Obesity prevalence is progressively growing as living conditions rise and physical labor decreases. Obesity is most likely caused by a complex mix of changes in the dietary environment; physical activity; and socioeconomic, environmental, and genetic variables. Since 1980, the global prevalence of being overweight and obese has more than doubled, with over a third of the world’s population categorized as overweight or obese. Obesity rates have risen across all ages and sexes, regardless of geographical location, race, or financial level (Chooi et al., 2019).

Obesity-related glomerulopathy (ORG) is becoming increasingly common with the global obesity epidemic. Glomerular hypertrophy and focal segmental glomerulosclerosis (FSGS), particularly the perihilar form, are pathologic characteristics of ORG, and the degree of foot process effacement in ORG is generally less than that in primary FSGS. Obesity-induced increases in glomerular filtration rate, renal plasma flow, filtration fraction, and tubular sodium reabsorption cause the glomerulus to expand. Although most patients have stable or slowly progressing proteinuria, up to one-third suffer progressive renal failure and end-stage renal disease (D'Agati et al., 2016). Insights from Mendelian randomization and human kidney transcriptomics suggest that a putatively causal association of obesity with renal health is primarily independent of blood pressure and type 2 diabetes and reveal the signatures of obesity on the transcriptome of the human kidney (Xu et al., 2021).

BBR, as a botanical compound, is widely employed in ameliorating obesity, although no available research has been mentioned regarding its usage in ORG. To date, many previous studies have demonstrated that BBR effectively inhibits the development of obesity via modulation of the gut microbiota, intestinal permeability, gene regulation, and hepatic gluconeogenesis (Ilyas et al., 2020). The detailed potential mechanisms of BBR against obesity are summarized in Table 1 and are as follows.

First, the modulation of gut microbiota: the imbalance of intestinal flora is an important cause of obesity. BBR could reduce the exogenous antigen load in the host and elevate short-chain fatty acid levels in the intestine (Zhang et al., 2012), modulate gut microbiota, restore the gut barrier, and improve gut peptide levels (Xu J. H. et al., 2017).

Second, anti-inflammatory effects: long-term chronic inflammation exists in obesity. BBR treatment notably decreases the phosphorylation state of JNK1 in both hepatoma H4IIE cells and mouse primary hepatocytes, suggesting that improving diet-induced obesity is largely attributable to BBR’s suppression of inflammation (Guo et al., 2016). Furthermore, BBR significantly increases the CD206 + M2 adipose tissue macrophage (ATM) population while significantly reducing tumor necrosis factor-α (TNF-α), C-C motif chemokine ligand 2 (CCL2), CCL4, CCL5, and C-X-C motif chemokine receptor 4 (CXCR4) (Noh et al., 2022).

Third, mitochondrial energy metabolism is regulated. BBR significantly increases fasting-induced adipose factor (Fiaf, a key protein negatively regulated by intestinal microbes) expression in intestinal and visceral adipose tissues. BBR considerably increases AMP-activated protein kinase (AMPK) mRNA, peroxisome proliferator-activated receptor gamma (PPARG) coactivator 1-alpha (PGC1α), uncoupling protein 2 (UCP2), carnitine palmitoyl transferase 1-alpha (CPT1α), and Hadhb related mitochondrial energy metabolism (Xie et al., 2011).

Fourth, the central obesity-related pathway is regulated. By regulating the central obesity-related pathway, microinjections of BBR in the hypothalamus area of rats lower food intake and glucose rise and prevent obesity (Park et al., 2020).

Finally, there are other mechanisms. Because BBR lowers mouse weight gain and food intake with the downregulation of PPAR and upregulation of GATA binding protein 3 (GATA-3), transcription factors function in high-fat diet (HFD)-induced mice (Hu and Davies, 2010). Additionally, through the bitter-taste receptor (TAS2R) signaling pathway, BBR increases the production of glucagon-like peptide-1 (GLP-1) in vivo and ex vivo, encourages tuft cell proliferation, and secretes IL-25 in obesity (Sun et al., 2022).

