| 1. |
- Baptista, Marisa A. P., et al.
(författare)
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Deletion of Wiskott-Aldrich syndrome protein triggers Rac2 activity and increased cross-presentation by dendritic cells
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Wiskott-Aldrich syndrome (WAS) is caused by loss-of-function mutations in the WASp gene. Decreased cellular responses in WASp-deficient cells have been interpreted to mean that WASp directly regulates these responses in WASp-sufficient cells. Here, we identify an exception to this concept and show that WASp-deficient dendritic cells have increased activation of Rac2 that support cross-presentation to CD8(+) T cells. Using two different skin pathology models, WASp-deficient mice show an accumulation of dendritic cells in the skin and increased expansion of IFN gamma-producing CD8(+) T cells in the draining lymph node and spleen. Specific deletion of WASp in dendritic cells leads to marked expansion of CD8(+) T cells at the expense of CD4(+) T cells. WASp-deficient dendritic cells induce increased cross-presentation to CD8(+) T cells by activating Rac2 that maintains a near neutral pH of phagosomes. Our data reveals an intricate balance between activation of WASp and Rac2 signalling pathways in dendritic cells.
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| 2. |
- Gallardo-Dodd, Carlos J., et al.
(författare)
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Exposure of volunteers to microgravity by dry immersion bed over 21 days results in gene expression changes and adaptation of T cells
- 2023
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Ingår i: Science Advances. - 2375-2548. ; 9:34
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Tidskriftsartikel (refereegranskat)abstract
- The next steps of deep space exploration are manned missions to Moon and Mars. For safe space missions for crew members, it is important to understand the impact of space flight on the immune system. We studied the effects of 21 days dry immersion (DI) exposure on the transcriptomes of T cells isolated from blood samples of eight healthy volunteers. Samples were collected 7 days before DI, at day 7, 14, and 21 during DI, and 7 days after DI. RNA sequencing of CD3(+) T cells revealed transcriptional alterations across all time points, with most changes occurring 14 days after DI exposure. At day 21, T cells showed evidence of adaptation with a transcriptional profile resembling that of 7 days before DI. At 7 days after DI, T cells again changed their transcriptional profile. These data suggest that T cells adapt by rewiring their transcriptomes in response to simulated weightlessness and that remodeling cues persist when reexposed to normal gravity.
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| 3. |
- Gerasimcik, Natalija, et al.
(författare)
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The Rho GTPase Cdc42 Is Essential for the Activation and Function of Mature B Cells
- 2015
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 194:10, s. 4750-4758
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Tidskriftsartikel (refereegranskat)abstract
- The Rho GTPase Cdc42 coordinates regulation of the actin and the microtubule cytoskeleton by binding and activating the Wiskott-Aldrich syndrome protein. We sought to define the role of intrinsic expression of Cdc42 by mature B cells in their activation and function. Mice with inducible deletion of Cdc42 in mature B cells formed smaller germinal centers and had a reduced Ab response, mostly of low affinity to T cell-dependent Ag, compared with wild-type (WT) controls. Spreading formation of long protrusions that contain F-actin, microtubules, and Cdc42-interacting protein 4, and assumption of a dendritic cell morphology in response to anti-CD40 plus IL-4 were impaired in Cdc42-deficient B cells compared with WT B cells. Cdc42-deficient B cells had an intact migratory response to chemokine in vitro, but their homing to the B cell follicles in the spleen in vivo was significantly impaired. Cdc42-deficient B cells induced a skewed cytokine response in CD4(+) T cells, compared with WT B cells. Our results demonstrate a critical role for Cdc42 in the motility of mature B cells, their cognate interaction with T cells, and their differentiation into Ab-producing cells.
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| 4. |
- Han, Hongya, et al.
(författare)
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Human 15-lipoxygenase-1 is a regulator of dendritic-cell spreading and podosome formation
- 2017
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Ingår i: The FASEB Journal. - : FEDERATION AMER SOC EXP BIOL. - 0892-6638 .- 1530-6860. ; 31:2, s. 491-504
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Tidskriftsartikel (refereegranskat)abstract
- Dendritic cells (DCs) involved in proinflammatory immune responses derive mainly from peripheral monocytes, and the cells subsequently mature and migrate into the inflammatory micromilieu. Here we report that suppressing of 15-lipoxygenase-1 led to a substantial reduction in DC spreading and podosome formation in vitro. The surface expression of CD83 was significantly lower in both sh-15-lipoxygenase-1 (15-LOX-1)-transduced cells and DCs cultivated in the presence of a novel specific 15-LOX-1 inhibitor. The T-cell response against tetanus-pulsed DCs was only affected to a minor extent on inhibition of 15-LOX-1. In contrast, endocytosis and migration ability of DCs were significantly suppressed on 15-LOX-1 inhibition. The expression of 15-LOX-1 in DCs was also demonstrated in affected human skin in atopic and contact dermatitis, showing that the enzyme is indeed expressed in inflammatory diseases in vivo. This study demonstrated that inhibiting 15-LOX-1 led to an impaired podosome formation in DCs, and consequently suppressed antigen uptake and migration capacity. These results indicated that 15-LOX-1 is a potential target for inhibiting the trafficking of DCs to lymphoid organs and inflamed tissues and decreasing the inflammatory response attenuating symptoms of certain immunologic and inflammatory disorders such as dermatitis.-Han, H., Liang, X., Ekberg, M., Kritikou, J. S., Brunnstro " m, angstrom., Pelcman, B., Matl, M., Miao, X., Andersson, M., Yuan, X., Schain, F., Parvin, S., Melin, E., Sjoberg, J., Xu, D., Westerberg, L. S., Bjorkholm, M., Claesson, H.- E. Human 15-lipoxygenase- 1 is a regulator of dendritic-cell spreading and podosome formation.
