Establishing an animal model for peritoneal catheter malfunction caused by omental wrapping using negative pressure suction: in vitro and in vivo exploration.

BACKGROUND: This study aims to establish a simplified and effective animal model of catheter malfunction caused by omental wrapped using negative pressure suction. METHOD: The peritoneal dialysis catheter outlet was linked to a negative-pressure (0-75mmHg) suction pump to intensify the negative pressure. Different negative pressures were tested for model construction in vitro. In vivo, a model of peritoneal catheter malfunction caused by omental wrapped was constructed in five beagles after catheter placement. Catheter drainage conditions and related complications were monitored before and after the model establishment. RESULTS: In the vitro experiment, the overall success rate of constructed models was 90% (36/40). The total malfunction rate was higher in 62.5 mmHg (10/10) and 75 mmHg (10/10) than in 12.5 mmHg (8/10) and 37.5 mmHg (8/10). The outflow velocity of dialysate at 62.5 mmHg was significantly lower than that at 12.5 mmHg and 37.5 mmHg, without a statistically significant difference compared to 75 mmHg. In the in vivo experiment, catheter outflow velocity increased, and residual fluid volume decreased after omental wrapped (99.6 ± 6.7 ml/min vs. 32.6 ± 4.6 ml/min at initial five minutes, p < 0.0001; 69.2 ± 16.3 ml vs. 581.0 ± 109.4 ml, p < 0.001). And the outflow velocity was finally below 2 ml/min. No severe related complications (such as infection, organ damage, or bleeding) were observed through laparoscopic examination and dialysate tests seven days post-operation. CONCLUSION: Utilizing negative pressure suction to increase negative pressure around catheter tip is a simple, safe, and effective method for establishing an animal model of omental wrapped leading to catheter malfunction.

Unlocking the potential: phenylboronic acid as a nuclear-targeting boron agent for neutron capture therapy.

It has been proposed that boron neutron capture therapy (BNCT) holds promise as a treatment modality for melanoma. However, the effectiveness of boron agents in delivery remains a critical issue to be addressed for BNCT. To this end, phenylboronic acid, which exhibits good water solubility and low cytotoxicity similar to BPA, has been investigated as a potential nuclear-targeting boron agent. The boron concentration of phenylboronic acid was found to be 74.47 ± 12.17 ng/106 B16F10 cells and 45.77 ± 5.64 ng/106 cells in the nuclei. Molecular docking experiments were conducted to investigate the binding of phenylboronic acid to importin proteins involved in nuclear transport. The potential of phenylboronic acid to serve as a desirable nucleus-delivery boron agent for neutron capture therapy in melanoma warrants further exploration.

Genetic association of lipid-lowering drugs with aortic aneurysms: a Mendelian randomization study.

AIMS: The lack of effective pharmacotherapies for aortic aneurysms (AA) is a persistent clinical challenge. Lipid metabolism plays an essential role in AA. However, the impact of lipid-lowering drugs on AA remains controversial. The study aimed to investigate the genetic association between lipid-lowering drugs and AA. METHODS AND RESULTS: Our research used publicly available data on genome-wide association studies (GWASs) and expression quantitative trait loci (eQTL) studies. Genetic instruments, specifically eQTLs related to drug-target genes and SNPs (single nucleotide polymorphisms) located near or within the drug-target loci associated with low-density lipoprotein cholesterol (LDL-C), have been served as proxies for lipid-lowering medications. Drug-Target Mendelian Randomization (MR) study is used to determine the causal association between lipid-lowering drugs and different types of AA. The MR analysis revealed that higher expression of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) was associated with increased risk of AA (OR = 1.58, 95% CI = 1.20-2.09, P = 1.20 × 10-03) and larger lumen size (aortic maximum area: OR = 1.28, 95% CI = 1.13-1.46, P = 1.48 × 10-04; aortic minimum area: OR = 1.26, 95% CI = 1.21-1.42, P = 1.78 × 10-04). PCSK9 (proprotein convertase subtilisin/kexin type 9) and CETP (cholesteryl ester transfer protein) show a suggestive relationship with AA (PCSK9: OR = 1.34, 95% CI = 1.10-1.63, P = 3.07 × 10-03; CETP: OR = 1.38, 95% CI = 1.06-1.80, P = 1.47 × 10-02). No evidence to support genetically mediated NPC1L1 (Niemann-Pick C1-Like 1) and LDLR (low-density lipoprotein cholesterol receptor) are associated with AA. CONCLUSION: This study provides causal evidence for the genetic association between lipid-lowering drugs and AA. Higher gene expression of HMGCR, PCSK9, and CETP increases AA risk. Furthermore, HMGCR inhibitors may link with smaller aortic lumen size.

