Potential Biomarkers for the Earlier Diagnosis of Kidney and Liver Damage in Acute Intermittent Porphyria

Acute intermittent porphyria (AIP) is an inherited metabolic disorder associated with complications including kidney failure and hepatocellular carcinoma, probably caused by elevations in the porphyrin precursors porphobilinogen (PBG) and delta-aminolevulinic acid (ALA). This study explored differences in modern biomarkers for renal and hepatic damage between AIP patients and controls. Urine PBG testing, kidney injury panels, and liver injury panels, including both routine and modern biomarkers, were performed on plasma and urine samples from AIP cases and matched controls (50 and 48 matched pairs, respectively). Regarding the participants' plasma, the AIP cases had elevated kidney injury marker-1 (KIM-1, p = 0.0002), fatty acid-binding protein-1 (FABP-1, p = 0.04), and α-glutathione S-transferase (α-GST, p = 0.001) compared to the matched controls. The AIP cases with high PBG had increased FABP-1 levels in their plasma and urine compared to those with low PBG. In the AIP cases, KIM-1 correlated positively with PBG, CXCL10, CCL2, and TCC, and the liver marker α-GST correlated positively with IL-13, CCL2, and CCL4 (all p < 0.05). In conclusion, KIM-1, FABP-1, and α-GST could represent potential early indicators of renal and hepatic damage in AIP, demonstrating associations with porphyrin precursors and inflammatory markers.

Complement C3b contributes to Escherichia coli-induced platelet aggregation in human whole blood

Introduction

Platelets have essential functions as first responders in the immune response to pathogens. Activation and aggregation of platelets in bacterial infections can lead to life-threatening conditions such as arterial thromboembolism or sepsis-associated coagulopathy.

Methods

In this study, we investigated the role of complement in Escherichia coli (E. coli)-induced platelet aggregation in human whole blood, using Multiplate^® aggregometry, flow cytometry, and confocal microscopy.

Results and Discussion

We found that compstatin, which inhibits the cleavage of complement component C3 to its components C3a and C3b, reduced the E. coli-induced platelet aggregation by 42%-76% (p = 0.0417). This C3-dependent aggregation was not C3a-mediated as neither inhibition of C3a using a blocking antibody or a C3a receptor antagonist, nor the addition of purified C3a had any effects. In contrast, a C3b-blocking antibody significantly reduced the E. coli-induced platelet aggregation by 67% (p = 0.0133). We could not detect opsonized C3b on platelets, indicating that the effect of C3 was not dependent on C3b-fragment deposition on platelets. Indeed, inhibition of glycoprotein IIb/IIIa (GPIIb/IIIa) and complement receptor 1 (CR1) showed that these receptors were involved in platelet aggregation. Furthermore, aggregation was more pronounced in hirudin whole blood than in hirudin platelet-rich plasma, indicating that E. coli-induced platelet aggregation involved other blood cells. In conclusion, the E. coli-induced platelet aggregation in human whole blood is partly C3b-dependent, and GPIIb/IIIa and CR1 are also involved in this process.

A Novel Porcine Model of Ischemia-Reperfusion Injury After Cross-Clamping the Thoracic Aorta Revealed Substantial Cardiopulmonary, Thromboinflammatory and Biochemical Changes Without Effect of C1-Inhibitor Treatment

Ischemic injury worsens upon return of blood and innate immunity including the complement system play a central role in ischemia-reperfusion injury (IRI) as in thoracic aortic surgery. Complement component1 inhibitor (C1-INH) has been shown to reduce IRI and is a broad-acting plasma cascade inhibitor. We established a new porcine model of IRI by cross-clamping the thoracic aorta and evaluated the global changes occurring in organ function, systemic inflammatory response and organ damage with or without treatment with C1-INH-concentrate. Twenty-four piglets (8.8-11.1 kg) underwent 45 minutes clamping of the thoracic aorta at the Th8 level. Upfront 12 piglets received human saline and 12 received C1-INH (250 IU/kg) intravenously. Three sham animals received thoracic opening without clamping. Reperfusion lasted 5 hours. We studied ten cardiorespiratory markers, three hematologic markers, eleven inflammatory markers, and twelve organ damage markers over the whole experimental period. Postmortem tissue homogenates from seven organs were examined for inflammatory markers and analysed by two-way repeated-measures ANOVA, area under the curve or unpaired t-tests. By excluding sham and combining treated and untreated animals, the markers reflected a uniform, broad and severe organ dysfunction. The mean and range fold change from before cross-clamp onset to maximum change for the different groups of markers were: cardiorespiratory 1.4 (0.2-3.7), hematologic 1.9 (1.2-2.7), plasma inflammatory 19.5 (1.4-176) and plasma organ damage 2.9 (1.1-8.6). Treatment with C1-INH had only a marginal effect on the IRI-induced changes, reaching statistical significance only for the plasma complement activation product TCC (p=0.0083) and IL-4 (p=0.022) and INF-α (p=0.016) in the colon tissue. In conclusion, the present novel model of porcine global IRI is forceful with regards to central markers and could generally be applicable for pathophysiological studies. C1-INH treatment had no significant effect, but the model allows for future testing of other drugs attenuating IRI globally.

Blood Transcriptome Analysis of Septic Patients Reveals a Long Non-Coding Alu-RNA in the Complement C5a Receptor 1 Gene

Many severe inflammation conditions are complement-dependent with the complement component C5a-C5aR1 axis as an important driver. At the RNA level, the blood transcriptome undergoes programmed expression of coding and long non-coding RNAs to combat invading microorganisms. Understanding the expression of long non-coding RNAs containing Alu elements in inflammation is important for reconstructing cell fate trajectories leading to severe disease. We have assembled a pipeline for computation mining of new Alu-containing long non-coding RNAs by intersecting immune genes with known Alu coordinates in the human genome. By applying the pipeline to patient bulk RNA-seq data with sepsis, we found immune genes containing 48 Alu insertion as robust candidates for further study. Interestingly, 1 of the 48 candidates was located within the complement system receptor gene C5aR1 and holds promise as a target for RNA therapeutics.

Air Bubbles Activate Complement and Trigger Hemostasis and C3-Dependent Cytokine Release Ex Vivo in Human Whole Blood

Air bubbles trigger a C3-driven thromboinflammation in human whole blood.

Blocking C3, but not C5, attenuates the air-induced inflammation.

Avoiding ambient air in test tubes attenuates thromboinflammation.

