Associations of plasma neurofilament light chain and progranulin with frailty in older adults

Biomarkers of aging in frailty and age-associated disorders: State of the art and future perspective

According to the Geroscience concept that organismal aging and age-associated diseases share the same basic molecular mechanisms, the identification of biomarkers of age that can efficiently classify people as biologically older (or younger) than their chronological (i.e. calendar) age is becoming of paramount importance. These people will be in fact at higher (or lower) risk for many different age-associated diseases, including cardiovascular diseases, neurodegeneration, cancer, etc. In turn, patients suffering from these diseases are biologically older than healthy age-matched individuals. Many biomarkers that correlate with age have been described so far. The aim of the present review is to discuss the usefulness of some of these biomarkers (especially soluble, circulating ones) in order to identify frail patients, possibly before the appearance of clinical symptoms, as well as patients at risk for age-associated diseases. An overview of selected biomarkers will be discussed in this regard, in particular we will focus on biomarkers related to metabolic stress response, inflammation, and cell death (in particular in neurodegeneration), all phenomena connected to inflammaging (chronic, low-grade, age-associated inflammation). In the second part of the review, next-generation markers such as extracellular vesicles and their cargos, epigenetic markers and gut microbiota composition, will be discussed. Since recent progresses in omics techniques have allowed an exponential increase in the production of laboratory data also in the field of biomarkers of age, making it difficult to extract biological meaning from the huge mass of available data, Artificial Intelligence (AI) approaches will be discussed as an increasingly important strategy for extracting knowledge from raw data and providing practitioners with actionable information to treat patients.

Neurofilament-light chains (NF-L), a biomarker of neuronal damage, is increased in patients with severe sarcopenia: results of the SarcoPhAge study

BACKGROUND

As clinical tests, such as gait speed, require nervous system integrity to be performed properly, sarcopenia shares features with neurological diseases. Neurofilament light chains (NF-L) are now used as a blood-biomarker of neuronal damage, and its expression might be altered in sarcopenia. We aimed to assess NF-L concentrations in a large cohort of older individuals screened for sarcopenia.

METHODS

The SarcoPhAge cohort is a Belgian cohort of 534 community-dwelling older adults with an ongoing 10-year follow-up. Sarcopenia diagnosis was established at inclusion according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria. Muscle strength was evaluated with a hydraulic hand dynamometer, appendicular lean mass by Dual-Energy X-ray Absorptiometry (DXA) and physical performance by the Short Physical Performance Battery (SPPB). NF-L was measured on all available sera collected at the time of inclusion (n = 409) using SiMoA technology (Quanterix°).

RESULTS

In the multivariate model, NF-L was associated with performance tests such as gait speed (p < 0.0001) and SPPB scores (p = 0.0004). An association was also observed with muscle strength (p = 0.0123) and lean mass (p = 0.0279). In the logistic regression model, NF-L was an independent predictor of severe sarcopenia (p = 0.0338; OR = 20.0; 95% CI 1.39-287.7) with satisfactory diagnostic accuracy (AUC: 0.828) and subjects with an SPPB score ≤ 8 had higher odds of having increased NF-L (p < 0.0001; OR = 23.9; 95% CI 5.5-104).

CONCLUSIONS

These data highlight the potential for using NF-L to investigate the pathophysiology of sarcopenia severity and the neurological features associated with performance tests. However, these results need to be confirmed with other cohorts in different settings.

Serum progranulin as a potential biomarker for frailty in Chinese older adults

BACKGROUND

Frailty can increase adverse health outcomes in older adults. Progranulin is a secreted glycoprotein involved in regulating various biological processes. Different perspectives exist on the relationship between progranulin and frailty.

AIMS

We aimed to evaluate the association of progranulin with frailty in older Chinese adults.

METHODS

We included 265 older in-patients who were divided into the robust (n = 31), pre-frail (n = 116) and frail (n = 118) groups according to the FRAIL scale. Serum IL-6, CXCL-10, progranulin, and CRP levels were assayed. Spearman's correlation and logistic regression models were used to analyze the association of serum biomarkers with frailty, and ROC was used to evaluate the diagnostic progranulin value for frailty.

RESULTS

The frail group was older and had lower BMI, higher prevalence of coronary heart disease, worse grip strength and walking speed, and higher IL-6, CXCL-10, progranulin, and CRP serum levels than the robust and pre-frail groups. Progranulin levels were negatively correlated with grip strength (r = - 0.152, p = 0.016) and positively correlated with IL-6 (r = 0.207, p = 0.001) and CXCL-10 (r = 0.160, p = 0.009) after adjusting for age and sex. Furthermore, progranulin remained associated with frailty after adjusting for age, sex, BMI, smoking, chronic diseases, and pro-inflammatory cytokines (OR = 1.003, 95% CI 1.001-1.006, p = 0.022). The AUC of serum progranulin levels for diagnostic frailty was 0.927 (95% CI 0.896-0.958, p < 0.001).

CONCLUSION

High serum progranulin levels were observed in frail older adults and were associated with worse physical function and increased chronic inflammation. Progranulin may be a potential biomarker for frailty.

Role of autoantibodies and blood-brain barrier leakage in cognitive impairment in systemic lupus erythematosus

Objective

Cognitive impairment is common in patients with SLE but the cause is unknown. The current cross-sectional study examined the association between select SLE-related autoantibodies, other serological biomarkers and extensive blood–brain barrier (BBB) leakage in patients with SLE with and without cognitive impairment. In addition, we determined whether the relationship between SLE autoantibodies, other biomarkers and cognitive impairment differed depending on the presence or absence of concurrent extensive BBB leakage.

Methods

Consecutive patients with SLE, recruited from a single academic medical centre, underwent formal neuropsychological testing for assessment of cognitive function. On the same day, BBB permeability was determined using dynamic contrast-enhanced MRI scanning. SLE autoantibodies and other serological biomarkers were measured. Regression modelling was used to determine the association between cognitive impairment, extensive BBB leakage and autoantibodies/biomarkers.

Results

There were 102 patients with SLE; 90% were female and 88% were Caucasian, with a mean±SD age of 48.9±13.8 years. The mean±SD SLE disease duration was 14.8±11.0 years. Impairment in one or more cognitive tests was present in 47 of 101 (47%) patients and included deficits in information processing speed (9%), attention span (21%), new learning (8%), delayed recall (15%) and executive abilities (21%). Extensive BBB leakage was present in 20 of 79 (25%) patients and was associated with cognitive impairment (15 of 20 (75%) vs 24 of 59 (41%); p=0.01) and shorter disease duration (median (IQR): 7 (8–24 years) vs 15 (2–16 years); p=0.02). No serological parameters were associated with extensive BBB leakage and there was no statistically significant association between cognitive impairment and circulating autoantibodies even after adjusting for BBB leakage.

Conclusions

Extensive BBB leakage alone was associated with cognitive impairment. These findings suggest that BBB leakage is an important contributor to cognitive impairment, regardless of circulating SLE-related autoantibodies.