Oral high dose vitamin B12 decreases renal superoxide and post-ischemia/reperfusion injury in mice

Knockdown of Leucine-rich alpha-2-glycoprotein 1 alleviates renal ischemia-reperfusion injury by inhibiting NOX4-mediated apoptosis, inflammation, and oxidative stress

Renal ischemia-reperfusion (I/R) injury leads mainly to acute kidney injury. Leucine-rich alpha-2-glycoprotein 1 (LRG) is upregulated in kidney tissues of mice after renal I/R injury. However, its role in renal I/R injury has not been fully elucidated. A mouse model of renal I/R injury was constructed by unilateral renal pedicle clamping and reperfusion. Mice undergoing I/R procedures exhibited renal function impairment and increased LRG protein expression compared with mice receiving sham operations. Tail vein injection with lentivirus carrying shLRG decreased renal I/R injury-induced increase in caspase-3 activity, IL-1β and IL-18 concentrations, and ROS production. Furthermore, shRNA-mediated LRG knockdown in HK-2 cells protected against H/R-induced cell damage. LRG could upregulate the expression of NADPH oxidase 4 (NOX4). We also determined the increased NOX4 expression in kidney tissues of renal I/R-operated mice and H/R-treated HK-2 cells. NOX4 overexpression reversed the inhibitory role of LRG knockdown in HK-2 cell damage caused by H/R. Collectively, our findings demonstrate that LRG knockdown decreases the NOX4 expression, thereby alleviating renal I/R injury by inhibiting cell apoptosis, inflammation, and oxidative stress.

Vitamin B12 protects necrosis of acinar cells in pancreatic tissues with acute pancreatitis

Pharmacological agents regarding the most optimal treatments of acute pancreatitis remain. One-carbon metabolism nutrients as therapeutic agents in many diseases might be involved in acute pancreatitis. The roles are acquired exploration in acute pancreatitis. We utilized Mendelian randomization to assess the causal impact of folate, homocysteine, and vitamin B12 (VB12) on acute pancreatitis. Wild-type and corresponding genetically modified mouse models were used to verify the genetic correlating findings. A negative association between genetically predicted serum VB12 levels and risks of acute pancreatitis was identified in human population. The transcobalamin receptor (TCblR)/CD320 gene ablation that decreased cellular VB12 uptake and ATP production in pancreatic tissues promoted necrosis, resulting in much severe pathological changes of induced acute pancreatitis in mice. VB12 pretreatment and posttreatment dramatically increased ATP levels in pancreatic tissues and reduced the necrosis, then the elevated levels of amylase in serum, the levels of CK-19, the activity of trypsin, and T lymphocyte infiltration in pancreatic tissues, prevented the pancreatic gross loss and ameliorated histopathological changes of mouse pancreases with induced acute pancreatitis. The results reveal that VB12 is potential as a therapeutic agent to inhibit tissue injuries and adaptive inflammatory responses in the pancreas in patients with acute pancreatitis.

The Protective Effects of Vitamin B Complex on Diclofenac Sodium-Induced Nephrotoxicity: The Role of NOX4/RhoA/ROCK

Diclofenac sodium (DIC) is a widely used non-steroidal anti-inflammatory drug. Unfortunately, its prolonged use is associated with nephrotoxicity due to oxidative stress, inflammation, and fibrosis. We aimed to investigate the nephroprotective effects of vitamin B complex (B1, B6, B12) against DIC-induced nephrotoxicity and its impact on NOX4/RhoA/ROCK, a pathway that plays a vital role in renal pathophysiology. Thirty-two Wistar rats were divided into four groups: (1) normal control; (2) vitamin B complex (16 mg/kg B1, 16 mg/kg B6, 0.16 mg/kg B12, intraperitoneal); (3) DIC (10 mg/kg, intramuscular); and (4) DIC plus vitamin B complex group. After 14 days, the following were assayed: serum renal biomarkers (creatinine, blood urea nitrogen, kidney injury molecule-1), oxidative stress, inflammatory (tumor necrosis factor-α, interleukin-6), and fibrotic (transforming growth factor-β) markers as well as the protein levels of NOX4, RhoA, and ROCK. Structural changes, inflammatory cell infiltration, and fibrosis were detected using hematoxylin and eosin and Masson trichrome stains. Compared to DIC, vitamin B complex significantly decreased the renal function biomarkers, markers of oxidative stress and inflammation, and fibrotic cytokines. Glomerular and tubular damage, inflammatory infiltration, and excessive collagen accumulation were also reduced. Protein levels of NOX4, RhoA, and ROCK were significantly elevated by DIC, and this elevation was ameliorated by vitamin B complex. In conclusion, vitamin B complex administration could be a renoprotective approach during treatment with DIC via, at least in part, suppressing the NOX4/RhoA/ROCK pathway.

