Alterations of BDNF, mGluR5, Homer1a, p11 and excitatory/inhibitory balance in corticolimbic brain regions of suicide decedents.

BACKGROUND: Developing biological based approaches for preventing suicide has become a priority. In recent years, there has been a surge in studies investigating the role of the glutamatergic system in suicide, although it remains unclear. METHODS: We evaluated changes in the gene expression of the metabotropic glutamate receptor 5 (mGluR5) and its scaffolding proteins Homer1a and p11 in the dorsolateral prefrontal cortex (DLPFC), amygdala (AMY), and hippocampus (HIP) of 28 suicide decedents (S) (with no clinical psychiatric history or treatment with anxiolytics or antidepressants) and 26 controls (C) by real-time PCR (qPCR). Indeed, we measured BDNF gene expression and VGluT1 and VGAT immunoreactivities in the HIP by qPCR and immunohistochemistry, respectively. Cases and controls matched for age (C: 48.6 ± 11.6 years; S: 46.9 ± 14.5 years) and postmortem interval (PMI; C: 20.1 ± 13h; S: 16.9 ± 5h). RESULTS: In DLPFC, S had lower p11 gene expression levels, but no differences were found in mGluR5 or Homer1a. In the AMY and HIP, mGluR5 and Homer1a were increased, p11 and BDNF were reduced. In the HIP, there were less VGAT-ir and more VGluT1-ir. LIMITATIONS: Future studies are necessary to evaluate protein levels, and determine the cell types and potential compensatory mechanisms in a larger sample including S diagnosed with psychiatric disorders, females and different ethnicities. CONCLUSIONS: This study identified significant alterations in mGluR5, Homer1a, p11, BDNF and excitatory/inhibitory balance in corticolimbic brain areas of S. These results further characterize the biological basis of suicide, contributing to the identification of potential biomarkers for suicide prevention.

Tracking the Emergence and Dissemination of a blaNDM-23 Gene in a Multidrug Resistance Plasmid of Klebsiella pneumoniae.

Since the discovery of blaNDM-1, NDM ß-lactamases have become one of the most widespread carbapenemases worldwide. To date, 43 different NDM variants have been reported but some, such as blaNDM-23, have not been characterized in detail yet. Here, we describe the emergence of a novel blaNDM-23 allele from a blaNDM-1 ancestor and the multidrug resistance plasmid that has disseminated it through a Klebsiella pneumoniae ST437 clone in several Spanish hospitals. Between 2016 and 2019, 1,972 isolates were collected in an epidemiological survey for extended-spectrum-ß-lactamase (ESBL)-producing Klebsiella pneumoniae in the Comunitat Valenciana (Spain). Three carbapenem-resistant strains failed to be detected by carbapenemase-producing Enterobacteriaceae (CPE) screening tests. These isolates carried a blaNDM-23 gene. To characterize this gene, its emergence, and its dissemination, we performed antimicrobial susceptibility tests, hybrid sequencing with Illumina and Nanopore technologies, and phylogenetic analyses. The MICs of the blaNDM-23 allele were identical to those of the blaNDM-1 allele. The blaNDM-23 allele was found in 14 isolates on a 97-kb nonmobilizable, multidrug-resistant plasmid carrying 19 resistance genes for 9 different antimicrobial families. In this plasmid, the blaNDM-23 gene is in the variable region of a complex class 1 integron with a singular genetic environment. The small genetic distance between blaNDM-23-producing isolates reflects a 5-year-long clonal dispersion involving several hospitals and interregional spread. We have characterized the genomic and epidemiological contexts in the emergence and community spread of a new blaNDM-23 allele in a multidrug resistance (MDR) plasmid of Klebsiella pneumoniae. IMPORTANCE At a time when antimicrobial resistance has become one of the biggest concerns worldwide, the emergence of novel alleles and extremely drug-resistant plasmids is a threat to public health worldwide, especially when they produce carbapenem resistance in one of the most problematic pathogens, such as Klebsiella pneumoniae. We used genomic epidemiology to describe the emergence of a novel NDM-23 allele and identify it in a MDR plasmid that has disseminated through a K. pneumoniae ST437 clone in several hospitals in Spain. Using bioinformatic and phylogenetic analyses, we have traced the evolutionary and epidemiological route of the new allele, the hosting plasmid, and the strain that carried both of them from Pakistan to Spain. A better understanding of the NDM-producing K. pneumoniae populations and plasmids has made evident the spread of this clone through the region, enhancing the importance of genomic surveillance in the control of antimicrobial resistance.

