Choice of immunoassay to evaluate porcine cytokine levels.

BACKGROUND: In order to adequately monitor cytokines in experimental models, currently available methods and commercially available kits should be compared. AIM: To compare the plasma and tissue concentrations of IL-1ß, IL-6, IL-8, IL-10, and TNF as a measure of systemic inflammation in septic pigs. METHODS: Cytokines were quantified from blood and tissue samples obtained at 0, 60, 120, 180, and 240 min, and in postmortem biopsies of the liver, kidney, lung, heart, and spleen from 26 anesthetized landrace pigs. (24 with experimental sepsis, two sham controls). Porcine-specific ELISAs (R&D) and multiplex (9-plex from Thermo Fischer, 13-plex from Millipore) immunoassays were compared. RESULTS: The assays differed for the different cytokines and between blood and tissue. In blood, the highest concentration of TNF and IL-6 was in ELISA, IL-1ß equal in ELISA and 13-plex, IL-8 in 13-plex and IL-10 in 9-plex. In tissue, the highest concentration of TNF and IL-1ß was in ELISA, IL-6 and IL-8 in 13-plex and IL-10 in 9-plex. CONCLUSION: The choice of analysis impacts the quantified cytokine responses in porcine models. ELISA and multiplex techniques supplement each other and our data suggest which assays to use for the quantification of the different cytokines.

Combined inhibition of C5 and CD14 efficiently attenuated the inflammatory response in a porcine model of meningococcal sepsis.

BACKGROUND: Fulminant meningococcal sepsis, characterized by overwhelming innate immune activation, mostly affects young people and causes high mortality. This study aimed to investigate the effect of targeting two key molecules of innate immunity, complement component C5, and co-receptor CD14 in the Toll-like receptor system, on the inflammatory response in meningococcal sepsis. METHODS: Meningococcal sepsis was simulated by continuous intravenous infusion of an escalating dose of heat-inactivated Neisseria meningitidis administered over 3 h. The piglets were randomized, blinded to the investigators, to a positive control group (n = 12) receiving saline and to an interventional group (n = 12) receiving a recombinant anti-CD14 monoclonal antibody together with the C5 inhibitor coversin. RESULTS: A substantial increase in plasma complement activation in the untreated group was completely abolished in the treatment group (p = 0.006). The following inflammatory mediators were substantially reduced in plasma in the treatment group: Interferon-γ by 75% (p = 0.0001), tumor necrosis factor by 50% (p = 0.01), Interleukin (IL)-8 by 50% (p = 0.03), IL-10 by 40% (p = 0.04), IL-12p40 by 50% (p = 0.03), and granulocyte CD11b (CR3) expression by 20% (p = 0.01). CONCLUSION: Inhibition of C5 and CD14 may be beneficial in attenuating the detrimental effects of complement activation and modulating the cytokine storm in patients with fulminant meningococcal sepsis.

Massive Organ Inflammation in Experimental and in Clinical Meningococcal Septic Shock.

Fulminant meningococcal sepsis is characterized by a massive growth of bacteria in the circulation, regarded as the primary inflammatory site, with no specific solid organ focus. Here we aimed to study the local inflammatory response in organs using a porcine model of fulminant meningococcal septic shock challenged with exponentially increasing doses of heat inactivated Neisseria meningitidis. The results were compared with those obtained in organs post mortem from three patients with lethal meningococcal septic shock. Nine patients with lethal pneumococcal disease and 14 patients with sudden infant death syndrome served as controls. Frozen tissue were thawed, homogenized and prepared for quantification of bacterial DNA by real-time polymerase chain reaction, and key inflammatory mediators were measured by ELISA in the pig material and by multiplex in the human material. In addition, gene expression assayed by Affymetrix gene expression profiling was performed in the pig study. The porcine model revealed a major influx of N. meningitidis in lungs, liver, spleen, and kidneys accompanied with major production of cardinal inflammatory mediators including tumor necrosis factor, interleukin (IL)-1ß, IL-6, and IL-8, far exceeding the amount detected in blood. Genes encoding for these mediators revealed a similar profile. By comparing the wild-type with a lipopolysaccharide (LPS) deficient meningococcal strain, we documented that LPS was the dominant group of molecules inducing organ inflammation and was required for IL-8 production. IL-10 production was predominantly stimulated by non-LPS molecules. The massive organ inflammation in the porcine model was present in the three patients dying of meningococcal shock and differed markedly from the patients with lethal pneumococcal infections and sudden infant death syndrome. In conclusion, in meningococcal sepsis, a massive local inflammatory response occurs in specific organs.

