Human salivary MUC7 mucin fragment and its analogues. Coordination and biological studies

The Potential Antimicrobial Action of Human Mucin 7 15-Mer Peptide and Its Metal Complexes

Mucin 7 (encoded byMUC7) is a human salivary protein that has a role in the natural immune system. Fragments of mucin 7 exhibit antimicrobial activity against bacteria and yeast. Although the antimicrobial properties of peptides have been known and studied for decades, the exact mechanism of action of antimicrobial peptides (AMPs) is still unclear. It is known that some AMPs require divalent metal ions to activate their activity. Herein, we investigated three 15-mer MUC7 peptides, one of which (mother peptide, sequence, L3) is a synthetic analog of a fragment naturally excised from MUC7 (with His3, His8, and His 14) and its two structural analogs, containing only two histidine residues, His3, His13 and His8, His13 (L2 and L1, respectively). Since there is a correlation between lipophilicity, the presence of metal ions (such as Cu(II) and Zn(II)) and antimicrobial activity of AMP, antimicrobial properties of the studied peptides, as well as their complexes with Cu(II) and Zn(II) ions, were tested for activity against Gram-positive (Enterococcus faecalis, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria and fungi (Candida albicans). The results were correlated with their lipophilicity. Coordination and thermodynamic studies (potentiometry, UV-Vis, CD) revealed the formation of mainly mononuclear complexes in solution for all studied systems with different stability in the physiological pH range.

Interpretation of the mucous plug through sialendoscopy

OBJECTIVE

The purpose of this manuscript is to highlight the behaviour of mucus inside the ducts of the major salivary glands, in presence of typical pathologies, through images obtained with sialendoscopy.

SUBJECT

The authors present and comment on some sialendoscopies that show mucous plug in the ducts of the major salivary glands.

RESULTS

In primary Sjogren's syndrome, mucous plugs confirm the qualitative anomaly of the mucins and acidification saliva. Instead, salivary calculations behave like foreign bodies that generate mechanical pressure and friction on the duct walls of major salivary glands, so mucus deposits in the duct in its defence; in case of infected stone, mucous plugs are formed also with the function of protecting the ducts from the aggression of germs. During sialadenitis, there is a conflict between mucus and bacteria which explains sialendoscopic evidence such as white duct walls and mucous plugs.

CONCLUSIONS

The study of the salivary ducts through sialendoscopy often confirms the clinical diagnosis or hypothesize it. During its execution, it is necessary not only to liberate the ducts of the major salivary glands but also analyse the appearance of the mucous plugs and the ductal walls as they are useful to guide the physician towards diagnosis.

Changes in salivary proteins can reflect beneficial physiological effects of ejaculation in the dog

The objective of this study was to study the changes in salivary proteins that occur in the dog after the ejaculation process. Saliva samples from eight dogs before and after induced ejaculation were analyzed by proteomic using Tandem Mass Tag (TMT) labeling and LC-MS/MS analysis. A total of 33 salivary proteins showed significant changes after the ejaculation process. The up-regulated proteins that showed changes of higher magnitude were mucin-7 (MUC-7), peroxiredoxin-4 (PRDX4) and galectin-3 (LEGALS3) whereas proteins such as alpha-1-acid glycoprotein (A1G1) and alpha-1B-glycoprotein (A1BG) were the most down-regulated. MUC-7 and PRDX4 expression in saliva after ejaculation could be associated with the protective "environment" created by the organism to exert pr 3o-fertility activities and antioxidants benefits in spermatozoa. Also LEGALS3 increment could be associated with an improvement of wellbeing and could contribute to a positive global effect in the body. Down-regulations of A1G1 and A1GB proteins found in saliva after ejaculation could be associated with a reduction in systemic inflammation. Overall it can be concluded that, changes in proteins in saliva that are produced after ejaculation can reflect a state of increase immune defenses, improvement of antioxidant status and low inflammation.

Metal-Peptide Complexes as Promising Antibiotics to Fight Emerging Drug Resistance: New Perspectives in Tuberculosis

In metal-peptide interactions, cations form stable complexes through bonds with coordinating groups as side chains of amino acids. These compounds, among other things, exert a wide variety of antimicrobial activities through structural changes of peptides upon metal binding and redox chemistry. They exhibit different mechanisms of action (MOA), including the modification of DNA/RNA, protein and cell wall synthesis, permeabilization and modulation of gradients of cellular membranes. Nowadays, the large increase in antibiotic resistance represents a crucial problem to limit progression at the pandemic level of the diseases that seemed nearly eradicated, such as tuberculosis (Tb). Mycobacterium tuberculosis (Mtb) is intrinsically resistant to many antibiotics due to chromosomal mutations which can lead to the onset of novel strains. Consequently, the maximum pharmaceutical effort should be focused on the development of new therapeutic agents and antimicrobial peptides can represent a valuable option as a copious source of potential bioactive compounds. The introduction of a metal center can improve chemical diversity and hence specificity and bioavailability while, in turn, the coordination to peptides of metal complexes can protect them and enhance their poor water solubility and air stability: the optimization of these parameters is strictly required for drug prioritization and to obtain potent inhibitors of Mtb infections with novel MOAs. Here, we present a panoramic review of the most recent findings in the field of metal complex-peptide conjugates and their delivery systems with the potential pharmaceutical application as novel antibiotics in Mtb infections.