Featured Research

from universities, journals, and other organizations

Iowa Study Suggests Genetics And Gender Affect Human Response To Endotoxin

Date:
September 8, 1999
Source:
University Of Iowa
Summary:
Endotoxin -- a common contaminant of agricultural dust, air pollution and household dust -- causes or exacerbates asthma and other lung problems in some, but not all, people with respiratory conditions. A recent University of Iowa Health Care study provides evidence that when it comes to healthy individuals, pulmonary responses to endotoxin can also differ markedly, yet consistently.

IOWA CITY, Iowa -- Endotoxin -- a common contaminant of agricultural dust, air pollution and household dust -- causes or exacerbates asthma and other lung problems in some, but not all, people with respiratory conditions. A recent University of Iowa Health Care study provides evidence that when it comes to healthy individuals, pulmonary responses to endotoxin can also differ markedly, yet consistently.

The study is the first to examine endotoxin response in nonsmoking, nonasthmatic and nonallergic individuals whose jobs do not put them in contact with the contaminant. The researchers found that some people had significant bronchospasm (narrowing of the airway) following slight endotoxin exposure, while others were resistant to even high dosages. Women were much more likely than men to show declined airway function after breathing even small amounts of the contaminant.

"The wide response difference in people who have no apparent predisposition to lung disease suggests a genetic cause of endotoxin susceptibility and resistance," said Joel N. Kline, M.D., UI assistant professor of internal medicine and lead investigator. "The gender-based response difference also suggests there are cellular differences. The finding may have implications for the prevention or treatment of endotoxin-associated disease in susceptible individuals."

Previous research, including studies led by David A. Schwartz, M.D., UI professor of internal medicine and a senior author for the current study, showed that the inhalation of dust containing endotoxin can cause problems for individuals with asthma or other lung conditions. A poisonous byproduct of bacterial infection or other microorganisms, endotoxin is known chemically as lipopolysaccharide. It is extremely prevalent in agricultural dust, such as that found in grain silos.

In the recent study, 72 individuals, 26 men and 46 women, inhaled incrementally increasing amounts of endotoxin. After each dose, the researchers measured the participants' pulmonary function. Kline described the highest endotoxin dosage, 40 micrograms, as the "the total amount a worker inhales during an eight-hour shift in a heavy dust-exposure site such as a grain elevator."

Eight of the participants were highly sensitive and developed "profound bronchospasm" following exposure to miniscule doses -- 6.5 micrograms -- of endotoxin. The majority of participants (53) were intermediate in their response, while 11 were hyporesponsive, meaning they showed little response even at the highest dosage. Seven of the eight highly sensitive individuals were women, while eight of the 11 hyporesponsive individuals were men, pointing to a sex-based link.

The researchers were able to reproduce the results with a sub-group of the original participant pool. In addition, to further document the response differences, the researchers studied blood cell samples taken from some of the sensitive and nonresponsive individuals. The cells from sensitive individuals had more inflammatory mediators than cells taken from the nonresponsive individuals. This cellular finding supported the physiology results of the breathing tests, Kline said.

He added that it is not entirely clear how endotoxin causes breathing problems, but the contaminant seems to cause inflammation through a "cascade" effect.

"The endotoxin causes macrophages, the most numerous inflammatory cells in the normal lung, to release mediators of inflammation such as cytokines," Kline explained. "These proteins have multiple effects including attracting other inflammatory cells."

Overall, the research adds to the "growing acceptance" that endotoxin is an important component of environmental influences on asthma and other airway obstructions, he said.

The findings were published in the July issue of the American Journal of Respiratory and Critical Care Medicine. The research team included members of the UI College of Medicine Departments of Internal Medicine and Pediatrics and the former Department of Preventive Medicine (now the UI College of Public Health) and the Veterans Affairs Medical Center in Iowa City. The study was supported by grants from the federal Department of Veterans Affairs, the National Institute of Environmental Health Sciences and the National Heart, Lung and Blood Institute.


Story Source:

The above story is based on materials provided by University Of Iowa. Note: Materials may be edited for content and length.


Cite This Page:

University Of Iowa. "Iowa Study Suggests Genetics And Gender Affect Human Response To Endotoxin." ScienceDaily. ScienceDaily, 8 September 1999. <www.sciencedaily.com/releases/1999/09/990908074434.htm>.
University Of Iowa. (1999, September 8). Iowa Study Suggests Genetics And Gender Affect Human Response To Endotoxin. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/1999/09/990908074434.htm
University Of Iowa. "Iowa Study Suggests Genetics And Gender Affect Human Response To Endotoxin." ScienceDaily. www.sciencedaily.com/releases/1999/09/990908074434.htm (accessed September 23, 2014).

Share This



More Health & Medicine News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Liberia Pleads for Help to Fight Ebola

Liberia Pleads for Help to Fight Ebola

AP (Sep. 22, 2014) Liberia's finance minister is urging the international community to quickly follow through on pledges of cash to battle Ebola. Bodies are piling up in the capital Monrovia as the nation awaits more help. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Ebola Doctor Says Border Controls Critical

Ebola Doctor Says Border Controls Critical

AP (Sep. 22, 2014) A Florida doctor who helped fight the expanding Ebola outbreak in West Africa says the disease can be stopped, but only if nations quickly step up their response and make border control a priority. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Global Ebola Aid Increasing But Critics Say It's Late

Global Ebola Aid Increasing But Critics Say It's Late

Newsy (Sep. 21, 2014) More than 100 tons of medical supplies were sent to West Africa on Saturday, but aid workers say the global response is still sluggish. Video provided by Newsy
Powered by NewsLook.com
Sierra Leone in Lockdown to Control Ebola

Sierra Leone in Lockdown to Control Ebola

AP (Sep. 21, 2014) Sierra Leone residents remained in lockdown on Saturday as part of a massive effort to confine millions of people to their homes in a bid to stem the biggest Ebola outbreak in history. (Sept. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins