Preoperative dietary restriction reduces intimal hyperplasia and protects from ischemia-reperfusion injury

Abstract

Objective: Whereas chronic overnutrition is a risk factor for surgical complications, long-term dietary restriction (reduced food intake without malnutrition) protects in preclinical models of surgical stress. Building on the emerging concept that acute preoperative dietary perturbations can affect the body's response to surgical stress, we hypothesized that short-term high-fat diet (HFD) feeding before surgery is detrimental, whereas short-term nutrient/energy restriction before surgery can reverse negative outcomes. We tested this hypothesis in two distinct murine models of vascular surgical injury, ischemia-reperfusion (IR) and intimal hyperplasia (IH).

Methods: Short-term overnutrition was achieved by feeding mice a HFD consisting of 60% calories from fat for 2 weeks. Short-term dietary restriction consisted of either 1 week of restricted access to a protein-free diet (protein/energy restriction) or 3 days of water-only fasting immediately before surgery; after surgery, all mice were given ad libitum access to a complete diet. To assess the impact of preoperative nutrition on surgical outcome, mice were challenged in one of two fundamentally distinct surgical injury models: IR injury to either kidney or liver, or a carotid focal stenosis model of IH.

Results: Three days of fasting or 1 week of preoperative protein/energy restriction attenuated IH development measured 28 days after focal carotid stenosis. One week of preoperative protein/energy restriction also reduced plasma urea, creatinine, and damage to the corticomedullary junction after renal IR and decreased aspartate transaminase, alanine transaminase, and hemorrhagic necrosis after hepatic IR. However, exposure to a HFD for 2 weeks before surgery had no significant impact on kidney or hepatic function after IR or IH after focal carotid stenosis.

Conclusions: Short-term dietary restriction immediately before surgery significantly attenuated the vascular wall hyperplastic response and improved IR outcome. The findings suggest plasticity in the body's response to these vascular surgical injuries that can be manipulated by novel yet practical preoperative dietary interventions.

Conflict of interest statement

CONFLICTS OF INTEREST

JRM has consulted for L-Nutra, a company that develops medical food to fight diseases, including cancer. None of the other authors declares any conflict of interest.

Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Influence of short-term HFD on outcome of ischemia reperfusion injury. Two-week exposure to HFD did not worsen outcome of ischemia reperfusion (IR) injury in male B6D2F1 mice. A. Experimental design. Mice were fed a low fat control diet (C) or high fat diet (HFD) for 2 weeks prior to onset of renal or hepatic ischemia reperfusion injury, and then returned to the low fat control diet after surgery. Blood was drawn prior to injury or at the indicated times after reperfusion and analyzed for markers of renal function (urea) or liver injury (ALT) as indicated. B. Outcome of 25 minutes bilateral renal ischemia reperfusion injury as measured by changes in urea in serum prior to (time = 0) and on the indicated day after ischemia/reperfusion injury; (n=5/group). C. Outcome of 30 minutes hepatic ischemia reperfusion injury as measured by the amount of the liver enzyme ALT in serum prior to (time = 0) and at the indicated time after reperfusion; (n=5/group).

Figure 2

Influence of short-term protein free DR after HFD on outcome of ischemia reperfusion injury. A. Experimental design. Male B6D2F1 mice were fed a high fat diet for 2 weeks followed by 1 week of low fat control (C) vs. low fat protein free (PF) diet prior to onset of renal or hepatic IRI. All animals were returned to the low fat control diet after surgery. B. Outcome of 30 minutes bilateral renal IRI as measured by changes in serum urea and creatinine on the indicated day after injury; n=5/group. Below: representative images of hematoxylin/eosin stained kidney sections from the indicated groups harvested 3 days after injury. Arrows point to tubular structures in which cell death and disruption of normal structure is evident. G, glomerulus; scale bar = 20 µm. The percentage of tubular epithelial cell necrosis in the cortex and at the cortical-medullary junction in serial sections 100 µm apart from each kidney is quantitated at right; n=3/group.C. Outcome of 30 minutes hepatic ischemia reperfusion injury as measured by the amount of the liver enzymes ALT and AST in serum 3 and 24 hrs after reperfusion; n=15/group. Below: representative images of hematoxylin/eosin stained liver sections from the indicated group harvested 24 hrs after injury. Asterisk indicates the central vein associated with portal triads; eosinophilic regions are characteristic of cell necrosis. Scale bar = 100 µm. The average percentage of necrosis in 10 microscopic fields per animal is quantitated at right; n=6/group. Asterisks indicate the significance of the difference between groups at the indicated time point according to an unpaired, two-tailed Student’s T test; *p<0.05, ***p<0.001.

Figure 3

Influence of short-term HFD and/or fasting on intimal hyperplasia.A. Experimental design. Male C57BL/6J mice were exposed for two weeks to a high fat diet (HFD) or low-fat control diet (C) for the indicated period with or without a 3 day water-only fast immediately prior to focal stenosis. All mice were then returned to the control diet. Four weeks later, intimal hyperplasia (IH) was measured by histology. B, C. Intimal area, medial area, and intimal/medial area ratio at the indicated distance from the focal stenosis (n=10 mice/per group). P value indicates the significance of the difference between intimal areas of the indicated groups according to a two-way ANOVA. Note the absence of differences between HFD and control diets alone on intimal area. D. Representative Masson’s trichrome-stained images under each dietary condition taken at 0.8–1.2mm distance proximal to a focal stenosis. Yellow line depicts internal elastic lamina. Scale bars = 50 µm.

Figure 4

Influence of short-term protein free DR after HFD on intimal hyperplasia. A. Experimental design. Following two weeks on a high fat diet, male B6D2F1 animals were exposed for one week to a control diet with 18% calories from protein (C, n=10) or an isocaloric diet lacking protein (PF, n=10) prior to focal stenosis. All mice were then returned to control chow. Four weeks later, intimal hyperplasia (IH) was measured by histology. B. Intimal area, medial area, and intimal/medial area ratio at the indicated distance from the focal stenosis. P value indicates the significance of the difference between intimal areas of the indicated groups according to a two-way ANOVA.