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Category: Ankle Arthritis; Trauma Introduction/Purpose: Intraarticular pilon fractures have a high rate of posttraumatic osteoarthritis (PTOA) despite anatomic reduction of the articular surface. Elevated synovial inflammatory proteins triggered by injury contribute to PTOA development.MicroRNAs (miRNA), regulators of gene expression, are dysregulated in the cartilage of osteoarthritic joints, and their modulation may deter cartilage destruction. Specifically, miRNA-146a is associated with normal cartilage development and prevents overexpression of inflammatory proteins in degenerative osteoarthritis but is yet to be studied in clinical PTOA. This novel study aims to determine the effect of acute intraarticular pilon fracture on miRNA-146a expression and its association with inflammatory proteins. Methods: Bilateral ankles of patients with unilateral pilon fracture were aspirated for synovial fluid at the time of external fixation and/or open reduction internal fixation (ORIF). After processing, synovial fluid samples were sequenced for small RNA analysis. Measured levels of miRNA-146a in injured ankles were compared to the contralateral uninjured ankles, which served as baseline controls. Results: Five patients with unilateral pilon fractures consented to participate in the study. miRNA-146a was readily detectable in all patient samples. Using uninjured ankles (n=5) as a control, mean fold miRNA-146a expression was 1.0 ±0.93 [Mean ± Standard Deviation (SD)]. In comparison, mean fold miRNA-146a in injured ankles (n=5) was 0.4 ± 0.53(p=0.07). Additional results will be analyzed and available to present at the 2024 AOFAS Annual Meeting. Conclusion: Though not statistically significant, our preliminary data demonstrated that miRNA-146a was lower in injured ankles when compared to uninjured ankles. This study aims to better characterize the effect of acute pilon fracture on miRNA-146 expression and its association with inflammatory proteins. Anticipated results will help elucidate the role of miRNA-146a in the pathogenesis of PTOA following pilon fracture, impacting future PTOA research on the diagnostic and therapeutic capabilities of miRNAs.

Abstract Peripheral artery disease (PAD) is characterized by varying severity of arterial stenosis, exercise induced claudication, malperfused tissue precluding normal healing and skeletal muscle dysfunction. Revascularization interventions improve circulation, but post-reperfusion changes within the skeletal muscle are not well characterized. This study investigates if revascularization enhanced hemodynamics increases walking performance with concurrent improvement of mitochondrial function and reverses abnormal skeletal muscle morphological features that develop with PAD. Fifty-eight patients completed walking performance testing and muscle biopsy before and 6 months after revascularization procedures. Muscle fiber morphology, desmin structure, and mitochondria respiration assessments before and after the revascularization were evaluated. Revascularization improved limb hemodynamics, walking function, and muscle morphology. Qualitatively not all participants recovered normal structural architecture of desmin in the myopathic myofibers after revascularization. Heterogenous responses in the recovery of desmin structure following revascularization may be caused by other underlying factors not reversed with hemodynamic improvements. Revascularization interventions clinically improve patient walking ability and can reverse the multiple subcellular functional and structural abnormalities in muscle cells. Further study is needed to characterize desmin structural remodeling with improvements in skeletal muscle morphology and function.

