Magnesium sulfate suppresses inflammatory responses by human umbilical vein endothelial cells (HuVECs) through the NFkappaB pathway

Pretreatment with magnesium ameliorates lipopolysaccharide-induced liver injury in mice

BACKGROUND

Lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, is involved in the pathogenesis of sepsis. LPS administration induces systemic inflammation that mimics many of the initial clinical features of sepsis and has deleterious effects on several organs including the liver and eventually leading to septic shock and death. The present study aimed to investigate the protective effect of magnesium (Mg), a well known cofactor in many enzymatic reactions and a critical component of the antioxidant system, on hepatic damage associated with LPS-induced endotoxima in mice.

METHODS

Mg (20 and 40mg/kg, po) was administered for 7 consecutive days. Systemic inflammation was induced 1h after the last dose of Mg by a single dose of LPS (2mg/kg, ip) and 3h thereafter plasma was separated, animals were sacrificed and their livers were isolated.

RESULTS

LPS-treated mice suffered from hepatic dysfunction revealed by histological observation, elevation in plasma transaminases activities, C-reactive protein content and caspase-3, a critical marker of apoptosis. Liver inflammation was evident by elevation in liver cytokines contents (TNF-α and IL-10) and MPO activity. Additionally, oxidative stress was manifested by increased liver lipoperoxidation, glutathione depletion, elevated total nitrate/nitrite (NOx) content and glutathione peroxidase (GPx) activity. Pretreatment with Mg largely mitigated these alternations.

CONCLUSION

Pretreatment with Mg protects the liver from the acute injury which occurs shortly after septicemia.

In vitro and in vivo biocompatibility and corrosion behaviour of a bioabsorbable magnesium alloy coated with octacalcium phosphate and hydroxyapatite

Octacalcium phosphate (OCP) and hydroxyapatite (HAp) coatings were formed on Mg-3 mass% Al-1 mass% Zn (AZ31) magnesium alloy by a single-step chemical solution deposition method. Chemically polished AZ31 (Cpol-AZ31) and HAp- and OCP-coated AZ31 (HAp- and OCP-AZ31) were immersed in a medium for 52 weeks or implanted in transgenic mice for 16 weeks to examine the long-term corrosion behaviour and in situ inflammation behaviour. In the medium, Mg-ion release was restricted for the initial several days and the corrosion rate thereafter was suppressed by approximately one-half with the HAp and OCP coatings. HAp-AZ31 showed a ∼20% lower corrosion rate than OCP-AZ31. Tissues of the transgenic mouse emit fluorescence in proportion to the degree of inflammation in situ. The luminescence intensity level was too low to be a problem regardless of the coatings. A thinner fibrous tissue layer was formed around OCP- and HAp-AZ31 than around Cpol-AZ31, indicating that the HAp and OCP coatings suppressed corrosion and foreign-body reaction in vivo. Visible pits were formed in filiform and round shapes in vitro and in vivo, respectively. Corrosion was observed underneath the coatings, and almost uniform corrosion took place in vitro, while local corrosion was predominant in vivo. These differences in corrosion morphology are attributed to the adhesion of tissues and the lower diffusivity on the surface in vivo than that in vitro. Dissolution behaviour of OCP crystals in vivo was different from that in vitro. It was demonstrated that the HAp and OCP coatings developed have great potential for a biocompatible and corrosion protection coating.

Magnesium sulfate treatment reverses seizure susceptibility and decreases neuroinflammation in a rat model of severe preeclampsia

