Septic encephalopathy: when cytokines interact with acetylcholine in the brain

Sepsis-associated encephalopathy (SAE) is a brain dysfunction that occurs secondary to infection in the body, characterized by alteration of consciousness, ranging from delirium to coma, seizure or focal neurological signs. SAE involves a number of mechanisms, including neuroinflammation, in which the interaction between cytokines and acetylcholine results in neuronal loss and alterations in cholinergic signaling. Moreover, the interaction also occurs in the periphery, accelerating a type of immunosuppressive state. Although its diagnosis is not specific in biochemistry and imaging tests, it could potentiate severe outcomes, including increased mortality, cognitive decline, progressive immunosuppression, cholinergic anti-inflammatory deficiency, and even metabolic and hydroelectrolyte imbalance. Therefore, the bilateral communication between SAE and the multiple peripheral organs and especially the immune system should be emphasized in sepsis management.

Advances in the management of acute liver failure

Acute liver failure (ALF) is an uncommon but dramatic clinical syndrome characterized by hepatic encephalopathy and a bleeding tendency due to abrupt loss of liver function caused by massive or submassive liver necrosis in a patient with a previously healthy liver. The causes of ALF encompass a wide variety of toxic, viral, metabolic, vascular and autoimmune insults to the liver, and identifying the correct cause can be difficult or even impossible. Many patients with ALF develop a cascade of serious complications involving almost every organ system, and death is mostly due to multi-organ failure, hemorrhage, infection, and intracranial hypertension. Fortunately, the outcome of ALF has been improved in the last 3 decades through the specific treatment for the disease of certain etiology, and the advanced intensive care management. For most severely affected patients who fail to recover after treatment, rapid evaluation for transfer to a transplantation center and consideration for liver transplantation is mandatory so that transplantation can be applied before contraindications develop. This review focuses on the recent advances in the understanding of various contributing etiologies, the administration of etiology-specific treatment to alleviate the liver injury, and the management of complications (e.g., encephalopathy, coagulopathy, cardiovascular instability, respiratory failure, renal failure, sepsis and metabolic disturbance) in patients with ALF. Assessment of the need for liver transplantation is also presented.

The significance and regulatory mechanisms of innate immune cells in the development of sepsis

Sepsis with subsequent multiple organ dysfunction is a pronounced systemic inflammatory response to concealed or known infection and is a leading cause of death in intensive care units. The survival rate of severe sepsis and septic shock has not markedly improved in recent decades despite a great number of receptors and molecules involved in its pathogenesis have been found and taken as therapeutic targets. It is essential to thoroughly understand the host cell-mediated immunity involved in the development of sepsis and sepsis-related organ injury. Recent studies indicate that innate immune cells (such as neutrophils, macrophages, dendritic cells, T lymphocytes, regulatory T cells, and natural killer T cells) play pivotal roles in the maintenance of peripheral homeostasis and regulation of immune responses during sepsis. Therefore, an understanding of the biological significance and pathophysiological roles of different cell populations might gain novel insights into the immunoregulatory mechanisms of sepsis. In this review, we focus on major immune cells that may play potential roles in the contribution of new therapeutic approaches for sepsis.

The tumor necrosis factor-alpha-induced protein 8 family in immune homeostasis and inflammatory cancer diseases

Within the immune system homeostasis is maintained by a myriad of mechanisms that include the regulation of immune cell activation and programmed cell death. The breakdown of immune homeostasis may lead to fatal inflammatory diseases. We set out to identify genes of tumor necrosis factor-alpha-induced protein 8 (TNFAIP8) family that has a functional role in the process of immune homeostasis. Tumor necrosis factor-alpha-induced protein 8 (TNFAIP8), which functions as an oncogenic molecule, is also associated with enhanced cell survival and inhibition of apoptosis. Tumor necrosis factor-alpha-induced protein 8-like 2 (TIPE2) governs immune homeostasis in both the innate and adaptive immune system and prevents hyper-responsiveness by negatively regulating signaling via T cell receptors and Toll-like receptors (TLRs). There also exist two highly homologous but uncharacterized proteins, TIPE1 and TIPE3. This review is an attempt to provide a summary of TNFAIP8 family associated with immune homeostasis and inflammatory cancer diseases.

Effect of high mobility group box-1 protein on immune cells and its regulatory mechanism

High mobility group box-1 protein (HMGB1), which is a nuclear protein, participates in chromatin architecture and transcriptional regulation. When released from cells, HMGB1 also plays a well-established role as a pro-inflammatory mediator during innate immune responses to injury. In the initial stage of injury, there is a release of large quantities of early pro-inflammatory mediators to initiate or perpetuate immune responses against pathogens, but this pro-inflammatory period is transient, and it is followed by a prolonged period of immune suppression. At present, several lines of evidences have suggested that HMGB1 is a late cytokine provoking delayed endotoxin morbidity, which may enhance the production of early proinflammatory mediators, and it can contribute potently to the activation of different immune cells and play a role in the development of host cell-mediated immunity. The biology of HMGB1 has been extensively studied as a pro-inflammatory cytokine of systemic inflammation, however, this review will attempt to provide a summary of the effects of HMGB1 on different immune cells and its regulatory mechanism in acute insults.

Burn injury induces gelsolin expression and cleavage in the brain of mice

Gelsolin is an actin filament-severing and capping protein, affecting cellular motility, adhesiveness and apoptosis. Whether it is expressed in the brain of burned mice has not yet been characterized. Mice were subjected to a 15% total body surface area scald injury. Neuropathology was examined by hematoxylin and eosin staining. Cerebral gelsolin mRNA, distribution and cleavage were demonstrated by quantitative polymerase chain reaction (QPCR), immunohistochemistry and Western blot, respectively. Cysteinyl aspartate-specific protease (caspase)-3-positive cells and activity were also measured. Burn injury could induce pathological alterations in the brain including leukocyte infiltration, necrosis, microabscess and gliosis. Compared with sham-injured mice, gelsolin mRNA was up-regulated at 8h post-burn (pb) in a transient manner in the cortex and striatum of burned mice, while it remained at higher levels in the hippocampus up to 72 hpb. Of interest, gelsolin was further cleaved into 42 and 48 kDa (kilo Dalton) fragments as illustrated in the hippocampus at 24 hpb, and was widely expressed in the brain by activated monocyte/macrophages, astrocytes and damaged neurons. In the meantime, caspase-3-positive cells were noted in the striatum of burned mice and its activity peaked at 24 hpb. To clarify inflammation-induced gelsolin expression and cleavage in the brain, rat pheochromocytoma cells were exposed to lipopolysaccharide to show increased gelsolin expression and caspase-3-dependent cleavage. The results suggest that burn-induced cerebral gelsolin expression would be involved in the activation of both the monocytes and astroglial cells, thereby playing a crucial role in the subsequent inflammation-induced neural apoptosis following burn injury.

The role of regulatory T cells in the pathogenesis of sepsis and its clinical implication

Sepsis is denoted as a complex syndrome that results from a serious infection followed by amplified and dysregulated inflammatory response. The complex immune response associated with sepsis results in a high rate of morbidity and mortality, despite substantial basic science and clinical advances. Recently, accumulating evidence have demonstrated that regulatory T cells (Tregs) play important roles in suppression of immune response, as demonstrated by the number increase and functional enhancement following the onset of severe sepsis or septic shock. This article reviews recent advances in understanding the potential role of Tregs in the pathophysiology of septic response, as well as implications in the development of novel therapeutic strategies for improving the clinical outcome of patients with severe injury and subsequent septic complications.