OBJECTIVES:. Persistent skeletal muscle dysfunction in survivors of critical illness due to acute respiratory failure is common, but biological data elucidating underlying mechanisms are limited. The objective of this study was to elucidate the prevalence of skeletal muscle weakness and fatigue in survivors of critical illness due to COVID-19 and determine if cellular changes associate with persistent skeletal muscle dysfunction. DESIGN:. A prospective observational study in two phases: 1) survivors of critical COVID-19 participating in physical outcome measures while attending an ICU Recovery Clinic at short-term follow-up and 2) a nested cohort of patients performed comprehensive muscle and physical function assessments with a muscle biopsy; data were compared with non-COVID controls. SETTING:. ICU Recovery Clinic and clinical laboratory. PATIENTS/SUBJECTS:. Survivors of critical COVID-19 and non-COVID controls. INTERVENTIONS:. None. MEASUREMENTS AND MAIN RESULTS:. One hundred twenty patients with a median of 56 years old (interquartile range [IQR], 42–65 yr old), 43% female, and 33% individuals of underrepresented race attended follow-up 44 ± 17 days after discharge. Patients had a median Acute Physiology and Chronic Health Evaluation-II score of 24.0 (IQR, 16–29) and 98 patients (82%) required mechanical ventilation with a median duration of 14 days (IQR, 9–21 d). At short-term follow-up significant physical dysfunction was observed with 93% of patients reporting generalized fatigue and performing mean 218 ± 151 meters on 6-minute walk test (45% ± 30% of predicted). Eleven patients from this group agreed to participate in long-term assessment and muscle biopsy occurring a mean 267 ± 98 days after discharge. Muscle tissue from COVID exhibited a greater abundance of M2-like macrophages and satellite cells and lower activity of mitochondrial complex II and complex IV compared with controls. CONCLUSIONS:. Our findings suggest that aberrant repair and altered mitochondrial activity in skeletal muscle associates with long-term impairments in patients surviving an ICU admission for COVID-19.

Body composition (BC), a measure of body fat mass (FM), lean body mass (LBM), and bone mineral content (BMC), can be used as a predictor of cardiorespiratory fitness (CRF). Prior studies have established a relationship between BC and VO2max in healthy individuals over 35 years of age. However, this relationship is poorly understood in chronic disease populations. The focus of the study was to assess the relationship between BC, cardiorespiratory fitness, and chronic kidney disease (CKD). A cross-sectional analysis was conducted among 24 (9 males and 15 females) individuals diagnosed with mid-spectrum CKD (stages G2–G3b) who completed a health screening, dual-energy X-ray absorptiometry (DEXA) scan, and underwent a VO2max exercise test. Normality tests, descriptive statistics, Pearson’s correlations, t-tests, and ANOVAs were conducted in SAS v.9.4. The average percent body fat (%BF) was 36.28 ± 8.47%, LBM was 109.4 ± 29.1 lb, BMC was 2308.7 ± 735.1 g, and VO2max was 20.13 ± 5.04 mL/kg/min−1. BC was able to predict CRF via VO2max (R2 = 0.721, p < 0.001) and CKD stage (R2 = 0.390, p < 0.017). Positive correlations were observed in LBM (r = 0.750, p < 0.0018) and BMC (r = 0.647, p < 0.001), and negative correlations were observed with FM (r = −0.384, p < 0.032) and %BF (r = −0.802, p < 0.0001). BC was able to predict both CRF and CKD stages, with significant associations observed between BC, VO2max, and CKD stage. The progression of the CKD stage was associated with lower LBM, BMC, and VO2max values, indicating a graded effect of BC on CRF and CKD stage.

Abstract Background Skeletal muscle (SkM) is a large, secretory organ that produces and releases myokines that can have autocrine, paracrine, and endocrine effects. Whether extracellular vesicles (EVs) also play a role in the SkM adaptive response and ability to communicate with other tissues is not well understood. The purpose of this study was to investigate EV biogenesis factors, marker expression, and localization across cell types in the skeletal muscle. We also aimed to investigate whether EV concentrations are altered by disuse atrophy. Methods To identify the potential markers of SkM-derived EVs, EVs were isolated from rat serum using density gradient ultracentrifugation, followed by fluorescence correlation spectroscopy measurements or qPCR. Single-cell RNA sequencing (scRNA-seq) data from rat SkM were analyzed to assess the EV biogenesis factor expression, and cellular localization of tetraspanins was investigated by immunohistochemistry. Finally, to assess the effects of mechanical unloading on EV expression in vivo, EV concentrations were measured in the serum by nanoparticle tracking analysis in both a rat and human model of disuse. Results In this study, we show that the widely used markers of SkM-derived EVs, α-sarcoglycan and miR-1, are undetectable in serum EVs. We also found that EV biogenesis factors, including the tetraspanins CD63, CD9, and CD81, are expressed by a variety of cell types in SkM. SkM sections showed very low detection of CD63, CD9, and CD81 in myofibers and instead accumulation within the interstitial space. Furthermore, although there were no differences in serum EV concentrations following hindlimb suspension in rats, serum EV concentrations were elevated in human subjects after bed rest. Conclusions Our findings provide insight into the distribution and localization of EVs in SkM and demonstrate the importance of methodological guidelines in SkM EV research.

