Diabetes mellitus is a chronic degenerative metabolic disease caused by insulin resistance and islet β-cell dysfunction (Wu et al., 2014). In 2019, approximately 463 million adults (20–79 years) were living with diabetes (Saeedi et al., 2019). Over 90% of all diabetes mellitus are type 2 diabetes mellitus (T2DM). Insufficient insulin production from beta cells during insulin resistance is considered to be the cause of T2DM (Ahrén, 2005).

Acarbose is an anti-diabetic drug used to treat T2DM, which is an oligosaccharide that reversibly inhibits intestinal α-glucosidase enzymes and is responsible for digesting complex carbohydrates and disaccharides to absorb monosaccharides (Hillebrand et al., 1979; Ibrahim et al., 2018). Acarbose has competitive inhibitory activities toward intestinal maltase, sucrase, dextrinase and glycoside hydrolases, including pancreatic alpha-amylase and alpha-glucosidase in the brush border of the small intestines, and thereby delays carbohydrate absorption and controls postprandial hyperglycemia (Wehmeier and Piepersberg, 2004). The digestion rate of complex carbohydrates reduces as these enzyme systems have been inhibited. Since the carbohydrates are not broken down into glucose, less glucose is absorbed (Scheen, 1998). However, since T2DM becomes more prevalent worldwide, the demand for acarbose increases rapidly. Acarbose is produced in large-scale fermentation by Actinoplanes sp. SE50/110, which was obtained from rounds of mutagenesis and selection. Recently, comparative genome, transcriptome, and proteome analyses have provided system-level understanding of Actinoplanes sp. SE50/110 and insights into the mechanisms of acarbose overproduction (Wendler et al., 2016; Xie et al., 2019). A highly efficient genetic manipulation system was established for Actinoplanes sp. SE50/110 and was used to delete melC2 (a tyrosinase gene) and treY (a maltooligosyltrehalose synthase gene), which eliminated the formation of eumelanin and the by-product component C, resulting in a 35% increase of acarbose titer (Gren et al., 2016; Zhao et al., 2017). Additionally, in the latest research, strategies were implemented by minimizing the flux to the shunt products and maximizing the supply of the amino-deoxyhexose moiety, which increased the acarbose titer to 7.4 g/L (Zhao et al., 2020). Moreover, the effect of different saccharides on acarbose production by Actinoplanes has been studied and the transcriptome analysis revealed molecular signature of saccharide impact on acarbose biosynthesis (Weng et al., 2020, 2021). Acarbose also showed positive effects on diabetes-associated hyperlipidemia and decreased various blood lipid levels (Kado et al., 1998; Ji, 2017). Furthermore, the benefits in lipid profile associated with acarbose therapy were considered to be independent of glycemic control (Kawamura et al., 1998).

The beneficial effects of acarbose on diabetes have been confirmed by many studies (Hanefeld, 2007; Wei and Xu, 2019). However, few studies reported the global genetic effect of acarbose on kidneys, which suffers a lot from the side effects of various drugs. In this study, systematic bioinformatics analyses for a microarray dataset, GSE59913, have been performed to identify key differential genes, pathways, modules, and protein-protein interactions (PPIs) that may be critical for changes in multiple physiological activities in the kidney of rats treated with acarbose. This study uncovered 130 significant differential genes in acarbose-treated rat kidney samples. Lipid metabolism pathways were considerably enriched. Results suggested that acarbose may be an ideal drug candidate for chronic kidney disease (CKD) patients, because it can not only protect the kidney, but also relieve the complications caused by CKD.

In this study, DEGs between samples of Acarbose and Water groups were identified by comparative analysis. Analyses of PCA, GO, KEGG, PPI network, and interrelation between pathways were conducted. In total, 44 significantly up-regulated and 86 significantly down-regulated genes from GSE59913 were presented. Bioinformatics analyses were conducted based on these DEGs.

Firstly, among the pathway enrichment analyses, cell component enrichment (GO) analysis showed that the DEGs were mainly concerned about lipoproteins, which was consistent with the previous studies that acarbose may contribute to the changes in blood lipoprotein composition (Festa et al., 1999; Reddy et al., 2010; Hedrington and Davis, 2019). Up to 97% of patients with diabetes are dyslipidemic because the flux of free fatty acids increases during hyperglycemia, which also contributes to the formation of atherosclerosis (Festa et al., 1999; Reddy et al., 2010). Previous research investigated the influences of acarbose on postprandial lipid metabolism and found that the lipoprotein remnants at acute phase and acute post-prandial increase of triglycerides were ameliorated by the drug (Hedrington and Davis, 2019). According to the results of cell component enrichment analyses (Table 1), the effects of postprandial lipid metabolism are related to the regulation of lipoproteins, including chylomicron, high-density lipoprotein particle, etc., which will be discussed further below. Secondly, molecular function (GO) enrichment analyses showed that DEGs mainly influence protein binding. Lipid binding and phosphatidylcholine-sterol O-acyltransferase activator activity were also affected, showing the effect on the blood and the lipids in it, which will be discussed in more details with the networks of DEGs. Thirdly, biological process (GO) enrichment analyses showed that DEGs were mainly included in the regulation of transport, response to oxygen-containing compound and response to the endogenous stimulus. Acarbose has been shown to down-regulate oxidative stress and platelet activation and may therefore have potential cardioprotective functions (Santilli et al., 2010). The results of the analyses further supported that acarbose did have a positive effect on oxidative stress in the body.

