Sex-Specific Associations between Serum IL-16 Levels and Sarcopenia in Older Adults

Role of IL-16 in age-related skeletal muscle atrophy: an integrated study

BACKGROUND

In this study, we aim to explore the roles of IL-16 in sarcopenia based on older orthopedic patients and animal research.

METHODS

This clinical research in this study was an observational investigation and included all the older patients with orthopedic trauma admitted to our department between January 2021 and January 2022. Patients were identified with sarcopenia if they have both low hand grip strength (HGS) and low appendicular skeletal muscle mass (ASM). Propensity score matching (PSM) was performed to reduce the bias caused by the co-factors and levels of IL-16 between normal patients and patients with sarcopenia were compared. In animal research, mice were treated with IL-16 to identify the effects of IL-16 on muscle function and muscle mass. Then the sarcopenia models were established and the anti-IL-16 was performed to identify the potential therapeutical effect of targeting IL-16.

RESULTS

421 individuals were included in the clinical study, and 77 were identified as sarcopenia. In the matched populations, the serum levels of IL-16 of individuals with low HGS, ASM, and sarcopenia were significantly higher than normal individuals (all p < 0.001). The mice treated with IL-16 showed significantly impaired muscle function and physical performance and loss of muscle mass. Using anti-IL-16 antibodies may rescue the sarcopenia traits caused by botulinum toxin type A.

CONCLUSION

Individuals with high levels of IL-16 may have a significantly high risk of sarcopenia. IL-16 impairs muscle function and physical performance and leads to muscle atrophy in mice, and these effects could be reduced by targeting IL-16.

Inflamm-ageing: How cytokines and nutrition shape the trajectory of ageing

Population ageing is increasing in prevalence in most developed countries. Ageing is the decline of functional properties at the cellular, tissue, and organ level. Biochemical changes that occur in all organisms that experience biological ageing are referred to as the "Hallmarks of ageing". Inflammation is a common denominator of the hallmarks of ageing, being mechanistically involved in most age-related health consequences. Inflamm-ageing refers to age-related changes in the inflammatory and immune systems which somehow drive the ageing process towards healthy or unhealthy ageing. Current evidences, support that, reversing the age-related pro-inflammatory status of inflamm-ageing, is able to modulate most hallmarks of ageing. Inflamm-ageing is associated with increased levels of pro-inflammatory molecules (e.g. cytokines, chemokines), ultimately producing a chronic low-grade inflammatory state typically observed in older individuals. It is commonly accepted that, the balance between pro- and anti-inflammatory cytokines/chemokines is one of the factors determining whether healthy or unhealthy ageing occurs. Malnutrition and nutritional imbalances, are highly prevalent in the elderly, playing a role in driving the balance of pro- and anti-inflammatory immunoactive molecules. In particular, malnutrition is a major risk factor for sarcopenia, a phenomenon characterized by loss of muscle mass, which is often referred to as the biological basis for frailty. Given the close relationship between malnutrition and sarcopenia, there is also evidence for a link between malnutrition and frailty. Indeed, changes in cytokine/chemokine levels in elderly patients with malnutrition were demonstrated. The demonstration that specific cytokines play a role in modulating appetite and nutrient sensing and taste reception, provided further evidence for the existence of a link between inflamm-ageing, nutrition and cytokines in shaping the trajectory of ageing. The present review will overview current evidence supporting the role of specific circulating cytokines and chemokines in the relationship between ageing, inflammation, and malnutrition.

Mapping the causal associations of cytokines with sarcopenia and aging traits: Evidence from bidirectional Mendelian randomization

BACKGROUND

Cytokines and growth factors may serve as a bridge in studying the causal relationships between inflammaging and sarcopenia due to their roles in inflammaging. In this study, we aim to explore the causal association of cytokines with sarcopenia and aging traits and further identify the significant inflammation factors.

