Time-restricted feeding prevents ionizing radiation-induced hematopoietic stem cell damage by inhibiting NOX-4/ROS/p38 MAPK pathway

Ionizing radiation (IR)-induced damage to the hematopoietic system is a prominent symptom following exposure to total body irradiation (TBI). The exploration of strategies aimed at to mitigating radiation-induced hematopoietic damage assumes paramount importance. Time-restricted feeding (TRF) has garnered attention for its beneficial effects in various diseases. In this study, we evaluated the preventive effects of TRF on TBI-induced hematopoietic damage. The results suggested that TRF significantly enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects might be attributed to the inhibition of the NOX-4/ROS/p38 MAPK pathway in hematopoietic stem cells. TRF also influenced the expression of nuclear factor erythroid2-related factor 2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, TRF alleviated aberrations in plasma metabolism by inhibiting the mammalian target of rapamycin. These findings suggest that TRF may represent a novel approach to preventing hematopoietic radiation damage.

Empagliflozin attenuates radiation-induced hematopoietic damage via NOX-4/ROS/p38 pathway

PURPOSE

Damage to the hematopoietic system and functional inhibition are severe consequences of radiation exposure. In this study, we have investigated the effect of empagliflozin on radiation-induced hematopoietic damage, with the aim of providing new preventive approach to such injuries.

METHODS AND MATERIALS

Mice were given 4 Gy total body irradiation (TBI) 1 h after the oral administration of empagliflozin, followed by the continuous administration of the same dose of empagliflozin for 6d, and then sacrificed on the 10th day after irradiation. The reactive oxygen species (ROS) levels in hematopoietic cells and their regulatory mechanisms were also been investigated. Colony forming unit granulocyte macrophage assay and bone marrow transplantation assays were performed to detect the function of the bone marrow cells.

KEY FINDINGS

Empagliflozin increased the cell viability, reduced ROS levels, and attenuated apoptosis in vitro after the bone marrow cells were exposed to 1 Gy radiation. Empagliflozin significantly attenuated ionizing radiation injuries to the hematopoietic system, increased the peripheral blood cell count, and enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects may be related to the NOX-4/ROS/p38 pathway-mediated suppression of MAPK in hematopoietic stem cells. Empagliflozin also influenced the expression of Nrf-2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, empagliflozin mitigated metabolic abnormalities by inhibiting the mammalian target of rapamycin.

SIGNIFICANCE

Our study has demonstrated that empagliflozin can reduce radiation-induced injury in hematopoietic stem cells. This finding suggests that empagliflozin is a promising novel agent for preventing radiation-induced damage to the hematopoietic system.

Effects of Angiotensin Receptor Blockers on Streptozotocin-Induced Diabetic Cataracts

This study aimed to determine the role of oxidative stress produced by the renin-angiotensin system (RAS) in cataract formation in streptozotocin-induced diabetic rats (STZ) using angiotensin II receptor blockers (ARBs). Rats were treated with streptozotocin and orally administered candesartan (2.5 mg/kg/day) or a normal diet for 10 weeks until sacrifice. Cataract progression was assessed through a slit-lamp examination. Animals were euthanized at 18 weeks, and the degree of cataract progression was evaluated. Oxidative stress was also assessed. In STZ-treated rats, lens opacity occurred at 12 weeks. Cataract progression was inhibited in the ARB-treated group compared with the placebo group (p < 0.05). STZ-treated rats exhibited upregulated angiotensin-converting enzyme (ACE) gene expression than control rats. Oxidative stress-related factors were upregulated in the placebo-treated group but suppressed in the ARB-treated group. A correlation coefficient test revealed a positive correlation between ACE gene expression and oxidative stress-related factors and a negative correlation between ACE and superoxide dismutase. Immunostaining revealed oxidative stress-related factors and advanced glycation end products in the lens cortex of the placebo-treated group. The mechanism of diabetic cataracts may be related to RAS, and the increase in focal ACE and angiotensin II in the lens promotes oxidative stress-related factor production.

