Evaluation of Perirenal Fat as a Predictor of cT1a Renal Cortical Neoplasm Histopathology and Surgical Outcomes

Vitamin D is involved in the effects of the intestinal flora and its related metabolite TMAO on perirenal fat and kidneys in mice with DKD

BACKGROUND

Vitamin D was shown to directly exert a protective effect on diabetic kidney disease (DKD) in our previous study. However, whether it has an effect on perirenal adipose tissue (PRAT) or the intestinal flora and its metabolites (trimethylamine N-oxide, TMAO) is unclear.

METHODS

DKD mice were received different concentrations of 1,25-(OH)2D3 for 2 weeks. Serum TNF-α levels and TMAO levels were detected. 16S rRNA sequencing was used to analyze gut microbiota. qPCR was used to detect the expression of TLR4, NF-Κb, PGC1α, and UCP-1 in kidney and adipose tissue. Histological changes in kidney and perirenal adipose tissue were observed using HE, PAS, Masson and oil red staining. Immunofluorescence and immunohistochemistry were used to detect the expression of VDR, PGC1α, podocin, and UCP-1 in kidney and adipose tissue. Electron microscopy was used to observe the pathological changes in the kidney. VDR knockout mice were constructed to observe the changes in the gut and adipose tissue, and immunofluorescence and immunohistochemistry were used to detect the expression of UCP-1 and collagen IV in the kidney.

RESULTS

1,25-(OH)2D3 could improve the dysbiosis of the intestinal flora of mice with DKD, increase the abundance of beneficial bacteria, decrease the abundance of harmful bacteria, reduce the pathological changes in the kidney, reduce fat infiltration, and downregulate the expression of TLR4 and NF-κB in kidneys. The serum TMAO concentration in mice with DKD was significantly higher than that of the control group, and was significantly positively correlated with the urine ACR. In addition, vitamin D stimulated the expression of the surface markers PGC1α, UCP-1 and VDR in the PRAT in DKD mice, and TMAO downregulated the expression of PRAT and renal VDR.

CONCLUSIONS

The protective effect of 1,25-(OH)2D3 in DKD mice may affect the intestinal flora and its related metabolite TMAO on perirenal fat and kidneys.

A Review of the Paradigmatic Role of Adipose Tissue in Renal Cancer: Fat Measurement and Tumor Behavior Features

(1) Background: Renal-cell carcinoma (RCC) incidence has been steadily rising, with obesity identified as a potential risk factor. However, the relationship between obesity and RCC prognosis remains unclear. This systematic review aims to investigate the impact of different adipose tissue measurements on RCC behavior and prognosis. (2) Methods: A search of MEDLINE databases identified 20 eligible studies focusing on various fat measurements, including visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), perirenal adipose tissue (PRAT), and the Mayo adhesive probability (MAP) score. (3) Results: The review revealed conflicting findings regarding the association between adipose tissue measurements and RCC outcomes. While some studies suggested a protective role of certain fat deposits, particularly VAT, against disease progression and mortality, others reported contradictory results across different adipose metrics and RCC subtypes. (4) Conclusions: Methodological variations and limitations, such as retrospective designs and sample size constraints, pose challenges to standardization and generalizability. Further research is needed to understand these associations better and establish standardized approaches for adiposity assessment in RCC patients, which could inform clinical practice and therapeutic decision-making.

High perirenal fat thickness predicts a greater risk of recurrence in Chinese patients with unilateral nephrolithiasis

INTRODUCTION

The aim of this study was to evaluate the association between recurrence-free survival (RFS) and perirenal fat thickness (PFT) in a cohort of Chinese population with unilateral nephrolithiasis.

METHODS

We retrospectively reviewed the medical records of 81 patients with unilateral nephrolithiasis in our center from January 2019 to June 2019. PFT measured on computed tomography (CT) scans was evaluated. Kaplan-Meier curves and log-rank tests were used to assess significant differences in RSF between high-PFT and low-PFT groups within sexes. Univariable and multivariable Cox regression analyses were used to evaluate the potential risk factors for renal stone recurrence.