The onset of menopause elicits changes in body composition that negatively influence adipokine levels. Consequently, various health risk factors (e.g., cardiovascular disease, osteoporosis, physical inactivity, obesity, arterial hypertension, hypercholesterolemia, sarcopenia) are influenced by adipokines due to changes in body composition after menopause. Thus, improvements in body composition are considered the primary influencer of adipokines. Though several therapeutic interventions (e.g., medication, diet, meditation, exercise) are employed to target changes in body composition, resistance training appears to be more effective in positively improving body composition through changes in lean-muscle mass/fat-mass ratio. However, due to the lack of research, very little is known about adipokines' anti/inflammatory response in postmenopausal women after completing resistance training. Most resistance training studies in postmenopausal women have focused on leptin, adiponectin, and resistin, with limited research assessing other adipokines that are important in metabolic regulation and inflammatory processes. Additionally, the consistency of resistance training protocols as an intervention is not standardized or fully recognized. Therefore, the focus of this review is to establish a more comprehensive understanding of the benefits of resistance training on influencing adipokine levels based on changes to total body composition in postmenopausal women.

Introduction: Apolipoprotein E (ApoE) has been shown to be necessary for proper skeletal muscle regeneration. Consistent with this finding, single-cell RNA-sequencing analyses of skeletal muscle stem cells (MuSCs) revealed that Apoe is a top marker of quiescent MuSCs that is downregulated upon activation. The purpose of this study was to determine if muscle regeneration is altered in mice which harbor one of the three common human ApoE isoforms, referred to as ApoE2, E3 and E4.Methods: Histomorphometric analyses were employed to assess muscle regeneration in ApoE2, E3, and E4 mice after 14 days of recovery from barium chloride-induced muscle damage in vivo, and primary MuSCs were isolated to assess proliferation and differentiation of ApoE2, E3, and E4 MuSCs in vitro.Results: There was no difference in the basal skeletal muscle phenotype of ApoE isoforms as evaluated by section area, myofiber cross-sectional area (CSA), and myonuclear and MuSC abundance per fiber. Although there were no differences in fiber-type frequency in the soleus, Type IIa relative frequency was significantly lower in plantaris muscles of ApoE4 mice compared to ApoE3. Moreover, ApoE isoform did not influence muscle regeneration as assessed by fiber frequency, fiber CSA, and myonuclear and MuSC abundance. Finally, there were no differences in the proliferative capacity or myogenic differentiation potential of MuSCs between any ApoE isoform.Discussion: Collectively, these data indicate nominal effects of ApoE isoform on the ability of skeletal muscle to regenerate following injury or the in vitro MuSC phenotype.

Abstract Recently, the gut microbiome has emerged as a potent modulator of exercise‐induced systemic adaptation and appears to be crucial for mediating some of the benefits of exercise. This study builds upon previous evidence establishing a gut microbiome‐skeletal muscle axis, identifying exercise‐induced changes in microbiome composition. Metagenomics sequencing of fecal samples from non‐exercise‐trained controls or exercise‐trained mice was conducted. Biodiversity indices indicated exercise training did not change alpha diversity. However, there were notable differences in beta‐diversity between trained and untrained microbiomes. Exercise significantly increased the level of the bacterial species Muribaculaceae bacterium DSM 103720. Computation simulation of bacterial growth was used to predict metabolites that accumulate under in silico culture of exercise‐responsive bacteria. We identified acetate and succinate as potential gut microbial metabolites that are produced by Muribaculaceae bacterium, which were then administered to mice during a period of mechanical overload‐induced muscle hypertrophy. Although no differences were observed for the overall muscle growth response to succinate or acetate administration during the first 5 days of mechanical overload‐induced hypertrophy, acetate and succinate increased skeletal muscle mitochondrial respiration. When given as post‐biotics, succinate or acetate treatment may improve oxidative metabolism during muscle hypertrophy.

