Citations

Abstract Obesity is a major risk factor for a number of chronic diseases, including diabetes, cardiovascular diseases, and cancer. Expansion of the adipose mass requires adipocyte precursor cells that originate from multipotent adipose-derived stromal cells (ASCs), which in turn also participate in repair activities. ASC function might decline in a disease milieu, but it remains unclear whether ASC function varies during the development of obesity. We tested the hypothesis that microenvironmental inflammatory changes during development of metabolic disorders in obesity affect ASC function. Domestic pigs were fed with an atherogenic (n = 7) or normal (n = 7) diet for 16 weeks. Abdominal adipose tissue biopsies were collected after 8, 12, and 16 weeks of diet for ASC isolation and immunohistochemistry of in situ ASCs and tumor necrosis factor-α (TNF-α). Longitudinal changes in proliferation, differentiation, and anti-inflammatory functions of ASCs were assessed. At 16 weeks, upregulated TNF-α expression in adipose tissue from obese pigs was accompanied by increased numbers of adipocyte progenitors (CD24+/CD34+) in adipose tissue and enlarged adipocyte size. In vitro, ASCs from obese pigs showed enhanced adipogenic and osteogenic propensity, which was abolished by anti-TNF-α treatment, whereas lean ASCs treated with TNF-α showed enhanced adipogenesis. Furthermore, obese ASCs showed increased senescence compared with lean ASCs, whereas their immunomodulatory capacity was preserved. Adipose tissue inflammation promotes an increase in resident adipocyte progenitors and upregulated TNF-α enhances ASC adipogenesis. Thus, adipose tissue anti-inflammatory strategies might be a novel target to attenuate obesity and its complications. Significance Adipose-derived stromal cell (ASC) function might decline in a disease milieu, but it remains unclear whether ASC function varies during the development of obesity. This study tested the hypothesis that microenvironmental inflammatory changes during development of metabolic disorders in obesity affect ASC function. It was found that ASCs show increased propensity for differentiation into adipocytes, which is partly mediated by upregulated tumor necrosis factor-α (TNF-α), likely in their adipose tissue microenvironment. Furthermore, TNF-α magnified obese ASC senescence, although it did not regulate their anti-inflammatory properties. Thus, adipose tissue inflammation might be a novel therapeutic target to avert ASC maldifferentiation and senescence.

Abstract BACKGROUND Revascularization of a stenotic renal artery improves kidney function only in select patients with renovascular hypertension (HT) secondary to atherosclerosis. However, the effects of reversal of renovascular HT (RRHT) on the nonstenotic kidney are unclear. We hypothesized that concurrent hypercholesterolemia (HC) attenuates nonstenotic kidney recovery. METHODS Female domestic pigs were randomized as Normal, renovascular HT, HT+RRHT, HTC (renovascular HT and HC), and HTC+RHT ( n = 7 each). RRHT or sham was performed after 6 weeks of HT. Nonstenotic renal blood flow, glomerular filtration rate, and injurious pathways were studied 4 weeks later. RESULTS Mean arterial pressure increased similarly in HT and HTC and decreased after RRHT. Oxidative stress increased in HT and HTC kidneys, and decreased in HT+RRHT, but remained elevated in HTC+RRHT. Renal interstitial fibrosis, glomerulosclerosis, and tubular injury were all attenuated in HT+RRHT, but not HTC+RRHT. Endothelin-1 signaling and PGF2α isoprostane levels were elevated in both HTC and HTC+RRHT pigs. CONCLUSIONS RRHT reverses nonstenotic kidney injury in experimental renovascular HT, but concurrent HC blunts regression of kidney injury, possibly due to predominant vasoconstrictors and oxidative stress. These findings reinforce the contribution of the nonstenotic kidney and of prevailing cardiovascular risk factors to irreversibility of kidney dysfunction after revascularization.