A complement C5 gene mutation, c.754G>A:p.A252T, is common in the Western Cape, South Africa and found to be homozygous in seven percent of Black African meningococcal disease cases.

Patients with genetically determined deficiency of complement component 5 are usually diagnosed because of recurrent invasive Neisseria meningitidis infections. Approximately 40 individual cases have been diagnosed worldwide. Nevertheless, reports of the responsible genetic defects have been sporadic, and we know of no previous reports of C5 deficiency being associated with a number of independent meningococcal disease cases in particular communities. Here we describe C5 deficiency in seven unrelated Western Cape, South African families. Three different C5 mutations c.55C>T:p.Q19X, c.754G>A:p.A252T and c.4426C>T:p.R1476X were diagnosed in index cases from two families who had both presented with recurrent meningococcal disease. p.Q19X and p.R1476X have already been described in North American Black families and more recently p.Q19X in a Saudi family. However, p.A252T was only reported in SNP databases and was not associated with disease until the present study was undertaken in the Western Cape, South Africa. We tested for p.A252T in 140 patients presenting with meningococcal disease in the Cape Town area, and found seven individuals in five families who were homozygous for the mutation p.A252T. Very low serum C5 protein levels (0.1-4%) and correspondingly low in vitro functional activity were found in all homozygous individuals. Allele frequencies of p.A252T in the Black African and Cape Coloured communities were 3% and 0.66% and estimated homozygosities are 1/1100 and 1/22,500 respectively. In 2012 we reported association between p.A252T and meningococcal disease. Molecular modelling of p.A252T has indicated an area of molecular stress in the C5 molecule which may provide a mechanism for the very low level in the circulation. This report includes seven affected families indicating that C5D is not rare in South Africa.

Combined inhibition of complement C5 and CD14 markedly attenuates inflammation, thrombogenicity, and hemodynamic changes in porcine sepsis.

Complement and the TLR family constitute two important branches of innate immunity. We previously showed attenuating effects on inflammation and thromogenicity by inhibiting the TLR coreceptor CD14 in porcine sepsis. In the present study, we explored the effect of the C5 and leukotriene B4 inhibitor Ornithodoros moubata complement inhibitor (OmCI; also known as coversin) alone and combined with anti-CD14 on the early inflammatory, hemostatic, and hemodynamic responses in porcine Escherichia coli-induced sepsis. Pigs were randomly allocated to negative controls (n = 6), positive controls (n = 8), intervention with OmCI (n = 8), or with OmCI and anti-CD14 (n = 8). OmCI ablated C5 activation and formation of the terminal complement complex and significantly decreased leukotriene B4 levels in septic pigs. Granulocyte tissue factor expression, formation of thrombin-antithrombin complexes (p < 0.001), and formation of TNF-α and IL-6 (p < 0.05) were efficiently inhibited by OmCI alone and abolished or strongly attenuated by the combination of OmCI and anti-CD14 (p < 0.001 for all). Additionally, the combined therapy attenuated the formation of plasminogen activator inhibitor-1 (p < 0.05), IL-1ß, and IL-8, increased the formation of IL-10, and abolished the expression of wCD11R3 (CD11b) and the fall in neutrophil cell count (p < 0.001 for all). Finally, OmCI combined with anti-CD14 delayed increases in heart rate by 60 min (p < 0.05) and mean pulmonary artery pressure by 30 min (p < 0.01). Ex vivo studies confirmed the additional effect of combining anti-CD14 with OmCI. In conclusion, upstream inhibition of the key innate immunity molecules, C5 and CD14, is a potential broad-acting treatment regimen in sepsis as it efficiently attenuated inflammation and thrombogenicity and delayed hemodynamic changes.

