Antioxidant Roles of SGLT2 Inhibitors in the Kidney

The reduction-oxidation (redox) system consists of the coupling and coordination of various electron gradients that are generated thanks to serial reduction-oxidation enzymatic reactions. These reactions happen in every cell and produce radical oxidants that can be mainly classified into reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS modulate cell-signaling pathways and cellular processes fundamental to normal cell function. However, overproduction of oxidative species can lead to oxidative stress (OS) that is pathological. Oxidative stress is a main contributor to diabetic kidney disease (DKD) onset. In the kidney, the proximal tubular cells require a high energy supply to reabsorb proteins, metabolites, ions, and water. In a diabetic milieu, glucose-induced toxicity promotes oxidative stress and mitochondrial dysfunction, impairing tubular function. Increased glucose level in urine and ROS enhance the activity of sodium/glucose co-transporter type 2 (SGLT2), which in turn exacerbates OS. SGLT2 inhibitors have demonstrated clear cardiovascular benefits in DKD which may be in part ascribed to the generation of a beneficial equilibrium between oxidant and antioxidant mechanisms.

Restricting tumor lactic acid metabolism using dichloroacetate improves T cell functions

Background Lactic acid produced by tumors has been shown to overcome immune surveillance, by suppressing the activation and function of T cells in the tumor microenvironment. The strategies employed to impair tumor cell glycolysis could improve immunosurveillance and tumor growth regulation. Dichloroacetate (DCA) limits the tumor-derived lactic acid by altering the cancer cell metabolism. In this study, the effects of lactic acid on the activation and function of T cells, were analyzed by assessing T cell proliferation, cytokine production and the cellular redox state of T cells. We examined the redox system in T cells by analyzing the intracellular level of reactive oxygen species (ROS), superoxide and glutathione and gene expression of some proteins that have a role in the redox system. Then we co-cultured DCA-treated tumor cells with T cells to examine the effect of reduced tumor-derived lactic acid on proliferative response, cytokine secretion and viability of T cells. Result We found that lactic acid could dampen T cell function through suppression of T cell proliferation and cytokine production as well as restrain the redox system of T cells by decreasing the production of oxidant and antioxidant molecules. DCA decreased the concentration of tumor lactic acid by manipulating glucose metabolism in tumor cells. This led to increases in T cell proliferation and cytokine production and also rescued the T cells from apoptosis. Conclusion Taken together, our results suggest accumulation of lactic acid in the tumor microenvironment restricts T cell responses and could prevent the success of T cell therapy. DCA supports anti-tumor responses of T cells by metabolic reprogramming of tumor cells.

Role of Plasma Membrane Redox Activities in Immune Response Mechanisms

The plasma membrane redox system (PMRS) is an important component of the cell's ability to defend itself against oxidative stress. Many immune signaling pathways are regulated through redox reactions. Biological systems utilize oxidationreduction reactions to modulate their responses to environmental cues. The role of redox molecules such as NO and ROS as key mediators of immunity has recently gathered a lot of interest and attention. Beyond the chemical interactions of NO and ROS that combine to eradicate pathogens, these redox small molecules are effective immune-modulators that regulate cellular metabolism as well as multiple pro-inflammatory and repair/tissue-restoration pathways. Redox molecules such as peroxide, superoxide, NO, and RNS, once thought to be only toxic, are essential in tissue repair. These species are generated, converted and metabolized during host microbe interaction involving the innate immune system. Cytochrome b558 is the flavin binding component of the NADPH oxidase. NADPH oxidases are key producers of ROS. A variety of RNS and ROS is produced in the acidic mileu of phagosomes, which provide an environment conducive to the redox chemistry, which is the first line in fighting infection. Bacterial cell immune response also involves NO. Thus understanding the plasma membrane redox activities can help unravel the mechanisms of immune response. Keywords: Plasma membrane, Redox activities, oxidative stress, NO, ROS, RNS. Nitrous Oxide, Reactive Oxygen Species, Reactive Nitrogen species.

The Effect of Acute Oral Galactose Administration on the Redox System of the Rat Small Intestine

Galactose is a ubiquitous monosaccharide with important yet incompletely understood nutritive and physiological roles. Chronic parenteral d-galactose administration is used for modeling aging-related pathophysiological processes in rodents due to its ability to induce oxidative stress (OS). Conversely, chronic oral d-galactose administration prevents and alleviates cognitive decline in a rat model of sporadic Alzheimer’s disease, indicating that galactose may exert beneficial health effects by acting in the gut. The present aim was to explore the acute time-response of intestinal redox homeostasis following oral administration of d-galactose. Male Wistar rats were euthanized at baseline (n = 6), 30 (n = 6), 60 (n = 6), and 120 (n = 6) minutes following orogastric administration of d-galactose (200 mg/kg). The overall reductive capacity, lipid peroxidation, the concentration of low-molecular-weight thiols (LMWT) and protein sulfhydryls (SH), the activity of Mn and Cu/Zn superoxide dismutases (SOD), reduced and oxidized fractions of nicotinamide adenine dinucleotide phosphates (NADPH/NADP), and the hydrogen peroxide dissociation rate were analyzed in duodenum and ileum. Acute oral administration of d-galactose increased the activity of SODs and decreased intestinal lipid peroxidation and nucleophilic substrates (LMWT, SH, NADPH), indicating activation of peroxidative damage defense pathways. The redox system of the small intestine can acutely tolerate even high luminal concentrations of galactose (0.55 M), and oral galactose treatment is associated with a reduction rather than the increment of the intestinal OS. The ability of oral d-galactose to modulate intestinal OS should be further explored in the context of intestinal barrier maintenance, and beneficial cognitive effects associated with long-term administration of low doses of d-galactose.

