Canine IL4-10 fusion protein provides disease modifying activity in a canine model of OA; an exploratory study.

OBJECTIVE: An ideal disease modifying osteoarthritis drug (DMOAD) has chondroprotective, anti-inflammatory, and analgesic effects. This study describes the production and characterization of a canine IL4-10 fusion protein (IL4-10 FP) and evaluates its in vivo DMOAD activity in a canine model of osteoarthritis (OA). DESIGN: The canine Groove model was used as an in vivo model of degenerative knee OA. Six weeks after OA induction dogs were intra-articularly injected weekly, for ten weeks, with either IL4-10 FP or phosphate buffered saline (PBS). In addition to the use of human IL4-10 FP, canine IL4-10 FP was developed and characterized in vitro, and tested in vivo. Force plate analysis (FPA) was performed to analyze joint loading as a proxy measure for pain. After ten weeks dogs were euthanized and cartilage and synovial tissue samples were analyzed by histochemistry (OARSI scores) and biochemistry (cartilage proteoglycan turnover). RESULTS: Repetitive intra-articular injections with human IL4-10 FP led to antibody formation, that blocked its functional activity. Therefore, a canine IL4-10 FP was developed, which completely inhibited LPS-induced TNFα production by canine blood cells, and increased proteoglycan synthesis of canine cartilage in vitro (p = 0.043). In vivo, canine IL4-10 FP restored the, by OA impaired, joint loading (p = 0.002) and increased cartilage proteoglycan content (p = 0.029). CONCLUSIONS: This first study on the potential DMOAD activity upon prolonged repeated treatment with IL4-10 FP demonstrates that a species-specific variant has anti-inflammatory and chondroprotective effects in vitro and chondroprotective and analgesic effects in vivo. These data warrant further research on the DMOAD potential of the IL4-10 FP.

IL4-10 fusion protein: a novel immunoregulatory drug combining activities of interleukin 4 and interleukin 10.

The objective of this study was to test the capacity of a newly developed fusion protein of interleukin 4 (IL-4) and IL-10 [IL4-10 fusion protein (FP)] to shift multiple pro-inflammatory pathways towards immune regulation, and to inhibit pro-inflammatory activity in arthritis models. The effects of IL4-10 FP in comparison with IL-4, IL-10 and IL-4 plus IL-10 on pro- and anti-inflammatory mediators, T cells and immunoglobulin (Ig) receptors in favour of immunoregulatory activity were studied. In addition, the capacity of IL4-10 FP to inhibit pro-inflammatory activity in ex-vivo and in-vivo arthritis models was investigated. IL4-10 FP robustly inhibited pro-inflammatory cytokine [IL-1ß, tumour necrosis factor (TNF)-α, IL-6 and IL-8] production in whole blood cultures, mediated by both the IL-10 and the IL-4 moiety. IL4-10 fusion protein induced IL-1 receptor antagonist (IL-1RA) production and preserved soluble TNF receptor (sTNFR) levels, strongly increasing IL-1RA/IL-1ß and sTNFR/TNF-α ratios. In addition, IL4-10 FP strongly inhibited T helper (Th) type 1 and 17 cytokine secretion, while maintaining FoxP3 expression and up-regulating Th2 activity. In addition, while largely leaving expression of activating Fc gamma receptor (FcγR)I, III and Fc epsilon receptor (FcεR) unaffected, it significantly shifted the FcγRIIa/FcγRIIb ratio in favour of the inhibitory FcγRIIb. Moreover, IL4-10 FP robustly inhibited secretion of pro-inflammatory cytokines by rheumatoid arthritis synovial tissue and suppressed experimental arthritis in mice, without inducing B cell hyperactivity. IL4-10 fusion protein is a novel drug, signalling cells to induce immunoregulatory activity that overcomes limitations of IL-4 and IL-10 stand-alone therapy, and therefore has therapeutic potential for inflammatory diseases such as rheumatoid arthritis.

IL4-10 fusion protein has chondroprotective, anti-inflammatory and potentially analgesic effects in the treatment of osteoarthritis.

