Use of Recombinant Mucin Glycoprotein to Assess the Interaction of the Gastric Pathogen Helicobacter pylori with the Secreted Human Mucin MUC5AC

A physiologically relevant culture platform for long-term studies of in vitro gingival tissue

There is a clinical need to understand the etiologies of periodontitis, considering the growing socio-economic impact of the disease. Despite recent advances in oral tissue engineering, experimental approaches have failed to develop a physiologically relevant gingival model that combines tissue organization with salivary flow dynamics and stimulation of the shedding and non-shedding oral surfaces. Herein, we develop a dynamic gingival tissue model composed of a silk scaffold, replicating the cyto-architecture and oxygen profile of the human gingiva, along with a saliva-mimicking medium that reflected the ionic composition, viscosity, and non-Newtonian behavior of human saliva. The construct was cultured in a custom designed bioreactor, in which force profiles on the gingival epithelium were modulated through analysis of inlet position, velocity and vorticity to replicate the physiological shear stress of salivary flow. The gingival bioreactor supported the long-term in vivo features of the gingiva and improved the integrity of the epithelial barrier, critical against the invasion of pathogenic bacteria. Furthermore, the challenge of the gingival tissue with P. gingivalis lipopolysaccharide, as an in vitro surrogate for microbial interactions, indicated a greater stability of the dynamic model in maintaining tissue homeostasis and, thus, its applicability in long-term studies. The model will be integrated into future studies with the human subgingival microbiome to investigate host-pathogen and host-commensal interactions. STATEMENT OF SIGNIFICANCE: The major societal impact of human microbiome had reverberated up to the establishment of the Common Fund's Human Microbiome Project, that has the intent of studying the role of microbial communities in human health and diseases, including periodontitis, atopic dermatitis, or asthma and inflammatory bowel disease. In addition, these chronic diseases are emergent drivers of global socioeconomic status. Not only common oral diseases have been shown to be directly correlated with several systemic conditions, but they are differentially impacting some racial/ethnic and socioeconomic groups. To address this growing social disparity, the development of in vitro gingival model would provide a time and cost-effective experimental platform, able to mimic the spectrum of periodontal disease presentation, for the identification of predictive biomarkers for early-stage diagnosis.

Modeling mucus physiology and pathophysiology in human organs-on-chips

The surfaces of human internal organs are lined by a mucus layer that ensures symbiotic relationships with commensal microbiome while protecting against potentially injurious environmental chemicals, toxins, and pathogens, and disruption of this layer can contribute to disease development. Studying mucus biology has been challenging due to the lack of physiologically relevant human in vitro models. Here we review recent progress that has been made in the development of human organ-on-a-chip microfluidic culture models that reconstitute epithelial tissue barriers and physiologically relevant mucus layers with a focus on lung, colon, small intestine, cervix and vagina. These organ-on-a-chip models that incorporate dynamic fluid flow, air-liquid interfaces, and physiologically relevant mechanical cues can be used to study mucus composition, mechanics, and structure, as well as investigate its contributions to human health and disease with a level of biomimicry not possible in the past.

Investigating the Interaction of Helicobacter pylori with the Gastric Mucosa

Helicobacter pylori chronically infects the gastric mucosa of humans and diseases associated with infection include gastritis, peptic ulceration, and development of gastric cancer. The organism displays a distinct tropism for the gastric mucosa of humans and for the gastric mucin MUC5AC. While the majority of organisms are found in the mucus layer overlying the epithelial cells in the stomach, adherence of the organism to the gastric epithelium is necessary for the development of disease. The interaction of H. pylori with epithelial cells results in subversion of host cell signaling and induction of an inflammatory response. Factors that influence the outcome of infection include host genetics, environmental factors, and the phenotype of the infecting strain. In this chapter, we describe cell culture assays to assess the interaction of H. pylori with epithelial cells, immunofluorescent staining to detect H. pylori in infected human gastric biopsy specimens and the use of flow cytometry to detect mucin binding to H. pylori.

Mucins and Pathogenic Mucin-Like Molecules Are Immunomodulators During Infection and Targets for Diagnostics and Vaccines

Mucins and mucin-like molecules are highly O-glycosylated proteins present on the cell surface of mammals and other organisms. These glycoproteins are highly diverse in the apoprotein and glycan cores and play a central role in many biological processes and diseases. Mucins are the most abundant macromolecules in mucus and are responsible for its biochemical and biophysical properties. Mucin-like molecules cover various protozoan parasites, fungi and viruses. In humans, modifications in mucin glycosylation are associated with tumors in epithelial tissue. These modifications allow the distinction between normal and abnormal cell conditions and represent important targets for vaccine development against some cancers. Mucins and mucin-like molecules derived from pathogens are potential diagnostic markers and targets for therapeutic agents. In this review, we summarize the distribution, structure, role as immunomodulators, and the correlation of human mucins with diseases and perform a comparative analysis of mucins with mucin-like molecules present in human pathogens. Furthermore, we review the methods to produce pathogenic and human mucins using chemical synthesis and expression systems. Finally, we present applications of mucin-like molecules in diagnosis and prevention of relevant human diseases.

Biologic roles of the ABH and Lewis histo-blood group antigens part II: thrombosis, cardiovascular disease and metabolism

The ABH and Lewis antigens were among the first of the human red blood cell polymorphisms to be identified and, in the case of the former, play a dominant role in transfusion and transplantation. But these two therapies are largely twentieth-century innovations, and the ABH and related carbohydrate antigens are not only expressed on a very wide range of human tissues, but were present in primates long before modern humans evolved. Although we have learned a great deal about the biochemistry and genetics of these structures, the biological roles that they play in human health and disease are incompletely understood. This review and its companion, which appeared in a previous issue of Vox Sanguinis, will focus on a few of the biologic and pathologic processes which appear to be affected by histo-blood group phenotype. The first of the two reviews explored the interactions of two bacteria with the ABH and Lewis glycoconjugates of their human host cells, and described the possible connections between the immune response of the human host to infection and the development of the AB-isoagglutinins. This second review will describe the relationship between ABO phenotype and thromboembolic disease, cardiovascular disease states, and general metabolism.