Vitamin B12 ameliorates gut epithelial injury via modulating the HIF-1 pathway and gut microbiota

Inflammatory bowel diseases (IBDs) are immune chronic diseases characterized by recurrent episodes, resulting in continuous intestinal barrier damage and intestinal microbiota dysbiosis. Safe strategies aimed at stabilizing and reducing IBDs recurrence have been vigorously pursued. Here, we constructed a recurrent intestinal injury Drosophila model and found that vitamin B12 (VB12), an essential co-factor for organism physiological functions, could effectively protect the intestine and reduce dextran sulfate sodium-induced intestinal barrier disruption. VB12 also alleviated microbial dysbiosis in the Drosophila model and inhibited the growth of gram-negative bacteria. We demonstrated that VB12 could mitigate intestinal damage by activating the hypoxia-inducible factor-1 signaling pathway in injured conditions, which was achieved by regulating the intestinal oxidation. In addition, we also validated the protective effect of VB12 in a murine acute colitis model. In summary, we offer new insights and implications for the potential supportive role of VB12 in the management of recurrent IBDs flare-ups.

Emerging Roles of Vitamin B12 in Aging and Inflammation

Vitamin B12 (cobalamin) is an essential nutrient for humans and animals. Metabolically active forms of B12-methylcobalamin and 5-deoxyadenosylcobalamin are cofactors for the enzymes methionine synthase and mitochondrial methylmalonyl-CoA mutase. Malfunction of these enzymes due to a scarcity of vitamin B12 leads to disturbance of one-carbon metabolism and impaired mitochondrial function. A significant fraction of the population (up to 20%) is deficient in vitamin B12, with a higher rate of deficiency among elderly people. B12 deficiency is associated with numerous hallmarks of aging at the cellular and organismal levels. Cellular senescence is characterized by high levels of DNA damage by metabolic abnormalities, increased mitochondrial dysfunction, and disturbance of epigenetic regulation. B12 deficiency could be responsible for or play a crucial part in these disorders. In this review, we focus on a comprehensive analysis of molecular mechanisms through which vitamin B12 influences aging. We review new data about how deficiency in vitamin B12 may accelerate cellular aging. Despite indications that vitamin B12 has an important role in health and healthy aging, knowledge of the influence of vitamin B12 on aging is still limited and requires further research.

Puerarin protects renal ischemia-reperfusion injury in rats through NLRP3/Caspase-1/GSDMD pathway

PURPOSE

To observe the effect of puerarin on renal ischemia-reperfusion (I/R) injury in rats, and to explore its mechanism based on NLRP3/Caspase-1/GSDMD pathway.

METHODS

Twenty-one Sprague-Dawley rats were divided into three groups: sham-operated group (sham), model group (RIRI), and puerarin treatment group (RIRI + Pue). The model of acute renal I/R injury was established by cutting the right kidney and clamping the left renal pedicle for 45 min.

RESULTS

Renal function parameters were statistically significant in group comparisons. The renal tissue structure of rats in sham group was basically normal. Pathological changes were observed in the RIRI group. The renal pathological damage score and apoptosis rate in the RIRI group were higher than those in the sham group, and significantly lower in the RIRI + Pue group than in the RIRI group. Indicators of oxidative stress-superoxide dismutase, malondialdehyde, and glutathione peroxidase-were statistically significant in group comparisons. Compared with the sham group, the relative expressions of NLRP3, Caspase-1 and GSDMD proteins in the RIRI group were increased. Compared with the RIRI group, the RIRI + Pue group had significant reductions.

CONCLUSIONS

Puerarin can inhibit the activation of NLRP3/Caspase-1/GSDMD pathway, inhibit inflammatory response and pyroptosis, and enhance the antioxidant capacity of kidney, thereby protecting renal I/R injury in rats.