IR is generally secondary to obesity or diabetes. Although it does not directly affect the kidney, its complications, such as MetS, obesity, hypertension, and diabetes, could result in a series of kidney impairments. In the case of these potential kidney injuries, it is imperative to intervene in IR from the origin. BBR is suggested to play a prominent role in attenuating IR via different signaling pathways in the cell, animal, and clinical trials involving multiple molecules, proteins, and multiple tissues. The detailed potential mechanisms of BBR against IR are summarized in Table 2 and are as follows.

First, the AMPK activity is activated. BBR appears to reduce IR in H9c2 cardiomyocytes, at least in part, by stimulating AMPK activity, as shown by BBR’s considerably enhanced AMPK activity (Chang et al., 2013). The anti-inflammatory benefits of BBR are achieved by activating AMPK-dependent autophagy in ATMs, hence reducing IR (Zhou et al., 2017). Furthermore, BBR increases the protein expression of phospho-AMP-activated protein kinase (p-AMPK) and protects against IR caused by fructose (Li et al., 2020).

Second, insulin sensitivity and insulin receptor (InsR) are increased. Preliminary findings show that suppressing fat storage and altering the adipokine composition improve insulin sensitivity in human preadipocytes and patients with MetS. BBR increases InsR mRNA and protein expression in human liver cells. Meanwhile, BBR boosts insulin sensitivity, InsR, and protein kinase C (PKC) activity in type 2 diabetes mellitus rat liver (Kong et al., 2009). BBR may reduce IR in rats with non-alcoholic fatty liver disease (NAFLD) by increasing IRS-2 mRNA and protein levels (Xing et al., 2011). In HFD-induced IR rats, BBR may ameliorate the development of IR by differentially preventing alterations of IR, IRS-1, and glucagon in β-cells, α-cells, and hepatocytes (Gu et al., 2012).

Third, BBR has anti-inflammatory effects. Inflammation also participates in the pathological process of IR. According to a meta-analysis of randomized controlled trials (RCTs) on Chinese subjects with MetS and associated illnesses, high-sensitivity C-reactive protein (hs-CRP) was strongly connected with IR (r = 0.9929, p < 0.05) (Cao and Su, 2019). BBR efficiently suppressed IL-6 and TNF-α production in palmitate (PA)-stimulated hepatocytes, indicating that BBR may increase insulin sensitivity in conjunction with its anti-inflammatory effects (Lou et al., 2011). BBR inhibited PA-induced NLRP3 inflammasome activation and caspase 1 and interleukin-1 (IL-1) release in HFD-induced IR (Zhou et al., 2017). Additionally, BBR alleviates IR in HepG2 cells via a cholinergic anti-inflammatory mechanism (Li F. et al., 2016).

Fourth, the gut microbiota is regulated. BBR improved IR in HFD-fed mice, which was connected not only with gut microbiota changes in branched-chain amino acid (BCAA) production but also with BCAA catabolism in liver and adipose tissues (Yue et al., 2019). The prevention of IR by BBR in HFD-fed rats is at least partially mediated by structural modulation of the gut microbiota, which may help alleviate inflammation by reducing the exogenous antigen load in the host and elevating short-chain fatty acid levels in the intestine (Zhang et al., 2012). BBR reversed dysbacteriosis and inhibited Toll-like receptor 4 (TLR4)/TNF-α activation, resulting in increased InsR and InsR substrate-1 expression in the liver, suggesting that BBR may reduce IR, at least in part by modulating the gut microbiota (Liu et al., 2018).

Fifth, hypoxia-inducible factor (HIF) is inhibited and could alleviate IR by inhibiting fatty acid oxidation (FAO)-mediated activation of the NLRP3 inflammasome (Li X. et al., 2021). In HFD-fed mice, BBR reduced hypoxia-inducible factor 2α (HIF-2α)-induced ceramide production and attenuated ceramide-induced IR (Xia et al., 2022). In IR adipocyte models, BBR improves insulin sensitivity, and the beneficial effects of BBR are possibly realized through the inhibition of HIF3α methylation (Wang et al., 2019).

