The use of preoperative nutritional interventions to protect against hepatic ischemia-reperfusion injury

Can caloric restriction improve outcomes of elective surgeries?

Energy restriction (ER) is a nutrition method to reduce the amount of energy intake while maintaining adequate nutrition. In clinical medicine, applications of ER have been implicated in longevity, mortality, metabolic, immune, and psychological health. However, there are limited studies showing the clinical benefit of ER within the immediate surgical setting. A specific, clinically oriented summary of the potential applications of ER is needed to optimize surgery outcomes for patients. The purpose of this article is to examine how ER can be used for perioperative optimization to improve outcomes for the patient and surgeon. It will also explore how these outcomes can feasibly fit in with enhanced recovery after surgery protocols and can be used as a method for nutrition optimization in surgery. Despite evidence of caloric restriction improving outcomes in critically ill surgical patients, there is not enough evidence to conclude that ER, perioperatively across noncritically ill cohorts, improves postoperative morbidity and mortality in elective surgeries. Nevertheless, a contemporary account of how ER techniques may have a significant role in reducing risk factors of adverse surgical outcomes in this cohort, for example, by encouraging preoperative weight loss contributing to decreased operating times, is reviewed.

Cardiac damage following renal ischemia reperfusion injury increased with excessive consumption of high fat diet but enhanced the cardiac resistance to reperfusion stress in rat

Renal ischemia-reperfusion (IR) injury inflicts remote cardiac dysfunction. Studies on rats fed with a high-fat diet (HD) showed contradictory results: some demonstrated increased sensitivity of the heart and kidney to IR injury, while others reported resistance. In this study, we examined cardiac dysfunction and compromised cardiac tolerance associated with renal IR in HD and standard diet (SD) fed rats. Male Wistar rats fed with HD or SD diet for 16 weeks were subjected to either renal sham or IR protocol (bilateral clamping for 45 min and reperfusion for 24 h). The hearts isolated from these rats were further subjected to normal perfusion or IR procedure to study cardiac response. Renal IR surgery negatively affected cardiac function with substantial changes in the cardiac tissues, like mitochondrial dysfunction, elevated oxidative stress, and inflammation. HD-fed rat hearts exhibited hypertrophy at the end of 16 weeks, and the consequential impact on the heart was higher in the animals underwent renal IR surgery than with sham surgery. However, the IR induction in the isolated heart from renal sham or renal IR operation showed significant tissue injury resistance and better physiological recovery in HD-fed rats. However, in SD-fed rats, only hearts from renal IR-operated rats showed resistance to cardiac IR, whereas hearts from renal sham-operated rats were more susceptible to IR damage. The augmented IR resistance in the heart with prior renal surgery was due to preserved mitochondrial bioenergetics function, reduced oxidative stress, and activation of the PI3K/AKT signaling axis.

Fasting Intervention for Children With Unilateral Renal Tumors to Reduce Toxicity

Childhood renal tumors account for around 6% of all childhood cancers and 90% of these cases are Wilms tumor. In Europe, the SIOP-RTSG approach is considered standard of care and has resulted in five-year survival rates of over 90%. Efforts to decrease toxicity are now being pursued. Short-term fasting (STF), a short but strong reduction in calorie-intake, is associated with improved fitness, enhanced coping with acute physical stress and a lower risk of age-associated diseases. STF temporarily reduces growth to boost resilience, maintenance, and defense-mechanisms, by which toxic side-effects of (oxidative) damage and inflammation are largely prevented. Renal surgery for Wilms tumor carries a risk of acute kidney injury (AKI) and pediatric patients that had an episode of AKI are at increased risk for developing chronic renal disease. STF could mitigate surgery-induced stress and could further improve outcomes. We aim to investigate the effect of STF on renal function recovery after renal tumor surgery by conducting a single-center, prospective, randomized, non-blinded, intervention study. Children diagnosed with a unilateral renal tumor and opting for curative treatment are eligible for inclusion. The main study objective is to investigate the potential decrease in occurrence of AKI due to STF. Secondary objectives include renal function recovery, child's wellbeing, physical functioning, and feasibility of and adherence to STF in children with cancer.

Fasting before living-kidney donation: effect on donor well-being and postoperative recovery: study protocol of a multicenter randomized controlled trial

BACKGROUND

One of the main effectors on the quality of life of living-kidney donors is postoperative fatigue. Caloric restriction (CR) and short-term fasting (STF) are associated with improved fitness and increased resistance to acute stress. CR/STF increases the expression of cytoprotective genes, increases immunomodulation via increased anti-inflammatory cytokine production, and decreases the expression of pro-inflammatory markers. As such, nutritional preconditioning by CR or STF represents a non-invasive and cost-effective method that could mitigate the effects of acute surgery-induced stress and postoperative fatigue. To investigate whether preoperative STF contributes to a reduction in fatigue after living-kidney donation, a randomized clinical trial is indicated.

