Expansive Vascular Remodeling and Increased Vascular Calcification Response to Cholecalciferol in a Murine Model of Obesity and Insulin Resistance

Objective- We hypothesized that ob/ob mice develop expansive vascular remodeling associated with calcification. Approach and Results- We quantified and investigated mechanisms of vascular remodeling and vascular calcification in ob/ob mice after vitamin D₃(VD) stimulation or PBS (control), compared with C57BL/6 mice. Both ob/ob (OBVD [VD-treated ob/ob mice]) and C57BL/6 (C57VD [VD-treated C57BL/6 mice]) received 8×10³ IU/day of intraperitoneal VD for 14 days. Control ob/ob (OBCT [PBS-treated ob/ob mice]) and C57BL/6 (C57CT [PBS-treated C57BL/6 mice]) received intraperitoneal PBS for 14 days. Hypervitaminosis D increased the external and internal elastic length in aortae from OBVD, resulting in increased total vascular area and lumen vascular area, respectively, which characterizes expansive vascular remodeling. OBVD decreased the aortic wall thickness, resulting in hypotrophic vascular remodeling. We demonstrated increased collagen deposition, elastolysis, and calcification in aortae from OBVD. Our results showed a positive correlation between expansive vascular remodeling and vascular calcification in OBVD. We demonstrated increased serum calcium levels, augmented Bmp (bone morphogenetic protein)-2 and osteochondrogenic proteins expression in OBVD aortae. Furthermore, aortae from OBVD increased oxidative stress, coincidently with augmented in situ MMP (matrix metalloproteinase) activity and exhibited no VDR (VD receptor) inhibition after VD. Conclusions- Our data provide evidence that obese and insulin-resistant mice (ob/ob) developed expansive hypotrophic vascular remodeling correlated directly with increased vascular calcification after chronic VD stimulation. Positive hypotrophic vascular remodeling and vascular calcification in this mouse model is possibly mediated by the convergence of absence VDR downregulation after VD stimulation, increased reactive oxygen species generation, and MMP activation.

Abstract 607: Increased Vitamin D 3- induced Kidney Dysfunction Associates With Intrarenal VascularCalcification in Type 2 Diabetes Mellitus Murine Model

Vascular calcification associates with increased cardiovascular morbidity and mortality in patients with diabetes mellitus and end-stage renal disease. We evaluated intrarenal vascular calcification and renal dysfunction after either vitamin D 3 (VitD 3 4.4-6.4x104 IU/day i.p. for 21 days) or saline in ob/ob mice (n=12), a murine model of type 2 diabetes mellitus (T2DM), in comparison to paired C57BL/6 mice (n=12). The animal protocol #2242-14 was approved by Institutional ethics committee. VitD3 increased serum calcium levels in both animal strains. Serum creatinine increased in VitD3-treated mice (92% and 43% in ob/ob and C57BL/6 respectively), while serum urea levels decreased in ob/ob and increased in C57BL/6 after calcifying protocol. Both VitD 3 -treated ob/ob and C57BL/6 decreased 24-hour urine volume, which was more pronounced in diabetic animals (~5 times and ~1.5 reduction in ob/ob and in C57BL/6 respectively). Moreover, creatinine clearance decreased in VitD 3 -treated mice, especially in ob/ob animals (~7 and ~3 fold reduction in ob/ob and C57BL/6, respectively). Additionally, urinary albumin/creatinine ratio increased after VitD 3 administration in ob/ob mice only (~13 times in comparison to control ob/ob). Alizarin Red S, Von Kossa and Osteosense TM revealed that only ob/ob mice developed extensive intrarenal vascular calcification after VitD 3 . Interestingly, histomorphometric analysis of the femur showed that VitD 3 induced similar osteomalacia in both ob/ob and C57BL/6 mice. Coincidently with increased intrarenal vascular mineralization in ob/ob, confocal immunofluorescence analysis demonstrated that Bone Morphogenetic Protein-2 (BMP-2) was highly expressed in these arteries exclusively in ob/ob. These data suggest a greater susceptibility of T2DM murine model to VitD 3 , in comparison to paired C57BL/6 littermates to induce kidney dysfunction associated with increased intrarenal vascular calcification, together with BMP-2 signaling pathway activation. These findings were independent of bone remodeling and serum calcium levels. In conclusion, this study unfolded novel mechanisms of progressive renal dysfunction in T2DM after VitD 3 in vivo associated with increased intrarenal vascular calcification.

