Complexity of NAC Action as an Antidiabetic Agent: Opposing Effects of Oxidative and Reductive Stress on Insulin Secretion and Insulin Signaling.

Dysregulated redox balance is involved in the pathogenesis of type 2 diabetes. While the benefit of antioxidants in neutralizing oxidative stress is well characterized, the potential harm of antioxidant-induced reductive stress is unclear. The aim of this study was to investigate the dose-dependent effects of the antioxidant N-acetylcysteine (NAC) on various tissues involved in the regulation of blood glucose and the mechanisms underlying its functions. H2O2 was used as an oxidizing agent in order to compare the outcomes of oxidative and reductive stress on cellular function. Cellular death in pancreatic islets and diminished insulin secretion were facilitated by H2O2-induced oxidative stress but not by NAC. On the other hand, myotubes and adipocytes were negatively affected by NAC-induced reductive stress, as demonstrated by the impaired transmission of insulin signaling and glucose transport, as opposed to H2O2-stimulatory action. This was accompanied by redox balance alteration and thiol modifications of proteins. The NAC-induced deterioration of insulin signaling was also observed in healthy mice, while both insulin secretion and insulin signaling were improved in diabetic mice. This study establishes the tissue-specific effects of NAC and the importance of the delicate maintenance of redox balance, emphasizing the challenge of implementing antioxidant therapy in the clinic.

Maternal N-Acetyl Cysteine Intake Improved Glucose Tolerance in Obese Mice Offspring.

Exposure to certain environmental factors during the early stages of development was found to affect health in adulthood. Among other environmental factors, oxidative stress has been suggested to be involved in fetal programming, leading to elevated risk for metabolic disorders, including type 2 diabetes; however, the possibility that antioxidant consumption during early life may affect the development of diabetes has scarcely been studied. The aim of this study was to investigate the effects of N-acetyl-l-cysteine (NAC) given during pregnancy and lactation on the susceptibility of offspring to develop glucose intolerance at adulthood. C57bl6/J mice were given NAC during pregnancy and lactation. High fat diet (HFD) was given to offspring at an age of 6 weeks for an additional 9 weeks, till the end of the study. Isolated islets of NAC-treated offspring (6 weeks old, before HFD feeding) had an increased efficacy of glucose-stimulated insulin secretion and a higher resistance to oxidative damage. Following HFD feeding, glucose tolerance and insulin sensitivity of NAC-treated offspring were improved. In addition, islet diameter was lower in male offspring of NAC-treated mice compared to their HFD-fed littermates. NAC consumption during early life improves glucose tolerance in adulthood in mice.

Metabolic alterations and cellular responses to ß-Hydroxybutyrate treatment in breast cancer cells.

BACKGROUND: The ketogenic diet (KD), based on high fat (over 70% of daily calories), low carbohydrate, and adequate protein intake, has become popular due to its potential therapeutic benefits for several diseases including cancer. Under KD and starvation conditions, the lack of carbohydrates promotes the production of ketone bodies (KB) from fats by the liver as an alternative source of metabolic energy. KD and starvation may affect the metabolism in cancer cells, as well as tumor characteristics. The aim of this study is to evaluate the effect of KD conditions on a wide variety of aspects of breast cancer cells in vitro. METHODS: Using two cancer and one non-cancer breast cell line, we evaluate the effect of ß-hydroxybutyrate (ßHb) treatment on cell growth, survival, proliferation, colony formation, and migration. We also assess the effect of KB on metabolic profile of the cells. Using RNAseq analysis, we elucidate the effect of ßHb on the gene expression profile. RESULTS: Significant effects were observed following treatment by ßHb which include effects on viability, proliferation, and colony formation of MCF7 cells, and different effects on colony formation of MDA-MB-231 cells, with no such effects on non-cancer HB2 cells. We found no changes in glucose intake or lactate output following ßHb treatment as measured by LC-MS, but an increase in reactive oxygen species (ROS) level was detected. RNAseq analysis demonstrated significant changes in genes involved in lipid metabolism, cancer, and oxidative phosphorylation. CONCLUSIONS: Based on our results, we conclude that differential response of cancer cell lines to ßHb treatment, as alternative energy source or signal to alter lipid metabolism and oncogenicity, supports the need for a personalized approach to breast cancer patient treatment.

Redox Balance in Type 2 Diabetes: Therapeutic Potential and the Challenge of Antioxidant-Based Therapy.

Oxidative stress is an important factor in the development of type 2 diabetes (T2D) and associated complications. Unfortunately, most clinical studies have failed to provide sufficient evidence regarding the benefits of antioxidants (AOXs) in treating this disease. Based on the known complexity of reactive oxygen species (ROS) functions in both the physiology and pathophysiology of glucose homeostasis, it is suggested that inappropriate dosing leads to the failure of AOXs in T2D treatment. To support this hypothesis, the role of oxidative stress in the pathophysiology of T2D is described, together with a summary of the evidence for the failure of AOXs in the management of diabetes. A comparison of preclinical and clinical studies indicates that suboptimal dosing of AOXs might explain the lack of benefits of AOXs. Conversely, the possibility that glycemic control might be adversely affected by excess AOXs is also considered, based on the role of ROS in insulin signaling. We suggest that AOX therapy should be given in a personalized manner according to the need, which is the presence and severity of oxidative stress. With the development of gold-standard biomarkers for oxidative stress, optimization of AOX therapy may be achieved to maximize the therapeutic potential of these agents.