Krüppel-like Factor 9 (KLF9) Suppresses Hepatocellular Carcinoma (HCC)-Promoting Oxidative Stress and Inflammation in Mice Fed High-Fat Diet

Obesity, oxidative stress, and inflammation are risk factors for hepatocellular carcinoma (HCC). We examined, in mice, the effects of Krüppel-like factor 9 (KLF9) knockout on: adiposity, hepatic and systemic oxidative stress, and hepatic expression of pro-inflammatory and NOX/DUOX family genes, in a high-fat diet (HFD) context. Male and female Klf9^+/+ (wild type, WT) and Klf9^-/- (knockout, KO) mice were fed HFD (beginning at age 35 days) for 12 weeks, after which liver and adipose tissues were obtained, and serum adiponectin and leptin levels, liver fat content, and markers of oxidative stress evaluated. Klf9^-/- mice of either sex did not exhibit significant alterations in weight gain, adipocyte size, adipokine levels, or liver fat content when compared to WT counterparts. However, Klf9^-/- mice of both sexes had increased liver weight/size (hepatomegaly). This was accompanied by increased hepatic oxidative stress as indicated by decreased GSH/GSSG ratio and increased homocysteine, 3-nitrotyrosine, 3-chlorotyrosine, and 4HNE content. Decreased GSH to GSSG ratio and a trend toward increased homocysteine levels were observed in the corresponding Klf9^-/- mouse serum. Gene expression analysis showed a heightened pro-inflammatory state in livers from Klf9^-/- mice. KLF9 suppresses hepatic oxidative stress and inflammation, thus identifying potential mechanisms for KLF9 suppression of HCC and perhaps cancers of other tissues.

The protective effects of S14G-humanin (HNG) against mono-sodium urate (MSU) crystals- induced gouty arthritis

Gout is a common and complex form of arthritis that has brought great inconveniences to the normal lives of patients. It is reported that oxidative stress and nod-like receptor family protein 3 (NLRP3) inflammasome-mediated inflammatory reactions are involved in the pathogenesis of gout arthritis. S14G-humanin (S14G-HNG) is a modified peptide of HNG with higher inhibitory activity on the accumulation and deposition of Aβ. Recently, S14G-HNG has been reported to exert great anti-inflammatory effects. The present study proposed to explore the possible therapeutic property of S14G-HNG against gout arthritis. An animal model was established by stimulation with mono-sodium urate (MSU) crystals, followed by treatment with colchicine and S14G-HNG, respectively. The elevated Gait score promoted synovitis score and activated myeloperoxidase (MPO) observed in MSU crystals-treated mice were significantly reversed by colchicine and S14G-HNG. Bone marrow-derived macrophages (BMDMs) were isolated from mice and stimulated with MSU crystals, followed by being treated with 25 and 50 μM S14G-HNG. The increased mitochondrial reactive oxygen species (ROS) and Malondialdehyde (MDA) levels, upregulated NADPH oxidase-4 (NOX-4), activated NLRP3 inflammasome, and elevated production of inflammatory factors in MSU crystals-treated BMDMs were dramatically reversed by S14G-HNG, accompanied by the upregulation of sirtuin type-1 (SIRT1). Lastly, the protective effects of S14G-HNG against MSU crystals-induced NLRP3 inflammasome activation were significantly abolished by the knockdown of SIRT1. In conclusion, our data reveal that S14G-HNG could possess potential benefits against MSU crystals-induced gout arthritis, with colchicine displaying a better effect.

Modulation of COX-2 and NADPH oxidase-4 by alpha-lipoic acid ameliorates busulfan-induced pulmonary injury in rats

Aims

This study aimed to explore the potential protective effect of α-lipoic acid on busulfan-induced pulmonary fibrosis in rats.

Main methods

Eighteen adult male rats were divided into 3 groups; control, busulfan, and busulfan plus α-lipoic acid groups. Lung index ratio, serum level of proinflammatory cytokine were assessed. The activities of antioxidant enzymes and lipid peroxidation products were estimated in the lung tissues in addition to the histopathological analyses. The deposition of the collagen in the lung tissues was evaluated by Sirius red staining. The expressions of α-smooth muscle actin (α-SMA), TNF-α, and Caspase 3 were determined immunohistochemically. The pulmonary expression of COX-2 and NOX-4 mRNA was assessed using qRT-PCR.