Vitamin B12 alleviates myocardial ischemia/reperfusion injury via the SIRT3/AMPK signaling pathway

AIM

To examine the protective effect of vitamin B12 against myocardial ischemia/reperfusion (I/R) injury and elucidate its underlying mechanism of action.

METHODS

Mice were subjected to myocardial I/R injury by left anterior descending coronary artery (LAD) occlusion followed by 24 h reperfusion. Cardiac function and injury were evaluated by echocardiography, triphenyl tetrazolium chloride (TTC) and cardiac troponin T (cTnT) staining, and measuring lactate dehydrogenase (LDH) levels. In addition, various molecular and biochemical methods, as well as RNA sequencing were used to determine the effects and mechanism of action of vitamin B12 on I/R injury.

RESULTS

We found that high doses of vitamin B12 inhibited myocardial I/R injury. Furthermore, our data indicated that vitamin B12 supplementation alleviated cardiac dysfunction and injury by mitigating oxidative stress and apoptosis through downregulation of Nox2, the Ac-SOD2/SOD2 and Bax/Bcl-2 ratios and cleaved caspase-3 expression, and upregulation of SIRT3 expression and AMPK activity. However, these effects were largely reversed following treatment with the SIRT3 inhibitor, 3-TYP. Our RNA-sequencing data further demonstrated that vitamin B12 supplementation reduced inflammation during I/R injury.

CONCLUSION

High doses of vitamin B12 supplements improved myocardial I/R injury by suppressing the accumulation of reactive oxygen species and apoptosis of myocardial tissue through modulation of the SIRT3/AMPK signaling pathway, while reducing inflammation. Our findings suggested that vitamin B12 administered at high doses could be a potential therapy for myocardial I/R damage.

Methyl eugenol protects the kidney from oxidative damage in mice by blocking the Nrf2 nuclear export signal through activation of the AMPK/GSK3β axis

Disrupted redox homeostasis contributes to renal ischemia-reperfusion (IR) injury. Abundant natural products can activate nuclear factor erythroid-2-related factor 2 (Nrf2), thereby providing therapeutic benefits. Methyl eugenol (ME), an analog of the phenolic compound eugenol, has the ability to induce Nrf2 activity. In this study, we investigated the protective effects of ME against renal oxidative damage in vivo and in vitro. An IR-induced acute kidney injury (AKI) model was established in mice. ME (20 mg·kg-1·d-1, i.p.) was administered to mice on 5 consecutive days before IR surgery. We showed that ME administration significantly attenuated renal destruction, improved the survival rate, reduced excessive oxidative stress and inhibited mitochondrial lesions in AKI mice. We further demonstrated that ME administration significantly enhanced Nrf2 activity and increased the expression of downstream antioxidative molecules. Similar results were observed in vitro in hypoxia/reoxygenation (HR)-exposed proximal tubule epithelial cells following pretreatment with ME (40 μmol·L-1). In both renal oxidative damage models, ME induced Nrf2 nuclear retention in tubular cells. Using specific inhibitors (CC and DIF-3) and molecular docking, we demonstrated that ME bound to the binding pocket of AMPK with high affinity and activated the AMPK/GSK3β axis, which in turn blocked the Nrf2 nuclear export signal. In addition, ME alleviated the development of renal fibrosis induced by nonfatal IR, which is frequently encountered in the clinic. In conclusion, we demonstrate that ME modulates the AMPK/GSK3β axis to regulate the cytoplasmic-nuclear translocation of Nrf2, resulting in Nrf2 nuclear retention and thereby enhancing antioxidant target gene transcription that protects the kidney from oxidative damage.