Finally, other mechanisms are involved, such as reducing PPARG and fatty acid transferase (FAT)/CD36 (Chen et al., 2009), inhibition of cyclophilin protein (Dong et al., 2021), M1 macrophage activation (Ye et al., 2016), the leukotriene B4 (LTB4)–BLT1 axis (Gong et al., 2021), I-kappa-B kinase-β (IKκβ) (Yi et al., 2008), mitogen-activated protein (MAP) kinase kinase kinase (MEKK) 1, MAP kinase (MEK) 1/2, ERK1/2 (Li et al., 2022), nuclear transcription factor-kappa B (NF-κB) p65 (Yi et al., 2007), increased liver X receptor (LXR) α, PPARα, and sterol regulatory element-binding protein (SREBP) (Liu et al., 2010), enhancing mitochondrial architecture via sirtuin 1 (SIRT1)/optic atrophy 1 (Opa1) (Xu et al., 2022), regulating microRNA-146b/SIRT1 (Sui et al., 2021), and bone morphogenetic protein 4 (BMP4) transcription (Li G. S. et al., 2016).

Hyperglycemia in MetS is composed of either prediabetes or diabetes. The odds ratios (ORs) for isolated microalbuminuria and impaired fasting glucose were 1.58 (1.10–2.25), suggesting that prediabetes, combining impaired fasting glucose and impaired glucose tolerance, may be detrimental to the kidney. Additionally, among individuals with prediabetes, the OR for isolated decreased kidney function was 2.57 (1.31–5.06) (Markus et al., 2018). Without immediate prevention, prediabetes is susceptible to progression into diabetes. Fortunately, BBR slows the progression of prediabetes to diabetes in diabetic fatty rats by enhancing the intestinal secretion of glucagon-like peptide-2 and improving the gut microbiota (Wang et al., 2021).

A meta-analysis of observational studies showed that the overall pooled prevalence of diabetic nephropathy (DN) was 21.8% in China (Zhang X. X. et al., 2020). DN is responsible for 30%–50% of all end-stage renal disease causes. The increased filtration and total renal size of early-stage diabetes are correlated with elevations in glomerular and tubular size. The mesangial compartment of the glomerulus grows as matrix formation rises, likely as the mesangial cell population increases (Ibrahim and Hostetter, 1997).

BBR is frequently used in the prevention and control of DN due to its blood glucose lowering, anti-inflammation, anti-fibrosis, and flora adjustment effects. The comprehensive potential mechanisms of BBR against DN are summarized in Table 3 and are as follows.

First, the NF-κB pathway is inhibited. BBR decreased renal impairment in the streptozotocin (STZ)-induced DN rat model, as shown by lowering fasting blood glucose, kidney weight to body weight ratio, 24-h proteinuria, urea nitrogen (BUN), and creatinine (Cr) levels. BBR suppressed the TLR4/NF-κB pathway and decreased the systemic and renal cortex inflammatory responses in STZ-induced DN rats and high glucose (HG)-induced podocytes (Zhu L. et al., 2018). Another study revealed that under diabetic conditions, BBR lowers fibronectin (FN) expression by acting on the sphingosine 1-phosphate (S1P) 2 receptor in the mesangium, which might be related to its inhibitory action on NF-κB activation (Huang et al., 2012). A current study shows that BBR can prevent type 2 diabetes by suppressing NF-κB-driven renal inflammation and the transforming growth factor (TGF)/Smad3 signaling pathway (Sun et al., 2015).

Second, mesangial proliferation was reduced. Glomerular mesangial cell proliferation is one of the main pathological changes in DN. A current study found that Huang-Gui solid dispersion (HGSD), a novel BBR formulation, prevented DN by reducing renal mesangial matrix growth and activating autophagy, which might be linked to AMPK phosphorylation activation (Zhang M. et al., 2020). Furthermore, BBR can prevent the progression of DN, perhaps by blocking the PI3K/Akt/AS160/glucose transporter 1 (GLUT1) signaling pathway, which regulates HG-induced aberrant glomerular mesangial cell (GMC) proliferation and the cell cycle (Ni et al., 2022).