Lactose and Casein Cause Changes on Biomarkers of Oxidative Damage and Dysbiosis in an Experimental Model of Multiple Sclerosis

Background and Objectives: Experimental autoimmune encephalomyelitis (EAE) in rats closely reproduces multiple sclerosis (MS), a disease characterized by neuroinflammation and oxidative stress, that also appears to extend to other organ compartments. The origin of MS is a matter for discussion, but it would seem that altering certain bacterial populations present in the gut may lead to a proinflammatory condition due to the bacterial lipopolysaccharides (LPS) in the so-called brain-gut axis. The casein and lactose in milk confer anti-inflammatory properties and immunomodulatory effects. The objectives of this study were: to evaluate the effects of administration of casein and lactose on the oxidative damage and the clinical status caused by EAE, and to verify whether both, casein and lactose, had any effect on the LPS and its transport protein -LBP-. Methods: Twenty male dark Agouti rats were divided into: control rats (control), EAE rats and EAE rats to which casein and lactose, EAE+casein and EAE+lactose, respectively, were administered. Fifty-one days after casein and lactose administration, the rats were sacrificed and different organs were studied (brain, spinal cord, blood, heart, liver, kidney, small and large intestine). In the latter, products derived from oxidative stress were studied (lipid peroxides and carbonylated proteins) as well as the glutathione redox system, various inflammation factors (total nitrite, Nuclear Factor-kappa B p065, the Rat Tumour Necrosis Factor-α) and the LPS and LBP values. Results and Conclusion: Casein and lactose administration improved the clinical aspect of the disease at the same time as reducing inflammation and oxidative stress, exerting its action on the glutathione redox system or increasing GPx levels.

Zingerone Attenuates Methotrexate-Induced Hepatotoxicity in Rats

Background: Methotrexate (MTX) is mainly used for the chemotherapy of different types of malignancy and some autoimmune diseases like rheumatoid arthritis and inflammatory bowel disease. The MTX application is limited by its severe side effects, including several types of hepatic injury. Objectives: In this study, we decided to evaluate if zingerone (the main constituent of ginger) can reduce the hepatic side effects of MTX. Methods: Thirty-five rats were divided into five groups: Control group receiving normal saline (N/S), once daily, by gavage, for 10 days, and N/S intraperitoneally (i.p.), a single dose on the ninth day; Methotrexate (MTX) group receiving N/S, once daily, by gavage, for 10 days, and MTX (i.p.), a single dose (20 mg/kg) on the ninth day; Groups 3 (ZG25), 4 (ZG50), and 5 (ZG100) receiving zingerone (25, 50, and 100 mg/kg, respectively), once daily, by gavage, for 10 days, and MTX (i.p.), a single dose (20 mg/kg) on the ninth day. Results: The results showed a significant decrease in serum AST, ALT, and ALP, as well as the hepatic content of MDA, NO, PC, TNF-α, and IL-1β, in the ZG groups compared with the MTX group. The activity of SOD, CAT, and GPX, as well as the hepatic content of GSH, showed a significant increase in the ZG groups compared with the MTX group. Histopathological improvement in the hepatic tissue of ZG groups compared with the MTX group confirmed all other findings. Conclusions: It is concluded that zingerone can improve hepatic injury induced by MTX in rats regarding the redox system features, inflammation, and histological changes. This can make humans hopeful for using Ginger in the future for attenuating the hepatic side effects of MTX when used chronically.

User-friendly, magnetically sealed plug-and-play sensor module for online electrochemical sensing for fluidic devices

The growth in fluidic devices, such as organ-on-chip (OOC) technology, comes with a need for growth in sensing capabilities of key biomolecules to help elucidate changes during the time course of experiments. We developed an on-line, easy-to-assemble, 3D-printed electrochemical sensor module that is magnetically sealed for ease of assembly. The sensor module includes a plug-and-play format for electrochemical sensors made in finger-tight fittings to allow for a wide selection of experimental set-ups and target molecules. Here, we report the feasibility of the sensor module as well as demonstrate its use for electrochemical sensing with integrated thermoplastic electrodes (TPEs). The sensor module withstood over 300 kPa of backpressure and demonstrated reliable performance with TPEs when using cyclic voltammetry (CV) and amperometry under flow conditions. CVs using the ferri/ferrocyanide (K3/4[Fe(CN)6]) redox system demonstrate that the sensor module does not hinder the expected linear response with respect to analyte concentration. Further CVs and amperometry demonstrated the use of the sensor module under flow conditions. Such success in device design and usability is promising for future work using the on-line sensor module with a variety of applications.