OBJECTIVE: Effective disease-modifying drugs for osteoarthritis (DMOAD) should preferably have chondroprotective, anti-inflammatory, and analgesic activity combined in a single molecule. We developed a fusion protein of IL4 and IL10 (IL4-10 FP), in which the biological activity of both cytokines is preserved. The present study evaluates the chondroprotective, anti-inflammatory, and analgesic activity of IL4-10 FP in in vitro and in vivo models of osteoarthritis. METHODS: Human osteoarthritic cartilage tissue and synovial tissue were cultured with IL4-10 FP. Cartilage proteoglycan turnover and release of pro-inflammatory, catabolic, and pain mediators by cartilage and synovial tissue were measured. The analgesic effect of intra-articularly injected IL4-10 FP was evaluated in a canine model of osteoarthritis by force-plate analysis. RESULTS: IL4-10 FP increased synthesis (P = 0.018) and decreased release (P = 0.018) of proteoglycans by osteoarthritic cartilage. Release of pro-inflammatory IL6 and IL8 by cartilage and synovial tissue was reduced in the presence of IL4-10 FP (all P < 0.05). The release of MMP3 by osteoarthritic cartilage and synovial tissue was decreased (P = 0.018 and 0.028) whereas TIMP1 production was not significantly changed. Furthermore, IL4-10 FP protected cartilage against destructive properties of synovial tissue mediators shown by the increased cartilage proteoglycan synthesis (P = 0.0235) and reduced proteoglycan release (P = 0.0163). Finally, intra-articular injection of IL4-10 FP improved the deficient joint loading in dogs with experimentally induced osteoarthritis. CONCLUSION: The results of current preliminary study suggest that IL4-10 FP has DMOAD potentials since it shows chondroprotective and anti-inflammatory effects in vitro, as well as potentially analgesic effect in a canine in vivo model of osteoarthritis.

Differential effects of donor-specific HLA antibodies in living versus deceased donor transplant.

The presence of donor-specific anti-HLA antibodies (DSAs) is associated with increased risk of graft failure after kidney transplant. We hypothesized that DSAs against HLA class I, class II, or both classes indicate a different risk for graft loss between deceased and living donor transplant. In this study, we investigated the impact of pretransplant DSAs, by using single antigen bead assays, on long-term graft survival in 3237 deceased and 1487 living donor kidney transplants with a negative complement-dependent crossmatch. In living donor transplants, we found a limited effect on graft survival of DSAs against class I or II antigens after transplant. Class I and II DSAs combined resulted in decreased 10-year graft survival (84% to 75%). In contrast, after deceased donor transplant, patients with class I or class II DSAs had a 10-year graft survival of 59% and 60%, respectively, both significantly lower than the survival for patients without DSAs (76%). The combination of class I and II DSAs resulted in a 10-year survival of 54% in deceased donor transplants. In conclusion, class I and II DSAs are a clear risk factor for graft loss in deceased donor transplants, while in living donor transplants, class I and II DSAs seem to be associated with an increased risk for graft failure, but this could not be assessed due to their low prevalence.

A fusion protein of interleukin-4 and interleukin-10 protects against blood-induced cartilage damage in vitro and in vivo.

Essentials Targeted treatment for hemophilic arthropathy, still causing significant morbidity, is lacking. This study evaluates the efficacy of a fusion of protein of interleukin(IL)-4 and IL-10. In vitro the fusion protein prevents blood-induced cartilage damage in a dose-dependent manner. In hemophilic mice, the IL4-10 fusion protein ameliorates cartilage damage upon joint bleeding. SUMMARY: Background Joint damage still causes significant morbidity in hemophilia. It results from synovial inflammation and direct cartilage-degenerating properties of blood components. Interleukin (IL)-4 and IL-10 have been shown to protect cartilage from blood-induced damage. Recently an IL4-10 fusion protein has been developed to combine the function of IL-4 and IL-10 and increase their bioavailability. Objectives In this study we evaluate whether this IL4-10 fusion protein protects against blood-induced joint damage. Methods In vitro, human cartilage explants were exposed to whole blood and simultaneously to a broad concentration range of the IL4-10 fusion protein. Effects on cartilage matrix turnover were compared with the individual cytokines. Moreover, the influence of the fusion protein and its individual components on IL-1ß and IL-6 production was investigated. In hemophilia A mice, the effect of intra-articular treatment on synovitis and cartilage damage resulting from joint bleeding was evaluated by histochemistry. Results In vitro, the fusion protein prevented blood-induced cartilage damage in a dose-dependent manner, with equal effectiveness to the combination of the separate cytokines. In whole blood cultures 10 ng mL-1 fusion protein completely blocked the production of IL-1ß and IL-6 by monocytes/macrophages. In hemophilic mice, intra-articular injection of IL-4 and IL-10 did not influence synovitis or cartilage degeneration. In contrast, equimolar amounts of the fusion protein attenuated cartilage damage upon repeated joint bleeding, although synovial inflammation was hardly affected. Conclusions Overall, this study shows that the IL4-10 fusion protein prevents blood-induced cartilage damage in vitro and ameliorates cartilage degeneration upon joint bleeding in hemophilic mice.