Third, BBR has anti-inflammatory effects. In the DN hamster kidney, NLRP3–Caspase-1–Gasdermin D (GSDMD) signaling was increased. BBR can diminish oxidative stress damage by modulating antioxidative Nrf2 and then NLRP3–Caspase-1–GSDMD signaling to prevent pyroptosis and antagonize DN inflammation-induced damage (Ding et al., 2021). BBR inhibited HG-induced epithelial-to-mesenchymal transition (EMT) and renal interstitial fibrosis by inhibiting the NLRP3 inflammasome, implying that BBR might be utilized as a new medication to treat tubulointerstitial fibrosis in DN (Ma et al., 2022).

Fourth, BBR has anti-fibrotic effects. Glomerular mesangial cell proliferation is one of the main pathological changes in DN. Consistently, BBR inhibits renal tubular EMT and renal interstitial fibrosis through Notch/snail pathway regulation (Yang et al., 2017). Through the Smad signaling pathway, BBR can maintain the dynamic equilibrium of TGF-β1/SnoN expression in renal tissues, hence mitigating renal dysfunction (Liu et al., 2012).

Finally, there are other mechanisms. The renoprotective effects of BBR on DN may be connected with alterations in the extracellular matrix via control of the matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) pathway in the rat kidney (Ni et al., 2015). BBR (100, 200 mg/kg) alleviated DN histopathology, which may be related to the control of β-arrestin expression, as well as intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels in the rat kidney (Tang et al., 2016).

In MetS, high blood pressure is defined as prehypertension or hypertension according to varying diagnosis criteria. A meta-analysis revealed that prehypertension showed an increased risk of chronic kidney disease (CKD) (pooled RR = 1.28) compared with the optimal BP values. Therefore, prehypertension is a potential cause of CKD (Li Y. et al., 2016). Meanwhile, hypertension and malignant hypertension can induce hypertensive kidney damage with different kidney pathological features. Secondary hypertension is commonly induced by parenchymal and renovascular diseases. Thus, hypertension and renal injury interact, ultimately cultivating a vicious cycle. Anti-hypertension is especially crucial for blood pressure-dependent kidney damage, regardless of which reason induces hypertension.

Abnormal hemodynamics, activation of the renin–angiotensin–aldosterone system (RAAS), oxidative stress, inflammation, genetic factors, and metabolic disorders contribute to hypertensive kidney damage (Fang-Ming et al., 2015). The pathological features of benign hypertension nephropathy are characterized by a thickened interlobular artery intima, stratified elastic layer, and arteriole hyalatosis, with/without media smooth muscle cell proliferation. Pathological manifestations of malignant hypertension kidney injury are malignant lesions of the arteries, including fibrinous necrosis of the arteries (acute lesions), “scallion-skin-like” changes in intimal hyperplasia of the arteries (chronic lesions), fibrinous necrosis of glomerular vascular loops, and benign lesions of the arteries (Shao-Shan et al., 2015).

BBR exerts certain beneficial effects on hypertension nephropathy. A randomized, double-blind, placebo-controlled clinical trial indicated a significant decrease in systolic blood pressure (SBP) (123 ± 7 vs. 115 ± 9 mmHg, p < 0.01), which was observed after BBR administration compared with placebo (Perez-Rubio et al., 2013). The anti-hypertension mechanisms of BBR are summarized in Table 4 and are as follows.

First, endothelial function is improved. Endothelial dysfunction is an important determinant risk factor for the development of hypertension and its complications. Hence, improving endothelial function has major clinical importance. In spontaneously hypertensive rats (SHRs) with carotid arteries, BBR lowers endothelium-dependent contractions (EDCs), most likely by activating AMPK, which then prevents endoplasmic reticulum stress and scavenges reactive oxygen species (ROS), causing cyclooxygenase-2 (COX-2) to be downregulated (Liu et al., 2015). Endothelial dysfunction and arterial stiffness are linked to abnormal alterations in circulating microparticles (MPs) and endothelial progenitor cells (EPCs) in SHRs. BBR enhanced endothelial function by preserving superior endothelium-dependent vasodilation and retained arterial elasticity by reducing aortic pulse wave velocity (aPWV) and increasing the content of arterial media elastin fiber (Zhang G. et al., 2020).

