| 1. |
- Blom, Anna M, et al.
(författare)
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A Novel Non-Synonymous Polymorphism (p.Arg240His) in C4b-Binding Protein Is Associated with Atypical Hemolytic Uremic Syndrome and Leads to Impaired Alternative Pathway Cofactor Activity.
- 2008
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Ingår i: Journal of Immunology. - 1550-6606. ; 180:9, s. 6385-6391
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Tidskriftsartikel (refereegranskat)abstract
- Atypical hemolytic uremic syndrome (aHUS) is a disorder characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. Mutations, polymorphisms, and copy number variation in complement factors and inhibitors are associated with aHUS. In this study, we report the first functional non-synonymous polymorphism in the complement inhibitor C4b-binding protein (C4BP) alpha-chain (c.719G>A; p.Arg240His), which is associated with aHUS. This heterozygous change was found in 6/166 aHUS patients compared with 5/542 normal (chi2 = 6.021; p = 0.014), which was replicated in a second cohort of aHUS patients in which we found 5/170 carriers. The polymorphism does not decrease expression efficiency of C4BP. p.Arg240His is equally efficient as the wild type in binding and supporting degradation of C4BP but its ability to bind C3b and act as cofactor to its degradation both in fluid phase and on surfaces is impaired. This observation supports the hypothesis that dysregulation of the alternative pathway of complement is pivotal for aHUS. Three of the patients carry also mutations in membrane cofactor protein and factor H strengthening the hypothesis that individuals may carry multiple susceptibility factors with an additive effect on the risk of developing aHUS.
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| 2. |
- Duncan, Renee C., et al.
(författare)
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Identification of a Catalytic Exosite for Complement Component C4 on the Serine Protease Domain of C1s
- 2012
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 189:5, s. 2365-2373
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Tidskriftsartikel (refereegranskat)abstract
- The classical pathway of complement is crucial to the immune system, but it also contributes to inflammatory diseases when dys-regulated. Binding of the C1 complex to ligands activates the pathway by inducing autoactivation of associated C1r, after which C1r activates C1s. C1s cleaves complement component C4 and then C2 to cause full activation of the system. The interaction between C1s and C4 involves active site and exosite-mediated events, but the molecular details are unknown. In this study, we identified four positively charged amino acids on the serine protease domain that appear to form a catalytic exosite that is required for efficient cleavage of C4. These residues are coincidentally involved in coordinating a sulfate ion in the crystal structure of the protease. Together with other evidence, this pointed to the involvement of sulfate ions in the interaction with the C4 substrate, and we showed that the protease interacts with a peptide from C4 containing three sulfotyrosine residues. We present a molecular model for the interaction between C1s and C4 that provides support for the above data and poses questions for future research into this aspect of complement activation. The Journal of Immunology, 2012, 189: 2365-2373.
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| 3. |
- Duncan, Renee C., et al.
(författare)
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Multiple domains of MASP-2, an initiating complement protease, are required for interaction with its substrate C4
- 2012
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 49:4, s. 593-600
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Tidskriftsartikel (refereegranskat)abstract
- The complement system is fundamental to both innate and adaptive immunity and can be initiated via the classical, lectin or alternative pathways. Cleavage of C4 by MASP-2, the initiating protease of the lectin pathway, is a crucial event in the activation of this pathway, preceding the eventual formation of the C3 convertase (C4bC2a) complex on the pathogen surface. Interactions required for the cleavage of C4 by MASP-2 are likely to be facilitated by the initial binding of C4 to an exosite on the protease. We have shown that both proteolytically active and catalytically inactive CCP1-CCP2-serine protease (CCP1-CCP2-SP) forms bind C4 with similar affinity. Interestingly, proteins containing the CCP1-CCP2 domains or the SP domain alone bound C4 with much lower affinity than the CCP1-CCP2-SP protein, suggesting that the CCP domains cooperate positively with the active site to mediate efficient binding and cleavage of C4. In addition, mutation of residue K342 to alanine in the CCP1 domain abolished binding to both C4 and C4b in its CCP1-CCP2 form, suggesting a key electrostatic role for this amino acid. The presented data indicates that all of the domains are required in order to mediate high affinity interaction with C4. (C) 2011 Elsevier Ltd. All rights reserved.
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| 4. |
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| 5. |
- Felberg, Anna, et al.
(författare)
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Elevated expression of complement factor I in lung cancer cells associates with shorter survival–Potentially via non-canonical mechanism
- 2024
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Ingår i: Translational Research. - 1931-5244. ; 269, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- While numerous membrane-bound complement inhibitors protect the body's cells from innate immunity's autoaggression, soluble inhibitors like complement factor I (FI) are rarely produced outside the liver. Previously, we reported the expression of FI in non-small cell lung cancer (NSCLC) cell lines. Now, we assessed the content of FI in cancer biopsies from lung cancer patients and associated the results with clinicopathological characteristics and clinical outcomes. Immunohistochemical staining intensity did not correlate with age, smoking status, tumor size, stage, differentiation grade, and T cell infiltrates, but was associated with progression-free survival (PFS), overall survival (OS) and disease-specific survival (DSS). Multivariate Cox analysis of low vs. high FI content revealed HR 0.55, 95 % CI 0.32-0.95, p=0.031 for PFS, HR 0.51, 95 % CI 0.25-1.02, p=0.055 for OS, and HR 0.32, 95 % CI 0.12-0.84, p=0.021 for DSS. Unfavorable prognosis might stem from the non-canonical role of FI, as the staining pattern did not correlate with C4d - the product of FI-supported degradation of active complement component C4b. To elucidate that, we engineered three human NSCLC cell lines naturally expressing FI with CRISPR/Cas9 technology, and compared the transcriptome of FI-deficient and FI-sufficient clones in each cell line. RNA sequencing revealed differentially expressed genes engaged in intracellular signaling pathways controlling proliferation, apoptosis, and responsiveness to growth factors. Moreover, in vitro colony-formation assays showed that FI-deficient cells formed smaller foci than FI-sufficient NSCLC cells, but their size increased when purified FI protein was added to the medium. We postulate that a non-canonical activity of FI influences cellular physiology and contributes to the poor prognosis of lung cancer patients.
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| 6. |
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| 7. |
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| 8. |
- Gunnarsdóttir, Frida Björk, et al.
(författare)
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Inflammatory macrophage derived TNFα downregulates estrogen receptor α via FOXO3a inactivation in human breast cancer cells
- 2020
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827. ; 390:1
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Tidskriftsartikel (refereegranskat)abstract
- Patients with estrogen receptor α positive (ERα+) breast cancer can respond to endocrine therapy, but treatment resistance is common and associated with downregulation of ERα expression in the dormant residual cells. Here we show, using long-term NSG xenograft models of human breast cancer and primary human monocytes, in vitro primary cell cultures and tumors from breast cancer patients, that macrophage derived tumor necrosis factor alpha (TNFα) downregulates ERα in breast cancer cells via inactivation of the transcription factor Forkhead box O transcription factor 3a (FOXO3a). Moreover, presence of tumor associated macrophages in the primary tumor of breast cancer patients, was associated with ERα negativity, and with worse prognosis in patients with ERα+ tumors. We propose that pro-inflammatory macrophages, despite being tumoricidal, may have direct effects on tumor progression and endocrine resistance in breast cancer patients. Our findings suggest that TNFα antagonists should be evaluated for treatment of ERα+ breast cancer.
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| 9. |
- Karakaya, Sinan, et al.
(författare)
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Cytoplasmic HIF-2α as tissue biomarker to identify metastatic sympathetic paraganglioma
- 2023
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Ingår i: Scientific Reports. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors. PGLs can further be divided into sympathetic (sPGLs) and head-and-neck (HN-PGLs). There are virtually no treatment options, and no cure, for metastatic PCCs and PGLs (PPGLs). Here, we composed a tissue microarray (TMA) consisting of 149 PPGLs, reflecting clinical features, presenting as a useful resource. Mutations in the pseudohypoxic marker HIF-2 & alpha; correlate to an aggressive tumor phenotype. We show that HIF-2 & alpha; localized to the cytoplasm in PPGLs. This subcompartmentalized protein expression differed between tumor subtypes, and strongly correlated to proliferation. Half of all sPGLs were metastatic at time of diagnosis. Cytoplasmic HIF-2 & alpha; was strongly expressed in metastatic sPGLs and predicted poor outcome in this subgroup. We propose that higher cytoplasmic HIF-2 & alpha; expression could serve as a useful clinical marker to differentiate paragangliomas from pheochromocytomas, and may help predict outcome in sPGL patients.
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| 10. |
- Kremlitzka, Mariann, et al.
