| 1. |
- Berggren, Olof
(författare)
-
Regulation of Type I Interferon Production in Plasmacytoid Dendritic Cells : Effect of Genetic Factors and Interactions with NK Cells and B Cells
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The type I interferon (IFN) system plays a central role in the etiopathogenesis of many autoimmune diseases, e.g. systemic lupus erythematosus (SLE). Activation of the type I IFN system in SLE is promoted by endogenous nucleic acid-containing immune complexes (ICs) which stimulate plasmacytoid dendritic cells (pDCs). This thesis focuses on the regulation of IFN-α production in pDCs, by interactions with B cells and natural killer (NK) cells, and by genetic factors.In Study I, RNA-IC-stimulated CD56dim NK cells were found to be activated via FcγRIIIa and enhanced the IFN-α production by pDCs. The enhancing effect of the NK cells was mediated via both soluble factors, such as the cytokine MIP-1β, and in a cell-cell contact mediated manner via the adhesion molecule LFA-1. In Study II, B cells enhanced the IFN-α production by pDCs via cell-cell contact or soluble factors, depending on the stimuli. The cell-cell contact-mediated enhancement, when the cells were stimulated with RNA-IC, was abolished by blocking the cell adhesion molecule CD31. B cells stimulated with the oligonucleotide ODN2216 enhanced the IFN-α production via soluble factors. In Study III, gene variants related to autoimmune or inflammatory diseases were analyzed for the association to the IFN-α production by pDCs, alone or in coculture with NK or B cells. Depending on cell combination, 18-86 SNPs (p < 0.001) were associated with the IFN-α production. Several of the SNPs showed novel associations to the type I IFN system, while some loci have been described earlier for their association with SLE, e.g. IL10 and PXK. In Study IV, several B cell populations were affected by cocultivation with pDCs and stimulation with RNA-IC. The frequency of CD24hiCD38hi B cells of regulatory character was increased in the pDC-B cell cocultures. However, RNA-IC-stimulation only induced modest levels of IL-10. A remarkably increased frequency of double negative CD27-IgD- B cells was found in the RNA-IC-stimulated cocultures of pDCs and B cells.In conclusion, the findings in the present thesis reveal novel mechanisms behind the regulation of the type I IFN system which could be important targets in autoimmune diseases with constantly activated pDCs.
|
|
| 2. |
- Hagberg, Niklas, 1977-
(författare)
-
The Role of Plasmacytoid Dendritic Cells and Natural Killer Cells in Systemic Lupus Erythematosus
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production, which can eventually lead to immune complex (IC)-mediated organ damage. Due to the stimulation of plasmacytoid dendritic cells (pDC) by nucleic acid-containing ICs (DNA- or RNA-IC), patients with SLE have an ongoing interferon (IFN)-α production. IFN-α induces a general activation of the immune system that may initiate or propagate an autoimmune process if not properly regulated. Previous studies have shown that natural killer (NK) cells potently enhance the IFN-α production by pDCs.In study I, the mechanisms behind the NK cell-mediated increased IFN-α production by RNA-IC-stimulated pDCs were investigated. ICs triggered CD56dim NK cells via FcγRIIIA to the secretion of cytokines (e.g. MIP-1β) that promoted IFN-α production. Additionally, an LFA-1-dependent cell-cell interaction between pDCs and NK cells strongly contributed to the increased production of IFN-α. In study II, the RNA-IC-induced regulation of surface molecules on pDCs and NK cells was investigated. The expression of CD319 and CD229, which are two SLAM family receptors genetically associated with SLE, was induced on pDCs and NK cells by RNA-IC. IFN-α-producing pDCs displayed an increased expression of CD319 and CD229, whereas pDCs from patients with SLE had a decreased expression of CD319. In study III, we serendipitously identified an SLE patient harboring autoantibodies to the NK cell receptor CD94/NKG2A. In study IV, sera from 203 patients with SLE were analyzed for autoantibodies to the CD94/NKG2A, CD94/NKG2C and NKG2D receptors. Seven patients harbored anti-CD94/NKG2A autoantibodies, and two of these patient’s autoantibodies also reacted with CD94/NKG2C. Anti-CD94/NKG2A and anti-CD94/NKG2C autoantibodies both interfered with the HLA-E-mediated regulation of NK cell cytotoxicity, and facilitated the elimination of target cells expressing these receptors. Furthermore, these autoantibodies were found in a group of severely diseased SLE patients and their titers closely followed disease activity.In conclusion, this thesis provides insights to molecular mechanisms whereby NK cells regulate the IFN-α production, it further links the SLAM receptors to SLE, and it describes novel autoantibodies to receptors regulating NK cell cytotoxicity. Together these findings strengthen the assumption that NK cells are involved in the pathogenesis of SLE.
