E-Selectin Early Overexpression Induced by Allogeneic Activation in Isolated Mouse Lung

Astragalus Polysaccharide Suppresses the Expression of Adhesion Molecules through the Regulation of the p38 MAPK Signaling Pathway in Human Cardiac Microvascular Endothelial Cells after Ischemia-Reperfusion Injury

Astragalus polysaccharide is a major component of radix astragali, a vital qi-reinforcing herb medicine with favorable immune-regulating effects. In a previous animal experiment, we demonstrated that astragalus polysaccharide effectively alleviates ischemia-reperfusion injury (IRI) of cardiac muscle through the regulation of the inflammatory reactions. However, the relationship between this herb and the cohesion molecules on the cell surface remains controversial. In this study, human cardiac microvascular endothelial cells (HCMECs) were used to validate the protective effects of astragalus under an IRI scheme simulated through hypoxia/reoxygenation in vitro. The results indicated that astragalus polysaccharide inhibited the cohesion between HCMECs and polymorphonuclear leukocyte (PMN) during IRI through the downregulation of p38 MAPK signaling and the reduction of cohesive molecule expression in HCMECs.

Differential effector responses by circulating/blood and tissue/peritoneal neutrophils following burn combined with Enterococcus faecalis infection

Recently we found that superimposition of Enterococcus faecalis infection on burn injury caused an eruption of host mortality not seen with either individual challenge. We hypothesized that the Enterococcus bacteria, and/or factors related to these organisms, aggravate burn-induced modulations in host defense by neutrophils. Our study focuses on alterations in neutrophils' oxidative, proteolytic, and adhesive functions and transendothelial migration of neutrophils in burn rats inoculated with E. faecalis. Rats were subjected to burn (30% total body surface area) and then intra-abdominally inoculated with E. faecalis (10(4)CFU kg(-1) b.w). Polymorphonuclear neutrophils (PMNs) were harvested from circulating/blood and tissue/peritoneal cavity at day-2 post injury. Extracellular release of O(-)(2) anion production was determined by luminometry, and intracellular production of reactive oxygen species was measured by digital imaging technique. Fluoroscan analysis and confocal microscopy determined intracellular elastase production. The expression of adhesion molecule CD11b/CD18 was performed by flow cytometry. Calcein AM-labeled PMNs were co-cultured with TNF-α-stimulated rat lung microvascular endothelial cells, and their ability to adhere was assessed by fluorometry and digital imaging and finally, chemotaxis was measured by neutrophil transmigration assays. The results showed differential effector responses by circulatory and/or tissue PMNs. Tissue/peritoneal PMNs produced more O(-)(2), less intracellular elastase, and increased expression of CD11b/CD18 accompanied with increased adhesivity of MIP-2-stimulated PMNs to endothelial cells as compared to circulatory/blood PMNs. This differential effect was more pronounced following burn plus E. faecalis infection, indicating that the combined injury changed neutrophil functions.

Effect of hypomagnesemia on allogeneic activation in mice

INTRODUCTION

Magnesium (Mg) plays an essential role in a wide range of fundamental cellular reactions. It has been reported that in rodents Mg-deficient diet-induced hypomagnesemia results in an early inflammation. We have previously shown that chronic severe hypomagnesemia was associated neither with endothelial cell activation nor with an inflammatory process which are crucial in the allograft rejection process. T cell allogeneic stimulation activates the phosphatase calcineurin which triggers the signaling pathways leading to IL-2 synthesis and lymphocyte proliferation. Full activation of calcineurin requires Mg. Surveys suggest that a significant number of people consume less Mg than the international dietary reference intakes leading to hypomagnesemia in 2.5% to 15% of the general population.

OBJECTIVE

The aim of the study was to investigate the effects of hypomagnesemia on lymphocyte allogeneic activation and proliferation in a murine model of dietary-induced hypomagnesemia.

METHODS

C57BL/6J (H-2(b), Mls(b)) mice were given normal Mg-containing diet (1400 ppm Mg, control mice), or synthetic Mg-deficient diets containing either 50 ppm Mg or 150 ppm Mg for 28 days. Serum Mg levels were determined at days 5, 14 and 28. In parallel, complete urine and faeces were collected by using metabolic cages during a 24 h period for Mg determinations. Splenocytes from C57BL/6 mice fed either normal diet or 50 ppm Mg-diet were used as responder cells in mixed lymphocyte reaction (MLR) performed with splenocytes from C3H/He mice (H-2(k), Mls(IIa)) and C57BL/6 mice fed normal diet as stimulators for allogeneic and isogeneic conditions, respectively. TGF-beta and IL-2 productions were quantified in the supernates of mixed splenocytes cultures. 3x10(6) splenocytes from mice fed 50 ppm Mg-diet were used for calcineurin activity determination at day 28.

RESULTS

In mice fed 150 ppm Mg-diet, moderate hypomagnesemia was observed from day 5 to day 28. Oral supplementation with Mg pidolate (5 or 20 mg Mg/kg/day) could not restore normal serum Mg levels. Serum Mg concentration early decreased in mice fed 50 ppm Mg-diet to achieve stabilized severe hypomagnesemia at days 14 and 28. Urine Mg concentration early dramatically fell down then stabilized in mice fed Mg-deficient diets. In MLR performed at day 28 with splenocytes from mice fed 50 ppm Mg-diet, proliferation and IL-2 production in allogeneic conditions were similar to control mice. No TGF-beta production was detected in any group. Lastly, calcineurin activity measured at day 28 was significantly lower in splenocyes from mice fed 50 ppm Mg-diet than in mice fed control diet.

