Neuroinflammatory markers sTREM2 and YKL-40 in association with Alzheimer’s disease pathology: a systematic review and meta-analysis
摘要
Neuroinflammation is increasingly recognised as a key feature of Alzheimer’s Disease (AD) pathophysiology. Markers of glial reactivity, sTREM2 and YKL-40, are elevated in mild cognitive impairment (MCI) and AD, but their associations with core pathology across these stages have not yet been systematically investigated. This systematic review and meta-analysis examined their cross-sectional and longitudinal associations with core pathological biomarkers of AD, and examine how these relationships may evolve dynamically across the disease continuum.
MethodsA systematic literature search conducted across Medline, Embase, PsycINFO, PubMed and Scopus (PROSPERO: CRD420250653864) identified 42 studies for sTREM2 and 44 for YKL-40 that were included in this study.
ResultsMeta-analyses revealed that both markers showed robust positive associations with pTau181, tTau and NfL (pooled r = 0.31–0.55), including in covariate-adjusted correlations. In contrast, associations with Aβ pathology (CSF Aβ42/40, Aβ-PET) were weaker and not significant in covariate-adjusted estimates. Meta-regression analyses revealed that glial-tau associations were strongest in cognitively unimpaired (CU) individuals, and progressively weakened in MCI and AD, independent of age effects. Longitudinal data were limited and summarised descriptively; glial reactivity predicts increases in soluble CSF hyperphosphorylated tau pathology, yet is concurrently associated with slower accumulation of insoluble PET-detectable amyloid and tau aggregates.
ConclusionsOur findings indicate that sTREM2 and YKL-40 preferentially associate with tauopathy and neurodegeneration over pathological Aβ accumulation. The progressive attenuation of glial-pathology coupling may reflect glial saturation or “exhaustion” with disease progression, offering new insights into how impaired glial responses may be involved in AD pathophysiology.