Targeting CD1c-expressing classical dendritic cells to prevent thymus and activation-regulated chemokine (TARC)-mediated T-cell chemotaxis in rheumatoid arthritis.

OBJECTIVES: Thymus and activation-regulated chemokine (TARC) attracts cells that express the C-C chemokine receptor type 4 (CCR4), including CD4 T cells. As expression of CCR4 is increased on peripheral T cells and intra-articular interleukin (IL)-17-producing cells in patients with rheumatoid arthritis (RA), we investigated whether TARC plays a role in the attraction of T cells to the synovial compartment. In addition, we assessed the role of classical dendritic cells (cDCs) in the production of TARC in RA. METHOD: TARC was measured in synovial fluid (SF) samples from RA and osteoarthritis (OA) patients. Spontaneous and thymic stromal lymphopoietin (TSLP)-induced TARC production by mononuclear cells (MCs) and CD1c cDCs from peripheral blood (PB) and SF was assessed. The role of TARC in CD4 T-cell migration towards cDCs was assessed and the contribution of CD1c-expressing cells to TARC production was studied. RESULTS: TARC concentrations were higher in SF of RA patients compared to OA patients. MCs from SF produced TARC spontaneously and produced more TARC upon stimulation than paired PBMCs. Blocking TARC strongly inhibited CD4 T-cell chemotaxis by TSLP-stimulated cDCs, associated with decreased production of tumour necrosis factor (TNF)-α. Depletion of cDCs from SFMCs strongly reduced TARC production. CONCLUSIONS: TARC levels are increased in RA SF and our data indicate that this results from production by SFMCs and in particular CD1c cDCs. TARC attracts T cells and TARC secretion by MCs is crucially dependent on the presence of CD1c cDCs. Considering the potential of SF cDCs to activate T cells and induce pro-inflammatory cytokine secretion, targeting intra-articular cDCs constitutes a novel therapeutic approach in RA.

How can we reduce costs of solid-phase multiplex-bead assays used to determine anti-HLA antibodies?

Solid-phase multiplex-bead assays are widely used in transplantation to detect anti-human leukocyte antigen (HLA) antibodies. These assays enable high resolution detection of low levels of HLA antibodies. However, multiplex-bead assays are costly and yield variable measurements that limit the comparison of results between laboratories. In the context of a Dutch national Consortium study we aimed to determine the inter-assay and inter-machine variability of multiplex-bead assays, and we assessed how to reduce the assay reagents costs. Fifteen sera containing a variety of HLA antibodies were used yielding in total 7092 median fluorescence intensities (MFI) values. The inter-assay and inter-machine mean absolute relative differences (MARD) of the screening assay were 12% and 13%, respectively. The single antigen bead (SAB) inter-assay MARD was comparable, but showed a higher lot-to-lot variability. Reduction of screening assay reagents to 50% or 40% of manufacturers' recommendations resulted in MFI values comparable to 100% of the reagents, with an MARD of 12% or 14%, respectively. The MARD of the 50% and 40% SAB assay reagent reductions were 11% and 22%, respectively. From this study, we conclude that the reagents can be reliably reduced at least to 50% of manufacturers' recommendations with virtually no differences in HLA antibody assignments.

IL4-10 Fusion Protein Is a Novel Drug to Treat Persistent Inflammatory Pain.

UNLABELLED: Chronic pain is a major clinical problem that is difficult to treat and requires novel therapies. Although most pain therapies primarily target neurons, neuroinflammatory processes characterized by spinal cord and dorsal root ganglion production of proinflammatory cytokines play an important role in persistent pain states and represent potential therapeutic targets. Anti-inflammatory cytokines are attractive candidates to regulate aberrant neuroinflammatory processes, but the therapeutic potential of these cytokines as stand-alone drugs is limited. Their optimal function requires concerted actions with other regulatory cytokines, and their relatively small size causes rapid clearance. To overcome these limitations, we developed a fusion protein of the anti-inflammatory cytokines interleukin 4 (IL4) and IL10. The IL4-10 fusion protein is a 70 kDa glycosylated dimeric protein that retains the functional activity of both cytokine moieties. Intrathecal administration of IL4-10 dose-dependently inhibited persistent inflammatory pain in mice: three IL4-10 injections induced full resolution of inflammatory pain in two different mouse models of persistent inflammatory pain. Both cytokine moieties were required for optimal effects. The IL4-10 fusion protein was more effective than the individual cytokines or IL4 plus IL10 combination therapy and also inhibited allodynia in a mouse model of neuropathic pain. Mechanistically, IL4-10 inhibited the activity of glial cells and reduced spinal cord and dorsal root ganglion cytokine levels without affecting paw inflammation. In conclusion, we developed a novel fusion protein with improved efficacy to treat pain, compared with wild-type anti-inflammatory cytokines. The IL4-10 fusion protein has potential as a treatment for persistent inflammatory pain. SIGNIFICANCE STATEMENT: The treatment of chronic pain is a major clinical and societal challenge. Current therapies to treat persistent pain states are limited and often cause major side effects. Therefore, novel analgesic treatments are urgently needed. In search of a novel drug to treat chronic pain, we developed a fusion protein consisting of two prototypic regulatory cytokines, interleukin 4 (IL4) and IL10. The work presented in this manuscript shows that this IL4-10 fusion protein overcomes some major therapeutic limitations of pain treatment with individual cytokines. The IL4-10 fusion protein induces full resolution of persistent inflammatory pain in two different mouse models. These novel findings are significant, as they highlight the IL4-10 fusion protein as a long-needed potential new drug to stop persistent pain states.