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| 5. |
- Brauner, Susanna, et al.
(författare)
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H1N1 vaccination in Sjogren's syndrome triggers polyclonal B cell activation and promotes autoantibody production
- 2017
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 76:10, s. 1755-1763
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesVaccination of patients with rheumatic disease has been reported to result in lower antibody titres than in healthy individuals. However, studies primarily include patients on immunosuppressive therapy. Here, we investigated the immune response of treatment-naive patients diagnosed with primary Sjogren's syndrome (pSS) to an H1N1 influenza vaccine.Methods Patients with Sjogren's syndrome without immunomodulatory treatment and age-matched and gender-matched healthy controls were immunised with an H1N1 influenza vaccine and monitored for serological and cellular immune responses. Clinical symptoms were monitored with a standardised form. IgG class switch and plasma cell differentiation were induced in vitro in purified naive B cells of untreated and hydroxychloroquine-treated patients and healthy controls. Gene expression was assessed by NanoString technology.ResultsSurprisingly, treatment-naive patients with Sjogren's syndrome developed higher H1N1 IgG titres of greater avidity than healthy controls on vaccination. Notably, off-target B cells were also triggered resulting in increased anti-EBV and autoantibody titres. Endosomal toll-like receptor activation of naive B cells in vitro revealed a greater propensity of patient-derived cells to differentiate into plasmablasts and higher production of class switched IgG. The amplified plasma cell differentiation and class switch could be induced in cells from healthy donors by preincubation with type 1 interferon, but was abolished in hydroxychloroquine-treated patients and after in vitro exposure of naive B cells to chloroquine.ConclusionsThis comprehensive analysis of the immune response in autoimmune patients to exogenous stimulation identifies a mechanistic basis for the B cell hyperactivity in Sjogren's syndrome, and suggests that caution is warranted when considering vaccination in non-treated autoimmune patients.
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| 6. |
- Dahlberg, Carin I. M., et al.
(författare)
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A Novel Mouse Model for the Hyper-IgM Syndrome : A Spontaneous Activation-Induced Cytidine Deaminase Mutation Leading to Complete Loss of Ig Class Switching and Reduced Somatic Hypermutation
- 2014
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 193:9, s. 4732-4738
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Tidskriftsartikel (refereegranskat)abstract
- We describe a spontaneously derived mouse line that completely failed to induce Ig class switching in vitro and in vivo. The mice inherited abolished IgG serum titers in a recessive manner caused by a spontaneous G -> A transition mutation in codon 112 of the aicda gene, leading to an arginine to histidine replacement (AID(R112H)). Ig class switching was completely reconstituted by expressing wild-type AID. Mice homozygous for AID(R112H) had peripheral B cell hyperplasia and large germinal centers in the absence of Ag challenge. Immunization with SRBCs elicited an Ag-specific IgG1 response in wild-type mice, whereas AID(R112H) mice failed to produce IgG1 and had reduced somatic hypermutation. The phenotype recapitulates the human hyper-IgM (HIGM) syndrome that is caused by point mutations in the orthologous gene in humans, and the AID(R112H) mutation is frequently found in HIGM patients. The AID(R112H) mouse model for HIGM provides a powerful and more precise tool than conventional knockout strategies.
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| 7. |
- Record, Julien, et al.
(författare)
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Journey to the Center of the Cell : Cytoplasmic and Nuclear Actin in Immune Cell Functions
- 2021
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Ingår i: Frontiers in Cell and Developmental Biology. - : Frontiers Media SA. - 2296-634X. ; 9
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Forskningsöversikt (refereegranskat)abstract
- Actin cytoskeletal dynamics drive cellular shape changes, linking numerous cell functions to physiological and pathological cues. Mutations in actin regulators that are differentially expressed or enriched in immune cells cause severe human diseases known as primary immunodeficiencies underscoring the importance of efficienct actin remodeling in immune cell homeostasis. Here we discuss recent findings on how immune cells sense the mechanical properties of their environement. Moreover, while the organization and biochemical regulation of cytoplasmic actin have been extensively studied, nuclear actin reorganization is a rapidly emerging field that has only begun to be explored in immune cells. Based on the critical and multifaceted contributions of cytoplasmic actin in immune cell functionality, nuclear actin regulation is anticipated to have a large impact on our understanding of immune cell development and functionality.
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