METHODS

We aim to determine whether 2.5 days of fasting reduces postoperative fatigue score in subjects undergoing living-kidney donation. In this randomized study, the intervention group will follow a preoperative fasting regime for 2.5 days with a low-dose laxative, while the control group will receive standard care. The main study endpoint is postoperative fatigue, 4 weeks after living-kidney donation. Secondary endpoints include the effect of preoperative fasting on postoperative hospital admission time, the feasibility of STF, and the postoperative recovery of donor and recipient kidney function. This study will provide us with knowledge of the feasibility of STF and confirm its effect on postoperative recovery.

DISCUSSION

Our study will provide clinically relevant information on the merits of caloric restriction for living-kidney donors and recipients. We expect to reduce the postoperative fatigue in living-kidney donors and improve the postoperative recovery of living-kidney recipients. It will provide evidence on the clinical merits and potential caveats of preoperative dietary interventions.

TRIAL REGISTRATION

Netherlands Trial Register NL9262 . EudraCT 2020-005445-16 . MEC Erasmus MC MEC-2020-0778. CCMO NL74623.078.21.

C-reactive protein rise in response to macronutrient deficit early in critical illness: sign of inflammation or mediator of infection prevention and recovery

PURPOSE

Withholding parenteral nutrition (PN) early in critical illness, late-PN, has shown to prevent infections despite a higher peak C-reactive protein (CRP). We investigated whether the accentuated CRP rise was caused by a systemic inflammatory effect mediated by cytokines or arose as a consequence of the different feeding regimens, and whether it related to improved outcome with late-PN.

METHODS

This secondary analysis of the EPaNIC-RCT first investigated, with multivariable linear regression analyses, determinants of late-PN-induced CRP rise and its association with cytokine responses (IL-6, IL-10, TNF-α) in matched early-PN and late-PN patients requiring intensive care for ≥ 3 days. Secondly, with multivariable logistic regression and Cox proportional-hazard analyses, we investigated whether late-PN-induced CRP rises mediated infection prevention and enhanced recovery or reflected an adverse effect counteracting such benefits of late-PN.

RESULTS

CRP peaked on day 3, higher with late-PN [216(152-274)mg/l] (n = 946) than with early-PN [181(122-239)mg/l] (n = 946) (p < 0.0001). Independent determinants of higher CRP rise were lower carbohydrate and protein intakes (p ≤ 0.04) with late-PN, besides higher blood glucose and serum insulin concentrations (p ≤ 0.01). Late-PN did not affect cytokines. Higher CRP rises were independently associated with more infections and lower likelihood of early ICU discharge (p ≤ 0.002), and the effect size of late-PN versus early-PN on these outcomes was increased rather than reduced after adjusting for CRP rise, not confirming a mediating role.

CONCLUSIONS

The higher CRP rise with late-PN, explained by the early macronutrient deficits, did not relate to cytokine responses and thus did not reflect more systemic inflammation. Instead of mediating clinical benefit on infection or recovery, the accentuated CRP rise appeared an adverse effect reducing such late-PN benefits.

The gut microbial metabolite, 3,4-dihydroxyphenylpropionic acid, alleviates hepatic ischemia/reperfusion injury via mitigation of macrophage pro-inflammatory activity in mice

Hepatic ischemia/reperfusion injury (HIRI) is a serious complication that occurs following shock and/or liver surgery. Gut microbiota and their metabolites are key upstream modulators of development of liver injury. Herein, we investigated the potential contribution of gut microbes to HIRI. Ischemia/reperfusion surgery was performed to establish a murine model of HIRI. 16S rRNA gene sequencing and metabolomics were used for microbial analysis. Transcriptomics and proteomics analysis were employed to study the host cell responses. Our results establish HIRI was significantly increased when surgery occurred in the evening (ZT12, 20:00) when compared with the morning (ZT0, 08:00); however, antibiotic pretreatment reduced this diurnal variation. The abundance of a microbial metabolite 3,4-dihydroxyphenylpropionic acid was significantly higher in ZT0 when compared with ZT12 in the gut and this compound significantly protected mice against HIRI. Furthermore, 3,4-dihydroxyphenylpropionic acid suppressed the macrophage pro-inflammatory response in vivo and in vitro. This metabolite inhibits histone deacetylase activity by reducing its phosphorylation. Histone deacetylase inhibition suppressed macrophage pro-inflammatory activation and diminished the diurnal variation of HIRI. Our findings revealed a novel protective microbial metabolite against HIRI in mice. The potential underlying mechanism was at least in part, via 3,4-dihydroxyphenylpropionic acid-dependent immune regulation and histone deacetylase (HDAC) inhibition in macrophages.

Fasting and fasting-mimicking diets for chemotherapy augmentation

The increasingly older population in most developed countries will likely experience aging-related chronic diseases such as diabetes, metabolic syndrome, heart and lung diseases, osteoporosis, arthritis, dementia, and/or cancer. Genetic and environmental factors, but also lifestyle choices including physical activity and dietary habits, play essential roles in disease onset and progression. Sixty-five percent of Americans diagnosed with cancer now survive more than 5 years, making the need for informed lifestyle choices particularly important to successfully complete their treatment, increase the recovery from the cytotoxic therapy options, and improve cancer-free survival. This review will discuss the findings on the use of prolonged fasting, as well as fasting-mimicking diets to augment cancer treatment. Preclinical studies in rodents strongly support the implementation of these dietary interventions and a small number of clinical trials begin to provide encouraging results for cancer patients and cancer survivors.