Eclampsia, defined as unexplained seizure in a woman with preeclampsia, is a life-threatening complication of pregnancy with unclear etiology. Magnesium sulfate (MgSO₄) is the leading eclamptic seizure prophylactic, yet its mechanism of action remains unclear. Here, we hypothesized severe preeclampsia is a state of increased seizure susceptibility due to blood-brain barrier (BBB) disruption and neuroinflammation that lowers seizure threshold. Further, MgSO₄ decreases seizure susceptibility by protecting the BBB and preventing neuroinflammation. To model severe preeclampsia, placental ischemia (reduced uteroplacental perfusion pressure; RUPP) was combined with a high cholesterol diet (HC) to cause maternal endothelial dysfunction. RUPP+HC rats developed symptoms associated with severe preeclampsia, including hypertension, oxidative stress, endothelial dysfunction and fetal and placental growth restriction. Seizure threshold was determined by quantifying the amount of pentylenetetrazole (PTZ; mg/kg) required to elicit seizure in RUPP+HC±MgSO₄ and compared to normal pregnant controls (n = 6/group; gestational day 20). RUPP+HC rats were more sensitive to PTZ with seizure threshold being ∼65% lower vs. control (12.4±1.7 vs. 36.7±3.9 mg/kg PTZ; p<0.05) that was reversed by MgSO₄ (45.7±8.7 mg/kg PTZ; p<0.05 vs. RUPP+HC). BBB permeability to sodium fluorescein, measured in-vivo (n = 5–7/group), was increased in RUPP+HC vs. control rats, with more tracer passing into the brain (15.9±1.0 vs. 12.2±0.3 counts/gram ×1000; p<0.05) and was unaffected by MgSO₄ (15.6±1.0 counts/gram ×1000; p<0.05 vs. controls). In addition, RUPP+HC rats were in a state of neuroinflammation, indicated by 35±2% of microglia being active compared to 9±2% in normal pregnancy (p<0.01; n = 3–8/group). MgSO₄ treatment reversed neuroinflammation, reducing microglial activation to 6±2% (p<0.01 vs. RUPP+HC). Overall, RUPP+HC rats were in a state of augmented seizure susceptibility potentially due to increased BBB permeability and neuroinflammation. MgSO₄ treatment reversed this, increasing seizure threshold and decreasing neuroinflammation, without affecting BBB permeability. Thus, reducing neuroinflammation may be one mechanism by which MgSO₄ prevents eclampsia during severe preeclampsia.

Domino effect of hypomagnesemia on the innate immunity of Crohn’s disease patients

Digestive diseases play major role in development and complications of other disorders including diabetes. For example, Crohn’s disease (CD) is an inflammatory bowel disease associated with Mycobacterium avium subspecies paratuberculosis. The inflammation is a complex process that involves the activity of both innate and adaptive immune responses. CD lesions are primarily due to T cell response, however; innate immune response has a significant role in initiating its pathogenesis. Toll-like receptors and NOD-like receptors promote the activity of nuclear factor (NF)-κB pathway for cytokines production. This results in the production of high levels of tumor necrosis factor-α, interleukin (IL)-1β and IL-6. Moreover, intestinal inflammation of CD is related to increased activity of NMDA receptors and the release of substance P. Imbalanced magnesium homeostasis in CD is a frequent finding in CD, Diabetes and others. The loss of such a major mineral affects many physiological processes in the body including its role as an immunomodulator. This review aims to (1) describe the significance of hypomagnesemia in the release of pro-inflammatory mediators in CD; (2) demonstrate effects of magnesium on pathways like NF-κB; (3) address the role of hypomagnesemia in the activity of CD; and (4) examine possible future research to establish a standard magnesium supplementation strategy; helping patients with CD or other disorders to maintain a sustained remission.

Intravenous magnesium for pediatric sickle cell vaso-occlusive crisis: methodological issues of a randomized controlled trial

Multiple recent Sickle Cell Disease studies have been terminated due to poor enrollment. We developed methods to overcome past barriers and utilized these to study the efficacy and safety of intravenous magnesium for vaso-occlusive crisis (VOC). We describe the methods of the Intravenous Magnesium in Sickle Vaso-occlusive Crisis (MAGiC) trial and discuss methods used to overcome past barriers. MAGiC was a multi-center randomized double-blind placebo-controlled trial of intravenous magnesium versus normal saline for treatment of VOC. The study was a collaboration between Pediatric Hematologists and Emergency Physicians in the Pediatric Emergency Care Applied Research Network (PECARN). Eligible patients were randomized within 12 hours of receiving intravenous opioids in the Emergency Department (ED) and administered study medication every 8 hours. The primary outcome was hospital length of stay. Associated plasma studies elucidated magnesium's mechanism of action and the pathophysiology of VOC. Health-related quality of life was measured. Site-, protocol-, and patient-related barriers from prior studies were identified and addressed. Limited study staff availability, lack of collaboration with the ED, and difficulty obtaining consent were previously identified barriers. Leveraging PECARN resources, forging close collaborations between Sickle Cell Centers and EDs of participating sites, and approaching eligible patients for prior consent helped overcome these barriers. Participation in the PECARN network and establishment of collaborative arrangements between Sickle Cell Centers and their affiliated EDs are major innovative features of the MAGiC study that allowed improved subject capture. These methods could serve as a model for future studies of VOCs.

