Publications by authors named "Jill Moser"

42 Publications

Comparison of renal histopathology and gene expression profiles between severe COVID-19 and bacterial sepsis in critically ill patients.

Crit Care 2021 Jun 10;25(1):202. Epub 2021 Jun 10.

Department of Critical Care, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.

Background: The mechanisms driving acute kidney injury (AKI) in critically ill COVID-19 patients are unclear. We collected kidney biopsies from COVID-19 AKI patients within 30 min after death in order to examine the histopathology and perform mRNA expression analysis of genes associated with renal injury.

Methods: This study involved histopathology and mRNA analyses of postmortem kidney biopsies collected from patients with COVID-19 (n = 6) and bacterial sepsis (n = 27). Normal control renal tissue was obtained from patients undergoing total nephrectomy (n = 12). The mean length of ICU admission-to-biopsy was 30 days for COVID-19 and 3-4 days for bacterial sepsis patients.

Results: We did not detect SARS-CoV-2 RNA in kidney biopsies from COVID-19-AKI patients yet lung tissue from the same patients was PCR positive. Extensive acute tubular necrosis (ATN) and peritubular thrombi were distinct histopathology features of COVID-19-AKI compared to bacterial sepsis-AKI. ACE2 mRNA levels in both COVID-19 (fold change 0.42, p = 0.0002) and bacterial sepsis patients (fold change 0.24, p < 0.0001) were low compared to control. The mRNA levels of injury markers NGAL and KIM-1 were unaltered compared to control tissue but increased in sepsis-AKI patients. Markers for inflammation and endothelial activation were unaltered in COVID-19 suggesting a lack of renal inflammation. Renal mRNA levels of endothelial integrity markers CD31, PV-1 and VE-Cadherin did not differ from control individuals yet were increased in bacterial sepsis patients (CD31 fold change 2.3, p = 0.0006, PV-1 fold change 1.5, p = 0.008). Angiopoietin-1 mRNA levels were downregulated in renal tissue from both COVID-19 (fold change 0.27, p < 0.0001) and bacterial sepsis patients (fold change 0.67, p < 0.0001) compared to controls. Moreover, low Tie2 mRNA expression (fold change 0.33, p = 0.037) and a disturbed VEGFR2/VEGFR3 ratio (fold change 0.09, p < 0.0001) suggest decreased microvascular flow in COVID-19.

Conclusions: In a small cohort of postmortem kidney biopsies from COVID-19 patients, we observed distinct histopathological and gene expression profiles between COVID-19-AKI and bacterial sepsis-AKI. COVID-19 was associated with more severe ATN and microvascular thrombosis coupled with decreased microvascular flow, yet minimal inflammation. Further studies are required to determine whether these observations are a result of true pathophysiological differences or related to the timing of biopsy after disease onset.
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http://dx.doi.org/10.1186/s13054-021-03631-4DOI Listing
June 2021

Sepsis is associated with mitochondrial DNA damage and a reduced mitochondrial mass in the kidney of patients with sepsis-AKI.

Crit Care 2021 01 25;25(1):36. Epub 2021 Jan 25.

Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, P.O. Box 30.001, EB70, 9700 RB, Groningen, The Netherlands.

Background: Sepsis is a life-threatening condition accompanied by organ dysfunction subsequent to a dysregulated host response to infection. Up to 60% of patients with sepsis develop acute kidney injury (AKI), which is associated with a poor clinical outcome. The pathophysiology of sepsis-associated AKI (sepsis-AKI) remains incompletely understood, but mitochondria have emerged as key players in the pathogenesis. Therefore, our aim was to identify mitochondrial damage in patients with sepsis-AKI.

Methods: We conducted a clinical laboratory study using "warm" postmortem biopsies from sepsis-associated AKI patients from a university teaching hospital. Biopsies were taken from adult patients (n = 14) who died of sepsis with AKI at the intensive care unit (ICU) and control patients (n = 12) undergoing tumor nephrectomy. To define the mechanisms of the mitochondrial contribution to the pathogenesis of sepsis-AKI, we explored mRNA and DNA expression of mitochondrial quality mechanism pathways, DNA oxidation and mitochondrial DNA (mtDNA) integrity in renal biopsies from sepsis-AKI patients and control subjects. Next, we induced human umbilical vein endothelial cells (HUVECs) with lipopolysaccharide (LPS) for 48 h to mimic sepsis and validate our results in vitro.

Results: Compared to control subjects, sepsis-AKI patients had upregulated mRNA expression of oxidative damage markers, excess mitochondrial DNA damage and lower mitochondrial mass. Sepsis-AKI patients had lower mRNA expression of mitochondrial quality markers TFAM, PINK1 and PARKIN, but not of MFN2 and DRP1. Oxidative DNA damage was present in the cytosol of tubular epithelial cells in the kidney of sepsis-AKI patients, whereas it was almost absent in biopsies from control subjects. Oxidative DNA damage co-localized with both the nuclei and mitochondria. Accordingly, HUVECs induced with LPS for 48 h showed an increased mnSOD expression, a decreased TFAM expression and higher mtDNA damage levels.

Conclusion: Sepsis-AKI induces mitochondrial DNA damage in the human kidney, without upregulation of mitochondrial quality control mechanisms, which likely resulted in a reduction in mitochondrial mass.
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http://dx.doi.org/10.1186/s13054-020-03424-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7831178PMC
January 2021

Pharmacological inhibition of focal adhesion kinase 1 (FAK1) and anaplastic lymphoma kinase (ALK) identified via kinome profile analysis attenuates lipopolysaccharide-induced endothelial inflammatory activation.

Biomed Pharmacother 2021 Jan 13;133:111073. Epub 2020 Dec 13.

Department of Pathology and Medical Biology, Medical Biology Section, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. Electronic address:

Sepsis is a life-threatening condition often leading to multiple organ failure for which currently no pharmacological treatment is available. Endothelial cells (EC) are among the first cells to respond to pathogens and inflammatory mediators in sepsis and might be a sentinel target to prevent the occurrence of multiple organ failure. Lipopolysaccharide (LPS) is a Gram-negative bacterial component that induces endothelial expression of inflammatory adhesion molecules, cytokines, and chemokines. This expression is regulated by a network of kinases, the result of which in vivo enables leukocytes to transmigrate from the blood into the underlying tissue, causing organ damage. We hypothesised that besides the known kinase pathways, other kinases are involved in the regulation of EC in response to LPS, and that these can be pharmacologically targeted to inhibit cell activation. Using kinome profiling, we identified 58 tyrosine kinases (TKs) that were active in human umbilical vein endothelial cells (HUVEC) at various timepoints after stimulation with LPS. These included AXL tyrosine kinase (Axl), focal adhesion kinase 1 (FAK1), and anaplastic lymphoma kinase (ALK). Using siRNA-based gene knock down, we confirmed that these three TKs mediate LPS-induced endothelial inflammatory activation. Pharmacological inhibition with FAK1 inhibitor FAK14 attenuated LPS-induced endothelial inflammatory activation and leukocyte adhesion partly via blockade of NF-κB activity. Administration of FAK14 after EC exposure to LPS also resulted in inhibition of inflammatory molecule expression. In contrast, inhibition of ALK with FDA-approved inhibitor Ceritinib attenuated LPS-induced endothelial inflammatory activation via a pathway that was independent of NF-κB signalling while it did not affect leukocyte adhesion. Furthermore, Ceritinib administration after start of EC exposure to LPS did not inhibit inflammatory activation. Combined FAK1 and ALK inhibition attenuated LPS-induced endothelial activation in an additive manner, without affecting leukocyte adhesion. Summarising, our findings suggest the involvement of FAK1 and ALK in mediating LPS-induced inflammatory activation of EC. Since pharmacological inhibition of FAK1 attenuated endothelial inflammatory activation after the cells were exposed to LPS, FAK1 represents a promising target for follow up studies.
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http://dx.doi.org/10.1016/j.biopha.2020.111073DOI Listing
January 2021

Acute Kidney Injury is Associated with Lowered Plasma-Free Thiol Levels.

Antioxidants (Basel) 2020 Nov 16;9(11). Epub 2020 Nov 16.

Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, 9713GZ Groningen, The Netherlands.

Acute kidney injury (AKI) is associated with the abrupt loss of kidney function. Oxidative stress plays an important role in the pathophysiology of AKI. Free thiols (R-SH) are crucial components of the extracellular antioxidant machinery and reliably reflect systemic oxidative stress. Lower levels of thiols represent higher levels of oxidative stress. In this preliminary study, we hypothesized that plasma-free thiols are associated with AKI upon admission to the intensive care unit (ICU). In this study, 301 critically ill patients were included. Plasma samples were taken upon admission, and albumin-adjusted plasma-free thiols were determined. Albumin-adjusted plasma-free thiols were lower in patients with AKI (n = 43, median (interquartile range) 7.28 µmol/g (3.52, 8.95)) compared to patients without AKI (8.50 μmol/g (5.82, 11.28); < 0.05) upon admission to the ICU. Higher age (B = -0.72), higher levels of neutrophil gelatinase-associated lipocalin (B = -0.002), creatinine (B = -0.01) and lower serum albumin (B = 0.47) were associated with lower free thiol levels. Further, albumin-adjusted free thiol levels were significantly reduced in patients with sepsis (8.30 (5.52-10.64) µmol/g) compared to patients without sepsis (6.95 (3.72-8.92) µmol/g; < 0.05). Together, albumin-adjusted plasma-free thiols were significantly reduced in patients with AKI and patients with sepsis compared with patients without AKI and sepsis.
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http://dx.doi.org/10.3390/antiox9111135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696918PMC
November 2020

Post-Mortem Diagnostics in COVID-19 AKI, More Often but Timely.

J Am Soc Nephrol 2021 01 5;32(1):255. Epub 2020 Nov 5.

Department of Pathology and Medical Biology, Medical Biology Section, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

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http://dx.doi.org/10.1681/ASN.2020091263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7894667PMC
January 2021

Understanding immunopathology of severe dengue: lessons learnt from sepsis.

Curr Opin Virol 2020 08 4;43:41-49. Epub 2020 Sep 4.

Department of Medical Microbiology and Infection Prevention, University of Groningen and University Medical Center Groningen, 9700 RB Groningen, The Netherlands. Electronic address:

Endothelial dysfunction leading to vascular permeability and plasma leakage are characteristic features of severe dengue and sepsis. However, the mechanisms underlying these immune-pathologies remain unclear. The risk of severe dengue and sepsis development depend on patient-related and pathogen-related factors. Additionally, comorbidities increase the risk of severe disease and their incidence hampers correct diagnosis and treatments. To date, there is no efficient therapy to combat severe dengue and sepsis. Here, we discuss the differences and similarities between the pathogenesis of severe dengue and that of bacterial sepsis. We identify gaps in knowledge that need to be better understood in order to move towards the rational development and/or usage of therapeutic strategies to ameliorate severe dengue disease.
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http://dx.doi.org/10.1016/j.coviro.2020.07.010DOI Listing
August 2020

Leptin levels in SARS-CoV-2 infection related respiratory failure: A cross-sectional study and a pathophysiological framework on the role of fat tissue.

Heliyon 2020 Aug 20;6(8):e04696. Epub 2020 Aug 20.

Department of Critical Care, University of Groningen, University Medical Center Groningen, 9700, RB, Groningen, the Netherlands.

Obesity is a risk factor for SARS-CoV-2 infected patients to develop respiratory failure. Leptin produced in visceral fat might play a role in the deterioration to mechanical ventilation. A cross sectional study was performed. The mean BMI was 31 kg/m (range 24.8-48.4) for the 31 SARS-CoV-2 ventilated patients and 26 kg/m (range 22.4-33.5) for 8 critically ill non-infected control patients. SARS-CoV-2 infected patients with a similar BMI as control patients appear to have significantly higher levels of serum leptin. The mean leptin level was 21.2 (6.0-85.2) vs 5.6 (2.4-8.2) ug/L for SARS-CoV-2 and controls respectively (p = 0.0007). With these findings we describe a clinical and biological framework that may explain these clinical observations. The ACE2 utilization by the virus leads to local pulmonary inflammation due to ACE2-ATII disbalance. This might be enhanced by an increase in leptin production induced by SARS-CoV-2 infection of visceral fat. Leptin receptors in the lungs are now more activated to enhance local pulmonary inflammation. This adds to the pre-existent chronic inflammation in obese patients. Visceral fat, lung tissue and leptin production play an interconnecting role. This insight can lead the way to further research and treatment.
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http://dx.doi.org/10.1016/j.heliyon.2020.e04696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7439829PMC
August 2020

TLR2 on blood monocytes senses dengue virus infection and its expression correlates with disease pathogenesis.

