Wild vs. Lab Rodent Comparison Supports Hygiene Hypothesis

[Guest guest]

Had to post this even though I think it's a bunch of bunk! I was

raised on a farm and spent many

hours shoveling manure, handling farm animals etc. There was NOTHING

hygienic about my life!

Lab Rodent Comparison Supports Hygiene Hypothesis

In a study comparing wild rodents with their laboratory counterparts,

researchers at Duke University Medical Center have found evidence

that may help to explain why people in industrialized societies that

greatly stress hygiene have higher rates of allergy and autoimmune

diseases than do people in less developed societies in which hygiene

is harder to achieve or considered less critical.

The prevailing hypothesis concerning the development of allergy and

probably autoimmune disease is the " hygiene hypothesis, " which states

that people in " hygienic " societies have higher rates of allergy and

perhaps autoimmune disease because they - and hence their immune

systems - have not been as challenged during everyday life by the

host of microbes commonly found in the environment.

The study suggests that an overly hygienic environment could

simultaneously increase the tendency to have allergic reactions and

the tendency to acquire autoimmune disease, despite the fact that

these two reactions represent two different types of immune responses.

The researchers added that their experimental model, which compares

specific immune system responses of wild rodents to laboratory

rodents, could open up a new approach to studying human disease and

allergies that complements traditional scientific studies.

" Laboratory rodents live in a virtually germ- and parasite-free

environment, and they receive extensive medical care - conditions

that are comparable to what humans living in Westernized, hygienic

societies experience, " said , Ph.D., an assistant

professor of experimental surgery and senior member of the study

team. " On the other hand, rodents living in the wild are exposed to a

wide variety of microbes and parasites, much like humans living in

societies without modern health care and where hygiene is harder to

maintain. "

The researchers published their results early on-line in the

Scandinavian Journal of Immunology. The research was supported by the

National Institutes of Health, the Duke University School of Medicine

and the Fannie E. Rippel Foundation.

Up to 50 million Americans are estimated to suffer from allergies,

and another 8 million have some form of autoimmune disorder, which

occurs when an overactive immune system attacks tissues in the body.

Examples of autoimmune disorders include lupus, insulin-dependant

diabetes, rheumatoid arthritis and scleroderma.

" The most commonly accepted explanation for this high incidence of

allergy and perhaps autoimmune disease is the hygiene hypothesis, "

said. But this hypothesis has not been thoroughly tested in

animal studies, he said, and the few studies conducted have focused

on specific pathogens or parasites.

The Duke researchers decided to study the hypothesis by comparing the

immune systems of wild house mice and common rats to laboratory mice

and rats. The strength of this model, said, is that it takes

into account the totality of the animals living in their natural

environment.

Specifically, the team focused the animals' production of various

antibodies, known as immunoglobulins, either associated with

autoimmune disease or associated with allergy. When an animal

encounters a foreign invader, or antigen, its immune system kicks

into action by producing antibodies that bind to the invader and

destroy it.

Of the many classes of immunoglobulins (Ig), the IgG type is often

involved in autoimmune disease, while the IgE type is likely a key

defender against parasites and has been implicated in allergic

reactions in humans, said.

For their experiments, the researchers trapped wild rats in rural and

urban settings in North Carolina and trapped wild mice in Wisconsin.

They then measured the levels of antibodies in the blood of the wild

rodents and compared the levels to those observed in mice and rats

housed in Duke animal facilities.

All of the wild rodents had higher levels of IgG and IgE, with the

IgE showing the most pronounced difference, said.

Additionally, the wild rodents had higher levels of a particular type

of IgG called polyreactive, autoreactive IgG, which is associated

with autoimmune disease in hygienic humans and rodents. However, the

increased levels of these antibodies did not presumably cause

untoward reactions in the wild rodents, said.

That wild rodents had higher levels of IgE was not unexpected, he

added, since wild rodents would likely have encountered parasites

that activated the production of antibodies as protection. However,

the production of polyreactive, autoreactive IgG by the wild rodents

was unexpected: Polyreactive, autoreactive antibodies are always

found to be a type of IgM, a different type of antibody than IgG,

although all previous studies have focused on hygienic populations.

