IL-1β functionally attenuates ABCG2 and PDZK1 expression in HK-2 cells partially through NF-ĸB activation

PDZK1 gene transfer ameliorates lipopolysaccharide-induced cholestasis in rats by rescuing hepatic ABC transporters

Lipopolysaccharide (LPS) causes inflammatory cholestasis in sepsis. We investigated the role of PDZK1 in the repression of ABC transporters in LPS-induced cholestasis. Lentiviral gene transfer of PDZK1 to rats was conducted to explore its influence on cholestasis induced by LPS. And the effect of lentivirus-mediated shRNA targeting PDZK1 on ABC transporters in rat liver BRL-3A cells was evaluated. Lentiviral vector encoding rat PDZK1 was administered to rats by tail intravenous injection. Obviously elevated serum total bile acid level and liver biochemical markers in cholestatic rats were decreased by the Lv-PDZK1 delivery. Also, Lv-PDZK1 delivery stimulated the suppressed hepatic ABC transporters expression. In vitro, after the lentiviral vector LV3/PDZK1 shRNA transfection, no expression of PDZK1 and mild expression of ABC transporters were detected in BRL-3A cells by Western blotting. Our results indicate that the lentiviral-mediated hepatocyte PDZK1 expression ameliorates LPS-induced cholestasis in rats by rescuing hepatic ABC transporters expression.

ABCG2 Gene Expression in Non-Small Cell Lung Cancer

Background/Objectives: ATP-binding cassette subfamily G member 2 [ABCG2/breast cancer resistance protein (BCRP)] contributes to mechanisms of multidrug resistance (MDR) and is a marker of side population (SP) cells in human cancers. The primary objective of this study was to investigate the impact of ABCG2 gene expression on the non-small cell lung cancer (NSCLC) development, course of cancer disease, and patient prognosis using publicly available data. Obtained results were supplemented with assessment of ABCG2 expression in blood of NSCLC patients. Methods: The dataset of lung cancer was analyzed utilizing the TIMER 2.0, UALCAN, TNMplot, MEXPRESS, cBioPortal, MethSurv, KM Plotter, STRING, and ShinyGO 0.80 databases. Blood samples from 50 patients were assessed using the real-time PCR method. Results: The ABCG2 gene was expressed at a low level in NSCLC, and did not correlate with clinical aggressiveness of lung cancer. Higher ABCG2 expression improved overall survival, but only in LUAD. In addition, CpG sites located on the CpG island affecting the NSCLC patient's prognosis were indicated. In the case of our own laboratory results, the study did not reveal any changes in the ABCG2 expression levels in blood collected from patients at different time points during the diagnostic-therapeutic procedure. In the in silico analysis, most ABCG2 protein interactors were associated with the development of drug resistance. Conclusions: ABCG2 appears to have a particularly significant impact on the survival of patients with lung cancer and on the effect of immunotherapy related to immune cell infiltration. Presented findings may support personalized medicine strategies based on bioinformatics findings.

Promoter hypomethylated PDZK1 acts as a tumorigenic gene in glioma by interacting with AKT1

Glioma is the most frequently diagnosed primary brain tumor and typically has a poor prognosis because of malignant proliferation and invasion. It is urgent to elucidate the mechanisms driving glioma tumorigenesis and develop novel treatments to address this deadly disease. Here, we first revealed that PDZK1 is expressed at high levels in gliomas. Promoter hypomethylation may cause high expression of PDZK1 in glioma. Knockdown of PDZK1 inhibits glioma cell proliferation and invasion in vitro. Mechanistically, further investigations revealed that the loss of PDZK1 expression by siRNA inhibited the activation of the AKT/mTOR signaling pathway, leading to cell cycle arrest and apoptosis. Clinically, high expression of PDZK1 predicts a poorer prognosis for glioma patients than low expression of PDZK1. Overall, our study revealed that PDZK1 acts as a novel oncogene in glioma by binding to AKT1 and maintaining the activation of the AKT/mTOR signaling pathway. Thus, PDZK1 may be a potential therapeutic target for glioma.

