Toll-like receptor expression in the human nasopharyngeal tonsil (adenoid) and palantine tonsils: a preliminary report.

OBJECTIVE: The Waldeyer's ring, comprised of the nasopharyngeal tonsil (adenoid), the paired tubal tonsils, the paired palantine tonsils, and the lingual tonsil, is arranged in a circular orientation around the wall of the throat. This orientation allows direct contact between the tissues of the Waldeyer's ring and inhaled or ingested material, which may contain potential antigenic substances. Previous studies involving the tissues of the Waldeyer's ring have been focused on the adaptive immune system, with little consideration toward the innate immune system. Since studies have demonstrated that the adenoids and tonsils are capable of producing proinflammatory cytokines, we postulate that toll-like receptors (TLRs), which recognize components of pathogenic organisms, may be involved in the immune response in these tissues. TLRs are innate pattern recognition receptors, which produce proinflammatory cytokines and chemokines upon ligation. In this pilot study, we address expression of TLRs, which are vital components of the innate immune system, in adenoid and tonsil tissue. METHODS: To determine whether TLRs are expressed in the human adenoid and palantine tonsils, we utilized endpoint RT-PCR and real time RT-PCR. Endpoint PCR was performed on all tissue obtained from adenotonsillectomy patients. Real time RT-PCR was performed only on adenoid tissue. RESULTS: All of the ten TLRs examined are expressed in the adenoid and tonsil tissue with varying band intensities. TLR3, TLR7, TLR8, and TLR9 expression is highly variable between patients. CONCLUSIONS: TLRs are expressed in human adenoid and tonsil tissue, and may play a vital role in the immunological outcomes of these tissues.

Human endometrial epithelial cells cyclically express Toll-like receptor 3 (TLR3) and exhibit TLR3-dependent responses to dsRNA.

Toll-like receptor 3 (TLR3) responds to dsRNA, a product of most viral life cycles, and initiates production of proinflammatory and antiviral cytokines. The role of TLR3 in human mucosal immunity of the endometrium has not been examined. The effects of TLR3 ligation in endometrial epithelium could be significant as the endometrium is a significant site for viral entry and infection. Additionally, the cytokine milieu plays an essential role in normal functions of the endometrium such as uterine cycle progression, epithelial proliferation and shedding, and embryo implantation. In this study, we demonstrated cycle dependent expression of functional TLR3 in primary endometrial epithelial tissue and expression of intracellular TLR3 in human endometrial epithelial cell lines. We established that stimulation of TLR3-positive cell lines and primary human endometrial epithelial cells with dsRNA leads to TLR3-dependent expression of interleukin (IL)-6, IL-8, interferon (IFN)-inducible protein 10, RANTES, and IFN-beta. These results indicate that the cytokine profile of human endometrial epithelial cells can be modified through TLR3 stimulation. Our findings suggest that TLR3 is involved in the immune responses of endometrial epithelial cells after exposure to dsRNA and has the potential to alter the cytokine milieu and influence the outcome and consequences of infection.

17Beta-estradiol suppresses TLR3-induced cytokine and chemokine production in endometrial epithelial cells.

BACKGROUND: The human endometrium is an important site for contact between the host and pathogens ascending the reproductive tract, and thus plays an important role in female reproductive tract immunity. Previous work in our laboratory has suggested that Toll-like receptors (TLRs) are involved in endometrial epithelial recognition of pathogens and that ligation of endometrial TLRs results in the production of cytokines and chemokines important for both immune and reproductive functions of the endometrium. We have also demonstrated cyclic regulation of TLR3 mRNA and protein expression in human endometrium, suggesting that steroid hormones might play a role in the expression and function of TLR3. In this study, the effects of 17beta-estradiol (E2) and progesterone (P) on TLR3 expression and function in endometrial cell lines were investigated. METHODS: Endometrial epithelial cell lines were cultured and examined for the presence of TLR3 and hormone receptors by endpoint RT-PCR. For hormonal studies, cells were pre-treated with ethanol vehicle, 10(-8) M E2, and/or 10(-7) M P. For antagonist assays, cells were treated with the ER antagonist, ICI 182, 780, or the PR antagonist, RU486, for two hours prior to treatment with hormones. Following hormone or hormone/antagonist pre-treatment, cells were stimulated with vehicle, the synthetic TLR3 ligand, polyinosinic-polycytidylic acid (Poly I:C), a negative dsDNA control, or a positive control. Cytokine and chemokine production post-stimulation was measured by ELISA. The effects of E2 and P on TLR3 mRNA and protein expression were measured using Real Time RT-PCR and FACS analysis, respectively. RESULTS: Stimulation of TLR3-expressing cells with the synthetic TLR3 ligand, Poly I:C, resulted in the production of cytokines and chemokines important for endometrial function and regulation. Suppression of Poly I:C-induced cytokine and chemokine production by cells treated with 10(-8) M E2, but not cells treated with 10(-7) M P, was observed in endometrial epithelial cell lines expressing TLR3 and estrogen receptor alpha (ERalpha). The effects of E2 were not observed on cells which did not express ERalpha or in cells pre-treated with the ER antagonist, ICI 182, 780. Treatment with E2 did not affect TLR3 mRNA or protein expression. However, treatment with E2 did suppress cytokine and chemokine production resulting from TLR3 stimulation with Poly I:C, suggesting that E2 modulates TLR3 function. CONCLUSION: The data presented in this study are the first indication that E2 can markedly alter the innate immune response to dsRNA, providing a previously unreported process by which E2 can alter immune responses.