(författare)
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Alternative translation and retrotranslocation of cytosolic C3 that detects cytoinvasive bacteria
- 2022
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Ingår i: Cellular and Molecular Life Sciences. - : Springer Science and Business Media LLC. - 1420-682X .- 1420-9071. ; 79:6
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Tidskriftsartikel (refereegranskat)abstract
- Complement C3 was originally regarded as a serum effector protein, although recent data has emerged suggesting that intracellular C3 can also regulate basic cellular processes. Despite the growing interest in intracellular C3 functions, the mechanism behind its generation has not been demonstrated. In this study we show that C3 can be expressed from an alternative translational start site, resulting in C3 lacking the signal peptide, which is therefore translated in the cytosol. In contrast to the secreted form, alternatively translated cytosolic C3 is not glycosylated, is present mainly in a reduced state, and is turned over by the ubiquitin–proteasome system. C3 can also be retrotranslocated from the endoplasmic reticulum into the cytosol, structurally resembling secreted C3. Finally, we demonstrate that intracellular cytosolic C3 can opsonize invasive Staphylococcus aureus within epithelial cell, slowing vacuolar escape as well as impacting bacterial survival on subsequent exposure to phagocytes. Our work therefore reveals the existence and origin of intracellular, cytosolic C3, and demonstrates functions for cytosolic C3 in intracellular detection of cytoinvasive pathogens.
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| 11. |
- Kremlitzka, Mariann, et al.
(författare)
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Interaction of Serum-Derived and Internalized C3 With DNA in Human B Cells-A Potential Involvement in Regulation of Gene Transcription
- 2019
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Beside its classical role as a serum effector system of innate immunity, evidence is accumulating that complement has an intracellular repertoire of components that provides not only immune defense, but also functions to maintain cellular homeostasis. While complement proteins, mainly the central component C3, have been detected in B cells, their exact function and source remain largely unexplored. In this study, we investigated the expression and origin of intracellular C3 in human B cells together with its role in B cell homeostasis. Our data provide evidence that endogenous expression of C3 is very low in human B cells and, in accordance with the recent publication, the main origin of intracellular C3 is the serum. Interestingly, we found that both serum-derived and purified C3 are able to enter the nucleus of viable B cells, suggesting its potential involvement in regulation of gene transcription. ELISA, gel shift assay, confocal microscopy, and chromatin immunoprecipitation proved that C3 and C3a strongly bind to nuclear DNA, and among the interacting genes there are key factors of lymphocyte development and differentiation. The strong interaction of C3 with histone proteins and its potential ability to induce chromatin rearrangement suggest that C3/C3a might regulate DNA transcription via chromatin remodeling. Our data reveal a novel, hitherto undescribed role of C3 in immune cell homeostasis, which further extends the repertoire how complement links innate and adaptive immunity and regulates basic processes of the cells.
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| 12. |
- Li, Shuxian, et al.
(författare)
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Recruitment of C4b-binding protein is not a complement evasion strategy employed by Staphylococcus aureus
- 2023
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Ingår i: Microbiology (United Kingdom). - 1350-0872. ; 169:9
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Tidskriftsartikel (refereegranskat)abstract
- Complement offers a first line of defence against infection through the opsonization of microbial pathogens, recruitment of professional phagocytes to the infection site and the coordination of inflammatory responses required for the resolution of infection. Staphylococcus aureus is a successful pathogen that has developed multiple mechanisms to thwart host immune responses. Understanding the precise strategies employed by S. aureus to bypass host immunity will be paramount for the development of vaccines and or immunotherapies designed to prevent or limit infection. To gain a better insight into the specific immune evasion mechanisms used by S. aureus we examined the pathogen’s interaction with the soluble complement inhibitor, C4b-binding protein (C4BP). Previous studies indicated that S. aureus recruits C4BP using a specific cell-wall-anchored surface protein and that bound C4BP limits complement deposition on the staphylococcal surface. Using flow-cytometric-based bacterial-protein binding assays we observed no interaction between S. aureus and C4BP. Moreover, we offer a precautionary warning that C4BP isolated from plasma can be co-purified with minute quantities of human IgG, which can distort binding analysis between S. aureus and human-derived proteins. Combined our data indicates that recruitment of C4BP is not a complement evasion strategy employed by S. aureus.
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| 13. |
- Mihlan, Michael, et al.