KEY FINDINGS: High expression of HMGCR, PCSK9, and CETP was positively correlated with the risk of aortic aneurysms, highlighting that the corresponding lipid-lowering drugs may be preferred for preventing arterial aneurysms in high-risk individuals with dyslipidemia. We found that genetically predicted HMGCR inhibitors were positively associated with smaller aortic lumen size, which is the first time to support the causal association of gene HMGCR on the lumen size of aortic aneurysms.

This Mendelian randomization study used publicly available data involving over 1 million individuals to demonstrate the causal relationship between five target genes of LDL-C-lowering medicines and the risk of aortic aneurysms, and implied one lipid-lowering drug may link with the lumen size of aortic aneurysms.

Clinicopathological significance of tubulointerstitial CD68 macrophages in proliferative lupus nephritis.

OBJECTIVES: Tubulointerstitial macrophage plays a pathogenic role in renal damage of lupus nephritis (LN). However, the clinical and pathological role of these CD68 macrophages has not been fully described. The aim of the present study is to decipher the correlation between clinicopathological features and tubulointerstitial CD68 macrophages in 76 proliferative LN patients and further evaluate the prognostic significance of tubulointerstitial CD68 macrophages. METHODS: Tubulointerstitial CD68 macrophages were quantitated by standard histochemical staining. The correlation between the number of tubulointerstitial CD68 macrophages and clinicopathological features was analyzed by Spearman's correlation analysis. Factors potentially affecting renal prognosis were further evaluated by Cox regression analysis. RESULTS: Among the 76 proliferative LN cases, the number of CD68 macrophage infiltrates was positively correlated with serum creatinine (SCr) level, the proportion of glomeruli sclerosis and focal segmental sclerosis, tubulointerstitial inflammation, and chronicity indices, while negatively correlated with the glomerular filtration rate. During a mean follow-up period of 45 months, 5 patients (6.6%) progressed to dialysis, and 3 patents (3.9%) had a twofold increase in SCr. Multivariate Cox regression analysis showed that the number of tubulointerstitial CD68 macrophages was an independent variable associated with poor renal outcomes (HR = 1.002, P = 0.012). The optimal cutoff value of tubulointerstitial CD68 macrophages was 340/mm2 in our study with 87.5% sensitivity and 61.8% specificity to predict end-stage renal disease within 4 years. CONCLUSION: The number of tubulointerstitial CD68 macrophages was positively linked to poor prognosis of LN. Urgent immunosuppression should be considered in LN patients with abundant tubulointerstitial CD68 macrophages. Key Points • Tubulointerstitial CD68 macrophage infiltrates are positively correlated with clinicohistologic impairment in proliferative lupus nephritis. • The positive association between the number of tubulointerstitial CD68 macrophages and poor renal outcome of lupus nephritis patients were observed. • Urgent immunosuppression and monitor are required when abundant tubulointerstitial CD68 macrophage infiltrates are detected.

Therapeutic nucleus-access BNCT drug combined CD47-targeting gene editing in glioblastoma.

Glioblastoma is the most common brain primary malignant tumor with the highest mortality. Boron neutron capture therapy (BNCT) can efficiently kill cancer cells on the cellular scale, with high accuracy, short course and low side-effects, which is regarded as the most promising therapy for malignant brain tumors like glioma. As the keypoint of BNCT, all boron delivery agents currently in clinical use are beset by insufficient tumor uptake, especially in the tumor nucleus, which limits the clinical application of BNCT. In this study, nuclear targeting of boron is achieved by DOX-CB, consisting of doxorubicin (DOX) and carborane (CB) utilizing the nuclear translocation property of DOX. The nucleus of GL261 cells takes up almost three times the concentration of boron required for BNCT. To further kill glioma and inhibit recurrence, a new multifunctional nanoliposome delivery system DOX-CB@lipo-pDNA-iRGD is constructed. It combines DOX-CB with immunotherapy strategy of blocking macrophage immune checkpoint pathway CD47-SIRPα by CRISPR-Cas9 system, coupling BNCT with immunotherapy simultaneously. Compared with clinical drug Borocaptate Sodium (BSH), DOX-CB@lipo-pDNA-iRGD significantly enhances the survival rate of tumor-bearing mice, reduces tumor stemness, and improves the prognosis. The excellent curative effect of this nanoliposome delivery system provides an insight into the combined treatment of BNCT.

