Opposing effects of high- and low-molecular weight hyaluronan on CXCL12-induced CXCR4 signaling depend on CD44

The tumor microenvironment makes a decisive contribution to the development and dissemination of cancer, for example, through extracellular matrix components such as hyaluronan (HA), and through chemokines that regulate tumor cell behavior and angiogenesis. Here we report a molecular link between HA, its receptor CD44 and the chemokine CXCL12 in the regulation of cell motility and angiogenesis. High-molecular-weight HA (hHA) was found to augment CXCL12-induced CXCR4 signaling in both HepG2iso cells and primary human umbilical vein endothelial cells, as evidenced by enhanced ERK phosphorylation and increased cell motility. The augmentation of CXCR4 signaling translated into increased vessel sprouting and angiogenesis in a variety of assays. Small HA oligosaccharides (sHA) efficiently inhibited these effects. Both siRNA-mediated reduction of CD44 expression and antibodies that block the interaction of CD44 with HA provided evidence that CXCL12-induced CXCR4 signaling depends on the binding of hHA to CD44. Consistently, CD44 and CXCR4 were found to physically interact in the presence of CXCL12, an interaction that could be inhibited by sHA. These findings provide novel insights into how microenvironmental components interact with cell surface receptors in multi-component complexes to regulate key aspects of tumor growth and progression

In Vivo Dioxin Favors Interleukin-22 Production by Human CD4+ T Cells in an Aryl Hydrocarbon Receptor (AhR)-Dependent Manner

The transcription factor aryl hydrocarbon receptor (AhR) mediates the effects of a group of chemicals known as dioxins, ubiquitously present in our environment. However, it is poorly known how the in vivo exposure to these chemicals affects in humans the adaptive immune response. We therefore assessed the functional phenotype of T cells from an individual who developed a severe cutaneous and systemic syndrome after having been exposed to an extremely high dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).T cells of the TCDD-exposed individual were studied for their capacity to produce cytokines in response to polyclonal and superantigenic stimulation, and for the expression of chemokine receptors involved in skin homing. The supernatants from T cells of the exposed individual contained a substantially increased amount of interleukin (IL)-22 but not of IL-17A, interferon (IFN)-γ or IL-10 when compared to nine healthy controls. In vitro experiments confirmed a direct, AhR-dependent, enhancing effect of TCDD on IL-22 production by CD4+ T cells. The increased production of IL-22 was not dependent on AhR occupancy by residual TCDD molecules, as demonstrated in competition experiments with the specific AhR antagonist CH-223191. In contrast, it was due to an increased frequency of IL-22 single producing cells accompanied by an increased percentage of cells expressing the skin-homing chemokine receptors CCR6 and CCR4, identified through a multiparameter flow cytometry approach. Of interest, the frequency of CD4+CD25(hi)FoxP3+ T regulatory cells was similar in the TCDD-exposed and healthy individuals.This case strongly supports the contention that human exposure to persistent AhR ligands in vivo induce a long-lasting effect on the human adaptive immune system and specifically polarizes CD4+ T cells to produce IL-22 and not other T cell cytokines with no effect on T regulatory cells

Characterization of the skin microbiota in bullous pemphigoid patients and controls reveals novel microbial indicators of disease

Introduction: Bullous pemphigoid (BP) is the most common autoimmune blistering disease. It predominately afflicts the elderly and is significantly associated with increased mortality. The observation of age-dependent changes in the skin microbiota as well as its involvement in other inflammatory skin disorders suggests that skin microbiota may play a role in the emergence of BP blistering. We hypothesize that changes in microbial diversity associated with BP might occur before the emergence of disease lesions, and thus could represent an early indicator of blistering risk. Objectives: The present study aims to investigate potential relationships between skin microbiota and BP and elaborate on important changes in microbial diversity associated with blistering in BP. Methods: The study consisted of an extensive sampling effort of the skin microbiota in patients with BP and age- and sex-matched controls to analyze whether intra-individual, body site, and/or geographical variation correlate with changes in skin microbial composition in BP and/or blistering status. Results: We find significant differences in the skin microbiota of patients with BP compared to that of controls, and moreover that disease status rather than skin biogeography (body site) governs skin microbiota composition in patients with BP. Our data reveal a discernible transition between normal skin and the skin surrounding BP lesions, which is characterized by a loss of protective microbiota and an increase in sequences matching Staphylococcus aureus, a known inflammation-promoting species. Notably, Staphylococcus aureus is ubiquitously associated with BP disease status, regardless of the presence of blisters. Conclusion: The present study suggests Staphylococcus aureus may be a key taxon associated with BP disease status. Importantly, we however find contrasting patterns in the relative abundances of Staphylococcus hominis and Staphylococcus aureus reliably discriminate between patients with BP and matched controls. This may serve as valuable information for assessing blistering risk and treatment outcomes in a clinical setting

