Dapagliflozin added to metformin reduces perirenal fat layer in type 2 diabetic patients with obesity

Sodium-glucose co-transporters type 2 inhibitors (SLGT2i) are highly effective in controlling type 2 diabetes, but reported beneficial cardiovascular effects suggest broader actions on insulin resistance. Weight loss may be initially explained by glycosuria-induced net caloric output and secondary volumetric reduction, but its maintenance could be due to loss of visceral fat mass. Structured ultrasound (US) imaging of abdominal adipose tissue ("eco-obesity") is a recently described methodology used to measure 5 consecutive layers of abdominal fat, not assessable by DEXA or CT scan: superficial subcutaneous (SS), deep subcutaneous (DS), preperitoneal (PP), omental (Om) and right perirenal (RK). PP, Om and RK are predictors of metabolic syndrome (MS) with defined cut-off points. To assess the effect of SLGT2i on every fat depot we enrolled 29 patients with type 2 Diabetes (HbA1c 6.5-9%) and Obesity (IMC > 30 kg/m2) in an open-label, randomized, phase IV trial (EudraCT: 2019-000979-16): the Omendapa trial. Diabetes was diagnosed < 12 months before randomization and all patients were treatment naïve. 14 patients were treated with metformin alone (cohort A) and 15 were treated with metformin + dapaglifozin (cohort B). Anthropometric measures and laboratory tests for glucose, lipid profile, insulin, HOMA, leptin, ultrasensitive-CRP and microalbuminuria (MAL) were done at baseline, 3rd and 6th months. At 6th month, weight loss was -5.5 ± 5.2 kg (5.7% from initial weight) in cohort A and -8.4 ± 4.4 kg (8.6%) in cohort B. Abdominal circumference showed a -2.7 ± 3.1 cm and -5.4 ± 2.5 cm reduction, respectively (p = 0.011). Both Metformin alone (-19.4 ± 20.1 mm; -21.7%) or combined with Dapaglifozin (-20.5 ± 19.4 mm; -21.8%) induced significant Om fat reduction. 13.3% of cohort A patients and 21.4% of cohort's B reached Om thickness below the cut-off for MS criteria. RK fat loss was significantly greater in cohort B group compared to cohort A, at both kidneys. Only in the Met + Dapa group, we observed correlations between Om fat with leptin/CRP/MAL and RK fat with HOMA-IR. US is a useful clinical tool to assess ectopic fat depots. Both Metformin and Dapaglifozin induce fat loss in layers involved with MS but combined treatment is particularly effective in perirenal fat layer reduction. Perirenal fat should be considered as a potential target for cardiovascular dapaglifozin beneficial effects.

Thickened Perirenal Fat Predicts Poor Renal Outcome in Patients with Immunoglobulin A Nephropathy: A Population-Based Retrospective Cohort Study

Introduction

Perirenal fat is a pad that fills the retroperitoneal space outside the kidney, which affects kidney function in various ways. However, the association between perirenal fat and IgA nephropathy (IgAN) has not yet been elucidated. This study aimed to investigate the role of perirenal fat in predicting IgAN progression.

Methods

A total of 473 patients with biopsy-proven IgAN and follow-up information were recruited, and perirenal fat thickness (PFT) was measured using color Doppler ultrasonography at renal biopsy. Patients were divided into two groups according to the median PFT: the low-PFT group (PFT ≤1.34 cm, n = 239) and the high PFT group (PFT >1.35 cm, n = 234). A total of 473 healthy participants were included in the control group. Basic clinical characteristics were assessed at the time of renal biopsy, and the relationship between PFT and combined endpoints was analyzed. The renal composite endpoints were defined as a two-fold increase in blood creatinine level, end-stage renal disease (dialysis over 3 months). Kaplan-Meier survival analysis was used to explore the role of PFT in the progression of IgAN. Three clinicopathological models of multivariate Cox regression analysis were established to evaluate the association between PFT and renal prognosis in patients with IgAN.