How Far Are We from Prescribing Fasting as Anticancer Medicine?

(1) Background: the present review provides a comprehensive and up-to date overview of the potential exploitation of fasting as an anticancer strategy. The rationale for this concept is that fasting elicits a differential stress response in the setting of unfavorable conditions, empowering the survival of normal cells, while killing cancer cells. (2) Methods: the present narrative review presents the basic aspects of the hormonal, molecular, and cellular response to fasting, focusing on the interrelationship of fasting with oxidative stress. It also presents nonclinical and clinical evidence concerning the implementation of fasting as adjuvant to chemotherapy, highlighting current challenges and future perspectives. (3) Results: there is ample nonclinical evidence indicating that fasting can mitigate the toxicity of chemotherapy and/or increase the efficacy of chemotherapy. The relevant clinical research is encouraging, albeit still in its infancy. The path forward for implementing fasting in oncology is a personalized approach, entailing counteraction of current challenges, including: (i) patient selection; (ii) fasting patterns; (iii) timeline of fasting and refeeding; (iv) validation of biomarkers for assessment of fasting; and (v) establishment of protocols for patients’ monitoring. (4) Conclusion: prescribing fasting as anticancer medicine may not be far away if large randomized clinical trials consolidate its safety and efficacy.

Dietary restriction for prevention of contrast-induced acute kidney injury in patients undergoing percutaneous coronary angiography: a randomized controlled trial

Short-term dietary restriction (DR) may prevent organ damage from ischemic or toxic insults in animals, but clear evidence in humans is missing. While especially intraarterial administration of contrast media represents a cause of hospital-acquired acute kidney injury (AKI), targeted preventive strategies are not available. This trial investigated the feasibility and effectiveness of pre-interventional DR for preventing AKI in patients undergoing percutaneous coronary intervention (PCI). Patients were randomized to receive a formula diet containing 60% of daily energy requirement (DR group) or ad-libitum food during the 4-day-interval before PCI. Primary endpoint was change of serum creatinine 48 h after PCI (Δcreatinine). Further analyses included incidence of AKI and safety evaluation. Δcreatinine post PCI in the DR group vs. the control group did not show any difference (DR: 0.03(-0.15,0.14)mg/dL vs. control: 0.09(-0.03,0.22)mg/dL;p = 0.797). Subgroup analyses revealed a significant beneficial impact of DR in patients that received ≤100 ml of contrast agent (DR n = 26: Δcreatinine -0.03(-0.20,0.08)mg/dL vs. control n = 24: Δcreatinine 0.10(-0.08,0.24)mg/dL; p = 0.041) and in patients with ≤2 risk factors for AKI (DR: n = 27; Δcreatinine -0.01(-0.18,0.07)mg/dL vs. control n = 31: Δcreatinine 0.09(-0.03,0.16)mg/dl; p = 0.030). Although the primary endpoint was not met, the results of this trial suggest a beneficial impact of DR in low-to-moderate risk patients.

Current Knowledge about the Effect of Nutritional Status, Supplemented Nutrition Diet, and Gut Microbiota on Hepatic Ischemia-Reperfusion and Regeneration in Liver Surgery

Ischemia-reperfusion (I/R) injury is an unresolved problem in liver resection and transplantation. The preexisting nutritional status related to the gut microbial profile might contribute to primary non-function after surgery. Clinical studies evaluating artificial nutrition in liver resection are limited. The optimal nutritional regimen to support regeneration has not yet been exactly defined. However, overnutrition and specific diet factors are crucial for the nonalcoholic or nonalcoholic steatohepatitis liver diseases. Gut-derived microbial products and the activation of innate immunity system and inflammatory response, leading to exacerbation of I/R injury or impaired regeneration after resection. This review summarizes the role of starvation, supplemented nutrition diet, nutritional status, and alterations in microbiota on hepatic I/R and regeneration. We discuss the most updated effects of nutritional interventions, their ability to alter microbiota, some of the controversies, and the suitability of these interventions as potential therapeutic strategies in hepatic resection and transplantation, overall highlighting the relevance of considering the extended criteria liver grafts in the translational liver surgery.

β-hydroxybutyrate attenuates renal ischemia-reperfusion injury through its anti-pyroptotic effects

Ketone bodies including β-hydroxybutyrate (β-OHB) have been shown to protect against ischemic tissue injury when present at low concentrations. We evaluated the impact of β-OHB on renal ischemia/reperfusion injury (IRI). Mice were treated with a continuous infusion of β-OHB using an osmotic mini-pump before and after IRI. We also tested the effects of increasing endogenous serum β-OHB levels by fasting. Renal IRI was attenuated by β-OHB treatment compared to saline control, with similar results in the fasting condition. β-OHB treatment reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and increased expression of forkhead transcription factor O3 (FOXO3), an upstream regulator of pyroptosis. Although β-OHB treatment did not impact markers of apoptosis, it decreased the expression of caspase-1 and proinflammatory cytokines, indicating that β-OHB blocked pyroptosis. In a human proximal tubular cell line exposed to hypoxia and reoxygenation, β-OHB reduced cell death in a FOXO3-dependent fashion. Histone acetylation was decreased in kidneys exposed to IRI and in proximal tubular cells exposed to hypoxia and reoxygenation, and this effect was ameliorated by β-OHB through the inactivation of histone deacetylases. In vitro, β-OHB treatment restored histone acetylation at the FOXO3 promoter. Consistent with epigenetic molecular effects, the renoprotective effects of β-OHB were still observed when the continuous infusion was stopped at the time of IRI. Thus, β-OHB attenuates renal IRI through anti-pyroptotic effects, likely mediated by an epigenetic effect on FOXO3 expression.