Biodegradation of metallic magnesium elicits an inflammatory response in primary nasal epithelial cells

Resorbable magnesium-based implants hold great promise for various biomedical applications, such as osteosynthesis and coronary stenting. They also offer a new therapeutic option for the treatment of chronic rhinosinusitis, but little data is yet available regarding the use of magnesium in the nasal cavity. To model this field of application, primary porcine nasal epithelial cells were used to test the biocompatibility of degrading pure magnesium and investigate whether the degradation products may also affect cellular metabolism. Magnesium specimens did not induce apoptosis and we found no major influence on enzyme activities or protein synthesis, but cell viability was reduced and elevated interleukin 8 secretion indicated proinflammatory reactions. Necrotic damage was most likely due to osmotic stress, and our results suggest that magnesium ion build-up is also involved in the interleukin 8 release. Furthermore, the latter seems to be mediated, at least in part, by the p38 signaling pathway. These effects probably depended on the accumulation of very high concentrations of magnesium ions in the in vitro set-up, which might not be achieved in vivo, although we cannot exclude that further, as yet unknown, factors played a role in the inflammatory response during the degradation process. In conclusion, the biocompatibility of pure magnesium with cells in the immediate vicinity appears less ideal than is often supposed, and this needs to be considered in the evaluation of magnesium materials containing additional alloying elements.

Effect of dexamethasone administered with magnesium sulfate on inflammation-mediated degradation of the blood-brain barrier using an in vitro model

Patients at risk for preterm delivery are frequently administered both antenatal steroids for fetal maturation and magnesium sulfate for neuroprotection. In this study, we investigate whether steroids coadministered with magnesium sulfate preserve blood-brain barrier integrity in neuroinflammation. Human umbilical vein endothelial cells were grown in astroglial conditioned media in a 2-chamber cell culture apparatus. Treatment with tumor necrosis factor-α (TNF-α) or catalytically active recombinant matrix metalloproteinase 9 (MMP-9) simulated neuroinflammation. Membrane integrity was assessed by zona occludens 1 (ZO-1) immunoreactivity, permeability to fluorescently conjugated dextran, and transendothelial electrical resistance (TEER). The TNF-α and MMP-9 treatment increased the rate of dextran transit, decreased TEER, and decreased ZO-1 immunoreactivity at junctional interfaces. Dexamethasone pretreatment alone or in combination with 0.5 mmol/L magnesium sulfate preserved monolayer integrity after inflammatory insult. Magnesium sulfate alone was not protective. This study supports a possible interaction between steroids and magnesium in neuroprotection.

Maternal magnesium supplementation reduces intrauterine growth restriction and suppresses inflammation in a rat model

OBJECTIVE

Intrauterine growth restriction (IUGR) is associated with increased inflammatory responses. We sought to investigate whether magnesium (Mg) attenuates inflammation and IUGR in a rat model.

