A Study of Cecal Ligation and Puncture-Induced Sepsis in Tissue-Specific Tumor Necrosis Factor Receptor 1-Deficient Mice.

Sepsis is a complex syndrome resulting from a dysregulated immune response to an infection. Due to the high prevalence, morbidity, and mortality, there is a lot of interest in understanding pathways that play a role in sepsis, with a focus on the immune system. Tumor necrosis factor (TNF) is a pleiotropic pro-inflammatory cytokine and a master regulator of the immune system but clinical trials with TNF blockers in sepsis have failed to demonstrate significant protection. Since TNF stimulates two different receptors, TNF receptor 1 (TNFR1) and TNFR2, pan-TNF inhibition might be suboptimal since both receptors have opposite functions in polymicrobial sepsis. Therefore, we hypothesized that TNF has a dual role in sepsis, namely a mediating and a protective role, and that protection might be obtained by TNFR1-specific inhibition. We here confirmed that TNFR1-/- mice are protected in the sterile endotoxemia model, whereas TNFR1 deficiency did not protect in the cecal ligation and puncture (CLP)-induced polymicrobial sepsis model. Since whole body TNFR1 blockage might be deleterious because of the antibacterial function of TNF/TNFR1 signaling, we focused on the potential devastating role of TNF/TNFR1 signaling in specific cell types. We were interested in the gut epithelium, the endothelium, and hepatocytes using conditional TNFR1-/- mice, as these cell types have been shown to play a role in sepsis. However, none of these conditional knockout mice showed improved survival in the CLP model. We conclude that cell-specific targeting of TNFR1 to these cell types has no therapeutic future in septic peritonitis.

A screening assay for Selective Dimerizing Glucocorticoid Receptor Agonists and Modulators (SEDIGRAM) that are effective against acute inflammation.

It has been suggested that glucocorticoid receptor (GR) agonists that promote GR homodimerization more than standard glucocorticoids such as Dexamethasone could be more effective anti-inflammatory molecules against acute and life-threatening inflammatory conditions. To test this hypothesis, we set up a screening pipeline aimed at discovering such Selective Dimerizing GR Agonists and Modulators (SEDIGRAM). The pipeline consists of a reporter gene assay based on a palindromic glucocorticoid responsive element (GRE). This assay represents GR dimerization in human A549 lung epithelial cells. In the pipeline, this is followed by analysis of endogenous GRE-driven gene expression, a FRET assay confirming dimerization, and monitoring of in vitro and in vivo anti-inflammatory activity. In a proof of principle experiment, starting from seven candidate compounds, we identified two potentially interesting compounds (Cortivazol and AZD2906) that confer strong protection in a mouse model of aggressive TNF-induced lethal inflammation. A screening pipeline for SEDIGRAM may assist the search for compounds that promote GR dimerization and limit overwhelming acute inflammatory responses.

Simultaneous Inhibition of Tumor Necrosis Factor Receptor 1 and Matrix Metalloproteinase 8 Completely Protects Against Acute Inflammation and Sepsis.

OBJECTIVES: Sepsis causes very high mortality and morbidity rates and remains one of the biggest medical challenges. This study investigates whether plasma levels of both matrix metalloproteinase 8 and tumor necrosis factor receptor 1 are associated with sepsis severity and also investigates the therapeutic applicability of simultaneous inhibition of the two molecules in sepsis. DESIGN: Observational human pilot study-prospective controlled animal study. SETTING: University hospital and research laboratory. SUBJECTS: Sepsis patients and C57BL/6 mice deficient for matrix metalloproteinase 8 and/or tumor necrosis factor receptor 1. INTERVENTION: Plasma and whole blood RNA were collected from 13 sepsis patients for 7 consecutive days and within 24 hours of admission to ICU. Matrix metalloproteinase 8 and tumor necrosis factor receptor 1 plasma and expression levels were determined in these patients. Mice deficient for both matrix metalloproteinase 8 and tumor necrosis factor receptor 1 were generated and subjected to endotoxemia and cecal ligation and puncture. Additionally, a bispecific Nanobody that simultaneously blocks matrix metalloproteinase 8 and tumor necrosis factor receptor 1 was created. MEASUREMENTS AND MAIN RESULTS: Plasma levels of matrix metalloproteinase 8 and tumor necrosis factor receptor 1 were positively correlated with the Sequential Organ Failure Assessment score (r, 0.51 and 0.58) and interleukin 6 levels (r, 0.59 and 0.52) in 13 sepsis patients. Combined elimination of tumor necrosis factor receptor 1 and matrix metalloproteinase 8 in double knockout mice resulted in superior survival in endotoxemia and CLP compared with single knockouts and wild-type mice. Cotreatment with our bispecific Nanobody in CLP resulted in improved survival rates (28% vs 19%) compared with untreated mice. CONCLUSIONS: Inhibition of matrix metalloproteinase 8 and tumor necrosis factor receptor 1 might have therapeutic potential to treat sepsis and proof-of-principle was provided as therapeutics that inhibit both tumor necrosis factor receptor 1 and matrix metalloproteinase 8 are effective in CLP.

