-3 polyunsaturated fatty acids and deleterious role of cholesterol, physical inactivity, hypertension-induced subchondral ischemia, dyslipidemia-induced ectopic lipid deposition in chondrocytes, hyperglycemia-induced local effects of oxidative stress and advanced glycation end-products, low-grade systemic inflammation, and obesity-related adipokines by inducing the expression of proinflammtory factors. Leptin levels in serum/plasma and synovial fluid were associated with joint pain, radiographic progression, bone formation biomarkers, cartilage volume, knee OA incidence, and total joint arthroplasty in OA patients. Elevated leptin expression and increased effect of leptin on infrapatellar fat pad, synovium, articular cartilage, and bone were also involved in the pathogenesis of OA. Current knowledge indicates a convincing epidemiologic association between MetS and OA, especially in the Asian population. Animal studies have also shown that metabolic dysregulation may lead to OA pathogenesis. Accumulating evidence suggests that leptin may play a potential role in OA pathogenesis. Therefore, leptin and its receptor may be an emerging target for intervention in metabolic-associated OA.

Effects of tetracycline on myocardial infarct size in obese rats with chemically-induced colitis

Background

Recent evidence suggests that antibiotic-induced changes in the composition of intestinal microflora, as well as the systemic immunoendocrine effects that result from them, can modulate myocardial tolerance to ischemia-reperfusion injury. The aim of this study was to investigate the effects of tetracycline (TTC) on myocardial infarct size in the isolated hearts obtained from obese rats with chemically-induced colitis (CIC). The association between TTC-induced changes in infarct size and intestinal microbiome composition as well as plasma levels of cytokines and short-chain fatty acids (SCFAs) was also studied.

Methods

Obesity was induced in Wistar rats by feeding them a high-fat, high-carbohydrate diet for five weeks. A single rectal administration of 3% acetic acid (2 mL) to the rats resulted in CIC. Healthy rats as well as obese rats with CIC received TTC (15 mg daily for 3 days) via gavage. The rats were euthanized, after which isolated heart perfusion with simulated global ischemia and reperfusion was performed. Infarct size was determined histochemically. Lipopolysaccharide (LPS) and cytokine levels in plasma were measured by enzyme-linked immunosorbent assay, whereas SCFA levels in plasma were measured by gas chromatography/mass spectrometry. The intestinal microbiome was analyzed using reverse transcription polymerase chain reaction.

Results

The treatment with TTC resulted in significant infarct size limitation (50 ± 7 vs. 62 ± 4% for the control mice, p < 0.05) in the hearts from intact animals. However, infarct size was not different between the control rats and the obese rats with CIC. Furthermore, infarct size was significantly larger in TTC-treated obese rats with CIC than it was in the control animals (77 ± 5%, p < 0.05). The concentrations of proinflammatory cytokines and LPS in serum were elevated in the obese rats with CIC. Compared to the control rats, the rats with both obesity and CIC had lower counts of Lactobacillus and Bifidobacterium spp. but higher counts of Escherichia coli. The effects of TTC on infarct size were not associated with specific changes in SCFA levels.

Conclusions

TTC reduced infarct size in the healthy rats. However, this effect was reversed in the obese animals with CIC. Additionally, it was associated with specific changes in gut microbiota and significantly elevated levels of cytokines and LPS.

Gut microbiota and osteoarthritis management: An expert consensus of the European society for clinical and economic aspects of osteoporosis, osteoarthritis and musculoskeletal diseases (ESCEO)

The prevalence of osteoarthritis (OA) increases not only because of longer life expectancy but also because of the modern lifestyle, in particular physical inactivity and diets low in fiber and rich in sugar and saturated fats, which promote chronic low-grade inflammation and obesity. Adverse alterations of the gut microbiota (GMB) composition, called microbial dysbiosis, may favor metabolic syndrome and inflammaging, two important components of OA onset and evolution. Considering the burden of OA and the need to define preventive and therapeutic interventions targeting the modifiable components of OA, an expert working group was convened by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) to review the potential contribution of GMB to OA. Such a contribution is supported by observational or dietary intervention studies in animal models of OA and in humans. In addition, several well-recognized risk factors of OA interact with GMB. Lastly, GMB is a critical determinant of drug metabolism and bioavailability and may influence the response to OA medications. Further research targeting GMB or its metabolites is needed to move the field of OA from symptomatic management to individualized interventions targeting its pathogenesis.

Calorie restriction with regular chow, but not a high-fat diet, delays onset of spontaneous osteoarthritis in the Hartley guinea pig model

BACKGROUND

Obesity is a leading risk factor for osteoarthritis (OA). In contrast, calorie restriction (CR) may lessen OA due to improved systemic inflammatory status and reduced weight-bearing. The aim of this study was to determine how CR with regular chow versus a high-fat diet (HFD) alters OA progression using the Hartley guinea pig model of disease.

