Mumbai, Feb 13 (PTI) The Indian Institute of Technology Bombay (IIT Bombay) on Friday said its researchers have found that too much mucus can weaken the lungs' defences, which can make people more prone
to allergy attacks.
The airways to the lungs have a naturally engineered defence mechanism that gets activated when any foreign material enters the airways by secreting a fluid called mucus to trap it.
However, for millions of people living in cities like Delhi, Mumbai, Bengaluru and other metros, the rising levels of air pollution have been posing a persistent health hazard, with heavy smog-filled air causing severe respiratory issues.
In a recent study, IIT Bombay researchers have found that as mucus volume increases in response to pollution (or a foreign material) in the airways, its defence does not improve.
Instead, the study conducted by Swarnaditya Hazra and Professor Jason R Picardo, found that the increased mucus volume ends up creating narrow 'humps' that leave large patches of the airway walls completely exposed.
"This patchy landscape could explain why excessive mucus is detrimental, potentially allowing fine soot particles to penetrate deep into our systems and triggering asthma attacks," added the study.
A significant fraction of soot particles has submicron sizes, such tiny particles would deposit on the airway wall by diffusion if the wall is left exposed, explained Professor Picardo.
"Our work shows that the mucus coating, which lines the airways, becomes more patchy as its volume increases," he said.
While it might seem logical that more fluid would lead to greater coverage, the researchers found that it was not so.
"To be clear, our finding is that a more voluminous mucus film gathers into humps that are deeper but narrower, consequently, the mucus-depleted zones expand. This is indeed counterintuitive," Professor Picardo said.
For residents of high-pollution zones, this finding is more than a mathematical curiosity, it is a matter of respiratory survival.
Soot particles, common in urban environments, are often submicron in size or thousands of times thinner than a human hair and these tiny particles move through a process called diffusion, and they are highly likely to land on any exposed part of the airway wall.
When mucus becomes patchy due to its high volume, it leaves the lung walls vulnerable, the study revealed.
"Beyond the lack of coverage, excessive mucus can also lead to the physical plugging of the airways, obstructing the very air we need to survive," said Hazra.
This research also sheds light on the 'vicious cycle' of rapid-onset asthma.
When a person with asthma inhales an allergen, their body reacts by secreting more mucus and according to the IIT Bombay study, this hypersecretion causes the mucus to gather into those narrow humps, exposing more of the airway wall to the very allergens that caused the reaction in the first place.
Professor Picardo said, "This could amplify the allergic response as allergen deposition triggers mucus oversecretion and airway constriction... this in turn would result in more of the wall becoming exposed to allergens, whose subsequent deposition would amplify the allergic response."
While further work is needed to link fluid mechanics to cellular responses, the study provides a physical basis for why some asthma attacks escalate so rapidly.
Understanding how these mucus humps form and where they catch particles can help scientists to design 'designer drug particles' that land exactly where they are needed, added the study. PTI SM BNM