TNFR1 inhibition with a Nanobody protects against EAE development in mice.

TNF has as detrimental role in multiple sclerosis (MS), however, anti-TNF medication is not working. Selective TNF/TNFR1 inhibition whilst sparing TNFR2 signaling reduces the pro-inflammatory effects of TNF but preserves the important neuroprotective signals via TNFR2. We previously reported the generation of a Nanobody-based selective inhibitor of human TNFR1, TROS that will be tested in experimental autoimmune encephalomyelitis (EAE). We specifically antagonized TNF/TNFR1 signaling using TROS in a murine model of MS, namely MOG35-55-induced EAE. Because TROS does not cross-react with mouse TNFR1, we generated mice expressing human TNFR1 in a mouse TNFR1-knockout background (hTNFR1 Tg), and we determined biodistribution of 99mTc-TROS and effectiveness of TROS in EAE in those mice. Biodistribution analysis demonstrated that intraperitoneally injected TROS is retained more in organs of hTNFR1 Tg mice compared to wild type mice. TROS was also detected in the cerebrospinal fluid (CSF) of hTNFR1 Tg mice. Prophylactic TROS administration significantly delayed disease onset and ameliorated its symptoms. Moreover, treatment initiated early after disease onset prevented further disease development. TROS reduced spinal cord inflammation and neuroinflammation, and preserved myelin and neurons. Collectively, our data illustrate that TNFR1 is a promising therapeutic target in MS.

Efficient analysis of mouse genome sequences reveal many nonsense variants.

Genetic polymorphisms in coding genes play an important role when using mouse inbred strains as research models. They have been shown to influence research results, explain phenotypical differences between inbred strains, and increase the amount of interesting gene variants present in the many available inbred lines. SPRET/Ei is an inbred strain derived from Mus spretus that has ∼1% sequence difference with the C57BL/6J reference genome. We obtained a listing of all SNPs and insertions/deletions (indels) present in SPRET/Ei from the Mouse Genomes Project (Wellcome Trust Sanger Institute) and processed these data to obtain an overview of all transcripts having nonsynonymous coding sequence variants. We identified 8,883 unique variants affecting 10,096 different transcripts from 6,328 protein-coding genes, which is about 28% of all coding genes. Because only a subset of these variants results in drastic changes in proteins, we focused on variations that are nonsense mutations that ultimately resulted in a gain of a stop codon. These genes were identified by in silico changing the C57BL/6J coding sequences to the SPRET/Ei sequences, converting them to amino acid (AA) sequences, and comparing the AA sequences. All variants and transcripts affected were also stored in a database, which can be browsed using a SPRET/Ei M. spretus variants web tool (www.spretus.org), including a manual. We validated the tool by demonstrating the loss of function of three proteins predicted to be severely truncated, namely Fas, IRAK2, and IFNγR1.

Topical imiquimod yields systemic effects due to unintended oral uptake.

Repetitive application of topical imiquimod is used as an experimental model for the induction of psoriasiform skin lesions in mice. The model is characterized by several inflammatory processes, including cytokine production both locally and systemically, cellular infiltration, and splenomegaly. To investigate the production of type I interferons in response to imiquimod-containing Aldara cream, IFNß-luciferase reporter mice were imaged in vivo and ex vivo. Type I interferons were found to be produced in the skin, but also in the intestinal system caused by unintended ingestion of imiquimod by the mice. Through the use of Elizabethan collars to prevent ingestion, these effects, including psoriasiform lesions were nearly completely prevented. Our findings reveal that topical treatment with Aldara induces a psoriasiform skin inflammation, but that its mode of action depends on ingestion of the chemical, which leads to systemic responses and affects local inflammation. Therefore, potential ingestion of topical treatments during experimental procedures should be taken into account during assessment of cutaneous inflammatory parameters in skin disease models.

Glucocorticoid-induced microRNA-511 protects against TNF by down-regulating TNFR1.

TNF is a central actor during inflammation and a well-recognized drug target for inflammatory diseases. We found that the mouse strain SPRET/Ei, known for extreme and dominant resistance against TNF-induced shock, displays weak expression of TNF receptor 1 protein (TNFR1) but normal mRNA expression, a trait genetically linked to the major TNFR1 coding gene Tnfrsf1a and to a locus harbouring the predicted TNFR1-regulating miR-511. This miRNA is a genuine TNFR1 regulator in cells. In mice, overexpression of miR-511 down-regulates TNFR1 and protects against TNF, while anti-miR-511 up-regulates TNFR1 and sensitizes for TNF, breaking the resistance of SPRET/Ei. We found that miR-511 inhibits endotoxemia and experimental hepatitis and that this miR is strongly induced by glucocorticoids and is a true TNFR1 modulator and thus an anti-inflammatory miR. Since minimal reductions of TNFR1 have considerable effects on TNF sensitivity, we believe that at least part of the anti-inflammatory effects of glucocorti-coids are mediated by induction of this miR, resulting in reduced TNFR1 expression.