Renovascular hypertension (RVH) leads to left ventricular (LV) hypertrophy and diastolic dysfunction, associated with increased cardiovascular mortality. Intrarenal delivery of endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) improves kidney function in porcine RVH, and the potent anti-inflammatory properties of MSCs may serve to blunt inflammatory mediators in the cardiorenal axis. However, their relative efficacy in attenuating cardiac injury and dysfunction remains unknown. This study tested the hypothesis that the car-dioprotective effect of EPCs and MSCs delivered into the stenotic kidney in experimental RVH are comparable. Pigs ( n = 7 per group) were studied after 10 weeks of RVH or control untreated or treated with a single intrarenal infusion of autologous EPCs or MSCs 4 weeks earlier. Cardiac and renal function (fast CT) and stenotic kidney release of inflammatory mediators (ELISA) were assessed in vivo, and myocardial inflammation, remodeling, and fibrosis ex vivo. After 10 weeks of RVH, blood pressure was not altered in cell-treated groups, yet stenotic kidney glomerular filtration rate (GFR), blunted in RVH, improved in RVH + EPC, and normalized in RVH + MSCs. Stenotic kidney release of monocyte chemoattractant protein (MCP)-1 and its myocardial expression were elevated in RVH + EPC, but normalized only in RVH + MSC pigs. RVH-induced LV hypertrophy was normalized in both EPC- and MSC-treated pigs, while diastolic function (E/A ratio) was restored to normal levels exclusively in RVH + MSCs. RVH-induced myocardial fibrosis and collagen deposition decreased in RVH + EPCs but further decreased in RVH + MSC-treated pigs. Intrarenal delivery of EPCs or MSCs attenuates RVH-induced myocardial injury, yet MSCs restore diastolic function more effectively than EPCs, possibly by greater improvement in renal function or reduction of MCP-1 release from the stenotic kidney. These observations suggest a therapeutic potential for EPCs and MSCs in preserving the myocardium in chronic experimental RVH.

Obesity and hypertension are major risk factors for cardiovascular diseases, and their growing coexistence accounts for an increase in adverse cardiac events, but the mechanisms are yet to be determined. We hypothesized that obesity exacerbates mitochondrial dysregulation imposed by hypertension and augments left ventricular dysfunction. Obesity-prone Ossabaw pigs were randomized to lean (standard diet) and obese (high-fat diet), without (Lean-sham and Obese-sham) or with renovascular hypertension (Lean-hypertension and Obese-hypertension), induced after 12 weeks of diet (n=7 each). Cardiac function, myocardial perfusion and oxygenation, and microvascular remodeling were assessed 4 weeks later. Mitochondrial biogenesis signals and structural proteins, respiratory chain complex activities, and mitochondrial self-degradation were examined, as was fibrosis. Obesity alone exerted no apparent effect on mitochondrial dynamics, but aggravated in hypertensive hearts the reduction of mitochondrial proteins, deoxyribonucleic acid content, and respiratory chain complex IV subunits activity, and amplified mitochondrial self-degradation. Synergistic interaction of obesity with hypertension also exacerbated myocardial fibrosis and left ventricular diastolic dysfunction. Mitochondrial content, respiratory chain complex IV subunits activity, and mitophagy were correlated with myocardial fibrosis. These findings suggest that obesity aggravates in renovascular hypertension cardiac mitochondrial aberrations. Mitochondrial function may regulate the progression of cardiac injury and functional deterioration in hypertension concomitant with obesity.

Morbidity and mortality attributable to hypertension are higher in black essential hypertensive (EH) compared with white EH patients, possibly related to differential effects on vascular injury and repair. Although circulating endothelial progenitor cells (EPCs) preserve endothelial integrity, inflammatory endothelial cells (IECs) detach from sites of injury and represent markers of vascular damage. We hypothesized that blood levels of IECs and inflammatory markers would be higher in black EH compared with white EH patients. Inferior vena cava and renal vein levels of CD34+/KDR+ (EPC) and VAP-1+ (IEC) cells were measured by fluorescence-activated cell sorting in white EH and black EH patients under fixed sodium intake and blockade of the renin–angiotensin system, and compared with systemic levels in normotensive control subjects (n=19 each). Renal vein and inferior vena cava levels of inflammatory cytokines and EPC homing factors were measured by Luminex. Blood pressure, serum creatinine, lipids, and antihypertensive medications did not differ between white and black EH patients, and EPC levels were decreased in both. Circulating IEC levels were elevated in black EH patients, and inversely correlated with EPC levels ( R 2 =0.58; P =0.0001). Systemic levels of inflammatory cytokines and EPC homing factors were higher in black EH compared with white EH patients, and correlated directly with IECs. Renal vein inflammatory cytokines, EPCs, and IECs did not differ from their circulating levels. Most IECs expressed endothelial markers, fewer expressed progenitor cell markers, but none showed lymphocyte or phagocytic cell markers. Thus, increased release of cytokines and IECs in black EH patients may impair EPC reparative capacity and aggravate vascular damage, and accelerate hypertension-related complications.