CONCLUSION

Mg-deficiency does not alter splenocyte allogeneic activation and proliferation and IL-2 production in vitro, although it partially inhibits calcineurin activity. We hypothesize that the remaining activity is sufficient for IL-2 gene normal activation. Alternatively, Mg-deficiency may trigger other signaling pathways leading to IL-2 production.

Pharmacogenomics and end-organ susceptibility to injury in the perioperative period

Genomic medicine has provided new mechanistic understanding for many complex diseases over the last 5-10 years. More recently genomic approaches have been applied to the perioperative paradigm, facilitating identification of patients at high risk for adverse events, as well as those who will respond better/worse to specific pharmacologic therapies. The consistent biological theme emerging is that while inflammation is important in healing from surgical trauma, patients who are too robustly proinflammatory appear to be at higher risk for adverse perioperative events. Precise predictors of each adverse event are being elucidated so that corrective therapeutics can be instituted to improve outcomes in high-risk patients. While the field of perioperative genomics could be considered in its infancy, such approaches are the wave of the future.

Allogeneic activation is attenuated in a model of mouse lung perfused with magnesium-deficient blood

Hypomagnesemia, which is frequently observed in patients treated with calcineurin inhibitors to prevent rejection after allogeneic transplantation, has been associated with a faster rate of decline in allograft function. The effect of hypomagnesemia on lung allograft has not been reported yet. In our model of isolated mouse lung, we have evaluated the early effects of allogeneic lung perfusion with blood from magnesium (Mg)-deficient mice for 3 h on lung activation and remodelling, compared to isogeneic perfusion. Hypomagnesemia (0.21+/-0.07 mmol Mg(2+)/l) was observed in blood from Mg-deficient mice, but no inflammatory pattern. The mRNA level of the intercellular adhesion molecule (ICAM)-1, but neither of the vascular cell adhesion molecule (VCAM)-1, nor of the cytokines tumor necrosis factor (TNF)alpha and interleukin (IL)-2, was enhanced (p<0.05). Although caspase-3 mRNA was transiently enhanced, no apoptotic cells were evidenced in lung tissues even after 3 h. Using cDNA array, we found that the genes encoding RANKL, RANK, TNFR2, NFATX, IL-1R2, IL-6R gp130, SOCS3, PDGFRB, P63, CSF3R, CXCL1, CXCL5, CX3CL1, CSF1, which are involved in inflammation and apoptosis regulation, were markedly up-regulated in allogeneic conditions. Our results support a limited allogeneic activation and an early stage of the inflammatory process in lung, at the time of inflammatory cell recruitment without lung tissue remodelling, as a result of hypomagnesemia. These findings suggest that cyclosporine-related hypomagnesemia, observed in most of the transplanted patients, does not constitute an additional risk for lung allograft outcome.

Immunologic responses to critical injury and sepsis

Almost 2 million patients are admitted to hospitals in the United States each year for treatment of traumatic injuries, and these patients are at increased risk of late infections and complications of systemic inflammation as a result of injury. Host response to injury involves a general activation of multiple systems in defending the organism from hemorrhagic or infectious death. Clinicians have the capability to support the critically injured through their traumatic insult with surgery and improved critical care, but the inflammatory response generated by such injuries creates new challenges in the management of these patients. It has long been known that local tissue injury induces systemic changes in the traumatized patient that are often maladaptive. This article reviews the effects of injury on the function of immune system cells and highlights some of the clinical sequelae of this deranged inflammatory-immune interaction.

Efficacy of mycophenolic acid combined with KRP-203, a novel immunomodulator, in a rat heart transplantation model

BACKGROUND

To explore a more effective and less toxic immunosuppressive strategy in organ transplantation, we recently developed the novel sphingosine-1-phosphate receptor agonist KRP-203. This study examined the efficacy of KRP-203 combined with mycophenolic acid (MPA), an active metabolite of mycophenolate mofetil, in rat heart allografts.

METHODS

Heterotopic heart transplantation was performed in a rat combination of DA (MHC haplotype: RT1(a)) to Lewis (RT1). The recipients were divided into 12 groups (n = 5-7): Syngeneic (Lewis to Lewis), Vehicle, KRP-203 (0.3 and 1 mg/kg), MPA (10 and 20 mg/kg), 10 mg/kg MPA with KRP-203 (0.03, 0.3, 1, and 3 mg/kg), and 20 mg/kg MPA with KRP-203 (0.3 and 1 mg/kg). MPA, KRP-203, and vehicle were given orally.

RESULTS

The mean days of survival were 5.8 (vehicle), 7 and 7.9 (0.3 and 1 mg/kg KRP-203, respectively), 12.7 and >54.4 (10 and 20 mg/kg MPA), >39.6 and >30.5 (10 mg/kg MPA with 1 and 3 mg/kg KRP-203), >100 and >87.8 (20 mg/kg MPA with 0.3 and 1 mg/kg KRP-203). Histologic and immunohistochemical analysis revealed that diffuse mononuclear cell infiltration (macrophages and T cells), hemorrhage, myocardial necrosis and fibrosis, and expression of endothelin-1, transforming growth factor-beta1, monocyte chemoattractant protein-1, interleukin-8, and E-selectin were markedly diminished in the allografts treated with MPA combined with KRP-203. Pharmacokinetic experiments indicated no interaction between MPA and KRP-203, and both combination regimens were well tolerated.

CONCLUSIONS

Combination therapy of MPA with KRP-203 has a therapeutic potential as a novel immunosuppressant strategy in clinical transplantation.