A Promoter Polymorphism in the CD59 Complement Regulatory Protein Gene in Donor Lungs Correlates With a Higher Risk for Chronic Rejection After Lung Transplantation.

Complement activation leads primarily to membrane attack complex formation and subsequent target cell lysis. Protection against self-damage is regulated by complement regulatory proteins, including CD46, CD55, and CD59. Within their promoter regions, single-nucleotide polymorphisms (SNPs) are present that could influence transcription. We analyzed these SNPs and investigated their influence on protein expression levels. A single SNP configuration in the promoter region of CD59 was found correlating with lower CD59 expression on lung endothelial cells (p = 0.016) and monocytes (p = 0.013). Lung endothelial cells with this SNP configuration secreted more profibrotic cytokine IL-6 (p = 0.047) and fibroblast growth factor ß (p = 0.036) on exposure to sublytic complement activation than cells with the opposing configuration, whereas monocytes were more susceptible to antibody-mediated complement lysis (p < 0.0001). Analysis of 137 lung transplant donors indicated that this CD59 SNP configuration correlates with impaired long-term survival (p = 0.094) and a significantly higher incidence of bronchiolitis obliterans syndrome (p = 0.046) in the recipient. These findings support a role for complement in the pathogenesis of this posttransplant complication and are the first to show a deleterious association of a donor CD59 promoter polymorphism in lung transplantation.

Elevated D-dimers in attacks of hereditary angioedema are not associated with increased thrombotic risk.

BACKGROUND: Recommended management of attacks of hereditary angioedema (HAE) due to C1 esterase inhibitor (C1-INH) deficiency (C1-INH-HAE) includes therapy with exogenous C1INH. Thrombotic/thromboembolic events (TEE) have been reported with plasma-derived C1INH, but so far none with recombinant human C1INH (rhC1INH). This phase III, randomized, placebo (saline)-controlled study evaluated the safety of rhC1INH 50 IU/kg for the treatment of acute attacks in 74 patients with C1-INH-HAE. METHODS: Monitoring for TEE and assessment of risk of deep vein thrombosis (DVT) by the Wells prediction rule were performed, and levels of fibrin degradation products (plasma D-dimers) were assessed before study drug administration (baseline), 2 h, and 7 days posttreatment. RESULTS: Plasma D-dimer levels were elevated in 80% of the patients (median [25th-75th percentiles]: 2149 [480-5105] µg/l; normal ≤250 µg/l) and were higher in patients with submucosal (abdominal, oropharyngeal-laryngeal) attacks (3095 [890-10000] µg/l; n = 29) compared with subcutaneous (peripheral, facial) attacks (960 [450-4060] µg/l; n = 35). Median plasma D-dimer levels were comparable across treatment groups at baseline (1874 [475-4568] µg/l rhC1INH; 2259 [586-7533] µg/l saline) and 2 h postinfusion (2389 [760-4974] µg/l rhC1INH; 2550 [310-8410] µg/l saline); median plasma D-dimer levels were decreased by Day 7 in both groups (425 [232-3240] µg/l rhC1INH; 418 [246-2318] µg/l saline). No increased risk of DVT was identified, nor any TEE reported in rhC1INH treated or controls. CONCLUSION: Elevated plasma D-dimer levels were associated with acute C1-INH-HAE attacks, particularly with submucosal involvement. However, rhC1INH therapy was not associated with thrombotic events.

Anti-ETAR and anti-AT1R autoantibodies are elevated in patients with endstage cystic fibrosis.