Second, there is vasodilation. By activating the large conductance calcium-activated K+ 504 channels (BKCa) in vascular smooth muscle cells (VSMCs), BBR decreased blood pressure and enhanced vasodilation in diabetic rats, suggesting that BBR could provide a combined treatment for regulating hyperglycemia and blood pressure in diabetes (Ma et al., 2017). The angiotensin-converting enzyme inhibitory impact, direct release of nitric oxide/cyclic guanosine monophosphate (NO/cGMP), and α1-adrenoreceptor antagonistic activity of BBR all contribute to its vasodilatory effect, which may explain the drop in blood pressure (Derosa et al., 2012).

Third, BBR affects antioxidants. In 2K1C renovascular hypertensive rats, chronic infusion of BBR decreased mean arterial pressure (MAP), paraventricular nucleus Fra-like activity, and plasma levels of norepinephrine (NE), as well as NADPH oxidase 2 (NOX2), NOX4, ERK1/2, and inducible nitric oxide synthase (iNOS). This finding suggests that BBR attenuates hypertension and sympathoexcitation by inhibiting the ROS/ERK1/2/iNOS pathway (Tian et al., 2019).

Finally, the gut microbiota is regulated. BBR administration dramatically reduced vascular dysfunction and pathological remodeling in Ang II-induced hypertensive mice, suggesting that the protective effect of BBR in hypertension may be attributable (at least in part) to the reduction in trimethylamine (TMA)/trimethylamine-N-oxide (TMAO) formation through gut microbiota regulation (Wang Z. et al., 2022).

However, a systematic review involving 614 participants revealed that the data from randomized trials are insufficient to prove the efficacy and safety of BBR in the treatment of hypertension as its evidence is restricted, of low quality, and ultimately inconclusive (Suadoni and Atherton, 2021).

Hyperlipidemia is frequently secondary to nephrotic syndrome, chronic renal failure, and postrenal transplant conditions. Because these disorders appear to enhance the risk of coronary heart disease, lowering blood lipids is particularly important (Grundy, 1990). Moreover, feeding cholesterol to experimental animals induced the initiation and progression of glomerular injury, and treatment of hyperlipidemic animals with lipid-lowering drugs slowed the development of glomerulosclerosis (Kamanna et al., 1998).

BBR, a natural lipid-lowering agent, is salutary in animal and clinical experiments. Scholars showed that BBR improved adipose tissue remodeling by activating Sirtuin 3 (SIRT3), which could contribute to the anti-hyperlipidemic effect (Li 2022). After 8 weeks of treatment with BBR, cholesterol was significantly decreased in a rat model of MetS (Li et al., 2015). Patients who received BBR also showed statistically significant improvements in total cholesterol (MD, −0.58; 95% CI, −0.74 to −0.41) and low-density lipoprotein (LDL) (MD, 0.52; 95% CI, −0.68 to −0.35) in antipsychotic-associated weight gain and MetS in patients with schizophrenia (Chan et al., 2022). In hyperlipidemic patients with chronic hepatitis or liver cirrhosis, BBR significantly lowered blood cholesterol, triglycerides, and LDL-cholesterol (LDL-c) (Zhao et al., 2008). The exhaustive potential hypolipidemic mechanisms of BBR are shown in Table 5 and are as follows.

First, BBR inhibits lipid synthesis in human hepatocytes through the direct and indirect activation of AMPK in peripheral tissues (notably the liver and muscles) (Brusq et al., 2006; Kim et al., 2009; Wang et al., 2016). BBR can protect the lean body mass from excessive lipid accumulation by promoting mitochondrial biogenesis and improving FAO in an AMPK/PGC-1α-dependent manner (Yao et al., 2020). BBR moderates lipid metabolism through AMPk-p38 mitogen-activated protein kinase (MAPK)-GLUT4 (Zhang et al., 2011). In addition, AMPKα1 is essential for BBR to improve glucose and lipid metabolism in HepG2 cells (Ren et al., 2020). However, prolonged activation of AMPK increases CD36 expression in hepatocytes, resulting in fatty acid uptake linked to hepatocellular lipid accumulation and fatty liver (Choi et al., 2017).