The Development of Boron Analysis and Imaging in Boron Neutron Capture Therapy (BNCT).

Boron neutron capture therapy (BNCT) is a selective biological targeted nuclide technique for cancer therapy. It has the following attractive features: good targeting, high effectiveness, and causes slight damage to surrounding healthy tissue compared with other traditional methods. It has been considered as one of the promising methods for the treatment of various cancers. Measuring 10B concentrations is vital for BNCT. However, the existing technology and equipment cannot satisfy the real-time and accurate measurement requirements, and more efficient methods are in demand. The development of methods and imaging applied in BNCT to help measure boron concentration is described in this review.

Retinal detachments in a patient with minimal change nephrotic syndrome: Case report and review of the literature.

Background: To report an unusual case of minimal change nephrotic syndrome with sudden bilateral retinal detachment. Case presentation: A 54-year-old woman with minimal change nephrotic syndrome presented with sudden-onset visual blurring in both eyes. Optical coherence tomography scans revealed macular schisis and extramacular intraretinal separation. A kidney biopsy confirmed the diagnosis of minimal change disease. Glucocorticoid therapy was quickly started. During remission, her vision was restored, with complete resolution of the subretinal fluid observed on optical coherence tomography. Conclusions: In minimal change nephrotic syndrome, fluid accumulation in the retina layer may occur, and gravity-induced vitreous traction on the inferior retina may cause retinal detachment. Patients should be advised to avoid large swings of the head and neck, handstands, and other activities that may increase the risk of retinal detachment. The possibility of retinal detachment should be considered when blurred vision occurs.

The role of lung ultrasonography in the assessment of overhydration in maintenance hemodialysis patients.

PURPOSE: Existed methods like biochemical markers improve the accuracy of fluid evaluation for the maintenance hemodialysis patients, but none of them has become the gold standard. This study aimed to evaluate the potential of lung ultrasonography as a useful tool for monitoring the volume status of the patients. METHODS: A total of 88 patients undergoing maintenance hemodialytic were enrolled in this prospective observational study. Patients were divided into three groups: overhydration (OH), normohydration, and hypohydration according to bioimpedance spectroscopy. Lung ultrasonography parameters, echocardiography parameters, and clinical characteristics of three groups were analyzed. After an average follow-up of 433 days, all-cause mortality among groups was compared. RESULTS: The total number of lung comets was statistically reduced in patients after dialysis (Z= -6.891, p < 0.001). This reduction was related to ΔOH (OH - ΔW (the weight gain from dry weight)) and echocardiographic parameters, which proved the relationship among the comet-tail, hydration status of body and cardiac performance. The Kappa consistency test showed that lung ultrasonography and bioelectrical spectroscopy had moderate consistency. ROC analysis showed that the best cut-point of lung comet is 13. The pre-/post-dialysis lung comet-tail, cardiac function and total body impedance with all-cause mortality was investigated. Kaplan-Meier's analysis revealed that the all-cause mortality was higher in lung congestion patients. CONCLUSIONS: This study proposes a potentially reliable lung ultrasonography method for estimating fluids overload, which also has implication value of all-cause mortality.

Mitochondrial targeted doxorubicin derivatives delivered by ROS-responsive nanocarriers to breast tumor for overcoming of multidrug resistance.

Multidrug resistance (MDR) is a serious challenge in chemotherapy and also a major threat to breast cancer treatment. As an intracellular energy factory, mitochondria provide energy for drug efflux and are deeply involved in multidrug resistance. Mitochondrial targeted delivery of doxorubicin can overcome multidrug resistance by disrupting mitochondrial function. By incorporating a reactive oxygen species (ROS)-responsive hydrophobic group into the backbone structure of hyaluronic acid - a natural ligand for the highly expressed CD44 receptor on tumor surfaces, a novel ROS-responsive and CD44-targeting nano-carriers was constructed. In this study, mitochondria-targeted triphenylphosphine modified-doxorubicin (TPP-DOX) and amphipathic ROS-responsive hyaluronic acid derivatives (HA-PBPE) were synthesized and confirmed by 1H NMR. The nanocarriers TPP-DOX @ HA-PBPE was prepared in a regular shape and particle size of approximately 200 nm. Compared to free DOX, its antitumor activity in vitro and tumor passive targeting in vivo has been enhanced. The ROS-responsive TPP-DOX@HA-PBPE nanocarriers system provide a promising strategy for the reverse of MDR and efficient delivery of doxorubicin derivatives into drug-resistant cancer cells.