Autoantibodies against endothelin-1 type A receptor (ETAR) are present in systemic sclerosis complicated by lung fibrosis and pulmonary hypertension. As increased serum levels and local overproduction of endothelin-1 in the airways are reported in cystic fibrosis (CF) patients, we reasoned that anti-ETAR antibodies could be prevalent in endstage CF patients prior to lung transplantation (LTx). Also, ETAR autoantibodies are frequently associated with autoantibodies against the angiotensin II type 1 receptor (AT1R). We analyzed the presence of anti-ETAR and anti-AT1R autoantibodies in 43 LTx patients (chronic obstructive pulmonary disease (COPD), n=20; CF, n=13; interstitial lung disease (ILD), n=1). We observed overall higher anti-ETAR and anti-AT1R autoantibody titers in sera taken prior to LTx in the CF patient group as compared to COPD. No difference was found in autoantibody levels between patients with CF versus ILD. In sera taken post-LTx we found the same difference in anti-ETAR and anti-AT1R autoantibody titers between patients with CF versus COPD. No difference was found in antibody titers between sera taken prior to or 6 months after LTx. There was no association between autoantibody levels and other relevant demographic parameters, and we found no association between autoantibody titers and the development of the bronchiolitis obliterans syndrome. Both autoantibody titers were strongly correlated. We hypothesize that due to prolonged exposure to bacterial infection, increased levels of AT1R and ETAR result in a deregulated immune response causing autoantibody formation. Further research is expedient to elucidate the occurrence of autoantibodies against ETAR and AT1R and their role in disease progression.

The PROCARE consortium: toward an improved allocation strategy for kidney allografts.

Kidney transplantation is the best treatment option for patients with end-stage renal failure. At present, approximately 800 Dutch patients are registered on the active waiting list of Eurotransplant. The waiting time in the Netherlands for a kidney from a deceased donor is on average between 3 and 4 years. During this period, patients are fully dependent on dialysis, which replaces only partly the renal function, whereas the quality of life is limited. Mortality among patients on the waiting list is high. In order to increase the number of kidney donors, several initiatives have been undertaken by the Dutch Kidney Foundation including national calls for donor registration and providing information on organ donation and kidney transplantation. The aim of the national PROCARE consortium is to develop improved matching algorithms that will lead to a prolonged survival of transplanted donor kidneys and a reduced HLA immunization. The latter will positively affect the waiting time for a retransplantation. The present algorithm for allocation is among others based on matching for HLA antigens, which were originally defined by antibodies using serological typing techniques. However, several studies suggest that this algorithm needs adaptation and that other immune parameters which are currently not included may assist in improving graft survival rates. We will employ a multicenter-based evaluation on 5429 patients transplanted between 1995 and 2005 in the Netherlands. The association between key clinical endpoints and selected laboratory defined parameters will be examined, including Luminex-defined HLA antibody specificities, T and B cell epitopes recognized on the mismatched HLA antigens, non-HLA antibodies, and also polymorphisms in complement and Fc receptors functionally associated with effector functions of anti-graft antibodies. From these data, key parameters determining the success of kidney transplantation will be identified which will lead to the identification of additional parameters to be included in future matching algorithms aiming to extend survival of transplanted kidneys and to diminish HLA immunization. Computer simulation studies will reveal the number of patients having a direct benefit from improved matching, the effect on shortening of the waiting list, and the decrease in waiting time.

Immunoglobulin M, C-reactive protein and complement activation in rat hepatic ischemia-reperfusion injury.