Venous air embolism, which may complicate medical and surgical procedures, activates complement and triggers thromboinflammation. In lepirudin-anticoagulated human whole blood, we examined the effect of air bubbles on complement and its role in thromboinflammation. Whole blood from 16 donors was incubated with air bubbles without or with inhibitors of C3, C5, C5aR1, or CD14. Complement activation, hemostasis, and cytokine release were measured using ELISA and quantitative PCR. Compared with no air, incubating blood with air bubbles increased, on average, C3a 6.5-fold, C3bc 6-fold, C3bBbP 3.7-fold, C5a 4.6-fold, terminal complement complex sC5b9 3.6-fold, prothrombin fragments 1+2 (PTF1+2) 25-fold, tissue factor mRNA (TF-mRNA) 26-fold, microparticle tissue factor 6.1-fold, β-thromboglobulin 26-fold (all p < 0.05), and 25 cytokines 11-fold (range, 1.5–78-fold; all p < 0.0001). C3 inhibition attenuated complement and reduced PTF1+2 2-fold, TF-mRNA 5.4-fold, microparticle tissue factor 2-fold, and the 25 cytokines 2.7-fold (range, 1.4–4.9-fold; all p < 0.05). C5 inhibition reduced PTF1+2 2-fold and TF-mRNA 12-fold (all p < 0.05). C5 or CD14 inhibition alone reduced three cytokines, including IL-1β (p = 0.02 and p = 0.03). Combined C3 and CD14 inhibition reduced all cytokines 3.9-fold (range, 1.3–9.5-fold; p < 0.003) and was most pronounced for IL-1β (3.2- versus 6.4-fold), IL-6 (2.5- versus 9.3-fold), IL-8 (4.9- versus 8.6-fold), and IFN-γ (5- versus 9.5-fold). Antifoam activated complement and was avoided. PTF1+2 was generated in whole blood but not in plasma. In summary, air bubbles activated complement and triggered a C3-driven thromboinflammation. C3 inhibition reduced all mediators, whereas C5 inhibition reduced only TF-mRNA. Combined C5 and CD14 inhibition reduced IL-1β release. These data have implications for future mechanistic studies and possible pharmacological interventions in patients with air embolism.

A Conformational Change of Complement C5 Is Required for Thrombin-Mediated Cleavage, Revealed by a Novel Ex Vivo Human Whole Blood Model Preserving Full Thrombin Activity

Thrombin activation of C5 connects thrombosis to inflammation. Complement research in whole blood ex vivo necessitates anticoagulation, which potentially interferes with the inflammatory modulation by thrombin. We challenged the concept of thrombin as an activator of native C5 by analyzing complement activation and C5 cleavage in human whole blood anticoagulated with Gly-Pro-Arg-Pro (GPRP), a peptide targeting fibrin polymerization downstream of thrombin, allowing complete endogenous thrombin generation. GPRP dose-dependently inhibited coagulation but allowed for platelet activation in accordance with thrombin generation. Spontaneous and bacterial-induced complement activation by Escherichia coli and Staphylococcus aureus, analyzed at the level of C3 and C5, were similar in blood anticoagulated with GPRP and the thrombin inhibitor lepirudin. In the GPRP model, endogenous thrombin, even at supra-physiologic concentrations, did not cleave native C5, despite efficiently cleaving commercially sourced purified C5 protein, both in buffer and when added to C5-deficient serum. In normal serum, only exogenously added, commercially sourced C5 was cleaved, whereas the native plasma C5 remained intact. Crucially, affinity-purified C5, eluted under mild conditions using an MgCl2 solution, was not cleaved by thrombin. Acidification of plasma to pH ≤ 6.8 by hydrochloric or lactic acid induced a C5 antigenic change, nonreversible by pH neutralization, that permitted cleavage by thrombin. Circular dichroism on purified C5 confirmed the structural change during acidification. Thus, we propose that pH-induced conformational change allows thrombin-mediated cleavage of C5 and that, contrary to previous reports, thrombin does not cleave plasma C5 in its native form, suggesting that thrombin cleavage of C5 may be restricted to certain pathophysiological conditions.

Key role of the number of complement receptor 1 on erythrocytes for binding of Escherichia coli to erythrocytes and for leukocyte phagocytosis and oxidative burst in human whole blood

AIM

To study the role of complement receptor 1 (CR1) for binding of Escherichia coli (E. coli) to erythrocytes, for leukocyte phagocytosis, oxidative burst and complement activation in human whole blood from a CR1 deficient (CR1D) patient and healthy controls with low, medium and high CR1 numbers.

METHODS

Alexa-labelled bacteria were used to quantify erythrocyte-bound bacteria, free bacteria in plasma and phagocytosis using flow cytometry. Complement activation in plasma was measured by enzyme-linked immunosorbent assay. The CR1 numbers as well as C3bc and C4bc deposition on erythrocytes were measured by flow cytometry. Cytokines were measured using multiplex technology, and bacterial growth was measured by colony forming units. CR1 was blocked using the anti-CR1 blocking mAb 3D9.

RESULTS

Approximately 85% of E. coli bound to erythrocytes after 15 min incubation in donor blood with high and medium CR1 numbers, 50% in the person with low CR1 numbers and virtually no detectable binding in the CR1D (r² = 0.87, P < 0.0007). The number of free bacteria in plasma was inversely related to erythrocyte CR1 numbers (r² = 0.98, P < 0.0001). E. coli-induced phagocytosis and oxidative burst were significantly enhanced by the anti-CR1 mAb 3D9 and in the CR1D and the donor with low CR1 numbers. E. coli-induced complement activation in plasma, C3bc and C4bc deposition on erythrocytes, and bacterial growth were similar in all four cases.

CONCLUSIONS

CR1D and low CR1 numbers prevented E. coli binding to erythrocytes, increased free bacteria in plasma, phagocytosis and oxidative burst, but did not affect plasma or surface complement activation and bacterial growth.

Cholesterol Crystals Induce Coagulation Activation through Complement-Dependent Expression of Monocytic Tissue Factor

Cholesterol crystals (CC) are strong activators of complement and could potentially be involved in thromboinflammation through complement-coagulation cross-talk. To explore the coagulation-inducing potential of CC, we performed studies in lepirudin-based human whole blood and plasma models. In addition, immunohistological examinations of brain thrombi and vulnerable plaque material from patients with advanced carotid atherosclerosis were performed using polarization filter reflected light microscopy to identify CC. In whole blood, CC exposure induced a time- and concentration-dependent generation of prothrombin fragment 1+2 (PTF1.2), tissue factor (TF) mRNA synthesis, and monocyte TF expression. Blocking Abs against TF abolished CC-mediated coagulation, thus indicating involvement of the TF-dependent pathway. Blockade of FXII by corn trypsin inhibitor had a significant inhibitory effect on CC-induced PTF1.2 in platelet-free plasma, although the overall activation potential was low. CC exposure did not induce platelet aggregation, TF microparticle induction, or TF on granulocytes or eosinophils. Inhibition of complement C3 by CP40 (compstatin), C5 by eculizumab, or C5aR1 by PMX53 blocked CC-induced PTF1.2 by 90% and reduced TF⁺ monocytes from 18-20 to 1-2%. The physiologic relevance was supported by birefringent CC structures adjacent to monocytes (CD14), TF, and activated complement iC3b and C5b-9 in a human brain thrombus. Furthermore, monocyte influx and TF induction in close proximity to CC-rich regions with activated complement were found in a vulnerable plaque. In conclusion, CC could be active, releasable contributors to thrombosis by inducing monocyte TF secondary to complement C5aR1 signaling.

