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3 Publications visible to you, out of a total of 3
Immune modulation by complement receptor 3-dependent human monocyte TGF-beta1-transporting vesicles.

Abstract (Expand)

Extracellular vesicles have an important function in cellular communication. Here, we show that human and mouse monocytes release TGF-beta1-transporting vesicles in response to the pathogenic fungus … Candida albicans. Soluble beta-glucan from C. albicans binds to complement receptor 3 (CR3, also known as CD11b/CD18) on monocytes and induces the release of TGF-beta1-transporting vesicles. CR3-dependence is demonstrated using CR3-deficient (CD11b knockout) monocytes generated by CRISPR-CAS9 genome editing and isolated from CR3-deficient (CD11b knockout) mice. These vesicles reduce the pro-inflammatory response in human M1-macrophages as well as in whole blood. Binding of the vesicle-transported TGF-beta1 to the TGF-beta receptor inhibits IL1B transcription via the SMAD7 pathway in whole blood and induces TGFB1 transcription in endothelial cells, which is resolved upon TGF-beta1 inhibition. Notably, human complement-opsonized apoptotic bodies induce production of similar TGF-beta1-transporting vesicles in monocytes, suggesting that the early immune response might be suppressed through this CR3-dependent anti-inflammatory vesicle pathway.

Authors: L. D. Halder, E. A. H. Jo, M. Z. Hasan, M. Ferreira-Gomes, T. Kruger, M. Westermann, D. I. Palme, G. Rambach, N. Beyersdorf, C. Speth, I. D. Jacobsen, O. Kniemeyer, B. Jungnickel, P. F. Zipfel, C. Skerka

Date Published: 11th May 2020

Publication Type: Not specified

Regulation of the Germinal Center Reaction and Somatic Hypermutation Dynamics by Homologous Recombination.

Abstract (Expand)

During somatic hypermutation (SHM) of Ig genes in germinal center B cells, lesions introduced by activation-induced cytidine deaminase are processed by multiple error-prone repair pathways. Although … error-free repair by homologous recombination (HR) is crucial to prevent excessive DNA strand breakage at activation-induced cytidine deaminase off-target genes, its role at the hypermutating Ig locus in the germinal center is unexplored. Using B cell-specific inactivation of the critical HR factor Brca2, we detected decreased proliferation, survival, and thereby class switching of ex vivo-activated B cells. Intriguingly, an HR defect allowed for a germinal center reaction and affinity maturation in vivo, albeit at reduced amounts. Analysis of SHM revealed that a certain fraction of DNA lesions at C:G bp was indeed repaired in an error-free manner via Brca2 instead of being processed by error-prone translesion polymerases. By applying a novel pseudo-time in silico analysis of mutational processes, we found that the activity of A:T mutagenesis during SHM increased during a germinal center reaction, but this was in part defective in Brca2-deficient mice. These mutation pattern changes in Brca2-deficient B cells were mostly specific for the Ig V region, suggesting a local or time-dependent need for recombination repair to survive high rates of SHM and especially A:T mutagenesis.

Authors: G. Hirth, C. M. Svensson, K. Bottcher, S. Ullrich, M. T. Figge, B. Jungnickel

Date Published: 15th Sep 2019

Publication Type: Not specified

Serum FHR1 binding to necrotic-type cells activates monocytic inflammasome and marks necrotic sites in vasculopathies.

Abstract (Expand)

Persistent inflammation is a hallmark of many human diseases, including anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) and atherosclerosis. Here, we describe a dominant trigger of … inflammation: human serum factor H-related protein FHR1. In vitro, this protein selectively binds to necrotic cells via its N-terminus; in addition, it binds near necrotic glomerular sites of AAV patients and necrotic areas in atherosclerotic plaques. FHR1, but not factor H, FHR2 or FHR3 strongly induces inflammasome NLRP3 in blood-derived human monocytes, which subsequently secrete IL-1beta, TNFalpha, IL-18 and IL-6. FHR1 triggers the phospholipase C-pathway via the G-protein coupled receptor EMR2 independent of complement. Moreover, FHR1 concentrations of AAV patients negatively correlate with glomerular filtration rates and associate with the levels of inflammation and progressive disease. These data highlight an unexpected role for FHR1 during sterile inflammation, may explain why FHR1-deficiency protects against certain diseases, and identifies potential targets for treatment of auto-inflammatory diseases.

Authors: S. Irmscher, S. R. Brix, S. L. H. Zipfel, L. D. Halder, S. Mutluturk, S. Wulf, E. Girdauskas, H. Reichenspurner, R. A. K. Stahl, B. Jungnickel, T. Wiech, P. F. Zipfel, C. Skerka

Date Published: 4th Jul 2019

Publication Type: Not specified

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