BACKGROUND: Ischemia-reperfusion (I/R) models have shown that C-reactive protein (CRP) and immunoglobulin M (IgM) are involved in complement activation. Binding of CRP and IgM to damaged cell membranes initiates complement activation and aggravates I/R injury in various organs. However, the time course of CRP- and IgM-mediated complement activation and the relation to hepatocellular injury and inflammation in liver I/R are unknown. AIM: To evaluate the time course of IgM- and CRP-related complement activation and the relation to hepatocellular injury and inflammation in a hepatic I/R rat model. METHODS: Male Wistar rats were allocated to (1) five groups of animals exposed to 60 min of partial ischemia (70%) induced via clamping of the left segmental portal triad, followed by 0, 3, 6, 12 or 24 h of reperfusion (n = 6 in each group); (2) five groups of sham-operated animals with corresponding reperfusion times (n = 5), and (3) a control group sacrificed before ischemia (n = 5). Hepatocellular injury, inflammatory response, rat plasma CRP and IgM levels and immunohistochemical depositions of CRP, IgM and C3 were assessed for each group. RESULTS: Histopathological injury scores of hematoxylin and eosin sections of ischemic liver lobes demonstrated increasing values throughout the reperfusion time with a peak at 12 h. Plasma aminotransferases (alanine aminotransferase and aspartate aminotransferase) significantly increased after 3 h of reperfusion, peaking at 6 h (3,100 ± 800 U/l; p < 0.05). Hepatic neutrophil influx significantly increased from 3 to 6 h of reperfusion (p < 0.05) and demonstrated the highest value at 12 h (1.1 ± 0.2 U/mg of protein). Plasma IL-6 levels in the ischemia groups showed peak values after 6 h of reperfusion, decreasing significantly thereafter (p < 0.05). Plasma CRP values reached highest levels after 3 h of reperfusion (mean 91 ± 5% of control pool), decreasing significantly thereafter. Rat IgM concentrations in plasma did not significantly change throughout the reperfusion time. Immunohistochemical depositions of IgM, CRP and C3 in ischemic lobes demonstrated a similar pattern in time, reaching maximum values at 12 h of reperfusion. The percentages of depositions of CRP and IgM were significantly correlated [r(S) = 0.569; p < 0.001; Spearman test]. The time course of C3 and CRP depositions throughout reperfusion and C3 and IgM staining were significantly similar [r(S) = 0.797 and r(S) = 0.656, respectively; p < 0.0001; ANOVA]. CONCLUSIONS: CRP and IgM depositions demonstrate a parallel time course throughout the reperfusion to hepatocellular damage, inflammatory response and activated complement deposition in this rat hepatic I/R model. Furthermore, the time course of CRP and IgM depositions was significantly similar to that of activated complement depositions.

C-reactive protein levels in hereditary angioedema.

Hereditary angioedema (HAE) patients experience recurrent episodes of angioedema attacks that can be painful, disfiguring and even life-threatening. The disorder results from a mutation in the gene that controls the synthesis of C1-inhibitor (C1INH). C1INH is a major regulator of activation of the contact system. It is often assumed that attacks results from uncontrolled local activation of the contact system with subsequent formation of bradykinin. To evaluate the involvement of inflammatory reactions in HAE, we analysed C-reactive protein (CRP) levels. HAE patients included in a clinical database of recombinant human C1-inhibitor (rhC1INH) studies were evaluated. For the current study we analysed CRP levels when patients were asymptomatic, during a clinical attack and in a follow-up period, and correlated these with the clinical manifestations of the attack. Data from 68 HAE patients were analysed and included CRP levels on 273 occasions. While asymptomatic, 20% of the patients analysed had increased CRP. At the onset of the attack (P = 0·049) and during the next 24 h CRP rose significantly (P = 0·002) in patients with an abdominal location, and post-attack levels were significantly higher in these patients than in patients with attacks at other locations (P = 0·034). In conclusion, CRP levels are elevated in a substantial proportion of asymptomatic HAE patients. Levels of CRP increase significantly during an abdominal attack. These data suggest low-grade systemic inflammatory reactions in HAE patients as well as a triggering event for attacks that starts prior to symptom onset.

Anti-BPIFA1/SPLUNC1: a new autoantibody prevalent in patients with endstage cystic fibrosis.

BACKGROUND: Bactericidal/permeability increasing protein fold containing family A (BPIFA) 1, is a secreted protein of the upper airways that shares structural homology with BPI and exhibits comparable antimicrobial capacities. We hypothesized that CF patients have circulating IgG or IgA anti-BPIFA1 autoantibodies, similarly as reported for BPI autoantibodies. METHODS: We analyzed pre- and post-transplantation sera from 67 endstage lung disease patients who underwent lung transplantation (LTx) because of COPD (n=27), CF (n=25), and ILD (n=15). RESULTS: Anti-BPIFA1 (48%) and anti-BPI (92%) were elevated in CF patients compared to healthy controls, with anti-BPIFA1 IgG isotype being most prevalent, whereas anti-BPI is of the IgA isotype. Levels of anti-BPI autoantibodies significantly declined post-LTx, whereas anti-BPIFA1 did not. No relation was found between autoantibodies against BPIFA1 and BPI. CONCLUSION: Our results indicate that BPIFA1 is a novel target for autoantibodies in CF. The function of these autoantibodies needed to be investigated in future studies.

Two novel inhibitory anti-human factor XI antibodies prevent cessation of blood flow in a murine venous thrombosis model.