Staphylococcus aureus-induced complement activation promotes tissue factor-mediated coagulation

Essentials Complement, Toll-like receptors and coagulation cross-talk in the process of thromboinflammation. This is explored in a unique human whole-blood model of S. aureus bacteremia. Coagulation is here shown as a downstream event of C5a-induced tissue factor (TF) production. Combined inhibition of C5 and CD14 efficiently attenuated TF and coagulation.

SUMMARY

Background There is extensive cross-talk between the complement system, the Toll-like receptors (TLRs), and hemostasis. Consumptive coagulopathy is a hallmark of sepsis, and is often mediated through increased tissue factor (TF) expression. Objectives To study the relative roles of complement, TLRs and TF in Staphylococcus aureus-induced coagulation. Methods Lepirudin-anticoagulated human whole blood was incubated with the three S. aureus strains Cowan, Wood, and Newman. C3 was inhibited with compstatin, C5 with eculizumab, C5a receptor 1 (C5aR1) and activated factor XII with peptide inhibitors, CD14, TLR2 and TF with neutralizing antibodies, and TLR4 with eritoran. Complement activation was measured by ELISA. Coagulation was measured according to prothrombin fragment 1 + 2 (PTF1 + 2 ) determined with ELISA, and TF mRNA, monocyte surface expression and functional activity were measured with quantitative PCR, flow cytometry, and ELISA, respectively. Results All three strains generated substantial and statistically significant amounts of C5a, terminal complement complex, PTF1 + 2 , and TF mRNA, and showed substantial TF surface expression on monocytes and TF functional activity. Inhibition of C5 cleavage most efficiently and significantly inhibited all six markers in strains Cowan and Wood, and five markers in Newman. The effect of complement inhibition was shown to be completely dependent on C5aR1. The C5 blocking effect was equally potentiated when combined with blocking of CD14 or TLR2, but not TLR4. TF blocking significantly reduced PTF1 + 2 levels to baseline levels. Conclusions S. aureus-induced coagulation in human whole blood was mainly attributable to C5a-induced mRNA upregulation, monocyte TF expression, and plasma TF activity, thus underscoring complement as a key player in S. aureus-induced coagulation.

Granulocyte and monocyte CD11b expression during plasma separation is dependent on complement factor 5 (C5) - an ex vivo study with blood from a C5-deficient individual

The aim of the study was to investigate the role of complement factor 5 (C5) in reactions elicited by plasma separation using blood from a C5-deficient (C5D) individual, comparing it to C5-deficient blood reconstituted with C5 (C5DR) and blood from healthy donors. Blood was circulated through an ex vivo plasma separation model. Leukocyte CD11b expression and leukocyte-platelet conjugates were measured by flow cytometry during a 30-min period. Other markers were assessed during a 240-min period. Granulocyte and monocyte CD11b expression did not increase in C5D blood during plasma separation. In C5DR samples granulocytes CD11b expression, measured by mean fluorescence intensity (MFI), increased from 10481 ± 6022 (SD) to 62703 ± 4936, and monocytes CD11b expression changed from 13837 ± 7047 to 40063 ± 713. Granulocyte-platelet conjugates showed a 2.5-fold increase in the C5DR sample compared to the C5D sample. Monocyte-platelet conjugates increased independently of C5. In the C5D samples, platelet count decreased from 210 × 10⁹ /L (201-219) (median and range) to 51 × 10⁹ /L (50-51), and C3bc increased from 14 CAU/mL (21-7) to 198 CAU/mL (127-269), whereas TCC formation was blocked during plasma separation. In conclusion, up-regulation of granulocyte and monocyte CD11b during plasma separation was C5-dependent. The results also indicate C5 dependency in granulocyte-platelet conjugates formation.

Alginate microbeads are coagulation compatible, while alginate microcapsules activate coagulation secondary to complement or directly through FXII

Alginate microspheres are presently under evaluation for future cell-based therapy. Their ability to induce harmful host reactions needs to be identified for developing the most suitable devices and efficient prevention strategies. We used a lepirudin based human whole blood model to investigate the coagulation potentials of alginate-based microspheres: alginate microbeads (Ca/Ba Beads), alginate poly-l-lysine microcapsules (APA and AP microcapsules) and sodium alginate-sodium cellulose sulfate-poly(methylene-co-cyanoguanidine) microcapsules (PMCG microcapsules). Coagulation activation measured by prothrombin fragments 1+2 (PTF1.2) was rapidly and markedly induced by the PMCG microcapsules, delayed and lower induced by the APA and AP microcapsules, and not induced by the Ca/Ba Beads. Monocytes tissue factor (TF) expression was similarly activated by the microcapsules, whereas not by the Ca/Ba Beads. PMCG microcapsules-induced PTF1.2 was abolished by FXII inhibition (corn trypsin inhibitor), thus pointing to activation through the contact pathway. PTF1.2 induced by the AP and APA microcapsules was inhibited by anti-TF antibody, pointing to a TF driven coagulation. The TF induced coagulation was inhibited by the complement inhibitors compstatin (C3 inhibition) and eculizumab (C5 inhibition), revealing a complement-coagulation cross-talk. This is the first study on the coagulation potentials of alginate microspheres, and identifies differences in activation potential, pathways and possible intervention points.

STATEMENT OF SIGNIFICANCE

Alginate microcapsules are prospective candidate materials for cell encapsulation therapy. The material surface must be free of host cell adhesion to ensure free diffusion of nutrition and oxygen to the encapsulated cells. Coagulation activation is one gateway to cellular overgrowth through deposition of fibrin. Herein we used a physiologically relevant whole blood model to investigate the coagulation potential of alginate microcapsules and microbeads. The coagulation potentials and the pathways of activation were depending on the surface properties of the materials. Activation of the complement system could also be involved, thus emphasizing a complement-coagulation cross-talk. Our findings points to complement and coagulation inhibition as intervention point for preventing host reactions, and enhance functional cell-encapsulation devices.

