Gabriel Padilla conducted an undergraduate research experiment to assess the interaction between CD4+ T cells and the nematode parasite H. bakeri. He incubated CD4+ T cells alone, H. bakeri alone, and both together, and measured T cell viability, H. bakeri egg output, and worm motility. He found no significant differences between groups. Further research is needed to better understand molecular interactions and develop new drugs to treat parasites and regulate the immune system.

1.  
By Gabriel Padilla
CSUSM Biology Major

2.  My name is Gabriel Padilla, and I am a junior Biology major
at California State University San Marcos. While attending
CSUSM, I have been lucky enough to get involved in
undergraduate research. I was given the opportunity to
research, design, conduct, and present my own scientific
experiment. It has been a wonderful and rewarding
opportunity, and I am excited to share it with you!

3.  Helminths, nematode parasites, are a substantial cause
of morbidity and disease.
 It is estimated that over one billion people in the world
are infected by these worms.
 Visit the CDC's website to learn more about helminths

4.  T Helper Cell response
o CD4+ T cells recruit other cells and damage the parasite by
secreting cytokines such as:
• Interleukin-4, Interleukin-5, Interleukin-9, Interleukin-13,
Transforming Growth Factor-β
• Click here to learn more about the human immune system

5.  May damage and/or inhibit T cell function
 Can regulate and even suppress the host immune system
 An exciting area of new research, and can treat
inflammatory and/or autoimmune diseases.
Nematode
parasite
Excretory/Secretory
Product

6.  H. bakeri is a nematode and a mouse parasite.
 It is a good model for human hookworm infection
 H. bakeri produces excretory/secretory products.

7. 1. I wanted to assess if the presence of live H. bakeri
worms affects CD4+ T cell viability.
2. I wanted to assess if the presence of CD4+ T cells
affects female H. bakeri motility and reproduction.

8.  Experimental Groups:
o CD4+ T cells only (n = 4 wells)
o H. bakeri worms only (n = 4 wells)
o H. bakeri + CD4+ T cells (n = 4 wells)
o The T cells by themselves and the H. bakeri by themselves are
“control groups” so I can compare them to the H. bakeri
combined with T cells to look for differences.
 I Isolated mouse CD4+ T cells using sterile techniques;
placed in cell culture media in a 48-well plate
 I Removed H. bakeri worms from mouse small intestine;
placed in same 48-well plate
 24h incubation at 37°C in 3%O2:5% CO2:92% N gas
mixture

10.  After 24 hour incubation, the following dependent variables were
measured:
CD4+ T cell viability
• Trypan Blue exclusion
In-vitro H. bakeri egg output
• I counted the number of eggs present with a dissection
microscope
H. bakeri worm motility
• I looked at the worms under a microscope and scored them
with my 0-4 motility scoring scale
• 4- spontaneous full body movement
• 3- spontaneous head and tail movement
• 2- full body movement after probing
• 1- head and tail movement after probing
• 0- No movement after probing

11.  CD4+ T cell viability will not be affected by the presence
of H. bakeri.
o H. bakeri excretory/secretory products should suppress T cell
function, but not kill T cells.
• This is because the parasites want to exploit their hosts for living. If
they kill their hosts, then the parasites will die too.

12. Live: t=1.2, p= 0.24, DF = 54;
Dead: t=0.1, p=0.92, DF=54
H. bakeri with
CD4+T cells
CD4+T cells ONLY
Live Cells Dead Cells
Average#ofCD4+Tcells
Treatment Group

13. H. bakeri will have decreased motility and
produce fewer eggs in vitro.
o This is because mouse CD4+ T cells secrete
cytokines which can damage the worms.

14. t= 1.12, p=0.27, DF=56
H. bakeri H. bakeri and
CD4+ T cellsTreatment

15. H. bakeri H. bakeri and
CD4+ T cells
Treatment
t= 0.65, p= 0.51, DF= 56

16.  Maybe ↑ Worm Excretory/Secretory products
= T cell inhibition.
 Maybe Cytokines produced by CD4+T cells are
ineffective at damaging parasites
Maybe the CD4+T cells need the presence of other immune cells to
damage the parasites.
 Not enough CD4+ T cells or parasites in culture
Maybe I needed to add more CD4+T cells in the wells, or more than one
parasite in the wells.

17.  1.) By learning more about the molecular and cellular
interactions between host immune cells and parasites
New medications can be developed to expel the
parasites.
 2.)Helminth excretory/secretory products have
immunoregulatory capabilities.
o Current clinical trials use whole worms.
o Excretory/secretory products may have fewer side effects.
o Hopefully we will soon be able to extract these excretory
secretory products to use them to treat autoimmune diseases
such as Inflammatory Bowel Disease, Asthma, Arthritis, and
even Type 1 Diabetes!

18.  Dr. Deborah Kristan
 Samantha Lang
 The RISE Program
 Students in Dr. Kristan’s lab

19.  Behnke, J.M., Menge, D.M. and Noyes, H. (2009). Heligmosomoides bakeri: a model for
exploring the biology and genetics of resistance to chronic gastrointestinal nematode
infections. Parasitology 136, 1565-1580.
 Brooker, S. (2010). Estimating the global distribution and disease burden of intestinal
nematode infections: Adding up the numbers – A review. Int. J. Parasitol. 10, 1137-1144.
 Hotez, P., Brindley, P.J., Bethony, J.M., King, C.H., Pearce EJ, Jacobson J (2008). Helminth
infections: the great neglected tropical diseases. J Clin Invest 118, 1311–1321.
 Maizels, R.M., Hewitson, J.P., Murray, J., Harcus, Y.M., Dayer, B., Filbey, K.J., Grainger, J.R.,
McSorley, H.J., Reynolds, L.A., Smith, K.A. (2012). Immune modulation and modulators in
Heligmosomoides polygyrus infection. Exp. Parasitol. 132, 76-89
 McSorley, H.J., Hewitson, J.P., Maizels, R.M. (2013). Immunomodulation by helminth
parasites: Defining mechanisms and mediators. Int. J. Parasitol.
 Navarro, S., Ferreira, I., Loukas, A. (2013). The hookworm pharmacopoeia for inflammatory
diseases. Int J. Parasitol. 43, 225-231.
 http://babayan.bio.ed.ac.uk/index.html
 http://www.nobelprize.org/educational/medicine/immunity//immune-detail.html
 http://www.noh-sign.net/serological_plates.htm
 http://www.cdc.gov/parasites/sth/