Abstract Ischemic kidney diseases are common clinical entities that bear high mortality and morbidity and may lead to irreversible loss of kidney function. Their pathophysiology is multifaceted, involves complex hormonal-immunological-cellular interactions, and leads to damage in multiple cell types, which is often resistant to conventional therapy. Thus, novel strategies are needed to repair the renal parenchyma and preserve kidney function. Mesenchymal stem cells (MSC) confer renal protection through paracrine/endocrine effects and to some degree possibly by direct engraftment. Their anti-inflammatory and immune-modulatory properties target multiple cascades in the mechanisms of ischemic kidney disease. This review focuses on recent progress on the use of MSC to prevent kidney injury in ischemic kidney injury, with a focus on the chronic form.

Obesity-metabolic disorders (ObM) often accompany renal artery stenosis (RAS). We hypothesized that the coexistence of ObM and RAS magnifies inflammation and microvascular remodeling in the stenotic kidney (STK) and aggravates renal scarring. Twenty-eight obesity-prone Ossabaw pigs were studied after 16 wk of a high-fat/high-fructose diet or standard chow including ObM-sham, ObM-RAS, Lean-RAS, or Lean-sham (normal control) groups. Single-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were assessed by multidetector computed tomography (CT), renal oxygenation and tubular transport capability by blood-oxygen-level-dependent MRI, and microcirculation by micro-CT for vessel density, and Western blotting for protein expressions of angiogenic factors (VEGF/FLK-1). Renal vein and inferior vena cava levels of inflammatory cytokines were measured to evaluate systemic and kidney inflammation. Macrophage (MØ) infiltration and subpopulations, fat deposition in the kidney, and inflammation in perirenal and abdominal fat were also examined. GFR and RBF were decreased in Lean-STK but relatively preserved in ObM-STK. However, ObM-STK showed impaired tubular transport function, suppressed microcirculation, and stimulated glomerulosclerosis. ObM diet interacted with RAS to blunt angiogenesis in the STK, facilitated the release of inflammatory cytokines, and led to greater oxidative stress than Lean-STK. The ObM diet also induced fat deposition in the kidney and infiltration of proinflammatory M1-MØ, as also in perirenal and abdominal fat. Coexistence of ObM and RAS amplifies renal inflammation, aggravates microvascular remodeling, and accelerates glomerulosclerosis. Increased adiposity and MØ-accentuated inflammation induced by an ObM diet may contribute to structural injury in the post-STK kidney.

Objective— Endothelial outgrowth cells (EOC) decrease inflammation and improve endothelial repair. Inflammation aggravates kidney injury in renal artery stenosis (RAS), and may account for its persistence upon revascularization. We hypothesized that EOC would decrease inflammatory (M1) macrophages and improve renal recovery in RAS. Approach and Results— Pigs with 10 weeks of RAS were studied 4 weeks after percutaneous transluminal renal angioplasty (PTRA+stenting) or sham, with or without adjunct intrarenal delivery of autologous EOC (10×10 6 ), and compared with similarly treated normal controls (n=7 each). Single-kidney function, microvascular and tissue remodeling, inflammation, oxidative stress, and fibrosis were evaluated. Four weeks after PTRA, EOC were engrafted in injected RAS-kidneys. Stenotic-kidney glomerular filtration rate was restored in RAS+EOC, RAS+PTRA, and RAS+PTRA+EOC pigs, whereas stenotic-kidney blood flow and angiogenesis were improved and fibrosis attenuated only in EOC-treated pigs. Furthermore, EOC increased cell proliferation and decreased the ratio of M1 (inflammatory)/M2 (reparative) macrophages, as well as circulating levels and stenotic-kidney release of inflammatory cytokines. Cultured-EOC released microvesicles in vitro and induced phenotypic switch (M1-to-M2) in cultured monocytes, which was inhibited by vascular endothelial growth factor blockade. Finally, a single intrarenal injection of rh-vascular endothelial growth factor (0.05 μg/kg) in 7 additional RAS pigs also restored M1/M2 ratio 4 weeks later. Conclusions— Intrarenal infusion of EOC after PTRA induced a vascular endothelial growth factor–mediated attenuation in macrophages inflammatory phenotype, preserved microvascular architecture and function, and decreased inflammation and fibrosis in the stenotic kidney, suggesting a novel mechanism and therapeutic potential for adjunctive EOC delivery in experimental RAS to improve PTRA outcomes.