Nat Commun 2020 06 23;11(1):3177. Epub 2020 Jun 23.

Department of Medical Microbiology and Infection Prevention, University of Groningen and University Medical Center Groningen, 9700, RB, Groningen, The Netherlands.

Vascular permeability and plasma leakage are immune-pathologies of severe dengue virus (DENV) infection, but the mechanisms underlying the exacerbated inflammation during DENV pathogenesis are unclear. Here, we demonstrate that TLR2, together with its co-receptors CD14 and TLR6, is an innate sensor of DENV particles inducing inflammatory cytokine expression and impairing vascular integrity in vitro. Blocking TLR2 prior to DENV infection in vitro abrogates NF-κB activation while CD14 and TLR6 block has a moderate effect. Moreover, TLR2 block prior to DENV infection of peripheral blood mononuclear cells prevents activation of human vascular endothelium, suggesting a potential role of the TLR2-responses in vascular integrity. TLR2 expression on CD14 + + classical monocytes isolated in an acute phase from DENV-infected pediatric patients correlates with severe disease development. Altogether, these data identify a role for TLR2 in DENV infection and provide insights into the complex interaction between the virus and innate receptors that may underlie disease pathogenesis.
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http://dx.doi.org/10.1038/s41467-020-16849-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311456PMC
June 2020

AKI: an enlightening acronym with a shadow side.

Kidney Int 2020 06;97(6):1301

Department of Pathology and Medical Biology, Medical Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Critical Care, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

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http://dx.doi.org/10.1016/j.kint.2020.03.016DOI Listing
June 2020

Heterogenous Renal Injury Biomarker Production Reveals Human Sepsis-Associated Acute Kidney Injury Subtypes.

Crit Care Explor 2019 Oct 14;1(10):e0047. Epub 2019 Oct 14.

Department of Critical Care, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

To identify mechanisms associated with sepsis-acute kidney injury based on the expression levels of renal injury biomarkers, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 in renal biopsies which may allow the identification of sepsis-acute kidney injury patient subtypes.

Design: Prospective, clinical laboratory study using "warm" human postmortem sepsis-acute kidney injury kidney biopsies.

Setting: Research laboratory at university teaching hospital.

Subjects: Adult patients who died of sepsis in the ICU and control patients undergoing tumor nephrectomy.

Measurements And Main Results: Reverse transcription quantitative polymerase chain reaction and immunohistochemical staining were used to quantify messenger RNA and protein expression levels of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in the kidney of sepsis-acute kidney injury patients and control subjects. Morphometric analysis was used to quantify renal and glomerular neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 protein levels. Neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 messenger RNA and protein levels were increased in kidneys of sepsis-acute kidney injury patients compared with control kidney tissue. Neutrophil gelatinase-associated lipocalin was localized in the distal tubules, collecting ducts, the adventitia of the renal arterioles, and in the glomerular tufts of renal biopsies from sepsis-acute kidney injury patients. In contrast, kidney injury molecule-1 was localized at the brush border of the proximal tubules. There was no correlation between neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 levels. Furthermore, renal neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 levels were not associated with the extent of renal injury, the severity of critical illness, or serum creatinine levels at either ICU admission or day of expiration. By laser microdissecting glomeruli, followed by reverse transcription quantitative polymerase chain reaction, we identified heterogenous glomerular neutrophil gelatinase-associated lipocalin production in the kidney of sepsis-acute kidney injury patients.

Conclusion: We found differences in the expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in patients with the same syndrome "sepsis-acute kidney injury" meaning there is no single pathway leading to sepsis-acute kidney injury. This underscores the beliefs that there are many/different pathophysiological pathways that can cause sepsis-acute kidney injury. Hence, patients with criteria that meet the definitions of both acute kidney injury and sepsis can be divided into subtypes based on pathophysiological features.
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http://dx.doi.org/10.1097/CCE.0000000000000047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7063889PMC
October 2019

Leukocyte-Released Mediators in Response to Both Bacterial and Fungal Infections Trigger IFN Pathways, Independent of IL-1 and TNF-α, in Endothelial Cells.

Front Immunol 2019 25;10:2508. Epub 2019 Oct 25.

Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.

In sepsis, dysregulated immune responses to infections cause damage to the host. Previous studies have attempted to capture pathogen-induced leukocyte responses. However, the impact of mediators released after pathogen-leukocyte interaction on endothelial cells, and how endothelial cell responses vary depending on the pathogen-type is lacking. Here, we comprehensively characterized the transcriptomic responses of human leukocytes and endothelial cells to Gram negative-bacteria, Gram positive-bacteria, and fungi. We showed that whole pathogen lysates induced strong activation of leukocytes but not endothelial cells. Interestingly, the common response of leukocytes to various pathogens converges on endothelial activation. By exposing endothelial cells to leukocyte-released mediators, we observed a strong activation of endothelial cells at both transcription and protein levels. By adding IL-1RA and TNF-α antibody in leukocyte-released mediators before exposing to endothelial cells, we identified specific roles for IL-1 and TNF-α in driving the most, but not all, endothelial activation. We also showed for the first time, activation of interferon response by endothelial cells in response to leukocyte-released mediators, independently from IL-1 and TNF-α pathways. Our study therefore, not only provides pathogen-dependent transcriptional changes in leukocytes and endothelial cells during infections, but also reveals a role for IFN, together with IL1 and TNFα signaling, in mediating leukocyte-endothelial interaction in infections.
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http://dx.doi.org/10.3389/fimmu.2019.02508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6824321PMC
November 2020

Identifying Sepsis Phenotypes.

JAMA 2019 10;322(14):1416

Department of Critical Care, University Medical Center Groningen, Groningen, the Netherlands.

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http://dx.doi.org/10.1001/jama.2019.12587DOI Listing
October 2019

Functional Annotation of Genetic Loci Associated With Sepsis Prioritizes Immune and Endothelial Cell Pathways.

Front Immunol 2019 14;10:1949. Epub 2019 Aug 14.

University of Groningen, University Medical Center Groningen, Genetics Department, Groningen, Netherlands.