Specifically Eliminating Tumor-Associated Macrophages with an Extra- and Intracellular Stepwise-Responsive Nanocarrier for Inhibiting Metastasis.

Metastasis is the primary cause of death for most cancer patients, in which tumor-associated macrophages (TAMs) are involved through several mechanisms. While hitherto there is still a lack of study on exclusive elimination of TAMs to inhibit metastasis due to the difficulties in specific targeting of TAMs, we construct an extra- and intracellular stepwise-responsive delivery system p-(aminomethyl)benzoic acid (PAMB)/doxorubicin (DOX) to achieve specific TAM depletion for the first time, thereby preventing tumor metastasis. Once accumulated into the tumor, PAMB/DOX would stepwise responsively (hypoxia and reactive oxygen species (ROS) responsively) disintegrate to expose the TAM-targeting ligand and release DOX sequentially, which depletes TAMs effectively in vivo. Owing to the inhibition of extracellular matrix (ECM) degradation, neovascularization, and tumor invasion contributed by TAM depletion, lung metastasis was successfully inhibited. Furthermore, PAMB/DOX showed efficient inhibition against tumor growth as well as spontaneous metastasis formation when combined with additional chemotherapy, representing a safe and efficient nanoplatform to modulate the adverse tumor microenvironment via TAM elimination.

The role of tumor-associated macrophages (TAMs) in tumor progression and relevant advance in targeted therapy.

Macrophages have a leading position in the tumor microenvironment (TME) which paves the way to carcinogenesis. Initially, monocytes and macrophages are recruited to the sites where the tumor develops. Under the guidance of different microenvironmental signals, macrophages would polarize into two functional phenotypes, named as classically activated macrophages (M1) and alternatively activated macrophages (M2). Contrary to the anti-tumor effect of M1, M2 exerts anti-inflammatory and tumorigenic characters. In progressive tumor, M2 tumor-associated macrophages (TAMs) are in the majority, being vital regulators reacting upon TME. This review elaborates on the role of TAMs in tumor progression. Furthermore, prospective macrophage-focused therapeutic strategies, including drugs not only in clinical trials but also at primary research stages, are summarized followed by a discussion about their clinical application values. Nanoparticulate systems with efficient drug delivery and improved antitumor effect are also summed up in this article.

Reduced Toxicity of Liposomal Nitrogen Mustard Prodrug Formulation Activated by an Intracellular ROS Feedback Mechanism in Hematological Neoplasm Models.

Nitrogen mustard (NM) is among the earliest drugs used to treat malignant tumors and it kills tumor cells by cross-linking DNA. Unfortunately, because of the short half-life and unfavorable selectivity, NM causes significant damage to normal tissues. As NM can increase the levels of reactive oxygen species (ROS) in tumor cells, a ROS-activated nitrogen mustard prodrug (NM-Pro) was synthesized and mixed with NM at a specific ratio to obtain an "NM-ROS-NM-Pro-NM" positive feedback system, which ultimately achieves a specific lethal effect on hematological neoplasms. The further encapsulation of NM/NM-Pro in liposomes allows the sustained release of the drug and prolongs the residence time in vivo. Here, we prepared stable liposomes with a uniform particle size of 170.6 ± 2.2 nm. The optimal ratio of NM to NM-Pro in this study was 2:1. The active drug NM in the NM/NM-Pro system continuously stimulated ROS production by the cells, which in turn further activated the NM-Pro to continuously generate NM. The positive feedback pathway between the NM and NM-Pro resulted in the specific death of tumor cells. Furthermore, the K562 hematological neoplasm model was utilized to evaluate the therapeutic effect of NM/NM-Pro liposomes in vivo. After encapsulation in liposomes, the targeting of tumor cells was increased approximately two times compared with that of normal cells, and NM/NM-Pro liposomes exhibited reduced toxicity, without an increase in drug activity compared to the NM/NM-Pro combination. The NM/NM-Pro delivery system exerts a positive feedback effect on ROS production in tumor cells and displays good potential for the specific killing of hematoma cells.

AIE/FRET-based versatile PEG-Pep-TPE/DOX nanoparticles for cancer therapy and real-time drug release monitoring.

