Mechanistic and functional studies of the interaction of a proline-rich antimicrobial peptide with mammalian cells.

Mammalian antimicrobial peptides provide rapid defense against infection by inactivating pathogens and by influencing the functions of cells involved in defense responses. Although the direct antibacterial properties of these peptides have been widely characterized, their multiple effects on host cells are only beginning to surface. Here we investigated the mechanistic and functional aspects of the interaction of the proline-rich antimicrobial peptide Bac7(1-35) with mammalian cells, as compared with a truncated analog, Bac7(5-35), lacking four critical N-terminal residues (RRIR) of the Bac7(1-35) sequence. By using confocal microscopy and flow cytometry, we showed that although the truncated analog Bac7(5-35) remains on the cell surface, Bac7(1-35) is rapidly taken up into 3T3 and U937 cells through a nontoxic energy- and temperature-dependent process. Cell biology-based assays using selective endocytosis inhibitors and spectroscopic and surface plasmon resonance studies of the interaction of Bac7(1-35) with phosphatidylcholine/cholesterol model membranes collectively suggest the concurrent contribution of macropinocytosis and direct membrane translocation. Structural studies with model membranes indicated that membrane-bound Bac7(5-35) is significantly more aggregated than Bac7(1-35) due to the absence of the N-terminal cationic cluster, thus providing an explanation for hampered cellular internalization of the truncated form. Further investigations aimed to reveal functional implications of intracellular uptake of Bac7(1-35) demonstrated that it correlates with enhanced S phase entry of 3T3 cells, indicating a novel function for this proline-rich peptide

Exploring the biological properties and therapeutic potential of antimicrobial peptides

The researchers involved in the Trans2Care project at the Department of Medical and Biological Sciences of the University of Udine investigate the biological properties of the antimicrobial peptides (AMPs) of the immune system and their therapeutic potential for human and veterinary application. In addition to potent and broad-spectrum antimicrobial activities, some AMPs display anti-inflammatory and immunomodulatory effects and hold promise as novel antiinfective agents combining antibiotic and immunostimulating properties. A detailed knowledge of their physicochemical, biological and pharmacological properties and of their impact on clinical settings is an important prerequisite to this end. The Trans2Care project offers an invaluable opportunity to share knowledge, technical expertise and laboratory facilities to achieve a better understanding of the biological features and therapeutic potential of AMPs

Molecular cloning and chemical synthesis of a novel antibacterial peptide derived from pig myeloid cells

A group of myeloid precursors of defense peptides has recently been shown to have highly homologous N-terminal regions. Using a strategy based on this homology, a novel cDNA was cloned from pig bone marrow RNA and found to encode a 153-residue polypeptide. This comprises a highly conserved region encompassing a 29-residue signal peptide and a 101-residue prosequence, followed by a unique, 23-residue, cationic, C-terminal sequence. A peptide corresponding to this C-terminal sequence was chemically synthesized and shown to exert antimicrobial activity against both Gram positive and negative bacteria at concentrations of 2-16 microM. The activity of this potent and structurally novel antibacterial peptide appears to be mediated by its ability to damage bacterial membranes, as shown by the rapid permeabilization of the inner membrane of Escherichia coli

The cDNA of the neutrophil antibiotic Bac5 predicts a pro-sequence homologous to a cysteine proteinase inhibitor that is common to other neutrophil antibiotics.

Bac5 is a 5-kDa proline- and arginine-rich antibiotic, stored as inactive precursor (proBac5) in the large granules of bovine neutrophils. A full-length cDNA encoding the precursor form of Bac5 has been cloned. The encoded protein (pre-proBac5) has a calculated mass of 20,031 Da and a pI of 9.21. This comprises a putative signal peptide of 29 amino acid residues and a 101-residue pro-sequence that precede the mature antibiotic. The pro-sequence is acidic and may neutralize the highly cationic Bac5, thus accounting for the inactivation of the antibiotic activity observed in in vitro experiments. The structure of mature Bac5 agrees closely with the amino acid sequence previously determined, with an additional tripeptide tail predicting carboxyl-terminal amidation. A valyl residue is deduced at the cleavage site for the proteolytic maturation of proBac5, consistent with a previous observation showing elastase as the enzyme involved in this processing step. The region upstream of Bac5 reveals high identity to corresponding regions of two neutrophil antimicrobial polypeptides, CAP18 from rabbit and bovine indolicidin. The COOH-terminal sequences of these antibiotics are completely unrelated. The proregion also exhibits remarkable similarity to pig cathelin, an inhibitor of cathepsin L, indicating a common evolutionary origin

Characterization of Hearing Loss in Children with Mucopolysaccharidosis

Hearing impairment is common in patients with mucopolysaccharidoses (MPS) in the preschool age. Conductive or mixed hearing loss is the most frequent occurrence while the involvement of the inner ear or central auditory pathways may occur in more severe forms. A retrospective review of 82 children with MPS admitted at the Pediatric Department of the University of Milano Bicocca was performed to determine the incidence of otological symptoms. We focused particularly on audiological investigations in a subgroup of 47 children diagnosed before 6 years of age (MPS I, n = 11 patients; MPS II, n = 10; MPS III, n = 7; MPS IV, n = 14; MPS VI, n = 5). In 37 children, a magnetic resonance imaging (MRI) of the brain and cervical spine was also performed in order to correlate the audiological findings with the imaging of the middle and inner ear. A total of 40 out of 47 children (86%) showed some degree of hearing impairment: sensorineural or mixed hearing loss in 23 cases (48.93%) and retrocochlear in 4 (8.51%). MRI ascertained multiple CNS abnormalities in 13 (35.3%): dilated perivascular spaces in 5 (38.5%); dilated ventricular cavities in 5 (38.5%); demyelinated and gliotic areas in 3 (23.0%). Conversely, one-fourth of the children’s inner ears showed some morphological anomaly (24.3%)

