Prenatal Fluoxetine Exposure Influences Glucocorticoid Receptor-Mediated Activity in the Prefrontal Cortex of Adolescent Rats Exposed to Acute Stress.

Any deviation from the programmed processes of brain development may modify its formation and functions, thereby precipitating pathological conditions, which often become manifest in adulthood. Exposure to a challenge during crucial periods of vulnerability, such as adolescence, may reveal molecular changes preceding behavioral outcomes. Based on a previous study showing that prenatal fluoxetine (FLX) leads to the development of an anhedonic-like behavior in adult rats, we aimed to assess whether the same treatment regimen (i.e., fluoxetine during gestation; 15 mg/kg/day) influences the ability to respond to acute restraint stress (ARS) during adolescence. We subjected the rats to a battery of behavioral tests evaluating the development of various phenotypes (cognitive deficit, anhedonia, and anxiety). Furthermore, we carried out molecular analyses in the plasma and prefrontal cortex, a brain region involved in stress response, and whose functions are commonly altered in neuropsychiatric conditions. Our findings confirm that prenatal manipulation did not affect behavior in adolescent rats but impaired the capability to respond properly to ARS. Indeed, we observed changes in several molecular key players of the hypothalamic pituitary adrenal axis, particularly influencing genomic effects mediated by the glucocorticoid receptor. This study highlights that prenatal FLX exposure influences the ability of adolescent male rats to respond to an acute challenge, thereby altering the functionality of the hypothalamic-pituitary-adrenal axis, and indicates that the prenatal manipulation may prime the response to challenging events during this critical period of life.

Perinatal serotonergic manipulation shapes anhedonic and cognitive behaviors in a sex- and age-dependent manner: Identification of related biological functions at central and peripheral level.

Poor knowledge about psychiatric disorders often results in similar diagnoses for patients with different symptoms, thus limiting the effectiveness of the available medications. As suggested by several lines of evidence, to improve these shortcomings, it is essential to identify biomarkers associated with specific symptoms and to stratify patients into more homogeneous populations taking a further step toward personalized medicine. Here, we aimed to associate specific behavioral phenotypes with specific molecular alterations by employing an animal model based on the pharmacological manipulation of the serotonergic system, which mimics a condition of vulnerability to develop psychiatric disorders. In particular, we treated female and male rats with fluoxetine (FLX 15 mg/kg dissolved in drinking water) during prenatal or early postnatal life, and we evaluated different pathological-like phenotypes (cognitive deficit, anhedonia, and anxiety) by exposing the rats to a battery of behavioral tests during adolescence and adulthood. In addition, we carried out molecular analyses on specific brain areas and in the blood. Our results showed that perinatal FLX administration determined age- and sex-dependent effects, with males being more sensitive to prenatal manipulation and manifesting anhedonic-like behavior and females to early postnatal exposure, exhibiting cognitive deficits and a less anxious phenotype. Furthermore, we identified, peripherally and centrally, biological functions altered by perinatal serotonin modulation regardless of the timing of exposure and sex, and other pathways specific for the pathological-like phenotypes. The results presented here provide new insights into potential biomarkers associated with specific behavioral phenotypes that may be useful for broadening knowledge about psychiatric conditions.

Venlafaxine's effect on resilience to stress is associated with a shift in the balance between glucose and fatty acid utilization.

Brain metabolism is a fundamental process involved in the proper development of the central nervous system and in the maintenance of the main higher functions in humans. As consequence, energy metabolism imbalance has been commonly associated to several mental disorders, including depression. Here, by employing a metabolomic approach, we aimed to establish if differences in energy metabolite concentration may underlie the vulnerability and resilience in an animal model of mood disorder named chronic mild stress (CMS) paradigm. In addition, we have investigated the possibility that modulation of metabolite concentration may represent a pharmacological target for depression by testing whether repeated treatment with the antidepressant venlafaxine may normalize the pathological phenotype by acting at metabolic level. The analyses were conducted in the ventral hippocampus (vHip) for its key role in the modulation of anhedonia, a core symptom of patients affected by depression. Interestingly, we showed that a shift from glycolysis to beta oxidation seems to be responsible for the vulnerability to chronic stress and that vHip metabolism contributes to the ability of the antidepressant venlafaxine to normalize the pathological phenotype, as shown by the reversal of the changes observed in specific metabolites. These findings may provide novel perspectives on metabolic changes that could serve as diagnostic markers and preventive strategies for the early detection and treatment of depression as well as for the identification of potential drug targets.

