Microglia are the only resident innate immune cells derived from the mesoderm in the nerve tissue. They play a role in the development and maturation of the central nervous system (CNS). Microglia mediate the repair of CNS injury and participate in endogenous immune response induced by various diseases by exerting neuroprotective or neurotoxic effects. Traditionally, microglia are considered to be in a resting state, the M0 type, under physiological conditions. In this state, they perform immune surveillance by constantly monitoring pathological responses in the CNS. In the pathological state, microglia undergo a series of morphological and functional changes from the M0 state and eventually polarize into classically activated microglia (M1) and alternatively activated microglia (M2). M1 microglia release inflammatory factors and toxic substances to inhibit pathogens, while M2 microglia exert neuroprotective effects by promoting nerve repair and regeneration. However, in recent years, the view regarding M1/M2 polarization of microglia has gradually changed. According to some researchers, the phenomenon of microglia polarization is not yet confirmed. The M1/M2 polarization term is used for a simplified description of its phenotype and function. Other researchers believe that the microglia polarization process is rich and diverse, and consequently, the classification method of M1/M2 has limitations. This conflict hinders the academic community from establishing more meaningful microglia polarization pathways and terms, and therefore, a careful revision of the concept of microglia polarization is required. The present article briefly reviews the current consensus and controversy regarding microglial polarization typing to provide supporting materials for a more objective understanding of the functional phenotype of microglia.

This study aims to perform a comprehensive multi-strategy screening of quality markers (Q-markers) by integrating serum pharmacochemistry, chromatographic fingerprinting, and network pharmacology. The objective is to apply these methodologies for the quality control of traditional Chinese medicine (TCM) compound preparations. Firstly, the UPLC-Q-Exactive Orbitrap-MS was used to conduct a comparative analysis of the aqueous extract of Di Huang Yin Zi (DHYZ), the blank group, and the dosing group. Through the Xcalibur software, 10 blood components and 17 metabolites absorbed by DHYZ were identified. Then, the HPLC acetonitrile-formic acid water gradient elution system was used for detection at 330 nm. HPLC analysis was conducted on 16 batches of samples, and 22 common peaks with a similarity greater than 0.9 were established. 8 qualitative chemical components were quantitatively analyzed. Including morroniside, loganin, echinacoside, 5-hydroxymethylfurfural, acteoside, cinnamaldehyde, polygalaxanthone III and 3,6'-disinapoyl sucrose. The sample quality was comprehensively evaluated by using cluster analysis (HCA), Principal component analysis (PCA), and Orthogonal partial least squares discriminant Analysis (OPLS-DA). The results show that the 16 batches can be divided into 4 categories, and the results of PCA and HCA are consistent. The OPLS-DA model is stable and reliable, identifying morroniside (peak 4), echinacoside (peak 9), acteoside (peak 11), and 3,6'-disinapoyl sucrose (peak 13) as key discrimination markers. Finally, using network pharmacology methods, we constructed a component-target-disease-pathway network, thereby identifying 27 components associated with the efficacy of DHYZ. By integrating the above results, 3 active ingredients, morroniside, echinacoside, and 3,6'-disinapoyl sucrose, were identified as Q-markers that can be used for the quality control of DHYZ, providing a reference for establishing a robust quality control system for DHYZ.