On account of the biological significance of self-assembling peptides in blocking the cellular mass exchange as well as impeding the formation for actin filaments resulting in program cell death, stimuli-responsive polypeptide nanoparticles have attracted more and more attention. In this work, we successfully fabricated doxorubicin-loaded polyethylene glycol-block-peptide (FFKY)-block-tetraphenylethylene (PEG-Pep-TPE/DOX) nanoparticles, where the aggregation-induced emission luminogens (AIEgen, TPE-CHO) can become a fluorescence resonance energy transfer (FRET) pair with the entrapped antitumor drug DOX to detect the release of drugs dynamically. This is the first successful attempt to detect and quantify the change of FRET signals in A549 cells via three methods to monitor the cellular uptake of nanoprobes and intracellular drug molecule release intuitively. As we proposed here, the combination of free DOX and the self-assembling peptide could achieve the synergistic anticancer efficacy. The multifunctional PEG-Pep-TPE/DOX nanoparticles may provide a new opportunity for combination cancer therapy and real-time detection of the drug release from stimuli-responsive nanomedicine.

Intracellular Restructured Reduced Glutathione-Responsive Peptide Nanofibers for Synergetic Tumor Chemotherapy.

Self-assembled peptide nanofibers have been widely studied in cancer nanotherapeutics with their excellent biocompatibility and low toxicity of degradation products, showing the significant potential in inhibiting tumor progression. However, poor solubility prevents direct intravenous administration of nanofibers. Although water-soluble peptide precursors have been formed via the method of phosphorylation for intravenous administration, their opportunities for broad in vivo application are limited by the weak capacity of encapsulating drugs. Herein, we designed a novel restructured reduced glutathione (GSH)-responsive drug delivery system encapsulating doxorubicin for systemic administration, which achieved the intracellular restructuration from three-dimensional micelles into one-dimensional nanofibers. After a long blood circulation, micelles endocytosed by tumor cells could degrade in response to high GSH levels, achieving more release and accumulation of doxorubicin at desired sites. Further, the synergistic chemotherapy effects of self-assembled nanofibers were confirmed in both in vitro and in vivo experiments.

Remarkable Boron Delivery Of iRGD-Modified Polymeric Nanoparticles For Boron Neutron Capture Therapy.

PURPOSE: Boron neutron capture therapy (BNCT) is an emerging binary radiotherapy, which is limited for application due to the challenge of targeted delivery into tumor nowadays. Here, we propose the use of iRGD-modified polymeric nanoparticles for active targeted delivery of boron and doxorubicin (DOX) in BNCT. METHODS: 10B-enriched BSH was covalently grafted to PEG-PCCL to prepare 10B-polymer, then surface-modified with iRGD. And, DOX was physically incorporated into polymers afterwards. Characterization of prepared polymers and in vitro release profile of DOX from polymers were determined by several methods. Cellular uptake of DOX was observed by confocal microscope. Accumulation of boron in cells and tissues was analyzed by ICP-MS. Biodistribution of DOX was studied by ex vivo fluorescence imaging and quantitative measurement. Tumor vascular normalization of Endostar for promoting delivery efficiency of boron on refractory B16F10 tumor was also studied. RESULTS: The polymers were monodisperse and spheroidal in water with an average diameter of 24.97 nm, which were relatively stable at physiological pH and showed a sustained release of DOX, especially at endolysosomal pH. Enhanced cellular delivery of DOX was found in iRGD-modified polymer group. Cellular boron uptake of iRGD-modified polymers in A549 cells was remarkably raised fivefold (209.83 ng 10B/106 cells) compared with BSH. The polymers represented prolonged blood circulation, enhanced tumor accumulation of 10B against BSH, and favorable tumor:normal tissue boron concentration ratios (tumor:blood = 14.11, tumor:muscle = 19.49) in A549 tumor-bearing mice 24 hrs after injection. Both fluorescence imaging and quantitative measurement showed the highest tumor accumulation of DOX at 24 hrs after injecting of iRGD-modified polymers. Improvement of vascular integrity and reduction of vascular mimicries were found after Endostar injection, and raised tumor accumulation of boron as well. CONCLUSION: The developed nanoparticle is an inspiring candidate for the safe clinical application for BNCT.

Doxorubicin derivative loaded acetal-PEG-PCCL micelles for overcoming multidrug resistance in MCF-7/ADR cells.

