High mobility group box-1 protein – one step closer to the clinic?

High mobility group box (HMGB)1, originally described as a nuclear protein that binds to and modifies DNA, is now regarded as a central mediator of inflammation by acting as a cytokine. HMGB1 is postulated to be particularly important as a late acting mediator of lethal septicaemia in mice. Furthermore, it has been suggested that HMGB1 plays a role in clinical conditions such as autoimmunity, acute ischaemia-reperfusion injury, cardiovascular disease and cancer. HMGB1 has emerged as a candidate for therapeutic intervention in various disease conditions. However, further basic and clinical studies are warranted to confirm the roles played by HMGB1 in clinical medicine

A role for the terminal C5-C9 complement pathway in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease characterized by damage to the alveolar epithelium, leading to fibrosis and excessive accumulation of extracellular matrix in the interstitium of the lung. In the present study we performed high-resolution proteomic profiling of bronchoalveolar lavage (BAL) from IPF patients and controls, and found that the complement pathway was highly upregulated in IPF. The proteins C5, C6, C7, C8, and C9, all of which are part of the complement end product, TCC, were all upregulated. We also found that TCC levels were increased in plasma among IPF patients compared to controls, after adjustment for age, sex and BMI [mean (SD) 0.62 (0.24) vs. 0.33 (0.10), p = 0.031]. These findings suggest a role for the complement system in the pathogenesis of IPF

Cholesterol crystal-induced endothelial cell activation is complement-dependent and mediated by TNF

Cholesterol crystals are known to be a hallmark of atherosclerosis with recent studies demonstrating deposition of these crystals in early fatty streak formation as well as penetrating the intima following plaque rupture. Inflammation has also become a central focus in atheroma development and endothelial cell activation is recognized as necessary for the recruitment of inflammatory cells to the plaque. However, the extent to which cholesterol crystals can induce inflammation and activate endothelial cells is not known. To investigate this, we developed a novel model activating human umbilical vein endothelial cells using lepirudin anticoagulated human whole blood. We found that cholesterol crystals caused a marked and dose-dependent increase in the adhesion molecules E-selectin and ICAM-1 on the surface of the endothelial cells after incubation with whole blood. There was no activation of the cells when the crystals were incubated in medium alone, or in human serum, despite substantial crystal-induced complement activation in serum. Complement inhibitors at the C3 and C5 levels reduced the whole blood induced endothelial cell activation by up to 89% (p < 0.05) and abolished TNF release (p < 0.01). Finally, the TNF inhibitor infliximab reduced endothelial activation to background levels (p < 0.05). In conclusion, these data demonstrate that endothelial activation by cholesterol crystals is mediated by complement-dependent TNF release, and suggests that complement-inhibition might have a role in alleviating atherosclerosis-induced inflammation.Author preprin

A parameter for IL-10 and TGF-β mediated regulation of HIV-1 specific T cell activation provides novel information and relates to progression markers

HIV replication is only partially controlled by HIV-specific activated effector T cells in chronic HIV infection and strategies are warranted to improve their efficacy. Chronic T cell activation is generally accompanied by regulation of antigen-specific T cell responses which may impair an effective control of chronic infections. The impact of HIV-induced T cell regulation on individual patients’ disease progression is largely unknown, since classical T cell activation assays reflect net activation with regulation as unknown contributing factor. We here explore a quantitative parameter for antigen-induced cytokine-mediated regulation (RAC) of HIV-specific effector T cell activation by functional antibody-blockade of IL-10 and transforming growth factor-ß. HIV Env- and Gag-specific T cell activation and RAC were estimated in peripheral blood mononuclear cells from 30 treatment-naïve asymptomatic HIV-infected progressors (CD4 count 472/µl, HIV RNA 37500 copies/ml) stimulated with overlapping peptide panels for 6 days. RAC was estimated from differences in T cell activation between normal and blocked cultures, and related to annual CD4 loss, immune activation (CD38) and microbial translocation (plasma lipopolysaccharides). RAC was heterogeneously distributed between individual patients and the two HIV antigens. Notably, RAC did not correlate to corresponding classical activation. Env RAC correlated with CD38 and CD4 loss rates (r> = 0.37, p = <0.046) whereas classical Gag activation tended to correlate with HIV RNA (r = -0.35, p = 0.06). 14 patients (47%) with low RAC’s to both Env and Gag had higher CD8 counts (p = 0.014) and trends towards lower annual CD4 loss (p = 0.056) and later start with antiretroviral treatment (p = 0.07) than the others. In contrast, patients with high RAC to both Env and Gag (n = 8) had higher annual CD4 loss (p = 0.034) and lower CD8 counts (p = 0.014). RAC to Env and Gag was not predicted by classical activation parameters and may thus provide additional information on HIV-specific immunity. RAC and other assessments of regulation deserve further in-depth exploration

