Karl Ocius

Front Neurosci. 2022 Dec 22;16:1056785. doi: 10.3389/fnins.2022.1056785. eCollection 2022.

ABSTRACT

BACKGROUND: Gut microbiome has recently been recognized as an important environmental factor affecting the occurrence and development of unruptured intracranial aneurysms (UIA). This study aimed to investigate the relationship between gut microbiome and symptomatic UIA, which is a predictor of instability and a high propensity to rupture.

METHODS: A total of 132 patients including 86 asymptomatic UIA and 46 symptomatic UIA were recruited in the study. The composition of gut bacterial communities was determined by 16S ribosomal RNA gene sequencing. In addition, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to predict the functional composition of the gut microbiome.

RESULTS: There is no difference in the fecal microbial alpha diversity between symptomatic and asymptomatic UIA, but gut microbiome composition changed significantly. At the order level, the relative abundance of Clostridiales was significantly enriched in the symptomatic compared with asymptomatic UIA (p = 0.043). In addition, similar alterations were observed at the family levels of Ruminococcaceae. The Linear discriminant analysis (LEfSe) revealed Fournierella, Ruthenibacterium, and Anaerotruncus as discriminative features in the symptomatic group. Notably, functional differences in gut microbiome of patients with symptomatic UIA included decreased propionate metabolism pathway and enrichment of peptidoglycan biosynthesis pathways.

CONCLUSION: The present study comprehensively characterizes gut microbiome in a large cohort of different risk statuses of UIA patients and demonstrates the potential biological function of gut microbiome involved in the development of UIA. It may provide additional benefits in guiding UIA management and improving patient outcomes.

PMID:36620449 | PMC:PMC9814123 | DOI:10.3389/fnins.2022.1056785

Front Microbiol. 2022 Dec 21;13:1056608. doi: 10.3389/fmicb.2022.1056608. eCollection 2022.

ABSTRACT

Mycobacterium tuberculosis possesses a dynamic cell envelope, which consists of a peptidoglycan layer, a mycolic acid layer, and an arabinogalactan polysaccharide. This envelope possesses a highly complex and unique structure representing a barrier that protects and assists the growth of M. tuberculosis and allows its adaptation to the host. It regulates the immune response of the host cells, causing their damage. Therefore, the cell envelope of M. tuberculosis is an attractive target for vaccine and drug development. The emergence of multidrug-resistant as well as extensively drug resistant tuberculosis and co-infection with HIV prevented an effective control of this disease. Thus, the discovery and development of new drugs is a major keystone for TB treatment and control. This review mainly summarizes the development of drug enzymes involved in the biosynthesis of the cell wall in M. tuberculosis, and other potential drug targets in this pathway, to provide more effective strategies for the development of new drugs.

PMID:36620019 | PMC:PMC9810820 | DOI:10.3389/fmicb.2022.1056608

J Bacteriol. 2022 Dec 21:e0042422. doi: 10.1128/jb.00424-22. Online ahead of print.

ABSTRACT

The peptidoglycan of mycobacteria has two types of direct cross-links, classical 4-3 cross-links that occur between diaminopimelate (DAP) and alanine residues, and nonclassical 3-3 cross-links that occur between DAP residues on adjacent peptides. The 3-3 cross-links are synthesized by the concerted action of d,d-carboxypeptidases and l,d-transpeptidases (Ldts). Mycobacterial genomes encode several Ldt proteins that can be classified into six classes based upon sequence identity. As a group, the Ldt enzymes are resistant to most β-lactam antibiotics but are susceptible to carbapenem antibiotics, with the exception of LdtC, a class 5 enzyme. In previous work, we showed that loss of LdtC has the greatest effect on the carbapenem susceptibility phenotype of Mycobacterium smegmatis (also known as Mycolicibacterium smegmatis) compared to other ldt deletion mutants. In this work, we show that a M. smegmatis mutant lacking the five ldt genes other than ldtC has a wild-type phenotype with the exception of increased susceptibility to rifampin. In contrast, a mutant lacking all six ldt genes has pleiotropic cell envelope defects, is temperature sensitive, and has increased susceptibility to a variety of antibiotics. These results indicate that LdtC is capable of functioning as the sole l,d-transpeptidase in M. smegmatis and suggest that it may represent a carbapenem-resistant pathway for peptidoglycan biosynthesis. IMPORTANCE Mycobacteria have several enzymes to catalyze nonclassical 3-3 linkages in the cell wall peptidoglycan. Understanding the biology of these cross-links is important for the development of antibiotic therapies to target peptidoglycan biosynthesis. Our work provides evidence that LdtC can function as the sole enzyme for 3-3 cross-link formation in M. smegmatis and suggests that LdtC may be part of a carbapenem-resistant l,d-transpeptidase pathway.