(författare)
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Monomeric C-reactive protein modulates classic complement activation on necrotic cells
- 2011
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Ingår i: FASEB Journal. - : Wiley. - 1530-6860 .- 0892-6638. ; 25:12, s. 4198-4210
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Tidskriftsartikel (refereegranskat)abstract
- The acute-phase protein C-reactive protein (CRP) recruits C1q to the surface of damaged cells and thereby initiates complement activation. However, CRP also recruits complement inhibitors, such as C4b-binding protein (C4bp) and factor H, which both block complement progression at the level of C3 and inhibits inflammation. To define how CRP modulates the classic complement pathway, we studied the interaction of CRP with the classic pathway inhibitor C4bp. Monomeric CRP (mCRP), but not pentameric CRP (pCRP), binds C4bp and enhances degradation of C4b and C3b. Both C1q, the initiator, and C4bp, the inhibitor of the classic pathway, compete for mCRP binding, and this competition adjusts the local balance of activation and inhibition. After attachment of pCRP to the surface of necrotic rat myocytes, generation of mCRP was demonstrated over a period of 18 h. Similarly, a biological role for mCRP, C1q, and C4bp in the disease setting of acute myocardial infarction was revealed. In this inflamed tissue, mCRP, pCRP, C4bp, C1q, and C4d were detected in acetone-fixed and in unfixed tissue. Protein levels were enhanced 6 h to 5 d after infarction. Thus, mCRP bound to damaged cardiomyocytes recruits C1q to activate and also C4bp to control the classic complement pathway.-Mihlan, M., Blom, A. M., Kupreishvili, K., Lauer, N., Stelzner, K., Bergstro " m, F., Niessen, H. W. M., Zipfel, P. F. Monomeric C-reactive protein modulates classic complement activation on necrotic cells. FASEB J. 25, 4198-4210 (2011). www.fasebj.org
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| 14. |
- Mika, Angela, et al.
(författare)
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Novel Scabies Mite Serpins Inhibit the Three Pathways of the Human Complement System
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7
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Tidskriftsartikel (refereegranskat)abstract
- Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes significant morbidity worldwide, in particular within socially disadvantaged populations. In order to identify mechanisms that enable the scabies mite to evade human immune defenses, we have studied molecules associated with proteolytic systems in the mite, including two novel scabies mite serine protease inhibitors (SMSs) of the serpin superfamily. Immunohistochemical studies revealed that within mite-infected human skin SMSB4 (54 kDa) and SMSB3 (47 kDa) were both localized in the mite gut and feces. Recombinant purified SMSB3 and SMSB4 did not inhibit mite serine and cysteine proteases, but did inhibit mammalian serine proteases, such as chymotrypsin, albeit inefficiently. Detailed functional analysis revealed that both serpins interfered with all three pathways of the human complement system at different stages of their activation. SMSB4 inhibited mostly the initial and progressing steps of the cascades, while SMSB3 showed the strongest effects at the C9 level in the terminal pathway. Additive effects of both serpins were shown at the C9 level in the lectin pathway. Both SMSs were able to interfere with complement factors without protease function. A range of binding assays showed direct binding between SMSB4 and seven complement proteins (C1, properdin, MBL, C4, C3, C6 and C8), while significant binding of SMSB3 occurred exclusively to complement factors without protease function (C4, C3, C8). Direct binding was observed between SMSB4 and the complement proteases C1s and C1r. However no complex formation was observed between either mite serpin and the complement serine proteases C1r, C1s, MASP-1, MASP-2 and MASP-3. No catalytic inhibition by either serpin was observed for any of these enzymes. In summary, the SMSs were acting at several levels mediating overall inhibition of the complement system and thus we propose that they may protect scabies mites from complement-mediated gut damage.
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| 15. |
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| 16. |
- Mohlin, Frida, et al.
(författare)
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Analysis of genes coding for CD46, CD55 and C4b-binding protein in patients with idiopathic, recurrent, spontaneous pregnancy loss.
- 2013
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Ingår i: European Journal of Immunology. - : Wiley. - 1521-4141 .- 0014-2980. ; 43:6, s. 1617-1629
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Tidskriftsartikel (refereegranskat)abstract
- Since a tightly regulated complement system is needed for a successful pregnancy, we hypothesized that alterations in complement inhibitors may be associated with idiopathic, recurrent miscarriage. We sequenced all exons coding for three complement inhibitors: C4b-binding protein (C4BP), CD46 and CD55 in 384 childless women with at least two miscarriages that could not be explained by known risk factors. Several alterations were found in C4BPA, of which the R120H, I126T, and the G423T mutations affected the expression level and/or the ability of recombinant C4BP to serve as cofactor for factor I. The only variant in C4BPB was located in the C-terminal part, and did not impair the polymerization of the molecule. Our results identify for the first time alterations in C4BP in women experiencing recurrent miscarriages. We also found four CD46 alterations in individual patients that were not found in healthy controls. One of the rare variants, P324L, showed decreased expression, whereas N213I resulted in deficient protein processing as well as an impaired cofactor activity in the degradation of both C4b and C3b. The identified alterations may result in in vivo consequences and contribute to the disorder but the degree of association must be evaluated in larger cohorts.
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| 17. |
- Mohlin, Frida C., et al.