[Inhibitory effect of lentiviral-mediated RNA on the expression of Foxp3 protein in melanoma cells]

AIM

To explore the feasibility of RNA interference in the treatment of melanoma by inhibiting the Foxp3 gene expression in mouse B16 melanoma cells using RNA interference (RNAi) in vitro.

METHODS

Small interfering RNA (siRNA) was designed according to Foxp3 gene. A short hairpin RNA (shRNA) lentivirus expression vector was constructed and transfected into mouse B16 cells, and RNA interference was induced in vitro. Western blot and real-time RT-PCR were performed to detect the expression of Foxp3 gene. ELISA was applied to detect the changes of TGF-β(1);, TGF-β(2);, IL-10 and other cytokines. The B16 cells after interference were co-cultured with CD4(+);CD25(-);T lymphocytes. CCK8 assay was used to monitor the proliferation of CD4(+);CD25(-);T lymphocytes.

RESULTS

shRNA could suppress the expression level of Foxp3, down-regulate the inhibitory ability of tumor cells on the proliferation of CD4(+);CD25(-);T lymphocytes, and reduce the secretion of TGF-β(1);, TGF-β(2);, IL-10 and other cytokines, in particular the expression of TGF-β(2);.

CONCLUSION

RNA interference can inhibit the expression of target gene Foxp3 in mice melanoma cells and the proliferation of tumor cells. It can also reduce the inhibition on the proliferation of CD4(+);CD25(-);T lymphocytes, and the secretion of inhibitory cytokines.

Treatment with gelsolin reduces brain inflammation and apoptotic signaling in mice following thermal injury

Background

Burn survivors develop long-term cognitive impairment with increased inflammation and apoptosis in the brain. Gelsolin, an actin-binding protein with capping and severing activities, plays a crucial role in the septic response. We investigated if gelsolin infusion could attenuate neural damage in burned mice.

Methods

Mice with 15% total body surface area burns were injected intravenously with bovine serum albumin as placebo (2 mg/kg), or with low (2 mg/kg) or high doses (20 mg/kg) of gelsolin. Samples were harvested at 8, 24, 48 and 72 hours postburn. The immune function of splenic T cells was analyzed. Cerebral pathology was examined by hematoxylin/eosin staining, while activated glial cells and infiltrating leukocytes were detected by immunohistochemistry. Cerebral cytokine mRNAs were further assessed by quantitative real-time PCR, while apoptosis was evaluated by caspase-3. Neural damage was determined using enzyme-linked immunosorbent assay of neuron-specific enolase (NSE) and soluble protein-100 (S-100). Finally, cerebral phospho-ERK expression was measured by western blot.

Results

Gelsolin significantly improved the outcomes of mice following major burns in a dose-dependent manner. The survival rate was improved by high dose gelsolin treatment compared with the placebo group (56.67% vs. 30%). Although there was no significant improvement in outcome in mice receiving low dose gelsolin (30%), survival time was prolonged against the placebo control (43.1 ± 4.5 h vs. 35.5 ± 5.0 h; P < 0.05). Burn-induced T cell suppression was greatly alleviated by high dose gelsolin treatment. Concurrently, cerebral abnormalities were greatly ameliorated as shown by reduced NSE and S-100 content of brain, decreased cytokine mRNA expressions, suppressed microglial activation, and enhanced infiltration of CD11b+ and CD45+ cells into the brain. Furthermore, the elevated caspase-3 activity seen following burn injury was remarkably reduced by high dose gelsolin treatment along with down-regulation of phospho-ERK expression.

Conclusion

Exogenous gelsolin infusion improves survival of mice following major burn injury by partially attenuating inflammation and apoptosis in brain, and by enhancing peripheral T lymphocyte function as well. These data suggest a novel and effective strategy to combat excessive neuroinflammation and to preserve cognition in the setting of major burns.

[Change of serum TGF-beta1 and TNF-alpha in silicosis patients]

OBJECTIVE

To observe serum TGF-beta1 and TNF-alpha in silicosis patients and workers exposed to silica dust to study the role of TGF-beta1 and TNF-alpha in the development of silicosis.

METHODS

One hundred non-exposed workers were selected as control group, 200 workers exposed to silica dust for more than 1 year as exposed group, 32 suspected silicosis patients (originally diagnosed as 0+) as observing group, 130 silicosis patients were as silicosis group. Serum TGF-beta1 and TNF-alpha in each group were determined with ELISA.

RESULTS

Serum TNF-alpha in exposed group [(47.86 +/- 16.52) pg/ml], observing group [(109.11 +/- 31.08) pg/ml], silicosis group [(216.35 +/- 51.03) pg/ml] were significantly higher than that in control group [(6.90 +/- 2.24) pg/ml] (P < 0.01); Silicosis group and observing group were also higher than exposed group (P < 0.01, P < 0.05). Compared with control group [(23.28 +/- 12.24) pg/ml] and exposed group [(29.31 +/- 14.52) pg/ml], serum TGF-beta1 in silicosis group was much higher (P < 0.01).

CONCLUSION

TGF-beta1, and TNF-alpha were essential in the development of silicosis, so the detection of TGF-beta1 and TNF-alpha in peripheral blood was very useful for occupational health surveillance and early diagnosis of silicosis.

[The extracellular role of high mobility group box-1 protein in regulation of immune response]

High mobility group box-1 protein (HMGB1), a highly conserved nuclear DNA-binding protein, is involved in maintenance of nucleosome structure and regulation of gene replication, transcription and translation. Recently, there is accumulating evidence that HMGB1 can be passively or actively released from the nucleus to the extracellular milieu and act as a late proinflammatory cytokine that mediates development of inflammatory diseases, including sepsis. In addition, HMGB1 can also act as an "alarm signal" regulating immune response of host. In this article, we summarized the structure, secretion and receptor signaling pathways of HMGB1. Furthermore, the role and potential mechanism underlying HMGB1 in regulation of immune function were also discussed.

High mobility group box-1 protein regulate immunosuppression of regulatory T cells through toll-like receptor 4

INTRODUCTION

High mobility group box-1 protein (HMGB1), a recently recognized mediator of immune response might contribute to immune suppression when released extracellularly. The present study was performed to clarify effects of HMGB1 on regulatory T cells (Tregs) and the involvement of toll-like receptor (TLR) 4 signaling.

METHODS

CD4(+)CD25(+)Tregs, isolated from spleens of normal mice and treated with HMGB1 in vitro, and those isolated from HMGB1-treated C3H/HeN (wild type) or C3H/HeJ (TLR4 mutant type) mice, were analyzed for expressions of cytotoxic T lymphocyte-associated antigen (CTLA)4, forkhead/winged helix transcription factor p3 (Foxp3) and interleukin (IL)-10 secretion.

RESULTS

HMGB1-treatment was found to markedly decrease the expressions of CTLA4 and Foxp3, as well as IL-10 secretion. Administration of TLR4 neutralizing antibody abolished the phenotypic and functional changes in Tregs induced by HMGB1. Tregs from HMGB1-treated normal mice showed lower expression of CTLA4, Foxp3, and IL-10 secretion when compared with non-treated mice. Yet opposite results were observed in that of C3H/HeJ mice. Moreover, HMGB1 stimulation could down-regulate the expression of TLR4 on Tregs.

CONCLUSION

Our data suggest that HMGB1 has the ability to directly modulate the suppressive capacity of CD4(+)CD25(+)Tregs, and TLR4 might be a potential receptor essential for the negative effect of HMGB1 on CD4(+)CD25(+)Tregs activity.