PMID:36541811 | DOI:10.1128/jb.00424-22

J Sci Food Agric. 2022 Dec 11. doi: 10.1002/jsfa.12383. Online ahead of print.

NO ABSTRACT

PMID:36502373 | DOI:10.1002/jsfa.12383

Nutrients. 2022 Dec 2;14(23):5140. doi: 10.3390/nu14235140.

NO ABSTRACT

PMID:36501169 | DOI:10.3390/nu14235140

Drugs. 2022 Dec;82(18):1695-1715. doi: 10.1007/s40265-022-01817-w. Epub 2022 Dec 7.

NO ABSTRACT

PMID:36479687 | PMC:PMC9734533 | DOI:10.1007/s40265-022-01817-w

Biochim Biophys Acta Mol Cell Res. 2022 Dec 5;1870(2):119406. doi: 10.1016/j.bbamcr.2022.119406. Online ahead of print.

NO ABSTRACT

PMID:36473551 | DOI:10.1016/j.bbamcr.2022.119406

J Enzyme Inhib Med Chem. 2023 Dec;38(1):387-397. doi: 10.1080/14756366.2022.2149745.

NO ABSTRACT

PMID:36446617 | PMC:PMC9718554 | DOI:10.1080/14756366.2022.2149745

Proc Natl Acad Sci U S A. 2022 Dec 13;119(50):e2214599119. doi: 10.1073/pnas.2214599119. Epub 2022 Dec 5.

NO ABSTRACT

PMID:36469781 | DOI:10.1073/pnas.2214599119

World J Microbiol Biotechnol. 2022 Dec 1;39(1):31. doi: 10.1007/s11274-022-03475-2.

NO ABSTRACT

PMID:36454347 | DOI:10.1007/s11274-022-03475-2

Nat Immunol. 2022 Dec 1. doi: 10.1038/s41590-022-01354-4. Online ahead of print.

ABSTRACT

Aside from centrally induced trained immunity in the bone marrow (BM) and peripheral blood by parenteral vaccination or infection, evidence indicates that mucosal-resident innate immune memory can develop via a local inflammatory pathway following mucosal exposure. However, whether mucosal-resident innate memory results from integrating distally generated immunological signals following parenteral vaccination/infection is unclear. Here we show that subcutaneous Bacillus Calmette-Guérin (BCG) vaccination can induce memory alveolar macrophages (AMs) and trained immunity in the lung. Although parenteral BCG vaccination trains BM progenitors and circulating monocytes, induction of memory AMs is independent of circulating monocytes. Rather, parenteral BCG vaccination, via mycobacterial dissemination, causes a time-dependent alteration in the intestinal microbiome, barrier function and microbial metabolites, and subsequent changes in circulating and lung metabolites, leading to the induction of memory macrophages and trained immunity in the lung. These data identify an intestinal microbiota-mediated pathway for innate immune memory development at distal mucosal tissues and have implications for the development of next-generation vaccine strategies against respiratory pathogens.

PMID:36456739 | DOI:10.1038/s41590-022-01354-4

Pharmacol Res. 2022 Nov 29:106586. doi: 10.1016/j.phrs.2022.106586. Online ahead of print.

NO ABSTRACT

PMID:36460280 | DOI:10.1016/j.phrs.2022.106586

ACS Chem Biol. 2022 Nov 22. doi: 10.1021/acschembio.2c00741. Online ahead of print.

ABSTRACT

Bacterial cell wall peptidoglycan is essential for viability, and its synthesis is targeted by antibiotics, including penicillin. To determine how peptidoglycan homeostasis controls cell architecture, growth, and division, we have developed novel labeling approaches. These are compatible with super-resolution fluorescence microscopy to examine peptidoglycan synthesis, hydrolysis, and the localization of the enzymes required for its biosynthesis (penicillin binding proteins (PBPs)). Synthesis of a cephalosporin-based fluorescent probe revealed a pattern of PBPs at the septum during division, supporting a model of dispersed peptidoglycan synthesis. Metabolic and hydroxylamine-based probes respectively enabled the synthesis of glycan strands and associated reducing termini of the peptidoglycan to be mapped. Foci and arcs of reducing termini appear as a result of both synthesis of glycan strands and glucosaminidase activity of the major peptidoglycan hydrolase, SagB. Our studies provide molecular level details of how essential peptidoglycan dynamics are controlled during growth and division.