Due to limited sepsis patient cohort size and extreme heterogeneity, only one significant locus and suggestive associations at several independent loci were implicated by three genome-wide association studies. However, genes from such suggestive loci may also provide crucial information to unravel genetic mechanisms that determine sepsis heterogeneity. Therefore, in this study, we made use of integrative approaches to prioritize genes and pathways affected by sepsis associated genetic variants. By integrating expression quantitative trait loci (eQTL) results from the largest whole-blood eQTL database, cytokine QTLs from pathogen-stimulated peripheral blood mononuclear cells (PBMCs), publicly available blood transcriptome data from pneumoniae-derived sepsis patients, and transcriptome data from pathogen-stimulated PBMCs, we identified 55 potential genes affected by 39 independent loci. By performing pathway enrichment analysis at these loci we found enrichment of genes for adherences-junction pathway. Finally, we investigated the functional role of the only one GWAS significant SNP rs4957796 on sepsis survival in altering transcription factor binding affinity in monocytes and endothelial cells. We also found that transient deficiency of and affect endothelial response to stimulation, indicating that both and could be the causal genes at this locus. Taken together, our study suggests that in addition to immune pathways, genetic variants may also affect non-immune related pathways.
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http://dx.doi.org/10.3389/fimmu.2019.01949DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703137PMC
October 2020

Identification of LPS-Activated Endothelial Subpopulations With Distinct Inflammatory Phenotypes and Regulatory Signaling Mechanisms.

Front Immunol 2019 24;10:1169. Epub 2019 May 24.

Medical Biology Section, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.

Sepsis is a life-threatening condition caused by a dysregulated host response to infection. Endothelial cells (EC) are actively involved in sepsis-associated (micro)vascular disturbances and subsequent organ dysfunction. Lipopolysaccharide (LPS), a Gram-negative bacterial product, can activate EC leading to the expression of pro-inflammatory molecules. This process is molecularly regulated by specific receptors and distinct, yet poorly understood intracellular signaling pathways. LPS-induced expression of endothelial adhesion molecules E-selectin and VCAM-1 in mice was previously shown to be organ- and microvascular-specific. Here we report that also within renal microvascular beds the endothelium expresses different extents of E-selectin and VCAM-1. This heterogeneity was recapitulated in LPS-activated human umbilical vein EC (HUVEC). Within 2 h after LPS exposure, four distinct HUVEC subpopulations were visible by flow cytometric analysis detecting E-selectin and VCAM-1 protein. These encompassed E-selectin/VCAM-1 (-/-), E-selectin/VCAM-1 (E-sel+), E-selectin/VCAM-1 (+/+), and E-selectin/VCAM-1 (VCAM-1+) subpopulations. The formation of subpopulations was a common response of endothelial cells to LPS challenge. Using fluorescence-activated cell sorting (FACS) we demonstrated that the +/+ subpopulation also expressed the highest levels of inflammatory cytokines and chemokines. The differences in responsiveness of EC subpopulations could not be explained by differential expression of LPS receptors TLR4 and RIG-I. Functional studies, however, demonstrated that the formation of the E-sel+ subpopulation was mainly TLR4-mediated, while the formation of the +/+ subpopulation was mediated by both TLR4 and RIG-I. Pharmacological blockade of NF-κB and p38 MAPK furthermore revealed a prominent role of their signaling cascades in E-sel+ and +/+ subpopulation formation. In contrast, the VCAM-1+ subpopulation was not controlled by any of these signaling pathways. Noteworthy is the existence of a "quiescent" subpopulation that was devoid of the two adhesion molecules and did not express cytokines or chemokines despite LPS exposure. Summarizing, our findings suggest that LPS activates different signaling mechanisms in EC that drive heterogeneous expression of EC inflammatory molecules. Further characterization of the signaling pathways involved will enhance our understanding of endothelial heterogeneous responses to sepsis related stimuli and enable the future design of effective therapeutic strategies to interfere in these processes to counteract sepsis-associated organ dysfunction.
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http://dx.doi.org/10.3389/fimmu.2019.01169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543489PMC
September 2020

Commentary: Precision Immunotherapy for Sepsis.

Front Immunol 2019;10:20. Epub 2019 Jan 31.

Department of Critical Care, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.

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http://dx.doi.org/10.3389/fimmu.2019.00020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6365442PMC
July 2019

Kidney histopathology in lethal human sepsis.

Crit Care 2018 12 27;22(1):359. Epub 2018 Dec 27.

Department of Critical Care, University of Groningen, University Medical Center Groningen, P.O. 30.001, Hanzeplein 1, 9700 RB, Groningen, Netherlands.

Purpose: The histopathology of sepsis-associated acute kidney injury (AKI) in critically ill patients remains an understudied area. Previous studies have identified that acute tubular necrosis (ATN) is not the only driver of sepsis-AKI. The focus of this study was to identify additional candidate processes that may drive sepsis-AKI. To do this we immunohistochemically characterized the histopathological and cellular features in various compartments of human septic kidneys.

Methods: We studied the following histopathological features: leukocyte subsets, fibroblast activation, cellular proliferation, apoptosis, and fibrin deposition in the glomerulus and the tubulointerstitium in human post-mortem kidney biopsy tissue. Biopsy tissue samples from 27 patients with sepsis-AKI were collected 33 min (range 24-150) after death in the ICU. The unaffected part of the kidneys from 12 patients undergoing total nephrectomy as a result of renal carcinoma served as controls.

Results: Immunohistochemical analysis revealed the presence of more neutrophils and macrophages in the glomeruli and more neutrophils in the tubulointerstitium of renal tissue from patients with sepsis compared to control renal tissue. Type II macrophages were predominant, with some macrophages expressing both type I and type II markers. In contrast, there were almost no macrophages found in control kidneys. The number of activated (myo)fibroblasts was low in the glomeruli of sepsis-AKI kidneys, yet this was not observed in the tubulointerstitium. Cell proliferation and fibrin deposition were more pronounced in the glomeruli and tubulointerstitium of sepsis-AKI than in control kidneys.

Conclusions: The extensive heterogeneity of observations among and within patients emphasizes the need to thoroughly characterize patients with sepsis-AKI in a large sample of renal biopsy tissue from patients with sepsis.
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http://dx.doi.org/10.1186/s13054-018-2287-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6307291PMC
December 2018

Partial Deletion of Tie2 Affects Microvascular Endothelial Responses to Critical Illness in A Vascular Bed and Organ-Specific Way.