Model-based virtual patient analysis of human liver regeneration predicts critical perioperative factors controlling the dynamic mode of response to resection

BACKGROUND

Liver has the unique ability to regenerate following injury, with a wide range of variability of the regenerative response across individuals. Existing computational models of the liver regeneration are largely tuned based on rodent data and hence it is not clear how well these models capture the dynamics of human liver regeneration. Recent availability of human liver volumetry time series data has enabled new opportunities to tune the computational models for human-relevant time scales, and to predict factors that can significantly alter the dynamics of liver regeneration following a resection.

METHODS

We utilized a mathematical model that integrates signaling mechanisms and cellular functional state transitions. We tuned the model parameters to match the time scale of human liver regeneration using an elastic net based regularization approach for identifying optimal parameter values. We initially examined the effect of each parameter individually on the response mode (normal, suppressed, failure) and extent of recovery to identify critical parameters. We employed phase plane analysis to compute the threshold of resection. We mapped the distribution of the response modes and threshold of resection in a virtual patient cohort generated in silico via simultaneous variations in two most critical parameters.

RESULTS

Analysis of the responses to resection with individual parameter variations showed that the response mode and extent of recovery following resection were most sensitive to variations in two perioperative factors, metabolic load and cell death post partial hepatectomy. Phase plane analysis identified two steady states corresponding to recovery and failure, with a threshold of resection separating the two basins of attraction. The size of the basin of attraction for the recovery mode varied as a function of metabolic load and cell death sensitivity, leading to a change in the multiplicity of the system in response to changes in these two parameters.

CONCLUSIONS

Our results suggest that the response mode and threshold of failure are critically dependent on the metabolic load and cell death sensitivity parameters that are likely to be patient-specific. Interventions that modulate these critical perioperative factors may be helpful to drive the liver regenerative response process towards a complete recovery mode.

Nuclear DNA Damage and Ageing

Although the links between defects in DNA repair and cancer are well established, an accumulating body of evidence suggests a series of functional links between genome maintenance pathways, lifespan regulation mechanisms and age-related diseases in mammals. Indeed, the growing number of DNA repair-deficient patients with progeria suggests that persistent DNA damage and genome caretakers are tightly linked to lifespan regulating circuits and age-related diseases. Here, we discuss the impact of irreparable DNA damage events in mammalian physiology highlighting the relevance of DNA repair factors in mammalian development and aging.

Protective effects of short-term dietary restriction in surgical stress and chemotherapy

Reduced caloric intake including fasting, as well as the dietary composition or the timing of food intake, impact longevity, likely through a modification in the onset or the severity of chronic aging-related diseases such as cancer. As with pre- and post-operative dietary recommendations, evidence-based nutritional advice from healthcare professionals during and after cancer treatment is often vague or conflicting. We hypothesize that preventive dietary recommendations can help in the context of both chronic cancer treatment efficacy and the avoidance of development of secondary malignancies, as well as in the context of protection from the acute stress of surgery. In this perspective review, we will discuss the latest findings on the potential role of short-term dietary restriction in cancer treatment and improvement of surgical outcome.

Fasting and Caloric Restriction in Cancer Prevention and Treatment

Cancer is the second leading cause of death in the USA and among the leading major diseases in the world. It is anticipated to continue to increase because of the growth of the aging population and prevalence of risk factors such as obesity, smoking, and/or poor dietary habits. Cancer treatment has remained relatively similar during the past 30 years with chemotherapy and/or radiotherapy in combination with surgery remaining the standard therapies although novel therapies are slowly replacing or complementing the standard ones. According to the American Cancer Society, the dietary recommendation for cancer patients receiving chemotherapy is to increase calorie and protein intake. In addition, there are no clear guidelines on the type of nutrition that could have a major impact on cancer incidence. Yet, various forms of reduced caloric intake such as calorie restriction (CR) or fasting demonstrate a wide range of beneficial effects able to help prevent malignancies and increase the efficacy of cancer therapies. Whereas chronic CR provides both beneficial and detrimental effects as well as major compliance challenges, periodic fasting (PF), fasting-mimicking diets (FMDs), and dietary restriction (DR) without a reduction in calories are emerging as interventions with the potential to be widely used to prevent and treat cancer. Here, we review preclinical and preliminary clinical studies on dietary restriction and fasting and their role in inducing cellular protection and chemotherapy resistance.