Coagulation factor XI (FXI) is a promising target for anticoagulation, because of its major role in thrombosis and relatively minor role in haemostasis. This implies that inhibition of FXI can prevent thrombosis without causing bleeding. It was our aim to investigate the antithrombotic properties of two novel inhibitory anti-human FXI antibodies (αFXI-175 and αFXI-203). The in vitro properties of both antibodies were analysed using standard clotting assays and calibrated automated thrombography. For the in vivo model we used FXI knockout mice, in which FXI plasma levels were restored with purified human FXI. Thrombosis was induced by applying ferric chloride to the vena cava inferior, after which time to occlusion was analysed. A tail bleeding assay was used to investigate the safety of both antibodies. Using calibrated automated thrombography, both antibodies inhibited thrombin generation initiated via the intrinsic pathway. In contrast, upon tissue factor (TF)-initiated thrombin generation, αFXI-203 did not inhibit thrombin generation, while αFXI-175 inhibited thrombin generation only at low concentrations of TF. In the murine thrombosis model, the vena cava inferior remained patent for 25 minutes (min) in mice treated with αFXI-175 and for 12.5 min in αFXI-203 treated animals, which was significantly longer than in placebo-treated animals (5 min, p<0.05). Neither antibody caused severe blood loss in a tail bleeding assay. In conclusion, the two inhibitory antibodies against FXI prevented cessation of blood flow in a murine thrombosis model without inducing a bleeding tendency.

Cerebral and hepatic inflammatory response after neonatal hypoxia-ischemia in newborn rats.

BACKGROUND: Neonatal encephalopathy induced by perinatal asphyxia is a serious condition associated with high mortality and morbidity. Inflammation after the insult is thought to contribute to brain injury. This inflammatory response to hypoxia-ischemia (HI) may not only occur in the brain but also in peripheral organs. The aim of the present study was to investigate the effect of neonatal HI on the inflammatory response in the liver in comparison to inflammation in the brain. METHODS: HI was induced in P7 Wistar rats by unilateral carotid artery occlusion and hypoxia. Cytokine and chemokine mRNA levels were determined in the brain and liver by quantitative PCR. Polarization of brain macrophages to the M1/M2-like phenotype and infiltration of neutrophils were characterized by immunohistochemistry. RESULTS: 3 h after HI, an upregulation of the proinflammatory cytokines TNF-α and IL-1ß and anti-inflammatory IL-10 was observed in the ipsilateral hemisphere of the brain compared to mRNA levels in sham-operated animals. Additionally, cerebral CINC-1 and MCP-1 mRNA expressions were increased. We also observed increased numbers of macrophages/microglia of the M1-like phenotype as well as a small increase in granulocyte influx in the ipsilateral hemisphere. Conversely, in the liver 3 h after HI, a downregulation of TNF-α, IL-1ß, and MCP-1 and a trend towards an upregulation of IL-10 were observed compared to mRNA levels of sham-operated animals. However, hepatic CINC-1 expression was increased compared to levels in sham-operated animals. Following systemic hypoxia only, no significant changes in the expression of TNF-α, CINC-1 or MCP-1 were observed in the liver compared to sham-operated littermates, except for an upregulation in hepatic IL-1ß expression 3 h after hypoxia. Twenty-four hours after insult, cerebral ipsilateral TNF-α, MCP-1 and CINC-1 mRNA expression was still increased, together with an increase in TGF-ß expression. Moreover, an increase in macrophages/microglia of the M1-like phenotype was observed together with the appearance of macrophages/microglia of the M2-like phenotype around the cerebral lesion as well as an increase in granulocyte influx in comparison to 3 h after HI. In the liver, 24 h after HI, cytokine and chemokine responses were similar to mRNA levels in sham-operated animals except for a decrease in IL-10 and MCP-1. CONCLUSION: We describe for the first time that brain damage following neonatal HI induces an early downregulation of the proinflammatory response in the liver. HI induces an early proinflammatory response in the brain with a concomitant increase in influx of neutrophils and polarization of macrophages/microglia to the M1-like phenotype starting at 3 h and increasing up to 24 h after HI. The inflammatory state of the brain changes after 24 h, with an increase in the anti-inflammatory cytokine TGF-ß together with the appearance of macrophages/microglia of the M2-like phenotype. The downregulation of proinflammatory cytokines in the liver is not due to systemic hypoxia only, but is induced by the cerebral damage.