Shock 2019 06;51(6):757-769

Department of Pathology and Medical Biology, Medical Biology Section, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Tyrosine kinase receptor (Tie2) is mainly expressed by endothelial cells. In animal models mimicking critical illness, Tie2 levels in organs are temporarily reduced. Functional consequences of these reduced Tie2 levels on microvascular endothelial behavior are unknown. We investigated the effect of partial deletion of Tie2 on the inflammatory status of endothelial cells in different organs. Newly generated heterozygous Tie2 knockout mice (exon 9 deletion, ΔE9/Tie2) exhibiting 50% reduction in Tie2 mRNA and protein, and wild-type littermate controls (Tie2), were subjected to hemorrhagic shock and resuscitation (HS + R), or challenged with i.p. lipopolysaccharide (LPS). Kidney, liver, lung, heart, brain, and intestine were analyzed for mRNA levels of adhesion molecules E-selectin, vascular cell adhesion molecule 1 (VCAM-1), and intercellular cell adhesion molecule 1 (ICAM-1), and CD45. Exposure to HS + R did not result in different expression responses of these molecules between organs from Tie2 or Tie2 mice and sham-operated mice. In contrast, the LPS-induced mRNA expression levels of E-selectin, VCAM-1, and ICAM-1, and CD45 in organs were attenuated in Tie2 mice when compared with Tie2 mice in kidney and liver, but not in the other organs studied. Furthermore, reduced expression of E-selectin and VCAM-1 protein, and reduced influx of CD45 cells upon LPS exposure, was visible in a microvascular bed-specific pattern in kidney and liver of Tie2 mice compared with controls. In contrast to the hypothesis that a disbalance in the Ang/Tie2 system leads to increased microvascular inflammation, heterozygous deletion of Tie2 is associated with an organ-restricted, microvascular bed-specific attenuation of endothelial inflammatory response to LPS.
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http://dx.doi.org/10.1097/SHK.0000000000001226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511431PMC
June 2019

Renal Klotho is Reduced in Septic Patients and Pretreatment With Recombinant Klotho Attenuates Organ Injury in Lipopolysaccharide-Challenged Mice.

Crit Care Med 2018 12;46(12):e1196-e1203

Department of Critical Care, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Objectives: To determine the applicability of recombinant Klotho to prevent inflammation and organ injury in sepsis in man and mice.

Design: Prospective, clinical laboratory study using "warm" human postmortem sepsis-acute kidney injury biopsies. Laboratory study using a mouse model of endotoxemia.

Setting: Research laboratory at a university teaching hospital.

Subjects: Adult patients who died of sepsis in the ICU and control patients undergoing total nephrectomy secondary to renal cancer; male C57BL/6 and Klotho haploinsufficient mice.

Interventions: Lipopolysaccharide (0.05 mg/kg) injection and kill after 4, 8, and 24 hours. Mice received recombinant Klotho (0.05 mg/kg) 30 minutes prior to lipopolysaccharide (1 mg/kg) injection. Mice treated with saline were included as controls.

Measurements And Main Results: Quantitative reverse transcription polymerase chain reaction and immunohistochemical staining were used to quantify Klotho messenger RNA and protein expression in the kidney of sepsis-acute kidney injury patients and the kidney and brain of mice. The messenger RNA and protein expression of damage markers, inflammatory cytokine, chemokines, and endothelial adhesion molecules were also determined in mice. Renal neutrophil influx was quantified. We found significantly lower renal Klotho messenger RNA and protein levels in sepsis-acute kidney injury biopsies than in control subjects. These findings were recapitulated in the kidney and brain of lipopolysaccharide-challenged mice. Decreased Klotho expression paralleled an increase in kidney damage markers neutrophil gelatinase-associated lipocalin and kidney injury molecule-1. Administration of recombinant Klotho prior to lipopolysaccharide injection attenuated organ damage, inflammation and endothelial activation in the kidney and brain of mice. Furthermore, less neutrophils infiltrated into the kidneys of recombinant Klotho mice compared with lipopolysaccharide only treated mice.

Conclusions: Renal Klotho expression in human sepsis-acute kidney injury and in mouse models of sepsis was significantly decreased and correlated with renal damage. Recombinant Klotho intervention diminished organ damage, inflammation, and endothelial activation in the kidney and brain of lipopolysaccharide-challenged mice. Systemic Klotho replacement may potentially be an organ-protective therapy for septic patients to halt acute, inflammatory organ injury.
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http://dx.doi.org/10.1097/CCM.0000000000003427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6250245PMC
December 2018

Low-Fat Diet With Caloric Restriction Reduces White Matter Microglia Activation During Aging.

Front Mol Neurosci 2018 12;11:65. Epub 2018 Mar 12.

Department of Neuroscience, Medical Physiology Section, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.

Rodent models of both aging and obesity are characterized by inflammation in specific brain regions, notably the corpus callosum, fornix, and hypothalamus. Microglia, the resident macrophages of the central nervous system, are important for brain development, neural support, and homeostasis. However, the effects of diet and lifestyle on microglia during aging are only partly understood. Here, we report alterations in microglia phenotype and functions in different brain regions of mice on a high-fat diet (HFD) or low-fat diet (LFD) during aging and in response to voluntary running wheel exercise. We compared the expression levels of genes involved in immune response, phagocytosis, and metabolism in the hypothalamus of 6-month-old HFD and LFD mice. We also compared the immune response of microglia from HFD or LFD mice to peripheral inflammation induced by intraperitoneal injection of lipopolysaccharide (LPS). Finally, we investigated the effect of diet, physical exercise, and caloric restriction (40% reduction compared to intake) on microglia in 24-month-old HFD and LFD mice. Changes in diet caused morphological changes in microglia, but did not change the microglia response to LPS-induced systemic inflammation. Expression of phagocytic markers (i.e., Mac-2/Lgals3, Dectin-1/Clec7a, and CD16/CD32) in the white matter microglia of 24-month-old brain was markedly decreased in calorically restricted LFD mice. In conclusion, LFD resulted in reduced activation of microglia, which might be an underlying mechanism for the protective role of caloric restriction during aging-associated decline.
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http://dx.doi.org/10.3389/fnmol.2018.00065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857900PMC
March 2018

Early Heterogenic Response of Renal Microvasculature to Hemorrhagic Shock/Resuscitation and the Influence of NF-κB Pathway Blockade.

