Nrf2 protects against TWEAK-mediated skeletal muscle wasting

Skeletal muscle (SM) regeneration after injury is impaired by excessive inflammation. Particularly, the inflammatory cytokine tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is a potent inducer of skeletal muscle wasting and fibrosis. In this study we investigated the role of Nrf2, a major regulator of oxidative stress defence, in SM ischemia/reperfusion (I/R) injury and TWEAK induced atrophy. We explored the time-dependent expression of TWEAK after I/R in SM of Nrf2-wildtype (WT) and knockout (KO) mice. Nrf2-KO mice expressed significant higher levels of TWEAK as compared to WT mice. Consequently, Nrf2-KO mice present an insufficient regeneration as compared to Nrf2-WT mice. Moreover, TWEAK stimulation activates Nrf2 in the mouse myoblast cell line C2C12. This Nrf2 activation inhibits TWEAK induced atrophy in C2C12 differentiated myotubes. In summary, we show that Nrf2 protects SM from TWEAK-induced cell death in vitro and that Nrf2-deficient mice therefore have poorer muscle regeneration.

Role of the cathelicidin-related antimicrobial peptide in inflammation and mortality in a mouse model of bacterial meningitis

Antimicrobial peptides (AP) are important components of the innate immune system, yet little is known about their expression and function in the brain. Our previous work revealed upregulated gene expression of cathelicidin-related AP (CRAMP) following bacterial meningitis in primary rat glial cells as well as bactericidal activity against frequent meningitis-causing bacteria. However, the effect of cathelicidin expression on the progression of inflammation and mortality in bacterial meningitis remains unknown. Therefore, we used CRAMP-deficient mice to investigate the effect of CRAMP on bacterial growth, inflammatory responses and mortality in meningitis. Meningitis was induced by intracerebral injection of type 3 Streptococcus pneumoniae. The degree of inflammation was analyzed in various brain regions by means of immunohistochemistry and real-time RT-PCR. CRAMP deficiency led to a higher mortality rate that was associated with increased bacterial titers in the cerebellum, blood and spleen as well as decreased meningeal neutrophil infiltration. CRAMP-deficient mice displayed a higher degree of glial cell activation that was accompanied by a more pronounced proinflammatory response. Taken together, this work provides insight into the important role of CRAMP as part of the innate immune defense against pathogens in bacterial CNS infections.

A novel laser-Doppler flowmetry assisted murine model of acute hindlimb ischemia-reperfusion for free flap research

Suitable and reproducible experimental models of translational research in reconstructive surgery that allow in-vivo investigation of diverse molecular and cellular mechanisms are still limited. To this end we created a novel murine model of acute hindlimb ischemia-reperfusion to mimic a microsurgical free flap procedure. Thirty-six C57BL6 mice (n = 6/group) were assigned to one control and five experimental groups (subject to 6, 12, 96, 120 hours and 14 days of reperfusion, respectively) following 4 hours of complete hindlimb ischemia. Ischemia and reperfusion were monitored using Laser-Doppler Flowmetry. Hindlimb tissue components (skin and muscle) were investigated using histopathology, quantitative immunohistochemistry and immunofluorescence. Despite massive initial tissue damage induced by ischemia-reperfusion injury, the structure of the skin component was restored after 96 hours. During the same time, muscle cells were replaced by young myotubes. In addition, initial neuromuscular dysfunction, edema and swelling resolved by day 4. After two weeks, no functional or neuromuscular deficits were detectable. Furthermore, upregulation of VEGF and tissue infiltration with CD34-positive stem cells led to new capillary formation, which peaked with significantly higher values after two weeks. These data indicate that our model is suitable to investigate cellular and molecular tissue alterations from ischemia-reperfusion such as occur during free flap procedures.

PP021. The role of the transcription factor Nrf2 in the murine placental development

INTRODUCTION

The placenta is the key organ for successful pregnancy and fetal growth. Oxidative stress during early human placental development is associated with pregnancy-related disorders. The transcription of many antioxidative-genes is mediated mainly through the transcription factor Nrf2. Furthermore, a link between Nrf2, vascular homeostasis and extravillous trophoblast invasion has been discussed.

OBJECTIVES

Here, we investigated the placental phenotype, placental and fetal weight of the Nrf2 knockout (Nrf2(-/-)) and wild type (Nrf2(+/+)) mice and the vascular function of these placentas around embryonic day 18.5.

METHODS

We performed H&E, Periodic Acid Schiff (PAS) and immunohistochemistry of paraffin-embedded mouse placenta samples.