STUDY DESIGN

Pregnant Wistar rats (12 weeks, gestational day 18) were randomly assigned to 1 of 4 groups: normal diet with bilateral uterine artery ligation (BL) (n = 6) or sham surgery (SH) (n = 5); and Mg chloride (MgCl2) 1% (wt/vol) in the drinking water throughout gestation + BL (MgBL) (n = 6) or SH (MgSH) (n = 5). Dams were euthanized 24 hours postsurgery (gestational day 19). Maternal plasma, fetal plasma (pooled), individual amniotic fluid (AF) samples, and placentas (PL) were collected and assessed from live fetal pups only (BL, n = 36; SH, n = 20; MgBL, n = 20; MgSH, n = 20). All samples were analyzed for cytokines/chemokines (interleukin [IL]-6, IL-1β, chemokine [C-X-C motif] ligand 1 [CXCL1], chemokine [C-C motif] ligand 2 [CCL2], and tumor necrosis factor [TNF-α] sensitivity <3 pg/mL) using a multiplex platform. Data were analyzed using Mann Whitney, analysis of variance, and Fisher exact tests.

RESULTS

The incidence of IUGR (pup weight <10th percentile of SH) in the MgBL group was significantly lower (31%) than the BL group (86.3%) (relative risk, 0.36; 95% confidence interval, 0.2-0.6; P < .0001). BL significantly increased AF levels of IL-6, IL-1β, TNF-α (P < .05), and CCL2 (P < .001) vs SH and PL levels of IL-6, IL-1β, CCL2 and CXCL1 (P < .001), and TNF-α (P < .05) vs SH. Maternal MgCl2 supplementation significantly decreased IL-1β, TNF-α, and CCL2 levels in AF and IL-1β in PL tissues of MgBL vs BL rats (P < .0001).

CONCLUSION

Maternal oral MgCl2 supplementation reduced BL-induced IUGR by 64% and suppressed cytokine/chemokine levels in the AF and PL.

The efficacy of magnesium sulfate loading on microalbuminuria following SIRS: One step forward in dosing

Backgrounds

Magnesium has been known for its antioxidative and antiinflammatory properties in many studies. In this study two dosing regimens of magnesium were compared with a placebo control group in order to investigate safety and efficacy of high doses of intravenous magnesium sulfate infusion on critically ill trauma patients. Inflammatory and oxidative factors were measured in this trial.

Methods

45 trauma patients with systemic inflammatory response syndromes (SIRS) were randomly assigned into 2 treatment and one placebo groups. The high dose group received 15 g MgSO₄, low dose group received 7.5 g of MgSO₄ over 4 hour infusion, and placebo group received saline alone. The initial and post magnesium sulfate injections levels of tumor necrosis factor alpha (TNF-α), total antioxidant power and lipid peroxidation were measured after 6, 18 and 36 hours. The pre-infusion along with 6 and 36 hour level of microalbuminuria were also determined.

Results

Repeated measurements illustrated that there was no significant difference in TNF-α, total antioxidant power and lipid peroxidation levels among groups during the period of analysis. The microalbuminuria at 36 hour post infusion of high dose group was lower than that of control group (p = 0.024). Patient’s mortality (28 day) was similar among all treatment groups. Both magnesium infusion groups tolerated the drug without experiencing any complications.

Conclusion

No evidence for antioxidative and antiinflammatory effects of magnesium in traumatic SIRS positive patients was found. Magnesium in high doses may be recommended for traumatic patients with SIRS status to prevent microalbuminuria.

[Use of magnesium sulfate in obstetrics]

Magnesium sulfate (MgSO(4)) is the best treatment of eclampsia, reduces the risk of recurrence better than other anticonvulsants and is recommended as first line in cases of eclampsia. In cases of severe pre-eclampsia and especially when prodromes are present, MgSO(4) reduces better than conventional anticonvulsants the risk of eclampsia. More recently, MgSO(4) was used in cases of preterm delivery to reduce the risk of cerebral palsy in premature infants. Three large randomized trials have obtained convergent results which all tended to show a neuroprotective effect of MgSO(4). These trials were included in three meta-analyzes that showed a 30% reduction in the incidence of cerebral palsy before 32 weeks gestation suggesting that this drug should be used in cases of preterm birth. A protocol using low doses associated with a well-conducted maternal surveillance reduces of maternal hypermagnesemia and the risk of maternal toxicity.

