Red blood cell β-adrenergic receptors contribute to diet-induced energy expenditure by increasing O2 supply

DIA-based serum proteomics revealed the protective effect of modified siwu decoction against hypobaric hypoxia

ETHNOPHARMACOLOGICAL RELEVANCE

Siwu decoction (SWD) is a common traditional formula for nourishing blood, and its derived formulas are also widely used in traditional Chinese medicine (TCM) clinic. However, the protective effects of SWD and its derived formulas on blood deficiency and blood stasis caused by rushing to the plateau are rarely reported, and the underlying mechanism has not been fully elucidated.

AIM OF THE STUDY

This study explores the pharmacological effects and mechanisms of modified siwu decoction (MSWD) adding Persicae Semans (Prunus persica (L.) Batsch) and Carthami Flos (Carthamus tinctorius L.) against hypobaric hypoxia (HH). The acute toxicity of MSWD was also evaluated to further validate the potential of MSWD as a therapeutic candidate for HH.

MATERIALS AND METHODS

Hypoxic models of C57BL/6 J and KM male mice were used to evaluate the pharmacological effect of MSWD. 2 μL serum sample of C57BL/6 J mice was digested into peptide mixtures and analyzed with DIA mode on an Orbitrap Fusion Lumos mass spectrometer after LC separation. The peptide and protein identifications were limited to a 1% FDR. Screening of differential expressed proteins, correlation analysis, hierarchical clustering analysis, principal components analysis and Mfuzz analysis were all performed by R packages. The protein-protein interaction network was analyzed using the STRING website and constructed with Cytoscape software.

RESULTS

MSWD showed a protective effect against acute hypoxia exposure through increasing the number of red blood cells and improving hemodynamics indexes in mice. Meanwhile, the biochemical results showed that MSWD could reduce the inflammation and oxidative stress, reduce the content of organ injury biomarkers and significantly improve the high-intensity exercise ability of mice. Subsequently, serum DIA proteomic results revealed significant changes in proteomic characteristics after MSWD intervention. Specifically, proteins related to oxidative stress and ubiquitin-proteasome system, such as Sod1, Gstp1, Vcp and Usp14, were down-regulated after MSWD intervention, suggesting that the protective effect of MSWD involved the reduction of oxidative stress and energy expenditure. MSWD also intervened in energy metabolism and lipid metabolism processes by altering the expression levels of Eno1, Sphk1 and Apoa1 to ameliorate hypoxia-induced disorders. At the same time, MSWD acute toxicity test showed no obvious toxicity.

CONCLUSIONS

MSWD has a good protective effect against HH by ameliorating hypoxia-induced disorders of energy and lipid metabolism, supporting MSWD as a safe drug candidate for the prevention and treatment of acute hypoxia fatigue.

Essential role of systemic iron mobilization and redistribution for adaptive thermogenesis through HIF2-α/hepcidin axis

Iron is an essential biometal, but is toxic if it exists in excess. Therefore, iron content is tightly regulated at cellular and systemic levels to meet metabolic demands but to avoid toxicity. We have recently reported that adaptive thermogenesis, a critical metabolic pathway to maintain whole-body energy homeostasis, is an iron-demanding process for rapid biogenesis of mitochondria. However, little information is available on iron mobilization from storage sites to thermogenic fat. This study aimed to determine the iron-regulatory network that underlies beige adipogenesis. We hypothesized that thermogenic stimulus initiates the signaling interplay between adipocyte iron demands and systemic iron liberation, resulting in iron redistribution into beige fat. To test this hypothesis, we induced reversible activation of beige adipogenesis in C57BL/6 mice by administering a β3-adrenoreceptor agonist CL 316,243 (CL). Our results revealed that CL stimulation induced the iron-regulatory protein-mediated iron import into adipocytes, suppressed hepcidin transcription, and mobilized iron from the spleen. Mechanistically, CL stimulation induced an acute activation of hypoxia-inducible factor 2-α (HIF2-α), erythropoietin production, and splenic erythroid maturation, leading to hepcidin suppression. Disruption of systemic iron homeostasis by pharmacological HIF2-α inhibitor PT2385 or exogenous administration of hepcidin-25 significantly impaired beige fat development. Our findings suggest that securing iron availability via coordinated interplay between renal hypoxia and hepcidin down-regulation is a fundamental mechanism to activate adaptive thermogenesis. It also provides an insight into the effects of adaptive thermogenesis on systemic iron mobilization and redistribution.

Molecular Interactions between Erythrocytes and the Endocrine System

Hormones are secreted by the endocrine glands and reach their targets after circulating in the blood. Many studies have documented that erythrocytes can bind hormones, and possible interactions have been reported. Erythrocytes are responsive to signaling initiated after binding of epinephrine, norepinephrine, estrogen, progesterone, thyroid hormones, parathyroid hormone, and angiotensin. Signaling results in regulation of cellular metabolism and membrane fluidity. In addition, erythrocytes are circulating pools for dopamine, thyroid hormones, cortisol, and aldosterone. Erythrocyte function and structure are regulated by endocrine signals, while erythrocytes are important constituents for the transport of hormones in the body.

Red blood cells as an efficient in vitro model for evaluating the efficacy of metallic nanoparticles

Blood and the linings of blood vessels may be regarded as a fifth tissue type. The human body contains 5 × 10⁹ red blood cells (RBCs) per ml, a total of 2.5 × 10¹³ cells in the 5 l of blood present in the body. With an average lifetime of 125 days, human RBCs are destroyed by leukocytes in the spleen and liver. Nowadays red blood cells are extensively used to study various metabolic functions. Nanoparticles (NP) are being widely accepted for drug delivery system. This review summarizes the red blood cells, NPs and their characteristics on the basis of the RBC components along with drug delivery systems through RBCs. Further, we also discussed that how erythrocytes can be used as an efficient in vitro model for evaluating the efficacy of various nanocomposite materials.