MCP-1 a promising biomarker for sarcopenic obesity in older adults

High levels of the monocyte chemotactic protein-1 (MCP-1) may help identify older adults at risk of sarcopenic obesity, according to a recent Singapore study.

“Our study has identified the association of increased body fat, higher trunk to limb fat ratio, and weaker physical strength in individuals with elevated MCP-1, a promising biomarker of adipose tissue inflammation that may have potential for identifying the at-risk group with sarcopenic obesity,” the researchers said.

The study included 200 community-dwelling older adults who were divided into elevated vs nonelevated subgroups based on cut-off values for MCP-1 (156.02 pg/mL) and dickkopft-1 (DKK-1; 606.31 pg/mL). Serum biomarker concentrations were measured using enzyme-linked immunosorbent assays, while body composition was assessed using dual energy x-ray absorptiometry. Physical performance and muscle strength were evaluated using validated questionnaires and the appropriate dynamometers.

Fat mass (20.71±6.26 vs 23.46±6.24 kg; p=0.014) and fat mass index (9.58±2.62 vs 8.40±2.67 kg/m²; p=0.013) were both significantly higher in participants with elevated MCP-1 levels. The same was true for percentage body fat (39.2±6.36 vs 35.9±6.94; p=0.008) and waist circumference (89.6±8.61 vs 85.7±9.02 cm; p=0.016). [J Frailty Sarcopenia Falls 2021;6:25-31]

MCP-1 also correlated with physical performance. Those with higher serum levels showed significantly weaker handgrip strength (22.16±5.94 vs 24.47±7.95; p=0.044) and were more likely to do worse in the repeated chair stand test (proportion who scored 4 points: 55.0 percent vs 71.3 percent; p=0.049).

Similarly, MCP-1 levels were significantly higher in participants with vs without sarcopenia (141.32±62.30 vs 122.23±50.89 pg/mL; p=0.046). Sarcopenia status was determined according to the 2019 Asian Working Group for Sarcopenia criteria.  

On the other hand, categorizing participants according to DKK-1 measurements yielded no such differences.

Multiple linear regression analysis confirmed that MCP-1 was significantly associated with various physical performance and body composition parameters, while DKK-1 was not.

For instance, MCP was linked to repeated chair stand results (β, 0.151; p=0.004), fat mass (β, 0.201; p=0.002) and fat mass index (β, 0.203; p=0.004), percentage body fat (β, 0.153; p=0.004), and waist circumference (β, 0.230; p=0.001).

In addition, the ratio between percentage fat in the trunk and in the leg (β, 0.134; p=0.04), as well as the trunk-limb fat mass ratio (β, 0.192; p=0.002) were both significantly associated with MCP-1. The same analysis confirmed that DKK-1 was not associated with any outcome variable of interest.

“Because our study is underpowered for further subgroup analyses by gender, we recommend future larger longitudinal studies with a higher representation of male participants adequately powered to examine if the effects of MCP-1 are gender-specific,” the researchers said.

Moreover, other factors common in ageing could have impacted the participants’ physical performance. These included lower bone density and pathologies of the joints and lungs. Biomechanical and endurance changes brought about by obesity may have also affected physical performance.

“The cross-sectional design of the study also precludes definitive conclusion about causality in the observed associations,” the researchers said, adding that “exploration of additional novel biomarkers is paramount to study the biological pathways associated with sarcopenia disease activity.”