Objective: This study was aimed to develop DOX-TPP loaded acetal-PEG-PCCL micelles to improve the clinical efficacy of drug resistance tumor. Significance: Chemotherapy is one of the main treatments for breast cancer but is plagued by multidrug resistance (MDR). DOX-TPP-loaded micelles can enhance the specific concentration of drugs in the tumor and improve the efficacy and overcome MDR. Methods: In this study, DOX-TPP-loaded micelles based on acetal-PEG-PCCL were prepared and their physicochemical properties were characterized. The cellular uptake and ability to induce apoptosis of the micelles was confirmed by flow cytometry in MCF-7/ADR cells. In addition, cytotoxicity of the micelles was studied in MCF-7 cells and MCF-7/ADR cells. Confocal is used to study the subcellular distribution of DOX. Free DOX-TPP or DOX-TPP-loaded acetal-PEG-PCCL micelles were administered via intravenous injection in the tail vain for the biodistribution study in vivo. Results: The diameter of micelles was about 102.4 nm and their drug-loading efficiency is 61.8%. The structural characterization was confirmed by 1H NMR. The micelles exhibited better antitumor efficacy compared to free doxorubicin in MCF-7/ADR cells by MTT assay. The apoptotic rate and the cellular uptake of micelles were significantly higher than free DOX and DOX-TPP. Micelles can efficiently deliver mitochondria-targeting DOX-TPP to tumor cells. The result of bio-distribution showed that the micelles had stronger tumor infiltration ability than free drugs. Conclusions: In this study, mitochondriotropic DOX-TPP was conjugated to the nanocarrier acetal-PEG-PCCL via ionic interaction to form a polymer, which spontaneously formed spherical micelles. The cytotoxicity and cellular uptake of the micelles are superior to free DOX and exhibit mitochondrial targeting and passive tumor targeting, indicating that they have potential prospects.

Nanocarriers as a powerful vehicle to overcome blood-brain barrier in treating neurodegenerative diseases: Focus on recent advances.

Neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington disease and amyotrophic lateral sclerosis throw a heavy burden on families and society. Related scientific researches make tardy progress. One reason is that the known pathogeny is just the tip of the iceberg. Another reason is that various physiological barriers, especially blood-brain barrier (BBB), hamper effective therapeutic substances from reaching site of action. Drugs in clinical treatment of neurodegenerative diseases are basically administered orally. And generally speaking, the brain targeting efficiency is pretty low. Nano-delivery technology brings hope for neurodegenerative diseases. The use of nanocarriers encapsulating molecules such as peptides and genomic medicine may enhance drug transport through the BBB in neurodegenerative disease and target relevant regions in the brain for regenerative processes. In this review, we discuss BBB composition and applications of nanocarriers -liposomes, nanoparticles, nanomicelles and new emerging exosomes in neurodegenerative diseases. Furthermore, the disadvantages and the potential neurotoxicity of nanocarriers according pharmacokinetics theory are also discussed.

Interactions between Macrophages and Cyst-Lining Epithelial Cells Promote Kidney Cyst Growth in Pkd1-Deficient Mice.

BACKGROUND: Autosomal-dominant polycystic kidney disease (ADPKD) is the leading inherited renal disease worldwide. The proproliferative function of macrophages is associated with late-stage cyst enlargement in mice with PKD; however, the way in which macrophages act on cyst-lining epithelial cells (CLECs) has not been well elucidated. METHODS: We generated a rapid-onset PKD mouse model by inactivating Pkd1 on postnatal day 10 (P10) and compared cell proliferation and differential gene expression in kidney tissues of the PKD mice and wild-type (WT) littermates. RESULTS: The cystic phenotype was dominant from P18. A distinct peak in cell proliferation in polycystic kidneys during P22-P30 was closely related to late-stage cyst growth. Comparisons of gene expression profiles in kidney tissues at P22 and P30 in PKD and WT mice revealed that arginine metabolism was significantly activated; 204 differentially expressed genes (DEGs), including Arg1, an arginine metabolism-associated gene, were identified in late-stage polycystic kidneys. The Arg1-encoded protein, arginase-1 (ARG1), was predominantly expressed in macrophages in a time-dependent manner. Multiple-stage macrophage depletion verified that macrophages expressing high ARG1 levels accounted for late-stage cyst enlargement, and inhibiting ARG1 activity significantly retarded cyst growth and effectively lowered the proliferative indices in polycystic kidneys. In vitro experiments revealed that macrophages stimulated CLEC proliferation, and that L-lactic acid, primarily generated by CLECs, significantly upregulated ARG1 expression and increased polyamine synthesis in macrophages. CONCLUSIONS: Interactions between macrophages and CLECs promote cyst growth. ARG1 is a key molecule involved in this process and is a potential therapeutic target to help delay ADPKD progression.