The current study analyzed the network of DEGs and the interrelation of pathways (Figure 2). Bradykinin is a peptide that causes vasodilation and therefore reduces blood pressure (Dendorfer et al., 2001). As a hormone receptor module, Module A shows that acarbose affects blood pressure by the regulation of bradykinin receptor B1 (Bdkrb1). Additionally, 5-hydroxytryptamine receptor 2C (Htr2c) and hypocretin receptor 2 (Hcrtr2) were reported to participate in the regulation of intestinal movements and lipid metabolism, respectively (Berger et al., 2009; Skrzypski et al., 2011). Module B is the lipoprotein module, including several kinds of apolipoprotein, fatty acid binding protein and lecithin cholesterol acyltransferase. Blood lipids are mainly fatty acids and cholesterol, which can be carried in the blood stream by plasma lipoprotein particles (Shepherd et al., 1987). Acarbose has shown beneficial effects on hyperlipidemia caused by diabetes and decreases in free fatty acids and cholesterol levels (Patel, 2015), which result from the regulation of fatty acid binding protein and lecithin cholesterol acyltransferase according to Module B. Moreover, Hub Gene Analyses also showed a similar result to Module B, which further confirms the role of acarbose in blood lipids (Supplementary Table 2). Studies have shown the relationship between these two proteins and their corresponding lipids, but the mechanism of the actions between these two proteins and acarbose still remain unresolved, and further research should be performed to better explain how acarbose affects blood lipids (Yu et al., 2017). In addition, the effects related to kidney diseases also need to be noted, because renal dysfunction is related to many disorders in lipoprotein metabolism, leading to dyslipidemia and accumulation of atherosclerotic particles (Vaziri, 2014). Moreover, lecithin-cholesterol acyl-transferase (LCAT) can be observed in both Module B and hub genes, and its impact on chronic kidney disease (CKD) needs attention. LCAT deficiency is reported to contribute to diminished HDL cholesterol content and impaired HDL maturation in advanced CKD patients, which further increases oxidative stress and cardiovascular mortality in patients with CKD (Moradi et al., 2009; Ribeiro et al., 2012). However, acarbose has been shown to increase the level of HDL cholesterol, and our result suggests that this may work through effects on LCAT, and therefore may help improve physical conditions in CKD patients (Monami et al., 2012). Previous studies have shown that acarbose can protect kidney function by reducing the kidney’s filtered ammonia and nitrogen load (Evenepoel et al., 2006). Current research shows that acarbose may be an ideal drug candidate for CKD patients, because it not only protects the kidney, but also may relieve the complications caused by CKD.

Differentially expressed genes showed enrichment in lipoprotein particle, regulation of fatty acid metabolic process, peptide hormone binding and steroid hormone biosynthesis, which have been discussed before. However, other kinds of enrichment need more discussion. Solute: cation symporter activity, ATP synthesis coupled electron transport and response to mineralocorticoid related events can be seen in Figure 3, which indicates that acarbose affects a series of events about electrolytes. Acarbose may cause abnormal levels of potassium and sodium, and remain a risk of electrolyte disturbances (Khatoon and Najam, 2012). Enrichment of DEGs showed that Na⁺-K⁺-ATPase might play an important role, while mineralocorticoids also take part in this progress, because they influence electrolyte balance and fluid balance (Feraco et al., 2019). As the mineralocorticoids are produced in the adrenal cortex, some progresses about these tissues were also influenced (Table 1). Electrolyte imbalances should be considered as this may cause kidney damage, so that both ATPase and mineralocorticoids should be included into observation. Moreover, Ca²⁺, as a part of electrolyte, should also be monitored because T-tubule has been included in the DEGs enrichment, which is studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases, and Beta adrenoceptors (Hong and Shaw, 2017).

In this study, comprehensive bioinformatics analyses of gene expression profiles of Acarbose samples compared with Water samples in the R. norvegicus kidney were performed, and key genes and pathways were identified. This study revealed that the effect of acarbose on blood sugar control was mainly through the regulation of lipid metabolism and electrolytes, which was consistent with the previous studies. This finding can reveal a series of targets for further research of molecular mechanisms. Also, new insights into acarbose as an ideal drug for CKD patients had been presented, but the possibility of kidney damage from electrolyte imbalances also needs to be treated with caution. However, this study mainly focused on bioinformatic analysis of differential genes and pathways, corroborative bench work is still necessary to confirm the proposed regulation network.

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/Supplementary Material.

C-YW: data analysis, validation, writing-original draft, and funding acquisition. M-HZ: investigation, methodology, and writing original draft. K-LD: manuscript revision, writing-reviewing, and editing. Z-YM: methodology and data validation. Y-SW: writing-reviewing and editing. Y-GZ: conceptualization and resources. Z-QL: resources, writing-reviewing, and editing. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.