Association between high-mobility group box-1 protein release and immune function of dendritic cells in thermal injury

The present study was performed to investigate in vivo the effect of high-mobility group box-1 protein (HMGB1) on the maturation of dendritic cell (DC) and the influence on T-cell-mediated immunity after thermal injury. Rats were randomly divided into 3 groups as follows: sham burn group, burn group, and burn with ethyl pyruvate (EP) treatment group, and they were sacrificed on post burn days (PBD) 1, 3, 5, and 7 respectively. MACS microbeads were used to isolate splenic DCs and column of nylon wool to obtain T cells. Phenotypes were analyzed by flow cytometry and cytokines were determined with ELISA kits. The expression levels of splenic HMGB1 were significantly elevated during PBD 1-7. DC expressed similar CD80 levels, strongly enhanced CD86, and slightly elevated MHC class II levels in comparison to DC from sham-injured rats, and protein levels of IL-12 were not increased after thermal injury. Administration of EP to inhibit HMGB1 could significantly enhance expression levels of CD80, MHC class II on DC surface, and IL-12 production after burns. Simultaneously, proliferative activity and expression levels of IL-2 as well as IL-2R alpha of T cell were restored. These results suggested that the excessively released HMGB1 might stimulate splenic DC to mature abnormally and down-regulate the IL-12 production, and further shifting of Th1 to Th2 with suppression of T-lymphocyte immune function following burn injury.

[The central mechanism for estrogen receptor to mediate nutrients and energy metabolism]

Estrogen is demonstrated to be involved in the development and progress of diabetes mellitus. Recently studies have indicated that estrogen receptor (ER) play a crucial role in the modulation of nutrients and energy metabolism. Estrogen could regulate the expressions of anorexia and hyperphagic neuropeptide in the hypothalamus by genomic actions via nuclear ER, or via membrane ER linking to the phosphatidylinositol 3-kinase (PI3-K)/Akt and ERK1/2 mitogen-activated protein kinase (MAPK) pathways. The mice with hypothalamic ERalpha silencing exhibited the features of typical metabolic syndrome, suggesting the role of ERalpha in peripheral nutrient metabolism. Further studies showed that the central ERalpha interacts with both insulin and leptin signaling pathways. The elucidation of the mechanism of central ER in energy balance and nutrient metabolism would provide the novel strategy to overcome the abnormality of glucose metabolism and energy imbalance induced by estrogen disorder in clinical settings.

[Advances in mitochondrial fusion-fission and Ca2+ signaling in mammals]

Mitochondria are dynamic organelles and maintain their structure through two opposing processes of fusion and fission. In mammals, there are many factors which influence the equilibrium between mitochondrial fusion and fission. It has been known that mitochondrial fusion is controlled by mitochondria-shaping proteins, including the large GTPase mitofusins (Mfn1/2) and optic atrophy protein 1 (OPA1), whereas the protein Fis1 and dynamin-related protein 1 (Drp1) are the key mediators of mitochondrial fission. Recent data revealed the relationship between mitochondrial fusion/fission and Ca2+ signaling. Ca2+ handling is controlled by the change of mitochondrial fission-fusion balance. On the other hand, intra- and near-mitochondrial Ca2+ signals can modify mitochondrial morphology and cellular distribution.

Association between regulatory T cell activity and sepsis and outcome of severely burned patients: a prospective, observational study

Introduction

To investigate the significance of changes in regulatory T cells (Tregs) activity and its relationship with sepsis, as well as outcome of patients with major burns.

Methods

The periphery blood samples of 106 patients were collected on post-burn days 1, 3, 7, 14, and 21. Tregs were isolated and their phenotypes (cytotoxic T-lymphocyte-associated antigen 4 and forkhead/winged helix transcription factor p3) were analyzed by flow cytometry, and the contents of cytokines (interleukin-10 and transforming growth factor-β1) released into supernatants by Tregs were also determined by enzyme-linked immunosorbent assay kits. Gene expressions of cytokines were assessed by real-time quantitative polymerase chain reaction.

Results

Expressions of Tregs phenotypes and gene/protein expression of cytokines were all elevated after burn, and there were obvious differences among patients with various burn sizes. They were also higher in septic patients than those without sepsis. Among septic patients, the expressions of Tregs phenotypes and the levels of cytokines were markedly lower in the survival group than those in patients with fatal outcome.

Conclusions

Severe burn injury per se could lead to the changes in Tregs activities. Elevated levels of cytokines produced by Tregs and activation markers on Tregs surface might play an important role in the pathogenesis of sepsis and mortality in burned patients.

[Effect of "Xuebijing injection" on expression of high mobility group box-1 protein and acute liver injury in rats with scald injury]

OBJECTIVE

To investigate the effect of "Xuebijing injection" (Xuebijing in brief) on expression of hepatic high mobility group box-1 protein (HMGB1) and acute liver injury in rats with scald injury.

METHODS

Seventy-eight rats were divided into sham scald group (n = 18), scald group (n = 30), and Xuebijing treatment group (n = 30). Rats in the latter 2 groups were subjected to 30% full-thickness scald injury followed with delayed resuscitation. These rats were sacrificed at 8th, 24th, and 72nd post-injury hour (PIH) to collect specimens. The hepatic pathological changes were observed. Serum levels of ALT and AST were detected. HMGB1 mRNA level in hepatic tissue was detected by the reverse transcription polymerase chain reaction. Protein relative expression quantity of HMGB1 in hepatic tissue was determined with Western blot and immunohistochemistry. Outcomes were denoted in integral absorbance ratio and absorbance value respectively.

RESULTS

Massive infiltration of inflammatory cells in hepatic tissues was observed in scald group under light microscope, especially at 24th PIH, and it was decreased in quantity in Xuebijing treatment group. Compared with those of sham scald group, both mRNA and protein expressions of HMGB1 in hepatic tissue of scald group were significantly enhanced during 8-72 PIH (P < 0.05 or P < 0.01), along with markedly increased serum levels of ALT and AST (P < 0.05 or P < 0.01). Compared with those in scald group at 24h and 72nd PIH, hepatic HMGB1 mRNA expressions (0.75 +/- 0.12 vs. 0.60 +/- 0.15 and 0.78 +/- 0.11 vs. 0.55 +/- 0.07, respectively) and protein values (200 +/- 13 vs. 163 +/- 13 and 175 +/- 14 vs. 160 +/- 16, respectively) in Xuebijing treatment group were markedly down-regulated (P < 0.05 or P < 0.01), and serum levels of ALT and AST decreased in different degrees (P < 0.05 or P < 0.01).

CONCLUSIONS

HMGB1, the delay-appearing inflammatory mediator, is involved in the pathogenesis of inflammatory response in hepatic tissue in severely scalded rats. Treatment with Xuebijing can markedly down-regulate hepatic HMGB1 expression and protect liver against acute injury induced by delayed resuscitation.

[The enhancing effect of "Xuebijing injection" on lipopolysaccharide-induced apoptosis of regulatory T cells and mediation of polarization of helper T cells]

OBJECTIVE

To investigate the enhancing effect of Chinese medicine-Xuebijing injection on lipopolysaccharide (LPS) -induced apoptosis of CD4+ CD25+ regulatory T cells (Tregs) and polarization of helper T cells (Th).

METHODS

CD4+ CD25+ Tregs collected from rat spleen in vitro by immunomagnetic beads assay were divided into the control group, anti-CD3/CD28 group, anti-CD3/CD28 + LPS group, anti-CD3/CD28 + "Xuebijing injection" group and anti-CD3/CD28 + LPS + "Xuebijing injection" group. Tregs apoptosis rate and expression of winged helix transcription factor (Foxp3) in Tregs were detected by flow cytometry on 3rd post culture day. CD4+ CD25- T cells were co-cultured with CD4+ CD25- Tregs (1:1) for 68 hours with canavalin A stimulation. Interferon gamma (gamma-IFN), interleukin (IL)-4 and IL-17 in supernatants, which respectively was secreted by Th1, Th2 and Th17, were measured by ELISA.