Results

Compared to healthy subjects, patients with IgAN showed significantly higher PFT. After a median follow-up of 50 months, 75 of 473 patients (15.9%) with IgAN reached renal composite endpoints. Among those, 13 of 239 patients (5.4%) were in the low PFT group, and 62 of 234 patients (26.5%) were in the high PFT group (p < 0.001). The results of three Cox regression models (including demographics, pathological and clinical indicators, and PFT) demonstrated that a higher PFT was significantly associated with a higher risk of reaching renal composite endpoints in patients with IgAN.

Conclusion

This study indicated a positive relationship between PFT at renal biopsy and renal progression in patients with IgAN, suggesting that perirenal fat might act as a marker of poor prognosis in patients with IgAN.

Usefulness of hand-assisted retroperitoneal laparoscopic radical nephrectomy for extreme obese patients -a case report

We report a case of retroperitoneal laparoscopic radical nephrectomy (LRN) in which the addition of a hand port was necessary and effective. A 52-year-old man with obesity (BMI 40.6 kg/m2) was diagnosed with a 52-mm left renal cell carcinoma (cT1bN0M0). To avoid thick subcutaneous and visceral fat in the abdomen, we selected LRN using a retroperitoneal approach with four ports in the kidney position. During surgery, a large amount of flank pad and perirenal fat prevented us from securing a sufficient surgical field through traction of the kidney with a retractor. A pure laparoscopic procedure was not feasible;therefore, we added a hand port. Subsequently, we removed the flank pad from the hand port and secured the surgical field by tracing the kidney manually. Finally, hand-assisted LRN was completed without an open conversion. In retroperitoneal LRN, we rarely encounter patients for whom a pure laparoscopic procedure is not feasible because of the large amount of flank pad or perirenal fat. It is important to preoperatively confirm not only the BMI but also the amount of flank pad and perirenal fat on imaging. Hand-assisted LRN via the retroperitoneal approach can be safely performed even in extremely obese patients. J. Med. Invest. 71 : 187-190, February, 2024.

Perirenal fat thickness and liver fat fraction are independent predictors of MetS in adults with overweight and obesity suspected with NAFLD: a retrospective study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has a multidirectional relationship with metabolic syndrome (MetS) and used to be considered a hepatic manifestation of MetS. Perirenal fat, as a part of visceral adipose tissue (VAT), was reported to be correlated with MetS components, but data for intraorgan fat are lacking. This study was undertaken to assess the value of peripheral and intraorgan fat to predict MetS in adults with overweight and obesity with suspected NAFLD.

METHODS

We studied 134 sequential adults (mean age, 31.5 years; 47% female) with overweight and obesity with suspected NAFLD. All participants underwent abdominal magnetic resonance imaging (MRI) examination. Anthropometric and metabolic parameters and perirenal fat thickness (PRFT), subcutaneous adipose tissue thickness (SATT), liver fat fraction (LFF), pancreas fat fraction (PFF), and lumbar spine fat fraction (LSFF) were collected. MetS was defined according to the International Diabetes Federation (IDF) criteria. Statistical analyses included basic statistics, linear correlation and logistic regression analysis.

RESULTS

A total of 63 adults with MetS and 71 adults with advanced liver steatosis (grades 2 and 3) were included in our study. Patients with MetS had greater PRFT (p = 0.026) and LFF (p < 0.001), as well as greater homeostasis model assessment of insulin resistance (HOMA-IR), alanine transaminase (ALT), aspartate transaminase (AST), and decreased SATT. MetS patients had a higher proportion of advanced steatosis than those without MetS (P < 0.001). The MetS score was associated with PRFT and LFF. Logistic regression analysis showed that the PRFT and LFF were independent predictors of MetS after adjusting for age and sex. A cutoff of 9.15 mm for PRFT and 14.68% for LFF could be predictive of MetS.

CONCLUSIONS

This study shows that the absolute cutoff level of 9.15 mm for PRFT and 14.68% for LFF may be clinically important markers for identifying patients who are at high risk of MetS among adults with overweight and obesity with suspected NAFLD, irrespective of sex and age. Moreover, ectopic fat levels in pancreas and lumbar spine are positively associated with PRFT.