Key findings

Administration of ALA significantly protect the lung against BUS-induced pulmonary fibrosis, besides the upregulation of antioxidants, and downregulation of pro-inflammatory cytokines. Also, it reduced collagen deposition that associated with a decreased expression of α-SMA, TNF-α, and Caspase 3 in the lung tissues. Moreover, ALA significantly upregulated the expression of COX-2 concomitant with the downregulation of elevated NOX-4.

Significance

ALA attenuates the lung cytotoxicity of busulfan through its anti-inflammatory, anti-apoptotic, and antifibrotic effects that may be mediated by upregulation of COX-2 and downregulation of NOX-4.

Modulation of NADPH oxidase and Nrf2/HO-1 pathway by vanillin in cisplatin-induced nephrotoxicity in rats

OBJECTIVES

To investigate the protective effect of vanillin in cisplatin (CP)-induced nephrotoxicity in rats and elucidate the role of nrf-2 and its downstream antioxidant molecules.

METHODS

Rats received vanillin (100 mg/kg orally) for 10 constitutive days and CP (7.5 mg/kg, once, ip) on day 6 of vanillin administration.

KEY FINDINGS

Cisplatin suppressed body weight gain, increased serum urea and creatinine and renal malondialdehyde and nitric oxide while decreased renal total antioxidant capacity. Up-regulation of NADPH oxidase-4 (NOX-4) was marked in renal tissue of CP-treated rats along with down-regulation of the antioxidant genes (nuclear factor erythroid 2-related factor2 (NRF2) and haem oxygenase-1(HO-1)). Increased tumour necrosis factor-α and decreased interleukin-10 with increased myeloperoxidase activity were apparent in renal tissue of CP-treated rats along with marked tubular injury, neutrophil infiltration and increased apoptosis (caspase-3) and some degree of interstitial fibrosis. Vanillin prophylactic administration prevented the deterioration of kidney function, oxidative and nitrosative stress. It also suppressed NOX-4 and up-regulated NRF2 and HO-1 expression in renal tissue. Inflammation, apoptosis and tubular injury were also inhibited by vanillin.

CONCLUSIONS

The antioxidant mechanism by which vanillin protected against CP-induced nephrotoxicity involved the inhibition of NOX-4 along with the stimulation of Nrf2/HO-1 signalling pathway. These in turn inhibited inflammation and apoptosis.

MicroRNAs 342 and 450 together with NOX-4 activity and their association with coronary artery disease in diabetes

BACKGROUND

Dysregulation of miRNAs has been associated with many clinical conditions, including coronary artery disease (CAD). MiRNAs roles in patients with type 2 diabetes mellitus (T2D) with or without CAD, however, have not been clearly understood. Therefore we studied the expression of miRNAs 342 and 450 and the activity of the NADPH oxidase 4 (NOX-4), and their association with anthropometric and biochemical parameters of hyperglycaemia and dyslipidaemia.

SUBJECTS AND METHODS

Blood was collected from 200 outpatient subjects, divided into four groups of 50 individuals including control, T2D, CAD, and T2D with CAD. CAD was further divided based on CAD with angina, CAD clots, and CAD ischaemia to differentiate the primary cause of CAD. We measured the miRNAs 342 and 450 expression and NOX-4 activity, in addition to routine parameters.

RESULTS

The expression of miRNAs 342 and 450 and NOX-4 activity was significantly different between groups. Furthermore, they presented significant correlations with routine parameters, providing evidence of a potentially beneficial role in stratifying the risk for CAD in patients with T2D.

CONCLUSION

The results of this study suggest that the expression of miRNAs 342 and 450 and NOX-4 activity may help identify those individuals with T2D at high risk for developing CAD as well as the prognosis in those with established CAD.

Fenofibrate improves renal function by amelioration of NOX-4, IL-18, and p53 expression in an experimental model of diabetic nephropathy