Effect of the anticoagulant, storage time and temperature of blood samples on the concentrations of 27 multiplex assayed cytokines - Consequences for defining reference values in healthy humans

Cytokines are potentially useful biomarkers of sepsis and other inflammatory conditions. Many cytokines can be released by leukocytes and platelets after sampling. The sampling and processing techniques are consequently critically important to measure the in vivo levels. We therefore examined the effects of four different anticoagulants, EDTA, citrate, lepirudin, heparin compared to serum, on the levels of 27 different cytokines. The effects of storage temperature, freezing and thawing on the plasma cytokines were examined. Cytokines were analysed using a multiplex immunoassay. The cytokine levels in serum were significantly higher compared with plasma, consistent with release of cytokines in vitro during coagulation. In general, the lowest values for all cytokines were found in EDTA samples, stored on crushed ice, centrifuged within 4h and thereafter stored at -80°C. MCP-1 and MIP-1β levels were highest in heparin plasma and storage of blood for up to 4h at room temperature significantly increased the interleukin (IL)-2, IL-6, IL-8, IFN-γ and GM-CSF levels in EDTA plasma, indicating post-sampling release. In contrast, the IP-10 levels were unaffected by sample storage at both temperatures. Our results indicate that the cytokines were more stable in plasma than in whole blood after sampling. Thus, cytokines should be analysed in EDTA plasma samples stored on ice and centrifuged within 4h. Based on these data, the reference ranges of 27 cytokines in EDTA plasma in 162 healthy human donors were calculated.

Effects on muscle strength, maximal jump height, flexibility and postural sway after soccer and Zumba exercise among female hospital employees: a 9-month randomised controlled trial

This 9-month randomised controlled workplace physical activity trial investigated the effects of soccer and Zumba exercise, respectively, on muscle strength, maximal jump height, sit-and-reach flexibility and postural sway among female workers. A total of 107 female hospital employees aged 25-63 were cluster-randomised to a soccer group, a Zumba group or a control group. Training was conducted outside working hours as two to three 1-h weekly sessions the first 3 months and once a week the last 6 months. Tests were conducted at baseline, after 3 and 9 months. The soccer group improved maximal neck extension strength both after 3 (1.2 kg; P < 0.05) and 9 months (1.7 kg; P < 0.01) compared to the control group. The Zumba group improved maximal trunk extension strength (3.1 kg; P = 0.04) after 3 months, with improvements in postural sway velocity moment (-9.2 mm(2)/s; P < 0.05) and lower limb lean mass (0.4 kg; P < 0.05) after 9 months. No significant intervention effects were revealed in vertical jump height or sit-and-reach flexibility. The present study indicates that workplace-initiated soccer and Zumba exercise may be beneficial for improvement of the neck and trunk strength, which may have preventive effects with regard to future perceived muscle pain in the respective body regions. Furthermore, the Zumba group revealed positive effects on lower limb lean mass and postural sway compared to the control group.

Combined inhibition of complement and CD14 improved outcome in porcine polymicrobial sepsis

Introduction

Sepsis is an exaggerated and dysfunctional immune response to infection. Activation of innate immunity recognition systems including complement and the Toll-like receptor family initiate this disproportionate inflammatory response. The aim of this study was to explore the effect of combined inhibition of the complement component C5 and the Toll-like receptor co-factor CD14 on survival, hemodynamic parameters and systemic inflammation including complement activation in a clinically relevant porcine model of polymicrobial sepsis.

Methods

Norwegian landrace piglets (4 ± 0.5 kg) were blindly randomized to a treatment group (n = 12) receiving the C5 inhibitor coversin (OmCI) and anti-CD14 or to a positive control group (n = 12) receiving saline. Under anesthesia, sepsis was induced by a 2 cm cecal incision and the piglets were monitored in standard intensive care for 8 hours. Three sham piglets had a laparotomy without cecal incision or treatment. Complement activation was measured as sC5b-9 using enzyme immunoassay. Cytokines were measured with multiplex technology.

Results

Combined C5 and CD14 inhibition significantly improved survival (p = 0.03). Nine piglets survived in the treatment group and four in the control group. The treatment group had significantly lower pulmonary artery pressure (p = 0.04) and ratio of pulmonary artery pressure to systemic artery pressure (p < 0.001). Plasma sC5b-9 levels were significantly lower in the treatment group (p < 0.001) and correlated significantly with mortality (p = 0.006). IL-8 and IL-10 were significantly (p < 0.05) lower in the treatment group.

Conclusions

Combined inhibition of C5 and CD14 significantly improved survival, hemodynamic parameters and inflammation in a blinded, randomized trial of porcine polymicrobial sepsis.

The key roles of complement and tissue factor in Escherichia coli-induced coagulation in human whole blood

The complement system and the Toll-like (TLR) co-receptor CD14 play important roles in innate immunity and sepsis. Tissue factor (TF) is a key initiating component in intravascular coagulation in sepsis, and long pentraxin 3 (PTX3) enhances the lipopolysaccharide (LPS)-induced transcription of TF. The aim of this study was to study the mechanism by which complement and CD14 affects LPS- and Escherichia coli (E. coli)-induced coagulation in human blood. Fresh whole blood was anti-coagulated with lepirudin, and incubated with ultra-purified LPS (100 ng/ml) or with E. coli (1 × 10(7) /ml). Inhibitors and controls included the C3 blocking peptide compstatin, an anti-CD14 F(ab')2 antibody and a control F(ab')2 . TF mRNA was measured using quantitative polymerase chain reaction (qPCR) and monocyte TF surface expression by flow cytometry. TF functional activity in plasma microparticles was measured using an amidolytic assay. Prothrombin fragment F 1+2 (PTF1.2) and PTX3 were measured by enzyme-linked immunosorbent assay (ELISA). The effect of TF was examined using an anti-TF blocking antibody. E. coli increased plasma PTF1.2 and PTX3 levels markedly. This increase was reduced by 84->99% with compstatin, 55-97% with anti-CD14 and > 99% with combined inhibition (P < 0·05 for all). The combined inhibition was significantly (P < 0·05) more efficient than compstatin and anti-CD14 alone. The LPS- and E. coli-induced TF mRNA levels, monocyte TF surface expression and TF functional activity were reduced by > 99% (P < 0·05) with combined C3 and CD14 inhibition. LPS- and E. coli-induced PTF1.2 was reduced by 76-81% (P < 0·05) with anti-TF antibody. LPS and E. coli activated the coagulation system by a complement- and CD14-dependent up-regulation of TF, leading subsequently to prothrombin activation.