Placental secretion of interleukin-1 and interleukin-1 receptor antagonist in preeclampsia: effect of magnesium sulfate

Preeclampsia is a pregnancy-specific disorder characterized by hypertension and systemic endothelial dysfunction. Interleukin (IL)-1β is a possible mediator of maternal endothelial dysfunction in preeclampsia. Serum IL-1β as well as its natural inhibitor IL-1 receptor antagonist (IL-1Ra) were reported to be increased in women with preeclampsia. In the current study, we addressed the role of the placenta in controlling the circulatory levels of IL-1β and its natural inhibitor IL-1Ra in preeclampsia, and the possible effect of magnesium sulfate (MgSO(4)) on these levels. Using an ex vivo placental perfusion system, placentas from preeclamptic (n = 9) and normotensive (n = 6) pregnancies were perfused in presence or absence of MgSO(4). Perfusate samples were collected from the maternal and the fetal circulations of the perfusion system, and IL-1β and IL-1Ra were examined by enzyme-linked immunoassay (ELISA). Preeclamptic placentas secreted higher levels of IL-1β (P < 0.001), and a tendentious higher levels of IL-1Ra, mainly into the maternal circulation, as compared with normotensive placentas, although no differences in IL-1β:IL-1Ra ratio were detected. However, there was only tendentious increase in the secretion levels of IL-1β or IL-1Ra into the fetal circulation of preeclamptic placentas, when compared with normotensive placentas. Administration of MgSO(4) to preeclamptic placentas resulted in an attenuation of the increased secretion of IL-1β into the maternal circulation (P < 0.001), and in a tendentious reduction in IL-1Ra. However, IL-1β:IL-1Ra ratio in preeclamptic placentas was not affected by MgSO(4). Interestingly, exposure of normotensive placenta to MgSO(4) resulted only in increased levels of IL-1Ra in the maternal circulation, without affecting IL-1β levels or IL-1β:IL-1Ra ratio. These findings suggest that the placenta may contribute to the elevation in serum IL-1β and IL-1Ra in preeclampsia by increased secretion of these cytokines into the maternal circulation, and that MgSO(4) is able to attenuate this increased secretion of IL-1β, and possibly IL-1Ra, in preeclampsia.

Magnesium sulfate inhibits the secretion of high mobility group box 1 from lipopolysaccharide-activated RAW264.7 macrophages in vitro

BACKGROUND

High mobility group box 1 (HMGB1) is an important inflammatory factor that is closely related to mortality in patients with sepsis. High magnesium therapy has been proved to reduce sepsis-related mortality and sepsis-induced pathologic complications. These effects result from reduced expression and release of many inflammatory cytokines, although it is not clear whether high magnesium affects the expression and release of HMGB1. In the present study, we explored the effect of magnesium sulfate on the expression and release of HMGB1 in lipopolysaccharide (LPS)-activated macrophages.

METHODS

RAW264.7 cells were incubated with LPS in the presence or absence of various concentrations of magnesium sulfate. An enzyme-linked immunosorbent assay was used to detect the levels of HMGB1 in the culture supernatant. Real-time polymerase chain reaction was used to assess the expression of HMGB1 mRNA. The nuclear/cytoplasm extraction kit was used to extract the nuclear and cytoplasmic proteins. Western blotting was used to observe the changes in the translocation of HMGB1 from the nucleus to the cytoplasm. The nuclear factor (NF)-κB p50/p65 Transcription Factor Assay Kit was used to analyze NF-κB activity in the nuclear extract.

RESULTS

We found that magnesium sulfate inhibited translocation of HMGB1 from the nucleus to the cytoplasm and its extracellular release in LPS-activated macrophages and also suppressed the expression of HMGB1 mRNA. Furthermore, magnesium sulfate inhibited the translocation of NF-κB from the cytoplasm to the nucleus in LPS-activated macrophages in a dose-dependent manner.

CONCLUSIONS

Our study has demonstrated that magnesium sulfate inhibits the translocation of HMGB1 from the nucleus to the cytoplasm and the expression of HMGB1 mRNA in a dose-dependent manner. The mechanism responsible for these effects involves the NF-κB signaling pathway.