RESULTS

Tregs apoptosis rate of anti-CD3/CD28 + LPS + "Xuebijing injection" group (45.1 +/- 2.7%) was significantly higher than that of anti-CD3/CD28 + LPS group (29.4 +/- 1.6%, P < 0.01). Meanwhile, Foxp3 expressions in Tregs in above 2 groups were 95 +/- 9 and 140 +/- 18 respectively, showing statistically significant difference between them (P < 0.01). Gamma-IFN levels secreted in anti-CD3/CD28 + LPS + "Xuebijing injection" group were significantly higher than those in anti-CD3/CD28 + LPS group (P < 0.01), while IL-4 levels had an opposite tendency compared with gamma-IFN (P < 0.05), resulting in a marked increase in the ra- tio of gamma-IFN/IL-4 in anti-CD3/CD28 + LPS + "Xuebijing injection" group (P < 0.01). In anti-CD3/ CD28 + "Xuebijing injection" group, IL-17 secretion levels were significantly decreased compared with anti-CD3/CD28 group (P < 0.05).

CONCLUSIONS

Activation of CD4+ CD25+ Tregs induced by LPS may mediate Th1 shift to Th2 response. "Xuebijing injection" can effectively regulate immune function of T cells, increase the LPS-induced apoptosis of CD4+ CD25+ Tregs as well as enhance the polarization of Th2 to Th1, thereby abating the suppressive state of cell-mediated immunity.

[Distribution and clinical significance of CD14 promoter-159C/T polymorphism in patients with extensive burn]

OBJECTIVE

To investigate association of CD14-159C/T polymorphism with expression of leukocyte CD14 mRNA and plasma soluble CD14 (sCDI4) level in severe burn patients.

METHODS

Seventy-seven patients with total burn surface area equal to or over 30% TBSA were hospitalized in the First Hospital Affiliated to the PLA General Hospital and Beijing You'anmen Hospital from June 2004 to June 2006. Blood samples were collected on 1st, 3rd, 5th, 7th, 14th, 21st, and 28th postburn day (PBD) for determination of CD14-159C/T polymorphism by PCR-subsequent restriction fragment length polymorphism (RFLP) analysis,plasma level of sCD14 and leukocyte CD14 mRNA expression were measured by ELISA and RT-PCR.

RESULTS

Frequency of the T and C allele was 59.1%, 40.9%, respectively. Seven cases (9.1%) were homozygote (CC genotype), 49 cases (63.6%) were heterozygote (TC genotype), and 2 cases (27.3%) were TT homozygous allele,which reached the Hard-Weinberg equilibrium. Three cases with CC homozygote, 38 cases with TC heterozygote, and 15 cases with TT homozygous allele were complicated with sepsis, ending in MODS in 1, 19, 10 cases, respectively. Expression of leukocyte CD14 mRNA +/- 35, re- spectively), which were markedly higher than that in patients with CC homozygote during 7th-21st PBD (P < 0.05 or 0.01). The plasma level of sCD14 in patients with CC homozygote was significantly lower than that in patients with TC heterozygote on 5 PBD (85 +/- 46 microg/L vs 134 +/-43 mmicrog/L, P < 0.01), which were higher in patients with TC heterozygote and TT homozygous allele than that in patients with CC homozygote on 21st, 28thh PBD (P < 0.01). Conclusions In CD14 gene promoter-159C/T polymorphism, the gene and protein expression of CD14 in patients with TT, TC genotype are much higher than those in patients with CC homozygote. CD14 gene promoter-159 C/T polymorphism with TT homozygote may be one of the major markers in extensive burn patients in whom infection may progress to MODS. Compared with other genetypes, the incidence of MODS in sepsis patients with TT genotype increase markedly.

[Research advances in Th17 cells]

CD4+ T cells have been divided into different subsets, essentially based on the cytokines they produce. These subsets include T helper cell (Th)1, Th2 and regulatory T cells (Treg). Recently, another subpopulation of T cells has been identified, and it was named as Th17, which is characterized by the release of interleukin (IL)-17. The discovery of Th17 cells is not only a challenge to some traditional theories, such as the differentiation of CD4+ T cells and the drift theory of Th1/Th2, but also provides new research approach to inflammatory and immunologic diseases, especially, the balance among Th1, Th2, Treg and Th17 cells may play an important role in maintaining the normal immune response.

[Effect of high mobility group B1 protein on the function of phagocytosis and the expression of I-A/-E of peritoneal macrophages in mice]

AIM

To investigate the effect of extracellular high mobility group B1 protein (HMGB1) on the immunological function of macrophages.

METHODS

Peritoneal macrophages from mice were stimulated by concentration gradient HMGB1 in vitro. Male BALB/c mice were divided randomly into control group (normal saline, i.p.), low or high dose group (treated with HMGB1 0.2 microg or 20 microg per mouse, respectively, i.p.). Phagocytosis of neutral red and I-A/-E expression of macrophages was assayed.

RESULTS

(1) HMGB1 regulated the phagocytosis of macrophages in a time- and dose-dependent manner, but it did not regulate the expression of I-A/-E in vitro. Moreover, the phagocytosis of macrophages was significantly enhanced by stimulating of HMGB1 at a concentration of 10 microg/L as compared with other stimulating concentrations at culture-hour 6 and 12 (P<0.05 or P<0.01). (2) The capacity for phagocytosis of macrophages was reduced from 43% to 67% when the mice were challenged with HMGB1 in vivo. However, as compared with animals in control group, neutral red phagocytosis of macrophages was depressed markedly in the animals inflicted with high dose HMGB1 for 24 hours (P<0.05). The I-A/-E expression of macrophages was up-regulated markedly in the animals inflicted with low dose HMGB1 for 48 hours as compared to animals treated with normal saline and high dose HMGB1(P<0.05 or P<0.01).

CONCLUSION

High dose HMGB1 can depress the phagocytosis of macrophages, and low dose HMGB1 can enhance macrophage-mediated immunity. Moderate HMGB1 loading is beneficial to immune defense.

[Change in T cell-mediated immunity and its relationship with high mobility group box-1 protein levels in extensively burned patients]

OBJECTIVE

To investigate the change in T cell-mediated immunity and its relationship with plasma high mobility group box-1 protein (HMGB1) levels in severely burned patients.

METHODS

Thirty-five extensively burned patients (> 30% total body surface area) were included in this study, and were divided into MODS group (n = 13) and non-MODS group (n = 22). The blood samples were collected on post burn days 1, 3, 5, 7, 14, 21 and 28. The plasma levels of HMGB1 were measured by using ELISA, and T lymphocyte proliferation response and its IL-2 production ability in peripheral blood were determined too. In addition, the ratio of CD4+/CD8+ T cells were detected by using flow cytometry.

RESULTS

Plasma HMGB1 levels were markedly elevated on post burn day 1 in severely burned patients, and HMGB1 level was significantly higher in MODS group than in non-MODS group (P < 0.05). Lymph proliferation response and IL-2 production of T cells in peripheral blood, and the ratio of CD4+/CD8+ T cells in MODS group were markedly lower than those in non-MODS group on post burn days 1, 14, 21 and 28 (all P < 0.05). It indicated that plasma HMGB1 levels were negatively correlated to T cellular immune function parameters, including lymphocyte proliferation response, IL-2 production, and the ratio of CD4+/ CD8+ T cells in extensively burned patients (all P < 0.05).

CONCLUSIONS

Extensive burns could lead to T cellular immune dysfunction, which appears to be associated with the development of MODS. HMGB1, as an important late mediators of inflammation, might be involved in the pathogenesis of suppression of T cell-mediated immunity in these patients.

[Influence of high mobility group box-1 protein on the correlation between regulatory T cells and CD4+ CD25- T cells of spleen in mice]

OBJECTIVE

To investigate the influence of high mobility group box-1 protein (HMGB1) on the immunosuppression function of splenic regulatory T cells (Tregs) and its potential regulatory mechanism underlying the effect on CD4+ CD25- T cells in mice.

METHODS

CD4+ CD25+ Tregs isolated from the spleens of male BALB/c mice by magnetic beads were seeded on 96-well (1 x 10(5) cells/well) cell culture plates coated with 1 microg/ml anti-CD3 and soluble CD28. After being stimulated with HMGB1 for different time and concentrations, the secretions of IL-2 and IL-10 were analyzed by ELISA. Tregs stimulated for 72 hours were cultured with CD4+ CD25- T cells together. The suppressive activity of CD4+ CD25+ Treg to CD4+ CD25- T cells was analyzed by MTT test. IL-2, IL-10, IL-4, and interferon (IFN)-gamma in the cell suspensions were determined by ELISA.

RESULTS

After stimulation with HMGB1, the suppressive activity of splenic Tregs in mice were significantly down-regulated at 72 hours, when the proportion of Tregs to CD4+ CD25- T cells was 1 : 1. The secretion of IL-2 of Tregs stimulated by HMGB1 was not markedly changed (P > 0.05), while a dose-dependent decrease between IL-10 induction and HMGB1 concentration was obviously (P < 0.05). When CD4+ CD25- T cells were cultured with stimulated Tregs, comparing with unstimulated-Treg group, levels of IL-2 and IFN-gamma were elevated following the increased concentration of HMGB1 (P < 0.05 or P < 0.01). Meanwhile the secretion of IL-4 and IL-10 significantly decreased when cultured with stimulated Tregs (P < 0.05).

CONCLUSIONS

These data suggested that HMGB1 stimulation can result in significant down-regulation of immunosuppression of splenic Tregs in mice. HMGB1 might be a potential immunoregulatory signal that influences the proliferation of effector T cells, secretion of IL-2 and cells-polarization by inhibiting CD4+ CD25+ Tregs activity.

[The receptor mechanism of high mobility group box-1 protein induced apoptosis in peritoneal macrophages in mice]

OBJECTIVE

To investigate the influence of high mobility group box-1 protein (HMGB1) on apoptosis of peritoneal macrophages in mice and its receptor mechanism.

METHODS

The peritoneal macrophages were isolated from female BALB/c mice and divided into 4 groups according to different stimuli: i. e, HMGB1 group (with treatment of 10 microg/ml HMGB1 for 24 hours), HMGB1 and anti-receptor advanced glycation end products (RAGE) antibody group (with treatment of 5 microg/ml anti-RAGE antibody for 2 hours followed by HMGB1 stimulation), Recombinant mouse RAGE/Fc chimera (rmRAGE/Fc) and HMGB1 group (10 microg/ml of rmRAGE/Fc and 10 microg/ml HMGB1 were pre-mixed for 2 hours, then the peritoneal macrophages were treated with the mixture), control group (with treatment of phosphate buffer). Expression of RAGE on the surface of macrophages, and the apoptotic rate of the cells were determined by flow cytometry. Laser scanning confocal microscopy was used to observe the apoptosis of the cells.

RESULTS

The percentage of macrophages with positive RAGE expression in HMGB1 group [(54 +/- 12%)] was markedly increased compared to the controls [(13 +/- 5)%, P < 0.01], and fluorescence density of RAGE expression was also significantly different between two groups (126 +/- 10 vs 34 +/- 8, P < 0.01). The occurrence of apoptosis in HMGB1 and rmRAGE/Fc group, as well as in HMGB1 plus anti-RAGE group were much higher than that in control group, and the number of macrophages with apoptosis and necrosis at late stage was obviously increased in HMGB1 group. The apoptic rate in HMGB1 group was (39.5 +/- 2.3)%, which was significantly higher than those in HMGB1 and rmRAGE/Fc group (17.3 +/- 3.6)%, and HMGB1 and anti RAGE group (14.8 +/- 4.8)%, (P < 0.01), which were significantly higher than those in control groups (5.4 +/- 2.3)%, (P < 0.01).

CONCLUSION

RAGE is one of the major receptor to induce apoptosis of macrophages, and the up-regulation of its expression is induced by HMGB1.

Role of Janus kinase/signal transducer and activator of transcription pathway in regulation of expression and inflammation-promoting activity of high mobility group box protein 1 in rat peritoneal macrophages

Signal transduction mechanism in the regulation of high mobility group box protein 1 (HMGB1) has not yet been well elucidated. Our data showed for the first time that Janus kinase-signal transduction and activator of transcription (JAK/STAT) pathway played a major role in the regulation of expression and inflammatory effect of HMGB1. The study was carried out in the following sequence. Firstly, the role of JAK/STAT pathway in the regulation of expression of HMGB1 was examined. After stimulation with 75 ng/mL LPS in vitro, significant increases in HMGB1 expression and prompt activation of JAK/STAT pathway were demonstrated in cultured macrophages. On the other hand, administration of AG490 (specific inhibitor for JAK2), fludarabine (specific inhibitor for STAT1) or rapamycin (specific inhibitor for STAT3) markedly suppressed HMGB1 expression. Secondly, the role of JAK/STAT pathway in the regulation of TNF-alpha expression induced by HMGB1 was examined. When macrophages were stimulated with 10 microg/mL HMGB1 in vitro, significant increases in TNF-alpha expression and prompt activation of JAK/STAT pathway were demonstrated, whereas inhibitors of JAK/STAT pathway significantly suppressed TNF-alpha expression. Taken together, our data strongly indicated that expression and inflammatory effect of HMGB1 could be mediated by JAK/STAT pathway and suggested a possible clinical strategy to control an inflammatory effect of HMGB1 in sepsis.

Sodium butyrate prevents lethality of severe sepsis in rats

This study was performed to investigate a novel strategy to pharmacologically inhibit high-mobility group box 1 protein (HMGB1) expression with sodium butyrate, a short-chain fatty acid. Using a sepsis model induced by cecal ligation and puncture (CLP), 100 male Wistar rats were randomly divided into 4 groups as follows: control group (10 rats), sham operation group (10 rats), CLP group (further randomized into 2, 6, 12, 24, 48, and 72 h post-CLP subgroups, each 10 rats), and sodium butyrate treatment group (further randomized into 12 and 24 h post-CLP subgroups, each 10 rats). Animals of all groups were killed at designated time points, and blood and tissue samples from livers, lungs, kidneys, and small intestines were harvested to determine organ damage-related variables, and HMGB1 mRNA expression was assessed by the reverse-transcription-polymerase chain reaction. In addition, we observed the effect of treatment with sodium butyrate on survival rate in septic rats. The results showed that early treatment with sodium butyrate can markedly reduce serum alanine aminotransferase, creatinine levels at 12 h, and pulmonary myeloperoxidase activity at 24 h post-CLP, and significantly improve the 1- to 6-day survival rates in animals subjected to CLP (P < 0.05-0.01). These findings suggest that HMGB1 is excessively expressed and produced in sepsis. Sodium butyrate can markedly inhibit HMGB1 mRNA expression and may have protective effect on multiple organ damage in sepsis.

[The clinical significance of changes in immunological function of T lymphocyte in severe burn patients with sepsis]

OBJECTIVE

To observe the immunological function changes in T lymphocyte in severe burn patients with sepsis, and to explore its relationship with sepsis.

