[Show abstract][Hide abstract] ABSTRACT: Heterosexual human immunodeficiency virus (HIV) transmission implies the crossing of the vaginal mucosa by virions present in the semen, potentially using Langerhans cells as transporters. The recruitment of these cells in the mucosa is mediated by the chemokine macrophage inflammatory protein 3alpha (CCL20). The aim of this study was to evaluate the capacity of the semen to induce Langerhans cell recruitment via the production of CCL20 by vaginal epithelial cells.
Using a vaginal epithelium model based on the SiHa cell line and human seminal plasma, we demonstrated that semen enhanced the production of CCL20. This secretion was regulated by the nuclear factor-kappaB intracellular signalling pathway. Fractionation of the seminal plasma indicated that the secretion of CCL20 was stimulated by high molecular weight compounds present in semen. Migration assays demonstrated that secreted CCL20 was able to promote the recruitment of Langerhans cell precursors (LCps), which remain permissive to X4 and R5 HIV infection.
Our results demonstrate that epithelial cells respond to factors present in semen by secreting CCL20, leading to the enhancement of LCp recruitment. These data argue in favour of the implication of epithelial cells in the heterosexual transmission of HIV.
Full-text · Article · Jun 2006 · Human Reproduction
[Show abstract][Hide abstract] ABSTRACT: X4 and R5 HIV strains are present in the semen of men infected with HIV but R5 isolates are transmitted preferentially. The role of human epithelial cells in this selection is addressed. Three human cervical cell lines-CaSki, SiHa, and HEC1A-and normal human vaginal cells from HIV-negative donors were characterized for HIV receptor expression and incubated with X4 and R5 laboratory-adapted strains or primary isolates. The infection was assessed by detection of intracellular HIV DNA. The three cell lines were shown to express on their surface the CXCR4 and GalCer molecules, but not the CD4 and CCR5 ones. The three cell lines and normal human vaginal cells were found to be selectively permissive to X4 HIV entry; the preincubation of the cell lines with rhSDF-1 inhibited this infection. The detection of the intracellular proviral DNA in the cell lines and in normal human vaginal cells demonstrated a selective integration of X4 strains. Additional experiments showed that no extracellular RNA was detected in the supernatants of HEC1A cells infected by X4 isolates either after 18 days of culture or after incubation with PHA-stimulated PBMCs and that no transmission occurred after co-culture between infected HEC1A cells and PHA-stimulated PBMCs. These results suggest specific sequestration of X4 strains by genital epithelial cells, which could explain, at least in part, the HIV tropism selection process during sexual intercourse.
No preview · Article · Nov 2005 · Journal of Medical Virology
[Show abstract][Hide abstract] ABSTRACT: Mucosa represents the main site of pathogen/cell interactions. The two main types of cells forming the epithelial structure [epithelial cells and Langerhans cells (LC)] coordinate the first defense responses to avoid infection. To evaluate the involvement of epithelial cells in the early steps leading to a specific adaptive immune response, we have studied the interactions between vaginal epithelial and LC through the establishment of a human vaginal epithelial mucosa. We demonstrate that normal human vaginal epithelial cells constitutively secrete the chemokine macrophage inflammatory protein 3alpha/CC chemokine ligand 20 (CCL20), known to recruit LC precursors (LCps) selectively via its cognate CC chemokine receptor 6 (CCR6). This secretion is up-regulated by the proinflammatory cytokine interleukin-1beta through the nuclear factor-kappaB pathway. Similar results were obtained with the human vaginal epithelial cell line SiHa, which displays numerous homologies with normal vaginal cells. The chemotactic activity of the secreted CCL20 was demonstrated by its ability to attract LCp CCR6+. Moreover, the use of neutralizing polyclonal antibodies directed against the CCL20 molecule abolished this migration completely, suggesting that CCL20 is the main attracting factor for LCps, which is produced by the vaginal cells. These data indicate that vaginal epithelial cells play an important role in the immunological defense by attracting immune cells to the site of epithelial/pathogen contact.
Full-text · Article · Aug 2005 · Journal of Leukocyte Biology
[Show abstract][Hide abstract] ABSTRACT: Platelets are primarily involved in thrombosis and haemostasis, and they have recently been shown to have a role in innate immunity and in inflammation. We have determined the markers of innate immunity that are expressed by platelets, specifically the Toll-like receptors (TLR), originating from mixes of platelet concentrates (MPC, n = 5) between day zero and day five after blood collection. The surface membrane and intracellular expression of TLR were measured, both after and without permeabilization, using flow cytometry. We observed weak expression of TLR2, TLR4 and TLR9 on the surface of CD41(+) platelets. The expression levels of TLR4 were high (59 +/- 2.2%). Moreover, there was a significant expression of TLR2 (47.5 +/- 4.8%), TLR4 (78.8 +/- 1.3%) and TLR9 (34.2 +/- 7.5%) in the cytoplasm of CD41(+) platelets. The expression of the three receptors did not change significantly during the course of the 5 day observation period. The percentage of TLR expression is significantly modulated between activated versus non-activated platelets, both after and without permeabilization (P < 0.01). Study of the expression of TLR could increase our knowledge of the level of platelet participation during an immune reaction and inflammation. In the same way as the platelet ligand/receptor pair CD40L/CD40 is, the TLR are expressed by platelets, and could serve as a link between innate and adaptive immunity.