Insulin Elevates ID2 Expression in Trophoblasts and Aggravates Preeclampsia in Obese ASB4-Null Mice

Obesity is a risk factor for preeclampsia. We investigated how obesity influences preeclampsia in mice lacking ankyrin-repeat-and-SOCS-box-containing-protein 4 (ASB4), which promotes trophoblast differentiation via degrading the inhibitor of DNA-binding protein 2 (ID2). Asb4^-/- mice on normal chow (NC) develop mild preeclampsia-like phenotypes during pregnancy, including hypertension, proteinuria, and reduced litter size. Wild-type (WT) and Asb4^-/- females were placed on a high-fat diet (HFD) starting at weaning. At the age of 8-9 weeks, they were mated with WT or Asb4^-/- males, and preeclamptic phenotypes were assessed. HFD-WT dams had no obvious adverse outcomes of pregnancy. In contrast, HFD-Asb4^-/- dams had significantly more severe preeclampsia-like phenotypes compared to NC-Asb4^-/- dams. The HFD increased white fat weights and plasma leptin and insulin levels in Asb4^-/- females. In the HFD-Asb4^-/- placenta, ID2 amounts doubled without changing the transcript levels, indicating that insulin likely increases ID2 at a level of post-transcription. In human first-trimester trophoblast HTR8/SVneo cells, exposure to insulin, but not to leptin, led to a significant increase in ID2. HFD-induced obesity markedly worsens the preeclampsia-like phenotypes in the absence of ASB4. Our data indicate that hyperinsulinemia perturbs the timely removal of ID2 and interferes with proper trophoblast differentiation, contributing to enhanced preeclampsia.

Association of Serum Homocysteine with Cardiovascular and All-Cause Mortality in Adults with Diabetes: A Prospective Cohort Study

Background

Homocysteine (Hcy) was implicated in oxidative stress and diabetes biologically. However, the clinical evidence on the link between Hcy level and diabetes is limited and controversial. This study is aimed at investigating the association of serum Hcy with all-cause and cardiovascular mortality in diabetic patients.

Methods

Serum Hcy was measured among 2,286 adults with type 2 diabetes in NHANES 1999-2006. Cox proportional hazard regression was used to estimate hazard ratios (HR) and 95% CIs for the association of Hcy with all-cause and cause-specific mortality.

Results

Over a median follow-up of 11.0 (interquartile range, 8.9-13.4) years, 952 of the 2286 patients with diabetes died, covering 269 (28.3%) cardiovascular deaths and 144 (15.2%) cancer deaths. Restricted cubic spline showed the linear relationship between Hcy and all-cause mortality risk. After multivariate adjustment, higher serum Hcy levels were independently associated with increased risk of all-cause and cardiovascular mortality. Compared with participants in the bottom tertile of Hcy, the multivariate-adjusted HRs and 95% CI for participants in the top quartile were 2.33 (1.64-3.30) for all-cause mortality (p_trend < 0.001), 2.24 (1.22-4.10) for CVD mortality (p_trend = 0.017), and 2.05 (0.90-4.69) for cancer mortality (p_trend = 0.096). The association with total mortality was especially stronger among patients with albuminuria. Serum Hcy significantly improved reclassification for 10-year mortality in diabetic patients (net reclassification index = 0.253 and integrated discrimination improvement = 0.011).

Conclusions

Serum Hcy was associated with risks of all-cause and cardiovascular mortality in diabetic adults. Our results suggested that Hcy was a promising biomarker in risk stratification among diabetic patients.

Cobinamide is a strong and versatile antioxidant that overcomes oxidative stress in cells, flies, and diabetic mice

Increased oxidative stress underlies a variety of diseases, including diabetes. Here, we show that the cobalamin/vitamin B₁₂ analog cobinamide is a strong and multifaceted antioxidant, neutralizing superoxide, hydrogen peroxide, and peroxynitrite, with apparent rate constants of 1.9 × 10⁸, 3.7 × 10⁴, and 6.3 × 10⁶ M^-1 s^-1, respectively, for cobinamide with the cobalt in the +2 oxidation state. Cobinamide with the cobalt in the +3 oxidation state yielded apparent rate constants of 1.1 × 10⁸ and 8.0 × 10² M^-1 s^-1 for superoxide and hydrogen peroxide, respectively. In mammalian cells and Drosophila melanogaster, cobinamide outperformed cobalamin and two well-known antioxidants, imisopasem manganese and manganese(III)tetrakis(4-benzoic acid)porphyrin, in reducing oxidative stress as evidenced by: (i) decreased mitochondrial superoxide and return of the mitochondrial membrane potential in rotenone- and antimycin A-exposed H9c2 rat cardiomyocytes; (ii) reduced JNK phosphorylation in hydrogen-peroxide-treated H9c2 cells; (iii) increased growth in paraquat-exposed COS-7 fibroblasts; and (iv) improved survival in paraquat-treated flies. In diabetic mice, cobinamide administered in the animals' drinking water completely prevented an increase in lipid and protein oxidation, DNA damage, and fibrosis in the heart. Cobinamide is a promising new antioxidant that has potential use in diseases with heightened oxidative stress.