Gene expression profiling of Gram-negative bacteria-induced inflammation in human whole blood: The role of complement and CD14-mediated innate immune response

Non-sterile pathogen-induced sepsis and sterile inflammation like in trauma or ischemia–reperfusion injury may both coincide with the life threatening systemic inflammatory response syndrome and multi-organ failure. Consequently, there is an urgent need for specific biomarkers in order to distinguish sepsis from sterile conditions. The overall aim of this study was to uncover putative sepsis biomarkers and biomarker pathways, as well as to test the efficacy of combined inhibition of innate immunity key players complement and Toll-like receptor co-receptor CD14 as a possible therapeutic regimen for sepsis. We performed whole blood gene expression analyses using microarray in order to profile Gram-negative bacteria-induced inflammatory responses in an ex vivo human whole blood model. The experiments were performed in the presence or absence of inhibitors of complement proteins (C3 and CD88 (C5a receptor 1)) and CD14, alone or in combination. In addition, we used blood from a C5-deficient donor. Anti-coagulated whole blood was challenged with heat-inactivated Escherichia coli for 2 h, total RNA was isolated and microarray analyses were performed on the Affymetrix GeneChip Gene 1.0 ST Array platform. The initial experiments were performed in duplicates using blood from two healthy donors. C5-deficiency is very rare, and only one donor could be recruited. In order to increase statistical power, a technical replicate of the C5-deficient samples was run. Subsequently, log₂-transformed intensities were processed by robust multichip analysis and filtered using a threshold of four. In total, 73 microarray chips were run and analyzed. The normalized and filtered raw data have been deposited in NCBI's Gene Expression Omnibus (GEO) and are accessible with GEO Series accession number GSE55537. Linear models for microarray data were applied to estimate fold changes between data sets and the respective multiple testing adjusted p-values (FDR q-values). The interpretation of the data has been published by Lau et al. in an open access article entitled “CD14 and Complement Crosstalk and Largely Mediate the Transcriptional Response to Escherichia coli in Human Whole Blood as revealed by DNA Microarray” (Lau et al., 2015).

CD14 and complement crosstalk and largely mediate the transcriptional response to Escherichia coli in human whole blood as revealed by DNA microarray

Systemic inflammation like in sepsis is still lacking specific diagnostic markers and effective therapeutics. The first line of defense against intruding pathogens and endogenous damage signals is pattern recognition by e.g., complement and Toll-like receptors (TLR). Combined inhibition of a key complement component (C3 and C5) and TLR-co-receptor CD14 has been shown to attenuate certain systemic inflammatory responses. Using DNA microarray and gene annotation analyses, we aimed to decipher the effect of combined inhibition of C3 and CD14 on the transcriptional response to bacterial challenge in human whole blood. Importantly, combined inhibition reversed the transcriptional changes of 70% of the 2335 genes which significantly responded to heat-inactivated Escherichia coli by on average 80%. Single inhibition was less efficient (p<0.001) but revealed a suppressive effect of C3 on 21% of the responding genes which was partially counteracted by CD14. Furthermore, CD14 dependency of the Escherichia coli-induced response was increased in C5-deficient compared to C5-sufficient blood. The observed crucial distinct and synergistic roles for complement and CD14 on the transcriptional level correspond to their broad impact on the inflammatory response in human blood, and their combined inhibition may become inevitable in the early treatment of acute systemic inflammation.

Cholesterol crystals induce complement-dependent inflammasome activation and cytokine release

Inflammation is associated with development of atherosclerosis, and cholesterol crystals (CC) have long been recognized as a hallmark of atherosclerotic lesions. CC appear early in the atheroma development and trigger inflammation by NLRP3 inflammasome activation. In this study we hypothesized whether CC employ the complement system to activate inflammasome/caspase-1, leading to release of mature IL-1β, and whether complement activation regulates CC-induced cytokine production. In this study we describe that CC activated both the classical and alternative complement pathways, and C1q was found to be crucial for the activation. CC employed C5a in the release of a number of cytokines in whole blood, including IL-1β and TNF. CC induced minimal amounts of cytokines in C5-deficient whole blood, until reconstituted with C5. Furthermore, C5a and TNF in combination acted as a potent primer for CC-induced IL-1β release by increasing IL-1β transcripts. CC-induced complement activation resulted in upregulation of complement receptor 3 (CD11b/CD18), leading to phagocytosis of CC. Also, CC mounted a complement-dependent production of reactive oxygen species and active caspase-1. We conclude that CC employ the complement system to induce cytokines and activate the inflammasome/caspase-1 by regulating several cellular responses in human monocytes. In light of this, complement inhibition might be an interesting therapeutic approach for treatment of atherosclerosis.

Chimeric anti-CD14 IGG2/4 Hybrid antibodies for therapeutic intervention in pig and human models of inflammation

CD14 is a key recognition molecule of innate immune responses, interacting with several TLRs. TLR signaling cross-talks extensively with the complement system, and combined CD14 and complement inhibition has been proved effective in attenuating inflammatory responses. Pig models of human diseases have emerged as valuable tools to study therapeutic intervention, but suitable neutralizing Abs are rare. Undesired Fc-mediated functions, such as platelet activation and IL-8 release induced by the porcine CD14-specific clone Mil2, limit further studies. Therefore, an inert human IgG2/IgG4 hybrid C region was chosen for an rMil2. As revealed in ex vivo and in vivo pig experiments, rMil2 inhibited the CD14-mediated proinflammatory cytokine response similar to the original clone, but lacked the undesired Fc-effects, and inflammation was attenuated further by simultaneous complement inhibition. Moreover, rMil2 bound porcine FcRn, a regulator of t1/2 and biodistribution. Thus, rMil2, particularly combined with complement inhibitors, should be well suited for in vivo studies using porcine models of diseases, such as sepsis and ischemia-reperfusion injury. Similarly, the recombinant anti-human CD14 IgG2/4 Ab, r18D11, was generated with greatly reduced Fc-mediated effects and preserved inhibitory function ex vivo. Such Abs might be drug candidates for the treatment of innate immunity-mediated human diseases.

Bride and groom in systemic inflammation--the bells ring for complement and Toll in cooperation

Attenuating the sepsis-induced systemic inflammatory response, with subsequent homeostatic imbalance, has for years been one of the main tasks in sepsis related research. Complement and the TLR family constitute two important upstream sensor and effector-systems of innate immunity. Although they act as partly independent branches of pattern recognition, recent evidence indicate a considerable cross-talk implying that they can either compensate, synergize or antagonize each other. Combined inhibition of these pathways is therefore a particularly interesting approach with a profound anti-inflammatory potential. In previous preclinical studies, we demonstrated that targeting the key molecules C3 or C5 of complement and CD14 of the TLR family had a vast anti-inflammatory effect on Gram-negative bacteria-induced inflammation and sepsis. In this review, we elucidate the significance of these key molecules as important targets for intervention in sepsis and systemic inflammatory response syndrome. Finally, we argue that a combined inhibition of complement and CD14 represent a potential general treatment regimen, beyond the limit of sepsis, including non-infectious systemic inflammation and ischemia reperfusion injury.