Downregulation of PDZK1 by TGF-β1 promotes renal fibrosis via inducing epithelial-mesenchymal transition of renal tubular cells

Transforming growth factor-beta 1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of renal tubular cells promotes renal fibrosis and the progression of chronic kidney disease (CKD). PDZ domain-containing 1 (PDZK1) is highly expressed in renal tubular epithelial cells; however, its role in TGF-β1-induced EMT remains poorly understood. The present study showed that PDZK1 expression was extremely downregulated in fibrotic mouse kidneys and its negative correlation with TGF-β1 expression and the degree of renal fibrosis. In addition, TGF-β1 downregulated the mRNA expression of PDZK1 in a time- and concentration-dependent manner in vitro. The downregulation of PDZK1 exacerbated TGF-β1-induced EMT upon oxidative stress, while the overexpression of PDZK1 had the converse effect. Subsequent investigations demonstrated that TGF-β1 downregulated PDZK1 expression via p38 MAPK or PI3K/AKT signaling in vitro, but independently of ERK/JNK MAPK signaling. Meanwhile, inhibition of the p38/JNK MAPK or PI3K/AKT signaling using chemical inhibitors restored the PDZK1 expression, mitigated renal fibrosis, and elevated renal levels of endogenous antioxidants carnitine and ergothioneine in adenine-induced CKD mice. These findings provide the first evidence suggesting a negative correlation between PDZK1 and renal fibrosis, and identifying PDZK1 as a novel suppressor of renal fibrosis in CKD through ameliorating oxidant stress.

Intestinal uric acid excretion contributes to serum uric acid decrease during acute gout attack

OBJECTIVE

Spontaneous serum uric acid (SUA) decrease has been found in many patients during acute gout attacks, but its mechanism remains unclear.

METHODS

The spontaneous regulation of SUA during a gout attack and its possible causes were evaluated in patients with gout. The mechanism of the spontaneous SUA decrease was further studied in Caco2 cells and a monosodium urate (MSU)-induced gout model of wild-type mice and ABCG2-/- mice. The urate transport function of intestinal epithelial cells was detected by transwell culture of Caco2 cells. Expression of ATP-binding cassette super-family G member 2 (ABCG2), IL-1β and phosphoinositide 3-kinase (PI3K)/Akt was analysed using real-time PCR, western blotting, or immunofluorescence assays.

RESULTS

SUA decreased during acute gout attacks in both the gout patients and MSU-induced gouty mice. Increased serum CRP and IL-1β levels were correlated with the SUA decrease. Intestinal uric acid excretion and expression of ABCG2 were upregulated in the mice during acute gout attacks. In the ABCG2-/- mice, intestinal uric acid excretion significantly decreased during gout attacks. In an in vitro study of a transwell culture, ABCG2 and its upstream PI3K/Akt pathway were significantly upregulated in intestinal epithelial cells. However, ABCG2 expression and its associated intestinal uric acid transport were inhibited when PI3K/Akt was blocked by a PI3K inhibitor, LY294002.

CONCLUSIONS

Increased intestinal urate excretion resulted in spontaneous SUA downregulation during acute gout attacks. Inflammation-induced PI3K/Akt activation and ABCG2 expression in epithelial cells might contribute to the upregulation of intestinal uric acid excretion.

GRP/GRPR signaling pathway aggravates hyperuricemia-induced renal inflammation and fibrosis via ABCG2-dependent mechanisms