PMID:36414253 | DOI:10.1021/acschembio.2c00741

Front Chem. 2022 Nov 7;10:1020387. doi: 10.3389/fchem.2022.1020387. eCollection 2022.

NO ABSTRACT

PMID:36426099 | PMC:PMC9680013 | DOI:10.3389/fchem.2022.1020387

World J Microbiol Biotechnol. 2022 Nov 21;39(1):18. doi: 10.1007/s11274-022-03457-4.

ABSTRACT

Methicillin-resistant Staphylococcus aureus (MRSA) is a zoonotic antibiotic-resistant pathogen that negatively impacts society from medical, veterinary, and societal standpoints. The search for alternative therapeutic strategies and innovative anti-infective agents is urgently needed. Among the pathogenic mechanisms of Staphylococcus aureus (S. aureus), sortase A is a virulence factor of great concern because it is highly linked with the ability of MRSA to invade the host. In this study, we identified that rhodionin, a natural compound of flavonoid glucosides, effectively inhibited the activity of SrtA without affecting the survival and growth of bacteria, and its half maximal inhibitory concentration (IC₅₀) value was 22.85 μg/mL. In vitro, rhodionin prominently attenuated the virulence-related phenotype of SrtA by reducing the adhesion of S. aureus to fibrinogen, reducing the capacity of protein A (SpA) on the bacterial surface and biofilm formation. Subsequently, fluorescence quenching and molecular docking were performed to verify that rhodionin directly bonded to SrtA molecule with K_A value of 6.22 × 10⁵ L/mol. More importantly, rhodionin showed a significant protective effect on mice pneumonia model and improved the survival rate of mice. According to the above findings, rhodionin achieved efficacy in the treatment of MRSA-induced infections, which holds promising potential to be developed into a candidate used for MRSA-related infections.

PMID:36409383 | DOI:10.1007/s11274-022-03457-4

J Microbiol Biotechnol. 2022 Oct 28;32(10):1284-1291. doi: 10.4014/jmb.2206.06007. Epub 2022 Oct 7.

ABSTRACT

The rise of methicillin-resistant Staphylococcus aureus (MRSA) has resulted in significant morbidity and mortality, and clinical treatment of MRSA infections has become extremely difficult. Sortase A (SrtA), a virulence determinant that anchors numerous virulence-related proteins to the cell wall, is a prime druggable target against S. aureus infection due to its crucial role in the pathogenicity of S. aureus. Here, we demonstrate that isovitexin, an active ingredient derived from a variety of traditional Chinese medicines, can reversibly inhibit SrtA activity in vitro with a low dose (IC₅₀=24.72 μg/ml). Fluorescence quenching and molecular simulations proved the interaction between isovitexin and SrtA. Subsequent point mutation experiments further confirmed that the critical amino acid positions for SrtA binding to isovitexin were Ala-92, Ile-182, and Trp-197. In addition, isovitexin treatment dramatically reduced S. aureus invasion of A549 cells. This study shows that treatment with isovitexin could alleviate pathological injury and prolong the life span of mice in an S. aureus pneumonia model. According to our research, isovitexin represents a promising lead molecule for the creation of anti-S. aureus medicines or adjuncts.

PMID:36224754 | PMC:PMC9668100 | DOI:10.4014/jmb.2206.06007

Arch Microbiol. 2022 Nov 1;204(11):684. doi: 10.1007/s00203-022-03294-x.

ABSTRACT

Inflammatory bowel disease includes ulcerative colitis and Crohn's disease, and is globally increasing. An appropriate model system is required to dissect the disease pathogenesis and drugs screening for adequate treatment. In the present study, we established a novel model of gut inflammation by injecting peptidoglycan from Staphylococcus aureus using laparotomic procedure. For this, three different doses of peptidoglycan, i.e., 2.5, 5 and 10 mg/kg body weight were used. The treatment effect was evaluated by studying the macrophage phagocytic function, spleen lymphocytes' proliferation and qRT-PCR for the assessment of peritoneal cells' gene expression. In addition, histological analysis of gut sections, gastric acidity, immunoglobulins and cytokines were assessed. There was significant increase in phagocytic activity in 10 mg/kg body weight PGN group. A dose dependent increase in spleen lymphocytes' proliferation and a significant increase in total acid secretion in 5 and 10 mg/kg body weight PGN treated rats were observed. In addition, a significant increment in TLR-2 and CD-14 mRNA expression in peritoneal cells, TNF-α, IL-6 and IFN-γ level and maximum distortion of gut architecture was observed in 10 mg/kg body weight PGN group. Hence, peptidoglycan from S. aureus can be used for establishing the screening model to study the action and mechanism of anti-inflammatory food products and drugs.