The effects of selective complement and CD14 inhibition on the E. coli-induced tissue factor mRNA upregulation, monocyte tissue factor expression, and tissue factor functional activity in human whole blood

BACKGROUND

The complement pathway and CD14 play essential roles in inflammation, but little is known about the relative roles of complement and CD14 in E. coli-induced tissue factor (TF) mRNA upregulation, expression by monocytes, and functional activity in human whole blood.

METHODS

Whole E. coli bacteria were incubated for up to 4 h in human whole blood containing the anticoagulant lepirudin, which does not affect complement activation. TF mRNA levels were analyzed using reverse transcription, quantitative real-time PCR (RT-qPCR), and the expression of TF on the cell surface was analyzed using flow cytometry. Complement was selectively inhibited using the C3 convertase inhibitor compstatin or a C5a receptor antagonist (C5aRa), while CD14 was blocked by an anti-CD14 F(ab')2 monoclonal antibody.

RESULTS

The E. coli-induced TF mRNA upregulation was reduced to virtually background levels by compstatin, whereas anti-CD14 had no effect. Monocyte TF expression and TF activity in plasma microparticles were significantly reduced by C5aRa. Anti-CD14 alone only slightly reduced E. coli-induced monocyte TF expression but showed a modest additive effect when combined with the complement inhibitors. Inhibiting complement and CD14 efficiently reduced the expression of the E. coli-induced cytokines IL-1beta, IL-6, IL-8, and platelet-derived growth factor bb.

CONCLUSION

Our results indicate that E. coli-induced TF mRNA upregulation is mainly dependent on complement activation, while CDI4 plays a modest role in monocyte TF expression and the plasma TF activity in human whole blood.

Differential effect of inhibiting MD-2 and CD14 on LPS- versus whole E. coli bacteria-induced cytokine responses in human blood

BACKGROUND

Sepsis is a major world-wide medical problem with high morbidity and mortality. Gram-negative bacteria are among the most important pathogens of sepsis and their LPS content is regarded to be important for the systemic inflammatory reaction. The CD14/myeloid differentiation factor 2 (MD-2)/TLR4 complex plays a major role in the immune response to LPS . The aim of this study was to compare the effects of inhibiting MD-2 and CD14 on ultra-pure LPS - versus whole E. coli bacteria-induced responses.

METHODS

Fresh human whole blood was incubated with upLPS or whole E. coli bacteria in the presence of MD-2 or CD14 neutralizing monoclonal antibodies, or their respective controls, and/or the specific complement-inhibitor compstatin. Cytokines were measured by a multiplex (n = 27) assay. NFκB activity was examined in cells transfected with CD14, MD-2 and/or Toll-like receptors.

RESULTS

LPS-induced cytokine response was efficiently and equally abolished by MD-2 and CD14 neutralization. In contrast, the response induced by whole E. coli bacteria was only modestly reduced by MD-2 neutralization, whereas CD14 neutralization was more efficient. Combination with compstatin enhanced the effect of MD-2 neutralization slightly. When compstatin was combined with CD14 neutralization, however, the response was virtually abolished for all cytokines, including IL-17, which was only inhibited by this combination. The MD-2-independent effect observed for CD14 could not be explained by TLR2 signaling.

CONCLUSION

Inhibition of CD14 is more efficient than inhibition of MD-2 on whole E. coli-induced cytokine response, suggesting CD14 to be a better target for intervention in Gram-negative sepsis, in particular when combined with complement inhibition.

Neisseria meningitidis and Escherichia coli are protected from leukocyte phagocytosis by binding to erythrocyte complement receptor 1 in human blood

The initial interaction of Gram-negative bacteria with erythrocytes and its implications on leukocyte phagocytosis and oxidative burst in human whole blood were examined. Alexa-labeled Escherichia coli, wild-type H44/76 N. meningitidis and the H44/76lpxA lipopolysaccharide (LPS)-deficient mutant were incubated with whole blood using lepirudin as anticoagulant which has no adverse effects on complement. Bacteria free in plasma, bound to erythrocytes or phagocytized by granulocytes and monocytes were quantified using flow cytometry. The effects of the C3 inhibitor compstatin, a C5a receptor antagonist (C5aRa) and a complement receptor 1 (CR1)-blocking antibody (3D9) were examined. Most bacteria (80%) immediately bound to erythrocytes. The binding gradually declined over time, with a parallel increase in phagocytosis. Complement inhibition with compstatin reduced erythrocyte binding and bacterial C3 opsonization. In contrast, the C5aRa efficiently reduced phagocytosis, but did not affect the binding of bacteria to erythrocytes. The anti-CR1 blocking mAb dose-dependently reduced bacterial binding to erythrocytes to nil, with subsequent increased phagocytosis and oxidative burst. LPS had no effect on these processes since similar results were obtained using an LPS-deficient N. meningitidis mutant. In vivo experiments in a pig model of sepsis showed limited binding of bacteria to erythrocytes, consistent with the facts that erythrocyte CR1 receptors are absent in non-primates and that the bacteria were mainly found in the lungs. In conclusion, complement-dependent binding of Gram-negative bacteria to erythrocyte CR1 decreases phagocytosis and oxidative burst by leukocytes in human whole blood.

Selective inhibition of TNF-alpha or IL-1 beta does not affect E. coli-induced inflammation in human whole blood

Inhibition of the inappropriate and excessive inflammatory response has been a main issue in sepsis-related research. Historically, TNF-alpha and IL-1 beta have been postulated as key mediators in sepsis, but selective inhibition of these cytokines has failed in clinical trials. Recently it was found that inhibition of upstream recognition by complement and CD14 could efficiently reduce Escherichia coli (E. coli)-induced inflammation. An ex vivo model with lepirudin-anticoagulated human whole blood was used to explore the significance of selective inhibition of TNF-alpha and IL-1 beta in E. coli-induced inflammation. The effect of TNF-alpha, IL-1 beta, complement and CD14 on the inflammatory response was assessed by adding highly specific neutralizing agents to these mediators. Proinflammatory cytokines, expression of CD11b and oxidative burst were measured. The controls included relevant isotype-matched immunoglobulins and peptides. Selective inhibition of TNF-alpha or IL-1 beta had no impact on E. coli-induced release of proinflammatory cytokines, CD11b-upregulation or oxidative burst. In contrast, the combined inhibition of complement and CD14 virtually abolished these responses. These data suggest that both TNF-alpha and IL-1 beta are downstream mediators and as single mediators play a limited role within the complex inflammatory reactions induced by E. coli.