The gastrin-releasing peptide receptor (GRPR) binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. In this study, we investigated the therapeutic effect of a novel gastrin-releasing peptide receptor antagonist RH-1402 in hyperuricemia-induced kidney fibrosis and its underlying mechanisms. We conducted enzyme linked immunosorbent assay (ELISA) and immunohistochemical analyses and found that proGRP and GRPR expression levels were significantly increased in patients with hyperuricemic nephropathy (HN) and HN mice. GRPR knockdown significantly attenuated inflammatory and fibrotic responses in adenosine-treated human proximal tubule epithelial cells. GRPR knockout or GRPR conditional knockout in renal tubular epithelial cells significantly alleviated the decline in renal function and fibrosis in HN mice in vivo. RNA-seq and String database analysis revealed that GRP/GRPR promoted HN by suppressing the ABCG2/PDZK1 and increasing TGF-β/Smad3 levels by activating the NF-κB pathway. Overexpression of GRPR increased TGF-β/Smad3 levels, where as it reduced ABCG2/PDZK1 levels in adenosine-treated HK2 cells, which was reversed by the NF-κB inhibitor. Furthermore, we evaluated the therapeutic effects of the novel GRPR inhibitor RH-1402 on hyperuricaemia-induced renal injury and evaluated the inflammatory and fibrosis responses in vivo and in vitro. Pre-treatment with RH-1402 attenuated hyperuricaemia-induced renal injury, restored renal function, and suppressed renal inflammation and fibrosis. Taken together, GRPR enhances hyperuricaemia-induced tubular injury, inflammation, and renal fibrosis via ABCG2-dependent mechanisms and may serve as a promising therapeutic target for HN treatment.

The effect of lipid metabolism disorder on patients with hyperuricemia using Multi-Omics analysis

A multiomics study was conducted to investigate how lipid metabolism disorders affect the immune system in Xinjiang patients with hyperuricemia. The serum of 60 healthy individuals and 60 patients with hyperuricemia was collected. This study used LC-MS and HPLC to analyze differential lipid metabolites and enrichment pathways. It measured levels of immune factors tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), carnitine palmitoyltransferase-1 (CPT1), transforming growth factor-β1 (TGF-β1), glucose (Glu), lactic acid (LD), interleukin 10 (IL-10), and selenoprotein 1 (SEP1) using ELISA, as well as to confirm dysregulation of lipid metabolism in hyperuricemia. 33 differential lipid metabolites were significantly upregulated in patients with hyperuricemia. These lipid metabolites were involved in arachidonic acid metabolism, glycerophospholipid metabolism, linoleic acid metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, and alpha-Linolenic acid metabolism pathways. Moreover, IL-10, CPT1, IL-6, SEP1, TGF-β1, Glu, TNF-α, and LD were associated with glycerophospholipid metabolism. In patients with hyperuricemia of Han and Uyghur nationalities, along with healthy individuals, significant differences in CPT1, TGF-β1, Glu, and LD were demonstrated by ELISA (P < 0.05). Furthermore, the levels of SEP1, IL-6, TGF-β1, Glu, and LD differed considerably between groups of the same ethnicity (P < 0.05). It was found that 33 kinds of lipid metabolites were significantly different in patients with hyperuricemia, which mainly involved 5 metabolic pathways. According to the results of further studies, it is speculated that CPT1, TGF-β1, SEP1, IL-6, Glu and LD may increase fatty acid oxidation and mitochondrial oxidative phosphorylation in patients through glycerophospholipid pathway, reduce the rate of glycolysis, and other pathways to change metabolic patterns, promote different cellular functions, and thus affect the disease progression in patients with hyperuricemia.

Allisartan Isoproxil Promotes Uric Acid Excretion by Interacting with Intestinal Urate Transporters in Hyperuricemic Zebrafish (Danio rerio)

To evaluate the urate-lowering effect and potential drug targets of antihypertensive agent allisartan isoproxil (ALI) and its bioactive metabolite EXP3174, we developed an acute hyperuricemic zebrafish model using potassium oxonate and xanthine sodium salt. Losartan potassium served as the positive control (reference drug). In this model, ALI and losartan potassium exerted a greater urate-lowering effect than EXP3174 indicating that the latter is not the critical substance for elimination of uric acid. The quantitative real-time PCR showed that ALI upregulates the expression of intestinal urate transporters genes ABCG2, PDZK1, and SLC2A9 (p<0.01). Thus, we can suggest that this substance promotes uric acid excretion mainly by interacting with intestinal urate transporters.

Changes of serum uric acid level during acute gout flare and related factors

OBJECTIVE

By studying the changes of serum uric acid (SUA) in acute stage and remission stage of gouty arthritis, we aimed to explore the relationship between the changes of SUA level and free glucocorticoids and inflammatory factors.

