Vascular
dementia (VaD) is associated with cerebral hypoperfusion,
which results in long-term cognitive impairment and memory loss. Cornel
iridoid glycoside (CIG) is the major active constituent isolated from
the ripe fruit of Cornus officinalis. Previous studies have shown that CIG enhances neurological function
in VaD rats. In the present research, we attempted to clarify the
molecular processes underlying the role of CIG in neuroinflammation
in VaD. We created a chronic cerebral ischemia rat model by ligation
of the bilateral common carotid arteries (2VO) and then treated rats
with different concentrations of CIG. Comprehensive analyses revealed
that CIG ameliorated myelin integrity and neuronal loss. Furthermore,
we also found that CIG inhibited polarized microglia activation and
attenuated inflammasome-mediated production of proinflammatory cytokines
in BV2 microglia cells induced by LPS/IFN-γ and in the brains
of 2VO rats. To further elucidate the role of CIG in microglia-mediated
inflammatory response, we investigated the expression and activity
of calpain. CIG inhibited the expression and activity of calpain 1/2,
which was characterized by decreased calpastatin and spectrin αII
expression. In particular, intra- and extracellular calpain 1 levels
were reduced by CIG. However, CIG showed weak interaction with calpain
1. In addition, we found that CG administration significantly repressed
the assembly of the NOD-like receptor protein 3 (NLRP3) inflammasome,
including NLRP3, ASC, and caspase-1. In conclusion, our knowledge
of the mechanisms by which CIG regulates NLRP3/calpain signaling to
influence inflammatory responses offers further insights into potential
therapeutic strategies to treat VaD.
Improving autophagy-lysosome fusion has been considered a key method in the treatment of Alzheimer’s disease (AD). Cornel iridoid glycoside (CIG) is extracted from Cornus officinalis and has been shown to promote the clearance of tau oligomers via the autophagy pathway. However, the mechanisms of CIG on autophagy deficits are not understood. Here, we found autophagy deficit and tau aggregation in the brains of P301S tau transgenic mice and MAPT cells edited using CRISPR-Cas9 technology. CIG decreased tau aggregation and alleviated autophagic markers involving the JNK/Beclin-1 signaling pathway which demonstrated CIG that might enhance lysosome formation by upregulating ATPase Vps4A expression. Knocking down VPS4A increased autophagosome accumulation and attenuated the effect of CIG on p62. In addition, CIG had no effect on tau oligomers but still inhibited the level of tau monomer in VPS4A knockout cells. The effective component (Sweroside, SWE) of CIG attenuated tau oligomers accumulation and increased Vps4A level but not CHMP2B. SWE could not change the level of tau oligomers in VPS4A knockout cells. In conclusion, CIG suppressed autophagosome accumulation by regulating the ATPase Vps4A/JNK. SWE is a core of active factors of CIG in Vps4A regulation. These findings suggest CIG may be a potential drug in AD treatment.
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