Combined inhibition of complement and CD14 abolish E. coli-induced cytokine-, chemokine- and growth factor-synthesis in human whole blood

The relative role of complement and CD14 in E. coli-induced cytokine synthesis in an in vitro human whole blood model of sepsis was examined. Fresh lepirudin-anticoagulated whole blood was incubated with E. coli for 2h. Monoclonal antibodies or a C5a receptor antagonist were used to block complement. Inflammatory mediators (n=27) were measured by multiplex technology, selected cytokine mRNA by real time PCR, and CD11b, oxidative burst and phagocytosis by flow cytometry. E. coli significantly increased 18 of the 27 inflammatory mediators, including proinflammatory cytokines (TNF-alpha, IL-6, INF-gamma and IL-1beta), chemokines (IL-8, MCP-1, MIP-1alpha, MIP-1beta, eotaxin and IP-10), growth factors (VEGF, FGF-basic, G-CSF and GM-CSF) and other interleukins (IL-9, IL-15 and IL-17). Notably, the increases in all mediators were abolished by a combined inhibition of CD14 and complement using anti-C2 and anti-factor D in combination, whereas the relative effect of the inhibition of complement and CD14 varied. In comparison, a C5a receptor antagonist and anti-CD14 in combination reduced cytokine synthesis less efficiently. Real time PCR analysis confirmed that the cytokine synthesis was blocked at the mRNA level. Similarly, E. coli-induced CD11b up-regulation, oxidative burst and phagocytosis was totally inhibited by CD14, anti-C2 and anti-factor D in combination after 2h incubation. In conclusion, the combined inhibition of complement using anti-C2, anti-factor D and CD14 almost completely inhibits the E. coli-induced inflammatory response. The combined approach may therefore be a new treatment regimen in Gram-negative sepsis.

Hypothesis: combined inhibition of complement and CD14 as treatment regimen to attenuate the inflammatory response

Pattern recognition is an essential event in innate immunity. Complement and Toll-like receptors (TLR), including the CD14 molecule, are two important upstream components of the innate immune system, recognizing exogenous structures as well as endogenous ligands. They act partly independent in the inflammatory network, but also have several cross-talk mechanisms which are under current investigation. Complement is an essential part of innate immunity protecting the host against infection. However, it is a double-edged sword since inappropriate activation may damage the host. Uncontrolled systemic activation of complement, as seen in severe sepsis, may contribute to the breakdown of homeostatic mechanisms leading to the irreversible state of septic shock. Complement inhibition is promising for protection of lethal experimental sepsis, but clinical studies are missing. Lipopolysaccharide (LPS) has been implicated in the pathogenesis of gram-negative sepsis by inducing synthesis of pro-inflammatory cytokines through binding to CD14 and the TLR4/MD-2 complex. Neutralization of LPS or blocking of CD14 has been effective in preventing LPS-induced lethal shock in animal studies, but results from clinical studies have been disappointing, as for most other therapeutic strategies. Based on some recently published data and further pilot data obtained in our laboratory, we hypothesize that inhibition of complement combined with neutralization of CD14 may attenuate the uncontrolled inflammatory reaction which leads to breakdown of homeostasis during sepsis. We further postulate this regimen as an approach for efficient inhibition of the initial innate recognition, exogenous as well as endogenous, to prevent downstream activation of the inflammatory reaction in general.

The role of complement C3 opsonization, C5a receptor, and CD14 in E. coli-induced up-regulation of granulocyte and monocyte CD11b/CD18 (CR3), phagocytosis, and oxidative burst in human whole blood

The relative role of complement and CD14 in Escherichia coli-induced leukocyte CD11b up-regulation, phagocytosis, and oxidative burst in human whole blood was examined. The highly specific thrombin inhibitor lepirudin was used as anticoagulant, as it does not affect complement activation. Complement inhibition at the level of C3 (anti-C2 and anti-factor D) and C5 (C5a receptor antagonist and anti-C5/C5a) efficiently inhibited CD11b up-regulation, phagocytosis, and oxidative burst in granulocytes. Monocyte activation was generally less complement-dependent, but when C3 activation was blocked, a pronounced inhibition of phagocytosis and oxidative burst was obtained. Only the combination of anti-C2 and antifactor D blocked E. coli C3 opsonization completely. Whole E. coli, disrupted E. coli, and the C3-convertase activator cobra venom factor up-regulated CD11b rapidly on both cell types, proportional to their complement activation potential in the fluid phase. In comparison, purified LPS at concentrations comparable with that present in the E. coli preparations did not activate complement. Oxidative burst was induced only by whole bacteria. Finally, the combination of complement inhibition and anti-CD14 completely blocked E. coli-induced granulocyte and monocyte CD11b up-regulation and quantitatively, virtually abolished phagocytosis. The results indicate that complement and CD14, despite differential effects on granulocytes and monocytes, are the two crucial, quantitative factors responsible for E. coli-induced CD11b, phagocytosis, and oxidative burst in both cell types.

Differential Effect of Heparin Coating and Complement Inhibition on Artificial Surface-Induced Eicosanoid Production

BACKGROUND

Contact between blood and artificial surfaces induces an inflammatory response including activation of leukocytes and platelets, as well as complement and other plasma cascade systems. In the present study we investigated the roles of complement and surface modification in polyvinyl chloride-induced synthesis of eicosanoids (arachidonic acid metabolites).

METHODS

Human whole blood was incubated in rotating loops of polyvinyl chloride or heparin-coated polyvinyl chloride tubing for 4 hours. Plasma concentrations of the eicosanoids leukotriene B4, prostaglandin E2 and thromboxane B2 were quantified.

RESULTS

Polyvinyl chloride induced a substantial increase in leukotriene B4, prostaglandin E2, and thromboxane B2. Inhibition of complement activation by the complement factor 3 binding peptide compstatin or blockade of the complement factor 5a receptor with a specific antagonist significantly and specifically inhibited the synthesis of leukotriene B4, whereas thromboxane B2 and prostaglandin E2 synthesis were apparently complement independent. The increase in all three mediators was significantly reduced by the heparin coating. Indomethacin abolished the increase of the cyclooxygenase products prostaglandin E2 and thromboxane B2, but had no effect on the increase of the lipoxygenase product leukotriene B4, consistent with the specificity of indomethacin for the cyclooxygenase and confirming the specificity of complement inhibition.

CONCLUSIONS

Polyvinyl chloride-induced increase in all three eicosanoids was attenuated by heparin coating, whereas complement inhibition selectively reduced the synthesis of leukotriene B4.