RESULTS

There is no significant difference in both placental and fetal weight of both geno types (Nrf2(-/-) and Nrf2(+/+)). Phenotypic analysis of ED 18.5 placentas showed presence of trophoblast clusters in the labyrinth and frequent enlarged maternal blood lacunae. Furthermore, Nr2(-/-) showed increased levels in the lipid peroxidation product 4-hydroxinonoeal (4-HNE), which is a sensitive marker of oxidative damage and lipid peroxidation.

CONCLUSION

This data point out the necessity of a functional Nrf2 for placental development, as it may interact with the differentiation of the trophoblast lineage from one side and to diminish the oxidative damage during pregnancy from the other side.

PP019. A new player in preeclampsia: The NF-E2-related factor 2 (NRF2)

INTRODUCTION

Preeclampsia PE is characterized by diminished antioxidant capacity. These enzymes are mainly regulated via the transcription factor Nrf2.

OBJECTIVES

PE is associated with an increase in Nrf2 activity. Nrf2 involves also in the vascular homeostasis during PE. Respective hemodisturbances have been associated with impaired invasion of the extravillous trophoblast EVT in early onset IUGR associated with PE. To test this link, we studied in vitro the interaction between Nrf2 and VEGF, then their expression was determined in third trimester placental beds in cases of severe early onset IUGR/PE.

METHODS

BeWo cells were used in the in vitro study.Western blot; ELISA and Dual Luciferase assay were applied. Full-thickness uterine tissues from 6 healthy and 6 women with severe early onset IUGR/PE were used to study the expression of VEGF, Nrf2 and 4-HNE in the EVT.

RESULTS

Nrf2-activation and its downstream target protein HO-1 augmented CO production, which in turn up-regulated the expression of VEGF. EVT in cases with IUGR/PE showed increased expression of Nrf2 and decreased VEGF intensity.

CONCLUSION

In early onset IUGR/PE the EVT experience oxidative stress and try to counteract this by increased expression of Nrf2. However, since these cells fail to up-regulate VEGF, Nrf2-activation does not occur, leading to further trophoblast damage. At the same time, in vitro data show a protective role of the Nrf2/HO-1 pathway, which may have a therapeutic potential in PE.

PP020. Evidence of a preventive role of Nrf2 in preeclampsia

INTRODUCTION

Smoking during pregnancy is associated with lower preeclampsia risk. This has been mainly explained through the effect of carbon monoxide CO.

OBJECTIVES

Recent studies showed that the activation of heme oxygenase-1 HO-1 and consequently its metabolite CO in cultured cells mediated an inhibition of sFlt-1 and sEng release, and an up-regulation of the endogenous VEGF. The transcriptional regulation of the HO-1 gene is majorly regulated through the transcription factor Nrf2. The aim of this study was to investigate in vitro the effect of HO-1-activation via Nrf2 on the pro- and anti-angiogenic factors.

METHODS

BeWo cells and HUVECs endothelial cells were used to study the angiogenic effect of Nrf2-activation. ELISA, scratch and tube formation assay were mainly applied.

RESULTS

The activation of HO-1 via Nrf2 lead to an increase in the protein levels of VEGF (control 64.75pg/ml±4.3; Sulforaphane-treated cells 128.2pg/ml±6.5 p<0.005) and decrease in the augmented sFlt-1 in the supernatant of the treated cells (control 186.3pg/ml±28.7; H2O2-treatment 2026pg/ml±64, co-treatment with H2O2 and Sulforaphane 1200pg/ml±19.7 p<0.01). Up-regulation of HO-1/CO enhanced tube formation and migration of the endothelial cells.

CONCLUSION

The activation of HO-1/CO via Nrf2 inducer such as sulforaphane inhibited in vitro the release of sFlt-1, thus the activation of Nrf2 during the first trimester may improve the balance of the pro- and anti-angiogenic factors.

Intraarticular injection of platelet-rich plasma reduces inflammation in a pig model of rheumatoid arthritis of the knee joint

OBJECTIVE

Treatment options for rheumatoid arthritis range from symptomatic approaches to modern molecular interventions such as inhibition of inflammatory mediators. Inhibition of inflammation by platelet-rich plasma (PRP) has been proposed as a treatment for tendinitis and osteoarthritis. The present study was undertaken to investigate the effect of PRP on antigen-induced arthritis (AIA) of the knee joint in a large animal model.

