Danielle: Aptamer Selection Against Immunoglobulin E with the Possibility to Treat Allergic Response

Danielle Hoyer
Nucleic Acid Aptamer Selection Against Immunoglobulin E with the Possibility to Treat Allergic Response
Full Proposal can be found here

Progress Report 1 can be found here

Progress Report 2 can be found here.

Final Report can be found here

            Seasonal allergies affect an estimated 40 million people in the United States (CDC 2003) and symptoms range from manageable in day-to-day life to life threatening if unprepared. Immunoglobulin E (IgE) is an antibody found in humans that plays a large role in allergic response. This allergic response includes IgE also is involved in other allergies such as latex, animals and food. For the purposes of this research project, the application towards seasonal allergies will be the focus. Currently there are many over the counter and prescription methods to prevent the symptoms of allergies, but these all work at either decreasing symptoms after their onset or desensitizing one to the effects of an allergen and neither are 100% effective.
The most effective method of treating allergies would be to treat further upstream at the receptor site. This would make the treatment usable for all different allergy reactions that are associated with IgE and its receptors.  An aptamer that binds to IgE prior to exposure to the allergen could disable the cascade of events that culminate in the varying degrees of symptoms. The ideal aptamer would bind to the FC region of IgE so it would be universal to all allergens. This aptamer could either bind to IgE could inhibit the allergens from binding or deliver a death message to the IgE, thus eliminating the allergic response entirely.
Specific Aim 1: Identify an RNA aptamer against IgE, specifically the FC (non-variable) region of IgE. The method for discovering said aptamer is through a series of steps otherwise known as SELEX. The precise methods of selection are detailed in the Experimental Design, Methods and Materials section.
Specific Aim 2: Develop an aptamer therapeutic against allergies. Depending on the nature of the previously developed aptamer it would take effect after the IgE has bound to the mast cell, but it would prevent an allergen from binding to IgE (See Figure 1). The aptamer may inhibit the binding of allergens to the IgE, or the more likely method would be to attach a death signal to the aptamer, which would cause the bond between IgE and its receptor on the mast cell to break.

The Human IgE used in the subsequent experiments will be obtained from MyBioSource, their contact number is 1-888-627-0165 and fax number is 1-858-633-0166. The catalog number is MBS318211. The unit price is $500.00 for 100 mg. By using a low protein to RNA ratio (200 pmols of antibody per round) this amount can last for at least six rounds of selection, more if the stringency of selection is increased and less is used per round. This will make the price per round of selection approximately $84.00. 


“CDC Fast Facts A-Z,” Vital Health Statistics, 2003
Pettipher, R., Hansel, T. T., & Armer, R. (2007). Antagonism of the prostaglandin D2 receptors

            DP1 and CRTH2 as an approach to treat allergic diseases. Nature Reviews Drug

            Discovery , 6, 313-325.


Ankita B. said...

Very cool! Allergies are a big deal, especially around Austin. Question though, is there a possibility that an aptamer, instead of inhibiting, actually activates the site?

Gwen Stovall said...

Dear Danielle,
Here are a few thoughts:
well, we didn't get very far ...

so - let's try to see if we can buy Human IgE Fc-region (only). Please continue searching. if you can't locate a vendor, then we need to come up w/ back-up plans ...
(1) select against IgE w/ variable region & see what we find. Maybe we'll luck out & select a Fc-region aptamer.
(2) ask Dr. Katy Brown (protein expert) to see if she knows where we could purchase it.
(3) mix-up the selection w/ IgE from different sources to vary the variable regions (love it!), while maintaining the Fc region.
(4) learn about antibodies

Let's meet again. Please sign-up for another meeting.


Gwen Stovall said...

Dear Danielle,
Alright - let's try this again. This time, I'll actually read your abstract & we'll wait to meet again to discuss the purchase your target (Fc only or IgE?) ...

1. title - make more positive ... get rid of "possibilty". Reword title like you've already developed this.
2. remove "otherwise known as" from the 1st paragraph. Remember, this is a "dense" abstract.
3. ck capitalization of mast cell & basophils
4. put the citation # inside the punctuation
5. consider reorg ... introduce problem, narrow in on main culprit of prob, & then offer an aptamer sol'n
6. only include details that support your story in the abstract (elaboration may occur in the introduction)
7. get rid of if & might ...no weak words
8. specific aim #1 - identify an IgE (or Fc) aptamer
9. specific aim #2 - develop an aptamer therapeutic
10. budget - include amount or ug of target, include molecular weight, & include the cost per a round.
11. review reference #1 - does it have a page number? is all the info there?

Looks good! We'll meet again tomorrow to hopefully purchase your target!

Danielle Hoyer said...

Ankita - To answer your question, To my knowledge, no I do not think it would be able to activate it, however I have a limited knowledge about the biology of antibodies. It is my understanding that this variable region is very specific to a particular antigen (in this case it would be an allergen that causes the reaction).

What I am hoping to do throughout the process of my selection is to find something that will bind to the Fc region of the IgE and not the variable region, because we definitely don't want to select for something that is variable. The current method we have chosen is to order a full polyclonal IgE, so that there are multiple clones of IgE in the sample, not a monoclonal sample which would all have the same variable region. A better method would be to have just the Fc region in the selection process but due to limited budget its not feasible for us to procure that right now.