Endothelial cells and magnesium: implications in atherosclerosis

There is no doubt that the functional and structural integrity of the endothelium is critical in maintaining vascular homoeostasis and in preventing atherosclerosis. In the light of epidemiological and experimental studies, magnesium deficiency is emerging as an inducer of endothelial dysfunction. In particular, data on the effects of low extracellular magnesium on cultured endothelial cells reinforce the idea that correcting magnesium homoeostasis might be a helpful and inexpensive intervention to prevent and treat endothelial dysfunction and, consequently, atherosclerosis.

Thrombotic microangiopathy: a role for magnesium?

Despite advances in more recent years, the pathophysiology and especially treatment modalities of thrombotic microangiopathy (TMA) largely remain enigmatic. Disruption of endothelial homeostasis plays an essential role in TMA. Considering the proven causal association between magnesium and both endothelial function and platelet aggregability, we speculate that a magnesium deficit could influence the course of TMA and the related haemolytic uraemic syndrome and thrombotic thrombocytopenic purpura. A predisposition towards TMA is seen in many conditions with both extracellular and intracellular magnesium deficiency. We propose a rationale for magnesium supplementation in TMA, in analogy with its evidence-based therapeutic application in pre-eclampsia and suggest, based on theoretical grounds, that it might attenuate the development of TMA, minimise its severity and prevent its recurrence. This is based on several lines of evidence from both in vitro and in vivo data showing dose-dependent effects of magnesium supplementation on nitric oxide production, platelet aggregability and inflammation. Our hypothesis, which is further amenable to assessment in animal models before therapeutic applications in humans are implemented, could be explored both in vitro and in vivo to decipher the potential role of magnesium deficit in TMA and of the effects of its supplementation.

Chemokines plasma levels in preterm newborns of preeclamptic mothers

Information on leukocyte activation in newborn infants of preeclamptic mothers is scarce. IL-8 and GRO-α are the main pro-inflammatory cytokines involved in leukocyte activation. The objective was to evaluate IL-8 and GRO-α plasma levels in preterm newborns infants of preeclamptic mothers. Newborns with gestational age<36 weeks and birth weight<2000 g were included and divided: non-preeclamptic (n=64) and preeclamptic groups (n=55). Exclusion criteria were major congenital malformations, inborn errors of metabolism or chromosomal anomalies, congenital infections, death in delivery room, and maternal chronic hypertension without preeclampsia. IL-8 and GRO-α were measured by enzyme immunoassay in the first 48 h. Groups were similar in birth weight, gestational age, Apgar scores at 5 min, sepsis, RDS, mechanical ventilation, TPN, NEC, intraventricular hemorrhage and death. The preeclamptic group had more neutropenia, SGA, cesarean section, and less rupture of membranes>18 h. IL-8 was higher in the non-preeclamptic [157.1 pg/mL (86.4-261.3) and 26.54 pg/mL (3.6-87.2) p<0.001]. GRO-α levels were similar in both groups [229.5 pg/mL (116.6-321.3) and 185.5 pg/mL (63.9-306.7) p=0.236]. After multiple regression analysis only absence of preeclampsia was associated with high IL-8 levels. Our data suggest that leukocyte activation may be impaired in infants of preeclamptic mothers.

Magnesium sulfate mitigates acute lung injury in endotoxemia rats

BACKGROUND

Magnesium sulfate (MgSO4) possesses potent anti-inflammation capacity. We sought to elucidate the effects of MgSO4 on mitigating acute lung injury induced by endotoxemia. MgSO4 is an antagonist of the L-type calcium channels and the N-methyl-D-aspartate (NMDA) receptor. The roles of the L-type calcium channels and NMDA receptor in this regard were also elucidated.

METHODS

Ninety-six adult male rats were randomized to receive normal saline, MgSO4 (100 mg/kg), lipopolysaccharide (LPS), LPS plus MgSO4 (10, 50, or 100 mg/kg), LPS plus MgSO4 (100 mg/kg) plus the L-type calcium channel activator BAY-K8644, or LPS plus MgSO4 (100 mg/kg) plus exogenous NMDA (n=12 in each group). Between-group differences in lung injury were evaluated.