METHODS

A prospective, longitudinal study was conducted on 50 acute gout patients in the dedicated gout clinic of the Affiliated Hospital of Qingdao University. Blood and 24-hour urine samples were collected during the acute phase and two weeks after the initial visit. Patients with acute gouty arthritis were treated primarily with colchicine and nonsteroidal anti-inflammatory drugs.

RESULTS

A total of 32 patients completed the two-week follow-up trial. SUA levels were significantly downregulated during the acute flare than after the flare (464.14 ± 90.97 vs. 527.36 ± 86.90 μmol/L, p < 0.001). The 24-hour fractional excretion of uric acid (24 h FEur) (5.54 ± 2.82% vs. 4.68 ± 2.83%, p < 0.001) and 24-hour urinary uric acid excretion (24 h Uur) (663.08 ± 249.48 μmol/L vs. 540.87 ± 263.18 μmol/L, p = 0.001) increased significantly in patients during the acute phase. The percent change in SUA was associated with those in 24 h FEur and C-reactive protein. Meanwhile, the percent change in 24 h Uur was associated with those in 24-hour urinary free cortisol, percent change in interleukin 1β and interleukin 6.

CONCLUSION

Decreased SUA level during the acute gout flare was associated with increased excretion of urinary uric acid. Inflammatory factors and bioactive free glucocorticoids may play significant roles in this process.

ABC transporters affects tumor immune microenvironment to regulate cancer immunotherapy and multidrug resistance

Multidrug resistance (MDR) is the phenomenon in which cancer cells simultaneously develop resistance to a broad spectrum of structurally and mechanistically unrelated drugs. MDR severely hinders the effective treatment of cancer and is the major cause of chemotherapy failure. ATP-binding cassette (ABC) transporters are extensively expressed in various body tissues, and actively transport endogenous and exogenous substrates through biological membranes. Overexpression of ABC transporters is frequently observed in MDR cancer cells, which promotes efflux of chemotherapeutic drugs and reduces their intracellular accumulation. Increasing evidence suggests that ABC transporters regulate tumor immune microenvironment (TIME) by transporting various cytokines, thus controlling anti-tumor immunity and sensitivity to anticancer drugs. On the other hand, the expression of various ABC transporters is regulated by cytokines and other immune signaling molecules. Targeted inhibition of ABC transporter expression or function can enhance the efficacy of immune checkpoint inhibitors by promoting anticancer immune microenvironment. This review provides an update on the recent research progress in this field.

Differential gene expression of ABCG2, SLC22A12, IL-1β, and ALPK1 in peripheral blood leukocytes of primary gout patients with hyperuricemia and their comorbidities: a case-control study

Background

The ABCG2, SLC22A12, and ALPK1 genes have been strongly associated with dysfunction of urate metabolism in patients with gout, but it is unknown how these transporters are expressed in patients with acute or chronic gout. Our objectives were to: (a) analyze the gene expression of urate transporters and of inflammation genes in peripheral blood from gout patients and controls; (b) determine whether the metabolic profile of gout patients can influence the gene expression profile and the expression of urate transporters, ABCG2 and SLC22A12, and inflammation molecules, ALPK1 and IL-1β, in peripheral blood leukocytes from gout patients; (c) compare them with their metabolic profile and the gene expression of people without gout and without hyperuricemia.

Methods

A total of 36 chronic and acute patients and 52 controls were recruited, and ABCG2, SLC22A12, IL-1β, and ALPK1 gene expression was evaluated by quantitative real-time PCR. Correlations of gene expression with clinical and laboratory parameters of patients were also analyzed.

Results

IL-1β was significantly increased in peripheral blood mononuclear cells (PBMCs) of patients compared with their polymorphonuclear leukocytes white blood cells (PMNLs, p < 0.05). A significant increase in ABCG2 and IL-1β was found in PMNLs from patients compared to controls (p < 0.05). Correlations of gene expression in patients were found with levels of serum uric acid (sUA), serum creatinine, C-reactive protein (CRP), triglycerides, body mass index (BMI), kidney disease, hypertension, and metabolic syndrome.