Hibernation reduces cellular damage caused by warm hepatic ischemia-reperfusion in ground squirrels

During the hibernation season, livers from 13-lined ground squirrels (Ictidomys tridecemlineatus) are resistant to damage induced by ex vivo, cold ischemia-warm reperfusion (IR) compared with livers from summer squirrels or rats. Here, we tested the hypothesis that hibernation also reduces damage to ground squirrel livers in an in vivo, warm IR model, which more closely resembles complications associated with traumatic injury or surgical interventions. We also examined whether protection is mediated by two metabolites, inosine and biliverdin, that are elevated in ground squirrel liver during interbout arousals. Active squirrels in spring and hibernators during natural arousals to euthermia (body temperature 37 °C) were subject to liver IR or sham treatments. A subset of hibernating squirrels was pre-treated with compounds that inhibit inosine synthesis/signaling or biliverdin production. This model of liver IR successfully induced hepatocellular damage as indicated by increased plasma liver enzymes (ALT, AST) and hepatocyte apoptosis index compared to sham in both seasons, with greater elevations in spring squirrels. In addition, liver congestion increased after IR to a similar degree in spring and hibernating groups. Microvesicular steatosis was not affected by IR within the same season but was greater in sham squirrels in both seasons. Plasma IL-6 increased ~twofold in hibernators pre-treated with a biliverdin synthesis inhibitor (SnPP) prior to IR, but was not altered by IR in untreated squirrels. The results show that hibernation provides protection to ground squirrel livers subject to warm IR. Further research is needed to clarify mechanisms responsible for endogenous protection of liver tissue under ischemic stress.

Fasting protects against the side effects of irinotecan treatment but does not affect anti-tumour activity in mice

BACKGROUND

The main limitation to the use of irinotecan in the treatment of colorectal cancer is the severity of side effects, including neutropaenia and diarrhoea. Here, we explored the effects of 3 days of fasting on irinotecan-induced toxicities, on plasma, liver and tumour pharmacokinetics and on anti-tumour activity in mice.

EXPERIMENTAL APPROACH

Male BALB/c mice received C26 colon carcinoma cells subcutaneously. They were randomized 1:1 into equally sized ad libitum fed and fasted groups after which they were treated with irinotecan. Weight and adverse side effects were recorded daily. At the end of the experiment, tumours were resected and weighed, and concentrations of irinotecan and its active metabolite SN-38 were determined in plasma and tumour.

KEY RESULTS

Fasting prevented the diarrhoea and visible signs of discomfort induced by irinotecan. Ad libitum fed animals developed leucopenia compared with untreated controls, whereas fasted mice did not. Irinotecan suppressed tumour growth equally in both treated groups, compared with untreated controls. Levels of the active irinotecan metabolite SN-38 9 (calculated as AUC values) were significantly lower in fasted mice in both plasma and liver, but not in tumour tissue.

CONCLUSIONS AND IMPLICATIONS

Fasting protected against irinotecan-induced side effects without interfering with its anti-tumour efficacy. Fasting induced a lower systemic exposure to SN-38, which may explain the absence of adverse side effects, while tumour levels of SN-38 remained unchanged. These data offer important new approaches to improve treatment with irinotecan in patients.

Fasting protects against the side effects of irinotecan but preserves its anti-tumor effect in Apc15lox mutant mice

Irinotecan is a widely used topoisomerase-I-inhibitor with a very narrow therapeutic window because of its severe toxicity. In the current study we have examined the effects of fasting prior to irinotecan treatment on toxicity and anti-tumor activity. FabplCre;Apc(15lox/+) mice, which spontaneously develop intestinal tumors, of 27 weeks of age were randomized into 3-day fasted and ad libitum fed groups, followed by treatment with a flat-fixed high dose of irinotecan or vehicle. Side-effects were recorded until 11 days after the start of the experiment. Tumor size, and markers for cell-cycle activity, proliferation, angiogenesis, and senescence were measured. Fasted mice were protected against the side-effects of irinotecan treatment. Ad libitum fed mice developed visible signs of discomfort including weight loss, lower activity, ruffled coat, hunched-back posture, diarrhea, and leukopenia. Irinotecan reduced tumor size in fasted and ad libitum fed groups similarly compared to untreated controls (2.4 ± 0.67 mm and 2.4 ± 0.82 mm versus 3.0 ± 1.05 mm and 2.8 ± 1.08 mm respectively, P < 0.001). Immunohistochemical analysis showed reduced proliferation, a reduced number of vascular endothelial cells, and increased levels of senescence in tumors of both irinotecan treated groups. In conclusion, 3 days of fasting protects against the toxic side-effects of irinotecan in a clinically relevant mouse model of spontaneously developing colorectal cancer without affecting its anti-tumor activity. These results support fasting as a powerful way to improve treatment of colorectal carcinoma patients.