RESULTS

Histologic findings, in concert with assays of leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity) and lung water content (wet/dry weight ratio), confirmed that LPS induced acute lung injury. LPS also caused significant inflammatory response (increases in chemokine, cytokine, and prostaglandin E2 concentrations) and imposed significant oxidative stress (increases in nitric oxide and malondialdehyde concentrations) in rat lungs. MgSO4 at the dosages of 50 mg/kg and 100 mg/kg, but not at 10 mg/kg, significantly mitigated the acute lung injury, lung inflammatory response, and oxidative stress caused by endotoxemia. Moreover, the protective effects of MgSO4 were counteracted by BAY-K8644 and exogenous NMDA.

CONCLUSIONS

MgSO4 mitigates lung inflammatory response, oxidative stress, and acute lung injury in endotoxemia rats in a dose-dependent manner. The mechanisms may involve antagonizing the L-type calcium channels and the NMDA receptor.

Magnesium sulfate normalizes placental interleukin-6 secretion in preeclampsia

Interleukin-6 (IL-6) is one of the main proinflammatory mediators of hypertension and endothelial dysfunction in preeclampsia. In this study, we investigated the capacity of the preeclamptic placenta to secrete IL-6 and the effect of magnesium sulfate (MgSO(4)) on it. Placentas from normotensive (37-40 weeks) and preeclamptic (36-40 weeks) pregnancies were dually perfused for 6 h in the absence [normotensive (n = 3); preeclamptic (n = 4)] and presence [normotensive (n = 3); preeclamptic (n = 4)] of MgSO(4). Perfusate samples from the maternal and the fetal circulations were collected at each 30 min throughout the perfusion period and examined for IL-6 by enzyme-linked immunoassay. Statistical analysis was performed using the 2-way analysis of variance. In the absence of MgSO(4), IL-6 levels in the maternal and the fetal circulations of preeclamptic placentas (4.2 ± 1.3 and 0.9 ± 0.5 pg/mL/g cotyledon; respectively) were significantly higher, when compared with normotensive placentas (1.9 ± 0.5 and 0.2 ± 0.2 pg/mL/g cotyledon; respectively) (P < 0.05). Addition of MgSO(4) to the perfusate of normotensive placentas did not affect IL-6 secretion. However, exposure of preeclamptic placentas to MgSO(4) resulted in decreased IL-6 levels in the maternal circulations (1.7 ± 0.3 pg/mL/g cotyledon), when compared with the control group (P < 0.05). In the fetal circulation, the addition of MgSO(4) resulted only in a nonstatistical significant tendency toward decreased IL-6 levels, when compared with the control group. Our findings indicate that the perfused preeclamptic placenta secretes increased levels of IL-6 into the fetal and the maternal circulations and that MgSO(4) may normalize these increased secreted IL-6 levels.

Magnesium sulfate mitigates lung injury induced by bilateral lower limb ischemia-reperfusion in rats

BACKGROUND

Lower limb ischemia-reperfusion (I/R) elicits oxidative stress and causes inflammation in lung tissues that may lead to lung injury. Magnesium sulfate (MgSO(4)) possesses potent anti-oxidation and anti-inflammation capacity. We sought to elucidate whether MgSO(4) could mitigate I/R-induced lung injury. As MgSO(4) is an L-type calcium channel inhibitor, the role of the L-type calcium channels was elucidated.

MATERIALS AND METHODS

Adult male rats were allocated to receive I/R, I/R plus MgSO(4) (10, 50, or 100 mg/kg), or I/R plus MgSO(4) (100 mg/kg) plus the L-type calcium channels activator BAY-K8644 (20 μg/kg) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquets high around each thigh for 3 h followed by reperfusion for 3 h. After euthanization, degrees of lung injury, oxidative stress, and inflammation were determined.

RESULTS

Arterial blood gas and histologic assays, including histopathology, leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity), and lung water content, confirmed that I/R caused significant lung injury. Significant increases in inflammatory molecules (chemokine, cytokine, and prostaglandin E(2) concentrations) and lipid peroxidation (malondialdehyde concentration) confirmed that I/R caused significant inflammation and oxidative stress in rat lungs. MgSO(4), at the dosages of 50 and 100 mg/kg but not 10 mg/kg, attenuated the oxidative stress, inflammation, and lung injury induced by I/R. Moreover, BAY-K8644 reversed the protective effects of MgSO(4).