Abstract 544: Diabetes Mellitus Impacts on Vascular Calcification in Peripheral Arterial Disease Patients but Does Not Further Activates Osteogenic Markers in Beta-Glycerophosphate Stimulated Vascular Smooth Muscle Cells

Introduction: Diabetes mellitus (DM) accelerates vascular calcification (VC) in peripheral arterial disease (PAD), increasing limb ischemia and amputation risk. Although DM and VC implicates in PAD, the mechanisms underlying vascular smooth muscle cells (SMC) osteochondrogenic differentiation in this setting are scarce.

Objectives: To assess VC and osteogenic mRNA/protein expression (Msx2, Runx2 and ALPL) in arteries and in primary SMC isolated from PAD patients with DM (n=3), without DM (n=2) and individuals without PAD (control [CTL], n=2) that underwent amputation.

Methods: Ethical committee approved study and patients signed informed consent. 5-7 th passages SMC were incubated without (untreated) or with β-glycerophosphate 10mM (β-GP) for 48h (mRNA expression), 72h (protein expression) and 14 days (calcification). In addition, we performed tissue immunofluorescence and Alizarin Red S.

Results: Untreated PAD+DM SMC increased calcification (4.6±1.2) in comparison to PAD without DM patients (2.5±0.2) and CTL individuals (1.0±0.07). β-GP further increased calcification in respective groups (51.3±4.7; 13.5±1.1 and 9.8±1.2). Msx2 mRNA expression decreased in CTL SMC after β-GP (48h) and did not change in PAD without DM and in PAD+DM SMC. Msx2 protein expression decreased in all groups after calcifying medium (72h). Moreover, Runx2 mRNA expression increased in β-GP-treated PAD+DM SMC and ALPL mRNA expression augmented in β-GP-treated SMC from PAD without DM patients. However, Runx2 and ALPL protein expression was not modulated by calcifying medium (72h) in all groups. Interestingly, immunofluorescence of arterial samples demonstrated increased osteochondrogenic protein expression (Msx2, Runx2 and ALPL) around calcifying foci in PAD+DM group (+++) versus PAD without DM (++) and versus CTL (+) patients. Coincidently, PAD+DM group showed augmented vascular calcification (19x10 4 ±10x10 4 ; 7x10 4 ±2x10 4 ; 3x10 3 ±10 -2 μm 2 ).

Conclusion: We demonstrated increased calcification in arteries from amputated PAD+DM patients and in respective SMC without and with calcifying medium. Although we found augmented osteochondrogenic protein expression in the vessel wall from PAD+DM individuals this was not robustly shown in isolated SMC in vitro .

Abstract 709: Aging Determines Different Osteochondrogenic Protein Expression Profile Associated With Increased Calcification and Elastocalcinosis in Diabetic Patients Submitted to Amputation

Peripheral artery disease (PAD) frequently occurs in diabetes mellitus (DM) and associates with limb ischemia and amputation. Vascular calcification, which is very prevalent both in DM and in the elderly, contributes to PAD pathophysiology and further increases amputation risk. Our objectives were to quantify vascular calcification, elastic and collagen fiber content, besides osteochondrogenic protein expression in arteries from 2 diabetic patients at the extremes of age. Femoral and dorsalis pedis artery from a 92-year-old male (O) and a 40-year-old male (Y), both with DM, were harvested at the time of amputation caused by limb ischemia. Other cardiovascular risk factors were similar among patients. Specimens were fixed in buffered formaldehyde, processed and stained for hematoxylin-eosin, Verhoeff-van-Gieson and Masson’s trichrome. Immunohistochemical analysis was performed to assess osteogenic protein expression such as RUNX2, alkaline phosphatase (ALP) and Osterix (OSX), which are upregulated during vascular smooth muscle cell reprogramming to an osteogenic phenotype, responsible for hydroxyapatite deposition. Arteries from 92-year-old patient showed markedly architectural changes of the vascular wall in comparison with the younger patient sample, such as decreased collagen (O=0.8±0.2% versus Y=33.5±5.2% area/field, p<.05) and elastic fibers (O=1.6±0.4% vs. Y=7.8±1.5% area/field, p<.05) content. Coincidently, we demonstrated increased vascular calcification (O=209.7±27.5mm 2 /field vs. Y=30.6±6.3 mm 2 /field). Osteochondrogenic protein expression also showed opposing results: OSX stained around large calcification nuclei, mostly in the older, but not in the younger patient samples. Furthermore, RUNX2 and ALP expression, which determines early osteoblastic cell differentiation, occurred around small calcium deposits, mainly in the 40-year-old patient. We demonstrated that age and time-length exposure to diabetes are predictive of collagen and elastic fibers content associated with increased calcification area. Moreover, osteochondrogenic protein expression profile favors RUNX2 and ALP in the younger vs OSX in the older patient respectively, implying different stages of the disease.