Preoperative fasting protects against renal ischemia-reperfusion injury in aged and overweight mice

Ischemia-reperfusion injury (IRI) is inevitable during kidney transplantation leading to oxidative stress and inflammation. We previously reported that preoperative fasting in young-lean male mice protects against IRI. Since patients are generally of older age with morbidities possibly leading to a different response to fasting, we investigated the effects of preoperative fasting on renal IRI in aged-overweight male and female mice. Male and female F1-FVB/C57BL6-hybrid mice, average age 73 weeks weighing 47.2 grams, were randomized to preoperative ad libitum feeding or 3 days fasting, followed by renal IRI. Body weight, kidney function and survival of the animals were monitored until day 28 postoperatively. Kidney histopathology was scored for all animals and gene expression profiles after fasting were analyzed in kidneys of young and aged male mice. Preoperative fasting significantly improved survival after renal IRI in both sexes compared with normal fed mice. Fasted groups had a better kidney function shown by lower serum urea levels after renal IRI. Histopathology showed less acute tubular necrosis and more regeneration in kidneys from fasted mice. A mRNA analysis indicated the involvement of metabolic processes including fatty acid oxidation and retinol metabolism, and the NRF2-mediated stress response. Similar to young-lean, healthy male mice, preoperative fasting protects against renal IRI in aged-overweight mice of both genders. These findings suggest a general protective response of fasting against renal IRI regardless of age, gender, body weight and genetic background. Therefore, fasting could be a non-invasive intervention inducing increased oxidative stress resistance in older and overweight patients as well.

Metabolic regulation of Sirtuins upon fasting and the implication for cancer

PURPOSE OF REVIEW

The purpose of this review is to highlight recent studies on mammalian sirtuins that coordinately regulate cellular metabolic homeostasis upon fasting and to summarize the beneficial effects of fasting on carcinogenesis and cancer therapy.

RECENT FINDINGS

Recent studies have demonstrated that fasting may protect normal cells and mice from the metabolic conditions that are harmful as well as decrease the incidence of carcinogenesis. Fasting could also slow the tumor growth and augment the efficacy of certain systemic agents/chemotherapy drugs in various cancers. The mechanism behind this proposed idea may be due to, at least in some part, the metabolic regulation by Sirtuin family proteins whose functions are involved in specific aspects of longevity, stress response and metabolism. Sirtuins, particularly SIRT1 and SIRT3, can be activated by fasting and further exhibit their effects in insulin response, antioxidant defense, and glycolysis. Therefore, sirtuins may have anticancer effects by shifting metabolism to a less proliferative cell phenotype as well as less prone to oxidative stress attack.

SUMMARY

The in-depth understanding of the essential role of sirtuins in fasting process may have significant implications in developing a new metabolic diagram of cancer prevention or treatment.

Continuous administration of enteral lipid- and protein-rich nutrition limits inflammation in a human endotoxemia model

OBJECTIVE

An overzealous inflammatory response is an important cause of morbidity and mortality in surgical, trauma, and critically ill patients. Enteral administration of lipid-rich nutrition was previously shown to attenuate inflammation and reduce organ damage via a cholecystokinin-1 receptor-mediated vagovagal reflex in animal studies. The current preclinical study investigates the immunomodulatory potential of a custom-made enteral nutrition during systemic inflammation in man.

DESIGN

Double-blind, randomized controlled trial.

SETTING

Intensive care research unit.

SUBJECTS

Male volunteers.

INTERVENTIONS

After an overnight fast, 18 healthy male subjects received an IV bolus of Escherichia coli lipopolysaccharide (2 ng/kg). Subjects in the fasted group (n = 6) were deprived of food throughout the study, while subjects in the intervention groups were fed either custom-made lipid- and protein-rich nutrition (n = 6) or isocaloric control nutrition (n = 6) via nasojejunal tube, starting 1 hour prior to lipopolysaccharide administration until 6 hours afterward.

MEASUREMENTS AND MAIN RESULTS

Bolus lipopolysaccharide administration resulted in a marked inflammatory response. Continuous postpyloric administration of nutrition significantly increased plasma cholecystokinin levels throughout the lipopolysaccharide-induced inflammatory response. Lipid- and protein-rich nutrition attenuated circulating levels of the proinflammatory cytokines tumor necrosis factor-α and interleukin-6 and the interleukin-1 receptor antagonist compared with control nutrition (all p < 0.05) and fasted subjects (all p < 0.05). In additional, lipid- and protein-rich nutrition augmented the anti-inflammatory response, reflected by increased plasma levels of interleukin-10 compared with fasted subjects (p < 0.0001).

CONCLUSIONS

The current preclinical study expands the immunomodulating effects of enteral nutrition as previously observed in rodents to man. Continuous administration of enteral nutrition resulted in a rapid anti-inflammatory effect. Furthermore, enrichment of the nutritional composition with lipid and protein was shown to enhance the anti-inflammatory potential. Therefore, continuous enteral administration of lipid- and protein-rich nutrition is a promising intervention to modulate the immune response in the early course of systemic inflammation in man.

Preoperative diet impacts the adipose tissue response to surgical trauma

BACKGROUND

Short-term changes in preoperative nutrition can have profound effects on surgery-related outcomes such as ischemia/reperfusion injury in preclinical models. Dietary interventions that lend protection against stress in animal models (eg, fasting, dietary restriction [DR]) impact adipose tissue quality/quantity. Adipose tissue holds high surgical relevance because of its anatomic location and large tissue volume, and it is ubiquitously traumatized during surgery. Yet the response of adipose tissue to trauma under clinically relevant circumstances including dietary status remains poorly defined. We hypothesized that preoperative diet alters the adipose tissue response to surgical trauma.

