Biomedical subjects

Diane Bimczok

Publications and source records attributed to Diane Bimczok.

5 recordsLinked to original sources

PubMed2026

H-NOX and NosP Regulate Flagellar Protein and Virulence Factor Production in Vibrio cholerae.

The ability of Vibrio cholerae to transition between motile and sessile forms in the environment and in the host is critical to its survival and virulence. The molecular cues, sensor proteins, and signaling pathways mediating these transitions are highly complex and often overlapping. Nevertheless, a detailed understanding of them is critical for understanding the persistence and pathogenesis of this deadly pathogen. Nitric oxide (NO) functions as an important signaling molecule in many bacteria, affecting biofilm formation, motility, and virulence, often through interaction with heme protein sensors. The genome of V. cholerae encodes two such sensors called H-NOX and NosP. Here we constructed a Δhnox/nosP mutant and employed a multi-omics methodology that combines tandem-mass-tag (TMT)-based quantitative proteomics, phosphoproteomics, and targeted metabolomics to investigate the function of these sensors. A set of 258 proteins was differentially expressed in the mutant that included many proteins involved in flagellar biosynthesis and motility as well as critical virulence factors, iron acquisition systems, and metabolic enzymes. Many of the identified genes are also part of the ferric uptake regulator (Fur) regulon and iron-dependent transcriptional repression of several Fur targets was disrupted. Phosphoproteomics analysis also revealed proteins involved in motility and virulence as differentially phosphorylated in the mutant strain. In most cases, these phosphoproteins have not been previously observed and provide a wealth of new targets for investigating mechanisms of V. cholerae signaling. Taken together, this work illustrates a role for H-NOX and NosP in promoting factors important for infection while suppressing those important for environmental survival, suggesting a function in priming the organism for infection and/or maintaining the infectious phenotype.

Journal Article↗

PubMed2026

Physical, chemical, and structural properties of human gastric organoid-derived mucus.

The gastric mucus layer protects the epithelium from gastric acid and ingested pathogens. However, studies of human gastric mucus have been limited due to poor accessibility of native human mucus and the abundance of contaminants in these samples. Here, we explored the potential of human gastric organoids as models for mucus production. Immunofluorescence staining confirmed that the organoids produced mucus containing MUC5AC and MUC6. The luminal mucus had viscoelastic properties similar to those of native human gastric mucus, as determined by particle tracking microrheology. To collect organoid-produced gastric mucus, termed bioengineered gastric mucus (BGM), organoids were cultured as monolayers at the air-liquid interface (ALI), and apically secreted mucus was harvested and analyzed by MUC5AC ELISA, proteomics, cryo-field emission scanning electron microscopy (CryoFE-SE), and rheometry. BGM contained high-molecular weight molecules also found in native gastric mucus. Proteomic analysis confirmed that BGM contained MUC5AC, MUC6, MUC1, and other stomach-specific molecules such as pepsin C, trefoil factor 2, and gastrokine. CryoFE-SE showed that both BGM and native mucus had a porous structure and a characteristic honeycomb scaffold. However, the viscosity of the BGM was generally lower than that of native human gastric mucus, and BGM failed to exhibit gelation at low pH. Collectively, these findings demonstrate the potential as well as some limitations of BGM as an accessible model system for human gastric mucus.NEW & NOTEWORTHY We demonstrate the structural and functional similarities of organoid-derived gastric mucus and native mucus collected from human patients. The bioengineered gastric mucus mimics its native counterpart in its proteomic profile and physical architecture. This work highlights the translational potential of organoid-derived mucus for functional investigations of the human gastric mucus layer.

Humans↗

PubMed2006

Phenotype and distribution of dendritic cells in the porcine small intestinal and tracheal mucosa and their spatial relationship to epithelial cells.

Dendritic cells (DC) as key mediators of tolerance and immunity perform crucial immunosurveillance functions at epithelial surfaces. In order to induce an immune response, the DC have to gain access to antigens present at the luminal surface of mucosal epithelia. The mechanisms of this process are still largely unclear. We have therefore analysed the distribution of DC in the porcine intestinal and respiratory mucosa and their spatial relationship to epithelial cells by immunohistology. Immunofluorescence analysis of cryosections taken from jejunal Peyer's patches and double-stained for DC and M cells (specialised for antigen uptake) have revealed that 35.2+/-3.9% of M cells are located directly adjacent to DC in the subepithelial domes, representing possible antigen transfer sites. In normal jejunal villi, a rare population of lamina propria DC extending cytoplasmic processes between enterocytes has been identified as a possible correlate for direct luminal antigen uptake. Like small intestinal DC, DC in the porcine trachea mostly co-express CD16 with MHC-II. Tracheal DC have been found at high densities both above and below the basement membrane (BM) of the tracheal epithelium, with 32.4 DC/mm BM and 23.0 DC/mm BM, respectively. The intraepithealial DC population forms a dense network, with many of the cytoplasmic processes being directed towards the tracheal lumen. Our morphological analyses indicate that DC at mucosal epithelial sites are ideally positioned for the uptake of luminal antigens.

Animals↗

PubMed2006

Lymphocyte migration studies.

For maintenance of immunity and tolerance, the organs and tissues of the organism are connected by migrating lymphoid cells. Understanding lymphocyte migration is essential for many disorders and diseases-- especially in the mucosa-lined organs. Detailed analyses of migrating lymphocytes have been performed in many species, especially in laboratory animals. However, important experiments in lymphocyte migration have been carried out in large animals, for example sheep, cattle and pigs. These species allow experimental procedures like in situ-organ labelling, lymphocyte retransfusion studies or lymph vessel cannulations. Such studies have made an important contribution to the understanding of the overall principles of lymphocyte migration especially in the mucosal immune system. Major results on the specific migration of naïve and memory T cells through lymphoid organs, the re-distribution of gamma/delta T cells in the intestinal immune system and the emigration of newly produced B cells from the ileal Peyer's patches have been obtained in large animals. Since there are growing numbers of markers for large animals, and molecular biology methods are available in these species, experiments in large animals will be an essential tool for the understanding of lymphocyte migration especially in mucosal organs.

Animals↗

PubMed2005

Site-specific expression of CD11b and SIRPalpha (CD172a) on dendritic cells: implications for their migration patterns in the gut immune system.

Dendritic cells (DC) in the intestinal tract play a major role in directing the mucosal immune system towards tolerance or immunity. We analyzed whether different mucosal DC subsets in pigs have specific functions, localizations, or migration patterns in vivo. Therefore, we collected physiologically migrating DC by pseudo-afferent cannulation of the intestinal duct in eight Gottingen minipigs. Lymph DC were phenotypically and functionally characterized and compared to DC found on histological sections of porcine small intestine and mesenteric lymph nodes (MLN). Four different DC subpopulations were detected. Lamina propria (LP) DC were mainly CD11b(+) signal regulatory protein alpha (SIRPalpha)(+), DC in Peyer's patches were mainly CD11b(-)/SIRPalpha(+) in subepithelial domes and CD11b(-)/SIRPalpha(-) in interfollicular regions, whereas MLN DC were largely CD11b(+)/SIRPalpha(-). Of these four subsets, only the CD11b(+)/SIRPalpha(+) DC and the CD11b(+)/SIRPalpha(-) DC were present in lymph. This suggests that DC migration to MLN largely originates from the LP. Lymph DC expressed high levels of MHC class II and costimulatory molecules and had a low capacity for FITC-dextran uptake, indicating a mature phenotype. However, lymph DC did not induce PBMC proliferation in MLR, and migration was not significantly influenced by mucosal antigen application.

Animals↗