Cysteine/cystine-rich undenatured whey protein supplement in patients' pressure ulcers outcomes: an open label study

Nutritional interventions for preventing and treating pressure ulcers

BACKGROUND

Pressure ulcers are localized injuries to the skin or the underlying tissue, or both, and are common in older and immobile people, people with diabetes, vascular disease, or malnutrition, as well as those who require intensive or palliative care. People with pressure ulcers often suffer from severe pain and exhibit social avoidance behaviours. The prevention and treatment of pressure ulcers involves strategies to optimize hydration, circulation, and nutrition. Adequate nutrient intake can reduce the risk factor of malnutrition and promote wound healing in existing pressure ulcers. However, it is unclear which nutrients help prevent and treat pressure ulcers. This is an update of an earlier Cochrane Review.

OBJECTIVES

To evaluate the benefits and harms of nutritional interventions (special diets, supplements) for preventing and treating pressure ulcers in people with or without existing pressure ulcers compared to standard diet or other nutritional interventions.

SEARCH METHODS

We used extensive Cochrane search methods. The latest search was in May 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in people with or without existing pressure ulcers, that compared nutritional interventions aimed at preventing or treating pressure ulcers with standard diet or other types of nutritional interventions.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcome for prevention studies was the proportion of participants who developed new (incident) pressure ulcers. For treatment studies, our primary outcomes were time to complete pressure ulcer healing, number of people with healed pressure ulcers, size and depth of pressure ulcers, and rate of pressure ulcer healing. Secondary outcomes were side effects, costs, health-related quality of life and acceptability. We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We included 33 RCTs with 7920 participants. Data for meta-analysis were available from 6993 participants. Pressure ulcer prevention Eleven studies (with 12 arms) compared six types of nutritional interventions for the prevention of pressure ulcers. Compared to standard diet, energy, protein and micronutrient supplements may result in little to no difference in the proportion of participants developing a pressure ulcer (energy, protein and micronutrient supplements 248 per 1000, standard diet 269 per 1000; RR 0.92, 95% CI 0.71 to 1.19; 3 studies, 1634 participants; low-certainty evidence). Compared to standard diet, protein supplements may result in little to no difference in pressure ulcer incidence (protein 21 per 1000, standard diet 28 per 1000; RR 0.75, 95% CI 0.49 to 1.14; 4 studies, 4264 participants; low-certainty evidence). The evidence is very uncertain about the gastrointestinal side effects of these supplements (protein 109 per 1000, standard diet 155 per 1000; RR 0.70, 95% CI 0.06 to 7.96; 2 studies, 140 participants, very low-certainty evidence). The evidence is very uncertain about the effects of protein, arginine, zinc and antioxidants; L-carnitine, L-leucine, calcium, magnesium and vitamin D; EPA, GLA and antioxidants; disease-specific supplements on pressure ulcer incidence when compared to standard diet (1 study each; very low-certainty evidence for all comparisons). Pressure ulcer treatment Twenty-four studies (with 27 arms) compared 10 types of nutritional interventions or supplements for treatment of pressure ulcers. Compared to standard diet, energy, protein and micronutrient supplements may slightly increase the number of healed pressure ulcers (energy, protein and micronutrients 366 per 1000, standard diet 253 per 1000; RR 1.45, 95% CI 1.14 to 1.85; 3 studies, 577 participants, low-certainty evidence). The evidence is very uncertain about the effect of these supplements on gastrointestinal side effects. Compared to standard diet, the evidence is very uncertain about the effect of protein, arginine, zinc and antioxidant supplements on pressure ulcer healing (pressure ulcer area: mean difference (MD) 2 cm² smaller, 95% CI 4.54 smaller to 0.53 larger; 2 studies, 71 participants, very low-certainty evidence). The evidence on side effects of these supplements is very uncertain. Compared to standard diet, supplements with arginine and micronutrients may not increase the number of healed pressure ulcers, but the evidence suggests a slight reduction in pressure ulcer area (MD 15.8% lower, 95% CI 25.11 lower to 6.48 lower; 2 studies, 231 participants, low-certainty evidence). The evidence is very uncertain about changes in pressure ulcer scores, acceptability, and side effects of these supplements. Compared to placebo, collagen supplements probably improve the mean change in pressure ulcer area (MD 1.81 cm² smaller, 95% CI 3.36 smaller to 0.26 smaller; 1 study, 74 participants, moderate-certainty evidence). The evidence is very uncertain about the effect of these supplements on side effects. The evidence is very uncertain about the effects of vitamin C, different doses of arginine; EPA, GLA (special dietary fatty acids) and antioxidants; protein; a specialized amino acid mixture; ornithine alpha-ketoglutarate and zinc supplements on pressure ulcer healing (1 or 2 studies each; very low-certainty evidence).