METHODS

A novel mouse model of adipose tissue surgical trauma was employed. Dietary conditions (diet-induced obesity [DIO], preoperative DR) were modulated before application of surgical adipose tissue trauma in the context of clinically common scenarios (different ages, simulated bacterial wound contamination). Local/distant adipose tissue phenotypic responses were measured as represented by gene expression of inflammatory, tissue remodeling/growth, and metabolic markers.

RESULTS

Surgical trauma had a profound effect on adipose tissue phenotype at the site of trauma. Milder but significant distal effects on non-traumatized adipose tissue were also observed. DIO exacerbated the inflammatory aspects of this response, and preoperative DR tended to reverse these changes. Age and lipopolysaccharide (LPS)-simulated bacterial contamination also impacted the adipose tissue response to trauma, with young adult animals and LPS treatment exacerbating the proinflammatory response.

CONCLUSION

Surgical trauma dramatically impacts both local and distal adipose tissue biology. Short-term preoperative DR may offer a strategy to attenuate this response.

NRF2 and the Phase II Response in Acute Stress Resistance Induced by Dietary Restriction

Dietary restriction (DR) as a means to increase longevity is well-established in a number of model organisms from yeast to primates. DR also improves metabolic fitness and increases resistance to acute oxidative, carcinogenic and toxicological stressors - benefits with more immediate potential for clinical translation than increased lifespan. While the detailed mechanism of DR action remains unclear, a conceptual framework involving an adaptive, or hormetic response to the stress of nutrient/energy deprivation has been proposed. A key prediction of the hormesis hypothesis of DR is that beneficial adaptations occur in response to an increase in reactive oxygen/nitrogen species (ROS). These ROS may be derived either from increased mitochondrial respiration or increased xenobiotic metabolism in the case of some DR mimetics. This review will focus on the potential role of the redox-sensing transcription factor NF-E2-related factor 2 (NRF2) and its control of the evolutionarily conserved antioxidant/redox cycling and detoxification systems, collectively known as the Phase II response, in the adaptive response to DR.

Starvation, detoxification, and multidrug resistance in cancer therapy

The selection of chemotherapy drugs is based on the cytotoxicity to specific tumor cell types and the relatively low toxicity to normal cells and tissues. However, the toxicity to normal cells poses a major clinical challenge, particularly when malignant cells have acquired resistance to chemotherapy. This drug resistance of cancer cells results from multiple factors including individual variation, genetic heterogeneity within a tumor, and cellular evolution. Much progress in the understanding of tumor cell resistance has been made in the past 35 years, owing to milestone discoveries such as the identification and characterization of ABC transporters. Nonetheless, the complexity of the genetic and epigenetic rewiring of cancer cells makes drug resistance an equally complex phenomenon that is difficult to overcome. In this review, we discuss how the remarkable changes in the levels of glucose, IGF-I, IGFBP-1 and in other proteins caused by fasting have the potential to improve the efficacy of chemotherapy against tumors by protecting normal cells and tissues and possibly by diminishing multidrug resistance in malignant cells.

Preoperative fasting protects mice against hepatic ischemia/reperfusion injury: mechanisms and effects on liver regeneration

We show that brief periods of fasting induce functional changes similar to those induced by long-term dietary restriction in mice, and these changes include protection from ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanisms of protection induced by fasting, and we determined the effect on liver regeneration after partial hepatectomy. Partial hepatic ischemia (75 minutes) was induced in ad libitum fed mice and in 1- to 3-day-fasted mice, and one-third or two-thirds hepatectomy was performed in ad libitum fed mice and 3-day-fasted mice. Preoperative fasting for 2 or 3 days significantly decreased hepatocellular I/R injury. Hepatic gene expression of heme oxygenase 1 (HO-1), superoxide dismutase 2 (SOD2), glutathione peroxidase 1 (Gpx1), and glutathione reductase (GSR) was significantly up-regulated in 3-day-fasted mice at the baseline and 6 hours after reperfusion. After reperfusion, p-selectin and interleukin-6 (IL-6) levels were significantly lower, and superoxide radical generation, lipid peroxidation, and neutrophil influx were significantly attenuated in 3-day-fasted mice. Preoperative fasting did not affect liver regeneration after one-third hepatectomy. Hepatic gene expression of IL-6 and transforming growth factor β1 was significantly higher in 3-day-fasted mice before and after one-third hepatectomy. Tumor necrosis factor α expression significantly increased after one-third hepatectomy in 3-day-fasted mice. After a 3-day fast and two-thirds hepatectomy, liver regeneration and subsequent postoperative recovery were compromised. In conclusion, up-regulation of the stress response gene HO-1 and the antioxidant enzymes SOD2, Gpx1, and GSR at the baseline and a better response after reperfusion likely underlie the protection induced by fasting against hepatic I/R injury. Preoperative fasting may be a promising new strategy for protecting the liver against I/R injury during liver transplantation and minor liver resections, although its effect on extended hepatectomy warrants further exploration.