PMID:36318321 | DOI:10.1007/s00203-022-03294-x

Cell Surf. 2022 Oct 20;8:100085. doi: 10.1016/j.tcsw.2022.100085. eCollection 2022 Dec.

ABSTRACT

The bacterial cell wall is composed of a thick layer of peptidoglycan and cell wall polymers, which are either embedded in the membrane or linked to the peptidoglycan backbone and referred to as lipoteichoic acid (LTA) and wall teichoic acid (WTA), respectively. Modifications of the peptidoglycan or WTA backbone can alter the susceptibility of the bacterial cell towards cationic antimicrobials and lysozyme. The human pathogen Listeria monocytogenes is intrinsically resistant towards lysozyme, mainly due to deacetylation and O-acetylation of the peptidoglycan backbone via PgdA and OatA. Recent studies identified additional factors, which contribute to the lysozyme resistance of this pathogen. One of these is the predicted ABC transporter, EslABC. An eslB mutant is hyper-sensitive towards lysozyme, likely due to the production of thinner and less O-acetylated peptidoglycan. Using a suppressor screen, we show here that suppression of eslB phenotypes could be achieved by enhancing peptidoglycan biosynthesis, reducing peptidoglycan hydrolysis or alterations in WTA biosynthesis and modification. The lack of EslB also leads to a higher negative surface charge, which likely stimulates the activity of peptidoglycan hydrolases and lysozyme. Based on our results, we hypothesize that the portion of cell surface exposed WTA is increased in the eslB mutant due to the thinner peptidoglycan layer and that latter one could be caused by an impairment in UDP-N-acetylglucosamine (UDP-GlcNAc) production or distribution.

PMID:36304571 | PMC:PMC9593813 | DOI:10.1016/j.tcsw.2022.100085

Mol Microbiol. 2022 Oct 29. doi: 10.1111/mmi.14996. Online ahead of print.

ABSTRACT

The peptidoglycan (PG) layer of bacterial cells is essential for maintaining the cell shape and survival of cells; therefore, the synthesis of PG needs to be spatiotemporally controlled. While it is well established that PG synthesis is mediated posttranslationally through interactions between PG synthases and their cognate partners, much less is known about the transcriptional regulation of genes encoding these synthases. Based on a previous finding that the Gram-negative bacterium Shewanella oneidensis lacking the prominent PG synthase exhibits impaired cell wall integrity, we performed genetic selections to isolate the suppressors. We discovered that disrupting the sspA gene encoding stringent starvation protein A (SspA) is sufficient to suppress compromised PG. SspA serves as a transcriptional repressor that regulates the expression of the two types of PG synthases, class A penicillin-binding proteins and SEDS/bPBP protein complexes. SspA is an RNA polymerase-associated protein, and its regulation involves interactions with the σ⁷⁰ -RNAP complex and an antagonistic effect of H-NS, a global nucleoid-associated protein. We also present evidence that the regulation of PG synthases by SspA is conserved in Escherichia coli, adding a new dimension to the current understanding of PG synthesis and its regulation.

PMID:36308522 | DOI:10.1111/mmi.14996

Front Oncol. 2022 Sep 27;12:970967. doi: 10.3389/fonc.2022.970967. eCollection 2022.

ABSTRACT

According to the WHO, cancer is the second leading cause of death in the world. This is an important global problem and a major challenge for researchers who have been trying to find an effective anticancer therapy. A large number of newly discovered compounds do not exert selective cytotoxic activity against tumorigenic cells and have too many side effects. Therefore, research on muramyl dipeptide (MDP) analogs has attracted interest due to the urgency for finding more efficient and safe treatments for oncological patients. MDP is a ligand of the cytosolic nucleotide-binding oligomerization domain 2 receptor (NOD2). This molecule is basic structural unit that is responsible for the immune activity of peptidoglycans and exhibits many features that are important for modern medicine. NOD2 is a component of the innate immune system and represents a promising target for enhancing the innate immune response as well as the immune response against cancer cells. For this reason, MDP and its analogs have been widely used for many years not only in the treatment of immunodeficiency diseases but also as adjuvants to support improved vaccine delivery, including for cancer treatment. Unfortunately, in most cases, both the MDP molecule and its synthesized analogs prove to be too pyrogenic and cause serious side effects during their use, which consequently exclude them from direct clinical application. Therefore, intensive research is underway to find analogs of the MDP molecule that will have better biocompatibility and greater effectiveness as anticancer agents and for adjuvant therapy. In this paper, we review the MDP analogs discovered in the last 10 years that show promise for antitumor therapy. The first part of the paper compiles the achievements in the field of anticancer vaccine adjuvant research, which is followed by a description of MDP analogs that exhibit promising anticancer and antiproliferative activity and their structural changes compared to the original MDP molecule.