|
|
| 3. |
- Hjorton, Karin, 1974-
(författare)
-
The activation and regulation of plasmacytoid dendritic cells in SLE : and possible therapeutic interventions
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic Lupus Erythematosus (SLE) is an autoimmune disease, characterized by the presence of anti-nuclear antibodies and the formation of nucleic acid containing immune complexes (ICs), which can cause organ damage by deposition in tissues. ICs strongly trigger the plasmacytoid dendritic cells (pDCs) to produce interferon (IFN)-α, which potently activates the immune system. An activated type I IFN system is seen in a majority of SLE patients. Natural killer (NK) cells enhance the IC triggered response of pDCs. Other NK cell alterations are described in SLE. Standard SLE treatment, hydroxychloroquine (HCQ), reduces flare risks, and HCQ concentration measurement can optimize its dosing. However, new treatments are needed.In paper I, we screened for autoantibodies to lectin-like NK cell receptors. In 3.4% of SLE patient sera, autoantibodies to CD94/NKG2A and CD94/NKG2C were found, which interfered with HLA-E mediated regulation of NK cell cytotoxicity, and facilitated elimination of target cells expressing expressing these receptors. Autoantibody levels correlated with SLE disease activity and with a more severe disease phenotype.In paper II, we found that RNA-IC triggered proinflammatory cytokine production in immune cells from healthy blood donors and SLE patients. After RNA-IC stimulation of pDCs, RNA sequencing detected 975 differentially expressed genes, connected to cytokine pathways, cell regulation and apoptosis. An IRAK4i had a broader inhibitory effect on RNA-IC triggered cytokine production and pro-inflammatory pathways than HCQ.In paper III we showed that RNA-IC induced type III IFN production in a subset of pDCs (3%) which also produced type I IFN. Type III IFN production by pDCs was enhanced by NK and B cells, as well as by IFN-λ2, IFN-α2b, interleukin (IL)-3, IL-6 and GM-CSF. Type III IFN production by RNA-IC stimulated immune cells of SLE patients was detected in a minority. IFN-α2b and GM-CSF increased the proportion of responders to RNA-IC from 11 to 33%.In paper IV a LC-HRMS method, was evaluated for HCQ concentration measurement in whole blood (WB), serum and plasma from 26 SLE patients. The levels in WB were approximately 2-fold compared to serum and plasma, and correlated with weekly HCQ-dose. Large inter-individual variations were observed, despite equal doses. The WB matrix showed superior reproducibility in patient samples (CV<5%).These findings add to the knowledge of how cytokine production by pDCs in SLE is regulated, and support a role for NK cells in the pathogenesis of SLE. Moreover WB was the superior matrix for HCQ measurement in SLE patients.
