Evolutionarily conserved amino acids in MHC-II mediate bat influenza A virus entry into human cells.

The viral hemagglutinins of conventional influenza A viruses (IAVs) bind to sialylated glycans on host cell surfaces for attachment and subsequent infection. In contrast, hemagglutinins of bat-derived IAVs target major histocompatibility complex class II (MHC-II) for cell entry. MHC-II proteins from various vertebrate species can facilitate infection with the bat IAV H18N11. Yet, it has been difficult to biochemically determine the H18:MHC-II binding. Here, we followed a different approach and generated MHC-II chimeras from the human leukocyte antigen DR (HLA-DR), which supports H18-mediated entry, and the nonclassical MHC-II molecule HLA-DM, which does not. In this context, viral entry was supported only by a chimera containing the HLA-DR α1, α2, and ß1 domains. Subsequent modeling of the H18:HLA-DR interaction identified the α2 domain as central for this interaction. Further mutational analyses revealed highly conserved amino acids within loop 4 (N149) and ß-sheet 6 (V190) of the α2 domain as critical for virus entry. This suggests that conserved residues in the α1, α2, and ß1 domains of MHC-II mediate H18-binding and virus propagation. The conservation of MHC-II amino acids, which are critical for H18N11 binding, may explain the broad species specificity of this virus.

Various mutations in icaR, the repressor of the icaADBC locus, occur in mucoid Staphylococcus aureus isolates recovered from the airways of people with cystic fibrosis.

Staphylococcus aureus is one of the major pathogens isolated from the airways of people with cystic fibrosis (pwCF). Recently, we described a mucoid S. aureus phenotype from respiratory specimens of pwCF, which constitutively overproduced biofilm that consisted of polysaccharide intercellular adhesin (PIA) due to a 5bp-deletion (5bp-del) in the intergenic region of the intercellular adhesin (ica) locus. Since we were not able to identify the 5bp-del in mucoid isolates of two pwCF with long-term S. aureus persistence and in a number of mucoid isolates of pwCF from a prospective multicenter study, these strains were (i) characterized phenotypically, (ii) investigated for biofilm formation, and (iii) molecular typed by spa-sequence typing. To screen for mutations responsible for mucoidy, the ica operon of all mucoid isolates was analyzed by Sanger sequencing. Whole genome sequencing was performed for selected isolates. For all mucoid isolates without the 5 bp-del, various mutations in icaR, which is the transcriptional repressor of the icaADBC operon. Mucoid and non-mucoid strains belonged to the same spa-type. Transformation of PIA-overproducing S. aureus with a vector expressing the intact icaR gene restored the non-mucoid phenotype. Altogether, we demonstrated a new mechanism for the emergence of mucoid S. aureus isolates of pwCF.

Alterations in nicotinic receptor alpha5 subunit gene differentially impact early and later stages of cocaine addiction: a translational study in transgenic rats and patients.

Cocaine addiction is a chronic and relapsing disorder with an important genetic component. Human candidate gene association studies showed that the single nucleotide polymorphism (SNP) rs16969968 in the α5 subunit (α5SNP) of nicotinic acetylcholine receptors (nAChRs), previously associated with increased tobacco dependence, was linked to a lower prevalence of cocaine use disorder (CUD). Three additional SNPs in the α5 subunit, previously shown to modify α5 mRNA levels, were also associated with CUD, suggesting an important role of the subunit in this pathology. To investigate the link between this subunit and CUD, we submitted rats knockout for the α5 subunit gene (α5KO), or carrying the α5SNP, to cocaine self-administration (SA) and showed that the acquisition of cocaine-SA was impaired in α5SNP rats while α5KO rats exhibited enhanced cocaine-induced relapse associated with altered neuronal activity in the nucleus accumbens. In addition, we observed in a human cohort of patients with CUD that the α5SNP was associated with a slower transition from first cocaine use to CUD. We also identified a novel SNP in the ß4 nAChR subunit, part of the same gene cluster in the human genome and potentially altering CHRNA5 expression, associated with shorter time to relapse to cocaine use in patients. In conclusion, the α5SNP is protective against CUD by influencing early stages of cocaine exposure while CHRNA5 expression levels may represent a biomarker for the risk to relapse to cocaine use. Drugs modulating α5 containing nAChR activity may thus represent a novel therapeutic strategy against CUD.