AUTHORS' CONCLUSIONS

The benefits of nutritional interventions with various compositions for pressure ulcer prevention and treatment are uncertain. There may be little or no difference compared to standard nutrition or placebo. Nutritional supplements may not increase gastrointestinal side effects, but the evidence is very uncertain. Larger studies with similar nutrient compositions would reduce these uncertainties. No study investigated the effects of special diets (e.g. protein-enriched diet, vegetarian diet) on pressure ulcer incidence and healing.

The Topical Formulation of Whey Protein for the Prevention of Pressure Ulcers in Critically Ill Patients: A Novel Intervention in a Randomized-Controlled Clinical Trial

Background

High prevalence of pressure ulcers (PUs) and their complications are important dilemmas in the intensive care unit (ICU). Therefore this study was designed to evaluate the effectiveness of topical whey protein formulation in preventing PUs in patients admitted to the ICU.

Materials and Methods

In this randomized placebo-controlled clinical trial under registration number [IRCTdeted for blinded article], 80 eligible ICU patients were randomly allocated to receive topical ointment of whey protein or placebo on the sacrum with a diameter of 15 cm twice daily for seven days, in addition to the routine care. The mean risk score for developing PUs was calculated at baseline using the Braden tool, and the PUSH score was used to assess PUs on days 4, 7, and 14. Patients' related demographic and clinical variables were also collected using a medical record for more evaluation.

Results

Our results showed that demographic characteristics and the Braden scores' baseline mean were not significantly different between groups (P > 0.05). The repeated measures ANOVA test revealed that the mean scores of PUs at various times were markedly lower in the whey protein than in the placebo group (P < 0.001).

Conclusion

This intervention can be routinely added as effective, safe, inexpensive, and accessible care to reduce the incidence of PUs for patients at risk of developing this injury.

Cysteine-Rich Whey Protein Isolate (CR-WPI) Ameliorates Erectile Dysfunction by Diminishing Oxidative Stress via DDAH/ADMA/NOS Pathway

Nitric oxide synthase- (NOS-) dependent endothelial dysfunction induced by oxidative stress (OS) is assumed to play a pivotal role in the pathogenesis and progression of diabetes mellitus-related erectile dysfunction (DMED). Cysteine-rich whey protein isolate (CR-WPI) is a widely used protein supplement and has been confirmed to reduce reactive oxygen species (ROS) by increasing cellular antioxidant glutathione (GSH). However, it is currently unknown whether CR-WPI elicits therapeutic effects in DMED. Here, we provide diabetic rats with CR-WPI to determine its effect on DMED and the underlying mechanisms. The results suggest that CR-WPI supplementation increased GSH biosynthesis and reduced ROS content and simultaneously upregulated the dimethylarginine dimethylaminohydrolase (DDAH)/asymmetrical dimethylarginine (ADMA)/nitric oxide synthase (NOS) metabolic pathway. Evaluation of intracavernous pressure (ICP) also showed an improvement of penile erectile function in CR-WPI-treated rats. The results of the vitro cell culture showed that glutathione pretreatment protected corpus cavernosum smooth muscle cells (CCSMC) from H₂O₂-induced apoptosis by decreasing Caspase 9 and Caspase 3 expressions. These results augur well for the potential therapeutic application of dietary CR-WPI supplementation for treating diabetic erectile dysfunction.