Complement activation by candidate biomaterials of an implantable microfabricated medical device.

Implantable devices realized by microfabrication have introduced a new class of potential biomaterials whose properties would need to be assessed. Such devices include sensors for measuring biological substances like glucose. Thus, 14 different candidate materials intended for design of such a device were investigated with respect to their complement activation potential in human serum. The fluid-phase activation was measured by the products C4d, Bb, C3bc, and the terminal complement complex (TCC), whereas solid-phase activation was measured by deposition of TCC on the material surfaces. No fluid-phase activation was found for materials related to the capsule, carrier, or sealing. Fluid-phase activation was, however, triggered to a various extent in three of the four nanoporous membranes (cellulose, polyamide, and aluminium oxide), whereas polycarbonate was rendered inactive. Solid-phase activation discriminated more sensitively between all the materials, revealing that the capsule candidate polydimethylsiloxane and sealing candidate silicone 3140 were highly compatible, showing significantly lower TCC deposition than the negative control (p < 0.01). Three of the candidate materials were indifferent, whereas the remaining nine showed significantly higher deposition of TCC than the negative control (p < 0.01). In conclusion, complement activation, in particular when examined on the solid phase, discriminated well between the different candidate materials tested and could be used as a guide for the selection of the best-suited materials for further investigation and development of the device.

Dissecting the effects of lipopolysaccharides from nonlipopolysaccharide molecules in experimental porcine meningococcal sepsis.

OBJECTIVE: To dissect the in vivo responses to lipopolysaccharide compared with nonlipopolysaccharide structures of whole meningococci. DESIGN: Comparative experimental study. SETTING: University hospital with an animal intensive care unit and laboratory. SUBJECTS: Twenty-four anesthetized healthy Norwegian landrace pigs of 30 kg (+/- 2.5 kg) grouped into two test groups and one control group. INTERVENTIONS: Exponentially increasing numbers of Neisseria meningitidis H44/76 (NmLPS+) or a knockout mutant of H44/76 completely lacking lipopolysaccharide (NmLPS-) were infused intravenously to the pigs. MEASUREMENTS AND MAIN RESULTS: Physiological and hematologic parameters were continuously recorded and biochemical analyses were performed in batch after completion. Systemic vascular resistance, cardiac index and lactate changed significantly more in the NmLPS+ than in the NmLPS- group (p < .05). Mean pulmonary artery pressure increased early in the NmLPS+ and late in the NmLPS- group, but finally reached equally high values. Capillary leakage (fluid requirement, plasma albumin loss, organ wet/dry ratio) was more prominent in the NmLPS+ group (p < .05). Leukocytes were depleted in a highly lipopolysaccharide-dependent manner (p < .001). Thrombin-antithrombin complexes and plasminogen activator inhibitor-1 increased 2.5 to five times more in the NmLPS+ group (p < .05). Maximum cytokine concentrations in plasma were markedly higher in the NmLPS+ group (p < .05): tumor necrosis factor-alpha (40 times), interleukin-1beta (40 times), interleukin-6 (13 times), and interleukin-10 (four times). Interleukin-12 increased only in the NmLPS+ group. CONCLUSION: This large animal model, which simulates human disease well, confirms the potency of lipopolysaccharide but provides clear evidence that nonlipopolysaccharide molecules induce cardiovascular and hematologic changes quite similar to those caused by lipopolysaccharide. In general, 10- to 20-fold higher doses of the lipopolysaccharide-deficient mutant were required to induce the same degree of pathophysiological changes. Endotoxic activity of Gram-negative bacteria should no longer be attributed solely to the activity of lipopolysaccharide.