Confirmation of increased and more severe adolescent mental health-related in-patient admissions in the COVID-19 pandemic aftermath: A 2-year follow-up study

: COVID-19 pandemic may have affected youth's mental wellbeing. Youth admissions for mental health emergencies over the 2-year period following the COVID-19 outbreak (March 2020-February 2022) were compared to those occurring in the same period of 2018-2020, with reference to individual and clinical data. The study identified 30 admissions in the pre-pandemic period and 65 (+116.7%) in the post-pandemic period, with the latter being younger, less likely to have a personal psychiatric history, and more likely to receive psychopharmacological treatment. A higher likelihood of earlier, ex novo psychiatric manifestations, requiring medication to reach clinical stability, in the post-COVID era, is suggested

Bovine Neutrophil Antibiotic Peptides and Their Precursors: Structure and Role in Innate Immunity

Four peptides were characterized in extracts of bovine neutrophil granules: an Arg-rich dodecapeptide, maintained in a cyclic structure by a disulfide bridge; a Trp-rich tridecapeptide named indo- licidin; and two 43- and 59 amino acids long peptides, named Bac5 and Bac7, with frequent repeats of the triplets Arg-Pro-Pro and Pro-Arg-Pro, respectively. The full length cDNA of the first three of these peptides was characterized recently. Sequence analysis showed that the prosequences of the predicted precursors of all the three peptides are highly identical and exhibited also a remarkable similarity to cathelin, a porcine inhibitor of cathepsin L. Purified proBacö actually proved in in vitro assays to inhibit cathepsin L, but not other cysteine proteinases such as cathepsin B. Unlike proBacö, proBac7 is selectively chemotactic to monocytes. Several fragments of Bac5 and Bac7 (from 6 to 35 residues) were synthesized by the Fmoc method. The results of antibacterial assays show that the N-terminal portion, the most cationic one in both Bac5 and Bac7, is essential for the antimicrobial activity and that the minimal length necessary to arrest the growth of susceptible bacteria is 18-20 residues

Unacylated ghrelin does not alter mitochondrial function, redox state and triglyceride content in rat liver in vivo

Summary Changes in liver mitochondrial function with more oxidized redox state and enhanced inflammation may contribute to the onset of obesity- and insulin resistance-associated hepatic complications, including non-alcoholic fatty liver disease and steato-hepatitis. Unacylated ghrelin (UnAG) is a gastric hormone reported to be associated with lower oxidative stress in different cell types, but its potential effects on liver mitochondrial function, redox state and inflammation in vivo remains undetermined. We investigated the impact of chronic UnAG overexpression (Tg Myh6/Ghrl) leading to systemic upregulation of circulating hormone on mitochondrial ATP production, redox state (oxidized-to-total glutathione) and inflammation markers in lean mice. Compared to wild-type animals (wt), Tg Myh6/Ghrl had superimposable liver weight, triglyceride content and plasma lipid profile. Liver mitochondrial enzyme activities and ATP production as well as oxidized-to-total glutathione were also similar in the two groups. In addition, no differences were observed in tissue inflammation marker TNF-alpha between wild-type and Tg Myh6/Ghrl animals. Thus, chronic systemic UnAG upregulation does not alter liver triglyceride content, mitochondrial function, redox state and inflammation markers in lean mice. These findings do not support a major role of UnAG as a physiological modulator of in vivo liver oxidative-lipid metabolism and inflammation

Natural Variation of Model Mutant Phenotypes in Ciona intestinalis

BACKGROUND: The study of ascidians (Chordata, Tunicata) has made a considerable contribution to our understanding of the origin and evolution of basal chordates. To provide further information to support forward genetics in Ciona intestinalis, we used a combination of natural variation and neutral population genetics as an approach for the systematic identification of new mutations. In addition to the significance of developmental variation for phenotype-driven studies, this approach can encompass important implications in evolutionary and population biology. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report a preliminary survey for naturally occurring mutations in three geographically interconnected populations of C. intestinalis. The influence of historical, geographical and environmental factors on the distribution of abnormal phenotypes was assessed by means of 12 microsatellites. We identified 37 possible mutant loci with stereotyped defects in embryonic development that segregate in a way typical of recessive alleles. Local populations were found to differ in genetic organization and frequency distribution of phenotypic classes. CONCLUSIONS/SIGNIFICANCE: Natural genetic polymorphism of C. intestinalis constitutes a valuable source of phenotypes for studying embryonic development in ascidians. Correlating genetic structure and the occurrence of abnormal phenotypes is a crucial focus for understanding the selective forces that shape natural finite populations, and may provide insights of great importance into the evolutionary mechanisms that generate animal diversity

Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register

Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations