The innate immune properties of airway mucosal surfaces are regulated by dynamic interactions between mucins and interacting proteins: the mucin interactome

Chronic lung diseases such as cystic fibrosis, chronic bronchitis and asthma, are characterized by hypersecretion and poor clearance of mucus, which are associated with poor prognosis and mortality. Little is known about the relationship between the biophysical properties of mucus and its molecular composition. The mucins MUC5B and MUC5AC are traditionally believed to generate the characteristic biophysical properties of airway mucus. However, the contribution of hundreds of globular proteins to the biophysical properties of mucus is not clear. Approximately one-third of the total mucus proteome comprises distinct, multi-protein complexes centered around airway mucins. These complexes constitute a discrete entity we call the “mucin interactome”. The data suggest that while the majority of these proteins interact with mucins via electrostatic and weak interactions, some interact through very strong hydrophobic and/or covalent interactions. Using reagents that interfere with protein-protein interactions, the complexes can be disassembled, and mucus rheology can be dramatically altered. Using MUC5B-glutathione S-transferase (GST) and MUC5B-galectin-3 as a representative of these interactions, we provide evidence that individual mucin protein interactions can alter the biophysical properties of mucus and modulate the biological function of the protein. We propose that the key mechano- and bio-active functions of mucus depend on the dynamic interactions between mucins and globular proteins. These observations challenge the paradigm that mucins are the only molecules that confer biophysical properties of mucus. These observations may ultimately lead to a greater understanding of the system and guide the development of strategies for more effective interventions using better therapeutic agents

The parallel lives of polysaccharides in food and pharmaceutical formulations

The present opinion article discusses how polysaccharide structures can be used in both food and pharmaceutical formulations. We distinguish two regions depending on moisture content where polysaccharides form structures with distinct functional properties. Some trends in key areas of active research are assessed and in particular edible films, encapsulation, polycrystalline polysaccharides, protein-polysaccharide coacervation and fluid gels. We unveil that the physicochemical principles that are shared across the food and pharmaceutical disciplines provide a great opportunity for cross-disciplinary collaboration. We finally argue that such co-operation will help tackling polysaccharide functionality issues that are encountered in both areas

Continuum-kinetic-microscopic model of lung clearance due to core-annular fluid entrainment

The human lung is protected against aspirated infectious and toxic agents by a thin liquid layer lining the interior of the airways. This airway surface liquid is a bilayer composed of a viscoelastic mucus layer supported by a fluid film known as the periciliary liquid. The viscoelastic behavior of the mucus layer is principally due to long-chain polymers known as mucins. The airway surface liquid is cleared from the lung by ciliary transport, surface tension gradients, and airflow shear forces. This work presents a multiscale model of the effect of airflow shear forces, as exerted by tidal breathing and cough, upon clearance. The composition of the mucus layer is complex and variable in time. To avoid the restrictions imposed by adopting a viscoelastic flow model of limited validity, a multiscale computational model is introduced in which the continuum-level properties of the airway surface liquid are determined by microscopic simulation of long-chain polymers. A bridge between microscopic and continuum levels is constructed through a kinetic-level probability density function describing polymer chain configurations. The overall multiscale framework is especially suited to biological problems due to the flexibility afforded in specifying microscopic constituents, and examining the effects of various constituents upon overall mucus transport at the continuum scale

BPI-fold (BPIF) containing/plunc protein expression in human fetal major and minor salivary glands.

The aim of this study was to determine expression, not previously described, of PLUNC (palate, lung, and nasal epithelium clone) (BPI-fold containing) proteins in major and minor salivary glands from very early fetal tissue to the end of the second trimester and thus gain further insight into the function of these proteins. Early fetal heads, and major and minor salivary glands were collected retrospectively and glands were classified according to morphodifferentiation stage. Expression of BPI-fold containing proteins was localized through immunohistochemistry. BPIFA2, the major BPI-fold containing protein in adult salivary glands, was detected only in the laryngeal pharynx; the lack of staining in salivary glands suggested salivary expression is either very late in development or is only in adult tissues. Early expression of BPIFA1 was seen in the trachea and nasal cavity with salivary gland expression only seen in late morphodifferentiation stages. BPIFB1 was seen in early neural tissue and at later stages in submandibular and sublingual glands. BPIFA1 is significantly expressed in early fetal oral tissue but BPIFB1 has extremely limited expression and the major salivary BPIF protein (BPIFA2) is not produced in fetal development. Further studies, with more sensitive techniques, will confirm the expression pattern and enable a better understanding of embryonic BPIF protein function

Restriction of HIV-1 Genotypes in Breast Milk Does Not Account for the Population Transmission Genetic Bottleneck That Occurs following Transmission

