The effect of desert dust particles on rheological properties of saliva and mucus

Abstract

Transported desert dust particles (TDDP) are soil particles suspended in the air. Being spread all over the globe by the winds, TDDP affect animals, including humans, plants and other organisms not only in the areas of their emission. In humans, TDDP are responsible for diseases of the respiratory (e.g. asthma) and circulatory (e.g. heart failure) systems and they also act directly on the epithelium and its mucus layer after deposition in the mouth and respiratory system. The aim of the study was to determine the influence of TDDP on the rheology of mucus and saliva, and thus on their functioning. The artificial mucus and saliva, as well as Arizona TDDP, were used in experiments. The rheological properties of TDDP were determined with the use of an oscillatory rheometer, at various temperatures and in the presence of different amount of TDDP. Moreover, the diffusion time of the marker (rhodamine B) throughout mucus with desert dust particles was examined. The obtained results demonstrate that the presence of TDDP in the saliva and mucus model increases their apparent viscosity. The concentration of particles is positively correlated with the increase of viscosity. However, it has not been demonstrated that the presence of TDDP in mucus significantly influenced the diffusion of a fluorescent marker throughout the mucus. The presence of TDDP in the saliva and mucus may interfere with their moisturising function, and cause difficulties in swallowing by increasing the viscosity of mucus and saliva. Moreover, increased viscosity of mucus may cause problems with its ability to pass to the upper respiratory tracts, which may lead to a general discomfort or local inflammation.

Mechanisms underlying the health effects of desert sand dust

“…The protection and lubrication functions of mucus and saliva are closely linked to their rheological properties, which in turn are determined by chemical composition, physical parameters, health, age, sex or activity. Artifical mucus and saliva models exposed to Arizona transported desert dust particles (0.06 g/l and 6 g/l) increases viscosity in a dose dependent manner ( Penconek et al 2019 ). However the presence of particles at a concentration of 6 g/l in mucus had no significant effects on the diffusion of the fluorescent marker through the mucus layer (an indicator of changes in mucus protective properties) implying that the protective function of mucus had not been disturbed.…”

Salivary analysis: An emerging paradigm for non‐invasive healthcare diagnosis and monitoring

“…Mucus also plays a crucial role in protecting the body from harmful bacteria, viruses, and other pathogens 64 . It contains antibodies and enzymes that help to fight off infections, and it can trap and remove foreign particles, such as dust and pollen, from the respiratory tract 66 . The amount and consistency of mucus in human saliva can vary depending on a person's health status, lifestyle factors, and environmental conditions.…”

From Static to Dynamic: A Review on the Role of Mucus Heterogeneity in Particle and Microbial Transport

“…126 In addition, transported desert dust particles (TDDP) can increase mucus viscosity, which does not show any effects on particle diffusion rates. 194 When the effects of species (human vs pig) versus age (new born vs adult) are compared, the aging process has more profound effects on particle transport through the McLs mainly due to the decrease in viscosity with the increase in age. 195 The MCT is highly heterogeneous in newborn pigs due to factors including variations in submucosal gland secretions, unevenness of mucus thickness, and regional differences in mucus biophysical properties such as microrheology.…”

“…This effect cannot be revoked with polysorbate 80 (Tween) . In addition, transported desert dust particles (TDDP) can increase mucus viscosity, which does not show any effects on particle diffusion rates …”