Brain Magnetic Resonance Imaging White-Matter Lesions and Cerebrospinal Fluid Findings in Patients with Acute Intermittent Porphyria

BACKGROUND

Case reports display similarities between multiple sclerosis and acute intermittent porphyria (AIP). This study examines whether patients with AIP in general demonstrate white-matter lesions on brain magnetic resonance imaging (MRI) and/or abnormalities in plasma and/or cerebrospinal fluid (CSF) when examined outside attacks. We looked particularly for the presence of oligoclonal bands (OB) of immunoglobulin (Ig) in liquor.

METHODS

Eight AIP gene carriers without previous episodes of porphyria, mean age 42.8 years (range 30-60), and 8 AIP gene carriers with previous episodes of porphyria, mean age 42.8 years (range 33-62), were examined with brain MRI, venous blood samples and lumbar punctures.

RESULTS

Two male AIP gene carriers with previous episodes of porphyria, 58 and 35 years of age, had multiple white-matter, high-signal lesions on T(2)- weighted MRI sequences. Two AIP gene carriers without previous episodes of porphyria, 1 male and 1 female, had less than 5 such lesions. No OB were seen in the CSF in any patient, but 1 carrier had an increased level of protein in the CSF. Seven of 16 subjects (44%) had increased levels of HbA1c (>6.0), suggesting protracted hyperglycemia, and 3 further subjects had borderline levels (5.9).

CONCLUSION

T(2)-weighted MRI sequences demonstrated multiple white-matter, high-signal lesions in 4 out of 16 AIP gene carriers (25%). No carrier demonstrated OB of Ig in CSF, making it unlikely that demyelinating lesions play a pivotal role in the pathogenesis of CNS symptoms in AIP. Only 1 AIP gene carrier had an increased level of protein in CSF; this contrasts with studies during acute attacks of porphyria. Seven subjects (44%) had abnormally high levels of HbA1c, in spite of the fact that no patient had a previous diagnosis of diabetes mellitus.

Essential role of the C5a receptor in E coli-induced oxidative burst and phagocytosis revealed by a novel lepirudin-based human whole blood model of inflammation

Complement plays an essential role in inflammation and tissue damage. However, it is largely unknown to what extent the system acts as a primary inducer of secondary mediator systems in the inflammatory network of human whole blood. Here we describe a novel in vitro model using the thrombin-specific hirudin analog lepirudin as anticoagulant, which, in contrast to heparin, did not interfere with complement activation. The model was used to study the role of complement in Escherichia coli-induced inflammatory responses. Granulocyte and monocyte oxidative burst was complement dependent as it was reduced by 85% and 70%, respectively, by the C3 [corrected] binding peptide compstatin. A similar reduction was found by inhibition of C5, C5a, and C5a receptor (C5aR). Furthermore, anti-CR3 antibodies were as efficient as the C5aR antagonist in reducing granulocyte oxidative burst, whereas blocking CD14 or C3aR had no effect. Up-regulation of granulocyte CR3 was virtually abolished by a C5aR antagonist. Opsonization and phagocytosis was completely inhibited by blocking of C5aR or CR3, whereas blocking of the FcgammaRs (CD16, CD32, CD64) had no effect. In contrast to oxidative burst and phagocytosis, cytokine secretion was largely complement independent. Thus, anti-CD14 abolished tumor necrosis factor-alpha, interleukin-6 (IL-6), and IL-10 secretion, whereas IL-8 was equally inhibited by anti-CD14 and compstatin. In conclusion, the present model is particularly useful for studying complement as part of the inflammatory network. The results emphasize a crucial role for C5a-C5aR interaction in E coli-induced up-regulation of CR3 and the subsequent oxidative burst and phagocytosis. Complement inhibition may have therapeutic implications in oxidative burst-induced tissue damage.

[Acute intermittent porphyria]

BACKGROUND

Acute intermittent porphyria is an autosomal dominant disease caused by a mutation in the gene coding for the porphobilinogen deaminase enzyme in the haem biosynthesis. The prevalence varies geographically.

MATERIAL AND METHODS

This article presents a literature-based review of acute intermittent porphyria with emphasis on epidemiology and diagnostic and therapeutic strategies.

RESULTS

The 50% reduced activity of porphobilinogen deaminase enzyme found in heterozygote persons is sufficient for basal conditions, but during attacks, stimulation of haem synthesis upstream produces toxic spillover products that give a purple colour to the urine. Many causes: common drugs, alcohol, starvation, pregnancy or menstruation, can lead to attacks of abdominal pain, motor and/or sensory polyneuropathy autonomic dysfunction, hyponatraemia, mental changes and seizures. Hepatic carcinoma may develop in older patients with acute intermittent porphyria. Acute attacks are treated with glucose or haem arginate intravenously. Preliminary results indicate a prevalence of 600/100,000 for acute intermittent porphyria in the municipality of Saltdal in Norway compared to 1-2/100,000 in Europe generally. A W198X mutation is found in the porphobilinogen deaminase enzyme gene in members of a family in Saltdal, shared by some families in northern Sweden.

INTERPRETATION

The high prevalence of acute intermittent porphyria in specific geographic areas emphasizes the importance of correct diagnosis, the first crucial step in avoiding attacks and associated diseases.

Secretory and cytosolic phospholipase A(2)regulate the long-term cytokine-induced eicosanoid production in human keratinocytes

The involvement of cytosolic phospholipase A(2)(cPLA(2)) and secretory non-pancreatic PLA(2)(npPLA(2)) in release of arachidonic acid (AA) preceding eicosanoid formation in the human keratinocyte cell line HaCaT was examined. Interleukin 1beta (IL-1beta) and tumour necrosis factor-alpha (TNF), phorbol myristate acetate (PMA) and calcium ionophore A(23187)increased the extracellular AA release, and stimulated eicosanoid synthesis as determined by HPLC analysis. The main metabolites after stimulation with IL-1beta, PMA or A(23187)were PGE(2), an unidentified PG and LTB(4), while TNF stimulated HETE-production. Both cPLA(2)and npPLA(2)message and enzyme activity were detected in unstimulated HaCaT cells. IL-1beta, PMA and TNF increased both cPLA(2)enzyme activity and expression, but did not lead to any increase in npPLA(2)expression or activity. The selective npPLA(2)inhibitors LY311727 and 12-epi-scalaradial, or the cPLA(2)inhibitor arachidonyl trifluoro methyl ketone (AACOCF(3)) reduced IL-1beta-induced eicosanoid production in a concentration dependent manner. The results presented strongly suggest that both cPLA(2)and npPLA(2)contribute to the long-term generation of AA preceding eicosanoid production in differentiated, human keratinocytes. Inhibitors against npPLA2 or cPLA2 enzymes should be useful in treating inflammatory skin diseases, such as psoriasis.