Shock 2019 02;51(2):200-212

Department of Pathology and Medical Biology, Medical Biology Section, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Hemorrhagic shock (HS) is associated with low blood pressure due to excessive loss of circulating blood and causes both macrocirculatory and microcirculatory dysfunction. Fluid resuscitation after HS is used in the clinic to restore tissue perfusion. The persistent microcirculatory damage caused by HS and/or resuscitation can result in multiple organ damage, with the kidney being one of the involved organs. The kidney microvasculature consists of different segments that possess a remarkable heterogeneity in functional properties. The aim of this study was to investigate the inflammatory responses of these different renal microvascular segments, i.e., arterioles, glomeruli, and postcapillary venules, to HS and resuscitation (HS/R) in mice and to explore the effects of intervention with a nuclear factor-kappa B (NF-κB) inhibitor on these responses. We found that HS/R disturbed the balance of the angiopoietin-Tie2 ligand-receptor system, especially in the glomeruli. Furthermore, endothelial adhesion molecules, proinflammatory cytokines, and chemokines were markedly upregulated by HS/R, with the strongest responses occurring in the glomerular and postcapillary venous segments. Blockade of NF-κB signaling during the resuscitation period only slightly inhibited HS/R-induced inflammatory activation, possibly because NF-κB p65 nuclear translocation already occurred during the HS period. In summary, although all three renal microvascular segments were activated upon HS/R, responses of endothelial cells in glomeruli and postcapillary venules to HS/R, as well as to NF-κB inhibition were stronger than those in arterioles. NF-κB inhibition during the resuscitation phase does not effectively counteract NF-κB p65 nuclear translocation initiating inflammatory gene transcription.
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http://dx.doi.org/10.1097/SHK.0000000000001126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6319598PMC
February 2019

Human alternative Klotho mRNA is a nonsense-mediated mRNA decay target inefficiently spliced in renal disease.

JCI Insight 2017 10 19;2(20). Epub 2017 Oct 19.

Department of Pathology and Medical Biology (Division of Pathology), University of Groningen, University Medical Center Groningen (UMCG), Groningen, The Netherlands.

Klotho is a renal protein involved in phosphate homeostasis, which is downregulated in renal disease. It has long been considered an antiaging factor. Two Klotho gene transcripts are thought to encode membrane-bound and secreted Klotho. Indeed, soluble Klotho is detectable in bodily fluids, but the relative contributions of Klotho secretion and of membrane-bound Klotho shedding are unknown. Recent advances in RNA surveillance reveal that premature termination codons, as present in alternative Klotho mRNA (for secreted Klotho), prime mRNAs for degradation by nonsense-mediated mRNA decay (NMD). Disruption of NMD led to accumulation of alternative Klotho mRNA, indicative of normally continuous degradation. RNA IP for NMD core factor UPF1 resulted in enrichment for alternative Klotho mRNA, which was also not associated with polysomes, indicating no active protein translation. Alternative Klotho mRNA transcripts colocalized with some P bodies, where NMD transcripts are degraded. Moreover, we could not detect secreted Klotho in vitro. These results suggest that soluble Klotho is likely cleaved membrane-bound Klotho only. Furthermore, we found that, especially in acute kidney injury, splicing of the 2 mRNA transcripts is dysregulated, which was recapitulated by various noxious stimuli in vitro. This likely constitutes a novel mechanism resulting in the downregulation of membrane-bound Klotho.
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http://dx.doi.org/10.1172/jci.insight.94375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5846909PMC
October 2017

Endothelial Interferon Regulatory Factor 1 Regulates Lipopolysaccharide-Induced VCAM-1 Expression Independent of NFκB.

J Innate Immun 2017 29;9(6):546-560. Epub 2017 Jun 29.

Medical Biology Section, Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Sepsis is a severe systemic inflammatory response to infection. Endothelial activation and dysfunction play a critical role in the pathophysiology of sepsis and represent an important therapeutic target to reduce sepsis mortality. Interferon regulatory factor 1 (IRF-1) was recently identified as a downstream target of TNF-α-mediated signal transduction in endothelial cells. The aim of this study was to explore the importance of IRF-1 as a regulator of lipopolysaccharide (LPS)-induced endothelial proinflammatory activation. We found that renal IRF-1 was upregulated by LPS in vivo as well as in LPS-stimulated endothelial cells in vitro. Furthermore, we identified intracellular retinoic acid inducible gene-I (RIG-I) as a regulator of LPS-mediated IRF-1 induction. IRF-1 depletion specifically resulted in diminished induction of VCAM-1 in response to LPS, but not of E-selectin or ICAM-1, which was independent of NFκB signaling. When both IRF-1 and the RIG-I adapter protein mitochondrial antiviral signaling (MAVS) were absent, VCAM-1 induction was not additionally inhibited, suggesting that MAVS and IRF-1 reside in the same signaling pathway. Surprisingly, E-selectin and IL-6 induction were no longer inhibited by MAVS knockdown when IRF-1 was also absent, revealing a redundant endothelial activation pathway. In summary, we report an IRF-1-mediated proinflammatory signaling pathway that specifically regulates LPS-mediated VCAM-1 expression, independent of NFκB.
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http://dx.doi.org/10.1159/000477211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738826PMC
July 2018

There Are More Things in Heaven and Earth, Horatio, Than Are Dreamt of in Our Philosophy.

Crit Care Med 2017 07;45(7):e740

Department of Critical Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

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http://dx.doi.org/10.1097/CCM.0000000000002426DOI Listing
July 2017

Age-determined severity of anti-myeloperoxidase autoantibody-mediated glomerulonephritis in mice.

Nephrol Dial Transplant 2017 02;32(2):254-264

Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Background: Anti-neutrophil cytoplasmic antibody associated vasculitis (AAV) is a typical disease of the elderly. In AAV, there is an age-specific increase in disease incidence with age being a predictor of disease outcome. In this study, we aimed to determine the contribution of age to the development of AAV employing a mouse model of anti-myeloperoxidase (MPO) antibody-mediated glomerulonephritis.

Methods: Anti-MPO IgG and lipopolysaccharide (LPS)-mediated glomerulonephritis was induced in 3- and 18-month-old C57Bl6 mice. Clinical and pathological parameters of disease severity, alterations in the immune system and kidney specific changes in these mice were evaluated.