METHODS

Six-month-old pigs (n = 10) were systemically immunized by bovine serum albumin (BSA) injection, and arthritis was induced by intraarticular BSA injection. PRP was injected into the knee joints of 5 of the animals after 2 weeks. An additional 5 animals received no systemic immunization (controls). Signs of arthritis were documented by plain histologic analysis, Safranin O staining, and immunohistochemistry analysis for type II collagen (CII), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF). Interleukin-1β (IL-1β), IL-6, tumor necrosis factor α (TNFα), VEGF, and insulin-like growth factor 1 (IGF-1) protein content was measured by Luminex assay.

RESULTS

In the pigs with AIA, plain histologic analysis revealed severe arthritic changes in the synovium. Safranin O and CII staining showed decreased proteoglycan and CII content in cartilage. Immunohistochemistry analysis revealed increased levels of IL-6 and VEGF in synovium and cartilage, and protein concentrations of IL-6, VEGF, IL-1β, and IGF-1 in synovium and cartilage were elevated as well; in addition, TNFα protein was increased in cartilage. Treatment with PRP led to attenuation of these arthritic changes in the synovium and cartilage.

CONCLUSION

We have described a porcine model of AIA. Experiments using this model demonstrated that PRP can attenuate arthritic changes as assessed histologically and based on protein synthesis of typical inflammatory mediators in the synovial membrane and cartilage.

The effect of platelet rich plasma on angiogenesis in ischemic flaps in VEGFR2-luc mice

To improve skin flap healing, one promising strategy in reconstructive surgery might be to optimize platelet rich plasma (PRP) bioactivity and the ischemia-altered expression of genes. We studied both the effect of PRP on ischemic flaps, and whether in vivo bioluminescence imaging (BLI) is a suitable method for the longitudinal monitoring of angiogenesis in surgical wounds. Axial murine skin flaps were created in four experimental groups. In vivo measurements of VEGFR2 expression levels were made every other day until the 14th day. The local VEGF level and microvessel density were quantified on the 14th day via ELISA and immunohistochemistry, and flap survival rates were measured. We demonstrated that PRP and induced ischemia have a beneficial influence on angiogenesis and flap healing. Combining the two resulted in a significantly robust increase in angiogenesis and flap survival rate that was corroborated by bioluminescence imaging of VEGFR2 activity. This study shows that angiogenic effects of PRP may be potentialized by the stimulus of induced ischemia during free flap harvesting, and thus the two procedures appear to have a synergistic effect on flap healing. This study further demonstrates that BLI of modulated genes in reconstructive surgery is a valuable model for longitudinal in vivo evaluation of angiogenesis.

Involvement of formyl peptide receptors in receptor for advanced glycation end products (RAGE)--and amyloid beta 1-42-induced signal transduction in glial cells

Background

Recent studies suggest that the chemotactic G-protein-coupled-receptor (GPCR) formyl-peptide-receptor-like-1 (FPRL1) and the receptor-for-advanced-glycation-end-products (RAGE) play an important role in the inflammatory response involved in neurodegenerative disorders such as Alzheimer’s disease (AD).

Therefore, the expression and co-localisation of mouse formyl peptide receptor (mFPR) 1 and 2 as well as RAGE in an APP/PS1 transgenic mouse model using immunofluorescence and real-time RT-PCR were analysed. The involvement of rat or human FPR1/FPRL1 (corresponds to mFPR1/2) and RAGE in amyloid-β 1–42 (Aβ1-42)-induced signalling were investigated by extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation. Furthermore, the cAMP level in primary rat glial cells (microglia and astrocytes) and transfected HEK 293 cells was measured. Formyl peptide receptors and RAGE were inhibited by a small synthetic antagonist WRW4 and an inactive receptor variant delta-RAGE, lacking the intracytoplasmatic domains.

Results

We demonstrated a strong increase of mFPR1/2 and RAGE expression in the cortex and hippocampus of APP/PS1 transgenic mice co-localised to the glial cells. In addition, the Aβ1-42-induced signal transduction is dependant on FPRL1, but also on FPR1. For the first time, we have shown a functional interaction between FPRL1/FPR1 and RAGE in RAGE ligands S100B- or AGE-mediated signalling by ERK1/2 phosphorylation and cAMP level measurement. In addition a possible physical interaction between FPRL1 as well as FPR1 and RAGE was shown with co-immunoprecipitation and fluorescence microscopy.

Conclusions

The results suggest that both formyl peptide receptors play an essential role in Aβ1-42-induced signal transduction in glial cells. The interaction with RAGE could explain the broad ligand spectrum of formyl peptide receptors and their important role for inflammation and the host defence against infections.

CpG oligodeoxynucleotides induce the expression of the antimicrobial peptide cathelicidin in glial cells

During bacterial infections, antimicrobial peptides are synthesised as an important part of the innate immune system. However, expression and function in the central nervous system (CNS) need further investigations. The aim of this study was to examine the involvement of the pattern-recognition-receptor toll-like receptor 9 (TLR9) in the expression of the cathelin-related antimicrobial peptide (CRAMP) and to characterise the participating signal transduction pathways. In primary TLR9 deficient and wildtype mice astrocytes as well as microglia cells, the expression of CRAMP after treatment with the TLR9 agonist unmethylated cytosine-guanine oligodeoxynucleotide motifs (CpG-DNA) was examined in vitro. In vivo CRAMP expression after intraventricular infusion of CpG-DNA in TLR9 deficient and wildtype mice as well as in mice with pneumococcal meningitis localised in glial cells was determined. Furthermore, the regulation of different signal transduction pathways involved in CpG-DNA-induced CRAMP expression in glial cells was analysed. An in vitro and in vivo CpG-DNA-induced increase of CRAMP expression in astrocytes and microglia cells using real time RT-PCR and immunofluorescence was demonstrated. Different signal transduction pathways such as mitogen-activated protein kinases and inflammatory mediated pathways are involved in the expression of CRAMP in primary glial cells. Interestingly, TLR9-deficient glial cells showed a reduced but not completely abolished CRAMP mRNA expression and ERK1/2 phosphorylation in response to CpG-DNA treatment. On the other side in vivo, TLR9 deletion did not change CRAMP expression after bacterial infection. In conclusion, our results show that TLR9 can induce the expression of antimicrobial peptides such as CRAMP in response to bacterial DNA motifs in primary glial cells. Additional findings suggest also that CpG-DNA-induced effects are not only mediated by TLR9, but also mediated by other pattern recognition receptors.

Sulforaphane has opposing effects on TNF-alpha stimulated and unstimulated synoviocytes

INTRODUCTION

Rheumatoid arthritis (RA) is characterized by progressive inflammation associated with rampantly proliferating synoviocytes and joint destruction due to oxidative stress. Recently, we described nuclear factor erythroid 2-related factor 2 (Nrf2) as a major requirement for limiting cartilage destruction. NF-κB and AP-1 are the main transcription factors triggering the inflammatory progression in RA. We used sulforaphane, an isothiocyanate, which is both an Nrf2 inducer and a NF-κB and AP-1 inhibitor.

METHODS

Cultured synoviocytes were stimulated with sulforaphane (SFN) with or without TNF-α pre-treatment. NF-κB, AP-1, and Nrf2 activation was investigated via dual luciferase reporter gene assays. Matrix metalloproteinases (MMPs) were measured via zymography and luminex technique. Cytokine levels were detected using ELISA. Cell viability, apoptosis and caspase activity were studied. Cell proliferation was analysed by real-time cell analysis.

RESULTS

SFN treatment decreased inflammation and proliferation dose-dependently in TNF-α-stimulated synoviocytes. SFN did not reduce MMP-3 and MMP-9 activity or expression significantly. Interestingly, we demonstrated that SFN has opposing effects on naïve and TNF-α-stimulated synoviocytes. In naïve cells, SFN activated the cytoprotective transcription factor Nrf2. In marked contrast to this, SFN induced apoptosis in TNF-α-pre-stimulated synoviocytes.

CONCLUSIONS

We were able to show that SFN treatment acts contrary on naïve and inflammatory synoviocytes. SFN induces the cytoprotective transcription factor Nrf2 in naïve synoviocytes, whereas it induces apoptosis in inflamed synoviocytes. These findings indicate that the use of sulforaphane might be considered as an adjunctive therapeutic strategy to combat inflammation, pannus formation, and cartilage destruction in RA.

A role for Nrf2 in redox signalling of the invasive extravillous trophoblast in severe early onset IUGR associated with preeclampsia

BACKGROUND

Preeclampsia (PE) is characterized by increased lipid oxidation and diminished antioxidant capacity, while intrauterine growth restriction (IUGR) is characterized by impaired invasion of the extravillous trophoblast. Vascular endothelial growth factor (VEGF) has been reported to be altered in preeclampsia. A relationship between VEGF and nuclear factor erythroid 2-related factor-2 (Nrf2) has been shown in vitro, where VEGF prevents oxidative damage via activation of the Nrf2 pathway. In this study the expression of Nrf2, VEGF and 4-hydroxynonenal (4-HNE), was determined in interstitial and endovascular/intramural extravillous trophoblast (EVT) in normal pregnancies and those complicated by severe early onset IUGR associated with preeclampsia IUGR/PE.

MATERIALS AND METHODS

Full-thickness uterine tissues derived from caesarean hysterectomies performed in 5 healthy normotensive women delivering term infants and 6 women with severe early onset IUGR with preeclampsia (29-34 weeks gestation) were analyzed. Interstitial and endovascular extravillous trophoblast were quantified after immunohistochemical staining of paraffin sections using antibodies against Nrf2, 4-HNE, VEGF, and cytokeratin 7.

RESULTS

Uterine tissues from women suffering from severe early onset IUGR/PE were characterized by reduced invasion of extravillous trophoblast into the endometrial and myometrial segments of spiral arteries in the placental bed. Extravillous trophoblast showed an increased cytoplasmic expression of Nrf2 and 4-HNE in IUGR/PE cases. The increased expression of Nrf2 in cases of IUGR/PE was associated with decreased expression of VEGF in these cells compared to controls.

CONCLUSION

Our data suggests that besides villous cytotrophoblast, also the extravillous trophoblast is a source of Nrf2-dependent genes. VEGF deficiency may cause higher oxidative stress in extravillous trophoblast in cases with IUGR/PE. The resulting reduced basal defence against oxidative stress and the higher vulnerability to oxidative damage may play a role in the limited trophoblast invasion into spiral arteries in cases suffering from severe early onset IUGR/PE.

PP119. The role of the nuclear factor erythroid 2-related factor 2 (Nrf2) in preeclampsia

INTRODUCTION

Preeclampsia is a multi-organ syndrome characterized by maternal endothelial damage, is an independent long-term risk factor for hypertension and cardiovascular disease.

OBJECTIVES

In animal models the administration of the Vascular Endothelial Growth Factor (VEGF) could reverse the hypertensive signs accompanying this disease. In addition VEGF is implicated in placental oxidative stress during preeclampsia. One of the major cellular defence mechanisms against oxidative stress is the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2). Therefore, the activation of Nrf2 up regulates the HO-1/CO system. The principal aim of this work is to investigate whether the activation of Nrf2 raises VEGF levels by up regulation of CO release.

METHODS

This study took place in vitro, the choriocarcinoma cell line BeWo cells and the primary human umbilical vein endothelial cells (HUVECs) were used to study the relationship between VEGF and an Nrf2 inducer Sulforaphane, a naturally occurring compound derived from broccoli. ELISA, Western blot assay and the Dual Luciferase Assay were both mainly applied for protein and VEGF activity analysis.

RESULTS

It was found that activation of HO-1 expression via Nrf2/ARE pathway augmented the production of CO, which in turn up-regulated the gene expression of VEGF, and down regulated the production of the antiangiogenic protein, the VEGF antagonist sFlt-1.

CONCLUSION

Nrf2 driven HO-1 expression elevates the levels of VEGF via CO production. In particular, activating of Nrf2 via sulforaphane, may have therapeutic potential in preeclampsia.

PP015. Differential expression of Nrf2 and VEGF in human placental beds from normal and pregnancies complicated with preeclampsia and IUGR

INTRODUCTION

Impaired trophoblast invasion into the uteroplacental arteries is accompanied with an evidence of oxidative stress in the extravillous trophoblast in preeclampsia complicated with IUGR.

OBJECTIVES

Preeclampsia is characterised by increased lipid oxidation and diminished antioxidant capacity; recently, we have shown that PE is associated with an increased expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) in villous cytotrophoblast. A possible relationship between the vascular endothelial growth factor (VEGF) and Nrf2 was established in vitro and the activation of Nrf2 pathway could lead to upregulation of VEGF synthesis through the induction of Nrf2-dependent Heme oxygenase-1 (HO-1). In this study the expression of Nrf2 and VEGF was determined in the interstitial and intramural extravillous trophoblast in normal pregnancies and those complicated by preeclampsia and intra-uterine growth restriction (IUGR).

METHODS

Full-thickness uterine tissues were obtained from caesarean hysterectomies performed in 5 healthy normotensive women delivering term infants and from 5 women with severe early-onset preeclampsia and IUGR (29-34 week's gestation). The interstitial and intramural trophoblasts were studied by immunohistochemical analysis of paraffin sections stained with anti VEGF and anti Nrf2.

RESULTS

Cases suffering from preeclampsia with IUGR were characterised by reduced invasion of extravillous trophoblast into uteroplacental arteries in the endometrial and myometrial segments. In addition, these cells showed an increased expression of Nrf2 in the pathological sections. The overexpression of Nrf2 in cases with preeclampsia was associated with restricted expression of VEGF in these cells compared to controls.

CONCLUSION

Our data suggest that besides villous cytotrophoblast, also the extravillous trophoblast is a source of Nrf2-dependent genes. VEGF deficiency may cause higher oxidative stress in extravillous trophoblast in cases with preeclampsia with IUGR. The resulting reduced basal defence against oxidative stress and the higher vulnerability to oxidative damage may play a role in the limited trophoblast invasion into uteroplacental arteries in cases suffering from early onset preeclampsia and IUGR.

Mechanisms of proximal hamstring rupture in a non-athlete healthy middle-aged female

PURPOSE

To present an explicatory pathophysiological model for the rare clinical case of a total proximal hamstring rupture for the first time in the literature.

METHODS

A non-athletic healthy female (49 years) experienced a complete rupture of the right conjoint tendon of the biceps femoris (long head) and semitendinosus muscle while slipping down a lawn-covered slope (eccentric hip flexion and knee extension during stance phase of gait after heel-strike). A hamstring rupture was diagnosed by clinical examination and confirmed by magnet resonance imaging (MRI). Surgical reattachment of the conjoint tendon to the ischial tuberosity was performed. One year after surgery, she experienced no pain or functional impairment.

RESULTS

Histological analysis and immune-histochemical staining (vascular endothelial growth factor - receptor 2) of a biopsy taken intra-operatively revealed signs of fibroblast proliferation and vasculoneogenesis with absence of inflammatory changes indicating that repairing mechanisms and tissue remodeling had been taking place.

CONCLUSION

This case report provides evidence for the hypothesis that micro-injuries induce repairing mechanisms and thus tissue remodeling which leads to consecutive tissue weakening and mechanical failure during a non-adequate trauma. Micro-injuries can occur during leisure activities and remain clinically invisible until rupture.

Impact of Nrf2 on esophagus epithelium cornification

BACKGROUND

Nrf2 is a transcription factor that is known to maintain cellular defense against the toxicity of electrophiles and reactive oxygen species (ROS).

METHODS

We show an effect of Nrf2 deficiency on the histology of the esophagus of Nrf2 knockout mice.

RESULTS

Quantitative analysis of esophageal cornification via hematoxylin and eosin (H&E) staining revealed significantly (P=0.0127) decreased stratification in Nrf2 knockout mice compared with wild-type controls. In addition, we show that Nrf2 is expressed solely in the stratum spinosum and not in the stratum basale of the epidermis. This expression pattern is exactly the same as those described for keratin K6 and K16.

CONCLUSIONS

We conclude that Nrf2 regulates the cornification of epithelia and may play a role in callus formation and wound healing of the skin, as well as in skin aging.

Multiple trauma induces serum production of host defence peptides

Today multiple trauma still is associated with a high mortality. Although severe open fractures and wounds can give rise to local infections and sepsis, the overall infection rate of multiply injured patients is surprisingly low. We have investigated serum of multiply injured patients with respect to antibacterial properties and screened for host defence peptides (HDP) that constitute a class of fast acting and rapidly available molecules preventing bacterial infection. Serum specimens were obtained from multiply injured patients. Radial diffusion assays were performed to investigate antimicrobial properties. Ultrafiltration and heat-inactivation were used to rule out antimicrobial activity of large proteins i.e. complement factors. ELISA was performed to analyse serum concentrations of the human beta-defensins 2 and 3 (hBD-2 and hBD-3), LL-37 and the proinflammatory cytokines interferon-gamma (IFN-γ) and interleukin-6 (IL-6). Serum of multiply injured patients showed greater zones of inhibition in antimicrobial testing against Gram negative und positive bacteria. This effect was mediated by proteins smaller than 10 kDa, inactivation of the complement system does not significantly reduce antibacterial action. hBD-2, hBD-3 and LL-37 concentrations were significantly elevated after trauma and followed different characteristic concentration curves. Similar patterns of concentration profiles were recorded for hBD-2/IL-6 and hBD-3/IFN-γ suggesting a stimulatory influence within their induction process. With this study we provide evidence, that serum of multiply injured patients has by far higher antibacterial capacity than that of healthy donors. As possible mediators we have detected the HDP hBD-2, hBD-3 and LL-37 and their inducers in serum of multiply injured patients.