" These results appear to demonstrate that the environment has

profound effects on the production of IgE and autoreactive IgG, "

said. " While the production of these two antibody types lead

to autoimmune disease and allergy, respectively, in the laboratory

animals, their production seemed to represent a nonpathogenic,

protective response to the environment by the wild rodents.

" We would expect that the targets of the autoreactive IgG and IgE in

the 'hygienic' laboratory rodents would be substantially different

from the targets of the same antibodies in the wild animals, " he said.

In the wild animals, the autoreactive IgG likely bind to

environmental antigens and therefore do not have deleterious effects,

said.

" However, autoreactive IgG in hygienic animals can bind avidly to the

body's own cells, which can lead to autoimmune disease, " he said. " In

a parallel fashion, the IgE in the wild animals is protective because

the antibodies bind to parasite antigens, while the same antibodies

in laboratory animals would bind to abundant but harmless

environmental antigens, leading to allergies to those antigens. "

" These results are consistent with the idea that animals without

access to modern medicine have high levels of autoimmune-like and

allergic-like immune responses that represent appropriate responses

to unknown factors in their environment, " he said.

Although this study suggests that the environment plays an important

role in how the immune systems in animals develop, genetics is likely

to be involved as well, said. He now is planning additional

studies to help decipher the full role of genetics.

Also, his group is planning further studies of the hygiene

hypothesis, using the new rodent model to examine other factors that

may be contributing to the higher rates of allergy and autoimmune

diseases of humans in industrialized societies, such as lack of

exercise, increased mental stress and the consumption of processed food.

[Guest guest]

a, I guess it's a good proof that anything can be published. All you

have to do is write something that sounds good and call it a " Hypothesis " . I

wonder how much of a bonus a person gets for being published. Maybe we've

been looking for the wrong type of work....

Dennis- from the farm, also

[ ] Wild vs. Lab Rodent Comparison Supports Hygiene

Hypothesis

> Had to post this even though I think it's a bunch of bunk! I was

> raised on a farm and spent many

> hours shoveling manure, handling farm animals etc. There was NOTHING

> hygienic about my life!

>

>

>

>

>

> Lab Rodent Comparison Supports Hygiene Hypothesis

>

> In a study comparing wild rodents with their laboratory counterparts,

> researchers at Duke University Medical Center have found evidence

> that may help to explain why people in industrialized societies that

> greatly stress hygiene have higher rates of allergy and autoimmune

> diseases than do people in less developed societies in which hygiene

> is harder to achieve or considered less critical.

>

> The prevailing hypothesis concerning the development of allergy and

> probably autoimmune disease is the " hygiene hypothesis, " which states

> that people in " hygienic " societies have higher rates of allergy and

> perhaps autoimmune disease because they - and hence their immune

> systems - have not been as challenged during everyday life by the

> host of microbes commonly found in the environment.

>

> The study suggests that an overly hygienic environment could

> simultaneously increase the tendency to have allergic reactions and

> the tendency to acquire autoimmune disease, despite the fact that

> these two reactions represent two different types of immune responses.

>

> The researchers added that their experimental model, which compares

> specific immune system responses of wild rodents to laboratory

> rodents, could open up a new approach to studying human disease and

> allergies that complements traditional scientific studies.

>

> " Laboratory rodents live in a virtually germ- and parasite-free

> environment, and they receive extensive medical care - conditions

> that are comparable to what humans living in Westernized, hygienic

> societies experience, " said , Ph.D., an assistant

> professor of experimental surgery and senior member of the study

> team. " On the other hand, rodents living in the wild are exposed to a

> wide variety of microbes and parasites, much like humans living in

> societies without modern health care and where hygiene is harder to

> maintain. "

>

> The researchers published their results early on-line in the

> Scandinavian Journal of Immunology. The research was supported by the

> National Institutes of Health, the Duke University School of Medicine

> and the Fannie E. Rippel Foundation.