Adiponectin (adipoq), the most abundant hormone in circulation, has many beneficial effects on the cardiovascular system, in part by preserving the contractile phenotype of vascular smooth muscle cells (VSMCs). However, the lack of adiponectin or its receptor and treatment with recombinant adiponectin have shown contradictory effects on plaque in mice. RNA sequence of Adipoq+/+ and adipoq−/− VSMCs from male aortas identified a critical role for adiponectin in AKT signaling, the extracellular matrix (ECM), and TGF-β signaling. Upregulation of AKT activity mediated proliferation and migration of adipoq−/− cells. Activation of AMPK with metformin or AdipoRon reduced AKT-dependent proliferation and migration of adipoq−/− cells but did not improve the expression of contractile genes. Adiponectin deficiency impaired oxidative phosphorylation (OXPHOS), increased expression of glycolytic enzymes, and elevated mitochondrial reactive oxygen species (ROS) (superoxide, and hydrogen peroxide). Anti-atherogenic mechanisms targeted the ECM in adipoq−/− cells, downregulating MMP2 and 9 and upregulating decorin (DCN) and elastin (ELN). In vivo, the main sex differences in protein expression in aortas involved a more robust upregulation of MMP3 in females than males. Females also showed a reduction in DCN, which was not affected in males. Our study uncovered the AKT/MAPK/TGF-β network as a central regulator of VSMC phenotype.

Aerobic exercise, specifically high-intensity interval exercise (HIIE), and its effects on renal health and filtration (RHF) are not well understood. Several studies support incorporating contemporary biomarkers serum cystatin C (CyC) and urine epidermal growth factor (uEGF) to combat the volatility of serum creatinine (sCr). Using these biomarkers, we examined the acute influences HIIE has on RHF to determine if there is a ceiling effect in healthy populations. The purpose was to determine the influence of an acute bout of HIIE on RHF. Thirty-six participants (n = 22 males; n = 14 females; age 37.6 ± 12.4 years.; BF% 19.2 ± 7.1%; VO2max 41.8 + 7.4 mL/kg/min) completed 30 min of HIIE on a treadmill (80% and 40% of VO2reserve in 3:2 min ratio). Blood and urine samples were obtained under standardized conditions before, 1 h, and 24 h post-exercise. CyC, sCR, uEGF, urine creatinine (uCr), uCr/uEGF ratio, and multiple estimates of glomerular filtration rate (eGFR) Modification of Diet in Renal Disease (MDRD) and CKD-EPI equations were used. The analysis employed paired sample t-tests and repeated measures ANOVAs. CyC, uEGF, uCr, and uCr/uEGF ratio concentrations were not altered between timepoints. sCr increased 1 h post-exercise (p > 0.002) but not at 24 h post-exercise. eGFR decreased in the MDRD and CKD-EPI equations at 1 h (p > 0.012) with no changes at 24 h post-exercise. CyC and sCr/CyC demonstrated no significant changes. CyC and uEGF are not altered by acute HIIE. The results demonstrate a potential ceiling effect in contemporary and traditional biomarkers of RHF, indicating improvements in RHF may be isolated to populations with reduced kidney function.

Peripheral artery disease (PAD) is a disease of atherosclerosis in the lower extremities. PAD carries a massive burden worldwide, while diagnosis and treatment options are often lacking. One of the key points of research in recent years is the involvement of microRNAs (miRNAs), which are short 20-25 nucleotide single-stranded RNAs that can act as negative regulators of post-transcriptional gene expression. Many of these miRNAs have been discovered to be misregulated in PAD patients, suggesting a potential utility as biomarkers for PAD diagnosis. miRNAs have also been shown to play an important role in many different pathophysiological aspects involved in the initiation and progression of the disease including angiogenesis, hypoxia, inflammation, as well as other cellular functions like cell proliferation and migration. The research on miRNAs in PAD has the potential to lead to a whole new class of diagnostic tools and treatments.