Inhibition of PLK3 Attenuates Tubular Epithelial Cell Apoptosis after Renal Ischemia–Reperfusion Injury by Blocking the ATM/P53-Mediated DNA Damage Response

Objective

Renal ischemia–reperfusion (I/R) injury is a major cause of acute kidney injury (AKI) in transplanted kidneys. This study was aimed at exploring the role of PLK3 (polo-like kinase 3) in renal I/R injury, focusing on its relationship with oxidative stress-induced DNA damage and renal tubular epithelial cell (TEC) apoptosis.

Methods

TRAP-seq data from the development dataset GSE52004 and the validation dataset GSE121191 were analyzed using GEO2R. PLK3 overexpression plasmids and targeted silencing siRNAs were used in a model of hypoxia/reoxygenation (H/R) injury, and rAAV-9-PLK3-KD were administered to C57BL/6J mice exposed to I/R injury. The ATM-specific inhibitor KU-60019 was used to block the DNA damage response (DDR). Western blotting was performed to measure DDR- and apoptosis-associated protein expression. Cell viability was measured by CCK-8 reagent, and apoptosis was examined by flow cytometry and TUNEL assay. Furthermore, the fluorescent probes H₂DCFH-DA and DHE were used to measure ROS production in vitro. The MDA level and SOD activity were measured to assess oxidative stress in vivo. KIM-1 staining and Scr and BUN were used to evaluate kidney injury.

Results

The mRNA and protein levels of PLK3 were markedly increased in the H/R injury and I/R injury models. GO terms showed that PLK3 was mainly involved in oxidative stress and DNA damage after renal I/R injury. Overexpression of PLK3 decreased cell viability and increased apoptosis. In contrast, targeted silencing of PLK3 expression decreased the Bax/Bcl-2 ratio by decreasing P53 phosphorylation, thereby reducing TEC apoptosis. Furthermore, KU-60019 reduced PLK3 activation and DDR-induced apoptosis, while overexpression of PLK3 reversed the mitigating effect of KU-60019 on TEC apoptosis. Similarly, rAAV-9-PLK3 KD mice exhibited a lower rate of TEC apoptosis and milder renal damage after I/R injury.

Conclusion

We demonstrate for the first time that PLK3 is involved in oxidative stress-induced DNA damage and TEC apoptosis in renal I/R injury. Inhibition of PLK3 attenuates TEC apoptosis after I/R injury by blocking the ATM/P53-mediated DDR. Therefore, PLK3 may serve as a potential therapeutic target for ischemic AKI.

Vitamin B12 does not increase cell viability after hydrogen peroxide induced damage in mouse kidney proximal tubular cells and brain endothelial cells

Vitamin B12 (B12) is an essential co-factor for two enzymes in mammalian metabolism and can also act as a mimetic of superoxide dismutase (SOD) converting superoxide (O2 •‒) to hydrogen peroxide (H2O2). High oral dose B12 decreases renal O2 •‒ and post-ischemia/reperfusion injury in mice and protects against damage induced by hypoxia/reperfusion in mouse kidney proximal tubular cells (BU.MPT). O2 •‒ is unstable and rapidly converted to H2O2. H2O2 mediates oxidative stress associated with O2 •‒. Whether B12 protects against damage induced by H2O2 is unknown. Both BU.MPT cells and mouse brain endothelial cells (bEdn.3) were applied to test the effects of B12 on H2O2-induced cytotoxicity. Both types of cells were treated with different doses of H2O2 with or without different doses of B12. Cell viability was analyzed 24 h later. H2O2 caused cell death only at a very high dose, and high pharmacological dose of B12 did not prevent this detrimental effect in either cell type. In bEnd.3 cells, transcriptional levels of heme oxygenase-1 (HO-1) increased, while nuclear factor erythroid 2-related factor 2 (Nrf2) decreased by H2O2. The levels of transcripts were not affected by the B12 treatment. We conclude that the cytotoxic effects of exogenous H2O2 in BU.MPT and bEdn.3 cells are not prevented by B12.