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

IntroductionPlatelets 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.MethodsIn 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 DiscussionWe 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

C-reactive protein levels and depression in older and younger adults - A study of 19,947 individuals. The Tromsø study

In recent years, a connection between depression and inflammation has been established, with a range of immunological changes, both cellular and humoral, presenting during depressive states (Beydoun et al., 2016; Haapakoski et al., 2015; Wium-Andersen et al., 2013). Furthermore, there seems to be a dose-response relationship between depression and inflammation, in the sense that the more severe the depression, the higher the level of systemic inflammation markers, most notably expressed as elevated levels of C-reactive protein (CRP) in peripheral blood (Kohler-Forsberg et al., 2017). Accordingly, CRP has been suggested as a marker of depression severity and depression subtypes, as well as an indicator of specific symptom profiles (Jokela et al., 2016). Furthermore, inflammation has been suggested as a target for treatment with immunomodulatory drugs (Alexopoulos and Morimoto, 2011; Kohler et al., 2014). However, the research populations are predominantly younger adults, mainly in clinical settings, and there are few community-based studies providing comparative analyses of age-groups, or focusing specifically on the older population. For those that do, the results are inconsistent, as some demonstrate an association between CRP and depression (Bondy et al., 2021; Sonsin-Diaz et al., 2020; White et al., 2017), while others do not (Baune et al., 2012; Bremmer et al., 2008; Eurelings et al., 2015; Penninx et al., 2003). Thus, it is still unclear whether the inflammation in depression unfolds to the same extent in depressed older adults as in younger adults, and how the severity of the depression relates to inflammation in different age groups

Increased complement activation 3 to 6 h after trauma is a predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome: a prospective observational study

Background Complement activation is a central mechanism in systemic inflammation and remote organ dysfunction following major trauma. Data on temporal changes of complement activation early after injury is largely missing. We aimed to describe in detail the kinetics of complement activation in individual trauma patients from admission to 10 days after injury, and the association with trauma characteristics and outcome. Methods In a prospective cohort of 136 trauma patients, plasma samples obtained with high time resolution (admission, 2, 4, 6, 8 h, and thereafter daily) were assessed for terminal complement complex (TCC). We studied individual TCC concentration curves and calculated a summary measure to obtain the accumulated TCC response 3 to 6 h after injury (TCC-AUC3–6). Correlation analyses and multivariable linear regression analyses were used to explore associations between individual patients’ admission TCC, TCC-AUC3–6, daily TCC during the intensive care unit stay, trauma characteristics, and predefined outcome measures. Results TCC concentration curves showed great variability in temporal shapes between individuals. However, the highest values were generally seen within the first 6 h after injury, before they subsided and remained elevated throughout the intensive care unit stay. Both admission TCC and TCC-AUC3–6 correlated positively with New Injury Severity Score (Spearman’s rho, p-value 0.31, 0.0003 and 0.21, 0.02) and negatively with admission Base Excess (− 0.21, 0.02 and − 0.30, 0.001). Multivariable analyses confirmed that deranged physiology was an important predictor of complement activation. For patients without major head injury, admission TCC and TCC-AUC3–6 were negatively associated with ventilator-free days. TCC-AUC3–6 outperformed admission TCC as a predictor of Sequential Organ Failure Assessment score at day 0 and 4. Conclusions Complement activation 3 to 6 h after injury was a better predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome than admission TCC. Our data suggest that the greatest surge of complement activation is found within the first 6 h after injury, and we argue that this time period should be in focus in the design of future experimental studies and clinical trials using complement inhibitors.publishedVersio

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

This is the pre-peer reviewed version of the following article: Hardersen, R., Enebakk, T., Christiansen, D., Bergseth, G., Brekke, L.-O., Mollnes, T.E., ... Hovland, A.W. (2018). 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. Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), 126(4), 342-352, which has been published in final form at https://doi.org/10.1111/apm.12821. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.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

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

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

Blood transcriptome analysis of septic patients reveals a long non-coding Alu-RNA in the complement C5a receptor 1 gene

publishedVersio