CONCLUSIONS

MgSO(4) mitigates lung injury induced by bilateral lower limb I/R in rats. The mechanisms may involve inhibiting the L-type calcium channels.

Magnesium sulfate ameliorates maternal and fetal inflammation in a rat model of maternal infection

OBJECTIVE

Magnesium sulfate is proposed to have neuroprotective effects in the offspring. We examined the effects of maternal magnesium sulfate administration on maternal and fetal inflammatory responses in a rat model of maternal infection.

STUDY DESIGN

Pregnant rats were injected with saline, Gram-negative bacterial endotoxin lipopolysaccharide or lipopolysaccharide with magnesium sulfate (pre- and/or after lipopolysaccharide) to mimic infection. Maternal blood, amniotic fluid, fetal blood, and fetal brains were collected 4 hours after lipopolysaccharide and assayed for tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC. In addition, the effect of magnesium sulfate on cytokine production by an astrocytoma cell line was assessed.

RESULTS

Lipopolysaccharide administration induced tumor necrosis factor, interleukin-6, monocyte chemoattractant protein-1, and growth-related oncogene-KC expression in maternal and fetal compartments. Maternal magnesium sulfate treatment significantly attenuated lipopolysaccharide-induced multiple proinflammatory mediator levels in maternal and fetal compartments.

CONCLUSION

Antenatal magnesium sulfate administration significantly ameliorated maternal, fetal, and gestational tissue-associated inflammatory responses in an experimental model of maternal infection.

Peroxisome proliferator-activated receptor {delta} activators induce IL-8 expression in nonstimulated endothelial cells in a transcriptional and posttranscriptional manner

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that are implicated in the regulation of lipid and glucose homeostasis. PPAR agonists have been shown to control inflammatory processes, in part by inhibiting distinct proinflammatory genes (e.g. Il-1β and IFN-γ). IL-8 is a member of the proinflammatory chemokine family that is important for various functions, such as mediating the adhesion of eosinophilic granulocytes onto endothelial cells. The influence of PPARδ activators on the expression of IL-8 in noninduced quiescent endothelial cells is unclear. Therefore, we explored the influence of PPARδ activators on the expression of IL-8 in nonstimulated endothelial cells. PPARδ agonists induce IL-8 expression in human umbilical vein endothelial cells. This induction is demonstrated at the level of both protein and mRNA expression. Transcriptional activation studies using IL-8 reporter gene constructs and DNA binding assays revealed that PPARδ agonists mediated their effects via an NFκB binding site. It is well known that IL-8 is also regulated by mRNA stability. To provide further evidence for this concept, we performed mRNA stability assays and found that PPARδ agonists induce the mRNA stability of IL-8. In addition, we showed that PPARδ agonists induce the phosphorylation of ERK1/2 and p38, which are known to be involved in the increase of mRNA stability. The inhibition of these MAPK signaling pathways resulted in a significant suppression of the induced IL-8 expression and the reduced mRNA stability. Therefore, our data provide the first evidence that PPARδ induces IL-8 expression in nonstimulated endothelial cells via transcriptional as well as posttranscriptional mechanisms.

The immunobiology of aluminium adjuvants: how do they really work?

Aluminium adjuvants potentiate the immune response, thereby ensuring the potency and efficacy of typically sparingly available antigen. Their concomitant critical importance in mass vaccination programmes may have prompted recent intense interest in understanding how they work and their safety. Progress in these areas is stymied, however, by a lack of accessible knowledge pertaining to the bioinorganic chemistry of aluminium adjuvants, and, consequently, the inappropriate application and interpretation of experimental models of their mode of action. The objective herein is, therefore, to identify the many ways that aluminium chemistry contributes to the wide and versatile armoury of its adjuvants, such that future research might be guided towards a fuller understanding of their role in human vaccinations.