Expression of the chemokine receptor CCR5 in psoriasis and results of a randomized placebo controlled trial with a CCR5 inhibitor

Several reports have indicated that the chemokine receptor CCR5 and its ligands, especially CCL5 (formerly known as RANTES), may play a role in the pathogenesis of psoriasis. The purpose of this investigation was to examine the expression of CCR5 and its ligands in chronic plaque psoriasis and to evaluate the clinical and immunohistochemical effect of a CCR5 receptor inhibitor. Immunohistochemical analysis showed low but significant increased total numbers of CCR5 positive cells in epidermis and dermis of lesional skin in comparison to non-lesional skin. However, relative expression of CCR5 proportional to the cells observed revealed that the difference between lesional and non-lesional skin was only statistically significant in the epidermis for CD3 positive cells and in the dermis for CD68 positive cells. Quantification of mRNA by reverse transcriptase-polymerase chain reaction only showed an increased expression of CCL5 (RANTES) in lesional skin. A randomized placebo-controlled clinical trial in 32 psoriasis patients revealed no significant clinical effect and no changes at the immunohistochemical level comparing patients treated with placebo or a CCR5 inhibitor SCH351125. We conclude that although CCR5 expression is increased in psoriatic lesions, this receptor does not play a crucial role in the pathogenesis of psoriasis

Prostaglandin E2 regulates Th17 cell differentiation and function through cyclic AMP and EP2/EP4 receptor signaling

Prostaglandins, particularly prostaglandin E2 (PGE2), play an important role during inflammation. This is exemplified by the clinical use of cyclooxygenase 2 inhibitors, which interfere with PGE2 synthesis, as effective antiinflammatory drugs. Here, we show that PGE2 directly promotes differentiation and proinflammatory functions of human and murine IL-17–producing T helper (Th17) cells. In human purified naive T cells, PGE2 acts via prostaglandin receptor EP2- and EP4-mediated signaling and cyclic AMP pathways to up-regulate IL-23 and IL-1 receptor expression. Furthermore, PGE2 synergizes with IL-1β and IL-23 to drive retinoic acid receptor–related orphan receptor (ROR)-γt, IL-17, IL-17F, CCL20, and CCR6 expression, which is consistent with the reported Th17 phenotype. While enhancing Th17 cytokine expression mainly through EP2, PGE2 differentially regulates interferon (IFN)-γ production and inhibits production of the antiinflammatory cytokine IL-10 in Th17 cells predominantly through EP4. Furthermore, PGE2 is required for IL-17 production in the presence of antigen-presenting cells. Hence, the combination of inflammatory cytokines and noncytokine immunomodulators, such as PGE2, during differentiation and activation determines the ultimate phenotype of Th17 cells. These findings, together with the altered IL-12/IL-23 balance induced by PGE2 in dendritic cells, further highlight the crucial role of the inflammatory microenvironment in Th17 cell development and regulation

Tracing Functional Antigen-Specific CCR6+ Th17 Cells after Vaccination

BACKGROUND: The function of T helper cell subsets in vivo depends on their location, and one hallmark of T cell differentiation is the sequential regulation of migration-inducing chemokine receptor expression. CC-chemokine receptor 6 (CCR6) is a trait of tissue-homing effector T cells and has recently been described as a receptor on T helper type 17 (Th17) cells. Th17 cells are associated with autoimmunity and the defence against certain infections. Although, the polarization of Th cells into Th17 cells has been studied extensively in vitro, the development of those cells during the physiological immune response is still elusive. METHODOLOGY/PRINCIPAL FINDINGS: We analysed the development and functionality of Th17 cells in immune-competent mice during an ongoing immune response. In naïve and vaccinated animals CCR6(+) Th cells produce IL-17. The robust homeostatic proliferation and the presence of activation markers on CCR6(+) Th cells indicate their activated status. Vaccination induces antigen-specific CCR6(+) Th17 cells that respond to in vitro re-stimulation with cytokine production and proliferation. Furthermore, depletion of CCR6(+) Th cells from donor leukocytes prevents recipients from severe disease in experimental autoimmune encephalomyelitis, a model for multiple sclerosis in mice. CONCLUSIONS/SIGNIFICANCE: In conclusion, we defined CCR6 as a specific marker for functional antigen-specific Th17 cells during the immune response. Since IL-17 production reaches the highest levels during the immediate early phase of the immune response and the activation of Th17 cells precedes the Th1 cell differentiation we tent to speculate that this particular Th cell subset may represent a first line effector Th cell subpopulation. Interference with the activation of this Th cell subtype provides an interesting strategy to prevent autoimmunity as well as to establish protective immunity against infections

