The morbidity and mortality of diabetic cardiomyopathy are high worldwide. Although new therapeutic methods are constantly being updated, they still cannot effectively stop the development of the disease. Traditional Chinese medicine (TCM) has the advantages of multi-component and multi-targets, which can comprehensively regulate multiple mechanisms of DCM occurrence and development, fully reflecting the holistic concept of TCM. In this study, we systematically and thoroughly analyzed the blood-entry components of QGQXM and its mechanism of treating DCM by combining serum pharmacology, serum medicinal chemistry, and network pharmacology. We validated them in vivo by constructing a rat model of DCM. It provides the theoretical basis and data support for QGQXM to treat DCM. Researchers found that QGQXM could improve the cardiac function of DCM rats, improve the degree of cardiomyocyte injury and fibrosis, inhibit apoptosis by regulating the PI3K-Akt signaling pathway, and play a protective role for the myocardium of DCM rats.
Ultra performance liquid chromatography mass spectrometry (UPLC-Q/TOF-MS) analysis can accurately identify the chemical constituents in TCM and serum, and the results are more objective and accurate compared with the TCM constituents database, providing scientific data support for mechanism analysis. The mass spectrometry results showed that 26 prototypical components were introduced into the blood, mainly azurin, soybean flavonoids, epimedium glycosides, baicalin, scopolamine, etc. The results of mass spectrometry showed 26 prototypical components in the blood. These components acted on different mechanisms to exert anti-DCM effects. For example, azurin inhibits glutamate-induced reactive oxygen species expression, apoptosis, and attenuates mitochondrial damage in HT3 cells [26]. Soy flavonoids can improve hyperglycemia, insulin resistance, and inflammation, and reduce necrosis and fibrosis of cardiac tissues [27, 28]. Icariin inhibits cardiomyocyte apoptosis and cardiac remodeling [29, 30]. Baicalin prevents insulin resistance, metabolic dysfunction, cardiac fibrosis, and heart failure [31, 32]. Scopolamine improves insulin resistance and promotes insulin secretion [33]. Accordingly, we conducted further studies to explore the potential targets and pathways of these components for the treatment of DCM through network pharmacology to provide scientific data to support our further research.
Enrichment analysis showed that there are a large number of signaling pathways that may be involved in QGQXM for the treatment of DCM. The PI3K-Akt signaling pathway is not only the topmost among the pathways related to DCM, but also the key targets in the pathway, such as AKT1 and PIK3CA, are also the core targets in the PPI network. Therefore, we took the PI3K-Akt signaling pathway as a target for validation. The PI3K-Akt signaling pathway can regulate various cellular processes, which are closely related to cell proliferation, growth, metastasis, and apoptosis [33]. The PI3K-Akt signaling pathway has been found to play a cardioprotective role in cardiomyocytes by inhibiting apoptosis [34, 35]. PI3K, fully known as phosphatidylinositol 3-kinase, has three different types [36], of which only class I can act as lipid phosphorylator upon upstream signaling stimulation [37]. PI3K (class I) is a heterodimer consisting of the catalytic subunit P110 and regulatory subunit P85 [38]. Activation of PI3K is initiated by binding extracellular growth factors to transmembrane receptor tyrosine kinases (RTKs). When the ligand binds to the receptor, the RTK is activated and recruits PI3K at the lipid membrane. The catalytic subunit P85 binds to the RTK, releasing the catalytic subunit P110, which completes the phosphorylation of PI3K [39]. Activated PI3K anchors to the lipid membrane and catalyzes the phosphorylation of Phosphatidylinositol 4,5-bisphosphate (PIP2) to Phosphatidylinositol 3,4,5-triphosphate (PIP3). PIP3 recruits AKT, identical to mTOR complex PIP3 recruits AKT and, together with mTOR complex 2 (mTORC2), fully activates AKT [40]. Once phosphorylated, AKT detaches from the lipid membrane, migrates to the cytoplasm and nucleus, and binds to downstream target proteins located in the cytoplasm and nucleus, such as Bcl-2, FOXO, IKKα, and MDM2, thereby promoting cell survival, proliferation, growth, and resistance to