Conclusions

Our data suggest that leukocytes of patients respond to the presence of hyperuricemia and comorbidities, expressing ABCG2 and IL-1β genes differentially compared to normouricemic and nondisease states. Hyperuricemia, dyslipidemia, and obesity probably stimulate the differential gene expression of peripheral blood leukocytes (neutrophils and monocytes), even in an asymptomatic state.

Effect of Lactobacillus acidophilus fermentation on the composition of chlorogenic acids and anti-hyperuricemia activity of Artemisia selengensis Turcz

FASTE can relieve hyperuricemia by inhibiting the production of uric acid, alleviating oxidative stress damage and inflammation, promoting uric acid excretion and improving the abundance of intestinal flora.

Function of Uric Acid Transporters and Their Inhibitors in Hyperuricaemia

Disorders of uric acid metabolism may be associated with pathological processes in many diseases, including diabetes mellitus, cardiovascular disease, and kidney disease. These diseases can further promote uric acid accumulation in the body, leading to a vicious cycle. Preliminary studies have proven many mechanisms such as oxidative stress, lipid metabolism disorders, and rennin angiotensin axis involving in the progression of hyperuricaemia-related diseases. However, there is still lack of effective clinical treatment for hyperuricaemia. According to previous research results, NPT1, NPT4, OAT1, OAT2, OAT3, OAT4, URAT1, GLUT9, ABCG2, PDZK1, these urate transports are closely related to serum uric acid level. Targeting at urate transporters and urate-lowering drugs can enhance our understanding of hyperuricaemia and hyperuricaemia-related diseases. This review may put forward essential references or cross references to be contributed to further elucidate traditional and novel urate-lowering drugs benefits as well as provides theoretical support for the scientific research on hyperuricemia and related diseases.

BAFF signaling drives interstitial transformation of mouse renal tubular epithelial cells in a Pin1-dependent manner

Aberrant expression of B cell–activating factor belonging to TNF superfamily (BAFF) and its receptors results in abnormal biological activities in hematopoietic and non-hematopoietic cells and is closely associated with the occurrence and development of various diseases. However, the biological significance and potential mechanisms underlying BAFF signaling in renal tubular epithelial cells (RTECs) remain unknown. This study aimed to investigate the biological role of BAFF signaling in RTECs. Mice primary RTECs were applied. The proliferation status and apoptotic rates were examined by MTS assay and flow cytometry, respectively. The expression of BAFF and its receptors was analyzed via flow cytometry and sodium ion transport function, and cytokeratin-18 expression was detected through immunofluorescence staining. In addition, Pin1 was knocked down via siRNA and its expression was assessed through reverse transcription PCR. Lastly, western blotting was performed to analyze E-cadherin, ɑ-SMA, and Pin1 expression. Results suggested that BAFF-R was significantly upregulated upon IFN-γ stimulation, and enhancement of BAFF signaling promoted cell survival and reduced their apoptotic rate, while simultaneously reducing the epithelial phenotype and promoting the interstitial transformation of cells. Furthermore, Pin1 was significantly increased, along with the upregulation of BAFF signaling in the RTECs, and participated in interstitial transformation induced by BAFF signaling. Collectively, the present results elucidate the potential mechanism of loss of normal function of RTECs under long-term high dose of BAFF stimulation provides a potential therapeutic target for renal interstitial fibrosis, and underlining mechanisms of shortening of long-term outcomes of kidney allografts via augmenting of BAFF signaling.

Interleukin-37 contributes to the pathogenesis of gout by affecting PDZ domain-containing 1 protein through the nuclear factor-kappa B pathway

OBJECTIVE

Our objective was to explore the molecular pathogenesis of the onset of gout and the mechanism underlying the effect of interleukin (IL)-37 on PDZ domain-containing 1 (PDZK1) protein through the nuclear factor-κB signaling pathway.