Activation of cGAS/STING pathway upon paramyxovirus infection.

During inflammatory diseases, cancer, and infection, the cGAS/STING pathway is known to recognize foreign or self-DNA in the cytosol and activate an innate immune response. Here, we report that negative-strand RNA paramyxoviruses, Nipah virus (NiV), and measles virus (MeV), can also trigger the cGAS/STING axis. Although mice deficient for MyD88, TRIF, and MAVS still moderately control NiV infection when compared with wild-type mice, additional STING deficiency resulted in 100% lethality, suggesting synergistic roles of these pathways in host protection. Moreover, deletion of cGAS or STING resulted in decreased type I interferon production with enhanced paramyxoviral infection in both human and murine cells. Finally, the phosphorylation and ubiquitination of STING, observed during viral infections, confirmed the activation of cGAS/STING pathway by NiV and MeV. Our data suggest that cGAS/STING activation is critical in controlling paramyxovirus infection and possibly represents attractive targets to develop countermeasures against severe disease induced by these pathogens.

BET bromodomain-containing epigenetic reader proteins regulate vascular smooth muscle cell proliferation and neointima formation.

AIMS: Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo. METHODS AND RESULTS: Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice. CONCLUSION: Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.

The novel mineralocorticoid receptor antagonist finerenone attenuates neointima formation after vascular injury.

BACKGROUND: The novel nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone holds promise to be safe and efficient in the treatment of patients with heart failure and/or chronic kidney disease. However, its effects on vascular function remain elusive. PURPOSE: The aim of this study was to determine the functional effect of selective MR antagonism by finerenone in vascular cells in vitro and the effect on vascular remodeling following acute vascular injury in vivo. METHODS AND RESULTS: In vitro, finerenone dose-dependently reduced aldosterone-induced smooth muscle cell (SMC) proliferation, as quantified by BrdU incorporation, and prevented aldosterone-induced endothelial cell (EC) apoptosis, as measured with a flow cytometry based caspase 3/7 activity assay. In vivo, oral application of finerenone resulted in an accelerated re-endothelialization 3 days following electric injury of the murine carotid artery. Furthermore, finerenone treatment inhibited intimal and medial cell proliferation following wire-induced injury of the murine femoral artery 10 days following injury and attenuated neointimal lesion formation 21 days following injury. CONCLUSION: Finerenone significantly reduces apoptosis of ECs and simultaneously attenuates SMC proliferation, resulting in accelerated endothelial healing and reduced neointima formation of the injured vessels. Thus, finerenone appears to provide favorable vascular effects through restoring vascular integrity and preventing adverse vascular remodeling.

A brief office intervention is associated with increased days per week of exercise.

OBJECTIVE: We hypothesized that a cardiologist-initiated motivational discussion during a routine general cardiology clinic visit that included an exercise 'contract' signed by the patient, physician and a witness, would increase self-reported days per week of exercise. METHODS: A short-term pilot intervention was provided to forty consecutive general cardiology clinic patients who were enrolled in 2005. They were asked to answer the question "How many days each week do you exercise" prior to the motivational discussion and at routine follow-up. Each participant signed an exercise 'contract' and agreed to exercise for at least 15 min everyday. RESULTS: Participants had an average follow-up of 3.2 (1.7) months. The initial visit mean days of exercise per week were 3.1 (1.9). At follow-up, mean days of exercise per week were 4.0 (1.8), (p=0.04). CONCLUSION: This simple rapid intervention was associated with increased self-reported days per week of exercise.