Results: Eighteen-month-old mice developed increased disease severity upon injection of anti-MPO IgG/LPS compared with 3-month-old mice. This was evidenced by increased albuminuria, more extensive glomerular capillary necrosis and increased glomerular neutrophil accumulation. Glomerular crescent formation was mild in both young and old mice. Old mice displayed higher plasma interleukin-6 levels as well as higher proportions of circulating neutrophils and activated monocytes compared with young mice. In addition, renal mRNA levels of inflammatory genes and endothelial adhesion molecules were higher in 18-month-old mice compared with 3-month-old mice.

Conclusion: In conclusion, our results indicate that aged mice develop more severe clinical and pathological disease upon induction of anti-MPO IgG/LPS-mediated glomerulonephritis. These findings may be attributed to age-related changes in the immune system as well as in the kidney itself.
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http://dx.doi.org/10.1093/ndt/gfw202DOI Listing
February 2017

Organ-Specific Differences in Endothelial Permeability-Regulating Molecular Responses in Mouse and Human Sepsis.

Shock 2017 07;48(1):69-77

*Department of Critical Care, University Medical Center Groningen, University of Groningen, Groningen, Netherlands †Department of Pathology and Medical Biology, Medical Biology Section, University Medical Center Groningen, University of Groningen, Groningen, Netherlands ‡Department of Anaesthesiology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.

In patients with sepsis-induced multi-organ dysfunction syndrome, diverging patterns of oedema formation and loss of function in organs such as lung and kidney suggest that endothelial permeability-regulating molecular responses are differentially regulated. This potential differential regulation has been insufficiently studied at the level of components of adherens and tight junctions. We hypothesized that such a regulation by endothelial cells in sepsis takes place in an organ-specific manner. We addressed our hypothesis by studying by quantitative real time polymerase chain reaction the expression of a predefined subset of EC permeability-related molecules (occludin, claudin-5, PV-1, CD-31, endomucin, Angiopoietin-1, Angiopoietin-2, Tie2, VEGFA, VEGFR1, VEGFR2, and VE-cadherin) in kidney and lung after systemic lipopolysacharide injection in mice, and in kidneys of patients who died of sepsis. We showed that baseline endothelial expression of permeability-related molecules differs in mouse kidney and lung. Moreover, we showed differential regulation of these molecules after lipopolysacharide injection in the two mouse organs. In lung we found a decrease in expression levels of molecules of the adherence and tight junctions complex and related signaling systems, compatible with increased permeability. In contrast, in kidney we found expression patterns of these molecules compatible with decreased permeability. Finally, we partially corroborated our findings in mouse kidney in human kidneys from septic patients. These findings may help to understand the clinical difference in the extent of oedema formation in kidney and lung in sepsis-associated organ failure.
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http://dx.doi.org/10.1097/SHK.0000000000000841DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457831PMC
July 2017

Distinct Differences on Neointima Formation in Immunodeficient and Humanized Mice after Carotid or Femoral Arterial Injury.

Sci Rep 2016 10 19;6:35387. Epub 2016 Oct 19.

Department of Pathology and Medical Biology-Pathology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Percutaneous coronary intervention is widely adopted to treat patients with coronary artery disease. However, restenosis remains an unsolved clinical problem after vascular interventions. The role of the systemic and local immune response in the development of restenosis is not fully understood. Hence, the aim of the current study was to investigate the role of the human immune system on subsequent neointima formation elicited by vascular injury in a humanized mouse model. Immunodeficient NOD.Cg-PrkdcIL2rg(NSG) mice were reconstituted with human (h)PBMCs immediately after both carotid wire and femoral cuff injury were induced in order to identify how differences in the severity of injury influenced endothelial regeneration, neointima formation, and homing of human inflammatory and progenitor cells. In contrast to non-reconstituted mice, hPBMC reconstitution reduced neointima formation after femoral cuff injury whereas hPBMCs promoted neointima formation after carotid wire injury 4 weeks after induction of injury. Neointimal endothelium and smooth muscle cells in the injured arteries were of mouse origin. Our results indicate that the immune system may differentially respond to arterial injury depending on the severity of injury, which may also be influenced by the intrinsic properties of the arteries themselves, resulting in either minimal or aggravated neointima formation.
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http://dx.doi.org/10.1038/srep35387DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5069488PMC
October 2016

Intracellular RIG-I Signaling Regulates TLR4-Independent Endothelial Inflammatory Responses to Endotoxin.

J Immunol 2016 06 29;196(11):4681-91. Epub 2016 Apr 29.

Department of Critical Care, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, the Netherlands; Department of Pathology and Medical Biology, Medical Biology Section, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, the Netherlands;

Sepsis is a systemic inflammatory response to infections associated with organ failure that is the most frequent cause of death in hospitalized patients. Exaggerated endothelial activation, altered blood flow, vascular leakage, and other disturbances synergistically contribute to sepsis-induced organ failure. The underlying signaling events associated with endothelial proinflammatory activation are not well understood, yet they likely consist of molecular pathways that act in an endothelium-specific manner. We found that LPS, a critical factor in the pathogenesis of sepsis, is internalized by endothelial cells, leading to intracellular signaling without the need for priming as found recently in immune cells. By identifying a novel role for retinoic acid-inducible gene-I (RIG-I) as a central regulator of endothelial activation functioning independent of TLR4, we provide evidence that the current paradigm of TLR4 solely being responsible for LPS-mediated endothelial responses is incomplete. RIG-I, as well as the adaptor protein mitochondrial antiviral signaling protein, regulates NF-κB-mediated induction of adhesion molecules and proinflammatory cytokine expression in response to LPS. Our findings provide essential new insights into the proinflammatory signaling pathways in endothelial cells and suggest that combined endothelial-specific inhibition of RIG-I and TLR4 will provide protection from aberrant endothelial responses associated with sepsis.
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http://dx.doi.org/10.4049/jimmunol.1501819DOI Listing
June 2016

Reduced levels of cytosolic DNA sensor AIM2 are associated with impaired cytokine responses in healthy elderly.

Exp Gerontol 2016 Jun 2;78:39-46. Epub 2016 Mar 2.

Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands. Electronic address:

Objective: Human aging is associated with remodeling of the immune system. While most studies on immunosenescence have focused on adaptive immunity, the effects of aging on innate immunity are not well understood. Here, we investigated whether aging affects cytokine responses to a wide range of well-defined pattern recognition receptor (PRR) ligands, such as ligands for Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), retinoic-acid-inducible gene-I like receptors (RLRs) and the cytosolic DNA sensor absent in melanoma 2 (AIM2).