|
|
| 4. |
- Leonard, Dag, 1975-
(författare)
-
Cardiovascular Disease and Immune Mechanisms in Systemic Lupus Erythematosus
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune, inflammatory disease characterized by autoantibody production and an activated type I interferon system. Cardiovascular disease (CVD) is as a major cause of morbidity and mortality. The aim of this thesis was to identify genetic risk factors for CVD in SLE. The role of T cells in regulation of the interferon-α (IFNα) production by plasmacytoid dendritic cells (pDCs) was also investigated. In paper I, a thicker intima, thinner media and increased intima/media ratio was found in young premenopausal women with SLE compared to healthy controls indicating increased cardiovascular risk. As traditional ultrasound assessment of the common carotid intima-media thickness (CCA-IMT) in SLE has given conflicting results separate measurement of the intima and media can be a useful tool to identify SLE patients at increased risk of CVD. In paper II, an association was demonstrated in SLE between a STAT4 risk allele and ischemic cerebrovascular disease and presence of anti-phospholipid antibodies (aPL). The association remained after adjustment for traditional CVD risk factors. A possible mechanism for this association is that the risk allele leads to increased production of aPL, which promotes thromboembolism. In paper III, a genetic locus in IRF8 was identified to be associated to coronary heart disease (CHD) in SLE. The association remained after adjustment of other CHD risk factors. Patients with the IRF8 risk variant had increased CCA-IMT, more carotid plaques and reduced frequency of circulating B cells. Weaker binding of nuclear protein to the risk allele was demonstrated, suggesting a regulatory function of the IRF8 risk variant. In paper IV, activated T cells were found to strongly enhance the IFNα production by pDC stimulated with RNA-containing immune complexes via GM-CSF and IL-3. Activated SLE T cells enhanced the IFNα production to the same extent as T cells from healthy controls. This finding together with previous observations in SLE of increased levels of GM-CSF and IL-3 suggests that T cells contribute to the activated type I interferon system in SLE. In conclusion, this thesis demonstrates that genetic predisposition is important for CVD in SLE and describes a new role for T cells in the pathogenesis of SLE.
|
|
| 5. |
- Lövgren, Tanja, 1976-
(författare)
-
Endogenous Type I Interferon Inducers in Systemic Autoimmune Diseases
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Patients with systemic lupus erythematosus (SLE) have elevated levels of interferon (IFN)-α in blood and IFN-α-producing cells in tissues. In the present thesis, we investigate the mechanisms behind the upregulated IFN-α-production in SLE and also show that the IFN-α system is activated in primary Sjögren’s syndrome (pSS), with IFN-α-producing cells in the major affected organ, the salivary glands. The IFN-α is a type I IFN, a family of cytokines counteracting especially viral infections, by acting directly on infected cells, and via many immunomodulatory effects. The latter may also contribute to autoimmune processes.The type I IFNs are usually produced upon recognition of microbial structures. In SLE, however, DNA-containing immune complexes (ICs) that induce IFN-α production are found. Many autoantibodies in SLE and pSS are directed to nucleic acids or to DNA/RNA-binding proteins. We show that also RNA in complex with autoantibodies from SLE or pSS patients (RNA-IC) induces IFN-α-production. The RNA could be either in the form of RNA-containing material released from apoptotic or necrotic cells or as a pure RNA-containing autoantigen, the U1 small nuclear ribonucleoprotein particle. The IFN-α-production induced by RNA-IC occurred in plasmacytoid dendritic cells (PDCs), also termed natural IFN-producing cells (NIPCs), via binding to Fcγ-receptor IIa, endocytosis and triggering of Toll-like receptors (TLRs), probably TLR7 and TLR9. The RNA-IC may also have other effects, and we found that they induce prostaglandin E2 (PGE2) production in monocytes and tumor necrosis factor (TNF)-α in both monocytes and NIPC/PDC. The PGE2 downregulated the IFN-α induction in NIPC/PDC, and the IFN-α induction was increased in monocyte-depleted cell cultures. The findings presented in this thesis aids in the understanding of the mechanisms behind the activated IFN-α system in SLE and other autoimmune diseases, and shows that also pSS is one of these diseases.
|
|