Chronic N-Acetyl-Cysteine Treatment Enhances the Expression of the Immediate Early Gene Nr4a1 in Response to an Acute Challenge in Male Rats: Comparison with the Antidepressant Venlafaxine.

Despite several antidepressant treatments being available in clinics, they are not effective in all patients. In recent years, N-acetylcysteine (NAC) has been explored as adjunctive therapy for many psychiatric disorders, including depression, for its antioxidant properties. Given the promising efficacy of this compound for the treatment of such pathologies, it is fundamental to investigate, at the preclinical level, the ability of the drug to act in the modulation of neuroplastic mechanisms in basal conditions and during challenging events in order to highlight the potential features of the drug useful for clinical efficacy. To this aim, adult male Wistar rats were treated with the antidepressant venlafaxine (VLX) (10 mg/kg) or NAC (300 mg/kg) for 21 days and then subjected to 1 h of acute restraint stress (ARS). We found that NAC enhanced the expression of several immediate early genes, markers of neuronal plasticity in the ventral and dorsal hippocampus, prefrontal cortex and amygdala, and in particular it mediated the acute-stress-induced upregulation of Nr4a1 expression more than VLX. These data suggested the ability of NAC to induce coping strategies to face external challenges, highlighting its potential for the improvement of neuroplastic mechanisms for the promotion of resilience, in particular via the modulation of Nr4a1.

Resilience to chronic mild stress-induced anhedonia preserves the ability of the ventral hippocampus to respond to an acute challenge.

Stress is a major precipitating factor for psychiatric disorders and its effects may depend on its duration and intensity. Of note, there are differences in individual susceptibility to stress, with some subjects displaying vulnerability and others showing resistance. Furthermore, the ability to react to stressful-life events can alter the response to a subsequent new stressor. Hence, we investigated whether the vulnerability and resilience to the chronic mild stress (CMS) paradigm, in terms of the hedonic phenotype, are paralleled by a different response when facing a novel acute challenge. Specifically, rats submitted to CMS were stratified based on their sucrose intake into vulnerable (anhedonic rats showing reduce intake of sucrose) and resilient (rats not showing the anhedonic-like behavior) subgroups and then further exposed to an acute restraint stress (ARS). Then, neuronal activation was investigated by measuring the gene expression of early immediate (IEG) genes such as Arc and Cfos and early response (ERG) genes, such as Gadd45ß, Sgk1, Dusp1, and Nr4a1, in brain regions that play a crucial role in the stress response. We found that resilient rats preserve the ability to increase ERG expression following the ARS selectively in the ventral hippocampus. Conversely, such ability is lost in vulnerable rats. Interestingly, the recovery from the anhedonic phenotype observed in vulnerable rats after 3 weeks of rest from the CMS procedure also parallels the restoration of the ability to adequately respond to the challenge. In conclusion, these findings support the role of the ventral subregion of the hippocampus in the management of both chronic and acute stress response and point to this brain subregion as a critical target for a potential therapeutic strategy aimed at promoting stress resilience.

Alterations of mitochondrial dynamics in serotonin transporter knockout rats: A possible role in the fear extinction recall mechanisms.

Stress-related mental disorders encompass a plethora of pathologies that share the exposure to a negative environment as trigger for their development. The vulnerability to the effects of a negative environment is not equal to all but differs between individuals based on the genetic background makeup. Here, to study the molecular mechanisms potentially underlying increased threat anticipation, we employed an animal model showing this symptom (5-HTT knockout rats) which we exposed to Pavlovian fear conditioning (FC). We investigated the role of mitochondria, taking advantage of the recent evidence showing that the dynamic of these organelles is dysregulated after stress exposure. Behavioral experiments revealed that, during the second day of extinction of the FC paradigm, 5-HTT knockout (5-HTT-/-) animals showed a lack of fear extinction recall. From a mechanistic standpoint, we carried out our molecular analyses on the amygdala and prefrontal cortex, given their role in the management of the fear response due to their tight connection. We demonstrated that mitochondrial dynamics are impaired in the amygdala and prefrontal cortex of 5-HTT-/- rats. The dissection of the potential contributing factors revealed a critical role in the mechanisms regulating fission and fusion that are dysregulated in transgenic animals. Furthermore, mitochondrial oxidative phosphorylation, mitochondrial biogenesis, and the production of antioxidant enzymes were altered in these brain regions in 5-HTT-/- rats. In summary, our data suggest that increased extracellular 5-HT levels cause an unbalance of mitochondrial functionality that could contribute to the reduced extinction recall of 5-HTT-/- rats, pointing out the role of mitochondrial dynamics in the etiology of psychiatric disorders. Our findings, also, provide some interesting insights into the targeted development of drugs to treat such disorders.

