Associations between inflammatory markers and muscle strength in older adults according to the presence or absence of obesity.

BACKGROUND: We investigated the association between inflammatory markers and muscle strength in older adults according to the presence or absence of obesity. Dynapenia is the age-related decline in muscle strength and results in negative outcomes to older adults. Accordingly, obesity is more prevalent throughout aging and is associated with comorbidities, such as type 2 diabetes, dyslipidemia and cardiovascular diseases. Both dynapenia and obesity are strongly linked to chronic inflammation, sharing common signaling pathways. METHODS: We recruited 247 older adults aged 60 or older and collected sociodemographic, anthropometric and metabolic data. Dynapenia was diagnosed according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria. Circulating inflammatory cytokines were measured in plasma using a multiplex panel kit. Anthropometric, sociodemographic, lipid profile, and fasting blood glucose were also assessed. RESULTS: Dynapenic participants were predominantly males (74.4%), had insufficiently active lifestyle and higher IL-10 plasma levels (0.95 pg/mL; 0.40-2.12). The prevalence of obesity was higher among non-dynapenic participants (45.3%; 95% CI, 37.7-53). In dynapenic older adults, obesity was predominant in males (53.6%) and subjects with normal muscle strength had higher serum levels of TNF-ß (0.63 pg/mL; 0.30-1.30) and lower hand-grip strength (24 kg; 20.00-28.00). Using a multivariate quantile regression analysis, we found a strong and negative association between IL-10 and muscle strength. CONCLUSIONS: This study can help to understand the association of inflammation, obesity and muscle strength to promote interventions in order to avoid or delay the negative outcomes associated with dynapenia and sarcopenia in older adults.

Higher levels of tumor necrosis factor ß are associated with frailty in socially vulnerable community-dwelling older adults.

BACKGROUND: The complex physiology underpinning the frailty syndrome is responsible for the absence of robust biomarkers that can be used for screening, diagnostic and/or prognostic purposes and has made clinical implementation difficult. Considering socially vulnerable populations, who have poor health status and increased morbidity and mortality, this scenario is even more complex. However, to the best of our knowledge, there are no studies available to investigate frailty biomarkers in socially vulnerable populations. Thus, the aim of this cross-sectional study was to identify potential blood-based biomarkers of frailty in a socially vulnerable population. METHODS: A sample consisting of 347 community-dwelling older people living in a context of high social vulnerability was divided into non-frail (robust), pre-frail and frail groups, according to modified Fried frailty phenotype criteria. Blood samples were collected and analyzed for basic metabolic parameters and for inflammatory cytokines. RESULTS: Levels of Interleukin-1α (IL-1α) and Tumor Necrosis Factor α (TNF-α) were significantly higher in pre-frail subjects, compared to non-frail ones. Tumor Necrosis Factor ß (TNF-ß) levels presented higher values in the frail compared to non-frail individuals. Interleukin-6 (IL-6) levels in pre-frail and frail subjects were significantly higher compared to the levels of non-frail subjects. Using an ordinal regression analysis, we observed that socially vulnerable older people at higher risk of developing frailty were subjects above 80 years old (OR: 2.5; 95% CI: 1.1-5.6) and who presented higher levels of TNF-ß (≥0.81 pg/mL, OR: 2.53; 95% CI: 1.3-4.9). CONCLUSION: As vulnerable populations continue to age, it is imperative to have a greater understanding of the frailty condition, identifying novel potential blood-based biomarkers. The results presented here could help to implement preventive healthcare strategies by evaluating frailty and at the same time measuring a set of inflammatory biomarkers, paying special attention to TNF-ß plasmatic levels.

Men with early degrees of knee osteoarthritis present functional and morphological impairments of the quadriceps femoris muscle.

OBJECTIVE: Quadriceps muscle weakness is common in knee osteoarthritis (OA). Reasons for weakness may include atrophy, reduction in the muscle fibers number, and changes in the muscle activation. It is uncertain when these muscular changes begin to appear. Therefore, the purpose of this study was to determine whether men with early stages of knee OA already had functional and quadriceps muscle morphologic alterations. DESIGN: Forty men were divided into two groups: control group (healthy subjects) and OA group (subjects with knee OA). A biopsy of the vastus lateralis muscle was performed for morphometric analysis. Isokinetic evaluation of knee extensor torque, concentric and eccentric (90 and 180 degrees/sec), was performed simultaneously with vastus lateralis electromyographic activity evaluation. RESULTS: Significant differences were found in knee extensor torque (P < 0.05) and in normalized root mean square (P < 0.01) during the eccentric contractions (both velocities), with higher values for the control group. No differences were found during concentric contractions. The OA group presented greater values of the minimum diameter of type 1 fibers and greater proportion and relative cross-sectional area of type 2b fibers (P < 0.05). CONCLUSIONS: Men with early stages of knee OA do not present alterations of concentric strength but had decreased eccentric strength and morphologic quadriceps muscle changes, indicating neuromuscular adaptations.

Expression of receptors of advanced glycation end product (RAGE) and types I, III and IV collagen in the vastus lateralis muscle of men in early stages of knee osteoarthritis.

Alterations in the contractile and non-contractile proteins of the skeletal muscle may reduce muscle function in knee osteoarthritis (OA), and the formation and accumulation of advanced glycation end products, particularly in collagen, can influence the quality of these muscle proteins. The objective of this study was to evaluate the reactivity of types I, III and IV collagen and the expression and localization of receptor for advanced glycation end products (RAGE) in the vastus lateralis (VL) muscle in early stages of knee OA. The hypothesis was that these patients present a higher expression of RAGE and increased immunoreactivity in the collagen. Thirty-five men were divided into two groups: the control group (CG; n = 17) and the osteoarthritis group (OAG; n = 18). All participants were submitted to a biopsy of the VL. The muscle samples were analyzed by immunohistochemistry for collagen and for RAGE and laminin. The expression of RAGE was counted (intracellular, extracellular and total). Student's t-test for independent samples and Mann-Whitney U test were used for the RAGE's intergroup analysis (α ≤ 0.05). A semiquantitative analysis was performed to assess the collagen reactivity. No significant differences were observed in the intracellular, extracellular or total localization of RAGE (p > 0.05). Higher immunoreactivity was observed in the OAG for all types of collagen, with more reactivity for collagen III and IV. We concluded that in the initial stages of knee OA, no differences were observed for RAGE levels between the groups. However, the OAG's higher collagen expression may represent adaptations for reducing muscle stiffness and avoiding injury.