(författare)
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Analysis of C3 gene variants in patients with idiopathic recurrent spontaneous pregnancy loss
- 2018
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9:AUG
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Tidskriftsartikel (refereegranskat)abstract
- Miscarriage is the most common complication of pregnancy. Approximately 1% of couples trying to conceive will experience recurrent miscarriages, defined as three or more consecutive pregnancy losses and many of these cases remain idiopathic. Complement is implicated both in the physiology and pathology of pregnancy. Therefore, we hypothesized that alterations in the C3 gene could potentially predispose to this disorder. We performed full Sanger sequencing of all exons of C3, in 192 childless women, with at least two miscarriages and without any known risk factors. All exons carrying non-synonymous alterations found in the patients were then sequenced in a control group of 192 women. None of the identified alterations were significantly associated with the disorder. Thirteen identified non-synonymous alterations (R102G, K155Q, L302P, P314L, Y325H, V326A, S327P, V330I, K633R, R735W, R1591G, G1606D, and S1619R) were expressed recombinantly, upon which C3 expression and secretion were determined. The L302P and S327P were not secreted from the cells, likely due to misfolding and intracellular degradation. Y325H, V326A, V3301I, R1591G, and G1606D yielded approximately half C3 concentration in the cell media compared with wild type (WT). We analyzed the hemolytic activity of the secreted C3 variants by reconstituting C3-depleted serum. In this assay, R1591G had impaired hemolytic activity while majority of remaining mutants instead had increased activity. R1591G also yielded more factor B activation in solution compared with WT. R1591G and G1606D showed impaired degradation by factor I, irrespectively if factor H, CD46, or C4b-binding protein were used as cofactors. These two C3 mutants showed impaired binding of the cofactors and/or factor I. Taken together, several alterations in C3 were identified and some of these affected the secretion and/or the function of the protein, which might contribute to the disorder but the degree of association must be evaluated in larger cohorts.
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| 18. |
- Mohlin, Frida, et al.
(författare)
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Functional characterization of two novel non-synonymous alterations in CD46 and a Q950H change in factor H found in atypical hemolytic uremic syndrome patients.
- 2015
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Ingår i: Molecular Immunology. - : Elsevier BV. - 1872-9142 .- 0161-5890. ; 65:2, s. 367-376
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Tidskriftsartikel (refereegranskat)abstract
- Atypical hemolytic uremic syndrome (aHUS) is a disease of complement dysregulation, characterized by hemolytic anemia, thrombocytopenia and acute renal failure. Mutations in complement inhibitors are major risk factors for development of aHUS. The three aHUS patients reported in this study had several previously identified alterations in complement inhibitors; e.g. risk haplotypes in CD46 and factor H but we also identified two novel heterozygous non-synonymous CD46 alterations (p.E142Q and p.G259V). Presence of G259V caused decreased expression of the recombinant mutant CD46 compared to wild type (WT). Western blot analysis showed that the majority of the expressed G259V protein was in the precursor form, suggesting that it is processed less efficiently than WT. Low CD46 expression on the surface of the patient's neutrophils confirmed the in vitro results. Further, G259V had a substantially impaired ability to act as a cofactor to factor I, in the degradation of both C3b and C4b. The E142Q mutant showed neither decreased expression nor impaired function. Two of the patients also had a heterozygous non-synonymous alteration in factor H (p.Q950H), reported previously in aHUS but not functionally tested. This variant showed moderately impaired function in hemolytic assays, both using patient sera and recombinant proteins. The recombinant Q950H also showed a somewhat decreased expression compared to WT but the complement inhibitory function in fluid phase was normal. Taken together, we report a novel CD46 alteration showing both a decreased protein expression and substantially impaired cofactor function (G259V) and another without an effect on expression or cofactor function (E142Q). Moreover, mild consequences of a previously reported aHUS associated rare variant in factor H (Q950H) was also revealed, underlining the clear need for functional characterization of each new aHUS associated mutation.
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| 19. |
- Mohlin, Frida, et al.
(författare)
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Purification and Functional Characterization of C4b-Binding Protein (C4BP).
- 2014
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Ingår i: Methods in Molecular Biology. - Totowa, NJ : Humana Press. - 1940-6029. ; 1100, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- C4b-binding protein (C4BP) is a soluble, 570 kDa large glycoprotein, present in plasma at a concentration of approximately 200 mg/L. C4BP is the main inhibitor of the classical and lectin pathways of complement, where it controls C4b-mediated reactions. Here, we describe a method for purification of C4BP from human plasma, which is based on barium chloride precipitation, anion exchange chromatography, and gel filtration. We also describe a functional assay, in which C4BP's cofactor activity to factor I, in the degradation of C4b, can be assessed.
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| 20. |
- Mohlin, Frida, et al.
(författare)
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Scabies mite inactivated serine protease paralogs inhibit the human complement system.
