Børre Fevang

Enhanced Expression of the Homeostatic Chemokines CCL19 and CCL21 in Clinical and Experimental Atherosclerosis. Possible Pathogenic Role in Plaque Destabilization

Objective—Based on their role in T-cell homing into nonlymphoid tissue, we examined the role of the homeostatic chemokines CCL19 and CCL21 and their common receptor CCR7 in coronary artery disease (CAD). Methods and Results—We performed studies in patients with stable (n=40) and unstable (n=40) angina and healthy controls (n=20), in vitro studies in T-cells and macrophages, and studies in apolipoprotein-E–deficient (ApoE−/−) mice and human atherosclerotic carotid plaques. We found increased levels of CCL19 and CCL21 within the atherosclerotic lesions of the ApoE−/− mice, in human atherosclerotic carotid plaques, and in plasma of CAD patients. Whereas strong CCR7 expression was seen in T-cells from murine and human atherosclerotic plaques, circulating T-cells from angina patients showed decreased CCR7 expression. CCL19 and CCL21 promoted an inflammatory phenotype in T-cells and macrophages and increased matrix metalloproteinase (MMP) and tissue factor levels in the latter cell type. Although aggressive statin therapy increased CCR7 and decreased CCL19/CCL21 levels in peripheral blood from CAD patients, conventional therapy did not. Conclusions—The abnormal regulation of CCL19 and CCL21 and their common receptor in atherosclerosis could contribute to disease progression by recruiting T-cells and macrophages to the atherosclerotic lesions and by promoting inflammatory responses in these cells.

Low numbers of regulatory T cells in common variable immunodeficiency: association with chronic inflammation in vivo

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by defective immunoglobulin production and high frequency of bacterial infections, autoimmunity and manifestations of chronic inflammation. Abnormalities of CD4+CD25highforkhead box P3 (FoxP3)+ regulatory T cells (Treg) have been associated with autoimmune and inflammatory disorders, and we hypothesized that CVID might be characterized by Treg abnormalities. CD3+ cells from patients and controls were analysed for the expression of FoxP3 mRNA by real time reverse transcription–polymerase chain reaction (RT–PCR). Peripheral blood mononuclear cells from CVID patients and controls were stained for Treg markers, analysed by flow cytometry and compared to clinical characteristics. The main findings were: (i) CVID patients had significantly decreased expression of FoxP3 mRNA and decreased proportions of CD4+CD25highFoxP3+ cells compared to controls; (ii) CVID patients with splenomegaly had even lower proportions of Treg compared to other patients and controls; (iii) serum levels of the inflammatory marker neopterin were correlated negatively with the proportions of Treg within the CVID population, while there was no significant association with bronchiectasis. We have demonstrated decreased proportions of Treg in CVID patients, particularly in those with signs of chronic inflammation. Decreased proportions of TReg are suggested to be pathogenetically important in autoimmunity, and our results suggest that TReg may have a similar role in CVID.

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.

High levels and inflammatory effects of soluble CXC ligand 16 (CXCL16) in coronary artery disease: down-regulatory effects of statins

AIMS CXC ligand 16 (CXCL16) may be involved in inflammation and lipid metabolism, and we hypothesized a role for this chemokine in coronary artery disease (CAD). METHODS AND RESULTS We performed clinical studies in CAD patients as well as experimental studies in cells with relevance to atherogenesis [i.e. endothelial cells, vascular smooth muscle cells (SMC), and peripheral blood mononuclear cells (PBMC)]. We also examined the ability of HMG-CoA reductase inhibitors (statins) to modulate CXCL16 levels both in vivo and in vitro. Our main findings were: (i) patients with stable (n = 40) and unstable (n = 40) angina had elevated plasma levels of CXCL16 compared with controls (n = 20); (ii) low-dose simvastatin (20 mg qd, n = 15) and high-dose atorvastatin (80 mg qd, n = 9) down-regulated plasma levels of CXCL16 during 6 months of therapy; (iii) in vitro, atorvastatin significantly decreased the interleukin (IL)-1beta-mediated release of CXCL16 from PBMC and endothelial cells; (iv) attenuating effect of atorvastatin on the IL-1beta-mediated release of CXCL16 in PBMC seems to involve post-transcriptional modulation as well as down-regulation of CXCL16 release through inhibition of the protease a disintegrin and metalloproteinase 10 (ADAM10); (v) soluble CXCL16 increased the release of IL-8, monocyte chemoattractant peptide 1, and matrix metalloproteinases in vascular SMC and increased the release of IL-8 and monocyte chemoattractant peptide 1 in PBMC, with particularly enhancing effects in cells from CAD patients. CONCLUSION Our findings suggest that soluble CXCL16 could be linked to atherogenesis not only as a marker of inflammation, but also as a potential inflammatory mediator.

