Lars Heggelund

Mechanism of complement activation and its role in the inflammatory response after thoracoabdominal aortic aneurysm repair

Background—Complement activation contributes to ischemia-reperfusion injury. Patients undergoing thoracoabdominal aortic aneurysm (TAAA) repair suffer extensive ischemia-reperfusion and considerable systemic inflammation. Methods and Results—The degree and mechanism of complement activation and its role in inflammation were investigated in 19 patients undergoing TAAA repair. Patients undergoing open infrarenal aortic surgery (n=5) or endovascular descending aortic aneurysm repair (n=6) served as control subjects. Substantial complement activation was seen in TAAA patients but not in controls. C1rs-C1-inhibitor complexes increased moderately, whereas C4bc, C3bBbP, C3bc, and the terminal SC5b-9 complex (TCC) increased markedly after reperfusion, reaching a maximum 8 hours after reperfusion. Interleukin (IL)-1&bgr;, tumor necrosis factor &agr; (TNF-&agr;), and IL-8 increased significantly in TAAA patients but not in controls, peaking at 24 hours postoperatively and correlating closely with the degree of complement activation. IL-6 and IL-10 increased to a maximum 8 hours after reperfusion in the TAAA patients, were not correlated with complement activation, and increased moderately in the control subjects. Myeloperoxidase and lactoferrin increased markedly before reperfusion in all groups, whereas sICAM-1, sP-selectin, and sE-selectin were unchanged. No increase was observed in complement activation products, IL-1&bgr;, TNF-&agr;, or IL-8 in a mannose-binding lectin (MBL)–deficient TAAA patient, whereas IL-6, IL-10, myeloperoxidase, and lactoferrin increased as in the controls. Two other MBL-deficient TAAA patients receiving plasma attained significant MBL levels and showed complement and cytokine patterns identical to the MBL-sufficient TAAA patients. Conclusions—The data suggest that complement activation during TAAA repair is MBL mediated, amplified through the alternative pathway, and responsible in part for the inflammatory response.

Increased Expression of Toll-Like Receptor 2 on Monocytes in HIV Infection: Possible Roles in Inflammation and Viral Replication

BACKGROUND Toll-like receptors (TLRs) are key pattern-recognition receptors of the innate immune system, but their role in human immunodeficiency virus (HIV) infection is largely unknown. METHODS In the present study, we examined the expression of TLR2 and TLR4 on monocytes from 48 HIV-infected patients and 21 healthy control subjects by flow cytometry. RESULTS We found that freshly isolated monocytes from HIV-infected patients displayed enhanced expression of TLR2 but not TLR4, that TLR2 expression on the surface of monocytes was significantly increased upon stimulation of HIV type 1 envelope protein gp120, and that TLR2 stimulation in HIV-infected patients induced increased viral replication and TNF- alpha response. CONCLUSION Our findings suggest potential roles for TLR2 in chronic immune activation and viral replication in HIV infection.

Common variable immunodeficiency and the complement system; low mannose-binding lectin levels are associated with bronchiectasis.

The importance of the innate immune system, including mannose‐binding lectin and the complement system, in common variable immunodeficiency is unclear. The objective of this study was to evaluate mannose‐binding lectin and the complement system in relation to clinical and immunological parameters in patients with common variable immunodeficiency. Circulating levels of mannose‐binding lectin, complement components, complement activation products and functional capacity of complement pathways were correlated to clinical features within 71 patients and compared with 30 healthy controls. The main findings were; the patients had signs of increased complement activation significantly associated with signs of autoimmunity and immunological hyperactivity; there were no signs of deficiencies of the classical and alternative complement pathways in the patient group; the prevalence of lectin pathway deficiency was the same in patients and controls, but patients with increased frequency of lower respiratory tract infections or bronchiectasis had lower capacity of the lectin pathway than patients without these features (P = 0·002 and 0·004, respectively); the serum concentration of mannose‐binding lectin was inversely correlated to the frequency of lower respiratory tract infections (P = 0·002) and bronchiectasis (P = 0·01). We conclude that patients with common variable immunodeficiency have no increased frequency of complement deficiencies but signs of increased complement activation. Our findings suggest that mannose‐binding lectin and the lectin complement pathway may protect against lower respiratory tract infection and bronhiectasis in patients with common variable immunodeficiency.

Decreased serum lipocalin-2 levels in human immunodeficiency virus-infected patients: increase during highly active anti-retroviral therapy

Although neutrophil gelatinase‐associated lipocalin (NGAL) may play a pivotal role in the innate immune response, there are currently no data on NGAL levels in human immunodeficiency virus (HIV)‐infected patients. In this study we aimed to examine the regulation of NGAL in HIV infection. The regulation of NGAL in HIV infection was examined by different experimental approaches, including studies in peripheral blood and mononuclear cells (MNC) from bone marrow aspirates before and during highly active anti‐retroviral therapy (HAART). We found that: before initiating HAART, HIV‐infected patients (n = 37) had significantly decreased serum NGAL levels compared with healthy controls (n = 26); (ii) during HAART, there was a gradual and significant increase in NGAL concentrations reaching levels comparable to those in healthy controls after 12 months; (iii) this increase was seen primarily in virological responders to HAART (HIV RNA level <200 copies/ml after 24 months); (iv) phytohaemagglutinin‐stimulated NGAL release in MNC cells from bone marrow aspirates was decreased in untreated HIV‐infected patients compared with healthy controls, but increased after 26 weeks on HAART; and (v) there was a significant positive correlation between neutrophil counts and NGAL levels at all time‐points during HAART. We have shown decreased NGAL levels in HIV‐infected patients, potentially reflecting decreased number and function of neutrophils as well as impaired bone marrow myelopoiesis. These abnormalities were reversed by successful HAART. Our findings underscore further the involvement of neutrophils and innate immunity in HIV‐related immunodeficiency.

Raised serum levels of interleukin-18 is associated with disease progression and may contribute to virological treatment failure in HIV-1-infected patients

To gain further insight into the possible role of interleukin (IL)‐18 in HIV‐1 infection we examined serum levels of IL‐18 in various clinical and immunological stages of HIV‐1 infection during cross‐sectional (n = 41) and longitudinal testing (n = 20) and during HAART (n = 21, 24 months follow‐up). Our main findings were that HIV‐1‐infected patients had significantly raised IL‐18 levels comparing healthy controls, particularly in those with advanced disease, that while HAART induced a marked decline in IL‐18, virological treatment failure was associated with persistently raised IL‐18 levels during such therapy and that our in vitro experiments showed an IL‐18‐mediated up‐regulation of the HIV‐1 coreceptor CXCR4 and the pro‐apoptotic mediator TRAIL in PBMC from HIV‐1‐infected patients receiving HAART. HIV‐1 infection appears to be characterized by persistently raised IL‐18 levels and during HAART, such a pattern was associated with virological treatment failure, possibly contributing to immunodeficiency and HIV‐1 replication in these patients.

Etiology of community-acquired pneumonia and diagnostic yields of microbiological methods: a 3-year prospective study in Norway

BackgroundDespite recent advances in microbiological techniques, the etiology of community-acquired pneumonia (CAP) is still not well described. We applied polymerase chain reaction (PCR) and conventional methods to describe etiology of CAP in hospitalized adults and evaluated their respective diagnostic yields.Methods267 CAP patients were enrolled consecutively over our 3-year prospective study. Conventional methods (i.e., bacterial cultures, urinary antigen assays, serology) were combined with nasopharyngeal (NP) and oropharyngeal (OP) swab samples analyzed by real-time quantitative PCR (qPCR) for Streptococcus pneumoniae, and by real-time PCR for Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis and 12 types of respiratory viruses.ResultsEtiology was established in 167 (63%) patients with 69 (26%) patients having ≥1 copathogen. There were 75 (28%) pure bacterial and 41 (15%) pure viral infections, and 51 (19%) viral–bacterial coinfections, resulting in 126 (47%) patients with bacterial and 92 (34%) patients with viral etiology. S. pneumoniae (30%), influenza (15%) and rhinovirus (12%) were most commonly identified, typically with ≥1 copathogen. During winter and spring, viruses were detected more frequently (45%, P=.01) and usually in combination with bacteria (39%). PCR improved diagnostic yield by 8% in 64 cases with complete sampling (and by 15% in all patients); 5% for detection of bacteria; 19% for viruses (P=.04); and 16% for detection of ≥1 copathogen. Etiology was established in 79% of 43 antibiotic-naive patients with complete sampling. S. pneumoniae qPCR positive rate was significantly higher for OP swab compared to NP swab (P<.001). Positive rates for serology were significantly higher than for real-time PCR in detecting B. pertussis (P=.001) and influenza viruses (P<.001).ConclusionsEtiology could be established in 4 out of 5 CAP patients with the aid of PCR, particularly in diagnosing viral infections. S. pneumoniae and viruses were most frequently identified, usually with copathogens. Viral–bacterial coinfections were more common than pure infections during winter and spring; a finding we consider important in the proper management of CAP. When swabbing for qPCR detection of S. pneumoniae in adult CAP, OP appeared superior to NP, but this finding needs further confirmation.Trial registrationClinicalTrials.gov Identifier: NCT01563315.

Homeostatic chemokines CCL19 and CCL21 promote inflammation in human immunodeficiency virus‐infected patients with ongoing viral replication

CCL19 and CCL21 and their receptor CCR7 are expressed constitutively within lymphoid organs, regulating lymphocyte homing. Recent studies suggest that these chemokines may have inflammatory properties. We hypothesized a role of CCL19/CCL21 in human immunodeficiency virus (HIV) infection by promoting inflammation. We examined the expression of CCL19 and CCL21 in mononuclear cells from peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) in HIV‐infected patients before and during highly active anti‐retroviral therapy (HAART). We also examined the ability of CCL19/CCL21 to promote inflammatory responses in these patients. PBMC from untreated HIV‐infected patients (n = 29) released enhanced levels of CCL19 spontaneously compared with cells from controls (n = 20), particularly in those with symptomatic disease (n = 15, P < 0·01 versus controls). During HAART (n = 9), there was a decrease in the spontaneous CCL19 release and an increase in the phytohaemagglutinin‐stimulated CCL19 release in both PBMC (P < 0·01) and BMMC (P < 0·05). In patients with enhanced HIV replication there was an increased proportion of inflammatory CD8+CCR7‐CD45RA‐ T cells in peripheral blood [P < 0·01 and P < 0·05 versus controls, untreated (n = 9) and treatment failure (n = 8), respectively]. In vitro, CCL19/CCL21 promoted an inflammatory response in PBMC when accompanied by high viral load, irrespective of HAART. The HIV‐tat protein significantly boosted the inflammatory effect of CCL19/CCL21 in PBMC. These findings link a dysregulated CCL19/CCL21/CCR7 system in HIV‐infected patients to persistent inflammation and HIV replication, not only in untreated HIV infection, but also in treatment failure during HAART.

Chemokines in Children With Heterozygous Familiar Hypercholesterolemia: Selective Upregulation of RANTES

Objective—Increasing data support the involvement of chemokines in atherogenesis. However, although several studies have shown increased chemokine levels in adult patients, the literature is virtually devoid of data on chemokines in children with hypercholesterolemia. Methods and Results—We examined the gene expression of chemokines in peripheral blood mononuclear cells (PBMCs) from clinically healthy children with and without heterozygous familial hypercholesterolemia (FH). Our main findings were: (1) compared with healthy controls, PBMCs from FH children showed significantly higher mRNA levels of RANTES, but not of the other examined chemokines; (2) an opposite pattern was seen in adult FH subjects, with markedly enhanced expression of macrophage inflammatory peptide-1&agr;, but not of RANTES; (3) this increased gene expression of RANTES in PBMCs from FH children seemed to reflect enhanced RANTES expression in monocytes but not in T cells; (4) FH children also had raised serum levels of neopterin, additionally suggesting monocyte/macrophage activation in these children; and (5) PBMCs from both FH children and controls showed enhanced release of interleukin 8 on RANTES stimulation in vitro. Conclusions—Our findings support a role of inflammation also in the early stages of atherogenesis possibly involving monocyte-derived RANTES as an important mediator.

Enhanced levels of the CCR7 ligands CCL19 and CCL21 in HIV infection : correlation with viral load, disease progression and response to highly active antiretroviral therapy

The CCR7 ligands, CCL19 and CCL21, coordinate lymph node homing of naive and central memory T cells. In untreated HIV-infected patients, serum levels of CCL19 and CCL21 showed a biphasic pattern during progression; a marked increase was followed by a decline in patients with advanced immunodeficiency. During highly active antiretroviral therapy, a decrease in CCL19/CCL21 levels was restricted to virologic responders. We suggest that dysregulation of CCR7 ligands may play an important role in progression of HIV infection.

Modulatory effect of mannose-binding lectin on cytokine responses: possible roles in HIV infection

Background  Mannose‐binding lectin (MBL) is a soluble receptor of the innate immune system, probably contributing to antimicrobial defence. The possible role of MBL in HIV infection is unclear.