Obesity-Related Chronic Kidney Disease-The Role of Lipid Metabolism

Efficacy of Kaempferia parviflora in a mouse model of obesity-induced dermatopathy

Obesity results from excessive energy intake and physical inactivity, and predisposes one to various diseases. One of these reasons is that enlargement of adipocytes raises the lipid metabolic abnormalities that affect various organs. The skin is one such organ, and it has been reported that subcutaneous adipocyte cells secrete various factors and these factors are involved in reduction of dermal collagen fibers and fragility of the skin in obesity. The present study explored the efficacy of Kaempferia parviflora (KP) in preventing obesity-induced dermatopathy. We used Tsumura Suzuki obese diabetes (TSOD) mice as an obesity model. TSOD mice were fed a standard diet (MF) mixed with either an ethanol extract from KP (KPE), polymethoxyflavonoid-rich extract from KP (PMF), or polymethoxyflavonoid-poor extract from KP (X). We then evaluated the effect of these three KP fractions on aging-like skin damage induced by UVB irradiation. KPE and PMF caused a significant decrease of mouse body weight, and suppressed the increase in the thickness of the subcutaneous fat layer. In addition, KPE shifted the frequency of subcutaneous adipocyte sizes towards smaller cells possibly via its polypharmacological actions. Scanning electron microscopy revealed that the stereostructure of the collagenous fibers in the dermis was better retained in the KPE and PMF groups, in that order. These results offer the first evidence that KPE can attenuate obesity-induced dermatopathy more effectively than PMF, suggesting that KPE (or KP) might be a candidate supplement for preventing obesity-related skin disorders.

Mouse Models of Diabetes, Obesity and Related Kidney Disease

Multiple rodent models have been used to study diabetic kidney disease (DKD). The purpose of the present study was to compare models of diabetes and obesity-induced metabolic syndrome and determine differences in renal outcomes. C57BL/6 male mice were fed either normal chow or high fat diet (HFD). At postnatal week 8, chow-fed mice were randomly assigned to low-dose streptozotocin (STZ, 55 mg/kg/day, five consecutive days) or vehicle control, whereas HFD-fed mice were given either one high-dose of STZ (100 mg/kg) or vehicle control. Intraperitoneal glucose tolerance tests were performed at Week 14, 20 and 30. Urinary albumin to creatinine ratio (ACR) and serum creatinine were measured, and renal structure was assessed using Periodic Acid Schiff (PAS) staining at Week 32. Results showed that chow-fed mice exposed to five doses of STZ resembled type 1 diabetes mellitus with a lean phenotype, hyperglycaemia, microalbuminuria and increased serum creatinine levels. Their kidneys demonstrated moderate tubular injury with evidence of tubular dilatation and glycogenated nuclear inclusion bodies. HFD-fed mice resembled metabolic syndrome as they were obese with dyslipidaemia, insulin resistance, and significantly impaired glucose tolerance. One dose STZ, in addition to HFD, did not worsen metabolic features (including fasting glucose, non esterified fatty acid, and triglyceride levels). There were significant increases in urinary ACR and serum creatinine levels, and renal structural changes were predominantly related to interstitial vacuolation and tubular dilatation in HFD-fed mice.

Paternal High Fat Diet in Rats Leads to Renal Accumulation of Lipid and Tubular Changes in Adult Offspring

Along with diabetes and obesity, chronic kidney disease (CKD) is increasing across the globe. Although some data support an effect of maternal obesity on offspring kidney, the impact of paternal obesity is unknown; thus, we have studied the effect of paternal obesity prior to conception. Male Sprague Dawley rats were fed chow diet or high fat diet (HFD) for 13-14 weeks before mating with chow-fed females. Male offspring were weaned onto chow and killed at 27 weeks for renal gene expression and histology. Fathers on HFD were 30% heavier than Controls at mating. At 27 weeks of age offspring of obese fathers weighed 10% less; kidney triglyceride content was significantly increased (5.35 ± 0.84 vs. 2.99 ± 0.47 μg/mg, p < 0.05, n = 8 litters per group. Histological analysis of the kidney demonstrated signs of tubule damage, with significantly greater loss of brush border, and increased cell sloughing in offspring of obese compared to Control fathers. Acat1, involved in entry of fatty acid for beta-oxidation, was significantly upregulated, possibly to counteract increased triglyceride storage. However other genes involved in lipid metabolism, inflammation and kidney injury showed no changes. Paternal obesity was associated with renal triglyceride accumulation and histological changes in tubules, suggesting a mild renal insult in offspring, who may be at risk of developing CKD.