Metabolomic signature and mitochondrial dynamics outline the difference between vulnerability and resilience to chronic stress.

Stress is the foremost environmental factor involved in the pathophysiology of major depressive disorder (MDD). However, individual differences among people are critical as some people exhibit vulnerability while other are resilient to repeated exposure to stress. Among the others, a recent theory postulates that alterations of energy metabolism might contribute to the development of psychopathologies. Here we show that the bioenergetic status in the ventral hippocampus (vHip), a brain subregion tightly involved in the regulation of MDD, defined the development of vulnerability or resilience following two weeks of chronic mild stress. Among the different metabolomic signatures observed, the glycolysis and tricarboxylic acid cycle may be specifically involved in defining vulnerability, revealing a previously unappreciated mechanism of sensitivity to stress. These findings point to mitochondrial morphology and recycling as critical in the ability to cope with stress. We show that vulnerable rats favor mitochondrial fusion to counteract the overproduction of reactive oxidative species whereas resilient rats activate fission to guarantee metabolic efficiency. Our results indicate that the modulation of the energetic metabolite profile in vHip under chronic stress exposure may represent a mechanism to explain the difference between vulnerable and resilient rats, unraveling novel and promising targets for specific therapeutic interventions.

The coupling of RACK1 with the beta isoform of the glucocorticoid receptor promotes resilience to chronic stress exposure.

Several intracellular pathways that contribute to the adaptation or maladaptation to environmental challenges mediate the vulnerability and resilience to chronic stress. The activity of the hypothalamic-pituitary-adrenal (HPA) axis is fundamental for the proper maintenance of brain processes, and it is related to the functionality of the isoform alfa and beta of the glucocorticoid receptor (Gr), the primary regulator of HPA axis. Among the downstream effectors of the axis, the scaffolding protein RACK1 covers an important role in regulating synaptic activity and mediates the transcription of the neurotrophin Bdnf. Hence, by employing the chronic mild stress (CMS) paradigm, we studied the role of the Grß-RACK1-Bdnf signaling in the different susceptibility to chronic stress exposure. We found that resilience to two weeks of CMS is paralleled by the activation of this pathway in the ventral hippocampus, the hippocampal subregion involved in the modulation of stress response. Moreover, the results we obtained in vitro by exposing SH-SY5Y cells to cortisol support the data we found in vivo. The results obtained add novel critical information about the link among Gr, RACK1 and Bdnf and the resilience to chronic stress, suggesting novel targets for the treatment of stress-related disorders, including depression.

Microbial biofilm correlates with an increased antibiotic tolerance and poor therapeutic outcome in infective endocarditis.

BACKGROUND: Infective endocarditis (IE) is associated with high rates of mortality. Prolonged treatments with high-dose intravenous antibiotics often fail to eradicate the infection, frequently leading to high-risk surgical intervention. By providing a mechanism of antibiotic tolerance, which escapes conventional antibiotic susceptibility profiling, microbial biofilm represents a key diagnostic and therapeutic challenge for clinicians. This study aims at assessing a rapid biofilm identification assay and a targeted antimicrobial susceptibility profile of biofilm-growing bacteria in patients with IE, which were unresponsive to antibiotic therapy. RESULTS: Staphylococcus aureus was the most common isolate (50%), followed by Enterococcus faecalis (25%) and Streptococcus gallolyticus (25%). All microbial isolates were found to be capable of producing large, structured biofilms in vitro. As expected, antibiotic treatment either administered on the basis of antibiogram or chosen empirically among those considered first-line antibiotics for IE, including ceftriaxone, daptomycin, tigecycline and vancomycin, was not effective at eradicating biofilm-growing bacteria. Conversely, antimicrobial susceptibility profile of biofilm-growing bacteria indicated that teicoplanin, oxacillin and fusidic acid were most effective against S. aureus biofilm, while ampicillin was the most active against S. gallolyticus and E. faecalis biofilm, respectively. CONCLUSIONS: This study indicates that biofilm-producing bacteria, from surgically treated IE, display a high tolerance to antibiotics, which is undetected by conventional antibiograms. The rapid identification and antimicrobial tolerance profiling of biofilm-growing bacteria in IE can provide key information for both antimicrobial therapy and prevention strategies.

Association between CMV and Invasive Fungal Infections After Autologous Stem Cell Transplant in Lymphoproliferative Malignancies: Opportunistic Partnership or Cause-Effect Relationship?