apoptosis [41]. Bcl-2 family proteins regulate mitochondrial membrane permeability and are significant regulators of mitochondrial apoptosis [42]. This family of proteins consists of two functionally opposite subgroups, the anti-apoptotic members represented by BCL-2 and BCL-XL, and the pro-apoptotic members represented by BAX and BAK [43]. Among them, BCL-2 is the founding member of the family and plays a crucial role in apoptosis. caspase-9 is the initiator and effector of apoptosis and plays an important regulatory role in apoptosis [44]. Akt inhibits the pro-apoptotic members of the Bcl-2 family, such as Bad, Bax, and caspase-9, and upregulates the anti-apoptotic members of Bcl-2 and Bcl -xl and other anti-apoptotic proteins expression, and plays a survival role by regulating the balance between anti-apoptotic proteins (Bcl-2 and Bcl-XL) and pro-apoptotic proteins (Bax) [44, 45]. Therefore, we examined the protein expression levels of P-PI3K, P-AKT, BCL-2, and caspase9 by Western blot, and the results showed that the expression of P-PI3K, P-AKT, and BCL-2 was significantly increased in the myocardial tissues of QGQXM-intervened rats, whereas the expression of caspase9 was significantly decreased considerably, which was consistent with the results of a previous study. This suggests that QGQXM can resist apoptosis through the PI3K/AKT signaling pathway, which may be a potential mechanism for its anti-DCM effect. In addition, the results of network pharmacological analysis showed that QGQXM could also resist DCM by regulating HIF-1, MAPK, mTOR, Insulin, Apoptosis, and other signaling pathways, which reflected the advantages of multi-target and multi-pathway regulation of QGQXM.
Apoptosis is a form of programmed cell death that is present in a variety of pathological processes. Numerous studies have demonstrated the presence of apoptosis in the pathogenesis of DCM [46]. A prolonged hyperglycemic environment induces apoptosis in cardiomyocytes, which irreversibly causes a reduction in cardiomyocytes, which in turn reduces myocardial diastolic-contractile function and ultimately leads to cardiac remodeling [47]. Inhibition of apoptosis has therefore become an essential target for DCM therapy. Analysis of the composition of QGQXM showed that various components can exert the effect of inhibiting apoptosis including epimedoside, baicalin, and dulcitin. Icariin, the main active ingredient of the traditional Chinese medicine Epimedium, is a flavonoid that is anti-apoptotic, anti-inflammatory, hypolipidemic, and anti-oxidative stress [48]. Baicalin is one of the main active components of the traditional Chinese medicine Scutellaria baicalensis, which has been shown to alleviate chronic inflammation, lipid metabolism disorders, apoptosis, and oxidative stress [49]. Azaleatin is also a flavonoid with a wide range of pharmacological effects, inhibiting glutamate-induced reactive oxygen species expression, apoptosis, and mitochondrial damage in HT3 cells [26]. Puerarin can reduce CSE-induced apoptosis in human bronchial epithelial cells by modulating the PI3K/Akt/mTOR signaling pathway [50].
To verify the effect of QGQXM on PI3K-Akt signaling pathway-mediated cardiomyocyte apoptosis, we constructed a DCM rat model and demonstrated the model by cardiac ultrasound, and fasting blood glucose. The experimental results showed that QGQXM could ameliorate cardiomyocyte injury caused by DCM, reduce the degree of myocardial fibrosis, and improve cardiac function. Western blot results showed that the expression of p-PI3K, p-AKT, and Bcl-2 was increased in the QGQXM group. The expression of caspase-9 was decreased, suggesting that QGQXM could activate the PI3K-Akt signaling pathway, increase the expression of Bcl-2, a downstream anti-apoptotic factor, as well as down-regulate the expression of the pro-apoptotic protein caspase-9, exerting an anti-DCM effect by inhibiting cardiomyocyte apoptosis. This is consistent with previous findings.
The present study also has some limitations. In the mass spectrometry part, we only analyzed the prototypical components in the blood, and further studies are still needed for metabolizing the herbal components after entering the blood. In addition, only in vivo experiments in rats were conducted in this study, and in the future, well-established clinical trials are needed to verify its therapeutic effects.