Team:UC Davis/Project

From 2009.igem.org

(Difference between revisions)
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</p>
</p>
<p><o:p></o:p><span style=""><big><span
<p><o:p></o:p><span style=""><big><span
-
style="font-weight: bold; font-style: italic;">What happens in Celiac
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style="font-weight: bold; font-style: italic;">What happens in the small intestine of people with celiac
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disease small
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disease?</span></big><o:p></o:p></span></p>
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intestine?</span></big><o:p></o:p></span></p>
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<span style="font-weight: bold;"></span>
<span style="font-weight: bold;"></span>
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<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; The brush border membrane in
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<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; The brush border characteristic to people with celiac disease allows large molecules such as gliadin to go straight
-
the small intestine of people suffering from
+
-
Celiac Disease allows large molecules such as gliadin to go straight
+
into the
into the
blood stream without directing them through the transcellular route.
blood stream without directing them through the transcellular route.
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gliadin passes through, Antigen Presenting Cells (APCs) recognize
gliadin passes through, Antigen Presenting Cells (APCs) recognize
gliadin as a
gliadin as a
-
foreign object and will attack. This immune response results in
+
foreign object and attack. This immune response results in the inflammation of
-
inflammation of
+
the surface of the intestine with loss of the normal cells required for
the surface of the intestine with loss of the normal cells required for
absorption of sugars, protein, and fat from the diet. <o:p></o:p></p>
absorption of sugars, protein, and fat from the diet. <o:p></o:p></p>
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<p>The immune response not only causes abdominal pain, bloating,
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<p>In addition to the array of symtpoms illustrated above, the immune response may also damage intestinal villi, which are important
-
diarrhea and
+
-
weight loss it may also damage intestinal villi, which are important
+
for
for
absorbing nutrients. The destruction of villi eventually leads to a
absorbing nutrients. The destruction of villi eventually leads to a
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&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Currently, no cure has been found
&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Currently, no cure has been found
for this illness. The only way to avoid
for this illness. The only way to avoid
-
some of celiac disease’s symptoms is by adopting a gluten free diet
+
the symptoms of celiac disease is by adopting a gluten-free diet
(14, 12,
(14, 12,
-
and 11). However, you are more likely to find gluten in your everyday
+
and 11). However, you are highly likely to find gluten in your everyday
-
diet, and
+
diet (in foods such as grains), and
people with celiac disease must purchase gluten-free substances from
people with celiac disease must purchase gluten-free substances from
specialized grocery stores. "Oral supplementation with prolyl
specialized grocery stores. "Oral supplementation with prolyl
oligopeptidases that can digest and detoxify gluten has therefore been
oligopeptidases that can digest and detoxify gluten has therefore been
proposed
proposed
-
as a potential therapeutic approach."(8). However, enzymes studied
+
as a potential therapeutic approach."(8) However, enzymes studied
earlier
earlier
-
were not able to degrade gluten inside stomach (before it reaches small
+
were not able to degrade gluten inside the stomach (before it reaches the small
-
intestine) because they were "irreversibly inactivated by pepsin and
+
intestine), because they were "irreversibly inactivated by pepsin and
acidic pH, both present in the stomach."(8) <o:p></o:p></p>
acidic pH, both present in the stomach."(8) <o:p></o:p></p>
<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Nevertheless, over the past
<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Nevertheless, over the past
-
years, researchers have discovered an enzyme
+
years, researchers have discovered an enzyme--a newly-identified prolyl endoprotease--from <i>Aspergillus niger</i>,  
-
from <i>Aspergillus niger</i>, a newly identified prolyl endoprotease,
+
that was
that was
-
observed to "work optimally at 4-5pH and remains stable at 2pH"(8)
+
observed to "work optimally at 4-5pH and remains stable at 2pH"(8).
-
and maybe this enzyme will lead us to an alternative treatment for this
+
Perhaps this enzyme will lead us to an alternative treatment for this
-
disorder (8). Studies have shown that prolyl-endoprotease from <i>Aspergillus
+
disorder(8). Studies have shown that prolyl endoprotease from <i>A.niger</i> is able to "degrade gluten in vitro and under conditions
-
niger</i> is able to "degrade gluten in vitro and under conditions
+
similar
similar
-
to the ones present in the gastrointestinal tract." (8)&nbsp;; but due
+
to the ones present in the gastrointestinal tract." (8)&nbsp;; However, due
to
to
-
licensing restrictions we have opted not to work with this protein. <o:p></o:p></p>
+
licensing restrictions, we have opted not to work with this protein. <o:p></o:p></p>
<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Recently (year 2007), a study
<p>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; Recently (year 2007), a study
has suggested an alternative approach by
has suggested an alternative approach by
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prolyl
prolyl
endopeptidase (SC PEP from <span style="font-style: italic;">Sphingomonas
endopeptidase (SC PEP from <span style="font-style: italic;">Sphingomonas
-
capsulata</span>); with gastric
+
capsulata</span>) with gastric
activity and
activity and
-
complementary substrate specificity there is a possibility of
+
complementary substrate specificity(12). Using this method, there is a possibility of
increasing the
increasing the
-
safe threshold of ingested gluten (12). One of the advantages of this
+
safe threshold of ingested gluten(12). One of the advantages of this
“combination product is that both enzymes are active and stable in
“combination product is that both enzymes are active and stable in
stomach and
stomach and
can therefore be administered as lyophilized powders or simple capsules
can therefore be administered as lyophilized powders or simple capsules
or
or
-
tablets” (12). <o:p></o:p><br>
+
tablets”(12). <o:p></o:p><br>
<o:p></o:p></p>
<o:p></o:p></p>
<p class="MsoNormal" style="line-height: normal;"><i><span
<p class="MsoNormal" style="line-height: normal;"><i><span