RESULTS

High PFT was significantly associated with high BMI and hyperlipidemia (p = .003 and.047, respectively). The PFT of stone-bearing kidney was significantly greater than PFT of non-stone-bearing kidney (0.77 ± 0.60 cm vs. 0.67 ± 0.58 cm, p = .002) . During the follow-up periods (median 31 months), 21 (25.9%) patients experienced ipsilateral renal stone recurrence. In addition, Kaplan-Meier survival curves showed that patients with low PFT had a significant better RFS than those with high PFT (p = .012). In the univariable Cox analyses, male sex and high PFT were significantly associated with a poor RFS (p = .042 and .018, respectively). Moreover, both male sex and high PFT retained significance in the multivariable analyses (p = .045 and .020, respectively).

CONCLUSIONS

Our findings suggested that PFT is a noninvasive and feasible parameter, which may help in the risk stratification of renal stone recurrence in the follow-up periods.

The evolving view of thermogenic fat and its implications in cancer and metabolic diseases

The incidence of metabolism-related diseases like obesity and type 2 diabetes mellitus has reached pandemic levels worldwide and increased gradually. Most of them are listed on the table of high-risk factors for malignancy, and metabolic disorders systematically or locally contribute to cancer progression and poor prognosis of patients. Importantly, adipose tissue is fundamental to the occurrence and development of these metabolic disorders. White adipose tissue stores excessive energy, while thermogenic fat including brown and beige adipose tissue dissipates energy to generate heat. In addition to thermogenesis, beige and brown adipocytes also function as dynamic secretory cells and a metabolic sink of nutrients, like glucose, fatty acids, and amino acids. Accordingly, strategies that activate and expand thermogenic adipose tissue offer therapeutic promise to combat overweight, diabetes, and other metabolic disorders through increasing energy expenditure and enhancing glucose tolerance. With a better understanding of its origins and biological functions and the advances in imaging techniques detecting thermogenesis, the roles of thermogenic adipose tissue in tumors have been revealed gradually. On the one hand, enhanced browning of subcutaneous fatty tissue results in weight loss and cancer-associated cachexia. On the other hand, locally activated thermogenic adipocytes in the tumor microenvironment accelerate cancer progression by offering fuel sources and is likely to develop resistance to chemotherapy. Here, we enumerate current knowledge about the significant advances made in the origin and physiological functions of thermogenic fat. In addition, we discuss the multiple roles of thermogenic adipocytes in different tumors. Ultimately, we summarize imaging technologies for identifying thermogenic adipose tissue and pharmacologic agents via modulating thermogenesis in preclinical experiments and clinical trials.

Comparison of perinephric fat measurements between malignant and benign renal tumours

Objective

To investigate different parameters derived from the quantity and quality of perinephric fat, and to compare their effectiveness in predicting the malignant pathology of renal tumours.

Methods

Data from patients diagnosed with renal tumour between April 2014 and December 2020 were retrospectively reviewed, and patients were categorized into malignant or benign tumour groups. Fat parameters, including perinephric fat volume (PFV), perinephric fat area (PFA), perinephric fat thickness (PFT), and Mayo adhesive probability (MAP) score were measured using abdominal computed tomography scans. Between-group differences were assessed by analysis of variance and χ²-test. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the performance of perinephric fat parameters in diagnosing malignancy.

Results

A total of 109 patients were included. MAP score, PFV, PFA, and PFT were significantly increased in the malignant versus benign tumour group, and after correction for body mass index (BMI), the indexed PFV/BMI, PFA/BMI, and PFT/BMI values remained significantly higher in the malignant tumour group. All parameters showed fair predictivity of malignancy, with comparable area under the curve values in the ROC curve.

Conclusion

An increased amount of perinephric fat is predictive of malignant pathology for renal tumours. The predictive accuracy for each perinephric fat parameter remained fair after correcting for BMI.