TRIAL REGISTRATION

Not applicable.

Differences in histomorphology and expression of key lipid regulated genes of four adipose tissues from Tibetan pigs

Tibetan pigs, an indigenous pig breed in China, have high overall fat deposition and flavorful and tasty meat. They are thus good models for studying adipogenesis. Few studies have been conducted focusing on expression of lipid regulated genes in different adipose tissues of Tibetan pigs. Therefore, we compared the difference of histomorphology and expression level of lipid regulated genes through qPCR and western blot in subcutaneous fat, perirenal fat, omental adipose tissue, and inguinal fat of Tibetan pigs. Our results showed that the area of subcutaneous adipocytes in Tibetan pigs was smaller, while the other three adipose tissues (perirenal fat, greater omentum fat, inguinal fat) had cell areas of similar size. The gene expression of FABP4, FASN, FABP3, and ME1 in subcutaneous fat was significantly higher than that in perirenal fat. Furthermore, the protein expression of FABP4 was significantly lower in subcutaneous fat than in perirenal fat (p < 0.05), and the expression of FASN was higher in greater omentum fat than in subcutaneous fat (p = 0.084). The difference in adipocyte cell size and expression of lipid-regulated genes in adipose tissues from the various parts of the pig body is likely due to the different cellular lipid metabolic processes. Specially, FABP4 and FASN may be involved in the regulation of fat deposition in different adipose tissues of Tibetan pigs.

Immunoglobulin G4-related kidney disease involving the renal pelvis and perirenal fat: A case report

BACKGROUND

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is an autoimmune disease associated with chronic and progressive inflammation and fibrosis. It is difficult to differentiate IgG4-RD involving the kidney from infectious diseases and malignancy on imaging.

CASE SUMMARY

We report the case of a 51-year-old Chinese man whose abdominal computed tomography scan showed diffuse bilateral enlargement of the kidneys and perirenal fat, thickening of the renal pelvic walls, and hydronephrosis of the right kidney. Relevant laboratory test results showed a serum creatinine level of 464 μmol/L. The patient was diagnosed with acute renal failure and was started on intermittent hemodialysis. Further tests revealed high serum IgG4 levels (20.8 g/L) and an enlarged right submaxillary lymph node. Biopsy and histopathological examination of the enlarged node led to the diagnosis of IgG4-RD. After corticosteroid therapy, his serum creatinine level quickly decreased to near normal levels.

CONCLUSION

IgG4-RD affecting the renal pelvis or perirenal fat is rare, with atypical imaging features. Multidisciplinary consultation is critical for accurate diagnosis and treatment of this disease. Suspected cases should undergo biopsy to avoid misdiagnosis.

Perirenal fat metastasis of prostate cancer

A 72-year-old male underwent an abdominal CT scan, which revealed a 17-mm nodular incidentaloma in fat tissue in the left perirenal space. Retroperitoneoscopic surgery was performed to remove the tumor and histopathological results revealed a PSA-positive adenocarcinoma, which was diagnosed as a metastatic lesion associated with prostate cancer. PSA was high at 30.083 ng/ml and MRI findings showed extracapsular extension of prostate cancer in the left peripheral zone of the prostate gland. Biopsy results with a Gleason score of 4 + 4 confirmed the diagnosis of prostate cancer. The case was diagnosed as prostate cancer metastasis in perirenal fat tissue.