METHODS

Fifty-nine burn patients with burn surface exceeding 30% TBSA were enrolled in the study, and they were divided into sepsis group (S, n =43) and non-sepsis group (NS, n = 16). The peripheral venous blood samples of the patients in both groups were collected on 1, 3, 5, 7, 14, 21 and 28 post-burn days (PBD). The T lymphocyte proliferation ability and the interleukin-2 (IL-2) level in both groups were observed and the correlation between them were analyzed. The percentage of CD3+/CD4+ T lymphocytes and its apoptosis rate were determined by flow cytometry and the correlation between them was analyzed.

RESULTS

Compared with that in NS group, the proliferation ability of T lymphocyte and the level of IL-2 were significantly decreased in patients in S group on 1, 14, 21, and 28 PBD (P < 0.05 or P < 0.01). The inhibition of T lymphocyte proliferation was positively correlated to the low level of IL-2 production in burn patients (r = 0.82, P < 0.01). The percentage of CD3+/CD4+ T lymphocytes in S group were obviously lower than that in NS group on 1, 5, 14, 21, 28 PBD, whereas on opposite tendency in the apoptosis rate of CD3+ CD4+ T lymphocytes were found at the same time (P < 0.05 or P < 0.01). The percentage of CD3+/CD4+ T lymphocytes was negatively correlated to apoptosis rate of T lymphocytes (r = -0.66, P < 0.05).

CONCLUSION

The immunological function of T lymphocyte in severely burn patients with sepsis is depressed persistently. Apoptosis of T lymphocyte may participate in the pathological process of cell immunological disorder induced by sepsis.

[Immunoregulatory effect of dendritic cells and its signal transduction]

Dendritic cells (DCs) are highly efficient antigen-presenting cells (APC). Following antigen stimulating, DC could migrate from peripheral tissues to lymphoid organs via chemotactic factors and up-regulate major histocompatibility complex, costimulatory molecules, adhesion molecules, secreting cytokines, acquiring the unique capacity to prime naive T cells. DC takes up antigen through phagocytosis, pinocytosis, and endocytosis via different groups of receptor families, such as C-type lectin receptors (CLRs) for antigen capture and presentation, Toll-like receptors (TLRs) for pathogen recognition and DC activation. The present review focuses on the progress of DC biology as well as immunoregulation, activation via distinct pathogen recognition receptors and intracellular signal transduction pathway.

Sensitive and selective liquid chromatography-mass spectrometry method for the quantification of rosiglitazone in human plasma

A sensitive and selective high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS-MS) method for determination of rosiglitazone in human plasma has been developed. After the addition of the internal standard, plasma samples were precipitated by acetonitrile. The compounds were separated on a proC18 column using a mixture of ammonium acetate buffer (0.02 M, pH 6.5) and acetonitrile (in the ratio of 47:53, v/v) as mobile phase. A Finnigan LCQdeca plus ion trap mass spectrometer connected to a Finnigan Surveyor HPLC was used to develop and validate the method. Linearity was established for the range of concentrations 1-1000 ng/ml with a coefficient of determination (r(2)) of 0.999. The intra-day accuracy for rosiglitazone ranged from 110.0 to 99.2% at low, medium and high levels. The inter-day accuracy was less than 15%. The lower limit of quantitation (LLOQ) was identified reproducible at 1.0 ng/ml with a precision of 5.7%. After validation, the method was used to study the pharmacokinetic profile of rosiglitazone in five healthy volunteers after administration of a single oral dose (4.0mg). The proposed method enabled the unambiguous evaluation and quantitation of rosiglitazone for pharmacokinetic, bioavailability or drug-drug interaction studies. A possible chromatography peak (m/z 121, its parent ion m/z 344) of N-demethyl rosiglitazone was observed at 3.49 min during determining rosiglitazone. This may be also a potential method for simultaneous determination of rosiglitazone and its metabolite N-demethyl rosiglitazone concentrations in plasma.

[The influence of CD14 genomic polymorphism on CD14 gene expression as well as protein release and its clinical significance in patients with extensive burns]

OBJECTIVE

To investigate the influence of a lipopolysaccharide receptor CD14-159C/T genomic polymorphism on CD14 gene expression as well as protein release, and the relation of sepsis susceptibility and prognosis in patients with extensive burns.

METHODS

The study group consisted of 26 patients with burns covering more than 30% of the total body surface area. The CD14 gene polymorphism was determined by polymerase chain reaction (PCR) and subsequent HaeIII restriction enzyme digestion of the PCR products. Meanwhile, the association of CD14, TNF-alpha mRNA expression in leukocytes and soluble CD14 (sCD14) levels in serum with CD14-159 polymorphism as well as prognosis after burns was also studied.

RESULTS

The T allele frequencies in sepsis patients and non-survivors were higher than those in non-septic patients and survivors. The levels of CD14 mRNA, TNF-alpha mRNA expression and serum sCD14 were significantly different among patient groups with TT, TC, and CC genotypes. The above differences were also existed between survivors and non-survivors. CD14 mRNA expression was higher in heterozygotes (TT and TC) than in C homozygous patients (P < 0.05 or P < 0.01), and sCD14 level was higher in heterozygotes (TC) than C homozygous patients on day 7 postburn (P < 0.05). During the 28-day observation period, mean TNF-alpha mRNA expression was higher in patients homozygous for T allele than C homozygotes (P < 0.05). In addition, higher CD14 mRNA values were found in non-survivors compared to those in survivors on days 7 and 28 postburn (P < 0.05).

CONCLUSIONS

CD14C-159T polymorphism might markedly influence CD14 mRNA expression and sCD14 levels, and it seems to be associated with sepsis susceptibility and prognosis in patients with extensive burns. The T allele could be a genetic risk marker of adverse prognosis.

[High mobility group box-1 protein activates Janus kinase-signal transducer and activator of transcription pathway in rat peritoneal macrophages]

OBJECTIVE

To investigate the potential signal transduction mechanism in high mobility group box-1 protein (HMGB1)-induced inflammatory response in rat peritoneal macrophages.

METHODS

Peritoneal macrophages obtained from male Wistar rats were incubated for 3 days before they were stimulated by HMGB1 (10 microg/ml). At various time points after HMGB1 stimulation, macrophages were denatured directly in cell culture flasks to detect activation of Janus kinase-2 (JAK2), signal transducer and activator of transcription-1 (STAT1) and STAT3 by immunoprecipitation, Western blotting and electrophoretic mobility shift assay, respectively.

RESULTS

HMGB1 stimulation could activate STAT1 and STAT3 in peritoneal macrophages in 2 hours, among them the activation of STAT3 appeared to be the quickest, peaking as early as 10 minutes after stimulation. But no marked change in JAK2 activity was observed within 2 hours following HMGB1 stimulation.

CONCLUSION

These data suggest that Janus kinase-signal transducer and activator of transcription pathway might be involved in regulation of HMGB1-induced inflammatory response in peritoneal macrophages.