Second, BBR and its metabolites exhibit lipid-lowering effects by upregulating LDL receptor (LDLR) expression (Pisciotta et al., 2012; Zhou et al., 2014; Zhu X. et al., 2018). A study demonstrated that fatty liver could be improved by BBR administration by reversing the abnormal expression of microsomal triglyceride transfer protein (MTTP) and LDLR and inhibiting lipid synthesis (Chen et al., 2021).

Third, BBR could significantly modify the structure and composition of gut microbiota (Yang et al., 2022), and the changes in gut microbiota and metabolites are correlated with BBR improving lipid metabolism disturbances (Fang et al., 2022). Other studies demonstrated that BBR significantly inhibited the 7α-dehydroxylation conversion of cholic acid to deoxycholic acid, and the hypocholesterolemic effect of orally administered BBR was involved in its effect on modulating the turnover of bile acids and the farnesoid X receptor signaling pathway (Gu et al., 2015; Sun et al., 2017).

Fourth, BBR exhibits a dual effect on maintaining lipid homeostasis through hepatocyte nuclear factor (HNF)-4α-regulated miR-122 expression (Wei et al., 2016). BBR promotes lipid metabolism by activating the expression of miR-192, downregulating steroid regulatory element binding transcription factor 1 (SREBF1) and PPARG, increasing PPARG phosphorylation, and reducing JNK phosphorylation (Dai J. et al., 2021a; Dai J. G. et al., 2021b).

Finally, BBR alleviates lipid deposition by improving the HG-induced reduction in FAO (Rong et al., 2021). BBR can reduce steatosis by increasing ATP-binding cassette transporter A1 (ABCA1) protein levels through PKCδ to reduce the phosphorylation of serine residues in ABCA1 (Liang and Wang, 2018). Moreover, BBR represses complex I in the gut and liver and consequently inhibits lipid metabolism, leading to alleviation of obesity and fatty liver (Yu et al., 2021).

Hyperuricemia does not belong to the scope of MetS. However, hyperuricemia is induced by abnormal metabolism and is closely linked to MetS. Hence, hyperuricemia-related kidney disease is discussed under this condition. The mechanisms of hyperuricemia-related kidney disease involve RAAS activation, direct damage to uric acid (UA) crystals, and inflammation. The pathological feature of hyperuricemia-related kidney disease is characterized by tubule-interstitial injury. BBR exerts antihyperuricemic and nephroprotective effects in hyperuricemic kidney disease (Li X. et al., 2021). The mechanisms of BBR in hyperuricemia and related kidney disease are listed below.

First, BBR lowers UA by inhibiting UA biosynthesis and promoting UA excretion. BBR suppresses the expression of xanthine oxidase (XOD), urate transporter 1 (URAT1), and glucose transporter 9 (GLUT9) to lower UA (Shan et al., 2022). In addition, BBR effectively reduced serum UA levels in hyperuricemic rats by increasing urine uric acid levels and urate fractional excretion.

Second, BBR has anti-inflammatory effects. Inflammation is involved in hyperuricemia-related kidney injury. BBR drastically reduced the levels of UA, BUN, and Cr in a mouse model of hyperuricemia created by potassium oxonate and hypoxanthine, as well as kidney injury. BBR inhibits the activation of the NLRP3 inflammasome and decreases TNF-α (Shan et al., 2022), IL-1β (Liu et al., 2016), and IL-18 levels, as well as NLRP3, ASC, caspase-1, and URAT1 expression (Li Q. et al., 2021).

Finally, the gut microbiota is regulated. Subsequently, 16S rRNA sequencing data showed that BBR enriched the abundance of Coprococcus, Bacteroides, Akkermansia, and Prevotella in potassium oxonate-induced hyperuricemia, clarifying that BBR ameliorates hyperuricemia by modulating the gut microbiota (Shan et al., 2022).