Quantitative determination of D4-cystine in mice using LC-MS/MS and its application to the assessment of pharmacokinetics and bioavailability

Cystine is the primary source material for the synthesis of glutathione. However, the pharmacokinetics and tissue distribution of cystine are largely unknown. A surrogate analyte D₄-cystine was employed to generate calibration curves for the determination of levels of D₄-cystine and endogenous cystine in mice by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Validation assessments proved the sensitivity, specificity and reproducibility of the method with a lower limit of quantification (LLOQ) of 5 ng/mL over 5–5000 ng/mL in plasma. The pharmacokinetics of D₄-cystine were evaluated after administering injections and oral solutions, both of which minimally impacted endogenous cystine levels. The absolute bioavailability of cystine was 18.6%, 15.1% and 25.6% at doses of 25, 50 and 100 mg/kg, respectively. Intravenously injected D₄-cystine resulted in dramatically high plasma levels with reduced levels in the brain and liver. Intragastrically administered D₄-cystine resulted in high levels in the plasma and stomach with relatively low levels in the lung, kidney, heart and brain.

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An LC-MS/MS method was developed to determine exogenous and endogenous cystine with an isotope-labelled surrogate analyte.

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The pharmacokinetics of D₄-cystine were assessed after i.v./i.g. administration and the absolute bioavailability was evaluated.

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For the first time, the distribution of D₄-cystine was profiled in diverse tissues/organs after i.v./i.g. administration.

Endothelium as a Source and Target of H2S to Improve Its Trophism and Function

The vascular endothelium consists of a single layer of squamous endothelial cells (ECs) lining the inner surface of blood vessels. Nowadays, it is no longer considered as a simple barrier between the blood and vessel wall, but a central hub to control blood flow homeostasis and fulfill tissue metabolic demands by furnishing oxygen and nutrients. The endothelium regulates the proper functioning of vessels and microcirculation, in terms of tone control, blood fluidity, and fine tuning of inflammatory and redox reactions within the vessel wall and in surrounding tissues. This multiplicity of effects is due to the ability of ECs to produce, process, and release key modulators. Among these, gasotransmitters such as nitric oxide (NO) and hydrogen sulfide (H₂S) are very active molecules constitutively produced by endotheliocytes for the maintenance and control of vascular physiological functions, while their impairment is responsible for endothelial dysfunction and cardiovascular disorders such as hypertension, atherosclerosis, and impaired wound healing and vascularization due to diabetes, infections, and ischemia. Upregulation of H₂S producing enzymes and administration of H₂S donors can be considered as innovative therapeutic approaches to improve EC biology and function, to revert endothelial dysfunction or to prevent cardiovascular disease progression. This review will focus on the beneficial autocrine/paracrine properties of H₂S on ECs and the state of the art on H₂S potentiating drugs and tools.

Potential role of hydrogen sulfide in diabetes-impaired angiogenesis and ischemic tissue repair

Diabetes is one of the most prevalent metabolic disorders and is estimated to affect 400 million of 4.4% of population worldwide in the next 20 year. In diabetes, risk to develop vascular diseases is two-to four-fold increased. Ischemic tissue injury, such as refractory wounds and critical ischemic limb (CLI) are major ischemic vascular complications in diabetic patients where oxygen supplement is insufficient due to impaired angiogenesis/neovascularization. In spite of intensive studies, the underlying mechanisms of diabetes-impaired ischemic tissue injury remain incompletely understood. Hydrogen sulfide (H₂S) has been considered as a third gasotransmitter regulating angiogenesis under physiological and ischemic conditions. Here, the underlying mechanisms of insufficient H₂S-impaired angiogenesis and ischemic tissue repair in diabetes are discussed. We will primarily focuses on the signaling pathways of H₂S in controlling endothelial function/biology, angiogenesis and ischemic tissue repair in diabetic animal models. We summarized that H₂S plays an important role in maintaining endothelial function/biology and angiogenic property in diabetes. We demonstrated that exogenous H₂S may be a theraputic agent for endothelial dysfunction and impaired ischemic tissue repair in diabetes.