Tissue lipopolysaccharide-binding protein expression in rats after thermal injury: potential role of TNF-alpha

Recent studies have suggested that levels of lipopolysaccharide-binding protein (LBP) might play a harmful role by up-regulating the host's sensitivity to endotoxin. Our previous studies demonstrated that local endotoxin could up-regulate LBP expression after acute insults, however, the definite molecular mechanisms downstream of endotoxin action remain unclear. This study investigates whether tumor necrosis factor (TNF-alpha) might be responsible for the LBP formation during endogenous endotoxemia postburn. Wistar rats were anesthetized, and a 35% TBSA full-thickness burn was created. Animals were randomly divided into normal control, thermal injury and anti-TNF-alpha mAb treatment group. A significant elevation of plasma endotoxin concentration was observed after acute insults. TNF-alpha levels in plasma also rapidly increased after thermal injury. Meanwhile, LBP mRNA expression markedly increased in liver, lungs, kidneys and intestine postburn. There was no detectable TNF-alpha in the plasma of anti-TNF-alpha mAb treated animals. Treatment with anti-TNF-alpha mAb also resulted in significantly lower concentrations of LBP mRNA in local tissues. Additionally, several organ function parameter levels in plasma significantly decreased in treatment group. These results demonstrated that an increase of plasma TNF-alpha levels caused by burns might be associated with a marked elevation of tissue LBP mRNA expression, which could contribute to the development of multiple organ damage.

Risk factors of development of gut-derived bacterial translocation in thermally injured rats

AIM: Studies have demonstrated that gut-derived bacterial translocation (BT) might play a role in the occurrence of sepsis and multiple organ dysfunction syndrome (MODS). Yet, no convincing overall analysis of risk factors for BT has been reported. The purpose of this study was to evaluate the related factors for the development of BT in burned rats.

METHODS: Wistar rats were subjected to 30% third-degree burns. Then samples were taken on postburn d 1, 3, and 5. Incidence of BT and counts of mucosal bifidobacteria, fungi and E. coli, mucus sIgA, degree of injury to ileal mucosa, and plasma interleukin-6 were observed. Univariate analysis and multivariate logistic regression analysis were performed.

RESULTS: The overall BT rate was 53.9% (69 in 128). The result of univariate analysis showed that the levels of plasma endotoxin and interleukin-6, the counts of mucosal fungi and E. coli, and the scores of ileum lesion were markedly increased in animals with BT compared with those without (P = 0.000-0.005), while the levels of mucus sIgA and the counts of mucosal bifidobacteria were significantly reduced in animals with translocation compared with those without (P = 0.000). There was a significant positive correlation between mucus sIgA and the counts of mucosal bifidobacteria (r = 0.74, P = 0.001). Moreover, there were strong negative correlations between scores of ileum-lesion and counts of bifidobacteria (r = -0.67, P = 0.001). Multivariate logistic regression revealed that ileum lesion score (odds ratio [OR] 45.52, 95% confidence interval [CI] 5.25-394.80), and counts of mucosal bifidobacteria (OR 0.039, 95% CI 0.0032-0.48) were independent predictors of BT secondary to severe burns.

CONCLUSION: Ileal lesion score and counts of mucosal bifidobacteria can be chosen as independent prognosis factors of the development of BT. Specific interventions targeting these high-risk factors might be implemented to attenuate BT, including strategies for repair of damaged intestinal mucosae and restoration of the balance of gastrointestinal flora.

[Dynamic change in interleukin-18 and its relationships with multiple organ dysfunction syndrome]

OBJECTIVE

To determine interleukin-18 (IL-18) in plasma after trauma, and evaluate its relationship with multiple organ dysfunction syndromes.

METHODS

A total of 54 patients were enrolled and divided into low injury seriousness score (L-ISS) and high injury seriousness score (H-ISS) groups. Blood IL-18 levels were determined on admission, day 4, day 7 and day 14 after trauma using enzyme-linked immunoadsorbent assay (ELISA), and the relationship between its level and organ dysfunction was analyzed.

RESULTS

Plasma IL-18 concentration was significantly increased on posttrauma day 4 and day 7. Also, plasma IL-18 concentration was significantly higher in patients with organ dysfunction.

CONCLUSION

This study suggests that major trauma can lead to a marked elevation of IL-18, which might be associated with organ dysfunction.

The potential role of Staphylococcal enterotoxin B in rats with postburn Staphylococcus aureus sepsis

Staphylococcal enterotoxin B (SEB) is an important member of the superantigen family, which exerts a number of pathological effects in the human, as well as susceptible animals. The present study was conducted to observe the time course and tissue distribution of SEB in postburn Staphylococcus aureus infection; meanwhile, the relationship between SEB and multiple organ dysfunction was also studied. Eighty-six male Wistar rats were randomly divided into four groups as follows: normal control group (n = 10); scald control group (n = 10); postburn sepsis group (n = 50) in which rats inflicted with 20% total body surface area (TBSA) III degrees scald followed by SEB-producing S. aureus challenge were further divided into 0.5-, 2-, 6-, 12-, and 24-h subgroups, with 10 rats in each subgroup; and SEB monoclonal antibody (MAb) treatment group (n = 16) in which a dose of 4 mg/kg SEB MAb was given intravenously just before S. aureus challenge, and the rats were further divided into 2- and 6-h subgroups. It was found that after thermal injury combined with S. aureus infection, SEB was widely distributed to the liver, kidneys, lungs, and heart, exacerbating the pathophysiology of multiple organ dysfunction induced by postburn sepsis. At the same time, the gene and protein expressions of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were also markedly upregulated in various tissues. Early treatment with SEB-specific MAb-MAb2D(1)-could markedly decrease SEB levels in plasma as well as in various tissues, and could significantly reduce the 6-h mortality rate (17.64% [3/17] vs. 55.6% [20/36], P = 0.02). These data suggested that neutralization of SEB is effective in ameliorating S. aureus sepsis and subsequent multiple organ damage, which might be attributed to its inhibitory effect on inflammatory mediator formation.

Significance of biopterin induction in rats with postburn Staphylococcus aureus sepsis

It has been demonstrated that biopterin, an essential cofactor of nitric oxide synthase (NOS), plays an important role in the pathogenesis of endotoxin-induced shock, yet its biological significance in gram-positive sepsis remains unclear. In this study, we adopted a rat model of postburn Staphylococcus aureus sepsis to investigate the potential role of biopterin in the pathogenesis of gram-positive sepsis. Wistar rats were inflicted with a 20% total body surface area (TBSA) full-thickness scald injury followed by S. aureus challenge, and then guanosine triphosphate-cyclohydrolase I (GTP-CHI) mRNA expression and biopterin levels in liver, kidneys, lungs, and heart were determined. We found that after S. aureus challenge, GTP-CHI gene expressions and biopterin levels were markedly upregulated in various tissues. Meanwhile, multiple organ dysfunction was induced by S. aureus challenge. It was shown that cardiac GTP-CHI mRNA expression and renal BH(4) levels were positively correlated with MB isoenzyme of creatine kinase (CK-MB) and creatinine (r = 0.892, P = 0.0012 and r = 0.9423, P = 0.0015, respectively). These results suggested that thermal injury combined with S. aureus challenge could induce de novo biosynthesis of biopterin, which might play a role in the development of multiple organ dysfunction syndrome secondary to postburn sepsis.

The mRNA expression patterns of tumor necrosis factor-α and TNFR-I in some vital organs after thermal injury

AIM: To investigate changes of tumor necrosis factor-α (TNF-α) and TNFR-I expression in vital organs and their significance in the pathogenesis of multiple organ damage associated with endogenous endotoxin following major burns.

METHODS: Wistar rats subjected to a 35% full-thickness scald injury were sacrificed at 12 h, 24 h, 48 h, and 72 h postburn, respectively. Meanwhile, eight rats were taken as normal controls. Tissue samples from liver, spleen, kidney, lung and intestine were collected to assay tissue endotoxin levels and measure TNF-α and TNFR-I expression. In addition, blood samples were obtained for the determination of organ function parameters.