METHODS

Twenty-four male guinea pigs were allocated to four groups at 2 months of age: (1) ad libitum regular chow (obese), (2) CR regular chow (lean), (3) ad libitum HFD, and (4) CR HFD. Animals in both HFD groups ate identical amounts and were combined into one HFD group for analyses. At 5 months, hind limbs were harvested for microcomputed tomography (microCT) and histopathologic evaluation of knee OA. Total body, gonad fat, and infrapatellar fat pad (IFP) masses were recorded. IFPs were collected for gene expression analysis. Immunohistochemistry for monocyte chemoattractant protein-1 (MCP-1) was performed on intact joints. Serum was utilized for protein C3 measurement. All data were compared using ordinary one-way ANOVA analyses with Tukey's post-hoc tests.

RESULTS

Body mass in the lean and HFD groups were similar and lower than the obese group. Despite this, gonad fat pads in the HFD group were comparable to the obese group. MicroCT and histologic OA scores were similar in obese and HFD groups; both scores were significantly lower in the lean group. Obese and HFD groups displayed increased gene expression of pro-inflammatory and catabolic mediators in IFPs relative to lean animals. Consistent with this, immunohistochemistry for MCP-1 in knee joints demonstrated strong positive staining in obese and HFD groups but was minimally detected in lean animals. Serum protein C3 levels were also statistically higher.

CONCLUSIONS

This study demonstrated that CR with a regular chow diet lessened knee OA in the Hartley guinea pig and was associated with decreased local and systemic inflammation compared to obese animals. HFD animals, although under CR conditions, had OA scores and inflammatory markers similar to obese animals. Thus, diet composition, and not solely body weight, may be a key factor in development of OA.

Envolvimento da inflamação subclínica e do estresse oxidativo na resistência à insulina associada a obesidade

A epidemia global da obesidade é um dos mais importantes problemas de saúde pública. Excessiva adiposidade é um crucial fator de risco no surgimento de várias doenças metabólicas, incluindo hipertensão, diabetes mellitus do tipo 2 e doença do fígado gorduroso não alcoólico.  Essas condições patológicas estão estritamente associadas com a resistência à insulina. Baseado nos esforços das últimas décadas, ocorreu marcante desenvolvimento na investigação sobre resistência à insulina induzida pela obesidade, especialmente em termos do mecanismo envolvido neste processo. Dentre esses, a inflamação subclínica ou crônica de baixo grau na obesidade tem sido o mais aceito. Este estado inflamatório é caracterizado por altos níveis circulantes de citocinas inflamatórias, incluindo TNF alfa e IL beta, e aumentado infiltração de macrófagos em tecidos periféricos. No entanto, recentemente, tem ocorrido grande interesse no papel que o estresse oxidativo desempenha na indução da resistência à insulina. Sob ativação, muitas células imunes geram radicais livres e, da mesma maneira, a síntese de espécies reativas de oxigênio promovem um status inflamatório. Estudos têm mostrado níveis elevados de espécies reativas e estresse oxidativo em indivíduos e animais obesos e/ou resistentes a insulina; isso parece estar associado a redução da função e da atividade e biogênese mitocondrial causada pelo aumento de lipídeos circulantes e maior deposição de gordura ectópica.  Essa revisão discorre sobre o mecanismo fisiopatológico de como a inflamação subclínica induz resistência à insulina na obesidade. Ainda, descreve o papel que o estresse oxidativo desempenha neste processo, bem como a produção de radicais livres na obesidade.

Effects of dietary fatty acid content on humeral cartilage and bone structure in a mouse model of diet-induced obesity

Obesity is a primary risk factor for osteoarthritis (OA), and previous studies have shown that dietary content may play an important role in the pathogenesis of cartilage and bone in knee OA. Several previous studies have shown that the ratio of ω-3 polyunsaturated fatty acids (PUFAs), ω-6 PUFAs, and saturated fatty acids can significantly influence bone structure and OA progression. However, the influence of obesity or dietary fatty acid content on shoulder OA is not well understood. The goal of this study was to investigate the role of dietary fatty acid content on bone and cartilage structure in the mouse shoulder in a model of diet-induced obesity. For 24 weeks, mice were fed control or high-fat diets supplemented with ω-3 PUFAs, ω-6 PUFAs, or saturated fatty acids. The humeral heads were analyzed for bone morphometry and mineral density by microCT. Cartilage structure and joint synovitis were determined by histological grading, and microscale mechanical properties of the cartilage extracellular and pericellular matrices were quantified using atomic force microscopy. Diet-induced obesity significantly altered bone morphology and mineral density in a manner that was dependent on dietary free fatty acid content. In general, high-fat diet groups showed decreased bone quality, with the ω-3 diet being partially protective. Cartilage mechanical properties and OA scores showed no changes with obesity or diet. These findings are consistent with clinical literature showing little if any relationship between obesity and shoulder OA (unlike knee OA), but suggest that diet-induced obesity may influence other joint tissues. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.