- 2009
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:12, s. 7809-7817
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Tidskriftsartikel (refereegranskat)abstract
- Infestation of skin by the parasitic itch mite Sarcoptes scabiei afflicts 300 million people worldwide and there is a need for novel and efficient therapies. We have previously identified a multigene family of serine proteases comprising multiple catalytically inactive members (scabies mite-inactivated protease paralogs (SMIPPs)), which are secreted into the gut of S. scabiei. SMIPPs are located in the mite gut and in feces excreted into the upper epidermis. Scabies mites feed on epidermal protein, including host plasma; consequently, they are exposed to host defense mechanisms both internally and externally. We found that two recombinantly expressed SMIPPs inhibited all three pathways of the human complement system. Both SMIPPs exerted their inhibitory action due to binding of three molecules involved in the three different mechanisms which initiate complement: C1q, mannose-binding lectin, and properdin. Both SMIPPs bound to the stalk domains of C1q, possibly displacing or inhibiting C1r/C1s, which are associated with the same domain. Furthermore, we found that binding of both SMIPPs to properdin resulted in prevention of assembly of the alternative pathway convertases. However, the SMIPPs were not able to dissociate already formed convertases. Immunohistochemical staining demonstrated the presence of C1q in the gut of scabies mites in skin burrows. We propose that SMIPPs minimize complement-mediated gut damage and thus create a favorable environment for the scabies mites.
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| 21. |
- Pang, Siew Siew, et al.
(författare)
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The structural basis for complement inhibition by gigastasin, a protease inhibitor from the giant Amazon leech
- 2017
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 199:11, s. 3883-3891
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Tidskriftsartikel (refereegranskat)abstract
- Complement is crucial to the immune response, but dysregulation of the system causes inflammatory disease. Complement is activated by three pathways: classical, lectin, and alternative. The classical and lectin pathways are initiated by the C1r/C1s (classical) and MASP-1/MASP-2 (lectin) proteases. Given the role of complement in disease, there is a requirement for inhibitors to control the initiating proteases. In this article, we show that a novel inhibitor, gigastasin, from the giant Amazon leech, potently inhibits C1s and MASP-2, whereas it is also a good inhibitor of MASP-1. Gigastasin is a poor inhibitor of C1r. The inhibitor blocks the active sites of C1s and MASP-2, as well as the anion-binding exosites of the enzymes via sulfotyrosine residues. Complement deposition assays revealed that gigastasin is an effective inhibitor of complement activation in vivo, especially for activation via the lectin pathway. These data suggest that the cumulative effects of inhibiting both MASP-2 and MASP-1 have a greater effect on the lectin pathway than the more potent inhibition of only C1s of the classical pathway.
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| 22. |
- Samuelsson, Marcus, 1967-, et al.
(författare)
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Ett observationsprotokoll för att studera ledarskap för lärande
- 2021
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Ingår i: Venue. - Linköping : Linköping University Electronic Press. - 2001-788X. ; :19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Ett sätt att få syn på hur lärare leder undervisning är att använda sig av observationer och då kan ett observationsprotokoll vara till hjälp. Hur ett protokoll togs fram och hur det till slut ser ut beskrivs i denna artikel.
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| 23. |
- Samuelsson, Marcus, 1967-, et al.
(författare)
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Ett observationsprotokoll för att studera ledarskap för lärande
- 2022
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Ingår i: Ledarskap för lärande. - Linköping : Linköping University Electronic Press. - 9789179292881 ; , s. 27-35
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Denna artikel beskriver en process och en produkt som tagits fram inom ramen för ett ULF-projekt (Thorsten, 2021), ett forskningsprojekt kallat Ledarskap för lärande. Namnet och inriktningen speglar ett intresse från skolledare och lärare i tre kommuner, Mjölby, Norrköping och Söderkö- ping. I dessa kommuner fanns ett behov av att öka kunskapen om ledarskap i relation till lärande vilket gjorde att ett praktiknära forskningsprojekt tillsammans med två forskare från Linköpings universitet påbörjades. Från varje kommun rekryterades medforskande lärare (två från Mjölby, fyra från Norrköping och två från Söderköping) som skulle delta i forskningsgruppen.I forskningsprojektets inledning bestämdes att vi, som ett sätt att påverka lärares sätt att leda under- visning, skulle utforma en intervention i form av en fortbildning för lärare. Till följd av det be- stämdes också att interventionen skulle föregås och följas upp av observationer av lärarna som skulle delta i interventionen. Dessa observationer skulle genomföras av de medforskande lärarna. Till stöd för deras observationer behövdes ett observationsprotokoll. Syftet med protokollet var att identifiera kvalitativa skillnader i lärares sätt att leda undervisning.Vi påbörjade arbetet med att diskutera kring vad observationer innebär och utgick då från en text av Granström (2004) som handlar om att göra tillförlitliga observationer och om vilken roll obser- vatören kan inta i relation till dem/de som observeras. Vi började också resonera om tänkbara svar på två grundläggande frågor om observation som Arno Bellack (1978) formulerat Vilka dimens- ioner av klassrumsbeteenden ska observeras? och Hur ska observationerna utföras? Dessa frågor kom att följa oss under hela processen och svaret på dem fann vi på flera sätt. Hur observations- protokollet kom att se ut påverkades av flera faktorer: (a) den erfarenhetsbaserade kunskapen i forskargruppen, (b) andra observationsprotokoll, (c) tidigare forskning och (d) utprovning av protokollet. Dessa fyra delar sammanvävdes på olika sätt under olika delar av processen.