BACKGROUND. Breast milk transmission of HIV-1 remains a major route of pediatric infection. Defining the characteristics of viral variants to which breastfeeding infants are exposed is important for understanding the genetic bottleneck that occurs in the majority of mother-to-child transmissions. The blood-milk epithelial barrier markedly restricts the quantity of HIV-1 in breast milk, even in the absence of antiretroviral drugs. The basis of this restriction and the genetic relationship between breast milk and blood variants are not well established. METHODOLOGY/PRINCIPAL FINDINGS. We compared 356 HIV-1 subtype C gp160 envelope (env) gene sequences from the plasma and breast milk of 13 breastfeeding women. A trend towards lower viral population diversity and divergence in breast milk was observed, potentially indicative of clonal expansion within the breast. No differences in potential N-linked glycosylation site numbers or in gp160 variable loop amino acid lengths were identified. Genetic compartmentalization was evident in only one out of six subjects in whom contemporaneously obtained samples were studied. However, in samples that were collected 10 or more days apart, six of seven subjects were classified as having compartmentalized viral populations, highlighting the necessity of contemporaneous sampling for genetic compartmentalization studies. We found evidence of CXCR4 co-receptor using viruses in breast milk and blood in nine out of the thirteen subjects, but no evidence of preferential localization of these variants in either tissue. CONCLUSIONS/SIGNIFICANCE. Despite marked restriction of HIV-1 quantities in milk, our data indicate intermixing of virus between blood and breast milk. Thus, we found no evidence that a restriction in viral genotype diversity in breast milk accounts for the genetic bottleneck observed following transmission. In addition, our results highlight the rapidity of HIV-1 env evolution and the importance of sample timing in analyses of gene flow.National Institute of Child Health and Human Development; National Institutes of Health (R01 HD 39611, R01 HD 40777); International Maternal Pediatric Adolescent AIDS Clinical Trials Group (U01 AI068632-01); National Institutes of Health Cellular, Biochemical; Molecular Sciences Training Program Grant (T 32 067587

Interactions of pure aluminium hydrolytic species Keggin polyoxocations and hydroxide with biologically relevant molecules

The general purpose of this thesis is concerned with the intricate interactions of pure aluminium species with biomolecules. Pure aluminium reference systems (aluminium monomers, Keggin aluminium polyoxocations - Al13 and Al30, and aluminium hydroxide suspensions) were used for systematic mechanistic studies of the sol-gel transformation of aqueous solutions of aluminium-ions into aluminium (oxy) hydroxides induced by the addition of a 'soft base' - Trizma-base, which does not ionize fully in an aqueous solution. The conversion proceeds via forced hydrolysis-condensation of aluminium-ions into molecular clusters, structural conversion of aluminium Keggin-like polynuclear clusters into nanoparticles of aluminium (oxy) hydroxide, aggregation of primary nuclei of aluminium (oxy) hydroxide into larger clusters and finally the 'arrested growth' of the aggregates with the formation of the three-dimensional gel network. The next part of the study concentrated on the development and the optimisation of a potentiometric method for the determination of the 'formal' hydrolysis ratio of aluminium-containing solutions. The method made it possible to establish the aluminium speciation of the selected systems

Investigating the Therapeutic Potential of Salivary Proteins for Oral Diseases

ABSTRACT Saliva is responsible for the formation of the acquired enamel pellicle (AEP), a protein integument formed as a result of selective adsorption of salivary proteins to the enamel surface. The AEP demonstrates an important role for modulating dental erosion as a result of its physical properties, along with its salivary and exogenous protein composition (Chapter 2). In addition, individual proteins that comprise the AEP have important physiological functions. Histatin 5 (H5) has potent antifungal effect against C. albicans, the yeast responsible for the initiation of oral candidiasis. We designed an in vitro model and found, for the first time, that H5 adhered in the form of pellicle retains its antifungal activity on C. albicans (Chapter 3). As a pellicle precursor protein, H5 demonstrates high affinity for hydroxyapatite, the primary mineral component of enamel. We used atomic force microscopy (AFM) to determine adhesion forces between H5 and the hydroxyapatite surface to be stronger compared to our protein control, albumin. This knowledge can be applied in the design of therapeutic proteins, and the methodology that we developed can be used for measuring adhesion forces between various other proteins and substrates of interest (Chapter 4). Finally, with the development of proteomics instruments, researchers have identified some protein biomarkers, hidden within salivary fluids. These can be used for diagnostic dentistry, in a clinical setting to identify patients’ susceptibility of developing oral diseases. In addition, the delivery proteins with antimicrobial properties via toothpastes or oral rinses can have tremendous therapeutic potential for a multitude of oral diseases (Chapter 5)