Hypoxia increases the metastatic ability of breast cancer cells via upregulation of CXCR4

<p>Abstract</p> <p>Background</p> <p>Chemokine SDF1α and its unique receptor CXCR4 have been implicated in organ-specific metastases of many cancers including breast cancer. Hypoxia is a common feature of solid tumors and is associated with their malignant phenotype. We hypothesized that hypoxia would upregulate CXCR4 expression and lead to increased chemotactic responsiveness to its specific ligand SDF1α.</p> <p>Methods</p> <p>Three breast cancer cell lines MDA-MB-231, MCF7 and 4T1 were subjected to 48 hrs of hypoxia or normoxia. Cell surface receptor expression was evaluated using flow cytometry. An extracellular matrix invasion assay and microporous migration assay was used to assess chemotactic response and metastatic ability.</p> <p>Results</p> <p>CXCR4 surface expression was significantly increased in the two human breast cancer cell lines, MDA-MB-231 and MCF7, following exposure to hypoxia. This upregulation of CXCR4 cell surface expression corresponded to a significant increase in migration and invasion in response to SDF1-α <it>in vitro</it>. The increase in metastatic potential of both the normoxic and the hypoxic treated breast cancer cell lines was attenuated by neutralization of CXCR4 with a CXCR4 neutralizing mAb, MAB172 or a CXCR4 antagonist, AMD3100, showing the relationship between CXCR4 overexpression and increased chemotactic responsiveness.</p> <p>Conclusions</p> <p>CXCR4 expression can be modulated by the tissue microenvironment such as hypoxia. Upregulation of CXCR4 is associated with increased migratory and invasive potential and this effect can be abrogated by CXCR4 inhibition. Chemokine receptor CXCR4 is a potential therapeutic target in the adjuvant treatment of breast cancer.</p

The role of dendritic cells in the immunopathogenesis of psoriasis

Psoriasis vulgaris is a chronic inflammatory skin disease that is marked by a complex interplay of dendritic cells (DCs), T-cells, cytokines, and downstream transcription factors as part of a self-sustaining type 1 cytokine network. As integral players of the immune system, DCs represent antigen-presenting cells that are crucial for efficient activation of T-cells and B-cells. DCs have also been linked to distinct chronic inflammatory conditions, including psoriasis. In the setting of psoriasis therapy, DC/T cell interactions serve as a potential target for biologic response modifiers. Here we describe the major DC subsets as well as the immunologic involvement of DCs within the context of psoriatic lesions

NK Cells Promote Th-17 Mediated Corneal Barrier Disruption in Dry Eye

The conjunctiva contains a specialized population of lymphocytes that reside in the epithelium, named intraepithelial lymphocytes (IEL).Here we characterized the IEL population prior to and after experimental desiccating stress (DS) for 5 or 10 days (DS5, DS10) and evaluated the effect of NK depletion on DS. The frequency of IELs in normal murine conjunctiva was CD3(+)CD103(+) (~22%), CD3(+)γδ(+) (~9.6%), CD3(+)NK(+) (2%), CD3(-)NK(+) (~4.4%), CD3(+)CD8α (~0.9%), and CD4 (~0.6%). Systemic depletion of NK cells prior and during DS led to a decrease in the frequency of total and activated DCs, a decrease in T helper-17(+) cells in the cervical lymph nodes and generation of less pathogenic CD4(+)T cells. B6.nude recipient mice of adoptively transferred CD4(+)T cells isolated from NK-depleted DS5 donor mice showed significantly less corneal barrier disruption, lower levels of IL-17A, CCL20 and MMP-3 in the cornea epithelia compared to recipients of control CD4(+)T cells.Taken together, these results show that the NK IELs are involved in the acute immune response to desiccation-induced dry eye by activating DC, which in turn coordinate generation of the pathogenic Th-17 response