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| 24. |
- Smailhodzic, Dzenita, et al.
(författare)
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Zinc supplementation inhibits complement activation in age-related macular degeneration.
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Age-related macular degeneration (AMD) is the leading cause of blindness in the Western world. AMD is a multifactorial disorder but complement-mediated inflammation at the level of the retina plays a pivotal role. Oral zinc supplementation can reduce the progression of AMD but the precise mechanism of this protective effect is as yet unclear. We investigated whether zinc supplementation directly affects the degree of complement activation in AMD and whether there is a relation between serum complement catabolism during zinc administration and the complement factor H (CFH) gene or the Age-Related Maculopathy susceptibility 2 (ARMS2) genotype. In this open-label clinical study, 72 randomly selected AMD patients in various stages of AMD received a daily supplement of 50 mg zinc sulphate and 1 mg cupric sulphate for three months. Serum complement catabolism-defined as the C3d/C3 ratio-was measured at baseline, throughout the three months of supplementation and after discontinuation of zinc administration. Additionally, downstream inhibition of complement catabolism was evaluated by measurement of anaphylatoxin C5a. Furthermore, we investigated the effect of zinc on complement activation in vitro. AMD patients with high levels of complement catabolism at baseline exhibited a steeper decline in serum complement activation (p<0.001) during the three month zinc supplementation period compared to patients with low complement levels. There was no significant association of change in complement catabolism and CFH and ARMS2 genotype. In vitro zinc sulphate directly inhibits complement catabolism in hemolytic assays and membrane attack complex (MAC) deposition on RPE cells. This study provides evidence that daily administration of 50 mg zinc sulphate can inhibit complement catabolism in AMD patients with increased complement activation. This could explain part of the mechanism by which zinc slows AMD progression.
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| 25. |
- Thoren, Lina A., et al.
(författare)
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UPF2 Is a Critical Regulator of Liver Development, Function and Regeneration
- 2010
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Nonsense-mediated mRNA decay (NMD) is a post-transcriptional RNA surveillance process that facilitates the recognition and destruction of mRNAs bearing premature terminations codons (PTCs). Such PTC-containing (PTC+) mRNAs may arise from different processes, including erroneous processing and expression of pseudogenes, but also from more regulated events such as alternative splicing coupled NMD (AS-NMD). Thus, the NMD pathway serves both as a silencer of genomic noise and a regulator of gene expression. Given the early embryonic lethality in NMD deficient mice, uncovering the full regulatory potential of the NMD pathway in mammals will require the functional assessment of NMD in different tissues. Methodology/Principal Findings: Here we use mouse genetics to address the role of UPF2, a core NMD component, in the development, function and regeneration of the liver. We find that loss of NMD during fetal liver development is incompatible with postnatal life due to failure of terminal differentiation. Moreover, deletion of Upf2 in the adult liver results in hepatosteatosis and disruption of liver homeostasis. Finally, NMD was found to be absolutely required for liver regeneration. Conclusion/Significance: Collectively, our data demonstrate the critical role of the NMD pathway in liver development, function and regeneration and highlights the importance of NMD for mammalian biology.
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| 26. |
- Thorsten, Anja, 1974-, et al.
(författare)
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Ledarskap för lärande – en inramning
- 2022
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Ingår i: Ledarskap för lärande. - Linköping : Linköping University Electronic Press. - 9789179292881 ; , s. 7-9
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 27. |
- Thorsten, Anja, 1974-, et al.
