A CD36 transmembrane domain peptide interrupts CD36 interactions with membrane partners on macrophages and inhibits atherogenic functions

2-(2-Phenylethyl)chromone-enriched extract of Chinese agarwood (Aquilaria sinensis) inhibits atherosclerosis progression through endoplasmic reticulum stress-mediated CD36 expression in macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese agarwood, derived from the Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae), has a long history of use in Traditional Chinese Medicine for the management of cardiovascular disease. However, the specific active ingredients responsible for its impact on atherosclerosis are yet to be fully understood.

AIM OF THE STUDY

The aim of this study is to investigate the anti-atherosclerotic effectiveness of the 2-(2-phenylethyl)chromone-enriched extract derived from Chinese agarwood (CPE) through the ER stress-mediated CD36 pathway.

MATERIALS AND METHODS

To assess the effectiveness of CPE, an atherosclerotic mouse model was established using ApoE-/- mice with a high-fat diet. Then we assessed the impact of CPE on lipid accumulation in THP-1 macrophages that were exposed to oxLDL. Subsequently, the effect of CPE on the expression of CD36 and markers related to ER stress was characterized.

RESULTS

Our in vivo research confirmed that CPE effectively reduces the formation of aortic plaques in atherosclerotic ApoE-/- mice. Additionally, our in vitro study observed that CPE inhibits the uptake of oxLDL and hinders the generation of foam cells. This effect is achieved by downregulating the level of CD36 in macrophages. Furthermore, our study revealed that the increase in CD36 expression, resulting from oxLDL exposure, is governed by the activation of JNK1/2/3 signaling pathways and the initiation of ER stress.

CONCLUSION

CPE demonstrated significant efficacy to inhibit the atherosclerosis. The ER stress/P-JNK/PPARγ/CD36 signaling pathway plays critical involvement in modulating the foam cell formation in vitro and in vivo. These findings underscore the efficacy of CPE as a viable therapeutic intervention for the treatment of atherosclerosis.

Targeting Cysteine Oxidation in Thrombotic Disorders

Oxidative stress increases the risk for clinically significant thrombotic events, yet the mechanisms by which oxidants become prothrombotic are unclear. In this review, we provide an overview of cysteine reactivity and oxidation. We then highlight recent findings on cysteine oxidation events in oxidative stress-related thrombosis. Special emphasis is on the signaling pathway induced by a platelet membrane protein, CD36, in dyslipidemia, and by protein disulfide isomerase (PDI), a member of the thiol oxidoreductase family of proteins. Antioxidative and chemical biology approaches to target cysteine are discussed. Lastly, the knowledge gaps in the field are highlighted as they relate to understanding how oxidative cysteine modification might be targeted to limit thrombosis.

Border-associated macrophages promote cerebral amyloid angiopathy and cognitive impairment through vascular oxidative stress

BACKGROUND

Cerebral amyloid angiopathy (CAA) is a devastating condition common in patients with Alzheimer's disease but also observed in the general population. Vascular oxidative stress and neurovascular dysfunction have been implicated in CAA but the cellular source of reactive oxygen species (ROS) and related signaling mechanisms remain unclear. We tested the hypothesis that brain border-associated macrophages (BAM), yolk sac-derived myeloid cells closely apposed to parenchymal and leptomeningeal blood vessels, are the source of radicals through the Aβ-binding innate immunity receptor CD36, leading to neurovascular dysfunction, CAA, and cognitive impairment.

METHODS

Tg2576 mice and WT littermates were transplanted with CD36-/- or CD36+/+ bone marrow at 12-month of age and tested at 15 months. This approach enables the repopulation of perivascular and leptomeningeal compartments with CD36-/- BAM. Neurovascular function was tested in anesthetized mice equipped with a cranial window in which cerebral blood flow was monitored by laser-Doppler flowmetry. Amyloid pathology and cognitive function were also examined.

RESULTS

The increase in blood flow evoked by whisker stimulation (functional hyperemia) or by endothelial and smooth muscle vasoactivity was markedly attenuated in WT → Tg2576 chimeras but was fully restored in CD36-/- → Tg2576 chimeras, in which BAM ROS production was suppressed. CAA-associated Aβ1-40, but not Aβ1-42, was reduced in CD36-/- → Tg2576 chimeras. Similarly, CAA, but not parenchymal plaques, was reduced in CD36-/- → Tg2576 chimeras. These beneficial vascular effects were associated with cognitive improvement. Finally, CD36-/- mice were able to more efficiently clear exogenous Aβ1-40 injected into the neocortex or the striatum.

CONCLUSIONS

CD36 deletion in BAM suppresses ROS production and rescues the neurovascular dysfunction and damage induced by Aβ. CD36 deletion in BAM also reduced brain Aβ1-40 and ameliorated CAA without affecting parenchyma plaques. Lack of CD36 enhanced the vascular clearance of exogenous Aβ. Restoration of neurovascular function and attenuation of CAA resulted in a near complete rescue of cognitive function. Collectively, these data implicate brain BAM in the pathogenesis of CAA and raise the possibility that targeting BAM CD36 is beneficial in CAA and other conditions associated with vascular Aβ deposition and damage.

Border-associated macrophages promote cerebral amyloid angiopathy and cognitive impairment through vascular oxidative stress

Background: Cerebral amyloid angiopathy (CAA) is a devastating condition common in patients with Alzheimer's disease but also observed in the general population. Vascular oxidative stress and neurovascular dysfunction have been implicated in CAA but the cellular source of reactive oxygen species (ROS) and related signaling mechanisms remain unclear. We tested the hypothesis that brain border-associated macrophages (BAM), yolk sac-derived myeloid cells closely apposed to parenchymal and leptomeningeal blood vessels, are the source of radicals through the Aβ-binding innate immunity receptor CD36, leading to neurovascular dysfunction, CAA, and cognitive impairment. Methods: Tg2576 mice and WT littermates were transplanted with CD36 -/- or CD36 +/+ bone marrow at 12-month of age and tested at 15 months. This approach enables the repopulation of perivascular and leptomeningeal compartments with CD36 -/- BAM. Neurovascular function was tested in anesthetized mice equipped with a cranial window in which cerebral blood flow was monitored by laser-Doppler flowmetry. Amyloid pathology and cognitive function were also examined. Results: The increase in blood flow evoked by whisker stimulation (functional hyperemia) or by endothelial and smooth muscle vasoactivity was markedly attenuated in WT®Tg2576 chimeras but was fully restored in CD36 -/- ®Tg2576 chimeras, in which BAM ROS production was suppressed. CAA-associated Aβ 1-40 , but not Aβ 1-42 , was reduced in CD36 -/- ®Tg2576 chimeras. Similarly, CAA, but not parenchymal plaques, was reduced in CD36 -/- ®Tg2576 chimeras. These beneficial vascular effects were associated with cognitive improvement. Finally, CD36 -/- mice were able to more efficiently clear exogenous Aβ 1-40 injected into the neocortex or the striatum. Conclusions: CD36 deletion in BAM suppresses ROS production and rescues the neurovascular dysfunction and damage induced by Aβ. CD36 deletion in BAM also reduced brain Aβ 1-40 and ameliorated CAA without affecting parenchyma plaques. Lack of CD36 enhanced the vascular clearance of exogenous Aβ. Restoration of neurovascular function and attenuation of CAA resulted in a near complete rescue of cognitive function. Collectively, these data implicate CNS BAM in the pathogenesis of CAA and raise the possibility that targeting BAM CD36 is beneficial in CAA and other conditions associated with vascular Aβ deposition and damage.