Unlike allogeneic transplant, autologous stem cell transplantation (ASCT) represents a procedure with a low-risk of cytomegalovirus (CMV) symptomatic reactivation-infection/end-organ disease (CMV complications) and invasive fungal disease (IFD). However, novel drugs for the treatment of lymphoproliferative malignancies could cause an increase of such opportunistic infections, even after ASCT. To the best of our knowledge, there are no published data demonstrating an association between CMV and IFD in the autologous setting, while this association has been widely reported in allogeneic transplantation. We have reviewed our series of 347 ASCT in myeloma and lymphoma patients performed over a period of 14 years with the aim of investigating the descriptive and analytical epidemiology of bacterial, CMV and IFD complications, focusing on the association between CMV and IFD. Patients with myeloma have significantly fewer bacterial infections and IFD than patients with lymphoma, but a similar rate of CMV complications. Descriptive epidemiological data are consistent with the literature, indicating an overall incidence of 36%, 3.5% and 15.5% for bacterial infections, IFD and CMV complications, with a case mortality rate of 4%, 16.7% and 3.7%, respectively. A strong correlation between CMV and IFD exists, with 8 cases of IFD out of a total of 12 presenting a CMV complication. At multivariate analysis, a diagnosis of lymphoma, ≥3 previous treatment lines and age ≥60 years were found to be independent risk factors for IFD. Duration of neutropenia (ANC < 500/mm³) ≥7 days represents an independent risk factor for CMV complications, where neutropenia most likely represents a crude surrogate biomarker indicating a deeper and longer state of overall immunosuppression. From our data we conclude that (1) myeloma patients are at lower risk of bacterial infections and IFD as compared with lymphoma patients but are at equal risk of CMV complications, most likely as a consequence of a selective impact of bortezomib on Herpes Viruses infection control; (2) a significant association exists between CMV and IFD, although a possible cause-effect relationship remains to be determined; (3) IFD is a rare complication after ASCT but burdened by a mortality rate of about 17%, with peak rates in older lymphoma patients who underwent more intensive therapeutic regimens.

The Emerging Role of Microbial Biofilm in Lyme Neuroborreliosis.

Lyme borreliosis (LB) is the most common tick-borne disease caused by the spirochete Borrelia burgdorferi in North America and Borrelia afzelii or Borrelia garinii in Europe and Asia, respectively. The infection affects multiple organ systems, including the skin, joints, and the nervous system. Lyme neuroborreliosis (LNB) is the most dangerous manifestation of Lyme disease, occurring in 10-15% of infected individuals. During the course of the infection, bacteria migrate through the host tissues altering the coagulation and fibrinolysis pathways and the immune response, reaching the central nervous system (CNS) within 2 weeks after the bite of an infected tick. The early treatment with oral antimicrobials is effective in the majority of patients with LNB. Nevertheless, persistent forms of LNB are relatively common, despite targeted antibiotic therapy. It has been observed that the antibiotic resistance and the reoccurrence of Lyme disease are associated with biofilm-like aggregates in B. burgdorferi, B. afzelii, and B. garinii, both in vitro and in vivo, allowing Borrelia spp. to resist to adverse environmental conditions. Indeed, the increased tolerance to antibiotics described in the persisting forms of Borrelia spp., is strongly reminiscent of biofilm growing bacteria, suggesting a possible role of biofilm aggregates in the development of the different manifestations of Lyme disease including LNB.

The clinical Biofilm Ring Test: a promising tool for the clinical assessment of biofilm-producing Candida species.

Candida species are opportunistic pathogens responsible for a variety of diseases, ranging from skin and mucosal lesions to severe systemic, life-threatening infections. Candida albicans accounts for more than 70% of all Candida infections, however, the clinical relevance of other species such as Candida parapsilosis and Candida krusei are being increasingly recognized. Biofilm-producing yeasts cells acquire an increased resistance to antifungal agents, often leading to therapeutic failure and chronic infection. Conventional methods such as crystal violet (CV) and tetrazolium (XTT) reduction assay, developed to evaluate biofilm formation in Candida species are usually time-consuming, present a high intra- and inter-assay variability of the results and are therefore hardly applicable to routine diagnostics. This study describes an in-vitro assay developed for the measurement of biofilm formation in Candida species based on the clinical Biofilm Ring Test® (cBRT). We found a significant concordance between the cBRT and both CV (k = 0.74) and XTT (k = 0.62), respectively. Nevertheless, the cBRT resulted more reliable and reproducible than CV and XTT, requiring a minimal sample manipulation and allowing a high throughput assessment, directly on viable cells. The results indicate that the cBRT may provide a suitable, cost-effective technique for routine biofilm testing in clinical microbiology.