(författare)
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Modell 1-projektets faser
- 2022
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Ingår i: Ledarskap för lärande. - Linköping : Linköping University Electronic Press. - 9789179292881 ; , s. 24-26
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Detta projekt har varit det som benämns som ett modell 1-projekt inom ramen för regionens arbete med ULF (utveckling, lärande och forskning). Modell 1 är ett praktiknära forskningsprojekt som sker i samverkan mellan Linköpings universitet och kommunerna i regionen. Det är tvååriga projekt som initieras av regionens skolchefsnätverk (Thorsten, 2021). Tanken är att modell 1-projekt ska resultera i forskning som ba-seras på de behov som identifieras i regionen och att även om alla?kommuner inte deltar aktivt i processen ska resultaten komma hela regionen till del. I detta kapitel beskrivs projektets övergripande process. Mer detaljerade beskrivningar av de metoder som har använts ges i respektive resultatkapitel.?
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| 28. |
- Thorsten, Anja, 1974-, et al.
(författare)
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Till nytta för vem och på vilket sätt?
- 2022
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Ingår i: Ledarskap för lärande. - Linköping : Linköping University Electronic Press. - 9789179292881 ; , s. 111-113
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I detta sista kapitel diskuterar vi den tänkbara nyttan av det vi kommit fram till i ULF-projektet?Ledarskap för lärande. Att vi kommit fram till att lärares sätt att leda undervisning kan påverkas,?utvecklas och förändras med stöd av ett kompetensutvecklingsprogram visas i resultatet. Där framkommer också likheter, skillnader och kvaliteter utifrån olika skattningar av ledarskap för lärande. Vidare visas att kompetensutvecklingen givit lärarna begrepp, modeller och teorier som tillskott i deras yrkesspråkliga verktygslåda. Så med detta sagt, åter till frågan om hur resultat som de ovan?nämnda kan bli användbara för olika läsare och målgrupper. Användbara i betydelsen att lära eller påminna om hur lärare på ett bättre sätt ska kunna leda undervisning (Samuelsson, Kilman, Lindqvist, Prytz, Sveider, Thorsten, Wedin, Karlberg, Andersson, Johansson & Tväråna, 2020) och bedriva ledarskap för lärande, så att alla elever får bättre förutsättningar för att lära sig. Vi resonerar fortsatt om fyra olika målgrupper (a) lärare, (b) skolledare, (c) forskare och (d) en undervisningsintresserad allmänhet.
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| 29. |
- van de Ven, Johannes P. H., et al.
(författare)
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A functional variant in the CFI gene confers a high risk of age-related macular degeneration
- 2013
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:7, s. 813-813
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Tidskriftsartikel (refereegranskat)abstract
- Up to half of the heritability of age-related macular degeneration (AMD) is explained by common variants(1-5). Here, we report the identification of a rare, highly penetrant missense mutation in CFI encoding a p.Gly119Arg substitution that confers high risk of AMD (P = 3.79 x 10(-6); odds ratio (OR) = 22.20, 95% confidence interval (CI) = 2.98-164.49). Plasma and sera from cases carrying the p.Gly119Arg substitution mediated the degradation of C3b, both in the fluid phase and on the cell surface, to a lesser extent than those from controls. Recombinant protein studies showed that the Gly119Arg mutant protein is both expressed and secreted at lower levels than wild-type protein. Consistent with these findings, human CFI mRNA encoding Arg119 had reduced activity compared to wild-type mRNA encoding Gly119 in regulating vessel thickness and branching in the zebrafish retina. Taken together, these findings demonstrate that rare, highly penetrant mutations contribute to the genetic burden of AMD.
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| 30. |
- Werner, Lacie M., et al.
(författare)
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Neisseria gonorrhoeae co-opts C4b-binding protein to enhance complement-independent survival from neutrophils
- 2023
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 19:3
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Tidskriftsartikel (refereegranskat)abstract
- Neisseria gonorrhoeae (Gc) is a human-specific pathogen that causes the sexually transmitted infection gonorrhea. Gc survives in neutrophil-rich gonorrheal secretions, and recovered bacteria predominantly express phase-variable, surface-expressed opacity-associated (Opa) proteins (Opa+). However, expression of Opa proteins like OpaD decreases Gc survival when exposed to human neutrophils ex vivo. Here, we made the unexpected observation that incubation with normal human serum, which is found in inflamed mucosal secretions, enhances survival of Opa+ Gc from primary human neutrophils. We directly linked this phenomenon to a novel complement-independent function for C4b-binding protein (C4BP). When bound to the bacteria, C4BP was necessary and sufficient to suppress Gc-induced neutrophil reactive oxygen species production and prevent neutrophil phagocytosis of Opa+ Gc. This research identifies for the first time a complement-independent role for C4BP in enhancing the survival of a pathogenic bacterium from phagocytes, thereby revealing how Gc exploits inflammatory conditions to persist at human mucosal surfaces.
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