Photos of cities darkened by pollution are becoming evermore common.
These same cities are seeing a rise in cases of asthma and other
respiratory ailments, marking a relationship between pollution and
Nanoscopic particulates polluting the air enter the lungs
to cause the allergic reactions. Which immune-related events in the lung
lead to this response, however, are unclear.
‘Particulates kill macrophages, which then go on to release interleukin-1α (IL-1α). This triggers a series of events that causes respiratory illnesses.’
Scientists at the Immunology Frontier Research Center (IFReC) at
Osaka University, Japan have pinpointed a specific molecular events that
could explain allergic reactions to air pollution. These findings
provide a new therapeutic candidate to treat asthma and related
"We found that particulates kill macrophages, which then go on to
release interleukin-1α (IL-1α)", explains Etsushi Kuroda, who
first-authored a new study in Immunity
that indicates IL-1α
triggers a series of events that causes respiratory illnesses. The
release of IL-1α in mice primed the lungs for inflammation when the mice
were later exposed to an allergen. Kuroda added, "Particulates that did
not kill macrophages did not cause an allergic reaction."
However, the vulnerability of macrophages to particulates remains
unclear, which is why understanding the events following IL-1α secretion
may be key to prevention and treatment.
"IL-1α secretion was followed by the formation of iBALTs. iBALTs are
frequently found in infected or inflamed lungs and in patients with
asthma," said Osaka University Professor Ken J. Ishii, who led the
study. The increase in iBALTs led to an increase in IgE antibodies,
which intensified the immune response. On the other hand, mutant mice
that were insensitive to IL-1α did not produce iBALTs and reduced IgE
The presence of iBALTs would suggest that a human population could
remain susceptible to high levels of asthma attacks even on clear days,
as the iBALTs could form on days of high pollution, but the patient
could then be exposed to the allergen much later.
This finding suggested that iBALTs could prime the lungs to an
allergic reaction, which is why Ishii believes that iBALTs could make a
promising therapeutic target to combat the rise of respiratory illnesses
associated with air pollution. But first, he said, "we must identify
the molecular signals and key chemicals that form these iBALTs."