Alterations in Gene and Protein Expression of Cannabinoid CB2 and GPR55 Receptors in the Dorsolateral Prefrontal Cortex of Suicide Victims.

Recent studies point to the cannabinoid CB2 receptors (CB2r) and the non-cannabinoid receptor GPR55 as potential key targets involved in the response to stress, anxiety, and depression. Considering the close relationship between neuropsychiatric disorders and suicide, the purpose of this study was to evaluate the potential alterations of CB2r and GPR55 in suicide victims. We analyzed gene and protein expression of both receptors by real-time PCR and western blot, respectively, in the dorsolateral prefrontal cortex (DLPFC) of 18 suicide victims with no clinical psychiatric history or treatment with anxiolytics or antidepressants, and 15 corresponding controls. We used in situ proximity ligation assay to evaluate whether the receptors formed heteromeric complexes and to determine the expression level of these heteromers, also assessing the co-expression of heteromers in neurons, astroglia, or microglia cells. CB2r and GPR55 gene expressions were significantly lower (by 33 and 41%, respectively) in the DLPFC of suicide cases. CB2r protein expression was higher, as were CB2-GPR55 heteroreceptor complexes. The results also revealed the presence of CB2-GPR55 receptor heteromers in both neurons and astrocytes, whereas microglial cells showed no expression. We did not observe any significant alterations of GPR55 protein expression. Additional studies will be necessary to evaluate if these alterations are reproducible in suicide victims diagnosed with different psychiatric disorders. Taken together, the results suggest that CB2r and GPR55 may play a relevant role in the neurobiology of suicide.

Abnormal expression pattern of Notch receptors, ligands, and downstream effectors in the dorsolateral prefrontal cortex and amygdala of suicidal victims.

Recent studies have associated alterations of neuronal plasticity in specific brain areas with suicidal behavior. The Notch signaling pathway plays a relevant role in the control of stem cell maintenance, cell migration, and neuronal plasticity. In the present study, the gene expression of the four Notch receptors (NOTCH1-4), the five canonical ligands (DLL1, DLL3, DLL4, JAGGED1, and JAGGED2), the two non-canonical ligands (DLK1 and DLK2), and the transcription factors (HES1, HEY1, and HEY2) were measured in the dorsolateral prefrontal cortex (DLPFC) and amygdala (AMY) of suicide victims (S; n = 13 males, with no clinical psychiatric history and non-treated with anxiolytic or antidepressant drugs) and their corresponding controls (C; n = 13 males) by real-time PCR. The results revealed a reduction of NOTCH2 and NOTCH1, NOTCH3, and NOTCH4 gene expression in the DLPFC and AMY of S compared with C, respectively. DLL1 levels were increased in the DLPFC and decreased in the AMY, whereas DLL4, JAGGED1, and JAGGED2 were significantly decreased in the regions analyzed. DLK1 was reduced in the AMY, whereas no changes were observed in the DLPFC and in DLK2 expression levels in any of the regions analyzed. HES1 was significantly reduced in both brain regions from S, whereas there were no significant changes in HEY1 and HEY2. This study provides evidence suggesting that the Notch signaling pathway could be a potential key target in the treatment of suicidal behaviors.

Gene and protein alterations of FKBP5 and glucocorticoid receptor in the amygdala of suicide victims.

Recent reports suggest that FKBP5 gene and its corresponding FKBP5 protein play a relevant role in the regulation of anxiety and depression in animal models and human stress-related disorders. In the present study, FKBP5 and glucocorticoid receptor (GR) gene and protein expression were analyzed in the amygdala (AMY) of suicide victims (n=13 males, without clinical psychiatric history and non-treated with anxiolytic or antidepressant drugs) and its corresponding controls (n=13 males) by real-time PCR and Western blotting. The results revealed that FKBP5 and GR gene expression were significantly reduced in the AMY (-38% and -48%, respectively) of suicide victims compared with controls. Interestingly, FKBP5 and GR protein expression were also significantly decreased (-41% and -42%, respectively) in the AMY of suicide victims compared with controls. These results suggest that the FKBP5 plays a relevant role in human emotional responses and suggest this receptor as a new promising target in the treatment of suicide behavior.