RESULTS: Endotoxin levels in liver, spleen and lung increased markedly after thermal injury, with the highest level in liver. The gene expression of TNF-α in liver, lung and kidney was up-regulated after thermal injury, while the TNFR-I mRNA expression in liver, lung, kidney and intestine was shown decreased throughout the observation period. Thus, the mRNA expression ratio of TNF-α to TNFR-I was significantly increased postburn, particularly in pulmonary tissue (67-fold). In addition, the significant correlations between the expression of TNFR-I or the expression ratio of TNF-α/TNFR mRNA in liver tissue and serum aspartate aminotransferase levels were noted (P < 0.05-0.01). Similar results were also obtained between pulmonary TNF-α mRNA expression and myeloperoxidase activities (P < 0.01), whereas there was a highly negative correlation between levels of renal TNFR-I mRNA expression and serum creatinine.

CONCLUSION: Burn injury could result in the translocation of gut-derived endotoxin that was mainly distributed in the liver, spleen and lung. The translocated endotoxin then made the expression of TNF-α and TNFR-I mRNA up-regulated and down-regulated respectively in various organs, which might be involved in the pathogenesis of multiple organ damage following burns.

Effect of 2,4-diamino-6-hydroxy-pyrimidine on postburn Staphylococcus aureus sepsis in rats

OBJECTIVE

Guanosine triphosphate-cyclohydrolase I (GTP-CHI) is the first and rate-limiting enzyme for the de novo biosynthesis of biopterin. The objective of present study was to observe the effect of 2,4-diamino-6-hydroxy-pyrimidine (DAHP), an inhibitor of GTP-CHI, on the development of postburn Staphylococcus aureus sepsis.

DESIGN

A prospective, controlled animal study.

SETTING

A research laboratory in a hospital.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Fifty-six male Wistar rats were randomly divided into four groups as follows: normal control group (n = 10), scald control group (n = 10), postburn sepsis group (n = 20), and DAHP treatment group (n = 16). In the scald control group, rats were subjected to a 20% total body surface area third-degree scald injury and then were killed at 24 hrs. In the postburn sepsis group (n = 20), rats were inflicted with 20% total body surface area third-degree scald followed by Staphylococcus aureus challenge, and they were further divided into 2- and 6-hr groups. In the DAHP treatment group (n = 16), animals were intraperitoneally injected with a dose of 1 g/kg DAHP before Staphylococcus aureus challenge and then were further divided into 2- and 6-hr groups. Tissue samples from liver, kidneys, lungs, and heart were collected to determine GTP-CHI, inducible nitric oxide synthase, and tumor necrosis factor-alpha messenger RNA expression. Meanwhile, biopterin and nitric oxide concentrations in these tissues were also measured.

MEASUREMENTS AND MAIN RESULTS

After the scald injury followed by Staphylococcus aureus challenge, GTP-CHI messenger RNA expression and biopterin concentrations were significantly elevated in various tissues such as liver, heart, kidneys, and lungs, as were the values of inducible nitric oxide synthase messenger RNA expression and nitric oxide formation (p <.01). Pretreatment with DAHP significantly reduced GTP-CHI/biopterin induction (p <.05-.01), and the up-regulation of inducible nitric oxide synthase/nitric oxide was also suppressed. Furthermore, DAHP administration inhibited the gene expression of tumor necrosis factor-alpha. Two hours after septic challenge, tumor necrosis factor-alpha messenger RNA expression in liver, kidneys, and lungs in the DAHP-treated group was 35.7%, 37.3%, and 33.0% of that in the postburn septic group, respectively. Additionally, in animals without DAHP treatment, the 6-hr mortality rate was 55.6% (20 of 36), whereas it was only 25.0% in DAHP-treated animals (4 of 16, p =.08).

CONCLUSIONS

Early treatment with DAHP might be a potential strategy to prevent the development of postburn Staphylococcal sepsis, which appears to be associated with down-regulation of biopterin and nitric oxide formation by DAHP.

Lipopolysaccharide-binding protein and lipopolysaccharide receptor CD14 gene expression after thermal injury and its potential mechanism(s)

BACKGROUND

We hypothesized that lipopolysaccharide-binding protein (LBP) and lipopolysaccharide receptor CD14 would present a pair of key molecules in pathophysiologic alterations induced by low concentrations of endotoxin after trauma. The aim of this study was to investigate the relationship between endotoxin translocation and tissue LBP/CD14 messenger ribonucleic acid (mRNA) expression after burn injury, and to define the potential role of LBP/CD14 in mediating inflammatory mediator induction, as well as the pathogenesis of organ damage.

METHODS

Wistar rats were subjected to a 35% full-thickness scald injury, and tissue samples from liver, kidneys, lungs, and intestine were collected to measure LBP/CD14 and tumor necrosis factor-alpha (TNF-alpha) mRNA expression. Peritoneal macrophages were harvested by peritoneal lavage to determine CD14 mRNA expression.

RESULTS

It was found that endotoxin levels in liver, spleen, and lung increased markedly after thermal injury, with the highest level in liver. Both tissue LBP and CD14 mRNA expression increased markedly after burns, peaking at 12 hours, and then decreasing gradually. At 48 hours, LBP gene expression had a tendency to the baseline level, whereas CD14 mRNA expression increased again. Likewise, CD14 mRNA levels were up-regulated markedly in peritoneal macrophages. Conversely, gene expression of TNF-alpha in tissues elevated markedly after acute insults. There were positive correlations between lipopolysaccharide levels and LBP/CD14 mRNA as well as TNF-alpha mRNA expression in tissues. Similar results were also obtained between CD14, TNF-alpha mRNA expression in liver tissue and liver function parameters, and between pulmonary TNF-alpha mRNA and myeloperoxidase activities (p < 0.01).

CONCLUSION

Thermal injury per se can markedly up-regulate both LBP and CD14 gene expression in various organs. Excessive LBP and CD14 mRNA expression might be associated with enhanced synthesis and release of TNF-alpha stimulated by endotoxin translocation after major burns.

The significance of changes in high mobility group-1 protein mRNA expression in rats after thermal injury

There has been a widespread impression that tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mediate the toxicity of high doses of lipopolysaccharide (LPS, endotoxin) and are key factors in septic shock. However, the clinical efficacy of treatment with antagonists of TNF-alpha and IL-1beta is still controversial, suggesting that mediators other than TNF-alpha and IL-1beta might contribute causally to endotoxin-induced death. Recent studies implicated high mobility group-1 (HMG-1) protein as a late mediator of endotoxin lethality in mice. However, the role of HMG-1 in mediating multiple organ damage-associating trauma has not been studied. This study was designed to investigate changes in HMG-1 gene expression in vital organs, and its potential role in mediating multiple organ damage following major burns. Wistar rats were subjected to a 35 percent full-thickness thermal injury, and randomly divided into three groups as follows: normal controls (n = 7), thermal injury (n = 24), and recombinant bactericidal/permeability-increasing protein (rBPI21) treatment (n = 12). Tissue samples from liver and lungs were collected to measure tissue endotoxin levels and HMG-1 mRNA expression. In addition, blood samples were obtained for measurement of organ function parameters. Our data demonstrated a significant increase in HMG-1 gene expression in tissues at 24 h postburn, which remained markedly elevated up to 72 h after thermal injury (P< 0.05-0.01). Treatment with rBPI21 could significantly decrease tissue HMG-1 mRNA expression in the liver and lung (P < 0.01). In addition, there were high positive correlations between hepatic HMG-1 mRNA and serum aminoleucine transferase (ALT) and aspartate aminotransferase (AST) levels, and also between pulmonary HMG-1 mRNA and myeloperoxidase activities (P < 0.05-0.01). Taken together, these findings indicate that thermal injury per se can markedly enhance HMG-1 gene expression in various organs. Up-regulation of HMG-1 expression may be involved in the pathogenesis of endogenous endotoxin-mediated multiple organ damage secondary to major burns.