Fatty Acids of Microbial Origin in the Perirenal Fat of Rats (Rattus norvegicus domestica) and Guinea Pigs (Cavia porcellus) Fed Various Diets

Guinea pigs are assumed to practice caecotrophy to a higher degree than rats. Studies from leporids suggest that through the practice of caecotrophy, hindgut fermenting species could build up microbial fatty acids (FA) in body tissues. We hypothesized that microbial FA would be detectable in the body tissue of guinea pigs and rats, and this to a higher degree in guinea pigs. Twenty-four rats and guinea pigs were fed with four different pelleted diets (lucerne-, meat-, meat-bone-, insect-based) in groups of six animals for 8 weeks. Perirenal adipose tissue differed in FA composition between the species in spite of the common diets. FA typically associated with microbial activity (saturated FA (SFA; typically 18:0), monounsaturated FA (MUFA; typically trans-fatty acids TFA), and odd- and branched-chain FA (Iso-FA)), were all detected. Guinea pigs had higher SFA levels than rats except on the lucerne diet. Concentrations of 18:0 were higher for guinea pigs on the meat and bone diet. Iso-FA concentrations in guinea pigs exceeded those of rats on all diets. FA profiles with a microbial fingerprint appear-although in low proportions-in the body tissue of both species, and this seemingly to a higher extent in guinea pigs. With respect to whether consumption of rodent meat rich in microbial FA has particular effects on human health as shown for ruminant products, microbial FA concentrations are probably too low to cause any distinct effects.

Perirenal fat thickness is associated with metabolic risk factors in patients with chronic kidney disease

Background

Adipose tissue accumulation in specific body compartments has been associated with diabetes, hypertension and dyslipidemia. Perirenal fat (PRF) may lead to have direct lipotoxic effects on renal function and intrarenal hydrostatic pressure. This study was undertaken to explore the association of PRF with cardiovascular risk factors and different stages of chronic kidney disease (CKD).

Methods

We studied 103 patients with CKD of different stages (1 to 5). PRF was measured by B-mode renal ultrasonography in the distal third between the cortex and the hepatic border and/or spleen.

Results

The PRF thickness was greater in CKD patients with impaired fasting glucose than in those with normal glucose levels (1.10 ± 0.40 cm vs. 0.85 ± 0.39 cm, P < 0.01). Patients in CKD stages 4 and 5 (glomerular filtration rate [GFR] < 30 mL/min/1.73 m²) had the highest PRF thickness. Serum triglyceride levels correlated positively with the PRF thickness; the PRF thickness was greater in patients with triglyceride levels ≥ 150 mg/dL (1.09 ± 0.40 cm vs. 0.86 ± 0.36 cm, P < 0.01). In patients with a GFR < 60 mL/min/1.73 m², uric acid levels correlated positively with the PRF thickness (P < 0.05).

Conclusion

In CKD patients, the PRF thickness correlated significantly with metabolic risk factors that could affect kidney function.

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.

Prospective assessment and histological analysis of adherent perinephric fat in partial nephrectomies

OBJECTIVES

The complexity of partial nephrectomy (PN) is partly anticipated by morphometric tumor-based scores that do not consider patient-related issues such as adherent perinephric fat (APF). Also, the objective is to prospectively assess the predictive factors of APF during PN, its effect on complications, and to correlate it to the histological reality.

METHODS

A total of 125 consecutive patients undergoing robotic or open PN were prospectively included. The Mayo adhesive probability score (MAP score) was compared to the peroperative presence of APF defined by a score≥2. Adipose tissue was analyzed histologically for fibrosis and inflammatory infiltrate of CD68+macrophages. Univariate and multivariate logistic regression analyses were performed to evaluate predictive factors of APF, and outcomes were compared using chi-square and Kruskal-Wallis tests.

RESULTS

APF was present in 51 patients (40.8%) and associated with slight longer operating time and increased blood loss. Warm ischemia time, margins, transfusion, and the Clavien-Dindo score were not different. In multivariate analysis, only male sex, age, waist circumference, fat density on computed tomography, and MAP score were significant predictors of APF. A radioclinical score was more predictive of APF than MAP score alone. Histologically, there was no macrophage infiltration but larger adipocytes in APF without significant differences in fibrosis.

CONCLUSIONS

APF can be accurately predicted using radioclinical data as the MAP score, combined with sex, age, and waist circumference. APF is associated with increased operative time and blood loss without postoperative complications. Histological analysis finds larger adipocytes in APF without inflammatory infiltrate, and no difference in fibrosis.