Full-text · Article · May 2005 · Immunology and Cell Biology
[Show abstract][Hide abstract] ABSTRACT: Malignant Langerhans cell tumor is a rare malignant proliferation of Langerhans cells, with a negative prognosis due to its dissemination throughout the body, leading to death within 1 year. This disease has to be distinguished from Langerhans cell histiocytosis. The favorable evolution of a case of Langerhans cell tumor, characterized by the absence of metastasis 18 months after its occurrence, may be due to the initial treatment, which consisted of complete and large resection of the tumor. The authors searched for abnormal dendritic cells or progenitors in the blood but found no large amounts or proliferation of CD34(+) or CD1a(+) cells at the diagnosis and 1 year later. This case report shows that malignant Langerhans cell tumor is not always a lethal disease. The condition may be related to surgical treatment and the absence of malignant cells in the blood when the diagnosis was performed.
No preview · Article · Oct 2003 · Journal of the American Academy of Dermatology
[Show abstract][Hide abstract] ABSTRACT: All three-dimensional in vitro mucosal models constructed, thus far, have only been reconstituted by epithelial cells. We have developed a reconstructed oral and vaginal epithelium that integrates Langerhans' cells (LC), the dendritic cells (DC) of malpighian epithelia. The epithelium was composed of gingival or vaginal keratinocytes seeded on a de-epidermized dermis (DED) and grown in submerged culture for 2 weeks. LC precursors, obtained after differentiation of cord blood-derived CD34+ hematopoietic progenitor cells (CD34+HPC) by granulocyte macrophage-colony stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta) and Flt3-ligand (Flt3-L), were introduced after 6-8 days of culture into the reconstituted epithelium. The in vitro reconstituted mucosal epithelium formed a multilayered, well-differentiated epithelial structure, confirmed by the immunohistochemical expression of cytokeratins 4, 6, 10, 13, 14, 16 and involucrin. LC were identified in the basal and suprabasal epithelial layers by CD1a antigen, S100 protein and Langerin/CD207 expression, and by transmission electron microscopy. Type IV collagen was expressed at the chorio-epithelial junction, and most ultrastructural features of this junction were visualized by electron microscopy. This in vitro reconstructed gingiva or vagina integrating LC represents interesting models very similar to native tissues. Because LC play an important role in the mucosal immune system, our models could be useful for conducting studies on interactions with pathogenic agents (viruses, bacteria etc.), as well as in pharmacological, toxicological and clinical research.
No preview · Article · Sep 2003 · Experimental Dermatology
[Show abstract][Hide abstract] ABSTRACT: HIV can cross the intact epithelium of genital mucosae via Langerhans cells. Fresh Langerhans cells are known to express CD4 and CCR5. The presence of CXCR4 on the surface of cultured but not freshly isolated Langerhans cells has been described. In the present study, we demonstrate that CXCR4 was expressed by fresh Langerhans cells isolated and purified from epidermis. However, the percentage of Langerhans cells expressing CXCR4 or CCR5 increased during maturation of the cells in culture, especially in the presence of exogenous granulocyte-macrophage colony-stimulating factor. To determine whether CXCR4 was functional, freshly isolated Langerhans cells were infected with HIV LAI, a T-cell-tropic strain, and p24 protein production was measured in culture supernatants. p24 production was observed when infected Langerhans cells were cocultured with SupT1 cells. However, the presence of HIV provirus DNA was evidenced within the infected Langerhans cells by nested PCR. Ultrastructural studies confirmed the formation of syncytia when Langerhans cells were cocultured with SupT1 cells. Preincubation of Langerhans cells with azidothymidine or SDF-1-alpha, a natural ligand for CXCR4, prevented infection. These data demonstrated that CXCR4 is present on the surface of Langerhans cells freshly isolated from human skin epidermis and that this expression is functional.
[Show abstract][Hide abstract] ABSTRACT: Substance P is a neurotransmitter which plays its role in the central and peripheral nervous system. However, substance P is also involved in many other phenomenons and particularly in immune cell regulation. This neurotransmitter can be found in skin, in contact with Langerhans cells. The latter are dendritic antigen-presenting cells, localized in skin and mucosae, which induce immune response. This review will focus on Langerhans cell and substance P separately, and on interactions between these two components especially in the case of Langerhans cell infection by human immunodeficiency virus.
No preview · Article · Jan 2001 · Nouvelles Dermatologiques
[Show abstract][Hide abstract] ABSTRACT: Langerhans' cells are epidermal dendritic cells, derived from blood precursors. Their main function is antigen presentation to T-cells. They are able to express neuronal proteins, such as neuron-specific enolase or substance P-receptor. They are closely associated with nerve fibres. PGP9.5 is the most specific neuronal protein in the epidermis. Epidermal Langerhans' cells can express PGP9.5 if denervated. Using flow cytometry, we found that cultured CD34+ precursors did not express PGP9.5, whereas suspensions of fresh or cultured Langerhans' cells could express this neuronal protein. Precursors of Langerhans' cells are not able to express PGP9.5, suggesting that they are not mature enough or that the capacity to express PGP9.5 may be acquired only in the epidermis. The function of PGP9.5 on Langerhans' cells and mature dendritic cells remains unknown. PGP9.5 might be related to dendritic cell maturation or to the lack of contacts with nerve endings.
Full-text · Article · May 2000 · Acta Dermato Venereologica