Vitamin B12 and chronic kidney disease

Chronic Kidney Disease (CKD) is an emerging public health issue with a fast-growing global prevalence. Impairment in vitamin B12 metabolism is considered a nontraditional risk factor of poor outcomes associated with CKD, and there is greater interest from the scientific community than ever before to explore the role and influence of vitamin B12 in CKD. Homocysteine metabolism forms an important component of the vitamin B12 metabolic pathway. Hyperhomocysteinemia is frequently observed in CKD and End-Stage Kidney Disease (ESKD), but its representation as a prognostic marker for CKD outcomes is still not fully clear. This chapter reviews the vitamin B12 and homocysteine metabolic pathways and their dysfunction in CKD states. Biochemical factors and the MTHFR genetic polymorphisms which disrupt vitamin B12 and homocysteine metabolism are explored. The mechanisms of homocysteine-mediated and vitamin B12-mediated tissue damage in CKD are discussed. This chapter reviews current perspective on definition and measurement of plasma vitamin B12 levels in the CKD population. Updated evidence investigating the prognostic role of vitamin B12 for CKD outcomes is presented. Findings from major clinical trials conducted relating to outcomes from multivitamin (including folic acid and vitamin B12) supplementation in nondialysis and dialysis-dependent CKD are highlighted. The prognostic value of vitamin B12 and effects of vitamin B12 supplementation in the context of kidney transplantation and acute kidney injury is also reviewed. Future research considerations are summarized based on evidence gaps in our knowledge base of this topic. Greater abundance of high-level evidence to guide an approach toward vitamin B12 measurement, monitoring and supplementation in CKD may contribute to improved clinical outcomes.

Exploring the Immune-Boosting Functions of Vitamins and Minerals as Nutritional Food Bioactive Compounds: A Comprehensive Review

Food components have long been recognized to play a fundamental role in the growth and development of the human body, conferring protective functionalities against foreign matter that can be severe public health problems. Micronutrients such as vitamins and minerals are essential to the human body, and individuals must meet their daily requirements through dietary sources. Micronutrients act as immunomodulators and protect the host immune response, thus preventing immune evasion by pathogenic organisms. Several experimental investigations have been undertaken to appraise the immunomodulatory functions of vitamins and minerals. Based on these experimental findings, this review describes the immune-boosting functionalities of micronutrients and the mechanisms of action through which these functions are mediated. Deficiencies of vitamins and minerals in plasma concentrations can lead to a reduction in the performance of the immune system functioning, representing a key contributor to unfavorable immunological states. This review provides a descriptive overview of the characteristics of the immune system and the utilization of micronutrients (vitamins and minerals) in preventative strategies designed to reduce morbidity and mortality among patients suffering from immune invasions or autoimmune disorders.

Vitamin B12 Attenuates Acute Pancreatitis by Suppressing Oxidative Stress and Improving Mitochondria Dysfunction via CBS/SIRT1 Pathway

Acute pancreatitis is an inflammatory disorder of the pancreas associated with substantial morbidity and mortality, which is characterized by a rapid depletion of glutathione (GSH). Cysthionine-β-synthase (CBS) is a key coenzyme in GSH synthesis, and its deficiency is related to a variety of clinical diseases. However, whether CBS is involved in the pathogenesis of acute pancreatitis remains unclear. First, we found that CBS was downregulated in both in vivo and in vitro AP models. The pancreatic damage and acinar cell necrosis related to CBS deficiency were significantly improved by VB 12, which stimulated clearance of reactive oxygen species (ROS) by conserving GSH. Furthermore, EX-527 (a specific inhibitor of SIRT1) exposure counteracted the protective effect of VB 12 by promoting oxidative stress and aggravating mitochondrial damage without influencing CBS, indicating that vitamin B₁₂ regulates SIRT1 to improve pancreatical damage by activating CBS. In conclusion, we found that VB 12 protected acute pancreatitis associated with oxidative stress via CBS/SIRT1 pathway.

