Association of IL-10 and IL-33 Cytokine Gene Variants with Atherosclerosis Risk in a Jordanian Population
A. Ali Deeb1, K. Amawi1, A. Hamedallah1, T. Al Ramadneh1
1Zarqa University, Allied Medical Science, Zarqa, Jordan
The current study aims to investigate the relation IL-10 and IL-33 cytokine gene variants to atherosclerosis risk in a Jordanian population. Previous studies have shown that cytokines can affect the progression of the disease in individuals with genetic variations. This study analysis revealed a possible protective effect toward coronary artery disease (CAD), implications in the prevalence of the T allele and T/T genotype at the IL-33 rs7044343 position noticed in the control group compared to patients. Although the IL-33 genotype frequencies were the same between patients and controls, the deviation from–Hardy-Weinberg equilibrium indicated possible population stratification. Moreover, atherosclerosis patients had the IL-33 serum levels significantly lower, consistent with its proposed protective role. The IL-10, the −1082 A > G (rs1800896) polymorphism showed a high significance in the distribution of the genotype, suggesting its potential role in the progression of atherosclerosis. These results highlight the significance of genetic diversity and the complex correlation between cytokine polymorphisms and atherosclerosis. Future studies should examine the functional importance of genetic variations and their relations with the condition element to create further targeted prevention and treatment procedures for atherosclerosis patients.
Regulation of the function and phenotype of neutrophils by interferon regulatory factor 8
A. J. C. Grimm1, L. Polmann1, J. Roth1, K. Barczyk-Kahlert1
1University Münster, Institute of Immunology, Münster, Germany
Sepsis is a poorly understood condition with a high mortality rate. Neutrophils are the most prevalent type of circulating leukocytes performing effector functions to eliminate threads causing systemic infections. The NF-kB and mitogen-activated protein kinase (MAPK) pathways regulate neutrophil responses to proinflammatory mediators like LPS. The transcription factor interferon-regulatory-factor-8 (IRF8) plays a pivotal role during differentiation of myeloid cells, directing development into monocytes while inhibiting neutrophil differentiation to ensure homeostasis. Mice lacking IRF8 display enhanced neutrophil amounts and survive longer during endotoxic-shock. Our aim is therefore to investigate the IRF8 mediated impact on neutrophil phenotype and function during systemic infections. Neutrophil functions with a focus on cytokine secretion, ROS production and phagocytosis in steady state and in response to LPS were examined via ELISA, RT-qPCR and flow cytometry and potentially altered pathways were analyzed via Western Blot. HoxB8 and primary IRF8ko neutrophils exhibited significantly lower cytokine levels as well as transcription of TNF-α, IL-1β, IL-6 and IL-12a compared to WT counterparts upon LPS treatment. HoxB8 and primary neutrophils in WT further exhibited significantly higher ROS levels and phagocytic capacity than IRF8ko equivalents leading to the hypothesis of a hyporesponsive state in IRF8ko neutrophils. Analysis of NF-kB and MAPK pathway components revealed a defective activation of p38 and ERK1/2 and revealed lower p65 phosphorylation in HoxB8 and primary IRF8ko-neutrophils upon LPS stimulation compared to WT counterparts (Figure 1). This indicates significant alterations in the activation and signaling transduction of MAPK and NF-kB signaling pathways upon LPS stimulation. Identification of molecular events is required to elucidate the role of IRF8 in the function and phenotype of neutrophils and may be beneficial for developing novel sepsis therapies.
Figure 1.
Integrin β1 Coordinates Mast Cell Perivascular Positioning and Vasoactive Functions to License Leukocyte Extravasation
A. Hoffmann1, K. Katsoulis-Dimitriou1, J. Dudeck1, M. Voss1, A. Dudeck1
1Otto-von-Guericke-Universität Magdeburg, Institute of Molecular and Clinical Immunology, Magdeburg, Germany
Purpose: Mast cells (MCs) play a pivotal role as innate sentinels by their immediate release of pro-inflammatory mediators, including TNF and histamine. Notably, perivascular MCs critically impact on the onset and kinetics of inflammation by their directional release of mediators into the bloodstream. However, the mechanisms underlying MC attachment to the vessel wall, as a prerequisite for the intraluminal degranulation, remain to be fully elucidated.
Method(s): Using a conditional knockout in MCs, we studied the relevance of the adhesion molecule integrin β1 (Itgb1) for perivascular MC vessel attachment and degranulation in vitro and in vivo. In the contact hypersensitivity (CHS) mouse model, ear swelling and cell infiltration was analyzed. MC degranulation was evaluated via live cell imaging in vitro and in CHS in vivo.
Results: Fluorescence microscopy of murine Itgb1-deficient MCs (MCΔItgb1) revealed that Itgb1 is critical for the spindle-like morphology, homogeneous tissue distribution, and perivascular alignment of MCs in the perivascular niche along the blood vessels, particularly at arterioles, at steady state. Moreover, we observed a reduced capacity of MCΔItgb1 to degranulate into the blood vessels during skin inflammation. In the CHS mouse model, MCΔItgb1 mice showed a dramatically reduced ear swelling, accompanied by a significant reduction of infiltrating neutrophils, monocytes, macrophages and CD8+ T cells in the ear skin. Notably, MCΔItgb1 mice exhibited an impaired activation of endothelial cells and a reduced immune cell extravasation from blood to the skin upon CHS. Furthermore, the lack of Itgb1 in MCs resulted in an impaired degranulation efficiency in vitro.
Conclusions: Our findings reveal the pivotal role of Itgb1 in MC distribution and perivascular alignment along the dermal blood vessels. Additionally, we highlight its significance in MC degranulation capacity and pro-inflammatory functions in CHS responses, suggesting a possible bidirectional cross-talk between ear skin MCs and blood endothelial cells.
The role of IRF8 in development and function of CD163-positive macrophage subpopulations
T. Jordan1, J. Roth1, K. Barczyk-Kahlert1
1University of Münster, Institute of Immunology, Münster, Germany
CD163 is a scavenger receptor, expressed exclusively by monocytes/macrophages and a widely accepted marker for anti inflammatory macrophages. CD163 was shown to dampen inflammatory responses, while enhancing the antimicrobial activity of monocytes/macrophages. The development of CD163-positive macrophages depends on the transcription factor interferon regulatory factor 8 (IRF8). IRF8-/- mice lack certain monocyte/macrophage subsets and have elevated serum levels of S100A8/A9 proteins. Using conventional (IRF8-/-) and myeloid lineage-specific conditional IRF8-knockout (IRF8flox LysMCre) mouse models, we investigated the influence of IRF8 on the expression of CD163 in different macrophage subpopulations by flow cytometry, immunofluorescence microscopy and Western blot analysis. The results obtained demonstrated significant alterations in immune cell populations in the bone marrow and peritoneal cavity of IRF8-/- mice, compared to wt and IRF8flox-LysMCre mice. While the proportion of CD163-positive macrophage subpopulations was significantly decreased or absent in the bone marrow, spleen and liver of IRF8-/- mice, deletion of IRF8 led to an increase in CD163-positive macrophage subpopulations in the peritoneal cavity. This coincided with an altered immune response of peritoneal macrophages to LPS stimulation in vitro. These findings indicate that the development and function of CD163- positive macrophage subpopulations is not solely dependent on the expression of IRF8 but also appears to be influenced by the environmental milieu.
Figure 1. Immunofluorescence analysis of F4/80 (red) and CD163 (green) expression in peritoneal cells (PC), spleen and liver of wt, IRF8-/- and IRF8flox-LysMCre mice.