Aerobic exercise elicits a multitude of physiological improvements in both healthy and diseased populations. However, acute changes in renal health and filtration with aerobic exercise remain difficult to quantify by traditional biomarkers to estimate glomerular filtration rate (eGFR). This study aimed to determine if an acute bout of moderate-intensity aerobic exercise transiently improves non-traditional biomarkers when compared to traditional biomarkers of renal health and filtration in individuals without cardiometabolic diseases. Thirty-nine participants (n = 18 men; n = 21 women; age 32.5 + 12.6 yr; height 171.1 + 11.4 cm; weight 78.7 + 15.6 kg; BMI 27.1 + 5.8) completed a single bout of moderate-intensity (50–60% HRR) aerobic exercise. Blood and urine samples were collected and compared before and post-exercise. Serum creatinine, urine epidermal growth factor (uEGF), uEGF/urine creatinine ratio (uEGFR), and cystatin C (CyC) were measured. In addition, eGFR-MDRD and the CKD-epidemiology equations were used to analyze renal clearance. Relative to pre-exercise measures: serum creatinine (p = 0.26), uEGF (p = 0.35), and uEGFR (p = 0.09) remained unchanged, whereas cystatin C (p = 0.00) significantly increased post-exercise. CyC eGFR was the only estimator of renal filtration to significantly change (p = 0.04). In conclusion, CyC is the only biomarker of renal health and filtration to significantly increase after aerobic exercise. Further investigation focused on sampling time and exercise-intensity is needed to solidify the current understanding of renal health and filtration.

Hydrogen sulfide (H2S) is an endogenous signaling molecule which is important for cardiovascular health, but its mechanism of action remains poorly understood. Here, we report measurements of H2S as well as its oxidized metabolites, termed small oxoacids of sulfur (SOS = HSOH and HOSOH), in four human primary vascular cell lines: smooth muscle and endothelial cells derived from both human arterial and coronary tissues. We use a methodology that targets small molecular weight sulfur species; mass spectrometric analysis allows for species quantification to report cellular concentrations based on an H2S calibration curve. The production of H2S and SOS is orders of magnitude higher in smooth muscle (nanomolar) as compared to endothelial cell lines (picomolar). In all the primary lines measured, the distributions of these three species were HOSOH >H2S > HSOH, with much higher SOS than seen previously in non-vascular cell lines. H2S and SOS were effluxed from smooth muscle cells in higher concentrations than endothelial cells. Aortic smooth muscle cells were used to examine changes under hypoxic growth conditions. Hypoxia caused notable increases in HSOH and ROS, which we attribute to enhanced sulfide quinone oxidase activity that results in reverse electron transport.

Peripheral artery disease (PAD) pathophysiology extends beyond hemodynamics to include other operating mechanisms, including endothelial dysfunction. Oxidative stress may be linked to endothelial dysfunction by reducing nitric oxide (NO) bioavailability. We aimed to investigate whether the NO system and its regulators are altered in the setting of PAD and to assess the relationship between NO bioavailability and oxidative stress. Sera from 35 patients with intermittent claudication (IC), 26 patients with critical limb ischemia (CLI), and 35 non-PAD controls were analyzed to determine levels of tetrahydrobiopterin (BH4), dihydrobiopterin (BH2), nitrate/nitrite (nitric oxides, or NOx), arginine, citrulline, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the oxidative stress markers 8-Oxo-2′-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), advanced glycation end products (AGEs), and protein carbonyls. NOx was significantly lower in IC and CLI patients compared to controls in association with elevated oxidative stress, with the greatest NOx reductions observed in CLI. Compared with controls, IC and CLI patients had reduced BH4, elevated BH2, and a reduced BH4/BH2 ratio. SDMA, the arginine/SDMA ratio, and the arginine/ADMA ratio were significantly higher in CLI patients. The NO system and its regulators are significantly compromised in PAD. This dysregulation appears to be driven by increased oxidative stress and worsens as the disease progresses from claudication to CLI.