Riclinoctaose Attenuates Renal Ischemia-Reperfusion Injury by the Regulation of Macrophage Polarization

Renal ischemia-reperfusion injury is a major trigger of acute kidney injury and leads to permanent renal impairment, and effective therapies remain unresolved. Riclinoctaose is an immunomodulatory octasaccharide composed of glucose and galactose monomers. Here we investigated whether riclinoctaose protects against renal ischemia-reperfusion injury. In mice, pretreatment with riclinoctaose significantly improved renal function, structure, and the inflammatory response after renal ischemia-reperfusion. Flow cytometry analysis revealed that riclinoctaose inhibited ischemia-reperfusion-induced M1 macrophage polarization and facilitated M2 macrophage recruitment into the kidneys. In isolated mouse bone marrow-derived macrophages, pretreatment with riclinoctaose promoted the macrophage polarization toward M2-like phenotype. The inhibitor of Nrf-2/HO-1 brusatol diminished the effects of riclinoctaose on macrophage polarization. In mice, intravenous injection with riclinoctaose-pretreated bone marrow-derived macrophages also protected against renal ischemia-reperfusion injury. Fluorescence-labeled riclinoctaose specifically bound to the membrane of macrophages. Interfering with mDC-SIGN blocked the riclinoctaose function on M2 polarization of macrophages, consequently impairing the renoprotective effect of riclinoctaose. Our results revealed that riclinoctaose is a potential therapeutic agent in preventing renal ischemia-reperfusion injury.

MicroRNA-214-5p aggravates sepsis-related acute kidney injury in mice

Acute kidney injury (AKI) is a devastating comorbidity in sepsis and correlates with a very poor prognosis and increased mortality. Currently, we use lipopolysaccharide (LPS) to establish sepsis-related AKI and try to demonstrate the pathophysiological role of microRNA-214-5p (miR-214-5p) in this process. Mice were intravenously injected with the miR-214-5p agomir, antagomir or negative controls for three consecutive days and then received a single intraperitoneal injection of LPS (10 mg/kg) for 24 h to induce AKI. Besides, the Boston University mouse proximal tubular cell lines were stimulated with LPS (10 μg/ml) for 8 h to investigate the role of miR-214-5p in vitro. To inhibit adenosine monophosphate-activated protein kinase (AMPK), compound C (CpC) was used in vivo. For glucagon-like peptide-1 receptor (GLP-1R) silence, cells were transfected with the small interfering RNA against GLP-1R. miR-214-5p level was upregulated in LPS-treated kidneys and proximal tubular cell lines. The miR-214-5p antagomir reduced LPS-induced renal inflammation and oxidative stress, thereby preventing renal damage and dysfunction. In contrast, the miR-214-5p agomir aggravated LPS-induced inflammation, oxidative stress and AKI in vivo and in vitro. Mechanistically, we found that the miR-214-5p antagomir prevented septic AKI via activating AMPK and that CpC treatment completely abrogated its renoprotective effect in mice. Further detection showed that miR-214-5p directly bound to the 3'-untranslational region of GLP-1R to inhibit GLP-1R/AMPK axis. Our data identify miR-214-5p as a promising therapeutic candidate to treat sepsis-related AKI.

The beneficial role of vitamin B12 in injury induced by ischemia/reperfusion: Beyond scavenging superoxide?

Vitamin B12 (B12) is required for cellular metabolism and DNA synthesis as a co-enzyme; it also possesses anti-reactive oxygen species (ROS) property as a superoxide scavenger. B12 deficiency has been implicated in multiple diseases such as megaloblastic anemia, and this disease can be effectively cured by supplementation of B12. Multiple studies suggest that B12 also benefits the conditions associated with excess ROS. Recently, we have reported that oral high dose B12 decreases superoxide level and renal injury induced by ischemia/reperfusion in mice. Here, we discuss potential mechanism(s) other than decreasing superoxide by which B12 executes its beneficial effects.