METHODS

Real-time PCR and western blotting were used to detect expression of PDZK1 mRNA and protein, respectively, in the HK-2 cell line. The inhibitors pyrrolidine dithiocarbamate (PDTC) and wortmannin were added to HK-2 cells stimulated by IL-37, and changes in PDZK1 protein were detected by western blotting.

RESULTS

Based on our previous research, we used 10 µmol/L PDTC. We detected no significant change in PDZK1 at the mRNA level among the IL-37, PDTC+IL-37, and wortmannin+IL-37 groups. With increasing IL-37 concentration, the protein level of PDZK1 increased. After adding wortmannin, the protein level of PDZK1 increased with increasing concentration of IL-37, albeit not significantly, and the level of PDZK1 remained lower than that with IL-37 alone. After adding PDTC, the protein level of PDZK1 showed a trend to decrease with increasing concentrations of IL-37 up to 40 ng/mL. The immunofluorescence results supported the western blot results.

CONCLUSIONS

IL-37 can affect protein expression of PDZK1, but not at the translational level, in the pathogenesis of gout.

Molecular Pathophysiology of Uric Acid Homeostasis

Uric acid, the end product of purine metabolism, plays a key role in the pathogenesis of gout and other disease processes. The circulating serum uric acid concentration is governed by the relative balance of hepatic production, intestinal secretion, and renal tubular reabsorption and secretion. An elegant synergy between genome-wide association studies and transport physiology has led to the identification and characterization of the major transporters involved with urate reabsorption and secretion, in both kidney and intestine. This development, combined with continued analysis of population-level genetic data, has yielded an increasingly refined mechanistic understanding of uric acid homeostasis as well as greater understanding of the genetic and acquired influences on serum uric acid concentration. The continued delineation of novel and established regulatory pathways that regulate uric acid homeostasis promises to lead to a more complete understanding of uric acid-associated diseases and to identify new targets for treatment.

Cigarette smoke extract combined with lipopolysaccharide reduces OCTN1/2 expression in human alveolar epithelial cells in vitro and rat lung in vivo under inflammatory conditions

Organic cation transporter 1/2 (OCTN1/2) play important roles in the transport of drugs related to pulmonary inflammatory diseases. Nevertheless, the involvement of inflammation induced by cigarette smoke extract (CSE) combined with lipopolysaccharide (LPS) in the regulation of OCTN1/2 is not fully understood. In this study, CSE combined with LPS was used to establish inflammation models in vitro and in vivo. Our study found that the expression of OCTN1/2 was downregulated in rat lung in vivo and in a human alveolar cell line in vitro after treatment with CSE and LPS compared with the control group, while the expression of inflammatory factors was upregulated. After treatment with ipratropium bromide (IB) or dexamethasone (DEX), the expression of OCTN1/2 was upregulated compared with that in the CSE-LPS model group, while the expression of inflammatory factors was significantly downregulated. After administration of the NF-κB inhibitor PDTC on the basis of the inflammatory status, the expression of OCTN1/2 was upregulated in the treated group compared with the CSE-LPS model group, while the expression of phospho-p65, phospho-IκBα and inflammatory factors was significantly downregulated. We further added the NF-κB agonist HSP70 and found a result that the exact opposite of that observed with PDTC. Our findings show that CSE combined with LPS can downregulate the expression of OCTN1/2 under inflammatory conditions, and that the downregulation of OCTN1/2 expression may partially occur via the NF-κB signaling pathway.

Research Advances in the Mechanisms of Hyperuricemia-Induced Renal Injury

Uric acid is the end product of purine metabolism in humans, and its excessive accumulation leads to hyperuricemia and urate crystal deposition in tissues including joints and kidneys. Hyperuricemia is considered an independent risk factor for cardiovascular and renal diseases. Although the symptoms of hyperuricemia-induced renal injury have long been known, the pathophysiological molecular mechanisms are not completely understood. In this review, we focus on the research advances in the mechanisms of hyperuricemia-caused renal injury, primarily on oxidative stress, endothelial dysfunction, renal fibrosis, and inflammation. Furthermore, we discuss the progress in hyperuricemia management.