Indigofera suffruticosa Mill as new source of healing agent: involvement of prostaglandin and mucus and heat shock proteins

ETHNOPHARMACOLOGICAL RELEVANCE

Indigofera suffruticosa is specie typical of the "Cerrado" or Brazilian savannah; it is a member of the Fabaceae family - in folkmedicine is used for gastric disorders, infection and inflammation.

AIM OF THE STUDY

Ethyl acetate fraction (AcF) and aqueous fraction (AqF) of the methanolic extract of I. suffruticosa leaves were evaluated against acute gastric ulcer. The AcF fraction was selected to assess its activity in ulcer healing and its gastroprotective effects via mucus and gastric secretion.

MATERIALS AND METHODS

The gastroprotective action of AcF and AqF fractions were evaluated in a rodent experimental model. The action mechanisms, involvements of the antisecretory action, mucus and prostaglandin production, toxicological and healing activity of the AcF (100mg/kg, p.o.) were evaluated. We also used histological analysis (HE and PAS) and immunohistochemical (PCNA and HSP-70) assays to evaluate the effects of I. suffruticosa.

RESULTS

AcF significantly inhibited the gastric mucosal damage caused by ethanol. This effect was statistically significant in 100mg/kg group compared vehicle. AcF did not interfered with gastric secretion, significantly increased the PGE(2) and mucus production (validated in PAS technique). The gastroprotection was attenuated by pretreatment with N-ethylmaleimide, but not L-NAME. In acid-acetic-induced ulcer model AcF accelerated ulcer healing. Immunohistochemistry analysis showed induction of proliferating cell (PCNA) and heat shock protein (HSP 70).

CONCLUSIONS

These results showed that AcF acted as gastroprotective agent stimulating prostaglandin, mucus and HSP70.

Antioxidant activity of indigo and its preventive effect against ethanol-induced DNA damage in rat gastric mucosa

Ethanol-induced oxidative damage is commonly associated with the generation of reactive oxygen molecules, leading to oxidative stress. Considering that antioxidant activity is an important mechanism of action involved in cytoprotection, the aim of this work was to evaluate the antioxidant properties of the alkaloid indigo (1) (2 mg/kg, P. O.), obtained from the leaves of Indigofera truxillensis Kunth (Fabaceae), on rat gastric mucosa submitted to ethanol-induced (100%, 1 mL, P. O.) gastric ulcer. Enzymatic assays and DNA fragmentation analysis were performed. When ethanol was administered to the control group, the sulfhydryl content (SH) and the glutathione peroxidase (GPx) activity decreased by 41% and 50%, respectively; in contrast, superoxide dismutase (SOD) and glutathione reductase (GR) activities increased by 56% and 67%, respectively. Additionally, myeloperoxidase (MPO) activity, a marker for free radical generation caused by polymorphonuclear neutrophil (PMN) tissue infiltration, also increased 4.5-fold after ethanol treatment. Rat gastric mucosa exposed to ethanol showed DNA fragmentation. Indigo alkaloid pretreatment protected rats from ethanol-induced gastric lesions. This effect was determined by the ulcerative lesion area (ULA), indicating an inhibition of around 80% at 2 mg/kg. This alkaloid also diminished GPx activity, which was higher than that observed with ethanol alone. However, this effect was counterbalanced by increased GR activity. Indigo was unable to restore alterations in SOD activity promoted by ethanol. After indigo pretreatment, SH levels and MPO activity remained normal and gastric mucosa DNA damage caused by ethanol was also partially prevented by indigo. These results suggest that the gastroprotective mechanisms of indigo include non-enzymatic antioxidant effects and the inhibition of PMN infiltration which, in combination, partially protect the gastric mucosa against ethanol-induced DNA damage.