Method: Blood was collected from 16 young (20-39 years) and 18 elderly (60-84 years) healthy participants. Pro-inflammatory cytokine (TNF-α, IL-1β, IL-6, and IL-8) production in a whole blood assay (WBA) after stimulation with TLR ligands (Pam3csk4, poly(I:C), LPS, CpG), CLR ligand (β-glucan), NLR ligand (MDP), RLR ligands (5'ppp-dsDNA and poly(I:C)/lyovec) and the AIM2 ligand (poly(dA:dT) was assessed by ELISA. TLR2 and TLR4 expression by leukocytes and monocytes was determined by flow-cytometry. Expression of AIM2 by peripheral blood mononuclear cells (PBMC) was assessed by qRT-PCR and Western blot.

Result: Cytokine responses to Pam3csk4, poly(I:C) and CpG, β-glucan, MDP, 5'ppp-dsDNA and poly(I:C)/lyovec were comparable between young and old participants. We observed a higher IL-8 response following stimulation of elderly blood samples with the TLR4 ligand LPS, which was associated with higher proportions of TLR4 expressing monocytes. Interestingly, stimulation of whole blood cells with the AIM2 ligand poly(dA:dT) resulted in significantly lower cytokine responses in old participants. Moreover, these lower cytokine responses were associated with lower AIM2 protein expression and activation in PBMC of old participants.

Conclusion: Our findings reveal an age-dependent reduction of AIM2 expression and activation which may explain reduced cytokine responses to the cytosolic DNA mimic poly(dA:dT) in healthy elderly individuals. Reduced AIM2-mediated sensing with age may contribute to increased vulnerability to bacterial or viral infections in the elderly.
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http://dx.doi.org/10.1016/j.exger.2016.02.016DOI Listing
June 2016

Enhanced microglial pro-inflammatory response to lipopolysaccharide correlates with brain infiltration and blood-brain barrier dysregulation in a mouse model of telomere shortening.

Aging Cell 2015 Dec 3;14(6):1003-13. Epub 2015 Aug 3.

Section Medical Physiology, Department of Neuroscience, University of Groningen, University Medical Center Groningen, Groningen, 9713 AV, The Netherlands.

Microglia are a proliferative population of resident brain macrophages that under physiological conditions self-renew independent of hematopoiesis. Microglia are innate immune cells actively surveying the brain and are the earliest responders to injury. During aging, microglia elicit an enhanced innate immune response also referred to as 'priming'. To date, it remains unknown whether telomere shortening affects the proliferative capacity and induces priming of microglia. We addressed this issue using early (first-generation G1 mTerc(-/-) )- and late-generation (third-generation G3 and G4 mTerc(-/-) ) telomerase-deficient mice, which carry a homozygous deletion for the telomerase RNA component gene (mTerc). Late-generation mTerc(-/-) microglia show telomere shortening and decreased proliferation efficiency. Under physiological conditions, gene expression and functionality of G3 mTerc(-/-) microglia are comparable with microglia derived from G1 mTerc(-/-) mice despite changes in morphology. However, after intraperitoneal injection of bacterial lipopolysaccharide (LPS), G3 mTerc(-/-) microglia mice show an enhanced pro-inflammatory response. Nevertheless, this enhanced inflammatory response was not accompanied by an increased expression of genes known to be associated with age-associated microglia priming. The increased inflammatory response in microglia correlates closely with increased peripheral inflammation, a loss of blood-brain barrier integrity, and infiltration of immune cells in the brain parenchyma in this mouse model of telomere shortening.
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http://dx.doi.org/10.1111/acel.12370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4693462PMC
December 2015

Histone Deacetylase Inhibition and IκB Kinase/Nuclear Factor-κB Blockade Ameliorate Microvascular Proinflammatory Responses Associated With Hemorrhagic Shock/Resuscitation in Mice.

Crit Care Med 2015 Dec;43(12):e567-80

1Medical Biology Section, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. 2Department of Critical Care, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. 3Department of Anesthesiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Objective: To investigate the consequences of histone deacetylase inhibition by histone deacetylase inhibitor valproic acid and IκB kinase/nuclear factor-κB signaling blockade by IκB kinase inhibitor BAY11-7082 on (microvascular) endothelial cell behavior in vitro as well as in mice subjected to hemorrhagic shock/resuscitation in vivo.

Design: Prospective, randomized laboratory investigation using an established mouse model of hemorrhagic shock.

Setting: Research laboratory at university teaching hospital.

Subjects: Endothelial cells and C57BL/6 male mice.

Interventions: Endothelial cells were incubated with tumor necrosis factor-α in the absence or presence of valproic acid or BAY11-7082 in vitro. Mice were subjected to hemorrhagic shock by blood withdrawn until the mean arterial pressure of 30 mm Hg and maintained at this pressure for 90 minutes. At 90 minutes, subgroups of mice were resuscitated with 4% human albumin in the absence or presence of vehicle, valproic acid (300 μg/g body weight) or BAY11-7082 (400 μg per mouse). Mice were killed 1 hour and 4 hours after resuscitation.

Measurements And Main Results: Valproic acid and BAY11-7082 selectively diminished tumor necrosis factor-α-induced endothelial proinflammatory activation in vitro. In vivo, both systemic and local inflammatory responses were significantly induced by hemorrhagic shock/resuscitation. The decreased histone acetylation in kidneys after hemorrhagic shock/resuscitation was restored by valproic acid treatment. In glomerular endothelial cells, the nuclear translocation of nuclear factor-κB, which was induced by hemorrhagic shock/resuscitation, was eliminated by BAY11-7082 treatment while enhanced in the presence of valproic acid. Both valproic acid and BAY11-7082 significantly attenuated the hemorrhagic shock/resuscitation-induced protein expression of endothelial cell adhesion molecules E-selectin and vascular cell adhesion molecule-1 in the microvasculature of kidneys and liver, although messenger RNA expression levels of these molecules analyzed in whole-organ lysates of kidneys, lungs, and liver were not extensively affected. The reduced protein expression of adhesion molecules was paralleled by diminishing the adhesion/transmigration of neutrophils in kidneys and liver after hemorrhagic shock/resuscitation.

Conclusion: Suppression of histone deacetylase activity and blockade of IκB kinase/nuclear factor-κB signaling during resuscitation ameliorate microvascular endothelial proinflammatory responses in organs in mice after hemorrhagic shock.
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http://dx.doi.org/10.1097/CCM.0000000000001203DOI Listing
December 2015