Revision as of 02:03, 22 October 2009

lol

   
Project:
Celiac Disease          Current treatment           Our Approach
What is Celiac Disease?

        Celiac Disease is an autoimmune disorder that occurs inside the small intestine. When the body cannot properly digest gliadin (a component of gluten), this leads to an immune response on the surface of the small intestine (14). Different people have varying degrees of immune response such as bloating, diarrhea, and weight loss (14). An estimated one out of 133 Americans currently suffer from this disease (11). Considering the estimated 3.08 million people in America, this isn't a minor issue. In fact, it was one of our teammate's friends suffering from celiac who initially sparked our interest in designing this project.

What happens in the normal small intestine?
       
        The inside surface of the small intestine is covered with small microvilli, constituting the brush border membrane. In the normal small intestine, the brush border membrane is where polysaccharides, proteins, and fat droplets are digested into smaller parts that then get absorbed into the bloodstream.

What happens in the small intestine of people with celiac disease?

        The brush border characteristic to people with celiac disease allows large molecules such as gliadin to go straight into the blood stream without directing them through the transcellular route. Once gliadin passes through, Antigen Presenting Cells (APCs) recognize gliadin as a foreign object and attack. This immune response results in the inflammation of the surface of the intestine with loss of the normal cells required for absorption of sugars, protein, and fat from the diet.

In addition to the array of symtpoms illustrated above, the immune response may also damage intestinal villi, which are important for absorbing nutrients. The destruction of villi eventually leads to a lack of absorption of different nutrients, which can lead to malnutrition (14). Some people affected with this disorder can also suffer from autoimmune thyroid disease, autoimmune liver disease, and rheumatoid arthritis (diseases in which body immune system attacks healthy cells/tissues) (14).


Current treatments:

        Currently, no cure has been found for this illness. The only way to avoid the symptoms of celiac disease is by adopting a gluten-free diet (14, 12, and 11). However, you are highly likely to find gluten in your everyday diet (in foods such as grains), and people with celiac disease must purchase gluten-free substances from specialized grocery stores. "Oral supplementation with prolyl oligopeptidases that can digest and detoxify gluten has therefore been proposed as a potential therapeutic approach."(8) However, enzymes studied earlier were not able to degrade gluten inside the stomach (before it reaches the small intestine), because they were "irreversibly inactivated by pepsin and acidic pH, both present in the stomach."(8)

        Nevertheless, over the past years, researchers have discovered an enzyme--a newly-identified prolyl endoprotease--from Aspergillus niger, that was observed to "work optimally at 4-5pH and remains stable at 2pH"(8). Perhaps this enzyme will lead us to an alternative treatment for this disorder(8). Studies have shown that prolyl endoprotease from A.niger is able to "degrade gluten in vitro and under conditions similar to the ones present in the gastrointestinal tract." (8) ; However, due to licensing restrictions, we have opted not to work with this protein.

        Recently (year 2007), a study has suggested an alternative approach by combining a glutamine-specific endoprotease (EP-B2 from barley) and a prolyl endopeptidase (SC PEP from Sphingomonas capsulata) with gastric activity and complementary substrate specificity(12). Using this method, there is a possibility of increasing the safe threshold of ingested gluten(12). One of the advantages of this “combination product is that both enzymes are active and stable in stomach and can therefore be administered as lyophilized powders or simple capsules or tablets”(12).


Our approach:

        Gliadin induces an immune system response when it is absorbed into the blood stream through the small intestine. We plan to take advantage of this by breaking down gliadin in the stomach before it reaches the small intestine. We have developed a secretion system to release an enzyme that can break down gliadin. Also, in order to prevent our delivery system from taking residence anywhere outside of the stomach, we plan to incorporate the difference in pH between the stomach and small intestine with a pH-inducible apoptosis system. By adopting these two systems, we will create a pH-moderated secretion system.
        Unlike other suggested treatments requiring the consumption of capsules or tablets, our method of using E. coli as our delivery system is more cost- and time-efficient.


Our project is split into two parts:
1.Induced Secretion

2. Sensing pH  and inducing cell death