Obesity, Weight Loss, Lifestyle Interventions, and Autosomal Dominant Polycystic Kidney Disease

Obesity remains a growing public health concern in industrialized countries around the world. The prevalence of obesity has also continued to rise in those with chronic kidney disease. Epidemiological data suggests those with overweight and obesity, measured by body mass index, have an increased risk for rapid kidney disease progression. Autosomal dominant polycystic kidney disease causes growth and proliferation of kidney cysts resulting in a reduction in kidney function in the majority of adults. An accumulation of adipose tissue may further exacerbate the metabolic defects that have been associated with ADPKD by affecting various cell signaling pathways. Lifestyle interventions inducing weight loss might help delay disease progression by reducing adipose tissue and systematic inflammation. Further research is needed to determine the mechanistic influence of adipose tissue on disease progression.

The thermogenic activity of adjacent adipocytes fuels the progression of ccRCC and compromises anti-tumor therapeutic efficacy

Clear cell renal cell carcinoma (ccRCC) preferentially invades into perinephric adipose tissue (PAT), a process associated with poor prognosis. However, the detailed mechanisms underlying this interaction remain elusive. Here, we describe a bi-directional communication between ccRCC cells and the PAT. We found that ccRCC cells secrete parathyroid-hormone-related protein (PTHrP) to promote the browning of PAT by PKA activation, while PAT-mediated thermogenesis results in the release of excess lactate to enhance ccRCC growth, invasion, and metastasis. Further, tyrosine kinase inhibitors (TKIs) extensively used in the treatment of ccRCC enhanced this vicious cycle of ccRCC-PAT communication by promoting the browning of PAT. However, if this cross-communication was short circuited by the pharmacological suppression of adipocyte browning via H89 or KT5720, the anti-tumor efficacy of the TKI, sunitinib, was enhanced. These results suggest that ccRCC-PAT cross-communication has important clinical relevance, and use of combined therapy holds great promise in enhancing the efficacy of TKIs.

Mayo Adhesive Probability (MAP) score of non-donated kidney aids in predicting post-operative renal function following donor nephrectomy

Background

To examine the association of preoperative Mayo Adhesive Probability (MAP) scores in the donor (MAP_d) and non-donor kidneys (MAP_nd) with post-donation renal function.

Methods

Three hundred thirty-one patients undergoing hand assisted laparoscopic donor nephrectomy (HALDN) were reviewed. MAP_d and MAP_nd were obtained. Estimated glomerular filtration rate (eGFR) was recorded preoperatively and at 1 day, 1 month, and 6 months postoperatively.

Results

Two hundred females and 131 males were evaluated with median BMI 26.4 kg/m² (range 17.1–39.6) and median age 45 years (range 19–78). MAP_d score was 0 for 231 patients (69.8%) and > 0 for 100 patients (30.2%). MAP_nd score was 0 for 234 patients (70.7%) and > 0 for 97 patients (29.3%). The median preoperative eGFR was 86.6 ml/min/1.73m² (range 48.8–138.4). After adjusting for preoperative eGFR, BMI, ASA score, and kidney sidedness, postoperative eGFR was associated with MAP score in the non-donated kidney (p = 0.014) but not in the donated kidney (p = 0.24). Compared to donors with MAP_nd = 0, donors with a MAP_nd > 0, mean eGFR was − 2.33 ml/min/1.73m² lower at postoperative day 1 (95% CI − 4.24 to − 0.41, p = 0.018), − 3.02 ml/min/1.73m² lower at 1 month (95% CI − 5.11 to − 0.93, p = 0.005), and − 2.63 ml/min/1.73m² lower at 6 months postoperatively (95% CI − 5.01 to − 0.26, p = 0.030).

Conclusions

MAP score > 0 in the non-donated kidney is associated with worse renal function in the 6 months following HALDN.