Optimizing the average distance between a blue light photosensitizer and a harmonic nanoparticle for effective infrared photodynamic therapy.

Photodynamic therapy can be significantly improved by techniques utilizing light windows of higher tissue penetration depths with optimally matched photoactive agents to provide deep interstitial treatment. Classical blue light photosensitizers were photodynamically activated using infrared light via coupled harmonic nanoparticles with optimized intermediary distances using spacers. Upon 800 nm pulsed laser irradiation perovskite nanoparticles with optimized coupling to either curcumin or protoporphyrin IX reduced the viability of MCF7 breast cancer cells by 73 percent and 64 percent, respectively, while exhibiting negligible dark toxicity. The findings pave the way for clinical adaptation of ease-of-synthesis photodynamically active preparations operable under deep tissue penetrating infrared lights using commonly available otherwise infrared inactive classical blue light photosensitizers.

Anti-inflammatory effects of Sarcopoterium spinosum extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Sarcopoterium spinosum is a Mediterranean plant, widely used by the Beduin traditional medicine. While its major use is for the treatment of diabetes, there are also documentations for its use as anti-inflammatory agent. This therapeutic potential of Sarcopoterium spinosum was not validated before. AIM OF THE STUDY: To investigate the anti-inflammatory properties of Sarcopoterium spinosum extract (SSE). MATERIALS AND METHODS: Experiments were performed on RAW264.7 macrophages and bone marrow-derived macrophages (BMDM) and the effect of SSE on markers of inflammation was investigated. In addition, the effect of SSE on the development of inflammation in adipose-tissue of obese, insulin resistant mice was measured in KK-Ay mice and high fat diet (HFD)-fed mice. RESULTS: Lipopolysaccharide (LPS) and SSE increased the viability of RAW264.7. In addition, the cells acquired distinct dendritic-like morphology, however, while LPS induced NO production and the mRNA expression of pro-inflammatory cytokines, SSE increased the mRNA expression of anti-inflammatory genes and blocked LPS effects. All three pathways of MAPK were activated by LPS and SSE, as demonstrated by the phosphorylation of ERK, p38 and JNK. NFκB was activated and Akt was phosphorylated by LPS, while SSE blocked this effects. STAT proteins were differently phosphorylated by SSE and LPS. Immunomodulatory effects of SSE were also found in BMDM. In adipose tissue of SSE-treated mice, less crown-like structures were found, and lower expression of pro-inflammatory adipocytokines was observed, although adipocytes hypertrophy was not affected. CONCLUSIONS: SSE has an immunomodulatory effects that affect macrophage function, and reduces adipose tissue inflammation. Identifying active component and clarifying its mechanism of action might support the development of new anti-inflammatory agent.

N-Acetyl-l-Cysteine Supplement in Early Life or Adulthood Reduces Progression of Diabetes in Nonobese Diabetic Mice.

BACKGROUND: Oxidative stress contributes to the pathologic process leading to the development, progression, and complications of type 1 diabetes (T1D). OBJECTIVE: The aim of this study was to investigate the effect of the antioxidant N-acetyl-l-cysteine (NAC), supplemented during early life or adulthood on the development of T1D. METHODS: NAC was administered to nonobese diabetic (NOD) female mice during pregnancy and lactation, and the development of diabetes was followed in offspring. In an additional set of experiments, offspring of untreated mice were given NAC during adulthood, and the development of T1D was followed. Morbidity rate, insulitis and serum cytokines were measured in the 2 sets of experiments. In addition, markers of oxidative stress, glutathione, lipid peroxidation, total antioxidant capacity and activity of antioxidant enzymes, were followed. RESULTS: Morbidity rate was reduced in both treatment protocols. A decrease in interferon γ, tumor necrosis factor α, interleukin 1α, and other type 1 diabetes-associated proinflammatory cytokines was found in mice supplemented with NAC in adulthood or during early life compared with control NOD mice. The severity of insulitis was higher in control NOD mice than in treated groups. NAC administration significantly reduced oxidative stress, as determined by reduced lipid peroxidation and increased total antioxidant capacity in serum and pancreas of mice treated in early life or in adulthood and increased pancreatic glutathione when administrated in adulthood. The activity of antioxidant enzymes was not affected in mice given NAC in adulthood, whereas an increase in the activity of superoxide dismutase and catalase was demonstrated in the pancreas of their offspring. CONCLUSION: NAC decreased morbidity of NOD mice by attenuating the immune response, presumably by eliminating oxidative stress, and might be beneficial in reducing morbidity rates of T1D in high-risk individuals.