METHODS

Bidirectional Mendelian randomization (MR) analysis was used to identify the causality. Forty-one kinds of circulation cytokines and growth factors were set as exposures, and the data were from a summary genome-wide association study (GWAS) containing three cohorts with 8293 healthy participants of European ancestry from 1983 to 2011. Hand grip strength, adjusted appendicular lean mass (AALM), usual walking pace, moderate-to-vigorous physical activity (MVPA) levels, able to walk or cycle unaided for 10 min (AWCU10) and telomere length were selected as outcomes. Data for outcomes were obtained from meta-GWAS and the UK Biobank, and sample sizes ranged from 69 537 to 472 174. Low hand grip strength was defined by the European Working Group on Sarcopenia in Older People (EWGSOP) and Foundation for the National Institutes of Health (FNIH) cut-off points, respectively. Other outcome traits were defined and measured according to the UK Biobank and raw cohorts' criteria. We set two significance thresholds for single nucleotide polymorphisms (SNPs) associated with exposures to obtain adequate SNPs (5 × 10-6 and 5 × 10-8). Inverse-variance weighted, MR-Egger and weighted median were employed to estimate the causality.

RESULTS

Twenty-seven factors were identified to relate to sarcopenia and aging traits causally, and most were associated with only one outcome trait. IL16 (interleukin-16), CTACK (cutaneous T-cell attracting chemokine), MIP1b (macrophage inflammatory protein 1b) and PDGFbb (platelet-derived growth factor BB) were proven to relate causally to at least one sarcopenia and aging trait in both analyses with two significance thresholds. IL16 was causally associated with hand grip strength (0.977 [0.956-0.998] for EWGSOP and 0.933 [0.874-0.996] for FNIH), AALM (0.991 [0.984, 0.998]), MVPA (0.997 [0.995-1.000]) and AWCU10 (1.008 [1.003-1.013]). CTACK was proven to relate causally to hand grip strength (1.013 [1.007-1.019] for EWGSOP and 1.090 [1.041-1.142] for FNIH), AWCU10 (0.990 [0.986-0.994]) and telomere length (0.998 [0.983-0.994]). The results indicated that MIP1b has a causal effect on hand grip strength (1.032 [1.001-1.063] for EWGSOP), AWCU10 (0.994 [0.988-1.000] and 0.993 [0.988-0.998]) and telomere length (1.006 [1.000-1.012]). PDGFbb may causally relate to AALM (1.016 [1.001-1.030]) and telomere length (1.011 [1.007-1.015]). Reserve MR analyses also proved their unidirectional causal effects.

CONCLUSIONS

Twenty-seven factors were causally related to sarcopenia and aging traits, and the causal effects of IL16, CTACK, MIP1b and PDGFbb were proven in both analyses with two significance thresholds.

Estimation of Sarcopenia Indices in Women from Saudi Arabia in Relation to Menopause and Obesity: Cross-Sectional Comparative Study

Sarcopenia prevalence depends on the definition, and ethnicity must be considered when setting reference values. However, there is no specific cut-off for sarcopenia in Saudi women. Accordingly, we aimed to establish a cut-off value for sarcopenia in Saudi women. We determined the prevalence of sarcopenia in terms of low handgrip strength (HGS) in postmenopausal women using the EWGSOP2 value, redefined a specific cut-off for low HGS derived from Saudi premenopausal women, re-determined the prevalence of low HGS using the new cut-off, and analyzed the proportion of low HGS in women with obesity compared to those without obesity. Following EWGSOP2 guidelines, we defined probable sarcopenia and set new HGS values. We assessed HGS and body composition in 134 pre/postmenopausal women. Probable sarcopenia prevalence was calculated using EWGSOP2's HGS of 16 kg and new cut-offs from young premenopausal women without obesity. HGS 10 and 8 kg cut-offs were calculated from premenopausal Saudi women's mean -2 SDs and mean -2.5 SDs. Using the HGS 16 kg cut-off, sarcopenia prevalence was 44% in postmenopausal and 33.89% in premenopausal women. Applying the new HGS 10 kg and 8 kg cut-offs, the prevalence was 9.33% and 4%, respectively, in postmenopausal and 5% and 3.40%, respectively, in premenopausal women. Women with obesity had a higher proportion of low HGS across all cut-offs. We suggest that EWGSOP2 cut-offs may not be adaptable for Saudi women. Considering body composition differences between Saudis and Caucasians, our proposed HGS cut-offs appear more relevant.