>

> Up to 50 million Americans are estimated to suffer from allergies,

> and another 8 million have some form of autoimmune disorder, which

> occurs when an overactive immune system attacks tissues in the body.

> Examples of autoimmune disorders include lupus, insulin-dependant

> diabetes, rheumatoid arthritis and scleroderma.

>

> " The most commonly accepted explanation for this high incidence of

> allergy and perhaps autoimmune disease is the hygiene hypothesis, "

> said. But this hypothesis has not been thoroughly tested in

> animal studies, he said, and the few studies conducted have focused

> on specific pathogens or parasites.

>

> The Duke researchers decided to study the hypothesis by comparing the

> immune systems of wild house mice and common rats to laboratory mice

> and rats. The strength of this model, said, is that it takes

> into account the totality of the animals living in their natural

> environment.

>

> Specifically, the team focused the animals' production of various

> antibodies, known as immunoglobulins, either associated with

> autoimmune disease or associated with allergy. When an animal

> encounters a foreign invader, or antigen, its immune system kicks

> into action by producing antibodies that bind to the invader and

> destroy it.

>

> Of the many classes of immunoglobulins (Ig), the IgG type is often

> involved in autoimmune disease, while the IgE type is likely a key

> defender against parasites and has been implicated in allergic

> reactions in humans, said.

>

> For their experiments, the researchers trapped wild rats in rural and

> urban settings in North Carolina and trapped wild mice in Wisconsin.

> They then measured the levels of antibodies in the blood of the wild

> rodents and compared the levels to those observed in mice and rats

> housed in Duke animal facilities.

>

> All of the wild rodents had higher levels of IgG and IgE, with the

> IgE showing the most pronounced difference, said.

> Additionally, the wild rodents had higher levels of a particular type

> of IgG called polyreactive, autoreactive IgG, which is associated

> with autoimmune disease in hygienic humans and rodents. However, the

> increased levels of these antibodies did not presumably cause

> untoward reactions in the wild rodents, said.

>

> That wild rodents had higher levels of IgE was not unexpected, he

> added, since wild rodents would likely have encountered parasites

> that activated the production of antibodies as protection. However,

> the production of polyreactive, autoreactive IgG by the wild rodents

> was unexpected: Polyreactive, autoreactive antibodies are always

> found to be a type of IgM, a different type of antibody than IgG,

> although all previous studies have focused on hygienic populations.

>

> " These results appear to demonstrate that the environment has

> profound effects on the production of IgE and autoreactive IgG, "

> said. " While the production of these two antibody types lead

> to autoimmune disease and allergy, respectively, in the laboratory

> animals, their production seemed to represent a nonpathogenic,

> protective response to the environment by the wild rodents.

>

> " We would expect that the targets of the autoreactive IgG and IgE in

> the 'hygienic' laboratory rodents would be substantially different

> from the targets of the same antibodies in the wild animals, " he said.

>

> In the wild animals, the autoreactive IgG likely bind to

> environmental antigens and therefore do not have deleterious effects,

> said.

>

> " However, autoreactive IgG in hygienic animals can bind avidly to the

> body's own cells, which can lead to autoimmune disease, " he said. " In

> a parallel fashion, the IgE in the wild animals is protective because

> the antibodies bind to parasite antigens, while the same antibodies

> in laboratory animals would bind to abundant but harmless

> environmental antigens, leading to allergies to those antigens. "

>

> " These results are consistent with the idea that animals without

> access to modern medicine have high levels of autoimmune-like and

> allergic-like immune responses that represent appropriate responses

> to unknown factors in their environment, " he said.

>

> Although this study suggests that the environment plays an important

> role in how the immune systems in animals develop, genetics is likely

> to be involved as well, said. He now is planning additional

> studies to help decipher the full role of genetics.

>

> Also, his group is planning further studies of the hygiene

> hypothesis, using the new rodent model to examine other factors that

> may be contributing to the higher rates of allergy and autoimmune

> diseases of humans in industrialized societies, such as lack of

> exercise, increased mental stress and the consumption of processed food.

>

>