Primary immunodeficiency diseases: Genomic approaches delineate heterogeneous Mendelian disorders

Background: Primary immunodeficiency diseases (PIDDs) are clinically and genetically heterogeneous disorders thus far associated with mutations in more than 300 genes. The clinical phenotypes derived from distinct genotypes can overlap. Genetic etiology can be a prognostic indicator of disease severity and can influence treatment decisions. Objective: We sought to investigate the ability of whole‐exome screening methods to detect disease‐causing variants in patients with PIDDs. Methods: Patients with PIDDs from 278 families from 22 countries were investigated by using whole‐exome sequencing. Computational copy number variant (CNV) prediction pipelines and an exome‐tiling chromosomal microarray were also applied to identify intragenic CNVs. Analytic approaches initially focused on 475 known or candidate PIDD genes but were nonexclusive and further tailored based on clinical data, family history, and immunophenotyping. Results: A likely molecular diagnosis was achieved in 110 (40%) unrelated probands. Clinical diagnosis was revised in about half (60/110) and management was directly altered in nearly a quarter (26/110) of families based on molecular findings. Twelve PIDD‐causing CNVs were detected, including 7 smaller than 30 Kb that would not have been detected with conventional diagnostic CNV arrays. Conclusion: This high‐throughput genomic approach enabled detection of disease‐related variants in unexpected genes; permitted detection of low‐grade constitutional, somatic, and revertant mosaicism; and provided evidence of a mutational burden in mixed PIDD immunophenotypes.

Activating PI3Kδ mutations in a cohort of 669 patients with primary immunodeficiency.

The gene PIK3CD codes for the catalytic subunit of phosphoinositide 3‐kinase δ (PI3Kδ), and is expressed solely in leucocytes. Activating mutations of PIK3CD have been described to cause an autosomal dominant immunodeficiency that shares clinical features with common variable immunodeficiency (CVID). We screened a cohort of 669 molecularly undefined primary immunodeficiency patients for five reported mutations (four gain‐of‐function mutations in PIK3CD and a loss of function mutation in PIK3R1) using pyrosequencing. PIK3CD mutations were identified in three siblings diagnosed with CVID and two sporadic cases with a combined immunodeficiency (CID). The PIK3R1 mutation was not identified in the cohort. Our patients with activated PI3Kδ syndrome (APDS) showed a range of clinical and immunological findings, even within a single family, but shared a reduction in naive T cells. PIK3CD gain of function mutations are more likely to occur in patients with defective B and T cell responses and should be screened for in CVID and CID, but are less likely in patients with a pure B cell/hypogammaglobulinaemia phenotype.

Development of pulmonary abnormalities in patients with common variable immunodeficiency: associations with clinical and immunologic factors

BACKGROUND Patients with common variable immunodeficiency (CVID) have low serum IgG, IgA, and/or IgM levels and recurrent airway infections. Radiologic pulmonary abnormalities and impaired function are common complications. It is unclear to what extent IgG replacement treatment prevents further pulmonary damage and how factors beside infections may contribute to progression of disease. OBJECTIVES To study the development of pulmonary damage and determine how clinical and immunologic factors, such as serum IgG, may contribute to possible changes. METHODS In a retrospective, longitudinal study of 54 patients with CVID already treated with immunoglobulins, we examined changes of lung function and findings on high-resolution computed tomography (HRCT), obtained at 2 time points (the date of the last pulmonary function measurement before April 2005 [T1] and the date of the measurement performed closest to 5 years earlier [T0]) 2 to 7 years apart and explored possible relations to clinical and immunologic factors such as levels of IgG, tumor necrosis alpha (TNF-alpha), and mannose-binding lectin (MBL) in serum. RESULTS Despite a mean (SD) serum IgG level of 7.6 (2.3) g/L for all the patients during the entire study period, lung function decreased from T0 to T1. The combination of a low serum IgA level and serum MBL was associated with the presence of bronchiectasis and lower lung function and with worsening of several HRCT abnormalities from T0 to T1. Increased serum levels of TNF-alpha were related to deterioration of gas diffusion. A mean serum IgG level less than 5 g/L between T0 and T1 was associated with worsening of linear and/or irregular opacities seen on HRCT. CONCLUSION For a period of 4 years, lung function and HRCT deteriorated in CVID patients treated with immunoglobulins.

Association of CLEC16A with human common variable immunodeficiency disorder and role in murine B cells.

Common variable immunodeficiency disorder (CVID) is the most common symptomatic primary immunodeficiency in adults, characterized by B cell abnormalities and inadequate antibody response. CVID patients have considerable autoimmune comorbidity and we therefore hypothesized that genetic susceptibility to CVID may overlap with autoimmune disorders. Here, in the largest genetic study performed in CVID to date, we compare 778 CVID cases with 10,999 controls across 123,127 single nucleotide polymorphisms (SNPs) on the Immunochip. We identify the first non-HLA genome-wide significant risk locus at CLEC16A (rs17806056, P=2.0×10−9) and confirm the previously reported human leukocyte antigen (HLA) associations on chromosome 6p21 (rs1049225, P =4.8×10−16). Clec16a knock down (KD) mice showed reduced number of B cells and elevated IgM levels compared to controls, suggesting that CLEC16A may be involved in immune regulatory pathways of relevance to CVID. In conclusion, the CLEC16A associations in CVID represent the first robust evidence of non-HLA associations in this immunodeficiency condition.

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.

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.