Cyanocobalamin prevents cardiomyopathy in type 1 diabetes by modulating oxidative stress and DNMT-SOCS1/3-IGF-1 signaling

Patients with long-standing diabetes have a high risk for cardiac complications that is exacerbated by increased reactive oxygen species (ROS) production. We found that feeding cyanocobalamin (B12), a scavenger of superoxide, not only prevented but reversed signs of cardiomyopathy in type 1 diabetic Elmo1^H/H Ins2^Akita/+ mice. ROS reductions in plasma and hearts were comparable to those in mice treated with other antioxidants, N-acetyl-L-cysteine or tempol, but B12 produced better cardioprotective effects. Diabetes markedly decreased plasma insulin-like growth factor (IGF)-1 levels, while B12, but not N-acetyl-L-cysteine nor tempol, restored them. B12 activated hepatic IGF-1 production via normalization of S-adenosylmethionine levels, DNA methyltransferase (DNMT)-1/3a/3b mRNA, and DNA methylation of promoters for suppressor of cytokine signaling (SOCS)-1/3. Reductions of cardiac IGF-1 mRNA and phosphorylated IGF-1 receptors were also restored. Thus, B12 is a promising option for preventing diabetic cardiomyopathy via ROS reduction and IGF-1 retrieval through DNMT-SOCS1/3 signaling.

Dl-3-n-butylphthalide pretreatment attenuates renal ischemia/reperfusion injury

BACKGROUND

Renal ischemia reperfusion injury (IRI) has become a growing concern in clinical practice with high morbidity and mortality rates. There is currently no effective prophylactic regimen available to prevent its occurrence and to improve its clinical prognosis. Dl-3-n-butylphthalide (NBP) has been used for stroke treatment in China for years. Little is known about its role in preventing kidney injury.

METHODS

The kidneys of male C57BL/6J mice were subjected to 33 min of ischemia followed by 24 h of reperfusion. NBP was administered by gavage prior to surgery. The reno-protective effect of NBP was evaluated by serum creatinine, kidney injury markers and renal pathological changes. Furthermore, the inflammation, oxidative stress, and apoptosis markers in kidney tissue were examined. In vitro, HK2 cells were treated prophylactically with NBP and then exposed to hypoxia/reoxygenation (H/R). Cell viability and apoptosis related protein were quantified to verify the protective effect of NBP. Pro-inflammation genes expression as well as ROS generation were further investigated also.

RESULTS

NBP pretreatment significantly improved renal dysfunction and alleviated pathological injury, renal inflammation response, oxidative stress and cell apoptosis. Consistently, NBP attenuated H/R induced increases in ROS, pro-inflammatory genes expression, apoptosis and cleaved caspase-3 levels in HK2 cells.

CONCLUSION

Our promising results validated for the first time that NBP could ameliorate renal IRI via attenuating inflammation, oxidative stress, and apoptosis, which indicated that NBP might be a good candidate against AKI.

Beneficial effects of nicotinamide on hypertensive mice with impaired endothelial nitric oxide function

Nicotinamide (Nam, amide form of niacin acid or nicotinate), a precursor for nicotinamide adenine dinucleotide (NAD+), is important for normal physiological function of organisms. Nam also suppresses mobilization of Ca²⁺ from sarcoplasmic reticulum into cytoplasm through inhibiting ADP-ribose cyclase. Previously, we have demonstrated that a pharmacological dose of Nam normalizes maternal blood pressure in mouse models of preeclampsia, a pregnancy related hypertensive disorder. We hypothesized that Nam could decrease blood pressure in hypertensive conditions unrelated to pregnancy. Nam at a dose of 500 mg/kg/day was given to wild type (WT) mice treated with L-NAME, endothelial nitric oxide synthase (eNOS)-null and renin transgenic (Renin-Tg) mice via drinking water. Blood pressure was measured by tail-cuff at different stages of treatment. The function and structure of kidneys of WT mice with L-NAME were determined at the end of the study. The gene expression of markers of inflammation and fibrosis in the kidneys of WT mice with L-NAME was also measured. Nam effectively prevented increase in blood pressure in L-NAME treated mice and decreased elevated blood pressure in eNOS-null mice. However, it did not alter high blood pressure in Renin-Tg mice. Nam prevented increase in urinary albumin excretion and collagen deposit in kidneys of WT mice treated with L-NAME. In addition, Nam significantly decreased the mRNA levels of the markers of inflammation and fibrosis in the kidneys of WT mice treated with L-NAME. Nam may execute beneficial effects on hypertensive conditions associated with eNOS dysfunction via suppressing inflammation. Because Nam is generally regarded as safe in humans, it merits further evaluation for the tailored treatment for the subgroup of hypertensive cases associated with impaired eNOS system.