PMID:36237313 | PMC:PMC9551026 | DOI:10.3389/fonc.2022.970967

Microbiol Spectr. 2022 Oct 10:e0112822. doi: 10.1128/spectrum.01128-22. Online ahead of print.

ABSTRACT

Streptococcus agalactiae is a common pathogen in aquaculture that disrupts the balance of the intestinal microbiota and threatens fish health, causing enormous losses to the aquaculture industry. In this study, we isolated and screened a Lactococcus lactis KUST48 (LLK48) strain with antibacterial effect against S. agalactiae in vitro and used it as a potential probiotic to explore its therapeutic effect on zebrafish (Danio rerio) infected with S. agalactiae. This study divided zebrafish into 3 groups: control group, injected with phosphate-buffered saline; infection group, injected with S. agalactiae; and treatment group, treated with LLK48 after S. agalactiae injection. Then, the 16S rRNA gene sequences of the intestinal microbiota of these 3 groups were sequenced using Illumina high-throughput sequencing technology. The results showed that the relative abundance of intestinal bacteria was significantly decreased in the infection group, and a high relative abundance of S. agalactiae was observed. The relative abundance of the intestinal microbiota was increased in the treatment group, with a decrease in the relative abundance of S. agalactiae compared to that in the control group. In the Cluster of Orthologous Groups of proteins function classification, the relative abundance of each biological function in the infection group was significantly lower than that of the control and treatment groups, showing that LLK48 has a positive therapeutic effect on zebrafish infected with S. agalactiae. This study provides a foundation for exploring the pathogenic mechanism of S. agalactiae on fish and their intestinal symbionts, and also presents a new approach for the treatment of S. agalactiae infections in fish aquaculture systems. IMPORTANCE L. lactis KUST48 (LLK48) with a bacteriostatic effect against S. agalactiae was isolated from tilapia intestinal tracts. S. agalactiae infection significantly reduced the relative abundance of intestinal bacteria and various physiological functions in zebrafish intestines. LLK48 demonstrated infection and subsequent therapeutic effects on the S. agalactiae infection in the zebrafish intestine. Therefore, the potential probiotic LLK48 can be considered as a therapeutic treatment for S. agalactiae infections in aquaculture, which can reduce the use of antibiotics and help maintain fish health.

PMID:36214699 | DOI:10.1128/spectrum.01128-22

Front Cell Infect Microbiol. 2022 Sep 23;12:943545. doi: 10.3389/fcimb.2022.943545. eCollection 2022.

ABSTRACT

Drug resistant tuberculosis contributes significantly to the global burden of antimicrobial resistance, often consuming a large proportion of the healthcare budget and associated resources in many endemic countries. The rapid emergence of resistance to newer tuberculosis therapies signals the need to ensure appropriate antibiotic stewardship, together with a concerted drive to develop new regimens that are active against currently circulating drug resistant strains. Herein, we highlight that the current burden of drug resistant tuberculosis is driven by a combination of ongoing transmission and the intra-patient evolution of resistance through several mechanisms. Global control of tuberculosis will require interventions that effectively address these and related aspects. Interrupting tuberculosis transmission is dependent on the availability of novel rapid diagnostics which provide accurate results, as near-patient as is possible, together with appropriate linkage to care. Contact tracing, longitudinal follow-up for symptoms and active mapping of social contacts are essential elements to curb further community-wide spread of drug resistant strains. Appropriate prophylaxis for contacts of drug resistant index cases is imperative to limit disease progression and subsequent transmission. Preventing the evolution of drug resistant strains will require the development of shorter regimens that rapidly eliminate all populations of mycobacteria, whilst concurrently limiting bacterial metabolic processes that drive drug tolerance, mutagenesis and the ultimate emergence of resistance. Drug discovery programs that specifically target bacterial genetic determinants associated with these processes will be paramount to tuberculosis eradication. In addition, the development of appropriate clinical endpoints that quantify drug tolerant organisms in sputum, such as differentially culturable/detectable tubercle bacteria is necessary to accurately assess the potential of new therapies to effectively shorten treatment duration. When combined, this holistic approach to addressing the critical problems associated with drug resistance will support delivery of quality care to patients suffering from tuberculosis and bolster efforts to eradicate this disease.

PMID:36211964 | PMC:PMC9538507 | DOI:10.3389/fcimb.2022.943545