Three-dimensional evaluation of perirenal fat volume in patients with nephrolithiasis

The concept of adipose tissue as an organ unto itself represents a new medical construct; already differences in the volume of perirenal fat around a tumor-bearing kidney have been described. We hypothesized that renal calculi may have similar impact on perirenal fat or alternatively abnormalities in urinary metabolites may be the result of perirenal fat affecting renal metabolism and subsequent stone formation. Accordingly, we conducted a study utilizing three-dimensional imaging software to evaluate perirenal fat volume (PFV) in patients with nephrolithiasis. Among 40 patients with a history of unilateral nephrolithiasis who underwent percutaneous nephrolithotomy between 2010 and 2016, the following data were acquired: body mass index, past medical history, stone characteristics and composition (i.e., calcium oxalate, calcium phosphate, uric acid, and struvite calculi). In addition, patients were stratified by dominant stone composition (≥ 50% fraction). Bilateral PFV measurements were obtained using the preoperative computed tomography scan and specialized three-dimensional imaging software. The PFV of stone-bearing kidneys was significantly greater than non-stone-bearing kidneys (397.3 and 323 cc, respectively; p = 0.004), with the PFV difference in patients with CO-dominant stone-bearing kidneys reaching statistical significance (p = 0.003). Subgroup analysis showed greater PFV surrounding the stone-bearing kidney irrespective of gender (p = 0.03), with male patients possessing significantly greater stone-bearing (p = 0.01) and bilateral PFV (p = 0.01) compared to females. No significant correlations were found between PFV and stone volume or stone density. The PFV of calcium oxalate stone-bearing kidneys is significantly greater than non-stone-bearing kidneys for both male and female patients with nephrolithiasis.

Effect of perineoplasm perinephric adipose tissues on migration of clear cell renal cell carcinoma cells: a potential role of WNT signaling

To investigate the cellular and molecular interactions between clear-cell renal cell carcinoma (ccRCC) and perinephric adipose tissue (PAT), perineoplasm PAT, PAT away from the neoplasm, renal sinus and subcutaneous adipose tissues were collected at the time of renal surgery for renal masses and conditioned medium (CM) was generated from 62 patients. Perineoplasm PAT CMs from 44 out of 62 (about 71%) of patients with ccRCC or benign renal diseases (e.g. oncocytomas, angiomyolipomas, multicystic kidney, interstitial fibrosis, etc.) enhanced the migration of CaKi-2 cells. Perineoplasm PAT CMs from ccRCC significantly increased migration of ACHN and CaKi-2 cells by ~8.2 and ~2.4 folds, respectively, relative to those from benign renal diseases, whereas there is no significant difference in migration between ccRCC and benign renal diseases in CMs collected from culturing PAT away from neoplasm, renal sinus and subcutaneous adipose tissues. High Fuhrman Grade was associated with increased migration of Caki-2 cells by perineoplasm PAT CMs. Perineoplasm PATs from pT3 RCCs overexpressed multiple WNTs and their CMs exhibited higher WNT/ß-catenin activity and increased the migration of Caki-2 cells compared to CMs from benign neoplasms. Addition of secreted WNT inhibitory factor-1 recombinant protein into perineoplasm PAT CMs completely blocked the cell migration. These results indicate that WNT related factors from perineoplasm PAT may promote progression of local ccRCC to locally advanced (pT3) disease by increasing ccRCC cell mobility.

High perirenal fat thickness predicts a poor progression-free survival in patients with localized clear cell renal cell carcinoma

OBJECTIVES

The aim of the study was to assess the association between the progression-free survival (PFS) and perirenal fat thickness (PFT) in a population of histopathologically confirmed, localized clear cell renal cell carcinoma (ccRCC) patients.

METHODS

We retrospectively enrolled 174 patients with localized ccRCC at our center between December 2009 and December 2015. The preoperative visceral fat area (VFA), PFT, and subcutaneous fat area (SFA) were evaluated. Kaplan-Meier curves were used to assess the differences in PFS between the high and the low PFT groups within sexes. Potential independent prognostic factors of PFS were identified by univariable and multivariable Cox analyses.

RESULTS

During the follow-up period (median, 38 months), 27 patients (21 with high PFT and 6 with low PFT) experienced tumor progression. Kaplan-Meier curves revealed that high PFT was associated with a worse PFS than low PFT (P = 0.005). In the univariable Cox analyses, high VFA, high PFT, T stage, and the presence of sarcomatoid differentiation were significantly associated with a poor PFS. Moreover, both high PFT and VFA retained significance in the multivariable analysis.

CONCLUSION

We first report the evidence that high PFT presents as an independent risk factor of tumor progression in localized ccRCC. We suggest that this noninvasive and readily available preoperative parameter may help in the risk stratification of ccRCC patients before surgery.

Association between visceral and subcutaneous adiposity and clinicopathological outcomes in non-metastatic clear cell renal cell carcinoma

INTRODUCTION

Visceral adiposity has been inconsistently associated with clinicopathologic features and outcomes of clear cell renal cell carcinoma (ccRCC); however, most studies were conducted in non-Western populations. We evaluated the associations between visceral and subcutaneous adiposity and clinicopathological characteristics of non-metastatic ccRCC patients in a Western population.

METHODS

The medical records of 220 surgically treated ccRCC patients with documented preoperative body mass index (BMI) and computed tomography (CT) scans were retrospectively reviewed. Nineteen patients with stage IV disease were excluded. Visceral (VFA) and subcutaneous fat area (SFA) were computed from pre-operative CT scans. Correlations between obesity measures were assessed with Pearson correlation. Associations between obesity measures and pathologic features were evaluated using logistic regression models adjusted for sex. Overall survival (OS) probabilities were estimated using Cox regression analysis. The log-rank test was used for group comparisons.

RESULTS

The study cohort comprised 150 men and 51 women. Women had higher SFA (p = 0.01) but lower VFA (p < 0.001) than men. BMI was highly correlated with SFA (r = 0.804) and moderately correlated with VFA (r = 0.542). SFA and VFA were weakly correlated (r = 0.367). An increased BMI was associated with a better OS (p = 0.028). When adjusting for sex, neither SFA nor VFA was significantly associated with tumour grade, stage, or OS.

CONCLUSIONS

Consistent with prior reports, our study suggests that increased BMI is associated with a better OS for patient with nonmetastatic ccRCC. Despite the high correlation between SFA and BMI, neither SFA nor VFA were significantly associated with tumour stage, grade, or OS in the current study; however, further studies in larger cohorts are required to validate this finding.

Can radiologists and urologists reliably determine renal mass histology using standard preoperative computed tomography imaging?

PURPOSE

To determine the extent to which radiologists and urologists can predict histology using multiphasic CT imaging.

METHODS

Patients with a preoperative multiphasic CT undergoing surgery for a renal mass were identified between 2003 and 2013. Tumors >10 cm, locally advanced or metastatic disease, and patients managed by reviewers were excluded. A survey and deidentified scans were provided to reviewers. Sensitivity and accuracy in predicting histology was calculated for each reviewer. Correlation was assessed by the Fleiss kappa coefficient. Multivariable logistic regression determined factors associated with predictive accuracy for final pathology.

RESULTS

There were 120 patients who met criteria. Mean tumor size was 3.3 cm; there were 102 (85%) that were malignant, and 73% of these were clear-cell renal-cell carcinoma (RCC). The most common benign histology was angiomyolipoma (n=10, 56%) followed by oncocytoma (n=5, 28%). Correlation among reviewers was statistically fair for predicting malignant (κ=0.25) and final pathology (κ=0.22). Sensitivity for predicting malignant masses was 90%. Reviewers accurately predicted malignant pathology in 82% of cases and predicted final pathology in 58% of cases. Adjusted for size, scan type, and reviewer, clear-cell RCC vs benign histology was associated with 21 times increased odds of accurate pathologic identification (P<0.001).

CONCLUSIONS

Urologists and radiologists were able to accurately identify malignant histology in 82% of cases, although sensitivity for malignant histology was 90%. Developing a preoperative nomogram for identification of clear-cell RCC may be feasible and should be further explored.