Glucocorticoid receptor and Beta-adrenoceptor expression in epididymal adipose tissue from stressed rats

Adipocytes isolated from epididymal adipose tissue of foot-shock stressed rats are supersensitive to isoprenaline and subsensitive to norepinephrine. These alterations are probably mediated by a stress-induced increase in plasma corticosterone levels. We investigated whether foot-shock stress modifies the expression of glucocorticoid receptors (GRs) and beta-adrenergic protein receptors (beta-ARs) in epididymal adipose tissue from rats submitted to one daily foot-shock session on three consecutive days. This stress protocol caused decreases in GR, beta(1)-AR, and beta(3)-AR protein levels, but caused an increase in beta(2)-AR. These results confirm and support previous functional studies. The alterations in protein expression may be modulated by the high corticosterone levels that downregulate the glucocorticoid receptor.

Effect of swimming session duration and repetition on metabolic markers in rats

The aim of this study was to investigate the profile of metabolites in male rats subjected to 50-60 min of swimming on three protocols: group A, a single 50 min swimming session; group B, one session a day for three days (5 min on day 1, 15 min on day 2 and 30 min on day 3); and group C, one session a day for 5 days, with increasing duration from 5 min on day 1, 15, 30, 45 and 60 min on consecutive days. The interval between sessions was 24 h. Measurements were made after the last swimming session. Controls did not swim. The glycogen content of liver and gastrocnemius and soleus muscle was depleted in the three groups that swam, but blood glucose concentration was significantly increased only in group B. Serum lactate concentrations were greater than the controls in groups A and B. There were significant increases in serum free fatty acid concentrations in all groups that swam. The increases in plasma free fatty acids may have resulted from lipolysis stimulated by endogenous catecholamines in groups A and C, since basal lipolysis measured in vitro was unchanged by swimming. The large increase in basal lipolysis in group B may have contributed to the rise in plasma free fatty acids. Adipocytes from rats in groups A and B were supersensitive to epinephrine, whereas those from group C were not. We conclude that the metabolic alterations were less pronounced after the last of five swimming sessions over 5 days than after a single session, even though session duration and the contribution of the physical component were similar. Glucose mobilization, but probably not utilization, was similar in the three groups that swam. The mechanisms of lipid mobilization from adipose tissue differed, depending on the stress paradigm. The metabolic changes in groups A and B indicated that three daily swimming sessions were insufficient to cause adaptation. The results contrast with previous findings for foot-shock stress, which leads to sensitization rather than adaptation in response to repeated stimuli.

Stress-induced alteration in the lipolytic response to beta-adrenoceptor agonists in rat white adipocytes

We analysed the sensitivity to beta-adrenoceptor agonists in epididymal adipose cells from rats submitted to a stress protocol previously reported to induce alterations in sensitivity to catecholamines in cardiac tissue from rats. Food intake and body weight were lower, whereas adipocytes basal lipolysis was higher (control: 0.59 +/- 0.04; stress: 1.00 +/- 0.11, micromol glycerol/100 mg total lipids/100 min) in stressed compared to control rats. The responses to isoprenaline (pD(2) control: 7.46 +/- 0.11; stress: 8.11 +/- 0.17), adrenaline (pD(2) control: 5.78 +/- 0. 20; stress: 6.13 +/- 0.18), and salbutamol (pD(2) control: 5.64 +/- 0.28; stress: 5.92 +/- 0.34) were sensitized, and the lipolytic responses to norepinephrine (pD(2) control: 6.98 +/- 0.13; stress: 6. 41 +/- 0.12) and to BRL37344 (pD(2) control: 8.43 +/- 0.19; stress: 7.54 +/- 0.21) were desensitized. Responses to the higher concentration (100 microm) of isoprenaline (control: 1.80 +/- 0.18; stress: 2.24 +/- 0.10 micromol glycerol/100 mg total lipids/100 min), epinephrine (control: 1.64 +/- 0.17; stress: 2.24 +/- 0.14 micromol glycerol/100 mg total lipids/100 min), salbutamol (control: 0.65 +/- 0.11; stress: 1.21 +/- 0.41 micromol glycerol/100 mg total lipids/100 min), and d-butyryl-cAMP (control: 1.59 +/- 0.17; stress: 2.72 +/- 0.25) were significantly enhanced in adipocytes from stressed rats. pD(2) or maximum response to CGP12177 were not altered. Supersensitivity to isoprenaline was abolished by 50 nm ICI118,551 but was not modified by 100 nm metoprolol. However, subsensitivity to norepinephrine and to BRL37344 was abolished by 100 nM metoprolol. Our results suggest that in epididymal adipocytes from stressed rats there is a desensitization of the response to adrenoceptor agonists mediated by beta(1)-adrenoceptors together with a sensitization of the response mediated by beta(2)-adrenoceptors. beta(3)-adrenoceptors seem to be resistant to the stress effect.