Among several pathological mechanisms involved in diabetic nephropathy, oxidative stress, inflammation, and apoptosis play a prominent role. Fenofibrate, a peroxisome proliferator-activated receptor-α (PPAR-α) agonist, has markedly improved oxidative stress and inflammatory responses, but there is no evidence about its effects on interleukin-18 (IL-18), NADPH oxidase type 4 (NOX-4), and p53 expression in diabetic kidneys. The aim of this study was to evaluate possible effects of fenofibrate on improving the underlying mechanisms of diabetic nephropathy. Male Wistar rats were randomly divided into four groups namely, normal, normal treated, diabetic and diabetic treated (N = 6). Diabetes was induced by a single dose of streptozotocin (40 mg/kg; IV). Treated animals received fenofibrate for 8 weeks daily (80 mg/kg; po). All groups were sacrificed on day 56 and blood, urine, and tissue samples were collected. Serum levels of urea, uric acid, creatinine, and glucose were assessed. Then, serum levels of malondialdehyde (MDA), nitrate, and glutathione (GLT), as well as the activities of catalase (CAT) and superoxide dismutase (SOD) enzymes were measured. The expression level of NOX-4, IL-18, and p53 proteins at both mRNA and protein levels were evaluated. Diabetes significantly increased albuminuria, free radicals production, inflammation, and apoptosis in non-treated rats while lowered antioxidant capacity. Moreover, diabetes caused histological damages leading to renal failure. Treatment with fenofibrate improved renal function by improving creatinine clearance (P = 0.01) and protein excretion (P = 0.001) and lowering plasma levels of blood urea nitrogen (P = 0.001), creatinine (P = 0.001), and uric acid (P = 0.01). Fenofibrate potentiated antioxidant defense systems by enhancing CAT (P = 0.01) and SOD (P = 0.01) enzymes activities and GLT content (P = 0.01), and reduced oxidative damage by lowering MDA generation (P = 0.02). Fenofibrate also attenuated the expression of NOX-4 (P = 0.05), IL-18 (P = 0.05), and p53 (P = 0.05) at both mRNA and protein levels. In conclusion, treatment with fenofibrate improved renal function by suppression of oxidative stress, attenuation of inflammation, and inhibition of apoptosis.

NADPH oxidases and vascular remodeling in cardiovascular diseases

Reactive oxygen species (ROS) are key signaling molecules that regulate vascular function and structure in physiological conditions. A misbalance between the production and detoxification of ROS increases oxidative stress that is involved in the vascular remodeling associated with cardiovascular diseases such as hypertension by affecting inflammation, hypertrophy, migration, growth/apoptosis and extracellular matrix protein turnover. The major and more specific source of ROS in the cardiovascular system is the NADPH oxidase (NOX) family of enzymes composed of seven members (NOX1-5, DUOX 1/2). Vascular cells express several NOXs being NOX-1 and NOX-4 the most abundant NOXs present in vascular smooth muscle cells. This review focuses on specific aspects of NOX-1 and NOX-4 isoforms including information on regulation, function and their role in vascular remodeling. In order to obtain a more integrated view about the role of the different NOX isoforms in different types of vascular remodeling, we discuss the available literature not only on hypertension but also in atherosclerosis, restenosis and aortic dilation.

Complement-dependent NADPH oxidase enzyme activation in renal ischemia/reperfusion injury

NADPH oxidase plays a central role in mediating oxidative stress during heart, liver, and lung ischemia/reperfusion injury, but limited information is available about NADPH oxidase in renal ischemia/reperfusion injury. Our aim was to investigate the activation of NADPH oxidase in a swine model of renal ischemia/reperfusion damage. We induced renal ischemia/reperfusion in 10 pigs, treating 5 of them with human recombinant C1 inhibitor, and we collected kidney biopsies before ischemia and 15, 30, and 60 min after reperfusion. Ischemia/reperfusion induced a significant increase in NADPH oxidase 4 (NOX-4) expression at the tubular level, an upregulation of NOX-2 expression in infiltrating monocytes and myeloid dendritic cells, and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis along with a marked upregulation of NADPH-dependent superoxide generation. This burden of oxidative stress was associated with an increase in tubular and interstitial expression of the myofibroblast marker α-smooth muscle actin (α-SMA). Interestingly, NOX-4 and NOX-2 expression and the overall NADPH oxidase activity as well as α-SMA expression and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis were strongly reduced in C1-inhibitor-treated animals. In vitro, when we incubated tubular cells with the anaphylotoxin C3a, we observed an enhanced NADPH oxidase activity and α-SMA protein expression, which were both abolished by NOX-4 silencing. In conclusion, our findings suggest that NADPH oxidase is activated during ischemia/reperfusion in a complement-dependent manner and may play a potential role in the pathogenesis of progressive renal damage in this setting.