Biofilm is a Major Virulence Determinant in Bacterial Colonization of Chronic Skin Ulcers Independently from the Multidrug Resistant Phenotype.

Bacterial biofilm is a major factor in delayed wound healing and high levels of biofilm production have been repeatedly described in multidrug resistant organisms (MDROs). Nevertheless, a quantitative correlation between biofilm production and the profile of antimicrobial drug resistance in delayed wound healing remains to be determined. Microbial identification, antibiotic susceptibility and biofilm production were assessed in 135 clinical isolates from 87 patients. Gram-negative bacteria were the most represented microorganisms (60.8%) with MDROs accounting for 31.8% of the total isolates. Assessment of biofilm production revealed that 80% of the strains were able to form biofilm. A comparable level of biofilm production was found with both MDRO and not-MDRO with no significant differences between groups. All the methicillin-resistant Staphylococcus aureus (MRSA) and 80% of Pseudomonas aeruginosa MDR strains were found as moderate/high biofilm producers. Conversely, less than 17% of Klebsiella pneumoniae extended-spectrum beta-lactamase (ESBL), Escherichia coli-ESBL and Acinetobacter baumannii were moderate/high biofilm producers. Notably, those strains classified as non-biofilm producers, were always associated with biofilm producer bacteria in polymicrobial colonization. This study shows that biofilm producers were present in all chronic skin ulcers, suggesting that biofilm represents a key virulence determinant in promoting bacterial persistence and chronicity of ulcerative lesions independently from the MDRO phenotype.

Campylobacter jejuni Fatal Sepsis in a Patient with Non-Hodgkin's Lymphoma: Case Report and Literature Review of a Difficult Diagnosis.

Campylobacter jejuni (C. jejuni) bacteremia is difficult to diagnose in individuals with hematological disorders undergoing chemotherapy. The cause can be attributed to the rarity of this infection, to the variable clinical presentation, and to the partial overlapping symptoms underlying the disease. Here, we report a case of a fatal sepsis caused by C. jejuni in a 76-year-old Caucasian man with non-Hodgkin's lymphoma. After chemotherapeutic treatment, the patient experienced fever associated with severe neutropenia and thrombocytopenia without hemodynamic instability, abdominal pain, and diarrhea. The slow growth of C. jejuni in the blood culture systems and the difficulty in identifying it with conventional biochemical phenotyping methods contributed to the delay of administering a targeted antimicrobial treatment, leading to a fatal outcome. Early recognition and timely intervention are critical for the successful management of C. jejuni infection. Symptoms may be difficult to recognize in immunocompromised patients undergoing chemotherapy. Thus, it is important to increase physician awareness regarding the clinical manifestations of C. jejuni to improve therapeutic efficacy. Moreover, the use of more aggressive empirical antimicrobial treatments with aminoglycosides and/or carbapenems should be considered in immunosuppressed patients, in comparison to those currently indicated in the guidelines for cancer-related infections supporting the use of cephalosporins as monotherapy.

Microbiologic characteristics and predictors of mortality in bloodstream infections in intensive care unit patients: A 1-year, large, prospective surveillance study in 5 Italian hospitals.

BACKGROUND: Bloodstream infections (BSIs) from multidrug-resistant (MDR) bacteria cause morbidity and mortality in intensive care unit (ICU) patients worldwide. This study investigated the incidence of BSIs in 5 adult general ICUs in Rome, Italy, and evaluated the mortality rate and risk factors associated with these infections. METHODS: Over a 12-month period, 1,318 patients were enrolled. Demographic characteristics, Simplified Acute Physiology Score II (SAPS II), comorbidities, and BSI isolate data were collected. After stratification for the outcome, statistical analysis was performed to assess the impact of patient risk factors on in-hospital mortality. RESULTS: There were 324 BSIs in 175 patients recorded, with an in-hospital mortality rate of 46%. Univariate analysis revealed that SAPS II, cardiac comorbidity, and Klebsiella pneumoniae BSI were significantly associated with a higher risk of death. Having a K pneumoniae BSI and cardiac illness at admission were both confirmed to be associated with death by multivariate analysis (P = .0162 and P = .0158, respectively). Most of the K pneumoniae isolates showed high resistance rates to carbapenems. CONCLUSION: BSIs caused by K pneumoniae and cardiovascular comorbidity in ICU patients are associated with a higher risk of death. Thorough surveillance for MDR pathogens and stratification of the patients' risk on admission into the ICU are key to improving the outcomes of these infections.