Fasting vs dietary restriction in cellular protection and cancer treatment: from model organisms to patients

The dietary recommendation for cancer patients receiving chemotherapy, as described by the American Cancer Society, is to increase calorie and protein intake. Yet, in simple organisms, mice, and humans, fasting--no calorie intake--induces a wide range of changes associated with cellular protection, which would be difficult to achieve even with a cocktail of potent drugs. In mammals, the protective effect of fasting is mediated, in part, by an over 50% reduction in glucose and insulin-like growth factor 1 (IGF-I) levels. Because proto-oncogenes function as key negative regulators of the protective changes induced by fasting, cells expressing oncogenes, and therefore the great majority of cancer cells, should not respond to the protective signals generated by fasting, promoting the differential protection (differential stress resistance) of normal and cancer cells. Preliminary reports indicate that fasting for up to 5 days followed by a normal diet, may also protect patients against chemotherapy without causing chronic weight loss. By contrast, the long-term 20 to 40% restriction in calorie intake (dietary restriction, DR), whose effects on cancer progression have been studied extensively for decades, requires weeks-months to be effective, causes much more modest changes in glucose and/or IGF-I levels, and promotes chronic weight loss in both rodents and humans. In this study, we review the basic as well as clinical studies on fasting, cellular protection and chemotherapy resistance, and compare them to those on DR and cancer treatment. Although additional pre-clinical and clinical studies are necessary, fasting has the potential to be translated into effective clinical interventions for the protection of patients and the improvement of therapeutic index.

Preoperative fasting induced protection against renal ischemia/reperfusion injury is independent of ghrelin in mice

One of the factors negatively influencing the outcome after kidney transplantation is ischemia-reperfusion (I/R) injury. Preoperative fasting is able to confer protection against I/R injury. We hypothesized that the protection imposed by preoperative fasting is mediated by increased levels of acylated ghrelin. Male C57BL/6 mice, 10 to 12 weeks old, were fasted for 1, 2, or 3 days, after which, acylated ghrelin levels were determined. Ad libitum fed mice were injected with acylated ghrelin or phosphate-buffered saline before renal I/R injury. Furthermore, mice were fasted for 3 days during which they were injected with a growth hormone secretagogue receptor antagonist, to block the effects of ghrelin, or a vehiculum. Bilateral renal I/R injury was induced by clamping the artery and vein of the left and right kidney simultaneously for 37 minutes. Kidney function was assessed by means of serum urea values determined at 24 and 48 hours after reperfusion. Fasting significantly increased acylated ghrelin serum levels. Ghrelin suppletion in ad libitum fed animals or ghrelin receptor blockade in fasted animals did not affect renal function after I/R injury. Our data suggest that the increased levels of acylated ghrelin induced by fasting do not mediate its protection against renal I/R injury.

Pre-operative dietary restriction is feasible in live-kidney donors

Dietary restriction (DR), defined as reduced energy intake without malnutrition, confers protection against renal ischemia and reperfusion injury in animal models. This pilot study investigates for the first time the feasibility of pre-operative DR in the clinical setting. Live-kidney donors were randomized between pre-operative DR or ad libitum intake. Seventeen participants were instructed to follow a 30% calorie-restricted diet, followed by one day of water-only fasting prior to surgery. Thirteen participants were allowed to eat ad libitum pre-operatively. Ninety-four percent of the donors adhered to the diet, 31.4% reduction in caloric intake was achieved. Post-operative well-being, appetite and ability to perform daily tasks were not different between both groups. There was no difference in post-transplant graft function of kidneys obtained from DR donors or control donors as determined by serum creatinine levels during the first post-operative month and renograms at post-operative day one. This study shows that mild dietary restriction is feasible in the setting of live-kidney donation. No effect was observed regarding post-operative graft function. Additional studies are warranted to investigate the appropriate regimen of dietary restriction to protecting against ischemia and reperfusion injury, such as increasing the magnitude and/or duration of the reduction in daily caloric intake.

Dietary restriction modifies certain aspects of the postoperative acute phase response

BACKGROUND

Lifespan extension is achieved through long-term application of dietary restriction (DR), and benefits of short-term dietary restriction on acute stress and inflammation have been observed. So far, the effects of short-term DR in humans are relatively unknown. We hypothesized that short-term DR in humans reduces the acute phase response following a well defined surgical trauma.

METHODS

Thirty live kidney donors were randomized between 30% preoperative dietary restriction followed by 1 d of fasting (n=17) or a 4 d ad libitum regimen (n=13) prior to surgery. Leukocyte subsets and numbers and serum cytokine levels were determined. Whole blood was stimulated with lipopolysaccharide (LPS) and cytokine production was determined.

RESULTS

A clear trend towards lower numbers of postoperative circulating leukocytes was observed in the DR group. IL-8 serum levels were significantly higher in the DR group over the first 6 postoperative d (P=0.018). After LPS stimulation, significantly less TNF-α (P=0.001) was produced by blood obtained postoperatively compared with preoperative blood from the DR group. This was not observed in the control group.

CONCLUSIONS

A relatively short preoperative dietary restriction regimen was able to modify certain aspects of the postoperative acute phase response. These data warrant further studies into the dietary conditions that improve stress resistance in humans. (Dutch Trial Registry number: NTR1875).