Target levels of functional C1-inhibitor in hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is a heterozygous deficiency of first component of complement-inhibitor (C1INH). Insufficient C1INH activity leads to uncontrolled activation of plasma cascade systems, which results in acute angioedema attacks in patients with HAE. Plasma-derived or recombinant C1INH products are approved for the treatment of such angioedema attacks. The target level of C1INH activity needed to achieve optimal efficacy, however, remains unknown. We determined the plasma level of C1INH associated with optimal clinical efficacy in the treatment of angioedema attacks. METHODS: Efficacy and pharmacokinetic data were reviewed from recently published placebo-controlled randomized trials in the treatment of HAE with either plasma-derived or recombinant C1INH products, tested at various doses. RESULTS: A dose-dependent effect was observed on time to the beginning of relief of symptoms, on time to resolution of symptoms, and on the response rate within 4 h. Optimal efficacy of C1INH therapy is achieved at doses ≥50 U/kg. This dose increases plasma C1INH activity in almost all patients to values ≥0.7 U/ml (70% of normal), the lower limit of the normal range. The differences in half-lives of the various C1INH products do not have an obvious effect on clinical efficacy. CONCLUSION: A review of the efficacy and pharmacokinetic data from recently published controlled studies in the treatment of HAE attacks suggests that efficacy of C1INH therapy is optimal when C1INH activity levels are restored to the normal range.

Complement activation on the surface of cell-derived microparticles during cardiac surgery with cardiopulmonary bypass - is retransfusion of pericardial blood harmful?

OBJECTIVES: To investigate whether cell-derived microparticles play a role in complement activation in pericardial blood of patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and whether microparticles in pericardial blood contribute to systemic complement activation upon retransfusion. METHODS: Pericardial blood of 13 patients was retransfused in 9 and discarded in 4 cases. Microparticles were isolated from systemic blood collected before anesthesia (T1) and at the end of CPB (T2), and from pericardial blood. The microparticles were analyzed by flow cytometry for bound complement components C1q, C4 and C3, and bound complement activator molecules C-reactive protein (CRP), serum amyloid P-component (SAP), immunoglobulin (Ig)M and IgG. Fluid-phase complement activation products (C4b/c, C3b/c) and activator molecules were determined by ELISA. RESULTS: Compared with systemic T1 blood, pericardial blood contained increased C4b/c and C3b/c, and increased levels of microparticles with bound complement components. In systemic T1 samples, microparticle-bound CRP, whereas in pericardial blood, microparticle-bound SAP and IgM were associated with complement activation. At the end of CPB, increased C3b/c (but not C4b/c) was present in systemic T2 blood compared with T1, while concentrations of microparticles binding complement components and of those binding complement activator molecules were similar. Concentrations of fluid-phase complement activation products and microparticles were similar in patients whether or not retransfused with pericardial blood. CONCLUSIONS: In pericardial blood of patients undergoing cardiac surgery with CPB, microparticles contribute to activation of the complement system via bound SAP and IgM. Retransfusion of pericardial blood, however, does not contribute to systemic complement activation.

C-reactive protein in myocardial infarction binds to circulating microparticles but is not associated with complement activation.

BACKGROUND: C-reactive protein (CRP) is elevated in patients with acute myocardial infarction (AMI). When CRP binds to membrane phospholipids or Fc receptors, it activates the complement system. Recent studies show that CRP can be exposed on cell-derived microparticles (MP) and is associated complement activation. OBJECTIVES: We studied complement activation on circulating MP in AMI patients and healthy controls. METHODS: MP were isolated from plasma of AMI patients (n=21) and sex- and age-matched healthy individuals (n=10), and analyzed by flow cytometry for bound complement components (C1q, C4, C3) and complement inhibitor and activator molecules (C4bp, CRP, serum amyloid P component, immunoglobulins IgM and IgG). Concurrently, the levels of fluid phase complement activation products and inhibitor and activator molecules were determined. RESULTS: Fluid phase CRP, MP with bound CRP (CRP + MP), and C3 activation products were elevated in AMI patients compared to controls (P=0.032, P=0.031 and P=0.023, respectively), and fluid phase CRP correlated with CRP+ MP (r=0.84, P<0.001). Although CRP+ MP were elevated, they were not associated with C1q+ MP (r=0.32, P=0.174). In contrast, IgG+ MP were associated with C1q+ MP (r=0.73, P<0.001), C4+ MP and C3+ MP (r=0.78 and r=0.87, respectively; both P<0.001), and C4bp (r=0.63, P=0.004). In healthy individuals, CRP+ MP were strongly associated with C1q+ MP (r=0.82, P=0.007), which in turn were associated with C4+ MP and C3+ MP (r=0.68, P=0.032 and r=0.68, P=0.031, respectively). CONCLUSIONS: Despite CRP-associated complement activation on the surface of MP in healthy individuals and a strong correlation between MP-bound CRP and fluid phase CRP in AMI patients, the MP-associated complement activation is IgG- but not CRP-dependent in AMI patients.