Youna Choi and Dr. Eric Wilson, Microbiology and Molecualr Biology
Introduction
Most antigens (foreign substances) enter an organism via mucosal surfaces. Thus, understanding the mechanisms involved in immune protection at these surfaces is of paramount importance. Immune responses are highly dependent on homing mechanisms responsible for directing lymphocyte (white blood cell) migration and accumulation at target tissues. Estrogen control of lymphocyte homing within the uterus has recently been established (2).
Chemokines are soluble signaling molecules that direct the migration of cells to distinct tissues. These proteins are a crucial component of lymphocyte homing mechanisms. CCL28 is an indispensible regulator of IgA antibody secreting cell (ASC) accumulation at mucosal surfaces (1). Recent
Figure 1: Schematic representation of CCL28 and lymphocyte homing.
Estrogen is a vital hormone of the estrus cycle. The murine estrus cycle is composed of four different stages: proestrus, estrus, metestrus, and diestrus. Estrogen is highest at proestrus, and lowest at diestrus. These series of experiments show that vaccine administration during proestrus evokes the strongest immune response, (both short and longterm,) in the uterus and large intestine. By further elucidating the effects of estrogen control on lymphocyte homing at mucosal surfaces, we will gain valuable insight into how the immune system is regulated. These findings contribute to the aim of targeting immune responses to specific tissues.
Methodology
In mice, the estrus cycle lasts from 4- 6 days. Proestrus, estrus, and metestrus each last 24 hours; while, diestrus persists from 24-48 hours. The determination of stages in estrus of murine samples was performed with cytological staining of vaginal washes. To test my hypothesis, I determined the influence of estrogen control on long-term immunity, and whether or not these effects are seen throughout other mucosal tissues. In these experiments, I immunized two groups of mice intranasally twice at two week intervals with 20 micrograms of CT. The first group of mice were immunized during proestrus (high estrogen) and the second group at diestrus (low estrogen). Serum, uterine, and intestinal tissue were harvested 24 hours post the 2nd CT administration. CT specific IgA antibody (Ab) levels were quantified via ELISA assay; and, CCL28 mRNA (messenger ribonucleic acid) were quantified through real-time quantitative polymerase chain reactions.
Figure 2: Cytological Staining to Determine Stages in Estrus. Proestrus- Maximum estrogen expression. Estrus- Moderate estrogen expression . Metestrus- Decreased estrogen expression. Diestrus- Least amount of estrogen expression.
Results
Figure 3: CCL28 mRNA Expression Post 2nd CT administration. Vaccine administration during proestrus (high estrogen expression) evoked the strongest immune response in the uterus and large intestine.
Conclusion
These data suggest that IgA ASC homing to the uterus and large intestine is directed via estrogen control. CCL28 expression in the uterus and large intestine is upregulated in the presence of estrogen. Immune responses at target tissues can be selected for upon further elucidating cross talk mechanisms between the endocrine and immune systems.
References
- Brent, J., Butcher, E., Kenneth, Y., Kunkel, E., Lazarus, N., Wilson, E. (2003). A common mucosal chemokine (mucosae-associated epithelial chemokine/ccl28) selectively attracts IgA plasmablasts. The Journal of Immunology, 170: 3799-3805.
- Cha, H., Chang, S., Cuburu, N., Kim, E., Kim, S., Ko, H., Kweon, M., Ryu, S., Seo, S. (2011). Mucosaassociated epithelial chemokine/CCL28 expression in the uterus attracts CCR10+ IgA plasma cells following mucosal vaccination via estrogen control. The Journal of Immunology, 187(6), 3044-3052.